ATRIAL NATRIURETIC FACTOR MUTANTS AND ISCHEMIC STROKE

Abstract: The present invention is based upon the observation that a mutant atrial natriuretic factor (ANF) gene increases stroke latency in spontaneously hypertensive rats-stroke prone (SHRSP). Accordingly, the present invention provides methods using mutant ANF proteins, fragments, analogs, derivatives and homologs of mutant ANF proteins, the nucleic acids encoding these mutant ANF proteins, as well as modulators of ANF for treating or preventing ischemic diseases, in particular ischemic stroke. The invention also relates to methods of diagnosis, prognosis and screening for a disposition for diseases and disorders associated with increased levels of ANF. Pharmaceutical compositions, methods of screening for ANF mutants and ANF modulators with utility for treatment and prevention of ischemic stroke are also provided.

Description: ATRIAL NATRIURETIC FACTOR MUTANTS AND ISCHEMIC STROKE 1. FIELD OF THE INVENTION This invention relates to mutants of atrial natriuretic factor, particularly mutants of atrial natriuretic factor that are protective for stroke. The invention further relates to methods of treating or preventing stroke by administration of mutants of atrial natriuretic factor. Additionally, the invention relates to methods of diagnosis, prognosis and screening for alleles of the atrial natriuretic factor gene that are protective for stroke. 2. BACKGROUND Ischemic stroke is a common, complex disorder caused by a combination of genetic and environmental factors that is associated with long term disability and death. Apart from the treatment of hypertension, a risk factor for stroke (Kannel et al., JAMA 214.301-310 (1970); Veterans Administration Cooperative Study Group on Antihypertensive Agents, Effects of treatment of morbidity in hypertension, JAMA 213:1143-1152 (1970)), few preventative therapeutics are available, and no genetic test for stroke predisposition exists. A significant genetic component to human stroke predisposition has been demonstrated by both rare monogenic inheritance (Palsdottir et al. Lancet 2..603-604 (1988); Boers et al., N. Eng. J. Meά . 313:709-715 (1985); Levy et al., Science 248:1124-1126 (1990)) and by increased concordance in onozygotic compared with dizygotic twins (De Faire et al., Prev. Med . 4 . :509-517 (1975); Brass et al. Stroke 23:221-223 (1992)). The spontaneously hypertensive stroke-prone rat (SHRSP) strain is an animal model of ischemic stroke. SHRSP rats suffer cerebrovascular events with 99% penetrance when administered a diet high in sodium to induce hypertension. These SHRSP rats are closely related to the SHR (spontaneously hypertensive rat) strain which develops hypertension, but not ischemic stroke, when administered a high sodium diet. Genetic analysis of the progeny of SHR- SHRSP rat intercrosses revealed that three Quantitative Trait Loci (QTLs) contribute to stroke latency (Rubattu et al., Nat . Gen . 13.:429-434 (1996)). While a locus on chromosome 1 significantly correlated with the occurrence of stroke, two loci, one on chromosome 4 and another on chromosome 5, were actually associated with increased stroke latency. The chromosome 5 locus mapped near the gene coding for ANF (atrial natriuretic factor) and BNF (brain natriuretic factor) . None of the three loci were associated with hypertension. A second study by Jeffs et al. (Nat . Gen . 16:364-367 (1997)) analyzed F2 progeny of intercrosses between the SHRSP animals and a normotensive, non-stroke rat strain Wistar- Kyoto (WKY) . A chromosome 5 locus, which also co-localized with ANF and BNF, was implicated in increased infarct susceptibility and severity in the SHRSP rats. ANF is a small peptide hormone known to have vasoactive and diuretic activities and functions both to relax smooth muscle and to reduce sodium reabsorption and intravascular volume (Needle an et al., Ann. Rev. Pharmacol . Toxicol . 2 :23-54 (1989)). ANF is derived from the prohormone atrial natriuretic peptide (ANP) which appears to be expressed in response to increased blood volume or sodium levels. The proANP is initially expressed as a single polypeptide chain and is proteolytically processed within the cell into four peptides, all of which have been implicated in the diuretic process of vasodilation: Long Acting Natriuretic Peptide, Vessel Dialator, Kaliuretic Peptide and Atrial Natriuretic Factor (Vesely et al., Metabolism: Clinical & Experimental 45: 315-319 (1996)). ANF is derived from amino acids 99-126 of ProANP. The physiological activity of ANF appears to be mediated through binding to the guanylate cyclase-A receptor by increasing secretion of cGMP into plasma and urine (Vesely et al., Amer. J. Med . Sci . 310:143-149 (1995); Miao et al., Hypertension 25_: 694-69 (1995)). Garcia et al. (Hypertension jL3_:567-574 (1989)) previously found that SHR had higher plasma ANF levels, and lower glomerular ANF receptor density, than normotensive controls. Additionally, Estrada et al. (Am . J. Hypertens . 2:1085-1089 (1994)) noted that elevated ANF levels have been detected in ischemic stroke patients. However, there has been no suggestion in the art that mutant ANF proteins or modulators (e.g., antagonists, agonists or inhibitors) of ANF would be useful as therapeutics or prophylactics for ischemic stroke. The present inventors have discovered that the ANF gene in the SHRSP strain has the glycine substituted with a serine residue at position 1 of rat ANF as depicted in Figure 2 (SEQ ID NO:l) (amino acid 99 of the proANP amino acid sequence as depicted in Figure 3 (SEQ ID NO: 2)). Furthermore, the present inventors have realized that this mutant ANF locus coincides with the chromosomal locus associated with increased stroke latency in the SHRSP animals. Accordingly, the ANF mutants and mutant ANF alleles described herein are useful in the treatment and prevention of ischemic stroke, and screening for a genetic predisposition for protection against ischemic stroke. Citation or discussion of a reference herein shall not be construed as an admission that such is prior art to the present invention. 3. SUMMARY OF THE INVENTION The present invention relates to mutants of ANF, preferably mutants of ANF and ANF derivatives, homologs, and fragments, preferably ANF mutants having one or more substitutions of amino acid residues and that binds to an anti-ANF antibody, more preferably an ANF mutant with a mutation at amino acid position 1 (of the rat or human ANF sequences as depicted in Figures 2 and 5, respectively (SEQ ID NOS:l and 4, respectively)), most preferably where the mutation at position 1 of ANF is a substitution of the glycine residue with a serine. The present invention further provides methods of treating or preventing stroke or ischemic disease, preferably ischemic stroke. In one embodiment, stroke or ischemic disease is treated or prevented by administration of a mutant ANF or a derivative, fragment or homolog thereof, preferably ANF mutants having one or more substitutions of amino acid residues and that bind to an anti-ANF antibody, more preferably an ANF mutant with a mutation at amino acid position 1 (of the rat ANF sequence as depicted in Figure 2; SEQ ID NO:l), most preferably where the mutation at position 1 of ANF is a substitution of the glycine residue with a serine. Pharmaceutical compositions are also provided. Also provided are methods of diagnosis, prognosis, and screening by detecting mutant ANF proteins and/or nucleic acids. In a preferred embodiment, an allele protective against stroke is screened for by detecting the presence of a mutation in the ANF gene or protein. Specific oligonucleotides that can be used to detect these mutant alleles are provided. Diagnostic, prognostic and screening kits are also provided. In another aspect of the invention, assays for screening for ANF mutants that are protective for stroke are provided. Additionally, the invention also includes methods of screening for modulators of ANF activity that affect stroke latency or stroke severity. 3.1. DEFINITIONS ANF Atrial Natriuretic Factor QEA™ Quantitative Expression Analysis SHR Spontaneously Hypertensive Rat SHRSP Spontaneously Hypertensive Rat Stroke-Prone WKY Wistar-Kyoto (Rat) 4. DESCRIPTION OF THE FIGURES Figures 1A-F. Panels A and B depict the profiles of the QEA™ labeled products in whole hearts from SHR (A) and SHR-SP (B) rats, with each trace representing results from an individual heart. The arrow below the X-axis indicates the position for ANF. Panels B and C show a comparison of the profiles for the QEA™ reactions for the SHR (C) and SHR-SP (D) hearts performed in the presence (lower trace) or absence (upper trace) of the "poisoning" oligonucleotide specific for the ANF gene. These profiles in panels A-D are depicted as the relative scaled intensity of the fluorescent label (on the Y-axis) versus the number of nucleotide bases (on the X- axis) . Panels E and F present the output from the automatic DNA sequencing of the ANF nucleotide sequence complementary to the sequence coding for the mutation at amino acid 1 of ANF. Panel E shows that portion of the ANF nucleotide sequence from SHR rats; Panel F shows that portion of the ANF nucleotide sequence from SHRSP rats. The position of the nucleotide substitution is indicated by an arrow. Figure 2. The amino acid sequence of wild type rat ANF (SEQ ID NO:l) (Genbank Accession No. K02062 and K02063 (1986)) . Figure 3. The amino acid sequence of wild type rat proANP (SEQ ID NO: 2) (Genbank Accession No. K02062 and K02063 (1986)) . Figure 4. The nucleotide sequence of wild type rat proANP (SEQ ID NO: 3) with the amino acid sequence indicated for the coding sequences (Genbank Accession No. K02062 and K02063 (1986)) . Figure 5. The amino acid sequence of human ANF (SEQ ID NO:4) (Genbank Accession No. M30262 (1990)). Figure 6. The amino acid sequence of human proANP (SEQ ID N0:5) (Genbank Accession No. M30262 (1990)). Figure 7. The nucleotide sequence of human proANP (SEQ ID NO: 6) with the amino acid sequence indicated for the coding sequences (Genbank Accession No. M30262 (1990)). The ANF sequence is amino acid residue numbers 100-127 (with amino acid number 100 corresponding to amino acid position 1 of rat ANF) . 5. DETAILED DESCRIPTION OF THE INVENTION The present inventors have discovered that the ANF gene in hypertensive stroke-prone rats (SHRSP) , an experimental animal model for stroke, has an amino acid substitution as compared to the ANF gene in spontaneously hypertensive rats (SHR) and wild type rats. The inventors have correlated the ANF gene with the major QTL (Quantitative Trait Locus) identified on chromosome 5 in SHRSP as a "protective locus" for stroke, i.e., presence of the QTL increases stroke latency. Sequence analysis of the ANF mRNA in SHRSP and comparison with ANF sequences obtained from sequence databases and from SHR revealed that the SHRSP ANF mutant gene encodes an ANF protein that has an amino acid substitution of serine for the glycine at position 1 of the rat ANF amino acid sequence as depicted in Figure 2 (SEQ ID NO:l). The glycine at amino acid 1 of ANF (amino acid 99 of proANP) is conserved among rat, pig, horse and human sequences. Accordingly, the invention relates to mutants of the ANF protein, as well as derivatives, fragments and homologs thereof, and ANF nucleic acids encoding them, that increase latency to stroke, e . g. , in stroke prone rats fed a high salt diet. Preferably, the ANF mutants bind to anti-(wild type) ANF antibodies. In particular, the invention relates to mutant ANFs having one or more substitutions of amino acid residues, preferably a mutant ANF that has an amino acid substitution at or corresponding to amino acid position 1 of rat or human ANF as depicted in Figures 2 and 5 (SEQ ID NOS:l and 4) (or amino acid position 99 of rat proANP as depicted in Figure 3 (SEQ ID NO: 2) or amino acid position 100 or human proANP as depicted in Figure 6 (SEQ ID NO: 5)), in particular a substitution of serine for the glycine at or corresponding to position 1 of rat or human ANF. One embodiment of the invention provides methods of treatment and prevention of stroke by administration of a mutant ANF protein, or a derivative, fragment or homolog thereof, as provided by the invention. In a preferred embodiment, the mutant ANF, or derivative, fragment or homolog thereof, has an amino acid substitution at or corresponding to amino acid position 1 of rat or human ANF as depicted in Figures 2 and 5, respectively (SEQ ID N0S:1 and 4, respectively), in particular, a substitution of serine for the glycine at or corresponding to position 1 of rat or human ANF. Pharmaceutical compositions are also provided. Another aspect of the invention relates to methods of diagnosis, prognosis and screening for stroke by detecting mutant ANF protein or mRNA. In one embodiment, subjects are screened for a mutant ANF allele protective against stroke. The present invention also relates to methods of assaying ANF mutants for the ability to affect the predisposition to or onset of stroke and to methods of screening for ANF modulators (i.e. agonists, antagonists and inhibitors of ANF) . 5.1. ANF MUTANTS ANF mutant proteins, and mutants of derivatives, fragments, homologs and analogs of ANF proteins and the nucleic acids encoding the ANF mutants, protein derivatives and protein analogs are provided by the invention. The ANF mutants of the invention can be ANF proteins having substitutions, deletions or insertions of one, two, three, or more amino acid residues in the wild type ANF protein. Preferably, the ANF mutants bind to an anti-ANF antibody. In one embodiment, the mutant ANF has one or more substitutions of amino acid residues relative to the wild type ANF protein, preferably, one or more amino acid substitutions in the amino acid residues (or in the amino acid residues corresponding to the amino acid residues) selected from among amino terminal residues 1-25, 1-20, 1-15, 1-10, 1-5 or 1-2 of ANF as depicted in Figures 2 or 5 (SEQ ID NOS: 1 and 4, respectively) . In a preferred embodiment, the mutant ANF has an amino acid substitution at amino acid position 1 of the rat ANF sequence provided in Figure 2 (SEQ ID NO:l) or the corresponding position (i.e., as identified by aligning the amino acids having sequence identity between or among the rat ANF amino acid sequence and the amino acid sequence (s) of ANF proteins of other species) of the ANF protein of another species (e.g., amino acid position 1 of human ANF as depicted in Figure 5 (SEQ ID NO: 4)). In a more preferred embodiment, the amino acid at amino acid 1 of rat or human ANF as depicted in Figures 2 and 5, respectively (SEQ ID NOS:l and 4, respectively), or the at the corresponding amino acid position in a non-rat ANF protein, is substituted with a residue that provides a substrate for kinase activity, e .g. a substitution with a residue from the group consisting of serine, threonine and tyrosine, preferably substitution with a serine residue. In a preferred embodiment, the ANF mutant is a human ANF mutant having amino acid substitutions as its only mutations and that binds an anti-ANF antibody. In another embodiment, the ANF mutant increases latency to stroke in stroke prone rats (e . g. rats having the stroke predisposing locus of chromosome 1) fed a high salt diet (for example, but not limited to, a diet of 17.5% protein, 3.7 mg/g Na + , 6.3 mg/kg K + , and 0.03 mg/g methionine and 1% NaCl drinking water) . In a specific embodiment of the invention, proteins consisting of or comprising a fragment of an ANF protein or mutant protein consisting of at least 10 (continuous) amino acids of the ANF protein are provided. In other embodiments, the fragment consists of at least 15 or 20 or 25 amino acids of the ANF protein. In a preferred embodiment, the ANF fragment contains the portion of a mutant ANF having the mutation at or corresponding to amino acid position 1 of the amino acid sequence of rat or human ANF as depicted in Figures 2 or 5, respectively (SEQ ID NOS:l or 4, respectively) , more preferably with a serine residue substituted for the glycine at position 1. Derivatives or analogs of ANF include but are not limited to those molecules comprising regions that are substantially homologous to ANF or mutant ANF or fragments thereof (e .g. , in various embodiments, at least 60% or 70% or 80% or 90% or 95% identity over an amino acid sequence of identical size or when compared to an aligned sequence in which the alignment is done by a computer homology program known in the art) or whose encoding nucleic acid is capable of hybridizing to a coding ANF sequence, under stringent, moderately stringent, or nonstringent conditions. The ANF mutants, as well as fragments, derivatives, homologs and analogs ANF mutants, of the invention can be produced by various methods known in the art. The manipulations which result in their production can occur at the gene or protein level. For example, the cloned ANF gene sequence (e .g . as described in Section 5.2 infra) can be modified by any of numerous strategies known in the art (Sambrook et al., 1990, Molecular Cloning, A Laboratory Manual, 2d ed. , Cold Spring Harbor Laboratory, Cold Spring Harbor, New York) . The sequence can be cleaved at appropriate sites with restriction endonuclease (s) , followed by further enzymatic modification if desired, isolated, and ligated in vitro. In the production of the gene encoding a mutant, derivative or analog of ANF, care should be taken to ensure that the modified gene remains within the same translational reading frame as ANF, uninterrupted by tranεlational stop signals, in the gene region where the desired ANF activity is encoded. The ANF-encoding nucleic acid sequence can be mutated in vitro or in vivo, to make changes in the coding regions (e.g. amino acid substitutions, additions or deletions) as well aε to create and/or destroy translation, initiation, and/or termination sequences, or to form new restriction endonuclease sites or destroy preexisting ones, to facilitate further in vitro modification. Any technique for mutagenesis known in the art can be used, including but not limited to, chemical mutagenesis, in vitro site-directed mutagenesis (Hutchinson, C, et al., 1978, J. Biol. Chem 253:6551), use of TAB ® linkers (Pharmacia) , etc. Manipulations of the ANF sequence may also be made at the protein level. Included within the scope of the invention are ANF protein fragments or other derivatives or analogs which are differentially modified during or after translation, e . g. , by glycosylation, acetylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to an antibody molecule or other cellular ligand, etc. Any of numerous chemical modifications may be carried out by known techniques, including but not limited to specific chemical cleavage by cyanogen bromide, trypsin, chymotrypsin, papain, V8 protease, NaBH 4 ; acetylation, formylation, oxidation, reduction; metabolic synthesis in the presence of tunicamycin; etc. Particularly included within the invention are those modifications which reduce the level or activity of ANF. In addition, ANF mutants, analogs and derivatives can be chemically synthesized. For example, mutant ANF proteins or a portion thereof, which mediate the desired activity in vivo or in vitro, can be synthesized by use of a peptide synthesizer. Furthermore, if desired, nonclassical amino acids or chemical amino acid analogs can be introduced as a substitution or addition into the ANF sequence. Nonclassical amino acids include but are not limited to the D- isomers of the common amino acids, α-amino isobutyric acid, 4-aminobutyric acid, Abu, 2-amino butyric acid, γ-Abu, e-Ahx, 6-amino hexanoic acid, Aib, 2-amino isobutyric acid, 3-amino propionic acid, ornithine, norleucine, norvaline, hydroxyproline, sarcosine, citrulline, cysteic acid, t- butylglycine, t-butylalanine, phenylglycine, cyclohexylalanine, S-alanine, fluoro-amino acids, designer amino acids such as β-methyl amino acids, Cα-methyl amino acids, Nα-methyl amino acids, and amino acid analogs in general. Furthermore, the amino acid can be D (dextrorotary) or L (levorotary) . In another embodiment, the ANF derivative is a chimeric, or fusion, protein comprising an ANF protein or fragment thereof (preferably consisting of at least 10 amino acids of the ANF protein or a mutant ANF protein) joined at its a ino- or carboxy-terminus via a peptide bond to an amino acid sequence of a different protein. In one embodiment, such a chimeric protein is produced by recombinant expression of a nucleic acid encoding the protein (comprising an ANF-coding sequence joined in-frame to a coding sequence for a different protein) . Such a chimeric product can be made by ligating the appropriate nucleic acid sequences encoding the desired amino acid sequences to each other by methods known in the art, in the proper coding frame, and expressing the chimeric product by methods commonly known in the art. Alternatively, such a chimeric product may be made by protein synthetic techniques, e . g. , by use of a peptide synthesizer. Chimeric genes comprising portions of ANF or mutant ANF fused to any heterologous protein-encoding sequences may be constructed. A specific embodiment relates to a chimeric protein comprising a fragment of ANF or mutant ANF of at least six amino acids. Additionally, due to the degeneracy of nucleotide coding sequences, other DNA sequences which encode substantially the same amino acid sequence as a mutant ANF of the invention may be used in the practice of the present invention. The mutant ANF genes of the invention can be obtained by alteration of nucleotide sequences comprising all or portions of ANF gene by the substitution of different codons that encode the desired amino acid. Additionally, one or more codons encoding a functionally equivalent amino acid residue within the sequence may also be substituted, thus producing a silent change. For example, one or more amino acid residues within the sequence can be substituted by another amino acid of a similar polarity which acts as a functional equivalent, resulting in a silent alteration. Substitutes for an amino acid within the sequence may be selected from other members of the class to which the amino acid belongs. For example, the nonpolar (hydrophobic) amino acids include alanine, leucine, isoleucine, valine, proline, phenylalanine, tryptophan and methionine. The polar neutral amino acids include glycine, serine, threonine, cysteine, tyrosine, asparagine, and glutamine. The positively charged (basic) amino acids include arginine, lysine and histidine. The negatively charged (acidic) amino acids include aspartic acid and glutamic acid. The invention also provides mutant proANP molecules, containing the mutations as described above for mutant ANF molecules. 5.2. ANF GENES AND PROTEINS ANF proteins and nucleic acids can be obtained by any method known in the art. The ANF amino acid and nucleotide sequences for, inter alia , human, rat, hamster, dog, mouse, bovine, porcine, Drosophila mel anog aster , Xenopus, horse, and dogfish are available in the public databases (e . g. Genbank) . The amino acid sequence for rat ANF, the amino acid sequence for rat ANP, the nucleotide sequence for rat ANP, the amino acid sequence for human ANF, the amino acid sequence for human ANP and the nucleotide sequence for human ANF are provided in Figures 2-7, respectively (SEQ ID NOS: 1-6, respectively) . Any eukaryotic cell potentially can serve as the nucleic acid source for the isolation of ANF nucleic acids. The nucleic acid sequences encoding ANF can be isolated from vertebrate, mammalian, human, porcine, bovine, feline, avian, equine, canine, as well as additional primate sources, etc. The DNA may be obtained by standard procedures known in the art from cloned DNA (e.g., a DNA "library"), by chemical synthesis, by cDNA cloning, or by the cloning of genomic DNA, or fragments thereof, purified from the desired cell (see, for example, Sambrook et al., 1989, Molecular Cloning, A Laboratory Manual, 2d Ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York; Glover, D.M. (ed.), 1985, DNA Cloning: A Practical Approach, MRL Press, Ltd., Oxford, U.K. Vol. I, II.) Clones derived from genomic DNA may contain regulatory and intron DNA regions in addition to coding regions; clones derived from cDNA will contain only exon sequences. Whatever the source, the gene should be molecularly cloned into a suitable vector for propagation of the gene. In the molecular cloning of the gene from cDNA, cDNA is generated from totally cellular RNA or mRNA by methods that are well known in the art. The gene may also be obtained from genomic DNA, where DNA fragments are generated (e.g. using restriction enzymes or by mechanical shearing) , some of which will encode the desired gene. The linear DNA fragments can then be separated according to size by standard techniques, including but not limited to, agaroεe and polyacrylamide gel electrophoresis and column chromatography. Once the DNA fragments are generated, identification of the specific DNA fragment containing all or a portion of the ANF gene may be accomplished in a number of ways. A preferred method for isolating an ANF gene is by the polymerase chain reaction (PCR) , which can be used to amplify the desired ANF sequence in a genomic or cDNA library or from genomic DNA or cDNA that has not been incorporated into a library. Oligonucleotide primers which would hybridize to ANF sequences can be used as primers in PCR. For example, primers having the sequence 5'-GAATTCAGTTCTCTCCTTCCGCT-3' (SEQ ID NO: 7) and 5'-CATGCTGGCGTGGGACGGGGCAC-3 ' (SEQ ID NO: 8) can be used to amplify the rat ANF sequence, and primers having the sequence 5'-GGATCCATTTGTCTCGGGCTG-3 ' (SEQ ID NO: 9) and 5'-CTAGATCAATTAGGCCTCCC-3 ' (SEQ ID NO: 10) can be used to amplify the human ANF sequence. The synthetic oligonucleotides may be utilized as primers to amplify by PCR sequences from a source (RNA or DNA) , preferably a cDNA library, of potential interest. PCR can be carried out, e.g., by use of a Perkin-Elmer Cetuε thermal cycler and Taq polymerase (Gene Amp™) . One can choose to synthesize several different degenerate primers for use in the PCR reactions. It is also possible to vary the stringency of hybridization conditions used in priming the PCR reactions, to allow for greater or lesser degrees of nucleotide sequence similarity between the known ANF nucleotide sequence and the nucleic acid of an ANF homolog being isolated. For crosε species hybridization, low stringency conditions are preferred. For same species hybridization, moderately stringent conditions are preferred. After successful amplification of a segment of an ANF homolog, that segment may be molecularly cloned and sequenced, and utilized as a probe to isolate a complete cDNA or genomic clone. This, in turn, will permit the determination and isolation of the gene's complete nucleotide sequence. PCR amplification can also be uεed to detect and quantitate ANF mRNA levels for, e . g. the diagnostic, prognostic and screening methods described Section 5.4 supra . Additionally, a portion of the ANF (of any species) gene or its specific RNA, or a fragment thereof, can be purified (or an oligonucleotide synthesized) and labeled, the generated DNA fragments may be screened by nucleic acid hybridization to the labeled probe (Benton, W. and Davis, R. , 1977, Science 196:180; Grunstein, M. And Hognesε, D. , 1975, Proc. Natl. Acad. Sci. U.S.A. 72:3961). Those DNA fragments with substantial homology to the probe will hybridize. ANF nucleic acids can be also identified and isolated by expression cloning using, for example, anti-ANF antibodies for selection. Alternativeε to obtaining the ANF DNA by cloning or amplification include, but are not limited to, chemically synthesizing the gene sequence itself from the known ANF sequence or making cDNA to the mRNA which encodes the ANF protein. Other methods are possible and within the scope of the invention. Once a clone has been obtained, its. identity can be confirmed by nucleic acid sequencing (by any method well known in the art) and comparison to known ANF sequenceε. DNA sequence analysis can be performed by any techniques known in the art, including but not limited to the method of Maxam and Gilbert (1980, Meth. Enzy ol. 65:499-560), the Sanger dideoxy method (Sanger, F., et al., 1977, Proc. Natl. Acad. Sci. U.S.A. 74:5463), the uεe of T7 DNA polymerase (Tabor and Richardson, U.S. Patent No. 4,795,699), uεe of an automated DNA sequenator (e.g., Applied Biosystems, Foεter City, CA) or the method described in PCT Publication WO 97/ 15690. Nucleic acids which are hybridizable to an ANF nucleic acid (e.g., having sequence SEQ ID NO: 3 or 6), or to a nucleic acid encoding an ANF derivative can be isolated, by nucleic acid hybridization under conditions of low, high, or moderate stringency. By way of example and not limitation, procedures using such conditions of low stringency are as followε (see also Shilo and Weinberg, 1981, Proc. Natl. Acad. Sci. USA 78:6789-6792): Filters containing DNA are pretreated for 6 h at 40°C in a solution containing 35% forma ide, 5X SSC, 50 mM Tris-HCl (pH 7.5), 5 mM EDTA, 0.1% PVP, 0.1% Ficoll, 1% BSA, and 500 μg/ml denatured salmon sperm DNA. Hybridizations are carried out in the same solution with the following modifications: 0.02% PVP, 0.02% Ficoll, 0.2% BSA, 100 μg/ml salmon sperm DNA, 10% (wt/vol) dextran sulfate, and 5-20 X 10 s cpm 3 P-labeled probe is used. Filters are incubated in hybridization mixture for 18-20 h at 40°C, and then washed for 1.5 h at 55°C in a solution containing 2X SSC, 25 mM Tris-HCl (pH 7.4), 5 mM EDTA, and 0.1% SDS. The wash solution is replaced with fresh solution and incubated an additional 1.5 h at 60°C. Filters are blotted dry and exposed for autoradiography. If necesεary, filterε are waεhed for a third time at 65-68 °C and reexposed to film. Other conditions of low stringency which may be used are well known in the art (e.g., as employed for cross- species hybridizations) . By way of example and not limitation, procedures uεing such conditions of high stringency are as follows: Prehybridization of filters containing DNA is carried out for 8 h to overnight at 65°C in buffer composed of 6X SSC, 50 mM Tris-HCl (pH 7.5), 1 mM EDTA, 0.02% PVP, 0.02% Ficoll, 0.02% BSA, and 500 μg/ml denatured salmon sperm DNA. Filterε are hybridized for 48 h at 65°C in prehybridization mixture containing 100 μg/ml denatured εalmon sperm DNA and 5-20 X 10 6 cpm of 32 P-labeled probe. Washing of filters iε done at 37°C for 1 h in a εolution containing 2X SSC, 0.01% PVP, 0.01% Ficoll, and 0.01% BSA. Thiε iε followed by a waεh in 0.1X SSC at 50°C for 45 min before autoradiography. Other conditions of high stringency which may be used are well known in the art. For example, but not limited to, procedures using such conditions of moderate εtringency are aε followε: Filterε containing DNA are pretreated for 6 h at 55°C in a solution containing 6X SSC, 5X Denhart'ε solution, 0.5% SDS and 100 μg/ml denatured salmon sperm DNA. Hybridizations are carried out in the εame εolution and 5-20 X 10 6 cpm 32 P-labeled probe iε uεed. Filters are incubated in hybridization mixture for 18-20 h at 55°C, and then washed twice for 30 minutes at 60°C in a solution containing IX SSC and 0.1% SDS. Filterε are blotted dry and expoεed for autoradiography. Other conditionε of moderate stringency which may be used are well- known in the art. Washing of filters is done at 37°C for 1 h in a solution containing 2X SSC, 0.1% SDS. Nucleic acids encoding derivatives and analogs of ANF proteins (εee Section 5.1), ANF antiεenεe nucleic acids (see Section 5.3.4), and primers that can be used to detect mutant ANF alleleε and ANF gene expreεεion are additionally provided. Aε iε readily apparent, aε uεed herein, a "nucleic acid encoding a fragment or portion of an ANF protein" shall be construed as referring to a nucleic acid encoding only the recited fragment or portion of the ANF protein and not the other contiguous portions of the ANF protein as a continuouε sequence. ANF proteins and derivatives, analogs and fragments of ANF proteins can be obtained by any method known in the art, including but not limited to recombinant expression methods, purification from natural sources, and chemical synthesiε. For example, ANF can be obtained by recombinant protein expreεεion techniques. For recombinant expresεion, the ANF gene or portion thereof iε inεerted into an appropriate cloning vector for expreεεion in a particular host cell. A large number of vector-host syεtems known in the art may be used. Posεible vectorε include, but are not limited to, plaεmidε or modified viruses, but the vector syεtem muεt be compatible with the host cell used. Such vectors include, but are not limited to, bacteriophages such as lambda derivatives, or plasmidε εuch aε pBR322 or pUC plaεmid derivativeε or the Blueεcript vector (Stratagene) . The inεertion into a cloning vector can, for example, be accompliεhed by ligating the DNA fragment into a cloning vector which haε complementary coheεive termini. However, if the complementary reεtriction εites used to fragment the DNA are not present in the cloning vector, the ends of the DNA molecules may be enzymatically modified. Alternatively, any site deεired may be produced by ligating nucleotide εequences (linkers) onto the DNA termini; theεe ligated linkerε may compriεe εpecific chemically synthesized oligonucleotides encoding reεtriction endonucleaεe recognition εequenceε. In an alternative method, the cleaved vector and ANF gene may be modified by homopolymeric tailing. Recombinant molecules can be introduced into host cells via transformation, transfection, infection, electroporation, etc., εo that many copieε of the gene εequence are generated. In an alternative method, the deεired gene may be identified and iεolated after insertion into a suitable cloning vector in a "shot gun" approach. Enrichment for the desired gene, for example, by size fractionation, can be done before insertion into the cloning vector. In εpecific embodimentε, tranεformation of hoεt cellε with recombinant DNA moleculeε that incorporate the iεolated ANF gene, cDNA, or εynthesized DNA sequence enables generation of multiple copies of the gene. Thus, the gene may be obtained in large quantitieε by growing tranεformantε, iεolating the recombinant DNA moleculeε from the transformants and, when neceεsary, retrieving the inserted gene from the isolated recombinant DNA. The nucleotide sequence coding for an ANF protein or a functionally active analog or fragment or other derivative thereof, can be inserted into an appropriate expression vector, i.e., a vector which contains the necessary elements for the transcription and translation of the inεerted protein-coding εequence. The necessary transcriptional and translational signals can alεo be εupplied by the native ANF gene and/or itε flanking regionε. A variety of hoεt-vector εystems may be utilized to expreεε the protein-coding sequence. These include but are not limited to mammalian cell εyεtemε infected with viruε (e.g., vaccinia virus, adenovirus, etc.); insect cell syεtemε infected with viruε (e.g., baculoviruε) ; microorganiεmε εuch as yeast containing yeaεt vectorε, or bacteria tranεformed with bacteriophage, DNA, plaεmid DNA, or cosmid DNA. The expresεion elementε of vectorε vary in their εtrengthε and εpecificitieε. Depending on the hoεt-vector εystem utilized, any one of a number of suitable tranεcription and tranεlation elementε may be used. Any of the methods previouεly deεcribed for the inεertion of DNA fragmentε into a vector may be used to construct expression vectors containing a chimeric gene consisting of appropriate transcriptional/tranεlational control εignalε and the protein coding εequenceε. These methods may include in vitro recombinant DNA and synthetic techniques and in vivo recombinants (genetic recombination) . Expreεεion of nucleic acid εequence encoding an ANF protein or peptide fragment may be regulated by a second nucleic acid sequence so that the ANF protein or peptide is expressed in a host tranεformed with the recombinant DNA molecule. For example, expreεεion of an ANF protein may be controlled by any promoter/enhancer element known in the art. Promoterε which may be uεed to control ANF expreεεion include, but are not limited to, the SV40 early promoter region (Bernoiεt and Chambon, 1981, Nature 290:304-310), the promoter contained in the 3' long terminal repeat of Rous sarcoma virus (Yamamoto, et al., 1980, Cell 22:787-797), the herpes thymidine kinase promoter (Wagner et al., 1981, Proc. Natl. Acad. Sci. U.S.A. 78:1441-1445), the regulatory εequences of the metallothionein gene (Brinster et al., 1982, Nature 296:39- 42) ; prokaryotic expreεεion vectorε εuch as the S-lactamase promoter (Villa-Ka aroff, et al., 1978, Proc. Natl. Acad. Sci. U.S.A. 75:3727-3731), or the tac promoter (DeBoer, et al., 1983, Proc. Natl. Acad. Sci. U.S.A. 80:21-25); see also "Useful proteins from recombinant bacteria" in Scientific American, 1980, 242:74-94; promoter elements from yeast or 5 other fungi such as the Gal 4 promoter, the ADC (alcohol dehydrogenase) promoter, PGK (phoεphoglycerol kinaεe) promoter, alkaline phoεphataεe promoter, and the following animal tranεcriptional control regionε, which exhibit tiεsue specificity and have been utilized in transgenic animals: 10 elastase I gene control region which is active in pancreatic acinar cellε (Swift et al., 1984, Cell 38:639-646; Ornitz et al., 1986, Cold Spring Harbor Symp. Quant. Biol. 50:399-409; MacDonald, 1987, Hepatology 7:425-515); inεulin gene control region which iε active in pancreatic beta cellε (Hanahan, 15 1985, Nature 315:115-122), immunoglobulm gene control region which iε active in lymphoid cellε (Groεschedl et al., 1984, Cell 38:647-658; Adames et al., 1985, Nature 318:533-538; Alexander et al., 1987, Mol. Cell. Biol. 7:1436-1444), mouεe mammary tumor viruε control region which iε active in 20 teεticular, breaεt, lymphoid and maεt cellε (Leder et al., 1986, Cell 45:485-495), albumin gene control region which iε active in liver (Pinkert et al., 1987, Geneε and Devel. 1:268-276), alpha-fetoprotein gene control region which is active in liver (Krumlauf et al., 1985, Mol. Cell. Biol. 25 5:1639-1648; Hammer et al., 1987, Science 235:53-58; alpha 1- antitrypεin gene control region which iε active in the liver (Kelεey et al., 1987, Genes and Devel. 1:161-171), beta- globin gene control region which is active in myeloid cells (Mogram et al., 1985, Nature 315:338-340; Kollias et al., 30 1986, Cell 46:89-94), myelin basic protein gene control region which iε active in oligodendrocyte cellε in the brain (Readhead et al., 1987, Cell 48:703-712), myoεin light chain- 2 gene control region which iε active in skeletal muscle (Sani, 1985, Nature 314:283-286), and gonadotropic releasing 35 hormone gene control region which is active in the hypothalamus (Maεon et al., 1986, Science 234:1372-1378). For example, a vector can be used that comprises a promoter operably linked to an ANF-encoding nucleic acid, one or more origins of replication, and, optionally, one or more selectable markers (e.g., an antibiotic resistance gene). In a specific embodiment, an expression construct is made by subcloning an ANF coding εequence into the -5coRI restriction site of each of the three pGEX vectors (Glutathione S-Transferase expresεion vectorε; Smith and Johnεon, 1988, Gene 7:31-40). Thiε allowε for the expreεsion of the ANF protein product from the subclone in the correct reading frame. Expreεεion vectors containing ANF gene inserts can be identified by three general approaches: (a) nucleic acid hybridization, (b) presence or absence of "marker" gene functionε, and (c) expreεsion of inserted sequences. In the first approach, the presence of an ANF gene inserted in an expreεsion vector can be detected by nucleic acid hybridization uεing probeε comprising sequences that are homologous to an inserted ANF gene. In the second approach, the recombinant vector/host syεtem can be identified and selected based upon the presence or absence of certain "marker" gene functionε (e.g., thymidine kinaεe activity, reεiεtance to antibiotics, transformation phenotype, occlusion body formation in baculovirus, etc.) caused by the insertion of an ANF gene in the vector. For example, if the ANF gene is inserted within the marker gene sequence of the vector, recombinants containing the ANF insert can be identified by the absence of the marker gene function. In the third approach, recombinant expresεion vectorε can be identified by aεεaying the ANF product expreεεed by the recombinant. Such assays can be based, for example, on the physical or functional properties of the ANF protein in in vitro assay systems, e . g. , binding with anti-ANF antibody or the ANF receptor. Once a particular recombinant DNA molecule is identified and isolated, several methods known in the art may be used to propagate it. Once a suitable hoεt εyεtem and growth conditions are establiεhed, recombinant expreεεion vectorε can be propagated and prepared in quantity. As previously explained, the expression vectors which can be used include, but are not limited to, the following vectors or their derivativeε: human or animal viruses εuch as vaccinia virus or adenovirus; insect viruseε εuch aε baculoviruε; yeast vectors; bacteriophage vectors (e.g., lambda), and plasmid and coεmid DNA vectors, to name but a few. In addition, a host cell strain may be chosen which modulateε the expreεεion of the inserted sequences, or modifies and processes the gene product in the specific fashion desired. Expresεion from certain promoterε can be elevated in the preεence of certain inducers; thus, expresεion of the genetically engineered ANF protein may be controlled. Furthermore, different hoεt cellε have characteristic and specific mechanisms for the tranεlational and poεt-translational processing and modification (e.g., glycosylation, phoεphorylation of proteins. Appropriate cell lines or hoεt εyεtemε can be choεen to enεure the deεired modification and processing of the foreign protein expresεed. For example, expreεεion in a bacterial system can be used to produce an unglycosylated core protein product. Expression in yeast will produce a glycoεylated product. Expreεsion in mammalian cellε can be uεed to enεure "native" glycoεylation of a heterologouε protein. Furthermore, different vector/hoεt expression syεtemε may effect proceεsing reactions to different extents. In other specific embodiments, the ANF protein, fragment, analog, or derivative may be expressed as a fusion, or chimeric protein product (comprising the protein, fragment, analog, or derivative joined via a peptide bond to a heterologous protein sequence (of a different protein) ) . Such a chimeric product can be made by ligating the appropriate nucleic acid sequences encoding the desired amino acid sequences to each other by methods known in the art, in the proper coding frame, and expressing the chimeric product by methods commonly known in the art. Alternatively, such a chimeric product may be made by protein synthetic techniques, e.g., by use of a peptide synthesizer. Both cDNA and genomic sequences can be cloned and expresεed. The ANF protein may alεo be iεolated and purified by εtandard methodε including chromatography (e.g., ion exchange, affinity, and εizing column chromatography) , centrifugation, differential εolubility, or by any other εtandard technique for the purification of proteinε. The functional propertieε may be evaluated using any suitable asεay (see Section 5.5) . Alternatively, the protein can be syntheεized by standard chemical methods known in the art (e.g., see Hunkapiller, M. , et al., 1984, Nature 310:105- 111) . In another alternate embodiment, native ANF proteinε can be purified from natural εources, by standard methods such as those described above (e.g., immunoaffinity purification). 5.3. METHODS OF TREATMENT The present invention provides methods of treating and preventing ischemic diseases and disorderε and cerebrovascular diseases and disorderε (primarily εtroke, preferably iεchemic stroke) by administration of a therapeutic compound (termed herein "Therapeutic") of the invention. In one aspect of the invention, such "Therapeutics" include ANF mutant proteins and analogε, derivativeε and fragmentε thereof (e.g., as described hereinabove) and nucleic acids encoding the mutant ANF proteinε, analogs, derivatives, or fragmentε (e.g., aε described hereinabove) . In one embodiment, the Therapeutic is a mutant ANF having one or more εubεtitutions of amino acid residues relative to the wild type ANF protein, preferably, one or more amino acid subεtitutionε in the amino acid reεidueε selected from among amino-terminal reεidueε 1-25, 1-20, 1-15, 1-10, 1-5 or 1-2 of ANF as depicted in Figures 2 or 5 (SEQ ID NOS: 1 and 4, respectively). In a preferred embodiment, the Therapeutic is a mutant ANF having an amino acid substitution at amino acid position 1 of the rat ANF sequence provided in Figure 2 (SEQ ID NO:l) or the corresponding position (i.e., as identified by aligning the amino acids having sequence identity between or among the rat ANF amino acid sequence and the amino acid sequence (ε) of ANF proteinε of other εpecies) of the ANF protein of another specieε (preferably human ANF at amino acid poεition 1 aε depicted in Figure 5 (SEQ ID NO:4)), more preferably a mutant ANF where the amino acid at amino acid 1 of rat ANF aε depicted in Figure 2 (SEQ ID NO:l), or the at the correεponding amino acid poεition in a non-rat ANF protein (preferably amino acid poεition 1 of human ANF aε depicted in Figure 5 (SEQ ID NO: 4)), is substituted by a residue that provides a substrate for kinase activity, e.g. a substitution with a residue from the group consisting of serine, threonine and tyrosine, preferably εubεtitution with a εerine residue. In another embodiment, an ANF mutant increases latency to stroke in stroke prone rats (e.g., rats having the stroke predisposing locus of chromoεome 1) fed a high εalt diet (for example, but not limited to a diet of 17.5% protein, 3.7 mg/g Na + , 6.3 mg/kg K + , and 0.03 mg/g methionine and 1% NaCl drinking water) iε administered to treat or prevent stroke. The subject to which the Therapeutic is administered is preferably an animal, including but not limited to animalε εuch aε cowε, pigε, horses, chickens, cats, dogs, etc., and is preferably a mammal. In a preferred embodiment, the subject is a human. Generally, administration of products of a specieε origin or specieε reactivity (in the caεe of antibodies) that is the same species as that of the subject is preferred. Thuε, in a preferred embodiment, a human mutant ANF protein, derivative, or analog, or nucleic acid, iε therapeutically or prophylactically adminiεtered to a human patient. The ANF mutantε of the invention protective againεt stroke, particularly the ANF mutant having an amino acid substitution at position 1 of rat or human ANF as depicted in Figures 2 and 5, respectively (SEQ ID NOS:l and 4, respectively) , can be asεayed by any of the methodε deεcribed in Section 5.5 infra (for example, but not limited to, ANF receptor binding or signaling asεayε, e.g. aε indicated by changeε in cGMP levelε, or detection of altered cGMP levelε in plaεma or urine, reduction in blood pressure, diuretic effect, etc. , in vivo) to determine if the ANF mutant protective for stroke has higher or lower physiological activity than the wild type ANF. In the event it is determined that the mutant ANF proteins protective against stroke have a lower physiological activity than wild type ANF, then molecules that inhibit ANF activity (e.g. ANF antagonists and inhibitors) , such aε anti-ANF antibodies and ANF anti-sense nucleic acids, are also envisioned for use to treat or prevent ischemic disease, preferably iεchemic stroke. Accordingly, in a specific embodiment of the invention, ANF antagonistε and inhibitorε, including but not limited to anti-ANF antibodieε (e.g. aε deεcribed below) and ANF anti- senεe nucleic acidε (e.g. as described below) and ANF derivatives (e.g., that are competitive inhibitors of ANF) are administered to treat or prevent stroke or ischemic diseaεe, preferably ischemic stroke. Alternatively, in the event it is determined that the mutant ANF proteins protective against stroke have a higher physiological activity than wild type ANF, then ANF mutants having higher ANF activity and molecules that enhance ANF activity are alεo enviεioned for use to treat or prevent stroke or ischemic disease, preferably ischemic stroke. Accordingly, in a specific embodiment of the invention, ANF mutants having increased ANF physiological activity relative to wild type ANF or molecules that enhance ANF activity are administered to treat or prevent stroke or ischemic disease, preferably ischemic stroke. In a more specific embodiment, ANF mutants that have a longer half life in vivo relative to wild type ANF are administered to treat or prevent iεchemic disease, preferably ischemic εtroke. The half-life of a protein is a measurement of protein stability and indicates the time necesεary for a one-half reduction in the concentration of the protein. The half life of a mutant ANF can be determined by any method for meaεuring ANF levelε in εampleε from a subject over a period of time, for example but not limited to, immunoasεayε uεing antirANF antibodieε to measure the mutant ANF levels in sampleε taken over a period of time after adminεtration of the mutant ANF or detection of radiolabeled mutant ANF in εampleε taken from a subject after administration of the radiolabelled mutant ANF. 5.3.1 ISCHEMIC DISEASE In a preferred embodiment, Therapeutics of the invention are administered therapeutically, and preferably, prophylactically, to patients suffering from or in danger of suffering from stroke or an ischemic disease, preferably ischemic stroke, have previously suffered an cerebrovascular event, or exhibit one or more "risk factors" for stroke (i.e., a characteristic, behavior or disorder correlated with increased incidence of stroke) or one or more conditions associated with stroke. See generally, Albers and Cuttler, "Cerebrovascular Diseases", in Scientific American: Medicine, Volume 3 (Chapter 11:X) , eds. Dale and Federman (Scientific American, Inc. 1994) and Barnett, "Cerebral Ischemia and Infarction" in Cecil Textbook of Medicine, edε. Wyngaarden and Smith, (W.B. Saunderε Co. 1988) pp. 2162-2173. A major indication of iεchemic stroke predispoεition iε the incidence of Tranεient Iεchemic Attacks (TIAs) which are brief and non-permanent epiεodeε of neurologic dyεfunction believed to result primarily from thromboembolism. Additionally, a variety of cranial blood vessel disorders can indicate a predisposition for stroke, e.g. atherosclerosis, particularly atheroscleroεis associated with hypertension, diabetes mellituε, or coronary artery or peripheral vaεcular diεeaεe. Non-artherosclerotic angiopathies, particularly those associated with inflammation of the blood vesεelε, εuch as fibromuscular hyperplaεia, dissecting aortic aneurism, Takayasu'ε disease, Mayamaya, allergic vasculitiε, Congophilic angiopathy, vaεculitiε with homocyεtinuria, vasculopathy from drug abuse, vasculitis with Behcets diεeaεe, granulomatous angiitis, tuberculosiε, temporal arteritiε, collagen vascular diseaεe or radiation injury. Trauma to the head and/or neck iε alεo aεεociated with a prediεposition to stroke. Patients suffering from cardiovascular disorders may also be prediεpoεed to stroke. By way of example but not by way of limitation, acute myocardial infarction, heart block, hypertension, atrial fibrillation of any cause, bacterial and nonbacterial thrombotic endocarditis, atrial myxoma- neoplastic tisεue, or implantation of a proεthetic heart valve can increaεe the likelihood that a patient will εuffer an iεchemic εtroke. Certain hematological diseaseε and disorders, particularly those associated with altered blood coagulation, more particularly with thromboseε, alεo can increaεe the risk for stroke. Such hematological diseases include, but are not limited to, deficiencies of antithrombin III, protein C, or protein S, polycythemia vera, sickle cell anemia, diεεeminated intravascular coagulation, thrombotic thrombocytopenic purpura (TTP) , paroxysmal nocturnal hemoglobinuria, hyperviscosity syndromeε, macroglobulmemia, homocyεteinura and lupus. Conditions or states such as shock, surgical anestheεia, pregnancy and post-partum, manifest and occult cancer, and stress due to trauma can also alter blood coagulation and increase the risk of stroke. Other risk factors for stroke include, but are not limited to, ingestion of oral contraceptives, diabetes mellitus, migraine headaches, cigarette smoking and heavy alcohol consumption (although limited quantities may be protective) , high or very low serum cholesterol levels, age, ingestion of substanceε εuch aε amphetamines, cocaine or e- aminocaproic acid, and the presence of antiphospholipid antibodies. In another embodiment, ischemic cardiovascular diseaεeε and diεorders are treated or prevented by administration of a Therapeutic of the invention. In a preferred embodiment, Therapeutics are administered to patients who exhibit one or more "risk factors" for ischemic cardiovascular disease, have a diseaεe or diεorder aεsociated with predispoεition to cardiovaεcular ischemic diseaseε or diεorderε, or have previouεly εuffered from an iεchemic cardiovascular event. See generally, Hutter, "Ischemic Heart Disease: Angina Pectoris" in Scientific American: Medicine (Chapter 1) Dale and Federman, eds. (Scientific American, Inc., 1995). Risk factors and disorders asεociated with increaεed riεk of iεchemic cardiovascular diseaεe include atheroεcleroεiε, angina, hypercholeεterolemia, hypertenεion, obeεity, εmoking cigarettes, and other common risk factors for heart disease. Therapeutics of the invention may be administered either alone or in combination with other therapies, e.g., therapeutics effective to treat or prevent ischemic cerebrovascular or cardiovaεcular diεeaεe. Therapeutics of the invention may also be administered with drugs which treat or ameliorate the effect of certain risk factors, for example but not by way of limitation, therapeutics that reduce cholesterol levelε, treat obeεity, diabeteε mellituε, etc. In a preferred embodiment, a Therapeutic of the invention iε adminiεtered with one or more anti-hypertenεive drug εuch aε, but not limited to, sympatholytics (εuch as propranolol, atenolol, nadolol, labetalol, prazosin, terazosin, doxazoεin, clonidine, guanfacine, methyldopa, reserpine, etc.), angitension inhibitors (such as benazepril, captopril, enalapril, losartan) , calcium channel blockers (εuch aε diltiazem, felodipine, iεradipine, nifedipine, verapamil) , diureticε, e.g., thiazideε (such as bendioflumethiazide, benzthiazide, hydrocholorothiazide, etc.), loop diuretics (such as bumetanide, ethacrynic acid, furosemide, and torεemide) , potaεεium-εparing diureticε (such as amiloride, spironolactone and triametrene) and other diuretics, and vaεodilators (such as hydralazine and minoxidil) . It iε within the εkill of thoεe in the art to monitor and adjuεt the treatment or prophylactic regimen for treating or preventing iεchemic cerebrovaεcular and/or iεchemic cardiovaεcular diεease while treating or preventing other potentially associated diseaseε or disorders, such as hypertension. 5.3.2. GENE THERAPY In a specific embodiment, nucleic acids comprising a sequence encoding a ANF mutant or derivative thereof or an ANF antiεenεe nucleic acid, are adminiεtered by way of gene therapy. Gene therapy referε to therapy performed by the adminiεtration of a nucleic acid to a εubject. In this embodiment of the invention, the nucleic acid produces itε encoded protein or an antiεenεe nucleic acid that mediateε a therapeutic effect. Any of the methodε for gene therapy available in the art can be uεed according to the preεent invention. Exemplary methods are described below. For general reviews of the methods of gene therapy, see Goldspiel et al., Clinical Pharmacy jL2 . :488-505 (1993); Wu and Wu, Biotherapy 3 : 87-95 (1991); Tolstoshev, Ann. Rev. Pharmacol . Toxicol . 3_2.: 573-596 (1993) ; Mulligan, Science 260:926-932 (1993); and Morgan and Anderson, Ann. Rev. Biochem . (62:191-217 (1993); May, TIBTECH 11: 155-215 (1993) ) . Methods commonly known in the art of recombinant DNA technology which can be used are described in Ausubel et al. (eds.), Current Protocols in Molecular Biology (John Wiley & Sons, NY, 1993) ; and Kriegler, Gene Transfer and Expression, A Laboratory Manual (Stockton Press, NY, 1990) . In a preferred aspect, the Therapeutic compriseε an ANF nucleic acid that iε part of an expreεεion vector that expresseε an ANF protein or fragment or chimeric protein, preferably a mutant ANF protein or fragment or chimeric protein, or an ANF antiεenεe nucleic acid thereof in a εuitable host. In particular, such a nucleic acid has a promoter operably linked to the mutant ANF coding region or to a εequence encoding an ANF antiεenεe nucleic acid, said promoter being inducible or constitutive, and, optionally, tissue-specific. In another particular embodiment, a nucleic acid molecule is uεed in which the mutant ANF coding εequences and any other desired sequences are flanked by regions that promote homologous recombination at a deεired site in the genome, thus providing for intrachromosomal expresεion of the mutant ANF nucleic acid (Koller and Smithies, Proc . Natl . Acad . Sci . USA 86:8932-8935 (1989); Zijlstra et al., Nature 342:435-438 (1989)). Delivery of the nucleic acid into a patient may be either direct, in which case the patient is directly exposed to the nucleic acid or nucleic acid-carrying vector, or indirect, in which case, cells are first transformed with the nucleic acid in vitro, then transplanted into the patient. These two approaches are known, respectively, as in vivo or ex vivo gene therapy. In a specific embodiment, the nucleic acid is directly administered in vivo, where it is expressed to produce the encoded product. This can be accomplished by any of numerous methods known in the art, e.g., by constructing it as part of an appropriate nucleic acid expression vector and administering it so that it becomes intracellular, e.g., by infection using a defective or attenuated retroviral or other viral vector (see U.S. Patent No. 4,980,286), or by direct injection of naked DNA, or by use of microparticle bombardment (e.g., a gene gun; Biolistic, Dupont) , or coating with lipids or cell-surface receptors or transfecting agents, encapsulation in liposomes, microparticleε, or microcapεules, or by administering it in linkage to a peptide which is known to enter the nucleus, by administering it in linkage to a ligand subject to receptor-mediated endocytosiε (see e.g., Wu and Wu, J. Biol . Chem . 262:4429-4432 (1987)) (which can be uεed to target cell typeε specifically expresεing the receptors) , etc. In another embodiment, a nucleic acid- ligand complex can be formed in which the ligand comprises a fusogenic viral peptide to disrupt endosomes, allowing the nucleic acid to avoid lyεosomal degradation. In yet another embodiment, the nucleic acid can be targeted in vivo for cell specific uptake and expression, by targeting a specific receptor (see, e.g., PCT Publications WO 92/06180 dated April 16, 1992 (Wu et al.); WO 92/22635 dated December 23, 1992 (Wilson et al.); WO92/20316 dated November 26, 1992 (Findeis et al.); W093/14188 dated July 22, 1993 (Clarke et al.), WO 93/20221 dated October 14, 1993 (Young)). Alternatively, the nucleic acid can be introduced intracellularly and incorporated within hoεt cell DNA for expression, by homologous recombination (Koller and Smithies, Proc . Natl . Acad . Sci . USA 8j5: 8932-8935 (1989); Zijlstra et al. , Nature 342:435-438 (1989)). In a εpecific embodiment, a viral vector that containε the mutant ANF nucleic acid or codeε for ANF antiεenεe nucleic acid iε uεed. For example, a retroviral vector can be used (see Miller et al., Meth . Enzymol . 217:581-599 (1993)). These retroviral vectors have been modified to delete retroviral sequenceε that are not neceεsary for packaging of the viral genome and integration into host cell DNA. The ANF nucleic acid to be uεed in gene therapy iε cloned into the vector, which facilitateε delivery of the gene into a patient. More detail about retroviral vectors can be found in Boesen et al., Biotherapy 6.:291-302 (1994), which describeε the uεe of a retroviral vector to deliver the mdrl gene to hematopoietic εtem cellε in order to make the stem cells more resiεtant to chemotherapy. Other referenceε illustrating the use of retroviral vectors in gene therapy are: Clowes et al., J. Clin . Invest . £3_: 644-651 (1994); Kiem et al., Blood 3:1467-1473 (1994); Salmons and Gunzberg, Human Gene Therapy 4 . : 129-141 (1993); and Groεsman and Wilεon, Curr. Opin . in Genetics and Devel . 3_:110-114 (1993). Adenoviruεeε are other viral vectors that can be used in gene therapy. Adenoviruseε are especially attractive vehicles for delivering genes to respiratory epithelia. Adenoviruses naturally infect reεpiratory epithelia where they cauεe a mild diεeaεe. Other targets for adenovirus- based delivery systems are liver, the central nervous syεte , endothelial cells, and muscle. Adenoviruseε have the advantage of being capable of infecting non-dividing cellε. Kozarεky and Wilson, Curr. Opin . in Genetics and Devel . 5 3 . : 499-503 (1993) present a review of adenovirus-baεed gene therapy. Bout et al., Human Gene Therapy 5_:3-10 (1994) demonεtrated the use of adenovirus vectors to transfer genes to the respiratory epithelia of rhesus monkeys. Other instanceε of the uεe of adenoviruses in gene therapy can be 10 found in Rosenfeld et al., Science 252:431-434 (1991); Roεenfeld et al.. Cell 68 . : 143-155 (1992); and Maεtrangeli et al., J. Clin . Invest . 91:225-234 (1993). Adeno-aεεociated virus (AAV) has also been proposed for use in gene therapy (Walsh et al., Proc . Soc . Exp . Biol . Med . 15 204:289-300 (1993). Another approach to gene therapy involveε tranεferring a gene to cells in tissue culture by such methods as electroporation, lipofection, calcium phosphate mediated transfection, or viral infection. Usually, the method of 20 tranεfer includeε the tranεfer of a εelectable marker to the cells. The cells are then placed under selection to isolate those cells that have taken up and are expresεing the tranεferred gene. Thoεe cellε are then delivered to a patient. 25 In thiε embodiment, the nucleic acid iε introduced into a cell prior to administration in vivo of the resulting recombinant cell. Such introduction can be carried out by any method known in the art, including but not limited to transfection, electroporation, microinjection, infection with 30 a viral or bacteriophage vector containing the nucleic acid sequenceε, cell fuεion, chromoεome-mediated gene transfer, microcell-mediated gene transfer, spheroplast fuεion, etc. Numerouε techniqueε are known in the art for the introduction of foreign geneε into cellε (εee e.g., Loeffler and Behr, 35 Meth . Enzymol . 217:599-618 (1993); Cohen et al., Meth . Enzymol . 217:618-644 (1993); Cline, Pharmac. Ther. 29:69-92 (1985)) and may be used in accordance with the present invention, provided that the neceεεary developmental and physiological functions of the recipient cells are not disrupted. The technique should provide for the stable tranεfer of the nucleic acid to the cell, εo that the nucleic acid iε expreεsible by the cell and preferably heritable and expresεible by itε cell progeny. The reεulting recombinant cellε can be delivered to a patient by variouε methodε known in the art. In a preferred embodiment, epithelial cellε are injected, e.g., subcutaneously. In another embodiment, recombinant skin cells may be applied as a skin graft onto the patient. Recombinant blood cells (e.g., hematopoietic stem or progenitor cellε) are preferably adminiεtered intravenously. The amount of cells enviεioned for uεe dependε on the desired effect, patient state, etc., and can be determined by one skilled in the art. Cells into which a nucleic acid can be introduced for purposeε of gene therapy encompass any desired, available cell type, and include but are not limited to epithelial cells, endothelial cells, keratinocytes, fibroblasts, muscle cells, hepatocytes; blood cells such as T lymphocytes, B lymphocytes, monocytes, macrophages, neutrophilε, eosinophilε, megakaryocyteε, granulocyteε; variouε εtem or progenitor cellε, in particular hematopoietic εtem or progenitor cellε, e.g., as obtained from bone marrow, umbilical cord blood, peripheral blood, fetal liver, etc. In a preferred embodiment, the cell used for gene therapy is autologouε to the patient. In an embodiment in which recombinant cellε are uεed in gene therapy, a mutant ANF nucleic acid or nucleic acid encoding an ANF antisense nucleic acid is introduced into the cells such that it is expresεible by the cells or their progeny, and the recombinant cells are then administered in vivo for therapeutic effect. In a specific embodiment, stem or progenitor cells are used. Any stem and/or progenitor cells which can be isolated and maintained in vitro can potentially be used in accordance with this embodiment of the present invention. Such stem cells include but are not limited to hematopoietic stem cells (HSC) , stem cells of epithelial tisεueε such as the εkin and the lining of the gut, embryonic heart muεcle cells, liver stem cellε (PCT Publication WO 94/08598, dated April 28, 1994), and neural εtem cells (Stemple and Anderson, Cell 7.1:973-985 (1992)). Epithelial stem cells (ESCs) or keratinocytes can be obtained from tissues such as the skin and the lining of the gut by known procedureε (Rheinwald, Meth . Cell Bio . 21A:229 (1980)). In εtratified epithelial tissue such aε the εkin, renewal occurε by mitoεiε of εtem cellε within the germinal layer, the layer cloεeεt to the baεal lamina. Stem cellε within the lining of the gut provide for a rapid renewal rate of thiε tissue. ESCs or keratinocyteε obtained from the skin or lining of the gut of a patient or donor can be grown in tissue culture (Rheinwald, Meth . Cell Bio . 21A:229 (1980); Pittelkow and Scott, Mayo Clinic Proc . j5JL:771 (1986,)). If the ESCs are provided by a donor, a method for suppresεion of hoεt verεuε graft reactivity (e.g., irradiation, drug or antibody administration to promote moderate immunosuppreεεion) can also be used. With respect to hematopoietic stem cellε (HSC) , any technique that provides for the isolation, propagation, and maintenance in vitro of HSC can be uεed in thiε embodiment of the invention. Techniqueε by which thiε may be accompliεhed include (a) the iεolation and eεtabliεhment of HSC cultures from bone marrow cells isolated from the future host, or a donor, or (b) the use of previously established long-term HSC cultures, which may be allogeneic or xenogeneic. Non- autologous HSC are used preferably in conjunction with a method of suppressing transplantation immune reactions of the future host/patient. In a particular embodiment of the preεent invention, human bone marrow cellε can be obtained from the poεterior iliac creεt by needle aεpiration (see, e.g., Kodo et al., J * . Clin . Invest . 23:1377-1384 (1984)). In a preferred embodiment of the preεent invention, the HSCε can be made highly enriched or in εubεtantially pure form. Thiε enrichment can be accompliεhed before, during, or after long- term culturing, and can be done by any techniques known in the art. Long-term cultures of bone marrow cells can be established and maintained by using, for example, modified Dexter cell culture techniques (Dexter et al., J. Cell Physiol . 91:335 (1977)) or Witlock-Witte culture techniques (Witlock and Witte, Proc . Natl . Acad . Sci . USA 79:3608-3612 (1982)) . In a specific embodiment, the nucleic acid to be introduced for purposes of gene therapy comprises an inducible promoter operably linked to the coding region, such that expression of the nucleic acid is controllable by controlling the presence or absence of the appropriate inducer of transcription. Additional methods that can be adapted for use to deliver a nucleic acid encoding a ANF protein or functional derivative thereof are described in Section 5.6. 5.3.3. ANTIBODIES In one embodiment, aε discuεεed hereinabove, antibodieε that bind ANF proteinε, ANF protein fragmentε or other derivatives, or analogs thereof are used to treat or prevent stroke or ischemic diseaεe, preferably ischemic stroke. Anti-ANF antibodieε can alεo be used in the diagnostic, prognostic and screening methods of the invention, e.g. as described in Section 5.4, infra . Such antibodieε include, but are not limited to, polyclonal, monoclonal, chimeric, single chain, Fab fragments, and an Fab expression library. In a specific embodiment, antibodies to a human ANF protein are produced. In another specific embodiment, antibodies that reduce or inhibit ANF activity in vitro and/or in vivo, are provided. Various procedures known in the art may be used for the production of polyclonal antibodies to an ANF protein or derivative or analog. In a particular embodiment, rabbit polyclonal antibodies to an epitope of an ANF protein (e.g. the protein of amino acid sequences SEQ ID NOS: 1 and 4 , or encoded by the nucleotide sequences of SEQ ID NOS: 3 and 6, or a subsequence thereof) , can be obtained. For the production of antibody, various host animals can be immunized by injection with the native ANF protein, or a synthetic version, or derivative (e.g., fragment) thereof, including but not limited to rabbits, mice, rats, etc. Various adjuvants may be used to increase the immunological reεponεe, depending on the host species, and including but not limited to Freund's (complete and incomplete) , mineral gels εuch aε aluminum hydroxide, εurface active εubεtanceε such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanins, dinitrophenol, and potentially useful human adjuvants such as BCG (bacille Calmette-Guerin) and corynebacterium parvu . For preparation of monoclonal antibodies directed toward an ANF protein sequence or analog thereof, any technique which provides for the production of antibody molecules by continuous cell lines in culture may be used. For example, the hybridoma technique originally developed by Kohler and Milstein (Nature 256:495-497 (1975)), as well as the trioma technique, the human B-cell hybridoma technique (Kozbor et al., Immunology Today 4 . :72 (1983)), and the EBV-hybridoma technique to produce human monoclonal antibodies (Cole et al., in Monoclonal Antibodies and Cancer Therapy, Alan R. Lisε, Inc., (1985) pp. 77-96). In an additional embodiment of the invention, monoclonal antibodies can be produced in germ-free animals utilizing recent technology (PCT/US90/02545) . According to the invention, human antibodieε may be uεed and can be obtained by uεing human hybridomas (Cote et al., Proc . Natl . Acad . Sci . U.S .A. £0:2026-2030 (1983)) or by transforming human B cells with EBV virus in vitro (Cole et al., in Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, (1985) pp. 77-96). In fact, according to the invention, techniques developed for the production of "chimeric antibodies" (Morrison et al., Proc . Natl . Acad . Sci . U.S.A. 1:6851-6855 (1984); Neuberger et al., Nature 312:604-608 (1984); Takeda et al., Nature 314:452-454 (1985)) by splicing the genes from a mouse antibody molecule specific for ANF together with genes from a human antibody molecule of appropriate biological activity can be used; such antibodies are within the scope of this 5 invention. According to the invention, techniques described for the production of εingle chain antibodies (U.S. Patent 4,946,778) can be adapted to produce ANF-specific single chain .antibodieε. An additional embodiment of the invention 0 utilizeε the techniques described for the construction of Fab expreεεion libraries (Huse et al., Science 246:1275-1281 (1989)) to allow rapid and easy identification of monoclonal Fab fragments with the desired specificity for ANF proteins, derivativeε, or analogε. 5 Antibody fragmentε which contain the idiotype of the molecule can be generated by known techniqueε. For example, such fragmentε include but are not limited to: the F(ab') 2 fragment which can be produced by pepεin digestion of the antibody molecule; the Fab' fragments which can be generated 0 by reducing the diεulfide bridges of the F(ab') 2 fragment, the Fab fragments which can be generated by treating the antibody molecule with papain and a reducing agent, and Fv fragmentε. In the production of antibodieε, εcreening for the deεired antibody can be accompliεhed by techniques known in 5 the art, e.g. ELISA (enzyme-linked immunosorbent assay) . For example, to select antibodies which recognize a specific portion of an ANF protein, one may asεay generated hybridomaε for a product which bindε to an ANF fragment containing εuch portion. For εelection of an antibody that can reduce or 30 inhibit ANF activity, one can aεsay the antibody in any of the assays for ANF activity described in Section 5.7 infra . 5.3.4. THERAPEUTIC USE OF ANF ANTISENSE NUCLEIC ACIDS 3 _5_ In a specific embodiment, as described hereinabove, ANF function is reduced or inhibited by ANF antisenεe nucleic acids, to treat or prevent stroke or ischemic disease, preferably ischemic stroke. The present invention provides the therapeutic or prophylactic uεe of nucleic acidε of at leaεt εix nucleotides that are antisenεe to a gene or cDNA encoding ANF or a portion thereof. An ANF "antiεenεe" nucleic acid aε used herein refers to a nucleic acid capable of hybridizing to a portion of an ANF RNA (preferably mRNA) by virtue of some sequence complementarily. The antisense nucleic acid may be complementary to a coding and/or noncoding region of an AN mRNA. Because ANF iε initially expreεεed aε part the proANP hormone, "ANF mRNA" includeε mRNA encoding the proANP hormone; and, thuε, "ANF antiεense nucleic acids" include nucleic acids that are capable of hybridizing to any portion of the proANP mRNA, including portions of the proANP mRNA coding for the other three hormoneε derived from proANP by proteolytic cleavage. Such antisense nucleic acids have utility as Therapeuticε that reduce or inhibit ANF function, and can be uεed in the treatment or prevention of disorders as deεcribed supra. The ANF antisense nucleic acids are of at least εix nucleotideε and are preferably oligonucleotideε (ranging from 6 to about 150 nucleotideε, or more preferably 6 to 50 nucleotides) . In specific aspects, the oligonucleotide is at least 10 nucleotides, at least 15 nucleotides, at least 100 nucleotideε, or at leaεt 125 nucleotides. The oligonucleotides can be DNA or RNA or chimeric mixtures or derivatives or modified versions thereof, single-stranded or double-stranded. The oligonucleotide can be modified at the base moiety, sugar moiety, or phosphate backbone. The oligonucleotide may include other appending groupε εuch aε peptideε, or agents facilitating transport across the cell membrane (see, e.g., Letsinger et al. , Proc . Natl . Acad . Sci . U.S.A . 86-6553-6556 (1989); Lemaitre et al., Proc. Natl . Acad . Sci . C7.S.A._8_4: 648-652 (1987); PCT Publication No. WO 88/09810, published December 15, 1988) or blood-brain barrier (see, e.g., PCT Publication No. WO 89/10134, publiεhed April 25, 1988) , hybridization-triggered cleavage agentε (see, e.g., Krol et al., BioTechniques .5:958-976 (1988)) or intercalating agents (see, e .g. , Zon, Pharm . Res . 5:539-549 (1988)). The ANF antisenεe nucleic acid is preferably an oligonucleotide, more preferably of single-stranded DNA. In a preferred aspect, the oligonucleotide compriseε a sequence antisense to a portion of human ANF. The oligonucleotide may be modified at any position on its εtructure with substituentε generally known in the art. The ANF antiεenεe oligonucleotide may compriεe at leaεt one modified baεe moiety which iε εelected from the group including but not limited to 5-fluorouracil, 5-bromouracil, 5-chlorouracil, 5-iodouracil, hypoxanthine, xantine, 4-acetylcytoεine, 5- (carboxyhydroxylmethyl) uracil, 5-carboxymethylaminomethyl-2-thiouridine, 5-carboxymethylaminomethyluracil, dihydrouracil, beta-D- galactosylqueosine, inoεine, N6-isopentenyladenine, 1-methylguanine, 1-methylinosine, 2,2-dimethylguanine, 2-methyladenine, 2-methylguanine, 3-methylcytosine, 5-methylcytosine, N6-adenine, 7-methylguanine, 5-methylaminomethyluracil, 5-methoxyaminomethyl-2-thiouracil, beta-D-mannosylqueoεine, 5 ' -methoxycarboxymethyluracil, 5-methoxyuracil, 2-methylthio-N6-iεopentenyladenine, uracil-5-oxyacetic acid (v) , wybutoxoεine, pεeudouracil, queoεine, 2-thiocytosine, 5-methyl-2-thiouracil, 2-thiouracil, 4-thiouracil, 5-methyluracil, uracil- 5-oxyacetic acid methylester, uracil-5-oxyacetic acid (v) , 5-methyl-2-thiouracil, 3- (3-amino-3-N-2-carboxypropyl) uracil, (acp3)w, and 2,6-diaminopurine. In another embodiment, the oligonucleotide compriseε at leaεt one modified sugar moiety selected from the group including but not limited to arabinoεe, 2-fluoroarabinoεe, xyluloεe, and hexoεe. In yet another embodiment, the oligonucleotide comprises at least one modified phosphate backbone selected from the group consisting of a phosphorothioate, a phosphorodithioate, a phosphoramidothioate, a phosphoramidate, a phosphordiamidate, a methylphosphonate, an alkyl phoεphotriester, and a formacetal or analog thereof. In yet another embodiment, the oligonucleotide is an α-anomeric oligonucleotide. An α-anomeric oligonucleotide forms specific double-stranded hybrids with complementary RNA in which, contrary to the usual /3-unitε, the εtrandε run parallel to each other (Gautier et al., Nucl . Acids Res . 15:6625-6641 (1987)). The oligonucleotide may be conjugated to another molecule, e.g., a peptide, hybridization triggered cross- linking agent, transport agent, hybridization-triggered cleavage agent, etc. Oligonucleotides of the invention may be εyntheεized by εtandard methodε known in the art, e.g. by uεe of an automated DNA εynthesizer (εuch aε are commercially available from Bioεearch, Applied Bioεyεtemε, etc.). As examples, phoεphorothioate oligonucleotideε may be synthesized by the method of Stein et al. (Nucl . Acids Res . 16:3209 (1988)), methylphosphonate oligonucleotides can be prepared by use of controlled pore glass polymer supportε (Sarin et al., Proc. Natl . Acad . Sci . U.S .A. 85:7448-7451 (1988)), etc. In a specific embodiment, the ANF antisenεe oligonucleotide compriεeε catalytic RNA, or a ribozyme (εee, e.g., PCT International Publication WO 90/11364, publiεhed October 4, 1990; Sarver et al., Science 247:1222-1225 (1990)). Xn another embodiment, the oligonucleotide iε a 2'- 0-methylribonucleotide (Inoue et al., Nucl . Acids Res . JL5:6131-6148 (1987)), or a chimeric RNA-DNA analogue (Inoue et al., FEBS Lett . 215:327-330 (1987)). In an alternative embodiment, the ANF antiεenεe nucleic acid of the invention iε produced intracellularly by transcription from an exogenous sequence. For example, a vector can be introduced in vivo such that it is taken up by a cell, within which cell the vector or a portion thereof is transcribed, producing an antisense nucleic acid (RNA) of the invention. Such a vector would contain a sequence encoding the ANF antisense nucleic acid. Such a vector can remain episomal or become chro osomally integrated, as long as it can be transcribed to produce the desired antisense RNA. Such vectorε can be constructed by recombinant DNA technology methods standard in the art. Vectors can be plasmid, viral, or others known in the art, used for replication and expresεion in mammalian cellε. Expreεεion of the sequence encoding the ANF antiεenεe RNA can be by any promoter known in the art to act in mammalian, preferably human, cellε. Such promoters can be inducible or constitutive. Such promoterε include but are not limited to: the SV40 early promoter region (Bernoiεt and Chambon, 1981, Nature 290:304- 310), the promoter contained in the 3' long terminal repeat of Rouε εarcoma viruε (Yama oto et al., 1980, Cell 22:787- 797), the herpeε thymidine kinaεe promoter (Wagner et al., 1981, Proc. Natl. Acad. Sci. U.S.A. 78:1441-1445), the regulatory εequenceε of the metallothionein gene (Brinεter et al., 1982, Nature 296:39-42), etc. The antiεenεe nucleic acidε of the invention compriεe a sequence complementary to at least a portion of an RNA transcript of an ANF gene, preferably a human ANF gene. However, absolute complementarily, although preferred, is not required. A sequence "complementary to at least a portion of an RNA," as referred to herein, means a sequence having sufficient complementarily to be able to hybridize with the RNA, forming a stable duplex; in the case of double-stranded ANF antisenεe nucleic acidε, a single strand of the duplex DNA may thus be tested, or triplex formation may be assayed. The ability to hybridize will depend on both the degree of complementarily and the length of the antisense nucleic acid. Generally, the longer the hybridizing nucleic acid, the more base mismatches with a an ANF RNA it may contain and still form a stable duplex (or triplex, aε the caεe may be) . One skilled in the art can aεcertain a tolerable degree of miεmatch by uεe of εtandard procedureε to determine the melting point of the hybridized complex. The invention further provideε pharmaceutical compoεitionε compriεing an effective amount of the ANF antisense nucleic acids of the invention in a pharmaceutically acceptable carrier, as described infra . In a specific embodiment, pharmaceutical compositions comprising ANF antisenεe nucleic acids are administered via lipoεomeε, microparticleε, or microcapεuleε. In various embodiments of the invention, it may be useful to use εuch compoεitionε to achieve εustained release of the ANF antisenεe nucleic acids. The amount of ANF antisenεe nucleic acid which will be effective in the treatment or prevention of iεchemic diεeaεe will depend on the nature of the diεeaεe, and can be determined by εtandard clinical techniqueε. Where possible, it is desirable to determine the antiεenεe cytotoxicity in cellε in vitro , and then in uεeful animal model εyεtems prior to testing and uεe in humanε. Additional methods that can be adapted for uεe to deliver a ANF antiεenεe nucleic acid are described in Section 5.6 infra . 5.4. METHODS OF DIAGNOSIS. PROGNOSIS AND SCREENING The present invention also relates to methods of diagnosis, prognosis and screening for stroke or ischemic disease, preferably ischemic stroke, including but not limited to in those subjectε having iεchemic disease or stroke, having previouεly εuffered an cerebrovascular event or exhibit one or more "risk factors" for stroke or one or more conditions associated with stroke. In a preferred aspect, the invention relates to methods for screening for an allele protective againεt stroke. In one embodiment, anti-ANF-antibodies are uεed to detect and quantitate mutant ANF levelε in one or more tissues (e .g. , blood) of a subject in immunoassays. In particular, εuch an immunoaεεay is carried out by a method comprising contacting a sample derived from a patient with an anti-ANF antibody under conditions such that immunospecific binding can occur, and detecting or meaεuring the amount of any immunoεpecific binding by the antibody. The particular amino acid deletion, insertion or substitution in the mutant ANF can change the epitope recognized by a specific anti-(wild type) ANF antibody εuch that antibody bindε the mutant ANF to a lesser extent or not at all. Additionally, antibodies can be raised (e.g. as described in Section 5.3.3 supra) against the mutant ANF protein, or portion thereof, that bind specifically to the particular mutant ANF, but not the wild type ANF (aε determined by the in vitro immumoaεεayε described below) . These specific anti- mutant ANF antibodies can be used to detect the presence of ANF mutants by measuring the immunospecific binding by the anti-mutant ANF antibodies and, optionally, lack of immunospecific binding by the anti-(wild type) ANF antibodieε. Additionally, ANF proteinε having deletion or insertion mutations can be detected by an increaεe or decreaεe in protein εize by, for example, but not limited to, weεtern blot analyεiε uεing an anti-ANF antibody that recognizeε the mutant and wild-type ANF. The immunoassayε which can be used include but are not limited to competitive and non-competitive assay systems using techniques such as western blots, radioimmunoassays, ELISA (enzyme linked immunoεorbent aεεay) , "εandwich" immunoasεays, immunoprecipitation asεayε, precipitin reactionε, gel diffuεion precipitin reactions, immunodiffusion asεayε, agglutination assays, complement- fixation asεayε, immunoradiometric aεsays, fluorescent immunoasεayε, protein A immunoaεεayε, to name but a few. In a εpecific embodiment, methodε of diagnoεiε, prognoεiε and screening by detecting mutant ANF alleles in genomic DNA or mRNA (i.e. genetic screening) are provided. Preferably, mutant alleles known to be protective for stroke are detected in genomic DNA or cDNA derived from mRNA from a subject. In a preferred embodiment, methods for detecting an amino acid subεtitution at the poεition corresponding to amino acid 1 of the rat or human ANF amino acid sequence as depicted in Figures 2 or 5, respectively (SEQ ID N0S:1 or 4, respectively) are provided for asεeεεing an allele protective for stroke. The mutant ANF alleles can be detected by any method known in the art for detecting mutations in genomic DNA. By way of example but not by way of limitation, DNA hybridization methods (e.g. Southern Blotting) , RFLP mapping, PCR based methods, etc. can be used with nucleic acid probes complementary to the mutation and to the correεponding poεition in the wild type sequence. In a preferred embodiment, allele-specific PCR (ASP) can be uεed to detect mutant ANF alleles. In ASP, a target DNA is preferentially amplified if it is completely complementary to the 3' end of a PCR amplification primer. The 3' end of the primer should terminate at or within one or two bases of a known mutation site in the ANF gene (target DNA) to which it has a complementary sequence. Under the appropriate reaction conditions, the target DNA is not amplified if there is a base mismatch (e.g., a nucleotide substitution caused by a mutation) or a small deletion or insertion, at the 3' end of the primer (Okayama et al. J. Lab . Clin . Med. 114:105-113 (1989); Sommer et al., BioTechniques 12.:82-87 (1992). Thus, ASP can be used to detect the presence or abεence of at leaεt a εingle miεmatch between the primer εequence that iε complementary to the preεelected target εequence and a nucleic acid in the sample; amplification indicates the absence of such a single miεmatch. Preferred ASP primers for detecting a mutation in the position corresponding to amino acid 1 of rat ANF include 5'-AGATGGAGGTGCTCTCGGGCGCA-3 ' (SEQ ID NO: 11). The wild type locus can be detected using a primer 5'-AGATGGAGGTGCTCTCGGGCGCG-3' (SEQ ID NO: 12). Preferred ASP primers for detecting a mutation in the position corresponding to amino acid 1 of human ANF include 5'-AGAGATGGAGGTGCCCTCGGGCGGA-3' (SEQ ID NO: 13). The wild type locus can be detected using a primer 5' -AGAGATGGAGGTGC CCTCGGGCGGG-3 ' (SEQ ID NO: 14). Additionally, where the mutant is a deletion or insertion mutation, mutant ANF alleles can be detected by asεaying for an increaεe or decreaεe in the length of the ANF nucleotide εequence or portion thereof. The increaεe or decreaεe in length can be detected by any method known in the art for meaεuring the length of nucleic acidε, for example, but not limited to, by amplification of a specific fragment of the ANF sequence from the subject to be diagnosed or screened and from a standard or control sample and comparison of the length of the fragmentε by any size fractionation method, such as but not limited to, denaturing polyacrylamide gel electrophoresis. Kits for diagnoεtic or εcreening uεe are alεo provided that comprise in one or more containers an anti-ANF antibody or anti-ANF mutant antibody, and, optionally, a labeled binding partner to the antibody. Alternatively, the anti-ANF antibody or anti-ANF mutant antibody can be labeled (with a detectable marker, e.g., a chemiluminescent, enzymatic, fluoreεcent, or radioactive moiety) . A kit iε alεo provided that comprises in one or more containers a nucleic acid probe capable of hybridizing to ANF RNA or, preferably, capable of specifically hybridizing to mutant ANF. In a specific embodiment, a kit can comprise in one or more containers a pair of primers (e . g. , each in the size range of 6-30 nucleotides) that are capable of priming amplification [e.g., by polymerase chain reaction (see e.g., Innis et al., PCR Protocols (Academic Preεε, Inc., San Diego, CA (1990)), ligaεe chain reaction (see EP 320,308) use of Qβ replicase, cyclic probe reaction, or other methods known in the art] under appropriate reaction conditionε of at least a portion of a ANF nucleic acid. A kit can optionally further comprise in a container a predetermined amount of a purified ANF protein or nucleic acid, e.g., for use aε a εtandard or control. 5.5. ASSAYS FOR ANF MUTANTS AND MODULATORS OF ANF A variety of methods are available in the art for assaying the activity of ANF mutants, derivatives, analogε, fragments and homologs of ANF mutants, and nucleic acids encoding the ANF mutants and derivatives, analogs and fragments thereof. Methodε are also available for the screening of putative ANF modulators (e.g. ANF agoniεtε, antagonists and inhibitors) . Such modulators of ANF activity include, but are not limited to, ANF antisense nucleic acids, anti-ANF antibodies, and competitive inhibitors of ANF for binding to the ANF receptor. In vitro methods for assaying ANF mutant protein, and derivatives, fragments, homologs and analogs thereof, the nucleic acids encoding these ANF mutants, and putative modulators of ANF (e.g. agoniεtε, antagoniεtε or inhibitorε of ANF activity) include, but are not limited to, ANF receptor binding assayε, such as those described by Vesely et al. (Renal Phys . & Biochem . 15:23-32 (1992)), Iwashina et al. (J * . Biochem . 115563-567 (1994)), de Leon et al. (J. Hypertens . 12:539-548 (1994)), He et al. (Bioconjugate Chem . 6:541-548 (1995)), and Chang et al. (Curr. Eye Res . 15:137- 143 (1996)); measurement of changes in cGMP concentrations in cells having ANF receptors, e.g., by methods described by Schulz et al. ( Cell 58:1155-1162 (1989)) and Wedel et al. (Proc . Natl . Acad . Sci . U.S .A. 21:459-462 (1997)); and changes in intracellular Ca + resulting from ANF receptor signalling in response to ANF binding, e.g. as deεcribed by Naεcimento-Gomeε et al. (Brazil . J. of Med. & Biol . Res . £8.: 609-613 (1995)). However, any meaεurement of ANF receptor activity elicited by ANF binding can be used to asεay ANF activity in vitro. The activity of the ANF mutantε, derivatives, fragments, analogs and homologs of ANF mutants, the nucleic acids encoding these ANF mutants, and derivativeε, fragments, analogs and homologs of ANF mutants, and putative modulators of ANF activity can alεo be teεted in vivo. For example, infuεion of ANF in humanε causes significant increases in cGMP levels in plasma and urine (Vesely et al., Am. J. Med . Sci . 310:143-149 (1995); Vesely et al., Metabolism: Clin . & Exp. 4_5:315-319 (1996)). Administration of ANF to humans also elicits significant diuresis and reduction in blood pressure (Vesely et al., .Life Sciences 59:243-254 (1996)); similar effects have been observed in rats (Garcia et al., Hypertension 13.:567-574 (1989)). Accordingly, the mutant ANF proteins and nucleic acids, and derivativeε, analogε, fragmentε, and homologε thereof, and putative ANF modulatorε can be aεεayed by administration of the test compound to a teεt animal, preferably a non-human teεt animal εuch as a rat or mouse, and then measurement of the one or more of the physiological parameters deεcribed above, e.g. cGMP levelε in urine and/or plaεma, diuretic effect, decreaεe in blood preεsure, etc. In a preferred embodiment, rats derived from crosses with SHRSP animals are used to aεεay for ANF activity or ANF modulator activity. For example, rats that have the stroke- prediεpoεing locuε on chromosome 1 and lack the stroke- protective locus on chromoεome 5 that mapε to the ANF gene (and optionally the other stroke-protective locus on chromosome 4) can be used to screen for ANF mutants and putative ANF antagonists. In particular, nucleic acids containing the nucleotide sequence encoding an ANF mutant can be introduced into the rats having the chromoεome 1 εtroke prediεpoεing locuε but not the εtroke protective loci. ANF mutants useful for treatment and prevention of stroke would increase stroke latency when either administered or expressed transgenically in the εtroke prone ratε lacking the two protective loci and fed a high salt diet. In one embodiment, a putative modulator of ANF activity or of latency or predispoεition to stroke is screened by (a) administering a putative modulator of ANF activity to an animal prone to stroke, and (b) measuring one or more phyεiological parameters asεociated with ANF activity, in which a change in εaid one or more parameterε relative to an animal not administered the putative modulator indicates that the putative modulator modulates ANF activity or latency or predisposition to stroke. In a specific embodiment, the animal prone to stroke iε fed a high εalt diet. In a preferred embodiment, the physiological parameter is stroke latency. Additionally, ANF modulators can be screened using a recombinant test animal which expresses an ANF transgene or expresseε ANF under the control of a promoter that iε not the native ANF gene promoter at an increaεed level relative to a wild type test animal. Another embodiment provides a method for εcreening an ANF mutant for a change in ANF activity comprising (a) administering the ANF mutant to a test animal prone to stroke; and (b) measuring stroke latency in the teεt animal in which εtroke latency is indicative of ANF activity. In a specific embodiment, a recombinant test animal which expresses an ANF transgene or expreεses ANF under the control of a promoter that iε not the native ANF gene promoter at an increaεed level relative to a wild type teεt animal iε uεed to εcreen ANF mutantε for a change in ANF activity. In yet another embodiment, a method for εcreening for a modulator of ANF activity or of latency or prediεposition to stroke is provided which comprises measuring stroke latency in a εtroke prone animal that recombinantly expreεεeε a putative modulator of ANF activity, in which a change in εtroke latency relative to an analogouε stroke prone animal that does not recombinantly express the putative modulator indicates that the putative modulator modulates ANF activity or latency or predisposition to stroke. In another embodiment, a method is provided for screening an ANF mutant for an effect on latency or predisposition to stroke comprising measuring stroke latency in a εtroke prone animal that recombinantly expresses an ANF mutant, in which a change in stroke latency relative to an analogous stroke prone animal that does not recombinantly express the ANF mutant indicates that the ANF mutant has an effect on latency or predisposition to εtroke. In a preferred embodiment, an ANF mutant is screened for an increase in stroke latency or a decrease in predispoεition to εtroke. 5.6. PHARMACEUTICAL COMPOSITIONS The invention provideε methodε of treatment and prophylaxis by administering to a subject of an effective amount of a Therapeutic of the invention. In a preferred aspect, the Therapeutic is subεtantially purified. The εubject iε preferably an animal, including but not limited to animals such as cows, pigs, horses, chickens, cats, dogs, etc., and is preferably a mammal, and most preferably human. In a specific embodiment, a non-human mammal is the subject. Formulations and methodε of administration that can be employed when the Therapeutic compriseε a nucleic acid are deεcribed in Sectionε 5.3.2 and 5.3.4 above; additional appropriate formulationε and routeε of adminiεtration can be εelected from among those described hereinbelow. Various delivery systems are known and can be used to administer a Therapeutic of the invention, e.g., encapsulation in liposomes, microparticleε, microcapεuleε, recombinant cellε capable of expreεεing the Therapeutic, receptor-mediated endocytoεis (see, e.g., Wu and Wu, J. Biol . Chem . 262:4429-4432 (1987)), construction of a Therapeutic nucleic acid aε part of a retroviral or other vector, etc. Methodε of introduction include but are not limited to intradermal, intramuscular, intraperitoneal, intravenous, subcutaneous, intranasal, epidural, and oral routes. The compounds may be administered by any convenient route, for example by infusion or bolus injection, by absorption through epithelial or mucocutaneous liningε (e.g., oral mucoεa, rectal and intestinal mucosa, etc.) and may be adminiεtered together with other biologically active agentε. Adminiεtration can be εystemic or local. In addition, it may be desirable to introduce the pharmaceutical compositions of the invention into the central nervous system by any suitable route, including intraventricular and intrathecal injection; mtraventricular injection may be facilitated by an intraventricular catheter, for example, attached to a reεervoir, εuch as an Ommaya reservoir. Pulmonary administration can alεo be employed, e.g., by uεe of an inhaler or nebulizer, and formulation with an aeroεolizing agent. In a εpecific embodiment, it may be desirable to administer the pharmaceutical compositions of the invention locally to the area in need of treatment; this may be achieved by, for example, and not by way of limitation, local infusion during surgery, topical application, e.g., in conjunction with a wound dresεing after εurgery, by injection, by means of a catheter, by means of a suppository, or by means of an implant, εaid implant being of a porous, non-porous, or gelatinous material, including membraneε, such as sialaεtic membranes, or fibers. In another embodiment, the Therapeutic can be delivered in a veεicle, in particular a lipoεome (see Langer, Science 249:1527-1533 (1990); Treat et al., in Lipoεomeε in the Therapy of Infectiouε Diseaεe and Cancer, Lopez-Bereεtein and Fidler (edε.), Liεε, New York, pp. 353-365 (1989); Lopez-Berestein, ibid. , pp. 317-327; see generally iJbid.) In yet another embodiment, the Therapeutic can be delivered in a controlled release system. In one embodiment, a pump may be used (see Langer, supra ; Sefton, CRC Crit . Ref . Biomed . Eng. 14:201 (1987); Buchwald et al., Surgery 88:507 (1980); Saudek et al., N. Engl . J. Med. 321:574 (1989)). In another embodiment, polymeric materials can be used (see Medical Applications of Controlled Release, Langer and Wise (eds.), CRC Preε., Boca Raton, Florida (1974); Controlled Drug Bioavailability, Drug Product Design and Performance, Smolen and Ball (eds.), Wiley, New York (1984); Ranger and Peppas, J. Macromol . Sci . Rev. Macromol . Chem . .23.: 61 (1983); see also Levy et al.. Science 228:190 (1985); During et al., Ann . Neurol . 5:351 (1989); Howard et al., J. Neurosurg. 2i :1 °5 (1989)). In yet another embodiment, a controlled release system can be placed in proximity of the therapeutic target, i.e., the brain, thus requiring only a fraction of the systemic dose (see , e . g. , Goodson, in Medical Applications of Controlled Release, supra , vol. 2, pp. 115-138 (1984)) . Other controlled release syεtemε are diεcussed in the review by Langer (Science 249:1527-1533 (1990)). In a specific embodiment where the Therapeutic iε a nucleic acid encoding a protein Therapeutic, the nucleic acid can be administered in vivo to promote expresεion of itε encoded protein, by conεtructing it aε part of an appropriate nucleic acid expreεsion vector and administering it so that it becomes intracellular, e.g., by use of a retroviral vector (see U.S. Patent No. 4,980,286), or by direct injection, or by uεe of microparticle bombardment (e.g., a gene gun; Bioliεtic, Dupont) , or coating with lipids or cell-surface receptors or transfecting agentε, or by adminiεtering it in linkage to a homeobox-like peptide which is known to enter the nucleus (see e.g., Joliot et al., Proc . Natl . Acad . Sci . USA £8.1864-1868 (1991)), etc. Alternatively, a nucleic acid Therapeutic can be introduced intracellularly and incorporated within host cell DNA for expression, by homologous recombination. The present invention alεo provides pharmaceutical compositions. Such compositions comprise a therapeutically effective amount of a Therapeutic, and a pharmaceutically acceptable carrier. In a specific embodiment, the term "pharmaceutically acceptable" means approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans. The term "carrier" refers to a diluent, adjuvant, excipient, or vehicle with which the therapeutic is administered. Such pharmaceutical carriers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water is a preferred carrier when the pharmaceutical composition is administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid carriers, particularly for injectable εolutionε. Suitable pharmaceutical excipientε include starch, glucose, lactoεe, sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene, glycol, water, ethanol and the like. The composition, if desired, can also contain minor amountε of wetting or emulεifying agentε, or pH buffering agentε. Theεe compoεitionε can take the form of solutionε, suspensionε, emulεion, tabletε, pills, capsules, powders, sustained-release formulations and the like. The composition can be formulated aε a εuppoεitory, with traditional binderε and carrierε εuch aε triglycerides. Oral formulation can include standard carriers such aε pharmaceutical gradeε of mannitol, lactoεe, εtarch, magneεium εtearate, sodium saccharine, cellulose, magnesium carbonate, etc. Examples of suitable pharmaceutical carriers are described in "Remington'ε Pharmaceutical Sciences" by E.W. Martin. Such compositionε will contain a therapeutically effective amount of the Therapeutic, preferably in purified form, together with a suitable amount of carrier so as to provide the form for proper administration to the patient. The formulation εhould suit the mode of administration. In a preferred embodiment, the compoεition iε formulated in accordance with routine procedures as a pharmaceutical composition adapted for intravenous administration to human beingε. Typically, compositions for intravenous administration are solutionε in sterile isotonic aqueouε buffer. Where neceεεary, the compoεition may alεo include a εolubilizing agent and a local aneεthetic εuch aε lignocaine to eaεe pain at the εite of the injection. Generally, the ingredientε are εupplied either εeparately or mixed together in unit dosage form, for example, as a dry lyophilized powder or water free concentrate in a hermetically sealed container such as an ampoule or sachette indicating the quantity of active agent. Where the compoεition iε to be adminiεtered by infusion, it can be dispensed with an infusion bottle containing sterile pharmaceutical grade water or saline. Where the composition iε adminiεtered by injection, an ampoule of εterile water for injection or saline can be provided so that the ingredientε may be mixed prior to administration. The Therapeuticε of the invention can be formulated aε neutral or salt forms. Pharmaceutically acceptable saltε include thoεe formed with free amino groupε εuch aε thoεe derived from hydrochloric, phoεphoric, acetic, oxalic, tartaric acidε, etc., and thoεe formed with free carboxyl groupε εuch aε those derived from sodium, potassium, ammonium, calcium, ferric hydroxides, iεopropylamine, triethylamine, 2-ethylamino ethanol, hiεtidine, procaine, etc. The amount of the Therapeutic of the invention which will be effective in the treatment of a particular diεorder or condition will depend on the nature of the disorder or condition, and can be determined by standard clinical techniques. In addition, in vitro assays may optionally be employed to help identify optimal dosage ranges. The precise dose to be employed in the formulation will also depend on the route of administration, and the seriousnesε of the disease or disorder, and εhould be decided according to the judgment of the practitioner and each patient'ε circumεtanceε . However, suitable dosage ranges for intravenous administration are generally about 20-500 micrograms of active compound per kilogram body weight. Suitable dosage ranges for intranasal administration are generally about 0.01 pg/kg body weight to 1 mg/kg body weight. Effective doseε may be extrapolated from doεe- reεponεe curves derived from in vitro or animal model test system . Suppositories generally contain active ingredient in the range of 0.5% to 10% by weight; oral formulations preferably contain 10% to 95% active ingredient. The invention also provides a pharmaceutical pack or kit compriεing one or more containers filled with one or more of the ingredients of the pharmaceutical compositions of the invention. Optionally associated with such container (s) can be a notice in the form preεcribed by a governmental agency regulating the manufacture, uεe or εale of pharmaceuticalε or biological products, which notice reflectε approval by the agency of manufacture, uεe or sale for human administration. 5.7. ANIMAL MODELS The invention alεo provideε animal modelε. In one embodiment, animal modelε for εtroke or iεchemic disease, specifically ischemic εtroke (e.g., aε deεcribed in Section 5.8) are provided. In one embodiment, SHRSP animalε are bred with normal or non-εtroking rats not having a mutant ANF allele. Rats can be selected that have the chromosome 1 locuε for εtoke prediεpoεition but do not have the chromoεome 5 locuε (i.e. have a wild type ANF locus) or, optionally the chromosome 4 locuε, demonεtrated to be protective for stroke in the SHRSP strain. Such animalε can be used to test for mutant ANF proteins with reduced activity or for ANF antagonistε aε described in Section 5.7 supra . Additionally, transgenic animals can be generated that overexpreεε or miεexpreεε the ANF gene, e.g. by introducing the ANF gene under the control of a heterologouε promoter or a promoter that cauεeε the expreεsion of ANF in tissueε not normally expressing ANF. Additionally, "knockout" mice can be initially produced by promoting homologous recombination between a ANF gene in its chromoεome and an exogenous ANF gene that has been rendered biologically inactive (preferably by inεertion of a heterologouε sequence, e.g., an antibiotic resistance gene) or by non-homologous recombination. In a preferred aspect, introduction of heterologous DNA is carried out by transforming embryo-derived stem (ES) cells with a vector containing the insertionally inactivated ANF gene or ANF gene under the control of a heterologouε promoter, followed by injecting the ES cellε into a blastocyst, and implanting the blastocyst into a foster mother. The resulting mice are chimeric animals ("knockout animal" or "tranεgenic animal") in which an ANF gene haε been inactivated or overexpreεεed or misexpressed (see Capecchi, Science 244:1288-1292 (1989)). The chimeric animal can be bred to produce additional knockout or transgenic animals. Such animals can be mice, hamsters, sheep, pigε, cattle, etc., and are preferably non-human mammalε. Tranεgenic and knockout animalε can alεo be made in D . me lanog aster , C. elegans , etc. by methodε that are commonly known in the art. One embodiment of the invention provides a recombinant non-human animal containing a mutant ANF gene under the control of a promoter that is not the native ANF gene promoter, in which the mutant ANF gene encodes a mutant ANF that increases latency to stroke. Another embodiment of the invention provides a recombinant non-human animal that iε the product of a proceεε compriεing introducing a nucleic acid into the non-human animal, or an ancestor thereof, said nucleic acid comprising a mutant ANF gene sequence. 6. EXAMPLE Heart tisεue from SHRSP, SHR and WKY ratε waε analyzed by QEA™ to identify and characterize geneε that are differentially expressed in the SHRSP rats as compared to the SHR and WKY rats. 6.1. MATERIALS AND METHODS SHRSP, SHR, and WKY rats were maintained on normal rat chow and water ad libitum . Thirteen week old rats were sacrificed and the hearts removed. The hearts were quick frozen in liquid nitrogen immediately after dissection, and stored at -70°C until processing for QEA™. Total cellular RNA was extracted from 5 mg of heart tisεue by firεt grinding the tissue into a fine powder on liquid nitrogen. The tissue powder was transferred to a tube containing 500 μl Triazol reagent (εee Chomεzynεki et al. 1987, Annal . Biochem . 162 156-159 and Chomεzynεki et al., 1993, Biotechniques 15:532-532,536-537; reagent obtained from Life Technologieε, Gaithersburg, MD) and was dispersed in the Triazol using a Polytron homogenizer from Brinkman Instrumentε (Westbury, NY) . The cellular RNA fraction waε extracted with 50 μl BCP (l-bromo-3-chloropropane) (Molecular Reεearch, Cincinnati, OH) . The extraction mixture was centrifuged for 15 minuteε at 4°C at 12,000X G, and the aqueouε phaεe waε removed to a fresh tube. The RNA was then precipitated with 0.5 volumes isopropanol per original amount of Triazol reagent used, and the sample centrifuged at room temperature for 10 minutes at 12,OO0X G. The supernatant was discarded, the pellet washed with 70% ethanol and then centrifuged at room temperature for 5 minutes at 12,000X G. Finally the 70% ethanol was removed and the centrifuge tube was let stand to dry in an inverted position. The resulting RNA pellet waε reεuεpended in 100 μl water (1 μl per mg of original tiεεue weight) and heated to 55°C until completely diεεolved. The RNA εamples were then treated with DNAse to remove DNA. 28 μl of 5X reverse transcriptase buffer (Life Technologies, Gaithersburg, MD) , 10 μl 0.1 M DTT, and 5 units RNAguard per 100 mg starting tissue (Pharmacia Biotech, Uppsala, Sweden) and 1 unit RNaεe-free DNaεe I (Pharmacia Biotech) per 100 mg starting tisεue were added to the resuspended RNA samples. The reaction mixture was incubated at 37°C for 20 minutes. The total RNA concentration was quantified by measuring OD 260 of a 100 fold dilution and the samples stored at -20°C. Poly-adenylated mRNA was isolated from the total RNA preparations using magnetic bead mediated oligo-dT detection with the Dynabeads mRNA Direct Kit from Dynal (Oslo, Norway) as directed by the manufacturer. The poly-adenylated RNA was harvested in a small volume of water, quantified by OD 260 measurement, and stored at -20°C. cDNA was synthesized from the poly-adenylated RNA as follows: The poly A+ RNA was mixed with 50 ng random hexamers (50 ng/μl) in 10 μl of water. The mixture was heated to 70°C for 10 minutes, quick chilled in ice- water slurry, and kept on ice for 1-2 min. The condensate was collected by centrifugation in a microfuge for 10 seconds. The firεt εtrand εyntheεiε waε carried out by adding a reaction mixture of 4 μl 5x firεt strand buffer (from the BRL kit) , 2 μl 100 mM DTT, 1 μl 10 mM dNTP mix, and 2 μl water to the primer-annealed RNA. The reaction mixtures were incubated at 37°C for 2 mins, 1 μl of Superscript II (BRL) (following manufacturer's recommendations) was added, and the reactions were then incubated at 37°C for 1 hr. To synthesize the second cDNA strand, the εampleε were placed on ice, 30 μl of 5X Second strand buffer, 90 μl of cold water, 3 μl of 10 mM dNTP, 1 μL (10 units) of E. coli DNA ligase (BRL) , 4 μl (40 units) of E. coli DNA polymeraεe (BRL), and 1 μl (3.5 unitε) of E. coli RNaεeH (BRL) were added to the tubeε, and the reactionε were incubated for 2 hourε at 16°C. The reεulting cDNA waε then incubated with 2 μl of T4 DNA polymeraεe (5 unitε) at 16°C for 5 min. The reεulting cDNA waε dephoεphorylated with Arctic Shrimp Alkaline Phosphatase ("SAP"; obtained from USB); 20 μl 10X SAP buffer, 25 μl of water, and 5 μl (5 units) of SAP were added to the reaction mixtures and incubated at 37°C for 30 min. The cDNA was extracted with phenol-chloroform, chloroform-iεoamyl alcohol, precipitated from the aqueouε phase by addition of Na-acetate to 0.3 M, 20 μg glycogen, and 2 vol of ethanol, incubation at -20°C for 10 min., and collected by centrifugation at 14,000 g for 10 min. The supernatant waε removed and the pellet washed with 75% ethanol, resuεpended in TE, and the cDNA quantitated. For subsequent QEA™ processing, 75 ng cDNA was transferred to a separate tube, resuspended in TE to a concentration 600 ng/ml, and stored at -20°C. QEA™ analysis (see PCT Publication WO 97/15690 dated May 1, 1997) was performed with BεrFI and Bglll reεtriction enzymes. Adapter molecules for the QEA™ analysis were prepared from linker and primer oligonucleotides. For the "sticky ends" generated by the BsrFI restriction enzyme, the linker oligonucleotide 5'-GGCCCGAAGTACA-3 ' (SEQ ID NO: 15) and the primer oligonucleotide 5'-GGCCCGAAGTAC-3' (SEQ ID NO: 16) were used. For the Bglll reaction "sticky ends", the linker oligonucleotide 5'-GGCCCAGCCACT-3' (SEQ ID NO: 17) and the primer oligonucleotide 5'-GGCCCAGCCAC-3' (SEQ ID NO: 18) were used. One set of primers were labeled with FAM fluorescent label and one set were labeled with a biotin moiety. The adapters were prepared by mixing the linker and primer oligonucleotideε together in water at a concentration ratio of 1:20 (linker to primer) with the primer at a total concentration of 50 pm per μl. The mixture waε incubated at 50°C for 10 minutes and then allowed to cool slowly to room temperature to anneal the linkers and primers. The adapters were stored at -20°C. The QEA™ reactions were performed using an automated QEA™ procedure. Reactions were preformed in a standard 96 well thermal cycler format using a Beckman Biomek 2000 robot (Beckman, Sunnyvale, CA) . The 3 cDNA εampleε were analyzed in triplicate with BεrFI and Bglll restriction enzymes. All steps were performed by the robot, including solution mixing, from user provided stock reagents, and temperature profile control. The RE/ligase reaction contained the following componentε per reaction: 1. 1 U each BsrFI and Bglll (New England Biolabε, Beverly, MA) 2. 1 μl of each annealed adapter prepared aε above (10 pm) 3. 0.1 μl T4 DNA ligase [1 U/μl] (Life Technologies (Gaithersburg, MD) 4. 1 μl ATP (Life Technologies, Gaithersburg, MD) 5. 5 ng of the prepared cDNA 6. 1.5 μl 10X NEB 2 buffer from New England Biolabs (Beverly, MA) 7. 0.5 μl of 50 mM MgCl 2 8. Water to bring total volume to 10 μl and transfer to thermal cycler. The robot performed the RE/ligation reaction in a PTC- 100 Thermal Cycler equipped with a mechanized lid from MJ Research (Watertown, MA) with the following temperature profile: 15 minutes at 37°C, ramp down 21°C in 5 minutes, 16°C for 30 minutes, 37°C-for 10 minutes, and 65°C for 10 minutes. The PCR reaction mix contained the following components per reaction: 1. 10 μl 5X E-Mg (300 mM Triε-HCl pH 9.0, 75 mM (NH 4 ) 2 S0 4 ) 2. 100 pm of BsrFI and Bglll primers (SEQ ID NOS: 16 and 18, respectively) (one εet labeled with FAM; the other εet labeled with biotin) . 3. 1 μl 10 mM dNTP mix (Life Technologieε, Gaitherεburg, MD) 4. 2.5 U of 50:1 Taq polymeraεe (Life Technologieε, Gaithersburg, MD) : Pfu polymerase (Stratagene, " La Jolla, CA) 5. Water to being volume to 35 μl per PCR reaction The PCR mix was heated to 72°C and 35 μl was tranεferred to each digeεtion/ligation reaction. The PTC-100 Thermal Cycler then performed the PCR reaction with a thermal profile of 72°C for 10 minuteε, 15 cycleε of 95°C for 30 εecondε and 68°C for 1 minute, and then 72°C for 10 minuteε, and finally holding the reactionε at 4°C. Before further analysis, the QEA products were subjected to a post-PCR clean up protocol aε follows: 1. Streptavidin magnetic beadε (Catalog No. MSTR0510 of CPG, Lincoln Park, N.J.) were prepared (3 μl of beadε for every 5 μl of QEA™ reaction product) by pre-waεhing beadε in 10 μl binding buffer (5 M NaCl, 10 mM Triε, pH 8.0, 1 mM EDTA) per 5 μl original volume of QEA™ reaction product. 2. 10 μl of washed beads were dispensed in a 96 well FALCON™ TC plate for every QEA™ sample procesεed. 3. QEA™ productε were added to the beads, mixed well and incubated for 30 minutes at 50°C. 4. The εample volume was made 100 μl with binding buffer, the plate placed on a 96 well magnetic particle concentrator, and the beads allowed to migrate for 5 minutes. 5. The liquid waε then removed, and 200 μl waεhing buffer (10 mM Tris, pH 7.4, 10 mM EDTA) added per well. 6. Washing step 5 waε repeated. For analyεiε, the beads were resuεpended in 5 μl loading buffer (80% deionized formamide, 20% 25 mM EDTA, pH 8.0, 50 mg/ml Blue dextran) per 5 μl of beadε, and the εupernatant WAs then analyzed by electrophoresis on an ABI 377 (Applied Biosyεtemε, Inc.) automated εequencer under denaturing conditionε uεing the Gene Scan εoftware (ABI) for analyεis. The GeneScan 500 ROX ladder was diluted 1:10 in loading buffer and analyzed as a size control. "Oligonucleotide poisoning" was performed to confirm that the differentially expressed fragment was derived from ANF. Esεentially, an unlabeled oligonucleotide having a nucleotide εequence able to hybridize to the ANF εequence (and prevent amplification with the labeled primerε) waε included in a PCR reaction using the QEA™ reaction products as substrate. The specific "poisoning" primer has the sequence 5'-AAGATGCCGGTAGAAG-3' (SEQ ID NO: 19). Specifically, for the oligonucleotide poisoning, each reaction mixture contained 1 μl of a 1:100 dilution of the QEA™ reaction products, 5 μl TB 2.0 (500 mM Tris-HCl pH 9.15, 160 mM (NH 4 ) 2 S0 4 , 20 mM MgCl 2 ) , 2 μl 10 mM equimolar mixture of all four dNTPε, 0.2 μl each BεrFI and Bglll primerε (100 pm/ l) , 2 μl ANF poisoning primer (1000 pm/ml) , 1 μl 5 M betaine, l μl NEB 2 buffer (10 mM Tris-HCl, 10 mM MgCl 2 , 50 mM NaCl, 1 mM DTT (pH 7.9 at 25°C) , 0.25 μl 25 U/ml of a 16:1 mixture of Klentaq:pfu, and 38 μl water. The following PCR temperature protocol waε performed in a thermal cycler for 13 cycles: 96° C for 30 εecondε; 57° C for 1 minute; 72° C for 2 minuteε. The amplified products were held at 4° C. and then analyzed aε described above on the automatic sequencer. 6.2. RESULTS 5 Quantitative Expresεion Analysis (QEA ™ ) was used to compare the gene expression profiles of heartε from WKY, SHR and SHRSP ratε fed a normal diet. The QEA ™ method enableε compariεon of the level of expreεεion of all transcribed sequences among the sampleε with a εensitivity of l part in 10 125,000. A total of 12,000 gene fragments, generated from approximately 6000 geneε, were compared between heartε εampleε of each rat εtrain in triplicate. The comparison between the WKY and SHR rat yielded 68 different fragments (0.6%), the SHR and SHRSP comparison yielded 29 differences 15 (0.02%), and the WKY and SHRSP comparison yielded 97 differenceε (0.8%). Through the QEA™ analyεis, the inventors diεcovered that ANF waε expressed at different levels among theεe rat strains. The peak representing ANF mRNA was 2-fold more 20 intense in SHRSP and WKY hearts relative to the SHR heart (Figures 1A and B) . Oligonucleotide poisoning confirmed that the entire magnitude of the intensity peak asεociated with the ANF tranεcript was due to amplification of the ANF gene (Figures 1C and D) . 25 Comparison of the ANF sequenceε from SHRSP and SHR rats revealed 9 nucleotide differences, indicating that the SHRSP ANF allele was most likely derived from a foreign rat inadvertently introduced into the colony. One nucleotide substitution changed the glycine at position 99 of proANP as 30 depicted in Figure 3 (SEQ ID NO: 2) to a serine residue (Figureε IE and F) (a G to A change at nucleotide number 1125 aε depicted in Figure 4 (SEQ ID No: 3)) and most likely accounts for the protective effect of the allele. Thiε glycine reεidue iε conεerved among rat, pig, horεe and human 35 and may affect proANP processing and/or the binding of ANF to its receptor. Four variants in the third (i . e . the variant or wobble positions of the codon) positionε of the nucleotide sequences coding for the valine at amino acid 27 (an A to G change at nucleotide number 805 as depicted in Figure 4 (SEQ ID NO:3)), the proline at amino acid 59 (a G to A change at nucleotide number 1007 as depicted in Figure 4 (SEQ ID NO:3)), the alanine at position 71 (a G to A change at nucleotide number 1043 as depicted in Figure 4 (SEQ ID NO:3)), and the glutamate at position 85 (an A to G change at nucleotide number 1085 as depicted in Figure 4 (SEQ ID NO: 3)) and 4 variants in the 3' untranεlated region (a C to T change and a T to C change at nucleotide numberε 1866 and 1868, reεpectively, aε depicted in Figure 4 (SEQ ID NO: 3) and a two baεepair deletion) , of SHRSP-Anf do not affect the predicted protein εequence. The diεcovery of both a 2-fold increase in mRNA, as well as a protein-altering mutation in ANF in a protective role for stroke onset suggestε the mutant protein as a potential therapeutic for stroke. The present invention iε not to be limited in scope by the specific embodiments described herein. Indeed, various modifications of the invention in addition to those described herein will become apparent to those skilled in the art from the foregoing description and accompanying figures. Such modifications are intended to fall within the scope of the appended claims. Various publication are cited herein, the disclosures of which are incorporated by reference in their entireties.

Claims: WHAT IS CLAIMED IS; 1. A purified mutant ANF having one or more subεtitutions of amino acid residueε and that binds to an anti-ANF antibody. 2. The purified mutant ANF of claim 1 in which said one or more subεtitutionε are in amino acid residues selected from among amino-terminal residues at positions 1-10 of human ANF as depicted in Figure 5 (SEQ ID NO:4). 3. The purified mutant ANF of claim 2 in which said one or more subεtitutionε are in amino acid reεidueε εelected from among amino-terminal reεidueε at positions 1-5 of human ANF as depicted in Figure 5 (SEQ ID NO: 4). 4. The purified mutant ANF of claim 3 in which εaid one or more substitutions are in amino acid residues selected from among amino-terminal residues at positions 1-2 of human ANF as depicted in Figure 5 (SEQ ID NO: 4). 5. The purified mutant ANF of claim 4 in which εaid substitutions are a single substitution at the position correεponding to position 1 of the amino acid sequence of rat ANF aε depicted in Figure 5 (SEQ ID NO: 4) . 6. The purified mutant ANF of claim 5 in which εaid substitution at said position 1 is an amino acid selected from the group conεiεting of serine, threonine, and tyrosine. 7. The purified mutant ANF of claim 6 in which said amino acid is a εerine. 8. The purified mutant ANF of claim 1 which is a human mutant ANF in which said substitutions are its only mutation. 9. A purified mutant ANF that increases latency to stroke in stroke prone rats fed a high salt diet. 10. An isolated nucleic acid compriεing a nucleotide sequence encoding the mutant ANF of claim 1. 11. An isolated nucleic acid comprising a nucleotide εequence encoding the mutant ANF of claim 2. 12. An iεolated nucleic acid comprising a nucleotide sequence encoding the mutant ANF of claim 3. 13. An iεolated nucleic acid compriεing a nucleotide εequence encoding the mutant ANF of claim 4. 14. An isolated nucleic acid comprising a nucleotide sequence encoding the mutant ANF of claim 5. 15. An isolated nucleic acid comprising a nucleotide sequence encoding the mutant ANF of claim 6. 16. An isolated nucleic acid comprising a nucleotide sequence encoding the mutant ANF of claim 7. 17. An isolated nucleic acid comprising a nucleotide sequence encoding the mutant ANF of claim 8. 18. An isolated nucleic acid comprising a nucleotide sequence encoding the mutant ANF of claim 9. 19. A method of treating or preventing or delaying stroke comprising administering to a subject in which such treatment or prevention or delay is deεired an amount of a mutant ANF εufficient to treat or prevent or delay εtroke. 20. The method of claim 19 in which said mutant ANF has one or more substitutions of amino acid residues and binds to an anti-ANF antibody. 21. The method of claim 20 in which said one or more substitutionε are in amino acid residues selected from among amino-terminal residues at positionε 1-10 of human ANF aε depicted in Figure 5 (SEQ ID NO: 4) . 22. The method of claim 21 in which said one or more subεtitutions are in amino acid residues selected from among amino-terminal residueε at poεitions 1-5 of human ANF as depicted in Figure 5 (SEQ ID NO: 4) . 23. The method of claim 22 in which said one or more substitutionε are in amino acid reεidues selected from among amino-terminal residues at positions 1-2 of human ANF as depicted in Figure 5 (SEQ ID NO:4). 24. The method of claim 20 in which said substitutions are a single substitution at the position corresponding to position 1 of the amino acid sequence of human ANF as depicted in Figure 5 (SEQ ID NO: 4). 25. The method of claim 24 in which in which εaid substitution at said position 1 is an amino acid selected from the group consisting of serine, threonine, and tyrosine. 26. The method of claim 25 in which said amino acid is a εerine. 27. The method of claim 19 in which said subject is a human and in which said subεtitutionε are the only mutationε in ANF. 28. The method of claim 19 in which said mutant ANF iε administered to prevent stroke in a subject having one or more risk factors for stroke. 29. The method of claim 19 in which said stroke is iεchemic stroke. 30. The method of claim 19 in which said mutant ANF increases latency to stroke in stroke prone rats fed a high εalt diet. 31. The method of claim 19 in which said mutant ANF has a longer half life in vivo relative to wild type ANF. 32. A pharmaceutical composition compriεing a therapeutically or prophylactically effective amount of a mutant ANF having one or more substitutions of amino acid residues and that binds to an anti-ANF antibody; and a pharmaceutically acceptable carrier. 33. The pharmaceutical composition of claim 32 in which said one or more substitutions are in amino acid residues selected from among amino-terminal residues at positions 1-10 of human ANF as depicted in Figure 5 (SEQ ID NO:4). 34. The pharmaceutical compoεition of claim 33 in which said one or more substitutions are in amino acid residues selected from among amino-terminal residues at positionε 1-5 of human ANF as depicted in Figure 5 (SEQ ID NO: 4). 35. The pharmaceutical composition of claim 34 in which said one or more substitutions are in amino acid residueε selected from among amino-terminal residues at positions 1-2 of human ANF as depicted in Figure 5 (SEQ ID NO: 4) . 36. The pharmaceutical composition of claim 32 in which said substitutionε are a single substitution at the position corresponding to position 1 of the amino acid sequence of human ANF as depicted in Figure 5 (SEQ ID NO: 4) . 37. The pharmaceutical composition of claim 36 in which said substitution at said position 1 is an amino acid selected from the group consisting of serine, threonine, and tyrosine. 38. The pharmaceutical composition of claim 37 in which εaid amino acid iε a serine. 39. The pharmaceutical composition of claim 32 in which said mutant ANF is a human mutant ANF in which εaid εubstitutions are its only mutations. 40. The pharmaceutical composition of claim 32 in which said mutant ANF has a longer half life in vivo relative to wild type ANF. 41. A pharmaceutical composition comprising a therapeutically or prophylactically effective amount of a mutant ANF that increases latency to stroke in stroke prone rats fed a high salt diet; and a pharmaceutically acceptable carrier. 42. A pharmaceutical composition comprising a therapeutically or prophylactically effective amount of a nucleic acid containing a nucleotide sequence encoding a mutant ANF having one or more substitutions of amino acid residueε and that bindε to an anti-ANF antibody; and a pharmaceutically acceptable carrier. 43. The pharmaceutical composition of claim 42 in which said one or more substitutions are in amino acid residues selected from among amino-terminal residues at positions 1-10 of human ANF as depicted in Figure 5 (SEQ ID NO: 4) . 44. The pharmaceutical composition of claim 43 in which said one or more substitutionε are in amino acid residues selected from among amino-terminal residueε at poεitionε 1-5 of human ANF aε depicted in Figure 5 (SEQ ID NO: 4). 45. The pharmaceutical composition of claim 44 in which said one or more substitutions are in amino acid residues selected from among amino-terminal residues at positions 1-2 of human ANF as depicted in Figure 5 (SEQ ID NO: 4) . 46. The pharmaceutical composition of claim 42 in which said substitutions are a single substitution at the position corresponding to position 1 of the amino acid sequence of human ANF as depicted in Figure 5 (SEQ ID NO: 4). 47. The pharmaceutical composition of claim 46 in which said εubstitution at said position 1 iε an amino acid selected from the group consisting of serine, threonine, and tyrosine. 48. The pharmaceutical composition of claim 47 in which said amino acid is a serine. 49. The pharmaceutical composition of claim 42 in which said mutant ANF has a longer half life in vivo relative to wild type ANF. 50. The pharmaceutical composition of claim 42 in which said nucleic acid is a nucleic acid vector. 51. A pharmaceutical composition comprising a therapeutically or prophylactically effective amount of a nucleic acid containing a nucleotide sequence encoding a mutant ANF that increaεes latency to stroke in stroke prone rats fed a high salt diet; and a pharmaceutically acceptable carrier. 52. The pharmaceutical compoεition of claim 51 in which said nucleic acid is a nucleic acid vector. 53. A method for screening for an allele protective against stroke in a subject comprising detecting a mutant ANF allele, the preεence of εaid mutant ANF allele being indicative of an allele protective for εtroke. 54. The method of claim 53 in which said mutant ANF allele encodes a mutant ANF having an amino acid substitution corresponding to position 1 of the amino acid sequence of human ANF as depicted in Figure 5 (SEQ ID NO: 4). 55. An oligonucleotide comprising the nucleotide sequence AGAGATGGAGGTGCCCTCGGGCGGA (SEQ ID NO: 15). 56. A kit comprising in one or more containers a therapeutically or prophylactically effective amount of a mutant ANF protein. 57. A method for screening for a modulator of ANF activity or of latency or predisposition to stroke comprising: (a) administering a putative modulator of ANF activity to an animal prone to stroke; and (b) measuring one or more physiological parameterε associated with ANF activity, in which a change in said one or more parameters relative to an animal not administered the putative modulator indicateε that the putative modulator modulates ANF activity or latency or predisposition to stroke. 58. The method of claim 57 in which the animal prone to stroke is fed a high salt diet. 59. The method of claim 57 in which the one or more physiological parameters is stroke latency. 60. The method of claim 57 in which the test animal is a recombinant test animal which expresεeε an ANF tranεgene or expresses ANF under the control of a promoter that is not the native ANF gene promoter at an increaεed level relative to a wild type teεt animal. 61. A method for screening an ANF mutant for its ANF activity comprising: (a) administering the ANF mutant to a test animal prone to stroke; and (b) measuring stroke latency in the test animal, in which stroke latency is indicative of ANF activity. 62. The method of claim 61 in which the test animal is a recombinant teεt animal which expreεεeε an ANF tranεgene or expreεses ANF under the control of a promoter that is not the native ANF gene promoter at an increased level relative to a wild type test animal. 63. A method for screening for a modulator of ANF activity or of latency or predisposition to stroke comprising measuring stroke latency in a stroke prone animal that recombinantly expresses a putative modulator of ANF activity, in which a change in stroke latency relative to an analogous stroke prone animal that does not recombinantly express the putative modulator indicates that the putative modulator modulates ANF activity or latency or predisposition to stroke. 64. A method for screening an ANF mutant for an effect on latency or predisposition to stroke comprising measuring stroke latency in a stroke prone animal that recombinantly expresses an ANF mutant, in which a change in stroke latency relative to an analogous stroke prone animal that does not recombinantly express the ANF mutant indicates that the ANF mutant has an effect on latency or predisposition to stroke. 65. The method of claim 64 in which said ANF mutant is screened for an increase in stroke latency or a decrease in predisposition to stroke. 66. A recombinant non-human animal containing a mutant ANF gene under the control of a promoter that is not the native ANF gene promoter, in which the mutant ANF gene encodes a mutant ANF that increaseε latency to stroke. 67. A recombinant non-human animal that is the product of a proceεs comprising introducing a nucleic acid into the non-human animal, or an ancestor thereof, said nucleic acid comprising a mutant ANF gene sequence. 68. A purified human mutant ANF in which its only mutation iε a substitution of serine for glycine at position 1 of its amino acid sequence. 69. An isolated nucleic acid comprising a nucleotide sequence encoding the mutant ANF of claim 68. 70. A method of treating or preventing or delaying stroke comprising administering to a subject in which such treatment or prevention or delay is desired an amount of the mutant ANF of claim 68 sufficient to treat or prevent or delay stroke. 71. A pharmaceutical composition compriεing a therapeutically or prophylactically effective amount of the mutant ANF of claim 68; and a pharmaceutically acceptable carrier. 72. A purified mutant proANP having one or more substitutionε of amino acid reεidues in the ANF sequence, and that binds to an anti-proANP antibody or anti-ANF antibody.

Inventors: SHIMKETS RICHARD A, SHIMKETS, RICHARD, A.
Applicants: CURAGEN CORP, SHIMKETS RICHARD A, CURAGEN CORPORATION, SHIMKETS, RICHARD, A.
Application year: 1998
Main classification: A01K67
IPC codes: A01K67, A61K38, A61K48, A61P9, C07K14, C12N15, C12P21, G01N33