bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Function and Membrane Binding Properties Are Correlated for
Escherichia coli
lamB Signal Peptides
Authors: Briggs Martha S. , Gierasch Lila M. , Zlotnick Adam , Lear James D. , DeGrado William F.
Published: October 2006

Wild-type and pseudorevertant signal peptides of the
lamB
gene product of
Escherichia coli
interact with lipid systems whereas a nonfunctional deletion mutant signal peptide does not. This conclusion is based on (i) interaction of synthetic signal peptides with a lipid monolayer-water surface, (ii) conformational changes induced by presence of lipid vesicles in an aqueous solution of signal peptide, and (iii) capacities of the peptides to promote vesicle aggregation. Analysis of the signal sequences and previous conformational studies suggest that these lipid interaction properties may be attributable to the tendency of the functional signal peptides to adopt α-helical conformations. Although the possibility of direct interaction between the signal peptide and membrane lipids during protein secretion is controversial, the results suggest that conformationally related amphiphilicity and consequent membrane affinity of signal sequences are important for function in vivo.
Identification of Germline and Somatic Mutations Affecting the Retinoblastoma Gene
Authors: Dunn James M. , Phillips Robert A. , Becker Andrew J. , Gallie Brenda L.
Published: October 2006

Retinoblastoma (RB) is a malignant tumor of developing retina that arises when abnormalities resulting in loss of function affect both alleles of the gene at the retinoblastoma locus (RB1) on chromosome 13q. The majority of RB tumors do not show gross alterations in a 4.7-kb fragment (4.7R), which is a candidate RB1 gene. To search for more subtle mutations, the ribonuclease protection method was used to analyze 4.7R messenger RNA from RB tumors. Five of 11 RB tumors, which exhibit normal 4.7R DNA and normal-sized RNA transcripts, showed abnormal ribonuclease cleavage patterns. Three of the five mutations affected the same region of the messenger RNA, consistent with an effect on splicing involving an as yet unidentified 5′ exon. The high frequency of mutations in 4.7R supports the identification of 4.7R as the RB1 gene. However, the unusual nature of some of the abnormalities of 4.7R alleles indicates that the accepted sequence of genetic events involved in the genesis of RB may require reevaluation.
Development of Disease and Virus Recovery in Transgenic Mice Containing HIV Proviral DNA
Authors: Leonard John M. , Abramczuk Jan W. , Pezen David S. , Rutledge Rosamond , Belcher J. Harry , Hakim Frances , Shearer Gene , Lamperth Lajos , Travis William , Fredrickson Torgny , Notkins Abner L. , Martin Malcolm A.
Published: October 2006

Transgenic mice containing intact copies of the human immunodeficiency virus (HIV) proviral DNA were constructed. Founder animals were not viremic for HIV and remained healthy during a 9-month observation period. After being mated with nontransgenic animals, one founder mouse (No. 13) gave rise to F
1
progeny that developed a disease syndrome characterized by marked epidermal hyperplasia, lymphadenopathy, splenomegaly, pulmonary lymphoid infiltrates, growth retardation, and death by day 25 of life. Infectious HIV, indistinguishable from parental virus by immunoblot analysis, was recovered from the spleen, lymph nodes, and skin of five of five affected animals.
Infection of the SCID-hu Mouse by HIV-1
Authors: Namikawa R. , Kaneshima H. , Lieberman M. , Weissman I. L. , McCune J. M.
Published: October 2006

SCID-hu mice with human fetal thymic or lymph node implants were inoculated with the cloned human immunodeficiency virus-1 isolate, HIV-1
JR-CSF
. In a time- and dose-dependent fashion, viral replication spread within the human lymphoid organs. Combination immunohistochemistry and in situ hybridization revealed only viral RNA transcripts in most infected cells, but some cells had both detectable viral transcripts and viral protein. Infected cells were always more apparent in the medulla than in the cortex of the thymus. These studies demonstrate that an acute infection of human lymphoid organs with HIV-1 can be followed in the SCID-hu mouse.
Control of Influenza and Poliomyelitis with Killed Virus Vaccines
Authors: Salk Jonas , Salk Darrell
Published: October 2006

The requirements for inducing immunity against an infectious disease are outlined, and the application of these requirements to the development of effective vaccines (vaccinology) is discussed. Influenza and poliomyelitis are examined from this viewpoint, and data are presented that demonstrate the effectiveness of killed virus vaccines against these diseases. A comparison between live and killed poliovirus vaccines suggests the desirability of returning to the use of a killed virus vaccine for the eradication of polio. The natural history of influenza and experience with vaccination suggest that influenza might be brought under effective control by routine immunization in childhood with a polyvalent killed virus vaccine potentiated by an immunologic adjuvant.
Mutagenic Activity of Quercetin and Related Compounds
Authors: Bjeldanes L. F. , Chang G. W.
Published: October 2006

The mutagenic activities of several flavonoids and flavonoid metabolites were examined by means of
Salmonella typhimurium
mutants that reveal base-pair substitution and frameshift mutagens. Of the compounds tested (naringin, rutin, neohesperetin, hesperetin, dihydroquercetin, quercetin, quercetin pentaacetate, permethylquercetin,
m
-hydroxyphenylacetic acid, and
m
,
p
-dihydroxyphenylacetic acid), only quercetin was mutagenic without microsomal activation. With activation, however, the mutagenic activity of quercetin was increased significantly and that of quercetin pentaacetate was revealed. The health implications of these findings and aspects of flavonoid structural requirements for mutagenic activity are discussed.
The Human Immunodeficiency Virus: Infectivity and Mechanisms of Pathogenesis
Authors: Fauci Anthony S.
Published: October 2006

Infection with the human immunodeficiency virus (HIV) results in a profound immunosuppression due predominantly to a selective depletion of helper/inducer T lymphocytes that express the receptor for the virus (the CD4 molecule). HIV also has tropism for the brain leading to neuropsychiatric abnormalities. Besides inducing cell death, HIV can interfere with T4 cell function by various mechanisms. The monocyte serves as a reservoir for HIV and is relatively refractory to its cytopathic effects. HIV can exist in a latent or chronic form which can be converted to a productive infection by a variety of inductive signals.
The
ras
Oncogenes Increase the Intrinsic Resistance of NIH 3T3 Cells to Ionizing Radiation
Authors: Sklar Marshall D.
Published: October 2006

Identification of genes that function to protect cells from radiation damage is an essential step in understanding the molecular mechanisms by which mammalian cells cope with ionizing radiation. The intrinsic radiation resistance (D
0
) of NIH 3T3 cells was markedly and significantly increased by transformation with
ras
oncogenes activated by missense mutations. This radiobiologic activity appeared to be a specific consequence of the
ras
mutations rather than of transformation, since revertant cells that contained functional
ras
genes (but were no longer phenotypically transformed) retained their increased D
0
's.
Action at a Distance Along a DNA
Authors: Wang James C. , Giaever Guri N.
Published: October 2006

A number of ways are known by which an event at one location on a DNA molecule can affect an event at a distant location on the same molecule. Three classes of mechanisms are described for such distal actions: tracking or translocation of a protein along a DNA, the association of two proteins bound at separate sites to form a DNA loop in between, and distal interactions that are affected by the topology of the DNA. The basic characteristics of each type of mechanism are discussed in terms of the known physicochemical properties of DNA. The various modes of action at a distance are often interrelated. Examples include the formation of positively and negatively supercoiled DNA loops by tracking and the strong effects of DNA topology on looping.
Escherichia coli
Secretion of an Active Chimeric Antibody Fragment
Authors: Better Marc , Chang C. Paul , Robinson Randy R. , Horwitz Arnold H.
Published: October 2006

A chimeric mouse-human Fab protein that binds specifically to the human carcinoma cell line C3347 has been expressed and secreted from
Escherichia coli
. This molecule, which contains functionally assembled kappa and Fd proteins, binds as effectively to sites on the surface of C3347 cells as Fab fragments prepared proteolytically from whole chimeric or mouse antibody. The production in
Escherichia coli
of foreign heterodimeric protein reagents, such as Fab, should prove useful in the management of human disease.
Tinkering with Enzymes: What Are We Learning?
Authors: Knowles Jeremy R.
Published: October 2006

It is now possible, by site-directed mutagenesis of the gene, to change any amino acid residue in a protein to any other. In enzymology, application of this technique is leading to exciting new insights both into the mechanism of catalysis by particular enzymes, and into the basis of catalysis itself. The precise and often delicate changes that are being made in and near the active sites of enzymes are illuminating the interdependent roles of catalytic groups, and are allowing the first steps to be taken toward the rational alteration of enzyme specificity and reactivity.
A Physical Map of the
Escherichia coli
K12 Genome
Authors: Smith Cassandra L. , Econome Jason G. , Schutt Andrew , Klco Stephanie , Cantor Charles R.
Published: October 2006

A physical map of a genome is the structure of its DNA. Construction of such a map is a first step in the complete characterization of that DNA. The restriction endonuclease Not I cuts the genome of
Escherichia coli
K12 into 22 DNA fragments ranging from 20 kilobases (20,000 base pairs) to 1000 kilobases. These can be separated by pulsed field gel electrophoresis. The order of the fragments in the genome was determined from available
E. coli
genetic information and analysis of partial digest patterns. The resulting ordered set of fragments is a macrorestriction map. This map facilitates genetic and molecular studies on
E. coli
, and its construction serves as a model for further endeavors on larger genomes.
Characterization by Tandem Mass Spectrometry of Structural Modifications in Proteins
Authors: Biemann Klaus , Scoble Hubert A.
Published: October 2006

Tandem mass spectrometry can be used to solve a number of protein structural problems that are not amenable to conventional methods for amino acid sequencing. Typical problems that use this approach involve characterization of peptides with blocked amino termini or peptides that have been otherwise posttranslationally processed, such as, by phosphorylation or sulfation. The structure and homogeneity of synthetic peptides can also be evaluated. Since peptides can be selectively characterized in the presence of other peptides or contaminants, the need for extensive purification is reduced or eliminated.
Immunity to Schistosomes: Progress Toward Vaccine
Authors: Capron André , Dessaint J. P. , Capron M. , Ouma J. H. , Butterworth A. E.
Published: October 2006

Among the major parasitic infections, schistosomiasis may be the most promising candidate for human vaccination. Information about mechanisms of immunity, gained mainly from experimental models but likely to be relevant to human infection, indicates a dynamic balance between protective and regulatory (blocking) mechanisms. Besides cell-mediated responses leading to macrophage activation, antibody-dependent cell-mediated cytotoxicity systems involving precise antibody isotypes and nonlymphoid cells (mononuclear phagocytes, eosinophils, and platelets) appear to be essential effectors of immune attack. The slow development of immunity in humans seems related to the production of antibodies that cross-react with schistosomulum surface antigen and block the binding of antibodies of the effector isotype. Schistosomes that survive in the bloodstream and produce chronic infections may evade the immune system as a result of intrinsic changes in membrane susceptibility and of transient expression of target antigens; at other stages of the parasite life cycle, cross-reactive molecules may be secreted that play an essential role in the induction of immunity. Several schistosome proteins have been characterized as candidates for vaccination. Among these, an antigen of 28 kilodaltons has been cloned and shown to be immunogenic in humans and protective in mice, rats, and baboons.
Education to Prevent AIDS: Prospects and Obstacles
Authors: Fineberg Harvey V.
Published: October 2006

A number of obstacles thwart effective education to prevent AIDS in the United States. These include the biological basis and social complexity of the behaviors that must be changed, disagreement about the propriety of educational messages to prevent AIDS, uncertainty about the degree of risk to the majority of Americans, and dual messages of reassurance and alarm from responsible officials. Long-term protection of an individual from infection requires extreme changes in risk-taking behavior. Partial shifts toward safer practices may be epidemiologically important in retarding the rate and extent of spread of infection. Though some striking changes in behavior have occurred, especially in homosexual populations in areas with high prevalence of AIDS, educational efforts to date have succeeded more in raising awareness and knowledge about AIDS than in producing sufficient changes in behavior. The United States has yet to mount a nationwide comprehensive, intensive, and targeted education program to prevent AIDS.
Cell-Cell Interactions in the Guidance of Late-Developing Neurons in
Caenorhabditis elegans
Authors: Walthall W. W. , Chalfie Martin
Published: October 2006

The initial outgrowth of developing neuronal processes can be affected by a number of extrinsic interactions. Cell-cell interactions are also important in a later stage of neuronal outgrowth when processes grow into the region of their targets. The correct positioning of the process of a postembryonic sensory neuron, the touch cell AVM of the nematode
Caenorhabditis elegans
, at its synaptic targets requires the presence of a pair of embryonic interneurons, the BDU cells. These cells receive synapses from AVM but do not participate in the touch reflex circuit. Therefore, the AVM-BDU synapses may be required to stabilize the association between these cells and assist in the guidance of the AVM processes through a mature neuropil.
Overexpression of Low Density Lipoprotein (LDL) Receptor Eliminates LDL from Plasma in Transgenic Mice
Authors: Hofmann Sandra L. , Russell David W. , Brown Michael S. , Goldstein Joseph L. , Hammer Robert E.
Published: October 2006

A complementary DNA encoding the human low density lipoprotein (LDL) receptor under control of the mouse metallothionein-I promoter was injected into fertilized mouse eggs, and a strain of mice expressing high levels of LDL receptors was established. After administration of cadmium, these mice cleared intravenously injected
125
I-labeled LDL from blood eight to ten times more rapidly than did normal mice. The plasma concentrations of apoproteins B-100 and E, the two ligands for the LDL receptor, declined by more than 90 percent after cadmium treatment, but the concentration of another apoprotein, A-I, was unaffected. Therefore, overexpression of an endocytotic receptor can dramatically lower the ambient concentration of its ligand in vivo.
Generation of cDNA Probes Directed by Amino Acid Sequence: Cloning of Urate Oxidase
Authors: Lee Cheng Chi , Wu Xiangwei , Gibbs Richard A. , Cook Richard G. , Muzny Donna M. , Caskey C. Thomas
Published: October 2006

Urate oxidase (E.C. 1.7.3.3) catalyzes the oxidation of uric acid to allantoin in most mammals except humans and certain primates. The amino-terminal amino acid sequence for porcine urate oxidase was determined and used in a novel procedure for generating complementary DNA (cDNA) probes to this amino acid sequence. The procedure is based on the polymerase chain reaction and utilizes mixed oligonucleotide primers complementary to the reverse translation products of an amino acid sequence. This rapid and simple cDNA cloning procedure is generally applicable and requires only a partial amino acid sequence. A cDNA probe developed by this procedure was used to isolate a full-length porcine urate oxidase cDNA and to demonstrate the presence of homologous genomic sequences in humans.
Probing Structure-Function Relations in Heme-Containing Oxygenases and Peroxidases
Authors: Dawson John H.
Published: October 2006

Structural factors that influence functional properties are examined in the case of four heme enzymes: cytochrome P-450, chloroperoxidase, horseradish peroxidase, and secondary amine mono-oxygenase. The identity of the axial ligand, the nature of the heme environment, and the steric accessibility of the heme iron and heme edge combine to play major roles in determining the reactivity of each enzyme. The importance of synthetic porphyrin models in understanding the properties of the protein-free metal center is emphasized. The conclusions described herein have been derived from studies at the interface between biological and inorganic chemistry.
Phase Determination by Multiple-Wavelength X-Ray Diffraction: Crystal Structure of a Basic "Blue" Copper Protein from Cucumbers
Authors: Guss J. Mitchell , Merritt Ethan A. , Phizackerley R. Paul , Hedman Britt , Murata Mitsuo , Hodgson Keith O. , Freeman Hans C.
Published: October 2006

A novel x-ray diffraction technique, multiple-wavelength anomalous dispersion (MAD) phasing, has been applied to the de novo determination of an unknown protein structure, that of the "blue" copper protein isolated from cucumber seedlings. This method makes use of crystallographic phases determined from measurements made at several wavelengths and has recently been made technically feasible through the use of intense, polychromatic synchrotron radiation together with accurate data collection from multiwire electronic area detectors. In contrast with all of the conventional methods of solving protein structures, which require either multiple isomorphous derivatives or coordinates of a similar structure for molecular replacement, this technique allows direct solution of the classical "phase problem" in x-ray crystallography. MAD phase assignment should be particularly useful for determining structures of small to medium-sized metalloproteins for which isomorphous derivatives are difficult or impossible to make. The structure of this particular protein provides new insights into the spectroscopic and redox properties of blue copper proteins, an important class of metalloproteins widely distributed in nature.
Right-Left Asymmetries in the Brain
Authors: Galaburda Albert M. , LeMay Marjorie , Kemper Thomas L. , Geschwind Norman
Published: October 2006

Structural asymmetries between the hemispheres are found in the human brain. Asymmetries in the auditory regions and in the Sylvian fissures are present even in the fetus. The Sylvian asymmetries may have existed in Neanderthal man and are found consistently in some apes. They may relate to right-left differences in function. Thus, the striking auditory asymmetries could underlie language lateralization. The asymmetries in the frontal and occipital lobes and the lateral ventricles are correlated with hand preference. Anatomical asymmetries may help to explain the range of human talents, recovery from acquired disorders of language function, certain childhood learning disabilities, some dementing illnesses of middle life, and the evidence for behavioral lateralization in nonhuman primates.
Binding of a Cytosolic Protein to the Iron-Responsive Element of Human Ferritin Messenger RNA
Authors: Rouault Tracey A. , Hentze Matthias W. , Caughman S. Wright , Harford Joe B. , Klausner Richard D.
Published: October 2006

The human ferritin H chain messenger RNA contains a specific iron-responsive element (IRE) in its 5′ untranslated region, which mediates regulation by iron of ferritin translation. An RNA gel retardation assay was used to demonstrate the affinity of a specific cytosolic binding protein for the IRE. A single-base deletion in the IRE eliminated both the interaction of the cytoplasmic protein with the IRE and translational regulation. Thus, the regulatory potential of the IRE correlates with its capacity to specifically interact with proteins. Titration curves of binding activity after treatment of cells with an iron chelator suggest that the factor acts as a repressor of ferritin translation.
Platelet-Derived Growth Factor A Chain Is Maternally Encoded in
Xenopus
Embryos
Authors: Mercola M. , Melton D. A. , Stiles C. D.
Published: October 2006

Transcription of zygotic genes does not occur in early
Xenopus
embryos until the mid-blastula transition, 6 to 7 hours after fertilization. Before this time, development is directed by maternal proteins and messenger RNAs stored within the egg. Two different forms of the A chain of platelet-derived growth factor (PDGF) are shown here to be encoded by maternal messenger RNAs. The two forms closely resemble human PDGF; however, the long form contains a hydrophobic region near the carboxyl terminus. The presence of PDGF messenger RNA in the embryo supports the idea that endogenous growth factors act at the earliest stages of embryogenesis.
A Quantitative Bioassay for HIV-1 Based on Trans-Activation
Authors: Felber Barbara K. , Pavlakis George N.
Published: October 2006

A bioassay that is based on trans-activation has been developed for the detection and quantitation of the human immunodeficiency virus type 1 (HIV-1). Indicator cell lines were constructed that contain the HIV-1 long terminal repeat ligated to the chloramphenicol acetyltransferase (CAT) gene. Infection of these cells by HIV activates the expression of CAT protein. Isolates of HIV-1 with divergent nucleotide sequences activated the indicator cell lines to a similar extent, approximately 500- to 1000-fold. Human T cell lymphotropic viruses types 1 and 2, equine infectious anemia virus, and herpes simplex virus 1 did not activate the indicator cell lines. Isolates of simian immunodeficiency virus and human T cell lymphotropic virus type 4 activated these cells to a much lesser extent, which suggests that these viruses contain similar, but distinct, trans-activators. This assay can be used for the detection, quantitation, and typing of HIV and for studying the effect of drugs on the replication of HIV in different cellular backgrounds.
Computer Use in Diagnosis, Prognosis, and Therapy
Authors: Schoolman Harold M. , Bernstein Lionel M.
Published: October 2006

Computers are used to influence diagnostic and therapeutic decisions. The computer's information-handling capabilities allow it to serve as a reliable extension of the physician's memory and expander of the physician's information and synthesized knowledge resources. Computers have been used to facilitate decisions through organization of patient data, improved classification of patients, decision analysis in clinical settings, and simulation of expert clinical reasoning. Computer programs are more successful in narrow, constrained, single arenas of medicine with much underlying pathophysiologic understanding and where decisions are based largely on hard laboratory data. New models of synthetic reasoning that simulate expert clinical behavior show promise of supporting complicated decisions concerning problems of multiple diseases. All systems are confronted by problems of consensus and authority of the underlying information used.
Evidence for the Involvement of
GM-CSF
and
FMS
in the Deletion (5q) in Myeloid Disorders
Authors: Le Beau Michelle M. , Westbrook Carol A. , Diaz Manuel O. , Larson Richard A. , Rowley Janet D. , Gasson Judith C. , Golde David W. , Sherr Charles J.
Published: October 2006

By in situ chromosomal hybridization, the
GM-CSF
and
FMS
genes were localized to human chromosome 5 at bands q23 to q31, and at band 5q33, respectively. These genes encode proteins involved in the regulation of hematopoiesis, and are located within a chromosome region frequently deleted in patients with neoplastic myeloid disorders. Both genes were deleted in the 5q- chromosome from bone marrow cells of two patients with refractory anemia and a del(5)(q15q33.3). The
GM-CSF
gene alone was deleted in a third patient with acute nonlymphocytic leukemia (ANLL) who has a smaller deletion, del(5)(q22q33.1). Leukemia cells from a fourth patient who has ANLL and does not have a del(5q), but who has a rearranged chromosome 5 that is missing bands q31.3 to q33.1 [ins(21;5)(q22;q31.3q33.1)] were used to sublocalize these genes; both genes were present on the rearranged chromosome 5. Thus, the deletion of one or both of these genes may be important in the pathogenesis of myelodysplastic syndromes or of ANLL.
Extended Culture of Mouse Embryo Cells Without Senescence: Inhibition by Serum
Authors: Loo Deryk T. , Fuquay Janice I. , Rawson Cathleen L. , Barnes David W.
Published: October 2006

Mouse embryo cells cultured in vitro in serum-supplemented media undergo growth crisis, resulting in the loss of genomically normal cells prior to the appearance of established, aneuploid cell lines. Mouse embryo cells established and maintained for multiple passages in the absence of serum did not exhibit growth crisis or gross chromosomal aberration. Cells cultured under these conditions were dependent on epidermal growth factor for survival. Proliferation was reversibly inhibited by serum or platelet-free plasma, suggesting that mouse embryo cultures maintained by conventional procedures are under the influence of inhibitory factors.
Differential Expression of c-
myb
mRNA in Murine B Lymphomas by a Block to Transcription Elongation
Authors: Bender Timothy P. , Thompson Craig B. , Kuehl W. Michael
Published: October 2006

Expression of c-
myb
proto-oncogene messenger RNA (mRNA) and protein has been detected principally in tumors and in normal tissue of hematopoietic origin. In each hematopoietic lineage examined, expression of the c-
myb
gene is markedly downregulated during hematopoietic maturation. However, the mechanism by which differential expression of the c-
myb
gene is regulated is not known. In murine B-lymphoid tumor cell lines, the amount of steady-state c-
myb
mRNA is 10 to more than 100 times greater in pre-B cell lymphomas than in B cell lymphomas and plasmacytomas. The downregulation of c-
myb
mRNA correlates with events at the pre-B cell-B cell junction. Differential expression of c-
myb
mRNA levels detected between a pre-B cell lymphoma and a mature B cell lymphoma is now shown to be mediated by a block to transcription elongation in the first intron of the c-
myb
locus. In addition, this developmentally regulated difference in transcriptional activity is correlated with alterations in higher order chromatin structure as reflected by changes in the patterns of hypersensitivity to deoxyribonuclease I at the 5′ end of the c-
myb
transcription unit. Regulation of transcription elongation may provide a more sensitive mechanism for rapidly increasing and decreasing mRNA levels in response to external stimuli than regulation of the initiation of transcription.
Uromodulin (Tamm-Horsfall Glycoprotein): a Renal Ligand for Lymphokines
Authors: Hession Catherine , Decker Jean M. , Sherblom Anne P. , Kumar Satish , Yue Cho C. , Mattaliano Robert J. , Tizard Richard , Kawashima Eric , Schmeissner Ursula , Heletky Sheryl , Chow E. Pingchang , Burne Cynthia A. , Shaw Alan , Muchmore Andrew V.
Published: October 2006

The protein portion of the immunosuppressive glycoprotein uromodulin is identical to the Tamm-Horsfall urinary glycoprotein and is synthesized in the kidney. Evidence that the glycoproteins are the same is based on amino acid sequence identity, immunologic cross-reactivity, and tissue localization to the thick ascending limb of Henle's loop. Nucleic acid sequencing of clones for uromodulin isolated from a complementary DNA bank from human kidney predicts a protein 639 amino acids in length, including a 24-amino acid leader sequence and a cysteine-rich mature protein with eight potential glycosylation sites. Uromodulin and preparations of Tamm-Horsfall glycoprotein bind to recombinant murine interleukin-1 (rIL-1) and human rIL-1α, rIL-1β, and recombinant tumor necrosis factor (rTNF). Uromodulin isolated from urine of pregnant women by lectin adherence is more immunosuppressive than material isolated by the original salt-precipitation protocol of Tamm and Horsfall. Immunohistologic studies demonstrate that rIL-1 and rTNF bind to the same area of the human kidney that binds to antiserum specific for uromodulin. Thus, uromodulin (Tamm-Horsfall glycoprotein) may function as a unique renal regulatory glycoprotein that specifically binds to and regulates the circulating activity of a number of potent cytokines, including IL-1 and TNF.
Lectin Activation in
Giardia lamblia
by Host Protease: a Novel Host-Parasite Interaction
Authors: Lev Boaz , Ward Honorine , Keusch Gerald T. , Pereira Miercio E.
Published: October 2006

A lectin in
Giardia lamblia
was activated by secretions from the human duodenum, the environment where the parasite lives. Incubation of the secretions with trypsin inhibitors prevented the appearance of lectin activity, implicating proteases as the activating agent. Accordingly, lectin activation was also produced by crystalline trypsin and Pronase; other proteases tested were ineffective. When activated, the lectin agglutinated intestinal cells to which the parasite adheres in vivo. The lectin was most specific to mannose-6-phosphate and apparently was bound to the plasma membrane. Activation of a parasite lectin by a host protease represents a novel mechanism of host-parasite interaction and may contribute to the affinity of
Giardia lamblia
to the infection site.
Two-Dimensional Nuclear Magnetic Resonance Spectroscopy
Authors: Bax Ad , Lerner Laura
Published: October 2006

Great spectral simplification can be obtained by spreading the conventional one-dimensional nuclear magnetic resonance (NMR) spectrum in two independent frequency dimensions. This so-called two-dimensional NMR spectroscopy removes spectral overlap, facilitates spectral assignment, and provides a wealth of additional information. For example, conformational information related to interproton distances is available from resonance intensities in certain types of two-dimensional experiments. Another method generates
1
H NMR spectra of a preselected fragment of the molecule, suppressing resonances from other regions and greatly simplifying spectral appearance. Two-dimensional NMR spectroscopy can also be applied to the study of
13
C and
15
N, not only providing valuable connectivity information but also improving sensitivity of
13
C and
15
N detection by up to two orders of magnitude.
Enkephalin-Containing Neurons Visualized in Spinal Cord Cell Cultures
Authors: Neale Joseph H. , Barker Jeffery L. , Uhl George R. , Snyder Solomon H.
Published: October 2006

Neuronal cells, axons, and terminals containing immunoreactive enkephalin have been visualized in cultures of dissociated fetal spinal cord. These cultures may provide a valuable system in which to explore the effects of chronic drug treatment on the physiology of enkephalin-containing cells and their interactions with other cells.
Speech Perception Takes Precedence Over Nonspeech Perception
Authors: Whalen D. H. , Liberman Alvin M.
Published: October 2006

Some components of a speech signal, when made more intense, are heard simultaneously as speech and nonspeech—a form of duplex perception. At lower intensities, the speech alone is heard. Such intensity-dependent duplexity implies the existence of a phonetic mode of perception that takes precedence over auditory modes.
Functional Regions of the Envelope Glycoprotein of Human Immunodeficiency Virus Type 1
Authors: Kowalski Mark , Potz Joseph , Basiripour Ladan , Dorfman Tatyana , Goh Wei Chun , Terwilliger Ernest , Dayton Andrew , Rosen Craig , Haseltine William , Sodroski Joseph
Published: October 2006

The envelope of the human immunodeficiency virus type 1 (HIV-1) plays a central role in the process of virus entry into the host cell and in the cytopathicity of the virus for lymphocytes bearing the CD4 molecule. Mutations that affect the ability of the envelope glycoprotein to form syncytia in CD4
+
cells can be divided into five groups: those that decrease the binding of the envelope protein to the CD4 molecule, those that prevent a post-binding fusion reaction, those that disrupt the anchorage of the envelope glycoprotein in the membrane, those that affect the association of the two subunits of the envelope glycoprotein, and those that affect post-translational proteolytic processing of the envelope precursor protein. These findings provide a functional model of the HIV envelope glycoprotein.
Induction of the c-
fos
Oncogene by Thyrotropic Hormone in Rat Thyroid Cells in Culture
Authors: Colletta Giulia , Cirafici Anna Maria , Vecchio Giancarlo
Published: October 2006

Rat thyroid cells in culture, rendered quiescent by hormone deprivation, can be stimulated to undergo DNA synthesis in the absence of serum by the addition of purified thyrotropin. The primary effect in response to thyrotropin action in thyroid cells is the induction of the c-
fos
oncogene, followed by c-
myc
expression. This suggests that thyrotropin acts as a competence growth factor.
Transition State Analogs as Ligands for Affinity Purification of Juvenile Hormone Esterase
Authors: Abdel-Aal Yehia A. I. , Hammock Bruce D.
Published: October 2006

Insect juvenile hormones are metabolized in numerous species of caterpillars by low abundance, highly specific esterases. Because of their role in regulating and possibly disrupting juvenile hormone titer and thus insect metamorphosis, they are of interest to developmental biologists as well as scientists interested in selective insect control. However, the enzymes have defied attempts to purify and characterize them. Juvenile hormone esterase activity can be inhibited by a variety of 3-substituted 1,1,1-trifluoropropanone sulfides. These apparent transition state analogs were used as ligands and eluting agents to purify juvenile hormone esterase from four insect species from 500-fold to over 1000-fold in high yield. After elution from the affinity column, the enzymes were radiolabeled with paraoxon and analyzed by electrophoresis, and the results demonstrate a high degree of purity. Transition state analogs may be useful for the affinity purification of other enzymes.
Nerve Growth Factor Gene Expression in the Developing Rat Brain
Authors: Large Thomas H. , Bodary Sarah C. , Clegg Dennis O. , Weskamp Gisela , Otten Uwe , Reichardt Louis F.
Published: October 2006

The regulation of nerve growth factor (NGF) protein and NGF messenger RNA (mRNA) in the developing rat brain has been studied to assess the hypothesis that NGF supports the differentiation of cholinergic neurons in the basal forebrain. In the adult, the major targets of these neurons, the hippocampus and neocortex, contain the highest concentrations of NGF mRNA, but comparatively low ratios of NGF protein to its mRNA. In contrast, a high concentration of NGF protein and a low concentration of NGF mRNA were seen in the basal forebrain, consistent with retrograde transport of NGF protein into this region from the neocortex and hippocampus. In these two target regions NGF and NGF mRNA were barely detectable at birth, their concentrations increased to a peak at day 21, and then NGF mRNA, but not NGF protein, declined threefold by day 35. NGF accumulation in the basal forebrain paralleled that in the target regions and preceded an increase in choline acetyltransferase, suggesting that the differentiation of cholinergic projection neurons is indeed regulated by retrogradely transported NGF. In addition, high ratios of NGF protein to NGF mRNA, comparable to that in the basal forebrain, were seen in the olfactory bulb and cerebellum, suggesting that NGF may be transported into these regions by unidentified neurons.
Shock and Tissue Injury Induced by Recombinant Human Cachectin
Authors: Tracey Kevin J. , Beutler Bruce , Lowry Stephen F. , Merryweather James , Wolpe Stephen , Milsark Ian W. , Hariri Robert J. , Fahey Thomas J. , Zentella Alejandro , Albert James D. , Shires G. Tom , Cerami Anthony
Published: October 2006

Cachectin (tumor necrosis factor), a protein produced in large quantities by endotoxin-activated macrophages, has been implicated as an important mediator of the lethal effect of endotoxin. Recombinant human cachectin was infused into rats in an effort to determine whether cachectin, by itself, can elicit the derangements of host physiology caused by administration of endotoxin. When administered in quantities similar to those produced endogenously in response to endotoxin, cachectin causes hypotension, metabolic acidosis, hemoconcentration, and death within minutes to hours, as a result of respiratory arrest. Hyperglycemia and hyperkalemia were also observed after infusion. At necropsy, diffuse pulmonary inflammation and hemorrhage were apparent on gross and histopathologic examination, along with ischemic and hemorrhagic lesions of the gastrointestinal tract, and acute renal tubular necrosis. Thus, it appears that a single protein mediator (cachectin) is capable of inducing many of the deleterious effects of endotoxin.
Lactate Transporter Defect: A New Disease of Muscle
Authors: Fishbein William N.
Published: October 2006

New methods were used to identify the abnormality in a patient who showed evidence of neuromuscular dysfunction on extensive clinical examination. The methods revealed that the lactate content of the patient's skeletal muscle does not decline normally after exercise and that his red cells are defective in lactate transport. These results suggest that skeletal muscle and erythrocyte membranes share the same genetic lactate transporter (or a common subunit), which is deficient in this patient. This defect may be a common cause of elevated serum creatine kinase levels, as seen in the patient described here and of unexplained episodes of rhabdomyolysis and myoglobinuria.
Sperm Diaphorase: Genetic Polymorphism of a Sperm-Specific Enzyme in Man
Authors: Caldwell Kevin , Blake Edward T. , Sensabaugh G. F.
Published: October 2006

Human sperm contains en enzyme with diaphorase activity that appears to be unique to sperm. Electrophoretic analysis of the diaphorase activity in sperm of different individuals reveals three phenotypic patterns. This polymorphism can be explained in terms of two alleles segregating at an autosomal locus; the allele frequencies have been determined to be 0.71 and 0.29. This appears to be the first reported example of a sperm-specific genetic polymorphism in man; its existence raises a number of genetic and biochemical questions.
Human von Willebrand Factor (vWF): Isolation of Complementary DNA (cDNA) Clones and Chromosomal Localization
Authors: Ginsburg David , Handin Robert I. , Bonthron David T. , Donlon Timothy A. , Bruns Gail A. P. , Latt Samuel A. , Orkin Stuart H.
Published: October 2006

Human factor VIII—von Willebrand factor (vWF) is a large, multimeric glycoprotein that plays a central role in the blood coagulation system, serving both as a carrier for factor VIIIC (antihemophilic factor) and as a major mediator of platelet-vessel wall interaction. Diminished or abnormal vWF activity results in von Willebrand's disease (vWD), a common and complex hereditary bleeding disorder. Overlapping vWF cDNA clones that span 8.2 kilobases of the vWF messenger RNA have been obtained. vWF accounts for approximately 0.3 percent of endothelial cell messenger RNA and was undetectable in several other tissues examined. A large single copy gene for vWF is located on the short arm of chromosome 12 (12p12 → 12pter). No gross gene rearrangement or deletion was detected in the DNA of two patients with severe vWD.
Human Recombinant Granulocyte-Macrophage Colony-Stimulating Factor: A Multilineage Hematopoietin
Authors: Sieff Colin A. , Emerson Stephen G. , Donahue Robert E. , Nathan David G. , Wang Elizabeth A. , Wong Gordon G. , Clark Steven C.
Published: October 2006

Human recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) was tested for its ability to induce colony formation in human bone marrow that had been enriched for progenitor cells. In addition to its expected granulocyte-monocyte colony-stimulating activity, the recombinant GM-CSF had burst-promoting activity for erythroid burst-forming units and also stimulated colonies derived from multipotent (mixed) progenitors. In contrast, recombinant erythroid-potentiating activity did not stimulate erythroid progenitors. The experiments prove that human GM-CSF has multilineage colony-stimulating activity.
The "Spliceosome": Yeast Pre-Messenger RNA Associates with a 40
S
Complex in a Splicing-Dependent Reaction
Authors: Brody Edward , Abelson John
Published: October 2006

The in vitro splicing reactions of pre-messenger RNA (pre-mRNA) in a yeast extract were analyzed by glycerol gradient centrifugation. Labeled pre-mRNA appears in a 40
S
peak only if the pre-mRNA undergoes the first of the two partial splicing reactions. RNA analysis after extraction of glycerol gradient fractions shows that lariat-form intermediates, molecules that occur only in mRNA splicing, are found almost exclusively in this 40
S
complex. Another reaction intermediate, cut 5′ exon RNA, can also be found concentrated in this complex. The complex is stable even in 400 m
M
KCl, although at this salt concentration, it sediments at 35
S
and is clearly distinguishable from 40
S
ribosomal subunits. This complex, termed a "spliceosome," is thought to contain components necessary for mRNA splicing; its existence can explain how separated exons on pre-mRNA are brought into contact.
Passive Immunization Against Cachectin/Tumor Necrosis Factor Protects Mice from Lethal Effect of Endotoxin
Authors: Beutler B. , Milsark I. W. , Cerami A. C.
Published: October 2006

A highly specific polyclonal rabbit antiserum directed against murine cachectin/tumor necrosis factor (TNF) was prepared. When BALB/c mice were passively immunized with the antiserum or with purified immune globulin, they were protected against the lethal effect of the endotoxin lipopolysaccharide produced by
Escherichia coli
. The prophylactic effect was dose-dependent and was most effective when the antiserum was administered prior to the injection of the endotoxin. Antiserum to cachectin/TNF did not mitigate the febrile response of endotoxin-treated animals, and very high doses of endotoxin could overcome the protective effect. The median lethal dose of endotoxin in mice pretreated with 50 microliters of the specific antiserum was approximately 2.5 times greater the median lethal dose for controls given nonimmune serum. The data suggest that cachectin/TNF is one of the principal mediators of the lethal effect of endotoxin.
Cerebellar Vermis: Essential for Long-Term Habituation of the Acoustic Startle Response
Authors: Leaton Robert N. , Supple William F.
Published: October 2006

The acoustic startle response in rats shows both short-term habituation, which recovers in seconds or minutes, and long-term habituation, which is effectively permanent. Lesions of the cerebellar vermis significantly attenuated long-term habituation without affecting the short-term process or altering initial response levels. In this response system the cerebellar vermis is part of an essential circuit for long-term habituation.
Vaccination Against
Schistosoma mansoni
with Purified Surface Antigens
Authors: Smith Maire A. , Clegg John A.
Published: October 2006

Two surface antigens were isolated from young or adult schistosomes by affinity chromatography with monoclonal antibodies. Vaccination with an antigen having a molecular weight of 155,000 gave partial protection against challenge in some batches of mice and in a group of cynomolgus monkeys. Vaccination with an antigen having a molecular weight of 53,000 gave similar levels of protection in mice. The results demonstrate that protection can be obtained with single antigens, but the precise requirements for reproducible vaccination are as yet unknown.
Molecular Structure of Troponin C from Chicken Skeletal Muscle at 3-Angstrom Resolution
Authors: Sundaralingam M. , Bergstrom R. , Strasburg G. , Rao S. T. , Roychowdhury P. , Greaser M. , Wang B. C.
Published: October 2006

The x-ray structure of chicken skeletal muscle troponin C (TnC), the Ca
2+
-binding subunit of the troponin complex, shows that the protein is about 70 angstroms long with an unusual dumbbell shape. The carboxyl and amino domains are separated by a single long α helix of about nine turns. Only the two high-affinity Ca
2+
-Mg
2+
sites of the COOH-domain are occupied by metal ions resulting in conformational differences between the COOH- and NH
2
-domains. These differences are probably important in the triggering of muscle contraction by TnC. Also the structure of TnC is relevant in understanding the function of other calcium-regulated proteins, in particular that of calmodulin because of its strong similarity in amino acid sequence.
Transformation of Human Bronchial Epithelial Cells Transfected by Harvey
ras
Oncogene
Authors: Yoakum George H. , Lechner John F. , Gabrielson Edward W. , Korba Brent E. , Malan-Shibley Louise , Willey James C. , Valerio Marion G. , Shamsuddin Abulkalam M. , Trump Benjamin F. , Harris Curtis C.
Published: October 2006

Transfection of normal human bronchial epithelial (NHBE) cells with a plasmid carrying the
ras
oncogene of Harvey murine sarcoma virus (v-Ha
ras
) changed the growth requirements, terminal differentiation, and tumorigenicity of the recipient cells. One of the cell lines isolated after transfection (TBE-1) was studied extensively and shown to contain v-Ha
ras
DNA. Total cellular RNA from TBE-1 cells hybridized to v-Ha
ras
structural gene fragment probes five to eight times more than RNA from parental NHBE cells. The TBE-1 cells expressed phosphorylated v-Ha
ras
polypeptide p21, showed a reduced requirement for growth-factor supplements, and became aneuploid as an early cellular response to v-Ha
ras
expression. As the transfectants acquire an indefinite life-span and anchorage independence they became transplantable tumor cells and showed many phenotypic changes suggesting a pleiotropic mechanism for the role of Ha
ras
in human carcinogenesis.
Computerized Pattern Recognition: A New Technique for the Analysis of Chemical Communication
Authors: Smith Amos B. , Belcher Anne M. , Epple Gisela , Jurs Peter C. , Lavine Barry
Published: October 2006

Computerized pattern recognition techniques can be applied to the study of complex chemical communication systems. Analysis of high resolution gas chromatographic concentration patterns of the major volatile components of the scent marks of a South American primate,
Saguinus fuscicollis
, demonstrates that the concentration patterns can be used to predict the gender and subspecies of unknown donors.
A Sexually Dimorphic Nucleus in the Human Brain
Authors: Swaab D. F. , Fliers E.
Published: October 2006

A sexually dimorphic cell group is described in the preoptic area of the human hypothalamus. Morphometric analysis revealed that the volume of this nucleus is 2.5 ± 0.6 times (mean ± standard error of the mean) as large in men as in women, and contains 2.2 ± 0.5 times as many cells. Between the ages of 10 and 93 years, the nucleus decreases greatly in volume and in cell number. Although no function has yet been established for this nucleus, it is located within an area that is essential for gonadotropin release and sexual behavior in other mammals.