bluuebunny/crossref_metadata_2025 huggingface dataset:
Attachment of an anti-receptor antibody to non-target cells renders them susceptible to lysis by a clone of cytotoxic T lymphocytes.
Authors: Kranz D M , Tonegawa S , Eisen H N
Published: May 2006

The molecular basis for the dependence of antigen recognition by T cells on products of the major histocompatibility complex (MHC) is unknown, and the antigenic structures that are actually bound by T-cell receptors are ill-defined. In this study, we asked whether a monoclonal antibody (mAb) that reacts with the T-cell receptor of a clone of murine cytotoxic T lymphocytes (CTL) and not with the receptors of other CTL clones can substitute for that clone's natural ligand in specific cytolytic reactions. To answer the question, a mAb (1B2) to the receptor of a CTL clone (2C) was attached covalently to 51Cr-labeled cells that were not otherwise susceptible to lysis by clone 2C, and the cells thus modified were then tested as targets for clone 2C and other CTL clones of similar specificity. All labeled cells modified in this way, including a murine cell line that expresses no cell-surface MHC class I molecules and a human cell line, were lysed by clone 2C but not by other CTL clones. If, however, instead of attaching the mAb to the receptor of clone 2C, the cells were modified by attaching to them mAbs to other surface antigens on CTL [lymphocyte function-associated antigen (LFA-1), Thy-1.2], they were not lysed. In cytolytic titrations, the cells that had been converted by attachment of mAb 1B2 into specific targets for clone 2C were just as susceptible to lysis by that clone as the clone's natural H-2d targets (e.g., P815 cells). However, some accessory surface molecules (LFA-1, Lyt-2) that are required for clone 2C to lyse its natural H-2d targets seemed not to be required for this clone to lyse the mAb-converted target cells. By demonstrating that a variety of different cell types can be thus converted into target cells for CTL, the approach described in this study may provide opportunities to analyze further the mechanisms by which CTL destroy target cells.
Transplantation of human or rodent tumors into cyclosporine-treated mice: a feasible model for studies of tumor biology and chemotherapy.
Authors: Fingert H J , Treiman A , Pardee A B
Published: May 2006

Total growth of transplanted human or rodent tumors in the subrenal capsule of mice was much improved by treatment with cyclosporine (CSA, cyclosporin A). Tumor size increased rapidly between days 6 and 12 after implantation, CSA injected on days 1-5 or 2-8 prevented tumor regression. In contrast, immunologic regression occurred after 6 days in absence of the drug. Tumor growth was comparable in CSA-treated mice, athymic nude mice with human tumors, or normal mice with syngeneic rodent tumors. Studies with rodent tumors in syngeneic mice showed that the CSA treatments had no antitumor effect. Inflammatory infiltration was seen on days 6-12 after tumor implantation into control mice. Immunoperoxidase staining showed murine T cells to be prominent in the infiltrate. In contrast, tumors in CSA-treated mice contained minimal inflammatory infiltrate even 12 days after implantation. Allogeneic tumors in CSA-treated mice caused neovascularization, metastases, and local invasion into the kidney. cis-Diamminedichloroplatinum showed highly significant activity against human tumors in CSA-treated mice during the period 6-10 days after tumor implantation but showed no statistically significant antitumor activity 0-6 days after implantation in mice not treated with CSA. We suggest that in CSA-treated mice the subrenal capsule assay for tumor growth provides a rapid, economical model for investigations in vivo of mouse or human tumor biology, for drug screening with a standard tumor, or for determination of optimal treatment of particular human tumors.
Transcription of ground-state density-functional theory into a local thermodynamics.
Authors: Ghosh S K , Berkowitz M , Parr R G
Published: May 2006

The concepts of local temperature, local entropy, and local free energy density are introduced within the framework of the ground-state density-functional theory of many-electron systems, and a complete local thermodynamic picture is then developed. A view emerges of the electron cloud, as analogous to a classical inhomogeneous fluid moving under gradients of temperature, pressure, and an effective potential, described by a locally Maxwellian distribution.
The membrane glycoprotein encoded by the retroviral oncogene v-erb-B is structurally related to tyrosine-specific protein kinases.
Authors: Privalsky M L , Ralston R , Bishop J M
Published: May 2006

Avian erythroblastosis virus can transform both fibroblasts and erythroid cells to neoplastic growth. A locus within the virus genome, v-erb B, encodes a membrane glycoprotein essential for the oncogenic properties of the virus. No biochemical function has until now been attributed to the v-erb B protein. We report here that the v-erb B glycoprotein shares strong structural homologies with the tyrosine-specific protein kinases encoded by certain retroviral oncogenes. The patterns of amino acid conservation between the tyrosine-specific protein kinases and the v-erb B protein, and between the v-erb B protein and the catalytic subunit of bovine protein kinase, suggest a possible functional as well as structural relatedness.
Brain-specific genes have identifier sequences in their introns.
Authors: Milner R J , Bloom F E , Lai C , Lerner R A , Sutcliffe J G
Published: May 2006

The 82-nucleotide identifier (ID) sequence is present in the rat genome in 1-1.5 X 10(5) copies and in cDNA clones of precursors of brain-specific mRNAs. One brain-specific gene contains more than one ID sequence in its introns. There is an excess of ID sequences to brain genes, and some ID sequences appear to have been inserted as mobile elements into other genetic locations. Therefore, brain genes contain ID sequences in their introns, but not all ID sequences are located in brain gene introns. A brain ID consensus sequence has been obtained by comparing 8 ID nucleotide sequences.
Glucocorticoid inhibition of initiation of transcription of the DNA encoding rRNA (rDNA) in lymphosarcoma P1798 cells.
Authors: Cavanaugh A H , Gokal P K , Lawther R P , Thompson E A
Published: May 2006

Cell-free extracts of lymphosarcoma P1798 cell culture lines support faithful initiation upon the cloned mouse DNA encoding rRNA (rDNA) promoter, whereas extracts from cells treated for 16 hr with 0.1 microM dexamethasone cannot. Extracts from both sources transcribe the cloned 5S RNA gene in vitro and mixing experiments further demonstrate that inhibition of transcription of rDNA in vitro is not due to nucleases or inhibitors of transcription present in extracts from glucocorticoid-treated cells. Incubation of extracts from control cells at 45 degrees C for 15 min inactivates RNA polymerase I and abolishes transcription. Activity can be restored by the addition of partially purified RNA polymerase I from control cells and hormone-treated cells. Moreover, extracts from hormone treated cells can be reconstituted by the addition of a partially purified, heat-stable transcription factor from control cells.
Benzodiazepines that bind at peripheral sites inhibit cell proliferation.
Authors: Wang J K , Morgan J I , Spector S
Published: May 2006

[3H]Ro5-4864 binds to mouse thymoma cells in a specific, saturable, and reversible manner. Scatchard analysis shows a single class of binding sites with a Kd of 4.4 nM and a Bmax of 477 fmol per 10(6) cells. This benzodiazepine binding site is of the peripheral type, based on the relative potencies of Ro5-4864 and clonazepam in competing for [3H]diazepam binding. Fifteen benzodiazepines that bind to this site with affinities ranging from 6 nM to 1 microM also reversibly inhibit the proliferation of thymoma cells in culture at the micromolar dose range. There is a strong positive correlation (r = 0.85) between the binding constants of these compounds for the peripheral-type sites and their ED50 in inhibiting the uptake of [3H]thymidine into the cells. These sites may be involved in the regulation of thymoma cell proliferation.
Interferon gamma blocks the growth of Toxoplasma gondii in human fibroblasts by inducing the host cells to degrade tryptophan.
Authors: Pfefferkorn E R
Published: May 2006

Treatment of human fibroblasts with human recombinant gamma interferon blocked the growth of Toxoplasma gondii, an obligate intracellular protozoan parasite. Growth of the parasite was measured by a plaque assay 7 days after infection or by the incorporation of [3H]uracil 1 or 2 days after infection. The antitoxoplasma activity induced in the host cells by gamma interferon was strongly dependent upon the tryptophan concentration of the medium. Progressively higher minimal inhibitory concentrations of gamma interferon were observed as the tryptophan concentration in the culture medium was increased. Treatment with gamma interferon did not make the cells impermeable to tryptophan. The kinetics of [3H]tryptophan uptake into the acid-soluble pools of control and gamma interferon-treated cultures were identical during the first 48 sec. Thereafter uptake of [3H]tryptophan into the acid-soluble pool of control fibroblasts reached the expected plateau after 96 sec. In contrast, uptake of [3H]tryptophan continued for at least 12 min in the gamma interferon-treated cultures. At that time, the acid-soluble pool of the gamma interferon-treated cultures contained 8 times the radioactivity of the control cultures. This continued accumulation was the result of rapid intracellular degradation of [3H]tryptophan into kynurenine and N-formylkynurenine that leaked slowly from the cells. These two metabolites were also recovered from the medium of cultures treated for 1 or 2 days with gamma interferon. Human recombinant alpha and beta interferons, which have no antitoxoplasma activity, did not induce any detectable degradation of tryptophan. Several hypotheses are presented to explain how the intracellular degradation of tryptophan induced by gamma interferon could restrict the growth of an obligate intracellular parasite.
Comparison of immunity to malaria in Sudan and Indonesia: crisis-form versus merozoite-invasion inhibition.
Authors: Jensen J B , Hoffman S L , Boland M T , Akood M A , Laughlin L W , Kurniawan L , Marwoto H A
Published: May 2006

Immunity to falciparum malaria was compared in two populations from malarious areas of southern Sudan and Flores, Indonesia. In Sudan, splenomegaly in adults was rare and anti-plasmodium indirect fluorescent antibody (IFA) titers were low to moderate, 1:1,280 being the modal titer. Sudanese serum was profoundly inhibitory to cultured Plasmodium falciparum, reducing incorporation of radiolabeled hypoxanthine by 63-93% and severely retarding intraerythrocytic parasite development, resulting in moribund crisis-form parasites and virtually no healthy schizonts. In Flores, 64% of the serum donors had splenomegaly greater than or equal to Hackett spleen grade 4 or 5, and the modal IFA titer was 1:10,240. Sera from Indonesia did not retard intraerythrocytic parasite development, but inhibited merozoite erythrocyte invasion 22-87%. Anti-merozoite activity did not correlate with IFA titers. The differences in principal modes of anti-parasitic activity suggest that immunity to malaria in Sudan is based on cell-mediated immune mechanisms associated with crisis forms, merozoite neutralization being of secondary importance. In contrast, malaria immunity in Flores appears to be principally based on anti-merozoite antibody, which does not cause crisis forms and allows for development of reduced numbers of healthy schizonts. This less efficient mechanism may lead to a continuous low-grade parasitemia, which could explain the high specific malaria antibody titers and adult splenomegaly in Flores as compared to Sudan. This latter approach to immunity, being less efficient than the former, apparently results in chronic malaria infections with associated high Ig titers and splenomegaly.
A glioma-derived analog to platelet-derived growth factor: demonstration of receptor competing activity and immunological crossreactivity.
Authors: Nistér M , Heldin C H , Wasteson A , Westermark B
Published: May 2006

A human clonal glioma cell line, U-343 MGa Cl 2, cultured under serum-free conditions, was found to release a factor that competed with 125I-labeled platelet-derived growth factor (125I-PDGF) for binding to human foreskin fibroblasts. The concentration of competing activity in conditioned medium was equal to 20-30 ng of PDGF per ml. The PDGF receptor competing activity had an elution position on Sephadex G-200 close to that of tracer PDGF. The same fractions in the chromatogram also contained growth-promoting activity and material active in a PDGF radioimmunoassay. Incubation of partially purified, 125I-labeled glioma factor with fibroblasts, or rabbit anti-PDGF serum, led to the selective binding of a component with an estimated Mr of 31,000, as shown by NaDodSO4/gel electrophoresis under nonreducing conditions. After reduction this component migrated as a Mr 18,000 protein. Thus, the behavior in NaDodSO4/gel electrophoresis was similar to that of PDGF. Furthermore, incubation of partially purified glioma factor with immobilized PDGF antibodies markedly decreased the amount of PDGF receptor competing activity remaining in the supernatant. These results suggest that the factor produced by glioma cells has structural, immunological, and functional resemblance to PDGF. We previously reported that a human osteosarcoma cell line produces a PDGF-like molecule with growth-promoting activity. Taken together with the recent finding that PDGF is homologous to the transforming gene product of simian sarcoma virus, our present data give additional support for the idea that an autocrine activation of the PDGF receptor may be operational in the growth of human tumors of mesenchymal or glial origin.
Isolation and identification of enkephalins in pedal ganglia of Mytilus edulis (Mollusca).
Authors: Leung M K , Stefano G B
Published: May 2006

An acid extract of pedal ganglia of the mollusc Mytilus edulis was fractionated by high-pressure liquid chromatography with a reverse-phase column. Peak fractions with retention times of those of [Met]- and [Leu]enkephalin were subjected to binding assays in both invertebrate and vertebrate tissues. The results showed that these fractions have the same binding activities as authentic enkephalins. Peptides from these fractions were purified by high-pressure liquid chromatography under isocratic conditions. Sequential amino acid analyses showed that these peptides have the same primary structures as [Met]- and [Leu]enkephalin. These results with M. edulis suggest that invertebrates possess an enkephalinergic system similar to that of higher organisms.
Two initiation sites detected in the small s1 species of reovirus mRNA by dipeptide synthesis in vitro.
Authors: Cenatiempo Y , Twardowski T , Shoeman R , Ernst H , Brot N , Weissbach H , Shatkin A J
Published: May 2006

Reovirus mRNAs directed the synthesis of fMet dipeptides in a translation initiation system reconstituted from rabbit reticulocyte initiation and elongation factors, Artemia salina 80S ribosomes, yeast fMet-tRNAiMet and Escherichia coli3H-labeled aminoacyl tRNAs. As predicted from the GC(U,G) codon that follows the 5'-proximal AUG in half of the viral mRNA species, fMet-Ala was the predominant dipeptide product obtained in response to a mixture of mRNAs or to the separated size classes of medium (m) and small (s) mRNA. The four individual small mRNA species each directed the synthesis of an fMet dipeptide that was consistent with the utilization of the 5'-proximal AUG for initiation. In addition to fMet-Asp, the s1 mRNA also directed fMet-Glu synthesis indicative of initiation in a second reading frame at the 5'-penultimate AUG. The tripeptide fMet-Glu-Tyr was also synthesized from s1 mRNA, which further verified this second initiation site. mRNAs containing 5'-terminal GpppG were 10-15% as active as the corresponding m7G-capped templates. The dipeptide assay provides a rapid method for determining initiation sites in individual mRNAs or in mixtures of mRNAs.
Insulin stimulation of phospholipid methylation in isolated rat adipocyte plasma membranes.
Authors: Kelly K L , Kiechle F L , Jarett L
Published: May 2006

Partially purified plasma membranes prepared from rat adipocytes contain N-methyltransferase(s) that utilize(s) S-adenosyl-L-methionine to synthesize phosphatidylcholine from phosphatidylethanolamine. The incorporation of [3H]methyl from S-adenosyl-L-[methyl-3H]methionine into plasma membrane phospholipids was linear with incubation time and plasma membrane protein concentration and was inhibited in a dose-dependent manner by both S-adenosyl-L-homocysteine and 3-deazadenosine. The addition of insulin to plasma membranes stimulated the methylation of endogenous phosphatidylethanolamine, as evidenced by an increase in the levels of phosphatidyl-N-monomethylethanolamine, phosphatidyl-N, N-dimethylethanolamine, and phosphatidylcholine. The effect of insulin was rapid and concentration-dependent, with 100 microunits/ml providing near maximal stimulation. The incorporation of [3H]methyl into phospholipids of control and insulin-stimulated plasma membranes was enhanced by the addition of exogenous methyltransferase substrates phosphatidylethanolamine, phosphatidyl-N-monomethylethanolamine, and phosphatidyl-N,N-dimethylethanolamine. The stimulatory effect of insulin on adipocyte plasma membrane phospholipid methylation may have a physiological role in insulin action.
Demonstration of transcriptional regulation of specific genes by phytochrome action
Authors: Silverthorne Jane , Tobin Elaine M.
Published: May 2006

We have developed an
in vitro
transcription system that uses nuclei isolated from
Lemna gibba
G-3. The
in vitro
transcripts include sequences homologous to hybridization probes for the small subunit of ribulose-1,5-bisphosphate carboxylase [3-phospho-D-glycerate carboxy-lyase (dimerizing), EC 4.1.1.39], the light-harvesting chlorophyll
a
/
b
-protein, and rRNA. Light-harvesting chlorophyll
a
/
b
-protein sequences are transcribed to a greater extent in nuclei isolated from plants grown in darkness with 2 min of red light every 8 hr than in nuclei isolated from dark-treated plants. Furthermore, the amount of these transcripts measured in plants given a single minute of red light after dark treatment is increased over the amount measured in dark-treated plants. The effect of red light is at least partially reversible by 10 min of far-red light given immediately after the red light pulse. Transcription of both rRNA and small subunit sequences is also stimulated by a single minute of red light as compared to dark-treated tissue. However, the relative magnitudes of the increases compared to the dark levels are smaller than the increase seen for the chlorophyll
a
/
b
-protein, possibly because of the higher level of transcription of these sequences in the dark. The effect of red light on the transcription of small subunit and rRNA sequences is also reversible by immediate treatment with 10 min of far-red light. Pulse chase studies of dark-treated nuclei for up to 110 min do not show substantial turnover of
in vitro
labeled small subunit and chlorophyll
a
/
b
-protein transcripts. We therefore conclude that phytochrome action has induced specific changes in transcription of these genes.
Glucocorticoid-induced phospholipase A2-inhibitory proteins mediate glucocorticoid teratogenicity in vitro.
Authors: Gupta C , Katsumata M , Goldman A S , Herold R , Piddington R
Published: May 2006

Dexamethasone induces the synthesis of a phospholipase A2-inhibitory protein (PLIP) of molecular weight approximately equal to 55,000 from calf thymus and PLIPs of molecular weights 55,000, 40,000, 28,000, and 15,000 from A/J mouse thymus and from 12-day embryonic B10. A mouse palates. Sufficient quantities of calf thymus PLIP and of the 15,000 molecular weight mouse thymus and palate PLIPs were prepared and tested as inhibitors of programmed cell death in the medial-edge epithelium of single mouse embryonic palatal shelves in culture. All of the proteins tested prevent the loss of the medial-edge epithelium and, thus, produce the teratogenic effects of glucocorticoids in the palatal culture model. This teratogenic action of both PLIP and glucocorticoids is reversed by arachidonic acid, the precursor of prostaglandins and thromboxanes, suggesting that PLIP mediates the effects of glucocorticoids by inhibiting phospholipase A2.
Isolation of cDNA clones for human complement component C2.
Authors: Bentley D R , Porter R R
Published: May 2006

Two cDNA clones for complement component C2 have been isolated from a high-complexity human liver cDNA library by using a mixture of 64 synthetic oligonucleotides as a probe. The 400-base-pair insert of pC201 codes for a region containing the active site serine residue and the secondary substrate binding pocket of the serine protease. This part of C2 is 34% homologous to the corresponding region of the related serine protease factor B and additional similarity is evident from a number of conservative amino acid replacements in this region. The insert of pC201 was used as a specific probe in RNA transfer analysis to determine the size of the C2 mRNA as approximately equal to 2.9 kilobases. Southern blot analysis of genomic DNA of unrelated individuals identified a single C2 locus and showed no cross-hybridization with the factor B locus.
Optimal sequential sampling from two populations.
Authors: Lai T L , Robbins H
Published: May 2006

Given two statistical populations with unknown means, we consider the problem of sampling chi 1, chi 2, ... sequentially from these populations so as to achieve the greatest possible expected value of the sum Sn = chi 1 + ... + chi n. In particular, for normal populations, we obtain the optimal rule and study its properties when the average of the two population means is assumed known, and exhibit an asymptotically optimal rule without assuming any prior knowledge about the population means.
Trypanosome variant-specific glycoproteins: a polygene protein family with multiple folding patterns?
Authors: Lalor T M , Kjeldgaard M , Shimamoto G T , Strickler J E , Konigsberg W H , Richards F F
Published: May 2006

Infection with the African trypanosomes gives rise to relapsing waves of parasitemia in the host. A predominant population of trypanosomes is present in each wave, and such predominant populations are usually serologically distinct from each other. Trypanosomes are covered by an extramembranous, highly antigenic, variant-specific glycoprotein coat that is 15 nm thick. The primary structure of a large portion of the glycoprotein molecule is different in the predominant trypanosome populations of each parasitemic wave. Analysis of the secondary structure potential of five full-length and five partial amino acid sequences of variant-specific glycoproteins from members of the Trypanosoma brucei complex has been carried out. The potentials for alpha-helix, beta-turns, and beta-strand structure have been calculated. A high degree of alpha-helical structure potential is present in all the full-length or partial sequences examined. There is conservation of secondary structure potential in the COOH-terminal 100 amino acids, where both partial and complete conservation of primary amino acid sequence exists. The NH2-terminal regions are rich in alpha-helix potential. However, over large stretches of the middle of the VSG molecules there is wide diversity of secondary structure potential. This suggests that tertiary folding structures may also be different in this region. If these predictions are true, different regions of the variant-specific glycoprotein could be exposed to the solvent in different variant-specific trypanosome serotypes. The implication is that antigenic variation is mediated by a polygene family of glycoproteins containing highly polymorphic regions. These could fold differently and expose different surface regions of the protein to the solvent. This device might reduce immune crossreactivity among members of the variant-specific glycoprotein family.
Estradiol feedback effects on the alpha-subunit mRNA in the sheep pituitary gland: correlation with serum and pituitary luteinizing hormone concentrations.
Authors: Landefeld T , Kepa J , Karsch F
Published: May 2006

The effects of estradiol feedback on pituitary luteinizing hormone (LH) content, serum LH concentration, and in vitro-translated alpha subunit was examined in the ewe. Three animal models were used representing positive, negative, and no estradiol feedback. Two experiments were carried out: (i) anestrous ewes were treated acutely with five Silastic estradiol implants to induce a LH surge (positive feedback) and (ii) ovariectomized ewes were treated chronically with an estradiol implant (negative feedback) or were not treated (no feedback). Pituitary RNA was prepared and translated in a cell-free system; the alpha subunit was identified by immunoprecipitation and NaDodSO4/PAGE. cpm/microgram of RNA and immunoprecipitated growth hormone and prolactin were used to evaluate possible differences in RNA translational efficiencies among the treatment groups. In experiment 1, significantly higher amounts of the alpha subunit were observed in animals exhibiting an estradiol-induced LH surge than in normal anestrous ewes (P less than 0.001). Examination of values from individual animals suggested a correlation between the stage of the LH surge, pituitary LH, and translated alpha subunit. In experiment 2, the amount of alpha subunit observed in animals exposed to chronic estradiol negative feedback was significantly less (P less than 0.005) than that in the untreated ovariectomized animals (no feedback) and no different from that in intact anestrous ewes. These results suggest that both the negative and the positive feedback effects of estradiol include regulation of the amount of alpha-subunit mRNA.
Contact points between transcription machinery and the fibroin gene promoter deduced by functional tests of single-base substitution mutants.
Authors: Hirose S , Takeuchi K , Hori H , Hirose T , Inayama S , Suzuki Y
Published: May 2006

An efficient method for oligonucleotide-directed mutagenesis was developed to construct a set of site-specific mutations by using a mixture of oligodeoxyribonucleotides. With this method, as high as 40% of the tested clones turned out to be desired mutants. Seven single-point mutants were isolated in the "TATA" box region of the fibroin gene. In vitro transcription experiments showed that single-base transversions at the TATA box (A----T at position -29, T----A or G at -28, A----T at -27, and A----T at -26) resulted in decreased promoter activities, whereas A----G transitions at positions -24 and -23 had no effect. The initiation site of transcription was normal in three down-promoter mutants at positions -28 and -26, but the A----T transversions at positions -29 and -27 induced an additional transcription start from position +4. Using 10 single-point mutants obtained as above or by nitrous acid-induced mutagenesis, we have prepared a pair of heteroduplex DNAs consisting of a mutant strand and the wild-type one. The molecules heterozygous at positions -30, -21, and -20 showed reduced transcription activities when the noncoding strand bears the mutation, whereas that at position -26 gave a low activity when the coding strand carries the mutation. Both types of heteroduplex at positions -29, -28, -27, and -17 exhibited decreased activities. These results suggest a transcription machinery contact to a major groove of the DNA helix at the TATA box and region of position -20.
Identification of a sulfate-bearing molecule associated with HLA class II antigens.
Authors: Sant A J , Cullen S E , Schwartz B D
Published: May 2006

The human Ia antigens (DR, DS, and SB), determined by genes contained within the HLA complex on chromosome 6, are glycoprotein heterodimers consisting of a Mr approximately equal to 34,000 alpha chain and a Mr approximately equal to 28,000 beta chain. As a result of studies exploring the possibility that alpha or beta (or both) might be sulfated, a unique component of the oligomeric Ia antigen complex was discovered. When anti-Ia immunoprecipitates from Nonidet P-40 lysates of [35S]sulfate-labeled lymphoid cells were analyzed by NaDodSO4/PAGE, a molecule of considerable size heterogeneity (Mr 40,000-70,000) was observed. This component was present in both anti-DR and anti-DS immunoprecipitates prepared from both human tonsil cells and lymphoblastoid B-cell lines but was not observed in control precipitates or in association with immunoglobulin or class I HLA molecules. Preliminary biochemical studies indicate that this Mr 40,000-70,000 molecule is polyanionic, disperse in molecular weight, and sensitive to protease digestion. The sulfate-bearing moiety of this component was resistant to Pronase but sensitive to chondroitinase ABC, indicating that this molecule belongs to the chondroitin sulfate class of proteoglycans.
Interaction of calcium channel blockers with non-neuronal benzodiazepine binding sites.
Authors: Cantor E H , Kenessey A , Semenuk G , Spector S
Published: May 2006

The ability of calcium channel blockers to displace the binding of benzodiazepine ligands was investigated in rat heart, kidney, and brain. The dihydropyridine calcium channel blockers nifedipine and nitrendipine displaced the binding of the non-neuronal-site ligand [3H]Ro5-4864, but not that of the neuronal-site ligands [3H]flurazepam or [3H]clonazepam. The inhibition was competitive, with Ki values in the micromolar range. Other calcium channel blockers--i.e., verapamil and diltiazem--were inactive at both sites. Thus, non-neuronal benzodiazepines bind to a class of sites that also binds dihydropyridines. This implies a role for benzodiazepines in the mediation of calcium-dependent phenomena.
Biochemical and anatomical effects of antibodies against nerve growth factor on developing rat sensory ganglia.
Authors: Goedert M , Otten U , Hunt S P , Bond A , Chapman D , Schlumpf M , Lichtensteiger W
Published: May 2006

The importance of nerve growth factor (NGF) for the development of sensory ganglia was investigated by injecting rat fetuses (16.50 days of gestation) with a single dose of anti-NGF antiserum. Four months later the treated animals showed a very large decrease in substance P- and somatostatin-like immunoreactivities in dorsal root ganglia and skin with a lesser decrease in trigeminal ganglia. Fluoride-resistant acid phosphatase, substance P-, and somatostatin-like immunoreactivities were greatly decreased in the dorsal horn of the spinal cord. No change in neurotensin- and [Met]enkephalin-like immunoreactivities was observed. The anti-NGF antiserum treatment produced a greater than 90% decrease in the number of unmyelinated dorsal root fibers and a 35% decrease in the total number of myelinated fibers. The loss in myelinated fibers was restricted to small-diameter fibers with no change in large-diameter fibers. No change in taste bud morphology was noted, thereby refuting the proposal that anti-NGF antiserum treatment may represent an animal model for familial dysautonomia. The present results indicate that NGF is a necessary requirement for the normal development of a significant population of prenatal rat dorsal root ganglion cells.
Quantitative autoradiography of beta 1- and beta 2-adrenergic receptors in rat brain.
Authors: Rainbow T C , Parsons B , Wolfe B B
Published: May 2006

We have used quantitative autoradiography to localize in rat brain beta 1- and beta 2-adrenergic receptors. These receptors were labeled in vitro with 125I-labeled pindolol, an antagonist of beta-adrenergic receptors that binds nonselectively to both beta 1 and beta 2 subtypes. The selective inhibition of 125I-labeled pindolol binding with specific antagonists of beta 1 and beta 2 receptors allowed the visualization of beta-adrenergic receptor subtypes. High levels of beta 1 receptors were observed in the cingulate cortex, layers I and II of the cerebral cortex, the hippocampus, the Islands of Calleja, and the gelatinosus, mediodorsal, and ventral nuclei of the thalamus. High levels of beta 2 receptors were found in the molecular layer of the cerebellum, over pia mater, and in the central, paraventricular, and caudal lateral posterior thalamic nuclei. Approximately equal levels of beta 1 and beta 2 receptors occurred in the substantia nigra, the olfactory tubercle, layer IV of the cerebral cortex, the medial preoptic nucleus, and all nuclei of the medulla. The pronounced differences in the ratio of beta 1 to beta 2 receptors among brain regions suggests that the subtypes of beta-adrenergic receptors may play different roles in neuronal function.
Mitochondrial gene flow.
Authors: Takahata N , Slatkin M
Published: May 2006

To account for the transmission of mitochondrial DNA between conspecific species Drosophila pseudoobscura and D. persimilis in sympatry reported by J.R. Powell [Powell, J.R. (1983) Proc. Natl. Acad. Sci. USA 80, 492-495], a simple model of gene flow and selection in infinite populations is analyzed. The model assumes two alleles at each of two loci, one of which is coded by an autosome and the other by mitochondrial DNA. Viability selection is presumed to be underdominant--i.e., heterozygous inferiority to the homozygotes--at an autosomal locus, and neutral or deleterious at a mitochondrial locus, with the combined action being multiplicative. Extremely strong selection against heterozygotes may prevent the transmission of mitochondrial DNA between two species, but otherwise the transmission can easily occur over species boundaries. The rate of approach to equilibrium is determined by the level of gene flow and is not affected much by selection against an autosomal locus. The divergence of the nuclear genomes of the two species is reexamined. Based on published data on enzyme loci, we conclude that there has been mitochondrial gene flow between these species for a long enough time that several nuclear loci examined could diverge because of accumulation of neutral mutations.
Neuronal growth cones: specific interactions mediated by filopodial insertion and induction of coated vesicles.
Authors: Bastiani M J , Goodman C S
Published: May 2006

We are interested in the factors that guide individual neuronal growth cones during embryonic development. Here we report on the discovery of a highly specific interaction between developing growth cones in the grasshopper embryo as revealed by transmission electron microscope serial-section reconstructions. Numerous filopodia from an identified growth cone (MP1) insert deep within another identified growth cone (pCC), inducing the formation of coated pits and vesicles. This interaction is highly specific, since filopodia from other nearby growth cones that contact the surface of the two interacting neurons neither penetrate them nor induce coated vesicles. These specific filopodial interactions may play an important role in the subsequent development of these neurons.
Corticotropin-releasing factor-immunoreactive neurons of the paraventricular nucleus become vasopressin positive after adrenalectomy.
Authors: Kiss J Z , Mezey E , Skirboll L
Published: May 2006

The immunoperoxidase technique was used to study the effect of adrenalectomy on vasopressin (VP) immunoreactivity in the hypothalamic paraventricular nucleus of rat. In control animals, relatively few VP-immunostained parvocellular neurons were found in addition to a large population of magnocellular VP neurons. Seven to 14 days after bilateral adrenalectomy, VP immunostaining increased markedly in specific subdivisions of the paraventricular nucleus. In contrast to normal animals, VP immunoreactivity was localized in a large number of parvocellular neurons. Colchicine treatment, on the other hand, did not significantly increase the number of VP-immunostained parvocellular neurons found in control rats. These observations suggest that adrenalectomy increases the number of VP-positive neurons and appears to increase the intensity of VP immunoreactivity specifically in parvocellular neurons. VP parvocellular neurons are confined to those paraventricular nucleus subdivisions that are known to project to the external zone of the median eminence. Moreover, their distribution pattern is very similar, if not identical, to that of the corticotropin-releasing factor (CRF) immunoreactive cells. Parvocellular neurons on adjacent thin sections could be stained for both CRF and VP. Thus, adrenalectomy seems to increase VP staining in CRF immunoreactive parvocellular neurons, which innervate the external zone of the median eminence.
Chiral probes for the handedness of DNA helices: enantiomers of tris(4,7-diphenylphenanthroline)ruthenium(II).
Authors: Barton J K , Basile L A , Danishefsky A , Alexandrescu A
Published: May 2006

The chiral complexes tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (RuDIP) are shown to be specific chemical probes with which to distinguish right- and left-handed DNA helices in solution. In spectrophotometric titrations of racemic RuDIP with both B-form calf thymus DNA and Z-form poly[d(G-C)], hypochromicity in the intense metal-to-ligand charge-transfer band is found and enhancement in luminescence is observed. The spectrophotometric assay of DNA binding to the well-resolved enantiomers of RuDIP provides a means to determine the helical conformation. Strong chiral specificity is seen in binding experiments with right-handed B-DNA and, on this basis, the absolute configurations are assigned. Although delta-RuDIP can bind by intercalation into the right-handed helix, steric constraints imposed by the helix asymmetry preclude completely binding by the lambda enantiomer. Both isomers, however, are found to bind equally to Z-DNA. Left-handed helices that are more similar structurally to B-DNA would be predicted to display a stereospecific preference for this lambda isomer.
A unique mechanism regulating gene expression: translational inhibition by a complementary RNA transcript (micRNA).
Authors: Mizuno T , Chou M Y , Inouye M
Published: May 2006

The expression of the genes for the major outer membrane proteins OmpF and OmpC are osmoregulated. The ompC locus was found to be transcribed bidirectionally under conditions of high osmolarity and a 174-base transcript encoded upstream of ompC was found to inhibit the OmpF production and to substantially reduce the amount of the ompF mRNA. This RNA [mRNA-interfering complementary RNA (micRNA)] has a long sequence that is complementary to the 5' end region of the ompF mRNA. We propose that the micRNA inhibits the translation of the ompF mRNA by hybridizing with it. This RNA interaction may cause premature termination of the transcription of the ompF gene or destabilization of the ompF mRNA or both.
Genomic sequencing.
Authors: Church G M , Gilbert W
Published: May 2006

Unique DNA sequences can be determined directly from mouse genomic DNA. A denaturing gel separates by size mixtures of unlabeled DNA fragments from complete restriction and partial chemical cleavages of the entire genome. These lanes of DNA are transferred and UV-crosslinked to nylon membranes. Hybridization with a short 32P-labeled single-stranded probe produces the image of a DNA sequence "ladder" extending from the 3' or 5' end of one restriction site in the genome. Numerous different sequences can be obtained from a single membrane by reprobing. Each band in these sequences represents 3 fg of DNA complementary to the probe. Sequence data from mouse immunoglobulin heavy chain genes from several cell types are presented. The genomic sequencing procedures are applicable to the analysis of genetic polymorphisms, DNA methylation at deoxycytidines, and nucleic acid-protein interactions at single nucleotide resolution.
On the mechanism of energy transduction in myosin subfragment 1.
Authors: Botts J , Takashi R , Torgerson P , Hozumi T , Muhlrad A , Mornet D , Morales M F
Published: May 2006

It is proposed that the myosin subfragment 1 moiety of the muscle contractile apparatus is a self-contained "engine" whose operational plan is based on the interactive nature of ATP (or degradation intermediate) binding and actin binding, made possible by an intersite communication system. It is suggested that the spatial information required for examining this engine can, at least provisionally, be derived from fluorescence resonance energy transfer measurements interpreted by the Förster equation and that the existence of an intersite communication system can be deduced from piece-wise detection of interacting pairs of points.
A mutagen-testing assay based on heterogeneity in diameter and integrated optical density of mammalian cell colonies.
Authors: Dairkee S H , Glaser D A
Published: May 2006

We investigated the effects of the well-known mutagenic agents ethyl methanesulfonate (EtMes), N-methyl-N-nitro-N-nitrosoguanidine (MNNG), and ICR-191 on colonies of the Chinese hamster ovary line CHO cultured on a semisolid substrate. These agents induced heterogeneity in diameter and integrated optical density of colonies as determined by computer-assisted photography and subsequent analysis of the images of the colonies. When CHO colonies were exposed to agents such as urethane that are not known to be mutagenic in mammalian systems or to activation-requiring mutagens such as cyclophosphamide, there was no noticeable effect on the distribution of colony diameter and volume. Similarly, nonmutagenic agents such as dimethyl sulfoxide (Me2SO) also did not induce heterogeneity in colony diameter and integrated optical density. Our observations recommend the use of agar-grown mammalian cell colonies for predictive testing of chemical mutagens and carcinogens in a simple, in vitro mammalian cell assay. This assay system, unlike other mammalian cell culture assays, allows detection and measurement of the simultaneous effects of chemical mutagens on several genetic and non-genetic targets and, thus, may emulate more closely the potential hazards of these agents in vivo.
Mice homozygous for chromosomal deletions at the albino locus region lack specific polypeptides in two-dimensional gels.
Authors: Baier L J , Hanash S M , Erickson R P
Published: May 2006

Radiation-induced chromosomal deletions involving the albino locus region of the mouse result, when homozygous, in abnormalities ranging from sterility to lethality at various stages of development. We have utilized two-dimensional electrophoresis to search for polypeptide alterations in livers from newborn mice homozygous for the c14CoS and c3H deletions and also from c3H/c6H compound heterozygote mice. Five-hundred polypeptide spots detectable in normal mouse liver gels were scored. Alterations involving five polypeptides were observed in the various overlapping deletions. A spot corresponding to a polypeptide with a 38,000 Mr was missing from mice homozygous for the short c14CoS and the longer overlapping c3H deletions. Another polypeptide with a 29,000 Mr was missing from c3H homozygotes and c3H/c6H heterozygotes. A third polypeptide with a 62,000 Mr was missing only from c3H homozygotes. Two additional polypeptides were markedly increased in amount in c14CoS and c3H homozygotes. The partial overlap between the three deletions analyzed allows provisional genetic mapping of previously unknown loci for three of the five electrophoretically identifiable polypeptides expressed in newborn mouse livers. The results obtained provide a basis for studying radiation-induced deletions with two-dimensional electrophoresis gels.
Identification, molecular cloning, and mutagenesis of Saccharomyces cerevisiae RNA polymerase genes.
Authors: Ingles C J , Himmelfarb H J , Shales M , Greenleaf A L , Friesen J D
Published: May 2006

Three different regions of Saccharomyces cerevisiae DNA were identified by using as hybridization probe a fragment of Drosophila melanogaster DNA that encodes an RNA polymerase II (EC 2.7.7.6) polypeptide. Two of these regions have been molecularly cloned. Each contains a sequence related not only to the D. melanogaster DNA fragment that was used as a probe in its isolation but also to the immediately adjacent DNA fragment of the D. melanogaster RNA polymerase II gene. The two cloned S. cerevisiae DNA sequences are each the template for single transcripts in vivo, one of 5.9 kilobases and the other of 4.6 kilobases. In vitro translation of hybrid-selected cellular RNA indicated that the former locus encodes a protein of Mr 220,000, equal in size to the largest polypeptide subunit of S. cerevisiae RNA polymerase II. Disruption of either gene by targeted integration of URA3+ DNA demonstrated that each is single-copy and essential in a haploid genome. We suggest that these S. cerevisiae loci are members of a family of related genes encoding the largest subunit polypeptides of RNA polymerases I, II, and III.
Antibodies of predetermined specificity against chemically synthesized peptides of human interleukin 2.
Authors: Altman A , Cardenas J M , Houghten R A , Dixon F J , Theofilopoulos A N
Published: May 2006

This communication describes the preparation of antibodies to human interleukin 2 (IL-2), using as immunogens synthetic peptides derived from the predicted amino acid sequence of IL-2. Rabbits and mice were immunized with protein carrier conjugates of eight chemically synthesized IL-2-derived peptides, each consisting of 13-15 amino acids. The immune antisera were screened in a solid-phase ELISA for reactivity to a native human IL-2. Antibodies to four of the eight peptides were found by a variety of biological and immuno-chemical criteria to react against human IL-2. Furthermore, an affinity-purified antibody to one of the IL-2 peptides (peptide 84) specifically stained the cytoplasm of phytohemagglutinin-stimulated human peripheral blood lymphocytes or T-leukemic cells (Jurkat). Antibodies to synthetic IL-2 peptides should serve as useful probes for studying this lymphokine and for developing quantitative assays for measuring its levels in biological fluids and its association with disease.
Antileukemic and immunosuppressive activity of 2-chloro-2'-deoxyadenosine.
Authors: Carson D A , Wasson D B , Beutler E
Published: May 2006

The adenosine deaminase-resistant purine deoxynucleoside 2-chloro-2'-deoxyadenosine (CdA) is markedly toxic in vitro to nondividing and proliferating normal human lymphocytes and to many leukemia cell specimens. The CdA is also effective against mouse L1210 leukemia in vivo. The present investigations have examined the pharmacology, chemotherapeutic activity, and toxicity of CdA in nine patients with advanced hematologic malignancies refractory to conventional therapy. When administered by continuous intravenous infusion, the deoxyadenosine analog was well tolerated. As monitored by radioimmunoassay, plasma CdA levels rose gradually during the infusions. The CdA was not deaminated significantly. In all patients with leukemia, the CdA lowered the blast count by at least 50%. In one patient with a T-cell leukemia-lymphoma, and in another patient with chronic myelogenous leukemia in blast crisis, the CdA infusion eliminated all detectable blasts from the blood and bone marrow. In a patient with a diffuse lymphoma complicated by severe autoimmune hemolytic anemia, CdA treatment quickly terminated the hemolytic process. Bone marrow suppression represented the dose-limiting toxicity, and was related to plasma CdA levels, cumulative drug dosage, and the rapid release of CdA that accompanied tumor cell lysis.