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Biomedical subjects

S Weiss

Publications and source records attributed to S Weiss.

At least 235 records · Page 13Linked to original sources
PubMed1995

Overexpression of active Syrian golden hamster prion protein PrPc as a glutathione S-transferase fusion in heterologous systems.

This article describes a procedure which permits for the first time the isolation of the prion protein PrPc from the Syrian golden hamster in heterologous systems. Using a glutathione S-transferase (GST) fusion approach, milligram amounts of stable, soluble, and homogeneous GST::PrPc protein were obtained in Escherichia coli and with baculovirus-infected insect cells. Authentic PrPc was released from the immobilized fusion protein by direct cleavage with thrombin. GST::PrPc expressed in these two expression systems and also authentic PrPc released by thrombin cleavage were recognized by a polyclonal antibody directed against amino acid 95 to 110 of the golden hamster PrPc protein. GST::PrPc was not detected by a monoclonal antibody recognizing the region encompassing amino acids 138 to 152 of the human prion protein. The fusion protein was sensitive to proteinase K digestion, demonstrating that the cellular rather than the proteinase K-resistant scrapie isoform was produced.

Animals↗
PubMed1995

Sources of alcohol and drug information among Israeli urban adolescents.

This article describes a study which investigated sources of alcohol and drug information among Israeli urban adolescents in the north of Israel during the winter of 1993. Data were obtained from a sample of 1,346 students (50.9% males, 49.1% females), who were asked to indicate the amount of information (none, little, much) they had received from ten sources about eight categories of drugs. Among the findings: television is the primary source of information for all drugs, except inhalants, for which newspapers/magazines are the main source. Newspapers/magazines are of secondary importance for the rest of the seven categories of drugs. Teenagers are less likely to receive information from physicians/nurses and relatives than from other sources. Information based on personal experience is prominent concerning alcohol, cigarettes, inhalants and hashish/marijuana, and it prevails more among males than among females (p < .01). Females use school teachers as a source of information in all drug categories more than males (p < .01). There are differences in using various information sources among grades and types of places of living. Information based on personal experience with alcohol is notably correlated with that with cigarettes, whereas information based on personal experience with opiates is correlated with that with stimulants, hallucinogens and hashish/marijuana (p < .001). The mean number of sources of information used by the respondents is the highest concerning alcohol and the lowest concerning depressants. Implications for prevention are discussed.

Adolescent↗
PubMed1995

Reasons for abstinence among Moslem, Druze, and Christian adolescents in Israel.

This article describes reasons for abstinence of 1,066 Israeli Arab (Moslem, Druze, and Christian) adolescents in the north of Israel in winter 1994. It analyzes the results by religious group, gender, and location. "Alcohol damages health" and "Do not like the taste/smell" are the most prevalent reasons for not drinking among Christians. "Alcohol damages health" and "Religion intolerant of alcohol use" are most important among Moslems and Druze. "Do not care for it" and "Have seen bad examples of what alcohol can do" are also prominent reasons among Arab respondents. Implications of results for prevention are included.

Adolescent↗
PubMed1995

BDNF enhances the differentiation but not the survival of CNS stem cell-derived neuronal precursors.

We have previously reported the isolation of an EGF-responsive precursor from the embryonic and adult mouse striatum. This precursor exhibits self renewal and the ability to produce a sphere of undifferentiated cells which can be induced to differentiate into neurons and glia. RT-PCR analysis of these spheres of undifferentiated cells revealed the expression of mRNA for the trkB neurotrophin receptor, both with and without the catalytic domain, and little or no expression of trkA or trkC. We examined the actions of BDNF on the fate of EGF-generated neural precursors. Ten days after a one-time exposure to BDNF, single EGF-generated spheres showed a twofold increase in neuron number and a marked enhancement in neurite outgrowth. Examination of neuronal nuclei with immunochemical probes for c-fos and bromodeoxyuridine revealed that the actions of BDNF were directly upon neuronal cells and did not involve division of neuronal precursors. The twofold increase in neuronal number due to BDNF, observed after 10 d in vitro, was significantly reduced after 21 d in vitro and was not apparent at 27 d in vitro. Quantitative analyses revealed that while repeated application of BDNF did not prevent the loss of neuron number over time, it did result in a significant increase in neurite numbers. Moreover, delayed addition of BDNF mimicked the increase in neuronal numbers seen when BDNF was present throughout. These BDNF actions did not appear to involve the enhancement of a novel neuronal phenotype, with all effects being due to increase in the numbers and neurite outgrowth of neurons that colocalize GABA and substance P. These findings suggest that BDNF markedly enhances the antigenic and morphologic differentiation of EGF-generated neuronal precursors. BDNF alone does not appear to act as a survival factor for neuronal precursors nor is it sufficient for preventing their death over time.

Animals↗
PubMed1995

Mechanisms in adverse reactions to food. The joints and muscles.

There are several reasons for considering the hypothesis that food hypersensitivity might relate to rheumatic diseases. Food can evoke immune responses. Food can cause immunologically mediated symptoms. Immunological mechanisms are important in the pathogenesis of rheumatic diseases. Antigens triggering rheumatic responses are unknown. Rheumatic diseases have been associated with foods in many reports.

Food Hypersensitivity↗
PubMed1995

Breast cancer and family history: levels of lipid-associated sialic acid in plasma and absent family history of breast cancer in women who have breast tumors.

BACKGROUND: Breast cancer has a strong genetic component, and at least two breast cancer genes exist. But these genes probably play little role in most breast cancers. Other factors, such as environmental estrogens and diet, may cause the genetic changes involved in the genesis of sporadic breast cancer. A method of observing genetic changes indirectly might be to measure tumor markers known to be associated with breast cancer. METHODS: We measured, by biochemical extraction and partition, lipid-associated sialic acid in plasma (LASA-P), a circulating tumor marker, in a group of 239 women with benign or malignant breast tumors. RESULTS: The concentration of LASA-P was elevated in women with both benign and malignant tumors and no family history of breast cancer (p = 0.046, one-way ANOVA). Because LASA-P levels rise with age and number of pregnancies, we analyzed our data using multiple linear regression. Benign versus malignant character of the tumor, family history of breast cancer, number of pregnancies, and age were the independent variables. Family history of breast cancer had a significant effect on LASA-P levels (p = 0.0146) independent of the effects of age (p = 0.011), number of pregnancies (0.012), and whether the tumor was benign or malignant (p = 0.31). CONCLUSIONS: We hypothesize that elevated LASA-P in women with breast tumors and no family history of breast cancer is a result of the genetic changes occurring in nonfamilial breast cancer. These genetic changes, possibly related to environmental estrogens or other environmental factors, are distinct from the changes due to mutations of BRCA1 or other familial breast cancer genes. Moreover, the elevation of LASA-P suggests that the surface membranes of breast cancer may differ in composition. Further study may lead to exact characterization of the genetic and cell membrane changes associated with familial and nonfamilial breast tumors, and perhaps to better methods of breast cancer prevention and treatment.

Adolescent↗
PubMed1994

T cell epitope analysis with peptides simultaneously synthesized on cellulose membranes: fine mapping of two DQ dependent epitopes.

Several MHC class II restricted, CD4+ human T cell clones from three donors were induced with soluble matrix protein of influenza virus. The epitopes recognized by these clones were mapped using a complete set of overlapping 15-mer peptides synthesized with the newly developed SPOT method which allows the simple simultaneous synthesis of numerous peptides on cellulose membranes. Fine analysis of two clones by truncation of the stimulatory peptide by single subsequent amino acids from either the NH2- or the COOH-terminus revealed the minimal stimulatory determinants of two DQ dependent T cell epitopes.

Amino Acid Sequence↗
PubMed1994

Dietary magnesium, lung function, wheezing, and airway hyperreactivity in a random adult population sample.

Magnesium is involved in a wide range of biological activities, including some that may protect against the development of asthma and chronic airflow obstruction. We tested the hypothesis that high dietary magnesium intake is associated with better lung function, and a reduced risk of airway hyper-reactivity and wheezing in a random sample of adults. In 2633 adults aged 18-70 sampled from the electoral register of an administrative area of Nottingham, UK, we measured dietary magnesium intake by semiquantitative food-frequency questionnaire, lung function as the 1-sec forced expiratory volume (FEV1), and atopy as the mean skin-prick test response to three common environmental allergens. We measured airway reactivity to methacholine in 2415 individuals, defining hyper-reactivity as a 20% fall in FEV1 after a cumulative dose of 12.25 mumol or less. Mean (SD) daily intake of magnesium was 380 (114) mg/day. After adjusting for age, sex, and height, and for the effects of atopy and smoking, a 100 mg/day higher magnesium intake was associated with a 27.7 (95% CI, 11.9-43.5) mL higher FEV1, and a reduction in the relative odds of hyper-reactivity by a ratio of 0.82 (0.72-0.93). The same incremental difference in magnesium intake was also associated with a reduction in the odds of self-reported wheeze within the past 12 months, adjusted for age, sex, smoking, atopy, and kilojoule intake, by a ratio of 0.85 (0.76-0.95). Dietary magnesium intake is independently related to lung function and the occurrence of airway hyper-reactivity and self-reported wheezing in the general population. Low magnesium intake may therefore be involved in the aetiology of asthma and chronic obstructive airways disease.

Adult↗
PubMed1994

Naive idiotype-specific CD4+ T cells and immunosurveillance of B-cell tumors.

The immunosurveillance hypothesis suggests that lymphocytes can recognize tumor-specific antigens expressed by transformed cells and initiate their elimination. Immunosurveillance implies that lymphocytes of naive phenotype can home to a tumor site and become activated by tumor-specific antigens. In this study, we have employed T-cell receptor transgenic mice as a source of naive, tumor-specific T cells. The transgenic, CD4+ T cells recognize a 91- to 101-residue fragment of the lambda 2(315) immunoglobulin light chain presented by I-Ed class II molecules. Such naive, idiotype-specific, CD4+ T cells protected against tumor development of a class II negative plasmacytoma (MOPC315) and a class II positive B lymphoma (F9), which both secrete lambda 2(315) immunoglobulin. Adoptive transfer experiments demonstrated that 2 x 10(6) lymph node cells were sufficient for protection against MOPC315. Depletion of T-cell subsets indicated that transgenic CD4+ cells were indispensable for tumor resistance. However, an additional role of CD8+ T cells is not ruled out. In contrast to the resistance against the secreting MOPC315 and F9 cells, transgenic mice were not protected against B lymphoma cells (F67), which do not secrete lambda 2(315) but express a truncated lambda 2(315) chain intracellularly. The results suggest that lambda 2(315) is processed and presented by host antigen-presenting cells, which in turn activate naive, idiotype-specific T cells.

Animals↗
PubMed1994

State of the cart.

Food on wheels: it's here, there and everywhere. But while some operations rev up cart expansion plans, others have shifted into low gear. Here's an update on that '90s phenomenon: mobile merchandising.

Entrepreneurship↗
PubMed1994

Genetic mapping of the gene for Usher syndrome: linkage analysis in a large Samaritan kindred.

Usher syndrome is a group of autosomal recessive disorders associated with congenital sensorineural deafness and progressive visual loss due to retinitis pigmentosa. Sixteen members of the small inbred Samaritan isolate with autosomal recessive deafness were studied in 10 related sibships. DNA samples from 59 individuals including parents and affected and nonaffected sibs were typed for markers on chromosomes 1q and 11q for which linkage has recently been established for Usher syndrome types II and I. Statistically significant linkage was observed with four markers on 11q (D11S533, D11S527, OMP, and INT2) with a maximum six-point location score of 11.61 at the D11S533 locus. Analysis of haplotypes supports the notion that the mutation arose only once in an ancestral chromosome carrying a specific haplotype. The availability of markers closely linked to the disease locus allows indirect genotype analysis and identifies all carriers of the gene within the community. Furthermore, the detection of complete linkage disequilibrium between the D11S533 marker and the Usher gene suggests that these loci are either identical or adjacent and narrows the critical region to which physical mapping efforts are currently directed.

Chromosome Mapping↗
PubMed1994

Tight nucleotide binding sites and ATPase activities of the Rhodospirillum rubrum RrF1-ATPase as compared to spinach chloroplast CF1-ATPase.

Solubilized Rhodospirillum rubrum RrF1-ATPase, depleted of loosely bound nucleotides, retains 2.6 mol of tightly bound ATP and ADP/mol of enzyme. Incubation of the depleted RrF1 with Mg(2+)-ATP or Mg(2+)-AMP-PNP, followed by passage through two successive Sephadex centrifuge columns, results in retention of a maximal number of 4 mol of tightly bound nucleotides/mol of RrF1. They include 1.5 mol of nonexchangeable ATP, whereas all tightly bound ADP is fully exchangeable. A similar retention of only four out of the six nucleotide binding sites present on CF1 has been observed after its passage through one or two centrifuge columns. These results indicate that the photosynthetic, unlike the respiratory, F1-ATPases have faster koff constants for two of the Mg-dependent nucleotide binding sites. This could be the reason for the tenfold lower Mg2+ than Ca(2+)-ATPase activity observed with native RrF1, as with epsilon-depleted, activated CF1. An almost complete conversion of both RrF1 and CF1 from Ca(2+)- to Mg(2+)-dependent ATPases is obtained upon addition of octylglucoside, at concentrations below its CMC, to the ATPase assay medium. Thus, octylglucoside seems to affect directly the RrF1 and CF1 divalent cation binding site(s), in addition to its proposed role in relieving their inhibition by free Mg2+ ions. The RrF1-ATPase activity is 30-fold more sensitive than CF1 to efrapeptin, and completely resistant to either inhibition or stimulation by the CF1 effector, tentoxin. Octylglucoside decreases the inhibition by efrapeptin and tentoxin, but exposes on CF1 a low-affinity, stimulatory site for tentoxin.

Adenine Nucleotides↗
PubMed1994

Neural stem cells in the adult mammalian forebrain: a relatively quiescent subpopulation of subependymal cells.

Dissection of the subependyma from the lateral ventricle of the adult mouse forebrain is necessary and sufficient for the in vitro formation of clonally derived spheres of cells that exhibit stem cell properties such as self-maintenance and the generation of a large number of progeny comprising the major cell types found in the central nervous system. Killing the constitutively proliferating cells of the subependyma in vivo has no effect on the number of stem cells isolated in vitro and induces a complete repopulation of the subependyma in vivo by relatively quiescent stem cells found within the subependyma. Depleting the relatively quiescent cell population within the subependyma in vivo results in a corresponding decrease in spheres formed in vitro and in the final number of constitutively proliferating cells in vivo, suggesting that a relatively quiescent subependymal cell is the in vivo source of neural stem cells.

Animals↗
PubMed1994

Synthesis of 2-[18F]fluoro-2-deoxy-L-glucose and positron emission tomography studies in monkeys.

2-[18F]Fluoro-2-deoxy-L-glucose was synthesized from its trifluoromethanesulfonyl precursor. The precursor was prepared by selective acetylation and triflation of L-mannose. L-Mannose was first treated with acetic anhydride in the presence of a catalytic amount of perchloric acid and then reacted with phosphorus tribromide followed by aqueous sodium acetate to produce pure 1,3,4,6-tetra-O-acetyl-a-L-mannopyranose in 32% yield. This compound was treated with trifluoromethanesulfonic anhydride and pyridine in methylene chloride to form 1,3,4,6-tetra-O-acetyl-O-tritrifluoromethanesulfonyl-a-L-mannopyra nose in 77% yield. Nucleophilic substitution of the triflate with 18F-in the presence of Kryptofix 2,2,2 followed by acid hydrolysis produced 2-[18F]fluoro-2-deoxy-L-glucose with a radiochemical yield of 20-30% (EOS) within 90 min. Biodistribution studies in rats and PET imaging in Rhesus monkeys demonstrated that this sugar analog distributes in the extracellular space of most organs but is excluded from the CNS.

Animals↗