Suicidal process,suicidal communication and psychosocial situation of young suicide attempters in a rural Vietnamese community

The study aimed to explore the suicidal process, suicidal communication and psychosocial situation of young suicide attempters in a rural community in Hanoi, Vietnam. Semi-structured interviews were conducted, in a community setting, with 19 suicide attempters aged 15-24 who had been consecutively hospitalized in an intensive care unit. In 12 of 19 cases, the first pressing, distinct and constant suicidal thoughts appeared less than one day before the suicide attempt in question. However, distress and mild, fleeting suicidal thoughts had been present up to six months before the suicide attempt in 16 cases. Five respondents had a suicide plan one to three days before attempting suicide. Altogether, 13 engaged in some form of suicidal communication before their attempt. This communication was, however, difficult for outsiders to interpret. Twelve of the respondents were victims of regular physical abuse and 16 had suffered psychological violence for at least one year before attempting suicide. Eighteen of the respondents used pesticides or raticides in their suicide attempts. None sought advice or consultation in the community despite long-standing psychosocial problems. The strategy of reducing the availability of suicide means (e.g., pesticides or raticides) in Asian countries should be complemented with a long-term suicide-preventive strategy that targets school dropouts and domestic violence, and promotes coping abilities and communication about psychological and social problems as well as recognition of signs of distress and suicidal communication.     

Isolation and characterisation of a soluble active fragment of hydrogenase isoenzyme 2 from the membranes of anaerobically grown Escherichia coli

An active tryptic fragment of membrane-bound hydrogenase isoenzyme 2 from anaerobically grown Escherichia coli has been purified. The soluble enzyme derivative was released from the membrane fraction by trypsin cleavage. The purification procedure involved ion-exchange, hydroxyapatite and gel permeation chromatography. The enzyme derivative was purified 100-fold from the membrane fraction and the specific activity of the final preparation was 320 mumol benzyl viologen reduced min-1 mg protein-1 (H2:benzyl viologen oxidoreductase). The native enzyme derivative had an Mr of 180,000 and was composed of equimolar amounts of polypeptides of Mr 61,000 and 30,000. It possessed 12.5 mol Fe, 12.8 mol acid-labile S2- and 3.1 mol Ni/180,000 g enzyme. Antibodies were raised to the purified preparation which cross-reacted with hydrogenase isoenzyme 2 but not with isoenzyme 1 in detergent-dispersed preparations. Western immunoblot analysis revealed that isoenzyme 2 which had not been exposed to trypsin contained cross-reacting polypeptides of Mr 61,000 and 35,000. Trypsin treatment of the membrane-bound enzyme to form the soluble derivative of isoenzyme 2, therefore, cleaves a polypeptide of Mr 35,000 to produce the 30,000-Mr fragment. Trypsin treatment of the detergent-dispersed isoenzyme 2 produces the same fragmentation of the enzyme. Neither of the subunits of the enzyme revealed any immunological identity with those of hydrogenase isoenzyme 1.     

Extracellular adenosine nucleotides stimulate protein kinase C activity and human neutrophil activation

We studied the effect of adenosine nucleotides on several aspects of the functional activation of human peripheral blood polymorphonuclear leukocytes (PMN). Radiolabeled ATP bound to PMN in a manner suggesting the existence of specific binding sites because: 1) binding was reversed (92 +/- 6%) by 100-fold excess concentrations of unlabeled ATP but minimally by either ADP (43 +/- 12%) or GTP (37 +/- 8%); and 2) binding saturation was achieved (i.e., specific binding did not increase) above 250 microM ATP. Binding studies revealed that significant ATP hydrolysis occurred, even at low temperatures and in the presence of phosphatase inhibitors. Adenosine nucleotides activated signal transduction mechanisms in PMN because: 1) 1 to 100 microM ATP and 5'-adenylylimidodiphosphate (AMP-PNP) stimulated increased production of 1,2-diacylglycerols; 2) ATP (0.5 to 500 microM) and ADP (0.1 to 10 mM) induced increased insoluble protein kinase (PKC) activity in a dose-dependent manner when used at concentrations greater than 50 microM; 3) ATP (greater than or equal to 50 microM) induced a shift in the solubility of phorbol receptors from mostly soluble (89% in untreated cells) to mostly insoluble (68%), whereas ADP, GTP, and GDP were effective at higher concentrations; and 4) greater than or equal to 50 microM ATP stimulated increased phosphorylation of endogenous PMN proteins. AMP-PNP induced PKC activity and phosphoprotein changes that were qualitatively similar to those observed when PMN were treated with ATP, suggesting that extracellular ATP hydrolysis is not required for signal transduction to activate PKC. Functionally, ATP stimulated the secretion of specific (but not azurophil) granules because vitamin B12-binding protein and low levels of lysozyme, but not beta-glucuronidase, were released; qualitatively similar results were obtained by using AMP-PNP. These results suggest that certain adenosine nucleotides employed at physiologically relevant concentrations stimulate increased 1,2-diacylglycerol production, PKC activity, granule secretion, and endogenous phosphoprotein formation in a manner that is independent of extracellular ATP hydrolysis.     

A set of surface proteins common to the circulating human platelet and lymphocyte (Short Communication)

The surface proteins of the circulating human platelet and lymphocyte were labelled by using the lactoperoxidase iodination method. Polyacrylamide-gel electrophoresis showed that four corresponding labelled proteins are found on the surface of each cell type. The most intensely labelled protein contains little or no carbohydrate, but the remaining labelled proteins are all glycoproteins. The major labelled band from each cell was isolated and comparative peptide ;maps' showed that the two proteins are closely similar. The surface proteins of the lymphocyte and platelet are distinct from those on the erythrocyte, the remaining major type of circulating cell.     

Biochemical characterization and electron-transfer reactions of sym1, a Rhodobacter capsulatus reaction center symmetry mutant which affects the initial electron donor.

A 51 bp section of the Rhodobacter capsulatus photosynthetic reaction center M subunit gene (nucleotides M562-M612 of the pufM structural sequence) encoding amino acids M187-M203 was replaced by the homologous region of the L subunit gene. This resulted in the symmetrization of much of the amino acid environment of the reaction center initial electron donor, P. This is the first in a series of large-scale symmetry mutations and is referred to as sym1. The sym1 mutant was able to grow photosynthetically, indicating that reaction center function was largely intact. Isolated reaction centers showed an approximately 10-nm blue shift in the QY band of P. The standard free energy change between P* and P+BphA- determined from analysis of the long-lived fluorescence from quinone-reduced reaction centers decreased from about -120 meV in the wild-type to about -75 meV in the sym1 mutant. A 65-70% quantum yield of electron transfer from P* to P+QA- was observed, most of the yield loss occurring between P* and P+BphA-. The decay of the stimulated emission from P* was about 3-fold slower in this mutant than in the wild-type. Time-resolved spectral analysis of the charge-separated intermediates formed in sym1 reaction centers indicated that the major product was P+BphA-. A model-dependent analysis of the observed rates and electron-transfer yields gave the following microscopic rate constants for sym1 reaction centers (wild-type values under the same conditions are given in parentheses): [formula: see text] Analysis of the sym1 mutant, mutants near P made by other groups, and interspecies variation of amino acids in the vicinity of P suggests that the protein asymmetry in the environment of the initial electron donor is important for optimizing the rate and yield of electron transfer, but is not strictly required for overall reaction center function.     

NF-kappa B sites function as positive regulators of expression of the translocated c-myc allele in Burkitt''s lymphoma.

An in vivo footprint over a potential NF-kappa B site in the first exon of the c-myc gene has been identified on the translocated allele in the Ramos Burkitt's lymphoma cell line. The potential NF-kappa B site in the 5' flanking sequence of c-myc was found to be occupied on the translocated allele in the Raji Burkitt's cell line. Electrophoretic mobility shift assays with each of these sequences demonstrated complexes with mobilities identical to those of the NF-kappa B site from the kappa light-chain gene. A supershift was obtained with anti-p50 antibody with the exon site. The upstream-site shift complex disappeared with the addition of anti-p50 antibody. Binding of NF-kappa B proteins to the c-myc exon and upstream sites was demonstrated by induction of binding upon differentiation of pre-B 70Z/3 cells to B cells. UV cross-linking experiments revealed that a protein with a molecular mass of 50 kDa bound to the exon and upstream sites. Transfection experiments with Raji cells demonstrated that both sites functioned as positive regulatory regions, with a drop in activity level when either site was mutated. Access to these sites is blocked in the silent normal c-myc allele in Burkitt's lymphoma cells, while Rel family proteins bind to these sites in the translocated allele. We conclude that the two NF-kappa B sites function as positive regulatory regions for the translocated c-myc gene in Burkitt's lymphoma.