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Biomedical subjects

D Alexander

Publications and source records attributed to D Alexander.

At least 37 records · Page 2Linked to original sources
PubMed1996

The health effects of earthquakes in the mid-1990s.

This paper gives an overview of the global pattern of casualties in earthquakes which occurred during the 30-month period from 1 September 1993 to 29 February 1996. It also describes some of the behavioural and logistical regularities associated with mortality and morbidity in these events. Of 83 earthquakes studied, there were casualties in 49. Lethal earthquakes occurred in rapid succession in Indonesia, China, Colombia and Iran. In the events studied, a disproportionate number of deaths and injuries occurred during the first six hours of the day and in earthquakes with magnitudes between 6.5 and 7.4. Ratios of death to injury varied markedly (though with some averages close to 1:3), as did the nature and causes of mortality and morbidity and the proportion of serious to slight injuries. As expected on the basis of previous knowledge, few problems were caused by post-earthquake illness and disease. Also, as expected, building collapse was the principal source of casualties: tsunamis, landslides, debris flows and bridge collapses were the main secondary causes. In addition, new findings are presented on the temporal sequence of casualty estimates after seismic disaster. In synthesis, though mortality in earthquakes may have been low in relation to long-term averages, the interval of time studied was probably typical of other periods in which seismic catastrophes were relatively limited in scope.

Building Codes↗
PubMed1995

In situ isolation of mRNA from individual plant cells: creation of cell-specific cDNA libraries.

A method for isolating and cloning mRNA populations from individual cells in living, intact plant tissues is described. The contents of individual cells were aspirated into micropipette tips filled with RNA extraction buffer. The mRNA from these cells was purified by binding to oligo(dT)-linked magnetic beads and amplified on the beads using reverse transcription and PCR. The cell-specific nature of the isolated mRNA was verified by creating cDNA libraries from individual tomato leaf epidermal and guard cell mRNA preparations. In testing the reproducibility of the method, we discovered an inherent limitation of PCR amplification from small amounts of any complex template. This phenomenon, which we have termed the "Monte Carlo" effect, is created by small and random differences in amplification efficiency between individual templates in an amplifying cDNA population. The Monte Carlo effect is dependent upon template concentration: the lower the abundance of any template, the less likely its true abundance will be reflected in the amplified library. Quantitative assessment of the Monte Carlo effect revealed that only rare mRNAs (< or = 0.04% of polyadenylylated mRNA) exhibited significant variation in amplification at the single-cell level. The cDNA cloning approach we describe should be useful for a broad range of cell-specific biological applications.

Base Sequence↗
PubMed1995

Antigenic heterogeneity of avian paramyxoviruses of serotype 2 ("Yucaipa-like") isolated from domestic and wild birds in Israel.

Thirty-three viruses of PMV-2 serotype isolated in Israel from domestic and wild birds during epizooty of a respiratory disease in 1979-1981 were studied comprehensively in comparison with a set of reference PMV-2 viruses using cross reaction hemagglutination inhibition tests, elution-hemagglutination pattern and pattern of migration of viral proteins in polyacrylamide gel electrophoresis. The results demonstrated considerable heterogeneity amongst the local isolates by the above three criteria which were not correlated with each other. There was no significant correlation between the differences found and chronology of isolation of the viruses. The results indicated that there may have been simultaneous co-circulation of different PMV-2 strains in the local avian reservoir at the beginning of the epizootic rather than temporal accumulation of variants as a result of antigenic drift of an "ancestor" virus which caused the initial infection.

Animals↗
PubMed1995

Strike-through contamination in saturated sterile dressings: a clinical analysis.

This multisite study examined the risk of strike-through contamination of 4" x 4" gauze sponges using a shortcut method of saturating sterile sponges directly on their wrappers. Sterile gauze sponges were saturated directly on their wrappers on hospital over-bed tables of postoperative general surgical patients. Cultures were taken at 0.5, 1, 3, and 5 minutes after saturation to ascertain whether strike-through contamination occurred. Saturated sponges showed significant microorganism growth when compared to expected zero microorganisms at all sampling times following saturation. Although microorganisms identified in strike-through contamination were not microbiologically or pathogenically threatening, the basic principle of asepsis was violated. There was no significant difference in strike-through contamination between sponges saturated on coated wrappers and sponges saturated on uncoated wrappers. Clinicians should be aware that coated wrappers do not provide a moisture-proof barrier against strike-through contamination. The findings suggest the shortcut method should not be used for saturating sponges.

Asepsis↗
PubMed1995

Ventilatory muscle strength and endurance in myasthenia gravis.

Patients with generalized myasthenia gravis (MG) often have associated ventilatory muscle involvement. It is not known whether patients with isolated ocular muscle involvement have identifiable involvement of their ventilatory muscles. Most studies have assessed muscle involvement by measuring muscle strength; however, we hypothesized that measures of ventilatory muscle endurance may be more sensitive tests of ventilatory muscle involvement in myasthenia gravis. We studied 17 patients with myasthenia gravis (four with ocular involvement alone and 13 with varying degrees of generalized myasthenia gravis). Spirometry, ventilatory muscle strength (maximum inspiratory and expiratory pressures (MIP and MEP)) and endurance (2 min incremental threshold loading test) were measured before and 20 min after i.m. neostigmine. We compared the results with those of 10 normal controls. We found no difference between patients with isolated ocular involvement and controls. Ocular myasthenia gravis patients did not improve after neostigmine. The patients with generalized myasthenia gravis had reduced baseline ventilatory muscle strength (MIP 67 cmH2O (70% of predicted), MEP 86 cmH2O (50% of pred) and endurance (mean maximal load achieved = 246 g, mean pressure at highest load (P) = 19.4 cmH2O) compared with controls. After neostigmine, there was a significant increase in MIP in patients with generalized myasthenia gravis and a trend towards an increased MEP. As a group, the patients with generalized myasthenia gravis did not demonstrate a change in their ventilatory muscle endurance after neostigmine; however, there was considerable interpatient variability in response. We conclude that patients with isolated ocular MG have normal ventilatory muscle strength when tested conventionally.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

FK506 and cyclosporin A each inhibit antigen-specific signaling in the T cell line 171 in the absence of a calcium signal.

Antigen-specific signal transduction leading to IL2 induction and secretion in the T cell line 171 is augmented by association of p56lck with CD4. Although no change in cytoplasmic calcium level ([Ca2+]i) was detectable during antigen-specific signal transduction of 171-CD4+ cells, IL2 induction was inhibited by FK506 and CsA. Since these drugs are thought to act selectively by inhibiting calcineurin, a calcium-calmodulin-dependent protein phosphatase associated with activation of the IL2 promoter, we considered the possibility that calcineurin is constitutively active in 171 cells. However, we found no evidence for this because PMA failed to supplement any putatively active calcineurin to induce IL2 secretion. We suggest that IL2 secretion induced by antigen presentation to TCR/CD4/p56lck requires an FK506 and cyclosporin A-sensitive step which may be independent of calcium signaling. Rapamycin did not inhibit IL2 secretion induced by TCR/CD4/p56lck, emphasizing the specific action of FK506 and cyclosporin A.

Amino Acid Sequence↗
PubMed1994

The CD45 tyrosine phosphatase regulates specific pools of antigen receptor-associated p59fyn and CD4-associated p56lck tyrosine in human T-cells.

A newly isolated T-cell line (CB1) derived from a T-acute lymphoblastic leukaemia (T-ALL) patient contained cells (40% of total) which did not express the CD45 phosphotyrosine phosphatase. The cells were sorted into CD45- and CD45+ populations and shown to be clonal in origin. T-cell receptor (TCR) cross-linking or coligation of the TCR with its CD4/CD8 co-receptors induced tyrosine phosphorylation and calcium signals in CD45+ but not in CD45- cells. Unexpectedly, whole cell p56lck and p59fyn tyrosine kinase activities were not reduced in CD45- compared to CD45+ cells. A novel technique was therefore developed to isolated specific pools of aggregated receptors expressed at the cell surface, together with their associated tyrosine kinases. Using this technique it was shown that cell surface CD4-p56lck kinase activity was 78% lower in CD45- than in CD45+ cells. Phosphorylation of TCR zeta- and gamma-chains occurred in TCR immunocomplexes from CD45+ but not CD45- cells, despite comparable levels of p59fyn and TCR proteins. Furthermore, TCR-associated tyrosine kinase activity towards an exogenous substrate was 84% lower in CD45- than in CD45+ cells. Addition of recombinant p59fyn to TCR immunocomplexes isolated from CD45-cells restored the phosphorylation of the TCR zeta- and gamma-chains. Our results demonstrate that CD45 selectively regulates the pools of p59fyn and p56lck kinases which are associated with the TCR and CD4 at the cell surface. Activation by CD45 of these receptor-associated kinase pools correlates with the ability of the TCR and its coreceptors to couple to intracellular signalling pathways.

CD4 Antigens↗
PubMed1994

Densities of Vibrio vulnificus in the intestines of fish from the U.S. Gulf Coast.

Densities of Vibrio vulnificus in the intestinal contents of various finfish, oysters, and crabs and in sediment and waters of the U.S. Gulf Coast were determined by the most probable number procedure. Species were identified by enzyme immunoassay. During the winter, densities of V. vulnificus were low, and the organism was isolated more frequently from sheepshead fish than from sediment and seawater. From April to October, V. vulnificus densities were considerably higher (2 to 5 logs) in estuarine fish than in surrounding water, sediment, or nearby oysters and crustacea. Highest densities were found in the intestinal contents of certain bottom-feeding fish (10(8)/100 g), particularly those that consume mollusks and crustaceans. Densities of V. vulnificus in fish that feed primarily on plankton and other finfish were similar to those in oysters, sediment, and crabs (10(5)/100 g). V. vulnificus was found infrequently in offshore fish. The presence of high densities of V. vulnificus in the intestines of common estuarine fish may have both ecological (growth and transport) and public health (food and wound infections) implications.

Alabama↗
PubMed1994

A novel inhibitor of cyclin-Cdk activity detected in transforming growth factor beta-arrested epithelial cells.

Transforming growth factor beta (TGF-beta) is a potent inhibitor of epithelial cell growth. Cyclins E and A in association with Cdk2 have been shown to play a role in the G1-to-S phase transition in mammalian cells. We have studied the effects of TGF-beta-mediated growth arrest on G1/S cyclins E and A. Inhibition of cyclin A-associated kinase by TGF-beta is primarily due to a decrease in cyclin A mRNA and protein. By contrast, while TGF-beta inhibits accumulation of cyclin E mRNA, the reduction in cyclin E protein is minimal. Instead, we find that the activation of cyclin E-associated kinase that normally accompanies the G1-to-S phase transition is inhibited. A novel inhibitor of cyclin-Cdk complexes was detected in TGF-beta-treated cell lysates. Inhibition is mediated by a heat-stable protein that targets both Cdk2 and Cdc2 kinases. In G0-arrested cells, a similar inhibitor of Cdk2 kinase was detected. These data suggest the existence of an inhibitor of cyclin-dependent kinases induced under different conditions to mediate antiproliferative responses.

Animals↗
PubMed1994

Screening alcohol abuse potential among Army reservists with the Short Michigan Alcoholism Screening Test.

The Short Michigan Alcoholism Screening Test was psychometrically useful in screening a sample of 560 reservists from a midwest general hospital unit. The most conservative estimate of alcohol abuse potential was 11.3%, with possibly 6.6% having symptoms of alcohol dependence. Comparisons with active duty military, Army, and civilian samples suggest that prevalence of abuse in the Reserve sample is similar to that of the combined military, but lower than that of the Army. Future research and policy choices are highlighted.

Alcoholism↗
PubMed1994

Nutrient intake and haematological status of vegetarians and age-sex matched omnivores.

OBJECTIVE: The study was designed to investigate the nutritional intake and haematological status of adult vegetarians. DESIGN: Cross-sectional comparison of vegetarians and age/sex-matched omnivores. SETTING: Free-living community subjects. SUBJECTS: Fifty vegetarians were recruited by local advertisement. Each vegetarian selected their own age/sex-matched 'friend' control. OUTCOME MEASURES: Each subject completed a 12 day dietary record. Haemoglobin, red cell indices, and serum ferritin, B12 and folate were measured. RESULTS: Protein, saturated fat and vitamin D intake were significantly lower in the vegetarians, particularly in the vegans. Dietary fibre was higher in the vegetarians, and intake of calcium and zinc was similar. Mean (SD) iron intake in the vegetarians and vegans of 16.8 (4.8) mg/day was significantly greater than that of the omnivores: 14.6 (4.3) mg/day (P = 0.02). All the iron consumed by the vegetarians was non-haem; for the omnivores 10% was haem iron. Serum ferritin concentrations were significantly lower in male vegetarians than omnivores; mean (SD): 36.6 (36.0) and 105.4 (78.7) ng/ml, respectively, P < 0.01; and significantly more had values below 12 ng/ml (P < 0.001), despite having higher iron intakes which exceeded the Recommended Nutrient Intake (RNI). Female vegetarians also had lower ferritin concentrations than omnivores; mean (SD) 13.6 (7.5) compared to 33.6 (54.3) ng/ml, P < 0.01, but similar numbers of women had values below 12 ng/ml (42% and 39%). The vegans all had B12 intakes below the RNI; and 35% of the long-term vegetarians and vegans had serum vitamin B12 concentrations below the reference range. CONCLUSION: Although the vegetarians had diets nearer to the recommended diet with a lower fat and salt content, a significant number need advice to improve their haematological status. Recommended intakes of iron may also need to be higher for vegetarians, particularly men.

Adult↗