The toxicity of selenium in experimental freshwater ponds.
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Biomedical subjects
Publications and source records attributed to M Crane.
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In order to describe the British experience of Wegener's granulomatosis Hospital Activity Analysis was used to collect cases diagnosed in England, Wales and Scotland between 1975 and 1985. Where possible clinical details, histological material and chest radiographs were obtained. Two hundred and sixty five patients were considered to have Wegener's granulomatosis. In 109 a single pathologist confirmed the diagnosis by finding both granulomas and vasculitis in biopsy material. The diagnosis was made on clinical grounds or clinical grounds together with histological diagnosis in the local hospital in 156 patients. Wegener's granulomatosis was confined to the lung or upper respiratory tract in 22 per cent of patients and renal disease occurred in 58 per cent. Laboratory tests showed a pattern of mild anaemia, polymorph leucocytosis, eosinophilia and an elevated ESR and hypergammaglobulinaemia, with no specific pattern of changes. Histological confirmation was most frequently obtained by examination of nasal biopsy specimens, but multiple biopsies were often required. Renal biopsies showed focal proliferative glomerulonephritis but granulomatous glomerulonephritis was uncommon. Of available chest radiographs 61 per cent were abnormal, large opacities being most common. Small irregular opacities were found less often and other abnormalities were uncommon. Treatment varied widely and 10 per cent of patients received no drug therapy. This large series illustrates that even without specific treatment, patients with Wegener's granulomatosis can survive for several years and with modern treatment survival for more than a decade is possible. Conclusions about the effectiveness of the various therapies cannot be drawn from this retrospective study. Renal failure and disseminated vasculitis were the commonest causes of death; death was considered to result from complications of treatment with cytotoxic drugs or prednisolone in 6 per cent of patients.
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Novel high-affinity, low-capacity binding sites in intestinal membranes for the heat-stable toxin produced by Escherichia coli have been defined. The appearance of these sites is observed in the presence of physiological concentrations of NaCl in binding reactions. Scatchard analyses of equilibrium binding in the absence of NaCl demonstrated a single class of binding sites with KD = 1.9 x 10(-9) M and Bmax = 0.75 pmol/mg of protein. In contrast, similar experiments in the presence of NaCl demonstrated, in addition to the previously described low-affinity site, a high-affinity site with a KD of 2.1 x 10(-11) M and a Bmax of 73 fmol/mg of protein. Confirmation of the presence of high- and low-affinity sites was obtained in studies of the kinetics of ST binding. These sites exhibited similar dissociation but markedly different association kinetics. Determination of the association and dissociation constants permitted calculation of the KD's for the high- and low-affinity sites, which were 1.15 x 10(-11) M and 1.89 x 10(-9) M, respectively. These data agree closely with those obtained in studies of equilibrium binding. Furthermore, similar values for the KD's of these sites were obtained in experiments of competitive displacement of labeled ST, confirming the presence of two receptors for this toxin. Binding of ST to high-affinity sites is completely reversible and does not appear to be coupled to activation of particulate guanylate cyclase. In contrast, binding of ST to low-affinity sites appears to be partially reversible and may be coupled to activation of guanylate cyclase.(ABSTRACT TRUNCATED AT 250 WORDS)
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A statistical procedure for monitoring the health status of a community potentially exposed to a hazardous environment is presented. It utilizes two levels of investigation. Level I studies monitor routinely collected vital statistics and routes of community exposure whereas level II studies require additional data collection and are further distinguished by their design and duration. In a level I study, routine vital statistics for specified end points over a specified period of time are monitored, and the observed number of events is compared with the expected number of events for a given population. The statistical model used with this procedure employs a two-step decision rule based on the standardized mortality ratio for the study community. An "alert status" is invoked when the number of events exceeds a prescribed excess. An "action status" is indicated if the excess noted in the initial period persists or if the observed number of events in the initial period greatly exceeds expectation. Should an "action status" be justified, level II studies to determine the likely explanation for the significant excess are initiated. This could include the conduct of a "case-control" study using the exposure data available from monitoring the community.
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