Interaction of platelet plasma membranes with thrombin-activated platelets

This study described the binding of platelet plasma membranes to either control or thrombin-activated platelets. Glycoproteins in plasma membranes isolated from human platelets were labeled by oxidation with periodate followed by reduction with [3H]NaBH4. Labeled membranes were incubated with either control or thrombin-activated platelets. The amount of membranes bound was measured by separating platelets with bound membranes from solution by rapid centrifugation through 27% sucrose and determining the amount of radioactivity associated with platelets. Five- to sevenfold more membranes bound to thrombin- activated platelets than to control platelets. This enhanced binding of labeled membranes was completely inhibited by an excess of unlabeled platelet membranes. Human erythrocyte membranes had little affinity for either washed or thrombin-activated platelets and therefore did not compete for platelet-membrane binding. Binding of platelet membranes to thrombin-treated platelets was inhibited by prior incubation of the platelets with PGI2 suggesting that the enhanced binding of membranes was to activated platelets. This study demonstrates that the purified platelet membranes have functional sites that can mediate membrane binding to platelets and that quantitation of membrane binding appears to reflect the increased aggregation capability of activated platelets.     

The impact of the 2003 heat wave on daily mortality in England and Wales and the use of rapid weekly mortality estimates

This paper describes a retrospective analysis of the impact of the 2003 heat wave on mortality in England and Wales, and compares this with rapid estimates based on the Office for National Statistics routine weekly deaths reporting system. Daily mortality data for 4 to 13 August 2003, when temperatures were much hotter than normally seen in England, were compared with averages for the same period in years 1998 to 2002. The August 2003 heat wave was associated with a large short-term increase in mortality, particularly in London. Ozone and particulate matter concentrations were also elevated during the heat wave. Overall, there were 2139 (16%) excess deaths in England and Wales. Worst affected were people over the age of 75 years. The impact was greatest in the London region where deaths in those over the age of 75 increased by 59%. Estimated excess mortality was greater than for other recent heat waves in the United Kingdom. The estimated number of deaths registered each week is reported by the Office for National Statistics. The first clear indication of a substantial increase in deaths was published on 21 August 2003. This provided a quick first estimate of the number of deaths attributable to the heat wave and reflected the pattern of daily deaths in relation to the hottest days, but underestimated the excess when compared with the later analysis.     

Testicular microlithiasis: The importance of self‐examination

Aim: To explore the issue of appropriate management of testicular microlithiasis. We report the third ever case of tumour arising from a testis previously known to have microlithiasis in childhood and review the literature to provide an evidence‐based approach to management of testicular microlithiasis. Methods: Case report and review of previous literature. Results and Conclusions: Although there is a strong association between testicular microlithiasis and testicular malignancy at diagnosis, there are only three reported cases of subsequent tumour development in childhood. Testicular microlithiasis is an increasingly recognised entity. There is insufficient evidence in the current literature to support any regime of clinical surveillance. Self‐examination is the most important factor in the early detection of testicular malignancy.     

Cerebral blood flow relationships associated with a difficult tone recognition task in trained normal volunteers

Tone recognition is partially subserved by neural activity in the right frontal and primary auditory cortices. First we determined the brain areas associated with tone perception and recognition. This study then examined how regional cerebral blood flow (rCBF) in these and other brain regions correlates with the behavioral characteristics of a difficult tone recognition task. rCBF changes were assessed using H2(15)O positron emission tomography. Subtraction procedures were used to localize significant change regions and correlational analyses were applied to determine how response times (RT) predicted rCBF patterns. Twelve trained normal volunteers were studied in three conditions: REST, sensory motor control (SMC) and decision (DEC). The SMC-REST contrast revealed bilateral activation of primary auditory cortices, cerebellum and bilateral inferior frontal gyri. DEC-SMC produced significant clusters in the right middle and inferior frontal gyri, insula and claustrum; the anterior cingulate gyrus and supplementary motor area; the left insula/claustrum; and the left cerebellum. Correlational analyses, RT versus rCBF from DEC scans, showed a positive correlation in right inferior and middle frontal cortex; rCBF in bilateral auditory cortices and cerebellum exhibited significant negative correlations with RT These changes suggest that neural activity in the right frontal, superior temporal and cerebellar regions shifts back and forth in magnitude depending on whether tone recognition RT is relatively fast or slow, during a difficult, accurate assessment.      

An [35S]methionine cytotoxicity assay requiring small numbers of effector and target cells

This communication describes an assay to detect polyclonal cytotoxic activity of small numbers of effector cells. 200 tumor target cells, radiolabelled with 10,000-20,000 cpm [35S]methionine, are incubated with proportionately few effector lymphocytes in microtiter wells. The targets are sufficiently well labelled to permit detection of cytolysis caused by greater than or equal to 1000 cytotoxic cells, at effector:target ratios as low as 5:1. This method permits the rapid assay of limited numbers of effector cells, avoids lengthy culture of effector cells in order to acquire sufficient numbers, and is useful for limiting dilution analysis of cytotoxic T lymphocytes or their precursors.