The incidence of cardiovascular diseases is increased in winter months. Recent studies have shown seasonal changes in plasma viscosity, fibrinogen, and factor VII activity with elevated levels during winter. An increase in these factors generates a "hypercoagulable state," which may lead to a rise in cardiovascular morbidity and mortality. It has been suggested that an increase in upper respiratory infections might be the underlying cause for the raised acute-phase reactants, in particular fibrinogen, during the winter season. We investigated seasonal variations of 26 parameters, determining blood rheology and hemostasis in 16 healthy volunteers (8 men and 8 women) aged 20 to 41 years. They were seen at monthly intervals over a period of 1 year. Seasonal variation with peak fitted values in the winter months was found for plasma viscosity (P < .001 for the seasonal difference), red blood cell deformability (P < .001), whole blood viscosity (P < .001), hemoglobin (P < .001), hematocrit (P < .001), mean corpuscular volume (P = .001), platelet count (P = .01), alpha 1-glycoprotein (P < .001), fibrinogen (measured by immunonephelometry; P < .001), plasminogen activator inhibitor-1 (P = .002), LDL cholesterol (P = .003), and triglyceride levels (P < .001). HDL cholesterol (P < .001) and cortisol (P = .001) showed inverse seasonal patterns, with a maximum during summertime. No statistically significant seasonal variations were seen for red blood cell aggregation, complement factor C4, total cholesterol, ceruloplasmin, haptoglobin, white blood cell count, and plasminogen. These data do not support the hypothesis that increased morbidity and mortality from cardiovascular diseases during winter may be mainly attributable to increased synthesis of acute-phase proteins due to infections. The cause for the seasonal variations in rheological and hemostatic parameters remains unclear and should be studied in more detail.

Immunofluorescence and electron microscopy were used to study the development and cytological distribution of dengue-2 virion and nonvirion antigens in monkey kidney cells. The type and combination of fixatives were found to affect the intensity of fluorescence. Paraformaldehyde fixation alone resulted in a low level of fluorescence, but an additional fixation step with ethanol or acetone resulted in maximum staining. No fluorescence was obtained after fixation with glutaraldehyde alone or in combination with other solvents. Methanol caused selective ablation of fluorescence by antibody to purified virions. Dengue-specific fluorescence that was most intense in the perinuclear area radiated -in a granular pattern of decreasing intensity into the cytoplasm. The perinuclear fluorescence was associated with nonvirion antigens and the cytoplasmic fluorescence was associated with virion antigens. Electron micrographs of infected cells revealed vesicular bodies with reticular electron-dense centers, clusters of structurally complete virions deep within the endoplasmic reticulum, and single virus particles in vacuoles near the periphery of the cell. 809 on July 15, 2020 by guest http://iai.asm.org/ Downloaded from

post partum, The mechanism of this hypoglycemia is unexplained. quired in order to &train live, full term litters in 10 of thee 11 pregnancies observed. _ -( 6 ) A:dministration of insulin was not re-

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The capacity of protamine sulfate to combine with and precipitate considerable tissue debris from certain virus suspensions without significantly decreasing their infectivity or antigenicity has been reported (Warren, Weil, Russ, and Jeffries, 1949). In the case of certain viruses it has been found that concentrating the protamine-clarified suspensions in the ultracentrifuge yields sediments which can be further purified by enzymic digestion. Further ultracentrifugation of the digest yields preparations of greater purity, as measured by the ratio of infectivity to nitrogen content. Observation in the electron microscope and the analytical ultracentrifuge indicates that the final product has considerable