Automatic volumetric capillary cytometry for counting white cells in white cell-reduced plateletpheresis components.

BACKGROUND: As the benefits of white cell (WBC)-reduced blood components become increasingly apparent, the need has arisen for a simple, automated WBC-counting technique that is sensitive to low WBC concentrations. Automated volumetric capillary cytometry was evaluated for its ability to quantify residual WBCs in WBC-reduced plateletpheresis components. STUDY DESIGN AND METHODS: The volumetric capillary cytometry system evaluated uses a laser to excite fluorescent dye-labeled nucleated cells. The number of nucleated cells per microliter is reported. Four studies were performed: linearity, precision of results near the value of 5 x 10(6) WBCs per unit, the limit of detection, and correlation to the Nageotte manual counting method. RESULTS: Assay values correlated to expected values (range, 0-125 WBC/microliter) with an r2 > 0.99. In the range of 5 x 10(5) WBCs per unit the CV was 8.5 percent, and concentration differences of 0.15 log10 were detectable. The limit of detection was 1.0 WBCs per microliter (95% upper confidence limit). The assay correlated to the Nageotte method with an r2 of 0.98, slope of 1.0, and y-intercept of 2.0 WBCs per microliter. Assay results were 10 to 15 percent higher than Nageotte results, in samples with values near 5 x 10(6) WBCs per unit. Technician time per sample was 2 to 3 minutes. CONCLUSION: Volumetric capillary cytometry is precise and sensitive to small differences in WBC concentration in the range of clinical interest. The device provides an efficient new method for quality assurance and control of WBC-reduced plateletpheresis products.

Cyclic nucleotides and ethanol tolerance and dependence.

Acute ethanol administration decreases cyclic AMP levels in brains of some animal strains. The ethanol-induced decrease of cyclic GMP levels cannot be blocked by intraventricular infusion of calcium but it can be prevented by pretreatment with pyrazole. Although cyclic AMP levels in the cerebral cortex change reciprocally after acute ethanol administration and during withdrawal, the increase observed during withdrawal is probably secondary to some withdrawal processes. Ethanol decreases cerebellar GABA levels only in rats which are stressed prior to sacrifice. Chronic intraventricular infusion of calcium increased the intensity of an acoustic startle response during ethanol withdrawal while EGTA infusion delayed the development of tolerance to the hypothermic effect of ethanol. The ratio of cyclic GMP to GABA levels is postulated to be important for expression of the withdrawal syndrome.