[The effect of the hemocoagulation status in hemodialyzed patients on the patency of arteriovenous fistulas]. / Vliv hemokoagulacního stavu hemodialyzovaných nemocných na pruchodnost arteriovenózních pístelí.

In a group of regularly haemodialyzed patients the authors examined 15 who suffered from repeated obliterations of subcutaneous a-v fistulae and compared the results with findings in 14 patients before the establishment of the first fistula which did not become obliterated for a period of six months. The group of patients with repeated obliterations had a significantly lower level of antithrombin III, a higher number of thrombocytes with an increased aggregation induced by low concentrations of adenosine diphosphate and adrenaline. The authors assume that investigation of coagulation mechanisms in frequent obliterations of subcutaneous a-v fistulae can help towards therapeutic prevention and as a model situation for the investigation of the development of thrombosis in general.

The effect of pirenzepine on the functions of human platelets.

Despite the very high chemical similarity of pirenzepine (P) to the selected tricyclic antidepressive drugs (TCAD) (imipramine, desimipramine, nortriptyline and amitriptyline), P has a distinctly different effect on platelets, in particular, on serotonin uptake and platelet aggregation. Using two groups of nine healthy volunteers, mean age 27.7 and 27.5 years, respectively, assessment of the two indicators in vitro helped us to eliminate the possibility of a drug induced defect of the two thrombocyte functions, i.e. their aggregation and serotonin uptake. There is therefore, no reason to fear the danger of decreased hemocoagulation in ulcer patients treated with P for gastrointestinal hemorrhage. The results obtained in vivo using two tests which showed the level of platelet activation associated with release of a specific platelet protein (beta-thromboglobulin in platelet-poor plasma) and malondialdehyde in thrombocyte-rich plasma ruled out any changes, specifically their increase, and have disproved any kind of stimulating activity of P on thrombocyte reactivity.

Changes in blood tryptophan level during sleep deprivation.

Prolonged sleep deprivation elicits a significant elevation of the plasma level of free tryptophan which appears to be involved in increased excretion of 5-HIAA during this state through enhanced 5-HT synthesis.