Human cardiovascular variability, baroreflex and hormonal adaptations to a blood donation.

1. We studied cardiovascular variability, baroreflex and blood volume regulating hormones to determine the relative roles of autonomic regulation and hormones during blood donation.2. The sympathetic response was studied by measuring the R-R interval and systolic blood pressure variability using coarse graining spectral analysis in eight blood donors. Beat-by-beat R-R intervals and blood pressure were recorded for 20 min before and 5 min after a whole-blood donation of 480+/-10 ml (about 7 ml/kg of blood volume, over 4 min). Plasma catecholamines, vasopressin, atrial natriuretic peptide, endothelin, active renin, osmolality, Na+, K+, haemoglobin and haematocrit were measured just before and after blood withdrawal.3. Blood donation led to increases in the plasma catecholamines (adrenaline, 21+/-2 versus 35+/-3 pg/ml; noradrenaline, 229+/-26 versus 323+/-37 pg/ml; dopamine, 34+/-3 versus 66+/-9 pg/ml) and in systolic blood pressure (130+/-6 versus 140+/-5 mmHg). These changes were independent of ionic or slow endocrine mechanisms. Heart rate, cardiovascular variability and the spontaneous baroreflex sensitivity did not change despite the increase in blood pressure and catecholamines. Thus the peripheral vascular control was probably involved.4. We conclude that the absence of any change in heart rate usually observed during non-hypotensive hypovolaemic stress is probably due to the sympathetic activation being counterbalanced by the high supine vagal tone at the heart and not to the heterogeneous nature of the sympathetic neural response or to changes in sympathetic and parasympathetic activity without any change in autonomic balance.

Detection of HIV-1 RNA in two consecutive blood donations screened negative for HIV antibodies.

BACKGROUND AND OBJECTIVES: An unusual serological pattern of HIV-1 seroconversion in a blood donor is described. The seroconversion panel was used to investigate the sensitivity of existing screening assays. MATERIALS AND METHODS: A volunteer blood donor who had given blood 79 times was diagnosed anti-HIV-1-antibody-positive. The heteroduplex mobility assay identified a subtype B HIV-1 strain. The frozen plasmas from the last four blood donations had been kept at -30 degrees C. They were thawed and aliquoted for subsequent testing. RESULTS: The last two blood donations contained HIV-1 RNA, 2,800 copies/ml (October 26) and 170 copies/ml (November 23). Weak anti-p24 antibodies were detected by Western blot in the October 26 sample, and a clear p24 reactivity along with a faint gp160 reactivity was observed on November 23. HIV p24 antigen was undetectable in both samples. Out of 13 screening assays, only 6 gave positive results on the November sample and 7 negative results which were obtained by 1 competitive enzyme immunoassay (EIA) and 6 of the 9 sandwich EIAs. CONCLUSION: Most sandwich EIAs gave prolonged false-negative results in the present case. p24 antigen testing was negative and would not have reduced the risk of HIV transmission.

[Irregular erythrocyte antibody screening using gel-test. Analysis of 35,882 samples]. / Recherche des anticorps irréguliers érythrocytaires par la méthode du gel-test. Analyse de 35,882 échantillons.

The results of screening for irregular blood-group antibodies in 35,882 blood-specimens using the gel-test method were analysed. The samples came from different clinics and hospital units. 1,179 samples from 728 different individuals (3.2%) contained one or several irregular antibodies. The gel low ionic strength antiglobulin test detected Kell, Duffy, and Ss antibodies with a normal frequency compared to bibliographic data, whereas Kidd antibodies seemed to be abnormally infrequent. The best detection of Rhesus antibodies was obtained with the gel enzyme test (papain). The prevalence of cold, naturally occurring, anti-Lewis and anti-P1 antibodies was low. The gel enzyme test with papain-treated red blood cells seems to be necessary for detecting Lewis antibodies (only 10 out of 95 were detected with the gel low ionic strength antiglobulin test). As a counterpart, the gel enzyme test also detected many antibodies with doubtful clinical significance: anti-E and anti-Cw reacting only with the gel enzyme test, autoantibodies with Rhesus specificity (82 examples), antibodies mimicking Jka (4 examples) and S (1 example) specificities in individuals with the corresponding antigen.