Effects of exposure to high partial pressures of oxygen on transtracheal influx of chloramphenicol (Chlor) were examined using in vitro perfusion of the rat trachea. Net Chlor influx decreased with increasing duration of exposure to 100% O2 from control levels of 37.0 +/- 2.4 ng.min-1.trachea-1 to 30.0 +/- 1.0 ng.min-1.trachea-1 after 36 h of exposure to 100% O2 and was further depressed after 48 h of exposure to 100% O2 60 23.0 +/- 0.9 ng.min-1.trachea-1. Examination of the O2-exposed tracheas by light microscopy showed normal morphology. In contrast, net Chlor influx was not affected by exposure to 50% O2 for 48 h. In a separate group of rats recovery from the effects of hyperoxia was studied. Within 24 h after removal from the hyperoxic environment, net Chlor influx had returned to control levels. We conclude that high partial pressures of oxygen inhibit net Chlor influx in the rat trachea at a time when tracheal histology is normal. This inhibition is a function of the partial pressure of oxygen and the duration of exposure and it is reversible after removal from the hyperoxic environment.
Abstract Background and objectives The identification of factors leading to high or low return rates among volunteer blood donors is increasingly important to maintain sufficient blood supply. A particular focus on young donors is an essential component of blood bank donor retention strategy. By means of large databases, our aim was to predict the donation frequency pattern of young donors using a random forest model, to potentially improve donor retention and increase donation frequency. Materials and methods Random forests are an ensemble learning method for classification and regression designed to produce accurate predictions that do not overfit the data. They consist of a large number of independent decision trees that operate as an ensemble and classify data into groups in a sequential manner, using time‐specific cut‐offs to differentiate groups into branches. Since a large number of trees are grown, prediction of donation behaviour in young donors will be made with limited generalization errors. Results The final dataset analysed was composed of 81 986 donors aged 18–24 at the last donation. The model correctly predicts more than 91% of the donation frequencies, with an overall error rate of 8·16% and specific error rates of 4·6% and 12·3% for ‘unreturned donor’ and ‘returned donor’ groups, respectively. The best predictive variables used in the model appear to be the number of contacts used by the marketing department, the donors’ age, the number of adverse effects during donation, the donors’ status and the ethnicity. Conclusion Our results provide relevant information for interpreting donor behaviour and could contribute to the improvement of initiatives by blood services to increase donation return rate.
Background and objectives Bacterial contamination of red blood cells ( RBC ) remains a rare but serious clinical concern. Despite the low temperature storage of RBC , some bacteria can proliferate. The impact of RBC additive solutions ( AS ), manufacturing method or donor sex on bacterial growth/survival in RBC was addressed in this pilot study. Materials and methods Using a partial pool‐and‐split design, bacterial growth/survival was assessed in intentionally inoculated RBC , manufactured separately from male and female donors using three different manufacturing methods (two whole blood [ WB ] filtration methods; one RBC filtration method), and resuspended in one of four AS : SAGM , PAGGSM , AS ‐1 or AS ‐3. At the beginning of storage, RBC were inoculated with 10 CFU /ml of either Klebsiella pneumoniae , Staphylococcus epidermidis , Yersinia enterocolitica or Propionibacterium acnes . Manufacturing, inoculation, storage (until day 42) and monitoring of bacterial growth were conducted at two sites: Canadian Blood Services and Héma‐Québec. Results Yersinia enterocolitica was the only bacterium that proliferated during storage at both sites. RBC tested at Canadian Blood Services had higher bacterial concentrations than those at Héma‐Québec ( P = 0·0044). At Héma‐Québec, where two different manufacturing methods were used, Y. enterocolitica reached significantly higher bacterial concentrations in AS ‐3 RBC ( WB filtration method) compared to units prepared in the other three AS ( RBC filtration method; P < 0·05). Bacterial survival/growth dependent on donor sex was not uniformly noted. Conclusion Only one of four bacteria grew under RBC storage conditions. The results indicate that RBC manufacturing variables, rather than AS or donor sex, affect bacterial growth in RBC .
Abstract Background Hepatitis B core antibody (anti‐HBc) screening has been implemented in many blood establishments to help prevent transmission of hepatitis B virus (HBV), including from donors with occult HBV infection (OBI). We review HBV screening algorithms across blood establishments globally and their potential effectiveness in reducing transmission risk. Materials and Methods A questionnaire on HBV screening and follow‐up strategies was distributed to members of the International Society of Blood Transfusion working party on transfusion‐transmitted infectious diseases. Screening data from 2022 were assimilated and analyzed. Results A total of 30 unique responses were received from 25 countries. Sixteen respondents screened all donations for anti‐HBc, with 14 also screening all donations for HBV DNA. Anti‐HBc prevalence was 0.42% in all blood donors and 1.19% in new donors in low‐endemic countries; however, only 44% of respondents performed additional anti‐HBc testing to exclude false reactivity. 0.68% of anti‐HBc positive, HBsAg‐negative donors had detectable HBV DNA. Ten respondents did universal HBV DNA screening without anti‐HBc, whereas four respondents did not screen for either. Deferral strategies for anti‐HBc positive donors were highly variable. One transfusion‐transmission from an anti‐HBc negative donor was reported. Discussion Anti‐HBc screening identifies donors with OBI but also results in the unnecessary deferral of a significant number of donors with resolved HBV infection and donors with false‐reactive anti‐HBc results. Whilst confirmation of anti‐HBc results could be improved to reduce donor deferral, transmission risks associated with anti‐HBc negative OBI donors must be considered. In high‐endemic areas, highly sensitive HBV DNA testing is required to identify infectious donors.
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