A pilot study to determine the normal haematological indices for young Malawian adults in Blantyre, Malawi.

BACKGROUND: Reference ranges for haematological and other laboratory tests in most African countries are based on populations in Europe and America and, because of environmental and genetic factors, these may not accurately reflect the normal reference ranges in African populations. AIM: To determine the distribution of haematological parameters in healthy individuals residing in Blantyre, Malawi. We also examined the effect of sociodemographic and nutritional factors on the haematological variables. METHODS: We conducted a proof-of-concept cross-sectional study, involving 105 healthy blood donors at Malawi Blood Transfusion Service in Blantyre. Eligible participants were HIV-negative males and females, aged 19 to 35 years, who did not have any evidence of acute or chronic illness, or blood-borne infection. We performed the haematological tests at the Malawi-Liverpool Wellcome Trust laboratory in Blantyre, and the screening tests at Malawi Blood Transfusion Service laboratories. RESULTS: Out of 170 consenting healthy volunteers, haematological results were available for 105 participants. The proportions of results which were below the lower limit of the manufacturer's reference ranges were 35.2% (37/105) for haemoglobin, 15.2% (16/105) for neutrophils, 23.8% (25/105) for eosinophils, and 88.6 % (93/105) for basophils. The proportions of results that were above the upper limit of the manufacturer's reference ranges were 9.5% (10/105) for platelets and 12.4% (13/105) for monocytes. We also observed that the mean leucocyte and basophil counts were significantly higher in males than females (p = 0.042 and p = 0.015, respectively). There were no statistically significant differences in haematological results observed among different ethnic, age, and body mass index groups. CONCLUSIONS: Over half of otherwise healthy study participants had at least one abnormal haematological result, using previously established foreign standards. More detailed studies are needed to establish locally relevant normal ranges for different age groups and other demographic characteristics of the Malawian population. This will lead to accurate interpretation of laboratory results.

Validation of the haemoglobin colour scale for screening blood donors in Malawi.

BACKGROUND: In 2009 Malawi introduced a new protocol to screen potential blood donors for anaemia, using the WHO Haemoglobin Colour Scale (HCS) for initial screening. Published studies of the accuracy of the HCS to screen potential blood donors show varying levels of accuracy and opinion varies whether this is an appropriate screening test. The aim of the study was to assess the validity of the HCS, as a screening test, by comparison to HemoCue in potential blood donors in Malawi. STUDY DESIGN AND METHODS: This was a blinded prospective study in potential blood donors aged over 18 years, at Malawi Blood Transfusion Service in Blantyre, Malawi. Capillary blood samples were analysed using the HCS and HemoCue, independent of each other. The sensitivity and specificity of correctly identifying ineligible blood donors (Hb ≤ 12 g/dL) were calculated. RESULTS: From 242 participants 234 (96.7%) were correctly allocated and 8 (3.3%), were wrongly allocated on the basis of the Haemoglobin Colour Scale (HCS) compared to HemoCue, all were subjects that were wrongly accepted as donors when their haemoglobin results were ≤ 12.0 g/dL. This gave a sensitivity of 100% and specificity of 96.7% to detect donor eligibilty. The negative predictive value of the HCS was 100% but the positive predictive value to identify ineligible donors on the basis of anaemia was only 20%. CONCLUSIONS: Initial screening with the HCS correctly predicts eligibility for blood donation in the majority of potential blood donors at considerable cost saving compared with use of HemoCue as the first line anaemia screening test, however, by this method a small number of anaemic patients were allowed to donate blood.

Development and evaluation of a new paediatric blood transfusion protocol for Africa.

Severe anaemia is a common childhood emergency in developing countries. Practical evidence-based guidance on when to transfuse, volume of transfusion and ideal duration of transfusion is lacking. The aim of this study is to develop a paediatric transfusion protocol for use in under-resourced environments and evaluate its usability in a busy African hospital setting. A paediatric transfusion protocol based on the WHO Guidelines was developed for the Queen Elizabeth Central Hospital (QECH), Blantyre, Malawi. On the basis of simple bedside clinical features of respiratory, cardiovascular and neurological compromise, the protocol allocates children with severe anaemia (haemoglobin

The prevalence of red-cell antigens and antibodies in Malawi.

As there were no reliable data in Malawi for the prevalence of red cell alloantibodies or antigens in the population, a study was conducted to screen 1000 patients for the presence of antibodies and to type them for ABO, RhD, C, c, E, e and K antigens and to test 500 donors for these antigens plus Fy(a), Fy(b), Jk(a), Jk(b), S and s. Red cell antibodies were identified in 11 patients [1.1%]; 2 were anti-D, 2 anti-S, 1 anti-Le(a+b) and 6 anti-M, 4 of which were found in non-transfused males suggesting they might be naturally acquired. The antigen frequencies found were similar to those previously published for Central Africa but 98.2% of donors were found to be Fy(a-b-). All patients tested were K negative and only three donors were found to be K positive, one being a Caucasian. Approximately 3.5% of Malawians are D negative, lower than the usual 8% quoted for Black Africans. These data confirm the assumption that pre-transfusion antibody screening is not currently required but that use of the indirect antiglobulin test in the cross-match is necessary. Haemolytic disease of the newborn (HDN) appears to be rare, or under reported, in Malawi, and more work is needed to find the real incidence of this condition.

Regulation of squalene synthetase and squalene epoxidase activities in Saccharomyces cerevisiae.

Squalene synthetase (EC 2.5.1.21) and squalene epoxidase (EC 1.14 99.7) activities have been measured in cell-free extracts of wild type yeast grown in aerobic and semi-anaerobic conditions as well as in sterol-auxotrophic mutant strains grown aerobically. The results show that both enzymes are induced resulting in an almost two- to five-fold increase in enzymatic activities in mutant strains containing limited sterol amounts and are repressed in the wild type strain cultured in anaerobiosis in excess of sterol. The results show also that squalene epoxidase is repressed by lanosterol, and that the mevalonic acid pool may regulate squalene synthetase levels. The large change in the activities of the two enzymes, depending on the sterol needs of the cells, as well as their low specific activities in comparison with those of the enzymes involved in the early stages of sterol synthesis strongly suggests that squalene synthetase and squalene epoxidase are of importance in regulating the amount of sterol synthesized by yeast.

In vitro assay of squalene epoxidase of Saccharomyces cerevisiae.

We describe a simple assay for measuring squalene epoxidase specific activity in Saccharomyces cerevisiae cell-free extracts, by using [14C] farnesyl pyrophosphate as substrate. Cofactor requirements for activity are FAD and NADPH or NADH, NADPH being the preferred reduced pyridine nucleotide. Squalene epoxidase activity is localized in microsomal fraction and no supernatant soluble factor is required for maximum activity. Microsomal fraction converted farnesyl pyrophosphate into squalene, squalene 2,3-epoxide and lanosterol, showing that squalene 2,3-epoxide-lanosterol cyclase is also a microsome-bound enzyme. We show also that squalene epoxidase activity is not inhibited by ergosterol or lanosterol, but that enzyme synthesis is induced by oxygen.