Human blood group O cells were converted to B-active cells by incubation
with uridine diphosphate D-galactose and enzyme preparations from group B stomach
mucosa or serum from group B or AB subjects. The specificity of the converted cells was
tested by their reaction with human and rabbit anti-B sera and by the specific inhibition
of the newly acquired agglutinating properties by soluble blood group B substance and
B-active oligosaccharides. The failure of the α-galactosyltransferases to transform cells
of the ‘Bombay’ O(h) phenotype into B-active cells supports the concept that H-active
structures are the acceptors of the transferred galactosyl residues.
Background: Gastro-oesophageal reflux disease (GERD) is difficult to diagnose without invasive testing. Peptest (RD Biomed, Hull, UK) is a recently marketed diagnostic tool which aims to quantify salivary pepsin as a marker of reflux, providing a rapid alternative to invasive procedures.
Aim:To evaluate optimal timing for sampling, and to evaluate the accuracy of Peptest against an independent measure.
Methods: Thirty diagnosed GERD patients (12 female, mean age 49 [range 20-72])and 20 asymptomatic subjects (14 female, mean age 56 [range 21-56]) were subject to diurnal saliva sampling, with additional samples for 60 minutes following self-reported reflux symptoms and triggering of a proximal reflux alarm. Saliva samples were split and were analysed by both Peptest and ELISA with operators for each blinded to sample identity.Results: Salivary pepsin was detectable in most patients and most volunteers. Peptest scores were significantly lower for patients than controls (P < 0.005). ELISA scores showed no difference between patients and controls. There was no effect of diurnal sampling time (P = 0.75) or time after symptoms (P = 0.76) on Peptest readout. There was no correlation between Peptest and Pepsin ELISA (P = 0.55);Bland-Altman analysis suggested no agreement between the tests (P = 0.414).Receiver-operator curve suggests that neither Peptest (P = 0.3328) nor pepsin (P = 0.4476) is useful for predicting GERD.Conclusion: Salivary pepsin is not a reliable tool for the diagnosis of GERD.Caroline Race and Joanna Chowdry made an equal contribution to this work. Bernard M. Corfe and Stuart A. Riley made an equal contribution to this work.
A discrepancy between red cell and serum grouping in the ABO system found in routine testing of a healthy blood donor led to recognition of blood group chimerism. The red cells of the propositus grouped as Al and his serum as AB. He was found to have a mixture of 99% A, cells and 1% B cells, and the blood of his twin sister also contained 99% A, and 1% B cells. In each twin the two populations of red cells also differed in Rhesus, MN, and Xg groups. The genotype of the twins was established by the presence of blood group substances in their saliva, the presence or absence of A , h b substance on their red cells, the distribution in their serum of transferases determined by the A and B genes, and by chromosome studies on lymphocytes.
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