Abridging medical education.
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Biomedical subjects
Publications and source records attributed to R B Dawson.
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Six erythrocyte antigen systems and the HLA system were evaluated to establish their practical value in 500 cases of disputed paternity. The actual results were very close to predicted values. HLA testing is expected to detect 92% and red cell testing is expected to detect 67% of men falsely accused in paternity suits. The findings of this study show that HLA detected 94% and red cell testing detected 69% of 107 men falsely accused in 500 paternity cases. In order of sensitivity, Rh, MNSs, and ABO were the most useful erythrocyte marker systems. There were six out of 107 cases in which exclusions would have been undetected if red cell typing had not been performed. Five of the six cases involved "common" HLA haplotypes.
A search was conducted to find evidence of possible incestuous unions between the biologic parents of children involved in 2500 paternity cases. Suspicion was raised when either (1) a mother and her child possessed identical HLA phenotypes, or (2) the child appeared to be possibly homozygous for one maternal haplotype (i.e., one of the child's HLA haplotypes was a blank). These mother-child HLA-haplotype dualisms (MHDs) occurred in 5% of all cases. Frequency of exclusion of the accused men in cases demonstrating MHD, was compared with the remaining paternity cases. No significant difference was found in overall exclusion rates between MHD cases and controls when exclusion produced by HLA and red cell antigen systems were observed. However, there was a greater rate of exclusion in MHD cases when comparing exclusions produced by red cell antigen systems regardless of whether HLA tests excluded paternity (p less than 0.025). MHD cases involving teenaged mothers differed from control cases in frequency of exclusion of paternity only on the basis of red cell antigen phenotyping (p less than 0.005). The HLA system's usefulness in paternity testing is diminished when there is MHD; multiple, independently-inherited systems are relatively more useful in these circumstances. The search method detects only half of potential incest cases; proof of incest requires more extensive testing for homozygosity among other polymorphisms. Since calculations of likelihood of paternity are inappropriate in cases involving close consanguinity, detection and follow up studies are important. Data suggest that one-fifth of MHD cases may involve first degree consanguinity and that the incest rate among paternity cases may be as high as 2%.
Interest has been renewed in CPD-adenine as a long-term liquid blood preservative. The question of whether the metabolic product of adenine, 2,8-dioxyadenine was toxic to humans has apparently been resolved by extensive animal and human studies in favor of there being no potential toxicity in the amounts used in blood preservation. Sweden is adopting CPD-adenine (0.25 mM) as its national blood preservative after ten years of clinical experience in trials. They have shown that each additional week of storage time beyond the current three weeks with CPD results in a 50 per cent reduction of wasteage caused by outdating. They are adopting the 35-day time for regular use with 42 days for an emergency reserve supply. However, many units of blood in the U.S. are stored as packed red blood cells and the question has been raised as to whether there is sufficient glucose in the preservative to maintain red blood cell metabolism in the packed cell unit. The present investigation indicates that there is sufficient glucose for 35 days of packed cell storage in CPD-adenine (0.25 mM) but in some units this might be marginal at 42 days of storage.
CPD-adenine is being adopted in Europe for five weeks for regular blood bank storage and six weeks for emergency use storage. There may be a need to maintain normal levels of 2,3-DPG during this prolonged storage time. In a pilot study from this laboratory, improved 2,3-DPG maintenance was noted with DHA and pyruvate during the fifth and sixth weeks of storage. DHA and pyruvate are relatively unstable in aqucous solutions and in the present study extra care was taken with their experimental use. The additive effect of using DHA and pyruvate together in maintaining 2,3-DPG was confirmed in this study in which significant improvements were seen as early as the seventh day of storage.