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Biomedical subjects

K Davies

Publications and source records attributed to K Davies.

At least 127 records · Page 7Linked to original sources
PubMed1983

On the genetic length of the short arm of the human X chromosome.

Published estimates of the length of the human X chromosome are unreliable because they are based on scanty linkage data and complex assumptions about the frequency and distribution of chiasmata in female meiosis. In recent months we have established linkage between restriction fragment length polymorphisms (RFLPs) and several genes on the short arm of the X chromosome. These and previous data can be combined to construct a continuous linkage map spanning the short arm from the Xg gene to the centromere. They suggest that the genetic length of the Xg-Xcen segment may be in the order of 75-90 cM.

Chromosome Mapping↗
PubMed1983

Huntington's chorea in South Wales: mutation, fertility, and genetic fitness.

A study of mutation, biological fitness, and patterns of family building in Huntington's chorea has been carried out, based on a previously reported population study of the disorder in South Wales. No unequivocal new mutation was identified among 101 kindreds containing 418 affected persons, which supports the extreme rarity of mutation in this disorder. Increased values of fertility and fitness were found, both in relation to unaffected relatives and to the general population of the area. The proportion of unmarried persons and pattern of family building was comparable in affected and unaffected subjects, and no correlation with age at onset or mode of clinical presentation could be found.

Adult↗
PubMed1981

Huntington's Chorea in South Wales. A genetic and epidemiological study.

A study of Huntington's Chorea in South Wales has shown a prevalence of 7.61 per 100,000 in the counties of Gwent and Glamorgan, with a total population of 1.7 million. Heterozygote frequency is close to 1 in 5,000. Total ascertainment within this area has been attempted, and experience since conclusion of the study has shown no patients who have been omitted apart from those originating outside the area and those new cases with no living affected relatives. Analysis of migration patterns suggests that around 20% of cases in each generation arise from outside Glamorgan and Gwent and that around 12% of first-degree relatives of indigenous cases have left the area. The survey has formed the initial phase of a long-term prospective study of the disease involving systematic genetic counselling of all high-risk individuals and regular surveillance to monitor possible trends in future prevalence.

Genetic Counseling↗
PubMed1981

Interaction of antibody-aggregated C4 and guinea-pig red cells: coagglutination phenomenon of Bordet and Gengou.

The component of bovine serum (coagglutinogen) responsible for coagglutination of guinea-pig red cells has been shown to be c4, as anticipated from our previously reported findings on human serum. To effect coagglutination, the C4 needs to be aggregated by antibody; thereby probably increasing the avidity of the C4 for the receptors on guinea-pig red cells. The coagglutinating activity is lost if univalent Fab anti-C4 is used, but it can be restored by adding IgG antibody to the Fab. A procedure is described for producing antibody reagents to human or bovine C4 by injecting guinea-pigs with well-washed coagglutinated guinea-pig red cells.

Animals↗
PubMed1981

Effects of self-instructional training on cognitive impulsivity of mentally retarded adolescents.

The cognitive style dimension of reflection-impulsivity was assessed for 27 retarded adolescents using the Matching Familiar Figures Test. The most impulsive adolescents subsequently received training in self-instruction while observing a reflective model or observed the model without specific training in self-instruction. Posttraining measures indicated that the self-instruction procedure produced significantly more reflective responding than did the model-alone procedure. The results also suggested the presence of a developmental lag in cognitive style among the retarded children compared to recent norms for nonretarded children. The finding that the retarded youth were responsive to self-instructional training appears to be inconsistent with Luria's (1961) contention that retarded individuals are incapable of using the language-based second signaling system to influence and control their own behavior.

Adolescent↗
PubMed1979

Huntington's chorea. The basis for long-term prevention.

A long-term programme to reduce the incidence of Huntington's Chorea has been established in South Wales, based on a study of all individuals known to be affected or at high risk in a defined population of 1.7 million people. Systematic but non-directive genetic counselling is being given to all adults at risk, accompanied by regular follow-up to provide both further information and practical support where required. The number of observed and projected new cases of the disorder born between 1900 and 1970 has remained almost constant, despite a progressive reduction in birth-rate in the general population during this period. Prospective monitoring of all births in the high-risk population will allow an estimate to be made of future trends and will show whether preventive measures are having any significant effect on the future incidence of the disorder in the population.

Adolescent↗
PubMed1979

Separation and identification of the carotenoid pigments of stigmata isolated from light-grown cells of Euglena gracilis strain Z.

Thin layer chromatography of the carotenoid pigments of stigmata isolated from light grown cells of Euglena gracilis strain Z resolved 29 compounds, of which 16 could be eluted and their absorption spectra recorded. Seven of these compounds were identified by a combination of co-chromatography with authentic compounds and by chemical tests, one of these compounds (beta-carotene) was further identified by mass spectrometry. The major carotenoids were found to be beta-carotene, diatoxanthin and diadinoxanthin which together comprised approximately 60% of the stigma pigments. In addition significant quantities of canthaxanthin, echinenone and cryptoxanthin were isolated and a possible carotenoid ester was detected. The results of this analysis are compared with those of previous workers and the significance of the findings is discussed.

Animals↗