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Biomedical subjects

D M Baird

Publications and source records attributed to D M Baird.

7 recordsLinked to original sources
PubMed1995

Mechanisms underlying telomere repeat turnover, revealed by hypervariable variant repeat distribution patterns in the human Xp/Yp telomere.

Sequences immediately adjacent to the human Xp/Yp telomere exhibit a high frequency of base substitutional polymorphisms, together with almost complete linkage disequilibrium, to create only a few diverged haplotypes. This sequence divergence has been used to develop a PCR-based system for mapping the distribution of the telomere (TTAGGG) and variant repeats (TGAGGG and TCAGGG) at the proximal end of the telomere repeat array. The distribution of these repeats is extremely variable. Almost all Xp/Yp telomeres are different, indicating a high mutation rate. Some telomere maps associated with the same flanking haplotype show similarities, identifying subsets of telomeres that share a recent common ancestry. Mechanisms underlying the rapid turnover of repeats at the proximal end of the Xp/Yp telomere include intra-allelic processes, such as slippage during replication. Inter-allelic exchanges may occur occasionally, but telomerase activity probably plays only a minor role in the germline turnover of proximally located telomere and variant repeats.

Alleles↗
PubMed1994

A subterminal satellite located adjacent to telomeres in chimpanzees is absent from the human genome.

One of the significant unresolved differences between the karyotypes of humans and African apes is the presence of positively staining G-bands at the ends of many chromosome arms in the chimpanzee and gorilla but absent from human chromosomes. Using a telomere anchored PCR strategy, we have isolated DNA from a subterminal satellite, composed of a 32 basepair A-T rich repeat, from the chimpanzee genome that hybridizes to all the additional terminal bands and at two interstitial sites. The satellite is more abundant in gorillas and is not detected in humans or orangutans. Furthermore, there is no similarity between other chimpanzee telomere-junction clones and human subterminal sequences, and therefore the organization of sequences adjacent to telomeres is very different between these closely related primates.

Animals↗
PubMed1983

Tobacco smoking among students at the University of the Witwatersrand, Johannesburg.

The epidemiology of smoking, factors which motivated students at the University of the Witwatersrand, Johannesburg, to smoke, to continue smoking or to stop smoking, and student awareness of the health hazards of smoking were investigated. Analysis of a random sample comprising 13% of the 12426 full-time undergraduate students at the university revealed that 22% smoked, 17% were ex-smokers and 61% had never smoked. Most of the smokers smoked between 10 and 20 cigarettes a day. The years between the ages of 17 and 19 years appear to be important in determining whether students become regular smokers or stop smoking.

Adolescent↗