Biomedical subjects

S de Silva

Publications and source records attributed to S de Silva.

20 records · Page 2Linked to original sources

PubMedDate not supplied

The global distribution of length polymorphisms of the promoters of the glucuronosyltransferase 1 gene (UGT1A1): hematologic and evolutionary implications.

The promoter region of the UDP glucuronosyltransferase 1 gene (UGT1A1) contains a run of thymine-adenine (TA) repeats, usually six (TA)(6). As well as its relationship to Gilbert's syndrome, homozygosity for the extended sequence, (TA)(7) (TA)(7), has been found to be an important risk factor for hyperbilirubinemia and gallstones in patients with hemoglobin E-beta-thalassemia and other intermediate forms of beta thalassemia. To assess the importance of this polymorphism in these common disorders a wide-scale population study of the relative frequency of the size alleles of the UGT1A1 promoter has been carried out. Homozygosity for the (TA)(7) allele occurs in 10-25% of the populations of Africa and the Indian subcontinent, with a variable frequency in Europe. It occurs at a much lower frequency in Southeast Asia, Melanesia, and the Pacific Islands, ranging from 0 to 5%. African populations show a much greater diversity of length alleles than other populations. These findings define those populations with a high frequency of hemoglobin E-beta-thalassemia and related disorders that are at increased risk for hyperbilirubinemia and gall bladder disease and provide evolutionary insights into how these polymorphisms have arisen and are so unequally distributed among human populations.

Animals↗

PubMedDate not supplied

The role of traditional fertility regulation in Sri Lanka.

Among the countries of South Asia, Sri Lanka, with a birth rate of 26 per 1,000, has achieved by far the lowest fertility level. The research reported here shows that at least half of all fertility control there is still practiced by means other than those offered by the national family planning program. This paper reports on an investigation carried out by the Sri Lankan Department of Census and Statistics, employing a micro-approach to demographic research, on the levels of "traditional" methods of family planning and attitudes toward the practice of both modern and traditional contraception. It is shown that knowledge of rhythm was diffused throughout society as the cost of raising children increased during a period when other methods of family planning were not easily accessible. These traditional methods were employed efficiently and their high level of continued use arises from strong cultural resistance to the pill and IUD, based upon local interpretations of how these methods function. Thus, any programmatic effort to reduce dependence on traditional family planning might well result in higher fertility levels. In addition, low fertility among Indian Tamil workers on the Tea Estates, as early as the 1950s, probably resulted from a desire (manifested by lower levels of sexual activity and some abortion) to avoid frequent pregnancies, since pregnancy interrupts work that the female Estate workers cannot afford to miss.

Attitude↗