PubMed Health⌕ Search

Biomedical subjects

Z Layrisse

Publications and source records attributed to Z Layrisse.

At least 73 records · Page 4Linked to original sources
PubMed1976

Genetics of the HL-A system in a venezuelan heterogeneous population.

HL-A antigen and gene frequencies of 206 unrelated adults living in the cities of Caracas and Maracaibo have shown that this heterogeneous Venezuelan population sample possess 11 specificities of the first (LA) HL-A series and 15 specificities of the second (Four) series. HL-A2, HL-A9, HL-A5 and W5 showed frequencies higher than those observed in caucasoid populations. The most frequent haplotypes were 2, W5; 2, 5; 9, 12; 2, 12 and 2, X2. No outstandingly high value for gametic association between the alleles of the 2 HL-A series was observed, but haplotypes formed by antigens with dissimilar frequencies in Caucasoids, Negroids and American Indian tribes have shown statistically significant D values. Genetic distance calculated using the HL-A system alone showed that this population is closer to the average Caucasoid and Negroid population tested at the 5th International Histocompatibility Workshop than to 2 American Indian tribes living in the same country.

Female↗
PubMed1975

LD homozygous cells in the Warao population: a possible new allele at the LD1 locus within the main histocompatibility region in man.

A Venezuelan isolate indigenous population, the Warao, with a very large proportion of HL-A identical unrelated subjects non-reacting in MLC, has been considered a good potential source of LD homozygous cells. Cultures with lymphocytes from the members of several selected Warao families were performed with this aim and results obtained from three families are reported. In two of the families the parents share haplotype 2,5 and two of the siblings are SD double homozygous 2,5; in the third family, the common haplotype was 2,W15 and two of the siblings are also double homozygous 2,W15. Mixed lymphocyte cultures within the families have revealed that the SD homozygous children do not stimulate the cells from either parent thus being LD homozygous as well. Negative bilateral stimulation between 2,5 LD homozygous cells indicates that the LD1 allele carried by these individual's lymphocytes is the same; the negative MLC response of the 2,W15 LD homozygous cells to the 2,5 cells used as stimulators suggest either that their LD determinant is identical or the LD W15 allele is included in the LD5. As the Warao show a very large proportion of MLC identical individuals and a very high incidence of HL-A5 and W15, it is postulated that the LD allele(s) here described will be found in high frequency in this population.

Alleles↗
PubMedDate not supplied

Lymphocytotoxic antibodies in SLE patients and their relatives.

A search for lymphocytotoxic antibodies in 50 SLE patients and in 109 of their blood relatives revealed an incidence of cold-reacting antibodies of 80% and 39% respectively, as compared with 15% in 110 normal blood donors paired for age, sex, and racial origin. The antibodies were also present in 7 of 18 (39%) of the spouses of SLE patients. Lymphocytotoxic antibodies exhibited broad reactivity in all groups, although positive SLE sera showed a tendency to react with a wider variety of lymphocytes and to present higher titers than positive sera from the other groups tested.

Animals↗
PubMedDate not supplied

Use of short tandem repeats loci to study the genetic structure of several populations from Zulia State, Venezuela.

Genetic relationships between populations can be studied by comparing genotypic and allelic similarities. This investigation aims to demonstrate that selected autosomal microsatellite markers could be used to study the genetic structures of different populations living in northwest Venezuela, in Zulia State. Seven autosomal systems (CSF1PO, TPOX, TH01, vWA, D7S820, D13S317, and D5S818) were tested by PCR in a multiplex format on 688 different chromosomes from unrelated individuals living in Maracaibo, "Isla de Toas," and "San José de Heras," and from two Amerindian populations from the "Sierra de Perijá," Barí' and Yukpa. Allele frequencies, Hardy-Weinberg equilibria, genetic distances, phylogenetic trees, and ethnic admixtures were estimated. The study shows the existence of a clear genetic difference among these populations in accordance with their historic evolution. The populations of Maracaibo and "Isla de Toas" showed a triracial origin, with a large European contribution, followed by an Amerindian component and a small African component. The indigenous groups, Barí' and Yukpa, showed exclusively an Amerindian component, and "San José de Heras" showed only an African component. These results indicate that microsatellite markers are useful for molecular anthropology in a regional and worldwide context and provide important genetic information about contemporary populations of Venezuela.

Alleles↗