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Biomedical subjects

Z Harb

Publications and source records attributed to Z Harb.

At least 19 recordsLinked to original sources
PubMed2005

Differential dependence of eosinophil chemotactic responses on phosphoinositide 3-kinase (PI3K).

BACKGROUND: Control of eosinophil migration to sites of inflammatory responses is a potentially therapeutic intervention in diseases such as bronchial asthma. Chemoattractants, their receptors and the associated signalling pathways may, therefore, be important targets for novel therapeutics. While several potentially important chemoattractants have been identified, the signalling pathways mediating their actions are incompletely understood. AIMS OF THE STUDY: The role of phosphoinositide 3-kinase (PI3K) in responses of human eosinophils to two important eosinophil chemoattractants -- platelet-activating factor (PAF) and eotaxin (CCL11) -- was studied to determine whether this enzyme activity might be crucial for eosinophil migration. METHODS: Eosinophils were isolated from atopic donor blood by immunomagnetic selection. Chemotaxis was assayed in a 96-well blind-chamber cell fluorescence assay. Respiratory burst and leukotriene C(4) secretion were also assayed. RESULTS: Two PI3K inhibitors, wortmannin and LY294002, caused concentration-dependent inhibition of PAF-induced eosinophil chemotaxis (IC(50) = 0.54 nM and 0.15 microM, respectively) but exhibited at least 100-fold lower potency against eotaxin-induced responses (IC(50) = 48 nM and >100 microM, respectively), indicating that these responses were not dependent upon PI3K. Wortmannin and LY294002 also inhibited PAF induced respiratory burst but not PAF-induced LTC(4) secretion. CONCLUSIONS: We conclude that PI3K-dependence varies with stimulus and response, and that eotaxin-induced eosinophil migration is not controlled by PI3K. This may indicate a limit to the potential of PI3K inhibitors to suppress tissue eosinophilia in diseases such as asthma.

Androstadienes↗
PubMed2002

Genetic marker variation in coastal populations of Chile.

Gene frequencies for nine genetic marker systems are presented for the following Chilean coastal populations: Paposo, Carelmapu, Laitec and Ukika. Historical and anthropological data suggest the presence of descendants of the Amerindian populations, specifically of Changos, Cuncos, Chonos and Yamanas in these populations. Results indicate that the studied groups maintain an important aboriginal genetic composition. According to Amerindian admixture estimates, the genetic isolation of coastal populations is lower than that of inland populations, suggesting that proximity to the sea facilitated gene flow. Genetic distances and dendrograms were obtained for these populations and another four Chilean Indian populations. Results agree with expectations, taking geographic isolation and non-aboriginal admixture into account.

Chile↗
PubMed1998

[Coastal Chilean populations: genetic markers in four locations].

BACKGROUND: Historical and anthropological data suggest the presence of descendents of Changos, Cuncos, Chonos and Yamanas, South American indian populations, in certain Chilean coastal villages. AIM: To assess the degree of South American indian admixture in Chilean coastal villages using protein markers, to complete the assessment of human biological diversity in Chile. SUBJECTS AND METHODS: ABO, Rh, MNS, Duffy and Kidd blood group systems were assessed in 47, 48, 55 and 24 individuals from Paposo, Carelmapu, Laitec and Ukika respectively. Phenotypic and gene frequencies were calculated. The degree of South American indian admixture was estimated from the ABO*O allele and Rh*dce haplotypes. RESULTS: High frequencies of ABO*O, Fy*a, Jk*b alleles, Dce and Ms haplotypes were found in all villages, consistent with the pattern expected for South American Aboriginal populations. The highest presence of South American indian admixture was present in Laitec with 80% and in Ukika with 74%. The figures for Paposo and Carelmapu were 60 and 65% respectively. CONCLUSIONS: According to South American indian admixture estimates, the genetic isolation of coastal populations is lower than that of inland subjects, suggesting that sea proximity facilitates gene flow.

Alleles↗
PubMed1994

[Genetic composition of the Chilean population: the Yamanas from Ukika].

The genetic composition of a group of 24 Yamana indians that survive in Puerto Williams, Navarino Island, Chile (parallel 55 south of Tierra del Fuego), was studied. Results showed that these indians have a different genetic composition than Pehuenche indians, specially for HLA system and esterase D. This fact validates the hypothesis, based on archeological and anthropological evidence, about the paleoindian origin of Yamanas.

Blood Group Antigens↗
PubMed1993

[Genetic composition of Chilean population: the Pehuenches from Trapa-Trapa].

This study describes the genetic composition of Pehuenche indians from Trapa-Trapa. The admixture analysis revealed that this group has conserved most of its pre-Columbian gene pool and therefore, is representative of the indians that lived in Southern Chile before the Spanish conquest. A relatively high frequency of a esterase D variant seems to indicate that this is a Chilean aboriginal population marker. The Chilean Pehuenches are genetically similar to their Argentinean relatives, which is not surprising since this last group crossed the Andes Mountains in historic times.

Blood Group Antigens↗
PubMed1991

Association between Rh and plasma iron binding (transferrin).

In order to establish the mechanism involved in the maintenance of the Rh polymorphism and fetomaternal compatibility relationships, we examined a sample of children from the North Area of Santiago (Chile), with respect to their growth and development patterns since 1973. This sample had shown large sib-sib segregation distortions for the Rh system. Metric variables, such as plasma protein fractions and iron, academic performance at the end of the last secondary grade and adult stature, were studied in relation to genetic markers, viz., sex, ABO, Xg, MN, Rh, haptoglobins, phosphoglucomutase, and esterase D, by means of unbalanced one way analyses of variance. Highly significant results were found for Rh phenotypes and total iron binding capacity (TIBC, transferrin). However, plasma iron did not differ significantly among Ph phenotypes. Children with the C (Rh) specificity had higher values of TIBC than non-C or c individuals (P less than 0.00001). Evolutionary considerations regarding iron transport and erythroblastosis, relationships between Rh and the transferrin receptor at the plasma membrane, and the location of the Blym-I oncogene (that shares common sequences with transferrins) close to Rh in chromosome 1 are discussed. Less significant results were found between phosphoglucomutase and stature, gamma globulin level and sex, and academic performance (history) and sex.

Analysis of Variance↗
PubMed1989

[Malnutrition, plasma proteins and immunoglobulins in Chilean puerperal women].

Healthy lying-in women admitted to the Clinical Hospital of the University of Chile, most of them belonging to the low socioeconomic of Santiago (Chile), showed a steady decrease in the plasma levels of total protein, albumin, beta-globulin, IgA, and IgM, and also a striking increase in the plasma level of alpha 1-Globulin. This trend was ascertained from december 1982 to august 1985, and the pattern of plasma protein change is similar to that found in human malnutrition. The observed changes in the immunoglobulins levels suggest a different behavior between IgM and IgA that do not cross the placenta and IgG that crosses it.

Blood Proteins↗
PubMed1982

A mother-child segregation distortion for the Rh system. New evidence for another compatibility system associated with Rh.

In the maternity service of a private hospital in Santiago, Chile, 6,974 mother-infant pairs typed for the D-d alleles of the Rh system were collected. In our analysis, all the paris attended from October 1974 to December 1975 and from January 1977 to September 1979 were used. The segregation analysis, made by means of the T mother-child matrix, assuming Hardy-Weinberg equilibrium, reveals that: Rh(-) mothers have a higher rate of admission than do Rh(+) mothers; Rh(+) mothers produce fewer Rh(-) infants than expected; and, with less significance, Rh(-) mothers produce more Rh(+) infants than expected. This leads to a reduction in the proportion of dd individuals from mothers to their children. Ethnic subdivisions of the sample, the period considered, and the extension of the antiisoimmunization therapy do not seem to affect the general pattern of the distortion. The only plausible hypothesis to explain this finding is that selection is not related to the known Rh antigenic specificities. The reduction of the proportion of dd individuals in 1 generation leads us to review models on Rh polymorphism. It seems clear that no classical compensation is possible and d must disappear unless another mechanism maintains it in populations.

Blood Group Incompatibility↗
PubMed1982

A large phenotypic sib-sib discordance for the Rh blood system. A possible new feto-maternal compatibility system.

A large sib-sib phenotypic discordance for the Rh system has been found in a longitudinal follow-up study on growth and development. Sibs born no more than 3 years later than their respective indexes show a significant tendency to have a different phenotype from that of their indexes. The hypothesis that distortion is due to eggs or fetal loss finds support in the existence of increased time intervals between indexes' and sibs' births in those cases in which the losses were suspected. Two groups of index families made according to the presence or absence of the cde haplotype in their genotype show important differences in segregation and reproductive patterns. The observed distortions cannot be explained by the differences in known antigenic Rh specificities. The existence of a new feto-maternal compatibility system would better fit these facts and would also allow the reinterpretation of several distortions associated with Rh described in the literature that have never been satisfactorily explained.

Birth Intervals↗