PubMed Health⌕ Search

Biomedical subjects

C Y Valenzuela

Publications and source records attributed to C Y Valenzuela.

At least 19 recordsLinked to original sources
PubMed1992

[Typhoid fever in children: association with blood phenotypes ABO, Rh and MNSs].

The hypothesis that blood phenotype B is associated to typhoid fever either directly or interacting with other phenotypes of the Rh or MNSs blood systems was tested. 256 children from the Northern Area of Santiago (Chile) with bacteriologically confirmed typhoid fever and 329 afebrile controls matched by age and gender from the same population, were studied. Association was found between phenotype RH3 and protection against disease for the whole group (OR = 0.67; p < 0.042) and for males (OR = 0.05; p = 0.014) although the gender-RH3 interaction was at the limit of significance. RH8 and Ss phenotypes were associated to increased susceptibility (OR = 1.83; p < 0.034 and OR = 1.56; p = 0.01, respectively). Controlling RH3 and Ss phenotypes by B, increased their effects (OR = 0.26; p = 0.04 and OR = 3.42; p = 0.026, respectively), but interactions did not reach statistical significance. These results show a susceptibility cline whose implications and applicability deserve further studies. A high proportion of S. paratyphi B (23.8%) appeared in this series, which may imply sample heterogeneity. The meaning of these findings need further epidemiological and genetic studies.

Blood Group Antigens↗
PubMed1992

[Study of the Widal test phenotypic expression of blood groups ABO, Rh and MNSs in patients with typhoid fever].

The significance of the Widal test (WT) as a phenotypical expression was investigated in a cross-sectional study of 244 children from the Northern Area of Santiago (Chile) with bacteriologically confirmed typhoid fever (TF) due to S. typhi (183 cases) and S. paratyphi B (61 cases). The working hypothesis was that if the parasite-host relationships were similar for these two agents the immune response, as measured by the Widal test, should be similar. An association between test response and etiology was found consisting of a significantly higher proportion of positive response, in cases due to S. paratyphi B as compared with those due to S. typhi, (OR = 2.13; 95 Cl% = 1.06, 4.32; p = 0.02). Stratified analysis showed that although the association between etiologic agent and Widal test response persisted within all strata, significant interactions could be shown as evidenced by the magnitude of the associations, which varied according to blood phenotypes as well as gender (Mantel-Haenszel test for heterogeneity for 0, p < 0.034; for RH5 p < 0.033; for SS, ss p < 0.056; and gender p < 0.033). These results support the hypothesis that the Widal test response is a phenotypical marker eventually useful for studying human genetic heterogeneity in typhoid fever. The implications of these findings regarding previous study results and the possible role of S. paratyphi B in typhoid fever and its related conditions are discussed.

Adolescent↗
PubMed1992

ABO segregation distortion in Visakhapatnam, India.

Distortions in mother-infant, mother-child and father-child segregation for the ABO system as well as in the sex of offspring are described in a sample from a maternity service and from families of Visakhapatnam, India. Some distortions follow the expected fetomaternal incompatibility depression, others the expected feto-maternal induction of tolerance, and some remain unexplained. A differential action of selective factors on male and female fetuses, infants and children was also found, but no hypothesis could be postulated to explain it. The mother-infant matrix was found to be different from the mother-child matrix probably due to the inclusion of the reproductive time only in the mother-infant matrix. Unexpectedly, father-child segregation distortions were also found.

ABO Blood-Group System↗
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↗
PubMed1991

Segregation distortions of the ABO and Rh systems in malformed newborns.

This study compares the segregation of the ABO and Rh systems between malformed newborns and a control group with two purposes: (1) to evaluate the participation of genetic factors associated with these blood groups in the production of congenital malformations, and (2) to prove, indirectly, the existence of reproductive losses associated with congenital malformations. The newborns and their mothers were typed for ABO and Rh groups. Gene frequencies were similar in malformed and control newborns. In the female malformed newborns, an excess of O-B pairs and a deficit of B-B pairs in the ABO system, and an excess of Rh(-)-Rh- pairs in the Rh system were found.

ABO Blood-Group System↗
PubMed1985

Selective interactions among Rh, ABO, and sex ratio of newborns.

The hypothesis that the Rh and ABO blood systems behave like the HLA system in relation to mother-conception tolerance-rejection mechanisms was tested in 25,501 mother-infant pairs. According to this hypothesis, heterozygotes carrying a paternal gene that is not present in their mothers should be better tolerated than homozygotes. Significantly more BO infants born to AO mothers. AO infants born to BO mothers, Rh(+) heterozygotes born to Rh(-) mothers, and less significantly AO infants born to OO mothers confirm the hypothesis. Fewer homozygotes occurred in Rh(-) infants born to Rh(+) mothers and in O infants born to non-O mothers. Deviations from the Hardy-Weinberg equilibrium found in the ABO system were modified by the Rh and sex of the infant. These data strongly support the hypothesis that at least two feto-maternal systems influence the destiny of pregnancies: the classical known incompatibility system which operates late in pregnancy and a new one which is based on the induction of maternal tolerance early in pregnancy: maternal tolerance seems to be better elicited by heterozygous eggs or embryos carrying a gene not present in the mother. The data also support the hypothesis that the sex ratio is influenced by feto-maternal tolerance-rejection mechanisms associated with the ABO and Rh systems.

ABO Blood-Group System↗
PubMed1983

Pubertal origin of the larger sex dimorphism for adult stature of a Chilean population.

Students aged 6 to 20 years attending the public schools in the Northern Area of Santiago, Chile, were examined to search for the developmental origin of the large sex dimorphism in adult stature found in this population. Stature, biacromial diameter, and signs of sexual maturation were studied and comparisons were made with European samples. All of the variables showed that Chilean females reach puberty earlier than, and cease growth before Europeans, while males mature at the same pace as Europeans. It is concluded that the large sex dimorphism in adult stature found in this sample is mainly due to this earlier cessation of growth in Chilean females.

Adolescent↗