Carlos Y Valenzuela

Socioeconomic assortative mating in Santiago, Chile: A demonstration using stochastic matrices of mother‐child relationships applied to ABO blood groups

Abstract The gene and phenotype frequencies for the ABO blood groups system were studied in two socioeconomically different subpopulations of Santiago, Chile. The data were taken from the maternity services and blood banks of two hospitals, one serving mainly low socioeconomic classes and the other serving middle and high socioeconomic groups. Results show a clear difference in gene and phenotype frequencies between the two subpopulations, a difference maintained in two generations (mothers and their children). These results reinforce other studies showing that socioeconomic forces have resulted in assortative mating and different genetic subpopulations in Chile.

The sequence of eruption of the permanent dentition in a Chilean sample with Down's syndrome

The eruption of the permanent teeth in Downs individuals is reportedly delayed. The extent of such delay in comparison to normal children has been little studied. The eruption characteristics of the permanent teeth in a sample of Chilean individuals with Downs syndrome were here compared with those of the normal Chilean population. The sample consisted of 240 Downs individuals (all with trisomy 21), 116 males and 124 females. The chronological sequence of eruption in Downs children was not completely different from the normal. The least affected teeth were upper and lower first molars and central and lateral incisors. Alterations of the eruption sequence were not necessarily a consequence of alterations in the time of eruption. Asymmetries between sides of the jaw were mainly in canines and premolars. Alterations in sequence timing and asymmetry seem to be age dependent, being less frequent between 7 and 9 yr of age and more frequent between 10 and 14 yr of age. This may also reflect the larger variances of age of eruption observed in Downs individuals. Despite this, Downs children maintained a certain similarity in sequence and symmetry in comparison to normals.

Interleukin-1 gene cluster polymorphisms associated with periodontal disease in type 2 diabetes.

BACKGROUND Epidemiologic studies have shown an increased frequency, severity, and risk of periodontitis in patients with diabetes. Periodontitis is associated with certain interleukin (IL)-1 gene cluster polymorphisms. Diabetes is a proinflammatory state with increased levels of circulating cytokines suggesting a causal role for inflammation in its etiology. Common genetic factors may be involved in the susceptibility for diabetes and periodontitis. We evaluated the relationships among IL-1 gene polymorphisms, type 2 diabetes, and periodontitis. METHODS One hundred twelve patients with diabetes and chronic periodontitis, 224 patients without diabetes but with chronic periodontitis, and 208 healthy subjects without periodontitis were studied. All received a clinical periodontal examination and assessment of standard periodontal parameters. IL-1A -889, -1B +3954, and -1B -511 polymorphisms were identified by polymerase chain reaction (PCR) amplification followed by restriction enzyme digestion and gel electrophoresis. Variable numbers of IL-1RN tandem repeats were detected by PCR amplification and fragment-size analysis. RESULTS The severity and extent of periodontitis was significantly greater in patients with diabetes than in patients without diabetes. No significant differences in IL-1A -899, -1B +3954, or -1RN genotype frequencies were found between patients with diabetes and patients without diabetes. The IL-1A -889 TT genotype (odds ratio [OR] = 2.90; 95% confidence interval [CI] = 1.20 to 7.02), IL-1B +3954 TT genotype (OR = 3.54; 95% CI = 1.15 to 10.85), and IL-1B -511 CC genotype (OR = 2.10; 95% CI = 1.25 to 3.58) were significantly associated with periodontitis. The presence of an IL-1 positive genotype was significantly associated with periodontitis (OR = 1.61; 95% CI = 1.04 to 2.49). No interaction between smoking status and polymorphisms was found. CONCLUSIONS Periodontitis was significantly associated with some IL-1 gene polymorphisms. No association between diabetes and IL-1A and -1B gene polymorphisms was found.

Sexual dimorphism in number and proportion of neurons in the human median raphe nucleus

The number and proportion of neurons in the median raphe nuclei stained by the Golgy-Cox and Nissl methods was compared in males and females infants. When subjects are matched by age and cause of death the number and proportion of fusiform, ovoid and multipolar cells differs significantly between sexes at different ages.

Dendritic morphology and orientation of pyramidal cells of the neocortex in two groups of early postnatal undernourished-rehabilitated rats.

Postnatal undernutrition in animals and in humans leads to significant reduction in basal dendritic arborization of layer Vth pyramidal cells of the neocortex. Under the hypothesis that there are critical developmental periods for undernutrition to produce alterations in dendritic differentiation, we studied apical dendritic morphology and orientation of pyramidal cells from the deeper layers of the neocortex in rats undernourished until day 10 (UP10), until weaning (UP21) and in a control group (C). Neurons were stained by the Golgi-Cox method. The main findings are: (i) an increased number of atypically oriented pyramids with apical dendrites extremely short in (UP10) and (UP21) groups and, (ii) the presence of classical pyramids with significantly longer apical dendrites in layers V and VI in (UP10) and (UP21) groups than in the control group (C). We believe that undernutrition may disturb critically the early postnatal brain development by altering intrinsic factors and extracellular molecular signals that guide and regulate the apical dendritic growth of neocortex large pyramidal cells.

Sex dimorphism in adult stature in four Chilean populations

The sex dimorphism for adult stature is compared in four Chilean populations which differ in their Amerindian ABO blood group composition. Statistical analysis revealed a significant association between sex dimorphism and Amerindian admixture in these populations. Assuming, on one hand, that sex chromosomes have an influence on adult stature and human growth and considering, on the other, that the four populations differ in their X and Y chromosome composition as a consequence of an asymmetrical inter-racial marriage practice, it is postulated that the observed association between sex dimorphism and Amerindian gene composition is a result of this peculiar mating structure.

Human Raphe Magnus Nucleus: a morphometric Golgi-Cox study with emphasis on sex differences.

The number and proportion of neurons according to their type and size in the Raphe Magnus Nucleus stained by the Golgi-Cox and Nissl methods were compared in male and female infants. Four female/male pairs aged from 2 to 150 days were studied. While females showed more neurons than males, males showed a higher proportion of large multipolar (more than 40 microm) and fusiform neurons (more than 20 microm) but not of ovoid neurons (more than 15 microm). These differences varied according to the type of cells and age of infants. Some of these results are similar to those found in the human Median Raphe Nucleus with the same methods.

Month at menarche : a re-evaluation of the seasonal hypothesis

The hypothesis of a dominant or major seasonal factor that produces the winter peak of menarche found in European girls was tested using several Caucasian and Mongolian samples from the northern hemisphere and two Chilean samples. Present results do not support such a hypothesis. The month at menarche of Chilean girls did not show the expected winter peak; February, a winter month in Europe, showed a deep trough in most samples. Instead, several Mongolian and Caucasian samples from the northern hemisphere clustered according to their ethnic origin rather than to the expected northern hemisphere yearly distribution of photoperiods and temperatures. Other non-seasonal factors seem to explain much better the periodicity of the monthly incidence of menarche. A phylogenetic factor (imprinting) is proposed to explain peaks seen in December and January for Caucasian, Mongolian, Finnish and Chilean samples living in the northern and southern hemispheres. Ontogenetic factors are proposed to explain the highly significant coincidence between the month of menarche and the month of birth, and the modulation of the phylogenetic imprinting by months at which gestation occurred in relation to menarche. The Finnish and Chilean samples, which can be considered mixed Caucasian and Mongolian, showed an intermediate pattern between the Caucasian and Mongolian groups.

ABO, Rh, MNSs, Sex and Typhoid Fever

A case-control study on the association between genetic markers (ABO, Rh, MNSs and sex) and typhoid fever (TF) was performed. We found that (a) the B allele conferred protection to females for TF and a mild susceptibility to males; (b) the CDe haplotype (or the RH3 phenotype, mostly CDe/CDe) was associated with protection against Salmonella in both sexes, while cDE (or RH7, mostly cDE/cDE, and RH8, mostly cDE/cde) was associated with susceptibility to TF, and (c) heterozygotes Ss (MNSs system) had a high susceptibility, while SS and particularly ss homozygotes seemed to be protected for the disease. There were very significant interactions among the blood systems and sex.

Dimorfismo sexual en la pigmentación de la piel, color de ojos y pelo y presencia de pecas en adolescentes chilenos en dos estratos socioeconómicos

BACKGROUND The risk of skin cancer is correlated with skin colour. Pigmentation protects against the effects of UV radiation. AIM To study skin, eyes and hair colour in Chilean teenagers. MATERIAL AND METHODS The constitutive skin, hair and eyes colour and the presence of freckles was studied in 716 teenagers (416 females) of a low socio economical level and in 307 teenagers (155 females) of a high socio economical level. RESULTS The proportion of foreign surnames was higher in the high stratum and we only found aboriginal surnames in the low stratum. The females of the lower stratum presented lighter skin than males. This difference was not observed in the higher stratum. We did not find significant differences in the eye colour between sexes, however, adolescents from the high stratum presented lighter eye colour. Females had lighter hair colour than males in both strata, also, we found lighter hair colour in the high stratum. We did not find significant differences in the presence of freckles between strata, but, the proportion of females with freckles was higher than that of males in both strata. CONCLUSIONS Our results may identify different groups of people, within the Chilean population, with different susceptibility to the effects of ultraviolet radiation.