Quantitative interactions between Candida albicans and the mutans streptococci in patients with Down Syndrome.

BACKGROUND: Oral microorganisms produce damage through the transfer to bloodstream, colonizing other tissues or direct damage in the oral cavity. Aim to study the quantitative interactions between C. albicans and the mutans streptococci and ms serotypes in the saliva of the oral cavity of patients with Down syndrome (DS). MATERIAL AND METHODS: Included 120 patients of both genders, 60 patients with Down syndrome (DS) and 60 pa- tients as a control group (CG). Samples of saliva were taken, and bacteria and fungi were grown on TYCSB and Saboureaud agar. Microbiological, serological and quantitative analyses were performed to determine the kind of isolated of microorganisms corresponding to the ms c, e, f and k for species S. mutans and d and g for S. sobrinus and C. albicans. Electronic scanning microscopy was employed to visualize and confirm the colonies under study. Statistics analysis included t-test proofs for matched data test, Scheffé and ANOVA. RESULTS: Forming units (CFU) per mL of saliva of C. albicans a significant difference was observed among DS

The Chilean socio-ethno-genomic cline.

Studies of the current Chilean population performed using classical genetic markers have established that the Chilean population originated primarily from the admixture of European people, particularly Spaniards, and Amerindians. A socioeconomic-ethno-genetic cline was established soon after the conquest. Spaniards born in Spain or Chile occupied the highest Socioeconomic Strata, while Amerindians belonged to the lowest. The intermediate strata consisted of people with different degrees of ethnic admixture; the larger the European admixture, the higher the Socioeconomic Level. The present study of molecular genomic markers sought to calculate the percentage of Amerindian admixture and revealed a finer distribution of this cline, as well as differences between two Amerindian groups: Aymara and Mapuche. The use of two socioeconomic classifications - Class and Socioeconomic Level - reveals important differences. Furthermore, Self-reported Ethnicity (self-assignment to an ethnic group) and Self-reported Ancestry (self-recognition of Amerindian ancestors) show variations and differing relationships between socioeconomic classifications and genomic Amerindian Admixture. These data constitute a valuable input for the formulation of public healthcare policy and show that the notions of Ethnicity, Socioeconomic Strata and Class should always be a consideration in policy development.

Distribution of (CGG)n and FMR-1 associated microsatellite alleles in a normal Chilean population.

We report on the allele distribution in a normal Chilean population at 2 microsatellite loci neighbouring the FRAXA locus and at the CGG repeat in the 5' end of the FMR-1 gene, which causes the fragile X syndrome. The most common CGG repeat allele was 30 (41.7%), with 29 being second most common (30.2%). This distribution was similar from that seen in Caucasians but different from that observed in Chinese controls, where the most common allele was 29 repeats. Four alleles of FRAXAC1 and 6 of DXS548 were observed in the Chilean sample. A striking linkage disequilibrium of FMR-1 alleles with FRAXAC1 alleles was observed. In 90% of the 30 CGG repeat alleles only 31% of the 29 CGG repeat alleles had the FRAXAC1 154 bp allele. This result is in agreement with the suggestion that slippage between CGG repeat alleles 29 and 30 and between 152 and 154 FRAXAC1 alleles is very rare. This study suggests a founder chromosome effect in the Chilean population.

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.

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.

Malignant melanoma in Chile: an unusual distribution of primary sites in men from low socioeconomic strata.

BACKGROUND: Mortality from malignant melanoma (MM) has increased in Chile in the past decade. The location of MM lesions on the body has been correlated with prognosis and survival. AIM: To review body site and gender relationships with histopathologically confirmed primary MM in Chile. METHODS: Records of 575 cases presenting to 5 state hospitals from 1992 to 2001 were analysed. RESULTS: There were 360 women and 215 men. Women showed a significantly higher number of MM on the legs, cheeks and arms, and in the genital area, whereas men showed a significantly higher number on the ears, backs of the hands, soles and feet. Men had a predilection for MM with a poor prognosis. CONCLUSION: The different body site distribution of primary MM in men and women may be explained by a different pattern of sun exposure. Ethnic and genetic factors may also be involved. The predominant location of MM in women in Chile is similar to white populations, whereas the location in men is similar to that observed in black and Asian populations. These observations may be relevant to the high mortality of MM in Chilean men.

Misconceptions and false expectations in neutral evolution.

Neutral evolution results from random recurrent mutation and genetic drift. A small part of random evolution, that which is related to protein or DNA polymorphisms, is the subject of the Neutral Theory of Evolution. One of the foundations of this theory is the demonstration that the mutation rate (m) is equal to the substitution rate. Since both rates are independent of population size, they are independent of drift, which is dependent upon population size. Neutralists have erroneously equated the substitution rate with the fixation rate, despite the fact that they are antithetical conceptions. The neutralists then applied the random walk stochastic model to justify alleles or bases that were fixated or eliminated. In this model, once the allele or base frequencies reach the monomorphic states (values of 1.0 or 0.0), the absorbing barriers, they can no longer return to the polymorphic state. This operates in a pure mathematical model. If recurrent mutation occurs (as in biotic real systems) fixation and elimination are impossible. A population of bacteria in which m = 10(-8) base mutation (or substitution)/site/generation and the reproduction rate is 1000 cell cycle/year should replace all its genome bases in approximately 100,000 years. The expected situation for all sites is polymorphism for the four bases rather than monomorphism at 1.0 or 0.0 frequencies. If fixation and elimination of a base for more than 500,000 years are impossible, then most of the neutral theory is untenable. A new complete neutral model, which allows for recurrent substitutions, is proposed here based on recurrent mutation or substitution and drift alone. The model fits a binomial or Poisson distribution and not a geometric one, as does neutral theory.

[Psychosocial sexual phenotypes. A proposition and their ontogeny]. / Fenotipos sexuales psicosociales. Una proposición y su ontogenia.

A proposition of operational phenotypes and ontogeny for psychic and social sex is presented. These phenotypes are defined according to the three major theories of Biology: cell, inheritance and evolution. Sexuality is defined, for species, as the ability to produce individuals in creative genetical process by means of genetical recombination associated with reproduction. Sex is defined, for individuals, as the set of characters (phenotypes) that allow those gene recombinative and reproductive processes. The Psychic Sex includes: the Sexual configuration of identity, the Sexual appetizing configuration, the Genital connection, the Somatoerogenic connection, the Integration of psychic sex into personality and the Sexual psychomotor form. The Social sex includes those individual behaviors performed isolately or collectively that realize sexual processes in the species. The ontogeny of these phenotypes considers that they are the product of the interaction between the genotypes and environments. The endogenous neuroendocrine differentiation, mainly due to genetic factors., interacts with the familial and social environment, which presents a set of sexual polar semiotic factors. The endogenous differentiation makes more or less probable to acquire further sexual differentiations yielded by co-living (interactions that are brought about by living together) with that differentiator (that produces differentiation) polar environment.

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.

[A model for determination of the expected numbers of chromosome alterations and break points]. / Un modèle pour la détermination du nombre attendu de remaniements et de points de cassure chromosomique.

The assumption that the expected number of chromosome break points is simple and directly proportional to the length of chromosomes is criticized. Translocations and inversions imply two dependent break points in relation to their distribution on the whole karyotype, that is why, this assumption should be modified. A model is presented which takes the dependence into account and which provides the formulas for the calculations of probabilities of binary rearrangements and of their respectives break points. We apply the model to the human karyotype.

[Assessment of height as an indicator of population nutritional status]. / Evaluación de la estatura como indicador nutricional poblacional.

BACKGROUND: Chilean girls of middle and low socioeconomic levels are shorter than their European or North American counterparts. AIM: To challenge the hypothesis that undernutrition is the cause of the shorter stature of Chilean girls. MATERIAL AND METHODS: Height, weight, sexual maturation, biacromial and bi-iliac diameters of low and middle socioeconomic level Chilean children aged 0 to 20 years old, were compared with data from French, English and North American children in the same age range. RESULTS: Chilean girls had an earlier sexual maturation, had bigger biacromial and bi-iliac diameters and had a higher weight for height than European girls. Weight for height of these girls was over the values proposed by the Chilean Ministry of Health, that are based in NCHS/WHO tables. Chilean girls with recent European ancestry were taller than girls without this ancestry. Chilean boys were smaller and had lower weights than their foreign counterparts. Bi-iliac diameters were similar to those of French boys and sexual maturation was similar to English boys. CONCLUSIONS: These results indicate that genetics and not undernutrition is involved in the shorter height of Chilean girls, when compared with their European or North American counterparts.

Epistemic restrictions in population biology.

Biologists have believed that the application of statistical or mathematical models to population biology has always been a correct and helpful tool to acquire knowledge. The present article demonstrates that the standard interpretation of statistical results yielded by the application of mathematical models to some populational processes, not only hides knowledge, but may lead to wrong knowledge. These epistemic restrictions (type I and II errors). A new more versatile conditional interpretation of statistical results is proposed.

Non random DNA evolution.

A model for testing random molecular evolution is proposed. Randomness of recurrent mutation is defined based on isotropy and zero covariance among nucleotide sites. Assuming an equal rate of mutation for the bases A, T, G, and C, in both DNA strands, a mutational matrix of transformation A, T, G, and C with 6 parameters is developed. Under this model the equilibrium proportions (F) of the bases are FA = FT = (D + E)/[2(D + E + H + J)] and FG = FC = (H + J)/[2(D + E + H + J)], D, E, H, J being 4 of the 6 matrix parameters. Thus the expected (FA + FT)/(FG + FC) ratio can also be tested. If the average rate of mutation is 10(-8) per nucleotide site and cell replication, the equilibrium for every site, in most species, is reached in 10(8) years. Eight DNA segments from human, bacteria, fungus and insect genomes were chosen to test these proportions and their heterogeneity among coding and non coding subsegments. While FG was similar to FC as expected, FA was highly different from FT Huge heterogeneities were found between coding and non coding segments and among non coding segments. These results are a strong evidence for non randomness of molecular evolution.

[Confidence of 100 per cent sensitivity and specificity]. / Confiabilidad de la sensibilidad y especificidad del 100%.

A new strategy and four new methods are presented to calculate the limits of the confident interval for an estimate of a proportion equal to 1.0 or 0.0. A current formula which includes 1/(2n) for continuity correction leads to a confident interval which does not include the parameter estimate. Thus, it is proposed: 1) The exclusion of the factor 1/(2n) in that formula leads to correct most of its inconsistencies. The new strategy assumes that the upper limit of a confident interval when the estimates is 100%. The lower limit is calculated by assuming that there is a proportion in the population, from where the sample was taken, such as the probability of getting 100% in the sample is equal to the probability of falling into type I error of current statistics (0.05, 0.01, etc). Three methods are proposed with this strategy. 2) A combinatorial solution based in the knowledge of the number of individuals at whom the test can be applied. 3) A solution based on the binomial distribution. 4) A solution based on the Poisson distribution.

[Scientific ethics of the origin of humans]. / Etica científica del origen humano.

The analysis of the early human life from the view point of a scientific ethics is presented. Life is a historical materioenergetic process of specific organization. This phylo-ontogenetic process is a continuous process without interruption. Biology has demonstrated that human eggs or embryos are full human individuals, even though not all human conception is a human being. The contradictions involved in taking ethical decisions after knowing the percentage of conceptions obtained by in vitro or in fallopian tube fertilization that reach the birth are shown. The advantages of scientific ethics in the analysis of the origin of the different positions are indicated. These advantages come from the dissection of the different cognitive, affective-emotional and value attribution frames involved in the alternative decisions.

[Ontogenetic origin of the human individual from his genome]. / Comienzo ontogénico del individuo humano desde su genoma.

Diverse propositions about the ontogenetic origin of a live organism, specially human beings, are examined. Unambiguous and objective propositions about this origin are that a live organism is an ontogenetically programmed and integrated organisation, that the origin condition has the greater influence on other processes, that in pluricellular organisms, no organ or tissue can be considered critical to establish origins and that the origin must be established by endogenous elements. Several hypotheses about the origin of life are discarded. The integration between oocyte cytoplasm and the genetic material that it receives, that culminates in the first genome replication, is proposed as the process that gives origin to the individual. This process occurs in all living organisms.

[Scientific ethics and frozen embryos]. / Etica científica y embriones congelados.

BACKGROUND: Scientific Ethics is the theory and praxis of decisions. Philosophical Ethics is presented as the theory and praxis of the good. As the good differs among cultures, Philosophical Ethics is dependent on the endo-cultural good conception. The decision (included that one of adhesion or not to a world vision) depends on neuro-psychic specific factors: i) cognitive factors that include mostly the knowledge of the alternatives and their consequences and the ideological or religious conception of good in relation to the alternatives; ii) affective factors that make alternatives pleasant, unpleasant or neutral, attractive, repulsive or neutral; iii) emotional factors that associate to alternatives anger, peace or neutrality, sadness, happiness or neutrality; iv) value factors that assign importance, triviality or neutrality to alternatives, or assign them significance, irrelevancy or neutrality. There are unspecific factors such as the psychic energy, desire or others. Mixed factors such as attitude, motivation, intention and others. Scientific Ethics deals with the mind as a materio-energetic process which is different from the soul, eggs and embryos of any species are full individuals of that species, because, they have initiated a copy of their genome that specify, give autonomy and define them as individuals. For Scientific Ethics to leave frozen embryos like that for ever, to defrost and get rid of them or to use their cells for science are synonymous of killing them. To defrost them to use their cells as stem cells for somatic cell therapy or to implant them into uteri to continue their development is to maintain alive their cells, but only the implantation allows their maintenance as individuals, thus, being the only compatible with the Christian ethics. The compatibility of these alternatives with other ethics is discussed.

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.

[Study of the Widal test phenotypic expression of blood groups ABO, Rh and MNSs in patients with typhoid fever]. / Estudio de la reaccion de Widal como expression fenotipica for medio de los sistemas sanguineos ABO, Rh y MNSs.

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.

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.