Biomedical subjects

O Pavlovsky

Publications and source records attributed to O Pavlovsky.

At least 19 recordsLinked to original sources

PubMed2000

Evidence of major gene control of cortical bone loss in humans.

Cortical index (CI) is the ratio of the combined cortical thickness to the total diameter of the bone. It serves for the assessment of the geometric properties of bone and for indirect evaluation of bone mass. CI is a useful predictor of osteoporosis. The aim of the present study was to test the hypothesis of major gene control of CI variation in a large sample of pedigrees from Chuvashia, Russia. Complex segregation analysis revealed that the major gene model of CI inheritance is the best fitting and most parsimonious for the present data. Parameters of the genotype-gender specific dependence of CI variation on age were estimated simultaneously with other parameters in the segregation analysis. The results of analysis showed that not only the baseline level of CI but also the age at onset of the involutive bone changes (inflection point) and the rate of the CI decrease with age (slope coefficient) are under control of the same major gene. Non-major gene effects shared by pedigree members (residual familial correlations) were found to be statistically insignificant. Approximately 73% of inter-individual variation in CI was attributable to the effects explicitly included in the model.

Adolescent↗

PubMed2000

Use of the hand bones roentgenographs in the prediction of age in nine human populations.

The major aim of this study was to develop an accurate method of age prediction for a wide range of ages, based on the roentgenographic assessment of the hand bones, for use in paleoanthropology and forensic medicine. The roentgenographs of the hand bones were assessed in 5756 individuals, 2683 males and 3073 females, aged 17-93 and 17-89, respectively, belonging to 9 ethnic groups from the former USSR, Israel, and Sinai peninsula (Egypt). For each roentgenogram an equidistant osteographic score (OSS) including the descriptive criteria of bone age, such as (1) osteophytes or nodes of Heberden in the periarticular regions and at sites of tendon attachment, (2) manifestations of osteoporosis, (3) signs of sclerosis, and (4) non-traumatic articular deformities, was estimated. Regression analysis, that included linear, non-linear, logistic, and stochastic models, was used to evaluate the relationships between age and OSS. This relationship was best described by a logistic regression function. Results of the logistic regression analysis clearly indicate that OSS is a strong predictor of an individual's age, with r2 values ranging from 0.671 to 0.901 (p < 0.001). Our standard errors of estimate were ranging from +/- 4.2 to +/- 7.3 years, comparing favorably with most known methods of bone age assessment. This study provides an efficient method of age prediction, which allows to extend the upper limit of prediction to the age of 70 years with acceptable accuracy.

Adolescent↗

PubMed1999

Segregation analysis reveals a major gene effect in compact and cancellous bone mineral density in 2 populations.

Involvement of genetic factors in determining bone mineral density (BMD) is doubtless. However, the exact nature of the genes governing BMD variation and sources for genetic determination of BMD of different parts of bone (compact and cancellous) have not been completely studied. The results of the complex segregation analyses performed in our previous study (Livshits et al. 1996) on a Turkmenian sample strongly support the hypothesis that a single Mendelian locus has a large effect on BMD. The parameter estimates for both types of bone tissue were so similar that we could assume a common gene effect for BMD variation of cancellous and compact bone. The objectives of the present study are to test again the possibility of major gene control of BMD in a different ethnic sample of pedigrees, namely, the Chuvasha. In addition, we report here the results of a bivariate segregation analysis of compact and cancellous BMD performed in both the Turkemenian and the Chuvasha samples of pedigrees. The results of the present study closely resemble the results obtained on the Turkmenian pedigrees. Likewise, the major finding of the present study is that there is a significant major gene effect on both compact and cancellous BMD; polygenic hypotheses were clearly rejected. Moreover, the results of the bivariate segregation analysis in both the Chuvasha and Turkmenian samples were similar. They lead to acceptance of the hypothesis that there is a single major locus with pleiotropy to both compact and cancellous bone.

Adolescent↗

PubMed1996

Population biology of human aging: segregation analysis of bone age characteristics.

The main goal of the present study is to elucidate the extent to which primary characteristics of bone aging are determined by major gene effects. We report the results of a complex segregation analysis of bone mineral density (BMD) and osseographic score (OS) carried out on an array of pedigrees from rural Turkmenia. Both variables showed a significant correlation with age and thus were adjusted. However, the correlations with body height, weight, body mass index, and obesity indexes were negligible. The results of the segregation analysis performed on BMD clearly indicate major gene effects on BMD variation. The Mendelian transmissibility hypothesis with two codominant alleles was chosen as the best-fitting and most parsimonious model. Under this hypothesis 50-60% of total variation in BMD, depending on bone area, can be attributed to a major gene effect, and the frequency of the allele determining the higher value of bone density is between 30% and 38% in the Turkmenian population. Regarding the OS, segregation analysis provided evidence supporting intergenerational transmissibility of this characteristic and yet the Mendelian model was rejected.

Adolescent↗

PubMed1996

Population biology of human aging: ethnic and climatic variation of bone age scores.

Hand radiograms for osseographic assessment of bone-aging status were taken from more than 7500 individuals living in 32 different geographic localities and belonging to 20 ethnic groups. Multiple regression analysis was used to evaluate possible associations between bone-aging parameters and number of climatic factors. To determine whether population differences in bone-aging estimates were related to linguistic, ethnic, or genetic differences among the samples, we performed a matrix correspondence analysis. Euclidean distance matrices for parameters TM (average age at entering visual stage of bone aging) and B (the rate of bone aging per year) were tested against design matrices specifying linguistic or ethnic affiliation of the tested populations, yet no significant correlations were detected in this set of analyses. The matrix of joint genetic distances based on 10 genetic systems showed significant correlation (r = 0.48, p = 0.013) with the matrix of B differences. This suggests some genetic control in the rate of bone aging. TM and age-adjusted bone-aging scores (Z) yielded no evidence of correlation with genetic differences among the studied populations. Multiple regression analysis, however, uncovered that 37.5% of TM variation and 48% of Z variation could be explained by climate factors and their interactions.

Age Determination by Skeleton↗

PubMed1995

Population biology of human aging: methods of assessment and sex variation.

Biological age, as assessed by osteographic measurements of hand bones from radiograms, was estimated in about 7000 individuals belonging to 32 ethnic groups and samples and to 2 major human groups (Europeans and Asians). Individual ages in the total group varied between 16 and 99 years old. Our biological age measure is strongly correlated with chronological age of the individual (Pearson's r = 0.78-0.80, p < 0.001), which renders the correlation amenable to fitting with a two-stage stochastic model. The following parameters of the model were estimated accordingly: t0 is the minimal age at which initial bone changes occurred, q is the probability that an individual will first develop involutive bone change at age ti > t0, and B is the rate of aging (bone change) per unit time. The parameters varied considerably within different populations, but only a few samples showed statistically significant sex differences for all three parameters. However, B was consistently higher among women than among men. Apart from that, the distributions of the observed biological age estimates adjusted on the expected biological age values reveal no differences between men and women in any of the studied samples or in the total population.

Adolescent↗

PubMed1975

Distribution among the chromosomes of Drosophila pseudoobscura of the genes governing the response to light.

Most strains of Drosophila pseudoobscura are neutral to light when tested in phototactic mazes. However, clear-cut photopositive and photogenative populations are obtained by selection over a series of generations. The genetic nature of the differences between the positive and negative populations has been studied in crosses in which the three large autosomes carried mutant markers. All chromosomes contain genes which influence the response to light. The third chromosome has the strongest effect, followed by the second, the X, and the fourth chromosomes. This seriation is not in proportion to the relative lengths of the chromosomes. Either the effective genes are not very numerous, or some of them exert stronger influences than others.

Animals↗

PubMed1974

Behavior in different environments of populations of Drosophila, pseudoobscura selected for phototaxis and geotaxis.

When tested in Hirsch-Hadler mazes, Drosophila pseudoobscura descended from natural populations is phototactically and geotactically neutral on the average. Decidedly positive and negative populations have been obtained by artificial selection. The behavior is independent of temperature (15-27 degrees ) and age (2-17 days). The flies perceive light as weak as 0.2 lux; from 7 to 3000 lux the behavior difference between positive and negative strains increases little, and perhaps decreases at 8000 lux. A remarkable transformation occurs with red light; the population that is negatively phototactic with shorter wave lengths or with white light becomes photopositive.

Age Factors↗

PubMed1973