Search PubMed⌕ Search

Biomedical subjects

C F Sing

Publications and source records attributed to C F Sing.

At least 127 records · Page 7Linked to original sources
PubMed1981

HLA profile and Reiter's syndrome.

The analysis of the clinical and HLA profiles of 99 patients with Reiter's syndrome is reported. Antigen HLA-B27, which has previously been firmly associated with Reiter's syndrome, predisposes patients to develop disease features which reflect articular involvement. The HLA haplotype A2, B27 was found to be at an elevated frequency in our Reiter's syndrome sample, and the latter two antigens are also associated with a general increase in disease severity. Conversely, antigen BW35 appears to be protective against certain features of the syndrome. Patients with certain antigenic profiles (namely A2 and A3 together with B27) tend to develop certain syndrome manifestations earlier in the course of the disease than those with other antigens.

Arthritis, Reactive↗
PubMed1980

Genetic control of glycolysis in human erythrocytes.

We have studied heritability of the concentration of each glycolytic intermediate and adenine nucleotide in the cytosol of human erythrocytes obtained from a random sample of apparently healthy young individuals. Preliminary to analysis of heritability, each trait was statistically described and the effects attributable to variation in measured concomitants were removed by regression. Heritability was estimated using the family-set method. This method removes covariances between the index case, sibling and first cousin, due to those environmental determinants of the phenotypic values that are shared with a matched, unrelated control member of the family set. It also removes covariances due to environments that are shared by siblings and first cousins. Heritability was estimated by employing the fact that the variance of differences between first cousins minus the variance of differences between full siblings estimates three-fourths of the additive genetic variance. The heritability estimates for G6Pdagger, F6P, ATP and some other metabolite concentrations are high and significantly greater than zero. The heritabilities of G6P and F6P are likely attributable to genetic variation in the in vivo activity of HK and/or PFK, because the concentrations of these metabolites are tightly controlled by the two regulatory enzymes. Statistically significant heritability estimates for HK and PFK mass action ratios strongly suggest genes are responsible for a portion of the quantitative variation in these enzyme activities. Since HK and PFK regulate glycolysis and the production of ATP, genetic variation in their activities might be causally related to the heritability of ATP concentration.

Adolescent↗
PubMed1979

Familial aggregation of blood pressure and weight in adoptive families. I. Comparisons of blood pressure and weight statistics among families with adopted, natural, or both natural and adopted children.

Tests of homogeneity of means, variances and correlations for systolic blood pressure (BP), diastolic BP and weight among subdivisions of a smple of adoptive families are presented. The means and variances of either type of BP, but not weight, were not significantly heterogeneous among families grouped according to the number of parents and children, natural and/or adopted, in the family unit. Estimates of correlation between family members wree not heterogeneous among subdivisions for each of the three variables. Our results indicate that these data are suitable for a genetic analysis of familial aggregation. Pooled correlations suggest that the degree of resemblance of BP and of weight between family members varies within and across generations. Correlations involving the adoptees were significantly different from zero only for diastolic BP.

Adolescent↗
PubMed1979

Familial aggregation of blood pressure and weight in adoptive families. II. Estimation of the relative contributions of genetic and common environmental factors to blood pressure correlations between family members.

An analysis of the familial aggregation of blood pressure (BP) was conducted to provide estimates of the role of genes and household environment in determining the phenotypic resemblance between biologically related family members. The biological model used for this analysis parameterizes the correlations between family members into the contributions of genetic and environmental variability shared within and across generations. Hypothesis testing about different parameters in the model suggests that shared environment explains larger fractions of the parent-natural child and the full sib correlations for diastolic BP than for systolic BP. For diastolic BP, children in a household share the effects of common environment in addition to the effects which they share with their parents. Dependence of the degree of resemblance between household members on the effects of environmental factors shared within and a-ross generations is not explained by the variability of length of cohabitation among individuals.

Adolescent↗
PubMed1979

H-2 and non-H-2 determined strain variation in palatal shelf and tongue adenosine 3':5' cyclic monophosphate: a possible role in the etiology of steroid-induced cleft palate.

The concentration of cAMP was measured in palatal shelves and tongues of 14.5-day old foetuses, 14.5-day old foetuses from steroid treated mothers, and 15.5-day old foetuses from four inbred lines of mice which represent the four possible combinations of two H-2 alleles and two residual genetic backgrounds. The incidence of spontaneous and steroid-induced cleft palate in these four strains was also determined. Analyses of variance of the cAMP data reveal that both the H-2 region and residual genetic background determine cAMP concentrations in both tissues and on both days of development. Similar analyses of cAMP concentrations after steroid treatments of the mother indicate that the interaction between H-2 and residual genetic background is significantly different in the injected than in the uninjected mice in both palatal shelves and tongues. The incidence of steroid-induced cleft palate parallels the palatal shelf concentration of cAMP before steroid treatment of the mother with one exception. These data suggest that a portion of the H-2 controlled component of susceptibility to steroid-induced cleft palate is mediated through alterations in the metabolism of cAMP.

Animals↗
PubMed1977

A path analysis of the causal relationships between red cell glycolytic intermediates, ADP and ATP in sickle cell anemia.

The statistical relationships among the glycolytic intermediates (GI)) of the Embden-Meyerhof pathway, adenine nucleotides (ANs) and various hematological measures were estimated for 34 sickle cell anemia patients. Heterogeneity in linear and quadratic regressions of hemoglobin and hematocrit, both singly and jointly, on the GI and AN variables implied 1) that any single formula to standardize optical density measures of the GIs and ANs on a per gram hemoglobin or per liter cell water basis would not uniformly remove hemoglobin and hematocrit effects: 2) that ignoring significant hematological effects could bias the estimates of correlation among GIs and ANs; and 3) that hemoglobin and hematocrit measures do not reflect the same source of variability. The correlations among the GIs and ANs, after adjustment for hematological variability, were analyzed by path analysis to determine which of five proposed path models for cause and effect relationships were compatible with the data. AMP had a greater influence on ADP (coefficient of determination (CD) = 23%) than all the GIs together, while G6P and ADP influenced ATP variability the most (CD = 33% and 12%). The contributions of unknown factors to ADP and ATP variability were large for all models (CD = 56--77%) possibly due to stress of sickle cell disease. The path model with AMP and the four GIs (G6P, F6P, FDP, DHAP) influencing ADP variation, and the same GIs and ADP influencing ATP was the model most compatible with the data.

Adenine Nucleotides↗
PubMed1976

The population genetics of parthenogenetic strains of Drosophila mercatorium. II The capacity for parthenogenesis in a natural, bisexual population.

Drosophila mercatorum is a bisexual species, but certain strains are capable of parthenogenetic reproduction in the laboratory. We investigated the parthenogenetic capacity of the virgin daughters of females captured from a natural, bisexual population in Hawaii. An isozyme survey indicated the natural population is polymorphic at about 50% of its loci, and its individuals heterozygous at 18% of their loci. The predominant mode of parthogenesis in D. mercatorum causes homozygosity for all loci in a single generation. Despite this radical change in genetic state, 23% of the virgin female lines produced adult parthenogenetic progeny, and 16% produced parthenogenetic progeny themselves capable of parthenogenetic reproduction. The parthenogenetic rats as measured by the number of parthenogenetic progeny themselves capable of parthenogenesis divided by the number of eggs laid is arougn 10(-5) for the virgin female lines. We argue that one of the major reasons for this low rate is that very few of the impaternate zygotes have a genotype that can survive and reproduce under the genetic conditions imposed by parthenogenetic reproduction. This intense selective bottleneck can be passed in a single generation if enough unfertilized eggs are laid, and once passed is accompanied by a large (perhaps a thousandfold) increase in the rate of parthenogenesis and by modifications in many phenotypic traits such as morphology and behavior.

Animals↗
PubMed1976

The effect of sample attrition on the frequency distribution of blood pressure and genetic marker phenotypes representing a natural unselected community: Tecumseh, Michigan.

High significant differences in mean age, blood pressure and phenotype frequency distributions between the non-migrants and "emigrants" of a total unselected community sample were discovered. Use of the mean of BP scores collected from epidemiologic surveys over a period of time as an individual score allows sample attrition to produce both a genetically and demographically biased sample of a population intended to represent an unselected community of people. Multiple regression analyses estimated the contribution of an individual's age, genotype and mobility out of the sample to predicting blood pressure variation. Variation in blood pressure means among certain marker phenotype classes was greater in those who leave than in those who stay, but only the upper portion of the pressure distribution contributed to this relationship. A genetic-environment interaction is suggested.

Female↗
PubMed1976

The unit of selection in Drosophila mercatorum. I. The interation of selection and meiosis in parthenogenetic strains.

An important problem in population genetics is the determination of the level of genetic organization to which fitness measures can be ascribed that yield an adequate description or prediction of the outcome of selection in populations. To study this problem, we used two strains of Drosophila merca torum (S-1-Im and O-3-Im) that are capable of both sexual and parthenogenetic reproduction, a feature that allows us to experimentally control many factors which affect genetic variability. Both S and O reproduce parthenogenetically by "pronuclear duplication," a mechanism that retains normal meiosis (and hence crossing over and assortment) but results in homozygosity for all loci in a single generation. Since an isozyme survey indicated that S and O differ at a third of their loci, we hypothesized that S and O have adapted in genetically distinct fashions to the genetic environment of total homozygosity. This is tested by breeding females that are S-O hybrids for 100%, 60% and 40% of their genetic backgrounds, and scoring their respective pathenogenetic progenies for four isozyme and two visible markers. The data collected gave evidence for a coadaptation to total homozygosity involving non-additive and non-multiplicative interactions between non-alleles. As the perturbation of the parental coadapted genotypes by meiosis increases (i.e., the greater the degree of S-O hybridity), the level of genetic material which behaves as an additive/multiplicative fitness unit becomes larger. Selective neutrality of genetic variation may be an artifact of our failure to measure the proper genetic unit of selection.

Animals↗