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Biomedical subjects

K Sharma

Publications and source records attributed to K Sharma.

At least 199 records · Page 11Linked to original sources
PubMed1985

Within- and between-zygosity variance in oral traits among US and Punjabi twins.

Cross-cultural comparison of twin variances reveals widespread heterogeneity among zygosities for dental occlusal traits, implying various biases in calculation of genetic variance or heritability estimates. These estimates are fairly robust for dental size traits, however. Differences in pattern between Punjabi (Northwest Indian) and American twins highlight the environmental differences that affect heritability determinations.

Dental Occlusion↗
PubMed1985

Genetic variance in dental dimensions of Punjabi twins.

Genetic variance analysis of 56 tooth size traits was based on a sample of 58 pairs of twins (23 MZ and 35 DZ) from Chandigarh, India. Results of a t-test for equality of means showed no association of zygosity with any of the traits. Heterogeneity of total variance was found in 18 traits, which invalidates conventional genetic variance estimates and reveals considerable hidden environmental determinance. In contrast to other studies, Indian MZ twins had higher variance than did DZ twins, in most instances. There was also evidence of stronger environmental covariance for MZ and DZ twins. The study revealed substantial, complex environmental determination for some dental dimensions, especially of incisors and second molars.

Adolescent↗
PubMed1984

A family study of anthropometric traits in a Punjabi community: I. Introduction and familial correlations.

Data on 40 anthropometric measurements from 144 nuclear families in Chandigarh, India, are presented. Most families contain a pair of monozygotic or dizygotic twins, one or more singleton siblings, and their parents. Familial correlations for age-sex standardized, normalized measurements are estimated by maximum likelihood for marital, parent-child, sibling, and twin pairs. Heterogeneity tests for sex-specific subtype correlations male-male, male-female, female-female) indicate that the sex of the relative plays no significant role in the magnitude of the familial correlations except for maternal effects and differences among male and female twin pairs for a few of the variables. Marital correlations are high for body measurements, but not for head or face variables. Twin correlations seem to indicate a higher level of heritability than correlations from other family members.

Adolescent↗
PubMed1984

A family study of anthropometric traits in a Punjabi community: II. An investigation of familial transmission.

Path analysis is used to characterize family resemblance for anthropometrics in twins and nuclear families from the Punjabi population of India. Significant positive assortative mating exists with respect to many body measurements, but not for cranial or facial variables. Evidence of a maternal effect for five measurements of bone diameter is reported. Twin resemblance is increased by a component not found in other pairs of relatives for all variables except nasal height, facial length, ear length, and head breadth. Although all variables have significant transmissible components, many have parameter estimates which are not consistent with strictly polygenic inheritance. Some form of cultural transmission is implicated for such variables, especially for those related to fatness levels.

Adolescent↗
PubMed1984

Estimates of genetic variance for some selected morphometric characters: a twin study.

Results on genetic variability in some of the morphometric characters on head and face, body girths and skin folds, based on 45 MZ and 67 like-sex DZ twin pairs, are presented. The data were subjected to a method which eliminated possible biases in the estimated genetic variances that could result from heterogeneity of total variances between zygosities of the 17 head and face measurements, heterogeneity was observed for only bizygomatic diameter. Head breadth means differed between MZ and DZ twins, indicating bias in the trait's genetic variance analysis. The results indicated a significant genetic component in these morphometric traits. For 11 girth and skinfold measurements, the t'-test based on hierarchical structure of twin data, also failed to reveal any appreciable difference between the mean values of MZ and DZ twins. Heterogeneity of total variance between zygosities was observed for three skinfold measurements, ie, biceps, triceps and suprailiac. The girth measurements, however, did not reveal any heterogeneity of total variances between the zygosities. The estimates of genetic variance revealed stronger genetic component for the girths than for the skinfolds.

Anthropometry↗
PubMed1984

Commingling in the distributions of fat-related measures in Punjabi families.

The distribution of anthropometric measurements related to fatness levels is examined to determine if skewness alone accounts for the nonnormality of such measures. A mixture of two normal distributions or a single skewed distribution fit the data significantly better than a single normal in all cases. For maximum hip width, knee diameter, and weight, two skewed distributions give a better fit than one skewed distribution, rejecting the null hypothesis of a single distribution even when skewness is considered. There is evidence for three skewed component distributions for biceps skinfold. Abdomen circumference, upper arm circumference, triceps skinfold, and calf skinfold are best approximated by a one component log-normal distribution. Children and parents show slightly different patterns in skewness and kurtosis when considered separately, but differences between them do not account for the commingling found in the combined distributions.

Adipose Tissue↗
PubMed1980

Mercury induced haematological and biochemical anomalies in Ophiocephalus (Channa) punctatus.

The effect of LC50 (1.8 mg/l) and a sublethal (0.3 mg/l) concentration of mercuric chloride on the blood of a teleost fish, Ophiocephalus (Channa) punctatus (the freshwater murrel-soley) was observed at 96 h and 15 and 30 days. Haemoglobin and haematocrit decreased after exposure, but no marked alteration was observed in total plasma protein. Glucose, cholesterol, urea, sodium, chloride, calcium and phosphate increased after acute and chronic exposures. Glutamic-oxalacetic transaminase, glutamic-pyruvic transaminase and amylase activities increased after exposure to LC50 for 96 h and to the sublethal concentration for 15 and 30 days. No marked alteration was observed in acid phosphatase activity. Alkaline phosphatase activity decreased in acute exposure, and increased in chronic exposure. Cholinesterase activity decreased after both acute and chronic exposures.

Animals↗