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Biomedical subjects

G L Ghai

Publications and source records attributed to G L Ghai.

8 recordsLinked to original sources

Arsenic dose in patients with cutaneous carcinomata and hepatic hemangio-endothelioma after environmental and occupational exposure.

A total of 16 male cases with malignant tumours associated with arsenic-polluted water were observed in Tarapacá and Antofagasta Provinces, northern Chile. Fifteen of them had skin carcinomata and the remaining one a hemangio-endothelioma of liver. The skin cancer cases had latent periods ranging from 12-45 years. Three patients were studied in detail. The first one (skin cancer) had a latent period of 20 years with a weighted mean dose of 1.2 mg/day (total dose for latent period 8.4 g). The second one (skin cancer) had a latent period of 23 years with a weighted mean dose of 1.0 mg/day (total dose for latent period 8.3 g). The third case (liver tumour) exhibited a latent period of 14 years with a weighted mean of 0.6 mg/day (total dose for latent period 3.1 g). Fifteen of the 16 cancer patients were labourers. For normal subjects of different ages and both sexes (n = 290) and ingesting arsenic-polluted water (0.60 ppm), the relationship between mean age and mean arsenic dose is expressed by a weighted least square polynomial regression, of second degree: E(y)- beta 0 + beta 1t + beta 2 t2 where y is mean arsenic dose (mg/person/day) and t is mean age (years). For the general male population and for male labourers, the respective equations are presented.

Adult

Mathematical model of mean age, mean arsenic dietary dose and age-specific prevalence rate from endemic chronic arsenic poisoning: a human toxicology study.

The aim of this investigation was to develop a mathematical model of mean age, mean arsenic dietary dose, and age-specific prevalence rate for endemic chronic arsenic poisoning. Data on mean age (years), mean arsenic dietary dose (mg/kg body weight/day), and age-specific prevalence rate per 100,000 population for endemic chronic arsenic poisoning in Antofagasta Commune, northern Chile, for the 1968-1971 period, were collected. Endemic chronic arsenic poisoning means here chronic arsenical dermatosis associated with marked or sever symptoms (or signs) of chronic arsenic poisoning (chronic diarrhoea, hepatic cirrohsis, chronic bronchitis, bronchiectasis, recurrent broncho-pneumonia, cardiomegaly, systemic occlusive arterial disease, cerebral thrombosis, etc.) There was a strong positive correlation between age-specific prevalence rate per 100,000 population and mean arsenic dose (r = + 0.9593) and a negative correlation between prevalence rate and mean age (r = 0.8789). These findings show that the prevalence rate declines with the advancing age and increases with the increase of arsenic dose. A multiple linear regression model E(y) = alpha + beta X1 + gamma X2, where y represents the age-specific prevalence rate per 100,000 population, X1 the mean arsenic dose, and X2 the mean age, was fitted to the data. The estimates of the parameters (alpha, beta, and gamma) were obtained by minimizing the residual sum of squares sigma(y - alpha - beta X1 - gamma X2)2. The following multiple linear regression equation was obtained: Y = 202.161 + 8452.455 X1 - 2.394 X2. Of the total variability in the prevalence rate, 96.22 per cent was accounted for by the multiple regression.

Adolescent

Limiting distribution under assortative mating.

A multi-locus model for complete positive assortative mating is discussed. For a two-locus model, if the gene frequencies for the two loci are different, as they are likely to be, it is shown that in equilibrium the population is not composed of only two homozygous types, as is usually thought. The limiting distribution will have three homozygous genotypes depending upon the initial gene frequencies. If there are m-loci such that gene frequencies at all loci are different, there will be (m+1) such homozygous genotypes present in the equilibrium population, one in each phenotypic group.

Crosses, Genetic