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A rapid method for the determination of relative absorption of dietary lead by rats is described. The influence of age, weight and dose rate has been determined and using standard conditions the tissue lead content of blood, kidney and femur are significantly correlated with each other and are a function of ingested lead. Eight lead compounds were evaluated using this technique and the findings related to lead acetate as a reference compound. Of the inorganic preparations studied, lead carbonate (basic) and metallic lead showed a twelve-fold difference in absorption, with the remaining compounds giving intermediate values. The absorption of lead from four organic compounds was determined from diets containing 7·5% corn oil added to the standard diet. Lead tallate was absorbed to the same degree as lead acetate, but lesser absorptions resulted from lead octoate, naphthenate and alsynate. The addition of corn oil to a final concentration of 7·5% of the diet enhanced the absorption of lead acetate. [ABSTRACT FROM PUBLISHER]

The lead burdens for children and mothers exposed to lead-contaminated soils and dusts have been investigated in a rural district with minimal atmospheric pollution. A significant relationship was observed between the lead content of blood and hair of children exposed to soils of mean lead content in the range 420-13,969 p.p.m. The blood lead concentration of children was consistently greater than that of their mothers. No consistent relationship was found between blood lead values and pica for soil. In this situation, lead in soil provided a small additional burden for children but in itself was insufficient to constitute a hazard. [ABSTRACT FROM PUBLISHER]

The nutritional factors which affect lead absorption have been studied. Synthetic diets of known composition were compounded to contain 0·075% Pb as PbCl labelled with Pb. Rats were exposed to lead for periods of 48 hr. The dietary intake was then measured and the absorption of lead determined by means of a whole-body counter. Lead absorption was increased by high fat, low mineral, low protein and high protein diets but was decreased by high mineral diet. Low fat, low fibre, high fibre, low vitamin and high vitamin diets had no effects on lead absorption. [ABSTRACT FROM PUBLISHER]

The kinetics of the interaction of lead with human erythrocytes has been investigated by means of tracer studies with Pb. The elution characteristics of lead from erythrocytes in contact with EDTA suggest the existence of two binding sites differing in their affinity for lead. The findings are consistent with the existence of two compartments for lead binding in the cell, and a model system based on this concept is proposed. [ABSTRACT FROM PUBLISHER]

The significance of calcium soap formation in the inhibition of calcium absorption has been studied in rats. 47Ca labelled soaps of fatty acids were introduced into the duodenum and the absorption of calcium measured after four hours in a whole body counter. The absorption of calcium was inversely correlated with the chain length of the fatty acid varying from 1% for Ca-stearate to 60% for Ca-hexanoate. Increasing the degree of unsaturation of the fatty acid was accompanied by increased calcium absorption. The availability of calcium for absorption from the soaps was correlated with their solubility in 1% aqueous Na-tauroglycocholate. The percentages of calcium as soap in the small intestine and the faeces after intragastric administration of calcium and fats were similar, which suggests that the faecal content of calcium soaps is an index of intestinal soap formation. Soap formation was negligible when CaCl2 was given with tristearate, triolaeate, or tridecanoate and no depression of calcium absorption was observed. Calcium absorption was markedly impaired by the addition of phosphates at a Ca/P ratio of 1:1 irrespective of the presence of neutral fats. Stearic acid resulted in significant soap formation and reduced calcium absorption. The degree of Ca-soap formation and the inhibition of calcium absorption were well correlated. The results suggest that, although calcium soap formation may markedly depress calcium absorption in the rat, no significant soap formation takes place when fats are given in the form of triglycerides. [ABSTRACT FROM PUBLISHER]

Unlabelled: Peripheral blood lymphocytes subsets were examined in 233 healthy school children aged 4.9-13.7 years at the time of examination. Lymphocyte subsets were characterized according to the following cluster of differentiation (CD) numbers: CD2, CD4, CD8 and CD19 and quantified according to both their absolute number and as a percentage of total lymphocytes. For the purpose of analysis, the LMS (lambda, mu, sigma) method was utilized, with a 3%-97% confidence interval. Smoothing of the generated curves, was by multiple regression analysis, using the least squares method. The results of these analyses indicate distinct trends as a child ages, both in absolute numbers and in the percentage of each cell type.Conclusion: We characterized lymphocyte subsets in children aged 4.8-13.7 years. These data should prove of considerable value to pediatricians dealing with patients with known or suspected immunological problems, and ought to be used in place of the commonly used, but inappropriate, adult lymphocyte subset ranges. [ABSTRACT FROM AUTHOR]

Low birthweight infants aged 4-41 days were given from birth one of three experimental milk formulae varying widely in content of calcium and phosphate. Ca and P in feed, urine, and faeces were measured between carmine markers corresponding to a metabolic period of 48 hours. Calcium enriched in 46Ca to provide a marker for the dietary Ca was added to one feed and 46Ca measured in urine and faeces. True absorption of Ca and endogenous excretion into the bowel could then be inferred. True absorption of Ca was proportional to Ca intake and independent of P intake. Endogenous faecal excretion seemed to be independent of both Ca P intakes, and varied widely between different infants in the range 4-150 mg/day. Urine Ca was low and retention was essentially the difference between true absorption and endogenous faecal excretion. Retention of Ca tended to be much greater on a high Ca intake, but the variability in retention between infants on a given intake was large, paralleling the variability in endogenous faecal excretion. The variability in plasma Ca concentrations in newborn infants may in part be a consequence of wide individual variability in endogenous faecal excretion. The 46Ca marker technique provides a means of investigating the factors determining this variability. [ABSTRACT FROM AUTHOR]

Disease of the lower motor neurone is a recognized hazard of lead toxicity, but the importance of contact with lead in the causation of motor neurone disease has not previously been ascertained. In 74 cases of motor neurone disease, 15% had a history of extensive exposure to lead, compared with 5·4% of a control group. The five year survival rate of these patients was 54%, compared with 16% in the remainder. The more benign course of the disease in some of these cases may be due to treatment with chelating agents. A history of either disease of the axial skeleton or previous fracture was obtained in 25% of patients compared with 9·4% of controls. There may be a relationship between skeletal demineralization and the development of motor neurone disease. The lead content of iliac crest bone biopsy specimens in 25 patients with motor neurone disease was no greater than that of a control group, but this does not exclude the possibility that lead liberated from bone might affect the motor neurone. [ABSTRACT FROM AUTHOR]