Bioavailability of lead to juvenile swine dosed with soil from the Smuggler Mountain NPL Site of Aspen, Colorado.

Bioavailability of lead (Pb) has become an issue in quantifying exposure of sensitive populations and, where necessary, establishing cleanup levels for contaminated soil. Immature swine were used as a model for young children to estimate the degree to which Pb from two fully characterized composite samples from the Smuggler Mountain Superfund Site in Aspen, Colorado may be bioavailable to resident children. The composite soils contained 14,200 and 3870 micrograms Pb/g of soil. Relative and absolute enteric bioavailabilities of Pb in soil (oral dose groups of 75,225, and 675 micrograms Pb/kg body wt/day) were estimated by comparison with an orally administered soluble Pb salt (lead acetate = PbAc2.3H2O) (dose groups of 0, 75, and 225 micrograms Pb/kg body wt/day) and an intravenously administered aqueous solution of Pb (100 micrograms Pb/kg/ day) from the same trihydrate salt administered daily for 15 days to 50 juvenile swine. The biological responses (area under the blood Pb concentration-time curve, and the terminal liver-, kidney-, and bone-lead concentrations) produced by Pb from PbAc2.3H2O and lead-contaminated soils were determined. This study revealed Pb from soil containing 14,200 micrograms Pb/g of soil had a bioavailability relative to Pb from PbAc (RBA), ranging from 56% based on the area under the blood lead concentration-time curve (AUC) versus dose, to 86% based on calculations from liver-Pb loading versus dose. Similarly, Pb from soil containing 3870 micrograms Pb/g of soil had an RBA ranging from 58% based on the AUC versus dose, to 74% based on calculations from liver- and kidney-Pb loading versus dose. Bioavailability of Pb in soils may be more or less than EPA's default RBA of 60%, therefore, measuring site-specific RBAs provides a basis for improved exposure and risk assessment.

Epidemiologic risk factors associated with canine systemic mycoses.

A prevalence study was designed to evaluate host and seasonal risk factors associated with three systemic mycoses in dogs: blastomycosis, coccidioidomycosis, and histoplasmosis. Histoplasmosis was the most commonly diagnosed of the three diseases. All three of the mycoses occurred more frequently in male than female dogs. Compared to dogs less than 2 years of age, those 4--7 years of age were at increased risk of developing coccidioidomycosis whereas dogs 2--7 years of age were at increased risk of developing histoplasmosis. Three breeds, i.e., Pointer, Weimaraner and Brittany Spaniel, had increased risk of having histoplasmosis infections. Seasonal analysis with an epidemiologic trend model indicated that all three systemic mycoses have different but strong seasonal trends.

Selected biological values of the African white-tailed sand rat (Mystromys albicaudatus).

Forty-three female and 44 male, sexually mature normal African sand rats (Mystromys albicaudatus) provided serum and urine for determining normal ranges of selected serum chemistry and electrolyte determinations and for routine nonfasted urinalyses. Serum chloride and serum glucose levels were greater and serum sodium levels lower for female rats. An unusually high physiological level of urine protein was detected, and it was determined that standard dipstick methods for determining urine protein levels in this species gave artificially high results. Ketouria and glycosuria were more common in males than in females, but these determinations were not correlated to blood urea nitrogen or to serum glucose levels. No association was found between body weight and any of the serum chemistry, electrolyte or urinalysis variables examined.

Epizootiologic features of canine hydrocephalus.

In a retrospective study of hydrocephalus (of congenital origin) diagnosed in 564 dogs, 11 breeds (including 8 "toy" breeds) were identified as being a significantly high risk. An inverse relationship between risk and body size was detected. The smaller the dam at maturity, either in height at the shoulder or body weight, the greater the risk of hydrocephalus in the offspring.

Organ weights and organ:body weight ratios of the African white-tailed rat (Mystromys albicaudatus).

Fifty-three adult female and 51 adult male white-tailed rats (Mystromys albicaudatus) were killed with ether and weighed; the spleen, kidneys, liver, heart, lung, pancreas, brain and gonads were dissected free of adhering tissue and weighted. The mean absolute organ weight and organ:body weight ratios by sex and organ were calculated and compared. The male rats were significantly (p less than or equal to 0.05) heavier. The mean weight of the males was 110.0 +/- 23.8 g versus 82.9 +/- 16.1 g for the females. The absolute weights of the heart, liver and kidneys were significantly (p less than or equal to 0.05) greater for the males. The organ:body weight ratios, except for heart and brain (excluding ovary and testicle), were unaffected by sex. The heart to body weight ratio and the brain to body weight ratio were significantly (p less than or equal to 0.05) larger in female rats.