Genetic relationships between feral cattle from Chirikof Island, Alaska and other breeds.

The origin of cattle on Chirikof Island, off the coast of Alaska, is not well documented. We assessed genetic differentiation of cattle isolated on Chirikof Island from several breeds commonly used for commercial production in North America including breeds popularly believed to have contributed to the Chirikof Island population. A set of 34 microsatellite loci was used to genotype Angus, Charolais, Hereford, Highland, Limousin, Red Angus, Salers, Shorthorn, Simmental, Tarentaise and Texas Longhorn cattle sampled from North America and the Chirikof Island population. Resulting F(ST) statistics for these loci ranged from 0.06 to 0.22 and on average, 14% of total genetic variation was between breeds. Whether population structure was modelled as a bifurcating tree or genetic network, Chirikof Island cattle appeared to be unique and strongly differentiated relative to the other breeds that were sampled. Bayesian clustering for multiple-locus assignment to genetic groups indicated low levels of admixture in the Chirikof Island population. Thus, the Chirikof Island population may be a novel genetic resource of some importance for conservation and industry.

Screening flexible sigmoidoscopy by primary care physicians. Effectiveness and costs in patients negative for fecal occult blood.

A total of 252 consecutive screening flexible sigmoidoscopies were done by two community-based general internists on asymptomatic patients with stool negative for occult blood. Neoplastic lesions were found in 26 patients (10.3%), including 27 adenomatous polyps, 2 with carcinoma-in-situ and 1 carcinoid tumor. No complications resulted from flexible sigmoidoscopy. Nineteen patients with positive screening sigmoidoscopy underwent colonoscopy, and additional adenomatous polyps were found in six patients (31.6%), but no additional malignancy. Total cost for screening flexible sigmoidoscopy and additional studies was $30,359 ($1,168 per patient with a polyp or malignancy and $10,119 per patient with a malignant lesion). Screening flexible sigmoidoscopy can be safely done by community-based general internists in asymptomatic patients with a diagnostic yield comparable with that reported by subspecialists; total costs are acceptable.

Effect of the diphosphonate EHDP on bone mineral metabolism during prolonged bed rest.

The effect of disodium ethane-1-hydroxy-1, 1-diphosphonate (EHDPTM) on bone mineral metabolism was tested in 4 healthy young men during 20 weeks of continuous bed rest. Two subjects received an oral dose of 5 mg/kg/day and the other 2 20 mg/kg/day. The low dose had two minor effects: the increase in bone accretion rate which usually occurs during bed rest was prevented, and there was an accentuation of the bed rest induced increase in hydroxyproline excretion. Skeletal mineral loss, assessed by calcium balance measurements and gamma ray absorptiometry of the calcaneus, occurred at the rate previously noted in untreated control subjects. Two types of drug effect were apparent at the higher dosage: one was immediate and sustained--a rise in serum phosphorus concentration and a fall in serum alkaline phosphatase activity. The other was delayed and progressive--a decline in urinary hydroxyproline excretion and in the rates of bone accretion and resorption. Skeletal mineral loss may have been affected; the usual negative mineral balance developed during the first half of the study, then disappeared during the last few weeks. However, gamma ray absorptiometry revealed no attenuation of the calcaneal mineral losses.