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Biomedical subjects

J A Nosek

Publications and source records attributed to J A Nosek.

5 recordsLinked to original sources
PubMed1992

Metabolism and disposition of 2,3,7,8-tetrachlorodibenzo-p-dioxin in ring-necked pheasant hens, chicks, and eggs.

The T 1/2 for whole-body elimination of [3H]-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) derived radioactivity in ring-necked pheasant hatchlings was 13 d, whereas in adult hen pheasants that were not producing eggs it was 378 d. All TCDD-derived radioactivity in hen tissues was from the parent compound. The oral bioavailability of TCDD in the adult hen pheasant varied with the environmental matrix, with 30% of the dose absorbed from a suspension of earthworms, 33% absorbed from a soil suspension, 41% absorbed from a suspension of paper mill sludge, and 58% absorbed from a suspension of crickets. A cumulative dose of 1.0 micrograms TCDD/kg body weight, administered as weekly doses of 0.1 micrograms/kg for 10 wk, did not adversely affect hen condition or egg production. Under these exposure conditions, hens translocated about 1% of their cumulative TCDD dose to each of the first 15 eggs laid. All of the TCDD-derived radioactivity in the eggs was the parent compound and was confined entirely to the yolk; no TCDD was detected in egg albumin. We conclude that TCDD was more persistent in pheasant hens than in chicks and that egg laying was an important route of elimination in the hen.

Administration, Oral↗
PubMed1992

Toxicity and reproductive effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin in ring-necked pheasant hens.

Hen pheasants (Phasianus colchicus) injected with graded single doses of TCDD (6.25, 25, or 100 micrograms/kg) exhibited delayed-onset body weight loss and mortality--classic signs of the wasting syndrome. The lowest single dose of TCDD to produce this effect was 25 micrograms/kg. When hen pheasants were treated weekly with far lower doses of TCDD (0.01-1.0 microgram/kg/wk) for 10 wk, signs of the wasting syndrome and mortality were also produced. The lowest cumulative TCDD dose required to produce the response, using a weekly dosing regimen, was 10 micrograms/kg. Furthermore, using this dosing regimen, egg production by hens treated with a cumulative TCDD dose of 10 micrograms/kg was reduced, as was hatchability of their eggs. We conclude that hen pheasants are responsive to the overt toxic effects of TCDD and that the lowest cumulative dose of TCDD that produces overt signs of toxicity, 10 micrograms/kg, also reduces egg production and egg hatchability.

Animals↗
PubMed1980

Antenatal corticosteroids to prevent neonatal respiratory distress syndrome: risk versus benefit considerations.

The clinician considering administration of steroids to prevent respiratory distress syndrome (RDS) should attempt to identify patients who do not have criteria previously shown to increase the likelihood of benefit in the prevention of RDS. It is possible to accurately predict the interval to delivery in most cases. Four hundred thirty-nine patients at risk to deliver prior to 37 weeks have been screened for factors known to decrease the likelihood of benefit. Only 47 (10.7%) screened candidates have no exclusion criteria. Twenty-seven (6.9%) of 392 excluded neonates developed RDS; 20 of the 27 were predicted to and did deliver in less than 24 hours after initial screening. Only one case was inappropriately excluded. Fetal surfactant assessment is crucial; pulmonary maturity excludes 19% at 28 to 33 weeks and 35% at 34 to 37 weeks. Careful screening for exclusion factors known to decrease the likelihood of steroid derived benefit is essential when use of a drug with potential long-term consequences (risk) is considered.

Adrenal Cortex Hormones↗