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R B Rucker

Publications and source records attributed to R B Rucker.

116 records · Page 7Linked to original sources
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Ascorbic acid turnover in the mouse following acute ozone exposure.

Swiss Webster mice were continuously exposed to an atmosphere containing 1.5 ppm ozone (O3) for 5 days. Control mice breathed filtered air. Immediately following the exposure period each mouse was then injected with [1-14C] ascorbic acid. The rate of disappearance of [1-14C] ascorbic acid and the levels of total ascorbic acid were determined in serum, lung, liver, and the remaining carcass over a 9-day period. O3 exposure caused transient decreases in the ascorbic acid levels in liver and serum, whereas lung ascorbic acid levels increased. The apparent biological half-life of ascorbate in carcasses (minus lung and liver) from O3-exposed mice, was significantly prolonged. Significant changes were also observed in the net flux of ascorbic acid in all tissues examined. The results indicated that the change in ascorbic acid levels in a given tissue appeared to reflect changes in the rate of ascorbic acid degradation, its mobilization or tissue compartmentalization, rather than increased synthesis in response to O3 exposure.

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Effect of maternal diabetes and dietary copper on fetal development in rats.

To test whether diabetes associated alterations in copper metabolism contribute to diabetes-induced teratogenicity in rats, pregnancy outcome was compared between diabetic and nondiabetic rats fed either a copper adequate (12 micrograms/g diet) or low copper diet (1 microgram/g diet). The dietary regimen was begun two weeks prior to mating and continued throughout pregnancy. To facilitate the reduction of maternal copper stores in the low copper groups, the low copper diet was supplemented with a copper chelator, triethylenetetraamine, at 1% for one week; the chelator was removed from the diet one week prior to mating. Pregnancy was terminated on gestation day 20. Maternal and fetal tissues were assessed for copper concentrations, the activities of the cuproenzymes copper, zinc superoxide dismutase and ceruloplasmin, and the copper binding protein metallothionein. Dams fed the low copper diet had low tissue copper concentrations, and low plasma ceruloplasmin and erythrocyte superoxide dismutase activities compared to copper-adequate dams. Fetuses in the low copper groups were characterized by low liver copper concentrations. Gross structural and skeletal anomalies were only observed in the diabetic groups; maternal copper intake did not influence the frequency of these anomalies. However, fetuses in the low-copper nondiabetic group, and both diabetic groups, were characterized by low liver copper, zinc superoxide dismutase activity suggesting that fetal copper metabolism was influenced by both copper intake and diabetes.

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Effect of a metallothionein antisense oligonucleotide on embryo development.

The effect of a metallothionein (MT) antisense oligodeoxynucleotide (ODN) on mouse preimplantation embryo development was investigated. Preimplantation embryos were cultured for 72 h and examined following exposure to either an MT antisense or sense ODN. Blastocyst formation (cavitation) and embryo cell number were lower in embryos exposed to the MT antisense ODN than in controls or in embryos exposed to the MT sense ODN. In embryos cultured in medium containing free nucleotides, cavitation frequency was not affected, although mean embryo cell number was lower than in controls. Combined, this work shows that an antisense ODN against MT can significantly affect blastocyst formation of preimplantation embryos; some, but not all, of the observed effects on embryo cell number may have been due to nucleotide toxicity.

Analysis of Variance↗
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Watanabe hyperlipidemic rabbit as a model of aortic degeneration of the medial lamellar elastin unit.

At age 3 years, WHHL rabbits are near the end of their lifespan, frequently dying from the progression of their hyperlipidemic disease from events such as myocardial infarction. Out of a colony of 20 three-year-old WHHL rabbits raised as part of a NIH breeding project, 2 rabbits actually died of a ruptured thoracic aortic aneurysm. The need for a model to study abdominal aortic aneurysm formation led us to explore further the abdominal aortic pathology in aged WHHL rabbits. Six rabbit abdominal aortas from 3-year-old WHHL rabbits were preserved in formalin, sectioned, and stained for elastin. These were compared to the same sections of six normolipidemic age matched New Zealand white (NZW) rabbits. There was significant (P less than or equal to .001) destruction of the medial lamellar elastin unit in the aorta of the WHHL rabbits compared with the control NZW rabbits. Severe cholesterol deposits appeared to destroy the medial lamellae from the inside out. No definite aneurysm formation was seen in the abdominal aorta despite the significant changes in the medial lamellar elastin units. Thus, this model could be used to study the elastin degeneration of the media, but not necessarily abdominal aortic aneurysm formation.

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PubMedDate not supplied

New perspectives on function of vitamins.

Newer aspects of vitamin function are reviewed from a biochemical perspective. Specifically, six themes are developed that include 1) mechanisms and biochemical functions important to oxidant defense, 2) new functions associated with the actions of vitamin D, 3) vitamin K and calcium homeostasis, 4) folic acid and the methylation of DNA, 5) beta-carotene and cellular communication, and 6) newly identified roles for vitamin B6. A decade ago, it was considered highly speculative to propose approaches to disease prevention that involved vitamin supplementation. Nutrition paradigms important to vitamin function, however, have now shifted to include more focus on disease prevention and consideration of supplements. Considerable work has also evolved to provide basic biochemical and physiological mechanisms as bases for the interaction between vitamin status and health.

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