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Biomedical subjects

C G Lewis

Publications and source records attributed to C G Lewis.

At least 73 records · Page 4Linked to original sources
PubMed1989

The predictive value of hemodynamic studies in preclinical ischemic necrosis of bone.

This study evaluated the predictive value of bone marrow pressures and intraosseous venography in joints at risk for developing ischemic necrosis of bone. Forty-two patients with ischemic necrosis of bone had hemodynamic studies performed on their contralateral, asymptomatic joint. A followup evaluation of symptoms and radiographs was obtained to establish the prevalence of clinical ischemic necrosis in the index joints. Thirty-six of 48 joints had increased bone marrow pressure and of these, 15 (42%) developed histologically or radiographically confirmed ischemic necrosis of bone. In none of the 12 bones with normal bone marrow pressure did ischemic necrosis of bone occur (p = 0.005). Venography was also significantly predictive for ischemic necrosis of bone, both alone and in conjunction with bone marrow pressure. Our study reaffirms the risk of developing bilateral ischemic necrosis of bone (31% at a mean followup of 47 months) once the diagnosis has been made on one side. Bone pressure measurements are of predictive value in establishing those joints which require close clinical followup so that detection of disease may be in the precollapse stage of ischemic necrosis of bone.

Adult↗
PubMed1988

Changes in pancreatic enzyme specific activities of rats fed a high-fructose, low-copper diet.

This study describes the progressive changes in exocrine pancreatic enzyme specific activities from rats provided with a diet containing either 62% starch (S) or fructose (F) with 6.0 ppm copper (+Cu) or 0.6 ppm (-Cu) from 21 to 61 days of age. Copper-deficient rats had significantly reduced pancreatic weight and DNA, RNA, protein and copper content and superoxide dismutase (SOD) activity after consuming diet for 39 days. These reductions were far more severe in F-Cu than in S-Cu rats. Copper deficiency significantly reduced pancreatic amylase and lipase specific activities, but the effect was more severe in the F-Cu dietary group. Chymotrypsinogen and trypsinogen specific activities were reduced only in the F-Cu dietary group and the CHO x Cu interaction was significant. High dietary fructose and low dietary copper in combination interact to produce severe reductions in pancreatic amylase, lipase, chymotrypsinogen, and trypsinogen specific activities which could not be explained by either copper deficiency or by an increase in dietary fructose alone.

Amylases↗
PubMed1988

Exocrine pancreatic enzyme activities and mineral concentrations in SHR/N-corpulent (cp) male rats.

Exocrine pancreatic enzyme activities and mineral concentrations were measured in a newly developed congenic strain of corpulent rat (SHR/N-cp). Approximately 4- to 5-wk-old corpulent (cp/cp) and lean (+/?) male rats consumed a diet containing 54% carbohydrate as either cooked cornstarch or 27% cooked cornstarch and 27% fructose for 9.5 mo. After consuming the diet for 3 mo, corpulent rats were hyperinsulinemic, hyperlipidemic and exhibited glycosuria. After consuming the diet for 9.5 mo corpulent rats were twofold heavier and pancreatic weight was 77% that of their lean littermates. Corpulent rats that consumed starch exhibited lower total pancreatic protein with no significant change in total DNA and RNA. In the corpulent rat, both lipase- and chymotrypsinogen-specific activities and both the specific activities and the content of amylase or trypsinogen were lower than those of lean littermates. Fructose consumption resulted in lower pancreatic copper and iron concentrations, and zinc concentration was elevated in corpulent rats. This study suggests that the SHR/N-corpulent rat may be a useful model for studying exocrine pancreatic function in insulin-independent diabetes.

Amylases↗
PubMed1988

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Insurance, Dental↗
PubMed1987

Alteration of pancreatic enzyme activities in small intestine of rats fed a high fructose, low copper diet.

This study describes the progressive effects on pancreatic enzyme activities from washings of the small intestine of rats fed diets containing either 62% starch (S) or fructose (F), with 0.6 mg copper/kg diet (-Cu) or 6.0 mg copper/kg diet (+Cu) from 21 to 61 d of age. Hepatic copper concentration of the copper-deficient groups was 50% of that of the copper-supplemented groups. Body and relative pancreatic weights were lower in the F-Cu dietary group than in any other group. Relative liver weight was significantly higher in the fructose dietary groups than in the starch dietary groups. There were significant carbohydrate (CHO) X week and Cu X week interactions for luminal amylase activities and the CHO X Cu X week interaction was significant for luminal lipase and trypsin activities. The lowest enzyme activities were observed in the F-Cu-fed rats. The CHO X week interaction was significant for chymotrypsin with the lowest enzyme activities in the fructose-fed rats. It appears that high dietary fructose and low dietary copper interact to produce greatly reduced pancreatic enzyme activities in small intestinal washings. We speculate that subsequent digestive and absorptive abnormalities during a period of rapid growth may account for the severe morbidity and mortality in copper-deficient, fructose-fed rats.

Amylases↗
PubMed1987

Sexual differences in the expression of copper deficiency in rats.

The present investigation was undertaken to establish whether the severity of copper deficiency in rats fed diets containing fructose is affected by the presence and type of endogenous sex hormones. Intact and castrated male rats and intact and ovariectomized females were fed from weaning a copper-deficient diet (0.6 ppm) containing 62% fructose for 8 weeks. Regardless of castration, male rats were anemic, exhibited heart hypertrophy, and died of the deficiency. However, castration ameliorated the anemia and delayed the mortality. In contrast, none of the females died of the deficiency. It is suggested that in addition to the sex of the animal, levels of testosterone in the male may also play a role in the severity of copper deficiency.

Animals↗
PubMed1982

Ribonucleic acid metabolism in rat liver during long-term adaptation to malnutrition.

Ornithine decarboxylase (ODC) and nucleolar DNA-dependent RNA polymerase (RNA polymerase I) activities increased in the liver of young adult male rats fed a 6% casein diet (malnourished) for 1 week when compared with rats fed a 25% casein diet (control). ODC activity increased progressively and reached a peak after 3 weeks of malnutrition and then decreased to control values by 5 weeks. RNA polymerase I reached peak activity 1 week after malnutrition was imposed, decreasing thereafter to control values by 3 weeks. At 4 and 5 weeks, RNA polymerase I activity in malnourished animals was lower than control. Nucleoplasmic DNA-dependent RNA polymerase activity remained unchanged in the first 2 weeks of malnutrition and decreased thereafter to values significantly lower than control. The data confirm our previous observations of cyclical changes during prolonged malnutrition and suggests a process of "biochemical adaptation" to malnutrition in which the organism enhances essential metabolic processes to maintain cellular homeostasis to the detriment of less essential functions like systemic growth.

Adaptation, Physiological↗
PubMed1981

Vitamin A and vitamin E concentration of the milk from mothers of pre-term infants and milk of mothers of full term infants.

The vitamin E, vitamin A and beta carotene concentrations of milk, from eight mothers delivering premature infants and ten mothers delivering full term infants were determined and compared. Milk samples were collected three times per day on days 3, 9, 15, 21, 27 and 33 postpartum. Dietary records were kept on days 2-3, 14-15, and 32-33. There was no significant difference in vitamin E, vitamin A and beta carotene levels between the two groups. The mean retinol concentration was higher in the milk of mothers of premature infants on all days except day three. The highest mean carotene and retinol concentrations in the milk of mothers of full terms infants were on day three: but the peak occurred in the preterm group on day nine and did not drop as rapidly as the milk retinol of the full term group. The milk of mothers of fullterm infants, day 3 vitamin E concentration was significantly higher than days, 15, 21, 27 and 33 postpartum. There were no significant differences in the dietary intake of the full term and preterm groups. The amount of vitamin E in the milk was not affected by dietary vitamin E intake of the subjects regardless of gestational age of the infant. More research is needed to determine the exact quantity of vitamin A and E ingested by the premature infants if breastfed by their respective mothers.

Adult↗
PubMed1978

Studies on ribosomal RNA synthesis in vivo in rat liver during short-term protein malnutrition.

To better understand the increased incorporation of [14C] orotate into rRNA, as detailed study of liver rRNA synthesis was performed on young rats fed a 6% casein diet for 1 week. From 10 to 180 minutes after i.v. injection of [14C] orotate, nucleolar RNA specific activity of malnourished rats was 1.6 times higher than controls. Polyacrylamide gel electrophoresis revealed that 45S pre-rRNA from malnourished rats was synthesized more rapidly than controls. Specific activities of other nucleolar RNA species was increased but the time of appearance of labeled peaks did not change. The cellular cytoplasmic rRNA pool was reduced to 70% of controls, the time of appearance of labeled rRNA in the cytoplasm was the same, but cytoplasmic rRNA specific activity was 2.1 times greater than controls. Absorbance profiles and radioactivity patterns of nucleoplasmic RNA were similar in the two groups of rats. Nucleoplasmic radioactivity patterns were complex and heterodispersed, and the amount of radioactivity was greatest in RNA from malnourished rat liver. Our data indicate that short-term dietary protein restriction leads to cellular events which increase the synthesis of nuclear RNA. Nucleolar RNA is processed and transported to the cytoplasm in a manner similar to controls.

Animals↗
PubMedDate not supplied

Effect of coenzyme Q10 supplementation on cardiac hypertrophy of male rats consuming a high-fructose, low-copper diet.

Administration of coenzyme Q10 to humans and animals has a beneficial effect on a number of cardiac diseases. The purpose of the present study was to determine if coenzyme Q10 treatment could ameliorate cardiac abnormalities associated with the carbohydrate x copper interaction in rats. Weanling male rats were provided with a copper-deficient diet (0.6 microgram Cu/g) containing either 62.7% starch (S-Cu) or fructose (F-Cu) for 5 wk. Half of the rats provided with the F-Cu diet were given daily oral supplements of 300 mg coenzyme Q10/kg body weight (F-Cu + Q). Heart hypertrophy, liver enlargement, or pancreatic atrophy were not affected by, nor was body growth or anemia improved by, supplementation with coenzyme Q10 when compared to rats fed only the F-Cu diet. Hearts from rats fed the F-Cu diet had severe inflammation, degeneration, fibrosis, and giant mitochondria with abnormal cristae. Hearts from F-Cu + Q rats had similar mitochondrial changes as the F-Cu rat hearts but without any apparent degenerative changes. None of the F-Cu + Q rats, but 30% of the F-Cu rats, died during the study as a result of heart rupture. These observations show that whereas coenzyme Q10 treatment did not prevent the cardiac hypertrophy of the carbohydrate x copper interaction, it did play a role in maintaining the integrity of the heart.

Animals↗
PubMedDate not supplied

Dietary carbohydrate influences tissue fatty acid and lipid composition in the copper-deficient rat.

Fructose and copper have been shown independently to influence long chain fatty acid metabolism. Since fructose feeding exacerbates copper deficiency, their possible interaction with respect to tissue long chain fatty acid and lipid composition was studied. Weanling male Sprague-Dawley rats were given diets containing 0.6 or 6 mg/kg copper. The carbohydrate source (627 g/kg) was either fructose or corn starch. After 3 wk, fatty acid profiles and total lipids in heart and liver were analyzed. Copper-deficient rats fed fructose had more severe signs of copper deficiency than those fed starch, according to heart/body wt ratio, hematocrit, and liver copper content. The fatty acid composition of heart and liver triacylglycerol was significantly different between groups, but the changes did not correlate with the severity of copper deficiency. In heart, phosphatidylinositol and phosphatidylserine, arachidonic acid and docosapentaenoic acid (n-6) were increased 193 and 217%, respectively, p less than 0.05) in rats given the copper-deficient diet containing fructose. Changes in the long chain fatty acids in heart phospholipids may be related to the higher mortality commonly observed in rats fed a copper-deficient diet containing fructose.

Animals↗
PubMedDate not supplied

Antioxidant defense mechanisms in the male rat: interaction with alcohol, copper, and type of dietary carbohydrate.

The activities of enzymes participating in cellular protection against free radical reactions were measured in hepatic tissues from copper-adequate and copper-deficient rats fed fructose or starch-based diets. Half of the rats consumed 20% ethanol in their drinking water. The consumption of ethanol depressed growth rate, reduced hematocrit, and hepatic copper concentration. Feed efficiency was greatly depressed by ethanol. Mortality due to copper deficiency occurred in fructose-fed rats and in starch-fed rats that drank ethanol. Ethanol had no effect on superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), or catalase. In contrast, copper deficiency reduced SOD and fructose feeding depressed catalase activity. GSH-Px was not affected by either the type of dietary carbohydrate, copper, or ethanol. Taken together, these data suggest that additional mechanisms to antioxidant defense systems are responsible for the metabolic changes that occur during the interactions between ethanol low copper and dietary carbohydrates.

Animals↗
PubMedDate not supplied

Antioxidant defense mechanisms in the female rat: interactions with alcohol, copper, and type of dietary carbohydrate.

The purpose of this study was to examine the effects of ethanol, type of dietary carbohydrate (fructose vs. starch), and levels of dietary copper (deficient vs. adequate) on antioxidant defense mechanism in the female rat. The consumption of 20% ethanol in the drinking water depressed growth rate due to a reduction of feed efficiency. Ethanol also lowered hepatic copper concentration, but had no effect on hepatic iron. Among the three antioxidant enzymes studied [i.e., superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase], only catalase activity was increased by ethanol. This effect was independent of copper or the type of dietary carbohydrate. As expected, copper deficiency dramatically reduced SOD. Copper deficiency also reduced GSH-Px activity; however, the combination of fructose feeding with copper deficiency caused a further reduction in GSH-Px. The data show that copper deficiency, per se, and the combination of copper deficiency with fructose feeding lower the antioxidant defense system in female rats.

Alcohol Drinking↗