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K K Carroll

Publications and source records attributed to K K Carroll.

At least 55 records · Page 3Linked to original sources
PubMed1990

Influence of dietary minerals on apolipoprotein B metabolism in rabbits fed semipurified diets containing casein.

Rabbits were fed semipurified casein diets containing either 4% or 2.5% mineral mix for 8 weeks. Both groups maintained weight throughout the experimental period. The plasma total cholesterol concentration was significantly higher after 4 weeks on diet and slightly higher after 8 weeks in animals fed the lower level of minerals. Plasma IDL- and LDL-cholesterol concentrations after 4 weeks and HDL-cholesterol concentrations after 8 weeks were significantly higher in animals fed the 2.5% compared to those fed the 4% mineral mix. Kinetic experiments showed that in rabbits fed the lower level, the fractional catabolic and production rates of VLDL-apo B were lower and a greater proportion of IDL-apo B was derived from sources other than VLDL compared to the animals fed the higher level. LDL-apo B kinetics were not significantly different between the 2 groups. These data suggest that a reduction in dietary minerals enhances casein-induced hypercholesterolemia.

Animals↗
PubMed1990

Essential amino acids in relation to hypercholesterolemia induced in rabbits by dietary casein.

Rabbits fed a cholesterol-free, semi-purified diet containing 25% casein amino acids (25% AA) for 2 wk had significantly higher serum total and low density lipoprotein (LDL) cholesterol levels than animals fed the same diet containing 11.2% casein amino acids (11.2% AA). These results were similar to those obtained by feeding diets containing 27% and 12% casein, respectively. When rabbits were fed the 11.2% AA diet supplemented with essential amino acids to the 25% level (11.2% AA + essential AA), their LDL cholesterol level was significantly higher than that in animals fed the 11.2% AA diet supplemented with nonessential amino acids to the 25% level (11.2% AA + nonessential AA). LDL protein and phospholipid levels were significantly higher in rabbits fed the 25% AA diet than in those fed 11.2% AA and tended to be elevated in animals fed 11.2% AA + essential AA compared to those fed 11.2% AA + nonessential AA. Fecal excretion of bile acids and cholesterol was similar with all dietary regimens, and the level of liver lipids showed no correlation with the degree of hypercholesterolemia produced by dietary amino acid mixtures.

Amino Acids↗
PubMed1990

Intermediate density lipoprotein-apolipoprotein B turnover in rabbits fed semipurified diets containing casein or soy protein.

The aim of this study was to investigate the underlying causes of elevated levels of intermediate density lipoprotein (IDL) in rabbits fed casein compared to soy protein in a cholesterol-free, semipurified diet. Kinetic studies were carried out in which homologous, radiolabelled IDL was injected into casein- and soy protein-fed animals after a period of 7 months on diet. Total plasma cholesterol and IDL cholesterol and protein were significantly higher in animals fed casein compared to those fed soy protein. The fractional catabolic rate of IDL-apolipoprotein B was significantly lower in casein-fed animals but the difference in mean values for the production rate did not reach statistical significance. The effect of feeding casein on IDL can be attributed to its reduced efficiency of removal from the plasma.

Animals↗
PubMed1990

Effects of dietary protein on composition and metabolism of plasma lipoproteins in rabbits.

Changes in the concentration and composition of serum VLDL, LDL, and HDL were studied in rabbits transferred from Chow diets to cholesterol-free, semipurified diets containing casein or isolated soy protein. During the first week on the casein diet, there was a marked increase in LDL-cholesterol and these higher levels were maintained during the subsequent 3 weeks of the study. Similar but less marked changes were obtained with the soy protein diet. When the percent composition of the particles was determined, both VLDL and LDL had a higher proportion of cholesterol. Turnover studies indicated that the FCRs for radiolabelled VLDL and LDL were reduced in casein-fed animals compared to those fed soy protein. The elevated LDL levels in casein-fed rabbits were primarily due to a reduction in receptor-mediated catabolism of LDL-apo B. Receptor-independent removal in the two groups was similar. These studies show that the hypercholesterolemia in casein-fed rabbits, compared to those fed soy protein, is associated with cholesterol enrichment of LDL and impaired receptor-dependent removal of LDL-apo B.

Animals↗
PubMed1989

Effects of dietary fat, calcium, and vitamin D on growth and mammary tumorigenesis induced by 7,12-dimethylbenz(a)anthracene in female Sprague-Dawley rats.

This study was designed to test the influence of dietary calcium and vitamin D levels on the promotional effect of high-fat diets on chemically induced mammary carcinogenesis. In a small preliminary experiment (Experiment A), 40 female Sprague-Dawley rats, 43 days old, were randomly divided into 5 groups (8 rats/group) and fed a semipurified diet containing 3% sunflower seed oil (SF) by weight, 1.5 mg of calcium/kcal and 0.5 IU vitamin D/kcal of diet. After 1 week, each rat was given 2.5 mg of dimethylbenz(a)anthracene by gastric gavage. One week later, the animals were switched to 1 of 4 diets varying in fat (3 or 20% SF by weight), calcium (1.5 or 0.25 mg/kcal), vitamin D (0.5 or 0.05 IU/kcal), and phosphate or to a fifth diet containing 3% SF by weight, 0.1 mg of calcium/kcal and 0.05 IU of vitamin D/kcal. In all 5 diets, calcium:phosphate weight ratios were maintained at 1.2:1. In animals fed the high-fat diet, reduction of dietary calcium (1.5 to 0.25 mg/kcal) and vitamin D (0.5 to 0.05 IU/kcal) increased the incidence of mammary lesions from 37 to 75% and the total number of lesions from 4 to 16. A trend toward an increase in lesion weight and total lesion burden was also seen. To confirm these results, the experiment was repeated using the same protocol; 126 rats were divided into 6 groups, treated with dimethylbenz(a)anthracene, and fed the diets as described. A sixth diet was included that contained 20% SF by weight, 0.01 mg of calcium/kcal, and 0.05 IU of vitamin D/kcal. As for Experiment A, in animals fed the high-fat diet, reduction of dietary calcium (1.5 to 0.25 mg/kcal) and vitamin D (0.5 to 0.05 IU/kcal) resulted in an increase in total mammary lesions from 31 to 55, a significant increase in average lesion burden/rat with lesions (1.6 +/- 0.6 to 12 +/- 3 g), and a trend toward increasing weight of lesions. The effect was less obvious in animals fed the low-fat diet where, in both experiments, an increase in the incidence of mammary lesions was observed only when the dietary calcium was reduced from 1.5 to 0.1 mg/kcal. These data suggest that decreasing calcium and vitamin D increase the promoting effects of a high-fat diet on mammary tumorigenesis in the rat.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

Turnover of 125I-VLDL and 131I-LDL apolipoprotein B in rabbits fed diets containing casein or soy protein.

Rabbits fed low-fat, cholesterol-free, semi-purified diets containing casein developed a marked hypercholesterolemia compared to rabbits fed a similar diet containing soy protein (plasma cholesterol 281 +/- 31 vs. 86 +/- 9 mg/dl; P less than 0.05). Turnover studies (three per dietary group) were carried out in which homologous 125I-labeled VLDL and 131I-labeled LDL were injected simultaneously into casein- (n = 8) or soy protein- (n = 9) fed rabbits. ApoB-specific activities were determined in VLDL, IDL and LDL isolated from the pooled plasma of two or three rabbits per dietary group. The production rate of VLDL apoB (1.20 +/- 0.3 vs. 1.09 +/- 0.1 mg/h per kg) was similar for the two dietary groups. The fractional catabolic rate of VLDL apoB was lower for the casein group (0.15 +/- 0.03 vs. 0.23 +/- 0.01.h-1; 0.05 less than P less than 0.10). Although the pool size of VLDL apoB was higher in the casein group (8 +/- 2 vs. 5 +/- 0.3 mg/kg), this value did not reach statistical significance. For LDL apoB, the increased pool size in casein-fed rabbits (30 +/- 5 vs. 5 +/- 1 mg/kg; P less than 0.01) was associated with a decreased fractional catabolic rate (0.03 +/- 0.005 vs. 0.08 +/- 0.008.h-1; P less than 0.01) and a 2-fold increase in the production rate of LDL apoB (1 +/- 0.3 vs. 0.4 +/- 0.06 mg/kg per h; 0.05 less than P less than 0.10) compared to rabbits fed soy protein. Analysis of precursor-product relationships between the various lipoprotein fractions showed that casein-fed rabbits synthesized a higher proportion of LDL apoB (95% +/- 2 vs. 67% +/- 2; P less than 0.001) independent of VLDL catabolism. These results support the concept that the hypercholesterolemia in casein-fed rabbits is associated with impaired LDL removal consistent with a down-regulation of LDL receptors. These changes do not occur when the casein is replaced by soy protein.

Animals↗
PubMed1989

Effects of dietary casein and soy protein on metabolism of radiolabelled low density apolipoprotein B in rabbits.

Rabbits fed semipurified diets containing casein have elevated plasma cholesterol levels compared to those fed soy protein. As part of continuing studies on the mechanism of casein-induced hypercholesterolemia, two groups of six rabbits were fed these diets for 14 to 16 weeks. Animals fed the casein diet were found to have significantly higher plasma concentrations of protein, cholesterol, triacylglycerol, phospholipid and apolipoprotein B (apo B) associated with low density lipoprotein (LDL) than those fed the soy protein diet. Kinetic studies showed that the fractional catabolic rate of LDL-apo B was significantly lower in animals fed casein than in those fed soy protein regardless of whether the tracer LDL was obtained from donors fed casein or soy protein. The production rate of LDL-apo B was higher in casein-fed animals but this was not statistically significant. These results show that the efficiency of removal of LDL is significantly reduced in animals fed casein compared to those fed soy protein, and that the source of LDL did not affect the efficiency of its subsequent removal. The accumulation of LDL in casein-fed animals is consistent with down-regulation of the LDL receptor.

Animals↗
PubMed1989

Effects of cholesterol-free, semipurified diets containing different levels of casein or soy protein on distribution of cholesterol and protein among serum lipoproteins of rabbits.

Rabbits fed cholesterol-free, low-fat, semipurified diets have more cholesterol and protein in serum low density lipoprotein (LDL) relative to high density lipoprotein (HDL) than rabbits fed Chow diet. This difference was accentuated by a casein semipurified diet but was also observed with a soy protein diet even though the latter did not produce an elevation of serum cholesterol. To investigate the reason for these differences, the formulation of the semipurified diets was altered by reducing the level of protein from 27 to 16%, increasing the fat from 1 to 4% and the fiber from 5 to 13%, to correspond more closely to the proportions in Chow. With this formulation, the soy protein diet gave a lipoprotein pattern similar to that of Chow, whereas the casein diet produced a moderately elevated serum cholesterol level with more cholesterol in LDL than in HDL. When the protein in the newly formulated diets was increased back to 27%, the lipoprotein patterns reverted to those obtained with the original formula. In this case, soy protein-fed rabbits had moderately elevated serum cholesterol whereas casein-fed animals showed hypercholesterolemia. These results indicate that the altered lipoprotein pattern observed previously in rabbits fed semipurified diets is related to the high level of protein in those diets.

Animals↗
PubMed1989

Compositional changes in serum lipoproteins during developing hypercholesterolemia induced in rabbits by cholesterol-free, semipurified diets.

Changes in the concentration and composition of serum very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) were studied in rabbits transferred from chow diet to cholesterol-free, semipurified diets containing casein or isolated soy protein. The fat and fibre content of these diets was similar to that of chow but a higher protein level was used to enhance the hypercholesterolemia. During the first week on the casein diet, there was a marked increased in LDL-cholesterol, protein and phospholipids, and these higher levels were maintained during the subsequent 3 weeks of the study. Similar but less marked changes were obtained with the soy protein diet. The components of VLDL showed relatively little change after introduction of the diets to the animals. In both VLDL and LDL, the proportion of cholesterol increased and that of triglycerides decreased after 1 week on the casein diet and a similar trend was seen in HDL. The concentration of HDL-cholesterol showed little change but triglycerides, protein and phospholipids all tended to decline on both casein and soy protein diets.

Animals↗
PubMed1989

Upper limits of nutrients in infant formulas: polyunsaturated fatty acids and trans fatty acids.

As upper limits for standard infant formulas, it is suggested that n-6 fatty acids not exceed 20% of total fatty acids or 10% of total energy; that alpha-linolenic acid not exceed 3% and eicosapentaenoic and docosahexaenoic acid not exceed 1% of total fatty acids; or that the sum of these n-3 fatty acids not exceed 2% of total energy. Trans fatty acids are not recommended for use in standard infant formulas. The rationale for these recommendations is presented in each case.

Fatty Acids↗
PubMed1988

Effects of dietary fat on long-term growth and mammary tumorigenesis in female Sprague-Dawley rats given a low dose of DMBA.

The effects of dietary fat on experimental mammary cancer have typically been observed in relatively young animals. However, in human populations, breast cancer incidence and mortality are highest in postmenopausal women. To develop an animal model that stimulates the human situation more closely, female Sprague-Dawley rats were given a relatively small dose (1.5 mg) of 7,12-dimethylbenz[a]anthracene (DMBA) at 50 days of age while on a semipurified diet containing 3% sunflower-seed oil. One week later, half of the 70 rats were transferred to a diet containing 20% sunflower-seed oil. Very few mammary lesions appeared until about 35 weeks after administration of DMBA, at which time palpable mammary nodules began to appear in many of the animals on the high-fat diet. More than half of the animals in this group had developed nodules by Week 41, whereas the other half of the animals on the low-fat diet developed nodules by Week 46. Rats on the high-fat diet gradually became much more obese than those on the low-fat diet and were significantly heavier at the time they developed lesions. The incidence of nodules continued to increase in both groups and reached 100% in the group fed the high-fat diet by Week 55, with a 70% incidence of adenocarcinomas. At this time, 79% of the animals on the low-fat diet had palpable nodules without a plateau in incidence being reached. On autopsy, adenocarcinomas were found in 57% of animals on the low-fat diet.(ABSTRACT TRUNCATED AT 250 WORDS)

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

Composition of phospholipid molecular species from mammary tumors.

The molecular phospholipid species of mammary tumors induced by 7,12-dimethylbenz[a]anthracene in rats that were fed diets containing 20 or 3% sunflower-seed oil and different levels of calcium were analyzed by high-pressure liquid chromatography. Twenty-seven molecular species of phospholipids were identified. Phosphatidylcholine was predominantly composed of palmitoyl-arachidonoyl (16:0-20:4) (17-21%), palmitoyl-oleoyl (16:0-18:1) (19-21%), stearoyl-arachidonoyl (18:0-20:4) (12-13%), and 1,2-dipalmitoyl (16:0-16:0) (10-14%) species. The major molecular species of phosphatidylethanolamine were 18:0-20:4 (37-39%) and 16:0-20:4 (10-11%). The composition of diacyl phosphatidylcholine and diacyl phosphatidylethanolamine molecular species from rat mammary tumors was not greatly affected by the different diets.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1987

Extraction and quantitation of dolichol and dolichyl phosphate in soybean embryo tissue.

A procedure for the quantitative extraction of both dolichol and dolichyl phosphate (Dol-P) in plant tissue (soybean embryos) into diethyl ether from an alkaline saponification mixture is described. A complete and quantitative separation of total dolichol and total Dol-P is then obtained based on their respective solubilities in diethyl ether and water. After separation dolichol and Dol-P can both be analyzed and quantitated directly by reverse-phase HPLC on C18 columns without additional purification. The two major homologs of dolichol and Dol-P are those with 17 and 18 isoprene units. The total dolichol and total Dol-P contents of dry embryos were 96.3 +/- 0.8 and 5.3 +/- 0.1 micrograms/g, respectively. The post-HPLC recoveries for dolichol and Dol-P were 101 +/- 2 and 84 +/- 3% respectively, using [1-14C]dolichol and Dol-P containing 20 isoprene units as recovery standards. Dol-P estimations could be carried out on material equivalent to as little as 65 mg embryo tissue.

Chromatography, High Pressure Liquid↗
PubMed1987

Extraction and quantitation of total cholesterol, dolichol and dolichyl phosphate from mammalian liver.

A procedure is described for the determination of total cholesterol, dolichol and dolichyl phosphate (Dol-P) in mammalian liver. It is based on extraction of these compounds into diethyl ether after alkaline saponification of the tissue. Extractability is affected by the length of saponification and concentration of potassium hydroxide (KOH) in the saponification mixture. After extraction, total cholesterol and dolichol are quantitated directly by reverse-phase high pressure liquid chromatography (HPLC) on C18. Dol-P requires further purification before quantitation by HPLC, this is accomplished by chromatography on silicic acid. These methods gave recoveries of over 90% for cholesterol and dolichol and about 60% for Dol-P, using [4-14C]cholesterol, a polyprenol containing 15 isoprene units, and [1-14C]Dol-P as recovery standards. Concentrations of total cholesterol, dolichol and Dol-P in livers from one month-old-CBA mice were found to be 5.7 +/- 0.7 mg/g, 66.3 +/- 1.2 micrograms/g and 3.7 +/- 0.3 micrograms/g, respectively.

Animals↗
PubMed1987

Summation: which fat/how much fat--animals.

Promotion of carcinogenesis in rats by dietary fat depends on the amount and type of fatty acids ingested, mainly as triglycerides. A certain amount of essential fatty acid of the linoleate type (n-6) is required for promotion of mammary cancer and pancreatic cancer and probably also for colon cancer. Promotion is also enhanced by a high level of dietary fat, and this additional effect seems to be relatively independent of the type of fat. Saturated fatty acids, either medium or long chain, and cis and trans monoenoic fatty acids appear to have no specific promoting effects. Fish oils containing long-chain polyunsaturated fatty acids of the linolenate type (n-3) are inhibitory, and this may also be true for rapeseed oil high in erucic acid, a long-chain monoenoic fatty acid. The promoting action of dietary fat can be modified by other components of the diet, such as starch, sugar, and fiber. Promotion is also dependent on the length of time animals are exposed to the high-fat diet. The overall tumor yield can be decreased by reducing the level and degree of unsaturation of the dietary fat after a period of feeding a high polyunsaturated-fat diet.

Animals↗
PubMed1987

Dietary fat in relation to hormonal induction of mammary and prostatic carcinoma in Nb rats.

Mammary carcinoma was induced in female Nb rats by implanting pellets of estrone at 25-28 days of age, and prostatic cancer was induced in male rats of the same strain by repeatedly implanting pellets of testosterone propionate. Feeding semipurified diets containing either 3% or 20% corn oil did not significantly affect the incidence or yield of mammary tumors, although tumors tended to appear somewhat earlier in animals on the high-fat diet, confirming the report of Dunning et al. published nearly 40 years ago. The yield of prostatic tumors was too low to draw any conclusions with respect to dietary fat. Hormonally induced mammary tumors appear to be less responsive to dietary fat than those induced by commonly used chemical carcinogens.

Animals↗
PubMed1987

Absorption and distribution of [1-14C]dolichol intubated into rats.

[1-14C]Dolichol was mixed in vitro with sunflower seed oil and intubated into rats. Radioactivity began to appear in the blood at 3 h and peaked after about 6 h. The absorbed radioactivity was rapidly cleared from the blood. At 7.5 h postintubation two thirds of the radioactivity in the serum was associated with chylomicrons and about one quarter with the high density lipoproteins. At 12 h the proportion of the radioactivity in the chylomicrons had fallen to one third and that in the high density lipoproteins had increased to one half of the total. Less than 0.02% of the dose was found in the tissues after 12 h. Liver and blood each contained about one third of the total, with smaller amounts in the lungs and spleen. The heart, testes, brain, and kidneys contained only traces of radioactivity. After 12 h most of the radioactivity in the tissues and feces was present as [1-14C]dolichol. The radioactive compounds in the urine (about 0.05% of the dose) were more polar than [1-14C]dolichol as determined by thin-layer chromatography.

Animals↗