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PubMed2003

The Diet Quality Index-International (DQI-I) provides an effective tool for cross-national comparison of diet quality as illustrated by China and the United States.

A composite measure of diet has been preferred to an index of a single nutrient or food in the area of dietary assessment. However, the lack of such a tool for cross-national comparisons has restricted the ability to compare diet quality between countries using an overall measure of diet. In this study, we created a tool called the Diet Quality Index-International (DQI-I) for global monitoring and exploration of diet quality across countries. The major categories of the index components are variety, adequacy, moderation and overall balance. Using the tool, this research presents a cross-national comparison of diet quality between China and the United States, incorporating comparable national in-depth diet data. The mean of the DQI-I score was slightly higher in China than in the United States. By major categories of the DQI-I, dietary variety was better achieved in the U.S. diet; moderation and overall balance of intakes were better accomplished in China. The DQI-I was successful in capturing variability in intakes of food and nutrients in both countries. Some distinct patterns of poor quality diet in each country were also identified. As demonstrated in this study, the DQI-I provides an effective means of cross-national comparative work for global understanding of diet quality. Furthermore, the dietary problem areas identified by the DQI-I may be useful in guiding the development of programs to improve public health.

China↗

PubMed1976

Variations in the response of the thyroid gland of the rat to different low-iodine diets: correlation with iodine content of diet.

Large variations are frequently encountered in the thyroidal responses of rats to commercially available low-iodine diets. The major aim of this investigation was to attempt to correlate these variations with differences in the iodine content of the diets. A method was developed for measuring the iodine content of low-iodine diets which was sufficiently sensitive to discriminate between a diet containing 15-20 ng of iodine per g and one containing 30-40 ng of iodine per g. Large differences were observed between various commercial low-iodine diets in their ability to induce goiter and to affect other indices of thyroid function, and these differences could be correlated with differences in the iodine content. The most severe iodine deficiency occurred in rats that were fed a Remington diet containing 15-20 ng of iodine per g. After 3 months on this diet, thyroid weight increased about 7-fold, thyroid 127I concentration was reduced to about 0.5% of control values, serum thyroxine (T4) was reduced to less than 0.25 mug/100 ml, the ratio of labeled triiodothyronine to labeled T4 was increased to 5.2, and that of labeled monoiodotyrosine to labeled diiodotyrosine was increased to 4.2. Much smaller changes were observed in the rats on the other low-iodine diets, which ranged from 30-40 to about 100 ng of iodine per g. A daily supplement of only 0.2 mug of iodide per day administered to rats on a Remington low-iodine diet produced a significant changes in thyroidal responses. These results suggest that iodine deficiency alone is sufficient to explain the effects of the Remington low-iodine diet and that it is not necessary to postulate the presence of a goitrogen.

Animals↗

PubMed2002

Body composition and tissue accretion rates of barrows fed corn-soybean meal diets or low-protein, amino acid-supplemented diets at different feeding levels.

Two experiments, each with 39 high-lean-gain potential barrows, were conducted to evaluate the organ weights, body chemical composition, and tissue accretion rates of pigs fed corn-soybean meal diets (CONTROL) and low-protein diets supplemented with crystalline lysine, threonine, tryptophan, and methionine either on an ideal protein basis (IDEAL) or in a pattern similar to that of the control diet (AACON). Amino acids were added on a true ileally digestible basis. The initial and final BW were, respectively, 31.5 and 82.3 kg in Exp. 1 and 32.7 and 57.1 kg in Exp. 2, and pigs were fed for 55 and 27 d in Exp. 1 and 2, respectively. In Exp. 1, the CONTROL and IDEAL diets were offered on an ad libitum basis, or by feeding 90 or 80% of ad libitum intake. In Exp. 2, the CONTROL, IDEAL, and AACON diets were offered on an ad libitum basis, or by feeding 80% of the ad libitum intake. Three pigs were killed at the start of the experiments and three from each treatment were killed at the end of each experiment to determine body chemical composition. In both trials, the whole-body protein concentration (g/kg) and the accretion rates of protein (g/d) were greater (P < 0.05) for pigs fed the CONTROL than for pigs fed the IDEAL and AACON diets. In Exp. 1, pigs fed the CONTROL diet had a trend (P < 0.10) for greater water and lower lipid concentration and had greater (P < 0.05) water and ash accretion rates. Whole-body protein concentration was greatest (P < 0.05) in pigs fed at 80% of ad libitum, but protein, water, and ash accretion rates were greatest (P < 0.05) in pigs allowed ad libitum access to feed. In summary, pigs fed the IDEAL and the AACON diets had less protein in the body and lower protein accretion rates than pigs fed the CONTROL diet. It seems that reductions in protein deposition in pigs fed the IDEAL and AACON diets may have been due to a deficiency of one or more essential amino acids or possibly to increases in the NE for metabolic processes leading to increases in adipose tissue deposition.

Amino Acids↗

PubMed1987

Effects of restricted diet on protein metabolism measured by [15N]glycine in high-fat-diet-induced obese rats.

The effect of restricted diets on protein metabolism was studied in obese rats (obesity had been induced by ad libitum feeding of a diet containing 30% fat and 25% casein). The obese rats were fed on one of three restricted diets, each containing 5% fat, for 2 weeks (restricted feeding groups); a high-protein diet (HPD, 50% casein), a standard-protein diet (SPD, 25% casein), or a low-protein diet (LPD, 5% casein). The food intake was restricted to 5 g per day per rat. On the eleventh day, the rats were given [15N]glycine orally, and 4 days later, they were killed. The restricted feeding groups all showed similar weight losses (about 100 g), 2 weeks after the start of the restricted diet. The 15N distribution in whole body was measured and results were compared with those of control rats given 5%- or 30%-fat diet ad libitum. The whole-body distribution of 15N in the HPD group was similar to that in the rats fed ad libitum although the diet intake was restricted. The results suggested that the amount of protein in a restricted diet is important for maintenance of protein metabolism in obese rats.

Animals↗

PubMed1999

[The Mediterranean diet improves the profile of male smokers compared with the diet recommended by the American Cholesterol Program (NCEP-I)].

BACKGROUND: A study of the effect of smokers' diets on their atherogenic lipidic profile. SUBJECTS AND METHODS: 41 healthy males (32 non-smokers and 9 smokers) consumed consecutively a diet low in fat and rich in carbohydrates (28% total fat content < 10% saturated fats, and 57% carbohydrates), and a diet rich in monounsaturated fatty acids (38% total fat content with 22% monounsaturated fats). At the end of each dietary period, adhesion was confirmed by quantification of LDL cholesterol esters, plasma lipids and insulin levels. RESULTS: There were no significant differences between the age or the body mass of the groups of smokers or non-smokers. After both diets tobacco was found to have a significant effect on triglyceride levels (p < 0.0007), HDLc (p < 0.007), apo A-I (p < 0.02) and the LDLc/HDLc ratio (p < 0.005), revealing an interaction between diet and both HDLc levels (p < 0.004) and LDLc/HDLc ratios (p < 0.003). With the low fat and high monounsaturated fatty acid content diets smokers presented higher triglyceride levels (both with p < 0.0002) and LDLc/HDLc ratios (p < 0.0002 and p < 0.05, respectively) and lower levels of apo A-I (p < 0.002 and p < 0.004, respectively). However, in smokers the HDLc levels were only reduced after the low fat diet (p < 0.0003) and after the diet with a high monounsaturated fat content there was a rise in HDLc levels (p < 0.02) and a drop in the LDLc/HDLc ratio (p < 0.005) compared to the group of non-smokers. There were no significant differences in the insulin levels between groups. CONCLUSION: The atherogenic lipidic profile of smokers is due to an effect of tobacco on the lipidic metabolism. This atherogenic profile is accentuated with a low fat diet rich in carbohydrates and can be rectified to some degree with a diet with a high monounsaturated fatty acid content.

Adult↗

PubMed2005

Fad diets and obesity--Part IV: Low-carbohydrate vs. low-fat diets.

The first three parts of this series of articles covered the basics of some of the more popular low-carbohydrate diets, and the theories behind them. In the fourth and final part of this series, some of the more popular low-fat and low-calorie diets, such as the Ornish diet and Weight Watchers, are covered briefly. Recently, several clinical trials of longer duration that compared low-carbohydrate versus low-fat diets have been published. These studies demonstrate that some of the low-carbohydrate diets result in reduced weight in the short-term, but their ability to reduce weight long-term any better than low-fat or other diets has been questioned. Most popular or fad diets have some positive messages contained within them and some preliminary positive short-term results, but overall the compliance rates with any fad diet are very poor over the long-term. The decision to go on any diet should be made with a health professional who can monitor the patient closely.

Body Mass Index↗

PubMed1986

Changes in lipids in liver and serum of rats fed a histidine-excess diet or cholesterol-supplemented diets.

The influence of dietary excess (5%) L-histidine on serum and liver lipids was examined in rats. Feeding a histidine-excess diet for 3, 6, 14 or 30 days caused growth retardation, hepatomegaly and decreased liver lipids throughout the period of the experiment. Hypercholesterolemia was observed after feeding a histidine-excess diet for 6 days; then serum cholesterol continuously increased for 30 days. Serum triglyceride on day 30 in rats fed the histidine-excess diet showed a significant decrease compared to rats fed the basal diet. Serum phospholipids of rats fed the histidine-excess diet for 7 or 14 days showed a significant increase compared to rats fed the basal diet. When rats were fed a basal, histidine-excess or cholesterol-supplemented diet (0.5% and 1.0% cholesterol) for 6 days, the distribution of serum high density (HDL), low density (LDL) and very low density lipoprotein cholesterol in rats fed the histidine-excess diet was similar to that of rats fed the basal diet, whereas LDL-cholesterol increased and HDL-cholesterol decreased in rats fed the cholesterol-supplemented diet.

Animals↗

PubMed1996

Gene expression of insulin signal-transduction pathway intermediates is lower in rats fed a beef tallow diet than in rats fed a safflower oil diet.

To elucidate the effects of dietary fatty acid composition on the insulin signaling pathway, we measured the gene expression of the earliest steps in the insulin action pathway in skeletal muscle of rats fed a safflower oil diet or a beef tallow diet. Rats were meal-fed an isoenergetic diet based on either safflower oil or beef tallow for 8 weeks. Both diets provided 45%, 35%, and 20% of energy as fat, carbohydrate, and protein, respectively. Insulin resistance, assessed from the diurnal rhythm of plasma glucose and insulin and the oral glucose tolerance test (OGTT), developed in rats fed a beef tallow diet. Body fat content was greater in rats fed a beef tallow diet versus a safflower oil diet. The level of insulin receptor mRNA, relative expression of the insulin receptor mRNA isoforms, and receptor protein were not affected by the composition of dietary fatty acids. The abundance of insulin receptor substrate-1 (IRS-1) and phosphatidylinositol (PI) 3-kinase mRNA and protein was significantly lower in rats fed a beef tallow diet versus a safflower oil diet. We conclude that long-term feeding of a high-fat diet with saturated fatty acids induces decrease in IRS-1 and PI 3-kinase mRNA and protein levels, causing insulin resistance in skeletal muscle.

Actins↗

PubMed2002

A low-fat diet has a higher potential than energy restriction to improve high-fat diet-induced insulin resistance in mice.

Previous studies have shown that energy restriction (ER) or low-fat (LF) diets have beneficial effects on high-fat (HF) diet-induced obesity and non-insulin-dependent diabetes. However, comparison between ER and low-fat diet regarding the effect on insulin resistance and lipid metabolism has not been reported. After inducing insulin resistance by HF feeding for 20 weeks, male C57BL/6J mice were divided into 3 groups. For a period of 12 weeks, group 1 received energy restriction (70% of ad libitum, HF diet), group 2 LF diet, and group 3 maintained on HF diet. Body weight and energy intake were reduced equally in ER and LF feeding. Plasma insulin levels were decreased on LF feeding, but were unchanged on ER, when compared with HF feeding. Glucose tolerance and insulin sensitivity tests revealed that insulin sensitivity was improved more efficiently by LF feeding than on ER. Plasma triglyceride (TG) levels were lower on LF feeding compared with ER and HF feeding. Measurement of hepatic very low-density lipoprotein (VLDL)-TG production revealed a lower production after LF diet feeding or ER compared with HF diet feeding. In summary, our data show that LF diet has a higher potential than ER to improve HF diet-induced insulin resistance, and that there is an association between improvement of insulin resistance and decrease of TG levels.

Animals↗

PubMed1998

Strategies to improve the nutritive value of rice bran in poultry diets. II. Changes in oil digestibility, metabolisable energy and attempts to increase the digestibility of the oil fraction in the diets of chickens and ducklings.

1. In experiment 1, the effects of age on oil digestibility and apparent metabolisable energy (AME) were measured in chickens and ducklings between 3 and 28 d of age on a diet with 400 g rice bran/kg. In experiment 2, a biosurfactant and a food lipase were added to diets of chickens containing 200 and 400 g rice bran/kg. In experiment 3, chicken diets containing 0 or 400 g rice bran/kg were supplemented with a food lipase (2 concentrations) or a food enzyme or their combination. 2. In experiment 1, oil metabolisability and AME increased substantially as chickens aged. Oil metabolisability was much higher in ducklings, when comparisons were made with chickens of similar age. 3. In experiment 2, lipase or biosurfactant gave no improvement in bird performance. Growth rate and food conversion ratio were, respectively, 23% and 10% better on diets with 200 compared to 400 g rice bran/kg. 4. In experiment 3, there was a significant growth response to lipase plus the enzyme mixture on the diet with 200 g rice bran/kg. On the diet with 400 g rice bran/kg, growth improvement was seen with the enzyme mixture only. 5. In experiment 3, enzyme addition did not increase oil metabolisability or AME. At 4 to 8 d of age AME was higher on the diet without rice bran but oil metabolisability was the same as on the diet with rice bran. At 19 to 23 d of age AME was similar but oil metabolisability was higher on the diet with rice bran than without. Droppings' dry matter was higher on diets without than with rice bran (32.4 vs 27.1%). 6. The response to lipase and the combination of this and a food enzyme suggest that there may be benefit in examining this interaction further although they had no effect on oil metabolisability or on AME. It is concluded that a stable AME for rice bran cannot be provided for chickens until at least 21 d of age.

Aging↗

PubMed1989

Dietary fiber content of a simulated American diet and selected research diets.

Few studies accurately report total-dietary-fiber (TDF) content of current and alternative diets. In this study we analyzed and calculated TDF content of a simulated American diet with household Nationwide Food Consumption Survey data. We also analyzed the fiber content of four research diets: control; bean; high fiber, maintenance (HFM); and high carbohydrate, high fiber (HCF). Analyzed and calculated fiber values for the simulated diet were similar. The simulated, control, bean, HFM, and HCF diets provided 5.6, 8.1, 12.2, 17.4, and 22.8 g TDF/1000 kcal, respectively. Soluble-fiber content ranged from 1.7 g/1000 kcal for the simulated diet to 6.1 g/1000 kcal for the HCF diet. Cereal products contributed the most to total fiber content of the simulated diet, followed in order by vegetables, legumes, fruits, and miscellaneous foods. Fiber content of the simulated diet was below recommended levels. The HFM diet is suggested for individuals desiring to increase their dietary fiber intake.

Dietary Fiber↗

PubMed1998

The effects of a high fat diet on leptin mRNA, serum leptin and the response to leptin are not altered in a rat strain susceptible to high fat diet-induced obesity.

Osborne-Mendel (OM) and S5B/Pl rats differ in their sensitivity to develop obesity when fed a high fat (HF) diet; OM rats become obese, whereas S5B/Pl rats remain thin. We have investigated the possibilities that either an impaired leptin response or resistance to leptin action underlies the sensitivity to this form of obesity in OM rats. In Experiment 1, OM and S5B/Pl rats fed a nonpurified diet were killed at d 0 or were fed either a HF (56% fat energy) or a low fat (LF, 10% fat energy) diet for 2 or 7 d. The HF diet increased serum leptin significantly by d 2 to levels that were similar in both rat strains. At 7 d, leptin levels were lower than at d 2 but remained higher than levels in the d 0 control groups. The leptin mRNA:18S RNA ratio in epididymal adipose tissue increased to higher levels in HF-fed OM rats than in S5B/Pl rats fed that diet. However, although the LF diet had no effect in S5B/Pl rats, it increased leptin mRNA levels in epididymal adipose tissue of OM rats compared with the controls fed the nonpurified diet. In Experiment 2, OM and S5B/Pl rats were fed HF or LF diets for 5 wk. At that time, their feeding response to a range of leptin doses (0, 1, 5 or 10 microgram) given intracerebroventricularly was tested after overnight food deprivation. There was a similar dose-dependent reduction in energy intake in response to leptin in both OM and S5B/Pl rats. These responses were independent of the diet. The data suggest that the susceptibility of OM rats to HF diet-induced obesity is not related to either a loss of central sensitivity to leptin or a failure to enhance leptin production acutely, although the failure to maintain chronically increased levels of serum leptin could contribute to the obesity.

Adipose Tissue↗

PubMedDate not supplied

Elemental diet composition and the structure and function of rat small intestine: comparison of the effects of two diets on morphology and in vivo absorption of water.

The effects of feeding elemental diets on small bowel structure and function in normal rats has been investigated, and two commercial diets Vivonex (#1) and Flexical (#2) compared. Rats were fed Diet #1 (n = 12) or Diet #2 (n = 12) for 1 month and jejunal and ileal histology compared with that of an equal number of rats fed on a normal pelleted diet. Diets #1 and #2 significantly increased villus height and decreased crypt height to villus height ratio in both jejunum and ileum (p less than 0.02 in all cases). Crypt height was also significantly reduced in the ileum but not jejunum by both elemental diets (p less than 0.05 in both cases). Segments of jejunum or ileum were perfused by an in vivo technique and water absorption measured to assess small bowel function. No significant difference in absorption was found between the rats fed Diet #1 and controls but absorption of water was depressed in both jejunum and ileum of those fed Diet #2. Small intestinal absorptive function is thus influenced by the composition of the elemental diet.

Amino Acids↗

PubMed2000

Suppression of altered hepatic foci development by a high fish oil diet compared with a high corn oil diet in rats.

Effects of low corn oil, high corn oil, and high fish oil diets on altered hepatic foci development in female Sprague-Dawley rats were investigated. Rats assigned to Groups 1-4 were initiated with saline as the control and those assigned to Groups 5-7 were initiated with diethylnitrosamine (DEN 15 mg/kg) at 24 hours of age. After weaning, all rats, except those in Group 1, received 500 ppm phenobarbital (PB) in their diet as tumor promoter for three months. Altered hepatic foci development was significantly lower in DEN-initiated rats fed the high fish oil + PB diet than in DEN-initiated rats fed the high corn oil + PB diets. Liver weight and relative liver weight were significantly greater in rats fed the high fish oil + PB diet than in rats fed the other diets, and hepatic biotransformation/detoxification enzyme activities were greater in rats fed the fish oil + PB diets than in rats fed the other diets. These results suggest that the effect of a high fish oil diet on altered hepatic foci may occur through regulation of hepatic biotransformation/detoxification enzyme activities, leading to alteration in the tumor-promoting action of PB. Dietary lipid significantly affected the hepatic phospholipid fatty acid composition of rats. n-3 polyunsaturated fatty acids were incorporated into membrane phospholipid at the expense of n-6 polyunsaturated fatty acids. A high fish oil diet caused greater oxidative stress in rats, as measured by plasma vitamin E level, red blood cell glutathione status, liver lipid peroxidation, and hepatic glutathione reductase activity. Pearson's correlation analysis indicated that the foci number was negatively correlated to the liver thiobarbituric acid-reactive substance and 7-pentoxyresorufin O-dealkylase activity, and the foci area was negatively correlated to the liver thiobarbituric acid-reactive substance activity (p < 0.05) in rats of groups that developed foci. These results suggest that the type of dietary lipid is the more important determinant for gamma-glutamyl transpeptidase-positive foci development than the amount of dietary lipid when rats consumed approximately the same amount of calories in all the dietary groups, and the underlying mechanisms may be partially ascribed to the antioxidant/oxidation status and biotransformation/detoxification system of rats.

Animals↗

PubMed2000

Effect of high-oil corn on growth performance, diet digestibility, and energy content of finishing diets fed to beef cattle.

Sixty crossbred beef steers (initial BW = 412 kg) were used in a 83-d finishing study to determine the effect of feeding dry rolled high-oil corn on performance and total-tract digestibility of finishing diets. Steers were allotted by weight to the following dietary treatments: 1) control corn (C; 82% normal corn, 12% triticale silage), 2) high-oil corn (HO; 82% high-oil corn, 12% silage), and 3) high-oil corn formulated to be isocaloric to C (ISO; 74% high-oil corn, 20% silage). Total lipid content was 4.9% (DM basis) for normal corn and 7.0% for high-oil corn. Steers were individually fed using electronic gates. Quantity of feed offered and refused was recorded daily. Fecal samples were collected on d 63 to 66 of the trial to determine digestibility. Chromic oxide was fed as an indigestible marker for 7 d before fecal collection began. Planned contrasts of HO vs C and ISO vs C were used to assess treatment differences. Dry matter intake was greater for steers fed C vs HO (P < 0.01) or C vs ISO (P < 0.01), but daily gain and feed efficiency were not affected (P > 0.05) by treatments. Digestibility of DM, OM, starch, and GE was greater (P < 0.05) for the HO diet than the C diet, but lipid digestibility did not differ among treatments (P > 0.05). The combined effect of greater GE content and digestibility resulted in greater (P < 0.01) DE content for the HO than for the C diet. Calculated DE of the corn was 8.3% greater (3.74 Mcal/kg; P < 0.01) for the HO diet and 6.5% greater (3.67 Mcal/kg; P < 0.01) for the ISO diet than the corn in the C diet (3.25 Mcal/kg). Dry matter and GE digestibility did not differ (P > 0.05) between the C and ISO diets. Steers consuming ISO had greater (P < 0.05) starch digestibility than steers fed the C diet. Although HO had higher DE, DE intake was similar (P > 0.05) for HO and C due to lower DMI for HO. These results indicate that available energy is greater from high-oil corn than from typical corn, but depressed voluntary feed intake prevented performance improvements and resulted in equal energy intakes between high-oil corn and typical corn diets.

Animal Feed↗

PubMed1979

Effect of low protein diets on free amino acids in plasma of young men: effect of wheat gluten diet.

Studies were made on alterations in plasma amino acids in young men fed a diet containing graded levels of wheat gluten. After one week on a standard diet containing 200 mgN/kg of mixed protein (animal protein content 45%), 38 young men were given a wheat gluten diet containing 170, 100, 60, 30, 15 or zero mgN/kg for 2 weeks. Blood samples measuring plasma free amino acids were taken before breakfast at the end of the periods on a standard diet and an experimental diet. In subjects on diets containing 170 to 30 mgN/kg the plasma concentrations of threonine, valine, methionine, leucine, tyrosine, phenylalanine, serine, histidine and arginine fell significantly with decrease in protein intake, but the concentration of alanine increased significantly. On the other hand, in subjects on diets containing 15 or zero mgN/kg, the plasma concentrations of the essential amino acids did not decrease, but increased to slightly more than in subjects on a diet containing 30 mgN/kg, and the alanine and glycine concentrations increased steadily. Values for plasma lysine varied from 146 +/- 22 to 194 +/- 31 mumoles/liter with gluten intakes of 170 to zero mgN/kg, but were comparable with that of 186 +/- 33 mumules/liter in subjects on a standard diet, showing that the plasma lysine concentration did not clearly reflect the dietary concentration of lysine in young men on a wheat gluten diet.

Adult↗

PubMed2001

Diet restriction in rat toxicity studies: automated gravimetric dispensing equipment for allocating daily rations of powdered rodent diet into pouches and 7-day feeders.

Survival of ad libitum-fed rats has declined in the 2-year carcinogenicity bioassay. Restriction of the number of calories, without compromise of the overall nutrition offered to animals including rats, results in increased lifespan of animals. Diet restriction in rats is best achieved through offering of rations of feed daily instead of weekly, as is routinely done in ad libitum studies. The objective of this project was to develop an accurate and precise method of dispensing daily rations of feed. A gravimetric vibratory-type dispenser was used to dispense target weights of 15 and 20 g of powdered certified rodent diet into either labeled pouches or seven-well carousel feeders. The tolerance of the dispenser was the target weight +/- 3%. The amount of food offered to the diet-restricted rats was approximately 25% lower than that consumed by rats offered diet ad libitum. After 2 years, male rats offered 20 g and female rats offered 15 g of powdered rodent diet daily had remarkably lower body weights than did animals offered the diet ad libitum. Generally, the rats ate the entire ration of food offered to them each day. Survival of the diet-restricted rats was 70% to 82% at the end of a 2-year study. This investigation demonstrates that modest reduction of food intake, resulting in increased survival of Sprague Dawley rats in 2-year carcinogenicity bioassays, can be achieved reliably and efficiently through use of an accurate and precise automated method of dispensing powdered diet for use in multiple rat studies. In addition, this method of food dispensing provides a practical way to administer test compound in the diet under the conditions of diet restriction.

Animal Feed↗

PubMed1977

A comparison of insulin binding by liver plasma membranes of rats fed a high glucose diet or a high fat diet.

The interaction of (125)I-labeled insulin with purified liver plasma membrane from rats fed a high fat (L) diet or a high glucose (G) diet was studied with respect to specific binding, insulin degradation, binding site degradation, and rate of hormone association and dissociation. Scatchard analysis suggested the presence of high and low affinity binding sites for membranes of both G and L diet-adapted rats. However, liver plasma membrane from rats fed the high glucose diet bound 50% more insulin than did membrane from rats fed the high fat diet. Diet did not change insulin binding site degradation. The results suggested that an apparently reduced number of insulin binding sites (G = 10.2 +/- 2.45 x 10(-12) mol/mg membrane protein, L = 4.5 +/- 1.73 x 10(-12) mol/mg membrane protein) associated with fat feeding as compared to glucose feeding was responsible for the reduced insulin binding by membrane from rats fed the high fat diet. The effects of concanavalin A (Con A) on insulin binding to liver plasma membranes were also investigated. Con A enhanced the specific binding of insulin to liver plasma membranes from rats fed either diet at concentrations lower than 50 micro g/ml, whereas at concentrations higher than 50 micro g/ml Con A inhibited insulin binding to these membranes. The stimulatory effect of Con A on insulin binding at low concentrations was greater and inhibition of binding at high concentration was less in the case of membrane prepared from L diet-adapted animals. These results suggested that diet can modify the plasma membrane glycoproteins.

Animals↗