PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “DIETARY PROTEINS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1987

Relationships between dietary protein, dietary energy, rearing environment, and nutrient utilization by broiler breeder pullets.

The relationship between dietary energy and protein and their interaction with method of restriction and environment were studied. In Experiment 1, two isocaloric diets (2750 kcal/kg) formulated to contain either 13.5% or 15.5% protein were fed to broiler breeder pullets from hatching through 21 weeks of age. There were no significant differences in body weight due to dietary protein but chicks fed the 13.5% protein ration did require a significantly greater quantity of feed to produce an equivalent body weight. Sexual maturity, peak egg production, and egg size were not affected by the level of dietary protein but total egg production was significantly decreased in pullets fed the 13.5% protein diet. In Experiment 2, 2970 kcal/kg ration containing 15.5% protein was fed to pullets that were reared under two different lighting environments, natural daylength or 24 hr light for the first 7 days and 8 hr light per day thereafter. Pullets housed in the controlled environment and reared on an every-other-day restriction program had significantly improved feed utilization compared with similarly restricted birds kept under natural light. Environmental effects on feed utilization were not as great in the every day restriction treatment. Chicks exposed to natural daylight and fed 15.5% protein diets had similar caloric efficiencies (kcal/g) at 15 weeks of age in both experiments despite dietary density differences of 220 kcal/kg. This supports a hypothesis that above some minimal level of protein intake, caloric intake has the greatest control over body weight gain in restricted pullets, particularly where every-other-day feeding is used during part of the growing period.

Animal Feed↗
PubMed1988

Calcium utilization: effect of varying level and source of dietary protein.

Dietary protein exerts a significant calciuretic effect. A twofold increase in protein at constant levels of calcium and phosphorus intakes causes a 50% increase in urinary calcium. The protein-induced hypercalciuria results primarily from decreased fractional renal tubular reabsorption of calcium associated with catabolism of excess sulfur amino acids and the resultant urinary excretion of acid and sulfate. A protein-induced elevation in glomerular filtration rate also contributes to the calciuresis. Dietary phosphorus also modifies the calciuretic effect of proteins, as it increases renal tubular reabsorption of calcium and thereby exerts a hypocalciuretic effect. Consequently, a soy-based diet was able to maintain calcium balance at a calcium intake of 457 mg/day in spite of a protein intake of 90 g, presumably due to the lower level of sulfur amino acids in the soy diet and to the 1450 mg phosphorus which accompanied the soy protein.

Blood Pressure↗
PubMed1990

Digestion and absorption of dietary protein.

Dietary protein is normally assimilated in an efficient manner following the action of gastrointestinal proteases. A number of pathological conditions can alter this process, with deleterious nutritional consequences.

Adult↗
PubMed2001

Oral tolerance and gut-oriented immune response to dietary proteins.

Dietary proteins induce both a local immune response characterized by IgA production and systemic immune response characterized by the production of TH2/TH3 cytokines. By influencing the class of immune response, the gut enhances the efficacy of immunity against proteins that enter the body through the diet while, at the same time, ensuring its own safety. This article reviews and summarizes the field of "oral tolerance," with emphasis on recent advancements.

Animals↗
PubMed1974

The responses of rat intestinal brush border and cytosol peptide hydrolase activities to variation in dietary protein content: dietary regulation of intestinal peptide hydrolases.

The effects of variation in dietary protein content on small intestinal brush border and cytosol peptide hydrolase activities have been investigated. One group of rats was fed a high protein diet (55% casein) and another group was fed a low protein diet (10% casein). After 1 wk, brush border peptide hydrolase activity (L-leucyl-beta-naphthylamide as substrate) and cytosol peptide hydrolase activity (L-prolyl-L-leucine as substrate) were determined in mucosae taken from the proximal, middle, and distal small intestine. As judged by several parameters, brush border peptide hydrolase activity was significantly greater in rats fed the high protein diet when data for corresponding segments were compared. In contrast, no significant difference was seen in cytosol peptide hydrolase activity. IN A SECOND STUDY, BRUSH BORDER AND CYTOSOL PEPTIDE HYDROLASE ACTIVITIES WERE DETERMINED IN THE PROXIMAL INTESTINE BY UTILIZING AN ADDITIONAL THREE PEPTIDE SUBSTRATES: L-leucyl-L-alanine, L-phenylalanylglycine, and glycyl-L-phenylalanine. Sucrase, maltase, and alkaline phosphatase activities were also determined. As before, brush border peptide hydrolase activities were significantly greater in rats fed the high protein diet. However, activities of the nonproteolytic brush border enzymes did not vary significantly with diet. In contrast to the results obtained with L-prolyl-L-leucine as substrate for the cytosol enzymes, cytosol activity against the three additional peptide substrates was greater in rats fed the high protein diet. It is suggested that the brush border peptide hydrolase response to variation in dietary protein content represents a functional adaptation analogous to the regulation of intestinal disaccharidases by dietary carbohydrates. The implication of the differential responses of the cytosol peptide hydrolases is uncertain, since little is known of the functional role of these nonorgan-specific enzymes.

Animals↗
PubMed1993

Reduced urinary protein after dietary protein restriction instruction in proteinuric diabetic patients.

An early restriction of dietary protein intake may reduce the rate of renal function deterioration in human diabetics. This study investigates the effect of a restricted-protein diet on proteinuria in diabetic patients with persistent albuminuria after frequent dietary instruction. Twenty-six patients were divided into two groups: the restricted-protein diet (RPD) group (16 patients), who were on a diet containing 0.6-0.8 g/kg/day protein; and the normal protein diet (NPD) group (10 patients), who were on a diet containing 1.5 g/kg/day protein. Weekly dietary interview were conducted by a dietitian and a trained nurse. Of the 26 patients studied, five RPD patients and three NPD patients were dismissed. Of the 11 RPD patients who completed the study, seven patients (RPD-success) had a decreased calculated protein intake (mean value, 62 +/- 4 g/day) compared to the corresponding value (mean value, 73 +/- 5 g/day) before the study. The mean calculated protein intake value in the RPD-success group was higher than the protein content (42 +/- 1 g/day) prescribed for them; however, that of the NPD group, did not significantly differ before and at the end of the study. The RPD-success group's daily urinary protein excretion showed a significant reduction, with a mean value before (1378 +/- 414 mg/day) and after (880 +/- 413 mg/day) 3.7 +/- 0.4 months dietary protein restriction. In contrast, the daily protein loss in the NPD group was insignificant (1300 +/- 443 to 2976 +/- 862 mg/day) after 3.3 +/- 0.6 months dietary instruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Albuminuria↗
PubMed2001

Characterization of binding between the rat small intestinal brush-border membrane and dietary proteins in the sensory mechanism of luminal dietary proteins.

Dietary proteins are recognized by the gastrointestinal tract to display physiological functions, however, the sensory mechanism of the intestinal mucosa is not known. We examined binding properties between the rat small intestinal brush-border membrane (BBM) and proteins by using a surface plasmon resonance biosensor. BBM and solubilized BBM prepared from the rat jejunum bound to casein immobilized on the sensor surface, but not to bovine serum albumin. The ileal BBM showed less binding to casein than the jejunal BBM. Solubilized BBM binding to immobilized alpha-casein was slightly inhibited by aminopeptidase inhibitors, but still more inhibited by addition of casein with the inhibitors. Guanidinated casein inhibited the solubilized BBM binding to alpha-casein more strongly than casein (casein sodium and alpha-casein) inhibited. Trypsinization of solubilized BBM abolished its binding activity to alpha-casein. These results indicate that some membrane protein, but not aminopeptidases, contained in BBM interacts with dietary proteins, and that guanidinated casein has a higher affinity for BBM than intact casein. These binding intensities for proteins were closely correlated to physiological responsiveness, and are possibly involved in a sensory system for dietary protein in the intestine.

Aminopeptidases↗
PubMedDate not supplied

[Adaptation of renewal of rat liver proteins to dietary protein with low biological value].

The study of the dynamics of adaptation to the rations containing casein and wheat protein showed some accumulation of hepatic protein on days 4-9. Evaluation of 14C-Leucine and protein turnover from the kinetics of precursor elimination from the pool and that of incorporation into proteins, demonstrated that there were no significant differences in the rate of endogenous protein synthesis, and the higher protein levels are associated with the lower secretion of these export proteins from the liver. In another experiment after adaptation to the casein feed, the animals were fed a wheat protein-containing feed, there were no changes in protein levels, yet the rate of total liver protein turnover was significantly increased on day 5, as shown by massive label estimation and calculation using the modified equation. Adaptation to new rations is accompanied by the initial accumulation of protein in the liver tissue and the subsequent adaptation to proteins of low biological value may be related to increases in the turnover of blood proteins exported from liver tissue.

Adaptation, Physiological↗
PubMed1990

High dietary protein regimens provide significant protection from mercury nephrotoxicity in rats.

The effects of high protein dietary regimens prior to the administration of inorganic mercury were investigated. Male Sprague-Dawley rats were pair-fed on purified test diets containing either normal (20%) or high (60%) concentrations of protein. Mercury was administered as a single intravenous injection of mercuric chloride (1 mg/kg). All rats maintained on normal dietary protein prior to and following mercury injection exhibited severe kidney dysfunction, extensive necrosis of both second (S2) and third (S3) segments of the kidney proximal tubules, and 100% mortality. In contrast, rats maintained on high dietary protein for 48 hr or longer just prior to mercury injection and returned to normal dietary protein immediately following mercury administration all survived and exhibited normal serum creatinine and BUN values within 4 days following mercury administration. The kidneys of this latter group took up significantly less radiolabeled mercury during the first 12 hr following mercury injection, and exhibited relatively little damage to the second segments (S2) of the proximal tubules. The third segments (S3) of the proximal tubules, however, exhibited the same degree of necrosis as that observed in the control group. Maintaining rats on high dietary protein regimens for shorter periods of time prior to mercury infusion (i.e., 12 or 24 hr) also dramatically reduced subsequent acute renal failure and improved survival, although not to the extent noted following 48 hr or longer on these diets. These observations suggested that high dietary protein regimens may protect from mercury nephrotoxicity by reducing mercury uptake to the second segments (S2) of the proximal tubules during the initial period of exposure to intravenously administered mercury.

Animals↗
PubMed2001

Effect of increased dietary protein and decreased dietary carbohydrate on performance and body composition in racing Greyhounds.

OBJECTIVE: To determine effects of increased dietary protein and decreased dietary carbohydrate on hematologic variables, body composition, and racing performance in Greyhounds. ANIMALS: 8 adult Greyhounds. PROCEDURE: Dogs were fed a high-protein (HP; 37% metabolizable-energy [ME] protein, 33% ME fat, 30% ME carbohydrate) or moderate-protein (MP; 24% ME protein, 33% ME fat, 43% ME carbohydrate) extruded diet for 11 weeks. Dogs subsequently were fed the other diet for 11 weeks (crossover design). Dogs raced a distance of 500 m twice weekly. Rectal temperature, hematologic variables before and after racing, plasma volume, total body water, body weight, average weekly food intake, and race times were measured at the end of each diet period. RESULTS: When dogs were fed the MP diet, compared with the HP diet, values (mean +/- SD) differed significantly for race time (32.43 +/- 0.48 vs 32.61 +/- 0.50 seconds), body weight (32.8 +/- 2.5 vs 32.2 +/- 2.9 kg), Hct before (56 +/- 4 vs 54 +/- 6%) and after (67 +/- 3 vs 64 +/- 8%) racing, and glucose (131 +/- 16 vs 151 +/- 27 mg/dl) and triglyceride (128 +/- 17 vs 104 +/- 28 mg/dl) concentrations after racing. CONCLUSIONS AND CLINICAL RELEVANCE: Greyhounds were 0.18 seconds slower (equivalent to 0.08 m/s or 2.6 m) over a distance of 500 m when fed a diet with increased protein and decreased carbohydrate. Improved performance attributed to feeding meat to racing Greyhounds apparently is not attributable to increased dietary protein and decreased dietary carbohydrate.

Animal Feed↗
PubMed1991

Ineffectiveness of dietary protein augmentation in the management of the nephrotic syndrome.

The nephrotic syndrome is a consequence of altered permselectivity of the glomerular basement membrane resulting in urinary losses of albumin and other serum proteins. Although dietary protein augmentation increases albumin synthesis, it has not been shown to increase serum albumin or muscle protein. Dietary protein was increased from 8.5% to 21% in pair-fed rats with Heymann nephritis and resulted in an increase both in albumin synthesis and urinary albumin excretion, but not in serum albumin concentration or in total albumin pools. The increase in dietary protein was 8 times greater than the resulting increase in urinary protein excretion, but nearly all of the additional ingested protein was catabolized to urea and excreted in the urine rather than used to augment growth. Dietary supplementation with protein has no obvious beneficial effect on nutritional status of nephrotic rats.

Albumins↗
PubMed1994

Effect of clenbuterol on recovery of muscle mass and carcass protein content following dietary protein depletion in young and old rats.

There is a need for new therapeutic agents designed to prevent or restore skeletal muscle loss in frail, elderly subjects resulting from injury or disease and associated catabolic stresses such as malnutrition. Since the beta 2-adrenergic agonist clenbuterol increases skeletal muscle mass in rats, the effect of this agent on recovery of muscle mass and carcass protein content following protein malnutrition was studied in young and old rats. The 3-week period of severe dietary protein restriction reduced body weight 21%, hind-limb muscle weight 24 and 15%, and carcass protein content 31 and 19%, respectively, in 3- and 24-month-old rats. During the 3-week recovery period induced by feeding a complete diet, 10 mg clenbuterol per kg diet increased hind-limb muscle weight 34 and 30% and carcass protein content 27 and 25%, respectively, in 3- and 24-month-old rats. Restoration was complete in animals of both ages fed clenbuterol and incomplete in animals fed the control diet. These observations suggest that clenbuterol or similar beta 2-adrenergic agonists may be useful in hastening the recovery of muscle mass and body protein stores lost because of malnutrition in frail, elderly humans.

Aging↗
PubMed1987

Influence of dietary protein on motor fluctuations in Parkinson's disease.

On a nearly zero protein diet, 11 patients with Parkinson's disease with the "on-off" effect demonstrated great sensitivity to levodopa (L-dopa)-carbidopa and reduced fluctuations. Eight patients required a 41% reduction in total L-dopa dosage and discontinuation of all adjuvant therapy to reduce the preponderance of chorea. On a high-protein diet, all patients were immobilized by bradykinesia for most of the day. A low-protein dietary regimen during the daytime offers an important technique for the control of fluctuations in patients with Parkinson's disease who are receiving L-dopa-carbidopa.

Aged↗
PubMed1991

Evidence that pretranslational and translational defects decrease serum insulin-like growth factor-I concentrations during dietary protein restriction.

Dietary protein restriction causes GH resistance and decreases serum insulin-like growth factor-I (IGF-I) concentrations. To determine whether pretranslational or translational defects are involved in the decline of serum IGF-I concentrations during protein restriction, we measured hepatic IGF-I mRNA abundance together with the serum IGF-I peptide response to exogenous GH after 1 week of protein restriction (5% casein in diet; P5) in hypophysectomized rats. We compared these responses with those of hypophysectomized rats fed a protein-sufficient diet (15% casein in diet; P15) and given exogenous GH. A single injection of rat GH (200 micrograms/100 g BW) produced a comparable IGF-I mRNA increment in both groups (at 6 h, 7.8 +/- 1.1 arbitrary units in P5 vs. 8.2 +/- 1.1 in P15), but failed to raise serum IGF-I normally in the P5 group (at 6 h, 90 +/- 15 ng/ml in P5 vs. 216 +/- 63 in P15; P less than 0.01). The post-GH decline of the 7.5-kilobase (kb) IGF-I mRNA abundance was faster in P5 than in P15 animals. In another experiment in intact rats subjected to protein restriction, injections of pharmacological doses of rat GH (400 micrograms/100 g BW.day) for 1 week restored liver IGF-I mRNA abundance to normal without normalization of serum IGF-I (403 +/- 91 vs. 713 +/- 53 ng/ml; P less than 0.01). Our data suggest that 1) the machinery involved in the transcription of the liver IGF-I gene is intact in protein-restricted rats, because these animals retain the ability to muster normal IGF-I mRNA responses to high doses of exogenous GH; 2) the stability of the 7.5-kb IGF-I mRNA is probably decreased by the protein restriction, as suggested by the faster decline of the 7.5-kb transcript in P5 than in P15 hypophysectomized rats; and 3) the discrepancy between normal liver IGF-I mRNA abundance and low serum and liver IGF-I peptide concentrations suggests that translational stalling of the IGF-I mRNAs or increased serum IGF-I clearance is involved in the low serum IGF-I concentrations during dietary protein restriction.

Animals↗