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Results for “DIETARY PROTEINS”

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At least 217 records · Page 12Linked to original sources

PubMed1992

The morphological and biochemical changes in skeletal muscle fibers by dietary protein restriction.

The effects of dietary protein restriction on skeletal muscle fibers were studied according to morphological and biochemical approaches. Protein and DNA content of quadriceps muscles from young adult rats were decreased by the low protein and protein-free diet. Morphological examination demonstrated that there was a significant decrease in the size of muscle fibers without change in their numbers due to protein restriction. The protein/DNA ratio, accepted as an index of cell size in biochemical approaches, was compared with cell size on photomicrographs. Actual fiber size appeared much smaller than that indicated by the protein/DNA ratio.

Animals↗

PubMed1995

Dietary protein and the renin-angiotensin system in chronic renal allograft rejection.

We examined the effects of dietary protein restriction in fourteen patients with chronic kidney rejection. The patients were randomly assigned, using a crossover design to two 11-day periods, one on a low-protein diet (0.55 g/kg/day) and the other on a high-protein diet (2 g/kg/day). The low protein diet was associated with a significant improvement in glomerular permselectivity without any change in blood pressure, glomerular filtration rate, or renal plasma flow. The low protein diet was also associated with a significant reduction in plasma renin activity. Acute converting enzyme inhibition decreased proteinuria when administered at the end of the high protein diet, but had no additional antiproteinuric effect when given at the end of the low protein diet. Comparable reductions in blood pressure with hydralazine had no effect on proteinuria. Protein restriction was also associated with modest but significant fall in serum proteins. In conclusion, dietary protein restriction may improve the course of renal failure in chronic rejection partly by suppressing the renin-angiotensin system. Studies are needed to establish the safe level of dietary protein restriction in these patients and to assess the efficacy of such restriction in slowing the progression of renal failure.

Cross-Over Studies↗

PubMed1991

Influence of dietary protein and recombinant porcine somatotropin administration in young pigs: II. Accretion rates of protein, collagen, and fat.

The present study was conducted to determine the effects of different dietary protein levels and recombinant porcine somatotropin (rpST) administration on deposition rates of protein, fat, water, ash, and collagen in pigs. Ten groups of six barrows (30 kg BW) were restrictively fed (80% of ad libitum) one of five diets containing 11, 15, 19, 23, or 27% CP. Diets were isoenergetic and all contained equivalent amounts of lysine. Thirty barrows were treated daily with rpST (100 micrograms/kg) by i.m. injection; remaining pigs were treated with diluent for 42 d. At all levels of dietary protein intake, carcass and empty body accretion rates of protein, water, and ash were greater in rpST-treated pigs than in respective controls. The magnitude of change elicited by rpST was lowest in pigs consuming 11% CP. Administration of rpST resulted in a 34% decrease in the accretion rate of fat; increasing protein intake resulted in a linear decrease in fat accretion in control and rpST-treated pigs. Accretion rates of protein, water, ash, and fat were increased in viscera of rpST-treated pigs compared with respective controls; rates of visceral protein and water accretion were increased as dietary protein was increased, whereas deposition of fat was decreased in control and rpST-treated pigs. Administration of rpST resulted in an overall 66% increase in the utilization efficiency of dietary protein for empty body protein deposition. Protein intake had minimal effect on the concentration of collagen in the carcass; however, rpST treatment increased concentrations of total and soluble collagen by 30 and 33%, respectively. Recombinant pST had little influence on collagen crosslinking or maturation. Deposition rate of carcass collagen was increased 63% in rpST-treated pigs compared with respective controls.

Adipose Tissue↗

PubMed1985

Alteration of the course of chronic renal failure by dietary protein restriction.

The role of dietary protein restriction in the progression of chronic renal failure has been investigated in 47 patients suffering with moderate and severe renal impairment. Prescription of a diet containing 0.6g/kg body weight protein resulted in 87 per cent of the patients exhibiting a diminution in the decline of renal function, as assessed by a reciprocal creatinine plot. Those patients with the most rapidly declining renal function showed the greatest response, but no correlation with initial renal function, age, sex or drug therapy could be found. No adverse nutritional effects, within the parameters examined, was found.

Adolescent↗

PubMed1983

Modifying factors in pancreatic carcinogenesis in the hamster model. IV. Effects of dietary protein.

The possible effects of dietary protein on pancreatic cancer induced in outbred Syrian golden hamsters by N-nitrosobis(2-oxopropyl)amine (BOP) were studied. Three levels of casein as protein at low [LP = 9 g/385 kilocalories (kcal)], medium (MP = 18 g/385 kcal), or high levels (HP = 36 g/385 kcal) were fed in two sequences to 4 groups of hamsters. The effects of protein level on the initiation phase of BOP carcinogenesis were examined in hamsters fed LP or HP from 3 through 7 weeks of age, followed by MP for the remainder of their lives. The role of protein level on the promotional (developmental) phase of carcinogenesis was evaluated in hamsters fed (from 3 through 7 wk of age) MP, followed by LP or HP for the rest of their lives. One-half of the hamsters from each of the 4 groups received a single sc BOP injection (10 mg/kg body wt) at 8 weeks of age. Changes in diet from one type to the other occurred 2 days after BOP treatment. An MP diet fed before and after BOP served as the experimental control diet. The results demonstrated that the LP diet inhibited the developmental phase of carcinogenesis only in females, whereas the MP and HP diets did not affect initiation or promotion of cancer in either sex. The inhibitory effect of the LP diet in pancreatic carcinogenicity only in females calls for further studies.

Animals↗

PubMed1990

The influence of dietary tryptophan on broiler chick growth and lipid metabolism as mediated by dietary protein levels.

Three experiments were conducted to determine how dietary protein and tryptophan influence the lipid metabolism of growing broiler chicks. A diet-dilution method (corn-corn gluten meal-gelatin summit/corn starch basal) was used in three factorial experiments. Various levels of protein and tryptophan were fed in each experiment: protein from 16 to 28% and tryptophan from .34 to 2.74% of protein. Gain was maximized when the dietary levels of tryptophan were .83 +/- .03, 77 +/- .04, 77 +/- .05, and .78 +/- .05% of the protein for 16, 20, 24, and 28% dietary protein, respectively. The requirement estimates for feed efficiency and gain were similar. Liver lipids significantly decreased as the level of dietary tryptophan increased at each protein level (P less than .0001). Dietary tryptophan did not significantly alter the concentration of total plasma lipid in the chicks or in the carcass lipid content (P greater than .2399). Tryptophan supplementation significantly increased the concentration of plasma linoleic acid and plasma free tryptophan. The requirement of the chicks for tryptophan was estimated to be .80 +/- .01% of the dietary protein for the growing chick. Increased liver lipid and decreased plasma tryptophan are diagnostic lesions suggesting a tryptophan deficiency.

Animal Feed↗

PubMed1999

Nutrition and chronic renal failure in rats: what is an optimal dietary protein?

In chronic uremia (CRF), malnutrition is an important determinant of morbidity in adults and impaired growth in children. Causes of malnutrition include anorexia and abnormal protein and amino acid metabolism. To determine how different levels of dietary protein and CRF interact to influence growth and nutritional status, CRF and sham-operated, pair-fed control rats were fed isocaloric diets containing 8, 17, or 30% protein for 21 d to mimic dietary regimens recommended for CRF patients: the minimum daily requirement; the recommended daily allowance; or an excess of dietary protein. Serum creatinine did not differ between groups of CRF rats but blood urea nitrogen was lowest in CRF rats fed 8% protein (P < 0.001). CRF rats eating 30% protein gained less weight and length compared to their controls or CRF rats fed 8 or 17% protein (P < 0.05); they also had acidemia. CRF rats fed 8% protein had the highest efficiency of utilization of protein for growth, while 17% protein promoted the highest efficiency of utilization of food and calories for growth. Notably, CRF rats eating 30% protein had the lowest protein efficiency; their calorie intake was also the lowest because of anorexia. Plasma branched-chain amino acids were progressively higher in control rats eating 8, 17, or 30% protein. CRF rats fed 8 or 17% protein had lower branched-chain amino acid concentrations compared with CRF rats fed 30% protein. In CRF, it is concluded that excessive dietary protein impairs growth but a low-protein diet does not impair nutritional responses and permits utilization of protein for growth if calories are sufficient.

Amino Acids, Branched-Chain↗

PubMed1990

Effects of dietary protein levels and cholesterol on tissue lipids of rats.

The effects of the levels (10, 20, and 30%) of dietary proteins, soybean protein or casein, on various lipid parameters were examined in rats. The plasma cholesterol (CHOL) level tended to decrease with an increasing dietary protein level, in particular when diets contained CHOL. The hypocholesterolemic effect of soybean protein was evident with CHOL-enriched diets. The fecal excretion of acidic but not neutral steroids increased with an increasing protein level and it was higher in rats fed soybean protein than in those fed casein. The ratio of arachidonate to linoleate in plasma and liver phosphatidylcholine tended to increase with an increasing dietary protein level, although it was considerably higher in casein than in soybean protein diets. The results indicated that the hypocholesterolemic effect of soybean protein is influenced not only by the amount but also by the presence or absence of dietary CHOL. In addition, the degree of conversion of linoleate to arachidonate also depended on the type and level of dietary protein.

Animals↗

PubMed1985

Effects of dietary protein concentration on trace minerals in rat tissues at different ages.

Copper, iron and zinc concentrations were measured in tissues of young (2 mo), mature (14 mo) and aged (26 mo) male Fischer rats fed either a normal protein (16% casein) or high protein (32% casein) diet for 30 d. Spleen copper concentrations decreased with maturity but were not affected by dietary protein level. Age, dietary protein and age X protein interaction affected spleen iron concentrations. Splenic iron was increased significantly only in mature and aged rats fed the normal protein diet. High protein-fed aged rats had decreased splenic zinc. High protein feeding increased renal zinc in the young and aged rats compared to normal protein feeding. At both protein levels, liver iron increased in the mature rats. Upon aging, zinc levels in the heart increased in the normal protein group and decreased in the high protein group. A significant interaction between age and protein was observed on heart zinc. Thus, the concentrations of tissue trace minerals are affected by age, dietary protein and protein X age interaction in young, mature and aged male rats.

Aging↗

PubMed1986

Influence of dietary protein concentration on the oxidation of phenylalanine by the young pig.

1. Piglets were weaned at 3 d of age and reared to 2.5 kg on a liquid diet in which the protein was supplied by dried skim milk and a mixture of free amino acids. The oxidation of L-[1-14C]phenylalanine was measured as an indication of the partition of amino acids between retention and catabolism in pigs (2.5 kg) offered meals containing varied concentrations of crude protein (nitrogen x 6.25). 2. The dietary protein concentration was varied either by increasing the inclusion of a mixture of free amino acids in a series of diets containing 100 g protein/kg from skim milk, or by increasing the level of inclusion of the skim milk in a series of diets containing the equivalent of 100 g protein/kg from the free amino acid mixture. 3. The oxidation of phenylalanine was minimized by dietary protein concentrations of 240 and 258 g/kg for the diets containing increasing concentrations of free amino acids or skim milk respectively. 4. These results show that a mixture of free amino acids is used more effectively than intact protein for promoting retention of essential amino acids. 5. The recovery of radioactivity in expired carbon dioxide was inversely related to the recovery of radioactivity in liver tissue when the concentration of dietary crude protein was increased from deficient to adequate, demonstrating that the fractional oxidation of the indicator amino acid was inversely related to protein synthesis.

Animals↗

PubMed2004

Optimum dietary protein requirement in nondiabetic maintenance hemodialysis patients.

BACKGROUND: There is controversy about whether the dietary protein requirement of 1.2 g/kg/d for hemodialysis (HD) patients, in the nutritional guidelines recommended by the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-KDOQI), is reasonable. METHODS: A cross-sectional study was conducted in 129 stable HD patients without diabetes (84 men, 45 women) to investigate the association between the protein equivalent of nitrogen appearance normalized by ideal body weight (nPNAibw), an index of protein intake, and skeletal muscle mass or other metabolic consequences. Patients were divided into 5 groups according to nPNAibw index. Midthigh muscle area (TMA), midthigh subcutaneous fat area (TSFA), abdominal muscle area (AMA), abdominal subcutaneous fat area (ASFA), and visceral fat area (AVFA) were measured using computed tomography, and various nutritional parameters were compared among these groups. RESULTS: TMA and AMA values increased with increasing dietary protein intake from less than 0.7 g/kg/d to 0.9-1.1 g/kg/d and showed a plateau at greater than 0.9 to 1.1 g/kg/d of dietary protein intake. Conversely, fat mass, including TSFA, ASFA, and AVFA, and serum potassium concentration increased with graded protein intake, and no plateau was formed. Patients with nPNAibw greater than 1.3 g/kg/d satisfied the criterion of visceral obesity. Although serum prealbumin levels showed a trend similar to that of muscle mass, there was no significant difference in serum albumin levels among the study groups. CONCLUSION: Optimal dietary protein requirement for patients undergoing maintenance HD in a stable condition appears to be less than the level recommended by the NKF-KDOQI nutritional guidelines.

Adipose Tissue↗

PubMed1982

Influence of dietary protein concentration and frequency of diet changes on rate of growth, efficiency of food utilisation and carcass quality of Large White turkeys.

1. In two experiments, diets in which the protein concentration was adjusted at differing intervals were fed to Large White turkeys for 22 or 24 weeks for males or 16 weeks for females. Four dietary protein concentration regimes were provided within each feeding plan. 2. The frequency of changes in dietary protein concentration had little influence on the rate of growth of turkeys receiving adequate dietary protein. However, lower dietary protein sufficed to maintain the maximum growth rate when the diets were changed less frequently. 3. The frequency of diet changes did not influence the efficiency of food or energy utilisation, but frequent dietary adjustments promoted efficiency of protein utilisation. 4. Higher dietary protein intake tended to increase carcass fleshing as assessed visually, without apparent effect on carcass finish. 5. Of two strains of turkeys studied, the more rapidly growing strain was less efficient in conversion of food and its constituent energy and protein into live body weight, but deposited carcass fat (finish) at an earlier age.

Animals↗

PubMed1998

Dietary protein and zinc restrictions independently modify a Heligmosomoides polygyrus (Nematoda) infection in mice.

The effects of dietary protein and zinc restrictions on Heligmosomoides polygyrus were compared following primary and challenge infection in female BALB/c mice fed either control (24%), marginal (7%) or low (3%) protein combined with either high or low zinc (60 or 3 mg Zn/kg diet). Dietary protein restriction (3%) resulted in significantly lower body weight gain. As well, blood urea nitrogen (BUN) significantly decreased with decreasing dietary protein level. However, neither plasma albumin concentration nor relative thymus or spleen weights were reduced. Marginal zinc deficiency was confirmed by significantly lower tibia and liver zinc concentration, but food intake, body weight gain, relative thymus and spleen weights, and alkaline phosphatase activity were not altered. On day 29 post-primary infection, worm burdens were significantly higher in mice fed either marginal or low protein and in mice fed a low zinc diet, while parasite egg output was significantly higher in mice fed both low protein and low zinc diet. Immune status was compromised in mice fed low protein (significantly lower serum IgG1 and lower eosinophilia), and in mice fed low zinc diet (significantly lower eosinophilia). Early in the infection, IgE titres were elevated in mice fed low protein or low zinc, but IgE titres declined to levels lower that the control diet groups after 14-21 days. On day 29 post-challenge infection, worm burdens and parasite egg output were significantly higher in mice fed low protein, whereas the other group had expelled almost all parasites. Dietary restriction had no effect on IgE. Significantly reduced serum IgG1 titres and eosinophilia in mice fed 3% protein supported the view that low dietary protein but not low zinc increased host susceptibility to H. polygyrus by compromising host immune function following reinfection in immunized mice.

Animals↗

PubMed1982

Effect of dietary protein and energy on broiler carcass composition and efficiency of nutrient utilization.

Day-old broilers were offered diets varying in dietary protein (16, 20, 24, 28, 32, 36%) and energy (2600, 2800, 3000, 3200, 3400, 3600 kcal [metabolizable energy] ME/kg) to 49 days of age to determine the effect of alteration in nutrient density on carcass composition and efficiency of nutrient utilization. Abdominal and total carcass fat contents responded similarly to alterations in dietary protein and energy, whether expressed on a percentage or absolute weight basis. However, maximum protein deposition occurred with the 20% crude protein diet, in contrast to the increase in percent carcass protein observed above this level. Although percent carcass protein decreased throughout the energy range tested, absolute carcass protein remained constant regardless of the dietary energy level. Dietary protein exerted similar effects on both absolute and percent carcass moisture. However, an increase in dietary energy resulted in a decrease in percent carcass moisture and an increase in absolute carcass moisture. Protein utilization decreased with each increment of dietary protein but increases in dietary energy resulted in small increases in protein utilization throughout the range tested. Changes in dietary protein and energy resulted in small differences in efficiency of energy utilization. Regression equations derived for carcass composition demonstrated that although diet composition is inadequate as a predictor of carcass parameters, the addition of carcass moisture (%) to the equation improves the reliability of the estimate. Equations for the prediction of nutrient utilization from diet composition are also presented.

Animals↗

PubMed1983

Antibody response against newcastle disease in commercial broilers fed different dietary protein levels.

A factorial experiment was conducted with two levels of dietary protein (17.5 and 26%) and three vaccination regimens (inactivated oil-emulsion, live LaSota strain, and unvaccinated) against Newcastle disease at 10 days of age. There were two trials with 3 pens of 15 male broiler chicks each per cell. Birds fed the high protein diet grew significantly better (P less than .05) in the second trial (1731 g at 6 weeks vs. 1622 g) but not in the first (1304 vs. 1244 g); no growth differences were noted due to vaccine. At 3 weeks of age, the hemagglutination-inhibition antibody titers from the live vaccine were significantly (P less than .01) higher than from the inactivated vaccine. At 3 weeks of age, antibody titers from the inactivated vaccine were elevated (P less than .05) in birds fed the low protein diet in the second trial. At 6 weeks of age, antibody titers were affected by vaccine (P less than .05) but not by dietary protein. Antibody titer levels were higher from the inactivated vaccine than from the live vaccine in the first trial; these results were reversed in the second trial. Postchallenge results with the Texas GB strain of Newcastle did not reveal any significant differences due to dietary protein content, trial, or type of vaccine.

Animals↗

PubMed1994

Additive effects of dietary protein and energy deficiencies on mandibular growth in the weanling rat.

Dietary protein restriction adversely affects mandibular growth in the weanling rat. Protein deficiency is usually accompanied by reduced food intake which, in turn, induces energy deficiency. The present study was thus designed to dissociate the effects of dietary protein and energy deficiencies on the growth of the mandible in rapidly growing rats. Four groups of Sprague-Dawley rats aged 30 days were fed a normal diet, a low-energy diet, a low protein diet, and a low-protein and low-energy diet for 20 days. Rats were sacrificed at the end of experimental period and body weight and mandibular dimensions were recorded to evaluate body growth and mandibular growth. The growth of the mandible was affected almost in the same order of magnitude by both protein and energy restrictions. When both were applied together, mandibular growth was even more severely affected. Two way analysis of variance revealed the absence of synergism between variables, indicating that the negative effects of dietary protein and energy restrictions on mandibular growth could be considered to be additive.

Analysis of Variance↗

PubMed1986

Factors affecting aminoglycoside disposition: effects of circadian rhythm and dietary protein intake on gentamicin pharmacokinetics.

The effects of dietary protein loading and circadian cycle on the pharmacokinetics of gentamicin were studied in healthy adult men. Ten subjects fasted overnight, and at 8 AM the next morning they received gentamicin, 1.5 mg/kg. Serum and urine samples were obtained over a 6-hour period. In two additional clearance studies with 2-week washout periods in between, 10 subjects were given the same dose of gentamicin at 8 PM in the fasted state and six subjects were also studied in a protein-supplemented (90 gm) state. Pharmacokinetic analysis revealed no significant effect of circadian cycle on gentamicin pharmacokinetic parameters at each of the two fasted periods. In contrast, dietary protein loading resulted in a significant decrease in the elimination t1/2 (P less than 0.05) and an increase in total body clearance compared with the fasted 8 PM study. Urinary excretion of gentamicin was also found to increase significantly (P = 0.03) as a result of protein intake compared with the fasted evening study period. Our study demonstrates the importance of dietary controls in chronopharmacokinetic studies of drugs eliminated predominantly by renal mechanisms.

Adult↗

PubMedDate not supplied

The effects of normalization of dietary protein intake and carotid artery ligation on the renal autoregulatory abnormalities of streptozotocin diabetic rats.

We studied renal autoregulation in nondiabetic and streptozotocin diabetic Münich-Wistar rats 6 weeks after diabetes induction. We had previously shown that diabetic rats had greater preservation of renal blood flow (RBF) at reduced renal perfusion pressures (RPP) than control rats and speculated that this could be due to higher protein intake in the diabetic rats. Because of hyperphagia, the diabetic rats in the present study on a 24% protein diet (D-24) had 70% or greater increase in dietary protein intake compared to controls on the same diet (C-24). Diabetic rats on a 14% protein diet (D-14) had a dietary protein intake similar to C-24 and less than that of D-24 animals. Baseline glomerular filtration rate (GFR) and renal blood flow were lower and renal vascular resistance (RVR) was higher in the D-14 compared to the C-24 or D-24 rats. Nonetheless, at markedly reduced RPP both diabetic groups had better sustained RBFs and lower RVRs than the controls. Thus, increased dietary protein intake cannot explain the autoregulatory abnormalities in diabetes. Bilateral carotid artery ligation increased systemic blood pressure similarly in the C-24, D-24, and D-14 rats. All three groups responded with increased RVR to carotid artery ligation. Following carotid artery ligation, differences were no longer seen between diabetic and control rats for RBF at reduced RPPs. These studies indicate that diabetic rats are capable of generating increased RVR, ruling out impaired vascular constrictive capacity as an explanation of these hemodynamic abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗