Showing papers on "Low protein published in 1987"
TL;DR: It is concluded that protein-calorie malnutrition early in life persistently impairs the insulin secretion, and the persistently lowered protein/DNA ratios in many tissues may be related to this lowered capacity for insulin secretion.
Abstract: The effect of a limited period of protein-calorie malnutrition in young rats on glucose tolerance, insulin secretory response to glucose, and tissue composition in the adult was studied. Three-week-old rats were weaned onto semisynthetic diets containing either 5% protein (low protein; LP) or 15% protein (control; C) and maintained for 3 wk on their respective diets. At 6 wk of age all rats were returned to a commercial rat chow diet (18% protein). Glucose tolerance, insulin secretory response to glucose, and the protein/DNA ratio in liver, skeletal muscle, heart, kidney, small intestine, and lung were investigated at 3, 6, and 12 wk of age. Rats receiving LP diet failed to gain weight, but growth resumed immediately when they were transferred to commercial rat chow. They did not, however, catch up with C rats. Glucose tolerance and insulin secretory response to glucose remained similar between 3 and 12 wk in C rats. In 6-wk-old LP rats, glucose tolerance was impaired, and the insulin secretory response to glucose was absent. At 12 wk of age the glucose tolerance of the LP rats had normalized, but the insulin secretory response was still blunted. In 6-wk-old LP rats there was an inhibition of the age-dependent increase in cell size, shown by lowered protein/DNA ratios in all tissues studied. This decrease in cell size persisted at 12 wk in liver, skeletal muscle, heart, and lung. We conclude that protein-calorie malnutrition early in life persistently impairs the insulin secretion. The persistently lowered protein/DNA ratios in many tissues may be related to this lowered capacity for insulin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)
145 citations
TL;DR: In this paper, the acid buffering capacity of 52 feeds was measured to determine the buffering range within and among feed types, and two isonitrogenous and isocaloric diets substantially different from each other were formulated using ingredients from the pool of 52 feed types.
139 citations
TL;DR: The results indicate that NC cell migration on FN involves two separate domains of the molecule, and that ChSP can modulate the migratory behavior ofNC cells moving along FN-rich pathways and may therefore influence directionally and subsequent localization of NC cells in the embryo.
Abstract: The ability of purified extracellular matrix components to promote the initial migration of amphibian neural crest (NC) cells was quantitatively investigated in vitro. NC cells migrated avidly on fibronectin (FN), displaying progressively more extensive dispersion at increasing amounts of material incorporated in the substrate. In contrast, dispersion on laminin substrates was optimal at low protein concentrations but strongly reduced at high concentrations. NC cells were unable to migrate on substrates containing a high molecular mass chondroitin sulfate proteoglycan (ChSP). When proteolytic peptides, representing isolated functional domains of the FN molecule, were tested as potential migration substrates, the cell binding region of the molecule (105 kD) was found to be as active as the intact FN. A 31-kD heparin-binding fragment also stimulated NC cell migration, whereas NC cells dispersed to a markedly lower extent on the isolated collagen-binding domain (40 kD), or the latter domain linked to the NH2-terminal part of the FN molecule. Migration on the intact FN was partially inhibited by antibodies directed against the 105- and 31-kD fragments, respectively; dispersion was further decreased when the antibodies were used in combination. Addition of the ChSP to the culture medium dramatically perturbed NC cell migration on substrates of FN, as well as of 105- or 31-kD fragments. However, preincubation of isolated cells or substrates with ChSP followed by washing did not affect NC cell movement. The use of substrates consisting of different relative amounts of ChSP and the 105-kD peptide revealed that ChSP counteracted the motility-promoting activity of the 105-kD FN fragment in a concentration-dependent manner also when bound to the substrate. Our results indicate that NC cell migration on FN involves two separate domains of the molecule, and that ChSP can modulate the migratory behavior of NC cells moving along FN-rich pathways and may therefore influence directionally and subsequent localization of NC cells in the embryo.
132 citations
TL;DR: A new, simple and rapid procedure for the purification of high amounts of mitochondrial porins from different tissues of mammalia is described, involving a single step hydroxyapatite/celite chromatography of Triton X-100 solubilized mitochondrial membranes.
94 citations
TL;DR: The structural and biochemical characterization of talin is described, a protein localized to various cellular sites where bundles of actin filaments attach to the plasma membrane which unfolds to become an elongated flexible molecule as the ionic strength is increased to physiological and higher levels.
93 citations
TL;DR: None of the 1381 subjects examined had diabetes, suggesting that a high carbohydrate/cassava intake combined with a low protein consumption does not cause diabetes, and does not support the World Health Organisation hypothesis that malnutrition-related diabetes exists, at least not in this West African rural population.
84 citations
TL;DR: Two hundred and forty Hubbard X Hubbard broiler breeders at 19 weeks of age were weight-sorted and transferred to individual laying cages where one of six experimental diets was provided to 41 weeks ofAge, with no dietary effects on hatchability, embryonic mortality, or fertility.
81 citations
TL;DR: The integral membrane protein complex of the photosystem I reaction center from the cyanobacterium Synechococcus sp. has been isolated and highly purified as discussed by the authors, and at extremely low protein complex concentrations (50 μg/ml), crystallization occurred.
78 citations
TL;DR: Brown adipose tissue protein content and thermogenic capacity were greater than control values in sucrose-fed and protein-deficient animals, and the greatest levels of activity were seen in low protein-fed rats with a high fat intake.
Abstract: Voluntary intake of protein, fat and carbohydrate (CHO) was modified by feeding young rats either a control purified diet [% metabolizable energy (ME): protein 21, fat 7, CHO 72], a control diet plus sucrose solution (20%) to drink (final intakes 17, 6 and 77% ME as protein, fat and CHO, respectively) or a low protein diet substituted with either CHO (8, 7 and 85% ME as protein, fat and CHO, respectively) or fat (8, 20 and 72% ME as protein, fat and CHO, respectively). Total ME intakes corrected for body size were similar for all rats, but body weight, energy gain and net energetic efficiency were lower in both low protein-fed groups than in the control group. The acute thermogenic response (% rise in oxygen consumption) to a standard balanced-nutrient meal was higher (12%) in sucrose-supplemented and in low protein groups (15-16%) than in control rats (8%). Brown adipose tissue protein content and thermogenic capacity (assessed from purine nucleotide binding to isolated mitochondria) were greater than control values in sucrose-fed and protein-deficient animals, and the greatest levels of activity were seen in low protein-fed rats with a high fat intake. The results demonstrate that the changes in energy balance, thermogenesis and brown adipose tissue activity that result from protein deficiency cannot be ascribed to changes in the level of energy intake or to a specific increase in the amount or proportion of either CHO or fat. They suggest that the protein-to-energy ratio must be the primary influence on thermogenesis and brown fat activity in these animals.
75 citations
TL;DR: The pharmacokinetics of ceftriaxone in an animal species with binding characteristics similar to man (baboon), appear to be non-linear when based on total drug concentration and linear whenbased on the free drug concentration.
Abstract: 1. The plasma protein binding characteristics of ceftriaxone, a new cephalosporin antibiotic, were determined in human, baboon, rabbit, dog and rat plasma. 2. The protein binding of ceftriaxone was similar and concentration-dependent in human, baboon, rabbit and rat plasma, being highly bound (90-95%) at low concentrations (less than 100 micrograms/ml) but considerably less bound (approx. 60%) at high concentrations (greater than 400 micrograms/ml). Binding in dog plasma was also concentration-dependent but much lower (approx. 25%) at lower concentrations (30 micrograms/ml) and virtually unbound (2%) at high concentrations (1 mg/ml) over a similar concentration range. 3. Binding of ceftriaxone to human plasma involved two sites: a high affinity-low capacity (saturable) site and a low affinity-high capacity site. Binding to dog plasma apparently was at a single, high affinity-low capacity site. 4. The pharmacokinetics of ceftriaxone in an animal species with binding characteristics similar to man (baboon), appear to be non-linear when based on total drug concentration and linear when based on the free drug concentration. In the dog, pharmacokinetic parameters did not change appreciably if calculated from total or free drug concentrations, due to the low protein binding.
69 citations
TL;DR: The observations reemphasize the importance of diet in drug disposition and suggest that the clearance of high‐clearance drugs like propranolol is more susceptible to dietary manipulations, effects that may have to be considered in drug therapy.
Abstract: The objective of this study was to determine whether changes in dietary protein and carbohydrate influence the oral clearance of propranolol, a high-clearance drug, and theophylline, a low-clearance drug. Six normal subjects studied in a clinical research center each received a single oral dose of propranolol, 80 mg, and theophylline, 5 mg/kg, after having been on each of two well-defined diets for a period of 10 days. When the diet was altered from high carbohydrate/low protein to low carbohydrate/high protein, the oral clearance of propranolol increased by 74% +/- 20% (mean +/- SE; range 9% to 156%; P less than 0.01) with no change in plasma half-life or plasma binding. This dietary change resulted in an increase in theophylline clearance of 32% +/- 6% (range 18% to 50%; P less than 0.02) and a corresponding decrease in plasma half-life of 26% +/- 6% (range 6% to 42%; P less than 0.05) with no alteration in the apparent volume of distribution. These observations reemphasize the importance of diet in drug disposition and suggest that the clearance of high-clearance drugs like propranolol is more susceptible than the clearance of low-clearance drugs to dietary manipulations, effects that may have to be considered in drug therapy.
TL;DR: Results of both the experiments have demonstrated that diets containing 32-37% crude protein with digestible energy (DE) above 340kcal/100g diet enriched with carbohydrate or lipid were found to be better than a commercial cazp diet above 40% in growth and feed efficiency.
Abstract: Two feeding experiments were conducted for both practical and experimental scales to develop low-protein high-energy diets (less-polluting diets) for practical carp culture in order to reduce the total nitrogen excretion from the fish. Results of both the experiments have demonstrated that diets containing 32-37% crude protein (CP) with digestible energy (DE) above 340kcal/100g diet enriched with carbohydrate or lipid were found to be better than a commercial cazp diet containing CP above 40% in growth and feed efficiency. This fact indicated that CP content in practical carp feeds can be reduced from 40% to around 30% without reduction of growth rate and feed efficiency, if a high quality protein is used as protein source and DE content is increased by carbohydrate or lipid to about 340kcal/100g diet. The total nitrogen excretion from carp was also found to be reduced by 30-48% of the present value by feeding these low protein-high energy diets.
TL;DR: It is suggested that somatomedins are required for elevation of serum 1,25-(OH)2D3 levels in response to phosphate deprivation.
Abstract: The present studies were undertaken in an effort to determine whether somatomedins (SMs) play a role in the elevation of serum 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] levels during dietary phosphate deprivation. Serum 1,25- (OH)2D3, SM-C, and phosphate levels were measured in rats fed diets containing adequate or very low levels of dietary phosphorus under circumstances known to affect SM levels, including hypophysectomy with and without GH replacement, normal protein vs. low protein diets, and streptozotocin-induced diabetes with and without insulin replacement. In all circumstances, serum 1,25-(OH)2D3 concentrations were directly related to serum SM-C levels. However, the slope for the relationship was increased 2- to 10-fold in animals fed the low phosphorus diets. As observed previously, serum 1,25-(OH)2D3 levels were inversely related to serum phosphate levels, but the slope for this relationship was decreased in the presence of low SM levels and absent in animals with very low SM levels. These resul...
TL;DR: Data are interpreted to suggest that blood urea-N may provide a substantial quantity of N for bacterial protein synthesis and, thus, may be an important source of protein in the deficient animal.
Abstract: Six wether lambs (31 kg) were randomly assigned to two treatments (three lambs/treatment): a high protein intake (HP; 21 g N/d) or a low protein intake (LP; 12 g N/d). Each lamb received 860 g/d dry matter (DM) of a pelleted diet (75% corn-soybean meal, 25% cottonseed hulls) offered hourly in 24 equal portions. Single injections of 15N-labelled compounds were made into the ruminal NH3-N and blood urea-N pools to measure the rate of flux through, and transfer of N between, these and the bacterial N pool. Total tract digestibilities of DM and N were lower (P less than .05) for the LP than the HP treatment. Abomasal flows of total, feed or bacterial N tended to be greater (P greater than .05) in lambs fed HP than LP. Lambs fed HP excreted more (P less than .01) urinary N, yet retained a greater (P less than .01) amount of N than lambs fed LP (6.2 vs 1.8 and 9.7 vs 4.1 g N/d, respectively). Pool size and production rate for both ruminal NH3-N and blood urea-N were greater (P less than .05) for the HP than LP treatment. Lambs consuming HP degraded more (P less than .05) blood urea-N in the gastro-intestinal tract (13.4 vs 6.9 g N/d); however, lambs fed LP degraded a greater (P less than .05) percentage of synthesized body urea-N (88.7 vs 71.8%). Ruminal NH3-N absorption was greater (P less than .01) for the HP than LP treatment (3.1 vs .5 g N/d). Although the percentage of bacterial N derived from ruminal NH3-N was similar (P greater than .05) between diets (51.1 vs 63.9), a greater (P less than .05) percentage of bacterial N was derived from blood urea-N in lambs fed LP than HP (77.1 vs 30.2%). Lambs fed LP incorporated a greater (P less than .10) amount of blood urea-N into bacterial N than lambs fed HP (5.5 vs 2.6 g N/d). These data are interpreted to suggest that blood urea-N may provide a substantial quantity of N for bacterial protein synthesis and, thus, may be an important source of protein in the deficient animal. In addition, urea recycling may play an important role in the recovery of ruminal NH3-N lost through absorption in animals fed a high level of protein.
TL;DR: In this article, a novel processing scheme was developed which included extraction with an aqueous sodium hexametaphosphate or sodium hydroxide solution, ultrafiltration, isoelectric precipitation at pH 35, and diafiltration.
Abstract: Previously reported rapeseed protein isolation methods resulted in low yields or low protein purity The isolates often had an unpleasant taste or dark colour, and the levels of glucosinolates, phytates or both in these products were a source of concern A novel processing scheme was developed which included extraction with an aqueous sodium hexametaphosphate or sodium hydroxide solution, ultrafiltration, isoelectric precipitation at pH 35, and diafiltration An isoelectric protein fraction and a soluble protein fraction were produced Up to 712% of the nitrogen was recovered in the isolates The protein content of the isoelectric protein and soluble protein isolate was close to or higher than 90% (N × 625) A phy-tate content of less than 2% was achieved These isolates were free of glucosinolates
TL;DR: Growth was decreased in birds fed the low protein diet due to restriction of protein, sustained low feed intake and hence possibly insufficient energy for growth.
Abstract: The hormonal response to protein restriction was studied in breeds of chickens with different rates of growth and body size. Fast-growing (broiler) chicks and lighter-weight (White Leghorn) birds were fed isoenergetic 5% (low) and 20% (control) protein diets ad libitum starting at 2 wk of age. At 4 wk of age, one-half of each group continued receiving the initial diet, while the other half was fed the alternate diet for two additional weeks. Growth was decreased in birds fed the low protein diet due to restriction of protein, sustained low feed intake and hence possibly insufficient energy for growth. Birds fed low protein diets had higher plasma growth hormone (GH) concentrations (325% in Leghorns and 233% in broilers) compared with controls. Plasma concentrations of somatomedin-C in protein-restricted Leghorn and broiler chicks were only 50 and 34% of those of controls, respectively. Similarly plasma concentrations of thyroxine (T4) and triiodothyronine (T3) were reduced in protein-deprived birds compared with those fed adequate protein. Plasma T3 concentrations of restricted birds were 48 (Leghorns) and 47% (broilers) of those of controls, whereas plasma T4 concentrations were 44 (Leghorns) and 41% (broilers) of those of controls.
TL;DR: The brain edema fluid spread, as revealed by specific gravity measurements, corresponded to the intracerebral distribution of extravasated plasma proteins.
Abstract: Brain edema associated with severe chronic hypertension was studied in stroke-prone spontaneously hypertensive rats (SHRSP), 5 to 9 months of age. Blood-brain barrier (BBB) leakage sites and intracerebral spreading pathways for plasma proteins were delineated by an intravenously (i.v.) injected exogenous dye tracer (Evans blue), known to form a complex with albumin in blood, and by immunohistochemical visualization of extravasated endogenous plasma proteins. The tissue content of edema fluid was estimated by measuring the specific gravity of selected brain regions, stained or unstained by the tracer dye, on a bromobenzene-kerosene gradient column. Multifocal BBB leakage sites were macroscopically detected within the cerebral cortex and the deep gray matter after i.v. circulation of Evans blue-albumin for 30 min. After 24 h of i.v. circulation the dye tracer had spread not only locally in the gray matter but also into the adjacent white matter, where it was widely distributed. Immunohistochemically visualized plasma proteins showed similar distribution. Unilateral superior cervical ganglionectomy performed at 4 weeks of age neither increased the incidence of major BBB opening to Evans blue-albumin nor altered the specific gravity of the ipsilateral cerebral hemisphere in grown-up SHRSP, furthermore, the blood pressure remained unchanged. The lack of significant effect on BBB function may possibly be attributed to the extensive reinnervation of the cerebral arteries, verified in the grown-up SHRSP using the Falck-Hillarp fluorescence method for visualization of catecholaminergic nerve fibers. In SHRSP raised on a low-protein and high-salt diet the mean arterial blood pressure was 212 mm Hg compared to 195 mm Hg in controls (P less than 0.05) and the incidence of BBB opening was 72% compared to 25% in controls (P less than 0.05). After 24 h of i.v. circulation of Evans blue-albumin, brain regions stained by the dye tracer showed significantly reduced specific gravity (P less than 0.001), while unstained regions had normal values. Thus the brain edema fluid spread, as revealed by specific gravity measurements, corresponded to the intracerebral distribution of extravasated plasma proteins.
TL;DR: Evidence is provided that intrarenal angiotensin II mediates the changes in intraRenal hemodynamics induced by protein deprivation, which suggests that if PGE2 is involved in these changes, it plays a permissive but not essential role in the increased renovascular resistance.
Abstract: We assessed the role of angiotensin II in mediating the alterations in renal hemodynamics known to result from low protein feeding to normal rats by examining the effect of the angiotensin-converting enzyme (ACE) inhibitor captopril. 2 wk of low protein (6% casein) diet resulted in decreased glomerular filtration rate (normal protein [NP], 1.82 +/- 0.17 vs. low protein [LP], 0.76 +/- 0.01 ml/min; P less than 0.05) and renal plasma flow (NP, 6.7 +/- 0.2 vs. LP, 3.3 +/- 0.3 ml/min; P less than 0.05); renal vascular resistance rose (NP, 8.7 +/- 0.4 vs. LP, 19.8 +/- 1.4 dyn . s per cm5; P less than 0.05). These changes were accompanied by a significant decrease in plasma renin activity (NP, 7.0 +/- 0.7 vs. LP, 4.4 +/- 0.8 ng A I/ml per h; P less than 0.05), plasma aldosterone concentration (NP, 7.0 +/- 0.6 vs. LP, 4.1 +/- 0.7 ng/dl; P less than 0.05), and urinary PGE2 excretion (NP, 3,120 +/- 511 vs. LP, 648 +/- 95 pg/mgCr; P less than 0.05); by contrast renal renin content was significantly increased (NP, 2,587 +/- 273 vs. LP, 7,032 +/- 654 ng A I/mg protein; P less than 0.05). Treatment with captopril (30 mg/kg per d) raised glomerular filtration rate (GFR; LP + capt, 1.6 +/- 0.2 ml/min) and renal plasma flow (RPF; LP + capt, 6.7 +/- 0.7 ml/min), and reduced renal vascular resistance (LP + capt, 9.2 +/- 0.5 dyn/s per cm5) in low protein-fed animals. These values were not different from those measured in untreated and captopril-treated rats fed a normal (23%) protein diet. There were no changes in systemic mean arterial pressure in any group of rats. These data provide evidence that intrarenal angiotensin II mediates the changes in intrarenal hemodynamics induced by protein deprivation. The effects of low protein feeding may be partly potentiated by the reduction in PGE2 synthesis. However, the normalization of GFR and RPF in view of only modest increases in PGE2 excretion after captopril (LP, 648 +/- 95 vs. LP + capt, 1,131 +/- 82 pg/mgCr; P less than 0.05) suggests that if PGE2 is involved in these changes, it plays a permissive but not essential role in the increased renovascular resistance.
TL;DR: The results show thatXL-AP is superior to AP for use in conjugates that absorb and emit in the red region of the spectrum and the high stability of XL-AP at elevated temperatures at high phosphate concentrations suggests that this derivative may be useful in conjunction with nucleic acid probes.
Abstract: Data on the wavelength and temperature dependence of both time-resolved and steady state fluorescence emission are presented for allophycocyanin (AP) and for a crosslinked allophycocyanin trimer (XL-AP) (Ong LJ and Glazer AN: Physiol Veg 23:777-787, 1985). AP dissociates at high dilution and is not stable above 40 degrees C even at moderate protein concentration. In contrast, XL-AP does not dissociate even at very low protein concentrations and is completely stable up to 60 degrees C in the presence of 0.75 M NaK-phosphate, pH 7.0. The results show that XL-AP is superior to AP for use in conjugates that absorb and emit in the red region of the spectrum. The high stability of XL-AP at elevated temperatures at high phosphate concentrations suggests that this derivative may be useful in conjunction with nucleic acid probes.
TL;DR: After the change to the high protein diet the foals that had been fed the low protein diet maintained a higher rate of gain in bodyweight, height and cannon circumference, and utilised feed more efficiently than the other two groups throughout the second 140 days of the experiment.
Abstract: Summary
The effect of level of protein intake on growth and calcium metabolism was studied in 24 foals. Starting at four months old, the foals were fed one of three diets containing all nutrients, with the exception of protein, at levels recommended by the United States National Research Council Subcommittee on Horse Nutrition for a 12 month period. The protein levels in the three diets were 9 per cent (low protein) 14 per cent (NRC recommended level) and 20 per cent (high protein). The foals fed the low protein diet were changed to the high protein diet after 140 days when they were nine months old. There were no significant differences in the rates of growth in weight, height, cannon circumference or in hoof growth and feed utilisation of the horses fed the 14 or the 20 per cent protein diets. However, growth, feed intake and feed utilisation by the foals fed the low (9 per cent) protein diet were significantly depressed. The average daily gains for the first 140 days for the 9, 14 and 20 per cent protein treatment groups were 64, 631 and 687 g in weight, 0.57, 0.83 and 0.87 mm in height and 0.04, 0.13 and 0.14 m in forecannon circumference, respectively. The average daily feed intakes for the 140 day period for the three groups were 2.7, 4.4 and 4.7 kg, respectively. After the change to the high protein diet the foals that had been fed the low protein diet maintained a higher rate of gain in bodyweight, height and cannon circumference, and utilised feed more efficiently than the other two groups throughout the second 140 days of the experiment. At the end of the second 140 days there were no longer differences in weight, height or cannon circumference among the treatment groups. Calcium and phosphorus balance studies were carried out using three foals from each treatment group when they were six months old and repeated with the same horses when they were 12 months old. Urinary calcium excretion averaged 23 to 30 per cent of calcium intake and calcium absorption averaged 52 to 77 per cent of intake. Neither was affected by the protein content of the diet. Bone turnover, as measured with 47Ca, was depressed in the foals fed the low protein diet. A concentration of dietary protein of 20 per cent which is significantly greater than the NRC recommended level of 14 per cent is neither helpful nor harmful to growing horses.
TL;DR: Growing rates were highest in males fed the high protein (HP) diet ad libitum and lowest in females consuming the low protein (LP) diet at restricted intakes, although the improved growth could be largely attributed to increased intake rather than to enhanced feed efficiency.
Abstract: Some aspects of growth and digestion were studied in Australian cashmere goats in two experiments. In the first experiment, weaner goats (initial LW 13.4 kg) were given three ground and pelleted diets (11.3, 16.0, and 20.9% crude protein) at two levels of intake. Growth rates were highest in males fed the high protein (HP) diet ad libitum (149 g day-1) and lowest in females consuming the low protein (LP) diet at restricted intakes (30 g day-1). Increasing the protein content of the diet resulted in significantly greater liveweight gains, although the improved growth could be largely attributed to increased intake rather than to enhanced feed efficiency. Males grew faster, retained more nitrogen and used feed with greater efficiency than did females. A second experiment with fistulated goats (mean liveweight 16.4 kg) fed the LP and HP diets from experiment 1 showed that organic matter (OM) digestion was greater in goats fed the LP diet (67.9% v. 65.3%). In contrast, the proportion of OM digestion which occurred in the stomach was greater for goats fed the HP diet (76.7 v. 57.4%). For both diets all of the cellulose and hemicellulose digestion took place in the rumen; however, substantial amounts of starch escaped rumen digestion. Large losses of nitrogen across the rumen (4.9 g day-1) in goats given the Hp diet resulted in reduced flows (11.1 g day-1) of non-ammonia nitrogen (NAN) to the small intestine, compared with the LP diet (12.7 g day-1). Digestion of NAN in the intestines was greater in animals consuming the LP diet, possibly reflecting the greater intestinal contribution made by non-microbial NAN. For both diets the ratio of protein to energy available (11.0 and 10.2 g protein MJ-1 ME for LP and HP diets respectively) was estimated to be in excess of maximum tissue requirements for growth.
TL;DR: The findings suggest that the altered balance between at least two factors of protein and energy intake serves as a trigger for several metabolic changes which ultimately regulate specific genes.
Abstract: The effects of diet at the molecular level were investigated by feeding rats control or protein-deficient diets. Each of the control and the protein-deficient groups was further divided into three subgroups according to the level of energy intake. Liver DNA, RNA and total cellular protein concentrations and serum albumin and albumin mRNA concentrations were determined. Protein deficiency caused a marked inhibition of liver growth but the size of most cells remained normal. The low protein diet caused concurrent decreases in the levels of serum albumin and serum mRNA. However, this effect was observed only with the combination of a low protein diet and normal energy intake. The low protein-low energy diet failed to induce the low serum albumin level. Our findings suggest that the altered balance between at least two factors of protein and energy intake serves as a trigger for several metabolic changes which ultimately regulate specific genes.
TL;DR: Excesses of dietary protein enhance the capacity of skeletal muscle to oxidize BCAA, muscle conserves BCAA when protein intake is inadequate, and skeletal muscle may play an important role in whole-body BCAA homeostasis.
Abstract: The effects of dietary protein on the activity of skeletal muscle branched-chain alpha-keto acid dehydrogenase (BCKAD) were investigated. BCKAD is rate-limiting for branched-chain amino acid (BCAA) catabolism by muscle; its activity is modulated by phosphorylation-dephosphorylation. In rats fed an adequate protein (25% casein) diet, BCKAD was approximately 2% active postabsorptively and increased to 10% or 16% active after a 25% or 50% protein meal, respectively. Prolonged feeding of a 50% protein diet increased postabsorptive BCKAD activity to 7% with further increases to 40% active postprandially. On a low protein (9% casein) diet BCKAD remained approximately 2% active regardless of meal-feeding. Dose-dependent activation of BCKAD by intravenous leucine in postabsorptive rats was blunted by a low protein diet. We conclude that excesses of dietary protein enhance the capacity of skeletal muscle to oxidize BCAA, muscle conserves BCAA when protein intake is inadequate, and skeletal muscle may play an important role in whole-body BCAA homeostasis.
TL;DR: Ten patients with advanced renal failure treated with a low phosphorus and low protein diet supplemented with ketoacid analogues and a three step euglycemic insulin clamp found that glucose tolerance had improved, and the tissue sensitivity index to insulin was significantly improved.
Abstract: Ten patients with advanced renal failure (glomerular filtration rate 25 mL/min) were treated with a low phosphorus and low protein diet supplemented with ketoacid analogues. Before starting the diet and four months afterwards, a 50 g oral glucose tolerance test with a three step euglycemic insulin clamp was carried out. A dose-response curve of total body insulin sensitivity was plotted. By the fourth month, glucose tolerance had improved with significantly lower T0, T30, and T60 insulin levels. These results are attributed to the improvement in insulin action as demonstrated by the clamp technique. The dose-response curve had a distinctly higher plateau after dietary treatment, and the tissue sensitivity index to insulin ( M I ratio) was significantly improved. It is suggested that treatment of uremic patients with a low protein diet may reduce levels of a putative insulin inhibitor.
TL;DR: The dye-binding method is unsuitable for protein assay in phenol- and phenolase-rich plant tissues because it gives grossly erroneous results when the homogenizing media differed.
TL;DR: Differences in plasma concentrations of free 3,5,3'-triiodothyronine (T3), non-esterified fatty acids and urea-nitrogen were not significant and fasting metabolic rate was significantly lower in implanted steers.
Abstract: 1. Six steers implanted with 300 mg trenbolone acetate and six steers not implanted were fed on low protein, low-quality-roughage diets ad lib. in two experiments. The steers were Hereford (Bos taurus) x Brahman (Bos indicus) crossbreds (50:50), initially of about 400 kg mean live weight (LW). In the first experiment of 8 weeks duration roughage was given alone. In the second experiment of 6 weeks duration the diet was supplemented with 100 g urea and 4.6 g sulphur daily. The same steers were implanted in each experiment. At the conclusion of each experiment metabolic rate was measured after a 72 h fast. 2. In the first experiment control and implanted steers had similar rates of LW loss (0.57 and 0.59 kg/d respectively). Implanted steers had significantly (P less than 0.01) lower feed intakes (12.8 v. 10.9 g dry matter (DM)/kg LW), significantly (P less than 0.01) lower fasting metabolic rates even after adjustment for intake (83.3 v. 74.5 kJ/kg per d) and significantly (P less than 0.01) lower plasma insulin concentrations (24 v. 19 mu units/ml). Differences in plasma concentrations of free 3,5,3'-triiodothyronine (T3), non-esterified fatty acids and urea-nitrogen were not significant. 3. In the second experiment intake of the supplemented diet was similar in both control and trenbolone acetate-treated steers (19.5 and 20.0 g DM/kg LW respectively). LW gains were 0.23 and 0.41 kg/d for control and implanted steers respectively, the difference being significant (P less than 0.05). Fasting metabolic rate (76.9 v. 70.7 kJ/kg per d) was significantly (P less than 0.05) lower in implanted steers.
TL;DR: Both amitriptyline- and desipramine-treated rats showed a potentiation of acute caloric intake after a single systemic injection of the glucoprivic agent 2-deoxy-D-glucose, considered against the background of human clinical observations.
Abstract: Long-term treatment with tricyclic antidepressant drugs (TCAs) can induce excessive body weight gain in a significant proportion of patients. Such weight gains, which appear to be largely independent of clinical improvement, are in many cases severe enough to interfere with continuation of treatment. In efforts to model this effect in experimental animals, seven experiments were performed in which two commonly used TCAs, amitriptyline and desipramine, were administered chronically to rats. Despite manipulations of drug dosages (2.5 mg−17 mg/kg), route of administration (intraperitoneal, subcutaneous, oral; daily injections vs. continuous release from osmotic pumps), diet composition and palatability (regular Purina Chow pellets or powder with or without added high fat and high carbohydrate sources; high vs. low protein diets) and animal sex and housing conditions (single vs. group housing), chronic TCA treatment was never observed to increase daily food intake or rates of body weight gain. Desipramine treatment invariably caused decreased food intake and weight loss. Amitriptyline treatment either caused no change in food intake and body weight or slightly reduced levels in comparison to vehicle-treated controls. However, both amitriptyline- and desipramine-treated rats showed a potentiation of acute caloric intake after a single systemic injection of the glucoprivic agent 2-deoxy-D-glucose. These results are considered against the background of human clinical observations. Possible reasons for the differences between human and animal data are discussed.
TL;DR: Serum urea N responded quadratically (P less than .05) to increasing dietary tryptophan, and was lower in pigs that were fed diets supplemented with L-tryptophan than in those fed the low protein basal or 18% protein diets.
Abstract: Four 28-d trials were conducted using a total of 432 pigs, with average initial weight across trials ranging from 6.3 to 9.7 kg, to estimate the tryptophan (trials 1 and 2) and threonine (trials 3 and 4) requirements of pigs fed low protein, corn-sunflower meal diets. The effect of tryptophan, threonine and protein level on serum calcium, phosphorus and zinc also was studied. The diets contained either 12 or 13% protein and were calculated to be adequate in all nutrients except crude protein and the amino acid being investigated. A lysine supplemented, 18% protein, corn-sunflower meal diet was included in all trials as a positive control. In trial 1, weight gains of pigs increased linearly (P less than .005) while feed conversion improved cubically (P less than .05) as dietary tryptophan increased from .14 to .22%. Pigs fed the 18% protein diet gained faster (P less than .05) and required less feed/gain than pigs fed low protein diets. In trial 2, weight gains improved quadratically (P less than .005) and feed conversion improved linearly (P less than .05) as dietary tryptophan increased from .104 to .204%. Serum phosphorus and zinc concentrations were lower (P less than .05) in pigs fed the 18% protein diet. In both trials, serum urea N responded quadratically (P less than .05) to increasing dietary tryptophan, and was lower (P less than .05) in pigs that were fed diets supplemented with L-tryptophan than in those fed the low protein basal or 18% protein diets.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: The blood in neonates shows several peculiar properties which affect its rheological properties, which results in decreased blood viscosity at given haematocrit, particularly at low shear forces.
Abstract: The blood in neonates shows several peculiar properties which affect its rheological properties. 1. The haematocrit in neonates may be as high as 0.65 l/l without any clinical signs. 2. Both plasma viscosity and red cell aggregation are markedly lower in neonates than in adults because of low protein levels in neonates. This results in decreased blood viscosity at given haematocrit, particularly at low shear forces. 3. Deformability of neonatal red cells is similar to that of adult cells when studied under controlled conditions (e.g. rheoscope, ektacytometer). However, neonatal red cells are less filterable and require higher pressures for entering narrow micropipettes than adult red cells due to the larger size of neonatal red cells. 4. Neonatal leukocytes require higher pressure for the passage of 5 microns filter pores or 5 microns micropipettes than adult cells. The following haemorheological disorders have been observed in neonates: 1. Polycythaemia in infants with late cord-clamping, severe asphyxia, growth retardation and diabetic mothers. 2. Markedly decreased red cell deformability in septicaemia, necrotizing enterocolitis and in vitamin E deficiency (after exposure to oxidizing agents). 3. Moderately decreased red cell deformability in infants with diabetic mothers, growth retardation and severe acidosis. 4. Increased red cell aggregation in septicaemia. 5. Lack of red cell aggregation in immature neonates. 6. Decreased ability of leukocytes from septic neonates to pass filter pores and micropipettes. Treatment may be either haemodilution (in polycythaemia) or exchange transfusion (in septicaemia and necrotizing enterocolitis). Haemorheological drugs have not been used in neonates.
TL;DR: The high-density lipoproteins apo A-I, A-II and A-IV, which are more than 50% synthetized in the intestine, remained essentially unchanged, thus showing resistance to protein malnutrition and only the levels of total apo C and apo B48 were correlated with hepatic TG steatosis during malnutrition and refeeding.
Abstract: The effects of protein malnutrition (PM) followed by refeeding a balanced diet on apolipoprotein and lipid contents of the serum lipoproteins were studied in young Wistar male rats. The changes of serum apolipoproteins were compared with the appearance of fatty liver during PM and its disappearance during refeeding. The control group (T) was fed a balanced diet containing 15% casein for 42 d. Two depleted groups (C) and (G1) were fed for 28 d low protein diets containing 2% casein and 5% gluten, respectively, and then were fed the balanced diet for 14 d. During PM a concentration of triacylglycerols (TGs) in liver in the two depleted groups increased; the level in rats fed 2% casein was twice that in rats fed 5% gluten. There was a significant negative correlation between serum TGs and liver TGs. The serum apolipoproteins (apo) did not respond consistently. The high-density lipoproteins apo A-I, A-II and A-IV, which are more than 50% synthetized in the intestine, remained essentially unchanged, thus showing resistance to protein malnutrition. The very low density lipoproteins apo B and total apo C, which mainly originate from liver, were significantly lower in malnourished groups than in controls, while the liver TGs accumulated in malnourished groups. Only the levels of total apo C and apo B48 were correlated with hepatic TG steatosis during malnutrition and refeeding.