Showing papers on "Low protein published in 1980"
TL;DR: The apparent digestibility coefficients for 4 size classes of the green turtle Chelonia mydas feeding on the seagrass Thalassia testudinum were measured in Union Creek, Great Inagua, Bahamas, from September 1975 to August 1976.
Abstract: The apparent digestibility coefficients for 4 size classes of the green turtle Chelonia mydas feeding on the seagrass Thalassia testudinum were measured in Union Creek, Great Inagua, Bahamas, from September 1975 to August 1976. The values ranged from 32.6 to 73.9% for organic matter; from 21.5 to 70.7% for energy; from 71.5 to 93.7% for cellulose; from 40.3 to 90.8% for hemicellulose; and from 14.4 to 56.6% for protein. Digestive efficiency increased with increases in water temperature and body size. There was no seasonal variation in the nutrient composition of T. testudinum blades. Grazing on T. testudinum may be limited by its low quality as a forage, a result of its high fiber content and possible low protein availability. Turtles did not graze at random over the extensive beds of T. testudinum, but maintained “grazing plots” of young leaves by consistent recropping. They thus consumed a more digestible forage-higher in protein and lower in lignin-than the ungrazed, older leaves of T. testudinum. The selectivity of green turtles for either a seagrass or algal diet may reflect the specificity of their intestinal microflora.
377 citations
TL;DR: The red yeast Phaffia rhodozyma has possible application as a component of diets for use in aquaculture because of its primary value in its content of astaxanthin, which is much higher than that found in crustacean meals.
179 citations
TL;DR: It is suggested that albumin synthesis in the elderly is controlled at a lower set point, which prevents its response to higher protein intakes, as well as whole body protein synthesis from urinary 15N-urea enrichment using the Picou and Taylor-Roberts model.
Abstract: Albumin synthesis was evaluated in 5 young adult males (19–25 yr) and 6 elderly males (64–78 yr) by a procedure involving oral administration of 15 N-glycine every 3 hr over a 60-hr period From about 40 hr onwards, urinary urea achieved a plateau of 15 N-enrichment, which was estimated from the average of the last five (low protein) or seven (adequate protein) consecutive three-hourly urinary samples of the 60-hr period This enrichment plateau was used as an index of the 15 N-enrichment of the guanidine N of hepatic free arginine The 15 N-enrichment of the guanidine N of arginine in serum albumin was determined and albumin synthesis was estimated by comparing this value with the estimated enrichment of precursor hepatic arginine Using this methodology, serum albumin concentration, synthesis, rate and plasma volume were measured when the young and elderly subjects had received an adequate protein intake (15 g · kg −1 for 7 days) or a low protein intake (04 g · kg −1 for 14 days) Serum albumin concentration was lower in the elderly at both levels of protein intake; protein intake did not affect this parameter in either age-group Plasma volume (per kg body weight) did not differ between young and old, but increased in both groups when they were given the low-protein diet, so that the total intravascular albumin mass increased in both age groups significantly in the case of the young, and was probably due to net transfer of albumin from the extravascular pool The fractional synthesis rate of the whole body albumin pool with adequate intake of protein was 40%/day in the young and 34%/day in the elderly This fractional rate was reduced significantly by giving the low-protein diet to the young subjects, but was not reduced in the elderly Absolute synthesis rates, calculated per kg body weight and per kg body cell mass, led to a similar conclusion Whole body protein synthesis was also estimated from urinary 15 N-urea enrichment using the Picou and Taylor-Roberts model Albumin synthesis as a percentage of whole body protein synthesis (5%–6%) was reduced in the young adults by giving the low-protein diet, but was unchanged in the elderly In conclusion, the rate of albumin synthesis in the young, but not in the elderly, is sensitive to changes in protein intake It is suggested that albumin synthesis in the elderly is controlled at a lower set point, which prevents its response to higher protein intakes
152 citations
TL;DR: In this article, the authors conducted a survey of the Namib dunes after a prolonged dry period (mean annual precipitation 14 mm) and after a high rainfall event (118 mm).
141 citations
TL;DR: In a test designed to evaluate learning ability rehabilitated rats of groups P and F were significantly less successful than normal rats, but more successful than rats of group W or rats of the original undernourished colony.
Abstract: 1. Rats which have been maintained for ten to twelve generations on diets of low protein value were rehabilitated in utero (group P), from birth (group F) and from 4 weeks of age (group W). 2. Group W showed little change in physique, behaviour or learning, indicating that for recovery to be effective refeeding must begin earlier. 3. Group F just failed to attain full physical recovery (90%) whereas group P overgrew by 18.6% in weight and 8.5% in length. 4. In a test designed to evaluate learning ability rehabilitated rats of groups P and F were significantly less successful than normal rats, but more successful than rats of group W or rats of the original undernourished colony. 5. Rehabilitation for a further two generations in groups F and P corrected any residual physical and behavioural defects but produced no further improvement on the Lashley (1938) jumping platform.
127 citations
TL;DR: The results suggest that low protein intake, rather than calorie deficiency per se, is primarily responsible for the reduction in filtration rate seen in this experimental model of chronic malnutrition.
Abstract: To determine the physiological basis for the low glomerular filtration rate in chronic malnutrition, micropuncture studies were performed in Munich-Wistar rats chronically pair-fed isocaloric diets of either low (group 1, nine rats) or high protein content (group 2, nine rats). Despite the absence of hypoalbuminemia, average values for single nephron and total kidney glomerular filtration rate were nearly 35% lower in group 1 than in group 2. Mean values for glomerular capillary and Bowman's space hydraulic pressures were essentially identical in the two groups, thereby excluding glomerular transcapillary hydraulic pressure difference as the cause for the low filtration rates in group 1 animals. On the other hand, average glomerular capillary plasma flow rate and glomerular capillary ultrafiltration coefficient were significantly lower (by approximately 25 and approximately 50%, respectively) in group 1 than in group 2. The fall in glomerular capillary plasma flow rate was the consequence of increased afferent and efferent arteriolar resistances. Plasma and erythrocyte volumes were found to be equal in five additional pairs of group 1 and group 2 rats. Thus, the substantial alterations in the ultrafiltration coefficient, glomerular capillary plasma flow rate, and renal arteriolar resistances responsible for the low filtration rate in group 1 animals were not merely a consequence of decreased circulating blood or plasma volumes. Mean values for glomerular cross sectional area were significantly lower in group 1 than in group 2 despite similar values for kidney weight in the two groups. This reduction in glomerular cross sectional area in group 1 rats is presumed to reflect a decrease in effective filtration surface area and therefore likely accounts, at least in part, for the decline in ultrafiltration coefficient observed in this group.Finally, since the daily caloric intake of group 2 animals was restricted because of pair feeding requirements tied to the group 1 rats, we studied a third group of seven rats (group 3) allowed an ad lib. intake of the same high protein diet as given to group 2 rats. Average values for single nephron glomerular filtration rate and its determinants were found to be indistinguishable between groups 2 and 3. These results suggest that low protein intake, rather than calorie deficiency per se, is primarily responsible for the reduction in filtration rate seen in this experimental model of chronic malnutrition.
126 citations
TL;DR: Results indicated that over separating distances of 5.4 cm 150 to 200 bands should be resolved and that considerable differences between two commercial carrier ampholytes exist, and Pharmalyte carrier Ampholytes from Pharmacia have better continuity and conductance over the range of pH 3–10 but require much higher field strengths to achieve maximal separation than do LKB Ampholines over a similar pH range.
Abstract: Polyacrylamide gel isoelectric focusing was carried out using 250 μm thick gels backed with polyester films at voltage gradients up to 460 V/cm. Peltier cooling was employed with berrylium oxide heat transfer plates to achieve adequate cooling. Visualization of low protein concentrations was obtained by the use of a highly sensitive silver staining technique. Results indicated that over separating distances of 5.4 cm 150 to 200 bands should be resolved and that considerable differences between two commercial carrier ampholytes exist. Pharmalyte carrier ampholytes from Pharmacia have better continuity and conductance over the range of pH 3–10 but require much higher field strengths to achieve maximal separation than do LKB Ampholines over a similar pH range.
110 citations
TL;DR: Dietary treatments did not affect the urinary excretion of copper, serum copper levels or the apparent absorption and retention of manganese by these subjects.
Abstract: Zinc, copper and manganese utilization were examined in eight adult males fed a low protein-moderate phosphorus diet (LPrMP), a low protein-high phosphorus diet (LPrHP), a high protein-moderate phosphorus diet (HPrMP) and a high protein-high phosphorus diet (HPrHP) during a 51-day balance study. The low and high protein diets contained 8.1 g and 24.1 g nitrogen daily, respectively. The moderate and high levels of phosphorus were 1,010 and 2,525 mg phosphorus daily. Subjects lost less zinc in the feces when fed the HPrMP diet than when fed the other three diets. The level of dietary protein and phosphorus all statistically affected fecal zinc excretion. Urinary zinc excretion was significantly greater when subjects consumed the high protein diets rather than the low protein diets. Apparent retention of zinc was greatest when subjects were fed the HPrMP diet rather than the other three diets. This effect was statistically attributable to the interaction between dietary protein and phosphorus. Serum zinc levels were significantly elevated when subjects consumed the high protein rather than the low protein diets. Serum zinc levels were correlated to urinary zinc excretion (r = 0.788, P< 0.001), apparent retention of zinc (r = 0.385, P< 0.05) and serum copper levels (r = 0.395, P < 0.05). Apparent absorption and retention of copper were significantly greater when subjects were fed the high protein rather than the low protein diets. They dietary treatments did not affect the urinary excretion of copper, serum copper levels or the apparent absorption and retention of manganese by these subjects.
94 citations
TL;DR: Evidence suggests that the phosphorylated form of enzyme I is more stable, and kinetics that are consistent with a bi bi Ping-Pong mechanism are suggested.
Abstract: Enzyme I of the phosphoenolpyruvate - sugar phosphotransferase system (PTS) has been purified to homogeneity from Escherichia coli. A merodiploid strain P650 which had an extra copy of the gene for enzyme I resulting in a twofold increase in the amount of activity was used. The enzyme is a dimer of 67 000 +/- 5000 molecular weight subunits. At low protein concentration and 4 degrees C the monomer predominates, while at room temperature the dimer predominates. At higher protein concentrations (2 to 10 mg) this reversible temperature-dependent association-dissociation is not found. Enzyme I has a pH optimum of pH 7.2, a Km for HPr of 9 +/- 3 microM, a Km for phosphoenolpyruvate of 0.18 +/- 0.04 mM, and kinetics that are consistent with a bi bi Ping-Pong mechanism. No allosteric regulation of kinetic activity has been found. The amino acid composition has been determined and the epsilon 1% 280 nm is 4.4. Evidence suggests that the phosphorylated form of enzyme I is more stable.
73 citations
TL;DR: Four groups of rats were used in a nutritionally-controlled study of effects of chronic ethanol consumption on brain membrane lipid composition, where changes may be adaptive responses to the fluidizing effect of ethanol on membranes.
50 citations
TL;DR: The relative hyperphagia, decreased efficiency of energy utilization and increased oxygen consumption and serum T3 concentrations in the lean rats fed the low-protein diet were consistent with the development of an adaptive thermogenesis, allowing the excess non-protein energy to be dissipated through excess heat production.
Abstract: Experiments were conducted to study the effects of a low protein-high carbohydrate diet on growth and thyroid function in obese and lean male and female Zucker rats. The nine feeding regimens included animals ad libitum fed either a 22% casein and 59% carbohydrate diet (control) or an 8% casein and 73% carbohydrate diet (low protein) and appropriate pair-fed groups to control for the lean rats eating less than the obese rats and the rats fed the low-protein diet eating less than those fed the control diet. The rats were 4 weeks old at the start of the experiment which lasted 7 weeks. Final body size, tibia length and nonfat dry mass of the lean rats were dependent primarily on the amount of protein consumed, whereas growth of the obese rats was related to total energy intake rather than to protein intake. The relative hyperphagia, decreased efficiency of energy utilization and increased oxygen consumption and serum T3 concentrations in the lean rats fed the low-protein diet were consistent with the development of an adaptive thermogenesis, allowing the excess non-protein energy to be dissipated through excess heat production. There was no evidence for such an adaptive thermogenesis in the obese rats. The suggestion that the obese rats were already overeating for protein and storing the excess energy as fat and that the decreased thyroid response might be part of a protective mechanism against overheating was discussed.
TL;DR: It is concluded that a suitable compromise would be an I value of 470 kJ/g N increasing by 10%/week, indicating that FCR was better at high protein levels and worse at low protein levels when the diets were fed on the lower plane of nutrition.
Abstract: 1. The effect of energy and protein intake on the growth, food efficiency and nitrogen retention of artificially-reared pigs was studied over three 8 d periods between 8-32 d of age in an experiment employing a 5 x 3 x 2 factorial design. The factors were initial energy: N value (I; 250, 355, 460, 565 or 670 kJ/g N), rate of increase of I at 8 d intervals (0, 12.5 or 25%) and plane of nutrition (three times daily to appetite or 75% of this intake). 2. The range of energy: N values was obtained by formulating five diets based on dried skim milk, lactose and casein and feeding appropriate combinations of two diets. The diets, which were pelleted, contained 100 g maize oil/kg and the gross energy content was approximately 20 MJ/kg. 3. N digestibility was high at all three age intervals, reaching 0.99 on the diet containing the highest dietary crude protein (N x 6.25) level. Metabolic faecal N excretion was found to be I.I g/kg dry matter (DM) intake. 4. Growth rate, feed conversion ratio (kg food intake/kg wt gain; FCR), N retention (NR) and the proportion of digested N retained (NR: apparent digested N (ADN)) were significantly (P less than 0.001) affected by I values at all age intervals and the responses were quadratic. Response curves were calculated by the least squares method and optimum values of I determined for each of the criteria. A constant energy: N value of approximately 400 kJ/g N was indicated by growth, FCR and NR optima but the NR:ADN value fell from 0.77 for the 8-16 d period to 0.60 for the 24-32 d period at this I value. It is concluded that a suitable compromise would be an I value of 470 kJ/g N increasing by 10%/week. 5. There was a significant interaction between plane of nutrition and I values on FCR between 16-24 d (P less than 0.001) and 8-32 d (P less than 0.01) indicating that FCR was better at high protein levels and worse at low protein levels when the diets were fed on the lower plane of nutrition.
TL;DR: In goats fed on a low-protein diet, the rumen is an important site of appearance of blood urea in the digestive tract, and it was verified that the principal mode of transfer ofBlood urea to theRumen was the direct diffusion through the wall of the Rumen.
Abstract: 1. An experiment was carried out with goats fed on a low-protein ration to clarify the importance of the rumen and significance of saliva in the appearance of re-cycled urea in the digestive tract during the final third of a once daily feeding regimen. The isotope-dilution method with [15N]urea and 15NH4Cl was used. 2. When the serum urea level was 58 mg N/l, the amount of urea transferred from the blood urea pool to the rumen ammonia pool was 48.6 mg N/h, which was estimated to be approximately 43% of the total amount of urea having appeared in the NH3 pool of the digestive tract. When the serum urea level was 106 mg N/l, the corresponding amount of NH3 was 77.7 mg N/h, which was estimated to be approximately 46% of this total amount. 3. The amount of saliva secreted was measured directly by the oesophageal fistula method. Salivary secretion serves as a mode of transfer of blood urea to the rumen NH3 pool. Then the ratio, salivary secretion:diffusion through the rumen wall during the final third of the cycle was calculated to be 1:4-1:6. 4. In goats fed on a low-protein diet, the rumen is an important site of appearance of blood urea in the digestive tract. It was verified that the principal mode of transfer of blood urea to the rumen was the direct diffusion through the wall of the rumen.
TL;DR: The results support the proposal that more aggregated forms of rat liver phosphofructokinase have a decreased Km value for fructose 6-phosphate when assayed with inhibiting concentrations of MgATP.
TL;DR: Mixtures of albumin and poly(ethylene glycol) (PEG) were used to elucidate some of the factors which influence the separation of macromolecules by thin-channel ultrafiltration and it was still possible to obtain efficient removal of PEG-4000 from albumin in spite of the adverse effects of protein adsorption.
TL;DR: It is concluded that 8 days of moderately severe protein deprivation significantly impairs erythropoiesis and leukocyte function in otherwise healthy individuals.
TL;DR: It was condluded that immunofixation is the preferred technique for the identification of monoclonal immunoglobulins.
TL;DR: It is concluded that the low protein turnover rates in the uremic population reflect the decreased protein-energy intake commonly found in such patients and that reduction of azotemia by chronic hemodialysis may improve whole body transport at a given energy intake.
TL;DR: Patients responded similarly to the two diets; however, the group receiving ketoacids had a significantly lower glomerular filtration rate and there was improvement in calcium and phosphate metabolism with ketoacid treatment.
TL;DR: It is suggested that the decreased insulin secretory response of islets from protein malnourished animals may be due to a diminished number of glucose recognition sites on the beta cells.
Abstract: Male weanling rats were fed either 4 or 16% (control) protein diets for 10 to 12 weeks The animals were administered an iv injection of 30% glucose solution (3 g/kg body wt) and glucose tolerance was determined The glucose tolerance in rats fed low protein diets was not significantly different from that of the control rats, indicating that clearance of high blood glucose levels in the animals fed low protein diets was not affectedUsing a collagenase digestion technique, islets of Langerhans were isolated from another set of animals fed 4% or control diets When these islets were perifused with a medium containing glucose, there was a typical biphasic insulin secretory response The isolated islets from low protein fed rats exhibited considerably low insulin secretory response when exposed to medium containing 167 mM glucose (300 mg/dl), although no difference was found in the pancreatic insulin content of normal and low protein fed rats This indicates that decreased insulin secretion could
TL;DR: It is concluded that ammonia, a direct substrate for urea synthesis, may control the concentrations of both Ornithine and acetylglutamate in the liver, directly or indirectly, although perfused liver lacks some factors that keep the concentration of ornithine at the in vivo level and cause its increase in response to ammonia.
01 Sep 1980
TL;DR: Adsorption chromatography proved to be the most effective method to concentrate, extract and partially purify the thermostable neutral proteases produced by Bacillus stearothermophilus NCIB 8924 and NRRL B-3880.
Abstract: Purification procedures for extracting and concentrating thermostable neutral proteinases using vacuum evaporation and ammonium sulfate precipitation, or adsorption chromatography on amberlite XAD-7 resin were compared. Adsorption chromatography proved to be the most effective method to concentrate, extract and partially purify the thermostable neutral proteases produced by Bacillus stearothermophilus NCIB 8924 and NRRL B-3880. Proteases can also be extracted from large volumes of culture media containing only weak proteolytic activity and a low protein concentration. Final purification of the thermostable neutral proteases was performed with an established affinity chromatography method. The method seems to be suitable for scaling up.
TL;DR: Two molecular forms of alpha-galactosidase synthesized constitutively by Bacillus stearothermophilus, strain AT-7, have been purified and suggest that both enzymes consist of four subunits.
Abstract: Two molecular forms of α-galactosidase (EC 32122) synthesized constitutively by Bacillus stearothermophilus, strain AT-7, have been purified α-Galactosidase I (with the substrate p-nitrophenyl α-D-galactopyranoside (PNPG)) has a pH optimum of 6 and a half-life at 65 °C of > 2 h at low protein concentration α-Galactosidase II has a pH optimum of 7 with PNPG and a half-life at 65 °C of about 3 min The isozymes also differ with respect to their Km with PNPG and melibiose Both enzymes are inhibited competitively by D-galactose, melibiose, and Tris With the β-glycosides cellobiose and lactose either noncompetitive or mixed-type inhibition is observed, with the pattern dependent on both the pH and the isozyme The two isozymes have similar Arrhenius activation energies (about 20 kcal/mol, 1 kcal = 4184 kJ) Their molecular weights, estimated by disc gel electrophoresis, are α-galactosidase I, 280 000 ± 30 000 and α-galactosidase II, 325 000 ± 15 000 Dodecyl sulfate gel electrophoresis gave a single ba
TL;DR: Results indicate that as long as Zn(II) remains bound to the zymogen, autocatalytic activation is inhibited and removal of this ion, by dilution of the protein or by chelation, initiates autoactivation.
Abstract: Mouse submandibular gland nerve growth factor (NGF) is a 116 000 molecular weight protease with a high degree of specificity for certain lysyl and arginyl bonds. Thie protein can activate plasminogen and it is also a member of the general class of serine proteases [Orenstein, N. S., Dvorak, H. A., Blanchard, M. H., & Young, M. (1978) Proc. Natl. Acad. Sci, U.S.A. 75, 5497]. As isolated, NGF is an enzymically inactive zymogen. Upon dilution from high to very low protein concentrations or upon treatment with EDTA, the zymogen undergoes autocatalytic activation. Atomic absorption spectroscopy measurements reveal that NGF contains 1 g-atom of tightly bound Zn(II) per mol. Reaction of the fully autoactivated protease with [3H]DFP yields 1 mol of labeled serine per mol of enzyme. All results indicate that as long as Zn(II) remains bound to the zymogen, autocatalytic activation is inhibited. Removal of this ion, by dilution of the protein or by chelation, initiates autoactivation. The physiologic purpose of this unusual reaction is not known but it may be that Zn(II) serves to act as a control ion which keeps the protein in an inactive form (the zymogen) until it recognizes its naturally occurring substrate.
TL;DR: The data suggest a crude protein concentration of 115 g/kg dry matter as a requirement for high fibre diets supplemented with fishmeal, when fed to yearling cattle.
Abstract: Three experiments, each consisting of a feeding trial plus a digestibility and nitrogen retention study, compared long barley straw with rolled barley as basal diets and oat hulls with maize starch as energy supplements for yearling dairy cattle. The protein ontent of the diets was varied by the addition of flshmeal. Growth rates were reduced by the dietary combination of high fibre and low protein, so that diets rich in straw, or containing a supplement of oat hulls, gave a large response to a supplement of fishmeal compared with low straw or maize starch supplemented diets. The data suggest a crude protein concentration of 115 g/kg dry matter as a requirement for high fibre diets supplemented with fishmeal, when fed to yearling cattle. Retention of nitrogen reflected the pattern of live-weight gain. Molar proportions of VFA were affected by changes in the roughage: concentrates ratio, except where energy and protein intakes were both low. Barley straw was of a higher nutritive value than oat hulls.
TL;DR: The large enhancement of the green luminescence of terbium ion which occurs on binding to porcine and bovine trypsins and to bovines α-chymotrypsin has been used to study the calcium binding sites of these enzymes.
TL;DR: The results from these experiments indicate that at low protein levels both lines were equally efficient, but, as the level of protein was increased, the low line was increasingly more efficient while the high line became less efficient.
TL;DR: A vinasse, originating as the condensed molasses residue from the microbial production of citric acid, was chemically analyzed and given to growing pigs to determine its protein and energy value.
TL;DR: The findings of a clinicopathological and biochemical study of epidermal cysts and a review of the relevant literature are presented, showing that inflammation in these lesions was usually aseptic unless there was a communication between the cyst cavity and the exterior.
Abstract: The findings of a clinicopathological and biochemical study of epidermal cysts and a review of the relevant literature are presented. A punctum was found in 40% of 34 epidermal cysts that were studied in detail. The findings of the histological study were in favour of the punctum being the orifice of an obstructed hair follicle from which at least a proportion of the epidermal cysts are likely to develop. The biochemical analysis of the contents of the cysts revealed a very low protein and lipid content, thus ruling out any "sebaceous' contribution. Bacteriological study of clinically inflamed cysts showed that inflammation in these lesions was usually aseptic unless there was a communication between the cyst cavity and the exterior.