bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of amino acid analogues on protein synthesis and degradation in isolated cells
Authors: Knowles S. E. , Ballard F. J. 
Published: September 2005

1. Naturally-occurring and synthetic analogues of phenylalanine, tyrosine, histidine, arginine, proline, tryptophan and the sulphur amino acids have been tested in rat reticulocytes and in the Reuber H35 hepatoma for effects on protein synthesis and protein degradation and on the heat lability of phosphoenolpyruvate carboxykinase (EC4.1.1.32) in the hepatoma cells. The experiments were designed to test whether the analogues could be incorporated into mammalian proteins and whether the resultant proteins would be degraded at an accelerated rate.2. Several analogues, including thiazolylalanine, triazolalanine and selenocystine both stimulated protein synthesis and produced labile protein in reticulocytes. Other analogues, such as dihydroxyphenylalanine, thioproline and pipecolic acid accelerated protein breakdown but probably indirectly via an inhibition of protein synthesis. Azetidine-2-carboxylic acid had the largest effect on protein breakdown in reticulocytes.3. Labile protein was produced in hepatoma cells incubated in the presence of azetidine-2-carboxylic acid, canavanine, indospicine, triazolalanine, 2-, 3- and 4-fluorophenylalanine. These same analogues, together with 3, 4-dehydroproline, β-2-thienylalanine, dihydroxyphenylalanine, histidinol, 5- and 6-fluorotryptophan, selenocystine and selenomethionine produced heat-labile phosphoenolpyruvate carboxykinase. Enzyme induced in the presence of selenomethionine or indospicine showed the largest increases in heat lability, and for these analogues equimolar concentrations of methionine and arginine respectively were needed to nullify the enzyme abnormality.4. The toxicity of the same naturally-occurring analogues has been discussed in terms of their ability to be incorporated into cell proteins.
Absence of immunological hypersensitivity to dietary cow's-milk proteins in infant rabbits
Authors: Kilshaw P. J. , Henschel M. J. , Coates M. E. 
Published: September 2005

1. Rabbits hand-reared on a diet based on cow's milk frequently experience convulsive and sometimes fatal reactions to their feed. These have been thought to be caused by immunological hypersensitivity to cow's milk.2. This explanation has been re-examined and found to be untenable.
Biliary lipids, bile acids and gallstone formation in hypovitaminotic C guinea-pigs
Authors: Jenkins S. A. 
Published: September 2005

1. Hypovitaminotic C guinea-pigs fed on a high-cholesterol diet for 5 weeks developed gallstones (810 mg cholesterol/g) whereas no concretements were observed in vitamin C-replete animals.2. Scanning electron microscope studies of the three types of gallstone observed in the gallbladders of vitamin C-deficient animals showed them to be composed of randomly-arranged needle-shaped or laminated crystals of cholesterol.3. The hepatic bile of gallstone-forming animals had a higher cholesterol concentration and lower bile acid content, the latter being principally due to a reduction in the chenodeoxycholic fraction, than the bile of vitamin C-replete animals.4. No significant difference was observed between the volume of bile secreted by hypovitaminotic C and vitamin C-replete animals, but due to the qualitative changes in bile composition, gallstone formation was associated with an increased biliary secretion of cholesterol and a reduced secretion of bile acids.
Amino acid requirements of the breeding sow
Authors: Sohail M. A. , Cole D. J. A. , Lewis D. 
Published: September 2005

1. Two experiments, involving six lactating Landacre x (Landrace x Large White) sows were undertaken to study the lysine requirement of the lactating sow and to identify the second limiting amino acid by means of interpretation of plasma amino acid and blood urea levels.2. A basal diet composed mainly of equal amounts of ground barley and ground wheat supplemented with mineral and vitamin mixtures was used. This diet was supplemented with synthetic amino acids (lysine, threonine, tryptophan, methionine and isoleucine).3. Plasma amino acid and blood urea values showed a close agreement and indicated that lysine intake above 38.4 g/d was in excess of the requirement level.4. Plasma amino acid values suggested tryptophan to be the second limiting amino acid whereas blood urea values suggested threonine to be the second limiting amino acid.
The accretion of copper and of zinc by the foetuses of prolific ewes
Authors: Williams R. B. , McDonald I. , Bremner I. 
Published: September 2005

1. The amounts of copper and zinc in the foetuses of ewes carrying from one to four lambs were measured at different stages of gestation and estimates were made of the amounts of these metals in their livers.2. The accretion of Cu and Zn could be described by growth equations of the Gompertz form, from which could be derived estimates of the instantaneous and fractional rates of deposition of these metals in the foetal body.3. Between the 80th and 144th day of gestation the instantaneous rates of deposition of the metals increased exponentially, and at the end of pregnancy were calculated to be 0.24 and 2.0 mg Cu and Zn/d respectively in the triplet lamb foetus. The corresponding total accretions were estimated to be 10 and 69 mg respectively.4. The fractional rates of live-weight gain and of deposition of Cu were similar and decreased at similar rates; that of Zn deposition decreased much more slowly.5. The proportion of whole-body Cu estimated to be in the liver was always greater than 50 %. The amount of Zn in the liver remained constant and contributed 72 % of the total body Zn at 80 d but only 8 % at 144d.6. The relative amounts of Cu and of Zn accrued per unit body-weight gain were not constant during the development of the foetus. As foetal numbers increased the amounts of each metal deposited in the foetus decreased more rapidly than did foetal weight.7. The results are discussed in relation to the demands for Cu and Zn during pregnancy in sheep.
The effect of 1-α-hydroxycholecalciferol on calcium and phosphorus metabolism in the lactating ewe
Authors: Braithwaite G. D. 
Published: September 2005

1. The effect of 1-α-hydroxycholecalciferol (1 α-OH-D3) on calcium and phosphorus metabolism has been studied in ewes at peak lactation by a combination of a mineral balance and a radioisotope technique.2. The rate of Ca absorption was substantially higher in the treated ewes than in controls. The rates of endogenous loss of Ca into urine, faeces and milk, however, were only slightly higher.3. In consequence, the net retention of Ca was increased and the loss of skeletal reserves of Ca normally associated with peak lactation, prevented.4. Although the rate of bone accretion increased slightly, the increase in skeletal retention of Ca resulted mainly from a decrease in the rate of bone resorption.5. This finding conflicts with the generally held belief that bone resorption is increased by cholecalciferol treatment.6. The rates of apparent absorption and retention of P were increased by the treatment probably as a result of a direct effect of the 1α-OH-D3on P absorption.7. These results provide a possible explanation of the beneficial effect of 1α-OH-D3in preventing parturient paresis (milk fever) in the dairy cow.
Metabolism of dietary fibre components in man assessed by breath hydrogen and methane
Authors: Tadesse K. , Eastwood M. A. 
Published: September 2005

1. Breath hydrogen and methane were measured in eight normal individuals after acute and separate administration of different chemical components of dietary fibre.2. Hemicellulose, raffinose and lactulose increased H2 production, while cellulose, pectin and lignin did not. Methane production was found to be individual and unaffected by any of the substances. Differences in physical properties of the same chemicals appear to have no influences on H2 and CH4 production.
Urinary excretion of aflatoxin M1 after administration of aflatoxin B1 in sucrose- or starch-rich diets
Authors: Wise A. , Suzangar M. , Messripour M. , Mohammadi J. 
Published: September 2005

1. Male Sprague–Dawley rats were given 630 g/kg sucrose or starch with 2 mg/kg aflatoxin B1 for periods of 75, 145 and 200 d, and the 24 h urinary excretion of aflatoxin M1 was measured.2. Less aflatoxin M1 was excreted by the rats fed on the sucrose-rich diet compared to those fed on the starch-rich diet. This difference was especially marked when expressed per g metabolizing tissue.3. It is concluded that sucrose probably decreases the activity of aflatoxin B1 metabolism in a similar way to its previously found effect on the drug-metabolizing enzyme.
Nutritional effects of field bean (Vicia fabaL.) proteinase inhibitors fed to rats
Authors: Abbey Bene W. , Neale R. J. , Norton G. 
Published: September 2005

1. Weanling rats were fed on purified-casein diets containing active and inactive (autoclaved) field bean (Vicia fabaL.) proteinase inhibitors (PI) at levels of 1.25, 2.5, 5.0 and 10 g/kg. Diets containing raw-and autoclaved-field-bean meal (FBM) were also given. The body-weight gain, protein efficiency ratio (PER); i.e. the ratio of the live weight gain in g/g of protein consumed and apparent nitrogen digestibility were determined 7, 14 and 21 d after the start of the trial.2. Significant growth depression (P< 0.001) was observed in rats given diets containing 2.5 g/kg PI (27–35%). In rats fed on raw FBM growth depression was severe after 7 d (57%).3. Food intake was depressed at PI inclusion levels of 5 g/kg and higher between 14 and 21 d.4. PER was depressed significantly (33–44%) in rats given diets containing the active PI at all levels after 7 d. The protein utilization of all casein diets was higher than that of the FBM diets.5. Apparent N digestibility was depressed in rats fed on diets containing 10 g/kg PI by 9 and 7% at 14 and 21 d respectively. The N digestibility of both raw and heated FBM was similar at approximately 84%.6. It was concluded that the PI are not the main factors responsible for the growth depression observed when raw FBM is fed to rats.
Absorption of lactulose from mammalian gastrointestinal tract
Authors: Evered D. F. , Sadoogh-Abasian F. 
Published: September 2005

1. The disaccharide lactulose (galactosyl-β-1,4-fructose) was poorly absorbed from rat small intestine in vitro and human mouth in vivo.2. These results confirm indirect clinical evidence of poor absorption from the intestine.3. The presence of calcium ions, or absence of sodium ions, had no effect on lactulose absorption from the buccal cavity.4. The presence of ouabain, or absence of Na+, did not decrease the absorption of lactulose from small intestine.5. It is thought that the mode of transport, in both instances, is by passive diffusion with the concentration gradient.
Artificial rearing of pigs
Authors: Newport M. J. 
Published: September 2005

1. The requirement of the artificially-reared pig for crude protein (nitrogen × 6.38; CP) was estimated between 2 and 28 d of age. The pigs were given one of five diets, each containing 270 g soya-bean oil/kg and either dried skim-milk and dried whey in different proportions to supply 150, 180, 210 or 240 g CP/kg, or dried skim-milk alone which supplied 270 g CP/kg. The energy content of the diets was approximately 22 MJ digestible energy/kg.2. The diets were obtained as spray-dried powders, reconstituted in water, and fed as a liquid containing 200 g DM/l. The pigs were fed at hourly intervals to a scale based on live weight.3. N retention (g/d per kg live weight) and the proportion of CP in the carcass indicated a CP requirement of 240 g/kg for pigs from 2–28 d of age.There was no significant difference (P > 005)in performance between levels of dietary CP of 2.10, 240 or 270 g/kg. Although there was no increase in the proportion of CP in the carcass above a dietary CP level of 240 g/kg, a linear reduction in the proportion of lipid occurred as dietary CP level increased from 150 to 270 g/kg. Mortality, which was associated with scouring, was increased when the diet contained less than 210 g CP/kg.4. There was a linear response in N retention to the level of CP in the diet at 7 d of age, whereas at 19 d of age, N retention reached a maximum with 240 g CP/kg diet, suggesting that the CP requirement may be greater during the first week of life.5. Excretion of endogenous N in the urine was found to be 250 mg N/d per kg live-weight0.75 in pigs between 7 and 19 d of age (20–6.4 kg live weight).
The effect of varying the quality of dietary protein and energy on food intake and growth in the Zucker rat
Authors: Radcliffe J. D. , Webster A. J. F. 
Published: September 2005

1. Food intake and rates of protein, lipid and energy deposition were measured for lean and obese (fatty) Zucker rats offered to appetite from 34 d of age to slaughter at 66 d of age, one of sixteen semi-synthetic diets. Measurements were also made of the digestibility of dietary protein and the metabolizability of dietary energy. Total carcasses were analysed for protein and lipid, and body energy was calculated thereby. Changes in body constituents were calculated by the comparative-slaughter technique.2. In Expt 1, four rats of each phenotype and sex were offered one of four diets, each of which contained either 150 or 300 g casein (150 C and 300 C respectively)/kg and either 150 or 300 g cellulose (150 CELL and 300 CELL respectively)/kg (diets 150 C/150 CELL, 150 C/300 CELL, 300 C/150 CELL and 300 C/300 CELL. As expected, males ate more and had higher rates of protein deposition than female animals of the same phenotype on all diets. These sex differences were greater for the lean phenotype. The results for animals in this experiment are presented with, and discussed in relation to, those obtained previously for animals of both sexes fed on cellulose-free diets having these two levels of casein.3. In Expt 2, four female animals of each phenotype were fed one of twelve semi-synthetic diets, each of which contained casein, gluten or zein at one of the following levels (g crude protein (nitrogen × 6.25)/kg diet): 93, 132, 267 or 627. On all diets containing zein both fatty and lean rats had similar, low food intakes and failed to grow. Fatty rats fed on diets containing casein or gluten had higher rates of food intake, weight gain, lipid and energy deposition than leanrats, but similar rates of protein deposition. Rats fed on diets having the two lower levels of casein ate more and grew better than animals of the same phenotype fed on the two corresponding diets containing gluten but at higher protein levels differences in food intake and growth attributable to differences in protein quality disappeared and furthermore, the rate of protein deposition became similar and maximal for both phenotypes.4. The results from both experiments are discussed in relation to previous work on appetite control in the Zucker rat. It appears that fatty and lean rats eat during growth to attain the maximal rate of protein deposition of which they are capable. The rate of lipid deposition would appear to be of no importance in the food intake regulation of animals depositing protein maximally.5. Rats given diets that fail to support maximal rates of protein deposition appear to regulate their intake of digestible energy rather than that of digestible protein. They do not overeat protein-deficient diets in order to acquire sufficient protein for maximal growth although the factors that induce satiety in these animals are unknown.
Some effects of sulphur intake on molybdenum metabolism in sheep
Authors: Grace N. D. , Suttle N. F. 
Published: September 2005

1. To investigate the effects of sulphur intake on molybdenum metabolism in sheep, ewes were given intakes of 0.3 or 3.5 mg Mo and 0.98, 1.33, 1.73 or 3.23 g S/d in a 2 × 4 factorial experiment with two replicates lasting 35 d. 99Mo with 0.1 mg carrier Mo was infused intravenously for the last 14 d and, when 99Mo concentrations in urine and faeces had attained plateaux (days 11–14), stable Mo and 99Mo balance trials were conducted; samples of blood and rumen contents were taken principally for studies of Mo distribution.2. Increases in S intake caused the following changes in Mo metabolism; absorption decreased, urinary and faecal endogenous excretion decreased and retention increased; Mo concentrations in rumen contents decreased but the predominant association with the solid phase was unaffected; Mo concentrations in plasma decreased, but a higher proportion was associated with the protein fraction; Mo in protein-free plasma became apparently less ultrafiltrable at the glomerulus.3. The pattern of response to S for each factor was generally curvilinear, the first increment in S intake having by far the greatest effect. The effect of S was generally greatest at the higher Mo intake.4. It is suggested that the manifold effects of S on Mo metabolism are related to a common interaction in the rumen leading to the formation of Mo-complexes, possibly thiomolybdates, which are poorly absorbed but even more poorly excreted.
Studies on digestion and absorption in the intestines of growing pigs
Authors: Low A. G. 
Published: September 2005

1. Digesta were collected from seventeen pigs initially of 30 kg live weight fitted with single re-entrant cannulas in either the duodenum, jejunum or ileum. A further twenty-four pigs were used in a conventional digestibility trial.2. The pigs received three types of diet containing: barley, fine wheat offal, white fish meal, minerals and vitamins (diet BWF); starch, sucrose, maize oil, cellulose, minerals and vitamins and either groundnut (diet SSG) or casein (diet SSC).3. Amino acids were measured in samples representative of the digesta flow in 24 h periods and in the faeces collected in 5 d periods.4. For each diet the total flow in 24 h periods in the duodenum for aspartic acid, threonine, serine and glycine exceeded or equalled intake, while the amounts of the other amino acids were usually rather less than intake.5. For each diet in the jejunum, the amounts of glycine and cystine exceeded intake in 24 h periods, while methionine, arginine and tyrosine were the most rapidly absorbed amino acids anterior to the cannula site. On average 0.22, 0.25 and 0.31 of the dietary amino acids were absorbed anterior to the cannula site for diets BWF, SSG and SSC, respectively.6. For each diet in the ileum, the least apparently absorbed dietary amino acids were glycine and cystine. On average 0.81, 0.83 and 0.95 of the dietary amino acids were absorbed anterior to the cannula site for diets BWF, SSG and SSC, respectively.7. There was net disappearance of most amino acids in the large intestine, but some net accumulation occurred in this region.8. The results are discussed in relation to the amino acid composition of endogenous secretions (particularly glycine in bile), protease and peptidase specificity, free amino acid absorption and the role of the microflora in the large intestine.
Carotid or jugular amino acid infusions and food intake in the cockerel
Authors: Tobin G. , Boorman K. N. 
Published: September 2005

1. Infusions of histidine into the carotid arteries of cockerels receiving a histidine-limiting, imbalanced diet caused an increase in food intake, whereas similar infusions into the jugular veins did not.2. Infusions of lysine into the carotid arteries or jugular veins of young cockerels receiving a balanced, low-protein diet caused decreases in food intake. There was evidence of a more marked effect of carotid infusion.3. The mechanisms of food intake regulation by amino acids in mammals are applicable to birds and excesses of single amino acids do seem to affect food intake directly.
Seasonal variation in the effect of dietary RNA on criteria of energy homoeostasis in the rat
Authors: Heaf D. J. , Peers D. G. , Davies J. I. 
Published: September 2005

1. RNA was administered to rats as part of a meal while standardizing food intake and minimizing the effects of psychological stress and diurnal metabolic rhythms. It was demonstrated that circulating levels of glucose and free fatty acids (FFA) in the animals, which were deprived of food for 48 h, were responsive to orally administered caffeine.2. Inclusion of RNA in the diet slightly but consistently reduced the normal postprandial hyperglycaemia. Its effect on plasma FFA was variable although statistically significant in some experiments. The differences between RNA- and control-fed animals were not attributable to differences in the rate of passage of digesta along the gastrointestinal tract.3. Evidence was obtained that the variability in the FFA response was related to a seasonally-dependent change in the state of the animals. The synchronizer (‘Zeitgeber’) responsible for this change was not identified and no satisfactory way of suppressing its effect was found.4. The present findings, taken in conjunction with those of previous workers, suggest that there is a seasonal influence on the sympathetic nervous system manifesting itself as a variable susceptibility to arousal or excitation.
Estimates of maintenance requirement of growing lambs
Authors: Thomson D. J. , Fenlon J. S. , Cammell S. B. 
Published: September 2005

1. Total body energy retention (ER) and metabolizable energy intake (MEI) values from experiments with 231 lambs (Suffolk ♂× (Border Leicester ♂× Cheviot ♀) ♀) housed indoors and given thirteen forage diets were used to estimate the metabolizable energy (ME) required for maintenance.2. ER was measured using the comparative slaughter technique, and the lambs were fed at several planes of nutrition above maintenance between 2 and 5 months of age.3. The daily ER and MEI results were scaled to live weight (kg0.75) and linear regression lines fitted to the values for individual diets. Extrapolation of the fitted lines to zero ER gave estimates of maintenance requirement ranging from 141 to 466 kJ ME/kg0.75 per d and values for the efficiency of utilization of ME for growth and fattening (kf) of 0.25–0.53 (mean 0.39).4. An alternative analysis constrained the estimated maintenance requirement to be the same for all diets. An iterative search procedure indicated minimal residual variation at 339 kJ/kg0.75 per d. This common value of ME for maintenance gave kf values ranging from 0.30 to 0.54 (mean 0.39).5. The implications of the technique were considered togethe with some discussion of the variability of the estimate. Allowing the minimum RSD to vary by 10% gave a maintenance requirement of between 231 and 408 kJ/kg0.75 per d.
Body growth, puberty and undernutrition in the male guinea-pig
Authors: Slob A. Koos , Vreeburg J. T. M. , Van Der Werff Ten Bosch J. J. 
Published: September 2005

1. Male guinea-pigs were assigned to four different groups at birth. The heaviest group of animals was severely undernourished from 21 d of age (weight gain: 1.2 g/d v. 10 g/d for normally-fed animals).2. At 35, 45, 55 and 65 d of age in normally-fed animals, and at 45 and 55 d of age in undernourished animals, blood testosterone levels were determined by radioimmunoassay, epididymidal tissue examined for the presence of spermatozoa and testes sectioned for rating of spermatogenesis using light microscopy.3. Sexual maturity in terms of potential fertility (spermatozoa in the epididymis) was reached by all normally-fed animals between 45 and 55 d of age. High birth-weight animals had a higher incidence of the most advanced stages of spermatogenesis than low birth-weight ones at the various ages studied. In the undernourished animals spermatogenesis was clearly delayed.4. Plasma testosterone concentrations were already in the adult range at 35 d and independent of age and birth-weight. The undernourished animals, however, had very low levels. Maintenance of spermatogenesis seemed compatible with low plasma levels of testosterone.5. It is concluded that the timing of testicular development seems to be determined by the time the animals are born and appears to be unaffected by severe undernutrition from 21 d of age.