bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms of heat damage in proteins
Authors: Hurrell R. F. , Carpenter K. J. 
Published: May 2005

1. Analyses have been made of materials in which proteins were caused to react with sugars so as to cause a severe fall in their nutritionally available lysine content as assayed with both rats and chicks.2. With materials in which the reactions had proceeded under mild conditions (37°), the direct use of either fluorodinitrobenzene (FDNB),o-methylisourea or sodium borohydride to measure selectively those lysine units which had not engaged in Maillard reactions gave similar values which, in turn, appeared to reflect the full extent of the nutritional damage.3. Analysis by a procedure using trinitrobenzenesulphonic acid (TNBS), or the use of FDNB indirectly to measure ‘bound lysine’ failed to indicate the full extent of the Maillard reaction in mildly heated materials, although the same procedures did appear to do so when applied to materials in which sugar and proteins had been allowed to react at a higher temperature.4. With a pure protein and with fat-extracted, dried muscle that had been severely heated, all the procedures for measuring reactive lysine gave similar results, with the exception of the procedure using sodium borohydride which proved ineffective in measuring the type of damage that had occurred in these materials.5. The findings are discussed in relation to the nature of the reactions believed to take place in different types of heat damage.6. Suggestions are made of the types of materials with which different procedures can be satisfactorily used. The direct FDNB procedure and that usingo-methylisourea appeared to be applicable to all our samples.
The short-term response to a drink of milk, lactose or casein in children with apparently normal gastrointestinal tracts
Authors: Rossiter Mary A. , Palmer T. , Evans K. , Wharton B. A. 
Published: May 2005

1. Drinks of milk, lactose and casein were given to children who, though suspected of having malabsorption, were subsequently found to have normal gastrointestinal tracts. The plasma concentrations of glucose, amino acids, urea and insulin following these drinks were measured. The results can probably be taken to represent control values when investigating children with gastrointestinal or metabolic disorders.2. The rise in plasma amino acids after giving casein and the rise in plasma glucose after giving lactose were greater than those after giving equivalent amounts of milk.3. The absorption of an individual food constituent and its uptake by the tissues are influenced by the presence of other food constituents so that ‘tolerance tests’ with individual nutrients may not be truly physiological.
Protein quality of feeding-stuffs
Authors: Carpenter K. J. , Woodham A. A. 
Published: May 2005

1. Twelve commercial samples of high-protein feeding-stuffs, six of them fish meals, were used for a study of the reproducibility of chemical, microbiological and biological assay values for individual amino acids. Comparisons were also made of results obtained by different methods for the same amino acid.2. For lysine there was quite good agreement between the results from the different laboratory tests for ‘available’ lysine. The values for ‘total’ lysine were, on average, 10 % higher than those for ‘available’ lysine.3. For methionine the correlations between the chick assay and each of the laboratory tests were similar.4. The results from the ‘total protein efficiency’ test of over-all protein quality, using chicks, showed a close correlation with the results of lysine or methionine assays according to which of the two amino acids was most deficient.5. The results with tryptophan were difficult to interpret and no recommendations could be made as to procedures suitable for general use.6. Although most of the present samples proved to be of good quality, only screening of a much larger number of samples will reveal to what extent commercial protein concentrates of low availability are still liable to come onto the market.
Immunohistochemical detection of changes in growth hormone cells in rat pituitaries in protein deficiency
Authors: Drummond Therese 
Published: May 2005

1. An immunohistochemical method was used to study the effect of a low-protein diet on growth hormone (GH) cells in the pituitaries of developing rats. The deficient diet (80 g protein/kg) was administered during gestation and lactation, or during the time after weaning until 90 d of age, or during both periods.2. GH-cell changes were much more striking in males than in females.3. In males, GH-producing cells were usually reduced in size and number in all treatments. The effect was most intense when protein deprivation occurred throughout gestation and sucking, and continued until 90 d of age, but it was also evident in animals given the low protein diet only after weaning. Recuperation appeared to be almost complete when offspring of deprived dams were fed on a normal diet after weaning.4. It is concluded that a low-protein diet reduces the amount of GH in the rat pituitary in a way similar to that with a protein-free diet.
Metabolic studies in rats of [75Se]selenomethionine and of 75Se incorporated in vivo into rabbit kidney
Authors: Thomson Christine D. , Stewart R. D. H , Robinson Marion F. 
Published: May 2005

1. [75Se]selenomethionine was administered to four rabbits and after 4 d their kidneys were removed and homogenized. The long-term fate in rats of an oral dose of this kidney homogenate (RK-75Se) was compared with that of an oral dose of [75Se]selenomethionine mixed with unlabelled rabbit kidney homogenate.2. Urinary and faecal radioactivities were measured during the 1st week and whole-body radioactivity was determined for 10 weeks. Rats were killed at weekly intervals for 4 weeks for analysis of tissue distribution of 75Se.3. Intestinal absorption of RK-75Se was 87%; that of [75Se]selenomethionine was 91%. Urinary excretion of absorbed RK-75Se was 13·3% and that of [75Se]selenomethionine was 7·6%, in the 1st week.4. Whole-body retention of 75Se was greater for [75Se]selenomethione than for RK-75Se but after the 1st week decreased at a similar rate in both groups. Tissue distribution of retained 75Se was also similar in both groups.5. The initial utilization of 75Se in rabbit kidney is different from that of [75Se]selenomethionine. However, after the 1st week 75Se from these sources appears to be metabolized similarly, suggesting that Se from both is ultimately incorporated into the same metabolic pool.
Seasonal and nutritional effects on serum proteins and urea concentration in the reindeer (Rangifer tarandus tarandus L.)
Authors: Hyvärinen H. , Helle T. , Väyrynen R. , Vayrynen P. 
Published: May 2005

1. The effects of seasonal conditions and nutrition on serum proteins and serum urea concentrations were studied in female reindeer and reindeer calves in Finland. With the exception of one group in winter, the reindeer were roaming wild in the forests. This one group was kept in captivity, out of doors, on a comparatively high nutritional plane. One group lived wild during the winter in very poor nutritional conditions.2. A very clear seasonal variation in the serum protein and urea concentration was found. The serum protein concentration was low in late winter and increased rapidly during the summer, being high in the autumn. The serum urea concentration was also low in the winter and high in the summer. In the autumn, however, the serum urea concentration was again low.3. Changes in the serum protein concentration were normally associated with the serum globulins. Only in the very poor-nutrition group did the albumin content decrease significantly. As a result of the large changes in the concentration of serum globulins, there were also considerable changes in the albumin: globulin ratio.4. The serum protein concentration was much lower in the reindeer calves than in the adult reindeer. The concentration of globulins in particular was much lower than in the adults.
The effect of retinol and retinoic acid on physiological and biochemical changes in retinol-deficient rats
Authors: Krause R. F. , Beamer K. C. , Mccormick A. M. , Canterbury R. J. , Tryfiates G. P. 
Published: May 2005

1. The effects of retinol and retinoic acid supplementation of retinol-deficient rats were studied for a variety of metabolic processes shown to be affected by retinol deficiency.2. Retinol-deficient rats were found to have decreased body-weight, liver and testes weights, a degeneration of testicular germinal cells, an increased incorporation of labelled choline into liver and testes phospholipids, an increased protein synthetic activity (in vitro) of liver ribosomes, an increased transfer-RNA methyltransferase activity in liver and a decreased activity in testes, an increased DNA content of testicular nuclei, and a decreased uptake of [3H]thymidine by testicular nuclear DNA.3. In retinol-deficient rats supplemented for 8 weeks with retinol these changes were reversed, measurements returning to control levels.4. In retinol-deficient rats supplemented for 8 weeks with retinoic acid all changes were reversed except those in the testes.5. Testicular signs of retinol deficiency appeared to be delayed when retinoic acid was added to the retinol-deficient diet of weanling rats. This suggests a sparing action of retinoic acid on the rat's utilization of retinol.6. Suggestions are offered as to why retinoic acid will support growth and development but not spermatogenesis in the rat.
The use of three dye-binding procedures for the assessment of heat damage to food proteins
Authors: Hurrell R. F. , Carpenter K. J. 
Published: May 2005

1. A study has been made of pure proteins heated either alone or in contact with sugars, so as to cause a severe fall in their reactive lysine contents, and also of commercial protein concentrates.2. For unheated materials, and for bovine plasma albumin and fat-extracted, dried chicken muscle severely heated in the absence of sugar, Acid Orange 12 binding values (mmol bound dye/kg crude protein (nitrogen × 6·25)) were close to the sum of total histidine, total arginine and reactive lysine contents (mmol/kg crude protein (N × 6·25)), which we have termed HARL values. The dye-binding values and the HARL values were reduced similarly by heat treatment.3. For materials in which protein and glucose had reacted under mild conditions (37°), the dye-binding capacity with Acid Orange 12 was unchanged even though the HARL value of these materials was considerably reduced. When protein and glucose or sucrose were heated more severely, the dye-binding capacity was slightly lowered but not to the same extent as the reduction in the basic amino acids.4. Animal feeding-stuffs, whether unheated, industrially processed or deliberately heated, appeared to react with Acid Orange 12 in the same way as the model systems (selected to represent three types of heat damage: ‘advanced’ and ‘early’ Maillard and protein–protein damage).5. Remazol blue binding values and fluorodinitrobenzene (FDNB)-reactive lysine values were similarly reduced in materials that had been severely heated, either with or without added sugars; however, when protein and glucose had reacted under mild conditions the fall in Remazol blue binding was less than that in FDNB-reactive lysine.6. For the model materials, binding with cresol red was, in general, higher for heated samples but the results showed no correlation with FDNB-reactive lysine values. For meat and groundnut meals, changes in values after heat treatment were smaller than those that have been reported for soya-bean meals.
Anthropometric measurements and amounts of body fat and serum cholesterol in samples of three Nigerian populations
Authors: Watson R. S. , Etta K. M. 
Published: May 2005

1. Skinfold thicknesses, arm circumferences, heights, weights and serum cholesterol levels were determined in ninety-one university students, 207 soldiers and 102 out-patients, all male subjects. Some of these measurements were used to determine the amount of body fat, Quetelet's index and mid-arm muscle circumference2. Quetelet's indices and body-fat values obtained were similar to previously reported values for lean or moderately built males3. Serum cholesterol levels were generally low, with means ranging from 3·98 mmol/1 for 18- to 29-year-old students to 5·19 mmol/l for 40- to 69-year-old out-patients4. The mean values for triceps skinfold thickness, the amount of body fat and serum cholesterol levels for healthy adults obtained in this study are probably normal for northern Nigerian populations5. There was a significant correlation between the amount of body fat and values for triceps and subscapular skinfold thicknesses, Quetelet's index and body-weight for all adults. The correlation between muscle circumference and the amount of body fat was significant for all subjects except adult soldiers.
Concentrations of amino acids and urea in the plasma of the preruminant calf and estimation of the amino acid requirements
Authors: Williams A. P. , Smith R. H. 
Published: May 2005

1. A study was made of factors affecting the plasma concentrations of free amino acids (PAA) and urea (PU) in calves receiving liquid diets2. When calves were given whole milk (approximately 0·05 kg/kg live weight) at 10·00 and 17·00 hours there were marked decreases in PAA and slight decreases in PU for about 3–4 h after the morning feed. Both PAA and PU thereafter increased slightly and then remained constant for the next 10 h. In subsequent comparative experiments samples were taken 3 h after the morning feed. The variation in plasma methionine, isoleucine, leucine, phenylalanine, tyrosine and total PAA was apparently greater between than within animals3. In calves transferred from a diet of whole milk to one consisting of diluted whole milk supplemented with appropriate nutrients, including amino acids, but deficient in methionine, PU increased markedly and plasma methionine decreased4. Two calves (50–60 kg live weight) given the latter diet supplemented to give an intake of more than 4·5 g L-methionine/d together with 0·3 g cystine/d showed marked increases in plasma methionine. This was considered to correspond with the point at which methionine requirements were met and that under these conditions the methionine requirement for these calves (mean value ± SE) was 4·5 ± 0·2 g/d. In the same two calves PU decreased markedly with increasing levels of methionine supplementation up to 3·9 g/d and the estimated methionine requirement (mean value ± SE) was 3·9 ± 0·4 g/d.
The effect of pelleting on the voluntary intake and digestibility of leaf and stem fractions of three grasses
Authors: Laredo M. A. , Minson D. J. 
Published: May 2005

1. Leaf is eaten in greater quantities than stem of similar digestibility. To determine whether this difference is caused by physical or chemical factors, leaf and stem fractions from Digitaria decumbens, Chloris gayana and Setaria splendida were fed ad lib. to sheep in the chopped and pelleted forms. Pellets were made from leaf and stem which had been ground through a screen with 3 mm holes. All sheep received a protein and mineral supplement2. Voluntary intake of chopped leaf was 34% higher than that of the chopped stem fraction (40·3 and 30·0 g/kg body-weight0·75 respectively, P < 0·01) although dry matter digestibility ratios were similar (0·478 and 0·450 respectively, P > 0·05). The higher intake of leaf was associated with a larger surface area (13400 and 5200 mm2/g for chopped leaf and stem respectively), lower bulk density (60 and 180 kg/m3 respectively) and lower neutral-detergent fibre (706 and 724 g/kg respectively), acid-detergent fibre (383 and 413 g/kg respectively) and lignin (42 and 59 g/kg respectively) contents. Chopped leaf was retained in the reticulo-rumen for a shorter time than the stem fraction (19·9 and 26·4 h respectively)3. Grinding and pelleting increased the voluntary intake of the leaf fraction by 88% and the stem fraction by 60%. This increased voluntary intake caused by grinding and pelleting was not accompanied by any significant changes in the chemical composition of the diet. Grinding and pelleting reduced the time that the food was retained in the reticulo-rumen and this change appeared sufficient to account for the observed increases in voluntary intake4. It was concluded that the higher intake of the leaf fraction of grasses is caused by differences in retention time of food in the reticulo-rumen. These differences in retention time are caused by differences in physical properties and not chemical composition.
The subcellular localization of administered N-acetylneuraminic acid in the brains of well-fed and protein restricted rats
Authors: Morgan Brian L. G. , Winick Myron 
Published: May 2005

1. This study investigated the subcellular localization of injected N-acetylneuraminic acid (NeuNAc) in brain. Forty pregnant rats were distributed into four groups. Two groups were given a 200 g casein/kg diel and the other two groups a 100 g casein/kg diet throughout gestation. One group from each of the low- and high-protein groups were given their respective diets for the first 11 d of lactation. On day 12 of lactation, 2·5 μCi [14]NeuNAc/kg body-weight were injected intraperitoneally into their pups. After 1 h the pups were killed, their brains removed and subjected to subcellular fractionation. On day 16 of lactation the other two groups were similarly treated.2. In all groups of animals 80% of the [14C]NeuNAc incorporated into the brains was found in the synaptosomalfraction and the remainder distributed among the other subcellular fractions in proportion to their total NeuNA ccontent.3. These results suggest that NeuNAc exerts its effects on behaviour via the synaptic membrane.
A method to measure the water-holding properties of dietary fibre using suction pressure
Authors: Robertson J. A. , Eastwood M. A. 
Published: May 2005

1. Water-holding capacity (WHC) of dietary fibre is usually considered as the amount of water held but the manner in which water is held by the fibre matrix may be more relevant in understanding the role of fibre in nutrition.2. A method used to determine WHC under physiological conditions has been adapted to determine how strongly water is held by fibre. Solutions of compounds, such as polyethylene glycol, of known osmotic potential are used to generate a suction pressure across a dialysis membrane containing a fibre sample. The WHC at each suction pressure can then be determined.3. The method can be applied to water-soluble and water-insoluble sources of fibre. Fibre sources studied included potato fibre concentrate, bran and gum arabic.4. Results are comparable to other similar systems of WHC measurement for gels and suggest that vegetable fibre has water-holding properties more akin to a true gel than bran. Bran has very poor water-holding properties.5. Differences in WHC between fibre sources are more apparent if WHC is considered as fibre concentration (g fibre/g water).6. Differences in the water-holding properties could be important in determining fibre activity in the gut.
Riboflavin deficiency in man: effects on haemoglobin and reduced glutathione in erythrocytes of different ages
Authors: Powers Hilary J. , Thurnham D. I. 
Published: May 2005

1. Erythrocytes (RBC) from control and marginally riboflavin-deficient subjects were fractionated into nine fractions using a discrete density gradient.2. Glutathione reductase (NAD(P)H: glutathione oxidoreductase;EC1.6.4.2) activity and aspartate aminotransferase (EC2.6.1.1) activity (with and without the appropriate co-enzymes) reduced glutathione, methaemoglobin, sulphaemoglobin and oxyhaemoglobin and susceptibility to peroxide were measured in RBC in the different fractions.3. Glutathione reductase and aspartate aminotransferase activities and concentrations of reduced glutathione and oxyhaemoglobin all declined with age, while melhaemoglobin, sulphaemoglobin and susceptibility to peroxide increased with age.4. The only significant differences noted in the RBC from marginally-riboflavin-deficient subjects by comparison with controls, were lower glutathione reductase activities and higher concentrations of methaemoglobin.5. The role of riboflavin in those sytems controlling RBC integrity is discussed.
Guar bread: acceptability and efficacy combined. Studies on blood glucose, serum insulin and satiety in normal subjects
Authors: Ellis P. R. , Apling E. C. , Leeds A. R. , Bolster N. R. 
Published: May 2005

1. Bread alone and supplemented with guar gum at three levels (50, 100 and 150 g/kg) was given to eleven non-diabetic subjects, and blood glucose and serum insulin were determined preprandialy, and at 30 min and 60 min after commencement of the meal. The satiating effect, up to 120 min, of the guar bread and its acceptability to the same group of normal volunteers was also studied.2. No significant differences in blood glucose were observed between control and guar breads at 30 min and 60 min, apart from 100 g guar/kg bread at 30 min (P < 0·05). A significant difference in serum insulin was indicated between: control and 50 (P < 0·02) and 150 (P < 0·02) guar/kg breads at 30 min; control and 50 (P < 0·05), 100 (P < 0·001) and 150 (P < 0·05) guar/ke breads at 60 min.3. There were no significant differences in the satiety scores for control and guar breads. Significant increases in satiety attributed to 150 g guar/kg bread were found when compared to: 50 g guar/kg bread immediately after eating (P < 0·05), 100 g guar/kg bread at 60 min (P < 0·02) and 50 and 100 g guar/kg breads at 120min (both P < 0·05).4. There was a positive correlation between hedonic score and relative replacement of guar (r 0·62, P < 0·001, n 44) and from the regression line it was found that 50 and 100 g guar/kg breads produced hedonic scores close to a neutral response of 5, whereas 150 g guar/kg bread at a predictive score of 6·3 appeared to be unacceptable to our subjects.5. Guar bread at the 100 g/kg level (59 g guar/kg bread) reduced the serum insulin by 48% at 60 min and is found to be an acceptable food product at this level of incorporation. However, more information is required to demonstrate the possible satiating potential of guar bread.