bluuebunny/crossref_metadata_2025_split huggingface dataset:
The intestinal transport of zinc studied using brush-border-membrane vesicles from the piglet
Authors: Blakeborough Peter , Salter Dallyn N. 
Published: May 2005

1. Brush-border-membrane vesicles were prepared from piglet small intestines and the uptake of65Zn was studied using a rapid filtration assay. The mechanism of65Zn uptake was complex and two processes were identified.2. In the first process,65Zn uptake was rapid, reached equilibrium in 5–15 min and had an optimum pH of 7.5. The uptake was saturable and involved both binding to, and transport across, the membrane. The initial phase of65Zn uptake (1 min incubation) approached saturation at high levels of substrate65Zn and a Michaelis-Menten constant (Km) of 67.0 µM was calculated. Maximum uptake at equilibrium was approximately 100 nmol/mg protein. Cupric, ferrous and ferric ions had no effect on the uptake, but cadmium ions inhibited it competitively. The results are consistent with a carrier-mediated process, possibly involving a protein receptor in the membrane which is specific for Zn and elements close to it in the periodic table. Lactoferrin stimulated65Zn uptake by approximately 20% when pre-incubated with65Zn at a concentration of 0.01 µg/ml. It had no significant effect on65Zn uptake at higher concentrations or when pre-incubated with brush-border-membrane vesicles.3. The second mechanism of65Zn uptake was linear with respect to time and involved binding to the membrane only. It was inhibited by all divalent and trivalent metal ions tested and is probably a passive binding process.4. The results are discussed with respect to the use of brush-border-membrane vesicles in examining the role of nutrient interactions and their effect on the biological availability of nutrients.
The use of monensin or formaldehyde to control the digestion of the nitrogenous constituents of perennial ryegrass (Lolium perenne cv. Melle) and white clover (Trifolium repens cv. Blanca) in the rumen of cattle
Authors: Beever D. E. , Losada H. R. , Gale D. L. , Spooner M. C. , Dhanoa M. S. 
Published: May 2005

1. Pure swards of perennial ryegrass (Lolium perenne cv. Melle) and white clover (Trifolium repens cv. Blanca) were harvested daily as primary growth (grass in May, clover in June) or regrowths (clover only in July) and offered, in the long form, to growing cattle at a feeding rate of 22 g dry matter/kg live weight. With each forage, two treatments were compared with the untreated forage (C): monensin (100 g active ingredient/kg, 250 mg/d) addition to the rumen (treatment M) or formaldehyde (30 g/kg crude protein (nitrogen x 6.25)) application to the diet (treatment F). The objective of the experiment was to examine means of manipulating N metabolism in the rumen and the duodenal non-ammonia-N (NAN) supply derived from fresh forages.2. The apparent digestion of ingested organic matter (g/kg) in the rumen was unaffected by treatment M (C 509, M 497) but was significantly (P < 0.01) reduced by treatment F (443). The extent of cellulose digestion in the rumen was not affected by any of the treatments imposed and the changes in organic matter digestion were due mainly to effects on N digestion and rumen microbial synthesis. On the untreated diets, duodenal NAN supply averaged 0.74 g/g N intake and treatment M caused a small but non-significant increase (M 0.79 g/g N intake). In contrast, the effect of treatment F was much larger (F 0.91 g/g N intake; P < 0.01). These differences were accompanied by corresponding reductions in rumen NH3 concentrations (mg/l; C 350, M 310, F 220; P < 0.001).3. Of the increased flow of NAN to the small intestine observed on the white clover only diets with treatment F, 0.70 was accounted for by an increased net synthesis of microbial N, while treatment M had no effect on microbial N synthesis and a marginal reduction in feed N degradability only with the regrowth white clover diet. Treatment F reduced feed N degradability to a limited extent on both clover diets (C 0.82, M 0.81, F 0.77). No corresponding measurements were made for the ryegrass diets.4. It is concluded that the extensive loss of N from the reticulo-rumen of cattle fed on fresh forages can be reduced by the use of agents to reduce protein solubility. However, the study demonstrated that treatment F may in some circumstances increase N supply to the small intestine more through enhancing microbial N synthesis within the rumen than through increasing the passage of undegraded feed N to the small intestine. The use of monensin, to manipulate proteolytic or deaminative activity in the rumen, or both, was not found to confer any beneficial effects on duodenal-NAN supply.
Undernutrition in sheep. Nitrogen repletion by N-depleted sheep
Authors: Hovell F. D. DeB. , Ørskov E. R. , Kyle D. J. , MacLeod N. A. 
Published: May 2005

1. Wether lambs of 29–44 kg live-weight, totally nourished by the infusion of volatile fatty acids (VFA) into the rumen and casein into the abomasum, were given five treatments in consecutive periods. The treatments were (daily amounts per kg live weight (W)0.75): (a) high-protein for 7 d (2500 mg nitrogen, 650 kJ VFA); (b) low-protein for 7–15 d (525 mg N, 650 kJ VFA); (c) N-free for 7 d (no N, 450 kJ VFA); (d) very-low-protein for 24–28 d (300 mg N, 400 kJ VFA); (e) high-protein for 40 d (2500 mg N, 650 kJ VFA). Nine lambs were subjected to treatments (a), (b) and (c) (Expt 1) and four of the lambs additionally received treatments (d) and (e) (Expt 2).2. In Expt 1 all nine lambs had a positive N retention on treatment (a) but abrupt change to treatment (b) resulted in substantial negative N balances initially, and a period of approximately 5 d adaptation was required before N equilibrium was re-established. Animals again exhibited negative N balances when the N-free infusion (treatment c) was introduced and during that period there was no evidence of adaptation. Basal urinary N excretion was estimated to be 356 (SE 12) mg N/kg W0.75.3. In Expt 2 all four lambs were depleted of N when receiving the very-low-protein treatment (d). The progressively decreasing N losses recorded during days 1 to 12 of the treatment period were slightly greater than those recorded during days 13 to 28 but the difference between the means was not significant (P > 0.05). There was no evidence of an adaptation in N retention between days 13 and 28 of the treatment. As assessed during days 13 to 28 of the treatment the efficiency of utilization of infused casein N was 1.0; this compared with a value of 0.66 recorded during treatment (b) in Expt 1. Live weight loss during the period of N depletion was 101 (SE 27) g/d.4. When lambs were given treatment (e) during the last period of Expt 2, N repletion was rapid and complete within a few days. Ten days after the introduction of the treatment the rate of N retention was estimated to be 1019 (SE 38) mg/kg W0.75 per d and this value declined at a rate of 9.5 (SE 1.9) mg N/kg W0.76 per d for the following 30 d. In comparison, N retention determined for the high-protein treatment in Expt 1 was 724 (SE 66) mg N/kg W0.75 per d. Live-weight gains during N repletion were 292 (SE 26) g/d.5. It is concluded that N-depleted lambs can replete rapidly and that enhanced N accretion (compensatory growth) may persist for 4–5 weeks. If the improved efficiency of utilization of infused N observed during N depletion reflects a changed basal N requirement, the validity of simple factorial systems for estimating N requirement is called into question.
The effect of the β-2-adrenergic agonist clenbuterol or implantation with oestradiol plus trenbolone acetate on protein metabolism in wether lambs
Authors: Bohorov O. , Buttery P. J. , Correia J. H. R. D. , Soar J. B. 
Published: May 2005

1. The effects of Revalor (trenbolone acetate plus oestradiol) implantation or the inclusion of clenbuterol (a β-2-adrenergic agonist) in the diet of wether lambs was studied. Using continuous intravenous infusion of [3H]tyrosine the fractional synthetic rate of mixed protein from three separate muscles was measured.2. Clenbuterol slightly increased growth rate but had a significant (P< 0.02) effect on food conversion efficiency. The weight and protein content of the longissimus dorsi and vastus lateralis muscles were increased but no such changes were observed for the vastus intermedius. For the longissirnus dorsi at least the increase was probably achieved by a reduction in fractional degradation rate of the muscle protein.3. Revalor significantly increased the growth rate and food conversion efficiency of the animals. This increase was not specific for muscle. Estimated degradation rates of muscle protein were lower in the treated animals.4. The possible mode of action of these materials was discussed. The results obtained again highlight the importance of protein degradation in controlling growth.
Influence of rumen ammonia concentration on the rumen degradation rates of barley and maize
Authors: Odle J. , Schaefer D.M. 
Published: May 2005

1. Four rumen-cannulated steers were given barley and maize diets supplemented with graded levels of an ammonium acetate solution.2. Animals were fed hourly from automatic feeders and water consumption was controlled to achieve steady-state conditions in the rumen.3. Dacron bags containing rolled barley or ground barley were incubated in the rumen of barley-fed steers, while ground maize and autoclaved maize were incubated in the rumen of maize-fed steers.4. Fractional degradation rates of dry matter were estimated for each cereal substrate incubated using a single-pool exponential decay model.5. No differences in degradation rate due to the method of feed processing were detected; however, barley was degraded at a faster rate than maize. Furthermore, the minimum rumen ammonia-nitrogen concentration required to maximize the degradation rate of barley (125 mg/l) was greater than that required to maximize the degradation rate of maize (61 mg/l).6. These results indicate that the optimal NH3-N concentration required to maximize the rate of grain digestion in the rumen is influenced by the chemical or structural characteristics of the grain.
The effects of severe zinc deficiency on protein turnover in muscle and thymus
Authors: Giugliano R. , Millward D.J. 
Published: May 2005

1. Measurements have been made of protein turnover, RNA and DNA in thymus and skeletal muscle from rats fed on a zinc-deficient diet (ZD) for 10 and 17 d, in pair-fed controls (CI) and in muscle from rats fed on the ZD diet for 24 d and then fed on restricted amounts of the deficient diet with (RIZS) or without (RIZD) Zn supplementation, for 8 d.2. In thymus the ZD diet induced a loss of DNA and protein which was not observed with the CI rats. Accumulation of RNA was less affected but protein synthesis was reduced.3. In muscle the accumulation of DNA and protein was slowed by the ZD diet, particularly in glycolytic muscles compared with oxidative muscles, and Zn supplementation increased DNA and protein.4. Protein synthesis and RNA concentrations were reduced in the ZD rats compared with the CI rats, but Zn supplementation at constant restricted food intake did not increase protein synthesis. Muscle protein synthesis per unit RNA varied markedly in the ZD rats after 10 d when the characteristic cycling of the food intakes and body-weight was most pronounced, the highest values being observed in the anabolic phase of the cycle although these were less than values for well-fed controls. The variability was inversely correlated with the plasma Zn levels. The extent of the variability was much less after 17 d and was not apparent in the food-restricted ZD animals.5. Protein degradation in muscle, assessed as the difference between overall and net protein synthesis, was faster in the ZD rats compared with the CI rats and fluctuated considerably, partly accounting for the cyclic changes in muscle after 10 d, and was entirely responsible after 17 d. The concentration of muscle-free 3-methylhistidine and its urinary excretion rate indicated inconsistent results which could not be satisfactorily interpreted.6. Plasma insulin was reduced in the ZD rats compared with the CI rats and was insensitive to food intake in contrast to urinary corticosterone excretion which was inversely correlated with the cyclic changes in body-weight and food intake. Furthermore, adrenalectomized rats exhibited increased mortality and reduced cycling of body-weight and food intake.7. Thus Zn deficiency impairs growth by a combination of (a) reduced food intake, (b) a reduced anabolic response to food due to a reduced capacity for protein synthesis and reduced activation of protein synthesis, possibly reflecting impaired insulin secretion, and (c) an increased catabolic response to the reduced intake in which corticosterone may play a role.
Raw soya-bean flour increases cholecystokinin release in man
Authors: Calam John , Bojarski Joanna C. , Springer Caroline J. 
Published: May 2005

1. The aim of the present study was to determine whether oral ingestion of raw soya-bean flour, which contains trypsin inhibitors, alters the release of cholecystokinin (CCK) in man.2. Eleven healthy volunteers ate two mixed meals: one with raw soya-bean flour and the other with soya-bean flour that had been heat-treated. The two flours inhibited 34 and 3 mg trypsin/g flour respectively.3. CCK was measured in plasma using a bioassay based on the release of amylase (EC 3.2.1.1) from dispersed rat pancreatic acini.4. The peak CCK response was 168 (SE 8.1) pmol/l with raw soya-bean flour but 4.9 (SE 2.8) pmol/l with heat-treated flour (P < 0.05).5. We conclude that ingestion of raw soya-bean flour increases CCK release in man and that heat treatment which reduces the trypsin inhibitor content of the flour also diminishes its CCK-releasing effect.
Liver stores of vitamin A in human fetuses in relation to gestational age, fetal size and maternal nutritional status
Authors: Shah Raksha S. , Rajalakshmi R. , Bhatt R. V. , Hazra M. N. , Patel B. C. , Swamy N. B. , Patel T. V. 
Published: May 2005

1. Studies were made on liver stores of retinol in aborted human fetuses and stillborn babies in relation to gestational age, fetal size and maternal retinol status. The mothers belonged to low-and high-income groups (LIG and HIG respectively) in urban Baroda.2. Fetal weights were less than those reported by Widdowson (1968) for similar gestational ages and the deficits were greater in LIG.3. The combined mean values (μg/l) for maternal serum retinol for all gestational ages were 193 for LIG and 261 for HIG. They were found to decline in late pregnancy in the former but not significantly in the latter.4. Fetal liver retinol concentrations were much lower than those reported for healthy Thai subjects by Montreewasuwat & Olson (1979) in early pregnancy but showed complete ‘catch up’ in late pregnancy for HIG and to a considerable extent for LIG.5. Significant correlations were found between maternal serum retinol, fetal liver retinol and fetal growth.6. These findings stress the importance of adequate vitamin A supplies during pregnancy to prevent vitamin A deficiency and intra-uterine growth retardation in the newborn.
Vitamin E status of the newborn in relation to gestational age, birth weight and maternal vitamin E status
Authors: Shan Raksha S. , Rajalakshmi R. , Bhatt R. V. , Hazra M. N. , Patel B. C. , Swamy N. B. , Patel T. V. 
Published: May 2005

1. Studies were made on the vitamin E status of the newborn as judged by cord serum vitamin E and erythrocyte haemolysis in vitro in relation to gestational age, birth weight and maternal vitamin E status in subjects belonging to low (LIG)- and high (HIG)-income groups in urban Baroda.2. In the case of full-term infants, the mean values for maternal serum vitamin E (mg/l) for LIG (n 73) and HIG (n 43) were 9.9 (SE 0.4) and 11.6 (SE 0.5). The corresponding values for cord serum vitamin E were 3.6 (SE 0.2) and 4.6 (SE 0.2) mg/l.3. Serum vitamin E levels (mg/l) were lower in premature infants (2.3 (SE 0.2); n 20) and low-birth-weight full- term infants (2.9 (SE 0.2); n 25) than in full-term normal infants (4.2 (SE 0.1); n 91). This was associated with differences in maternal serum vitamin E levels (7.4 (SE 05), 8.2 (SE 0.5) and 11.1 (SE 0.3) respectively). The differences were more marked for LIG.4. A negative correlation was found between serum vitamin E and erythrocyte haemolysis in vitro in the case of maternal blood but not in cord blood.5. These results suggest that maternal vitamin E deficiency is one of the features associated with prematurity and intra-uterine growth retardation.
Hydrolysis of lactitol, maltitol and Palatinit® by human intestinal biopsies
Authors: Nilsson U. , Jägerstad M. 
Published: May 2005

1. The hydrolysis of sugar alcohols of the disaccharide type such as lactitol, maltitol and Palatinit® (the latter an equimolar mixture of 6-O-α-D-glucopyranoside-D-mannitol and 6-O-α-D-glucopyranoside-D-sorbitol) by homogenates of human intestinal biopsies were compared with corresponding natural disaccharides such as lactose, maltose and isomaltose. Seven of the human biopsies were normal with regard to their disaccharidase activities, while twelve biopsies showed decreased levels of disaccharidase activities.2. All biopsies, normal as well as abnormal, showed essentially the same capacity to hydrolyse the sugar alcohols. Activities towards lactitol (0.34 IE/g protein (where IE = μmol disaccharide hydrolysed/min at 37°)) and Palatinit (2.50 IE/g protein) were only 1.3% of those towards lactose and isomaltose. The activity towards maltitol was much higher (19.1 IE/g protein), approximately 10% of that towards maltose and about as high as the activity towards trehalose. This finding indicates that despite the fact that lactitol and Palatinit were poor substrates, significant amounts of ingested maltitol might be digested and utilized by man.3. Glucose release was reduced by approximately 25% when maltitol or Palatinit were present at concentrations equal to those of maltose. Palatinit decreased the hydrolysis of sucrose by 12%. Lactitol had no inhibitory effect on the hydrolysis of disaccharides.
Urinary excretion of 5-oxoproline (pyroglutamic aciduria) as an index of glycine insufficiency in normal man
Authors: Jackson Alana A. , Badaloo A. V. , Forrester T. , Hibbert J. M. , Persaud C. 
Published: May 2005

1. The evidence is accumulating to suggest that glycine, the simplest amino acid, is conditionally essential in man. Benzoic acid, by conjugation with glycine to form hippuric acid, is known to deplete the free glycine pool of the body. Glycine is one substrate for the enzyme glutathione synthase (EC 6.3.2.3) and in the inborn error of metabolism in which glutathione synthase function is defective, increased quantities of 5-oxoproline are excreted in the urine.2. An oral dose of 4–10 g sodium benzoate was given to six normal adults to deplete the metabolic pool of glycine, and the urinary excretion of 5-oxoproline was followed for 6 h. In five of the six, a significant increase in the urinary 5-oxoproline was seen within 3 h.3. These-findings show that 5-oxoprolinuria can result from limited glycine availability, and may provide a useful test for assessing glycine sufficiency in a range of physiological and pathological states.
Gestational protein–energy malnutrition affects the composition of developing skins of rat fetuses and their dams
Authors: Miwa Takashi , Shoji Hiromu , Solomonow Moshe , Yazdani Malektaj , Nakamoto Tetsuo 
Published: May 2005

1. Various biochemical variables of the skins of rat dams and their fetuses in which protein-energy malnutrition was induced during pregnancy were analysed.2. One group of dams was fed on a 200 g protein/kg diet as a control and the other was fed on a 60 g protein/kg diet as an experimental group. Each group of dams was fed from day 13 of gestation until day 22.3. Water, protein and hexosamine concentrations of the fetal skins in the malnourished group were greater than those in the control group, whereas in the dams′ skins, protein concentration was greater in the malnourished group than in the control group.4. Extractability of collagen with neutral salt and pepsin showed no difference between the groups in the skins of fetuses and dams. The content of type III collagen in the fetal skin did not differ between the groups, but was increased in the malnourished dams′ skins compared with that of the control group.5. The present study showed that protein-energy malnutrition during pregnancy significantly affects the metabolism of the skin in both fetuses and their dams. Furthermore, the skins of fetuses and dams are structurally altered in different ways by this nutritional stress.
Dietary fat and N-nitrosation in the rat
Authors: Ward F. W. , Coates M. E. 
Published: May 2005

1. Groups of four conventional (CV) rats ate natural or purified diets either with or without 100 g fat/kg and drank 0.235 M-sodium nitrate. The fats tested were butterfat, coconut oil, olive oil, maize oil and safflower oil.2. Decreased urinary excretion of N-nitrosoproline (NPRO) was observed in rats fed on fat-supplemented diets compared with those fed on low-fat diets, with butterfat having the greatest effect of the fats tested.3. Reduced excretion of NPRO was not the result of inhibition of the intragastric N-nitrosation reaction or absorption of nitrosamine from the gastrointestinal tract.4. The availability of nitrite in aqueous solution was decreased by the fat diets but the effect was similar in all the fats tested.5. Nitrate reductase activity was present in the forestomach contents of CV rats at pH > 4 and was apparently inhibited by feeding a fat diet. No nitrate reductase activity was detected in stomach contents of germ-free rats.6. Nitrate reductase activity in stomach and small intestinal tissue was not altered by feeding a fat diet.7. It was concluded that nitrate reductase activity in stomach contents was of microbial origin and the decreased urinary excretion of NPRO on feeding the fat diets was mainly due to the inhibition of nitrate reductase activity in stomach contents.
Effect of human faecal inoculum on in vitro fermentation variables
Authors: McBurney M. I. , Thompson L. U. 
Published: May 2005

1. Homogenized and diluted faeces (66.6 g/l) collected from one human source on three different months was incubated with four standard substrates (oat bran, wheat bran, red kidney beans (Phuseolus vulgaris) and guar gum) for 4, 8, 12 and 24 h.2. Neutral-detergent fibre and organic matter (OM) digestibility measurements and gas production (ml gas/g OM) were influenced by substrate and incubation period but not by day of collection.3. Production of short-chain fatty acids (SCFA) (mmol/g OM) was a function of substrate and incubation period but not day of collection at 4, 8 and 12 h. Rapidly fermentable substrates such as red kidney beans and guar gum did not ferment beyond 12 h and SCFA values were not different at 24 h.4. Substrates differed in amount, rate and type of SCFA produced.5. The results indicate that human faeces collected on different occasions were sufficiently uniform to yield similar in vitro fermentation findings among collections. Therefore, it is concluded that human faecal material is a practical source of micro-organisms to evaluate the fermentation properties of substrates.