bluuebunny/crossref_metadata_2025 huggingface dataset:
Involvement of the solid phase of rumen digesta in the interaction between copper, molybdenum and sulphur in sheep
Authors: Allen J. D. , Gawthornet J. M.
Published: May 2005

1. Merino sheep fed on a diet of chopped wheaten hay, chopped lucerne (Medicago saliva) hay and oat grain were the source of rumen contents for the study. The diet contained (mg/kg dry weight) 3.3 copper, 0.24 molybdenum and 2.8 sulphur. The effects of adding between 5 and 25 mg Mo/kg as ammonium molybdate (AM) or tetrathiomolybdate (TTM) on the distribution and forms of Cu and Mo in rumen contents were investigated in vivo and in vitro.

2. Approximately 88 % of the Cu and 94% of the Mo in rumen contents were associated with the solid phase. When AM or TTM was added to rumen contents in vivo or in vitro the proportion of these elements in the solid phase was increased at the expense of the fluid phase.

3. The addition of AM and TTM to rumen contents also decreased the proportion of Cu that was soluble in trichloroacetic acid (50 g/l; TCA) and increased the proportion of Cu that was not extractable by sequential treatment with TCA and neutral detergent.

4. Column chromatography of neutral-detergent extracts of rumen contents revealed that TTM treatment caused Cu to be strongly bound to proteins of high molecular weight.

5. Addition of sulphide to rumen contents did not result in significant changes in the distribution of Cu between the fluid and solid phases, or in the solubility of Cu in TCA.

6. It is postulated that constant removal of TTM from the fluid phase via reaction with proteins and other macromolecules in the solid phase results in greater formation of TTM in vivo than would be expected from solution chemistry. The molybdo-proteins so formed are strong chelators of Cu and may be the agents responsible for the decrease in Cu absorption in animals that consume diets containing high concentrations of Mo.
Effects of the amount and quality of dietary protein on nitrogen metabolism and heat production in growing pigs
Authors: Fuller M. F. , Cadenhead A. , Mollison G. , Seve B.
Published: May 2005

1. Eight pigs with a mean weight of 48 kg were given, at a constant daily rate, diets of low (0.15) or high (0.30) protein content, very deficient in lysine, with or without a supplement of L-lysine (3.7 g/kg).

2. Measurements of nitrogen and energy metabolism were made in four successive 14 d periods in a Latin-square design.

3. The rate of protein accretion was substantially increased by increases in both protein and lysine supply, but the rate of heat production was not significantly changed.

4. The rate of fat deposition varied inversely with the rate of protein accretion, being reduced by both protein and lysine supplements.

5. The relation between heat production and protein accretion (allowing for a constant energy cost of fat deposition) suggested that heat production increased with additional protein accretion less when protein quality was improved than when more protein was given.
Effects of the amount and quality of dietary protein on nitrogen metabolism and protein turnover of pigs
Authors: Fuller M. F. , Reeds P. J. , Cadenhead A. , Seve B. , Preston T.
Published: May 2005

1. The interrelations between protein accretion and whole-body protein turnover were studied by varying the quantity and quality of protein given to growing pigs.

2. Diets with 150 or 290g lysine-deficient protein/kg were given in hourly meals, with or without lysine supplementation, to female pigs (mean weight 47 kg).

3. After the animals were adapted to the diets, a constant infusion of [14C]urea was given intra-arterially for 30 h, during the last 6 h of which an infusion of [4,5-3H] leucine was also infused at a constant rate. At the same time, yeast-protein labelled with15N was given in the diet for 50 h.

4. The rate of urea synthesis was estimated from the specific radioactivity (SR) of plasma urea. The rate of leucine flux was estimated from the SR of plasma leucine. The irrevocable breakdown of leucine was estimated from the3H-labelling of body water. Total N flux was estimated from the16N-labelling of urinary urea.

5. Addition of lysine to the low-protein diet significantly increased N retention, with a substantial reduction in leucine breakdown, but there was no significant change in the flux of leucine or of total N.

6. Increasing the quantity of the unsupplemented protein also increased N retention significantly, with concomitant increases in leucine breakdown and in the fluxes of leucine and of total N.

7. It is concluded that a doubling of protein accretion brought about by the improvement of dietary protein quality is not necessarily associated with an increased rate of whole-body protein turnover.
Urea synthesis and leucine turnover in growing pigs: changes during 2 d following the addition of carbohydrate or fat to the diet
Authors: Reeds P. J. , Fuller M. F. , Cadenhead A. , Hay S. M.
Published: May 2005

1. Studies have been made of the time-sequence of protein metabolic and hormonal changes following an abrupt increase in carbohydrate or fat intake. [3H]leucine and [14C]urea were infused for 72 h, via the aorta, into fourteen female pigs (30–38 kg body-weight). At 24 h after the start of the infusion their feed was either changed to one of two isonitrogenous diets containing additional starch (group BS, five animals) or fat (group BF, five animals), or remained unaltered (group BB, four animals). The distribution space of urea was measured by the dilution of a single dose of [14C]urea given both 48 h before and 48 h after the change in diet. The changes in the concentration and specific radioactivity of blood leucine were used to infer changes in protein turnover and those of plasma urea to measure total amino acid catabolism. The concentrations of blood glucose and plasma insulin and cortisol were also measured at approximately two-hourly intervals for the 48 h period following the change in diet.

2. Within 4 h of either change in diet blood leucine concentration was lowered and the leucine specific radioactivity was raised above that in group BB, but after 24 h both the concentration and specific radioactivity of leucine returned to values similar to those in group BB. Eventually the blood leucine specific radioactivity was slightly but not significantly reduced below that of group BB.

3. The addition of starch to the diet significantly reduced the synthesis and concentration of urea within 4 h but, although the addition of fat to the diet eventually lowered the urea concentration and synthesis, both changes were delayed for 18–24 h.

4. In group BS plasma glucose and insulin rose after the addition of starch, but after 24–36 h both returned to values that were the same as those in the animals that received the same diet throughout (group BB). The addition of fat to the diet altered neither blood glucose nor plasma insulin concentrations. The addition of either carbohydrate or fat to the diet eventually reduced pIasma cortisol concentrations, but the change did not occur until 24 h after the change in diet.

5. The results suggest that alterations in non-protein energy supply exert their immediate effect on the degradation of whole-body protein. They do not exclude the possibility that these early changes may reflect opposing changes at different sites. The results also suggest that the rate of urea synthesis may be controlled by the balance between the concentrations of insulin and cortisol, but that under the conditions of these experiments there was little relation between these hormones and the turnover of body protein as measured by the turnover of blood leucine.
Factors affecting the rate of breakdown of bacterial protein in rumen fluid
Authors: Wallace R. J. , McPherson Carol A.
Published: May 2005

1. The cellular proteins ofButyrivibrio jibrisolvens, Lactobacillus casei, Megasphaera elsdenii, Selenomonas ruminantiumandStreptococcus boviswere labelled by growth in the presence of L-[14C]leucine, and the breakdown of labelled protein was measured in incubations of these bacteria with rumen fluid to which unlabelled 5 mM-L-leucine was added. The rate of protein breakdown was estimated from the rate of release of radioactivity into acid-soluble material.

2. Protein breakdown occurred at different rates in different species. The mean rates for B.fibrisolvens, L. casei, M. elsdenii, Sel. ruminantiumandStr. boviswere 28.6, 18.1, 17.7, 10.5 and 5.3% /h respectively in samples of strained rumen fluid (SRF) with different protozoal populations. Rates of 3% /h or less were found in SRF from ciliate-free sheep or in faunated SRF from which protozoa had been removed by centrifugation. Further removal of mixed rumen bacteria had little effect. Suspensions of washed protozoa degraded bacterial protein at rates which were of the same order as those found in SRF.

3. The rate of breakdown of bacterial protein in different samples of SRF tended to increase as the numbers of small entodiniomorphid protozoa increased. The numbers of larger entodiniomorphs and holotrichs had no obvious influence on this rate.

4. Autoclaved and u.v.-treated bacteria were generally no different from live bacteria in their susceptibility to breakdown in SRF from faunated sheep, indicating that endogenous protein turnover was not a significant cause of bacterial protein catabolism.

5. The rate of bacterial protein breakdown was unrelated to the proteolytic activity of SRF.

6. It was concluded that predation by small protozoa is by far the most important cause of bacterial protein turnover in the rumen, with autolysis, other lytic factors and endogenous proteolysis being of minor importance.
Effects of infusions of lysine, leucine and ammonium chloride into the hepatic portal vein of chickens on voluntary food intake
Authors: Rusby Audrey A. , Forbes J. M.
Published: May 2005

1. Adolescent cockerels of a laying strain were prepared with catheters whose tip lay in the hepatic portal vein, to study the effect of 3-h infusions of nutrients on food intake.

2. Lysine, infused into the hepatic portal vein at rates of 150–450 mg/3 h reduced 3-h food intake by up to 58%, for a period of 6 h in previously starved birds, but had no effect on birds allowed free access to food. Infusions made into the jugular vein had no effect, suggesting a role for the liver in monitoring lysine levels.

3. Portal infusion of leucine had a delayed effect while ammonium chloride, infused at isomolar rates to those of the lysine infusions, had very little effect on intake.

4. The results support the concept of liver sensitivity to amino acids, but the mode of action is not clear; it appears not to be via the effects of ammonia.
Nutrient composition is a poor determinant of the glycaemic response
Authors: Sud Sudha , Sud Sudha
Published: May 2005

1. The glycaemic response of healthy males to potato, bread, rice and green gram (Phaseoh aureus Roxb.) was compared with that to meals equivalent to these foods in terms of carbohydrate, protein, fat and fibre content, but made up of maize flour, casein, maize oil and ispaghula husk.

2. Natural foods led to a higher postprandial glycaemia than their respective equivalents, but the difference was significant only in the case of potato at 0.5 h (P < 0.05).

3. The insulin response, studied only in the case of rice and green gram, followed a trend similar to the glycaemic response but the differences between natural foods and equivalents were even more marked.

4. A food is more than the sum of its major nutrients. Several poorly understood factors may contribute to the glycaemic response to a food. In addition to the quantity of nutrients, the response may be the result of the specific type of nutrients, non-nutrient chemicals and anti-nutrients composing the food, and their unique physical arrangement within the food.
Selenium (selenate) transport by human placental brush border membrane vesicles
Authors: Shennan D. B.
Published: May 2005

1. Selenate uptake by human placental brush-border-membrane vesicles was studied in order to establish whether this anion shares a pathway with sulphate.

2. Selenate uptake was found to be saturable with respect to medium selenate and was inhibited by the anion exchange inhibitor 4,4′-diisothiocyano-stilbene-2,2′-disulphonate (DIDS).

3. Anions which have a similar tetrahedral shape to selenate, e.g. chromate, molybdate, tungstate and sulphate, were effective inhibitors of selenate uptake when added to the incubation medium.

4. Sulphate inhibited selenate influx in a dose-dependent fashion; moreover sulphate was found to be a competitive inhibitor of selenate uptake.

5. It is concluded that selenate and sulphate share a pathway for transport in the human placental microvillus membrane.
A viscous fibre (methylcellulose) lowers blood glucose and plasma triacylglycerols and increases liver glycogen independently of volatile fatty acid production in the rat
Authors: Topping David L. , Oakenfull David , Trimble Rodney P. , Illman Richard J.
Published: May 2005

1. Adult male rats were maintained on diets containing 80 g methylcellulose/kg of low (25 cP), medium (400 cP) and high (1500 cP) viscosity.

2. After 10 d, the viscosity of stomach and caecal contents was found to have increased in proportion to that of the dietary fibre. Concentrations of volatile fatty acids in caecal digesta were lowest with the high-viscosity fibre but acetate was the major acid present with all three diets. Acetate was the only acid found in significant quantities in hepatic portal venous plasma and concentrations of this acid were unaffected by diet.

3. Concentrations of glucose in arterial blood were low with the medium-and high-viscosity diets while the content of liver glycogen was high. These effects of fibre were not directly on glucose absorption as the intestines were net removers of the hexose at the time of sampling.

4. Hepatic lipogenesis and plasma triacylglycerol concentrations were both higher in rats fed on the low-viscosity fibre. Plasma cholesterol concentrations, hepatic cholesterol synthesis and faecal bile acid excretion were not altered by dietary fibre viscosity.

5. We conclude that the effects of dietary fibre on carbohydrate absorption and storage and fatty acid synthesis are a function of the viscosity of the fibre in solution, high viscosity slowing the digestion and absorption of nutrients in the small intestine. Large-bowel microbial fermentation is not of direct significance to these events. In contrast, effects of fibre polysaccharides on sterol metabolism seem not to be related to their rheological properties.
Effect of cooking, pH and polyphenol level on carbohydrate composition and nutritional quality of a sorghum (Sorghum bicolor (L.) Moench) food, ugali
Authors: Knudsen K. E. Bach , Munck L. , Eggum B. O.
Published: May 2005

1. The present work was undertaken to study the effects of cooking, pH and polyphenol level on carbohydrate composition and nutritional quality of sorghum (Sorghum bicolor (L.) Moench). Three different sorghum varieties; Dabar, Feterita and Argentine containing zero, intermediate to low and high levels of polyphenols respectively were used in the study. From these varieties uncooked, uncooked acidified, cooked, and cooked acidified diets were prepared. Diets were characterized with regard to resistant starch (RS), dietary fibre (DF), acid-detergent fibre (ADF) and amino acid content. Raw materials were further analysed for content and composition of non-starch polysaccharides and Klason lignin. The nutritional properties were studied in balance trials with rats. True protein digestibility (TD), biological value (BV), net protein utilization, digestible amino acids, digestible energy (DE) and digestible DF were used as criteria in the nutritional study.

2. Cooking at neutral and acid pH resulted in significantly higher assayed values for DF. Increase in DF could be accounted for by formation of RS. Approximately 50% of RS was recovered in the faeces.

3. In vitro values for protein associated with ADF and in vivo balance values using rats suggest that an endosperm protein fraction, kafirins, was made unavailable during cooking. This resulted in reduced TD and increased BV. It is assumed that unavailable kafirins serve as a nitrogen source for microflora in the hind-gut.

4. Dietary polyphenols changed the excretory route for N from urine to faeces. This resulted in lower TD and higher BV in Argentine (high in polyphenols) than in Dabar and Feterita (low in polyphenols), although dietary lysine (first limiting amino acid) was the same in the three varieties.

5. Variation in DE of the diets was attributed to DF, RS and the amount of faecal protein, which in turn were influenced by undigested kafirins and polyphenols.
The effect of Gypsophila saponins in the diet on mineral status and plasma cholesterol concentration in the rat
Authors: Southon Susan , Johnson I. T. , Gee Jennifer M. , Price K. R.
Published: May 2005

1. Immature, male Wistar rats were allocated to one of six groups and caged individually. The first group was given a semi-synthetic diet containing 38 mg iron and 55 mg zinc/kg (basal group). The second and third groups were given a diet containing 10 mg Zn and 12 mg Fe/kg respectively (low-Zn and low-Fe groups). Groups four, five and six were given similar diets containing 20 gGypsophilasaponins/kg. After 21 d the Fe and Zn status of the rats was estimated and plasma cholesterol concentration determined.

2. Measurements of whole blood haemoglobin concentration, packed cell volume and liver Fe stores indicated that rats in the basal + saponin and low-Fe + saponin groups had a significantly reduced Fe status when compared with their controls. Rats in the low-Zn + saponin group also showed a trend toward reduced Fe stores.

3. Zn status, as judged by femur Zn concentration, was not adversely affected by the inclusion ofGypsophilasaponins in the diet.

4. Consumption of the saponins resulted in a significant reduction in blood cholesterol concentration, with rats in both the low-Fe groups having significantly lower concentrations than their basal and low-Zn counterparts.

5. In view of suggestions that the consumption of saponins should be encouraged because of their ability to lower blood cholesterol, possible effects on Fe metabolism should be investigated further, particularly with respect to the levels and sources of saponin in the human diet.
Factors affecting the voluntary intake of food by sheep
Authors: Grovum W. L. , Chapman H. W.
Published: May 2005

1. Sheep with oesophageal fistulas were sham-fed on pelleted lucerne (Medicago sativa) hay to assess the palatability of added chemicals representing the tastes of sweet (sucrose), sour (hydrochloric acid), salt (sodium chloride), bitter (urea) and umami (monosodium glutamate; MSG).

2. Plain pellets and four concentrations of each chemical were sham-fed for 30 min after 5·5 h deprivation in 5x5 Latin-square experiments following a period of adaptation feeding.

3. Sucrose, at concentrations of 15–120 g/kg air-dried pellets, depressed intakes with a linear relation between intake (I; g) and concentration (C; g/kg): I = 1001-3·42C.

4. HCl at 6·25–25·0 g/kg pellets had no effect on sham intakes but at 50 g/kg reduced them by 50% of control (P < 0·05).

5. NaCl at 50–200 g/kg increased sham intakes by 26% (P < 0·01) with no evidence of a dose-related effect.

6. Urea at 10–80 g/kg decreased sham intakes by 26·9% (P < 0·01) with no evidence of a dose-related effect.

7. MSG at 5–40 g/kg in two experiments increased sham intakes by 16·1 and 40·8% (P < 0·05). In another experiment at 1-8 g/kg there wasno significant effect.

8. When palatability and post-ingestive effects are separated by sham-feeding, the effect of added chemicals on intake may be completely different from when they are ingestednormally (e.g. NaCl and sucrose). This newly developed technique enables the palatabilityeffect of feed additives to be tested critically and economically.
Messenger RNA levels of plasma proteins following fasting
Authors: De Jong Felice A. , Howlett Geoffrey J. , Schreiber Gerhard
Published: May 2005

1. The effect of fasting on hepatic mRNA levels of seven plasma proteins was examined in the rat.

2. The levels of mRNA were measured directly in cytoplasmic extracts by hybridization to specific32P-labelled cDNA probes.

3. Following a 48 h period of fasting, the mRNA levels of apolipoprotein E, apolipoprotein A-IV, albumin, transferrin, and transthyretin decreased by 15–30%, while apolipoprotein A-II decreased by 78% compared with non-fasted control rats. The mRNA for apolipoprotein A-I increased by 33%.

4. These findings suggest that mRNA levels in the liver following fasting are regulated independently and variations in these levels may be due to differences in transcription rates or mRNA stability.
Influence of lactose on phosphate metabolism in rats
Authors: Dębiec Hanna , Lorenc Roman
Published: May 2005

1. Lactose, sucrose or maltose were administered to rats by gavage together with32PO4, and blood32P was determined.

2. PO4uptake into blood was increased only when lactose and PO4were administered into the gut.

3. Weaned male rats were fed on a control diet or a diet containing 30, 60 or 120 g lactose/kg. After a 5 d period of adaptation, a 6 d P balance was carried out. After a further 24 d blood levels of PO4, and calcium and PO4uptake by brush-border membrane vesicles prepared from the renal cortex, were determined.

4. The absorption and retention of P were higher in lactose-fed rats. Faecal P excretion decreased with increasing dietary lactose content. Urinary P excretion was lower in the rats fed on 30 and 60 g lactose/kg whereas the 120 g lactose/kg diet increased urinary P.

5. Membrane vesicles isolated from rats fed on the diets containing 30 and 60 g lactose/kg showed a higher uptake of PO4, but with the 120 g lactose/kg diet uptake was lower than with membrane vesicles isolated from rats fed on the control diet.

6. A statistically significant increase in the serum PO4level was observed in the rats fed on the diet with 120 g lactose/kg.

7. The presence of lactose in the diet caused a stirnulatory effect on PO4absorption and retention.
The prediction of body composition in poultry by estimation in vivo of total body water with tritiated water and deuterium oxide
Authors: Johnson R. J. , Farrell D. J.
Published: May 2005

1. Birds (n169) which varied in age, live weight, nutritional history, physiological state and genotype were slaughtered and analysed for total body water. Before slaughter, birds were injected with the water isotopes tritiated water (TOH) or deuterium oxide (D2O), or both, to determine TOH space or D2O space, or both, as estimates of total body water in vivo.

2. At the mean total body water of all birds determined by desiccation, of 1096·4 (SD 424·1) g, TOH space and D2O space overestimated total body water by 10·4 and 8·5 % respectively. The difference between the isotopes was significant (P< 0·05).

3. Based on recovery of isotope it was postulated that the main reason for the observed overestimation of total body water in vivo was incomplete recovery of isotope due to the vacuum sublimation technique. The mean recovery (%) of added isotope to whole blood after vacuum sublimation was 93·0 (SD 2·6) and 92·4 (SD 5·5) of the theoretical concentrations of TOH and D2O respectively.

4. Nevertheless, accurate prediction of total body water was obtained from regression equations which included live weight and isotope-dilution space. Values required logarithmic (base 10) transformation before derivation of linear and multiple linear regression equations, and the precision of prediction was determined by the residual standard deviation (RSD).

5. Total body water could be predicted with nearly equal accuracy from live weight or isotope-dilution space (RSD 0·025 and 0·020 respectively). Prediction of carcass protein was more accurate from live weight (RSD 0·033) than from TOH space (RSD 0·036), and inclusion of both variables resulted in only a marginal decrease in RSD to 0·031.

6. The prediction of carcass fat and energy was markedly improved by the inclusion of isotope-dilution space in conjunction with live weight compared with live weight alone.

7. The relations show the developmental nature of body composition of domestic fowl given diets adequate in nutrients. The prediction equations demonstrate the precision possible for studies in which estimates of body composition in poultry are required without slaughter.
Changes in the activity of skeletal muscle calcium-activated neutral proteinase (EC3. 4. 22. 17) and its specific inhibitor in chickens grown at different rates in response to graded levels of dietary protein
Authors: Ballard R. , Bardsley R. G. , Buttery P. J.
Published: May 2005

1. Two experiments are reported in which the effect of alteration in growth rate on the levels of avian skeletal muscle calcium-activated neutral proteinase (EC3.4.22. 17) (CANP or calpain) and its specific inhibitor (calpastatin), a system thought to be implicated in myofibrillar catabolism, was studied by means of manipulation of dietary protein concentration.

2. In Expt 1 broiler chicks were given free access to diets containing 105, 149, 197 and 212 g protein/kg for 20 d. In Expt 2 the four dietary treatments were 119, 141, 182 and 227 g protein/kg diet given for 16 d. Chick growth rate and total leg skeletal muscle weight significantly increased (P< 0·001) with increasing dietary protein concentration in both experiments. Total skeletal muscle protein increased with the level of dietary protein, the effect being significant (P< 0·01 andP< 0·001 in Expts 1 and 2 respectively).

3. Minced leg muscle was homogenized in low-salt buffers, and the extract chromatographed on DEAE-cellulose to separate proteinase and inhibitor activity. The partially purified CANP enzyme and inhibitor proteins were present at a concentration broadly consistent with literature reports, and their elution characteristics and Ca2+concentration dependence were not varied by dietary protein concentration.

4. Both the muscle CANP and CANP inhibitor activities (units/kg muscle) exhibited upward trends with growth rate and increased muscle weight. However, these differences were not statistically significant (P> 0·05) and were not present at all when the results were expressed as units/g muscle protein.
Effect of experimental zinc deficiency and repletion on some immunological variables in guinea-pigs
Authors: Verma P. C. , Gupta R. P. , Sadana J. R. , Paul Gupta R. K.
Published: May 2005

1. Cellular and humoral immune responses were studied in guinea-pigs fed on zinc-deficient (ZnD), Zn-adequate (control) and Zn-replete diets containing 1·25, 50 and 100 mg Zn/kg diet respectively.

2. It was found that the ZnD guinea-pigs had significantly decreased ability to elicit delayed-type hypersensitivity (DTH) response against sheep erythrocytes as compared with controls on the 9th day of immunization. This was further substantiated by histological examination of DTH-positive skin sections.

3. A significant reduction in direct splenic plaque-forming-cell response and haemagglutinating-antibody titre was also observed in ZnD guinea-pigs.

4. Serum electrophoretic studies revealed a highly disordered protein profile with a significantly depressed value for γ-globulin.

5. Zn repletion of the previously ZnD group resulted in marked, though incomplete, restoration of immunological responses.
Determination of leucine metabolism and protein turnover in sheep, using gas–liquid chromatography–mass spectrometry
Authors: Krishnamurti C. R. , Janssens S. M.
Published: May 2005

1. Whole-body protein synthetic rates in non-pregnant ewes were determined by the continuous infusion of L-[15N]- and [1-13C]leucine and measuring the plasma enrichment of leucine, α-ketoisocaproate (α-KIC) and expired carbon dioxide by gas–liquid chromatography–mass spectrometry.

2. The mean whole-body protein synthesis estimated from plasma leucine flux corrected for oxidation was 5·38 (SE 0·54) g/kg per d.

3. Under the conditions of the present study leucine oxidation was 0·323 (SE 0·067) mmol/kg per d and accounted for 10·71 (SE 2·26) % of plasma [13C]leucine flux. Deamination of leucine was 0·55 (SE 0·035) mmol/kg per d and accounted for approximately 17% of plasma [15N]leucine flux.

4. The rate of α-KIC reamination to leucine, calculated by subtracting 13C flux from 15N flux, was 0·228 (SE 0·101) mmol/kg per d.

5. The rate of whole-body protein degradation was 4·49 (SE 0·54) g/kg per d and there was a net protein gain of 0·89 (SE 0·21) g/kg per d.
Selenium balance studies in apparently healthy and housebound elderly people eating self-selected diets
Authors: Bunker Valda W. , Lawson Margaret S. , Stansfield Maureen F. , Clayton Barbara E.
Published: May 2005

1. Metabolic balance studies (5 d) for Se were conducted in twenty-four apparently healthy elderly people (age 69·6–85·4 years), and twenty housebound subjects (age 69·9–85·1 years) with chronic disease. During the study the subjects lived in their own homes, ate self-selected diets and continued their normal daily activities.

2. Geometric mean daily dietary intakes of the two groups were significantly different (P< 0·01), being 819 (range 310–1631) nmol for the healthy and 475 (range 233–1136) nmol for the housebound elderly.

3. Daily intake of Se significantly correlated with balance in both groups. Solution of the regression equations gave theoretical daily requirements of 447 nmol for the healthy and 419 nmol for the housebound subjects. The healthy elderly were in positive balance of 148 nmol/d for Se and the housebound were in equilibrium with an overall mean retention of 43 nmol/d.

4. Mean levels of Se in blood fractions for the healthy and housebound subjects were significantly different, being 1·65 and 1·40 μmol/l whole blood, 1·45 and 1·21 μmol/l plasma and 5·72 and 5·30 nmol/g haemoglobin in erythrocytes respectively. There was no difference in the whole-blood glutathione peroxidase (EC1.11.1.9) activities between the two groups.

5. There were clear differences in Se status between the two groups of elderly people. The cause of the positive balance in the healthy subjects remains unexplained.
Energy, protein, zinc and copper status of twenty-one elderly inpatients: analysed dietary intake and biochemical indices
Authors: Thomas Anita J. , Bunker Valda W. , Hinks Leslie J. , Sodha Nidish , Mullee Mark A. , Clayton Barbara E.
Published: May 2005

1. Duplicate diet analysis for energy, protein, zinc and copper with estimates of biochemical status for Zn and Cu were undertaken in twenty-one elderly long-stay inpatients (mean age 82 (range 63–89) years) consuming their customary hospital diet and in a stable medical condition. Fourteen patients had a long-standing and significant healing problem, either a leg ulcer or pressure sore.

2. Mean daily intakes of energy (5·2 MJ), protein (45 g), Zn (85 μmol) and Cu (14 μmol) were low in comparison with both official recommendations and levels of intake at which metabolic equilibrium was observed in healthy elderly people studied by the same methods (Bunkeret al.1984a).

3. Mean leucocyte Zn (9 pmol/106cells) and Cu (7·5 pmol/106cells) were low in comparison with results from healthy elderly people (Bunkeret al.1984a), implying suboptimal status for these elements. Those patients with healing problems tended to have the lower values within the range.

4. Recommendations are made with respect to improving nutritional status in this disadvantaged group of people.
Stable isotope metabolic studies of zinc nutrition in slum-dwelling lactating women in the Amazon valley
Authors: Jackson M. J. , GIugliano R. , Giugliano L. G. , Oliveira E. F. , Shrimpton R. , Swainbank I. G.
Published: May 2005

1. Zinc metabolism has been studied in a group of undernourished, slum-dwelling, lactating women in Manaus, Brazil, by means of modified metabolic balance techniques and the stable isotope 67Zn.

2. The subjects were found to be consuming a diet which provided an average of 34% of the recommended dietary allowance for lactating women, but six of the seven appeared to achieve Zn balance. In five of the subjects use of 67Zn in a stable isotope dilution manner demonstrated that they were absorbing a high proportion of the dietary Zn (proportional absorption ranged from 0·59 to 0·84), suggesting an adaptation to the chronically low intake.

3. Two subjects had marginally low plasma Zn concentrations, although hair, urine and milk Zn contents were all within accepted normal values.

4. Preliminary findings on the rate of plasma Zn turnover and the size of the exchangeable body Zn pool obtained using 67Zn suggest that these subjects may have a reduction in both.
Iron absorption from fortified flat breads
Authors: El Guindi Mohamed , Lynch Sean R. , Cook James D.
Published: May 2005

1. Radio-iron absorption measurements were performed in healthy volunteer subjects to assess the availability of fortification Fe added to various bread products.

2. When ferrous sulphate was used as a fortifier, Fe absorption from a traditional Egyptian flat bread (Baladi) averaged only 16% of that observed with European bread. This difference was attributed to the high extraction flour used to prepare Baladi bread.

3. The inhibiting effect of Baladi bread was largely eliminated by adding EDTA to the flour before baking.
Bile acid and cholesterol excretion in human beings given soya-bean-and meat-protein-based diets: a study in ileostomy subjects
Authors: Bosaeus Ingvar , Sandström Brittmarie , Andersson Henrik
Published: May 2005

1. The effect of partial replacement of meat protein with three different soya-bean-protein products on bile acid and cholesterol excretion was studied in seven ileostomy subjects. Four different test diets containing 60 g meat, rice and bread protein, or a replacement of 250 g protein/kg total dietary protein by soya-bean protein from soya-bean flour, soya-bean concentrate or soya-bean isolate, were randomly assigned to the subjects in 2-d periods.

2. Ileostomy contents were collected at 2-h intervals during the day and in one portion during the night, and immediately deep-frozen to avoid bacteriological degradation. Bile acids and cholesterol were quantified by gas-liquid chromatography.

3. No difference in daily excretion of bile acids and cholesterol was noted between test diets. Ileostomy sterol concentrations were lower when soya-bean products were fed.

4. Incorporation of moderate amounts of soya-bean products in solid diets does not seem to affect short-term sterol balance in man.
The effect of guar gum on the distribution of a radiolabelled meal in the gastrointestinal tract of the rat
Authors: Brown Nicola J. , Worlding Jane , Rumsey R. D. E. , Read N. W.
Published: May 2005

1. The effect of addition of guar gum (5 and 10 g/l) to a radiolabelled, homogenized, baked-bean test meal on the distribution of that meal in the gastrointestinal tract was investigated in groups of male rats killed at 25, 50, 100, 200, 300 and 400 min after gavage.

2. Addition of 5 and 10 g guar gum/l significantly increased the proportion of the meal remaining in the stomach at 25 and 50 min after gavage (P<0·01).

3. The heads of the control meal and meals containing guar gum reached the distal small intestine within 25 min after gavage but radioactivity was not observed in the caecum until 100 min after administration of each of the meals. Addition of guar gum (5 and 10 g/l) delayed caecal filling even though the head of each meal reached the caecum at the same time after gavage.

4. The geometric centres of guar-gum-containing meals were proximal to that of the control meal at all times after gavage.

5. The observed delay in the passage of a guar-gum-containing meal through the stomach and small intestine is probably due to the viscous nature of the meal resisting the propulsive and mixing effects of the gastrointestinal contractions, thereby reducing access of the glucose to the absorptive epithelium. This could contribute to the observed reductions in postprandial glycaemia seen in previous studies after incorporating guar gum into a meal.
Interaction of dietary carbohydrate and fat in the regulation of hepatic and extrahepatic lipogenesis in the rat
Authors: Herzberg Gene R. , Rogerson Maria
Published: May 2005

1. In order to examine the interaction of dietary fat and carbohydrate in the regulation of lipid metabolism, we have studied hepatic and extrahepatic lipogenesis, and adipose tissue lipoprotein lipase (EC3.1.1.34) in rats fed on one of the following diets: a fructose-based diet containing 0 (F0) or 150 g maize oil (F15)/kg, or a glucose based diet containing 0 (G0) or 150 g maize oil (G15)/kg.

2. The rats were meal-fed on the diets for 2 weeks after which the activities of a number of hepatic ‘lipogenic’ enzymes were measured and the activity of epididymal-fat-pad lipoprotein lipase. The activities of the lipogenic enzymes were: F0 > G0 > G15 > F15. Lipoprotein lipase activity was F0 = G0 = F15 = G15. The percentage of total body fatty acid synthesis which occurred in the liver was F0 > G0 > F15 > G15.

3. We conclude that fructose-induced hypertriglyceridaemia is primarily a result of the increased hepatic synthesis rather than decreased adipose-tissue lipoprotein lipase activity.
Effect of moderate magnesium deficiency on serum lipids, blood pressure and cardiovascular reactivity in normotensive rats
Authors: Luthringer Catherine , Rayssiguier Yves , Gueux Elyett , Berthelot Alain
Published: May 2005

1. Weanling Wistar rats were pair fed for 10 weeks on a purified diet containing either normal or suboptimal quantities of magnesium (960 or 80 mg/kg respectively).

2. At week 2, hypomagnesaemia was accompanied by hypertriglyceridaemia, an increase in plasma cholesterol and a decrease in high-density-lipoprotein-cholesterol in animals fed on the Mg-deficient diet. At week 10, the increase in triglycerides observed in Mg-deficient animals was less marked while the increase in total cholesterol was more important.

3. During the whole experimental period, Mg-deficient animals never showed hypertension. At week 2, mean arterial blood pressure was significantly lower in Mg-deficient rats than in their respective controls, while heart rate was significantly increased. However, hypotension accompanied by tachycardia was a transitory phenomenon which appeared only in the early phase of deficiency.

4. Vascular reactivity was studied in vagotomized anaesthetized rats after ganglionic blockade with pentolinium and atropine sulphate. The reactivity to noradrenaline was significantly higher in Mg-deficient rats compared with pair-fed controls after 2 weeks on the experimental diet.
The effects of dietary folate and zinc on the outcome of pregnancy and early growth in rats
Authors: Fuller N. J. , Evans P. H. , Howlett M. , Bates C. J.
Published: May 2005

1. The objective of the present study was to determine the effects of two levels of folic acid and two levels of zinc in the diets of rats during pregnancy and lactation. It addressed, among other things, the question of whether an inhibitory effect of folic (pteroylmonoglutamic) acid on Zn absorption might result in a secondary Zn deficiency in either the dams or the pups.

2. A purified diet was given to four groups of female DNL (Norwegian) Hooded rats, before and during pregnancy and during lactation. It contained the four possible combinations of: no added folic acid or 100 μg added pteroylmonoglutamic acid/g, and 6·6 or 20·2 μg Zn/g. Pups and dams were killed on day 20 of gestation or on day 20 postpartum. Measurements of body-weights, food intakes, blood folate and tissue Zn levels were performed.

3. The group with low Zn and low folate intake had a satisfactory reproductive outcome, and there were only minor effects of the supplements on body-weights.

4. Additional folate greatly increased blood (erythrocyte and plasma) folate levels, but did not compromise tissue Zn concentrations. Zn supplementation also enhanced blood folate levels, for reasons which are not yet clear.

5. There was a moderate enhancing effect of the Zn supplement on Zn levels in the livers and kidneys of pregnant dams, and the kidneys of lactating dams.

6. If the conclusions can be extrapolated to humans, then the results provide some reassurance that a high folate intake from prenatal supplementation need not necessarily cause Zn depletion, and hence functional Zn deficiency in pregnant women and their offspring.
Comparison of γ-glutamyl hydrolase (conjugase;EC3. 4. 22. 12) and amylase treatment procedures in the microbiological assay for food folates
Authors: Pedersen Jens C.
Published: May 2005

1. It has been suggested that deconjugation of food folates with pig kidney, compared with chicken pancreas, may increase measureable folate by approximately 50% (Phillips & Wright, 1983). Therefore deconjugation with conjugases from these two enzyme sources was optimized and compared. Folate was measured microbiologically withLactobacillus casei(ATCC 7469) as the test organism at pH 5·6.

2. Treatment for 6 h with 200 mg pig kidney/200 mg sample was compared with the conventional assay employing overnight incubation with 20 mg chicken pancreas/5 g sample. Comparison of the deconjugation systems showed chicken pancreas to be superior for peas (Pisum sativum) and beans (Phaseolus vulgaris), while there was no difference for potatoes.

3. γ-Glutamyl hydrolase (conjugase;EC3. 4.22. 12) treatment for 2 and 20 h with pig kidney and chicken pancreas was optimized for raw potatoes and green frozen peas. Treatments with pig kidney were conducted at pH 4·6, which is optimal, and at pH 5·2. There was no significant difference between 2 and 20 h treatments at pH 5·2. Treatments with chicken pancreas were conducted at pH 6·1. Treatment for 2 h was preferred as it resulted in significantly higher measureable folate activity in peas and potatoes, and because overnight treatment can be influenced by microbial production of folate.

4. With optimal treatment conditions the source of enzymes did not significantly influence measureable folate activity. Chicken pancreas is the traditional source of conjugase in Scandinavia and was preferred for deconjugation.

5. Chicken pancreas, 20 and 60 mg, was used for deconjugation of sixteen different food samples, each containing approximately 200 ng folate. Chicken pancreas at 60 mg/sample gave significantly higher results. Further addition of enzyme did not increase the folate values.

6. A combined amylase treatment using heat-resistant α-amylase (EC3.2.1.1) during extraction to ensure the gelatinization of the sample, and glucan 1,4-α-glucosidase (amyloglucosidase;EC3.2.1.3), along with the incubation with chicken pancreas to complete the digestion, was shown to give a small but significant increase in folate values of starch-containing samples.

7. Folate results using the recommended procedure are given for raw potatoes, wheat bran, rolled oats, wheat flour and dark rye bread.

8. Chicken pancreas was shown to contain equally high amounts of amylases as did the α-amylase and amyloglucosidase sources. This finding may explain the relatively small benefit of a specific amylase addition.
Evidence that adverse effects of zinc deficiency on essential fatty acid composition in rats are independent of food intake
Authors: Cunnane Stephen C.
Published: May 2005

1. Young male rats were fed on diets containing 3·4, 36 or 411 mg zinc/kg for 10 weeks in order to determine whether effects of Zn deficiency on plasma and liver essential fatty acid composition could be distinguished from those of reduced protein and energy intake.

2. Fatty acid analysis revealed that a Zn intake of 3·4 mg/kg (plasma Zn 0·80 v. 1·97 mmol/l in controls fed on 36 mg Zn/kg) resulted in a significant increase in the linoleic acid: arachidonic acid ratio in both plasma and liver phospholipids in comparison with rats fed on 36 or 411 mg Zn/kg.

3. Zn supplementation (411 mg/kg) decreased the linoleic acid: arachidonic acid ratio in plasma phosphatidylserine compared with that of the controls.

4. The previously reported increase in arachidonic acid (mol %) in liver triacylglycerol of Zn-deficient rats was shown to be a function of a reduced liver triacylglycerol pool size; quantitatively, triacylglycerol content of arachidonic acid in the liver was not significantly affected by Zn intake.
Utilization of tryptophan, nicotinamide and nicotinic acid as precursors for nicotinamide nucleotide synthesis in isolated rat liver cells
Authors: Bender David A. , Olufunwa Ronald
Published: May 2005

1. Incubation of isolated rat hepatocytes with nicotinamide or nicotinic acid showed that while both vitamers were taken up from the incubation medium, neither was utilized to any significant extent as a precursor of the nicotinamide nucleotide coenzymes, NAD and NADP, and neither was capable of preventing the loss of nucleotides that occurs on incubating the cells.

2. Incubation of hepatocytes with tryptophan showed thatde novosynthesis from tryptophan permitted replacement of the nucleotides lost during incubation; at high concentrations of tryptophan there was an increase above the initial intracellular concentration of NAD(P). Incubation of hepatocytes with tryptophan also resulted in the formation and release from the cells of a considerable amount of niacin, as well as the two principal metabolities of NAD(P),N1-methyl nicotinamide and methyl pyridone carboxamide.

3. It is suggested that, in the liver, preformed niacin is not utilized for nucleotide synthesis, and indeed the function of the liver appears to be synthesis of niacin from tryptophan, and its release for use by extrahepatic tissues that lack the pathway forde novosynthesis of nicotinamide nucleotides from tryptophan.
Studies of the changes in systemic copper metabolism and excretion produced by the intravenous administration of trithiomolybdate in sheep
Authors: Mason J. , Lamand M. , Tressol J. C. , Mulryan G.
Published: May 2005

1. The effects of intravenous trithiomolybdate administration on the fate of 64Cu and on stable Cu metabolism were examined in sheep held in metabolism cages and fed on a low-Cu diet supplying 2·95 mg Cu/animal per d.

2. In Expt 1 the injection of trithiomolybdate, 30 mg molybdenum/sheep per d for 5 d, greatly increased plasma Cu levels and more than doubled the faecal Cu excretion. Urinary Cu excretion was unaffected. The disappearance from plasma of 64Cu injected during the trithiomolybdate administration was slowed although faecal 64Cu excretion was increased more than threefold.

3. In Expt 2 trithiomolybdate, 10 and 30 mg Mo/sheep per d for 3 d, was administered 22 h after the injection of 64Cu. Radioactivity reappeared immediately in plasma and faecal 64Cu excretion was increased.

4. In both experiments the 64Cu and the increased stable Cu in plasma were associated with albumin.

5. The experiments explain the effectiveness of thiomolybdates as ‘decoppering’ agents and provide a model for some of the systemic effects seen in ruminants exposed to increased dietary Mo. The experiments support the view that the thiomolybdates, by causing the appearance of new ligands, alter the distribution of Cu in tissues and cause an overall depletion.