bluuebunny/crossref_metadata_2025 huggingface dataset:
Protein turnover rates of two human subjects during an unassisted crossing of Antarctica
Authors: Stroud M. A. , Jackson A. A. , Waterlow J. C.
Published: June 2005

During the Austral summer of 1992–3, two men, MS and RF, walked 2300 km across Antarctica in 96 d, unassisted by other men, animals or machines. During the journey they ate freeze-dried rations, towed on sledges, that contained an average of 21·3 MJ/d of which 56·7% was fat, 35·5% carbohydrate and 7·8% protein (98·8 g). Despite this high energy intake both men lost more than 20 kg in body weight due to their extremely high energy expenditures. Studies of protein turnover using [15N]glycine by the single-dose end-product method were made before, during and after the journey, and these demonstrated considerable differences in the metabolic responses of the two men to the combined stresses of exercise, cold and undernutrition. However, both men maintained high and relatively stable levels of protein synthesis during the expedition despite the great exertion and the onset of considerable debilitation. This stability indicates the vital physiological function of protein synthesis.
Fate of fructo-oligosaccharides in the human intestine
Authors: Alles Martine S. , Hautvast Joseph G. A. J. , Nagengast Fokko M. , Hartemink Ralf , Van Laere Katrien M. J. , Jansen Jan B. M. J.
Published: June 2005

There is a need for studies on colonic fermentation in order to learn more abouthealth and diseases of the colon. The aim of the present study was to evaluate the fate of twodifferent doses of fructo-oligosaccharides (5 and 15 g/d) v. glucose in the intestine of healthy men. Twenty-four volunteers participated in a 5-weekstudy. The study was a completely balanced multiple crossover trial using an orthogonal Latin-square design for three periods, with supplement periods of 7 d and two 7 d wash-out periods. Breath samples and faecal samples were collected. There was a clear gaseous response to the consumption of fructo-oligosaccharides. The highest dose significantly increased 24 h integratedexcretion of breath H2 (P < 0·05). Breath H2 excretion after ingestion of 5 g fructo-oligosaccharides was higher than control, but did not reach significance. No effects on the total concentration of short-chain fatty acids in faeces were observed, no modification of the molar proportions of the various short-chain fatty acids was observed. The faecal pH did not change. No changes in faecal weight were observed. No fructo-oligosaccharides were recovered in faeces. We conclude that fructo-oligosaccharides added to the diet of young Western subjects are fully metabolized in the large intestine. The level of fermentation seems to be dose-dependent.
Tissue hypertrophy and epithelial proliferation rate in the gut of rats fed on bread and haricot beans (Phaseolus vulgaris)
Authors: Key Fiona B. , McClean Devina , Mathers J. C.
Published: June 2005

The present study was designed to test the hypothesis that increasing short-chain fatty acid (SCFA)production in the large bowel increases gut epithelial proliferation rate (EPR). Two experiments were carried out in which rats were fed on bread (wholemeal or white)-based diets containing graded amounts of cooked haricot (Phaseofus vulgaris) beans; the latter are a rich source of fermentable carbohydrates. Consumption of beans was associated with several-fold increases in SCFA production with the greatest relative increase being for butyrate. Despite the very large increase in SCFA production, there was no evidence that this had any effect on EPR in the duodenum. Where the basal diet contained wholemeal bread (Expt 1) there was no effect of enhanced SCFA supply on EPR in either the caecum or colon, but with the white bread-based diet (Expt 2) adding beans produced increments in both SCFA supply and EPR in the caecum. Evidence that SCFA are responsible for enhanced EPR above normal levels is not convincing. In those instances where enhanced SCFA supply is associated with increased EPR, the increase may be (1) from a hypoproliferative state towards normal, (2) a transient phenomenon accompanying tissue hypertrophy or (3) a homeostatic response to increased cell loss by cell sloughing or apoptosis. It is not likely that there is any direct link with risk of colon cancer
Iron nutrition and anaemia in a malaria-endemic environment: haematological investigation of the Gidra-speaking population in lowland Papua New Guinea
Authors: Nakazawa Minato , Ohtsuka Ryutaro , Kawabe Toshio , Hongo Tetsuro , Inaoka Tsukasa , Akimichi Tomoya , Suzuki Tsuguyoshi
Published: June 2005

Blood examination was conducted for the four Gidra-speaking village groups in Papua New Guinea, who were characterized by high Fe intake and high malaria prevalence with marked inter-village differences. The northern riverine villagers, whose Fe intake was higher than the other three village groups, did not suffer from Fe-deficiency anaemia in their malaria-endemic environment; nor did the inland villagers, with their second highest Fe intake and their malaria-free environment, suffer from Fe-deficiency anaemia. However, several individuals of the southern riverine village suffered from anaemia in a malaria-endemic environment, although their Fe intake was almost the same as the inland villagers’. A considerable proportion of the coastal villagers were anaemic, reflecting the lowest Fe intake and the highest malaria prevalence. An inter-village comparison of the relationships between haemoglobiin levels and transferrin saturation revealed that the southern riverine villagers needed smaller amounts of circulating Fe for erythropoiesis than the northern riverine and inland villagers, reflecting the long-term human-environment conditions such as the density of malaria vectors and the people’s dietary habits. Fe supplementation was not judged effective against hypoferraemia and/or anaemia in such a population. As the incidence of malaria had no significant long-lasting effect on Fe stores or circulating Fe concentration, but did have an effect on anaemia, the hypothesis that malaria causes a transfer of Fe from the blood to parenchymal tissues as a defence against infectious diseases was not supported.
Utilization of endogenous and dietary urea in the large intestine of the mature horse
Authors: Martin R. G. , McMeniman N. P. , Norton B. W. , Dowsett K. F.
Published: June 2005

The dynamics of N metabolism in mature horses were investigated when they were fed on a low-N diet or the same diet supplemented with sufficient urea or soyabean meal to meet their theoretical N requirements. There were no differences in DM, organic matter or neutral-detergent-fibre digestibilities for the three diets. N digestibilities and digestible-N intakes were similar for the urea- and soyabean-supplemented diets and very low for the low-N diet. For all three diets plasma urea was degraded in the digestive tract to NH3which was utilized by the bacterial population as a N source. NH3was absorbed from the large intestine into the blood and converted to urea. NH3was also incorporated into plasma proteins. The horses fed on the low-N diet degraded a greater proportion of endogenous urea in the digestive tract than did horses fed on the urea- or soyabean-supplemented diets. However, the horses fed on the urea diet had the highest degradation rate of urea. The quantity of urea degraded in the digestive tract of horses fed on the urea-supplemented and the low-N diets could not compensate for a lack of dietary crude protein in these diets. The horses were in a negative N balance when fed on the low-N and urea-supplemented diets and a positive N balance when fed on the soyabean-supplemented diet. Dietary urea supplementation did not benefit the horses.
Changes in the concentration of fructose in the blood of piglets of different ages after doses of fructose, fructose plus glucose, and sucrose
Authors: Bird P. H , Hartmann P. E
Published: June 2005

We investigated the hydrolysis of sucrose in the small intestine and the subsequent absorption and metabolism of fructose in sucking piglets by measuring temporal changes in the concentration of fructose in the plasma following the administration of physiological amounts of these carbohydrates. Calculations of the area under the curve for fructose in the plasma showed that there was no age limit to the piglets'ability to absorb fructose. However, there was a limit to the amount of fructose that the younger piglets could get from a dose of sucrose. Indeed, we demonstrated that there was a positive linear correlation between a piglet's capacity to hydrolyse sucrose and the age of the piglet up to 15 d of age (r 0·98).The half-life for fructose was 495, 103, 38, 49 and 28 min in 2-, 5-, 7-, 10- and 15-d-old piglets respectively and, thus, there was only limited utilization of fructose in the younger piglets. However, there were 13·0- and 1·4-fold increases in the elimination rate of fructose from the plasma of piglets from 2 to 7 d and from 7 to 15 d respectively, consistent with the reported increase in the deposition of fat in piglets of a similar age range. Hence, the effective metabolism of fructose may bepartially dependent on the amount of adipose tissue present and the phosphorylation of this monosaccharide by hexokinase (EC 2·7·1·1) in this tissue.
Maintenance of villus height and crypt depth, and enhancement of disaccharide digestion and monosaccharide absorption, in piglets fed on cows' whole milk after weaning
Authors: Pluske John R. , Thompson Melinda J. , Atwood Craig S. , Bird Peter H. , Williams Ian H. , Hartmann Peter E.
Published: June 2005

The aims of the present study were (a) to maintain the structure and function of the small intestine of the piglet after weaning, and (b) to compare the capacityin vivoof sucking and weaned piglets to digest oral boluses of lactose and sucrose and absorb their monosaccharide products. Piglets were fed on cows' whole milk ad libitum every 2 h for 5 d after weaning. Physiological doses of lactose plus fructose (treatment LAC + FRU) and sucrose plus galactose (treatment SUC + GAL) were administered on day 27 of lactation and on the fifth day after weaning, after which time piglets were killed. Villus height and crypt depth were maintained (P > 0·05) by feeding cows' milk after weaning. The areas under the curves (AUC) for galactose and glucose, adjusted for live weight and plasma volume, increased (P < 0·05) after weaning. Despite the enhancement of gut function after weaning, the galactose index (Gall: AUC for galactose ingested as lactose divided by the AUC for the same dose of galactose ingested as the monosaccharide) and fructose index (FruI: AUC for fructose ingested as sucrose divide by the AUC for the same dose of fructose ingested as the monosaccharide), which are indices of digestive and absorptive efficiency, both decreased after weaning. This apparent anomaly may be reconciled by increased growth, and hence surface area, of the small intestine between weaning and slaughter such that ‘total’ digestion and absorption most probably increased despite apparent decreases in GalI and FrnI. Positive correlations (P < 0.05) between villus height and Gall are consistent with the maximum activity of lactase occurring more apically along the villus. Significant linear relationships (P < 0·05) were recorded between villus height at the proximal jejunum and adjusted AUC for galactose and glucose following treatment LAC + FRU, and between villus height at the proximal jejunum and adjusted glucose AUC following treatment SUC + GAL. These relationships suggest that maximum digestion and absorption occurs at increasing distances along the crypt:villus axis in the weaned pig.
The relationships between dietary α-linolenic: linoleic acid and rat platelet eicosapentaenoic and arachidonic acids
Authors: Leece Elizabeth A. , Allman Margaret A.
Published: June 2005

Increased dietary intake of α-linolenic acid (ALA) may be desirable to enrich tissue eicosapentaenoic acid (EPA; 20:5n-3) but competition betweenn-3 andn-6 fatty acids for enzymes involved in elongation and subsequent acylation will determine the relative proportions of phospholipid fatty acids. The aim of the present study was to examine the effects of altering the dietary ALA: linoleic acid (LA) ratio on rat platelet EPA and arachidonic acid (AA; 20:4n-6) concentrations. Sprague Dawley rats were fed on diets containing 30% total energy as fat with approximately 10% each of saturated, monounsaturated and polyunsaturated fatty acids with one of the following ALA:LA values; 1:7, l:4, l:1 or 1.3:1 (nine rats per group). After 4 weeks, blood was withdrawn from the abdominal aorta and platelet fatty acids analysed. The proportion of EPA was greater at the 1:1 and 1·3:1 ratios compared with the 1:7 and 1:4 (P < 0·05), and a decrease in AA was observed (P < 0·05) at the higher ratios. It was established that the platelet EPA:AA value increased (P < 0·05) as the dietary ALA:LA value increased
Dietary supplementation and rapid catch-up growth after acute diarrhoea in childhood
Authors: Hoare Simon , Poppitt Sally D. , Prentice Andrew M. , Weaver Lawrence T.
Published: June 2005

Diarrhoea is a major cause of short-term growth faltering in children of the developing world. If catch-up weight gain is delayed by inadequate dietary intake, or by further bouts of diarrhoea, progressive growth failure occurs. To test the hypothesis that early refeeding is as effective as later feeding after acute diarrhoea with weight loss, we measured the effects of a timed dietary intervention on weight gain after acute diarrhoea in underweight Gambian children. Thirty-four children aged 4–22 months with weight loss following acute diarrhoea were given a high-energy-protein supplement for 14 d beginning either immediately after rehydration or a fortnight later. With a 50% increase in energy intake and a 100% increase in protein intake there was a rapid and highly significant (P < 0.001) gain in weight within a fortnight whether the supplement was given immediately or 2 weeks after presentation. Rates of weight increase were similar whether supplementation was provided early or late, but over the full 28 d (of intervention and non-intervention) children who received late supplementation had greater overall weight gain (P < 0.02) than those supplemented early. Vigorous and early feeding with a high-energy-protein supplement should be central to the management of malnourished children with acute diarrhoea in developing countries, and may be as important as control of diarrhoea in preventing malnutrition and growth failure. This may be achieved in the community using IocaUy available foods, in the face of continuing diarrhoea
Microbial amino acid synthesis and utilization in rats: incorporation of15N from15NH4Cl into lysine in the tissues of germ-free and conventional rats
Authors: Torrallardona David , Harris C. Ian , Coates Marie E. , Fuller Malcolm F.
Published: June 2005

The absorption of lysine synthesised by the gastrointestinal microflora was estimated by comparing the15N incorporated into body lysine in four germ-free (15N-GF) and four conventional (15N-CV) rats. They were fed for 10d on a protein-free diet containing fermentable carbohydrates and15NHM4Cl; another four conventional rats (control), fed on the same diet but with unlabelled NH4Cl, were used to estimate the natural abundance of15N. The eviscerated carcass of each rat was homogenized and a sample hydrolysed. Lysine was isolated by ion-exchange chromatography and its15N enrichment was measured by isotope-ratio mass spectrometry. The15N-CV rats significantly incorporated15N into their body lysine. The15N-GF rats had a statistically significant, although small, incorporation of15body lysine, probably arising from a measurement artifact. It was concluded, therefore, that all [15N]lysine was of microbial origin. The total lysine content in the body and the15N enrichment of lysine in the microbial fraction of the faeces of the15N-CV rats were also determined. The amount of microbial lysine absorbed by the15N-CV rats was estimated by dividing the total amount of [15N]lysine in the body by the enrichment of microbial lysine. It was estimated that the daily absorption of microbial lysine by the conventional rats was 21·3 (SE 2·04) mg/kg body weight0·75
Microbial amino acid synthesis and utilization in rats: the role of coprophagy
Authors: Torrallardona David , Harris C. Ian , Fuller Malcolm F.
Published: June 2005

Four rats were housed in cages with mesh floors; another four rats were housed in tubular anti-coprophagy cages, in which they could not turn round to reach their own faeces. Both groups were fed for 6 d on a low-protein diet containing fermentable carbohydrates and 15NH4Cl. At the end of the experiment the rats were killed and their carcasses were homogenized, lysine was isolated by ion-exchange chromatography and its 15N enrichment measured by isotope-ratio mass spectrometry. The 15N enrichment in the lysine of the microbial fraction of faeces and the total amount of lysine in the body were also determined in order to estimate the amount of microbial lysine absorbed. The 15N enrichment in body lysine of non-coprophagic rats was not different from that previously measured in rats given unlabelled NH4Cl, but in coprophagic rats it was significantly higher. The daily absorption of microbial lysine by the coprophagic rats accounted for 20·7 (SE 2·55) mg/kg body weight0·75 but was only 0·5 (SE 1·04) mg/kg body weight0·75 for the non-coprophagic rats. This value was not significantly different from zero. The utilization of microbial amino acids via coprophagy resulted in a higher weight gain (adjusted for intake) in the coprophagic group (15·5 g/6 d) than in the non-coprophagic rats (3·1 g/6 d). It was concluded that, in rats, the utilization of microbial lysine occurred exclusively via coprophagy.
The effect of long-term calcium supplementation on indices of iron, zinc and magnesium status in lactating Gambian women
Authors: Yan Liya , Prentice Ann , Dibba Bakary , Jarjou Landing M. A. , Stirling Dorothy M. , Fairweather-Tait Susan
Published: June 2005

The effect of long-term supplementation with CaCO3 on indices of Fe, Zn and Mg status was investigated in a randomized, double-blind intervention study of sixty lactating Gambian women. The supplement contained 1000 mg Ca and was consumed between meals 5 d/week, for 1 year starting 1.5 weeks postpartum. Compliance was 100%. Plasma ferritin concentration, plasma Zn concentration and urinary Mg output were measured before, during and after supplementation at 1.5, 13, 52 and 78 weeks postpartum. No significant differences in mineral status were observed at any time between women in the supplement and placebo group. Analysis of the longitudinal data series showed that plasma ferritin and Mg excretion were characteristic of the indivdiual (P < 0·001). Within individuals, ferritin concentration was higher at 1.5 weeks postpartum than later in lactation (P = 0.002). Plasma Zn concentration was lower at 1.5 weeks postpartum than at other tima (P < 0·001), an effect which disappeared after albumin correction. Low plasma concentrations of ferritin and Zn indicated that the Gambian women were at high risk of Fe and Zn deficiency. Measurements of α1-antichymotrypsin suggested that the results were not confounded by acute-phase responses. The results of the present study indicate that 1000 mg Ca as CaCO3 given between meals does not deleteriously affect plasma ferritin and Zn concentrations or urinary Mg excretion in women who are at risk of Fe and Zn deficiency
Diets deficient in selenium and vitamin E affect plasma lipoprotein and apolipoprotein concentrations in the rat
Authors: Mazur A , Nassir F , Gueux E , Moundras C , Bellanger J , Grolier P , Rock E , Rayssiguier Y
Published: June 2005

The present study examined the effects of Se, vitamin E and combined Se and vitamin E deficiencies in rats on plasma lipid, Lipoprotein and apolipoprotein (apo) concentrations. Deficiencies were induced by feeding rats the respective diets for 6 weeks. The study shows that Se deficiency results in increased concentrations of plasma cholesterol and apo E. Both could be explained by an increase in the HDL1 fraction. Vitamin E deficiency alone had no significant effect on plasma lipid, lipoprotein and apo concentrations. Se deficiency in combination with vitamin E deficiency leads to an increase in plasma LDL and apo B concentrations. These results point to the need for further investigations on the mechanism by which Se deficiency affects lipoprotein metabolism.
Copper homeostasis in rats fed on a high-sulphide diet
Authors: Yu Shiguang , Beynen Anton C.
Published: June 2005

The mechanism underlying the reduced Cu status in rats fed on a high-sulphide diet was investigated. Male rats aged 6 weeks were fed ad libitum on purified diets containing either 0 or 500 mg S2-/kg and demineralized water for a period of 2 weeks. The high-sulphide diet had no effect on feed intake, body-weight gain or weight of liver and kidney bat significantly reduced Cu concentrations in plasma and kidney. Biliary Cu excretion was decreased significantly in rats fed on the high-sulphide diet. Apparent Cu absorption (Cu intake -faecal Cu) and true Cu absorption (Cu intake - (faecal Cu - biliary Cu)) were significantly lowered after sulphide feeding for 2 weeks. Rats fed on the high-sulphide diet excreted less Cu in urine than did the controls. We conclude that high sulphide intake reduces Cu status in rats through inhibition of Cu absorption which is reflected by a decrease in biliary Cu excretion as a secondary feature
Consequences of reduced fibre intake on digestion, rate of passage and caecal microbial activity in the young rabbit
Authors: Bellier R. , Gidenne T.
Published: June 2005

The present work was undertaken to studyin vivofibre degradation, rate of passage and caecal fermentation activity (CFA) in the young rabbit (7 weeks old) receivingad lib. a control (C) or a lowfibre (LF) diet (400 and 220 g neutral-detergent fibre (NDF)/kg respectively). As a consequence of the 50% reduction in the dietary fibre level, the voluntary food intake of the rabbits decreased by 25%, and the daily fibre intake was reduced by 60% (26·7 and 10·8 g NDF/d for groups C and LF, respectively).In spite of a longer mean retention time of the fibre particles, the quantity of fibre digested daily was significantly lower (P<0·01) for the LF than for the C group (4·0 and 7·8 g NDF/d respectively). The circadian distribution of the faecal excretion (as a percentage of the total DM output) did not differ between diets (P= 0·52) and no interaction was found (P= 0·96) between diet and time of excretion. Also, variables describing the CFA showed no interactions between diet (C or LF) and time of sampling (during caecotrophy or during hard faeces excretion). Our results indicated no direct relationship between the quantity of fibre digested and the total short-chain fatty acid concentration in the caecum, but the fermentation pattern indicated lower proportions of acetate for the LF diet. Higher levels of diaminopimelic acid (DAPA) and ATP were found for the LF diet associated with an improved dietary fibre digestibility, suggesting a higher microbial activity. However, this effect was balanced by a lower caecal digesta turnover rate and the microbial biomass output estimated through the faecal DAPA output did not vary significantly
Urinary excretion of purine derivatives and tissue xanthine oxidase (EC 1.2.3.2) activity in buffaloes (Bubalis bubalis) with special reference to differences between buffaloes and Bos taurus cattle
Authors: Chen X. B. , Samaraweera L. , Kyle D. J. , Ørskov E. R. , Abeygunawardene H.
Published: June 2005

The urinary excretion of purine derivatives (PD) was measured in six buffaloes (Bubalis bubalis) during fasting and in fourteen buffaloes given four restricted levels of roughage (2·5-4·8 kg DM/d). Only allantoin and uric acid, not xanthine and hypoxanthine, were present in the urine, the pattern of excretion being similar to that in cattle. The fasting PD excretion amounted to 0·20 (SD 0·06) mmol/kg metabolic weight (W0·75) per d, and the rate of PD excretion as a linear function of feed intake was 5·2 mmol/kg digestible organic matter intake. Both values were considerably lower than the values for cattle reported in the literature. Creatinine excretion values were 0·33 (SD 0·06) and 0·44 (SD 0·09) mmol/kg W0.75 per d determined in fasting and feeding periods respectively. Fasting N excretion was 257 (SD 49) mg N/kg W0.75 per d. Both creatinine and fasting N excretions were also lower than in cattle. The activities of xanthine oxidase (EC 1.2.3.2) in plasma, liver and intestinal mucosa were determined in buffaloes, cattle and sheep. Xanthine oxidase activities in buffaloes were 24·5 (SD 2·7) unit/l plasma and 0·44 (SD 0·02) and 0·31 (SD 0·10) unit/g fresh tissue in liver and intestinal mucosa respectively. These activities were higher than those in cattle and sheep. Xanthine oxidase was practically absent from plasma and intestine of sheep. It is suggested that the differences in PD excretion between buffaloes and cattle were probably due to the smaller proportion of plasma PD that was disposed of in the urine of buffaloes.
Utilization of lipids during exercise in human subjects: metabolic and dietary constraints
Authors: Brouns Fred , van der Vusse Ger J.
Published: June 2005

During endurance exercise, skeletal muscle relies mainly on both carbohydrate (CHO) and fat oxidation to cover energy needs. Numerous scientific studies have shown that increasing the exercise intensity leads to a progressive utilization of CHO. The latter will induce a state of glycogen depletion which is generally recognized as being a limiting factor for the continuation of strenuous exercise. Different dietary interventions have been proposed to overcome this limitation. A high-CHO diet during periods of intense training and competition, as well as CHO intake during exercise, are known to maintain a high rate of CHO oxidation and to delay fatigue. However, it has been recognized also that enhancing fatty acid (FA) oxidation during exercise induces a reduced rate of glycogen degradation, resulting in an improved endurance capacity. This is most strikingly observed as a result of frequent endurance exercise which improves a number of factors known to govern the FA flux and the oxidative capacity of skeletal muscle. Such factors are: (1) blood flow and capillarization; (2) lipolysis of triacylglycerol (TAG) in adipose tissue and circulating TAG and transport of FA from blood plasma to the sarcoplasm; (3) availability and rate of hydrolysis of intramuscular TAG; (4) activation of the FA and transport across the mitochondrial membrane; (5) the activity of enzymes in the oxidative pathway; (6) hormonal adaptations, i.e. sensitivity to catecholamines and insulin. The observation that the plasma FA concentration is an important factor in determining the rate of FA oxidation, and that some dietary factors may influence the rate of FA supply to muscle as well as to the mitochondria, has led to a number of dietary interventions with the ultimate goal to enhance FA oxidation and endurance performance. It appears that experimental data are not equivocal that dietary interventions, such as a high-fat diet, medium-chain TAG-fat emulsions and caffeine intake during exercise, as well as L-carnitine supplementation, do significantly enhance FA oxidation during exercise. So far, only regular endurance exercise can be classified as successful in achieving adaptations which enhance FA mobilization and oxidation.
The effect of triacylglycerol-fatty acid positional distribution on postprandial metabolism in subcutaneous adipose tissue
Authors: Summers Lucinda K. M. , Fielding Barbara A. , Ilic Vera , Quinlan Paul T. , Frayn Keith N.
Published: June 2005

We hypothesized that fatty acids at thesn−2 position of chylomicron triacylglycerol are preferentially released into the venous plasma (rather than being taken up and stored in the adipocytes) after hydrolysis by lipoprotein lipase (EC3.1.1.34) in adipose tissue. Arterio–venous differences across adipose tissue were studied in eight healthy subjects on two occasions for 6 h after ingestion of different structured triacylglycerols rich in palmitic acid either at thesn−2 or thesn−1,3 positions. In particular the specific fatty acids making up lipoprotein fractions and plasma non-esterified fatty acids were analysed. After the different meals there were no differences between either postprandial arterialized or venous plasma metabolite concentrations. Chylomicron triacylglycerol extraction in adipose tissue was the same following the two types of fat. There was no difference between the specific fatty acid composition of the postprandial non-esterified fatty acid release from adipose tissue after ingestion of the two triacylglycerols, indicating that there was no preferential release of a saturated fatty acid at thesn−2 position.
Cholesterol lowering in pigs through enhanced bacterial bile salt hydrolase activity
Authors: Smet I. De , Boever P. De , Verstraete W.
Published: June 2005

The effect of feeding liveLactobacillus reutericells containing active bile salt hydrolase (BSH) on plasma cholesterol levels was studied in pigs. During an experiment lasting 13 weeks, twenty pigs were fed on a high-fat, high-cholesterol, low-fibre diet for the first 10 weeks, and a regular pig diet for the last 3 weeks. One group of animals received, twice daily, 11·25 (SD 0·16) log10colony forming units of the potential probiotic bacteria for 4 weeks (from week 3 until week 7). From week 8 onwards, the treated group was again fed on the same diet as the control group without additions. The total faecalLactobacilluscounts were only significantly higher in the treated pigs during the first 2 weeks ofL. reuterifeeding. Based on limited data, it was suggested that the administeredLactobacillusspecies had caused a temporary shift within the indigenousLactobacilluspopulation rather than permanently colonizing the intestinal tract. The probiotic feeding brought about significant lowering (P≤ 0·05) of total and LDL-cholesterol concentrations in the treated pigs compared with the control pigs, while no change in HDL-cholesterol concentration was observed. The data for faecal output of neutral sterols and bile salts were highly variable between the animals of each group, yet they indicated an increased output in the treated pigs. Although the blood cholesterol levels went up in both groups during the 3 weeks following theLactobacillusadministration period, significantly lower serum total and LDL-cholesterol levels were observed in the treated pigs. During the final 3 weeks of normalization to the regular diet, cholesterol concentrations significantly decreased in both animal groups and the differences in total and LDL-cholesterol concentrations between the groups largely disappeared.
The remedying of iron deficiency: what priority should it have?
Authors: Walker Alexander R. P.
Published: June 2005

Fe deficiency is considered to be the commonest of nutritional deficiencies worldwide. Adverse effects are stated to include lower growth rate and impaired cognitive scores in children and poor pregnancy outcome and lower working capacity in adults. In the present review, Fe intake, stores of the element, the magnitude of deficiencies and the benefits from interventions, as reflected in the results of clinical trials, are discussed. Because of inadequacies of knowledge in numerous respects, more information is needed regarding the extent to which clinical trials relate to public health realities, before introducing regional or national supplementation programmes. While Fe supplements are needed in certain groups, and in particular regions, increased dietary intakes could be supplied by food fortification, as well as by individual improvements in intake.
Excretion of endogenous and exogenous purine derivatives in sheep: effect of increased concentrate intake
Authors: Pérez J. F. , Balcells J. , Cebrián J. A. , Martín-Orúe S. M.
Published: June 2005

The present study examined the endogenous urinary excretion of purine derivatives (PD; allantoin, uric acid and xanthine plus hypoxanthine) in fed animals. Four Rasa Aragonesa ewes fitted with simple cannulas in the rumen and proximal duodenum were used. Animals were given a lucerne (Medicago sativa) hay diet, as sole feed (A) or supplemented, respectively, with 220 (B), 400 (C), and 550 (D) g rolled barley grain/d following a 4 × 4 random factorial design. Duodenal flow of purine bases (PB) was determined by the dual-phase marker system.15N was infused continuously into the rumen to label exogenous or microbial PB. Duodenal PB flow and urinary excretion of PD increased with digestible organic matter intake showing a constant recovery of duodenal PB. The isotope dilution of PD in urine samples confirmed the presence of an endogenous fraction, originating from tissues, that increased from 115.2 (SE 5.84) μmol/kg W0.75for the basal diet to 304.2 (SE 7.6) μmol/kg W0.75at the highest level of duodenal PB.
Effect of glucocorticoid excess on skeletal muscle and heart protein synthesis in adult and old rats
Authors: Savary Isabelle , Debras Elisabeth , Dardevet Dominique , Sornet Claire , Capitan Pierre , Prugnaud Jacques , Mirand Philippe Patureau , Grizard Jean
Published: June 2005

This study was carried out to analyse glucocorticoid-induced muscle wasting and subsequent recovery in adult (6-8 months) and old (18-24 months) rats because the increased incidence of various disease states results in hypersecretion of glucocorticoids in ageing. Adult and old rats received dexamethasone in their drinking water for 5 or 6 d and were then allowed to recover for 3 or 7 d. As dexamethasone decreased food intake, all groups were pair-fed to dexamethasonetreated old rats (i.e. the group that had the lowest food intake). At the end of the treatment, adult and old rats showed significant increases in blood glucose and plasma insulin concentrations. This increase disappeared during the recovery period. Protein synthesis of different muscles was assessed in vivo by a flooding dose of [13C]valine injected subcutaneously 50 min before slaughter. Dexamethasone induced a significant decrease in protein synthesis in fast-twitch glycolytic and oxidative glycolytic muscles (gastrocnemius, tibialis anterior, extensor digitorum longus). The treatment affected mostly ribosomal efficiency. Adult dexamethasone-treated rats showed an increase in protein synthesis compared with their pair-fed controls during the recovery period whereas old rats did not. Dexamethasone also significantly decreased protein synthesis in the predominantly oxidative soleus muscle but only in old rats, and increased protein synthesis in the heart of adult but not of old rats. Thus, in skeletal muscle, the catabolic effect of dexamethasone is maintained or amplified during ageing whereas the anabolic effect in heart is depressed. These results are consistent with muscle atrophy occurring with ageing.
A Sphingolipid Elicitor-Inducible Mitogen-Activated Protein Kinase Is Regulated by the Small GTPase OsRac1 and Heterotrimeric G-Protein in Rice
Authors: Lieberherr Damien , Thao Nguyen Phuong , Nakashima Ayako , Umemura Kenji , Kawasaki Tsutomu , Shimamoto Ko
Published: June 2005

Mitogen-activated protein kinase (MAPK) cascades are activated in plants during responses to pathogens or to pathogen-derived elicitors and mediate intracellular stress responses. Here, we show that a rice (Oryza sativa) MAPK, OsMAPK6, was posttranslationally activated in a cell culture by a sphingolipid elicitor. Suppression of OsMAPK6 expression by RNA interference resulted in a strong reduction of pathogen-induced Phe ammonia-lyase mRNA, whereas the mRNA level of another rice MAPK, OsMAPK5a, was highly increased. Silencing of a small GTPase, OsRac1, by RNA interference or loss-of-function mutation (d1) of the heterotrimeric G-protein α-subunit gene resulted in a strong reduction of the OsMAPK6 protein levels and of kinase activation by a sphingolipid elicitor. Furthermore, coimmunoprecipitation experiments with OsRac1 and OsMAPK6 proteins showed that OsMAPK6 is closely associated with the active form of OsRac1, but not with inactive forms of OsRac1. These results indicate that these two G-proteins regulate an elicitor-inducible MAPK in rice at the protein level.
Pectin Methylesterase, a Regulator of Pollen Tube Growth
Authors: Bosch Maurice , Cheung Alice Y. , Hepler Peter K.
Published: June 2005

The apical wall of growing pollen tubes must be strong enough to withstand the internal turgor pressure, but plastic enough to allow the incorporation of new membrane and cell wall material to support polarized tip growth. These essential rheological properties appear to be controlled by pectins, which constitute the principal component of the apical cell wall. Pectins are secreted as methylesters and subsequently deesterified by the enzyme pectin methylesterase (PME) in a process that exposes acidic residues. These carboxyls can be cross-linked by calcium, which structurally rigidifies the cell wall. Here, we examine the role of PME in cell elongation and the regulation of its secretion and enzymatic activity. Application of an exogenous PME induces thickening of the apical cell wall and inhibits pollen tube growth. Screening a Nicotiana tabacum pollen cDNA library yielded a pollen-specific PME, NtPPME1, containing a pre-region and a pro-region. Expression studies with green fluorescent protein fusion proteins show that the pro-region participates in the correct targeting of the mature PME. Results from in vitro growth analysis and immunolocalization studies using antipectin antibodies (JIM5 and JIM7) provide support for the idea that the pro-region acts as an intracellular inhibitor of PME activity, thereby preventing premature deesterification of pectins. In addition to providing experimental data that help resolve the significance and function of the pro-region, our results give insight into the mechanism by which PME and its pro-region regulate the cell wall dynamics of growing pollen tubes.
Comparison of Tuber Proteomes of Potato Varieties, Landraces, and Genetically Modified Lines
Authors: Lehesranta Satu J. , Davies Howard V. , Shepherd Louise V.T. , Nunan Naoise , McNicol Jim W. , Auriola Seppo , Koistinen Kaisa M. , Suomalainen Soile , Kokko Harri I. , Kärenlampi Sirpa O.
Published: June 2005

Crop improvement by genetic modification remains controversial, one of the major issues being the potential for unintended effects. Comparative safety assessment includes targeted analysis of key nutrients and antinutritional factors, but broader scale-profiling or “omics” methods could increase the chances of detecting unintended effects. Comparative assessment should consider the extent of natural variation and not simply compare genetically modified (GM) lines and parental controls. In this study, potato (Solanum tuberosum) proteome diversity has been assessed using a range of diverse non-GM germplasm. In addition, a selection of GM potato lines was compared to assess the potential for unintended differences in protein profiles. Clear qualitative and quantitative differences were found in the protein patterns of the varieties and landraces examined, with 1,077 of 1,111 protein spots analyzed showing statistically significant differences. The diploid species Solanum phureja could be clearly differentiated from tetraploid (Solanum tuberosum) genotypes. Many of the proteins apparently contributing to genotype differentiation are involved in disease and defense responses, the glycolytic pathway, and sugar metabolism or protein targeting/storage. Only nine proteins out of 730 showed significant differences between GM lines and their controls. There was much less variation between GM lines and their non-GM controls compared with that found between different varieties and landraces. A number of proteins were identified by mass spectrometry and added to a potato tuber two-dimensional protein map.
Antisense Suppression of Deoxyhypusine Synthase in Tomato Delays Fruit Softening and Alters Growth and Development
Authors: Wang Tzann-Wei , Zhang Chun-Guang , Wu Wendy , Nowack Linda M. , Madey Ewa , Thompson John E.
Published: June 2005

The effects of suppressing deoxyhypusine synthase (DHS) have been examined in tomato (Solanum lycopersicum cv UCT5). DHS mediates the first of two sequential enzymatic reactions that activate eukaryotic translation initiation factor-5A (eIF-5A) by converting a conserved Lys to the unusual amino acid, deoxyhypusine. DHS protein levels were suppressed in transgenic plants by expressing the 3′-untranslated region of tomato DHS under regulation of the constitutive cauliflower mosaic virus promoter. Fruit from the transgenic plants ripened normally, but exhibited delayed postharvest softening and senescence that correlated with suppression of DHS protein levels. Northern-blot analysis indicated that all four gene family members of tomato eIF-5A are expressed in fruit, and that three are up-regulated in parallel with enhancement of DHS mRNA as the fruit begin to senesce and soften. Transgenic plants in which DHS was more strongly suppressed were male sterile, did not produce fruit, and had larger, thicker leaves with enhanced levels of chlorophyll. The activity of PSII was 2 to 3 times higher in these transgenic leaves than in corresponding leaves of wild-type plants, and there was also enhanced deposition of starch in the stems. The data collectively indicate that suppression of DHS has pleiotropic effects on growth and development of tomato. This may, in turn, reflect the fact that there is a single DHS gene in tomato and that its cognate protein is involved in the activation of four distinct isoforms of eIF-5A.
Inhibition of de Novo Pyrimidine Synthesis in Growing Potato Tubers Leads to a Compensatory Stimulation of the Pyrimidine Salvage Pathway and a Subsequent Increase in Biosynthetic Performance
Authors: Geigenberger Peter , Regierer Babette , Nunes-Nesi Adriano , Leisse Andrea , Urbanczyk-Wochniak Ewa , Springer Franziska , van Dongen Joost T. , Kossmann Jens , Fernie Alisdair R.
Published: June 2005

Pyrimidine nucleotides are of general importance for many aspects of cell function, but their role in the regulation of biosynthetic processes is still unclear. In this study, we investigate the influence of a decreased expression of UMP synthase (UMPS), a key enzyme in the pathway of de novo pyrimidine synthesis, on biosynthetic processes in growing potato (Solanum tuberosum) tubers. Transgenic plants were generated expressing UMPS in the antisense orientation under the control of the tuber-specific patatin promoter. Lines were selected with markedly decreased expression of UMPS in the tubers. Decreased expression of UMPS restricted the use of externally supplied orotate for de novo pyrimidine synthesis in tuber tissue, whereas the uridine-salvaging pathway was stimulated. This shift in the pathways of UMP synthesis was accompanied by increased levels of tuber uridine nucleotides, increased fluxes of [14C]sucrose to starch and cell wall synthesis, and increased amounts of starch and cell wall components in the tubers, whereas there were no changes in uridine nucleotide levels in leaves. Decreased expression of UMPS in tubers led to an increase in transcript levels of carbamoylphosphate synthase, uridine kinase, and uracil phosphoribosyltransferase, the latter two encoding enzymes in the pyrimidine salvage pathways. Thus, the results show that antisense inhibition of the de novo pathway of pyrimidine synthesis leads to a compensatory stimulation of the less energy-consuming salvage pathways, probably via increased expression and activity of uridine kinase and uracil phosphoribosyltransferase. This results in increased uridine nucleotide pool levels in tubers and improved biosynthetic performance.
Towards an economy of higher education
Authors: Standish Paul
Published: June 2005

This paper draws a distinction between ways of thinking and acting, and hence of policy and practice in higher education, in terms of different kinds of economy: economies of exchange and economies of excess. Crucial features of economies of exchange are outlined and their presence in prevailing conceptions of teaching and learning is illustrated. These are contrasted with other possible forms of practice, which in turn bring to light the nature of an economy of excess. In more philosophical terms, and to expand on the picture, economies of excess are elaborated with reference, first, to the understanding of alterity in the work of Emmanuel Levinas and, second, to the idea of Dionysian intensity that is to be found in Nietzsche. In the light of critical comment on some current directions in policy and practice, the implications of these ways of thinking for the administrator, the teacher and the student in higher education are explored.
‘Dear More or Less…’
Authors: Blastland Michael
Published: June 2005

More or Less, BBC Radio 4′s programme devoted to the “powerful, sometimes beautiful, often abused but ever ubiquitous world of numbers”, has now been running for 3 years and returns to the airwaves on June 16th. Producer Michael Blastland and presenter Andrew Dilnot look back over the topics that provoked the greatest audience reaction.
PGE1analog alprostadil induces VEGF and eNOS expression in endothelial cells
Authors: Haider Dominik G. , Bucek Robert A. , Giurgea Aura G. , Maurer Gerald , Glogar Helmut , Minar Erich , Wolzt Michael , Mehrabi Mohammad R. , Baghestanian Mehrdad
Published: June 2005

Endothelial nitric oxide synthase (eNOS), VEGF, and hypoxia-inducible factor 1-α (HIF-1α) are important regulators of endothelial function, which plays a role in the pathophysiology of heart failure (HF). PGE1analog treatment in patients with HF elicits beneficial hemodynamic effects, but the precise mechanisms have not been investigated. We have investigated the effects of the PGE1analog alprostadil on eNOS, VEGF, and HIF-1α expression in human umbilical vein endothelial cells (HUVEC) using RT-PCR and immunoblotting under normoxic and hypoxic conditions. In addition, we studied protein expression by immunohistochemical staining in explanted hearts from patients with end-stage HF, treated or untreated with systemic alprostadil. Alprostadil causes an upregulation of eNOS and VEGF protein and mRNA expression in HUVEC and decreases HIF-1α. Hypoxia potently increased eNOS, VEGF, and HIF-1α synthesis. The alprostadil-induced upregulation of eNOS and VEGF was prevented by inhibition of MAPKs with PD-98056 or U-0126. Consistently, the expression of eNOS and VEGF was increased, and HIF-1α was reduced in failing hearts treated with alprostadil. The potent effects of alprostadil on endothelial VEGF and eNOS synthesis may be useful for patients with HF where endothelial dysfunction is involved in the disease process.