bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel dietary strategy for overcoming the antinutritional effects of soyabean whey of high agglutinin content
Authors: Pusztai A. , Grant G. , Bardocz S. , Gelencser E. , Hajos GY.
Published: June 2005

A diet-switching experiment, which aimed to improve the utilization of soyabean whey was carried out for 61 d with young rats. Feeding was arranged in such a way that after a few days on the soyabean diet, the rats were switched to a high-quality lactalbumin diet for a short period, after whicb the cycle was repeated several times. The weights of the rats at the end of the soyabean phases were significantly less than those of animals pair-fed on a high-quality diet throughout. However, the test group regained the weight loss after switching to the lactalbumin diet. After three cycles there were no significant differences between the weights of the test rats fed on a poor soyabean diet for over a third of the experiment and those fed on the lactalbumin diet throughout. Feed conversion was always significantly higher with test rats in the lactalbumin period than with continually pair-fed controls. Similarly, faecal N losses were significantly higher for test rats in the soyabean phase, but these differences disappeared after switching to the lactalbumin diet. At the end of the experiment there were no significant differences in body protein or lipids between the groups although the pancreas was significantly heavier while the liver was lighter in soyabean-fed rats. The high destruction of trypsin inhibitors in the gut suggests that they probably had little effect on protein digestion in the gut. In contrast, as selective depletion of the agglutinin from soyabean whey removed the nutritional benefit in the lactalbumin part of the cycle, the improved feed conversion in this period must have been the result mainly of the survival and functionality of soyabean agglutinin and the benefits due to the hyperplastic growth and faster renewal of the gut surface it induced. As processing is unnecessary, this novel method is cheap and can be easily adapted for the use of soyabean whey, regarded as a waste product.
Immunocompetence in relation to a heat-processed diet (Maillard reaction) in weanling rats
Authors: Varela Pilar , Arce María Del Mar , Marcos Ascensión , Castrillón Ana María
Published: June 2005

Diets containing unheated casein (CD; control) or a casein-glucose mixture (CGD) previously heated at 140° for 2 h were fed to two groups of young rats for 21 d. Differences in body weight, feed consumption, thymus and spleen growth, protein metabolism andin vivoimmune response were then determined. For this last experiment, animals were inoculated with sheep erythrocytes (SRBC) on day 15 to provide an immunological challenge. No changes were seen in body weight, feed consumption or feed conversion ratios. Neither were significant differences found in spleen weight, protein content, DNA content, DNase (EC3.1.4.6) activity or lymphocyte count, suggesting that spleen cell growth remained similar in all the animals studied. The CGD induced marked increases in thymus DNA content whilst the protein:DNA ratio became lower. Spleen RNA content was similar in all rats, but thymus RNA content was 29% lower in the CGD group, although this difference did not reach statistical significance. This fact might be a consequence of the low RNase (EC2.7.7.16) activity and RNase:RNA ratios in the thymus glands of CGD-fed animals. Further, the number of splenic plasma cells secreting anti-SRBC antibodies (direct plaque-forming cells) was significantly decreased in the same group. It might be concluded that both diets are adequate for rat growth and that the differences observed in the thymus of CGD-fed rats may be directed towards preserving tissue function. Nevertheless, the CGD did cause immunological disturbances affecting the humoral immune response.
Study of magnesium bioavailability using stable isotopes and the inductively-coupled plasma mass spectrometry technique in the rat: single and double labelling approaches
Authors: Coudray Charles , Pepin Denise , Tressol Jean Claude , Bellanger Jacques , Rayssiguier Yves
Published: June 2005

The present work aimed to investigate the feasibility of using stable isotopes and inductively-coupled plasma mass spectrometry (ICP/MS) to study Mg absorption in rats. Male Wistar rats, aged 7 weeks and weighing 180g, were used. They were fed on a semi-purified diet containing 1070mg Mg/kg, and had free access to feed and distilled water. In the first experiment, after a 16d adaptation period, two doses of enriched 25Mg (6 and 12mg) were administered by oral intubation, faeces and urine were collected daily and blood was sampled. Isotope ratios were determined by ICP/;MS. ‘True’ absorption values, using the faecal isotope data, were 0.63 and 0.56 in rats receiving 6 and 12mg 25Mg respectively, while apparent absorption was 0.50 for two successive periods of metabolic balance studies. Moreover, the oral isotope administration resulted in a measurable isotopic enrichment in plasma within hours which was still detectable on the third day following the isotope administration. In the second experiment, investigating the double labelling technique, similar rats were dosed Simultaneously with 5mg 26Mg orally (premixed with diet) and 0.29mg 25Mg intravenously. The calculated Mg true absorption values were very similar when calculated from blood or urine data (0.38) but were lower than that obtained from faecal data (0.50). The possible causes of such an unexpected difference and limits of the double labelling technique for Mg absorption are discussed here. Together these results indicate that although 25Mg and 26Mg isotopes have high natural abundance, the described methodology permits meaningful investigations of Mg bioavailability and metabolism
Eating frequency: methodological and dietary aspects
Authors: Gatenby Susan J.
Published: June 2005

It is commonly stated that ‘snack’ foods provide ‘empty calories’ and, therefore elevate energy intake whist providing insignificant quantities of other nutrients. The data presented in the present review suggest that foods which contribute to the pattern of ‘snacking’ contribute significantly to the nutrient quality of the diet. Those who ‘snack’ frequently tend to eat more food in general. Part of the difficulty in identifying the nutritional implications of ‘snacking’ is related to the definitions of ‘meals’ and ‘snacks’ and subsequent categorization of individual patterns. The physiological definitions typically relating to energy content or the time of eating do not necessarily coincide with colloquial, cultural or individual perceptions of what constitutes a ‘meal’ or ‘snack’. Clearly, a more consistent approach would facilitate interpretation of the literature and enable more effective health education messages about ‘snacking’ to be delivered.
Socio-cultural determinants of meal size and frequency
Authors: De Castro John M.
Published: June 2005

Total energy intake and the frequency and size of meals are profoundly influenced by the socio-cultural context in which it occurs. Simply eating with one other person increases the average amount ingested in meals by 44% and with more people present the average meal size grows even larger. The impact of social facilitation of energy intake on the individual appears to result from genetic effects both on the individuals' sensitivity to the presence of other people and also on the number of other people an individual tends to eat with. Culture markedly affects the choice of foods in the diet and the pattern of meals over the day. However, many of the social, psychological and physical variables that influence intake are similar across cultures.
Meal frequency and energy balance
Authors: Bellisle France , McDevitt Regina , Prentice Andrew M.
Published: June 2005

Several epidemiological studies have observed an inverse relationship between people's habitual frequency of eating and body weight, leading to the suggestion that a ‘nibbling’ meal pattern may help in the avoidance of obesity. A review of all pertinent studies shows that, although many fail to find any significant relationship, the relationship is consistently inverse in those that do observe a relationship. However, this finding is highly vulnerable to the probable confounding effects of post hoc changes in dietary patterns as a consequence of weight gain and to dietary under-reporting which undoubtedly invalidates some of the studies. We conclude that the epidemiological evidence is at best very weak, and almost certainly represents an artefact. A detailed review of the possible mechanistic explanations for a metabolic advantage of nibbling meal patterns failed to reveal significant benefits in respect of energy expenditure. Although some short-term studies suggest that the thermic effect of feeding is higher when an isoenergetic test load is divided into multiple small meals, other studies refute this, and most are neutral. More importantly, studies using whole-body calorimetry and doubly-labelled water to assess total 24h energy expenditure find no difference between nibbling and gorging. Finally, with the exception of a single study, there is no evidence that weight loss on hypoenergetic regimens is altered by meal frequency. We conclude that any effects of meal pattern on the regulation of body weight are likely to be mediated through effects on the food intake side of the energy balance equation.
Carbohydrate tolerance and food frequency
Authors: Jenkins David J. A.
Published: June 2005

Dietary and pharmacological approaches to slowing the rate of glucose absorption and blunting the insulin response show promise in the treatment of diabetes and hyperlipidaemia. These approaches include dietary fibre, low-glycaemic-index foods and gastrointestinal digestive enzyme inhibitors. One common feature is that they spread the nutrient load over time. A potentially simpler approach is to take more frequent smaller meals over a longer period of the day. Early studies suggested that frequent glucose and insulin administration to diabetic patients improved diabetes control. More recent acute studies of one test meal or 1 d blood metabolite profiles have identified a significant economy in insulin secretion when glucose is sipped or when meal frequency is increased in both diabetic or non-diabetic subjects. In diabetic subjects improvement in mean blood glucose levels has also been reported. However, despite the demonstration of an alteration in response over time in glucose tolerance in healthy volunteers, no longer-term improvement in glycaemic control was reported in the only study in diabetes to examine a change from three to nine meals daily over a 1- month period. The disparity between longer-term and acute studies requires further investigation. At present, although this nutritional approach holds considerable theoretical promise, specific advice is premature.
Meal frequency and plasma lipids and lipoproteins
Authors: Mann Jim
Published: June 2005

Epidemiological data suggesting benefits of increased meal frequency on CHD risk and lipid and lipoprotein levels may be flawed because of biases associated with the method of data collection. In normolipidaemic individuals increasing meal frequency from three to six or more meals daily over a period of several weeks appears to be associated with reduced levels of total and LDL-cholesterol, possibly due to reduced cholesterol synthesis or enhancement of reverse cholesterol transport. However, in non-obese individuals with polygenic hyperlipidaemia and non-insulin-dependent diabetes, altered meal frequency does not appear to confer similar benefits. The reasons for the different responses in these groups of subjects is not clear. The reported effects of altered meal frequency on diurnal levels of triacylglycerols and fatty acids are more variable, with benefits being reported principally in association with meal frequencies exceeding those which might be translated into practical recommendations. Present data preclude recommendations concerning meal frequency on the basis of effects on lipids and lipoproteins. Even in healthy individuals amongst whom benefits have been observed, the periods of observation have been relatively short and it is not known whether adaptation occurs. Further research should focus on longer-term studies in healthy individuals as well as hyperinsulinaemic and diabetic subjects. For those individuals choosing to have a large number of small meals each day, it is relevant to emphasize that no untoward effects of increased meal frequency on lipids or lipoproteins have been demonstrated.
Effect of meal frequency and timing on physical performance
Authors: Hawley John A. , Burke Louise M.
Published: June 2005

Two areas of sports nutrition in which the periodicity of eating has been studied relate to: (1) the habitually high energy intakes of many athletes, and (2) the optimization of carbohydrate(CHO) availability to enhance performance. The present paper examines how the timing and frequency of food and fluid intake can assist the athlete and physically-active person to improve their exercise performance in these areas. Frequent eating occasions provide a practical strategy allowing athletes to increase energy intake while concomitantly reducing the gastric discomfort of infrequent large meals. The optimization of CHO stores is a special challenge for athletes undertaking prolonged training or competition sessions. This is a cyclical process with post-exercise CHO ingestion promoting muscle and liver glycogen re-synthesis; pre-exercise feedings being practised to optimize substrate availability and feedings during exercise providing a readily-available source of exogenous fuel as endogenous stores become depleted. The timing and frequency of CHO intake at these various stages are crucial determinants for optimizing fuel availability to enhance exercise capacity.
Psychological effects of snacks and altered meal frequency
Authors: Kanarek Robin
Published: June 2005

Over the past two decades, substantial research has been conducted to investigate the idea that alterations in short-term nutritional intake play a role in influencing cognitive behaviour and mood. A portion of this research has examined specifically the effect of meal intake on the performance of mental tasks and subjective feelings of mood. Results of this research indicate that a number of variables including the timing and nutritional composition of the meal, nutritional status, habitual patterns of feeding behaviour, beliefs about food, and the nature of the mental tasks, can influence the effects of meals on cognitive behaviour. For example, studies have demonstrated that breakfast intake generally is associated with an improvement in cognitive performance later in the morning, while lunch intake is associated with an impairment in mid-afternoon performance on mental tasks and more negative reports of mood. Intake of nutrients late in the afternoon appears to have a positive effect on subsequent performance on tasks involving sustained attention or memory. Although research has provided insights into the role of meal intake on cognitive behaviour and mood, there are a number of factors which remain to be studied. These include the interaction of age, gender, activity level, meal composition, personality factors, stress with the effects of meals on cognitive behaviour. Additionally, more work is needed on the time-course of short-term nutrient effects, and the effects of chronic changes in meal intake on behaviour.
Sugar, alternative sweeteners and meal frequency in relation to caries prevention: new perspectives
Authors: Kandelman Daniel
Published: June 2005

In the last 20 years, mainly due to optimum fluoride exposure, and practice of good oral hygiene procedures, an important reduction in caries has been observed, despite the fact that sugar consumption was maintained and/or was increasing during the same lapse of time. A sugar-caries relationship cannot be established in most of the industrialized countries and the dietary factor is not as preponderant in the caries process as it used to be two decades ago. The factors which seem to contribute the most significantly to the cariogenicity of the diet are the frequency of carbohydrate ingestion and eating patterns. The relative cariogenicity of food is not correlated with the amount of carbohydrate it contains. Even if sucrose remains the most important sugar consumed in sweets, beverages and confectionery products, all fermentable-carbohydrate foods can be involved in the caries process. The use of chewing gum and other xylitol-containing products have resulted in defined reduction in caries and represent interesting alternatives for high-caries-risk populations. Caries risk and oral health assessments as well as the evaluation of oral hygiene procedures and fluoride exposure should become essential tools in dietary counselling. People who receive optimum fluoride exposure and follow regular oral hygiene measures can safely use dietary carbohydrates, preferably during meals and two to three times daily in snacks or drinks.
Effect of orally administered glutathione on glutathione levels in some organs of rats: role of specific transporters
Authors: Favilli Fabio , Marraccini Patrizia , Iantomasi Teresa , Vincenzini Maria T.
Published: June 2005

The present study reports data on absorption of orally administered glutathione (GSH) in rat jejunum and in other organs, and the possible role of specific transport systems of GSH and γ-glutamyltranspeptidase (EC2.3.2.1; γ-GT) activity. GSH levels were measured simultaneously in various organs after oral GSH administration to untreated rats and rats treated with L-buthionine sulfoximine (BSO) or acivicin (AT125). BSO selectively inhibits GSH intracellular synthesis and AT125is a specific inhibitor of γ-GT activity. GSH levels were also measured after oral administration of an equivalent amount of the constituent amino acids of GSH to untreated and BSO-treated rats. Significant increases in GSH levels were found in jejunum, lung, heart, liver and brain after oral GSH administration to untreated rats. GSH increases were also obtained in all organs, except liver, when GSH was administered to rats previously GHS-depleted by treatment with BSO. The analysis of all results allowed us to distinguish between the increase in GSH intracellular levels due to intact GSH uptake by specific transporters, and that due to GSH degradation by γ-GT activity and subsequent absorption of degradation products with intracellular resynthesis of GSH; both these mechanisms seemed to be involved in increasing GSH content in heart after oral GSH administration. Jejunum, lung and brain took up GSH mostly intact, by specific transport systems, while in liver GSH uptake occurred only by its breakdown by γ-GT activity followed by intracellular resynthesis.
Compared effects of three oligosaccharides on metabolism of intestinal microflora in rats inoculated with a human faecal flora
Authors: Djouzi Zakia , Andlueux Claude
Published: June 2005

Using germ-free rats inoculated with a human faecal flora (gnotobiotic rats), the effects of three oligosaccharides (β-fructo-oligosaccharides (FOS), β-galacto-oligosaccharides (TOS) and α-gluco-oligosaccharides (GOS)) on intestinal bacterial metabolism were compared. The animals were fed on either a control diet or diets containing 4Og/kg of GOS, FOS or TOS. FOS and TOS were the preferred growth substrates for Bifidobacteria which increased in number by 2 log values in faeces of rats when compared with rats fed on GOS or control diets. Ingestion of TOS specifically induced hydrolysis of the substrate, and did not modify the activity of any other enzymes measured in the caecum. GOS led to a non-specific enzymic induction of β-galactosidase (EC 3.2.1.23), β-glucosidase (EC 3.2.1.21) and α-glucosidase (EC 3.2.1.20) activities whereas β-glucuronidase (EC 3.2.1.31) was lowered. Compared with the control group, FOS and TOS diets led to a significant increase in H2and CH4excretion; the GOS diet increased only CH4. Analysis of caecal contents revealed a decrease in pH for all diets compared with controls. Total short-chain fatty acid (SCFA) concentration increased significantly in all groups, but the SCFA profile differed between treatment groups. It was concluded that the three oligosaccharides studied had different effects which may be linked to their chemical structure. Some of these effects may be beneficial to human health
Pancreatic and extra-pancreatic effects of the traditional anti-diabetic plant,Medicago sativa(lucerne)
Authors: Gray Alison M , Flatt Peter R
Published: June 2005

Medicago sativa(lucerne) is used as a traditional plant treatment of diabetes. In the present study, administration of lucerne in the diet (62·5 g/kg) and drinking water (2·5 g/l) reduced the hyperglycaemia of streptozotocin-diabetic mice. An aqueous extract of lucerne (1 mg/ml) stimulated 2-deoxy-glucose transport (1·8-fold), glucose oxidation (1·7-fold) and incorporation of glucose into glycogen (l·6-fold) in mouse abdominal muscle. In acute 20 min tests, 0·25–1 mg/ml aqueous extract of lucerne evoked a stepwise 2·5–6·3-fold stimulation of insulin secretion from the BRIN-BD11 pancreatic B-cell line. This effect was abolished by 0·5 mM-diazoxide, and prior exposure to extract did not affect subsequent stimulation of insulin secretion by 10 mM-L-alanine, thereby negating a detrimental effect on cell viability. The effect of extract was potentiated by 16·7 mM-glucose and by 1 mM-3-isobutyl-1-methylxanthine. L-Alanine (10 mM) and a depolarizing concentration of KCI (25 mM) did not augment the insulin-releasing activity of lucerne. Activity of the extract was found to be heat stable and largely acetone insoluble, and was enhanced by exposure to acid and alkali (0·1 M-HCI and NaOH) but decreased 25% with dialysis to remove components with molecular mass <2000 Da. Sequential extraction with solvents revealed insulin-releasing activity in both methanol and water fractions indicating a cumulative effect of more than one extract constituent. The results demonstrate the presence of antihyperglycaemic, insulin-releasing and insulin-like activity in the traditional antidiabetic plant,Medicago sativu.
Effect of food products on endogenous generation of n−nitrosamines in rats
Authors: Atanasova-Goranova V. K. , Dimova P. I. , Pevicharova G. T.
Published: June 2005

An experiment was conducted to study the efficacy of two tomato pastes and aronia nectar (fruit juice + pulp from the black chokeberry, Aronia melanocarpa Elliot) as inhibitors of nitrosamine production in cancer prophylaxis programmes. White male rats of the Wistar strain were employed in an acute trial. Aminopyrin + sodium nitrite (APSN) were used as precursors for generation of endogenous nitrosamine. The animals were allocated to different dietary groups and fed by intubation with APSN or APSN + food products. Introduction of tomato paste (TP), high-β-carotene tomato paste (HCTP) and aronia nectar (AN) as inhibitors of n−nitrosamine formation exerted a positive effect on blood and liver variables which was demonstrated by decreased concentrations of glutamic-oxaloacetic transaminase (EC 2.6.1.1), glutamic-pyruvic transaminase (EC 2.6.1.2) and uric acid in serum and lipid content in hepatocytes. Animals treated with APSN developed dystrophic changes in liver such as centrolobular necrosis, intense exangia, and enlarged cells with two, often large, pyknotic nuclei, while the structure of livers of rats fed with TP, HCTP or AN was well protected and almost normal. TP had a particularly beneficial effect on serum total protein and albumin concentrations as had AN on the urea value. The inhibitory effect of th food products used is explained by their chemical nature including pH, ascorbic index (ascorbate:nitrate), lycopene and β-carotene contents.
The prediction of total body water from bioelectrical impedance in patients with anorexia nervosa
Authors: Scalfi L. , Bedogni G. , Marra M. , Di Biase G. , Caldara A. , Severi S. , Contaldo F. , Battistini N.
Published: June 2005

Total body water (TBW) was measured by deuterium oxide (D2O) dilution and predicted from bioelectrical impedance (Z) in nineteen anorexic and twenty-seven control women. The equation of Kushneret al.(1992) based on the impedance index (ZI = height2/Z) gave biases of 0.9 (sd2.5) and 0.8 (sd2.5) litres in controls and patients respectively (NS, ANOVA). The ZI-based equation of Deurenberget al.(1993) gave biases of 1.5 (sd2.4) litres (NS) and 3.0 (sd2.1) litres (P<0.001) in controls and patients respectively. Despite the fact that weight was the most powerful predictor of TBW on the study sample (n46,r20.90,P< 0.0001,seof the estimate 1.6 litres, CV 5.7%), the formulas of Segalet al.(1991) and Kushneret al.(1992) based on the association of weight and ZI gave an inaccurate prediction of TBW in both control and anorexic subjects, with a bias ranging from -3.2 (sd2.4) to 2.9 (sd2.1) litres (P≤0.001). Population-specific formulas based on ZI (n46) gave a more accurate prediction of TBW by bioelectrical impedance analysis on the study subjects, with biases of -0.1 (sd1.8) and 0.5 (sd1.7) litres in controls and patients respectively (NS). However, the individual bias was sometimes high. It is concluded that bioelectrical impedance analysis can be used to predict TBW in anorexic women at a population level, but the predictions are less good than those based on body weight alone.
Non-milk extrinsic sugars in the diets of pre-school children: association with intakes of micronutrients, energy, fat and NSP
Authors: Gibson Sigrid A.
Published: June 2005

Concern has been expressed that high dietary concentrations of non-milk extrinsic sugars (NMES) may potentially compromise nutrient intakes in population groups with low energy intakes (Department of Health, 1991). The objective of the present study was to examine data from the National Diet and Nutrition Survey of Children Aged 1.5 to 4.5 years (Gregory et al. 1995) for evidence of an inverse association between energy from NMES and micronutrient intakes, and if possible to quantify a level of NMES-energy at which micronutrient intakes may, theoretically, be compromised. Energy and nutrient intakes were compared across quintiles of NMES-energy for boys (n 848) and girls (n 827). As the concentration of NMES increased, energy intake rose (in boys only) while percentage energy from fat fell from 40 to 32 % across quintiles 1 to 5. Intakes of most micronutrients also fell, while intakes of vitamin C rose. Mean intakes of most micronutrients (Ca, thiamin, riboflavin, niacin, folate and vitamin C) were adequate in comparison with dietary reference values. However, intakes of Fe, Zn and vitamin D were low at all levels of NMES-energy and fell below the estimated average requirement for Fe and Zn for NMES concentrations exceeding 24 % of energy. Lower intakes of milk, meat, bread and vegetables, and higher intakes of fruit juice largely explain the observed trends in micronutrient intake. It is concluded that the inverse association of NMES with micronutrient intakes is of most significance for the 20 % of children with diets highest in NMES. However, further work is required to establish whether the associations observed have biological significance with regard to micronutrient status.
Dynamic aspects of oxygen consumption and carbon dioxide production in swine
Authors: Van Milgen J. , Noblet J. , Dubois S. , Bernier J.-F.
Published: June 2005

A model is proposed that allows study of the short-term dynamics of gas exchanges (and heat production) in large open-circuit respiration chambers. The model describes changes in [O2] and [CO2] in the respiration chamber by a series of differential equations based on animal metabolism and physical characteristics of gas exchange. The model structure was similar for O2and CO2, although model parameters differed. A constant level of O2consumption (and CO2production) was assumed for resting animals which was different for fed and fasted animals. The adaptation from a fed to a fasting state was described as a first-order process. Physical activity (standing or sitting) was recorded and was included in the model as a constant. Thermic effect of feed comprised the O2consumption and CO2production related to several relatively rapidly occurring processes after ingestion of a meal (e.g. ingestion, digestion or absorption). In the model, these processes were pooled into a single phenomenon. Model parameters were obtained statistically by comparing model predictions (based on the numerically integrated differential equations) with the observed [O2] and [CO2]. The model was evaluated by studying gas exchanges in growing pigs that were fasted for 31 h and re-fed a single meal thereafter. The model fitted the data well over the 47 h measurement range. Traditional methods in which heat production is calculated suffer from noisy data when the interval between observations becomes too short. The proposed method circumvents this by modelling the observed concentration of gases in the respiration chamber rather than the calculated heat production.
The effects of acute and chronic protein depletion and accretion on plasma concentrations of insulin-like growth factor-1, fibronectin and total protein for ruminants nourished by intragastric infusion of nutrients
Authors: Liu S. M. , Macleod N. A. , Luo Q. J. , Chen X. B. , Kyle D. J. , Nicol P. , Harbron C. G. , Ørskov E. R.
Published: June 2005

The relationships of N input or protein status and the concentrations of serum insulin-like growth factor-1 (IGF-1), plasma fibronectin (FN) and total protein (TP) were examined in three experiments with steers and sheep nourished by intragastric infusion of nutrients. In Expt 1, three steers (340 kg live weight) were infused with three levels of volatile fatty acids (0, 300 and 600 kJ/kg metabolic weight (W0.75) per d) and six levels of casein (0, 200, 400, 650, 1500 and 2500 mg N/kg W0.75per d). Each N treatment was imposed for 5 d. In Expts 2 and 3, five groups of sheep (about 35 kg live weight) were infused with casein at 500 mg N/kg W0.75per d for 2 weeks followed by 1500, 500 or 50 mg N/kg W0.75per d in Expt 2, and in Expt 3, with 100 mg N/kg W0.75per d for 6 weeks or 10 mg N/kg W0.75per d for 4 weeks. Non-protein energy was maintained constant at 500 kJ/kg W0.75per d throughout. Daily N balance and total body N content at the end were measured, and protein status was defined as a percentage of cumulative N accretion or depletion in relation to the total body N content at maintenance. It was found that IGF-1 and FN responded rapidly and substantially to altered N input, and that when daily N input was maintained constantly at sub-maintenance, their continuous declines were related closely to progressive protein depletion in the sheep. Plasma TP concentration was independent of N input when N input was altered acutely in the steers, but declined significantly and gradually with severe, chronic body protein depletion in the sheep. Plasma content of TP in the sheep however reduced acutely with a reduction in N input. Plasma volume fell substantially over the first 2 weeks of protein depletion, compensating for the declines in TP content and maintaining TP concentration plateau. The possible implications of the changes in TP concentration and content (concentration x volume) to body protein loss in sheep are discussed.
Influence of dietary protein and fat on serum lipids and metabolism of essential fatty acids in rats
Authors: Ratnayake W. M. Nimal , Sarwar Ghulam , Laffey Patrick
Published: June 2005

A 120 d feeding study with adult rats was conducted to evaluate the influence of two protein sources (casein and gelatin), two protein levels (50 and 300g/kg diet) and two fat levels (50 and 150g/kg diet) on serum lipids (total cholesterol, HDL-cholesterol and triacylglycerols) and liver polyunsaturated fatty acid levels. In general, the concentrations of serum triacylglycerols and total cholesterol and liver phospholipid levels of arachidonic acid (AA) and docosahexaenoic acid (DHA) were higher in rats fed on casein diets compared with those fed on the gelatin diets. These effects were more pronounced in rats fed on the high-casein (300 g/kg)-high-fat (150g/kg) diet. Gelatin was hypocholesterolaemic and also suppressed the liver phospholipid levels of AA and DHA (reported for the first time). The difference in the amino acid composition between casein and gelatin may be responsible for the observed effects. Casein contains higher levels of glutamic acid, methionine, phenylalanine and tyrosine, while gelatin contains higher levels of arginine, glycine and hydroxyproline. It is suggested that a protein source which increases serum cholesterol may also increase the concentrations of AA and DHA in rat tissues.
Modulation of cholestan-3β,5α,6β-triol toxicity by butylated hydroxytoluene, α-tocopherol and β-carotene in newborn rat kidney cellsin vitro
Authors: Wilson Alison M. , Sisk Ruth M. , O'Brien Nora M.
Published: June 2005

Cholesterol oxidation products (COP) have been reported to influence vital cellular processes such as cell growth, cell proliferation, membrane function andde novosterol biosynthesis. The objectives of the present study were: (1) to develop anin vitromodel using newborn rat kidney (NRK) cells to investigate the actions of COP; (2) to investigate the effect of COP on cell viability, endogenous antioxidant enzymes activities, i.e. superoxide dismutase (EC1.15.1.1; SOD) and catalase (EC1.11.1.6; CAT), and the extent of lipid peroxidation in this model; (3) to determine whether the addition of 100–1000 nm-α-tocopherol, β-carotene or butylated hydroxytoluene (BHT) could protect against COP-induced cytotoxicity. NRK cells were cultured in the presence of various concentrations (5–50 μM) of cholesterol or cholestan-3β,5α,6β-triol (cholestantriol) for a period of 24 h. Cholesterol over the range 5–50 μM did not induce cytotoxicity as indicated by the neutral-red-uptake assay or the lactate dehydrogenase (EC1.1.1.27)-release assay. However, cell viability was compromised by the addition of > 10 μM-cholestantriol (P< 0.05). The addition of β-carotene (100–1000 nM) did not increase cell viability significantly in cholestantriol-supplemented cells. However, the addition of α-tocopherol (1000 nM) and BHT (1000 nM) significantly increased percentage cell viability above that of the cholestantriol-supplemented cells but not back to control levels. SOD and CAT activities in NRK cells significantly decreased (P< 0.05) following incubation with cholestantriol. The addition of > 750 nM-α-tocopherol, β-carotene or BHT returned SOD and CAT activities to that of the control. Lipid peroxidation was significantly induced (P< 0.05) in the presence of cholestantriol. Supplementation of the cells with α-tocopherol (250, 500 or 1000 nM) or BHT (750 or 1000 nM) resulted in a reduction in the extent of lipid peroxidation (P< 0.05). The addition of β-carotene over the concentration range of 250–1000 nM did not reduce lipid peroxidation significantly compared with cells exposed to cholestantriol alone. These findings suggest that addition of exogenous antioxidants may be beneficial in the prevention of COP-induced toxicityin vitro.
Effect of selenium deficiency on hepatic lipid and lipoprotein metabolism in the rat
Authors: Nassir F. , Moundras C. , Bayle D. , Sérougne C. , Gueux E. , Rock E. , Rayssiguier Y. , Mazur A.
Published: June 2005

Since experimental Se deficiency results in a significant increase in plasma cholesterol concentration the present investigation was undertaken to assess further the influence of this deficiency on the expression of proteins involved in hepatic lipid metabolism. Se deficiency was induced by feeding weanling male Wistar rats on a deficient diet for 6 weeks. Hypercholesterolaemia associated with Se deficiency was related to increased 3-hydroxy-3-methylglutaryl-coA (HMG-CoA) reductase (EC1.1.1.34) activity in liver microsomes as compared with control animals. Hepatic lipoprotein receptor levels (LDL-receptor and HDL-binding proteins, HB1 and HB2) were not significantly affected by Se deficiency, as assessed by immunoblotting. Plasma triacylglycerol concentrations tended to decrease in Se-deficient rats in concert with their reduced post-Triton secretion. There was no significant effect of Se deficiency on the hepatic synthesis of apolipoproteins. These results point to the need for further investigations into the mechanism related to the increased activity of HMG-CoA reductase and the enhanced cholesterogenesis in the liver of Se-deficient rats likely to result from this.

Selenium: Cholesterol: Triacylglycerol: HMG-CoA reductase
Clarification of the link between polyunsaturated fatty acids andHelicobacter pylori-associated duodenal ulcer disease: a dietary intervention study
Authors: Duggan A. E. , Atherton J. C. , Cockayne A. , Balsitis M. , Evison S. , Hale T. , Hawkey C. J. , Spiller R. C.
Published: June 2005

Epidemiological evidence has suggested that the declining prevalence of duodenal ulcer disease may be attributable to rising consumption of polyunsaturated fatty acids, a hypothesis supported byin vitroevidence of toxicity of such substances toHelicobacter pylori.The objective of the present study was to establish whether this association is causal. Forty patients with proven infection withH. pyloriand endoscopic evidence of past or present duodenal ulcer disease were randomized to receive either polyunsaturated fatty acids (PUFA group), in the form of capsules and margarine, or a placebo (control). Both groups received concurrent H2antagonist therapy. Efficacy of therapy was determined endoscopically by assessment of ulcer healing whileH. pyloristatus was determined by antral biopsy, urease (EC3.5.1.5) culture and histological assessment of the severity ofH. pyloriinfection. Antral levels of prostaglandin E2(PGE2) and leukotriene B4(LTB4) were quantified. Compliance was monitored. Before treatment, both groups were comparable for severity ofH. pyloriinfection, smoking status and levels of LTB4and PGE2. Despite a significant difference in consumption of linoleic acid (19.9 (se) 1.6) g for PUFA group ν. 6.7 (se0.8) g for controls (P< 0.01) and linolenic acid (2.6 (se) 0.2) g ν. 0.6 (se0.03) g (P< 0.01) there was no significant change in either the severity ofH. pyloriinfection or prostaglandin levels in either group at 6 weeks. Consumption of a considerable amount of PUFA does not inhibit the colonization of the stomach byH. pylorinor does this alter the inflammatory changes characteristic ofH. pylorigastritis. We conclude that the association between duodenal ulceration and a low level of dietary PUFA is likely to be spurious, probably reflecting the effect of confounding factors such as affluence, social class or smoking.
Antioxidant status and lipid peroxidation in diabetic pregnancy
Authors: Bates J. H. , Young I. S. , Galway L. , Traub A. I. , Hadden D. R.
Published: June 2005

Pregnancy in insulin-dependent diabetes mellitus is associated with a greater incidence of fetal abnormality. Animal studies suggest that increased free-radical production and antioxidant depletion may contribute to this risk. The aim of the present study was, therefore, to assess nutritional antioxidant status and lipid peroxidation in diabetic mothers in comparison with a control group. A 7 d dietary history and a food-frequency questionnaire were performed and venous blood collected for biochemical analyses from thirty-eight diabetic mothers and matched control subjects before 12 weeks gestation. Protein intake was significantly greater in diabetic patients (81.4 (se14.8) ν. 72.7 (se15.8) g/d,P= 0.015), while total sugar intake was less (79.5 (se13.2) ν. 104.8 (se28.8) g/d,P< 0.001). There were no significant differences in the intake of the major antioxidant vitamins (retinol, vitamin C or vitamin E) or β-carotene. However, intakes of a number of other micronutrients (including Se, Zn, Mg, Mn, riboflavin, thiamin, niacin and folate) were greater in diabetic patients. Among the nutritional chain-breaking antioxidants, serum levels of α-tocopherol (21.6 (se5.7) ν. 17.3 (se4.7) μmol/1,P= 0.0013), β-carotene (0.27 (se0.18) ν. 0.14 (se0.11) μmol/1,P= 0.003) and lycopene (0.23 (se0.17) ν. 0.16 (se0.13) μmol/1,P= 0.03) were greater in diabetic patients. There was no evidence of greater lipid peroxidation in diabetic patients, and total antioxidant capacity was similar in the two groups. Overall, these results indicate that nutritional antioxidant status is better in this group of diabetic mothers than in control pregnant non-diabetic subjects attending the same maternity hospital.
Effect of source of starch on net portal flux of glucose, lactate, volatile fatty acids and amino acids in the pig
Authors: Van Der Meulen J. , Bakker J. G. M. , Smits B. , De Visser H.
Published: June 2005

The ileal digestibilities of maize starch and native pea starch do not differ. However maize starch is digested faster than pea starch and the ileal amino acid digestibility of a diet containing pea starch is lower. In the present study, the net portal fluxes of glucose, lactate, volatile fatty acids (VFA) and amino acids were measured for diets including 650 g maize starch or pea starch/kg. The diets were fed at a level 870 kJ digestible energy/kg0.75twice daily (06.00 and 18.00 hours) to four female pigs in a crossover design. Portal vein blood flow did not differ between maize and pea starches (1620 and 1484 ml/min respectively;sed100;P= 0.23). For maize starch portal glucose flux was significantly higher during the first 6 h after feeding, was not different 8 h after feeding and was significantly lower thereafter. Net portal glucose flux was higher for maize starch than for pea starch (1759 and 1265 mmol/12 h respectively;sed182;P= 0.054). Net portal lactate flux was not significantly different between maize and pea starches (36.5 and 67.2 mmol/12 h respectively;sed24.1;P= 0.27) and net portal VFA flux was lower for maize starch than for pea starch (169 and 218 mmol/12 h respectively; SED 18;P= 0.054). Net portal fluxes of valine, isoleucine, phenylalanine, tryptophan, arginine, serine, cystine, tyrosine, lysine, histidine and the sum of essential amino acids tended to be or were higher (P< 0.1 orP<0.05) and net portal flux of aspartic acid tended to be lower for pea starch (P<0.1). It can be concluded that, although ileal digestibility of both starches is equal, the rate of appearance of glucose in the portal vein was higher for maize starch, influencing the net portal flux of amino acids.
Preference for flavoured foods by lambs conditioned with intraruminal administration of nitrogen
Authors: Villalba Juan J. , Provenza Frederick D.
Published: June 2005

We suggested that food preference depends on the interplay between flavour and post-ingestive effects, and we predicted that protein-restricted lambs would acquire preferences for foods paired with supplemental sources of N, including urea (Expts 1 and 2), casein (Expt 3), and gluten (Expt 4). In each experiment, twenty lambs, in two groups of ten, were conditioned as follows: on odd-numbered days, lambs in group 1 received wheat straw (Expts 1, 3, and 4) or ground barley (Expt 2) flavoured with a distinctive flavour, and lambs in group 2 received the same food but with a different flavour. On even-numbered days, flavours were switched and lambs received capsules containing different amounts of urea (ranging from 0.12 to 0.92 g N/d), casein (ranging from 0.23 to 0.69 g N/d), or gluten (ranging from 0.23 to 0.69 g N/d). After conditioning periods of 8 d, lambs were given a two-choice test to determine preference for flavours paired with N. In Expts 1 and 2, lambs preferred the flavours conditioned with urea at lower doses (0.12 g N/d in Expt 1. 0.23 and 0.46 g N/d in Expt 2), but they avoided the flavour associated with urea at the highest dose (0.23 g N/d in Expt 1 and 0.92 g N/d in Expt 2). In Expts 3 and 4, lambs avoided the flavours associated with the lowest doses of casein or gluten (0.23 g N/d), but they preferred the flavours paired with casein or gluten at higher doses (0.46 and 0.69 g N/d). After conditioning, N administrations were suspended and lambs in Expts 3 and 4 were offered a choice of the two flavours at weekly intervals for 2 weeks (extinction); preferences persisted during extinction. Collectively, these results suggest that the post-ingestive effects of N in different forms and concentrations influenced the development of food preferences by lambs.
Comparison and evaluation of mechanistic rumen models
Authors: Bannink A. , De Visser H. , Van Vuuren A. M.
Published: June 2005

Mechanistic rumen models of Baldwin (1995), Danfæer (1990) and Dijkstra et al. (1992) were compared on identical inputs that were derived from trials with lactating dairy cows fed on grass herbage. Consistent differences were detected between models and between predicted and observed outputs. None of the models seemed to predict all nutrient flows best. The models particularly differed in the representation of microbial metabolism: degradation of insoluble substrate, fermentation of substrate into volatile fatty acids, and incorporation of substrate into microbial matter. Differences amongst models in the prediction of these processes compensated for each other and consequently all models predicted the duodenal flow of non-NH3 N, microbial N and organic matter reasonably well. Large differences remained in the prediction of individual nutrient flows, however, and it was stressed that in order to enhance prediction of the profile of nutrient flows, the mechanisms of microbial metabolism need to be tested on their ability to describe the intraruminal transactions. However, this requires more-detailed information on individual nutrient flows and on the microbial or non-microbial origin of duodenal contents. Parameter inputs for physical and chemical feed properties were identified that are improperly defined in extant models or susceptible to error. The description of these feed characteristics needs to be developed further and become identifiable for a wide range of dietary conditions.
Ruminal and total plant cell-wall digestibility estimated by a combinedin situmethod utilizing mathematical models
Authors: Huhtanen Pekka , Vanhatalo Aila
Published: June 2005

Three ruminally and duodenally cannulated non-lactating Finnish Ayrshire cows were used to investigate ruminal and intestinal digestion of cell-wall carbohydrates by a combinedin situmethod. Five grasses cut at 10 d intervals were incubated in the rumen for 0, 6, 12, 24, 48, 72 and 96 h, and the undegraded residues were exposed to intestinal digestion. With advancing maturity of grass both the rate and extent of cell-wall digestion decreased. At early stages of growth the decreases were faster for the rate of digestion and at late stages of growth for the extent of digestion. Applying a passage rate of 0.02/h in one compartmental rumen model resulted in digestibility values markedly lower than typically observedin vivo.However, applying a rumen model incorporating a selective retention of particles and time-dependent release of particles from the non-escapable pool resulted in much higher digestibility values. Recovery of lignin after 96 h ruminal incubation with a subsequent mobile-bag incubation was very low (from 244 to 460 mg/g). Intestinal disappearance of neutral-detergent fibre (NDF) and hemicellulose decreased with advancing maturity of grass and with increasing length of preceding ruminal incubation period, i.e. with decreasing potential digestibility of the material. Disappearance of hemicellulose was much greater than that of cellulose for intact grasses but the difference diminished with increasing length of preceding rumen incubation period. On average, 195 mg/g of potentially digestible NDF disappeared from the mobile bags in the intestines. The post-ruminal digestion as a proportion of the total NDF digestibility varied between 0.034 and 0.058. Despite methodological problems both in ruminalin situand intestinal mobile bag techniques, these methods can be used to investigate ruminal and intestinal cell-wall digestion and to partition cell-wall digestibility between ruminal and post-ruminal digestion providing that appropriate rumen models are used.