The gastrointestinal (GI) effects of three different dietary fibre (DF) sources: wheat bran (WB), oat bran (OB) and pea fibre (PF), were compared with a low-fibre diet in a 4-week trial with rats (initial body-weight 210 g). The DF sources varied widely in chemical composition, solubility and water-holding properties, and particle size. The DF sources were mixed into diets to comprise the same amount of non-starch polysaccharides (NSP; 135 g/kg dry matter (DM)). Compared with the control diet, all fibre-containing diets reduced apparent digestibility of DM, energy, and protein significantly but to different extents. The ranking order of faecal DM bulking followed that of NSP recovery in the faeces: WB > OB > PF > control. The elongating effect of the diets on the GI tract was most pronounced in the rats fed on the OB diet. The mean transit time (MTT) of the OB diet was similar to that of the control diet (approximately 37 h), which was significantly slower than the MTT of the WB and PF diets (approximately 23 h). The study confirms that no simple cause and effect relationship exists between chemical composition, physical properties, and physiological effects of dietary fibre and their effects along the GI tract

The suitability of l-[3-3H]valine for measuring valine oxidation was studied by comparing its oxidation rate with that of l-[1-14C]valine in rats and pigs. l-[3-3H]valine was synthesized by removal of the tritium on carbon-2 of l-[2,3-3H]valine by acetylation. The acetyl group was removed enzymatically using pig renal acylase 1 (EC 3.5.1.14) and the product was purified by ion-exchange and paper chromatography. For the first rat experiment l-[3-3H]valine was synthesized in our laboratory; for the subsequent experiments it was produced by Amersham International plc. In the first experiment in rats the two tracers were given by injection and 14CO2 was collected for 2 h. The oxidation of tritiated valine was significantly higher than that of l-[1-14C]valine. In a second experiment there was no difference. This was probably due to the higher purity of the labelled valine which, for the second experiment, was shown by nuclear magnetic resonance to contain only one tritium atom. In a study with pigs in which the two tracers were given by continuous infusion there was no significant difference between them in flux or oxidation. The results of this experiment were used to evaluate a model to estimate amino acid requirements. With pigs given a methionine-limiting diet a reduction in methionine intake, by reducing protein accretion, increased valine oxidation by the same proportion.

Six Large White pigs (mean body-weight 59 (se 1.7) kg) were surgically fitted with permanent catheters in the portal vein, the brachiocephalic artery and the right hepatic vein, as well as with electromagnetic flow probes around the portal vein and the hepatic artery, and allowed to recover. The non-anaesthetized animals were given a basal non-fibre diet (diet A) alone or together with 60 g guar gum/kg (diet B) or 150 g purified cellulose/kg (diet C) by substitution for mica. The diets were given for weekly periods and according to a replicated 3x3 Latin square design. On the last day of each such adaptation period, test meals of 800 g were given before blood sampling. Sampling was continued for 8 h. Guar gum strongly reduced glucose apparent absorption without changing the absorption and the hepatic uptake profiles. Production rates of insulin, gastric inhibitory polypeptide and insulin-like growth factor-1 (IGF-1) were lowest after guar gum ingestion. However, the reductions in peripheral blood insulin levels caused by guar gum were not associated with a change in hepatic insulin extraction. IGF-1 appeared to be strongly secreted by the gut, whereas the liver had a net uptake of the peptide. Ingestion of guar gum increased the hepatic extraction coefficient of gut-produced IGF-1. Guar gum ingestion appeared also to decrease glucagon secretion.

Cellulose at the level consumed had very few effects on the variables considered.

It is suggested that the modulation of intestinal mechanisms by guar gum was sufficient to mediate the metabolic effects described

The effects of level of feed intake (0.8, 1.2 and 1.6 kg/d) and body-weight of the pig (49 and 92 kg) in Expt 1, and dietary neutral-detergent fibre (NDF; 30, 60, 90, 120 and 150 g/kg) in Expt 2 on the endogenous ileal flow of amino acids (AA) and nitrogen were studied with protein-free diets into which purified wood cellulose was incorporated at the expense of maize starch. In Expt 1, one of the protein-free diets containing 90 g NDF/kg was used. Female pigs were fitted with a simple ‘T’ cannula at the terminal ileum. In Expt 1, the endogenous ileal AA and N flow, expressed as g/kg dry matter (DM) intake, decreased significantly (P < 0.05) with increasing DM intake, except for proline. By contrast, the values expressed as g/d remained constant. There was no significant difference in endogenous ileal flow (P > 0.05) between initial body-weights of 45 and 90 kg except for histidide, isoleucine, phenylalanine, threonine, valine and serine, in which the ileal flow determined at the higher body-weight was significantly higher (P < 0.05). In Expt 2, the effects of dietary cellulose levels on the endogenous ileal flow of AA and N were not significant (P > 0.05), although the values tended to increase as dietary cellulose levels increased for most AA and for N. It is concluded that the daily endogenous ileal flow of AA and N remains relatively similar at different DM intake and cellulose levels. Therefore, correction of apparent ileal digestibility of AA and N to the true ileal digestibility should be made with the endogenous ileal flow values expressed on a daily amount basis, not the values expressed on a DM intake basis

The efficiency of clearance of plasma triacylglycerols (TAG) after fatty meals in non-diabetic Caucasian subjects is believed to determine the plasma level of high-density-lipoproteins-cholesterol (HDL-C). It is unknown if this observation holds in diabetic subjects and in other racial groups. In assessing the factors that determine TAG responses to acute fat loading in a tropical African population with a low prevalence of atherosclerotic disease, twenty (nine obese) non-insulin-dependent diabetic (NIDDM) patients with optimal glycaemic control and twelve (six obese) age-matched non-diabetic subjects were given meals containing 50 g fat (in butter) and 75 g carbohydrate (in white bread) over 15 min in the morning after a 12 h overnight fast. The fasting plasma levels of glucose, TAG, total cholesterol (total-C), HDL-C, low-density-lipoprotein-cholesterol, insulin and glycosylated haemoglobin (HBAlc) were estimated; glucose and TAG levels were also measured postprandially for 8 h at 2 h intervals. Postprandial lipaemia was consistently higher in the diabetic patients (about 50–100% more than values obtained in the non-diabetic subjects, even when corrected for differences in body mass) and correlated positively with age and postprandial glycaemia. This defect in TAG clearance was even worse (by about 50%) when glucose tolerance became further impaired after ten of the diabetic patients stopped oral hypoglycaemic treatment for 1 week and the fat-tolerance test was repeated. In the obese non-diabetic subjects, but not those of normal weight, there were significant negative relationships between the postprandial lipaemia and fasting plasma levels of HDL-C and the HDL-C: total-C ratio, as reported in Caucasians. It is concluded that age and the ambient glucose concentration appear to be the important determinants of the efficiency of TAG clearance in diabetic subjects. This accords with clinical observations of increased atherogenic liability with increasing age and poorer glycaemic control. The determinants in non-diabetic subjects were less defined, indicating that postprandial lipaemia might be influenced by various factors (obesity as shown here) in different subsets of individuals.

The colonic fermentation of ispaghula, a mucilage from Plantago ovata composed mainly of arabinoxylans, and its effects on stool output and caecal metabolism were investigated. Four groups of eight rats were fed on a basal diet (45 g non-starch polysaccharides/kg) for 28 d. The diet was then supplemented with ispaghula (g/kg; 0, 5, 15 or 50) for 28 d. Ispaghula increased stool dry weight and apparent wet weight but faecal water-holding capacity (amount of water held per g dry faecal material at 0.2 mPa) was unchanged. The extent of faecal drying in the metabolism cages was measured for rats fed on the basal diet and 50 g ispaghula/kg diet. At the faecal output levels encountered, only an 8% loss of wet weight would be predicted over 24 h and this was independent of diet. Faecal short-chain fatty acid (SCFA) concentration did not change but SCFA output increased. The molar proportion of SCFA as propionic acid increased and faecal pH was reduced. Values from pooled faecal samples suggested that approximately 50% of the ingested ispaghula was excreted by the 50 g ispaghula/kg diet group. Diaminopimelic acid (a constituent of bacterial cells) concentrations fell but output was unchanged indicating no change in bacterial mass. Similar changes were seen in the caecal contents but caecal pH and SCFA were unaffected. Ispaghula increased both caecal and colonic tissue wet weight and colonic length. Our results suggest that ispaghula is partly fermented in the rat caecum and colon, and loses its water-holding capacity. However, it is still an effective stool bulker and acts mainly by increasing faecal water by some unknown mechanism

Nine healthy male subjects consumed a daily fish oil supplement providing 2.1 g docosahexaenoic acid (22:6 n-3; DHA) and 0.8 g eicosapentaenoic acid (20:5 n-3; EPA) for 6 weeks. The proportion of EPA and DHA in plasma, erythrocytes, leucocytes and platelet phospholipids was increased by the supplement. Plasma concentration of triacylglycerol and very-low-density-lipoprotein-cholesterol were lowered and those of high-density-lipotrotein (HDL)- and HDL2-cholesterol and apoprotein B were increased. Platelet aggregation and thromboxane B2 production induced by collagen were partially inhibited. Both systolic and diastolic blood pressure fell during treatment and rose following withdrawal of the supplement. Statistically significant reductions in erythrocyte counts, packed cell volume and haemoglobin and increases in total leucocyte and monocyte counts occurred with the supplement. Plasma α-tocopherol concentrations fell below the normal range during the period of supplementation. It is suggested that future studies consider components other than EPA in fish oil. Further studies are needed to investigate the extent to which fish oil increases the requirement for antioxidant nutrients.

An attempt was made to unravel further the mechanism by which high dietary concentrations of ascorbic acid influence copper metabolism. The addition of ascorbic acid to the diet of rats caused about a twofold increase in plasma ascorbate concentrations and reduced group mean plasma and tissue concentrations of Cu. The effect of 10 g ascorbic acid/kg diet was greater than that of 1 g/kg. Ascorbic acid feeding reduced blood haemoglobin concentrations and packed cell volume values. Dietary ascorbic acid caused a significant decrease in apparent Cu absorption from the intestine. Ascorbate, intravenously administered together with 64Cu, caused an increase in 64Cu in the liver. Ascorbate, at concentrations occurring in plasma after ascorbic acid feeding, promoted the uptake of 64Cu by isolated hepatocytes. Thus, ascorbate stimulated the efficiency of hepatic uptake of Cu. Ascorbate, intravenously administered together with 64Cu, stimulated accumulation of 64Cu in bile of rats with a bile duct cannula. In rats fed on ascorbic acid, intravenously administered 64Cu was recovered in bile at increased rates. Dietary ascorbic acid enhanced the recovery of intraperitoneally administered 64Cu in faeces. The ascorbate-induced stimulation of biliary 64Cu excretion may reflect an increased hepatic uptake of 64Cu and be caused by an increased specific activity of Cu in liver pools. It is suggested that dietary ascorbic acid reduces tissue Cu concentrations primarily by interfering with intestinal Cu absorption. Ascorbate increases the efficiency of hepatic uptake of Cu, but this effect may not be causatively related with the reduced tissue Cu concentrations after ascorbic acid feeding

The purpose of the present study was first to assess the extent to which unlabelled ascorbate in the diet of guinea-pigs can exchange with labelled ascorbate within their organs when the dietary intake is varied over a wide range, and second to determine whether the retention of label might be used to assess either the amount of ascorbate intake or its biological availability where these are not known. The retention of [14C]ascorbate in the body and in various organs of guinea-pigs were, therefore, measured following a 13 d period of graded dietary intakes of ascorbate. It was found first, that the amount of label retained in each of the organs, 13 d after the initial dose of labelled ascorbate, was much more closely related to the amount of ascorbate intake after labelling than to the intake (and tissue ascorbate levels) before and at the time of labelling. Second, most of the individual internal organs exhibited a constant relationship between the specific activity at 13 d and the dietary intake, except for brain which was flushed to a smaller extent. Third, in agreement with several previous studies a high proportion of the radioactive label in the tissues was found to be still present in ascorbate. The specific activity of column-purified ascorbate was very similar to the estimated specific activity in the crude extract, which implies that it may be possible to estimate specific activities (or stable isotope enrichments) at certain sites without rigorous isolation procedures. Fourth, the amount of radioactivity appearing in the urine 2 d before killing the animals was correlated with the amount of ascorbate intake and with tissue specific activities, suggesting that intakes (or bioavailability) might be predicted from the patterns of label-appearance in the urine

The effects of adaptation to dietary fat of different degrees of unsaturation (olive oil and sunflower oil) on bile secretion were studied in dogs at rest and after food intake. The animals were prepared with a bidirectional biliary cannula and a duodenal cannula to provide bile return. The two experimental groups were fed on diets containing 150 g fat/kg in the form of either olive oil (O) or sunflower-seed oil (S). The flow-rate under resting conditions and the patterns of response to food were similar in both experimental groups, although postprandial hypersection were significantly greater in volume and more prolonged in group O. No appreciable differences in concentration and output of biliary cholesterol or phospholipids were noted between the two groups. In contrast, the concentration and output of bile acids differed significantly both at rest and after food: concentration and output of bile acids were greater at rest in group S. However, after food intake, these responses were increased only in group O. The results suggest that the type of dietary fat affects biliary response to food, probably through differences in the contribution of the gall bladder in the two experimental groups.

Effects of cassava (Manihot esculenta Crantz)-borne organic cyanide and inorganic cyanide in the form of sodium cyanide on bone and muscle development were investigated in eighteen dogs of Nigerian breed. After 16 weeks of stabilization in the laboratory from the time of purchase when the dogs were fed on the same diet, they were randomly assigned to three experimental groups of six dogs each. The control group was fed on rice while the other two groups were fed on either cassava (gari) or rice plus cyanide. The three diets were made isoenergetic and isonitrogenous by varying the quantity of meat incorporated into them. The results obtained after 14 weeks of feeding the respective diets indicated that there was retardation of muscle development in the gari-fed dogs. This may have resulted from gluconeogenesis from muscle protein associated with suppression of production of insulin by the pancreas in this group. The results indicated also that the effects of inorganic dietary cyanides on muscle development were different. Both forms of dietary cyanides, however, had no adverse effect on bone development

The present study investigated the effect of feeding maize-oil, olive-oil and fish-oil diets, from weaning to adulthood, on rat mammary tissue and erythrocyte phospholipid fatty acid compositions. Effects of diet on the relative proportions of membrane phospholipids in the two tissues were also investigated. Mammary tissue phosphatidylinositol (PI) fatty acids were unaltered by diet, but differences in phosphatidylethanolamine (PE) and, to a lesser extent, phosphatidylcholine (PC) fractions were found between animals fed on different diets from weaning. Differences observed were those expected from the dietary fatty acids fed; n-6 fatty acids were found in greatest amounts in maize-oil-fed rats, n-9 in olive-oil-fed rats, and n-3 in fish-oil-fed rats. In erythrocytes the relative susceptibilities of the individual phospholipids to dietary modification were: PE > PC > PI, but enrichment with n-9 and n-3 fatty acids was not observed in olive-oil- and fish-oil-fed animals and in PC and PE significantly greater amounts of saturated fatty acids were found when animals fed on olive oil or fish oil were compared with maize-oil-fed animals. The polyunsaturated: saturated fatty acid ratios of PE and PC fractions were significantly lower in olive-oil- and fish-oil-fed animals. No differences in the relative proportions of phospholipid classes were found between the three dietary groups. It is suggested that differences in erythrocyte fatty acid composition may reflect dietary-induced changes in membrane cholesterol content and may form part of a homoeostatic response the aim of which is to maintain normal erythrocyte membrane fluidity. The resistance of mammary tissue PI fatty acids to dietary modification suggests that alteration of PI fatty acids is unlikely to underlie effects of dietary fat on mammary tumour incidence rates.

A series of experiments was designed to evaluate inert markers employed in studies of ileal and faecal apparent digestibilities of nitrogen and amino acids in pigs fitted with simple ‘T’ piece cannulas. Trial 1 assessed the palatability of diets containing (a) 5 g chromic oxide/kg, (b) 1 and (c) 5 g titanium dioxide/kg at two levels of feeding. The results indicated that there were slight problems in terms of period of feed consumption associated with diets (a) and (c), but that these effects were transitory and disappeared following acclimatization, although higher levels of feeding may compound the problem. Trial 2 estimated N balance, faecal apparent digestibility of amino acids as determined by both total collection and ratio of markers, ileal apparent digestibility of amino acids and recovery of markers using diets containing (a) 1 and (b) 5 g Cr2O3/kg, (c) 1 and (d) 5 g TiO2/kg. An additional assessment of acid-insoluble lignin present within the diet was also undertaken. Cr2O3 was associated with the lowest recovery, whilst calculations based on TiO2 gave lower standard errors. Trial 3 examined diurnal variation in digesta sampling and its effect on faecal apparent digestibility of N and amino acids. There were no evident effects. In general, it was concluded that the most appropriate marker to use in studies of this nature was TiO2 at a rate of 1 g/kg.

Feeding growing mice on diets containing raw field beans (Vicia faba var. minor) as the only source of protein brought about an impairment in growth, muscle mass and liver weight. No changes in food consumption were observed, but the food intake:weight gain ratio was increased in those animals. Plasma protein, triacylglycerols and cholesterol values were not affected by the dietary treatment although serum glucose and zinc levels fell after legume intake as well as the number of circulating erythrocytes. The relative enlargement of thymus and spleen in the legume-fed mice was apparently accompanied by a reduction in the cell number and an increase in cell size, while the protein synthesis capacity followed differentiated patterns in both tissues when assessed through protein, DNA and RNA determinations. The haemagglutination titres and the number of rosette-forming cells were lower in those animals fed on the field bean diet as well as the splenic lymphocyte responses to phytohaemagglutinin, Concanavalin A or lipopolysaccharide mitogens used to evaluate the functional status of T and B lymphocytes. The present study describes, apparently for the first time in mice, the involvement of field bean intake in some immunological disturbances affecting both humoral- and cell-mediated aspects of the immune response

Zinc deficiency was induced in adult male mice by feeding them for 8 weeks on a purified semi-synthetic Zn-deficient diet (ZD) containing 90 g lipid/kg (60 g maize oil plus 30 g cod-liver oil). One group was then fed on a low-lipid Zn-deficient diet (ZDLR) containing 30 g cod-liver oil/kg as the sole lipid source for a further 8 weeks. At the end of the experiment the stomach clearance rate, daily food intake, body-weight gain and [14C]glucose uptake in the intestine were significantly higher in group ZDLR than in mice that continued eating the Zn-deficient lipid-adequate diet ZD, and were comparable to results for a group given a Zn-supplemented diet. These results suggest that the pathogenesis of anorexia, nutrient malabsorption and growth retardation are secondary to lipid malabsorption resulting from Zn deficiency

The effect of the weaning diet on the subsequent colonic metabolism of bran and pectin in the adult rat has been investigated. Feeding a fibre-reduced diet on its own or supplemented with bran (WB) and pectin (P) from weaning (fibre-reduced (weaning)) was compared with introducing the same diet to age-matched rats reared on a standard laboratory diet from weaning (fibre-reduced (6 weeks)). The effects of the diets on colonic metabolism were measured by wet and dry caecal contents and stool weights, caecal sac weight, and caecal and faecal short-chain fatty acids (SCFA). Final body-weights were greater for fibre-reduced (6 weeks) and fibre-reduced (6 weeks)+P groups, but not fibre-reduced (6 weeks)+WB, than those of the fibre-reduced (weaning) rats. Rats fed on fibre-reduced (6 weeks) diet had a higher total caecal SCFA content than fibre-reduced (weaning) control rats. Fibre-reduced (weaning)+P-fed rats had a threefold higher caecal concentration of both propionate and butyrate than the matched fibre-reduced (6 weeks)+P group. Fibre-reduced (weaning)+WB animals had a significantly higher butyrate caecal concentration compared with their matched fibre-reduced (6 weeks)+WB group. Fibre-reduced (weaning)+P-fed rats had a lower faecal output than the fibre-reduced (6 weeks)+P rats. There was no difference in faecal output in rats fed on either fibre-reduced (6 weeks)+ WB or fibre-reduced (weaning)+WB. The faecal concentration of SCFA was in general higher in the rats fed on fibre-reduced (weaning) alone, +P, or +WB than in those fed on fibre-reduced (6 weeks) alone, +P or +WB. Faecal output of total and individual SCFA was increased on the fibre-reduced (weaned)+WB diet compared with fibre-reduced (6 weeks)+WB-fed animals. The diet at weaning may be important in determining the pathways of caecal bacterial metabolism in the adult rat. In studying the effect of a dietary fibre on caecal metabolism and faecal output, when the diet is changed appears to be important

The pentose sugar l-arabinose is one of the most abundant components released by complete hydrolysis of non-starch polysaccharides of feed ingredients of vegetable origin. Two studies were conducted to investigate the apparent ileal digestibility and urinary excretion of l-arabinose at dietary inclusion levels of 50 and 100 g/kg, and 25, 50, 75 and 100 g/kg respectively, in pigs. As a reference, d-glucose was included in the studies. Water intake, ileal flow of volatile fatty acids and ileal and faecal digestibilities of dietary nutrients in pigs fed on the different diets were also examined. Castrated pigs were prepared with a post-valvular T-caecum cannula to measure ileal digestibility. Faecal digestibility was measured in non-cannulated pigs. Apparent ileal digestibility of l-arabinose was found to be approximately 70%. The presence of l-arabinose in the diet increased ileal flow of volatile fatty acids and lactic acid, suggesting the occurrence of microbial degradation of l-arabinose in the pig small intestine. l-arabinose was partly excreted in the urine. The extent of this urinary excretion as a percentage of intake increased linearly (P < 0.01) as the dietary level increased. In pigs fed on the 25 g l-arabinose/kg diet, 10.9% of the l-arabinose consumed appeared in the urine. This level was increased to 14.7% when pigs were fed on a diet containing 100 g l-arabinose/kg diet. Faecal digestibility and retention of nitrogen decreased significantly in pigs fed on the l-arabinose diets.

Altogether twenty-six elderly subjects (aged 65–74 years) with persistent impaired glucose tolerance (World Health Organization (1985) criteria) identified in a population-based study, were randomly treated either with chromium-rich yeast (160 μg Cr/d) or with placebo for 6 months. The 24 h urinary Cr increased from 0.13 (se 0.03) to 0.40 (se 0.06) μg/d in the Cr group (n 13) but no change was found in the placebo group (n 11) (0.13 (se 0.02) v. 0.11 (se 0.02) μg/d). No significant change was observed in the oral glucose tolerance test (glucose dose 75 g; 0, 1 and 2 h blood glucose respectively): 5.3 (se 0.1), 9.3 (se 0.3), 8.2 (se 0.3) mmol/l v. 5.0 (se 0.1), 8.5 (se 0.4), 7.3 (se 0.5) mmol/l in the Cr group; 4.9 (se 0.2), 9.2 (se 0.6), 8.1 (se 0.3) mmol/l v. 4.8 (se 0.2), 8.5 (se 0.5), 7.0 (se 0.6) mmol/l in the placebo group (baseline v. 6 months). Glycosylated haemoglobin, plasma insulin, C-peptide and apolipoprotein Al and B levels remained unchanged, and no improvement was seen in serum total cholesterol (6.2 (se 0.3) v. 6.4 (se 0.3) mmol/l for the Cr group, 6.2 (se 0.4) v. 6.5 (se 0.3) mmol/l for the placebo group), high-density-lipoprotein-cholesterol (1.1 (se 0.1) v. 1.2 (se 0.1) mmol/l for the Cr group, 1.0 (se 0.1) v. 1.1 (se 0.1) mmol/l for the placebo group) or triacylglycerols (2.5 (se 0.4) v. 2.0 (se 0.4) mmol/l for the Cr group, 2.4 (se 0.2) v. 2.5 (se 0.2) mmol/l for the placebo group). The present results indicate that Cr supplementation does not improve glucose tolerance or serum lipid levels in elderly subjects with stable impaired glucose tolerance.

During a controlled zinc depletion-repletion study, fifteen men aged 25.3 (sd 3.3) years were fed on a low-Zn diet with high phytate:Zn and phytate × calcium: Zn molar ratios for 7 weeks, followed by a 2 week repletion period when 30 mg supplemental Zn/d was given. Changes in plasma, urine, and hair Zn concentrations, taste acuity, and cellular immune response confirmed the development of mild Zn deficiency. Zn concentrations in neutrophils, platelets, erythrocytes and erythrocyte membranes, mean platelet volume, and activities of alkaline phosphatse (EC 3.1.3.1) and α-d-mannosidase (EC 3.2.1.24) in neutrophils did not respond to changes in Zn status. In contrast, alkaline phosphatase activity in erythrocyte membranes showed a significant decline which was consistent in all subjects (nmol product formed/min per mg protein; baseline v. 7-week Zn depletion, 0.656 (sd 0.279) v. 0.506 (sd 0.230), at 7 weeks; P < 0.05); neutral phosphatase activity remained unchanged. Alkaline phosphatase activity in erythrocyte membranes may be a potential index of Zn status in humans

The effect of vitamin A deficiency or the lentogenic La Sota strain of Newcastle disease virus (NDV) infection, or both, on immunoglobulin (IgA and IgM) levels in bile and plasma were investigated. In addition, tissue distribution of IgA-, IgG- and IgM-containing cells was studied to establish the source of these Ig. Chickens (1-d-old) with limited vitamin A reserves were fed ad lib. on diets containing either marginal or adequate levels of vitamin A. At 4 weeks of age, half the chickens in each group were infected with NDV. The number of IgA- and IgM-containing cells was not significantly affected by vitamin A deficiency, demonstrating that neither class-switching nor homing of Ig-containing cells is influenced by vitamin A deficiency. Although bile IgM levels were not significantly different in vitamin A-deficient chickens compared with normal chickens, IgA levels were significantly lower. This decrease was even more pronounced in deficient NDV-infected chickens, despite the higher number of IgA-containing cells found in these birds. These results, together with the slightly increased levels of IgA in plasma of vitamin A-deficient chickens, suggest that the hepatobiliary transport of IgA is impaired by vitamin A deficiency and possibly also by NDV infection, although disturbed secretion by IgA-containing cells cannot be excluded