bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro energy costs of NA+, K+ATPase activity and protein synthesis in muscle from calves differing in age and breed
Authors: Gregg V. A. , Milligan L. P.
Published: May 2005

1. An in vitro preparation was used to measure rates of oxygen consumption, Na+, K+-ATPase-dependent respiration, [14C]phenylalanine incorporation and tyrosine release of skeletal (stenomandibularis) muscle from 10-21 -d-old (three) and 7-month dairy (three) calves and control (CDM; four) and extreme double-muscled (EDM; two) calves.

2. Rate of oxygen consumption was greatest (P< 0.001) for muscle from 10.21-d-old dairy calves and lowest (P< 0.05) for CDM calves.

3. Ouabain (10−6M) caused a 40% inhibition of muscle respiration.

4. Na+, K+-ATPase-dependent respiration was similar for muscle from all calf groups except 10-21-d-old dairy calves which had a value 26% greater (P< 0.001) than that of older dairy calves.

5. Na+, K+-ATPase-independent respiration was 16% greater (P< 0.001) for muscle from 10.21-d-old than that of older dairy calves while muscle from EDM calves had a value 11 % greater than that of CDM caives.

6. The rate of [14C]phenylalanine incorporation was greater (P< 0.05) for muscle from 10-21-d-old dairy than from older dairy calves, similar between older dairy and CDM calves, and decreased (P< 0.05) for EDM calves.

7. Rate of tyrosine release was greatest (P< 0.05) for muscle from CDM and EDM calves: both dairy groups had similarly low rates of muscle tyrosine release.

8. The energy estimated to be required for peptide bond synthesis accounted for 2.0–3.3% of the O2consumption of the muscle preparations.
The influence of diet on the exocrine pancreatic secretion of growing pigs
Authors: Partridge I. G. , Low A. G. , Sambrook I. E. , Corring T.
Published: May 2005

1. Pancreatic juice was collected from six pigs of 48 kg initial weight fitted with a collection catheter in the pancreatic duct and a return catheter in the duodenum.

2. Measurements of flow and composition of the juice were made during 24 h periods after adaptation to isonitrogenous diets based on barley, wheatings and fish meal (diet BWF) or starch, sucrose, casein, maize oil and cellulose (diet SSC), given in a change-over design. Measurements were also made during the periods of adaptation to a change from one diet to the other.

3. Mean flow-rates for pigs adapted to diets showed a highly significant four-fold difference between diets; values were 4962 ml/d for diet BWF and 1273 ml/d for diet SSC. The hourly volumes of juice were very variable and showed no clear response to feeding and no consistent diurnal pattern for either diet.

4. There were no significant differences between diets in the specific activities of the proteases. Average values were (units/nig protein) trypsin. (EC3.4.21.4) 29·6, chymotrypsin (EC3.4.21.1) 7·7, carboxypeptidase A (EC3.4.17.1) 0·65, carboxypeptidase B (EC3.4.17.2) 1.6. The total output of each tended to be higher with diet BWF than with diet SSC. The specific activities and tolal outputs of α-amylase (EC3.2.1.1) and lipase (EC3.1.1.3) were significantly higher for diet BWF than for diet SSC; specific activities for the two diets respectively were: (units/mg protein) α-amylase 95·6 and 42·3, lipase 59·0 and 14·5.

5. The higher daily volume of juice with diet BWF was associated with significantly (but only slightly) higher levels of both sodium and potassium, compared with diet SSC.

6. The results are discussed in relation to previous studies on digestion at this Institute, in which pigs with intestinal cannulas were given the same diets.
Interrelationships between biotin, choline and other B-vitamins and the occurrence of fatty liver and kidney syndrome and sudden death syndrome in broiler chickens
Authors: Whitehead C. C. , Randall C. J.
Published: May 2005

1. Addition of supplemental choline to a biotin-deficient diet decreased the biotin status of chicks and increased mortality from fatty liver and kidney syndrome (FLKS).

2. Mortality was also increased by dietary supplementation with a mixture of other B-vitamins, excluding biotin, and was highest when the choline and B-vitamin supplements were combined.

3. The occurrence of sudden death syndrome (SDS) was unaffected by dietary biotin concentration.

4. A previously unreported condition was observed in which birds died showing post-mortem signs characteristic of both FLKS and SDS and whose occurrence was related to the biotin status of the chicks.
The metabolism of maltitol in the rat
Authors: Lian-Loh Rebecca , Birch Gordon G. , Coates Marie E.
Published: May 2005

1. Conventional (CV) rats were given a single oral dose of 1 or 2 g maltitol. Urine and faeces were collected during the following 24 h and their contents of maltitol and sorbitol were measured.

2. Very little of either substance appeared in the faeces but appreciable amounts of sorbitol found in the urine indicated that the maltitol had been hydrolysed.

3. Excretion of maltitol and sorbitol was compared in germ-free and CV rats given an oral dose of 2 g maltitol. Significantly less of both substances was recovered in the faeces of CV rats, but urinary excretion was similar in both environments.

4. Maltitol injected intravenously gave rise to only traces of sorbitol in the excreta. A dose of 250 mg was cleared almost completely from the circulation within 1 h.

5. It is concluded that maltitol is hydrolysed by animal tissues, either in the gut lumen before absorption or in the gut wall during absorption. Maltitol and sorbitol are also degraded by gut bacteria, mostly in sites distal to the main absorptive area. The contribution to the host's nutrition would depend on the extent to which the end-products of fermentation are absorbed from the colon.
The origin of urinary aromatic compounds excreted by ruminants
Authors: Martin A. K.
Published: May 2005

1. Dietary phenolic cinnamic acids are hydrogenated in the side-chain, demethylated and dehydroxylated in the rumen and are responsible for the large urinary output of benzoic acid by ruminants.

2. Decarboxylation of phenolic acids to simple phenols is another reaction of the intestinal microflora and experiments were made to determine the extent of this reaction in the rumen of sheep.

3. In five experiments phenolic compounds, quinic acid or casein were infused into therumen or abomasum of sheep and increments in urinary outputs of phenolic acids and phenols determined by thin-layer and gas-liquid chromatography.

4. Production of phenols was almost exclusively confined to reactions in the rumen.

5. Rumen administration of phenolic benzoic or phenylacetic acids which contained a 4-hydroxy substituent yielded large increments in urinary phenol outputs. Other phenolic benzoic and phenylacetic acids were not decarboxytated. Rumen decarboxylation of 4-hydroxy-3-phenylpropionic acid did not occur and decarboxylation of 4-hydroxycinnamic acids was slight.

6. Nearly half the tyrosine content of rumen-administered casein was excreted asp-cresol, a decarboxylation product of 4-hydroxyphenylaceticacid,p-Cresol was the principal phenol found in sheepurine.

7. Catechol and phenol were consistently found in sheep urine samples andp-ethylphenol, resorcinol, quinol, 4-methylcatechol, orcinoland pyrogallol were also found when suitable precursors were infused to the rumen.

8. It is concluded thatp-cresol is a rumen metabolite of tyrosine. The other phenols found are microbial metabolites of phenolic precursorswhich are either widely distributed in plants such as 4-hydroxybenzoic, protocatechuic andvanillic acids or of more limited distribution such as the orcinol glycosides of some Ericaceous plants.
Effect of diet and infusion of volatile fatty acids into the rumen on the concentration of plasma free amino acids in sheep
Authors: Mercer J. R. , Miller E. L.
Published: May 2005

1. The effect of supplementing barley diets with urea (U), extracted decorticated groundnut meal (GNM) or Peruvian fish meal (PFM) on plasma free amino acid concentrations in sheep have been examined and the first limiting amino acid has been indicated by measuring the changes in the concentration of the plasma essential amino acids (PEAA) during a rumen infusion of a volatile fatty acid (VFA) mixture.

2. Three wethers fitted with rumen and re-entrant duodenal cannulas were given isonitrogenous, isoenergetic diets containing (g/kg dry matter (DM)) U 20, GNM 106 or PFM 78, the crude protein (nitrogen × 6.25) contents being 139, 145 and 148 respectively. The sheep were fed hourly, the mean daily dm intake being 0.634 kg.

3. Plasma concentrations of valine, threonine, lysine, isoleucine and leucine were linearly related to their concentrations in duodenal digesta.

4. A VFA mixture was infused into the rumen for 6 h to supply (mmol/min) acetate 1.47, propionate 0.22 andn-butyrate 0.27. Blood samples were taken 6 h before, during and 12 h after the end of the infusion.

5. The concentration of all PEAA decreased relative to the pre-infusion and post-infusion controls but there were no significant differences between diets.

6. The mean decreases in concentration averaged over all three diets showed that the decrease in concentration of methionine (41.5%) was far greater than for any other essential amino acid suggesting that under these conditions methionine was the first limiting amino acid.
The effect of protein- and non-protein-nitrogen supplements to maize silage on total amino acid supply in young cattle
Authors: Cottrill B. R. , Beever D. E. , Austin A. R. , Osbourn D. F.
Published: May 2005

1. A total of six diets based on maize silage were formulated to examine the effect of protein- and non-protein-nitrogen, and energy supplementation on the flow of amino acids to the small intestine and the synthesis of microbial amino acids in the rumen of growing cattle. All diets contained 24 g totai nitrogen (N)/kg dry matter (DM), of which 550 g N/kg total N was supplied by either urea or fish meal. Four diets contained low levels of barley (estimated total dietary metabolizable energy content of 10·4 M J/kgDM) and urea-N and fish meal-N were supplied in the ratios 3:1, 1·4:1, 0·6:1 and 0·3:1. The other two diets contained between 300 and 400 g barley/kg total diet (11·3 MJ metabolizable energy/kg DM) and the urea-N to fish meal-N ratios were 3:1 and 0·3:1.

2. On the four low-energy diets, fish meal inclusion tended to reduce the extent of organic matter (OM) digestion in the rumen but significantly increased duodenal amino acid supply (P< 0·05) in a quadratic manner. Microbial-N synthesis was increased by the two intermediate levels of fish meal supplementation but declined at the highest level of inclusion. With increasing levels of fish meal inclusion, a greater proportion of the dietary protein was found to escape rumen degradation and the apparent degradabilities of fish meal and maize-silage protein of all four diets were estimated to be 0·22 and 0·73 respectively.

3. The substitution of barley for part of the maize silage enhanced duodenal supply of amino acids, irrespective of the form of the N supplement, and stimulated microbial amino acid synthesis. For all diets efficiency of microbial-N synthesis was found to vary between 22·5 and 46 g N/kg rumen-digested OM. Contrary to what was found for low-energy diets, the inclusion of fish meal tended to reduce the flow of dietary protein to the small intestine, but these differences were not statistically significant.

4. The results appertaining to microbial synthesis, dietary protein degradabilities and duodenal amino acid flow for all diets are discussed in relation to the Agricultural Research Council (1980) proposals for the protein requirements of ruminants, and the production responses observed when similar diets were fed to growing cattle.
Formaldehyde-treated proteins for dairy cows – effects on blood hormone concentrations
Authors: Oldham J. D. , Hart I. C. , Bines J. A.
Published: May 2005

1. Seven Friesian heifers in mid-lactation were used in an experiment to measure the effects of including casein, formaldehyde-treated casein or formaldehyde-treated soya-bean meal in the diet on performance and on the concentrations of certain metabolites and hormones in the blood.

2. Milk yield and the concentration of fat, protein and lactose in milk were not affected by the treatments.

3. The concentration of growth hormone (GH) in jugular venous blood was higher with both formaldehyde-treated proteins than it was with untreated casein (P< 0·05). Diet had no effect on insulin, prolactin or thyroxine concentrations in blood.

4. Urea concentration tended to be higher and non-esterified fatty acids lower in blood from heifers offered the diet containing untreated casein, but these differences were not statistically significant. Blood glucose concentration was not affected by dietary treatment.

5. It was concluded that blood GH concentration can be increased by offering protein supplements which will increase total amino acid supply to the intestines in lactating cattle. This appears to be a direct effect on GH status independent of effects on milk yield.
What sort of teenager has high intakes of energy and nutrients?
Authors: Woodward David R.
Published: May 2005

1. An alternative statistical technique, based on analysis of the 75th percentile, was used to examine teenagers' diets. The technique was developed to identify personal characteristics that affected the prevalence of high energy and nutrient intakes. It provided useful information not obtainable from methods based on average intakes.

2. The study sample was a representative sample of 1055 high-school students in Tasmania, Australia, aged 11–16 years.

3. Among girls, the prevalence of high intakes of energy and several nutrients was not affected by any of the fifteen characteristics studied. (In this context, ‘high’ was defined as above the 75th percentile for girls.) Fatter, heavier girls were less likely to have high intakes of carbohydrate, iron and niacin-equivalent, and also of meat and ‘empty-energy’ foods. Girls from small families were less likely to have high calcium intakes, and girls from goverment schools less likely to have high thiamin intakes.

4. Among boys, age generally had the greatest influence on the prevalence of high intakes (‘high’ being defined as above the 75th percentile for boys). Older boys were more likely to have high intakes of energy and most nutrients, as well as meat, cereals and fruit and vegetables. These age-related changes were, however, rather asynchronous. High fat intakes were more common among boys wbo had drunk more than five glasses of alcoholic beverages in the preceding week. High Ca intakes were more frequent among those who exercised vigorously, and high vitamin A intakes less common among the sons of well-educated mothers.
The impact of adjustment of a weight-height index (W/H2) for frame size on the prediction of body fatness
Authors: Rookus Maartje A. , Burema Jan , Deurenberg Paul , Van Der Wiel-Wetzels Wilhelmina A. M.
Published: May 2005

1. The impact of frame-size categories in weight-height tables was studied by comparing the efficiency of the body-mass index (weight/height2 (W/H2)) and weight adjusted for body-height and a body-diameter, W/(H2Dp), in predicting body fatness.

2. Body-weight, body-height, six body-diameters and four skinfold thicknesses were measured in ninety-five men and seventy women, aged between 23 and 35 years. Percentage of body fat was calculated from skinfold thicknesses using regression equations according to Durnin & Womersley (1974).

3. The inclusion of a body-diameter increased the explained variation of body fatness from 57% to 62% (knee) and 63% (shoulder) in men and from 63% to 69% (knee) in women.

4. It can be concluded that in the present population the efficiency of the prediction of percentage of body fat was not improved markedly by the inclusion of a body-diameter in the body-mass index, thus giving no support for the inclusion of frame-size categories in weight-height tables.
Net protein utilization determined by rat bioassay of a protein hydrolysate and a diet for children with phenylketonuria
Authors: Kindt Elisabeth , Holm Halvor , Halvorsen Sverre , Lie Sverre O.
Published: May 2005

1. In a previous study (Kindt et al. 1983, 1984) it was assumed that a protein hydrolysate, devoid of phenylalanine, together with intact protein as given to children with phenylketonuria (PKU), was equivalent to egg or milk protein. One group of children was given this ‘PKU protein’ in amounts corresponding to the Joint FAO/WHO ad hoc Expert Committee (1973) recommendations. The results indicated that the Joint FAO/WHO ad hoc Expert Committee (1973) recommended levels of protein intake were marginal.

2. The purpose of the present study was to evaluate whether the quality of the protein hydrolysate, together with intact protein (‘PKU protein’), is equivalent to egg or milk protein. This was done using a rat bioassay. Four protein sources were used: (1) egg protein, (2) protein hydrolysate, (3) protein hydrolysate diluted with non-essential amino acids, (4) protein hydrolysate mixed with food proteins (‘PKU protein’), comparable with the diet previously used (Kindt et al. 1983, 1984).

3. The results indicated that the ‘PKU protein’ was of very high qua1ity: net protein utilization (NPU) > 90. The protein hydrolysate alone and the protein hydrolysate diluted with non-essential amino acids gave a NPU > 80.

4. The conclusion drawn from the present study is that the ‘PKU protein’, as used in the treatment of children with PKU, is equivalent to egg or milk protein. This supported the view that the Joint FAO/WHO ad hoc Expert Committee (1973) recommended levels of intake were marginal.
Family food purchases and home food consumption: comparison of nutrient contents
Authors: Nelson M. , Dyson P. A. , Paul A. A.
Published: May 2005

1. Estimates of nutrient intakes based on food purchasing records modelled on the National Food Survey (NFS) were compared with nutrient intakes calculated from food consumption records based on a semi-weighed method, a combination of weighing and household measurement techniques. Of eighty-two families in Cambridge who completed the study, thirty-two were volunteers and fifty were from a random sample in which the co-operation rate was 73%.

2. The estimated energy and nutrient contents of the Cambridge food purchases were very similar to those reported by the NFS for families of similar composition and income. The energy intakes obtained by the semi-weighed method were compared with results from twenty-five studies of energy intake based on quantitative measurements of food consumption: there was no evidence to suggest that the semi-weighed method consistently under- or overestimated intakes in the Cambridge subjects.

3. Purchases adjusted to allow for waste and consumption of food by visitors contained significantly more energy, protein, carbohydrate, calcium, iron and dietary fibre than measured home food consumption. There was no significant difference in the nutrient content of purchases and consumption per 4.184 MJ (1000 kcal), with the exception of Fe and ascorbic acid.

4. Measured wastage of edible food in thirty-one families averaged 3.2% of purchases. Estimate of wastage in all eighty-two families was 3.8%, and consumption of food by visitors accounted for 3.0% of purchases.

5. The excess of purchases over measured home food energy intake is probably accounted for by a net increase in larder stocks rather than wastage, consumption of food by visitors, or under-recording of intakes.
Studies of zinc metabolism in pregnant and lactating rats
Authors: Fairweather-Tait Susan J. , Wright A. J. A. , Cooke Jacqui , Franklin J.
Published: May 2005

1. The metabolism of 65Zn administered intramuscularly (Expt 1) or enterally (Expt 2) at the beginning of pregnancy in rats given a control or marginal-Zn diet was measured. In Expt 2 a comparison was also made between pregnant and non-pregnant rats. The loss of 65Zn (assumed to represent labile body Zn) was markedly reduced in animals fed on a marginal-Zn diet compared with controls, and this effect occurred very rapidly, i.e. within 48 h of introducing the marginal-Zn diet. Pregnancy itself had a much less important effect on 65Zn turnover than diet. Transfer of 65Zn to the litter was significantly greater in the animals fed on a marginal-Zn diet compared with controls but total Zn transfer was reduced.

2. The effect of length of time on a marginal-Zn diet on fetal growth and composition was examined. Compared with controls, fetal weight was significantly greater in litters from mothers fed on a marginal-Zn diet during the last 4, 7 or 14 d of pregnancy, but no different in litters from mothers fed on a marginal-Zn diet throughout pregnancy. There were no differences in the proportions of protein or fat in the fetuses from mothers fed on the control or marginal-Zn diets but the Zn concentration was lower in litters from mothers fed on a marginal-Zn diet during part or ail of the pregnancy when compared with controls.

3. The transfer of 65Zn from mothers to litters during birth and the first 3 d of lactation was measured. There were no differences in maternal or litter 65Zn just before or just after birth, but within 72 h maternal 65Zn had significantly decreased and litter 65Zn increased. Increases in litter size were associated with greater total litter 65Zn but reduced individual fetal 65Zn.

4. These experiments demonstrate the importance of an adequate daily supply of Zn during pregnancy. Although there is room for adaptation to a marginal-Zn intake (by reducing Zn excretion) the maintenance of Zn homeostasis is only possible in the absence of other forms of stress, such as pregnancy, to the body. The consequence of insufficient Zn at times of rapid fetal growth on carbohydrate and lipid metabolism warrants further investigation.
The effect of dietary bagasse on the activities of some key enzymes of carbohydrate and lipid metabolism in mouse liver
Authors: Stanley John C. , Newsholme Eric A.
Published: May 2005

1. The effects of a 100 g/kg diet substitution of bagasse on the body-weight gain, food consumption and faecal dry weight of mice given a high-sucrose diet and on the activities of hepatic glucose-6-phosphate dehydrogenase (EC1. 1. 1. 49), 6-phosphogluconate dehydrogenase (ECI. I. I. 44), malate dehydrogenase (oxaloacetatedecarboxylating) (NADP+) (ECI. I. I. 40), ATP-citrate (pro-3S) lyase (EC4. 1. 3.8), 6-phosphofructokinase (EC2. 7. 1. II), pyruvate kinase (EC2.7. 1. 40) and fructose-1,6-bisphosphatase (EC3. 1. 3. II) were studied.

2. Bagasse had no effect on body-weight gain, food consumption or faecal dry weight.

3. Bagasse decreased the activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and phosphofructokinase expressed on a wet weight basis and on a protein basis.

4. Bagasse decreased the activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydro-genase expressed on a body-weight basis.

5. These results suggest that bagasse decreases the flux through some pathways of hepatic lipogenesis when mice are given high-sucrose diets.
Experimental zinc deficiency in guinea-pigs: clinical signs and some haematological studies
Authors: Gupta R. P. , Verma P. C. , Gupta R. K. Paul
Published: May 2005

1. Thirty-three male, weanling guinea-pigs were divided into two groups. One group was fed on a zinc-deficient (ZnD) diet (1.25 mg Zn/kg diet) for 45 d and then divided into two subgroups: subgroup 1 continued on diet ZnD while subgroup 2 was fed on a Zn-repleted diet (100 mg Zn/kg diet) for 15 d. The second group was fed on a Zn-adequate diet (50 mg Zn/kg diet) for 60 d.

2. Zn deficiency could be produced within 21 d as evidenced by clinical signs and reduction in serum Zn concentration.

3. Clinical signs exhibited were listlessness, scabby lesions on skin near the foot pads, mild alopecia and a reduction in body-weight gain. No effect was observed on food intake.

4. Significant decreases in packed cell volume and total leucocyte count from 48 d onwards accompanied by absolute lymphocytopenia and relative neutrophilia were observed.

5. Supplementation of Zn in the Zn-repleted group resulted in marked, though incomplete, improvement with regard to serum Zn concentration, clinical signs and haematological changes.
A comparative study of phytate hydrolysis in the gastrointestinal tract of the golden hamster (Mesocricetus auratus) and the laboratory rat
Authors: Williams P. J. , Taylor T. G.
Published: May 2005

1. The role of bacterial, dietary and intestinal phytases (EC 3. 1. 3. 8) in the hydrolysis of phytate was investigated in the golden hamster and rat by assaying phytase in the small intestine and by measuring the disappearance of phytate from the stomach and large intestine, using chromium oxide as an insoluble solid-phase marker.

2. It was confirmed that an active phytase was present in the proximal third of the small intestine of the rat but the enzyme was undetectable in the hamster.

3. Extensive bacterial breakdown of phytate occurred in the pregastric pouch and true stomach of the hamster with both phytase-containing and phytase-free diets, with phytate digestibilities in the true stomach ranging from 0.69–0.90, confirming that the hamster can be regarded as a pseudo-ruminant.

4. With a phytase-free diet, the digestibility of phytate in the stomach of the rat was very low (0.05) but with a wheat-based diet substantial breakdown of phytate occurred (digestibility up to 0.49), presumably under the influence of the cereal phytase.

5. Intestinal phytase did not appear to be of great significance in the rat but some further hydrolysis of the residual phytate probably occurred in the large intestine of both species by bacterial phytase.
Insulin action and glucose metabolism in sheep fed on dried-grass or ground, maize-based diets
Authors: Janes A. N. , Weekes T. E. C. , Armstrong D. G.
Published: May 2005

1. The effect of an exogenous supply of glucose, provided by the digestion of maize starch in the small intestine, on endogenous glucose metabolism and insulin action was studied in sheep using the euglycaemic insulin clamp procedure.

2. Insulin was infused intravenously at rates of 0.2, 0.5, 1.0 and 6.0 mU/min per kg live weight for four consecutive periods in each of four sheep fed on dried-grass and maize-based diets. Glucose was also infused intravenously at a variable rate, sufficient to maintain the plasma glucose concentration at basal levels. Whole-body rates of glucose metabolism were determined using a continuous infusion of [6-3H]glucose.

3. From the resultinginsulin dose-response curves, it was observed that, when the sheep were fed on the dried-grass diet, the responsiveness of glucose metabolism to insulin was less than that reported for non-ruminants.

4. When fed the maize-based diet, the glucose metabolic clearance rates (MCR) observed during insulin infusions were significantly greater (P < 0.05) than those observed for the dried-grass diet. However, after correcting for the non-insulin-mediated glucose disposal, differences between diets were not significant.

5. The sensitivity of glucose utilization to insulin was not affected by diet. The plasma insulin concentrations causing half-maximal insulin-mediated glucose MCR were 103 (SE 21) and 85 (SE 11) mU/l for the dried-grass and maize-based diets respectively.

6. The sensitivity of endogenous glucose production to insulin was also unaffected by diet. The plasma insulin concentrations resulting in the suppression of endogenous glucose production to half the basal level were 80 (SE 26) and 89 (SE 29) mU/l for the dried-grass and maize-based diets respectively.

7. It is concluded that the observed increase in glucose utilization on the maize-based diet was due partly to a slight change in responsiveness to insulin and also partly to a change in the rate of non-insulin-mediated glucose disposal.
Estimation of microbial nitrogen in nylon-bag residues by feed15N dilution
Authors: Varvikko T. , Lindberg J. E.
Published: May 2005

1. Rapeseed (Brussicu nupus), barley grain, ryegrass (Loliurnperenne) and barley straw were labelled with15N as an internal marker. The dilution of15N was used to estimate microbial N (RMN15N) in the feed residues in nylon bags incubated in the rumen for 5, 12 and 24 h. For comparative purposes, diaminopimelic acid (DAP) content of the residues was also determined and rumen microbial N (RMNDAP-N) in the feed residues calculated using DAP as a bacterial marker. The influence of two bag pore sizes (20 μm and 40 μm) with different sample sizes (1 g and 5 g respectively) was also studied.

2. For all feeds, the average disappearance of15N was faster than that of total N, the difference between N and15N disappearance being marked with barley, ryegrass and barley straw. The disappearance of microbially corrected dry matter (DM; correction calculated from the15N values) was, accordingly, always faster than the uncorrected DM disappearance. Except for the bag pore/sample size effect for N disappearance, significant (P < 0.01–0.001) feed, pore/sample size and incubation-time effects were always found for the disappearance values.

3. Errors (%) resulting from the microbial contamination (calculated from the15N values) in N-loss measurement with rapeseed, barley, ryegrass and barley straw, at 5, 12 and 24 h in 20 μm bags were respectively: –1.8, –3.9, –0.9; –3.8, –22.4, –3.8; –7.2, –4.1, –2.9; –164.5, –146.3, –204.6. In 40 μm bags the corresponding errors were respectively: –4.4, –1.2, –0.7; –26.1, –10.5, –3.9; –13.2, –6.4, –5.5; –221.2, –310.1, –1284.6.

4. The largest residual proportions of RMN15N, RMNDAP-Nand DAP-N (% of total N) were found in barley straw, followed by barley, ryegrass and rapeseed, in that order. RMN15N(g/kg residual DM) followed the descending order: barley, ryegrass, straw, rapeseed. RMNDAP-N, (g/kg residual DM) and DAP (mg/kg residual DM) followed the descending order: barley, ryegrass, rapeseed and barley straw. Feed, pore/sample size and incubation-time effects were always significant (P < 0.001).

5. With 40 μm bags RMN15Nvalues of barley, ryegrass and barley straw (expressed as % of total N or g/kg residual DM) were substantially higher than those of RMNDAP-NWith 20 μm bags the RMN15Nand RMNDAP-Nvalues were generally quite close for these feeds. With rapeseed residues, RMN15Nwas clearly lower than RMNDAP-Nwith 20 μm bags, but only small differences were found with 40 μm bags.

6. A more diverse microbial colonization of feed samples was indicated in the 40 μm bags compared with the 20 μm bags. It was also noticed, consequently, that in most cases larger error resulted from the microbial contamination in 40 μm bags.
Biotin deficiency and susceptibility to fatty liver and kidney syndrome in broiler chicks: reduced 6-phosphofructokinase (EC2.7.1.11) activity but normal fructose 2,6-bisphosphate content in birds with hepatomegaly
Authors: Bannister D. W. , Sales D. I. , Lee Alison
Published: May 2005

1. In two separate experiments, using different strains, broiler chicks were reared on either a commercial-type chick mash (control) or a fatty liver and kidney syndrome (FLKS)-inducing diet.

2. In Expt a, chicks were killed on day 29 and in Expt b, on day 32. Body-weights and liver weights were measured, and values from those given the control ration used to construct a hepatomegaly index by employing a variant of linear discriminant analysis.

3. Application of the index to FLKS birds revealed a statistically significant bimodal distribution of liver size.

4. The birds with enlarged livers (high index) also possessed metabolic abnormalities in that 6- phosphofructokinase (EC2. 7. 1. 11; PFK-1) activity (measured at low substrate concentration) was depressed despite the presence of normal, or even slightly elevated fructose 2,6-bisphosphate concentration.

5. This indicates the presence of an uncharacterized regulatory mechanism for PFK- 1 in FLKS-susceptible birds.
Estimation of the degradability of dietary protein in the sheep rumen by in vivo and in vitro procedures
Authors: Siddons R. C , Paradine J , Gale D. L. , Evans R. T.
Published: May 2005

1. Estimates of degradability of nitrogen in the sheep rumen for a basal hay diet and for soya-bean meal (SBM), groundnut meal (GNM) and fish meal (FM), when given together with the hay, were determined from measurements of (1) duodenal N flow, (2) ammonia kinetics and (3) rumen N disappearance from polyester bags and rumen outflow rate. The ability of various in vitro procedures to predict in vivo N degradability was also examined.

2. Four sheep were given a basal hay diet (800 g dry matter (DM) and 19 g N/d) either alone or supplemented with isonitrogenous amounts (15 g N/d) of SBM, GNM or FM. Duodenal non-ammonia-N flow (g/d) was increased more by FM (8.0) than by GNM (5.9) and SBM (5.8), whilst microbial N flow (g/d) was increased more by SBM (3.9) than by GNM (2.3) and FM (1.6). N degradability values calculated from these results were 0.88, 0.76 and 0.57 for the SBM, GNM and FM respectively. The corresponding value for hay was calculated to be 0.76.

3. The irreversible loss of ammonia in the forestomachs (g N/d) was increased more by SBM (11.9) than by GNM (7.2) and FM (5.8) whilst ammonia outflow from the rumen (g N/d) was increased to a similar extent by all supplements ( I.1, 0.9 and 0.8 respectively), as was the amount of microbial N (g/d) synthesized from sources other than rumen ammonia (1.8, 2.0 and 1.9 respectively). N degradability values calculated from these results were 0.84, 0.54 and 0.45 for the SBM, GNM and FM respectively.

4. The fractional rate of N disappearance (/h) when the feedstuffs were incubated in polyester bags in the rumen of sheep receiving the basal hay diet (800 g DM/d) was the highest for SBM (0,145) and lowest for FM (0.037), with the hay (0.082) and GNM (0.071) intermediate, whilst the fractional outflow rates from the rumen (/h) of the three supplements were similar (0.034, 0.038 and 0,030 for SBM, GNM and FM espectively). N degradability values calculated from these results were 0.82, 0.67 and 0.60 for the SBM, GNM and FM respectively; the value for the hay was 0.73.

5. Of a number of in vitro procedures tested, only N solubility in sodium hydroxide and ammonia or total non-protein-N (NPN) production during incubation with rumen fluid in the absence of hydrazine sulphate ranked the supplements, although not the hay, in the same order as the in vivo degradability procedures. In terms of absolute values, N solubility in NaOH, at room temperature, gave estimates similar to those derived from the duodenal flow measurements; estimates derived from ammonia and total NPN production were lower.
Characterization of an infectious clone of the wild-type yellow fever virus Asibi strain that is able to infect and disseminate in mosquitoes
Authors: McElroy Kate L. , Tsetsarkin Konstantin A. , Vanlandingham Dana L. , Higgs Stephen
Published: May 2005

Infectious clone technology provides an opportunity to study the molecular basis of arthropod–virus interactions in detail. This study describes the development of an infectious clone of the prototype yellow fever virus Asibi strain (YFV-As) with the purpose of identifying sequences or domains that influence infection dynamics in the mosquito vector. The full-length cDNA of YFV-As virus was produced from RT-PCR products of parental viral RNA. These were cloned into a low-copy-number plasmid previously used to develop the YFV-17D infectious clone (pACNR/FLYF-17D). Virus recovered from the infectious clone exhibited biological characteristics similar to those of the parental YFV-As, including replication kinetics, reactivity to flavivirus cross-reactive and YFV-specific antibodies and infection and dissemination rates in Aedes aegypti, the principal mosquito vector of YFV. These data provide the basis for future studies with chimeric Asibi/17D viruses to identify the determinants of vaccine attenuation in the vector.
Complete genome sequence of simian adenovirus 1: an Old World monkey adenovirus with two fiber genes
Authors: Kovács Gábor M. , Harrach Balázs , Zakhartchouk Alexander N. , Davison Andrew J.
Published: May 2005

Simian adenovirus 1 (SAdV-1) is one of many adenovirus strains that were isolated from Old World monkey cells during poliomyelitis vaccine production several decades ago. Despite the availability of these viruses, knowledge of their genetic content and phylogeny is rudimentary. In the present study, the genome sequence of SAdV-1 (34 450 bp) was determined and analysed. In regions where genetic content varies between primate adenoviruses, SAdV-1 has a single virus-associated RNA gene, six genes in each of the E3 and E4 regions and two fiber genes. SAdV-1 clusters phylogenetically with HAdV-40, a member of human adenovirus species HAdV-F, which also has two fiber genes. However, based on phylogenetic distances and other taxonomic criteria, SAdV-1 is proposed to represent a novel adenovirus species.
Susceptibility of B lymphocytes to adenovirus type 5 infection is dependent upon both coxsackie–adenovirus receptor and αvβ5 integrin expression
Authors: Richardson Ciarán , Brennan Paul , Powell Martin , Prince Stuart , Chen Yun-Hsiang , Spiller O. Brad , Rowe Martin
Published: May 2005

Human lymphocytes are resistant to genetic modification, particularly from recombinant adenoviruses, thus hampering the analysis of gene function using adenoviral vectors. This study engineered an Epstein–Barr virus-transformed B-lymphoblastoid cell line permissive to adenovirus infection and elucidated key roles for both the coxsackie–adenovirus receptor and αvβ5 integrin in mediating entry of adenoviruses into these cells. The work identified a strategy for engineering B cells to become susceptible to adenovirus infection and showed that such a strategy could be useful for the introduction of genes to alter lymphoblastoid-cell gene expression.
A quasi-monoclonal anti-HBs response can lead to immune escape of ‘wild-type’ hepatitis B virus
Authors: Margeridon Séverine , Lachaux Alain , Trepo Christian , Zoulim Fabien , Kay Alan
Published: May 2005

Hepatitis B virus (HBV) infections can be prevented or controlled by the host humoral immune response (anti-HBs) directed against the major surface antigen (HBsAg), elicited either naturally or by vaccination. A chronic HBV carrier was found to have high levels of both virus and anti-HBs. Full-length HBV genomes were amplified from the patient's serum, sequenced and cloned. The genome was ‘wild-type’ HBV of genotype C and serotypeadr. The sequence has remained stable, with no signs of emergence of an immune-escape mutant population. To study what was recognized by the patient's serum, viral particles were35S-labelled and then immunoprecipitated by using the patient's serum or control sera. The patient's serum immunoprecipitated theadrHBsAg encoded by his HBV genome poorly, but efficiently recognized HBsAg of serotypeayw. When his HBV genome was modified by a point mutation to express HBsAg of serotypeayr, the patient's serum could recognize the antigen, as well as the control anti-HBs-positive serum. The patient appeared to have made a quasi-monoclonal humoral response to theyepitope. By switching to thedepitope, which requires only a point mutation, the virus could replicate, despite the high levels of anti-HBs. This study underlines the subtleties of virus–host interactions. Implications for HBV vaccination are discussed.
Analysis of a 17-amino acid residue, virus-neutralizing microantibody
Authors: Heap Caroline J. , Wang Yuqin , Pinheiro Teresa J. T. , Reading Steven A. , Jennings Keith R. , Dimmock Nigel J.
Published: May 2005

The antibody-binding site, through which an antibody binds to its epitope, is a complex structure formed by the folding together of six complementarity-determining regions (CDRs). However, certain peptides derived from CDR sequences retain antibody specificity and function; these are know as microantibodies (MicroAbs). For example, the F58 MicroAb is a 17 residue, cyclized peptide (CDLIYYDYEEDYYFDYC) derived from CDR-H3 of F58, an IgG1 specific for the gp120 envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1). Both MicroAb and IgG recognize the same epitope in the V3 loop and, despite its small size, the MicroAb neutralizes the infectivity of HIV-1 IIIB only 32-fold less efficiently on a molar basis. The advantage of MicroAbs is that their small size facilitates structure–function analysis. Here, the F58 MicroAb was investigated using alanine scanning, mass spectroscopy and surface plasmon resonance. Neutralization of infectious IIIB was generally more sensitive to alanine substitution than binding to soluble gp120. There appeared to be a division of function within the MicroAb, with some residues involved in antigen binding (alanine substitution of 11D, 12Y or 13Y abrogated both binding and neutralization), whereas others were concerned solely with neutralization (substitution of 3L, 8Y or 14F abrogated neutralization, but not binding). The MicroAb is predominantlyβ-sheet and has strong conformational constraints that are probably essential for activity. The MicroAb and soluble gp120 formed a 1 : 1 complex, with an association rate that was threefold greater than that with IgG and a faster dissociation rate. Its equilibrium dissociation constant is 37·5-fold greater than that of IgG, in line with neutralization data. This study demonstrates how MicroAbs can make a useful contribution to the understanding of antigen–antibody interactions.
Wild-type Rinderpest virus uses SLAM (CD150) as its receptor
Authors: Baron Michael D.
Published: May 2005

Rinderpest virus (RPV) is a morbillivirus, related closely to the human pathogen Measles virus (MV). Although cell culture-adapted strains of RPV can infect many kinds of cell from different hosts, one such strain has previously been shown to have a detectable preference for cells expressing the MV receptor CD150 (SLAM), a protein found only on certain types of activated T cells, B cells and dendritic cells. Here, it is shown that the wild-type, virulent parent of the most common vaccine strain of RPV requires CD150 as a receptor, whilst the cell culture-adapted vaccine strain has acquired the ability to use heparan sulphate as an alternative receptor.
African origin of GB virus C determined by phylogenetic analysis of a complete genotype 5 genome from South Africa
Authors: Muerhoff A. Scott , Leary Thomas P. , Sathar Mahomed A. , Dawson George J. , Desai Suresh M.
Published: May 2005

GB virus C (GBV-C), a positive-strand RNA virus, currently infects approximately one-sixth of the world's population. This virus exists as a collection of genotypes whose global distribution correlates with geographical origin. Genotyping of GBV-C isolates by phylogenetic analysis has relied upon the use of 5′-untranslated region (5′-UTR) sequences, however, complete genome sequences are used to demonstrate definitively their existence and geographical correlation. Initial identification of the fifth genotype from South Africa was based upon phylogenetic analysis of the 5′-UTR. It was sought to confirm this classification by analysis of full-length E2 genes from South African isolates and by analysis of a complete genotype 5 genome. Analysis of full-length E2 genes from 28 GBV-C-infected South African individuals revealed the existence of a unique group of 18 isolates, distinct from the other four genotypes. Bootstrap analysis provided strong support (95 %) for this fifth group. The remaining isolates were either genotype 1 (n=8) or 2 (n=2). Analysis of human E2 gene sequences, with the E2 gene from the chimpanzee variant GBV-Ctro included as the outgroup, produced a tree rooted on the genotype 1 branch. The complete genome nucleotide sequence of South African genotype 5 isolate D50 was determined. Phylogenetic analysis of the 5′-UTR and open reading frame produced congruent trees that grouped the sequences into five major genotypes. Inclusion of the corresponding region of the chimpanzee isolate GBV-Ctro in the analysis produced trees rooted on the branch leading to the genotype 5 isolate D50, suggesting an ancient African origin of GBV-C.
The GP64 protein of Autographa californica multiple nucleopolyhedrovirus rescues Helicoverpa armigera nucleopolyhedrovirus transduction in mammalian cells
Authors: Liang Changyong , Song Jianhua , Chen Xinwen
Published: May 2005

Autographa californica multiple nucleopolyhedrovirus (AcMNPV) belonging to the group I nucleopolyhedroviruses (NPVs) and expressing the envelope-fusion glycoprotein GP64 transduces a variety of mammalian cells to express foreign genes under the control of mammalian promoters. In contrast, the group II Helicoverpa armigera single NPV (HaSNPV) encoding a different envelope protein, the F protein, shows no detectable infectivity towards mammalian cells. This limitation was overcome by expressing AcMNPV GP64 in HaSNPV. Although the transduction ratios were lower overall, the range of mammalian cell types transduced by HaSNPV was consistent with those transduced by AcMNPV. These findings indicate that the F protein functions only in insect cells, whereas the GP64 protein works in both insect and mammalian cells.
Mutational analysis does not support the existence of a putative tertiary structural element in the left terminal domain of Potato spindle tuber viroid
Authors: Owens Robert A. , Thompson Susan M.
Published: May 2005

Comparative sequence analysis suggests that the left terminal domain of Potato spindle tuber viroid (PSTVd) and other large pospiviroids may assume a branched tertiary structure containing two pseudoknots. To search for evidence of such a structure in vivo, the nucleotide sequences proposed to interact were mutagenized, tomato seedlings were inoculated with mixtures of potentially infectious PSTVd RNA transcripts and the resulting progeny were screened for compensatory sequence changes. Positions 6–11 and 330–335 tolerated only limited sequence variation, and compensatory changes consistent with formation of an intact pseudoknot were observed in only two of the plants examined. No variation was detected at positions 14–16 or 29–31. Passage of selected variants in Rutgers tomato led to an increase in virulence only upon reversion to wild-type PSTVd_Intermediate. The ability of the left terminal domain to assume a branched conformation containing pseudoknots does not appear to be an important determinant of PSTVd fitness.
The adenovirus capsid: major progress in minor proteins
Authors: Vellinga Jort , Van der Heijdt Stephanie , Hoeben Rob C.
Published: May 2005

Human adenoviruses have been the subject of intensive investigation since their discovery in the early 1950s: they have served as model pathogens, as probes for studying cellular processes and, more recently, as efficient gene-delivery vehicles for experimental gene therapy. As a result, a detailed insight into many aspects of adenovirus biology is now available. The capsid proteins and in particular the hexon, penton-base and fibre proteins (the so-called major capsid proteins) have been studied extensively and their structure and function in the virus capsid are now well-defined. On the other hand, the minor proteins in the viral capsid, i.e. proteins IIIa, VI, VIII and IX, have received much less attention. Only the last few years have witnessed a sharp increase in the number of studies on their structure and function. Here, a review of the minor capsid proteins is provided, with a focus on new insights into their position and role in the capsid and the opportunities that they provide for improving human adenovirus-derived gene-delivery vectors.