bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of diets containing casein and rapeseed on enzyme secretion from the exocrine pancreas in the pig
Authors: Valette P. , Malouin H. , Corring T. , Savoie L. , Gueugneau A. M. , Berot S.
Published: May 2005

The effect of dietary protein on enzyme activity of pancreatic juice was studied in ten growing, castrated, Large White male pigs. Animals, fitted with permanent cannulas in the pancreatic duct and in the duodenum, were divided into two groups receiving either casein or rapeseed concentrate as a protein source. After a 15 d adaptation period to the experimental diet, the volume of pancreatic secretion was significantly higher, whereas the protein concentration was lower in the casein group compared with the rapeseed group. No statistical difference was observed in the daily protein output between groups. Total secreted activities of carboxypeptidase A (EC3.4.17.1), and elastase (EC3.4.21.36) were higher in the casein group during the nocturnal period, whereas total activities of trypsin (EC3.4.21.4), chymotrypsin (EC3.4.21.1), carboxypeptidase B (EC3.4.17.2) and amylase (EC3.2.1.1) in pancreatic secretions during the post-prandial periods were increased by the ingestion of the rapeseed diet. It is concluded that the pancreatic enzyme secretion is sensitive to the nature of the protein ingested.
Inhibitory effect of high protein intake on nephrocalcinogenesis in female rats
Authors: Sterck J. G. H. , Ritskes-Hoitinga J. , Beynen A. C.
Published: May 2005

Increased intakes of protein have been shown to reduce kidney calcification (nephrocalcinosis) in female rats. Two questions were addressed in the present study. First, can protein-induced inhibition of nephrocalcinosis be demonstrated when the diets used are balanced for calcium, magnesium and phosphorus in the added protein? Second, can the protein effect be explained by the frequently observed magnesiuria after giving high-protein diets? Nephrocalcinosis was induced in female rats by giving purified diets containing 151 g casein/kg and either an increased concentration of P (6v.2 g/kg) or a decreased concentration of Mg (0·1v.0·4 g/kg). To these diets 151 g ovalbumin/kg was added at the expense of glucose, and the diets were balanced for Ca, Mg and P in ovalbumin. The diets were given for 29 d. In rats fed on the diet containing 151 g protein/kg, an increased intake of P or a decreased intake of Mg caused nephrocalcinosis as measured chemically by analysis of kidney Ca as well as histologically by scoring kidney sections stained according to Von Kossa's method. The addition of ovalbumin to the diet prevented the induction of nephrocalcinosis. High P intake and low Mg intake with the low-protein diets induced enhanced loss of albumin in urine, suggesting that nephrocalcinosis caused kidney damage. Increased protein intake with a non-calcinogenic diet also caused increased albumin excretion in urine. Irrespective of the composition of the background diet, increased protein intake caused increased urinary excretion of Mg. When all dietary groups were considered, differences in nephrocalcinosis and urinary Mg output were not proportionally related.

Nephrocalcinosis: Phosphorus: Magnesium: Protein: Rat
Effect of dietary proteins on insulin-like growth factor-1 (IGF-1) messenger ribonucleic acid content in rat liver
Authors: Miura Yutaka , Kato Hisanori , Noguchi Tadashi
Published: May 2005

Effects of quantity and quality of dietary proteins on plasma immunoreactive insulin-like growth factor-1 (IGF-1) concentration, and content of IGF-1 mRNA in rat liver were investigated in rats. Plasma immunoreactive IGF-1 concentration in rats given a casein diet was higher than that in rats given a soya-bean-protein or protein-free diet. The IGF-1 mRNA content in liver was estimated by the Northern blot hybridization technique employing32P-labelled rat IGF-1 complementary DNA (cDNA). At least four molecular species of IGF-1 mRNA of different molecular weight were found in rat liver. The sizes were 0·8–1·2, 2·0, 3·6–4·0 and 7·4 kb. Most of the mRNA species decreased in the livers of rats given a gluten diet (120 g gluten/kg diet) compared with rats given the casein diet. In particular, mRNA of 7·4 kb decreased markedly. When rats were fed on the protein-free diet, mRNA of all species decreased significantly. The estimated IGF-1 mRNA in the livers of rats fed on the gluten or protein-free diet was almost 0·4 of that of the rats given the casein diet. Feeding the soya-bean-protein diet did not result in a marked effect on the hepatic content of mRNA species of IGF-1. The results showed that liver IGF-1 mRNA content is sensitively regulated by quantity and nutritional quality of dietary proteins.
The effect of malnutrition on insulin binding to rat erythrocytes
Authors: Payne-Robinson Hazel M. , Brown Richard
Published: May 2005

Insulin binding to erythrocyte receptors was compared in malnourished and control rats. Percentage specific insulin binding to malnourished rat erythrocytes was significantly lower than to control erythrocytes (P< 0.001). The low insulin binding in the malnourished rat erythrocytes was accompanied by low insulin receptor affinity (P= 0.035).
Supplementation with wheat selenium induces a dose-dependent response in serum and urine of a Se-replete population
Authors: Meltzer Helle M. , Norheim Gunnar , LØken Elin BjØRge , Holm Halvor
Published: May 2005

In spite of a rather modest dietary intake of selenium (80 μg/10 MJ), Norwegian serum Se levels are among the highest in Europe. As part of an ongoing study of Se bioavailability, effects of different doses of wheat Se were investigated in eighteen healthy, Norwegian women. The participants were given Se-rich bread providing 100, 200 and 300 μg Se daily for 6 weeks. About 50% of the Se intake was excreted in the urine by week 6, compared with 67% before the intervention started. Serum Se increased by 20, 37 and 53 μg/I respectively, in the three groups (P< 0.001). The blood response and renal clearance results compare well with data obtained from less Se-replete populations, and support the hypothesis that selenomethionine from the diet is incorporated into a non-specific amino acid pool. Our study indicates that the intake of wheat Se is the main determinant of blood Se levels in Norway.
Mineral excretion of rats fed on diets containing faba beans (Vicia faba L.) or faba bean fractions
Authors: Rubio Luis A. , Grant George , Bardocz Susan , Dewey Peter , Pusztai A.
Published: May 2005

The effects on faecal mineral excretion of two commercial varieties (local cultivar and Troy cultivar) of raw faba beans (Vicia faba L., minor) meal (VFM) and its fractions have been studied in growing rats. Diets contained local-VFM (dark seed coat) and Troy-VFM (light seed coat) at 474–500 g/kg diet, hull (VFH) from both varieties at 65 g/kg diet, and the insoluble cotyledon residue (VFCR) obtained from the Troy variety at 237 g/kg diet. Rats were pair-fed on diets which had been supplemented with amino acids to target requirements and contained similar amounts of zinc, manganese, iron and copper. With VFM diets the apparent absorption of Zn and Mn was significantly reduced. On the other hand, with hulls the apparent absorption of Fe was reduced while that of Cu slightly increased. As the amounts of calcium, phosphorus and magnesium in VFM and VFH diets were higher than in the controls, the increased intake resulted in a significant increase in both the apparent absorption and the faecal excretion of these minerals. The inclusion of VFCR in the diet had no significant effect on the mineral content of faeces. The relatively low concentrations of phytate in the bean seeds of 7.8 and 6.7 g/kg for the local and Troy cultivars respectively, could not adequately account for the increased mineral excretion. The results suggest that other seed constituents, possibly the soluble non-starch polysaccharides, may be involved in the elevated loss of Zn and Mn in rats fed on diets containing faba bean for extended periods, while some insoluble structural hull components may interfere with the absorption of Fe from the gut.

Faba bean (Vicia faba): Faecal mineral excretion: Rat.
Studies of method of conserving grass herbage and frequency of feeding in cattle
Authors: Thiago L. R. L. , Gill M. , Dhanoa M. S.
Published: May 2005

The effect of method of conserving grass herbage and the frequency of feeding on digestion in and passage from the rumen was studied in growing cattle. A single sward of perennial ryegrass (Lolium perennecv. Endura) was cut on 1 d and conserved as silage or hay. These forages were offered as the only feed to twelve rumen-cannulated Friesian steers (average initial live weight (LW) 128 kg) either at a restricted level of intake (20 g dry matter (DM)/kg LW; Expt 1) orad lib.(Expt 2). In Expt 1 the forages were offered either once or eight times daily. When fed once or eight times daily, in vivo digestibility of DM was very similar for hay and silage (0.771 and 0.783 respectively), while the fractional rate of digestion measured by incubation in Dacron bags was significantly (P< 0.05) higher for silage (0.069) than hay (0.057). The rate of passage of mordanted feed out of the rumen was significantly (P< 0.01) faster for silage when determined from concentrations of marker in the rumen (0.034v.0.028 /h). The volume of liquid in the rumen was lower (P< 0.01) for animals consuming silage (27.51) compared with hay (37.11), while the fractional rate of passage of liquid from the rumen was higher (0.141v.0.098 /h,P< 0.05). The volume of liquid in the rumen was also lower (P< 0.05) in steers offered feed eight times daily (29.51), compared with once daily (35.11), but frequency of feeding had no significant effect either on total digestibility or on rate of digestion in the rumen. Thead lib.intake of silage was significantly (P< 0.01) lower than that of hay (4.53v.5.16 kg DM/d) in Expt 2.
Studies of method of conserving grass herbage and frequency of feeding in cattle
Authors: Thiago L. R. L. , Gill M. , Sissons J. W.
Published: May 2005

The influence of the method of conserving grass herbage and the frequency of feeding on eating behaviour, rumen motility and rumen fill was studied in growing steers. Silage and hay were offered to twelve rumen-cannulated Friesian steers (average initial live weight (LW) 128 kg) at a restricted level of intake (20 g dry matter (DM)/kg LW) either once or eight times daily. With once daily feeding, the daily intake of hay was consumed in a single large meal which lasted about 2 h, while silage was eaten in many small meals throughout the day. The proportion of the day spent ruminating was higher (0·39) for steers offered hay once daily than for those offered silage (0·28) or hay eight times per day (0·29). There was little effect of conservation method on frequency of rumen contraction, but contractile intensity (integration of frequency and amplitude) increased during the second half of the 24 h feeding cycle in steers offered hay either once daily or eight times daily, while the same effect was only observed when silage was offered once daily. Total daily contractile activity (the integration of the frequency and duration of myoelectric spike bursts) was significantly (P < 0·05) higher in steers offered hay, compared with silage, once daily. The mean weight of organic matter in the reticulo-rumen of steers offered hay was significantly higher than for silage both with once (1593 v. 1326 g organic matter (OM)/100 kg LW, P < 0·01) and eight (1367 v. 1160 g OM/100 kg LW, P < 0·05) times daily feeding. The proportion of the particulate pool which was present as small (< 1·2 mm) particles was always greater than 0·60.
The effect of the α2-adrenergic agonist, guanfacin, on the energy metabolism of steers fed on low-quality-roughage diets
Authors: Hunter R. A.
Published: May 2005

The effect of the α2-adrenergic agonist, guanfacin, on the energy metabolism, feed intake and live weight (LW) change of steers was studied in three experiments. In the first, the metabolic rate of twelve steers was measured after a 72 h fast. The next day, after a 96 h fast, six steers were injected intramuscularly with 15 mg guanfacin in sterile saline (9 g sodium chloride/l) and six with sterile saline alone, and metabolic rate was measured again. Treatment significantly (P < 0.01) lowered metabolic rate by approximately 20% (53.9 v. 66.8 kJ/kg per d). In the second experiment twelve steers were fed on long-chopped, low-quality roughage (Pangola grass (Digitaria decumbens) hay) ad lib. for 6 weeks. Six steers were continuously infused through a jugular catheter with 15 mg guanfacin/d (about 40 μg/kg LW) in sterile saline. The other six served as controls. There was no significant effect of treatment on feed intake (g dry matter (DM)/kg LW) or the rate of LW loss. Treatment significantly (P < 0.05) increased the retention time of fluid (17.9 v. 22.1 h) in the alimentary tract. In the final experiment twenty-three steers were divided into four treatment groups and fed on long-chopped, low-quality roughage (Pangola hay). Treated animals were continuously infused with guanfacin at the rate of 20, 40 or 80 μg/kg LW per d. Control steers were not infused. At the end of the 6-week feeding period metabolic rate was measured after a 72 h fast. Regardless of dose, guanfacin significantly (P < 0.01) lowered metabolic rate. Feed intake was not significantly affected by treatment but the rate of LW loss was significantly (P < 0.05) less in treated steers.
Effects of diet, level of intake, sodium bicarbonate and monensin on urinary allantoin excretion in sheep
Authors: Dewhurst R. J. , Webster A. J. F.
Published: May 2005

The present experiment was designed to study the effects of factors likely to alter microbial purine yield from the rumen on urinary excretion of allantoin-nitrogen (UAN). Sixteen mature Clun Forest–Welsh crossbred wethers were used in a 2 × 2 × 2 × 2 factorial design to investigate the effects of (1) level of intake, (2) wheat: nutritionally improved straw (NIS) ratio, (3) sodium bicarbonate inclusion and (4) monensin inclusion on diet digestibilities, fractional outflow rates of solids and liquids from the rumen and urinary allantoin excretion. Each treatment occurred in each of two experimental periods. The treatments were designed to influence microbial purine yield via changes in rumen outflow rate and microbial maintenance coefficient. Increasing the proportion of NIS and increasing feeding level decreased digestibility and increased the fractional outflow rate of solids. Increasing the level of intake increased the fractional outflow rate of liquids. Urinary allantoin excretion (/kg live weight0.75per d) was significantly increased by an increased proportion of wheat in the diet and increased level of intake, and significantly reduced by NaHCO3. There was a significant interaction effect such that increasing level of intake did not increase UAN with the high-NIS diet, despite an increased fractional outflow of solids from the rumen, in contrast to the increase observed with the high-wheat diet. Taken together with other observations it is suggested that high sodium concentrations in the diet reduce the efficiency of microbial synthesis, probably by increasing the energy cost of maintaining osmolarity. Monensin had no overall effect on UAN but there were significant interactions between monensin and dietary Na; the inhibitory effect of monensin on UAN was eliminated or reversed in the presence of added NaHCO3. This is consistent with theories that monensin increases the net influx of hydrogen ions into microbial cells and that this influx can be reduced by increased extracellular sodium ions.
The effect of forage and forage–concentrate diets on rumen fermentation and metabolism of nutrients by the mesenteric- and portal-drained viscera in growing steers
Authors: Seal C. J. , Parker D. S. , Avery P. J.
Published: May 2005

Growing Friesian steers chronically catheterized in the anterior mesenteric and portal veins were used to study the influence of feeding with either a forage or forage–concentrate diet on nutrient utilization by mucosal tissue. When animals were consuming the forage–concentrate diet the molar proportion of propionate in rumen fluid was significantly increased, although production rate as measured by isotope dilution was not altered. Net rates of absorption of VFA into portal blood when compared with rumen production rates underlined the extent to which metabolism within mucosal tissue modifies the propionate supply to the liver. Net glucose utilization by splanchnic tissue was shown to be significantly lower on the forage–concentrate diet. There were no effects of diet on whole-body glucose turnover or on the proportion of glucose derived from propionate. Animals fed on the forage–concentrate diet had significantly lower concentrations of circulating essential amino acids, due mainly to a reduction in branched-chain amino acid levels. There was net absorption of all amino acids by animals on both diets except for glutamate, glutamine and taurine in forage-fed animals.
Influence of the amount of starch on the glycaemic index to rice in non-insulin-dependent diabetic subjects
Authors: Rasmussen O. , Gregersen S. , Hermansen K.
Published: May 2005

To test whether the glycaemic index is altered by the amount of carbohydrate, meals containing 25 and 50 g carbohydrate as white rice and white bread were taken by seven non-insulin-dependent diabetic subjects. The glycaemic indices to parboiled white rice corresponding to 25 and 50 g carbohydrate were similar, being 55 (SE 10) and 60 (SE 8) respectively. The incremental areas of blood glucose (above basal) to parboiled white rice were significantly lower than to white bread after both an amount corresponding to 25 g carbohydrate (85 (SE 24) mM × 180 min v. 181 (SE 55) mM × 180 min; P < 0.01) and to 50 g carbohydrate 226 (SE 29) mM × 180 min v. 423 (SE 76) mM × 180 min; P < 0.01). Similar insulin response areas to 25 g carbohydrate given as parboiled white rice and white bread were found, whereas 50 g carbohydrate as white bread caused a significantly higher insulin response area than parboiled white rice (P < 0.05).

In conclusion, the glycaemic index of parboiled white rice is not affected by the amount of carbohydrate ingested, at least under the present study conditions.
Influence of amount of dietary fat and protein on esterase-1 (ES-1) activities of plasma and small intestine in rats
Authors: Lith H. A. Van , Meijer G. W. , van der Wouw M. J. A. , Bieman M. Den , Tintelen G. Van , Zutphen L. F. M. Van , Beynen A. C.
Published: May 2005

The objective of the present study was to characterize nutritionally esterase-1 (ES-1). For this purpose, the effects of replacement of dietary carbohydrates by isoenergetic amounts of either fat or protein on ES-1 activities of plasma and small intestine were studied in male rats. Purified diets differing in the amounts of maize starch plus dextrose, casein and various types of fat were used. Plasma and jejunal ES-1 activities were found to be increased with increasing fat intakes. As to the type of fat, increasing plasma ES-1 activities were induced by coconut fat, olive oil, maize oil and medium-chain triacylglycerols, in this order. Maize oil induced higher jejunal ES-1 activities than coconut fat and olive oil, but had similar effects to medium-chain triacylglycerols. Maize oil was more powerful in increasing plasma ES-1 activity than isoenergetic amounts of casein, but with respect to jejunal ES-1 activity these dietary components were equally effective. It is concluded that the amounts of fat and protein in the diet are important determinants of ES-1 activities in plasma and jejunum.
Muscle protein degradation assessed by Nt-methylhistidine excretion in mature White Leghorn, dwarf broiler and normal broiler males maintained on either low- or high-protein diets
Authors: Hocking P. M. , Saunderson C. Linda
Published: May 2005

Protein degradation rates were assessed by the excretion of Nt-methylhistidine (NtMH) in four strains of mature chickens, two White Leghorns and two broilers (dwarf and normal), fed on diets containing two levels of dietary protein. Over 0.9 of labelled NtMH was recovered within 7 d of injection from three White Leghorn, three dwarf and three normal broiler males. Protein degradation, measured by NtMH output, was related to adult body-weight by the power 0.71 and strain intercepts were significantly different. Strain differences disappeared when the rate of output of NtMH per unit lean was evaluated. The rate of output of NtMH per unit muscle was higher in birds fed on a low-protein diet of 100 g crude protein (nitrogen x 6.25; CP)/kg compared with males fed on 150 g CP/kg. It was concluded that the lower rate of protein degradation in broiler compared with layer strains at young ages is related to increased adult body-weight in agreement with well-established biological principles.
The availability of lysine in diets for pigs: comparative methodology
Authors: Leibholz Jane
Published: May 2005

Four experiments were conducted to compare different methods for estimating the availability of lysine in protein feeds. The same feeds were used in all experiments. In the first experiment the apparent digestibility of lysine to the ileum of growing pigs was found to be 0.92, 0.69, 0.73, 0.85, 0.84 and 0.97 for soya-bean meal, cottonseed meal 1, cottonseed meal 2, meat meal, sunflower meal and skim milk respectively. In the second experiment the utilization of lysine (relative to free lysine) for weight gain, as measured in weaner pigs, was found to be 0.68, 0.73, 0.81, 0.86 and 1.00 for cottonseed meal 1, cottonseed meal 2, meat meal, sunflower meal and skim milk respectively. In Expt 3 diets were formulated to contain soya-bean meal, sunflower meal or cottonseed meal 2 with the same available lysine content from the measurements made in Expts 1 and 2. The feed conversion ratios of weaner pigs given these diets were similar for the three sources of protein when the values were adjusted for the differences in digestible dry matter intake. In the fourth experiment isoenergetic and isonitrogenous diets were formulated with increasing amounts of lysine from synthetic lysine or cottonseed meal 2. The diets were given to weaner pigs and resulted in a curvilinear response to lysine particularly for the cottonseed meal, so that the availability of lysine in cottonseed meal was similar to that of synthetic lysine at low lysine intakes and much lower than synthetic lysine at higher lysine intakes. Possible reasons for the curvilinear responses are discussed.
Zinc absorption in adult men from a chicken sandwich made with white or wholemeal bread, measured by a double-label stable-isotope technique
Authors: Fairweather-Tait Susan J. , Fox Thomas E. , Wharf S. Gabrielle , Eagles John , Kennedy Hugh
Published: May 2005

Eleven fasted adult men consumed a chicken meat sandwich made with white or wholemeal bread, extrinsically labelled with 2 mg67Zn, on two different occasions. Immediately after eating the sandwich they were given an intravenous injection of 1·5 mg70Zn. True Zn absorption (which was approximately 7% higher than apparent absorption) was determined by the faecal balance technique by making an allowance for endogenous excretion from measurements of faecal excretion of70Zn. There was no significant difference in mean true Zn absorption from the white or wholemeal bread sandwich, 33·6 and 25·4% respectively. It was concluded that the substitution of wholemeal for white bread does not reduce Zn absorption from meat-based sandwiches.
Calcium and phosphorus requirements of the very young turkey as determined by response surface analysis
Authors: Sanders Alan M. , Jr Hardy M. Edwards , Rowland III George N.
Published: May 2005

The first experiment was a central composite rotatable design with calculated calcium levels of 6.2, 7.0, 9.0, 11.0, and 11.8 g/kg diet and total phosphorus levels of 5.2, 6.0, 8.0, 10.0, and 10.8 g/kg diet (2.8 g phytin-P/kg by analysis). This design involved three replicates for each rotatable point and fifteen replicates of the central point. The second experiment was a 4 × 4 factorial design with calculated Ca levels of 8.0, 10.0, 12.0, and 14.0 g/kg diet and calculated total P levels of 7.0, 9.0, 11.0, and 13.0 g/kg diet (2.5 g phytin-P/kg by analysis). There were four replicates for each treatment. In both 16 d experiments maize–soya-bean diets were used and each replicate consisted of one pen containing 10-d-old broad-breasted, white tom turkeys. The Ca and total P requirements for optimum growth were estimated to be 12.5 and 10.0 g/kg diet respectively. Bone ash was adequate at these levels of Ca and total P, but maximum bone ash was not achieved until much higher levels of Ca and total P were employed. At the required levels of Ca and total P for growth the incidences of Ca- and P-deficiency rickets were very low. There were no treatment effects on feed efficiency. Increasing dietary Ca decreased the incidence of the Ca-deficiency lesion. There was a quadratic response due to dietary total P on both P-deficiency rickets and plasma dialysable P; intermediate levels of dietary P resulted in low incidence of the P-deficiency lesion and high levels of plasma dialysable P. There was a strong negative correlation between the incidence of P-deficiency rickets and plasma dialysable P. Percentage retention was very low at high levels of dietary P and low levels of Ca which corresponded with slightly higher P-deficiency rickets and low plasma dialysable P. No such obvious relationships existed between Ca retention, incidence of Ca-deficiency rickets, and plasma Ca. The incidence of tibial dyschondroplasia was very low in the present study. There were pronounced dietary treatment effects on phytin-P retention; at 14 d percentage phytin-P retention treatment means ranged from 18 to 46 in Expt 1 and from 0 to 40 in Expt 2 with the highest retention of phytin-P at low levels at both Ca and total P.

Calcium: Phosphorus: Phytin-phosphorus retention: Rickets: Tibial dyschondroplasia: Turkey
Application of selective extraction to the study of iron species present in diet and rat gastrointestinal tract contents
Authors: Simpson Robert J. , Sidhar Sanjiv , Peters Timothy J.
Published: May 2005

Iron speciation in rodent diet and rat gastrointestinal tract lumen during dietary digestion and absorption was investigated with a novel selective extraction technique. Five Fe fractions were identified, namely exchangeable (soluble in 1 M-magnesium chloride), carbonate-bound (soluble in mild acid), oxide-bound (soluble in hydroxylamine–acetic acid), organic-bound (soluble after treatment with peroxide in nitric acid) and residual. Fe from the pelleted diet was mobilized by rat stomach to the exchangeable fraction, then redistributed to the carbonate- and oxide-bound fractions on passage through the proximal small intestine. In vitro incubation of diet with hydrochloric acid failed to mimic the in vivo effect of the stomach. In vitro neutralization of stomach contents with bicarbonate was found to produce a similar effect on Fe speciation to that seen when diet passed the proximal small intestine in vivo. Comparison of59Fe speciation in extrinsically labelled diet with endogenous Fe speciation showed that extrinsic labelling does not uniformly label all endogenous species. The experiments suggest that selective extraction may provide a useful approach to the study of Fe species present in diets, in vitro digestions and gastrointestinal contents.
Effect of vitamin C on sorbitol in the lens of guinea-pigs made diabetic with streptozotocin
Authors: Bates C. J. , Cowen T. D. , Evans P. H.
Published: May 2005

Marginally vitamin C-deficient guinea-pigs treated with the diabetogenic agent streptozotocin were compared with those liberally supplied with vitamin C, for functional indices of vitamin C status, particularly in the eye lens. Weanling male Dunkin–Hartley guinea-pigs were fed on diets with 0.1 g vitamin C/kg (marginally deficient), or 5 g/kg (liberally supplied), and some received intraperitoneal streptozotocin (two doses of 150 mg/kg body-weight). About half the streptozotocin-treated animals had high urinary glucose following an oral glucose dose; these animals also grew more slowly than the others. At 4 months after streptozotocin the animals were killed for measurement of tissue vitamin C, glucose and sorbitol. Streptozotocin moderately increased the concentration of glucose in plasma, lens and aqueous humour. Lens sorbitol levels increased only in the group exposed to streptozotocin plus marginal vitamin C. There was a significant (P < 0.02) positive correlation between urinary glucose and lens sorbitol levels overall. Liberal vitamin C intake may thus counteract the effect of streptozotocin diabetes on lens sorbitol, suggesting a new function of vitamin C, possibly related to cataractogenesis and to the biochemical lesions associated with diabetes.
Tissue α-tocopherol status during late fetal and early neonatal life of the guinea-pig
Authors: Kelly Frank J. , Safavi Morteza , Cheeseman Kevin H.
Published: May 2005

The α-tocopherol content of a number of different fetal, neonatal and maternal guinea-pig tissues was determined and compared with plasma and erythrocyte α-tocopherol values. During late gestation, the fetal liver appears to act as a storage site for α-tocopherol, the majority of which is released immediately following birth. In contrast, lung and brain vitamin E levels are relatively constant over the final period of gestation and during early neonatal life. The ontogeny of α-tocopherol in brain and lung was similar to that for erythrocytes while plasma α-tocopherol content varied considerably and did not accurately reflect tissue α-tocopherol status. Surprisingly, fetal and maternal lung α-tocopherol concentrations were similar at all time-points considered, whereas fetal liver α-tocopherol status was always considerably greater than maternal liver α-tocopherol content. These results, if representative of the human fetus, suggest that preterm infants may not have tissue α-tocopherol concentrations as low as previously assumed and that during the perinatal period erythrocyte α-tocopherol content is a more accurate indicator of tissue α-tocopherol concentration than plasma α-tocopherol content.
Digestion of complex carbohydrates and large bowel fermentation in rats fed on raw and cooked peas (Pisum sativum)
Authors: Goodlad J. S. , Mathers J. C.
Published: May 2005

Rats were fed on four semi-purified diets in which raw or cooked peas (Pisum sativumvar. Sentinel) provided 250 or 500 g/kg diet. Pressure-cooking of peas followed by rapid freezing and freeze-drying increased the proportion of starch resistant to α-amylase (EC3.2.1.1) without previous treatment with dimethyl sulphoxide. There were only minor effects of cooking on the digestibilities of non-starch polysaccharides and their constituent sugars. With the higher dietary pea concentration there were marked increases in the flow of organic matter to, and fermentation in, the large bowel. These increases were associated with significant increases in colonic tissue and contents weights, and in colonic transit time. Both cooking and dietary pea inclusion rate altered the pattern of volatile fatty acids in caecal contents and in portal blood.
Contribution of the digestive tract microflora to amylomaize starch degradation in the rat
Authors: Andrieux Claude , Pacheco Emperatriz Delahaye , Bouchet Brigitte , Gallant Daniel , Szylit Odette
Published: May 2005

To study in vivo the contribution of the bacterial flora to amylomaize starch degradation in the rat, germ-free and conventional rats were fed on a diet containing either a normal maize starch or an amylomaize starch. In germ-free rats maize starch was almost totally digested in the small intestine, whereas 40% of the ingested amylomaize starch reached the caecum and 30% was excreted, despite the very high endogenous amylase activity. Study by transmission electron microscopy of germ-free caecal contents showed an endocorrosion of the starch granule. In conventional rats, as in germ-free rats, digestibility of maize starch reached 98% in the small intestine, whereas that of amylomaize starch was only 60%. In the caecum of these rats amylomaize starch was fermented, and this led to a decrease in caecal pH and to formation of short-chain fatty acids (SCFA), especially propionate. Comparison between conventional rats fed on maize starch or amylomaize starch showed that caecal SCFA concentrations during a circadian cycle varied in the same way whereas total SCFA and lactic acid concentrations were much higher in rats fed on amylomaize starch. Amylase (EC3.2.1.1) activity was similar in the caecal contents of conventional rats whatever the ingested starch. It was lower in conventional than in germ-free rats, but no starch granule remained in the caecum of conventional rats. These results showed that bacterial amylase was more efficient at degrading resistant amylomaize starch than endogenous amylase.
The effects of acute and chronic administration of n-6 and n-3 polyunsaturated fatty acids on ethanol-induced gastric haemorrhage in rats
Authors: Hunter B. , McDonald G. S. A. , Gibney M. J.
Published: May 2005

Female weanling rats in three equal groups (n12) were given orally by intubation 1 ml micellar solution of taurocholic aicd (10 mM) and either arachidonic acid (20:4n−6), linoleic acid (18:2n−6) or eicosapentaenoic acid (20:5n−3) at a concentration of 120 mM. After 1 h the rats were given intragastrically 2 ml absolute ethanol and were killed 1 h later. Rats given oral 20:4n−6 showed a significant reduction (P< 0.05) in the extent (%) of gastric mucosal haemorrhage compared with either the rats given 20:5n−3 or 18:2n−6 (8.3 (SD 7.3), 23.2 (SD 10.4) and 21.4 (SD 10.4)) respectively. In a second experiment, four equal groups (n12) of female Wistar rats were fed for 5 weeks on either a control diet of standard laboratory rat food, or the same diet enriched with either maize oil or fish oil or butterfat at a level of 100 g/kg. Following a 24 h fast the rats received an intragastric dose of 2 ml ethanol and were killed 1 h later. Examination of the extent (%) of gastric lesion showed a significant reduction (P< 0.05) with the feeding of either maize oil or fish oil compared with the controls (12.2 (SD 8.2), 15.3 (SD 13.2) and 29.3 (SD 14.0) respectively). The butterfat diet was not significantly different from the control diet (23.8 (SD 8.1)).
Induction of vascular leakage through release of bradykinin and a novel kinin by cysteine proteinases from Staphylococcus aureus
Authors: Imamura Takahisa , Tanase Sumio , Szmyd Grzegorz , Kozik Andrzej , Travis James , Potempa Jan
Published: May 2005

Staphylococcus aureus is a major pathogen of gram-positive septic shock and frequently is associated with consumption of plasma kininogen. We examined the vascular leakage (VL) activity of two cysteine proteinases that are secreted by S. aureus. Proteolytically active staphopain A (ScpA) induced VL in a bradykinin (BK) B2-receptor–dependent manner in guinea pig skin. This effect was augmented by staphopain B (SspB), which, by itself, had no VL activity. ScpA also produced VL activity from human plasma, apparently by acting directly on kininogens to release BK, which again was augmented significantly by SspB. Intravenous injection of ScpA into a guinea pig caused BK B2-receptor–dependent hypotension. ScpA and SspB together induced the release of leucyl-methionyl-lysyl-BK, a novel kinin with VL and blood pressure–lowering activities that are equivalent to BK. Collectively, these data suggest that production of BK and leucyl-methionyl-lysyl-BK by staphopains is a new mechanism of S. aureus virulence and bacterial shock. Therefore, staphopain-specific inhibitors and kinin-receptor antagonists could be used to treat this disease.
Antigen persistence is required throughout the expansion phase of a CD4+ T cell response
Authors: Obst Reinhard , van Santen Hisse-Martien , Mathis Diane , Benoist Christophe
Published: May 2005

For CD8+ T cells, a relatively short antigen pulse seems sufficient for antigen-presenting cells to drive clonal expansion and differentiation. It is unknown whether the requirement for antigen is similarly ephemeral for CD4+ T cells. To study the dependence of a CD4+ T cell response on antigen persistence in a quantitatively and temporally controlled manner in vivo, we engineered a mouse line expressing a major histocompatibility complex class II–restricted epitope in dendritic cells under the control of a tetracycline-inducible promoter. Experiments tracking the proliferation of CD4+ T cells exposed to their cognate antigen in various amounts for different time periods revealed that the division of such cells was contingent on the presence of antigen throughout their expansion phase, even in the presence of an inflammatory stimulus. This previously unrecognized feature of a CD4+ T cell response contrasts with the proliferative behavior of CD8+ T cells that has been documented, and it implies that the two T cell subsets might require different strategies for efficient vaccination.
Structural Requirements for Differential Sensitivity of KCNQ K+Channels to Modulation by Ca2+/Calmodulin
Authors: Gamper Nikita , Li Yang , Shapiro Mark S.
Published: May 2005

Calmodulin modulation of ion channels has emerged as a prominent theme in biology. The sensitivity of KCNQ1–5 K+channels to modulation by Ca2+/calmodulin (CaM) was studied using patch-clamp, Ca2+imaging, and biochemical and pharmacological approaches. Coexpression of CaM in Chinese hamster ovary (CHO) cells strongly reduced currents of KCNQ2, KCNQ4, and KCNQ5, but not KCNQ1 or KCNQ3. In simultaneous current recording/Ca2+imaging experiments, CaM conferred Ca2+sensitivity to KCNQ4 and KCNQ5, but not to KCNQ1, KCNQ3, or KCNQ1/KCNE1 channels. A chimera constructed from the carboxy terminus of KCNQ4 and the rest KCNQ1 displayed Ca2+sensitivity similar to KCNQ4. Chimeras constructed from different lengths of the KCNQ4 carboxy terminal and the rest KCNQ3 localized a region that confers sensitivity to Ca2+/CaM. Lobe-specific mutations of CaM revealed that its amino-terminal lobe mediates the Ca2+sensitivity of the KCNQ/CaM complex. The site of CaM action within the channel carboxy terminus overlaps with that of the KCNQ opener N-ethylmaleimide (NEM). We found that CaM overexpression reduced NEM augmentation of KCNQ2, KCNQ4, and KCNQ5, and NEM pretreatment reduced Ca2+/CaM-mediated suppression of M current in sympathetic neurons by bradykinin. We propose that two functionally distinct types of carboxy termini underlie the observed differences among this channel family.
Basal Activation of the P2X7 ATP Receptor Elevates Mitochondrial Calcium and Potential, Increases Cellular ATP Levels, and Promotes Serum-independent Growth
Authors: Adinolfi Elena , Callegari Maria Giulia , Ferrari Davide , Bolognesi Chiara , Minelli Mattia , Wieckowski Mariusz R. , Pinton Paolo , Rizzuto Rosario , Di Virgilio Francesco
Published: May 2005

P2X7 is a bifunctional receptor (P2X7R) for extracellular ATP that, depending on the level of activation, forms a cation-selective channel or a large conductance nonselective pore. The P2X7R has a strong proapoptotic activity but can also support growth. Here, we describe the mechanism involved in growth stimulation. Transfection of P2X7R increases resting mitochondrial potential (Δψmt), basal mitochondrial Ca2+ ([Ca2+]mt), intracellular ATP content, and confers ability to grow in the absence of serum. These changes require a full pore-forming function, because they are abolished in cells transfected with a mutated P2X7R that retains channel activity but cannot form the nonselective pore, and depend on an autocrine/paracrine tonic stimulation by secreted ATP. On the other hand, sustained stimulation of P2X7R causes a Δψmt drop, a large increase in [Ca2+]mt, mitochondrial fragmentation, and cell death. These findings reveal a hitherto undescribed mechanism for growth stimulation by a plasma membrane pore.
Cathepsin B Regulates the Intrinsic Angiogenic Threshold of Endothelial Cells
Authors: Im Eunok , Venkatakrishnan Annapurna , Kazlauskas Andrius
Published: May 2005

The lysosomal protease cathepsin B has been implicated in a variety of pathologies including pancreatitis, tumor angiogenesis, and neuronal diseases. We used a tube formation assay to investigate the role of cathepsin B in angiogenesis. When cultured between two layers of collagen I, primary endothelial cells formed tubes in response to exogenously added VEGF. Overexpressing cathepsin B reduced the VEGF-dependent tube response, whereas pharmacologically or molecularly suppressing cathepsin B eliminated the dependence on exogenous VEGF. However, tube formation still required VEGF receptor activity, which suggested that endothelial cells generated VEGF. Indeed, VEGF mRNA and protein was detectable in cells treated with cathepsin B inhibitor, which correlated with a rise in the level of HIF-1α. In addition to boosting the level of proangiogenic factors, blocking cathepsin B activity reduced the amount of the antiangiogenic protein endostatin. Thus endothelial cells have the intrinsic capacity to generate pro- and antiangiogenic agents. These observations complement and expand our appreciation of how endothelial cell–derived proteases regulate angiogenesis.
Impaired Akt Activity Down-Modulation, Caspase-3 Activation, and Apoptosis in Cells Expressing a Caspase-resistant Mutant of RasGAP at Position 157
Authors: Yang Jiang-Yan , Walicki Joël , Michod David , Dubuis Gilles , Widmann Christian
Published: May 2005

RasGAP bears two caspase-3 cleavage sites that are used sequentially as caspase activity increases in cells. When caspase-3 is mildly activated, RasGAP is first cleaved at position 455. This leads to the production of an N-terminal fragment, called fragment N, that activates the Ras-PI3K-Akt pathway and that promotes cell survival. At higher caspase activity, RasGAP is further cleaved at position 157 generating two small N-terminal fragments named N1 and N2. We have now determined the contribution of this second cleavage event in the regulation of apoptosis using cells in which the wild-type RasGAP gene has been replaced by a cDNA encoding a RasGAP mutant that cannot be cleaved at position 157. Our results show that cleavage of fragment N at position 157 leads to a marked reduction in Akt activity. This is accompanied by efficient processing of caspase-3 that favors cell death in response to various apoptotic stimuli. In nontumorigenic cells, fragments N1 and N2 do not modulate apoptosis. Therefore, the role of the second caspase-mediated cleavage of RasGAP is to allow the inactivation of the antiapoptotic function of fragment N so that caspases are no longer hampered in their ability to kill cells.
Induction of Human NF-IL6β by Epidermal Growth Factor Is Mediated through the p38 Signaling Pathway and cAMP Response Element-binding Protein Activation in A431 Cells
Authors: Wang Ju-Ming , Tseng Joseph T. , Chang Wen-Chang
Published: May 2005

The CCAAT/enhancer binding protein δ (C/EBPδ, CRP3, CELF, NF-IL6β) regulates gene expression and plays functional roles in many tissues, such as in acute phase response to inflammatory stimuli, adipocyte differentiation, and mammary epithelial cell growth control. In this study, we examined the expression of human C/EBPδ (NF-IL6β) gene by epidermal growth factor (EGF) stimulation in human epidermoid carcinoma A431 cells. NF-IL6β was an immediate-early gene activated by the EGF-induced signaling pathways in cells. By using 5′-serial deletion reporter analysis, we showed that the region comprising the –347 to +9 base pairs was required for EGF response of the NF-IL6β promoter. This region contains putative consensus binding sequences of Sp1 and cAMP response element-binding protein (CREB). The NF-IL6β promoter activity induced by EGF was abolished by mutating the sequence of cAMP response element or Sp1 sites in the –347/+9 base pairs region. Both in vitro and in vivo DNA binding assay revealed that the CREB binding activity was low in EGF-starved cells, whereas it was induced within 30 min after EGF treatment of A431 cells. However, no change in Sp1 binding activity was found by EGF treatment. Moreover, the phosphatidylinositol 3 (PI3)-kinase inhibitor (wortmannin) and p38MAPKinhibitor (SB203580) inhibited the EGF-induced CREB phosphorylation and the expression of NF-IL6β gene in cells. We also demonstrated that CREB was involved in regulating the NF-IL6β gene transcriptional activity mediated by p38MAPK. Our results suggested that PI3-kinase/p38MAPK/CREB pathway contributed to the EGF activation of NF-IL6β gene expression.
Regulation of Membrane Localization of Sanpodo bylethal giant larvaeandneuralizedin Asymmetrically Dividing Cells ofDrosophilaSensory Organs
Authors: Roegiers Fabrice , Jan Lily Yeh , Jan Yuh Nung
Published: May 2005

In Drosophila, asymmetric division occurs during proliferation of neural precursors of the central and peripheral nervous system (PNS), where a membrane-associated protein, Numb, is asymmetrically localized during cell division and is segregated to one of the two daughter cells (the pIIb cell) after mitosis. numb has been shown genetically to function as an antagonist of Notch signaling and also as a negative regulator of the membrane localization of Sanpodo, a four-pass transmembrane protein required for Notch signaling during asymmetric cell division in the CNS. Previously, we identified lethal giant larvae (lgl) as a gene required for numb-mediated inhibition of Notch in the adult PNS. In this study we show that Sanpodo is expressed in asymmetrically dividing precursor cells of the PNS and that Sanpodo internalization in the pIIb cell is dependent cytoskeletally associated Lgl. Lgl specifically regulates internalization of Sanpodo, likely through endocytosis, but is not required for the endocytosis Delta, which is a required step in the Notch-mediated cell fate decision during asymmetric cell division. Conversely, the E3 ubiquitin ligase neuralized is required for both Delta endocytosis and the internalization of Sanpodo. This study identifies a hitherto unreported role for Lgl as a regulator of Sanpodo during asymmetric cell division in the adult PNS.
Learning about Learning: A Response to Wand
Authors: Schultz Kenneth A. , Lewis Jeffrey B.
Published: May 2005

We welcome the opportunity to respond to Wand's careful and detailed analysis of our paper (Lewis and Schultz 2003). With the discipline's increasing inclination to move toward fully structural strategic choice models (e.g., Signorino 1999; Morton 1999), the issues that Wand raises are important to consider, as they bear on crucial questions of model construction and interpretation. Moreover, his work has allowed us to consider more carefully the properties of an estimator that we are in the process of applying to actual data.
Pathology during acute infections: contributions of intracellular pathogens and the CTL response
Authors: Ganusov Vitaly V , Antia Rustom
Published: May 2005

Previous work has shown how, in the case of cytotoxic T-lymphocyte (CTL) responses to persistent viral infections, pathology may arise as a consequence of cell destruction directly by the virus or indirectly due to the CTL response, leading to maximum pathology at intermediate efficacy of the immune response. We expand these studies to consider pathology arising during acute infections with intracellular pathogens controlled by the CTL response. We show that, in contrast to persistent infections, pathology during acute infections is minimized with increasing efficacy of the immune response. The implications of these results for vaccination are discussed.