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BACKGROUND: Adult skeletal muscle myogenesis depends on the activation of satellite cells that have the potential to differentiate into new fibers. Gamma-oryzanol (GO), a commercially available nutriactive phytochemical, has gained global interest on account of its muscle-building and regenerating effects. Here, we investigated GO for its potential influence on myogenesis, using equine satellite cell culture model, since the horse is a unique animal, bred and exercised for competitive sport. To our knowledge, this is the first report where the global gene expression in cultured equine satellite cells has been described. METHODS: Equine satellite cells were isolated from semitendinosus muscle and cultured until the second day of differentiation. Differentiating cells were incubated with GO for the next 24 h. Subsequently, total RNA from GO-treated and control cells was isolated, amplified, labeled, and hybridized to two-color Horse Gene Expression Microarray slides. Quantitative PCR was used for the validation of microarray data. RESULTS: Our results revealed 58 genes with changed expression in GO-treated vs. control cells. Analysis of expression changes suggests that various processes are reinforced by GO in differentiating equine satellite cells, including inhibition of myoblast differentiation, increased proliferation and differentiation, stress response, and increased myogenic lineage commitment. CONCLUSIONS: The present study may confirm putative muscle-enhancing abilities of GO; however, the collective role of GO in skeletal myogenesis remains equivocal. The diversity of these changes is likely due to heterogenous growth rate of cells in primary culture. Genes identified in our study, modulated by the presence of GO, may become potential targets of future research investigating impact of this supplement in skeletal muscle on proteomic and biochemical level.

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Gamma-oryzanol (GO) is an abundant dietary antioxidant that is considered to have beneficial effects in cardiovascular disease, cancer and diabetes. Other potential properties of GO include inhibition of gastric acid secretion and decreased post-exercise muscle fatigue. GO is a unique mixture of triterpene alcohol and sterol ferulates present in rice bran oil, a byproduct of rice processing. GO has been studied by many researchers over the last three decades. In particular, the utility of GO supplementation has been documented in numerous animal models. A large variety of species was examined, and various experimental methodologies and targets were applied. The aim of this study was to summarize the body of research on GO supplementation in animals and to examine possible mechanisms of GO action. Furthermore, while the safety of GO supplementation in animals has been well documented, studies demonstrating pharmacokinetics, pharmacodynamics and efficiency are less clear. The observed differences in these findings are also discussed.

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The leucine metabolite ß-hydroxy-ß-methylbutyrate (HMB) has been studied by many researchers over the last two decades. In particular, the utility of HMB supplementation in animals has been shown in numerous studies, which have demonstrated enhanced body weight gain and carcass yield in slaughter animals; positive immunostimulatory effect; decreased mortality; attenuation of sarcopenia in elderly animals; and potential use in pathological conditions such as glucocorticoid-induced muscle loss. The aim of this study was to summarize the body of research on HMB supplementation in animals and to examine possible mechanisms of HMB action. Furthermore, while the safety of HMB supplementation in animals is well documented, studies demonstrating efficacy are less clear. The possible reasons for differences in these findings will also be examined.

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The purpose of this study was to compare the training methods used in two stables and their effects on selected blood parameters and race results. A total number of 36 thoroughbred race horses was examined in two groups, trained by two trainers. Twenty-four horses (group A) were trained at Sluzewiec and the remaining twelve horses (group B) were kept and trained in a private stable. The experiment lasted for five months. The activities of CPK (creatine phosphokinase) and AST (aspartate aminotransferase) and the concentration of LA (lactic acid) were determined. The speed was controlled and recorded by a Garmin GPS system. The analysis of the General Handicap rating demonstrated that the training methods used in stable A were more effective and resulted in better classification of these horses. Training methods in both stables were evaluated and compared on the basis of maximal speeds during training sessions and related post exercise LA concentrations. The main differences between training methods used in both stables concerned the workload and the time of work with the rider. Analysis of the values measured in individual horses from stable B have shown that AST and CK activities were high not only in all young, 2-year-old horses but also in three older ones. This seems to confirm the lack of balance and proper movement coordination in these horses, resulting in high activities of muscle enzymes.

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In this study we wanted to determine whether changes in antioxidant profile could follow the catabolic effects of glucocorticoids. We also wanted to compare resistance to glucocorticoid overload in young and old rats. To address these questions, whole body catabolism was induced by the administration of dexamethasone (Dex) at either 2 mg/kg bodyweight/day to young (6 weeks old) or 0.5 mg/kg body-weight/day to old (94 weeks old) rats. Bodyweight loss of pair-fed rats not given Dex was only 2% in the young rats and 8% in the old rats, whereas in Dex-treated rats the decrease in bodyweight was 22% in the young rats and 13% in the old rats after 5 days of treatment. Spleen weight decreased by 65% in the young rats and by 52% in the old rats. Additionally, in the young rats there was a 46% reduction in glutathione (GSH) in erythrocytes as well as a 36% reduction in GSH/tissue wet weight in the soleus muscle. The corresponding figures for the old rats were 35 and 26%, respectively. Taken together, these results suggest that Dex directly and/or indirectly impaired the antioxidant reactions. This was further confirmed by a significant (50%) decline in Cu-Zn superoxide dismutase (SOD-1) activity in erythrocytes isolated from the young rats treated with Dex but not the old rats as they showed a significant elevation in SOD-1 activity (by 101%). Thiobarbituric acid reactant substances were significantly higher in both young and old rats. Activity of blood plasma creatine kinase increased by 73% in the young rats and by 307% in the old rats treated with Dex. Although both the young and the old rats could recover from oxidative stress, the old rats in contrast to the young rats remained catabolic until the end of the experiment. In conclusion, we suggest that old rats are more vulnerable to the catabolic action of Dex, whereas young rats are more susceptible to the oxidative stress induced by Dex.

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We investigated whether creatine (CR) and beta-hydroxy-beta-methylbutyrate (HMB) act by similar or different mechanisms to increase lean body mass (LBM) and strength in humans undergoing progressive resistance-exercise training. In this double-blind, 3-wk study, subjects (n = 40) were randomized to placebo (PL; n = 10), CR (20.0 g of CR/d for 7 d followed by 10.0 g of CR/d for 14 d; n = 11), HMB (3.0 g of HMB/d; n = 9), or CR-and-HMB (CR/HMB; n = 10) treatment groups. Over 3 wk, all subjects gained LBM, which was assessed by bioelectrical impedance analysis. The CR, HMB and CR/HMB groups gained 0.92, 0.39, and 1.54 kg of LBM, respectively, over the placebo group, with a significant effect with CR supplementation (main effect P = 0.05) and a trend with HMB supplementation (main effect P = 0.08). These effects were additive because there was no interaction between CR and HMB (CR x HMB main effect P = 0.73). Across all exercises, HMB, CR, and CR/HMB supplementation caused accumulative strength increases of 37.5, 39.1, and 51.9 kg, respectively, above the placebo group. The exercise-induced rise in serum creatine phosphokinase was markedly suppressed with HMB supplementation (main effect P = 0.01). However, CR supplementation antagonized the HMB effects on serum creatine phosphokinase (CR x HMB interactive effect P = 0.04). Urine urea nitrogen and plasma urea were not affected by CR supplementation, but both decreased with HMB supplementation (HMB effect P < 0.05), suggesting a nitrogen-sparing effect. In summary, CR and HMB can increase LBM and strength, and the effects are additive. Although not definitive, these results suggest that CR and HMB act by different mechanisms.

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beta-Hydroxy-beta-methyl butyrate(HMB) has been shown to counteract many of the negative effects of intensive animal production methods and results in increased growth and protection against diseases. In the present study, the effect of HMB on the immunocompetence cell activity in rainbow trout (Oncorhynchus mykiss) and carp (Cyprinus carpio) was examined. Pronephric phagocytes and lymphocytes were isolated from the fish and grown in culture medium (RPMI-1640) containing either 0, 0.1, 1, 5, 10, 25, 50 or 100 microg HMB/ml of medium. The effects of HMB on the respiratory burst activity (RBA) stimulated by phorbol myristate acetate (PMA), the potential killing activity (PKA) and lymphocyte proliferation stimulated by either concanavalin A (Con-A) or lipopolysaccharide (LPS) were examined. The addition of HMB to the culture medium increased the RBA by up to 84% (p<0.01) over that of cells grown without HMB. Similarly, the PKA of the phagocytes was also increased with HMB addition to the medium by up to 140% (p<0.01) over that of cells grown without HMB. Lymphocyte proliferation stimulated by both ConA and LPS was also increased approximately two-fold (p<0.01) when HMB was added to the culture medium at concentrations between 10 and 100 microg HMB/ml in both rainbow trout and carp. The greatest effects of HMB on RBA and PKA activities were observed at a concentration >50 microg HMB/ml while lymphocyte proliferation was maximally stimulated at 25 microg HMB/ml. In conclusion, the current study shows that HMB could potentially improve immunocompetence cell activity in fish through increased cell proliferation and functionality.

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The action of glucocorticoids in high doses is catabolic, but not much is known about the accompanying effects on antioxidative capacity of the entire body. Animals were treated (or not) with dexamethasone (Dex) 2 mg/kg b.w. d-1 during 5 consecutive days followed by recovery, during which an additional group received 3-hydroxy-3-methylbutyrate (40 mg/kg b.w.). Animals were killed after treatment with Dex, and after 5 days of the recovery period. Dexamethasone treatment decreased appetite almost twofold (from 20 g/day to 10 g/day, P < 0.001). Feed restriction, however, seemed to have only minor impact on the effects observed since body weight loss of pair-fed rats after the 5th day of treatment was only 2% and Dex-treated rats decrease in body weight was 22% (P < 0.05). In turn, wet weight of the soleus muscle (expressed per body weight) did not significantly decrease after Dex treatment, suggesting relative resistance of oxidative type muscles to the catabolic action of dexamethasone. Spleen wet weight expressed per body weight dropped by 65% (P<0.001). Additionally, there was a 46% reduction (P<0.001) of blood glutathione (GSH/Hb), and 36% (P < 0.001) of muscle glutathione (GSH/tissue wet weight). This suggests that dexamethasone directly and/or indirectly impaired antioxidant reactions. This was further confirmed by a significant (49%) decline of SOD-1 activity in erythrocytes isolated from the group treated with dexamethasone. Another index of lipid peroxidation (TBARS) was also significantly increased. Activity of blood plasma CK increased by 73% (P<0.001) in Dex-treated rats, indicating moderate injury of muscle tissue. In conclusion, young growing rats were sensitive to the dosage of dexamethasone, but in contrast to lymphoid tissue, could easily compensate the outcomes of impaired antioxidative defence within 5 days of recovery.

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Previous research has shown that the value of large future rewards is discounted less steeply than is the value of small future rewards. These experiments extended this line of research to probabilistic rewards. Two experiments replicated the standard findings for delayed rewards but demonstrated that amount has an opposite effect on the discounting of probabilistic rewards. That is, large probabilistic amounts were discounted at the same or higher rates than small amounts. Although amount had opposite effects on the discounting of delayed and probabilistic rewards, nevertheless, the same form of mathematical function accurately described discounting of both types of reward. The findings suggest that fundamentally similar, but not identical, processes are involved in decision making regarding delayed and probabilistic rewards. The implications of these findings for impulsivity and self-control are discussed.

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The present effort addressed both the issue of the generality of choice models and the issue of possible qualitative developmental change in temporal discounting by examining behavior at the individual level across the life span. Data from individual children, young adults, and older adults who participated in two previous studies were analyzed [Green, L., Fry, A.F., Myerson, J., 1994. Discounting of delayed rewards: a life-span comparison. Psychol. Sci. 5, 33-36; Green, L., Myerson, J., Lichtman, D., Rosen, S., Fry, A., 1996. Temporal discounting in choice between delayed rewards: the role of age and income. Psychol. Aging 11, 79-84]. At all ages, a hyperbola-like function originally proposed by Green et al. (1994) based on group data, provided the best description of individual discounting functions. Two developmental trends were observed. The rate at which individuals discounted the value of delayed rewards decreased with age, and there was a systematic change in the shape of the discounting function. Each of these trends was reflected in a separate parameter of the model. The fact that the same mathematical model described the behavior of individuals of different ages suggests that age and individual differences in the discounting of delayed rewards are primarily quantitative in nature and reflect variations on fundamentally similar choice processes.

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The effect of a high dose of 3-hydroxy-3-methylbutyrate (HMB, a leucine catabolite) on protein metabolism was investigated in growing male lambs fed on hay and concentrate. Concentrate was supplemented with either Ca(HMB)2 (4 g/kg) or Ca(CO3)2 in experimental (HMB) and control groups respectively. Both groups consisted of six 2-month old lambs. Three complementary methods to study protein metabolism were carried out consecutively 2.5 months after beginning the dietary treatment: whole body phenylalanine fluxes, postprandial plasma free amino acid time course and fractional rates of protein synthesis in skeletal muscles. Feeding a high dose of HMB led to a significant increase in some plasma free amino acids compared with controls. Total, oxidative and non-oxidative phenylalanine fluxes were not modified by dietary HMB supplementation. Similarly, an acute infusion of HMB, in the control group, did not change these fluxes. In skeletal muscles, fractional rates of protein synthesis were not affected by long-term dietary supplementation with HMB. Taken together our results showed that administration of a high dose of HMB to lambs was able to modify plasma free amino acid pattern without any effect on whole-body protein turnover and skeletal muscle protein synthesis.

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Leucine metabolism was measured isotopically in 12 immature female pigs to assess the effect of acute hyperglucagonemia on leucine kinetics in both the fed and fasting states. After an overnight fast, immature pigs were infused with alpha-[3H]ketoisocaproate and [14C]leucine. After a 2-h equilibration period, an infusion of either saline or 7 pg.kg-1.min-1 of glucagon was begun, which increased plasma glucagon from approximately 140 to approximately 640 pg/ml and doubled the insulin concentrations. Two hours later, pigs were fed small meals to which [5,5,5-2H3]leucine was added to trace absorption. By subtracting absorption from total leucine flux, an estimate of endogenous proteolysis during the meal was made. In the fasting state, glucagon increased proteolysis, relative to controls, by approximately 20% (P less than 0.05) and increased oxidation by approximately 50% (P less than 0.05). No significant glucagon-related changes in any other flux parameters occurred in the fasting state. Ingestion of the meals caused oxidation to increase 41% in control animals, whereas in glucagon-infused animals, oxidation increased 84% (P less than 0.05 control vs. glucagon response to meal). Additionally, animals infused with glucagon suppressed endogenous proteolysis 43% after the meal compared with a 55% decrease in control animals (P less than 0.05 basal period vs. fed period). These data indicate that glucagon stimulates whole-body proteolysis in both the fasting and fed states.

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Leucine metabolism was measured isotopically in immature female pigs to assess the effect of acute infusions of nicotinic acid (NA) on leucine kinetics in both the fed and fasting states. After an overnight fast, immature pigs were infused with 3H-alpha-ketoisocaproate (KIC) and 14C-leucine. After a 2-hour equilibration period, an infusion of either saline or 0.4 mg/kg.min of NA was begun. NA caused a decrease in plasma glucose and an increase in plasma glucagon. During the fasting period, NA increased KIC oxidation 2-fold over controls. After feeding, plasma free fatty acids (FFA) in both groups were equivalent, but KIC oxidation was still approximately 80% higher in NA-infused animals. In addition, NA stimulated proteolysis and inhibited protein synthesis during the meal. Because plasma FFA concentrations were equal during the fed period, it is unlikely that changes in FFA concentrations are responsible for the changes in leucine metabolism observal during NA infusion.

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Ammonium chloride (30 mumol/min/kg bw), lactate (50 mumol/min/kg bw) or ammonium chloride plus lactate were infused for two hours into the mesenteric vein of sheep. Blood samples were taken before, during, and two hours after infusion from portal, hepatic and jugular veins for estimation of ammonia, urea, lactate and glucose. Average portal and hepatic blood flow was 59 +/- 35 and 89 +/- 48 ml/min/kg bw respectively without any regular changes when ammonium chloride or lactate alone were administered. The treatment with ammonium chloride increased the hepatic ammonia fixation from 9.1 +/- 2.1 to 25.2 +/- 5.7 mumol/min/kg bw and urea formation from 17.6 +/- 14.2 to 56.4 +/- 43.2 mumol/min/kg bw. The infusion of ammonium chloride alone provoked a peripheral hyperammonaemia and it increased the endogenous sources of ammonia for urea production. Both lactate and ammonia caused an increase of hepatic glucose release. It was suggested that lactate stimulated mainly gluconeogenesis, and ammonium-glucogenolysis. The effect of ammonia in the last reaction as well as an increased net urea formation in the liver, was probably mediated by the hypoinsulinaemia and/or an increase of adrenaline secretion.

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1. Mixed-breed wethers (40-50 kg), 9 months old, were maintained on high-energy (HED) and low-energy (LED) diets for 2 weeks. 2. After a 15 h fast, a primed-dose constant infusion of L-[U-14C]leucine and alpha-[4,5-3H]ketoisocaproate (KIC) was given. 3. After 2 h, plasma samples were taken and plasma-specific radioactivities of 14C- and 3H-labelled leucine and KIC were measured and analysed by using an open two-pool model. 4. Less than 20% of the total leucine-C entering the circulation was converted to the KIC pool, and 42% of the KIC was converted back to the leucine pool; transamination of the leucine to KIC and reamination of KIC to leucine was much less than in other species. 5. Additional dietary energy resulted in a decrease in tissue protein synthesis, leucine oxidation and interconversion of leucine and KIC. Total leucine-C entry was also lower in sheep given HED, which was most likely due to a suppression of endogenous proteolysis. 6. Plasma glucagon concentration was significantly higher (P less than 0.05) in sheep given LED compared with those given HED. The concentration of glucagon was closely correlated in all treatments with the leucine-C entry (proteolysis + absorbed leucine) and also with KIC-C exit (oxidation).

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