Effects of Whey Protein Combined with Amylopectin/Chromium on the Muscle Protein Synthesis and mTOR Phosphorylation in Exercised Rats.

This study aimed to examine the impact of varying doses of whey protein (WP) and amylopectin/chromium complex (ACr) supplementation on muscle protein synthesis (MPS), amino acid and insulin levels, and the rapamycin (mTOR) signaling pathways in exercised rats. A total of 72 rats were randomly divided into nine groups: (1) Exercise (Ex), (2) Ex + WPI to (5) Ex + WPIV with various oral doses of whey protein (0.465, 1.55, 2.33, and 3.1 g/kg) and (6) Ex + WPI + ACr to (9) Ex + WPIV + ACr with various doses of whey protein combined with 0.155 g/kg ACr. On the day of single-dose administration, the products were given by oral gavage after exercise. To measure the protein fractional synthesis rate (FSR), a bolus dose of deuterium-labeled phenylalanine was given, and its effects were evaluated 1 h after supplementation. Rats that received 3.1 g/kg of whey protein (WP) combined with ACr exhibited the most significant increase in muscle protein synthesis (MPS) compared to the Ex group (115.7%, p < 0.0001). In comparison to rats that received the same dose of WP alone, those given the combination of WP and ACr at the same dosage showed a 14.3% increase in MPS (p < 0.0001). Furthermore, the WP (3.1 g/kg) + ACr group exhibited the highest elevation in serum insulin levels when compared to the Ex group (111.9%, p < 0.0001). Among the different groups, the WP (2.33 g/kg) + ACr group demonstrated the greatest increase in mTOR levels (224.2%, p < 0.0001). Additionally, the combination of WP (2.33 g/kg) and ACr resulted in a 169.8% increase in 4E-BP1 levels (p < 0.0001), while S6K1 levels rose by 141.2% in the WP (2.33 g/kg) + ACr group (p < 0.0001). Overall, supplementation with various doses of WP combined with ACr increased MPS and enhanced the mTOR signaling pathway compared to WP alone and the Ex group.

Evaluation of pea/rice and amylopectin/chromium as an alternative protein source to improve muscle protein synthesis in rats.

BACKGROUND: A preclinical study reported that the combination of an amylopectin/chromium complex (ACr) of branched-chain amino acids (BCAA) significantly enhanced muscle protein synthesis (MPS). This study was conducted to determine the effects of the addition of ACr complex to a pea/rice (PR) protein on MPS, insulin, muslin levels, and the mTOR pathway in exercised rats. METHODS: Twenty-four rats were divided into three groups: (i) exercise (Ex); (ii) Ex + PR 1:1 blend (0.465 g/kg BW); (iii) Ex + PR + ACr (0.155 g/kg BW). On the day of single-dose administration, after the animals were exercised at 26/m/min for 2 h, the supplement was given by oral gavage. The rats were injected with a bolus dose (250 mg/kg BW, 25 g/L) of deuterium-labeled phenylalanine to determine the protein fractional synthesis rate (FSR) one h after consuming the study product. RESULTS: The combination of PR and ACr enhanced MPS by 42.55% compared to the Ex group, while Ex + PR alone increased MPS by 30.2% over the Ex group (p < 0.0001) in exercised rats. Ex + PR plus ACr significantly enhanced phosphorylation of mTOR and S6K1 (p < 0.0001), and 4E-BP1 (p < 0.001) compared to the Ex (p < 0.0001). PR to ACr also significantly increased insulin and musclin levels (p < 0.0001) in exercised rats. Additionally, compared to Ex + PR alone, Ex + PR + ACr enhanced mTOR (p < 0.0001) and S6K1 (p < 0.0001) levels. CONCLUSION: These data suggested that PR + ACr may provide an alternative to animal proteins for remodeling and repairing muscle by stimulating MPS and mTOR signaling pathways in post-exercised rats. More preclinical and clinical human studies on combining pea/rice and amylopectin/chromium complex are required.

Dietary amylose and amylopectin ratio changes starch digestion and intestinal microbiota diversity in goslings.

1. Research has confirmed that amylopectin (AP) is more easily digested than amylose (AM) because AP polymers have more intramolecular hydrogen bonds and less surface area. Studying the relationship between the amylose:amylopectin (AM:AP) ratio and intestine digestion in goslings can provide useful information for effective utilisation of starch.2. A total of 288 healthy male Jiangnan White Goslings, aged three days old, were randomly allotted to four groups, which included six pen replicates per treatment with 12 goslings per replicate. Four diets were formulated with maize, long-grained rice and glutinous rice as starch sources, with AM:AP ratios of 0.12, 0.23, 0.34, and 0.45. In vitro starch digestion of the four diets was measured, as well as the effect of AM:AP ratio on growth performance, serum amino-acid concentration and intestinal microbiota diversity of goslings.3. In terms of in vitro starch digestion, the increase in dietary AM:AP ratio resulted in a decrease followed by an increase in both rapidly and slowly digestible starch. The glucose release rate at an AM:AP ratio of 0.34 showed a steady upward trend.4. The in vivo study showed that increasing the AM:AP ratio resulted in a quadratic increase in body weight (BW) and average daily feed intake (ADFI; P < 0.05). Goslings fed diets with an AM:AP ratio of 0.34 had lower (P < 0.05) histidine and valine serum concentrations compared with the other three starch sources. Higher AM was beneficial to jejunal microbial and diversity. The species colonisation level of the jejunum microbiota samples at an AM:AP ratio of 0.34 was higher than that in the other groups.5. The results indicated that diets with an AM:AP ratio of 0.34 improved the growth performance and intestinal microbiota diversity of goslings. This may have been due to the higher level of resistant starch in amylose, which resulted in a slow release of intestinal glucose that acted as a substrate for the microbial species, thus providing conditions that were more conducive to growth.

Dietary amylose:amylopectin ratio influences the expression of amino acid transporters and enzyme activities for amino acid metabolism in the gastrointestinal tract of goats.

This study was designed to investigate the effects of dietary starch structure on muscle protein synthesis and gastrointestinal amino acid (AA) transport and metabolism of goats. Twenty-seven Xiangdong black female goats (average body weight = 9·00 ± 1·12 kg) were randomly assigned to three treatments, i.e., fed a T1 (normal maize 100 %, high amylose maize 0 %), T2 (normal maize 50 %, high amylose maize 50 %) and T3 (normal maize 0 %, high amylose maize 100 %) diet for 35 d. All AA in the ileal mucosa were decreased linearly as amylose:amylopectin increased in diets (P < 0·05). The plasma valine (linear, P = 0·03), leucine (linear, P = 0·04) and total AA content (linear, P = 0·03) increased linearly with the increase in the ratio of amylose in the diet. The relative mRNA levels of solute carrier family 38 member 1 (linear, P = 0·01), solute carrier family 3 member 2 (linear, P = 0·02) and solute carrier family 38 member 9 (linear, P = 0·02) in the ileum increased linearly with the increase in the ratio of amylose in the diet. With the increase in the ratio of amylose:amylopectin in the diet, the mRNA levels of acetyl-CoA dehydrogenase B (linear, P = 0·04), branched-chain amino acid transferase 1 (linear, P = 0·02) and branched-chain α-keto acid dehydrogenase complex B (linear, P = 0·01) in the ileum decreased linearly. Our results revealed that the protein abundances of phosphorylated mammalian target of rapamycin (p-mTOR) (P < 0·001), phosphorylated 4E-binding protein 1 (P < 0·001) and phosphorylated ribosomal protein S6 kinases 1 (P < 0·001) of T2 and T3 were significantly higher than that of T1. In general, a diet with a high amylose ratio could reduce the consumption of AA in the intestine, allowing more AA to enter the blood to maintain higher muscle protein synthesis through the mTOR pathway.

Starch in aquafeeds: the benefits of a high amylose to amylopectin ratio and resistant starch content in diets for the carnivorous fish, largemouth bass (Micropterus salmoides).

Aquafeeds for carnivorous species face a nutritional-technological conundrum: containing sufficient starch to meet specific manufacturing requirements for binding, extrusion and expansion, but ideally containing as little starch as possible owing to their limited ability to utilise carbohydrates. The present study evaluated the effects of dietary starch with different amylose to amylopectin ratios and resistant starch contents on growth performance, hepatic glycogen accumulation and glucose metabolism of an important cultured carnivorous finfish, largemouth bass (Micropterus salmoides). A common starch source (α-cassava starch (CS)) was tested as is or after being enzymatically de-branched at three different inclusion levels in diets for largemouth bass. Results showed that the increased dietary starch levels compromised performance and high dietary α-CS content led to obvious liver damage. However, the growth performances of fish fed the diets with de-branched starch (DS) were improved, and no manifest liver damages were observed even at the higher inclusion level. The increasing dietary starch contents significantly increased hepatic glycogen accumulation, but not when DS was used. High dietary starch content, without regard to starch sources, had no effect on the expression of glucose metabolism-related genes, except for down-regulation of insulin receptor expression. However, the use of dietary DS promoted the expression of genes involved in the insulin pathway and glycolysis. In conclusion, this study showed that the use of starch sources with a high amylose to amylopectin ratio and resistant starch in the feed for cultured carnivorous finfish could alleviate the hepatic glycogen deposition through regulating the insulin pathway and glycolysis.

The addition of an amylopectin/chromium complex to branched-chain amino acids enhances muscle protein synthesis in rat skeletal muscle.

BACKGROUND: A previous clinical study reported that the addition of an amylopectin/chromium complex (ACr; Velositol®) to 6 g of whey protein (WP) significantly enhanced muscle protein synthesis (MPS). Branched-chain amino acids (BCAAs) are also well-known to enhance MPS. The aim of this study was to determine if the addition of ACr to BCAAs can enhance MPS and activate expression of the mammalian target of the rapamycin (mTOR) pathway compared to BCAAs and exercise alone in exercise-trained rats. METHODS: Twenty-four male Wistar rats were randomly divided into three groups (n = 8 per group): (I) Exercise control, (II) Exercise plus BCAAs (0.465 g/kg BW, a 6 g human equivalent dose (HED)), and (III) Exercise plus BCAAs (0.465 g/kg BW) and ACr (0.155 g/kg BW, a 2 g HED). All animals were trained with treadmill exercise for 10 days. On the day of the single-dose experiment, rats were exercised at 26 m/min for 2 h and then fed, via oral gavage, study product. One hour after the consumption of study product, rats were injected with a bolus dose (250 mg/kg BW, 25 g/L) of phenylalanine labeled with deuterium to measure the fractional rate of protein synthesis (FSR). Ten minutes later, muscle tissue samples were taken to determine MPS measured by FSR and the phosphorylation of proteins involved in the mTOR pathway including mTOR, S6K1, and 4E-BP1. RESULTS: ACr combined with BCAAs increased MPS by 71% compared to the exercise control group, while BCAAs alone increased MPS by 57% over control (p < 0.05). ACr plus BCAAs significantly enhanced phosphorylation of mTOR, S6K1 and 4E-BP1 compared to exercise control rats (p < 0.05). The addition of ACr to BCAAs enhanced insulin levels, mTOR and S6K1 phosphorylation compared to BCAAs alone (p < 0.05). Serum insulin concentration was positively correlated with the levels of mTOR, (r = 0.923), S6K1 (r = 0.814) and 4E-BP1 (r = 0.953). CONCLUSIONS: In conclusion, the results of this study provide evidence that the addition of ACr to BCAAs significantly enhances exercise-induced MPS, and the phosphorylation of mTOR signaling proteins, compared to BCAAs and exercise alone.

Effects of dietary amylose/amylopectin ratio and amylase on growth performance, energy and starch digestibility, and digestive enzymes in broilers.

This study was conducted to investigate the effects of dietary amylose/amylopectin (AM/AP) ratio and amylase on growth performance, apparent digestibility of energy and starch, serum biochemical index, and digestive enzymes. The experiment used a 4 × 3 factor design, and 960 one-day-old Arbor Acres (AA) broilers were randomly divided into 12 groups fed diets containing different AM/AP ratio of 0.11, 0.23, 0.35 and 0.47 and combined with 0, 3,000 and 6,000 U/kg amylase. Results showed that 0.23-0.35 AM/AP ratio increased growth performance, while dietary addition of 6,000 U/kg amylase significantly reduced average daily weight gain in broilers. The energy digestibility was significantly reduced along with the increase of dietary AM/AP ratio and in the 6,000 U/Kg amylase-supplemented groups. The digestibility of starch also decreased significantly with the increase of dietary AM/AP ratio, but high dose (6,000 U/Kg) of amylase increased. High AM/AP diet reduced serum insulin concentration, which was increased in amylase-supplemented groups. Furthermore, exogenous amylase increased amylase activity in the jejunal chyme. In conclusion, dietary 0.23-0.35 AM/AP ratio was suggested to maintain a higher growth performance in broilers and high AM/AP ratio diets reduced energy and starch digestibility and serum insulin concentration, which was reversed by dietary amylase.

Structural and functional characteristics of clustered amylopectin produced by glycogen branching enzymes having different branching properties.

Three bacterial glycogen branching enzymes (GBEs) having different branching characteristics were used to produce clustered amylopectin (CAP), and structure and functional properties of CAPs were intensively analyzed. Branch distributions of three CAPs varied from very short (DPn = 6.65) to medium (DPn = 14.1). Branch distribution showed profound correlation with hydrodynamic diameter, water solubility, digestibility, and effects on mice gut-microbiota. All the CAPs showed nearly no viscosity and retrogradation. The very short-branch CAP exhibited more than 100-fold water-solubility, 3.5-fold lower α-amylase catalytic efficiency, and 27% lower digestibility in small intestine-mimicking condition than amylopectin. Intriguingly, medium branch CAP had 1.8-fold larger hydrodynamic diameter than the very short one. Mice gut-microbiota composition statistically varied after 12-day feeding of the CAPs, but only the medium chain CAP brought clear positive changes on the gut-microbiota. Consequently, slowly digestible starch was successfully synthesized by the single GBE, but the CAP structure affects in vivo functions in complicated manner.

Combination of Soy Protein, Amylopectin, and Chromium Stimulates Muscle Protein Synthesis by Regulation of Ubiquitin-Proteasome Proteolysis Pathway after Exercise.

The present study was undertaken to investigate the effect of the combination of soy protein, amylopectin, and chromium (SAC) on muscle protein synthesis and signal transduction pathways involved in protein synthesis (mTOR pathways, IGF-1, and AktSer473) and proteolysis (FOXO1Ser256; MURF1, MAFbx) after exercise. Thirty-five Wistar rats were randomly divided into five groups: (1) control (C); (2) exercise (E); (3) exercise + soy protein (3.1 g/kg/day) (E + S); (4) exercise + soy protein + chromium (E + S + Cr); (5) exercise + soy protein + amylopectin + chromium (E + S + A + Cr). Post-exercise ingestion of SAC significantly increased the fractional rate of protein synthesis (FSR), insulin, glycogen, and amino acid levels with the highest effect observed in E + S + A + Cr group (P Ë‚ 0.05). However, SAC supplementation decreased the lactic acid concentration (P Ë‚ 0.05). A reduction in forkhead box protein O1 (FOXO1) and forkhead box protein O3 (FOXO3) (regulators of ubiquitin-related proteolysis) and muscle atrophy F-box (MAFbx) levels was noted after treatment with SAC (P < 0.05). Insulin-like growth factor 1(IGF-1) level was increased in the E + S, E + S + Cr, and E + S + A + Cr groups (P < 0.05). While the phosphorylation of 4E-BP1Thr37/46, AktSer473, mTORSer2448, and S6K1Thr389 levels increased after SAC supplementation, phosphorylated muscle ring finger 1 (MuRF-1, an E3-ubiquitin ligase gene) was found to be significantly lower compared with the E group (P Ë‚ 0.05). These results indicate that SAC supplementation improves FSR, insulin, and glycogen levels after exercise. SAC improves protein synthesis by inhibiting the ubiquitin-proteasome pathway and inducing anabolic metabolism.

The effect of dietary amylose/amylopectin ratio on serum and hepatic lipid content and its molecular mechanisms in growing-finishing pigs.

This study was conducted to investigate the effects of dietary amylose/amylopectin ratio (DAR) on serum and hepatic lipid content, luminal short-chain fatty acid (SCFA) concentrations, and the expression of host genes involved in fat and glucose metabolism in liver and mucosa in growing-finishing pigs. Forty-eight Duroc × Landrace × Large White pigs (49.8 ± 2.8 kg) were randomly allocated to low amylose/amylopectin ratio (LR) and high amylose/amylopectin ratio (HR) groups, each group consisting of six replicates (pen) with four pigs per pen. The DAR was 12/88 for LR and 30/70 for HR. Experiment lasted for 67 days. Results showed that, compared with HR group, ingestion of LR significantly increased the liver total lipid and cholesterol concentration (p < .05) and decreased the serum LDL-C concentration (p < .05). The concentration of propionate, butyrate and total SCFAs in caecum digesta was significantly lower in LR group than in HR group (p < .05). We observed a significant increase in glucose transporter 2 (GLUT2), sodium-dependent glucose transporter 1 (SGLT1) gene expression in LR-fed pigs in the jejunum mucosa (p < .01). A decrease in Na+-coupled monocarboxylate transporter (SMCT1) and free fatty acid receptor 3 (FFAR3) expression was found in the ileum mucosa with LR group (p < .05). Ingestion of LR diet significantly decreased the hexokinase (p < .01) and tend to decrease the pyruvate kinase (p = .050) activities in the liver. Meanwhile, the present results indicated that ingestion of LR diet significantly increased the transcription of gluconeogenesis and lipogenic genes such as forkhead box O1 (FOXO1), fatty acid synthetase3 (FAS3) (p < .05). These findings demonstrated that high amylopectin has harmful effects on hepatic lipid deposit through the modulation of the liver Foxo1 signalling and should be avoided from one's diet.

Role of resistant starch on diabetes risk factors in people with prediabetes: Design, conduct, and baseline results of the STARCH trial.

Dietary resistant starch (RS) might alter gastrointestinal tract function in a manner that improves human health, particularly among adults at risk for diabetes. Here, we report the design and baseline results (with emphasis on race differences) from the STARCH trial, the first comprehensive metabolic phenotyping of people with prediabetes enrolled in a randomized clinical trial testing the effect of RS on risk factors for diabetes. Overweight/obese participants (BMI≥27kg/m2 and weight≤143kg), age 35-75y, with confirmed prediabetes were eligible. Participants were randomized to consume 45g/day of RS (RS=amylose) or amylopectin (Control) for 12weeks. The study was designed to evaluate the effect of RS on insulin sensitivity and secretion, ectopic fat, and inflammatory markers. Secondary outcomes included energy expenditure, substrate oxidation, appetite, food intake, colonic microbial composition, fecal and plasma levels of short-chain fatty acids, fecal RS excretion, and gut permeability. Out of 280 individuals screened, 68 were randomized, 65 started the intervention, and 63 were analyzed at baseline (mean age 55y, BMI 35.6kg/m2); 2 were excluded from baseline analyses due to abnormal insulin and diabetes. Sex and race comparisons at baseline were reported. African-Americans had higher baseline acute insulin response to glucose (AIRg measured by frequently sampled intravenous glucose tolerance test) compared to Caucasians, despite having less visceral adipose tissue mass and intrahepatic lipid; all other glycemic variables were similar between races. Sleep energy expenditure was ~90-100kcal/day lower in African-Americans after adjusting for insulin sensitivity and secretion. This manuscript provides an overview of the strategy used to enroll people with prediabetes into the STARCH trial and describes methodologies used in the assessment of risk factors for diabetes. Clinicaltrials.gov identifier: STARCH (NCT01708694). The present study reference can be found here: https://clinicaltrials.gov/ct2/show/NCT01708694. Submission Category: "Study Design, Statistical Design, Study Protocols".

Effects of an amylopectin and chromium complex on the anabolic response to a suboptimal dose of whey protein.

BACKGROUND: Previous research has demonstrated the permissive effect of insulin on muscle protein kinetics, and the enhanced insulin sensitizing effect of chromium. In the presence of adequate whole protein and/or essential amino acids (EAA), insulin has a stimulatory effect on muscle protein synthesis, whereas in conditions of lower blood EAA concentrations, insulin has an inhibitory effect on protein breakdown. In this study, we determined the effect of an amylopectin/chromium (ACr) complex on changes in plasma concentrations of EAA, insulin, glucose, and the fractional rate of muscle protein synthesis (FSR). METHODS: Using a double-blind, cross-over design, ten subjects (six men, four women) consumed 6 g whey protein + 2 g of the amylopectin-chromium complex (WPACr) or 6 g whey protein (WP) after an overnight fast. FSR was measured using a primed, continuous infusion of ring-d5-phenylalanine with serial muscle biopsies performed at 2, 4, and 8 h. Plasma EAA and insulin were assayed by ion-exchange chromatography and ELISA, respectively. After the biopsy at 4 h, subjects ingested their respective supplement, completed eight sets of bilateral isotonic leg extensions at 80% of their estimated 1-RM, and a final biopsy was obtained 4 h later. RESULTS: Both trials increased EAA similarly, with peak levels noted 30 min after ingestion. Insulin tended (p = 0.09) to be higher in the WPACr trial. Paired samples t-tests using baseline and 4-h post-ingestion FSR data separately for each group revealed significant increases in the WPACr group (+0.0197%/h, p = 0.0004) and no difference in the WP group (+0.01215%/hr, p = 0.23). Independent t-tests confirmed significant (p = 0.045) differences in post-treatment FSR between trials. CONCLUSIONS: These data indicate that the addition of ACr to a 6 g dose of whey protein (WPACr) increases the FSR response beyond what is seen with a suboptimal dose of whey protein alone.

Effects of dietary amylose/amylopectin ratio on growth performance, feed utilization, digestive enzymes, and postprandial metabolic responses in juvenile obscure puffer Takifugu obscurus.

The effect of dietary amylose/amylopectin (AM/AP) ratio on growth, feed utilization, digestive enzyme activities, plasma parameters, and postprandial blood glucose responses was evaluated in juvenile obscure puffer, Takifugu obscurus. Five isonitrogenous (430 g kg(-1) crude protein) and isolipidic (90 g kg(-1) crude lipid) diets containing an equal starch level (250 g kg(-1) starch) with different AM/AP ratio diets of 0/25, 3/22, 6/19, 9/16 and 12/13 were formulated. Each experimental diet was fed to triplicate groups (25 fish per tank), twice daily during a period of 60 days. After the growth trial, a postprandial blood response test was carried out. Fish fed diet 6/19 showed best growth, feed efficiency and protein efficiency ratio. Hepatosomatic index, plasma total cholesterol concentration, liver glycogen and lipid content, and gluconokinase, pyruvate kinase and fructose-1,6-bisphosphatase activities were lower in fish fed highest AM/AP diet (12/13) than in fish fed the low-amylose diets. Activities of liver and intestinal trypsin in fish fed diet 3/22 and diet 6/19 were higher than in fish fed diet 9/16 and diet 12/13. Activities of liver and intestinal amylase and intestinal lipase, and starch digestibility were negatively correlated with dietary AM/AP ratio. Fish fed diet 3/22 and diet 6/19 showed higher plasma total amino acid concentration than fish fed the other diets, while plasma urea nitrogen concentration and activities of alanine aminotransferase and aspartate aminotransferase showed the opposite trend. Equal values were found for viscerosomatic index and condition factor, whole body and muscle composition, plasma high-density and low-density lipoprotein cholesterol concentrations, and activities of lipase and hexokinase and glucose-6-phosphatase in liver. Postprandial plasma glucose and triglyceride peak value of fish fed diet 12/13 were lower than in fish fed the low-amylose diets, and the peak time of plasma glucose was later than in fish fed the other diets. Plasma glucose and triglyceride concentrations showed a significant difference at 2 and 4 h after a meal and varied between dietary treatments. According to regression analysis of weight gain against dietary AM/AP ratio, the optimum dietary AM/AP ratio for maximum growth of obscure puffer was 0.25. The present result indicates that dietary AM/AP ratio could affect growth performance and feed utilization, some plasma parameters, digestive enzyme as well as hepatic glucose metabolic enzyme activities in juvenile obscure puffer.

Metabolic and transcriptomic responses of weaned pigs induced by different dietary amylose and amylopectin ratio.

Starch is one of the major dietary energy sources for mammals. However, the nutritional value of starch largely depends on its amylose and amylopectin ratio. In this study, the overall metabolic and transcriptomic responses of weaned pigs fed with different dietary starches were assessed. Sixteen weaned pigs were randomly allotted to two experimental diets containing either of pure cassava starch (CS) or maize starch (MS) as the sole energy source (the amylose-amylopectin ratio were 0.25 and 0.43, respectively). Results indicated that the body weight gain was not affected by different dietary starches. However, a moderate fatty liver was observed in CS-fed group. Long-term ingestion of CS not only increased the total liver fat content, but significantly elevated the liver triglyceride and cholesterol content (P<0.05). In addition, the serum insulin and cholesterol concentrations were both elevated in CS-fed group (P<0.05). Microarray analysis led to the identification of 648 genes differentially expressed in liver (P<0.05), and a lot of them were involved in lipid and carbohydrate metabolism. Additionally, pathway analysis indicated that both the insulin and PPAR signaling pathways were acutely affected by dietary amylose-amylopectin ratio. Long-term ingestion of CS activated the transcription of lipogenic genes such as hmgr and fasn, but decreased the expression of lipolytic genes such as aox1, ppara and fbp. The microarray results correlated well with the measurements of several key enzymes involved in hepatic lipid metabolism. Our results suggested that both the metabolic and transcriptomic responses of weaned pigs were tightly regulated by dietary starch composition, and a high amylose ratio starch (i.e MS) may be more healthful for mammals as the long-term energy source by down-regulation of hepatic lipogenesis and steroidogenesis.

Dietary amylose and amylopectin ratio and resistant starch content affects plasma glucose, lactic acid, hormone levels and protein synthesis in splanchnic tissues.

Experiments were conducted to determine the effects of feeding different starch sources on piglets. Four diets were formulated with maize, brown rice, sticky rice and Hi-Maize 1043 as starch sources, with resistant starch (RS) contents of 2.3%, 0.9%, 0.0%, 20.6%, and amylose and amylopectin ratio of 0.23%, 0.21%, 0.18%, 0.06% respectively. Fifty-six pigs weaned at 28 days of age were randomly assigned to one of the four diets. In Exp. 1, six piglets in each group were fitted with an indwelling jugular catheter. After 25 days of feeding trial, venous blood samples were obtained at time zero and every 1 h for 4 h. In Exp. 2, the remaining piglets were used to determine the effects of different starch sources on the fractional synthesis rate (FSR). The results indicated that feeding the Hi-Maize 1043 diet decreased (p < 0.05) plasma contents of glucose, insulin, lactic acid and T(3), while sticky rice increased plasma contents of glucose and insulin. The insulin contents in piglets fed the sticky rice diet was 69.2 microIU/ml at 1 h post-feeding which was highest among the starch diets. The FSR in the pancreas, spleen, duodenum, jejunum, ileum and colon in the corn group were much higher (p < 0.05) than that in the sticky rice group. These results suggest that RS is potentially beneficial for improving insulin sensitivity in young pigs and that the ratio of amylose and amylopectin have significantly effects on the FSR in splanchnic tissues in weaned piglets. Another finding of this study indicated maize with a ratio of amylose and amylopectin of 0.23 has the best starch sources for pig production.

Effect of starch and sucrose on dental biofilm formation and on root dentine demineralization.

The cariogenicity of starch alone or in combination with sucrose is controversial and the effect on dentine demineralization and on the dental biofilm formed has not been explored under controlled conditions. A crossover, single-blind study was conducted in four steps of 14 days each, during which 11 volunteers wore palatal appliance containing 10 slabs of root dentine to which the following treatments were applied extraorally: 2% starch gel-like solution (starch group); 10% sucrose solution (sucrose group); a solution containing 2% starch and 10% sucrose (starch + sucrose group), or 2% starch solution followed by 10% sucrose solution (starch --> sucrose group). On the 14th day of each phase the biofilms were collected for biochemical and microbiological analyses, and dentine demineralization was assessed by hardness. A higher demineralization was found in dentine exposed to sucrose and starch sucrose combinations than to starch alone (p < 0.01), but the sucrose-containing groups did not differ significantly from each other (p > 0.05). The concentrations of soluble and insoluble extracellular polysaccharides (EPS), and the proportion of insoluble EPS, were lower in the biofilm formed in presence of starch (p < 0.01) than in those formed in the presence of sucrose or sucrose/starch combinations; however, no significant difference was observed among the groups containing sucrose (p > 0.05). RNA was successfully isolated and purified from in situ biofilms and only biofilms formed in response to sucrose and starch/sucrose combinations showed detectable levels of gtfB and gtfC mRNA. The findings suggest that the combination of starch with sucrose may not be more cariogenic to dentine than sucrose alone.

Amylopectin induces fumonisin B1 production by Fusarium verticillioides during colonization of maize kernels.

Fusarium verticillioides, a fungal pathogen of maize, produces fumonisin mycotoxins that adversely affect human and animal health. Basic questions remain unanswered regarding the interactions between the host plant and the fungus that lead to the accumulation of fumonisins in maize kernels. In this study, we evaluated the role of kernel endosperm composition in regulating fumonisin B1 (FB1) biosynthesis. We found that kernels lacking starch due to physiological immaturity did not accumulate FB1. Quantitative polymerase chain reaction analysis indicated that kernel development also affected the expression of fungal genes involved in FB1 biosynthesis, starch metabolism, and nitrogen regulation. A mutant strain of F. verticillioides with a disrupted a-amylase gene was impaired in its ability to produce FB1 on starchy kernels, and both the wild-type and mutant strains produced significantly less FB1 on a high-amylose kernel mutant of maize. When grown on a defined medium with amylose as the sole carbon source, the wild-type strain produced only trace amounts of FB1, but it produced large amounts of FB1 when grown on amylopectin or dextrin, a product of amylopectin hydrolysis. We conclude that amylopectin induces FB1 production in F. verticillioides. This study provides new insight regarding the interaction between the fungus and maize kernel during pathogenesis and highlights important areas that need further study.

Immune stimulating properties of a novel polysaccharide from the medicinal plant Tinospora cordifolia.

An alpha-D-glucan (RR1) composed of (1-->4) linked back bone and (1-->6) linked branches with a molecular mass of >550 kDa and exhibiting unique immune stimulating properties is isolated and characterized from the medicinal plant Tinospora cordifolia. This novel polysaccharide is noncytotoxic and nonproliferating to normal lymphocytes as well as tumor cell lines at 0-1000 microg/ml. It activated different subsets of the lymphocytes such as natural killer (NK) cells (331%), T cells (102%), and B cells (39%) at 100 microg/ml concentration. The significant activation of NK cells is associated with the dose-dependent killing of tumor cells by activated normal lymphocytes in a functional assay. Immune activation by RR1 in normal lymphocytes elicited the synthesis of interleukin (IL)-1beta (1080 pg/ml), IL-6 (21,833 pg/ml), IL-12 p70 (50.19 pg/ml), IL-12 p40 (918.23 pg/ml), IL-18 (27.47 pg/ml), IFN- gamma (90.16 pg/ml), tumor necrosis factor (TNF)-alpha (2225 pg/ml) and monocyte chemoattractant protein (MCP)-1 (2307 pg/ml) at 100 microg/ml concentration, while it did not induce the production of IL-2, IL-4, IL-10, interferon (IFN)-alpha and TNF-beta. The cytokine profile clearly demonstrates the Th1 pathway of T helper cell differentiation essential for cell mediated immunity, with a self-regulatory mechanism for the control of its overproduction. RR1 also activated the complements in the alternate pathway, demonstrated by a stepwise increase in C3a des Arg components. Incidentally, RR1 stimulation did not produce any oxidative stress or inducible nitric oxide synthase (iNOS) in the lymphocytes or any significant increase in nitric oxide production. The water solubility, high molecular mass, activation of lymphocytes especially NK cells, complement activation, Th1 pathway-associated cytokine profile, together with a low level of nitric oxide synthesis and absence of oxidative stress confer important immunoprotective potential to this novel alpha-D-glucan.

Effect of nonwaxy and waxy sorghum on growth, carcass traits, and glucose and insulin kinetics of growing-finishing barrows and gilts.

Two experiments were conducted to determine the effect of nonwaxy (amylose and amylopectin starch) or waxy (amylopectin starch) sorghum on growth, carcass traits, and glucose and insulin kinetics of pigs. In Exp. 1 (95-d), 60 crossbred barrows or gilts (initial and final BW of 24 and 104 kg) were allotted to three treatments with five replications of four pigs per replicate pen in a randomized complete block design. The dietary treatments for Exp. 1 were 1) corn-soybean meal (C-SBM) diet, 2) sorghum-SBM (red pericarp, non-waxy), and 3) sorghum-SBM (red pericarp, waxy). In Exp. 2, 28 crossbred barrows (initial and final BW of 24 and 64 kg) were allotted to two treatments with three replications of four or five pigs per replicate pen in a randomized complete block design. Growth data were collected for 49 d, and then 20 barrows were fitted with jugular catheters, and then a glucose tolerance test (500 mg glucose/kg BW), an insulin challenge test (0.1 IU of porcine insulin/kg BW), and a feeding challenge were conducted. The dietary treatments for Exp. 2 were 1) sorghum-SBM (white pericarp, nonwaxy) and 2) sorghum-SBM (white pericarp, waxy). In Exp. 1, ADG (P = 0.10) and ADFI (as-fed basis; P = 0.02) were increased (P = 0.10) and gain:feed was decreased (P = 0.04) in pigs fed the sorghum-SBM diets relative to those fed the C-SBM diet. These responses may have resulted from the lower energy content of sorghum relative to corn. Plasma NEFA concentration (collected after a 16-h fast on d 77) was decreased (P = 0.08) in pigs fed the waxy sorghum-SBM diet relative to those fed the nonwaxy sorghum-SBM diet. Kilograms of carcass fat was decreased (P = 0.07) in pigs fed the waxy sorghum-SBM diet relative to those fed the nonwaxy sorghum-SBM diet. In Exp. 2, there was no effect (P = 0.57 to 0.93) of sorghum starch type on growth performance by pigs. During the glucose tolerance and insulin challenge tests, there were no effects (P = 0.16 to 0.98) of diet on glucose or insulin kinetics. During the feeding challenge, glucose (P = 0.02) and plasma urea N (P = 0.06) area under the response curves from 0 to 90 min were decreased in pigs fed the waxy sorghum-SBM diet. Feeding waxy sorghum had minimal effects on growth and carcass traits relative to pigs fed corn or nonwaxy sorghum. Waxy sorghum vs. nonwaxy sorghum had no effect on glucose or insulin kinetics in pigs.

Intravesicular glucose modulates magnesium2+ transport in liver plasma membrane from streptozotocin-treated rats.

Plasma membrane vesicles purified from livers of 4-week-old streptozotocin-injected diabetic rats present an increased basal and cation-stimulated magnesium (Mg)2+ transport as compared with vesicles purified from age-matched nondiabetic animals. Furthermore, diabetic basolateral membranes are unable to accumulate extravesicular Mg2+ in exchange for intravesicular sodium (Na)+. Loading diabetic vesicles with varying concentrations of D-glucose, in addition to Mg2+, renormalizes basal and Na+- or calcium (Ca)2+-induced Mg2+ extrusion in a dose-dependent manner, but does not restore Na+/Mg2+ exchanger reversibility. A similar effect on Mg2+ extrusion is observed when D-glucose is replaced with 2-deoxy-glucose, amylopectin, or glycogen. The loading with 3-methyl-O-glucose or L-glucose, instead, affects basal and Na+-dependent Mg2+ extrusion, but not Ca2+-dependent Mg2+ fluxes. In contrast, loading the vesicles with hexoses other than glucose or varying extravesicular glucose concentration from 5 to 20 mmol/L does not modify basal or cation-stimulated Mg2+ fluxes. Taken together, these data indicate that basal and cation-stimulated Mg2+ transport across the hepatocyte plasma membrane is altered under diabetic conditions as a result of a decrease in intravesicular (intracellular) glucose.