Novel metabolic and physiological functions of branched chain amino acids: a review

It is widely known that branched chain amino acids（BCAA） are not only elementary components for building muscle tissue but also participate in increasing protein synthesis in animals and humans. BCAA（isoleucine, leucine and valine） regulate many key signaling pathways, the most classic of which is the activation of the m TOR signaling pathway. This signaling pathway connects many diverse physiological and metabolic roles. Recent years have witnessed many striking developments in determining the novel functions of BCAA including：（1） Insufficient or excessive levels of BCAA in the diet enhances lipolysis.（2） BCAA, especially isoleucine, play a major role in enhancing glucose consumption and utilization by up-regulating intestinal and muscular glucose transporters.（3）Supplementation of leucine in the diet enhances meat quality in finishing pigs.（4） BCAA are beneficial for mammary health, milk quality and embryo growth.（5） BCAA enhance intestinal development, intestinal amino acid transportation and mucin production.（6） BCAA participate in up-regulating innate and adaptive immune responses.In addition, abnormally elevated BCAA levels in the blood（decreased BCAA catabolism） are a good biomarker for the early detection of obesity, diabetes and other metabolic diseases. This review will provide some insights into these novel metabolic and physiological functions of BCAA.

Inhibitive effects of glucose and free fatty acids on proliferation of human vascular endothelial cells in vitro

s To investigate the effects of glucose and free fatty acids (FFAs) on the proliferation and cell cycle of human vascular endothelial cells in vitro , and to examine whether the combined presence of elevated FFAs and glucose may cross amplify their individual injurious effects Methods Cultured human vascular endothelial cells (ECV304) were incubated with various concentrations of glucose and/or FFAs (palmitate and/or oleate) for 24-96 h Morphologic alterations were observed using a phase contrast microscope and an electron microscope Inhibition of proliferation was measured by a colorimetric 3 [4, 5 dimethyl thiazol 2 yl] 2, 5 diphenyltetrazolium bromide (MTT) assay Cell viability was determined using trypan blue exclusion Distribution of cells along phases of the cell cycle was analyzed by flow cytometry Results Glucose 15 or 30 mmol/L, palmitate (PA) 0 25 or 0 5 mmol/L, and oleate (OA) 0 5 mmol/L inhibited proliferation and accelerated death of endothelial cells in a dose and time dependent manner After treatment with elevated glucose and/or FFAs, the G 0/G 1 phase cells increased, whereas S phase cells decreased, suggesting that high glucose and/or FFAs mainly arrested endothelial cells at G 0/G 1 phase The inhibitive rates of proliferation and population of dead cells in endothelial cells incubated with glucose plus FFAs (glucose 30 mmol/L+PA 0 25 mmol/L, glucose 30 mmol/L+OA 0 5 mmol/L, glucose 30 mmol/L+PA 0 25 mmol/L+OA 0 5 mmol/L) increased more markedly than those treated with high glucose or FFAs (PA and/or OA) alone Conclusion Both high ambient glucose and FFAs can inhibit proliferation and accelerate death of endothelial cells in vitro These changes were cross amplified in the combined presence of high levels of glucose and FFAs

Colorimetric detection of glucose using a boronic acid derivative receptor attached to unmodified AuNPs

A simple, cheap and non-enzymatic colorimetric strategy for glucose detection has been designed based on the interactions between a phenylboronic acid （PBA） derivative, which is coupled with gold nanoparticles （AuNPs） as the colorimetric reporters, and glucose. The PBA-AuNPs hybrid system proposed here exhibits ordered photochemistry behaviors upon the addition of glucose at different pH values. There are two linear regions of glucose concentration for the glucose sensor at different pH values, i.e., between 0.1 mmol/L and 9.8 mmol/L at pH 6 with the detection limit of 64μmol/L and between 0 and 6.5 mmol/L with the detection limit of 48 μmol/L at pH 9, respectively. To test the practicality of the sensor system, we also applied this assay to detect a glucose sample in the artificial saliva.

Protective Effect of Salvianolic Acid A on Brain Endothelial Cells after Treatment with Deprivation and Reperfusion of Oxygen-glucose

Objective Salvianolic acid A（SAA） has a significant protective effect on ischemia/reperfusion injury of brain. However, it is not clear for SAA to exert its cerebral protection by targeting at the microvascular endothelial cells of blood brain barrier（BBB）. Our previous study demonstrated that SAA could hardly pass through the BBB. This present study was therefore designed to investigate the protective effect of SAA on brain microvascular endothelial cells（BMECs） induced by deprivation and reperfusion with oxygen-glucose. Methods Rat BMECs were treated with oxygen glucose deprivation（OGD）, followed by reperfusion（OGD/R）. Cell viability was assessed by MTT and the content of reactive oxygen species（ROS） in cells after OGD/R in the absence or presence of SAA. GC-MS based metabolomic platform was applied to evaluate the regulation of SAA on the cellular metabolic perturbation induced by OGD/R. Results OGD/R significantly increased the production of intracellular reactive oxygen species（ROS）, and decreased the activity of cells. SAA significantly reduced ROS and improve the cell viability. Metabolomic study revealed distinct perturbation of metabolic pathways of energy metabolism in the BMEC induced by OGD/R, while SAA significantly regulated the perturbed metabolism involved in energy metabolism pathways, especially for intermediates in TCA cycle. Conclusion SAA shows protective effects on BMECs involved in central nervous system.

Maintaining the metabolic homeostasis of Helicobacter pylori through chronic hyperglycemia in diabetes mellitus:A hypothesis

Helicobacter pylori(H.pylori)infection occurs in almost half of the world's population,most of whom are merely carriers of this microorganism.H.pylori is shown to be detected more frequently in patients with diabetes mellitus(DM)than in the general population,which is accompanied by a significantly increased risk of developing H.pylori-associated diseases.In addition,eradication therapy shows a low efficiency for H.pylori infection in patients with DM.There is a relationship between the level of chronic hyperglycemia and a higher detection rate of H.pylori as well as a lower efficiency of eradication therapy in patients with DM.The exact mechanisms of these phenomena are unknown.The authors make a hypothesis that explains the relationship between chronic hyperglycemia and the increased detection rate of H.pylori,as well as the mechanisms contributing to the improved survival of this bacterium in patients with DM during eradication therapy.

Preliminary evaluation of five elephant grass cultivars harvested at different time for sugar production

Five elephant grass cultivars, Pennisetum purpureum, cv. Huanan （Huanan）, P. purpureum, cv. N51 （N51）, P. purpureum, cv. Sumu No. 2 （Sumu-2）, （ Penniseturn americanum x P. purpureum ） x P. purpureum cv. Guimu No. 1 （Guimu-1） and P. americanum cv. Tift23A x P. purpureum cv. Tilt NS1 （Hybrid Pennisetum）, at three harvest stages were studied. With dilute sulfuric acid pretreatment followed by enzymatic hydrolysis, it is found that cel- lulose conversion of the five elephant grass cultivars harvested in August and September is higher than that har- vested in October. The cellulose conversion for elephant grass cultivars harvested in August and September follows an order of Hybrid Pennisetum 〉 Sumu-2 〉 Huanan 〉 Guimu-1 〉 N51. This may be explained by the fact that lignification is gradually strengthened with time, inhibiting degradation of cellulose and hemicellulose. Moreover, cellulose conversions of Hybrid Pennisetum, Sumu-2 and Huanan harvested in August and September are higher based on hierarchical clustering results.

Association of GYS1 and β_3-AR gene with postprandial hyperglycemia and serum uric acid in type 2 diabetes mellitus

Objective To determine the relationships of Met416Val and XbaI polymorphism of muscle glycogen synthase (GYS1) gene and Trg64Arg variant of the β 3 adrenergic receptor (β 3 AR) gene with type 2 diabetes mellitus (DM) and its intermediate phenotypes in the Chinese population Methods Polymerase chain reaction oligonucleotide ligation assay and restriction fragment length polymorphism assay were used to evaluate the GYS1 and β 3 AR gene polymorphisms in 102 pairs of case control Chinese spouses Results Subjects with Met416Val variant had a significantly higher 2 hour post glucose level than subjects without this variant had in diabetic group ( P =0 032) The Met416Val polymorphism of GYS1 gene was not significantly associated with the risk of type 2 DM (adjusted OR=1 67; 95% CI: 0 73-3 81, P =0 223) Subjects with Trp64Arg variant had a significantly higher serum uric acid level than subjects without this variant had in diabetic group ( P =0 034) The combination of BMI and Arg64 allele carrier of the β 3 AR gene increased the diabetic risk over four fold (adjusted OR=4 00; 95%CI: 1 53-10 45, P =0 005) Conclusions In the Chinese population, Met416Val polymorphism is identified in a subgroup of diabetic subjects with high 2 hour post glucose It will explain why some diabetic patients appear to be genetically predisposed to developing high postpradial glucose level The presence of the Arg64 allele in the β 3 AR gene may predispose patients to higher serum uric acid level

Dehydration of glucose into 5-hydroxymethylfurfural in SO_3H-functionalized ionic liquids

The continuous dehydration of D-glucose into 5-hydroxymethylfurfural（HMF） was carried out under mild conditions,using SO3H-functionalized acidic ionic liquids as catalysts and H2O-4-methyl-2-pentanone（MIBK） biphasic system as solvent.High glucose conversion of 97.4% with HMF yield of 75.1%was obtained at 120 8C for 360 min,also,small amounts of levulinic acid（LA） and formic acid were generated.Generally,the dosage of catalyst and the initial content of glucose influenced the reaction significantly; the HMF selectivity decreased with the excessive elevation of temperature and prolonging of time; and water content in the system had a negative effect on the reaction.The ionic liquid catalyst could be recycled and exhibited constant activity for five successful runs.This paper provided a new strategy for HMF production from glucose.

Improved thromboresistance and analytical performance of intravascular amperometric glucose sensors using optimized nitric oxide release coatings

In this work, nitric oxide （NO） release coatings designed for intravenous amperometric glucose sensors are optimized through the use ofa polylactic acid （PLA） layer doped with a lipophilic diazeniumdiolated species that releases NO through a proton-driven mechanism. An Elast-Eon E2As polyurethane coating is used to both moderate NO release from the sensor surface and increase the sensor＇s linear detection range toward glucose. These sensors were evaluated for thromboresistance and in vivo glucose performance through implantation in rabbit veins. By maintaining NO flux on a similar scale to endogenous endothelial cells, implanted glucose sensors exhibited reduced surface clot formation which enables more accurate quantitative glucose measurements continuously. An in vivo time trace of implanted venous sensors demonstrated glucose values that correlated well with the discrete measurements of blood samples on a benchtop point-of-care sensor-based instrument. The raw measured currents from the implanted glucose sensors over 7 h time periods were converted to glucose concentration through use of both a one-point in vivo calibration and a calibration curve obtained in vitro within a bovine serum solution. Control sensors, assembled without NO release functionality, exhibit distinctive surface clotting over the 7 h in vivo implantation period.

Muscadine or amla extracts standardized to ellagic acid content ameliorate glucolipotoxicity associatedβ-cell dysfunction via inhibition of IL-1βand improved insulin secretion

Glucolipotocixity induces IL-1βsecretion which impairs pancreaticβ-cell insulin secretion.Ellagic acid and urolithin A have strong anti-inflammatory effect on cells.Muscadine and amla are very good sources of ellagic acid.The present study examined the effect of ellagic acid,ellagic acid-rich muscadine or amla extract,or urolothin A on inflammation inβcells under glucolipotoxic conditions.Rat NIT-1βcells were incubated in glucolipotoxic conditions(33.3 mM glucose,250μM palmitic acid or 33.3 mM glucose+250μM palmitic acid with or without ellagic acid,ellagic acid-rich muscadine or amla extracts standardized to its ellagic acid content,or urolithin A).Inflammatory status was evidenced by ELISA analysis of insulin and IL-1βsecretion.Ellagic acid-rich muscadine or amla extracts dose-dependently stimulated insulin secretion and down-regulated IL-1βbetter than pure ellagic acid,or urolithin A.Urolithin A did not statistically stimulate insulin secretion and did not inhibit IL-1β.

Enhanced photoelectrochemical and photocatalytic activities of CdS nanowires by surface modification with MoS_2 nanosheets

Nanocomposites composed of one-dimensional（1D） CdS nanowires（NWs） and 1 T-MoS2 nanosheets have been fabricated through a two-step solvothermal process. 5 mol% of MoS2 loading results in the best optical properties,photoelectrochemical（PEC） as well as photocatalytic activities for hydrogen evolution reaction（HER）. Compared with pure CdS NWs, the optimized nanocomposite shows 5.5 times enhancement in photocurrent and 86.3 times increase for HER in the presence of glucose and lactic acid as hole scavengers.The enhanced PEC and HER activities are attributed to the intimate contact between MoS2 and CdS that efficiently enhances charge carrier separation. In addition, ultrafast transient absorption（TA） measurements have been used to probe the charge carrier dynamics and gain deeper insight into the mechanism behind the enhanced PEC and photocatalytic performance.