MyoD Over-Expression Rescues GST-bFGF Repressed Myogenesis

During embryogenesis, basic fibroblast growth factor (bFGF) is released from neural tube and myotome to promote myogenic fate in the somite, and is routinely used for the culture of adult skeletal muscle (SKM) stem cells (MuSC, called satellite cells). However, the mechanism employed by bFGF to promote SKM lineage and MuSC proliferation has not been analyzed in detail. Furthermore, the question of if the post-translational modification (PTM) of bFGF is important to its stemness-promoting effect has not been answered. In this study, GST-bFGF was expressed and purified from E.coli, which lacks the PTM system in eukaryotes. We found that both GST-bFGF and commercially available bFGF activated the Akt-Erk pathway and had strong cell proliferation effect on C2C12 myoblasts and MuSC. GST-bFGF reversibly compromised the myogenesis of C2C12 myoblasts and MuSC, and it increased the expression of Myf5, Pax3/7, and Cyclin D1 but strongly repressed that of MyoD, suggesting the maintenance of myogenic stemness amid repressed MyoD expression. The proliferation effect of GST-bFGF was conserved in C2C12 over-expressed with MyoD (C2C12-tTA-MyoD), implying its independence of the down-regulation of MyoD. In addition, the repressive effect of GST-bFGF on myogenic differentiation was almost totally rescued by the over-expression of MyoD. Together, these evidences suggest that (1) GST-bFGF and bFGF have similar effects on myogenic cell proliferation and differentiation, and (2) GST-bFGF can promote MuSC stemness and proliferation by differentially regulating MRFs and Pax3/7, (3) MyoD repression by GST-bFGF is reversible and independent of the proliferation effect, and (4) GST-bFGF can be a good substitute for bFGF in sustaining MuSC stemness and proliferation.

[Establishment and application of a multilocus sequence typing assay for Corynebacterium striatum]

Objective: To establish a multilocus sequence typing (MLST) assay for Corynebacterium (C.) striatum, explore the population structure and evolution relationship of clinical isolates of C. striatum. Methods: Seven housekeeping genes (gyrA, gyrB, hsp65, sodA, secA1, rpoB, 16S rRNA) were amplified with PCR by using self-designed specific primers and sequenced. Then, the sequences were assembled with software SeqMan. The gene diversity and gene recombination characteristics were evaluated by using software DnaSP 5.10.01 and Splits tree 4.14.2. The phylogenetic tree and the minimum spanning tree were constructed based on the sequence types (ST) characteristics by using software MEGA 7.0.14 and BioNumerics, respectively. In addition, the genetic evolutionary relationship among STs were analyzed by using software eBURST 3.0. Results: The expected amplification products of seven sites selected in all the test strains were obtained. Splits tree showed that the clustering of all C. striatum strains was consistent, suggesting that gene recombination is the potential driving force for the evolution of C. striatum. All of the 344 C.striatum strains were divided into 72 STs by MLST and 85.7% of the strains formed clonal complexes. CC19 was the predominant clonal complex, whereas ST16 in the clonal complex was detected in the most strains. ST had a certain geographic clustering and a certain correlation with the isolation time. Conclusions: C. striatum showed high genetic diversity in China and CC19 was the predominant clonal complex. The MLST assay established in this study can be used for the typing of C. striatum, but further improvement is needed.

Plasma total antioxidant capacity (TAC) in obese Malaysian subjects

INTRODUCTION

There is a pressing need to better understand the complex biochemical pathways that lead to the pathogenesis of obesity. Increased oxidative stress and decreased antioxidant capacity have been identified to be associated with obesity. Therefore, the objectives of this study were to determine the plasma total antioxidant capacity (TAC) levels of Malaysian subjects and to evaluate its potential association with obesity and related anthropometric measurements.

METHODS

Plasma TAC of 362 multi-ethnic Malaysian subjects from the Kampar Health Clinic (138 males, 224 females; 124 ethnic Malays, 152 Chinese, 86 Indians; 192 non-obese, 170 obese) was measured using Trolox equivalent antioxidant capacity (TEAC) 96-well plate assay.

RESULTS

Plasma TAC was significantly lower in obese subjects (M +/- SE = 292 +/- 10.4 micromol/L) compared to non-obese subjects (397 +/- 8.58 micromol/L), whereas it was significantly higher in males and those in the 21-30 age group. Those with salty food preference and practising a strict vegetarian diet also had significantly higher plasma TAC. However, no association was found for other dietary habits (coffee intake) and lifestyle factors (physical activity, smoking). Plasma TAC was also significantly negatively correlated with diastolic blood pressure, waist and hip circumferences, weight, body mass index, total body fat, % subcutaneous fat, visceral fat level, resting metabolism and % skeletal muscle.

CONCLUSION

Plasma TAC was found to be associated with obesity, strict vegetarian practice, salty food preference and all obesity anthropometric indicators, except systolic blood pressure and pulse rate. Obese people have decreased plasma TAC indicating a compromised systemic antioxidant defence and increased oxidative stress.

Prevalence of melanocortin receptor 4 (MC4R) V103I gene variant and its association with obesity among the Kampar Health Clinic cohort, Perak, Malaysia

This study investigated the prevalence of the Melanocortin receptor 4 (MC4R) V1031 gene variant and its association with obesity among a cohort of 254 patients (101 males; 118 obese) attending the Kampar Health Clinic. Genotyping revealed the mutated I allele frequency of 0.02, no homozygous mutated (II), and similar distribution of V and I alleles across BMI groups, genders and ethnic groups. No significant difference was found for the means of anthropometric measurements between alleles. Prevalence of this gene variant among the Malaysian cohort was similar with previous populations (2-4% of mutated allele carrier), but was not associated with obesity.

No association of peptide tyrosine-tyrosine (PYY) gene R72T variant with obesity in the Kampar Health Clinic cohort, Malaysia

INTRODUCTION

Peptide Tyrosine-Tyrosine (PYY) is a 36-amino acid peptide hormone released post-prandially from the endocrine cells in the intestinal tract to suppress pancreatic secretions and eventually reduce appetite. The R72T variant in the PYY gene (rs1058046) has been associated with increased susceptibility to obesity. Therefore, the objective of this study was to investigate the association of this variant with obesity and its related anthropometric measurements among the Kampar Health Clinic cohort, Malaysia.

METHODOLOGY

A total of 197 (78 males, 119 females; 98 non-obese, 99 obese) subjects were recruited by convenience sampling and anthropometric measurements were taken. Genotyping was performed using StuI Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP), revealing 61 RR, 94 RT and 42 TT subjects.

RESULTS

Most of the obese subjects had the RT genotype (50.5%), while only 18.2% were TT. PYY R72T genotypes and alleles had no association with obesity (p = 0.535; 0.074, respectively), gender (p = 0.767; p = 0.100, respectively) but were associated with ethnicity (p = 0.003; p = 0.002, respectively). Among the 13 anthropometric measurements taken, significant difference was only found in Waist Circumference (WC) and Visceral Fat Level (VFL) among the alleles, suggesting that subjects with T allele will have an increment of 1.82 cm in WC and 1.32% in VFL.

CONCLUSION

The R72T variant in PYY gene was not associated with obesity and most of its related anthropometric measurements. This suggests that other genes and/or environmental factors like dietary habits and lifestyle factors may be the contributors of obesity.

[Purification and biochemical characterization of high-molecular-weight-glutenin subunits 14 and 15]

The high molecular weight glutenin subunits 14 and 15 were purified from cultivars of bread wheat (Triticum aestivum) Xiaoyan 6 by preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) appled a new method for visualizing protein in gels. N-terminal amino acid sequences were homologous comparing with other High-Molecular-Weight glutenin subunits. The result suggested that they were basic protein analyzed by two-dimensional electrophoresis of IEF(Isoelectric Focussing) x SDS-PAGE and NEPHGE(Non-Equilibrium PI-gradient Electrophoresis) x SDS-PAGE.

Selective expression of transient outward currents in different types of acutely isolated hippocampal interneurons

1. Voltage-dependent outward currents in CA1 interneurons were studied with the use of whole cell voltage-clamp techniques. Tissue slices containing strata lacunosum-moleculare and radiatum (L-M-R regions) of the hippocampal CA1 region were prepared. Neurons were then isolated from these tissue slices with the use of an acute dissociation procedure. The morphologies of the isolated neurons were distinct from those of pyramidal cells and correlated with those of interneurons identified in the L-M-R regions after immunohistochemical stainings. 2. Total outward currents were elicited from the isolated cells by depolarization steps applied after a 300-ms hyperpolarization prepulse to 100 mV from a holding potential of 50 mV. Delayed outward currents were obtained by intercalating a 120-ms step at 55 mV between the hyperpolarizing prepulse and the depolarization. The intercalating step served to inactivate transient outward currents. Transient outward current were isolated by subtracting the delayed outward currents from the total outward currents. 3. Interneurons were subgrouped on the basis of their ability to produce transient outward current in response to the above protocol. 4. The two groups of interneurons possessed distinct morphological features. Cells producing transient outward currents had polygonal-shaped somata with thick primary processes that gave rise to smaller secondary processes at a short distance from the soma. Interneurons without activatable transient outward currents had somata that were not polygonal and they had more slender primary dendritic processes. 5. These results suggest that interneurons in the L-M-R regions can be divided into two groups on the basis of the presence or absence of voltage-dependent transient outward currents. The two groups of cells differentiated on this basis also have distinguishable morphological traits. The difference in the properties of the outward current may be a factor contributing to the variation in the firing pattern of recorded interneurons reported in previous studies.

Extracellular Mg2+ modulates intracellular Ca2+ in acutely isolated hippocampal CA1 pyramidal cells of the guinea-pig

Using digital imaging microscopy and fluorescent probes, isolated hippocampal CA1 pyramidal neurons of the guinea-pig were used to examine the roles of [Mg2+]o in regulation of [Ca2+]i and [Mg2+]i. Low extracellular Mg ([Mg2+]o) (0.3 mM) significantly increased [Ca2+]i compared to 1.2 and 4.8 mM [Mg2+]o. In contrast, [Mg2+]i levels remained relatively constant, irrespective of alterations of [Mg2+]o. The sustained rise in [Ca2+]i induced by low [Mg2+]o was reduced 70% by 1 microM verapamil and 42% by 1 mM Ni2+, and completely abolished by 5 mM Ni2+. The data suggest that [Mg2+]o regulates [Ca2+]i in hippocampal neurons, probably by modulating Ca2+ entry via voltage-sensitive Ca2+ channels, which may play important roles in epileptogenesis, memory, learning and brain trauma. Furthermore, the results demonstrate that intracellular Mg2+ concentration does not follow passively the concentration of Mg2+ in the extracellular solution.

Neurochemical basis of interleukin 2-modified discrimination behaviour

We trained one group of rats to discriminate 0.8 mg/kg intraperitoneal (i.p.) d-amphetamine from 1 ml/kg saline and the other to discriminate 0.3 mg/kg i.p. (+/-)-ethylketocyclazocine (EKC) from saline. Recombinant human interleukin 2 (rIL-2), 2 x 10(6) U/kg (or 8.2 nmol/kg) given i.p. 1 h prior to tests, potentiated responses elicited by 0.4 mg/kg d-amphetamine. This potentiation of d-amphetamine responses was suppressed by the opioid receptor antagonist naloxone (1 mg/kg) when administered i.p. together with IL-2. IL-2 (4 x 10(6) U/kg) alone produced EKC-like responses in the EKC-trained animals. The cytokine also potentiated 0.1 mg/kg EKC responses at 2 x 10(6) U/kg, an action that was suppressed by 1 mg/kg naloxone. Data from the present study show that IL-2 exerts the same neurochemical action as that previously observed with IFN-alpha for both d-amphetamine and EKC discrimination in rats.

The opioid mechanism of interferon-alpha action

Rats were trained to discriminate the opioid receptor agonist ethylketocyclazocine (EKC) (0.3 mg/kg body weight, intraperitoneally) from saline. Interferon-alpha (IFN-alpha), when substituted for EKC, elicited a dose-related increase in EKC-like responses. This generalization of EKC responses was blocked by the opioid antagonist naloxone (1 mg/kg). Potentiation of responses to a low dose (0.1 mg/kg) of EKC by IFN-alpha (1 x 10(6) U/kg or 0.22 nmol/kg) was also observed. Data thus indicate the involvement of opioid neurons on the action of IFN-alpha. d-Amphetamine (0.8 mg/kg) was shown to potentiate both EKC (0.1 mg/kg) and IFN-alpha (1 x 10(6) U/kg). The present study confirms our previously proposed opioid-mediated dopaminergic mechanism of IFN-alpha.