Leptin administration improves skeletal muscle insulin responsiveness in diet-induced insulin-resistant rats

In addition to suppressing appetite, leptin may also modulate insulin secretion and action. Leptin was administered here to insulin-resistant rats to determine its effects on secretagogue-stimulated insulin release, whole body glucose disposal, and insulin-stimulated skeletal muscle glucose uptake and transport. Male Wistar rats were fed either a normal (Con) or a high-fat (HF) diet for 3 or 6 mo. HF rats were then treated with either vehicle (HF), leptin (HF-Lep, 10 mg. kg(-1). day(-1) sc), or food restriction (HF-FR) for 12-15 days. Glucose tolerance and skeletal muscle glucose uptake and transport were significantly impaired in HF compared with Con. Whole body glucose tolerance and rates of insulin-stimulated skeletal muscle glucose uptake and transport in HF-Lep were similar to those of Con and greater than those of HF and HF-FR. The insulin secretory response to either glucose or tolbutamide (a pancreatic beta-cell secretagogue) was not significantly diminished in HF-Lep. Total and plasma membrane skeletal muscle GLUT-4 protein concentrations were similar in Con and HF-Lep and greater than those in HF and HF-FR. The findings suggest that chronic leptin administration reversed a high-fat diet-induced insulin-resistant state, without compromising insulin secretion.     

Portal vein hypoglycemia is essential for full induction of hypoglycemia-associated autonomic failure with slow-onset hypoglycemia

Antecedent hypoglycemia leads to impaired counterregulation and hypoglycemic unawareness. To ascertain whether antecedent portal vein hypoglycemia impairs portal vein glucose sensing, thereby inducing counterregulatory failure, we compared the effects of antecedent hypoglycemia, with and without normalization of portal vein glycemia, upon the counterregulatory response to subsequent hypoglycemia. Male Wistar rats were chronically cannulated in the carotid artery (sampling), jugular vein (glucose and insulin infusion), and mesenteric vein (glucose infusion). On day 1, the following three distinct antecedent protocols were employed: 1) HYPO-HYPO: systemic hypoglycemia (2.52 +/- 0.11 mM); 2) HYPO-EUG: systemic hypoglycemia (2.70 +/- 0.03 mM) with normalization of portal vein glycemia (portal vein glucose = 5.86 +/- 0.10 mM); and 3) EUG-EUG: systemic euglycemia (6.33 +/- 0.31 mM). On day 2, all groups underwent a hyperinsulinemic-hypoglycemic clamp in which the fall in glycemia was controlled so as to reach the nadir (2.34 +/- 0.04 mM) by minute 75. Counterregulatory hormone responses were measured at basal (-30 and 0) and during hypoglycemia (60-105 min). Compared with EUG-EUG, antecedent hypoglycemia (HYPO-HYPO) significantly blunted the peak epinephrine (10.44 +/- 1.35 vs. 15.75 +/- 1.33 nM: P = 0.01) and glucagon (341 +/- 16 vs. 597 +/- 82 pg/ml: P = 0.03) responses to next-day hypoglycemia. Normalization of portal glycemia during systemic hypoglycemia on day 1 (HYPO-EUG) prevented blunting of the peak epinephrine (15.59 +/- 1.43 vs. 15.75 +/- 1.33 nM: P = 0.94) and glucagon (523 +/- 169 vs. 597 +/- 82 pg/ml: P = 0.66) responses to day 2 hypoglycemia. Consistent with hormonal responses, the glucose infusion rate during day 2 hypoglycemia was substantially elevated in HYPO-HYPO (74 +/- 12 vs. 49 +/- 4 micromol x kg(-1) x min(-1); P = 0.03) but not HYPO-EUG (39 +/- 7 vs. 49 +/- 4 micromol x kg(-1) x min(-1): P = 0.36). Antecedent hypoglycemia local to the portal vein is required for the full induction of hypoglycemia-associated counterregulatory failure with slow-onset hypoglycemia.     

Design and synthesis of pyrimido[4,5-b][1,4]benzothiazine derivatives, as potent 15-lipoxygenase inhibitors

A group of 2-substituted pyrimido[4,5-b][1,4]benzothiazines were designed, synthesized, and evaluated as potential inhibitors of 15-lipoxygenase (15-LO). Compounds 4d and 4e showed the best IC50 of 15-LO inhibition (IC50=18 and 34 microM, respectively). All compounds were docked into 15-LO. As a result the sulfur atom was oriented toward the iron atom of the active site of 15-LO. We suggest the interaction of the iron atom is essential for the activity of the inhibitors.     

Design,synthesis and pharmacological evaluation of 6-hydroxy-4-methylquinolin-2(1H)-one derivatives as inotropic agents

Selective PDE3 inhibitors improve cardiac contractility and may be used in congestive heart failure. However, their proarrhythmic potential is the most important side effect. In this research we designed, synthesized and evaluated the potential cardiotonic activity of thirteen PDE3 inhibitors (4-[(4-methyl-2-oxo-1,2-dihydro-6-quinolinyl)oxy]butanamide analogs) using the spontaneously beating atria model. The design strategy was based on the structure of cilostamide, a selective PDE3 inhibitor. In each experiment, atrium of reserpine-treated rat was isolated and the contractile and chronotropic effects of a synthetic compounds were assessed. All experiments were carried out in comparison with IBMX, amrinone and cilostamide as standard compounds. The results showed that, among the new compounds, the best pharmacological profile was obtained with the compound 6-[4-(4-methylpiperazine-1-yl)-4-oxobutoxy]-4-methylquinolin-2(1H)-one, 4j, which displayed selectivity for increasing the force of contraction (165 ± 4% change over the control) rather than the frequency rate (115 ± 7% change over the control) at 100 μM and potent inhibitory activity of PDE3 with IC₅₀ = 0.20 μM.     

A Newton Cooperative Genetic Algorithm Method for In Silico Optimization of Metabolic Pathway Production

This paper presents an in silico optimization method of metabolic pathway production. The metabolic pathway can be represented by a mathematical model known as the generalized mass action model, which leads to a complex nonlinear equations system. The optimization process becomes difficult when steady state and the constraints of the components in the metabolic pathway are involved. To deal with this situation, this paper presents an in silico optimization method, namely the Newton Cooperative Genetic Algorithm (NCGA). The NCGA used Newton method in dealing with the metabolic pathway, and then integrated genetic algorithm and cooperative co-evolutionary algorithm. The proposed method was experimentally applied on the benchmark metabolic pathways, and the results showed that the NCGA achieved better results compared to the existing methods.     

Comparative Evaluation of Three Supplements for Helicobacter pylori Growth in Liquid Culture

Helicobacter pylori, a microaerophilic fastidious bacterium, has been cultured on various plating and broth media since its discovery. Although the agar media can be sufficient for the identification, typing, and antibiotic resistance studies, no secretory antigen of H. pylori can be evaluated in such media. Thus, satisfactory growth of H. pylori in liquid culture which is needed for analysis of secretory proteins without the presence of interfering agents is in demand. We assessed the impact of β-cyclodextrin, Fetal Bovine Serum (FBS), and charcoal as supplements for H. pylori growth. Furthermore, we aimed to identify the most favorable supplement that supports the secretion of the dominant secretory protein, vacuolating cytotoxin (VacA). Five clinical strains were cultured on broth media and the growth, viability, morphology, and protein content of each strain were determined. Our results revealed that β-cyclodextrin supports the growth rate, viability, and cell lysate protein content to the extent similar to FBS. Application of β-cyclodextrin is found to postpone spiral to coccoid conversion up to 72 h of incubation. Although FBS supports a higher VacA protein content, presence of interfering macromolecules in FBS questions its utility particularly for purposes of studying extra cellular proteins such as VacA. This study recommends further application of β-cyclodextrin as a culture supplement with the potential capacity in neutralizing toxic compounds and flourishing the secretion of H. pylori proteins without addition of interfering proteins.     

Investigation by fluorescence spectroscopy, resonance rayleigh scattering and zeta potential approaches of the separate and simultaneous binding effect of Paclitaxel and estradiol with human serum albumin

Separate and simultaneous binding effects of paclitaxel (a drug with anti-tumor activity) and estradiol (used for treating multiple maladies) with human serum albumin (HSA) were investigated by fluorescence quenching, UV absorption, circular dichroism, zeta potential and molecular dynamic techniques. An extensive fluorescence quenching was observed during the reaction of drugs and HSA and was rationalized in terms of a static quenching mechanism. The molecular distances between the donor (HSA) and acceptors (paclitaxel or estradiol) in binary and ternary systems were estimated according to F?rster's theory of dipole-dipole non-radiation energy transfer. The features of drug-induced structural disturbances of HSA have been studied in detail by synchronous fluorescence and circular dichroism (CD) analysis. The resonance Rayleigh scattering (RRS) intensities were proportional to the paclitaxel and estradiol concentrations in the range of respectively (0-8)×10(-6) and (0-1)×10(-4) mM in binary systems. The critical induced aggregation concentrations (C(CIAC)) of paclitaxel and estradiol for binary and ternary systems were determined by nonlinear relationships between the enhancement of the RRS intensities and the drug concentrations. A comparison between binary and ternary systems for two drugs allowed us to estimate the effect of a drug on the initial formation aggregation of the second drug. The zeta potential results were used to verify the existence of complexation and confirmed the C(CIAC) values obtained by the RRS technique. This phenomenon was supported by a progressive rise of the protein charge to a reversal point as a consequence of drug binding. The quantitative analysis data of circular dichroism (CD) spectra demonstrated that the binding of paclitaxel and/or estradiol to HSA induced conformational changes in HSA. Moreover, the α-helix content in HSA greatly decreased in the presence of paclitaxel as opposed when estradiol was present. Protein-ligand docking suggested that estradiol bound to residues situated in subdomain IIA of HSA. On the other hand, in the ternary system, the presence of the first drug decreased the binding affinity of the second drug to HSA. Therefore binding effects of paclitaxel and estradiol with HSA alone have different behavior than simultaneous interaction.     

An fMRI Study of Audiovisual Speech Perception Reveals Multisensory Interactions in Auditory Cortex

Research on the neural basis of speech-reading implicates a network of auditory language regions involving inferior frontal cortex, premotor cortex and sites along superior temporal cortex. In audiovisual speech studies, neural activity is consistently reported in posterior superior temporal Sulcus (pSTS) and this site has been implicated in multimodal integration. Traditionally, multisensory interactions are considered high-level processing that engages heteromodal association cortices (such as STS). Recent work, however, challenges this notion and suggests that multisensory interactions may occur in low-level unimodal sensory cortices. While previous audiovisual speech studies demonstrate that high-level multisensory interactions occur in pSTS, what remains unclear is how early in the processing hierarchy these multisensory interactions may occur. The goal of the present fMRI experiment is to investigate how visual speech can influence activity in auditory cortex above and beyond its response to auditory speech. In an audiovisual speech experiment, subjects were presented with auditory speech with and without congruent visual input. Holding the auditory stimulus constant across the experiment, we investigated how the addition of visual speech influences activity in auditory cortex. We demonstrate that congruent visual speech increases the activity in auditory cortex.     

ProDomAs,protein domain assignment algorithm using center‐based clustering and independent dominating set

Decomposition of structural domains is an essential task in classifying protein structures, predicting protein function, and many other proteomics problems. As the number of known protein structures in PDB grows exponentially, the need for accurate automatic domain decomposition methods becomes more essential. In this article, we introduce a bottom‐up algorithm for assigning protein domains using a graph theoretical approach. This algorithm is based on a center‐based clustering approach. For constructing initial clusters, members of an independent dominating set for the graph representation of a protein are considered as the centers. A distance matrix is then defined for these clusters. To obtain final domains, these clusters are merged using the compactness principle of domains and a method similar to the neighbor‐joining algorithm considering some thresholds. The thresholds are computed using a training set consisting of 50 protein chains. The algorithm is implemented using C++ language and is named ProDomAs. To assess the performance of ProDomAs, its results are compared with seven automatic methods, against five publicly available benchmarks. The results show that ProDomAs outperforms other methods applied on the mentioned benchmarks. The performance of ProDomAs is also evaluated against 6342 chains obtained from ASTRAL SCOP 1.71. ProDomAs is freely available at http://www.bioinf.cs.ipm.ir/software/prodomas . Proteins 2014; 82:1937–1946. © 2014 Wiley Periodicals, Inc.