Both Subcutaneous and Visceral Adipose Tissue Correlate Highly with Insulin Resistance in African Americans

Objective: The contribution of visceral adipose tissue (VAT) to insulin resistance is well‐established; however, the role of subcutaneous abdominal adipose tissue (SAT) in insulin resistance remains controversial. Sex may determine which of these two components of abdominal obesity is more strongly related to insulin resistance and its consequences. The aim of this study was to determine whether both VAT and SAT contribute to insulin resistance in African Americans and to examine the effects of sex on this relationship. Research Methods and Procedures: This was a cross‐sectional study of 78 nondiabetic African‐American volunteers (44 men, 35 women; age 33.8 ± 7.3 years; BMI 30.9 ± 7.4 kg/m²). VAT and SAT volumes were measured using serial computerized tomography slices from the dome of the diaphragm to the iliac crest. The insulin sensitivity index (S_I) was determined from the minimal model using data obtained from the frequently sampled intravenous glucose tolerance test. Results: In men, both VAT and SAT were negatively correlated with S_I (r for both correlations = ?0.57; p < 0.01). In women, the correlation coefficient between VAT and S_I was ?0.50 (p < 0.01) and between SAT and S_I was ?0.67 (p < 0.01). In women, the correlation coefficient for S_I with SAT was significantly greater than the correlation coefficient with VAT (p = 0.02). Discussion: Both SAT and VAT are strongly correlated with insulin resistance in African Americans. For African‐American women, SAT may have a greater effect than VAT on insulin resistance.     

Design, synthesis, and biological evaluation of 1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl pyrazolines as cyclooxygenase-2 (COX-2) and lipoxygenase (LOX) inhibitors

A series of 20 novel 1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl pyrazolines were designed, synthesized, and screened in vitro for anti-inflammatory activity. These compounds were designed for evaluation as dual inhibitors of cyclooxygenases (COX-1 and COX-2) and lipoxygenases (LOX-5, LOX-12, and LOX-15) that are responsible for inflammation and pain. All pyrazoline molecules prepared are optically active and compounds that are more potent in COX-2 inhibitory activity (5a and 5f) were resolved by chiral column and each enantiomer was tested for cyclooxygenase inhibitory activity. Molecular modeling and comparison of molecular models of 5a enantiomers with that of celecoxib model shows that 5a (enantiomer-1) and 5a (enantiomer-2) have more hydrogen bonding interactions in the catalytic domain of COX-2 enzyme than celecoxib. Compounds 5a, 5e, and 5f showed moderate to good LOX-5 and LOX-15 inhibitory activity and this is comparable to that of celecoxib and more potent than rofecoxib.     

ACUTE EFFECTS OF A RESISTED DYNAMIC WARM-UP PROTOCOL ON JUMPING PERFORMANCE

This study aimed to investigate the kinematic and kinetic changes when resistance is applied in horizontal and vertical directions, produced by using different percentages of body weight, caused by jumping movements during a dynamic warm-up. The group of subjects consisted of 35 voluntary male athletes (19 basketball and 16 volleyball players; age: 23.4 ± 1.4 years, training experience: 9.6 ± 2.7 years; height: 177.2 ± 5.7 cm, body weight: 69.9 ± 6.9 kg) studying Physical Education, who had a jump training background and who were training for 2 hours, on 4 days in a week. A dynamic warm-up protocol containing seven specific resistance movements with specific resistance corresponding to different percentages of body weight (2%, 4%, 6%, 8%, 10%) was applied randomly on non consecutive days. Effects of different warm-up protocols were assessed by pre-/post- exercise changes in jump height in the countermovement jump (CMJ) and the squat jump (SJ) measured using a force platform and changes in hip and knee joint angles at the end of the eccentric phase measured using a video camera. A significant increase in jump height was observed in the dynamic resistance warm-up conducted with different percentages of body weight (p < 0.05). On the other hand, no significant difference in different percentages of body weight states was observed (p > 0.05). In jump movements before and after the warm-up, while no significant difference between the vertical ground reaction forces applied by athletes was observed (p > 0.05), in some cases of resistance, a significant reduction was observed in hip and knee joint angles (p < 0.05). The dynamic resistance warm-up method was found to cause changes in the kinematics of jumping movements, as well as an increase in jump height values. As a result, dynamic warm-up exercises could be applicable in cases of resistance corresponding to 6-10% of body weight applied in horizontal and vertical directions in order to increase the jump performance acutely.     

Design and synthesis of functionalized piperazin-1yl-(E)-stilbenes as inhibitors of 17α-hydroxylase-C17,20-lyase (Cyp17)

The synthesis of steroid hormones is critical to human physiology and improper regulation of either the synthesis of these key molecules or activation of the associated receptors can lead to disease states. This has led to intense interest in developing compounds capable of modulating the synthesis of steroid hormones. Compounds capable of inhibiting Cyp19 (Aromatase), a key enzyme in the synthesis of estrogens, have been successfully employed as breast cancer therapies, while inhibitors of Cyp17 (17α-hydroxylase-17,20-lyase), a key enzyme in the synthesis of glucocorticoids, mineralocorticoids and steroidal sex hormones, are a key component of prostate cancer therapy. Inhibition of CYP17 has also been suggested as a possible target for the treatment of Cushing Syndrome and Metabolic Syndrome. We have identified two novel series of stilbene based CYP17 inhibitors and demonstrated that exemplary compounds in these series have pharmacokinetic properties consistent with orally delivered drugs. These findings suggest that compounds in these classes may be useful for the treatment of diseases and conditions associated with improper regulation of glucocorticoids synthesis and glucocorticoids receptor activation.     

Four structural subclasses of the antivirulence drug target disulfide oxidoreductase DsbA provide a platform for design of subclass-specific inhibitors

By catalyzing oxidative protein folding, the bacterial disulfide bond protein A (DsbA) plays an essential role in the assembly of many virulence factors. Predictably, DsbA disruption affects multiple downstream effector molecules, resulting in pleiotropic effects on the virulence of important human pathogens. These findings mark DsbA as a master regulator of virulence, and identify the enzyme as a target for a new class of antivirulence agents that disarm pathogenic bacteria rather than killing them. The purpose of this article is to discuss and expand upon recent findings on DsbA and to provide additional novel insights into the druggability of this important disulfide oxidoreductase by comparing the structures and properties of 13 well-characterized DsbA enzymes. Our structural analysis involved comparison of the overall fold, the surface properties, the conformations of three loops contributing to the binding surface and the sequence identity of residues contributing to these loops. Two distinct structural classes were identified, classes I and II, which are differentiated by their central β-sheet arrangements and which roughly separate the DsbAs produced by Gram-negative from Gram-positive organisms. The classes can be further subdivided into a total of four subclasses on the basis of surface features. Class Ia is equivalent to the Enterobacteriaceae class that has been defined previously. Bioinformatic analyses support the classification of DsbAs into 3 of the 4 subclasses, but did not pick up the 4th subclass which is only apparent from analysis of DsbA electrostatic surface properties. In the context of inhibitor development, the discrete structural subclasses provide a platform for developing DsbA inhibitory scaffolds with a subclass-wide spectrum of activity. We expect that more DsbA classes are likely to be identified, as enzymes from other pathogens are explored, and we highlight the issues associated with structure-based inhibitor development targeting this pivotal mediator of bacterial virulence. This article is part of a Special Issue entitled: Thiol-Based Redox Processes.     

Mutation at I-A beta chain prevents experimental autoimmune myasthenia gravis

Immune response (Ir) gene(s) at the I-A subregion of the mouse H-2 complex influence susceptibility to experimental autoimmune myasthenia gravis (EAMG). To determine the importance of the Ir gene product, the Ia antigens, in EAMG pathogenesis, we studied the degree of EAMG susceptibility of an I-A mutant strain, the B6.C-H-2 ^bm12 (bm12), and its parent B6/Kh. According to the cellular, humoral, biochemical, and clinical manifestations of EAMG, the I-A mutation converted an EAMG susceptible strain (B6/Kh) into a relatively resistant strain (bm12). The relative resistance to EAMG induction in bm12 may be due to the lack of Ia.8 and/or la.39 determinants and/or quantitative expression of la antigens.Abbreviations used in this paper MG myasthenia gravis - AChR acetylcholine receptors - EAMG experimental autoimmune myasthenia gravis - Ir immune response - B6 C57BL/6J - bm12 B6.C-H-2 ^bm12 - CFA complete Freund's adjuvant - LNC lymph node cells - PPD purified protein derivative     

Muscarinic acetylcholine receptor produced in recombinant baculovirus infected Sf9 insect cells couples with endogenous G-proteins to activate ion channels.

Following the infection of insect ovarian cells (Sf9) with recombinant bearing the cDNA coding for the rat muscarinic acetylcholine (ACh) receptor subtype m3, ionic flux across the membrane in response to the application of ACh was examined electrophysiologically. We show that ACh activates potassium currents. The response is abolished when cells are treated with pertussis toxin. No ACh-induced currents are observed from uninfected cells or cells infected with virus which do not contain the cDNA coding for ACh receptors in its genome. The characteristics of single channel currents show time-dependent changes following the application of ACh. Initially, ACh activates brief channel currents with a conductance of about 5 pS. The conductance level of channels gradually increases in steps to 10 pS and then to 20 pS and 40 pS. At the same time, channel open probability also increases. Thereafter, additional channels appear, opening and closing independently of, or at times in synchrony with, the original channel.     

Stoichiometry of Recombinant N-Methyl-d-Aspartate Receptor Channels Inferred from Single-channel Current Patterns

Single-channel currents were recorded from mouse NR1-NR2B (ζ-ε₂) receptors containing mixtures of wild-type and mutant subunits expressed in Xenopus oocytes. Mutant subunits had an asparagine-to-glutamine (N-to-Q) mutation at the N₀ site of the M2 segment (NR1:598, NR2B:589). Receptors with pure N or Q NR1 and NR2 subunits generated single-channel currents with distinctive current patterns. Based on main and sublevel amplitudes, occupancy probabilities, and lifetimes, four patterns of current were identified, corresponding to receptors with the following subunit compositions (NR1/NR2): N/N, N/Q, Q/N, and Q/Q. Only one current pattern was apparent for each composition. When a mixture of N and Q NR2 subunits was coexpressed with pure mutant NR1 subunits, three single-channel current patterns were apparent. One pattern was the same as Q/Q receptors and another was the same as Q/N receptors. The third, novel pattern presumably arose from hybrid receptors having both N and Q NR2 subunits. When a mixture of N and Q NR1 subunits was coexpressed with pure mutant NR2 subunits, six single-channel current patterns were apparent. One pattern was the same as Q/Q receptors and another was the same as N/Q receptors. The four novel patterns presumably arose from hybrid receptors having both N and Q NR1 subunits. The relative frequency of NR1 hybrid receptor current patterns depended on the relative amounts of Q and N subunits that were injected into the oocytes. The number of hybrid receptor patterns suggests that there are two NR2 subunits per receptor and is consistent with either three or five NR1 subunits per receptor, depending on whether or not the order of mutant and wild-type subunits influences the current pattern. When considered in relation to other studies, the most straightforward interpretation of the results is that N-methyl-d-aspartate receptors are pentamers composed of three NR1 and two NR2 subunits.     

Subconductance States of a Mutant NMDA Receptor Channel Kinetics,Calcium, and Voltage Dependence

The kinetic properties of main and subconductance states of a mutant mouse N-methyl-d-aspartate (NMDA) receptor channel were examined. Recombinant receptors made of ζ-ε₂ (NR1-NR2B) subunits having asparagine-to-glutamine mutations in the M2 segment (ζN598Q /ε₂N589Q) were expressed in Xenopus oocytes. Single channel currents recorded from outside-out patches were analyzed using hidden Markov model techniques. In Ca²⁺-free solutions, an open receptor channel occupies a main conductance (93 pS) and a subconductance (62 pS) with about equal probability. There are both brief and long-lived subconductance states, but only a single main level state. At −80 mV, the lifetime of the main and the longer-lived sub level are both ∼3.3 ms. The gating of the pore and the transition between conductance levels are essentially independent processes. Surprisingly, hyperpolarization speeds both the sub-to-main and main-to-sub transition rate constants (∼120 mV/e-fold change), but does not alter the equilibrium occupancies. Extracellular Ca²⁺ does not influence the transition rate constants. We conclude that the subconductance levels arise from fluctuations in the energetics of ion permeation through a single pore, and that the voltage dependence of these fluctuations reflects the modulation by the membrane potential of the barrier between the main and subconductance conformations of the pore.