Maturation dynamics of bacteriophage HK97 capsid

Maturation of the bacteriophage HK97 capsid requires a large conformational change of the virus capsid. Experimental studies have identified several intermediates along this maturation pathway. To gain insights into the molecular mechanisms of capsid maturation, we examined the fluctuation dynamics of the procapsid and mature capsid using a residue-level computational approach. The most cooperative motions of the procapsid are found to be consistent with the observed change in configuration that takes place during maturation. A few dominant modes of motion are sufficient to describe the anisotropic expansion that accompanies maturation. Based upon these modes, maturation is proposed to occur via an overall expansion and reconfiguration of the capsid initiated by puckering of the pentamers, followed by flattening and crosslinking of the hexameric subunits, and finally crosslinking of the pentameric subunits. The highly mobile E loops are stabilized by anchoring to highly stable residues belonging to neighboring subunits.     

Computational design of Phe-Tyr dipeptide and preparation,characterization, cytotoxicity studies of Phe-Tyr dipeptide loaded PLGA nanoparticles for the treatment of hypertension

Phe-Tyr dipeptide which was investigated in Wakame food with greatest ACE-inhibitory activity is used as a pharmaceutical drug for the treatment of hypertension, cardiovascular diseases, and diabetic nephropathy. To improve the bioavailability of Phe-Tyr, a delivery system based on poly (lactic-co-glycolic acid) (PLGA) nanoparticles loaded with Phe-Tyr (Phe-Tyr-PLGA NPs) for treating hypertension and cardiovascular diseases was prepared in this study. In the experiments, poly(lactic-co-glycolic acid) (PLGA) and Phe-Tyr dipeptide-loaded PLGA nanoparticles were prepared using the double emulsion (w/o/w) method. The characterizations of the nanoparticles were performed with a UV–vis spectrometer, the Zeta-sizer system, and FTIR spectrometer. The optimum size of the Phe-Tyr dipeptide-loaded PLGA nanoparticle was obtained with a 213.8 nm average particle size, and a 0.061 polydispersity index, ?19.5 mV zeta potential, 34% of loaded and 90.09% of encapsulation efficiency. From TEM analysis, it was clearly seen that the dipeptide loaded nanoparticles had the spherical and non-aggregated morphology and Phe-Tyr dipeptide loaded-PLGA nanoparticles were obtained successfully. Cell toxicity of nanoparticles at different concentrations was assayed with XTT methods on L929 fibroblast cells. This study determined that the nanoparticles have low toxicity at lower concentration and toxicity augmented with increasing concentration of dipeptide. To analyze the effect of solvents on structure of Phe-Tyr, Molecular dynamics simulation was performed with GROMACS program and molecular orbital calculations were carried out to obtain structural and electronic properties of dipeptide. Moreover, molecular docking calculations were also employed to model and predict protein–drug interactions.     

Hyperhidrosis Prevalence and Demographical Characteristics in Dermatology Outpatients in Shanghai and Vancouver

BackgroundThere is a wide variation in the reported prevalence of primary hyperhidrosis in the literature. Further, it is unknown if primary hyperhidrosis is a lifelong condition, or if demographical factors influence hyperhidrosis prevalence.ObjectivesThis study aims to examine the prevalence of hyperhidrosis in multiple ethnic groups from two ethnically diverse cities and to determine if the prevalence of primary hyperhidrosis changes according to age, gender, ethnicity, body mass index, and geographical locations.MethodsIn total, 1010 consecutive subjects attending dermatology outpatient clinics in Shanghai Skin Disease Hospital and 1018 subjects in Skin Care Center of Vancouver General Hospital were invited to fill out a questionnaire on their presenting concerns, demographical information, and sweating symptoms. The subjects were then classified to have primary hyperhidrosis using the criteria of International Hyperhidrosis Society, late-onset hyperhidrosis, or no-hyperhidrosis. The prevalence of primary HH and late-onset HH was calculated for the entire study population and in subgroups stratified according to age of examination, sex, ethnicity, presenting diagnosis, body mass index, and specific study cities. Multivariate logistic regression analyses were performed to assess the impact of these factors on HH prevalence.ResultsThe prevalence of primary hyperhidrosis is very similar in Shanghai and in Vancouver, at 14.5% and 12.3% respectively. In addition, 4.0% of subjects in Shanghai and 4.4% subjects in Vancouver suffer from late-onset HH. Primary HH has highest prevalence in those younger than 30 years of age, decreasing dramatically in later years. Caucasian subjects are at least 2.5 times more likely to develop axillary hyperhidrosis compared to Chinese subjects. Obesity does not have much influence on primary HH presentation, although it does increase significantly the development of late-onset HH. Finally, there is no major difference of hyperhidrosis between Chinese subjects in Shanghai and Vancouver.LimitationsThe data were gathered according to patients’ self-reports only and the sample size was relatively small in some groups after stratification for gender, ethnicity and age.ConclusionPrevalence of primary HH and late-onset HH is similar in dermatology outpatients independent of geographical locations. However, certain specific HH subtypes can show great variations according to ethnicity, age, body mass index and sex.     

Analysis of Methanogenic Archaeal and Sulphate Reducing Bacterial Populations in Deep Sediments of the Black Sea

In this study, the distribution, morphology and relative abundance of Sulfate Reducing Bacterial (SRB) and Methanogenic Archaeal (MA) populations in the Black Sea sediments were investigated by using in situ hybridization with fluorescently labeled rRNA-targeted oligonucleotide probes. Results were discussed with respect to the characteristics of sampling points. MA and SRB showed a great diversity in all sediment samples. Higher abundance of MA (20–30%) and SRB (30–35%) populations were observed within the sediments from deeper parts of the Black Sea than the shallower parts (10–11% MA and 13–14% SRB). Desulfobotulus, Desulfosarcina and Desulfococcus groups were the most commonly detected SRB groups in the Black Sea sediments. Relative percentage of these SRB groups within sediments from deeper parts of the Black Sea was in a range of 17–21% whereas that of was in a range of 4–5% within the sediments from the shallower parts. Order Methanococcales were the dominant methanogenic group in all samples. Relative percentages of order Methanococcales were in a range of 8–12% and 4–5% within sediments from deeper parts and the coastal parts of the Black Sea, respectively.     

Detection and identification of optical activity using polarimetry – applications to biophotonics,biomedicine and biochemistry

Polarized light that is reflected or transmitted through chiral specimens can be used to detect and identify biological and chemical materials including human tissue. The determination of the silent footprints of the chiral properties of the biological materials on scattered polarized light is the basis for these investigations. It is of primary importance to identify which combinations of the elements of the Mueller matrix for reflected or for transmitted light can be used to determine the optical activity of the biochemical materials. The optical activity of chiral materials is characterized by optical rotation and circular dichroism. The explicit analytical dependence of these specific elements of the Mueller matrix, upon the angles of incidence and scatter, upon the wavelength and upon the type of chirality has the potential to provide experimentalists with guidance in determining the optimum use of optical polarimetric scatterometers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Inhibition by nitric oxide of cytochrome P450 4A activity contributes to endotoxin-induced hypotension in rats.

Nitric oxide (NO) production during endotoxemia is associated with decreased total CYP content, CYP 1A1/2, 2B1/2, 2C6, 2C11, 3A1, and 3A2 mRNA, protein expression or activity which is prevented by NO synthase (NOS) inhibitors in rats. This study was conducted to determine if endotoxin-induced hypotension caused by NO production is mediated by inhibition of renal CYP 4A protein expression and activity. In conscious male Sprague-Dawley rats, endotoxin (10 mg/kg, ip) reduced mean arterial pressure (MAP), increased serum and renal nitrite levels, and inducible NOS (iNOS), and decreased renal CYP 4A1/A3 protein and CYP 4A activity. The selective iNOS inhibitor 1,3-PBIT (10 mg/kg, ip; 1h after endotoxin) prevented endotoxin-induced decrease in MAP, renal CYP 4A1/A3 protein level and CYP 4A activity and increase in systemic and renal nitrite production. The selective constitutive NOS (cNOS) inhibitor N(G)-nitro-L-arginine (L-NNA; 20 mg/kg, ip; 1 h after endotoxin) partially attenuated endotoxin-induced decrease in MAP. The selective CYP 4A inhibitor, aminobenzotriazole (50 mg/kg, ip; 1 h after endotoxin) diminished CYP 4A1/A3 protein level and CYP 4A activity. Aminobenzotriazole did not alter the endotoxin-induced decrease in MAP, but it reversed the effect of 1,3-PBIT in preventing endotoxin-induced fall in MAP and CYP 4A activity. These data suggest that the endotoxemia-induced increase in NO production primarily via iNOS suppresses renal CYP 4A expression and activity, and inhibition of iNOS with 1,3-PBIT restores renal CYP 4A protein and activity and MAP presumably due to increased production of arachidonic acid metabolites derived from CYP 4A.     

High level synthesis of levan by a novel Halomonas species growing on defined media

A novel halophilic isolate from soil samples taken from Çamalt? Saltern area in Turkey, Halomonas sp. AAD6 (JCM 15723) strain, was found to produce high levels of exopolysaccharides (EPS), in the presence of sucrose in defined media, by flasks and bioreactor condition yielded 1.073 g L^?1 and 1.844 g L^?1, respectively. Sugar analysis, methylation studies and NMR analysis of EPS indicated the repeating unit of this polysaccharide was composed of β-(2,6)-d-fructofuranosyl residues. Hence with this work, Halomonas sp. has been described as a levan producer microorganism for the first time. Biocompatibility studies showed this EPS did not affect cellular viability and proliferation of osteoblasts and murine macrophages. The protective effect of the polymer against the toxic activity of avarol implied its additional use as an anti-cytotoxic agent. Halomonas sp. AAD6 could represent an alternative cheap source of levan polymer when grown on defined media hypothesizing its larger employment in industrial application being non pathogenic microorganism.     

Common mechanism of pore opening shared by five different potassium channels

A fundamental question associated with the function of ion channels is the conformational changes that allow for reversibly opening/occluding the pore through which the cations permeate. The recently elucidated crystal structures of potassium channels reveal similar structural motifs at their pore-forming regions, suggesting that they share a common gating mechanism. The validity of this hypothesis is explored by analyzing the collective dynamics of five known K(+) channel structures. Normal-mode analysis using the Gaussian network model strikingly reveals that all five structures display the same intrinsic motions at their pore-forming region despite the differences in their sequences, structures, and activation mechanisms. Superposition of the most cooperative mode profiles shows that the identified common mechanism is a global corkscrew-like counterrotation of the extracellular and cytoplasmic (CP) regions, leading to the opening of the CP end of the pore. A second cooperative mode shared by all five K(+) channels is the extension of the extracellular and/or CP ends via alternating anticorrelated fluctuations of pairs of diagonally opposite monomers. Residues acting as hinges/anchors in both modes are highly conserved across the members of the family of K(+) channel proteins, consistent with their presently disclosed critical mechanical role in pore gating.