Insight to pyrazinamide resistance inMycobacterium tuberculosisby molecular docking

Pyrazinamide (PZA) - an important drug in the anti-tuberculosis therapy, activated by an enzyme Pyrazinamidase (PZase). The basis of PZA resistance in Mycobacterium tuberculosis was owing to mutation in pncA gene coding for PZase. Homology modeling of PZase was performed using software Discovery Studio (DS) 2.0 based on the crystal structure of the PZase from Pyrococcus horikoshii (PDB code 1im5), in this study. The model comprises of one sheet with six parallel strands and seven helices with the amino acids Asp8, Asp49, Trp68, Lys96, Ala134, Thr135 and Cys138 at the active site. Five mutants were generated with Gly at position 8, Thr at position 96, Arg at position 104, Tyr and Ser at position 138. The Wild-type (WT) and five mutant models were docked with PZA. The results indicate that the mutants Lys96Thr, Ser104Arg Asp8Gly and Cys138Tyr may contribute to higher level drug resistance than Cys138Ser. These models provide the first in-silico evidence for the binding interaction of PZA with PZase and form the basis for rationalization of PZA resistance in naturally occurring pncA mutant strains of M. tuberculosis.     

Dermatoglyphic changes during the population admixture between Kam and Han Chinese

Genetic studies and gene localization for human dermatoglyphs are currently ongoing. However, the inheritance modes of various genetic traits are not well understood because of the complexity of dermatoglyph genetics. The study of admixed populations can contribute to the understanding of population genetic traits of dermatoglyphs. Here, we present the dermatoglyphic characteristics of Kam and Liujia Han, and the admixed population consisting of these two parent populations.The characteristics of the admixed population do not always fall in the same ranges as the parent population characters but do seem to be biased to Kam or Liujia parent populations, depending on sex and ethnicity of parents. The total frequencies of different fingerprint types do not differ among these populations, but several of the quantitative traits and the palm true pattern frequencies do significantly differ between admixed and parent populations. The simple arch fingerprint frequency decreases significantly in the admixed population in comparison with parent populations while both simple whorl fingerprint frequency and finger ridge counts increase significantly. True pattern frequency of the span area of interdigital III and IV areas on right hands and the radial-loop frequency of the right index fingers in the admixed populations are consistent with their matrilineal population. These dermatoglyphic changes may result from increased heterozygosity in the admixed population. The genetic modes of these changes may be relatively simple and will be useful for future dermatoglyph genetic studies.      

Negative modulation of eNOS by laminin involving post‐translational phosphorylation

Nitric oxide (NO) regulates the vascular tone, and influences survival and apoptosis of endothelial cells (ECs). NO is produced by nitric oxide synthase (NOS) and eNOS is the constitutive enzyme in the endothelium. Though the extracellular matrix (ECM) has been reported to regulate various EC functions, the role of ECM in the regulation of eNOS is not clear. The present study was designed to analyze if laminin‐1 (Ln‐1), the major glycoprotein of the basement membrane, can regulate eNOS. The activity of eNOS was significantly low in ECs maintained on Ln‐1 as compared to those on Col I and polylysine. Reversal of the effect of Ln‐1 on treatment with inhibitor of p38 MAPK and changes in Thr and Ser phosphorylation in purified eNOS suggested that eNOS activity in cells maintained on Ln‐1 is negatively regulated by post‐translational phosphorylation at Ser and Thr residues by recruiting p38 MAPK pathway. Increase in eNOS activity and induction of apoptosis upon inhibition of p38 MAPK and reversal of this on inhibition of NOS by L ‐NAME suggested that increased NO induced apoptosis in ECs maintained on Ln‐1 when p38 MAPK was inhibited. These results suggest that Ln contributes to survival of ECs by negatively modulating eNOS in a p38 MAPK dependent pathway. J. Cell. Physiol. 219: 123–131, 2009. © 2008 Wiley‐Liss, Inc.     

Straightforward and complete deposition of NMR data to the PDBe

We present a suite of software for the complete and easy deposition of NMR data to the PDB and BMRB. This suite uses the CCPN framework and introduces a freely downloadable, graphical desktop application called CcpNmr Entry Completion Interface (ECI) for the secure editing of experimental information and associated datasets through the lifetime of an NMR project. CCPN projects can be created within the CcpNmr Analysis software or by importing existing NMR data files using the CcpNmr FormatConverter. After further data entry and checking with the ECI, the project can then be rapidly deposited to the PDBe using AutoDep, or exported as a complete deposition NMR-STAR file. In full CCPN projects created with ECI, it is straightforward to select chemical shift lists, restraint data sets, structural ensembles and all relevant associated experimental collection details, which all are or will become mandatory when depositing to the PDB. Instructions and download information for the ECI are available from the PDBe web site at http://www.ebi.ac.uk/pdbe/nmr/deposition/eci.html.     

A novel achiral seco-cyclopropylpyrido[e]indolone (CPyI) analog of CC-1065 and the duocarmycins: Synthesis,DNA interactions,in vivo anticancer and anti-parasitic evaluation

The synthesis of an achiral seco-hydroxy-aza-CBI-TMI analog (8) of the duocarmycins is reported. Its specificity for the DNA minor groove of AT-rich sequences and covalent bonding to adenine-N3 was ascertained by a thermal cleavage assay. Compound 8 was found to be cytotoxic in the nanomolar range against murine and human cancer cells. It was further demonstrated that compound 8 was active against murine melanoma (B16-F0) grown in C57BL/6 mice. Compound 8 was also shown to inhibit the growth of the protozoan parasites Leishmania donovani, Leishmania mexicana, Trypanosoma brucei, and Plasmodium falciparum in culture.     

Response Surface Methodology to Optimize Novel Fast Disintegrating Tablets Using β Cyclodextrin as Diluent

The objective of this work was to apply response surface approach to investigate main and interaction effects of formulation parameters in optimizing novel fast disintegrating tablet formulation using β cyclodextrin as a diluent. The variables studied were diluent (β cyclodextrin, X ₁), superdisintegrant (Croscarmellose sodium, X ₂), and direct compression aid (Spray dried lactose, X ₃). Tablets were prepared by direct compression method on B2 rotary tablet press using flat plain-face punches and characterized for weight variation, thickness, disintegration time (Y ₁), and hardness (Y ₂). Disintegration time was strongly affected by quadratic terms of β cyclodextrin, croscarmellose sodium, and spray-dried lactose. The positive value of regression coefficient for β cyclodextrin suggested that hardness increased with increased amount of β cyclodextrin. In general, disintegration of tablets has been reported to slow down with increase in hardness. However in the present study, higher concentration of β cyclodextrin was found to improve tablet hardness without increasing the disintegration time. Thus, β cyclodextrin is proposed as a suitable diluent to achieve fast disintegrating tablets with sufficient hardness. Good correlation between the predicted values and experimental data of the optimized formulation validated prognostic ability of response surface methodology in optimizing fast disintegrating tablets using β cyclodextrin as a diluent.     

Ultrasonographic soft markers of aneuploidy in second trimester: are we lost?

Chromosomal abnormalities occur in 0.1% to 0.2% of live births, and the most common clinically significant aneuploidy among live-born infants is Down syndrome (trisomy 21). Other sonographically detectable aneuploidies include trisomy 13, 18, monosomy X, and triploidy. Second-trimester ultrasound scan detects 2 types of sonographic markers suggestive of aneuploidy. Markers for major fetal structural abnormalities comprise the first type; the second type of markers are known as "soft markers" of aneuploidy. These latter markers are nonspecific, often transient, and can be readily detected during the second-trimester ultrasound. The most commonly studied soft markers of aneuploidy include a thickened nuchal fold, rhizomelic limb shortening, mild fetal pyelectasis, echogenic bowel, and echogenic intracardiac focus and choroid plexus cyst. There is a great deal of interest in the ultrasound detection of aneuploidy, as evidenced by the large number of publications in the literature on this topic. Unfortunately, studies evaluating the significance of the soft markers of aneuploidy vary widely and show contradictory results. In this article, we review the most common ultrasonographic soft markers used to screen aneuploidy and discuss ultrasonographic technique and measurement criteria for the detection of soft markers. We also review the clinical relevance of soft markers to aneuploidy risk assessment and evidence-based strategies for the management of affected pregnancies with each of these markers in light of current literature.     

Ca2+ activation of the cPLA2 C2 domain: ordered binding of two Ca2+ ions with positive cooperativity

During Ca(2+) activation, the Ca(2+)-binding sites of C2 domains typically bind multiple Ca(2+) ions in close proximity. These binding events exhibit positive cooperativity, despite the strong charge repulsion between the adjacent divalent cations. Using both experimental and computational approaches, the present study probes the detailed mechanisms of Ca(2+) activation and positive cooperativity for the C2 domain of cytosolic phospholipase A(2), which binds two Ca(2+) ions in sites I and II, separated by only 4.1 A. First, each of the five coordinating side chains in the Ca(2+)-binding cleft is individually mutated and the effect on Ca(2+)-binding affinity and cooperativity is measured. The results identify Asp 43 as the major contributor to Ca(2+) affinity, while the two coordinating side chains that provide bridging coordination to both Ca(2+) ions, Asp 43 and Asp 40, are observed to make the largest contributions to positive cooperativity. Electrostatic calculations reveal that Asp 43 possesses the highest pseudo-pK(a) of the coordinating acidic residues, as well as the highest general cation affinity, due to its relatively buried location within 3.5 A of seven protein oxygens with full or partial negative charges. These calculations therefore explain the greater importance of Asp 43 in defining the Ca(2+) affinity. Overall, the experimental and computational results support an activation model in which the first Ca(2+) ion binds usually to site I, thereby preordering both bridging side chains Asp 40 and 43, and partially or fully deprotonating the three coordinating Asp residues. This initial binding event prepares the conformation and protonation state of the remaining site for Ca(2+) binding, enabling the second Ca(2+) ion to bind with higher affinity than the first as required for positive cooperativity.