Comparative genomic analysis of Helicobacter pylori from Malaysia identifies three distinct lineages suggestive of differential evolution

The discordant prevalence of Helicobacter pylori and its related diseases, for a long time, fostered certain enigmatic situations observed in the countries of the southern world. Variation in H. pylori infection rates and disease outcomes among different populations in multi-ethnic Malaysia provides a unique opportunity to understand dynamics of host–pathogen interaction and genome evolution. In this study, we extensively analyzed and compared genomes of 27 Malaysian H. pylori isolates and identified three major phylogeographic lineages: hspEastAsia, hpEurope and hpSouthIndia. The analysis of the virulence genes within the core genome, however, revealed a comparable pathogenic potential of the strains. In addition, we identified four genes limited to strains of East-Asian lineage. Our analyses identified a few strain-specific genes encoding restriction modification systems and outlined 311 core genes possibly under differential evolutionary constraints, among the strains representing different ethnic groups. The cagA and vacA genes also showed variations in accordance with the host genetic background of the strains. Moreover, restriction modification genes were found to be significantly enriched in East-Asian strains. An understanding of these variations in the genome content would provide significant insights into various adaptive and host modulation strategies harnessed by H. pylori to effectively persist in a host-specific manner.     

Altered Proteome of Burkholderia pseudomallei Colony Variants Induced by Exposure to Human Lung Epithelial Cells

Burkholderia pseudomallei primary diagnostic cultures demonstrate colony morphology variation associated with expression of virulence and adaptation proteins. This study aims to examine the ability of B. pseudomallei colony variants (wild type [WT] and small colony variant [SCV]) to survive and replicate intracellularly in A549 cells and to identify the alterations in the protein expression of these variants, post-exposure to the A549 cells. Intracellular survival and cytotoxicity assays were performed followed by proteomics analysis using two-dimensional gel electrophoresis. B. pseudomallei SCV survive longer than the WT. During post-exposure, among 259 and 260 protein spots of SCV and WT, respectively, 19 were differentially expressed. Among SCV post-exposure up-regulated proteins, glyceraldehyde 3-phosphate dehydrogenase, fructose-bisphosphate aldolase (CbbA) and betaine aldehyde dehydrogenase were associated with adhesion and virulence. Among the down-regulated proteins, enolase (Eno) is implicated in adhesion and virulence. Additionally, post-exposure expression profiles of both variants were compared with pre-exposure. In WT pre- vs post-exposure, 36 proteins were differentially expressed. Of the up-regulated proteins, translocator protein, Eno, nucleoside diphosphate kinase (Ndk), ferritin Dps-family DNA binding protein and peptidyl-prolyl cis-trans isomerase B were implicated in invasion and virulence. In SCV pre- vs post-exposure, 27 proteins were differentially expressed. Among the up-regulated proteins, flagellin, Eno, CbbA, Ndk and phenylacetate-coenzyme A ligase have similarly been implicated in adhesion, invasion. Protein profiles differences post-exposure provide insights into association between morphotypic and phenotypic characteristics of colony variants, strengthening the role of B. pseudomallei morphotypes in pathogenesis of melioidosis.     

The stereochemistry of N-methyl and aryl substituents determine the biological activities of 3-aryl-8-methyl-8-azabicyclo[3.2.1]oct-2,3-enes

Aryl substituted tropanes and their 2,3-ene analogs are highly selective inhibitors of monoamine uptake. The solution structures of a series of aryl tropanes were determined using NMR spectroscopy and molecular modeling to identify conformational preferences that may determine the overall activity. The majority of these analogs undergo nitrogen inversion, and the rate of interconversion between the axial and equatorial N-methyl conformers is fast on the NMR timescale at room temperature but slow between 217 and 243 K allowing us to determine the thermodynamic parameters of interconversion using dynamic and magnetization transfer NMR. The biological activities correlate strongly with the nature and the orientation of the aryl group. The relative orientation of the N-methyl further modulates the activity by directly influencing the ligand interaction in the protein binding pocket and/or by forcing a favorable orientation for the aryl substituent to fit in the binding pocket.     

Multiple sulfatase deficiency is caused by mutations in the gene encoding the human C(alpha)-formylglycine generating enzyme

C(alpha)-formylglycine (FGly) is the catalytic residue in the active site of eukaryotic sulfatases. It is posttranslationally generated from a cysteine in the endoplasmic reticulum. The genetic defect of FGly formation causes multiple sulfatase deficiency (MSD), a lysosomal storage disorder. We purified the FGly generating enzyme (FGE) and identified its gene and nine mutations in seven MSD patients. In patient fibroblasts, the activity of sulfatases is partially restored by transduction of FGE encoding cDNA, but not by cDNA carrying an MSD mutation. The gene encoding FGE is highly conserved among pro- and eukaryotes and has a paralog of unknown function in vertebrates. FGE is localized in the endoplasmic reticulum and is predicted to have a tripartite domain structure.     

Elihu Yale and the medicine he promoted: the government general hospital and Madras Medical College, India

Much has been written about the philanthropist Elihu Yale and his life in the Americas and England, where he spent his beginnings and end. Less publicized is his life in India, where he spent the majority of his adult life and where he raised his family. A major contribution of Elihu Yale to medicine in India was his promotion of a local hospital in the major Indian trading port city of Madras. This essay briefly describes the history of that hospital and the medical college that grew out of it.     

Desmoplastic Infantile Ganglioglioma: cytologic findings and differential diagnosis on aspiration material

BACKGROUND: Desmoplastic infantile ganglioglioma (DIG) is a rare WHO Grade I tumor of infancy that is characterized by large volume, superficial location, invariable supratentoriality, fronto-parietal lobe predilection and morphologically, by an admixture of astroglial and neuroepithelial elements in a desmoplastic milieu. With over 50 cases described, the histologic and radiographic spectrum of DIG has been well-characterized. The superficial location of DIGs may render them greatly amenable to preoperative assessment utilizing aspiration cytology; however, the cytologic features of this rare tumor have only been reported once previously. CASE PRESENTATION: We present herein cytomorphologic findings from the intraoperative aspiration of a typical case of DIG diagnosed in a 1-year-old male. As evaluated on a single liquid-based preparation, the specimen showed low cellularity and was comprised predominantly of a population of dispersed (occasionally clustered) large neuronal cells with eccentrically located hyperchromatic nuclei (which were occasionally binucleated) and abundant unipolar cytoplasm. Rare smaller astroglial cells were intermixed. Despite the tumor's characteristic desmoplastic histologic appearance, no stromal fragments were identified on the aspiration material. CONCLUSIONS: A differential diagnosis is presented and analyzed in detail and it is concluded that when these large neuronal cells are encountered in an aspirate of a brain mass in a child, a combination of clinical, radiologic and immunohistochemical parameters can eliminate most of the differential possibilities.     

Phospholipase Cgamma-Erk Axis in vascular endothelial growth factor-induced eukaryotic initiation factor 4E phosphorylation and protein synthesis in renal epithelial cells

Vascular endothelial growth factor (VEGF) increases protein synthesis and induces hypertrophy in renal tubular epithelial cells (Senthil, D., Choudhury, G. G., McLaurin, C., and Kasinath, B. S. (2003) Kidney Int. 64, 468-479). We examined the role of Erk1/2 MAP kinase in protein synthesis induced by VEGF. VEGF stimulated Erk phosphorylation that was required for induction of protein synthesis. VEGF-induced Erk activation was not dependent on phosphoinositide (PI) 3-kinase activation but required sequential phosphorylation of type 2 VEGF receptor, PLCgamma and c-Src, as demonstrated by inhibitors SU1498, U73122, and PP1, respectively. c-Src phosphorylation was inhibited by U73122, indicating it was downstream of phospholipase (PL)Cgamma. Studies with PP1/2 showed that phosphorylation of c-Src was required for tyrosine phosphorylation of Raf-1, an upstream regulator of Erk. VEGF also stimulated phosphorylation of Pyk-2; VEGF-induced phosphorylation of Pyk2, c-Src and Raf-1 could be abolished by BAPTA/AM, demonstrating requirement for induction of intracellular calcium currents. We examined the downstream events following the phosphorylation of Erk. VEGF stimulated phosphorylation of Mnk1 and eIF4E and induced Mnk1 to shift from the cytoplasm to the nucleus upon phosphorylation. VEGF-induced phosphorylation of Mnk1 and eIF4E required phosphorylation of PLCgamma, c-Src, and Erk. Expression of dominant negative Mnk1 abrogated eIF4E phosphorylation and protein synthesis induced by VEGF. VEGF-stimulated protein synthesis could be blocked by inhibition of PLCgamma by a chemical inhibitor or expression of a dominant negative construct. Our data demonstrate that VEGF-stimulated protein synthesis is Erk-dependent and requires the activation of VEGF receptor 2, PLCgamma, c-Src, Raf, and Erk pathway. VEGF also stimulates Erk-dependent phosphorylation of Mnk1 and eIF4E, crucial events in the initiation phase of protein translation.     

Expression, localization, structural, and functional characterization of pFGE, the paralog of the Calpha-formylglycine-generating enzyme

pFGE is the paralog of the formylglycine-generating enzyme (FGE), which catalyzes the oxidation of a specific cysteine to Calpha-formylglycine, the catalytic residue in the active site of sulfatases. The enzymatic activity of sulfatases depends on this posttranslational modification, and the genetic defect of FGE causes multiple sulfatase deficiency. The structural and functional properties of pFGE were analyzed. The comparison with FGE demonstrates that both share a tissue-specific expression pattern and the localization in the lumen of the endoplasmic reticulum. Both are retained in the endoplasmic reticulum by a saturable mechanism. Limited proteolytic cleavage at similar sites indicates that both also share a similar three-dimensional structure. pFGE, however, is lacking the formylglycine-generating activity of FGE. Although overexpression of FGE stimulates the generation of catalytically active sulfatases, overexpression of pFGE has an inhibitory effect. In vitro pFGE interacts with sulfatase-derived peptides but not with FGE. The inhibitory effect of pFGE on the generation of active sulfatases may therefore be caused by a competition of pFGE and FGE for newly synthesized sulfatase polypeptides.