Modulation of quorum sensing controlled behaviour of bacteria by growing seedling,seed and seedling extracts of leguminous plants

Effect of growing seedling, seeds and seedlings extracts from seven leguminous plants (Pisum sativum, Vigna radiata, Vigna mungo, Cajanus cajan, Lentil culinaris, Cicer arietinum and Trigonella foenum graecum) were screened for their ability to influence quorum sensing controlled pigment production in Chromobacterium violaceum indicator strains (CV12472 and CVO26). Germinating seedling and seedling extracts of only P. sativum (pea) showed inhibition of violacein production. Interestingly, the T. foenum graecum (fenugreek) seed extracts enhances the pigment production. Quorum sensing regulated swarming motility in Pseudomonas aerugionsa PAO1 was reduced by pea seedling extract while enhanced by the fenugreek seed extracts. These findings suggest that plant metabolites of some legumes interact actively with bacterial quorum sensing and could modulate its associated functions.     

Intraoperative in situ radial artery conduit flow assessment

A technique is described for simple flow assessment of the in situ radial artery conduit during coronary bypass via a small incision. This technique allows morphologic and physiologic direct intraoperative assessment of radial artery quality and expands the use of radial artery during coronary artery surgery.     

Evaluation of brushing cytology in the diagnosis of Helicobacter pylori gastritis

OBJECTIVE: To evaluate clinical utility of rapid urease test (RUT), brash cytology and histology for detecting Helicobacter pylori. STUDY DESIGN: Brush cytology materials were obtained from the antrum of the stomach in 109 patients who suffered from dyspepsia and were candidates for endoscopy. RUT and histology with hematoxylin-eosin staining were performed. Infection status was established by observation of typical HP in cytology or biopsy. RESULTS: A total of 78% ofpatients were diagnosed as positivefor HP organisms using brush cytology; 66% had histologic results positive for HP and 59% for RUT. Observation of typical organism by cytology or histology was the gold standard; 3 tests results were compared. Sensitivity of brush cytology (95%) was higher than that of histology (80.5%) and RUT (72%). CONCLUSION: Gastric brushing cytology provides a sensitive, inexpensive, accurate and easy technique for rapid detection of HP infection. When additional information on severity of mucosal damage or presence of cell atypias is not necessary, histologic examination can be omitted; a cost-effective strategy for assessing HP status might consist of taking antral biopsies, the former for RUT, and performing brush cytology slides, which should be stained and examined only when the RUT result is negative.     

Automatic synchronization and distribution of biological databases and software over low-bandwidth networks among developing countries

Bioinformatics involves the collection, organization and analysis of large amounts of biological data, using networks of computers and databases. Developing countries in the Asia-Pacific region are just moving into this new field of information-based biotechnology. However, the computational infrastructure and network bandwidths available in these countries are still at a basic level compared to that in developed countries. In this study, we assessed the utility of a BitTorrent-based Peer-to-Peer (btP2P) file distribution model for automatic synchronization and distribution of large amounts of biological data among developing countries. The initial country-level nodes in the Asia-Pacific region comprised Thailand, Korea and Singapore. The results showed a significant improvement in download performance using btP2P--three times faster overall download performance than conventional File Transfer Protocol (FTP). This study demonstrated the reliability of btP2P in the dissemination of continuously growing multi-gigabyte biological databases across the three Asia-Pacific countries. The download performance for btP2P can be further improved by including more nodes from other countries into the network. This suggests that the btP2P technology is appropriate for automatic synchronization and distribution of biological databases and software over low-bandwidth networks among developing countries in the Asia-Pacific region. AVAILABILITY: http://everest.bic.nus.edu.sg/p2p/     

Accelerated development of arthritis in mice lacking endothelial selectins

The selectins, along with very late antigen-4 and CD44, have been implicated in mediating leukocyte rolling interactions that lead to joint recruitment and inflammation during the pathogenesis of rheumatoid arthritis. Previously, we showed that P-selectin deficiency in mice resulted in accelerated onset of joint inflammation in the murine collagen-immunized arthritis model. Here, we report that mice deficient either in E-selectin or in E-selectin and P-selectin (E/P-selectin mutant) also exhibit accelerated development of arthritis compared with wild type mice in the CIA model, suggesting that these adhesion molecules perform overlapping functions in regulating joint disease. Analyses of cytokine and chemokine expression in joint tissue from E/P-selectin mutant mice before the onset of joint swelling revealed significantly higher joint levels of macrophage inflammatory protein-1α and IL-1β compared to wild-type mice. IL-1β remained significantly increased in E/P-selectin mutant joint tissue during the early and chronic phases of arthritis. Overall, these data illustrate the novel finding that E-selectin and P-selectin expression can significantly influence cytokine and chemokine production in joint tissue, and suggest that these adhesion molecules play important regulatory roles in the development of arthritis in E/P-selectin mutant mice.     

Proteomic analysis of cellular response to osmotic stress in thick ascending limb of Henle's loop (TALH) cells

Epithelial cells of the thick ascending limb of Henle's loop (TALH cells) play a major role in the urinary concentrating mechanism. They are normally exposed to variable and often very high osmotic stress, which is particularly due to high sodium and chloride reabsorption and very low water permeability of the luminal membrane. It is already established that elevation of the activity of aldose reductase and hence an increase in intracellular sorbitol are indispensable for the osmotic adaptation and stability of the TALH cells. To identify new molecular factors potentially associated with the osmotic stress-resistant phenotype in kidney cells, TALH cells exhibiting low or high levels of resistance to osmotic stress were characterized using proteomic tools. Two-dimensional gel analysis showed a total number of 40 proteins that were differentially expressed in TALH cells under osmotic stress. Twenty-five proteins were overexpressed, whereas 15 proteins showed a down-regulation. Besides the sorbitol pathway enzyme aldose reductase, whose expression was 15 times increased, many other metabolic enzymes like glutathione S-transferase, malate dehydrogenase, lactate dehydrogenase, alpha enolase, glyceraldehyde-3-phosphate dehydrogenase, and triose-phosphate isomerase were up-regulated. Among the cytoskeleton proteins and cytoskeleton-associated proteins vimentin, cytokeratin, tropomyosin 4, and annexins I, II, and V were up-regulated, whereas tubulin and tropomyosins 1, 2, and 3 were down-regulated. The heat shock proteins alpha-crystallin chain B, HSP70, and HSP90 were found to be overexpressed. In contrast to the results in oxidative stress the endoplasmic reticulum stress proteins like glucose-regulated proteins (GRP78, GRP94, and GRP96), calreticulin, and protein-disulfide isomerase were down-regulated under hypertonic stress.     

Neural models for predicting viral vaccine targets

We applied artificial neural networks (ANN) for the prediction of targets of immune responses that are useful for study of vaccine formulations against viral infections. Using a novel data representation, we developed a system termed MULTIPRED that can predict peptide binding to multiple related human leukocyte antigens (HLA). This implementation showed high accuracy in the prediction of the promiscuous peptides that bind to five HLA-A2 allelic variants. MULTIPRED is useful for the identification of peptides that bind multiple HLA-A2 variants as a group. By implementing ANN as a classification engine, we enabled both the prediction of peptides binding to multiple individual HLA-A2 molecules and the prediction of promiscuous binders using a single model. The ANN MULTIPRED predicts peptide binding to HLA-A*0205 with excellent accuracy (area under the receiver operating characteristic curve--AROC>0.90), and to HLA-A*0201, HLA-A*0204 and HLA-A*0206 with high accuracy (AROC>0.85). Antigenic regions with high density of binders ("antigenic hot-spots") represent best targets for vaccine design. MULTIPRED not only predicts individual 9-mer binders but also predicts antigenic hot spots. Two HLA-A2 hot-spots in Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) membrane protein were predicted by using MULTIPRED.     

Role for up-regulated ganglioside biosynthesis and association of Src family kinases with microdomains in retinoic acid-induced differentiation of F9 embryonal carcinoma cells

Mouse F9 embryonal carcinoma cells have been widely used as a model for studying the mechanism of embryonic differentiation, because they are similar to the inner cell mass of early mouse embryos and can differentiate into primitive endoderm (PrE) following retinoic acid (RA) treatment. During F9 cell differentiation, the carbohydrate chains of glycoproteins and their corresponding glycosyltransferases are known to undergo rapid changes. However, there have been no corresponding reports on the expression of gangliosides. We have developed a custom cDNA array that is highly sensitive for the genes responsible for sphingolipid (SL) biosynthesis and metabolism. Using this, we found that, of the 28 selected genes, 26 exhibited increased expression during F9 differentiation into PrE. Although neutral glycosphingolipids (GSLs) were expressed at similar levels before and after differentiation, a greater than 20-fold increase in total ganglioside content was evident in PrE. Glucosylceramide synthase inhibitors (d-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol [d-PDMP] and its analog) depleted gangliosides and this resulted in delayed expression of Disabled-2 (Dab-2), suggesting the involvement of gangliosides in F9 cell differentiation. Disruption of cholesterol-enriched membrane microdomains by methyl-beta-cyclodextrin (MbetaCD) also delayed differentiation. Both MbetaCD and d-PDMP blocked the accumulation of Src family kinases (SFKs) to microdomains. However, d-PDMP did not block flotillin accumulation, yet MbetaCD did. Additionally, confocal laser microscopy revealed the formation of distinct functional microdomains integrating SFKs with gangliosides and cholesterol during PrE differentiation. Thus, we demonstrate the outstanding up-regulation of ganglioside biosynthesis and its importance in the formation of distinct microdomains incorporating SFKs with gangliosides during RA-induced differentiation of F9 cells.