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Search Results: 1 - 10 of 143489 matches for " Kavindra V Singh "
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Importance of the Collagen Adhesin Ace in Pathogenesis and Protection against Enterococcus faecalis Experimental Endocarditis
Kavindra V. Singh equal contributor,Sreedhar R. Nallapareddy equal contributor,Jouko Sillanp??,Barbara E. Murray
PLOS Pathogens , 2010, DOI: 10.1371/journal.ppat.1000716
Abstract: Ace is an adhesin to collagen from Enterococcus faecalis expressed conditionally after growth in serum or in the presence of collagen. Here, we generated an ace deletion mutant and showed that it was significantly attenuated versus wild-type OG1RF in a mixed infection rat endocarditis model (P<0.0001), while no differences were observed in a peritonitis model. Complemented OG1RFΔace (pAT392::ace) enhanced early (4 h) heart valve colonization versus OG1RFΔace (pAT392) (P = 0.0418), suggesting that Ace expression is important for early attachment. By flow cytometry using specific anti-recombinant Ace (rAce) immunoglobulins (Igs), we showed in vivo expression of Ace by OG1RF cells obtained directly from infected vegetations, consistent with our previous finding of anti-Ace antibodies in E. faecalis endocarditis patient sera. Finally, rats actively immunized against rAce were less susceptible to infection by OG1RF than non-immunized (P = 0.0004) or sham-immunized (P = 0.0475) by CFU counts. Similarly, animals given specific anti-rAce Igs were less likely to develop E. faecalis endocarditis (P = 0.0001) and showed fewer CFU in vegetations (P = 0.0146). In conclusion, we have shown for the first time that Ace is involved in pathogenesis of, and is useful for protection against, E. faecalis experimental endocarditis.
The hylEfm gene in pHylEfm of Enterococcus faecium is not required in pathogenesis of murine peritonitis
Diana Panesso, Maria C Montealegre, Sandra Rincón, Maria F Mojica, Louis B Rice, Kavindra V Singh, Barbara E Murray, Cesar A Arias
BMC Microbiology , 2011, DOI: 10.1186/1471-2180-11-20
Abstract: Five mutants of the hylEfm-region of pHylEfmTX16 from the sequenced endocarditis strain (TX16 [DO]) were obtained using an adaptation of the PheS* system and were evaluated in a commensal strain TX1330RF to which pHylEfmTX16 was transferred by mating; these include i) deletion of hylEfm only; ii) deletion of the gene downstream of hylEfm (down) of unknown function; iii) deletion of hylEfm plus down; iv) deletion of hylEfm-down and two adjacent genes; and v) a 7,534 bp deletion including these four genes plus partial deletion of two others, with replacement by cat. The 7,534 bp deletion did not affect virulence of TX16 in peritonitis but, when pHylEfmTX16Δ7,534 was transferred to the TX1330RF background, the transconjugant was affected in in vitro growth versus TX1330RF(pHylEfmTX16) and was attenuated in virulence; however, neither hylEfm nor hylEfm-down restored wild type function. We did not observe any in vivo effect on virulence of the other deletions of the hylEfm-regionThe four genes of the hylEfm region (including hylEfm) do not mediate the increased virulence conferred by pHylEfmTX16 in murine peritonitis. The use of the markerless counterselection system PheS* should facilitate the genetic manipulation of E. faecium in the future.Enterococcus faecium is a common enterococcal species increasingly isolated from hospital-associated infections in the USA [1]. Compelling evidence suggests that this substantial increase in E. faecium nosocomial infections is due to the worldwide occurrence of a genetic subcluster (designated clonal cluster 17, CC17) which encompasses clones that appear to have evolved independently [2-4]. Several genes have been associated with CC17 E. faecium including i) espEfm, encoding a surface protein which has been associated with increased biofilm formation and urinary tract infection (UTI) [4-6]; ii) some fms genes (two of which are also designated pilA and pilB), encoding putative microbial surface components recognizing adhesive matrix
Contribution of Individual Ebp Pilus Subunits of Enterococcus faecalis OG1RF to Pilus Biogenesis, Biofilm Formation and Urinary Tract Infection
Jouko Sillanp??, Chungyu Chang, Kavindra V. Singh, Maria Camila Montealegre, Sreedhar R. Nallapareddy, Barrett R. Harvey, Hung Ton-That, Barbara E. Murray
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068813
Abstract: The endocarditis and biofilm-associated pilus (Ebp) operon is a component of the core genome of Enterococcus faecalis that has been shown to be important for biofilm formation, adherence to host fibrinogen, collagen and platelets, and in experimental endocarditis and urinary tract infection models. Here, we created single and double deletion mutants of the pilus subunits and sortases; next, by combining western blotting, immunoelectron microscopy, and using ebpR in trans to increase pilus production, we identified EbpA as the tip pilin and EbpB as anchor at the pilus base, the latter attached to cell wall by the housekeeping sortase, SrtA. We also confirmed EbpC and Bps as the major pilin and pilin-specific sortase, respectively, both required for pilus polymerization. Interestingly, pilus length was increased and the number of pili decreased by deleting ebpA, while control overexpression of ebpA in trans restored wild-type levels, suggesting a dual role for EbpA in both initiation and termination of pilus polymerization. We next investigated the contribution of each pilin subunit to biofilm formation and UTI. Significant reduction in biofilm formation was observed with deletion of ebpA or ebpC (P<0.001) while ebpB was found to be dispensable; a similar result was seen in kidney CFUs in experimental UTI (ΔebpA, ΔebpC, P≤0.0093; ΔebpB, non-significant, each vs. OG1RF). Hence, our data provide important structural and functional information about these ubiquitous E. faecalis pili and, based on their demonstrated importance in biofilm and infection, suggest EbpA and EbpC as potential targets for antibody-based therapeutic approaches.
Cell phones and male infertility: a review of recent innovations in technology and consequences
Agarwal, Ashok;Singh, Aspinder;Hamada, Alaa;Kesari, Kavindra;
International braz j urol , 2011, DOI: 10.1590/S1677-55382011000400002
Abstract: cell phones have become a vital part of everyday life. however, the health risks associated with their usage are often overlooked. recently, evidence from several studies supports a growing claim that cell phone usage may have a detrimental effect on sperm parameters leading to decreased male fertility. nonetheless, other studies showed no conclusive link between male infertility and cell phone usage. the ambiguity of such results is attributed to the lack of a centralized assay for measuring inflicted damage caused by cell phones. study design, ethics, and reproducibility are all aspects which must be standardized before any conclusions can be made.
Large scale variation in Enterococcus faecalis illustrated by the genome analysis of strain OG1RF
Agathe Bourgogne, Danielle A Garsin, Xiang Qin, Kavindra V Singh, Jouko Sillanpaa, Shailaja Yerrapragada, Yan Ding, Shannon Dugan-Rocha, Christian Buhay, Hua Shen, Guan Chen, Gabrielle Williams, Donna Muzny, Arash Maadani, Kristina A Fox, Jason Gioia, Lei Chen, Yue Shang, Cesar A Arias, Sreedhar R Nallapareddy, Meng Zhao, Vittal P Prakash, Shahreen Chowdhury, Huaiyang Jiang, Richard A Gibbs, Barbara E Murray, Sarah K Highlander, George M Weinstock
Genome Biology , 2008, DOI: 10.1186/gb-2008-9-7-r110
Abstract: The 2,739,625 base pair chromosome of OG1RF was found to contain approximately 232 kilobases unique to this strain compared to V583, the only publicly available sequenced strain. Almost no mobile genetic elements were found in OG1RF. The 64 areas of divergence were classified into three categories. First, OG1RF carries 39 unique regions, including 2 CRISPR loci and a new WxL locus. Second, we found nine replacements where a sequence specific to V583 was substituted by a sequence specific to OG1RF. For example, the iol operon of OG1RF replaces a possible prophage and the vanB transposon in V583. Finally, we found 16 regions that were present in V583 but missing from OG1RF, including the proposed pathogenicity island, several probable prophages, and the cpsCDEFGHIJK capsular polysaccharide operon. OG1RF was more rapidly but less frequently lethal than V583 in the mouse peritonitis model and considerably outcompeted V583 in a murine model of urinary tract infections.E. faecalis OG1RF carries a number of unique loci compared to V583, but the almost complete lack of mobile genetic elements demonstrates that this is not a defining feature of the species. Additionally, OG1RF's effects in experimental models suggest that mediators of virulence may be diverse between different E. faecalis strains and that virulence is not dependent on the presence of mobile genetic elements.Enterococci have emerged over the past few decades as the second to third most common cause of nosocomial infections, including urinary tract and soft tissue infections, bacteremia, and endocarditis [1-3]. They are well equipped to thrive in environments with heavy antibiotic usage due to both their intrinsic resistance to antibiotics and their talent for swapping genetic information, which allows them to gain and share resistance determinants. Entecococcal infections are predominantly caused by E. faecalis and E. faecium. However, many, if not most, strains of these species are harmless commensals, with
Evaluation of mannitol effect in patients with acute hepatic failure and acute-on-chronic liver failure using conventional MRI, diffusion tensor imaging and in-vivo proton MR spectroscopy
Vivek A Saraswat, Sona Saksena, Kavindra Nath, Pranav Mandal, Jitesh Singh, M Albert Thomas, Ramkishore S Rathore, Rakesh K Gupta
World Journal of Gastroenterology , 2008,
Abstract: AIM: To evaluate the effect of an intravenous bolus of mannitol in altering brain metabolites, brain water content, brain parenchyma volume, cerebrospinal fluid (CSF) volume and clinical signs in controls and in patients with acute liver failure (ALF) and acute-on-chronic liver failure (ACLF), by comparing changes in conventional magnetic resonance imaging (MRI), in vivo proton magnetic resonance spectroscopy (PMRS) and diffusion tensor imaging (DTI) before and after its infusion.METHODS: Five patients each with ALF and ACLF in grade 3 or 4 hepatic encephalopathy and with clinical signs of raised intracranial pressure were studied along with five healthy volunteers. After baseline MRI, an intravenous bolus of 20% mannitol solution was given over 10 min in controls as well as in patients with ALF and ACLF. Repeat MRI for the same position was acquired 30 min after completing the mannitol injection.RESULTS: No statistically significant difference was observed between controls and patients with ALF and ACLF in metabolite ratios, DTI metrics and brain volume or CSF volume following 45 min of mannitol infusion. There was no change in clinical status at the end of post-mannitol imaging.CONCLUSION: The osmotic effect of mannitol did not result in significant reduction of brain water content, alteration in metabolite ratios or any change in the clinical status of these patients during or within 45 min of mannitol infusion.
Cardiovascular Haemodynamics and Some Biochemical Profiles of Endotoxemic Buffalo Calves on Infusion of HSS, Flunixin Meglumine & Blood  [PDF]
J. P. Singh, D. V. Singh
Journal of Biomedical Science and Engineering (JBiSE) , 2018, DOI: 10.4236/jbise.2018.116011
Abstract: Six apparently healthy male buffalo calves aged between 6 months to one year with body weight range of 70 - 140 Kg were used in the present investigation. One animal was used for pilot trial for this group. Five calves were randomly taken into this group. The Eschrechia coli endotoxin infused i/v @5 mg/kg BW/hr for 3 hours to all the animals caused symptoms of restlessness, respiratory distress, snoring, diarrhea, profuse salivation along with the significant fall in systolic, diastolic, pulse and mean arterial venous pressure, hypoproteinemia at 1, 2 & 3 hour and hypoglycemia at 3rd hour i.e., end of endotoxin infusion. Respiration was increased significantly during endotoxin infusion at 2nd & 3rd hour and even afterwards till the end of the observation period i.e. 7 hrs. The treatment with hypertonic saline solution, flunixin meglumine and blood raised (p < 0.05) the systolic, diastolic, pulse, mean arterial, central venous pressure, plasma total protein, Albumin, Glucose and Creatinine to levels either close to or even higher than the normal pre-infusion levels while hematocrit and hemoglobin increased significantly at 7th hour and at 5th, 6th & 7th hour respectively i.e., till the end of the observation period. There was no significant effect on Central Venous Pressure (CVP) and body temperature as measured from rectum.
Effect of abiotic factors on the molluscicidal activity of oleoresin of Zingiber officinale against the snail Lymnaea acuminata  [PDF]
Vijya Singh, Pradeep Kumar, V. K. Singh, D. K. Singh
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.210142
Abstract: Earlier it has been observed that oleoresin of Zingiber officinale is a potent molluscicide ag- ainst Lymnaea acuminata. This snail is the vector of Fasciola species, which cause ende- mic fascioliasis in eastern Uttar Pradesh. As this snail breeds and maintain their population constant through out the year, so that the present study has been designed to find out the effect of variations in some environmental factors in different seasons, on the molluscicidal activity of oleoresin of Zingiber officinale and its relative effect on certain enzymes viz., acetylcholinesterase, acid and alkaline phosphatases in the nervous tissue of the snail Lymnaea acuminata. In this study temperature, pH, dissolve oxygen, free carbon dioxide, conductivity of the water in control, as well as molluscicide treated water, was measured simultaneously. LC50 value of oleoresin was determined in each month of the year. Toxicity of oleoresin in June-July (24 h LC50 16.54-14.28 mgL-1) is highest. Acetylcholinesterase, acid and alkaline phosphatases activity in the nervous tissue of the snails treated with sub-lethal concentration of oleoresin was simultaneously measured. Sig- nificant positive rank correlation, in between the acetylcholinesterase or acid phosphatase activity and LC50 of oleoresin was observed. The pre- sent study conclusively shows that variant abi- otic factors can significantly alter the toxicity of oleoresin of Z. officinale in L. acuminata. The most suitable period for control of L. acuminata is June-July.
Improving Quantitative Measurements using Different Segmentation Techniques for Satellite Images
K. Ravi Kumar,K. Kavindra Kumar,R.S.V.M.Krishna,P. K. Bharadwaj
International Journal of Computer Technology and Applications , 2011,
Abstract: Image segmentation is the most practical approach among all virtually automated image recognition systems. Feature extraction and recognition have numerous applications on telecommunication, weather forecasting, environment exploration and medical diagnosis. This paper deals with different image segmentation algorithms. The quality of satellite image is affected by atmosphere, temperature etc. By the usage of various segmentation techniques ,the image is divided into parts which have strong correlation to reflect the real world body. The different techniques involved in image segmentation are as follows, Edge based image segmentation, Adaptive image thresolding, Watershed segmentation, Region growing segmentation, Quadtree segmentation and Fuzzy cmeans segmentation .Using these techniques the quantitative measurements of the satellite images can be improved
An Augmented Framework for Formal Analysis of Safety Critical Systems  [PDF]
Monika Singh, V. K. Jain
Journal of Software Engineering and Applications (JSEA) , 2017, DOI: 10.4236/jsea.2017.108039
Abstract: This paper presents an augmented framework for analyzing Safety Critical Systems (SCSs) formally. Due to high risk of failure, development process of SCSs is required more attention. Model driven approaches are the one of ways to develop SCSs for accomplishing critical and complex function what SCSs are supposed to do. Two model driven approaches: Unified Modeling Language (UML) and Formal Methods are combined in proposed framework which enables the analysis, designing and testing safety properties of SCSs more rigorously in order to reduce the ambiguities and enhance the correctness and completeness of SCSs. A real time case study has been discussed in order to validate the proposed framework.
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