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Dive into the research topics where Yoshifumi Takeda is active.

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Featured researches published by Yoshifumi Takeda.


Gut Pathogens | 2010

Emerging trends in the etiology of enteric pathogens as evidenced from an active surveillance of hospitalized diarrhoeal patients in Kolkata, India

G. B. Nair; Thandavarayan Ramamurthy; Bhattacharya Mk; Triveni Krishnan; Sandipan Ganguly; Dhira Rani Saha; Krishnan Rajendran; Byomkesh Manna; Mrinmoy Ghosh; Keinosuke Okamoto; Yoshifumi Takeda

BackgroundThis study was conducted to determine the etiology of diarrhoea in a hospital setting in Kolkata. Active surveillance was conducted for 2 years on two random days per week by enrolling every fifth diarrhoeal patient admitted to the Infectious Diseases and Beliaghata General Hospital in Kolkata.ResultsMost of the patients (76.1%) had acute watery diarrhoea in association with vomiting (77.7%) and some dehydration (92%). Vibrio cholerae O1, Rotavirus and Giardia lamblia were the important causes of diarrhoea. Among Shigella spp, S. flexneri 2a and 3a serotypes were most predominantly isolated. Enteric viruses, EPEC and EAEC were common in children <5 year age group. Atypical EPEC was comparatively higher than the typical EPEC. Multidrug resistance was common among V. cholerae O1 and Shigella spp including tetracycline and ciprofloxacin. Polymicrobial infections were common in all age groups and 27.9% of the diarrhoea patients had no potential pathogen.ConclusionsIncrease in V. cholerae O1 infection among <2 years age group, resistance of V. cholerae O1 to tetracycline, rise of untypable S. flexnerii, higher proportion of atypical EPEC and G. lamblia and polymicrobial etiology are some of the emerging trends observed in this diarrhoeal disease surveillance.


Cellular Microbiology | 2008

Bacterial exotoxins downregulate cathelicidin (hCAP‐18/LL‐37) and human β‐defensin 1 (HBD‐1) expression in the intestinal epithelial cells

Krishnendu Chakraborty; Shubhamoy Ghosh; Hemanta Koley; Asish K. Mukhopadhyay; Thandavarayan Ramamurthy; Dhira Rani Saha; Debashis Mukhopadhyay; Swasti Roychowdhury; Takashi Hamabata; Yoshifumi Takeda; Santasabuj Das

Cathelicidin (hCAP‐18/LL‐37) and β‐defensin 1 (HBD‐1) are human antimicrobial peptides (AMPs) with high basal expression levels, which form the first line of host defence against infections over the epithelial surfaces. The antimicrobial functions owe to their direct microbicidal effects as well as the immunomodulatory role. Pathogenic microorganisms have developed multiple modalities including transcriptional repression to combat this arm of the host immune response. The precise mechanisms and the pathogen‐derived molecules responsible for transcriptional downregulation remain unknown. Here, we have shown that enteric pathogens suppress LL‐37 and HBD‐1 expression in the intestinal epithelial cells (IECs) with Vibrio cholerae and enterotoxigenic Escherichia coli (ETEC) exerting the most dramatic effects. Cholera toxin (CT) and labile toxin (LT), the major virulence proteins of V.u2003cholerae and ETEC, respectively, are predominantly responsible for these effects, both in vitro and in vivo. CT transcriptionally downregulates the AMPs by activating several intracellular signalling pathways involving protein kinase A (PKA), ERK MAPKinase and Cox‐2 downstream of cAMP accumulation and inducible cAMP early repressor (ICER) may mediate this role of CT, at least in part. This is the first report to show transcriptional repression of the AMPs through the activation of cellular signal transduction pathways by well‐known virulence proteins of pathogenic microorganisms.


Epidemiology and Infection | 2011

Role of probiotic in preventing acute diarrhoea in children: a community-based, randomized, double-blind placebo-controlled field trial in an urban slum

Dipika Sur; B. Manna; S. K. Niyogi; T. Ramamurthy; A. Palit; K. Nomoto; T. Takahashi; T. Shima; H. Tsuji; T. Kurakawa; Yoshifumi Takeda; G. B. Nair; Sujit K. Bhattacharya

Acute diarrhoea remains a major public health challenge in developing countries. We examined the role of a probiotic in the prevention of acute diarrhoea to discover if there was an effect directed towards a specific aetiology. A double-blind, randomized, controlled field trial involving 3758 children aged 1-5 years was conducted in an urban slum community in Kolkata, India. Participants were given either a probiotic drink containing Lactobacillus casei strain Shirota or a nutrient drink daily for 12 weeks. They were followed up for another 12 weeks. The primary outcome of this study was the occurrence of first episodes of diarrhoea. We assessed this during 12 weeks of intake of study agent and also for 12 weeks of follow-up. There were 608 subjects with diarrhoea in the probiotic group and 674 subjects in the nutrient group during the study period of 24 weeks. The level of protective efficacy for the probiotic was 14% (95% confidence interval 4-23, P<0·01 in adjusted model). The reduced occurrence of acute diarrhoea in the probiotic group compared to nutrient group was not associated with any specific aetiology. No adverse event was observed in children of either probiotic or nutrient groups. The study suggests that daily intake of a probiotic drink can play a role in prevention of acute diarrhoea in young children in a community setting of a developing country.


Microbiology and Immunology | 2012

Conversion of viable but nonculturable enteric bacteria to culturable by co-culture with eukaryotic cells

Mitsutoshi Senoh; Jayeeta Ghosh-Banerjee; Thandavarayan Ramamurthy; Rita R. Colwell; Shin Ichi Miyoshi; G. Balakrish Nair; Yoshifumi Takeda

Viable but nonculturable (VBNC) Vibrio cholerae non‐O1/non‐O139, V. parahaemolyticus, enterohemorrhagic Escherichia coli, enterotoxigenic E. coli, enteropathogenic E. coli, Shigella flexneri, and Salmonella enterica were converted to the culturable state by co‐culture with selected eukaryotic cells, e.g., HT‐29, Caco‐2, T84, HeLa, Intestine 407, and CHO cells.


Microbiology and Immunology | 2010

Conversion of viable but nonculturable Vibrio cholerae to the culturable state by co-culture with eukaryotic cells

Mitsutoshi Senoh; Jayeeta Ghosh-Banerjee; Thandavarayan Ramamurthy; Takashi Hamabata; Takashi Kurakawa; Makoto Takeda; Rita R. Colwell; G. Balakrish Nair; Yoshifumi Takeda

VBNC Vibrio cholerae O139 VC‐280 obtained by incubation in 1% solution of artificial sea water IO at 4°C for 74 days converted to the culturable state when co‐cultured with CHO cells. Other eukaryotic cell lines, including HT‐29, Caco‐2, T84, HeLa, and Intestine 407, also supported conversion of VBNC cells to the culturable state. Conversion of VBNC V. cholerae O1 N16961 and V. cholerae O139 VC‐280/pG13 to the culturable state, under the same conditions, was also confirmed. When VBNC V. cholerae O139 VC‐280 was incubated in 1% IO at 4°C for up to 91 days, the number of cells converted by co‐culture with CHO cells declined with each additional day of incubation and after 91 days conversion was not observed.


Journal of Clinical Microbiology | 2012

Development and Evaluation of a PCR Assay for Tracking the Emergence and Dissemination of Haitian Variant ctxB in Vibrio cholerae O1 Strains Isolated from Kolkata, India

Arindam Naha; Gururaja P. Pazhani; M. Ganguly; Santanu Ghosh; Thandavarayan Ramamurthy; Ranjan K. Nandy; G. B. Nair; Yoshifumi Takeda; Asish K. Mukhopadhyay

ABSTRACT A PCR-based assay was developed to discriminate the classical, El Tor, and Haitian types of ctxB alleles. Our retrospective study using this newly developed PCR showed that Haitian ctxB first appeared in Kolkata during April 2006, and 93.3% of strains isolated during 2011 carried the new allele. Dendrogram analysis showed a pulsed-field gel electrophoresis (PFGE) pattern of the new variant strains isolated recently that was distinct from the PFGE pattern of the strains carrying classical ctxB that closely matched the 2006 to 2007 variant strains.


Journal of Biological Chemistry | 2009

cAMP Stringently Regulates Human Cathelicidin Antimicrobial Peptide Expression in the Mucosal Epithelial Cells by Activating cAMP-response Element-binding Protein, AP-1, and Inducible cAMP Early Repressor

Krishnendu Chakraborty; Palash Chandra Maity; Alok Kumar Sil; Yoshifumi Takeda; Santasabuj Das

Little is known about the regulation of the innate host defense peptide cathelicidin at the mucosal surfaces. Expression is believed to be transcriptionally regulated, and several cis-acting elements have been identified in the cathelicidin putative promoter. However, the trans-acting factors have not been clearly defined. We have recently reported that bacterial exotoxins suppress cathelicidin expression in sodium butyrate-differentiated intestinal epithelial cells (ECs), and this may be mediated through inducible cAMP early repressor. Here we have shown that cAMP-signaling pathways transcriptionally regulate cathelicidin expression in various ECs. cAMP-response element-binding protein (CREB) and AP-1 (activator protein-1) bind to the cathelicidin putative promoter in vitro. Additionally, transcriptional complexes containing CREB, AP-1, and cathelicidin upstream regulatory sequences are formed within ECs. We have also shown that these complexes may activate cathelicidin promoter and are required for its inducible expression in ECs. This is underscored by the fact that silencing of CREB and AP-1 results in failure of ECs to up-regulate cathelicidin, and hepatitis B virus X protein may use CREB to induce cathelicidin. On the other hand, inducible cAMP early repressor competes with CREB and AP-1 for binding to the cathelicidin promoter and represses transcription, thus functioning as a counter-regulatory mechanism. Finally, both CREB and AP-1 were shown to play major roles in the regulation of cathelicidin in sodium butyrate-differentiated HT-29 cells. This is the first report of a detailed mechanistic study of inducible cathelicidin expression in the mucosal ECs. At the same time, it describes a novel immunomodulatory function of cAMP.


Journal of Medical Microbiology | 2011

Genetic characteristics and changing antimicrobial resistance among Shigella spp. isolated from hospitalized diarrhoeal patients in Kolkata, India.

Santanu Ghosh; Gururaja P. Pazhani; Goutam Chowdhury; Sucharita Guin; Sanjucta Dutta; K. Rajendran; Bhattacharya Mk; Yoshifumi Takeda; Swapan Kumar Niyogi; G. Balakrish Nair; T. Ramamurthy

To study the prevalence pattern and trends in the phenotypic and genetic characteristics of shigellae, we tested 212 isolates isolated from diarrhoeal patients admitted to the Infectious Diseases Hospital, Kolkata, India, from November 2007 to October 2010. Prevalence of Shigella spp. was higher in the >5 years age group (69u200a%) than in children in the <5 years age group (31u200a%). Serotypes 2a, 3a and untypable isolates of Shigella flexneri were frequently detected. An increase in the isolation of Shigella sonnei (15u200a%) is a novel trend in this region. Fluoroquinolone resistance among S. flexneri serotypes 2a, 3a and other serogroups of shigellae is another evolving trend. The set gene was exclusively present in S. flexneri 2a, and the sen gene was detected in all serogroups. PFGE revealed the grouping of S. flexneri isolates according to their serotypes with approximately 80-100u200a% similarity, whilst Shigella dysenteriae type 2 and S. sonnei were clonal in nature. There was no demarcation in the prevalence of serotypes, antimicrobial resistance or clonality between the two age groups.


Journal of Clinical Microbiology | 2013

Molecular Characterization of High-Level-Cholera-Toxin-Producing El Tor Variant Vibrio cholerae Strains in the Zanzibar Archipelago of Tanzania

A. Naha; G. Chowdhury; J. Ghosh-Banerjee; M. Senoh; Toru Takahashi; Benedikt Ley; Kamala Thriemer; Jacqueline L. Deen; Lorenz von Seidlein; Said M. Ali; Ahmed Khatib; T. Ramamurthy; R. K. Nandy; G. B. Nair; Yoshifumi Takeda; Ashish K. Mukhopadhyay

ABSTRACT Analysis of 1,180 diarrheal stool samples in Zanzibar detected 247 Vibrio cholerae O1, Ogawa strains in 2009. Phenotypic traits and PCR-based detection of rstR, rtxC, and tcpA alleles showed that they belonged to the El Tor biotype. Genetic analysis of ctxB of these strains revealed that they were classical type, and production of classical cholera toxin B (CTB) was confirmed by Western blotting. These strains produced more CT than the prototype El Tor and formed a separate cluster by pulsed-field gel electrophoresis (PFGE) analysis.


Clinical Microbiology and Infection | 2013

Culture-independent real-time PCR reveals extensive polymicrobial infections in hospitalized diarrhoea cases in Kolkata, India

A. Sinha; S. SenGupta; S. Guin; S. Dutta; S. Ghosh; P. Mukherjee; A.K. Mukhopadhyay; T. Ramamurthy; Yoshifumi Takeda; T. Kurakawa; K. Nomoto; G.B. Nair; R.K. Nandy

Culture-independent identification of diarrhoeal aetiological agents was performed using DNA harvested from diarrhoeal stool specimens with SYBR-Green-based real-time PCR targeting Vibrio cholerae, Vibrio parahaemolyticus, Campylobacter spp., Shigella spp. and three different pathotypes of diarrhoeagenic Escherichia coli. Conventional culture-dependent methods detected bacterial enteropathogens in 68 of 122 diarrhoeal stool specimens. Of 68 specimens, 59 (86.8%) had a single pathogen and the remaining nine (13.2%) had polymicrobial infections with multiple pathogens. Re-analysis of the 68 specimens by culture-independent real-time PCR methods showed that 25 (36.8%) specimens contained single pathogen and 43 (63.2%) specimens contained mixed infections with multiple pathogens. The prevalence of such high levels of polymicrobial infections would not have been detected without using real-time PCR. Culture-dependent analysis assigned 54 of the 122 selected archived specimens as no known aetiology. However, re-analysis of these samples by real-time PCR showed the presence of single or multiple pathogens among 34 (63%) of these specimens. Estimation of relative pathogen load by real-time PCR in the stool specimens indicated that the inability of conventional culture-dependent methods to detect the pathogens was related to lower colony-forming units of the pathogen, as reflected by lower C(t) values. Detection of high levels of polymicrobial infection by real-time PCR indicates that in the settings like Kolkata and its surroundings, where cholera and other enteric diseases are endemic, the concept of one pathogen one disease might need to be re-evaluated.

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Thandavarayan Ramamurthy

Indian Council of Medical Research

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Hemanta Koley

Indian Council of Medical Research

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Asish K. Mukhopadhyay

Washington University in St. Louis

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Thandavarayan Ramamurthy

Indian Council of Medical Research

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