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Find video protocols related to scientific articles indexed in Pubmed.
Evaluation of the in vitro activity of levornidazole, its metabolites and comparators against clinical anaerobic bacteria.
Int. J. Antimicrob. Agents
PUBLISHED: 06-12-2014
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This study evaluated the in vitro anti-anaerobic activity and spectrum of levornidazole, its metabolites and comparators against 375 clinical isolates of anaerobic bacteria, including Gram-negative bacilli (181 strains), Gram-negative cocci (11 strains), Gram-positive bacilli (139 strains) and Gram-positive cocci (44 strains), covering 34 species. Minimum inhibitory concentrations (MICs) of levornidazole, its five metabolites and three comparators against these anaerobic isolates were determined by the agar dilution method. Minimum bactericidal concentrations (MBCs) of levornidazole and metronidazole were measured against 22 strains of Bacteroides fragilis. Levornidazole showed good activity against B. fragilis, other Bacteroides spp., Clostridium difficile, Clostridium perfringens and Peptostreptococcus magnus, evidenced by MIC90 values of 0.5, 1, 0.25, 2 and 1mg/L, respectively. The activity of levornidazole and the comparators was poor for Veillonella spp. Generally, levornidazole displayed activity similar to or slightly higher than that of metronidazole, ornidazole and dextrornidazole against anaerobic Gram-negative bacilli, Gram-positive bacilli and Gram-positive cocci, especially B. fragilis. Favourable anti-anaerobic activity was also seen with levornidazole metabolites M1 and M4 but not M2, M3 or M5. For the 22 clinical B. fragilis strains, MBC50 and MBC90 values of levornidazole were 2mg/L and 4mg/L, respectively. Both MBC50/MIC50 and MBC90/MIC90 ratios of levornidazole were 4, similar to those of metronidazole. Levornidazole is an important anti-anaerobic option in clinical settings in terms of its potent and broad-spectrum in vitro activity, bactericidal property, and the anti-anaerobic activity of its metabolites M1 and M4.
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Overexpression of microRNA-122 re-sensitizes 5-FU-resistant colon cancer cells to 5-FU through the inhibition of PKM2 in vitro and in vivo.
Cell Biochem. Biophys.
PUBLISHED: 06-06-2014
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5-Fluorouracil (5-FU) is one of the most commonly used anticancer drugs in the treatment of colon cancer. However, acquired chemoresistance is becoming one of the major challenges for patients with advanced stages of colon cancer. Currently, the mechanisms underlying cancer cell resistance to 5-FU are not fully understood. MicroRNAs (miRNA) have been suggested to play important roles in tumorigenesis and drug resistance in colon cancer. In this study, we generated 5-FU-resistant colon cancer cell lines from which we found that miR-122 was downregulated in 5-FU-resistant cells compared with sensitive cells. Meanwhile, the glucose metabolism is significantly upregulated in 5-FU-resistant cells. We report that PKM2 is a direct target of miR-122 in colon cancer cell. Importantly, overexpression of miR-122 in 5-FU-resistant cells resensitizes 5-FU resistance through the inhibition of PKM2 both in vitro and in vivo. In summary, these findings reveal that the dysregulated glucose metabolism contributes to 5-FU resistance, and glycolysis inhibition by miR-122 might be a promising therapeutic strategy to overcome 5-FU resistance.
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Risk factors of Clostridium difficile infections among patients in a university hospital in Shanghai, China.
Anaerobe
PUBLISHED: 03-12-2014
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Clostridium difficile infection (CDI) is an increasing concern in China. However, the risk factors of CDI are rarely reported in the Chinese population. A prospective observational study was therefore conducted among patients with hospital-acquired C. difficile diarrhoea and the risk factors of CDI in a retrospective case-control study. The CDI patients were compared with the non-CDI diarrhoeal patients and those without diarrhoea, respectively. The recurrent CDI patients were compared with the corresponding non-recurrent CDI patients and those without diarrhoea, respectively. Overall, of the 240 patients with hospital-acquired diarrhoea 90 (37.5%) were diagnosed as CDI, and 12 (13.3%) of the 90 CDI patients experienced recurrence. Multivariate analysis indicated that renal disease, malignancy, hypoalbuminemia, prior antibiotic treatment, chemotherapy, nasogastric tube use, length of stay >14 days and intra-abdominal surgery, defined daily dose of antimicrobial agents ?19, prior use of more than three antimicrobial agents, and use of carbapenems were independent risk factors for the first episode of CDI. Use of laxatives, the first- and second-generation narrow-spectrum cephalosporins or metronidazole was identified as protective factors. It is necessary to make testing of C. difficile available as a routine practice and control these risk factors in Chinese hospitals to avoid CDI outbreaks.
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Review of nemonoxacin with special focus on clinical development.
Drug Des Devel Ther
PUBLISHED: 01-01-2014
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Nemonoxacin is a novel C-8-methoxy nonfluorinated quinolone with remarkably enhanced in vitro activity against a wide variety of clinically relevant pathogens, especially gram-positive bacteria, including multidrug-resistant Streptococcus pneumoniae and methicillin-resistant Staphylococcus aureus. It has a low propensity for selecting resistant pathogens than fluoroquinolones, since bacteria become resistant to nemonoxacin only when three different mutations occur in their quinolone resistance-determining regions. Nemonoxacin shows greater efficacy than most of the widely used fluoroquinolones in the murine model of systemic, pulmonary, or ascending urinary tract infection. Nemonoxacin has a sound PK profile in healthy volunteers. It rapidly reaches maximum concentration Cmax 1-2 hours after oral administration in the fasting state and has a relatively long elimination half-life of more than 10 hours, which is similar to fluoroquinolones. Approximately 60%-75% of the administered dose is excreted in unchanged form via kidneys over 24-72 hours. Phase II and III studies of oral nemonoxacin and Phase II studies of intravenous nemonoxacin have been completed in patients with community-acquired pneumonia (CAP), before which the Phase I studies of oral and intravenous nemonoxacin indicated sound tolerance and safety with healthy volunteers. The published results demonstrate that an oral dose of either 500 mg or 750 mg nemonoxacin once daily for 7 days is as effective and safe as levofloxacin 500 mg once daily for 7 days. Nemonoxacin is well-tolerated in patients with CAP. The most common adverse events of oral administration are observed in the gastrointestinal and nervous system, the incidence of which is similar to levofloxacin treatment. The Phase III studies of intravenous nemonoxacin for treating CAP and oral nemonoxacin for diabetic foot infection has been registered with promising outcomes to be expected.
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Toxin-Producing Clostridium difficile Strains as Long-Term Gut Colonizers in Healthy Infants.
J. Clin. Microbiol.
PUBLISHED: 10-30-2013
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Clostridium difficile is a colonizer of the human gut, and toxin-producing strains may cause diarrhea if the infectious burden is heavy. Infants are more frequently colonized than adults, but they rarely develop C. difficile disease. It is not known whether strains of C. difficile differ in the capacity to colonize and persist in the human gut microbiota. Here, we strain typed isolates of C. difficile that had colonized 42 healthy infants followed from birth to ?12 months of age by using PCR ribotyping of the 16S-23S rRNA intergenic spacer region. The isolates were also characterized regarding carriage of the toxin genes tcdA, tcdB, and cdtA/B and the capacity to produce toxin B in vitro. Most strains (71%) were toxin producers, and 51% belonged to the 001 or 014 ribotypes, which often cause disease in adults. These ribotypes were significantly more likely than others to persist for ?6 months in the infant micobiota, and they were isolated from 13/15 children carrying such long-term-colonizing strains. Ribotype 001 strains were often acquired in the first week of life and attained higher population counts than other C. difficile ribotypes in newborn infants feces. Several toxin-negative ribotypes were identified, two of which (GI and GIII) were long-term colonizers, each found in one infant. Our results suggest that the toxin-producing C. difficile ribotypes 001 and 014 have special fitness in the infantile gut microbiota. Toxin-producing strains colonizing young children for long time periods may represent a reservoir for strains causing disease in adults.
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Endostatin suppresses colorectal tumor-induced lymphangiogenesis by inhibiting expression of fibronectin extra domain A and integrin ?9.
J. Cell. Biochem.
PUBLISHED: 04-06-2011
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Endostatin is a natural occurring anti-angiogenic peptide and has been shown to inhibit tumor lymphangiogenesis by suppressing the expression of tumor-stimulating growth factors. We have previously shown that fibronectin alternative extra domain A (EDA) facilitates lymphangiogenesis of colorectal tumors. Since it is known that EDA interacts with integrin ?9 in the lymphatic endothelial cells (LECs), we hypothesized that endostatin may target EDA-integrin ?9 pathway to inhibit colorectal tumor-induced lymphangiogenesis. To test this hypothesis, we examined the effect of endostatin on EDA secreted by SW480 colorectal cancer cells and treated human LECs with different doses of endostatin in the presence of conditional medium from SW480 cells. We found that endostatin significantly reduced EDA secretion by SW480 cells and the expression of integrin ?9 in LECs. Immunofluorescence studies showed that EDA and integrin ?9 colocalized on the cell membrane of LECs and these colocalizations were dramatically reduced by endostatin. Co-immunoprecipitation studies demonstrated that EDA interacted with integrin ?9 in LECs, and showed that endostatin treatment inhibited the formation of EDA-integrin ?9 complex in LECs. Furthermore, we found that the arrangement and polarity of LEC cytoskeletons were destroyed by endostatin substantially, leading to a reduced formation of tube-like structures of LECs and a suppressed chemotaxis of LECs toward SW480 cells. Consistently, EDA and integrin ?9 expressions as well as lymphangiogenesis were significantly suppressed by endostatin in colorectal cancer xenografts. In conclusion, our results suggest that endostatin reduces colorectal tumor-induced lymphangiogenesis, at least in part, by inhibiting EDA-integrin ?9 pathway.
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Antimicrobial susceptibility and heteroresistance in Chinese Clostridium difficile strains.
Anaerobe
PUBLISHED: 01-21-2010
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One hundred and ten toxigenic Clostridium difficile isolates collected between December 2008 and May 2009 at Fudan University Hospital Huashan were analyzed for their antibiotic susceptibility patterns and resistance molecular basis. The heteroresistance to metronidazole in fresh isolates were detected as well. Sixteen different PCR ribotypes were identified with a dominant clone 017 accounting for 37.3% of the isolates, followed by 001 and H. Ribotype 027 was not found but one isolate belonged to ribotype 078. All the isolates were susceptible to vancomycin and piperacillin/tazobactam. Seventy-eight fresh isolates were tested for heteroresistance to metronidazole, 18 (23.1%) of them were found to be positive. Resistance to moxifloxacin, ciprofloxacin, levofloxacin, erythromycin, clindamycin, tetracycline, rifampin, rifaximin and fusidic acid was found in 61.8%, 100%, 66.4%, 85.3%, 88.1%, 62.7%, 29.1%, 29.1% and 8.2% of the isolates, respectively. The isolates of common PCR ribotypes were more frequently resistant than the uncommon ribotypes. The prevalence of resistance genes and mutations among the resistant isolates was as follows: ermB, 69.1%; tetM, 97.1%; gyrA mutation, 63.2%; gyrB mutation, 4.4%; gyrA and gyrB mutation, 32.4%; rpoB mutation, 100%, respectively. The resistance related fusA mutation was only found in one isolate with minimum inhibitory concentration of 4 mg/L.
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Antimicrobial resistance in Clostridium difficile.
Int. J. Antimicrob. Agents
PUBLISHED: 09-21-2009
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Clostridium difficile is the leading cause of hospital-acquired diarrhoea and the number of outbreaks has risen markedly since 2003. The emergence and spread of resistance in C. difficile is complicating treatment and prevention. Most isolates are still susceptible to vancomycin and metronidazole (MTZ), however transient and heteroresistance to MTZ have been reported. The prevalence of resistance to other antimicrobial agents is highly variable in different populations and in different countries, ranging from 0% to 100%. Isolates of common polymerase chain reaction (PCR) ribotypes are more resistant than uncommon ribotypes. Most of the resistance mechanisms that have been identified in C. difficile are similar to those in other Gram-positive bacteria, including mutation, selection and acquisition of the genetic information that encodes resistance. Better antibiotic stewardship and infection control are needed to prevent further spread of resistance in C. difficile.
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Comparison of a commercial multiplex real-time PCR to the cell cytotoxicity neutralization assay for diagnosis of clostridium difficile infections.
J. Clin. Microbiol.
PUBLISHED: 09-09-2009
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A commercial multiplex real-time PCR assay (Cepheid Xpert C. difficile assay) for the diagnosis of Clostridium difficile infection was evaluated. The sensitivity and specificity of the Cepheid assay were 97.1% and 93.0% for fresh stools, using the cell cytotoxicity neutralization assay as the reference. Using PCR ribotyping as the reference for ribotype 027 strains, the corresponding figures were 100% and 98.1%, respectively.
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ERCC5 promoter polymorphisms at -763 and +25 predict the response to oxaliplatin-based chemotherapy in patients with advanced colorectal cancer.
Cancer Biol. Ther.
PUBLISHED: 07-30-2009
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This study aimed to investigate whether single nucleotide polymorphisms (SNPs) in the promoter of the excision repair cross complementation group 5 (ERCC5) gene influences response to oxaliplatin-based chemotherapy. Eighty-three patients with cytologically or histologically confirmed advanced colorectal cancer (CRC), at least one measurable lesion and underwent oxaliplatin-based chemotherapy were studied. To this end, six polymorphisms (-1415C>T, -763A>G, -413C>T, +25A>G, +202C>T, +372C>T) in the ERCC5 promoter were selected for investigation. Genomic DNA was obtained from peripheral blood cells, and polymerase chain reaction-ligation detection reaction was used to analyze these SNPs. The chi(2) test or Fishers exact test was then used to investigate the association between polymorphisms and chemotherapy response. Our results showed that the response rate among patients with the -763GG genotype (72.7%) was significantly higher than that of other genotypes (22.2% for AA genotype, p = 0.008 and 37.2% for AG genotype, p = 0.046 respectively). In addition, the response rate among patients with the +25AA genotype (75%) was significantly higher than that of other genotypes (24.1% for GG genotype, p = 0.004 and 35.7% for AG genotype, p = 0.022 respectively). Patients with the -763A/+25G haplotype had a higher risk of non-response to oxaliplatin chemotherapy compared to those carrying the -763G/+25A haplotype (OR 2.672, 95% CI 1.353-5.278, p = 0.004). However, no genetic variation was observed at site -413, and no significant association was found between the -1415C>T, +202C>T or +372C>T polymorphisms and chemotherapy response. Therefore, these data suggest that ERCC5 promoter polymorphisms at -763 and +25 may be important predictors of response to oxaliplatin chemotherapy.
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Clostridium difficile infections in a Shanghai hospital: antimicrobial resistance, toxin profiles and ribotypes.
Int. J. Antimicrob. Agents
PUBLISHED: 05-02-2009
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The incidence of Clostridium difficile infection (CDI) has risen markedly since 2003, however data from China are limited. A 1-year study was conducted at the University Hospital Huashan to characterise clinical isolates of C. difficile. Of 74 isolates, 56 were from the first episode of CDI (43 A(+)B(+) and 13 A(-)B(+)), 5 were from recurrences and 13 were toxin-negative. No binary toxin or TcdC deletion was detected. All strains were susceptible to metronidazole, vancomycin, meropenem and piperacillin/tazobactam. Resistance to moxifloxacin, ciprofloxacin, levofloxacin, erythromycin, clindamycin, tetracycline, rifampicin and fusidic acid was found in 46.4%, 100%, 60.7%, 71.4%, 71.4%, 35.7%, 25.0% and 17.9% of the isolates, respectively. All moxifloxacin-resistant isolates carried a mutation in either gyrA, gyrB or both. Fourteen different polymerase chain reaction ribotypes were identified, with a specific clone (SH II) accounting for 25% of isolates. No isolates belonged to ribotype 027. The present study is the first systematic survey of clinical C. difficile isolates in China. Further surveillance is required to detect clustering of cases and to monitor the emergence of specific highly virulent clones and resistance.
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Prevalence of qnr determinants among extended-spectrum beta-lactamase-positive Enterobacteriaceae clinical isolates in southern Stockholm, Sweden.
Int. J. Antimicrob. Agents
PUBLISHED: 03-06-2009
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Three hundred and nineteen extended-spectrum beta-lactamase-positive Enterobacteriaceae clinical isolates were screened for qnr genes. Twelve isolates were positive for qnr, including one qnrA1, two qnrB1, three qnrB2, one qnrB4, one qnrB6 and four qnrS1. No qnr-positive strains were identified among the isolates recovered before 2006. The first qnr-positive Escherichia coli was detected from a patient in 2006. qnr genes remained rare in E. coli (6/288; 2.1%), but appeared to be more prevalent in Klebsiella pneumoniae (4/25; 16%) and Enterobacter cloacae (2/3; 66.7%). All qnr-positive isolates were resistant to nalidixic acid while presenting varied susceptibilities to fluoroquinolones. Isolates harbouring qnrB4 or qnrB6 were highly resistant to all the fluoroquinolones tested. Their high-level resistance is associated with multiple chromosomal substitutions in gyrA and parC. Alterations at codons Ser-83 and Asp-87 in GyrA and at codons Ser-80 and Glu-84 in ParC were observed in these isolates.
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Low expression of prolyl hydroxylase 2 is associated with tumor grade and poor prognosis in patients with colorectal cancer.
Exp. Biol. Med. (Maywood)
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Previous studies have indicated that prolyl hydroxylases (PHDs) function as tumor suppressors in human colorectal cancer (CRC), but their clinical and prognostic significance is uncertain. Expressions of PHD1, PHD2, PHD3 and hypoxia-inducible factor (HIF)-1? were detected using immunohistochemistry in an independent CRC cohort of 93 specimens represented on a tissue microarray (TMA). PHD expression levels were correlated with clinicopathological features, patient survival and presumed corresponding HIF-1? expression. Pearson ?(2) test was used to compare clinicopathological features with protein expressions. Survival was estimated by Kaplan-Meier analysis. Cox regression analysis was performed for multivariate analysis of prognostic factors. Of the TMA, 47, 68 and 51 from 93 specimens had low expressions of PHD1, PHD2 and PHD3, respectively. HIF-1? was positively expressed in 75 specimens. Low expression of PHD2 correlated with the high-grade group and a terrible overall survival (P = 0.017 and P = 0.032). Patients who had early stage CRC with low PHD2 expression had a poorer survival (P = 0.015), whereas patients with advanced-stage disease did not demonstrate such a difference (P = 0.691). Besides, PHD2 was uncorrelated with HIF-1? expression. The present study indicated that low expression of PHD2 in CRC predicts poor survival independent of HIF-1?, specifically for patients who have early stage tumors.
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