Cytochrome P450 enzyme RosC catalyzes a multistep oxidation reaction to form the non-active compound 20-carboxyrosamicin

Abstract

The cytochrome P450 enzyme RosC catalyzes a two-step, hydroxylation and alcohol oxidation, oxidation reaction to form the C-20 formyl group in the biosynthesis of a 16-membered macrolide antibiotic rosamicin produced by Micromonospora rosaria IFO13697. RosC is presumed to be involved in the formation of 20-carboxyrosamicin because it has been isolated from the culture broth of M. rosaria. Here, we confirmed that RosC has catalytic activity, with Escherichia coli expressing RosC converting rosamicin into 20-carboxyrosamicin. Therefore, it was revealed that RosC is a multifunctional P450 that catalyzes a three-step oxidation reaction that leads to the formation of the hydroxyl group, formyl group, and carboxyl group at C-20 on the macrolactone ring in the rosamicin biosynthetic pathway. Moreover, the cytochrome P450 enzyme TylI, which is involved in formation of the formyl group of a 16-membered macrolide antibiotic tylosin produced by Streptomyces fradiae ATCC 19609, also converted rosamicin into 20-carboxyrosamicin.

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Changes in bacterial community after application of three different herbicides

Abstract

The native soil microbiota is very important to maintain the quality of that environment, but with the intensive use of agrochemicals, changes in microbial biomass and formation of large quantities of toxic waste were observed in soil, groundwater and surface water. Thereby, the goal of the present study was to evaluate if the selective pressure exerted by the presence of the herbicides atrazine, diuron and 2,4-Dchanges the bacterial community structure of an agricultural soil, using Denaturing Gradient Gel Electrophoresis (DGGE) technique. According to Permanova analysis, it was observed a greater effect of the herbicide persistence time in the soil, the effect of the herbicide class and the effect of interaction between these two factors (persistence time and herbicide class). In conclusion, the results showed that the selective pressure exerted by the presence of these herbicides altered the composition of the local microbiota, being atrazine and diuron that most significantly affected the bacterial community in soil and the herbicide 2,4-D was the one that less altered the microbial community and that bacterial community was reestablished first.

http://ift.tt/2qMrGdO

Stress-responsively modulated ymdAB-clsC operon plays a role in biofilm formation and apramycin susceptibility in Escherichia coli

Abstract

The YmdB protein, an inhibitor of biofilm formation and an inducer of apramycin susceptibility in Escherichia coli (E. coli), is part of a putative operon. However, transcription of this operon and its subsequent effects on biological pathways has not been fully studied. Here, we characterized the operon in terms of promoter activity, transcription, and function. Promoter activity assays identified two new growth- and cold-shock-responsive upstream (PymdA) and inner (PclsC) promoters, respectively. Moreover, investigation of the operon-derived transcripts identified different polycistronic transcripts harboring multiple heterogeneous 3' ends. Overexpression of YmdA or ClsC proteins inhibited biofilm formation and affected apramycin susceptibility, a process dependent on the sucA gene, suggesting that the operon genes or their encoded proteins are functionally linked. Additional investigation of the effects of polycistronic transcripts on the response of E. coli cells to apramycin revealed that transcripts containing ymdA (-213 to + 27) are required for apramycin susceptibility. Thus, ymdAB-clsC is a new stress-responsive operon that plays a role in inhibiting undesired biofilm-forming and antibiotic-resistant bacterial populations.

http://ift.tt/2s5OglT

Retrospective Evaluation of Thromboembolism Risk in Ovarian Cancer Patients Treated with Bevacizumab

Abstract

Background

Bevacizumab is used in addition to standard, platinum-based chemotherapy to treat advanced-stage ovarian cancer patients. Thrombosis is a well-documented adverse effect of bevacizumab.

Objective

The aim of this study was to identify predictive parameters for thromboembolic events in ovarian cancer patients and to explain how bevacizumab increases the risk of these events.

Patients and Methods

Fifty-seven FIGO stage III ovarian cancer patients who underwent cytoreductive surgery and chemotherapy were identified and included in this retrospective study. Twenty-six patients were treated with carboplatin and paclitaxel (CP) only (control group), and 31 patients received CP with bevacizumab (study group). The two groups were compared with regard to thrombosis risk factors and laboratory parameters (total leukocytes, platelet count, hemoglobin, APTT, prothrombin time, INR, fibrinogen levels, D-dimer concentration) before treatment, after each course of chemotherapy, and during thromboembolic events.

Results

Only patients in the group receiving bevacizumab experienced venous thromboembolism (VTE) (p=0.03, χ² test). VTE occurred on average at the 13th cycle of chemotherapy. Patients who experienced VTE had increased BMI before chemotherapy as compared to patients with no thromboembolic event (27.2 vs. 23.3, p=0.005, Mann-Whitney test). D-dimer concentration before treatment was also elevated more in patients affected by VTE (3132.5) than in the non-VTE group (956.43) (p=0.0007, Mann-Whitney test). During the first four administrations of chemotherapy in patients with future VTE, there was a reduction in D-dimer concentration and an extension of APTT. A D-Dimer level higher than 485 ng/mL prior to first chemotherapy indicates for a risk of VTE with 94% sensitivity and 36% specificity.

Conclusions

An elevated D-dimer level and high BMI before chemotherapy are risk factors for VTE in ovarian cancer patients receiving bevacizumab. Bevacizumab possibly increases the risk for VTE.

http://ift.tt/2qOrxL0

Chlamydia muridarum Infection of Macrophages Stimulates IL-1β Secretion and Cell Death via Activation of Caspase-1 in an RIP3-Independent Manner

Chlamydiae are Gram-negative bacteria, which replicate exclusively in the infected host cells. Infection of the host cells by Chlamydiae stimulates the innate immune system leading to an inflammatory response, which is manifested not only by secretion of proinflammatory cytokines such as IL-1 from monocytes, macrophages, and dendritic cells, but also possibly by cell death mediated by Caspase-1 pyroptosis. RIP3 is a molecular switch that determines the development of necrosis or inflammation. However, the involvement of RIP3 in inflammasome activation by Chlamydia muridarum infection has not been clarified. Here, we assessed the role of RIP3 in synergy with Caspase-1 in the induction of IL-1β production in BMDM after either LPS/ATP or Chlamydia muridarum stimulation. The possibility of pyroptosis and necroptosis interplays and the role of RIP3 in IL-1 production during Chlamydia muridarum infection in BMDM was investigated as well. The data indicated that RIP3 is involved in NLRP3 inflammasome activation in LPS/ATP-stimulated BMDMs but not in Chlamydia muridarum infection. Pyroptosis occurred in BMDM after LPS/ATP stimulation or Chlamydia muridarum infection. Moreover, the results also illuminated the important role of the Caspase-1-mediated pyroptosis process which does not involve RIP3. Taken together, these observations may help shed new light on details in inflammatory signaling pathways activated by Chlamydia muridarum infection.

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Comment on “Intraoperative Contrast Enhanced Ultrasound Evaluates the Grade of Glioma”

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Blood assessment of the expression levels of matrix metalloproteinase 9 ( MMP9 ) and its natural inhibitor, TIMP1 genes in Iranian schizophrenic patients

Abstract

Schizophrenia (SCZ) is the most severe chronic mental disorder characterized by abnormal social behavior and disrupted emotions and thought. Like other complex neuropsychological disease, SCZ is caused by a combination of genetic and environmental factors but with a high concordance rate. So far, different genetic factors are revealed to be associated with increased risk of developing SCZ. One of the best ways to investigate the genetic basis of the complex disease is to discover the genetic underlying mechanisms of the defective clinical aspects of the patients. In this regard, genes involved in the developmental mechanisms of the brain such as long-term potentiation (LTP) process that is the basis of synaptic plasticity, memory and learning are considered as strong candidates for SCZ. The aim of the present study was to evaluate the expression levels of two genes that are involved in the LTP regulation in the developing and adult brain, Matrix metallopeptidase9 (MMP9) and TIMP metallopeptidase inhibitor 1 (TIMP1) genes in a blood assessment of schizophrenic patients in comparison to healthy controls by means of quantitative real time PCR. The results of the study showed a significant difference in MMP9/TIPM1 ratio between SCZ patients and healthy controls (P = 0.01). However, no significant difference was detected in the expression level of individual MMP9 and TIMP1 genes in SCZ patients versus healthy controls either in total numbers of subject or in sex based subgroups. Considering the relatively small sample size of the current study, there is a need to replicate this study with further investigations about the mechanism of association of these genes and their functions in the pathogenesis of the SCZ.

http://ift.tt/2sCConY