This work describes the discovery and characterization of a novel series of tricyclic natural product-derived metallo-beta-lactamase inhibitors. Natural product screening of the Bacillus cereus II enzyme identified an extract from a strain of Chaetomium funicola with inhibitory activity against metallo-beta-lactamases. SB236050, SB238569, and SB236049 were successfully extracted and purified from this extract. The most active of these compounds was SB238569, which possessed K(i) values of 79, 17, and 3.4 microM for the Bacillus cereus II, Pseudomonas aeruginosa IMP-1, and Bacteroides fragilis CfiA metallo-beta-lactamases, respectively, yet none of the compounds exhibited any inhibitory activity against the Stenotrophomonas maltophilia L-1 metallo-beta-lactamase (50% inhibitory concentration > 1,000 microM). The lack of activity against angiotensin-converting enzyme and serine beta-lactamases demonstrated the selective nature of these compounds. The crystal structure of SB236050 complexed in the active site of CfiA has been obtained to a resolution of 2.5 A. SB236050 exhibits key polar interactions with Lys184, Asn193, and His162 and a stacking interaction with the indole ring of Trp49 in the flap, which is in the closed conformation over the active site groove. SB236050 and SB238569 also demonstrate good antibacterial synergy with meropenem. Eight micrograms of SB236050 per ml gave rise to an eightfold drop in the MIC of meropenem for two clinical isolates of B. fragilis producing CfiA, making these strains sensitive to meropenem (MIC < or = 4 microg/ml). Consequently, this series of metallo-beta-lactamase inhibitors exhibit the most promising antibacterial synergy activity so far observed against organisms producing metallo-beta-lactamases.
Nitro-substituted 1,3-benzothiazinones (nitro-BTZs) are mechanism-based covalent inhibitors of Mycobacterium tuberculosis decaprenylphosphoryl-β-D-ribose-2′-oxidase (DprE1) with strong antimycobacterial properties. We prepared a number of oxidized and reduced forms of nitro-BTZs to probe the mechanism of inactivation of the enzyme and to identify opportunities for further chemistry. The kinetics of inactivation of DprE1 was examined using an enzymatic assay that monitored reaction progress up to 100 min, permitting compound ranking according to kinact/Ki values. The side-chain at the 2-position and heteroatom identity at the 1-position of the BTZs were found to be important for inhibitory activity. We obtained crystal structures with several compounds covalently bound. The data suggest that steps upstream from the covalent end-points are likely the key determinants of potency and reactivity. The results of protein mass spectrometry using a 7-chloro-nitro-BTZ suggest that nucleophilic reactions at the 7-position do not operate and support a previously proposed mechanism in which BTZ activation by a reduced flavin intermediate is required. Unexpectedly, a hydroxylamino-BTZ showed time-dependent inhibition and mass spectrometry corroborated that this hydroxylamino-BTZ is a mechanism-based suicide inhibitor of DprE1. With this BTZ derivative, we propose a new covalent mechanism of inhibition of DprE1 that takes advantage of the oxidation cycle of the enzyme.
Study characteristicsFollowing our data search in January 2018, we included 10 trials with a total of 844 participants, which we assessed using the standard Cochrane Review protocol. The trials compared the incidence of hernia development around a stoma between a group having a mesh placement at the time of stoma formation and a control group having a conventional stoma formation without mesh placement.
Key resultsWe found that mesh placement around the stoma at the time of stoma formation reduces the incidence of future hernia formation. The participants having a mesh fitted had a similar level of complications as those not having a mesh.
Quality of evidenceWe found low-quality evidence favouring the insertion of a mesh into people having a stoma.Prosthetic mesh placement for the prevention of parastomal herniation (Review)
Objective-To determine the cost of averting death or severe disability by neurosurgical intervention.Design-Retrospective analysis of one year's admissions for neurosurgery; comparison of outcome with expected outcome in the absence of neurosurgical intervention and with the cost of neurosurgery.Setting Results-The cost of neurosurgery in 1983-4 was £1-8 million. In all, 243 deaths or severe disabilities were estimated to have been averted at an average cost of £7325 (range £5000 to £70 000)'. The overall cost per quality adjusted life year (QALY) was £350 (range £34 to >£400 000). The cost of long term care for severely disabled survivors is at least 18-fold greater than the cost ofneurosurgical intervention to avert such disability.Conclusions-In Britain neurosurgery is not expensive in comparison with the costs and benefits of other areas of medicine, and the cost per QALY is unexpectedly low except for severe diffuse head injury, malignant brain tumours, and cerebral metastases. The neurosurgical budget should be assessed in the context of managing a patient in hospital and subsequently in the community.
IntroductionThe costs of running a regional neurosurgical unit,
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