Bacteriostatic versus bactericidal antibiotics for patients with serious bacterial infections: systematic review and meta-analysis

Objectives Antibiotics are commonly classified into bactericidal and bacteriostatic agents based on their antimicrobial action. We aimed to assess whether this distinction is clinically relevant. Methods OVID MEDLINE, EMBASE, The Cochrane Central Register of Controlled Trials (CENTRAL) and relevant references and conference proceedings using the Web of Science and Scopus databases were searched for randomized controlled trials comparing bactericidal with bacteriostatic antibiotics for treatment of severe infections. Main outcome measures were clinical cure rates and overall mortality. Abstracts of studies selected in the database search were screened by one reviewer; full-text screening and data extraction were performed by three independent reviewers. Results Thirty-three studies were included. Approximately half of patients were treated with bacteriostatic monotherapy. Infections covered were pneumonia (n = 13), skin and soft tissue infections (n = 8), intra-abdominal infections (n = 4) and others (n = 8). Neither clinical cure rates [risk ratio (RR), 0.99; 95% CI, 0.97-1.01; P = 0.11] nor mortality rates (RR, 0.91; 95% CI, 0.76-1.08; P = 0.28) were different between patients treated with bactericidal drugs and those treated with bacteriostatic drugs. Subgroup analyses showed a benefit for clinical cure rates associated with linezolid and increased mortality associated with tigecycline. In meta-regression, clinical cure rates remained higher in patients treated with linezolid (P = 0.01); tigecycline displayed a close to significant association with increased mortality (P = 0.05) if compared with other bacteriostatic agents. Conclusions The categorization of antibiotics into bacteriostatic and bactericidal is unlikely to be relevant in clinical practice if used for abdominal infections, skin and soft tissue infections and pneumonia. Because we were not able to include studies on meningitis, endocarditis or neutropenia, no conclusion regarding these diseases can be draw

Spatial and temporal variablity of nonmethane hydrocarbon mixing ratios and their relation to photochemical lifetime

The relationship between temporal and spatial variability of C2-C8 nonmethane hydrocarbon mixing ratios and their HO lifetimes (τ) is presented for samples collected during the 1993 North Atlantic Regional Experiment (NARE) and from other urban and remote sites. The C2-C4 alkanes, acetylene and benzene typically define a trend of the form slnx=Aτ-b where slnx is the standard deviation of the ln of the mixing ratio. The relationship extended over a wider range of hydrocarbons in winter. The exponent b ranged in value from 0.2±0.023 for winter urban data where C2-C8 hydrocarbons defined a strongly correlated trend, to 0.56±0.15 for C2-C4 hydrocarbons at a coastal site in Nova Scotia during NARE. The trends are significantly different from that given by the Junge relationship [Junge, 1974]. Data from the Azores do not display such a trend and were likely influenced by local emissions. Variance trends are a useful analytical tool for examining the validity of hydrocarbon measurements

The relation between SAR and the electromagnetic field distribution for heterogeneous exposure conditions

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Research in Geant4 electromagnetic physics design, and its effects on computational performance and quality assurance

The Geant4 toolkit offers a rich variety of electromagnetic physics models; so far the evaluation of this Geant4 domain has been mostly focused on its physics functionality, while the features of its design and their impact on simulation accuracy, computational performance and facilities for verification and validation have not been the object of comparable attention yet, despite the critical role they play in many experimental applications. A new project is in progress to study the application of new design concepts and software techniques in Geant4 electromagnetic physics, and to evaluate how they can improve on the current simulation capabilities. The application of a policy-based class design is investigated as a means to achieve the objective of granular decomposition of processes; this design technique offers various advantages in terms of flexibility of configuration and computational performance. The current Geant4 physics models have been re-implemented according to the new design as a pilot project. The main features of the new design and first results of performance improvement and testing simplification are presented; they are relevant to many Geant4 applications, where computational speed and the containment of resources invested in simulation production and quality assurance play a critical role.Comment: 4 pages, 4 figures and images, to appear in proceedings of the Nuclear Science Symposium and Medical Imaging Conference 2009, Orland

Active sitting with backrest support : is it feasible?

Ergonomics science recommends office chairs that promote active sitting to reduce sitting related complaints. Since current office chairs do not fulfil this recommendation, a new chair was developed by inverting an existing dynamic chair principle. This study compares active sitting on the inverted chair during a simulated computer based office task to two existing dynamic office chairs (n=8). Upper body stability was analysed using Friedman ANOVA (p=.01). Additionally, participants completed a questionnaire to rate their comfort and activity after half a working day. The inverted chair allowed the participants to perform a substantial range of lateral spine flexion (11.5°) with the most stable upper body posture (≤11mm, ≤2°, p≤0.01). The results of this study suggest that the inverted chair supports active sitting with backrest support during computer based office work. However, according to comfort and activity ratings, results should be verified in a future field study with 24 participants.ZHAW Zurich University of Applied SciencesAccepte

Where to place which sensor to measure sedentary behaviour? A method development and comparison among various sensor placements and signal types

Background: Sedentary Behaviour (SB) is associated with several chronic diseases and especially office workers are at increased risk. SB is defined by a sitting or reclined body posture with an energy expenditure ≤1.5 METs. However, current objective methods to measure SB are not consistent with its definition. There is no consensus on which sensor placement and type to be used. Aim: To compare the accuracy of newly developed artificial intelligence models for 15 sensor placements in combination with four signal types (accelerometer only/plus gyroscope and/or magnetometer) to detect posture and physical in-/activity while desk-based activities. Method: Signal features for the model development were extracted from sensor raw data of 30 office workers performing 10 desk-based tasks, each lasting 5 minutes. Direct observation (posture) and indirect calorimetry (in-/activity) served as reference criteria. The best classification model for each sensor was identified and compared among the sensor placements, both using Friedman and post-hoc Wilcoxon tests (p≤0.05). Results: Posture was most accurately measured with a lower body sensor, while in-/activity was most accurately measured with an upper body or waist sensor. The inclusion of additional signal types improved the posture classification for some placements, while the acceleration signal already contained the relevant signal information for the in-/activity classification. Overall, the thigh accelerometer most accurately classified desk-based SB. Conclusion: This study favours, in line with previous work, the measurement of SB with a thigh worn accelerometer, and adds the information that this sensor is also accurate in measuring physical in-/activity while sitting and standing.Swiss National Science FoundationAccepte