Tigecycline Potentiates Clarithromycin Activity against Mycobacterium avium In Vitro

The in vitro activities of clarithromycin and tigecycline alone and in combination against Mycobacterium avium were assessed. The activity of clarithromycin was time dependent, highly variable, and often resulted in clarithromycin resistance. Tigecycline showed concentration-dependent activity, and mycobacterial killing could only be achieved at high concentrations. Tigecycline enhanced clarithromycin activity against M. avium and prevented clarithromycin resistance. Whether there is clinical usefulness of tigecycline in the treatment of M. avium infections needs further study.     

Structural insights into biased G protein-coupled receptor signaling revealed by fluorescence spectroscopy

G protein-coupled receptors (GPCRs) are seven-transmembrane proteins that mediate most cellular responses to hormones and neurotransmitters, representing the largest group of therapeutic targets. Recent studies show that some GPCRs signal through both G protein and arrestin pathways in a ligand-specific manner. Ligands that direct signaling through a specific pathway are known as biased ligands. The arginine-vasopressin type 2 receptor (V2R), a prototypical peptide-activated GPCR, is an ideal model system to investigate the structural basis of biased signaling. Although the native hormone arginine-vasopressin leads to activation of both the stimulatory G protein (Gs) for the adenylyl cyclase and arrestin pathways, synthetic ligands exhibit highly biased signaling through either Gs alone or arrestin alone. We used purified V2R stabilized in neutral amphipols and developed fluorescence-based assays to investigate the structural basis of biased signaling for the V2R. Our studies demonstrate that the Gs-biased agonist stabilizes a conformation that is distinct from that stabilized by the arrestin-biased agonists. This study provides unique insights into the structural mechanisms of GPCR activation by biased ligands that may be relevant to the design of pathway-biased drugs.     

The tower of Babel: Survey on concepts and terminology in electrical status epilepticus in sleep and continuous spikes and waves during sleep in North America

Purpose: The terms “electrical status epilepticus during sleep (ESES)” and “continuous spikes and waves during sleep (CSWS)” have been used interchangeably when referring to related but different concepts. In addition, the quantification of epileptiform activity has not been standardized, and different approaches to quantification have been used. The aim of this study was to evaluate the extent to which pediatric neurologists and epileptologists use a homogeneous terminology and conceptualization in CSWS and ESES and to characterize the current understanding of these conditions. Methods: A survey addressing the use of terminology in “ESES” and “CSWS” and the understanding of related concepts was distributed online to all members of the Child Neurology Society and the American Epilepsy Society mailing lists. Surveys were self‐administered and collected using an online survey website ( http://www.surveymonkey.com ). Key Findings: Two hundred nineteen surveys were completed, 137 from the Child Neurology Society mailing list and 82 from the American Epilepsy Society mailing list. ESES and CSWS were considered synonymous by 117 respondents, not synonymous by 61, 21 respondents did not know, and 20 did not respond. Most respondents (63.1%) considered CSWS as a devastating epileptic encephalopathy with severe sequelae even if treated correctly, but 25.1% of respondents indicated that it does not leave sequelae if epilepsy was treated early and another 11.8% noted that cognitive difficulties resolved with age. Cognitive and/or language regression were considered mandatory for the diagnosis of CSWS by only 27% of the respondents. The diagnosis of CSWS was based on electroencephalography (EEG) assessment alone by 31% of respondents. Respondents used different methods for calculation of the epileptiform activity, different EEG samples for calculation, and considered differently the lateralized epileptiform activity. The cut‐off values for percentage of the sleep record occupied by spike‐waves were variable depending on the respondent. There was no agreement on whether these cutoff values were mandatory for the diagnosis of ESES and CSWS. Significance: Our data show that the professionals caring for children with ESES and CSWS in North America use the terms, concepts, and defining features heterogeneously. The lack of a common language may complicate communication among clinicians and jeopardize research in this field. We anticipate that our data will fuel the development of much needed common terminology and conceptualization of ESES and CSWS.     

Arm load magnitude affects selective shoulder muscle activation

For isometric tasks, shoulder muscle forces are assumed to scale linearly with the external arm load magnitude, i.e., muscle force ratios are constant. Inverse dynamic modeling generally predicts such linear scaling behavior, with a critical role for the arbitrary load sharing criteria, i.e., the “cost function”. We tested the linearity of the relation between external load magnitude exerted on the humerus and shoulder muscle activation. Six isometric force levels ranging from 17 to 100% of maximal arm force were exerted in 24 directions in a plane perpendicular to the longitudinal axis of the humerus. The direction of maximum muscle activation, the experimentally observed so called Principal Action (PA), was determined for each force magnitude in 12 healthy subjects. This experiment was also simulated with the Delft Shoulder and Elbow Model (DSEM) using two cost functions: (1) minimizing muscle stress and (2) a compound, energy related cost function. PA, both experimental (PA_exp) and simulated (PA_sim), was expected not to change with arm forces magnitudes. PA_exp of the mm. trapezius pars descendens, deltoideus pars medialis and teres major changed substantially as a function of external force magnitude, indicating external load dependency of shoulder muscle activation. In DSEM simulations, using the stress cost function, small non-linearities in the muscle force–external load dependency were observed, originating from gravitational forces working on clavicular and scapular bone masses. More pronounced non-linearities were introduced by using the compound energy related cost function, but no similarity was observed between PA_exp and PA_sim.     

The acceptability of waiting times for elective general surgery and the appropriateness of prioritising patients

Background  

Problematic waiting lists in public health care threaten the equity and timeliness of care provision in several countries. This study assesses different stakeholders' views on the acceptability of waiting lists in health care, their preferences for priority care of patients, and their judgements on acceptable waiting times for surgical patients.     

Risk of health complaints and disabilities among Dutch firefighters

Objectives: The purpose of the present study was threefold: (1) to compare the work demands on firefighters (FFs) and office workers (OWs), (2) to compare the prevalence of health complaints and disabilities in the work situation in these two groups, and (3) to explore the effect of work demands on the risk of health complaints. Methods: Self-reported information was gathered from 1,624 FFs (55% response) and 630 OWs (80% response), at the same fire departments in different regions of the Netherlands, on work demands (sitting, and biomechanically and energetically demanding activities and 24-h shifts), health complaints and disabilities. First, we compared the work demands and prevalence rates of health complaints and related disabilities in the two groups, then we explored the risk of health complaints in workers with high and low exposure to work demands. Results: Compared with office workers, FFs reported: (1) less exposure to sitting and more to biomechanically and energetically demanding activities, (2) more knee (OWs 14% vs FFs 20%) and ankle (3% vs 10%) complaints and disabilities resulting from back complaints (30% vs 47%), and (3) less hypertension (7% vs 5%), stomach (13% vs 7%), heart (6% vs 2%), neck (26% vs 16%), shoulder (16% vs 14%) and arm (14% vs 6%) complaints. A higher risk of subjective fatigue was found in workers highly exposed to energetically demanding activities, and of neck, shoulder and arm complaints in workers highly exposed to sitting. Conclusions: Firefighters reported higher physical demands (with the exception of sitting) than office workers did. The prevalence rate of certain complaints or disabilities among FFs was higher (knee and ankle complaints and disabilities related to back complaints) or lower (hypertension, stomach, heart, neck, shoulder and arm complaints) than among OWs. The results suggest that exposure to highly biomechanically demanding activities might cause an increased risk of knee and ankle complaints and that exposure to highly energetically demanding activities might increase the risk of subjective fatigue.     

Baseline fat fraction is a strong predictor of disease progression in Becker muscular dystrophy

In Becker muscular dystrophy (BMD), muscle weakness progresses relatively slowly, with a highly variable rate among patients. This complicates clinical trials, as clinically relevant changes are difficult to capture within the typical duration of a trial. Therefore, predictors for disease progression are needed. We assessed if temporal increase of fat fraction (FF) in BMD follows a sigmoidal trajectory and whether fat fraction at baseline (FFbase) could therefore predict FF increase after 2 years (ΔFF). Thereafter, for two different MR-based parameters, we tested the additional predictive value to FFbase. We used 3-T Dixon data from the upper and lower leg, and multiecho spin-echo MRI and 7-T ³¹P MRS datasets from the lower leg, acquired in 24 BMD patients (age: 41.4 [SD 12.8] years). We assessed the pattern of increase in FF using mixed-effects modelling. Subsequently, we tested if indicators of muscle damage like standard deviation in water T₂ (stdT₂) and the phosphodiester (PDE) over ATP ratio at baseline had additional value to FFbase for predicting ∆FF. The association between FFbase and ΔFF was described by the derivative of a sigmoid function and resulted in a peak ΔFF around 0.45 FFbase (fourth-order polynomial term: t = 3.7, p < .001). StdT₂ and PDE/ATP were not significantly associated with ∆FF if FFbase was included in the model. The relationship between FFbase and ∆FF suggests a sigmoidal trajectory of the increase in FF over time in BMD, similar to that described for Duchenne muscular dystrophy. Our results can be used to identify muscles (or patients) that are in the fast progressing stage of the disease, thereby facilitating the conduct of clinical trials.     

C5a anaphylatoxin is a major regulator of activating versus inhibitory FcgammaRs in immune complex-induced lung disease

IgG Fc receptors (FcgammaRs, especially FcgammaRIII) and complement (in particular, C5a anaphylatoxin) are critical effectors of the acute inflammatory response to immune complexes (ICs). However, it is unknown whether and how these two key components can interact with each other in vivo. We use here a mouse model of the acute pulmonary IC hypersensitivity reaction to analyze their potential interaction. FcgammaRIII and C5aR are coexpressed on alveolar macrophages (AMs), and both FcgammaRIII and C5aR mutant mice display impaired immune responses. We find that recombinant human C5a (rhC5a) can control inverse expression of various FcgammaRs, and costimulation of ICs with rhC5a results in strong enhancement of FcgammaRIII-triggered cellular activation in vitro and in vivo. Moreover, we show here that early IC-induced bioactive C5a, and its interaction with C5aR, causes induction of activating FcgammaRIII and suppression of inhibitory FcgammaRII on AMs that appears crucial for efficient cytokine production and neutrophil recruitment in lung pathology. Therefore, C5a, which is a potent chemoattractant, has a broader critical function in regulating the inhibitory/activating FcgammaRII/III receptor pair to connect complement and FcgammaR effector pathways in immune inflammation.     

Targeted drug delivery to enhance efficacy and shorten treatment duration in disseminated Mycobacterium avium infection in mice

OBJECTIVES: Improvement of the efficacy of drug treatment in mycobacterial infection by the development and application of targeted drug delivery. METHODS: In disseminated Mycobacterium avium infection in mice, the relative efficacy of the antimycobacterial agents that are currently used in combination therapy was investigated. Next, the effect of the addition of targeted delivery of amikacin to the infected tissues in the initial phase of treatment was studied. Amikacin was chosen because of its unique rapid and high mycobacterial killing capacity. As drug delivery tool, long-circulating sterically stabilized liposomes were used. RESULTS: Treatment with clarithromycin alone daily (6 days a week) slowly killed most of the mycobacteria in the lung, liver, spleen, inguinal and mesenterial lymph nodes. However, after 24 weeks of treatment, persistence of substantial numbers of mycobacteria in the infected organs was observed. The addition of ethambutol to the clarithromycin regimen did not significantly enhance the efficacy of treatment, neither did rifampicin as a third agent. In contrast, the addition of liposomal amikacin in the initial phase of therapy resulted in rapid and complete elimination of the mycobacteria in all infected organs within 12 weeks of treatment without relapse of infection. As a result, total treatment duration could be significantly reduced to 12 weeks. CONCLUSIONS: In M. avium infection in mice, the approach of targeted drug delivery was successful. The rapid decrease in the mycobacterial load followed by complete killing, including the persistent mycobacteria considered responsible for relapse of infection, allows a significant reduction of the total treatment duration.