939 resultados para Pseudo-Addition


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We examined the cerebrospinal fluid penetration of daptomycin after the addition of dexamethasone and its bactericidal efficacy with and without ceftriaxone in an experimental rabbit model of pneumococcal meningitis. The combination of daptomycin with ceftriaxone was the most efficacious regimen for pneumococcal meningitis. The previous addition of dexamethasone affected the antibacterial activity of daptomycin only marginally, either as monotherapy or combined with ceftriaxone, although the penetration of daptomycin into inflamed meninges was significantly reduced from 6 to 2%. Daptomycin with ceftriaxone might be a potential candidate for the empirical therapy of bacterial meningitis, although the activity of this regimen against Listeria monocytogenes remains to be demonstrated.

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An efficient aza-Michael addition of amines to a series of ,-unsaturated ketones, carboxylic esters, nitriles and chalcones has been carried out using perchloric acid supported over silica gel (HClO4-SiO2) at room temperature in high yields under solvent-free reaction conditions.

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Phosphate release kinetics in soils are of global interest because sustainable plant nutrition with phosphate will be a major concern in the future. Dissolution of phosphate-containing minerals induced by a changing rhizosphere equilibrium through proton input is one important mechanism that releases phosphate into bioavailable forms. Our objectives were (i) to determine phosphate release kinetics during H+ addition in calcareous soils of the Schwäbische Alb, Germany, and to assess the influence of (ii) land-use type (grassland vs. forest) and (iii) management intensity on reactive phosphate pools and phosphate release rate constants during H+ addition. Phosphate release kinetics were characterized by a large fast-reacting phosphatepool, which could be attributed to poorly-crystalline calcium phosphates, and a small slow-reacting phosphate pool probably originating from carbonate-bearing hydroxylapatite. Both reactive phosphate pools—as well as total phosphate concentrations (TP) in soil—were greater in grassland than in forest soils. In organically fertilized grassland soils, concentrations of released phosphate were higher than in unfertilized soils, likely because organic fertilizers contain poorly-crystalline phosphate compounds which are further converted into sparingly soluble phosphate forms. Because of an enriched slow-reacting phosphate pool, mown pastures were characterized by a more continuous slow phosphate release reaction in contrast to clear biphasic phosphate release patterns in meadows. Consequently, managing phosphate release kinetics via management measures is a valuable tool to evaluate longer-term P availability in soil in the context of finite rock phosphate reserves on earth.

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Hundreds of genetic variants in SCN5A, the gene coding for the pore-forming subunit of the cardiac sodium channel, Na(v) 1.5, have been described in patients with cardiac channelopathies as well as in individuals from control cohorts. The aim of this study was to characterize the biophysical properties of 2 naturally occurring Na(v) 1.5 variants, p.R689H and p.R689C, found in patients with cardiac arrhythmias and in control individuals. In addition, this study was motivated by the finding of the variant p.R689H in a family with sudden cardiac death (SCD) in children. When expressed in HEK293 cells, most of the sodium current (I(Na)) biophysical properties of both variants were indistinguishable from the wild-type (WT) channels. In both cases, however, an ∼2-fold increase of the tetrodotoxin-sensitive late I(Na) was observed. Action potential simulations and reconstruction of pseudo-ECGs demonstrated that such a subtle increase in the late I(Na) may prolong the QT interval in a nonlinear fashion. In conclusion, despite the fact that the causality link between p.R689H and the phenotype of the studied family cannot be demonstrated, this study supports the notion that subtle alterations of Na(v) 1.5 variants may increase the risk for cardiac arrhythmias.

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Background: Receptor Activator of Nuclear Factor kappaB Ligand (RANKL), a member of the TNF superfamily, contributes to the imbalance of bone resorption and immunoregulation in rheumatoid arthritis. In mice, collagen induced arthritis was exacerbated by IL-3 and anti-IgER antibodies, two mediators activating basophils that are known as effector cells of allergy. Interestingly, our unpublished microarray data revealed that IL-3 induces RANKL mRNA in human basophils. Here we further investigate under which conditions human basophils express surface and/or soluble RANKL. Methods: One part of purified human basophils was co-stimulated with IL-3 and either IgE-dependent or IgE-independent stimuli. The other part of purified basophils was first primed with IL-3 and subsequently triggered with IgE-dependent or IgE-independent stimuli. Expression of surface and soluble RANKL were detected by flow cytometry, ELISA and real-time PCR. Results: By flow cytometry we show that IL-3 induces de novo expression of surface RANKL on human basophils in a time and dose dependent manner. Co-stimulation of basophils with IL-3 and an IgE-dependent stimulus reduces IL-3-induced expression of surface RANKL in a dose dependent manner while IgE-independent stimuli have no effect. In contrast, both IgE-dependent and IgE-independent stimuli enhance expression of surface and soluble RANKL in basophils that were first primed with IL-3 and then triggered. Real-time PCR analysis shows that surface hRANKL1 and soluble hRANKL3 are induced by IL-3 and reduced by co-stimulation with IL-3 and an IgE-dependent stimulus and thus confirms our flow cytometry data. Conclusion: RANKL expression in human basophils is not only dependent on IL-3 and IgE-dependent/IgE-independent stimuli but also on the sequence of their addition to cell culture. Based on our data, we suggest that basophils might have previously unidentified functions in bone resorption or immunoregulation via RANKL.

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OBJECTIVE: The presence of minority nonnucleoside reverse transcriptase inhibitor (NNRTI)-resistant HIV-1 variants prior to antiretroviral therapy (ART) has been linked to virologic failure in treatment-naive patients. DESIGN: We performed a large retrospective study to determine the number of treatment failures that could have been prevented by implementing minority drug-resistant HIV-1 variant analyses in ART-naïve patients in whom no NNRTI resistance mutations were detected by routine resistance testing. METHODS: Of 1608 patients in the Swiss HIV Cohort Study, who have initiated first-line ART with two nucleoside reverse transcriptase inhibitors (NRTIs) and one NNRTI before July 2008, 519 patients were eligible by means of HIV-1 subtype, viral load and sample availability. Key NNRTI drug resistance mutations K103N and Y181C were measured by allele-specific PCR in 208 of 519 randomly chosen patients. RESULTS: Minority K103N and Y181C drug resistance mutations were detected in five out of 190 (2.6%) and 10 out of 201 (5%) patients, respectively. Focusing on 183 patients for whom virologic success or failure could be examined, virologic failure occurred in seven out of 183 (3.8%) patients; minority K103N and/or Y181C variants were present prior to ART initiation in only two of those patients. The NNRTI-containing, first-line ART was effective in 10 patients with preexisting minority NNRTI-resistant HIV-1 variant. CONCLUSION: As revealed in settings of case-control studies, minority NNRTI-resistant HIV-1 variants can have an impact on ART. However, the sole implementation of minority NNRTI-resistant HIV-1 variant analysis in addition to genotypic resistance testing (GRT) cannot be recommended in routine clinical settings. Additional associated risk factors need to be discovered.

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per Johannem `a Lent

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STUDY OBJECTIVE To determine the effectiveness of an esophageal doppler device to non-invasively detect experimental pseudo-electromechanical dissociation (pseudo-EMD). DESIGN Prospective, controlled, laboratory investigation using an asphyxial canine cardiac arrest model and a newly-developed esophageal flat-flow probe doppler unit. INTERVENTIONS Mongrel dogs (20) were instrumented for hemodynamic monitoring. The esophageal doppler probe was placed in the distal esophagus of each animal. Electromechanical dissociation (EMD) was induced by clamping the endotracheal tube. MEASUREMENTS AND MAIN RESULTS A period of pseudo-EMD was defined as the time where cardiac contractility was present, measured by a micromanometer tipped thoracic aortic catheter, without concurrent femoral pulses by palpation. The pseudo-EMD period could be produced consistently in all 20 animals. The characteristic doppler flow sounds were easily heard using the esophageal device in all animals. The time from endotracheal tube clamping until loss of femoral pulses was 622 +/- 96 s; until loss of radial artery doppler signals was 616 +/- 92 s; until loss of esophageal doppler signals was 728 +/- 88 s; and until loss of aortic fluctuations by thoracic aortic catheter was 728 +/- 82 s. The times to loss of esophageal doppler sounds and loss of aortic fluctuations were not significantly different. However, they were significantly longer than the time to loss of femoral pulses (P < 0.02). CONCLUSIONS The canine asphyxial EMD model can be used for short experimental studies of pseudo-EMD. Pseudo-EMD can be consistently and non-invasively detected with this esophageal doppler device. The device is as reliable as a micromanometer tipped aortic arch catheter in detecting pseudo-EMD. The doppler device could potentially be useful in improving recognition of near cardiac arrest in pre-hospital and emergency department settings. Further research on the utility of this device in other models of low-flow states should be performed.

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An unusual increase of Campylobacter concisus in stool cultures provoked an outbreak investigation at the University Hospital of Bern. No epidemiological links were found between cases, and the Campylobacter isolates were clonally unrelated. A change in culture conditions to a hydrogen-rich atmosphere enhancing growth of C. concisus was deemed responsible for this pseudo-outbreak.