Background: Corticosteroids are frequently used during anesthesia to provide substitution therapy in patients with adrenal insufficiency, as a first-line treatment of several life-threatening conditions, to prevent postoperative nausea and vomiting, and as a component of multimodal analgesia. For these last 2 indications, dexamethasone is most frequently used. Due to the structural resemblance between aminosteroid muscle relaxants and dexamethasone, concerns have been raised about possible corticosteroid inhibition in the reversal of neuromuscular block by sugammadex. We thus investigated the influence of dexamethasone on sugammadex reversal of rocuronium-induced neuromuscular block, which could be relevant in certain clinical situations. Methods: The unique co-culture model of human muscle cells innervated in vitro with rat embryonic spinal cord explants to form functional neuromuscular junctions was first used to explore the effects of 4 and 10 miM rocuronium on muscle contractions, as quantitatively evaluated by counting contraction units in contraction-positive explant co-cultures. Next, equimolar and 3-fold equimolar sugammadex was used to investigate the recovery of contractions from 4 and 10 miM rocuronium block. Finally, 1, 100, and 10 miM dexamethasone (normal, elevated, and high clinical levels) were used to evaluate any effects on the reversal of rocuronium-induced neuromuscular block by sugammadex. Results: Seventy-eight explant co-cultures from 3 time-independent experiments were included, where the number of contractions increased to 10 days of co-culturing. Rocuronium showed a time-dependent effect on depth of neuromuscular block (4 miM rocuronium: baseline, 10, 20 minutes administration; P ( 0.0001), while the dose-dependent effect was close to nominal statistical significance (4, 10 miM; P = 0.080). This was reversed by equimolar concentrations of sugammadex, with further and virtually complete recovery of contractions with 3-fold equimolar sugammadex (P ( 0.0001). Dexamethasone diminished 10 miM sugammadex-induced recovery of contractions from rocuronium-induced neuromuscular block in a dose-dependent manner (P = 0.026) with a higher sugammadex concentration (30 microM) being close to statistically significantly improving recovery (P = 0.065). The highest concentration of dexamethasone decreased the recovery of contractions by equimolar sugammadex by 26%; this effect was more pronounced when 3-fold equimolar (30 %M) sugammadex was used for reversal (48%). Conclusions: This is the first report in which the effects of rocuronium and sugammadex interactions with dexamethasone have been studied in a highly accessible in vitro experimental model of functionally innervated human muscle cells. Sugammadex reverses rocuronium-induced neuromuscular block; however, concomitant addition of high dexamethasone concentrations diminishes the efficiency of sugammadex. Further studies are required to determine the clinical relevance of these interactions.
COBISS.SI-ID: 31243225
Previous animal and human studies have suggested that total plasma sulfide plays a role in the pathophysiology of shock. This study's aim was to determine the value of total plasma sulfide as a marker of shock severity in nonsurgical adult patients admitted to the ICU. Forty-one patients, with various types of shock (septic, cardiogenic, obstructive, and hypovolemic), were included in the study, with an average total plasma sulfide concentration of 23.2 +/- 26.3 microM. Survivors (of shock) had lower total plasma sulfide concentrations than nonsurvivors (13.0 +/- 26.3 vs. 31.9 +/- 31.5 microM; P = 0.02). Total plasma sulfide correlated with dose of administered norepinephrine (R linear = 0.829; P = 0.001) and with Acute Physiology and Chronic Health Evaluation II (APACHE II) score (R cubic = 0.767; P = 0.001). Area under the receiver operating characteristic for total plasma sulfide as a predictor of ICU mortality was 0.739 (confidence interval,0.587-0.892; P = 0.009). Even after correcting for APACHE II score and lactate values, total plasma sulfide correlated with mortality (odds ratio, 1.058; 95% confidence interval, 1.001-1.118; P = 0.045). The study provides evidence that, in nonsurgical adult ICU patients admitted because of any type of shock, total plasma sulfide correlates with administered norepinephrine dose at admission, severity of disease (APACHE II score )/=30 points), and survival outcome.
COBISS.SI-ID: 28925401
Serum starvation is one of the most frequently performed procedures in molecular biology and there are literally thousands of research papers reporting its use. In fact, this method has become so ingrained in certain areas of research that reports often simply state that cells were serum starved without providing any factual details as to how the procedure was carried out. Even so, we quite obviously lack unequivocal terminology, standard protocols, and perhaps most surprisingly, a common conceptual basis when performing serum starvation. Such inconsistencies not only hinder interstudy comparability but can lead to opposing and inconsistent experimental results. Although it is frequently assumed that serum starvation reduces basal activity of cells, available experimental data do not entirely support this notion. To address this important issue, we studied primary humanmyotubes, rat L6 myotubes and human embryonic kidney (HEK)293 cells underdifferent serum starvation conditions and followed time-dependent changesin important signaling pathways such as the extracellular signal-regulated kinase 1/2, the AMP-activated protein kinase, and the mammalian target of rapamycin. Serum starvation induced a swift and dynamic response, which displayed obvious qualitative and quantitative differences across different cell types and experimental conditions despite certain unifying features. There was no uniform reduction in basal signaling activity.Serum starvation clearly represents a major event that triggers a plethora of divergent responses and has therefore great potential to interferewith the experimental results and affect subsequent conclusions.
COBISS.SI-ID: 28890329
Background: In some cases, a definitive confirmation of dysferlinopathy cannotbe achieved by DNA test, because the mutation is detected in one allele only. Patients and methods: Dysferlin expression in skeletal muscle and peripheral blood monocytes (PBM) was studied by Western blot in two unrelated adult patients. The comparative C(T) method (DeltaDeltaC(T) ) was used to calculate relative changes in dysferlin mRNA determined from real-time quantitative PCR experiments. The dysferlin gene was studied by direct sequencing of cDNA and genomic DNA and by Multiplex Ligation-dependent Probe Amplification (MLPA) analysis. Results: A comparable severe reduction in dysferlin was demonstrated in both skeletal muscle and PBM. The expression of dysferlin mRNA was significantly reduced. A novel mutation in exon 47 (c.5289G)C) of the dysferlin gene in the heterozygous state, causing an amino acid change (p.Glu1763Asp), was detected in both patients. The MLPA analysis did not reveal any deletion or duplication. Conclusions: Dysferlin and/or dysferlin mRNA abnormalities are diagnostic for dysferlinopathy when mutational analysis detects a mutation in one allele only. Analysis of dysferlin mRNA can be helpful for distinguishing symptomatic heterozygotes from such patients.
COBISS.SI-ID: 28533721
Edentulous conditions and use of complete dentures alter the functionof jaw muscles, which is presumably reflected in the myosin heavy chain (MyHC) isoform composition. This study is the first dealing with MyHC isoforms expression in edentulous persons with the aim to clarify to which extent the decreased functional load following teeth loss contributes to the changed muscle phenotype during ageing. We analysed MyHC expression in old masseter muscle at decreased and full functional load by comparing age-matchededentulous and dentate subjects. Edentulous subjects had upper and lower complete dentures. Dentate subjects had at least 24 natural teeth in continuous dental arches with two molars present in each quadrant and normal intermaxillary relationship. The adaptive response to the reduced masticatory load was lower numerical and area proportion of MyHC-1 expressing fibres and higher numerical proportion of hybrid fibres in edentulous compared with dentate subjects with no significant difference in the proportion of MyHC-neo-expressing fibres between both groups. We conclude that the observed differences in the proportion of fibre types between denture wearers and dentate subjects cannot be ascribed to degenerative changes intrinsic to the ageing muscle, but to functional differences in muscle activity and to morphological alterations of stomatognathic system accompanying the complete teeth loss.
COBISS.SI-ID: 165036