Diagnostic Utility of Temporal Muscle Thickness as a Monitoring Tool for Muscle Wasting in Neurocritical Care

Temporalis muscle (TM) atrophy has emerged as a potential biomarker for muscle wasting. However, its diagnostic utility as a monitoring tool in intensive care remains uncertain. Hence, the objective of this study was to evaluate the diagnostic value of sequential ultrasound- and computed tomography (CT)-based measurements of TM thickness (TMT). With a prospective observational design, we included 40 patients without preexisting sarcopenia admitted to a neurointensive care unit. TMT measurements, performed upon admission and serially every 3–4 days, were correlated with rectus femoris muscle thickness (RFT) ultrasound measurements. Interrater reliability was assessed by Bland Altmann plots and intraclass correlation coefficient (ICC). Analysis of variance was performed in subgroups to evaluate differences in the standard error of measurement (SEM). RFT decline was paralleled by ultrasound- as well as CT-based TMT measurements (TMT to RFT: r = 0.746, p < 0.001; CT-based TMT to ultrasound-based RFT: r = 0.609, p < 0.001). ICC was 0.80 [95% CI 0.74, 0.84] for ultrasound-based assessment and 0.90 [95% CI 0.88, 0.92] for CT-based TMT measurements. Analysis of variance for BMI, Heckmatt score, fluid balance, and agitation showed no evidence of measurement errors in these subgroups. This study demonstrates the clinical feasibility and utility of ultrasound- and CT-based TMT measurements for the assessment of muscle wasting

Risk factors and outcomes after interruption of sedation in subarachnoid hemorrhage (ROUTINE-SAH)—a retrospective cohort study

IntroductionAneurysmal subarachnoid hemorrhage (aSAH) often necessitates prolonged sedation to manage elevated intracranial pressure (ICP) and to prevent secondary brain injury. Optimal timing and biomarkers for predicting adverse events (AEs) during interruption of sedation (IS) after prolonged sedation are not well established. To guide sedation management in aSAH, we aimed to explore the frequency, risk factors, and outcomes of IS in aSAH.MethodsIn a retrospective cohort study, a total of 148 patients with aSAH from January 2015 to April 2020 were screened. In total, 30 patients accounting for 42 IS were included in the analysis. Adverse events (AEs) during IS were used as core outcome measures and were categorized into neurological and non-neurological AEs. Baseline characteristics, clinical parameters before IS, AEs, and functional outcomes were collected using health records. Statistical analysis used generalized linear mixed-effects models with regularization to identify candidate predictors with subsequent bootstrapping to test model stability. As an exploratory analysis, multivariate linear and logistic regression was used to analyze the association between IS and intensive care unit length of stay, duration of mechanical ventilation, and functional outcomes.ResultsThe mean age was 56.9 (SD 14.8) years, and a majority of the patients presented with poor-grade SAH (16/30, 53.3%). Neurological and non-neurological AEs occurred in 60.0% (18/30) of the patients. Timing, number of IS attempts, ICP burden, craniectomy status, level of consciousness, heart rate, cerebral perfusion pressure, oxygen saturation, fraction of inspired oxygen, and temperature were selected as candidate predictors. Through bootstrapping, elapsed time since disease onset (OR 0.85, 95% confidence interval (95% CI) 0.75–0.97), ICP burden (OR 1.24, 95% CI 1.02–1.52), craniectomy (OR 0.68, 95% CI 0.48–0.69), and oxygen saturation (OR, 0.80 0.72–0.89) were revealed as relevant biomarkers for neurological AEs, while none of the pre-selected predictors was robustly associated with non-neurological AEs.ConclusionIn aSAH, complications during the definite withdrawal of sedation are frequent but can potentially be predicted using clinical parameters available at the bedside. Prospective multicenter studies are essential to validate these results and further investigate the impact of IS complications

Effect of (3-Glycidyloxypropyl)Trimethoxysilane (GOPS) on the Electrical Properties of PEDOT:PSS Films

Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) has been reported as a successful functional material in a broad variety of applications. One of the most important advantages of PEDOT:PSS is its water-solubility, which enables simple and environmental friendly manufacturing processes. Unfortunately, this also implies that pristine PEDOT:PSS films are unsuitable for applications in aqueous environments. To reach stability in polar solvents, (3-glycidyloxypropyl)trimethoxysilane (GOPS) is typically used to cross-link PEDOT:PSS. Although this strategy is widely used, its mechanism and effect on PEDOT:PSS performance have not been articulated yet. Here, we present a broad study that provides a better understanding of the effect of GOPS on the electrical and electronic properties of PEDOT:PSS. We show that the GOPS reacts with the sulfonic acid group of the excess PSS, causing a change in the PEDOT:PSS film morphology, while the oxidation level of PEDOT remains unaffected. This is at the origin of the observed conductivity changes. (c) 2017 Wiley Periodicals, Inc

Substrate specificity determinants of human macrophage elastase (MMP-12) based on the 1.1 angstrom crystal structure

Lang R, Kocourek A, Braun M, et al. Substrate specificity determinants of human macrophage elastase (MMP-12) based on the 1.1 angstrom crystal structure. JOURNAL OF MOLECULAR BIOLOGY. 2001;312(4):731-742.The macrophage elastase enzyme (MMP-12) expressed mainly in alveolar macrophages has been identified in the mouse lung as the main destructive agent associated with cigarette smoking, which gives rise to emphysema, both directly via elastin degradation and indirectly by disturbing the proteinase/antiproteinase balance via inactivation of the alpha1-proteinase inhibitor (alpha1-PI), the antagonist of the leukocyte elastase. The catalytic domain of human recombinant MMP-12 has been crystallized in complex with the broad-specificity inhibitor batimastat (BB-94). The crystal structure analysis of this complex, determined using X-ray data to 1.1 Angstrom and refined to an R-value of 0.165, reveals an overall fold similar to that of other MMPs. However, the S-shaped double loop connecting strands III and IV is fixed closer to the beta -sheet and projects its His172 side-chain further into the rather hydrophobic active-site cleft, defining the S3 and the S1-pockets and separating them from each other to a larger extent than is observed in other MMPs. The S2-site is planar, while the characteristic S1'-subsite is a continuous tube rather than a pocket, in which the MMP-12-specific Thr215 replaces a Val residue otherwise highly conserved in almost all other MMPs. This alteration might allow MMP-12 to accept P1' Arg residues, making it unique among MMPs. The active-site cleft of MMP-12 is well equipped to bind and efficiently cleave the AlaMetPhe-LeuGluAla sequence in the reactive-site loop of al-PI, as occurs experimentally. Similarities in contouring and particularly a common surface hydrophobicity both inside and distant from the active-site cleft explain why MMP-12 shares many substrates with matrilysin (MMP-7). The MMP-12 structure is an excellent template for the structure-based design of specific inhibitors for emphysema therapy and for the construction of mutants to clarify the role of this MMP. (C) 2001 Academic Press

Mechanism of inhibition of the human matrix metalloproteinase stromelysin-1 by TIMP-1

Matrix metalloproteinases (MMPs) are zinc endopeptidases that are required for the degradation of extracellular matrix components during normal embryo development, morphogenesis and tissue remodelling. Their proteolytic activities are precisely regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs). Disruption of this balance results in diseases such as arthritis, atherosclerosis, tumour growth and metastasis. Here we report the crystal structure of an MMP-TIMP complex formed between the catalytic domain of human stromelysin-1 (MMP-3) and human TIMP-1. TIMP-1, a 184-residue protein, has the shape of an elongated, contiguous wedge. With its long edge, consisting of five different chain regions, it occupies the entire length of the active-site cleft of MMP-3. The central disulphide-linked segments Cys 1-Thr 2-Cys 3-Val 4 and Ser 68-Val 69 bind to either side of the catalytic zinc. Cys 1 bidentally coordinates this zinc, and the Thr-2 side chain extends into the large specificity pocket of MMP-3. This unusual architecture of the interface between MMP-3 and TIMP-1 suggests new possibilities for designing TIMP variants and synthetic MMP inhibitors with potential therapeutic applications