The Sick and the Weak: Neuropathies/Myopathies in the Critically Ill.

Critical illness polyneuropathies (CIP) and myopathies (CIM) are common complications of critical illness. Several weakness syndromes are summarized under the term intensive care unit-acquired weakness (ICUAW). We propose a classification of different ICUAW forms (CIM, CIP, sepsis-induced, steroid-denervation myopathy) and pathophysiological mechanisms from clinical and animal model data. Triggers include sepsis, mechanical ventilation, muscle unloading, steroid treatment, or denervation. Some ICUAW forms require stringent diagnostic features; CIM is marked by membrane hypoexcitability, severe atrophy, preferential myosin loss, ultrastructural alterations, and inadequate autophagy activation while myopathies in pure sepsis do not reproduce marked myosin loss. Reduced membrane excitability results from depolarization and ion channel dysfunction. Mitochondrial dysfunction contributes to energy-dependent processes. Ubiquitin proteasome and calpain activation trigger muscle proteolysis and atrophy while protein synthesis is impaired. Myosin loss is more pronounced than actin loss in CIM. Protein quality control is altered by inadequate autophagy. Ca(2+) dysregulation is present through altered Ca(2+) homeostasis. We highlight clinical hallmarks, trigger factors, and potential mechanisms from human studies and animal models that allow separation of risk factors that may trigger distinct mechanisms contributing to weakness. During critical illness, altered inflammatory (cytokines) and metabolic pathways deteriorate muscle function. ICUAW prevention/treatment is limited, e.g., tight glycemic control, delaying nutrition, and early mobilization. Future challenges include identification of primary/secondary events during the time course of critical illness, the interplay between membrane excitability, bioenergetic failure and differential proteolysis, and finding new therapeutic targets by help of tailored animal models.

Dark Energy Survey Year 1 Results: Cosmological Constraints from Cluster Abundances, Weak Lensing, and Galaxy Correlations.

We present the first joint analysis of cluster abundances and auto or cross-correlations of three cosmic tracer fields: galaxy density, weak gravitational lensing shear, and cluster density split by optical richness. From a joint analysis (4×2pt+N) of cluster abundances, three cluster cross-correlations, and the auto correlations of the galaxy density measured from the first year data of the Dark Energy Survey, we obtain Ω_{m}=0.305_{-0.038}^{+0.055} and σ_{8}=0.783_{-0.054}^{+0.064}. This result is consistent with constraints from the DES-Y1 galaxy clustering and weak lensing two-point correlation functions for the flat νΛCDM model. Consequently, we combine cluster abundances and all two-point correlations from across all three cosmic tracer fields (6×2pt+N) and find improved constraints on cosmological parameters as well as on the cluster observable-mass scaling relation. This analysis is an important advance in both optical cluster cosmology and multiprobe analyses of upcoming wide imaging surveys.

Illness perception patterns in patients with Coronary Artery Disease.

The purpose of this study is to identify patterns of illness perception in patients with angiografically verified Coronary Artery Disease. A total of 166 patients (age: 64.4 ± 12.1, 80.7% male) were recruited after angiography. Cluster analysis on the items of the Brief Illness Perception Questionnaire was used to identify patterns of illness perception. The resulting groups were characterized with regard to Quality of Life (MacNew), anxiety and depression (GAD-7 and PHQ-9) and resilience (RS-13). The analysis revealed 4 distinct groups differing with regard to the items covering the perception of the physical and emotional impact of disease. Stronger perceptions in these domains were associated with lower Health Related Quality of Life and higher levels of emotional distress. Group 1 (33.1%) reported the strongest perceptions of the physical and emotional impact of disease and expressed low treatment control, high chronic timeline and significantly higher levels of depression than the other groups. Group 2 (27.7%) was characterized by more moderate perceptions of the emotional and physical impact of disease together with low scores on illness coherence and chronic timeline. Groups 3 (25.3%) and 4 (13.9%) reported smaller physical and emotional impact of illness but differed in chronic timeline. Our results correspond largely to recent findings in patients with other chronic diseases. Further research is needed to explore if stratification of patients according patterns of illness perception can help to inform patient-physician communication strategies.

Health-related quality of life predicts unplanned rehospitalization following coronary revascularization.

BACKGROUND: Health-related quality of life (HRQL) is an increasingly well-recognized measure of health outcome in cardiology. We examined HRQL as a predictor of unplanned rehospitalization for cardiac reasons in patients after coronary revascularization over a period of 3 years. PATIENTS AND METHODS: Out of 791 patients enrolled in the study, 743 completed the MacNew HRQL questionnaire after coronary revascularization. MacNew HRQL scores were used as predictors of unplanned rehospitalization. RESULTS: Within the 3-year follow-up period, 125 patients (16.8 %) were rehospitalized. After adjustment for age, gender, and myocardial infarction as the initiating event, there were significant differences in unplanned rehospitalization rates between patients with low or moderate vs. high MacNew HRQL global scores (HR: 1.8, 95 % CI: 1.2-2.7) and both physical (HR: 2.2, 95 % CI: 1.4-3.5) and social (HR: 1.8, 95 % CI: 1.2-2.7) subscale scores. CONCLUSION: Poor HRQL assessed after coronary revascularization appears to be a powerful predictor of rehospitalization over a 3-year period.

[Pain as an experience constituting body and identity]. / Schmerz als Leib und Identität konstituierendes Erlebnis.

This article focuses on the philosophical perspective of what pain actually is, how pain is defined and what functions pain has. It is unclear, for example, whether pain generally correlates with physical harm, if it is categorically unpleasant, if it can be objectified and how observable neuronal processes correlate with different experiences of pain. Particular attention is paid to investigations concerning neuro-imaging, as well as phenomenological and psychoanalytical considerations. The different functions of pain are presented, especially regarding the extent to which pain represents an experience that constitutes both the body and the identity. Some functions of pain discussed here are: defense and indicator, immediate bodily sensation, perceptibility of the body, self-reassurance of existence, congregating and materializing, psychological regulatory mechanism and communication.

Septic cardiomyopathy in rat LPS-induced endotoxemia: relative contribution of cellular diastolic Ca(2+) removal pathways, myofibrillar biomechanics properties and action of the cardiotonic drug levosimendan.

Cardiac dysfunction is a common complication in sepsis and is characterized by forward pump failure. Hallmarks of septic cardiomyopathy are decreased myofibrillar contractility and reduced Ca(2+) sensitivity but it is still not clear whether reduced pump efficiency is predominantly a diastolic impairment. Moreover, a comprehensive picture of upstream Ca(2+) handling mechanisms and downstream myosin biomechanical parameters is still missing. Ca(2+)-sensitizing agents in sepsis may be promising but mechanistic insights for drugs like levosimendan are scarce. Here, we used an endotoxemic LPS rat model to study mechanisms of sepsis on in vivo hemodynamics, multicellular myofibrillar Ca(2+) sensitivity, in vitro cellular Ca(2+) homeostasis and subcellular actomyosin interaction with intracardiac catheters, force transducers, confocal Fluo-4 Ca(2+) recordings in paced cardiomyocytes, and in vitro motility assay, respectively. Left ventricular ejection fraction and myofibrillar Ca(2+) sensitivity were depressed in LPS animals but restored by levosimendan. Diastolic Ca(2+) transient kinetics was slowed down by LPS but ameliorated by levosimendan. Selectively blocking intracellular and sarcolemmal Ca(2+) extrusion pathways revealed minor contribution of sarcoplasmic reticulum Ca(2+) ATPase (SERCA) to Ca(2+) transient diastole in LPS-evoked sepsis but rather depressed Na(+)/Ca(2+) exchanger and plasmalemmal Ca(2+) ATPase. This was mostly compensated by levosimendan. Actin sliding velocities were depressed in myosin heart extracts from LPS rats. We conclude that endotoxemia specifically impairs sarcolemmal diastolic Ca(2+) extrusion pathways resulting in intracellular diastolic Ca(2+) overload. Levosimendan, apart from stabilizing Ca(2+)-troponin C complexes, potently improves cellular Ca(2+) extrusion in the septic heart.

Assessment of Plasmodium falciparum PfMDR1 transport rates using Fluo-4.

Mutations in the multidrug resistance transporter of Plasmodium falciparum PfMDR1 have been implicated to play a significant role in the emergence of worldwide drug resistance, yet the molecular and biochemical mechanisms of this transporter are not well understood. Although it is generally accepted that drug resistance in P. falciparum is partly associated with PfMDR1 transport activity situated in the membrane of the digestive vacuole, direct estimates of the pump rate of this transport process in the natural environment of the intact host-parasite system have never been analysed. The fluorochrome Fluo-4 is a well-documented surrogate substrate of PfMDR1 and has been found to accumulate by actively being transported into the digestive vacuole of several parasitic strains. In the present study, we designed an approach to use Fluo-4 fluorescence uptake as a measure of compartmental Fluo-4 concentration accumulation in the different compartments of the host-parasite system. We performed a 'reverse Fluo-4 imaging' approach to relate fluorescence intensity to changes in dye concentration rather than Ca(2+) fluctuations and were able to calculate the overall rate of transport for PfMDR1 in Dd2 parasites. With this assay, we provide a powerful method to selectively measure the effect of PfMDR1 mutations on substrate transport kinetics. This will be of high significance for future compound screening to test for new drugs in resistant P. falciparum strains.

Biophotonics-Intraoperative Guidance During Partial Nephrectomy: A Systematic Review and Meta-analysis.

CONTEXT: Partial nephrectomy (PN) with intraoperative guidance by biophotonics has the potential to improve surgical outcomes due to higher precision. However, its value remains unclear since high-level evidence is lacking. OBJECTIVE: To provide a comprehensive analysis of biophotonic techniques used for intraoperative real-time assistance during PN. EVIDENCE ACQUISITION: We performed a comprehensive database search based on the PICO criteria, including studies published before October 2022. Two independent reviewers screened the titles and abstracts followed by full-text screening of eligible studies. For a quantitative analysis, a meta-analysis was conducted. EVIDENCE SYNTHESIS: In total, 35 studies were identified for the qualitative analysis, including 27 studies on near-infrared fluorescence (NIRF) imaging using indocyanine green, four studies on hyperspectral imaging, two studies on folate-targeted molecular imaging, and one study each on optical coherence tomography and 5-aminolevulinic acid. The meta-analysis investigated seven studies on selective arterial clamping using NIRF. There was a significantly shorter warm ischemia time in the NIRF-PN group (mean difference [MD]: -2.9; 95% confidence interval [CI]: -5.6, -0.1; p = 0.04). No differences were noted regarding transfusions (odds ratio [OR]: 0.5; 95% CI: 0.2, 1.7; p = 0.27), positive surgical margins (OR: 0.7; 95% CI: 0.2, 2.0; p = 0.46), or major complications (OR: 0.4; 95% CI: 0.1, 1.2; p = 0.08). In the NIRF-PN group, functional results were favorable at short-term follow-up (MD of glomerular filtration rate decline: 7.6; 95% CI: 4.6, 10.5; p < 0.01), but leveled off at long-term follow-up (MD: 7.0; 95% CI: -2.8, 16.9; p = 0.16). Remarkably, these findings were not confirmed by the included randomized controlled trial. CONCLUSIONS: Biophotonics comprises a heterogeneous group of imaging modalities that serve intraoperative decision-making and guidance. Implementation into clinical practice and cost effectiveness are the limitations that should be addressed by future research. PATIENT SUMMARY: We reviewed the application of biophotonics during partial removal of the kidney in patients with kidney cancer. Our results suggest that these techniques support the surgeon in successfully performing the challenging steps of the procedure.

Holmium Versus Thulium Laser Enucleation of the Prostate: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

CONTEXT: Holmium (HoLEP) and thulium laser enucleation of the prostate (ThuLEP) are the two methods most commonly applied for endoscopic enucleation of the prostate. It remains unclear which of the two is superior in terms of outcome and complications. OBJECTIVE: To compare perioperative and functional outcomes between HoLEP and ThuLEP. EVIDENCE ACQUISITION: A systematic review and meta-analysis were performed according to the recommendations of the Cochrane Collaboration and in line with the PRISMA criteria. A comprehensive database search including MEDLINE, Web of Science, CINAHL, ClinicalTrials.gov, and CENTRAL was conducted according to the PICO criteria. Only randomized controlled trials (RCTs) were considered. All review steps were conducted by two independent reviewers. Risk of bias was assessed using the revised Cochrane tool for RCTs. EVIDENCE SYNTHESIS: The search identified 556 studies, of which four were eligible for qualitative and quantitative analysis, reporting on a total of 579 patients with follow-up of up to 18 months. No significant differences in operating time, enucleation weight, catheterization time, or hospital stay were observed between ThuLEP and HoLEP. The decrease in hemoglobin was significantly lower for ThuLEP (mean difference -0.54 g/dl, 95% confidence interval [CI] -0.93 to -0.15; p < 0.001), but with low certainty of evidence. Transient urinary incontinence was more common for HoLEP (odds ratio 0.56, 95% CI 0.32-0.99; p = 0.045), again with low certainty of evidence. Furthermore, no significant differences were observed for other complications or for functional measures and symptom scores. CONCLUSIONS: ThuLEP and HoLEP offer comparable improvement in symptoms and postoperative voiding parameters. Both procedures are safe and major complications are rare. ThuLEP showed minor advantages for blood loss and the incidence of transient incontinence. This should be interpreted with caution owing to the low certainty of evidence. Therefore, treatment choice should be based on surgeon expertise and local conditions. PATIENT SUMMARY: We reviewed four clinical trials that compared holmium and thulium lasers for treatment to reduce the size of the prostate gland. Our review assessed outcomes and complications. We found that both laser techniques are safe and suitable for reducing symptoms due to an enlarged prostate. Blood loss and short-lasting urinary incontinence were slightly lower after thulium compared to holmium laser treatment.

Cancer risk in HIV-infected individuals on HAART is largely attributed to oncogenic infections and state of immunocompetence.

OBJECTIVES: To estimate the cancer risk of HIV-infected patients in the HAART era with respect to a general reference population and to determine risk factors for malignancy. METHODS: Long term (1996-2009) cancer incidence of the Bonn single centre HIV cohort was compared to the incidence of the reference population of Saarland using standardized incidence ratios (SIR). Poisson regression analysis was used to identify predictors of cancer risk. RESULTS: 1,476 patients entered the cohort, enabling 8,772 person years of observation. 121 tumours in 114 patients, 7 in-situ and 114 invasive cancers, were identified. Malignancies associated with infectious agents such as Kaposi sarcoma (SIRs: male: 5,683; female: 277), non-Hodgkin lymphoma (SIRs male: 35; female: 18), anal cancer (SIRs male: 88; female: 115) as well a cervical carcinoma (SIR female: 4) and Hodgkin?s disease (SIR male: 39) and liver cancer (SIR male: 18) were substantially more frequent in HIV-infected patients than in the general population (p< 0.001, each), whereas all other types of cancer were not increased. Poisson regression identified HAART (incidence rate ratio IRR (95% CI): 0.28 (0.19-0.41), p<0.001), CD4 count (IRR per 100 cells/µl increase: 0.66 (0.57-0.76), p<0.001), hepatitis B (IRR: 2.15 (1.10-4.20), p = 0.046) and age (IRR per 10 year increase: 1.23 (1.03 - 1.46), p = 0.023) as independent predictors for the occurrence of any type of cancer. CONCLUSIONS: HAART and preserved CD4 cells preferentially reduce the risk of malignancies associated with oncogenic infections.

Mechanical properties of cell- and microgel bead-laden oxidized alginate-gelatin hydrogels.

3D-printing technologies, such as biofabrication, capitalize on the homogeneous distribution and growth of cells inside biomaterial hydrogels, ultimately aiming to allow for cell differentiation, matrix remodeling, and functional tissue analogues. However, commonly, only the mechanical properties of the bioinks or matrix materials are assessed, while the detailed influence of cells on the resulting mechanical properties of hydrogels remains insufficiently understood. Here, we investigate the properties of hydrogels containing cells and spherical PAAm microgel beads through multi-modal complex mechanical analyses in the small- and large-strain regimes. We evaluate the individual contributions of different filler concentrations and a non-fibrous oxidized alginate-gelatin hydrogel matrix on the overall mechanical behavior in compression, tension, and shear. Through material modeling, we quantify parameters that describe the highly nonlinear mechanical response of soft composite materials. Our results show that the stiffness significantly drops for cell- and bead concentrations exceeding four million per milliliter hydrogel. In addition, hydrogels with high cell concentrations (≥6 mio ml-1) show more pronounced material nonlinearity for larger strains and faster stress relaxation. Our findings highlight cell concentration as a crucial parameter influencing the final hydrogel mechanics, with implications for microgel bead drug carrier-laden hydrogels, biofabrication, and tissue engineering.

Microarchitecture is severely compromised but motor protein function is preserved in dystrophic mdx skeletal muscle.

Progressive force loss in Duchenne muscular dystrophy is characterized by degeneration/regeneration cycles and fibrosis. Disease progression may involve structural remodeling of muscle tissue. An effect on molecular motorprotein function may also be possible. We used second harmonic generation imaging to reveal vastly altered subcellular sarcomere microarchitecture in intact single dystrophic mdx muscle cells (approximately 1 year old). Myofibril tilting, twisting, and local axis deviations explain at least up to 20% of force drop during unsynchronized contractile activation as judged from cosine angle sums of myofibril orientations within mdx fibers. In contrast, in vitro motility assays showed unaltered sliding velocities of single mdx fiber myosin extracts. Closer quantification of the microarchitecture revealed that dystrophic fibers had significantly more Y-shaped sarcomere irregularities ("verniers") than wild-type fibers (approximately 130/1000 microm(3) vs. approximately 36/1000 microm(3)). In transgenic mini-dystrophin-expressing fibers, ultrastructure was restored (approximately 38/1000 microm(3) counts). We suggest that in aged dystrophic toe muscle, progressive force loss is reflected by a vastly deranged micromorphology that prevents a coordinated and aligned contraction. Second harmonic generation imaging may soon be available in routine clinical diagnostics, and in this work we provide valuable imaging tools to track and quantify ultrastructural worsening in Duchenne muscular dystrophy, and to judge the beneficial effects of possible drug or gene therapies.

Complex mechanical behavior of human articular cartilage and hydrogels for cartilage repair.

The mechanical behavior of cartilage tissue plays a crucial role in physiological mechanotransduction processes of chondrocytes and pathological changes like osteoarthritis. Therefore, intensive research activities focus on the identification of implant substitute materials that mechanically mimic the cartilage extracellular matrix. This, however, requires a thorough understanding of the complex mechanical behavior of both native cartilage and potential substitute materials to treat cartilage lesions. Here, we perform complex multi-modal mechanical analyses of human articular cartilage and two surrogate materials, commercially available ChondroFillerliquid, and oxidized alginate-gelatin (ADA-GEL) hydrogels. We show that all materials exhibit nonlinearity and compression-tension asymmetry. However, while hyaline cartilage yields higher stresses in tension than in compression, ChondroFillerliquid and ADA-GEL exhibit the opposite trend. These characteristics can be attributed to the materials' underlying microstructure: Both cartilage and ChondroFillerliquid contain fibrillar components, but the latter constitutes a bi-phasic structure, where the 60% nonfibrillar hydrogel proportion dominates the mechanical response. Of all materials, ChondroFillerliquid shows the most pronounced viscous effects. The present study provides important insights into the microstructure-property relationship of cartilage substitute materials, with vital implications for mechanically-driven material design in cartilage engineering. In addition, we provide a data set to create mechanical simulation models in the future.

MyoRobot 2.0: An advanced biomechatronics platform for automated, environmentally controlled skeletal muscle single fiber biomechanics assessment employing inbuilt real-time optical imaging.

We present an enhanced version of our previously engineered MyoRobot system for reliable, versatile and automated investigations of skeletal muscle or linear polymer material (bio)mechanics. That previous version already replaced strenuous manual protocols to characterize muscle biomechanics properties and offered automated data analysis. Here, the system was further improved for precise control over experimental temperature and muscle single fiber sarcomere length. Moreover, it also now features the calculation of fiber cross-sectional area via on-the-fly optical diameter measurements using custom-engineered microscope optics. With this optical systems integration, the MyoRobot 2.0 allows to tailor a wealth of recordings for relevant physiological parameters to be sequentially executed in living single myofibers. Research questions include assessing temperature-dependent performance of active or passive biomechanics, or automated control over length-tension or length-velocity relations. The automatically obtained passive stress-strain relationships and elasticity modules are important parameters in (bio)material science. From the plethora of possible applications, we validated the improved MyoRobot 2.0 by assessing temperature-dependent myofibrillar Ca2+ sensitivity, passive axial compliance and Young's modulus. We report a Ca2+ desensitization and a narrowed dynamic range at higher temperatures in murine M. extensor digitorum longus single fibers. In addition, an increased axial mechanical compliance in single muscle fibers with Young's moduli between 40 - 60 kPa was found, compatible with reported physiological ranges. These applications demonstrate the robustness of our MyoRobot 2.0 for facilitated single muscle fiber biomechanics assessment.

Unloaded speed of shortening in voltage-clamped intact skeletal muscle fibers from wt, mdx, and transgenic minidystrophin mice using a novel high-speed acquisition system.

Skeletal muscle unloaded shortening has been indirectly determined in the past. Here, we present a novel high-speed optical tracking technique that allows recording of unloaded shortening in single intact, voltage-clamped mammalian skeletal muscle fibers with 2-ms time resolution. L-type Ca(2+) currents were simultaneously recorded. The time course of shortening was biexponential: a fast initial phase, tau(1), and a slower successive phase, tau(2,) with activation energies of 59 kJ/mol and 47 kJ/mol. Maximum unloaded shortening speed, v(u,max), was faster than that derived using other techniques, e.g., approximately 14.0 L(0) s(-1) at 30 degrees C. Our technique also allowed direct determination of shortening acceleration. We applied our technique to single fibers from C57 wild-type, dystrophic mdx, and minidystrophin-expressing mice to test whether unloaded shortening was affected in the pathophysiological mechanism of Duchenne muscular dystrophy. v(u,max) and a(u,max) values were not significantly different in the three strains, whereas tau(1) and tau(2) were increased in mdx fibers. The results were complemented by myosin heavy and light chain (MLC) determinations that showed the same myosin heavy chain IIA profiles in the interossei muscles from the different strains. In mdx muscle, MLC-1f was significantly increased and MLC-2f and MLC-3f somewhat reduced. Fast initial active shortening seems almost unaffected in mdx muscle.

Degraded collagenase deteriorates islet viability.

OBJECTIVE: The utilization of purified enzyme blends consisting of collagenase class I (CI) and II (CII) and neutral protease is an essential step for clinical islet isolation. Previous studies suggested that the use of enzyme lots containing degraded CI reduced islet release from human pancreata. The present study sought to assess the effect of degraded collagenase on islet function in vitro and posttransplantation. MATERIALS AND METHODS: Crude collagenase was chromatographically separated into CI, CII, and a mixture of degraded CI and CII isomers. Subsequently, classes were recombined to obtain a CII/CI ratio of 0.5. Rat islets were isolated utilizing neutral protease and 20 units of recombined collagenase containing either intact (Ci) or degraded isomers (Cd). RESULTS: Digestion time was reduced utilizing Cd (P < .001). The highest islet yield and lowest islet fragmentation were obtained with Ci (P < .01). Utilization of Cd corresponded to a reduction in viability and in vitro function (NS). Islet transplantation reversed hyperglycemia in diabetic nude mice, but revealed an absence of weight gain in recipients receiving islets isolated using Cd (P < .01). CONCLUSION: This study suggested that islet function posttransplantation is affected by degraded collagenase isomers. This finding has to be considered for the purification process of collagenase.

Weak by the machines: muscle motor protein dysfunction - a side effect of intensive care unit treatment.

Intensive care interventions involve periods of mechanical ventilation, sedation and complete mechanical silencing of patients. Critical illness myopathy (CIM) is an ICU-acquired myopathy that is associated with limb muscle weakness, muscle atrophy, electrical silencing of muscle and motor proteinopathy. The hallmark of CIM is a preferential muscle myosin loss due to increased catabolic and reduced anabolic activity. The ubiquitin proteasome pathway plays an important role, apart from recently identified novel mechanisms affecting non-lysosomal protein degradation or autophagy. CIM is not reproduced by pure disuse atrophy, denervation atrophy, steroid-induced atrophy or septic myopathy, although combinations of high-dose steroids and denervation can mimic CIM. New animal models of critical illness and ICU treatment (i.e. mechanical ventilation and complete immobilization) provide novel insights regarding the time course of protein synthesis and degradation alterations, and the role of protective chaperone activities in the process of myosin loss. Altered mechano-signalling seems involved in triggering a major part of myosin loss in experimental CIM models, and passive loading of muscle potently ameliorates the CIM phenotype. We provide a systematic overview of similarities and distinct differences in the signalling pathways involved in triggering muscle atrophy in CIM and isolated trigger factors. As preferential myosin loss is mostly determined from biochemistry analyses providing no spatial resolution of myosin loss processes within myofibres, we also provide first results monitoring myosin signal intensities during experimental ICU intervention using multi-photon Second Harmonic Generation microscopy. Our results confirm that myosin loss is an evenly distributed process within myofibres rather than being confined to hot spots.

Major intensification of Atlantic overturning circulation at the onset of Paleogene greenhouse warmth.

During the Late Cretaceous and early Cenozoic the Earth experienced prolonged climatic cooling most likely caused by decreasing volcanic activity and atmospheric CO2 levels. However, the causes and mechanisms of subsequent major global warming culminating in the late Paleocene to Eocene greenhouse climate remain enigmatic. We present deep and intermediate water Nd-isotope records from the North and South Atlantic to decipher the control of the opening Atlantic Ocean on ocean circulation and its linkages to the evolution of global climate. The marked convergence of Nd-isotope signatures 59 million years ago indicates a major intensification of deep-water exchange between the North and South Atlantic, which coincided with the turning point of deep-water temperatures towards early Paleogene warming. We propose that this intensification of Atlantic overturning circulation in concert with increased atmospheric CO2 from continental rifting marked a climatic tipping point contributing to a more efficient distribution of heat over the planet.

The MyoRobot: A novel automated biomechatronics system to assess voltage/Ca2+ biosensors and active/passive biomechanics in muscle and biomaterials.

We engineered an automated biomechatronics system, MyoRobot, for robust objective and versatile assessment of muscle or polymer materials (bio-)mechanics. It covers multiple levels of muscle biosensor assessment, e.g. membrane voltage or contractile apparatus Ca2+ ion responses (force resolution 1µN, 0-10mN for the given sensor; [Ca2+] range ~ 100nM-25µM). It replaces previously tedious manual protocols to obtain exhaustive information on active/passive biomechanical properties across various morphological tissue levels. Deciphering mechanisms of muscle weakness requires sophisticated force protocols, dissecting contributions from altered Ca2+ homeostasis, electro-chemical, chemico-mechanical biosensors or visco-elastic components. From whole organ to single fibre levels, experimental demands and hardware requirements increase, limiting biomechanics research potential, as reflected by only few commercial biomechatronics systems that can address resolution, experimental versatility and mostly, automation of force recordings. Our MyoRobot combines optical force transducer technology with high precision 3D actuation (e.g. voice coil, 1µm encoder resolution; stepper motors, 4µm feed motion), and customized control software, enabling modular experimentation packages and automated data pre-analysis. In small bundles and single muscle fibres, we demonstrate automated recordings of (i) caffeine-induced-, (ii) electrical field stimulation (EFS)-induced force, (iii) pCa-force, (iv) slack-tests and (v) passive length-tension curves. The system easily reproduces results from manual systems (two times larger stiffness in slow over fast muscle) and provides novel insights into unloaded shortening velocities (declining with increasing slack lengths). The MyoRobot enables automated complex biomechanics assessment in muscle research. Applications also extend to material sciences, exemplarily shown here for spider silk and collagen biopolymers.

NA+- and K+-channels as molecular targets of the alkaloid ajmaline in skeletal muscle fibres.

BACKGROUND AND PURPOSE: Ajmaline is a widely used antiarrhythmic drug. Its action on voltage-gated ion channels in skeletal muscle is not well documented and we have here elucidated its effects on Na(+) and K(+) channels. EXPERIMENTAL APPROACH: Sodium (I(Na)) and potassium (I(K)) currents in amphibian skeletal muscle fibres were recorded using 'loose-patch' and two-microelectrode voltage clamp techniques (2-MVC). Action potentials were generated using current clamp. KEY RESULTS: Under 'loose patch' clamp conditions, the IC(50) for I(Na) was 23.2 microM with Hill-coefficient h=1.21. For I(K), IC(50) was 9.2 microM, h=0.87. Clinically relevant ajmaline concentrations (1-3 microM) reduced peak I(Na) by approximately 5% but outward I(K) values were reduced by approximately 20%. Na(+) channel steady-state activation and fast inactivation were concentration-dependently shifted towards hyperpolarized potentials ( approximately 10 mV at 25 microM). Inactivation curves were markedly flattened by ajmaline. Peak-I(K) under maintained depolarisation was reduced to approximately 30% of control values by 100 microM ajmaline. I(K) activation time constants were increased at least two-fold. Lower concentrations (10 or 25 microM) reduced steady-state-I(K) slightly but peak-I(K) significantly. Action potential generation threshold was increased by 10 microM ajmaline and repolarisation prolonged. CONCLUSIONS AND IMPLICATIONS: Ajmaline acts differentially on Na(+) and K(+) channels in skeletal muscle. This suggests at least multiple sites of action including the S4 subunit. Our data may provide a first insight into specific mechanisms of ajmaline-ion channel interaction in tissues other than cardiac muscle and could suggest possible side-effects that need to be further evaluated.