Sarcopenia: Aging-Related Loss of Muscle Mass and Function.

Sarcopenia is a loss of muscle mass and function in the elderly that reduces mobility, diminishes quality of life, and can lead to fall-related injuries, which require costly hospitalization and extended rehabilitation. This review focuses on the aging-related structural changes and mechanisms at cellular and subcellular levels underlying changes in the individual motor unit: specifically, the perikaryon of the α-motoneuron, its neuromuscular junction(s), and the muscle fibers that it innervates. Loss of muscle mass with aging, which is largely due to the progressive loss of motoneurons, is associated with reduced muscle fiber number and size. Muscle function progressively declines because motoneuron loss is not adequately compensated by reinnervation of muscle fibers by the remaining motoneurons. At the intracellular level, key factors are qualitative changes in posttranslational modifications of muscle proteins and the loss of coordinated control between contractile, mitochondrial, and sarcoplasmic reticulum protein expression. Quantitative and qualitative changes in skeletal muscle during the process of aging also have been implicated in the pathogenesis of acquired and hereditary neuromuscular disorders. In experimental models, specific intervention strategies have shown encouraging results on limiting deterioration of motor unit structure and function under conditions of impaired innervation. Translated to the clinic, if these or similar interventions, by saving muscle and improving mobility, could help alleviate sarcopenia in the elderly, there would be both great humanitarian benefits and large cost savings for health care systems.

Tackling Brain and Muscle Dysfunction in Acute Respiratory Distress Syndrome Survivors: NHLBI Workshop Report.

Acute respiratory distress syndrome (ARDS) is associated with long-term impairments in brain and muscle function that significantly impact the quality of life of those who survive the acute illness. The mechanisms underlying these impairments are not yet well understood, and evidence-based interventions to minimize the burden on patients remain unproved. The NHLBI of the NIH assembled a workshop in April 2023 to review the state of the science regarding ARDS-associated brain and muscle dysfunction, to identify gaps in current knowledge, and to determine priorities for future investigation. The workshop included presentations by scientific leaders across the translational science spectrum and was open to the public as well as the scientific community. This report describes the themes discussed at the workshop as well as recommendations to advance the field toward the goal of improving the health and well-being of ARDS survivors.

Management of complications after skin surgery relevant for melanoma in the trunk and extremities during the COVID-19 pandemic: a case series report.

BACKGROUND: Patients with melanoma have been found to be at greater risk of adverse outcomes including mortality after contacting COVID-19. Management of postsurgical complications presented additional challenges by potentially increasing exposure to COVID-19 through repeated inpatient admissions to hospital during the pandemic. We report four cases for which skin flaps, lymph ligation, and split-thickness skin graft (STSG) were successfully used in the treatment of complications in the trunk and extremities after wide local excision (WLE). This study details the operative experience in management of postsurgical complications for melanoma in the trunk and extremities during a 6-month period at the height of the COVID-19 pandemic. CASE PRESENTATION: We present 4 cases detailing management of complications that occurred after wide local excisions performed for melanoma during Feb. to Oct. 2020. Case 1: A 90-year-old man who experienced wound dehiscence and necrosis on the shoulder after non-radical excision for an aggressive melanoma and underwent the side-to-side closure after ellipse formed WLE with modified tangent-to-circle method. Case 2: An 80-year-old man who had undergone excision for melanoma in his left upper arm and histopathology did not show radically. Two weeks after the excision, he underwent a WLE and direct reconstruction with double rotation skin flap. Case 3: A 55-year-old man that experienced a large wound dehiscence on his back due to WLE. He underwent an advanced double skin flap operation. Case 4: A 36-year-old woman who had a lymphorrhea and graft necrosis after WLE and STSG on the right lower leg. A combination of micro lymph ligation and re-STSG was performed. One month after the operation, all wounds had healed. There was no clinical evidence of tumor recurrence after 8 months post procedure. CONCLUSIONS: Severe complications (e.g., large wound dehiscence, necrosis, or lymphorrhea) following wide local excision of melanoma are infrequent but must be swiftly and appropriately managed, especially during the COVID-19 pandemic to decrease the likelihood of COVID-19 infection and impaired oncology outcomes from delaying systemic cancer therapy due to the complications in primary interventions.

MYCN Amplification Is Associated with Reduced Expression of Genes Encoding γ-Secretase Complex and NOTCH Signaling Components in Neuroblastoma.

Amplification of the MYCN oncogene is found in ~20% of neuroblastoma (NB) cases and correlates with high-risk disease and poor prognosis. Despite the plethora of studies describing the role of MYCN in NB, the exact molecular mechanisms underlying MYCN's contribution to high-risk disease are not completely understood. Herein, we implemented an integrative approach combining publicly available RNA-Seq and MYCN ChIP-Seq datasets derived from human NB cell lines to define biological processes directly regulated by MYCN in NB. Our approach revealed that MYCN-amplified NB cell lines, when compared to non-MYCN-amplified cell lines, are characterized by reduced expression of genes involved in NOTCH receptor processing, axoneme assembly, and membrane protein proteolysis. More specifically, we found genes encoding members of the γ-secretase complex, which is known for its ability to liberate several intracellular signaling molecules from membrane-bound proteins such as NOTCH receptors, to be down-regulated in MYCN-amplified NB cell lines. Analysis of MYCN ChIP-Seq data revealed an enrichment of MYCN binding at the transcription start sites of genes encoding γ-secretase complex subunits. Notably, using publicly available gene expression data from NB primary tumors, we revealed that the expression of γ-secretase subunits encoding genes and other components of the NOTCH signaling pathway was also reduced in MYCN-amplified tumors and correlated with worse overall survival in NB patients. Genetic or pharmacological depletion of MYCN in NB cell lines induced the expression of γ-secretase genes and NOTCH-target genes. Chemical inhibition of γ-secretase activity dampened the expression of NOTCH-target genes upon MYCN depletion in NB cells. In conclusion, this study defines a set of MYCN-regulated pathways that are specific to MYCN-amplified NB tumors, and it suggests a novel role for MYCN in the suppression of genes of the γ-secretase complex, with an impact on the NOTCH-target gene expression in MYCN-amplified NB.

The optimized quantum dot mediated thermometry reveals isoform specific differences in efficiency of myosin extracted from muscle mini bundles.

The biophysical function of myosin in vitro has been extensively investigated in different motility assays, but the study of myosin ATPase properties at the fiber level is insufficiently investigated. In this study, quantum dot (QD) mediated thermometry measurements were optimized to measure the efficiency of myosin extracted from muscle mini bundles. A reduction in fluorescent intensity of QD reflects an increase in temperature caused by the heat released during ATP hydrolysis and denotes the efficiency of the motor protein myosin. The procedure for extracting myosin was similar to the single fiber in vitro motility assay with some small modifications, and the concentration of myosin was represented by the extracted total protein since the ratio of extracted myosin to total protein was constant. Moreover, the efficiencies of myosin extracted from preparations containing different myosin heavy chain isoforms reveal lower efficiency of slow compared to fast myosin isoforms. Specifically, more heat was released in slow myosin enzymatic reaction, resulting in faster decay of QD fluorescence intensity. Hence, the optimized QD mediated thermometry provides a novel and sensitive approach to evaluate efficiency of myosin ATPase obtained from small muscle samples, representing a significant advantage in the clinical evaluation of neuromuscular disorders.

Biology of Activating Transcription Factor 4 (ATF4) and Its Role in Skeletal Muscle Atrophy.

Activating transcription factor 4 (ATF4) is a multifunctional transcription regulatory protein in the basic leucine zipper superfamily. ATF4 can be expressed in most if not all mammalian cell types, and it can participate in a variety of cellular responses to specific environmental stresses, intracellular derangements, or growth factors. Because ATF4 is involved in a wide range of biological processes, its roles in human health and disease are not yet fully understood. Much of our current knowledge about ATF4 comes from investigations in cultured cell models, where ATF4 was originally characterized and where further investigations continue to provide new insights. ATF4 is also an increasingly prominent topic of in vivo investigations in fully differentiated mammalian cell types, where our current understanding of ATF4 is less complete. Here, we review some important high-level concepts and questions concerning the basic biology of ATF4. We then discuss current knowledge and emerging questions about the in vivo role of ATF4 in one fully differentiated cell type, mammalian skeletal muscle fibers.

JAK/STAT inhibition augments soleus muscle function in a rat model of critical illness myopathy via regulation of complement C3/3R.

KEY POINTS: Critical illness myopathy (CIM) is a frequently observed negative consequence of modern critical care. Chronic Janus kinase (JAK)/signal transducer and activator of transcription activation impairs muscle size and function and is prominent following mechanical ventilation. We identify pSTAT-3 activation in tibialis anterior of CIM patients, before examining the potential benefits of JAK1/2 inhibition in an experimental model of CIM, where muscle mass and function are impaired. CIM activates complement cascade and increased monocyte infiltration in the soleus muscle, which was ameliorated by JAK1/2 inhibition, leading to reduced muscle degeneration and improved muscle force. Here, we demonstrate that JAK1/2 inhibition augments CIM muscle function through regulation of the complement cascade. ABSTRACT: Critical illness myopathy (CIM) is frequently observed in response to modern critical care with negative consequences for patient quality of life, morbidity, mortality and healthcare costs. Janus kinase (JAK)/signal transducer and activator of transcription (STAT) activation is observed in limb muscles following controlled mechanical ventilation. Chronic JAK/STAT activation promotes loss of muscle mass and function. Thus, we hypothesized that JAK1/2 inhibition would improve muscle outcomes for CIM. Following 12 days of intensive care unit conditions, pSTAT-3 levels increased in tibialis anterior muscle of CIM patients (P = 0.0489). The potential of JAK1/2 inhibition was assessed in an experimental model of CIM, where soleus muscle size and force are impaired. JAK1/2 inhibition restores soleus force (P < 0.0001). CIM activated muscle complement cascade, which was ameliorated by JAK1/2 inhibition (P < 0.05, respectively). Soleus macrophage number corresponded with complement activity, leading to reduced muscle degeneration and augmented muscle function (P < 0.05). Thus, JAK/STAT inhibition improves soleus function by modulating the complement cascade and muscle monocyte infiltration. Collectively, we demonstrate that JAK/STAT inhibition augments muscle function in CIM.

Pancreatic cancer cachexia: three dimensions of a complex syndrome.

Cancer cachexia is a multifactorial syndrome that is characterised by a loss of skeletal muscle mass, is commonly associated with adipose tissue wasting and malaise, and responds poorly to therapeutic interventions. Although cachexia can affect patients who are severely ill with various malignant or non-malignant conditions, it is particularly common among patients with pancreatic cancer. Pancreatic cancer often leads to the development of cachexia through a combination of distinct factors, which, together, explain its high prevalence and clinical importance in this disease: systemic factors, including metabolic changes and pathogenic signals related to the tumour biology of pancreatic adenocarcinoma; factors resulting from the disruption of the digestive and endocrine functions of the pancreas; and factors related to the close anatomical and functional connection of the pancreas with the gut. In this review, we conceptualise the various insights into the mechanisms underlying pancreatic cancer cachexia according to these three dimensions to expose its particular complexity and the challenges that face clinicians in trying to devise therapeutic interventions.

The novel low molecular weight MYC antagonist MYCMI-6 inhibits proliferation and induces apoptosis in breast cancer cells.

Background The MYC oncogene is one of the most frequently altered driver genes in cancer. MYC is thus a potential target for cancer treatment as well as a biomarker for the disease. However, as a target for treatment, MYC has traditionally been regarded as "undruggable" or difficult to target. We set out to evaluate the efficacy of a novel MYC inhibitor known as MYCMI-6, which acts by preventing MYC from interacting with its cognate partner MAX. Methods MYCMI-6 response was assessed in a panel of breast cancer cell lines using MTT assays and flow cytometry. MYC gene amplification, mRNA and protein expression was analysed using the TCGA and METABRIC databases. Results MYCMI-6 inhibited cell growth in breast cancer cell lines with IC50 values varying form 0.3 µM to >10 µM. Consistent with its ability to decrease cell growth, MYCMI-6 was found to induce apoptosis in two cell lines in which growth was inhibited but not in two cell lines that were resistant to growth inhibition. Across all breast cancers, MYC was found to be amplified in 15.3% of cases in the TCGA database and 26% in the METABRIC database. Following classification of the breast cancers by their molecular subtypes, MYC was most frequently amplified and exhibited highest expression at both mRNA and protein level in the basal subtype. Conclusions Based on these findings, we conclude that for patients with breast cancer, anti-MYC therapy is likely to be most efficacious in patients with the basal subtype.

A Proteomic Approach to Identify Alterations in the Small Ubiquitin-like Modifier (SUMO) Network during Controlled Mechanical Ventilation in Rat Diaphragm Muscle.

The small ubiquitin-like modifier (SUMO) is as a regulator of many cellular functions by reversible conjugation to a broad number of substrates. Under endogenous or exogenous perturbations, the SUMO network becomes a fine sensor of stress conditions by alterations in the expression level of SUMO enzymes and consequently changing the status of SUMOylated proteins. The diaphragm is the major inspiratory muscle, which is continuously active under physiological conditions, but its structure and function is severely affected when passively displaced for long extents during mechanical ventilation (MV). An iatrogenic condition called Ventilator-Induced Diaphragm Dysfunction (VIDD) is a major cause of failure to wean patients from ventilator support but the molecular mechanisms underlying this dysfunction are not fully understood. Using a unique experimental Intensive Care Unit (ICU) rat model allowing long-term MV, diaphragm muscles were collected in rats control and exposed to controlled MV (CMV) for durations varying between 1 and 10 days. Endogenous SUMOylated diaphragm proteins were identified by mass spectrometry and validated with in vitro SUMOylation systems. Contractile, calcium regulator and mitochondrial proteins were of specific interest due to their putative involvement in VIDD. Differences were observed in the abundance of SUMOylated proteins between glycolytic and oxidative muscle fibers in control animals and high levels of SUMOylated proteins were present in all fibers during CMV. Finally, previously reported VIDD biomarkers and therapeutic targets were also identified in our datasets which may play an important role in response to muscle weakness seen in ICU patients. Data are available via ProteomeXchange with identifier PXD006085. Username: reviewer26663@ebi.ac.uk, Password: rwcP5W0o.

Towards an absolute scale for adhesion strength of ship hull microfouling.

In-water ships' hull cleaning enables significant fuel savings through removal of marine fouling from surfaces. However, cleaning may also shorten the lifetime of hull coatings, with a subsequent increase in the colonization and growth rate of fouling organisms. Deleterious effects of cleaning would be minimized by matching cleaning forces to the adhesion strength of the early stages of fouling, or microfouling. Calibrated waterjets are routinely used to compare different coatings in terms of the adhesion strength of microfouling. However, an absolute scale is lacking for translating such results into cleaning forces, which are of interest for the design and operation of hull cleaning devices. This paper discusses how such forces can be determined using computational fluid dynamics. Semi-empirical formulae are derived for forces under immersed waterjets, where the normal and tangential components of wall forces are given as functions of different flow parameters. Nozzle translation speed is identified as a parameter for future research, as this may affect cleaning efficacy.

Nanothermometry Reveals Calcium-Induced Remodeling of Myosin.

Ions greatly influence protein structure-function and are critical to health and disease. A 10, 000-fold higher calcium in the sarcoplasmic reticulum (SR) of muscle suggests elevated calcium levels near active calcium channels at the SR membrane and the impact of localized high calcium on the structure-function of the motor protein myosin. In the current study, combined quantum dot (QD)-based nanothermometry and circular dichroism (CD) spectroscopy enabled detection of previously unknown enthalpy changes and associated structural remodeling of myosin, impacting its function following exposure to elevated calcium. Cadmium telluride QDs adhere to myosin, function as thermal sensors, and reveal that exposure of myosin to calcium is exothermic, resulting in lowering of enthalpy, a decrease in alpha helical content measured using CD spectroscopy, and the consequent increase in motor efficiency. Isolated muscle fibers subjected to elevated levels of calcium further demonstrate fiber lengthening and decreased motility of actin filaments on myosin-functionalized substrates. Our results, in addition to providing new insights into our understanding of muscle structure-function, establish a novel approach to understand the enthalpy of protein-ion interactions and the accompanying structural changes that may occur within the protein molecule.

Audio-video recording during laparoscopic surgery reduces irrelevant conversation between surgeons: a cohort study.

BACKGROUND: The prevalence of perioperative surgical complications is a worldwide issue: In many cases, these events are preventable. Audio-video recording during laparoscopic surgery provides useful information for the purposes of education and event analyses, and may have an impact on the focus of the surgeons operating. The aim of the present study was to investigate how audio-video recording in the operating room during laparoscopic surgery affects the focus of the surgeon and his/her assistant. METHODS: A group of laparoscopic procedures where video recording only was performed was compared to a group where both audio and video recordings were made. All laparoscopic procedures were performed at Lindesberg Hospital, Sweden, during the period August to September 2017. The primary outcome was conversation not relevant to the ongoing procedure. Secondary outcomes were intra- and postoperative adverse events or complications, operation time and number of times the assistant was corrected by the surgeon. RESULTS: The study included 41 procedures, 20 in the video only group and 21 in the audio-video group. The material comprised laparoscopic cholecystectomies, totally extraperitoneal inguinal hernia repairs and bariatric surgical procedures. Irrelevant conversation time fell from 4.2% of surgical time to 1.4% when both audio and video recordings were made (p = 0.002). No differences in perioperative adverse event or complication rates were seen. CONCLUSION: Audio-video recording during laparoscopic abdominal surgery reduces irrelevant conversation time and may improve intraoperative safety and surgical outcome. TRIAL REGISTRATION: Available at FOU Sweden (ID: 232771) and retrospectively at Clinical trials.gov (ID: NCT03425175 ; date of registration 7/2 2018).

Mechano-signalling pathways in an experimental intensive critical illness myopathy model.

KEY POINTS: Using an experimental rat intensive care unit (ICU) model, not limited by early mortality, we have previously shown that passive mechanical loading attenuates the loss of muscle mass and force-generation capacity associated with the ICU intervention. Mitochondrial dynamics have recently been shown to play a more important role in muscle atrophy than previously recognized. In this study we demonstrate that mitochondrial dynamics, as well as mitophagy, is affected by mechanosensing at the transcriptional level, and muscle changes induced by unloading are counteracted by passive mechanical loading. The recently discovered ubiquitin ligases Fbxo31 and SMART are induced by mechanical silencing, an induction that similarly is prevented by passive mechanical loading. ABSTRACT: The complete loss of mechanical stimuli of skeletal muscles, i.e. loss of external strain related to weight bearing and internal strain related to activation of contractile proteins, in mechanically ventilated, deeply sedated and/or pharmacologically paralysed intensive care unit (ICU) patients is an important factor triggering the critical illness myopathy (CIM). Using a unique experimental ICU rat model, mimicking basic ICU conditions, we have recently shown that mechanical silencing is a dominant factor triggering the preferential loss of myosin, muscle atrophy and decreased specific force in fast- and slow-twitch muscles and muscle fibres. The aim of this study is to gain improved understanding of the gene signature and molecular pathways regulating the process of mechanical activation of skeletal muscle that are affected by the ICU condition. We have focused on pathways controlling myofibrillar protein synthesis and degradation, mitochondrial homeostasis and apoptosis. We demonstrate that genes regulating mitochondrial dynamics, as well as mitophagy are induced by mechanical silencing and that these effects are counteracted by passive mechanical loading. In addition, the recently identified ubiquitin ligases Fbxo31 and SMART are induced by mechanical silencing, an induction that is reversed by passive mechanical loading. Thus, mechano-cell signalling events are identified which may play an important role for the improved clinical outcomes reported in response to the early mobilization and physical therapy in immobilized ICU patients.

Comprehensive analysis of tropomyosin isoforms in skeletal muscles by top-down proteomics.

Mammalian skeletal muscles are heterogeneous in nature and are capable of performing various functions. Tropomyosin (Tpm) is a major component of the thin filament in skeletal muscles and plays an important role in controlling muscle contraction and relaxation. Tpm is known to consist of multiple isoforms resulting from different encoding genes and alternative splicing, along with post-translational modifications. However, a systematic characterization of Tpm isoforms in skeletal muscles is still lacking. Therefore, we employed top-down mass spectrometry (MS) to identify and characterize Tpm isoforms present in different skeletal muscles from multiple species, including swine, rat, and human. Our study revealed that Tpm1.1 and Tpm2.2 are the two major Tpm isoforms in swine and rat skeletal muscles, whereas Tpm1.1, Tpm2.2, and Tpm3.12 are present in human skeletal muscles. Tandem MS was utilized to identify the sequences of the major Tpm isoforms. Furthermore, quantitative analysis revealed muscle-type specific differences in the abundance of un-modified and modified Tpm isoforms in rat and human skeletal muscles. This study represents the first systematic investigation of Tpm isoforms in skeletal muscles, which not only demonstrates the capabilities of top-down MS for the comprehensive characterization of skeletal myofilament proteins but also provides the basis for further studies on these Tpm isoforms in muscle-related diseases.

Impaired Ca(2+) release contributes to muscle weakness in a rat model of critical illness myopathy.

BACKGROUND: Critical illness myopathy is an acquired skeletal muscle disorder with severe myosin loss and muscle weakness frequently seen in intensive care unit (ICU) patients. It is unknown if impaired excitation-contraction coupling contributes to the muscle weakness. METHODS: We used a unique ICU model where rats were deeply sedated, post-synaptically pharmacologically paralyzed, mechanically ventilated and closely monitored for up to ten days. Single intact fibers from the flexor digitorum brevis muscle were isolated and used to measure force and free myoplasmic [Ca(2+)] ([Ca(2+)]i) during tetanic contractions. RESULTS: Fibers from ICU rats had 80 % lower tetanic [Ca(2+)]i and produced only 15 % of the force seen in fibers from sham-operated (SHAM) rats. In the presence of 5 mM caffeine, tetanic [Ca(2+)]i was similar in fibers from ICU and SHAM rats but force was 50 % lower in fibers from ICU rats than SHAM rats. Confocal imaging showed disrupted tetanic [Ca(2+)]i transients in fibers from ICU rats compared to SHAM rats. Western blots showed similar levels of Na(+) channel and dihydropyridine receptor (DHPR) protein expression, whereas ryanodine receptor (RyR) and sarco-endoplasmic reticulum Ca(2+) ATPase 1 (SERCA1) expression was markedly lower in muscle of ICU rats than in SHAM rats. Immunohistochemical analysis showed that distribution of Na(+) channel and DHPR protein on the sarcolemma was disrupted in fibers from ICU rats compared with SHAM rats. CONCLUSIONS: These results suggest that impaired SR Ca(2+) release contributes to the muscle weakness seen in patients in ICU.

Optimization of exposure in panoramic radiography while maintaining image quality using adaptive filtering.

Objective The purpose of the present study was to investigate the potential of using advanced external adaptive image processing for maintaining image quality while reducing exposure in dental panoramic storage phosphor plate (SPP) radiography. Materials and methods Thirty-seven SPP radiographs of a skull phantom were acquired using a Scanora panoramic X-ray machine with various tube load, tube voltage, SPP sensitivity and filtration settings. The radiographs were processed using General Operator Processor (GOP) technology. Fifteen dentists, all within the dental radiology field, compared the structural image quality of each radiograph with a reference image on a 5-point rating scale in a visual grading characteristics (VGC) study. The reference image was acquired with the acquisition parameters commonly used in daily operation (70 kVp, 150 mAs and sensitivity class 200) and processed using the standard process parameters supplied by the modality vendor. Results All GOP-processed images with similar (or higher) dose as the reference image resulted in higher image quality than the reference. All GOP-processed images with similar image quality as the reference image were acquired at a lower dose than the reference. This indicates that the external image processing improved the image quality compared with the standard processing. Regarding acquisition parameters, no strong dependency of the image quality on the radiation quality was seen and the image quality was mainly affected by the dose. Conclusions The present study indicates that advanced external adaptive image processing may be beneficial in panoramic radiography for increasing the image quality of SPP radiographs or for reducing the exposure while maintaining image quality.

Sin3b interacts with Myc and decreases Myc levels.

Myc expression is deregulated in many human cancers. A yeast two-hybrid screen has revealed that the transcriptional repressor Sin3b interacts with Myc protein. Endogenous Myc and Sin3b co-localize and interact in the nuclei of human and rat cells, as assessed by co-immunoprecipitation, immunofluorescence, and proximity ligation assay. The interaction is Max-independent. A conserved Myc region (amino acids 186-203) is required for the interaction with Sin3 proteins. Histone deacetylase 1 is recruited to Myc-Sin3b complexes, and its deacetylase activity is required for the effects of Sin3b on Myc. Myc and Sin3a/b co-occupied many sites on the chromatin of human leukemia cells, although the presence of Sin3 was not associated with gene down-regulation. In leukemia cells and fibroblasts, Sin3b silencing led to Myc up-regulation, whereas Sin3b overexpression induced Myc deacetylation and degradation. An analysis of Sin3b expression in breast tumors revealed an association between low Sin3b expression and disease progression. The data suggest that Sin3b decreases Myc protein levels upon Myc deacetylation. As Sin3b is also required for transcriptional repression by Mxd-Max complexes, our results suggest that, at least in some cell types, Sin3b limits Myc activity through two complementary activities: Mxd-dependent gene repression and reduction of Myc levels.

Effective top-down LC/MS+ method for assessing actin isoforms as a potential cardiac disease marker.

Actin is the major component of the cytoskeleton, playing an essential role in the structure and motility of both muscle and nonmuscle cells. It is highly conserved and encoded by a multigene family. α-Cardiac actin (αCAA) and α-skeletal actin (αSKA), encoded by two different genes, are the primary actin isoforms expressed in striated muscles. The relative expression levels of αSKA and αCAA have been shown to vary between species and under pathological conditions. In particular, an increased αSKA expression is believed to be a programmed response of a diseased heart. Therefore, it is essential to quantify the relative expression of αSKA and αCAA, which remains challenging due to the high degree of sequence similarity between these isoforms (98.9%). Herein, we developed a top-down liquid chromatography/mass spectrometry-based ("LC/MS+") method for the rapid purification and comprehensive analysis of α-actin extracted from muscle tissues. We thoroughly investigated all of the actin isoforms in healthy human cardiac and skeletal muscles. We found that αSKA is the only isoform expressed in skeletal muscle, whereas αCAA and αSKA are coexpressed in cardiac muscle. We then applied our method to quantify the α-actin isoforms in human healthy hearts and failing hearts with dilated cardiomyopathy (DCM). We found that αSKA is augmented in DCM compared with healthy controls, 43.1 ± 0.9% versus 23.7 ± 1.7%, respectively. As demonstrated, top-down LC/MS+ provides an effective and comprehensive method for the purification, quantification, and characterization of α-actin isoforms, enabling assessment of their clinical potential as cardiac disease markers.

Clinical and inflammatory characteristics of the European U-BIOPRED adult severe asthma cohort.

U-BIOPRED is a European Union consortium of 20 academic institutions, 11 pharmaceutical companies and six patient organisations with the objective of improving the understanding of asthma disease mechanisms using a systems biology approach.This cross-sectional assessment of adults with severe asthma, mild/moderate asthma and healthy controls from 11 European countries consisted of analyses of patient-reported outcomes, lung function, blood and airway inflammatory measurements.Patients with severe asthma (nonsmokers, n=311; smokers/ex-smokers, n=110) had more symptoms and exacerbations compared to patients with mild/moderate disease (n=88) (2.5 exacerbations versus 0.4 in the preceding 12 months; p<0.001), with worse quality of life, and higher levels of anxiety and depression. They also had a higher incidence of nasal polyps and gastro-oesophageal reflux with lower lung function. Sputum eosinophil count was higher in severe asthma compared to mild/moderate asthma (median count 2.99% versus 1.05%; p=0.004) despite treatment with higher doses of inhaled and/or oral corticosteroids.Consistent with other severe asthma cohorts, U-BIOPRED is characterised by poor symptom control, increased comorbidity and airway inflammation, despite high levels of treatment. It is well suited to identify asthma phenotypes using the array of "omic" datasets that are at the core of this systems medicine approach.