275 research outputs found

    Calpain 3 and CaMKIIβ signaling are required to induce HSP70 necessary for adaptive muscle growth after atrophy.

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    Mutations in CAPN3 cause autosomal recessive limb girdle muscular dystrophy 2A. Calpain 3 (CAPN3) is a calcium dependent protease residing in the myofibrillar, cytosolic and triad fractions of skeletal muscle. At the triad, it colocalizes with calcium calmodulin kinase IIβ (CaMKIIβ). CAPN3 knock out mice (C3KO) show reduced triad integrity and blunted CaMKIIβ signaling, which correlates with impaired transcriptional activation of myofibrillar and oxidative metabolism genes in response to running exercise. These data suggest a role for CAPN3 and CaMKIIβ in gene regulation that takes place during adaptation to endurance exercise. To assess whether CAPN3- CaMKIIβ signaling influences skeletal muscle remodeling in other contexts, we subjected C3KO and wild type mice to hindlimb unloading and reloading and assessed CaMKIIβ signaling and gene expression by RNA-sequencing. After induced atrophy followed by 4 days of reloading, both CaMKIIβ activation and expression of inflammatory and cellular stress genes were increased. C3KO muscles failed to activate CaMKIIβ signaling, did not activate the same pattern of gene expression and demonstrated impaired growth at 4 days of reloading. Moreover, C3KO muscles failed to activate inducible HSP70, which was previously shown to be indispensible for the inflammatory response needed to promote muscle recovery. Likewise, C3KO showed diminished immune cell infiltration and decreased expression of pro-myogenic genes. These data support a role for CaMKIIβ signaling in induction of HSP70 and promotion of the inflammatory response during muscle growth and remodeling that occurs after atrophy, suggesting that CaMKIIβ regulates remodeling in multiple contexts: endurance exercise and growth after atrophy

    A nitric oxide synthase transgene ameliorates muscular dystrophy in mdx mice

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    Dystrophin-deficient muscles experience large reductions in expression of nitric oxide synthase (NOS), which suggests that NO deficiency may influence the dystrophic pathology. Because NO can function as an antiinflammatory and cytoprotective molecule, we propose that the loss of NOS from dystrophic muscle exacerbates muscle inflammation and fiber damage by inflammatory cells. Analysis of transgenic mdx mice that were null mutants for dystrophin, but expressed normal levels of NO in muscle, showed that the normalization of NO production caused large reductions in macrophage concentrations in the mdx muscle. Expression of the NOS transgene in mdx muscle also prevented the majority of muscle membrane injury that is detectable in vivo, and resulted in large decreases in serum creatine kinase concentrations. Furthermore, our data show that mdx muscle macrophages are cytolytic at concentrations that occur in dystrophic, NOS-deficient muscle, but are not cytolytic at concentrations that occur in dystrophic mice that express the NOS transgene in muscle. Finally, our data show that antibody depletions of macrophages from mdx mice cause significant reductions in muscle membrane injury. Together, these findings indicate that macrophages promote injury of dystrophin-deficient muscle, and the loss of normal levels of NO production by dystrophic muscle exacerbates inflammation and membrane injury in muscular dystrophy

    Osteopontin ablation ameliorates muscular dystrophy by shifting macrophages to a pro-regenerative phenotype.

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    In the degenerative disease Duchenne muscular dystrophy, inflammatory cells enter muscles in response to repetitive muscle damage. Immune factors are required for muscle regeneration, but chronic inflammation creates a profibrotic milieu that exacerbates disease progression. Osteopontin (OPN) is an immunomodulator highly expressed in dystrophic muscles. Ablation of OPN correlates with reduced fibrosis and improved muscle strength as well as reduced natural killer T (NKT) cell counts. Here, we demonstrate that the improved dystrophic phenotype observed with OPN ablation does not result from reductions in NKT cells. OPN ablation skews macrophage polarization toward a pro-regenerative phenotype by reducing M1 and M2a and increasing M2c subsets. These changes are associated with increased expression of pro-regenerative factors insulin-like growth factor 1, leukemia inhibitory factor, and urokinase-type plasminogen activator. Furthermore, altered macrophage polarization correlated with increases in muscle weight and muscle fiber diameter, resulting in long-term improvements in muscle strength and function in mdx mice. These findings suggest that OPN ablation promotes muscle repair via macrophage secretion of pro-myogenic growth factors

    The Special Measures for Quality and Challenged Provider Regimes in the English NHS: A Rapid Evaluation of a National Improvement Initiative for Failing Healthcare Organisations

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    BACKGROUND: There is limited knowledge about interventions used for the improvement of low-performing healthcare organisations and their unintended consequences. Our evaluation sought to understand how healthcare organisations in the National Health Service (NHS) in England responded to a national improvement initiative (the Special Measures for Quality [SMQ] and challenged provider [CP] regimes) and its perceived impact on achieving quality improvements (QIs). METHODS: Our evaluation included national-level interviews with key stakeholders involved in the delivery of SMQ (n=6); documentary analysis (n=20); and a qualitative study based on interviews (n=60), observations (n=8) and documentary analysis (n=291) in eight NHS case study sites. The analysis was informed by literature on failure, turnaround and QI in organisations in the public sector. RESULTS: At the policy level, SMQ/CP regimes were intended to be "support" programmes, but perceptions of the interventions at hospital level were mixed. The SMQ/CP regimes tended to consider failure at an organisational level and turnaround was visualised as a linear process. There was a negative emotional impact reported by staff, especially in the short-term. Key drivers of change included: engaged senior leadership teams, strong clinical input and supportive external partnerships within local health systems. Trusts focused efforts to improve across multiple domains with particular investment in improving overall staff engagement, developing an open, listening organisational culture and better governance to ensure clinical safety and reporting. CONCLUSION: Organisational improvement in healthcare requires substantial time to embed and requires investment in staff to drive change and cultivate QI capabilities at different tiers. The time this takes may be underestimated by external 'turn-around' interventions and performance regimes designed to improve quality in the short-term and which come at an emotional cost for staff. Shifting an improvement focus to the health system or regional level may promote sustainable improvement across multiple organisations over the long-term

    Osteopontin ablation ameliorates muscular dystrophy by shifting macrophages to a proregenerative phenotype

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    In the degenerative disease Duchenne muscular dystrophy, inflammatory cells enter muscles in response to repetitive muscle damage. Immune factors are required for muscle regeneration, but chronic inflammation creates a profibrotic milieu that exacerbates disease progression. Osteopontin (OPN) is an immunomodulator highly expressed in dystrophic muscles. Ablation of OPN correlates with reduced fibrosis and improved muscle strength as well as reduced natural killer T (NKT) cell counts. Here, we demonstrate that the improved dystrophic phenotype observed with OPN ablation does not result from reductions in NKT cells. OPN ablation skews macrophage polarization toward a pro-regenerative phenotype by reducing M1 and M2a and increasing M2c subsets. These changes are associated with increased expression of pro-regenerative factors insulin-like growth factor 1, leukemia inhibitory factor, and urokinase-type plasminogen activator. Furthermore, altered macrophage polarization correlated with increases in muscle weight and muscle fiber diameter, resulting in long-term improvements in muscle strength and function in mdx mice. These findings suggest that OPN ablation promotes muscle repair via macrophage secretion of pro-myogenic growth factors

    High-resolution microbiome analysis reveals exclusionary Klebsiella species competition in preterm infants at risk for necrotizing enterocolitis.

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    Intestinal colonization with Klebsiella has been linked to necrotizing enterocolitis (NEC), but methods of analysis usually failed to discriminate Klebsiella species or strains. A novel ~ 2500-base amplicon (StrainID) that spans the 16S and 23S rRNA genes was used to generate amplicon sequence variant (ASV) fingerprints for Klebsiella oxytoca and Klebsiella pneumoniae species complexes (KoSC and KpSC, respectively) and co-occurring fecal bacterial strains from 10 preterm infants with NEC and 20 matched controls. Complementary approaches were used to identify cytotoxin-producing isolates of KoSC. Klebsiella species colonized most preterm infants, were more prevalent in NEC subjects versus controls, and replaced Escherichia in NEC subjects. Single KoSC or KpSC ASV fingerprinted strains dominated the gut microbiota, suggesting exclusionary Klebsiella competition for luminal resources. Enterococcus faecalis was co-dominant with KoSC but present infrequently with KpSC. Cytotoxin-producing KoSC members were identified in most NEC subjects and were less frequent in controls. Few Klebsiella strains were shared between subjects. We conclude that inter-species Klebsiella competition, within an environment of KoSC and E. faecalis cooperation, appears to be an important factor for the development of NEC. Preterm infants seem to acquire Klebsiella primarily through routes other than patient-to-patient transmission

    Intermittent prophylactic antibiotics for bronchiectasis (Review)

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    Background: Bronchiectasis is a common but under‐diagnosed chronic disorder characterised by permanent dilation of the airways arising from a cycle of recurrent infection and inflammation. Symptoms including chronic, persistent cough and productive phlegm are a significant burden for people with bronchiectasis, and the main aim of treatment is to reduce exacerbation frequency and improve quality of life. Prophylactic antibiotic therapy aims to break this infection cycle and is recommended by clinical guidelines for adults with three or more exacerbations a year, based on limited evidence. It is important to weigh the evidence for bacterial suppression against the prevention of antibiotic resistance and further evidence is required on the safety and efficacy of different regimens of intermittently administered antibiotic treatments for people with bronchiectasis. Objectives: To evaluate the safety and efficacy of intermittent prophylactic antibiotics in the treatment of adults and children with bronchiectasis. Search methods: We identified trials from the Cochrane Airways Trials Register, which contains studies identified through multiple electronic searches and handsearches of other sources. We also searched trial registries and reference lists of primary studies. We conducted searches on 6 September 2021, with no restriction on language of publication. Selection criteria: We included randomised controlled trials (RCTs) of at least three months' duration comparing an intermittent regime of prophylactic antibiotics with placebo, usual care or an alternate intermittent regimen. Intermittent prophylactic administration was defined as repeated courses of antibiotics with on‐treatment and off‐treatment intervals of at least 14 days' duration. We included adults and children with a clinical diagnosis of bronchiectasis confirmed by high resolution computed tomography (HRCT), plain film chest radiograph, or bronchography and a documented history of recurrent chest infections. We excluded studies where participants received high dose antibiotics immediately prior to enrolment or those with a diagnosis of cystic fibrosis, allergic bronchopulmonary aspergillosis (ABPA), primary ciliary dyskinesia, hypogammaglobulinaemia, sarcoidosis, or a primary diagnosis of COPD. Our primary outcomes were exacerbation frequency and serious adverse events. We did not exclude studies on the basis of review outcomes. Data collection and analysis: We analysed dichotomous data as odds ratios (ORs) or relative risk (RRs) and continuous data as mean differences (MDs) or standardised mean differences (SMDs). We used standard methodological procedures expected by Cochrane. We conducted GRADE assessments for the following primary outcomes: exacerbation frequency; serious adverse events and secondary outcomes: antibiotic resistance; hospital admissions; health‐related quality of life. Main results: We included eight RCTs, with interventions ranging from 16 to 48 weeks, involving 2180 adults. All evaluated one of three types of antibiotics over two to six cycles of 28 days on/off treatment: aminoglycosides, ß‐lactams or fluoroquinolones. Two studies also included 12 cycles of 14 days on/off treatment with fluoroquinolones. Participants had a mean age of 63.6 years, 65% were women and approximately 85% Caucasian. Baseline FEV1 ranged from 55.5% to 62.6% predicted. None of the studies included children. Generally, there was a low risk of bias in the included studies. Antibiotic versus placebo: cycle of 14 days on/off. Ciprofloxacin reduced the frequency of exacerbations compared to placebo (RR 0.75, 95% CI 0.61 to 0.93; I2 = 65%; 2 studies, 469 participants; moderate‐certainty evidence), with eight people (95% CI 6 to 28) needed to treat for an additional beneficial outcome. The intervention increased the risk of antibiotic resistance more than twofold (OR 2.14, 95% CI 1.36 to 3.35; I2 = 0%; 2 studies, 624 participants; high‐certainty evidence). Serious adverse events, lung function (FEV1), health‐related quality of life, and adverse effects did not differ between groups. Antibiotic versus placebo: cycle of 28 days on/off. Antibiotics did not reduce overall exacerbation frequency (RR 0.92, 95% CI 0.82 to 1.02; I2 = 0%; 8 studies, 1695 participants; high‐certainty evidence) but there were fewer severe exacerbations (OR 0.59, 95% CI 0.37 to 0.93; I2 = 54%; 3 studies, 624 participants), though this should be interpreted with caution due to low event rates. The risk of antibiotic resistance was more than twofold higher based on a pooled analysis (OR 2.20, 95% CI 1.42 to 3.42; I2 = 0%; 3 studies, 685 participants; high‐certainty evidence) and consistent with unpooled data from four further studies. Serious adverse events, time to first exacerbation, duration of exacerbation, respiratory‐related hospital admissions, lung function, health‐related quality of life and adverse effects did not differ between study groups. Antibiotic versus usual care. We did not find any studies that compared intermittent antibiotic regimens with usual care. Cycle of 14 days on/off versus cycle of 28 days on/off. Exacerbation frequency did not differ between the two treatment regimens (RR 1.02, 95% CI 0.84 to 1.24; I2 = 71%; 2 studies, 625 participants; moderate‐certainty evidence) However, inconsistencies in the results from the two trials in this comparison indicate that the apparent aggregated similarities may not be reliable. There was no evidence of a difference in antibiotic resistance between groups (OR 1.00, 95% CI 0.68 to 1.48; I2 = 60%; 2 studies, 624 participants; moderate‐certainty evidence). Serious adverse events, adverse effects, lung function and health‐related quality of life did not differ between the two antibiotic regimens. Authors' conclusions: Overall, in adults who have frequent chest infections, long‐term antibiotics given at 14‐day on/off intervals slightly reduces the frequency of those infections and increases antibiotic resistance. Intermittent antibiotic regimens result in little to no difference in serious adverse events. The impact of intermittent antibiotic therapy on children with bronchiectasis is unknown due to an absence of evidence, and further research is needed to establish the potential risks and benefits
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