oxidative stress and the diaphragm

Oxygen deficit (hypoxia) is a major feature of cardiorespiratory diseases characterized by diaphragm dysfunction, yet the putative role of hypoxic stress as a driver of diaphragm dysfunction is understudied. We explored the cellular and functional consequences of sustained hypoxic stress in a mouse model. Adult male mice were exposed to 8 hours of normoxia, or hypoxia (FiO2  = 0.10) with or without antioxidant pretreatment (N-acetyl cysteine, 200 mg/kg i.p.). Ventilation and metabolism were measured. Diaphragm muscle contractile function, myofibre size and distribution, gene expression, protein signalling cascades, and oxidative stress (TBARS) were determined...

Objective This study aimed to examine the mechanism of diaphragmatic dysfunction in sepsis due to severe acute pancreatitis (SAP) with intra-abdominal hypertension (IAH) in a rat model. Methods The rats were assigned at random to four groups: (1) control (n = 5), (2) SAP (n = 5), (3) SAP+IAH (n = 5), and (4) SAP+IAH+SS-31 (n = 5). Length and force output of the diaphragm were analysed in vivo. Histopathological examinations were performed by haematoxylin-eosin. Oxidative stress levels related to protease in diaphragmatic mitochondria were detected with a colorimetric technique...

BACKGROUND: Anesthetics in ventilated patients are critical as any cofactor hampering diaphragmatic function may have a negative impact on the weaning progress and therefore on patients' mortality. Dexmedetomidine may display antioxidant and antiproteolytic properties, but it also reduced glucose uptake by the muscle, which may impair diaphragm force production. This study tested the hypothesis that dexmedetomidine could inhibit ventilator-induced diaphragmatic dysfunction. METHODS: Twenty-four rats were separated into three groups (n = 8/group)...

Our recent study demonstrated that acetylcholinesterase (AChE) activity at the neuromuscular junction (NMJ) of the diaphragm decreased during sepsis. However, the mechanisms were not clearly identified. In this study, we aimed to investigate whether the decreased AChE activity was related to oxidative stress by observing AChE activity in different grades of sepsis induced by caecal ligation and puncture (CLP). At 24 h after surgery, an assay of thiobarbituric acid reactive species (TBARS) and protein carbonyls, as well as the myeloperoxidase (MPO), superoxide dismutase (SOD), and catalase (CAT) activity, was conducted...

The preterm diaphragm is functionally immature compared to its term counterpart. In utero inflammation further exacerbates preterm diaphragm dysfunction. We hypothesized that preterm lambs are more vulnerable to in utero inflammation induced diaphragm dysfunction compared with term lambs. Pregnant ewes received intra-amniotic (IA) injections of saline or 10mg lipopolysaccharide (LPS) 2d or 7d prior to delivery at 121d (preterm) or 145d (term) gestation. Diaphragm contractile function was assessed in vitro. Plasma cytokines and diaphragm myosin heavy chain (MHC) isoforms and oxidative stress were evaluated...

Duchenne muscular dystrophy (DMD) is characterized by striated muscle weakness, cardiomyopathy, and respiratory failure. Since oxidative stress is recognized as a secondary pathology in DMD, the efficacy of antioxidant intervention, using the superoxide scavenger tempol, was examined on functional and biochemical status of dystrophin-deficient diaphragm muscle. Diaphragm muscle function was assessed, ex vivo, in adult male wild-type and dystrophin-deficient mdx mice, with and without a 14-day antioxidant intervention...

Recurrent and massive intravascular haemolysis induces proteinuria, glomerulosclerosis, and progressive impairment of renal function, suggesting podocyte injury. However, the effects of haemoglobin (Hb) on podocytes remain unexplored. Our results show that cultured human podocytes or podocytes isolated from murine glomeruli bound and endocytosed Hb through the megalin-cubilin receptor system, thus resulting in increased intracellular Hb catabolism, oxidative stress, activation of the intrinsic apoptosis pathway, and altered podocyte morphology, with decreased expression of the slit diaphragm proteins nephrin and synaptopodin...

Mechanical ventilation (MV) results in the rapid development of ventilator-induced diaphragm dysfunction (VIDD). While the mechanisms responsible for VIDD are not fully understood, recent data reveal that prolonged MV activates autophagy in the diaphragm, which may occur as a result of increased cellular reactive oxygen species (ROS) production. Therefore, we tested the hypothesis that (1) accelerated autophagy is a key contributor to VIDD; and that (2) oxidative stress is required to increase the expression of autophagy genes in the diaphragm...

Prolonged use of mechanical ventilation (MV) leads to atrophy and dysfunction of the major inspiratory muscle, the diaphragm, contributing to ventilator dependence. Numerous studies have shown that proteolysis and oxidative stress are among the major effectors of ventilator-induced diaphragm muscle dysfunction (VIDD), but the upstream initiator(s) of this process remain to be elucidated. We report here that periodic diaphragm contraction via phrenic nerve stimulation (PNS) substantially reduces MV-induced proteolytic activity and oxidative stress in the diaphragm...

BACKGROUND & AIMS: Duchenne muscular dystrophy (DMD) is characterized by the absence of dystrophin and muscle degeneration. Calcium dysregulation and oxidative stress also contribute to the disease progression. We evaluated the potential therapeutic benefits of supplementation with omega-3 on the metabolic profile, calcium-related proteins and oxidative stress response in the heart and diaphragm (DIA) of the mdx mouse model of DMD at later stages of the disease (13 months). METHODS: Mdx mice (8 months old) received omega-3 via a dietary supplement for 5 months...

OBJECTIVE: Oxidative stress, in addition to the absence of the dystrophin protein, has been considered an important regulator of Duchenne muscular dystrophy (DMD). Vitamin E presents an important role as a potent antioxidant and in preserving the integrity of the cell membrane. In this study, we evaluated the effects of vitamin E therapy on some physiological pathways that can contribute to muscle injury in the diaphragm muscle of mdx mice (the experimental model of DMD) such as CK levels, inflammatory response, oxidative stress, and the enzymatic antioxidant system...

Undesirable exposure of diaphragm to radiation during thoracic radiation therapy has not been fully considered over the past decades. Our study aims to examine the potential biological effects on diaphragm induced by radiation. One-time ionizing irradiation of 10 Gy was applied either to the diaphragmatic region of mice or to the cultured C2C12 myocytes. Each sample was then assayed for muscle function, oxidative stress, or cell viability on days 1, 3, 5, and 7 after irradiation. Our mouse model shows that radiation significantly reduced muscle function on the 5th and 7th days and increased reactive oxygen species (ROS) formation in the diaphragm tissue from days 3 to 7...

Film bulk acoustic resonators (FBARs) are widely applied in mass bio-sensing and pressure sensors, owing to their extreme sensitivity and integration ability, and ability to miniaturize circuits. A volatile organic compound (VOC) sensor with a polymer-coated diaphragm, using FBARs as a strain sensing element is proposed and optimized. This vapor sensor is based on organic vapor-induced changes of mechanical deformation of the micro-diaphragm. The four FBARs are located at the edge of the bi-layer diaphragm comprising silicon nitride and silicon oxide for strain extraction...

BACKGROUND/AIMS: Diabetic nephropathy (DN) is a microangiopathic disease characterized by excessive urinary albumin excretion, which occurs in 30% of patients with diabetes mellitus. It is the second leading cause of end-stage renal diseases in China. Nuclear factor-kappa B (NF-κB) is reported to be closely correlated with the inflammation underlying diabetes-associated renal damage. Crocin, a plant-derived compound, has antioxidant properties that may inhibit NF-κB. METHODS: In the present study, we used a conditionally immortalized mouse podocyte cell line to explore whether crocin could effectively block albuminuria...

Clinical studies have identified patients with nephrotic syndrome caused by mutations in genes involved in the biosynthesis of coenzyme Q10 (CoQ10), a lipid component of the mitochondrial electron transport chain and an important antioxidant. However, the cellular mechanisms through which these mutations induce podocyte injury remain obscure. Here, we exploited the striking similarities between Drosophila nephrocytes and human podocytes to develop a Drosophila model of these renal diseases, and performed a systematic in vivo analysis assessing the role of CoQ10 pathway genes in renal function...

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)...

AIM: This study aimed to evaluate the molecular mechanism mitigating progress of chronic nephropathy by mesenchymal stem cells. METHODS: Rats were divided into normal control (Normal), ADR + vehicle (CON), and ADR + MSC (MSC) groups. Nephropathy was induced by ADR (4 mg/kg) and MSCs (2 × 10(6) ) were injected. Rats were sacrificed 1 or 6 weeks after ADR injection. NF-kB, MAPKs, inflammation, oxidative stress, profibrotic molecules, and nephrin expression were evaluated...

Chronic kidney disease (CKD) is characterized by an irreversible decrease in kidney function and induction of various metabolic dysfunctions. Accumulated findings reveal that chronic hypoxic stress and endoplasmic reticulum (ER) stress are involved in a range of pathogenic conditions, including the progression of CKD. Because of the presence of an arteriovenous oxygen shunt, the kidney is thought to be susceptible to hypoxia. Chronic kidney hypoxia is induced by a number of pathogenic conditions, including renal ischemia, reduced peritubular capillary, and tubulointerstitial fibrosis...

Strategies to treat cachexia are still at its infancy. Enhanced muscle protein breakdown and ubiquitin-proteasome system are common features of cachexia associated with chronic conditions including lung cancer (LC). Poly(ADP-ribose) polymerases (PARP), which play a major role in chromatin structure regulation, also underlie maintenance of muscle metabolism and body composition. We hypothesized that protein catabolism, proteolytic markers, muscle fiber phenotype, and muscle anabolism may improve in respiratory and limb muscles of LC-cachectic Parp-1-deficient (Parp-1(-/-) ) and Parp-2(-/-) mice...

Patients with pulmonary hypertension (PH) suffer from inspiratory insufficiency, which has been associated with intrinsic contractile dysfunction in diaphragm muscle. Here, we examined the role of redox stress in PH-induced diaphragm weakness by using the novel antioxidant, EUK-134. Male Wistar rats were randomly divided into control (CNT), CNT + EUK-134 (CNT + EUK), monocrotaline-induced PH (PH), and PH + EUK groups. PH was induced by a single intraperitoneal injection of monocrotaline (60 mg/kg body weight)...