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Mechanical Dysfunction (mechanical + dysfunction)
Selected AbstractsDifferential regulation of the nitric oxide,cGMP pathway exacerbates postischaemic heart injury in stroke-prone hypertensive ratsEXPERIMENTAL PHYSIOLOGY, Issue 1 2007Tetsuji Itoh Using a working perfused heart model, we investigated the hypothesis that alterations in the NO,cGMP pathway may exacerbate postischaemic mechanical dysfunction in the hypertrophied heart. Ischaemia for 25 min followed by reperfusion for 30 min produced marked cardiac mechanical dysfunction in both stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar Kyoto rats (WKY). Exogenous treatment with S -nitroso- N -acetyl- dl -penicillamine (SNAP), a NO donor, had beneficial effects on the cardiac dysfunction induced by ischaemia,reperfusion (I/R) in the WKY heart, but the cardioprotective effect of SNAP was eliminated by guanylyl cyclase inhibitor. Cardiac cGMP levels were increased by SNAP or ischaemia in WKY. In contrast, in SHRSP hearts, SNAP could not alleviate the cardiac dysfunction caused by I/R. Pre-ischaemia, the cardiac cGMP level was significantly higher in SHRSP than in WKY; however, no significant difference was found after SNAP and ischaemia. The myocardial Ca2+ -dependent NO synthase (NOS) activity increased at the end of ischaemia in WKY. Conversely, the Ca2+ -independent NOS activity and protein levels were upregulated by I/R in the SHRSP myocardium. In the SHRSP hearts, non-selective NOS and selective Ca2+ -independent NOS inhibitors or antioxidant treatment alleviated cardiac dysfunction caused by I/R. Moreover, mRNA expression and Western blotting analysis of cGMP-dependent protein kinase type I showed more deterioration of SHRSP hearts compared with WKY. These results suggest that: (1) the NO-dependent cardioprotective effect is depressed; and (2) overproduction of NO derived from Ca2+ -independent NOS contributes to postischaemic heart injury in the hypertrophied heart of hypertensive status. [source] The impact of joint bleeding and synovitis on physical ability and joint function in a murine model of haemophilic synovitisHAEMOPHILIA, Issue 1 2008C. MEJIA-CARVAJAL Summary., Haemophilia is a congenital disorder that commonly results in musculoskeletal bleeding and orthopaedic complications. After an acute joint haemorrhage, an increase in intra-articular pressure and inflammation cause pain, swelling and limited motion. Blood in the joint space provokes a proliferative disorder known as haemophilic synovitis. Overgrowth of the synovial membrane causes mechanical dysfunction. Eventually, there is destruction of the articular surface and underlying bone. The aim of this project was to test the hypothesis that a minimum number of haemarthroses negatively impacts on joint function and that this would be reflected by decreased physical performance of experimental animals. Mice deficient in factor VIII coagulant activity were trained to ambulate on a rotating rod then injured three times at weekly intervals. Their ability to walk was then compared to a group of uninjured mice. Cohorts of mice were killed after 1, 2 or 3 months and the knee joints examined by gross and histological methods. The results supported the following conclusions: (i) haemophilic mice can be trained to ambulate on a rotating rod; (ii) acute hemarthrosis temporarily impairs their ability to ambulate and (iii) following recovery from acute injury, mice developing synovitis demonstrated inferior physical ability compared to mice not developing synovitis. This is the first description of a quantitative assay to monitor joint function in experimental animals and should be useful to evaluate the efficacy of new therapies developed to prevent and treat bleeding and to test strategies to counter the devastating effects of synovitis. [source] Ranolazine Attenuates Palmitoyl- l -carnitine-induced Mechanical and Metabolic Derangement in the Isolated, Perfused Rat HeartJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2000KAZUYASU MARUYAMA The effect of ranolazine, a novel anti-ischaemic drug that stimulates the activity of pyruvate dehydrogenase, on palmitoyl- l -carnitine-induced mechanical dysfunction and metabolic derangement in isolated perfused rat hearts has been studied and compared with the effect of dichloroacetate, an activator of pyruvate dehydrogenase. Rat hearts paced electrically were perfused aerobically at constant flow by the Langendorff technique. Palmitoyl- l -carnitine (4 ,m) increased left ventricular end-diastolic pressure and reduced left ventricular developed pressure (i.e. induced mechanical dysfunction); it also reduced tissue levels of adenosine triphosphate and increased tissue levels of adenosine monophosphate (i.e. induced metabolic derangement). These functional and metabolic alterations induced by palmitoyl- l -carnitine were attenuated by ranolazine (5, 10, and 20 ,m) in a concentration-dependent manner. In contrast, dichloroacetate (1 and 10 mm) did not attenuate palmitoyl- l -carnitine-induced mechanical and metabolic derangement. In the normal (palmitoyl- l -carnitine-untreated) heart, however, ranolazine did not modify mechanical function and energy metabolism. These results suggest that ranolazine attenuates palmitoyl- l -carnitine-induced mechanical and metabolic derangement in the rat heart, and that the beneficial action of ranolazine is not because of the energy-sparing effect or activation of pyruvate dehydrogenase. [source] Dysregulation of the stress response in asthmatic childrenALLERGY, Issue 1 2009K. N. Priftis The stress system co-ordinates the adaptive responses of the organism to stressors of any kind. Inappropriate responsiveness may account for increased susceptibility to a variety of disorders, including asthma. Accumulated evidence from animal models suggests that exogenously applied stress enhances airway reactivity and increases allergen-induced airway inflammation. This is in agreement with the clinical observation that stressful life events increase the risk of a new asthma attack. Activation of the hypothalamic,pituitary,adrenal (HPA) axis by specific cytokines increases the release of cortisol, which in turn feeds back and suppresses the immune reaction. Data from animal models suggest that inability to increase glucocorticoid production in response to stress is associated with increased airway inflammation with mechanical dysfunction of the lungs. Recently, a growing body of evidence shows that asthmatic subjects who are not treated with inhaled corticosteroids (ICS) are likely to have an attenuated activity and/or responsiveness of their HPA axis. In line with this concept, most asthmatic children demonstrate improved HPA axis responsiveness on conventional doses of ICS, as their airway inflammation subsides. Few patients may experience further deterioration of adrenal function, a phenomenon which may be genetically determined. [source] Inflammation and Sleep Disordered Breathing in Children: A State-of-the-Art Review,PEDIATRIC PULMONOLOGY, Issue 12 2008Aviv D. Goldbart MD Abstract Sleep disordered breathing (SDB) represents a spectrum of breathing disorders, ranging from snoring to obstructive sleep apnea syndrome (OSAS), that disrupt nocturnal respiration and sleep architecture. OSAS is a common disorder in children, with a prevalence of 2,3%. It is associated with neurobehavioral, cognitive, and cardiovascular morbidities. In children, adenotonsillectomy is the first choice for treatment and is reserved for moderate to severe OSAS, as defined by an overnight polysomnography. In adults, OSAS is the result of mechanical dysfunction of the upper airway, manifesting as severity-dependent nasal, oropharyngeal, and systemic inflammation that decrease after continuous positive airway pressure therapy. Inflammatory changes have been reported in upper airway samples from children with OSAS, and systemic inflammation, as indicated by high-sensitivity C-reactive protein (hsCRP) levels, has been shown to decrease in children with OSAS after adenotonsillectomy. Anti-inflammatory treatments for children with mild OSAS are associated with major improvements in symptoms, polysomnographic respiratory values, and radiologic measures of adenoid size. Inflammation is correlated to some extent with OSAS-related neurocognitive morbidity, but the role of inflammatory markers in the diagnosis and management of OSAS, and the role of anti-inflammatory treatments, remains to be clarified. This review examines the role of inflammation in the pathophysiology of sleep-disordered breathing in pediatric patients and the potential therapeutic implications. Pediatr. Pulmonol. 2008; 43:1151,1160. © 2008 Wiley-Liss, Inc. [source] Cardioprotection afforded by chronic exercise is mediated by the sarcolemmal, and not the mitochondrial, isoform of the KATP channel in the ratTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005David A. Brown This study was conducted to examine the role of myocardial ATP-sensitive potassium (KATP) channels in exercise-induced protection from ischaemia,reperfusion (I,R) injury. Female rats were either sedentary (Sed) or exercised for 12 weeks (Tr). Hearts were excised and underwent a 1,2 h regional I,R protocol. Prior to ischaemia, hearts were subjected to pharmacological blockade of the sarcolemmal KATP channel with HMR 1098 (SedHMR and TrHMR), mitochondrial blockade with 5-hydroxydecanoic acid (5HD; Sed5HD and Tr5HD), or perfused with buffer containing no drug (Sed and Tr). Infarct size was significantly smaller in hearts from Tr animals (35.4 ± 2.3 versus 44.7 ± 3.0% of the zone at risk for Tr and Sed, respectively). Mitochondrial KATP blockade did not abolish the training-induced infarct size reduction (30.0 ± 3.4 versus 38.0 ± 2.6 in Tr5HD and Sed5HD, respectively); however, sarcolemmal KATP blockade completely eradicated the training-induced cardioprotection. Infarct size was 71.2 ± 3.3 and 64.0 ± 2.4% of the zone at risk for TrHMR and Sed HMR. The role of sarcolemmal KATP channels in Tr-induced protection was also supported by significant increases in both subunits of the sarcolemmal KATP channel following training. LV developed pressure was better preserved in hearts from Tr animals, and was not influenced by addition of HMR 1098. 5HD decreased pressure development regardless of training status, from 15 min of ischaemia through the duration of the protocol. This mechanical dysfunction was likely to be due to a 5HD-induced increase in myocardial Ca2+ content following I,R. The major findings of the present study are: (1) unlike all other known forms of delayed cardioprotection, infarct sparing following chronic exercise was not abolished by 5HD; (2) pharmacological blockade of the sarcolemmal KATP channel nullified the cardioprotective benefits of exercise training; and (3) increased expression of sarcolemmal KATP channels was observed following chronic training. [source] Salvage reoperation for complications after ileal pouch,anal anastomosisBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 6 2005N. Dehni Background: Surgical revision may be possible in patients with a poor outcome following ileal pouch,anal anastomosis (IPAA), using either a transanal approach or a combined abdominoperineal approach with pouch revision and reanastomosis. Methods: Sixty-four patients underwent revisional surgery. The indication for salvage was sepsis in 47 patients, mechanical dysfunction in ten, isolated complications of the residual glandular epithelial cuff in three and previous intraoperative difficulties in four patients. Results: A transanal approach was used in 19 patients and a combined abdominoperineal procedure in 45. Six of the latter had pouch enlargement and 25 received a new pouch. During a mean(s.d.) follow-up of 30(25) months, three patients required pouch excision because of Crohn's disease. Two patients had poor continence after abdominoperineal surgery. At last follow-up 60 (94 per cent) of 64 patients had a functional pouch. Half of the patients experienced some degree of daytime and night-time incontinence, but it was frequent in only 15 per cent. Of 58 patients analysed, 27 of 40 who had an abdominoperineal procedure and 13 of 18 who had transanal surgery rated their satisfaction with the outcome as good to excellent. Conclusion: Surgical revision after failure of IPAA was possible in most patients, yielding an acceptable level of bowel function in two-thirds of patients. Copyright © 2005 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] | |||||||||||||