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PubMed1995

Response of guinea pig smooth and striated urethral sphincter to cromakalim, prazosin, nifedipine, nitroprusside, and electrical stimulation.

Prazosin (an alpha-1-adrenergic blocker) and cromakalim (potassium channel opener), given alone, induced significant fatigue of the urethral sphincter at a concentration of 10(-4) M; both drugs combined achieved a significant sphincteric fatigue at a concentration of 10(-5) M each. To 10(-4) M hexamethonium (ganglionic smooth muscle blocker) and 10(-4) M decamethonium (nicotinic blocker of striated muscle) the striated urethral sphincter responded like striated muscle with no detectable function of its smooth muscle component. Therefore, the striated component seems to play a dominant role in sphincteric function. With calcium depletion or in the presence of a calcium channel blocker (10(-4) M nifedipine) the urethral sphincter showed a relative enhancement of response to electrical field stimulation when compared with smooth and skeletal muscle, whose responses were both significantly reduced. This phenomenon could not be explained with calcium-dependent, inhibitory, nitric oxide-releasing nerves, as the NO-synthase blocker N-nitro-L-arginine (10(-5) M to 5 x 10(-5) M) failed to induce the enhancement of sphincter contraction during electrostimulation found with calcium depletion. Still, NO-releasing nerves might play a role in sphincteric relaxation because sodium nitroprusside (10(-5) M) induced a significant relaxation of the urethral sphincter precontracted with 80 mM potassium. The potential to weaken sphincteric closure with drugs, exemplified by the results obtained in response to prazosin and cromakalim, would represent a therapeutic advance in the patient with neurogenic bladder dysfunction.

Amino Acid Oxidoreductases↗
PubMed1999

Endothelin-1 induces endothelial barrier failure in the cat hindlimb.

Our purpose was to see whether endothelin- (ET) 1 could produce a change in the endothelial membrane barrier to protein in skeletal muscle. Previous studies in other tissues have suggested that ET-1 affects this barrier, but the measurement methods used could not exclude vascular protein extravasation due to microvascular pressure changes or the effects of changes in perfused capillary surface area. We measured the protein sieving coefficient, a specific measure of the permeability of the membrane to protein, in the isolated, perfused cat hindlimb preparation. The integral-mass balance method determined this coefficient from the changes in hematocrit and plasma protein concentration induced by a period of transvascular fluid filtration. The data clearly indicate that ET-1 produces a dose (1-20 nM) dependent increase in permeability indicative of barrier dysfunction. Hence, elevated ET levels may contribute to the perivascular edema, hemoconcentration, and impaired tissue perfusion found in systemic inflammatory response syndromes and related diseases.

Animals↗
PubMed2026

Impaired stem cell migration and divisions in Duchenne muscular dystrophy revealed by live imaging.

Dysregulation of stem cell properties is a hallmark of many pathologies, but the dynamic behaviour of stem cells in their microenvironment during disease progression remains poorly understood. Using the mdx mouse model of Duchenne Muscular Dystrophy, we developed innovative live imaging of muscle stem cells (MuSCs) in vivo, and ex vivo on isolated myofibres. We show that mdx MuSCs have impaired migration and precocious differentiation through unbalanced symmetric divisions, driven by p38 and PI3K signalling pathways, in contrast to the p38-only dependence of healthy MuSCs. Cross-grafting shows that MuSC fate decisions are governed by fibre-independent cues, whereas their migration behaviour is determined by the myofibre niche. This study provides the first dynamic analysis of dystrophic MuSC properties in vivo, reconciling conflicting reports on their function. Our findings establish DMD as a MuSC disease with niche dysfunctions, offering strategies to restore stem cell functions for improved muscle regeneration.

Stem Cells↗
PubMed2006

Exteroceptive suppression of temporalis muscle activity in subjects with high and low aggression traits.

STUDY AIM: There is evidence that the second exteroceptive suppression period of temporalis muscle activity (ES2) is modulated by the 5-HT neuronal activity in the brainstem, and the aggression trait is also connected with the cerebral 5-HT neuronal innervation. We therefore studied the temporalis ES2 in subjects with high and low aggression traits. METHODS: Sixty-five subjects with either low or high aggression trends, judged by clinical interview, answered the Zuckerman-Kuhlman Personality Questionnaire (ZKPQ), the Zuckerman Sensation Seeking Scales (SSS) and the Plutchik-van Praag Depression Inventory (PVP). These also underwent a temporalis ES2 test procedure. Twenty-two subjects with a high ZKPQ aggression trait score and 27 with a low score were selected for data analysis. RESULTS: On average, the high aggression group displayed significantly reduced temporalis ES2 duration, elevated ZKPQ Impulsive Sensation Seeking, Neuroticism-Anxiety and Aggression-Hostility, and PVP scores. The personality traits were not related with either latency or duration of temporalis ES2 in any group. The PVP score, however, was negatively correlated with ES2 duration in all 49 subjects. CONCLUSIONS: This study demonstrates neurophysiologic signs of brainstem dysfunction in subjects with high aggression traits.

Adult↗
PubMedDate not supplied

Effects of limb elevation on abnormally increased intramuscular pressure, blood perfusion pressure, and foot sensation: an experimental study in humans.

OBJECTIVES: To study the effects of limb elevation on abnormally increased intramuscular pressure (IMP) and blood perfusion pressure in the anterior compartment of the leg. DESIGN: An experimental cross-over design. The test leg was elevated and the control leg was kept at heart level. PARTICIPANTS: Eight healthy subjects with a mean age of twenty-nine years. INTERVENTION: IMP was measured in the anterior compartment of the leg, and blood pressures were taken in the left arm and both legs. Four variables were recorded (with or without venous stasis, with or without plaster cast). All measurements were made simultaneously in both legs. RESULTS: When the leg was obstructed by venous stasis and elevated to between thirty-three and thirty-five centimeters, IMP decreased from 16.5 to 9.8 millimeters of mercury. When venous stasis was simulated in a level casted leg, the IMP was thirty-eight (SD = 6.4) millimeters of mercury but showed only a slight decline to thirty-five (SD = 7.8) millimeters of mercury after the leg was elevated. Blood perfusion pressure fell significantly once the leg was elevated, decreasing 53 percent from forty-seven (SD = 7.8) to twenty-five (SD = 8.0) millimeters of mercury (p < 0.001). All subjects experienced loss of foot sensation in the elevated limb. CONCLUSION: In those cases in which venous stasis increased IMP levels in the anterior compartment of the leg, elevating the limb produced a 40 percent reduction in IMP. However, limb elevation did not significantly reduce increased IMP levels when the venous stasis occurred in a casted leg. Therefore, we believe casted legs in which abnormally increased IMP is attributable to venous stasis should not be elevated above heart level because elevation induces low perfusion pressure and sensory dysfunction.

Adult↗
PubMedDate not supplied

Ankylosing spondylitis: integrated clinical and physiological perspectives.

This hypothesis paper draws upon clinical epidemiological and physiological perspectives of axial muscle tone relevant to ankylosing spondylitis (AS). Skeletal muscle tonus is the property of intrinsic tension or resistance to stretch with no additional muscle contraction. The interpretations call attention to novel concepts of the intrinsic axial muscular system contributions to enthesopathic lesions in AS. The axial kinematic chain extends from the entire spine to the posterior aspects of the lower extremities and is essential for postural and mobility functions. Muscles and articular cartilage derive from common embryological precursor cells and are complexly coordinated in the maintenance of postures and dynamic functions. A definitive link between axial muscular dysfunction and respective joint pathology has not yet been demonstrated in AS. However, the following clinical epidemiological and physiological observations raise the possibility of a relationship between axial muscular hypertonicity and AS, which will be reviewed sequentially.

Adolescent↗
PubMed1993

Myocarditis as a complication in scleroderma patients with myositis.

This report describes six diffuse scleroderma (PSS) patients with skeletal muscle myositis accompanied by severe myocarditis, diagnosed by CPK-MB elevation in conjunction with severe left ventricular (LV) hypokinesis. Although the myositis improved with steroid therapy in all patients, those treated with steroids alone died due to progressive LV failure. This experience suggests that the LV dysfunction in PSS patients with myositis may have an inflammatory component. Since the myocarditis may not be clinically apparent initially, it is suggested that CPK-MB fractionation and studies of LV function are undertaken in all PSS patients with myositis. The optimal treatment of this disorder, however, has yet to be determined.

Adult↗
PubMed1982

Gastrointestinal manifestations of the muscular dystrophies.

Skeletal and cardiac muscle involvement is a recognized feature of the muscular dystrophies. Visceral smooth muscle involvement of the gastrointestinal tract is not as well appreciated. Gastrointestinal symptoms may herald the onset of a muscular disorder and may be the predominant feature of the disorder. In some instances, smooth muscle dysfunction may be the only clinical manifestation of the disease. The gastrointestinal manifestations of the various muscular dystrophies are reviewed. Clinical, radiographic, and histologic features are discussed. Further study of the histopathology and pathophysiology of visceral smooth muscle involvement in the muscular dystrophies will have a substantial impact on treatment that, to a large extent, remains empiric.

Adolescent↗
PubMed2006

Vastus medialis: anatomical and functional considerations and implications based upon human and cadaveric studies.

OBJECTIVE: To provide an electrophysiological and functional description of the vastus medialis (VM) and contrast it to an anatomical description. METHODS: Motor points of all superficial portions of the quadriceps were identified on the dominant side of 8 human subjects and electrically stimulated to achieve a light contraction to trace and measure the orientation of the fibers. Electromyography of the VM was then recorded over 2 motor points during isometric and isokinetic maximum knee extensions. An independent laboratory dissected 39 cadaveric specimens focusing on fiber orientations and distal insertions of the VM. RESULTS: Results revealed 5 motor points for the quadriceps: 1 point for the vastus lateralis, 1 point for the rectus femoris (RF), and 3 points for the VM. The 3 VM motor points suggest 3 separate groups of fibers: proximal (pf), median (mf), distal (df). Fiber orientations ranged from 45 degrees for VMpfs to 55 degrees for VMdfs. Motor point stimulation and anatomical dissection clearly showed that the VMpfs and VMmfs were inserted on a tendon common to the RF, whereas VMdfs were attached directly to the medial aspect of the patella. Furthermore, the VMpfs were more active (P < .05) than VMdfs during maximum knee extensions. CONCLUSION: The anatomy, motor points, and electromyography clearly support an important distinction between the VMpfs and VMdfs. The role of the VMpfs would be one of assisting the RF in knee extension, whereas the VMdfs would track the patella medially without participating in knee extension. Because of these anatomical and functional differences, the VMpfs and VMdfs should be addressed very differently during quadriceps rehabilitation in patellofemoral dysfunctions.

Adult↗
PubMed2001

Effect of levator ani muscle contraction on urethrovesical and anorectal pressures and role of the muscle in urination and defecation.

OBJECTIVES: To investigate the effect of levator ani muscle (LAM) (the main muscle in the pelvic floor) contraction on the anorectal and urethrovesical pressures and elucidate its role in the mechanisms of defecation and urination. METHODS: In 18 healthy volunteers (10 men and 8 women; mean age 38.6 +/- 10.2 years), the LAM was stimulated to contract by a concentric needle electrode, and the anal, rectal, urethral, and vesical pressure responses were recorded. The test was repeated once after LAM anesthetization with Xylocaine injection and again after saline instead of Xylocaine injection into the LAM. RESULTS: On LAM stimulation, the anal and urethral pressures had a significant decline (both P <0.05), and the rectal and vesical pressures exhibited no significant changes (both P >0.05). The anal, rectal, urethral, and vesical pressures did not show significant changes on stimulation of the anesthetized LAM; after saline injection, the pressure response was similar to that before injection (P >0.05). These results were reproducible. CONCLUSIONS: LAM contraction lowers the anal and urethral pressures and appears to assist in the evacuation process. We therefore propose that the LAM is a muscle of evacuation and that LAM dysfunction could lead to defecation and urination disorders.

Adolescent↗
PubMed2005

Neurovascularized free short head of the biceps femoris muscle transfer for one-stage reanimation of facial paralysis.

The single-stage technique for cross-face reanimation of the paralyzed face without nerve graft is an improvement over the two-stage procedure because it results in early reinnervation of the transferred muscle and shortens the period of rehabilitation. On the basis of an anatomic investigation, the short head of the biceps femoris muscle with attached lateral intermuscular septum of the thigh was identified as a new candidate for microneurovascular free muscle transfer. The authors performed one-stage transfer of the short head of the biceps femoris muscle with a long motor nerve for reanimation of established facial paralysis in seven patients. The dominant nutrient vessels of the short head were the profunda perforators (second or third) in six patients and the direct branches from the popliteal vessels in one patient. The recipient vessels were the facial vessels in all cases. The length of the motor nerve of the short head ranged from 10 to 16 cm, and it was sutured directly to several zygomatic and buccal branches of the contralateral facial nerve in six patients. One patient required an interpositional nerve graft of 3 cm to reach the suitable facial nerve branches on the intact side. The period required for initial voluntary movement of the transferred muscles ranged from 4 to 10 months after the procedures. The period of postoperative follow-up ranged from 5 to 42 months. Transfer of the vascularized innervated short head of the biceps femoris muscle is thought to be an alternative for one-stage reconstruction of the paralyzed face because of the reliable vascular anatomy of the muscle and because it allows two teams to operate together without the need to reposition the patient. The nerve to the short head of the biceps femoris enters the side opposite the vascular pedicle of the muscle belly, and this unique relationship between the vascular pedicle and the motor nerve is anatomically suitable for one-stage reconstruction of the paralyzed face. As much as to 16 cm of the nerve can be harvested, and the nerve is long enough to reach the contralateral intact facial nerve in almost all cases. The lateral intermuscular septum, which is attached to the short head, provides "anchor/suture-bearing" tissue, allowing reliable fixations to the zygoma and the upper and lower lips to be achieved. In addition, the scar and deformity of the donor site are acceptable, and loss of this muscle does not result in donor-site dysfunction.

Adult↗
PubMed1996

Assessment of the voluntary activation of the diaphragm using cervical and cortical magnetic stimulation.

The twitch occlusion technique is a promising tool for use in accessing central drive to the diaphragm and determining maximal transdiaphragmatic pressure (Pdi) from submaximal efforts. It clinical use is limited by difficulties inherent to bilateral electrical stimulation (BES) of the phrenic nerves. This study was designed to revisit the technique using cervical magnetic stimulation (CMS). In addition, the effects of a voluntary contraction on diaphragm response to magnetic stimulation of the cortex (CxMS) were studied. Seven volunteers aged 23-33 yrs were studied. Pdi was determined at relaxed functional residual capacity (FRC) in response to BES (Pdi,P-ES) and CMS (Pdi,p-CMS), and the effects of an increasing voluntary contraction (Pdi, vol) were assessed, The same procedure was applied to CxMS. Pdi,p-CMS at relaxed FRC was 27.5 +/- 2.2 cmH2O (mean+/-SEM), about 20% higher than Pdi,p-ES, and reported previously. Pd,p-CMS linearly decreased with Pdi, vol, and six out of seven subjects were capable of producing voluntary contractions sufficient to extinguish the twitch. More complex patterns were observed with CxMS. Cervical magnetic stimulation provides diaphragmatic twitch occlusion data very similar to bilateral electrical phrenic stimulation. Magnetic stimulation, be it cervical or cortical, could probably be helpful for the assessment of central and peripheral mechanisms of diaphragmatic dysfunction in the clinical setting.

Adult↗
PubMed2001

In vivo gene electroporation of glial cell line-derived neurotrophic factor (GDNF) into skeletal muscle of SOD1 mutant mice.

Motor neurons degenerate with intracellular vacuolar change and eventually disappear in spinal cords of SOD1 mutant mice, resembling human amyotrophic lateral sclerosis (ALS). The GDNF gene was electroporatically transferred into the leg muscles of SOD1 mutant mice and expressed in muscle cells. This gene therapy with GDNF delayed the deterioration of motor performance, being retrogradely transported into spinal motor neurons. However, the number of the motor neurons and survival of the mutant mice were not improved by GDNF treatment. These results indicate that in vivo gene electroporation of GDNF into muscles could be an appropriate therapeutic approach to ameliorate an early dysfunction of motor neurons in SOD1 mutant mice, but further improvement is needed to use this gene transfer as an effective treatment of ALS.

Animals↗
PubMed2000

Habitual activities and peak aerobic capacity in patients with asymptomatic and symptomatic left ventricular dysfunction.

BACKGROUND: A reduced level of daily activities is thought to be an important determinant of aerobic exercise intolerance in patients with chronic heart failure chronic heart failure; however, few data exist about the relationship between habitual physical activity level and peak aerobic capacity in patients at different clinical stages of left ventricular dysfunction. STUDY OBJECTIVES: The purposes of this study were as follow: (1) to validate a simple interviewer-administered scoring system for evaluation of habitual physical activity level of patients with chronic heart failure and asymptomatic left ventricular dysfunction (ALVD); (2) to determine the relationship between habitual physical activity level and peak aerobic capacity in chronic heart failure and ALVD patients; and (3) to compare habitual activity levels among different New York Heart Association (NYHA) classes in these populations. SETTING: Cardiology division at a tertiary-care hospital. STUDY POPULATION: We studied 167 consecutive patients with chronic heart failure (NYHA class I to III), 40 patients with ALVD, and 52 healthy subjects (HS). MEASUREMENTS AND RESULTS: Habitual physical activity level was evaluated by means of an interview-based activity scoring system considering leisure time and occupational activities and also recent deconditioning events (eg, hospital admissions); a final activity score (AS) ranging from 0.8 to 5 was obtained. All patients and HS performed a symptom-limited cardiopulmonary exercise test up to a respiratory exchange ratio of > or = 1.1. AS was an independent predictor of peak oxygen consumption (VO(2)) in all groups, with a significantly higher VO(2) vs AS relationship slope in the ALVD and HS groups than in the chronic heart failure group. Moreover, AS was found to be significantly lower in chronic heart failure than in ALVD patients and HS (1.6 +/- 0.6 vs 2.2 +/- 0.7 vs 3.5 +/- 1.1, respectively; p < 0.0001), as was peak VO(2) (14.7 +/- 3.7 mL/kg/min vs 20 +/- 4 mL/kg/min vs 33.1 +/- 10 mL/kg/min, respectively; p < 0.0001), but the latter differences were canceled after adjusting for AS values. Significant AS and peak VO(2) reductions were observed in chronic heart failure patients with NYHA class progression from I to III. CONCLUSIONS: Habitual physical activity level is progressively decreased with worsening of heart failure symptoms and is related to peak aerobic capacity in both chronic heart failure and ALVD patients. However, this relationship appears to be weak in patients with chronic heart failure, whereas daily activity is a strong independent predictor of peak aerobic capacity both in ALVD patients and HS. This may be related to the intervention of factors other than skeletal muscle deconditioning in the exercise pathophysiology of chronic heart failure patients.

Activities of Daily Living↗
PubMed2001

Mitochondrial alterations caused by defective peroxisomal biogenesis in a mouse model for Zellweger syndrome (PEX5 knockout mouse).

Zellweger syndrome (cerebro-hepato-renal syndrome) is the most severe form of the peroxisomal biogenesis disorders leading to early death of the affected children. To study the pathogenetic mechanisms causing organ dysfunctions in Zellweger syndrome, we have recently developed a knockout-mouse model by disrupting the PEX5 gene, encoding the targeting receptor for most peroxisomal matrix proteins (M Baes, P Gressens, E Baumgart, P Carmeliet, M Casteels, M Fransen, P Evrard, D Fahimi, PE Declercq, D Collen, PP van Veldhoven, GP Mannaerts: A mouse model for Zellweger syndrome. Nat Genet 1997, 17:49-57). In this study, we present evidence that the absence of functional peroxisomes, causing a general defect in peroxisomal metabolism, leads to proliferation of pleomorphic mitochondria with severe alterations of the mitochondrial ultrastructure, changes in the expression and activities of mitochondrial respiratory chain complexes, and an increase in the heterogeneity of the mitochondrial compartment in various organs and specific cell types (eg, liver, proximal tubules of the kidney, adrenal cortex, heart, skeletal and smooth muscle cells, neutrophils). The changes of mitochondrial respiratory chain enzymes are accompanied by a marked increase of mitochondrial manganese-superoxide dismutase, as revealed by in situ hybridization and immunocytochemistry, suggesting increased production of reactive oxygen species in altered mitochondria. This increased oxidative stress induced probably by defective peroxisomal antioxidant mechanisms combined with accumulation of lipid intermediates of peroxisomal beta-oxidation system could contribute significantly to the pathogenesis of multiple organ dysfunctions in Zellweger syndrome.

Adenosine Triphosphate↗
PubMed1983

The role of calcium in cellular dysfunction.

In order to study the effects of substances with selective Ca2+ entry blocking properties which enhance the tolerance to ischemia by preventing a toxic calcium overload, attempts are made to localize calcium ultrastructurally. Under normoxic conditions, a mobile pool of Ca2+ is localized in synaptic vesicles and in mitochondria of brain cells; in mitochondria of cardiac, skeletal and vascular smooth muscle; and in the junctional SR of fast skeletal muscle. A plasmalemmabound pool of Ca2+ is present in cardiac and slow skeletal muscle. Ischemia or hypoxia induce marked shifts in calcium of both the mobile and the plasmalemma-bound pools. Cardiac and skeletal muscle mitochondria scavenge huge amounts of calcium, especially during the reperfusion period following prolonged circulatory arrest. The membrane-bound Ca2+ is lost under these conditions. In the hypoxic brain, the amount of intracellular calcium clearly parallels the degree of damage. Observations made on peripheral and brain blood vessels show that high amounts of precipitated Ca2+ cover the myofilaments upon induction of spasm. The antispasmodic effect of the selective Ca2+-entry blockers flunarizine and lidoflazine is morphologically characterized by the absence of Ca2+ over the myofilaments in muscle treated as such whereas the extracellular Ca2+ remained the same. This observation indicates that the entry of Ca2+ is blocked at the level of the plasma membrane. In the heart and brain these drugs preserve the structural integrity of the plasmalemma-surface coat complex and thereby protect the cells against the devastating consequences of cellular calcium overload.

Animals↗
PubMed2003

Apical left ventricular aneurysm without atrio-ventricular block due to a lamin A/C gene mutation.

BACKGROUND: Mutations in LMNA gene encoding two ubiquitously expressed nuclear proteins, lamins A and C, give rise to up to 7 different pathologies affecting specific tissues. Three of these disorders affect cardiac and/or skeletal muscles with atrio-ventricular conduction disturbances, dilated cardiomyopathy and sudden cardiac death as common features. RESULTS: A new LMNA mutation (1621C>T, R541C) was found in two members of a French family with a history of ventricular rhythm disturbances and an uncommon form of systolic left ventricle dysfunction. The two patients: the proband and his daughter, were affected and exhibited an atypical form of dilated cardiomyopathy with an unexplained left ventricle aneurysm revealed by ventricular rhythm disturbances without atrio-ventricular block. CONCLUSION: This finding reinforces the highly variable phenotypic expression of LMNA mutation and emphasizes the fact that LMNA mutations can be associated with different cardiac phenotypes.

Adult↗