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At least 1,243 records · Page 69Linked to original sources
PubMed2005

Hypercholesterolemia impairs reactive hyperemic vasodilation of 2A but not 3A arterioles in mouse cremaster muscle.

Hypercholesterolemia and atherosclerosis have been associated with changes in the microvasculature, in particular with endothelial dysfunction. In the present study, the impact of atherogenic conditions on arteriolar vasomotor control was determined. Arteriolar [second-order (2A) and third-order (3A) arterioles; diameter range: 9-37 microm] responses during reactive hyperemia (RH) were determined in cremaster muscle of anesthetized mice. C57Bl/6 mice on normal rodent chow were used as controls and high-fat/high-cholesterol (HFC)-fed C57Bl/6 and ApoE3-Leiden mice as hypercholesterolemic mice. The HFC diet resulted in time-dependent increases in plasma cholesterol and triglyceride concentrations (P < 0.001), which were more pronounced in ApoE3-Leiden mice (P < 0.001). In control mice, inhibition of nitric oxide (NO) synthesis with Nomega-nitro-L-arginine (L-NNA) reduced baseline diameter from 17.9 +/- 1.2 to 15.9 +/- 1.3 microm (P < 0.05) and decreased the duration of RH [time to 50% (t50) of recovery: 23.3 +/- 3.6 vs. 12.5 +/- 1.3 s (P = 0.003)]. t50 was longer in 2A versus 3A arterioles (33 +/- 3 vs. 18 +/- 2 s, P < 0.001) and increased with wall shear rate at the beginning of RH in 2A arterioles only. Compared with control mice, RH duration was reduced in 2A arterioles of HFC mice (t50: 11 +/- 2 s, P < 0.001 vs. control) but not affected in 3A vessels. L-NNA did not affect baseline diameter in HFC mice and reduced t50 only in "slow" responders (t50 > or = 10 s). It is concluded that hypercholesterolemia results in an impairment of NO-mediated vasomotor control in 2A but not 3A arterioles during dynamic changes of perfusion like RH. 2A arterioles likely therefore represent the functional locus of endothelial dysfunction during atherogenic conditions.

Abdomen↗
PubMed2002

Etiologic theories of idiopathic scoliosis: the apical spinal deformity--relevance to surgical practice.

UNLABELLED: The current successful management of idiopathic scoliosis is an orthopaedic and not a paediatric responsibility. Hence the immediate aim of etiologic research is to improve surgical treatments based on a better understanding of the causation of the deformity. This focuses attention on the pathomechanisms of the spinal and ribcage deformities. The mechanisms of spinal deformity about the apex are unresolved but may be caused by forces created in the anterior spinal column. Some current theories with practical application involve (1) front-back spinal growth mechanisms, (2) rib growth asymmetry and (3) muscles. CONCLUSIONS: The application of theory to surgical practice is advanced for concepts of front-back spinal growth asymmetry but rib hump reassertion occurs after surgery and these concepts ignore the ribcage as a possible factor in scoliosis pathogenesis. A theory of ribcage asymmetry involving concave rib overgrowth is beginning to be evaluated surgically. After surgery for IIS and AIS reassertion of the deformity has been shown to involve preoperative spinal and concave rib factors; the larger the concave rib-spinal angle the better results at 2-5 year. Muscular factors that may trigger/exacerbate the apical spinal deformity of scoliosis need more research. The concept that AIS pathogenesis involves putative neuromuscular dysfunction that deforms an immature spine is considered likely by several workers.

Adolescent↗
PubMed1996

[New trends in the study of the primary fibromyalgic syndrome].

The study of 1240 patients making complaints of osteomuscular pains showed that 9.6% had clinical signs of primary fibromyalgia (PF). It provided new data on the clinical signs of PF, clinical and biochemical changes in this syndrome. The diagnostic and informative values of some signs and symptoms of PF are compared and new approaches to optimizing diagnostic criteria are outlined in the paper. The paper also gives new data on the combined therapy for PF, including the use of dimexide with nonhormonal antiinflammatory agents and sessions of acupuncture that promotes the normalization of dysfunctions. This may be useful for PF patients due to easy-to-use, available, and inexpensive treatment.

Biopsy↗
PubMedDate not supplied

Cardiac Na(+) channel dysfunction in Brugada syndrome is aggravated by beta(1)-subunit.

BACKGROUND: Mutations in the gene encoding the human cardiac Na(+) channel alpha-subunit (hH1) are responsible for chromosome 3-linked congenital long-QT syndrome (LQT3) and idiopathic ventricular fibrillation (IVF). An auxiliary beta(1)-subunit, widely expressed in excitable tissues, shifts the voltage dependence of steady-state inactivation toward more negative potentials and restores normal gating kinetics of brain and skeletal muscle Na(+) channels expressed in Xenopus oocytes but has little if any functional effect on the cardiac isoform. Here, we characterize the altered effects of a human beta(1)-subunit (hbeta(1)) on the heterologously expressed hH1 mutation (T1620M) previously associated with IVF. METHODS AND RESULTS: When expressed alone in Xenopus oocytes, T1620M exhibited no persistent currents, in contrast to the LQT3 mutant channels, but the midpoint of steady-state inactivation (V(1/2)) was significantly shifted toward more positive potentials than for wild-type hH1. Coexpression of hbeta(1) did not significantly alter current decay or recovery from inactivation of wild-type hH1; however, it further shifted the V(1/2) and accelerated the recovery from inactivation of T1620M. Oocyte macropatch analysis revealed that the activation kinetics of T1620M were normal. CONCLUSIONS: It is suggested that coexpression of hbeta(1) exposes a more severe functional defect that results in a greater overlap in the relationship between channel inactivation and activation (window current) in T1620M, which is proposed to be a potential pathophysiological mechanism of IVF in vivo. One possible explanation for our finding is an altered alpha-/beta(1)-subunit association in the mutant.

Amino Acid Substitution↗
PubMed1994

Evaluation of pulsatile and nonpulsatile flow in capillaries of goat skeletal muscle using intravital microscopy.

It is commonly believed that pulsatile flow generated by the pumping action of the heart is dampened out by the time it reaches the microcirculation. In clinical practice, most of the cardiopulmonary bypass pumps and ventricular assist devices are nonpulsatile. To test the hypothesis that pulsatile flow generated by the heart does exist at the microvascular level, intravital microscopy of a large animal model (goat) was developed to visualize and to videorecord the surface microcirculation of the flexor carpi ulnaris muscle from the right forelimb. Density of perfused capillaries and red blood cell velocity in capillaries were measured in five goats during pulsatile perfusion provided by the heart and during a subsequent 3-hr period of nonpulsatile perfusion provided by a centrifugal ventricular assist device (Centrimed, Sarns 3M) that bypassed the heart. Throughout the experiment, the heart rate, innominate artery mean blood pressure, and flow remained unchanged. During the pulsatile regimen, velocities showed regular fluctuations that coincided with the period of the cardiac cycle (range of periods: 0.5-0.8 sec). The peak velocity amplitudes (range: 0.25-0.55 mm/sec) correlated directly with the amplitude of the pulse pressure. During the nonpulsatile regimen, no such correlations were seen. During pulsatile flow and during the 3-hr nonpulsatile period, capillary density remained stable at 24 capillaries/mm of test line but there were significant increases in red cell velocity, from 0.8 to 1.2 mm/sec (P < 0.05), and in coefficient of variation of velocity (used as an index of flow heterogeneity), from 19 to 34% (P < 0.05). We conclude that (1) pulsatility exists in the capillary bed and that it directly correlates with the pumping action of the heart and (2) nonpulsatile flow produced by the ventricular assist device does not cause an acute deterioration in microvascular perfusion. We interpret the increase in heterogeneity of flow as an early sign of microvascular dysfunction. Prolonged use of the nonpulsatile device may, therefore, lead to deterioration in perfusion that could compromize the function of the organ.

Animals↗
PubMed2001

Neurogenic bladder in Lambert-Eaton myasthenic syndrome and its response to 3,4-diaminopyridine.

Autonomic dysfunction, as well as neuromuscular involvement, is a common manifestation of Lambert-Eaton myasthenic syndrome (LEMS). Dry mouth and impotence have been described as typical features of autonomic dysfunction, but neurogenic bladder is infrequent or subclinical in LEMS. We report a patient with neurogenic bladder secondary to LEMS whose condition responded to 3,4-diaminopyridine (3,4-DAP). In this patient's serum, results of repeated measurement with P/Q-type VGCC antibodies proved positive, but not with N-type VGCC and synaptotagmin antibodies. A review of the literature turned up a few patients with voiding dysfunction related to LEMS, but no urodynamic studies were done on these patients. Ours is the first case in which 3,4-DAP was efficacious in treating LEMS and neurogenic bladder. Responses of 3,4-DAP in urodynamic studies suggest that in this LEMS patient neurogenic bladder was caused by defective neurotransmission both in the autonomic detrusor and skeletal abdominal muscles.

4-Aminopyridine↗
PubMed2005

Downbeating nystagmus and muscle spasms in a patient with glutamic-acid decarboxylase antibodies.

PURPOSE: To report the ophthalmic findings and response to treatment in a patient with glutamic-acid decarboxylase antibodies. DESIGN: Case report. METHODS: A 55-year-old woman developed progressive, painful, low back muscle spasms, vertical diplopia, downbeating nystagmus, and asymmetric appendicular ataxia. RESULTS: Downbeating nystagmus was present in primary gaze with an alternating skew deviation in lateral gaze. Serum and cerebrospinal fluid GAD antibodies were detected. Treatment with diazepam led to resolution of spasticity, whereas repeated courses of intravenous immunoglobulin improved cerebellar function, including appendicular ataxia and downbeating nystagmus. CONCLUSIONS: Patients with GAD antibodies may have elements of both Stiff-person syndrome (muscle rigidity and spasms) and prominent cerebellar dysfunction. Treatment with diazepam rapidly improved Stiff-person symptoms, whereas IVIg was partially effective at the early stage of cerebellar dysfunction.

Autoantibodies↗
PubMed2006

Nerve conduction studies in relation to residual fatigue in Guillain-Barré syndrome.

Many Guillain-Barré syndrome (GBS) and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) patients recover well, but suffer from excessive fatigue, which may persist for years and reduce the quality of life considerably. In order to determine whether residual subclinical peripheral nerve dysfunction is a possible underlying mechanism of fatigue, we performed standardized nerve conduction (NC) studies in 16 fatigued patients, mean 6.5 years after diagnosis. Thirteen were relatively well recovered from GBS and 3 had stable CIDP. In contrast to CIDP, most NC values in GBS patients were remarkably restored and within normal values. No correlations were found between the electrophysiological findings and the fatigue scores,muscle strength, or functional scores. This study demonstrates that fatigue in GBS is not explained by residual nerve dysfunction, using conventional NC measurements.

Action Potentials↗
PubMed2005

Motor unit synchronization is reduced in anterior knee pain.

UNLABELLED: Anterior knee pain (AKP) is common and has been argued to be related to poor patellofemoral joint control due to impaired coordination of the vasti muscles. However, there are conflicting data. Changes in motor unit firing may provide more definitive evidence. Synchronization of motor unit action potentials (MUAPs) in vastus medialis obliquus (VMO) and vastus lateralis (VL) may contribute to coordination in patellofemoral joint control. We hypothesized that synchronization may be reduced in AKP. Recordings of single MUAPs were made from VMO and multiunit electromyograph (EMG) recordings were made from VL. Averages of VL EMG recordings were triggered from the single MUAPs in VMO. Motor units in VL firing in association with the VMO motor units would appear as a peak in the VL EMG average. Data were compared to previous normative data. The proportion of trials in which a peak was identified in the triggered averages of VL EMG was reduced in people with AKP (38%) compared to controls (90%). Notably, although 80% of subjects had values less than controls, 20% were within normal limits. These results provide new evidence that motor unit synchronization is modified in the presence of pain and provide evidence for motor control dysfunction in AKP. PERSPECTIVE: This study shows that coordination of motor units between the medial and lateral vasti muscles in people with anterior knee pain is reduced compared to people without knee pain. It confirms that motor control dysfunction is a factor in this condition and has implications for selection of rehabilitation strategies.

Action Potentials↗
PubMed2002

Targeted "knockdown" of channel expression in vivo with an antisense morpholino oligonucleotide.

We have examined whether antisense morpholino oligonucleotides (morpholinos) can be used as a tool to suppress or "knockdown" the expression of ion channels during development of the zebrafish. Because the acetylcholine receptor channel is well characterized in zebrafish and is abundant as skeletal muscle is found throughout the body, we sought to knock down its expression as a general test of the feasibility of this approach. A 25-mer morpholino was designed to target the 5' region of the cloned alpha-subunit and was injected into early stage blastulae in order to trap it in all developing cells. From the time of hatching (early on the third day of development) and for a few days after, a fraction of the injected embryos were immobile, i.e. were "morphant". Injection of blastulae without the morpholino or with a control morpholino containing four mispaired bases did not affect the embryos. Although the morphant embryos were generally normal in appearance, they lacked staining with alpha-bungarotoxin or an alpha-subunit-specific monoclonal antibody. In whole muscle cell recordings from morphant embryos, miniature end-plate potentials were undetectable in many of the cells and in most they had a slower, immature time course. These results are consistent with a greatly reduced, dysfunctional level of expression of acetylcholine receptors in morphant embryos. Because of their stability and specificity, morpholinos should prove useful for targeted deletion of transmitter receptors and channels in developing zebrafish and possibly in other preparations.

Animals↗
PubMed1996

Pathology of skeletal muscle and impaired respiratory chain function in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency with the G1528C mutation.

Lactic acidosis and mitochondrial abnormalities have been reported in long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency. We studied muscle morphology and the respiratory chain function in ten patients with LCHAD deficiency and the G1528C mutation. In eight cases the light microscopy of muscle specimens showed fatty infiltration and fibre degeneration. The degenerated fibres appeared as ragged red fibres in four cases. Electron microscopy revealed enlarged mitochondria often with swollen appearance in four out of seven patients. The number of mitochondria had also increased. Complex I associated enzyme activities in muscle mitochondria were decreased in five out of seven patients, and in three of them Complex II or II + III associated activities were also affected. We suggest that the reason for respiratory chain dysfunction and structural changes of mitochondria is the accumulation of toxic intermediates of fatty acid beta-oxidation in mitochondria. Because these changes may confound the differential diagnostics between LCHAD deficiency and respiratory chain defects, awareness of their frequency is important.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed2004

The relationship between clinical stage, prognosis and myocardial damage in patients with Duchenne-type muscular dystrophy: five-year follow-up study.

UNLABELLED: The evaluation of myocardial damage by [123I] 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) imaging, which represents free fatty acid metabolism, has not been reported in patients with Duchenne-type muscular dystrophy (DMD). To date, the relationship between clinical stage, prognosis and myocardial damage has not been evaluated by radionuclear cardiac imaging. The main goal of this study was to elucidate the relationship of quantitative indices of myocardial damage obtained by radionuclear cardiac imaging ([201Tl] and [123I] BMIPP) to clinical stage and incidence of severe cardiac events in patients with Duchenne-type muscular dystrophy (DMD). METHODS: The study population consisted of 28 male patients with DMD. The average age at the beginning of observation was 19.1 +/- 7.4 yrs. Nuclear tomographic imaging was performed using [201Tl] and [123I] BMIPP. The mid-ventricular short axial slices were classified into four anatomical regions, and the normalized count data in these areas (TL, BM) were obtained. The endpoint was the occurrence of heart failure during the follow up period. RESULTS: Thirteen cases of heart failure occurred during the 5-year follow-up period, including three cases with cardiac death due to congestive heart failure. Clinical staging correlated directly with TL (p = 0.0118) and BM (p = 0.0401) in the whole left ventricle. In regional TL analysis, an association was observed only in the septum (p = 0.0151), and in the anterior (p = 0.0361) region. The only discrepancy between the tracer parameters (TL - BM) in the septum was observed with the radionuclear cardiac values, which exhibited a relationship with cardiac events (p = 0.0124). This discordance, TL < BM, was contrary to that usually observed in patients with ischemic heart disease. CONCLUSION: The septum is the critical area of significance for cardiac events and outcome in patients with DMD. The uptake of [201Tl] in this area was representative of the clinical stage, and TL-BM correlated well with the prognosis.

Adult↗
PubMed2002

Neurofilament accumulation at the motor endplate and lack of axonal sprouting in a spinal muscular atrophy mouse model.

Mutations of survival of the motor neuron gene (SMN1) are responsible for spinal muscular atrophy (SMA), a common genetic cause of death in childhood. The cellular mechanism by which mutations of SMN1 are responsible for the selective neuromuscular defect and motor neuron cell degeneration observed in SMA has not been described. We have previously generated mice carrying a homozygous deletion of Smn exon 7 directed to neurons. We report here that these mutant mice display a dramatic and progressive loss of motor axons involving both proximal and terminal regions, in agreement with the skeletal muscle denervation process and disease progression. Moreover, we found massive accumulation of neurofilaments, including phosphorylated forms, in terminal axons of the remaining neuromuscular junctions. This aberrant cytoskeletal organization of synaptic terminals was associated with reduction of branched structures of the postsynaptic apparatus and defect of axonal sprouting in mutant mice. Together, these findings may be responsible for severe motor neuron dysfunction, and suggest that loss of motor neuron cell bodies results from a 'dying-back' axonopathy in SMA. Smn mutant mice should represent a valuable model for elucidating the pathway linking Smn to cytoskeletal organization.

Animals↗
PubMed1996

Effects of muscle dysfunction on lumbar spine mechanics. A finite element study based on a two motion segments model.

STUDY DESIGN: A combined finite element and optimization approach was developed to investigate the clinically relevant biomechanical parameters of the muscular lumbar spine under five quasistatic back-lifting conditions. OBJECTIVES: To quantify the effects of muscle "dysfunction" on the mechanical behavior of the lumbar spine. SUMMARY OF BACKGROUND DATA: Trunk muscles have been proven to play an important role in the normal functioning of the spine. Although passive structures of the spine are believed to be subjected increasingly to mechanical stresses when muscular support is inadequate, supportive quantitative data have been lacking. METHODS: External loads at L3-L4 for various lifting tasks were estimated experimentally and partitioned to the disc and muscles across the L3-L4 segment using an optimization scheme. These forces were incorporated into a finite element model of the ligamentous L3-L5 lumbar spine. Muscle "dysfunction" was simulated by decreasing the computed muscle forces. RESULTS: The range of motion intradiscal pressure forces in ligaments, and load across facets increased nonlinearly with the increases in trunk flexion and the load held in hands. At higher loads or at larger flexed postures, muscles were found to play a more crucial role in stabilizing the spine compared with the passive structures. Muscle "dysfunction" destabilized the spine, reduced the role of facet joints in transmitting load, and shifted loads to the discs and ligaments. CONCLUSIONS: Muscle dysfunction disturbs the normal functioning of other spinal components and may cause spinal disorders.

Biomechanical Phenomena↗
PubMed1992

Creatine kinase and enolase: intracellular enzymes serving as markers of central nervous system damage in neuropsychiatric disorders.

A frequently used method to assess cellular dysfunction and damage in humans is to document the presence of uniquely intracellular proteins in extracellular spaces. Thus, increased plasma levels of transaminases generally reflect hepatocellular damage (Lieber 1978), increases in the cardiac fractions of creatine kinase (CK, or CPK for creatine phosphokinase) or lactate dehydrogenase (LDH) are diagnostic for myocardial infarction (Armstrong et al. 1979; 1982), and increases of skeletal muscle fractions of CK may indicate myopathy (Goto 1974; Ford 1984). Similarly, a number of enzymes and proteins serve as tumor markers in a variety of malignant cancer (e.g., Concannon et al. 1974; Foti et al. 1977).

Biomarkers↗
PubMed2006

Muscle transfers involving the shoulder.

Muscle transfer provides a viable treatment option for several difficult problems involving the shoulder. Muscle transfer is often the only alternative to a salvage procedure such as shoulder fusion, and whereas salvage procedures provide pain relief at the cost of function, muscle transfer can provide pain relief while retaining acceptable function. The five most commonly encountered shoulder problems for which muscle transfer can be utilized are subscapularis rupture, irreparable rotator cuff tear, deltoid injury and dysfunction, trapezial paralysis, and serratus anterior scapular winging. Although numerous muscle transfer procedures have been described, the following procedures have proven the most reliable and are the focus of this article: 1) transfer of the pectoralis major for subscapularis rupture, 2) transfer of the latissimus dorsi for irreparable rotator cuff tears, 3) latissimus dorsi transfer for deltoid injury or dysfunction, 4) modified Eden-Lange procedure for trapezial paralysis, and 5) modified Marmor-Bechtol pectoralis major transfer for serratus anterior scapular winging.

Atrophy↗
PubMed1995

Effect of chronic angiotensin-converting enzyme inhibition on endothelial function in patients with chronic heart failure.

Chronic heart failure is associated with neurohumoral activation and alterations of the peripheral circulation and skeletal muscle. Several mechanisms are involved in the impaired peripheral perfusion, including increased sympathetic tone and increased vascular stiffness. Recently, data suggest an important role of the endothelium for perfusion of skeletal muscle in heart failure. Endothelium-dependent dilation of resistance vessels is blunted in patients with severe chronic heart failure and may be involved in the impaired reactive hyperemia in these patients. In conductance vessels, flow-dependent dilation and the nitroglycerin-induced dilator response is attenuated in congestive heart failure as compared to normal subjects, indicating both endothelial dysfunction and a defect of smooth muscle relaxation. Recent data suggest that angiotensin-converting enzyme (ACE) inhibitors can improve endothelial function of resistance vessels, reduce serum level of the soluble endothelial (vascular cell) adhesion molecule (VCAM-1) and, in addition, improve peripheral vascular function by reducing or limiting the influence of cyclo-oxygenase-dependent vasoconstricting factor(s). It is conceivable that these beneficial effects of chronic ACE inhibition are due, in part, to blockade of bradykinin degradation by the ACE and the increased endothelial synthesis of prostaglandins and/or the release of nitric oxide by enhanced tissue levels of bradykinin.

Aged↗