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PubMed1985

Creatine kinase and lactate dehydrogenase in the muscles encountered during median sternotomy and in the myocardium of the cardiac chambers.

The validity of using creatine kinase MB and lactate dehydrogenase serum isoenzymes to confirm the diagnosis of perioperative myocardial infarction in patients who have had cardiac operations has been questioned, since both have been detected in skeletal muscles. Little is known concerning the concentration of either isoenzyme in the muscles routinely encountered during median sternotomy. Since we have previously shown that the dog is an adequate model in which to study creatine kinase and lactate dehydrogenase isoenzymes, eight healthy dogs were placed under general anesthesia and 1 gm blocks were resected from selected muscles (intercostals, rectus abdominis, diaphragm, and sternothyroid) and from the walls of all four cardiac chambers. Each 1 gm block was homogenized individually in Ringer's lactate, centrifuged, and the supernatants were analyzed for total creatine kinase and lactate dehydrogenase activity by spectrophotometry. Isoenzymes were determined by agarose gel electrophoresis. The study shows that the chest wall muscles and atrial myocardium have appreciable quantities of creatine kinase MB. Hence, serum creatine kinase MB bands in the perioperative period can be generated by manipulation of chest wall muscles and the atrial wall as well as by infarction of the ventricular myocardium.

Animals↗

PubMed1993

Pathophysiological studies of neuromuscular function in subacute organophosphate poisoning induced by phosmet.

A 51 year old man developed progressive cranial and proximal muscle weakness, hyperreflexia and mental change. The disorder progressed over 9 days following the fifth weekly spraying with the organophosphate (OP) insecticide, phosmet, with limited symptoms of acute toxicity. Marked decremental responses of 50-80% on slow and fast rates of stimulation were improved to 15% by edrophonium or neostigmine. Intracellular recordings at the endplate region of intercostal muscle revealed small miniature endplate potentials (mepps), reduced mean acetylcholine sensitivity and normal membrane potentials. Electronmicroscopy revealed degeneration and regeneration of the endplates. This study demonstrates that OP poisoning due to phosmet can produce a subacute postsynaptic neuromuscular syndrome without marked symptoms of acute toxicity.

Critical Care↗

PubMed1992

Rib cage shape and motion in microgravity.

We studied the effect of microgravity (0 Gz) on the anteroposterior diameters of the upper (URC-AP) and lower (LRC-AP) rib cage, the transverse diameter of the lower rib cage (LRC-TR), and the xiphipubic distance and on the electromyographic (EMG) activity of the scalene and parasternal intercostal muscles in five normal subjects breathing quietly in the seated posture. Gastric pressure was also recorded in four subjects. At 0 Gz, end-expiratory LRC-AP and xiphipubic distance increased but LRC-TR invariably decreased, as did end-expiratory gastric pressure. No consistent effect was observed on tidal LRC-TR and xiphipubic displacements, but tidal changes in URC-AP and LRC-AP were reduced. Although scalene and parasternal phasic inspiratory EMG activity tended to decrease at 0 Gz, both muscle groups demonstrated an increase in tonic activity. We conclude that during brief periods of weightlessness 1) the rib cage at end expiration is displaced in the cranial direction and adopts a more circular shape, 2) the tidal expansion of the ventral rib cage is reduced, particularly in its upper portion, and 3) the scalenes and parasternal intercostals generally show a decrease in phasic inspiratory EMG activity and an increase in tonic activity.

Electromyography↗

PubMed2006

Respiratory dysfunction and management in spinal cord injury.

Respiratory dysfunction is a major cause of morbidity and mortality in spinal cord injury (SCI), which causes impairment of respiratory muscles, reduced vital capacity, ineffective cough, reduction in lung and chest wall compliance, and excess oxygen cost of breathing due to distortion of the respiratory system. Severely affected individuals may require assisted ventilation, which can cause problems with speech production. Appropriate candidates can sometimes be liberated from mechanical ventilation by phrenic-nerve pacing and pacing of the external intercostal muscles. Partial recovery of respiratory-muscle performance occurs spontaneously. The eventual vital capacity depends on the extent of spontaneous recovery, years since injury, smoking, a history of chest injury or surgery, and maximum inspiratory pressure. Also, respiratory-muscle training and abdominal binders improve performance of the respiratory muscles. For patients on long-term ventilation, speech production is difficult. Often, practitioners are reluctant to deflate the tracheostomy tube cuff to allow speech production. Yet cuff-deflation can be done safely. Standard ventilator settings produce poor speech quality. Recent studies demonstrated vast improvement with long inspiratory time and positive end-expiratory pressure. Abdominal binders improve speech quality in patients with phrenic-nerve pacers. Recent data show that the level and completeness of injury and older age at the time of injury may not be related directly to mortality in SCI, which suggests that the care of SCI has improved. The data indicate that independent predictors of all-cause mortality include diabetes mellitus, heart disease, cigarette smoking, and percent-of-predicted forced expiratory volume in the first second. An important clinical problem in SCI is weak cough, which causes retention of secretions during infections. Methods for secretion clearance include chest physical therapy, spontaneous cough, suctioning, cough assistance by forced compression of the abdomen ("quad cough"), and mechanical insufflation-exsufflation. Recently described but not yet available for general use is activation of the abdominal muscles via an epidural electrode placed at spinal cord level T9-L1.

Breathing Exercises↗

PubMed1996

Dystrophin expression in muscles of mdx mice after adenovirus-mediated in vivo gene transfer.

We have generated high-titer adenoviral recombinants (AVR) expressing a 6.3-kb partial dystrophin cDNA insert under the control of either the Rous sarcoma virus (RSV) or cytomegalovirus (CMV) promoter. These AVR preparations were free of both E1-containing AVR and AVR with a nonfunctional dystrophin expression cassette. With these optimal AVR preparations, we have obtained a high degree of short-term (10 days) expression of a truncated (approximately 200 kD) dystrophin in dystrophin-deficient mdx muscles injected in the neonatal period; a lesser degree of expression of dystrophin was found in muscles injected in the young adult age and in old animals. Microscopic indices of muscle damage revealed that the truncated dystrophin provided a significant protection of the transduced muscle fibers. However, by 60 days post-injection, a substantial reduction of the number of dystrophin-positive fibers was noted, even in the neonatally injected muscles, and near-total elimination of dystrophin-positive fibers occurred in muscles injected in the adult age. These effects appeared to be brought about by the activity of CD8+ cytotoxic lymphocytes directed against the transduced cells, leading to their eventual elimination. In severe combined immunodeficiency (SCID) mice, lacking both humoral and cellular immune competence, muscles transduced (either in the neonatal or adult age) by AVR containing a CMV-LacZ expression cassette maintained the early (10 day) transduction level up to 30 days post-injection. Systemic administration of AVR (i.e., into the left ventricle of the heart) led in 5 days to a high number of dystrophin-positive fibers in heart, diaphragm, and intercostal muscles but not in limb muscles.

Adenoviruses, Human↗

PubMed2005

Electromyographic monitoring of respiratory muscle activity in dyspneic infants and toddlers.

The aim of this study was to investigate whether the changes that occurred in the clinical asthma score (CAS) correlated with the changes in the respiratory electromyographic (EMG) activity over the days during admission to hospital in dyspneic infants and toddlers. Sixteen infants and toddlers (9 males) were studied during admission and 7 days after discharge. The CAS was used to assess the severity of dyspnea and consists of five items: respiration rate, wheezing, retractions, observed dyspnea, and inspiration-to-expiration ratio. Each item was scaled 0, 1, or 2, with a maximum score of 10. Electrical activity from the diaphragm (di) and intercostal muscles (int) was derived from surface electrodes. The logarithm of the EMG-Activity-Ratio (log EMGAR; ratio of mean peak-to-bottom EMG activity during admission to the hospital, to that at baseline, 7 days after discharge) was used as EMG parameter. For assessing the association between the repeated observations of the CAS and the EMG measurements we used the quantity r2 obtained with analysis of covariance. On the day of admission the patients had a mean CAS of 5.9 +/- 1.2. On the day of discharge the mean CAS decreased significantly to 2.1 +/- 1.6, indicating that the CAS returned to normal values. In line with this observation, a significant decrease in the log EMGARdi and log EMGARint was observed during the stay in the hospital. Over all subjects the correlation coefficient (r) of log EMGARdi versus CAS was 0.71, log EMGARint versus CAS was 0.67, and the mean log EMGAR versus CAS was 0.75 (p < 0.01, for all values). The correlation coefficients of subjects of < or = 1 year seemed to be lower than those of subjects of > 1 year of age (p < 0.01) and female subjects showed higher correlation coefficients than males. This study showed a moderate, but significant, relationship between the changes that occurred in the CAS and the changes in respiratory EMG activity during admission to hospital in dyspneic infants and toddlers. Moreover, the correlation coefficients of the combined leads of the intercostals and diaphragm (mean log EMGAR) were higher than those of the separate leads. The EMG measurements would extend diagnostic possibilities and would provide an objective measure to evaluate the clinical course of the disease and the efficacy of therapy in infants and toddlers with recurrent wheezing disorders.

Analysis of Variance↗

PubMed1983

Dystrophy of the diaphragmatic muscles in adult Meuse-Rhine-Yssel cattle: electromyographical and histological findings.

Electromyographic investigation of diaphragmatic muscles of Meuse-Rhine-Yssel cattle revealed a significant decreased duration of action potentials, while the number of polyphasic potentials was increased in four of seven cows. Histologically, the diaphragmatic muscles in all cows were affected severely, as characterized by variation in size of individual fibers, abundant vacuolar and hyaline degeneration with occasional fragmentation and phagocytosis, fiber splitting, apparent increase in internal nuclei, vesicular nuclei, chains of central nuclei, absence of regeneration, and proliferation of endomysial and perimysial connective tissue. Core-like structures seemed to be a hallmark of the disease. The intercostal muscles in all cows had core-like structures and some variation in fiber size; degenerative lesions did occur, but were less severe than in diaphragmatic muscles. In other skeletal muscles and cardiac muscles, core-like structures were present predominantly, indicating a generalized muscle disorder. No lesions were detected in the peripheral or central nervous systems. The muscular alterations were classified as a progressive muscular dystrophy, with a suspicion of hereditary transmission. This dystrophy may be an important animal model.

Animals↗

PubMed1987

Effect of lung autotransplantation on breathing regulation. Studies in dogs.

The effect of autotransplantation of the left lung on respiratory regulation was studied in four dogs in pentobarbital anaesthesia. In each dog the electrical and mechanical activity of the inspiratory muscles was studied before and 4-6 weeks, 3, 6 and 12 months after the transplantation. No or very little change was found in comparisons of spontaneous respiration or response to inhalation of carbon dioxide, hypoxia or combined hypercapnia and hypoxia. When the airways were closed after inflation with varying volumes of air, the increase in number and frequency of the electromyographic impulses in the intercostal muscles and the diaphragm (compared with the preceding unobstructed breaths) was greater before than after the lung autotransplantation. The duration of the first respiratory cycle after airway closure increased progressively with the volume of inflation in intact dogs and in dogs with autotransplanted left lung, though the increase was approximately halved following autotransplantation.

Animals↗

PubMed1981

Respiratory responses in reversible diaphragm paralysis.

The effects of diaphragm paralysis on respiratory activity were assessed in 13 anesthetized, spontaneously breathing dogs studied in the supine position. Transient diaphragmatic paralysis was induced by bilateral phrenic nerve cooling. Respiratory activity was assessed from measurements of ventilation and from the moving time averages of electrical activity recorded from the intercostal muscles and the central end of the fifth cervical root of the phrenic nerve. The degree of diaphragm paralysis was evaluated from changes in transdiaphragmatic pressure and reflected in rib cage and abdominal displacements. Animals were studied both before and after vagotomy breathing O2, 3.5% CO2 in O2, or 7% CO2 in O2. In dogs with intact vagi, both peak and rate of rise of phrenic and inspiratory intercostal electrical activity increased progressively as transdiaphragmatic pressure fell. Tidal volume decreased and breathing frequency increased as a result of a shortening in expiratory time. Inspiratory time and ventilation were unchanged by diaphragm paralysis. These findings were the same whether O2 or CO2 in O2 was breathed. After vagotomy, no significant change in phrenic or inspiratory intercostal activity occurred with diaphragm paralysis in spite of increased arterial CO2 partial pressure. Ventilation and tidal volume decreased significantly, and respiratory timing was unchanged. These results suggest that mechanisms mediated by the vagus nerves account for the compensatory increase in respiratory electrical activity during transient diaphragm paralysis. That inspiratory time is unchanged by diaphragm paralysis whereas the rate or rise of phrenic nerve activity increases suggest that reflexes other than the Hering-Breuer reflex contribute to the increased respiratory response.

Animals↗

PubMed2000

Antimyotonic effects of tocainide enantiomers on skeletal muscle fibers of congenitally myotonic goats.

Tocainide is effective in the symptomatic treatment of myotonic syndromes for its ability to reduce the high frequency discharges of action potentials typical of the disease, by blocking voltage-gated sodium channels. However, its use is restricted by serious side effects. In spite of its chiral structure, tocainide is clinically used as a racemic mixture. Since the optical isomers may differ in their efficacy and toxicity, the present study was aimed at evaluating the antimyotonic activity of the pure R(-) and S(+) enantiomers of tocainide, on the abnormal membrane hyperexcitability of external intercostal muscle fibers of congenitally myotonic goats. The excitability parameters were recorded in vitro by means of the standard two-microelectrode current-clamp technique before and after the addition of the compounds. The R(-) enantiomer of tocainide at concentrations as low as 10 microM potently counteracted the abnormal excitability of myotonic fibers, by increasing the threshold current, and decreasing the latency of the action potential and firing capability. Also, this concentration of R-(-) tocainide almost completely abolished the abnormal spontaneous electrical activity occurring in about 70-80% of the myotonic fiber. The S(+) enantiomer was remarkably less potent since up to 100 microM did not restore the normal excitability pattern. The results show that most of the antimyotonic activity of tocainide resides in the R(-) enantiomer suggesting that its clinical use may allow a significant reduction of the doses and possibly of the side effects.

Animals↗

PubMed2000

[Muscle hydatidosis. 15 cases].

OBJECTIVES: The aim of this study was to analyse the epidemiological, diagnostic and therapeutic aspects of muscle hydatidosis. PATIENTS AND METHODS: This retrospective study included a series of 15 patients with hydatic muscular cysts operated on in our service over an eight year period. Five cysts were superficial and ten were deep. Patients were predominantly young adults (10 cases); M/F sex ratio was 2/1. Clinical signs included atypical pain, particularly for the deep localizations, and tumoral formations, particularly for superficial localizations. Diagnosis of muscle hydatidosis was made in some patients seen for complications or systematic search for another localization. A second hepatic localization was found in 5 cases and a splenic localization in one. Sonography provided the diagnosis in all cases although the exact localization could not be determined. A CT scan was performed in half the cases. Localizations included the diaphragm 7 cases, psoas 3 cases, and buttock, triceps, sartorius, anterior tibial and intercostal muscles 1 case each. RESULTS: Surgical treatment was the same for all abdominal localizations, although different access routes were used. Partial pericystostomy was the basic procedure and gave excellent results. One case was complicated by a crural nerve lesion that recovered spontaneously. Recurrence in the diaphragm occurred in two cases and was successfully treated surgically two years later. One patient died due to acute liver failure subsequent to multiple cysts which had destroyed the entire liver.

Adult↗

PubMed1994

The effects of oesophageal distension on diaphragm and laryngeal muscle activity in the anaesthetized cat.

The electromyographic (EMG) activities of diaphragm and laryngeal muscles were recorded during oesophageal distension in anesthetized cats. The responses to distension of the thoracic oesophagus differed from those evoked by distension of the cervical oesophagus. The crural component of the diaphragm (CD) was inhibited by distension of the thoracic oesophagus; distension of the cervical oesophagus did not affect CD EMG. Thyroarytenoid (TA) muscle EMG increased markedly and consistently in response to distension of the cervical oesophagus. Distension of the thoracic oesophagus only produced statistically significant increases in TA EMG with high distending volume (10 ml) at the level of the gastro-oesophageal junction. The main abductor of the vocal cords, the posterior cricoarytenoid (PCA) was either unchanged or decreased by oesophageal distension. The electrical activities of left paratendinous diaphragm, left costal diaphragm, internal intercostal and external intercostal muscles remained unchanged. The entire pattern would appear to constitute a means to aid passage of a bolus into the stomach, and simultaneously guard the respiratory tract from reflux or aspiration.

Anesthesia↗

PubMed1985

Early bronchial revascularization with an intercostal pedicle graft following canine lung autotransplantation.

The contribution of an intercostal pedicle flap to early revascularization and healing of the bronchial anastomosis following lung autotransplantation was evaluated in dogs. Left lung reimplantation was performed both in 33 control dogs (group 1) and in 38 dogs in which a pedicled intercostal muscle graft was wrapped around the bronchial anastomosis (group 2). Radiologic injection studies, estimation of the cross-sectional area of the anastomosis and histologic examination to assess the degree of healing were made at autopsy - 7, 14 and 28 days respectively after transplantation. Within a week, the bronchial mucosa was more normal and the anastomosis substantially more patent in group 2 than in group 1 animals. This study indicates that the intercostal pedicle flap significantly improves bronchial healing by promoting revascularization across and beyond the bronchial anastomosis at least as early as 7 days after lung reimplantation.

Animals↗

PubMed1997

A novel muscle sodium channel mutation causes painful congenital myotonia.

Mutations in the skeletal muscle voltage-gated sodium channel alpha-subunit gene (SCN4A) have been associated with a spectrum of inherited nondystrophic myotonias and periodic paralyses. Most disease-associated SCN4A alleles occur in portions of the gene that encode the third and fourth repeat domains with the conspicuous absence of mutations in domain 1. Here we describe a family segregating an unusual autosomal dominant congenital myotonia associated with debilitating pain especially severe in the intercostal muscles. A novel SCN4A mutation causing the replacement of Val445 in the sixth transmembrane segment of domain 1 with methionine was discovered in all affected individuals and is the likely genetic basis for the syndrome. Myotonia was resistant to treatment; however, the most severely affected family member responded dramatically to the sodium channel blocking agent flecainide.

Alleles↗

PubMed1992

Pulmonary function and resting breathing pattern in myotonic dystrophy.

In 17 patients with myotonic dystrophy, spirometric, flow-volume, and maximal mouth occlusion variables were obtained and compared with 8 normal subjects. Ventilatory CO2 response was measured by the estimation of the steady-state effect of a sufficiently large serial dead space. Variability of resting breathing pattern was expressed by the variation coefficients of respiratory cycle time and tidal volume. The group means of the total lung capacity (TLC), vital capacity (VC), forced expiratory volume in 1 sec (FEV)1 and forced inspiratory volume in 1 sec (FIV)1 showed a restrictive pattern. Only maximal static mouth pressure (Pi,max), measured at residual volume (RV) level, showed a significant positive correlation with both VC (p = 0.03) and FIV1 (p = 0.02), suggesting inspiratory muscle weakness as a determinant of the restriction. Although the differences were just not significant, both variation coefficients of the respiratory cycle time and tidal volume were larger in the group with a CO2 sensitivity below the lower limit of normal compared to those with a normal ventilatory response to CO2. In 3 patients, fluctuations in FRC were also present. We hypothesize that, in addition to the already documented FRC fluctuations by uncoordinated spontaneous intercostal muscle action, a defect of integration of afferent neural input and chemical drive in the medullary region may also be present in these patients.

Adult↗

PubMed1985

Reflex compensation of voluntary inspiration when immersion changes diaphragm length.

When immersion alters inspiratory muscle operating lengths, spontaneously breathing humans maintain a constant tidal volume by reflex adjustment of inspiratory muscle activation (Reid et al. J. Appl. Physiol. 58: 1136-1142, 1985). We term this the operational length compensation reflex. The present experiment demonstrates that similar adjustments occur during voluntary respiratory maneuvers. Each of seven naive subjects sat in a tank with water at hip level. We trained them to reproduce an inspired volume (+/- 10%) at constant inspiratory duration. They received verbal feedback during training but not during the experiment. We measured surface electromyograms (EMGs) of diaphragm and intercostal muscles and tidal volume. After the subjects were trained, we made repeated measurements of 10 trained breaths with water at the hip and then again after raising water level to the xiphoid (which decreases lung volume and increases operating length of the diaphragm). In 30 of 42 trials there was a substantial fall in peak diaphragm EMG. In 10 trials this was sufficient to prevent any change in tidal volume. Inspiratory flow was more closely regulated than tidal volume. Subjects were not aware of making adjustments in drive.

Adult↗

PubMed1980

The acetylcholine channel open time in chick muscle is not decreased following innervation.

1. The mean channel open time (tau) of ACh receptors was measured in chick muscles at various stages of development. Tau was estimated by analysing ACh induced current fluctuations recorded extracellularly from small (ca. 20 micrometers2) membrane patches. 2. At random sites on uninnervated, embryonic chick muscle fibres in vitro, tau was relatively long--4 msec at 23 degrees C. 3. Estimates of tau at synaptic sites on embryonic myotubes innervated in vitro were identical to estimates at extrasynaptic sites on the same fibres. Both were comparable to estimates on uninnervated myotubes. 4. Synaptic currents at cultured junctions decayed slowly as simple exponentials. The decay time constants were never shorter than the mean channel open time measured by fluctuation analysis. 5. In anterior latissimus dorsi and intercostal muscle fibres of 4- to 18-week posthatched chicks, fluctuation analysis and synaptic current decays indicate that the channel open time of mature chick endplate receptors is as long as that of embryonic synaptic receptors in vitro. Apparently, tau remains prolonged throughout the maturation of chick neuromuscular junctions.

Acetylcholine↗

PubMed1987

Thoracoplasty: its forgotten role in the management of nontuberculous postpneumonectomy empyema.

The role of thoracoplasty in the management of empyema complicating pneumonectomy is controversial because alternative techniques, such as pedicled muscle transplants or open-space sterilization, have now replaced the conventional collapse procedures. Among 46 patients treated for postpneumonectomy empyema during the years 1975 to 1984, 17 underwent space-reducing thoracoplasty as the final step in pleural space management. Technical considerations, critical in the success of the operation, were: (a) single-stage extramusculoperiosteal resection of the second to the seventh rib, (b) sparing of the first rib to maintain integrity of the neck and shoulder girdle, (c) intercostal muscle closure of large fistulas and (d) adequate drainage of pleural and extrapleural spaces. Immediate control of the empyema was obtained in 15 (88%) patients. Fourteen patients were alive at the time of follow-up (mean 4.5 years) and none had major thoracic deformity or residual infection. Our data show that thoracoplasty is an excellent therapeutic option for patients with chronic postpneumonectomy empyema. Adherence to strict surgical principles ensures that the space is obliterated and the cosmetic result is satisfactory.

Adult↗