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At least 721 records · Page 40Linked to original sources
PubMed2000

Transgenic mice reveal novel sites of calcitonin receptor gene expression during development.

To characterize the tissue and developmental-specific transcriptional activity of the human calcitonin receptor (hCTR) gene in vivo, transgenic mice containing a 4.9-kb hCTR promoter/beta-galactosidase (lacZ) construct were generated. Between 8.5 and 10.5 days of development, lacZ-positive cells were observed on the lateral side of cervical and occipital level somites and in the lateral myotome. LacZ-positive cells also appeared to be migrating from the dermomyotome into the adjacent limb buds, suggesting that the hCTR promoter is active in hypaxial muscle progenitors. By 11.5-16 days of development, novel hCTR expression sites were identified that included limb buds, cornea, retina, skin, intercostal muscles, muscles of the limbs, face, and dorsal root ganglion. hCTR promoter activity in a number of these tissues was repressed at adult stages of development. RT-PCR demonstrated endogenous mCTR mRNA in all lacZ-positive tissues assayed. The developmental regulation of hCTR gene expression in the above tissues suggests that CTRs are likely to play an important role in their morphogenesis.

Animals↗
PubMed1986

Anesthetic effects on [H+]a and muscle metabolites at rest and following exercise.

We determined the effects of ether, intra-arterial Na+ pentobarbital (SP) and decapitation on arterial [H+] and labile metabolites in plantaris, diaphragm and intercostal muscles of rats at rest and following exhaustive treadmill exercise. 30-60 sec post-analgesia arterial [Lactate] ([LA]a) increased with both anesthetics. SP rats retained CO2 resulting in mixed acidosis, while ether anesthetized rats hyperventilated and maintained pH. During recovery from exercise ether anesthesia had no effect but SP anesthesia caused CO2 retention. Decapitation of resting rats markedly decreased [CP] and elevated [LA] and [G6P] in all three muscles, thereby negating any subsequent exercise effects. The effects of ether differed from those of SP in that with ether anesthesia: [CP]/[Total Creatine] fell and [LA] rose significantly with exercise; resting [LA] was lower and increased with exercise; and metabolite variability was less with ether than with SP. We conclude that: anesthesia obscured the true effects of exercise on acid-base status by increasing [LA]a in the resting state; decapitation is unsuitable for the study of exercise effects on most muscle metabolites; ether anesthesia is most suitable for use in studies aimed at detecting exercise effects on muscle metabolites and for preserving arterial acid-base status closest to the unanesthetized state.

Acid-Base Equilibrium↗
PubMed1998

Projections of the caudal ventrolateral medulla to the thoracic spinal cord in the rat.

BACKGROUND: The caudal ventrolateral medulla (CVLM), an area having cardiovascular and respiratory functions, contains neurons that project to the thoracic spinal cord. It has been presumed, although never demonstrated, that the CVLM thoracic projections terminate on intercostal and sympathetic motor neurons. Using a combination of tracers, the purpose of the present study was to describe a route through which the CVLM may directly influence sympathetic and intercostal motor neurons. METHODS: To label the medullospinal projections orthogradely, either biotinylated dextran amine or lectin conjugated horseradish peroxidase was injected into the CVLM. To label the intercostal and sympathetic motor neurons retrogradely, cholera toxin subunit B-horseradish peroxidase was injected into the intercostal muscles and superior cervical ganglion. Subsequently, projections from the CVLM were observed to terminate on, or in close proximity to, sympathetic and intercostal motor neurons. RESULTS: Projections to sympathetic neurons were largely ipsilateral, whereas projections to intercostal neurons were primarily contralateral. In retrograde labeling experiments, it was observed that many of the CVLM-thoracic projections originated from the nucleus retroambiguus. CONCLUSIONS: The finding that the CVLM projects to sympathetic and intercostal motor neurons supports its role in cardiovascular and respiratory functions. The authors suggest that CVLM influences upon sympathetic motor neurons may be inhibitory.

Animals↗
PubMed1990

Schwartz-Jampel syndrome: I. Clinical, electromyographic, and histologic studies.

In a new, typical case of Schwartz-Jampel syndrome (SJS) the origin of the disorder was found to be purely myogenic. Concentric needle EMG showed abundant and persistent spontaneous activity, maximal at insertion, and uninfluenced by local curarization. Single-fiber EMG showed rather stable, sometimes intermittent, discharge series with occasional amplitude and/or frequency fluctuations. It could be demonstrated that this activity did not consist of complex repetitive discharges, but of independent activity of individual muscle fibers. This contrasts with findings by other investigators that have been published in this journal. Light microscopic studies of quadriceps and intercostal muscles showed no abnormalities, whereas electron-microscopic findings were in accordance with earlier studies in SJS. Endplate analysis revealed no specific changes; the postsynaptic structures gave the impression of an accelerated-maturation.

Abnormalities, Multiple↗
PubMed1992

Open-window thoracostomy in pleural empyema.

Open-window thoracostomy (OWT) was performed in 21 cases of empyema. The indications were postpneumonectomy empyema with (n = 6) or without (n = 1) fistula, early recurrent empyema after decortication (n = 6), chronical empyema in ill elderly patients with (n = 5) or without fistula (n = 2), and total unilateral lung gangrene with a large fistula of the main bronchus after radiotherapy and chemotherapy (n = 1). All cases presented with severe sepsis, eight of them with acute septic shock, and six with signs of multiorgan failure. Three to five ribs were resected, the muscles and skin were sutured to the ribs confining the window located at the lowest point of the empyema cavity, while the intercostal muscles of the resected ribs were used to close fistulae. The cavity was packed with dressings every day. In all cases, the sepsis subsided immediately after OWT. With the exception of one patient with postpneumonectomy empyema, who died of contralateral pneumonia on day 36, no surgery-related complications were seen. Four further patients died of unrelated causes 2, 4, 5, and 7 months, respectively, after OWT. In one of them, the OWT had been closed. Up to this time, obliteration and closure of the cavity has been carried out in 7 cases by using thoracoplasty (n = 2) or predicted muscle flaps (n = 5) either in the early course or after a delay of 11 to 23 months, with fair functional and cosmetic results. In one further case, operative closure has been planned. In seven of the eight remaining patients, four of whom declined further operations, the cavities closed spontaneously, despite their initial size after intervals of between 11 and 21 months.

Adult↗
PubMed1986

Comparative effects of the ionophore A23187 on the mechanical responses of muscle in normal Pietrain pigs and pigs with malignant hyperthermia.

Since increased intracellular Ca2+ is believed to be the main factor causing skeletal muscle contracture in human and porcine malignant hyperthermia, the potential effects of the ionophore A23187, which enhances intracytoplasmic Ca2+, were investigated in Pietrain pig muscles. These effects were compared with those of caffeine, known to induce dose-dependent contracture in vitro in isolated muscle from human subjects with malignant hyperthermia. For this purpose, the mechanical and biochemical actions of caffeine and A23187 were tested in intercostal muscle biopsies from 10 normal pigs and 10 with malignant hyperthermia. The results show that A23187 allowed very clear differentiation between the muscles of normal and pathological animals. In view of the wide spectrum of drug sensitivity characterizing subjects with malignant hyperthermia, it is suggested that exposure to A23187 be added to the halothane and caffeine tests currently used to detect this disease.

Animals↗
PubMedDate not supplied

[Change in the histamine and serotonin levels in the external respiratory apparatus in botulinic poisoning in cats].

General botulinic intoxication in cats, accompanied by severe respiratory insufficiency, was characterized by distinct impairments in histamine and serotonin metabolism in external respiratory system. Pronounced increase in content of histamine was observed in impaired muscles and their corresponding regional centers of medulla spinalis, when botulinic intoxication had the local type with unilateral paralysis of diaphragm and intercostal muscles. Content of serotonin was increased in the tissues studied only at the later steps of local botulinic intoxication.

Animals↗
PubMed1989

Intercostal and abdominal muscle afferent influence on caudal medullary expiratory neurons that drive abdominal muscles.

Our objective was to determine if caudal ventral respiratory group (VRG) expiratory (E) neurons that drive abdominal expiratory motoneurons in the lumbar cord respond to intercostal and lumbar nerve afferent stimulation. Results showed that 92% of medullary E-neurons that were antidromically activated from the upper lumbar cord reduced their activity in response to stimulation of external and internal intercostal and lumbar nerve afferents. We conclude that afferent information from intercostal and abdominal muscle tendon organs has an inhibitory effect on caudal VRG E-neurons that drive abdominal expiratory motoneurons.

Abdominal Muscles↗
PubMed1993

Comparison of several oximes on reactivation of soman-inhibited blood, brain and tissue cholinesterase activity in rats.

The ability of three oximes, HI-6, MMB-4 and ICD-467, to reactivate cholinesterase (ChE) inhibited by the organophosphorus compound soman was compared in blood (plasma and erythrocytes), brain regions (including spinal cord) and peripheral tissues of rats. Animals were intoxicated with soman (100 micrograms/kg, SC; equivalent to 0.9 x LD50 dose) and treated 1 min later with one of these oximes (100 or 200 mumol/kg, IM). Toxic sign scores and total tissue ChE activities were determined 30 min later. Soman markedly inhibited ChE activity in blood (93-96%), brain regions (ranging from 78% to 95%), and all peripheral tissues (ranging from 48.9% to 99.8%) except liver (11.9%). In blood, treatment with HI-6 or ICD-467 resulted in significant reactivation of soman-inhibited ChE. In contrast, MMB-4 was completely ineffective. HI-6 and ICD-467 were equally effective at the high dose. At the low dose ICD-467 treatment resulted in significantly higher plasma ChE than HI-6 treatment, whereas HI-6 treatment resulted in higher erythrocyte ChE than ICD-467 treatment. However, none of these three oximes reactivated or protected soman-inhibited ChE in the brain. In all peripheral tissues (except liver) studied, MMB-4 was not effective. HI-6 reactivated soman-inhibited ChE in all tissues except lung, heart, and skeletal muscle. ICD-467 was highly effective in reactivating ChE in all tissues and afforded a complete recovery of ChE to control levels in intercostal muscle and salivary gland. Oxime treatments did not modify the toxic scores produced by soman. However, treatment with the high dose (200 mumol/kg) of ICD-467 depressed respiration and two of the six rats died in 10 min. These observations indicate that MMB-4 is completely ineffective in protecting and/or reactivating soman-inhibited ChE, HI-6 is an effective ChE reactivator as reported earlier in rats and other species, and the imidazolium oxime ICD-467 is a powerful reactivator of soman-inhibited ChE; however, its toxic interactions with soman may not be related to tissue ChE levels.

Animals↗
PubMed1995

The cost of breathing in stable chronic obstructive pulmonary disease.

1. The hypermetabolism frequently observed at rest in patients with chronic obstructive pulmonary disease has been attributed to a high cost of breathing. However, measurement of the cost of breathing by the usual hyperventilation procedure is fraught with methodological problems. The purpose of this study was to measure more directly the cost of breathing in a group of ambulatory patients with stable chronic obstructive pulmonary disease. 2. The cost of breathing was calculated as the difference in oxygen consumption measured by indirect calorimetry between spontaneous breathing and noninvasive mechanical ventilation. Inspiratory muscle rest was achieved by negative or positive pressure ventilation and assessed by the recording of surface electromyograms of the diaphragm and parasternal intercostal muscles. 3. Seven tests were performed in six ambulatory patients with stable chronic obstructive pulmonary disease, four tests using positive pressure ventilation and three with negative pressure ventilation. During mechanical ventilation, the electromyographic activity of the diaphragm decreased by 70 +/- 22%, while that of the parasternals was suppressed in four tests, and remained unchanged in three. However, oxygen consumption was only 1.6 +/- 6.2% lower during mechanical ventilation. 4. The cost of breathing measured in this study was therefore much lower than previously published values. Stress was not likely to influence the results, as both the heart rate and plasma catecholamines did not change between spontaneous breathing and mechanical ventilation. These results suggest that the cost of breathing in ambulatory patients with stable chronic obstructive pulmonary disease may be lower than previously estimated.

Aged↗
PubMed1995

Acute electrical burns.

Electric current can damage an individual by thermal heating of the tissues; by disregulating autonomously functioning organ systems, such as the circulatory and respiratory systems; or by once-only or continuing stimulation of the nerves and striated muscles. In the first case, the result is coagulation necrosis, and in the second case life-threatening events can occur, such as arrhythmia or apnea. In the third case, vigorous nerve stimulation can lead to paralysis and vasospasm. Massive muscle contractions due to nerve stimulation or the direct triggering of striated muscles can cause ruptures, ligamentous tears, fractures, and joint dislocations, while prolonged current passing through the thoracic wall may stimulate tetany of the intercostal muscles and diaphragm resulting in asphyxia. This article is confined to a description of thermal or Joule heating of tissues when they form part of an electric circuit and to the effects of direct nerve and muscle stimulation. Other articles discuss nonthermal effects. The injuries a person sustains as the result of an electrical accident depend on a large number of interrelated factors, such as the properties of the electrical power supply, the magnitude and duration of current flow, the current pathway, and skin conditions. It makes a vast difference whether a person is hit by a lightning bolt (extremely high voltage, short current flow) or receives a shock from an electrical power supply (low to high voltage, relatively long current flow). Wide variation in the physical properties of lightning discharges and the discharges from electrical power supplies at home and in industry means that all kinds of injuries can be encountered.

Acute Disease↗
PubMed1981

Tracheo-oesophageal fistula caused by cuffed tracheal tubes.

Two patients with tracheo-oesophageal fistula following endotracheal intubation and tracheostomy are reported. In both cases the fistulas were related to inflammation of the cuffs distal to the tracheostomy. Two kinds of surgical treatment were performed: (1) Resection of 3 cm of the cervical trachea, closure of the oesophageal fistula opening with absorbable sutures and interposing a muscle flap of the left sternohyoid muscle. (2) No resection of the trachea. Direct closure of the fistula openings, and interposition with fixation to the trachea of a vascularized intercostal muscle flap via a right-sided thoracotomy. For optimal results of surgery, the pre-operative requirements should include control of septicaemia and gastrobronchial regurgitation, establishment of spontaneous ventilation and correction of malnutrition. For these purposes, the gastrostomy and transgastric jejunostomy regime was important in our patients. The simultaneous use of tracheal and oesophagus tubes is considered a risk factor in development of tracheobronchial fistulas.

Adult↗
PubMed2002

Preliminary findings in the neurophysiological assessment of intercostal nerve injury during thoracotomy.

OBJECTIVE: Previous work has suggested that intercostal nerve injury is a major factor in the aetiology of chronic post-thoracotomy pain. The aim of this study was to establish if there was identifiable intercostal nerve injury during thoracotomy. METHODS: Intercostal nerves were stimulated and motor evoked potentials were recorded from intercostal muscles in 13 patients undergoing thoracotomy. Measurements were taken before and after entering the pleural space, after removal of the rib retractor and after intercostal space closure. RESULTS: Intercostal nerves functioned normally before and after entering the pleural space. After the rib retractor was removed, there was a total conduction block in the nerve immediately above the incision in every patient. In the nerves above this, six had a total block, one a partial block and three had normal conduction. There was a total conduction block in the nerve immediately below the incision in all but one patient. Of the nerves below this, four had a total block, two a partial block and three had normal conduction. In the cases of total conduction block, there was either a discrete block at the level of the distal end of the rib retractor or impairment throughout the whole nerve. Intercostal space closure did not injure any previously uninjured nerve. In a solitary patient where rib retraction was not employed, there was no impairment of the intercostal nerves throughout the operation. CONCLUSIONS: This study demonstrates for the first time that intercostal nerve injury occurs routinely due to rib retraction during thoracotomy. We believe that it may be an important step toward understanding the cause of post-thoracotomy neuralgia.

Evoked Potentials, Motor↗
PubMed2006

Impact of post-synaptic block of neuromuscular transmission, muscle unloading and mechanical ventilation on skeletal muscle protein and mRNA expression.

To analyse mechanisms of muscle wasting in intensive care unit patients, we developed an experimental model where rats were pharmacologically paralysed by post-synaptic block of neuromuscular transmission (NMB) and mechanically ventilated for 9+/-2 days. Specific interest was focused on the effects on protein and mRNA expression of sarcomeric proteins, i.e., myosin heavy chain (MyHC), actin, myosin-binding protein C (MyBP-C) and myosin-binding protein H (MyBP-H) in fast- and slow-twitch limb, respiratory and masticatory muscles. Muscle-specific differences were observed in response to NMB at both the protein and mRNA levels. At the protein level, a decreased MyHC-to-actin ratio was observed in all muscles excluding the diaphragm, whereas at the mRNA level a decreased expression of the dominating MyHC isoform(s) was observed in the hind limb and intercostal muscles, but not in the diaphragm and masseter muscles. MyBP-C mRNA expression was decreased in the limb muscles, but it otherwise remained unaffected. MyBP-H conversely increased in all muscles. Furthermore, we found myofibrillar protein and mRNA expression to be affected differently when comparing NMB animals with peripherally denervated (DEN) ambulatory rats. We report that NMB has both a larger and different impact on muscle, at the protein and mRNA levels, than DEN has.

Animals↗
PubMed1991

Pectus excavatum: a 15-year perspective.

Pectus excavatum is relatively uncommon. Our experience with 177 children during a 15-year period produced changes in our surgical technique, which now includes a small transverse incision, minimal subcutaneous flap elevation, a muscle-relaxing incision over the fifth costal cartilage, complete resection of involved cartilage, use of Adkins' strut, suspension of sternum to strut, taut reefing of intercostal muscle, no tubes or drains, epidural analgesia, a patient-controlled analgesia device postoperatively, and eventual strut removal. Use of the evolved technique gives excellent cosmetic results, good functional results with minimal discomfort, and a shorter convalescent period.

Adolescent↗
PubMed1976

Respiratory load compensation in infants.

We have studied the respiratory compensation for elastic loads in 15 term and preterm infants. Elastic loads, approximately equal to the infant's effective elastance, were applied to the airway for five breaths while tidal volume and mask pressure were monitored. Motion of the rib cage and abdomen were monitored simultaneously with magnetometers. The studies were done both in active or REM sleep and in quiet or non-REM sleep. During quiet sleep the load immediately reduced the tidal volume by about 50% but a progressive increase in tidal volume occurred over the next four loaded breaths. During active sleep load compensation was disorganized with respect to both tidal volume and frequency, and compensation was significantly less. Active sleep was also characterized by marked rib cage distortion. We suggest that during active sleep there is tonic inhibition of the intercostal muscles, allowing the diaphragm to distort the rib cage. This distortion impairs load compensation by a direct mechanical effect and indirectly by initiating an intercostal-phrenic reflex.

Abdomen↗
PubMed1998

[Response of respiratory muscles to microinjections of acetylcholine and propranolol into the rat solitary nucleus].

Unilateral microinjections of acetylcholine into the rat solitary tract nucleus evoked inhibitory effects in electrical activity of symmetrical portions of the diaphragm and external intercostal muscles. Administration of propranolol exerted excitatory respiratory responses. The findings suggest participation of cholin- and noradrenergic systems in inhibitory mechanisms of respiratory control. Different roles of the right and left solitary tract nuclei in their involvement in formation of efferent impulses to bilateral inspiratory muscles, are discussed.

Acetylcholine↗
PubMed1985

Projections from the ventral respiratory group to phrenic and intercostal motoneurons in cat: an autoradiographic study.

Anterograde transport of tritiated amino acids (leucine, lysine, and proline) was used to examine the spinal projections of respiratory premotor neurons in the ventral respiratory group (VRG) of cats. This population of neurons corresponds anatomically with the nucleus ambiguus-retroambigualis. Small volumes (20 to 50 nl) of tritiated amino acids were pressure ejected into the middle of the VRG through a micropipette which permitted simultaneous recording of respiratory modulated activity. In two cats injections were made caudal to the obex in regions which contained expiratory modulated neurons. In five cats injections were made rostral to the obex in regions containing inspiratory neurons. After a 2-week survival period, cats were anesthetized and perfused. The entire neuraxis was removed and processed using standard autoradiographic techniques. Transport of tritiated amino acids revealed a marked bilateral projection to lamina IX of the spinal cord at the C4 to C6 level and a primarily contralateral projection to laminae VIII and IX in the thoracic spinal cord. Distinct descending pathways to the phrenic motor neurons were observed in the lateral funiculus and in the ventral funiculus; descending fibers to the intercostal motoneurons in the thoracic cord appeared to be restricted to the ventral funiculus. Labeling of axon terminals in both the cervical and thoracic cords was confined to ventral horn regions which contain motoneurons. These results suggest that monosynaptic projections from brainstem bulbo-spinal neurons to spinal motoneurons are important in controlling respiratory movements of the diaphragm and intercostal muscles.

Animals↗