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At least 865 records · Page 48Linked to original sources
PubMed1984

Critical periods in rat motoneuron development.

Reinnervation of rat internal intercostal muscles was examined 2 weeks after intramuscular axotomy in the period embryonic Day 17 (E17) to postnatal Day 2 (PN2). The efficiency of reinnervation depended on the day of denervation. Responses to nerve stimulation were common only in muscles denervated in the interval E19-21. Functional reinnervation was seldom seen in muscles denervated earlier, and was absent in muscles denervated shortly after birth. We suggest that there are "critical periods" in the sequence of differentiation of motoneurons. At E17 these neurons are very susceptible to cell death and any that lose contact with their muscle will die. Motoneurons axotomized later, while motor unit size is still increasing, can regenerate some functional nerve-muscle junctions. Motor unit size reaches its maximum by E21 and if motoneurons are axotomized after that time, in neonates, they cannot form more synaptic terminals although they can still extend axons. During this early postnatal period motoneurons normally reduce their number of nerve-muscle contacts. Finally, at 3 weeks of age, motoneurons reach their adult state when they are capable of regeneration relatively unhindered by restrictions on the number and location of their peripheral connections.

Animals↗
PubMed1989

An aortic body carcinoma with multifocal thoracic metastases in a cat.

A necropsy performed on an aged cat with respiratory signs revealed a large white firm mass cranioventrally to the heart, and multiple similar masses scattered throughout the lungs, diaphragm, pericardial sac and intercostal muscles. The histological examination of the primary site and the metastases are consistent with a well-differentiated aortic body carcinoma.

Animals↗
PubMed1977

Surgical correction of pectus excavatum.

It has been observed that some patients who had correction of funnel chest deformity by methods which failed to provide fixed elevation of the involved sternal segment developed progressive sagging in later years in spite of looking good at the operating table. This has led to the adoption of a new technique of double sternal support. This procedure has resulted in 35 of 37 children (94%) being classified as excellent or satisfactory. This double support was initially established in 1959 by overlapping the upper transsected sternum while maintaining elevation of the lower end with a soft tissue sling of perichondrium and intercostal muscle. Beginning in 1961, a rigid bridge of rib or stainless steel bar was substituted at the lower end of the sternum. This has provided better support and the current preference of using the steel bar has been validated in this group of patients. The few disappointments were related to removal of the bar earlier than desired, failure to excise all the protruding sternal cartilage stumps or rib graft tips and inability to cover the lateral sternal edges with pectoral muscles. If possible, the steel bar should not be removed before 12 mo. When these pitfalls were avoided, the results were almost uniformly excellent. The wisdom of excising all depressed cartilaginous segments, as advocated by Ravitch in 1949, has been substantiated. A submammary transverse incision has provided an excellent cosmetic appearance. The morbidity has been low and the mortality zero. In spite of the absence of objective evidence of cardiopulmonary dysfunction, there seems to be an almost uniform improvement in appearance and in patient activity following successful correction of the funnel chest. The latter may be as much a psychological response as a physiologic one. The low morbidity, satisfactory long term results, and general improvement in the patient's body image and outlook on life indicate the need to offer correction of the severe pectus excavatum deformity to low risk children.

Adolescent↗
PubMed1991

Acquired tracheoesophageal fistula in infancy and childhood.

Acquired tracheoesophageal fistula (TEF) is a rare entity in the pediatric age group. We report two pediatric patients with acquired TEF caused by shells of pistachio nuts. In both patients the primary operation did not resolve the problem and a second intervention for recurrent fistula was needed. The special nature of acquired TEF, particularly the one described herein, requires delayed surgical intervention and meticulous separation of the respiratory and alimentary tracts by an intercostal muscle flap.

Child, Preschool↗
PubMed1988

Lambert-Eaton myasthenic syndrome: the lack of short-term in vitro effects of serum factors on neuromuscular transmission.

Serum was obtained from 7 patients with the Lambert-Eaton myasthenic syndrome (LES), 3 patients with small-cell carcinoma of the lung (SCCL), and 9 healthy control subjects. Serum samples were applied in vitro to the rat neuromuscular junction (for 1-3 h for control LES sera; 4 h for SCCL sera), following which the pre- and postjunctional physiological effects of serum factors were studied in the presence of 10 mM [Mg2+]o. All sera produced a marked reduction in the frequency of spontaneous miniature end-plate potentials (MEPPs), while causing slight to moderate changes in MEPP amplitude. There were no consistent changes in the quantum content of the impulse-evoked end-plate potentials, though the serum from one LES patient significantly and reversibly inhibited the evoked quantal release. No significant effect was found when a human intercostal muscle was exposed to serum from another LES patient for 2 h. Therefore, when applied in vitro on a short-term basis, the putative LES autoantibodies do not consistently react with voltage-dependent calcium channels in the motor nerve terminal and thus fail to reproduce the physiologic abnormality of the syndrome. We suggest that the pathogenic IgG molecules may require more than 3h of incubation in order to gain access to, and inhibit the function of, the prejunctional Ca2+ channels.

Action Potentials↗
PubMed1990

Morphological changes in the human end plate with age.

We carried out a light and electron microscopic study on end plates and related structures in external intercostal muscles from subjects aged between 4 and 77 years. Light microscopically end plates maintained the same size, did not increase in number and showed no sprouting of terminal axons, all indicating that major compensatory histological changes to maintain adequate neuromuscular transmission with age were not required. At the ultrastructural level end plates became more complex mainly at the postsynaptic side. The latter included increased length and branching of the postsynaptic membrane with enlargement of the postsynaptic area, and degeneration of junctional folds. However, some neuromuscular junctions (NMJs) showed little branching of the postsynaptic membrane, even in old age. At the presynaptic side nerve terminals with an irregular shape were noted in the aged. Schwann cell processes were seen to intrude into the primary synaptic cleft. From these data we suggest that degeneration of the postsynaptic membrane with consequent focal denervation of NMJs is a primary event in the age-related changes of end plates. The muscle fibres showed a minor degree of type grouping in old age doubtless due to loss of motor neurons with age.

Adult↗
PubMed1985

Peripheral circulatory responses to 96 hours of eucapnic hypoxia in conscious sheep.

Conscious sheep acclimatizing to hypoxia (PaO2 40 mm Hg, PaCO2 24 mm Hg) respond with increases in cardiac output (Qco) and cerebral blood flow lasting for 24 and 48 h, respectively. Coronary flow increases in a sustained fashion, while there are progressive decreases in renal, splenic and pancreatic flows. In the present study, 5 adult ewes were exposed to similar levels of normobaric hypoxia (PaO2 40 mm Hg) but the PaCO2 was maintained at eucapnic levels (32 mm Hg). VE increased (+210%) while VO2 decreased by 35%. Ventilatory sensitivity to CO2 was unchanged. Qco (thermodilution) was elevated for 96 h (+20%) as stroke volume was maintained at normoxic levels and heart rate increased (+36%). Pulmonary artery pressure increased (+35%) along with plasma catecholamine levels (+116-196%). There were sustained elevations of cerebral flow (radiolabelled microspheres) from 79.1 (+/- 9.2 SEM) to 121.6 ml X min-1 X 100 g-1 (+/- 10.8), coronary flow from 183 (+/- 22.1) to 373 ml X min-1 X 100 g-1 (+/- 46.3), diaphragm flow (+400%) and intercostal muscle flow (+186%) with no apparent redistribution of Qco. Therefore, the cardiac and peripheral circulatory response patterns are altered significantly in eucapnic hypoxia. The rate of O2 delivery to brain and several abdominal viscera is higher.

Animals↗
PubMed1985

Non-vagal reflex effects on medullary inspiratory neurons during inspiratory loading.

Studies were conducted to compare the first-breath responses of medullary Dorsal and Ventral Respiratory Group inspiratory (I) neurons to the mechanical loading (tracheal occlusion, TO) of inspiration in unanesthetized (decerebrate) and anesthetized (Dial) vagotomized cats, and to determine the sources of the sensory activity causing the changes in I-neuron activity. In decerebrate cats, TO resulted in a prolongation of the firing duration in 49% of the I-neurons. There was a delayed onset of firing in 7% of the I-neurons. The responses of I-neurons to TO in anesthetized cats were similar to the responses in decerebrate cats. Changes in I-neuron activity with TO were still present in cats with their cervical (C3-7) or thoracic (T1-9) dorsal roots cut, and absent when both cervical and thoracic dorsal roots were cut. The most probable sources of the cervical and thoracic afferent information altering medullary I-neuron activity during loading are the diaphragm and inspiratory intercostal muscles.

Anesthesia↗
PubMed1986

Effect of body temperature on the ventilatory responses in the lizard Gallotia galloti.

A new technique for recording ventilatory frequency on small lizards is described. This is based on the record of the electrical potential difference that spontaneously arises during the ventilatory cycle between an active stainless steel needle electrode, implanted on the membrane of the nasal cavity, and a reference stainless steel screw electrode implanted on the parietal bone. The nasal ventilatory signal coming from these electrodes, together with a simultaneous record of the electromyogram of intercostal muscles, was used to investigate the pulmonary ventilation of the lizard Gallotia galloti over the body temperature range 5-35 degrees C. The results suggest that the ventilation pattern of this lizard begins with a passive expiration, in which electromyographic activity is not present, followed by an active expiration and then an active inspiration, these being separated by a shorter muscular resting period. The active expiration lasts longer than the active inspiration over all the range of body temperatures studied. The ventilatory frequency increases exponentially with body temperature. The duration of the muscular activity during the ventilatory cycle, in the 10-35 degrees C range of body temperature, is approximately half the ventilatory period and decreases exponentially with body temperature at half the rate at which the ventilatory period decreases. The duration of several electromyographic events recorded during the ventilatory cycle also decreases exponentially with body temperature.

Animals↗
PubMed1992

High-frequency diaphragmatic flutter: symptoms and treatment by carbamazepine.

Classic diaphragmatic flutter, a rare disorder associated with dyspnoea, thoracic or abdominal wall pain, and epigastric pulsations, is caused by involuntary contractions of the diaphragm with a frequency of 0.5-8.0 Hz. We have seen three patients with diaphragmatic flutter of higher frequency not associated with respiratory disease. The patients presented with longstanding oesophageal belching, hiccups, and retching, respectively. The diagnosis was established by the presence on electromyography of the diaphragm and scalene and parasternal intercostal muscles of repetitive discharges of 9-15 Hz. Spirographic tracings, especially those of volume or flow vs time, showed similar high-frequency oscillations superimposed on tidal respiratory movements. Treatment with carbamazepine 200-400 mg three times daily led to disappearance or great improvement of flutter and clinical symptoms in all three patients. The phenomenon was not seen in other patients with chronic hiccups or oesophageal belching or in patients without these symptoms who had undergone electromyography or spirography for other reasons. Thus, high-frequency diaphragmatic flutter seems to be a new disease entity. The response to carbamazepine, which suggests that the flutter causes the symptoms, requires further study.

Adult↗
PubMed1984

Pressor effect of CO2 in the rat: different thresholds of the central cardiovascular and respiratory responses to CO2.

Rats were anesthetized with urethane and the vagi, aortic and carotid sinus nerves were sectioned bilaterally. Hypocapnia was induced by artificial hyperventilation with 100% O2. Administration of 5% CO2 in O2, without alteration of the respiratory rate or tidal volume, induced significant increases in mean systemic arterial pressure ( mSAP ) in rats with intact central nervous system (CNS) and after midcollicular section (36 +/- 4 and 34 +/- 2 mm Hg, respectively; mean +/- S.E.). Smaller but significant increases in mSAP (17 +/- 3 mm Hg) were induced by inhalation of 5% CO2 after section of the spinal cord at the C4 level. Ganglionic blockade with hexamethonium completely abolished the pressor response to CO2. In hypocapnic (paCO2 15.5 +/- 0.7 mm Hg) apneic rats with intact CNS, after denervation of the peripheral chemoreceptors, inhalation of 1.5% CO2 in O2 increased paCO2 to 22.3 +/- 1.2 mm Hg and mSAP by 16 +/- 1 mm Hg, but the animals remained apneic for up to 45 min of continuous CO2 administration. Higher FICO2s induced further immediate increases in mSAP and, after delays of up to 6-7 min, also a resumption of central rhythmic respiratory activity (monitored by the intercostal muscles or phrenic nerve electrogram). The paCO2 threshold for this respiratory response was 25 +/- 1 mm Hg. When rhythmic respiratory activity resumed, a further slight increase in mSAP and the appearance of respiratory modulated oscillations of the SAP were observed in most animals. When, after a period of CO2 inhalation, 100% O2 was again administered to the animals mSAP fell immediately, reaching the control level within 20-30 s, while the respiratory activity, if present, disappeared only after 1.5-2 min. From these experiments we conclude that in the hypocapnic rat, after denervation of the peripheral chemoreceptors: (1) CO2 induces a neurogenic hypertensive response even in the absence of rhythmic respiratory activity; (2) the central chemosensitive sites appear to be located in the ponto-medullary region and in the spinal cord; and (3) the central mechanisms responsible for the pressor response have a lower CO2 threshold and a much shorter latency than those responsible for the initiation of the rhythmic respiratory activity.

Animals↗
PubMed1990

The developmental expression of the cholinergic-specific antigen Chol-1 in the central and peripheral nervous system of the rat.

Antisera raised by the injection into sheep of presynaptic plasma membranes isolated from the purely cholinergic electromotor nerve terminals of Torpedo marmorata recognize a cholinergic-specific epitope, designated Chol-1 which has been shown to be gangliosidic in nature both in Torpedo (Richardson et al., 1982) and guinea-pig brain (Ferretti and Borroni, 1986). In rat brain the serum recognizes a group of antigenically-related minor gangliosides (Chol-1 alpha, beta and gamma) which migrate just below the standard gangliosides GQ, GT1B and between GD1b and GD1a, respectively. We have studied the developmental expression of these gangliosides in rat brain and hippocampus and in the neuromuscular junction of rat intercostal muscle in an attempt to correlate their expression with specific events in the development of the cholinergic neuron. The period in which Chol-1 is first detected suggests that it is expressed relatively late during the maturation process of the cholinergic synapse. This is supported by the finding: (a) that it is not detected in the growth cones (immature nerve terminals) in 5-day-old rat brain but is in the whole brain implying that only the more mature nerve terminals present at this stage express Chol-1; and (b) that Chol-1 is first expressed in the neuromuscular junction at a time in which functional synapses are already present. These results argue against a role for the Chol-1 antigens as recognition molecules in the formation of cholinergic synapses. The expression of Chol-1 in both the hippocampus and the neuromuscular junction correlates well with the establishment of the adult pattern of innervation; thus the Chol-1 antigens may be seen as markers for mature cholinergic terminals.

Aging↗
PubMed1993

Cloning and sequence analysis of a full length cDNA encoding human mitochondrial 3-oxoacyl-CoA thiolase.

The cDNA sequence of human mitochondrial 3-oxoacyl-CoA thiolase was determined. The nucleotide sequence contains an open reading frame of 1191 base pairs and encodes an amino acid sequence of 397 residues which exhibits 86.6% homology with that of the rat enzyme. Northern blot analysis gave a single mRNA species of 1.6 kb in the human liver, fibroblasts and intercostal muscle.

Acetyl-CoA C-Acyltransferase↗
PubMed1995

The mechanics of torso flexion: situps and standing dynamic flexion manoeuvres.

The mechanics of torso flexion has not been thoroughly investigated due to the lack of knowledge of tissue force-time histories during the performance of torso flexion exercises. An anatomically detailed, three-dimensional model that was sensitive to lumbar curvature and muscle activation patterns was used to assess tissue load distribution during the performance of both isometric and dynamic situps and standing flexion manoeuvres in 12 young men. Situps were performed starting with a flexed torso which was lowered to horizontal and then raised again (instrumentation restrictions did not allow subjects to rest their torsos when in the lowered position). Specific variables measured were air flow during inhalation-exhalation, intra-abdominal pressure, myoelectric activity of the torso muscles, intercostals, and rectus femoris, three-dimensional dynamic curvature of the lumbar spine and body segment displacements. Lumbar compressive loads greater than 3000 N were predicted for both straight leg and bent knee situps. No biologically significant differences were found between bent knee and straight leg situp techniques. RELEVANCE: The safety of situps as both a therapeutic modality and training exercise has been questioned for years but evaluation has suffered from a lack of knowledge of tissue loading. The load predictions in this study suggest that performing situps (both dynamic and quasi-static) imposes high levels of compressive loading (> 3000 N) on the low back. The issue of using straight legs or bent knees is probably not as important as the issue of whether or not to prescribe situps at all.

Journal Article↗
PubMed1988

Bloat in sheep (Ovis aries).

1. Most of the field studies on bloat are conducted with cattle and most of the laboratory experiments seeking to explain the various parameters associated with bloat are done with sheep. 2. Based on grazing behaviour, it would be expected that sheep might bloat more severely than cattle because they selectively choose to eat leaves over stems and chew what they ingest more frequently than cattle. Furthermore, sheep appear to select legumes over grasses because the legumes can be eaten more rapidly. However, because they are selective, sheep eat more slowly than cattle. Despite a higher bloat expectation, bloating in sheep is reported to be less of a problem than in cattle. 3. Although frothing of rumen ingesta was described earlier in cattle as the cause of acute legume bloat, experiments with frothy bloat in sheep preceded those in cattle. 4. Anti-frothing agents were used in sheep before cattle to treat acute legume bloat. 5. Experiments devoted to the study of eructation in ruminants were carried out on sheep, then cattle. 6. Convincing evidence that rumen motility does not cease during acute legume bloat was gathered using sheep. 7. Although the transected tracheal technique for the determination of the volume of eructated gas was developed with cattle, the pathway of eructated gas was confirmed with sheep. 8. All the current evidence accumulated from experiments with sheep supports the hypothesis that death due to legume bloat is caused by acute neural, respiratory, and cardiovascular insult resulting from the effect of the distended rumen on thoracic viscera, diaphragm, intercostal muscles, and the abdominal vena cava. 9. Experiments with sheep and cattle being fed scabrous and nonscabrous diets similar in chemical composition show that sheep are more resistant than cattle to the increase in intrarumen pressure, decline in rumen contraction amplitude, and decrease in rumen contraction frequency caused by nonscabrous diets. 10. The sequence of events in the reticulorumen during primary and secondary contractions previously described following visual and palpation experiments with cattle was confirmed by the use of myoelectrodes implanted in the various sacs of the reticulorumen of sheep. 11. Elevated intrarumen pressure is associated with an increase in the frequency of primary (mixing) and secondary (eructation) contractions (more secondaries than primaries).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Primary mediastinal endodermal sinus tumors: CT evaluation.

Five patients with primary mediastinal endodermal sinus tumor have been evaluated by computed tomography (CT). The tumors were all located in the anterior mediastinum. Prechemotherapy CT demonstrated large, irregularly enhancing inhomogeneous masses without fat components. Calcification was visualized in two tumors. Some parts of the pleura-lung interface were irregular in four cases. Obliteration of fat planes to pericardium and chest wall was evident in all cases, and there was infiltration of intercostal muscles in four. Postchemotherapy CT in two patients who responded to chemotherapy showed either newly developed cystic lesions or cystic change of the original mediastinal mass. The cystic masses had more regular borders, a homogeneous hypodense center, and a smooth peripheral rim of contrast-enhancing tissue.

Adolescent↗
PubMed1989

Surgical treatment of lung carcinoma involving the chest wall.

From 1969 to 1986, 97 patients with chest wall invasion by lung carcinoma (excluding superior sulcus tumours) underwent surgical resection in two hospitals, La Paz (Madrid) and La Fé (Valencia). The same surgical policy was used in both thoracic surgical units: extrapleural pulmonary resection when tumour involved only the parietal pleura (N = 36), and en bloc chest wall resection when the carcinoma extended into the ribs and intercostal muscles (N = 61). The tumour histology was classified according the WHO criteria. Lobectomy or bilobectomy was carried out in 72%, pneumonectomy in 18% and segmentectomy or wedge resection in 10% of the patients. The perioperative mortality was higher in the en bloc resection group 9/61 (15%) versus 2/36 (6%) for extrapleural dissection. The node staging was NO in 58/97 (60%), N1 in 16/97 (16%) and N2 in 23/97 (24%). The probability of survival was calculated by the Kaplan-Meier method collecting data from the perioperative survivors only. The overall 5-year survival was 23% with no significant differences between the en bloc resection and the extrapleural lung resection groups. The most important predictor of survival was the node stage. The 5-year survival for N1 and N2 were 8% and 6%, respectively. These percentages increased to 34% when N0 patients were considered. Other predictors of survival were not significant. The authors conclude that either extrapleural or en bloc chest wall resection are both valid procedures which may be used depending on the depth of local invasion.

Adenocarcinoma↗
PubMed1989

Spontaneous intercostal pulmonary hernia with subsegmental incarceration.

A case of acute intercostal pulmonary herniation due to vigorous coughing secondary to chronic bronchitis is reported in a 70-year-old male. Protruding pleura-covered lung tissue was found bulging through an intercostal space defect between the left midaxillary line and the infrasternal costochondral arch. A hernial sac consisting of parietal pleura and atrophic intercostal muscle confined a "sliding pouch" for two pulmonary segments of which one presented a demarcation zone of temporary incarceration interpreted as an entrapment of lung tissue between two ribs. A fracture gap was discovered affecting the anterior synostosis between ribs 7 and 8. Treatment was accomplished by anterior fixation of the ribs and by the basic principles of hernia repair between adjacent ribs. A case report and a brief survey of aetiological and anatomical classification is presented.

Aged↗