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Biomedical subjects

H Yamabayashi

Publications and source records attributed to H Yamabayashi.

At least 19 recordsLinked to original sources
PubMed1992

In vivo recording of electrical activity of canine tracheal smooth muscle.

Electrical activity of the tracheal smooth muscle was studied using extracellular bipolar electrodes in 37 decerebrate, paralyzed, and mechanically ventilated dogs. A spontaneous oscillatory potential that consisted of a slow sinusoidal wave of 0.57 +/- 0.13 (SD) Hz mean frequency but lacked a fast spike component was recorded from 15 dogs. Lung collapse accomplished by bilateral pneumothoraxes evoked or augmented the slow potentials that were associated with an increase in tracheal muscle contraction in 26 dogs. This suggests that the inputs from the airway mechanoreceptors reflexly activate the tracheal smooth muscle cells. Bilateral vagal transection abolished both the spontaneous and the reflexly evoked slow waves and provided relaxation of the tracheal smooth muscle. Electrical stimulation of the distal nerve with a train pulse (0.5 ms, 1-30 Hz) evoked slow-wave oscillatory potentials accompanied by a contraction of the tracheal smooth muscle in all the experimental animals. Our observations in this in vivo study confirm that the electrical activity of tracheal smooth muscle consists of slow oscillatory potentials and that tracheal contraction is at least partly coupled to the slow-wave activity of the smooth muscle.

Action Potentials↗
PubMed1992

31P-NMR study of skeletal muscle metabolism in patients with chronic respiratory impairment.

To evaluate the energy metabolism of peripheral skeletal muscle during exercise in patients with chronic respiratory impairment, the 31P-nuclear magnetic resonance (NMR) spectra of forearm muscle were investigated in nine patients and nine age-matched control subjects. We calculated the phosphocreatine (PCr) to PCr + inorganic phosphate (PI) ratio, the time constant of PCr recovery and the intracellular pH. The exercise consisted of repetitive hand grips against a 2-kg load every 3 s for 6 min (0.33 W). The patients showed a marked decrease in the PCr/(PCr + PI) ratio and pH in the muscle during exercise in contrast to the control subjects whose PCr/(PCr + PI) showed a minor decrease without any change in pH. The relationship between PCr utilization and pH demonstrated that anaerobic glycolysis switched on earlier in patients with chronic respiratory impairment. A split PI peak was observed in five of nine patients during exercise. The PCr/(PCr + PI) ratio during the last minute of exercise correlated significantly with the vital capacity (% predicted), with the FEV1/FVC, with the body weight, with the maximum strength of hand grip, and with the muscle mass. The results indicate impaired oxidative phosphorylation and the early activation of anaerobic glycolysis in the muscles of patients with chronic respiratory impairment. Several factors related to chronic respiratory impairment, such as disuse, malnutrition and dysoxia, would contribute to the metabolic changes observed in the muscles examined.

Aged↗
PubMed1992

Reperfusion after a two-hour period of pulmonary artery occlusion causes pulmonary necrosis.

The role of reperfusion injury in the progression to necrosis in pulmonary embolism was evaluated. To simulate this condition, we used a technique that enables occlusion and reopening of the pulmonary arterial branch supplying the right upper lobe in conscious rats. The rats were divided into five groups: the occlusion group (n = 12), in which the pulmonary artery (PA) branch was occluded without reperfusion; the reperfusion group (n = 12), in which the PA branch was reopened after a 2-h period of occlusion; and the reperfusion-SOD (n = 9), reperfusion-IM (n = 8), or reperfusion-IA-SOD (n = 6) groups, in which superoxide dismutase (SOD), indomethacin (IM), or inactivated SOD (IA-SOD), respectively, was administered during reperfusion. The lungs were removed 24 h after the PA occlusion, and histologic examination was performed. In the occlusion group, the alveolar structure of the right upper lobe was well preserved, and there was no erythrocyte or leukocyte accumulation. The only significant changes compared with the control lobe was the appearance of wavy internal elastic lamina of the PA and slight neutrophil adherence to the endothelial cells. In contrast, the right upper lobe of the reperfusion group disclosed numerous foci of hemorrhagic necrosis, with disrupted alveoli and leukocyte accumulation in all cases. With SOD treatment, the changes compatible with hemorrhagic necrosis were attenuated to the level of the control lobes. However, neither IM nor IA-SOD decreased these changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Expiratory activity of the inspiratory muscles during cough.

To investigate the neural mechanism of the expiratory activity of the inspiratory muscles during a cough, EMG of the respiratory muscles were recorded in anesthetized and tracheostomized dogs. A laparoscope was used to minimize injury to the abdominal muscles for implantation of the electrodes into the costal diaphragm. During the expulsive phase of a cough, the diaphragm was active in 7 of 12 dogs and the external intercostal muscle was active in 3 of 6 dogs. During a cough, the expiratory activity of the diaphragm, after the termination of its inspiratory activity, started at 52.9 +/- 24.6 ms, and that of external intercostal muscle started at 51.1 +/- 20.5 ms. The expiratory activity of the internal intercostal muscle and of the transversus abdominis started at 34.3 +/- 13.0 and 27.8 +/- 15.2 ms, respectively. The onset of expiratory activity of the inspiratory muscles is significantly later than that of expiratory muscles. Continuous activity in the expiratory muscles evoked by airway occlusion, i.e., Hering-Breuer reflex, was suppressed during the inspiratory phase of a cough, but not suppressed during the expulsive phase even when the expiratory activity of the diaphragm was observed. We concluded that the expiratory activity of inspiratory muscles is controlled independently of both expiratory activity of the expiratory muscles and inspiratory activity of the inspiratory muscles.

Animals↗
PubMed1992

[A case of mediastinal teratoma--differentiation from lung abscess and bronchogenic carcinoma].

A 38-year-old man was admitted with persistent productive cough and right anterior chest pain. Chest X-ray showed two large masses connected with each other, one in the right lung field and the other in the anterior mediastinum. A tentative diagnosis of either lung abscess or bronchogenic carcinoma was initially made, because of elevated serum tumor markers (SLX and SCC) and persisting refractory inflammatory sings. However, open chest drainage revealed a few fine hairs and atheromatous materials within the masses, and the diagnosis of teratoma was made. We removed these masses, and investigated the reason for the elevation of tumor markers. Staining with SLX monoclonal antibody demonstrated that the pancreatic tissue in the masses contained SLX. Although this is the first reported case of teratoma producing tumor marker (SLX), it is highly possible that tumor markers may be elevated in the majority of patients with teratoma because of the genesis of this tumor.

Adult↗
PubMed1992

[Activity of the respiratory muscles during natural defecation: a study on experimental animals].

Activity of the respiratory muscles during natural defecation was studied in two anesthetized and two decerebrate dogs. In anesthetized dogs, excitation of the abdominal muscles and an increase in gastric pressure were observed during defecation. However, pleural pressure was little influenced by such increase in abdominal pressure, maintaining the same rhythmic changes as observed during spontaneous respiration. The rhythmic changes in pleural pressure were associated with rhythmic activity of the diaphragm. When gastric pressure increased during defecation, the diaphragmatic activity also increased during both the inspiratory and expiratory phases. In a decerebrate dog, airflow and airway pressure changed similarly to during defecation. The diaphragm was continuously active, with superimposed rhythmic augmentation. In a paralyzed and artificially ventilated dog with open-chest, the phrenic nerve similarly developed discharges. We conclude that the non-respiratory activity and rhythmic augmentation of phrenic nerve discharge during defecation is pre-programmed in the command for defecation. The activity of phrenic motoneurons may be further modulated by changes in thoracic and abdominal pressure. These mechanisms may act together to coordinate respiration and defecation.

Anesthesia↗
PubMed1991

Influence of central respiratory activity on the cough response in anesthetized dogs.

Cough responses evoked by mechanical stimulation of the tracheobronchial mucosa in anesthetized and tracheostomized dogs were studied. The most common response was a group of coughs. Phase relationships between coughing and spontaneous respiration during the cough initiation and resolution periods were categorized as either synchronized or unsynchronized. We defined the synchronization as the coincidence of an expiratory thrust and the early-expiratory phase of respiration. During the cough initiation period, the incidence of synchronization increased as central respiratory activity was enhanced by hypercapnia or as the cough center's activity was suppressed by deep anesthesia. Synchronization decreased as central expiratory activity was enhanced by expiratory threshold loading. During the cough resolution period, synchronization occurred in conjunction with a gradual decrease in the cough center's activity. Coughing could be evoked when the dog was made apneic either by hyperventilation or by the Hering-Breuer reflex. In either case, apnea persisted after coughing subsided. These findings suggest that mechanical stimulation directly activates the cough center rather than the respiratory center; and that synchronization is determined by the relative strengths of the respiratory and cough center's activities.

Afferent Pathways↗
PubMed1990

A 1-year time course study of the relaxation times and histology for irradiated rat lungs.

To investigate the NMR relaxation times for irradiated rat lung tissue, we measured T1 and T2 at 11 different times during the injury's 1-year time course. A biexponential analysis of T2 was used to determine T2 fast (T2f) and T2 slow (T2s). In addition, we measured water content and correlated changes in the relaxation times with pathological changes. The correlation indicates the following: (1) Shortly after irradiation, the biexponential T2 decay for 1/3 of the samples became monoexponential and there were no noticeable pathological changes observed using light microscopy. (2) During radiation pneumonitis, T2f and T2s were prolonged. This accompanied acute edematous changes and inflammatory cell infiltration. (3) Finally, during radiation fibrosis T1 shortened and collagen increased. We observed no significant correlation between relaxation time changes and water content changes throughout the 1-year time course.

Animals↗
PubMed1990

T2 of endotoxin lung injury with and without methylprednisolone treatment.

NMR relaxation times (T1 and T2) and the water content (WC) of in vitro rat lungs were measured during the course of endotoxin lung injury in rats. Measurements of normal lungs, untreated endotoxin-injured lungs, and endotoxin-injured lungs treated with methylprednisolone (MPSL) were compared. The untreated endotoxin lungs showed prolongation of the fast and slow T2 components (T2f and T2s), but no significant changes in T1 or water content. Also, there was no correlation between 1/WC and relaxation rates or between T1 and T2. MPSL treatment prevented T2f and T2s prolongation; however, the duration of MPSL effectiveness was limited. Animals which were treated with MPSL more than 7 h prior to measurements showed T2 prolongation. This study indicates that NMR relaxation times, particularly T2, can be useful in evaluating lung injuries and their treatments.

Animals↗
PubMed1990

Acute respiratory failure in multiple sclerosis.

A 23-year-old woman developed acute respiratory failure in the course of multiple sclerosis. The lack of bulbar dysfunction, the presence of quadriplegia, and the bilateral diaphragmatic weakness indicated the presence of spinal cord lesions involving pyramidal tracts bilaterally. Magnetic resonance imaging revealed a cervical demyelinating lesion between C1 and C3.

Acute Disease↗
PubMed1990

Transient neuromuscular impairment resulting from prolonged inhalation of halothane and enflurane.

Inhalation anesthesia first with halothane followed by enflurane relieved a patient with status asthmaticus who was refractory to conventional therapy including mechanical ventilation. After 13 days of anesthesia while on mechanical ventilation and employing nondepolarizing muscle relaxants, significant neuromuscular impairment, manifested by tetraplegia and sensory disturbance, developed. Anesthesia was discontinued on day 14, and the patient was weaned from mechanical ventilation on day 16. Over the next two months, the neuromuscular impairment markedly improved. Halothane was associated with cardiac arrhythmias and hepatitis necessitating replacement by enflurane. Enflurane appeared to be as effective a treatment for refractory asthma as halothane. The most probable cause of the neuromuscular impairment in our patient was the long-term use of inhalation anesthetics or nondepolarizing muscle relaxants.

Adult↗
PubMed1990

Continuous positive airway pressure breathing in supine and upright postures.

Continuous positive airway pressure (CPAP) breathing of 10 cmH2O was applied to 10 healthy conscious subjects both in supine and 70 degree head-up postures. CPAP increased the end-expiratory lung volume from 2.44 +/- 0.66 (S.D.) to 3.07 +/- 0.68 liters in supine subjects, and from 3.01 +/- 0.57 to 3.64 +/- 0.57 liters in head-up subjects. During CPAP, rib cage motion became predominant when compared to abdominal motion in upright posture. Among the respiratory parameters, inspiratory duration was significantly shortened during CPAP in either posture, but was changed less significantly by individual posture change alone. Mean inspiratory flow decreased during CPAP only in upright posture. Abdominal muscles were recruited for expiration during CPAP in either posture, and the EMG recorded from the lower intercostal space developed inspiratory activity during CPAP in head-up posture. All of 10 subjects felt most dyspneic during CPAP with the head-up. We conclude that the mechanism of increase in lung volume during CPAP is mediated by different pathway from that of posture change, and that CPAP in upright posture can alter the respiratory pattern of the subject.

Adult↗
PubMed1990

[Control mechanism of the respiratory muscle during forced expiration].

Control mechanism of the respiratory muscle during forced expiration was analyzed. Respiratory flow. EMG of the intercostal muscle (IC), external oblique (EO) and internal oblique (IO) abdominal muscle were analyzed in eleven healthy volunteers. The pattern of EMG activity during forced expiration could be classified according to its shape i.e., taper- or hill-shaped. The taper shape was found in 7 of 9 subjects for IC and in 8 of 11 subjects for EO. The hill shape was found in 4 of 6 subjects for 10. Twelve consecutive trials without intervals did not alter the pattern of flow-volume curve, activity of respiratory muscle and frequency component (i.e., H/L ratio). When the expiratory circuit was obstructed for a short interval during forced expiration, the rise in pleural pressure was slight but that in oral pressure was large, and the activity of respiratory muscle decreased for a short period. The latencies from the onset of expiratory circuit obstruction to the reduction in EMG activity were 61.5-100 msec. In IC, 61.5-106.5 msec in EO. and 58.0-92.3 msec in 10. These values did not differ significantly any given subject. Airway anesthesia with xylocaine did not alter latency. In conclusion, the pattern of respiratory muscle activity for forced expiration is predetermined and is specific for each muscle. Negative feedback from receptors in airway or in respiratory muscle was strongly suggested. Repetitive trials up to twenty times did not cause respiratory muscle fatigue.

Adult↗
PubMed1990

[A case report of diaphragmatic flutter].

A 18-year-old female complained of a dyspneic sensation and involuntary movements in the epigastrium. On physical examination, fine rhythmic movements in the epigastrium were observed on each inspiration with a rate of 5-10 per breath. Arterial blood gas analysis was normal. Recording of the respiratory parameters and the EMG of respiratory muscles were performed. Analysis of the respiratory flow revealed that her spontaneous inspirations consisted of short inspirations (i.e., flutter wave) (150-170 beats per minute). EMG of respiratory muscles demonstrated that these flutter waves were driven by intercostal muscles and diaphragm. The flutter waves were not suppressed by breath holding at the maximal inspiration. With intravenous injection of 200 mg of diphenylhydantoin, flutter waves disappeared within 10 minutes. There were no abnormal findings on chest roentgenogram, electrocardiogram, head CT scan and MRI of the cervical spine. During one year's follow up no attack developed again. We have encountered 3 cases of the syndrome since 1981. In two of them, the spontaneous respiration was superimposed on a high-frequency wave throughout the whole respiratory cycle while in one case the high-frequency wave developed only in the inspiratory phase of spontaneous respiration. In the present case the respiratory flow pattern was similar to the last mentioned and the EMG-analysis of respiratory muscles confirmed that the flutter waves were driven by intercostal muscles and diaphragm. Furthermore, synchronization of activities of the two respiratory muscles suggests that the syndrome is of central origin.

Adolescent↗
PubMed1989

Effect of cold pressor test on carbon monoxide diffusing capacity in normal subjects.

We investigated changes in the pulmonary carbon monoxide diffusing capacity (DLco) during the cold pressor test (CPT) on 25 normal subjects. In 10 of them we also observed changes in circulatory parameters by a computerized dual cadmium telluride detector system, using an equilibrium radionuclide blood-pool label. DLco and DLco per unit of alveolar volume (DLco/VA) averaged in the control period were 29.4 +/- 4.1 ml/min/mm Hg, 6.1 +/- 0.8 ml/min/mm Hg/l (mean +/- SD). During the 2nd minute of CPT, DLco increased by 3.6 +/- 1.5% and DLco/VA by 5.1 +/- 1.5% (mean +/- SE). The systemic blood pressure increased by 17% (mean increase) whereas the heart rate and the stroke volume remained unchanged. The increases were small but significant (p less than 0.05, p less than 0.01, respectively). We conclude that the increase in DLco is due to cold-induced systemic vasoconstriction followed by a passive shift of blood into the pulmonary vasculature.

Adult↗
PubMed1989

Role of the mediastinum as a part of the chest wall: analyzed by computed tomography.

Using computed tomography (CT), geometrical changes in pulmonary structures in 4 human volunteers were analyzed. A series of parallel transaxial CT scans of the lung were obtained for each volunteer while he held his breath at maximal inspiration and maximal expiration. Changes in pulmonary structures were evaluated by comparing the maximal inspiration scans for each slice position. The longitudinal displacement of the lung volume was categorized as either a rib cage displacement or a diaphragm-abdominal displacement. The ratio of diaphragm-abdominal contribution to vital capacity was 0.49-0.65 for the volunteers. The thoracic volume displacement was categorized as either a mediastinal displacement or a rib cage displacement. The former was considerably larger than the latter. Since the rostral end of the mediastinum is fixed to the thoracic cage and the caudal end is fixed to the diaphragm, we conclude that the mediastinum-diaphragm boundary converts the axial force generated by the diaphragmatic excursion into radial force.

Adult↗
PubMed1989

Dual-respiratory rhythms. A key to diagnosis of diaphragmatic flutter in patients with HVS.

We discuss three cases of diaphragmatic flutter in patients with extreme polypnea and symptoms of respiratory alkalosis. Initially, the diagnosis for each case was HVS. However, analysis of the respiratory pattern during attacks revealed two frequencies. A fast respiratory rhythm (230 to 250 breaths per minute) was superimposed on a slow rhythm (15 to 30 breaths per minute). The fast rhythm maintained blood gases at normal limits or hypocapnic levels. The dual respiratory rhythms, which do not occur with HVS, indicated diaphragmatic flutter. In addition, the usual treatment for HVS-breathing CO2 mixed air-did not influence the attacks. For two of the three patients, an intravenous dose of DPH suppressed the abnormal respiratory patterns immediately and completely. The third patient responded to an intramuscular injection of haloperidol. For these cases, the dual respiratory rhythms were the key to diagnosis of diaphragmatic flutter which accompanied hyperventilation.

Adolescent↗