Effect of salbutamol on respiratory muscle function and ventilation in awake canines

The effect of the beta-agonist bronchodilator salbutamol on respiratory muscles and ventilation is uncertain. The presence of beta2 receptors on skeletal muscles and increased diaphragm contractility in vitro with salbutamol predict a significant effect that has not been confirmed, in vivo in non-fatigued diaphragm or in clinical studies using standard bronchodilator dosages. Therefore, we infused salbutamol at a higher dosage (23.3 microg/min) used clinically for treatment of respiratory emergencies, while measuring directly the length, shortening and EMG activation of costal and crural diaphragm, parasternal intercostal and transversus abdominis muscles, in 10 awake canines. At this salbutamol dosage, ventilation and tidal volume increased significantly during both resting and CO2-stimulated breathing. Salbutamol elicited significant increases in respiratory muscle shortening with much smaller increases in EMG activity, so the proportionally greater muscle shortening per unit EMG showed increased muscle contractility. The effects of salbutamol were not extinguished by inspiratory flow resistance or fluid challenge but were reversed specifically by the beta-blocker, propranolol. This study demonstrates that, in sufficient intravenous dosage, the beta-agonist salbutamol elicits increased ventilation and a beta2 receptor-mediated increase in contractility of respiratory muscles.

Reversible dimerization of 20 kilodalton human growth hormone (hGH)

A noncovalent dimer of the 22 kilodalton human growth hormone (22 K-hGH) is known to have diminished somatogenic activity compared with monomeric 22 K-hGH. In the present study, we examined the biological activity and physicochemical behaviour of a noncovalent dimer of the 20 kilodalton human growth hormone (20 K-hGH), an isoform of 22 K-hGH. Analysis of the equilibrium between monomeric and associated forms revealed that the associated 20 K-hGH was present in the dimeric form in aqueous solution. The kinetics of dimerization in rat plasma followed the theory of dissociation-association equilibrium, and more than 99% of 20 K-hGH molecules existed as a monomer in the equilibrium state at the physiological hGH concentration. Analysis of the pharmacokinetics showed that the ratio of the administrated dimer in rat circulation decreased from 43% to less than 4% in 2 h. A preparation of noncovalent dimeric 20 K-hGH had essentially the same degree of biological potency as that of a monomer in both in vitro and in vivo bioassays. In conclusion, dimerization of 20 K-hGH is reversible both in vitro and in vivo and a noncovalent dimer can function as a pharmaceutically active component of a 20 K-hGH preparation, in contrast to a 22 K-hGH preparation.

Secretion of authentic 20-kDa human growth hormone (20K hGH) in Escherichia coli and properties of the purified product

Using Bacillus amyloliquefaciens neutral protease gene (npr), we have constructed a secretion system of 20-kDA human growth hormone (20K hGH) in E. coli. The secretion-signal region from npr was modified inserting a fragment coding a 2Lys-5Leu cluster. In this system we found that co-expression of glutathione reductase remarkably increased accumulation level of 20K hGH in periplasm and confirmed that secreted 20K hGH was correctly processed. The recombinant 20K hGH was highly purified and subjected to analyses of physicochemical properties and biological activities which are still unclear and controversial due to difficulty in preparing the sample with authentic structure. The secreted recombinant product had authentic disulfide linkages and showed molecular weight of 20,270.5 +/- 3.7 (theoretical value, 20,269.9). The results suggest that the recombinant 20K hGH is a full agonist on rat growth promotion and lipolysis stimulation in isolated rat adipose tissues. In particular, the lipolysis-stimulating activity of 20K hGH was distinct as compared with that of 22K hGH under physiological concentration. Cell proliferation activity via prolactin-receptor in Nb-2 lymphoma was obviously low as compared with that of 22K hGH.

Differential respiratory activity of four abdominal muscles in humans

Together the abdominal muscles contribute significantly to ventilation under some conditions, but there is little information regarding individual recruitment and timing of activation of the four abdominal muscles in humans. Fine-wire electrodes were inserted under direct vision guided by high-resolution ultra-sound into the rectus abdominis (Rectus), external oblique (Extern), internal oblique (Intern), and transversus abdominis (Transv) in nine awake healthy subjects. Airflow, end-tidal CO2, and moving-average EMG signals were recorded during 1) supine resting and CO2-stimulated ventilation and 2) resting ventilation in the standing position. During resting supine breathing, Transv showed significant phasic EMG activity during expiration. As posture changed from supine to standing, phasic activity during resting ventilation was greatest in Transv, with lesser activity in Intern and Extern, while Rectus remained inactive. As CO2 began to increase, Transv was activated first, followed by Intern, the Extern, and finally Rectus. With moderate CO2 stimulation, Transv and Intern were more active than was Extern and Rectus remained least active. EMG activities in the expiratory muscles after cessation of expiratory flow (postexpiratory expiratory activity) and in expiratory muscle activity preceding expiratory flow were observed consistently during supine stimulated ventilation and standing resting ventilation. These activities before and after expiratory airflow were prominent with stimulated ventilation during a substantial portion of inspiration, suggesting dual control of inspiratory pump action by both inspiratory and expiratory muscles, which provide acceleration and braking actions, respectively. These results suggest that in awake humans 1) during resting ventilation, expiration is an active process; 2) abdominal muscles are activated differentially; 3) Transv is the most active, Intern and Extern are intermediate, and Rectus is the least active expiratory muscle; and 4) during stimulated ventilation, inspiratory and expiratory muscles contribute dually to inspiratory pump action.

[Effect of nasal CPAP on human diaphragm position and lung volume]

The cephalic margin of the zone of apposition (ZOA) was observed with ultrasonography at ambient pressure and during nasal continuous positive airway pressure (nasal CPAP) in nine awake healthy males in a supine position. In a relaxed state at ambient pressure, there was a significant (p < 0.001) linear relationship between lung volume and the movement of the cephalic margin of the ZOA over the range from maximum expiratory position (MEP) to maximum inspiratory position (MIP). With nasal CPAP, functional residual capacity increased significantly (p < 0.01) in proportion to the increase in CPAP. At 20 cmH2O CPAP, the mean increase in volume at end expiration was 36% of the vital capacity measured at ambient pressure. The cephalic margin of the ZOA moved significantly (p < 0.01) in a caudal direction as CPAP was increased. At 20 cmH2O CPAP, the cephalic margin of the ZOA at end expiratory position (EEP) had moved 55% of the difference from MIP to MEP measured at ambient pressure. The end expiratory diaphragm position during nasal CPAP was lower than the diaphragm position at ambient pressure when lung volumes were equal. These results suggest that during nasal CPAP the chest wall is distorted from its relaxed configuration, with a decrease in rib cage expansion and an increase in outward displacement of the abdominal wall.

[Effect of nasal-CPAP and hypercapnia on human abdominal muscles]

The effect of nasal continuous positive airway pressure (nasal-CPAP) and hypercapnia on abdominal muscles was investigated in 10 healthy volunteers in the supine position. Pairs of fine wire electrodes were inserted into the rectus abdominis, external oblique, internal oblique and transversus abdominis under direct vision provided by high resolution ultrasound echography. Ultrasound provided clear visualization of the individual muscle layers and the guide needle for electrode insertion. Monitoring end tidal CO2 (ETCO2), 1) nasal-CPAP of 15 cmH2O was applied, 2) CO2 was then added to the inspiratory limb of the nasal-CPAP system, and 3) CO2 rebreathing was also performed without nasal-CPAP. Electromyograms (EMG) were sampled and integrated. Peak values of integrated EMG were measured under the following three conditions, normocapnia, 7% ETCO2, and 9% ETCO2, with and without nasal-CPAP. In each abdominal muscle, the percentage of patients with expiratory EMG activity increased with increasing ETCO2, regardless of nasal-CPAP. Among the four muscles, the transversus abdominis was recruited most frequently, the rectus abdominis least frequently. The EMG from each muscle was activated by nasal-CPAP of 15 cmH2O under each of the three conditions. We conclude that in humans 1) nasal-CPAP and hypercapnia synergistically activate abdominal muscles, 2) the transversus abdominis is the primary expiratory muscle, and 3) the rectus abdominis is an accessory expiratory muscle.

[A clinical study of fulminant Legionnaires' disease]

Seven cases of fulminant Legionnaires' disease treated at Kitasato University Hospital between 1985 and 1992 were reviewed. These patients were male with a mean age of 55.9 years (range, 37-67 yrs), and five were heavy alcohol drinkers. All seven patients required mechanical ventilation. Four patients recovered (group 1) and three expired due to respiratory failure (group 2). The mean interval from initial symptoms to the development of respiratory failure was 8.8 days in group 1 and 6.0 days in group 2, except in the one patient with lung cancer (case 6). The progression of pneumonia was more rapid in group 2. The mean intervals from admission to administration of erythromycin were 1.5 days and 3.5 days, respectively, in groups 1 and 2. In group 1, pulmonary infiltrates and respiratory insufficiency worsened for the first few days after erythromycin administration but improved thereafter. The average duration of ventilatory care in group 1 was 13.3 days. The administration of rifampicin combined with erythromycin may be useful for the treatment of fulminant Legionnaires' disease. When fulminant pneumonia is encountered in a middle-aged or elderly male alcoholic, Legionnaires' disease should be suspected and erythromycin administration with rifampicin should be initiated as early as possible.

[A case of sho-saiko-to-induced pneumonitis, diagnosed by lymphocyte stimulation test using bronchoalveolar lavage fluid]

A 66-year-old Japanese man was admitted to our hospital with fever, cough and dyspnea. He had been taking Sho-Saiko-to, a traditional Chinese medicine, for twenty days. On admission, chest X-ray examination revealed a reticular pattern in the bilateral lungs, and respiratory failure was evident. Serum levels of CRP and LDH were elevated. A differential cell count of the bronchoalveolar lavage fluid (BALF) showed that lymphocytes and eosinophils were increased. Alveolitis with lymphocyte and plasma cell infiltration was observed in a pathological specimen obtained by transbronchial lung biopsy. After all drugs had been discontinued, PaO2, serum CRP and serum LDH improved, and the reticular pattern in the bilateral lungs gradually resolved without administration of corticosteroids or antibiotics. A lymphocyte stimulation test for Sho-Saiko-to using BALF gave a positive result, although LST using blood gave a doubtful reaction. The diagnosis of Sho-Saiko-to-induced pneumonitis was made from the clinical course, laboratory findings, BALF cell analysis, pathological findings and LST using BALF. Only 13 cases of pneumonitis due to administration of traditional Chinese medical drugs have been reported. This case suggests that LST using BALF is useful for the diagnosis of drug-induced pneumonitis.

[Aniline-induced methemoglobinemia monitored by pulse oximetry]

A case of aniline-induced methemoglobinemia is reported. When the pulse oximeter reading (SpO2) was 80%, the oxygen saturation measured by a co-oximeter (SaO2) was 61.2%, the oxygen saturation calculated from PaO2 values was 98.9% and methemoglobin level was 38.8%. After methylene blue injection, methemoglobin level decreased gradually. With a decrease of methemoglobin level, SpO2 approached SaO2. If disparity between SpO2 and the oxygen saturation calculated from PaO2 values is noted, the presence of methemoglobinemia must be suspected. In clinical situations, the pulse oximeter permits the continuous noninvasive monitoring of oxygen saturation. It is necessary, however, to consider the potential errors in pulse oximetry.

Differential function of the costal and crural diaphragm during emesis in canines

In six mongrel dogs under thiopental anesthesia, piezoelectric transducers and bipolar electromyographic (EMG) wires were installed onto left costal, medial crural and lateral crural segments of the diaphragm. During CO2 rebreathing, shortening and EMG activity increased significantly in all three regions of the diaphragm compared to resting breathing. During emesis, (1) both shortening and EMG activity significantly increased compared to resting in costal segment; however, (2) lateral crural shortening was not increased in spite of significant increase in EMG activity; furthermore, (3) the medial crural segment lengthened without any increased EMG activity. These results demonstrate a differential recruitment of costal and crural diaphragm segments, and an additional differential activity within the crural segment between medial and lateral crural regions, during emesis. This activity of the canine diaphragm is consistent with a central influence of emesis upon individual regions of the diaphragm.

Lung cancer accompanied by erythema

Skin manifestations associated with malignant diseases are designated syndroma dermatotumorale. A case of lung cancer combined with atypical erythema is reported. A 70-year-old man was admitted to hospital because of a 4-month history of atypical erythema of unknown origin. A nodule in the right lung was revealed on chest roentgenogram which was diagnosed as lung cancer. After right upper lobectomy, the erythema regressed gradually and disappeared completely in 7 days. It is suggested that the erythema was a manifestation associated with the lung cancer.

Oxidation of linear terpenes and squalene variants by Arthrobacter sp

Cells of Arthrobacter sp. that had been isolated from soil were used to study oxidation of some linear terpenes and squalene variants. The cells oxidized geraniol, nerol, and farnesol to the corresponding aldehydes, with partial conversion of the geometrical isomerism of the alpha,beta-double bond. The squalene variant, squalene-2,3-oxide, was cleaved to 9,10-epoxygeranylacetone and geranylacetone. Squalene-2,3-22,23-dioxide was cleaved to 9,10-epoxygeranylacetone. These products were optically active, and their stereochemistry and optical purity were determined.