Control of ventilation in extreme-altitude climbers.

Ten climbers who participated in the Nepal-Japan Kangchenjunga Expedition (altitude, 8,478-8,586 m) in 1984 were examined for their hypercapnic and isocapnic hypoxic ventilatory responses (HCVR and HVR) at sea level before and after the expedition. Five climbers who reached an altitude higher than 8,000 m, [designated high-performance climbers (HPC)] exhibited significantly higher HVR than five climbers who did not [low-performance climbers (LPC)]. On the other hand, no significant difference in HCVR was seen between HPC and LPC. Our results were in agreement with the findings reported by Schoene et al. (J. Appl. Physiol. 56: 1478-1483, 1984) obtained in the American Medical Research Expedition to Everest in 1981. Significant depression in HVR in five climbers was found even 35-40 days after the expedition, which was accompanied by decreased arterial partial pressure of CO2 and increased pH at rest. Hence, the effect of altitude acclimatization in the climbers exposed to extreme altitude may have still persisted at the time of the postexpedition study. Our results confirmed that HRV evaluated at sea level may be used as an indicator of a climber's capability at great high altitude.

Difference in the effects of acetazolamide and ammonium chloride acidosis on ventilatory responses to CO2 and hypoxia in humans.

The effects of acetazolamide, a potent carbonic anhydrase inhibitor, and ammonium chloride (NH4Cl) on arterial blood gas tension, resting ventilation, and ventilatory responses to CO2 (HCVR) and hypoxia (HVR) were studied in healthy male subjects. Both drugs induced chronic metabolic acidosis with the reduction in plasma bicarbonate by a mean of 7.0 +/- 2.0 (S.D.) mM after acetazolamide and by 5.6 +/- 1.8 mM after NH4Cl. The ratio in the decrement of PaCO2 to that of plasma bicarbonate (delta PaCO2/delta [HCO3-]) was 1.51 in the former and 0.98 in the latter. Both drugs increased inspiratory minute ventilation (VI) predominantly due to increased tidal volume (VT) with acetazolamide and to increased respiratory frequency (f) with NH4Cl. In HCVR, the increments in CO2- ventilation slope and in ventilation at PETCO2 60 mmHg after drug administration were 0.77 +/- 0.51 l X min-1 X mmHg-1 and 20.0 +/- 11.2 l/min with acetazolamide and 0.59 +/- 0.40 l X min-1 X mmHg-1 and 8.0 +/- 2.8 l/min with NH4Cl, respectively. On the other hand, HVR both in terms of delta VI/delta SaO2 slope and of ventilation at SaO2 75% significantly increased after NH4Cl but not after acetazolamide administration. Thus, augmented VT and HCVR in the acetazolamide group and increased f and HVR in the NH4Cl group suggested that the central chemosensitive mechanism in the former and the peripheral chemosensitive mechanism in the latter may predominantly be responsible for the elevated ventilatory activities.

Effect of chlormadinone acetate, a synthetic progesterone, on hypoxic ventilatory response in men.

Ten healthy young males were studied with a double-blind, cross-over trial to determine whether or not chlormadinone acetate (CMA), a potent synthetic progesterone, augments hypoxic chemosensitivity. Seven days after CMA administration, inspiratory minute volume (VI) and tidal volume (VT) significantly increased. PaCO2 decreased by 3.0 +/- 2.6 (S.D.) Torr (p less than 0.05) and plasma bicarbonate decreased by 2.9 +/- 1.1 mM (p less than 0.01). During CMA administration, the atmospheric hypoxic ventilatory response (HVR), assessed by minute ventilatory (delta VI/delta SaO2), and occlusion pressure responses (delta P .2/delta SaO2), significantly increased about 1.9 (p less than 0.05) and 1.6 times (p less than 0.01) compared to the placebo response, respectively. The calculated normocapnic HVR (delta VI/delta SaO2) increased about 2.3 times the placebo run. Hypoxic response evaluated by the withdrawal test, which represents the peripheral chemosensitivity without involving the influence due to secondary hypoxic depression, was about 1.7 times the placebo response (p less than 0.05). We conclude that CMA augments hypoxic respiratory chemosensitivity.

Low-degree oxidized scleroglucan and its hydrogel.

A controlled oxidation of scleroglucan was performed with sodium periodate to prepare aldehyde derivatives (scleraldehyde) with a low degree of oxidation (10 and 20%), which were utilized for crosslinking reactions with hexamethylenediamine. The structural characterization of scleraldehydes and their corresponding hydrogels was attempted by small-angle X-ray scattering (SAXS). While scleraldehyde with a higher degree of oxidation (> or = 50%), according to an earlier research, was found to disentangle into single chains as the degree of oxidation increases; scleroglucan bearing a low percentage of aldehydic groups (up to 20%) retains mainly the conformation of the natural polysaccharide, thus the system can be represented as composed of triple helices with only minor disentanglements at the sites where the aldehyde groups are present. The hydrogel prepared from scleraldehyde with a low degree of oxidation is brittle and fragmented, in contrast to the elastic/homogeneous hydrogel earlier prepared from scleraldehyde with a high degree of oxidation. The hydrogel from scleraldehyde with a low degree of oxidation was found to possess a network structure that consisted mostly of the triple helices crosslinked in specific points where the triple helices are disentangled into single chains because of the presence of the aldehyde groups.

Quantitative determination of tocopherols by high-speed liquid chromatography.

A high-speed liquid chromatographic method for the determination of alpha-, beta-, gamma- and delta-tocopherols using a spectrophotometer or a spectrofluorometer, is described. The best results were obtained using a 2.3 mm i.d. x 500 mm normal phase partition column, JASCO-PACK WC-03-500 and a spectrofluorometer as a specific detector. A mixture of diisopropyl ether and n-hexane (2:98) was used as the mobile phase. A flow rate was set at 0.8 ml/min. A mixture of pure alpha-, beta-, gamma- and delta-tocopherols or natural tocopherols in vegetable oils were separately determined by this method.

Studies on the factors influencing the hydrogen peroxide hemolysis test.

There seems to be a greater variation between laboratories in hydrogen peroxide hemolysis techniques than in other clinical laboratory procedures. In this report, factors influencing hemolytic values were examined and the effect of the combination of these factors on the results was analysed statistically by using the orthogonal array. Factors influencing hemolysis induced by hydrogen peroxide were as follows; the concentration of hydrogen peroxide, temperature in the peroxide reagent when added to the red cell suspension, the red cell concentration in the cell suspension and the addition of charcoal to the reaction mixture. However, addition of charcoal may not be essential to stabilize the hemolytic values and other factors such as keeping blood for 4 hours at room temperature before testing, the difference between investigators, a reaction time 2 or 3 hours and the technique of adding peroxide reagent to the cell suspension, had little effect on hemolysis. The most important factor was the temperature in hydrogen peroxide solution. The estimated hemolytic values by the orthogonal array linearly correlated with the plasma tocopherol levels.

[Recent advances in imaging in diagnosis and treatment of tuberculosis].

Recent advances in imaging have been brought about by the the development of digital imaging modalities. The clinical application of these modalities for tuberculosis can be carried out in various situations, screening, differential diagnosis, examination for disease extend, marker of treatment response and checking the sequela. A digital image processing of contrast adjustment using Fuji Computed Radiography (FCR) produce more favorable chest image than that of spacial frequency enhancement. From our experience FCR proved superior to conventional film-screen system. CT has been considered to be very useful for detection and observation of tuberculosis lesion. Recently thin slice CT and high resolution CT have improved spacial resolution and these modalities are very useful to differentiate peripheral pulmonary nodule. Magnetic Resonance Imaging (MRI) completely differs from X-ray examination in terms of image parameter. The histologic resolution of this image is superior to any X-ray examination and Gd-DTPA enhancement will assist the differential diagnosis of nodular lesion. On the contrary, the spacial resolution of this chest imaging is inferior to CT because of respiratory motion. However, MRI application for brain is useful in diagnosis of cerebral tuberculosis. A spiral CT scanning has been developed for clinical use and three dimensional CT (3-D CT) can be obtained by this system.(ABSTRACT TRUNCATED AT 250 WORDS)

[Role of MR imaging in the diagnosis and evaluation of sarcoidosis].

In the diagnosis of mediastinal and/or hilar lymphadenopathy in patients with sarcoidosis, MR (magnetic resonance) imaging is similar to CT in its ability to detect these lesions. Values of T1 and T2 of lymph nodes of sarcoidosis do not appear to differ from those of other diseases. The T1-weighted images are most helpful in distinguishing swollen lymph nodes from fat tissue and in defining vascular anatomy. Using the coronal or sagittal plane, MR imaging is more able to demonstrate subcarinal or aorticopulmonary nodes better than CT. However, it is inferior to CT in the evaluation of the pulmonary parenchymal involvement of sarcoidosis. On the other hand, in the diagnosis of CNS sarcoidosis and nodular type muscular sarcoidosis, MR imaging should be applied as the primary imaging modality. The use of Gd-DTPA increases the sensitivity of MR imaging in the detection of CNS sarcoidosis, especially, in patients with meningeal involvement. Both T1- and T2-weighted axial spin-echo images show specific findings in patients with the nodular type of muscle lesions.

Effect of chlormadinone acetate on ventilatory control in patients with chronic obstructive pulmonary disease.

Twelve patients with chronic obstructive pulmonary disease (COPD) were studied to determine the effect of ventilatory stimulation with chlormadinone acetate (CMA), a potent synthetic progesterone, on chemical and neuromechanical respiratory controls and pulmonary gas exchange. Using a randomized, double-blind, cross-over trial, 1 wk of CMA therapy caused a significant reduction in arterial CO2 tension (Paco2) by 4.6 +/- 0.6 (SE) mmHg. This Paco2 fall was associated with increased minute ventilation (Vl), tidal volume (VT), and mean inspiratory flow (VT/Tl). During CMA administration, occlusion pressure response to CO2 with and without inspiratory flow-resistive loading increased significantly (p less than 0.01) over that during placebo administration, whereas ventilatory response to CO2 did not. In addition, normocapnic ventilatory and occlusion pressure response to hypoxia were significantly elevated (p less than 0.01) during CMA therapy. Furthermore, the degree of load compensation, which was assessed by the ratio of the loaded to unloaded slope in the occlusion pressure response to CO2, increased in all subjects after CMA administration. These results indicate that CMA augments not only the respiratory neuromuscular response to hypercapnia and hypoxia, but also flow-resistive load compensation in patients with COPD, and it may provide support for the use of CMA in patients who are able to decrease their Paco2 with this agent.

[Relationship between signal intensity of blood flow in the pulmonary artery obtained by magnetic resonance imaging and results of right cardiac catheterization in patients with pulmonary disease].

Electrocardiogram-gated spin-echo magnetic resonance (MR) images of the chest were obtained in five normal controls and 35 patients with pulmonary disease (11 chronic obstructive pulmonary disease, 6 pulmonary thromboembolism, 5 primary pulmonary hypertension, 4 interstitial pulmonary disease, 4 pulmonary hypertension with disturbance of portal circulation, and 5 other diseases) who underwent right cardiac catheterization. In transverse images at the level of the right main pulmonary artery (rPA) and sagittal images at the level through the midsternal line and the spinal chord, the signal intensity of blood flow in the rPA was quantitatively evaluated, and the correlations with the MR signal intensity of intravascular flow and the parameters of hemodynamics were studied. In diastole MR images of both normal controls and patients mostly showed a significant signal intensity of flowing blood, but in systole some patients demonstrated significant signals and visible flow images. In systolic MR images, the mean values of hemodynamic parameters (mean pulmonary arterial pressure (mPAP), pulmonary arteriolar resistance (PAR), and cardiac index (CI)) were abnormal in patients with significant signal intensity of flow compared with those in patients without sufficient MR signal. The signal intensity was not correlated with mPAP; however, it significantly increased as PAR increased, and it increased as CI decreased both in diastole and in systole. Especially in systole, there was good correlation between the signal intensity in transverse MR images and CI (r = -0.85, P less than 0.01) and between signal intensity in sagittal MR images and PAR (r = 0.90, P less than 0.01). These results suggest that significant flow signal in the rPA in systole has pathophysiological significance, and signal intensity is considered to be significantly affected by changes of PAR and CI. The signal intensity of blood flow in the rPA on MR images can be used as an index of the severity of right heart failure associated with pulmonary disease. MR imaging is a useful modality to evaluate pulmonary circulation disturbance because of its ability to assess blood flow in the pulmonary artery noninvasively without interference from other structures such as bone and normal lung.

[Correlation of signal intensity of blood flow in the pulmonary artery on MR images and clinical features of two cases of primary pulmonary hypertension].

ECG-gated spin-echo MR images of the chest were obtained in two patients with primary pulmonary hypertension (PPH). In transverse section at the level of the right main pulmonary artery (rPA), flow signals in the rPA were quantitatively evaluated, and the correlations with MR signal intensity of intravascular flow and data of routine clinical examinations and the severity of clinical manifestations were studied. In one case, the signal intensity of flowing blood markedly increased with exacerbation of hypoxemia and other clinical manifestations. However, in the other case with a stable course, the signal intensity of intravascular flow did not change significantly. Increase of flow signal in the rPA can reflect decrease of flow velocity that may be cause by a state of high pulmonary vascular resistance or low cardiac output. Therefore, it is suggested that MRI is a useful modality to evaluate the severity of disturbance of the pulmonary circulation in PPH.