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Background As one of the most rapidly ageing economies, Japan is currently faced with a shortage of care workers and relatively low intakes of migrant workers. While there is a shortage of health and social care professionals, the retention of professional staff is paradoxically becoming more difficult. The environment in domiciliary care is often associated with heavy and challenging workload. Robotics-aided care has been proposed in Japan to ameliorate the situation. While some positive effects of such a novel care model have been reported, the mechanism by which the technology-driven system improved care and residents’ quality of life remains unclear. Methods Using a case study approach, this paper examines one of the nursing homes in Japan where robotics-aided care was introduced. The organisational mechanism was analysed through documents and semi-structured staff interviews from the perspective of safety science. The key attributes of organisational resilience are: anticipating; responding; monitoring and learning. The paper details some of the tools that predated the introduction of the socially assistive robots and monitoring system in the care home. The interviews were conducted with 16 health and social care professionals. Results The results of the technological intervention itself demonstrated improved scores for the quality of life among the residents. However, the subsequent interview data highlight the significance of an organisational context in which technologies can be effectively introduced and implemented in nursing homes. The organisation had several well-trained care professionals, including the leaders, who share the mental map of ‘person-centred care’ and the ‘capability approach’. In addition, some tools were used to ‘visualise’ staff practice. Health and social care professionals pointed out some challenges surrounding the human-technology interface. Conclusion In order to understand the effectiveness and potential issues of the ICT robotics solution in care for older people, future research should investigate the human-technology interface and the interconnectedness between work system, care processes and outcomes.

This study is aiming to develop a low power consumption 4 K G-M cryocooler. As a first step, a two-stage G-M cryocooler with a 2 kW class compressor has been tested. The base model of cold head of two-stage G-M cryocooler is RDK-305D (Sumitomo Heavy Industries). We modified its second stage regenerator materials by filling magnetic materials Gd2O2S and HoCu2 spheres. An air-cooled compressor of SA115 (ULVAC CRYOGENICS) that rated input is 1.9 kW at 60 Hz was connected to the cold head. The experimental results showed that the cooling capacity of the second stage of 0.5 W at 4.2 K and the first stage of 25 W at 45 K was achieved with the cold head reciprocating speed of 48 rpm and the compressor electrical input of 2.09 kW. The relative Carnot efficiency of 1.7% at 4.2 K was calculated from the result. A low reciprocating speed of 48 rpm was chosen is to secure the sufficient expansion work in the second expansion space. This is considered an effective method to obtain a large cooling capacity at 4 K by low power compressor.

Introduction Because the population is aging, the indication for surgical reconstruction in older patients will increase. Japan is especially facing the most aging society worldwide. However, surgical reconstruction of type A aortic dissection (AADA) in patients who are octogenarians is not often performed because of the decision of the patient or surgeon. We examined the outcome of surgical reconstruction of AADA in octogenarians. Method Over 4 years, 132 cases of surgical reconstruction of AADA were analyzed. Twenty-five consecutive octogenarians with AADA were retrospectively reviewed. In our institution, we recommend an emergent operation to the patient or family in all generations unless they reject it for some reason. Results Operative factors in octogenarians with AADA were not significantly different compared with those in patients aged younger than 79 years (n=107) (operation: 238±11 vs. 246±5 min, p=0.54; cardiopulmonary bypass: 147±7.4 vs. 154±3.5 min, p=0.42; aortic-clamp: 114±6.0 vs. 120±2.8 min, p=0.36; hypothermic-arrest: 43±2.7 vs. 42±1.3 min, p=0.81). The overall mortality rate was 24.0% (n=6). The mortality rate was no difference between younger patients and octogenarians (OR: 2.7, 95% CI: 0.86–8.21, p=0.08). Furthermore, MACE (Major Adverse Cardiac Event) and the postoperative stroke rate were not significantly different between the two groups (OR: 1.5, 95% CI: 0.52–3.93, p=0.42; OR: 0.77, 95% CI: 0.16–2.59, p=0.69, respectively). Conclusion In AADA, the outcome of emergent surgical reconstruction in octogenarians is acceptable. Even with the risk of aging, surgeons should consider aggressive surgical reconstruction in octogenarians.

Advanced regenerator materials of erbium and holmium binary nitrides, Er x Ho1-x N (x = 0 - 1) were studied. Its specific heat vs. temperature curve, possesses a peak due to the magnetic phase transition at their Curie temperature. The cooling power at 4.2 K of a commercial 4K-GM cryocooler filled with the binary nitride of x = 0.625, 0.75, 0.875 or 1 was evaluated. It was found that the cooling power at 4.2 K has a good linear correlation with the heat quantity, which is calculated by integrating C with respect to T in the region of 4.2 - 7.0 K. Three binary nitrides (x = 0.625, 0.875 and 1) filled in series along the regenerator column gave 26% higher cooling power than that filled with HoCu2.

This paper presents the experimental results of 4.2 K cooling power of a Gifford-McMahon (G-M) cryocooler. To improve the cooling power, an original regenerator structure named coaxial pipe regenerator was applied to the second stage regenerator. This structure is that a stainless steel pipe is inserted in the coaxial direction of the second stage regenerator. An effect of the coaxial pipe is considered to rectify the helium flow in the regenerator that leads to an increase in the mass flow rate to the expansion space. Then, an improvement in the cooling power is expected. The second stage regenerator is comprised of three-layer of Pb (warm side), HoCu2 (middle) and Gd2O2S (cold side) spheres of which the volume filling rate is 50, 20 and 30%, respectively. The coaxial pipe is applied to each material layer independently to survey an improvement effect of the cooling power at 4.2 K. These coaxial pipe regenerators were tested with a G-M cryocooler of one-watt model (RDK-408D2, SHI) and a scroll-type compressor (SSC-3700, SUZUKISHOKAN). The three-layer regenerator (without coaxial pipe) obtained the cooling power of 1.70 W. When the coaxial pipe was applied to the Pb layer, the cooling power of 1.79 W was achieved with the electrical input of compressor of 7.06 kW. In contrast, the coaxial pipe of HoCu2 layer and Gd2O2S layer showed no conspicuous improvement. These results prove that the flow condition of helium in the Pb layer significantly affects the 4 K cooling power.

Tungsten–rhenium (W–Re) thermocouples are widely used in industry for measurements at high temperatures, up to $$2000\,^{\circ }\hbox {C}$$ . Since the electromotive force (emf) of a W–Re thermocouple is known to change during exposure at high temperatures, evaluation of the emf stability is essential for measuring temperature precisely and for realizing precise temperature control used to ensure the quality of products subject to annealing processes. To evaluate precisely the thermoelectric stability around $$2000\,^{\circ }\hbox {C}$$ , two Ru–C $$(1953\,^{\circ }\hbox {C})$$ cells (crucible and Ru–C eutectic alloy) were constructed in our laboratory. The key feature of the cells is that their dimensions are large to ensure there is sufficient immersion available to evaluate the homogeneity characteristics of the thermocouples. By using one of the Ru–C cells, the drift and inhomogeneity of Type C (tungsten–5 % rhenium vs tungsten–26 % rhenium) thermocouples during an exposure to high temperature around $$2000\,^{\circ }\hbox {C}$$ were evaluated. Furthermore, to explore possible applications of the eutectic point to other types of high-temperature thermocouples, the drift of an IrRh/Ir thermocouple (iridium–40 % rhodium vs iridium) was also evaluated using another Ru–C cell. The tests with W–Re and IrRh/Ir thermocouples demonstrate that the newly developed Ru–C cells can be used to successfully realize melting plateaux repeatedly. This enables the long-term drift measurements essential for the evaluation and improvement of high-temperature thermocouples. The results obtained in this study will also be useful for evaluating the uncertainty of thermocouple calibrations at around $$2000\,^{\circ }\hbox {C}$$ .

There exists various research reports concerning the evaluation methods for the measurement uncertainty due to inhomogeneity of thermocouples; however, the universal method is still waiting to be established. This article considers the evaluation methods for the measurement uncertainty due to inhomogeneity of thermocouples based on comparison between results of two measurement methods. The first method is to estimate the uncertainty from the immersion characteristics of a thermocouple within a fixed-point furnace during its realization. The second method is to estimate the uncertainty from the immersion characteristics of a thermocouple within a heat-pipe furnace with a long uniform region. A pressure-controlled water heat-pipe furnace with an immersion depth of 1000 mm is developed to enable this work. It overcomes the technical difficulties that existed in applying conventional sealed heat pipes to such applications. From the immersion characteristics of a thermocouple measured by the above two methods, we have introduced three measurement parameters. Estimating the measurement uncertainty due to the inhomogeneity from our measurement results as examples is discussed.

We propose a resolution improvement technique for a high-density array of walled linearly tapered slot antennas (LTSAs) in ground-penetrating radar imaging. In the system, we use the walled-LTSA array in a near-field measurement configuration and select various pairs of transmitter and receiver antennas out of the array elements. We prepare four selection modes so that we can practically enhance the imaging resolution. We remove the direct-coupling effect and compensate the path-length fluctuation caused by element individuality and element selection. Experiments demonstrate that the technique realizes higher resolution image acquisition to yield a clearer segmentation of antipersonnel plastic landmines in combination with adaptive image processing, based on complex-amplitude texture, even on a wet laterite soil condition.

We propose a walled linearly tapered slot antenna (LTSA) array to visualize plastic landmines. Previously, we reported an adaptive nonlinear visualization system based on a complex-valued self-organizing map (CSOM) that deals with complex amplitude texture in reflection images at multiple frequencies. The system distinguishes landmines from clutter by paying attention to textural features obtained by high spatial resolution and wideband reflection measurement. Because the system employed a mechanical scan of a pair of horn antennas, the measurement required a long time. An array antenna can reduce the time. The antenna element to be used there should therefore be compact and wideband. This paper reports the design and fabrication of a walled LTSA array visualization system. The antenna element has a 14 times 28 mm aperture size, and works at the 8-12 GHz frequency band. Because the structure is a simple combination of glass epoxy substrates and metal plates, we can easily fabricate low-cost and lightweight arrays. Electrical switches realize a high-speed scanning of 12 times 12 = 144 elements in total. We also report the results of a visualization experiment, in which plastic landmines are clearly visualized with the array in combination with the adaptive CSOM processing. Detection of landmines at frequencies of 10 GHz is only likely to be possible for targets buried a few centimeter deep or where the soil attenuation is very low. This might be a severe limitation of applicability of the method, as in field conditions soil attenuations of 10 dB or considerably more are commonly encountered, requiring the radar to operate at frequencies below 2-3 GHz. The best solution may be a multisensor system comprising these complementary high- and low-frequency radars.

This paper focuses on the second stage regenerator of a 4 K Gifford-McMahon (G-M) cryocooler. A three-layer layout of lead (Pb), HoCu2 and Gd2O2S spheres in the second stage regenerator derives a good performance at 4 K. After some modifications, we confirmed that the cooling power of 1.60 W at 4.2 K was achieved by using this three-layer layout. A two-stage G-M cryocooler is RDK-408D2 (SHI) and a compressor is C300G (SUZUKISHOKAN) with a rated electric input power of 7.3 kW at 60 Hz. In order to further improve, a double pipe regenerator was applied to the second stage regenerator. As a double pipe, a stainless steel pipe with thin wall was inserted in the coaxial direction into the second stage regenerator. The helium flow in the second stage regenerator is expected to be non-uniform flow because of the distribution of helium density and the imperfect packing of regenerator material. The double pipe regenerator is considered to have an effect of restraining the non-uniform flow. From the experimental results, the second stage cooling power of 1.67 W at 4.2 K and the first stage cooling power of 64.9 W at 50 K were achieved.

High purity erbium nitride (ErN) spheres with the size range of 150-180 µm and 180-212 µm were prepared by nitriding Er metal spheres with low oxygen content. The initial regenerator material of HoCu2 on the cold end of the second regenerator column in 4K-GM cryocooler with nominal cooling power of 0.1 W at 4.2 K was replaced by ErN with different sizes. Higher cooling power was obtained when ErN of smaller size with lower oxygen content was used. We investigated the effect of partial replacement of HoCu2 by ErN in the cold end side of second stage regenerator column on cooling power of 4K-GM cryocoolers. When ErN were substituted for 20 % of HoCu2, the cooling power at 4.2 K reached 0.318 W. This value was 1.36 times as high as that of the cooling power of the GM cryocooler with commercially available regenerator arrangement. Therefore, use of ErN regenerator materials leads to the energy-saving and downsizing of 4K-GM cryocoolers.

Magnetic regenerator materials, such as HoCu2, Er3Ni, Gd2O2S, and so on, are always needed to produce the cooling power at the temperature of 4.2 K using regenerative cryocoolers. The use of a large quantity of magnetic regenerator materials affects directly the fabrication cost of 4K cryocoolers. From this point of view, we introduce a magnetic regenerator material economizing method in this paper. An innovative regenerator structure was adopted for two-stage Gifford-McMahon (GM) cryocooler. The structure has a bakelite rod inserted in the co-axial layout of the 2nd stage regenerator in which HoCu2 spheres are filled. The cold temperature side of the 2nd stage regenerator is occupied with 50% by volume of the bakelite rod and HoCu2 spheres, and the warm side is packed with lead (Pb) spheres as a single layer. The bakelite rod is a dummy volume. Two types of conventional GM cryocoolers with power consumption of 1.3 and 7.3 kW, respectively, are tested. The experimental results show that the filling volume...

Honda, Y., H. Tani, A. Masuda, T. Kobayashi, T. Nishino, H. Kimura, S. Masuyama, and T. Kuriyama. Effect of prior O2 breathing on ventilatory response to sustained isocapnic hypoxia in adult humans. J. Appl. Physiol. 81(4): 1627–1632, 1996.—Sixteen healthy volunteers breathed 100% O2 or room air for 10 min in random order, then their ventilatory response to sustained normocapnic hypoxia (80% arterial O2saturation, as measured with a pulse oximeter) was studied for 20 min. In addition, to detect agents possibly responsible for the respiratory changes, blood plasma of 10 of the 16 subjects was chemically analyzed. 1) Preliminary O2 breathing uniformly and substantially augmented hypoxic ventilatory responses. 2) However, the profile of ventilatory response in terms of relative magnitude, i.e., biphasic hypoxic ventilatory depression, remained nearly unchanged. 3) Augmented ventilatory increment by prior O2 breathing was significantly correlated with increment in the plasma glutamine level. We conclude that preliminary O2administration enhances hypoxic ventilatory response without affecting the biphasic response pattern and speculate that the excitatory amino acid neurotransmitter glutamate, possibly derived from augmented glutamine, may, at least in part, play a role in this ventilatory enhancement.

Asplenium nidus is an epiphytic fern with large simple leaves. Because A. nidus lacks the good taxonomic characters available for species recognition, multiple cryptic species may exist within A. nidus. In Mt. Halimun National Park, West Java, Indonesia, three rbcL sequence types of A. nidus were recorded. All plants regardless of rbcL sequence were 2n = 144. Crossing experiments among these rbcL types were conducted, and it was observed that the molecularly distinct types were reproductively isolated because hybrids failed to form between at least two pairs of rbcL types. These results suggest that these rbcL types are cryptic species because they are reproductively isolated but they are difficult to distinguish morphologically. Thus, the characters of DNA sequences information are useful in the discovery of cryptic species in ferns.

We describe the importance of ultra wideband (UWB) reflection measurement in the adaptive target visualization. We use a complex-valued self-organizing map (CSOM) to deal with complex-amplitude texture obtained by stepped-frequency UWB reflection measurement. We distinguish targets from clutter by paying attention to the difference in texture in space and frequency domains. In the technique, a wideband measurement is desirable to obtain precise texture. We employ a newly developed antenna, walled LTSA, with which we can construct a wideband, dense array for high-resolution imaging.

A phase shifter, which controls the phase angle between the mass flow and the pressure, plays a key role in the performance of a pulse tube refrigerator. The purpose of this paper is to examine the influence of an active phase controller (APC) instead of using inertance and buffer as a phasor. An electrically driven and mechanically damped linear compressor, which is directly connected at the warm end of the pulse tube using a connecting tube, is used as the APC. Therefore, this Stirling type active phase control pulse tube refrigerator (APCPTR) has no reservoir. The advantage of this phase shifter is that it is easy to control the electric input power and the phase angle. Also, the APCPTR is able to operate at any desired temperature region or condition. In order to clarify the characteristics of APCPTR, the cold end temperature and power consumption of the APCPTR has been measured.

Acute myocardial infarction, as a result of coronary malperfusion caused by acute type A aortic dissection, has been identified as one of significant factors relating to operative mortality. This complication could be diagnosed with a combination of electrocardiography and echocardiography in acute phase. However, the indication of coronary angiography and/or intervention has been controversial as it is time-consuming and renders additional stress to a critical patient requiring an emergency operation. We report a case of myocardial infarction successfully treated with percutaneous transluminal coronary angioplasty (PTCA) at first, after that, recognition of dissection of aorta necessitated subsequent surgical therapy. In this particular case, coronary intervention in advance proved to be mandatory.

We investigated the effect of state-specific changes associated with REM sleep on pulmonary artery pressure in patients with obstructive sleep apnea (OSAS). Six male patients with OSAS (age; 40 +/- 12 SD yrs, BMI; 39.0 +/- 8.6 kg/m2, AHI; 51.5 +/- 28.5) were examined throughout the night by polysomnography, while monitoring pulmonary artery pressure via right cardiac catheterization. All patients had pulmonary hypertension (PH) during periods of wakefulness, and their mean pulmonary artery pressure (PAPm) was 31.1 +/- 7.4 mmHg. PAPm was analyzed at two different points in each apneic episode. PAPbase was the baseline value when inspiratory effects during apnea were not elicited, and PAPpeak was the peak value observed just after the cessation of OSA. PAPpeak was higher in REM (56.3 +/- 12.4) than in NREM (41.4 +/- 6.9 mmHg; P0.01), and both values were significantly higher than those observed during periods of wakefulness. The magnitude of elevation of PAP (delta PAP; PAPpeak-PAPbase) in REM and NREM were 11.6 +/- 2.0 and 6.9 +/- 2.8 mmHg, respectively. Relative ratios in the response of PAP to a decrease in O2 desaturation (delta PAP/delta SpO2) showed almost the same value for REM (-0.57 +/- 0.27) and NREM sleep (-0.57 +/- 0.26 mmHg/%). The values of PAPm at SpO2 75% were significantly higher in REM than in NREM (48.7 +/- 11.2 vs. 41.6 +/- 6.2 mmHg). We conclude that transient pulmonary hypertension could be caused not only by hypoxia, but also by state-specific responses (which are unrelated to hypoxia) that occur during REM sleep.

The carotid body (CB) is the most important chemoreceptor for eliciting hyperpnea in response to hypoxic exposure.1 However, the level of hypoxic hyperventilation is not maintained at a constant level: ventilation (VI) during sustained mild hypoxia initially increases rapidly, and then gradually declines with time.2-4 The initial rapid rise is generally considered to be induced by CB excitation, whereas the mechanism for the subsequent gradual decline (hypoxic ventilatory decline, HVD) is a matter of controversy.5-9 It has also been confirmed in humans as well as in other animal species that the magnitude of the initial ventilatory increment is closely correlated with secondary HVD.10-13 Fig. 1 illustrates an example of such a finding previously obtained by us.13 This fact led us to assume that this specific profile of hypoxic hyperpnea is possibly entirely related to the CB activity. Therefore, we intended to study CB-resected patients who underwent a therapeutic surgery for bronchial asthma some 40 yrs ago. We found that these patients revealed no HVD.

We experienced a 27-year-old male patient with recurrent hemoptysis manifested by granuloma which resulted from surgical repair that was performed for right pneumothorax using unabsorbable sutures (braided silk) before 10 years. The patient had been suffering from fever and cough for three months before hemoptysis. Chest X-ray and CT scan films showed a mass shadow in the lateral side of the right lung field. Furthermore, bronchoscopy revealed bleeding in B3 of the right lung. The patient underwent right upper lobectomy, which disclosed that hemoptysis was due to a granuloma (2.3 x 3.2 cm in size) formed around sutures. The granuloma was caused not only by foreign body reaction but also by transbronchial infection.

The prevalence of sleep apnea syndrome (SAS) in Japan has been reported to be about 1-2%, which is almost the same as that reported in western countries. However, an epidermiological survey of SAS recently performed by institutes participating in the Japanese Society of Sleep-Disordered Breathing showed that only 1,425 patients were newly diagnosed in 1993, which suggests that there are many latent or undiagnosed cases in Japan, because SAS is newly diagnosed in 75,000 patients every year in the USA. Here we reported on issues related to the diagnosis and treatment of SAS in Japan and in other countries.

Patients with obstructive sleep apnea syndrome (OSAS) may have daytime pulmonary hypertension (PH). Transient and sometimes severe elevations of pulmonary arterial pressure during sleep as a result of intermittent upper airway obstruction may lead to daytime PH. We sought to study the factors involved in the development of daytime PH. Right-heart catheterization, pulmonary function tests, and arterial blood gas measurements were done in 25 patients in whom OSAS was diagnosed by whole-night polysomnography. Eight of the patients (32%) had PH, defined by a mean pulmonary arterial (PA) pressureor = 20 mmHg. For the group as a whole, mean PA pressure was positively and significantly correlated with daytime PaCO2 (r = 0.79), percent of ideal body weight (r = 0.45), and Hb (r = 0.40). Mean PA pressure was negatively and significantly correlated with PaO2 (r = -0.54), FEV 1% (r = -0.52), and %FVC (r = -0.68). In contrast, mean PA pressure was not significantly correlated with apnea index or with sleep desaturation. These data indicate that daytime PH was not directly related to sleep-disordered breathing, but was related to daytime hypoxemia, daytime hypercapnia, obesity, obstructive and restrictive respiratory impairments, and secondary polycythemia.

Excessive daytime sleepiness (EDS) in certain patients with sleep apnea syndrome may be the result of intermittent upper airway obstruction during sleep. The possible occurrence of daytime hypertension and pulmonary hypertension (PH) in these patients has been emphasized. Transient and sometimes severe elevations of systemic and pulmonary arterial pressures during sleep as a result of intermittent upper airway obstruction may lead to EDS, daytime hypertension, and PH. The aim of the present study was to investigate whether daytime hypoxemia and hypoxemia during sleep contribute to EDS, daytime hypertension, and PH. The results indicate that: (1) sleep disturbance and blood gas changes while awake and asleep may play a role for EDS, although these abnormalities were not present in some cases, (2) hypoxemia while awake and asleep is probably not involved in daytime hypertension, and (3) mean resting pulmonary arterial pressure is correlated with daytime PO2, PCO2, %IBW, %FVC, and FEV1.0%, Cardiopulmonary hemodynamic function may return to normal in some patients who receive appropriate treatment.

A 23-year-man with morbid obesity and obstructive sleep apnea syndrome (OSAS) was admitted. He was 170 cm in height and 170 kg in weight. He underwent dietary treatment several times, but his weight returned to its original level, or even higher, within a short period. A diagnosis of OSAS was made by nocturnal polysomnography. In this morbidly obese patient with OSAS a nocturnal sleep apnea study was performed before and after weight reduction surgery (gastric restriction). The postoperative findings revealed a dramatic body weight reduction. At the same time, the results of apnea and oxygen desaturation were remarkably improved too. These results indicate that weight reduction surgery is a definitely effective treatment for morbid obesity associated with OSAS.

A simulation model of evaluating deployment strategies for fire engines is introduced in this paper. Expected burned-area was adopted as a criterion. This simulation model was implemented by using the data of Kyoto City. First this simulation model is demonstrated to be valid by comparing the results derived by executing simulations on this model with the actual data of Kyoto City in five years (1974 - 1973). Then, three alternative strategies are compared by this model. From these results, it becomes clear that about 30% reduction of burned-area in one year is expected by an alternative deployment strategy which will be feasible by introducing the computer-aided command and control system of fire engines.

Somatosensory evoked potentials were recorded in 53 patients with cervical myelopathy due to spondylosis (32) or ossification of the posterior longitudinal ligament (21). The overall abnormality rate was 68 per cent, and slightly higher in OPLL. P14 and N18 components were the most often affected, even in less severe cases, but the P23 and N30 components correlated well with the severity of myelopathy.

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.

To investigate the changes of testosterone (T) secretion under sustained hypoxia, we determined basal levels of urine T, 17 ketosteroid, luteinizing hormone releasing hormone (LHRH), luteinizing hormone (LH), follicle stimulating hormone (FSH) and response to LHRH and HCG (human chorionic gonadotropin) in male patients with respiratory failure. After evaluating blood gas data, we also measured serum T, LH, FSH, plasma progesterone (P) and 17 hydroxyprogesterone (17OH-P). The subjects were divided into 3 groups according to PaO2; Group 1 with a PaO2 under 60 Torr, Group 2 with a PaO2 between 60 Torr and under 70 Torr, Group 3 was an age-matched control group. Urine T and serum T were significantly lower in Group 1 compared with those of Group 3. In the LHRH test, augmented relative responsiveness and delayed peak value in LH secretion were observed in Group 1, compared with those of Group 3. As for the HCG test, no differences were observed among the 3 groups. The ratio of 17OH-P to P, which indicates activity of 17-hydroxylase, was observed to be diminished with increasing degrees of hypoxia. These data suggest that in male patients with respiratory failure there was depression in T secretion as well as 17-hydroxylase activity due to hypothalamic-pituitary hypofunction.

Spinal cord evoked potentials were recorded from the cervical or thoracic epidural space following spinal cord stimulation in 21 patients with cervical spondylotic myelopathy, 18 with ossification of the posterior longitudinal ligament and 7 with spinal cord injury due to fracture-dislocation. Thirteen cases were monitored during surgery. Amplitude or waveform abnormalities were detected in the majority of cases, and could often be used to determine the affected vertebral levels. Amplitude was sometimes greatly increased after decompressive surgery.

Home oxygen therapy is now considered indicated in cases of severe sleep oxygen desaturation. To explore whether we could choose cases with severe sleep desaturation by measurement of waking physiological parameters, we examined the relationship between arterial blood gases, lung functions and pulmonary artery pressure while awake and the degree of sleep oxygen desaturation in 21 patients with chronic obstructive pulmonary disease and 22 cases with a past history of pulmonary tuberculosis. There were significant correlations between waking PaO2, PaCO2 and pulmonary artery mean pressure and sleep lowest SaO2, respectively, whereas no significant relation was found between %VC or FEV1.0% and sleep lowest SaO2. However, we found wide ranges of PaO2 and PaCO2 in cases who had 10 min or more with SaO2 below 85% during sleep. This was also true in the patients who underwent 60 min or more with SaO2 below 85% while a sleep. These results suggest that it may be difficult to find out the indications for cases with severe sleep desaturation by evaluation of arterial blood gases while awake.

We studied the influence of hypoxia due to sleep apnea on testosterone (T) secretion. It was conducted on the basis of an idea that sustained hypoxia may depress T secretion. The subjects consisted of 15 male patients with no drug administration whose complaints were snoring and/or obesity. The subjects participated in a sleep study on two consecutive nights. During the first night we collected blood samples starting every 4 hours from 10 PM via a catheter and measured T. From the data of the second night, we calculated total desaturation time with more than 4% from the baseline SaO2. According to the amount of this desaturation time, the subjects were divided into 2 groups; desaturation time less than 80 min in group 1 and longer in group 2, respectively. The peak value was seen at 6 AM in group 1 and at 10 AM in group 2. We investigated the correlation between the ratio of T10/T6, which is the ratio of T level at 10 AM to that at 6 AM, and parameters of sleep disorders related to oxygen desaturation. Total 4% desaturation time in total sleep period and non REM period significantly correlated with this ratio. From the diagram illustrating the correlation between the ratio and total 4% desaturation time in total sleep period, we could assume that if the ratio is beyond 1, the subject may have had more than about 80 min of total 4% desaturation time.