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Biomedical subjects

S Sagawa

Publications and source records attributed to S Sagawa.

At least 73 records · Page 4Linked to original sources
PubMed1987

Seadragon VI: a 7-day dry saturation dive at 31 ATA. VII. Erythrocyte functions.

Organic phosphates and the Donnan ratio (cell to plasma Cl ratio) were measured in man during a dry saturation dive to 31 ATA for 7 d. 2,3-DPG increased significantly with a concomitant decrease in ATP and the molar ratios of ATP and ADP on Day 5 at 31 ATA (P less than 0.05). Inorganic phosphate did not change during the dive. The Donnan ratio was relatively high at 31 ATA and the value was significantly different on Day 3 at 31 ATA (0.731 at 1 ATA vs. 0.895 at 31 ATA, P less than 0.05). This suggests a rise in intracellular pH, resulting from a change in the net charge of hemoglobin. It is speculated that an increase in oxygen affinity of hemoglobin occurs during the early phase at 31 ATA and is followed by an increase in 2,3-DPG in response to the resulting tissue hypoxia.

Adenosine Diphosphate↗
PubMed1986

Heat stress: a threat to health and safety.

This review offers a rational basis for the use of fundamental physiological controlling mechanisms in setting safe environmental limits for occupational situations where heat stress is encountered. There is no single index of heat stress that has been universally accepted. However, the use of wet bulb glove temperature (WBGT) has been adopted by various organizations on occupational health and safety in several industrial countries. Thermal limits suggested for everyday work continue to be subject to argument. The controversies arise from the fact that many factors such as individual variations, acclimatization, clothing, age, sex, physical fitness and work load lead to significant effects on tolerance of man to heat. Several measures for prevention of heat stress under industrial situations are summarized briefly. There is no agreement on a single measure to be used, rather a combination of these measures can be the most effective mean to alleviate or prevent severe heat stress. It is to be hoped that this review may help public health officials and medical doctors of various work occupations resolve some of the problems that arise in setting thermal limits and preventive measures, thus contributing to increase productivity and efficiency of work.

Acclimatization↗
PubMed1986

Thermoregulatory responses of the elderly population.

With a significant rise in the elderly population of the developed industrialized countries due to increased life span the harmful consequences of heat and cold stresses are expected to be more notable. Although effects of these harmful stresses on morbidity and mortality of the elder population are well documented in medical reports, relatively few studies are notable for the investigation of age-related effects on thermoregulation. In this report, data on responses of older individuals to heat stress during rest and exercise are summarized. When old men (60-86 years) were exposed to 40 degrees C and 40% relative humidity for 2 hr during rest, their total body sweat rate/m2 (SR) was similar to the young group (20-35 years). The onset of sweating was also similar in both groups. Regional SR was not uniform in either age group. Since the responses of both groups were similar, data were pooled to examine the relationship between age and physical fitness, as measured by aerobic capacity (VO2 max), to physiological responses. Only VO2 max and body fat were significantly related to age. The SR was related to fitness. When old men and women walked at a level costing 40% of their VO2 max in desert heat for 1 hr, total SR was similar in all age groups. The efficiency of walking was similar in young and old, but the least fit individuals were less efficient. In all our studies, the data clearly indicate that age per se does not decrease the functional capacity of the sweating mechanism and that problems encountered by the elderly in hot environments are primarily related to impairment of the cardiovascular functions.

Age Factors↗
PubMed1986

Cardiorenal-endocrine responses to head-out immersion at night.

Cardiorenal-endocrine responses to 3-h head-out immersion (HOI) (water temperature = 34.5 +/- 0.5 degrees C) were studied during day (0900-1400 h) and night (2300-0400 h) in six hydropenic male human subjects. Although HOI induced a reversible increase in urine flow in all subjects, the response was faster and greater in magnitude during the day compared with night (P less than 0.05). Na excretion and osmolal clearance (Cosm) also followed the identical response pattern as urine flow, and in fact, the HOI-induced diuresis was entirely accounted for by the increased Cosm. Endogenous creatinine clearance was not different between the day and the night and remained unchanged during HOI. Both plasma renin activity and aldosterone concentration and urinary aldosterone excretion were nearly twofold greater during the day compared with night before HOI but decreased to the same level during HOI in both daytime and the nighttime series (P less than 0.05). There was no correlation between the Na excretion rate and renin-aldosterone levels either before or during HOI. Plasma antidiuretic hormone (ADH) level was comparable between day and night before HOI and decreased to a similar level during HOI in both daytime and nighttime series (P less than 0.05 for nighttime HOI). Cardiac output increased from 3.3 1/min before HOI to 5-6 1/min during HOI without showing any significant circadian difference. Hematocrit, hemoglobin, and plasma concentrations remained unchanged under all conditions. It is concluded that the renal response to HOI is subject to nocturnal inhibition, which cannot be attributed to circadian differences in the degree of HOI-induced central blood pooling, renin-aldosterone, or ADH responses.

Adult↗
PubMed1986

Cutaneous vascular responses to heat simulated at a high altitude of 5,600 m.

Six healthy young men were studied in a high-altitude chamber during a 60-min heat exposure at a simulated altitude of 5,600 m or 0.5 atmosphere absolute (ATA). The heat load was provided by increasing the chamber temperature to 38 degrees C at the rate of 1 degree C/min after a 60-min equilibrium period at thermoneutrality (28 degrees C). Our question was whether or not hypoxia causes differential changes in regional cutaneous circulation during heat exposure. Skin blood flow in the forearm (FBF) and the finger (FiBF), temperatures of the esophagus (Tes) and of the skin, and cardiac output (CO) were measured during the heat exposure at 0.5 ATA and at the sea level (1 ATA). During the equilibrium period, hypoxia increased the mean skin temperature and mean heat transfer coefficient, as well as FBF and forearm vascular conductance. The increased blood flow in the cutaneous circulation during the hypoxic exposure may reflect cutaneous vasodilation and vasoconstriction in other regions of the body, since there was no alteration in CO and total peripheral resistance. During heat exposure, Tes rose faster at high altitude than at sea level. However, at the end of the 60-min heat exposure, all thermal as well as circulatory parameters showed no difference between the two altitudes, except for the FiBF. An attenuated vasodilation in the fingers during heat exposure at high altitude suggests differential vascular controls and possible impairment of thermoregulation when additional stress, such as heat, is imposed. The data suggest that cutaneous blood flow during heat exposure is not uniform throughout the entire skin in a hypoxic environment.

Adult↗
PubMed1986

Esophageal and tympanic temperature responses to core blood temperature changes during hyperthermia.

Esophageal, rectal, tympanic, and central blood temperature, i.e., pulmonary artery and aortic arch, were recorded in three patients during iatrogenic whole-body hyperthermia for the treatment of advanced malignant metastatic cancer. Aortic temperature closely followed changes in pulmonary arterial temperature, with an average delay time of 27 s. Esophageal temperature reflected quantitatively and more quickly (avg lag time, 80 s) the temperature changes in the pulmonary artery than tympanic membrane temperature. Tympanic temperature was consistently lower than the blood temperature of the heart during steady state. Therefore it is suggested that esophageal temperature is a preferable index of central blood temperature. Additionally, measurement of esophageal temperature can be made more easily and safely than tympanic membrane temperature.

Adult↗
PubMed1986

Energetics of wet-suit diving in Japanese male breath-hold divers.

The present study was undertaken to investigate energy balance in professional male breath-hold divers in Tsushima Island, Japan. In 4 divers, rectal (Tre) and mean skin (Tsk) temperatures and rate of O2 consumption (VO2) were measured during diving work in summer (27 degrees C water) and winter (14 degrees C water). Thermal insulation and energy costs of diving work were estimated. In summer, comparisons were made of subjects clad either in wet suits (protected) or in swimming trunks (unprotected), and in winter, they wore wet suits. The average Tre in unprotected divers decreased to 36.4 +/- 0.2 degrees C at the end of 1-h diving work, but in protected divers it decreased to 37.2 +/- 0.3 degrees C in 2 h in summer and to 36.9 +/- 0.1 degree C in 1.5 h in winter. The average Tsk of unprotected divers decreased to 28.0 +/- 0.6 degrees C in summer and that of protected divers decreased to 32.9 +/- 0.5 degrees C in summer and 28.0 +/- 0.3 degrees C in winter. Average VO2 increased 190% (from 370 ml/min before diving to 1,070 ml/min) in unprotected divers in summer, but in protected divers it rose 120% (from 360 to 780 ml/min) in summer and 110% (from 330 to 690 ml/min) in winter. Overall thermal insulation (tissue and wet suit) calculated for protected divers was 0.065 +/- 0.006 degree C X kcal-1 X m-2 X h-1 in summer and 0.135 +/- 0.019 degree C X kcal-1 X m-2 X h-1 in winter.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1986

Cardiac output by impedance cardiography during head-out water immersion.

This study was undertaken to ascertain the suitability of impedance cardiography for qualifying cardiac output during water immersion where the electrodes were wet. The cardiac output was compared during wet and dry immersion with the head above water by breath holding briefly at 3 lung volumes. For dry immersion, the subjects were protected from contacting water during immersion by enveloping the whole body in a thin plastic bag. For wet immersion, the subject went into the water wearing only trunks. Eleven healthy males served as subjects. Both basal thoracic impedance and the minimum rate of impedance change decreased during wet immersion. These changes were specific, which insignificantly influenced the computation of stroke volume as compared to dry immersion. Our results showed no statistical differences between wet and dry immersions, and between measurements made at total lung capacity functional residual capacity, or residual volume. It is concluded that impedance cardiography is applicable directly in wet conditions without having to protect the subject from getting wet.

Adult↗
PubMed1985

Hyperbaric diuresis and nocturia--a review.

Human divers are now able to engage in a multi-day dive to a considerable depth using the mixed gas saturation diving technique, however their daily activities are somewhat limited in the depth. One of the major problems that has not been generally appreciated is the potential for body fluid disturbances at high pressure due to the development of a sustained diuresis. In addition, a marked nocturia has been observed in recent saturation dives at 26-31 atmospheres absolute (ATA), which disturbs divers' sleep during the night. In this review, we will briefly discuss the basic characteristics and mechanisms of these disturbances of renal functions observed during hyperbaric exposure.

Adult↗
PubMed1985

Diving pattern of Tsushima male breath-hold divers (Katsugi).

The present study was undertaken to investigate the diving pattern, buoyancy-mass relationship, and some respiratory functions in professional male breath-hold divers in Tsushima Island, Japan. These divers always wear neoprene wet suits and use fins and 4-kg counterweights. They usually dive to 3-10 m depths. The rate of descent was 1.12 m/s for deeper dives (greater than 10 m), which is nearly twofold greater than that of Korean female divers also wearing wet suits and fins. However, the rate of ascent (0.8 m/s) was comparable to that of Korean women divers. On a typical summer day, they spend nearly 4 h in the water and perform 175 dives. The average dive and surface time were 39 and 42 s, respectively. The total bottom time was estimated to be 67 min/d, nearly twice that of Korean women divers. These divers do not adjust the counterweight and all are using a 4-kg weight. Nevertheless, the buoyancy-mass relationship revealed that they maintain the same degree of positive buoyancy (approximately 10% above the neutral level) at surface as do Korean women divers who adjust counterweights. The vital capacity was significantly greater in the diver than in the control (P less than 0.05), which was largely due to the greater expiratory reserve volume in the diver. The end-tidal O2 and CO2 pressures of the diver resting in air were not different from those of the control. These results indicate that, while the basic diving pattern is similar in both male and female breath-hold divers, the overall efficiency of diving (in terms of the rate of descent and the bottom time) appears to be superior in male divers.

Adult↗
PubMed1984

The immunosuppressive mode of action of mizoribine.

Mizoribine (MIZ) suppressed the mitogen response and mixed lymphocyte reaction (MLR) significantly at doses of 100 micrograms/ml and 10 micrograms/ml in a dose-response analysis. The 50% inhibition dose (ID50) was between 10 micrograms/ml and 1.0 microgram/ml, both in the mitogen response and MLR. In a kinetic study of the MLR, the degree of suppression with MIZ at a given dosage was essentially the same as the degree of suppression observed in the dose-response analysis when MIZ was added to MLR cultures from day 0 to day 4. In addition, MLR was more susceptible to the suppressive activity of MIZ at 100 micrograms/ml when MIZ was added near the peak of lymphocyte proliferation. This experiment also showed that MLR suppression induced by MIZ at 10 micrograms/ml was reversible and MLR activity had completely recovered 6-8 hr after its removal. MIZ had no inhibitory action on MLR-derived cytotoxic cells or the effector phase of cell mediated lymphocytotoxicity. These results clearly demonstrate that MIZ suppresses lymphoproliferation, but has no effect on the recognition phase or effector phase of cytotoxic lymphocytes.

Dose-Response Relationship, Immunologic↗
PubMed1984

Spontaneous maturation in the metastatic region of a bilateral testicular germ cell tumor.

A case of bilateral testicular germ cell tumor of different cell types was found to have a mature teratoma in the metastatic region. Histology of the right testis revealed seminoma and embryonal carcinoma while the left testis revealed seminoma and mature teratoma. A mature teratoma, containing cartilage components, was also found in the right para-aortic lymph node. The findings of the case are described and the literature on cases with maturation in the metastatic region are reviewed.

Adult↗
PubMed1984

[A case of advanced seminomatous germ cell tumor cured with PVB combination chemotherapy].

A case of stage IIB seminomatous tumor treated with the combination chemotherapy regimen of cis-platinum, vinblastin and bleomycin is presented. The patient was a 42-year-old man who was admitted to our hospital with the chief complaint of the right intrascrotal mass and edema in right lower extremity. Right radical orchiectomy was immediately performed under the diagnosis of testicular tumor. Histological diagnosis was pure seminoma. Paraaortic bulky metastasis and right hydronephrosis were found in the abdominal CT-scan. PVB therapy for initial treatment was started. After four courses of this therapy, retroperitoneal lymphadenectomy was performed. Because no live tumor cells were found histologically in any of the dissected material, complete response was considered to have been achieved by PVB therapy. Considering the poor survival and high relapse rate of advanced seminomatous tumor treated with radiotherapy, this PVB therapy should be the initial treatment for this disease.

Adult↗
PubMed1984

[Clinical evaluation of ceftizoxime in the treatment of complicated urinary tract infections].

Ceftizoxime (CZX) was given clinically to 80 patients with urogenital tract infections, in which 34 cases of complicated UTI satisfied the criteria of the UTI committee. CZX was administered for at least five days at a daily dose of 1 to 4 g in two divided doses by intravenous drip infusion. The overall clinical efficacy of CZX in 34 cases of complicated UTI was 59%, estimated by the criteria of the UTI committee. The overall clinical efficacy rate according to group of infection was: 64% for the 11 patients in the 1st group, 56% for the 9 patients in the 2nd group, 100% for the 5 patients in the 3rd group, 50% for the 4 patients in the 4th group and 20% for the 5 patients in the 5th group. No serious side effects were observed in the clinical or laboratory findings except for slight elevation in GOT & GPT values in two cases (2.5%), which returned to normal after CZX treatment. It is therefore suggested that CZX is a clinically useful and safe drug in the treatment of complicated UTI.

Adolescent↗
PubMed1984

[Chemotherapy after prostatectomy--effects of long term administration of Pivmecillinam (PMPC)].

The therapeutic efficacy of Pivmecillinam (PMPC) against urinary tract infections after prostatectomy was investigated. PMPC was orally administered at the dose of 300 mg/day for 2-14 weeks after initial intravenous postoperative chemotherapy with other antibiotics for 0-24 days (average 5.7 days). Thirty patients underwent retropubic prostatectomy and the other 59 patients received TUR-P. The chemotherapeutic efficacy for 19 patients who had over 10(3) CFU/ml of microorganisms was as follows: The effective rate was 48.4% after 2 weeks, 53.8% after 4 weeks, 66.7% after 5-6 weeks and 100% after 7-9 weeks. The prophylactic efficacy for 70 patients who had no or less than 10(3) CFU/ml of microorganisms was 64.3% after 2 weeks, 79.6% after 4 weeks, 86.7% after 5-6 weeks and 90.0% after 7-9 weeks. The overall clinical efficacy of PMPC for 89 patients was 60.7% after 2 weeks, 74.2% after 4 weeks, 83.3% after 5-6 weeks, 90.0% after 7-9 weeks and 100% after 10-14 weeks. No severe side effects were found in these 89 cases. In conclusion, PMPC is a useful drug for the long term treatment after prostatectomy.

Administration, Oral↗