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Biomedical subjects

S Sagawa

Publications and source records attributed to S Sagawa.

At least 37 records · Page 2Linked to original sources
PubMed1996

Orientation of glutaraldehyde-fixed erythrocytes in strong static magnetic fields.

In a uniform static magnetic field up to 8 Telsa, glutaraldehyde-fixed erythrocytes showed an orientation in which their disk plane was perpendicular to the magnetic field. The paramagnetism of membrane-bound hemoglobin was through to contribute significantly to this orientation. The observation of magnetic orientation is directed toward understanding the fundamental microstructural aspects of the erythrocyte.

Cell Polarity↗
PubMed1996

[Tumor enucleation for intrapelvic schwannoma: a report of two cases].

A 65-year-old man and a 35-year-old woman were diagnosed with intrapelvic tumors originating from the sacral nerves by computed tomographic (CT) scan, magnetic resonance imaging (MRI) and angiography. These tumors were tightly adhered to the iliac arteries and veins and could not be resected completely. Since the cryostat sections revealed benign schwannomas histopathologically, we enucleated the tumors without the pseudocapsules. All of the 57 intrapelvic schwannomas previously reported in Japan were resected with pseudocapsules. Both of our patients showed improvement of subjective symptoms, but should be followed up and examined for the presence of regrowth of tumors.

Adult↗
PubMed1996

[The effect of a water-cooled vest on heat intolerance in a patient with anhidrosis due to familial amyloidosis of Finnish type].

The patient was a 70-year-old male with familial amyloidosis of Finnish type who complained of heat intolerance due to anhidrosis during outdoor activities in summer. A water-cooled TM-2 vest was tried for this patient to reduce his body heat during exercises. Following the morning activities including jogging in August his body temperature rose up to 38.0 degrees C without wearing the partly frozen vest. However, when he wore it, his temperature rose up to only 37.2 degrees C after the exercises, which was 0.8 degree C lower than when he did not wear the vest. Headache and tachycardia during and following the morning activities did not appear by wearing the vest. In the heat loading test, in which the room temperature was raised from 28.0 degrees C to 38.0 degrees C for 15 minutes and kept at 38.0 degrees C for 60 minutes with 60% humidity, the rises of his skin and esophageal temperatures with wearing the partly frozen vest for the last 60 minutes were 1.2 degrees C and 0.4 degree C lower, respectively, than his skin and esophageal temperatures without wearing it. Concomitantly, the increase of heart rate was suppressed in the same test condition. Wet vest in running water showed the similar effects. Therefore, we concluded that the use of water-cooled TM-2 vest was effective in alleviating the symptoms and signs of his heat intolerance.

Aged↗
PubMed1995

Mechanism of thirst attenuation during head-out water immersion in men.

The purpose was to determine whether extracellular volume or osmolality was the major contributing factor for reduction of thirst in air and head-out water immersion in hypohydrated subjects. Eight males (19-25 yr) were subjected to thermoneutral immersion and thermoneutral air under two hydration conditions without further drinking: euhydration in water (Eu-H2O) and euhydration in air, and hypohydration in water (Hypo-H2O) and hypohydration in air (3.7% wt loss after exercise in heat). The increased thirst sensation with Hypo-H2O decreased (P < 0.05) within 10 min of immersion and continued thereafter. Mean plasma osmolality (288 +/- 1 mosmol/kgH2O) and sodium (140 +/- 1 meq/l) remained elevated, and plasma volume increased by 4.2 +/- 1.0% (P < 0.05) throughout Hypo-H2O. A sustained increase (P < 0.05) in stroke volume accompanied the prompt and sustained decrease in plasma renin activity and sustained increase (P < 0.05) in plasma atrial natriuretic peptide during Eu-H2O and Hypo-H2O. Plasma vasopressin decreased from 5.3 +/- 0.7 to 2.9 +/- 0.5 pg/ml (P < 0.05) during Hypo-H2O but was unchanged in Eu-H2O. These findings suggest a sustained stimulation of the atrial baroreceptors and reduction of a dipsogenic stimulus without major alterations of extracellular osmolality in Hypo-H2O. Thus it appears that vascular volume-induced stimuli of cardiopulmonary baroreceptors play a more important role than extracellular osmolality in reducing thirst sensations during immersion in hypohydrated subjects.

Adult↗
PubMed1995

Responses of the circulatory system and muscle sympathetic nerve activity to head-down tilt in humans.

These experiments were conducted to examine whether changes in central and peripheral hemodynamics were proportional to muscle sympathetic nerve activity (MSNA) during graded head-down tilt (HDT). Twelve healthy males (19-42 yr old) underwent HDT at 15 degrees and 30 degrees for 10 min each with a 10-min rest period between the trials. MSNA at 15 degrees HDT declined by 31 +/- 5% (P < 0.05) for burst rate and by 37 +/- 3% (P < 0.05) for total activity. At 30 degrees HDT, the reduction in MSNA was 51 +/- 5% for burst rate (P < 0.05 vs. 15 degrees HDT) and 46 +/- 5% for total activity (P < 0.05 vs. 15 degrees HDT). Stroke volume increased (P < 0.05) during both 15 degrees and 30 degrees HDT, but heart rate and blood pressure remained unchanged. A concurrent increase in central venous pressure (P < 0.05) and stroke volume with a reduction of thoracic impedance (P < 0.05) suggests that both pressure and volume in the atrium were elevated during HDT, and the magnitude of these changes was greater (P < 0.05) at 30 degrees HDT than at 15 degrees HDT. Forearm blood flow increased during HDT at both 15 degrees and 30 degrees, and the magnitude of the increase was greater (P < 0.05) at 30 degrees HDT. It is concluded that the magnitude of the loading of the cardiopulmonary mechanoreceptors during HDT was higher at 30 degrees in comparison to 15 degrees. This increased the afferent firing rate by the cardiopulmonary receptors and probably inhibited sympathetic outflow in the central nervous system.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Changes in muscle sympathetic nerve activity and renal function during positive-pressure breathing in humans.

The possibility that the decreased urinary flow during continuous positive-pressure breathing (CPPB) may be a consequence of a reflex mediated via the cardiopulmonary baroreceptors to increase neurohumoral secretion or to change the sympathetic outflow was assessed. Muscle sympathetic nerve activity (MSNA) on the right peroneal nerve, vasoactive hormones, and renal and cardiovascular responses were measured during CPPB (+12 mmHg) in 10 male subjects (22.0 +/- 0.6 yr, 66.8 +/- 1.5 kg body wt). The experiments consisted of a 1-h control, 1 h with CPPB (experimental) or without CPPB (a time control), and a 1-h recovery period. Two blood samples were taken during each period for measurements of arginine vasopressin (AVP), plasma aldosterone (PAldo), plasma renin activity (PRA), norepinephrine, and atrial natriuretic peptide (ANP), and urine was collected hourly for the measurement of urine volume and electrolytes and clearances. MSNA rapidly increased (P < 0.05) at the onset of CPPB, continued to increase during exposure, and rapidly returned to the normal level at recovery. The MSNA changes coincided with increased plasma NE and were concurrent with a reduced (P < 0.05) urine output associated with a reduction of both free water and osmolal clearances, Na+ and osmolal excretions, and creatinine clearance (glomerular filtration rate). AVP and PRA increased (P < 0.05), whereas PAldo and ANP were unchanged. The results are consistent with the concept that increased sympathetic outflow may play a role in the reduction of urinary output and Na+ excretion during unloading of the cardiopulmonary receptors.

Adult↗
PubMed1994

Effect of water temperature on diuresis-natriuresis: AVP, ANP, and urodilatin during immersion in men.

Effects of water temperature on diuresis, natriuresis, and associated endocrine responses during head-out immersion were studied in eight men (23.4 +/- 0.3 yr) during four 5-h experimental conditions: air control at 28 degrees C and immersion at 34.5 degrees C [thermoneutral (Tnt)], 36 degrees C [above Tnt (aTnt)], and 32 degrees C [below Tnt (bTnt)]. Esophageal temperature decreased by approximately 0.4 degrees C in bTnt and increased by approximately 0.5 degrees C in aTnt. Cardiac output increased by approximately 80% in aTnt and approximately 40% in bTnt while thoracic impedance, an index of central blood pooling, decreased by 7.5 omega in bTnt (NS vs. Tnt) and 8.8 omega in aTnt (P < 0.05 vs. Tnt and bTnt). Total peripheral resistance decreased at all temperatures (50% in aTnt, 20% in bTnt). Urine flow and Na+ excretion increased by sixfold in bTnt and Tnt but by only threefold in aTnt. Creatinine clearance was unchanged while osmolal clearance (but not free water clearance) increased two-fold with all immersions. Plasma atrial natriuretic peptide (ANP), urinary urodilatin, and urinary guanosine 3',5'-cyclic monophosphate increased while plasma renin activity, aldosterone, and arginine vasopressin (AVP) decreased similarly at all temperatures. bTnt did not potentiate diuresis by selective attenuation of AVP. The overall natriuretic response exhibited a higher correlation with urodilatin (r = 0.45, P < 0.001) than with ANP (r = 0.26, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Orientation of erythrocytes in a strong static magnetic field.

The frequency of exposure to strong magnetic fields has increased as the magnetic-resonance image-diagnostic technique (MRI) and passenger transport systems based on the principle of magnetic levitation have come into wider use. Accordingly, it has become necessary to more systematically assess their influence on the body and set strict guidelines on acceptable limits of magnetism exposure. Therefore, we have assessed the influence of an uniform static magnetic field (8 T in maximum) on normal erythrocytes. The erythrocytes were oriented with their disk plane parallel to the magnetic field direction. These erythrocytes were influenced even by 1 T and almost 100% of them were oriented when exposed to 4 T. Furthermore, the degree of orientation was not influenced by the state of hemoglobin (oxy: diamagnetic, deoxy and met: paramagnetic). The dependence of the measured degree of orientation on the intensity of the magnetic field was in good agreement with the theoretical equation for the magnetic orientation of diamagnetic substances. As a result of a numerical analysis based on the equation, the anisotropic diamagnetic susceptibility of erythrocytes was found to be delta chi = 8 x 10(-22) electromagnetic units/erythrocyte. It was almost in agreement with the calculated value delta chi = 6 x 10(-22) emu/erythrocyte estimated from the diamagnetism of the membrane constituents of erythrocyte.

Cell Polarity↗
PubMed1993

Cardiovascular responses to upright tilt at a simulated altitude of 3,700 m in men.

To examine the effects of high altitude on cardiovascular responses to orthostasis, 11 healthy males were tested at a 10-min passive 70 degrees head-up tilt at sea level and at a simulated high altitude of 3,700 m. During the control period in the supine position, heart rate and forearm blood flow were higher at high altitude (p < 0.05). Mean arterial pressure remained unchanged during head-up tilt at sea level, but it reduced from 82 mm Hg to 72 mm Hg (p < 0.05) during head-up tilt at high altitude. There were no altitude-related changes in the magnitude of the increase in forearm vascular resistance and the reduction in cardiac output and laser-Doppler skin blood flow in response to head-up tilt. The total peripheral resistance increased from 14.4 to 20.5 mm Hg.L-1 x min-1 (p < 0.05) during head-up tilt at sea level, but the change was not significant at high altitude. The lack of altitude-related changes in forearm vascular resistance and laser-Doppler skin blood flow during head-up tilt in the presence of attenuated total peripheral resistance response at high altitude may suggest that the orthostatic hypotension at high altitude is associated with a lower magnitude of vasoconstrictor response in the regions other than the limbs and the skin.

Adult↗
PubMed1992

Effect of dehydration on thirst and drinking during immersion in men.

The mechanism for reduced voluntary water intake during water immersion was studied in eight men (19-25 yr of age) immersed to the neck while sitting for 3 h at 34.5 degrees C or in air at 28 degrees C when euhydrated (Eu-H2O and Eu-air, respectively) and hypohydrated (Hypo-H2O and Hypo-air) by 3.6% body weight loss. Thirst sensations (degree of thirst, mouth dryness and taste, drinking desirability, and stomach fullness) were similar at the beginning of Hypo-air and Hypo-H2O test periods. Initial drinking of tap water (15 degrees C) was 216 +/- 30 ml/7 min (P less than 0.05) with Hypo-air, decreased to 108 +/- 28 ml/7 min (P less than 0.05) with Hypo-H2O, and was 10-50 ml/10-30 min thereafter. Intake was less than 10 ml/10-30 min in Eu-air, and there was no drinking in Eu-H2O. Within the first 10 min of immersion, compared with Hypo-air findings, the significant reduction in drinking in the Hypo-H2O experiment was associated with unchanged plasma Na+, plasma osmolality, heart rates, and mean arterial pressures; the different responses were increased cardiac output, plasma volume, and atrial natriuretic peptides and decreased plasma renin activity and arginine vasopressin. Thus the extracellular pathway, as opposed to the osmotic pathway, appears to be the major mechanism for immersion-induced suppression of drinking.

Adult↗
PubMed1992

Alpha-fetoprotein-producing adenocarcinoma of the ureter.

We report a case of primary ureteral tumor producing alpha-fetoprotein (AFP). Computerized tomography, ultrasonography and endoscopy of the bile duct revealed no obvious tumor in the liver, gallbladder, bile duct, pancreas or ovary. Total nephroureterectomy was performed, and histopathological examination revealed adenocarcinoma of the ureter lined with transitional cell carcinoma in its base. The tumor was stained with immunohistological AFP stain, and the high serum AFP level normalized after resection of the tumor.

Adenocarcinoma↗
PubMed1992

[Effect of HLA matching in renal transplantation].

Evaluation of HLA-matching is useful in determining graft function and survival in a recipient in cadaveric renal transplantation. The effects of HLA on graft function, which serum creatinine indicative of, and graft survival were examined in both living and cadaveric transplantation in 280 Japanese renal transplants performed at Osaka University and Osaka Prefectural Hospital between October, 1982 and December, 1991 (cadaver 68, living 212). HLA-DR mismatch had a strong effect in living transplants, whereas no disparity was found in cadaver transplants with HLA-DR mismatch. HLA-B, DR mismatch had more effect than HLA-DR in cadaver transplants, and the same effect as HLA-DR in living transplants. HLA-AB affected graft function. It can be used to predict the effect of long-term graft survival. The HLA-haplotype match had the strongest association with graft survival and function in both cases of living and cadaver transplants. HLA-haplotypes of a cadaveric donor and a recipient were presumed by means of the linkage disequilibrium. These findings showed that HLA-matching, especially of haplotype, is an essential factor in relatively low risk renal transplant survival and function. 1-haplotype-matched transplantation, determined by the family study or presumed by the linkage disequilibrium is recommended if not 2-haplotype matched.

Adult↗
PubMed1992

Cardiovascular responses to upright tilt in man during acute exposure to 3 atm abs air.

To examine the effect of acute hyperbaric exposure on cardiovascular response to orthostasis, a passive 70 degrees head-up tilt (HUT) test was performed for 15 min in a simulated compressed-air hyperbaric environment of 3 atm abs at ambient temperature of 31 degrees C (thermoneutral) on 8 male subjects. Heart rate (HR), blood pressure, cardiac output (CO) by impedance cardiography, forearm blood flow (FBF) by the occlusion plethysmography, and laser-Doppler skin blood flow (BFLD) on the thigh were measured for 15 min before, during, and after HUT. Esophageal temperature and HR data were recorded continuously. An identical test was performed in a 29 degrees C (thermoneutral) normal atmospheric condition. None of the subjects showed signs of syncope during HUT in either environment. Baseline HR was significantly lower (P less than 0.05) at 3 atm abs, and the increase in HR (delta HR) during HUT was of the same magnitude (15 beats/min) at both atmospheric pressures. The reduction of systolic blood pressure (delta SBP) was identical in both environments. Thus, the chronotropic response to HUT (delta HR/delta SBP) was the same. A marked reduction in CO (P less than 0.05) was attributed to a reduction of stroke volume during HUT, and the reduction was greater (P less than 0.05) at 3 atm abs. There were no pressure-dependent changes during HUT in FBF, forearm vascular resistance, and BFLD except for a greater increase (P less than 0.05) in total peripheral resistance at 3 atm abs. These observations suggest that orthostatic tolerance was maintained in the presence of lower CO at 3 atm abs, probably by a greater vasoconstrictor response in the splanchnic areas. We conclude that the substantial bradycardia which occurred at 3 atm abs did not interfere with a normal response to orthostasis in humans because of a peripheral vasoconstriction caused by the elevated oxygen pressure and an enhanced increase in total peripheral resistance which occurred during HUT in 3 atm abs.

Adult↗
PubMed1991

Sympathetic nerve activity and renal responses during continuous negative-pressure breathing in humans.

A stretch stimulus of the cardiopulmonary receptors results in a diuresis and natriuresis in dogs due to a suppression of renal sympathetic nerve activity. In the present experiment, the stretch stimulus in humans was given by means of continuous negative-pressure breathing (CNPB), and muscle sympathetic nerve activity (MSNA), renal responses, and hormones were measured to examine whether MSNA response during CNPB correlated with the usual renal and hormonal responses for stretch stimulus of the cardiopulmonary receptors. Nine healthy males were subjected to CNPB at -11 mmHg for 60 min. MSNA in the peroneal muscle nerve fascicles was measured continuously before (pre-CNPB), during, and after CNPB (post-CNPB). A step and sustained decrease (P less than 0.05) in MSNA (30 +/- 6% for burst frequency and 37 +/- 4% for total activity from pre-CNPB level) was observed during CNPB and it returned to pre-CNPB level at post-CNPB. Urinary excretion increased by 58 +/- 18% (P less than 0.05) during CNPB, and the diuresis was entirely osmolal in nature because of a significant increase (P less than 0.05) in Na excretion and a constant free-water clearance. The plasma level of norepinephrine decreased significantly (P less than 0.05) during CNPB and remained decreased (P less than 0.05) at post-CNPB. A twofold increase (P less than 0.05) in plasma atrial natriuretic peptide and a 35 +/- 9% reduction (P less than 0.05) in plasma renin activity were observed during CNPB, whereas no change was observed in plasma aldosterone and arginine vasopressin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Retroperitoneal cavernous hemangioma: a case report].

A 55-year-old man was shot at the age of 50. At that time CT revealed a mass near the spleen. Thereafter, CT did not reveal any growth of the mass, but to examine the mass in detail he was hospitalized to our department. The mass was diagnosed as left adrenal cavernous hemangioma, since, on aortography, it was typical cavernous hemangioma and fed mainly from the left inferior phrenic artery. The mass was resected with the spleen, thoracic wall, and part of diaphragma. At the operation the left adrenal gland was identified to be intact. Histopathological diagnosis was retroperitoneal cavernous hemangioma. This is the 19th case of retroperitoneal cavernous hemangioma in the Japanese literature.

Hemangioma, Cavernous↗
PubMed1991

[Leiomyosarcoma of the spermatic cord: a case report].

A 63-year-old man presented with painless hard swelling of left scrotal contents. Left orchiectomy with high ligation of the spermatic cord was done with clinical diagnosis of testicular tumor. Histopathologically, this tumor was diagnosed as leiomyosarcoma, primarily, arising from the spermatic cord. After operation, prophylactic radiotherapy (60Co, 5,890 rad) was given locally. There has been neither local recurrence nor metastasis for 10 months after operation. This is the 18th case of leiomyosarcoma of the spermatic cord in Japan.

Combined Modality Therapy↗