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Biomedical subjects

Y Sawada

Publications and source records attributed to Y Sawada.

At least 307 records · Page 17Linked to original sources
PubMed1994

Coronary artery ectasia with annuloaortic ectasia.

A 50-year-old Japanese woman with annuloaortic ectasia was found to have total coronary artery ectasia without evident atherosclerosis. The coronary ectasia may have been secondary to or of similar etiology to the annuloaortic ectasia. There was neither stigmata of Marfan's syndrome nor any sign of dissection of the ascending aorta or coronary arteries. Furthermore, the patient was not elderly, and had no hyperlipidemia, diabetes mellitus, or history of smoking. There was a marked blood pressure difference between the arms, and linear calcification was present in the aortic wall. A stenotic lesion was present in the right mid-subclavian artery. Although it is impossible to rule out atherosclerosis as the etiology of these findings, the possibility that they may be a manifestation of Takayasu's arteritis is discussed.

Angiography↗
PubMed1994

[A hemodynamic comparison of cardiovascular stress responses during mental arithmetic and reaction time tasks].

The primary purpose of this study was to examine the covariation between preload (PL) and other cardiovascular stress responses during mental arithmetic (MA) and reaction time (RT) tasks. PL, stroke volume (SV), cardiac output (CO) and pre-ejection period (PEP) were obtained using impedance cardiography. Mean blood pressure (MBP) was measured by the vascular unloading method. Thirty-one male college students were given both MA and RT tasks with a counterbalanced order. Results indicated significant differences in heart rate reactivity which seems to provide evidence for a stronger vagal withdrawal in MA. Changes in CO and MBP were identical in these two tasks which might have resulted from a compensatory change in PL and SV. Specificity of PEP for the increased beta-adrenergic activity was supported by the correlation pattern among PL, MBP and PEP. The results were discussed in the context of cardiovascular regulating mechanisms.

Adolescent↗
PubMed1994

[Cardiac vagal withdrawal during stressful tasks estimated by the baroreflex sensitivity and respiratory sinus arrhythmia].

The primary purpose of this study was to compare the changes in baroreflex sensitivity (BRS) with those in respiratory sinus arrhythmia (RSA) during mental arithmetic (MA) and reaction time (RT) tasks. BRS was assessed by the sequence scanning method (Bertinieri et al., 1988) combined with the vascular unloading technique that enables beat-by-beat measurement in systolic blood pressure. Twenty-eight male college students were given both MA and RT tasks with the order counterbalanced. Results indicated significant differences in BRS and RSA reactivity that seems to be evidence for a stronger vagal withdrawal in MA. Reactivity in RSA was correlated more closely with respiratory variables (respiration rate, tidal volume, and end-tidal CO2) than in BRS. These findings suggest that BRS is more suitable for estimating cardiac parasympathetic control because of its greater independence from respiratory activity. The results were discussed concerning the patterning of cardiorespiratory stress responses.

Adolescent↗
PubMed1994

[Prostate specific antigen in patients with prostatic cancer--clinical usefulness of its measurement with sensitive enzyme immunoassay, TOSOH II PA assay].

The TOSOH II PA (AIA-PACK PA in the U.S.A.) monoclonal immunoenzyme assay was used and the clinical usefulness of prostate specific antigen (PSA) was evaluated in 39 men with prostatic cancer and 32 men with benign prostatic hyperplasia (BPH) confirmed pathologically. We evaluated the lower limit of detection in this assay by the mean PSA level plue 3 standard deviations in 5 separate experiments with a zero control sera as well as the mean PSA level minus 3 standard deviations in 5 separate experiments with serial dilutions of a known concentration of PSA. PSA concentrations of 0 to 0.25 ng/ml could not be distinguished from the zero control. Therefore, we set the lower limit of detection for the assay as 0.25 ng/ml. At our laboratory, the normal standard value was determined by the mean PSA level plus 3 standard deviations in 79 healthy men as 2.3 ng/ml. Of patients that underwent radical cystoprostatectomy for bladder cancer, all had PSA levels less than 0.25 ng/ml, while only 6% had PAP levels less than 0.11 ng/ml, the lower limit of detection in the TOSOH II PAP assay. We compared TOSOH II PA with Markit PA, a commonly used assay in Japan. Although there was a close linear correlation (r = 0.90) between the TOSOH II PA and Markit PA, the difference of slope in the linear regression lines was great, it was thought due to anti-PSA antibodies in each assay recognizing different epitopes of PSA in the blood.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Two cases of aorto-coronary bypass grafting for two different types of single coronary artery].

Single coronary artery is a rare congenital anomaly and its prognosis is good. This entity can be diagnosed only by coronary angiography in lift. Atherosclerotic obstruction of a single coronary artery causes a high incidence of sudden death, so this anomaly does not take a good course. We present two cases of CABG which have two different types of single coronary artery with some significant stenoses of the coronary arteries.

Aged↗
PubMed1994

Release of nitric oxide in response to acetylcholine is unaltered in spontaneously hypertensive rats.

OBJECTIVE: Although a decreased responsiveness to acetylcholine, an endothelium-dependent vasodilator, has been reported in arteries isolated from spontaneously hypertensive rats (SHR), the precise role of nitric oxide (NO) in the in vivo regulation of blood pressure is not clear. We investigated the effects of acetylcholine and of NG-nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor, on mean arterial pressure and the production of NO metabolites (nitrate and nitrite) in SHR and in Wistar-Kyoto (WKY) rats, their normotensive control strain. DESIGN: We determined serum levels of nitrate and nitrite before and after the intravenous injection of 40 micrograms/kg acetylcholine following the administration of L-NAME (30 mg/kg) or its vehicle in adult SHR and WKY rats. RESULTS: Acetylcholine administration significantly reduced mean arterial pressure in both SHR and WKY rats, accompanied by a significant rise in serum nitrate and nitrite. Administration of L-NAME significantly increased the mean arterial pressure in SHR and in WKY rats. L-NAME inhibited the hypotension induced by acetylcholine and the rise in serum nitrate and nitrite both in SHR and in WKY rats. CONCLUSION: The release of NO stimulated by acetylcholine was unaltered in SHR, supporting previous in vitro results.

Acetylcholine↗
PubMed1994

[The causes and timing of reoperation for coronary artery disease].

In eight hundred and sixteen consecutive patients undergoing coronary artery bypass grafting (CABG) within the past 19 years (1974 to 1993), repeated CABG were performed on 12 patients (1.47%). The main reasons for repeated CABG were graft failure (GF), progression of native disease (NP) and incomplete revascularization (IR). The incidence of GF only and GF combined NP were high either within a half year or around 5 years after CABG. When the recurrence of angina is noted after CABG, the catheter intervention should be chosen at first but the reoperation should be done not so late. Although all patients survived from reoperation, three patients continued to have mild angina pectories. If a reoperation is inevitable, maximum utilization of arterial graft and accomplishment of complete revascularization are emphasized.

Aged↗
PubMed1994

[Reoperation for mitral valve disease].

From 1978 to March 1994, 95 patients underwent repeated open heart surgery for mitral valve diseases. There were 48 men and 47 women. The mean age was 50 and the mean interval between initial and second operation was 8 years. The initial operations were OMC in 39, MAP in 13, OMC+MAP in 11, MVR in 30 and AVR in 2 patients. The hospital death occurred in 31 cases (32.6%). In recent cases, however the hospital death were reduced to 4 (14.8%). This was attributed to the change in myocardial protection from previous intermittent antegrade crystalloid to recent continuous combined antegrade and retrograde cardioplegia.

Adolescent↗
PubMed1994

[Effective chemoembolization for liver metastasis in a case of testicular cancer].

A 21-year-old male with a previous history of retroperitoneal tumor treated with chemotherapy, radiotherapy, immunotherapy and probe laparotomy was admitted with a complaint of right scrotal enlargement and liver tumor. He had retroperitoneal mass and large liver tumor on an abdominal CT scan. Right inguinal orchiectomy was performed on April 14, 1988. Histopathological diagnosis confirmed embryonal cell carcinoma plus seminoma. Cisplatin, vinblastine and bleomycin combination chemotherapy (PEB) was started and repeated for 4 courses. Repeat CT scan showed significant shrinkage of retroperitoneal and liver tumor, but not complete eradication of tumors. Chemoembolization of liver tumor was done on August 5, 1988. Biopsy of liver tumor revealed disappearance of viable tumor cells. On CT scan, no retroperitoneal tumor was detected on February 27, 1990, and no liver tumor was delineated on August 30, 1991. The patient was alive with no evidence of disease on February 28, 1994.

Adult↗
PubMed1994

[Surgical treatment of infective endocarditis].

Since 1976, 37 patients have undergone valve replacement for infective endocarditis at our institute. Twenty patients required surgery during the active stage and 17 in the inactive stage. The former group consisted of 17 native and three prosthetic valve endocarditis, and all patients in the latter group had native valve endocarditis. Eighteen patients had AVRs, 15 had MVRs and four had DVRs. Congestive heart failure was the indication for surgery in 80% of the active and 100% of the inactive group. There were nine early deaths (45%) and one late death in the active group, and one early (6%) and one late death in the inactive group. Operative mortality in the active group, however, has recently been reduced to 30% for the 10 patients operated upon in the past two years. Two patients with active endocarditis were complicated by rupture of cerebral mycotic aneurysms postoperatively and resulted in one early and one late death, respectively. It is suggested that timely surgical intervention according to the hemodynamic state of the patients is essential in reducing early mortality in infective endocarditis. Attention should be paid to cerebral mycotic aneurysm as one of the problems affecting on postoperative mortality and morbidity.

Adult↗
PubMed1993

Pharmacokinetic profiles of glycyrrhizin in patients with chronic hepatitis.

The pharmacokinetics of glycyrrhizin (G) in eight patients with chronic hepatitis receiving chronically i.v. administration of 120 mg dose of G was investigated. The plasma concentration of G in the patients after dosing declined in a monophasic manner. However, the pharmacokinetic profiles varied among patients. The mean elimination half-life (t1/2) and the total body clearance (CLtot) were 6.0 h (range 4.3-10.7 h) and 7.9 ml h-1 kg-1 (4.5-12.7 ml h-1 kg-1), respectively. The variation of the CLtot for G was closely related to that of aspartate aminotransferase (r = -0.739, p < 0.05) and alanine aminotransferase (r = -0.783, p < 0.05) activities in the plasma.

Adult↗
PubMed1993

Kinetic analysis of glycyrrhetic acid, an active metabolite of glycyrrhizin, in rats: role of enterohepatic circulation.

The role of enterohepatic circulation of glycyrrhetic acid (GA) in rats was determined by kinetic analysis of GA. The concentrations of GA in the plasma of the control rat (without bile duct cannulation) during the first 5 h after intravenous (iv) administration of GA (2, 5, 10, and 20 mg/kg) were similar to those in the bile duct-cannulated rat at each dose. No significant difference was observed in the values of the terminal half-life, the total body clearance, the distribution volume at steady state, the area under the curve of concentration in plasma versus time, and the mean residence time in each dose between both groups. When GA (2, 5, 10, and 20 mg/kg) was administered i.v. to the bile duct-cannulated rat, excretion of unchanged GA in bile was < 1% of each dose, that of the acid-hydrolyzed products was 14-16%, and that of GA-3-O-glucuronide was only 1-2%. In the control rat, a secondary peak of GA concentration was observed 12 h after i.v. administration of GA (20 mg/kg). The enterohepatic circulation of GA was confirmed by the linked-rat method in which bile of the donor rat after i.v. administration of GA (20 mg/kg) was allowed to flow directly into the duodenum of the recipient rat. GA was found in the plasma of the recipient rat after 6 h, and its concentration reached the maximum (approximately 0.5 microgram/mL) 8-12 h after dosing the donor rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Minimum tissue size required for hydra regeneration.

Small tissue pieces were excised from wild-type polyps of Hydra magnipapillata, allowed to regenerate, and the size-dependent characteristics of head regeneration were examined. The excised tissue piece was initially a square flat sheet. This piece gradually rounded up and, within 24 hr after excision, turned into a "spherical shell" which had a continuous ectodermal layer outside, a continuous endodermal layer inside, and an empty cavity at the center. The smallest spherical shell that could be produced had a diameter of 0.2 mm and contained 270-300 epithelial cells. A tissue piece too small to form a spherical shell always disintegrated, presumably due to lack of an osmotic barrier between the tissue and the environment. Of the spherical shells with a diameter of 0.2 mm, about half (47%) regenerated a head in about 5.5 days, while the rest remained as spherical shells or disintegrated. With an increase in diameter, the regeneration percentage increased, and regeneration time decreased. Similar size-dependent characteristics were also observed in a computer simulation study of regeneration based on the reaction-diffusion mechanism (Gierer and Meinhardt, Kybernetik 12, 30-39, 1972). These observations are consistent with the view that two independent factors are involved in determining the minimum tissue size for regeneration. One is the amount of tissue required to form a spherical shell. A tissue piece too small to form a spherical shell cannot survive and, hence, cannot regenerate. The other may be the reaction-diffusion mechanism. A pattern might not be formed below a critical limit size set by this mechanism.

Animals↗
PubMed1993

Nonlinear kinetics of threo-methylphenidate enantiomers in a patient with narcolepsy and in healthy volunteers.

We have studied the pharmacokinetics of methylphenidate enantiomers after the oral administration of different doses of racemic methylphenidate to one patient with narcolepsy and to four healthy volunteers. The plasma concentrations of (+)-methylphenidate were much higher than those of (-)-methylphenidate after each dose in all subjects. In the patient the oral clearance (CL/f) of (+)-methylphenidate fell 3-fold and the area under the concentration-time curve (AUC) rose 7-fold when the dose was increased from 20 to 40 mg (from 0.27 to 0.53 mg.kg-1), in spite of the relatively constant terminal half-life of 2.6-2.7 h. Similar dose-dependency was also observed in the healthy volunteers in the dose range of 10-60 mg (0.12-0.77 mg.kg-1). The mean value of CL/f for the 40 mg dose was significantly lower than that for the 20 mg dose. The mean AUC of the (+)-isomer corrected to a dose of 10 mg increased significantly between the 20 mg and 40 mg doses. In the urine (+)- and (-)-ritalinic acid were excreted for 48 h after each dose as 32-37% and 34-40% of the dose respectively. The mean total recoveries (sum of enantiomers of methylphenidate and its metabolite, ritalinic acid) in the urine were relatively constant (63-78% of the doses), suggesting that the changes in AUC with dose may not be due to a change in the intestinal absorption of racemic methylphenidate. We conclude that the nonlinear kinetics of (+)-methylphenidate may be due to saturation of its presystemic elimination.

Administration, Oral↗