Search PubMed⌕ Search

Biomedical subjects

T Aoki

Publications and source records attributed to T Aoki.

At least 865 records · Page 48Linked to original sources
PubMed1990

Radionuclide assessment of left ventricular function during dobutamine infusion in patients with coronary artery disease: comparison with ergometer exercise.

The effects of dobutamine on left ventricular function were assessed employing radionuclide ventriculography (RNV) in 7 normal subjects (Group 1) and 21 patients with coronary artery disease (Group 2). After routine bicycle ergometer exercise RNV, dobutamine infusion was started at 5 micrograms/kg/min and the dosage was increased by 5 micrograms/kg/min every 4 minutes to a total of 15 micrograms/kg/min. In Group 1, left ventricular ejection fraction (LVEF) increased by both ergometer exercise and dobutamine infusion. In Group 2, LVEF did not increase during exercise, but increased during dobutamine infusion without evidence of significant myocardial ischemia. Only 2 patients in Group 2 had new regional wall motion abnormality. Left ventricular end-diastolic volume (LVEDV) in Group 2 increased from 191 +/- 19 to 210 +/- 18 ml during ergometer exercise, but decreased from 193 +/- 18 to 153 +/- 19 ml during dobutamine infusion. Short-term low-dose infusion of dobutamine may be used in patients without evidence of significant myocardial ischemia, but probably cannot be substituted for exercise testing in patients with mild to moderate coronary artery disease.

Coronary Disease↗
PubMed1990

Assessment of left ventricular function after sublingual administration of nifedipine in patients with moderate to severe hypertension.

To evaluate the left ventricular functional changes induced by acute decreases in blood pressure in 15 patients with systemic hypertension and left ventricular hypertrophy, this study used Doppler and M-mode echocardiographic derived left ventricular indices. After 30 minutes of administration of sublingual nifedipine, both systolic and diastolic blood pressure decreased and heart rates increased. The left ventricular end-systolic dimension decreased but not the end-diastolic dimension, which suggests that sublingual nifedipine may decrease only afterload, not preload. Total peripheral resistance decreased from 2770 to 1960 dyne.sec.cm-5. The M-mode-derived peak rate of dimension changes improved both the systolic and diastolic phase, and Doppler-derived indices of atrial contribution to ventricular filling decreased. Because both the systolic and diastolic phase indices of LV function are sensitive to variations in both preload and afterload, the improvement of myocardial contractility per se cannot necessarily be attributed to the direct effect of the drug to myocardium. Though favorable effects on the myocardial oxygen supply-demand ratio or increased adrenergic tone stimulated by the decline in systemic arterial pressures may contribute to the augmentation of LV systolic and diastolic function observed after nifedipine in the present study, the apparent augmentation of LV function appears to be attributable primarily to afterload reduction.

Administration, Sublingual↗
PubMed1990

A case of spontaneous mesenteric hematoma and a review of 17 cases in Japan.

A 47 year-old male was admitted to Miyazaki Medical college Hospital for further evaluation of an abdominal mass in the left upper quadrant. Abdominal ultrasound (US) and abdominal computed tomography (CT) showed two cystic masses in the mesenterium, which were suspected to be hematomas, but were not related to the pancreas, kidney or spleen. Superior mesenteric artery angiography and gallium (GA)-scintigraphy showed no definite findings. The patient underwent laparotomy on a suspicion of mesenteric hematoma. Two 4 x 3 x 3 cm soft tumors were found in the small intestinal mesenterium. These masses were histopathologically hematomas and surrounded by thick collagenous granulation tissue. The patient had no recent history of abdominal trauma, taking drugs capable of producing bleeding tendency, and/or vascular disease. The case was diagnosed as spontaneous mesenteric hematoma.

Hematoma↗
PubMed1990

Comparative studies on the usefulness of phosphate versus glycerin enema in preparation for colon examinations.

Fifty of 100 persons who had undergone health screening received phosphate enema while the other 50 received glycerin enema prior to proctoscopy and barium enema, and their usefulness for preparation for colon examination was compared by a double-blind test. There was no significant difference in the degree of colonic cleansing achieved by proctoscopy and barium enema. In the subjects who received phosphate enema, the incidence of abdominal pain was less than that in those who received glycerin enema, while the effect of phosphate enema on defecation appeared later than that of glycerin enema, indicating prolonged stool retention in the subjects given phosphate enema. To study the safety of the two enemas, either phosphate enema, glycerin enema or physiological saline solution as a control was administered at 0.35 ml/animal in the rectum by 4-h closure of the anus in 10 male 7-week-old Wistar rats, and the rectal mucosa was observed for irritation macroscopically and histopathologically. Glycerin enema produced less irritation than phosphate enema diffusely in the entire area of the rectum, while phosphate enema produced more local irritation at the end of the rectum than glycerin enema. The differences in the extent of irritation and injury between phosphate and glycerin enemas were considered to be derived from differences in the pharmacologic actions of these drugs. If the extent of injury were included in the extent of irritation, the difference in irritation between phosphate and glycerin enemas would not be significant. As described above, no specific difference seem to exist in the usefulness of phosphate and glycerin enemas as preparation for colon examination.

Animals↗
PubMed1990

Influence of age on left ventricular performance during exercise in normal Japanese subject: assessment by radionuclide ventriculography.

To assess the effects of age on left ventricular performance, multistage supine ergometer exercise radionuclide ventriculography (RNV) was performed in 92 normal subjects. The subjects ranged in age from 24 to 86 years and were free of cardiopulmonary disease and diabetes. Age-related changes in exercise duration, left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), cardiac output (CO) left ventricular ejection fraction (LVEF), left ventricular dv/dt, systolic and diastolic time indexes of dv/dt, and peak systolic pressure/left ventricular end-systolic volume (PSP/LVESV) were analyzed at rest and during the peak exercise stage. Age-related decrease in LVEDV and peak diastolic dv/dt were significant at rest. The time indexes of ECG R to peak systolic dv/dt and time of end-systole to peak diastolic dv/dt also were prolonged with age. Both maximum heart rate and exercise duration were shown to decline with age. No age-related difference was observed in LVESV, LVEF or PSP/LVESV either at rest or during exercise. However, the change of LVEF and LVESV during exercise was less in subjects aged 60 or more. These results indicate decreased left ventricular function during exercise in elderly subjects.

Adult↗
PubMed1990

The cardiovascular effects of atracurium and it's metabolite.

The administration of atracurium to humans has been reported to produce little cardiovascular effects in clinical doses. The cardiovascular effect, histamine-releasing and catecholamine releasing effects of intravenous injection of atracurium 0.6 and 1.2 mg.kg(-1) were studied in man, and also the cardiovascular and catecholamine releasing effects of laudanosine which is a metabolite of atracurium by Hofmann degeneration, were studied in dogs. The increase in human plasma concentration of histamine, hypotension and tachycardia were found with the dose of atracurium 1.2 mg.kg(-1). The intravenous administration of laudanosine 10 micro g.kg(-1) to dogs produced minimal epinephrine, norepinephrine releases and cardiovascular changes.

Journal Article↗
PubMed1990

Acute and subacute cytogenetic effects of the trihalomethanes on rat bone marrow cells in vivo.

The mutagenic effects of the trihalomethanes (THMs: chloroform, CHCl3; dichlorobromomethane, CHCl2Br; dibromochloromethane, CHClBr2; bromoform, CHBr3), found in chlorinated drinking water have been studied for their ability to induce chromosome aberrations (CA) in vivo in rat bone marrow cells. THMs were administered intraperitoneally (i.p. acute) and orally (subacute). Using a maximal dose of 1 mmole/kg body weight, positive results were noted for CHCl3, CHCl2Br, CHClBr2 and CHBr3 with i.p. treatment, and for CHCl3 and CHBr3 with oral treatment. The time-dependent increase in CA showed a maximum level at 12 h after i.p. injection and at 18 h after the fifth and last day of oral treatment.

Administration, Oral↗
PubMed1990

Modulatory interaction between initial clofibrate treatment and subsequent administration of 2-acetylaminofluorene or sodium phenobarbital on glutathione S-transferase positive lesion development.

The effects of 2-acetylaminofluorene (2-AFF) or sodium phenobarbital (PB) treatment subsequent to clofibrate (CF) administration in terms of preneoplastic lesion development and induction of hepatocellular carcinomas (HCC) were studied using Fischer 344 rats. Animals received CF (0.3% in diet) for the initial 30 weeks, and then either 2-AAF (0.01% in diet), PB (0.05% in diet) or basal diet until week 78. Further groups were initially given basal diet, and then treated with 2-AAF or PB week 30. Two-thirds partial hepatectomy was carried out on all animals at week 3, sacrifice of representative groups being performed at weeks 30, 48 and 78. No glutathione S-transferase placental form positive (GST-P+) or negative focal or nodular lesions were apparent at the cessation of CF administration. The induction of GST-P+ focal lesions by 2-AAF was markedly decreased at week 48 in the group previously given CF (P less than 0.05) and furthermore, the respective incidences of HCC at week 78 were 4/17 (23.5%) in the CF----2-AAF group and 7/17 (41.2%) in the 2-AAF alone case. No significant differences between CF----PB and PB alone groups were evident with regard to either GST-P+ lesions and HCC at weeks 48 and 78. No CF-specific GST-P negative neoplastic nodules or HCC were observed in any of the experimental groups. These results suggest that pretreatment with CF may inhibit the induction of GST-P+ focal lesions and HCC by subsequently administrated 2-AAF and that CF demonstrates no initiating activity for liver carcinogenesis under the present condition.

2-Acetylaminofluorene↗
PubMed1990

The influence of spacers on forces exerted on the abutment teeth of complete mandibular overdentures.

The avoidance of lateral forces on overdenture retainers is essential to prevent pathological change in the supporting tissues of the root abutment. In this study, the influence of spacer thickness on the vertical and lateral forces exerted on overdenture abutments was examined clinically. Two subjects with an edentulous maxilla, two canines and a left first premolar remaining in the mandible were selected for the experiment. The anchor type attachment was embedded in the left canine portion of the denture base. The transducer used for the previous study (Ogata et al., 1990), was embedded in this left canine portion. The transducer could detect the magnitude and direction of lateral forces exerted on an abutment tooth parallel to the Camper's plane. The other transducer was embedded in the left first mandibular premolar area, and could detect vertical forces exerted on the abutment tooth perpendicular to the Camper's plane. Furthermore, the transducer could change the space between a denture base and an abutment tooth to 1.5 mm, 0.6 mm or 0.3 mm. Therefore measurements could be made in the same way as if three experimental dentures had been used with a different thickness spacer. Recordings of forces were taken during food chewing, using each spacer on the day of denture insertion and twice at intervals of 1-2 weeks thereafter. The results demonstrated that as spacer thickness decreased, the magnitude of the lateral forces decreased, while the magnitude of the vertical forces increased. These findings suggest that a large part of the lateral component of forces exerted on an abutment tooth could be converted into a vertical component by using a thinner spacer.

Bite Force↗
PubMed1990

Occlusal force distribution in lower complete overdentures.

A space between the denture base and a root cap can effectively control the distribution ratio of occlusal force to abutment teeth and an alveolar ridge. The purpose of this study on abutments was to analyse the effect of variation in space (0 mm (no space), 0.3 mm and 0.6 mm) on the above ratio. Six subjects, 38-65 years of age, each with an edentulous maxilla and several teeth remaining in the mandible, were selected for this experiment. The lower experimental denture had embedded a transducer which could detect a change in the vertical force applied to the experimental tooth. This transducer was capable of changing the vertical space between a denture base and an experimental tooth. Each subject was asked to increase the occlusal force applied to the denture from zero to the maximum loading rate of 5 kgf s-1. The occlusal force and the force exerted on the experimental tooth were recorded in each space 1 month after insertion of new dentures. The following results were obtained: (i) when the occlusal force was applied to the artificial tooth just above the abutment tooth, the mean ratio in the 0 mm space was 60% of the force applied to the denture, the ratio in the 0.3 mm space was 50%, and the ratio in the 0.6 mm space was 30%; (ii) if the occlusal force was applied to the point 10 mm distant from the point just above the experimental tooth, the magnitude of the ratio was decreased by 60-80%.

Adult↗
PubMed1990

Activation of kallikrein-kinin system in human plasma with purified serine protease from Dermatophagoides farinae.

An aqueous extract from a mite culture, of Dermatophagoides farinae, activated prekallikrein to kallikrein in normal plasma. Crude protein preparation, obtained by ammonium sulfate precipitation (95% saturation) from the extract, exhibited high activity (0.81 units/mg protein) towards a synthetic substrate of coagulation factor XIIa, Boc-Gln-Gly-Arg-MCA, and had also activity to form kallikrein in human plasma deficient in coagulation factor XII. Treatment of the protein preparation with phenylmethylsulfonyl fluoride (PMSF), an inhibitor of serine enzyme, gave rise to inactivation of both activities. Thus, the serine protease specific for Boc-Gln-Gly-Arg-MCA in mite cultures of D. farinae was purified by ammonium sulfate precipitation and chromatographies on p-aminobenzamidine-sepharose CL-4B, DEAE-Toyopearl 650M, Sephadex G-75 superfine and Sephacryl S-200. The purified protease was homogeneous electrophoretically, and its molecular weight was estimated to be 30,000. The optimum pH and temperature were around 7.5 and 50 degrees C, respectively. The specific activity was 36 units/mg protein at pH 7.4 and 37 degrees C. The activity was completely inhibited by PMSF. The serine protease had the activity to activate the kallikrein-kinin system in normal human plasma.

Animals↗
PubMed1990

Dipyridamole radionuclide ventriculography in patients with coronary artery disease: comparison with ergometer exercise.

Intravenous administration of dipyridamole during radionuclide ventriculography (RNV) was performed in 26 consecutive patients with symptomatic coronary artery disease. The authors compared the results of dipyridamole-RNV with those of ergometer exercise-RNV in detecting myocardial ischemia. During exercise, ST depression, regional wall motion (RWM) abnormalities, and decreased left ventricular ejection fraction (LVEF) were observed in 21 (81%), 23 (88%), and 20 (77%) patients, respectively. However, after intravenous dipyridamole, ST depression, RWM abnormalities, and decreased LVEF were observed in 14 (54%), 15 (58%), and 2 (8%) patients, respectively. Although LVEF usually decreases during myocardial ischemia, LVEF did not decrease (57 +/- 11% to 58 +/- 10%), even in patients with ST depression, after intravenous dipyridamole. Maintained left ventricular ejection fraction is considered to be a hemodynamic effect of the potent arterial vasodilatation induced by dipyridamole. These results from dipyridamole-RNV in myocardial ischemia seem to conflict with the results from dipyridamole-thallium studies carried out to determine the capacity to detect coronary artery disease. Unknown mechanisms of dipyridamole other than the coronary steal phenomenon may be operative in the genesis of myocardial ischemia.

Coronary Disease↗
PubMed1990

Development of stable film test for rapid estimation of blood or plasma 3-hydroxybutyrate.

A film test for the rapid detection of plasma/serum 3-hydroxybutyrate (3-OHB) has been developed. The film contains NAD, nitro blue tetrazolium, 3-OHB dehydrogenase, and diaphorase, and the surface is coated with modified biomembrane and can detect 50-1500 microM 3-OHB within 2-3 min. One drop or 50 microliters of plasma/serum or blood is applied to the film, and the violet color is read via reflectance meter after 2 min. Plasma/serum samples greater than 1500 microM 3-OHB can be measured by dilution with saline. In blood with 40% hematocrit, the color developed is 50% less than with plasma/serum, and this was adjusted in the reflectance meter. A good correlation (r = 0.99) was observed between results with automated and film methods and between visual methods and reflectance meter. In insulin-dependent diabetes mellitus, all 3 subjects with positive ketonuria (+ +), 8 of 12 subjects with mild ketonuria (+), and 7 of 25 subjects without ketonuria exhibited elevation of 3-OHB in blood greater than 200 microM. The results indicate that 3-OHB film is valuable not only in the emergency room for the differential diagnosis between ketoacidotic and nonketotic hypersomolar coma but also as a marker for insulin dependency, energy dependency on fatty acid compared with glucose, and metabolic control of diabetes.

3-Hydroxybutyric Acid↗
PubMed1990

Synthesis and biological properties of 1-oxapenems.

Several 2-substituted oxapenems, 1a, 1b and 1c, bearing the hydroxyethyl side-chain at 6 alpha were synthesized in a highly stereoselective manner starting from the commercially available 3 alpha-hydroxyethyl-4 beta-acetoxyazetidinone (5). The stability, in vitro antibacterial activity, and beta-lactamase inhibitory properties of these oxapenems were examined. The 2-isopropyl penem 1c had considerable stability as shown by its t1/2 of 200 minutes in pH 7.0 buffer solution and at 37 degrees C, while the other two 1a and 1b were labile. Interestingly, the antibacterial activity of these compounds paralleled their stability and thus penem 1c showed appreciable MICs, whereas the other two were virtually inactive. All three penems inhibited certain cephalosporinases strongly, but penicillinases only weakly. Thus, the inhibitory spectrum was similar to that for epi-thienamycin B and not the spectrum for clavulanic acid.

Anti-Bacterial Agents↗
PubMed1990

Pemphigus vulgaris associated with pregnancy. A case report from Japan.

We present a case of pemphigus vulgaris which developed during pregnancy. The newborn infant was normal. Bullous lesions were successfully treated by pulse therapy with high-dose corticosteroids. This is, to our knowledge, the first report in English from Japan describing pemphigus vulgaris associated with pregnancy.

Adult↗
PubMed1990

[A study of low-dose intermittent intra-arterial infusion chemotherapy for liver metastasis in colorectal cancer].

Since 1985 we have performed low-dose intermittent intra-arterial infusion chemotherapy using an implantable device for inoperable liver metastasis derived from colorectal cancer. We estimated the efficiency of this treatment in terms of effective rates and survival period. We classified subjects into intra-arterial infusion group and general administration group for comparison. The former group was comprised of 54 cases (37 synchronia, 17 heterochronia) treated with low-dose intermittent intra-arterial infusion (FAM ia) from July 1985 to June 1989. The latter comprised 32 cases (17 synchronia, 15 heterochronia) treated with general chemotherapy (general administration of 5-FU and MMC) for three years before December 1986. Of the 37 cases (23 synchronia, 14 heterochronia) evaluated in the intra-arterial infusion group, we recognized 9 PR cases (24.3%; including 5 synchronia, 4 heterochronia). On the other hand, we found only 1 PR case in the general administration group. The 50% survival period in the intra-arterial infusion group was 370 days (380 days synchronia, 340 days heterochronia), against 260 days (270 days synchronia, 250 days heterochronia) in the general administration group. There were no statistically significant differences between the two groups. Although it was not possible for us to obtain satisfactory results in terms of the efficiency of intermittent low-dose intra-arterial infusion treatment, we have been conducting a randomized study considering drug types, drug administration methods, and background of patients to further investigate the efficiency of arterial infusion treatment.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

[An echocardiographic study of alcoholic cardiomyopathy after total abstinence].

Left ventricular function of alcoholic cardiomyopathy with congestive heart failure was investigated by echocardiography during total abstinence for six months. In five of 13 cases, left ventricular ejection fraction (LVEF) was normalized to 55% or more and left ventricular end-diastolic dimension (LVEDd) was reduced to 5.7 cm or less during the study. In the remaining eight patients, no improvement was observed. In the responsive group, two patients showed an increase of LVEF and a reduction of LVEDd simultaneously, but three showed an earlier change in LVEDd. This normalization of LVEF and LVEDd was recognized from three to 12 weeks after abstinence. No significant differences were detected between the responsive and non-responsive groups concerning their age, daily intake of alcohol and period of drinking, NYHA cardiac functional class, the period of experiencing cardiac symptoms and the cardiothoracic ratio by chest radiography. The ratio of left ventricular radius to wall thickness (R/Th) remained 2.9 or less in all of the responsive group, but seven of eight in the non-responsive group showed 2.9 or more. Left atrial dimension was reduced to the normal range except in one, but its normalization did not correlate with the change of left ventricular function. Consequently, after total abstinence from alcohol intake, both left ventricular end-diastolic dimension and ejection fraction improved rapidly, and their normalization could be highly expected. Echocardiography is very helpful in predicting the effect of total abstinence on left ventricular function in alcoholic cardiomyopathy.

Adult↗