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Biomedical subjects

H Yamashina

Publications and source records attributed to H Yamashina.

At least 19 recordsLinked to original sources
PubMed1996

Clinical application of three-dimensional myocardial imaging: evaluation of efficacy of medical treatment on myocardial perfusion.

To investigate the clinical applicability of the three-dimensional (3D) myocardial imaging using a newly developed system (the Application Visualization System-Medical Viewer), thallium-201 myocardial single photon emission computed tomography was performed in 19 patients with previous myocardial infarction before and after treatment with nisoldipine. We have developed a new method for automatically reconstructing 3D imaging for the stereoscopic evaluation of myocardial perfusion. The left ventricular myocardial volume with a radioisotope count > or = 50% of maximum was calculated by using the conventional surface rendering method. With these images, the effect of nisoldipine on myocardial perfusion was assessed and the myocardial volume with a radioisotope count > or = 50% of maximum was compared. In fifteen (88%) of 19 patients, myocardial perfusion increased in the infarct areas after nisoldipine treatment. Nisoldipine significantly increased the myocardial volume with a radioisotope count > or = 50% of maximum from 141 +/- 17 to 153 +/- 18 ml on the stress 3D imagings. These findings indicate that nisoldipine improved myocardial perfusion during exercise. 3D imaging provided stereoscopic assessment of the changes in myocardial perfusion following treatment with nisoldipine and also detected transient enlargement of the left ventricular lumen induced by exercise.

Aged↗
PubMed1994

Effects of quality and developmental stage on the survival of IVF-derived bovine blastocysts cultured in vitro after freezing and thawing.

Factors affecting viability of IVF-derived bovine blastocysts after freezing and thawing were investigated. A total of 1,101 ova matured and fertilized in vitro were cultured under 2 different conditions, 1) in TCM-199 on granulosa cell monolayers at 5% CO(2) in air and 2) in synthetic oviduct fluid (SOF) medium without somatic cell support at 5% CO(2), 5% O(2), 90% N(2). All blastocysts that developed from the 2 different culture systems were individually classified into 4 grades of embryo quality and were then frozen by conventional slow freezing. Developmental rates of the IVF-derived ova to blastocysts and the survival rates of the frozen-thawed blastocysts were not different between the SOF medium (16 and 49%) and the co-culture system (13 and 61%, respectively). Survival of frozen-thawed blastocysts was affected by embryo quality in both the SOF and co-culture systems (P<0.001). Blastocysts produced in vitro were also individually classified into 3 developmental stages and were then cultured for 3 d in the co-culture system with granulosa cells after freezing and thawing. There was a difference in the survival rate of frozen-thawed embryos between blastocyst developmental stages (early vs mid, P<0.05; mid vs expanded, P<0.01; early vs expanded, P<0.001). The post-thawing survival rate of blastocysts frozen at Day 7 (62%) of culture was higher compared with that of Day 8 (45%), but there was no difference in survival rate between Day 7 and 8 of culture. The results indicate that the quality and developmental stage of blastocysts are important factors influencing their survival after freezing and thawing.

Journal Article↗
PubMed1994

Effect of human leukemia inhibitory factor on in vitro development of parthenogenetic bovine morulae.

The present study was conducted to investigate the effect of human leukemia inhibitory factor (hLIF) addition to synthetic oviduct fluid medium (SOFM) supplemented with human serum (HS) on the development of in vitro matured and parthenogenetically activated bovine oocytes. The oocytes matured for 30 h were exposured to ethanol (7%, 7 min) and cytochalasin B (5 mug/ml, 5 to 6 h). The treated oocytes were cultured for 5 d in SOFM supplemented with HS, and Day-5 morulae were cultured for 2 d in SOFM supplemented with HS and with or without hLIF (5000 U/ml) to investigate the subsequent in vitro development to the blastocyst stage. Of the 1531 oocytes that were parthenogenetically activated, 592 (37.5%) cleaved to the 2- to 8-cell stage and 174 (13.8%) developed to the morula stage. The addition of hLIF at the morula stage resulted in a significantly (P<0.01) higher rate of development to the blastocyst stage in the medium with hLIF (55.9%) than without hLIF (28.9%). The mean cell number per blastocyst developed in the medium with hLIF was also significantly (P<0.01) higher than that developed in the medium without hLIF. To evaluate the viability, 6 parthenogenetically developed blastocysts were transferred to 3 recipient heifers (2 embryos per heifer), while in 2 other recipient heifers estrus was prolonged after transfer. The plasma progesterone levels of the 2 recipient heifers at the 28th day after transfer were 8.1 ng/ml and 9.0 ng/ml, but pregnancy was not observed by ultrasonic scanning. The present results indicate that the addition of hLIF to in vitro-produced, Day-5 parthenogenetic bovine morulae significantly improves the subsequent development to the blastocysts stage; however, the present method still does not promote for development of parthenogenetic fetuses in cattle.

Journal Article↗
PubMed1994

[Clinical meaning of 123I-MIBG myocardial SPeCT in patients with dilated cardiomyopathy].

MIBG-myocardial SPECT was performed on patients with dilated cardiomyopathy (DCM) undergoing treatment with beta blocker (Nipradilol). The findings of MIBG-myocardial SPECT were compared with the changes in cardiac function obtained by echocardiograms. The patients enrolled in the study were seven males who has been diagnosed as definitely suffering from DCM according to diagnostic guidelines provided by the Ministry of Health and Welfare. The patients were aged 57.5 +/- 10.2 years. Following intravenous administration of 111 MBq (3 mCi) of MIBG, myocardial SPECT was taken 20 minutes, and 4 hours later. The washout rate of the left ventricular wall was higher in the unchanged group (40.7 +/- 1.2%) than in the improved group (30.3 +/- 6.1%). Both the early and delayed images showed higher extent and severity scores for the unchanged group than for the improved group. A correlation of LVEF with the washout rates was demonstrated (r = -0.819, p < 0.05). A correlation was also observed between the variations in LVEF before and after beta blocker therapy with the washout rates (r = -0.969, p < 0.01), MIBG-myocardial SPECT suggested possibility of the evaluation of severity and prognosis in the patients with DCM.

3-Iodobenzylguanidine↗
PubMed1993

[Evaluation of biodistribution and imaging of atherosclerotic lesions using 111In-labeled low-density lipoprotein].

111In-labeled low-density lipoprotein (LDL) was administered to Watanabe heritable hyperlipidemic rabbits (WHHL group) and control rabbits (control group) to evaluate its biodistribution and scintigraphic images by gamma-camera and radioactivity of each organ. With external imaging, the heart, liver, kidney, bone and spleen of each rabbit were observed. By setting the region of interest, the liver/heart ratio of the WHHL group was significantly lower than that of the control group (p < 0.05), the plasma half life of LDL was longer and radioactivity in blood, heart and aorta was higher in the WHHL group. Each aorta was autoradiographed and significant accumulation of 111In-labeled-LDL was recognized in the aortic arch, bifurcation of intercostal and celiac artery in the WHHL group. By the use of labeled LDL with the combination of gamma-camera, it is capable of detecting the regulation of lipoprotein metabolism and imaging atherosclerotic lesions externally.

Animals↗
PubMed1990

Analysis of complications of permanent transvenous implantable cardiac pacemaker related to operative and postoperative management in 717 consecutive patients.

A retrospective study on complications especially related to operative or postoperative management was carried out in 1000 pacemaker implantations in 717 patients between September, 1972 and December, 1986. In 33 of our series (4.8%), 24 pacing failure occurred within two weeks of implantation. Flange-type leads had the highest incidence of complications. Wedging the electrode close to the longitudinal axis of the heart was found to be the best placing, assuming that the tip of the electrode and the section immediately adjacent were pointing downward. There were 6 cases of diaphragmatic pacing which could not be corrected through programming. No relation with the position of the electrode could be found. We recommend using bipolar pacing to lower the incidence of diaphragmatic pacing. We also had 9 patients with lead fractures (1.3%); these included 3 cases with silicone insulation breaks and 6 cases with wire fractures which occurred closely proximal to the area where the lead was fixed to the vessels. No relationship between the ratio of lead fractures and their brand was found. Five patients developed infections, all of them late postoperatively, over a period of 8 months to 5 years postop. Of these, there were 3 cases with postoperative prolonged hematoma at the pocket site, and 4 cases which had required lead repositioning because of pacing failure. The incidence of infection in our series was low when compared to previous reports, probably due to local use of one gram of Kanamycin during the operation and active chemotherapy performed short term postoperatively. To manage infection of the skin pocket, the pacemaker was removed and a new pacemaker was implanted in the opposite side. There was 7 early postoperative deaths. One of them due to cardiac tamponade caused by perforation of the cardiac wall by temporary electrode lead. The resustation was unsuccessful.

Adult↗
PubMed1989

[A case of acute massive pulmonary embolism successfully treated with transvenous pulmonary embolectomy by catheter].

A 78-year-old woman, suffering from acute massive pulmonary embolism, was successfully treated with transvenous pulmonary embolectomy by catheter. This patient had been suffering from oppressive chest sensations during exercise, and diagnosed and treated as angina pectoris at a nearby clinic. She consulted our hospital complaining that her chest pains were increasing in frequency. She was admitted to our hospital on July 7, 1988, for coronary angiography (CAG), which she underwent on July 8 by the right femoral approach. After the CAG, she was ordered to rest in bed overnight, with the right inguinal region compressed. 18 hours later, the compression was removed and she was allowed to walk. Soon after she walked to the toilet, she complained of chest discomfort and fell into shock (systolic blood pressure was 60 mmHg). An ECG examination showed a right bundle branch block and an inverted T wave in lead V1-3. An echocardiography showed normal contraction of the left ventricle, but an enlargement of the right ventricle and a flattened interventricular septum. An analysis of arterial blood gas showed hypoxia (Pao2 52.5 mmHg, Paco2, 30.9 mmHg). Acute pulmonary embolism was suspected. 240,000 units of urokinase were administered intravenously, and pulmonary angiography was performed immediately. It revealed that the bilateral pulmonary arteries were almost completely obstructed. Although 720,000 units of urokinase were infused into the pulmonary artery, the obstruction did not improve. At that time, we performed a transvenous pulmonary embolectomy. We used a Judkins R 4 guiding catheter for PTCA made by USCI. The catheter was inserted into the pulmonary artery and clots were aspirated with a syringe.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1988

Effects of enoxacin, ofloxacin and norfloxacin on theophylline disposition in humans.

The effect of three new fluoroquinolones on theophylline kinetics and the urinary excretion of metabolites was studied in 5 healthy subjects (3 male, 2 female). All subjects received serial, single i.v. infusions of theophylline (aminophylline, 250 mg) over 60 min after 200 mg doses of a quinolone (enoxacin, ofloxacin, norfloxacin) every 8 h for 3 consecutive days, the quinolone being administered up to the day following theophylline administration. Pretreatment with ofloxacin and norfloxacin did not influence theophylline disposition, but theophylline clearance fell from 0.054 to 0.027 l.h-1.kg-1 in the presence of enoxacin, without a change in the apparent volume of distribution. Enoxacin, too, was the sole compound to increase the urinary excretion of theophylline (33.2 vs 43.9 mg, before vs after treatment), and significantly to decrease the excretion of 3-methylxanthine (3-MX), 1-methyluric acid (1-MU) and 1,3-dimethyluric acid (1,3-DMU) in 24-h urine samples (from 19.8 to 7.16 mg, from 28.3 to 10.3 mg and from 68.8 to 49.5 mg, respectively). The effect of the quinolones on hepatic drug metabolizing enzyme activity was investigated in each subject using the ratios of 6-hydroxycortisol to total 17-hydroxycorticosteroids and to free cortisol in 24-h urines as an index of the hepatic P-450-dependent enzyme system. No significant difference in ratio was observed between control and other treatments. It is concluded that the theophylline-enoxacin interaction was largely due to inhibition of a metabolic system other than the common hepatic P-450 system.

17-Hydroxycorticosteroids↗
PubMed1987

Effect of valproic acid on pharmacokinetics of active metabolites of cyclophosphamide in mice.

The effects of valproic acid (VPA) on pharmacokinetics of cyclophosphamide (CPM) alkylating metabolites were investigated in male BALB/c mice. The pharmacokinetics of CPM alkylating metabolites was found to be dose-dependent representing the decrease of formation and elimination rates of the metabolites. A nonlinear increase of area under blood concentration of CPM alkylating metabolites-time curve (AUC) occurred with increasing CPM dose of 100, 200, and 300 mg/kg body weight. The effects of VPA (100 mg/kg dose) coadministered with CPM were similar to those of the increase of the CPM dose in preventing the activation of CPM and the elimination of its alkylating metabolites. The delayed disposition of CPM alkylating metabolites resulted in a 1.5-fold increase (p less than 0.02) of AUC which was considered the most important pharmacokinetic parameter in the CPM therapy. VPA which was injected i.p. at a dose of 100, 200, or 300 mg/kg increased the pentobarbital induced-sleep time by 81, 138, or 192%, respectively. In order to assess the effect of VPA on drug metabolizing enzyme(s) activity in humans, the ratio of daily urinary 6-hydroxycortisol to 17-hydroxycorticosteroids, which can reflect cytochrome P-450 activity, was determined in 5 healthy volunteers. The ratio was rapidly and significantly decreased (p less than 0.05) and this reduction continued during VPA administration. These findings and those reported in the literature concerning CPM metabolism suggest that the delay of CPM alkylating metabolites elimination resulted in part from microsomal enzyme(s) inhibition by VPA.

Animals↗
PubMed1987

[Prophylactic effects of cefmenoxime against postoperative infections after thoracotomy. Studies of cefmenoxime transfer from serum to pleural fluid and of clinical effects of cefmenoxime].

Cefmenoxime (CMX) at a dose of 1 g was administered intravenously to each of 10 patients undergoing thoracotomy, and concentrations of CMX in the serum and pleural fluid were measured. Serum concentration of CMX reached its peak of 43.71 micrograms/ml at 1 hour and decreased to 4.15 micrograms/ml at 3 hours after the administration. The concentration of CMX in the pleural fluid reached its peak of 7.61 micrograms/ml at 3 hours and decreased slowly 5.26 micrograms/ml at 7 hours after the administration. A clinical study with 21 patients was performed to evaluate the effect of CMX as a prophylactic antimicrobial agent in thoracotomy. Patients received intravenous administration of 4 g/day of CMX for 7-10 days following operations. Each patient was evaluated daily for fever, sign of allergic reaction, and wound infection and other symptoms. No apparent infection occurred in those clinical patients except 1 patient with a suspected infection, and 1 case of allergic reaction as exanthema was observed during this study. Prophylactic effect of CMX against postoperative infection after thoracotomy was good.

Adult↗