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Biomedical subjects

Y Kihara

Publications and source records attributed to Y Kihara.

At least 91 records · Page 5Linked to original sources
PubMed1995

[A case of aortic bicuspid valvular endocarditis with congenital left ventricular diverticulum].

A 29-year-old man had a prolonged fever and painful Osler's nodes on his right foot. The aortic valve was bicuspid with vegetation mass and the left ventricular diverticulum was additionally present connecting with the left ventricular outflow tract. An operation was performed after intravenous administration of antibiotics for 3 weeks. The aortic bicuspid valve and the vegetation were removed and replaced by an artificial valve (SJM-HP 19 mm). The left ventricular diverticulum was resected. The echocardiographic findings correlated well with the intraoperative observation.

Adult↗
PubMed1994

Clinical effects of long-term administration of pimobendan in patients with moderate congestive heart failure.

The long-term efficacy of the positive inotropic and vasodilator drug, pimobendan, was assessed in 21 patients suffering from symptomatic heart failure. Patients were randomized to 16 weeks of double-blind therapy with either 2.5 or 5.0 mg/day of pimobendan (n = 10), or a matching placebo (n = 11). Patients were blinded on the study drug if their clinical status had not substantially worsened during the study. Of the placebo-treated patients, 5 patients were withdrawn from the study because of a deterioration of their heart failure, while none of the active treated group was withdrawn because of increased symptoms. Quality of life, assessed by the specific activity scale derived from the metabolic costs of individual physical activity, was 3.45 +/- 0.90 (SD) mets in the baseline state and increased significantly after week 16, averaging 5.07 +/- 1.40 and 4.67 +/- 1.47 mets at weeks 16 and 24, respectively. In the placebo-treated group, the specific activity scale was 3.27 +/- 1.21 mets at the baseline and remained unchanged throughout the study period. Patients treated with pimobendan were able to significantly increase their exercise duration. The accompanying increase in peak oxygen uptake was statistically insignificant, due to the limited number of patients enrolled in the study. These results suggest that in contrast to the recent pessimistic view of the long-term efficacy of cardiotonic drugs, pimobendan is beneficial in treating patients with congestive heart failure and may favorably modify their prognosis. Further large-scale evaluation of this agent is warranted.

Activities of Daily Living↗
PubMed1994

Magnetic resonance imaging of bone marrow changes after irradiation.

RATIONALE AND OBJECTIVES: Signal changes of irradiated bone marrow are thought to represent fatty change. However, more recent studies have indicated that other factors may contribute to these signal changes. We performed animal studies to investigate magnetic resonance (MR) signal change factors in correlation with histologic findings. MATERIALS AND METHODS: Forty-two male Wistar rats were given single doses (3, 8, and 20 Gy) of irradiation. Magnetic resonance imaging (1.5 T) was performed using spin-echo technique. RESULTS: In the acute phase (days 1-3), the T1 time was prolonged, probably secondary to decreased cellularity and edema. After this phase, the irradiated marrow showed marked T1 and T2 shortening that correlated with hemorrhage. In the chronic phase (after day 10), fatty replacement, fibrosis, and regeneration were observed. T2 times were stable in spite of regeneration because of the susceptibility effect of hemosiderin. CONCLUSION: The MR signal changes of irradiated marrow reflect not only fatty replacement, but hemorrhage as well.

Animals↗
PubMed1994

Transition from compensatory hypertrophy to dilated, failing left ventricles in Dahl salt-sensitive rats.

To establish an experimental model for studying a specific transitional stage for compensatory hypertrophy to heart failure, we studied the pathophysiology of the left ventricle (LV) in Dahl salt-sensitive (DS) rats fed a high-salt diet. DS rats fed an 8% NaCl diet after the age of 6 wk developed concentric LV hypertrophy at 11 wk, followed by marked LV dilatation at 15-20 wk. During the latter stage, the DS rats showed labored respiration with LV global hypokinesis. All the DS rats died within 1 wk by massive pulmonary congestion. The dissected left ventricles revealed chamber dilatation and a marked increase in mass without myocardial necrosis. In contrast, corresponding Dahl salt-resistant (DR) rats fed the same diet showed neither mortality nor any of these pathological changes. The in vivo LV end-systolic pressure-volume relationship shifted to the right with a less steep slope in the failing DS rats compared with that in age-matched DR rats. Isometric contractions of LV papillary muscles isolated from these DS rats showed reduced tension development in the failing stage, but normal tension development in the hypertrophied stage. In conclusion, the DS rat fed a high-salt diet is a useful model showing rapidly developing congestive heart failure, in which the transition from compensatory hypertrophy to decompensatory dilatation of LV is easily and consistently manifested.

Animals↗
PubMed1994

Sodium/calcium exchange modulates intracellular calcium overload during posthypoxic reoxygenation in mammalian working myocardium. Evidence from aequorin-loaded ferret ventricular muscles.

We tested the hypothesis that the intracellular Ca2+ overload of ventricular myocardium during the period of posthypoxic reoxygenation is mediated by transsarcolemmal Ca2+ influx via Na+/Ca2+ exchange. In aequorin-loaded, ferret right ventricular papillary muscles, blockers of the sarcolemmal and the sarcoplasmic reticulum Ca2+ channels, slowed the Cai2+ transient, producing a convex ascent during membrane depolarization, followed by a concave descent during repolarization. The magnitude of the Cai2+ transient was affected by changes in the membrane potential, Nai+, Nao+, and Cao2+, and was blocked by Ni2+, or dichlorbenzamil. The calculated Na+/Ca2+ exchange current was in the reverse mode (Ca2+ influx) during the ascending phase of the Cai2+ transient, and was abruptly switched to the forward mode (Ca2+ efflux) at repolarization, matching the time course of the Cai2+ transient. During hypoxic superfusion, the Cai2+ transient was abbreviated, which was associated with a shorter action potential duration. In contrast, immediately after reoxygenation, the Cai2+ transient increased to a level greater than that of the control, even though the action potential remained abbreviated. This is the first demonstration on a beat-to-beat basis that, during reoxygenation, Ca2+ influx via Na+/Ca2+ exchange is augmented and transports a significant amount of Ca2+ into the ventricular myocardial cell. The activation of the exchanger at the time of reoxygenation appears to be mediated by Nai+ accumulation, which occurs during hypoxia.

Action Potentials↗
PubMed1994

[Comparison of treatment results of prostatic cancer between radical prostatectomy and radiation therapy].

Between 1982 and 1990, 55 patients with prostate cancer (clinical stage A2-C) underwent pelvic lymphadenectomy at the Public Toyooka Hospital. The patients were subsequently treated either by radical prostatectomy (36 cases) or external radiation therapy (19 cases). The age of the patients varied from 56 to 85 (Mean 73.1). The outcome of the 46 patients with negative lymph node (prostatectomy 31, radiation 15) were compared. The 10-year disease-specific survival rates were 100% for the patients treated by prostatectomy and 78% for those treated by radiation (P = 0.035). The 5-year progression-free survival rates for the prostatectomy group and radiation group were 97% and 56%, respectively (P = 0.013). Among the radiation groups, patients with well differentiated carcinoma showed a lower progression rate as compared to those with moderately or poorly differentiated carcinoma (5-year progression-free survival, 81 vs 20%, P = 0.094). The outcome of the 9 patients with positive lymph node (prostatectomy 5, radiation 4) was not satisfactory because of the high progression rates in the two groups (5 year progression-free survival, 30% in prostatectomy and 25% in radiation group).

Aged↗
PubMed1994

[Clinical and statistical studies on prostatic cancer: prognostic value of clinical stage, Gleason score and age].

We assessed the outcome of 200 patients with prostatic cancer treated at the Public Toyooka Hospital from 1980 to 1989. The patient's age varied from 53 to 94 years (mean 76.8). Overall actuarial survival rate at 5 and 10 years were 52% and 25%, respectively. The 5-year survival according to clinical stage was 69% for stage A, 66% for stage B, 43% for stage C and 32% for stage D disease. A significant difference was noted between the survival of patients with stage A or B and those with stage C or D. Patients with Gleason score of less than 7 showed significantly better survival as compared to those with Gleason score of 7 or more (5-year survival, 64% vs 33%). No significant difference was observed between the survival of patients under the age of 75 and those 75 or older.

Age Factors↗
PubMed1994

[Assessment of treatment outcome and prognostic factors of renal cell cancer].

We assessed the treatment outcome of 71 patients (45 men and 26 women) with renal cell cancer treated at the Public Toyooka Hospital from 1969 to 1992. The patient's age varied from 15 to 85 (mean 64). The overall actuarial and disease specific survival rates at 5 years were 55% and 67%, respectively. Statistical analysis of various parameters associated with prognosis was performed. The parameters achieving statistical significance were pT, PV, distant metastasis, grade, histological architecture, cell type, tumor size and erythrocyte sedimentation rate.

Adolescent↗
PubMed1993

Metallosis caused by alumina ceramic screw fixation of grafted bone in a bipolar hip endoprosthesis.

We report a case of metallosis due to ceramic fragments in the inner bearing surface of the polyethylene cup of a bipolar hip prosthesis with fracture of the alumina ceramic screws used for grafted bone fixation. After bone-grafting acetabuloplasty with a Bateman bipolar endoprosthesis, gradual migration of the outer head occurred, and fracture of the screws was observed. Seven years after the operation, radiographs showed severe metallosis of the surrounding tissues. At revision, marked wear of the inner head was seen. Detailed examination revealed that many rough-edged ceramic particles originating from the fractured ceramic screws had become embedded in the inner surface of the polyethylene bearing insert. These extremely hard ceramic fragments had entered the prosthetic joint space during joint movement, thereafter causing continuous abrasion of the metal head. After revision, the concentration of the constituents of the prosthesis alloy in the serum decreased toward control levels. To prevent serious complications like those in the present case, screws should be inserted more than 1 cm from the outer head of a bipolar endoprosthesis, and the outer head should be removed as soon as possible if it comes into contact with the screws.

Acetabulum↗
PubMed1993

Fluorocarbon simulation of myocardial ischaemia and reperfusion: studies of relationships between force and intracellular calcium.

OBJECTIVE: The aim was to compare the effects of simulated ischaemia-reperfusion with those of hypoxia-reoxygenation in isolated muscle preparations from the ferret right ventricle. METHODS: Ischaemia was simulated using fluorocarbon immersion plus hypoxia. Intracellular calcium transients were determined from aequorin luminescence during isometric contractions. RESULTS: Hypoxia in fluorocarbon and physiological saline solution resulted in a similar reversible depression of the peak of the calcium transient. Peak active tension, however, was more depressed in fluorocarbon than in physiological salt solution. The dissociation between peak light and peak active tension was most pronounced on reoxygenation, with near complete recovery of peak light, while there was little recovery of tension in fluorocarbon. When fluorocarbon was then replaced by physiological salt solution, peak active tension recovered promptly. A prolongation of the decay of the calcium transient was seen in both fluorocarbon and physiological salt solution during hypoxia, which shortened promptly on reoxygenation. The time to the peak of the calcium transient was most prolonged during hypoxia in fluorocarbon and there was gradual recovery on reoxygenation. CONCLUSIONS: While some changes in the calcium transient during simulated ischaemia are rapidly reversible with reoxygenation (in fluorocarbon), suggesting an effect of hypoxia, others are incompletely reversed or only reversed with physiological salt solution, suggesting an effect of metabolite accumulation. The pronounced dissociation between peak light and peak active tension during reoxygenation in fluorocarbon is promptly reversed by changing to physiological salt solution, suggesting that metabolite retention in the postischaemic period may contribute to depressed myocardial function after reperfusion.

Animals↗
PubMed1993

Assessment of sudomotor dysfunction in early Parkinson's disease.

We performed a quantitative sudomotor function test on 10 patients with early Parkinson's disease (PD) and 11 age-matched control subjects. Thermal warming increased the sweat rate in both PD and controls. There was no difference in sweat rate between the forearm and the thigh in either PD or controls. In PD, thyrotropin-releasing hormone (TRH) did not increase the sweat rate, whereas it did so in the controls. These results suggest that sudomotor dysfunction in early PD is minor but that there may be an impairment of TRH-induced sympathetic response in the early stages of PD.

Forearm↗
PubMed1993

[Treatment results of total cystectomy for patients with bladder cancer].

We assessed the treatment outcome of total cystectomy for 93 patients (71 men and 22 women) with bladder cancer treated in the Public Toyooka Hospital from 1970 to 1989. Patient age varied from 36 to 87 (mean 67). The overall actuarial survival rates at 5 and 10 years were 51% and 36%, respectively. The 5-year survival rates were 72% for grade 2 and 44% for grade 3 disease. The 5-year survival rates according to the pathological stage were 66% for pT0-1, 51% for pT2, 35% for pT3, 44% for pT4a disease. A statistical difference was noted between the 5-year survival rate of patients with pT0-2 disease and that with pT3. Patients with pT4aN0 disease showed a relatively high survival rate (67%). The 5-year survival rates were 54% for the patients with negative lymph node and 22% for those with positive lymph node. Although we could not demonstrate the efficacy of preoperative radiotherapy, the combination of radiation and chemotherapy was suggested to improve the survival after cystectomy. Patients who received simultaneous urethrectomy showed a higher 5-year survival rate as compared to those who did not.

Adult↗
PubMed1993

[E-C coupling of the failing myocardium].

Calcium ion (Ca2+) plays a central role in regulating E-C coupling in the heart. Intracellular Ca2+ homeostasis is maintained when all of subcellular steps for Ca2+ handling are functioning synchronously. Many investigators have proposed that the pathophysiologic basis for abnormal mechanical characteristics of the failing myocardium may be disturbed intracellular Ca2+ handlings, at one or more of the cellular sites. Recent advances of Ca2+ indicators have enabled to directly study the hypothesis in actively contracting myocardium. In acute contractile failure with ischemia or hypoxia, cellular sites or materials which block the normal E-C coupling have been mostly identified. For the mechanisms of abnormal contractions in the chronic failing myocardium, investigations are going on by using several experimental models and human hearts.

Animals↗
PubMed1993

[Clinical significance of multiple mucosal biopsies in new cases of superficial papillary bladder tumor].

We assessed the clinical significance of multiple mucosal biopsies in new cases of superficial papillary bladder tumor. Biopsy findings were abnormal (5 dysplasia, 5 transitional carcinoma) in 10 of the 71 cases examined. Abnormalities were observed exclusively at G2 or G3, and more frequently at pT1 than pTa. Cases with multiple tumors showed significantly more abnormalities than cases with a solitary tumor. Recurrence rates were not significantly different between the cases with abnormal biopsy findings and those with normal findings. However, the invasive tumor developed more frequently in the former. Mucosal biopsies seemed to be more useful in cases with multiple tumors than in those with a solitary tumor.

Adult↗
PubMed1992

Right anterior caudocranial oblique projection for portal venography; its indications and advantages.

Right anterior caudocranial oblique (RACCO) projections were evaluated for transarterial portography with digital subtraction angiography. For RACCO projection, the image intensifier was tilted 25 degrees caudally and 30 degrees to the patient's right with the patient in the supine position. The abnormal findings imaged in 20 patients were analyzed by types of abnormalities and their locations in the portal venous systems by comparing RACCO and PA projections. The RACCO view was superior to the PA projection for demonstrating either encasements or tumor thrombi in relatively proximal segments of the portal venous branches. Two encasement lesions and a tumor thrombus were imaged only on the RACCO projection. However, the RACCO projection had no definite advantage over the PA view for showing encasements or tumor thrombi in the distal segmental branches. The RACCO projection was superior to the PA view for demonstrating defects in the hepatograms of some hepatic segments (S5 and S8). We concluded that the RACCO view is extremely useful and is indicated for angiographic work-ups of hepatic or biliary lesions when abnormalities are suspected in proximal portal venous branches.

Angiography, Digital Subtraction↗