Biomedical subjects

T Ohno

Publications and source records attributed to T Ohno.

At least 991 records · Page 55Linked to original sources

PubMedDate not supplied

Set-up, improvement, and evaluation of an electrohydraulic total artificial heart with a separately placed energy converter.

The authors have been developing an electrohydraulic total artificial heart (TAH) system with a separately placed electrohydraulic energy converter to minimize anatomic constraints in the pericardial space. Improvements to the system and current status of the development are reported. The energy converter was miniaturized to improve implantability, and its thickness was reduced to 54 mm. System efficiency was increased by suppressing rush current at the time of motor reversal. Maximum cardiac output of the TAH system was 9 L/min, and maximum system efficiency increased to 10%. The blood pump system was implanted easily in the body of a 57 kg calf, and no significant temperature rise on the energy converter surface was observed. As the next step, main components were integrated into a total system. The transcutaneous energy transfer system could supply power to the TAH without a decline in pump performance, and the internal battery could support the system at 6.5 L/min of cardiac output for 1 hour without a decrease in cardiac output. The authors consider the TAH system with a separately placed energy converter the most promising approach to development of a TAH for smaller sized patients.

Animals↗

PubMedDate not supplied

Development of a precise controller for an electrohydraulic total artificial heart. Improvement of the motor's dynamic response.

In an electrohydraulic total artificial heart developed at the National Cardiovascular Center (Osaka, Japan), two blood pumps are pushed alternatively by means of the bidirectional motion of a brushless DC motor for pump systole and diastole. Improvement in the dynamic response of the motor is very important to obtain better pump performance; this was accomplished by using power electronic simulation. For the motor to have the desired dynamic response, it must be commutated properly and the damping ratio (zeta), which represents transient characteristics of the motor, must lie between 0.4 and 0.8. Consequently, all satisfactory specifications with respect to power consumption must be obtained. Based on the simulated results, the design criteria were determined and the precise controller designed to reduce torque ripple and motor vibration, and determine motor stop time at every direction change. In in vitro tests, evaluation of the controller and dynamic response of the motor was justified in terms of zeta, power consumption, and motor stop time. The results indicated that the power consumption of the controller and the input power of the motor were decreased by 1.2 and 2.5 W at zeta = 0.6, respectively, compared to the previous system. An acceptable dynamic response of the motor, necessary for the reduction of torque ripple and motor vibration, was obtained between zeta = 0.5 and zeta = 0.7, with an increase in system efficiency from 10% to 12%. The motor stop time required for stable motor reoperation was determined to be over 10 msec, for a savings in power consumption of approximately 1.5 W. Therefore, the improved dynamic response of the motor can contribute to the stability and reliability of the pump.

Biomedical Engineering↗

PubMedDate not supplied

Influence of non pulsatile systemic circulation on tissue blood flow and oxygen metabolism.

Influence of non pulsatile systemic circulation on oxygen metabolism was examined regarding tissue perfusion in 12 adult goats weighing from 46 to 55 kg. Under general anesthesia, a flow character, changeable total left heart bypass circuit consisting of pulsatile and non pulsatile pumps was installed through a left thoracotomy. Systemic flow was converted from pulsatile to non pulsatile in 7 of 12 animals, and in the reverse order in the other 5, by changing the driving pump. Esophageal mucosal blood flow was determined by a colored microsphere method that estimated tissue blood flow at the pre capillary level. Esophageal intramucosal pH was evaluated with a silicone balloon tonometer catheter surgically placed in the submucosal space. Hemodynamic and arterial blood gas parameters were unchanged at flow mode conversion. Although oxygen delivery was comparable between pulsatile and non pulsatile circulation, oxygen extraction ratio was lower and venous oxygen saturation was higher in non pulsatile than pulsatile circulation. Although statistically not significant, serum lactate level tended to be higher with non pulsatile circulation. No difference was observed in esophageal mucosal blood flow between pulsatile and non pulsatile circulation, whereas intramucosal pH, which strongly correlated with arterial pH regardless of the flow mode, was significantly lower under non pulsatile than pulsatile conditions. In conclusion, systemic oxygen uptake is less efficient in non pulsatile than pulsatile circulation in the setting of an acute experiment using animals, which may be accounted for by the disparity between the pre capillary blood flow and actual tissue oxygen metabolism.

Animals↗

PubMedDate not supplied

Importance of metabolic function of the natural lung evaluated by prolonged exclusion of the pulmonary circulation.

It is generally considered that the natural lung metabolizes various vasoactive substances through the pulmonary circulation. However, the influences of bypassing or eliminating the pulmonary circulation have not been fully elucidated, especially for prolonged periods. In this study, we performed total cardiopulmonary bypass and exclusion of the pulmonary circulation for up to 336 hr in awake goats to clarify the importance of the metabolic function of the lung. In seven adult goats, biventricular bypass with a pulsatile ventricular assist system was first established. After 2 weeks, the biventricular bypass was converted to total cardiopulmonary bypass without anesthesia. Adequate gas exchange and perfusion support were achieved in all animals. However, the institution of total cardiopulmonary bypass led to marked decreases in the mean aortic pressure and systemic vascular resistance, and they remained low thereafter. The arterial levels of prostaglandin E2 and norepinephrine, which are inactivated naturally through the pulmonary circulation, increased remarkably. These results indicate that the natural lung plays an important role in controlling systemic circulation by metabolizing various vasoactive substances. Understanding the non respiratory function of the natural lung is of prime importance for advancement of lung and heart-lung support.

Animals↗

PubMedDate not supplied

Development of an integrated artificial heart-lung device for long-term cardiopulmonary support.

An integrated artificial heart-lung device has been developed as a long-term cardiopulmonary support system. The device is composed of gas exchange and pumping units. The gas exchange unit consists of a special hollow fiber membrane that can prevent serum leakage. The entire blood contacting surface of the gas exchange unit is treated with covalent heparin bonding. The pumping unit consists of two pusher-plate artificial hearts joined to each end of the artificial lung unit. The core size and priming volume of the device are 11 x 14 x 17 cm and 400 ml, respectively. In in vitro evaluation, the device exhibited a maximum output of 7.0 L/ min, with a pressure gradient of 10 mmHg per 1 L/min flow rate. In acute in vivo evaluation with adult goats, the device satisfactorily replaced the animals' circulation and respiration for 6 hr. Pumping output ranged from 5.5 to 6.0 L/min, whereas PaO2 and PaCO2 were kept above 500 mmHg and below 30 mmHg, respectively. The device demonstrated prominent thrombus resistant properties in nonheparin animal use trials. These results indicate that the integrated artificial heart-lung device has a potential to be a long-term cardiopulmonary support system that can be used with minimal anticoagulant therapy.

Animals↗

PubMedDate not supplied

Development of a membrane oxygenator for long-term respiratory support and its experimental evaluation in prolonged ECMO.

The authors developed a new membrane oxygenator (MO) for long-term respiratory support and evaluated its performance in animal experiments for as long as 336 hr. The MO, with a membrane area of 1.2 m2 and priming volume of 140 ml, is compact and designed to be interposed in a ventricular assist system (VAS) conduit. It is made with a novel hollow fiber membrane, in which micropores are blind-ended so that serum leakage can be prevented during prolonged use. The blood contacting surface of the MO is heparinized with a newly developed covalent bonding technique that ensures good thrombus resistance. In vivo evaluation with five adult goats was performed by installing the MO into a venoarterial or venovenous bypass circuit. No systemic anticoagulant therapy was used, except for a heparin-added fluid infusion to keep the pressure monitoring lines open (2-3 U/kg/hr). Throughout the experiments, no plasma leakage was observed, and gas transfer rates were maintained in a satisfactory range. Platelet counts did not decrease to less than 60% of levels before bypass, and hemolysis was negligible. The levels of coagulation parameters including fibrinogen, fibrin degradation products (FDP), antithrombin III (AT III), antiplasmin, prothrombin time (PT) and activated partial thromboplastic time (APTT) remained within physiologic ranges and relatively constant. At the end of the evaluation, no thrombus formation was noted in three of five MOs. These results suggest that this MO is a promising device for long-term respiratory support.

Animals↗

PubMedDate not supplied

Altered oxygen metabolic conditions associated with increased norepinephrine levels in a nonpulsatile systemic circulation.

Change in oxygen metabolic conditions accompanying the conversion of systemic flow from pulsatile to nonpulsatile (from P-mode to N-mode) was investigated in association with blood norepinephrine levels. Total left heart bypass was instituted through a left thoracotomy under general anesthesia in 10 adult goats. Pulsatile and nonpulsatile pumps were incorporated in the circuit in parallel, and the flow character was rapidly converted from the P-mode to the N-mode. Norepinephrine levels increased significantly after the conversion, from 222 +/- 54 pg/ml to 285 +/- 65 pg/ml. While oxygen delivery (DO2) was kept constant, the oxygen extraction ratio significantly decreased, from 21 +/- 3% to 16 +/- 3%, and venous oxygen saturation (SvO2) significantly increased, from 77 +/- 6% to 84 +/- 6% after depulsation. The serum lactate level was significantly higher in the N-mode than the P-mode (P-mode: 35 +/- 2 mg/dl, N-mode: 45 +/- 5 mg/dl). Strong positive and negative correlations of norepinephrine levels were observed with oxygen extraction ratio and SvO2, respectively, whereas norepinephrine levels did not correlated with DO2. Regression lines in these correlations unveiled higher oxygen uptake in the P-mode than the N-mode at the same norepinephrine level. These results indicate that, in the setting of an acute animal experiment, oxygen uptake is less efficient with the absence of pulsatility, and the higher norepinephrine concentration functioned to tune the oxygen metabolism in the initial stage of nonpulsatile systemic circulation.

Animals↗

PubMedDate not supplied

Control of a total artificial heart using mixed venous oxygen saturation.

We developed a control of the total artificial heart (TAH) using mixed venous oxygen saturation (SvO2). With this method, the TAH output was controlled by automatically adjusting drive parameters in response to changes in measured SvO2. The feasibility and validity of this method were evaluated in a series of treadmill exercise tests using a calf implanted with a pneumatic TAH. The cardiac output (CO) and SvO2 were measured with an ultrasonic flowmeter and an oximetric catheter, respectively. The calf performed graded exercise under a fixed drive control mode (fixed mode), in which the drive parameters were unchanged throughout the treadmill test, and under the SvO2 based control mode (SvO2 mode). The calf could go to Stage 6 in both modes, but the maximal oxygen consumption in the SvO2 mode was 1.5 times as large as that of the fixed mode. Compared with the fixed mode, CO was increased effectively in the SvO2 mode, and the capacity for exercise was augmented. When considering the relationship between oxygen consumption and oxygen delivery, it was revealed that the CO in the SvO2 mode responded more adequately to the recipient's oxygen demand than that in the fixed mode. We conclude that this SvO2 based control method is feasible and physiologically effective.

Animals↗

PubMedDate not supplied

MR angiography of renal vascular malformations.

OBJECTIVE: We wanted to determine whether three-dimensional phase contrast (3DPC) MR angiography is clinically useful in the diagnosis of renal vascular malformations. MATERIALS AND METHODS: Three-dimensional PC MR angiography was performed in 22 patients with gross hematuria and in 8 healthy volunteers. Small flip angles and 60 cm/s velocity encoding best demonstrated the normal intrarenal arteries with arteriovenous differentiation in the eight healthy volunteers. In the 22 patients with gross hematuria, intraarterial digital subtraction angiography demonstrated cirsoid-type malformations in 6 patients, aneurysmal-type malformations in 3 patients, and normal vascular anatomy in 13 patients. RESULTS: Magnetic resonance angiography detected all three aneurysmal-type malformations and four of the cirsoid-type malformations. Small cirsoid-type malformations were not detected in two patients. The moderate or large malformations were demonstrated as dilated and tortuous feeding arteries and high intensity renal veins with high flow velocity. We found no correlation between signal intensity in the suprarenal inferior vena cava and the presence of arteriovenous shunts. There were no false-positive cases. CONCLUSION: Sensitivity, specificity, and accuracy in this series were 78, 100, and 91%, respectively.

Adolescent↗

PubMedDate not supplied

Swim-down separation of progressively motile sperm from poor quality human semen by the modified funnel procedure.

The simultaneous swimming up and down from identical semen specimens suggested that the separation efficiency of progressively motile sperm by the swim-down method was superior to that of the swim-up method. The swimming down was performed in a small plastic funnel, the bottom of which was plugged with a 2.5 ml disposable syringe. In this funnel, 2.0 ml of 70% Percoll was poured and then the sperm resuspension was overlaid. After 1 h, progressively motile sperm penetrating into the lower part of Percoll layer (1.6 ml) was collected in the syringe. The technical strategies to yield higher density of progressively motile sperm were found to be centrifugal concentration of the sperm from whole ejaculate prior to the swimming down, and subsequent re-centrifugation of the separated sperm after the swimming down. Oligo-asthenozoospermic semen (22 +/- 4.4 x 10(6) ml1, 5.5 +/- 4.4% motility, n = 8) was processed by the present method, yielding sperm qualities of 32 +/- 19 x 10(6) ml1, 74 +/- 14% in the final preparations. Overall improvement in fertility index (sperm density ml1 x motility % x 10(8)) reached 27-folds on average.

Cell Separation↗

PubMedDate not supplied

Concentrating human sperm before cryopreservation.

To improve the quality of cryo-preserved sperm, ejaculated semen was concentrated prior to freezing by means of continuous-step density gradient centrifugation. Freezing was simplified by employing liquid nitrogen vapor with KS-II cryo-medium. The original semen (n = 32, 41 +/- 13 x 10(6)/ml, 17 +/- 11% motility) was improved by the processing to be 68 +/- 29 x 10(6)/ml, 55 +/- 19% motility. Even after the specimens were thawed, sperm concentrations were similar to those of the original semen and 39 +/- 18% motility remained with a mean survival rate of 74 +/- 7.7%. The improved sperm motility and higher survival rate resulted in better post-thaw sperm quality than those of the original semen.

Cell Survival↗

PubMedDate not supplied

Intrauterine insemination with semen of oligozoospermic men: effectiveness of the continuous-step density gradient centrifugation technique.

There has been an argument as to whether the intrauterine insemination (IUI) substantially improves pregnancy rate in cases of oligoasthenozoospermia. The present study evaluates the efficiency of the IUI with the use of the life table analysis. The insemination was performed after washing and concentrating sperm using the continuous-step density gradient centrifugation reported in our previous papers. The number of IUI cycles studied was 222 (46 couples), in 13 cases of which pregnancy was established with a pregnancy rate of 28.3%. The cumulative probability of conception reached to 57% at the eleventh cycles of the IUI treatment. These results suggest that the potential efficiency of the IUI for the oligo-asthenozoospermic cases is high if the sperm is processed in a proper method.

Adult↗

PubMedDate not supplied

Cystic lymphangioma of the gall-bladder: a case report.

Intra-abdominal cystic lymphangiomas are rare lesions that can be difficult to diagnose. We present a report of a patient with a giant multilocular cystic lesion in the abdomen. Ultrasonography and computed tomography scans of the abdomen revealed that the cyst had originated in the gall-bladder fossa. There was some calcification and thickening of the cyst wall. Endoscopic retrograde cholangiopancreatography demonstrated a medially deviated common bile duct, an elongated cystic duct and an inferior compressed gallbladder. There was no apparent communication between the cyst and the biliary tract; however, an abdominal angiogram revealed that the lesion was supplied by a branch of the cystic artery. Histological findings obtained intra-operatively were consistent with a cystic lymphangioma. Its characteristic histology was observed in the subserous layer of the gall-bladder. This case is a rare instance of a cystic lymphangioma originating in the gall-bladder.

Adult↗

PubMedDate not supplied

Prognostic significance of c-erbB-2/HER2 expression in advanced uterine cervical carcinoma with para-aortic lymph node metastasis treated with radiation therapy.

This paper looks at whether c-erbB-2/HER2 expression in uterine cervical carcinoma before treatment is a predictive parameter of prognosis in patients with para-aortic lymph node metastasis (PALN) in advanced disease after treatment with radiation therapy (RT). Twenty-one patients with PALN at the first visit and/or during follow-up and treated with RT for PALN lesions were studied. Their clinical stages were IIIB or greater and they were referred to the National Institute of Radiological Sciences Hospital for RT between 1987 and 1995. They consisted of 12 patients with PALN detected at the first visit and nine with PALN detected during the follow-up period. All patients had no distant metastasis except PALN. They were treated with a combination of external whole pelvis and intracavitary irradiation to the primary pelvic lesions. The PALN was treated with external irradiation alone with anterior-posterior parallel opposed fields and anterior oblique fields or anterior-posterior parallel opposed oblique fields. The average total dose to PALN was 53.3 Gy (40-61Gy). Tissue samples were obtained from cervical tumors (primary lesions) before RT. Immunohistochemical staining was performed using anti-c-erbB-2/HER2 monoclonal antibody for conventional paraffin sections. c-erbB-2/HER2 positive staining was observed in cancer membrane and cytoplasm. Nine specimens were positive for c-erb-B2/HER2 and the total positive rate was 43%. The 5-year survival rate was 38% for all patients. The 5-year survival rate of the c-erbB-2/HER2 positive patients was 28%, representing a trend toward poorer prognosis than the 52% of negative patients (P = 0.10). Multivariate analysis using Cox proportional hazards model showed that c-erbB-2/HER2 was an independent prognostic factor (P = 0.024). The present study suggests that c-erbB-2/HER2 expression of cervical tumors might be a predictive parameter of prognosis after radiation therapy for PALN of very advanced uterine cervical carcinoma patients.

Adult↗

PubMedDate not supplied

Oxygenated and reoxygenated tumors show better local control in radiation therapy for cervical cancer.

The presence of hypoxic cells is one of the major factors affecting resistance against radiation therapy. In the clinical setting, little information exists as to the relationship between intratumoral oxygen partial pressure (pO(2)) and outcome. This study involved 30 consecutive patients with cervical cancer, who were treated with a combination of external and high-dose rate intracavitary irradiation. The pO(2) was measured before radiation therapy and at 9 Gy, using a needle-type polarographic oxygen electrode. The mean intratumoral pO(2) before radiation therapy was 17.3 +/- 10.8 mm Hg. The 3-year local control rates of patients with pO(2)< or = 20 mm Hg and pO(2) > 20 mm Hg before radiation therapy were 52% and 100%, respectively, representing a significant difference (P= 0.035). At 9 Gy, mean intratumoral pO(2) was 23.6 +/- 9.1 mm Hg, a significant increase compared to the value before radiation therapy (P= 0.006). The 3-year local control rates of tumors with pO(2)< or = 20 mm Hg and pO(2) > 20 mm Hg at 9 Gy were 35% and 93%, respectively, representing a significant difference (P= 0.001). The significantly better local control for oxygenated tumors at 9 Gy as well as before radiation therapy indicated that the oxygen effect and reoxygenation by radiation played an important role in local control in radiation therapy for cervical cancer.

Adenocarcinoma↗

PubMedDate not supplied

Activin and follistatin as local regulators in the human ovary.

There is increasing evidence that activin may act as an autocrine/paracrine regulator of ovarian functions. Activin subunit mRNAs as well as activin immunoreactivities have been detected in the human ovary. Activin alters granulosa cell proliferation and steroidogenesis. The effect of activin is most likely mediated through specific receptors as mRNAs encoding several forms of activin receptors, namely ActR-I, ActR-IB, ActR-II and ActR-IIB are found in the preovulatory follicles as well as in cultured granulosa-luteal cells. Activin-binding protein, follistatin (FS), is also produced in the human ovary. In addition to neutralizing the effect of activin on steroid production, FS on its own also enhances estradiol production, an effect similar to that seen after activin treatment. These findings strongly suggest that activin and FS are important local regulators of steroidogenesis in the human ovary.

Activin Receptors↗

PubMedDate not supplied

Appearance of primary endometrial and ovarian clear cell adenocarcinoma 17 months postpartum. A case report.

BACKGROUND: Rare cases of endometrial cancer have been reported within two years postpartum. However, clear cell adenocarcinoma of the endometrium does not appear to have been reported before as occurring in the early postpartum period. CASE: A 33-year-old-female experienced abnormal uterine bleeding 17 months after the delivery of her second child by cesarean section. Computed tomography indicated the presence of tumors in the uterus and cul-de-sac. Preoperative evaluation of endometrial cytology revealed adenocarcinoma cells. These cells demonstrated a centrally located nucleus and translucent, clear cytoplasm, with the so-called mirror ball pattern of cell clusters. The cytologic diagnosis was clear cell adenocarcinoma. Postoperative histologic evaluation verified the presence of a solid type of clear cell adenocarcinoma. The patient was considered to have simultaneous primary clear cell adenocarcinoma of the endometrium and ovary. CONCLUSION: Preoperative endometrial cytology correctly suggested the histologic type of cancer.

Adenocarcinoma, Clear Cell↗

PubMedDate not supplied

Effects of orally administered 5-fluorouracil and its derivative 5'-deoxy-5-fluorouridine on 7,12-dimethylbenz[a]anthracene-induced breast carcinomas in rats.

Antitumour activity of 20 mg/kg 5-fluorouracil (5-FU) and 100 or 200 mg/kg 5'-deoxy-5-fluorouridine (5'-DFUR) was assessed by tumour regression, light and electron microscopic changes, and immunohistochemical variations in broxuridine labelling in 7,12-dimethyl-benz[a]anthracene- (DMBA-) induced breast carcinomas in rats. The relative regression of tumours was significantly (P less than 0.05) greater in animals receiving 5-FU or 5'-DFUR than in control animals. Light microscopic changes became apparent after 3 or 4 days' treatment and were more evident after 4-21 days. Electron microscopic degeneration of tumours was observed after 1 day. The broxuridine labelling index decreased significantly (P less than 0.05) in rats receiving 5-FU and especially in those receiving 5'-DFUR. Concentrations of 5-FU in DMBA-induced breast carcinomas were significantly (P less than 0.05) higher in rats treated with 5'-DFUR than in those treated with 5-FU, and the histological degeneration was significantly (P less than 0.05) more advanced in 5'-DFUR- than in 5-FU-treated animals, possibly due to the higher pyrimidine nucleoside phosphorylase activity in the former treatment group.

9,10-Dimethyl-1,2-benzanthracene↗