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Biomedical subjects

E Okamoto

Publications and source records attributed to E Okamoto.

At least 343 records · Page 19Linked to original sources
PubMedDate not supplied

Registries in Japan: current status of hepatocellular carcinoma in Japan. Liver Cancer Study Group of Japan.

The Liver Cancer Study Group of Japan registered 11,379 patients with hepatocellular carcinoma (HCC) diagnosed from January 1, 1990 to December 31, 1991 in 536 hospitals throughout the country. This nationwide survey revealed the current status of HCC in Japan regarding the epidemiology, clinical characteristics, histopathological features, diagnosis, surgical and conservative treatments, and the outcome. The survival rates of the HCC patients who received hepatic resection, transarterial embolization (TAE), and percutaneous ethanol injection (PEI) were also calculated based on follow-up from January 1, 1987 to December 31, 1991. Three-year and 5-year survival rates of the patients who underwent hepatic resection were 57.5% and 40.8%, respectively, and those of TAE were 19.5% and 8.0%, respectively. Three-year survival rate of the patients with PEI was 53.2%. Cox's multivariate analysis showed that significant prognostic variables after partial hepatectomy were serum alpha-fetoprotein level, tumor size, number of tumors, associated liver cirrhosis, age, surgical curability, and portal involvement.

Adolescent↗
PubMedDate not supplied

Chorea as a presentation of herpes simplex encephalitis relapse.

Three infants, ages 3 months to 3 years, presented with chorea as the initial manifestation of herpes simplex encephalitis (HSE) relapse. Patient 2, treated with repeated 10 day courses of 30 mg/kg/day of acyclovir, had no clear improvement in neurological status. Patient 1, treated with a repeated 10-day course, improved only to have another HSE relapse 4 years later. Patient 3 clearly improved soon after a 3-week course of acyclovir at conventional dosages. A fourth patient (Patient 4) who relapsed with chorea after what was thought to be HSE, and who did not respond to repeated acyclovir treatment, was negative for herpes simplex virus indicators on brain biopsy and DNA testing. We recommend treating all patients suffering from HSE with a minimum 3-week course of acyclovir at 30-35 mg/kg/day in 3 divided doses.

Brain↗
PubMedDate not supplied

Aneurysmal intrahepatic porto-capsular vein anastomosis.

Two cases of intrahepatic porto-capsular vein anastomosis are described, both of which were complicated by liver cirrhosis and hepatocellular carcinoma. In both cases a branch of the portal vein in the posterior segment of the liver was markedly dilated and directly anastomosed at its periphery with the liver's capsular vein, then connected with the inferior vena cava. One of the two cases underwent partial hepatectomy. Histopathological examination of the resected specimen did not reveal any direct relation between the shunt and the carcinoma. The shunting in both cases appeared to have resulted from portal hypertension complicated by liver cirrhosis.

Aneurysm↗
PubMedDate not supplied

Feasibility of a nickel-metal hydride battery for totally implantable artificial hearts.

An implantable rechargeable battery is one of the key technologies for totally implantable artificial hearts. The nickel-metal hydride (Ni-MH) battery is promising for its high energy density of 1.5-2.0 times that of a nickel-cadmium battery. In this study, the effects of pulsatile discharge loads on the operating time and cycle life of Ni-MH batteries at 39 degrees C were studied. Two battery cells (TH-3M, 1,200 mAh, phi 14.5 x 49 mm; Toshiba, Tokyo, Japan) in series were charge/discharge cycled at 39 degrees C using a charge current of 1CA (1,200 mA) and then were fully discharged to 1.0 V/cell under either pulsatile discharge loads, which mimicked a systole (1 A for 0.3 sec) and a diastole (0.4 A for 0.3 sec), or a non pulsatile discharge load equivalent to the average of the pulsatile loads (0.7 A). Each cycle life test was interrupted on the 482nd cycle under pulsatile load, and on the 423rd cycle under non pulsatile load, because of malfunction of each battery charger. The tests showed that the pulsatile discharge cells had significantly (p < 0.001) less operating time (74.0 +/- 7.15 min) throughout the test period (up to 482 days) compared to the cells under equivalent non pulsatile discharge loads (93.7 +/- 7.74 min). The pulsatile-discharged Ni-MH cells provide significantly less operating time than the constantly discharged cells; the Ni-MH battery has an operating time of over 78 min and a cycle life of almost 500 cycles at 39 degrees C. In conclusion, the Ni-MH battery is feasible as an implantable back-up battery for a totally implantable artificial heart system.

Electronics, Medical↗
PubMedDate not supplied

Ferromagnetic artificial cells for artificial circulation.

It is known that deoxygenated blood is paramagnetic. A ferrofluidic actuator for an implantable artificial heart has been studied. The magnetic fluid consists of ferromagnetic magnetite particles (10 nm). If artificial cells encapsulating ferromagnetic particles are mixed in blood, the circulation is maintained by applying a magnetic field to the blood. An array of two poles of ring solenoids with a gap of 10 mm was mounted near the glass tube (7.60 mm inner diameter). The flux density was 0.236 Tesla. Two experiments were conducted using models of artificial cells: 1) the magnetic fluid and 2) the magnetic fluid and an iron cylinder (6.67 mm in diameter and 28.7 mm in length). A flow of 38 to 8 ml/min was obtained against a pressure of 12.5 to 16.3 mmHg in experiment 1, and 80 to 24 ml/min against a pressure of 53 to 240 mmHg in experiment 2. Calculation showed that magnetic fluids could move against a pressure of 100 mmHg if they had a magnetization of 113 kA/m (B = 0.236 Tesla). The magnetic fluid has a magnetization of 35.6 kA/m, whereas the magnetite is 479 kA/m, and that of iron 1398 kA/m. Artificial circulation with ferromagnetic artificial cells could be feasible if artificial cells with a magnetization of 113 kA/m are developed.

Assisted Circulation↗
PubMedDate not supplied

A remote monitoring system for patients with implantable ventricular assist devices with a personal handy phone system.

The usefulness of a remote monitoring system that uses a personal handy phone for artificial heart implanted patients was investigated. The type of handy phone used in this study was a personal handy phone system (PHS), which is a system developed in Japan that uses the NTT (Nippon Telephone and Telegraph, Inc.) telephone network service. The PHS has several advantages: high-speed data transmission, low power output, little electromagnetic interference with medical devices, and easy locating of patients. In our system, patients have a mobile computer (Toshiba, Libretto 50, Kawasaki, Japan) for data transmission control between an implanted controller and a host computer (NEC, PC-9821V16) in the hospital. Information on the motor rotational angle (8 bits) and motor current (8 bits) of the implanted motor driven heart is fed into the mobile computer from the implanted controller (Hitachi, H8/532, Yokohama, Japan) according to 32-bit command codes from the host computer. Motor current and motor rotational angle data from inside the body are framed together by a control code (frame number and parity) for data error checking and correcting at the receiving site, and the data are sent through the PHS connection to the mobile computer. The host computer calculates pump outflow and arterial pressure from the motor rotational angle and motor current values and displays the data in real-time waveforms. The results of this study showed that accurate data on motor rotational angle and current could be transmitted from the subjects while they were walking or driving a car to the host computer at a data transmission rate of 9600 bps. This system is useful for remote monitoring of patients with an implanted artificial heart.

Equipment Design↗
PubMedDate not supplied

A durable, non power consumptive, simple seal for rotary blood pumps.

One of the key technologic requirements for rotary blood pumps is the sealing of the motor shaft. A mechanical seal, a journal bearing, magnetic coupling, and magnetic suspension have been developed, but they have drawbacks such as wear, thrombus formation, and power consumption. A magnetic fluid seal was developed for an axial flow pump. A magnetic fluid seal is durable, simple, and non power consumptive. Long-term experiments and finite element modeling (FEM) analyses confirmed these advantages. The seal body was composed of a Ned-Fe magnet and two pole pieces; the seal was formed by injecting ferrofluid into the gap (50 microm) between the pole pieces and the motor shaft. To contain the ferrofluid in the seal and to minimize the possibility of ferrofluid making contact with blood, a shield with a small cavity was attached to the pole piece. While submerged in blood, the sealing pressure of the seal was measured and found to be 188 mm Hg with ferrofluid LS-40 (saturated magnetization, 24.3 kA/m) at a motor speed of 10,000 rpm and 225 mm Hg under static conditions. The magnetic fluid seals performed perfectly at a pressure of 100 mm Hg for 594 + days in a static condition, and 51, 39+, and 34+ days at a motor speed of 8,000 rpm. FEM analyses indicated a theoretical sealing pressure of 260 mm Hg. The state of the magnetic fluid in the seal in water was observed with a microscope. Neither splashing of magnetic fluid nor mixing of the magnetic fluid and water was observed. The specially designed magnetic fluid seal for keeping liquids out is useful for axial flow blood pumps. The magnetic fluid seal was incorporated into an intracardiac axial flow pump.

Heart-Assist Devices↗
PubMedDate not supplied

Expressions of thymidine phosphorylase (dThdPase) and vascular endothelial growth factor on angiogenesis in intestinal-type gastric carcinoma.

We examined the clinical and pathological significance of thymidine phosphorylase (dThdPase) and vascular endothelial growth factor (VEGF) in human gastric carcinomas, in terms of intratumoral microvessel density (IMVD), P53 expression, and patient prognosis in a total of 128 patients. Mean IMVD was significantly higher in the carcinomas with dThdPase or VEGF expression than in carcinomas without the expression. The simultaneous expression of dThdPase and VEGF was correlated with increased IMVD of human gastric carcinomas. VEGF expression was associated with P53 expression and poor patient prognosis, but dThdPase expression was not.

Adenoma↗
PubMedDate not supplied

Topical cooling assisted hepatic resection of segment 7 and 8 oriented by en-bloc interruption of the targeted portal pedicles.

BACKGROUND/AIMS: The crucial points of hepatic segmentectomy include an accurate mapping of proposed segment(s) to be resected and minimization of intra-operative blood loss. This study reports a surgical technique of hepatic resection for segment 7 and 8, and a benefit of supplemental use of topical cooling during consecutive right hepatic inflow occlusion. METHODOLOGY: From January 1993 to December 1996, ten hepatocellular carcinoma patients with pathologic livers underwent hepatic segmentectomy for segment 7 and 8. The mapping of the target segments was guided by en-bloc test occlusion of the relevant portal pedicles and subsequent discoloration, often after the opening hilum method. Of these, five tumors were resected with topical cooling by ice slush seeding during consecutive right inflow occlusion (cooling group) and the remainder without cooling (Normothermic group). In the normothermic group, inflow occlusion was carried out by cyclic clamping and unclamping method. RESULTS: The inflow occlusion time was 54 +/- 9.4 min in the cooling group, much longer than in the normothermic group. Although the post-operative peak transaminase values were twice as high as those in the normothermic group, the blood loss was significantly less, and there was no detrimental effect of prolonged, consecutive ischemia on the other intra- and post-operative data. CONCLUSIONS: En-bloc taping of the target portal pedicles with or without the opening hilum method is useful in the mapping of segments, and the use of topical cooling is beneficial in prolonged inflow occlusion during complicated right-sided segmentectomy.

Adult↗
PubMedDate not supplied

Radiotherapy of postoperative residual tumor of bile duct carcinoma.

The case of a patient with bile duct carcinoma who had a postoperative residual tumor treated with high-dose-rate intraluminal brachytherapy (HDRIBT) following external radiotherapy is presented. Following radiotherapy, he has been alive and well without signs of recurrence for two years and eleven months as of this writing. HDRIBT following external irradiation is recommended for the treatment of postoperative small residual tumors of the bile duct.

Adenoma, Bile Duct↗
PubMedDate not supplied

High-dose-rate intraluminal brachytherapy for postoperative residual tumor of gallbladder carcinoma: a case report.

The case of a patient with gallbladder carcinoma who had a postoperative residual tumor treated with high-dose-rate intraluminal brachytherapy (HDRIBT) and external radiotherapy (ERT) is presented. HDRIBT (20 Gy/2 fr) was performed at one point 10 mm from the 60Co source on 27 and 34 days after simple cholecystectomy. ERT (30 Gy/15 fr) was also given two weeks after HDRIBT. Following radiotherapy, she has been alive and well without signs of recurrence for one year and ten months as of this writing. HDRIBT combined with ERT is recommended for the treatment of post-operative residual tumors of advanced gallbladder carcinomas.

Adenocarcinoma↗
PubMedDate not supplied

A transcutaneous optical information transmission system for implantable motor-driven artificial hearts.

Precise regulation of output voltage (motor voltage) and monitoring of the implanted pump were obtained with a transcutaneous energy transmission system. Information on both motor voltage and pump stroke is transmitted through the skin by frequency-modulated infrared pulses using a light emitting diode and a phototransistor. The motor voltage is compared with the nominal value, and the duty cycle of the primary pulse is regulated according to the error signal. Infrared pulses up to 100 KHz were transmitted through porcine muscle up to 1 cm thick. Both the pump stroke and motor voltage signals were transferred across the muscle without interference. The output voltage was kept almost constant for the change in tissue gap of 3-8 mm and of 0-10 mm in radial displacement. The system developed is useful for implantable artificial hearts.

Electric Conductivity↗
PubMedDate not supplied

A radical operation for the Budd-Chiari syndrome associated with obstruction of the inferior vena cava. A report of six patients.

The Budd-Chiari syndrome is caused by an occlusion of the hepatic veins and is often associated with an obstruction in the hepatic portion of the inferior vena cava (IVC). Therefore, the various shunt operations done in an attempt to relieve the portal hypertension are often not effective. By using a radical surgical technique on six patients with Budd-Chiari syndrome, the liver was freed and a wide longitudinal incision was made in the hepatic portion of the IVC. The obstructed hepatic vein was reopened using a Fogarty catheter, and a pericardial patch reinforced with a Teflon prosthesis was secured over the incision. Two patients were still asymptomatic 3 and 4 years after operation. Two patients died postoperatively of pneumonia and hepatic insufficiency. The two other patients were discharged in fair condition, and one died 6 months postoperatively following hepatic failure.

Adult↗