Biomedical subjects

T Takano

Publications and source records attributed to T Takano.

790 records · Page 44Linked to original sources

PubMedDate not supplied

Initial clinical trial of a closed loop, fully automatic intra-aortic balloon pump.

A new generation, closed loop, fully automatic intraaortic balloon pump (CL-IABP) system continuously optimizes diastolic augmentation by adjusting balloon pump parameters beat by beat without operator intervention. In dogs in sinus rhythm and with experimentally induced arrhythmias, the new CL-IABP system provided safe, effective augmentation. To investigate the system's suitability for clinical use, 10 patients meeting standard indications for IABP were studied. The patients were pumped by the fully automatic IABP system for an average of 20 hr (range, 1-48 hr). At start-up, the system optimized pumping parameters within 7-20 sec. Evaluation of 186 recordings made at hourly intervals showed that inflation began within 20 msec of the dicrotic notch 99% of the time. In 100% of the recordings, deflation straddled the first half of ventricular ejection. Peak pressure across the balloon membrane averaged 55 mmHg and, in no case, exceeded 100 mmHg. Examination of the data showed that as soon as the system was actuated it provided consistently beneficial diastolic augmentation without any further operator intervention. Eight patients improved and two died (one of irreversible cardiogenic shock and one of ischemic cardiomyopathy). No complications were attributable to the investigational aspects of the system. A fully automated IABP is feasible in the clinical setting, and it may have advantages relative to current generation IABP systems.

Adult↗

PubMedDate not supplied

Long-term in vivo left ventricular assist device study with a titanium centrifugal pump.

A totally implantable centrifugal artificial heart has been developed. The plastic prototype, Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart, 2 week screening tests for antithrombogenicity, and 1 month system feasibility. Based on these results, a metallic prototype, Gyro PI 702, was subjected to in vivo left ventricular assist device (LVAD) studies. The pump system employed the Gyro PI 702, which has the same inner dimensions and the same characteristics as the Gyro PI 601, including an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI 702 is driven with the Vienna DC brushless motor actuator. For the in vivo LVAD study, the pump actuator package was implanted in the preperitoneal space in two calves, from the left ventricular apex to the descending aorta. Case 1 achieved greater than 9 month survival without any complications, at an average flow rate of 6.6 L/min with 10.2 W input power. Case 2 was killed early due to the excessive growth of the calf, which caused functional obstruction of the inlet port. There was no blood clot inside the pump. During these periods, neither case exhibited any physiologic abnormalities. The PI 702 pump gives excellent results as a long-term implantable LVAD.

Equipment Design↗

PubMedDate not supplied

Development of an antithrombogenic and antitraumatic blood pump: the Gyro C1E3.

The Gyro C1E3 is a centrifugal blood pump. Its antithrombogenic and antitraumatic blood features were demonstrated by prior studies. Based upon these studies, a mass production model of the C1E3 is becoming commercially available. Therefore, this feasibility study was conducted using the mass production models of the Gyro C1E3 for long-term cardiac assist in ex vivo animal experiments. Five healthy calves were used and 15 pump heads were applied for different time periods (Group 1, 30 days; Group 2, 14 days; Group 3, 10 and 7 days; Group 4, 4 days; and Group 5, 2 days). Activated clotting time (ACT) was kept at 200-250 sec. All five calves demonstrated neither abnormal signs nor abnormal blood examination data throughout the experiment. During necropsy, no thromboembolism was found in any downstream organs. Groups 1-4 showed thrombi inside the pump heads while two pumps in Group 5 had no thrombi formations. Bearing deformation or possible wear did not increase after 2 days of pumping. The C1E3 is capable of long-term assist circulation. However, after 2 days of pumping, careful observation is necessary since thrombi may occur inside the pump when ACT is controlled under 250 sec. During the weaning stage or low flow (under 2 L/min), over 250 sec of ACT is recommended to assure the safety of the patient.

Animals↗

PubMedDate not supplied

Development of an implantable small right ventricular assist device.

Currently, at least two permanent implantable left ventricular assist devices (LVADs) are used clinically. Unfortunately, there is no small implantable right ventricular assist device (RVAD) available, even though at least 25-30% of this patient population has right ventricular failure. If a small implantable RVAD were available, biventricular assist could support patients with right ventricular failure. A small atraumatic and antithrombogenic RVAD is being developed to meet this clinical need. This small centrifugal blood pump, the Gyro PI pump, is 6.5 cm in diameter and 4.6 cm in height and has three unique characteristics to prevent thrombus formation: (1) the double pivot bearing and magnetic coupling system enable this pump to be completely sealless; (2) the secondary vanes at the bottom of the impeller accelerate the blood flow and prevent blood stagnation; and (3) the eccentric inlet port enables the top female bearing to be embedded into the top housing and decrease blood cell trauma. The inflow conduit consists of a wire reinforced tube and a hat-shaped tip that is biolized with gelatin to create a thrombus resistant material. This conduit is directly implanted into the right ventricle, and the outflow conduit is anastomosed to the PA. The pump can be implanted inside the abdominal wall or in the thoracic cavity. Biocompatibility of this pump was proved in two calves by thrombus free implantation as an LVAD for 284 days and 200 days. Two RVAD implantations were conducted, aiming for 1-month system feasibility studies. During the month, the RVADs operated satisfactorily without any thromboembolic incident. No blood clots or abnormal findings were seen inside the pump, nor were there abnormal findings in the explanted lungs except for small areas of atelectasis. The pump flow was 3.02 +/- 0.38 L/min in calf 1 and 3.75 +/- 1.18 L/min in calf 2. The power requirement was 7.28 +/- 0.43W for calf 1 and 14.52 +/- 3.93W for calf 2. The PaO2 was 72.0 +/- 3.60 mm Hg (calf 1) and 72.0 +/- 7.63 mm Hg (calf 2); PaCO2 was 38.3 +/- 2.17 mm Hg (calf 1) and 34.1 +/- 1.95 mm Hg (calf 2); and SaO2 was 94.1 +/- 1.37% (calf1) and 95.0 +/- 1.95% (calf 2). Gas exchange via the lungs was maintained. These studies indicate that the Gyro PI pump is suitable as a single implantable RVAD, and is a feasible RVAD as a part of a BiVAD system in terms of pump performance and thrombus resistance.

Animals↗

PubMedDate not supplied

Preclinical evaluation of a hollow fiber silicone membrane oxygenator for extracorporeal membrane oxygenator application.

A silicone membrane hollow fiber oxygenator applicable for use as an extracorporeal membrane oxygenator (ECMO) has been developed in our laboratory. This silicone hollow fiber displays astonishing mechanical stability, is barely compressible or stretchable, and assembles easily while maintaining good gas permeability. The priming volume is 140 cc with a surface area of 0.8 m2. This study evaluated the gas transfer performances and biocompatibility of the oxygenator under ECMO and CPB conditions. In vitro studies that were performed at a blood flow rate of 2 L/min, and revealed O2 and CO2 gas transfer rates of 82.35 +/- 0.56 ml/m2/L/min and 38.72 +/- 2.88 ml/m2/L/min, respectively. The commercially available Kolobow (Avecor 1500) oxygenator was used as the control, and had O2 and CO2 gas transfer rates of 53.8 +/- 0.5 ml/m2/L/min and 24.7 +/- 2.0 ml/m2/L/min. To evaluate blood trauma, Normalized Index of Hemolysis (NIH) was measured according to American Society of Testing and Materials (ASTM) standards. The NIH findings were 0.0112 g/100L at a blood flow of 1 L/min, and 0.0152 g/100L at 5 L/min. Three ex vivo experiments, using a blood flow rate of 1 L/min, were performed with venoarterial bypass, and O2 transfer rate and CO2 transfer rate of the oxygenators were well maintained. This indicates that this preclinical silicone membrane hollow fiber oxygenator has superior efficiency, less blood trauma, and is smaller when compared with the only clinically available Kolobow oxygenator.

Animals↗

PubMedDate not supplied

Blood trauma induced by clinically accepted oxygenators.

Hemolysis remains one of the most serious problems during cardiopulmonary bypass (CPB), extracorporeal membrane oxygenation (ECMO), and percutaneous cardiopulmonary support (PCPS). However, the hemolytic characteristics associated with oxygenators are not well defined. A specialized hemolysis test protocol for oxygenators was developed. A comparative study was performed following this protocol to determine the hemolytic characteristics of the clinically available oxygenators during CPB; pressure drop measurements in the blood chamber were also performed. Four oxygenators (Medtronic Affinity, Cobe Optima, Terumo Capiox SX25, and Bard Quantum) were evaluated. Fresh blood from healthy Dexter calves anticoagulated with citrate phosphate dextrose adenine solution was used. The blood flow was fixed at 5 L/min, similar to that used in CPB. The Normalized Index of Hemolysis for Oxygenators (NIHO) has been modified according to the American Society of Testing and Materials (ASTM) standards. The NIH value, which was obtained from the circuit without an oxygenator, was subtracted from the primary NIH value, obtained from the circuit with an oxygenator to eliminate the effects of a centrifugal pump or other artifacts. The NIHO value was the lowest in the Affinity (0.0116 +/- 0.0017) and increased from Affinity < Optima (0.0270 +/- 0.0038) < Capiox (0.0335 +/- 0.0028) < Quantum (0.0416 +/- 0.0015 g/100 L). The Optima and Capiox did not demonstrate a significant difference. In addition, this NIHO value has a close relationship to the pressure drop. In conclusion, this new evaluation method is suitable to compare the biocompatibility performance of different types of clinically available oxygenators for CPB usage.

Animals↗

PubMedDate not supplied

Direct detection of red blood cell fragments: a new flow cytometric method to evaluate hemolysis in blood pumps.

Pump induced hemolysis is presently evaluated by measuring plasma free hemoglobin (fHb). However, this method has disadvantages because quantification of fHb depends on hematocrit (HCT) and hemoglobin (Hb) levels. The aim of this work was to devise a hemoglobin independent method, capable of quantifying cell trauma directly by measuring the number of red blood cell (RBC) fragments. Whole blood flow cytometry was used to quantify circulating RBC fragments derived from a roller pump (Sarns, Inc. Model 2 M 6,002) and a centrifugal pump (Gyro C1E3, Kyocera Corp.). The pumps were tested in a mock circuit for 2 hr (5 L/min flow against 100 mm Hg pressure head). Red blood cell fragments were quantified by a phycoerythrin (PE) labeled glycophorin A antibody specific for erythrocytes. Red blood cell fragments were smaller than the intact RBC population and overlapped in size with the platelet population (based on forward- and side-light scattering measurements). For the roller pump, the values for RBC fragments increased from 1,090 +/- 260/microl at 0 min to 14,880 +/- 5,900/microl after 120 min. In contrast, using the centrifugal pump, there was little increase in RBC fragments (from 730 +/- 270/microl at 0 min to 1,400 +/- 840/microl after 120 min). Flow cytometry can be used for the rapid, sensitive, hemoglobin independent evaluation of pump induced RBC trauma.

Erythrocytes↗

PubMedDate not supplied

MR arteriography using an implantable port system: a new method in assessing perfusion abnormalities during hepatic arterial infusion chemotherapy.

We present a case in which MR arteriography (MRA) with an indwelling catheter was used in a perfusion study of intrahepatic arterial chemotherapy for liver metastases. After embolization of collateral vessels using platinum coils, CT imaging was disturbed by strong artifact. However, platinum coils produced no MR artifact. In addition, MRA had greater advantages in depicting perfusion defects than perfusion scintigraphy. We consider MRA useful in assessing perfusion abnormalities during intrahepatic arterial chemotherapy.

Antineoplastic Agents↗

PubMedDate not supplied

Operating point control system for a continuous flow artificial heart: in vitro study.

We proposed and developed a practical and effective servo control system for rotary blood pumps. A rotary blood pump for assisting the failing natural heart should be operated only in physiologically acceptable conditions. The operation of a rotary blood pump is based on the rotational speed of the impeller and pressure head. If the pump flow and the pressure head are set within an acceptable range, the driving condition is deemed normal condition, and this control system maintains the preset operating point by applying proportional and detective control (PD control). If the pump flow or pressure head is outside the acceptable range, the driving condition is determined to be abnormal condition, and this system operates the pump in a recovery fashion. If the driving condition is kept under abnormal conditions of sudden decrease of the flow, the condition is termed a suction condition. The controller releases the pump from the suction condition and later returns it to the normal condition. In this study, we evaluated these servo control modes of the centrifugal pump and confirmed whether the performance of this proposed operating point control system was practical.

Algorithms↗

PubMedDate not supplied

Primary ependymoma of the ovary: a case report and literature review.

Ependymoma is a glioma with differentiation toward ependymal cells that usually arises in the central nervous system. Ovarian ependymoma is extremely rare, and the treatment strategies for this disease have not been established. This is the first report of a patient with advanced ovarian ependymoma who received fertility-sparing surgery and is now alive without disease. A 23-year-old Japanese woman, gravida 0, presented with a chief complaint of lower abdominal distension and weight loss. She underwent left salpingo-oophorectomy for suspected ovarian cancer. Microscopic examination revealed a highly cellular tumor composed of small cells with hyperchromatic, round-to-oval nuclei and scanty cytoplasm. Perivascular pseudorosettes, ependymal rosettes, and extensive necrosis were observed. After thorough pathologic examination, she was diagnosed as having stage IIIC ovarian ependymoma. Postoperatively, she received adjuvant chemotherapy and underwent secondary cytoreductive surgery that preserved the uterus and right ovary. Her menstrual cycle has resumed, and she is alive without evidence of disease 16 months after the start of treatment. Although rare, primary ovarian ependymoma must be kept in mind in the differential diagnosis of ovarian tumors, especially in young women. Administration of etoposide-based chemotherapy along with cytoreductive surgery is a potential standard treatment for advanced ovarian ependymoma.

Adult↗

PubMedDate not supplied

Paget's disease of the vulva: clinicopathologic study of type 1 cases treated at a single institution.

The aim of this study was to evaluate clinicopathologic characteristics of primary cutaneous Paget's disease of the vulva. Between 1986 and 2005, 22 patients with primary cutaneous Paget's disease of the vulva (type 1) were treated at Tohoku University Hospital. Medical records were reviewed for pathologic diagnosis, patient age, associated neoplasms, type(s) of eczema, symptom duration, treatment, surgical procedures, recurrence, and length of follow-up. Patient age ranged from 51 to 85 years (median 71.5 years). Median duration of symptoms was 24 months (range 2-60 months). Type 1a (intraepithelial) Paget's disease accounted for 18 patients, with 3 type 1b (invasive) cases and 1 type 1c (intraepithelial disease with underlying adenocarcinoma) case. Mean length of follow-up was 53.7 months, and median follow-up was 49 months (range 6-199 months). Only two patients had an associated internal malignancy: T-cell leukemia and breast cancer. Mapping biopsy was performed in 14 of the 18 type 1a cases. All patients were free of disease at the surgical margins and are alive without recurrence. The four patients with type 1b or 1c disease had lymph node metastases. Two has died of disease, and two are alive with no recurrence. The rate of secondary malignancy seems to be low in primary cutaneous Paget's disease of the vulva. Mapping biopsy with careful examination of characteristic skin surface may be useful for surgery of type 1a cases. Inguinal lymphadenectomy is recommended in cases with question of invasion or known underlying adenocarcinoma.

Adenocarcinoma↗

PubMedDate not supplied

Generalized seizure triggering threshold and serum phenobarbital levels during pregnancy in rats.

In experiments using pregnant rats, the following results were noted: (a) Of the amygdaloid kindled rats, the generalized seizure triggering threshold of the pregnant group was significantly higher than that of the nonpregnant group. (b) Of the rats taking oral phenobarbital, 4 mg/kg once a day, there was no significant difference of serum levels between the pregnant group and the nonpregnant group. (c) Of the amygdaloid kindled rats taking oral phenobarbital, 4 mg/kg once a day, the generalized seizure triggering threshold of the pregnant group was significantly higher than that of the nonpregnant group. It may be suggested that, when the drug dose remains the same, the rise in threshold by gestational physiological changes antagonizes the fall in threshold by decreased serum levels of anticonvulsants because of increasing distribution volume due to increasing body weight during pregnancy.

Animals↗

PubMedDate not supplied

Effect of small deep hemispheric infarction on the ipsilateral cortical blood flow in man.

The effect of small, deep ischemic lesions on the ipsilateral cortical circulation was investigated in 10 patients with persistent mild or moderate neurological deficits due to infarcts in the internal capsule. rCBF studies by the 133Xe intracarotid injection method were performed 14-180 days after the onset of the infarction. The rCBF functional image was made up from the data of 133Xe dynamic images measured by an Anger-type gamma camera and the rCBF values were calculated by the initial slope method. The average value of mean rCBFs (mCBF) in 10 patients was 44.9 +/- 7.1 ml/100g/min (average PaCO2; 39.9 +/- 4.3 mm Hg). In the rCBF functional images, a focal hypoperfusion area was observed in all cases and localized around the central sulcus, especially in the precentral and central areas. Significant decreases of mCBF and the tendency to decrease of the rCBFs in the hypoperfusion focus were noted in the patients with the larger infarcts in comparison with those with the smaller ones. These results suggest that a small, deep ischemic lesion such as a capsular infarct may have remote effects on the ipsilateral cortical circulation, due probably to the damage of a number of fibers passing through the lesion.

Adult↗

PubMedDate not supplied

Subclavian steal in Takayasu's arteritis. A hemodynamic study by means of ultrasonic Doppler flowmetry.

Blood flow in the vertebral artery and the upper extremity was studied in five cases of Takayasu's arteritis with subclavian steal by use of ultrasonic Doppler flowmetry and finger plethysmography. The diagnosis of subclavian steal was made by observation of flow reversal in the vertebral artery on the subclavian steal side during grip exercise and, in addition, the vertebral flow change with brachial artery occlusion. The blood flow increase of both internal cartotid and non-affected (non-subclavian steal side) vertebral arteries during a common carotid compression was almost normal in patients with Takayasu's arteritis in this study. During carotid compression on the side of the subclavian steal, ipsilateral vertebral blood flow greatly decreased, and the amplitude the ipsilateral finger plethysmogram decreased slightly or moderately. It is suggested that there are significantly important factors in suppressing sumptoms of vertebrobasilar ischemia in these patients with Takayasu's arteritis with subclavian steal. These factors are believed to be (1) good function of the circle of Willis, (2) good blood supply to the brain stem, and (3) collateral circulation to the distal subclavian artery not via the vertebral artery.

Aortic Arch Syndromes↗

PubMedDate not supplied

Enhanced arrhythmogenicity of Freon 113 by hypoxia in the perfused rat heart.

The interaction of Freon 113 (1,1,2-trichloro-1,2,2-trifluoroethane) and hypoxia on the heart conduction system was studied using electrocardiogram monitoring of isolated perfused rat hearts. Freon 113 (0.2 mM) alone elicited significant atrioventricular conduction delay (p less than 0.05) and heart rate decrease (p less than 0.01), which were significantly enhanced by hypoxia (75% oxygen decrease), for instance, resulting in 2:1 AV block. The data suggest that arrhythmogenicity of Freon 113 on the heart conduction system may be enhanced synergistically by hypoxia.

Animals↗

PubMedDate not supplied

Mobility function of the elderly living with their children and its relation to the home health care system in Tokyo.

Most elderly in Japan prefer living with their children once their spouse passes away. In comparison with western countries, home health care systems have developed quite differently in Japan. The traditional practice of the elderly living with their children is, however, changing. In 1989 we carried out a mail questionnaire survey focused on the relationship between mobility functions of the elderly living in Tokyo and their rate of living with family members. The subjects for the present analysis were 2368 widows and widowers. Under the group category 'independent in long walks', 72.8% were living with their families. With a decrease in mobility functions, this percentage rose to 81.1 and 84.6, although it decreased to 50.9 in the group with severely impaired mobility functions. The need to develop effective social services for families housing their parents is discussed.

Activities of Daily Living↗