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Biomedical subjects

A Sueoka

Publications and source records attributed to A Sueoka.

At least 19 recordsLinked to original sources
PubMed2000

In vitro evaluation study of the membrane autotransfusion system experimental prototype: MATS-I.

Membrane Autotransfusion System (MATS) utilizing plasmapheresis technology has been developed in our laboratory. A specially designed polyethylene hollow fiber membrane was utilized. This study was conducted to evaluate performance of the first experimental prototype, MATS-I. The results of this study showed that the MATS-I could concentrate diluted blood at 10% of the initial hematocrit concentration (HCTi) into over 40% after passing through the system at a transmembrane pressure of 70 mm Hg. Moreover, the MATS-I can continuously treat 10,000 ml of diluted blood at various HCTi levels without deteriorating its performances. Even though the MATS-I met all required performances as an autotransfusion system, several areas of improvement of the system were necessary to meet various clinical needs. The next prototype, MATS-II, can be designed based on experiences obtained from the MATS-I. The MATS is smaller, more atraumatic and continuous, and is a faster system when compared to the currently available centrifugal autotransfusion devices.

Animals↗
PubMed2000

Development of the membrane autotransfusion system prototype-II: MATS-II.

This article is the second of a two-part series describing a membrane autotransfusion system, MATS, utilizing plasmapheresis technology. Based on experiences obtained from the first prototype (MATS-I), optimum blood filtration parameters with refined blood and flux pump synchronization were put into an original CPU-board and loaded on a miniaturized, self-operative, and preclinical prototype (MATS-II). This study was conducted to evaluate the MATS-II using diluted blood of various hematocrit concentrations. The results proved that this device could concentrate 4,000-10,000 ml of various hematocrit concentrations into higher than 40% while automatically controlling the flow speed from 250 to 400 ml/min. Also, no significant damage was generated to the red blood cells (RBC). Moreover, the MATS-II salvaged over 90% of platelets together with the RBC. These results suggest that the MATS-II achieves all clinical requirements of an autotransfusion device; it is a continuous hemoconcentration device with minimum damage to cellular components of the blood.

Animals↗
PubMed2000

Therapeutic apheresis application using membrane plasma fractionation technology: present scope and limitations.

Membrane technologies have been applied for therapeutic apheresis, such as plasma separation and plasma fractionation. Membrane used for plasma fractionation has a microporous structure with pore sizes in the range of 0.01-0.04 microm. A membrane plasma fractionator is utilized for the second filter in the double filtration plasmapheresis (DFPP) system and is applied for treatment of various diseases. This article summarizes the present scope and limitation of membrane plasma fractionation.

Chemical Fractionation↗
PubMed1999

In vitro comparison study of CD63 and CD62P expression after contacting leukocyte filters.

CD63 and CD62P have been recognized as platelet activation markers. This study investigated the secretion of these antigens to compare the platelet activation between a newly developed stainless steel leukocyte filter (SSLF) and 7 polyester or polyurethane commercially available leukocyte filters. Flow cytometry demonstrated that the SSLF initiated significantly smaller effects in terms of mean fluorescence intensity of CD63 (p<0.03) and of the amount of CD62P expressing platelets (p<0.002) compared to the polyurethane filters. However, there was no statistical difference between the SSLF and polyester filters. The result of this study suggests that the SSLF caused less platelet activation than the polyurethane filters and has biocompatible characteristics comparable to the currently available polyester filters. Stainless steel was selected because of its physicochemical conductivity. With these results, further evaluation of the SSLF will be continued in an attempt to develop an active immunomodulator using this unique characteristic.

Adult↗
PubMed1999

Long-term in vivo left ventricular assist device study for 284 days with Gyro PI pump.

A totally implantable centrifugal artificial heart has been developed. The plastic prototype, the Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart (TAH), 2 week screening tests for anti-thrombogenecity, and a 1 month system feasibility study. Based upon these results, a metallic prototype, the Gyro PI 700 series, was subjected to long-term in vivo left ventricular assist device (LVAD) studies of over 1 month. The Gyro PI 700 series has the same inner dimension and same characteristics of the Gyro PI 601 such as an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI metallic pump is also driven with the Vienna DC brushless motor actuator like the PI 601. The pump-actuator package was implanted in 3 calves in the preperitoneal space, bypassing from the left ventricular (LV) apex to the descending aorta. Case 1 achieved a 284 day survival. Case 2 was euthanized early at 72 postoperative days as a result of the functional obstruction of the inlet port due to the excessive growth of the calf. There was no blood clot inside the pumps of either case. Case 3 is on-going (22 days on July 24, 1998). During these periods, all cases showed no physiological abnormalities. In conclusion, the PI 700 series pump has excellent results as a long-term implantable LVAD.

Animals↗
PubMed1999

An emergency balloon occlusion system for a rotary blood pump left ventricular assist system.

A fatal outcome is expected in a left ventricular assist system (LVAS) utilizing a rotary blood pump if there is no mechanism to prevent the backflow from the aorta to the heart in the case of acute pump failure. To solve this problem, a passive mechanical clamping system at the outflow graft of a rotary blood pump was developed together with Fuji Systems, Inc., Yokohama, Japan. The system consisted of an emergency clamp port and an occlusion balloon. The balloon was fixed around the outlet graft of the LVAS. In an in vitro study, a fail-safe clamping operation with 2 ml saline injection under 7 L/min flow against 140 mm Hg pressure reduced the flow to 0.5 L/min while the pressure in the system increased to 190 mm Hg. The systems were also applied to 2 in vivo LVAD studies. When the pumps were stopped, there were approximately 3.0 L/min regurgitant flows. The balloon occluder prevented this regurgitant flow effectively against a 100/80 mm Hg arterial pressure. In conclusion, this emergency balloon occlusion system is relatively easy to operate and will work efficiently in all possible clinically encountered malfunctions of the rotary blood pump LVAS.

Animals↗
PubMed1999

Preliminary evaluation study of a prototype hollow fiber membrane for the continuous membrane autotransfusion system.

A totally new autotransfusion system has been developed utilizing a hollow fiber membrane, based upon plasmapheresis technology. Prior to fabricating the system, it was essential to evaluate the basic performance characteristics of the filter, which was designed particularly for the new system. The objective of this study was to prove or disprove that such a system would be available using this filter. An in vitro study was conducted on the filter using bovine blood. The result of the study showed that the filter could process 2-20% of hematocrit blood at a flow rate greater than 250 ml/min of inlet blood continuously. Moreover, it could concentrate 5-20% hematocrit blood to hematocrit percentages greater than 40% by a single passage through the filter. These results seemed to prove that a rapid, continuous, and compact autotransfusion system could be developed using this filter.

Blood Transfusion, Autologous↗
PubMed1998

Evaluation of platelet adhesion and activation on materials for an implantable centrifugal blood pump.

A totally implantable centrifugal artificial heart has been developed in which a pivot bearing supported centrifugal pump is used as a blood pump. The following have been adopted as blood contacting materials in our pump: titanium alloy (Ti-6A1-4V) for the housing and impeller, alumina ceramic (Al2O3) for the male pivots, and ultrahigh molecular weight polyethylene (PE) for the female pivots. Greater antithrombogenicity is required for an implantable blood pump. To examine the thrombogenicity of these materials, we evaluated in vitro platelet adhesion and activation, which may play key roles in thrombogenesis on foreign surfaces. Ti-6A1-4V, Al2O3, and PE were compared with polycarbonate (PC), silicone carbide (SiC), and pure titanium (pTi). Platelet adhesion was assessed using monoclonal antibody (CD61) directed against glycoprotein IIIa. Platelet activation was evaluated by measuring P-selectin (GMP-140) released from irreversibly activated platelets. Each material with a surface area of 16.6 cm2 was incubated with 2.5 ml of plasma or 2.5 ml of heparinized fresh whole blood for 3 h at 37 degrees C. The optical density (OD) at a wavelength of 450 nm for CD61 was 0.93+/-0.35 in PC, 0.34+/-0.13 in PE, 0.27+/-0.13 in pTi, 0.26+/-0.01 in Al2O3, 0.21+/-0.04 in SiC, and 0.12+/-0.12 in Ti-6A1-4V. The GMP-140 levels of the tested materials were not significantly different from the control value (45.9+/-7.2 ng/ml). These results indicate that Al2O3, PE, and Ti-6A1-4V, which are incorporated into our implantable centrifugal pump, have satisfactory antithrombogenic properties in terms of platelet adhesion. However, platelet activation by any material was not observed under the static condition in this study.

Alloys↗
PubMed1998

Present status of apheresis technologies: part 4. Leukocyte filter.

This article is the fourth of a 4 part series describing the currently available apheresis devices and technologies. The sections include the following: Part 1, Membrane Plasma Separator (published in Vol. 1, No. 1); Part 2, Membrane Plasma Fractionator (published in Vol. 1, No. 2); Part 3, Adsorbent (published in Vol. 1, No. 3); and Part 4, Leukocyte Filter.

Autoimmune Diseases↗
PubMed1998

Current therapeutic apheresis technologies for inflammatory bowel disease.

A large number of physicians have indicated that patients with inflammatory bowel diseases (IBD) such as ulcerative colitis (UC) and Crohn's disease (CD) respond to current apheresis technology treatment. However, the mechanism of the apheresis procedure is undefined for patients with IBD. IBD appears to be caused by a complex of interactions from the genes, environment, and the immune system; therefore, the immune system plays a crucial role in the inflammatory responses. In this process, lots of interactions occur simultaneously, and they cross relate with each other. This review paper briefly discusses the etiology and pathogenesis of IBD and attempts to elucidate the mechanism that occurs after apheresis treatment.

Blood Component Removal↗
PubMed1998

Applications of membrane technologies for therapeutic apheresis.

Membrane technologies have been applied for therapeutic apheresis. Membrane plasma separation and plasma fractionation are the most common, and hemodialysis and hemofiltration are also used for the combination methodologies of plasma exchange. This article describes the structure, performance, and application of membranes used for apheresis.

Blood Component Removal↗
PubMed1997

Effects of ultrathin silicone coating of porous membrane on gas transfer and hemolytic performance.

To assess the effect of an ultrathin (0.2 microm) silicone-coated microporous membrane oxygenator on gas transfer and hemolytic performance, a silicone-coated capillary membrane oxygenator (Mera HP Excelung-prime, HPO-20H-C, Senko Medical Instrument Mfg. Co., Ltd., Tokyo, Japan) was compared with a noncoated polypropylene microporous membrane oxygenator of the same model and manufacturer using an in vitro test circuit. The 2 oxygenators showed little difference in the oxygen (O2) transfer rate over a wide range of blood flow rates (1 L/min to 8 L/min). The carbon dioxide (CO2) transfer rate was almost the same in both devices at low blood flow rates, but the silicone-coated oxygenator showed a decrease of more than 20% in the CO2 transfer rate at higher blood flow rates. This loss in performance could be partly attenuated by increasing the gas/blood flow ratio from 0.5 or 1.0 to 2.0. In the hemolysis study, the silicone-coated membrane oxygenator showed a smaller increase in plasma free hemoglobin than the noncoated oxygenator. The pressure drop across both oxygenators was the same. These results suggest that the ultrathin silicone-coated porous membrane oxygenator may be a useful tool for long-term extracorporeal lung support while maintaining a sufficient gas transfer rate and causing less blood component damage.

Adult↗
PubMed1997

Anatomical consideration for an implantable centrifugal biventricular assist system.

A miniaturized pivot bearing-supported centrifugal blood pump (Gyro PI) has been developed as a long-term biventricular assist system (BiVAS). In this study we determined the anatomical configuration of this system using a bovine model. Under general anesthesia, a left lateral thoracotomy was performed to open the chest. Two Gyro PI-601 pumps for left and right assists were placed in the preperitoneal pocket by a subcostal abdominal incision. The left pump could be placed along the dome of the diaphragm just beneath the apex of the left ventricle. The right pump could be placed next to the left pump. The inlet and outlet ports of both pumps penetrated the diaphragm. The inlet port of the left pump, with a length of 55 mm, was inserted directly into the apex of the left ventricle. A woven Dacron graft (150 mm long, 11 mm inner diameter) was placed between the outlet port of the left pump and the descending aorta. As for the right pump, a 100 mm long and 120 degree angled inflow conduit was placed between the inlet port and the right ventricular infundibulum. The outlet port of the right pump was connected to the main trunk of the pulmonary artery using a 90 mm long, 11 mm inner diameter Dacron graft. We could perform biventricular assistance to confirm the anatomical feasibility of the Gyro implantable centrifugal BiVAS.

Animals↗
PubMed1997

Development and initial testing of a permanently implantable centrifugal pump.

To be able to salvage heart failure patients, the need for an economical permanent ventricular assist device is increasing. To meet this increasing demand, a miniaturized centrifugal blood pump has been developed as a permanently implantable device. The Gyro permanently implantable model (PI-601) incorporates a sealless design with a blood stagnation free structure. The pump impeller is magnetically coupled to the driver magnet in a sealless manner. This pump is atraumatic and antithrombogenic and incorporates a double pivot bearing system. A miniaturized actuator was utilized in this system in collaboration with the University of Vienna. The priming volume of this pump is 20 ml. The overall size of the pump actuator package is 53 mm in height and 65 mm in diameter, 145 ml of displacement volume, and 305 g in weight. Testing to date has included in vitro hydraulic performance and hemolysis. This pump can provide 5 L/min against a 110 mm Hg total pressure head at 2,000 rpm and 8 L/min against 150 mm Hg at 2,500 rpm. The normalized index of hemolysis (NIH) value of this pump was 0.0028 g/100 L at 5 L/min against 100 mm Hg. A preliminary anatomical study revealed the possibility of the implantability of 2 such systems in biventricular bypass at a preperitoneal location. This system is feasible for use as a permanently implantable biventricular assist device.

Animals↗
PubMed1997

Membrane apheresis technology: historical perspective and new trends toward bioincompatible systems.

During the past 25 years, membrane apheresis technology has been well developed through the use of biocompatible devices and immunomodulation. Now, however, we must move into a new era reconsidering the concepts of apheresis technology and considering the urgent need to develop a bioincompatible apheresis system. In the past, our aim in this field was to develop the best blood compatible system possible. With these systems, best efforts were made to reduce procedurally induced immunomodulation effects. However, it is these authors' opinion that procedurally induced immunomodulation effects should be augmented rather than reduced by incorporating such a bioincompatible apheresis system. Augmented immunoactivation and immunosuppression introduced by such systems should add therapeutic effects to the apheresis procedures. Therefore, we anticipate that the current marginally effective diseases may benefit from this strategic change in apheresis procedures.

Antibody Formation↗