Biomedical subjects

T Nakazawa

Publications and source records attributed to T Nakazawa.

At least 181 records · Page 10Linked to original sources

PubMed1997

Yearly and seasonal changes of specific IgE to japanese cedar pollen in a young population.

BACKGROUND: There have been no detailed long-term observations of the relationship between specific IgE production and stimulation by various naturally occurring allergens. OBJECTIVE: This study was conducted to elucidate the yearly and seasonal changes of specific IgE antibody production to Japanese cedar pollen, an allergen of Japanese cedar pollinosis, in young adults. METHODS: The number of Japanese cedar pollen were counted over a period of 9 years. Changes in the percentages of antibody carriers to Japanese cedar pollen and mite were examined during these years. Changes in Japanese cedar pollen-specific IgE levels between a low exposure year and a high exposure year in individual subjects were also investigated. RESULTS: From 1987 to 1995, the percentages of Japanese cedar pollen-IgE carriers varied from about 30% to 50% with the intensity of pollen stimulation, and carriers tended to increase yearly. The rates of anti-mite IgE carriers changed little. In the spring which is the pollen season, Japanese cedar pollen-IgE levels in low exposure years were weaker than those in high exposure years in individual subjects. Levels in autumn, which is not the pollen season, showed equivalent levels in both high and low exposure years. Anti-mite IgE levels in individual subjects varied little during these years. CONCLUSIONS: A long-term follow-up study supported that Japanese cedar pollen-IgE production is mainly associated with the degree of allergen exposure.

Adolescent↗

PubMed1997

Complexity of expression of the intermediate filaments of six new human ovarian carcinoma cell lines: new expression of cytokeratin 20.

Six permanent human ovarian carcinoma cell lines (OVISE, OVTOKO, OVMANA and OVSAYO from clear cell adenocarcinoma, and OVSAHO and OVKATE from serous papillary adenocarcinoma) were established from solid tumours. The cell lines have been in culture for 5-8 years, the passage number varying from 62 to 246. Immunohistochemical analysis has shown that five of the six cell lines express at least six cytokeratin (CK) polypeptides. OVISE and OVSAYO expressed CKs 6, 7, 8, 18, 19 and 15 and/or 16. OVTOKO was positive for CKs 7, 8, 18, 19 and 15 and/or 16. OVSAHO expressed CKs 6, 7, 8, 14, 18, 19 and 15 and/or 16. OVMANA expressed CKs 6, 7, 8, 18, 19, 20 and 15 and/or 16. OVKATE expressed CKs 6, 7, 8, 13, 17, 18, 19, 20 and 15 and/or 16. The expression of CK7, additional expression of vimentin, and clinical and histopathological findings enabled us to confirm that six cell lines had been established from primary ovarian cancers. Two of the six cell lines were positive for CK20, although CK20 was not expressed in the original tumours. The heterotransplanted tumours produced by CK20-positive cells also expressed CK20. This is the first report of ovarian carcinoma cell lines that express CK20 irrespective of their histological type. CK20 has been found in all colon carcinoma cell lines, but only in the mucinous type of ovarian tumours. These new ovarian carcinoma cell lines will therefore provide a relevant experimental system for elucidating the regulatory control mechanisms of intermediate filament expression.

Adenocarcinoma, Clear Cell↗

PubMed1997

Later development of Fas ligand-mediated cytotoxicity as compared with granule-mediated cytotoxicity during the maturation of natural killer cells.

We classified CD56+ CD3- natural killer (NK) cells into CD2- CD56dim (CD2- NK), CD2+ CD56dim (CD2+ NK) and CD2+ CD56bright populations, and investigated mainly functional differences between the former two populations. CD2- and CD2+ NK cells were the same in their morphology and several surface molecules except for CD2. The percentages of CD2- NK cells in total NK cells were higher in the cord blood and marrow than in the peripheral blood of adults or children. Freshly isolated CD2- NK cells had CD2 in the cytoplasm, and gradually expressed it on the surface upon incubation with interleukin-2 (IL-2). These results demonstrated that CD2 is an antigen which appears on the surface during the maturation of NK cells. The granule-mediated cytotoxicities, which are mainly performed by the perforin molecule, of CD2+ NK cells against K562 and Daudi cells were higher than those of CD2- NK cells, and they were inhibited to the levels of CD2- NK cells by the addition of a blocking anti-CD2 monoclonal antibody (mAb). Fas ligand (FasL) mRNA was expressed in freshly isolated CD2+ NK cells but not in the CD2- NK cells. Neither freshly isolated NK populations showed FasL-mediated cytotoxicity, and only CD2+ NK cells lysed Fas-transfected targets after the 24-hr incubation with IL-2. Based on these results, CD2- NK cells have already developed granule-mediated cytotoxicity equal to that of CD2+ NK cells except for the CD2-associated activity, but they, unlike CD2+ NK cells, totally lack FasL-mediated cytotoxicity. These findings suggest that FasL-mediated cytotoxicity may be acquired at more mature stages of NK-cell maturation than granule-mediated cytotoxicity.

CD2 Antigens↗

PubMed1997

Decreased pulmonary perfusion in hypersensitivity pneumonitis caused by Shiitake mushroom spores.

Hypersensitivity pneumonitis is an occupational hazard of mushroom workers. We describe a patient with severe hypersensitivity pneumonitis caused by spores of the Shiitake mushroom (Lentinus edodes) who showed a marked decrease in pulmonary perfusion, as demonstrated by pulmonary scintigraphy. This patient was treated successfully with prednisolone. These results suggest that pulmonary vasculitis may be associated with patients with hypersensitivity pneumonitis, and that steroid therapy may be clinically useful in treatment.

Alveolitis, Extrinsic Allergic↗

PubMed1997

Efficient harvest of in vivo IL-2-activated CD3+ lymphocytes for adoptive immunotherapy by selective leukapheresis (lymphocytapheresis).

Autologous activated lymphocytes are an alternative to tumor-infiltrating lymphocytes for adoptive immunotherapy. We developed a method of selective lymphocytapheresis that harvests large numbers of interleukin-2 (IL-2)-activated autologous T lymphocytes. Five patients with metastatic malignant melanoma received 2.4 x 10(6) IU/m2 IL-2 sc. once a day 5 days a week for 3 weeks before lymphocytapheresis. Four patients went through lymphocytapheresis without IL-2 pretreatment. After IL-2 pretreatment, activated memory T cells increased significantly. Increasing CD3+ cells paralleled the significant enhancement of the cytotoxic activity against an HLA-A2-matched allogeneic melanoma cell line during the 3 weeks of IL-2 pretreatment. Lymphocytapheresis was performed 72 h after the last IL-2 injection to obtain the maximum recovery of activated lymphocytes at the peak of the rebound phenomenon. IL-2 pretreatment resulted in many more lymphocytes in the harvest than without pretreatment. The percentage, number, and lytic units of CD3+ cells harvested by the differential apheresis were significantly higher than were present in peripheral blood before lymphocytapheresis. These results show that pretreatment of melanoma patients with low-dose IL-2 before lymphocytapheresis allows the selective harvest of large numbers of activated T lymphocytes for adoptive immunotherapy.

Adult↗

PubMed1997

Interleukin-6 is a useful marker for early prediction of the severity of acute pancreatitis.

Twelve patients with acute pancreatitis admitted to our department between January 1993 and December 1994 were studied prospectively and classified into two groups (severe group, five patients; mild group, seven patients), according to the criteria for grading severity of acute pancreatitis proposed by the Research Committee for Intractable Diseases of the Pancreas, Japanese Ministry of Health and Welfare (1990). To evaluate markers for early estimation of the severity of acute pancreatitis, we measured serum changes in various parameters. In the severe group interleukin-6 (IL-6) levels were increased significantly 5, 24, 72, and 120 h after the onset (p < 0.01), compared with the mild group. C-reactive protein (CRP), thrombin antithrombin III, and alpha 2-plasmin inhibitor plasmin complex levels were significantly increased only at the 72-h time point. Peak values of interleukin-8 (IL-8) and soluble human E selectin were observed at 5 and 72 h, respectively, after the onset. There was a significant correlation between IL-6 at 5 h and both pancreatic secretory trypsin inhibitor (r = 0.85) and CRP (r = 0.94) at 72 h. We therefore conclude that IL-6 is a useful marker for assessment of the severity of acute pancreatitis in its early stages.

Acute Disease↗

PubMed1997

Protective activity of Borrelia duttonii-specific immunoglobulin subclasses in mice.

To analyse the immune response of mice to Borrelia duttonii infection, BALB/c mice were inoculated intraperitoneally with B. duttonii strain 406K, and the titres of B. duttonii-specific immunoglobulins - IgM, IgG1, IgG2a, IgG2b and IgG3 - were determined by ELISA. IgM antibodies appeared first, followed by IgG2a and IgG3, and then IgG1 and IgG2b. The protective activity of individual classes and subclasses of B. duttonii-specific immunoglobulins was then determined by passive immunisation of BALB/c mice with immunoglobulin preparations purified by affinity chromatography. The mice were then challenged by intraperitoneal inoculation of B. duttonii. The study demonstrated that B. duttonii-specific IgM and IgG3 protected against the development of spirochaetaemia and death after borrelial infection, whereas B. duttonii-specific IgG1, IgG2a and IgG2b had low protective activities.

Animals↗

PubMed1997

Mapping of pump efficiency on the pressure-flow curve of a centrifugal blood pump.

Because pump efficiency is closely related to heat generation and blood trauma in a centrifugal blood pump, it is quite important to study pump efficiencies in a variety of conditions. In the present study, pump efficiencies were mapped on the pressure head-flow rate curves of 4 different pumps; BioMedicus BioPump (BP-80), Nikkiso (NK), Gyro C1E3, and Gyro PI601 (diameter of the impeller, NK: 50 mm, C1Ee3: 65 mm, and PI601: 50 mm). The mapping of pump efficiency revealed the following findings. First, the cone type (BP-80) has less pump efficiency than the impeller type (NK and C1E3); second, the miniaturization of the C1E3 to the PI601 has resulted in an increase in pump efficiency; and third, the diameter of the impeller may contribute to the pump efficiency of an im peller type pump. The mapping of the pump efficiency, as demonstrated in this study, is useful for the analysis of hydraulic pump performance in a wide range of clinically applied conditions.

Blood Flow Velocity↗

PubMed1997

Material of the double pivot bearing system in the Gyro C1E3 centrifugal pump.

A double pivot bearing system is adopted for the Gyro C1E3 centrifugal blood pump to achieve a completely sealless structure that prevents blood leakage and thrombus formation around the shaft. The double pivot bearing system is also a critical factor for blood trauma and durability of the C1E3 pump. This study focuses on the double pivot bearing material. The pump with the male ceramic and female polyethylene pivots (PE) was compared with the pump with the male ceramic and female ceramic pivots (CRM), pertaining to stability of the impeller spinning motion, hemolysis, and durability. At first, the wear rate of the pivots was recorded after operating the pumps in various rotational speeds. As for hemolysis, in vitro tests were carried out using fresh bovine blood in 2 conditions (5 L/min, 350 mm Hg and 5 L/min, 100 mm Hg). Then, stability of the spinning motion was investigated by evaluating the vibration of the pump. The two pumps with different female pivots were operated identically at 2,700 rpm, and the vibration signals were measured using an accelerometer that was mounted on the top of the pump housing. The following findings were obtained in this study. The wear sites were different between the PE and CRM. Most of the wear occurred at the top female polyethylene pivot in the PE. In contrast, most of the wear occurred at the top male ceramic pivot in the CRM. In addition, the amount of the initial wear was less and the wear rate was lower in the PE than in the CRM. The hemolysis caused by the PE was less than the hemolysis caused by the CRM. The vibration signals of the PE had less amplitude and a narrower range of frequency than the vibration signals of the CRM. In conclusion, the combination of materials male ceramic-female polyethylene are superior to the male ceramic-female ceramic for the double pivot bearing system of the Gyro C1E3 centrifugal pump because of less vibration, less hemolysis, and less wear.

Animals↗

PubMed1997

Eccentric inlet port of the pivot bearing supported Gyro centrifugal pump.

An eccentric inlet port is a unique feature of the pivot bearing supported Gyro Compact-1 Eccentric Inlet Port Model 3 (C1E3) centrifugal pump, a completely sealless centrifugal pump. The latest C1E3 has an eccentric inlet port with a 30 degree vertical angle. To investigate the adequacy of this 30 degree angle, flow visualization studies and in vitro hemolysis tests were performed, comparing 4 pumps, each with a different angle of the eccentric inlet port (0, 30, 60, and 90 degrees). The flow visualization study utilizing a tracer method focused on the flow pattern just distal to the inlet port of each pump, and each pump was operated at 5 L/min against 100 mm Hg and 5 L/min against 350 mm Hg. In the pumps with angles of 90 and 60 degrees, the flow direction changed horizontally, causing a vortex formation. In the pump with the 30 degree angle, the inflow did not change its course, resulting in minimal space for vortex formation. In the pump with the 0 degree angle, the inflow collided with the pump housing, resulting in a small vortex formation along the housing surface. The in vitro hemolysis tests at 5 L/min against 350 mm Hg revealed that the pump with the 30 degree angle was the least hemolytic and the pump with the 90 degree angle was the most hemolytic among the 4 pumps. These results suggest that the angle of the eccentric inlet port of the Gyro C1E3 pump should be 30 degrees to have less vortex formation and less red blood cell trauma.

Animals↗

PubMed1997

Vibration assessment for thrombus formation in the centrifugal pump.

To clarify the correlation of vibration and thrombus formation inside a rotary blood pump, 40 preliminary vibration studies were performed on pivot bearing centrifugal pumps. No such studies were found in the literature. The primary data acquisition equipment included an accelerometer (Isotron PE accelerometer, ENDEVCO, San Juan Capistrano, CA, U.S.A.), digitizing oscilloscope (TDS 420, Tektronix Inc., Pittsfield, MA, U.S.A.), and pivot bearing centrifugal pumps. The pump impeller was coupled magnetically to the driver magnet. The accelerometer was mounted on the top of the pump casing to sense radial and axial accelerations. To simulate the 3 common areas of thrombus formation, a piece of silicone rubber was attached to each of the following 3 locations as described: a circular shape on the center bottom of the impeller (CI), an eccentric shape on the bottom of the impeller (EI), and a circular shape on the center bottom casing (CC). A fast Fourier transform (FFT) method at 5 L/min against 100 mm Hg, with a pump rotating speed of 1,600 rpm was used. The frequency response of the vibration sensors used spans of 40 Hz to 2 kHz. The frequency domain was already integrated into the oscilloscope, allowing for comparison of the vibration results. The area of frequency domain at a radial direction was 206 +/- 12.7 mVHz in CI, 239.5 +/- 12.1 mVHz in EI, 365 +/- 12.9 mVHz in CC, and 163 +/- 7.9 mVHz in the control (control vs. CI p = 0.07, control vs. EI p < 0.001, control vs. CC p < 0.001, EI vs. CC p < 0.001, CI vs. CC p < 0.001). Three types of imitation thrombus formations were roughly distinguishable. These results suggested the possibility of detecting thrombus formation using vibration signals, and these studies revealed the usefulness of vibration monitoring to detect thrombus formation in a centrifugal pump.

Analysis of Variance↗

PubMed1997

Effects of pulsatile flow on gas transfer of membrane oxygenator: MENOX EL-4000 and Gyro C1-E3 pulsatile mode.

It is acknowledged that pulsatile flow enhances the gas exchange performance of membrane oxygenators. However, the data for currently developed oxygenators are limited. In this study, the effect of pulsatile flow was assessed utilizing the MENOX EL-4000 oxygenator. The in vitro test was performed following the Association for the Advancement of Medical Instrumentation (AAMI) standards. Pulsatile flow was produced by the Gyro C1-E3 centrifugal pump with periodical changing of the impeller speed. In Study 1, the following 3 groups were created and examined: nonpulsatile flow, pulsatile flow of 40 bpm, and pulsatile flow of 60 bpm. The blood flow rate was maintained at 3 L/min, and the V/Q ratio was 1. In Study 2, four groups were examined, nonpulsatile flow with V/Q = 1, nonpulsatile with V/Q = 2, pulsatile with V/Q = 1, and pulsatile with V/Q = 2. The blood flow rate was maintained at 4 L/min, and the pulse frequency was set at 40 bpm. In study 1, although O2 transfer was not enhanced, CO2 transfer was significantly improved (40-50%) by pulsatile flow, regardless of pulse frequency. Study 2 demonstrated that pulsatile flow resulted in improved CO2 transfer as did higher ventilation (V/Q = 2). Furthermore, even after applying higher ventilation, the pulsatile mode enhanced CO2 transfer more than the nonpulsatile mode. It was considered that the pulsatile mode induced an active secondary flow and enhanced mixing effects, and consequently CO2 transfer was improved. In conclusion, the pulsatile flow significantly enhanced the CO2 transfer of the MENOX oxygenator. It is indicated that applying the pulsatile mode is a unique and effective method to improve the gas exchange performance for a current membrane oxygenator.

Analysis of Variance↗

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

The simple in vitro thrombogenic test: modified methods for same priming pumps.

The improvement of antithrombogenicity is one of the major objectives for the development of blood pumps. Previously we reported that an in vitro thrombogenic test was useful as a pilot study, especially to predict thrombogenic areas. In this study we modified the method for testing pumps with identical priming volumes by eliminating the blood reservoir. Identical compact mock loops (priming volume of 53 ml, without pump) were constructed and tested with the same priming volume of Nikkiso centrifugal pumps, noncoated verus heparin-coated. Two pumps were run simultaneously using the same source of fresh heparinized human blood (activated clotting time [ACT] 150-250 s) for 4 or 6 h. Results indicated that the heparin-coated pump had a longer thrombus free period than the noncoated one. The thrombi location and forms were consistently in the same places the in vivo study had identified. It is suggested that this modified in vitro thrombogenic test is a feasible pilot study, as well as the one previously reported. The minimal priming volume will allow evaluation of multiple pumps simultaneously with the same source blood.

Anticoagulants↗

PubMed1997

Hydraulic assessment of the floating impeller phenomena in a centrifugal pump.

A compact eccentric inlet port centrifugal blood pump (C1E3) has been perfected for a long-term centrifugal ventricular assist device as well as a cardiopulmonary bypass pump. The C1E3 pump incorporates a sealless design and a blood stagnation free structure. The pump's impeller is magnetically coupled to the driver magnet in a sealless manner. The latest hemolysis study reveals that hemolysis is affected by the magnetic coupling distance between the driver and impeller magnet. Furthermore, a floating phenomenon can be observed in a pivot bearing supported pump. Attention was focused on the relationship between the floating phenomenon's characteristics and the magnetic coupling design in the C1E3 pump. Studies were conducted to evaluate the hydromechanical performance in the floating phenomenon. In this study, the relationship between the magnetic coupling design and the floating phenomenon was verified with a smooth spinning condition. The optimized magnetic coupling distance for the floating mode was estimated to be 12 mm for left ventricular assist device and 9 mm for cardiopulmonary bypass pump. Obtaining an optimal spinning condition is required for regulating the magnetic coupling force. To develop a double pivot bearing pump, it is necessary to establish an optimal spinning and/or floating condition and to determine the proper magnetic coupling and magnetic force between the impeller and driver.

Assisted Circulation↗

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

The hemolysis test of the Gyro C1E3 pump in pulsatile mode.

While a centrifugal pump is generally used for nonpulsatile blood flow, it can also produce a pulsatile flow by alternating the impeller rotational speed (rpm) periodically. However, there is a concern that this centrifugal pump pulsatile mode may induce added hemolysis as a result of the repeated acceleration and deceleration of rpm. Thus, a hemolysis study of the pulsatile modes of the Gyro C1E3 centrifugal pump (Gyro-P) was conducted. The results were then compared with the nonpulsatile mode of the same pump (Gyro-N) and the nonpulsatile BioMedicus BP-80 (Bio-N) pump. Three different conditions were simulated: left ventricular assist device (LVAD), cardiopulmonary bypass (CPB), and percutaneous cardiopulmonary support (PCPS). The beating rate of the Gyro-P was set at 40 bpm, with repetition of two different impeller speed (the lower being 70% of the higher speed). The 2 impeller speeds were set to obtain the same average flow as that of the nonpulsatile mode. The hemolysis results of the Gyro-P were comparable to or better than those of Bio-N, and no excessive hemolysis was observed, compared to the Gyro-N. In conclusion, The Gyro-P had an excellent hemolytic characteristic and generated no excessive hemolysis in most clinical usage conditions. With the concern of hemolysis eliminated, this pulsatile mode may have various possible mode advantages.

Analysis of Variance↗

PubMed1997

Hemolytic effect of surface roughness of an impeller in a centrifugal blood pump.

The present study investigates how the surface roughness of an impeller affects hemolysis in the pivot bearing supported Gyro C1E3 pump. This study focuses on particular areas of the impeller surface in the impeller type centrifugal pump. Seven Gyro C1E3 pumps were prepared with smooth surface housings and different impeller parts with different surface roughnesses. The vanes, top side, and backside of the impeller were independently subjected to vapor polishing, fine sand blasting, or coarse sand blasting to produce three different grades of surface roughness. These surfaces were then examined by a surface profile instrument. Using these pumps with different impellers, in vitro hemolysis tests were performed simulating cardiopulmonary bypass (5 L/min, 350 mm Hg). The findings of this study conclusively proved that surface roughness of the back side of the impeller has the greatest effect on hemolysis, followed by the top side and then the vanes. The following are reasons for these findings. First, the shear rate may be greater on the back side than on the top side because of the smaller gap between the back and the housing and the greater relative speed against the impeller. Second, the fluid beneath the impeller may have a longer exposure time because there is little chance for the fluid to mix beneath the impeller. Third, the shear rate may be greater on the top side of the impeller than on the vanes because a vortex formation occurs behind the vanes.

Analysis of Variance↗