Biomedical subjects

K Nakata

Publications and source records attributed to K Nakata.

At least 91 records · Page 5Linked to original sources

PubMed2000

Aberrant expression of immunoglobulin heavy chain genes in Epstein-Barr virus-negative, human immunodeficiency virus-related lymphoid interstitial pneumonia.

The two-step polymerase chain reaction (PCR) and sequencing analysis was used to analyze the immunoglobulin heavy chain variable (Ig V(H)) genes of open-chest biopsy or autopsy samples from five patients with Epstein-Barr virus-negative human immunodeficiency virus (HIV)-related lymphoid interstitial pneumonia (LIP), and the results were compared with those for Ig V(H) genes from five HIV-negative LIP patients. The findings of this study are consistent with the different immunological situations of HIV-related and HIV-negative LIP. (a) The Ig V(H)3 subgroup was underexpressed in three of five cases of HIV-related LIP. In contrast, none of the HIV-negative cases showed this abnormality. Because the Ig V(H)3 subgroup encodes the largest portion of Ig V(H) genes, a depletion of B cells expressing Ig V(H)3 genes reflects a major alteration in the B-cell compartment. (b) All HIV-related LIP cases demonstrated two or three oligoclonal populations. HIV-negative cases showed minor monoclonal or polyclonal populations, but not oligoclonal ones. These oligoclonal populations suggest the coexistence of several occult clonal B-cell populations in HIV-related LIP. (c) Some oligoclonal clones in HIV-related LIP showed mutated framework regions not demonstrated in HIV-negative clones. This degree of variation exceeds the usual mutation rate for frameworks, suggesting a role for framework residues in antigen binding. (d) The frequency of D-D fusions of minor oligoclonal clones (HIV-related LIP) is higher than that of minor monoclonal clones (HIV-negative LIP). Such D-D fusions may enhance the probability of expression of antibodies capable of binding HIV glycoproteins.

Adult↗

PubMed2000

A clinical use of the Kyocera Gyro C1E3 centrifugal pump.

The Kyocera Gyro C1E3 centrifugal blood pump was clinically applied for a cardiopulmonary bypass (CPB) of coronary artery bypass grafting (CABG). The patient was 72-year-old male with postinfarction unstable angina. The surgery was carried out on November 20, 1998. The air inside the pump was easily and quickly removed, and its controllability was excellent. The pump flow during operation was maintained 2.2 L/m2. Total CPB time was 173 min. Perioperative parameters of hemolysis and cytotoxicity were not remarkably changed. Macroscopically and microscopically, there were no thrombi inside the pump after usage. This is the first reported case of clinical use of the Kyocera Gyro C1E3 pump.

Aged↗

PubMed2000

Analysis of the arterial blood pressure waveform using Fast Fourier Transform technique during left ventricular nonpulsatile assistance: in vitro study.

The arterial blood pressure waveform is variable during left ventricular assistance. The aim of this study is to examine the correlation between the left ventricular assist device (LVAD) condition and the arterial blood pressure waveform in a fixed cardiac output condition using a mock circuit. This mock circulation loop was composed of an aortic compliance chamber, a left atrial compliance chamber, a pneumatic pulsatile pump as a native heart, and a rotary blood pump representing the LVAD with left atrial drainage. The Fast Fourier Transform technique was utilized to analyze the arterial blood pressure waveform and calculate the pulsatility index (PI) and the pulse power index (PPI). The PI and PPI decreased with the increase of the LVAD rotational speed, exponentially. There was a significant negative correlation between the PI, PPI, and the LVAD rotational speed, flow rate, and assist ratio. The best correlation was observed between the PPI and the assist ratio (r = 0.986). From this viewpoint, an ideal LVAD condition may be estimated from the pulsatility change of the arterial blood pressure waveform.

Blood Pressure↗

PubMed2000

Estimation of pump flow rate and abnormal condition of implantable rotary blood pumps during long-term in vivo study.

The control system for an implantable rotary blood pump is not clearly defined. A detection system is considered to be necessary for pump flow monitoring and abnormal conditions such as back flow or a sucking phenomenon where the septum or left ventricle wall is sucked into the cannula, etc. The ultrasound flowmeter is durable and reliable but the control system should not be totally dependent on the flowmeter. If the flowmeter breaks, the rotary blood pumps have no control mechanism. Therefore, the authors suggest controlling the pumps by an intrinsic parameter. One left ventricular assist device (LVAD) calf model was studied where the flow rate and waveform of the pump flow proved to identify the sucking phenomenon. Thus, the pump flow rate was calculated from the required power, motor speed, and heart rate. The value of the coefficient of determination (R2) between the measured and estimated pump flow rate was 0.796. To estimate this abnormal phenomenon, 2 methods were evaluated. One method was the total pressure head in which the pump flow rate and motor speed were estimated. During normal conditions the total pressure head is 79.5 +/- 7.0 mm Hg whereas in the abnormal condition, it is 180.0 +/- 2.8 mm Hg. There was a statistical difference (p < 0.01). Another method is using a current waveform. There is an association between the current and pump flow waves. The current was differentiated and squared to calculate the power of the differentiated current. The normal range of this value was 0.025 +/- 0.029; the abnormal condition was 11.25 +/- 15.13. There was a statistical difference (p < 0.01). The predicted flow estimation method and a sucking detection method were available from intrinsic parameters of the pump and need no sensors. These 2 methods are simple, yet effective and reliable control methods for a rotary blood pump.

Animals↗

PubMed2000

Jostra Rota Flow RF-30 pump system: a new centrifugal blood pump for cardiopulmonary bypass.

The Rota Flow pump is a fully integrated centrifugal pump system in the Jostra heart-lung machine HL-20 with features such as a less friction mono-pivot bearing system, sealless pump housing, and spiral housing. To evaluate its biocompatibility, antithrombogenesity, and hemolysis, we used it as a main pump of cardiopulmonary bypass (CPB) in coronary artery bypass grafting (CABG) cases and compared it with the BioMedicus pump. From February 1999 to May 1999, 30 consecutive patients underwent CABG under conventional CPB. Fifteen cases were supported by the Rota Flow RF-32 (Group R), and the remaining 15 were pumped by the BioMedicus BP-80 (Group B). In both groups, the flow rate was controlled in an equivalent value. Blood sampling was as follows: preoperative, 60 min after, postoperative Days (POD) 0, 1, and 2. We evaluated the plasma free hemoglobin (fHb) as the hemolysis parameter, beta-thromboglobulin (beta-TG) and platelet factor IV (PF-4) as the platelet deterioration index, C3, C4, and CH50 as complement activation, coagulation function, fibrinolytic factor and thrombomodulin, nitric oxide (NO), and endothelin as endothelial deterioration. This system was very easily and simply controlled and had excellent response. Perioperative laboratory data were not markedly changed in either group. The Rota Flow demonstrated equivalent value of biocompatibility and hemolysis as compared with the BioMedicus BP-80, which is a standard centrifugal pump. After pumping, no thrombus formation or pivot wear was observed inside the pump. This atraumatic, small centrifugal pump is suitable not only for CPB but also for long-term circulatory support.

Analysis of Variance↗

PubMed2000

Development of the NEDO implantable ventricular assist device with Gyro centrifugal pump.

The Gyro centrifugal pump, PI (permanently implantable) series, is being developed as a totally implantable artificial heart. Our final goal is to establish a "functional TAH," a totally implantable biventricular assist system (BiVAS) with centrifugal pumps. A plastic prototype pump, Gyro PI 601, was evaluated through in vitro and in vivo studies as a single ventricular assist device (VAD). Based upon these results, the pump head material was converted to a titanium alloy, and the actuator was modified. These titanium Gyro pumps, PI 700 series, also were subjected to in vitro and in vivo studies. The Gyro PI 601 and PI 700 series have the same inner dimensions and characteristics, such as the eccentric inlet port, double pivot bearing system, secondary vane, and magnet coupling system; however, the material of the PI 700 is different from the PI 601. The Gyro PI series is driven by the Vienna DC brushless motor actuator. The inlet cannula of the right ventricular assist system (RVAS) specially made for this system consists of 2 parts: a hat-shaped silicone tip biolized with gelatin and an angled wire reinforced tube made of polyvinylchloride. The pump-actuator package was implanted into 8 calves in the preperitoneal space, bypassing from the left ventricle apex to the descending aorta for the left ventricular assist system (LVAS) and bypassing the right ventricle to the main pulmonary artery for the RVAS. According to the PI 601 feasibility protocol, 2 LVAS cases were terminated after 2 weeks, and 1 LVAS case and 1 RVAS were terminated after 1 month. The PI 700 series was implanted into 4 cases: 3 LVAS cases survived for a long term, 2 of them over 200 days (72-283 days), and 1 RVAS case survived for 1 month and was terminated according to the protocol for a short-term antithrombogenic screening and system feasibility study. Regarding power consumption, the plastic pump cases demonstrated from 6.2 to 12.1 W as LVAS and 7.3 W as RVAS, the titanium pump cases showed from 10.4 to 14.2 W as LVAS and 15.8 W as RVAS. All cases exhibited low hemolysis. The renal function and the liver function were maintained normally in all cases throughout these experimental periods. In the 2 RVAS cases, pulmonary function was normally maintained. No calves demonstrated thromboembolic signs or symptoms throughout the experiments except Case 1 with the plastic pump. However, in the plastic pump cases, bilateral renal infarction was suspected in 2 cases during necropsy whereas no abnormal findings were revealed in the titanium pump cases. There were also no blood clots inside the PI 700 series. As for the 601, the explanted pumps demonstrated slight thrombus formations at the top and bottom pivots except in 1 case. The Gyro PI series, especially the PI 700 series, demonstrated superior performance, biocompatibility, antithrombogenicity and low hemolysis. Also, the durability of the actuator was demonstrated. Based on these results, this titanium centrifugal pump is suitable as an implantable LVAS and RVAS. It is likely that the Gyro PI series is a feasible component of the BiVAS functional TAH.

Animals↗

PubMed2000

Gyro pump wear and deformation analysis in vivo study: creep deformation.

The Gyro pump has a double pivot bearing system to support its impeller. In this study, the integrity of the bearing system was examined after ex vivo studies. The pumps were implanted into calves and evaluated for different periods as a paracorporeal left ventricular assist device (LVAD). One pump was subjected to a test of 30 days, 1 for 15 days, 4 for 14 days, 1 for 10 days, 1 for 7 days, 2 for 4 days, and 4 for 2 days. One additional pump was subjected to percutaneous cardiopulmonary support (PCPS) condition for 6 days (total pressure head 500 mm Hg with a pump flow rate of 3 L/min). The anticoagulation treatment consisted of a continuous administration of heparin to maintain an achieved clotting time (ACT) of 200-250 s during the LVAD study and 250-300 s during the PCPS study. After the experiment, the pumps were disassembled, and the wear and deformation of male and female bearings were analyzed. There were no dimensional changes on male bearings but there were on female bearings. Wear and deformation of the female bearings were calculated as follows: wear and deformation = (depth of female before pumping) - (depth after pumping). Thirteen assembled Gyro pumps were disassembled to measure the depth of the female bearings before pumping. There was no statistical relationship between the wear and deformation and the motor speed x driving period. From these results, the deformation was not due to wear but to the creep or elastic deformation. This study suggested that the double pivot bearing system of the Gyro pump is highly durable.

Animals↗

PubMed2000

Antithrombogenicity evaluation of a centrifugal blood pump.

The Gyro C1E3 pump was developed not only for cardiopulmonary bypass but also as a short-term assist device. The main purpose of this study was to examine the correlation between the thrombus formation factor and the Gyro C1E3 pumps. Seven pumps were implanted into 3 calves and evaluated for different periods of duration as a paracorporeal left ventricular assist device (LVAD). One pump was subjected to percutaneous cardiopulmonary support condition (PCPS) (total pressure head 500 mm Hg with a pump flow rate of 3 L/min). The anticoagulation treatment consisted of a continuous administration of heparin to maintain an activated clotting time (ACT) of 200-250 during the LVAD study and 250-300 during the PCPS study. After the experiment, the pumps were disassembled and examined. In cases where there were any blood-derived deposits inside the pumps, the dry weight of these thrombi that adhered to the bearing area of the pump was measured. A multiple correlation was attempted to speculate possible thrombus formation. The estimated dry weight of thrombi was calculated from pump flow rate, pumping day, motor speed, and activated clotting time. This equation was estimated dry weight of thrombi = 1.140 x pump flow rate -0.001 motor speed + 1.652 pumping time -0.041 x ACT + 2.198 R2 = 0.944. This study suggested that there was a possibility to calculate the amount of adhered thrombus formation from pump flow rate, motor speed, pumping day, and ACT.

Animals↗

PubMed2000

Particles released from the Gyro C1E3 during simulated extracorporeal circulation.

Evaluation of released particles from the blood pump during extracorporeal circulation is an important aspect because the particles may cause microembolism. The Gyro C1E3 is a centrifugal blood pump that has an impeller suspended by double pivot bearings inside the housing; therefore, it is important to evaluate the released particles. The C1E3 was driven for 14 days to simulate clinical left ventricular assist device (LVAD) and percutaneous cardiopulmonary support (PCPS). Also, a roller pump was driven for 2 days as a comparison. Released particles were weighed and examined by SEM. After 14 days of pumping, the particles from the C1E3 were 238.6 microg in an LVAD condition. The particles with the roller pump were 270.2 microg after only 2 days. Average particle sizes with the roller pump and C1E3 were 3.7 and 0.6 microm, respectively. These results suggest that the Gyro C1E3 substantially reduces the risk of microembolism from released particles.

Biocompatible Materials↗

PubMed2000

Impeller design for a miniaturized centrifugal blood pump.

The impeller design for a miniature centrifugal blood pump is an important consideration since the small diameter impeller requires higher rotational speed, which may cause more blood trauma compared to the larger diameter impeller. Three different impeller vanes (straight vanes with a height of 4 mm and 8 mm, and 8 mm curved vanes) of which the diameter was 35 mm were subjected to hydraulic performance and hemolysis tests in the same pump housing. Both straight vane impellers attained left ventricular assist condition (5 L/min against 100 mm Hg) at 2,900 rpm while the curved vane required 3,280 rpm. There was no significant hemolysis difference between the tall and short vanes. The curved impeller vanes did not exhibit sufficient hydraulic performance when compared to the straight vanes. The straight vane impellers, even with different heights, were incorporated into the same pump housings, and the vane heights did not drastically change the hydraulic performance or hemolysis.

Equipment Design↗

PubMed2000

Analysis of the arterial blood pressure waveform during left ventricular nonpulsatile assistance in animal models.

When the rotary blood pump is used as a left ventricular assist device (LVAD), the arterial blood pressure waveform changes with the LVAD condition. Based on evidence from an in vitro study, the change of the arterial blood pressure waveform during left ventricular assistance was evaluated using animal models. After the left pleural cavity was opened through the fifth intercostal space under general anesthesia, a rotary blood pump was implanted as an LVAD into 6 healthy calves. The direct left carotid arterial blood pressure waveform was measured and recorded by an oscilloscope. The Fast Fourier Transform technique was utilized to analyze the arterial blood pressure waveform and calculate the pulsatility index (PI) and the pulse power index (PPI). Similar to the in vitro study, the PI and PPI decreased exponentially with the increase of the LVAD assist ratio. By using this analysis methodology, a physiologically effective ventricular assistance might be achieved.

Animals↗

PubMed2000

The gravity sag view: a simple radiographic technique to show posterior laxity of the knee.

We introduce a simple radiographic technique of taking a "gravity sag view" to show sagittal laxity secondary to posterior cruciate ligament injury. Side-to-side differences of the tibia-femur step-off measured with these radiographs have proved to be useful parameters for evaluating posterior laxity. This radiographic technique is recommended instead of routine lateral radiographs taken with the knee kept recumbent.

Humans↗

PubMed2000

P2Y(2) receptor stimulation increases tear fluid secretion in rabbits.

PURPOSE: The purinergic P2Y(2) receptor agonists stimulate active Cl-transport across the excised rabbit conjunctival tissue in vitro. We determined whether UTP or ATP could increase the tear volume and change tear fluid composition in normal rabbits in vivo. METHODS: Fifty mL was applied to rabbit eyes of UTP, ATP at concentrations of 0.1, 0.3, 1, 3, 8.5% (1.8-154 mM) or saline. A modified Schirmer test with topical anesthesia was performed 5, 15, 30 and 60 min after the instillation. In studies lasting 30 days, 50 microL of 0.5% UTP was applied 6 times a day for 4 weeks. Tear samples were collected from the conjunctival sac with a glass microcapillary. The protein profile of the tear fluid was analyzed by SDS-polyacrylamide gel electrophoresis and total protein was measured with the Bradford assay. The Easy-Titer rabbit IgG assay kit was used for the determination of immunoglobulin G (IgG). RESULTS: UTP had dose-dependent stimulatory effects on tear secretion. It maximally increased tear secretion about 4-fold 15 min after its application. Similar effects were obtained with ATP. Repeated treatment with UTP reproducibly increased tear volume. Furthermore, UTP did not decrease total protein and IgG concentration in tear fluid and it had no effect on the protein profile. CONCLUSION: These data indicate that activation of P2Y(2) receptor increases tear fluid secretion accompanied with some proteins in normal rabbits. The purinergic agonists, UTP and ATP, have potential therapeutic value in the treatment of dry eye.

Adenosine Triphosphate↗

PubMed2000

Fine localization of a major disease-susceptibility locus for diffuse panbronchiolitis.

Diffuse panbronchiolitis affecting East Asians is strongly associated with the class I human leukocyte antigen (HLA) alleles. Recent observations suggest that a major disease-susceptibility gene may be located between the HLA-B and HLA-A loci in the class I region of the major histocompatibility complex on chromosome 6. To test this possibility, we analyzed 14 polymorphic markers in 92 Japanese patients and 93 healthy controls. Of these, seven marker alleles, including HLA-B54 and HLA-A11, were significantly associated with the disease. Maximum-likelihood haplotype analysis and subsequent direct determination of individual haplotypes identified a group of disease-associated haplotypes, one of which contained all seven disease-associated marker alleles. Another haplotype, containing HLA-B*5504, was also associated with the disease. All these haplotypes seem to have diverged from a common ancestral haplotype in East Asians and share a specific segment containing three consecutive markers between the S and TFIIH loci in the class I region. Furthermore, one of the markers within the candidate region showed the highest delta value, indicating the strongest association. Of 20 Korean patients with diffuse panbronchiolitis, 17 also shared the combination of the disease-associated marker alleles within the candidate region. These results indicate that an HLA-associated major susceptibility gene for diffuse panbronchiolitis is probably located within the 200 kb in the class I region 300 kb telomeric of the HLA-B locus on the chromosome 6p21.3.

Alleles↗

PubMed2000

Influenza A virus-binding activity of glycoglycerolipids of aquatic bacteria.

As the aqueous sphere has been proposed to be an important source medium for the virus infection of land animals, the glycolipids of some aquatic organisms were examined for human influenza A virus-binding activity. Active compounds were not found among the eight echinoderm gangliosides, but two active non-sialylated glycoglycerolipids were isolated from an aquatic bacterium, Corynebacterium aquaticum. The structural formula of one of them, H632A, was elucidated to be 1-14-methyl-hexadecanoyl-3-alpha-D-galactopyranosyl-(1-->3)-6-(12-met hyl-tetradecanoyl)-1-alpha-D-mannopyranosyl]-sn-glycerol. The latter together with reported one elsewhere, S365A, 1-14-methyl-hexadecanoyl-3-[alpha-D-mannopyranosyl-(1-->3)-6-(12-meth yl-tetradecanoyl)-1-alpha-D-mannopyranosyl]-sn-glycerol, apparently bound to three human influenza viruses, A/PR/8/34 (H1N1), A/Aichi/2/68 (H3N2), and A/Memphis/1/71 (H3N2), exhibiting 7-12% (H632A) and 10-22% (S365A) of the activities of the control substances (Neu5Acalpha2-3-paragloboside and Neu5Acalpha2-6- paragloboside). Additionally, these glycolipids were assumed to have virus-neutralizing activities for the following two reasons: (i) The hemagglutination and hemolysis activities of the viruses were inhibited by the glycolipid. (ii) The leakage of a cytosolic enzyme (lactate dehydrogenase) from Madin-Darby canine kidney cells on virus infection was prevented by the glycolipids to nearly the same extent as by fetuin. This is the first evidence of the binding- and neutralizing-abilities of native glycoglycerolipids as to influenza viruses.

Animals↗

PubMed2000

High resistance to oxygen radicals and heat is caused by a galactoglycerolipid in Microbacterium sp. M874.

Microbacterium sp. M874 produced a glyceroglycolipid, di-O-12-methyl-tetradecanoyl-3-O-beta-D-galactopyranosyl-sn-glycerol, at about the 50 microM level. Though the strain was highly resistant to tertiary-butyl hydroperoxide (tBHP) in a glycolipid-productive medium, the resistance was reduced in a nonproductive medium. Exogenous addition of the glycolipid to the nonproductive culture restored the resistance. This addition also increased the resistance to heat, ethanol, and 4-chloro-1-naphthol, in which oxygen radicals might participate. The parallel relationship found in strain M874 mutants between glycolipid productivity and resistance to tBHP or heat suggested that the resistance was mainly caused by the glycolipid. On addition of the glycolipid to a glycolipid-nonproductive culture, it was immediately incorporated into the cells and functioned as an anti-oxygen radical reagent. Thereafter, its intracellular level remained largely unchanged for at least 5 h, even in the presence of tBHP, and its activity was maintained. The glycolipid at 142 microM was sufficient to prevent the cytotoxicity induced by 88.9 mM tBHP. The glycolipid production was not induced by pretreatment with a low level of tBHP or a sublethal heat shock. In brief, the glycolipid might play an essential role in the prevention of damage by oxygen radicals in the glycolipid-producing bacterium.

Galactolipids↗

PubMed2000

Rescuing activity of galactoglycerolipids from cellular lesions induced by 5-aminolevulinic acid.

An anti-oxygen radical reagent of a bacterial metabolite, M874 monogalactoglycerolipid (di-O-12-methyl-tetradecanoyl-3-O-beta-D-galactopyranosyl-sn-glycerol ), was tested for its ability to protect two organisms against cellular lesions induced by 5-aminolevulinic acid (ALA) and light. In Corynebacterium flavescens ATCC 10340, extracellular uroporphyrin and coproporphyrin were the main porphyrin products. Although less than 2 mM ALA increased porphyrin synthesis, ALA levels above 3 mM inhibited the synthesis. Depending on the light intensity, the amount of porphyrin decreased and ALA-induced cytotoxicity increased. The lesion was more severe in the case of coproporphyrin than uroporphyrin. The porphyrin lesion produced in low intensity light (300 lx) was considerably reduced by 100 microM M874 glycolipid, although the reduction in intense light (3,000 lx) was restricted to a lower level. Similar results were obtained with radish (Raphanus sativus). The ALA concentration that inhibited porphyrin synthesis and stem growth was similar to that seen with C. flavescens. Although the exogenous addition of M874 glycolipid to the radish did not prevent ALA-induced cellular injury, the co-culture of radish and a glycolipid producing bacterium (Microbacterium sp. M874) resulted in a significant prevention of cellular injury. This was true only under enforced adhesion conditions through the action of a polysaccharide flocculant H12. Some species of monogalactoglycerolipids were found in Corynebacterium and radish that showed prominent oxygen radical-protecting activities similar to that of M874 glycolipid. These monogalactoglycerolipids might function in vivo as agents to prevent ALA-induced cytological lesions, although the concentrations were low in Corynebacterium and radish.

Aminolevulinic Acid↗

PubMed2000

Lactoferrin protects against UV-B irradiation-induced corneal epithelial damage in rats.

PURPOSE: Lactoferrin supplementation suppresses ultraviolet light B (UV-B)-induced oxidation of cultures of human corneal epithelial cells. To investigate the protective effect of lactoferrin containing eyedrops against UV-B-induced corneal damage in vivo, we examined lactoferrin efficacy in a rat UV-B keratitis model. METHODS: Sprague-Dawley rats were irradiated with >10 kJ/m2 after anesthetization, and then corneal epithelial defect was observed at 24 h postirradiation. The pre- or postapplication of vehicle or lactoferrin-containing eyedrops was performed, and then corneal epithelial damage was scored based on fluorescein staining. RESULTS: Posttreatment with lactoferrin did not inhibit the extent of corneal damage and did not affect wound healing. However, pretreatment by topical application of lactoferrin suppressed development of a corneal epithelial defect induced by UV-B irradiation in rats. CONCLUSION: These results suggest that the presence of lactoferrin in human tear fluid may inhibit UV-induced corneal epithelial damage.

Animals↗