Biomedical subjects

T Agishi

Publications and source records attributed to T Agishi.

197 records · Page 11Linked to original sources

PubMedDate not supplied

Clinical application of vascular closure staple clips for blood access surgery.

We investigated the usefulness of nonpenetrating titanium vascular closure staple (VCS) clips developed for anastomosis of peripheral blood vessels. VCS clip applier systems (Autosuture; United States Surgical Corporation, Norwalk, CT) were used for 10 patients on hemodialysis who needed peripheral vascular anastomoses for blood access. Two arteriovenous (AV) fistulas, one closure of a fistula with reconstruction of the radial artery, six vascular graft implantations, and one vascular graft closure were performed. Medium clips were used for AV fistulas and large clips for vascular graft implantation. It took 12 min, on average, for vascular access graft anastomoses and 8.5 min, on average, for the AV fistulas. In two patients, bleeding from the anastomosed site occurred after declamping and additional sutures were required; however, neither hematoma nor wound infection occurred at 9 to 12 months after surgery. In one patient, stenosis of the graft-venous junction was found and was successfully treated by percutaneous transluminal angioplasty. The VCS clip applier is easy to manipulate, is as safe as hand-suture methods, and has time saving potential. We conclude that these VCS clips are useful for vascular anastomoses of blood access.

Anastomosis, Surgical↗

PubMedDate not supplied

Solute removal characteristics of continuous recirculating peritoneal dialysis in experimental and clinical studies.

Continuous recirculating peritoneal dialysis (CRPD) was introduced to enhance solute removal efficiency in conventional peritoneal dialysis (PD) therapies such as continuous ambulatory peritoneal dialysis (CAPD). In CRPD, a portion of the dwell dialysate in the patient's peritoneal cavity is drained through a double-lumen catheter and purified by an extracorporeal dialyzer. In this study, solute removal characteristics and safety of CRPD are examined in ex vivo and clinical studies. Recirculation dialysis experiments using nine dogs (13.6 +/- 2.5 kg of body weight) were carried out for 240 min in the ex vivo study, whereas another seven dogs (12.1 +/- 2.8 kg) received conventional peritoneal dialysis (CPD) (120 min dwelling x 2) and six additional dogs (11.9 +/- 2.7 kg) received a Tidal PD (20 min dwelling x 12; 50% of tidal volume ratio) as controls. The ex vivo study revealed that CRPD has a higher efficiency for solute removal than CPD and is equivalent to Tidal PD. In the BUN reduction rate, the 19.4 +/- 5.5% in 240 min CRPD (n = 9) was significantly higher (p < 0.05) than the 3.5 +/- 3.6% in 240 min CPD (n = 7) and equivalent to the 17.3 +/- 4.7% in 240 min Tidal PD (n = 6). Continuous recirculating peritoneal dialysis maintained a low UN level in the peritoneal cavity due to dialysis with an extracorporeal dialyzer. This tendency was also seen in creatinine removal. In the clinical study, CRPD (n = 10) and CPD (n = 5) treatments were used in three renal failure patients. Higher solute removal efficiency was shown in CRPD than in CPD treatments, and the urea peritoneal clearance was 14.1 +/- 4.4 ml/min in CRPD (n = 10), significantly higher (p < 0.05) than the 7.3 +/- 2.1 ml/min in CPD (n = 5). No fibrin formation occurred during CRPD treatments.

Adult↗

PubMedDate not supplied

Can cytokines be removed by hemofiltration or hemoadsorption?

To study the removability of pro-inflammatory cytokines by hemofiltration (HF), we performed experimental HF with various high-flux membranes (HFM) using a closed circuit system filled with monocyte-free human plasma, which contained TNFalpha, IL-1beta, and IL-6. Plasma and filtrate samples were taken before and 1, 2, 3, and 4 hours after the initiation of HF, and each cytokine was determined by enzyme-linked immunosorbent assay. IL-1beta was well removed through filtration during experimental HF using HFM (PAN>CTA>PMMA>PS). TNFalpha and IL-6 were only minimally filtered out by HF using HFM. TNFalpha was removed to some extent by using PS, and IL-6 was partially removed by using PMMA during experimental HF through other mechanisms, such as adsorption, than the filtration. IL-1beta and IL-6 were effectively removed by HA using charcoal adsorbent column, especially during the first 2 hours, while TNFalpha was only partly removed.

Adsorption↗

PubMedDate not supplied

Effects of internal filtration on the solute removal efficiency of a dialyzer.

To improve solute removal efficiency, several types of dialyzers with enhanced internal filtration were introduced for clinical application. In these dialyzers, enhanced internal filtration increased convective transport of the solute, in addition to diffusive transport. In this study, the effects of internal filtration on solute removal efficiency were examined by both analytic and experimental studies. Internal filtration is affected by blood (Q(B)) and dialysate (Q(D)) flow rates; the patient's hematocrit and plasma level of total protein; and the effective length (L(eff)), inner diameter (D), and density ratio (DR) of the hollow fibers. An analytic model was introduced for the estimation of the changes in mass and momentum along the dialyzer. It clarified the effects of these parameters on maximum internal filtration flow rate (Q(IF)) and clearance (K) of urea (60 daltons), vitamin B(12) (1,355), and myoglobin (17,000). As a result of the analytic study, Q(IF) was increased, resulting in a smaller D, a longer L(eff), and a larger DR value. Several types of dialyzers with the same cellulose triacetate membrane, produced by Toyobo Co, Ltd., Ohtsu, Japan, and Nissho Corporation, Kusatsu, Japan, were used for the experimental study. An in vitro evaluation using myoglobin solution showed the same trends as found in the analytic study. For example, a dialyzer with 150 microm of D has a 72.0 ml/min myoglobin K value, much higher than that of 53.7 ml/min for a dialyzer with 200 microm of D under constant Q(B) (300 ml/min) and DR (50%) values. Development of a dialyzer with enhanced internal filtration, however, should take the patient's safety into account, and hemolysis and endotoxin invasion from the dialysate to the patient should be avoided.

Filtration↗

PubMedDate not supplied

Extracorporeal adsorption as a new approach to treatment of botulism.

Botulism is a paralytic disease caused by a toxin produced by the bacterium Clostridium botulinum. Outbreaks of the illness take place with a mortality rate of 10%, and the potential terrorist use of the toxin has become a serious concern. The current treatment includes administration of antitoxin, which can cause serious allergic reactions. Recently, we have successfully treated a 64 year old woman with the illness with IMMUSORBA TR350 (Asahi Medical, Tokyo, Japan), an extracorporeal adsorptive column containing polyvinylalcohol-tryptophan as an adsorptive agent, which has been widely used in Japan to treat myasthenia gravis and Guillain-Barre syndrome. Initially, the patient developed ocular muscle weakness and a variant of the Guillain-Barre syndrome was suspected. After extracorporeal treatment, her neurologic symptoms remarkably improved. After a series of treatments, botulinum toxin type B was isolated in the food she had eaten, establishing the diagnosis. An in vitro study revealed that the adsorptive column removed botulinum toxin to a significant extent. Our recent findings suggest that treatment with the adsorptive column TR350 can be a feasible option for botulism, which is a rare but potentially lethal disease.

Adsorption↗

PubMedDate not supplied

Bioartificial endocrine pancreas (Bio-AEP) for treatment of diabetes: effect of implantation of Bio-AEP on the pancreas.

Recently, we described a diffusion chamber for a bioartificial endocrine pancreas (Bio-AEP). Pancreatic islet cells in the Bio-AEP device were isolated from the immune system of the host by an artificial barrier, while nutrients, electrolytes, oxygen, and bioactive secretory products were exchanged across this barrier. This experiment was designed to evaluate whether the diffusion chamber could be useful as a Bio-AEP in the treatment of diabetes. Six streptozotocin (STZ)-induced diabetic rats each received a diffusion chamber containing 8 x 10(6) MIN6 cells as a xenograft Bio-AEP. In the STZ diabetic rats with Bio-AEPs, a return to normoglycemia was observed up to 30 weeks after implantation, without the use of any immunosuppressant. A gradual increase in the body weight of the rats was also observed. In three STZ diabetic rats, diffusion chambers without MIN6 cells were implanted as a sham operation. The fasting blood glucose levels in these three rats remained higher than 600 mg/dl, after implantation, and they lost weight. Thirty-five weeks after implantation, the pancreata were removed from the rats that underwent xenoimplantation, those that had the sham operation, and the normal control rats. In the sham-operated animals, the exocrine tissues of the pancreata were vacuolated and pancreatic B cells were not seen in the islets. In contrast, in the pancreata from the xenoimplantation, the exocrine tissues were normal, and a few pancreatic B cells were seen in the islets. These results indicated that xenoimplantation using the Bio-AEP might retard the progress of diabetes.

Animals↗

PubMedDate not supplied

Experimental studies on improved polyester-polyurethane vascular grafts for hemodialysis.

A new poly(ether-urethane) graft (PEUG) was developed. Although this graft had several advantages, it became clear that it also had disadvantages, such as the formation of pseudoaneurysms by repeated puncture. To overcome these problems, the PEUG was modified to add mechanical strength by incorporating knitted polyester fibers. Physical strength tests were done, and it was concluded that the graft was more durable than either PEUG or expanded polytetrafluorethylene. Additional experiments showed that gelatin coated PEUG implanted in dogs facilitated endothelialization of the internal surface and improved its patency, although these observations were too short to draw any definitive conclusions.

Animals↗

PubMedDate not supplied

Prolongation of cardiac xenograft function after reduction of natural antibodies using double filtration plasmapheresis.

A double filtration plasmapheresis (DFPP) technique was applied to selectively remove the natural antibodies in discordant xenotransplantation. A swine heart was heterotopically transplanted in a canine neck after two DFPP procedures during which 200 to 500 ml of plasma were replaced with the same amount of Hartman's solution containing 7% human albumin. Mean removal rate of IgC and IgM by DFPP ranged from 74.2 +/- 0.5 to 95.9 +/- 2.8%. The anti-swine lymphocytotoxic reaction of canine serum was decreased after DFPP but still remained in low titers. Mean graft survival time in the group treated by DFPP in which 1000 ml of plasma was totally replaced was prolonged to 107 +/- 47 min, while it was 9 +/- 5 min in the group without any treatment (p less than 0.01). Deposits of canine IgM and C3 on the vascular endothelium of the graft were observed on immunofluorescence, while there were no deposits of IgG. In conclusion, DFPP effectively removed the natural antibodies, resulting in prolongation of xenograft survival time. Immunofluorescence study suggested that natural IgM antibodies played an important role in this xeno-hyperacute rejection.

Animals↗

PubMedDate not supplied

Immunoadsorption of anti-A or anti-B antibody for successful kidney transplantation between ABO incompatible pairs and its limitation. Japanese Biosynsorb Research Group.

Kidney transplantation between ABO incompatible pairs, contraindicated because of a high incidence of hyperacute rejection episodes, has become feasible after provisional removal of anti-A or anti-B antibody from recipient canidates. Initially, a total of 54 patients were scheduled to be transplanted with ABO incompatible kidneys after removal of anti-A or anti-B antibody by immunoadsorption, using A or B antigen expressing trisaccharide immobilized on silica beads. Levels of anti-A and/or anti-B antibody (-ies) were negative (below less than X8 dilution) after three to four immunoadsorption treatments, and, thereafter, kidneys were successfully transplanted in 47 patients (incompatibility in A:21, B:25, AB:1). However, in four patients, anaphylactoid reaction occurred immediately after initiation of immunoadsorption, and double filtration plasmapheresis (DFPP) took place. Kidney transplantation was cancelled in three patients because of rebound to high level of anti-A or anti-B antibody, or appearance of T cell antibody after immunoadsorption.

ABO Blood-Group System↗

PubMedDate not supplied

Non-heparin hemodialysis with oral administration of newly developed antiplatelet agent.

Non-heparin hemodialysis (HD) was successfully done in anuric dogs with the oral administration of a newly developed antiplatelet agent, 4-cyano-5,5-bis(4-methoxyphenyl)-4-pentenoic acid, (E5510, Eisai Pharmaceutical Co., Japan). In the current study, the antithrombotic effect of E5510 during HD was investigated. Eleven mongrel dogs with bilateral ureteral ligation were given 0.1 mg/kg of E5510 orally 1 hr before undergoing 4 hr HD using hollow fiber dialyzers, (PMMA 5, regenerated cellulose 6) without heparin and under general anesthesia. Blood samples were taken before the administration of E5510 and before and 1, 2, 3, and 4 hr after starting HD; blood counts, hematocrits, blood chemistries, and plasma thromboxane levels (TxB2) were examined. Platelet aggregation, activated clotting times (ACT), and activated partial thrombin times (APTT) were also measured, and sequential plasma E5510 concentrations were determined. In 10 of 11 anuric dogs, non-heparin HD was successfully done with minimal clotting in the dialyzer and drip chambers. The maximum aggregation rate was depressed to less than 20% of the initial value throughout HD. Plasma TxB2 concentration was depressed, and ACT and APTT were mildly, but not significantly prolonged. Neither hemorrhagic complications nor other side effects of E5510 were observed.

Administration, Oral↗

PubMedDate not supplied

Difference in beta 2-microglobulin removal between cellulosic and synthetic polymer membrane dialyzers.

Several kinds of dialyzers, with highly permeable membranes (HPM), have been designed to specifically remove beta 2-microglobulin (BMG). To clarify their solute transport characteristics, nine types of HPM dialyzers were evaluated during in vivo and in vitro studies using human plasma and aqueous solutions. No BMG membrane adsorption and/or plugging was seen with cellulosic membrane dialyzers during in vitro experiments using human plasma. On the other hand, all synthetic polymer membrane dialyzers had adsorptive properties, and in a dialyzer with a polymethylmethacrylate membrane, a large amount of BMG was removed by adsorption alone. Dialyzers with cellulose triacetate and polyacrylonitril membranes showed higher values of BMG diffusive dialysance (greater than 20 ml/min) and sieving coefficient (greater than 0.9). From in vitro experiments using an aqueous solution containing several solutes with relatively small or middle molecular weights, all HPM dialyzers had a higher overall mass transfer coefficient than any conventional membrane dialyzer.

Blood Flow Velocity↗

PubMedDate not supplied

Forty-eight hour liver preservation using an artificial blood substitute.

Forty-eight hour hypothermic continuous perfusion preservation was attempted using a perfusion technique with an artificial blood substitute, a pyridoxylated hemoglobin-polyoxyethylene conjugated solution (stabilized hemoglobin, PHP). After preservation each of the 10 canine livers was orthotopically transplanted. Postoperative graft function was estimated by parameters such as activated clotting time (ACT), bile excretion, consciousness level, survival period, histologic findings, and adenosine triphosphoric acid (ATP) content of the perfused liver. Four of ten livers displayed good function, with bile excreted immediately after revascularization, and animal survival for over 24 hr. Cellular structure of the liver was well maintained, although atrophy of the hepatocytes and swelling of the mitochondria were seen. PHP solution is therefore considered suitable as a perfusate for long-term liver preservation.

Animals↗

PubMedDate not supplied

Superiority of selective bolus infusion and simultaneous rapid removal of anticancer agents by charcoal hemoperfusion in cancer treatment.

This report presents the clinical effectiveness of multidisciplinary therapy consisting of intraarterial selective chemotherapy, combined with radiofrequency regional hyperthermia (RFRH) in advanced cancer patients. Patients were categorized into the following therapeutic groups: Group I: RFRH without intraarterial chemotherapy. Group II: Intraarterial infusion of a standard dose of Mitomycin C (MMC) and 5Fu. Group III: RFRH combined with intraarterial chemotherapy as in Group II. Group IV: RFRH combined with a large intraarterial infusion of MMC or Adriamycin (ADM) during charcoal hemoperfusion. Clinical effectiveness in terms of more than 50% tumor size reduction was achieved in 9% in Group I, 0% in Group II, 25% in Group III and 55% in Group IV, respectively. In Group IV, several side effects were observed but were not serious, despite the lethal dose of drug administered. These results suggest that RFRH combined with selective infusion chemotherapy, especially when large doses are administered during charcoal hemoperfusion, is a valuable treatment for advanced cancer patients.

Adolescent↗

PubMedDate not supplied