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Biomedical subjects

T Yuda

Publications and source records attributed to T Yuda.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Perforation and localized dissection of the left common iliac artery during the modified Bentall procedure: a case report].

We performed the modified Bentall procedure for annuloaortic ectasia in a 41-year-old man with Marfan's syndrome. Approximately 15 minutes after initiation of cardiopulmonary bypass with an arterial delivery via the left common femoral artery, perfusion volume gradually decreased and the abdomen of the patient was distended. Retrograde dissection was strongly suggested. Perforation and localized dissection of the left common iliac artery were recognized. Following repair of the lesion, the modified Bentall operation was carried out. Postoperative course was uneventful. The patient has been well for 22 months after the operation.

Adult↗
PubMed1996

[Surgical results of valve replacement with porcine bioprostheses].

We evaluated the 80 cases of porcine valve replacement, accomplished between April 1975 and December 1980. There were 48 males and 32 females aged between 16 and 60 years old with a mean of 37.4 +/- 11.4. Ten patients underwent aortic valve replacement (AVR), 63 mitral valve (MVR), and 7 AVR plus MVR. Twenty-seven Hancock valves (H) were implanted in aortic (3) and mitral (24) position and 61 Carpentier-Edwards valves (CE) were used in aortic (14), mitral (46), and tricuspid (1) position. The mean duration of follow-up was 9.3 years (0.2-19.2 years) and cumulative follow-up was 747.2 patient years (py). The late mortality was 3.3%/py (25 patients). Actuarial survival rates for all patients at 10 and 15 years were 67%, and 49% respectively. The linearized rates (LR) of structural valve deterioration (SVD) was 7.0%/py. The freedom from SVD for all patients at 10, and 15 years were 47.1%, and 12.4% respectively. There were no differences of free rates of SVD between H and CE. between valve sites implated, and among age at operation. The incidence of occurrence of SVD was gradually increased 6 years after operation. The LR of thromboembolism (TE), anticoagulant-related hemorrhage (ACH), prosthetic valve endocarditis (PVE), nonfunctional valve dysfunction (NVD), and reoperation (RO) were 0.7%/py, 0.1%/py, 0.3%/py, 0.1%/py and 7.4%/py, respectively. The freedom from TE, ACH, PVE, NVD, and RO for all patients at 15 years were 91.3%, 98.1%, 95.6%, 80%, and 6.5%, respectively. The surgical results of glutaraldehyde-preserved porcine bioprostheses was excellent during the first 5 years after operation. A high incidence of SVD has been occurred thereafter. According the indication for valve replacement with bioprotheses is now strictly limited for elderly, child bearing female case, contraindition for therapy of anticoagulants, and some social condition.

Adolescent↗
PubMed1995

Targetability of novel immunoliposomes modified with amphipathic poly(ethylene glycol)s conjugated at their distal terminals to monoclonal antibodies.

Distearoyl-N-(3-carboxypropionoyl poly(ethylene glycol) succinyl)phosphatidylethanolamine (DSPE-PEG-COOH) was newly synthesized and used to prepare novel immunoliposomes carrying monoclonal antibodies at the distal ends of the PEG chains (Type C). Liposomes were prepared from egg phosphatidylcholine (ePC) and cholesterol (CH) (2;1, m/m) containing 6 mol% of DSPE-PEG-COOH, and a monoclonal IgG antibody, 34A, which is highly specific to pulmonary endothelial cells, was conjugated to the carboxyl groups of DSPE-PEG-COOH to give various amounts of antibody molecules per liposome. Other immunoliposomes with PEG coating (Type B) or without PEG coating (an earlier type of immunoliposome, Type A) were prepared for comparison. The average molecular weight of PEG in Type B or C immunoliposomes was 2000. Type B and Type C liposomes without antibodies showed prolonged circulation time and reduced reticulo-endothelial system (RES) uptake owing to the presence of PEG. These three different types of 34A-immunoliposomes with 30-35 antibody molecules per vesicle were injected into mice to test the immunotargetability to the lung. The efficiency of lung binding of 34A-Type B was one-half of that of 34A-Type A, though a large amount of 34A-Type B remained in the blood circulation for a long time, suggesting that the steric hindrance of PEG chains reduced not only the immunospecific antibody-antigen binding, but also the RES uptake. The degree of lung binding of 34A-Type C was about 1.3-fold higher than that of 34A-Type A, indicating that recognition by the antibodies attached to the PEG terminal was not sterically hindered and that the free PEG (i.e., that not carrying antibody) was effective in increasing the blood concentration of immunoliposomes by enabling them to evade RES uptake. The latter phenomenon was confirmed by using nonspecific antibody-Type C immunoliposomes (14-Type C), which showed a high blood level for a long time. Our approach provides a simple means of conjugating antibodies directly to the distal end of PEG which is already bound to the liposome membrane, and should contribute to the development of superior targetable drug delivery vehicles for use in diagnostics and therapy.

Animals↗
PubMed1994

Enhanced delivery and antitumor activity of doxorubicin using long-circulating thermosensitive liposomes containing amphipathic polyethylene glycol in combination with local hyperthermia.

Enhanced delivery of doxorubicin (DXR) to a solid tumor subjected to local hyperthermia was achieved by using long-circulating, thermosensitive liposomes (TSL) composed of dipalmitoyl phosphatidylcholine (DPPC)/distearoyl phosphatidylcholine (DSPC) (9:1, m/m) and 3 mol% amphipathic polyethylene glycol (PEG) in colon 26-bearing mice. Inclusion of 3 mol% of distearoyl phosphatidylethanolamine derivatives of PEG (DSPE-PEG, amphipathic PEG) with a mean molecular weight of 1000 or 5000 in DPPC/DSPC liposomes resulted in decreased reticuloendothelial system (RES) uptake and a concomitant prolongation of circulation time, affording sustained increased blood levels of the liposomes. Concomitantly, DXR levels in blood were also kept high over a long period. The presence of amphipathic PEG did not interfere with the encapsulation of DXR by the pH gradient method (> 90% trapping efficiency) or with the temperature-dependent drug release from the liposomes. The optimal size of these liposomes was 180-200 nm in mean diameter for thermosensitive drug release and prolonged circulation time. The DXR levels in the tumor after injection of long-circulating TSL (DXR-PEG1000TSL or DXR-PEG5000TSL, at a dose of 5 mg DXR/kg) with local hyperthermia were much higher than after treatment with DXR-TSL lacking PEG or with free DXR, reaching 7.0-8.5 DXR micrograms/g tumor (approximately 2 times or 6 times higher than that of DXR-TSL or free DXR, respectively). Furthermore, the combination of DXR-PEGTSL and hyperthermia effectively retarded tumor growth and increased survival time.(ABSTRACT TRUNCATED AT 250 WORDS)

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1994

[Nonsurgical retrieval of intravascular catheter fragments].

The incidence of catheter fragment induced by iatrogenic accident has been increasing because of frequent use of intravenous catheters and catheterization in daily practice. Migrated intravascular fragments from broken catheters were retrieved transcutaneously in four cases. All fragments were removed safely using biotome, multipurpose grasping forceps and basket catheter. But in a case which the fragment was lodged in the pulmonary artery, retrieval was not easy and it took many times. Fragments lodged in the right ventricle and in the pulmonary artery cause many complications including deaths. So broken fragments should be removed as soon as possible, before it migrated to there.

Adolescent↗
PubMed1993

[Surgery for ventricular septal defect with aortic regurgitation].

Twenty-two patients (mean age of 12.9 years) with ventricular septal defect (VSD) associated with aortic regurgitation (AR) were treated surgically. Sixteen patients had subpulmonic VSD and six had infracristal VSD. Fourteen patients with subpulmonic VSD underwent VSD closure alone. VSD was closed by pulling up the inferior rim to the pulmonary valve thus support the prolapse aortic cusp. AR improved in two and has remained stable in eleven for 0.5 to 12.7 years (mean 4.4 years). Aortic valve replacement (AVR) was necessary in an adult patient later. Plication of the aortic valve was effective in a young patient but ineffective in an adult patient. In infracristal VSD, AVR was necessary in two adult patients. In a young patient, AR improved by plication. Direct VSD closure ceased progression of AR in three patients. The long-term follow-up shows that VSD closure with our technique has been sufficient to arrest progression of AR in subpulmonic VSD. Early closure of VSD should be emphasized to prevent aortic valve prolapse and regurgitation.

Adolescent↗
PubMed1992

Prolonged circulation time in vivo of large unilamellar liposomes composed of distearoyl phosphatidylcholine and cholesterol containing amphipathic poly(ethylene glycol).

The effect of poly(ethylene glycol) (PEG) on the circulation time of liposomes in mice was examined by employing amphipathic PEGs (phosphatidylethanolamine (PE) derivatives of PEG) with average molecular weights of 1000, 2000, 5000 and 12,000. The activity of dioleoyl phosphatidylethanolamine-PEG (DOPE-PEG) in prolonging the circulation time of egg phosphatidylcholine/cholesterol large unilamellar liposomes (ePC/CH LUVs) (200 nm) was proportional to the molecular weight of PEG, i.e., 12000 = 5000 greater than 2000 greater than 1000. On the other hand, inclusion of distearoylphosphatidylethanolamine-PEG (DSPE-PEG) or dipalmitoyl-phosphatidylethanolamine-PEG (DPPE-PEG) of low molecular weight such as 1000 and 2000 in distearoylphosphatidylcholine (DSPC)/CH LUVs or dipalmitoyl phosphatidylcholine (DPPC)/CH LUVs effectively increased their blood circulation time. At least 3 mol% of amphipathic PEG in liposomes was required for activity. Addition of CH, which has a bilayer-tightening effect, to DSPC/CH/DSPE-PEG2000 LUVs further increased the blood residence time. A size of less than 300 nm was essential for prolonging the residence time of amphipathic PEG-containing liposomes in blood. DSPC/CH/DSPE-PEG2000 LUVs (1:1:0.13, m/m) containing 6 mol% of PEG and 200 nm in diameter remained in the circulation for over 24 h after injection and may be clinically useful for sustained release of an entrapped drug in the bloodstream and for drug accumulation in solid tumors.

Animals↗
PubMed1992

Effects of intraaortic balloon position on renal artery blood flow.

Debate continues over what happens to renal blood flow when intraaortic balloons are adjacent to the renal arteries. Fourteen dogs were prepared by implanting instruments to measure heart rate; right atrial, pulmonary arterial, carotid arterial, and femoral arterial pressures; cardiac index; mixed venous oxygen saturation; urine output; and left and right renal blood flows. A 12-mL intraaortic balloon was inserted through the left (n = 9) or right (n = 5) femoral artery. The position of the balloon was randomized so that it was initially placed in either the control (thoracic) or renal position (at the level of the renal arteries). Intraaortic balloon pumping was performed for 4 hours in each position. In 8 dogs, at least one of the renal arteries had partial occlusion, 23% to 98% decrease in flow (mean decrease, 66%), while the intraaortic balloon was in the renal position. An intraaortic balloon in the renal position results in lower renal blood flow as well as a high risk (57%) of selective renal artery occlusion. Decreased renal blood flow is not apparent using conventional monitoring, as hemodynamics do not change.

Animals↗
PubMed1991

Surgical treatment of abdominal aortic aneurysm in the high-risk patient.

In an attempt to define the preoperative risk factors that predictably influence mortality after aneurysmectomy, this study reviews the surgical management of abdominal aortic aneurysms in a series of 110 consecutive patients who underwent elective resection. The preoperative risks to be added to the present study included pulmonary insufficiency, renal dysfunction, advanced age of over 80 years, ischemic heart disease, and associated other diseases such as thoracic aneurysms, atherosclerosis of the limbs and malignant tumors. Forty-six patients had one of these risk factors (one-risk group), 17 had two (two-risk group), and 9 had three (three-risk group). The operative mortality rates were 4.2 per cent for the high-risk patients and 0 per cent for the patients at no risk. As the number of risk factors increased, aneurysm repair was associated with an increased operative mortality; being 2.2 per cent in the one-risk group, 5.9 per cent in the two-risk group and 11.1 per cent in the three-risk group. The common risk factor in patients who died after aneurysmectomy was pulmonary insufficiency which induced prolonged periods of assisted ventilation. Thus, the optimal management of high-risk patients, particularly those with pulmonary insufficiency, may reduce the mortality after aneurysmectomy.

Aged↗
PubMed1991

Effect of molecular weight in amphipathic polyethyleneglycol on prolonging the circulation time of large unilamellar liposomes.

The effect in mice of the molecular weight of polyethyleneglycol on prolonging the circulation time of large unilamellar liposomes (LUVs) was examined using four different distearoyl N-(monomethoxy polyethyleneglycol succinyl) phosphatidylethanolamines (DSPE-PEGs). The molecular weights tested were 1000, 2000, 5000 and 12000. Incorporation of 6 mol% of DSPE-PEG in LUV composed of distearoylphosphatidylcholine (DSPC) / cholesterol (CH) (1:1 in molar ratio) increased the blood circulation half-life significantly more than those without DSPE-PEG derivatives. DSPE-PEGs with molecular weights of 1000 and 2000 prolonged the circulation time of liposomes more than other DSPE-PEGs with higher molecular weights, such as 5000 and 12000. Their effects are also higher than ganglioside GM1, a well described glycolipid with this effect. DSPC/CH LUV-incorporated DSPE-PEG with a molecular weight of 2000 displayed a high concentration in the blood, approximately 40% of the dose, 6 h after the injection.

Animals↗
PubMed1991

Detection of lung rejection with indium-111-labeled lymphocytes in heterotopic rat heart-lung transplantation.

To determine if acute lung rejection after heart-lung transplantation can be detected noninvasively with indium-111-labeled (111In) lymphocytes, we studied 33 allogeneic and 18 isogeneic heterotopic heart-lung transplants in rats. Twenty-four hours after injection of isogeneic splenic 111In-lymphocytes (75 +/- 2 microCi/100 million cells), animals were scanned at 2 to 8 days after transplant (Tx). Also, percent indium uptake of the graft was determined and compared with pathologic lung changes. Between the vascular and destructive phases of lung rejection, 111In-lymphocyte uptake of lung allografts was significantly greater than isografts (p less than 0.001). Lung allografts in the alveolar phase (4-6 days after Tx) showed the most intense uptake (2.7 +/- 0.1%) of injected 111In-lymphocytes. All scintigrams of allografts from the late vascular to the early destructive phase (3-7 days after Tx) showed visualization of the lung graft (27/27 true positive, sensitivity = 100%). In contrast, lung isografts of the same period showed no pathological sign of rejection and were only rarely visualized (12/14 true negative, specificity = 86%). Lung rejection may be accurately assessed noninvasively by gamma scintigraphy with 111In-lymphocytes. This technique may prove useful in the detection of acute lung rejection in human heart-lung transplant recipients. Modification of the labeling dose chosen may further improve scan accuracy.

Abdomen↗
PubMed1991

[Nonsurgical removal of the embolized catheter fragments from the heart and great vessels].

Embolized catheter fragments in the heart and great vessels were successfully removed in seven patients by nonsurgical techniques. All procedures for the retrieval were completed without complications or difficulty using instruments such as multipurpose grasping forceps, stone basket, loopsnare and myocardial biopsy catheters. Embolized catheter fragments should be removed promptly before fatal complications develop, and can be taken off safely and simply by nonsurgical technique.

Aged↗
PubMed1991

[Total anomalous pulmonary venous connection associated with Klippel-Feil syndrome: a case report].

Klippel-Feil syndrome is characterized by congenital fusion of the cervical vertebrae. Anomalies in other organs sometimes combine. Many kinds of congenital cardiac anomalies, most frequently ventricular septal defect, considerably associate with this syndrome. Few cases of surgical corrections of cardiac anomalies with Klippel-Feil syndrome have been reported up to today. Therefore surgical problems with this syndrome have not been solved yet, completely. We have experienced a very rare case of a 18-year-old female of total anomalous pulmonary venous connection (Darling Ia type) associated with Klippel-Feil syndrome, that was repaired successfully. No difficulty in the surgical and anesthesiological management referring to the fusion of cervical vertebrae was encountered. The result of surgical correction of congenital cardiac anomalies in Klippel-Feil syndrome mainly depends on the severity of the heart disease and not on Klippel-Feil syndrome itself, as literature and the present case suggest.

Adolescent↗
PubMed1990

The necessity of reoperation for patients with Bjork-Shiley, St Jude Medical, Hancock and Carpentier-Edwards prostheses.

The purpose of this study was to determine the criteria of valve selection from the long-term results of Hancock, Carpentier-Edwards, St Jude Medical and Bjork-Shiley prostheses, taking into special account the frequency of reoperation. Reoperations on the Hancock bioprosthesis were performed on six patients for tissue leaflet disruption with an incidence of 2.2 per cent/patient-year. Reoperations on the Carpentier-Edwards bioprosthesis were performed on 24 patients for tissue leaflet disruption in 23 patients and prosthetic valve endocarditis (PVE) in one, with an incidence of 3.8 per cent/patient-year. Reoperations on the Bjork-Shiley prosthesis were performed in two patients for severe hemolysis, with an incidence of 0.32 per cent/patient-year. Reoperations on the St Jude Medical prosthesis were performed on 3 patients, for valve thrombosis in one patient, PVE in one, and hemolysis in one, with an incidence of 0.23 per cent/patient-year. The overall mortality rate was 20 per cent, or 7 patients, and the indications for reoperation affected this. Patients with primary tissue failure had a mortality rate of 10.3 per cent; those with a thrombosed valve, 0 per cent; those with hemolysis, 66.7 per cent; and those with valve infection, 100 per cent. A good chance of survival may be achieved in patients facing prosthetic valve complications by performing reoperation as soon as possible after early detection, since mortality is high following emergency reoperation and in patients with severe symptoms. Currently, we recommend mechanical prostheses for valve replacement except in patients over 70 years old and in younger patients with absolute contraindications to anticoagulative therapy.

Aged↗
PubMed1990

[Intravascular hemolysis after prosthetic valve replacement].

Two kinds of mechanical valve, St. Jude Medical (SJM) and Björk-Shiley (B-S), in patients with single valve replacement have been evaluated on a view point of intravascular hemolysis. Cases were consisted of 78 SJM and 32 B-S for the mitral and 12 SJM and 36 B-S for the aortic positions. Serum LDH, indirect bilirubin, GOT, hemoglobin levels and reticulocyte count were pursued in a given schedule, especially on the 21st postoperative day. A follow-up study on cases with abnormally high level of LDH (over 800 W.U.) at the time of hospital discharge was also performed. Paravalvular leakage detectable on the echocardiographical study was denied in all cases. The case with SJM valve replacement on the mitral position revealed a higher level of LDH, GOT and a large count of reticulocyte than those in the B-S valve. Insignificantly was found, however, in the same study with replaced valve on the aortic position. There was no correlation between the severity of hemolysis and the size of prostheses. The level of LDH, remained in high on discharge declined gradually thereafter during postoperative observation. As a whole, the result of this study supports the conventional valve selection and usage in our clinic. The patient with subclinical hemolysis after valve replacement should be placed on a schedule of close observation.

Aortic Valve↗