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Biomedical subjects

S Eguchi

Publications and source records attributed to S Eguchi.

At least 127 records · Page 7Linked to original sources
PubMed1996

Is a bioprosthesis preferable in tricuspid valve replacement?

We reviewed clinical data on 29 patients (17 acquired disease and 12 congenital disease) who underwent tricuspid valve replacement using a Carpentier-Edwards porcine valve or a St. Jude Medical valve at Niigata University Hospital between January 1978 and October 1995, and analyzed risks related to the outcome. Age ranged from 8 to 62 years, and 17 females were included. New York Heart Association functional class was IV in 9 patients (31%). Previous valve surgery had been performed in 10 patients (34%). An urgent surgery was required in 4 patients and simultaneous mitral (with aortic) valve replacement in 13 (45%). Mean follow-up period was 6.7 years. Hospital mortality occurred in 5 patients (17.2%) and all of them had acquired valvular diseases with functional class IV. There were 6 late deaths and none of them related to the tricuspid prosthesis. Nonfatal morbidity occurred in 2 patients (a thrombosed valve and a chronic hemolytic anemia) with a St. Jude valve. Late functional class was I or II in all patients except 3 with severe left-ventricular dysfunction or bioprosthetic failure. Late postoperative echocardiographic examination showed moderate tricuspid stenosis or regurgitation in 3 patients with a Carpentier-Edwards valve. By the Kaplan-Meier method, functional class (P < 0.01) and baseline diseases (p < 0.05) were found to affect probability of freedom from cardiac- and/or valve-related mortality including hospital death. In conclusion, the present study indicates that similarly good outcome would be expected whether using a St. Jude Medical valve or a Carpentier-Edwards porcine valve, and that both functional class IV and combined acquired valvular disease are risk factors for mortality after tricuspid valve replacement. Patient-specific selection of the prosthesis would be preferable in tricuspid valve replacement.

Adolescent↗
PubMed1996

Angiotensin II type 2 receptor inhibits cell proliferation and activates tyrosine phosphatase.

The angiotensin II type 2 (AT2) receptor inhibits basic fibroblast growth factor-induced proliferation of R3T3 fibroblast cells and transiently stimulates a vanadate-sensitive phosphotyrosine phosphatase, strongly suggesting that AT2 is a mitogen inhibitor. We generated AT2 gene-null mice that showed increased blood pressure, indicating the hypotensive action of AT2. However, inhibition of renomedullary AT2 by selective antagonists, as reported by Sassard and associates, show that AT2 suppresses pressure natriuresis. Thus, both AT1 and AT2 work in the direction of sodium retention, suggesting a unique role for angiotensin II in the kidney in terms of blood pressure regulation and sodium metabolism.

Angiotensin II↗
PubMed1996

Spontaneous regression of peripheral pulmonary artery stenosis in Williams syndrome.

An infant girl diagnosed with multiple peripheral pulmonary artery stenosis and Williams syndrome was followed-up for 17 years. Three cardiac catheterizations performed over the follow-up period showed that spontaneous gradual regression of the stenosis occurred with time. The initial systolic pressure gradient of 77-79 mmHg at the stenoses had decreased to 23-29 mmHg when measured at 17 years of age. Contrary to the progressive nature of systemic artery stenosis in Williams syndrome, peripheral pulmonary artery stenosis appears to have the capacity for spontaneous improvement. Careful consideration is required to determine the indications for interventional catheterization for the dilation of peripheral pulmonary artery stenosis in cases of Williams syndrome.

Constriction, Pathologic↗
PubMed1996

Induction of right ventricular hypertrophy in neonatal guinea pigs by monocrotaline.

The purpose of this study was to develop an experimental model of neonatal right ventricular hypertrophy which was similar to human congenital heart disease associated with pulmonary hypertension. Monocrotaline (200 mg/kg), a pyrrolizidine alkaloid, was injected into neonatal Hartley guinea pigs on the day of delivery. The occurrence of pulmonary hypertension and right ventricular hypertrophy was confirmed by pressure studies and a determination of the right ventricular wet weight and myocyte diameter on the seventh day after delivery. Right ventricular systolic pressure was significantly increased at 7 days after monocrotaline treatment compared with the untreated control group. The ratio of right ventricular systolic pressure to left ventricular systolic pressure, an indicator of pulmonary hypertension, was significantly elevated from 0.32 +/- 0.02 in the controls to 0.59 +/- 0.03 in the monocrotaline group. Right ventricular wet weight was also significantly increased, indicating right ventricular hypertrophy. The diameter of cardiac myocytes was significantly increased in the right ventricle, and was decreased in the left ventricle and interventricular septum in the monocrotaline group. Neonatal guinea pigs developed pulmonary hypertension and marked right ventricular hypertrophy within 1 week after treatment with monocrotaline. This simple experimental model may have features similar to those of human congenital heart disease associated with pulmonary hypertension.

Animals↗
PubMed1996

Right ventricular systolic performance before and after surgery for tricuspid regurgitation associated with mitral stenosis.

The reversibility of right ventricular function in patients with mitral stenosis associated with secondary tricuspid regurgitation (TR) is as yet undetermined. We assessed the right ventricular systolic performance by cardiac catheterization before and 19 months after surgery in 18 patients who underwent DeVega's tricuspid annuloplasty plus mitral valve replacement (MS plus TR group) and in 9 with mitral valve replacement for isolated mitral stenosis (MS group). After surgery, the right ventricular systolic pressure decreased significantly in both groups (both p < 0.01). In the MS plus TR group, the postoperative right ventricular end-diastolic and end-systolic volume indices (RVEDVI and RVESVI, respectively) were significantly decreased compared with the respective preoperative values (both p < 0.001). No significant difference was noted between the groups with regard to the right ventricular peak-systolic pressure/end-systolic volume index ratio (RVPSP/ESVI) either before or after surgery. Various left ventricular indices were comparable between the groups both before and after surgery. Linear regression analysis revealed significant correlations between RVEDVI and the RVPSP/ESVI, and between RVPSP and the RVPSP/ESVI both before and after surgery. These results indicate that right ventricular systolic performance in patients with MS plus secondary TR became comparable to those that in patients with isolated MS after surgery, and that this was probably due to nearly equivalent right ventricular contractility before surgery.

Adult↗
PubMed1996

[Open heart surgery in patients with systemic diseases requiring steroid treatment].

Our surgical experiences in 9 patients who required steroid treatment for systemic diseases before, during and after the open heart surgery were reviewed. Subjects included 3 patients with systemic lupus erythematodes, 3 with aortitis syndrome, 1 with Behçet disease and 1 with rheumatoid arthritis. Cardiovascular lesion was aortic valve regurgitation in 2, Stanford A aortic dissection in 1 and ischemic heart disease in 3 patients. Duration of morbidity for systemic diseases before the surgery ranged between 0 nd 102 months, with a mean of 36 months. Steroid treatment was continued for 4 to 216 months (mean 70+/-76 months) before the surgery at a dose of 5-40 mg per day for conversion into prednisolone. In principal, methylprednisolone was given during the surgery, and the prednisolone was given at a dose of 20-140 mg per day on the day of operation or on the first postoperative day. Surgical procedures included a aortic valve prosthesis with Dacron cloth skirt implantation in 1 patient, surgical angioplasty of the left main coronary ostium in 1 and internal thoracic arteries grafting in 2 patients. Hospital mortality was 1 patient due to low cardiac output syndrome. Acute renal failure occurred in 2 patients with systemic lupus erythematodes, and wound complication was observed in 2 patients. In our experience, appropriate treatment for systemic diseases, timing of surgery and continuation of steroid treatment at an appropriate dose during and after the surgery seemed very important such as surgical procedure in order to prevent postoperative complications such as periprosthetic leakage and failure of anastomosis.

Aortic Arch Syndromes↗
PubMed1996

[The study on the mechanism of brain damage due to high flow and pressure during selective cerebral perfusion].

It has been reported that the high flow and pressure perfusion produced the brain damage during selective cerebral perfusion. This time we studied the mechanism of this brain damage with mock circulation. We made the mock circulation system of brain with the hard shell reservoir as cranium, and with the triple soft bags as brain tissue, involving into reservoir. We designed the control group that intracranial pressure (ICP) was 0 mmHg at pump off, and the increasing intracranial pressure (IICP) group that ICP was 10 mmHg at pump off. We measured the flow-pressure relationship in the control and IICP group, and then stenosis in outflow. In results, the flow and pressure in both the inflow and outflow side increased significantly (p < 0.001) in control groups, as pump flow increased. The changes of the flow and pressure in IICP group showed a same tendency to the control group. Moreover, both the inflow volume into bag and the outflow volume from bag decreased as pump flow increased stepwisely. The pressure in both inflow and outflow side increased significantly and the volume of the inflow side in IICP group showed a tendency to decrease, compared with the control. The stenosis in the outflow side produced the significant increase in the pressure of both inflow and outflow side, and intracranium, with the same pump flow as the control without stenosis. In conclusion, the high flow perfusion produced the increase of the several pressure in intracranial and extracranial vessels. Moreover, the high flow perfusion produced the decrease of the intracranial blood volume cerebral blood flow. The high flow perfusion does not necessarily contribute to the cerebral tissue perfusion. The stenosis at the side of venous return produced relative high perfusion. This result suggests that the venous return should be taken care of during the selective cerebral perfusion.

Blood Pressure↗
PubMed1996

Blalock-Taussig operation with an assist of venovenous extracorporeal membrane oxygenation.

Three infants with congenital cyanotic heart disease encountered severe hypoxemia during a Blalock-Taussig shunt procedure using a right thoracotomy approach. Pericardiotomy was performed and venovenous extracorporeal membrane oxygenation was instituted using right atrial canulation. The shunt procedure was completed with good oxygenation and hemodynamic stability in all cases. Venovenous extracorporeal membrane oxygenation can be easily established in the right thorax, and is an effective support technique for unexpected hypoxemia encountered during systemic-to-pulmonary artery shunt operations.

Anastomosis, Surgical↗
PubMed1996

Clinical experience with a porcine hepatocyte-based liver support system.

UNLABELLED: The only clinically proven effective treatment of fulminant hepatic failure (FHF) is orthotopic liver transplant (OLT). However, many patients die before an organ becomes available. Thus, there is a need for development of an extracorporeal liver support system to "bridge" these patients either to OLT or spontaneous recovery. We developed a bioartificial liver (BAL) based on plasma perfusion through a circuit of a hollow-fiber cartridge seeded with matrix-anchored porcine hepatocytes to treat patients with severe acute liver failure. Two groups of patients were studied. Group 1 (n = 12): patients with FHF. All patients were successfully "bridged" to OLT. "Bridge" time to OLT was 21-96 hr (mean: 39.3 hr). All patients were discharged neurologically intact. Reversal of decerebration was noted in all 11 deep stage 4 coma patients. There was reduction in intracranial pressure (ICP mmHg, 18.2 +/- 2.2 to 8.5 +/- 1.2; p < 0.004) and increase in cerebral perfusion pressure (CPP mmHg, 71.1 +/- 4.0 to 84.7 +/- 2.6; p < 0.006). Laboratory values pre- and post-BAL treatment: glucose (mg/dl) 122 +/- 11 to 183 +/- 21, p < 0.002; ammonia (mumol/l) 155.6 +/- 13.2 to 121.6 +/- 9.5, p < 0.02; total bilirubin (mg/dl) 21.6 +/- 2.8 to 18.2 +/- 2.2, p < 0.001; PT (sec) 23.2 +/- 1.7 to 21.9 +/- 1.0, p < 0.3. Group II (n = 8): patients with chronic liver failure experiencing acute exacerbation. Two patients survived and later underwent OLT. Six patients (not OLT candidates) died 1-14 days after last BAL treatment. Laboratory values pre- and post-treatment: ammonia (mumol/l) 201 +/- 47 to 143 +/- 25, p < 0.06; total bilirubin (mg/dl) 22.8 +/- 5.2 to 19.5 +/- 4.4, p < 0.01; PT (sec) 22.5 +/- 2.0 to 21.8 +/- 1.1, p < 0.6. CONCLUSION: our clinical experience with the BAL suggests that it may serve as "bridge" to OLT in patients with FHF primarily by reversing intracranial hypertension, but it is not a substitute for OLT in patients with end-stage liver disease who are non-transplant candidates.

Adolescent↗
PubMed1995

Long-term survival of cardiac allografts in rats treated before and after surgery with monoclonal antibody to CD2.

The rejection of a transplanted allograft is dependent on T cell activation, which requires T cell receptor engagement by antigen and costimulatory signals delivered by T cell surface molecules such as CD2. Anti-CD2 mAbs have been shown to suppress cell-mediated immunity. The effects of anti-CD2 mAbs OX34 and OX54 on rejection of BN (RT1n) rat hearts transplanted heterotopically to LEW (RT1l) rats were investigated. Administration of OX34 (7 mg/kg/day i.p.), either for 3 consecutive days immediately before or 8 consecutive days immediately after transplantation induced indefinite allograft survival (median survival time: 7, > 150, and > 150 days for control, preoperative treatment, and postoperative treatment, respectively). In contrast, pre- or postoperative treatment with OX54 (40 mg/kg/day) prolonged median survival time to only 28 and 11 days, respectively. Administration of OX34 or OX54 to naive rats induced a transient depletion of T cells in the peripheral immune organs. In vitro studies revealed that whereas OX54 had no effect on the allogeneic mixed lymphocyte reaction, OX34 partially inhibited both the allogeneic mixed lymphocyte reaction, in an IL-2-reversible manner, and T cell proliferation in response to immobilized mAb to either the T cell receptor or CD3. OX34-treated rats in which the cardiac allograft had survived > 100 days accepted a second heart from the donor strain. Treatment with OX34 induced an alloantigen-unresponsive state in T cells. These results suggest that treatment with an appropriate anti-CD2 mAb, especially postoperatively, may prove an effective approach for preventing cardiac allograft rejection.

Animals↗
PubMed1995

Pharmacokinetic parameter estimations by minimum relative entropy method.

For estimating pharmacokinetic parameters, we introduce the minimum relative entropy (MRE) method and compare its performance with least squares methods. There are several variants of least squares, such as ordinary least squares (OLS), weighted least squares, and iteratively reweighted least squares. In addition to these traditional methods, even extended least squares (ELS), a relatively new approach to nonlinear regression analysis, can be regarded as a variant of least squares. These methods are different from each other in their manner of handling weights. It has been recognized that least squares methods with an inadequate weighting scheme may cause misleading results (the "choice of weights" problem). Although least squares with uniform weights, i.e., OLS, is rarely used in pharmacokinetic analysis, it offers the principle of least squares. The objective function of OLS can be regarded as a distance between observed and theoretical pharmacokinetic values on the Euclidean space RN, where N is the number of observations. Thus OLS produces its estimates by minimizing the Euclidean distance. On the other hand, MRE works by minimizing the relative entropy which expresses discrepancy between two probability densities. Because pharmacokinetic functions are not density function in general, we use a particular form of the relative entropy whose domain is extended to the space of all positive functions. MRE never assumes any distribution of errors involved in observations. Thus, it can be a possible solution to the choice of weights problem. Moreover, since the mathematical form of the relative entropy, i.e., an expectation of the log-ratio of two probability density functions, is different from that of a usual Euclidean distance, the behavior of MRE may be different from those of least squares methods. To clarify the behavior of MRE, we have compared the performance of MRE with those of ELS and OLS by carrying out an intensive simulation study, where four pharmaco-kinetic models (mono- or biexponential, Bateman, Michaelis-Menten) and several variance models for distribution of observation errors are employed. The relative precision of each method was investigated by examining the absolute deviation of each individual parameter estimate from the known value. OLS is the best method and MRE is not a good one when the actual observation error magnitude conforms to the assumption of OLS, that is, error variance is constant, but OLS always behaves poorly with the other variance models. On the other hand, MRE performs better than ELS and OLS when the variance of observation is proportional to its mean. In contrast, ELS is superior to MRE and OLS when the standard deviation of observation is proportional to its mean. In either case the difference between MRE and ELS is relatively small. Generally, the performance of MRE is comparable to that of ELS. Thus MRE provides as reliable a method as ELS for estimating pharmacokinetic parameters.

Humans↗
PubMed1995

Nonselective ETA/ETB receptor antagonist blocks proliferation of rat vascular smooth muscle cells after balloon angioplasty.

To elucidate the role of endothelin receptor subtypes in the abnormal proliferation of vascular smooth muscle cells (VSMC) associated with vascular injury, we have investigated the effects of a novel and potent nonselective ETA/ETB receptor antagonist (TAK-044) on the proliferation of rat VSMC in vitro and in vivo. TAK-044 dose-dependently inhibited DNA synthesis stimulated by 10(-7) M ET-1 in cultured rat VSMC from the late passage with the approximate IC50 of 6 x 10(-8) M. After balloon angioplasty, the neointimal lesion in the injured carotid arteries in the TAK-044-treated group (0.052 +/- 0.014 mm2) was significantly (p < 0.05) decreased compared to that in control group (0.26 +/- 0.045 mm2), while the medial surface area was not affected. The intima/media ratio in the TAK-044 group (31 +/- 6%) also significantly (p < 0.05) decreased from that of the control group (148 +/- 25%). Our data suggest that nonselective ETA/ETB receptor antagonists may be therapeutic potential for prevention against the intimal thickening associated with vascular injury.

Angioplasty, Balloon↗
PubMed1995

Non-contact, two-dimensional measurement of tissue circulation in choroid and optic nerve head using laser speckle phenomenon.

A new apparatus has been developed using the laser speckle phenomenon for non-contact, two-dimensional analysis of tissue circulation in the choroid and optic nerve head (ONH). The fundus was illuminated by a diode laser spot and its image speckle was detected by an image sensor. The difference between the average of the speckle intensity (Imean) and the speckle intensity for successive scannings was calculated, and the ratio of Imean to this difference was defined as normalized blur (NB), which is a quantitative index of blood velocity. The results were displayed on color graphic monitors showing the two-dimensional variation of the NB level in the measurement field. In the rabbit, this apparatus was used to study the relationship between the results of NB measurement and the choroidal blood flow determined by the microsphere technique, the relationship between NB obtained from the ONH tissue free of visible surface vessels and the ocular perfusion pressure (OPP) after a lethal injection of pentobarital, and the effect of intraocular pressure (IOP) on the NB in the choroid or in the ONH. A stepwise reduction in the OPP was introduced by elevating the IOP manometrically. The relative decrease in the average NB over the field measured, NBav, in the choroid with the reduction in OPP showed a significant correlation with the relative change in the blood flow rate determined using the microsphere technique (r = 0.60, P < 0.001). NBav in the ONH had a good correlation with the OPP after a lethal injection of pentobarbital (r = 0.98, P < 0.001). NBav in the choroid decreased with reduction in the OPP. Although NBav in the ONH was little affected by OPP change when OPP was above 40 mmHg, at OPP levels below 40 mmHg, NBav in the ONH decreased along with a reduction in the OPP. These results suggest that by using the present apparatus, the blood velocity in the choroid or ONH under various conditions can be studied non-invasively in the living eye.

Animals↗
PubMed1995

Surgery for cavoatrial extension of malignant tumors.

Surgical management for cavoatrial involvement of malignant tumors and its outcome is reported on for 6 patients; their age ranged from 55 to 79 years and 5 were male and 1 female. The basic disease was renal cell carcinoma in 5 cases and adrenal leiomyosarcoma in 1. Intracaval tumor extension was diagnosed by computed tomography, magnet resonance imaging, digital subtraction angiography, and echocardiography. The tumor was resected together with adherant vena cava and invaded right-atrial wall, using cardiopulmonary bypass and normo- or mild-hypothermia in 5 patients. The caval defect needed to be reconstructed with a slit GORE-TEX vascular prosthesis in 3 patients. In all patients the tumor resections were successful and without major complications. All patients survived and are well from 4 to 52 months after the surgery. It is concluded that such cavoatrial extensions of malignant tumors can be safely and accurately resected with the aid of cardiopulmonary bypass, with favorable early and late outcomes in patients who have no distant metastatic lesions.

Adrenal Gland Neoplasms↗
PubMed1995

Closure of isolated ventricular septal defect with detachment of the tricuspid valve.

Detachment of the septal leaflet of the tricuspid valve is an alternative technique for obtaining complete visualization of a perimembranous ventricular septal defect (VSD) in cases where the VSD is obscured by the chordae tendineae or a pouch formation of the septal leaflet. This method presents theoretical concerns because it has the potential for causing postoperative valvular insufficiency. We therefore evaluated valvular function in patients who underwent VSD closure with detachment of the tricuspid valve. In a consecutive series of 153 patients who underwent VSD closure using a transatrial approach, 13 had incision of the tricuspid valve. Follow-up echocardiographic studies were performed on these patients at least 1 year following operation. There were no operative deaths. Color Doppler echocardiography revealed no residual shunt in any of these patients. Ten patients had no evidence of tricuspid stenosis or regurgitation. One patient had trivial tricuspid regurgitation. Moderate tricuspid regurgitation was observed in two patients of these, one patient was a small infant who had a VSD complicated by pulmonary hypertension. The other patient had a VSD with a mitral cleft, pulmonary hypertension, and Down's syndrome. The incised tricuspid valve was resuspended by solely running sutures. In conclusion, detachment of the tricuspid valve is a safe and useful method for adequate exposure of a VSD. However, this method should be avoided in patients with Down's syndrome and in small infants. Furthermore, repair of the incised valve should not be performed using only running sutures.

Adolescent↗