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Y Shimazaki

Publications and source records attributed to Y Shimazaki.

At least 19 recordsLinked to original sources
PubMed1995

Evidence that graft coronary arteriosclerosis begins in the early phase after transplantation and progresses without chronic immunoreaction. Histopathological analysis using a retransplantation model.

The histopathological features of chronic rejection and its initiation were assessed using rat heterotopic heart transplantation and retransplantation models. Fully allogeneic or minor, non-MHC antigen-mismatch heart grafts transplanted into recipient rats treated with a short course of FK506 showed long-term survival but developed graft atherosclerosis after 40 days posttransplantation. Retransplantation of allografts back into the original donor strain did not prevent graft atherosclerosis if the grafts had resided in the primary recipient for up to 5 days; residence in the primary allogeneic recipient for less than 4 days did not result in graft atherosclerosis in the secondary recipient. Short-course administration of FK506 did not affect the production of these changes. Graft coronary arteriosclerosis begins between 3 and 5 days posttransplantation and progresses without continuous allogeneic immunological drive. The present findings will provide a new means by which to approach the analysis of development of chronic allograft rejection.

Animals↗
PubMed1995

Supplement of nitric oxide attenuates neutrophil-mediated reperfusion injury.

BACKGROUND: Nitric oxide (NO) derived from the endothelial cell has been identified as a constitutive chemical mediator that regulates the function of the endothelial cell in association with neutrophil (PMN) adhesion and activation. However, its role in the pathogenesis of myocardial reperfusion injury is not clear. METHODS AND RESULTS: Fifteen isolated rat hearts were perfused with modified Krebs-Henseleit solution and subjected to 20 minutes of global and normothermic ischemia. Then the hearts were reperfused for 45 minutes with different protocols: the control (C) group was reperfused without PMNs, the P group was reperfused with PMNs, and the N group was reperfused with PMNs and nitroprusside (10(-5) mol/L). The ozone chemiluminescence method was used for direct measurement of NO in the coronary effluent during reperfusion. NO in the coronary effluent in the C group decreased at reperfusion after normoxic perfusion, and this decrease in NO continued for the first 15 minutes of reperfusion. Percentage recovery of left ventricular developed pressure and coronary flow was significantly lower in the P group than that in the N group. Also, the N group had a significantly lesser Luminol-elicited chemiluminescence of the coronary effluent and ratio of PMN adherence to myocardial vasculature compared with the P group. CONCLUSIONS: This study demonstrated directly the decrease in NO production during reperfusion and showed that supplement of NO with NO donor attenuated the injury in which PMNs were involved. The results suggest that NO plays a significant role in reperfusion injury and that supplement of NO during reperfusion appears to be useful to attenuate this injury.

Animals↗
PubMed1995

Inhibition of Na+/H+ exchanger attenuates neutrophil-mediated reperfusion injury.

BACKGROUND: The effect of Na+/H+ exchange inhibition in neutrophil-induced reperfusion injury was investigated using a new amiloride analogue, 5-methyl-N-isobutyl amiloride (MIA). METHODS: Rat neutrophils were separated using Percoll gradient. Luminol chemiluminescence intensity of isolated neutrophils was depressed by MIA in a dose-dependent manner. RESULTS: The effect of MIA on neutrophil-induced reperfusion injury was evaluated in Langendorff-perfused rat hearts subjected to 30 minutes of normothermic ischemia. Postischemic left ventricular developed pressure recovery was depressed by the reperfusion with neutrophils (60% +/- 7% to 33% +/- 26%) and was reverted by MIA pretreatment (86% +/- 17%, p < 0.05). MIA also improved percent recovery of coronary flow (51% +/- 2% to 70% +/- 13%), reduced creatine kinase (0.28 +/- 0.1 to 0.085 +/- 0.03 IU.L-1.g-1 dry wt), and lactate dehydrogenase leakage (10.6 +/- 3.8 to 5.16 +/- 1.3 IU.L-1.g-1 dry wt) significantly. The incidence of reperfusion-induced ventricular fibrillation also was reduced by MIA. CONCLUSIONS: The inhibition of Na+/H+ exchange shows a protective effect against neutrophil-induced reperfusion injury possibly by inhibiting the activation of neutrophils.

Amiloride↗
PubMed1995

Structure-activity relationship study of TXA2 receptor antagonists. 4-[2-(4-substituted phenylsulfonylamino)ethylthio]phenoxyacetic acids and related compounds.

We have recently reported that 4-[2-(4-substituted phenylsulfonylamino) ethylthio]phenoxyacetic acids and related compounds showed potent thromboxane A2 (TXA2) receptor antagonist activity. To understand how substituents affect the biological activity, the quantitative structure-activity relationship (QSAR) was analyzed by using the Hansch-Fujita method for 36 compounds, including newly synthesized compounds. The positive coefficient for pi R and FR in the results of the QSAR study suggested that a hydrophobic an sigma electron-withdrawing substituent R at the para-position of the phenylsulfonyl moiety is required to improve the activity. Further, a substituent R which is long and moderately wide, was suggested to be preferable for the activity. The positive coefficients for pi X,Y,W-COOH and sigma Q(1)-(6) may indicate that the introduction of a hydrophobic and electron-withdrawing group on the benzene ring of the phenoxy acetic acid moiety enhances the activity. The length of the W-COOH moiety may also be important. On the other hand, the effect of the presence of methylene (n = 1) was not clear.

Animals↗
PubMed1995

Osteodysplastic primordial dwarfism: a case with features of type II.

We describe a 22-month-old Japanese girl with severe microcephaly with a prominent nose and a receding chin, developmental delay, marked intrauterine and postnatal dwarfism with limb shortening and brachydactyly, and distinctive radiological changes of the skeleton. The radiological findings include hypoplasia of the short tubular bones, multiple pseudoepiphyses in the bases of the metacarpals, coxa valga, a wide pelvis with iliac flaring, thoracolumbar scoliosis, and disharmonious ossification delay. The clinical and radiological features are somewhat different from those of previously reported cases with osteodysplastic primordial dwarfism. The clinical and radiological manifestations of osteodysplastic primordial dwarfism are reviewed and compared with those in our patient.

Dwarfism↗
PubMed1992

[Thinning of ventricular septum in tetralogy of Fallot].

Cross sectional echocardiography was used to evaluate the thickness of the ventricular septum in tetralogy of Fallot (TOF). Forty-six patients with TOF and 20 patients with pseudo-truncus arteriosus underwent echocardiography during a five-year period beginning in 1984. Thicknesses of the right ventricular anterior wall (RVAWT), trabecular septum (IVST) and left ventricular posterior wall (LVPWT) were measured in end diastole on parasternal short axis view at the level of the tips of papillary muscles. The ratios of IVST to RVAWT and IVST to LVPWT were assessed. The ratio of IVST to RVAWT was 1.09 +/- 0.15 in the group aged less than 7 years (less than 7 y.o.) and 0.94 +/- 0.15 in the group aged of 7 years or more (greater than = 7 y.o.). The ratios of IVST to LVPWT were 1.10 +/- 0.14 (less than 7 y.o.) and 0.90 +/- 0.15 (greater than = 7 y.o.), respectively. Both ratios were significantly different (p less than 0.01) in the two age groups, and relative thinning of the septum was demonstrated in the older patients. It is speculated that thinning of the interventricular septum is caused by the lower systolic wall stress of the ventricular septum compared with that of the free walls, which is produced under equal systolic pressure of the two ventricles. It is suggested that this thinning is one of the factors that reduces left ventricular function after repair of TOF.

Adolescent↗
PubMed1992

Transaortic patch angioplasty for left coronary ostial stenosis in a patient with Takayasu's aortitis.

A 35-year-old woman who had left coronary ostial stenosis and aortic valve regurgitation due to Takayasu's aortitis underwent transaortic patch enlargement of the stenosed left coronary ostium in combination with aortic valve replacement. This technique may be suitable and recommendable as an alternative to aortocoronary bypass grafting or endarterectomy for coronary ostial stenosis in Takayasu's aortitis.

Adult↗
PubMed1992

An appraisal of patch enlargement of the small aortic annulus in 33 patients undergoing aortic valve replacement.

To avoid the problem of valve prosthesis/patient mismatch in the late postoperative period, we have adopted patch enlargement of the small aortic annulus in 33 patients having undergone aortic valve replacement since 1975, when the aortic annulus could not accept a large enough prosthesis. The mean age was 40 years, including 2 children aged 4. The technique of patch enlargement utilized was Nicks' method wherein the incision does not extend onto the mitral leaflet. In 31 adult patients, the aortic annulus before enlargement ranged in diameter from 18 to 24 mm with an average of 20.8 mm. After enlargement, the diameter of the annulus was 25.0 mm on average. In 2 children, the mean diameter of the annulus was enlarged from 16.5 mm to 20.5 mm. There were 2 early deaths in the initial series and 2 late deaths. Patch enlargement of the small aortic annulus is a simple, safe, and effective adjunct permitting the insertion of a valve one or two sizes larger than that which could be accommodated by the native annulus.

Adolescent↗
PubMed1992

[Phrenic nerve palsy after open heart surgery--problems in post-operative respiratory management].

We clarified the problems in respiratory management in patients with phrenic nerve palsy (PNP) after open heart surgery. From December 1988 to March 1991, 248 adult patients underwent open heart surgery with topical myocardial cooling. In these patients PNP was diagnosed in 17 patients (6.9%). Age of these patients at operation ranged from 25 to 76 years with a mean age of 57 years. 9 patients were valvular heart disease (7 were reoperation), 7 were coronary artery disease, and one patient was aortic aneurysm. PNP was diagnosed by chest roentgenogram or percutaneous phrenic nerve stimulation test (PNST). Frequency of long-term intubation (> 14 days) was higher in complete PNP patients than incomplete PNP patients. 2 patients, who were observed effort dyspnea at the time of respiratory weaning, were extubated followed by respiratory and circulatory deterioration, and were reintubated. PNP were confirmed after reintubation by PNST. These patients died of pneumonia. Another 2 patients were observed effort dyspnea during respiratory weaning, and were doubted of PNP. PNP were confirmed by PNST before extubation. After hemodynamic stabilization and respiratory physiotherapy, these patients were extubated without any trouble. One patient, who required repeated intubation, was diagnosed PNP by PNST. This patient was extubated after confirmation of improvement of PNP by follow-up PNST. The incidence of PNP was higher in patients with previous open heart surgery than without previous operation. We supposed that the dissection around the heart might be one of major cause of postoperative PNP. So, in recent 4 cases of mitral reoperation, we attempted to reach mitral valve through atrial septum with minimum dissection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Pulsed Doppler echocardiographic observation of left ventricular filling dynamics after aortic valve replacement in patients with chronic aortic regurgitation].

The 23 patients who underwent aortic valve replacement (AVR) for aortic regurgitation (AR) from 1977 to 1990 were studied with pulsed Doppler echocardiography. The patients were divided into two groups. The A group consisted of 5 patients whose end-systolic volume index (ESVI) were more than 200 ml/m2 and/or left ventricular ejection fraction (EF) were less than 0.35 before AVR. The B group consisted of 18 patients whose ESVI were less than 200 ml/m2 and EF were more than 0.35 before AVR. A Doppler volume sampler was placed at the center of mitral orifice to measure the transmitral inflow velocity after AVR (mean 28 months). Left ventricular filling dynamics were assessed by the peak velocity in the rapid filling phase (R), the peak velocity in the atrial contraction phase (A) and the ratio of A by R (A/R ratio) of mitral flow velocity pattern. The deceleration rate of early diastolic rapid inflow (DeR) determined as the slope a straight line drawn between the peak of early diastolic inflow and a point at half peak velocity on the fall side of the envelope. Result was as follows; 1) The DeR showed significant correlation with the EF (r = 0.56, p < 0.01). The DeR showed significant inverse correlation with the ESVI (r = -0.52, p < 0.05). 2) The R velocity (mean 43.9 +/- 7.9 cm/sec) in group A was significantly lower than in group B (mean 61.4 +/- 18.6 cm/sec), (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Preoperative and postoperative right ventricular function during exercise in patients with mitral stenosis.

To elucidate the effects of mitral valve surgery on right ventricular function in 11 patients with mitral stenosis, pre- and postoperative right ventricular function were quantified using gated equilibrium blood pool radionuclide ventriculography at rest and during exercise. The preoperative right ventricular ejection fraction was 39 +/- 4% at rest and 36 +/- 9% during exercise, which during exercise was lower than control values (51 +/- 5%) (p < 0.01). When the preoperative right ventricular ejection fraction was lower during exercise than at rest, postoperative right ventricular ejection fraction during exercise was lower than normal values (42 +/- 3% versus 51 +/- 5%) (p < 0.01). When the preoperative right ventricular ejection fraction did not decrease during exercise, the postoperative right ventricular ejection fraction was within normal limits during exercise (54 +/- 5%). In addition, postoperative right ventricular ejection fraction during exercise increased to normal values in patients whose preoperative right ventricular ejection fraction during exercise had been 40% or higher. Preoperative peak ejection rate was -1.81 +/- 0.19 EDV/sec at rest and -1.72 +/- 0.39 EDV/sec during exercise, which during exercise was lower than control values (-2.44 +/- 0.53 EDV/sec) (p < 0.01). Postoperatively, peak ejection rate during exercise (-2.50 +/- 0.37 EDV/sec) increased (p < 0.05) to normal levels. Preoperative peak filling rate was 1.61 +/- 0.47 EDV/sec at rest and 1.88 +/- 0.54 EDV/sec during exercise, which during exercise was lower than control values (2.58 +/- 0.62 EDV/sec) (p < 0.01). Postoperatively, peak filling rate during exercise (2.82 +/- 0.62 EDV/sec) increased (p < 0.05) to normal values in all patients. Preoperative changes in both right ventricular ejection fraction and peak ejection rate from rest to exercise inversely correlated with the preoperative pulmonary vascular resistance at rest (right ventricular ejection fraction, r = -0.79, p < 0.005; and peak ejection rate, r = -0.67, p < 0.05). In conclusion, right ventricular systolic function improved in about half of the patients with mitral stenosis, and diastolic function improved in all patients during exercise following surgery. When the preoperative pulmonary vascular resistance was elevated, the right ventricular systolic dysfunction persisted.

Adult↗
PubMed1992

Assessment of regional and transmural myocardial perfusion by means of intraoperative myocardial contrast echocardiography during coronary artery bypass grafting.

By using intraoperative myocardial contrast echocardiography, we assessed regional myocardial perfusion and transmural blood flow distribution immediately after myocardial revascularization. A total of 62 revascularized myocardial areas were studied in 31 patients undergoing coronary artery bypass grafting. The revascularized areas were divided into three different areas: S area, supplied by significantly stenosed coronary arteries (43 areas); C area, supplied by coronary collateral situation associated with totally occluded coronary arteries (12 areas); MI area, preexisting transmural myocardial infarction (7 areas). Myocardial contrast echocardiography was obtained by direct injection of 2 ml of sonicated 5% human albumin into the saphenous vein grafts at rest and during atrial pacing. Each area was divided into two layers of endocardial and epicardial halves, and myocardial enhancement of peak intensity was measured for each half and endocardial/epicardial gray level ratio was calculated: (1) The peak intensity of myocardial enhancement in S area and C area was significantly higher than that in MI area at rest as well as during pacing after myocardial revascularization. There was no significant difference in the peak intensity between S area and C area both at rest and during pacing. In S area the peak intensity significantly increased during pacing (p < 0.01), whereas it did not change in C area and MI area. (2) S area demonstrated no significant change in endocardial/epicardial intensity ratio during pacing. In contrast, the ratio in C area significantly decreased during pacing. (3) In S area with preoperative percent increase of segmental wall thickening lower than 25%, there was a significant correlation (r = 0.84, p < 0.001) between the peak intensity of myocardial enhancement and the postoperative changes of percent increase of segmental wall thickening in the revascularized areas. Thus, immediately after myocardial revascularization, intraoperative myocardial contrast echocardiography could provide a quantitative assessment of regional myocardial perfusion as well as blood flow distribution in the areas with myocardial infarction and with coronary collateral situation and in the areas supplied by stenosed coronary arteries.

Cardiac Pacing, Artificial↗
PubMed1992

Evaluation of right ventricular function by regional wall motion analysis in patients after correction of tetralogy of Fallot. Comparison of transventricular and nontransventricular repairs.

Right ventricular function was assessed by regional wall motion analysis and by global function in 62 patients after repair for tetralogy of Fallot. Its relation to surgical procedures, with special attention to right ventriculotomy, was investigated. Patients were classified as follows: group Ia (n = 17), transpulmonary-transatrial repair without right ventriculotomy; group Ib (n = 22), transpulmonary-transatrial repair with minimal right ventriculotomy and small transannular patch; and group II (n = 23), transventricular repair with or without transannular patch. For regional wall motion analysis, fractional area change was used for three anterior parts obtained from hemiaxis area analysis of the lateral right ventriculogram. Ejection fractions were used for global right ventricular function. Functional assessment was done both at rest and during isoproterenol infusion, which is a stress test to evaluate cardiac functional reserve. At rest, group Ia showed better right ventricular anterior wall motion as well as global ejection fraction than did group II. Group Ib showed a global ejection fraction comparable to group Ia, with better regional wall motion in the middle anterior part of the right ventricle despite the depressed upper and lower anterior parts of the right ventricle. Group II showed depressed wall motion of the middle anterior part and the resultant impaired global ejection fraction. During isoproterenol infusion, group Ia showed significant increase in fractional area change of all anterior parts and in global ejection fraction. Group Ib showed significant increases in fractional area change at the middle and lower parts and in global ejection fraction comparable with group Ia. Otherwise, group II showed no significant change in fractional area change, or in global ejection fraction, at the upper and middle parts. These results indicated that transpulmonary-transatrial repair for tetralogy of Fallot provided better postoperative global right ventricular function and its reserve, with less impaired regional wall motion, than did the transventricular repair.

Cardiac Catheterization↗
PubMed1992

Global left ventricular performance and regional systolic function after suture annuloplasty for chronic mitral regurgitation.

BACKGROUND: In surgery for chronic mitral regurgitation, the mitral subvalvular apparatus, including annulus, may play an important role in preserving left ventricular (LV) performance. The suture annuloplasty for mitral regurgitation allows annular contraction of the mitral valve. The potential effects of suture annuloplasty on the postoperative LV performance have not been fully defined. METHODS AND RESULTS: Global and regional LV function in 12 patients with suture annuloplasty were compared with 12 patients with conventional mitral valve replacement (MVR). Cineangiography and echocardiography were obtained before and 10.8 months after surgery. End-diastolic volume index and end-systolic volume index decreased significantly in both groups after surgery (p < 0.01). Ejection fraction remained unchanged in the suture annuloplasty group, whereas it decreased significantly in the MVR group after surgery (p < 0.01). There was a significant inverse relation between ejection fraction and end-systolic wall stress in the two groups after surgery (suture annuloplasty group, r = -0.69, p = 0.01; MVR group, r = -0.60, p = 0.04). The intercept on the y axis was significantly (p < 0.005) higher in the suture annuloplasty group than in the MVR group. In the suture annuloplasty group, cross-sectional area ejection fraction at the mitral valve level and at the papillary muscle level by LV two-dimensional echocardiography remained unchanged after surgery. In the MVR group, they decreased significantly after surgery (p < 0.01). There was a significant correlation between the cross-sectional area ejection fraction and the global ejection fraction at both levels after surgery. Therefore, the improvement of the regional wall motion can be attributed to the improvement of the global LV performance after suture annuloplasty. CONCLUSIONS: These data suggest that suture annuloplasty can provide more desirable postoperative LV systolic performance than conventional MVR by preserving both the contraction of the mitral annulus and the mitral valvular-ventricular interaction.

Echocardiography↗
PubMed1992

[A case report of tetralogy of Fallot associated with total occlusion of the right coronary artery and complicated with infective endocarditis].

A 31-year-old male with tetralogy of Fallot (TF) and total occlusion of the right coronary orifice complicated with infective endocarditis successfully underwent total repair of TF and coronary artery bypass graft (CABG). The patient had severely suffered from symptoms including breathlessness, palpitation (SVT) and chest pain. The coronary arteriography revealed occlusion of the right coronary orifice. The preoperative course was further complicated by endocarditis with vegetation of the aortic valve that did not respond to antibiotics. Concomitant surgical procedures consisting of TF repair, CABG to the right coronary artery with saphenous vein graft and vegetectomy of the aortic valve were carried out. The postoperative course was uneventful though he underwent cholecystectomy for symptomatic gall stones after TF repair. The patient is now in NYHA class II.

Adult↗