Biomedical subjects

R Okada

Publications and source records attributed to R Okada.

At least 37 records · Page 2Linked to original sources

PubMed1998

Suppressive effect of simvastatin on intramural small coronary arterial lesions in cholesterol-fed rabbits.

The aim of this study was to examine the suppressive effect of simvastatin on intramural coronary arterial lesions in cholesterol-fed rabbits. In one experiment, six groups of rabbits were fed laboratory chow alone or with added 0.1%, 0.2%, 0.3%, 0.5% or 1.0% cholesterol for 16 weeks. In another experiment, four groups of rabbits were fed a 0.5% cholesterol diet and treated with simvastatin at 1, 3, or 5 mg/kg/day or placebo. In each rabbit, the levels of serum total cholesterol (TC) were determined at 1-week intervals to calculate the integrated values. The lesion induction ratio was defined as the ratio of intramural coronary arteries 50-150 microm in diameter with arterial lipoidosis to the total number of arteries of the same diameter. In the two experiments, there were positive correlations between the lesion induction ratio and integrated TC (r=0.785, P<0.0001 and r=0.763, P<0.0001, respectively). The slopes of the regression lines for integrated TC obtained in the two experiments were similar, but the lesion induction ratio in the simvastatin-treated group was always lower, by about 14%, in comparison with that in the non-simvastatin-treated group. These findings suggest that simvastatin induces lesion reduction not only by reducing the levels of circulating cholesterol but also by directly suppressing the development of lipoidosis.

Animals↗

PubMed1998

Eosinophilic myocarditis associated with toxicodermia caused by phenobarbital.

We report on a 37-year-old man with congestive heart failure caused by eosinophilic myocarditis associated with toxicodermia. He developed many annular skin eruptions and peripheral eosinophilia due to reactions against phenobarbital. Right ventricular endomyocardial biopsy revealed extensive infiltration of eosinophils in the myocardium. A drug lymphocyte-stimulating test (DLST) for phenobarbital was positive. His symptoms, cardiomegaly, and cardiac function were improved by discontinuing phenobarbital followed by oral administration of prednisolone. We conclude that this eosinophilic myocarditis must have been induced by an allergic reaction to phenobarbital and that long-term eosinophilia contributed to the myocardial injury.

Adult↗

PubMed1998

Limitations of angiotensin-converting enzyme inhibitor in restenosis of a deep arterial injury model.

Cilazapril (CLZ) has been reported to reduce intimal hyperplasia in a rat carotid model of restenosis. The purpose of this study was to determine whether CLZ inhibits restenosis after deep arterial injury in lathyritic rats. The lathyritic rat was used as a model of deep arterial injury; in this model the internal elastic lamina is easily broken by balloon injury because of the fragility of the connective tissue. Deep arterial injury is defined as rupture of the internal elastic lamina with damage to both the intima and the media. The rats were divided into 4 groups (n = 40): mild injury (intimal damage with intact internal elastic lamina), mild injury +CLZ, deep injury, and deep injury +CLZ. In the CLZ-treated groups, the drug was administered orally (10 mg/day) from 7 days before balloon injury until the time of sacrifice 21 days after balloon injury. The intimal hyperplasia was determined histologically using a computerized morphometry program. At sacrifice, blood pressure was lower in the CLZ-treated groups than in the untreated (control) rats (p < 0.05). In the mild injury model, CLZ decreased intimal hyperplasia markedly. In contrast, CLZ failed to reduce intimal hyperplasia in the rats with deep injury. CLZ markedly decreased neointimal hyperplasia in mild injury. In contrast, CLZ failed to reduce intimal area in deep injury. The type of arterial injury seems to determine the effectiveness of CLZ.

Angioplasty, Balloon↗

PubMed1998

[Unclassified cardiomyopathies: subspecies and their transformation].

Some cases with hypertrophic cardiomyopathy (HCM) progress to dilated cardiomyopathy (DCM), therefore, we hypothesized that a transforming-type phase between HCM and DCM could exist. This study was made based on a retrospective analysis of 471 of 1,388 patients with cardiomyopathy who underwent diagnostic myocardial biopsy in several hospitals between 1977 to 1995, and who were not diagnosed with restrictive cardiomyopathy, arrhythmogenic right ventricular dysplasia, specific heart muscle diseases, or electrical disturbance type of heart muscle diseases. Based on echocardiographic measurements, the 471 patients were classified into eight subgroups according to the presence or absence of three parameters. A: left ventricular hypertrophy (septal or posterior wall thickness > 12 mm), B: left ventricular dilation (left ventricular end-diastolic dimension > 55 mm), C: systolic dysfunction (left ventricular ejection fraction < 50%), is signified by plus or minus ([ABC]). HCM, DCM and normal heart are defined as [+(-)-], [-(+2)] and [-(-)-], respectively. Unclassified cardiomyopathy (UCM) was indicated as cardiomyopathy not diagnosed as HCM or DCM. Therefore, unclassified cardiomyopathies are signified as either [+2-], [+(-)+], [+3], [-(+)-] or [-(-)+]. Patients in each subgroup of UCM were followed up for 6.4 +/- 6.0 years and their clinical courses compared with the histological findings. Of the 471 patients, 111 (24%) were classified as UCM, 240 as HCM, and 120 as DCM. Severe myocardial disarray was noted more frequently in UCM [17 of 111 cases (15%)] than in DCM [7 of 120 cases (6%)] (p < 0.05), and not significantly higher than in HCM [34 of 240 cases (14%)]. Patients with UCM whose conditions deteriorated had positive pathological findings (15 of 26 cases) more often than those without deterioration (8 of 29 cases; p < 0.05). UCM could be a transforming type of cardiomyopathy for some patients with HCM who progress to DCM. In addition, there may be a positive correlation between the histopathologic findings and the clinical course.

Cardiomyopathies↗

PubMed1998

Mitral valve aneurysm as a sequela of infective endocarditis: review of pathologic findings in Japanese cases.

Mitral valve aneurysm is defined as a localized protrusion of the valve with a different radius from that of the remaining portion of the valve. The medical records and pathological findings of seven patients with mitral valve aneurysm [aged 48-69 years (mean 64), 4 males] and the pathological findings of other 29 Japanese cases were reviewed. All seven patients were diagnosed pathologically as infective endocarditis, but two patients had no documentation of clinical symptoms suggestive of infective endocarditis (latent infective endocarditis). The underlying lesion of the heart was aortic valve disease and/or fibrosal degeneration of the mitral valve. Only 29 of 36 Japanese case reports stated a precise description of the valve pathology. Of these 29 cases, 23 were associated with infective endocarditis, two with rheumatic valvular disease with fusion and/or shrinkage of the chordae tendineae, three with mitral valve prolapse or myxomatous degeneration of the mitral valve, and one with aortitis syndrome. Neovascularization was described in eight cases. Neovascularization with thick wall should be considered as post-inflammatory vascularization. This review indicates that patients with latent infective endocarditis and mitral valve aneurysm should be considered as potential candidates for valve surgery.

Aged↗

PubMed1997

Modular structures in the mushroom body of the cockroach.

The mushroom body (MB) is a higher center of the insect brain and is critical to olfactory and other forms of associative memory. Here, we report that repetitive modular subunits, which we refer to as slabs, are present in the internal matrix of the alpha lobe, a major output neuropil of the MB in the cockroach. The methods employed were osmium-ethyl gallate, Bodian-reduced silver, and Golgi staining procedures. A total of 15 dark and 15 pale slabs, each consisting of specific subsets of intrinsic neurons (Kenyon cells), alternate throughout the length of the alpha lobe. One of the major classes of MB output neurons, which are postsynaptic to Kenyon cells, exhibited segmented dendritic arbors that interact with every other slabs, i.e. only either dark or pale slabs. As each output neuron interacts with each specific set of dark or pale slabs, the slab likely functions as a unit for transmitting MB output signals.

Animals↗

PubMed1997

Apoptosis as a possible cause of wall thinning in end-stage hypertrophic cardiomyopathy.

A 15-year-old boy with hypertrophic cardiomyopathy died of congestive heart failure with progressive left ventricular wall thinning with poor systolic function. Microscopic examination revealed patchy fibrosis in the ventricular myocardium with wall thinning, and immunohistochemical evaluation of apoptosis showed apoptotic cells and bodies in the destroyed myocytes along the border between the fibrotic area and myofibril.

Adolescent↗

PubMed1997

Late persistent expressions of ICAM-1 and VCAM-1 on myocardial tissue in children with lymphocytic myocarditis.

BACKGROUND: Both intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) have been implicated in cardiac allograft rejection. However, there is little information about the relationship between the expression of these adhesion molecules and myocarditis in children. METHODS AND RESULTS: Immunoreactivities of ICAM-1 and VCAM-1 were examined by enzyme immunoassay in 31 biopsy specimens obtained from 11 pediatric patients with biopsy-proven myocarditis or cardiomyopathy. Five of the 11 patients had clear evidence of acute myocarditis. The other 6 had ECG abnormalities identified by mass screening for heart disease, and subsequently had been histologically diagnosed as having non-specific cardiomyopathy. The period between onset of myocarditis or identification of ECG abnormality and immunohistochemical studies was 23 to 60 days and 8 months to 3 years, respectively. Expression of ICAM-1 and VCAM-1 was assessed by counting ICAM-1 and VCAM-1 positive vessels and dividing by the total number of vessels. ICAM-1 was significantly present on 81% (P < 0.01) of myocardial tissue samples in the 5 patients with healing-stage acute myocarditis, and on 45% (P < 0.05) in the remaining 6 patients with non-specific cardiomyopathy, compared with 24% in control specimens obtained from right ventricular muscle resected at surgery for tetralogy of Fallot. VCAM-1 was also present on 50% (P < 0.05) of the samples from the 5 patients with acute myocarditis, but was not present in those with non-specific cardiomyopathy. CONCLUSION: This persistent expression of ICAM-1 suggests that myocardial cell damage may persist immunologically for a long period in myocarditis. In addition, immunostaining for these adhesion molecules may be diagnostic value in clinically silent lymphocytic myocarditis and chronic cardiomyopathy.

Adolescent↗

PubMed1997

Adjunctive Therapy with an Antithrombotic Drug Can Prevent Reocclusion and Induce Residual Thrombus Reduction After Percutaneous Transcatheter Angioplasty of the Thrombotic Lesions.

Acute reocclusion after successful angioplasty is a severe complication. The preventive effects of heparin, the synthetic antithrombin, argtroban, and the defibrinogenating agent batroxobin on reocclusion after balloon angioplasty of thrombotic occlusions were evaluated in canine iliac arteries. After the 2-hour-old thrombus was evaluated by angiography and angioscopy, percutaneous transcatheter angioplasty (PTA) was performed on the thrombotic stenosis. We used one of the three agents, heparin (100 U/kg), the antithrombin argatroban (0.3 mg/kg), or the defibrinogenating agent batroxobin (0.3 U/kg). Then angioscopy and angiography were performed before, just after, and 2 hours after PTA. After PTA, angiography revealed a marked reduction in percent stenosis in all groups (from 88 +/- 8% to 24 +/- 4% in the heparin group, from 79 +/- 7% to 26 + 11% in the argatroban group and from 89 +/- 12% to 32 +/- 7% in the batroxobin group). At 2 hours after PTA, angiography demonstrated a greater reduction in percent stenosis with argatroban (from 26 +/- 11% to 9 +/- 3%) and batroxobin (from 32 +/- 7% to 10 +/- 8%), and maintenance of percent stenosis reduced by PTA with heparin (from 24 +/- 5% to 28 +/- 9%) when compared with the significant reversal of percent obstruction in the control side. Angioscopic visualization also demonstrated a similar trend. These results show that these antithrombotic drugs have a preventive effect on reocclusion after balloon angioplasty for thrombotic obstruction.

Journal Article↗

PubMed1997

High-dose dexamethasone therapy for a 14-month-old boy with refractory idiopathic thrombocytopenic purpura.

A 14-month-old boy with refractory idiopathic thrombocytopenic purpura (ITP), who was successfully treated with pulsed high-dose oral dexamethasone therapy is reported. The platelet count increased after six scheduled courses of treatment (10 mg/day x 4 days, six courses). Twenty-four months later, the platelet count remained over 10.0 x 10(4)/microL. No obvious side effects were observed during or after the therapy. This treatment could be taken into consideration not only for adults but also for young children with refractory ITP. It is effective, safe, easy to administer, patient comfort is taken into consideration, and hospitalization duration and costs are minimized.

Anti-Inflammatory Agents↗

PubMed1997

Idiopathic restrictive cardiomyopathy with diffuse perimyocytic fibrosis--a rare observation.

Idiopathic restrictive cardiomyopathy (RCM) is rare. Even today little is understood of its etiology or underlying mechanisms, and definitive diagnostic criteria are lacking. In this report, we describe a case of idiopathic RCM in a young Japanese woman who died while awaiting cardiac transplantation during the 5-year course of the disease. Rare pathologic findings of diffuse perimyocytic fibrosis were revealed at autopsy.

Adult↗

PubMed1997

[Variations in mesenchymal cell activity between rheumatic and non-rheumatic valve disease].

Deoxyribonucleic acid (DNA) synthesis of mesenchymal cells in the diseased valve tissue of patients with rheumatic and non-rheumatic valve diseases were compared. Surgically resected mitral valves from eight rheumatic and eight non-rheumatic patients in their 40s were examined immunohistochemically to estimate the activity of the various mesenchymal cells by cell cycle analysis, using monoclonal antibodies to cyclin E, A, B1, p53, and b cl-2 after routine tissue fixation, paraffin embedding and sectioning. Cyclin B1-positive fibrocytes and fibroblasts of the spongiosa and fibrosa were observed in all non-rheumatic cases, whereas some lymphocytes in the perivascular area were cyclin B1-, p53- and b cl-2-positive in rheumatic cases. The distinct qualitative difference in the mesenchymal cells of valve tissue between rheumatic and non-rheumatic etiologies suggests a different mode of valve pathology.

Adult↗

PubMed1997

[Concealed infective endocarditis].

The occurrence of concealed infection or "natural remission" in infective endocarditis was investigated microscopically in 35 consecutive patients (36 valves) with infective endocarditis (between April 1987 and May 1995). Four patients were considered as having concealed or silent infective endocarditis. Preoperative diagnosis of these patients was mitral valve prolapse, rheumatic aortic valve stenosis with insufficiency, aortic valve prolapse and hypertrophic cardiomyopathy, respectively. These patients did not present with any clinical signs of infective endocarditis such as cardiac murmur and ventricular dysfunction. Histological examination of the excised valves revealed valvular perforation, small round cell infiltration, neovascularization, remnants of vascular smooth muscle cells, and organizing vegetations. These findings are consistent with the histological findings of infective endocarditis. Latent infective endocarditis may be present without inflammatory manifestation.

Aortic Valve Insufficiency↗

PubMed1997

[Home infusion therapy for cancer patients at a near-terminal stage--analysis of cases who died at home].

To improve the quality of life in cancer patients at a near-terminal stage, we assisted patients to stay home using a system for home infusion therapy (HIT) established at Osaka Prefectural Habikino Hospital in 1994. From April in 1995 to April in 1996, 25 patients were treated at home using the HIT system for longer than 7 days. Thirteen out of 25 patients still stayed at home even at a terminal stage and died in their residences. There was no difference either in the mean age or in the HIT duration between 13 patients who died at home and the remaining 12 patients who were readmitted to their hospitals before death. However, 47% of the patients who died at home had been told their diagnoses by doctors and realized their own prognoses, while only 17% of the patients who died in the hospital knew their diagnoses and prognoses. Seventy-seven percent of the patients who died at home were given home oxygen therapy (HOT), against 33% of the patients who died in the hospital. Furthermore, the patients who died at home were given more intensive care than the patients who died in the hospital, because the former had a larger family than the latter. In conclusion, HIT at a near-terminal stage and death at home may be more readily accepted by patients who know their diagnoses and prognoses and have a large family.

Adult↗

PubMed1996

Characteristics of patients with right bundle branch block and ST-segment elevation in right precordial leads. Idiopathic Ventricular Fibrillation Investigators.

To elucidate the clinical characteristics of patients with right bundle branch block and ST elevation in the right precordial leads, a prospective follow-up study was made in 63 registered patients, including 17 with a history of ventricular fibrillation (VF) and 14 with a history of syncope. The prevalence of coved type ST elevation was significantly higher in patients who had had cardiac events, and during the initial 15-month follow-up, 2 patients in the VF group died suddenly.

Adult↗

PubMed1996

Emerin deficiency at the nuclear membrane in patients with Emery-Dreifuss muscular dystrophy.

Mutations in the STA gene at the Xq28 locus have been found in patients with X-linked Emery-Dreifuss muscular dystrophy (EDMD). This gene encodes a hitherto unknown protein named 'emerin'. To elucidate the subcellular localization of emerin, we raised two antisera against synthetic peptide fragments predicted from emerin cDNA. Using both antisera, we found positive nuclear membrane staining in skeletal, cardiac and smooth muscles in the normal controls and in patients with neuromuscular diseases other than EDMD. In contrast, a deficiency in immunofluorescent staining of skeletal and cardiac muscle from EDMD patients was observed. A 34 kD protein is immunoreactive with the antisera--the protein is equivalent to that predicted for emerin. Together, our findings suggest the specific deficiency of emerin in the nuclear membrane of muscle cells in patients with EDMD.

Adolescent↗

PubMed1996

Differentiation induction therapy with all-trans retinoic acid (ATRA) in a patient with secondary 11q23 leukemia.

PURPOSE: Frequently recurrent leukemia is encountered in childhood and is usually resistant to multidrug therapy. We evaluated the efficacy of differentiation induction therapy in a child with leukemia. PATIENT AND METHODS: We administered all-trans retinoic acid (ATRA) alone, and then a combination of low-dose 1-beta-D-arabinofuranosylcytosine (Ara-C), to a 7-year-old boy who had leukemia secondary to etoposide with chromosomal abnormality 11q23. RESULTS: The patient exhibited a good response to ATRA and had a complete remission after combination therapy of ATRA and low-dose Ara-C. CONCLUSION: Differentiation induction therapy with ATRA was effective in treating a patient with recurrence of leukemia without t(15;17) translocation, and which is resistant to conventional cytotoxic treatment.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1996

Granule-laden perivascular cells observed in rabbits with experimental cerebral atherosclerosis.

Granule-laden perivascular cells distributed around the fine vessels in brain of hypertensive rabbits fed a cholesterol diet were examined by electron microscopy. Perivenule granule-laden cells contained secondary lysosomes, residual bodies, Golgi vesicles, fusion vesicles, and vacuoles. In periarteriole granule-laden cells, secondary lysosomes and vacuoles were not prominent. Findings indicated that the granule-laden cell may be a histiocyte that appears during the vascular reaction to hypertension and hypercholesterolemia. This vascular reaction may occur more strongly in the veins than the arteries.

Animals↗