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Biomedical subjects

M Imazu

Publications and source records attributed to M Imazu.

At least 19 recordsLinked to original sources
PubMed2006

Cervicothoracic malignant peripheral nerve sheath tumor in a 12-year-old girl with neurofibromatosis type 1.

We encountered a 12-year-old girl with neurofibromatosis type 1 (NF1) who developed a low-grade cervicothoracic malignant peripheral nerve sheath tumor (MPNST). Computed tomography of the neck showed an elastic firm tumor measuring 7 x 6 x 4 cm and arising from the upper mediastinum. She had no pain or neurological symptoms, but the tumor enlarged to ca. 8 x 8 x 4 cm over the following 7 months. Although we had diagnosed a neurofibroma by preoperative incisional biopsy, the resected tumor showed low-grade MPNST in the central portion of the tumor. In treating a tumor in a patient with NF1, we must recognize that partial biopsies do not necessarily establish a definitive diagnosis and that a growing tumor may indicate malignant transformation.

Child↗
PubMed2003

Histological investigations into the difference between cystic and fusiform types of congenital biliary dilatation.

We investigated the histological differences in the common bile duct wall of bile ducts with congenital biliary dilatation, examining 10 cystic types and 11 fusiform types. A flattened mucosa was found in the cystic type, and a tufted mucosa was occasionally found in the fusiform type. Glands in the choledochus wall were less common in the cystic type than in the fusiform type. Smooth muscle fibre was more abundant in the cystic type than in the fusiform type, and it was markedly developed in the distal choledochus in the cystic type. Based on these results we suggest that the developmental difference of smooth muscle fibres in the distal choledochus in the embryonic period may be closely related to the morphological difference between the cystic and fusiform types of congenital biliary dilatation.

Bile Ducts↗
PubMed2001

Optimal time for predicting myocardial viability after successful primary angioplasty in acute myocardial infarction: a study using myocardial contrast echocardiography.

This study sought to elucidate serial changes in microvascular integrity during papaverine-induced hyperemia in the risk area for myocardial infarction. In addition, we attempted to determine the optimal time for predicting myocardial viability. Seventy-two patients who underwent serial myocardial contrast echocardiography (MCE) before and shortly after (day 1), 1 day (day 2), and 3 weeks (day 21) after recanalization were studied. In 18 of 72 patients, MCE was performed at baseline and during hyperemia using selective intracoronary infusion of papaverine. Both the peak grayscale ratio (PGSR) within the risk area, and the no- and low-reflow ratio (LR ratio) were analyzed in each stage. Left ventricular regional wall motion (RWM) was determined 6 months after recanalization. The correlation coefficient between PGSR with papaverine on day 1 and that on day 2 was 0.54 (p = 0.02); it was 0.50 (p = 0.04) between day 1 and day 21, and 0.82 (p = 0.001) between day 2 and day 21. On day 1, the correlation coefficient between the LR ratio with papaverine and RWM was 0.60 (p = 0.02), which changed to 0.72 (p = 0.003) on day 2 and 0.54 (p = 0.04) on day 21, respectively. The best time to predict viable myocardium was established on day 2 by receiver operating characteristics curves. ST-segment re-elevation, elapsed time from onset to recanalization, and antecedent angina pectoris were independent factors for PGSR on day 2 using stepwise and multiple linear regression analysis. This study suggests that the optimal time to estimate microvascular integrity for predicting myocardial viability might be 1 day after recanalization, which is neither shortly after recanalization nor during the convalescent stage.

Aged↗
PubMed2001

Quinapril with high affinity to tissue angiotensin-converting enzyme reduces restenosis after percutaneous transcatheter coronary intervention.

Experimental studies have demonstrated that vascular injury resulted in an induction of vascular angiotensin-converting enzyme (ACE), and have suggested that inhibition of vascular ACE might be important in the prevention of restenosis. The present study aimed to determine the effect of quinapril, an ACE inhibitor with high affinity to tissue ACE, on restenosis following coronary intervention. The design of this study was a prospective, randomized, open, and non-placebo controlled trial. Patients with ischemic heart disease were enrolled after successful percutaneous transluminal coronary angioplasty or stent implantation at 7 participating institutions. Two hundred and fifty-three patients with 294 lesions were randomly assigned to the quinapril (10-20 mg per day) group or control group. Administration of quinapril was continued for 3-6 months of the follow-up. Quantitative coronary angiography was performed before and after angioplasty and at follow-up. Core laboratory measurements were performed independently and blinded. Follow-up angiography was performed in 108 patients with 124 lesions in the quinapril group and in 107 patients with 130 lesions in the control group. The baseline characteristics and findings of angioplasty showed no significant differences between the two groups. However, in the quinapril group, restenosis per patient and per lesion was significantly lower (34.3% vs. 47.7%, p < 0.05 and 30.6% vs. 43.8%, p < 0.05). Multivariable analysis revealed that administration of quinapril independently contributed to reducing the restenosis per patient and per lesion (odds ratio, 0.73; 95% confidence interval, 0.54-0.99 and odds ratio, 0.75; 95% confidence interval, 0.57-0.99). In conclusion, quinapril significantly reduces restenosis following coronary intervention.

Aged↗
PubMed2001

Factors of biliary carcinogenesis in choledochal cysts.

The long-term complications of choledochal cysts include malignant degeneration of the epithelial lining of the biliary tract. Possible factors leading to malignant degeneration were examined by measuring amylase levels in the biliary tract, intraoperative biliary manometry and a histopathological study. 27 patients, 1 to 13 years of age, with choledochal cysts, were studied over a 13-year period. Amylase levels in the bile of choledochal cysts and the gallbladder were measured. The pressure profile of the biliary tract was recorded as the probe was withdrawn from the sphincter of Oddi (SO) to the distal end of the common bile duct. Hyperplasia of the gallbladder mucosa and malignancy of the biliary tract were investigated. Patients with high levels of biliary amylase had higher pressure differences between the SO and the duodenum than those with low levels of biliary amylase. The incidence of mucosal hyperplasia of the gallbladder mucosa was significantly higher in the fusiform type than in the cystic type. Adenocarcinoma in a cystic choledochal dilatation was found in a 12-year-old girl with high amylase levels. The cause of regurgitation of pancreatic juice into the biliary system might be due to a high pressure difference between the SO and the duodenum in addition to the lack of sphincter function at the abnormal junction of the pancreaticobiliary ductal system. Early diagnosis and surgical treatment to prevent the regurgitation leading to hyperplasia and malignancy of the biliary tract are important for children with choledochal cysts.

Adolescent↗
PubMed2001

Calibration with currently available low-radiopacity catheters for scaling in digital quantitative coronary angiography.

RATIONALE AND OBJECTIVES: In quantitative coronary angiography, the absolute diameters of coronary artery lumina are obtained by using a catheter as a scaling device. METHODS: We examined the effect of x-ray opacity on the accuracy of calibration methods that use such catheters by varying the concentration of contrast medium in the catheters in phantom experiments with a digital cine imaging system. RESULTS: With contrast-filled, currently available catheters, the average increase in the measured calibration factor from the gold standard (as determined by using a measuring scale) was 1.0% and 0.4% in the 13-cm and 17-cm image-intensifier modes, respectively, compared with -9.9% and -12.4% for catheters without contrast medium. The corresponding figures for catheters of the previous generation that lacked contrast medium were 1.0% and 0.4%, respectively. The image contrast of previous-generation catheters filled with saline was closer to that of current-generation catheters filled with contrast medium than that of current-generation catheters filled with saline. CONCLUSIONS: When used for quantitative coronary angiography by digital angiography, currently available low-radiopacity catheters give more accurate data when filled with contrast medium.

Calibration↗
PubMed2001

Hyperinsulinemia as a risk factor for restenosis after coronary balloon angioplasty.

The present study evaluated whether hyperinsulinemia is a predictor of restenosis after coronary balloon angioplasty in 69 patients who underwent elective coronary balloon angioplasty; patients were excluded if they were known diabetics being treated with insulin. Quantitative coronary angiography was performed before and after angioplasty and at follow-up. Restenosis was defined as the presence of > or = 50% stenosis at follow-up. Plasma insulin responses before, 30, 60, and 120 min after 75 g glucose load (OGTT) were measured. Plasma insulin levels were higher in patients with restenosis than in patients without restenosis. Minimal lumen diameter at follow-up was smaller, and percent diameter stenosis at follow-up was higher and late loss was greater in the highest sum of insulin levels during OGTT (sigma insulin) quartile (0.95+/-0.15 vs 1.47+/-0.09 mm, p=0.005; 66.3+/-5.8 vs 40.5+/-3.3%, p=0.0003; 0.90+/-0.15 vs 0.49+/-0.08 mm, p=0.02). Even after adjustment for coronary risk factors and administration of angiotensin converting enzyme inhibitors, the association of hyperinsulinemia with restenosis leads to the conclusion that hyperinsulinemia is a strong risk factor for restenosis.

Aged↗
PubMed2001

Association of apolipoprotein E phenotype with hypertension in Japanese-Americans: data from the Hawaii-Los Angeles-Hiroshima Study.

We evaluated the association between the phenotypes or alleles of apolipoprotein E and hypertension in Japanese-Americans living in Hawaii or Los Angeles. The study consisted of 932 nondiabetic participants aged 40-79 years. Of these participants, 315 were hypertensive, while the remainder were normotensive. The prevalence of hypertension was higher in subjects with the e2 allele than in those without. Using a multivariable prediction model that included age, serum glucose, insulin, lipids, and body mass index, we found the epsilon2 allele to be associated with hypertension in men (odds ratio (OR), 1.53; 95% confidence interval (CI), 1.05-2.24) and for both sexes combined (OR, 1.35; 95% CI, 1.05-1.73). In a follow-up study, 37 of the 352 (11%) normotensive subjects had developed hypertension 4 years after the baseline examination. The frequencies of the apolipoprotein E phenotype E3/2 and the epsilon2 allele were higher in the subjects who became hypertensive than in those who remained normotensive. The E3/2 phenotype was associated with incidence of hypertension after adjustment for age, sex, baseline body mass index, and systolic blood pressure (OR, 1.75; 95% CI, 1.01-2.90). When serum lipids, glucose, and insulin were included in this analysis, the E3/2 phenotype tended to be associated with the incidence of hypertension. In conclusion, the epsilon2 allele of apolipoprotein E was associated with hypertension in Japanese-Americans. This association may be mediated via high levels of serum triglycerides that in turn are mediated in part by the epsilon2 allele. Nonlipid mechanisms may also be responsible for the effect of the epsilon2 allele on hypertension.

Aged↗
PubMed2001

Hyperinsulinemia for the development of hypertension: data from the Hawaii-Los Angeles-Hiroshima Study.

The present study was to assess the association of metabolic factors including hyperinsulinemia, with the development of hypertension in Japanese-Americans. One hundred forty normotensive (<140/90 mmHg) subjects aged 40 to 69 years old from the Hawaii-Los Angeles-Hiroshima study were followed for 15 years. Patients with cardiovascular disease were excluded. Body mass index (BMI), blood pressure (BP), serum total cholesterol (TC), triglycerides (TG), uric acid (UA), and glucose and insulin responses at baseline, 1 h, and 2 h after a glucose load were analyzed. Seventeen subjects became hypertensive (systolic BP > or = 160 mmHg, diastolic BP > or = 95 mmHg, or received drug treatment) during follow-up. Age- and sex-adjusted BMI, BP, serum UA, TG, insulin, and changes in fasting glucose during follow-up were higher in subjects who later became hypertensive than in those who did not. There was no difference in the change in BMI. Age- and sex-adjusted relative risks for the development of hypertension by quartiles of BMI, serum UA, TG, and the sum of insulin values (sigmainsulin) during a glucose load were highest in highest quartile of the distribution. When age, sex, systolic BP, BMI, serum UA, TC, TG, fasting glucose, sigmainsulin, and the change in BMI were used in a proportional hazard analysis, hyperinsulinemia, hyperuricemia, and systolic BP were found to be significant risk factors for hypertension. In conclusion, hyperinsulinemia, as well as obesity, hyperuricemia, and hypertriglyceridemia were associated with hypertension in Japanese-Americans. Hyperinsulinemia and hyperuricemia were independent predictors of the development of hypertension.

Blood Glucose↗
PubMed2001

[Angina pectoris].

Explore the source record for details and available documents.

Angina Pectoris↗
PubMed2000

Arteriovenous malformation of the penis in an infant.

Arteriovenous malformations (AVMs) are common benign lesions in infancy, although they are rare in the genitourinary region. The authors report on a 2-year-old boy with a penile AVM. At presentation, there was venous dilatation and tortuosity of the prepuce without ulceration, which had been recognized at 1 year of age. Left internal iliac arteriography showed early venous filling leading to the diagnosis of AVM. Surgical excision was performed at age 2. The postoperative course was uneventful. At the 6-month follow-up, there was no evidence of recurrence. This is the first report of a penile AVM that was successfully treated by surgical excision.

Arteriovenous Malformations↗
PubMed1999

Mathematical simulation of the Wenckebach phenomenon in Purkinje fibers.

We were able to simulate the Wenckebach phenomenon using a model of a one-dimensional cable, consisting of 20 serially connected Purkinje fiber cells represented by the model of McAllister, Noble, and Tsien. The internal resistance between the 10th and 11th cells was modified to five times the normal. To reconstruct the action potential, the derivative equation was solved using a fourth-order Runge-Kutta algorithm. When the first cell of the cable was stimulated, periodically, at an interval of 610 ms, a 9:8 Wenckebach pattern was elicited in the conduction between the tenth and 11th cells. Lower order 5:4, 4:3, 3:2 Wenckebach patterns were observed at pacing cycle length of 605, 600-595, and 590-575 ms, respectively. At a pacing cycle length of 570ms or less, 2:1 block was elicited. In another simulation, only when INa, was 0 could the Wenckebach phenomenon be elicited in a cable model. in which internal cell resistance and membrane capacitance were uniformly set, but in which the INa of the center two cells of the cable were alternated between 1 and 0. A localized increase in internal resistance, a relatively long time constant of deactivation of the delayed rectifier outward current, and a relatively rapid rate of pacing cycle length was necessary to evoke the Wenckebach phenomenon. The conductance of the delayed rectifier current at the end of an action potential increased progressively, except after a dropped beat when it was allowed to decrease. It was concluded that the change of conductance affected the cable property of the fiber and consequently evoked the Wenckebach phenomenon.

Action Potentials↗
PubMed1999

Association of beta3-adrenergic receptor gene polymorphism with insulin resistance in Japanese-American men.

The Trp64Arg variant of the beta3-adrenergic receptor (beta3-AR) gene is relatively common in Japanese people. We hypothesized that this variant may be associated with obesity and insulin resistance when combined with a westernized lifestyle. To test this hypothesis, we investigated the relationships between the beta3-AR gene variant and obesity and insulin resistance in Japanese-American men, who are known to have a higher prevalence of type 2 diabetes mellitus (DM). The subjects were 152 Japanese-American men living in Hawaii, 83 with normal glucose tolerance (NGT), 40 with impaired glucose tolerance (IGT), and 29 with DM. The frequency of the Trp64Arg allele of the beta3-AR gene was 0.18, almost identical to that of the mainland Japanese. The prevalence of the Trp64Arg allele was 30.1% in NGT, 35.0% in IGT, and 41.4% in DM subjects (nonsignificant). The Trp64Arg variant of the beta3-AR gene showed no significant relationship with obesity or insulin resistance in NGT subjects. However, fasting and 2-hour insulin levels and insulin resistance as determined by homeostasis model assessment (HOMA) were significantly higher in IGT subjects with the Trp64Arg variant. Although indices of obesity were the same in IGT subjects with and without the Trp64Arg variant, differences in the body mass index (BMI) and percent body fat between NGT and IGT subjects were greater for individuals with the Trp64Arg variant. Thus, there is an association between the Trp64Arg variant of the beta3-AR gene and insulin resistance in Japanese-Americans with IGT.

Adult↗
PubMed1999

Suppression of airway inflammation by theophylline in adult bronchial asthma.

BACKGROUND: Chronic continuous airway inflammation caused by eosinophils has been noted to play critical roles in the pathophysiology of bronchial asthma, in addition to reversible obstruction and hypersensitivity of the respiratory tract. Therefore, suppression of chronic airway inflammation has become more important in asthma treatment. Although theophylline has been a conventionally used bronchodilator, it has been recently reported to have concurrent anti-inflammatory effects. OBJECTIVE: Accordingly, we studied the effects of a slow-release theophylline preparation, Theolong, on airway inflammation. METHODS: Administration of Theolong 400 mg/day to 24 patients with mild or moderate asthma and measuring eosinophil cationic protein (ECP), a marker of airway inflammation, and eosinophils in sputum and peripheral blood at 4 and 8 weeks. RESULTS: As a result, sputum ECP, serum ECP and sputum eosinophil count (%) were significantly lowered after 4 and 8 weeks. CONCLUSION: Thus, in the theophylline-administered group, slow-release theophylline, Theolong, was effective in treating asthma, with anti-inflammatory effects on inflammatory cells besides its bronchodilator action.

Administration, Oral↗
PubMed1999

Cardiac disease late after chest radiotherapy for Hodgkin's disease: a case report.

This report presents a case of occult constrictive pericarditis and mitral valve insufficiency following chest radiotherapy. A 44-year-old man had received radiotherapy for the treatment of Hodgkin's disease 8 years ago. At age 40 years, effusive pericarditis occurred and he was treated with intrapericardial drainage. Biopsy revealed a fibrotic and thickened pericardium. He developed congestive heart failure 3 years later. The patient was found to have occult constrictive pericarditis and mitral valve insufficiency. He underwent mitral valve replacement, tricuspid annul plasty, and pericardiectomy. Although there is the benefit of cure for the Hodgkin's disease, the prognosis after treatment is affected by radiotherapy-induced heart disease. After radiotherapy of the chest and mediastinum, long-term cardiological follow-up is recommended in order to detecting patients with radiation-induced heart disease, such as the present case.

Adult↗