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Biomedical subjects

N Takeichi

Publications and source records attributed to N Takeichi.

At least 37 records · Page 2Linked to original sources
PubMed1998

Relationship between flow dynamics in the left atrium and hemostatic abnormalities in patients with nonvalvular atrial fibrillation.

To investigate the relationship between left atrial (LA) flow dynamics and hemostatic markers in nonvalvular atrial fibrillation (AF), 45 patients with nonvalvular AF who had not received anticoagulants were evaluated by transesophageal echocardiography. We determined the LA appendage flow and the presence of LA spontaneous echo contrast (SEC) or thrombus. We measured plasma levels of thrombin-antithrombin III complex (TAT), fibrinopeptide A, D-dimer, beta-thromboglobulin, and platelet factor 4 in peripheral blood as hemostatic markers. The patients were divided into a low-velocity group (n = 19; sum of peak emptying and filling LA appendage flow velocities < 40 cm/s) and a high-velocity group (n = 26; > or = 40 cm/s). The maximum LA diameter was significantly greater and the LA expansion fraction was significantly smaller in the low-velocity group than in the high-velocity group. LA SEC or thrombus was observed in 11 patients (58%) in the low-velocity group, but not in any patients in the high-velocity group (p < 0.001). The plasma levels of TAT, fibrinopeptide A, D-dimer, beta-thromboglobulin, and platelet factor 4 were significantly higher in the low-velocity group than in the high-velocity group. The plasma levels of TAT, fibrinopeptide A, beta-thromboglobulin, and platelet factor 4 were significantly higher in 8 patients without LA SEC or thrombus in the low-velocity group than in 26 patients in the high-velocity group. Patients with nonvalvular AF accompanied by an enlarged and dysfunctioning LA and a decreased LA appendage flow velocity had increased intravascular coagulation-fibrinolysis activity and platelet activation. These abnormalities may be closely related to the thrombogenetic state in patients with nonvalvular AF.

Adult↗
PubMed1998

Long-term effects of the angiotensin-converting enzyme inhibitor enalapril on chronic heart failure. Examination by 123I-MIBG imaging.

To examine the long-term effects of the angiotensin-converting enzyme (ACE) inhibitor enalapril on chronic heart failure, 10 patients (7 men and 3 women, mean age: 62 +/- 11 years) with chronic stable heart failure, classified as New York Heart Association (NYHA) functional class 2-3 for more than 3 months, and a left ventricular ejection fraction less than 45% were treated with 2.5-5.0 mg of enalapril once a day for 3-15 months (mean 7 months). The causes of heart failure were old myocardial infarction (n = 7), hypertension (n = 2), and atrial fibrillation (n = 1). Radioiodinated metaiodobenzyl guanidine (123I-MIBG) imaging, radionuclide angiography, and treadmill exercise test were performed before and after the treatment. With enalapril treatment, (1) left ventricular ejection fraction (LVEF) increased significantly from 38.3 +/- 6.9% to 47.5 +/- 14.7%; (2) sub-maximal exercise time increased significantly from 205 +/- 112 to 272 +/- 120 seconds; (3) the heart to mediastinum (H/M) ratio of 123I-MIBG increased significantly (early image: 1.99 +/- 0.38 versus 2.20 +/- 0.50; delayed image: 1.86 +/- 0.44 versus 2.09 +/- 0.51); and (4) the washout rate of 123I-MIBG decreased slightly from 29.1 +/- 9.1% to 25.4 +/- 7.0%. The improvement rate of LVEF was significantly correlated with the improvement rates of the H/M ratio and washout rate after treatment with enalapril. Thus, the long-term effects of enalapril can be observed in the cardiac sympathetic nervous system, and 123I-MIBG imaging appears to be useful for evaluating the therapeutic effects of enalapril on the cardiac sympathetic nervous system in patients with chronic heart failure.

3-Iodobenzylguanidine↗
PubMed1998

Reversible and irreversible tumor progression of a weakly malignant rat mammary carcinoma cell line by in vitro exposure to epidermal growth factor.

We examined the effects of epidermal growth factor (EGF) on tumor progression of a weakly malignant rat mammary carcinoma cell line, ER-1. In vitro treatment with EGF enhanced tumorigenicity, metastatic capacity and in vitro invasive capacity of ER-1 cells. The increased malignancy of ER-1 cells was reversible, when the cells were pretreated with EGF for 24 h, whereas it was irreversible when pretreated with EGF for 1 month. EGF treatment elevated the intracellular peroxide level in ER-1 cells. When ER-1 cells were treated with EGF in the presence of N-acetylcysteine, a chemical antioxidant, the reversible or irreversible EGF-induced progression was inhibited. These results suggest that the reversible or irreversible tumor progression in ER-1 cells occur in accordance with the duration of exposure to EGF, and that reactive oxygen species may be involved in the progression.

Acetylcysteine↗
PubMed1998

[Evaluation of cardiac function by various cardiac imaging techniques in mitochondrial cardiomyopathy: a case report].

A 39-year-old man with cardiomyopathy due to point mutation of mitochondrial DNA(3243) was admitted to our hospital because of exertional dyspnea accompanied by hearing disturbance and diabetes mellitus. Echocardiography revealed asymmetric hypertrophy of the anterolateral and posterior walls and systolic dysfunction of the left ventricle (fractional shortening = 18%). Pulsed Doppler mitral inflow velocity wave showed a pseudonormalized pattern. Iodine-123 betamethyl-p-iodophenyl-pentadecanoic acid (123I-BMIPP) myocardial scintigraphy showed decreased accumulation in the anterolateral, posterior, and apical walls. Left ventriculography showed moderately decreased ejection fraction (43%), and left ventricular end-diastolic pressure was mildly elevated (18 mmHg). Angiography showed normal coronary arteries, but coronary flow reserve measured by administering intravenous adenosine triphosphate was impaired in the left anterior descending and left circumflex arteries compared to the right coronary artery. Intracellular accumulations of abnormal mitochondria were detected by histologic examination of the cardiac and skeletal muscles. Evaluation of cardiac function showed that the area of myocardial hypertrophy was nearly consistent with the region of decrease in 123I-BMIPP accumulation and coronary flow reserve.

Adult↗
PubMed1998

[Cardiac amyloidosis with atrioventricular valve thickening and left atrial dysfunction: a case report].

A 70-year-old man with cardiac amyloidosis was referred to our hospital because of exertional chest pain accompanied by ischemic changes on electrocardiography on April 2, 1997. Transthoracic echocardiography revealed a normal size and normally contracted left ventricle without hypertrophy and "granular sparkling" quality of the myocardium, thickening of the mitral and tricuspid valves, and enlargement of the left atrium with reduced booster pump function. Pulsed Doppler mitral inflow velocity wave showed a pseudonormalized pattern, and pulmonary venous flow velocity wave showed a non-compliant pattern. Transesophageal echocardiography revealed thickening and reduced movement of the interatrial septum and reduced flow velocity in the left atrial appendage, suggesting left atrial dysfunction. Adenosine triphosphate (ATP) stress thallium-201 myocardial scintigraphy showed reversible patchy defect mainly in the posterolateral wall. Left ventricular end-diastolic and pulmonary capillary wedge pressures were mildly elevated. Angiography showed normal coronary arteries, but coronary flow reserve measured by administering intravenous ATP in the left anterior descending artery was severely impaired. A rectal biopsy specimen was positive by Congo red staining. Thus, angina pectoris in this patient may be due to amyloid infiltration of the small intramural coronary arteries. Atrioventricular valve thickening and left atrial dysfunction are important clues to diagnose cardiac amyloidosis.

Adenosine Triphosphate↗
PubMed1997

Copper concentration in hyperintense hepatocellular carcinomas of Long-Evans cinnamon rats on T1-weighted images.

The Long-Evans Cinnamon (LEC) rat has abnormal intrahepatic copper accumulation and spontaneously develops hepatocellular carcinomas following hereditary hepatitis. The hepatocellular carcinomas are very similar to human well-differentiated hepatocellular carcinoma in histopathological features and on MR images. Copper is believed to be one of the causes of hyperintensity of hepatocellular carcinomas compared to surrounding non-cancerous tissues on T1-weighted MR image. Eight LEC rats were studied by MR imaging. We measured copper concentrations from the hepatocellular carcinomas and surrounding non-cancerous liver tissues. Signal intensity of hepatocellular carcinomas without cystic areas was iso- to slightly hyperintense relative to surrounding non-cancerous tissues on T1-weighted images. Histopathologically, most of the tumors resembled human highly or well-differentiated hepatocellular carcinomas. Copper concentrations of the hepatocellular carcinomas were lower than the surrounding non-cancerous liver tissues. Copper may not be the cause of increased signal intensity typically observed on T1-weighted images of hepatocellular carcinomas.

Animals↗
PubMed1997

Preliminary study of improved perception of words with the same sound but different intonation in tinnitus patients following electrical stimulation of the ear.

The present study aimed to explain how tinnitus relief following electrical promontory stimulation affects detection of changes in pitch frequency. To determine the effects of tinnitus relief on the auditory system. Japanese words with the same sound but different intonation were used to verify the effects of tinnitus relief on pitch detection in tinnitus patients Eight out of 11 patients experienced relief of tinnitus following treatment. The averaged number of the ratio in 8 patients with relief of tinnitus, 0.58, was significantly higher (p < 0.02) than that in 3 patients without relief, 0.15. In comparison with averaged hearing level, there was no significant difference in averaged hearing level between 8 patients with relief of tinnitus (52.4 dBSL; SD: 11.4) and 3 without relief of tinnitus (58.0 dBSL; SD: 14.7) (p > 0.68). No significant difference in age between patients with and without relief of tinnitus was observed.

Aged↗
PubMed1997

Improved word perception in tinnitus patients following electrical stimulation of the ear: a preliminary report.

The present study showed that there were close relationships between tinnitus relief and improved word perception by means of a grammatically correct but non-sense Japanese word perception test. Fourteen out of 20 patients reported tinnitus relief and improvement in hearing. Nine out of the 14 patients were thought to be significantly improved in word perception. Improved word perception was observed in 7 out of 10 patients whose ears tested were opposite to ears treated while in 2 out of 10 patients whose ears tested were the same as ears treated. Improved word perception was observed in 5 patients at one segment, 2 patients at two segments and 2 patients at three segments. Improved word perception was observed in one patient at the first segment, 5 patients at the second segment, 5 patients at the third segment and 5 patients at the fourth segment. There were no significant differences in hearing level nor age in patients with and without relief of tinnitus.

Electric Stimulation↗
PubMed1997

Improved word perception following electrical stimulation of the ear in hearing-impaired patients without tinnitus.

Improved word perception in hearing-impaired patients following electrical stimulation of ears was shown by means of a grammatically correct but non-sense Japanese 4-segment sentence perception test. Improved word perception was reported in 15 out of 20 patients without tinnitus following electrical stimulation of ears. In 11 out of 15 patients, the number of incorrect words significantly decreased, showing that electrical stimulation of ears improved word perception. Improved word perception was observed in 5 out of 8 patients whose tested ears were contralateral to treated ears while in 8 out of 12 patients whose tested ears were the same as treated ears. The present study suggests that electrical stimulation of ears improves word perception in hearing-impaired patients without tinnitus.

Aged↗
PubMed1997

Laparoscopic transhiatal esophagectomy for advanced thoracic esophageal cancer.

We performed transhiatal subtotal esophagectomy under laparoscopic guidance to reduce the invasiveness of subtotal esophagectomy while preserving dissectional accuracy. In six cases of advanced thoracic esophageal cancer with distant metastasis, we used a special type of handpiece of ultrasonic surgical aspirator (CUSA) for laparoscopic surgery to dissect the esophagus from surrounding tissues and to isolate vessels entering it while viewing with the video monitor. Hemostasis of isolated vessels was effected by clips or electrocoagulation. There was no massive bleeding from the mediastinum during the operation, nor was there postoperative bleeding or infection. All patients regained normal swallowing ability and were discharged. Transhiatal esophagectomy under laparoscopic guidance is considered a safe, less invasive operative treatment for patients who are suffering from advanced thoracic esophageal cancer.

Aged↗
PubMed1997

Tricuspid inflow and regurgitant flow dynamics after mitral valve replacement: differences relating to surgical repair of the tricuspid valve.

BACKGROUND AND AIMS OF THE STUDY: Changes in tricuspid inflow and regurgitant flow dynamics were evaluated in patients with functional tricuspid regurgitation (TR) who underwent mitral valve replacement (MVR) with and without tricuspid annuloplasty (TAP). METHODS: In a group of 30 patients, all with atrial fibrillation, 15 underwent TAP performed according to the modified De Vega technique; the remaining 15 did not undergo TAP. Patients were studied before and serially after surgery, using pulsed and color Doppler echocardiography. The mean follow up was 4.7 years in the TAP group and 5.1 years in the non-TAP group. RESULTS: In the TAP group, immediately after surgery, the area of the TR jet decreased markedly, and the deceleration time of the tricuspid inflow velocity wave was significantly prolonged compared with that before surgery. By contrast, in the non-TAP group, both the area of the TR jet and deceleration time of tricuspid inflow velocity were virtually unchanged. The area of the TR jet remained small for a long period in the TAP group, but in non-TAP patients was increased in four cases over seven years, with two patients developing right-sided heart failure. Recent data showed the area of the TR jet to be significantly smaller, with maximum tricuspid inflow velocity significantly increased, and deceleration time of the tricuspid inflow velocity wave significantly prolonged in the TAP group compared with the non-TAP group. CONCLUSIONS: In patients with functional tricuspid regurgitation undergoing MVR, concomitant TAP may cause mild tricuspid stenosis, but produces sustained preventive effects against TR. Careful follow up is needed in patients who have not undergone TAP, as TR is not markedly decreased and may even be exacerbated. Aggressive TAP is recommended in patients showing dilatation of the tricuspid annulus, even if TR is mild.

Adult↗
PubMed1996

Hepatocyte growth factor and c-met expression in Long-Evans Cinnamon rats with spontaneous hepatitis and hepatoma.

The Long-Evans Cinnamon (LEC) rat is characterized by the spontaneous onset of acute and chronic hepatitis, followed by occurrence of liver cancer, and is thus able to provide a unique experimental model for human genetical liver disease, Wilson's disease. Hepatocyte growth factor (HGF) is a potent hepatotrophic factor in liver regeneration, and its expression is up-regulated in response to liver injuries. We found that the plasma HGF level in LEC rats rose markedly during the fulminant hepatitis phase, fell during the phase of chronic/cholangiofibrosis, and fluctuated during the hepatoma phase. Immunohistological staining of the liver revealed that the number of HGF-positive cells increased remarkably during the fulminant hepatitis phase, and that many of these cells were localized at the portal triads. Fewer HGF-positive cells were observed during the phase of chronic hepatitis. The surface of the hepatocellular carcinoma (HCC) cells and the cytoplasm of the nonepithelial cells in cancerous liver tissues were HGF-positive. The HGF-messenger RNA (mRNA) level in the liver rose in the fulminant hepatitis phase, fell in the chronic hepatitis phase, and was intermediate or high during the hepatoma phase. The expression of c-met mRNA was strong in the tissues of LEC rats with fulminant hepatitis and, especially, in the cholangiofibrosis tissues. c-met mRNA was also detected in HCCs. These results suggest that the HGF-c-met system may play an important role in the regeneration of hepatocytes as well as in the development of HCC in paracrine or autocrine mechanisms.

Animals↗
PubMed1996

Experimental bilirubin pigmentation of rat dentine and its detection by a qualitative analytical method.

An animal model of bilirubinemia was used to determine whether bilirubin present in pigmented teeth can be extracted and qualitatively analysed. The bile ducts of 10 Long-Evans Agouti rats were ligated and bilirubin (14 mg/kg per day) was injected intraperitoneally for 4 days. When the animals were killed 2 weeks later, pigmented lower incisors were observed in three animals. These teeth were dried, powdered and bilirubin was extracted with chloroform/methanol/acetic acid, 30:10:0.5, v/v for 10 min under sonication. After centrifugation, the supernatant was collected and evaporated. The residue was dissolved in chloroform and its absorption spectrum measured before and after diazo reaction. This resulted in a shift of the absorption maximum from 450 to 540 nm and indicated the presence of bilirubin in pigmented teeth. No bilirubin was found in the lower incisors of untreated control rats. This technique may be useful in distinguishing bilirubin staning from other intrinsic discolorations of teeth.

Acetic Acid↗
PubMed1996

Quantitative analyses of correlations of signal intensity on T1-weighted images and T1 relaxation time with copper concentration in the rat liver.

RATIONALE AND OBJECTIVES: To evaluate the effects of intrahepatic copper on magnetic resonance (MR) images, we studied the signal intensity (SI) of T1-weighted images and the T1 relaxation time of Long-Evans Cinnamon (LEC) rats, which have abnormal copper metabolism, and compared them with those of Sprague-Dawley (SD) rats. METHODS: We imaged the livers of four LEC rats before they developed hepatitis and four SD rats. The SI ratio of the liver to a phantom of polyvinyl alcohol gel was measured on T1-weighted images, and the T1 relaxation time was obtained from calculated T1 images. Copper concentration was measured by atomic absorption spectrophotometry. RESULTS: The mean copper concentrations in the liver of LEC rats were approximately 20-fold and statistically higher than in SD rats. There was no significant difference in the SI ratio and the T1 relaxation time between the LEC and SD rats. CONCLUSION: Intrahepatic copper does not significantly influence either the SI of T1-weighted MR images or the T1 relaxation time of the rat liver.

Animals↗
PubMed1996

Inhibition of hereditary hepatitis and liver tumor development in Long-Evans cinnamon rats by the copper-chelating agent trientine dihydrochloride.

Trientine dihydrochloride (trientine) is an alternative medicinal copper chelating agent for patients with Wilson's disease of penicillamine intolerance. We examined the effects of trientine on the spontaneous development of hepatitis and hepatic tumors, by its short-term and long-term administration to Long-Evans cinnamon (LEC) rats with an accumulation of copper in the liver, as animal models of Wilson's disease. Male rats were given trientine in their drinking water at 1500 ppm for 18 weeks, from 6 weeks to 24 weeks of age in short-term experiment, and 1500 ppm for 27 weeks then 750 ppm for 52 weeks, from 8 to 87 weeks of age in the long-term experiment. Development of hepatitis was observed in the control LEC rats at 18 weeks of age. They had high levels of plasma transaminases (glutamic oxaloacetic transaminase [GOT], glutamic pyruvic transaminase [GPT]), and on pathological examination, hepatocyte destruction was observed. Histological findings revealed that short-term administration of trientine inhibited the development of hepatitis remarkably. The plasma GOT and GPT levels of treated animals were only slightly higher than those of normal LEA (Long-Evans with agouti coat color) rats, a sibling line of LEC rats. Copper levels in the liver were decreased by a maximum of 50 percent. In the long-term administration of trientine, the incidence of hepatic cell carcinoma (HCC) in the treated rats was 67 percent that of the untreated LEC rats, and the number of HCCs per rat in the treated group was 0.7 +/- 0.5, being significantly lower as compared with 4.7 +/- 3.5 in the untreated rats. Additionally, the development of cholangiofibrosis in LEC rats was completely prevented by long-term administration of the agent. The copper level in the liver of treated rats was reduced by 33 percent at 87 weeks of age. Development of HCC in LEC rats might be partly, but not totally, because of copper accumulation. No effects on the levels of copper, iron, or zinc in the liver of LEA rats was detected, and no adverse effects were detected in either LEC or LEA rats after both short- and long-term administration of trientine in drinking water.

Alanine Transaminase↗
PubMed1996

Hepatocellular carcinoma induction in LEC rats by a low dose of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline.

A food-borne heterocyclic amine, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), induces hepatocellular carcinomas (HCCs) in F344 male rats at an incidence of 95%, when fed in the diet at 400 ppm for 61 weeks. In this study, the effect of a low dose of MeIQx was examined in Long-Evans with cinnamon-like coat color (LEC) rats, which have a mutation in Atp7b and suffer from hereditary hepatitis and HCCs, with high levels of copper accumulation in the liver. Rats of the LEC and Long-Evans with agouti coat color (LEA) sibling lines were given a diet containing 40 ppm MeIQx from the age of 23 weeks to 63 weeks, for a total administration period of 40 weeks. In LEC rats, HCCs were observed in 8/8 animals administered MeIQx, and 2/8 rats receiving a normal diet. The number of HCCs per rat (mean +/- SD) was 2.8 +/- 2.0 and 0.3 +/- 0.5, respectively. In the LEA rats, however, no tumors were induced by administration of MeIQx. These results indicate that damaged liver associated with compensatory cell proliferation is much more susceptible to chemical hepatocarcinogens, including MeIQx, than the normal liver.

Alanine Transaminase↗