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Biomedical subjects

Y Hatanaka

Publications and source records attributed to Y Hatanaka.

At least 163 records · Page 9Linked to original sources
PubMed1977

A correlative study on the changes of cardiac dynamics and myocardial energy liberation in blood-let dogs.

Blood-letting of 450 to 1,000 ml with or without saline infusion was performed in dogs. In some dogs, right atrial pacing was carried out during blood-letting. Heart rate and isometric time-tension index were measured as the indicators of chronotropism and inotropism, respectively. After 60 min of blood-letting, dogs were sacrificed and mitochondria were isolated from the left ventricular myocardium. Mitochondrial respiration was measured polarographically and respiratory control index was calculated. As blood-letting advanced, the hearts revealed negative chronotropism with negative inotropism. Mitochondrial respiration was suppressed. When heart rate was forced to increase with atrial pacing, the hearts showed positive chronotropism with negative inotropism. Respiratory control index of mitochondria was deteriorated, showing uncoupling of oxidative phosphorylation. In consideration with our previous study on the ischemic heart, it is concluded that uncoupling of oxidative phosphorylation appeared in hypoxic myocardium when cardiac dynamics shifted to positive chronotropism with negative inotropism, though suppression of mitochondrial respiration was revealed when cardiac dynamics altered to negative chronotropism with negative inotropism.

Animals↗
PubMed1976

Hepato- and cardiotoxicity of xanthoascin, a new metabolite of A. candidus Link, to mice. I. Blood chemistry and histological changes in mice.

Aspergillus candidus Link, one of the commonest constituents of cereal mycoflora, produces two kinds of mycotoxins, terphenyllin and xanthoascin, which show different chemical and toxicological properties. The latter, xanthoascin, caused severe hepatic injury with jaundice and focal or confluent necrosis of hepatocytes, when given to mice in doses of 6 mg/kg b.w. or higher by a single subcutaneous injection. With higher doses above 15 mg/kg, myocardial degeneration and necrosis was induced after a week or two in addition to the hepatic injury. Vacuolation of the nuclei of the alveolar interstitial cells of the lung and myocardial interstitial cells was another characteristic lesion caused by this mycotoxin. Other organs including the testicles and thymus were widely involved. The unique nature of lesions in the liver and heart may necessitate further investigations in the field of mycotoxicology in relation to human diseases such as nutritional hepatitis and primary myocardial degeneration.

Administration, Oral↗
PubMedDate not supplied

Struma ovarii: MR appearances.

BACKGROUND: Analysis of unenhanced and contrast-enhanced magnetic resonance (MR) images of struma ovarii, a rare benign neoplasm of the ovary, is the aim of this study. METHODS: T2-weighted and Gd-DTPA-enhanced T1-weighted MR images of five histologically proven struma ovarii were evaluated retrospectively. RESULTS: In all patients, unenhanced and contrast-enhanced T1-weighted MR images showed complex cystic masses composed of multiple cysts and a solid component, indicating the presence of large and small thyroid follicles. In four patients, the cyst fluid was hypointense on T1-weighted images and hyperintense on T2-weighted images. In one patient, the fluid was hyperintense on T1-weighted images and hypointense on T2-weighted images due to hemorrhage. CONCLUSION: A complex mass composed of multiple cysts and a solid component, indicating the presence of large and small thyroid follicles, appeared to be a characteristic MR finding of struma ovarii.

Adult↗
PubMedDate not supplied

Micronucleus test with cyclophosphamide using mouse peripheral blood reticulocytes.

The usefulness of the micronucleus test using supravital staining of peripheral blood reticulocytes with acridine orange was evaluated in two laboratories after administering cyclophosphamide (CYP) as a model chemical by intraperitoneal injection (i.p.) to CD-1 mice. The frequencies of micronucleated peripheral reticulocytes (MNRETs) increased dose-dependently at each sampling time. There were no significant differences in the results obtained with this new method by the two laboratories. Although the induction of MNRETs was delayed by about 24 h compared to that of micronucleated polychromatic erythrocytes (MNPCEs) in the bone marrow, the frequencies of MNRETs and MNPCEs were almost identical at each optical sampling time, 24 h for MNPCEs and 48 h for MNRETs. Therefore, it is concluded that this method is a suitable alternative to that using femoral marrow cells.

Animals↗
PubMedDate not supplied

MR imaging of atypical polypoid adenomyoma.

The magnetic resonance (MR) appearances of three cases of atypical polypoid adenomyoma are reported. The signal intensity of the tumor was similar to that of adenomyosis on T2-weighted MR Imaging (MRI). On contrast-enhanced study, irregular enhancement was seen in hyperintense areas on T2-weighted images. Atypical polypoid adenomyoma can be characterized as a hypointense polypoid mass with hyperintense foci on T2-weighted MR images, resembling the appearance of adenomyosis.

Adenomyoma↗
PubMedDate not supplied

Invasive adenocarcinoma of the uterine cervix: MR imaging.

The detection of adenocarcinoma of the cervix is difficult in clinical examination, leading to poor prognoses. We evaluated MR appearances of 23 patients with adenocarcinoma of the cervix and appearances of 65 patients with cervical SCCs were also evaluated for comparison. Both T2-weighted spin echo, dynamic and postcontrast Gd-DTPA enhanced techniques were obtained at a 1.5 Tesla MR unit. The results of our study showed that adenocarcinoma of the cervix have MR imaging features which may permit distinction from SCCs which include: large tumors with preservation of endocervical epithelium, lesser contrast enhancement, and greater enhancement of the tumor periphery. Understaging may be more problematic with adenocarcinoma than SCC.

Adenocarcinoma↗
PubMedDate not supplied

Dynamic MRI of small renal cell carcinoma.

OBJECTIVE: To evaluate the appearance of contrast-enhanced dynamic MRI of small renal cell carcinoma (RCC) (< 3 cm diameter). MATERIALS AND METHODS: Twenty-seven patients with 28 small RCCs were studied by both conventional spin echo and contrast-enhanced dynamic MRI for tumor detection and characterization. All tumors were detected by contrast-enhanced CT and confirmed by operation. Dynamic MRI was performed using a breath-hold fast low angle shot technique after rapid injection of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA). Characterization of a renal mass was done by the visual analysis of tumor vascularity as well as quantitative assessment of the contrast noise ratio (CNR) and degree of enhancement. RESULTS: With conventional spin echo MR and dynamic MR, 18 and 26 of 28 small RCCs were detected, respectively. In the dynamic study the tumor/renal medulla contrast was marked at 90-120 s after administration of Gd-DTPA (CNR:15.1). The tumor/renal medulla contrast in the dynamic study was more marked than that of postcontrast T1-weighted imaging (CNR, -0.25); T2-weighted imaging (CNR, 3.1); and T1-weighted imaging (CNR, -0.76). CONCLUSION: Contrast-enhanced dynamic MRI is a useful technique for the diagnosis of small RCC especially in a patient with renal insufficiency or allergy to iodinated contrast material.

Adult↗
PubMedDate not supplied

An experimental study of the effect of glucose-insulin-potassium solution on energy metabolism of infarcted cardiac muscle.

The effect of GIK (glucose-insulin-potassium) infusion on the energy liberation of the infarcted heart muscle was studied experimentally in relation to epicardial electrocardiographic changes and cardiac dynamics. In the case of 30-min coronary ligation, the spread of the zone showing ST segment elevation was not depressed significantly, but the mean voltage values of ST elevations were suppressed in the peri-infarcted area, and the uncoupling of oxidative phosphorylation in the peri-infarcted area was also obscured by the GIK treatment. Cardiac dynamics did not change with GIK treatment. On the other hand, in the 60-min coronary ligation, the spread of the zone showing ST segment elevation was reduced significantly and the negative inotropism induced by coronary ligation was suppressed with GIK infusion. However, the uncoupling of oxidative phosphorylation in the infarcted area and in the peri-infarcted area did not show any significant improvement. Therefore, the disturbed energy metabolism of the peri-infarcted area of 30-min ligation might be improved by the effect of GIK infusion. These data suggested that the GIK infusion improved the energy liberation of the so-called twilight zone at 30 min after ligation, and then reduced the genuine infarcted zone after 60 min of ligation.

Animals↗
PubMedDate not supplied

Disturbance of myocardial energy liberation in experimental charcoal embolism of canine pulmonary artery.

Experimental charcoal embolism of the pulmonary artery was produced in dogs. Changes in hemodynamics, electrophysiology, and cardiac energy liberation were observed. The effects of histaminic and antihistaminic drugs on these changes were also studied. After two infusions of charcoal suspension, acute right ventricular overloading was recognized hemodynamically and electrophysiologically. Mitochondria isolated from both ventricles exhibited uncoupling of oxidative phosphorylation polarographically. These changes were enhanced with histamine injection and reduced with diphenhydramine injection. Histamine was seen to have some uncoupling effects on the heart mitochondria and a slight effect on cardiac dynamics. It is concluded that oxidative phosphorylation of the heart mitochondria was uncoupled in the acute stage of experimental pulmonary embolism, and that histamine might emphasize this change directly or indirectly or both, that is, directly affecting the myocardial cell metabolism, and indirectly aggravating myocardial hypoxia through pulmonary vasoconstrictive action.

Animals↗