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Biomedical subjects

I Ogata

Publications and source records attributed to I Ogata.

81 records · Page 5Linked to original sources
PubMedDate not supplied

Decreased collagen accumulation by a prolyl hydroxylase inhibitor in pig serum-induced fibrotic rat liver.

Hepatic fibrosis was induced in rats by repeated i.p. injections of pig serum. The hepatic hydroxyproline content increased to 2.1 times the normal control level at 6 weeks and to 3.2 times at 10 weeks. When P-1894B, an inhibitor of prolyl hydroxylase, was administered, there was a dose-dependent inhibition of the increase to nearly normal control levels at 6 and 10 weeks. There was also by histology a dose-dependent reduction in the degree of hepatic fibrosis. Hepatocellular damage was minimal and its extent did not vary with the degree of fibrosis or the treatment. P-1894B dose dependently reduced the hydroxylation of peptidyl proline in the fibrotic liver. These data suggest that P-1894B inhibited hepatic fibrogenesis by direct action on collagen but not by protection against hepatocellular damage leading to collagen formation. A prolyl hydroxylase inhibitor may be a candidate for use in treatment of hepatic fibrosis.

Animals↗
PubMedDate not supplied

Three-dimensional high-resolution dynamic contrast-enhanced MR angiography of the pelvis and lower extremities with use of a phased array coil and subtraction: diagnostic accuracy.

In this study, our purpose was to compare the high-resolution contrast-material-enhanced three-dimensional subtraction MR angiography with conventional angiography for occlusive disease in the pelvic and lower extremity arteries. A three-dimensional fast-imaging with steady precession (FISP) sequence with a 256 x 512 matrix was obtained on 1.5T MR unit using a phased array coil. Twenty patients with arteriosclerotic obstructive disease underwent subtraction dynamic contrast-enhanced MR angiography. In 15 patients, three regions (pelvis, upper knee, and lower knee) were sequentially obtained after repeated injection of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). In the other five patients, one region was imaged (total of 50 examinations); a maximum-intensity projection (MIP) algorithm was used for subtracted images. All patients also underwent conventional angiography. Angiographic images were divided into several anatomical segments. Three blinded radiologists independently graded a total of 50 anatomic segments with stenotic or obstructive diseases and 90 segments without disease. Subtracted images allowed resolution of small branch vessels in all examinations, although misregistration was seen in eight examinations of five patients. All arteries larger than 1 mm in diameter were visualized on subtracted images. For detection of significant stenosis (>50%), MR angiography had 96% sensitivity and 83% specificity. The correlation coefficient of degree of agreement between MR angiography and conventional angiography was .92. Stenotic vessels tended to be overestimated. We conclude that high-resolution dynamic contrast-enhanced three-dimensional MR angiography is capable of depicting small vessel anatomy of the pelvis and lower extremities. Sequential MR angiography of different regions was feasible by repeated injection of Gd-DTPA and subtraction. This technique is highly sensitive in detecting lesions, but stenosis tended to be overestimated.

Aged↗
PubMedDate not supplied

Radiological presentations of Castleman's disease.

The radiographic appearances of three cases of Castleman's disease of hyaline vascular type are reported. CT demonstrated homogeneous masses with marked contrast enhancement. Calcification was seen in one, and associated lymphadenopathy was seen in two. All tumors were hypervascular with prominent tumor blush on angiography. Sonography showed the masses to be hypoechoic with hyperechoic spots. On MR imaging, all tumors had homogeneous architecture with hypointensity on T1-weighted images and hyperintensity on T2-weighted images. In tumors with above characteristics in areas where lymphoid tissue is normally found, Castleman's disease should be added to the list of differential diagnosis.

Aged↗
PubMedDate not supplied

Pitfalls in image reconstruction of helical CT angiography: an experimental study.

This study was undertaken to evaluate the effects of the object related factors: background tissue and the direction of vessels on the morphological reproducibility of helical CT angiography. Cylindrical tubes filled with a diluted contrast medium were prepared to obtain vascular phantoms. The scan was performed within various background tissues. For the evaluation of the direction of the vessels, two types of vascular phantoms were prepared. The phantoms were scanned by varying beam collimations and scan pitches. Reconstructed CT images were markedly affected by the background tissue. The reconstructed images were also affected by the direction of vessels.

Angiography↗
PubMedDate not supplied

Marked hypophosphatemia with decreased serum 1,25-dihydroxyvitamin D in a patient with hepatocellular carcinoma complicating liver cirrhosis.

A 61-year-old male with hepatocellular carcinoma (HCC) complicating liver cirrhosis presented hypophosphatemia progressing with HCC expansion and serum alpha-fetoprotein elevation. These changes were associated with an increased fractional excretion of phosphate and decreased theoretical phosphate threshold. There was increased nephrogenous cyclic adenosine monophosphate despite normal serum parathyroid hormone. Serum 1,25-dihydroxyvitamin D levels were markedly reduced with normal 25-hydroxyvitamin D levels. There were no symptoms of osteomalacia, however, a slightly increased osteoid seam was elicited on autopsy. The hypophosphatemia could be explained by presumed secretion from HCC of humoral factors which have a phosphaturic effect and also inhibit 25-hydroxyvitamin D-1 alpha-hydroxylase in renal tubular cells.

Biomarkers, Tumor↗
PubMedDate not supplied

Metastatic liver tumor from cystic ovarian carcinomas: CT and MRI appearance.

OBJECTIVE: The initial and follow-up CT and MRI images of ten patients with hepatic metastases from ovarian tumors were retrospectively analyzed to establish their features and sequential changes in appearance. MATERIALS AND METHODS: Ten patients with hepatic metastasis from ovarian tumors received initial and follow-up CT and MRI examinations. Six patients were followed up every two to three weeks before surgical tumor resection. Both CT and MR images were analyzed by two radiologists. RESULTS: A total of fourteen lesions were detected by CT and MRI in 10 patients. All 14 lesions were demonstrated as areas of marked hyperintensity on T2-weighted MRI. Eleven cyst-like tumors were demonstrated as round or oval low density lesions on CT and as areas of hypointensity on T1-weighted imaging. Three lesions were shown as solid masses with slightly low attenuation at the initial CT examination and slightly low or iso-intensity areas on T1-weighted imaging, and these lesions showed early peripheral globular enhancement and delayed enhancement on contrast-enhanced CT and MR imaging. Cystic formation was observed two to three weeks later after initial study in all the 3 solid lesions. Rapid subcapsular effusion, which showed obvious enhancement on delayed Gd-DTPA enhanced MR imaging, was observed in two patients. CONCLUSION: The hepatic metastatic tumor from cystic ovarian carcinoma may manifest as a well-defined cystic lesion or as a solid mass, and the solid mass shows delayed enhancement on contrast-enhanced CT and MR imaging. Furthermore, rapid cystic formation and rapid subcapsular extension is frequently seen.

Adult↗
PubMedDate not supplied

Magnetic resonance imaging in chronic liver disease evaluated in relation to hepatic fibrosis--clinical and experimental results.

In 21 patients with chronic liver disease, the ratio of liver to muscle signal intensity on T1-weighted images was negatively correlated with the progression of hepatic fibrosis defined according to findings by laparoscopy and liver biopsy, and differentiated six patients with early chronic hepatitis from eight with liver cirrhosis. On T2-weighted images, the number of low intensity nodules comparable in size to regenerating nodules surrounded by connective tissues showed a positive correlation with stage. When hepatic fibrosis with no necrosis or fat infiltration was induced in rats, T2 values were positively correlated with hepatic hydroxyproline content, though there was no such correlation for T1 values. These results suggest that MR imaging may be useful for determining the progression of hepatic fibrosis in chronic liver disease. T2 values may directly reflect hepatic fibrosis.

Adult↗
PubMedDate not supplied

Semiquantitative analysis of fatty liver using spectroscopic imaging by dephasing amplitude changing (SIDAC).

The potential utility of spectroscopic imaging by dephasing amplitude changing (SIDAC) was evaluated in fatty infiltration in rats induced by cholesterol and ethanol. There was an excellent correlation between the in vivo fat-to-water ratio obtained from SIDAC and that in liver specimens from in vitro measurement (r = 0.97). SIDAC is a promising method for semiquantitative analysis of fatty infiltration of the liver.

Animals↗