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Biomedical subjects

S Hamada

Publications and source records attributed to S Hamada.

625 records · Page 35Linked to original sources
PubMedDate not supplied

Optical coherence tomography images of retinitis pigmentosa.

The retinas of 3 patients with typical retinitis pigmentosa (RP) were evaluated by optical coherence tomography (OCT), fluorescein angiography (FA), and fundus photography (FP). OCT showed that retinal thickness was decreased in the areas of the retina affected by RP, and nearly normal in the unaffected macular area. Reflectivity was partially decreased in the affected retinal areas and pigment masses were hyper-reflective. Reflectivity of the macular area was nearly normal except in the fovea, where it was decreased because of edema. Cystic spaces of the fovea were evident in Patient 1.

Aged↗
PubMedDate not supplied

Can acute interstitial pneumonia be differentiated from bronchiolitis obliterans organizing pneumonia by high-resolution CT?

PURPOSE: In the early stages, clinical and chest radiographic findings of acute interstitial pneumonia (AIP) are often similar to those of bronchiolitis obliterans organizing pneumonia (BOOP). However, patients with AIP have a poor prognosis, while those with BOOP can achieve a complete recovery after corticosteroid therapy. The objective of this study was to identify differences in high-resolution CT (HRCT) findings between the two diseases. METHODS: The study included 27 patients with AIP and 14 with BOOP who were histologically diagnosed [open-lung biopsy (n=7), autopsy (n=17), transbronchial lung biopsy (n=17)]. The frequency and distribution of various HRCT findings for each disease were retrospectively evaluated. RESULTS: Traction bronchiectasis, interlobular septal thickening, and intralobular reticular opacities were significantly more prevalent in AIP (92.6%, 85.2%, and 59.3%, respectively) than in BOOP (42.9%, 35.7%, and 14.3%, respectively) (p<0.01). Parenchymal nodules and peripheral distribution were more prevalent in BOOP (28.6% and 57.1%, respectively) than in AIP (7.4% and 14.8%, respectively) (p<0.01). Areas with ground-glass attenuation, air-space consolidation, and architectural distortion were common in both AIP and BOOP. CONCLUSION: For a differential diagnosis of AIP and BOOP, special attention should be given to the following HRCT findings: traction bronchiectasis, interlobular septal thickening, intralobular reticular opacities, parenchymal nodules, pleural effusion, and peripheral zone predominance.

Acute Disease↗
PubMedDate not supplied

Endosonographic probe-guided endoscopic removal of colonic pedunculated leiomyoma.

We report a rare case of endoscopic removal of colonic pedunculated leiomyoma with an aid of endoscopic ultrasonography (EUS). A 46-year-old man was admitted to our hospital with complaints of lower abdominal pain and alternating constipation and diarrhea. Colonoscopy revealed a small pedunculated polyp in the transverse colon covered with almost normal mucosa. EUS showed a hypoechoic solid tumor with clear margins and smooth contour in the second to third layer. We considered this lesion as a submucosal tumor of the colon with no continuity to the muscularis propria. We performed endoscopic removal of this tumor successfully, and histological diagnosis was a leiomyoma. Endoscopic removal of colonic pedunculated leiomyoma is rare. Moreover, in our case, EUS showed typical findings of colonic leiomyoma and was useful to assess the location of the submucosal tumor. We describe herein our experience and discuss similar cases reported in the English literature.

Colonic Neoplasms↗
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Acute and subacute non-infectious lung diseases: usefulness of HRCT for evaluation of activity especially in follow-up.

PURPOSE: The purpose of this study was to survey the usefulness of high-resolution CT (HRCT) for the evaluation of activity in acute and subacute non-infectious diffuse infiltrative lung diseases before and after corticosteroid treatment. PATIENTS AND METHODS: Sequential HRCT images and chest radiographs obtained before and after treatment were retrospectively evaluated in 33 patients with acute or subacute noninfectious diffuse infiltrative lung diseases. All these patients were histologically confirmed to have pulmonary Inflammation and to have responded to treatment with corticosteroid. Radiographic and CT scores were correlated with the degree of dyspnea and the results of arterial blood gas analysis using Spearman's rank-correlation coefficient. RESULTS: On follow-up HRCT, the profusion score of areas with increased attenuation was significantly correlated with arterial oxygen tension (PaO2) (p=.003, r=-.53) and the alveolar-arterial oxygen tension difference (AaDO2) (p=.001, r=.57). No other correlation was found after treatment. Nodular and linear opacities were more commonly seen on follow-up chest radiographs and HRCT images than on initial ones. CONCLUSION: HRCT is useful for the evaluation of disease activity in acute and subacute noninfectious infiltrative lung diseases before and after treatment if paying special attention to the profusion of ground-glass attenuation. Even if pretreatment HRCT has not been performed, posttreatment HRCT should be examined.

Acute Disease↗
PubMedDate not supplied

Pitfalls in the interpretation of multidetector-row helical CT images at window width and level setting for lung parenchyma.

This article describes pitfalls in the interpretation of multidetector-row helical CT (MDCT) images at the window width and level settings for lung parenchyma. On MDCT, linear artifacts, which look like black and white linear densities and are called "hurricane artifacts," radiate out from objects that have very different densities from their neighbors. For the evaluation of fine parenchymal details, a low table speed/slice collimation should be used. In fact, axial (step and shoot) scanning may be more effective for the evaluation of fine details. Since artifacts from vessels highly enhanced by contrast medium cause data blackout in the surrounding areas at high table speed/slice collimation, pulmonary parenchyma in such situations should be evaluated with unenhanced CT. Although multidetector-row helical CT is a promising tool for the evaluation of lung parenchyma, it is important to identify its shortcomings due to artifacts when interpreting images at the window width and level settings for lung parenchyma and to apply the appropriate methods for eliminating such artifacts.

Artifacts↗
PubMedDate not supplied

Evaluation of image quality and spatial resolution of low-dose high-pitch multidetector-row helical high-resolution CT in 11 autopsy lungs and a wire phantom.

PURPOSE: The aim of this study was to evaluate whether low-dose high-pitch (6:1) multidetector-row helical high-resolution CT is appropriate for the evaluation of various pulmonary abnormalities, including faint opacities. METHODS: Eleven autopsy lungs were scanned with a multidetector-row CT scanner using 2.5 mm x 4 beam collimation, effective slice thickness 3 mm, 6:1 pitch, 0.8 second gantry rotation speed, 20 cm Display FOV, high spatial frequency (bone) algorithm, and various radiation doses (120 kVp; 160, 80, 40, 24, and 8 mAs). The image quality of each CT set was assessed as adequate or inadequate for diagnosis by two independent observers. In addition, a wire phantom was scanned with the same parameters in order to describe the MTF curves. RESULTS: There was excellent agreement between the observers for the evaluation of image quality (kappa statistic, 0.84). The ratio of images evaluated as inadequate for 8 mAs and 24 mAs was significantly higher than that for 160, 80, and 40 mAs (p<0.01: chi-square test). MTF curves of both 8 and 24 mAs were significantly inferior to those of 40, 80, and 160 mAs (p<0.0 1, Friedman test), while the MTF curve of 40 mAs was relatively inferior to that of 160 mAs (p<0.05, Friedman test). CONCLUSION: More than 40 mAs in combination with 120 kVp is preferable for the evaluation of details of lung parenchyma by high-pitch. multidetector-row helical high-resolution CT.

Autopsy↗
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Effects of phenytoin on dental caries and plaque in Streptococcus sobrinus-infected rats.

Effects of phenytoin (PHT) administration on dental caries in rats infected with Streptococcus sobrinus 6715 were investigated. Twenty-day-old specific pathogen-free Fischer male rats were infected with S. sobrinus 6715 and fed diet 2000 containing 56% sucrose with or without PHT for 52 days. Antibody responses against anti-S. sobrinus in serum and saliva failed to show a statistical difference between PHT-treated and nontreated rats. These results indicate that PHT treatment increased plaque deposition and dental caries in the rats infected with S. sobrinus 6715 and fed diet 2000 containing PHT (1-2 mg/g), as compared with those similarly infected and fed diet without PHT (P < 0.001).

Animals↗
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Tongue cancer: correlation of MR imaging and sonography with pathology.

Ten patients with tongue cancer underwent both MR imaging and sonography. In seven of these patients, pathologic findings from glossectomies were correlated with MR and sonographic results. MR images of resected specimens also were obtained in two patients, and relaxation time was calculated in one of these patients. MR images (5- to 7-mm thick slices) were obtained by using a 0.1-T resistive magnet with a 128 x 256 acquisition matrix. MR and sonography had almost the same sensitivity for detecting primary-site tongue cancer. However, in the three patients with extraorgan spread of tumor, MR was superior, showing three of three cases, compared with sonography, which showed extraorgan spread in only one of the three cases. Although MR failed in one patient to differentiate postradiation scar tissue from tumor, because of similar relaxation time of both, this imaging technique proved to be an important adjunct to the physical examination in the staging of tongue cancer.

Adult↗
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Computed tomography reveals atypical localization of benign mediastinal tumors.

Computed tomographic appearances of 147 surgically proven mediastinal tumors (113 benign and 34 malignant lesions) were evaluated paying special attention to their localization or extension. Ten of the 113 benign lesions (9%) showed atypical or unique localization or extension, and were divided into three groups. In the first group, two lymphangiomas and one bronchogenic cyst spread over both the precardiovascular and the retrocardiovascular compartments, mimicking a malignant lesion. In the second group, the single cases of thymic hypertrophy, thymic cyst, schwannoma, and pericardial cyst were located atypically in the retrocardiovascular compartment. In the last group, two esophageal leiomyomas and one esophageal duplication showed upward and downward longitudinal extension beyond the azygos arch and the aortic arch.

Adult↗
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Anterior transfer of the long toe flexors for the treatment of spastic equinovarus and equinus foot in cerebral palsy.

Anterior transfer of the long toe flexors combined with the Baker procedure, or heel cord lengthening was used to correct equinus foot deformity in 21 patients with cerebral palsy. In more than two-thirds of the cases, heel-to-ball gait became possible. There were no significant recurrences that required re-operation. There were no complications caused by loss of original function in the long toe flexors even in younger patients. Excellent and good results were seen in 57.1% of the patients according to the overall results.

Adolescent↗
PubMedDate not supplied

Transcriptional activation of the bcl-2 apoptosis suppressor gene by the paired box transcription factor PAX8.

The bcl-2 proto-oncogene suppresses apoptosis in a variety of cell types and is essential for normal renal development. PAX8 is a member of the paired box class of transcription factors and is developmentally regulated. bcl-2 and PAX8 are both expressed in the kidney during development and throughout life, demonstrating a nearly identical pattern of expression. We used transient transfection reporter assays and electrophoretic mobility shift assays to test PAX8 transcriptional regulation of bcl-2. PAX8 transcriptionally activates the bcl-2 promoter and binds to promoter sequences in vitro. These findings establish that PAX8 can transcriptionally regulate bcl-2 and suggest that suppression of apoptosis is an important event in the development and maintenance of renal tubular epithelial structures.

Apoptosis↗