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Tadashi Nakanishi

Publications and source records attributed to Tadashi Nakanishi.

9 recordsLinked to original sources
PubMed2005

Expression of macrophage inflammatory protein 3alpha in human inflamed dental pulp tissue.

Severe pulpitis resulting from dental caries is characterized by marked inflammatory infiltrate such as lymphocytes. Little is known about the recruitment of these cells into the dental pulp lesions of carious teeth. Macrophage inflammatory protein-3alpha (MIP-3alpha), a CC chemokine attracts CC chemokine receptor 6 (CCR6)-expressing T cells. We examined the distribution of MIP-3alpha-positive and/or CCR6-positive cells in human inflamed and normal dental pulp by immunohistochemistry. MIP-3alpha was observed in all inflamed pulp sections, and was mostly distributed in macrophages that had accumulated in the area adjacent to carious lesions. Furthermore, CCR6 expression was also observed in the infiltrating lymphocytes. In contrast, MIP-3alpha and CCR6 were rarely detected in normal pulp. These findings suggest that MIP-3alpha plays a role in the advancement of pulpal inflammation via the recruitment of CCR6-expressing lymphocytes.

Adult↗
PubMed2005

Electron beam CT versus 16-MDCT on the variability of repeated coronary artery calcium measurements in a variable heart rate phantom.

OBJECTIVE: High reproducibility of coronary artery calcium (CAC) scoring is a key requirement for monitoring the progression of coronary atherosclerosis. The purposes of this study were to compare electron beam CT and 16-MDCT scanners in the variability of repeated CAC measurements and to assess the factors influencing this variability. MATERIALS AND METHODS: CAC models of different sizes attached to a cardiac phantom with a programmable variable heart rate were scanned three times, and interscan variability of the CAC measurement was calculated each time. For helical CT, different slice-thickness images of either retrospective ECG-gated or prospective ECG-triggering reconstruction were obtained. The detection of small amounts of calcium, variability of the Agatston score, and CAC measurement algorithms (Agatston, volume, and mass scores) were compared between CT scanners and protocols. RESULTS: All 1-mm-sized calcium models were detected on 0.625- and 1.25-mm helical CT, whereas some were missed on electron beam CT and 2.5-mm helical CT. Retrospective ECG-gated thin-slice helical CT showed the lowest variability. Reduction of variability by volume and mass scoring algorithms was less effective on 0.625- and 1.25-mm-thickness CT. CONCLUSION: Retrospective ECG-gated thin-slice helical CT has the potential to be a useful tool for monitoring coronary atherosclerosis.

Algorithms↗
PubMed2003

An immunohistological study of the localization of bacteria invading root pulpal walls of teeth with periapical lesions.

We immunohistologically examined the prevalence and localization of bacteria invading dentinal tubules of the roots of teeth with infected canals. Forty extracted teeth with apical lesions were selected and divided into two groups: a group of untreated teeth and a group of canal-enlarged teeth. The bacteria in the specimens were detected by Brown-Brenn stain and the labeled-streptavidin-biotin method with specific antisera for 16-bacteria. Seventy percent of the examined teeth showed bacteria invading the dentinal tubules of the roots. Fusobacterium nucleatum, Eubacterium alactolyticum, E. nodatum, Lactobacillus casei, and Peptostreptococcus micros were abundant. Even in the canal-enlarged group, invasion of bacteria was observed in 65% of teeth. This study revealed the actual condition of bacteria in infected root dentin and suggested that the canal-enlargement procedure could not completely remove all the bacteria in the infected dentinal tubules of the root.

Adult↗
PubMedDate not supplied

Technical innovation of cardiac multirow detector CT using multisector reconstruction.

Multisector reconstruction is a newly developed algorithm for multirow detector CT in cardiac study. Using volume data sets obtained by ECG-gated scanning, we can reconstruct cardiac images at any desired phase of the cardiac cycle retrospectively. In retro-processing multiplanar and three-dimensional images, thin-slice images with overlapping increment have a great advantage due to increasing z-axis resolution. In this article, we present principles of the algorithm, a phantom study, clinical applications and perspectives for the future.

Adult↗
PubMedDate not supplied

Coronary artery calcium scoring using multicardiac computed tomography.

OBJECTIVES: To test the hypothesis that multicardiac-phase computed tomography (CT) improves the quantification of coronary artery calcium. METHODS: Calcium-phosphate on a cardiac phantom and 108 calcified plaques from 50 patients were scanned, and multicardiac-phase images were obtained. Motion artifacts and calcium scores of the calcified plaques were compared between cardiac phases and CT scanners. RESULTS: In the phantom images, motion artifacts differed between cardiac phases; thus, the calcium scores were either higher or lower than the score from the static state. In the patient study, motion artifacts of calcifications on the various coronary branches varied with the cardiac cycle, which profoundly influenced the calcium scores. CONCLUSION: Multicardiac-phase CT has the potential to improve the quantification of coronary artery calcium by determining the cardiac phase where motion artifacts are the least on individual calcified plaques.

Aged↗
PubMedDate not supplied

Pitfalls in 16-detector row CT of the coronary arteries.

Recently developed 16-detector row computed tomography (CT) has been introduced as a reliable noninvasive imaging modality for evaluating the coronary arteries. In most cases, with appropriate premedication that includes beta-blockers and nitroglycerin, ideal data sets can be acquired from which to obtain excellent-quality coronary CT angiograms, most often with multiplanar reformation, thin-slab maximum intensity projection, and volume rendering. However, various artifacts associated with data creation and reformation, postprocessing methods, and image interpretation can hamper accurate diagnosis. These artifacts can be related to pulsation (nonassessable segments, pseudostenosis) as well as rhythm disorders, respiratory issues, partial volume averaging effect, high-attenuation entities, inappropriate scan pitch, contrast material enhancement, and patient body habitus. Some artifacts have already been resolved with technical advances, whereas others represent partially inherent limitations of coronary CT angiography. Familiarity with the pitfalls of coronary angiography with 16-detector row CT, coupled with the knowledge of both the normal anatomy and anatomic variants of the coronary arteries, can almost always help radiologists avoid interpretive errors in the diagnosis of coronary artery stenosis.

Adult↗