Biomedical subjects

Tsukasa Ashihara

Publications and source records attributed to Tsukasa Ashihara.

4 recordsLinked to original sources

PubMed2003

Morphological abstraction of thyroid tumor cell nuclei using morphometry with factor analysis.

Various morphonuclear studies by digital image analysis have successfully been applied to quantify the nuclear morphology, including chromatin distribution pattern, in cytology of various organs; however, the majority of past reports have not shown correlation between the quantitative data by digital image analysis and cytological findings in practical diagnosis. In this report, we present the usefulness of morphological abstraction to combine the objective data and subjective observation in cytological diagnosis. Randomly selected, 100 cells in each Papanicolaou-stained ABC smear samples of 39 benign and malignant thyroid tumor cases were studied. Gray-level image data provided seven parameters for nuclear size, four parameters for nuclear shape, and 16 parameters showing the nuclear chromatin patterns from high-dimensional texture analysis of using co-occurrence and run-length matrices. To statistically abstract nuclear morphology, factor analysis was used. Factor analysis classified morphological nuclear characters as abstraction parameter into five abstract parameters composed of nuclear size, shape, heterogeneity, and contrast and homogeneity of chromatin pattern. The nuclei of papillary carcinoma showed larger size, more irregular shape, and higher contrast of chromatin pattern than those of the benign group. The follicular carcinomas have larger nucleus in each cell and more monotonous chromatin pattern among cells in each case than those of the benign group. Morphological abstraction by morphometry with factor analysis may provide a practical approach to the detection of the underlying characteristics of nuclear morphology in aspiration biopsy cytology.

Cell Nucleus↗

PubMed2002

Detection of underlying characteristics of nuclear chromatin patterns of thyroid tumor cells using texture and factor analyses.

BACKGROUND: Aspiration biopsy cytology of thyroid tumors has been used more frequently in recent times to differentiate between malignant and benign lesions. Chromatin patterns of the tumor cell nuclei are one of most important factors for cytologic diagnosis. The interpretation of nuclear chromatin patterns is subjective and more difficult than that of nuclear size or shape. In the present report, we investigated how to detect underlying chromatin characteristics of benign and malignant thyroid tumor cells by means of texture and factor analyses. METHODS: We employed a computer-aided system in which light microscopy was combined with an image processor and monochrome camera. Using this system, 100 randomly selected cells in a Papanicolaou stained, aspiration biopsy cytologic smear in each case of 39 benign and malignant thyroid tumor cases were digitized. We applied two-dimensional and higher texture analyses with the use of co-occurrence and run-length matrices to analyze the chromatin patterns. Factor analysis was used to determine whether a large number of independent variables actually measured one or more underlying common variables. RESULTS: According to parameters with high factor-loading values, the morphologic chromatin characters were classified into three categories according to heterogeneity, contrast, and homogeneity of chromatin patterns. On the basis of analyses with these morphologic categories, nuclei of papillary carcinoma showed higher contrast of chromatin patterns than did those of the benign group. Moreover, there was a variety of contrasting chromatin patterns among cells in each papillary carcinoma case in comparison with the benign group. In contrast, follicular carcinomas showed a significant difference in the standard deviation of factor 3, which indicated more monotonous chromatin patterns among cells in each follicular carcinoma case than in each benign case. CONCLUSION: We believe that this technique, using texture and factor analyses, is useful in the detection of underlying characteristics of nuclear chromatin patterns in aspiration biopsy cytology.

Adenocarcinoma, Follicular↗

PubMed2002

Simple tumor profile chart based on cell kinetic parameters and histologic grade is useful for estimating the natural growth rate of hepatocellular carcinoma.

Thirty-four untreated hepatocellular carcinomas (HCCs) with known growth rates were classified into 5 groups on a tumor profile chart based on their doubling time (DT), Ki-67-positive index (Ki-67-PI), apoptotic index (Apo-I), and histologic grade. The slow-growing HCCs (DT > 100 days) consisted of well-differentiated tumors with slight cell kinetic imbalance and were divided into groups A and B. Group A had Apo-I values <3%, and most tumors had Ki-67-PI values <10%, whereas group B had Apo-I values of 3 per thousand to 10 per thousand and Ki-67-PI values of 10% to 20%. The HCCs with intermediate growth rates, which had Ki-67-PI values similar to those of the tumors in group B, were divided into groups C and D based on differences in cell kinetics: group C consisted of well-differentiated tumors, most of which had Apo-I values <3 per thousand, and group D consisted of moderately or poorly differentiated tumors with Apo-I values between 10 per thousand and 20 per thousand. The rapidly growing tumors (DT < 50 days, group E) had higher Ki-67-PI values than other groups and a wide range of Apo-I values. Rapidly growing tumors were mostly moderately or poorly differentiated, with a large cell kinetic imbalance in favor of cell production. This grouping system is useful for approximating the growth rate of HCCs in a clinical setting, even when only histologic parameters are available.

Aged↗

PubMed2002

Acridine orange excited by low-dose radiation has a strong cytocidal effect on mouse osteosarcoma.

The study was conducted to clarify the cytocidal effect of combination therapy consisting of administration of acridine orange (AO), which is a photosensitizer, and radiation therapy using in vitro and in vivo mouse osteosarcoma models. The results revealed that AO combined with low-dose X-ray irradiation of about 1-5 Gy had a strong cytocidal effect on the cultured mouse osteosarcoma cells regardless of their chemosensitivity, and that this combination therapy inhibited growth of the in vivo mouse osteosarcoma by induction of tumor necrosis. This effect was inhibited by L-histidine, but not by mannitol. These findings suggested that AO might be excited by X-rays and kill osteosarcoma cells through the release of singlet oxygen, which is toxic to living cells. This mechanism is similar to that of photodynamic therapy with AO.

Acridine Orange↗