Biomedical subjects

Marcus A. Lima

Publications and source records attributed to Marcus A. Lima.

3 recordsLinked to original sources

PubMed1999

Thyroid Peroxidase Expression in Diseased Human Thyroid Glands.

Histoenzymologic studies of the human thyroid have been restricted to attempts to differentiate benign from malignant tumors and, to our knowledge, there is no systematic study on the distribution and behavior of enzymes for several types of lesions of the thyroid gland. The aim of the present study was to investigate thyroid peroxidase (IPO) expression in diseased thyroids, as well as to study the role of this enzyme as a parameter to define the biological behavior of thyroid lesions. A total of 1 17 neoplastic and nonneoplastic lesions of the thyroid were evaluated. The expression of TPO was determined by the analysis of at least 200 cells/specimen. A rate of 80% of positive cells was considered a threshold for TPO positivity. TPO expression was detected in all nonneoplastic lesions of thyroid as well as in 78.8% of the adenomas. We also observed positivity for TPO in 20% of malignant lesions. Therefore, these findings do not allow separation of benign and malignant lesions of the thyroid based in the expression of TPO.

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PubMed1998

Thyroid Peroxidase and Thyroglobulin Expression in Normal Human Thyroid Glands.

The objective of the present study was to investigate thyroid peroxidase (TPO) and thyroglobulin (Tg) expression in normal thyroid tissue. Thirty-eight normal thyroids from fetuses(1) children, adults, and elderly subjects were evaluated. TPO and Tg expression was determined by analyzing at least 200 cells/specimen. A value of 80% was considered to be the threshold for TPO positivity. In terms of age, TPO expression occurs in fetuses along with follicle differentiation and is absent in solid follicles. TPO staining was cytoplasmic, and was more intense in the apical membrane in tissue from fetuses, children, and young adults. A perinuclear rang was found in tissue from older adults and from the elderly subjects. There was concomitant TPO and Tg expression in all groups studied. Tg expression was observed in all normal thyroids from all age groups. Tg expression was extremely variable (10-100% of the cells) and fainter than TPO expression.

Journal Article↗

PubMed1998

CD26 (Dipeptidyl Aminopeptidase IV) Expression in Normal and Diseased Human Thyroid Glands.

The objective of the present study was to investigate CD26 (dipeptidyl aminopeptidase IV) expression in normal and diseased thyroids and its relation to differentiation and cell proliferation. CD 26 was also evaluated as a possible marker of malignancy in thyroid neoplasias. A total of 38 normal thyroids and 117 diseased thyroids (neoplastic and non-neoplastic) were evaluated. CD26 and thyroglobulin (Tg) expression was determined by analyzing at least 200 cells/specimen. A minimum of 500 cells/specimen were counted to calculate the MIB-1-positive cell rate expressed as a percentage of total nucleated epithelial cells. CD26 expression was absent in all thyroids from fetuses and children. Among the adults, 7.1 % had CD26 expression only in oncocytic metaplastic areas. In 3 of the 7 elderly subjects, CD26 expression was present in 0.2-90% of epithelial cells. CD26 expression was observed in all diseased thyroids. Since this enzyme is also expressed in benign conditions, it is not useful as a marker of malignancy. There was no relationship between CD26 and Tg expression. The MIB-1-positive cell rate was found to be low for all kinds of thyroid tissues, and when the cell proliferation rate was analyzed according to CD26 expression, a greater cell proliferation rate was found in CD26-positive differentiated (follicular and papillary) carcinomas than in CD26-negative carcinomas. These results demonstrate that expression of this enzyme is related to the proliferative activity of follicular cells.

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