Scanning Electron Microscopy of the Human Thyroid Gland and its Disorders

The characteristic scanning electron microscopic features of the normal thyroid gland, benign thyroid lesions such as nodular (adenomatous) and colloid goitre, adenomas and thyroiditis, and malignant tumors such as papillary carcinoma, follicular carcinoma, anaplastic carcinoma and medullary carcinoma are described. One or more cilia are present in the center of the follicular surface of almost every epithelial cell in the normal thyroid gland as well as in most goitres. Their number is reduced in adenomas and differentiated carcinomas. Medullary carcinomas and anaplastic carcinomas usually lack cilia. Variation in distribution and appearance of microvilli seems to be related to functional differences in the normal thyroid and goitres. In neoplastic conditions the abundance of microvilli steadily decreases from ordinary papillary carcinomas to follicular variants of papillary carcinoma and to follicular carcinoma. Most of the cells in medullary carcinoma and anaplastic carcinoma have few or no microvilli. Benign and neoplastic Hürthle cells have a very characteristic appearance. Distinct, smooth-surfaced cells are interspersed among cells rich in microvilli. The literature is reviewed. Our own experience from examinations of 264 thyroid specimens is included

Chromosomal, epigenetic and microRNA-mediated inactivation of LRP1B, a modulator of the extracellular environment of thyroid cancer cells

The low-density lipoprotein receptor-related protein (LRP1B), encoding an endocytic LDL-family receptor, is among the 10 most significantly deleted genes across 3312 human cancer specimens. However, currently the apparently crucial role of this lipoprotein receptor in carcinogenesis is not clear. Here we show that LRP1B inactivation (by chromosomal, epigenetic and microRNA (miR)-mediated mechanisms) results in changes to the tumor environment that confer cancer cells an increased growth and invasive capacity. LRP1B displays frequent DNA copy number loss and CpG island methylation, resulting in mRNA underexpression. By using CpG island reporters methylated in vitro, we found that DNA methylation disrupts a functional binding site for the histone-acetyltransferase p300 located at intron 1. We identified and validated an miR targeting LRP1B (miR-548a-5p), which is overexpressed in cancer cell lines as a result of 8q22 DNA gains. Restoration of LRP1B impaired in vitro and in vivo tumor growth, inhibited cell invasion and led to a reduction of matrix metalloproteinase 2 in the extracellular medium. We emphasized the role of an endocytic receptor acting as a tumor suppressor by modulating the extracellular environment composition in a way that constrains the invasive behavior of the cancer cells

Alambique : didáctica de las ciencias experimentales

resumen literal de la revistaEn este artículo se presenta el currículo de química de los dos primeros cursos de la educación secundaria en Portugal (10õ y 11õ, que corresponden a estudiantes de 16 y 17 años), recientemente elaborado en el proceso de revisión curricular, cuya aplicación está prevista para el curso 2003-2004. Siendo la química uno de los componentes de la asignatura de física y química, obligatoria en los cursos generales de ciencias y tecnología, se ha optado por una orientación ciencias-tecnología y sociedad, desde una perspectiva de desarrollo de la cultura científica de los estudiantes. Se fundamentan los puntos de partida considerados y se presentan, de forma resumida, los temas a desarrollar.CataluñaES

RET/PTC rearrangement is prevalent in follicular Hurthle cell carcinomas

Aims: The molecular alterations underlying follicular Hurthle cell carcinomas (FHCCs) are largely unknown. In an attempt to clarify this issue, we analysed a series of Hurthle cell tumours for the presence of RET/PTC and PAX8/PPARG rearrangements and BRAF, HRAS and NRAS mutations. Methods and results: We investigated a series of 20 follicular Hurthle cell tumours [17 FHCCs and three follicular Hurthle cell adenomas (FHCAs)]. RET/PTC rearrangements were found in 33% of FHCAs and in 38% of FHCCs. All RET/PTC-positive FHCCs had a solid pattern of growth. PAX8/PPARG rearrangement was present in 27% of the FHCCs which displayed, in most cases, a follicular architecture. NRAS mutation was detected in one FHCC. An FHCC with a solid/microfollicular growth pattern scored positive for both RET/PTC and PAX8/PPARG rearrangement. Conclusions: Our study has shown a significant association between RET/PTC rearrangements and FHCCs with a solid growth pattern, thus raising the possibility of using tyrosine kinase inhibitors for the treatment of patients with FHCCs, which are often refractory to radioiodine treatment