Planos conjugados y sistema de iluminación de Köhler en microscopía óptica / Conjugate planes and Köhler illumination in optical microscopy

Un adecuado conocimiento y comprensión del concepto de planos conjugados es de capital importancia en la utilización del microscopio por cuanto que desde hace ya bastante tiempo el diseño de los microscopios se basa en la correcta situación de sus dos conjuntos de planos conjugados. En 1893 August Köhler publicó el trabajo «Un nuevo sistema de iluminación en microfotografía» donde dio a conocer los fundamentos básicos de una técnica de iluminación que actualmente lleva su nombre. El conocimiento y aplicación de los principios del sistema de iluminación de Köhler constituye el elemento de mayor importancia en el correcto manejo de un microscopio. Dichos principios no siempre son bien conocidos y comprendidos por los usuarios del microscopio constituyendo una fuente frecuente de errores en microscopía, particularmente en microfotografía. En este artículo revisamos los principios básicos del concepto de planos conjugados y del sistema de iluminación de Köhler (AU)

Adequate knowledge and understanding of the concept of conjugate planes is of paramount importance in the use of the microscope and for a long time microscope design was based on the correct location of the two sets of conjugate planes. In 1893 August Köhler published the article «A new illumination system in microphotography» in which he introduced the basics of an illumination technique that now bears his name. The knowledge and application of the principles of the Köhler illumination system is the most important element in the proper handling of a microscope. These principles are not always well known or understood by the users of microscopes, frequently leading to errors in microscopy, particularly in photomicrography. This article reviews the basic principles of the concept of conjugate planes and Köhler illumination system (AU)

Molecular study of signaling-pathway genes in experimental rat thyroid carcinoma.

INTRODUCTION: A study was conducted on histological patterns and biomolecular changes in Goitrogen-induced experimental rat thyroid tumors. The link between the histological types observed and N-ras, B-raf, and PI3KCA gene mutations widely reported in human thyroid cancers was explored. MATERIAL AND METHODS: An analysis was done on paraffin-embedded tumor tissue sections from Wistar rats receiving 1% potassium perchlorate (KClO(4)) added to the ad libitum drinking-water supply over an 18-month period. Three experimental subgroups were formed, each comprising 10 thyroids: subgroup I (control) consisted of thyroids from untreated controls; subgroups II and III (experimental) consisted of thyroids from KClO(4)-treated rats, displaying capsular, vascular, or both invasion but no metastasis (II), or distant metastasis (III). DNA was extracted from paraffin-embedded tissues. To test for the genetic mutations most widely reported in human thyroid cancers, exon 1 of the N-ras gene, exons 9 and 20 of the PI3KCA gene, and exon 15 of the B-raf gene were amplified and sequenced. RESULTS: All tumors were of the follicular type. None of the 20 experimental rat thyroids displayed the expected gene mutations reported in humans. However, 90% of them contained four new B-raf gene mutations and all were silent and did not cause an amino acid substitution in the protein chain. CONCLUSIONS: Biomolecular analysis suggested that N-ras, PI3KCA, and B-raf gene mutations may not be involved in thyroid tumor formation using the experimental procedure applied in this study. But the four mutations in B-raf, though without functional repercussions, may be a specific marker for this tumor type.

The cadherin-catenin complex in nasopharyngeal carcinoma.

Abnormal Wnt signaling and impaired cell-cell adhesion due to abnormal E-cadherin and ß-catenin function have been implicated in many cancers, but have not been fully explored in nasopharyngeal carcinoma. The aim of this study was to analyze ß-Catenin cellular location and E-cadherin expression levels in nasopharyngeal carcinoma. E-cadherin expression levels were also correlated with clinical data and underlying pathology. ß-Catenin and E-cadherin expression were examined in 18 nasopharyngeal carcinoma and 7 non-tumoral inflammatory pharynx tissues using immunohistochemical methods. Patient clinical data were collected, and histological evaluation was performed by hematoxylin/eosin staining. ß-catenin was detected in membrane and cytoplasm in all cases of nasopharyngeal carcinoma, regardless of histological type; in non-tumoral tissues, however, ß-catenin was observed only in the membrane. As for E-cadherin expression levels, strong staining was observed in most non-tumoral tissues, but staining was only moderate in nasopharyngeal carcinoma tissues. E-cadherin expression was associated with ß-catenin localization, study group, metastatic disease, and patient outcomes. Reduced levels of E-cadherin protein observed in nasopharyngeal carinoma may play an important role in invasion and metastasis. Cytoplasmic ß-catenin in nasopharyngeal carcinoma may impair cell-cell adhesion, promoting invasive behavior and a metastatic tumor phenotype.

Inmunohistochemical profile of solid cell nest of thyroid gland.

It is widely held that solid cell nests (SCN) of the thyroid are ultimobranchial body remnants. SCNs are composed of main cells and C cells. It has been suggested that main cells might be pluripotent cells contributing to the histogenesis of C cells and follicular cells, as well as to the formation of certain thyroid tumors. The present study sought to analyze the immunohistochemical profile of SCN and to investigate the potential stem cell role of SCN main cells. Tissue sections from ten cases of nodular hyperplasia (non-tumor goiter) with SCNs were retrieved from the files of the Hospital Infanta Luisa (Seville, Spain). Parathormone (PTH), calcitonin (CT), thyroglobulin (TG), thyroid transcription factor (TTF-1), galectin 3 (GAL3), cytokeratin 19 (CK 19), p63, bcl-2, OCT4, and SALL4 expression were evaluated by immunohistochemistry. Patient clinical data were collected, and tissue sections were stained with hematoxylin-eosin for histological examination. Most cells stained negative for PTH, CT, TG, and TTF-1. Some cells staining positive for TTF-1 and CT required discussion. However, bcl-2, p63, GAL3, and CK 19 protein expression was detected in main cells. OCT4 protein expression was detected in only two cases, and SALL4 expression in none. Positive staining for bcl-2 and p63, and negative staining for PTH, CT, and TG in SCN main cells are both consistent with the widely accepted minimalist definition of stem cells, thus supporting the hypothesis that they may play a stem cell role in the thyroid gland, although further research will be required into stem cell markers. Furthermore, p63 and GAL-3 staining provides a much more sensitive means of detecting SCNs than staining for carcinoembryonic antigen, calcitonin, or other markers; this may help to distinguish SCNs from their mimics.

Molecular findings of nasopharyngeal carcinoma in a European population.

OBJECTIVE: To explore biomolecular characteristics of a group of patients with nasopharyngeal carcinoma from European (Spanish) hospitals, addressing the pathogenesis of the tumor and the response to treatment. STUDY DESIGN: Cyclin D1 and p16 expression were evaluated immunohistochemically in 33 tissue samples of nasopharyngeal carcinoma. CCDN1 gene amplification and p16 gene deletion were studied by fluorescence in situ hybridization. Patient clinical data were examined, and tissues were evaluated histologically using hematoxylin-eosin staining. RESULTS: Cyclin D1 overexpression was found in 19 cases, and p16 expression was undetected in 30 cases. An association was observed between impaired p16 expression and cyclin D1 overexpression (p = 0.034). Eleven patients displayed p16 gene deletion and CCDN1 gene amplification. CONCLUSION: Cyclin D1 overexpression and CCDN1 amplification, loss of p16 expression and p16 deletion may be among the genetic alterations involved in the pathogenesis of nasopharyngeal carcinoma.

Immunohistochemical organization patterns of the follicular dendritic cells, myofibroblasts and macrophages in the human spleen--new considerations on the pathological diagnosis of splenectomy pieces.

There is reliable information about how changes in spleen histology are influenced by the relationship among B and T lymphocytes, macrophages, dendritic cells and myofibroblasts. Moreover, if it can be applied in the day-by-day pathology laboratory. This work intends to elucidate morpho-functional aspects of relationships of these cells in the different spleen compartments, how they are influenced by pathological conditions and how basic immunohistochemical techniques could optimize the histopathological diagnosis. We analyzed the usefulness of the monoclonal antibodies CD45RO, CD20, CD21, CD35, CD68, caldesmon, the smooth muscle alpha-actin type 1 (SMA-1) in 91 specimens. CD21(+) CD35(+) follicular dendritic cells were organized into three patterns in agreement with the immune condition of the lymphoid follicle. Smooth muscle alpha-actin type 1(+)and caldesmon(+)myofibroblasts draw two double rings: marginal-perifollicular and germinal-marginal. The latter is closely related to T-cells. CD68(+)red pulp macrophages had clear and linear configuration. The interruption of this CD68(+) linear pattern in splenic marginal zone lymphoma cases could be a criterion to differentiate it from reactive hyperplasia. CD45RO, CD20, CD21, CD68 and SMA-1 provide a basic and quality immunohistochemical battery for a better comprehension of the human spleen and could improve its histopathological diagnosis.

W43X SDHD mutation in sporadic head and neck paraganglioma.

OBJECTIVE: To analyze the presence of SDHD gene mutations in patients with sporadic head and neck paraganglioma. STUDY DESIGN: The presence of somatic and germline SDHD mutations was investigated in 10 patients by polymerase chain reaction and direct sequencing. RESULTS: Two patients displayed mutations: 259C>T (P87S) in 1 case and 129G>A (W43X) in the other. The first was considered a neutral polymorphism. The second was present in the germline of 1 of her sons, who had an apparently unrelated testicular seminoma and loss of heterozygosity (LOH) in the tumor cells. CONCLUSION: This is the first reported case of an SDHD mutation carrier showing LOH in a testicular seminoma.

Decreased expression of calcium receptor in parathyroid tissue in patients with hyperparathyroidism secondary to chronic renal failure.

The response of parathyroid cells to serum calcium is regulated by a calcium-sensing receptor protein (CaR). In patients with chronic renal failure, hypocalcemia contributes to the parathyroid hyperplasia and increased parathyroid hormone secretion characteristic of secondary hyperparathyroidism (sHPT). However, patients with uremia also display reduced sensitivity to extracellular calcium; this seems to be owing to an alteration of the receptor mechanism. This study examined calcium receptor expression in the parathyroid tissue of patients with sHPT, using immunohistochemical techniques and comparison with normal tissue and parathyroid glands of patients with primary hyperparathyroidism. In all the glands studied, immunostaining was more intense in chief cells than in oxyphilic, transitional, and clear cells. The parathyroid glands of patients with sHPT displayed significantly reduced expression of CaR with respect to morphologically normal ones; a very similar reduction is reported in adenomas. Furthermore, in glands displaying multinodular hyperplasia, expression was less marked in nodule-forming cells than in internodular areas. The decreased expression of calcium receptors in the parathyroid tissue of uremic patients was thought to be owing to the different cell populations present; these parathyroid glands contained predominantly transitional, oxyphilic, and clear cells, which normally express fewer receptors than chief cells, which are more abundant in normal glands.

Long-term prognosis of teenagers with breast cancer.

We report 4 new cases of breast carcinoma in teenage girls diagnosed by use of histochemical and immunohistochemical methods. These cases of breast carcinoma in women under 20 years of age were found in the files of our department in the last 24 years (1976-2000). The patients had operable breast carcinomas corresponding to various histologic types (1 invasive ductal carcinoma associated with fibroadenoma, 2 secretory carcinomas, and 1 invasive lobular-type carcinoma). Simple mastectomy with low axillary lymph node dissection was performed in 2 postpubertal patients. Only 1 patient received adjuvant chemotherapy (case 4). After follow-up ranging from 76 to 126 months, 3 patients are alive and disease-free and 1 has disseminated metastatic disease. The correlations with prognosis-related risk factors (stage, age, previous benign lesions, family history, histologic types, hormonal receptors, and pregnancy) were examined.