250 resultados para RET


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Mode of access: Internet.

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Mode of access: Internet.

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Mode of access: Internet.

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Volumes for 1845- include reports of government officials, committees, and other documents, most of them with special title page and separate paging.

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In Yiddish.

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El an?lisis de libros de texto se ha convertido desde hace muchos a?os en un amplio campo de investigaci?n en el cual existen numerosos trabajos, algunos autores preocupados por analizar el contenido (Cabrera, 2011), otros por la ret?rica (Izquierdo, 2005), las ilustraciones (Perales, 2002), los errores presentes en ellos (Qu?lez, 2009). El presente trabajo se realiza en el marco del proyecto de investigaci?n Pr?cticas Experimentales y Textos de Ciencias1 con el prop?sito de dar respuesta a las preguntas ?Cu?les son las concepciones de los textos sobre las pr?cticas experimentales? y ?Qu? tipo de pr?cticas experimentales se consideran en los textos? Y cuyo objetivo central era el de caracterizar las concepciones de los textos sobre las pr?cticas experimentales y sus implicaciones en la ense?anza de las ciencias. En esta l?nea cobra sentido tambi?n la manera en la que los autores de dichos libros hacen uso de la historia y la experimentaci?n para el desarrollo del concepto. Para este trabajo se enfoca espec?ficamente en los LT m?s utilizados por los maestros en formaci?n de la licenciatura en educaci?n b?sica con ?nfasis en ciencias naturales y educaci?n ambiental de la Universidad del Valle en el ?rea de qu?mica. Para lograr dicho prop?sito se utiliz? una metodolog?a de tipo cualitativo ? descriptivo que consisti? en tres fases a saber: Fase 1. Identificaci?n de los libros de texto universitarios de ciencias m?s utilizados, Fase 2. Descripci?n de las tres unidades sem?nticas, Fase 3. Descripci?n del aspecto hist?rico y el uso de la experimentaci?n sobre la reacci?n qu?mica. Para fase 1 se formul? una encuesta para determinar los LT universitarios de qu?mica m?s consultados por los docentes en formaci?n inicial. En la fase 2 fueron analizados los LT de mayor preferencia seg?n la encuesta, teniendo en cuenta su superestructura y macroestructura de acuerdo con Van Dijk (1992), as? como, la inclusi?n de la historia y la experimentaci?n en el cap?tulo correspondiente a las reacciones qu?micas teniendo en cuenta el modelo de las tablas de eventos utilizado por Garc?a (2011). Arrojando como resultado que la inclusi?n de la historia en estos LT universitarios es de car?cter anecd?tico y que la experimentaci?n juega un papel comprobatorio de las teor?as, constatando que existen diversas formas de presentar el contenido conceptual de la reacci?n qu?mica, observando en la mayor?a de los casos fragmentaci?n de este. Bas?ndose principalmente en actividades pr?cticas, de l?piz y papel que no necesitan de materiales extras para su soluci?n, evaluaci?n de tipo tradicional, ?nfasis en resoluci?n de problemas algor?tmicos, sin profundizar en: el an?lisis, comparaci?n, formulaci?n y comprobaci?n de hip?tesis, y la presentaci?n de una sola visi?n de ciencia de car?cter aproblem?tica y descontextualizada, en ese sentido, una visi?n cientificista donde solo importan los productos de esta actividad. Este trabajo permite reconocer el an?lisis de los LT especialmente los universitarios como un campo de estudio muy importante para los docentes en formaci?n inicial debido: a la gran penetraci?n que estos tienen en el proceso ense?anza ? aprendizaje; la necesidad (para los futuros docentes) de realizar una reflexi?n cr?tica sobre la visi?n de ciencia que se est? aprendiendo y que es principalmente transmitida por los LT.

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Medullary thyroid carcinoma (MTC) originates in the thyroid parafollicular cells and represents 3-4% of the malignant neoplasms that affect this gland. Approximately 25% of these cases are hereditary due to activating mutations in the REarranged during Transfection (RET) proto-oncogene. The course of MTC is indolent, and survival rates depend on the tumor stage at diagnosis. The present article describes clinical evidence-based guidelines for the diagnosis, treatment, and follow-up of MTC. The aim of the consensus described herein, which was elaborated by Brazilian experts and sponsored by the Thyroid Department of the Brazilian Society of Endocrinology and Metabolism, was to discuss the diagnosis, treatment, and follow-up of individuals with MTC in accordance with the latest evidence reported in the literature. After clinical questions were elaborated, the available literature was initially surveyed for evidence in the MedLine-PubMed database, followed by the Embase and Scientific Electronic Library Online/Latin American and Caribbean Health Science Literature (SciELO/Lilacs) databases. The strength of evidence was assessed according to the Oxford classification of evidence levels, which is based on study design, and the best evidence available for each question was selected. Eleven questions corresponded to MTC diagnosis, 8 corresponded to its surgical treatment, and 13 corresponded to follow-up, for a total of 32 recommendations. The present article discusses the clinical and molecular diagnosis, initial surgical treatment, and postoperative management of MTC, as well as the therapeutic options for metastatic disease. MTC should be suspected in individuals who present with thyroid nodules and family histories of MTC, associations with pheochromocytoma and hyperparathyroidism, and/or typical phenotypic characteristics such as ganglioneuromatosis and Marfanoid habitus. Fine-needle nodule aspiration, serum calcitonin measurements, and anatomical-pathological examinations are useful for diagnostic confirmation. Surgery represents the only curative therapeutic strategy. The therapeutic options for metastatic disease remain limited and are restricted to disease control. Judicious postoperative assessments that focus on the identification of residual or recurrent disease are of paramount importance when defining the follow-up and later therapeutic management strategies.

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Background: Primary hyperparathyroidism occurs in only 10%-30% of patients with multiple endocrine neoplasia type 2A (MEN2A), rarely as the sole clinical manifestation, and is usually diagnosed after the third decade of life. Summary: A5-year-old girl was referred for prophylactic thyroidectomy as she carried the p.C634R RET mutation. She was clinically asymptomatic, with a normally palpable thyroid and with the cervical region free of lymphadenopathy or other nodules. Preoperative tests revealed hypercalcemia associated with elevation of parathyroid hormone (PTH) (calcium = 11.2mg/dL, calcium ion = 1.48mmol/L, phosphorus = 4.0 mg/dL, alkaline phosphatase = 625U/L, parathyroid hormone (PTH) PTH = 998 pg/mL). A thyroid ultrasound was normal and parathyroid scintigraphy with (99m)Tc-Sestamibi revealed an area of radioconcentration in the upper half of the left thyroid lobe suggesting hyperfunctioning parathyroid tissue. She underwent total thyroidectomy and parathyroidectomy and developed hypocalcemia. The anatomopathological examination showed no histopathological changes in the thyroid tissue and an adenoma of the parathyroid gland, confirming the diagnosis of hyperparathyroidism. Conclusions: Primary hyperparathyroidism can be a precocious manifestation of MEN2A. This case report highlights that asymptomatic hypercalcemia should be scrutinized in children related to patients with MEN2A who carry a mutation in the RET proto-oncogene, especially mutations in the codon 634, before the currently recommended age of 8 years.

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Pheochromocytomas are tumors of the adrenal medulla originating in the chromaffin cells derived from the neural crest. Ten % of these tumors are associated with the familial cancer syndromes multiple endocrine neoplasia type 2, von Hippel-Lindau disease (VHL), and rarely, neurofibromatosis type 1, in which germ-line mutations have been identified in RET, VHL, and NF1, respectively. In both the sporadic and familial forms of pheochromocytoma, allelic loss at 1p, 3p, 17p, and 22q has been reported, yet the molecular pathogenesis of these tumors is largely unknown. Allelic loss at chromosome 1p has also been reported in other endocrine tumors, such as medullary thyroid cancer and tumors of the parathyroid gland, as well as in tumors of neural crest origin including neuroblastoma and malignant melanoma, In this study, we performed fine structure mapping of deletions at chromosome 1p in familial and sporadic pheochromocytomas to identify discrete regions likely housing tumor suppressor genes involved in the development of these tumors. Ten microsatellite markers spanning a region of similar to 70 cM (Ipter to 1p34.3) were used to screen 20 pheochromocytomas from 19 unrelated patients for loss of heterozygosity (LOH). LOH was detected at five or more loci in 8 of 13 (61%)sporadic samples and at five or more loci in four of five (80%) tumor samples from patients with multiple endocrine neoplasia type 2. No LOH at 1p was detected in pheochromocytomas from two VHL patients, Analysis of the combined sporadic and familial tumor data suggested three possible regions of common somatic loss, designated as PCI (D1S243 to D1S244), PC2 (D1S228 to D1S507), and PC3 (D1S507 toward the centromere). We propose that chromosome Ip may be the site of at least three putative tumor suppressor loci involved in the tumorigenesis of pheochromocytomas. At least one of these loci, PC2 spanning an interval of <3.8 cM, is Likely to have a broader role in the development of endocrine malignancies.

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Previous findings point to the involvement of the dorsal raphe nucleus (DRN) and dorsal periaqueductal gray (dPAG) serotonergic receptors in the mediation of defensive responses that are associated with specific subtypes of anxiety disorders. These studies have mostly been conducted with rats tested in the elevated T-maze, an experimental model of anxiety that was developed to allow the measurement, in the same animal, of two behaviors mentioned: inhibitory avoidance and one-way escape. Such behavioral responses have been respectively related to generalized anxiety disorder (GAD) and panic disorder (PD). In order to assess the generality of these findings, in the current study we investigated the effects of the injection of 5-HT-related drugs into the DRN and dPAG of another rodent species, mouse, on the mouse defense test battery (MDTB), a test of a range of defensive behaviors to an unconditioned threat, a predator. Male CD-1 mice were tested in the MDTB after intra-DRN administration of the 5-HT(1A) receptor antagonist WAY-100635 or after intra-dPAG injection of two serotonergic agonists, the 5-HT1A receptor agonist 8-OH-DPAT and the 5-HT(2A/2C) receptor agonist DOI. Intra-DRN injection of WAY-100635 did not change behavioral responses of mice confronted with a rat in the MDTB. In the dPAG, both 8-OH-DPAT and DOI consistently impaired mouse escape behavior assessed in the MDTB. Intra-dPAG infusion of 8-OH-DPAT also decreased measures of mouse risk assessment in the rat exposure test. In conclusion, the current findings are in partial agreement with previous results obtained with rats tested in the elevated T-maze. Although there is a high level of similarity between the behavioral effects obtained in rats (elevated T-maze) and mice (MDTB and RET) with the infusion of 5-HT agonists into the dPAG, the same is not true regarding the effects of blockade of DRN 5-HT(1A) receptors in these rodent species. These data suggest that there may be differences between mice and rats regarding the involvement of the DRN in the mediation of defensive behaviors. (C) 2010 Elsevier B.V. and ECNP. All rights reserved.