Mutaciones de línea germinal del proto oncogen ret en pacientes chilenos con cáncer medular tiroideo hereditario y esporádico / Germline mutations of the ret proto oncogen in chilean patients with hereditary and sporadic medullary thyroid carcinoma

Background: Medullary thyroid carcinoma (MTC) may occur either as a sporadic or familial disease. Multiple endocrine neoplasia (MEN) type 2, inherited as an autosomal dominant disease, is characterized by MTC only (FMTC) or coexistence of MTC with other endocrine neoplasia (NEM 2A, 2B). Germline mutations of the RET proto-oncogene (cRet) are found in the inherited forms and in some apparently sporadic MTC cases. Aim: To study RET mutations in 8 families with MEN 2. Material and methods: RET mutations were screened in peripheral blood DNA from 18 patients and 87 high risk carriers belonging to 8 MEN 2 families and 52 sporadic MTC. Exons 10, 11, 13, 14, 15 and 16 of the c-Ret were amplified by polymerase chain reaction (PCR) and examined by direct sequencing of PCR products and/or restriction enzyme analysis. Results: Five MEN 2A and one FMTC families with a germline mutation at codon 634, one MEN 2A and one FMTC family carrying a mutation at codon 620 were identified. Mutations were found in 23 out of 87 high risk carriers. In addition, we detected a S891A (exon 15) germline mutation in a sporadic MTC patient and in one out of her three sons and V804M (exon 14) in another sporadic MTC case and in one out of his six relatives, indicating in both cases the presence of a sporadic misclassified familial disease. Conclusions: These results underscore the importance of routine application of c-Ret testing in all cases of MTC either familial or sporadic

Neoplasias endocrinas múltiples: un modelo clínico para aplicar técnicas de genética molecular / Multiple endocrine neoplasia: a clinical model for testing molecular genetic techniques

Multiple endocrine neoplasias (MEN) are syndromes inherited as autosomal dominant. The application of the techniques of molecular biology has made possible the identification of the genes causing MEN 1 and 2. The gene responsable for MEN 1 belongs to the family of tumor suppressor genes and encodes for a protein named MENIN whose function remains to be elucidated. The identification of mutant MEN 1 gene carriers who are at risk of developing this syndrome requires frequent biochemical screening for the development of endocrine tumors. MEN 2 is a consequence of mutations in the Ret proto- oncogene (c-Ret). This gene encodes for a tyrosine kinase receptor thought to play a role in the development of neural crest- derived tissue. Members of kindred with either MEN 2A or MEN 2B should be screened by direct DNA testing early in life for mutations in c-Ret. Those with the mutation should be advised to have thyroidectomy at five years of age in children with MEN 2A and earlier in children with MEN 2B . Some cases of sporadic MTC are actually MEN 2A or Familial MTC after c-Ret testing is done, therefore routine application of this test is recommended in all cases of apparent sporadic MTC

Liberación de neuropéptido tirosina (NPY) de los terminales nerviosos en vasos mamarios / Liberation of tyrosine neuropeptide (NPY) from mammary vessels nerve endings

En este estudio caracterizamos la liberación de NPY de biopsias de la arteria y vena mamaria. Se induce la liberación de los neurotransmisores por medio de despolarización eléctrica de los nervios simpáticos perivasculares. Con estímulo de 70 V, 0,5 msec, 40 Hz por 5 min, segmentos de la arteria mamaria liberan 17,7 ñ 6,7 fmol (n=4) de NPY, la vena libera 4,3 ñ 1,5 fmol (n=4), valores que corresponden a un 1-2 por ciento del NPY en la biopsia. El NPY liberado por estímulo eléctrico no es metabolizado en la sinapsis neuroefectora. La liberación del NPY al medio de superfusión tiene un curso temporal lento, la máxima liberación ocurre a los 10 min del estímulo. La liberación del NPY es dependiente de la duración del estímulo (coeficiente de correlación = 0,647, p<0,01); y de la frecuencia de estimulación (coeficiente de correlación = 0,611, p<0,05), indicando que la liberación es un proceso controlado por la frecuencia de la descarga y por la intensidad del estímulo simpático vasomotor. El proceso de liberación es dependiente del calcio, ya que en ausencia de calcio extremo, la liberación de NPY se reduce en 78 por ciento. El NPY actúa sobre receptores postsinápticos, donde produce un efecto facilitador significativo de la acción vasomotora de NA y ATP. En conclusión, NPY se libera al espacio sináptico por exocitosis, donde participa junto a NA y ATP en la regulación del tono vasomotor simpático

Tumores de hipófisis: presentación clínica y evaluación del tratamiento por cirugía transfenoidal / Pituitary tumors: clinical presentation and assesment of transphenoidal surgical treatment

The clinical manifestations and the surgical treatment results of 280 patients (179 female), undergoing a total of 319 operations at the Asenjo Institute of Neurosurgery were retrospectively analyzed. The surgical approach for the first operation was transphenoidal in 89.3 per cent of patients and transcraneal in the rest. Tumors were non secretory in 169 (60.4 per cent)patients, prolactinomas in 75 (27.8 per cent) and produced acromegalia in 29 (10.4 per cent) and Cushing syndrome in 7 (2.5 per cent) patients. There was extraselar extension in 42 per cent of women and 71 per cent of men. The surgical treatment of prolactinomas corrected endocrine alterations in 25 of 29 and visual alterations in 18 of 27 patients assessed. Surgical treatment of acromegalia improved endocrine alterations in 11 of 13 and visual alterations in 4 of 10 patients assessed. Treatment of non secretory tumors corrected visual alterations in 38 of 64 patients assessed. The principal complication of transphenoidal surgery was transient diabetes insipidus in 6.8 per cent of patients. Overall mortality was 2.3 per cent for transphenoidal surgery and 5.6 per cent for transcraneal surgery. It is concluded that transphenoidal surgery is effective for the management extraselar complications of pituitary tumors and endocrine management of selected cases

Edulcorantes y productos dietéticos / Sweeteners and dietetic products

Los edulcorantes son productos útiles empleados muy comúnmente en la alimentación de los pacientes diabéticos y en regímenes hipocalóricos. Se presenta un análisis crítico de los diferentes edulcorantes calóricos y no calóricos actualmente disponibles en el mercado nacional analizando el aporte energético así como las ventajas y desventajas de cada uno de ellos. Se describen las características químicas y metabólicas del aspartame, endulzante no calórico y se comentan las investigaciones que se realizaron para lograr la autorización de su uso por la Federal Drug Administration (FDA). Se hace énfasis en que el profesional de la salud, debe tener conocimientos sobre los edulcorantes y productos dietéticos, a objeto de instruir a los pacientes para la correcta selección de ellos