ABSTRACT
Resumen El sarcoma fibromixoide de bajo grado (LGFMS) es un tumor de tejidos blandos de origen mesenquimal. Los sarcomas son un grupo heterogéneo, que representa el 1% de todas las neoplasias. Los sarcomas primarios del sistema nervioso central (SNC) son raros y representan solo el 0,7% del total de sarcomas, con una incidencia estimada de 3 por cada 10 millones de personas por año. En este artículo, se describe el caso de una mujer de 59 años que presentó un sarcoma fibromixoide intracraneal de bajo grado, localizado en la región parietal derecha. Se discute el curso clínico, estudios de imágenes, características histopatológicas y tratamiento de este diagnóstico infrecuente y, por lo mismo, muy poco reportado. El diagnóstico definitivo se obtiene, ciertamente, mediante estudios histo-patológicos.
Summary Low-grade fibromyxoid sarcoma (LGFMS) is a soft tissue tumor of mesenchymal origin. Sarcomas are a heterogeneous group, representing 1% of all neoplasm diagnoses. Primary sarcomas of the central nervous system (CNS) are rare, and represent only 0.7% of all sarcomas, with an estimated incidence of 3 per 10 million people per year. The case of a 59-year-old woman who developed a low-grade intracranial fibromyxoid sarcoma in the right parietal region, is described. The clinical course, imaging studies, histopathological features, and treatment approach of this unusual diagnosis, are discussed. Low-grade intracranial fibromyxoid sarcoma is a rare and probably under- reported condition. The definitive diagnosis is usually made through histo-pathological studies.
ABSTRACT
Peroxisomes are thought to be formed by division of pre-existing peroxisomes after the import of newly synthesized proteins. However, it has been recently suggested that the endoplasmic reticulum (ER) provides an alternative de novo mechanism for peroxisome biogenesis in some cells. To test a possible role of the ER-Golgi transit in peroxisome biogenesis in mammalian cells, we evaluated the biogenesis of three peroxisomal membrane proteins (PMPs): ALDRP (adrenoleukodystrophy related protein), PMP70 and Pex3p in CHO cells. We constructed chimeric genes encoding these PMPs and green fluorescent protein (GFP), and transiently transfected them to wild type and mutant CHO cells, in which normal peroxisomes were replaced by peroxisomal membrane ghosts. The expressed proteins were targeted to peroxisomes and peroxisomal ghosts correctly in the presence or absence of Brefeldin A (BFA), a drug known to block the ER-Golgi transit. Furthermore, low temperature did not disturb the targeting of Pex3p-GFP to peroxisomes. We also constructed two chimeric proteins of PMPs containing an ER retention signal "DEKKMP": GFP-ALDRP-DEKKMP and myc- Pex3p-DEKKMP. These proteins were mostly targeted to peroxisomes. No colocalization with an ER maker was found. These results suggest that the classical ER-Golgi pathway does not play a major role in the biogenesis of mammalian PMPs.