High-frequency microsatellite unstable (MSI-H) colon tumors develop as a consequence of mutations at repetitive sequences in target genes. TGFBR2 and ACVR2, encoding TGFb superfamily receptors, and the proapoptotic gene BAX are frequent targets for frameshift mutation. We analyzed the effect of these mutations on survival and histology in 2 separate cohorts. Forty-eight MSI-H Dukes B2 colon tumors from a cohort of 172 patients had mutations in TGFBR2, BAX and ACVR2 correlated with patient survival. Further, 54 population-based MSI-H colon cancers of all stages from a cohort of 503 patients had mutations correlated with tumor stage, grade and size. Of 44 amplifiable MSI-H Dukes B2 tumors, 70% harbored TGFBR2, 63% BAX and only 4.5% ACVR2 mutations. While mutation alone did not influence survival, concomitant mutation of TGFBR2 and BAX was associated with an improved prognosis in Dukes B2 patients (p 5 0.05). ACVR2 mutations were more frequent in the second, populationbased cohort (stage II: 32.5%, p < 0.05). While no target gene mutation correlated with stage in this cohort, poor histological grade and large tumor volume were associated with mutant ACVR2, but not TGFBR2 or BAX mutations, and likely accounts for the lower prevalence of ACVR2 mutations in the first, well-differentiated Dukes B2 cohort. Because target gene mutations did not correlate with stage, they likely occur early in the pathogenesis of MSI-H cancers. Mutations in TGFBR2 and BAX may improve survival in MSI-H Dukes B2 patients, and mutations of ACVR2 may augment histological changes consistent with poor tumor grade that is characteristic of MSI-H colon cancers, and increase tumor size. ' 2005 Wiley-Liss, Inc.

The objective of this study was to evaluate the influence of thyroxine (T4) and triiodothryonine (T3) on steroid production by bovine granulosa and thecal cells. Granulosa and thecal cells were obtained from small (1 to 5 mm) and large (> or = 8 mm) follicles of cattle, respectively, and cultured for 4 d. We conducted six experiments to evaluate the effect of 2 d of exposure to various doses of T3 or T4. In insulin- or insulin plus FSH-treated granulosa cells of experiment 1, 30 and 100 ng/ml of T4 had no effect on aromatase activity or progesterone production. In experiment 2, in the presence of insulin and FSH, 1 and 3 ng/ml of T3 weakly (<1.4-fold) increased aromatase activity of granulosa cells but had no effect on progesterone production. Low doses of T4 (3 to 30 ng/ml) tested in experiment 3 had no effect on aromatase activity but increased (to as much as 1.4-fold) progesterone production by granulosa cells. In experiment 4, T4 (30 ng/ml) increased (to 1.2-fold) progesterone production by granulosa cells only in the presence of FSH and had no effect on aromatase activity. In thecal cells of experiment 5, in the presence of insulin and LH, 30 and 100 mg/ml of T4 increased androstenedione production to 2.3- and 2.8-fold, respectively; only 100 ng/ml of T4 was effective at stimulating progesterone production by thecal cells. In experiment 6, 1 ng/ml of T3 increased thecal cell androstenedione production to 3.9-fold, whereas 3 ng/ml of T3 was without effect; progesterone production was not affected by T3. These results support the hypothesis that thyroid hormones may have direct stimulatory effects on ovarian function in cattle, acting at the level of granulosa and thecal cells.

Este artículo presenta algunas técnicas cualitativas empleadas en investigación de mercados que pueden ser aplicadas al estudio de bienes agropecuarios. El objetivo de este artículo es evidenciar la utilidad del uso de estudios de mercado de tipo cualitativo para el sector agropecuario con énfasis en las percepciones del consumidor de fruta en fresco. Específicamente, se utiliza un grupo focal para ilustrar los conceptos con un caso de la guayaba en fresco. Se concluye que los resultados de estos estudios son útiles para pensaren estrategias de mercadeo y en posibles cambios en los procesos productivos agrícolas. Se observa entre las limitaciones que los resultados arrojados por estas técnicas no pueden ser extrapolados y requieren estudios de seguimiento.

Este estudio analiza en qué medida, usando el aroma como fuente de información de artículos como bolsos o maletines, el involucramiento del consumidor y la calidad percibida explican el precio percibido. El método es un diseño experimental intragrupo completo donde los sujetos evalúan 3 estímulos olfativos: cuero, cuero sintético y tela. Los resultados muestran que al emplear el involucramiento y la percepción de calidad como 2 perspectivas independientes y simultáneas al momento de evaluar el producto, el involucramiento no es relevante. Por lo tanto, es la variable calidad y no el involucramiento la que determina el precio percibido.

Los índices de competitividad reflejan un pobre desempeño del departamento del Valle del Cauca, especialmente en lo referente al capital humano. Una política pública de bilingüismo permite acumular capital humano a través de la educación en inglés, acceder a nuevos mercados y mejor información, lo que hace posible el desarrollo de otros factores necesarios para la competitividad de una región. En este documento se hace un primer diagnóstico del bilingüismo en el Valle del Cauca, con miras a brindar argumentos para la creación de una eficaz política pública de bilingüismo. Los datos procesados provienen del Censo ampliado de 2005, y los resultados obtenidos a partir de él no son alentadores, pues muestran la necesidad de convertir el bilingüismo en un tema de prioridad en la agenda pública.