A New Role for an Old Friend: NFAT and Stem Cell Quiescence

NFAT proteins are calcium-regulated transcription factors that play a critical role during the timing and activation of many vertebrate tissues. A recent paper in Cell (Horsley et al., 2008) demonstrates a role of the calcineurin-NFAT-CDK4 pathway in maintaining hair follicle stem cell quiescence

Hair cycle regulation of Hedgehog signal reception

AbstractProper patterning of self-renewing organs, like the hair follicle, requires exquisite regulation of growth signals. Sonic hedgehog (Shh) signaling in skin controls the growth and morphogenesis of hair follicle epithelium in part through regulating the Gli transcription factors. While ectopic induction of Shh target genes leads to hair follicle tumors, such as basal cell carcinomas, how Shh signaling normally functions during the cyclic process of hair development is unknown. Here, we show that, during the hair cycle, Shh expression and the ability of skin cells to respond to Shh signaling is spatially and temporally regulated. Induction of Shh target genes normally occurs only in the anagen hair follicle in response to expression of Shh. However, in patched1 heterozygous mice, putative tumor precursors form with concomitant induction of Shh target gene transcription only during anagen in follicular and interfollicular keratinocytes. Ectopic production of Gli1 accumulates Gli protein and induces Shh target genes and epithelial tumors at anagen but not other stages, pointing to a restricted competence occurring at the level of Gli protein accumulation. Delivery and reception of growth signals among multipotent cells are restricted in time and space to facilitate cyclic pattern formation

“Atypical” Regulation of Hedgehog-Dependent Cancers

Growing evidence indicates targeting PKCι may be effective in treating Hedgehog-dependent cancers. In this issue of Cancer Cell, Justilien and colleagues present the surprising finding that PKCι promotes Hedgehog ligand production and lung squamous cell carcinoma growth through SOX2, rather than the canonical transcription factor GLI

“Patch”ing Up Our Tumor Signaling Knowledge

The tumor suppressor Patched1 (Ptch1) possesses well-described roles in regulating sonic hedgehog (SHH) signaling in the skin and preventing the formation of basal cell carcinomas (BCCs). In this issue, Kang et al. extend their previous work to show that a naturally occurring allele of Ptch1 found in FVB mice promotes early squamous cell carcinoma (SCC) growth without aberrant activation of the SHH pathway. The study reveals new roles for Ptch1 that lie at the nexus between BCC and SCC formation

Simulación de procesos con controladores lógico-programables (PLC’s)

La realización de prácticas en el laboratorio de control de procesos presenta como mayor dificultad el coste asociado al funcionamiento del proceso, debido al consumo de reactivos, de energía o a la generación de residuos. Por tanto se propone trabajar con un proceso simulado en un controlador lógico- programable o PLC, con lo que se realiza una práctica de bajo coste y más cercana a la realidad que la pura simulación numérica

Diseno de una bomba centrifuga : analisis numerico y experimental

This paper describes the use of a rotating all mirror image derotator system in collaboration with Particle Image Velocimetry (PIV) to visualise and quantitatively examine the flow patterns between the blades of a centrifugal impeller. Velocity contours and vector maps of the relative flow field within a blade passage are presented for an impeller speed of 350 rpm and a flow rate of 510 l/h. The data are compared with the results of a computational fluid dynamics (CFD) model

Estudio numerico de las condiciones de estabilidad de estructuras bidimensionales bajo carga aerodinamica

An investigation on the stability conditions of the catenary wire system for a wide of wind relative direction is presented. The analysis was made with numerical methods by means of the Fluent software. The calculated lift forces were introduced in the equation of motion of the cylinders and stability conditions for the coupled system flow-structure were obtained