Hormone | EPFL Graph Search

Une hormone est une substance produite de façon naturelle par un organe du corps, qui est transportée par le sang et agit sur d’autres organes. C'est une substance chimique biologiquement active, synthétisée par une cellule glandulaire et sécrétée dans le milieu intérieur où elle circule, agissant à distance et par voie sanguine sur des récepteurs spécifiques d'une cellule cible. Elle transmet un message sous forme chimique et joue donc un rôle de messager dans l'organisme. Le terme « hormone » (du grec , mettre en mouvement) a été adopté par Ernest Starling en 1905 pour désigner les substances qui assurent la liaison entre les divers organes. Fonctionnement Une hormone est une molécule messagère produite par le système endocrinien (une glande endocrine ou un tissu endocrinien) en réponse à une stimulation et capable d'agir à très faible dose. Elle est ensuite diffusée dans l'ensemble de l'organisme. Les hormones animales sont sécrétées par des glandes spécialisées et dif

Hormonal regulation of Stat5 in the mammary gland - from signaling to morphogenesis

Sergio Klinke

The mammary gland development is regulated by steroid and peptide hormones and occurs mainly after birth, compared to the majority of the other organs in the body. The principal hormones responsible for the breast development are the estrogen, the progesterone, the growth hormone, the epidermal growth factor and the prolactin. The latter one is of specific interest since it is required for further development of the gland through pregnancy and lactation. During pregnancy and lactation, alveolar structures develop and differentiate into secretory cells. The signal transducer and activator of transcription 5 (Stat5) is known to be the main effector of prolactin signaling during pregnancy, inducing alveologenesis and differentiation of epithelial cells into secretory cells. I investigated if Stat5 has a role before pregnancy. Protein expression as well as mRNA expression analysis of glands from ovariectomized mice which were artificially stimulated with ovarian hormones (estrogen and progesterone) and control vehicle showed evidences that Stat5 expression can be stimulated by these two hormones. Contrary to the role established until now for stat5 in the mammary gland, I found by fluorescence visualization of Stat5-null epithelium as well as whole mount staining of the same glands that Stat5 is required even before pregnancy since null epithelium showed highly reduced growth already in 3 weeks-old virgin mice. This may indicate a new role for this protein in cell proliferation or survival in early stages of mouse mammary development. Furthermore, transplantation experiment of Stat5-null epithelium into wild-type recipient mice showed that pregnancy state was not able to rescue the normal phenotype. This may be due to complete loss of these cells which happened during the 5 weeks left for the transplanted epithelium to expand the cleared fat pad. This discovery opens a new debate on Stat5 role in the mammary gland development.

2008

Islet Encapsulation: New Developments for the Treatment of Type 1 Diabetes

Léo Bühler, Sandrine Gerber, Yi Wang, Qixing Zhang

Islet transplantation is a promising approach for the treatment of type 1 diabetes (T1D). Currently, clinical islet transplantation is limited by allo - and autoimmunity that may cause partial or complete loss of islet function within a short period of time, and long-term immunosuppression is required to prevent rejection. Encapsulation into semipermeable biomaterials provides a strategy that allows nutrients, oxygen and secreted hormones to diffuse through the membrane while blocking immune cells and the like out of the capsule, allowing long-term graft survival and avoiding long-term use of immunosuppression. In recent years, a variety of engineering strategies have been developed to improve the composition and properties of encapsulation materials and to explore the clinical practicality of islet cell transplantation from different sources. In particular, the encapsulation of porcine islet and the co-encapsulation of islet cells with other by-standing cells or active ingredients for promoting long-term functionality, attracted significant research efforts. Hydrogels have been widely used for cell encapsulation as well as other therapeutic applications including tissue engineering, cell carriers or drug delivery. Here, we review the current status of various hydrogel biomaterials, natural and synthetic, with particular focus on islet transplantation applications. Natural hydrophilic polymers include polysaccharides (starch, cellulose, alginic acid, hyaluronic acid, chitosan) and peptides (collagen, poly-L-lysine, poly-L-glutamic acid). Synthetic hydrophilic polymers include alcohol, acrylic acid and their derivatives [poly (acrylic acid), poly (methacrylic acid), poly(acrylamide)]. By understanding the advantages and disadvantages of materials from different sources and types, appropriate materials and encapsuling methods can be designed and selected as needed to improve the efficacy and duration of islet. Islet capsule transplantation is emerging as a promising future treatment for T1D.

2022

Islet Encapsulation: New Developments for the Treatment of Type 1 Diabetes

Léo Bühler, Sandrine Gerber, Yi Wang, Qixing Zhang

2022

Hormonal regulation of Stat5 in the mammary gland - from signaling to morphogenesis

Sergio Klinke

2008