The preparation of a reconstructed human epidermis is described with examples of its utilization in in vitro studies. The model was obtained by culturing normal human keratinocytes at high cell density for 14 days in serum-free and high calcium (1.5 m M) medium on an inert polycarbonate filter at the air-liquid interface. These stratified cultures showed histological features similar to those observed in vivo in the epidermis: a proliferating basal layer and differentiating spinous, granular, and cornified layers. Electron microscopy illustrated lamellar bodies, junctions and keratohyalin granules. Immunofluorescent localization of epidermal markers (keratins 14 and 10, involucrin and filaggrin) revealed typical differentiation. This in vitro reconstructed tissue was used in studies of toxic effects of chemicals. The modelled tissue showed progressive cytotoxicity of a skin irritant (benzalkonium chloride) and a sensitizer (dinitrochlorobenzene) as assessed by MTT assay. Moreover, differential release of interleukin-1alpha and interleukin-8 were measured after 20 h of incubation allowing the irritant to be distinguished from the sensitizer. Permeation studies indicated efficient barrier function of the reconstructed epidermis, as well as metabolizing properties towards hormones. This model can be custom-made and is potentially useful for studies involving keratinocytes in the epidermis, in basic science, dermatology or toxicology.

NRAGE (also known as Maged1, Dlxin) is a member of the MAGE gene family that may play a role in the neuronal apoptosis that is regulated by the p75 neurotrophin receptor (p75NTR). To test this hypothesis in vivo, we generated NRAGE knockout mice and found that NRAGE deletion caused a defect in developmental apoptosis of sympathetic neurons of the superior cervical ganglia, similar to that observed in p75NTR knockout mice. Primary sympathetic neurons derived from NRAGE knockout mice were resistant to apoptosis induced by brain-derived neurotrophic factor (BDNF), a pro-apoptotic p75NTR ligand, and NRAGEdeficient sympathetic neurons show attenuated BDNF-dependent JNK activation. Hair follicle catagen is an apoptosis-like process that is dependent on p75NTR signaling; we show that NRAGE and p75NTR show regulated co-expression in the hair follicle and that identical defects in hair follicle catagen are present in NRAGE and p75NTR knockout mice. Interestingly, NRAGE knockout mice have severe defects in motoneuron apoptosis that are not observed in p75NTR knockout animals, raising the possibility that NRAGE may facilitate apoptosis induced by receptors other than p75NTR. Together, these studies demonstrate that NRAGE plays an important role in apoptotic-signaling in vivo. Cell Death and Differentiation (2008) 15, 1921-1929 doi:10.1038/cdd.2008; published online 5 September 2008The p75 neurotrophin receptor (p75NTR) is a TNF receptor superfamily member that is expressed at high levels during embryogenesis and functions as a pro-apoptotic receptor during the development of neuronal and non-neuronal tissues.

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-The effects of breed and season on histological skin characteristics were studied at the experimental facilities of INRA in Guadeloupe (16• Lat. N., 61• Long. W.) in two replicates using a total of 20 Creole (CR) and 20 Large White (LW) pigs. The first replicate was carried out during the warm season (i.e., between February and April) and the second during the hot season (i.e., between August and October). In the warm season, ambient temperature and relative humidity averaged 25.3• C and 86.0%, respectively. The corresponding values for the hot season were 27.9• C and 83.6%. At 90 kg BW, all pigs were slaughtered and a 2 to 4 cm 2 sample of cutaneous tissue from the back region (i.e., at the last dorsal rib level) was taken from each animal before scalding and dehairing. Slices were stained with trichrome blue staining and the thickness of the epidermis and dermis were determined. The density and surface of the sweat glands (SG) were also determined. The mast cell density was measured using slices stained with Giemsa. Epidermis thickness was not affected by breed or season and averaged 55 µm. However, dermis thickness was significantly higher in CR than in LW pigs (3.60 vs. 3.13 mm; P < 0.01) but it was not influenced by season (3.36 mm on average; P = 0.17). The density of SG was significantly higher in CR than in LW pigs (32.0 vs. 25.4 SG per mm 2 ; P < 0.01) but their surface area was lower in CR than in LW pigs (106 vs. 263 × 10 −3 µm 2 per mm 2 ; P < 0.01). The SG density tended to be higher in the hot than in the warm season (30.4 vs. 26.9 SG per mm 2 ; P = 0.0971). Mast cell density in the dermis was found to be higher in CR than in LW pigs (2.52 vs. 1.38 mast cells per mm 2 ; P < 0.01). Irrespective of the breed, mast cell density was higher during the hot than the warm season (2.22 vs. 1.68 mast cells per mm 2 ; P < 0.01). In conclusion, our study suggests that the differences in skin histology and/or sweat gland histometry could partly explain the better heat tolerance in CR pigs. • C et 86,0 %. Les valeurs correspondantes pour la saison chaude étaient de 27,9• C et 83,6 %. Au poids vif de 90 kg, tous les porcs ont été abattus et un échantillon de peau de 2 à 4 cm 2 a été prélevé au niveau du dos (i.e., au niveau de la dernière côte dorsale) avant l'échaudage et l'épilation. Les épaisseurs de l'épiderme et du derme ont été déterminées sur des coupes de peau colorées au trichrome bleu. La densité et la surface des glandes sudoripares (SG) ont également été mesurées. La densité des mastocytes a été déterminée sur des coupes colorées au Giemsa. L'épaisseur de l'épiderme n'est pas affectée par le type génétique ou par la saison (55 µm en moyenne). En revanche, l'épaisseur du derme est significativement plus importante chez le CR comparativement au LW (3,60 vs. 3,13 mm ; P < 0,01) mais n'est pas influencée par la saison (3,36 mm en moyenne ; P = 0,17). La densité des glandes sudoripares est significativement plus importante chez le porc CR par rapport au LW (32,0 vs. 25,4 SG par mm 2 ; P < 0,01) m...

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