Merkel Cells as Putative Regulatory Cells in Skin Disorders: An In Vitro Study

Merkel cells (MCs) are involved in mechanoreception, but several lines of evidence suggest that they may also participate in skin disorders through the release of neuropeptides and hormones. In addition, MC hyperplasias have been reported in inflammatory skin diseases. However, neither proliferation nor reactions to the epidermal environment have been demonstrated. We established a culture model enriched in swine MCs to analyze their proliferative capability and to discover MC survival factors and modulators of MC neuroendocrine properties. In culture, MCs reacted to bFGF by extending outgrowths. Conversely, neurotrophins failed to induce cell spreading, suggesting that they do not act as a growth factor for MCs. For the first time, we provide evidence of proliferation in culture through Ki-67 immunoreactivity. We also found that MCs reacted to histamine or activation of the proton gated/osmoreceptor TRPV4 by releasing vasoactive intestinal peptide (VIP). Since VIP is involved in many pathophysiological processes, its release suggests a putative regulatory role for MCs in skin disorders. Moreover, in contrast to mechanotransduction, neuropeptide exocytosis was Ca2+-independent, as inhibition of Ca2+ channels or culture in the absence of Ca2+ failed to decrease the amount of VIP released. We conclude that neuropeptide release and neurotransmitter exocytosis may be two distinct pathways that are differentially regulated

Análise de dados de reclamações em empreendimentos habitacionais de interesse social: estudo no Programa de Arrendamento Residencial

O gerenciamento de reclamações é uma prática difundida em muitas emmpresas do setor de manufatura, a fim de proporcionar a melhoria da ualidade de produtos e serviços. No que tange à construção civil, bservam-se poucos estudos sobre a utilização desse tipo de gestão de empreendimentos, sendo poucas as empresas que percebem a utilidade das informações sobre reclamações. O presente trabalho apresenta uma análise de dados de reclamações de usuários de uma amostra de empreendimentos habitacionais de interesse social, com o objetivo de investigar sua utilidade para a retroalimentação do processo de desenvolvimento do produto nesse segmento. Foram analisadas 6.956 reclamações de usuários de 42 empreendimentos habitacionais de interesse social do Programa de Arrendamento Residencial, localizados no estado do Rio Grande do Sul. O trabalho envolveu um tratamento inicial dos dados de reclamações para a montagem de um banco de dados, seguido da aplicação de diversos testes estatísticos. As principais contribuições estão relacionadas com a utilidade dos dados de reclamações, incluindo a geração de indicadores que podem apoiar a tomada de decisão por parte de diferentes agentes envolvidos na produção habitacional, tais como projetistas, construtoras, agentes financiadores e empresas envolvidas na gestão da operação e manutenção. Os indicadores, se bem utilizados, podem contribuir para a melhoria de produtos e serviços que compreendem os empreendimentos habitacionais, possibilitando um aumento na satisfação dos usuários finais

The liquid–solid transition in a micellar solution of a diblock copolymer in water

The structure of a diblock copolymer solution in the vicinity of the transition between micellar liquid and solid phases was investigated using small-angle x-ray scattering (SAXS). An amphiphilic poly(oxyethylene)–poly(oxybutylene) diblock was studied in water. Static and dynamic light scattering techniques were used to provide an independent measure of micelle dimensions and aggregation number. Dynamic shear rheometry and mobility measurements were used to locate phase transitions. A micellar liquid phase was identified at low concentration and a cubic micellar phase at higher concentration, the transition between the two occurring at higher temperature as the concentration increased. The cubic micellar phase behaves rheologically as a solid and SAXS confirmed a face-centered cubic structure. Intermediate between these two phases, a viscoelastic soft solid was observed, with a finite yield stress but with a much lower dynamic modulus than the crystalline solid. Several distinct suggestions have been put forward for the structure of the solution in this region. In a poly(oxyethylene)–poly(oxypropylene)–poly(oxyethylene) Pluronic triblock, small-angle neutron scattering and rheology provided evidence for a percolation transition between micellar liquid and solid phases [L. Lobry et al., Phys. Rev. E. 60, 7076 (1999)], indicating a fractal structure of micelles aggregated due to attractive interactions. Alternatively, a defective solid phase has been proposed. We analyzed the structure of solutions of our diblock copolymer via detailed model fits to the SAXS data for concentrations spanning the liquid–solid transition. The micellar form factor was modeled as a homogeneous micellar core with attached Gaussian chains; and the intermicellar structure factor could be described using the hard sphere model. Thus there is no evidence for percolation induced by effective attractive interactions between micelles in our system. In contrast SAXS data indicates there is a coexistence region between hard sphere fluid and solid crystal phases, in which small grains of close-packed crystal coexist with fluid. It is apparent that block copolymer micelles acts as model colloidal systems in which it is possible to investigate the influence of attractive and repulsive interactions between spherical particles by varying the copolymer compositio

Rheology and structures of aqueous gels of triblock(oxyethylene/osybutylene/oxyethylene) copolymers with lengthy oxyethylene blocks

Four EBE copolymers (E ) oxyethylene repeat unit, B ) oxybutylene repeat unit) based on a B20 central block and end blocks ranging from 58 to 260 E units were studied. Rheological measurements (oscillatory and steady shear) were used to confirm gel boundaries (previously explored by a tube inversion method) and to determine storage and loss moduli (G¢ and G¢¢) and yield stresses (óy) for aqueous gels formed at copolymer concentrations below 20 wt %. The phase diagrams contained a region of hard gel (G¢ > G¢¢, high G¢ and óy), an extensive region of soft gel ((G¢ > G¢¢, low G¢ and óy), denoted 1, and a second region of soft gel at low temperatures, denoted 2. Small-angle X-ray scattering was used to probe the hard gel structure. Concentrated aqueous gels (20 wt %) had a body-centered cubic (bcc, Im3hm) structure. The structure of dilute gels near to the hard gel boundary was not defined, although the Im3hmand Pm3hn cubic structures were eliminated. Depending on concentration, the soft gels were assigned either to percolationinduced fractal structures (soft gel 1) or to defective cubic structures (soft gels 1 and 2)