Hepatocyte growth factor receptor, c-Met, in human embryo salivary glands. An immunohistochemical study.

Salivary gland morphogenesis involves complex, coordinated events that include epithelial-mesenchymal interactions. Mesenchymal-epithelial transition factor (c-Met) is the hepatocyte growth factor (HGF) receptor. The latter is a hepatotropic factor originally identified in rat serum and platelets. It is essential in fetal tissue development, where it regulates complex morphogenetic processes including extracellular matrix invasion, cell migration, cell polarization and tubulogenesis. The c-Met/HGF system is believed to participate in epithelial-mesenchymal interactions during development. Twelve human embryonic minor salivary glands were studied by immunohistochemistry to investigate the role of c-Met in human salivary gland development. Strong c-Met immunopositivity in the glands demonstrated that the molecule is involved in their development and suggested a role for the c-Met/HGF system in this process.

Expression of vascular endothelial growth factor in human dysfunctional temporomandibular joint discs.

A high density of blood vessels is found in specimens of temporomandibular joint (TMJ) disc at any stage of internal derangement of the joint, but the factors responsible for angiogenesis in the disc have not been described. The purpose here was to investigate, in human TMJ discs, the expression of vascular endothelial growth factor (VEGF), a multifunctional cytokine that contributes to angiogenesis. Specimens, free of significant morphological alterations and with varying degrees of disc tissue degeneration/regeneration, were studied by immunohistochemistry for VEGF in order to correlate immunohistochemical with histopathological findings. In normal discs and discs with minor pathological changes, fibroblast-like cells, fibrochondrocytes and chondrocyte-like cells were either not or only weakly immunostained by VEGF antibody. In disc specimens from internal derangement of the TMJ with significant tissue degeneration/regeneration, VEGF was consistently expressed. In these specimens, immunoreaction products for VEGF were observed both in the disc and in the endothelial cells of newly formed vessels. This VEGF immunolocalization is consistent with the stimulation of angiogenesis and the morphogenesis and differentiation of chondrocytes. Therefore VEGF expression by disc chondrocyte-like cells might reflect the action of the cytokine as an inducer of angiogenesis and as an autocrine signal for cells of the chondrogenic lineage.

[Cutaneous histopathologic changes in laboratories working in the processing of petroleum]. / Modificazioni isotopatologiche cutanee in lavoratori addetti alla movimentazione di prodotti petroliferi.

Petroleum and its derivatives are a complex mixture of many constituents in varying proportions, such as polycyclic aromatic hydrocarbons, alcohols, ethers and additives. It is well established that petroleum derivatives are absorbed through the skin but exposure has not been quantified. Manifestations of cutaneous exposure vary from squamous cell carcinoma to irritative contact dermatitis such as occurs in the workplace. The aim of the investigation was to evaluate cutaneous histomorphological alterations in a group of 10 healthy workers occupationally exposed to repeated and low amounts of gasoline for a prolonged period. Histological examination and immunocytochemical techniques were performed after taking punch biopsies. The results showed the presence of perivascular lympho-plasma cell infiltration and leucocyte cells scattered in the dermal layer. A mild increase in epidermal Langerhans cells was also observed while the detection of the Ki-67 antigen in keratinocytes gave a normal appearance. In conclusion, the overall histomorphological and immunological features was not specific, but resembled skin reactions due to several irritative agents. Such skin alterations can lead to contact dermatitis.