The Epithelial Sodium Channel and the Processes of Wound Healing.

The epithelial sodium channel (ENaC) mediates passive sodium transport across the apical membranes of sodium absorbing epithelia, like the distal nephron, the intestine, and the lung airways. Additionally, the channel has been involved in the transduction of mechanical stimuli, such as hydrostatic pressure, membrane stretch, and shear stress from fluid flow. Thus, in vascular endothelium, it participates in the control of the vascular tone via its activity both as a sodium channel and as a shear stress transducer. Rather recently, ENaC has been shown to participate in the processes of wound healing, a role that may also involve its activities as sodium transporter and as mechanotransducer. Its presence as the sole channel mediating sodium transport in many tissues and the diversity of its functions probably underlie the complexity of its regulation. This brief review describes some aspects of ENaC regulation, comments on evidence about ENaC participation in wound healing, and suggests possible regulatory mechanisms involved in this participation.

Hepatic hemangioendothelioma associated with production of humoral thyrotropin-like factor.

We report on 7 patients referred for treatment of hepatic hemangioendothelioma with increased thyrotropin levels. The serum thyroxine level was decreased in 4 and increased in 2. Immunohistochemistry showed positive staining of tumor, but not of normal liver tissue, for thyrotropin. We propose secretion by the tumor of a thyrotropin-like factor.

Epithelioid hemangioendothelioma of the liver: report of two cases.

This report describes two patients with hepatic epithelioid hemangioendothelioma: a 33-year-old woman and a 28-year-old man. The first case presented with a palpable abdominal mass and has survived without treatment for 6 years since diagnosis, with ascites but a good general condition. The other patient presented with abdominal pain and cholestasis. He had a rapid course and death occurred 6 months after the onset of symptoms. Histologically the tumors consisted of a proliferation of neoplastic cells with an angiogenic tendency embedded in a myxohyaline stroma. Positivity for the factor VIII-related antigen, for UEA-I and for vimentin and negativity for keratin of the neoplastic cells in the immunohistochemical investigation permitted identification of their endothelial origin. In both cases, the initial diagnosis was erroneous.