Association of the p85 regulatory subunit of phosphatidylinositol 3- kinase with an essential erythropoietin receptor subdomain

Using an active, HAI epitope-tagged form of the murine erythropoietin (EPO) receptor and via direct coimmunoprecipitation, the p85 regulatory subunit of phosphatidyl inositol-3 kinase (p85/PI3-K) is shown to associate with the EPO receptor in transfected FDC-P1 cell lines. Coimmunoprecipitation of p85 with epitope-tagged EPO receptors was observed initially in FDC-HER cells labeled metabolically with [32P]orthophosphate, and association of these factors was confirmed by Western analyses of receptor immunoprecipitates using p85 antiserum. Interestingly, this association occurred in the absence of ligand, and exposure of FDC-HER cells to EPO did not detectably affect levels of receptor-associated p85 or overall levels of p85 phosphorylation. However, EPO was observed to stimulated the rapid formation of phosphatidylinositol 32P-phosphate in FDC-HER and FDC-ER cells. Through baculovirus-mediated expression of epitope-tagged EPO receptor forms in SF9 cells, domains for p85 association were mapped. Analyses of receptor forms with cytosolic truncations and deletions delineated a candidate subdomain for p85 binding to an essential extended box-2 region (P329-E374; including a putative motif for SH2 binding, Y343LVL). These findings extend a mechanistic alignment between the EPO receptor and protein tyrosine kinase-encoding receptors that likewise activate PI3-K, and expand the importance of further defining pathways to PI3-K activation.     

Steroid-induced dermal thinning: discontinuous application of clobetasol-17-propionate ointment.

The skin thinning effect of discontinuous topical clobetasol-17-propionate applications was tested in human volunteers. Application frequencies were daily (1/0), every third day (1/2), every fifth day (1/4), every seventh day (1/6) and every ninth day (1/8). Clobetasol-17-propionate was administered topically under occlusion for 1 h. The treatment period was 41 days. There were no differences of the skin thinning effect of daily and 1/2 administration. The skin thinning effect of 1/4, 1/6 and 1/8 was smaller but also significant compared to controls. The curves demonstrating skin thinning effects initially were dropping off and reached a plateau within about 2 weeks. After finishing application, skin thickness normalized within 2 weeks. Because of these findings, a treatment interval of 3 days is discussed as therapeutically efficient.     

Histamine upregulates keratinocyte MMP-9 production via the histamine H1 receptor

Skin inflammation and the migration of cells at the site of the immune response play an important role in allergic skin diseases. It has already been described that matrix metalloproteinase 9 (MMP-9) influences tissue remodeling and facilitates cell migration by proteolytic degradation of basal membrane components. The aim of this study was to investigate MMP-9 expression on human primary keratinocytes (KCs) upon stimulation with histamine, a potent mediator in allergic responses. With ELISA and zymography, we could show that histamine induced dose-dependent upregulation of MMP-9 in cultured KCs and in punch biopsies of human skin. The histamine H(1) receptor (H(1)R) agonist beta-histine-but not agonists for H(2)R, H(3)R, and H(4)R-induced MMP-9, whereas the H(1)R antagonist clemastine blocked the effect in a dose-dependent manner. Immunohistological staining showed that histamine-induced MMP-9 led to destruction of type IV collagen at the basement membrane in healthy skin. In a coculture system of KCs and T cells, migration of T cells through an artificial basement membrane was increased after histamine stimulation of KCs. Our findings demonstrate enhanced MMP-9 production and cell migration after histamine stimulation and may represent a new mechanism by which KCs contribute to the pathology of skin diseases.     

Mood change after anaesthesia with remifentanil or alfentanil

BACKGROUND AND OBJECTIVE: There are anecdotal reports of dysphoria occurring in patients on the first day after anaesthesia with remifentanil. This study was performed to investigate this allegation and to find a possible relationship to postoperative shivering or to nausea and vomiting. METHODS: Patients undergoing otorhinolaryngeal surgery took part in a prospective, randomized, double-blind study comparing total intravenous anaesthesia with propofol (2 mg kg(-1) bolus injection then 100 microg kg(-1) min(-1)) and remifentanil (1 microg kg(-1) bolus then 0.1-0.5 microg kg(-1) min-1) or alfentanil (30 microg kg(-1) bolus then 0.16-0.83 microg kg((-1) min(-1)). The patients were carefully insulated and actively warmed by convective heating and rectal temperature was monitored continuously. Postoperative shivering was graded on a three-point scale, and the cumulative incidence of nausea and vomiting were registered at 24 h after surgery. Pre- and postoperative mood was measured with the von Zerssen mood scale (Befindlichkeits-Skala) and changes tested for significance. High scores reflect discontent and dysphoria. RESULTS: The data of 98 patients (49 in each group, ASA I-II, age 42 +/- 13 yr, anaesthesia time 141 +/- 60 min; mean +/- SD; intergroup P values > 0.1) were evaluated. Core temperature did not change perioperatively (before 36.6 +/- 0.2 degrees C; after 36.8 +/- 0.3 degrees C, inter- and intragroup P > 0.1). The incidence of nausea was the same in each group; vomiting occurred with equal frequency (6/49 vs. 7/49). Shivering was significantly more frequent after remifentanil (41% vs. 10%, P < 0.001). The patients' mood remained stable after remifentanil but worsened after alfentanil (von Zerssen score from 9.3 +/- 2.5 to 13.9 +/- 3.6; mean +/- 95% confidence intervals; P < 0.01). DISCUSSION: Postoperative shivering was more frequent after remifentanil but was unrelated to intraoperative heat loss. Contrary to preliminary informal observations, there was no evidence that remifentanil caused postanaesthetic dysphoria on the day one after surgery.