Endothelin-1 stimulates human colonic myofibroblast contraction and migration.

BACKGROUND: Although the contractile, migratory, and proliferative responses of subepithelial myofibroblasts to injury have been postulated to be important events in intestinal wound healing, contractile force generation and migration by these cells has not been investigated previously, and the signals that regulate proliferation by these cells are poorly understood. AIMS: The primary aim of this study was to test the hypothesis that the inflammatory mediator endothelin-1 modulates contraction, migration, and proliferation of intestinal myofibroblasts. We also sought to examine the signal transduction pathways which might underlie these putative effects. METHODS: Contraction, migration, proliferation, cytosolic [Ca(2+)], and myosin phosphorylation were measured in human colonic subepithelial myofibroblasts in the absence and presence of endothelin receptor agonists and antagonists. RESULTS: Endothelin-1, but not interleukin 1 alpha, interleukin 6, interleukin 8, interleukin 10, or tumour necrosis factor alpha, induced a rapid and robust generation of contractile force, which was associated with an increase in cytosolic [Ca(2+)] and myosin phosphorylation. Inhibition of rho associated kinase reduced endothelin-1 stimulated myosin phosphorylation and contractile force development. Endothelin-1 stimulated migration with a dose-response relationship similar to that observed for contraction. Endothelin A and B receptors mediated contraction while migration was mediated predominantly through endothelin B receptors. Platelet derived growth factor and serum, but not endothelin-1, induced proliferation. CONCLUSIONS: Endothelin-1 stimulates colonic subepithelial myofibroblast contraction and migration via endothelin receptor mediated myosin phosphorylation. These results support an important role for subepithelial myofibroblasts in the injury response of the gut and consequently intestinal wound repair.

RhoA/rho-associated kinase mediates fibroblast contractile force generation.

The intracellular signals governing contractile force generation by non-muscle cells remain uncertain. Our aim was to test the hypothesis that the rhoA/rho-associated kinase signaling pathway is a principal mediator of contractile force generation in non-muscle cells. We measured myosin II regulatory light chain (MLC) phosphorylation and directly quantitated force generation by chicken embryo fibroblasts in the absence and presence of selective inhibitors of rhoA, and its downstream effector, rho-associated kinase. Inactivation of rhoA, with C3 transferase, inhibited serum-stimulated MLC phosphorylation and contractile force generation. Y-27632, an inhibitor of rho-associated kinase, reduced basal contractile tension, and inhibited both serum and endothelin-1 stimulated MLC phosphorylation and contractile force generation. The results of this study provide novel evidence indicating that the rhoA/rho-associated kinase signaling pathway is a principal mediator of MLC phosphorylation and consequent contractile force generation by non-muscle cells.

Characteristics and outcome of endometrial carcinoma patients age 45 years and younger.

Recent reports have suggested that the pathologic features of young patients with endometrial cancer are less favorable than previously thought. We retrospectively reviewed the characteristics and outcome of young patients with endometrial cancer at our institution. A total of 457 surgically staged patients were divided in 2 groups: Group A (age < or =45 years, n = 41) and B (age >45, n = 416). Groups A and B had a similar distribution of tumor stage, grade, histology, lymphovascular invasion, synchronous ovarian primaries, and positive cytology. Although group A tumors had less myometrial invasion (MI) (p = 0.004) and were lower grade (p = 0.06), a trend to more frequent nodal involvement was seen in group A women (p = 0.09). Adverse pathologic features, in particular deep MI, were more common in group A patients older than age 40. Group A patients had a disease-free (p = 0.56) and cause-specific (p = (0.26) survival that was similar to that of group B patients. Young patients with endometrial cancer have a distribution of most pathologic features and equivalent outcome similar to that of older women. However, adverse features are not equally distributed in young women. A discordance may also exist between MI, grade, and nodal involvement.

Probenecid reverses multidrug resistance in multidrug resistance-associated protein-overexpressing HL60/AR and H69/AR cells but not in P-glycoprotein-overexpressing HL60/Tax and P388/ADR cells.

PURPOSE: To determine whether probenecid, an inhibitor of organic anion transport, is able to reverse multidrug resistance (MDR) through modulation of the drug transport function of MDR-associated protein (MRP) and P-glycoprotein (P-gP). METHODS: Two MRP-overexpressing cell lines (HL60/AR and H69/AR) and two P-gP-overexpressing cell lines (HL60/Tax and P388/ADR) were cultured with different concentrations of daunorubicin (DNR) or vincristine (VCR) in the presence or absence of various concentrations of probenecid (0.01-10 mM). Drug sensitivity was determined using an MTT assay. DNR accumulation and subcellular distribution were determined by flow cytometry and confocal microscopy respectively. VCR accumulation was determined by scintillation spectrometry. RESULTS: Probenecid, in a concentration-dependent manner, reversed resistance to DNR and VCR in HL60/AR and H69/AR tumor cell lines. This effect of probenecid on MDR was associated with an increased accumulation of DNR and VCR and correction of the altered subcellular distribution of DNR. The concentrations of probenecid that reversed MDR are clinically achievable in vivo. In contrast, probenecid did not reverse MDR in either HL60/Tax or P388/ADR tumor cell lines that overexpress P-gP. CONCLUSION: These results suggest that probenecid is an effective chemosensitizer of MRP-associated MDR tumor cells and is a potential candidate for clinical use to reverse MDR.

Remittances from labor migration: evaluations, performance and implications.

2 evaluative views of worker remittances draw opposite conclusions. The negative one posits that remittances increase dependency, contribute to economic and political stability and development distortion, and lead to economic decline that overshadows a temporary advantage for a fortunate few. The positive view sees remittances as an effective response to market forces, providing a transition to an otherwise unsustainable development. They improve income distribution and quality of life beyond what other available development resources could deliver. The implications are tested for labor supply countries to Europe and the Middle East. The implications of the negative are not supported. Although the dire predictions of the pessimistic view have not materialized, the converse - contributions of remittances to economic performance - should not be overstated due to a lack of data.