SUMMARY Thrombospondin-1 (TSP-1) and an alternatively spliced fibronectin (Fn)-EIIIA isoform are adhesive proteins associated with embryogenesis and tissue remodeling. We compared, by immunohistochemistry and in situ hybridization, the course of TSP-1 and Fn-EIIIA expression in a model of glomerulonephritis induced by Habu snake venom (HV) and characterized by mesangial cell migration, proliferation, and extracellular matrix (ECM) synthesis. At 24 hr after HV, TSP-1 and Fn-EIIIA proteins localized in the central aspects of lesions associated with platelets and macrophages and at the margins of lesions coinciding with mesangial cell migration (determined by Thy-1 staining). Mesangial cells at this time expressed TSP-1 but not Fn-EIIIA mRNA. TSP-1 protein and mRNA peaked in lesions at 48 hr and were associated with cell proliferation (determined by PCNA, ␣-smooth muscle actin phenotype, and expression of ␤-PDGF receptor mRNA). TSP-1 expression declined at 72 hr when expression of ECM synthesis peaked, as determined by increased expression of collagen Type IV, laminin, and TGF-␤ 1 protein and mRNA. Mesangial cell expression of Fn-EIIIA was first observed at 48 hr and was most abundant at 72 hr after HV. Therefore, plateletand macrophage-derived Fn-EIIIA and TSP-1 in early lesions are associated with mesangial cell migration. Mesangial cell upregulation of TSP-1 is associated with migration and proliferation but not maximal ECM accumulation, whereas mesangial cell expression of Fn-EIIIA is associated with proliferation and ECM accumulation. These results suggest distinctive temporal and spatial roles for TSP-1 and Fn-EIIIA in remodeling during glomerular disease. Thrombospondin-1 (TSP-1) and cellular fibronectin, particularly the alternatively spliced isoform containing an extradomain EIIIA (Fn-EIIIA), are highly expressed during embryogenesis (ffrench-Constant and

In this study we examined if an association exists between expression of an alternatively spliced "embryonic" fibronectin isoform EIIIA (Fn-EIIIA) and alpha-smooth muscle actin (alpha-SMA) in the maturing and adult rat kidney and in two unrelated models of glomerular disease, passive accelerated anti-glomerular basement membrane (GBM) nephritis and Habu venom (HV)-induced proliferative glomerulonephritis, using immunohistochemistry and in situ hybridization. Fn-EIIIA and alpha-SMA proteins were abundantly expressed in mesangium and in periglomerular and peritubular interstitium of 20-day embryonic and 7-day (D-7) postnatal kidneys in regions of tubule and glomerular development. Staining was markedly reduced in these structures in maturing juvenile (D-14) kidney and was largely lost in adult kidney. Expression of Fn-EIIIA and alpha-SMA was reinitiated in the mesangium and the periglomerular and peritubular interstitium in both models and was also observed in glomerular crescents in anti-GBM nephritis. Increased expression of Fn-EIIIA mRNA by in situ hybridization corresponded to the localization of protein staining. Dual labeling experiments verified co-localization of Fn-EIIIA and alpha-SMA, showing a strong correlation of staining between location and staining intensity during kidney development, maturation, and disease. Expression of EIIIA mRNA corresponded to protein expression in developing and diseased kidneys and was lost in adult kidney. These studies show a recapitulation of the co-expression of Fn-EIIIA and alpha-SMA in anti-GBM disease and suggest a functional link for these two proteins.

Pericellular proteolysis involves the plasminogen activatorlplasmin system and plays an important role in cell remodeling involving cell migration and extracellular materized a model of proliferative glomerulonephritis induced by Habu snake venom (HSV) in the rat that involves cell migration, pml&eration, and extracellular matrix accumulation. Because-plasminogen activator-inhibitor-1 (PAI-1) has been used as a marker for cell migration as well as matrix accumulation, we wexe interested in examhing the temporal and spatial expression and cellular sources of PAI-1 mRNA and translated protein Over the course of HSV-induced prolifesative glomerulonephritis. The results showed a highly localized and progressive expression of PAI-1 mRNA and translated protein by in situ hybridization and immunohistochemistry at the margins and periphery of glomerular lesions 8 and 24 hr after HSV. The expression of PAI-1 in aixtumover. studiesinthislaboratoryhavepreviodycharac-

The purpose of this study was to determine what motivated nontraditional students to go into teaching and reveal why they were sure, by their second year of experience, that they would stay in teaching. This study used the "participant as ally-essentialist approach" [1] to understand the participants' stories. The primary data source was focus groups and one to three one-on-one follow-up interviews with nine participants who were second-year nontraditional elementary or middle school teachers. Each participant entered the profession by the same program, and all of the participants came from the same site. Their ages ranged between 22 and 45 years. The researcher [2] developed eight portraits of participants who talked about their career progression. These portraits yielded three major findings. First, the participants revealed their commitment to teaching, generally planning to stay in the career until they retired. Another major aspect in the portraits was that many of the participants used their earlier life experience and maturity in their classrooms. The last major finding revealed that a significant proportion of teachers found the profession by accident. The results of this study suggest that, with increasing numbers of nontraditional students, teacher education programs need to take into account the assignments, delivery methods, and class content. When placing teachers in schools for internships and student teaching, the coordinator should be aware of their status. In addition, school districts should be aware that this population is committed to adding value to the school as soon as they arrive.

No abstract