James E. Tarara

Collagen type I hydrogel allows migration, proliferation, and osteogenic differentiation of rat bone marrow stromal cells

Hydrogels are potentially useful for many purposes in regenerative medicine including drug and growth factor delivery, as single scaffold for bone repair or as a filler of pores of another biomaterial in which host mesenchymal progenitor cells can migrate in and differentiate into matrix-producing osteoblasts. Collagen type I is of special interest as it is a very important and abundant natural matrix component. The purpose of this study was to investigate whether rat bone marrow stromal cells (rBMSCs) are able to adhere to, to survive, to proliferate and to migrate in collagen type I hydrogels and whether they can adopt an osteoblastic fate. rBMSCs were obtained from rat femora and plated on collagen type I hydrogels. Before harvest by day 7, 14, and 21, hydrogels were fluorescently labeled, cryo-cut and analyzed by fluorescent-based and laser scanning confocal microscopy to determine cell proliferation, migration, and viability. Osteogenic differentiation was determined by alkaline phosphatase activity. Collagen type I hydrogels allowed the attachment of rBMSCs to the hydrogel, their proliferation, and migration towards the inner part of the gel. rBMSCs started to differentiate into osteoblasts as determined by an increase in alkaline phosphatase activity after two weeks in culture. This study therefore suggests that collagen type I hydrogels could be useful for musculoskeletal regenerative therapies.

Casp8p41 generated by HIV protease kills CD4 T cells through direct Bak activation

HIV protease converts procaspase 8 into Casp8p41, which binds and activates Bak to induce cell death in infected CD4 T cells.

Clustering of the B Cell Receptor Is Not Required for the Apoptotic Response

We examined the role of BCR cell membrane redistribution in anti-IgM-induced apoptosis in three human B cell lines, RA#1, 2G6, and MC116, that differ in their relative levels of sIgM expression. The apoptotic response was found to be dependent on the nature of the anti-IgM and the cell line. In the cell lines, RA#1 and MC116, sIgM aggregated into patches that were insensitive to the disruption of cholesterol-rich membrane microdomains by nystatin or beta-MCD. The B cell line 2G6 was able to reorganize sIgM into a tight coalescent cap upon anti-IgM treatment. However, in this case, the lipid raft inhibitors nystatin and beta-MCD disrupted the patching. In 2G6 cells, BCR-mediated apoptosis was not affected by nystatin treatment, whereas it increased in beta-MCD pretreated cells. Thus, no evident correlation was found between apoptosis and BCR cell membrane redistribution or lipid raft formation in either of the three cell lines. The data indicate that the apoptotic signal transduction pathway is independent of BCR translocation into lipid rafts and/or aggregation.

Three-dimensional structure of neurons from peripheral autonomic ganglia using confocal microscope images

An understanding of neuronal physiology at the single unit level requires knowledge of the functional properties of the neurons as well as a detailed description of its morphology. A full morphological description should include a three-dimensional (3-D) analysis. In this paper, we describe for the first time, 3-D morphology of individual neurons of the peripheral autonomic nervous system intact within whole-mount preparations. Neurons were filled with the fluorescent dye Lucifer Yellow and imaged by laser scanning confocal microscopy. Three- dimensional reconstructions were obtained using volume rendering methods on a set of serial optical sections obtained for each neuron. The 3-D images of the neurons we studied showed a complexity of shape and detail that is not readily apparent from images viewed by traditional microscopy.

Microvessel density and VEGF expression in pituitaries of pregnant women

OBJECTIVE: In pregnant women, the pituitary is enlarged and the prolactin (PRL) secreting cells increase in size and number. This PRL cell hyperplasia is associated with hyperprolactinemia. The aim of the present work was to investigate adenohypophysial vascularization and immunoexpression of vascular endothelial growth factor (VEGF) in pituitaries of pregnant and post-partum women and compare the results with age-matched adenohypophyses of non-pregnant women who had no endocrine diseases. DESIGN: Pituitaries (n=18) obtained by autopsy from female patients of reproductive age who had died during pregnancy, after abortion or during post-partum were immunostained for CD-34 and VEGF using the streptavidinbiotin-peroxidase complex method. RESULTS: The results showed that microvessel densities and VEGF immunoexpression in the adenohypophyses of pregnant and post-partum women were similar to those found in the control pituitaries. CONCLUSION: It can be concluded that pituitary enlargement and PRL cell hyperplasia in pregnant women may occur without neovascularization and increased VEGF immunoexpression.