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Neuron. 2000 Oct;28(1):273-85.
A targeted deletion in alpha-tectorin reveals that the tectorial membrane is required for the gain and timing of cochlear feedback.
Legan PK, Lukashkina VA, Goodyear RJ, Kossi M, Russell IJ, Richardson GP.
School of Biological Sciences, The University of Sussex, Falmer, Brighton, United Kingdom.
alpha-tectorin is an extracellular matrix molecule of the inner ear. Mice homozygous for a targeted deletion in a-tectorin have tectorial membranes that are detached from the cochlear epithelium and lack all noncollagenous matrix, but the architecture of the organ of Corti is otherwise normal. The basilar membranes of wild-type and alpha-tectorin mutant mice are tuned, but the alpha-tectorin mutants are 35 dB less sensitive. Basilar membrane responses of wild-type mice exhibit a second resonance, indicating that the tectorial membrane provides an inertial mass against which outer hair cells can exert forces. Cochlear microphonics recorded in alpha-tectorin mutants differ in both phase and symmetry relative to those of wild-type mice. Thus, the tectorial membrane ensures that outer hair cells can effectively respond to basilar membrane motion and that feedback is delivered with the appropriate gain and timing required for amplification.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11087000&dopt=Abstract
Pharm Res. 2000 Sep;17(9):1092-7.
Evaluation of a human bio-engineered skin equivalent for drug permeation studies.
Asbill C, Kim N, El-Kattan A, Creek K, Wertz P, Michniak B.
Department of Basic Pharmaceutical Sciences, College of Pharmacy, University of South Carolina 29208, USA.
PURPOSE: To test the barrier function of a bio-engineered human skin (BHS) using three model drugs (caffeine, hydrocortisone, and tamoxifen) in vitro. To investigate the lipid composition and microscopic structure of the BHS. METHODS: The human skin substitute was composed of both epidermal and dermal layers, the latter having a bovine collagen matrix. The permeability of the BHS to three model drugs was compared to that obtained in other percutaneous testing models (human cadaver skin, hairless mouse skin, and EpiDerm). Lipid analysis of the BHS was performed by high performance thin layered chromatography. Histological evaluation of the BHS was performed using routine H&E staining. RESULTS: The BHS mimicked human skin in terms of lipid composition, gross ultrastructure, and the formation of a stratum corneum. However, the permeability of the BHS to caffeine, hydrocortisone, and tamoxifen was 3-4 fold higher than that of human cadaver skin. CONCLUSIONS: In summary, the results indicate that the BHS may be an acceptable in vitro model for drug permeability testing.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11087041&dopt=Abstract
Pathol Res Pract. 2000;196(10):675-81.
Transthyretin and transferrin in hemangioblastoma stromal cells.
Bleistein M, Geiger K, Franz K, Stoldt P, Schlote W.
Department of Neuropathology, Philipps-University, Marburg, Germany.
Hemangioblastoma, a rare benign tumor of the CNS, consists of two main components: capillaries and stromal cells. Despite many efforts, the histogenesis of stromal cells is still unknown. We took a new approach to clarify the origin of stromal cells using immunohistochemical methods. Paraffin-embedded tissue of 24 surgically removed hemangioblastomas of the CNS was examined with antibodies against transthyretin, transferrin, vimentin, NSE, protein S-100, CK 8, KL-1, EMA, CD34, factor VIII rAg, and collagen IV. Stromal cells showed a positive reaction with anti-transthyretin in 12 of 24 hemangioblastomas, a positive reaction with anti-transferrrin, to a different extent, in 13 of 24 cases, and many stromal cells expressed basal membrane collagen IV on the cell surface in 19 of 24 cases. The expression of transthyretin and transferrin in stromal cells of hemangioblastomas is reported for the first time, thus providing an antigenic profile of hemangioblastoma stromal cells that is very similar to that of immature choroid plexus epithelium. These findings support the notion that hemangioblastoma stromal cells may originate from the embryonal plexus epithelium. We discuss our results with special regard to stromal cell histogenesis, including a review of the literature.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11087054&dopt=Abstract
Pathol Res Pract. 2000;196(10):701-11.
Adhesive and invasive features in gliomas.
Tews DS.
Division of Neuropathology, Medical Center, Johannes Gutenberg University, Mainz, Germany. tewail.Uni-Mainz.de
This study aims at the in situ identification of factors mediating glioma cell invasion requiring adhesion, extracellular matrix degradation, and migration. Forty-five gliomas (astrocytomas, glioblastomas, oligodendrogliomas, and mixed gliomas) were investigated for the immunohistochemical expression of the membrane protein CD44s, the basal lamina proteins laminin, collagen IV, and fibronectin, the lectin galectin-3 recognizing tenascin and N-CAM, as well as for the matrix-degrading enzymes metalloproteinases MMP-2, MMP-9, and cathepsin D. Besides vessels expressing basal lamina proteins, tenascin, MMP-2, MMP-9, and galectin-3, tumor cells revealed strong immunoreactivity for CD44s, tenascin, galectin-3, and N-CAM, which was restricted to solid tumor masses. Single invading cells displayed distinct expression of MMP-2 and MMP-9, also found in solid tumor areas, as well as of cathepsin D. Restricted expression of CD44s, galectin-3, tenascin, and N-CAM in solid tumor masses seems to contribute to homotypical tumor cell adhesion. However, switching to an invasive phenotype, single tumor cells lack this expression pattern and acquire degrading and phagocytic activities by expressing cathepsin D, MMP-2, and MMP-9, which are also expressed by solid tumor masses facilitating the loosening and invasion of single neoplastic cells. The blocking of these factors may be of potential benefit in anti-invasive therapy.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11087057&dopt=Abstract
Am J Physiol Heart Circ Physiol. 2000 Dec;279(6):H2776-85.
Force regulates smooth muscle actin in cardiac fibroblasts.
Wang J, Seth A, McCulloch CA.
Medical Research Council Group in Periodontal Physiology, Faculties of Dentistry and Medicine, University of Toronto, Toronto, Ontario, Canada M5S 3E8.
Chronic ventricular pressure overload can regulate expression of alpha-smooth muscle actin (SMA) in cardiac fibroblasts, but it is unclear if force alone or the concomitant activity of angiotensin II is the principal regulatory factor. To test if SMA mRNA and protein in rat cardiac fibroblasts are regulated directly by force, we first induced SMA expression in cultured cells and then applied magnetically generated perpendicular forces through focal adhesions using collagen-coated magnetite beads. Continuous static forces (0.65 pN/micrometer(2)) selectively reduced SMA but not beta-actin mRNA and protein content within 4 h (to 55 +/- 9% of controls); SMA returned to baseline by 8 h. There was no change in SMA content after force application with either plasma or the cellular fibronectin IIIA domain, BSA, or poly-L-lysine beads. The early loss of SMA was apparently due to selective leakage into the cell culture medium. Treatment with angiotensin II (10 nM) abrogated the force-induced reduction of SMA and increased the levels of this protein. The stress kinase p38 was phosphorylated by force, whereas extracellular signal-regulated kinase 1/2 and c-Jun NH(2)-terminal kinase were unaffected. The p38 kinase inhibitor SB-203580 relieved the force-induced SMA reduction. We conclude that force-induced inhibition of SMA is mediated through the p38 kinase pathway, and this pathway antagonizes angiotensin II regulation of SMA.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11087232&dopt=Abstract
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