Polyvinyl alcohol/cellulose hydrogel as possible corneal stroma substitute in drug permeation tests

The permeation studies of active compounds and formulations are necessary to verify the capability of molecules to pass through the physiological barrier of our body. In order to develop a 3D model of the cornea, preparation and characterization of different hydrogels as corneal stroma substitutes were tested.

Tissue-engineered blood-brain barrier models via directed differentiation of human induced pluripotent stem cells

Three-dimensional (3D) tissue-engineered models of the blood-brain barrier (BBB) recapitulate in vivo shear stress, cylindrical geometry, and cell-ECM interactions. Here we address four issues associated with BBB models: cell source, barrier function, cryopreservation, and matrix stiffness. We reproduce a directed differentiation of brain microvascular endothelial cells (dhBMECs) from two fluorescently labeled human induced pluripotent stem cell lines (hiPSCs) and demonstrate physiological permeability of Lucifer yellow over six days. Microvessels formed from cryopreserved dhBMECs show expression of BBB markers and maintain physiological barrier function comparable to non-cryopreserved cells. Microvessels displaying physiological barrier function are formed in collagen I hydrogels with stiffness matching that of human brain. The dilation response of microvessels was linear with increasing transmural pressure and was dependent on matrix stiffness. Together these results advance capabilities for tissue-engineered BBB models.

Effects of Mycotoxins on the Intestine

The gastrointestinal tract is the first physiological barrier against food contaminants, as well as the first target for these toxicants [...]

A Systematic Review of Security in Electronic Commerce- Threats and Frameworks

There is a remarkable scope for more streamlined living through an increase of e-platforms specially ecommerce, but this coincides with an increase in security concerns since the global market place is virtual and anonymous. Therefore, users have to blindly trust the online providers. In order to overcome this physiological barrier the eplatforms should ensure utmost security. If not the ecommerce industry is unableto perform in the market effectively. Thereby arises the need to perform a systematic review of security issues in the e-commerce industry and to discover how different frameworks address these problems. This paper aims to identifythe main security problems faced by both customers and vendors when interacting with ecommerce platforms and to evaluate general security management frameworks based on the main security areas identified.

A switchable NO-releasing nanomedicine for enhanced cancer therapy and inhibition of metastasis

Clinical chemotherapy for cancer is limited by the physiological barrier of tumors, resulting in low drug delivery to tumors, poor efficacy of drugs and inability to block tumor metastasis.

The expression of Fas ligand on normal and stabbed-disc cells in a rabbit model of intervertebral disc degeneration: a possible pathogenesis

Object The nucleus pulposus has been reported to be an immunologically privileged site. The expression of Fas ligand (FasL) on normal and herniated lumbar disc cells has been reported. The relationship between a physiological barrier and the role of FasL has not yet been addressed. To clarify this relationship and to investigate a possible pathogenesis of intervertebral disc degeneration (IDD), the expression of Fas and FasL (a mean apoptosis index) on normal and stabbed-disc cells was examined in a rabbit model of IDD. Methods Using defined needle gauges and depths, the anular puncture model of IDD was established in rabbits. The normal and stabbed discs were harvested at 3, 6, and 10 weeks after surgery. Immunohistochemical staining of these discs for Fas and FasL was performed using standard procedures. The mean apoptosis indices of the disc cells were determined using flow cytometry analysis. The nucleus pulposus cells from the normal discs exhibited relatively weak immunopositivity, whereas the nucleus pulposus cells from the stabbed discs exhibited strong immunopositivity. There was a significant difference (p < 0.001) in the percentage of FasL-positive nucleus pulposus cells between the normal discs and the stabbed discs. The mean apoptosis indices of the stabbed-disc cells at 3, 6, and 10 weeks poststab were significantly higher than those in normal disc cells (p < 0.001, 0.002, and 0.006, respectively). There was a significant correlation between the degree of FasL-positive expression and the degree of Fas-positive expression of the nucleus pulposus cells poststab (r = 0.571, p = 0.0036). Conclusions These observations indicate that the nucleus pulposus is an immunologically privileged site. This immunological privilege is maintained by FasL and the physiological barrier together. When the physiological barrier was damaged (by stabbing the disc), the role of FasL changed, and FasL was coexpressed with Fas to induce apoptosis of disc cells. These results indicate that an autoimmune reaction may be a possible pathogenesis of IDD.