Platelet rich fibrin is not a barrier membrane!Or is it?

Platelet-rich fibrin(PRF)is widely used in dentistry and other fields of medicine,and its use has become popular in dental implantology.In several published studies,PRF has been used as a barrier membrane.A barrier membrane is a sheet of a certain material that acts as a biological and mechanical barrier against the invasion of cells that are not involved in bone formation,such as epithelial cells.Among the basic requirements of a'barrier membrane,occlusivity,stiffness,and space maintenance are the criteria that PRF primarily lacks;therefore,it does not fall under the category of barrier membranes.However,there is evidence that PRF membranes are useful in significantly improving wound healing.Does the PRF membrane act as a barrier?Should we think of adding or subtracting some points from the ideal requirements of a barrier membrane,or should we coin a new term or concept for PRF that will incorporate some features of a barrier membrane and be a combination of tissue engineering and biotechnology?This review is aimed at answering the basic question of whether the PRF membrane should be considered a barrier membrane or whether it is something more beyond the boundaries of a barrier membrane.

Systematic evaluation of three porcine-derived collagen membranes for guided bone regeneration

Guided bone regeneration is one of the most common surgical treatment modalities performed when an additional alveolar bone is required to stabilize dental implants in partially and fully edentulous patients.The addition of a barrier membrane prevents non-osteogenic tissue invasion into the bone cavity,which is key to the success of guided bone regeneration.Barrier membranes can be broadly classified as non-resorbable or resorbable.In contrast to non-resorbable membranes,resorbable barrier membranes do not require a second surgical procedure for membrane removal.Commercially available resorbable barrier membranes are either synthetically manufactured or derived from xenogeneic collagen.Although collagen barrier membranes have become increasingly popular amongst clinicians,largely due to their superior handling qualities compared to other commercially available barrier membranes,there have been no studies to date that have compared commercially available porcine-derived collagen membranes with respect to surface topography,collagen fibril structure,physical barrier property,and immunogenic composition.This study evaluated three commercially available non-crosslinked porcine-derived collagen membranes(Striate+TM,Bio-Gide®and CreosTM Xenoprotect).Scanning electron microscopy revealed similar collagen fibril distribution on both the rough and smooth sides of the membranes as well as the similar diameters of collagen fibrils.However,D-periodicity of the fibrillar collagen is significantly different among the membranes,with Striate+TM membrane having the closest D-periodicity to native collagen I.This suggests that there is less deformation of collagen during manufacturing process.All collagen membranes showed superior barrier property evidenced by blocking 0.2–16.4µm beads passing through the membranes.To examine the immunogenic agents in these membranes,we examined the membranes for the presence of DNA and alpha-gal by immunohistochemistry.No alpha-gal or DNA was detected in any membranes.However,using a more sensitive detection method(real-time polymerase chain reaction),a relatively strong DNA signal was detected in Bio-Gide®membrane,but not Striate+TM and CreosTM Xenoprotect membranes.Our study concluded that these membranes are similar but not identical,probably due to the different ages and sources of porcine tissues,as well as different manufacturing processes.We recommend further studies to understand the clinical implications of these findings.

涉及垂直多孔膜的斜向入射波散射问题研究

Oblique surface waves incident on a fixed vertical porous membrane of various geometric configurations is analyzed here.The mixed boundary value problem is modified into easily resolvable problems by using a connection.These problems are reduced to that of solving a couple of integral equations.These integral equations are solved by a one-term or a two-term Galerkin method.The method involves a basis functions consists of simple polynomials multiplied with a suitable weight functions induced by the barrier.Coefficient of reflection and total wave energy are numerically evaluated and analyzed against various wave parameters.Enhanced reflection is found for all the four barrier configurations.

3′-Daidzein sulfonate sodium improves mitochondrial functions after cerebral ischemia/reperfusion injury

3′-Daidzein sulfonate sodium is a new synthetic water-soluble compound derived from daidzein（an active ingredient of the kudzu vine root）. It has been shown to have a protective effect on cerebral ischemia/reperfusion injury in rats. We plan to study the mechanism of its protective effect. 3′-Daidzein sulfonate sodium was injected in rats after cerebral ischemia/reperfusion injury. Results showed that 3′-daidzein sulfonate sodium significantly reduced mitochondrial swelling, significantly elevated the mitochondrial membrane potential, increased mitochondrial superoxide dismutase and glutathione peroxidase activities, and decreased mitochondrial malondialdehyde levels. 3′-Daidzein sulfonate sodium improved the structural integrity of the blood-brain barrier and reduced blood-brain barrier permeability. These findings confirmed that 3′-daidzein sulfonate sodium has a protective effect on mitochondrial functions after cerebral ischemia/reperfusion injury, improves brain energy metabolism, and provides protection against blood-brain barrier damage.