900 research outputs found
Preloaded Tissues for Descemet Membrane Endothelial Keratoplasty
No full textIntroduction To determine the feasibility of preloading endothelial tissues for Descemet membrane endothelial keratoplasty (DMEK). Design Laboratory investigation. Methods setting: Institutional. participants: Twenty human donor corneas unsuitable for transplantation with endothelial cell density in a range of 1600-2700 cells/mm2. Intervention: The endothelium was punched, stripped (8.5 mm diameter) and manually tri-folded with the endothelial side inward. The excised membranes were gently moved in a 2.2 intraocular lens (IOL) cartridge and pulled further in the funnel using 25 G end-grasping forceps. The cartridge was filled with transport media (TM) (sealed at its funnel and back entrance with a stopper) and the tissue was preserved for 4 days at room temperature in the bottles containing TM. main outcome measures: Success rate of preparation, processing time, endothelial cell loss (ECL), and active metabolism. Results The tissues were peeled and loaded successfully in all cases. Average stripping and loading time was 20 and 4.5 minutes, respectively. ECL after preservation was 4.35% with 3.55% (± 5.89%) mortality and 7.80% (± 14.12%) uncovered areas. A total of 0.55 (± 0.26) mg/mL of glucose was consumed by the cells showing active metabolism. Conclusions Tri-folded (endothelium-in) DMEK grafts can be preloaded using TM in an IOL cartridge and stored up to 4 days with limited endothelial damage. Direct injection of TM should be avoided because of the presence of bovine serum, but the tissue can be washed using balanced salt solution and gently injected. Alternatively, the graft can be easily delivered using a bimanual pull-through technique. Preloading DMEK grafts will simplify the surgery with reproducibility, reduced surgical time, and reduced tissue wastage, cost, and logistical requirements
Interference of an alfa component in immunological determinations of pregnancy specific ß 1-glycoprotein in serum
No full textNumerical studies to detect chaotic motion in the full planar averaged three-body problem
No full textIn this paper, the author deals with a well-known problem of Celestial Mechanics, namely the three-body problem. A numerical analysis has been done in order to prove existence of chaotic motions of the full-averaged problem in particular configurations. Full because all the three bodies have non-negligible masses and averaged because the Hamiltonian describing the system has been averaged with respect to a fast angle. A reduction of degrees of freedom and of the phase-space is performed in order to apply the notion of covering relations and symbolic dynamics
Banking of donor tissues for descemet stripping automated endothelial keratoplasty
No full textPURPOSE: The demands for precut lamellar grafts for Descemet stripping automated endothelial keratoplasty rose in our eye bank from 74 in 2007 to 408 in 2010. To meet this expanding requirement, we explored the possibility to preserve these preparations in organ culture. METHODS: Organ cultured corneas, stored in a medium containing 6% dextran, were mounted on a Moria artificial anterior chamber, deprived of the epithelium and then cut with a microkeratome. The posterior lamella was protected by positioning the anterior stromal cap, trephined at a diameter of 8.5 mm and stored at 31°C in the medium containing dextran. The endothelium was examined with trypan blue and alizarin staining and tested for its glycolytic activity (conversion of glucose into lactate). RESULTS: Incubation for a period of 1 week caused a small increase in the cell loss observed after trephination (from 6.2% to 10.6%). After 2 weeks, the decrease in endothelial cell density was 19.9% but the endothelial organization remained intact. The rate of glycolysis remained unchanged during the 2 weeks of preservation, with the majority of glucose uptake accounted for by lactate production. The thickness of the lenticules remained constant, ranging from 170 to 180 Î1⁄4m during the preservation. CONCLUSIONS: The lamellar grafts for Descemet stripping automated endothelial keratoplasty may be stored in organ culture for 2 weeks without damaging the endothelium or increasing the overall thickness. Copyright © 2012 by Lippincott Williams & Wilkins
Sensing inhomogeneous mechanical properties of human corneal Descemet's membrane with AFM nano-indentation
No full textThe paper describes a highly space-resolved characterization of the surface mechanical properties of the posterior human corneal layer (Descemet's membrane). This has been accomplished with Atomic Force Microscopy (AFM) nano-indentation by using a probe with a sharp tip geometry. Results indicate that the contact with this biological tissue in liquid occurs with no (or very low) adhesion. More importantly, under the same operating conditions, a broad distribution of penetration depth can be measured on different x-y positions of the tissue surface, indicating a high inhomogeneity of surface stiffness, not yet clearly reported in the literature. An important contribution to such inhomogeneity should be ascribed to the discontinuous nature of the collagen/proteoglycans fibers matrix tissue, as can be imaged by AFM when the tissue is semi-dry. Using classical contact mechanics calculations adapted to the specific geometry of the tetrahedral tip it has been found that the elastic modulus E of the material in the very proximity of the surface ranges from 0.23 to 2.6 kPa
Descemet membrane endothelial keratoplasty tissue preparation from donor corneas using a standardized submerged hydro-separation method
No full textPurpose To standardize a novel submerged hydro-separation technique for Descemet membrane endothelial keratoplasty (DMEK) graft preparation from donor corneal tissues. Design Experimental study, laboratory investigation. Methods setting: The Veneto Eye Bank Foundation, Venice, Italy. study population: Fifty-four random human donor corneal tissues unsuitable for transplantation. intervention: Donor corneas were laid in a sterile basin partially filled with tissue culture medium. A 25 gauge needle with 1 mL mounted syringe was filled with the tissue culture medium. The needle (with bevel up) was bent to 90 degrees and was inserted in the posterior cornea initiating beneath the trabecular meshwork. It was further advanced toward the midperiphery, ensuring that only the bevel was inserted, considering it as a threshold of insertion. The liquid was injected with a medium to high pressure into the posterior stroma or in the Descemet membrane-stroma interface to create the bubble. The tissues were preserved for 7 days in tissue culture medium at 31°C. Parametrical, physiological and histological analyses were carried out. main outcome measures: Larger-diameter tissue, no tissue wastage, reproducibility, and preshipment evaluation. Results Complete detachment was achieved in all the cases without any tissue wastage. Average diameter of the excised graft was 10.80 (±0.28) mm and endothelial cell loss post preservation was 11.48%. Expression of tight junction protein and regular morphology was observed post preservation. No signs of cell apoptosis were seen. Histological analysis showed elimination of residual stroma in most of the cases. Conclusions The submerged hydro-separation method reduces tissue wastage. It allows preshipment evaluation, thus allowing a validated tissue to be transported from the eye banks to the surgeon. Because of the liquid interface, the peeling of the DMEK graft becomes easy for transplantation. © 2014 by Elsevier Inc. All rights reserved
Distribution of SP1, immunoreactivity among different plasma proteins: real molecular heterogeneity or adsorption of SP1-beta to other plasma proteins?
No full textInterference of an alpha-2 component in immunological determinations of pregnancy-specific beta-1 glycoprotein in serum
No full textPregnancy-specific beta 1 glycoprotein (SP1-beta) was purified from human retroplacental blood by sequential anion exchange chromatography, gel chromatography and affinity chromatography. The final preparation appeared to be electrophoretically and immunochemically pure and was in particular free from any component with alpha mobility. The preparation was used as immunogen in rabbits as well as tracer and standard for radioimmunoassay and for cross- and rocket-immunoelectrophoresis. It was shown that this radioimmunoassay procedure allowed quantitative determination of SP1-beta glycoprotein without interference by the alpha component
Banking of Donor Tissues for Descemet Stripping Automated Endothelial Keratoplasty.
No full textPurpose: The demands for precut lamellar grafts for Descemet stripping automated endothelial keratoplasty rose in our eye bank from 74 in 2007 to 408 in 2010. To meet this expanding requirement, we explored the possibility to preserve these preparations in organ culture.
Methods: Organ cultured corneas, stored in a medium containing 6% dextran, were mounted on a Moria artificial anterior chamber, deprived of the epithelium and then cut with a microkeratome. The posterior lamella was protected by positioning the anterior stromal cap, trephined at a diameter of 8.5 mm and stored at 31[degrees]C in the medium containing dextran. The endothelium was examined with trypan blue and alizarin staining and tested for its glycolytic activity (conversion of glucose into lactate).
Results: Incubation for a period of 1 week caused a small increase in the cell loss observed after trephination (from 6.2% to 10.6%). After 2 weeks, the decrease in endothelial cell density was 19.9% but the endothelial organization remained intact. The rate of glycolysis remained unchanged during the 2 weeks of preservation, with the majority of glucose uptake accounted for by lactate production. The thickness of the lenticules remained constant, ranging from 170 to 180 [mu]m during the preservation.
Conclusions: The lamellar grafts for Descemet stripping automated endothelial keratoplasty may be stored in organ culture for 2 weeks without damaging the endothelium or increasing the overall thickness
Design, Testing, Construction and Verification of a Condenser Radiator for a Two Phase Cooling System for Space Application
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