Inner Wall Research Articles

Effects of variable permeability on aqueous humor outflow

All previous efforts to quantify the aqueous humor (AH) outflow resistance in the juxtacanalicular tissue (JCT) of the human eye have attempted to treat the tissue as a homogeneous porous material. In this study, we treat the JCT as a heterogeneous tissue with variable permeability. The variable permeability of each sub-region of the JCT is estimated from Quick-Freeze/Deep-Etch images using Karmen–Kozeny theory. Finite element simulations of the fluid flow using Darcy’s law are computed at a micron resolution using a parallel algebraic multigrid (AMG) algorithm. Analyzing strictly the JCT, the overall resistance of this tissue is increased by 35–68% when assuming variable permeability instead of a homogenous tissue. Further, the resistance increase associated with the inclusion of the IW is 2–5 fold greater with a heterogeneous tissue compared to a homogeneous tissue. Because cellular and extracellular structures become denser proximal to the inner wall (IW) endothelium, resistance to AH outflow in this region of the JCT and funneling effects created by pores of the IW become amplified. Overall, the resistance of the JCT/IW domain is under-predicted when treating the JCT as a homogeneous tissue.

Mechanical indentation as a tool for functional characterisation of gene therapy constructs

All previous efforts to quantify the aqueous humor (AH) outflow resistance in the juxtacanalicular tissue (JCT) of the human eye have attempted to treat the tissue as a homogeneous porous material. In this study, we treat the JCT as a heterogeneous tissue with variable permeability. The variable permeability of each sub-region of the JCT is estimated from Quick-Freeze/Deep-Etch images using Karmen–Kozeny theory. Finite element simulations of the fluid flow using Darcy’s law are computed at a micron resolution using a parallel algebraic multigrid (AMG) algorithm. Analyzing strictly the JCT, the overall resistance of this tissue is increased by 35–68% when assuming variable permeability instead of a homogenous tissue. Further, the resistance increase associated with the inclusion of the IW is 2–5 fold greater with a heterogeneous tissue compared to a homogeneous tissue. Because cellular and extracellular structures become denser proximal to the inner wall (IW) endothelium, resistance to AH outflow in this region of the JCT and funneling effects created by pores of the IW become amplified. Overall, the resistance of the JCT/IW domain is under-predicted when treating the JCT as a homogeneous tissue.

Latrunculin B effects on trabecular meshwork and corneal endothelial morphology in monkeys

To determine the mechanism of latrunculin B (LAT-B)-induced decrease in outflow resistance and the effect of LAT-B on the cornea, structural changes of the trabecular meshwork (TM) and the corneal endothelium following LAT-B were studied in the live monkey eye. LAT-B (0.5 μM) and vehicle were administered by anterior chamber exchange and infusion with cationized and non-cationized gold solution in opposite eyes. The eyes were fixed by infusing Ito's solution and enucleated. Anterior segments were quadrisected and embedded in Epon-Embed 812. Morphology of the TM and the corneal endothelium was studied by light and electron microscopy. LAT-B-induced morphological changes in the TM included: (1) loss of microfilament integrity in cells, especially in TM cells on the collagen beams; (2) development of numerous cytoplasmic projections of the sub-canalicular cells (SUB); (3) reorganization of intermediate filaments in Schlemm's canal inner wall (IW) cells; (4) massive ‘ballooning’ of the juxtacanalicular (JXT) region, leading to a substantial expansion of the space between the IW of Schlemm's canal and the trabecular collagen beams; and (5) retention of extracellular matrix (ECM), trapped between the SUB cell layer and IW cells. No detrimental effects on tight junctions, giant vacuoles, and cell–cell and cell–ECM adhesions were observed. Endocytosis of gold particles was not affected. Morphology of the corneal endothelium of the LAT-B-treated eye was unchanged. In conclusion, TM changes in the LAT-B-treated eye suggest that the expansion of the JXT space may account for the decrease in outflow resistance induced by latrunculins. The outflow-effective concentration of LAT-B administered intracamerally does not significantly affect the corneal endothelium.

Functional and structural reversibility of H-7 effects on the conventional aqueous outflow pathway in monkeys

To determine the mechanism of H-7-induced outflow resistance decrease, the reversibility of H-7 effects on outflow pathway was studied physiologically and morphologically in live monkey eyes. Total outflow facility was measured by two-level constant pressure perfusion before (baseline measurement) and after (post-drug measurement) anterior chamber (AC) exchange with 300 μ m H-7 or vehicle in opposite eyes of eight monkeys. H-7 was then removed by AC exchange with drug-free vehicle in both eyes, followed by a 2·5 hr waiting period, after which outflow facility was measured again with (Group 2; n=4) or without (Group 1; n=4) another preceding drug-free AC exchange. For morphological study, five monkeys were initially perfused similarly to Group 1 in physiology, but the facility measurement beginning 2·5 hr after drug removal was either omitted or replaced by gold solution infusion. Following baseline measurement, two of the five monkeys received H-7 or vehicle in opposite eyes, while three monkeys received H-7 in both eyes 2·5 hr apart, contributing one H-7-treated ‘recovery’ eye and one H-7-treated ‘acute’ eye. After perfusion, both eyes of all five monkeys were studied by light and electron microscopy. Outflow facility during post-drug measurement in the H-7-treated eye was significantly increased by two-fold. However, the facility increase was reduced when measured beginning 2·5 hr after drug removal, with the reduction being greater in Group 1. ‘Recovered’ outflow facility after drug removal gradually increased again under continuous AC infusion with drug-free vehicle. Morphologically, major changes in and around Schlemm's canal (SC) in the H-7-treated ‘acute’ eye included protrusion of the entire inner wall (IW) into SC, relaxation of the IW cells and reorganization of the IW cytoskeleton. The changes in IW cells and juxtacanalicular region of the H-7-treated ‘recovery’ eye were non-uniform, with areas resembling the vehicle-treated eye (‘contracted areas’) and areas resembling the H-7-treated ‘acute’ eye (‘relaxed areas’). The average junction-to-junction distances in the IW cells of the H-7-treated ‘recovery’ eye were intermediate between the vehicle-treated eye and the H-7-treated ‘acute’ eye. In conclusion, H-7’s effect on outflow facility seems reversible, but AC exchange or continuous infusion with drug-free vehicle can re-elevate the ‘recovered’ outflow facility. Major morphological changes in the TM immediately after H-7 include IW protrusion, cellular relaxation and cytoskeleton reorganization. The decrease in ‘relaxed areas’ in the TM, in conjunction with the reversed outflow facility, 2·5 hr after drug removal suggests that cellular relaxation in the TM is the structural basis for H-7-induced increase in outflow facility.

エアレータの圧力損失について

Pressure drop in the aerator included in an air-lift cyclone flotation system is balanced with static head pressure, friction loss in the feed pipe and the air-lift pipe, static pressure in the air-lift pipe and pressure drop in the separator.Some experiments were conducted and the results were submitted to dimensional analysis. It was found from this analysis that the flow coefficient ξiincluding inlet velocity and pressure drop terms was a function of dimensionless terms, dc/di, do/dcand the generalized Reynolds number RetIn this relationship Rethad negligible effect in the practicalrange of cyclone flotation on the flow coefficient.Accordingto this analysis, it was also found that the aerator of involute (IV) type was more advantageous than that of innerwall (IW) typein various aspects.