Austen El-Osta

In vitro model for the study of human posterior capsule opacification.

Purpose: To develop and evaluate a model for the organ culture of human lens capsules that reduces problems inherent in preexisting models for the study of in vitro posterior capsule opacification (PCO). Methods: Human lenses (N = 110) were isolated from donor eyes and supported externally within a lens holder system by medical‐grade cyanoacrylate glue, allowing visualization of the entire capsular bag. After capsulorhexis and lens extraction were performed, the capsule specimens were maintained at physiological conditions for up to 4 weeks. The area of lens epithelial cell (LEC) coverage over the posterior capsule surface was determined objectively on a daily basis using a graticule. Lens epithelial cell behavior was correlated with clinical data and other in vitro PCO models. Results: Cyanoacrylate glue did not appear to be toxic to LECs at the concentration used. The amount of viable epithelium after nuclear extraction was dependent on the age and postmortem time of the specimen. Viable LEC cultures were obtained from eyes up to 9 days postmortem. The time from death to culture or from enucleation to culture did not influence LEC viability if it was fewer than 5 days. The LEC proliferation rates and confluence times were age dependent and correlated closely between pairs of eyes. Conclusions: Results show that the lens holder model is a more physiological method for supporting the capsule and is a robust, reproducible system for the study of LEC migration and proliferation. It allows visualization within the entire capsular bag. Intraocular lenses can be implanted in this system in a way that more closely resembles the in vivo scenario. This model can be used to evaluate therapeutic measures to prevent PCO.

Scleral hydraulic conductivity and macromolecular diffusion in patients with uveal effusion syndrome

PURPOSE To determine whether uveal effusion syndrome (UES) is caused by altered scleral permeability to water and large molecules. METHODS Transscleral water movement was measured using surgically removed sclera clamped in a modified Ussing chamber and connected to a water column set at intraocular pressure. Sclera was also clamped between two hemichambers, and transscleral diffusion of FITC-dextrans (4.4-77 kDa) was measured with a spectrophotometer. Clinical data were prospectively collected using postal questionnaires. RESULTS Ten patients (mean age, 63 years; mean spherical equivalent, +4.7 D) had a median preoperative visual acuity of 0.20 that improved to 0.33 after surgery. Nine eyes showed visual improvement, three worsened, and two were unchanged. Histology showed disorganization of collagen fibrils, with amorphous deposits expanding the interfibrillary spaces. The mean thickness (+/-1 SD) of the excised scleral specimens was 585 +/- 309 microm, and the mean specific hydraulic conductivity was 23.9 +/- 27.5 x 10(-14) cm(2), compared with 5.8 +/- 3.9 x 10(-14) cm(2) in age-matched control specimens (P = 0.068). Three specimens had hydraulic conductivity above the 95% CI of the controls. Control eyes showed a significant reduction in diffusion coefficient (D) with age. Eyes had a mean D of 5.69 +/- 5.35 x 10(-8) cm(2) x s(-1), similar to control eyes (6.14 +/- 2.40 x 10(-8) cm(2) x s(-1), 20 kDa dextran). In one eye, the result was higher than the 95% CI of the control; in three, it was lower. CONCLUSIONS UES is not caused by reduced scleral hydraulic conductivity, which tends to be higher than expected. Reduced macromolecular diffusion may impede the normal transscleral egress of albumin with subsequent osmotic fluid retention in some, but not all eyes.

Increased sequestration of matrix metalloproteinases in ageing human Bruch's membrane: implications for ECM turnover.

PURPOSE The ageing of Bruchs membrane is associated with progressive reduction in the degradation of the capacity for ECM turnover mediated by the matrix metalloproteinase (MMP) system. In this study, the free and bound pools of all gelatinase species were quantified to aid in assessing the likelihood of reduced availability of pro-MMPs for activation in ageing Bruchs membrane. METHODS Bruchs membrane from macular locations (10 eyes; donor age range, 21-84 years) was mounted in Ussing chambers and eluted with phosphate-buffered saline to release the free pool of MMPs. Free and bound pools of MMPs were subjected to gelatin zymography, and individual gelatinase species were quantified by densitometric scans. RESULTS The zymograms displayed six gelatinase species: four corresponding to the pro- and active forms of MMP-2 and -9 and two high-molecular-weight polymeric forms designated HMW1 and -2, corresponding to approximate molecular masses of 195 and 391 kDa, respectively. The ageing of Bruchs membrane was associated with an exponential increase in the percentage of pro-MMPs bound to the membrane (pro-MMP-2: %age bound = 0.54 exp(0.04 x age), r = 0.87, P < 0.01; and pro-MMP-9: %age bound = 5.0 exp(0.03 x age), r = 0.8, P < 0.01). A similar exponential increase was seen in the percentage of bound HMW1 species (%bound = 11.7 exp(0.018 x age; P < 0.05). The HMW2 species was virtually all bound to the membrane, but some release was observed in the very elderly. CONCLUSIONS The ageing of Bruchs membrane was associated with progressive sequestration of MMPs reducing the free concentration and potential for activation. These changes may underlie the reduction in degradation that leads to the age-related increase in the thickness of the membrane.

Towards a strategic alignment of public health and primary care practices at local levels – the case of severe and enduring mental illness

Abstract The rapidly increasing number of people who have long-term conditions requires a system of coordinated support for self-care throughout the NHS. A system to support self-care needs to be aligned to systems that support shared-care and community development, making it easier for the multidisciplinary teams who provide care to also help patients and populations to help themselves. Public health practitioners need to work closely with clinicians to achieve this. The best place to coordinate this partnership is a community-based coordinating hub, or local health community – a geographic area of about 50,000 population where different contributions to self-care can be aligned. A shared vision for both health and disease management is needed to ensure consistent messaging by all. A three tier system of shared care can help to combine vertical and horizontal integration. This paper uses severe and enduring mental illness as an exemplar to anticipate the design of such a system.

Does use of point-of-care testing improve cost-effectiveness of the NHS Health Check programme in the primary care setting? A cost-minimisation analysis

Objective To determine if use of point of care testing (POCT) is less costly than laboratory testing to the National Health Service (NHS) in delivering the NHS Health Check (NHSHC) programme in the primary care setting. Design Observational study and theoretical mathematical model with microcosting approach. Setting We collected data on NHSHC delivered at nine general practices (seven using POCT; two not using POCT). Participants We recruited nine general practices offering NHSHC and a pathology services laboratory in the same area. Methods We conducted mathematical modelling with permutations in the following fields: provider type (healthcare assistant or nurse), type of test performed (total cholesterol with either lab fasting glucose or HbA1c), cost of consumables and variable uptake rates, including rate of non-response to invite letter and rate of missed [did not attend (DNA)] appointments. We calculated total expected cost (TEC) per 100 invites, number of NHSHC conducted per 100 invites and costs for completed NHSHC for laboratory and POCT-based pathways. A univariate and probabilistic sensitivity analysis was conducted to account for uncertainty in the input parameters. Main outcome measures We collected data on cost, volume and type of pathology services performed at seven general practices using POCT and a pathology services laboratory. We collected data on response to the NHSHC invitation letter and DNA rates from two general practices. Results TEC of using POCT to deliver a routine NHSHC is lower than the laboratory-led pathway with savings of £29 per 100 invited patients up the point of cardiovascular disease risk score presentation. Use of POCT can deliver NHSHC in one sitting, whereas the laboratory pathway offers patients several opportunities to DNA appointment. Conclusions TEC of using POCT to deliver an NHSHC in the primary care setting is lower than the laboratory-led pathway. Using POCT minimises DNA rates associated with laboratory testing and enables completion of NHSHC in one sitting.