Role of Thermo-responsiveness and Poly(ethylene glycol) Diacrylate Cross-link Density on Protein Release from Poly(N-isopropylacrylamide) Hydrogels.

Thermo-responsive hydrogels have shown promise as injectable materials for local drug delivery. However, the phase-induced changes in polymer properties of N-isopropylacrylamide (NIPAAm) can pose additional challenges for achieving controlled protein release. In this work, thermo-responsive hydrogels derived from NIPAAm and cross-linked with poly(ethylene glycol) diacrylate (PEG-DA) were synthesized via free radical polymerization.

Effects of inhibition of neuronal nitric oxide synthase on basal retinal blood flow regulation.

Nitric oxide (NO) has been observed to regulate blood flow under basal and stimulated conditions in the retina. Recent evidence suggests that NO produced by neuronal nitric oxide synthase (nNOS) may regulate blood flow in addition to that produced by endothelial nitric oxide synthase (eNOS). The objective of the current study was to investigate the contribution of NO produced by nNOS in the regulation of basal retinal blood flow.

Thermoresponsive hydrogels as a new ocular drug delivery platform to the posterior segment of the eye.

Purpose: To characterize thermoresponsive hydrogels (liquids at room temperature, gels at body temperature) as a novel drug delivery platform to the posterior segment.

Methods: Thermoresponsive hydrogels were synthesized using poly(N-isopropylacrylamide) (PNIPAAm), cross-linked with poly(ethylene glycol) diacrylate (PEG-DA). Proteins were then encapsulated into the hydrogels, including bovine serum albumin (BSA), immunoglobulin G (IgG), and, finally, bevacizumab and ranibiumab.

Preservation of intact adult rat photoreceptors in vitro: study of dissociation techniques and the effect of light.

Purpose: Intact adult photoreceptors in culture can be a valuable tool in the search of therapies for retinal degenerations. The major challenge in this technique is that photoreceptors undergo an alteration in cytoarchitecture and loss of outer segment during the cell culture process. This study compared techniques for the isolation of photoreceptor cells from adult rat retinas to determine which technique yields the highest percent of structurally well preserved cells in vitro.

Suppressors of cytokine-signaling proteins induce insulin resistance in the retina and promote survival of retinal cells.

Objective: Suppressors of cytokine signaling (SOCS) are implicated in the etiology of diabetes, obesity, and metabolic syndrome. Here, we show that some SOCS members are induced, while others are constitutively expressed, in retina and examine whether persistent elevation of SOCS levels in retina by chronic inflammation or cellular stress predisposes to developing insulin resistance in retina, a condition implicated in diabetic retinopathy.

Research Design And Methods: SOCS-mediated insulin resistance and neuroprotection in retina were investigated in 1) an experimental uveitis model, 2) SOCS1 transgenic rats, 3) insulin-deficient diabetic rats, 4) retinal cells depleted of SOCS6 or overexpressing SOCS1/SOCS3, and 5) oxidative stress and light-induced retinal degeneration models.

Scanning laser ophthalmoscope-particle tracking method to assess blood velocity during hypoxia and hyperoxia.

The main objective was to evaluate a Scanning Laser Ophthalmoscope (SLO) based particle tracking method as a means of quantitative assessment of retinal blood velocity and vessel diameter changes in response to hypoxia and hyperoxia. Retinal blood velocities were measured by tracking fluorescent microspheres (1.0 microm diameter) in anesthetized adult pigmented rats.

Test of the paired-flash electroretinographic method in mice lacking b-waves.

Previous studies of rod photoreceptors in vivo have employed a paired-flash electroretinographic (ERG) technique to determine rod response properties. To test whether absence versus presence of the ERG b-wave affects the photoreceptor response derived by the paired-flash method, we examined paired-flash-derived responses obtained from nob mice, a mutant strain with a defect in signal transduction between photoreceptors and ON bipolar cells that causes a lack of the b-wave. Normal littermates of the nob mice served as controls.

Retinal oxygenation and oxygen metabolism in Abyssinian cats with a hereditary retinal degeneration.

Purpose: To investigate the effects of a hereditary retinal degeneration on retinal oxygenation and determine whether it is responsible for the severe attenuation of retinal circulation in hereditary photoreceptor degenerations.

Methods: Seven adult Abyssinian cats affected by hereditary retinal degeneration were studied. Oxygen microelectrodes were used to collect spatial profiles of retinal oxygenation in anesthetized animals.

The electroretinogram components in Abyssinian cats with hereditary retinal degeneration.

Purpose: To examine phototransduction using the a-wave and other aspects of retinal function with the intraretinal b- and c-waves at different stages of an inherited photoreceptor degeneration in Abyssinian cats.

Methods: Vitreal and intraretinal ERGs were recorded from eight dark-adapted, anesthetized Abyssinian cats. Brief bright flashes were used to elicit vitreal a- and b-waves.

Dark adaptation of rod photoreceptors in normal subjects, and in patients with Stargardt disease and an ABCA4 mutation.

Purpose: Psychophysical and electroretinographic (ERG) studies indicate that patients with Stargardt disease exhibit abnormally slow rod dark adaptation after illumination that bleaches a substantial fraction of rhodopsin. However, relatively little information is available concerning rod recovery in this disease after weaker adapting (i.e.

Excitation and desensitization of mouse rod photoreceptors in vivo following bright adapting light.

Electroretinographic (ERG) methods were used to determine response properties of mouse rod photoreceptors in vivo following adapting illumination that produced a significant extent of rhodopsin bleaching. Bleaching levels prevailing at approximately 10 min and approximately 20 min after the adapting exposure were on average 14 % and 9 %, respectively, based on the analysis of visual cycle retinoids in the eye tissues. Recovery of the rod response to the adapting light was monitored by analysing the ERG a-wave response to a bright probe flash presented at varying times during dark adaptation.