Creation of hydrophilic nitric oxide releasing polymers via plasma surface modification.

Herein, we describe the surface modification of an S-nitrosated polymer derivative via H2O plasma treatment, resulting in polymer coatings that maintained their nitric oxide (NO) releasing capabilities, but exhibited dramatic changes in surface wettability. The poly(lactic-co-glycolic acid)-based hydrophobic polymer was nitrosated to achieve a material capable of releasing the therapeutic agent NO. The NO-loaded films were subjected to low-temperature H2O plasma treatments, where the treatment power (20-50 W) and time (1-5 min) were varied. The plasma treated polymer films were superhydrophilic (water droplet spread completely in <100 ms), yet retained 90% of their initial S-nitrosothiol content. Under thermal conditions, NO release profiles were identical to controls. Under buffer soak conditions, the NO release profile was slightly lowered for the plasma-treated materials; however, they still result in physiologically relevant NO fluxes. XPS, SEM-EDS, and ATR-IR characterization suggests the plasma treatment resulted in polymer rearrangement and implantation of hydroxyl and carbonyl functional groups. Plasma treated samples maintained both hydrophilic surface properties and NO release profiles after storage at -18 °C for at least 10 days, demonstrating the surface modification and NO release capabilities are stable over time. The ability to tune polymer surface properties while maintaining bulk properties and NO release properties, and the stability of those properties under refrigerated conditions, represents a unique approach toward creating enhanced therapeutic biopolymers.

The relationship between central corneal thickness and the optic disc in an elderly population: the Bridlington Eye Assessment Project.

PURPOSE: To determine population-based normative CCT data for elderly white subjects, with and without diabetes, and to explore the relationship between CCT and IOP and HRT2 measurements in such subjects with normal visual fields. METHODS: All eligible subjects were consecutive in a population screened for eye disease. CCT was measured by ultrasound pachymetry, and the optic disc was morphometrically defined using Heidelberg retinal tomography (HRT2). Inclusion criteria were: (1) normal visual field on suprathreshold testing and (2) corrected logMAR acuity of at least 0.3 in both eyes. Subjects with significant corneal pathology, previous corneal surgery, or known history of glaucoma or treatment for raised intraocular pressure were excluded. One eye was randomly selected from each subject for analysis. RESULTS: In all, 983 eyes of 983 subjects were included with 690 HRT images deemed acceptable for the analysis. The mean age (414 men and 569 women) was 73.3 years (minimum 65 years). Mean (SD) CCT was 544.1 (36.5) microm, with a normally distributed range of 429-633 microm. There was no significant difference in CCT between men and women (mean CCT 546.1 and 542.7 microm, respectively, P=0.15, Student's t-test), though CCT was correlated weakly and negatively with age (Pearson's r=-0.063, P=0.047). Diabetic patients (n=103) had a greater mean CCT than non-diabetic patients (551.9 and 543.0 microm respectively, P=0.02). No significant correlation was found between any global optic disc parameter and CCT in the 690 eyes analysed. CONCLUSION: Elderly white eyes with normal fields have CCTs that are normally distributed, with those from diabetic persons having greater CCTs. No clear evidence of a relationship between CCT and HRT2 optic disc parameters used in glaucoma diagnosis was found.

Detecting glaucoma with RADAAR: the Bridlington Eye Assessment Project.

AIMS: To develop a diagnostic algorithm using rim/disc area asymmetry ratio (RADAAR) to discriminate between normal and glaucomatous eyes using the Heidelberg retina tomograph (HRT). METHODS: RADAAR was calculated by dividing rim/disc area ratio of the larger disc by that of the smaller disc. RADAAR normal tolerances in each disc sector were generated using 611 population based normal elderly individuals (mean age 72.5 years). Overall status for each individual was equal to the worst disc sector. Sensitivity was assessed in 45 patients with open angle glaucoma. RESULTS: RADAAR variance was significantly greater in glaucoma compared with normality in all disc sectors (p<0.001). Normal RADAAR limits were not dependent on age or sex. Overall, at the 99th percentile limit, the diagnostic algorithm's specificity was 95.1% with a sensitivity of 55.6%. Males with glaucoma showed greater RADAAR variance than females. Corresponding sensitivity of the diagnostic algorithm was 63.0% and 44.4% in males and females respectively, although this difference was not statistically significant (p = 0.43). CONCLUSION: The RADAAR diagnostic algorithm detected glaucoma with moderate sensitivity but was limited by significant numbers of glaucoma patients with symmetrical optic disc changes. RADAAR may have greater sensitivity in males than in females although this requires confirmation in further studies.

The effect of stimulation frequency on blood flow in rat fast skeletal muscles.

The effect of stimulation frequency on intact muscle blood flow was measured by radiolabelled microsphere entrapment. Maximum flow occurred at 4 Hz in both extensor digitorum longus and tibialis anterior (156 +/- 13 and 205 +/- 24 ml min-1 (100 g)-1, respectively). Regional differences in fibre composition were reflected in the relative flow rates, with functional hyperaemia in the oxidative tibialis anterior core being twice that of the glycolytic cortex at 10 Hz. A consistent difference in flow between legs was noted that may originate from an unequal division of the common iliac artery in rats.