Blur adaptation: clinical and refractive considerations

The human visual system is amenable to a number of adaptive processes; one such process, or collection of processes, is the adaptation to blur. Blur adaptation can be observed as an improvement in vision under degraded conditions, and these changes occur relatively rapidly following exposure to blur. The potential important future directions of this research area and the clinical implications of blur adaptation are discussed.     

Serum ionic fluoride levels in haemodialysis and continuous ambulatory peritoneal dialysis patients

High serum fluoride (F-) in patients with chronic renal failure (CRF) and end-stage renal disease (ESRD) is associated with risk of renal osteodystrophy and other bone changes. This study was done to determine F- in normal healthy controls and patients with ESRD on haemodialysis (HD) or peritoneal dialysis (PD). Seventeen healthy controls (12 males, 5 females) and 39 ESRD patients on dialysis (17 males, 22 females) were recruited in the study in a community with 47.4 +/- 3.28 microM/l (range 44-51 microM/l) of F- content in drinking water. Control subjects showed a mean serum F- concentration of 1.08 +/- 0.350 microM/l. Males in control group showed slightly higher F- levels (1.15 +/- 0.334, range 0.55-1.9 microM/l) than females (0.92 +/- 0.370, range 0.6-1.5 microM/l). Mean serum F- concentration did not correlate significantly with age and sex among control subjects, whereas such correlation was observed in patients with ESRD on dialysis. Mean serum F- concentration was significantly higher in patients on dialysis (2.67 +/- 1.09, range 0.8-5.2 microM/l) than normal controls. When grouped according to sex, the mean serum F- concentration in males (3.05 +/- 1.04, range 1.8-5.2 microM/l) was significantly higher than females (2.38 +/- 1.08, range 0.8-5.2 microM/l). When patients were grouped according to age, it was observed that F- concentration was significantly higher in patients with age groups 21-70 (2.86 +/- 1.05) than those with age group 13-20 years (1.42 +/- 0.531). Thus F- concentration correlated with age and sex, being higher in males and above 20 years. Despite appreciable clearance of F- (39-90%) across the peritoneum, patients on CAPD showed higher serum F- concentration than those on HD (3.1 +/- 1.97 vs 2.5 +/- 1.137 microM/l). Of the total 39 patients on dialysis 39% had their serum F- concentration above 3.0 microM/l, posing the risk of renal osteodystrophy.      

Gentamicin-induced increases in cytosolic calcium in pig kidney cells (LLC-PK1)

LLC-PK1 cells, an established epithelial cell line derived from pig kidney, were tested as a model system for assessing the role of calcium in gentamicin-induced nephrotoxicity. Cell viability was evaluated by a vital dye exclusion procedure, and intracellular free calcium [Ca2+]i was measured employing Fura-2 fluorescence. Exposing cell suspensions (10(6)/ml) to concentrations of the drug, which had no apparent effect on viability, produced a rapid and prolonged increase in intracellular [Ca2+]. The perturbation of calcium homeostasis could be blocked by the addition of mepiperphenidol, an inhibitor of the organic cation transport system. We propose that LLC-PK1 cells are an appropriate model to study drug-induced nephrotoxicity. Gentamicin disrupts calcium homeostasis and causes plasma membrane alterations. Since mepiperphenidol blocked the gentamicin-induced Ca2+ increases, the data suggest that aminoglycosides enter the cell via the organic cation transporter.     

Physiotherapy rehabilitation of the smile after long-term facial nerve palsy using video self-modeling and implementation intentions.

OBJECTIVE: To improve smiling after long-term facial nerve palsy (FNP). Physiotherapy rehabilitation of an adapted (more symmetrical) smile was investigated in FNP subjects 1 year post-onset, using video self-modeling (video replay of only best adapted smiles) and implementation intentions (preplanning adapted smiles for specific situations). STUDY DESIGN AND SETTING: Prospective, blinded clinical trial. Facial-Nerve-Palsy Clinic. RESULTS: After video self-modeling: 1) reaction time (RT) to initiation of adapted smiles became 224 ms faster whereas RT for everyday (asymmetrical) smiles became 153 ms slower; 2) adapted smiles were completed 544 ms faster; 3) adapted smiles had higher overall quality, movement control, and symmetry ratings; and 4) Facial Disability Index scores also improved. Implementation intentions after video self-modeling ensured transfer of adapted smile to everyday situations. CONCLUSION: Following intervention the smile improved, with significant changes in availability, execution speed, and quality. SIGNIFICANCE: This study supports these rehabilitation techniques to maximize quality of smiling following FNP. EBM rating: B-2b.