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.     

Correlation of growth factor receptor expression with clinical growth in vestibular schwannomas.

OBJECTIVE: To examine the relationship between growth rate of vestibular schwannomas and the expression of various growth factor receptors. STUDY DESIGN: Retrospective case review of clinical growth rate in conjunction with a histopathologic and immunohistochemical reexamination of archival specimens. SETTING: A tertiary referral neurotologic center. PATIENTS: Three groups: a historical group to act as controls, consisting of 30 patients with sporadic vestibular schwannomas removed before the unit adopted an initial interval scan policy; a group of 14 patients with sporadic vestibular schwannomas who had undergone an initial interval scan policy, showed radiologic evidence of growth, and therefore had their schwannoma removed; and a group of 16 schwannomas removed from 11 neurofibromatosis Type 2 patients. MAIN OUTCOME MEASURES: A comparison between the three clinical groups using immunohistochemical studies to determine the level of expression of the proliferation factor Ki-67, c-erbB-2, and c-erbB-3 receptors and fibroblastic growth factor receptors 1 and 4. RESULTS: The level of expression of the proliferation factor Ki-67 was very low and similar in all three groups. C-erbB-2 and c-erbB-3 receptors were not expressed in any of the groups. fibroblastic growth factor receptor 4 expression was not significantly different, but there was a variation in the expression of fibroblastic growth factor receptor 1 between the three groups that correlated well with the differing incidence of growth in the groups. The increase in expression of fibroblastic growth factor receptor 1 in the neurofibromatosis Type 2 group was not statistically significant, but the increase in expression of fibroblastic growth factor receptor 1 in the growing sporadic group was statistically significant when compared with the historical controls. The level of fibroblastic growth factor receptor 1 expression correlates significantly with the rate of growth as measured on interval magnetic resonance imaging. CONCLUSIONS: Overexpression of fibroblastic growth factor receptor 1 has a positive correlation with the incidence and the rate of growth of sporadic vestibular schwannomas.     

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.      

Regional Variation and Use of Exception Letters for Cadaveric Liver Allocation in Children with Chronic Liver Disease

The Pediatric End-Stage Liver Disease (PELD) score was designed to reduce subjectivity in liver allocation and to advantage patients with a higher probability of waiting list mortality. The aims of this study were to determine the impact of PELD implementation for children with chronic liver disease and to assess whether PELD met its goal of standardization of liver allocation for children. This study used data reported to the United Network for Organ Sharing (UNOS) registry for children with chronic liver disease receiving primary cadaveric liver transplant between January 2000 and December 2001 (pre-PELD) and March 2002 and July 2003 (PELD). PELD reduced the percentage of children transplanted while in an intensive care unit and as status 1. A calculated PELD score was used for allocation in only 52% of recipients. Thirty percent were status 1 at transplant and PELD scores granted by exception were used for allocation in 18% of patients. There was regional variation in PELD score at allocation and use of exception scores with a significant relationship between PELD score and percentage of exception cases. Regional variation suggests that PELD has not resulted in standardization of listing practices in pediatric liver transplantation.     

Tympanosclerosis—how we look at it

Tympanosclerosis (TS) is a common sequelae of chronic otitis media found in all age groups. Over a period of 3 years, out of 520 surgical cases, 68 (13%) were found to have varying amounts of Tympanosclerotic plaques (TSP) warranting surgical removal. 60% had extension of TSP over the ossicular chain thus affecting its mobility. Deliberate surgical removal of TSP was undertaken for hearing improvement. Systematic and meticulous removal of TSP rather than en-bloc removal has been found to improve the hearing as close to as in, non-tympanosclerotic ear surgery.     

Inhibition of positively rewarding behavior by the heightened aggressive state evoked either by pain-inducing stimulus or septal lesion

Using a footshock elicited aggression paradigm, aggressive responses were scored in normal and in septal-lesioned adult male Wistar rats. Septal lesions were made electrolytically to include the medial and lateral septal nuclei. The lesion was confirmed by behavioral criteria (septal aggression) and post-mortem histology. The aggressive response types (threat, attack) of the septal animals were compared with their corresponding age and weight matched controls. Results showed a statistically significant increase (P = 0.05) in the number of attack responses but not the threat responses in septal animals. The modulatory role of the aggressive experience on responsiveness to positively rewarding or hedonic stimuli was assessed by quantifying the intracranial self-stimulation (SS) rates that were obtained before and after an aggression schedule. For testing the SS behavior bipolar electrodes were implanted in the ventral tegmental area--substantia nigra (VTA-SN). Results showed a decrease in SS pedal press rates in post-aggression schedule as compared to the pre-aggression period in the normal subjects. This depressing effect lasted for over a week. In septal lesioned rats the SS rates were virtually abolished even without having an aggressive schedule. These experiments revealed the effect of environment and of a brain area in provoking aggressive mood and its inhibitory consequence on responding for positive experience.