Changes In Critical Flicker Frequency Research Articles

Lactobacillus paracasei KW3110 Suppresses Inflammatory Stress-Induced Premature Cellular Senescence of Human Retinal Pigment Epithelium Cells and Reduces Ocular Disorders in Healthy Humans.

Lactobacillus paracasei KW3110 (KW3110) has anti-inflammatory effects and mitigates retinal pigment epithelium (RPE) cell damage caused by blue-light exposure. We investigated whether KW3110 suppresses chronic inflammatory stress-induced RPE cell damage by modulating immune cell activity and whether it improves ocular disorders in healthy humans. First, we showed that KW3110 treatment of mouse macrophages (J774A.1) produced significantly higher levels of interleukin-10 as compared with other lactic acid bacterium strains (all p < 0.01). Transferring supernatant from KW3110- and E. coli 0111:B4 strain and adenosine 5′-triphosphate (LPS/ATP)-stimulated J774A.1 cells to human retinal pigment epithelium (ARPE-19) cells suppressed senescence-associated phenotypes, including proliferation arrest, abnormal appearance, cell cycle arrest, and upregulation of cytokines, and also suppressed expression of tight junction molecule claudin-1. A randomized, double-blind, placebo-controlled parallel-group study of healthy subjects (n = 88; 35 to below 50 years) ingesting placebo or KW3110-containing supplements for 8 weeks showed that changes in critical flicker frequency, an indicator of eye fatigue, from the week-0 value were significantly larger in the KW3110 group at weeks 4 (p = 0.040) and 8 (p = 0.036). These results suggest that KW3110 protects ARPE-19 cells against premature senescence and aberrant expression of tight junction molecules caused by chronic inflammatory stress, and may improve chronic eye disorders including eye fatigue.

P: 47 Risk of Recurrent Hepatic Encephalopathy (HE) in Patients With Liver Cirrhosis: A German Registry Study

BACKGROUND: Patients with Hepatic Encephalopathy (HE) show a low quality of life, recurrent hospitalizations and an increased mortality. We aimed to assess the natural course of patients after a recent HE-episode under the conditions of the German health system, as respective data were not available. METHODS: Fifteen sites from Germany - 8 of them liver transplant (LT) centers - took part in an observational prospective study including cirrhotic patients who had been hospitalized due to an acute episode of HE within 3 months before recruitment. Age &lt; 18 years, no liver cirrhosis, malignancies and current hospitalization were exclusion criteria. Demographic and clinical data, health related quality of life (HRQoL) score SF-36, psychometric hepatic encephalopathy score (PHES) and critical flicker frequency (CFF) were assessed and monitored quarterly for one year. Primary endpoint was a novel clinical manifestation of HE necessitating hospital admission. Secondary endpoints were the combined endpoint of hospital admission for a novel HE episode and/or death, the dynamics of the West Haven Criteria (WHC) as well as changes in CFF, PHES and SF-36. RESULTS: A total of 115 patients were recruited. Fourteen patients (12.4 %) died during the study period due to complications of liver cirrhosis other than HE. For 67 subjects follow-up data were available in accordance with the protocol. After a median of 113 days half of the per protocol cohort (N = 34) was re-admitted due to a recurrent manifestation of HE. The patient groups with and without re-hospitalization differed significantly regarding recruitment sites (LT centers vs no LT centers) (P = 0.005), interval from discharge to recruitment (P = 0.007), history of more than 4 HE relapses prior to recruitment (P = 0.029), SF-36 mental score (P = 0.046) and PHES ≤ −3 (P = 0.004), whereas CFF, clinical (e.g. MELD score, WHC grade) and laboratory data did not differ. Of note, CFF performance was correct only in about half of both, the total and the per protocol group. Patients with incorrect CFF performance had worse PHES results than those with valid CFF measurement. Multiple logistic regression analysis revealed a PHES test result of ≤−3 as an independent risk factor for re-hospitalization (P = 0.046). CONCLUSIONS: Mortality in our cohort is comparatively low. Despite advanced treatment strategies, patients with a history of HE are still sincerely jeopardized to develop recurrent clinical HE. The PHES test appears useful for detection, monitoring and stratification of recurrent HE. Patients with PHES ≤−3 at baseline had an increased risk of deterioration.

Diagnostic and prognostic values of critical flicker frequency determination as new diagnostic tool for objective HE evaluation in patients undergoing TIPS implantation

The diagnostic and prognostic value of critical flicker frequency (CFF) analysis for assessment of severity and dynamics of hepatic encephalopathy (HE) was studied before and after implantation of a transjugular intrahepatic portosystemic shunt (TIPS). Sixty-three cirrhotic patients were retrospectively analyzed for the consequences of TIPS implantation. Thirty-one cirrhotic patients without TIPS implantation served as age-matched, sex-matched, Child-Pugh-matched controls. CFF and computer psychometric tests as objective test parameters of HE-severity were evaluated for analysis of visual discrimination ability, general arousal and cognitive function. Kaplan-Meier method and Cox proportional hazards regression model were used for analysis of prognostic significances. In the control group, HE-severity was stable during the observation period (442+/-428 days) with minimal changes in CFF (-0.1+/-1.9 Hz). In the intervention group, TIPS implantation had no effect on HE-severity in 44% of the patients and CFF shifted by only 0.01+/-1.5 Hz. Thirty-five and 21% of the patients experienced an aggravation or improvement of HE after TIPS implantation, respectively. In HE improvers CFF increased by 3.3+/-2.3 Hz and decreased by 3.5+/-1.5 Hz in those experiencing an aggravation of HE-severity. Univariate analysis showed that overall survival in the study population inversely correlated with HE-severity and serum alkaline phosphatase activity and positively correlated with serum sodium, albumin and CFF. Serum albumin, alkaline phosphatase levels and CFF were independent predictors of survival in a multivariate Cox regression analysis. The data show that pre-TIPS HE does not predict post-TIPS encephalopathy. Otherwise, CFF can reliably pick up the evolution of HE-severity after TIPS implantation. Low pre-TIPS CFF is indicative for a poor prognosis and may help to identify transplant candidates without delay.

Deep sedation with propofol does not precipitate hepatic encephalopathy during elective upper endoscopy

The risk of hepatic encephalopathy (HE) precipitated by propofol has not been established. To know whether the use of propofol for endoscopy in patients with cirrhosis induces minimal or overt HE. A cohort study. A tertiary-referral university hospital endoscopy unit. Patients with cirrhosis who received an endoscopy with propofol sedation. We excluded patients with clinical HE. A group of patients without liver disease was included to compare the incidence of adverse effects. Minimal HE (MHE) was diagnosed by using the psychometric hepatic encephalopathy score (PHES) battery of psychometric tests. Cognitive status before and 1 hour after the endoscopy was evaluated by measuring the critical flicker frequency (CFF). Overt and minimal HE. Twenty patients with cirrhosis and 20 patients without cirrhosis were included. There were no differences between groups in the incidence of adverse effects. Thirteen patients (65%) had MHE before the endoscopy. No patient developed overt HE after sedation. We did not observe differences in CFF before and after sedation in patients without MHE: median (25th-75th percentile), 40.8 Hz (37.1-46.0 Hz) versus 41.1 Hz (36.0-44.3 Hz), P = .8). None of the patients who were without MHE showed a decrease in the CFF under the cutoff of 39 Hz after sedation. There were not significant changes in CFF before and after propofol sedation in patients previously diagnosed of MHE: median (25th-75th percentile), 40.6 Hz (36.8-49.1 Hz) versus 42.7 Hz (36.8-52.4 Hz), P = .08. A small number of patients were included in the study. The use of propofol in the sedation of patients with cirrhosis during endoscopic procedures does not precipitate minimal or overt HE.

Analysis of visual modulation sensitivity. III. Meridional variations in peripheral flicker sensitivity.

Critical flicker frequency (CFF) and modulation sensitivity were measured throughout the visual field as a function of meridian, eccentricity, and luminance. The stimulus conditions were designed to excite preferentially the long-wavelength-sensitive (R) cones in equal numbers at each retinal location. Temporal-frequency responses under these conditions can be partitioned into two components by following the analysis of Kelly [J. Opt. Soc. Am. 51, 422 (1961)]: a high-frequency linear component unaffected by the mean luminance level and a nonlinear adaptive component that conforms to Weber's law of proportionality to luminance. The results suggest that the time constant of the linear component varies to some extent with meridian at a constant eccentricity, in addition to the substantial increase with eccentricity along all meridians. Retinal variations in sensitivity of the nonlinear, adaptive aspect of the visual response were small when equal numbers of cones were stimulated, and the variations did not account for the changes in CFF with either eccentricity or meridian.

The combined effects of alcohol consumption and cigarette smoking on critical flicker frequency

Previous studies have found that subjects report a raised critical flicker frequency (CFF) threshold after smoking a cigarette and a lowered CFF after drinking a moderate dose of alcohol. The present aim was to examine the joint effects of these two drugs on CFF. Although the changes in CFF were in the expected direction for each drug separately, the combined effects were variable, depending in part on the type of test being used. In a lengthy signal detection task (Experiment I), combining the drugs resulted in antagonism, but with short probe tests (Experiments II and III), the smokers showed little effect for alcohol alone, but decreased threshold if they were allowed to smoke at the same time. Experiment IV examined the effects of both drugs on long and short threshold tests within the same session, essentially confirming the previous findings. Additional pre-drug threshold differences were found between smokers who were required to refrain from smoking overnight before testing and those who were nondeprived.

Effect of hydroxyzine on human vigilance

Critical flicker frequency (CFF) is a neurophysiological variable which can be measured precisely and which shows little diurnal fluctuation. In a double blind cross-over study on six male volunteers, hydroxyzine hydrochloride 25 mg caused sedation that was recognised subjectively. It was also assessed quantitatively by changes in CFF in which the effect of hydroxyzine appeared after the second hour, persisted during the third and fourth hours, but had disappeared after the seventh hour.

Changes in critical flicker frequency during prolonged visual deprivation

Subjects were tested on the critical flicker frequency during a 1-week period of visual deprivation (either homogeneous illumination or darkness). Deprived subjects showed no significant differences from a confined control group. Results were discussed in relation to previous research, Schultz’s theory of “sensoristasis” and Sharpless’ revision of the “law of denervation.”

Changes in critical flicker frequency during and after fourteen days of monocular deprivation.

ALTHOUGH the technique of monocular occlusion has long been used by ophthalmologists1 in the therapeutic treatment of such conditions as strabismus (squint) and amblyopia, particularly in young children, little experimental work has been directed at determining the nature of visual sensitivity in the nonoccluded eye. Will this eye show a compensatory improvement in acuity as a result of prolonged disuse of the other eye, and, if it does, will this effect dissipate with time following removal of the occluding eye patch? In an attempt to throw some light on this important applied and theoretical problem we have recently conducted a series of studies2 in which the critical flicker fusion frequency (CFF), a measure of temporal visual acuity, was determined in adult subjects, with normal vision, at periodic intervals during 7 days of monocular deprivation. No significant changes in the CFF of the occluded eye were observed. The temporal pattern of the nonoccluded eye, however, was characterized by an initial decrease in the CFF at 3 and 6 h (that is, poorer acuity), a reversal to the pre-experimental baseline at 9 h, and then a negatively accelerating improvement in performance as a function of monocular deprivation duration. This temporal pattern occurred regardless of whether the dominant or nondominant (weak) eye was occluded. Furthermore, these results were only obtained if a black rather than a white translucent eye patch was used, a finding which indicates that our monocular phenomenon was produced by an absence of visual stimulation per se and not by an absence of pattern vision.