Saccadic latency in hepatic encephalopathy: a pilot study

Hepatic encephalopathy is a common complication of cirrhosis. The degree of neuro-psychiatric impairment is highly variable and its clinical staging subjective. We investigated whether eye movement response times—saccadic latencies—could serve as an indicator of encephalopathy. We studied the association between saccadic latency, liver function and paper- and pencil tests in 70 patients with cirrhosis and 31 patients after liver transplantation. The tests included the porto-systemic encephalopathy (PSE-) test, critical flicker frequency, MELD score and ammonia concentration. A normal range for saccades was established in 31 control subjects. Clinical and biochemical parameters of liver, blood, and kidney function were also determined. Median saccadic latencies were significantly longer in patients with liver cirrhosis when compared to patients after liver transplantation (244 ms vs. 278 ms p < 0.001). Both patient groups had prolonged saccadic latency when compared to an age matched control group (175 ms). The reciprocal of median saccadic latency (μ) correlated with PSE tests, MELD score and critical flicker frequency. A significant correlation between the saccadic latency parameter early slope (σE) that represents the prevalence of early saccades and partial pressure of ammonia was also noted. Psychometric test performance, but not saccadic latency, correlated with blood urea and sodium concentrations. Saccadic latency represents an objective and quantitative parameter of hepatic encephalopathy. Unlike psychometric test performance, these ocular responses were unaffected by renal function and can be obtained clinically within a matter of minutes by non-trained personnel

Alcohol-Related Context Modulates Performance of Social Drinkers in a Visual Go/No-Go Task: A Preliminary Assessment of Event-Related Potentials

Background Increased alcohol cue-reactivity and altered inhibitory processing have been reported in heavy social drinkers and alcohol-dependent patients, and are associated with relapse. In social drinkers, these two processes have been usually studied separately by recording event-related potentials (ERPs) during rapid picture presentation. The aim of our study was to confront social drinkers to a task triggering high alcohol cue-reactivity, to verify whether it specifically altered inhibitory performance, by using long-lasting background picture presentation. Methods ERP were recorded during visual Go/No-Go tasks performed by social drinkers, in which a frequent Go signal (letter “M”), and a rare No-Go signal (letter “W”) were superimposed on three different types of background pictures: neutral (black background), alcohol-related and non alcohol-related. Results Our data suggested that heavy social drinkers made more commission errors than light drinkers, but only in the alcohol-related context. Neurophysiologically, this was reflected by a delayed No-Go P3 component. Conclusions Elevated alcohol cue-reactivity may lead to poorer inhibitory performance in heavy social drinkers, and may be considered as an important vulnerability factor in developing alcohol misuse. Prevention programs should be designed to decrease the high arousal of alcohol stimuli and strengthen cognitive control in young, at-risk individuals.This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Slowing of human arm movements during weightlessness : the role of vision

The prevalence of dental caries in children worldwide is very high. This PhD thesis investigated and compared the effectiveness of three oral healthcare protocols - the Conventional Restorative Treatment (CRT), the Atraumatic Restorative Treatment (ART), and the Ultra-conservative Treatment (UCT) - in preventing and treating dentine carious lesions in mixed-dentitions of 6-7-year-old schoolchildren from Paranoá, a deprived suburban area of Brasília, Brazil. This thesis presents clinical trials regarding: the survival of CRT and ART restorations in primary molars; the survival of primary molars that presented intact and defective restorations; the caries-preventive effect of supervised tooth brushing, composite resin and ART sealants; the survival of retained composite resin and ART sealants using different assessment criteria; and the long-term effect of supervised tooth brushing on levels of visible plaque and gingival bleeding among schoolchildren. The findings of this thesis support the use of ART restorations as a viable option to replace amalgam for managing cavitated dentine carious lesions in single-surfaces in primary molars and daily supervised tooth brushing at school and the application of ART sealants for preventing the occurrence of dentine carious lesions in first permanent molars. They further question the need to re-restore defective restorations in primary molars and show the benefit of supervised tooth brushing for obtaining a clean dentition in this age group. Oral healthcare protocols that are more accessible to the populations and that act on the causes of the disease, such as ART and UCT, seem to be the best options to reduce the burden of dental caries and to improve children’s oral health and quality of life

The Study of CSC Strip Readout Electronics Operation at High Background Rates

The influence of the background rate on the operation of cathode strip chamber ( CSC) readout electronics has been studied. The investigation has been performed with two different cathode readout electronics: 16-channels preamplifier-shapers based on GASPLEX and Minsk ASIC "Katod-1". The first one have been tested with 4-layer 0.5´0.5 m2 CSC. One layer has been irradiated by X-ray tube ( Eg=8KeV) while the others - used for cosmic muon track coordinate reconstruction. Electronics based on Minsk ASIC have been tested with P3 prototype of ME1/1 CSC in pion beam at H2 experimental area. For both electronics the background contribution to the registered events as a function of the background rate are presented