Orsolya Nagy

Dissociation between medial temporal lobe and basal ganglia memory systems in schizophrenia

The purpose of this study was to investigate basal ganglia (BG) and medial temporal lobe (MTL) dependent learning in patients with schizophrenia. Acquired equivalence is a phenomenon in which prior training to treat two stimuli as equivalent (if two stimuli are associated with the same response) increases generalization between them. The learning of stimulus-response pairs is related to the BG, whereas the MTL system participates in stimulus generalization. Forty-three patients with DSM-IV schizophrenia and 28 matched healthy controls participated. Volunteers received the Rutgers acquired equivalence task (face-fish task) by [Myers, C.E., Shohamy, D., Gluck, M.A. et al., 2003. Dissociating hippocampal versus basal ganglia contributions to learning and transfer. J. Cogn. Neurosci. 15, 185-193.], the California Verbal Learning Test (CVLT), and the n-back working memory test. The Rutgers acquired equivalence task investigates BG-dependent processes (stimulus-response learning) and MTL-dependent processes (stimulus generalization) with a single test. Results revealed that patients with schizophrenia showed a selective deficit on stimulus generalization, whereas stimulus-response learning was spared. The stimulus generalization deficit correlated with the CVLT performance (total scores from trials 1-5 and long-delay recall), but not with the n-back test performance. The number of errors during stimulus-response learning correlated with the daily chlorpromazine-equivalent dose of antipsychotics. In conclusion, this is the first study to show that patients with schizophrenia exhibit deficits during MTL-dependent learning, but not during BG-dependent learning within a single task. High-dose first generation antipsychotics may disrupt BG-dependent learning by blocking dopaminergic neurotransmission in the nigro-stiratal system.

Dopaminergic contribution to cognitive sequence learning

Summary.Evidence suggests that dopaminergic mechanisms in the basal ganglia are important in feedback-guided habit learning. To test hypothesis, we assessed cognitive sequence learning in 120 healthy volunteers and measured plasma levels of homovanillic acid [HVA] (a metabolite of dopamine), 5-hydroxyindoleacetic acid [5-HIAA] (a metabolite of serotonin), and 3-methoxy-4-hydroxypheylglycol [MHPG] (a metabolite of norepinephrine). Results revealed a significant negative relationship between errors in the feedback-guided training phase of the sequence learning task and the plasma HVA level. The HVA level accounted for 10.5% of variance of performance. Participant who had lower HVA level than the median value of the whole sample committed more errors during the training phase compared with participants who had higher HVA plasma level than the median value. A similar phenomenon was not observed for the context-dependent phase of the task and for 5-HIAA and MHPG. These results suggest that dopamine plays a special role in feedback-guided cognitive sequence learning.

Detection and sequencing of West Nile virus RNA from human urine and serum samples during the 2014 seasonal period

West Nile virus, a widely distributed mosquito-borne flavivirus, is responsible for numerous animal and human infections in Europe, Africa and the Americas. In Hungary, the average number of human infections falls between 10 and 20 cases each year. The severity of clinically manifesting infections varies widely from the milder form of West Nile fever to West Nile neuroinvasive disease (WNND). In routine laboratory diagnosis of human West Nile virus infections, serological methods are mainly applied due to the limited duration of viremia. However, recent studies suggest that detection of West Nile virus RNA in urine samples may be useful as a molecular diagnostic test for these infections. The Hungarian National Reference Laboratory for Viral Zoonoses serologically confirmed eleven acute human infections during the 2014 seasonal period. In three patients with neurological symptoms, viral RNA was detected from both urine and serum specimens, albeit for a longer period and in higher copy numbers with urine. Phylogenetic analysis of the NS3 genomic region of three strains and the complete genome of one selected strain demonstrated that all three patients had lineage-2 West Nile virus infections. Our findings reaffirm the utility of viral RNA detection in urine as a molecular diagnostic procedure for diagnosis of West Nile virus infections.

How well do patients with schizophrenia track multiple moving targets

It has been demonstrated that patients with schizophrenia perform poorly on tasks that require orienting, focusing, maintaining, and shifting attention. However, it is unknown how patients with schizophrenia can track multiple moving targets. To elucidate this issue, the authors investigated fast and slow multiple-object tracking in patients with schizophrenia (n = 30) and in matched healthy control participants (n = 30) and assessed their relationship with motion perception (velocity discrimination), sustained attention and context processing (Continuous Performance Test, 1-9 version; J. R. Finkelstein, T. D. Cannon, R. E. Gur, R. C. Gur, & P. Moberg, 1997), and object and spatial working memory. Results revealed that patients with schizophrenia displayed impaired performances on multiple-object tracking tasks. Linear regression analysis revealed a specific relationship among object tracking, velocity discrimination, and spatial working memory. In patients with schizophrenia, velocity discrimination and spatial working memory were the predictive factors of multiple-object tracking, whereas in healthy control participants, the single predictive factor was velocity discrimination. Probabilistic regression analysis revealed that only the Continuous Performance Test made significant contribution to discriminating between patients and control participants. These results suggest that multiple-object tracking is impaired in schizophrenia, and that it is specifically associated with motion perception and spatial working memory.

Are we protected? Imported measles - on the way to eradication.

In accordance with the 2015 regional goal for measles and rubella elimination of the WHO European Region, only a few imported cases have been documented of both diseases in Hungary for years.This paper presents a case of a Hungarian woman, born in 1975, who received measles vaccination at age of 12 months and later at age of 11 years, according to her certificate of vaccination. In 2009, after arriving home from a vacation in Ireland, she developed acute measles infection with clinical symptoms. It was confirmed by the detection of measles specific IgM, IgA and IgG antibodies, and by detection of viral nucleic acid from throat swab in virus transport medium.Additionally, an outbreak occurred in December of 2011 among a family emigrated from Romania to Hungary. No new measles cases were diagnosed among the contact persons of neither the young Hungarian woman returning from Ireland, nor the family emigrated from Romania. This observation refers to the effectiveness of the Hungarian vaccination program.

First detection of tick-borne encephalitis virus RNA in clinical specimens of acutely ill patients in Hungary

Tick-borne encephalitis virus (TBEV) is one of the endemic flaviviruses in Hungary, which is responsible for human infections every year. Neurological involvement in the disease is characterized by meningitis, encephalitis or meningoencephalitis which can result in long-term neurological and neuropsychiatric sequelae. Microbiological diagnosis of acute cases is predominantly based on serological tests due to the limited duration of viremia and long incubation period, however, the application of molecular methods can also supplement the serological diagnosis and provides epidemiological data. The aim of this study was to determine how viral RNA could successfully be detected from different body fluids of serologically confirmed acute cases. Serum, whole blood, cerebrospinal fluid and urine samples of 18 patients from the total of the 19 serologically diagnosed cases were investigated by using the RT-PCR method. Two sera and one urine sample of three patients tested positive and the European subtype of TBEV could be identified. As far as we know this was the first time that TBEV RNA could be detected from human clinical samples in Hungary. Our finding highlights that the application of molecular methods besides serological tests can be a valuable tool in differential diagnosis especially in areas like Hungary, where two or more flaviviruses are co-circulating.

A nyugat-nílusi vírus kimutatása humán betegmintákból: nyomon követéses vizsgálatok a 2015. évi szezonális időszakban

INTRODUCTION West Nile virus, a mosquito-borne viral zoonosis is responsible for human infections in Hungary. Laboratory diagnosis is based on serological tests, however the application of molecular methods has been appreciated. AIM The aim of the study was to investigate blood, cerebrospinal-fluid and urine samples of acutely ill patients and to follow-up PCR positive cases to ascertain the length of virus excretion. METHOD Clinical specimens were examined by indirect-immunofluorescent, haemagglutination-inhibition, two PCR tests and Sanger-sequencing. Virus isolation in case of two patients was successful. RESULTS A follow-up study could be carried out in case of 5 patients. Viral nucleic acid was detectable in urine even for several weeks after symptom onset and viral RNA was present at higher concentration compared with other samples. CONCLUSIONS PCR analysis of urine could provide useful epidemiological and diagnostic information. Therefore, it is recommended to collect urine samples in order to supplement the serological diagnosis. Orv Hetil. 2017; 158(20): 791-796.Absztrakt: Bevezetes: A nyugat-nilusi virus Magyarorszagon is elterjedt, eves rendszeresseggel human megbetegedeseket okozo, szunyogok altal terjesztett viralis zoonosis. Az akut infekciok laboratoriumi differencialdiagnosztikaja szerologiai vizsgalatokon alapul, de a molekularis modszerek alkalmazhatosaga is egyre inkabb előterbe kerul. Celkitűzes: Vizsgalatunk celja a 2015. evi akut fertőzottek ver-, liquor- es vizeletmintainak molekularis vizsgalata volt, illetve a pozitiv betegek nyomon kovetese annak megallapitasa erdekeben, hogy mennyi ideig detektalhato a virus. Modszer: Az akut fertőzott betegek mintait indirekt immunfluoreszcens, hemagglutinacio-gatlasi, majd ketfele PCR-modszerrel vizsgaltuk. A pozitiv mintakbol a virustorzseket Sanger-szekvenalassal azonositottuk es virusizolalast vegeztunk. Eredmenyek: Ot paciens eseten nyilt lehetőseg a nyomon kovetest elvegezni, ennek soran a betegek vizeleteből hosszu ideig (a tunetek megjelenesetől szamitva akar hetekig) es osszehasonlitva mas mintatipusok...