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Biomedical subjects

A Antal

Publications and source records attributed to A Antal.

At least 37 records · Page 2Linked to original sources
PubMed1998

Abstraction is impaired at the perceptual level in schizophrenic patients.

This study investigates category learning in schizophrenia in order to evaluate abstraction abilities at the perceptual level. The participants learned about two categories of geometric shapes. The category exemplars were presented successively. In the case of schizophrenic patients, longer exposure time and more stimulus presentations were used to counterbalance attention impairments. In spite of this, the perceptual category learning was significantly impaired in the patient group. In contrast, when the training procedure involved verbal category definition and not perceptual learning, the performance of schizophrenics was similar to that of the healthy controls. These findings suggest that the perceptual learning of categories, but not free classification judgements are impaired in schizophrenia, and that this impairment is not due to pure attentional disturbances.

Adult↗
PubMed1998

[Testing basic visual functions in the evaluation of extrapyramidal side effects of antipsychotic agents].

One of the cornerstones of antipsychotic therapy is the evaluation of the effective dose that cause minimal extrapyramidal side effects. It is known that the visual system (e. g. the retina) contains dopaminergic cells similarly to the striatum where dopaminergic blockade is crucial in the induction of extrapyramidal symptoms. This rises the possibility that striatal functions can be tested by the evaluation of certain visual functions. This study compared the visual contrast-sensitivity of 20 schizophrenic patients on antipsychotic medication (9 patients were on risperidone, 9 on haloperidol, and 1-1 on zuclopenthixol and fluanxol treatment) to that of normal control subjects, and found significant impairment in the former group. The contrast-sensitivity impairments correlated with the severity of extrapyramidal symptoms. These results suggest that contrast-sensitivity measurements can be useful in the evaluation of neuroleptic threshold in the clinical practice.

Adult↗
PubMed1998

Serologic examinations in acute appendicitis.

Authors studied the formation of endotoxic antibody level in healthy adults and in patients with appendicitis with a technique (indirect haemagglutination) not used till now. They found the antibody level against endotoxin to be increased in 91% of their patients in the postoperative period. Decrease in the antibody level against endotoxin was observed in two patients with gangrenous appendicitis and two patients with perforated appendicitis. Summarizing their results, authors consider mixed (aerobic, anaerobic) infection to be of decisive importance in the development of acute appendicitis, contributing to the weakened immune response of the host.

Acute Disease↗
PubMed1998

Visuo-cognitive dysfunctions in Parkinson's disease.

Loss of will, decreased activity, and poverty of behavior are among the common symptoms observed in Parkinson's disease (PD). In line with these clinical observations, PD patients display prominent deficit in neuropsychological tests, requiring self-generated and effort-demanding operations. However, recent evidence suggests that this impairment is not generalized: visuo-spatial working memory and attentional set-shifting seem to be selectively impaired in the early stages of the disease. Electrophysiological studies also demonstrate the dysfunction of higher-level visual information processing. In this article, we discuss some current results to show the connection between clinical symptoms and neuropsychological deficits. We also consider dysfunction in underlying neural mechanisms, with particular emphasis on the dysregulation of fronto-striatal circuits. However, it is conceivable that visuo-cognitive impairment in PD reflects dysfunction of neural assemblies, involving basal ganglia, dorsal visual stream, and frontal-prefrontal circuits.

Attention↗
PubMed1997

Dopamine D2 receptor blockade alters the primary and cognitive components of visual evoked potentials in the monkey, Macaca fascicularis.

The effects of sulpiride, a dopamine D2 receptor antagonist, were studied on visual event-related potentials in a monkey performing in a visual oddball task in order to investigate receptor specific mechanisms in visuo-cognitive processes. Following the injection of 0.35 mg/kg sulpiride i.m., the amplitude and latency of the primary (P100) and cognitive (P300) components did not change significantly. When 1.05 mg/kg sulpiride was administered, the latency of the primary and cognitive components increased. The amplitude of the P100 component decreased, while that of the P300 component increased. These data suggest that D2 receptors play an important role in visuo-cognitive processes in both physiological and pathological conditions such as Parkinson's disease and schizophrenia.

Animals↗
PubMed1997

[Cases of multiple tumors in our clinic].

Between 1989 and 1994, 719 patients had been treated with tumours at the Department of Surgery, Teaching Hospital of Semmelweis University Medical School, Budapest, Multiple tumours were found in 53 cases (7.37%), 49 of these being duplex and four triplex form. In men colorectal carcinoma was the most frequent while in women synchrone and metachrone breast cancers. Simultaneous breast tumors were most often found in senior patients (mean age 72.7) and metachrone ones at younger age (first tumor at 54.8 and the second one at 65.4 years of age, the following time being 10.6 years). Colorectal and gynecological tumours appeared with breast cancer in 5 cases. Regional colorectal tumours developed in five patients after radiotreatment of the pelvis. Familiar accumulation of colorectal cancer occurred in 4 cases. Lynch syndrome developed in 2 patients. The role of genetical factors is known in this group of illness, and they need to be screened. In this study the metachrone cancer in women occurred most frequently and only these patients received oncological treatment. The more effective treatment is supposed to enhance the number of multiplex tumours in which etiological factors also can play a role likewise mutagen effects of the first cancer therapies. The importance of collecting and processing these data is to referre to those risks, which should be considered in our everyday diagnostic work and postoperative care in these groups of patients.

Age Factors↗
PubMed1997

The totally extraperitoneal (TEP) laparoscopic hernia repair.

In recent years endoscopic techniques using mesh implantation have been added to the many options for the repair of inguinal hernia to diminish postoperative pain, shorten the reconvalescence period and improve the recurrence figures of the classical repair. The purpose of this paper is to evaluate our first experiences gained by applying the TEP laparoscopic hernia repair. Between March and December 1996, 20 laparoscopic herniorrhaphies were performed with complete extraperitoneal balloon dissection. A large polypropylene prosthesis was inserted to cover all potential defects. The follow-up was 2-10 months. There were 10 indirect, 6 direct, 1 combined direct and indirect, 1 femoral and 2 scrotal hernias. Age (26-86 years) and operative time (52-120 mins) had a wide range. Hospital stay lasted from 1-5 days. Morbidity was low: scrotal emphysema (3), peritoneal lesion (2) and palpable mesh crease (1) occurred in a few cases. No recurrences have been seen so far. It seems that the TEP laparoscopic hernia repair is a highly successful procedure with minimal morbidity. Preliminary results are promising. Further experiences and long term follow-up studies will determine the future of laparoscopic hernia surgery.

Adult↗
PubMed1996

Simultaneously evoked primary and cognitive visual evoked potentials distinguish younger and older patients with Parkinson's disease.

While it is known that both primary visual processes and visuocognitive responses are affected in Parkinson's Disease (PD), their relationship is not known. It is known that both of these measures can be affected by age per se. Our aims were to determine if in non-demented PD patients visual cognitive event-related potential (ERP) changes simply reflect abnormal primary visual processing and to determine the effects of age and disease on their relationship. In order to do so, we introduce a new normalizing procedure for visual ERPs. In addition to the latencies and amplitudes of P100, N140, P200, N200 and P300 components, the P300-P100 latency difference (termed "central processing time"-CPT) were measured. In order to avoid confounding factors of absolute amplitude differences due to say, generally low voltage recordings or poor primary visual responses, P300 responses normalized to P100 responses were also evaluated (P300/P100 amplitude ratio). Visual ERPs were obtained in an "oddball" paradigm in 20 nondemented patients with PD and 20 normal age-matched subjects. The stimuli were horizontal sinusoidal gratings differing only in spatial frequency (0.5 and 1 cycle/degree). While simple ERP latency criteria did not distinguish non-demented PD patients as a group from controls, when younger PD patients were compared to older PD patients and controls CPT acceleratedly increased in younger PD patients. The amplitudes of both N200 and P300 provided significant distinction between patient and control groups. The surprising result emerging from this study is that an individually normalized P300 amplitude provides significant distinction of younger PD patients from age matched normals.

Aged↗
PubMed1995

On the functional significance of primate retinal dopamine receptors.

Diverse dopamine receptors have been identified in the primate retina. Evidence summarized from human and monkey retinal electrophysiological studies (ERG) suggests that separate D1 and D2 receptor activation results in stimulus dependent antagonistic effects. Studies were performed using Haloperidol, 1-sulpiride, CY 208-243 and dopamine. It is inferred that the antagonistic functions of D1 and D2 receptors synergistically determine the inverted U-shaped spatial contrast response function of the primate retina. An understanding of the logic performed by retinal D1 and D2 receptors may be useful to discern properties of the role of diverse dopamine receptors in basal ganglia DA circuits.

Animals↗
PubMed1994

Visual discrimination and P300 are affected in parallel by cholinergic agents in the behaving monkey.

We studied the acute effect of cholinergic agents, scopolamine alone and scopolamine pretreatment and acetyl-L-carnitine (ALC) on visual event-related potentials (ERPs) in a monkey performing in a go/no-go visual oddball discrimination task. The same monkey was studied repeatedly for a period extending over 1.5 years. Scopolamine is known to cause cognitive impairment in primates. In the concentrations used, primary evoked potentials did not change significantly whereas P300 latency increased maximally 20-40 min following scopolamine administration. Acetyl-L-carnitine on its own increased P300 amplitude and decreased its latency. When ALC administration was preceded by scopolamine, both P300 latency and amplitude maximally increased in 25-45 min. Apparently ALC's effect on the latency and amplitude of visual P300 of the monkey is largely via muscarinic mechanisms. Our results suggest that scopolamine may provide a valuable tool to separate cognitive from primary visual processes.

Acetylcarnitine↗
PubMed1993

The effect of levo-acetyl-carnitine on visual cognitive evoked potentials in the behaving monkey.

We studied acute and chronic effects of levo-acetyl-carnitine (LAC) on event-related potentials (ERPs) in 3 monkeys trained in a "go"/"no-go" visual "oddball" discrimination task. The stimuli were 2.5 cpd sinusoidal gratings differing in their respective orientation only (0 degrees or 45 degrees). Each monkey was trained to release a lever during a prespecified time window. Target stimulus presentation probabilities were between 0.25 and 0.5. ERPs had comparable mean latencies and amplitudes in all monkeys. Primary evoked potentials recorded to either the target or non-target stimulus did not change significantly as a result of LAC treatment. On the other hand, P300 latency decreased following LAC administration, with a maximum occurring in 15-20 min. The major effects of LAC were consistent within each animal and for all three of them.

Acetylcarnitine↗
PubMed1993

Juvenile delinquency and drug dependence in Hungary.

It is regretable that the delinquency has increased in Hungary over the past 15 years. This fact occurred because criminality increased to a greater extent than average, and this means a steady supply of adult criminals. According to the surveys of the forensic psychiatrical records carried out over the 4 years between 1987-1990 in archival material of our Department, the criminological factors which occurred most frequently in juvenile delinquency among the 14-18-year-old age group are immature personality, endangered family background and inadequate school attendance. Thirty percent of criminal acts could be connected with alcoholism, 65% with theft, and 22% with aggressive delinquency. An important role in the increasing juvenile delinquency must be attributed to the crisis of the previous regime, including the faulty endeavours in child and youth protection and the inefficient school system. The decrease in living standards and the employment of women in work contributed to the loosening of family relations and the dereliction of children's education. The proportion of institutional young people among the perpetrators is high. Another factor with regard to the disadvantageous situation is the migration of young people to the towns from villages. Without the necessary conditions and with the poor company of friends, this presents an intensified criminological danger. Prevention is obviously of outstanding importance. The improvement of the economic situation, stability of families, substantial changes in school reform, the fight against alcoholism and the modern judicial regulation can be the means to achieve this goal.

Adolescent↗
PubMed1993

Animal models of Alzheimer's Parkinson's and Huntington's disease. A minireview.

Animal studies have contributed significantly to deeper understanding of several neurodegenerative disorders but fully developed models are lacking. The best models to study motor, sensory and cognitive changes and the effects of therapeutic attempts are rodents and non-human primates. This review describes neuropharmacologic, neuroanatomic and behavioral features of animal models of Alzheimer's, Parkinson's and Huntington's disease.

Alzheimer Disease↗
PubMed1993

Visual and visual perceptual disorders in neurodegenerative diseases.

Optic neuropathy is reported to occur in 10-30% of patients, while retinopathy is characteristic of type III OPCA. The use of visual and visual electrophysiological tests in early diagnosis and classification is promising. The relationship between visual impairment and other manifestations of these diseases has not been explored.

Brain Diseases↗
PubMed1993

Deep sensibility of the mystacial pad in the rat and its cortical representation.

The cortical representation of the rat's mystacial pad was examined with the aid of evoked field potentials and recording of single cell activity. Mechanical bending of the vibrissae activated the well-known area within the somato-sensory cortex. Electrical stimulation of the mystacial pad with inserted needle electrodes, bi- and monopolarly, caused a widespread activation extending practically to the whole exposed cortex, including visual, acoustic and motor areas (MSS potentials). The evoked field potentials were accompanied by well-recordable unit activity, mainly in the upper 1000 microns of the cortical depth. Capsaicin, injected into the mystacial pad on the 8th-10th postnatal day heavily impaired the MSS potentials as recorded at 2 months of age, and only moderately acted on the mechanically evoked potentials. So did also the acutely injected capsaicin. Peak latency of the MSS potentials seemed to be in correlation with the distance from the punctum maximum. The latencies of unit potentials, however, did not show such dependence, they were between 8 and 10 ms. MSS potentials are thought to represent cortical projection mainly of thermo- and nociceptive fibers, which play an important role in the early postnatal life.

Animals↗
PubMed1992

[Laparoscopic appendectomy].

We have performed the first laparoscopic appendectomy in Hungary. Laparoscopic appendectomy is a new, minimally invasive method in abdominal surgery. We consider it a worthwhile alternative to classical appendectomy.

Adolescent↗
PubMed1992

Late consequences of cryogenic brain lesion in rat; an electrophysiological study.

The left somatosensory cortex of PVG/C rats was subjected to a transcranial cold lesion, spontaneous and evoked cortical activity was studied 2-3 weeks after the lesion. The spontaneous activity underwent a depression at the focus of the lesion. Close to the epicentre of the lesion, the amplitude of the potentials evoked by electrical stimulation of the contralateral whisker pad was considerably smaller than in the controls and an almost complete reduction of the initial positive phase was found. Perifocally, 3-4 mm from the epicentre, evoked potentials with enhanced amplitudes were recorded in all experiments. It seems that considerable damage took place at the epicentre of the lesion, while perifocally an excitatory (and/or inhibitory?) mechanism was activated.

Animals↗