PubMed Health⌕ Search

Biomedical subjects

M Molnár

Publications and source records attributed to M Molnár.

At least 73 records · Page 4Linked to original sources
PubMed1988

Effect of atropine on intracortical evoked potentials during classical aversive conditioning in cats.

In this article, intracortical evoked potentials (EPs) were recorded simultaneously from six different depths of the auditory cortex of freely moving cats. The effect of (a) different states of vigilance and that of atropine, (b) classical aversive conditioning, and (c) the effect of atropine during conditioning was studied on the intracortical EP profiles. Atropine induced EP changes that were similar to those seen in slow wave sleep. During classical aversive conditioning signal stimuli elicited a middle-latency negative EP component which was localized to the superficial cortical layers. Atropine (2 mg/kg body weight) did not abolish the appearance of this component but only increased its latency. It is proposed that the cholinergic part of the ascending activating system did not play an essential role in its generation.

Animals↗
PubMed1987

Evoked potential correlates of stimulus deviance during wakefulness and sleep in cat--animal model of mismatch negativity.

Auditory evoked potentials (EPs) elicited by standard (STs) and deviant tones (DTs) of different probabilities were studied in freely moving cats during wakefulness and sleep. A large double peaked negativity, so-called mismatch negativity (MMN), was evoked by the unattended low probability DTs. The EPs recorded from the AI and AII areas of the auditory cortex showed more dynamic changes than the vertex and association cortical responses. The amplitude of the MMN was inversely proportional to the probability of DTs. The latency of the MMN showed dependence both on the location of the recording site and on the probability of DTs. During slow wave sleep (SWS) the MMN of increased latency could be evoked only at the lowest probabilities. The cortical distribution of the MMN changed in the SWS.

Animals↗
PubMed1987

Differential effects of prostaglandin F2 alpha and of prostaglandins E1 and E2 on cyclic 3',5'-monophosphate production and intracellular calcium mobilization in avian uterine smooth muscle cells.

The effects of prostaglandins (PGs) E1 (PGE1), E2 (PGE2) and F2 alpha (PGF2 alpha) on cyclic 3',5'-adenosine monophosphate (cAMP) production and intracellular Ca mobilization were examined in smooth muscle cells of chicken uterus grown in primary culture. At subnanomolar concentrations, both PGE1 and PGE2 significantly suppressed cAMP levels. However, at higher concentrations (0.1-100 microM), both agonists caused a dose-related increase in cAMP production. PGF2 alpha, on the other hand, had no effect on cAMP production. Forskolin (1-100 microM), which also stimulated cAMP production in a dose-dependent fashion, potentiated the effects of both PGE1 and PGE2. In digitonin-permeabilized uterine cells preloaded with 45Ca2+, the addition of PGF2 alpha caused a biphasic 45Ca2+ efflux. There was a small but significant 45Ca2+ release (10.0 +/- 1.5%) within 30 s (rapid phase), followed by a larger one (32.0 +/- 2.0%) within 5 min (slow phase). PGE2, at doses above 1 nM (which significantly increased cAMP accumulation), promoted 45Ca2+ sequestration. This action of PGE2 was observed as early as 1 min and was complete by 5 min. In addition, 0.001 nM PGE2 (a dose that was ineffective on 45Ca2+ mobilization) enhanced PGF2 alpha-induced 45Ca2+ mobilization from 22.5 +/- 5% to 57.0 +/- 3.5%. These results show that PGs of the E series have distinctly different effects on cAMP production and intracellular Ca mobilization. PGF2 alpha action may be linked directly to intracellular Ca mobilization, whereas the effects of PGE may be exerted at multiple sites depending on its local concentration. At low concentrations, its action may be mediated by the suppression of cAMP levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗
PubMed1987

Effects of signal probability on sensory evoked potentials in cats.

The present experiment was designed to follow the evoked potential (EP) changes recorded from the association cortex and A II area of the auditory cortex and from the vertex of the freely moving cat. The EPs elicited by clicks of different probabilities used as warning stimuli during aversive conditioning were analyzed. It was found that the EPs recorded from the auditory cortex and the vertex showed different changes during the aversive conditioning to the rare clicks of 3 and 10% probabilities. The N50 and P100 components of the auditory cortical (A II area) EPs increased significantly at both signal probabilities. On the vetex and association cortical EPs, elicited by the rare signals, a broadly distributed positivity, the P250 wave could be detected. The amplitude increase of the P250 was inversely proportional to the used probability of the signal.

Acoustic Stimulation↗
PubMed1986

Laminar analysis of intracortical auditory evoked potentials during the wakefulness-sleep cycle in the cat.

Click-elicited evoked potentials (EPs) were recorded simultaneously in six different depths of the auditory cortex of freely moving cats during the wakefulness-sleep cycle. Chronically implanted multielectrodes designed especially for this purpose were used. The clicks were given through a bone conductor and middle ear muscles were cut to keep the acoustic input constant. The EPs recorded in different cortical depths changed in different ways during the wakefulness-sleep cycle as evidenced by both the early and middle latency components. The amplitude of the middle latency components was the largest in slow wave sleep (SWS) in all cortical depths. The early deep negative wave was the smallest in paradoxical sleep (PS) probably indicating a reduced sensory input. In the aroused state a negative component of approximately 60 ms appeared localized to the superficial layers. The lack of a true phase reversal of the early components, their independently changing amplitudes and the homogeneous polarity of the later waves in the different cortical depths do not support the idea of simple dipole processes that could explain their generation.

Animals↗
PubMed1986

Evoked potential components in the layers of the auditory cortex of the cat.

The intracortical distribution of evoked potentials was studied by seven-contact multielectrodes implanted into the primary auditory cortex of freely moving cats. The aim of the study was to compare the intracortical profiles of the responses evoked by click stimuli and by electrical stimulation of the medial geniculate body in different states of alertness and in Nembutal anesthesia. Only the early surface positive component showed phase reversal in the depth of the cortex. The middle latency components which were faithful indicators of vigilance appeared without phase reversal. Nembutal wiped out these components. A negative component of about 50 ms latency appeared in the attentive animal which had the highest amplitude close to the surface and decreased toward the depth indicating that it was generated in the most superficial layers of the cortex. The stimulation of the last nucleus of the specific auditory pathway elicited evoked potential patterns including also the middle latency components, which were closely similar to those induced by click stimuli.

Animals↗
PubMed1986

Comparison of evoked potential changes during classical and instrumental conditioning in cats.

The waveform changes of cortical evoked potentials to click conditioned stimuli were analyzed by a complex computer program developed for sorting nonhomogeneous series of evoked potentials. The changes of evoked responses manifested themselves mainly in the middlelatency waves, while the first components showed only a slight fluctuation during the whole conditioning. A late negative component of 40-50 ms latency was clearly related to the attentive state of the animal. The evoked potentials with increased negative component appeared in different sequences in 'the two conditioning paradigms and in the different phases of the learning process.

Animals↗
PubMed1985

Combined effects of amantadine and interferon on influenza virus replication in chicken and human embryo trachea organ culture.

Amantadine (greater than or equal to 100 micrograms/ml) treatment of chicken or human trachea organ cultures 6 h before infection inhibited influenza virus replication. Chicken or human leukocyte IFN evoked antiviral resistance in the cells of the homologous organ cultures only at a concentration of 100 U/ml or more. Treatment of organ cultures with combinations of the two substances resulted in an additive effect on influenza virus replication in both chicken and human tissues.

Amantadine↗
PubMed1985

Simultaneous occurrence of diabetes mellitus and coeliac disease.

Subtotal villous atrophy in the proximal jejunum was observed in six patients affected by juvenile diabetes. Introduction of gluten free diet invariably led to clinical improvement, in the four patients in whom also rebiopsy was performed the jejunal mucosa exhibited improvement. In all cases gluten sensitive enteropathy was diagnosed after the onset of diabetes. Marked stunting in growth, strikingly labile carbohydrate tolerance, pronounced proneness to hypoglycaemia or development of Mauriac's syndrome were the symptoms pointing to coeliac disease. Protracted diarrhoea was seen only in two patients, pronounced deceleration in weight development occurred in none of the six children. In four patients out of six the presence of both HLA B8 and DR3 antigens was demonstrated, in a fifth patient only DR3 was present; this suggests a common genetic background of the simultaneous occurrence of the two disorders. Untreated coeliac disease aggravates preexisting diabetes. The importance of early recognition of latent coeliac disease is stressed.

Celiac Disease↗