Biomedical subjects

S Tóth

Publications and source records attributed to S Tóth.

129 records · Page 8Linked to original sources

PubMedDate not supplied

Age-dependent alteration of neural visual adaptation.

Age alterations of neural visual adaptation mechanisms were studied in young, adult and old rats by means of electroretinogram (ERG) registration. The age peculiarities of neural/fast adaptation appear mostly in limit states, partly in the range of low intensity light stimuli about the threshold sensitivity, partly in the range of high intensity light stimuli. In the case of low intensity light stimuli, the increase of light sensitivity in the course of neural dark adaptation was fastest and greatest in adult animals. In the retina of aged animals, no neural adaptation light sensitivity change could be detected about the ERG threshold. In the domain of medium intensity the adaptability of the aged retina is equivalent to that of young and adult ones, whereas its spatial and temporal summation ability gets worse in this domain. High intensity light stimuli rapidly narrow down the functional range of fast neural adaptation mechanism of the aged animal. Receptor cells of aged animals proved to be most vulnerable to glaring illumination and light loading.

Journal Article↗

PubMedDate not supplied

Age-dependent modification of aspecific cellular effects of the benzodiazepine flunitrazepam.

The experiments presented here demonstrate an aspecific effect of the benzodiazepine derivative flunitrazepam (FNZ). It differs in sites and mechanisms of action, both from benzodiazepine (BZ) specific effects on gamma-aminobutyric acid (GABA) blocking transmission via central BZ receptors and from BZ effects mediated by peripheral BZ receptors. The aspecific effect of FNZ can suitably be examined on isolated and identified neurons of the mollusc Lymnaea stagnalis (pond snail). The physiological sites of action are outside the synaptic zone, on the neuron somatic membrane and affect 'intrinsic' properties of membrane, including calcium, calcium-activated potassium and chloride channels. The aspecific FNZ effect exerts an influence on the metabolism of the cell by decreasing the permeability of the calcium channel, diminishing the excitability of the neuron membrane, and hyperpolarizing the cell, thus potentiating the specific effect of FNZ. The senile alterations of the neuron function intensify the aspecific effects of FNZ to such a degree that it must be taken seriously in consideration in anesthesia of elderly patients.

Journal Article↗

PubMedDate not supplied

Soluble interleukin-6 receptor in plasma and in lymphocyte culture supernatants of healthy individuals and patients with systemic lupus erythematosus and rheumatoid arthritis.

The soluble IL-6 receptor (sIL-6R) occurring in various body fluids of healthy persons and patients with various diseases is an agonist since its complex with IL-6 binds to gp130 making IL-6 receptor negative cells responsive for IL-6. The generation as well as the functional role of soluble IL-6 receptor is poorly understood. We measured the sIL-6R levels by ELISA sandwich technology in sera and in supernatants of lymphocyte cultures without and after incubations with dexamethasone. Our results indicate, that the sIL-6R levels in sera of patients with inactive systemic lupus erythematosus (SLE) and active rheumatoid arthritis (RA) were higher than those of the control group, active SLE and inactive RA. In vitro dexamethasone treatment stimulated generation of sIL-6R in both healthy persons and in active SLE, however it strongly suppressed sIL-6R in both RA groups. At mRNA level, we found that in SLE both the mRNA coding the cell-bound and an alternatively spliced variant corresponding to soluble IL-6R transcript increases, however the strong decrease of sIL6R protein in RA was not found at mRNA level.

Adult↗