PubMed Health⌕ Search

Biomedical subjects

A V Medvedev

Publications and source records attributed to A V Medvedev.

50 records · Page 3Linked to original sources
PubMed1980

[Clinical features of schizophrenia with a malignant course in patients surviving into old age].

A total of 84 senile patients with malignant schizophrenia were examined. These pateints could be divided into 3 groups: with adolescent schizophrenia (with an onset of the disease before 24 years); with schizophrenia in middle age (with an onset of the disease from 25--35 years); with late schizophrenia (with an onset from 40--61 years). It was established, that the clinical and age-associated differences between the groups are distinct only in the initial and manifest stages of the disease. In the terminal period of the disease seen in senescence, there is a complete smoothening of the specific traits of each group, which is due to a formation of a deep defect infrequently associated with pseudosenile traits.

Adult↗
PubMed1978

[Terminal states of schizophrenia in old age].

On the basis of a study of 217 patients with terminal schizophrenic states in old age the author found it possible to distinguish 2 forms of such conditions: psychotic and deficient. The psychotic forms were expressed in syndromological polymorphic psychoses, which most frequently reflected the form of the process development and which is senescence often enough undergone pathoplastical changes. The deficiency forms were presented by apathic dementia, while the connection with the previous form of development was lost. In many cases in old age there was worsening of the states with a senile-like change of the clinical picture.

Age Factors↗
PubMed1977

[Schizophrenic outcomes with catatonic disorders in old age].

On the basis of a study of 51 patients with schizophrenia older than 60 years of age with catatonic outcome states the author accomplished differentiation of these conditiones with consideration of the character of the catatonic symptoms, as well as of the whole structure of the state. It was demonstrated that in the elderly the most diverse of the described in literature catatonic outcome states may be encountered. A significant percentage of the studied cases was with outcome states, prevalence of speech disorders and certain restoration of adaptation.

Adolescent↗
PubMedDate not supplied

[The c-fos proto-oncogene promotor is not regulated by serum, epidermal growth factor, and phorbol ester in embryonal fibroblasts transformed by E1Aad5+cHa-ras-oncogenes].

Regulation of c-fos protooncogene activity in rat embryonal fibroblasts (REF), E1Aad5-immortalized REF cells, and E1Aad5 + cHa-ras transformed REF cells has been investigated. The analysis of regulation of fos-promoter activity was done by means of transient and stable transfection of fos-CAT plasmid into immortalized and transformed cells. In parallel, the regulation of cellular c-fos as well as c-jun and c-myc genes expression has been studied. It has been found that in E1Aad5 + cHa-ras-transformed cells the expression of c-fos promoter has a constitutive, non-inducible character while in REF cells and cells immortalized by E1Aad5 the fos-promoter can be regulated by serum growth factors, EGF, and TPA.

Animals↗
PubMedDate not supplied

[Calculation of parameters of neuronal network model on the basis of analysis of power spectra of rat brain biopotentials].

On the basis of neuronal network a linearized model of power spectrum of the network stable activity was calculated with the approximation of external input by "white" noise. The power spectrum function obtained was used for approximation of the power spectra of the rats motor cortex potentials by the least squares method. As a result the network parameters modelling excitatory and inhibitory cellular and synaptic mechanisms were calculated for two rat strains differing in seizure readiness. As a result of calculations genetically predisposed to seizures KM rats were assumed to differ from unpredisposed to seizures Wistar rats in the increase of efficacy of neuronal interactions (excitatory and inhibitory) as a consequence of the enhanced neuronal "reactivity".

Animals↗
PubMedDate not supplied

[Validity of "lump approximation" for the description of overall brain electrical activity using an simulation model].

Brain rhythmic activity model on the basis of space uniform neuronal network consisting of excitatory and inhibitory elements was examined. Network activity description by "lump approximation" was compared with simulation model computation. Lump approximation parameters dependence on the properties of neurons and synapses as well as conditions of the transition between network activity types which imitate desynchronous (low voltage fast activity) and synchronous (high voltage slow waves) brain activities were obtained.

Animals↗
PubMedDate not supplied

[Spectral and coherence EEG analysis of rats differing in the level of seizure readiness].

The resting EEGs of several brain structures (motor and visual cortex, caudate nucleus and intralaminar thalamic nuclei) were submitted to spectral and coherence computer analyses in two rat strains. Genetically predisposed to convulsive state KM rats were shown to differ from nonpredisposed Wistar rats in EEG spectral properties. KM rats EEG pattern was characterized by increase of low frequencies (1-2 Hz) power and decrease of faster activity (5-12 Hz) power in cortical spectrograms as well as by decrease of caudate nucleus EEG absolute power. The coherence value between cortical or subcortical structures at below 4 Hz was intensified in KM rats. Reinforcement of cortical auto-oscillating properties manifested by ECoG synchronization in cortical-thalamic resonance interaction as well as weakening of striatal inhibitory system may constitute neurophysiological mechanisms of enhanced convulsive readiness. The probable role of mediator imbalance in these mechanisms is discussed.

Acoustic Stimulation↗
PubMedDate not supplied

[Modeling different regimes of bioelectrical activity in the brain in normal subjects and in "increased readiness" in a network of neuron-like elements].

Desynchronous (low voltage fast activity), synchronous (high voltage slow waves) as well as convulsive brain activities were stimulated by a computer model of neuronal population. Network excitatory and inhibitory elements possessed fundamental dynamic properties of real neurones. Being independent both of the excitability of elements and of external influence efficacy, synchronous (desynchronous) network activity resulted from the increase (decrease) of the average power of "neuronal" interconnections which imitated mutual and recurrent excitation and inhibition. The inhibition efficacy being reduced as compared with excitation, synchronization of elements became intensified. As a consequence, the rhythmic activity amplitude increased and the appearance of self-sustained oscillations simulating convulsive activity was facilitated. The probable mechanism of EEG activation by virtue of the reduction of mutual and recurrent excitation and inhibition efficacy as well as the significance of inhibitory mechanism deficiency for epileptogenesis are discussed.

Brain↗