Biomedical subjects

V Komárek

Publications and source records attributed to V Komárek.

17 recordsLinked to original sources

PubMed2001

Synchronization as adjustment of information rates: detection from bivariate time series.

An information-theoretic approach for studying synchronization phenomena in experimental bivariate time series is presented. "Coarse-grained" information rates are introduced and their ability to indicate generalized synchronization as well as to establish a "direction of information flow" between coupled systems, i.e., to discern the driving from the driven (response) system, is demonstrated using numerically generated time series from unidirectionally coupled chaotic systems. The method introduced is then applied in a case study of electroencephalogram recordings of an epileptic patient. Synchronization events leading to seizures have been found on two levels of organization of brain tissues and "directions of information flow" among brain areas have been identified. This allows localization of the primary epileptogenic areas, also confirmed by magnetic resonance imaging and pasitron emission tomography scans.

Journal Article↗

PubMed2000

Interstrain differences in cognitive functions in rats in relation to status epilepticus.

Cognitive functions of Long Evans (N=30) and Wistar rats (N=32) were compared using a Morris water maze. Under control conditions the Long Evans rats were more efficient in this test, their average escape latency after 5 days of training (6.4+/-0.1 s, mean+/-S.E.M.) was significantly shorter than that of the Wistar rats (11.0+/-0.1 s). When the training was completed seizures were induced by an intraperitoneal injection of pilocarpine (330 mg/kg in the Long Evans strain and 350 mg/kg in the Wistar rats) 30 min after pretreatment with N-methylscopolamine (1 mg/kg i.p.). Clonazepam (1 mg/kg i.p.) was used to interrupt clonic seizures after 2 hours of continuous activity. Approximately one quarter of rats in both strains did not develop seizures. Severe convulsive status epilepticus was common in Long Evans rats (23 out of 30). In contrast, only 12 Wistar rats generated convulsive status epilepticus and the same number of animals exhibited only bursts of motor seizures separated by periods without convulsions (temporary seizures). Mortality after pilocarpine-induced status epilepticus was considerably higher in the Long Evans rats than in the Wistar rats. After a latency of 2-3 weeks spontaneous recurrent seizures appeared in all animals surviving status. Cognitive memory was tested during the 'silent period' between status and recurrent seizures. The Long Evans rats were unable to find the platform at the 3rd and 6th day after status but then their performance rapidly improved. The performance of the Wistar rats undergoing status epilepticus was seriously deteriorated and it never normalized, whereas the animals with temporary seizures exhibited only a transitory marginal prolongation of latencies. The hippocampal formation was damaged by status epilepticus in rats of both strains - the Long Evans rats exhibited more extensive damage of subfields CA1 and CA3, whereas in the Wistar rats a complete destruction of hilar neurons was observed in addition to partial CA1 and CA3 damage.

Animals↗

PubMed1999

Cognitive functions after pilocarpine-induced status epilepticus: changes during silent period precede appearance of spontaneous recurrent seizures.

PURPOSE: To study the possible relation between spontaneous recurrent seizures (SRS) and the derangement of cognitive memory. METHODS: Status epilepticus (SE) was induced in adult Long-Evans rats by pilocarpine (320 mg/kg, i.p.) and interrupted after 2 h by clonazepam (CZPs mg/kg, i.p.). In addition to the animals that were given pilocarpine and CZP (group P), two groups received ketamine (100 mg/kg, i.p.): the first group 15 minutes after SE onset (group K15), and the second immediately after the CZP (group K120). Control groups were formed from animals not treated with pilocarpine as well as animals that received pilocarpine but did not develop motor seizures. Spatial cognitive memory was tested in the Morris water maze. RESULTS: Testing was impossible for more than 6 days after SE in group P. Ketamine shortened this period for the two groups that received it. During the silent period, deteriorated cognitive memory progressively improved, but the performance of group P started to worsen before the appearance of SRS. Group K120 only expressed a tendency toward declining performance, whereas group K15 never developed SRS, and the behavior of these animals did not differ from that of the controls after the postseizure period was over. Histologically, massive hippocampal cell loss was seen in group P. Ketamine protected hippocampal cells in a time-dependent manner; group K15 did not exhibit any obvious necrosis in the hippocampus. CONCLUSIONS: There is no close relation between cognitive functions and the appearance of SRS, because ketamine, administered 120 min after the beginning of SE, prevented the derangment of cognitive functions but not the appearance of SRSs.

Animals↗

PubMed1998

1H MR spectroscopy in patients with mesial temporal epilepsy.

The study provides a review of the basic examination procedures and results of proton magnetic resonance spectroscopy (1H MRS) in patients suffering from mesial temporal lobe epilepsy (MTLE). The source of seizures in MTLE is most often an epileptogenic focus secondary to hippocampal sclerosis. 1H MRS currently plays an important role in the non-invasive diagnosis of this type of epileptogenic lesion. The decisive 1H MRS parameter characterizing an epileptogenic lesion is a statistically significantly decreased value of N-acetylaspartate levels compared with control values, most often associated with a decrease in the ratios of the intensities of NAA/Cr, NAA/Cho and NAA/(Cr + Cho) signals. Moreover, MRS makes it possible to distinguish bilateral involvement of mesial temporal structures typically associated with a bilateral decrease in the levels of metabolites and/or their ratios. As regards other metabolic compounds which play an important role in the pathobiochemistry of epilepsy, MRS is employed to study the action of gamma-aminobutyric acid (GABA), inositol, lactate, glutamine, and glutamate, the clinical function of which has not been fully clarified as yet. It is in this context that one should consider the application of 1H MRS in evaluating the action of some new anti-epileptic agents affecting excitatory and inhibitory amino acids. There is no doubt that in vivo 1H MRS, along with other imaging methods, has made a significant contribution to the clinical and biochemical description of epileptic seizures and has assumed a prominent position among the techniques of pre-operative examination in epileptic surgery.

Aspartic Acid↗

PubMed1992

[Vaccination in children with neurologic diseases].

The authors explain the main risks of immunization of children with affections of the central nervous system. For practical reasons the diseases are divided into four groups: 1. Perinatal affections and developmental diseases of the CNS. 2. Neurodegenerative and metabolic affections of the CNS. 3. Acquired affections of the CNS. 4. Paroxysmal diseases. The objective of the paper is to reduce the risk of postvaccination complications in children with serious affections of the CNS, while ensuring the contemporary necessary vaccination rate of the population.

Child↗

PubMed1992

[Neurologic disorders after vaccination against measles and mumps].

The authors analyse neurological disorders which developed after immunization with vaccines against measles (Movivac) and after immunization against measles and mumps (Mopavac) in 60 children. The majority of reactions developed at the time of the side-reaction after immunization and was manifested by febrile attacks.

Child↗

PubMed1992

[Neurologic complications after vaccination against diphtheria, tetanus and whooping cough].

The authors analyze the character and prognosis of neurological complications after immunization against diphtheria, tetanus and whooping cough (ADTP vaccine) in children free from neurological disease in the case-history (n = 91) and in children with neurological disease in the case-history (n = 9). In both groups the most frequent type of complications were encephalopathies and febrile attacks as a consequence of metabolic and toxic changes following vaccination. Persisting neurological disorders had in both investigated groups in the majority the character of epilepsy.

Child↗

PubMed1990

[Abdominal epilepsy].

Explore the source record for details and available documents.

Abdominal Pain↗

PubMed1990

Comparative anatomy of the intestine of Cyprinus carpio Linnaeus 1758 and Salmo trutta Linnaeus 1758.

The anatomy of carp and trout was compared by means of anatomical dissection and frozen cross-sections. This enabled exact topographical localization and hence also the determination of differences in the position of individual intestinal segments. The elaboration of a suitable nomenclature was considered to be an important working measure for the facilitation of interspecific comparison.

Animals↗

PubMed1990

Body cavities in fishes.

Four types of body cavity arrangement were found in 20 species of fish (see Materials and Methods). The body cavities of fishes were also compared with those of mammals and birds. It was concluded that higher vertebrates utilized only the Tinca type for their evolution, while the other types were dead-end evolutionary forms which terminated at fish level, or possibly with amphibians and reptiles. The necessary research in these groups still remains to be done.

Animals↗

PubMed1987