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Biomedical subjects

J Pokorný

Publications and source records attributed to J Pokorný.

At least 19 recordsLinked to original sources
PubMed1998

Effect of edible oils and oil emulsions on the perception of basic tastes.

The intensity of sweet, bitter or astringent tastes is reduced by consumption of edible oil or oil emulsions immediately before the ingestion of test solutions. The basic taste substances were dissolved in 30% aqueous ethanol, flavoured with plant extracts. The time-intensity dependence was influenced similarly. The sensitivity of taste receptors returned to the original value within 15-20 min. Intensities of acidic or salty tastes were not affected.

Catechin↗
PubMed1998

Sensory evaluation of stored and rancid edible oils.

The sensory evaluation of stored and rancid edible oils is substantially influenced by tasting of the previous sample. Oil forms a film on walls of the oral cavity, modifying the access of active substances to taste receptors, and inhibiting the evaporation of volatiles to olfactory receptors. Intensities of different off-flavours decrease, while the flavour acceptancy increases. About 5-10 min after the first sensory test, the response of sensory receptors returns to the original sensitivity.

Brassica↗
PubMed1998

Prediction of odour and flavour acceptances of white wines on the basis of their colour.

The colour of Moravian white wines was evaluated instrumentally, using the trichromatic method, and by sensory analysis. The odour and flavour acceptances could be predicted very well on the basis of sensory colour evaluation, and less efficiently by instrumental method. Consumers preferred wines with prevailing yellow hue, which was associated with sweet, fruity and floral flavour notes. Green hue was considered a negative factor, without any rational relation to negatively perceived flavour notes. Logarithmic relations fit moderately better experimental results than linear relations.

Color↗
PubMed1998

[Developmental neuronal plasticity and its importance in the recovery and function of neural tissue].

Plasticity is understand as a natural ability of the nervous tissue to respond to intrinsic and extrinsic stimuli by means of functional or structural changes. All its manifestations, including the developmental changes and processes of recovery are controlled by general genetic programs. One of the major research goals in the field of neuroplasticity is to design a strategy for the activation of the functional recovery. Enough evidence has shown that the internal environment of the nervous tissue is one of the decisive factors which determine the degree of both the developmental and regenerative plasticity. To improve capacity for the recovery it is therefore necessary to activate these intrinsic neuroplastic mechanisms. One alternative is the method of implantation of the embryonal nerve cells suspension into the site of neuronal lesion. The grafted cells can either replace the lost cells or they might become a source of stimulating factors which may activate the process of recovery. In the model of the intrahippocampal pathways interruption (experimental partial elimination of granule cells in the dorsal blade of the dentate gyrus), the subsequent implantation of embryonal neurons of the same origin into the site of lesion can partly restore the structural pattern of the gyrus dentatus and probably preserve some of the afferent connections. However, the outgrow of efferent fibers probably remains limited to the grafted tissue.

Animals↗
PubMed1997

[Natural toxic substances in food].

Foods, mainly those of plant origin and mushrooms, contain natural toxic substances. Their acute toxicity is as a rule mild, but carcinogenic and teratogenic effects cannot be ruled out. They include e.g. cyanogens, lathyrogens, hydrazines, glucosinolates and related goitrogens, cumarins, saponins, alkaloids and glycoalkaloids, biogenic amines, enzyme inhibitors, such as lectins (haemagglutinins) and trypsin inhibitors and chelating substance e.g. phytates and oxalates. These toxic substances are partly removed by technological processes. When principles of a varied diet are respected, the health risk is reduced to a minimum.

Plants, Edible↗
PubMed1997

Neuroprotective effects of dexmedetomidine in the gerbil hippocampus after transient global ischemia.

BACKGROUND: Cerebral ischemia induces a massive release of norepinephrine associated with neuronal death in the brain. It has been demonstrated that alpha2-adrenoceptor agonists decrease the release and turnover of noradrenaline, and this might prove advantageous in counteracting the neurodegeneration in ischemic brain. Therefore, in the present study, the authors tested whether dexmedetomidine, a selective alpha2-receptor agonist, has neuroprotective effects in a gerbil transient global ischemia model. METHODS: Ischemia was induced by bilateral carotid occlusion for 5 min in diethylether-anesthetized normothermic gerbils. Dexmedetomidine was administered subcutaneously in four different treatment paradigms (6-8 animals/group): 3 or 30 microg/kg 30 min before and thereafter at 3, 12, 24, and 48 h after the occlusion, or 3 or 30 microg/kg at 3, 12, 24, and 48 h after the occlusion. Control animals were subjected to forebrain ischemia but received only saline injections. One week after occlusion, animals were transcardially perfused for histochemistry. Neuronal death in the CA1 and CA3 regions of the hippocampus and in the hilus of the dentate gyrus was evaluated in silver-stained 60-microm coronal sections. RESULTS: Compared with saline-treated ischemic animals, dexmedetomidine at a dose of 3 microg/kg given before and continued after the induction of ischemia reduced the number of damaged neurons in the CA3 area (2 +/- 3 vs. 17 +/- 20 degenerated neurons/mm2; P < 0.05). Also in the dentate hilus, the number of damaged neurons was reduced by dexmedetomidine (3 microg/kg) given before and continued after ischemia (5 +/- 7 vs. 56 +/- 42 degenerated neurons/mm2; P < 0.01). CONCLUSIONS: The present data demonstrate that dexmedetomidine effectively prevents delayed neuronal death in CA3 area and in the dentate hilus in gerbil hippocampus when the management is started before the onset of ischemia and continued for 48 h after reperfusion. Inhibition of ischemia-induced norepinephrine release may be associated with neuroprotection by dexmedetomidine.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1997

[Theoretical and clinical significance of neuroplasticity].

Plasticity is a specific feature of the nervous system, characterized by two basic phenomena: The first type of "functional plasticity" develops comparatively quickly, brings about mainly functional changes and is usually reversible. The second type has the features of an adaptation and affects the expression of genotype into phenotype. Neuroplastic mechanisms are triggered by various natural or artificial stimuli which may differ quantitatively (they arise in the internal or external environment) or qualitatively. Neuroplastic mechanisms are based on modulation of the signal transmission over synapses (e.g., the transmitter release, activity of postsynaptic receptors, efficiency changes in the transmission in the postsynaptic segment). They can be related to the interneuronal relations changes (e.g., number of certain types of synapses, significance of the wiring of different elements of the neuronal circuits). Resulting changes may occur in the communication between neurons (synaptic level), in the activity of the local neuronal circuits (level of local circuits) or in the relations between individual functional brain systems (multimodular level). Neuroplasticity might be based on structural changes which can be revealed by morphological methods. Such forms of plasticity are more frequent during the development, or as a reaction to injury (proliferation and decease of neurons, formation of their processes and spines, remodelling, or formation of synapses). More specific methods have determined that these changes are located on the molecular level (enzyme activity, production and release of transmitters or modulators, receptor activation, modulation of ion channels). Both levels of neuroplastic mechanisms bring about changes of functional parameters of the synaptic transmission (changes in the duration or amplitude of the membrane potentials and resulting facilitation, posttetanic potentiation or changes of opposite character). Effects of plasticity can reside either in positive or negative changes during the development (evolutional plasticity), after a short-term exposition (reactive plasticity), after long-term or permanent stimuli (adaptational plasticity), and during functional or structural recovery of the damaged neuronal circuits (reparation plasticity). Manifestations of plasticity have probably the same basis, irrespectively of the cause which has triggered them, or the brain region where they have been accomplished. (Tab. 7, Ref. 45.)

Animals↗
PubMed1996

[Mechanisms of neuroplasticity].

Primary organization of the neuronal circuits is based on the genetic program. In addition, individual elements of these circuits are able to adjust their function and structure to the changes in external and internal conditions. In a given moment, formation and rearrangement of the neuronal circuits are based on the mutual cooperation between mechanisms assuring plasticity and rigidity. Plasticity is related not only to the development of the organism or to changes in the internal or external conditions, it may also reflect the progress of some pathological states or the recovery of an injured nervous structure. Intensification of the natural neuroplastic mechanisms or the introduction of an active (or activated) neuronal tissue into the impaired circuits might improve the process of recovery in the central nervous system.

Animals↗
PubMed1995

Effect of cultivation medium on some physicochemical parameters of outer bacterial membrane.

The changes of surface charge and hydrophobicity of the outer bacterial membrane in relation to utilization of n-hexadecane were studied. For this spectrophotometric study adsorption of methylene blue and transport of gentian violet were used. The decrease in the negative charge of the bacterial strains Pseudomonas putida CCM 3423, P. aeruginosa, and P. fluorescens CCM 2115, depended on the type of growth medium. The decrease of surface charge was in the order: meat extract peptone broth > mineral medium with glucose > mineral medium with n-hexadecane. The highest permeability of the bacterial membrane for gentian violet was determined in the case of P. fluorescens grown in meat extract peptone broth. This effect can be explained by a greater hydrophobicity of the bacterial surface for this strain. In other strains a lower permeability was observed. P. fluorescens showed a greater adherence to hexadecane.

Cell Membrane↗
PubMed1994

Water as a possible factor of transmission in mycobacterial infections.

Mycobacterium kansasii and Mycobacterium xenopi are the most frequent species occurring in water in the Czech Republic. In the endemic area of M. kansasii in heavy industry and mining areas of North Moravia various mycobacterial species were detected in more than 20% of different water samples and M. kansasii was found in 1.5 to 1.9% of them, frequently in pit bathrooms and in the drinking water as well. Mycobacterium xenopi was detected in 35 and 50% of water samples collected in households of M. xenopi excretors in North Bohemia and in Prague. A nosocomial occurrence of M. xenopi was recorded in an hospital department in North Bohemia and in a rest home in Prague and all samples of water from the afflicted institutions were positive for M. xenopi. In a coal mine in Moravia a case of cutaneous involvement associated with the presence of M. marinum in mine water was also recorded. The incidence of various mycobacterial species (except of M. kansasii and M. xenopi) in spa and swimming pools in West Bohemia reached 35% positivity. Comprehensive reviews of bacteriological investigations for mycobacteria performed in the entire territory of the Czech Republic have been reported in annual reports since 1985. In the period from 1985 to 1991 a total of 5167 samples of various kinds of water samples were examined and mycobacteria were detected in 8.2 to 47.7% of them.

Czech Republic↗
PubMed1994

[Leukocyte adherence in women with ovarian carcinoma].

Dynamic follow-up of cell-mediated immunity in women with malignant neoplasms of the ovary provides more valuable information on the course of the disease than a single value. The properties of leukocytes in patients with malignant ovarian tumours must be followed up on a longitudinal basis, as a signal of an approaching relapse of the disease is apparent sooner than its clinical manifestations. It appears that changes of biophysical mechanisms participate not only in the course of malignant ovarian disease but perhaps also in its genesis.

Female↗
PubMed1992

[Significance of the complement fixation reaction in the diagnosis of the acute phase of lymphatic toxoplasmosis].

In a group of 300 sera of subjects with clinically suspect nodular toxoplasmosis the authors tested by the IgM ELISA reaction in the reverse order the importance of the complement-fixation reaction for assessment of the acute stage of the infection. In view of the revealed prolonged detection of IgM antibodies the authors used quantitative evaluation of the reaction; they consider based on a probability pattern of antibody response coefficients of 10 and above important for differentiation of a recent infection. For the suggested method of evaluation it was confirmed that low CFR titres (1:8, 1:16, 1:32) imply usually (89.5%) latent infection, titres of 1:64 chronic (42.8%) and latent infection (57.2%); in no instance onset of the disease was involved. From the titre of 1:128 onwards there is a proportional increase of the probable detection of acute infections (titre 1:1024 as much as 72.7%. However, even high titres are not unequivocal evidence of recent infection. In view of the equivocal interpretation of results of the CFR the authors recommend for assessment of the acute stage of the nodular form of toxoplasmosis examination of the suspect subject by the CFR and in case of a medium or high level assessment of IgM by the ELISA method focused on the level and dynamics of the coefficient.

Acute Disease↗