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Biomedical subjects

Z Janka

Publications and source records attributed to Z Janka.

At least 55 records · Page 3Linked to original sources
PubMed1994

Platelet membrane fluidity and plasma malondialdehyde levels in Alzheimer's demented patients with and without family history of dementia.

Platelet membrane fluidity (PMF) was measured with three different fluorescent probes, 1,6-diphenyl-1,3,5-hexatriene (DPH), 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH), 3-(p-phenyl-1,3,5-hexatrienyl)phenyl-propionic acid (DPH-PA), which labeled different parts of the bilayer (the hydrophobic core and the positively and negatively charged regions, respectively) in Alzheimer's disease (AD) patients with and without a family history of dementia, and in a control group. In support of earlier findings in the literature, significantly increased PMF was found by the application of DPH in both groups with AD. The use of the fluorescence probe TMA-DPH, however, revealed no differences between the groups. In contrast, significant rigidification was observed with DPH-PA, but only in the AD group with a positive family history of dementia. The plasma malondialdehyde levels appeared to be similar in each group. Our findings are discussed in light of the controversies regarding the value of PMF measurements in AD.

Aged↗
PubMed1990

[Regional cerebral blood flow studied by single photon emission computed tomography (SPECT)].

Clinical experience based on regional cerebral blood flow investigations with 99mTc HMPAO SPECT in 164 patients is reported. The pharmacokinetics of the 99mTc HMPAO are summarised, and the important indications of the investigations are interpreted in case reports (stroke, surgical solution of intracavernous aneurysm, Alzheimer and multiinfarct types of dementias). The literature data suggest that the diagnostic possibilities with this method are good in other diseases too, this area is surveyed briefly.

Alzheimer Disease↗
PubMed1983

Veratridine-stimulated central synapses in culture: a quantitative ultrastructural analysis.

Synapses in explant cultures of fetal rat neocortex at day 18 in vitro were stimulated by veratridine (10(-4)M) for 20 min. The cultures were subsequently processed for electron microscopy and the synapses were analyzed by quantitative techniques, incorporating set mathematical treatment. The mean values of area, perimeter, and form factor of the presynaptic elements significantly increased following veratridine stimulation, compared to the values of control synapses. The length of the postsynaptic thickening also increased, while synaptic curvature did not change significantly in the veratridine group. A fivefold reduction was observed in the mean number of synaptic vesicles per presynaptic element and in the vesicle-terminal area ratio, following veratridine stimulation. The cytoplasm-terminal area ratio and the occurrence of vacuoles/cisternae significantly increased after veratridine application. Planar measurement of membranes (boundary length) of different presynaptic organelles revealed that the total membrane did not change significantly in the veratridine group. The data indicated an increase in volume and swelling of the pre- and postsynaptic elements, considerable depletion of synaptic vesicles, and preservation of the total presynaptic membrane following veratridine stimulation in nerve tissue culture.

Animals↗
PubMed1982

A morphometric study of cultured rat cerebral synapses exposed to different cationic media.

Quantitative techniques have been applied to compare the effects of high-K+, Mg2+ and Li+ media on the ultrastructure of cultured synapses alongside Na+-incubated controls. The explant cultures were prepared from 18-day-old embryonic rat cerebral cortices and maintained for 19 days in vitro. K+ -Stimulation for 25 min resulted in an increase in the mean perimeter and area of presynaptic terminals. Of these, the perimeter increase was the more pronounced, as indicated by a decrease in the value of the two-dimensional form factor. Reductions were also observed in the number of synaptic vesicles per presynaptic terminal, in the vesicle-terminal area ratio and in the synaptic vesicle density in an area adjacent to the presynaptic membrane, the latter two parameters being in positive linear correlation. The frequency of presynaptic cisternal/vacuolar profiles increased, and the synaptic curvature shifted in a positive direction. Synaptic length did not change following K+-exposure. Qualitative assessment indicated the presence of a network subjacent to the post-synaptic thickening and swelling of the postsynaptic ending after K+-stimulation. Incubation and fixation in Mg2+-media of two concentrations resulted in an increase in the number and area ratio of synaptic vesicles per terminal, and an elevation in the synaptic vesicle density in the higher Mg2+ concentration medium. Li+-treatment reduced the number of synaptic vesicles per terminal, the vesicle-terminal area ratio, and the vesicle density in the vicinity of the presynaptic membrane, while the synaptic curvature shifted in the positive direction. These changes were less pronounced than those characteristic of synapses in the K+ medium.

Animals↗
PubMed1982

Indirect ultrastructural evidence for lithium uptake by cultured rat cerebral cells through the sodium channel.

Cerebral cortices, prepared from 18-day-old rat embryos, were grown in explant cultures for 18 days. They were then incubated for 25 min in media of 3 types of cationic composition with and without tetrodotoxin and/or veratridine. Qualitative and quantitative ultrastructural observations revealed a considerable swelling of neuronal elements following veratridine exposure in both Na+ and Li+ media; this swelling was prevented by tetrodotoxin. By contrast, veratridine failed to induce swelling of neuronal profiles in a choline+ medium. The results indirectly indicate that Li+ ions enter cultured rat cerebral cells through the Na+ channels.

Animals↗
PubMed1982

Lithium entry into neural cells via sodium channels: a morphometric approach.

Rat cerebral cortical explants prepared from 18-day-old embryos were grown for 18 days in vitro. Cultures were exposed to Na+, Li+ and choline+ media, respectively, in the presence or absence of tetrodotoxin and/or veratridine, and processed for electron-microscopy. Veratridine (50 microM) induced an increase in summated and mean areas of neuronal profiles in Na+- and Li+-media but not in the choline+-medium: the summated perimeters did not change. The mean value of the neuronal form factor was significantly elevated following exposure to veratridine in a Na+- or Li+-dependent manner, indicating that the shape of the sectioned neuronal elements shifted towards an (ideal) circle. Qualitative assessment revealed an increased electron-lucency of the cytoplasm of neuronal profiles in Na+- and Li+-media containing veratridine. The veratridine-induced neuronal changes were inhibited by simultaneous addition of tetrodotoxin (1 microM) to the media. In the case of the glial cells, the values of the summated area and form factor did not change in the various experimental groups. The area of the extracellular space per unit area of sections significantly decreased in the Na+- and Li+-media following veratridine exposure; this did not occur in the choline+-medium. The results indicate a considerable swelling of the neuronal elements, reflecting cation, Cl- and water uptake following prolonged sodium channel activation in the presence of Na+ or Li+ ions. The quantitative ultrastructural data strongly suggests an entry of Li+ ions into cultured rat cerebral cells via sodium channels.

Animals↗
PubMed1982

Junctions in rat neocortical explants cultured in TTX-, GABA-, and Mg++-environments.

The occurrence of various cell-to-cell contacts and membrane specializations was quantitated in neocortical explant cultures prepared from 18-day-old rat embryos and exposed continuously to tetrodotoxin (TTX), gamma-aminobutyric acid (GABA) and an elevated level of magnesium ions (Mg++), respectively. Chronic TTX treatment resulted in a decrease in the number of synapses, paired neuronal membrane thickenings and nerve terminals with synaptic vesicles; the area of the neuronal compartment also decreased. By contrast, the gap junctions between glial cells increased, although the glial paired membrane thickenings decreased in number per unit area. Long-term GABA and Mg++ exposures did not alter significantly the occurrence of any of the cell contacts and membrane specializations analyzed when compared to control values. The results suggest an inhibitory effect of TTX on neuronal maturation and synapse formation in explant cultures of rat neocortex; this may lead secondarily to an increased demand for glial cell-to-cell communication.

Animals↗
PubMed1981

Preferential vulnerability of dendrites to lithium ion in rat brain and in nerve cell culture.

Preferential swelling and vacuolation of dendrites were observed electron microscopically in different brain regions of rats treated with LiCl in a dose of 6-18 mmol/kg for 1-6 days. The most severe fine structural changes were revealed in the hippocampus. Low-dose (0.33 mmol/kg) lithium treatment lasting for a year did not cause any morphologically detectable alterations in the rat brain. In vitro studies showed a reduction of dendro-axonal process network of neurons measured by morphometric means after lithium exposure. Using different cultures of neuronal and glial cell populations, higher lithium uptake was observed for neuron-enriched cultures.

Animals↗
PubMed1980

Steady-state distribution of lithium during cultivation of dissociated brain cells.

The formation of a steady-state intracellular lithium level was studied in the course of cultivation of dissociated nerve cell cultures obtained from chick embryonic brains. When lithium was given at a concentration of 2 mM, in the nutrient medium, at day 5, a steady state intracellular lithium content was achieved after about 30 min of incubation and it did not change significantly during the time of cultivation up to the 13th day in vitro.

Animals↗
PubMed1980

The influence of external sodium and potassium on lithium uptake by primary brain cell cultures at "therapeutic" lithium concentration.

The ionic regulating of lithium homeostasis and steady-state intra:extracellular lithium distribution in the brain can be approached by experimental methods using intact nerve cells in vitro. Primary cultures prepared from chick embryonic brain were applied to study the effect of extracellular sodium and potassium on the lithium uptake of nerve cells at 'therapeutic' lithium concentration (1.5 mM). Lithium influx and the level of steady-state intracellular lithium were significantly reduced by increasing the external sodium concentration. At physiological extracellular sodium level, the steady-state content of lithium in the brain cells was about half of that observed in the presence of 10 mM sodium in the incubation media and the value of the intra:extracellular lithium distribution ratio was below 1. External potassium (0.5 - 3mM) strongly inhibited lithium uptake of the nerve cells. Ouabain (10(-4)M) had no effect on this potassium-sensitive lithium uptake in Tyrode media. Sodium influx studied by isotope tracer methodology was higher in cultures preloaded with lithium as compared to that of the controls. It can be concluded that sodium and potassium ions, at physiological concentrations, significantly influence lithium uptake as well as the intra:extracellular lithium distribution in brain cell cultures.

Animals↗
PubMed1980

Alteration of erythrocyte phosphate transport in primary depressive disorders.

Plasma and erythrocyte phosphate levels, concentrations of red cell organic phosphate ester fractions (acid labile and acid resistant phosphate pools) and intracellular ATP content were determined in 16 patients with bipolar depression, in 14 subjects with unipolar depression as a group of primary affective disorders, in 15 patients suffering from neurotic depression and in 45 healthy controls. Simultaneous in vitro measurements were carried out to detect the exchange rates of inorganic phosphate between the extracellular phosphate pool and the different intracellular phosphate fractions, by use of 32P and applying tracer kinetic analysis. Plasma and red cell inorganic phosphate levels, passive phosphate transport and transfer of inorganic phosphate into the membrane ATP pool were significantly lowered in the primary depressive group as compared to the biochemical values observed in the neurotic group and in the healthy controls. The results suggest an alteration in anion transport across the red cell membrane in primary depressive disorders.

Adenosine Triphosphate↗
PubMed1980

Calcium-dependent potassium transport in progressive muscular dystrophy.

The rates of calcium-dependent potassium efflux of red blood cells in 9 Duchenne muscular dystrophic patients were measured. A significant decrease was revealed in the Ca-provoked K transport when compared with the rates observed in healthy controls. Results are discussed on the basis of the theory of generalized membrane defect in progressive muscular dystrophies.

Adolescent↗
PubMed1980

Clinical significance of sodium-dependent lithium transport in affective psychoses.

The steady state red blood cell/plasma lithium (Li) ratios were determined simultaneously with the in vitro rates of sodium-dependent Li transport of erythrocytes during prophylactic Li therapy in 30 unipolar, 52 bipolar forms of manic-depressive patients and in 58 nonmanic-depressive psychiatric patients as a control group. A reciprocal correlation was found between the Li ratios and the values of Na-dependent Li transport. These transport rates were in positive correlation with the steady state Li contents of red blood cells and that of the plasma. Significant differences were revealed between the different nosologic subgroups in the respect of in vitro rates of Na-dependent Li countertransport. Results are discussed in the light of clinical and pharmacogenetic aspects.

Bipolar Disorder↗
PubMed1979

Cell-to-cell contacts in primary cultures of dissociated chicken embryonic brain.

The fine structure of intercellular contacts was studied in primary cultures prepared from chicken embryonic brain. Desmosomes were frequently seen between the glial cells. Synaptic contacts were observed among neuronal cell bodies and neural processes after 8 days in vitro. Gap junctions were revealed between glial elements suggesting a functional role in direct cell communication and providing a morphological basis for previous observations on potassium transport in cultures of dissociated brain cells.

Animals↗
PubMed1979

Effects of lithium on morphological characteristics of dissociated brain cells in culture.

Lithium chloride was added in 5 and 10 mM concentrations for different periods of exposition time to dissociated cultures obtained from chicken embryonic brain. When supplementing lithium at day 1 in vitro for five days, a dose-dependent decrease in total protein was observed in the cultures as compared to the sodium-treated controls. Profound reduction was revealed in the length of neuronal processes and in the number of neuronal cell bodies by phase contrast microscopy and by morphometric means. After exposition of lithium in 10 mM concentration for 48 h, beside a slight decrease in number of perikaryons, a marked reduction in process length of neural elements was observed in the 6-day-old tissue cultures. Ultrastructurally, swollen and degenerating nerve processes have been found after lithium treatment suggesting a particular sensitivity of these structures to lithium ion.

Animals↗