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Biomedical subjects

Z Lodin

Publications and source records attributed to Z Lodin.

At least 37 records · Page 2Linked to original sources
PubMed1984

Inhibitory effect of tunicamycin on the adhesivity and aggregation of embryonic brain cells.

Tunicamycin (TM) - (0.1, 1.0 and 10 micrograms/ml) inhibits insignificantly the adhesivity of embryonic mice brain cells during the first 120 min of incubation. The effect is not dose dependent. The concentration of 10 micrograms/ml added at the onset of experiments has a drastic effect during the time period in which cell regeneration, cell movement and formation of aggregates occurs. Up to the 5th day in vitro (DIV), aggregation is completely inhibited and disrupted parts of cells are mostly present in the medium. The concentration of 1 microgram/ml is less effective, and 0.1 microgram/ml is practically without effect. EM analysis shows that tunicamycin (10 micrograms and 1 microgram/ml) diminish the regeneration and integrity of plasmatic membranes, 10 micrograms/ml of tunicamycin destroys cytoplasmatic organelles which is probably the cause of the decline of cellular regeneration and of aggregate formation. Tunicamycin (10 micrograms/ml), if added to the already formed aggregates evokes their disintegration and lower doses (1 microgram/ml) liberated cells from aggregates into the medium.

Animals↗
PubMed1983

Gamma-glutamyl transpeptidase activity in isolated cells and in various regions of the mouse brain during early development and aging.

Differences in the distribution of gamma-glutamyl transpeptidase (GGT) activity during early and late postnatal development of the mouse brain were studied at the cellular and regional level. From the 7th to the 25th day of brain development, GGT activity rose evenly in the neuronal perikarya, glial cells and in the neuropil. At 25 days and 5 weeks of age, a 1.5-fold enrichment was observed in nerve cell bodies and in neuroglia as compared with the neuropil and the original cell suspension. During the same period, an abrupt increase in GGT activity was observed in brain capillaries, and between the 10th day and the 5th week, this was 1.5-5 times higher than the enzyme activity in cellular elements and in the neuropil. This increase in enzyme activity in brain capillaries continued up to the age of 12 months, when it was succeeded by a decrease in GGT activity to the level found at 3 months. GGT activity in the choroid plexi rose significantly (more than double) between the age of 5 weeks and 18 months and was a whole order higher than GGT activity in 10 other regions of the mouse brain, whose development displayed no pronounced changes in the activity of the enzyme. A single dose of dexamethasone, or adrenalectomy, were used to demonstrate any participation by steroid hormones in the regulation of GGT activity in the brain tissue. Of the two techniques, only adrenalectomy led to a statistically significant decrease in activity in brain and liver tissue, while the apparent increase in GGT activity after a single dose of dexamethasone was not statistically significant.

Aging↗
PubMed1983

Ultrastructural and protein synthetic changes in embryonic brain: cells aggregated at 0 degree C.

Cells dissociated from brains of 16 to 18 day-old mice embrya were rotated at 37 degrees C and 0 degree C for 7--8 days. While cells aggregated at 37 degrees C formed compact aggregates, cells aggregated at 0 degree C were found in clusters or were randomly distributed. Cells aggregated in the cold did not differ markedly from the controls in their ultrastructural organisation till the 2--3 day in vitro (DIV). Later, significant structural changes, such as distention of cytoplasmic membranes, destruction of mitochondrial membranes, disappearance of ribosomes, shrinkage of nuclei and disturbance of cytoplasmic membranes were apparent. On the 6--7 DIV, groups of cells were separated by a distance of 100 nm and more, and large parts of their cytoplasm disappeared and outside cell perikarya fragments of membranes appeared forming dense debris. However, even at this period some cells were found which did not show signs of degeneration. Protein synthetic activity in aggregated cells increased linearly at 37 degrees C till 7 DIV, whereas in cells aggregated at 0 degree C an inhibition of about 34% was found at 4 DIV and at 7 DIV the curve of 14C leucine incorporation declined almost to zero. It is thus evident that cells aggregated at 0 degree C maintain an almost normal ultrastructural pattern during the first days of cultivation and only protein synthetic activity is lowered. Cellular membranes, damaged during the dissociation partly regenerated even at 0 degrees C and membraneous contacts were formed between several cells.

Animals↗
PubMed1983

Enzyme activity pattern in developing mouse brain in situ in embryonic brain aggregated cells at 37 degrees C and 0 degree C.

In aggregates of nervous tissue, cultivated for 1--7 days at 0 degree C and 37 degrees C, respectively, the activities of seven enzymes of energy liberating metabolism were estimated, in order to evaluate their metabolic "profiles" and changes during cultivation. The enzymes used as markers of different pathways of energy liberation from substrates were: lactate dehydrogenase - LDH - (EC 1.1.1.27), triose-3-phosphate dehydrogenase - TPDH - (EC 1.2.1.12), glycerol-3-phosphate dehydrogenase - GPDH - (EC 1.1.1.8), hexokinase - HK - (EC 2.7.1.1.), malate:NAD dehydrogenase - MDH - (EC 1.1.1.37), citrate synthase - CS - (EC 4.1.3.7), and 3-hydroxyacetyl CoA dehydrogenase - HOADH - (EC 1.1.1.35). During the cultivation, some changes in the metabolic "profiles" were observed. Although some of these changes as well as the differences between the cultivation at 0 degree C and 37 degrees C, were statistically significant, they were not greater than the variations between different samples of any tissue taken at different times. They were not, therefore considered to be of major significance. However, all the aggregates exhibited "profiles" characteristic for the nervous tissue, with relatively very high activity of HK, high activity of MDH and CS (carbohydrate breakdown) and low activity of GPDH and HOADH (lipid catabolism).

Animals↗
PubMed1981

Adhesion of dissociated mouse embryonic brain cells. A new method of quantitative evaluation.

The adhesion of mouse embryonic brain cells was measured in a rotating chamber. A method is proposed for quantitative evaluation of adhesion kinetics. Dissociated cells were incubated in a planparallel chamber and pictures were taken between time 0-120 min. Film negatives were evaluated by computer--controlled scanning. Ten thousand individual data area obtained from one frame and 1,000 levels of absorbency are distinguished. A method is described which allows the discrimination of area, density and the shape of adhering cells. The influence of the dissociation procedure on cellular adhesion was studied. Short trypsinisation (0.025% trypsin for 5 min) followed by sieving was most favourable for adhesion. Mechanical sieving and dissociation with EGTA (Ca2+ chelator) gave less satisfactory results. Significantly diminished adhesion was observed after prolonged trypsinisation. If cells were incubated in media lacking Ca2+, adhesion was significantly inhibited. The kinetics of adhesion follows the curve of flocculation kinetics independently of the dissociation procedure and composition of the medium.

Animals↗
PubMed1981

Reaggregation of human, chick, and human embryonic brain cells. Factors influencing the formation of a histiotypic unit.

1. Aggregation of embryo human, mouse, and chick brain cells was studied. The optimum age interval of donors from different species was determined. 2. The significance of different dissociation procedures (mild trypsinisation followed by sieving, trypsinisation + DNA digestion, mechanical dissociation in 1 or 2 steps, and Ca2+ chelation by EGTA) for the rate of aggregation was estimated. A significant reduction of aggregation was observed after one step mechanical dissociation. Nonspecific adhesion of cells on DNA molecules was found only during the first stages of aggregation. 3. The curve of aggregation kinetics follows the curve of floculation kinetics. 90% free cells disappear from the medium after 2 h of aggregation and a large number of microaggregates are formed which condense after 20 to 24 h into compact aggregates. The time course of aggregation was similar for all cells dissociated by different means. Small differences in the rate of aggregation, caused by dissociation procedures, were apparent only during the first stages of aggregation. 4. The histiotypic unit formed by aggregation of human, mouse, and chick embryo brain cells exhibits some common and some specific features. During aggregation a multiple structural reconstruction takes place and a limited number of cells are exchanged or sorted out from aggregates into the medium. 5. The structural organisation of aggregates from differently dissociated cells differs in several aspects. This indicates that membrane surface structures are influenced differently by dissociation and behave differently during distinct stages of aggregation.

Animals↗
PubMed1980

In vitro K+-effect on ATP and phosphocreatine levels and on Na+ K+-atpase activity of mouse brain cells.

Cell suspensions were prepared form mouse brain cortices. Cells were incubated in a medium also containing 10 mmol.l-1 glucose and either 5 mmol l-1 K+ or 50 mmol.l-1 K+ concentration. In order to standardize individual experiments, the biuret reaction was modified for rapid determination of the protein in cell suspensions. The cellular reserves of energy-rich phosphates were determined in the course of 60 min of cell incubation with 5 mmol.l-1 K+ and following 30 min incubation of cells with 50 mmol.l-1 K+. The level of ATP was significantly elevated after 10-60 min of incubation with low K+, from 0.58 to 0.78 micromoles per 100 mg protein; the creatine phosphate content during the same interval was in the range 1.27-1.44 micromoles per 100 mg protein. A significant decrease of energy reserves in cells was observed if the extracellular concentration of K+ was increased. After 10 and 30 min of incubation, a decrease by 36.2% and 38.5% for creatine phosphate and 34.6% and 44.9% for ATP was found, respectively. Na+ K+-ATPase activity of cells incubated for 60 min with 5 mmol.l-1 K+ was expressed as 4.99 micromoles of liberated Pi per 100 mg protein.1 h. Enzyme activity was stimulated with 50 mmol.l-1 K+ by 24.3% and 25.7% after 10 and 30 min of cell incubation respectively. Stimulation of Na+ K+-ATPase activity of brain cortex cells was directly dependent on the actual presence of stimulating 50 mmol.l-1 K+ concentration.

Adenosine Triphosphatases↗
PubMed1979

Constancy and variability in the content of DNA in cerebellar Purkinje cell nuclei. A cytophotometric study.

A cytophotometric study of DNA content in Purkinje cells of the cerebellum of rats, cats, chicken and humans (Feulgen staining) revealed that in a certain number of cells the amount of NDA ranged between the diploid and tetraploid level (H2C cells). The incidence of H2C Purkinje cells varied among the species studied. In rats, which were studied most thoroughly, these cells amounted on average to 3%. In some rats, as well as in some cats and chickens H2C Purkinje cells were entirely absent. In the group of animals possesing H2C Purkinje cells, great interindividual differences were observed. In rats for instance, the incidence of these cells varied from 1 to 23 per cent. Topographic analyses carried out in rat and human cerebellum revealed that H2C Purkinje cells occurred more frequently in the hemispheres than in the vermis. No significant differences were found in the number of H2C Purkinje cells in healthy and Kilham-DNA-virus infected rats. Densitometric analysis of the distribution of nuclear chromatin showed that H2C Purkinje cells were richer in condensed chromatin, especially in the region of the nucleolus, which apparently contains the hyperploid surplus of DNA. It is proposed that the phenomenon of DNA hyperdiploidy arises as a result of either incomplete S-phase in some immature Purkinje cell precursors or the amplification of some DNA sequences particularly those localized in the nucleolar region.

Aged↗
PubMed1979

Regional distribution of membrane-bound gamma-glutamyl transpeptidase activity in mouse brain. Comparison with rabbit brain.

Activity of membrane-bound gamma-glutamyl transpeptidase (gamma-GTP) was examined in various regions of mouse brain, in capillaries of the cerebral cortex and in telencephalic choroid plexuses. The level of activity in the capillaries was double and that of the choroid plexus nine times that of the gamma-GTP activity found in the brain, septum, hippocampus, hypothalamus, thalamus, cerebellum, frontal cortex, pons, medulla oblongata, and amygdala. Histochemically the gamma-GTP activity was demonstrated in the surface membranes of choroidal cells and in the endothelium of small capillaries. The activities of gamma-GTP of cerebral cortex, choroid plexus, and capillaries from rabbit were 5--17 times greater than those from corresponding areas of mouse brain. While 30 mM methionine stimulated (in vitro) the enzyme from mouse brain, no such effect was observed with the enzyme activity from rabbit brain. The gamma-GTP activity from the capillaries of cerebral cortex of both mouse and rabbit was not affected by the presence of methionine. These findings suggest existence of differences in the specificity of gamma-GTP activity in these two species.

Amygdala↗
PubMed1979

The effect of dibutyryl cyclic AMP on cultivated glial cells from corpus callosum of 30-day-old rats.

1) Fragments of corpus callosum of 30-day-old rats were cultivated in Rose chambers. Mature astrocytes and predominantly differentiated oligodendroglial cells are present in the corpus callosum of rats at this age. 2) In vitro, astrocytes dedifferentiated into epithelial--like flattened cells, which highly adhered to the surface. Cells exhibited signs of phagocytosis, and their ultrastructure differed from differentiated cells, especially by the absence of microtubules and microfilaments. 3) After dibutyryl cyclic AMP (db-c-AMP) application, epithelial--like cells became rounded and multipolar. Cells were less liable to adhere to the surface. Bundles of microfilaments and microtubules appeared in cell perikarya and their processes. 3--4 hour after application, the morphological changes were well developed and disappeared after 24--48 hours. 4) It is being suggested that the increased intracellular concentration of db-c-AMP induced the formation of microfilamentous structures. The formation of the cyto-skeleton has a direct influence on the shape of cells and appearance of processes and cell adhesivity. 5) These results have demonstrated the high structural plasticity of mature astrocytes, their dedifferentiation in vitro and convertion into mature cells after db-c-AMP application.

Animals↗
PubMed1978

Nuclear pore complexes in cells of the developing mouse cerebral cortex.

The nuclear pore complexes of cells of the superficial layers of the cerebral cortex of mice were studied by freeze-etch technique. The nuclear membrane was found to be randomly penetrated by typical octagonal pore complexes in all age groups studied. The density of pores (per micron2) amounted to 7.8, 14.0, 17.0, 18.1 and 14.1 on the 18th to 20th embryonic and the 8th, 15th, 50th and 180th postnatal day respectively. The total number of pores per nucleus increases 5.2 times from the 18th to 20th prenatal to the 15th postnatal day and then decreases toward the 180th postnatal day (1257, 6582 and 3385 pores per nucleus respectively). The density of pores in cells of brain cortex, found in young adult mice is relatively high, if compared with other cell types.

Animals↗
PubMed1978

Structure and ultrastructure of cultivated glial cells from Corpus callosum.

1. Explants and dissociated cells from Corpus callosum (c. c.) of rats and rabbits were cultivated in Petri dishes and Rose chambers. 2. Different types of glial cells were found in the cultivated Corpus callosum (c. c.) explanted from 12 days old rats: a) adendritic glial cells, typical for migrating oligodendroglial cells, b)-migrating large, nondifferentiated astrocytes with pronounced phagocytosing activity, c) macro- and microglial cells which differentiated during cultivation. 3. The population of differentiated glial cells is mostly composed of oligodendroglia, less of astrocytes and microglial cells are rare. 4. Differentiation of dissociated cells from c. c. in homogenous and mixed population was studied. The appearance of first processes of macroglial cells is postponed to 6 to 10 days of cultivation. No substantial difference was observed between homogenous and mixed population. A higher incidence of macrophages was observed in the later. 5. Glial cells differentiate surrounded by degenerated nerve fibers and myelin, exhibiting phagocytoses and cleaning reaction.

Animals↗
PubMed1978

Differentiation of corpus callosum glial cells and factors influencing their maturation in vitro.

1. Explants of Corpus callosum (c. c.) from 12-day-old rats were cultivated under different experimental conditions. 2. Migration and differentiation is activated by the presence of neighbouring explants, toward which glial cells predominantly migrate. Glial cells migrate if closely adhering to the supporting collagen and the process of differentiation is enhanced by presence of underlying cell layers. 3. Migratory activity of glial cells decreases and is delayed with age of donors. Migrating cells have a similar appearance as in cultures from 12 days old donors. The presence of immature types of glial cells in c. c. of adult animals was proved. 4. Glucose was found to be an adequate metabolical substrate, utilisation of glucose being lower than in cultivated neurons. In the absence of glucose or serum in the medium, neither migration nor differentiation of glial cells was observed. 5. The addition of embryonal extract and embryonic brain extract enhanced only initial stages of cell migration and differentiation.

Age Factors↗
PubMed1978

K+--induced changes of oxygen uptake by neuronal enriched and glial enriched fractions from mouse brain cortex.

Neuronal and glial enriched fractions were incubated in a medium with 10mM pyruvate, 5mM fumarate and 0.9mM 5'-AMP and the effect of increased external K+ concentrations was studied upon oxygen uptake. A concentration of 65 mM K+ had a different effect on the oxygen consumption of glial and neuronal perikarya. The rate of oxygen uptake by glia was stimulated by 52.81% whilst an insignificant decrease of 15.79% occurred in the neurones. The highest rate of oxygen uptake by incubated cells was estimated in the presence of the substrate system containing pyruvate, fumarate and 5'-AMP. The significance of components in the substrate system for a high rate of oxygen uptake by cells was also tested with 6.2 mM K+ and 65 mM K+.

Animals↗