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J Mourek

Publications and source records attributed to J Mourek.

At least 37 records · Page 2Linked to original sources
PubMed1993

[Fatty acids in the serum of hypotrophic neonates].

Using gas chromatography, Carlo Erba 2531 measurements were performed and the composition of serum fatty acids in 9 hypotrophic human newborns (the mean birth = 2184 g, the mean gestation age = 39 weeks) was evaluated. Fatty acids were detected as methylesters and their levels were compared with fatty acids levels of control healthy neonates born at term (n = 32). In the hypotrophic newborns the content of saturated fatty acids (short and medium-chain in particular) significantly increased, the total amount of polyunsaturated fatty acids (PUFA) series n-3 and n-6 significantly decreased and the proportion of arachidonic acid remained unchanged in comparison with the control group.

Chromatography, Gas↗
PubMed1992

Hypoxia and fatty acids in immature nervous tissue in the rat.

In experiments on 2-day-old rats (Wistar strain, our own breed), we studied the effect of altitude hypoxia (9000 m, 60 min) on the proportion of individual fatty acids in the brain (the cortex+the diencephalon+the cranial third of the mesencephalon). We found that hypoxia significantly altered the proportion of the various fatty acids, with a significant increase in the proportion of group n-3 polyenoic fatty acids at the expense of saturated and monoenoic acids. The results fully confirm the conception that one of the most important mechanisms responsible for the high resistance of new born mammals to oxygen deficiency is the ability of immature nervous tissue to activate, in particular, elongation (the elongation of fatty acids) and/or lipogenetic processes.

Animals↗
PubMed1991

[Changes in the laboratory rat during development after parenteral administration of the herbicide Zeazin S-40. II. Morphologic findings].

Influence of Zeazine herbicide on different tissues during acute, subacute, and chronic stages was examined, when sublethal doses not exceeding the quantity usually used were applied. Structural changes of lung tissue, specially in short and medium interval resulted, comprising circulatory, and partially regressive changes on alveolocapillary membrane level with special tendency to multiplication of collagenous tissue in the long-term stage, without any tendency to chronical lesion and change of the function.

Animals↗
PubMed1991

[The fatty acid spectrum in the serum of mothers and infants after premature delivery].

Using the method of gas chromatography on a Carlo Erba 2531 apparatus in Base's modification, the authors identified serum fatty acids of mothers (n = 23) and premature infants (17 girls and 6 boys). The mean birth weight was 2224.3 (800-2650 g), the mean gestation age 34 weeks (28-37 weeks). The fatty acid levels were compared with fatty acid levels of control mothers (n = 7) and control healthy neonates born at term (n = 15). Individual fatty acids were expressed as the ratio in the total volume of fatty acids (100%). The neonates and their mothers were divided into three groups. The most numerous group (n = 12) are mothers who lost the amniotic fluid prematurely (6 hours-12 days), mothers under the influence of Partusisten (n = 10); the third group is formed by mothers treated with ATB (n = 8). In these groups the authors assessed, as compared with controls, the rise of the saturated fatty acid ratio, in particular short-chain fatty acids. The greatest increase was recorded in mothers and children under the influence of Partusisten. The ratio of mono- and polyunsaturated n-6 fatty acids was not altered in the infants, there was, however, a marked reduction of the n-3 fatty acid ratio which are known to play an important role in the regulation of immune responses and to have an anti-inflammatory effect; they are also important for the development of the CNS and retina.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatty Acids↗
PubMed1991

[The effect of intraperitoneal administration of adrenaline on ascorbic acid levels in the brain, adrenal glands and blood in rats of various ages].

Male and female rats (Wistar strain), 5 days old and full grown rats (cca90-120 days) were used for experiments where the authors investigated the effect of adrenaline SPOFA, 0.15 mg/kg body weight administered by the i.p. route, on the ascorbic acid content in the cerebral cortex, in the mesencephalon, cerebellum and medulla oblongata, as well as in the adrenals and plasma. Ascorbic acid was assessed by Roe and Kuether's method (19). The control group was formed by intact rats or a group where saline in analogous amounts (volume) was administered by the i.p. route. Tissues and plasma were processed 30 min. after administration of adrenaline (saline). The method of processing and collection of tissue specimens was described repeatedly in the past (10, 16). It was revealed that 5-day old rats regardless of sex have after administration of saline or adrenaline a higher ascorbic acid concentration in the brain (more frequently significant changes were found in males-incl. plasma). The same applies to the group of full grown males. In full grown females there is usually a decline of the ascorbic acid concentration in the brain (injection and administration of saline is more effective than adrenaline). In full grown rats concurrently a marked rise of the plasma concentration of ascorbic acid occurs.

Adrenal Glands↗
PubMed1990

[The effect of the pH environment and reduced ATP supply on ATPase activity in the brain of young and adult rats].

On five-day-old and adult Wistar rats (of both sexes) experiments were made where the influence of the pH of the medium was assessed as well as that of a lower ATP supply on the activity of (Na(+)-K+) and Mg++ dependent ATPases (E.C.3.6.1.3.) isolated from tissue of the cerebral cortex and possibly the medulla oblongata. The enzyme activity is expressed in mumol.l-1 of released Pi (minute/mg protein). It was found that the drop of pH of the incubation medium (adjusted with HCl) to 7.0 and 6.4 (as compared with pH 7.4 in control measurements) did not cause in 5-day-old rats a significant change in the activity of ouabain sensitive ATPase of the cerebral cortex or medulla oblongata, while in adult rats a marked reduction was observed. At pH 6.4 in adult rats a greater drop of the activity in the cerebral cortex than in tissue of the medulla oblongata was demonstrated. Equally resistant was also ouabain sensitive ATPase in 5-day old rats against the ATP concentration of the medium; even a drop by 50% (as compared with control values) did not cause a significant reduction of activity, while in adult rats a significant drop was observed. In ouabain sensitive ATPase the position is different. In 5-day-old rats a lower pH reduces its activity to an equal extent for pH 7.0 and pH 6.4. In adult rats the activity is also reduced, the reduction being the more marked the more acid the pH of the medium (cerebral cortex).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1990

Proportion of individual fatty acids in the non-esterified (free) fatty acid (FFA) fraction in the serum of laboratory rats of different ages.

In experiments on Wistar strain rats of both sexes, aged 5, 10 and 14 days and adult (90-120 days), of their own breed, the authors determined the quantitative proportion of individual fatty acids in the serum free non-esterified fatty acid (FFA) fraction, using mixed blood (obtained by decapitation) and the titration method of Trout et al. (1960). The proportion of the individual fatty acids was then determined in this fraction by gas chromatography (Base 1978) and their concentration (in mumol.1-1) was determined by simple calculation from the relative chromatogram data. Animals in the first three age groups were killed in the morning, directly from the nest; in adult rats the FFA fraction was measured after a 20 h fast. It was demonstrated that the increase in the proportion of monoenoic acids was highly statistically significant (about fivefold) during ontogenesis and that there was also a marked increase in the quantitative expression of polyenic acids, especially in group (n-6). The n-6/n-3 acid index in the FFA fraction altered during maturation (despite some fluctuation it basically rose from 4.3 in 5-day-old young to 10.0 in adult rats). It was further demonstrated that the concentration of fatty acids with a very short chain fell significantly during development, so that C 8:0, for example, could be detected only in the first two age groups, but not in 14-day-old and adult rats. The concentration of the saturated fatty acids C 15:0 to C 18:0 in the serum FFA fraction showed a statistically significant increase, while the index expressing the ratio of saturated to unsaturated fatty acids displayed a downward trend during development.

Aging↗
PubMed1990

Influence of age, sex and hypoxia on plasma dopamine-beta-hydroxylase activity in the rat.

Using rats (Wistar strain) of our own breed, we studied dopamine-beta-hydroxylase (E.C. 1.14.17.1) (DBH) activity in the plasma of animals of different ages (in correlation to sex) under normal conditions and after exposure to altitude hypoxia (corresponding to 7000 or 9000 m and lasting 20 min). The enzyme was determined by the method of Kato et al. (1974). We found that the given plasma enzyme activity was significantly higher in females than in males, throughout the whole life-span. In addition, we found that minimum activity was reached on about the 14th and 21st day of postnatal life and again on the 40th day, while maximum activity was recorded at the ages of 5, 30 and 35 days and in adult rats. In adult animals (males and females), exposure to altitude hypoxia was followed by a statistically significant increase in plasma DBH activity, which was much more pronounced in females than in males. In males, 240 min after terminating hypoxia plasma DBH activity had returned to normal, but in females it was still significantly raised; after 48 h, plasma DBH activity in females was identical to the activity before exposure to hypoxia. In rats aged 5 and 35 days, hypoxia evoked a fluctuating response. A decrease in activity immediately after terminating hypoxia was followed at 60 min by a return to normal, but at 240 min there was again a significant decrease. In 21-day-old rats, hypoxia did not induce any significant change in plasma DBH activity (the initial activity level in this group was very low).

Aging↗
PubMed1990

[The effect of repeated fasting on the ratio of individual fatty acids in the brain and blood of rats of various ages].

In locally bred, 5-day old and full grown rats, the authors conducted experiments where they investigated the influence of repeated fasting (3 X 18 hours food deprivation on three consecutive days) on a wide spectrum of fatty acids in the cerebral cortex, medulla oblongata and serum. The fatty acids were assessed as methyl esters by gas chromatography, as described in previous work (1, 13, 14, 17). In 5-day old rats after repeated fasting an evident decline in the ratio of saturated fatty acids in serum was recorded; at the same time the ratio of arachidonic acid increased markedly and in the cerebral cortex there was a significant drop of the palmitic acid participation. In adult rats 16 statistically significant changes took place (treble as compared with the 5-day old rats). The large number of significant changes pertained to 18 carbon fatty acid (a rise in all instances in the brain; the ratio of 18:3n-6 in plasma declined significantly). In the serum of adult rats the ratio of arachidonic acid increased also. The authors discuss possible reasons of the described changes.

Aging↗
PubMed1990

[Lactate dehydrogenase and malate dehydrogenase activity in the glial and neuronal fractions of the brain tissue in rats of various ages].

The authors investigated in Wistar strain rats of both sexes aged 10 days and in adult rats (aged 90 days) the activity of lactic dehydrogenase (E.C.1.1.1.27) and malic dehydrogenase (E.C.1.1.1.37) in the neuronal and glial fraction of the cerebral cortex. They found that during maturation the LDH activity declines in the neuronal fraction in a significant way (expressed per mg protein). The LDH activity in the neuronal fraction is always significantly higher than in the glial fraction. The G/N index declines slightly during development (from 0.30 to 0.23). In malic dehydrogenase the authors found also a decline of this activity in neuronal tissue during maturation, while in the glial fraction the activity of this enzyme does not change significantly. The G/N index increased as a result of the described developmental changes from 0.33 in 10-day-old rats to 0.55 in adult ones. The authors used for the isolation of the neuronal and glial fraction the method described by Lisý. LDH and MDH were estimated by previously described methods.

Aging↗
PubMed1990

[The effect of one-time and repeated starvation on dopamine beta-hydroxylase serum activity in rats of various ages].

The authors used for experiments Wistar strain rats, 5 days old and adult rats, and investigated the activity of plasma dopamine-beta-hydroxylase after exposing the rats to a single 24-hour or repeated 3 X 18-hour fast and fluid deprivation on three consecutive days. They found that in both age groups, in males as well as females, both mentioned types of nutritional stress (deprivation) led to a marked reduction of activity of the plasma level of the mentioned enzyme. This reduction was in both types of fasting roughly equal when expressed in absolute or relative figures. The enzyme activity was assessed by a method described by Kato (4) and is expressed in nmol/l ml plasma/min. The statistical evaluation was made by the Biocybernetic department of the Institute of Physiology, Faculty of General Medicine, Charles University, Prague.

Animals↗
PubMed1990

[Acute changes in the body of laboratory rats during development after the parenteral administration of the herbicide Zeazin S-40. I. Determination of LD50 and other biochemical findings].

On laboratory rats of different age the effect of the acute intraperitoneal administration of the herbicide Zeazin S-40, 570 mg.kg-1 was investigated. The dose was derived after assessment of LD50 i. p. It was revealed that this substance causes during the first hour after introduction into the organism a response in the internal environment manifested among others by changes in the serum levels of glucose, lactate and triacylglycerols.

Aging↗
PubMed1989

pH, pCO2 and NADP changes during aerobic and anaerobic incubation of the brain cortex of young and adult rats.

Wistar rats of both sexes, aged 5 and 90-110 days, bred in the author's department, were used for experiments in which pH, pCO2 and NADP changes induced by incubating brain cortex homogenate (30 min at 37 degrees C) under aerobic and anaerobic conditions were studied. The medium was Sörensen's buffer solution, with succinate as substrate. NADP was assayed by determining glucose-6-phosphate dehydrogenase activity, which is NADP-dependent. The pH and pCO2 were determined with an ABL-2 radiometer (Denmark). The NADP extinction curves showed that the adult rat cortex, with or without substrate, always contained significantly less NADP under anaerobic conditions (the amount of its reduced form increased). In 5-day-old rats, the course of changes in the extinction curves was completely analogous to that for adult rats if the tissue was incubated without substrate; in the presence of substrate, the amount of the oxidized form, i.e. of NADP, decreased and there was no difference between the course of extinction changes under anaerobic and aerobic conditions. Similarly, the pH fell significantly less in 5-day-old rats during anaerobic incubation than in adult rats and was practically no different from the pH changes found during aerobic incubation. In addition, we found that the increase in pCO2 during anaerobic incubation of the brain cortex of 5-day-old rats was very small (also compared with aerobic conditions) whereas the increase in pCO2 under aerobic and anaerobic conditions in adult rats was the same.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerobiosis↗
PubMed1989

[The effect of single and intermittent fasting on cholesterolemia in rats of various ages].

Experiments studying the influence of single and repeated fasting on cholesterolaemia were performed in rats of both sexes and of our own breed (Wistar) aged 5, 10, 14 and 21 days of postnatal life and in adult rats. Cholesterol was determined by means of Lachema (CSSR) tests. The single fasting was realized in such way that one half of standard litter was separated from mother and nest for a period of 24 hours. Adult rats did not receive an appropriate diet for the same period. The repeated fasting was carried out as follows: in three successive days half of the litter was separated from mother for a period of 18 hours. For the remaining 6 hours the rats were returned to mother into the nest. Isolation was in both cases performed under optimal thermal conditions. Blood was taken by decapitation. Changes in total cholesterolaemia during ontogenesis (maximum up to 14 days of postnatal life) were confirmed. Fasting was found out to cause a significant decrease in cholesterolaemia in the first three age categories and in adult rats. In rats aged 21 days neither single nor repeated fasting caused a significant change in plasma cholesterol contents. In the first three age groups repeated fasting has a demonstrably higher effect, i.e. the decrease in cholesterolaemia is higher after this type of fasting than after the single one. The results are compared with our previous studies concerning the influence of fasting on the development of organism.

Aging↗
PubMed1989

[Response of the immature brain to changes in the internal and external environment. (30 years' neuro-ontology research at the Physiology Institute)].

The authors summarize some original results obtained in long-term neuroontogenetic research. Substrate variability of immature CNS tissue, its capacity of ketone bodies utilization are described and basic developmental changes in the composition of amino acids, fatty acids and key enzymes in brain are established. Analysis of immature CNS adaptability and plasticity, especially in relation to hypoxic load is presented. On the contrary the results indicating very low resistance of newborn mammal to insufficient nutrition and its far-reaching consequences concerning regulations and functional capacities are presented.

Adaptation, Physiological↗
PubMed1988

Arachidonic acid-induced inhibition of (Na+K+)-stimulated ATPase in the cerebral cortex and medulla oblongata of young and adult rats.

The effect of arachidonic acid in 5.10(-4) and 5.10(-5) mol.l-1 concentration (as the Na salt, SIGMA) on ouabain-sensitive ATPase (E. C. 3.6.1.3) activity was studied in the cerebral cortex and medulla oblongata of 5-day-old and adult rats. In adult rats, arachidonic acid significantly inhibited ouabain-sensitive ATPase activity in both the cerebral cortex and the medulla oblongata. In 5-day-old rats, only the higher concentration (5.10(-4) mol.l-1) inhibited the enzyme statistically significantly; use of the lower concentration was not followed by any significant changes in Na+-K+-ATPase activity.

Animals↗