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Biomedical subjects

J Mourek

Publications and source records attributed to J Mourek.

At least 19 recordsLinked to original sources
PubMed2005

Lipoperoxidative activities in the cerebral cortex and medulla oblongata, related to age, sex, oxygen deficiency and short-term fasting.

In albino rats (Wistar), aged 10 and 14-days of postnatal life, experiments were performed, in which the intensity of lipoperoxidative processes in cerebral cortex and medulla oblongata in four experimental series was measured and compared: a) between females and males (control group); b) between females and males exposed to the hypobaric hypoxia (corresponding to the altitude of 7000 m and lasting 20 minutes); c) between females and males exposed to the short-term starvation (for 24 h between the day 5th and 6th of postnatal life); d) between females and males exposed to the combination of short-term starvation and hypobaric hypoxia. No sex-dependent differences in control measurements could be detected. The hypobaric hypoxia evokes significantly greater increase in lipoperoxidative processes in brain tissue of males as compared with females. The short-term starvation affected more the oxygen radicals production in the brain of females. Finally--the short-term starvation and the subsequent hypoxic stress did not evoke the sex-dependent differences in the brain of 10-day-old rats; in 14-day-old females the higher values in brain cortex, in males higher values in medulla oblongata were established. The different sensitiveness to mentioned stressors in males (more sensitive to oxygen deficiency) and in females (more sensitive to nutritional deficiency) was described.

Aging↗
PubMed2004

[Effect of hypothermia on lactate dehydrogenase activity in blood and the cerebral cortex in 14-day-old and adult laboratory rats].

OBJECTIVE: In the following study, possible protective effect of hypothermia (of various degree) on brain cortex metabolic activity in very young animals and adult rats was examined. DESIGN: Experimental study. SETTING: Institute of Physiology, 1st Med. Faculty, Charles University, Prague, Czech Republic. METHODS: Homogenates of brain cortex of 14-day-old and adult rats and simultaneously blood serum were examined for lactate-dehydrogenase activity (LDH), [E.C. 1.1.1.27]. Three variously tempered incubation media (38 degrees C = control values, 30 degrees C = mild hypothermia, 22 degrees C = strong hypothermia) were checked. Also the adult rats (90-120 days) were examined (in the same arrangement). RESULTS: The LDH activity in the blood serum of 14-day-old rats under hypothermic condition was unchanged as compared with control values. In their brain cortex the hypothermia evokes a significant changes in LDH activity (mukat/l). In adult rats the results are different: no significant changes in LDH activity in the brain cortex under hypothermic condition were found, but significant drop in mentioned enzyme activity in the blood serum was established. Finally: in young animals the starting LDH activity in the blood serum as well as in the brain cortex was always significantly higher as compared with values found in adult animals. CONCLUSION: The starting higher LDH activity in the blood serum as well as in the brain cortex in young rats (as compared with adults) and the different feature of LDH changes under hypothermic conditions are considered and discussed especially with the possibility of protective action of hypothermia in hypoxic and asphyxic newborns.

Aging↗
PubMed2004

[The effect of posthypoxic hypothermia for lactate dehydrogenase activity in brain cortex and blood serum of 14-days-old rats].

OBJECTIVE: The effect of various degrees of hypobaric hypoxia and consequent hypothermia on lactate dehydrogenase (E.C.1.1.1.27) activity in blood serum and brain cortex in 14 day-old rats was investigated. DESIGN: Experimental study. SETTING: Institute of Physiology, 1st Med. Faculty, Charles University, Prague. METHODS: 14 day-old rats (Wistar of our own breed) were exposed to mild hypobaric hypoxia (corresponding to altitude of 7000 m, pO2 = 8.6 kPa, BP = 41.2 kPa, lasting 20 min) or strong hypobaric hypoxia (corresponding to altitude of 9000 m, pO2 = 6.4 kPa, BP = 30.7 kPa, lasting 30 min). Just after hypoxic stress the animals were killed by decapitation and on cooled block the grey cortical matter was removed. Blood serum samples as well as brain cortex homogenates were immediately incubated in three variously tempered media (38 degrees Celsius = control values, 30 degrees Celsius and 22 degrees Celsius = hypothermic conditions). The incubation was over (30 min.), and the lactate dehydrogenase (LDH) activity was followed using the Lachema test. RESULTS: The LDH activity was influenced by mild hypobaric hypoxia (7000 m) neither in blood serum nor in brain cortex. Also the values of LDH activities registered in normo or in hypothermic conditions were not different as compared with control values. The strong hypoxia (9000 m) evokes in brain cortex homogenates simultaneously with normothermia and posthypoxic hypothermia (30 degrees Celsius) significant increase of LDH activity. In blood serum the strong hypoxia increased the LDH activity; in subsequent hypothermic condition (22 degrees Celsius) the LDH activity was more lowered. CONCLUSION: The LDH activity in brain cortex as well as in blood serum of young rats (Wistar) seems to be resistent to mild hypoxia (7000 m) as well to hypothermic conditions. The strong hypoxia (9000 m) evokes quite different responses: in brain cortex the LDH activities in hypothermic conditions are higher, in blood serum lower as compared with control values (14 day-old rats stressed by hypoxia only). In control measurements the lowering temperature decreases the mentioned enzyme activity in brain cortex; in blood serum no significant differences could be found.

Air Pressure↗
PubMed2004

Plasticity of the brain in neuroontogenesis.

Plasticity is a specific endowment of the nervous system to develop, to react or to adjust to the internal and external 'environmental changes, both in the physiological and pathological conditions. Cumulative evidence has revealed the dynamism of the nervous system, based on the balance between the rigidity and plasticity. Different aspects of neuroplasticity can employ common general cellular mechanism. Effects of plasticity can be either positive or negative changes during the development (evolutional plasticity), after the short-term exposition (reactive plasticity), after the 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, irrespective of a cause, which triggered them, or the brain region where they were accomplished. Activity of neuroplastic processes appears to be especially high in the immature nervous tissue.

Animals↗
PubMed1998

[Gestational diabetes--a model trial. The effect of alloxan diabetes on the spectrum of fatty acids in the blood, liver and brain in laboratory rats].

In alloxan-induced diabetic rats (Wistar, females, age 3-4 months of postnatal life) the large spectrum of fatty acids in blood serum, brain cortex, medulla oblongata and liver was studied. The fatty acids, using gas chromatography, were detected as methyl esters and the methods were published previously (Smídová and al. 1994). Alloxan (Merck) administered i.p., 140 mg/kg body weight, caused immediately elevation (three times) of blood sugar levels. On the 13th day the rats were killed. The results are as follows: a) In blood serum alloxan diabetes of cca two weeks duration caused a significantly increased participation of saturated FA and decreased participation of both polyunsaturated FA (n-3 and n-6). b) In brain cortex no differences between controls and diabetic rats in the indicated groups of FA were found. c) In the medulla oblongata an increased participation of polyunsaturated fatty acids n-6 was established. d) In hepatic tissue the increased participation of saturated FA as well as a decreased participation of FA n-6 was described. Analysing the main groups of FA we found especially in n-3 and n-6 FA several significant changes in single FA (a smaller pool of arachidonic acid in blood serum as well as in liver, decreased participation of docosahexaenoic acid in the brain cortex, etc.). The purpose and possible consequences of such changes are discussed.

Alloxan↗
PubMed1997

[Adrenergic tocolytics--their effects on lipoperoxidation in the brain].

As a sequence of our previous investigations and published results dealing with the inhibitory effect of the BETA-mimetic Tocolyticum (Partusisten) on the blood plasma levels of polyunsaturated fatty acids (n-3), we performed experiments where the possible inducing effect of BETA-mimetic drugs (epinephrine and isoprenaline) on the lipoperoxidative processes in the brain and liver was studied. (Adult rats-females.) Lipoperoxidation was tested by the method of Ohkawa and al. [21] based on changes in malondialdehyde (MDA) production. The intraperitoneal administration of isoprenaline (0.15 mg/kg body weight) increases significantly the MDA production in the cerebral cortex as well as in the medulla oblongata of rats (females-Wistar). Isoprenaline induces a small but significant decrease of MDA in the liver. The intraperitoneal administration of epinephrine (0.15 mg/kg body wight) raises significantly the MDA production in the cerebral cortex as well as in the medulla oblongata. In hepatic tissue changes in MDA levels were not observed. The mentioned data indicate that the decrease of polyunsaturated fatty acids (esp. of n-3 series) in plasma of human newborns and their mothers treated by BETA-mimetic tocolytic drugs (as Partusisten), could be associated with the significant higher lipoperoxidation. The clinical use of such tocolytic drugs has to be discussed also from this point of view.

Adrenergic Agonists↗
PubMed1996

Relationship between birth weight of newborns and unsaturated fatty acid(n-3) proportions in their blood serum.

In a group of 26 preterm newborn infants (gestational age 24-37 weeks, birth weight 560-2800 g) we followed the possible relationship between the birth weight and the proportion of polyunsaturated fatty acids n=3 in the blood serum. The blood samples were taken usually within 24 hours after birth, exceptionally within 48 hours. The newborns as well as their mothers did not receive antibiotics, tocolytics or hormonal therapy. We found a positive correlation between the birth weight and the proportion (expressed in %) of polyenoic fatty acids(n-3) in the blood serum. This relation could be expressed by the regression line (r=0.636, p<0.001, % FA(n-3) = -1.166 + 0.00217 x birth weight in g. The value of Kruskal-Wallis criterion H was 15.158. The importance of such a relationship is discussed.

Birth Weight↗
PubMed1995

[Tocolysis and fatty acids].

To six pregnant female rats Wistar strain the beta-mimetic tocolytic preparation (Partusisten-Boehringer) was administered by the s.c. route on the 19th, 20th and 21st day of pregnancy-0.1 mg per 250 mg body weight. The above dose corresponds to clinical practice and was divided into two parts: half the amount was administered between 8 and 9 a.m., the second half between 1 and 2 p.m. To pregnant controls (mean weight 340 g) saline was administered in an analogous way. On the 22nd day of pregnancy the females with a mean weight of 330 g were sacrificed by decapitation and concurrently with collection of mixed blood the calva was opened and on a cooled block the grey matter of the brain cortex was isolated. From the foetuses pooled blood samples (from 4-5 foetuses) and samples of the CNS were collected. From each foetus 0.5 ml blood was examined. The fatty acid spectrum was assessed by gas chromatography in Base's modification (1978). It was revealed that that administration of the tocolytic to pregnant females affected most the spectrum of unsaturated fatty acids of the n-3 series. In the initial there was a statistically significant increase of linolenic acid C 18:3 n-3 values in the serum as well as in the cerebral cortex as compared with controls. In two other acids, C 18:4 and C 20:4 on the other hand, a marked drop occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Protective effect of carnitine on lipoperoxide formation in rat brain.

Carnitine administration (by intraperitoneal injection) to 21-day-old-rats prevents the increase of thiobarbituric acid-reactive substances (index of lipid peroxidation and free radical damage) induced by 30 min hypobaric hypoxia in four different parts of the brain (cerebral cortex, subcortical structures, medulla oblongata and cerebellum).

Animals↗
PubMed1994

The lipid peroxidation in various parts of the rat brain: effect of age, hypoxia and hyperoxia.

The effect of normobaric oxygen atmosphere on hypoxia-enhanced lipid peroxidation in the brain cortex, subcortical structures, medulla oblongata and in the cerebellum was observed in 7- and 21-day-old and adult rats. The production of free oxygen radicals causing lipid peroxidation was assessed by the method described by Ohkawa et al. (1979). The rats were exposed for 30 min to 100% oxygen atmosphere which significantly stimulated the production of malondialdehyde (MDA) in all the studied regions of the brain in 7- and 21-day-old male rats, and in the brain cortex and subcortical structures of adult males. Higher levels of MDA were found in the brain cortex of 7-day-old female rats only. Reoxygenation with pure oxygen after 30 min hypobaric hypoxia corresponding to 9000 m increased MDA production in all studied parts of the brain on both male and female rats 7- and 21-day-old. In adult rats significantly increased MDA production was only found in the brain cortex of male and female rats and in the subcortical structures of males. The exposition to hypobaric hypoxia followed by reoxygenation by atmospheric air enhanced MDA production in all studied regions of the brain in 7-day-old males and in the cerebellum of females; in 21-day-old rats of both sexes a significant increase of MDA was detected in all parts of the brain. In adult rats were found higher MDA levels in the cerebral cortex of both males and females.

Aging↗
PubMed1993

[Serum fatty acids in premature neonates].

In the past we have published several papers concerning the evolution of large spectrum of fatty acids in the brain or in the blood-serum in rats or in human newborns (and their mothers just after the delivery). Therefore we realized this study: the blood-serum spectrum of fatty acids in the healthy human newborns (n = 32) was compared with the spectrum of fatty acids detected in the blood-serum of human premature neonates (n = 22). The birth-weight in the control group was 3,882, in the premature neonates 2,137 g only. Fatty acids were measured as methylesters (FAME) using the method of gas chromatography and absolutely the same methodological approach as in our previous studies (33, 22, 23). The results were computed by biocybernet. dep. of Physiological institute and the statistics were evaluated by Mann-Whitney U test. It was established that the premature neonates show a distinct greater content (expressed in percentage) of saturated fatty acids and a smaller share of polyenoic FA (PUFA). A further marked difference consists in a significant lower of the n-3 FA and consequently a higher n-6/n-3 index. In premature neonates a significant increase of caprylic acid and arachidonic acid in the blood-serum was detected. The significance of described changes in the participation of single fatty acids in the premature neonates for their maturation, structural evolution especially of the brain cells and for therapy, is discussed.

Fatty Acids↗
PubMed1993

[The spectrum of fatty acids during lactation in women].

The large spectrum of fatty acids (expressed in relative values) was studied in the breast-human milk during the first three weeks of the lactation (3rd, 5th, 10th and 20th day after delivery). All women passed the pregnancy and the delivery without any pathological syndrome and their neonates were found as a healthy and physiological too. No drug dependency was registered. Fatty acids were measured as methyl-esters (FAME) using the method of gas chromatography (1). During the 20 days after delivery and of lactation period, summarising the groups of fatty acid (saturated, monoenoic, PUFA n-3, n-6 and n-9) only few changes could be detected: the increase of the participation of saturated fatty acids of short-medium chain (8:0, 10:0 and 12:0) and of PUFA n-9. Compared with the most administered commercial formula Feminar, the visible differences in the participation of fatty acids were described. Finally: during the lactation we could obtain a large number of significant differences of such individual fatty acids as palmitic acid, arachidonic acid, eicosopentaenoic acid, linoleic acid ect. The possible reasons of such changes during the lactation are discussed and these results are compared with our previous data concerning the fatty acid- spectrum in blood plasma of healthy newborns and preterm or hypoxic infants.

Fatty Acids↗
PubMed1993

Hypoxia and the metabolic behavior of the immature brain.

The immature brain, affected by hypoxia (of certain degree and duration) shows several distinct differences as compared with the mature one. We demonstrated that previous hypoxia does not disturb the aerobic metabolism (in the newborns). The respiratory rate remains the same or its increase is accompanied by the improved coupling processes (the effect of DNP, increased incorporation of P32 into ATP fraction). Hypoxia elevates--at the same time--in the brain tissue of the youngest rats, the proportion of polyenoic n-3 fatty acids. This mechanism (hydrogen sink effect or hydrogen is drained to the synthetic work-elongation of fatty acids) could be decisive factor explaining the high resistance of the mammalian newborns against any lack of oxygen and at the same time their higher capacity for the recovery processes. This fact acquires a further physiological dimension.

Adenosine Triphosphate↗
PubMed1993

Lipid peroxidation in isolated membranes of cerebral cortex, heart and kidney.

The extent of ADP.Fe/NADPH-induced lipid peroxidation measured as production of thiobarbituric acid-reactive substances (TBARS) was determined in isolated membranes from cerebral cortex, heart and kidney of 21-days-old rats. The time course of lipid peroxidation showed higher production of TBARS in cerebral cortex than in heart and kidney. Our data indicate that high level of TBARS production is not due to high activity of NADPH oxidoreductase but due to high content of endogenous lipids in cerebral cortex membranes that could be modified. Higher production of TBARS in cerebral cortex is the result of higher content of lipids in cerebral cortex membranes because NADPH cytochrome c reductase activity in membranes of cerebral cortex is lower than that of heart and kidney.

Adenosine Diphosphate↗
PubMed1993

[Essential fatty acids in neonates at risk and in the mother's milk].

The participation of essential fatty acids and their derivatives in the blood (serum) of physiological healthy neonates (physiological pregnancy, physiological delivery) is compared with the spectrum of essential fatty acids of risk newborns (prematurity, prematurity with the tocolytic therapy and hypotrophic newborns). In the following part the presence and participation of essential fatty acids in the human maternal milk were measured. The milk of healthy mothers, of mothers with preterm delivery (37 week of gestation), of diabetic mothers were mutually compared and finally the values of mentioned essential fatty acids in formula Feminar and in the milk from the bank were established. As a consequence of our observations, they point out the absence or serious deficit of some essential fatty acids in certain groups of risk newborns as well as in the milk of diabetic mothers, of mothers with preterm delivery and in Feminar and Milk-bank. The presented facts--after their opinion--could be well judged as a rational basis for adequate nutritional therapy in risk newborns.

Animals↗