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Biomedical subjects

M Juráni

Publications and source records attributed to M Juráni.

At least 19 recordsLinked to original sources
PubMed2004

Effect of melatonin on neurobehavioral dysfunctions induced by intrauterine hypoxia in rats.

Intrauterine hypoxia associated with oxidative stress represents an important risk factor for development of neurobehavioral dysfunctions. In the present study, we investigated the potential protective effect of melatonin (MEL) on neurobehavioral dysfunctions induced by chronic intrauterine hypoxia in rats by the anticonvulsant drug phenytoin (PHT), which is known by its teratogenic potential. Pregnant female rats (Wistar/DV) were orally treated by PHT (150 mg/kg) from day 7 to 18 of gestation. MEL was dissolved in drinking water (40 microg/ml) and administered from day 0 to 19 of gestation. Neurobehavioral development of offspring was evaluated from birth up to day 90 of postnatal life. The results of the study confirmed the high behavior-teratogenic potential of PHT. Prenatal administration of PHT resulted in delayed neuromotor and reflex development, decreased exploration in the open field, abnormal "circling" and impaired performaces in water maze. Co-administration of MEL failed to have any effect on neurobehavioral dysfunctions induced by PHT treatment. Even administration of MEL alone caused developmental alterations in offspring manifested by accelerated testes descent and delayed onset of negative geotaxia and startle reflex. The results suggest to pay increased attention to MEL concerning its exogenous use during pregnancy.

Analysis of Variance↗
PubMed2002

Cardiovascular system of offsprings of hypertensive rats with defective nitric oxide production.

The question was addressed of how nitric oxide synthase (NO synthase) inhibition-induced hypertension in rat parents would affect the cardiovascular system in their offsprings. Two experimental groups were set up: Group I -- offsprings of parents who had both been administered NO synthase inhibitor L-nitro-arginine methyl ester (L-NAME 40 mg/kg/day) for 5 weeks, the treatment of dams continued till week 12. Group II -- offsprings fed by dams administered L-NAME after delivery only for a period of 4 weeks. Control age-matched offsprings formed the third group. Blood pressure and heart rate in parents and in 3-week-old offsprings were determined noninvasively. In the offsprings, body and heart weight were measured and the heart/body weight ratio (HW/BW) was calculated. The NO synthase activity, and also ornithine decarboxylase activity as a marker of polyamine production, were determined in the heart. The acetylcholine-induced relaxation of aortic rings was also followed. A marked blood pressure increase with a tendency to a decreased heart rate was found in the offsprings of Group I. A significant decrease in heart weight and body weight with a decreased HW/BW ratio indicated cardiac hypotrophy that contrasted with the decrease in NO synthase activity and increase in ornithine decarboxylase activity in the heart. Noteworthy was also the finding of completely preserved relaxation of the aorta to acetylcholine. Offsprings of Group II were similarly characterized by significantly higher blood pressure, a tendency to decreased heart rate, a decrease in heart weight, but not of the HW/BW ratio. The contrasting findings of heart weight decrease on the one hand and NO synthase activity decrease and ornithine decarboxylase increase on the other, were also found in this group. Full relaxation of the aorta to acetylcholine was preserved. It can be concluded that remarkable alterations in the cardiovascular system were found in offsprings of hypertensive NO compromised parents.

Acetylcholine↗
PubMed2001

Developmental changes in thyrotropic and somatotropic effect of TRH in precocial Japanese quail and altricial European starlings.

The thyrotropic and somatotropic effects of thyrotropin releasing hormone (TRH) in precocial Japanese quail (Coturnix japonica) and altricial European starlings (Sturnus vulgaris) during postnatal ontogeny were studied. Concentrations of thyroid hormones (TH) and growth hormone (GH) in the circulation were determined 60 min after the subcutaneous administration of TRH. In quail, TRH caused an increase of triiodothyronine (T(3)) in plasma during the phase of rapid growth, whereas thyroxine (T(4)) concentrations were not affected. In starlings, with a different developmental pattern of TH concentrations, TRH induced an increase of plasma T(3) concentrations on all analyzed days, whereas a significant increase of T(4) occurred on day 1 only. Concentrations of GH were stimulated by TRH in both species. Although growth rate is nearly two times higher in starlings than in quail, differences in the control of the thyrotropic and somatotropic axes do not parallel this difference and tissue sensitivity to other hormonal signals are expected in both developmental strategies.

Animals↗
PubMed1999

Influence of food restriction on dopamine receptor densities, catecholamine concentrations and dopamine turnover in chicken brain.

To investigate further a putative role of dopamine in control of food restriction-induced behavioural stereotypies, chickens were fed during rearing on either a daily restricted ration recommended by a breeding company, twice the recommended restricted ration, or ad libitum food. They were killed at 60 days of age and their excised brains were dissected into six regions and homogenized. Densities of dopamine D1 and D2 receptors were assessed, after first estimating binding parameters for [3H]SCH 23390 (D1) and [3H]spiperone (D2) in chicken brain homogenates. Specific binding of both ligands was highest in basal telencephalon. Concentrations of dopamine and its metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid were also highest in basal telencephalon, whereas noradrenaline and adrenaline levels were highest in diencephalon. Dopamine concentration in basal telencephalon and noradrenaline concentration in diencephalon were increased significantly in response to food restriction, but no effect of feeding treatment was found in dopamine turnover, adrenaline levels, or D1 and D2 receptor densities in any brain region studied. The observed changes in brain catecholamine levels are consistent with roles for dopaminergic and adrenergic mechanisms in the control of food restriction-induced behavioural stereotypies in chickens.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1999

Melatonin content in plasma and large intestine of patients with colorectal carcinoma before and after surgery.

The distinct melatonin rhythm with higher concentrations during the darktime was found in plasma of both control patients and patients with colorectal carcinoma. Moderate surgery did not induce any changes in plasma melatonin levels, but a pronounced increase in both the day- and nighttime melatonin concentrations was found after surgical treatment for colon cancer. The melatonin content in the tumor tissue did not differ from that in the proximal and the distal parts of the resected gut, which were without signs of malignant changes. Neither concentrations of serotonin nor 5-hydroxyindole acetic acid differed among analyzed parts of the gut. Daytime melatonin concentrations in gut tissue (314.7 +/- 87.8 pg/g of wet tissue) were more than ten times higher than the daytime levels in circulation. It was hypothesized that increased levels of this hormone in the gastrointestinal tract may play an important protective role against the development of colorectal cancer via stimulation of the immune system, protection against free radicals, and interaction with fatty acid uptake and metabolism.

Aged↗
PubMed1998

Early changes of protein synthesis in myocardium and coronary arteries induced by NO synthase inhibition.

The question was addressed whether short-term (4 hour) NO deficiency, inducing an increase in blood pressure in anaesthetized dogs, does influence proteosynthesis in the myocardium and coronary arteries. A potentially positive answer was to be followed by the study of the supporting role of ornithine decarboxylase for the polyamines pathway. N(G)-nitro-L-arginine-methyl ester (L-NAME) (50 mg/kg per hour) was administered i.v. to inhibit NO synthase. After the first L-NAME dose diastolic blood pressure increased from 131.8+/-2.0 to 149.4+/-3.9 mm Hg (p<0.001) and was maintained at about this level till the end of the experiment. Systolic blood pressure only increased after the first dose (from 150.8+/-1.1 to 175.0+/-5.8 mm Hg, p<0.01), returning thereafter to the control level. Similarly, the heart rate declined only after the first dose (from 190.4+/-5.3 to 147.6+/-4.5 beats/min, p<0.01). Total RNA concentrations increased in the left cardiac ventricle (LV), the left anterior descending coronary artery (LADCA) and left circumflex coronary artery (LCCA) by 15.9+/-0.7, 29.7+/-1.3 and 17.6+/-1.0%, p<0.05, respectively. The same applied to [14C]leucine incorporation (by 86.5+/-5.0, 33.5+/-2.6, 29.3+/-4.1%, p<0.05, respectively). The above parameters indicated an increase of proteosynthesis in the LV myocardium and both coronary arteries LADCA and LCCA after short-term NO deficiency. Surprisingly, the ornithine decarboxylase activity in the LV myocardium decreased significantly by 40.2+/-1.6% (p<0.01) but the changes were not significant in the coronary arteries. This unexpected finding makes the role of polyamines in increasing proteosynthesis during a pressure overload due to NO deficiency questionable.

Animals↗
PubMed1997

Effect of Rooibos tea (Aspalathus linearis) on chick skeletal muscle cell growth in culture.

Rooibos tea (RT) extract contains natural antioxidants and scavenging agents. We investigated the effects of different concentrations of RT extract in medium on growth and changes of growth parameters of cultured chick embryonic skeletal muscle cells. Presence of 2, 10 and 100% of RT extract in the culture of primary cells significantly inhibited cell proliferation. The inhibition of cell growth reflected on decreased DNA, RNA and protein contents in primary cell culture and fibroblasts and myoblasts. The ability of the primary cells, fibroblasts and myoblasts to synthesize DNA and protein in the presence of RT extract, measured as an amount of [3H]thymidine and [3H]leucine incorporated into DNA and de novo synthesized protein, corresponded with decreasing DNA and protein contents in all three cell types. The inhibition effect of RT rose with increasing concentration of the tea extract in the culture medium. Ornithine decarboxylase activity was significantly affected only by 100% RT extract in every examined cell types. These results suggest that the inhibitory effect of RT extract on the growth of primary cells, fibroblasts and myoblasts is due to the potent scavenging activity of the RT extract.

Animals↗
PubMed1997

Influence of melatonin on chick skeletal muscle cell growth.

Melatonin as a highly lipophilic compound readily enters all subcellular compartments and acts by various mechanisms. In the present study, we investigated the effects of different concentrations of melatonin in medium (physiological and supraphysiological doses) at two treatment times (48 and 120 hr) on growth and changes of growth parameters of cultured chick embryonic skeletal muscle cells. The physiological doses of melatonin (100 pg to 10 ng/ml of medium) stimulated proliferation of cells and raised DNA, RNA protein contents and an incorporation of [3H]leucine into cell protein after 48 hr of treatment. The prolongation of exposure to melatonin in the physiological dose to 120 hr or an increase of melatonin dose to a supraphysiological one evoked the inhibition of cell growth and proliferation by decreasing the number of cells and the amount of labeled leucine incorporated into cell protein. Results demonstrate that melatonin's action in these cells is time and dose dependent.

Animals↗
PubMed1996

Plasma thyroid hormone and growth hormone patterns in precocial Japanese quail and altricial European starlings during postnatal development.

Plasma concentrations of thyroid hormones (TH) and growth hormone (GH) during postnatal development in the precocial Japanese quail (Coturnix japonica), and the altricial European starling (Sturnus vulgaris) were measured. Developmental changes in plasma TH found in the starling, differ considerably from those detected in quail. In quail rather high triiodothyronine (T3) values were measured during the first few days after hatching. Subsequently a steady decrease of plasma T3, to adult levels, was observed. Thyroxine (T4) concentrations did not change significantly during the period studied. In starlings, on day 1, plasma T3 was low and T4 was at or below the assay detection limit. An increase in concentrations of both hormones occurred between day 1 and day 5 after hatching. A gradual increase of T4 occurred afterwards, while plasma T3 levels remained nearly constant during this growing period. Plasma GH concentrations showed a similar pattern in both species. There was an increase during first days after hatching and GH concentrations peaked at day 7 in quail and day 5 in starlings. A subsequent decrease was observed in both species. Although the GH profiles in species studied were comparable, there were noticeable differences in their growth rates. Thus different developmental strategies have been reflected in different developmental patterns of TH in precocial Japanese quail and altricial European starling whereas developmental changes of GH levels were similar in both species.

Aging↗
PubMed1994

Effect of 3,5,3'-L-triiodothyronine on hepatic ornithine decarboxylase and thymidine kinase activity in rat after partial hepatectomy.

Partial hepatectomy (60%) led to the biphasic increase (first one at 4 h and second one at 48 h) of ornithine decarboxylase activity in the remnant rat liver. Daily administration of 3,5,3'-L-triiodothyronine (T3) (10 micrograms/100 g) to rats for 7 days before partial hepatectomy had little effect on the enzyme activity. At five days, ornithine decarboxylase activity declined to control level (sham operated controls) and its activity was significantly enhanced by T3. Ornithine decarboxylase gene expression in the rat liver (examined by Northern blot analysis using poly A+ mRNA) started to increase 4 h after partial hepatectomy, remained elevated for 48 h and decreased after 5 days. Its activity was not altered by T3 treatment. The activity of thymidine kinase increased progressively after partial hepatectomy, but its peak value was delayed by T3 administration. Plasma prolactin levels increased within 5-15 min after liver resection, then declined to control values and increased 24 h after the surgery. The data demonstrate that the changes in ornithine decarboxylase activity in the rat liver after partial hepatectomy might result from the direct effect of prolactin on the activity of enzyme rather than from its induction by hormone. Triiodothyronine administration altered both ornithine decarboxylase and thymidine kinase activities suggesting that T3 appears to regulate ornithine decarboxylase activity at post-translational level.

Animals↗
PubMed1994

Effects of thyroid hormones on chick embryo muscle cell culture.

The importance of thyroid hormones (TH) in the normal development of muscles has been repeatedly postulated. The effects of physiological TH doses on ornithine decarboxylase (ODC) and protein synthesis in muscle cells have been studied using cell cultures prepared from 11-day-old chick embryos. Triiodothyronine nuclear receptors in primary muscle cell culture were characterized on the basis of the specific binding analysis as a single receptor class with the equilibrium dissociation constant Kd = 1.2 +/- 0.4 x 10(-10) mol/l and binding capacity Bmax = 0.21 +/- 0.09 fmol/micrograms DNA. While the physiological amounts of both triiodothyronine (T3) and thyroxine (T4) stimulated ODC activity after 2 hr of treatment, only T3 had the same stimulatory effect after 4 hr of treatment. Twenty-four hour exposure of muscle cell culture to TH did not change ODC activity. The incorporation of [3H]leucine into proteins was elevated only after 120 hr incubation in the presence of T4. Application of T4 caused also an increase in the protein content after 24 hr.

Animals↗
PubMed1994

In vitro separation of embryonic chick skeletal muscle myoblasts and fibroblasts: comparison of their characteristics.

The aim of the present experiments was to test two methods of separating myoblasts and fibroblasts (selective plating, differential trypsinization) from chick embryonal skeletal muscle and to compare their characteristics. Ornithine decarboxylase (ODC) activity, the amount of incorporated [3H]leucine into proteins and incorporation of [3H]thymidine into DNA were significantly higher in myoblasts than in fibroblasts separated by selective plating. When comparing myoblasts and fibroblasts separated by differential trypsinization, significantly higher ODC activity and greater incorporation of [3H]leucine into protein, but no incorporation of [3H]thymidine into DNA, were found in myoblasts. Higher ODC activity and greater incorporation of labelled leucine were found in fibroblasts separated by the selective plating than in fibroblasts separated by differential trypsinization. The incorporation of labelled thymidine into DNA was higher in myoblasts separated by selective plating than in myoblasts obtained by differential trypsinization. The method of selective plating appears to be simpler and adequate for obtaining myoblastic and fibroblastic cell cultures with sufficiently low mutual contamination. The method of differential trypsinization involves a more drastic treatment of cells and is more time consuming.

Animals↗
PubMed1993

Effects of exogenous melatonin on some endocrine, behavioural and metabolic parameters in Japanese quail Coturnix coturnix japonica.

1. Melatonin administration in drinking water (5 micrograms/ml) to Japanese quail resulted in a 20-fold increase of plasma melatonin levels in comparison with the control, day time concentration (0.34 +/- 0.05 vs 6.88 +/- 1.10 nmol/l). 2. Plasma triiodothyronine levels increased (5.8 +/- 0.93 vs 7.97 +/- 0.64 nmol/l), corticosterone decreased (28.04 +/- 3.42 vs 15.96 +/- 2.56 nmol/l) and no significant changes were recorded in thyroxine concentration after the treatment. 3. A higher occurrence of sleeping and lower occurrence of pecking were found in melatonin treated quail. 4. Abdominal fat deposition as well as the content of total lipids in the breast muscle and triacylglycerols in plasma were decreased in treated birds indicating an inhibitory effect of melatonin on lipogenesis. 5. Melatonin increased RNA content in the breast muscle but did not affect plasma glucose concentration and body weight.

Animals↗
PubMed1993

Activity of ornithine decarboxylase in muscle of Japanese quail in hypergravity conditions.

Ornithine decarboxylase (ODC) is the rate limiting enzyme in the synthesis of polyamines which are generally required for animal cell proliferation. Because of many different stimuli changing the activity of ODC, the effect of hypergravity on muscle ODC activity in Japanese quail was investigated. Adult Japanese quail cockerels were exposed to 2G in the centrifuge permanently for 96 hours. The activity of ODC was determined by radioisotopic method in supernatant of homogenised breast and fibular muscles (m. pectoralis minor, m.superficialis fibularis). The activity of ODC was higher in breast muscle than in the fibular muscle in both, control and experimental groups. Exposition of quail to hypergravity evokes approximately 2 fold increase of ODC activity in both breast and fibular muscles. The results suggest that 96 hours of permanent hypergravitation (2G) caused activation of polyamine synthesis and their involvement in biochemical processes of adaptation to hypergravity.

Adaptation, Physiological↗
PubMed1993

Behaviour of newly hatched and adult Japanese quail and the feasibility of adaptation to weightlessness.

The aim of cosmic biology is to create conditions necessary for the long-term stay of man on cosmic orbital complexes and planetary stations. Such conditions should be provided by the autonomous closed ecosystem--a simplified model of the terrestrial biocenosis. As an experimental model of the higher heterotrophic link of this ecosystem the Japanese quail was chosen. This paper presents recent knowledge on the behaviour of newly hatched and adult quails under conditions of weightlessness. Videorecords made as part of the experiments aboard the MIR orbital station do not meet the criteria of systematic behavioural observation required for qualitative and quantitative behavioural analysis on earth. Nevertheless, the data is highly interesting and original, and was therefore analysed and summarized.

Adaptation, Physiological↗