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Biomedical subjects

J Kopecká

Publications and source records attributed to J Kopecká.

At least 19 recordsLinked to original sources
PubMed1996

Lack of evidence for the interaction between renin-angiotensin-aldosterone system and endothelin in vivo.

Aim of the study was to reveal the possible factors regulating plasma endothelin (ET) levels in vivo in patients with essential hypertension (EH) by the simultaneous determination of plasma renin activity (PRA) and plasma aldosterone (ALD). In addition, the possible relationship between ET and circulating endothelial cells as a marker of endothelial damage was also investigated. The postural test revealed a significant increase of ET levels (26.7 +/- 9 vs 11.5 +/- 3 fmol/ml, p < 0.05) in the upright position. Captopril administration did not change plasma ET levels. No significant correlation was found between ET and PRA or ALD. Although a tendency to a positive correlation between ET and circulating endothelial cells (as the marker of endothelial perturbation) was found, it did not attain statistical significance. Our data do not support the suggestion that the renin-angiotensin-aldosterone system plays a major role in the regulation of ET secretion in vivo in EH. Postural stimulation of ET secretion may be caused by other factors than renin-angiotensin-aldosterone system.

Adult↗
PubMed1995

[Chromopharmacokinetics and chromopharmacodynamics of drugs].

The review includes results of studies on the influence of biological rhythms in pharmacokinetics and pharmacodynamics of drugs. Rhythmical changes in physiological functions of the organism can change pharmacokinetic parametres. Their values depend on the time of administration. The properties and the number of receptors in the target tissue can also be under influence of time and in this way pharmacodynamic effect can be influenced. The results of chronopharmacological studies can be used in clinical practice and pharmaceutical research.

Animals↗
PubMed1992

[Chronopharmacokinetics of digoxin in compensated cardiac patients].

The authors provided evidence that the pharmacokinetics of digoxin are influenced by daily rhythms. Using doses of 0.125 mg digoxin by the oral route, after 12 hours they found a statistically higher serum digoxin concentration in the minimum before administration of the morning dose and in the maximum concentration after this dose, as compared with the minimal and maximal concentration before and after administration of the same dose in the evening. The other pharmacokinetic parameters--the area beneath the curve of serum concentrations, the time before the maximum concentration was attained and the total plasma clearance of digoxin did not differ. This chrono-pharmacokinetic relationship in compensated cardiac patients was comparable with data in the literature pertaining to healthy volunteers. To conclude it may be said that on administration of major does in the morning there is a greater risk of serum concentrations beyond the therapeutic range than during the administration of the same amount of digoxin in the evening.

Aged↗
PubMed1992

[Kinetics of gentamycin in premature infants with a low birth weight during the first four days of postnatal life].

The authors investigated in a group of 19 premature neonates with a low birthweight (0.65-2.1 kg) during the first four days of postnatal life the pharmacokinetics of gentamycin after indicated administration of 2 mg/kg of the antibiotic by the i.v. route by a 30-minute infusion in 18-hour intervals. Serum concentrations of gentamycin were assessed by immunoassay 0.5 hours before administration and then 0.5, 5.5, 11.5 and 17.5 hours after the 5th infusion, i.e. in a steady state. The maximum serum concentrations detected 0.5 hours after the completed infusion exceeded 10 mg/l in 21% of the neonates, while the minimal concentrations of the antibiotic before the next administration were above 2 mg/l in 42% of the infants. The calculation of pharmacokinetic parameters according to the one-compartment model revealed considerable interindividual differences of all values. The authors consider particularly important the low clearance value of the antibiotic (30.24 +/- 14.55 ml/kg.hour-1) which may lead to cumulation of gentamycin and its toxic action. Gentamycin administration to premature neonates should be associated with monitoring of serum concentrations of the drug which would make individual adjustment of the dosage possible.

Birth Weight↗
PubMed1990

[The effect of dopamine on hemodynamic and hormonal parameters in liver cirrhosis].

To 11 patients with liver cirrhosis (5 with ascites) and 6 controls a one-hour dopamine infusion, 1.5 micrograms/kg/min., was administered. In all before administration of the infusion catheterization of the hepatic veins and lesser circulation was performed with concurrent assessment of the cardiac minute volume by thermodilution, and haemodynamic measurements were repeated also after the dopamine infusion. Before the dopamine administration and after termination of the infusion the plasma renin activity was assessed (PRA), plasma aldosterone, the atrial natriuretic factor (ANF), prolactin and in some patients also plasma catecholamines. Dopamine administration was not associated with an increase of the cardiac output, heart rate or peripheral resistance; the infusion had only purely dopaminergic effects. Plasma prolactin declined after dopamine administration significantly in controls (from 29.17 +/- 7.01 to 11.83 +/- 3.22, p less than 0.05, in patients with liver cirrhosis without ascites) from 18.16 +/- 2.44 to 8.64 +/- 2.01, p less than 0.01) in patients with ascites liver cirrhosis (from 23.5 +/- 9.3 to 15.2 +/- 7.47, p less than 0.05). In the controls after the dopamine infusion PRA suppression occurred (from 2.37 +/- 0.81 to 0.9 +/- 0.27, p less than 0.05), while in patients with compensated liver cirrhosis (from 0.97 +/- 0.41 to 0.85 +/- 0.34, n.s.) and in patients with decompensated liver cirrhosis the PRA did not change significantly either (from 4.56 +/- 1.67 to 5.065 +/- 2.29, n. s.). After the dopamine infusion in none of the investigated patient groups changes of plasma aldosterone and ANF were recorded.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1990

[The effect of clonidine on humoral factors in patients with arterial hypertension].

Clonidine, an agonist of central alpha-2-adrenergic receptors, reduced the peripheral sympathetic activity. With regard to the mutual pathophysiological relationship of blood pressure regulating mechanisms, the authors wanted to find out whether after clonidine administration, in addition to the known suppression of catecholamine levels (CA), also changes in the concentration of other pressor and depressor humoral substances will occur. They investigated therefore in 15 patients with essential hypertension (EH) and in three patients with pheochromocytoma the urinary excretion of free noradrenaline (NA), adrenaline (A) and dopamine (DA), the plasma renin activity (PRA), the aldosterone concentration (PAC) and atrial natriuretic factor (ANF) in plasma, using radioimmunoanalysis, always before and 24 hours after clonidine administration (Haemiton retardR) by the oral route. Its administration led in patients with EH to a decline of NA and DA. On the other hand, in pheochromocytoma their urinary excretion did not change in an unequivocal way, and when it declined, never normal NA and DA levels were reached. A excretion remained unaltered in both groups of patients. The drop of PRA after clonidine as a result of the drop of peripheral adrenergic activity was not associated with an expected parallel drop of PAC but by its rise. This effect can be explained by a reduction of the tonic inhibition of PAC output when the DA level declines. The rise of ANF after clonidine administration will be the subject of subsequent investigations. It cannot be ruled out that this effect is due to the direct action of clonidine on alpha receptors in the heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Gland Neoplasms↗
PubMed1990

[Atrial natriuretic factor in liver cirrhosis. Relation to hemodynamic parameters].

In 12 patients with cirrhosis of the liver (six with ascites) and six controls the authors made catheterizations of the hepatic veins and portal circulation, assessing concurrently the in cardiac output by thermodilution. The patients with ascitic cirrhosis had, as compared with controls, a significantly higher portohepatic gradient, central venous pressure, mean pressure in the pulmonary artery and also pulmonary capillary wedged pressure and a significantly lower mean arterial pressure and systemic vascular resistance. These patients had also, as compared with controls, a significantly higher concentration of ANF (atrial natriuretic factor) in the pulmonary artery (15.89 +/- 2.26 vs. 8.04 +/- 0.97, p less than 0.01) and in the hepatic vein (7.44 +/- 0.44 vs. 3.91 +/- 0.63, p less than 0.01); the difference between ANF concentrations in the peripheral blood stream was not significant (9.52 +/- 2.46 vs. 5.71 +/- 1.24 n. s.). Patients with ascitic cirrhosis of the liver had a significantly higher calculated cardiac production of ANF than controls (24.36 +/- 3.44 vs. 8.12 +/- 2.9, p less than 0.01); the difference in the splanchnic extraction of ANF between patients with ascitic cirrhosis of the liver (0.46 +/- 0.1) and controls (0.51 +/- 0.06) was not significant. The ANF concentration in the pulmonary artery in patients with cirrhosis of the liver correlated significantly with the central venous pressure (r = 0.677, p = 0.02) and the pressure in the pulmonary artery in a wedged position (r = 0.639, p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Natriuretic Factor↗
PubMed1989

[New aspects and possibilities in the diagnosis of pheochromocytoma].

Pheochromocytoma is still a dangerous disease which is often difficult to diagnose. Evidence of the wide spectrum of its clinical picture was found in a group of 13 patients who were examined in the last 5 years. Drawing on their experience, the authors evolved a scheme of diagnostic examination. The primary biochemical examination involves the determination of urinary excretion of free catecholamines adrenaline, noradrenaline and dopamine simultaneously with their methylated metabolites metanephrine and normetanephrine, which help to make a more exact diagnosis in cases where the results of free catecholamines are not clear. Patients with pheochromocytoma lack diurnal rhythm of catecholamine excretion and thus the collection is made twice - by day and night. The determination of plasma catecholamines provides additional information. Only half the patients were found to have the level of vanillylmandelic acid increased. A significantly increased dopamine excretion points to the malignant form of the disease. The localization is established with the aid of computed tomography and, if needed, also by the determination of plasma catecholamines through selective cavae sampling. The final step serving to verify the diagnosis involves analysis of catecholamines in tumour tissue.

Adrenal Gland Neoplasms↗
PubMed1989

[Monitoring serum theophylline levels in children. Use of saliva for prediction].

In 28 children suffering from asthma--20 boys and 8 girls aged 3-19 years, weighing 18-79 kg--theophylline concentrations in serum and saliva were assessed. For detection the spectrophotometric method of Schack and Waxler and the fluoroimmunoassay TDA AMES were used. Under conditions of non stimulated salivary secretion the pH values of the secretion varied as a rule between 6.0 and 7.5 which did not influence significantly the amount of theophylline passing from blood into saliva. The authors found a very close correlation between the theophylline concentrations after administration of Syntophylline in saliva and serum (r = 0.9169, p less than 0.001) and Spophylline (r = 0.9369, p less than 0.001). Comparison of serum theophylline concentrations calculated from the salivary values on the one hand and the same serum theophylline concentrations actually assessed revealed that their difference varied up to 1 microgram.ml-1.

Adolescent↗
PubMed1988

Serum parathyroid hormone in patients with pheochromocytoma.

Studies were performed in seven unselected patients with proven pheochromocytoma pre-operatively. Serum immunoreactive parathormone and calcium levels were found to be normal in all our patients with sustained symptoms and signs of pheochromocytoma. In spite of a high circulating concentration of epinephrine or norepinephrine we did not find out any changes in serum calcium and parathormone levels.

Adrenal Gland Neoplasms↗
PubMed1987

Failure to detect acute effects of insulin hypoglycemia on serum PTH and calcium in normal subjects.

The effect of insulin induced hypoglycemic stress on parathyroid hormone serum level in man were evaluated. Porcine crystalline insulin (0.2 U kg-1 i.v.) caused symptomatic hypoglycemia and increase of adrenaline level in serum in all subjects. In the present study we could not detect any significant effects of insulin and of insulin induced hypoglycemia on serum parathormone and calcium levels, though such hypoglycemia is a potent stimulus to endogenous catecholamine secretion. The results support the view that the adrenergic system does not play any major role in regulating the secretion of parathormone which is contrasting to some findings reported by others.

Adult↗
PubMed1986

Effect of sleep deprivation on cholesterol metabolism and triglyceridaemia in male volunteers.

The effect of 5-day sleep deprivation (SD) on cholesterol metabolism, together with triglyceridaemia, was studied in seven healthy male volunteers. A 3-day control period was followed by 5 days (120 h) complete SD and 4 days recovery. Blood was collected at 9 a.m. and at 9 p.m. Vastus lateralis muscle biopsy was performed during the control period, on the 5th day of SD, and on day 3 of recovery. The value of muscle cholesterol was related to the non-collagen protein content. The plasma triglycerides (TG) varied in a circadian biorhythm, the amplitude of which declined gradually during SD. The morning triglyceridaemia was significantly decreased on days 3-5 of SD (35%-79% of initial values). On days 4 and 5 of SD, plasma cholesterol fell significantly to 78% and 88% of control values, respectively. The ratio of its esterified to unesterified fractions remained unchanged throughout SD. Basal activity of lecithin cholesterol acyltransferase (LCAT) showed no diurnal biorhythm; on the last 2 days of SD, LCAT activity fell significantly to 71%-80%. In contrast, the decrease in fractional esterification rate (FER) was insignificant. In the vastus lateralis muscle, total cholesterol (TC) was decreased by 40% at the end of SD, the reduction being greater for cholesterol esters (CE) (by 63%) than for free cholesterol (FC) (by 36%). The relative proportion of CE significantly decreased from an initial 14.7% to 9.2% on the last day of SD. During recovery after SD, plasma cholesterol and TG slowly returned to normal. LCAT activity and FER recovered quickly, within 48 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Fractional cholesterol esterification rate and muscle cholesterol of healthy young men.

A group of fourteen healthy young male volunteers was examined to define more exactly the relations between lecithin cholesterol acyltransferase activity (LCAT), fractional cholesterol esterification rate (FER), total cholesterol (TC) and its free and esterified fractions (FC, CE) in skeletal muscles under physiological conditions. The mean values (+/- S.D.) of LCAT activity (95.4 +/- 16.3 mumol .1(-1) per hour), and FER (7.45 +/- 1.54% per hour) corresponded to published data on normolipidaemic healthy men of normal body weight. The mean value of TC in muscles was 332 +/- 83 micrograms per 100 mg of non-collagen protein, of which 14 +/- 7.4 per cent was formed by cholesterol esters. There was positive correlation between TC in muscles and age. Significant positive correlations between FER and the content of esterified cholesterol in muscles, and between FER and the proportion of esterified to total muscle cholesterol were found. These results suggest a close interrelation of cholesterol ester metabolism in the plasma and in slow pool tissues.

Adult↗
PubMed1984

Urinary excretion of free catecholamines in long-term treatment with dopaminergic agonists.

Urinary excretion of free adrenaline, noradrenaline and dopamine was examined in 12 patients with active acromegaly before and during long-term therapy (6-22 months) with ergoline derivatives bromocriptine (20-30 mg daily) and lisuride (1-2 mg daily). A significant fall in noradrenaline values (4.5 +/- 0.95 (SEM) nmol/h on v.s. 15.3 +/- 3.8 nmol/h before the treatment, P less than 0.01) was found in the treated patients. Adrenaline excretion rose in most patients but the difference was not significant (1.43 +/- 0.33 nmol/h on v.s. 1.02 +/- 0.36 nmol/h before the treatment, P greater than 0.05). No significant change was seen in the dopamine excretion (71.3 +/- 9.58 nmol/h on v.s. 75.0 +/- 7.0 nmol/h before the treatment, P greater than 0.05). Our studies confirm the blood pressure lowering effect of bromocriptine and lisuride even when used on a long-term basis. This effect seems to be associated with reduced sympathetic activity.

Acromegaly↗
PubMed1984

Lecithin-cholesterol acyltransferase activity in children in the early neonatal period.

Changes in the rate of plasma cholesterol esterification occurring shortly after birth were followed by determining the activity of lecithin-cholesterol acyltransferase (EC 2.3.1.43) in newborn children, and at the age of 3 days and 3 months. The radioassay method using 'common' substrate was applied. The molar esterification rate (MER) in umbilical cord serum was about half of the values found in the sera of 3-day-old and 3-month-old children, or adult subjects. Because of a positive correlation between MER and the plasma concentration of unesterified cholesterol, the values of fractional esterification rate in children were in good agreement with those characteristic for healthy adults.

Adult↗