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H Brozmanová

Publications and source records attributed to H Brozmanová.

16 recordsLinked to original sources
PubMed2002

[Determination of cyclosporine A using high-performance liquid chromatography].

Recent analytical possibilities of therapeutic drug monitoring (TDM) of cyclosporine A (CyA) both in solid organ transplanted patients and in patients with autoimmune diseases are described. The standard method for determination of CyA in blood is a validated HPLC method. HPLC methods were developed which make it possible to determine not only the parent drug, but also the main metabolites of CyA: AMI (M17), AM9 (M1), and AM4N (M21). Preparation of blood samples, their extractions and purifications are discussed. Chromatography is usually carried on C18 or CN columns by isocratic elution under high temperature (70 degrees C). CyD or CyC is used as the internal standard HPLC-MS method enables unambiguous identification of CyA metabolites after their separation on a chromatographic column and it is used mostly for research purposes only.

Chromatography, High Pressure Liquid↗
PubMed2002

[Therapeutic monitoring of cyclosporine A].

Cyclosporine A (CyA) is a drug with a specific influence on the immune system and it is used both to prevent tissue rejection of transplanted organs and to treat autoimmune diseases. The properties, metabolism, and methods of therapeutic drug monitoring (TDM) in patients under immunosuppressive therapy are described. TDM of CyA reflects the clinical condition of the patient during immunosuppression and may include pharmacokinetic and pharmacodynamic data obtained either from measuring CyA levels in blood, or from determining some other parameters, which are modulated by CyA (II-2). Although TDM is mainly based on analyzing trough levels of CyA, the determination of the whole biological exposition calculated as AUC enables better correlation with the clinical state of patients. Pharmacodynamic parameters have not been measured routinely yet.

Cyclosporine↗
PubMed2001

Evaluation and comparison of therapeutic monitoring of whole-blood levels of cyclosporin A and its metabolites in renal transplantation by HPLC and RIA methods.

BACKGROUND: The aim of the work was to evaluate the possibility to estimate the level of cyclosporin A (CyA) metabolites as the difference of radioimmunoassay (RIA) non-specific and RIA specific methods. METHODS: Blood samples of renal transplant patients were analyzed by three different methods: RIA specific method (CYCLO-Trac, DiaSorin, USA) (RIA(SP)), RIA non-specific method (Immunotech, Czech Republic) (RIA(NS)), and high performance liquid chromatography (HPLC) method. RESULTS: Although values obtained by RIA(SP) correlated well those obtained by HPLC (RIA(SP)=0.995.HPLC+9.68; r(2)=0.962, n=448), the results of HPLC methods were lower by 8%. The values obtained by RIA(NS) were 2.57 times higher than the values obtained by RIA(SP) (RIA(SP)=0.356RIA(NS); r(2)=0.713, n=448). The ratio (CyA+CyA metabolites)/(CyA) calculated as the ratio RIA(NS)/RIA(SP) values for 42 renal transplant patients was relatively stable for each particular patient. The sum of selected CyA metabolites (M1+M17+M21) measured by HPLC correlated well with that estimated from the difference of RIA(NS)-RIA(SP): HPLC(metab)=0.921.(RIA(NS)-RIA(SP))+21.3; (r(2)=0.746, n=448). CONCLUSION: The combination of both the specific and non-specific methods for the determination of CyA presents an improved means for the TDM of CyA and CyA metabolites in renal transplant patients. Moreover, a combination of both methods can help to elucidate some unexpected events, such as the persistence of high cyclosporin blood levels.

Blood Chemical Analysis↗
PubMed2001

Influence of P-glycoprotein on the transplacental passage of cyclosporine.

The transfer kinetics of cyclosporine across the dually perfused rat placenta in the maternal to fetal direction and a possible involvement of P-glycoprotein were investigated. The transplacental clearance of cyclosporine in the materno-fetal direction was found to be dependent on the maternal inflow concentration of cyclosporine. Coadministration of cyclosporine with an excess of quinidine or chlorpromazine into the maternal compartment revealed 1.7- and 1.9-fold increase in cyclosporine concentration in the fetal compartment. In the experiments where quinidine was present both in the maternal and fetal compartments, cyclosporine appeared in the fetal compartment significantly faster, and its amount was three times higher when compared with controls. Conversely, quinidine or chlorpromazine did not affect the transplacental passage of L-[(3)H]-glucose. The interference of quinidine with the metabolism of cyclosporine in the placenta was excluded because only traces of M-1 and M-17 metabolites were found in the fetal solutions. Sodium azide, a mitochondrial respiratory inhibitor, was found to double the rate of cyclosporine, but not L-[(3)H]-glucose, passage across the placenta. Our findings indicate that P-glycoprotein pumps cyclosporine out of the trophoblast cells of the rat placenta in the ATP-dependent manner and restricts the passage of cyclosporine across the placental barrier.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

High-performance liquid chromatographic method for therapeutic drug monitoring of cyclosporine A and its two metabolites in renal transplant patients.

A novel fast HPLC method was developed for the determination of cyclosporine A (CyA) and its two metabolites M17 (AM1) and M21 (AM4N) in blood. Whole blood was precipitated with zinc sulphate, extracted with diethyl ether, evaporated, dissolved in aqueous methanol and partitioned twice with n-hexane. Chromatography was carried out using a microbore RP-column under isocratic elution with acetonitrile-methanol-water (200:80:140, v/v/v) at 70 degrees C and a detector set at 205 nm. Linearity for all three compounds was tested in the range of 1-1000 ng/ml. Recovery was 97-109%, and a coefficient of variation was 1.6-8.8% depending on the particular compound and its concentration. The method was used for a group of renal transplant patients having an inadequate response to CyA therapy in order to evaluate the possible role of CyA and its metabolites on the occurrence of hypertension and other toxicological events.

Calibration↗
PubMed1984

Studies on the inhibitory effect of apomorphine and bromocryptine on basal and TRH induced level of TSH and PRL in hypothyroid rats under pentobarbiturate anesthesia.

Groups of male rats were inserted with polyethylene tubings into femoral artery and vein under pentobarbiturate anesthesia and small blood samples were frequently taken for the estimation of TSH and PRL under maintaining isovolemia. After a single injection of apomorphine (12 mg kg-1) or bromocryptine (20 mg kg-1) much more expressed effect of these drugs on a decrease of PRL level in plasma was found than that on a decrease of TSH level and similar observation was made with the use of continuous i.v. infusion of apomorphine (50 micrograms in 20 microliter per min for 180 min). Finally, under the above dose of infused apomorphine, the effect of TRH on the increase of TSH level was depressed at the 30th min as compared to that 0 and 120th min of infusion. In addition, at 120 min of infusion the effect of TRH was significantly higher than that at 0 min. These results suggest that the effect of apomorphine may take place at the pituitary level.

Anesthesia↗
PubMed1983

In vivo study of iodothyronine deiodination in rat liver: effect of salicylate on biliary excretion of several iodothyronines.

Biliary excretion of total (i.e. conjugated plus unconjugated) thyroxine (T4), 3,5,3'-triiodothyronine (T3), 3,3',5'-triiodothyronine (rT3), 3,5-diiodothyronine (3,5-T2), 3,3'-diiodothyronine (3,3'-T2) and 3',5'-diiodothyronine (3',5'-T2) was measured with the aid of specific radioimmunoassay in 17 control rats and in 31 rats injected sodium salicylate i.v. (200 mg kg-1). The animals were anesthetized with pentobarbiturate and the samples of bile were taken in subsequent 2 h periods from a drained bile duct. In controls a gradual decrease of excretion of all compounds measured was found during 10 h observation period. In contrast, after salicylate injection a transient increase of total bile volume and of T4, T3 and 3,5-T2 excretion was observed followed by a remarkable decrease, while a multifold and prolonged increase of the excretion of rT3, 3,3'-T2 and 3',5'-T2 was found. These data suggest an acute and remarkable effect of salicylate on T4 deiodinating pathway in the liver.

Animals↗
PubMed1982

Direct quantitative estimation of several iodothyronines in rat bile by radioimmunoassay and basal data on their biliary excretion.

A method was developed for the hydrolysis of conjugated iodothyronines in bile with the aid of beta-glucuronidase/arylsulfatase and for subsequent direct estimation of total and free iodothyronines with the aid of specific radioimmunoassay. The amount of conjugated fraction could then be calculated from the difference. Thus, basal biliary excretion of several iodothyronines was measured in 31 normal, fed rats in which the bile duct was drained with polyethylene tubing under pentobarbiturate anesthesia and the bile was collected for 2 h. The free fraction of thyroxine, 3,5,3'-triiodothyronine and 3,3'-diiodothyronine was approx. 30% of total content, while that of 3,3',5'-triiodothyronine and 3,5-diiodothyronine was approx. 20% and that of 3',5'-diiodothyronine was less than 10%. This suggests some considerable differences in the conjugation of individual iodothyronines in the liver. The concentration of T4 in bile was about the same as in plasma, while that of other iodothyronines was about 3-8 times higher than in plasma. This shows close interrelations between the iodothyronine deiodinating pathway in liver cells in vivo and the spectrum of iodothyronine in bile. The average ratio of T3/rT3 as found in bile was about 4.

Animals↗
PubMed1981

Immediate opposite effect of salicylate on thyroxine and 3,5,3'-triiodothyronine versus 3,3',5'-triiodothyronine level in plasma in rats.

In a total of 46 male rats polyethylene tubings were introduced into femoral artery and vein under pentobarbiturate anesthesia. Then heparin (300 U kg-1) was injected at 60-90 min after pentobarbiturate and two control blood samples were subsequently taken. After that sodium salicylate (200 mg kg-1) was injected i.v. and blood samples were taken at 30-420 min later. An immediate decrease of the thyroxine (T4) level in plasma to about 20% of original level and that of 3,5,3'-triiodothyronine (T3) to about 60% of that was found, while the level of 3,3',5'-triiodothyronine (rT3) was increased 20%. It was concluded that the administration of salicylate results in an immediate displacement of T4 and T3 from plasma protein binding and possibly inhibits the conversion of T4 to T3 and of rT3 to 3,3'-diiodothyronine which results in an increase of rT3 level in plasma. This might by partially prevented by an inhibiting effect of salicylate on the binding of rT3 to plasma proteins.

Animals↗
PubMed1980

Changes in adenylate cyclase activity in rat pituitary after TRH and T3 injection in vivo.

Increased activity of adenylate cyclase in whole anterior pituitary was repeatedly found in groups of 3-6 adult male rats 5 min after iv injection of 10, 100 and 200 nmol of TRH kg-1. After the administration of 100 nmol TRH kg-1 the activity of adenylate cyclase was significantly increased at 2, 5, 10 and 30 min with a peak level at 5 min, while at 60 min the values did not differ from controls. The level of TSH in serum was significantly increased in all TRH injected groups with a peak value at 10 min, while no dose-response relationship was found at 5 min. Finally, the activity of adenylate cyclase was significantly decreased in animals injected with 20 nmol of L-triiodothyronine kg-1 180 min before sacrifice, the decrease being not overcome by 100 nmol TRH kg-1 injected 5 min before sacrifice.

Adenylyl Cyclases↗
PubMed1980

In vitro effect of TRH on adenylate cyclase and cAMP in rat anterior pituitary and on TSH and PRL release into incubation medium.

Rat anterior pituitaries were incubated for 20 min with 1, 5 or 20 nmol TRH ml-1 and cAMP was measured in the homogenate of pituitary tissue after incubation, while TSH and PRL release into the medium was estimated with the aid of specific radioimmunoassay. In a similar experiment the activity of adenylate cyclase in pituitary homogenates was measured after the incubation with 0.5, 1.0 or 5.0 nmol TRH ml-1. Significant increase of TSH and PRL in the medium was found after 5 and 20 nmol TRH ml-1, while cAMP was significantly increased after 20 nmol TRH ml-1 only. The activity of adenylate cyclase was significantly increased after all doses of TRH used. In general, these findings are consistent with current views on the effect of hypothalamic hormones via adenylate cyclase - cAMP system and show that the responsiveness and sensitivity of an in vitro system using whole pituitaries appears to be less that of in vivo system.

Adenylyl Cyclases↗
PubMed1980

Acute effect of salicylate on T4 and T3 levels in plasma and their excretion by bile in rats.

Male Wistar rats weighing about 400 g were anaesthetized with pentobarbiturate (40 mg kg-1) i.p. and thin polyethylene tubings were inserted in left femoral artery and vein as well as in a bile duct. Blood samples were taken at 30-60 min intervals for 6 h. The total bile was collected to pre-weighed glass vials. With the aid of radioimmunoassay the level of thyroxine (T4) and 3,5,3'-triiodothyronine (T3) was estimated in plasma and the total excretion of these compounds by bile was measured after the incubation of bile aliquots with beta-glucuronidase-arylsulphatase. After i.v. injection of sodium salicylate (S; 80 mg kg-1) a significant decrease of T4 and T3 in plasma was found compared either to the initial level found in the same animals or to that found in controls not injected with S. Total excretion of bile was increased within 2 h after the administration of S. Under these conditions, the excretion of T4 was increased, while that of T3 was decreased. It is suggested that the effect of salicylate under the experimental conditions used consists of: 1. displacement of iodothyronines from plasma protein binding; 2. increased bile excretion (during the initial period after the administration of S) presumably due to the increased blood flow through the liver.

Animals↗
PubMed1980

Studies on the effect of pentobarbiturate, ether and heparin on plasma thyroxine level in rats.

In groups of 9 to 20 adult male rats decapitated at 0, 15 or 60 min after i.p. injection of saline or at the same intervals after 2 min exposure to ether no differences in plasma thyroxine level were found. In groups of 5-6 animals a significant decrease of thyroxine level in plasma was observed at 30 min after i.p. injection of pentobarbiturate (40 mg kg-1) and unsignificant decrease after 800 and 2400 U heparin i.p. per animal. Finally, in 58 animals a linear decrease of plasma thyroxine level was found during 480 min beginning from about 60th to 90th min after the onset of pentobarbiturate anaesthesia (40 mg kg-1 followed by 20 mg kg-1 every 60-90 min). It was concluded that the blood clotting preventive dose of heparin (i.e. 300 U per 400 g animal) presumably does not interfere with the level of thyroxine in plasma, while pentobarbiturate apparently results in a considerable decrease of that.

Anesthetics↗
PubMed1979

Does a short-term draining of bile duct affect the plasma thyroxine level in rats?

In three groups of male rats weighing about 350 g and fed normal pelleted diet the left femoral artery and vein were cannulated under pentobarbiturate anesthesia and in samples of plasma obtained between 0 and 6 h after the injection of heparin the level of thyroxine (T4) was measured with the aid of specific radioimmunoassay. In addition, in Group A (22 animals) and C (17 animals) also the bile duct was cannulated and the total bile was collected into a flask for the same period. In addition, the animals of a Group C were thyroidectomized by electrocoagulation immediately before "O h". The Group B consisted of 18 sham-operated animals in which, in addition to the cannulation of blood vessels, only laparotomy and separation of bile duct without cannulation were made. In all groups a linear decline of plasma T4 level was found corresponding to a half-life of about 11 h. Since there were no significant differences in the slope of regression line between groups, it was concluded that the period of draining bile duct for 6 h was presumably too short to interfere significantly with the absorption of T4 in lower intestine and ileum and that the uniform decline of T4 level in plasma in all groups was presumably due to the effect of pentobarbiturate.

Animals↗