Biomedical subjects

O Lapcík

Publications and source records attributed to O Lapcík.

28 records · Page 2Linked to original sources

PubMed1996

[Epitestosterone as an endogenous antiandrogen in men].

The authors assessed in the plasma of 156 boys and men aged 6 - 65 years and in prostatic tissues of 15 men aged 55 - 82 years epitestosterone, C19-steroid with anti-androgenic properties. It was revealed that during the prepubertal period the epitestosterone level is higher than that of testosterone, in adult age the epitestosterone is about ten times lower than the testosterone concentration. In tissue of hyperplastic prostates the epitestosterone level is comparable with the androstendione level; it is about twice as high as the testosterone level and approximately half as high as the dihydrotestosterone level. Thus at least during the prepubertal period in boys and in the androgen-dependent prostate tissue a more significant participation of epitestosterone in the regulation of androgen-dependent processes must be taken into consideration.

Adolescent↗

PubMed1995

A novel radioimmunoassay of allopregnanolone.

A radioimmunoassay for determination of 3 alpha-hydroxy-5 alpha-pregnan-20-one (allopregnanolone) in serum or plasma has been developed and evaluated. The method employs rabbit antiserum to 3 alpha-hydroxy-5 alpha-pregnane-11,20-dione-11-O-carboxymethyloxime bovine serum-albumin conjugate and tritiated radioligand. The main cross-reactant interfering in the assay, progesterone, is eliminated by permanganate oxidation. Two assay variants were compared, with and without a micro-column chromatography. The simplified variant appeared to be reliable enough for determination of allopregnanolone in normally menstruating women at luteal phase, whereas the column-chromatography step is necessary when analyzing samples of expected low analyte concentration as in women in follicular phase, postmenopausal women, or in men. The levels of allopregnanolone in healthy women correlated excellently with progesterone in agreement with previous findings.

Antibody Specificity↗

PubMed1995

Radioimmunoassay of three deoxycorticoids in human plasma following HPLC separation.

A radioimmunoassay of three deoxycorticoids, namely 11 beta,17 alpha-dihydroxy-4-pregnene-3,20-dione (21-deoxycortisol), 17 alpha,21-dihydroxy-4-pregnene-3,20-dione (11-deoxycortisol), and 21-hydroxy-4-pregnene-3,20-dione (11-deoxycorticosterone) which are important for differential diagnosis of congenital adrenal disorders, is described and evaluated. Antisera against 3-(O-carboxymethyl)oximes conjugated to bovine serum albumin were raised in rabbits. The radioligands were prepared by radioiodination of previously synthesized homologous tyrosine methyl ester derivatives. Following diethyl ether extraction, the steroids were separated from each other and from cross-reactants by HPLC using a Nucleosil C8 reverse-phase column and a methanol-water mixture (7:5, v/v) as an eluent. Normal levels of analyzed steroids ranged from 0.02 to 0.348, 0.185 to 3.80, and 0.013 to 0.299 nmol/l, for 21-deoxycortisol, 11-deoxycortisol and 11-deoxycorticosterone, respectively. The levels of both deoxycortisols rose significantly after ACTH treatment. Data are given with respect to the concentrations of these steroids in some pathological situations such as 21-hydroxylase and 11 beta-hydroxylase block, hyperaldosteronism, and polycystic ovary syndrome.

Adolescent↗

PubMed1995

Plasma levels of epitestosterone from prepuberty to adult life.

Epitestosterone has for a long time been considered as a biologically inactive steroid. However, recently a distinct antiandrogenic activity of this naturally occurring endogenous epimer of testosterone has been demonstrated. Epitestosterone plays a role in the control of doping with testosterone, since an arbitrary ratio of testosterone to epitestosterone in urine has been accepted as a marker for testosterone abuse. For this reason, its urinary excretion has been examined intensively by several authors. On the other hand, its concentration in the blood of men was reported only randomly in a few cases. In the present study the epitestosterone level in human plasma was determined by a specific radioimmunoassay and the concentration of epitestosterone was established in age groups of males of 6 to 65 years of age. There is a clear age dependence of epitestosterone plasma concentration in males. In young boys before puberty, antiandrogenic epitestosterone prevails over testosterone, in adults a striking decline of the ratio epitestosterone:testosterone can be observed.

Adolescent↗

PubMed1994

The effect of long-term glucocorticoid therapy on glucocorticoid receptor content and on steroid response to ACTH.

The effect of long-term glucocorticoid therapy for systemic diseases on glucocorticoid receptor (GR) content and on basal and ACTH-stimulated levels of plasma and salivary cortisol 17 alpha-hydroxy-progesterone, androstenedione, 11 beta-hydroxyandrostenedione, DHEA, its sulfate and sex hormone-binding globulin (SHBG), as well as on basal levels of aldosterone, was investigated in a group of 24 children treated with prednisone for at least 8 months. The therapy was interrupted 24 h before the ACTH test and before plasma and saliva sampling. The control group consisted of 21 healthy children of corresponding age and sex. The patients were divided into two subgroups with normal and subnormal basal cortisolemia, they also differed in their response to ACTH. The GR levels in patient groups were indistinguishable from those found in controls. No correlation was found between GR content and basal levels of the above steroids or their response to ACTH. The best markers, apart from basal cortisolemia, for evaluation of the degree of suppression of adrenal function appeared to be the response of salivary (but not of plasma) cortisol and 17 alpha-hydroxy-progesterone to ACTH. Surprisingly, significantly lower levels of SHBG levels, which rose markedly after ACTH, were found in all the patients.

Adolescent↗

PubMed1993

The effect of epitestosterone on the plasma levels of LH and FSH in ovariectomized immature rats.

Immature ovariectomized female rats primed with estradiol or without estrogen priming were treated with epitestosterone i.p. After 7 h blood was collected and LH and FSH levels were determined. The dose-response relationship was a biphasic one. LH and less markedly FSH levels decreased under epitestosterone treatment with doses up to 10 mg, whereas at higher doses an increase of gonadotrophins was observed.

Animals↗

PubMed1990

[Determination of bone mineral content in vivo in dialyzed patients using photon radiation absorptiometry].

In a group of 47 women and 54 men with chronic renal failure included in a regular haemodialyzation programme the mineral content of bone was assessed using the method of radiation absorption of the radioisotope americium (241Am) on a Bone mineral detector of Gambro Co. The bone mineral content was reduced in men and women by 22%, as compared with healthy subjects of the same age and sex. The reduction was more marked in patients dialyzed for longer periods and when there were lamoratory signs of activity of the process.

Absorptiometry, Photon↗

PubMed1990

Beta 2-microglobulin serum levels during dialysis: effect of cuprophan and serum osmolality changes.

New cuprophan dialysers were used in twenty, re-used dialysers in twelve dialyses and new dialysers in ten sequential ultrafiltrations. Serum beta 2-microglobulin (beta 2m) concentration was measured before and after all these procedures. Serum osmolality changes were compared with changes in serum beta 2m concentrations. These concentrations rose in dialyses with new and re-used dialysers, but remained unchanged during sequential ultrafiltration. beta 2m increased with serum hypo-osmolality, decreased with serum hyperosmolality and did not change during iso-osmolar dialysis. These results indicate that cuprophan membrane does not raise beta 2m concentration during dialysis. It is hypo-osmolality that is responsible for the increment of beta 2m in serum.

Cellulose↗

PubMed1989

[What is the reason for the increase in beta-2-microglobulin levels in the blood when using cuprophane dialysis membranes?].

The authors discuss the question of whether the growing blood concentration of beta-2-microglobulin in the course of haemodialysis is due to the bioincompatibility of the cuprophane membrane or to changes in serum osmolality. x531p4cuprophane dialyzer was used for 20 acts of haemodialysis, a regenerated one for 12, a new one for 10 sequence ultrafiltrations. The serum concentration of beta-2-microglobulin was measured prior to and after haemodialysis, and so was serum osmolality. The changes in beta-2-microglobulin concentration during haemodialysis were compared with serum osmolality changes. The levels of beta-2-microglobulin rose during haemodialysis using a new as well as a regenerated dialyzer but remained unaltered during sequence ultrafiltration. They increased in the presence of serum hypoosmolality, remained unchanged in normal osmolality, and decreased in hyperosmolality. The results show that the cuprophane membrane is not the source of increased beta-2-microglobulin, but that serum hypoosmolality developing during haemodialysis is the factor responsible.

Biocompatible Materials↗

PubMed1989

[Accumulation of aluminum in the dialyzed patient: incidence, causes and possibilities of prevention].

In a group of 60 patients dialyzed for more than three years laboratory signs of aluminum accumulation were found in 30%. Serum Al values correlated with the increment in the desferal test. Orally administered aluminium hydroxide is a significant source of Al accumulation, as has been demonstrated by the decline of the blood aluminium level after its discontinuation and a negative desferal test in patients to whom it was not prescribed. The passage of Al across the dialyzation membrane depends on the difference between the ultrafiltrable ratio of the blood value and the Al concentration in the dialyzate. Therefore even a concentration of 10 micrograms/l Al in the dilyzate, so far recommended as "safe", can lead to a rise of the Al blood level during haemodialysis and to Al accumulation in tissues. Effective removal of Al from the organism is possible only during haemodialysis after previous administration of Desferal. Unless an adequate substitute of aluminium hydroxide will be available and a completely aluminium free dialyzate, Al accumulation can be prevented by preventive administration of Desferal.

Adult↗