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Biomedical subjects

J Bednár

Publications and source records attributed to J Bednár.

At least 19 recordsLinked to original sources
PubMed2003

Developmental changes in uncoupling protein 1 and F1-ATPase subunit levels in the golden hamster brown adipose tissue mitochondria as determined by electron microscopy in situ immunocytochemistry.

The postnatal developmental changes in mitochondrial uncoupling protein 1 (UCP 1) and F1-ATP synthase (ATPase) subunit levels in the interscapular brown adipose tissue (BAT) were studied in golden Syrian hamsters (Mesocricetus auratus) using electron microscopy in situ immunocytochemistry. The relatively low initial density of 5 nm gold conjugated anti-UCP 1 immunocomplexes gradually increased from 7- to 21-day-old animals and numerous immunocomplexes were found on the mitochondrial membranes of adult hamsters. At the age of 7-9 days, a positive reaction was also detected in the cytoplasm of BAT adipocytes. Immunolocalization of F1-ATPase subunit indicated its presence in BAT mitochondria and cytoplasm of 7- to 9-day-old animals. However, contrary to UCP 1, intensity of the immunostaining of F1-ATPase subunit rapidly decreased both in mitochondria and cytoplasm between the 10th and 21st postnatal day and it became stabilized in adult animals at a very low level restricted to mitochondria. These results confirm that profound changes in the enzymatic apparatus of BAT mitochondrial membranes, leading to formation of thermogenic mitochondria, occur not until the early postnatal period of hamster ontogenetic development.

Adipose Tissue, Brown↗
PubMed1996

The contribution of secondary heavy particles to the absorbed dose from high-energy photon beams.

High-energy photon radiotherapy sources produce non-negligible numbers of secondary heavy particles (neutrons, protons and alphas) which contribute to the dose in a patient. They also present a radiation protection problem. The contribution of such particles to the absorbed dose in a tissue-like medium and to the equivalent dose is considered in this study experimentally. Track etch detectors were chosen as a basic type of measuring instrument: cellulose nitrate Kodak LR115 and polyallyldiglycol carbonate CR39 were used as detectors. Several methods of directly read datum (track density, track parameter, LET spectrum etc) interpretation have been analysed. It has been ascertained that the contribution of secondary heavy particles represents approximately 0.002 of the photon dose and 0.02 of the equivalent dose, both at 50 MeV as maximum photon energy. The contribution of a 20 MV bremsstrahlung beam is roughly one-fifth of that at 50 MV.

Alpha Particles↗
PubMed1994

[The present status of laboratory diagnosis of thyropathies. An analytical review].

At present, immunoanalysis is of dominant importance in the laboratory diagnostic of the diseases of the thyroid gland. The present paper briefly surveys the current methods of detecting the function of the thyroid gland, of further precision of diagnosis (particularly in the diseases of the autoimmunity origin) and some of the methods of early detection of carcinoma of the thyroid gland. Their methodical development, clinical importance and circumstances which could influence the results of determination and cast doubt on their validity are briefly characterized.

Humans↗
PubMed1992

[Diagnostic significance of osteocalcin levels in the classification of senile osteoporosis].

The authors investigated the osteocalcin (BGP) serum level in 55 women with the senile type of osteoporosis. According to BGP values they divided the group into three sub-groups. Lower values were recorded in 27 subjects (50%), normal values comparable with a control group of 13 healthy women of equal age were recorded in 21 subjects (38%) and in a small sub-group of 7 women (12%) the BGP level was raised or high. Senile osteoporosis can be also heterogeneous, characterized by a reduced, normal but in some also an elevated metabolic turnover of bone. It is, however, possible that this is a question of different stages and at the time of examination the mentioned status was recorded. An opportunity to examine BGP levels would be a great asset for osteological departments, among others also for the classification of osteoporosis with regard to the rate of the metabolic turnover or remodelling activity and would provide doctors with valuable information for decision taking on rational therapy.

Aged↗
PubMed1992

Lack of stimulating effect on thyrotropic and lactotropic secretion during prolonged calcitriol administration.

The stimulating effect of calcitriol, administered in the dose of 3 micrograms/day for four days, on the thyrotropic and lactotropic secretion has been proved in earlier studies in healthy humans. The present study was undertaken to confirm or eliminate the stimulatory action of the drug using increasing dosages of 0.75-1.50 micrograms/day for one month. In spite of the fact, that the biologically efficient levels of calcitriol were attained (confirmed indirectly by the rise of urinary calcium excretion, p less than 0.01), the stimulating effect of calcitriol on the basal and TRH induced thyrotropic and lactotropic secretion has not been manifested. In conclusion, the clinical importance of stimulating effect of calcitriol on the thyrotropic and lactotropic secretion is neglected, if only commonly accepted therapeutic dosages up to 1.50 micrograms/day are used.

Adult↗
PubMed1992

[Medullary carcinoma of the thyroid gland. Personal experience].

The authors present their experience with the diagnosis and treatment of medullary thyroid carcinoma (MTC) in a group of 175 patients in the records of the RI in Motol. From the above number 106 are alive, 69 of the patients who died were diagnosed at the time of the clinical manifestation of the disease, frequently an advanced stage of the disease. Of the living patients one third was treated by total thyroidectomy after active screening. MTC accounts under our conditions in recent years for 8.6% of all thyroid malignancies. The familial variant with autosomal dominant heredity accounts for 26.5% of the above number. Within the framework of the familial variant the most frequent finding is non-MEN MTC, only 30% MTC are part of the MEN 2A or MEN 2B syndromes. MTC in childhood belongs practically always to the familial variant. At present the authors' group comprises 13 children and adolescents under 18 years, incl. one boy with the MEN 2B syndrome who succumbed to the disease. In 8 children based on active screening total thyroidectomy was indicated, incl. 5 patients were by histological examination only hyperplasia of the C-cells, i.e. a precancerous condition, was detected. After operation repeatedly in all these patients the level of immunoreactive calcitonin is low which indicates an excellent prognosis. The authors draw attention to the importance of active screening in families of all direct relations of the patient where MTC was diagnosed. Complete removal of thyroid tissue at the time of hyperplasia of C-cells or the presence of tumourous microfoci has a marked positive effect on the subsequent fate of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

[Iodine status and incidence of thyropathies in the Czech population].

Based on clinical experience on the rising incidence of some thyropathies in our population, the authors examined a random sample of the Prague population. They assessed and evaluated iodinuria, the sonographic finding of the thyroid gland, the palpation finding of the thyroid and a clinical examination which comprised a detailed case-history (a questionnaire checked during the examination) and a clinical and anthropometric examination. The results indicate that iodinuria (which reflects the iodine intake) reaches the recommended optimum (above 150 micrograms iodine/l) only in 11.4% of boys, 14% men, 6.3% girls and 5.4% women. A quite inadequate intake (less than 50 g iodine/l) was recorded in 13.2% boys, 15.2% men, 17% girls and 33.1% women. When evaluating the thyroid volume, an enlarged volume is found in 20.4-58.3% and on evaluation by palpation pathological changes are found in a considerable proportion of the examined population. The findings suggest that the iodine supply of the Prague population is inadequate and the incidence of abnormal findings on the thyroid gland is high. It will be necessary to verify these findings in other random population samples from other localities. If the adverse position will be confirmed, this will call for an urgent solution, i.e. a better iodine supply of the population.

Adolescent↗
PubMed1992

[Thyroid gland antibodies. Methods and clinical significance].

The author presents a brief account of the clinically most important antibodies against thyroid antigens (against thyroglobulin, against the microsomal fraction or thyroid peroxidase, against thyroid hormones and against TSH receptors). He describes the main ways of their assessment in serum and evaluates the practical contribution of their estimation or detection in clinical diagnostic practice concerning endocrinopathies. Usually these estimations are only auxiliary and do not replace functional thyroid tests. Antibodies against thyroglobulin and against the microsomal fraction are found most frequently (and in the highest concentrations) in thyropathies with an assumed autoimmune component, in particular in lymphocytic thyroiditis. The low specificity (they are as a rule present also in other thyroid diseases and also in clinically eufunctional subjects with and without goitre) due to the relatively low prevalence reduce the diagnostic value of the examination. The examination of antireceptor antibodies is important, in particular in the diagnosis of immunogenic hyperthyroidism. The prevalence of antibodies against thyroid hormones is low and their detection serves about all to elucidate cases where the patient's clinical status is not in agreement with assessment of thyroid hormones.

Autoantibodies↗
PubMed1992

Epidermal growth factor (EGF) in serum of patients with differentiated carcinoma of thyroids.

Serum levels of epidermal growth factor (EGF) were investigated in 31 patients with differentiated carcinoma of thyroid. Patients with carcinoma had significantly decreased basal levels of serum EGF, however this decrease in serum EGF occurred only in the group of patients which had been evaluated at an interval of six weeks after ablation of residues of normal thyroid with radioiodine. In patients that had been treated with radioiodine for cancer this decrease was not observed. The change in serum EGF was not dependent on thyroidal function and did not correlate with the serum thyreoglobulin level. It is presumed that decreased serum EGF is a consequence of functional changes of platelets after whole body irradiation at ablative dose of radioiodine.

Adult↗
PubMed1992

[Determination of serum calcitonin using a non-commercial RIA method].

A radioimmunoanalytical determination of the immunoreactive calcitonine in the humen serum was worked out using the authors' own specific antiserum, the preparation and properties of which are reported in the present paper. The precision and reliability of the analytical procedure is within the usual limits (the intraserial variation coefficient was 8.6%, the calculated sensitivity was 6 pg/ml). The reported procedure was employed to determine calcitonine in a larger number of patients who were examined because of suspected medullar carcinoma of the thyroid gland and in patients suffering from other thyropathies. The results are discussed from the viewpoint of heterogeneity of calcitonine in the circulation.

Calcitonin↗
PubMed1991

Urinary iodine and the state of the thyroid gland in Czech children.

In 1988 the authors examined by palpation a total of 978 13--14-year-old children (490 boys and 488 girls) from two areas with a different endemic incidence of goitre (Sedlcany area high endemic, Príbram area low endemic). By palpation in this group a non-palpable thyroid gland was found in 48.2% boys and 33.2% girls. Type 1A in 44.9% boys and 50.0% girls, type 1B in 6.5% boys and 14.8% girls and type 2 in 0.3% boys and 2.0% girls. From this basic group by random selection a representative group of 200 children was selected where the following were assessed: urinary iodine/g creatinine, T3, T4, TSH and the volume of the thyroid gland. Urinary iodine in children from the Sedlcany area: boys 74.98 +/- 52.57 micrograms I/g cr, girls 75.36 +/- 77.05 micrograms I/g cr, children from the Príbram area: boys 55.0 +/- 23.36, girls 58.0 +/- 30.24 micrograms I/g cr. The difference between urinary iodine in boys from the two areas is significant (P < 0.05). The prevalence of optimal urinary iodine (i.e. 101-150 micrograms I/g cr) was in the Sedlcany area 6--13%, in the Príbram area 2.5-8.0% (girls, boys). The difference between areas was not significant. Volume of the thyroid gland in the Sedlcany area: boys 7.20 +/- 2.26 ml, girls 8.0 +/- 2.66 ml, in the Príbram area: boys 7.18 +/- 3.01 ml, girls 7.79 +/- 2.63 ml. The prevalence of children with a volume of the thyroid gland above 10 ml in the Sedlcany area was 20% in boys and 21.6% in girls. In the Príbram area 18.4% in boys and 17.5% in girls. The difference between areas was not significant. T3 in the Sedlcany area in boys: 2.43 +/- 0.53, in girls 2.42 +/- 0.51 nmol/l, in the Príbram area in boys 2.61 +/- 0.50, in girls 2.53 +/- 0.62 nmol. The difference between areas is not significant. T4 in the Sedlcany area in boys: 132.3 +/- 26.39 nmol/l, in girls: 132.92 +/- 26.77 nmol/l, in the Príbram area in boys: 126.7 +/- 23.89 nmol/l, in girls 147.8 +/- 40.2 nmol/l. The difference is significant in girls (P < 0.05). TSH Sedlcany area in boys: 1.62 +/- 0.67 mU/l, in girls 2.07 +/- 0.72 mU/l in the Príbram area in boys: 1.77 +/- 0.95 mU/l, in girls 2.10 +/- 1.25 mU/l. The difference is not significant. The prevalence of elevated T3 levels (above 3.0 nmol/l) in the Sedlcany area was 7.4% in boys and 8.9% in girls, in the Príbram area 15.4% in boys and 14.0% in girls. The difference is not significant.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1991

Application of non-commercial methods for estimation of immunoreactive serum calcitonin in clinical practice (comparison of two methods).

The authors compared the results of two radioimmunological methods for the estimation of immunoreactive calcitonin in human serum. Parallel with the commercial RIA kit the estimation was made by the authors' own modification of this process with their own specific antiserum and radioligand prepared in the laboratory. The results in a large group of patients with medullary carcinoma of the thyroid gland (MCT) in different stages of the disease revealed that although the values obtained by the two methods differ, there is a statistically significant correlation between the values and the clinical evaluation is also comparable.

Calcitonin↗
PubMed1990

[Beta-adrenergic receptors and cAMP production in the lymphocytes of patients with differentiated carcinoma of the thyroid gland during hypothyroidism and euthyroidism].

Beta-adrenergic receptors and production of cyclic adenosine monophosphate (cAMP) was investigated in peripheral lymphocytes of patients with differentiated thyroid carcinoma in hypothyroidism and euthyroidism, following therapy with 131I and suppression with thyroid hormones. After 131I therapy of patients with differentiated thyroid carcinoma and suppression by means of thyroid hormones, when the patients became euthyroid, the authors found a significantly lower maximal binding capacity Bmax on lymphocytes, as compared with the same patients before radiotherapy when the patients were hypothyroid. The basic cAMP content in patients with euthyroidism was higher, as compared with hypothyroid patients, the difference being at the borderline of significance (p less than 0.06). In vitro stimulation of cAMP formation by lymphocytes using the beta-adrenergic agonist isoprenaline was similar in hypo- and euthyroid patients and did not change in the course of treatment. When expressed in per cent, the stimulation of cAMP formation during euthyroidism was rather lower. Stimulation of cAMP formation by forskoline, an activator of adenylate cyclase was significantly higher in euthyroidism. Simultaneous addition of isoprenaline and forskoline to the incubation medium with lymphocytes produced an additive effect with markedly higher stimulation in euthyroidism. The reduced maximum binding capacity for 3H-dihydroalprenolol (3H-DHA) in euthyroid patients is discussed with regard to the probable influence of the basic disease, participation of radiation and the possible influencing of the immune system on changes in the number and activity of the patients' receptor system.

Adenocarcinoma↗
PubMed1990

Postnatal appearance of uncoupling protein and formation of thermogenic mitochondria in hamster brown adipose tissue.

Brown adipose tissue of developing hamster was characterized by western blotting, enzyme activity measurements and immunoelectron microscopy. During the first postnatal week the tissue contained significant amounts of differentiating mitochondria and comparable quantities of active cytochrome oxidase and ATP synthase. The uncoupling protein appeared on the 7/8th day and its specific content increased 80-times between day 8 and day 17. In parallel, the specific content and activity of cytochrome oxidase increased 3-times but ATP synthase decreased 2-times. The total content of uncoupling protein and of cytochrome oxidase in interscapular brown adipose tissue increased 360- and 11-times, respectively. Analysis of isolated mitochondria showed that the observed differences result mainly from changes of the enzymic equipment of the mitochondrial membrane. During the same interval, propylthiouracil-insensitive "type II' thyroxine 5'-deiodinase activity in brown adipose tissue increased 10-times. It was concluded that the thermogenic function of the hamster brown adipose tissue develops after the first postnatal week due to highly differentiated synthesis of mitochondrial proteins leading to replacement of preexisting, uncoupling protein-lacking nonthermogenic mitochondria by thermogenic ones, similarly as shown in brown adipose tissue of the embryonic mouse and rat (Houstĕk, J., et al. (1988) Biochim. Biophys. Acta 935, 19-25).

Adipose Tissue, Brown↗
PubMed1990

Morphological changes in the human thyroid gland cultivated in continual flow system.

In the present pilot study, the human thyroid gland tissue was cultivated under continuous culture conditions in the culture chambers of the ACUSYST-S system to determine morphological changes as well as the secretion of thyreoglobulin (Tgl) and thyroid hormones. After 24 hours of cultivation the follicular structure of the tissue was preserved in peripheral parts only, and there were regressive changes in the epithelium center. After 72 hours the regressive changes appeared in isolated follicles only; the size of the follicles increased, the height of the follicular epithelium decreased and there were macrophages present with phagocytized cell debris. After 144 hours disintegration of epithelia took place in the centre, while at the periphery the original follicles survived and very tiny new follicles formed, consisting of only 6 to 8 cells each and surrounding in section the homogeneous colloid. The parenchyma picture suggests a possibility of functional regeneration as an expression of adaptation to the conditions newly arisen during cultivation in a culture chamber. There was no significant influencing of the thyroid hormone secretion during cultivation. On the other hand, the Tgl secretion decreased throughout cultivation.

Culture Media↗
PubMed1990

[Changes in magnesium and ionized calcium serum levels in disorders of glucose tolerance].

In a group of 58 subjects with a strictly defined glucose tolerance (38 normal--nGT, 10 impaired glucose tolerance--pGT, 10 type II diabetics treated by diet) the authors investigated the mutual relationship between changes in the blood sugar level and insulin serum level in relation changes of calcium, ionized calcium, magnesium and total proteins. In addition to expected differences in the native blood sugar level and insulinaemia, the authors found in pGT group in reduction of ionized calcium and magnesium on fasting. In the course of the oGTT in pGT group there is a rise of ionized calcium and magnesium and thus the changes, as compared with the initial value, differ significantly from changes in subjects with a normal glucose tolerance and in type II diabetics. The differences in the pattern total calcium are less marked, the changes of total protein did not differ. Evaluation of correlations revealed a only significant relationship between the change of ionized calcium and blood sugar level after 120 mins, in DM II. The findings suggest a different calcium and magnesium metabolism after a glucose load in subjects with an impaired glucose tolerance. It is not clear whether a cause of the disorder is involved or a possible compensatory mechanism. The clinical impact will have to be examined.

Calcium↗
PubMed1990

[Cardiac function and adrenergic regulation in incipient hyperthyroidism].

The authors investigated in 14 euthyroid women the action of triiodothyronine administered for 7 days, 100 micrograms per day. It was revealed that after the administration of triiodothyronine the duration of the preejection period of the systole was reduced as well as the index of the preejection period and the index of the electromechanical systole, and the weight declined. At the same time the authors recorded a drop of the plasma noradrenaline and adrenaline level, of the serum cholesterol and thyroxine concentration. The serum triiodothyronine level increased and correlated inversely with the duration of the preejection period. Triiodothyronine administration had no effect on the heart rate, Q-Kd interval, blood pressure and plasma concentration of cyclic adenosine monophosphate. The authors conclude from the findings that in triiodothyronine-induced hyperthyroidism the first cardiac effect of the administered hormone is enhanced contractility of the heart, this change being due to the direct effect of triiodothyronine not mediated by catecholamines.

Adolescent↗