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Biomedical subjects

V Strbák

Publications and source records attributed to V Strbák.

At least 55 records · Page 3Linked to original sources
PubMed1989

Incidence of thyroid hormone autoantibodies in patients with thyroid diseases with respect to diagnosis, other types of autoantibodies, duration of disease and treatment.

Thyroid hormone autoantibodies (THAA] were estimated in a total of 149 patients (139 women and 10 men) with various thyroid diseases. THAA were found in a total of 22 patients (all women), i.e. 14.7%. In 8 of them both T4Ab and T3Ab were found, while T4Ab only were found in 4 patients and T3Ab only in 10 patients. The highest incidence of THAA was found in patients with diffuse lymphocytic thyroiditis (i.e. 11 cases out of a total of 64 patients) and similarly high incidence was in patients with suspected autoimmune goiter but without thin needle biopsy (i.e. 5 cases out of a total of 21 patients). If only the patients with manifested or silent hypothyroidism were selected, T4Ab were found exclusively in this group, while the incidence of T3Ab was 3 times higher as that in patients without hypothyroidism. Though the incidence of T4Ab in patients with positive antithyroglobulin and antimicrosomal antibodies was 3 times higher than in negative ones, the difference was not significant. No correlation was found between the incidence of THAA on one hand and the duration of disease, the duration of treatment and the drug used for treatment on the other. However, a significant correlation was found between the incidence of THAA and the presence of goiter (P less than 0.05).

Autoantibodies↗
PubMed1988

Thyroid hormone levels in cow maternal and fetal sera during last trimester of pregnancy.

Thyroid hormone levels were studied in 51 paired pregnant cow and fetal calf serum samples (fetal age 7-9 months). Thyroxine and rT3 levels were substantially higher and those of T3 distinctly lower in calf fetuses as compared to respective mothers. An increase of T3 has been detected in calf sera at the fetal age 8 to 8.5 months. These results suggest some prenatal maturation of thyroxine metabolism in the calf.

Animals↗
PubMed1987

Effects of sauna and glucose intake on TSH and thyroid hormone levels in plasma of euthyroid subjects.

The effect of sauna on thyroid function parameters and its modification by glucose was studied in young euthyroid male volunteers. A 30-minute stay in sauna resulted in an increase in plasma TSH; the response was exaggerated if glycemia had been increased by oral glucose intake at the beginning of the experiment. Plasma rT3 also increased in sauna, this response was, however, blunted by the higher glycemia. TSH response to sauna was definitely present in young men (aged 20 to 25) and absent in middle-aged ones (50 to 55). To explore the mechanism of the effect of increased glycemia, TRH tests were performed and dopamine infusions were administered with and without glucose pretreatment. Increased glycemia did not affect TSH and T3 response to TRH in young volunteers; however, 90 minutes after the administration, plasma rT3 levels were significantly lower in glucose pretreated subjects than in those receiving TRH injections after water pretreatment. Simultaneous infusion of glucose prevented the inhibitory effect of dopamine infusion on plasma TSH. It was concluded that glucose directly modulates the effect of sauna on plasma TSH at a suprapituitary level, while the inhibiting effect of glucose on plasma rT3 response to sauna and TRH is probably mediated by the insulin effect on thyroid hormone metabolism.

Adult↗
PubMed1987

Biological activity of TRH thionalogue and its diastereoisomers.

Binding affinity and TSH-releasing activity of [Prot3] TRH analogue (L-pyroglutamyl-L-histidyl-L-proline thioamide), TRH and their LDL and LLD diastereoisomers were compared in rats. Binding affinity and dose-related increase of TSH secretion were similar for both [Prot3] TRH and TRH. Moreover, similar effect of both peptides on sleeping time and motoric activity of rat was found. Substitution of L- for D-amino acids of TRH and [Prot3] TRH decreased the binding affinity and TSH-releasing activity as well. It was concluded that [Prot3] TRH analogue is as active as native TRH.

Animals↗
PubMed1987

[Leprechaunism].

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Abnormalities, Multiple↗
PubMed1987

Exchange transfusion in premature newborns: effect of maturity on thyrotropin and thyroxine responses.

The effects of exchange transfusion on plasma T4 and TSH were studied in two groups of premature newborns to evaluate the effect of maturation on the reactivity of the pituitary-thyroid axis. In newborns with a birth weight between 1900-2500 g (gestational age 35.4 +/- 0.45 weeks) the responses of both hormones were essentially similar to those reported previously for mature newborns (a profound decrease during the procedure and an increase 24 h later). In a group of newborns with a birth weight below 1900 g (average 1673 +/- 55, gestational age 32.7 +/- 0.72 weeks), however, the secondary increase in plasma T4 at 24 h after the procedure was absent. At this time both T4 and TSH levels were significantly lower than in those in heavier newborns. It is concluded that the ability to respond to exchange transfusion by an increase in plasma thyroxine at 24 h after the procedure matures at the gestational age between 32 and 35 weeks.

Exchange Transfusion, Whole Blood↗
PubMed1986

Role of thyrotropin-releasing hormone in thyroid-stimulating hormone and growth hormone regulation during postnatal maturation in female Wistar rats.

The role of endogenous thyrotropin-releasing hormone (TRH) in the control of pituitary thyroid-stimulating hormone (TSH) and growth hormone (GH) secretion was studied during postnatal maturation in female Wistar rats. Half of the sucklings in each litter was treated intraperitoneally with either specific rabbit antiserum against TRH or normal rabbit serum (0.1-0.3 ml according to age). All animals were decapitated after 2 h. The presence of anti-TRH activity was checked as a binding of labelled TRH with plasma of the experimental animals. Immunoneutralization of endogenous TRH resulted in a decrease of plasma TSH in 3- to 15-day-old female pups as compared to control littermates. No effect of TRH antibody injection was seen at the ages of 1, 21, 30 and 70 days despite the presence of excess antibody in the plasma. A profound effect of TRH antibody on plasma TSH was seen again at the age of 100 days. Plasma GH in the same animals exhibited a paradoxical increase after TRH immunoneutralization at the age of 5 and 8 days, a decrease was found at the age of 21 days. It was concluded that hypothalamic TRH control of TSH secretion matures early in Wistar rats. Hypothalamic secretion of TRH at the ages of 1, 21, 30, and 70 days is low and(or) its role in TSH regulation is masked by other regulating factors. TRH may play a dual role in the regulation of GH secretion during the postnatal period.

Aging↗
PubMed1986

Human milk does not degrade TRH.

We have found previously that TRH is accumulated in rat milk in biologically active form. TRH was reported to be present in high concentrations in human milk too. These findings together with the absence of TRH degrading activity in plasma of newborns suggest a possible physiological role of the neurohormone coming from milk. We studied, therefore, TRH degrading activity of human milk. TRH incubated in vitro with 100 microliters human milk (4 days and 4 months after delivery) in 0.01 mol l-1 phosphate saline buffer (pH 7.6) with 1% gelatine (total volume 0.3 ml) at 37 degrees C was not degraded during 2 hours as revealed by specific RIA. The addition of the same amount of milk to adult human plasma did not affect intensive TRH degradation. We conclude that human milk does not contain TRH degrading enzymes nor their inhibitors.

Humans↗
PubMed1986

Effect of breast-feeding on infant thyroid activity: 3 year follow up--longitudinal study.

The effect of breast-feeding on serum thyroid hormones and TSH was studied in a longitudinal study from birth up to 3 years. T4 was found to be significantly higher in breast-fed than in weaned infants at the age of 4 and 6 months and so was rT3 at the age 4 months. The body weight of breast-fed girls at the age 4 and 6 months was lower than that of formula-fed ones. Breast-feeding at the age 9 months resulted in a decreased serum TSH. Serum T3 of infants weaned before the end of the first week of life was higher than in other groups of infants at the age of 10 weeks. Serum T4 of children 1-2-year-old correlated positively with the age at weaning, provided that they had been breast-fed at least for 60 days. Serum rT3 of 2-year-old children also correlated with the age of weaning. Serum TSH at the age of 3 years was higher in children who had been weaned during first 60 days of life than in those weaned later. It is concluded that breast-feeding possess some immediate effects on thyroid function parameters. Some effects were still detected at the age of 1-3 years.

Age Factors↗
PubMed1985

Maturation of the inhibitory response of growth hormone secretion to ether stress in postnatal rat.

To study the maturation of inhibitory influences on growth hormone (GH) secretion the effect of ether stress on plasma GH levels was studied during postnatal ontogenesis in female rats. Ether stress did not affect plasma GH levels in 1-day-old pups. A distinct decrease of plasma GH was found in 3- and 9-day-old pups, and the response was prevented by treatment of 3-day-old animals with somatostatin antiserum. No effect of ether stress on plasma GH was noted in 12-, 15-, 18- and 21-day-old rats. Treatment of intact 12-day-old pups with the somatostatin antiserum increased plasma GH level under basal conditions. The inhibitory effect of ether stress on plasma GH was noted again at the age 30 days and in adult animals. It is concluded that the hypothalamus of 3-day-old rats is able to release enough somatostatin to inhibit GH secretion after stress. At the period 12-18 days a phase of pituitary refractoriness was noted: ether stress as well as TRH injection (our previous observation) fail to affect plasma GH in female pups, probably due to high somatostatin secretion under basal conditions and (or) low capacity of pituitary to release GH. It is suggested that regulation of GH secretion is not mature until after the 21st day of life.

Aging↗
PubMed1985

TRH analogue with C-terminal thioamide group: rapid degradation by plasma and its biological effects.

L-pyroglutamyl-L-histidyl-L-proline thioamide--([Prot3]TRH), a new TRH analogue, has been previously found to have the same binding affinity to adenopituitary receptors as well as TSH and alpha-MSH releasing activities as native TRH. In this paper we report also the same time course of TSH response after i.p. injection of this compound (10 micrograms kg-1) to rats. Binding affinity to specific receptors in rat amygdala, cortex (frontal lobes), hypothalamus, striatum (order according to decreasing affinity) of both peptides was also similar. In contrast to TRH, however, [Prot3]TRH in doses 0.5 and 5 mg kg-1 i.p. did not affect sleeping time and breathing frequency in the rats during barbiturate anaesthesia. Surprisingly, human plasma degraded the new analogue much faster (T1/2 8.5 min) than native TRH (T1/2 30 min). [Prot3]TRH was also degraded faster in plasma of adult rats. Plasma of 6-day-old rat pups failed to degrade both peptides. It was concluded that the substitution of proline amide, for proline thioamide group in TRH molecule did not change binding affinity to receptors in the central nervous system, but decreased biological effectiveness in CNS and substantially decreased the resistance to degradation in human and rat plasma.

Animals↗
PubMed1984

TSH response to 30 min stay in sauna in the morning and during evening hours.

The response of plasma TSH to 30 min stay in sauna was compared in the morning and in the evening. Both in the morning and in the evening plasma TSH was significantly elevated after sauna, with more prolonged response in the evening. This difference resembles the different reactivity of TSH to exogenous TRH administration in various times of day.

Adult↗
PubMed1983

Thyroid hormones in milk: physiological approach--a review.

Reported values of the concentration of thyroid hormones in milk vary substantially. There are some doubts on the specificity of methods used for their estimation. We aimed, therefore, to study the effects of mother milk on thyroid function parameters in sucklings as well as at the effect of milk secretion on maternal thyroid. According to Fukuda et al. [1980] the lactation induces a hypothyroid state in the rat (high TSH, low thyroid hormones in maternal plasma). In our study the weaning of 18-day old rats resulted in gradual decrease of T4 in suckling plasma through 24 h followed with a transient thyroid activation. Thyroidectomy of lactating rats resulted in a transient decrease of T4 in sucklings. The difference in mother milk intake achieved by different litter size also affected the thyroid function of sucklings. The pups from small size litters (more milk consumption) had low thyroid secretion rate and low plasma TSH, while the level of T4 in plasma was high under a higher growth rate and accelerated overall maturation. All these results suggest an exogenous intake of thyroid hormones in suckling rat. We found that lactation in women resulted in lower T4 and higher TSH in plasma as compared to women who had interrupted their lactation. In the next part of our study more than 80 infants were longitudinally followed and sampled at birth (cord blood), at 2, 6 and 10 weeks and at 4, 6, 9 and 12 months. Only moderate differences were found at 4 months (high rT3) in breast fed infants and 9 at months (high T3 in plasma of infants weaned during the first week of life) when the data were evaluated according to the type of feeding. Thyroid activity of human milk was tested by feeding thyroidectomized rats with a diet containing human milk. Although plasma TSH was affected by such a diet, we did not detect any T4 and T3 in plasma of thyroidectomized rats which probably refects low calculated intake of hormones with the diet. We conclude that the lactation affects the thyroid economy of maternal organisms. Maternal milk definitely affects thyroid function parameters in the rat, while the effect on infant thyroid is more difficult to demonstrate.

Adolescent↗