Search PubMed⌕ Search

Biomedical subjects

P Langer

Publications and source records attributed to P Langer.

At least 127 records · Page 7Linked to original sources
PubMed1989

Studies and reevaluations of some aspects on thyroid function after superior cervical sympathetic gangliectomy in rats.

The results of 11 experiments in a total of 571 rats (initial body weight of 150-250 g) are reported and some findings differing from those by others are discussed. It was repeatedly found that the animals after bilateral or even unilateral superior cervical sympathetic gangliectomy (GX) did not gain body weight during the first week after surgery. Though they started to grow later, for several weeks their body weight remained significantly less than that of sham operated controls (SH). Though such phenomenon has not yet been described, it may well explain the increase of thyroid weight (as expressed per body weight) after gangliectomy alone or combined with antithyroid drug treatment or hypophysectomy as described by others. It was suggested that such changes may depend on general metabolic changes resulting in a striking inhibition of body weight gain rather than on some specific effect of GX on the thyroid. This view was supported by evaluating the data on absolute and relative thyroid weight from 4 experiments in a total of 265 animals. The level of thyroxine (T4) and thyrotropic hormone (TSG) was repeatedly found to be significantly decreased after GX for until about 72 h and 24 h after surgery, respectively, which was in agreement with the data reported by others. However, the onset of such decrease was repeatedly found to appear at 6 or 8 h after surgery (in one experiment even at 3 h after surgery) which is also contrasting to the onset of T4 decrease at 14 h after surgery as found by others who suggested a correlation of such thyroid depression with a depletion of noradrenaline from the thyroid and may be even from median eminence. In these experiments, however, a decrease of T4 level was found several hours before the depletion of noradrenaline from the thyroid which appeared at 12 h after surgery and remained at similar level until 40 days, while no remarkable changes of that were found in SH animals (with the excretion of slight increase after 24 h). Between about 4 and 40 days after surgery no significant changes in T4 and TSH levels after GX were found as compared with SH animals is in agreement with others.4+n one experiment the increase of T4 at 2 h after TRH injection, resulting apparently from the effect of endogenous TSH, was significantly inhibited in GX animals at 8 days after surgery, while in other experiments (at 8 and 40 days after surgery) no difference in T4 level increase was found in GX animals as compared with SH ones. In general, it may be suggested that superior cervical sympathetic gangliectomy may result in some temporary and perhaps transient changes in pituitary-thyroid function in rats.

Animals↗
PubMed1988

Thyroid volume of East Slovakian adolescents determined by ultrasound 40 years after the introduction of iodized salt.

Thyroid volume was examined by ultrasonography in 207 boys and 220 girls aged 15-16 years from East Slovakia and it was found that 49.3% of the boys and 52.3% of the girls had thyroids between 10 and 15 ml. These thyroid volumes resemble those found in school children from areas of mild iodine deficiency (e.g. FRG) and are twice as large as those reported from Sweden, where iodine intake is sufficient. The findings were compared to these reported by others in 1949-53 before the introduction of iodine prophylaxis. It may be concluded that 40 years of goiter prophylaxis with iodized salt, though resulting in urinary excretion of approximately 100 micrograms/24 hr (as found by others in 1984), abolished large and medium size goiters in adolescents and decreased a prevalence of goiter grade I to about 25 percent, but appeared still to be insufficient to prevent goiter grade I completely.

Adolescent↗
PubMed1988

Effect of ethanol and linoleic acid on changes in biliary excretion of iodothyronines possibly related to thyroxine deiodination in rat liver.

Groups of male rats weighing about 350 g were inserted polyethylene tubings into bile duct and femoral vein under pentobarbital anesthesia. Several iodothyronines (i.e. T4, T3, rT3, 3,5-T2, 3,3'-T2 and 3',5'-T2) were estimated in 2-hr portions of bile with the aid of specific radioimmunoassay. After the infusion of ethanol (0.3 ml/hr/rat for 4 hr) an increase of biliary excretion of rT3 and a decrease of 3,5-T2 was found as compared to controls. When 5 mg linoleic acid was added to 1.2 ml ethanol, the increase of rT3 was significantly higher than that after ethanol only and, in addition, significant increase of 3',5'-T2 excretion was found. It was concluded that both ethanol and unsaturated fatty acids may inhibit 5'-monodeiodination in the liver and that unsaturated nonesterified fatty acids may exert such effect even when administered intravenously without underlying metabolic disorders.

Animals↗
PubMed1988

Effect of acute cold exposure and insulin hypoglycemia on plasma thyrotropin levels by IRMA in healthy young males.

Thyrotropin (TSH) levels in plasma were estimated with the aid of immunoradiometric assay in two groups of healthy male subjects aged 21-22 years in two experiments: 1. acute (30 min) exposure to 4 degrees C in a cold room; 2. insulin (0.01 U per kg i.v.) hypoglycemia at room temperature and at 55 degrees C. Immediately after cold exposure a decrease of TSH level was found (P less than 0.01), while no changes were observed during 30 min exposure. After insulin injection a significant decrease (P less than 0.05 to less than 0.001) of TSH level was found at 45 to 120 min irrespectively of the ambient temperature. In addition, increased levels of noradrenaline and decreased levels of growth hormone after cold exposure are presented.

Adult↗
PubMed1988

Iodothyronines in human bile.

Bile was collected from 7 patients after cholecystectomy with routine T-tube drainage of bile duct postoperatively. In all patients reported, the total volume of bile collected was more than 500 ml which was considered to be close to the volume of bile excreted by the liver during the 24 h collection period. The excretion of total thyroxine (T4), triiodothyronines (T3 and rT3) and diiodothyronines (3,3'-T2, 3,5-T2 and 3'.5'-T2) was estimated with the aid of specific radioimmunoassay described previously. It was found that the total amount of T4 corresponded to its content in about 100 ml plasma, while corresponding figures for triiodothyronines were about 1000-1500 ml and these for diiodothyronines about 10-15 liters. It was concluded that in man the biliary excretion of iodothyronines appears to be of much less importance for their total body balance than in rats.

Aged↗
PubMed1987

Delayed changes of plasma level and biliary excretion of several iodothyronines after a single administration of low doses of thyroxine in rats.

Male Wistar rats were injected i.p. 2.5 or 5.0 micrograms thyroxine (T4) and the level of several iodothyronines and TSH in plasma or biliary excretion of iodothyronines were estimated by radioimmunoassay in groups of animals in various intervals up to 144 hr after the administration. In general, two peaks in the plasma level and biliary excretion of iodothyronines were found: first one within 24 hr and a delayed second one between about 48 and 72 hr after the administration. It was concluded that the first peak may correspond to the metabolic changes in fast tissue pools, while a second one might reflect some delayed iodothyronine metabolic steps in slow tissue pools after a bolus injection of T4.

Animals↗
PubMed1987

Studies on in-vivo capacity of thyroxine deiodinating system in rat liver: biliary excretion of several iodothyronines after increasing loading doses of thyroxine.

Eighteen male rats were inserted with polyethylene tubings into bile duct and femoral vein and two rats each were injected a series of doses from 5 to 1280 micrograms L-thyroxine into a venous cannula. The bile was collected for three subsequent 2-hr periods and the excretion of total thyroxine (T4), triiodothyronines (T3 and rT3) and all diiodothyronines (3,3'-T2, 3,5-T2 and 3',5'-T2) was estimated as well as that of conjugated T4 and T3. The excretion of all compounds was considerably increased as early as within the first 2-hr period. Almost linear dose-response relationship was found between the dose of T4 and its biliary excretion up to the dose of 640 micrograms, only smaller increase being observed after 1280 micrograms T4. Similar relationship was found also in the excretion of diiodothyronines, while that of triiodothyronines after 1280 micrograms T4 was slightly less than after 640 micrograms T4. The excretion of rT3 was consistently about twice as high as that of T3. The data on diiodothyronine excretion suggested a preferential conversion of rT3 to 3',5'-T2 and that of T3 to 3,5-T2 over that to 3,3'-T2. The ratio of 3,5-T2/T3 after different doses of T4 was about 2--4 times higher than that of 3',5'-T2/rT3 suggesting the higher deiodination rate of T3 than that of rT3.

Animals↗
PubMed1987

Dual dose-related action of peripherally administered morphine on cold-stimulated thyrotropin secretion in male rats.

Cold-induced increase of thyrotropin (TSH) release was found to be inhibited after 10 or 20 mg/kg morphine sulfate (MO) injected intraperitoneally 30 min before the transfer of adult male rats from 30 to 4 degrees C for 60 min (i.e. 90 min before sacrifice). In contrast, lower doses of MO such as 2.5 and 5 mg/kg were found to stimulate the cold-induced TSH release under the same conditions. Such a cold-induced TSH release stimulated by lower doses of MO was found to be inhibited by intraperitoneal injection of 2 or 4 mg/kg naloxone (NX) 30 min before MO injection (i.e. 120 min before sacrifice) in a dose-dependent manner, while the same doses of NX were without effect on the levels of TSH after higher doses of MO. It is suggested that these effects may depend on different sensitivities of various hypothalamic loci involved in mediating either a stimulation or inhibition of TSH release.

Animals↗
PubMed1987

Effects of alpha 1- and alpha 2-adrenoceptors on basal and adrenaline mediated insulin secretion in rats.

Groups of male rats were injected phentolamine, prazosin or yohimbine and infused with saline or adrenaline for 4 h under pentobarbital anesthesia. Blood samples were taken at 30 min intervals during the infusion, the isovolemia being maintained by replacing the blood volume with the blood obtained from normal donor animals. Plasma glucose and insulin levels were estimated. In saline infused animals a severalfold increase in plasma insulin levels was found after pretreatment with phentolamine, while such increase after prazosin or yohimbine was much less, though significant. In adrenaline infused animals the increased insulinemia after phentolamine pretreatment was still more remarkable than in those infused saline. After prazosin treatment, however, no changes in insulinemia were found during adrenaline infusion, while yohimbine pretreatment resulted in a significant insulin increase in similarly infused rats. It is concluded that alpha 2-receptors apparently play a major role in mediating inhibitory effects of adrenaline on insulin secretion. However, even some participation of alpha 1-receptors in the complex regulation of insulin secretion in vivo cannot be excluded, since the effect of phentolamine pretreatment on either basal or adrenaline induced insulinemia was higher than that of yohimbine, though a higher molar dose of the latter was used. In addition, no changes in insulinemia were found during the infusion of adrenaline only which may be explained by a prevailing effect of inhibitory alpha-adrenoceptor tone over a stimulatory beta-adrenoceptor tone under the conditions of unblocked adrenoceptors.

Animals↗
PubMed1986

Ligand binding to heme proteins: relevance of low-temperature data.

Binding of carbon monoxide to the beta chain of adult human hemoglobin has been studied by flash photolysis over the time range from about 100 ps to seconds and the temperature range from 40 to 300 K. Below about 180 K, binding occurs directly from the pocket (process I) and is nonexponential in time. Above about 180 K, some carbon monoxide molecules escape from the pocket into the protein matrix. Above about 240 K, escape into the solvent becomes measurable. Process I can be observed up to 300 K. The low-temperature data extrapolate smoothly to 300 K, proving that the results obtained below 180 K provide functionally relevant information. The experiments show again that the binding process even at physiological temperatures is regulated by the final binding step at the heme iron and that measurements at high temperatures are not sufficient to fully understand the association process.

Carbon Monoxide↗
PubMed1985

Thyroid hormones in rats during long-term cold exposure and hypometabolic effect of reverse triiodothyronine on adrenaline induced thermogenesis.

One-day cold exposure to 5 degrees C induced temporal increase of reverse-triiodothyronine (rT3), triiodothyronine (T3) and thyroxine (T4) concentrations in the blood of rats (by 151%, 91% and 107%, respectively). The levels of all thyroid hormones remain elevated for at least 10 days of cold exposure. The injection of rT3 (330 micrograms kg-1 s.c.) inhibited the resting and adrenaline stimulated metabolism 1-3 days after application independently from the thyroid status of the animals. Since the hypothermic effect of rT3 occurred in thyroidectomized rats, it was concluded that rT3 acted primarily on peripheral, tissues, rather than on the thyroid.

Animals↗
PubMed1985

Acute changes of iodothyronine excretion by bile after a single and repeated administration of dexamethasone in rats.

Bile was collected from cannulated bile duct under pentobarbiturate anesthesia and the excretion of several iodothyronines was estimated with the aid of radioimmunoassay as described previously. The excretion of triiodothyronine (T3) was significantly decreased between 4 and 6 h after a single injection of 20 and 40 mg kg-1 dexamethasone (DEX), while no changes in the excretion of thyroxine (T4) and reverse triiodothyronine (rT3) were found. In another experiment a decrease of T3 excretion was observed together with an increase of rT3 excretion and of T4/T3 and rT3/T3 ratio between 9 and 11 h after a single injection of 0.75, 1.5 and 3.0 mg kg-1 DEX, the differences being in most cases significant as compared to controls. In the same experiments a dose related increase of excretion of 3,3'-diiodothyronine (3,3'-T2) and 3,5-diiodothyronine (3,5-T2) was found, while the excretion of 3',5'-diiodothyronine (3',5'-T2) decreased with dose of DEX. Similar results were observed even after the administration of 1.5 and 3.0 mg kg-1 DEX for 5 days. In addition, the level of rT3 in serum was significantly increased at 9 h after a single dose of 3.0 mg kg-1 DEX and after 5 days administration of 1.5 and 3.0 mg kg-1 DEX. The data support a previous view that the changes in biliary excretion of iodothyronines are closely related to deiodinating metabolism of T4 in the liver and are expressed earlier and more remarkably than these in their plasma level.

Animals↗
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↗