Search PubMed⌕ Search

Biomedical subjects

I Barna

Publications and source records attributed to I Barna.

At least 19 recordsLinked to original sources
PubMed2001

Beta endorphin-like immunoreactivity in human aqueous humor and crystalline lens.

We measured the concentration of beta-endorphin (beta-End) in plasma, as well as in aqueous humor and crystalline lens removed during cataract surgery. beta-End was detected both in the aqueous humor and in the crystalline lens. The concentration of beta-End in the aqueous humor corresponded to almost the half of the plasma level (2.18 fmol/l and 4.55 fmol/l). Endogenous beta-End is presumed to enter the intraocular structures by passive diffusion.

Aged↗
PubMed2001

Oestrogen and vitamin D receptor (VDR) genotypes and the expression of ErbB-2 and EGF receptor in human rectal cancers.

Oestrogen/oestrogen receptor (ER) and vitamin D/vitamin D receptor (VDR) systems have been implicated in the pathogenesis of colorectal cancers. The expression of erbB-2 and epidermal growth factor receptor (EGFR) in colorectal cancers has been suggested to have diagnostic and prognostic significance. In our study, XbaI and PvuII polymorphisms of the ER gene and the BsmI polymorphism of the VDR gene were studied in 56 Caucasian patients with rectal cancer. The relationship between the ER and VDR genotypes and the expression of oncogenes was also investigated. The presence of the x allele of ER gene significantly correlated with the overexpression of the erbB-2 and EGFR oncogenes. Significantly increased erbB-2 expression was observed in patients with the VDR B allele. The XXbb allelic combination of the ER/VDR genes was associated with a significantly lower erbB-2 expression, whereas in the other genotypes significantly higher oncogene expression was seen. Our data raise the possibility that ER/VDR gene polymorphisms accompanied by variable oncogene expression might influence the pathogenetic processes of colorectal cancers.

Adult↗
PubMed2000

Radiodetoxified lipopolysaccharide fails to activate the hypophyseal- pituitary-adrenal axis in the rat.

Lipopolysaccharide (LPS) is known to raise the concentration of the circulating stress hormones such as ACTH, corticosterone and beta-endorphin. This effect of endotoxin is mediated by different immune system-released hormone-like factors (e.g. interleukins, tumor necrosis factor etc.). Gamma-ray irradiation of LPS alters its biological properties and results in a radiodetoxified LPS preparation with numerous beneficial effects and decreased toxicity. In this study we compared the neuroendocrine effects of a commercial LPS and our native and radiodetoxified LPS preparations in rats. Plasma ACTH, corticosterone and beta-endorphin levels were measured by specific radioimmunoassays 120 min after intraperitoneal LPS administration. Control animals were injected with saline. Results show a dramatic increase in all hormones after administration of commercial and our native LPS preparation. Hormone levels in saline-injected controls and radiodetoxified LPS-treated rats did not rise significantly. These results suggest that radio-detoxification disintegrated that part of the LPS molecule complex which is responsible for toxicity including an enhanced production of cytokines, which trigger the hypothalamo-pituitary-adrenal axis.

Adrenocorticotropic Hormone↗
PubMed1999

Alpha 2-adrenoreceptor subtypes regulate ACTH and beta-endorphin secretions during stress in the rat.

The effect of different alpha 2-adrenoreceptor subtype agonists and antagonists on adrenocorticotrop hormone (ACTH) and beta-endorphin release induced by ether stress was examined. Ether inhalation-induced ACTH and beta-endorphin increase was inhibited by i.c.v. administration of 30 micrograms but not 1 and 10 micrograms clonidine (alpha 2-adrenoreceptor agonist). I.c.v. oxymetazoline (alpha 2A-adrenoreceptor agonist; 1-10-30 micrograms) or the alpha 1-agonist methoxamine (100 micrograms/rat) failed to inhibit the stress-induced rise. Pretreatment with the alpha 1/alpha 2B.C-antagonist prazosin (0.5 mg/kg, i.p.) prevented the effect of clonidine on the ether stress, while the alpha 1/alpha 2A-antagonist WB-4101 (0.5 mg/kg, i.p.) was unable to counteract the inhibitory effect of clonidine. Prazosin alone had no effect on the ether-induced plasma ACTH and beta-endorphin elevation. These results suggest that noradrenaline in the central nervous system may inhibit the stress-induced hypothalamo-pituitary-axis and pituitary beta-endorphin activation via alpha 2B.C-adrenoceptor subtypes and prazosin may antagonize its effect on these receptors.

Adrenergic alpha-Agonists↗
PubMed1998

[The place of enalapril in the management of hypertension].

In Hungary the use of angiotensin converting enzyme inhibitor enalapril has emerged as one of the most important drugs in the treatment of hypertension. The aim of our study was to evaluate the antihypertensive effect of enalapril of Hungarian production in combination therapy and alone, according to sexes, to the body mass index, among smokers and non smokers as well as non diabetic and in patients with diabetes (IDDM and NIDDM). The diurnal blood pressure values were registered by a 24 hour ambulatory blood pressure monitor. During the 6 weeks of the enalapril therapy (n = 28) both the daytime (141/84 vs. 135/80 mmHg) and the night-time (130/78 vs. 124/72 mmHg) blood pressure values decreased; the increase of diurnal indices during the therapy (SI/DI 6/8% vs. 8/10) reflect the 24 hour long lasting effect of the drug. The body mass index had no influence on the efficacy of treatment. Our results indicate that enalapril manufactured in Hungary is an effective antihypertensive drug both in monotherapy and in combination, in both sexes (especially in men), irrespective of the body weight, in non-smokers and especially in smokers, in insulin dependent and in non-insulin dependent diabetes mellitus alike.

Antihypertensive Agents↗
PubMed1998

Characteristics of the proopiomelanocortin system in the outdoor-bred domestic gander. II. Seasonal and circadian rhythmicity; effect of ether stress and lipopolysaccharide administration.

The responsiveness of the POMC system to exogenous stimuli and the diurnal and seasonal rhythmicity of ACTH and beta-endorphin (beta E) in plasma were studied in outdoor-reared domestic ganders. Plasma levels of ACTH- and beta E-like immunoreactivities were determined by direct and specific radioimmunoassays. In the first series of experiments immunoreactive (ir) ACTH and beta E were measured in the plasma of male domestic geese after 5 min of ether stress and after administration of 2 micrograms/kg lipopolysaccharide (LPS). Both ir-ACTH and ir-beta E levels increased 5 and 10 min after ether inhalation, but the increase in the ir-beta E concentration was only half that of the ir-ACTH. The plasma ir-ACTH levels were elevated after 60 and 120 min but not after 90 min of LPS administration: ir-beta E levels were unchanged at all time points. In a second series of experiments blood samples were taken on 30 March. 16 June, 4 August, and 27 October. On these days diurnal samplings were performed at 02:00, 06:00, 10:00, 14:00, 18:00, and 22:00 h. A two-way analysis of variance showed significant diurnal and seasonal changes for both hormones and significant interaction between the diurnal and seasonal levels. The highest daily mean values of the plasma ir-ACTH and ir-beta E concentrations were measured in June. The maximum of the ir-ACTH level was at 10:00 h in March and August, but at 22:00 h in June and October. The changes in ir-beta E concentrations paralleled those of ir-ACTH, but the changes did not reach statistical significance in every case.

Administration, Inhalation↗
PubMed1998

Characteristics of the proopiomelanocortin system in the outdoor-bred domestic gander. I. ACTH and beta-endorphin levels in the brain, pituitary, and plasma.

Immunoreactive (ir-) adrenocorticotropic hormone (ACTH) and beta-endorphin (beta E) levels were determined in seven brain regions, in the three pituitary lobes, and in the plasma of the domestic gander by specific radioimmunoassays. In the brain regions studied the relative concentrations of ir-ACTH and ir-beta E were the highest in the mediobasal hypothalamus and in the paraventricular nucleus. There were lower levels of these peptides in the supraoptic nucleus, in the septum, and in the dorsal thalamus. Very low ir-ACTH and -beta E contents were found in the archistriatum and in the lobus parolfactorius. In the pars distalis of the pituitary gland the cephalic lobe contained about 10 times more ir-ACTH (3596 pmol/lobe) and 4 times more ir-beta E (867 pmol/ lobe) than the caudal lobe (383 pmol/lobe and 189 pmol/lobe, respectively). Sephadex G-50 chromatography of pooled cephalic and caudal lobe extracts resulted in two distinct ir-beta E peaks, with elution volumes corresponding to the mammalian beta-lipotropin and beta E, and three ir-ACTH peaks, the second one coeluting with mammalian ACTH. In the neural lobe the ir-ACTH/-beta E concentrations were similar to those in the hypothalamus. Resting plasma ir-ACTH (12.8 +/- 1.47 pmol/ml) but not ir-beta E (31.4 +/- 1.22 pmol/ml) levels were significantly increased following castration (to 41.4 +/- 1.11 pmol/ml). Serial blood sampling indicated pulsatile ir-beta E secretion (mean, coefficients of variation, and minimum-maximum range: 17.5, 62.78, and 2.9-49.7, respectively, for gander 1 and 23.3, 62.85, and 5.00-61.5, respectively, for gander 2).

Adrenocorticotropic Hormone↗
PubMed1998

Relationship between blood pressure variability and serum dehydroepiandrosterone sulfate levels.

Decreased diurnal blood pressure variability and low dehydroepiandrosterone sulfate (DHEAS) levels are important predictors of cardiovascular morbidity and mortality. The aim of the study was to determine the relationship between DHEAS levels and diurnal blood pressure variability in normotensive subjects and in patients with essential hypertension of both genders. An ambulatory blood pressure monitor (ABPM), Meditech O2 device and radioimmunoassay were used for ambulatory blood pressure monitoring and the determination of DHEAS levels, respectively. A close correlation (P < .001) was found between the diurnal indices and plasma DHEAS levels of the 387 subjects (86 normotensive and 301 hypertensive patients) participating in the study. Decreased plasma DHEAS levels were associated in both genders, and in both normotensive and hypertensive patients with significantly (P < .001) lower diurnal indices. There was a close correlation (P < .001) between the age-related decrease in plasma DHEAS levels and diurnal indices in both genders. Systolic and diastolic blood pressure variability changed parallel to plasma DHEAS levels in both genders, whether hypertension was present or not. Additional investigations are needed to find out whether reduced DHEAS levels play a role in decreased diurnal indices or whether both can be traced back to one and the same cause.

Adult↗
PubMed1998

Evaluation of Meditech ABPM-04 ambulatory blood pressure measuring device according to the British Hypertension Society protocol.

BACKGROUND: The use of ambulatory blood pressure measuring devices has become widespread in the diagnosis of hypertension. The accuracy of the device is fundamental for the diagnosis and treatment of the disease. OBJECTIVE: Internationally accepted validation of the newest ambulatory blood pressure measuring device, the ABPM-04 prototype, manufactured by Meditech Ltd. PATIENTS AND METHODS: Validation was carried out by assessing 94 outpatients, according to the British Hypertension Society protocol. RESULTS: The test device achieved grade B on the scale defined in the British Hypertension Society protocol, for both systolic and diastolic blood pressure. The mean and standard deviation of the difference between measurements of the test device and the mercury standard for both systolic and diastolic blood pressure were within the recommendations of the Association for the Advancement of Medical Instrumentation. CONCLUSION: The present study demonstrates that the Meditech ABPM-04 ambulatory blood pressure measuring device complies with the above mentioned requirements, and thus can be recommended for clinical use.

Blood Pressure↗
PubMed1998

Catecholaminergic control of intracellular free calcium and beta-endorphin secretion of rat pituitary intermediate lobe cells.

Individual melanotropes and intermediate lobes were tested to elucidate the role of alpha- and beta-adrenergic and D-2 dopamine receptors in the regulation of concentration of intracellular free calcium ([Ca2+]i) and release of beta-endorphin. Hormone secretion was studied in a superfusion system, while [Ca2+]i was measured microspectrofluorimetrically. Noradrenaline (1 microM) resulted in a slight decrease, then a marked increase in [Ca2+]i and secretion of beta-endorphin. The nonselective beta-adrenergic agonist isoproterenol (1 microM) increased [Ca2+]i and secretion of beta-endorphin; this effect was blocked by the beta-antagonist propranolol (10 microM). The alpha-adrenergic agonist phenylephrine (1 microM) increased [Ca2+]i and beta-endorphin secretion, but this effect was not blocked by terazosin or prazosin (alpha1-adrenergic antagonists, 1 microM). Administration of the alpha2-adrenergic agonist xylazine (1 microM) increased [Ca2+]i but did not affect secretion of the hormone. Biphasic effect of noradrenaline was tested in presence of adrenergic and dopaminergic antagonists. The noradrenaline-induced rise in [Ca2+]i and beta-endorphin secretion was decreased by propranolol, but this drug did not modify the inhibition. In the presence of 1 microM sulpiride (selective D-2 dopaminergic antagonist), the inhibitory phase of the curve was abolished, and the subsequent increase was reduced. This suggests that activation of dopamine D-2 receptors is involved not only in the inhibition, but also in the subsequent increase, which may originate from a rebound after the termination of the activation of these inhibitory receptors. Our data suggest the presence of several distinct types of catecholamine receptors in the rat intermediate lobe, and the dominant involvement of D-2 and beta-adrenergic receptors in the noradrenaline-induced regulation of melanotropes.

Adrenergic Agonists↗
PubMed1997

Effects of anterolateral and posterolateral cuts around the medial hypothalamus on the immunoreactive ACTH and beta-endorphin levels in selected brain regions of the rat.

To evaluate the relative weight of the ACTH-ergic and beta-endorphin-ergic pathway(s) leaving the medial hypothalamus (MH) in anterior or posterior directions immunoreactive ACTH and beta-endorphin (ir-ACTH and ir-betaE) were quantified in selected brain regions of the rat 7-8 days after placing anterolateral (ALC) or posterolateral (PLC) cut around the MH. Retrograde accumulation of both peptides was observed in the MH after ALC, but not after PLC. ALC resulted in dramatic decrease in ir-ACTH/ir-betaE concentrations in all extra-MH brain regions tested (extra-MH hypothalamus, septum, thalamus, hippocampus, amygdala, and medulla oblongata). In contrast, ir-ACTH and ir-betaE levels decreased only in the thalamus and in the medulla oblongata after PLC. The present data indicate (a) ACTH- and betaE-like substances synthesized in the arcuate region of the hypothalamus are axonally transported to extrahypothalamic brain regions by neuronal pathways leaving the MH primarily anterolateral, anterodorsal, or anteromedial direction (even the fibers of certain posteromedial or posterolateral projections leave the MH some anterior directions); (b) the posterior ACTH-/betaE-ergic projections seem to be of minor importance except for the thalamus and the medulla oblongata where it contributes to about one-third of the peptide content. Our biochemical study provide quantitative complementary data to the detailed immunohistochemical picture of the ACTH/betaE-ergic projections in the rat brain described by Khachaturian et al.

Adrenocorticotropic Hormone↗
PubMed1997

Domperidone stimulates prolactin secretion in rats with complete destruction of the mediobasal hypothalamus.

The main objective of this study was to further elucidate the functional relationship between endogenous dopamine and the prolactin (PRL)-releasing effect of the dopamine antagonists domperidone and haloperidol. We studied the effect of the above dopamine antagonists on the PRL secretion in control and mediobasal hypothalamus (MBH)-lesioned rats. Significant increase in basal plasma PRL levels was detected 7 days after complete surgical destruction of the MBH. Haloperidol injection (0.5 mg/kg, i.v.) was followed by an increased plasma PRL concentration in the sham-operated animals; however, in the MBH-lesioned rats where the basal PRL levels were high haloperidol failed to produce additional PRL release. In contrast to haloperidol, domperidone (0.1 mg/kg, i.v.) was able to further elevate the MBH-lesion induced high plasma PRL concentration. Moreover, the change in plasma PRL levels of the MBH-lesioned rats was parallel with that in the sham-lesioned animals after domperidone injections. When haloperidol was given prior to the domperidone injection it did not influence the PRL releasing effect of domperidone in MBH-lesioned animals. The PRL stimulatory effect of domperidone (0.3 mg/kg, i.v.) in MBH-lesioned rats was antagonized by dopamine (20 micrograms/kg, i.v.) and bromocryptine (20 micrograms/kg, i.v.). The above results suggest that the stimulatory effect of domperidone on the pituitary PRL secretion is mediated--at least in part--through the pituitary D2 dopamine receptors, but not by the displacement of endogenous dopamine originating from the MBH and reaching the pituitary via portal vessels.

Animals↗
PubMed1997

Age-dependent muscarinic stimulation of beta-endorphin secretion from rat neurointermediate lobe in vitro.

The effect of acetylcholine on the neurointermediate lobe beta-endorphin secretion was studied in the neonatal and in the adult rat in vitro. Acetylcholine stimulated beta-endorphin secretion from the 2-day- and 5-day-old neurointermediate lobe, the effect was dose dependent and more pronounced in the presence of the cholinesterase inhibitor eserine. The 10-day-, the 21-day-old and the adult rat neurointermediate lobes did not respond to acetylcholine, even in the presence of eserine. Basal beta-endorphin secretion was elevated by the D2 receptor antagonist sulpiride, but acetylcholine was without effect in the 10-day-old and in the adult neurointermediate lobe even after dopamine receptor blockade. The beta-endorphin stimulatory response to acetylcholine was diminished by the M1 muscarinic receptor antagonist pirenzepine and blocked by the M3 > M1 antagonist 4-diamino-phenyl-piperidine (4-DAMP). The selective M2 antagonist methoctramine and nicotine had no effect. These data indicate that the neurointermediate lobe beta-endorphin secretion is under special muscarinic cholinergic regulation for a relatively short time after birth. The disappearance of this stimulatory cholinergic effect in later life might be due to changes in the intracellular secretory machinery in the IL and/or to the uncoupling of the cholinergic receptors from the intracellular signal transduction system(s) responsible for the stimulated secretion in the rat melanotrope cells.

Acetylcholine↗
PubMed1996

Compression of the pituitary stalk elicits chronic increases in CSF vasopressin, oxytocin as well as in social investigation and aggressiveness.

The neurochemical and behavioural effects of a novel stereotaxic surgical method developed for interrupting the nerve fibres running through the rat pituitary stalk to the posterior pituitary gland was studied. The cerebrospinal fluid (CSF) vasopressin (AVP) and oxytocin (OT) content as well as changes in aggressiveness were measured in rats one week and one month after the surgical intervention. The main results are as follows: (1) the compression of the pituitary stalk elicits a chronic increase in water consumption, as well as in CSF vasopressin and oxytocin content; (2) the surgical intervention increased the frequency of clinch fighting after one week. The increase in aggressiveness accentuated after one month and, in addition, operated animals showed reduced scores of resting while exploratory and social behaviours increased; (3) there was a strong positive correlation between water consumption, vasopressin, and aggressiveness; (4) oxytocin changes showed a positive correlation with variation in social behaviour. The surgical intervention may serve as a model for lesions of the pituitary stalk and formation of ectopic neurohypophyses in humans.

Aggression↗
PubMed1995

Hormonal and metabolic responses during psychosocial stimulation in aggressive and nonaggressive rats.

The physiological effects of a psychosocial threat (the mere presence of a potentially antagonist individual in the home cage) were studied in aggressive and nonaggressive rats. Aggressive animals spent a significantly longer time with the investigation of the opponent compared with the nonaggressive group. An increase in plasma epinephrine and corticosterone was noticed both in aggressive and nonaggressive animals. Ir beta-endorphin increased significantly only in nonfighters. Glycemia was slightly larger in nonaggressives, while lactaemia increased in both groups. The possibility is discussed that differences in psychosocial stress response may be involved in the regulation of behavior in a real encounter.

Adrenocorticotropic Hormone↗