Biomedical subjects

V Pesić

Publications and source records attributed to V Pesić.

At least 19 recordsLinked to original sources

PubMed2006

Characterization of thymocyte phenotypic alterations induced by long-lasting beta-adrenoceptor blockade in vivo and its effects on thymocyte proliferation and apoptosis.

Adult male Wistar rats were subjected to propranolol (P, 0.40 mg/100 g/day) or saline (S) administration (controls) over 14 days. The expression of major differentiation molecules on thymocytes and Thy-1 (CD90) molecules, which are shown to adjust thymocyte sensitivity to TCRalphabeta signaling, was studied. In addition, the sensitivity of thymocytes to induction of apoptosis and concanavalin A (Con A) signaling was estimated. The thymocytes from P-treated (PT) rats exhibited an increased sensitivity to induction of apoptosis, as well as to Con A stimulation. Furthermore, P treatment produced changes in the distribution of thymocyte subsets suggesting that more cells passed positive selection and further differentiated into mature CD4+ or CD8+ single positive (SP) TCRalphabeta(high) cells. These changes may, at least partly, be related to the markedly increased density of Thy-1 surface expression on TCRalphabeta(low) thymocytes from these rats. The increased frequency of cells expressing the CD4+25+ phenotype, which has been shown to be characteristic for regulatory cells in the thymus, may also indicate alterations in thymocyte selection following P treatment. Inasmuch as positive and negative selections play an important role in continuously reshaping the T-cell repertoire and maintaining tolerance, the hereby presented study suggests that pharmacological manipulations with beta-AR signaling, or chemically evoked alterations in catecholamine release, may interfere with the regulation of thymocyte selection, and consequently with the immune response.

Adrenergic beta-Antagonists↗

PubMed2006

Morphometrical characteristics of age-associated changes in the thymus of old male Wistar rats.

In order to provide a morphometrical description of the changes in the aged rat thymus and to relate them to apoptotic and proliferative activity of thymocytes, the thymuses from 3- and 18-month-old male Wistar rats and the percentages of bromodeoxyuridine-incorporating and apoptotic cells in cultures of thymocytes were assessed by stereological analysis and flow cytometry, respectively. In old rats the volume of lymphoepithelial thymic tissue is markedly reduced, reflecting a sharp decrease in the total number of thymocytes. A reduction in the proliferative capacity of thymocytes and increase in their susceptibility to apoptosis are, most likely, primarily responsible for a 7-fold reduction in thymic cellularity in old animals. Furthermore, only the volume of cortical compartment was affected by aging, while that of medulla, despite of reduced cellularity, was not significantly altered. The loss of functional tissue in aged thymus is compensated by a substantial increase in the volume of inter-lobular connective and adipose tissue, so the thymic weight remained unaltered in old rats. These results suggest that thymus of aged Wistar rats exhibits morphological characteristics similar to those found in aged human thymus and thus may serve as an animal model for further investigations of thymus-related changes in immunological aging.

Aging↗

PubMed2005

Effects of extremely low-frequency magnetic field in the brain of rats.

An extremely low-frequency magnetic field (50 Hz, 0.5 mT) was used to investigate its possible effect on the brain of adult male Wistar rats following a 7-day exposure. The control rats were sham-exposed. Superoxide dismutase activities and production of superoxide radicals, lipid peroxidation, and nitric oxide were examined in the frontal cortex, striatum, basal forebrain, hippocampus, brainstem, and cerebellum. Significantly increased superoxide radical contents were registered in all the structures examined. Production of nitric oxide, which can oppose superoxide radical activities, was significantly increased in some structures: the frontal cortex, basal forebrain, hippocampus, and brainstem. Augmentation of lipid peroxydation was also observed, with significance only in the basal forebrain and frontal cortex, in spite of the significantly increased superoxide dismutase activities and nitric oxide production in the basal forebrain, and increased production of nitric oxide in the frontal cortex. The results obtained indicate that a 7-day exposure to extremely low-frequency magnetic field can be harmful to the brain, especially to the basal forebrain and frontal cortex due to development of lipid peroxidation. Also, high production of superoxide anion in all regions may compromise nitric oxide signaling processes, due to nitric oxide consumption in the reaction with the superoxide radical.

Animals↗

PubMed2004

Repeated exposure to low-level extremely low frequency-modulated microwaves affects baseline and scopolamine-modified electroencephalograms in freely moving rats.

PURPOSE: To compare in the electroencephalogram of rats the effects of scopolamine (an acetylcholine receptor antagonist) alone and after repeated exposure to low-level microwaves modulated at extremely low frequency. MATERIALS AND METHODS: Averaged frequency spectra (0.5-30 Hz) of the electroencephalogram were studied in freely moving rats with carbon electrodes implanted into the somatosensory cortex. The rats were repeatedly (3 days, 30 min day(-1)) exposed to low-intensity (approximately = 0.3 mW cm(-2)) microwaves (915 MHz, 20-ms pulse duration), amplitude modulated (square-wave) at extremely low frequency (4 Hz). RESULTS: The exposure to extremely low frequency microwaves alone significantly enhanced the fast electroencephalographic rhythms (18-30 Hz). This effect was observed neither in subsequent sham-exposure experiment nor in radiation-naïve animals. In the microwave-exposed rats, scopolamine (0.1 mg kg(-1), subcutaneously) did not cause a slowing in the electroencephalogram that was shown in non-exposed rats. A similarity between the scopolamine-induced electroencephalogram effect in the microwave-exposed rats and that of physostigmine (enhancing the acetylcholine level in the brain) in radiation-naïve animals was noted. This paradoxical phenomenon stimulates new experimentation for understanding its mechanism(s). CONCLUSIONS: The data obtained provide additional evidence that repeated low-level exposure to extremely low frequency microwaves can modify an activity of cholinergic system in the brain.

Animals↗

PubMed2000

beta-Adrenergic receptor manipulation and acid phosphatase and zinc levels in the ventral prostate of the adult rat.

The influence of 15-day treatments with the beta-adrenergic receptor agonist isoproterenol (120 micrograms/kg/d) or the antagonist propranolol (1.00 mg/kg/d) on acid phosphatase and zinc levels in the ventral prostate was examined in intact rats, rats simultaneously injected with dexamethasone (0.25 mg/kg/d) and animals chemically castrated with a single dose of ethane dimethanesulphonate (75 mg/kg). Isoproterenol-treatment significantly increased acid phosphatase concentration in the ventral prostate of intact rats, whereas propranolol prevented a glandular zinc loss induced by dexamethasone administration. These results demonstrate that the levels of both biochemical parameters in the prostate can be altered by beta-adrenergic receptor manipulation. The responsiveness of the two secretory processes is different and depends on the functional status of the ventral prostate.

Acid Phosphatase↗

PubMed1991

[The relations of the mandibular canal with the outer surfaces of the body of the mandible and the risks which arise from its injury].

The investigations of relations and position of the mandibular canal (CM) were carried out on 80 mandibles (33 dentulous, 27 partly edentulous and 20 completely edentulous). The studies of relations of CM to the sides of mandibular body were accomplished by morphometric analysis of CM on consecutive transversal sections of mandibular body (54 preparations). The relation of the CM to be buccal or to the lingual side is expressed as the distance from the surface of the correspondent side of the mandibular body, which is shown in Table 1. According to these data, the position of the canal is at first proximate to the lingual side, and from the first molar tooth (M1) it approaches the buccal surface of the mandibular body. The position of the entire CM was determined by analysis of mandibular preparations (26) after removing the buccal osseous lamina. These investigations revealed that the position of the CM is predominantly buccal. Reconstruction of relations of the CM to the sides of mandibular body, according to the data obtained from transversal sections, and the real position of the CM are presented in Scheme I. The difference in direction lines of relations and of predominant position of the CM is a consequence of morphological characteristics of mandibular body.

Adult↗

PubMed1990

Dependence of the renal excretion of theophylline on its plasma concentrations and urine flow rate in asthmatic children.

The dependence of the renal excretion of theophylline on its plasma concentration and urine flow rate has been investigated in asthmatic children of either sex. One group (age 12.25 +/- 0.80, mean +/- s.d. n = 8) was given aminophylline intravenously (i.v.), while another (age 10.00 +/- 3.64 n = 14) was given a sustained release preparation of theophylline orally (single dose and repeated doses). Unchanged drug (11.6% +/- 1.75) was excreted in the urine corresponding to a renal clearance of 10.6 +/- 1.6 mL h-1kg-1. Time dependence of the renal clearance of theophylline was found only after i.v. administration. Dependence of the renal clearance on urine flow rate was found both after i.v. administration and at steady state, but not after a single oral dose of theophylline. After oral administration, renal clearance of theophylline was higher at steady state than after a single dose (0.58 +/- 0.06 L h-1 kg-1 vs 0.23 +/- 0.03 L h-1 kg-1), while urine flow rate was lower (1.1 +/- 0.5 mL min-1 vs 1.8 +/- 0.9 mL min-1). High correlation of theophylline plasma concentration and theophylline excretion rate was obtained in 10 of 14 patients after administration of a single oral dose of the preparation (r = 0.8567 to 0.9830). There was no dose dependence of the renal clearance of the drug either after a single dose, or at steady state.

Administration, Oral↗

PubMed1989

[Atherosclerotic changes of the inferior dental artery correlated with those of the carotid bifurcation and the abdominal artery].

50 corpses from adults aged 20 to 75 have been used in order to study the atherosclerotic lesions occurring in typical regions (bifurcation of the common carotid artery and the abdominal aorta) and their relationship to atherosclerotic changes in the inferior alveolar artery. Histological analysis revealed that atherosclerotic alterations of the inferior alveolar artery may appear sometimes earlier than it would be expected on the ground of age. Intima cell proliferation and thickening of elastic elements in the middle layer of the arterial wall, the first signs of atherosclerosis, were found already at the beginning of the third decade of life when the signs of this process in the typical regions were not yet evident. Atherosclerosis affects essentially the functional capacity of the inferior alveolar artery. The development of atherosclerosis in the wall of this artery favours an hypovascularization of the mandible, which must be of certain importance in every operative procedure in oral surgery, especially in those inducing a severe and long traumatism in bone and soft tissues, such as dental implantations.

Adult↗

PubMed1988