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Biomedical subjects

S Todorov

Publications and source records attributed to S Todorov.

84 records · Page 5Linked to original sources
PubMed1973

[The phasic radiosensitivity of human lymphocytes to the effects of protons].

The authors presented data on cytogenetic analysis of lymphocytes from human peripheral blood, irradiated at the stage G0 and G2 of the cellular cycle. There was an increase of chromosomal aberrations with an increase of the dose. Furthermore the irradiation at stage G0 caused the formation of aberrations of chromosomal type, but irradiation at stage G2-aberrations of chromatid type. The increase of one-blow aberrations were of linear character at both stages.

Cells, Cultured↗
PubMedDate not supplied

[polyposis of the uterine cervix].

At the university Hospital Department of Gynecology and Obstetrics in Novi Sad from 1973 to 1976, the ablation of polyps and fractional curretage were performed in 626 women. Polyps were detected in 164 women of the generative age, in 387 women in perimenopause, and in 75 women in postmenopause. Only in 10 women (1.52%) was carcinoma verified: a carcinoma of the uterine body in 6 cases, a planocellular carcinoma of the uterine cervix in one case, and a malignant alteration of the polyp without malignity in the endometrium in 3 cases. Metaplastic changes were observed in 124 polyps. The author emphasises the need for the ablation of polyps and a simultaneous fractional curretage, especially in peri and postmenopause, in order to detect malignant changes as early as possible.

Dilatation and Curettage↗
PubMedDate not supplied

Role of histamine and histaminergic agents on noradrenaline uptake in smooth muscle preparations.

It has been shown that adrenergic neurotransmission in different tissues can be modified by histamine (HIST) but the mechanisms of this action have still not been fully clarified. This study aimed to demonstrate the possible involvement of H-receptor subtypes in the realization of histamine inhibitory effects on smooth muscle tissues. HIST, 2-(2-aminoethyl)thiazole (AET) and dimaprit (DMP) exerted a similar inhibition of noradrenaline (NA)-uptake1 in rat vas deferens and rabbit ear artery. After H1-blockade with mepyramine (MEP), HIST and DMP did not change the uptake1 in rat vas deferens and decreased NA neuronal accumulation in rabbit ear artery. The H2-blockade with ranitidine (RAN) did not affect HIST- and AET-induced inhibition of NA-uptake1 in rat vas deferens and completely abolished it in rabbit ear artery. These data suggest that different H-receptor subtypes might be involved in HIST inhibitory action on NA neuronal uptake in both tissues. It appears, however, that the inhibition of NA uptake1 plays only a minor role in the effects of HIST on smooth muscle contractions.

Animals↗
PubMedDate not supplied

Involvement of Ca2+ and alpha 1-adrenoceptors in endothelin-1 effects on the tone and electrically evoked contractions of rabbit ear central artery.

Endothelin-1 (ET-1) is a neuropeptide strongly involved in the functions of the cardiovascular system. The aim of the present study was to reveal the role of alpha1-adrenoceptors and of Ca2+ in the effects of ET-1 on blood vessels. Preparations isolated from the proximal part of ear central arteries (REA) of male Chinchilla rabbits were used. A 30-40 mm long segment, cannulated at both ends, was fixed in an organ bath with Krebs-Henseleit solutions aerated with 95% O2 and 5% CO2. The preparations were perfused at a rate of 3.0 ml/min maintaining the arterial pressure in the range of 40-60 HPa and were allowed a 120-min adaptation at 37.5 degree C. Contractions were induced by low-frequency electrical stimulation (ES) and the effects of ET-1 (applied intralumenally or extralumenally) on the arterial tone and on the Es-evoked contractions were studied. Extralumenal ET-1 (1 x 10(-12)M-1 x 10(-9)M) did not change the tone and ES evoked contractions of REA. In concentrations of 1 x 10(-8)M-1 x 10(-7)M ET-1 slightly increased arterial tone and moderately potentiated ES contractions. ET-1, in concentrations higher than 1 x 10(-7)M, sharply, strongly and long-lastingly increased the smooth muscle tone and slightly enhanced the ES contractions. A 100 microM bolus injection with ET-1 (1 x 10(-9)M-1 x 10(-8)M) resulted in potentiation of the ES contractions and the arterial tone was not markedly affected. 100 microM of 1 x 10(-7)M ET-1 increased more than 2-fold the tone of the segments and moderately reduced the ES-evoked contractions. A 30-min perfusion with ET-1 (1 x 10(-12)M-1 x 10(-9)M) strongly increased the arterial tone and completely abolished the ES contractions. Perfusion with 1 x 10(-8)M ET-1 resulted in a 3-fold increase of the tone of the isolated segments. A 30-min perfusion with 1 x 10(-6)M prazosin (PRZ) did not affect the arterial tone and prevented the ES-evoked contractions. PRZ markedly reduced the contractile effects of 1 x 10(-12)M-1 x 10(-9)M ET-1 and the effect of 1 x 10(-8)M ET-1 on REA tone was even enhanced by PRZ. Under the same conditions 1 x 10(-6)M flunarizine (FLU) inhibited the ES-induced contractions of the isolated preparations and decreased their tone. FLU reduced the contractile effects of ET-1 (1 x 10(-12)M-1 x 10(-8)M). Applied extralumentally 1 x 10(-6)M FLU also decreased EG-1 effects on REA. The results obtained strongly support the assumption that alpha1-receptors and Ca2+ are involved in ET-1 contractile effects on blood vessels smooth muscles.

Adrenergic alpha-Antagonists↗
PubMedDate not supplied

Interactions between histaminergic and cholinergic pathways of gastric motility regulation.

Smooth muscle preparations, isolated in a circular direction from guinea pig gastric fundus, were used to study the effects of H1 and H2 antagonists on acetylcholine (ACH)- and histamine (HA)-induced contractions as well as the effects of HA antagonists on spontaneous contractile activity. HA (1 x 10(-9) M to 1 x 10(-5) M) concentration-dependently enhanced the tone of the strips with ED50 = 3.5 x 10(-7) M. Applied 5 min before HA, the H1 antagonists (mepyramine, diphenhydramine, dimethpyrindene) and the H2 blockers (ranitidine, cimetidine, roxatidine) reduced HA-induced contractions. HA in concentrations of 1 x 10(-8) M to 1 x 10(-7) potentiated, and in higher concentrations (1 x 10(-6) M to 1 x 10(-5) M) inhibited, smooth muscle contractions evoked by low frequency electrical field stimulation (EFS). The H1 blockers (1 x 10(-6) M to 1 x 10(-4) M) concentration-dependently enhanced smooth muscle tone, the maximum contractions being about 50% smaller than the contractile responses to 1 x 10(-5) M ACH and 5 x 10(-5) M HA. Tetrodotoxin, atropine and indomethacin shifted to the right the concentration-response curve for mepyramine, reducing its maximum by 25, 58 and 62%, respectively. The H2 blocker ranitidine also suppressed (by 42%) mepyramine-evoked increase in the fundic strips tone. The H1 antagonists reduced ACH-induced contractions of the smooth muscle strips and did not affect the contractions in response to EFS. The H2 blockers had no effect on tone and ACH-evoked contractions of the smooth muscle strips but concentration-dependently enhanced both the contractions and [3H]-ACH release in response to EFS. The results demonstrate the presence of both H1 and H2 postsynaptic receptors which are involved in the direct myogenic action of HA on guinea pig gastric fundus smooth muscles. It also appears that HA might concentration-dependently modulate the cholinergic neurotransmission in gastric fundus. It could be suggested that H1 blockers have a direct myogenic effect on guinea pig gastric fundus smooth muscle and might also interact postsynaptically with muscarinic receptors in this tissue.

Acetylcholine↗