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O V Boĭko

Publications and source records attributed to O V Boĭko.

At least 19 recordsLinked to original sources
PubMed2003

[Functional and structural characteristics of the nephron segments].

The review presents a modern view on the functional--morphological peculiarities of 12 segments of the nephron canaliculi possessing some functional, biochemical and histologic distinctions that should be taken into account to study physiology, biochemistry, morphology and pathophysiology of the kidney.

Animals↗
PubMed2000

[Pharmacokinetic analysis of alpha- and beta-adrenoreceptors in the chick embryo amnion].

Following a stimulation with acetylcholine, the beta-adrenergic agonists adrenaline (A), noradrenaline (NA), isoproterenol (Iso) and salbutamol (Sal) induced a concentration-dependent decrease in the tone and (or) rate of amnion contraction with EC50 ISO < NA << A < Sal. Metaprolol, a specific beta 1-antagonist, induced a rightward shift in the dose-response curves of Iso, NA and A, whereas beta-antagonist butoxamine was ineffective. pA2 values for beta-antagonists were propranolol 8.3, metoprolol 7.0, butoxamine 5.6. EC50 values of alpha-adrenergic agonists form a sequence: clonidine < NA << methoxamine < phenylephrine. Specific alpha-antagonists yohimbine and idazoxan were found to antagonise competitively the effects of NA. The data obtained characterize the adrenergic receptors mediating stimulation of amniotic contractile activity as alpha 2-adrenergic receptors. Inhibition of contractile receptors in amnion is mainly mediated by beta 1-adrenergic receptor activation.

Adrenergic Agonists↗
PubMed1998

[Quantitative analysis of ligand-receptor interactions in physiological experiments].

In isolated smooth muscles of the sea cucumber, the rat intestine, vas deferens and portal vein, and in chick embryonic amnion, contractile responses of smooth muscles to transmitters and their agonists were described with two equations: p = (Pm.A(n))/(EC50n + A(n)) [7] or p = [(Pm1.An1)/(EC50(1)n1 + An1)] + [(Pm2.An2)/(EC50(2)n2 + An2)] [8]. The findings reveal a possibility of ligand-receptor interaction according to several models: a single receptor pool with n = 1 or n not equal to 1; two receptor pools in the same effector system with n1 = n2 or n1 not equal to n2.

Acetylcholine↗
PubMed1988

[Seasonal variability in the cholinergic reaction of the frog heart].

Seasonal changes in sensitivity to acetylcholine were studied on the isolated frog ventricle. The highest sensitivity was observed in autumn and winter (November-January). In spring, from the period of reproduction, the sensitivity to acetylcholine drops to-threefold and remains at a low level until September. Seasonal changes were more obvious in females. The observed seasonal changes are discussed with reference to ecology, state of reproductive system, etc.

Acetylcholine↗
PubMed1988

[Seasonal characteristics of the emergence from inhibition by and desensitization to acetylcholine of the frog heart muscle].

Seasonal changes in the sensitivity to acetylcholine (I/KACh), the time of recovery of half-amplitude (T50), as well as the ACh desensitization were studied in ventricles of the frog Rana temporaria. Cardiac arrest could be induced with 10(-7) to 10(-6) M ACh in winter whereas in spring small rhythmic contractions were observed even at 10(-3) M ACh. A correlation between the heart sensitivity to ACh and the time of the heart beat resuming was found: a decrease in the I/KACh corresponded to the 2-3-fold decrease in the T50 in spring and summer. After repeated ACh application the heart sensitivity decreased by 1.5-2.0-fold, i.e. a desensitization occurred. The data obtained are discussed in respect to the phenomenon of escape and involvement of putative modulators of the cholinergic responses: polyphosphates, lysolecithin, hormones.

Acetylcholine↗
PubMedDate not supplied

[Effects of toxic substances on opportunistic microorganisms].

Anti-immunoglobulin activity of immunoglobulins, rarely receiving attention in literature, occupies a special place among the special bacterial substances released by bacteria exocellularly. We studied the effects of some pollutants (phenol, diethanolamine, nitric and hydrochloric acids) on this pathogenicity factor. Phenol and hydrochloric acid added to tap water caused statistically significant changes in anti-immunoglobulin activity of Klebsiella strains.

Disinfectants↗
PubMedDate not supplied

[Kinetic of beta1-adrenergic reaction of chicken embryo amnion].

Dose-dependent curves of the inhibitory beta 1-adrenergic reaction of the chick embryo amnion were analyzed on the basis of different mathematical models. Selection of the optimal model, closest to the experimental data, allows us to obtain the reaction parameters with the smallest statistical error. Two main characteristics of the physiological reaction, EC50 and Pm, sufficed for the description of the action of agonists nonselective for beta 1-adrenoreceptors: adrenaline (EC50 0.19 +/- 0.02 microM, Pm 101.3 +/- 1.9%) and salbutamol (EC50 0.58 +/- 0.01 microM, Pm 42.7 +/- 0.3%). The Hill coefficient n in these experiments was close to 1 (1.06 +/- 0.14; 0.96 +/- 0.02). It was necessary to introduce fractional values 1 < n < 2 to describe the effects of noradrenaline and isopropyl noradrenaline.

Adrenergic beta-Agonists↗
PubMedDate not supplied

[Ejaculate microflora sensitivity to lactoferrin in chronic prostatitis].

To determine an antimicrobial action of lactoferrin on bacterial flora of ejaculate in chronic prostatitis, we examined 124 patients with various diseases of male reproductive system at the age between 17 and 56. A total of 280 strains were used as test microorganisms (MO). Sensitivity of the latter to lactoferrin was studied with a human lactoferrin apoform. MO isolated from patients with marked dysbiosis were resistant to lactoferrin (94%). MO, not leading in cenosis, were more sensitive to lactoferrin than MO of the main colonies grown after seeding. Reproductive dysfunction was accompanied by higher occurrence of strains resistant to lactoferrin. The least sensitivity to lactoferrin was registered in asthenozoospermia. Lactoferrin resistance of MO may raise MO pathogenicity. When lactoferrin-resistant strains predominate in microbiocenosis, it is an unfavourable prognostic sign in relation to development of complications, primarily subfertility.

Adolescent↗
PubMedDate not supplied

[Catecholamines and DOPA in the amniotic fluid and amnion of the chick embryo].

Identification and quantitative fluorimetric assay have been made on the content of DOPA, dopamine, noradrenaline and adrenaline in the amniotic fluid and amnion of the developing chick embryos. Significant increase in the content of DOPA, noradrenaline and adrenaline in the amniotic fluid was observed between the 6th and the 13th days of incubation; dopamine content sharply decreases at the 13th day. The content on amines in the amnion tissue remained essentially constant throughout the investigated period. The role of catecholamine in amniotic fluid in regulation of contractile activity of amniotic membrane in the developing chick embryo is discussed.

Amnion↗
PubMedDate not supplied

[The cholinergic reaction of the amnion in the chick embryo].

Studies have been made of the spontaneous contractions of the amnion and acetylcholine sensitivity of amniotic membrane in 8--14-day chick embryos. In 12--14-day embryos, the spontaneous rhythmic contractions were rather rare as compared to those in 8--9-day ones, their frequency being also lower. On the basis of kinetic analysis, it was concluded that both the dissociation constant (K) and the value of Pmax do not exhibit significant changes for tonotropic reaction from the 8th to the 14th day and for chronotropic reaction--from the 8th to the 10th day of incubation. After the 10th day of incubation, dose-effect chronotropic reaction not expressed. The spontaneous activity of the amnion and acetylcholine sensitivity of the amniotic membrane depend on the temperature being maximal at 38 degrees C. Possible regulatory mechanisms of contractile activity in chick amnion are discussed.

Amnion↗