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Biomedical subjects

A V Agafonov

Publications and source records attributed to A V Agafonov.

At least 19 recordsLinked to original sources
PubMed2001

Differentiation in the Elymus dahuricus complex (Poaceae): evidence from grain proteins, DNA, and crossability.

The status of the taxa Elymus dahuricus Turcz. ex Griseb., E. excelsus Turcz. ex Griseb., E. woroschilowii Probat. and E. tangutorum (Nevski) Hand.-Mazz., all of which are sometimes treated as members of E. dahuricus s.l. or as constituting the E. dahuricus complex, has been investigated using morphological, biochemical (SDS-PAGE of endosperm proteins) and molecular (DNA-AFLP) variation characteristics. Populations include accessions from Siberia, Far East (Russia), Tien-Shan (Kirghizstan), and Tibet and Sichuan Provinces (China). Variation in the morphological characteristics and endosperm proteins patterns have been found in all populations of the complex. DNA variation was very low within populations but was different among populations; this was attributed to genetic drift. Seed fertility of artificial hybrids and F2-F3 progenies in 38 combinations was analyzed. All biotypes studied form a common recombination genepool (RGP). The reproductive compatibility of hybrid combinations decreases with increased geographical separation of the parents. Differences in protein patterns and in genetic variation drawn from DNA-AFLPs and phenotypical segregation in F2 on series of diagnostic characters does not support existing taxonomic treatments of the E. dahuricus complex in Southern Russia, and Central-Asian area. The E. dahuricus complex seems to be a polymorphic species having a wide geographical range and wide genetic variation. The different species need probably be relegated to infraspecific rank. We have refrained from making the necessary combinations pending examination of additional specimens, including specimens of taxa not included in this study and the type specimens of all taxa involved.

Analysis of Variance↗
PubMed1996

Light-induced reversible local fusions of thylakoid membranes in the presence of dibucaine or tetracaine.

The dynamics of structural changes in pea chloroplasts in the presence of 25-50 microM dibucaine or tetracaine has been examined using electron microscopy. The light-induced uptake of anesthetic cations by thylakoids is attended by the appearance of local fusions of stroma-exposed thylakoid membranes. The first membrane protrusions and interthylakoid contacts are observed after 4 s illumination and they become numerous by 10 s. As a result, a network of anastomoses is formed which is maintained during at least 10 min. These effects are reversible in the dark and can be reproduced several times. The formation of membrane fusions is inhibited by the addition of protonophore. It is supposed that the energy-dependent uptake of protonated anesthetics by thylakoids leads to an increase in positive surface charge and thus a lateral pressure on the inner side of the thylakoid membrane. The appearance of membrane protrusions (crinkles) having the positive curvature of their inner surface may be considered as a way of compensating for lateral pressure. Presumably, anastomoses result from the fusion of crinkles to adjacent thylakoids.

Anesthetics, Local↗
PubMed1992

[A system for the clinico-immunological prognosis of infectious-inflammatory complications in planned surgery].

Postoperative infectious complications in planned surgery are a pressing problem. The preoperative condition of the patient and his immune system play an important role in their development. Fifty patients of the "risk" group were selected from the standpoint of classification of the etiological factors of secondary immunodeficiency states. Fifteen patients who had no symptoms classified as SIDS risk factors formed the control group. The immune status was examined before and on the third day after the operation in all patients of the main and control groups. Various infectious complications developed after the operation in 23 patients of the risk group. No such complications occurred in the control group. The preoperative immune status of the risk group patients differed significantly from that of the controls in 13 of 19 parameters. The patients of the main and control groups formed the instructing selection. An expert system of preoperative clinico-immunological prognostication of postoperative infectious-inflammatory complications was created on oasis of the methods of the theory of image recognition and instructing selection. The system was tested in a direct clinical experiment on 66 patients. The prognoses were correct in 89% of cases. It was thus proved that symptoms classified as SIDS risk factors influence the initial immunity status and the course of the postoperative period in planned surgery. An accurate, sensitive, and specific method for prognosticating postoperative infectious complications is suggested.

Algorithms↗
PubMed1987

[Stenocardia].

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Adult↗
PubMed1979

[Sensitivity of different strains of the causative agent of plague to disinfectants].

Various strains of the plague microbe was found to have statistically significant differences in their sensitivity to phenol, formaldehyde and chloramine. These differences did not correlate with the origin, virulence and nutritional requirements of the plague strains. The sensitivity of the plague microbe to formaldehyde and phenol was found to be related to the permeability of its cell wall.

Animals↗
PubMedDate not supplied

[Analysis of the causes of potential wear and breakdown of elements of artificial heart valves of the disk type].

The reliability analysis of the artificial cardiac valve and experiments made it possible to establish that the ACV reliability is ensured by the physical and mechanical properties of the material, technology observance and thorough control over each operation during the manufacturing process. The accelerated testing of the new MX disk valve made in the USSR showed a satisfactory degree of the disk wear and the absence of breaks-down after 400 million working cycles which is equivalent to ten-years' work in a human body.

Heart Valve Prosthesis↗
PubMedDate not supplied

[Evaluation of the force loads on the elements of artificial heart valves from the results of processing echocardiograms].

Approaches to further improving the valve prosthesis construction greatly depend on the knowledge of the physical load affecting the elements of artificial cardiac valves that operate in the human organism. An analysis of echocardiograms is given. They were recorded in the patients with implanted artificial ball heart valves, type MK4-2.25. The design values for the force of the ball impact against the valve shell are presented. The echocardiogram analysis revealed a phenomenon of the fibrotic ring deformation under the ball action on the valve shell and the degree of this deformation has been determined.

Biomechanical Phenomena↗
PubMedDate not supplied

[Functional characteristics of flexible supporting structures for heart valve bioprosthesis].

Hydraulic characteristics of heart valve bioprostheses mounted on supporting structures of various rigidity have been studied under physiologic conditions. An actual mobility of the supporting structures made of different polymers is determined. Static and dynamic components of the support displacements have been shown to develop as the bioprosthesis is under the load, the dynamic component being strongly dependent upon the rigidity of fastening the bioprosthesis on the axis. It is noted that considerable improvements in hydraulic characteristics of bioprostheses are achieved through the use of flexible supporting structures.

Biomechanical Phenomena↗