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Biomedical subjects

V F Puchkov

Publications and source records attributed to V F Puchkov.

At least 19 recordsLinked to original sources
PubMed2004

Characteristics of cellular proliferation in the developing human retina.

The expression of proliferation-associated proteins Ki67 and PCNA was studied in the retinal rudiments of human embryos at 5-8 weeks of development; studies also addressed the numbers of nucleoli in the nuclei of neuroepithelial cells (with consideration of their distances to the apical surface) and DNA-synthesizing cells after transient (20 min) in vitro incubation in serum-free medium containing BrdU. The retinal rudiment of embryos at five weeks of development had neuroepithelium of the typical structure. BrdU-positive nuclei and nuclei with small numbers of nucleoli were located in the basal part of the ventricular zone. However, this organization was disrupted during the initial period of formation of the inner nuclear layer (six weeks). At this time, DNA-synthesizing cells were found even at the apical surface. Retinal rudiments of embryos at 6-7 weeks of development contained an additional area of cell proliferation in the Chievitz layer and the inner nuclear layer. In eight-week embryos, dividing cells were located in the outer nuclear layer, which again acquired the organization typical of neuroepithelium.

Cell Division↗
PubMed2003

[Characteristics of the cell proliferation in the developing human retina].

The retinal primordia were studied in human embryos at developmental weeks 5-8 to examine the expression of proliferation-associated proteins (Ki67 and PCNA), the number of nucleoli in the nuclei of neuroepithelial cells (in respect to their distance to the apical surface) and the distribution of DNA-synthesizing cells after a short-term (20 min) incubation in vitro in serum-free medium containing BrdU. In 5-week embryos, retinal primordium contains the neuroepithelium with a typical structure. BrdU-positive nuclei and nuclei with small number of nucleoli were found in the basal portion of the ventricular zone. However, this organization was disturbed in the initial period of the formation of inner nuclear layer (week 6). At this stage DNA-synthesizing cells were seen even at the apical surface. In retinal primordia of embryos at weeks 6-7 there appeared an additional area of cell proliferation in the Chievitz layer and in the inner nuclear layer. In embryos at week 8 the dividing cells were concentrated in the outer nuclear layer, which has regained the organization, typical for a neuroepithelium.

Cell Division↗
PubMed2000

[Reactive invagination of the neuroepithelium in anlages of the human neocortex, tectum of the midbrain, and the retina at various stages of development].

Intensity of invagination of neuroepithelium of neocortex of human embryonal anlages of neocortex, tectum of the midbrain and retina was studied as a response to mechanic damage of ventricular zone induced in the course of preparation of the anlages to explanation. It was shown that no invagination formed in 24 hrs of the explantation. In neocortical anlage intensity of invagination was meximal in 6.5 wks embryo. In tectum invagination intensity of th explants lowered gradually from wk 5 to wk 7.

Cell Movement↗
PubMed1998

[The reaction of the rat thymus to xenotransplantation and immunosuppression].

To the complex action of human embryonal neocortex transplanted into the eye anterior chamber and cyclosporin A injected daily to prevent graft rejection rat thymus reacts by accidental involution, layer inversion and vascular disturbances (without hematoma formation). After 3 wks reparative period sets in and by the end of 5th wk thymus approximates to the control in all parameters.

Animals↗
PubMed1997

[The reactions of different sections of human embryonic neuroepithelium to damage to the ventricular surface during explantation].

Fragments of different regions of brain, spinal cord and retina obtained from 6 up to 7 wk human embryos were placed into media 199. On 24th hr of cultivation multiple invaginations developed in the explant ventricular surface as a response to its damage while preparing to explantation. Maturity extent of neural and glial elements was not essential to invagination intensity. Fragments of tectum and retina that are characterised by permanent shape of ventricular surface displayed minimal activity. These data suggest that the reaction considered reflects a property of neuroepithelial cells that constitutes an important factor in normal brain morphogenesis.

Brain↗
PubMed1997

[Mitotic activity and rosette formation in the neuroepithelium of the embryonic human neocortex in vitro].

Fragments of anterior cerebral vesicle wall were exposed in 6-8 weeks human embryos and cultured for up to 48 hrs in media 199. Two types of neuroepithelial cells dynamics were demonstrated: the first one is associated with invaginative movements of the layer (apical contractions and elongation of neuroepithelial cell processes are seen, the other one-with cell mitotic division (apical processes become shorter and wider and nuclei reach germinal zone). Prevalent cell dynamics type is determined by media composition. Type I predominates in serum-free media, while type II-in media containing embryonal serum. The lack of correlation between the extent of neuroepithelial layer bending and number of mitotically dividing cells in it indicates invagination process independence from cell divisions. Thus, neuroepithelial layer invagination is not stimulated by mitotic activity and does not stimulate it.

Cerebral Cortex↗
PubMed1996

[Rosette formation in explants of human embryonic neocortex (an electron-microscopic study)].

Multiple invaginations and closed cavities (rosettes) were developed in 199 fragments of wall of human anterior cerebral vesicle. Contraction of neuroepithelial cells apexes after the principle of the gathered tobacco pouch was involved into the process. This confirms the previous suggestion of the authors on the similarity between the mechanisms of rosettes forming and neurulation. The participation of radial glia cells and neuroblasts in the reorganization of the neocortex germ was also studied.

Cells, Cultured↗
PubMed1996

[Vascularization of the human embryonic neocortex in the rat anterior chamber under cyclosporine A immunosuppression].

Fragments of 9 weeks hyman embryo neocortex were grafted into the rat eye anterior chamber. To prevent rejection cyclosporin A was introduced to the animals. Vascular network forming in transplants was studied for 5 weeks 3 days endothelial buds from the iris vessels appeared in transplants. After 10 days capillaries with erythrocytes appeared in the graft on the border with iris. 3 weeks later vascular network achieved its maximal development, occupying almost the entire graft thickness. The vessels developed diverged from the norm: they had variceal widenings, and focal distribution with significant non-vascular gaps.

Animals↗
PubMed1995

[The toxic effect of serotonin in direct and mediated actions on rat embryos].

Embryotoxic effect of serotonin in direct (intra-amniotic administration) and indirect (subcutaneous administration) treatment was studied. In both cases serotonin causes embryo death and different abnormalities in development in small number of embryos. Mechanism of serotonin embryotoxic effect is under discussion.

Abnormalities, Drug-Induced↗
PubMed1990

[Effect of sodium diethyldithiocarbamate on embryogenesis in mice].

Sensitivity of mouse embryos (8-11 days old) to sodium diethyldithiocarbamate (SDDC), inhibitor of dopamine -beta-hydroxylase, has been investigated. SDDC produces certain anomalies in development of the CNS, facial skull, mandible , extremities and others. It is possible that the base of the mechanism, stimulating development of these anomalies, together with the other causes, can be some disturbances in catecholamine metabolism. This, in its turn, can result in disorders of cell interactions via neurotransmitters during active morphogenetic processes.

Abnormalities, Drug-Induced↗
PubMed1990

[Morphologic characteristics of intercellular junctions in early embryogenesis of mice].

Dynamics concerning certain intercellular junctions have been followed during the preimplantation period of development in mouse embryos. The morphological analysis of the preimplantational embryos has demonstrated, that at the initial stages of cleavage (2-4 blastomeres) the cells make contacts by means of nonspecific junctions. Specialized intercellular junctions appear at the stage of 8 blastomeres and are presented as dotted tight and gap junctions. When the embryo is developing from the stage of 8 up to the stage of 16 blastomeres, certain connective complexes appear, consisting of dotted or cord-like tight and gap junctions. At the late morula stage, the external blastomeres in the apical part have contacts with each other by means of cingular tight junctions. In this place a connective complex might emerge; it is displayed as a tight junction and one or two gap junctions. At the blastocyst stage desmosomes and adhision zones appear. Between trophectodermal cells a connective complex arises; it is presented in the slice as a tight cingular junction, desmosomes (as a rule two) and an adhision zone. Between cells of the internal cellular mass the intercellular junctions are presented as dotted tight and gap junctions. Cells of the polar trophoectoderm and cells of the internal cellular mass could have contacts by means of gap and dotted tight junctions.

Animals↗
PubMed1988

[Alcohol-drug interaction in rat embryogenesis: the effect of separate and combined action of sodium salicylate and ethanol].

A combined administration of sodium salicylate and ethanol to female rats in threshold embryotoxic doses on the 9th, 10th, 12th and 13th days of pregnancy results in a sharp increase of embryolethal and teratogenic effects. The embryotoxic effect of sodium salicylate and ethanol at their combined injection exceeds the summational embryotoxic effect at the separate action of the preparations. The spectrum of malformations after their combined effect does not differ from that induced with sodium salicylate.

Abnormalities, Drug-Induced↗
PubMed1987

[Sensitivity of the primordia of various organs to chemical substances].

In the experiments performed in chick embryos, using the chick embryo screening test (CEST)-1 and CEST-2 technique, 100 various classes of chemical substances have been tested for teratogenic activity. Estimation of three morphogenetic systems (caudal part of the body, facial skull and extremities) has demonstrated that some of the substances do not produce any damaging effect, other produce some lesions in selected germs, the third influence two or three germs simultaneously. Similar picture is also specific for the effect of the chemical substances to the rat intrauterine development. Owing to data obtained, we come to the conclusion that for screening of embryotoxicity of various xenobiotics under in vivo and in vitro experimental conditions one should not orient to one single germ.

Animals↗
PubMed1982

[Morphofunctional regularities of evolution of the neuro-electric apparatus in fishes].

Generalization of the literature data makes it possible to consider evolution of the fish neuro-electrical apparatus from the point of view of morphological (morphofunctional) regularities formulated by A. N. Severtsov (1937). Besides, an attempt is made to present the evolutional formation of the electrical apparatus as a regular process developing on the basis of a general property of protoplasm to produce bioelectricity.

Animals↗
PubMed1981

[Comparison of the effectiveness of various methods of testing drugs for embryotoxicity].

A comparative investigation on efficiency of four modern methods for testing embryotoxicity (intraamniotic administration, cultivation of postimplanted rat embryos in medium when certain teratogens were administered by various methods, test techniques on pregnant animals, testing, by CHEST--chick embryo toxicity screening test--method on chick embryos) was performed with a well known teratogen -- cyclophosphamide. A satisfactory correlation between the results was obtained, but a greater efficiency, less time for obtaining final results and greater sensitivity was noted for the new test methods in comparison to routine testing on pregnant animals. Advantages and disadvantages of every method applied were discussed.

Amnion↗
PubMed1981

[In vitro development of the postimplantation embryos of laboratory rodents in human blood serum].

Rat and mouse embryos at the stage of the first somites formation (1-5 pairs) cultivated in human blood serum demonstrated its embryolethal and teratogenic effect. The embryos taken at a later stage (11-18 pairs of somites) developed normally and could be compared with the development of the rat embryos in homologous blood serum. There was no difference in the development when the embryos were cultivated either in male or female blood serum. The stage of embryogenesis 11-18 pairs of somites is recommended for in vitro experimental revealing in the human serum of embryotoxic factors induced by certain external influences.

Animals↗
PubMed1981

[Embryotoxic effect of cyclophosphamide after being biotransformed in a culture of postimplantation rat embryos].

Biotransformation of cyclophosphamide to teratogenous products in the presence of the rat hepatic microsomal fractions and NADP.H2 was carried out in the medium for cultivation of postimplantational rat embryos. Nontoxic concentrations of all components participating in the reaction and threshold concentrations of cyclophosphamide were defined. The results obtained were compared with the data of the drug action on the embryos of the same age developing in the maternal body. The developmental anomalies appeared to be similar in both cases. The method for detecting the teratogenous products of cyclophosphamide bioactivation in the culture has been demonstrated to be highly sensitive as compared with the standard biological tests.

Abnormalities, Drug-Induced↗