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Biomedical subjects

G N Chaldakov

Publications and source records attributed to G N Chaldakov.

At least 37 records · Page 2Linked to original sources
PubMed1990

Ciliated fibroblasts and smooth muscle cells in the rat uterus.

Ciliation in endometrial fibroblasts and myometrial muscle cells of the rat was examined by transmission electron microscopy. Quantification of the number of ciliated cells during the estrus cycle did not show any firm relationship between ciliation and ovarian hormonal activity. In the case of most cilia, there is a spatial relationship between their basal centrioles and the Golgi complex, so that a Golgi-cilium complex is created. A possible role of ciliation in uterine fibroblasts and smooth muscle cells is discussed.

Animals↗
PubMed1990

Internalized gap junctions in ciliary epithelium of rabbit and rat. A transmission electron-microscopic study.

Transmission electron microscopy was used to examine internalized gap junctions (IGJ) in rabbit and rat ciliary epithelial cells. A prominent feature of all the specimens studied was the presence of different images of IGJ membrane that entrapped a portion of an adjoining cell. We documented and analyzed more than 500 gap junction (GJ) vacuoles and invaginations, the latter comprising less than 20% of all the structures examined. With ten exceptions found in non-pigmented cells, all the IGJ were unidirectionally internalized within the cytoplasm of pigmented epithelial cells. Morphological signs of autophagic degradation of GJ vacuoles were observed. An essential finding was that once a GJ membrane started to invaginate, a "lucidation" of a part of the protruding cytoplasm occurred; no planar GJ membranes exhibited such an alteration. The present finding suggest that IGJ derived from the epithelium of ciliary processes arise through an invagination-endocytosis mechanism and are degraded autophagically. This phenomenon may be relevant to aqueous humor production.

Animals↗
PubMed1990

Inhibition of receptor-mediated cellular entry of viruses including HIV: a perspective on further researches on chemotherapy in viral diseases including AIDS.

Receptor-mediated endocytosis is a well recognized process by which many cells internalize and intracellularly process important biological molecules including viruses. The present hypothesis, addressing receptor-mediated cellular entry of viruses including HIV, describes a perspective of further basic studies seen through the current knowledge about pharmacological control of various steps of receptor-mediated endocytosis of different ligands and viruses as well. It proposes a list of more than 20 chemicals, targeted at inhibition of viral internalization and viral release into the cytoplasm, via their action(s) on transglutaminase, calmodulin, protein kinase C, and intraendosomal pH. It is cautiously suggested that a proper study of these chemicals may reveal some therapeutic values of their own in some viral diseases including AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Morphological evidence for calcium storage in the chromatoid body of rat spermatids.

Morphological evidence for probable Ca2+ storage in the vesicular elements of the rat spermatid chromatoid body is documented using the K-pyroantimonate method, combined with EDTA chelation. Some vesicles are related to the microtubules associated with the chromatoid body. A possible involvement of Ca2+ in the intracellular movement and/or structural integrity of the chromatoid body is discussed.

Animals↗
PubMed1989

Cyclic AMP- and cytochalasin B-induced arborization in cultured aortic smooth muscle cells: its cytopharmacological characterization.

The present study analyzed effects of dibutyryl cyclic AMP (DB-cAMP) and cytochalasin B (CB) on the morphology of cultured aortic smooth muscle cells (SMC) from rat using phase-contrast microscopy, scanning electron microscopy, and fluorescence staining of actin filaments by the NBD-phallacidin method. The exposure of SMC to each of these agents led to rapid, extensive, and reversible (within 1-2 h of drug withdrawal) changes in their morphology including cytoplasmic arborization (stellation). The latter was preceded by (i) marginal membrane ruffles (DB-cAMP) and (ii) increased zeiotic activity (CB), which were visible within 20 min of the exposure, followed (30-90 min incubation) by a centripetal retraction of the cytoplasm and progressive development of complete or partial arborization. Further, the effects of substances interfering with the assembly-disassembly of microtubules (colchicine, taxol, lidocaine) on DB-cAMP- and CB-induced arborization were studied. None of these agents antagonized CB-induced morphological changes. Colchicine, but not lumicolchicine, taxol, or lidocaine (in a short-term study) prevented DB-cAMP-induced arborization. Taxol added to cell cultures for 24 h promoted DB-cAMP-induced arborization. Both DB-cAMP and CB resulted in the disintegration of actin filaments. The present data suggest that the arborization of cultured aortic SMC is a cytoskeleton-based process involving stabilization of microtubules and disintegration of actin filaments. Our study also suggests that the SMC arborization may represent an in vitro case of SMC stellation found in situ.

Actins↗
PubMed1989

A new view of the arterial smooth muscle cells and autonomic nerve plexus by scanning electron microscopy in spontaneously hypertensive rats.

Mesenteric artery smooth muscle cells and their associated autonomic nerve plexus were simultaneously studied by scanning electron microscopy in 3-month-old spontaneously hypertensive rats. The adventitial surface of the outermost muscle layer revealed numerically more protrusions accompanied by a denser network of nerve fibers in spontaneously hypertensive rats vs normotensive Wistar-Kyoto rats.

Animals↗
PubMed1988

Phorbol 12-myristate 13-acetate prevents isoproterenol-induced morphological change in cultured vascular smooth muscle cells.

The effect of phorbol 12-myristate 13-acetate (PMA) on isoproterenol (ISO)- and dibutyryl cAMP (dBcAMP)-induced morphological change and cytoskeletal reorganization was studied in cultured vascular smooth muscle cells (VSMC) using the fluorescence staining of actin and microtubules. The treatment of VSMC with 1.0 microM of ISO or with 1.0 mM of dBcAMP for 90 min induced the disruption of actin-containing stress fibers followed by cytoplasmic arborization. The addition of 100 or 10 nM of PMA prevented both the destruction of actin fibers and cell arborization induced either by ISO or by dBcAMP. However, PMA rather enhanced cAMP production stimulated by ISO. 1-Oleoyl-2-acetyl-sn-glycerol (100 micrograms/ml) mimicked this inhibitory effect of PMA whereas 4 alpha-phorbol 12,13-didecanoate (100 nM) failed to block the arborization. These results indicated that the inhibition of arborization by PMA was mediated through the activation of protein kinase C. Colchicine at 5.0 microM also had an inhibitory effect on ISO- and dBcAMP-induced cell arborization. However, immunofluorescence studies revealed that colchicine but not PMA elicited the reorganization of microtubules, suggesting that the effect of PMA was mediated through a mechanism different from that of colchicine. These observations indicated that the morphology of VSMC was regulated through the alteration of cytoskeletal organization induced by cAMP-mediated and by protein kinase C-dependent systems.

Actin Cytoskeleton↗
PubMed1988

Golgi-cilium complex in rabbit ciliary process cells.

We report here on a structural association of single cilia, via their striated rootlets, with the Golgi complex in epithelial cells and stromal fibroblasts of rabbit ciliary processes of the eye. The structure is designated a Golgi-cilium complex and its likely role in aqueous humor production is discussed.

Animals↗
PubMed1988

Collagen in the aortae of spontaneously hypertensive (SHR) rats.

A biphasic pattern of collagen biosynthesis was found in the aortae of spontaneously hypertensive (SHR) rats; the time course of the rate of biosynthesis is similar to that described in the heart by Sen and Bumpus. In comparison to age-matched controls, collagen biosynthesis is elevated in the SHR rats, diminishes during the first fourteen weeks and rises again at the stage of established hypertension. In the period of established hypertension, the increased rate of collagen biosynthesis was associated with a pronounced rise of the collagen type I to type III ratio. On the other hand, in the pre-hypertensive stage, the proportion of collagen type III clearly exceeds the proportion of collagen type I in SHR rats.

Animals↗
PubMed1987

Effect of colchicine on the ultrastructure of secretory-state smooth muscle cells from the rabbit artery wall.

Little is known about the possible role of microtubules and related structures with respect to the structural and functional heterogeneity of arterial smooth muscle cells (SMC). This study demonstrates that a short-term treatment with an antitubulin, colchicine, resulted in two major structural changes in arterial SMC in the aortic arch, the thoracic aorta and the pulmonary trunk of 20-d-old rabbits. The SMC of control rabbits showed well-developed rough endoplasmic reticulum and Golgi complexes, and numerous microtubules. Colchicine treatment affected (a) microtubules in a monotypic way (all SMC contained no microtubules after colchicine), and (b) Golgi complexes and rough endoplasmic reticulum in a pleiotypic way. In effect two major structural subpopulations of SMC were obtained; the first subpopulation displayed markedly altered Golgi complexes, whereas the rough endoplasmic reticulum was unaltered; the second subpopulation showed a vacuolar dilation of rough endoplasmic reticulum (or extensively-developed smooth sarcoplasmic reticulum), but a disappearance of Golgi complex. These data suggest that an organelle-specific sensitivity to colchicine (most likely to its antitubulin action) may contribute to the heterogeneity of SMC. They also suggest that within control SMC two subpopulations might exist which can only be detected under special conditions like colchicine treatment. The disassembly of microtubules detected in parallel may be one trigger, but not the main mechanism in the heterogeneous changes of SMC in reaction to colchicine.

Animals↗
PubMed1985

Colchicine-induced appearance (proliferation) of smooth sarcoplasmic reticulum in arterial smooth muscle cells.

Colchicine treatment resulted in the appearance and proliferation of smooth sarcoplasmic reticulum in some smooth muscle cells of the aortic and pulmonary trunk walls in the rabbit. The significance of cytoplasmic microtubules and/or membrane-bound tubulin for the morphogenesis, functioning and control of smooth endoplasmic reticulum in different kinds of cells is discussed.

Animals↗