Effect of vasoactive amines on Weibel-Palade bodies in capillary endothelial cells

The presence and distribution of Weibel-Palade bodies in stomach and colonic mucosal microvessels after the administration of vasoactive amines (serotonin and histamine), the serotonin depletor reserpine, and the von Willebrand factor secretagogue thrombin, was studied by transmission electron microscopy. These agents elevated the number of Weibel-Palade bodies in all microvascular endothelial cells and especially in capillaries. It is concluded that vasoactive amines enhance the synthesis and secretion of large von Willebrand protein multimers by endothelial cells.     

Effect of temperature on in vitro proliferative activity of human umbilical vein endothelial cells

Human umbilical vein endothelial cells, skin fibroblasts, and retinal pigment epithelial cells are cultivated in medium supplemented with 15 to 20% serum in our laboratory. The effects of various incubation temperatures on the proliferation of these cells was examined. Our study shows that the mitogenic response of the endothelial cells to a change of temperature differed markedly from that of the fibroblasts and epithelial cells. Cultivation of human umbilical vein endothelial at 37°C required seeding densities as high as 1–2×10⁴ cells/cm², and yet resulted in a low growth rate and premature senescence. However, under the same culture conditions, but at 33°C, the proliferative capacity of these endothelial cells was potentiated. The results were striking; at 33°C the cells grew actively and the life span was extended. The number of cumulative population doublings increased fourfold compared with that for the same cells cultivated at 37°C. The inoculum size could be reduced, since at 33°C the endothelial cells were able to replicate at seeding densities as low as 20 cells/cm². The cells serially subcultured at 33°C retained morphological features and specific immunological markers of endothelial cells.     

Effect of adrenergic amines on the membrane potential of guinea-pig liver parenchymal cells in short term tissue culture

Zusammenfassung Mit Hilfe der intrazellulären Mikroelektrodentechnik wirk gezeigt, dass Parenchymzellen der Meerschweinchenleber in der Gewebekultur hyperpolarisieren, wenn sympathomimetische Drogen ionophoretisch appliziert werden.     

Nuclear multivesicular bodies in cultured hamster cells

Zusammenfassung Mit elektronenmikroskopischer Untersuchung von BHK 21 cl 13 Zellen wurden multivesikuläre Körperchen im Karyoplasma festgestellt, Strukturen, die direkt der inneren Kernmembran entstammen. Die multivesikulären Körperchen wie auch die internen vesikulären Elemente ( 90 nm) waren von einer einzigen Membran umgeben.

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Acknowlegdment: we thank Miss.P. Martinez Venteo for her excellent technical assistance.     

Argyrophilic intranuclear bodies of plant cells

Summary Within interphase nuclei of meristematic cells of plants there are small spherical bodies that stain intensely with silver. Their number is related to the DNA content of the species.     

Further studies on endothelial cells of vertebrates and the problem of endothelial granules

Resumen Se describe la ultraestructura de células endoteliales de aorta abdominal de murciélago, foca y pinguino y se discuten los resultados en función de estudios precedentes nuestros y de otros autores sobre esas células en differentes especies. La presencia, o ausencia, y frequencia de los gránulos citoplasmáticos en las células endoteliales en las especies estudiadas parecería la expressión de un proceso evolutivo a nivel de clases.     

Effect of a magnesium-deficient diet on the striatal content of amines in the dog

Résumé Une diète déficiente en magnésium administrée à de jeunes chiennes pendant 35 jours est suffisante pour produire une diminution significative de la concentration en dopamine du noyau caudé, mais non des autres amines mesurées. Cliniquement les animaux étaient hypokinétiques, mais ne tremblaient pas. Cette approche expérimentale pourrait s'avérer utile dans l'étude de la pathophysiologie de l'hypokinésie.     

Effect of biogenic amines on γ-amylase (acid α-glucosidase)

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Angiogenesis and signal transduction in endothelial cells

Endothelial cells receive multiple information from their environment that eventually leads them to progress along all the stages of the process of formation of new vessels. Angiogenic signals promote endothelial cell proliferation, increased resistance to apoptosis, changes in proteolytic balance, cytoskeletal reorganization, migration and, finally, differentiation and formation of a new vascular lumen. We aim to review herein the main signaling cascades that become activated in angiogenic endothelial cells as well as the opportunities of modulating angiogenesis through pharmacological interference with these signaling mechanisms. We will deal mainly with the mitogen-activated protein kinases pathway, which is very important in the transduction of proliferation signals; the phosphatidylinositol-3-kinase/protein kinase B signaling system, particularly essential for the survival of the angiogenic endothelium; the small GTPases involved in cytoskeletal reorganization and migration; and the kinases associated to focal adhesions which contribute to integrate the pathways from the two main sources of angiogenic signals, i.e. growth factors and the extracellular matrix.Received 13 February 2004; received after revision 25 March 2004; accepted 19 April 2004     

Pharmacological attenuation of apoptosis in reoxygenated endothelial cells

BRX-235 (Iroxanadine), a novel drug developed by Biorex (Hungary), was previously characterized as a vasculoprotector against atherosclerosis, an activator of p38 kinase, and an enhancer of stress-responsive heat shock protein (Hsp) expression. The present data demonstrate that BRX-235 may improve survival of vascular endothelial cells (ECs) following ischemia/reperfusion stress. ECs cultured from human umbilical veins were exposed to hypoxia/reoxygenation to mimic ischemia/reperfusion. Caspase activation and apoptosis were monitored in the reoxygenated cells. Addition of BRX-235 (0.1–1 M) to culture medium prior to hypoxia or at start of reoxygenation significantly reduced the caspase-dependent apoptosis. The cytoprotection conferred by the pre-hypoxic drug administration was sensitive to quercetin and seems to be based on enhanced Hsp accumulation in stressed ECs. In the case of post-hypoxic drug administration, the cytoprotection was strongly inhibited by SB202190 and SB203580 and appears to be associated with enhanced p38 kinase activation in reoxygenated ECs.Received 12 May 2004; received after revision 7 September 2004; accepted 24 September 2004     

Effect of imipramine on the norepinephrine and histamine-induced capillary response in the rat

Résumé Les résultats rapportés nous autorisent à postuler l'hypothèse que la norépinéphrine est un inhibiteur hormonal naturel dans les premières phases de la réaction inflammatoire et que l'imipramine et la désipramine, qui empêchent l'accumulation de la norépinéphrine dans les réserves, augmentent et prolongent l'action de la norépinéphrine sur le réseau capillaire. En aucune façon les effets de l'imipramine sur le réseau capillaire se sont montrés différents de ceux causés par la désipramine.

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This work was partially supported by grants from the Ministry of Health of the Province of Quebec (Federal-Provincial Health Research Grants).