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Biomedical subjects

M Tsacopoulos

Publications and source records attributed to M Tsacopoulos.

At least 73 records · Page 4Linked to original sources
PubMed1978

[Metabolic changes in the retina after experimental microembolism in the miniature pig (author's transl)].

Experimental microembolisation provokes hemodynamics and metabolic changes in the inner retina. The metabolic modifications are the consequence of focal tissue ischaemia and have as a main feature, the activation of anaerobic glycolysis. This activation produces an increase in the production of lactic acid which, in turn, causes a drop of tissular pH. Choroidal circulation maintains photoreceptors in a physiological state.

Animals↗
PubMed1978

[The role of the glial cells in the maintenance of the ionic environment of the photoreceptors of the retina of the drone (author's transl)].

A double-barrelled potassium sensitive microelectrode was used to record electrical potentials and K+ activities in the retina of the drone Apis Mellifera during stimulation with trains of flashes, 1 per sec, intense enough to produce receptor potentials of near maximal amplitude. During the stimulation photoreceptors lose about 25% of their intracellular potassium concentration. During stimulation the potassium activity in the extracellular space increased transitorily up to 20 mM and then fell to a plateau. By this time the potassium concentration increased by about 20% in the glial cells. These results suggest that the glial cells may participate in the regulation of K+ activity in the extracellular space. The increase of potassium activity in the glial cells may be a stimulus for activation of cellular metabolism.

Animals↗
PubMed1977

[The pathophysiology of retinal artery and vein thromboses (author's transl)].

The retinal blood flow is autoregulated. Retinal metabolic changes following PaCO2 and PaO2 variations, variably affect the arteriolar resistance to flow. It is postulated that PGE1 may play the role of mediator in the control of retinal blood flow. Retinal vascular obstruction leads to a circulatory disorder, but immediately physiopathological mechanisms (more or less efficient) tend to compensate again the circulatory disorder. For example, after arteriolar embolism the retrograde plasma flow starts immediately and the cells increase their anaerobic glycolytic activity to produce sufficient metabolic energy. In the case of vein thrombosis, the retrograde drainage develops collateral microvessels whose draining efficiency depends on their number and the surface of the thrombotic area.

Carbon Dioxide↗
PubMed1975

Cornea preparation for in vitro bio-pharmaceutical evaluation of ophthalmic dosage forms.

A system has been developed for a specific biopharmaceutical purpose: testing for ophthalmic preparations, the influence of formulation on drug transport through the cornea. The apparatus is a lucite cell, divided in two compartments by a clamped rabbit cornea. Physiological conditions are ensured by a supply of oxygenated perfusion medium. They are monitored by electrical conductivity and corneal thickness measurements. Reliability of the system was tested in a set of experiments.

Animals↗