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Biomedical subjects

M Doly

Publications and source records attributed to M Doly.

At least 55 records · Page 3Linked to original sources
PubMed1986

An automatic stimulus generation system for electroretinogram capture and processing.

An automated system is presented for on-line capture and processing of the analog signal obtained in response to light or X-ray stimulation of isolated rat retina maintained in survival by perfusion. The most important part of the system is a microcomputer Apple II (48 K Europlus) equipped with interface boards. Basic and assembler programs automatically deliver light or X-ray stimulation every 5 min. Data capture and data processing are carried out following each retinal response. Calculated parameters of the ERG, and 200 values obtained after sampling of an ERG are placed in a data file on a floppy disc. One hundred ERGs can be stored in this way.

Animals↗
PubMed1986

Experimental study of the retinal toxicity of hemoglobinic iron.

The functional consequences of vitreous hemorrhage on the retina were studied using a rabbit experimental model. The repartition of hemoglobinic iron inside the retina was assessed after the intravitreous injection of 59Fe-labeled erythrocytes. Electroretinographic studies were performed both in vivo after the intravitreous injection of labeled blood and in vitro on albino rat isolated retina treated with Fe ions. Results indicate that hemoglobinic iron migrates from the vitreous to the retina and inside the retinal tissue from ganglion cells to deeper layers. It is also demonstrated that hemoglobinic iron has a significant functional toxicity on the retina.

Animals↗
PubMed1985

Electrophysiological consequences of leukotrienes applied on isolated rat retina.

Scotopic vision is the result of a cascade of light-dependent biochemical events in rod outer segments (ROS) involving mainly a cGMP-modulation of sodium current. This modification of ionic currents induces changes of membrane potential which generates electroretinographic (ERG) waves. As (i) ERG disturbances are commonly recorded in hypoxic and inflammatory retinal diseases (ii) leukotrienes (LTs), a very potent mediators of inflammation, disturb ionic exchanges in several artificial or natural membrane systems, we undertook the investigation of the effects of LTs on ERG record in mammalian isolated retina. LTB4, LTC4 and LTD4, all induced a dose-dependent marked reduction of the b wave amplitude of ERG. This effect is correlated with a significant decrease in the survival time of the retina. The analysis of the modification of ERG indicates that LTs exhibit a real toxic effect since b wave is mainly affected while P III wave is unchanged. Comparatively with other nervous cells, this phenomenon may be attributed to an increase in Na+ permeability of ROS. It is suggested that LTs may be involved in the development of inflammatory or ischemic retinal diseases.

Animals↗
PubMed1985

Effects of leukotrienes on the electroretinographic profile of the isolated rat retina.

The isolated retina represents an excellent membrane model since it provides a specific electrophysiological response that is easy to quantify. Therefore the authors have tested the effects of B4, C4 and D4 leukotrienes on this model. In the presence of leukotrienes, electrical response generally decreases and survival duration of the isolated retina is generally shortened. No significant difference between the effects of the three tested products has been found. These results are discussed in relation to, on the one hand, the mechanism of intraretinal generation of its electrophysiological signal and, on the other hand, the leukotrienes' role in inflammatory diseases of the retina.

Animals↗
PubMed1985

[Effects of oxygenated free radicals on the electrophysiological activity of the isolated retina of the rat].

Particularly rich in polyunsaturated fatty acids, the retina constitutes an excellent model for testing the functional consequences of membrane lipoperoxidation. The effects could be quantified by measuring the amplitude of the electroretinogram which represents the characteristic response of the retina to its physiological stimulus (light photons). The authors report results obtained on isolated rat retina maintained in survival by perfusion. The membrane lipid peroxidation is induced by the non enzymatic catalytic system (Fe2+ + ascorbate). In the presence of such a system, the amplitude of the b-wave of the electroretinogram rapidly decreases and the survival time is notably shortened. These results are discussed with regards to the mechanism generating the electroretinogram and the specific role played by the disk membrane and plasmic membrane of the rod outer segment. Finally, the authors test the radical scavenger properties of a Ginkgo biloba extract. The results indicate that such an extract develops an antiperoxidative effect probably connected with its flavonoid composition. With this extract the survival time of the isolated retina is significantly increased and this result could be related to the retinal cell membrane disorders observed in diabetes.

Animals↗
PubMed1984

Effects of lipid peroxidation on the isolated rat retina.

The effects of membrane lipid peroxidation are determined in isolated albino rat retina. Lipoperoxidation induced by addition of Fe2+ + ascorbate to the perfusion liquid leads to an irreversible decrease of amplitude in the electroretinogram. The experimental model proposed here provides the possibility to monitor the survival of the retina and demonstrates that ocular lipid peroxidation very notably shortens the survival time. The specific role of the rod membranes for the excitation mechanism in the retina as revealed by these experiments is discussed.

Animals↗
PubMed1983

Study of cell changes induced by radiolabelling of human lymphocytes with 99m-technetium.

With the aim of evaluating cell changes possibly induced by labelling lymphocytes with 99m-technetium (99mTc), several rosette tests and stimulation assays with mitogens have been carried out before and after radiolabelling. The results presented here show that (i) as the rosette tests are not modified statistically, the original labelling method does not seem to induce short term membrane structure modification and (ii) as stimulation by mitogens decreases after labelling with 99mTc, medium term radiation damage, linked to autoirradiation of the cells, can be evoked. This study indicates that there is reason to limit the time taken to perform scintigraphic explorations with labelled lymphocytes in man.

Cell Survival↗
PubMed1982

Labeling of human lymphocytes with 99mTc by means of stannous pyrophosphate. Scintigraphic applications.

An original 99mTc-labeling method applied to human lymphocytes is described. This technique is based on the use of stannous pyrophosphate to reduce sodium pertechnetate. The proposed procedure has two main advantages: firstly, the labeling process takes place in a neutral and buffered medium which prevents any cellular aggregation; secondly, the labeling yield obtained is compatible with scintigraphic studies in man. The influence of each parameter on the labeling quality had been studied as well as the binding stability of the technetium fixed on cells. A systematic study of lymphocyte surface markers, before and after labeling, has led to the suggestion that the labeling process seems to affect cellular membranes, probably because of the technetium binding. Finally, scintigraphic results are presented, the study being performed on eight healthy volunteers. These results are compared with those published by other authors who used either a different radioisotope or a different labeling method.

Humans↗
PubMed1982

[Induction of ovulation and pregnancy resulting from chronic and pulsatile administration of gonadotropin-releasing-hormone (Gn-RH)].

Amenorrhoea of high origin, namely hypothalamic, reflects inhibition or a drop in endogenous secretion of Gn-RH. Two patients with this trouble were treated with synthetic Gn-RH in a pulsatile way and by a continuous method. We have been using a portable reprogrammable mini-pump (Zyklomat-Ferring) connected up to an intravenous catheter which has delivered 15 to 20 micrograms of Gn-RH for one minute every 90 minutes. This treatment brought about progressive rises in serum concentrations of oestradiol and of LH. The ovulation was obtained in both women, and checked by the demonstration by ultra-sound of rupture of the dominant follicle and by estimation of plasma and progesterone levels. One of them became pregnant following this treatment. This kind of therapy seems to us to be an attractive physiological alternative for induction of ovulation.

Adult↗