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Biomedical subjects

M Simonneau

Publications and source records attributed to M Simonneau.

At least 55 records · Page 3Linked to original sources
PubMed1985

Development of ionic channels during mouse neuronal differentiation.

Using a mouse embryonal teratocarcinoma (E.C.) cell line, it was possible to follow the sequence of development of ionic channels during neuronal differentiation, with patch-clamp techniques. 1003 E.C. cells were induced to differentiate into neurons by culturing them in defined medium without foetal calf serum (DARMON et al., 1981). Non-differentiated cells were not excitable and presented mainly 2 types of K+ channels: a Ca2+ activated K+ channel (220 pS in symmetrical K+) and a delayed rectifier (30 pS in symmetrical K+). When the cells start to grow neurites, a low threshold calcium current can be recorded, only if the cell is held at hyperpolarized potentials (-70 to -80 mV). Fully differentiated cells with long neurites presented a complete repertoire of ionic channels: voltage dependent Na+ and Ca2+ channels, Ca2+ activated K+ channel and K+ delayed rectifier.

Animals↗
PubMed1984

[Report of a new radioimmunologic technic for the assay of HBs antigen].

We tested a new radiometric assay (Hépatube Wellcome) using a complete automatic device, in hepatitis B surface antigen detection with I 125 marked antibody. The additional advantage of this reagent is its very long life-span (twelve weeks after the date of manufacture). The hepatube system is fully automatic, micro processor-controlled and designed to complete all washing and tracer addition steps in the hepatube test sequence after addition of the patient's sample. The results were compared in the same protocol with those obtained by the method currently used in our group (Ausria II 125). This study has been carried out on 7.589 sera or plasma samples; blood donors 5.352; medical and chirurgical patients 1.292; sera panel 87; repeated tests 367; positives and negatives control sera 421; assays ran the first day 70 The 153 positive results (2.3%) were confirmed by another assay before neutralisation. The sensitivity of both techniques was compared using a reference panel containing samples showing varying degrees of positivity, and representative of both main subtypes. We repeated the assay on this panel 2 months after issue of materials and again 3 months later. This new system is more sensitive than Ausria II 125. Of 6 644 patients the false positive was found in 1,1% of the cases, this was superior to the results found with Ausria II 125 but there is no false negative with this new method. There was no difference when serum or plasma was used.

False Positive Reactions↗
PubMed1984

[Screening of carriers of antitetanus antibodies in blood donors].

A screening of antitetanic antibody (AcAT) carriers has been carried out in 4770 blood donors. The percentage of "positive" subjects (with a rate of AcAT greater than or equal to 5 U.I./ml according to Laurell's method) is relatively high: 6,62%. The aim of a statistical study is to find out the distribution of AcAT carriers according to different factors: the chi 2 test allows us to conclude that the relation between the frequency of "positive" AcAT carriers and the blood groups is not significant but there is a significant connection between the frequency of "positive" AcAT carriers, sex and age. Our conclusions agree with those of authors having performed the study after vaccination. Our study has a double advantage: it allows us to know the vaccination state of the blood donors before any vaccination and allows the collecting of "positive" serum samples without having to wait for the vaccination.

Adult↗
PubMed1984

[Cost of transfusion in AIDS. Experience at the Claude-Bernard Hospital apropos of 28 cases].

The study of 28 confirmed cases of AIDS shows that transfused patients use a large amount of hospital's blood products, especially platelets. For these patients, the average cost of transfusion is higher than that, for intensive care unit patient's. The use of irradiated products increases the cost (+ 35%). As there is a shortage of donors, if the present precautions are respected, there is no reason why the hospital should not continue to ask the patient's family and circle of friends, to donate blood.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Distribution of receptors for acetylcholine and 5-hydroxytryptamine on identified leech neurones growing in culture.

The spatial distribution of receptors on identified leech neurones removed from the C.N.S. and grown in culture has been studied by applying acetylcholine (ACh) and 5-hydroxytryptamine (5-HT) ionophoretically and by pressure. Two cells were selected: a neurone called anterior Pagoda (Ap), that shows responses to ACh, and the pressure sensory neurone (P cell), upon which 5-HT synapses form in culture. ACh receptors of Ap neurones in culture had properties similar to those of their counterparts in situ. Thus, ACh responses of Ap cells were mediated by Cl- and were blocked by curare and alpha-bungarotoxin. The cell bodies of these neurones in culture had low (10 mV/nC) and uniform sensitivity to ACh over the surface of the soma. When a sprout grew out from the Ap cell, a region of increased sensitivity appeared at its base, with a gradient of sensitivity decreasing toward the tip of the neurite. Characteristically, the base was 3-5 times more sensitive to ACh than the soma or the growth cone. Cells with multipolar processes developed a similar pattern of sensitivity for each sprout. P sensory neurones in culture showed similar distributions of sensitivity to 5-HT and ACh. Experiments made with voltage clamp suggested that the non-uniform responses to transmitter represent true differences in sensitivity. Together these findings suggest that the receptors for ACh and 5-HT have a greater density at the base of each neurite compared to that of the soma and the tip.

Acetylcholine↗
PubMed1983

[The Duffy blood group in migrants of French-speaking Africa].

The Duffy blood types survey in 544 subjects coming from French speaking African countries, shows the high percentage of subjects having a Duffy a- b- blood type (94%). It ought to be emphasized that this predominantly Duffy a- b- population resides in areas in where there is according to the WHO data, a very low incidence of Plasmodium vivax invasion. Moreover, we have taken for another example North Vietnam, an area where there is a large Plasmodium vivax invasion and where we have found a small percentage of Duffy negative subjects (5.6%). In agreement with many authors reporting an association between Duffy negatively and vivax malarial refractoriness, this survey demonstrate that in French speaking African areas where there is a very low incidence of Plasmodium vivax invasion we have found, as expected, a high rate of Duffy negative subject.

Africa, Western↗
PubMed1981

Anti-erythrocyte autoimmunisation during chronic falciparum malaria.

Anaemia during malaria is not completely understood. Fourteen cases of antierythrocyte autoimmunisation with anti-I specificity were investigated in a Paris hospital during a period of 2 years. The patients lived in Gabon and had not been taking antimalarial chemoprophylaxis. All had chronic malaria (strongly positive antimalarial immunofluorescent antibody tests). All the recognised caused for anti-erythrocyte autoimmunity were excluded. One possible explanation for these observations is some sort of interaction between I antigen and Plasmodium, the result of which facilitated penetration of the erythrocyte by the malarial parasite.

Adolescent↗
PubMed1981

Action of colchicine on membrane currents and synaptic transmission in Aplysia ganglion cells.

The action of colchicine, a drug known to disrupt microtubules, on synaptic transmission and voltage-dependent phenomena was studied. Colchicine depressed transmission in both cholinergic and noncholinergic Aplysia ganglionic synapses. In some synapses, this effect was partly due to the curare like properties of the alkaloid. CA2+ currents, analyzed by voltage clamp techniques, were rapidly depressed by intracellular injection of colchicine and more slowly depressed by external application. Injected colchicine acted at much lower concentrations than required extracellularly. The implication of the reduced calcium influx in synaptic transmission is discussed. Colchicine caused a shift in the reversal potential of acetylcholine-activated chloride channels in a direction consistent with an increased intracellular chloride activity. It was concluded that the wide range of actions of colchicine on membrane properties should be taken into account when this drug is used in biological research.

Animals↗
PubMed1980

Quantal release of acetylcholine examined by current fluctuation analysis at an identified neuro-neuronal synapse of Aplysia.

Quantal events have been analyzed at a neuro-neuronal synapse of Aplysia where the nature of the transmitter is established and both presynaptic and postsynaptic neurons are identified and can be voltage-clamped. Prolonged depolarizations were applied to the presynaptic neuron, which gave rise in the postsynaptic cell to a current response characterized by current fluctuations or noise. Acetylcholine was also applied ionophoretically on the same postsynaptic cell. Amplitude and time course of miniature currents and acetylcholine-activated chloride channels of the same cell were examined by using a current fluctuation analysis. It was estimated that one presynaptic spike releases about 180 quanta, each opening 500 chloride channels.

Acetylcholine↗
PubMed1980

Sialic acid containing substrates as intracellular calcium receptors involved in transmitter release.

The possible function of sialic acid containing substrates in the synaptic terminals was studied by intracellular injection of ruthenium red (RuR) and neuraminidase (NAA). When injected into cholinergic and non cholinergic neurons of Aplysia, NAA and RuR, known to have similar molecular targets, blocked synaptic transmission. The subcellular sites of action of these molecules were investigated. 1. ACh receptors are not affected by RuR. 2. An intracellular site of action of RuR is likely, as less was necessary to block transmission when injected into the presynaptic cell than when applied in the bath. 3. Ca++ channels are not blocked by RuR or neuraminidase. 4. Transmission block is not due to an axonal conduction block, since strong somatic depolarization is not able to induce transmitter release in the presence of RuR. 5. Biochemical analysis of pools of 3H ACh was performed in controls and after injection of RuR. RuR appeared to significantly increase the cytoplasmic ACh pool without any change of the vesicular ACh pool. 6. Quantal release of transmitter was analysed with a current fluctuation method. There were no changes in the amplitude or decay time (tau) of miniataure postsynaptic potentials, but a decrease in the quantal content of the synapse was found.

Animals↗
PubMed1979

Transmitter release: ruthenium red used to demonstrate a possible role of sialic acid containing substrates.

1. The possible function of sialic acid-containing substrates (SACS) in synaptic terminals of Aplysia was studied by intracellular injection of ruthenium red and of neuraminidase. 2. Ruthenium red, a dye known to have sialic acid as a molecular target, blocked transmission irreversibly in both cholinergic (buccal ganglion) and non-cholinergic (cerebral ganglion) synapses. 3. An intracellular site of action is likely because much less ruthenium red was necessary to block transmission when it was injected intracellularly than when it was presented by bath perfusion. 4. Ca2+ spikes recorded in the presence of tetrodotoxin or in Na+-free solution were not modified by ruthenium red or neuraminidase injections or perfusions. It is therefore improbable that these substances blocked transmission by blocking voltage-dependent Ca2+ influx. 5. Strong electrotonic depolarization of a pre-synaptic interneurone in the presence of 10(-4) M-tetrodotoxin caused a sustained post-synaptic response, which was abolished by ruthenium red. This result eliminates axonal conduction block as the principal mechanism of ruthenium red action. 6. Post-synaptic responses to ionophoretically applied acetylcholine (ACh) were not modified by bath perfusion of 2 x 10(-2) M-ruthenium red. 7. Biochemical analysis of pools of [3H]ACh was performed after injection of a precursor, [3H]acetate, into an identified interneurone. Ruthenium red appeared to increase significantly the 'free' (cytoplasmic) ACh pool without any change of 'bound' (vesicular) [3H]ACh-pool. 8. A model is proposed in which SACS act as intracellular Ca2+ receptors involved in transmitter release.

Action Potentials↗
PubMed1978

[An acquired B antigen in a subject of A2 group].

Almost all cases of acquired B antigen have been found in individuals. This report concerns a group A2 patient with acquired B antigen. The family was not available for genetic studies. Nevertheless two facts were in favour of A2 genotype: 10 after acetylation of the patient's red cells the A1 reactivity which usually reappears or is increased on acquired B cells, did not appear. 20 The study of the serum alpha-N acetyl galactosaminyl transferase showed an optimal activity at pH7, as it is usually found in A2. The respective roles of anti acquired B antibodies, group A specific structures and bacterial enzyme properties in the occurrence of acquired B antigen are discussed.

ABO Blood-Group System↗
PubMed1978

Uncoupling of electrotonic synapses by calcium.

The degree of axo-axonal synaptic coupling between nerve cells in the buccal ganglion of Navanax was investigated in relation to intracellular ionic calcium. Increasing intracellular Ca2+ by injection of Ca2+, injection of Na+, or application of ionophore X537A produced uncoupling after at least 90 min, if metabolic inhibitor was present in the medium. Subsequent removal of the metabolic inhibitor reestablished the coupling in less than 30 min. Injected Sr2+ also mimicked the uncoupling action of Ca2+. The presence of a metabolic inhibitor alone had no effect on the coupling. These results lead to the following conclusions: (i) Uncoupling is due to an increased free Ca2+ concentration at the junctions. (ii) The liberation of endogenous sequestered Ca2+ is not sufficient to produce uncoupling except if an excess Ca2+ had been previously sequestered. The electrical synapses in the buccal ganglion of Navanax thus appear to be affected by Ca2+ in a similar way as gap junctions studied in non-neural tissues.

Animals↗
PubMed1976

[Frequency of hepatitis after extra-corporeal circulation].

In cardio-vascular surgery the risk that the hepatitis-B (H.B.) virus be transmitted was measured in 3 groups of patients (Professor Ch. Dubost), before and since systematic screening for HBS antigen in donors' blood. The same questionnaire was sent to each patient in each group 6 months after extra-corporeal-circulation (ECC), in order to determine the efficiency of HB virus screening tests. The present study gives the following results: --in the first group (no screening for HBS antigen in donors' blood), the frequency of icteric hepatitis was 6.7% (26 cases of jaundice, probably due to hepatitis viruses, out of 386 ECC); --in the second group (screening for HBS antigen in donors' blood by immuno-diffusion (often made after transfusion of fresh blood) the frequency of icteric hepatitis after transfusion of HBS antigen positive blood); --in the third groups, icteric hepatitis was less frequent (4.6%) since systematic screening for HBS antigen by counter-electrophoresis and complement fixation was performed (29 cas out of 629 ECC). Additionally, viral hepatitis appeared more frequently in men than in women, and among older patients than younger ones. Recovery was generally complete in 2 months; however, the evolution of the disease was severe in 3 cases and fatal in one case. In sum, after ECC, hepatitis still remains a frequent side-effect, compelling blood centers to use th most sensitive screening tests now available for HBS screening: radio-immuno-assay and reverse passive haemagglutination tests. As a consequence of the present study, these 2 techniques are being applied on a daily basis in our laboratory for HBS antigen screening tests are ineffective in preventing the transmission of other strains of viral hepatitis by blood transfusion.

Age Factors↗
PubMed1976

[Comparative study of technics of screening of carriers of HBs antigen].

The purpose of this study was to compare the results of 3 reverse passive haemagglutination techniques currently used by blood centers for the HBS antigen screening in donors' blood. A comparison was also made with 3 other techniques: Radio-immuno-assay (RIA), Counter-electrophoresis (CEP), Complement fixation (CF). The sera from 2.028 blood donors were screened by all those techniques, as well as 105 known sera, used as references (87 HBS antigen positive sera with different titers, 18 HBS antigen negative sera) and coming from 4 origins: NIH-Bethesda, Centre National de Transfusion Sanguine, Paris; Hôpital de la Pitié-Salpêtrière, Paris; Hôpital Broussais, Paris. The reverse passive haemagglutination techniques were shown to be slightly less sensitive than RIA and definitely more sensitive than CEP and CF, since 18 sera were HBS antigen positive with RIA (0.88%), 10 or 12 with haemagglutination (0.40-0.59%), 8 with CF (0.39%) and 7 with CEP (0.34%). The frequency of false positive results changed with the haemagglutination technique used (0.84% for WH.HBS, to 2.3% for Hepanosticon) and involved confirmatory tests (absorption and/or neutralisation). In sum, the sensitivity, specificity and practicability of the 3 haemagglutination techniques were shown to be nearly identical, with a slight but sure advantage for the WH.HBS in our experiment. Thus reverse passive haemagglutination techniques seem, at the present time, to be the best ones for HBS antigen screening when RIA cannot be applied.

Carrier State↗