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Biomedical subjects

M Brossard

Publications and source records attributed to M Brossard.

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

Na fluxes in human mononuclear leucocytes.

Unidirectional 22Na fluxes were investigated in human peripheral mononuclear leucocytes. Ouabain inhibited about 60% of Na efflux and the addition of bumetanide further reduced Na efflux rate by about 45%, suggesting the presence of a transport pathway capable of extruding Na against its gradient. Prostaglandins E1 and E2 and exogenous cAMP were found to be potent inhibitors of the bumetanide-sensitive Na efflux without affecting the ouabain-sensitive or the ouabain and bumetanide resistant Na effluxes.

1-Methyl-3-isobutylxanthine↗
PubMed1986

Irreversible changes in rat erythrocyte Na+ transport systems with progesterone and estradiol administration.

In order to test whether alterations in Na+ transport systems occurring in women when the hormonal status is disturbed such as in pregnancy, under contraceptive or estradiol therapy are a direct result of hormonal action on these transport systems, Na+,K+-pump Na+,K+ outward cotransport and passive Na+ permeability were measured in erythrocytes of ovariectomized rats receiving estradiol or progesterone. No significant changes in Na+,K+-pump were observed in either conditions. Conversely, progesterone was found to decrease Na+, K+-cotransport and estradiol to increase this system, whereas both steroids increased passive Na+ permeability.

Animals↗
PubMed1985

Modulation of erythrocyte Na transport pathway(s) by excess Na intake.

Different Na transport pathways were studied in the erythrocytes of 10 normotensive subjects who received 240 meq/day of Na in excess of their usual diet. In most of these subjects the maximal rate (Vmax) of the Na,K pump and the Na,K-cotransport system was markedly decreased on the first day of the diet. In some of these subjects, excess Na intake induced an increase in the apparent affinity for internal Na for the Na,K pump and the Na,K-cotransport system. The decrease in the Na,K pump fluxes was not concomitant to that of the co-transport system and not accompanied with an increase in blood pressure or cation concentration in the plasma. Interestingly, the apparent affinity for internal Li of the Li-Na exchange was markedly increased without alteration of the Vmax. The passive permeability for Na and the cellular Na content were not altered by excess Na intake. Ouabain and bumetanide at low concentrations respectively induced an increase in the apparent affinity for internal Na of the Na,K pump and the Na,K- cotransport system. These results are similar to those observed after excess Na intake. These later agree with the hypothesis that Na homeostasis regulates some endogenous factors with ouabain-like and furosemide-like properties that might contribute to the regulation of cellular Na handling.

Adult↗
PubMed1985

Immunity of dogs against Babesia canis, its vector tick Dermacentor reticulatus, and Ixodes ricinus in endemic area.

Previous epidemiological studies allowed us to accurately define endemic areas of canine babesiosis and tick distribution in southeastern France (Martinod, 1983). Using a micro-ELISA test 100 dogs sera were tested with 3 antigens: Babesia canis, Dermacentor reticulatus and Ixodes ricinus. Antibodies against B. canis and its vector D. reticulatus were detected in an endemic area, sometimes with high levels (optical density 1.38 and 0.80 respectively). A correlation factor and regression lines were found between ELISA activity of B. canis and vector tick antigens, even for dogs which never showed any babesiosis symptoms. These results were compared with those of an area without any babesiosis. Furthermore I. ricinus antigens detected ELISA activity in sera of dogs; some cross reactions were observed between I. ricinus and D. reticulatus antigen.

Animals↗
PubMed1984

Passage of hemolysins through the midgut epithelium of female Ixodes ricinus L. fed on rabbits infested or reinfested with ticks.

Antibodies considered in this study are hemolysins synthesized by rabbits against sheep red blood cells. Ingested with the blood meal, they cross the tick midgut epithelium and retain their immunological properties in the hemolymph. During a reinfestation of rabbits, more ticks present these antibodies, and titres are generally higher than during a first infestation. Hemolysins are only found in ticks weighing 180 mg or more.

Animals↗
PubMed1984

Lithium, sodium and potassium transport in erythrocytes of manic-depressive patients.

Different Li, Na and K transport pathways were assessed in erythrocytes from manic-depressive patients. No alteration in the Li-Na countertransport, Na,K cotransport or passive permeabilities was observed in either unipolar or bipolar manic-depressive patients. In addition, acute or chronic lithium treatment did not alter the maximal velocity of either the Li-Na countertransport or the Na,K cotransport. A two-fold reduction of the ouabain-sensitive Na efflux was observed among manic-depressive patients without alteration in the affinity of the Na pump for internal Na.

Adult↗
PubMed1982

Ixodes ricinus L.: mast cells, basophils and eosinophils in the sequence of cellular events in the skin of infested or re-infested rabbits.

Some information on acquired resistance of rabbits against Ixodes ricinus ticks has been obtained by comparing tissue changes and cellular infiltration during 2 successive infestations, with particular emphasis on the cells involved in immediate type hypersensitivity reactions: mast cells, basophils and eosinophils. More degranulated mast cells were observed in tick lesions 2 h after the beginning of re-infestation than in the first infestation and more degranulated basophils were present on the 5th day of re-infestation. Numerous eosinophils infiltrated the dermis, especially on the 5th day of the second infestation.

Animals↗
PubMed1982

Progressive sensitization of circulating basophils against Ixodes ricinus L. antigens during repeated infestations of rabbits.

The sensitivity of rabbit basophils to antigens from Ixodes ricinus females has been studied by a degranulation test. Observations of basophil numbers and degranulation were made on the 6th day of each of four sequential infestations. Maximal degranulation of cells was observed after challenge of cells with antigen at a concentration of 10(6) and 10(7) pg/ml. At these concentrations, during a 1st infestation, 21.8 and 23.6% of cells degranulated. During a 2nd infestation, these percentages increased (34.8 and 33.8%) and reached 59.8 and 63.8% by the 4th infestation. A plasma factor which partially blocks basophil degranulation, is described. This was already present during the 1st infestation, since in its presence the percentage of degranulation was reduced by 2.8 and 4.0% respectively on challenge with 10(6) and 10(7) pg antigen/ml. Inhibition was maximal at the 4th infestation (difference: 16.5 and 20.5%). Basophil sensitization and inhibition of the degranulation are thus both progressive phenomena. After 10-15 infestations on four other rabbits, 75.0 and 79.8% degranulation was obtained. The inhibition of degranulation by plasma was also greater (difference: 25.5 and 27.4%). IgG specific anti-I. ricinus antibodies were identified by indirect immunofluorescence. In two animals, they were detected at the 6th day of the 1st infestation. Subsequently, they were generally present for all the animals.

Animals↗
PubMed1981

[Immune response of rabbit to repeated infestations by Ornithodoros moubata Murray females: its influence on the biology of tick (author's transl)].

Antibodies against salivary gland tissues of the argasid tick, Ornithodoros moubata, were detected by indirect immunofluorescence in rabbits repeatedly fed on by ticks. This immune response appears to have little adverse affects on the biology of the tick; blood intake was found to be sometimes smaller and the feeding period somewhat longer. Attachment to the host and oviposition were not adversely affected. There exists a linear relationship between a) the weight of unfed and engorged females, and b) the weight of engorged females and the number of deposited eggs.

Animals↗
PubMed1979

Passive transfer of resistance in rabbits infested with adult Ixodes ricinus L: humoral factors influence feeding and egg laying.

Parital immunity against the bites of female I. ricinus was transferred to normal rabbits by inoculating immune serum from resistant animals. Transferred humoral factors diminished the weight of the ticks' blood meal by 29% and increased the feeding period by about 1 day in comparison with ectoparasites engorged on controls. They provoked also the failure of egg laying by female I. ricinus. Only 55% of ticks fed on treated rabbits laid eggs (94% on controls). The immunological state of immune serum donors or recipients was studied and the IgG and homocytotropic specific anti-I. ricinus antibodies were identified. The immediate hypersensitivity of rabbits' skin was also controlled.

Animals↗
PubMed1977

Effects and duration of resistance acquired by rabbits on feeding and egg laying in Ixodes ricinus L.

Rabbits gradually developed a resistance against Ixodes ricinus ticks as a result of sequential experimental infestations. The resistance was characterized by an increase duration of feeding, by ticks engorging to a smaller extent and by reduced egg production. Once established, the immunity persisted for at least 9 months. Changes in the titre of circulating anti-I. ricinus antibodies was measured by indirect immunofluorescence.

Animals↗