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Biomedical subjects

B Fortier

Publications and source records attributed to B Fortier.

At least 55 records · Page 3Linked to original sources
PubMed1987

Immunochemical analysis of a major antigen of Plasmodium falciparum (P126) among ten geographic isolates.

Protein P126, a parasitophorous vacuole major antigen of Plasmodium falciparum and precursor of 3 major exoantigens (50, 47, and 18 Kd in strain FCR-3) has been studied in 10 culture-adapted isolates originating from various endemic areas. Two monoclonal antibodies (specific for 50 and 47 Kd exoantigens, respectively) were used to immunoprecipitate culture supernatants and parasitized erythrocytes in each case. It was observed that all the parasite isolates reacted with both monoclonal antibodies, indicating the ubiquity of the epitopes analyzed. Further, two of the exoantigens (the 50 and 18 Kd of FCR-3) were found to have a stable molecular mass in all the isolates tested, whereas, the other one (47 Kd in FCR-3) was found to have a variable molecular mass, from 47 to 50 Kd. The molecular mass of the precursor varied from 126 Kd to 128 Kd. No correlation was found between geographic origin and antigenic size.

Antibodies, Monoclonal↗
PubMed1986

A monoclonal antibody to a cell wall component of Candida albicans.

A heterologous fusion between mouse myeloma cells and rat lymphocytes resulted in the isolation of a rat immunoglobulin M monoclonal antibody with both agglutinating and precipitating activity. Indirect immunofluorescence and direct agglutination tests showed that the corresponding antigen was present in the cell wall of the three Candida species considered to be the most pathogenic, C. albicans, C. tropicalis, and C. glabrata, and also in the cell wall of C. guilliermondii. The antigen appeared to be predominantly polysaccharide in nature. Precipitation by counterimmunoelectrophoresis suggested that the epitope is shared by at least two separate molecules with different electrophoretic mobilities. Presence of this epitope varied from strain to strain within a given species and may be related to the morphological stage in the cell cycle. Antigen was shown to be present in the cytoplasm, in the periplasmic space, and at the cell surface of C. albicans. Indirect immunofluorescence also suggested that antigen is excreted from the cell.

Agglutination↗
PubMed1986

Identification of distinct accumulation sites of 4-aminoquinoline in chloroquine sensitive and resistant Plasmodium berghei strains.

We report the synthesis of an analogue of chloroquine (CQA) which can be used as a probe to visualize accumulation of 4-aminoquinoline by electron microscopy. A mouse monoclonal antibody against CQA was raised and used for immunodetection by the protein-A gold method on ultrathin cryosections, of CQA treated parasites. We demonstrate that in a P. berghei chloroquine(CQ)-sensitive strain (N strain) the chloroquine analogue used accumulates in the endocytic vacuoles where hemoglobin (Hb) degradation is occurring. In contrast, in a P. berghei CQ-resistant strain (RC strain) the probe was found scattered all over the cytoplasm of the parasite. This result suggests that endocytic vacuoles of the parasite could constitute the site of antimalarial action of CQ.

Aminoquinolines↗
PubMed1985

A 50 kilodalton exoantigen specific to the merozoite release-reinvasion stage of Plasmodium falciparum.

The immunoglobulins G of a human plasma inhibiting in vitro Plasmodium falciparum merozoite reinvasion have been purified and used to immunoprecipitate the antigens released into the culture medium by an [35S]methionine-labeled synchronous culture. Several of the major exoantigens identified were found throughout the entire life cycle; they were also immunoprecipitated from the labeled parasitized cells. Some antigens were found only after the reinvasion stage, and especially a major one of molecular mass 50 kDa and pI 5.5. The latter was not found in the parasitized cells but derived most likely from the processing of a major 126 kDa antigen which disappeared from the parasites during the reinvasion period and which was immunoprecipitated by an anti-50 kDa monoclonal antibody.

Antigen-Antibody Complex↗
PubMed1985

[Pneumococcal vaccination of the pregnant woman in Africa and passive immunity of the child. Immunologic control by the ELISA method].

Thirty-seven african women (mean: 23 years old) were immunized with a pneumococcal vaccine and tetanus vaccine, in a comparative study with seventeen (mean: 24 years old) women only tetanus immunized. Immune response to pneumococcal polysaccharide was studied by ELISA. All women had antibodies before vaccination. Their kinetics in mothers and infants, did not show a significant difference between the two groups. In infants, the rate of IgG antibodies significatively decreases from the date of birth to the fourth month of life. There is no foetal immunisation as shows the total lack IgM antibodies in umbilical cord blood. These results suggest that pneumococcal vaccination pregnant women in order to protect infants till 6-9 months, is not valuable.

Adult↗
PubMed1985

[Contribution and current limitations of computed tomography in the diagnosis of cavernous hemangioma of the liver].

Based on findings for 30 patients, the authors assess the value of CT scans for the diagnosis of cavernous hemangiomas of the liver. Four images were retained, and were graded 0 (absence) or 1 (presence): hypodensity before injection of the contrast material, arteriolar halo after injection, progressive centripetal filling and late hyperdensity. A score of 3 or 4 after the CT scan allows diagnosis. Solitary lesions of at least 3 cm are correctly evaluated. When associated with other smaller lesions, or when smaller than 3 cm, CT scans are less helpful and arteriography is necessary. In all. CT scanning has four limiting parameters: lesion diameter, the number of images requiring exploration, the difficulty in obtaining exactly the same section in various sequences allowing effective scan analysis (thoraco-abdominal position of the liver) and problems specific to individual patients (poor circulation, iodine allergy or intolerance). These limiting factors explain the "wait-and-see" strategy suggested when confronted with solitary hyperechoic nodules smaller than 3 cm.

Female↗
PubMed1983

Isolation of a human pararotavirus.

During a survey of 350 different isolates of human rotaviruses, a single isolate with unique properties was obtained. Unlike all rotaviruses tested this unique isolate failed to react in an ELISA test with antibody directed against the group-specific rotavirus antigen. The morphology of this unusual virus isolate was identical in electron micrographs with other rotaviruses and the virus also contained 11 double-stranded RNA segments characteristic of this virus group. The electrophoretic migration of these RNAs (electrophoretype) in polyacrylamide gels did not coincide with the typical pattern of distinct size classes observed with all human rotaviruses. The unique isolate thus had two distinct properties that distinguish it from human rotaviruses, lack of a group-specific antigen and an atypical electrophoretype of the RNA segments. Based upon this, the new human isolate is given the name pararotavirus to distinguish this new type of virus group. Porcine and chicken pararotaviruses have recently been described with similar properties.

Antigens, Viral↗
PubMed1983

[Detection of rubella-specific IgM by an immunoenzyme technic].

An enzyme-linked immunosorbent assay (ELISA) was compared to sucrose gradient centrifugation technique for rubella specific IgM detection of 114 sera. The 28 sera which were rubella specific IgM positive, were also positive by ELISA. Among the 86 sera which were rubella IgM negative by centrifugation, 6 were equivocal and 2 were rubella IgM positive by the ELISA test, without clinical or epidemiological connection. These false results make a necessity of confirming by an immunoglobulin separation technique the ELISA IgM positive sera.

Adult↗
PubMed1982

A one-year virological survey of acute intussusception in childhood.

A prospective study was carried out during 1 year in order to correlate intussusceptions in childhood with a viral infection. A virus was incriminated in 50% of the 64 patients in this survey. Adenovirus infections remain predominant as compared to rotavirus infections.

Adenoviridae Infections↗
PubMed1982

Comparison of an ELISA technique with quantal micro-neutralization test for serotyping of HSV-1 or HSV-2-infected patients.

An enzyme-linked immunosorbent assay (ELISA) using semi-purified herpes simplex antigens extracted from cell nuclei was employed for typing of 32 sera collected from patients infected with HSV-1 or HSV-2. The results were in agreement with those obtained by the quantal micro-neutralization test. Moreover, sera with antibodies which could not be detected by micro-neutralization test could be typed by the ELISA technique according to the HSV isolates.

Antibodies, Viral↗
PubMed1982

Antibody determination by ELISA in rats with retinal S antigen-induced uveoretinitis.

Enzyme-linked immunosorbent assay was applied to the determination of the serum IgG antibody contents in rats immunized with the organ-specific autoantigen (S antigen) of the retina. Optimal conditions (i.e. S antigen concentration, serum and conjugate dilutions, enzymatic reaction time) were determined. The assay required only a single serum dilution and was well reproducible. It was very sensitive, allowing the detection of low antibody contents in animals immunized with 1 microgram of S antigen. The time course of the antibody response and its variations according to the dose and the species of the immunizing S antigen were considered.

Animals↗
PubMed1982

[Value of the immunoenzyme method (ELISA) in determining serum and aqueous humor antiherpes immunoglobulin levels (apropos of 155 cases)].

Immuno-enzymatic assay of aqueous humor and serum antiherpetic antibodies was performed in 155 patients with all types of uveitis and with keratitis. Globulin levels were also determined in the two fluids, employing an original nephelometry-laser technique. This immuno-enzymatic technique, which possesses greater reliability, reproducibility, and sensitivity than passive hemagglutination, appears suitable for microassay in aqueous humor, and demonstrates the production of anti-herpes antibodies in this fluid to the exclusion of other specificity. Applying limits of at least 1/40e for H.A. antibody levels, and at least 10 for the immunity load coefficient, these antibodies could be demonstrated in half of the cases of clinically confirmed herpes, in one-third of clinically suspected cases, and in two intermediary cases of uveitis where no predictive signs of herpes were present. In contrast, specific antibodies were never detected in 70 cases of anterior or total uveitis. Measuring anti-herpes antibodies in aqueous humor and serum by the ELISA method, in association with immunity load coefficients determination in the two fluides, appears to be a very useful method for the future etiological diagnosis of anterior and intermediary uveitis when the etiology is uncertain but clinical signs suggest a possible herpetic origin.

Adolescent↗
PubMed1981

[Use of Staphylococcus aureus protein "A" to detect rotavirus in the stools (author's transl)].

The authors have used an anti-rotavirus immunserum fixed to the Staphylococcus aureus protein A to detect this virus in the stools. A study on animal faeces showed a very good agreement in results with ELISA technique. The study on human stools shows a good agreement with ELISA technique and identical results to this technique in comparison with electronical microscopy. The agglutination reaction appears as a quick, simple and specific technique to find out rotavirus in the stools.

Agglutination Tests↗
PubMed1980

[Studies of immunological status, following autologous bone marrow transplantation in man (author's transl)].

Following transplant, circulating immunoglobulin levels fell moderately and remained depressed less than 2 months for IgG, and for variable and longer periods of time for IgM and IgA. Repeated quantitative determinations of antibodies against multiple antigens did not show any decrease in the pretransplant levels. Indeed some patients developed herpes and cytomegalovirus infections to which they responded by a sharp increase in antibody titers. In 2 cases, a primary immunization was demonstrated (against CMV and BK virus) with increasing levels of IgM and IgG antibodies. Lymphocyte counts in peripheral blood returned to 500 mm# between day 10 and 29 (median day 18) and to pretransplant values within 6 weeks. Non specific stimulation of lymphocytes by mitogens in the immediate post-transplant period showed a decreased response to PHA and Con A, whereas the responses to pokeweek mitogens and alloantigens were only slightly diminished. The degree of the responses was related to the dose of cryopreserved marrow infused. We conclude that:--although the minimum dose for autologous bone marrow transplantation in man is around 0,5 10(8) nucleated bone marrow cells/Kg, much higher doses should be used to ensure faster and better restoration of immune reactivity.--The similarity of the immunological dysfunction following autologous and allogeneous bone marrow transplantation suggest that, in the immediate post-transplant period, the role of GVHD in cellular immunity depression may be minimal.

Bone Marrow Transplantation↗