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Biomedical subjects

D Lavanchy

Publications and source records attributed to D Lavanchy.

11 recordsLinked to original sources
PubMed1992

[Prevalence of anti-HCV (C100-3) antibodies in 20.373 blood donors].

The anti-HCV antibody (C100-3) is present in the serum of 70-90% of patients that are carriers of posttransfusion non-A non-B hepatitis. This marker appears to be associated with a viral replication and infectiousness state. Since 1st August 1990 the Swiss Red Cross Transfusion Service has operated a systematic search for anti-HCV antibodies for every blood donation. The aim of the study was to establish the prevalence of anti-HCV antibodies in a donor population, look for the risk factors in the anti-HCV positive group, look for biological symptoms and signs of chronic hepatitis, and compare the data with that from an anti-HCV negative control group. From August to March 1991, 20,373 donors were tested by EIA (Ortho). The presence of anti-HCV antibody was confirmed by a neutralization test (Abbott). The donors in which both tests were positive formed the group studied (55 subjects). Their data was compared with that of a control group of anti-HCV negative donors. The prevalence of anti-HCV antibody in the group of 20,373 donors was 0.29%. Possible parenteral exposure to hepatitis C virus was found in 47% of anti-HCV positive subjects (30% blood transfusion, 9% i.v. drug addiction, 8% tattooing). 42% of the anti-HCV positive donors had no risk factor presently known for hepatitis C. 27% of anti-HCV positive donors had elevated transaminase levels. Until more effective screening tests are introduced it appears necessary to stress the previous history of future blood donors in order to search for hepatitis C risk factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Donors↗
PubMed1990

Modified dot assay with increased sensitivity: detection of small amounts of immunoglobulin molecules and the importance of different detection systems.

The original method of the dot assay described by Hawkes et al. enabled the detection of 100 pg of immunoglobulin molecules. We compared different enzyme detection systems based on the avidin-biotin complex, in conjunction with different substrates. Three commercial kits (Vectastain-ABC, Streptavidin Bridge, and Streptavidin-Peroxidase Complex) based on the same technique were also included in the comparison. In addition, we tested the Aureo-Probe kit, which is based on gold- and silver-enhanced staining. Various incubation times, blocking solutions (horse serum, bovine serum albumin, and milk), and commercial antihuman Ig antisera or monoclonal antibodies were tested. The greatest sensitivity was achieved by using the peroxidase-avidin-biotin complex together with 4-chloro-1-naphtol as substrate, which detected 1 pg of immunoglobulin molecules. Equal sensitivity was also shown by the Aureo-Probe system.

Avidin↗
PubMed1987

Monoclonal antibodies to the multienzyme enniatin synthetase. Production and use in structural studies.

Monoclonal antibodies have been prepared against the multifunctional enzyme enniatin synthetase, which catalyses the biosynthesis of the cyclodepsipeptide antibiotic enniatin. Five different antibodies (designated 1.56, 21.1, 25.91, 28.7 and 28.34) were characterized. 1.56, 21.1 and 25.91 were of IgG1 and 28.7 and 28.34 of IgM subclass. Binding studies showed that 21.1 and 25.91 are obviously directed against determinants based on the primary structure of the enzyme, whereas 28.7, 28.34 and 1.56 bind to the native enzyme. All antibodies inhibited enniatin formation. Based on their ability to inhibit different partial reactions of the multienzyme the antibodies could be divided into three groups: 21.1 and 25.91 inhibit valyl thioester formation, 1.56 additionally inhibits D-2-hydroxyisovaleric acid thioesterification, and 28.7 and 28.34 block both thioester sites as well as the N-methylation step. None of the antibodies affected the formation of L-valyl or D-hydroxyisovaleryl adenylate by the enzyme. The results indicate that there must be distinct thioester activation sites for valine and D-hydroxyisovalerate close to each other and in the neighbourhood of the methyltransferase site. The adenylation sites for D-hydroxy-isovalerate and L-valine are obviously located at some distance.

Affinity Labels↗
PubMed1978

[Lymphocyte stimulation in various age groups].

The study of lymphocyte functions is of great significance for evaluation of the immune response. One of the most valuable assays being the mitogenic response of lymphocytes to different antigens or mitogens, the question of the extent to which lymphocyte response decreased with advancing age has been studied. Peripheral blood lymphocytes from healthy individuals aged 21 to 97 years were assayed for the blastogenic response to different mitogens. A significant age-dependent reduction of lymphocyte stimulation could be observed with two of the three mitogens tested. Since these mitogens in the concentrations used are mainly T lymphocyte stimulators, it can be concluded that an age-dependent reduction in T lymphocyte functions is present. These findings are not only of diagnostic significance but also have therapeutic implications for all geriatric diseases in which immunity may play a role. Furthermore, the experiments described show that the lymphocyte transformation assay with different mitogens is a simple reproducible assay which has its place in every routine evaluation of the immune response system.

Adult↗
PubMedDate not supplied

Immune response to purified non-A, non-B hepatitis-related antigen demonstrated by leukocyte migration inhibition in patients recovering from the infection.

Eight patients, convalescent from acute hepatitis, all negative for HBsAg, anti-HBc, anti-HA-IgM, anti-CMV and anti-EB, and all positive for non-A, non-B related antigen and/or antibody in at least one sample during the course of disease, were investigated. Their specific cell-mediated immunity was tested using the leukocyte migration inhibition test in presence of a previously described non-A, non-B related antigen. A control group consisted of ten individuals (two normal subjects, six patients recovering from acute hepatitis B and two with autoimmune chronic active hepatitis). Leukocyte migration was inhibited by the antigen in seven of the eight patients. The test was negative in all control subjects. It is thus demonstrated that after recovery, patients with non-A, non-B viral hepatitis develop a cellular immune response specific for purified non-A, non-B related antigen. The association between the described antigen and viral hepatitis non-A, non-B can now be established not only by immunoprecipitation, but also by a cellular test.

Adult↗
PubMedDate not supplied

Anti-pre-S2 antibody response in subjects vaccinated against hepatitis B and in naturally immunized subjects.

Serum samples from individuals immunized with a pepsinized or non-pepsinized vaccine and from patients who had recovered from acute hepatitis B or who developed a chronic form of the disease, were analysed for the presence of antibody against the pre-S2 epitope of the hepatitis B virus. Anti-pre-S2 antibody was absent in all but one individual immunized with the pepsinized vaccine. Thirty-eight percent of the subjects who responded by anti-HBs production to the non-pepsinized preparation showed anti-pre-S2 antibody one year after complete vaccination. Among subjects who did not produce anti-HBs after immunization with this vaccine, 1 single individual produced anti-pre-S2 antibody. Anti-preS2 antibody was detectable after one year in 38% of the patients who recovered from acute hepatitis B, but in none of those with chronic hepatitis B. The kinetics of anti-pre-S2 antibody response to a booster injection was also analysed 1 month and 1 year after the 3rd injection and 1 month after the 4th injection of the non-pepsinized vaccine.

Acute Disease↗