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Biomedical subjects

B Mandrand

Publications and source records attributed to B Mandrand.

8 recordsLinked to original sources
PubMed1992

Oligonucleotide genotyping of HLA polymorphism on microtitre plates.

Molecular analysis of mutations and polymorphisms that are of medical importance requires both accuracy and simplicity. In organ transplantation there is a need for an HLA typing procedure that combines the remarkable accuracy of oligonucleotide genotyping with the simplicity of conventional serological typing. We describe a simple semiautomated method of HLA class II typing consisting of an oligonucleotide hybridisation assay done on microtitre plates followed by automatic colorimetric reading. Individual HLA-DR generic typing for 30 DR specificities, including subtypes of DR1, DR2, DR13, DR14, and DR52, is done on a single plate. The entire typing assay can be completed in less than 4 hours. The procedure has been validated on more than a thousand haplotypes in prospective DR typing of kidney transplant patients, leukaemic patients, and their potential donors. The simplicity of this assay makes it suitable for routine laboratory use. It can be applied to genetic testing in general, including the testing of patients with multiple mutations.

Base Sequence↗
PubMed1992

Detection of multiple types of human papillomavirus in a giant condyloma from a grafted patient. Analysis by immunohistochemistry, in situ hybridisation, Southern blot and polymerase chain reaction.

Immunosuppressed patients such as transplant recipients are known to develop multiple lesions suggestive of human papillomavirus (HPV) infection. A giant anal condyloma was obtained from a transplant patient; several fragments taken from different areas were examined for the presence of HPV DNA using in situ hybridisation, polymerase chain reaction (PCR) and Southern blot. Typical koilocytes were seen in routinely stained tissue sections, suggesting an HPV infection; furthermore, group specific HPV antigen was detected in one of four frozen fragments. Different results were obtained by in situ hybridisation according to the fragment tested. HPV types 6/11 were detected in each of the five fragments, frozen or fixed in Bouin's or formalin solutions. However, the number of HPV DNA positive cells and the intensity of the reaction greatly varied with the specimen. HPV 16 and 18 probes also reacted positively with the sample fixed in formalin; a stronger signal was observed with HPV 18 in one large focus than with HPV 16. HPV type 5 was detected in a few isolated cells of two frozen fragments. With the Southern blot technique, the profile of an HPV 6/11 was seen only in one of two frozen fragments; in this case, the bands were intense. A slight positive reaction was also obtained in one frozen fragment with HPV 16 probe. Four frozen fragments were analyzed with PCR: HPV 6/11 was detected in each fragment; HPV 18 was detected in the four samples but with different intensities; HPV types 5 and 16 did not show any positive signal. In conclusion, the lesion is an example of infection with several HPV types, demonstrated by three different techniques. This suggests the need for careful dermatological or colposcopic follow-up of transplant recipients, in order to prevent possible malignant transformation of anogenital lesions.

Adolescent↗
PubMed1992

Second signal for T lymphocyte activation: multiple targets for pharmacological modulation.

Complete T cell activation requires at least two signals. The first is delivered through the antigen-specific T cell receptor, whereas the second is generated by cognate interactions through adhesion molecules of T cells and antigen-presenting cells and/or by cytokines produced by antigen-presenting cells. The delivery of the two signals results in gene transcription, cytokine secretion, expression of new cell surface molecules including cytokine receptors, and cellular proliferation. Reference immunosuppressive agents were shown to act at different subsequent stages of T cell activation and proliferation. Among immunostimulating compounds, those which can enhance T cell responses are likely to modulate or replace the second signal in T cell activation, or alternatively, to act at later stages such as cytokine secretion, cytokine receptor expression or response to cytokine signals. For the purpose of in vitro evaluation of the activity of immunomodulators on the second signal of T cell activation, we devised a model of accessory cell depletion and reconstitution. This model allows the capacity of a given compound to enhance surface adhesion molecule expression or to trigger monocyte cytokine synthesis to be tested, and these effects to be assessed on T cell proliferation.

Adjuvants, Immunologic↗
PubMed1991

Immune response to a major epitope of p24 during infection with human immunodeficiency virus type 1 and implications for diagnosis and prognosis.

A sequential inhibition enzyme-linked immunoassay (SIEIA) using a peroxidase-conjugated monoclonal antibody reacting to the sequence AAEWDRVHP of p24HIV-1 (amino acids 209 to 217 of p55) was developed in order to detect and determine the titer of antibody to this epitope in various populations of human immunodeficiency virus type 1 (HIV-1)-positive patients. There was a good correlation between SIEIA and a commercially available competition assay that uses recombinant p24 protein and polyclonal antibody to HIV-1 antigen, demonstrating the importance of the described epitope. Analysis of sera from French patients showed a decline of antibody to the AAEWDRVHP sequence associated with the progression of AIDS. No decrease was observed with serum samples from African patients. An immune response to the epitope was detected by SIEIA early in the course of seroconversion. Although our SIEIA uses a single p24 epitope, these data are in accordance with previously published studies in which antibodies to the whole p24 were analyzed. Sera reacting to p24 only (indeterminate profiles by Western blot [immunoblot]) did not bind to AAEWDRVHP. This epitope, which is conserved between HIV-1 and HIV-2/simian immunodeficiency virus, appears to be a major antigenic domain of p24. The area containing the sequence AAEWDRVHP and the corresponding monoclonal antibody may serve as a convenient alternative to whole purified p24 and polyclonal antibody in diagnostic and prognostic assays.

Amino Acid Sequence↗
PubMed1990

Linear B-cell epitopes of the major core protein of human immunodeficiency virus types 1 and 2.

Nine murine monoclonal antibodies directed to the major core protein p24 of human immunodeficiency virus type 1 (HIV-1) were obtained and then tested by using an epitope mapping system (Pepscan) covering the whole p24HIV1 protein to characterize antigenic domains. Four different linear epitopes were identified. Monoclonal antibodies recognizing three of these epitopes also reacted to p26HIV2 in Western blotting (immunoblotting). A monoclonal antibody specific for the fourth epitope, located at position 179 to 188 of the gag polyprotein p55HIV1 (human T-cell lymphotropic virus type 3B strain), did not react with HIV type 2 (HIV-2) core proteins. The corresponding sequence is constant in all known HIV-2 and simian immunodeficiency virus (SIV) isolates, including a very divergent SIV strain from African green monkeys (SIVagm/tyo). This observation may be relevant to the phylogeny of primate lentiviruses. Two of the conserved epitopes might be immunogenic during natural infection and could therefore be used for diagnosis and prognosis purposes. These two epitopes are AAEWDRVHP and EIYKRWII, starting at positions 209 and 260 of the polyprotein p55HIV1, respectively.

Amino Acid Sequence↗
PubMed1990

Amplify or improve detection.

Quantification with accuracy at the molecular level, by simple means, is the challenge for new generations of biospecific assays. In order to reach this goal, it is necessary to reduce the non-specific background of the current assays and further to amplify the detection signal or to expand the surface of the solid phase. For now, significant additions in performance can be achieved if we balance new ways of amplification with progressive improvements of existing procedures. For the future, new concepts derived form biosensors approach will lead to simultaneous multiple analysis on the same sample.

Biological Assay↗
PubMedDate not supplied

Detection of human papillomavirus types 6, 11, 16 and 18 in mucosal and cutaneous lesions by the multiplex polymerase chain reaction.

A multiplex polymerase chain reaction (PCR) based on the simultaneous amplification of human papillomavirus (HPV) types 6/11, 16 and 18 in a single-step procedure was developed, using primers chosen in the E6-E7 region. The specificity and sensitivity of this technique have been proved by amplifying mixtures or various amounts of plasmid-containing HPV DNA; it allowed the detection of as few as 5-25 HPV DNA copies. Application of the multiplex PCR to 71 clinical samples showed that HPV DNA was detected in 80% (45/57 cases) of mucosal biopsies and 35% (5/14 cases) of cutaneous specimens. HPV 16 was predominant in high-grade CIN whereas HPV 6 and 11 were detected more frequently in genital condylomas and laryngeal papillomas. In cutaneous Bowen's disease HPV 16, 18 or 6/11 + 16 were detected and in squamous cell carcinomas HPV 6/11 or 16 were found. After sequence amplification with primers of one HPV type, the clinical samples displayed the same HPV types but the frequency of positive and coinfected lesions increased. Thus, multiplex PCR is a valuable technique for typing HPV DNA but coinfections may be underestimated.

Adult↗