Biomedical subjects

C Desgranges

Publications and source records attributed to C Desgranges.

At least 73 records · Page 4Linked to original sources

PubMed1993

Comparison between direct binding, competition and agglutination assays in the characterization of polyclonal anti-idiotypes against anti-HBs human monoclonal antibodies.

Polyclonal anti-idiotypic antibodies to human monoclonal anti-HBs antibodies (MoAb1) were raised in rabbits and designated Ab2-H1 and Ab2-H2. These Ab2 were characterized using three assays. A direct binding ELISA evaluated specificity towards a panel of human monoclonal antibodies and gamma globulins. Competition radioimmunoassay (CRIA) revealed Ab2 specificities towards Ab1 antigen binding sites by inhibition of HBsAg/Ab1 binding. Ab2-H1 and Ab2-H2 had comparable reactivities in ELISA and CRIA, whereas, using affinity purified Ab2, a fast (10 min) agglutination test (Spherotest) revealed different Ab1/Ab2 binding properties. Ab2-H1 reacted in this Spherotest with the Ab1 against which it was known to be specific (Ab1-H1), whereas in the same assay Ab2-H2 showed no activity towards the variable regions of the Ab1 used for its production (Ab1-H2). When injected into rabbits Ab2-H1 induced anti-HBs Ab3 antibodies but Ab2-H2 did not, thereby confirming the assay results.

Agglutination Tests↗

PubMed1993

Expression of HTLV-I Env and Tax recombinant peptides in yeast: identification of immunogenic domains.

A peptide library of HTLV-I Env and Tax proteins was constructed in yeast in order to characterize which domains of these proteins are immunogenic in HTLV-I-infected individuals. Five yeast colonies (A to E) were selected using HTLV-I positive plasma, and one yeast colony (F) was selected using rabbit anti-Tax sera. Plasmid DNA present in each positive clone was recovered and sequenced. Overlapping clones A to E covered the C-terminal part of the gp46 exterior glycoprotein (aa 197 to 305) and were all glycosylated. Clone F encoded the C-terminal 25 aa of Tax (aa 329-353). Recombinant peptides were recognized by more than 40% of the HTLV-I positive human sera, confirming that they are major immunodominant domains. We studied the antibody response to each recombinant peptide in patients with TSP/HAM and asymptomatic carriers. Higher absorbance values were obtained with sera from TSP/HAM patients than from asymptomatic carriers, but the difference between the two groups was not statistically significant. Our study confirms that the COOH-terminal region of gp46 is highly immunogenic in HTLV-I-infected individuals and demonstrates a new immunogenic epitope of the Tax protein.

Amino Acid Sequence↗

PubMed1993

Biological risk factors for restenosis after percutaneous transluminal coronary angioplasty.

In an attempt to discern biological (such as thrombotic or fibrinolytic) risk factors in patients developing restenosis after percutaneous transluminal coronary angioplasty, the following factors were measured prior to angiography in a population of 23 patients (20 men, 3 women, mean age 57 +/- 5 yr) treated by a successful angioplasty (gain > 20% and residual stenosis < 50%) for stable angina pectoris and who had a routine angiographic restudy. The following factors were thus assessed: lipid factors: cholesterol, triglycerides, high density lipoprotein cholesterol, low density lipoprotein cholesterol, apolipoprotein AI, apolipoprotein B; coagulation factors: fibrinogen, antithrombin III, fibrinopeptide A, factor VIII coagulant, factor VIII antigen, protein C; factors of physiological fibrinolysis: plasminogen, alpha 2-antiplasmin, tissue plasminogen activator and euglobulin clot lysis time before and after venous occlusion, plasminogen activator inhibitor before venous occlusion; and factors of platelet release: beta-thromboglobulin, platelet factor 4. Also studied were clinical characteristics: age, gender, diabetes, hypertension, smoking habits, previous myocardial infarction; angiographic data: global extent of coronary artery disease, location of the stenosis in a bend or branch point, complexity of the lesion, initial and residual stenosis and treatment during follow-up. The coronary angiograms were analyzed by a computer-assisted method with automatic edge detection. On angiographic criteria, 6 patients (restenosis group) were judged to have developed a restenosis (30% decrease in diameter and/or return to a 50% stenosis). The other 17 patients (those without restenosis) were considered to have a persistent success. Apart from age (group without restenosis: 55 +/- 6; restenosis group 61 +/- 5, p < 0.04), there were no differences in clinical, angiographic or treatment variables. There were no differences in lipid factors, but significant differences were observed in hemostatic variables: fibrinogen (without restenosis: 3.18 +/- 0.83; restenosis: 3.83 +/- 0.51 milligrams, p = 0.05), tissue plasminogen activator before venous occlusion (without restenosis: 10.9 +/- 26.8; restenosis: 232.5 +/- 371.2 IU, p < 0.04), euglobulin clot lysis time after venous occlusion (without restenosis: 176.5 +/- 100.5; restenosis: 78.6 +/- 40.2 min, p < 0.05) and for marker of the platelet release: platelet factor 4 (without restenosis: 10.8 +/- 7.9; restenosis: 20.5 +/- 7.5 ng/l, p < 0.04). These findings indicate that patients developing restenosis after coronary angioplasty tend to have an imbalance in the prothrombotic-antithrombotic equilibrium prior to the procedure.

Aged↗

PubMed1993

Use of solid state fermentation to produce Beauveria bassiana for the biological control of European corn borer.

The production process of a new bioinsecticide against european corn borer is described. The entomopathogenic fungus, Beauveria bassiana, is cultivated by Solid State Fermentation (SSF). The culture support chosen, clay microgranules, humidified with optimal nutritive solution, is incubated in optimal conditions during 48 hours, then dried for 5 days. The bioinsecticide can be directly used after harvesting, without formulation. This process is original for several reasons : - The granulometry (500 microm) and the bulk density (0.6) of the microgranules are compatible with the mechanical standard application of pesticides on corn. - The bioinsecticide could be produced in a pilot reactor of 1600 1 capacity, on 0.5m-thick-layer.- The biomass bound to microgranules conserves its efficiency after storage for 12 months at 4 degrees C, unlike pure cells. - Like the chemical insecticides usually used, this bioproduct has a field efficiency of 80%. Moreover, the efficiency of the product persists during 3 weeks.

Journal Article↗

PubMed1993

Solid state fermentation reactors: from lab scale to pilot plant.

Relatively many workers in the world are studying different aspects in SSF processes but few are working on reactor design and scale-up. From about 10 years, we are developing reactors from lab scale to pilot plant, based on the same technology, reactor design and flowsheet to allow fermentation with a deep layer (up to 1 m in the pilot plant). These reactors have all a forced aeration and the possibility or not to agitate. Regulations of temperature and water content of the culture are monitored by a special device.

Journal Article↗

PubMed1993

Use of chitin measurement to estimate fungal biomass in solid state fermentation.

Twenty-two strains of twelve species of Deuteromycotina: Hyphomycetes were studied. Most of them had a variable glucosamine amount (standard deviation higher than 5%). However, if we consider that the amount of glucosamine is constant, the accuracy of the method remains satisfactory (10% instead of 5%, which is the accuracy of the chitin hydrolysis and colorimetric glucosamine measurement). So, by means of this measurement, the fungal growth kinetics could be followed on different solid media (vegetable material such as sugar beet pulp and sponge or mineral like clay granules) used. It is important to note that this method should not be used to compare different media without calibration.

Journal Article↗

PubMed1993

Membrane expression of HIV envelope glycoproteins triggers apoptosis in CD4 cells.

The cytopathic effect of HIV-1 and HIV-2 in CD4+ lymphocytes has been shown to be associated with apoptosis or programmed cell death. Using different experimental conditions, we demonstrate here that apoptosis is triggered by cell membrane expression of the mature HIV envelope glycoproteins, gp120-gp41 complex, and their interaction with CD4 receptor molecules. Viral entry alone did not induce apoptosis but virus replication was required in order to produce the gp120-gp41 complex. Indeed, expression of the HIV env gene alone in the CD4+ T cell line (CEM) was sufficient for the induction of apoptosis. In general, syncytium formation and apoptosis induction were closely associated as both events require functional envelope glycoproteins and CD4 molecules. Nevertheless, apoptosis but not syncytium formation was suppressed by a monoclonal antibody against CD4 that does not affect gp120 binding. Furthermore, single-cell killing by apoptosis was observed in infected cell cultures treated with a monoclonal antibody against gp41, which completely abolishes the formation of syncytia. These results indicate that apoptosis is not the consequence of toxic effects induced by the formation of syncytia but is triggered by the HIV envelope glycoproteins. Therefore, cell death during HIV infection in CD4+ lymphocyte cultures is due to a specific event triggered by the gp120-gp41 heterodimer complex programming death in metabolically active cells.

Amino Acid Sequence↗

PubMed1993

Production and characterization of a monoclonal antibody directed against HTLV-1 p19: use in a specific capture enzyme immunoassay.

An enzyme immunoassay (EIA) was developed for detection of Human T-cell Leukemia Virus antigen in culture supernatants and cell lysates. The assay used a mouse monoclonal antibody against HTLV-I p19 major core protein as capture antibody. It has a sensitivity of 1 microgram/ml of HTLV-I protein, 250 pg/ml of purified recombinant p19 and detected p19 in an 10(-2) diluted supernatant of MT2 infected cell and in a 100 MT2 cells lysate (10(6) cells taken at day 7 of culture). The assay enable us to discriminate between HTLV-I and HTLV-II antigens and is reproducibly negative for supernatants and cell lysates of uninfected cells and of HIV-1 infected cells. The assay was found to be more specific and 10 times more sensitive than the reverse transcriptase (RT) assay, and the EIA test became positive three days earlier than RT assay for the HTLV-I cell lines supernatants.

Animals↗

PubMed1993

Exogenous ATP induces a limited cell cycle progression of arterial smooth muscle cells.

Because exogenous ATP is suspected to influence the proliferative process, its effects on the cell cycle progression of arterial smooth muscle cells were studied by investigating changes in the mRNA steady-state level of cell cycle-dependent genes. Stimulation of cultured quiescent smooth muscle cells by exogenous ATP induced chronological activation not only of immediate-early but also of delayed-early cell cycle-dependent genes, which were usually expressed after a mitogenic stimulation. In contrast, ATP did not increase late G1 gene mRNA level, demonstrating that this nucleotide induces a limited cell cycle progression of arterial smooth muscle cells through the G1 phase but is not able by itself to induce crossing over the G1-S boundary and consequently DNA synthesis. An increase in c-fos mRNA level was also induced by ADP but not by AMP or adenosine. Moreover, 2-methylthioadenosine 5'-triphosphate but not alpha, beta-methyleneadenosine 5'-triphosphate mediated this kind of response. Taken together, these results demonstrate that extracellular ATP induces the limited progression of arterial smooth muscle cells through the G1 phase via its fixation on P2 gamma receptors.

Adenosine Triphosphate↗

PubMed1993

Osteopontin overexpression is associated with arterial smooth muscle cell proliferation in vitro.

To isolate the genes involved in the cell cycle G1 phase progression of arterial smooth muscle cells (SMCs), a cDNA clone (M11) was previously selected by differential hybridization screening of a mid-G1 serum-stimulated SMC cDNA library. The delay of induction after mitogenic stimulation, time of expression, and need for new protein synthesis for full expression made it possible to classify this gene in the "delayed early" gene group. Determination of the partial M11 cDNA sequence showed full homology with the osteopontin gene (secreted phosphoprotein 1, 2ar), an Arg-Gly-Asp-containing extracellular matrix protein. Osteopontin mRNA was also detected in the aorta at levels as high as in the kidney but lower than in bone, two tissues in which it has been previously detected. In vitro analysis of osteopontin expression in serum-stimulated quiescent SMCs and asynchronously cycling SMCs demonstrated that osteopontin overexpression was associated with SMC proliferation. In view of our results, the high osteopontin expression observed by others in the injured carotid artery could be explained by the involvement of SMCs in the proliferative process. Taken together, these results suggest that osteopontin may play an important role in pathological processes that are associated with arterial SMC proliferation, such as atherosclerosis or restenosis.

Animals↗

PubMed1992

Effects of angiotensins on cellular hypertrophy and c-fos expression in cultured arterial smooth muscle cells.

An increase in cell size and protein content was observed when quiescent arterial smooth muscle cells in culture were incubated with either angiotensin II or III. These effects were inhibited by the specific angiotensin type-1 receptor antagonist losartan (DuP753) but not by CGP42112A. In parallel, a transient and dose-dependent induction of c-fos was demonstrated not only with angiotensins II and III but also with angiotensin I. Both angiotensins II and III exerted their maximal effect at 1 microM, while angiotensin I needed a tenfold-higher concentration to exert an identical effect. As for hypertrophy, losartan also inhibits angiotensin-induced c-fos expression, suggesting that this gene may be involved into the hypertrophic process. Angiotensin-I-mediated c-fos induction is partially inhibited by the angiotensin-converting enzyme inhibitors captopril and trandolaprilate; given that an angiotensin-converting enzyme activity was detected in these smooth muscle cell cultures, these results suggest that angiotensin-I-induced c-fos expression is mediated in part via angiotensin-I conversion to angiotensin II, but also by other unidentified pathway(s). Angiotensin I could essentially induce smooth muscle cell hypertrophy by indirect mechanisms, while angiotensins II and III act directly on smooth muscle cells.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1992

Cell cycle dependent gene expression in quiescent stimulated and asynchronously cycling arterial smooth muscle cells in culture.

The expression of a set of cell cycle dependent (CCD) genes (c-fos, c-myc, ornithine decarboxylase (ODC), and thymidine kinase (TK)) was comparatively studied in cultured arterial smooth muscle cells (SMC) during exit from quiescence and exponential proliferation. These genes, which were not expressed in quiescent SMC, were chronologically induced after serum stimulation. c-fos mRNA were rapidly and transiently expressed very early in the G1 phase; c-myc and ODC peaked a few hours after serum stimulation and then remained at an intermediary level throughout the first cell cycle; TK mRNA and activity then appeared at the G1/S boundary and peak in G2/M phases. Except for c-fos, the other genes were also expressed in asynchronously cycling SMC (ACSMC); their expression was studied in elutriated subpopulations representative of cell cycle progression. c-fos mRNA were undetectable in any sorted subpopulations, even in the pure early G1 population. Despite a slight increase as the cell cycle advanced, c-myc and ODC genes were expressed throughout the ACSMC cell cycle. A faint TK activity was found in G1 subpopulations and increased in populations enriched in other phases; in contrast, TK mRNA remained highly expressed in all elutriated subpopulations. This study demonstrates significant modulations in CCD gene expression between quiescent stimulated and asynchronously cycling SMC in culture. This suggests that the events occurring during the emergence of SMC from quiescence are probably different from those in the G1 phase of ACSMC.

Cell Cycle↗

PubMed1992

Establishment of T-lymphoid cell lines from Morroccan patients with tropical spastic paraparesis.

Two T-cell lines were established from peripheral blood mononuclear cells of two Moroccan patients with tropical spastic paraparesis and then named PR52 and PR144. The two cell lines showed a T lineage of activated CD4+ with high density of Tac+ (IL2 receptor). No expression of CD8 was observed. The virus particles were detected by reverse transcriptase activity and the viral antigens were also detected by immunofluorescence (IF) and Western blot. After six months of culture greater than 90% of the cells exhibited HTLVI antigen by IF. Lysate virus particles on Western blot analysis revealed p19,p24, and p53 gag protein similar to those detected in C91/PL virus particles from an adult T-cell leukemia (ATL) patient. gp46 and gp61 were also weakly detected. These two T-cell lines established will serve as substrate for further comparative studies on TSP and ATL isolates.

Base Sequence↗

PubMed1992

Biological markers associated with prolonged survival in African children maternally infected by the human immunodeficiency virus type 1.

Sixteen children over the age of 5 years (Group 1) have been identified out of 537 children infected by human immunodeficiency virus and born to HIV-infected mothers, in Kigali, Rwanda. They were followed up for 2 years and compared with 16 younger AIDS patients (Group 2) and with 16 age- and gender-matched HIV-1 seronegative children (Group 3). Fourteen Group 1 subjects had anti-HIV-1 IgM which persisted during the entire study period, in 11 cases directed to HIV-1 envelope proteins. In vitro, immortalization of B lymphocytes by the Epstein-Barr virus confirmed a high production of IgM to envelope proteins. All these patients had anti-p 17 IgG which was not observed in 7 patients from Group 2. All 16 children mounted significant titers of neutralizing antibodies to HTLV-IIIB, and, in 8 patients tested, against two other HIV-1 strains, RII and MN. HIV-1-specific major histocompatibility complex (MHC)-restricted cytotoxic T cells were demonstrated in 3 of 5 of the subgroup who were tested. Prolonged survival over 5 years in children with maternally acquired HIV-1 infection is associated with a high titer of neutralizing antibodies, a persistent production of IGM to HIV-1 envelope proteins and of IgG to p 17.

Antibody-Dependent Cell Cytotoxicity↗

PubMed1992

In vitro HIV-1 entry and replication in Langerhans cells may clarify the HIV-1 genome detection by PCR in epidermis of seropositive patients.

Being dendritic antigen-presenting cells in skin and mucous membrane, Langerhans cells (LC) occur in areas at risk for inoculation by human immunodeficiency virus (HIV), and the question whether LC act as a target, reservoir, or vector for transmission of HIV has given rise to much controversy. To address this question, we first analyzed the epidermal compartment of skin from patients seropositive for HIV DNA. Second, we tested the susceptibility of each cell type normally found in this compartment to in vitro infection by HIV-1. A non-denatured DNA was obtained from epidermal sheets after a thermochemical treatment of biopsies (0.5 M ethylenediaminetetraacetic acid (EDTA), pH 7.5 at 60 degrees C for 90 seconds). Optimization of amplification of viral genome was performed with three primer pairs derived from gag, env, and pol sequences. Polymerase chain reaction (PCR) products were analyzed by Southern blot. Viral genome was found in five of 11 HIV-seropositive patients. To control the permissivity of epidermal cell population for HIV, cells isolated from the epidermal sheet of normal skin by trypsinization were co-cultured with HIV-1-carrying promonocytic cells (U937) and observed by electron microscopy. After 3-6 h of co-culture, numerous virions were either tightly bound or apparently engaged in the process of internalization through receptor-mediated endocytosis. At day 4 of co-culture, some infected LC appeared to release mature viral particles through bud formation. The in vitro HIV-1 entry and replication in LC may confirm the presence of the HIV-1 genome by PCR in epidermis of seropositive patients. The consequences of the permissivity of LC for HIV on the antigen-presenting function remain to be determined.

DNA, Viral↗

PubMed1992

Complement receptor type 2 mediates infection of the human CD4-negative Raji B-cell line with opsonized HIV.

Opsonization of the HTLV-RF and HTLV-IIIB strains of HIV-1 with normal human HIV seronegative serum under conditions that allow complement activation resulted in the productive infection of cells of the Raji B lymphoblastoid cell line. Under the same experimental conditions, no infection of Raji cells was observed with unopsonized virus. Infection of Raji cells with complement-opsonized HIV-1 was totally suppressed by preblocking the function of CR2 (the C3dg receptor, CD21) on the cells with a monoclonal anti-CR2 antibody cross-linked with rabbit F(ab')2 anti-mouse immunoglobulin antibodies. Infection of Raji cells occurred independently of CD4 since the cells lacked the expression of CD4 antigen and of CD4 transcripts. Thus, Raji cells may be infected with complement-opsonized HIV independently of CD4 and in the absence of antibodies. By mediating and/or enhancing HIV infection, complement and complement receptors contribute to extend the range of target cells to the virus and may increase infection in patients with a low viral load.

Acquired Immunodeficiency Syndrome↗

PubMed1992

A 2-year follow-up of an anti-HIV immune reaction in HIV-1 gp160-immunized healthy seronegative humans: evidence for persistent cell-mediated immunity.

The first trial of an anti-HIV immunization, using a recombinant vaccinia virus expressing gp160 (rV) for priming and paraformaldehyde-fixed rV-infected PBLs and soluble gp 160 for boosting, clearly showed an in vitro HIV-protective immune reaction. This result led us to carry out an additional 2 year Phase I clinical trial in 25 HIV-seronegative volunteers, using HIV gp 160 antigens for immunization in four different protocols. The 2 year trial showed (a) the safety of the preparations, (b) a transient humoral immunity following each boost, and (c) a long-lasting memory T-cell response. Memory cytotoxic T-lymphocytes (CTLs) induced by gp 160 antigen with or without vaccinia vector lysed HLA class I restricted target cells expressing HIV-1 env antigens. These results are consistent with CTLs being an effective component of an AIDS vaccine to control cell-to-cell viral replication, dissemination in the organism, and subsequent evolution toward AIDS.

AIDS Vaccines↗

PubMed1991

Complement mediates human immunodeficiency virus type 1 infection of a human T cell line in a CD4- and antibody-independent fashion.

Incubation of the human T cell lymphotropic virus (HTLV)-IIIB and HTLV-RF strains of human immunodeficiency virus type 1 (HIV-1) with normal seronegative human serum under conditions that allow complement activation resulted in enhancement of infection of the MT2 human T cell line cultured in the presence of low amounts of virus. Infection of MT2 cells was assessed by measuring reverse transcriptase activity in supernatants at day 9 of culture. Complement activation by viral suspensions occurred through the alternative pathway. Opsonization of HTLV-RF viral particles with complement was sufficient to allow a productive infection to occur in cells exposed to suboptimal amounts of virus. Infection of MT2 cells with suboptimal amounts of serum-opsonized HIV-1 was suppressed by blocking the C3dg receptor (CR2, CD21) on MT2 cells with monoclonal anti-CR2 antibody and rabbit F(ab')2 anti-mouse immunoglobulin antibodies. Blocking of the gp120-binding site on CD4 under similar experimental conditions had no inhibitory effect on infection of MT2 cells with opsonized virus. Opsonization of HIV-1 with seronegative serum also resulted in a CR2-mediated enhancement of the infection of normal peripheral blood mononuclear cells and T lymphocytes. These results indicate that complement in the absence of antibody may enhance infection of C3 receptor-bearing T cells with HIV-1, and that the interaction of opsonized virus with the CR2 receptor may result by itself in the infection of target T cells in a CD4- and antibody-independent fashion.

Acquired Immunodeficiency Syndrome↗