Biomedical subjects

M Guenounou

Publications and source records attributed to M Guenounou.

77 records · Page 5Linked to original sources

PubMedDate not supplied

Immunological activities of RU-41740, a glycoproteic extract from Klebsiella pneumoniae. II.--Activation of macrophage cytotoxicity against tumour cells and production of a cytotoxic factor.

RU-41740, a glycoprotein extract from Klebsiella pneumoniae, is an immunomodulating agent with a broad spectrum of activities. It enhances several macrophage functions, including interleukin-1 (IL-1) secretion. Present data show that RU-41740 was able to promote murine macrophage cytotoxicity against tumour cells. A soluble cytotoxic factor (CF) was found in supernatants from macrophage cultures stimulated with RU-41740. These supernatants were shown to contain IL-1. CF was detected on L-929 cells sensitized by actinomycin D. CF was analysed on the basis of MW and pHi: after gel filtration on "Ultrogel Aca54", a single peak of CF was found in the range of 50-60 Kd and was then distinct from IL-1, which was eluted at 15 Kd. After chromatofocusing, CF was found in a narrow peak of pH 4.8. CF was detected in supernatants 2 h after macrophage stimulation by RU-41740, and its release was abolished by pretreatment of macrophages with cycloheximide (2 micrograms/ml). CF described here shares several properties with tumour necrosis factor (TNF).

Animals↗

PubMedDate not supplied

Study of adjuvant and mitogenic activities of bacterial peptidoglycans with different structures.

The adjuvant and mitogenic properties of bacterial peptidoglycans (PG) of different structures have been compared. The PG from Bacillus megaterium and Staphylococcus aureus were adjuvant-active in the guinea-pig, and mitogenic for guinea-pig and mouse lymphocytes. On the other hand the PG from Micrococcus lysodeikticus and Corynebacterium poinsettiae exerted neither adjuvant nor mitogenic activities. Mitogenic PG were selective B mitogens. They were mitogenic for splenocytes from Nude mice and inactive towards T-cell-enriched populations. They were mitogenic in both germ-free mice and in the C3H/HeJ strain which is unresponsive to lipopolysaccharide.

Adjuvants, Immunologic↗

PubMedDate not supplied

[Rapid determination of the synergy of clavulanic acid and beta lactams by measuring the intracellular ATP by bioluminescence].

Twenty clinical isolates of ampicillin- and carbenicillin-resistant or susceptible (two strains) Gram-negative rods, producing at least one beta-lactamase, were examined for susceptibility to a combination of ampicillin or carbenicillin with clavulanic acid (enzymatic inhibitor). Synergy was evaluated by the reduction of the beta-lactam agar dilution MIC and by the measurement of intracellular AYP using firefly bioluminescence. The potentiation effect of clavulanic acid was variable, depending on resistance levels, species and types of beta-lactamase (TEM, SHV-1, CARB, OXA, MAL and Cpase). The synergy was significant, with 10 mg/l of inhibitor for all the strains producing TEM-1, TEM-2 and Carb-2 except for one strain of Serratia marcescens (TEM-2). The synergy was weak for Levinea strains (Citrobacter diversus biotype b), biosynthesizing specific penicillinases as MAL-1. No potentiation effect was observed for strains producing a cephalosporinase, such as Escherichia coli and Pseudomonas aeruginosa. This effect appeared to be variable for strains producing the oxacillin-hydrolysing enzyme (OXA-1), such as E. coli and P. aeruginosa. A positive correlation was clearly demonstrated between the MIC values and the intracellular ATP concentration in bacteria within 2 h. The opportunity of using the firefly assay for the rapid determination of synergy between beta-lactam antibiotics and clavulanic acid is discussed.

Adenosine Triphosphate↗

PubMedDate not supplied

Immunomodulation by cytokine antisense oligonucleotides.

The cytokine network is involved in normal immune reaction and in the progression of several pathologies. Antisense (AS) oligonucleotides, which allow specific inhibition of expression of proteins, offer a new methodology to investigate this complex network. This review focuses on the use of AS to modulate cytokine expression. AS may act in different ways such as blocking fixation or progression of the ribosome along the mRNA, mRNA cleavage by RNase H, or preventing normal RNA maturation. In order to improve AS efficiency, chemical modifications have been developed, and improvement of oligonucleotide uptake has been achieved with different systems of vectorization including liposomes (neutral, cationic, immunoliposome), nanoparticles, or covalent attachment of a carrier. In oncogenesis, intracellular or extracellular autocrine loops have been demonstrated by the use of cytokine AS. Involvement of cytokines in immunological reactions (TH1 and TH2 subset, IgE response, lymphokine activated killer, cytotoxic T lymphocyte...) and in hematopoiesis have also been studied with this approach. Therapeutic application of AS has been suggested by inhibition of inflammatory cytokines in vivo. Clinical trials using AS are under investigation in virological and in oncological diseases. At present, cytokine antisenses primarily represent a tool for dissecting the function of a cytokine in vitro, but they may offer in the future a new way for immunomodulation intervention.

Adjuvants, Immunologic↗

PubMedDate not supplied

[Cytokines and allergic response].

Allergic reactions are under the control of several events that occur sequentially following allergen exposure, recognition by the immune system, IgE production and their interaction with effector cells bearing Fc epsilon receptors. The lymphocyte activation in response to allergens determines the intensity and the nature of the immune response. Cytokines produced by T (and non-T) cells are involved in the polarized development of the specific immune response. In particular, type 1 and type 2 cytokines are responsible for the control of the different steps during allergic reactions. Th2 cytokines and particularly IL4 are responsible for switching the immunoglobulin synthesis by B cells to IgE production. They also play a key role in the activation of effector cells that occurs following allergen interaction with fixed specific IgE and participate to the local inflammatory reaction. Cytokine profile determination appears to represent a helpful laboratory parameter in the understanding of the mechanisms underlying allergic diseases. The development of new technological tools may allow the use of cell activation parameters, and cytokine profiles determination in clinical biology. This review aims to analyze the involvement of the cytokine network in the mechanisms leading to IgE production and the involvement of cytokines in effector mechanisms of allergic reactions. It also analyses the potential use of cytokine profile determination for diagnosis purpose and survey of immune desensitization of allergic diseases.

Animals↗