Biomedical subjects

C Lambré

Publications and source records attributed to C Lambré.

11 recordsLinked to original sources

PubMed1993

[The complement system].

After its discovery, about 100 years ago, complement was described as a cytotoxicity effector, the "armed hand" of antibodies. Since the description of an "alternate" pathway of activation, independent of antigen-antibody reactions, this restrictive concept has been modified. It has been progressively revealed to be a system that is composed of many proteins and our understanding of their biological roles has become much more developed. Nowadays, it is especially considered as a means for the body to generate peptides that regulate many functions: phagocytosis, antibody synthesis, inflammatory reactions, photosensitisation, coagulation, etc. Discovery of components, not only in the vehicles of serum or the other biological fluids but also associated with the cell membrane, has greatly increased the regions of action. Finally, progress in genetics, particularly in nucleic acid sequencing, has revealed families of proteins, a priori not apparent, that are analogues of the sequences and take part in the function of very varied areas. The roles of complement are thus not restricted only to immunological mechanisms, but they extend into many areas of biology and physiology.

Antigen-Antibody Reactions↗

PubMed1991

Sialidase in the guinea pig pulmonary parenchyma. Increased activity in the cytosolic and microsomal subcellular fractions after stimulation with Bacillus Calmette Guérin.

The sialidase activity was assayed in the guinea pig pulmonary parenchyma after removal of bronchoalveolar cells by washing. After differential centrifugation of the crude tissue homogenate, sialidase activities were measured in the subcellular fractions using the fluorogenic substrate 2-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminate. Sialidase activities were found in the lysosomal-enriched (17,000 x g pellet), in the microsomal (105,000 x g pellet) and in the cytosolic (105,000 x g supernatant) fractions. Microsomal and lysosomal forms of sialidase had an optimum activity at pH 3.6-3.8, whereas the optimum for the cytosolic form was pH 4.6. The activity of all three forms was inhibited by Cu2+, whereas 1 mM Zn2+ and 0.5 mM Ca2+ activated the lysosomal and the cytosolic forms, respectively. In the crude homogenate taken from lungs of Bacillus Calmette Guérin-(BCG-) stimulated guinea pigs, the sialidase activity was increased by 43% (p = 0.025) 3 weeks after the end of the treatment. The cytosolic (+246%) and microsomal (+51%) sialidase activities were significantly increased, whereas the lysosomal sialidase activity was not changed significantly by BCG stimulation.

Animals↗

PubMed1988

Identification of immunotoxic effects of chemicals and assessment of their relevance to man.

Immunotoxicity is defined as the adverse effects of foreign substances (xenobiotics) on the immune system. Two types of effects are possible: immunosuppression (which may result in an increased susceptibility to infection or to the development of tumours) and immunopotentiation (which may manifest as an allergy or as autoimmunity). There is, as yet, little evidence that well controlled occupational exposure to industrial chemicals has led to clinically significant immunosuppression. In contrast, a number of industrial chemicals have been shown to cause immunopotentiation in exposed populations, producing occupational asthma and contact dermatitis and possibly autoimmunity. In experimental models, immunosuppression (usually assessed by in vivo or in vitro immune function tests) has been induced by a wide range of chemicals but there are a few reports of the immunosuppression leading directly to an increased susceptibility to infection or to the development of tumours. Predictive experimental models are available for type IV allergic reactions, but the identification of chemicals that have a potential to cause other types of allergy or autoimmune reactions requires further research and the development and validation of new animal models. It is considered that routine subacute and chronic toxicity studies should include a full gross and histopathological assessment of the lymphoid organs to more accurately detect the potential of a chemical to cause immunotoxicity. Should such studies indicate that a substance has affected the immune system directly, an assessment of overall immune competence and function tests may be necessary using dose levels below those which cause frank toxicity. However, precise interpretation of immune function tests in terms of their relevance to human health requires an improved understanding of the extent of the functional reserve of the immune system. A strategy for assessing immunotoxicity in exposed human populations demonstrates a need for reliable clinical assessment, accurate medical record-keeping, an environmental and biological monitoring for levels of contaminating chemicals and the judicious use of well-validated immune function tests.

Animals↗

PubMed1976

[In vivo and in vitro effect of hyperbaric oxygen on lactate dehydrogenase activity of serum and organs of the mouse].

Lactate dehydrogenase activity in Mouse liver, kidney and lung was decreased after exposure to hyperbaric oxygen (1,8 atm) in vivo and in vitro. Oxygen inhibitory effect could occur through the oxidation of LDH essential free sulfhydryl groups. Serum LDH activity was diminished in vitro, while it was strongly increased in vivo. This enhancement probably resulted from the release in serum of cellular enzymes proceeding from oxygen injured tissues. Oxygen might inhibit both H and M LDH sub-units, since isozyme pattern was different in each organ.

Animals↗

PubMed1976