Analysing the eosinophil cationic protein - a clue to the function of the eosinophil granulocyte

Eosinophil granulocytes reside in respiratory mucosa including lungs, in the gastro-intestinal tract, and in lymphocyte associated organs, the thymus, lymph nodes and the spleen. In parasitic infections, atopic diseases such as atopic dermatitis and asthma, the numbers of the circulating eosinophils are frequently elevated. In conditions such as Hypereosinophilic Syndrome (HES) circulating eosinophil levels are even further raised. Although, eosinophils were identified more than hundred years ago, their roles in homeostasis and in disease still remain unclear. The most prominent feature of the eosinophils are their large secondary granules, each containing four basic proteins, the best known being the eosinophil cationic protein (ECP). This protein has been developed as a marker for eosinophilic disease and quantified in biological fluids including serum, bronchoalveolar lavage and nasal secretions. Elevated ECP levels are found in T helper lymphocyte type 2 (atopic) diseases such as allergic asthma and allergic rhinitis but also occasionally in other diseases such as bacterial sinusitis. ECP is a ribonuclease which has been attributed with cytotoxic, neurotoxic, fibrosis promoting and immune-regulatory functions. ECP regulates mucosal and immune cells and may directly act against helminth, bacterial and viral infections. The levels of ECP measured in disease in combination with the catalogue of known functions of the protein and its polymorphisms presented here will build a foundation for further speculations of the role of ECP, and ultimately the role of the eosinophil

Influence of chemical agents on interactions in dairy products: Effect of SDS on casein micelles

International audienceThe addition of SDS during skim milk reconstitution is an original approach to study the effect of an ionic amphiphilic molecule on the milk system and particularly on the casein micelle component. SDS-induced changes in casein micelles were investigated by turbidimetry, rheology, scanning electron microscopy (SEM) and biochemical measurements (including soluble proteins analysis). This study shows that casein micelles were able to interact together to form micellar aggregates or milk gel without coagulating agents addition, when milk was reconstituted in the presence of SDS. This micellar aggregation, depending on the SDS concentration, is confirmed by SEM observations showing that the general aspect of casein micelles was affected by SDS treatment. Biochemical analysis indicated that SDS induced micellar casein dissociation. SDS-induced milk gel formation required a defined level of casein dissociation which could be also related to a particular micellar state

Effect of Temperature of Milk Acidification on Rennet Gel Properties

International audienceChanges in mineral solubilization and rennet reaction rate were investigated after decreasing milk pH to 6.3 by lactic acid addition at a temperature of acidification (TAC) of 25 or 35 ЊC with a short period of equilibration. With increasing TAC, casein micelles retained higher amounts of Ca and P, and at a given temperature of coagulation, rennet clotting time was increased, and dGЈ/dt decreased. This effect was confirmed by the microstructure of casein micelles during the first stage of the enzymic coagulation indicating that the aggregation of para-kcasein was observed later at higher TAC. The effect of TAC on rennet milk gel formation could be attributed to the nature of the micellar mineral content and the conformational state of casein micelles before rennet action

Identification of Interactions Among Casein Gels Using Dissociating Chemical Agents

International audienceTo evaluate the nature of the main interactions that are involved in the formation of casein gels made by the acidification or rennet coagulation of milk, we investigated the combined effects of ultracentrifugation and specific dissociating agents on protein solubilization. The method used was based on the ability of gelled proteins to resist the dissociating action of solutions of urea, sodium dodecyl sulfate, or EDTA. Results showed that hydrophobic interactions and calcium bonds were the most important forces involved in the rennet milk gel matrix; hydrophobic, hydrogen, and electrostatic interactions were homogeneously distributed in the gel formed from acidified milk