Effect of storage temperature on the keeping quality of commercially pasteurized milk

Pour étudier l'effet de la température sur la durée de conservation du lait pasteurisé, du lait fraîchemf:'nt pasteurisé et non homogénéisé provenant de deux laiteries industrielles, a été conservé à 7 et à 25°C. L'évolution du pH, des caractéristiques sensorielles, et de la flore totale du lait a été étudiée durant la période de conservation. L'altération du lait dont le taux microbien initial était de 10 3 UFC/ml a été observée entre le 5 ème et 6ème jour de conservation à 7°C. A 25°C, cette durée n'a été que de 20 à 24 heures. Au début de l'altération, le taux microbien a dépassé 10 7 UFC/ml. Les deux laits ont montré les mêmes signes d'altération à savoir la putréfaction, l'amertume, le caractère fruité, et la rancidité à 7°C; tandis qu'à 25°C, les défauts détectés étaient l'acidité, le surissement, et la rancidité. Les échantillons de lait ont montré également le signe de coagulation après ébullition, 2 heures avant l'altération à 25°C alors qu'à 7°C la coagulation du lait a eu lieu le même jour du début de l'altération. To study the effect of temperature on the shelf-life, freshly pasteurized and unhomogenized whole milk from two dairy plants was stored at 7 and 25°C. Microbial, sensory, and pH changes were monitored during storage. Milk of 1000 CFU/ml, as initial microbial count, showed evidence of spoilage between 5th and 6th day of storage at 7°C. When stored at 25°C, the shelf-life was only 20 to 24 hours. The microbial count at the time of spoilage exceeded 10000000 CFU/ml. Both brands ofmilk showed similar spoilage characteristics of putrid, bitter, fruity and rancid at 7°C and acid, sour, and rancid defects at 25°C. Milk samples showed clotting on boiling 2 hours before evidence of spoilage at 25°C and simultaneously with spoilage at 7°C

Photobiomodulation of human fibroblasts and keratinocytes with blue light: Implications in wound healing

In recent years, photobiomodulation (PBM) has been recognized as a physical therapy in wound management. Despite several published research papers, the mechanism underlying photobiomodulation is still not completely understood. The investigation about application of blue light to improve wound healing is a relatively new research area. Tests in selected patients evidenced a stimulation of the healing process in superficial and chronic wounds treated with a blue LED light emitting at 420 nm; a study in animal model pointed out a faster healing process in superficial wound, with an important role of fibroblasts and myofibroblasts. Here, we present a study aiming at evidencing the effects of blue light on the proliferation and metabolism in fibroblasts from healthy skin and keratinocytes. Different light doses (3.43, 6.87, 13.7, 20.6, 30.9 and 41.2 J/cm2) were used to treat the cells, evidencing inhibitory and stimulatory effects following a biphasic dose behavior. Electrophysiology was used to investigate the effects on membrane currents: healthy fibroblasts and keratinocytes showed no significant differences between treated and not treated cells. Raman spectroscopy revealed the mitochondrial Cytochrome C (Cyt C) oxidase dependence on blue light irradiation: a significant decrease in peak intensity of healthy fibroblast was evidenced, while it is less pronounced in keratinocytes. In conclusion, we observed that the blue LED light can be used to modulate metabolism and proliferation of human fibroblasts, and the effects in wound healing are particularly evident when studying the fibroblasts and keratinocytes co-cultures

Ready-to-use protein G-conjugated gold nanorods for biosensing and biomedical applications

Abstract Background Gold nanorods (GNRs) display unique capacity to absorb and scatter near infrared light, which arises from their peculiar composition of surface plasmon resonances. For this reason, GNRs have become an innovative material of great hope in nanomedicine, in particular for imaging and therapy of cancer, as well as in photonic sensing of biological agents and toxic compounds for e.g. biomedical diagnostics, forensic analysis and environmental monitoring. As the use of GNRs is becoming more and more popular, in all these contexts, there is emerging a latent need for simple and versatile protocols for their modification with targeting units that may convey high specificity for any analyte of interest of an end-user. Results We introduce protein G-coated GNRs as a versatile solution for the oriented immobilization of antibodies in a single step of mixing. We assess this strategy against more standard covalent binding of antibodies, in terms of biocompatibility and efficiency of molecular recognition in buffer, serum and plasma, in the context of the development of a direct immunoenzymatic assay. In both cases, we estimate an average of around 30 events of molecular recognition per particle. In addition, we disclose a convenient protocol to store these particles for months in a freezer, without any detrimental effect. Conclusions The biocompatibility and efficiency of molecular recognition is similar in either case of GNRs that are modified with antibodies by covalent binding or oriented immobilization through protein G. However, protein G-coated GNRs are most attractive for an end-user, owing to their unique versatility and ease of bioconjugation with antibodies of her/his choice