Development of a quantitative assay for residual host cell proteins in a recombinant subunit vaccine against human respiratory syncytial virus.

We have developed and validated a process-specific immunoligand assay based on the Threshold system for the quantification of residual host cell proteins (HCPs) in a recombinant subunit vaccine candidate against the human respiratory syncytial virus (hRSV). The industrial process of this vaccine produced in Escherichia coli, involved five chromatography steps for the production of clinical-grade batches. The clearance of non-product-related protein throughout the purification process was documented by the evaluation of the HCP content in the chromatographic fractions at each step of the downstream processing. The assay had a detection limit of 0.5 ng/ml of HCP equivalent to 10 parts per million (ppm). The quantification limit was 1.3 ng/ml of HCP, giving a sensitivity range of the assay of 10 to 30 ppm. To our knowledge, this is the first sensitive HCP assay reported for a vaccine.

Platelet releasate treatment improves skin healing in diabetic rats through endogenous growth factor secretion.

Although impaired skin wound healing in diabetes is a well established phenomenon, virtually nothing is known of its underlying mechanism. We have demonstrated that diabetic skin exhibited a significant deficiency in total mitogenic activity, notably a diminution in FGF1, FGF2 and TGFbeta-like molecules. We postulated that impaired skin healing could be explained by a decreased expression of endogenous growth factors that could be compensated by a platelet releasate (PR) added in situ. Histological studies showed that PR treatment improved tissue repair and restored disturbed healing steps observed in untreated diabetic rat skin although reepithelialization was not altered. Our data demonstrate that PR treatment induces important modulations of the quantity and the kinetic of secretion of endogenous growth factors in the wounds. Although exogenous factors present in PR could no longer be quantified in the wounds after 3 days, our results indicated that factors contained in PR may have: 1) a direct and immediate effect on the growth of neodermal cells, combined to 2) a long term stimulation of endogenous growth factor synthesis in situ during cutaneous wound healing in diabetic rats.

Blood compatibility of silicone rubber chemically coated with cross-linked albumin.

A new method is reported for chemically coating cross-linked albumin onto silicone rubber in an attempt to improve the blood compatibility of the material. Promising results were obtained in an evaluation using both vena cava and renal embolus antithrombogenicity tests ondogs. Coated silicone rubber rings induced much less renal emboli than uncoated ones after one week implantation.

Magnetic enzyme membranes as active elements of electrochemical sensors. Lactose, saccharose, maltose bienzyme electrodes.

The direct monitoring of sugars such as lactose, maltose, saccharose is not only useful at the applied point of view but also at the fundamental point of view for studying enzymology, especially in microbiology and fermentation. Benzyme systems were extensively used in solution for analytical applications in industry and medicine. The progress in the field of immobilization of bienzyme systems [1-3], especially within membranes [4-5], makes possible the production of new analytical devices. From the studies dealing with concentration profiles in artificial enzyme membranes [14], evidence was obtained for a well defined relationship between the local concentration of a metabolite and concentration of the first substrate in the bulk solution. In the described systems a substrate is transformed into glucose within a membrane, the glucose is then transformed in gluconic acid with a local oxygen consumption. The local pO2 level is linked to the glucose oxidase velocity, which is only linked to the glucose production, that is to say to the concentration of the first substrate. The enzyme electrode is based on the transformation of kinetic phenomena (reaction rates) into absolute values (local concentrations) through the diffusion-reaction coupling process. The manufacture of magnetic enzyme electrodes [6] allows convenient use of the active sensors. The pO2 electrode has some adventages, namely the specificity based on the selectivity of the gas permeable membrane and the linear relationship between the oxygen and the output of the electrode. pCO2, pH, ion electrodes give a logarithmic response as a function of the concentration. The grafting of a multienzyme system on a sensor allows a study of sequential systems in a defined context with a measurement of the local concentration of the metabolites. The tool is useful for both kinetics [4] and regulation studies [5].