Amino acids metabolism by VO 208 hybridoma cells: some aspects of the culture process and medium composition influence.

In the present study an approach has been developed in order to examine the consequence of essential and non essential amino acid supplementation on VO208 hybridoma cells behaviour. The effect of amino acid enrichment has been studied taking into account the culture process, i.e., batch or continuous culture mode and the medium composition, i.e., a home made serum-free medium or a serum containing one. A group of 4 amino acids, i.e., Ser, Pro, Gly and Arg presented atypical evolution pattern of their extracellular concentration depending on the type of the medium and on the culture mode. Some amino acids were probably involved in the limitation of the cellular proliferation. Met was one of the amino acids that appears to may have been at limiting concentration in all cases. In continuous culture mode, an enrichment of amino acids resulted in a rapid improvement of the viable cell density in both media, with or without the presence of serum. For most amino acids, supplementation during continuous culture induced an increase of the amino acid uptake rate. A comparative analysis of amino acids utilisation, depending on the culture conditions studied in the present study, has been performed in order to propose an overall picture of amino acids metabolism by VO 208 Hybridoma cell line.

Ultrasonic methodology coupled to ATP bioluminescence for the non-invasive detection of fouling in food processing equipment--validation and application to a dairy factory.

The use of an ultrasonic apparatus (40 kHz) for the non-destructive, rapid and reproducible removal of biofilm from standard materials (stainless steel and polypropylene) in a dairy factory was investigated. The application of ultrasound with the tested conditions (10 s and 40 kHz) was found not to be detrimental for standard ATP (concentration ranging between 5 x 10(-9) and 10(-5) mol 1(-1)) and for prokaryotic cells, including both rods and coccoid-shaped bacteria (Escherichia coli and Staphylococcus aureus). It allowed the use of the ATP bioluminescence measurement for quantifying the biofilm removal. The repeatability of industrial milk removal was determined on fouled stainless steel and polypropylene sheets. The variability of the results with the sonication method was constant, +/-24% (coefficient of variation) for both surfaces, and was variable with the swabbing method, +/-42% for the stainless steel sheet and +/-74% for the polypropylene sheet. The ultrasonic apparatus removed twice the amount of industrial milk biofilm compared with the swabbing method in the case of the polypropylene sheets. The apparatus was used to validate the industrial cleaning protocols of a milk factory.

The development of an ultrasonic apparatus for the noninvasive and repeatable removal of fouling in food processing equipment.

A new ultrasonic apparatus operating at a frequency of 40 kHz was developed to dislodge biofilms from food processing equipment in order to assess the effectiveness of cleaning protocols. Sonication conditions to remove biofilms and quantification by ATP-bioluminescence are described. An industrial meat process was developed at the laboratory level to form a biofilm with industrial characteristics. Our results show that the biofilm removal by sonication during 10 s is reproducible and four times greater compared to the swabbing method (83% removal of fouling material against 20%). Unlike the swabbing method, this ultrasonic apparatus permitted the immediately demonstration of the inefficiency (within 1 min) of an industrial meat cleaning protocol. This apparatus is portable, easy to use and can be operated by unskilled users.

Feasibility studies of large scale production of human anti-tetanus toxoid monoclonal antibodies.

The feasibility of large scale production of human anti-tetanus toxoid monoclonal antibody for therapeutic use was evaluated using a human heterohybridoma. The effects of duration of subculture, transition from static to agitated culture conditions and the level of serum concentration were studied. The level of antibody secreted by the clone decreased with increasing length of subculture and decreasing serum concentration. The clone exhibited heterogeneity in expression of surface IgG after 2 or 7 weeks of subculture in static culture conditions irrespective of the serum concentration. However, a prolonged duration of subculture (9 weeks) in 3% serum medium had an effect on the expression of surface IgG both in static and agitated culture conditions. With respect to total (surface and intracellular) IgG, two distinct cell populations were observed. On long term subculture (9 weeks) in low serum medium (3% FCS), there was a decrease in the population which was the high synthesizer. In addition, when these cells were cultivated in agitated spinner flasks, a defect in secretion of antibodies was observed. Thus a general fall in the amount of antibody in the supernatant of agitated cultures was due to decrease in antibody synthesis as well as the defect in secretion of antibodies.