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.     

Immunomodulating effects of water-soluble extracts of traditional French Alps cheeses on a human T-lymphocyte cell line

The immunomodulation potential of four pressed-curd cheeses was studied in vitro on human T lymphocytes. T lymphocyte proliferation and metabolic activity were evaluated with optimized 5-bromo-2′-deoxyuridine and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assays, respectively. The up to 4.6-fold stimulation of T-lymphocyte proliferation and metabolic activity by Abondance and Tomme de Savoie water-soluble extracts (WSEs) at the lag phase suggested the presence of immunomodulating compounds in these cheeses. Since peptides released from milk proteins during cheesemaking are potential immunomodulatory compounds, the high-performance liquid chromatography peptide profiles of the cheese WSEs were determined. While no correlation between peptide composition and in vitro immunomodulation of T-lymphocyte cells could be established, peptide quantity, size and hydrophobicity were related to cheesemaking technological parameters such as cheese age and cooking temperature.     

In vitro study on digestion of peptides in Emmental cheese: analytical evaluation and influence on angiotensin I converting enzyme inhibitory peptides

A simple in vitro protocol simulating gastrointestinal digestion of proteins and peptides to investigate the effect of digestive enzymes on the biological activity of peptides present in dairy products was developed. This protocol consisted in a 30 min incubation with pepsin followed by a 4 h incubation with trypsin or pancreatin. It was applied to an Emmental cheese water-soluble extract (WSE) and to a casein solution (as a control). Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) allowed to monitor the digestion of proteins. Reversed-phase high-performance liquid chromatography (RP-HPLC) allowed to monitor the conversion of proteins and peptides into peptides and amino acids: it is proposed to use the mean retention time corresponding to the overall retention time distribution of molecules to assess the effect of digestive enzymes. The biological activity focused in this study was the angiotensin I converting enzyme (ACE) inhibitory activity. Digestion of Emmental WSE induced an increase of the ACE inhibition as compared to undigested WSE while a 10 kDa ultrafiltered WSE lost a part of its ACE inhibitory activity after digestion process. These results strongly suggest that digestive enzymes diminished the ACE inhibition by the peptides present in Emmental cheese WSE, while the digestion of peptides of high molecular weight would generate new ACE inhibitory peptides.     

Edible Antimicrobial Films Based on Chitosan Matrix

ABSTRACT: :
Edible chitosan coatings showed anti- Listeria monocytogenes effect evaluated by numeration and epifluorescence methods, imparting a strong localized functional effect at the food surface by active packaging. The use of film-forming solution in culture liquid medium showed a known flocculant phenomenon combined with bactericidal activity, keeping 20% of the initial microbial charge as viable cells in flocculant, which could develop subsequently. However, chitosan film showed 100% of L. monocytogenes inhibition for at least 8 d, completed by bactericidal activity measured by epifluorescence assays. A decrease in antibactericidal effect with time was obtained, most probably due to a decreasing availability of amino-groups of chitosan. Latter results were validated on Emmental cheese samples using L. innocua as model strain because of its nonpathogenicity.     

Chitosan Polymer as Bioactive Coating and Film against Aspergillus niger Contamination

ABSTRACT: The inhibitory activity of chitosan-based edible coatings and films was assessed against the Aspergillus niger food pathogen and deterioration microorganism. Spore-counting assays showed an almost total inhibition of A. niger growth when either film-forming solution or film were used at a low concentration of chitosan (0.1% w/v). Epifluorescence microscopic results showed the action of chitosan on the relative proportion of RNA compared with DNA. The water vapor permeability (WVP) of chitosan film was relatively low compared with the poor moisture barrier of some polysaccharide films. Moreover, a coating with chitosan film on an agar gel, used as a food model, induced a 30% reduction in water loss. These results showed potential applications of chitosan-based films as bioactive packaging with properties to limit the food dehydration phenomenon.