title: Effects of ultrasound on the structure and function of tumor necrosis factor-alpha.
abstract: The objective of this study was to investigate the effects of ultrasound on the structure and function of human tumor necrosis factor-alpha (TNF-alpha) and to study whether TNF-alpha underwent a denaturation process and the molecular structure was damaged when it was irradiated by ultrasound. The samples of TNF-alpha were dissolved in aqueous solution and filled into polystyrene tubes. High intensity ultrasound processor (20 kHz frequency, burst mode, 0.5 duty factor, 100-500 W total electrical power, 0-20 min total treatment time) was used during the treatment. The biologic activity of TNF-alpha was determined by its toxic activity towards TNF-alpha sensitive cell line L929 in the presence of actinomycin D. The methods of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) were used to detect the integrity of TNF-alpha molecule after it was irradiated by ultrasound. The results showed TNF-alpha could keep its biological activity, instead of undergoing a denaturation process, when it is irradiated by ultrasound in the aqueous solution; at the same time, the aggregates of TNF-alpha formed by the recombinant DNA E. coli could be dissociated through the molecular vibration induced by ultrasound energy. The biologic activity of TNF-alpha was not reduced, but small quantities of TNF-alpha molecular structure were damaged during the process of sonication. These features of TNF-alpha molecule irradiated by ultrasound probably gave TNF-alpha the advantage in being used in the drug microencapsulation and provided a new drugs formulation for tumor therapy.
authors.affiliation: Department of Biomedical Engineering, School of Life Science and Technology, Xi' an Jiaotong University, Xi' an, China.
authors.forename: Zhong-Min
authors.initials: ZM
authors.lastname: Tian
authors.forename: Ming-Xi
authors.initials: MX
authors.lastname: Wan
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.forename: Su-Pin
authors.initials: SP
authors.lastname: Wang
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Wu
authors.forename: Yu-Song
authors.initials: YS
authors.lastname: Ruan
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods; D002460:Cell Line; D003609:Dactinomycin / Q000494:pharmacology; D004355:Drug Stability; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D046911:Macromolecular Substances; D051379:Mice; D011489:Protein Denaturation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013329:Structure-Activity Relationship; D014409:Tumor Necrosis Factor-alpha / Q000737:chemistry* / Q000633:toxicity; D014465:Ultrasonics
chemical_list: D046911:Macromolecular Substances; D014409:Tumor Necrosis Factor-alpha; D003609:Dactinomycin