OBJECTIVETo investigate the impact of the drug resistance on the radioresistance in human pancreatic cancer cell lines.

METHODSThree drug resistant pancreatic cancer cell sublines induced by fluorouracil (5-FU), adriamycin (ADM) and gemcitabine respectively, SW1990/FU, SW1990/ADM and SW1990/Gz, were tested for the cell cycle and radio-sensitivity with flow cytometry and clonogenic assay.

RESULTSCompared with SW1990, the cell cycle assay indicated higher G(0)/G(1) period percentage in SW1990/FU and SW1990/Gz, but the G(2)/M period percentage decreased; SW1990/FU had the same while SW1990/Gz had lower S period percentage. SW1990/ADM almost had a similar cell cycle with SW1990. Clonogenic assay showed both SW1990/FU and SW1990/Gz had greater survival fraction (SF(2)) than SW1990, but SW1990/ADM had seemingly similar SF(2) as SW1990.

CONCLUSIONDrug resistant pancreatic cancer cell lines have reduced G(2)/M period percentage and increased radioresistance.

Antineoplastic Agents ; pharmacology ; Cell Cycle ; drug effects ; Cell Line, Tumor ; Deoxycytidine ; analogs & derivatives ; pharmacology ; Doxorubicin ; pharmacology ; Drug Resistance, Neoplasm ; drug effects ; genetics ; Fluorouracil ; pharmacology ; Humans ; Pancreatic Neoplasms ; pathology ; Radiation Tolerance ; drug effects

Malocclusion is one of the three most common oral diseases reported by World Health Organization(WHO). In China, its incidence rate is rising. Malocclusion seriously affects the dental and maxillofacial function, facial appearance and growth development of nearly 260 million children in China, and what is more, it affects their physical and mental health development. Malocclusion occurrence is related to genetic and environmental factors. Early treatment of malocclusion can create a good dental and maxillofacial development environment, correct abnormal growth and control the adverse effects of abnormal genetic factors. It can effectively reduce the prevalence of children's malocclusion and enhance their physical and mental health. This is an urgent need from the economic perspective of our society, so it has great practical and social significance. Experts from the project group "standard diagnose and treatment protocols for early orthodontic intervention of malocclusions of children" which initiated by China National Health Institute of Hospital Administration wrote the "China Experts' Consensus on Preventive and Interceptive Orthodontic Treatments of Malocclusions of Children", which aims to guide and popularize the clinical practice, improve the clinical theory and practice level, and accelerate the disciplinary development of early treatment of children's malocclusion in China. The consensus elaborates the harmfulness of malocclusion and the necessity of early treatment, and brings up the principles and fundamental contents. Based on the law of dental and maxillofacial development, this paper puts forward the guiding suggestions of preventive and interceptive treatments in different stages of dental development ranging from fetus to early permanent dentition. It is a systematic project to promote and standardize the early treatment of malocclusion. Through scientific and comprehensive stratified clinical practice and professional training, the clinical system of early treatment of malocclusion in China will eventually be perfected, so as to comprehensively care for children's dental and maxillofacial health, and improve their oral and physical health in China.
Child ; China/epidemiology* ; Consensus ; Dental Care ; Humans ; Malocclusion/prevention & control* ; Orthodontics, Interceptive