ABSTRACT
BACKGROUND AND OBJECTIVE: The purpose of this study was to test the hypothesis that the risk of silent aspiration is increased in non-invasive positive pressure ventilation. METHODS: We analysed the coordination between respiration and swallowing, in 12 young volunteers and 10 elder volunteers, by simultaneously monitoring respiratory flow, laryngeal movement and swallowing sound in three different conditions: control, continuous positive airway pressure (CPAP), and bi-level positive airway pressure (BiPAP). A step-wise multiple regression analysis was performed with the occurrence rate of inspiration after swallows as the dependent variable and various correlated variables as the independent variables. RESULTS: In both subject groups, the occurrence rate of inspiration after swallow was greater with BiPAP compared with control and CPAP conditions. Repetitive saliva swallowing test count and swallow non-inspiratory flow occurrence rate were extracted as predictor variables for risk of inspiration after swallows during BiPAP treatment. CONCLUSION: We found that the occurrence rate of inspiration after swallow is increased with BiPAP use irrespective of age. The results suggest that swallow non-inspiratory flow may trigger inspiratory support in the BiPAP mode, resulting in a risk of aspiration.
Subject(s)
Deglutition/physiology , Positive-Pressure Respiration , Respiratory Aspiration , Respiratory Physiological Phenomena , Adult , Aged , Female , Humans , Male , Positive-Pressure Respiration/adverse effects , Positive-Pressure Respiration/methods , Respiratory Aspiration/etiology , Respiratory Aspiration/physiopathology , Respiratory Aspiration/prevention & control , Risk Assessment/methods , Time Factors , VolunteersABSTRACT
PURPOSE: The effects of a carbon ion beam and X-rays on human pancreatic cancer stem-like cells were examined from the point of view of clonogenic survival and DNA repair. MATERIALS AND METHODS: Human pancreatic cancer stem-like cells were treated with and without carbon ion and X-ray irradiation, and then colony, spheroid and tumor formation assays as well as γH2AX foci formation assay were performed. RESULTS: The relative biological effectiveness (RBE) values of a carbon ion beam relative to X-ray for the MIA PaCa-2 and BxPc-3 cells at the D10 values were 1.85-2.10. The ability for colony, spheroid formation, and tumorigenicity from cancer stem-like CD44(+)/CD24(+) cells is significantly higher than that from non-cancer stem-like CD44(-)/CD24(-)cells. FACS data showed that CD44(+)/CD24(+) cells were more highly enriched after X-rays compared to carbon ion irradiation at isoeffective doses. The RBE values for the carbon ion beam relative to X-ray at the D10 levels for CD44(+)/CD24(+) cells were 2.0-2.19. The number of γH2AX foci in CD44(-)/CD24(-) cells was higher than that of CD44(+)/CD24(+) cells after irradiation with either X-ray or carbon ion beam. The number of γH2AX foci in CD44(+)/CD24(+) cells was almost the same in the early time, but it persists significantly longer in carbon ion beam irradiated cells compared to X-rays. CONCLUSIONS: Carbon ion beam has superior potential to kill pancreatic cancer stem cell-like cells, and prolonged induction of DNA damage might be one of the pivotal mechanisms of its high radiobiological effects compared to X-rays.
Subject(s)
DNA Repair/radiation effects , Heavy Ion Radiotherapy , Neoplastic Stem Cells/radiation effects , Pancreatic Neoplasms/pathology , X-Ray Therapy , Animals , CD24 Antigen/analysis , Cell Line, Tumor , Cell Survival/radiation effects , Histones/analysis , Humans , Hyaluronan Receptors/analysis , Pancreatic Neoplasms/radiotherapyABSTRACT
Although carbon ion therapy facilities are expensive, the biological effects of carbon ion beam treatment may be better against cancer (and cancer stem cells) than the effects of a photon beam. To investigate whether a carbon ion beam may have a biological advantage over X-rays by targeting cancer stem-like cells, human colon cancer cells were used in vitro and in vivo. The in vitro relative biological effectiveness (RBE) values of a carbon ion beam relative to X-rays at the D10 values were from 1.63 to 1.74. Cancer stem-like CD133(+), CD44(+)/ESA(+) cells had a greater ability for colony and spheroid formation, as well as in vivo tumorigenicity compared with the CD133(-), CD44(-)/ESA(-) cells. FACS (fluorescence-activated cell sorting) data showed that cancer stem-like cells were more highly enriched after irradiation with X-rays than carbon ion at doses that produced the same level of biological efficacy. A colony assay for cancer stem-like cells showed that RBE values calculated by the D10 levels were from 2.05 to 2.28 for the carbon ion beam relative to X-rays. The in vivo xenotransplant assay showed an RBE of 3.05 to 3.25, calculated from the slope of the dose-response curve for tumor growth suppression. Carbon ion irradiation with 15 Gy induced more severe xenograft tumor cell cavitation and fibrosis without significant enhancement of cells with putative cancer stem cell markers, CD133, ESA, and CD44, compared with 30 Gy X-rays, and marker positive cells were significantly decreased following 30 Gy carbon ion irradiation. Taken together, carbon ion beam therapy may have an advantage over photon beam therapy by improved targeting of putative colon cancer stem-like cells.
