RESUMEN
The recent rapid increase in the prevalence of emerging tobacco- and nicotine-containing products, such as e-cigarettes, is being driven in part by their reduced-risk potential compared to tobacco smoking. In this study, we examined emission levels for selected cigarette smoke constituents, so-called "Hoffmann analytes", and in vitro toxicity of aerosol from a novel tobacco vapor product (NTV). The NTV thermally vaporizes a nicotine-free carrier liquid to form an aerosol which then passes through tobacco, where it absorbs tobacco-derived flavors and nicotine. The NTV results were compared with those for 3R4F cigarette smoke. Chemical analysis of the NTV aerosol demonstrated that Hoffmann analyte levels were substantially lower than in 3R4F smoke and that the most were below quantifiable levels. Results from in vitro bacterial reverse mutation, micronucleus and neutral red uptake assays showed that, in contrast with 3R4F smoke, the NTV aerosol failed to demonstrate any measurable genotoxicity or cytotoxicity. The temperature of tobacco during NTV use was measured at approximately 30 °C, which may explain the lower Hoffmann analyte emission and in vitro toxicity levels. These results suggest that the aerosol from the NTV has a very different toxicological profile when compared with combustible cigarette smoke.
Asunto(s)
Aerosoles/análisis , Productos de Tabaco/análisis , Animales , Células CHO , Línea Celular , Cricetulus , Sistemas Electrónicos de Liberación de Nicotina/métodos , Aromatizantes/química , Rojo Neutro/química , Nicotina/análisis , Humo/análisis , Fumar/efectos adversos , Nicotiana/químicaRESUMEN
Effects of auxin as plant hormones are widespread; in fact in almost all aspects of plant growth and development auxin plays a pivotal role. Although auxin is required for propagating cell division in plant cells, its effect upon cell division is least understood. If auxin is depleted from the culture medium, cultured cells cease to divide. It has been demonstrated in this context that the addition of auxin to auxin-starved nondividing tobacco BY-2 cells induced semisynchronous cell division. On the other hand, there are some cell lines, named habituated cells, that can grow without auxin. The cause and reason for the habituated cells have not been clarified. A habituated cell line named 2B-13 is derived from the tobacco BY-2 cell line, which has been most intensively studied among plant cell lines. When we tried to find the difference between two cell lines of BY-2 and 2B-13 cells, we found that the addition of culture filtrated from the auxin-habituated 2B-13 cells induced semisynchronous cell division in auxin-starved BY-2 cells. The cell division factor (CDF) that is responsible for inducing cell division in auxin-starved BY-2 cells was purified to near-homogeneity by sequential passage through a hydroxyapatite column, a ConA Sepharose column and a Sephadex gel filtration column. The resulting purified fraction appeared as a single band of high molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels by silver staining and was able to induce cell division in auxin-starved BY-2 cells. Identification of the protein by MALD-TOF-MS/MS revealed that it is structurally related to P-glycoprotein from Gossypioides kirkii, which belongs to ATP-binding cassette (ABC)-transporters. The significance of CDF as a possible ABC-transporter is discussed in relationship to auxin-autotrophic growth and auxin-signaling pathway.
Asunto(s)
Ácidos Indolacéticos/química , Nicotiana/citología , Nicotiana/fisiología , Proteínas de Plantas/química , Secuencia de Aminoácidos , División Celular , Células Cultivadas , Espectrometría de Masas , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , Péptido Hidrolasas , Proteínas de Plantas/aislamiento & purificaciónRESUMEN
In vitro biological studies on cigarette smoke have usually been made using either cigarette smoke condensate--obtained by trapping the particulate phase of smoke on a filter, or soluble smoke components--obtained by trapping cigarette smoke in buffer solution. However, these approaches may not truly reflect the physical and chemical condition of freshly generated smoke. Clearly it is important to be able to evaluate the biological effects of fresh smoke on mammalian cells for a better understanding of the potential effects of smoking. The CULTEX technology is a new experimental system for cultivation and exposure techniques enhanced the efficiency of in vitro studies, and allows direct exposure of cells intermittently at the air/liquid interface with ultrafine particles, gases, or mixtures of both which fixedly flows. The CULTEX technology has therefore been modified to evaluate the biological effects of whole cigarette smoke in an in vitro system. The exposure system design was based on a combination of the sedimentation procedure and the CULTEX cultivation technique. After freshly generated smoke was delivered onto cells, the flow was shut off and the medium was slowly removed. In this manner, cells were exposed to both the vapor and particulate phase of smoke efficiently. Cells were maintained in the liquid medium except during the exposure period to maintain the culture conditions and to protect the cells from both the influence of puff pressure and the airflow, which served to remove residual cigarette smoke. The medium was changed at every puff of smoke and so effectively eliminating the possibility of any effects caused by accumulation of soluble cigarette smoke components into the medium. This cycle was repeated and cells were exposed to freshly generated cigarette smoke intermittently.