Lung C-fiber CNS reflex: role in the respiratory consequences of extended environmental tobacco smoke exposure in young guinea pigs.

Environmental tobacco smoke (ETS) exposure harms the respiratory health of children and is associated with an increased risk of asthma and sudden infant death syndrome (SIDS). The mechanisms by which ETS causes these effects are not understood. We hypothesized that one mechanism is an upregulation of the lung C-fiber central nervous system (CNS) reflex responses, which would result in exaggerated reflex responses of apnea, bronchoconstriction, and mucous hypersecretion. The purpose of this work is to highlight evidence obtained in an animal model of postnatal ETS exposure supporting the hypothesis and present data suggesting that actions of the neuropeptide substance P in the nucleus tractus solitarius (NTS) may contribute. Exposing young guinea pigs to sidestream smoke, the surrogate for ETS, for 5 weeks during the equivalent of human childhood, increased the excitability of afferent lung C fibers and NTS neurons in the CNS reflex pathway and prolonged the expiratory apnea. The findings suggest that an increased excitability of NTS neurons that can augment reflex output may contribute to respiratory symptoms in children exposed to ETS. Besides ETS exposure, substance P can also excite NTS neurons and augment lung C-fiber CNS reflex responses. Others have shown that substance P synthesis in lung C fibers is upregulated by another environmental stimulant, allergen. Thus, an upregulation of the substance P system at NTS synapses could contribute to the increased NTS excitability and enhanced reflex responses to lung C-fiber stimulation, providing a potential mechanism to help explain the association of ETS exposure with respiratory symptoms and SIDS

Status Report of LNS Accelerator Complex in 2002(IV. Status Report of LNS Accelerator Complex in 2002)

Operation status of an electron accelerator complex at Laboratory of Nuclear Science, Tohoku University is reported. After a completion of a new building containing an experimental vault, the inspection for the radiation safety was done in the beginning of October, 2003, so that most of user machine time was consumed in the latter half of the fiscal year 2002

Status Report of LNS Accelerator Complex in 2001(IV. Status Report of LNS Accelerator Complex in 2001)

The electron accelerator complex at the Laboratory of Nuclear Science, Tohoku University has been operated for various fields of science. A 35-year-old 300 MeV electron linac is still working well. However troubles due to aging is rapidly getting serious. In addition, because of multi-purpose use of the linac many different beam characteristics are requested by the users, so that the operation mode has been complicate. In this report, the operation status of the accelerator complex including major troubles experienced in the fiscal year 2001 is described and future plan is shortly discussed by showing the present machine operation