Stand development and regeneration during a 33-year period in a seral Picea glehnii forest, northern Japan

The original publication is available at www.springerlink.comArticleECOLOGICAL RESEARCH. 21(1):35-42(2006)journal articl

Hypocretin/Orexin Peptides Alter Spike Encoding by Serotonergic Dorsal Raphe Neurons through Two Distinct Mechanisms That Increase the Late Afterhyperpolarization

Orexins (hypocretins) are neuropeptides that regulate multiple homeostatic processes, including reward and arousal, in part by exciting serotonergic dorsal raphe neurons, the major source of forebrain serotonin. Here, using mouse brain slices, we found that, instead of simply depolarizing these neurons, orexin-A altered the spike encoding process by increasing the postspike afterhyperpolarization (AHP) via two distinct mechanisms. This orexin-enhanced AHP (oeAHP) was mediated by both OX1 and OX2 receptors, required Ca(2+) influx, reversed near EK, and decayed with two components, the faster of which resulted from enhanced SK channel activation, whereas the slower component decayed like a slow AHP (sAHP), but was not blocked by UCL2077, an antagonist of sAHPs in some neurons. Intracellular phospholipase C inhibition (U73122) blocked the entire oeAHP, but neither component was sensitive to PKC inhibition or altered PKA signaling, unlike classical sAHPs. The enhanced SK current did not depend on IP3-mediated Ca(2+) release but resulted from A-current inhibition and the resultant spike broadening, which increased Ca(2+) influx and Ca(2+)-induced-Ca(2+) release, whereas the slower component was insensitive to these factors. Functionally, the oeAHP slowed and stabilized orexin-induced firing compared with firing produced by a virtual orexin conductance lacking the oeAHP. The oeAHP also reduced steady-state firing rate and firing fidelity in response to stimulation, without affecting the initial rate or fidelity. Collectively, these findings reveal a new orexin action in serotonergic raphe neurons and suggest that, when orexin is released during arousal and reward, it enhances the spike encoding of phasic over tonic inputs, such as those related to sensory, motor, and reward events. SIGNIFICANCE STATEMENT: Orexin peptides are known to excite neurons via slow postsynaptic depolarizations. Here we elucidate a significant new orexin action that increases and prolongs the postspike afterhyperpolarization (AHP) in 5-HT dorsal raphe neurons and other arousal-system neurons. Our mechanistic studies establish involvement of two distinct Ca(2+)-dependent AHP currents dependent on phospholipase C signaling but independent of IP3 or PKC. Our functional studies establish that this action preserves responsiveness to phasic inputs while attenuating responsiveness to tonic inputs. Thus, our findings bring new insight into the actions of an important neuropeptide and indicate that, in addition to producing excitation, orexins can tune postsynaptic excitability to better encode the phasic sensory, motor, and reward signals expected during aroused states

Differential Actions of Orexin Receptors in Brainstem Cholinergic and Monoaminergic Neurons Revealed by Receptor Knockouts: Implications for Orexinergic Signaling in Arousal and Narcolepsy

Orexin neuropeptides influence multiple homeostatic functions and play an essential role in the expression of normal sleep-wake behavior. While their two known receptors (OX1 and OX2) are targets for novel pharmacotherapeutics, the actions mediated by each receptor remain largely unexplored. Using brain slices from mice constitutively lacking either receptor, we used whole-cell and Ca(2+) imaging methods to delineate the cellular actions of each receptor within cholinergic [laterodorsal tegmental nucleus (LDT)] and monoaminergic [dorsal raphe (DR) and locus coeruleus (LC)] brainstem nuclei-where orexins promote arousal and suppress REM sleep. In slices from OX(-/-) 2 mice, orexin-A (300 nM) elicited wild-type responses in LDT, DR, and LC neurons consisting of a depolarizing current and augmented voltage-dependent Ca(2+) transients. In slices from OX(-/-) 1 mice, the depolarizing current was absent in LDT and LC neurons and was attenuated in DR neurons, although Ca(2+)-transients were still augmented. Since orexin-A produced neither of these actions in slices lacking both receptors, our findings suggest that orexin-mediated depolarization is mediated by both receptors in DR, but is exclusively mediated by OX1 in LDT and LC neurons, even though OX2 is present and OX2 mRNA appears elevated in brainstems from OX(-/-) 1 mice. Considering published behavioral data, these findings support a model in which orexin-mediated excitation of mesopontine cholinergic and monoaminergic neurons contributes little to stabilizing spontaneous waking and sleep bouts, but functions in context-dependent arousal and helps restrict muscle atonia to REM sleep. The augmented Ca(2+) transients produced by both receptors appeared mediated by influx via L-type Ca(2+) channels, which is often linked to transcriptional signaling. This could provide an adaptive signal to compensate for receptor loss or prolonged antagonism and may contribute to the reduced severity of narcolepsy in single receptor knockout mice

Orexin Receptor Activation Generates Gamma Band Input to Cholinergic and Serotonergic Arousal System Neurons and Drives an Intrinsic Ca(2+)-Dependent Resonance in LDT and PPT Cholinergic Neurons

A hallmark of the waking state is a shift in EEG power to higher frequencies with epochs of synchronized intracortical gamma activity (30-60 Hz) - a process associated with high-level cognitive functions. The ascending arousal system, including cholinergic laterodorsal (LDT) and pedunculopontine (PPT) tegmental neurons and serotonergic dorsal raphe (DR) neurons, promotes this state. Recently, this system has been proposed as a gamma wave generator, in part, because some neurons produce high-threshold, Ca(2+)-dependent oscillations at gamma frequencies. However, it is not known whether arousal-related inputs to these neurons generate such oscillations, or whether such oscillations are ever transmitted to neuronal targets. Since key arousal input arises from hypothalamic orexin (hypocretin) neurons, we investigated whether the unusually noisy, depolarizing orexin current could provide significant gamma input to cholinergic and serotonergic neurons, and whether such input could drive Ca(2+)-dependent oscillations. Whole-cell recordings in brain slices were obtained from mice expressing Cre-induced fluorescence in cholinergic LDT and PPT, and serotonergic DR neurons. After first quantifying reporter expression accuracy in cholinergic and serotonergic neurons, we found that the orexin current produced significant high frequency, including gamma, input to both cholinergic and serotonergic neurons. Then, by using a dynamic clamp, we found that adding a noisy orexin conductance to cholinergic neurons induced a Ca(2+)-dependent resonance that peaked in the theta and alpha frequency range (4-14 Hz) and extended up to 100 Hz. We propose that this orexin current noise and the Ca(2+) dependent resonance work synergistically to boost the encoding of high-frequency synaptic inputs into action potentials and to help ensure cholinergic neurons fire during EEG activation. This activity could reinforce thalamocortical states supporting arousal, REM sleep, and intracortical gamma

Magneto-optical Imaging Using Polarization Modulation Method

A magneto-optical (MO) microscope that uses the polarization modulation method has been developed for quantitative MO imaging. In this technique, images of MO rotation and ellipticity are reconstructed from three images for different polarization states; i.e., linear, right-circular, and left-circular polarization states. The three polarization states are generated either by rotating a quarter-wave plate or by changing the voltage applied to a liquid crystal modulator (LCM). Measurements are performed using a patterned thin film of Bi,Ga-substituted yttrium iron garnet prepared on a glass substrate. The values of MO rotation and ellipticity obtained from the images for several wavelengths between 450 and 650 nm are found to agree quantitatively with those obtained by an MO spectrometer. Hysteresis loops at any point of the image can be displayed by simply placing a pointer at the position. A real-time MO imaging with a rate of 1 frame/s is also achieved by using the LCM and a high-speed charge-coupled device camera

ビョウインマエ シンパイ テイシ ニオケル キュウキュウ キュウメイシ ノ キカン ソウカン ニツイテ : ホンケン ノ ゲンジョウ ト コンゴ ノ カダイ

Activities of Japanese Paramedics have increased and advanced year by year. Especially, intubation for OHCPA（out of hospital cardiopulmonary arrest） is approved since July 2004, but it is necessary to finish the training in Fire-fighter’s school and intubation practice in hospitals. In Fire-fighter’s school, Paramedics attend lectures and simulation, and in hospital, intubation practice for patients. Medical-control is the system for keeping the qualities and verification of details in the scene of pre-hospital medical care. This report discusses the states and problems of paramedic intubation, practice in hospital, airway management, from the questionnaire survey

Compact hyperbolic universe and singularities

Recently many people have discussed the possibility that the universe is hyperbolic and was in an inflationary phase in the early stage. Under these assumptions, it is shown that the universe cannot have compact hyperbolic time-slices. Though the universal covering space of the universe has a past Cauchy horizon and can be extended analytically beyond it, the extended region has densely many points which correspond to singularities of the compact universe. The result is essentially attributed to the ergodicity of the geodesic flow on a compact negatively curved manifold. Validity of the result is also discussed in the case of inhomogeneous universe. Relationship with the strong cosmic censorship conjecture is also discussed.Comment: 8 pages with 7 figure

The effects inhibiting the proliferation of cancer cells by far-infrared radiation (FIR) are controlled by the basal expression level of heat shock protein (HSP) 70A

We developed a tissue culture incubator that can continuously irradiate cells with far-infrared radiation (FIR) of wavelengths between 4 and 20 μm with a peak of 7–12 μm, and found that FIR caused different inhibiting effects to five human cancer cell lines, namely A431 (vulva), HSC3 (tongue), Sa3 (gingiva), A549 (lung), and MCF7 (breast). Then, in order to make clear the control system for the effect of FIR, the gene expression concerned to the inhibition effect by FIR were analyzed. In consequence, basal expression level of HSP70A mRNA was higher in A431 and MCF7 cells than in the FIR-sensitive HSC3, Sa3, and A549 cells. Also, the over expression of HSP70 inhibited FIR-induced growth arrest in HSC3 cells, and an HSP70 siRNA inhibited the proliferation of A431 cells by irradiation with FIR. These results indicate that the effect of a body temperature range of FIR suppressing the proliferation of some cancer cells is controlled by the basal expression level of heat shock protein (HSP) 70A. This finding suggested that FIR should be very effective medical treatment for some cancer cells which have a low level of HSP70. Still more, if the level of HSP70 in any cancer of a patient was measured, the effect of medical treatment by FIR can be foreseen for the cancer