No abstract

Regional variations and substrates of high-frequency rhythmic activity induced by cholinergic stimulation were studied in hippocampal slices with 64-electrode recording arrays. (1) Carbachol triggered ␤ waves (17.6 Ϯ 5.7 Hz) in pyramidal regions of 75% of the slices. (2) The waves had phase shifts across the cell body layers and were substantially larger in the apical dendrites than in cell body layers or basal dendrites. (3) Continuous, twodimensional current source density analyses indicated apical sinks associated with basal sources, lasting ϳ10 msec, followed by apical sources and basal sinks, lasting ϳ20 msec, in a repeating pattern with a period in the range of 15-25 Hz. (4) Carbachol-induced ␤ waves in the hippocampus were accompanied by 40 Hz (␥) oscillations in deep layers of the entorhinal cortex. (5) Cholinergically elicited ␤ and ␥ rhythms were eliminated by antagonists of either AMPA or GABA receptors. Benzodiazepines markedly enhanced ␤ activity and sometimes introduced a distinct ␥ frequency peak. (6) Twenty Hertz activity after orthodromic activation of field CA3 was distributed in the same manner as carbachol-induced ␤ waves and was generated by a current source in the apical dendrites of CA3. This source was eliminated by high concentrations of GABA A receptor blockers. It is concluded that cholinergically driven ␤ rhythms arise independently in hippocampal subfields from oscillatory circuits involving (1) bursts of pyramidal cell discharges, (2) activation of a subset of feedback interneurons that project apically, and (3) production of a GABA A -mediated hyperpolarization in the outer portions of the apical dendrites of pyramidal neurons.

No abstract

BackgroundsA potential strategy for the diagnosis of lung cancer is to exploit the distinct metabolic signature of this disease by way of biomarkers found in different sample types. In this study, we investigated whether specific volatile organic compounds (VOCs) could be detected in the culture medium of the lung cancer cell line A549 in addition to the urine of mice implanted with A549 cells.ResultsSeveral VOCs were found at significantly increased or decreased concentrations in the headspace of the A549 cell culture medium as compared with the culture medium of two normal lung cell lines. We also analyzed the urine of mice implanted with A549 cells and several VOCs were also found to be significantly increased or decreased relative to urine obtained from control mice. It was also revealed that seven VOCs were found at increased concentrations in both sample types. These compounds were found to be dimethyl succinate, 2-pentanone, phenol, 2-methylpyrazine, 2-hexanone, 2-butanone and acetophenone.ConclusionsBoth sample types produce distinct biomarker profiles, and VOCs have potential to distinguish between true- and false-positive screens for lung cancer.

Gastrointestinal (GI) motility is well organized. GI muscles act as a functional syncytium to achieve physiological functions under the control of neurones and pacemaker cells, which generate basal spontaneous pacemaker electrical activity. To date, it is unclear how spontaneous electrical activities are coupled, especially within a micrometre range. Here, using a microelectrode array, we show a spatio-temporal analysis of GI spontaneous electrical activity. The muscle preparations were isolated from guinea-pig stomach, and fixed in a chamber with an array of 8 × 8 planar multielectrodes (with 300 μm in interpolar distance). The electrical activities (field potentials) were simultaneously recorded through a multichannel amplifier system after high-pass filtering at 0.1 Hz. Dihydropyridine Ca 2+ channel antagonists are known to differentiate the electrical pacemaker activity of interstitial cells of Cajal (ICCs) by suppressing smooth muscle activity. In the presence of nifedipine, we observed spontaneous electrical activities that were well synchronized over the array area, but had a clear phase shift depending on the distance. The additional application of tetrodotoxin (TTX) had little effect on the properties of the electrical activity. Furthermore, by constructing field potential images, we visualized the synchronization of pacemaker electrical activities resolving phase shifts that were measurable over several hundred micrometres. The results imply a phase modulation mechanism other than neural activity, and we postulate that this mechanism enables smooth GI motility. In addition, some preparations clearly showed plasticity of the pacemaker phase shift.