Identifying the Trends of Urinary microRNAs within Extracellular Vesicles for Esophageal Cancer.

Background: The advancement of multidisciplinary treatment has increased the need to develop tests to monitor tumor burden during treatment. We herein analyzed urinary microRNAs within extracellular vesicles from patients with esophageal squamous cell carcinoma (ESCC) and normal individuals using a microarray. Methods: Patients with advanced ESCC who underwent esophagectomy (A), endoscopic submucosal resection (ESD) (B), and healthy donors (C) were included. Based on microRNA expression among the groups (Analysis 1), microRNAs with significant differences between groups A and C were selected (Analysis 2). Of these candidates, microRNAs in which the change between A and C was consistent with the change between B and C were selected for downstream analysis (Analysis 3). Finally, microRNA expression was validated in patients with recurrence from A (exploratory analysis). Results: For analysis 1, 205 microRNAs were selected. For Analyses 2 and 3, the changes in 18 microRNAs were consistent with changes in tumor burden as determined by clinical imaging and pathological findings. The AUC for the detection of ESCC using 18 microRNAs was 0.72. In exploratory analysis, three of eighteen microRNAs exhibited a concordant trend with recurrence. Conclusions: The current study identified the urinary microRNAs which were significantly expressed in ESCC patients. Validation study is warranted to evaluate whether these microRNAs could reflect tumor burden during multidisciplinary treatment for ESCC.

Ex vivo cultured neuronal networks emit in vivo-like spontaneous activity.

Spontaneous neuronal activity is present in virtually all brain regions, but neither its function nor spatiotemporal patterns are fully understood. Ex vivo organotypic slice cultures may offer an opportunity to investigate some aspects of spontaneous activity, because they self-restore their networks that collapsed during slicing procedures. In hippocampal networks, we compared the levels and patterns of in vivo spontaneous activity to those in acute and cultured slices. We found that the firing rates and excitatory synaptic activity in the in vivo hippocampus are more similar to those in slice cultures compared to acute slices. The soft confidence-weighted algorithm, a machine learning technique without human bias, also revealed that hippocampal slice cultures resemble the in vivo hippocampus in terms of the overall tendency of the parameters of spontaneous activity.

Unbalanced excitability underlies offline reactivation of behaviorally activated neurons.

Hippocampal sharp waves (SWs)/ripples represent the reactivation of neurons involved in recently acquired memory and are crucial for memory consolidation. By labeling active cells with fluorescent protein under the control of an immediate-early gene promoter, we found that neurons that had been activated while mice explored a novel environment were preferentially reactivated during spontaneous SWs in hippocampal slices in vitro. During SWs, the reactivated neurons received strong excitatory synaptic inputs as opposed to a globally tuned network balance between excitation and inhibition.

Muscarinic receptor activation disrupts hippocampal sharp wave-ripples.

Cholinergic muscarinic innervations to the hippocampus play a role in learning and memory. Here we report that pharmacological activation of muscarinic receptors eliminates sharp wave-ripple events in the mouse hippocampal CA1 region in vivo and in vitro. This effect was associated with a decorrelation of excitatory synaptic inputs and a net increase in inhibitory conductances in pyramidal neurons. Multineuron calcium imaging revealed that muscarinic activation altered the spatiotemporal pattern of network activities. Thus, cholinergic input is likely to contribute to a neuromodulatory switch of hippocampal network states, as proposed in the "two-stage" model of learning processes.

High-speed multineuron calcium imaging using Nipkow-type confocal microscopy.

Conventional confocal and two-photon microscopy scan the field of view sequentially with single-point laser illumination. This raster-scanning method constrains video speeds to tens of frames per second, which are too slow to capture the temporal patterns of fast electrical events initiated by neurons. Nipkow-type spinning-disk confocal microscopy resolves this problem by the use of multiple laser beams. We describe experimental procedures for functional multineuron calcium imaging (fMCI) based on Nipkow-disk confocal microscopy, which enables us to monitor the activities of hundreds of neurons en masse at a cellular resolution at up to 2000 fps.

Asynchronously enhanced spiking activity of ischemic neuronal networks.

Cerebral ischemia causes the depletion of oxygen and nutrition from brain tissues, and when persistent, results in irreversible damage to the cell function and survival. The cellular response to ischemic conditions and its mechanisms have been investigated widely in in vivo and in vitro experimental models, yet no study has addressed the response of a whole neuronal network to energy deprivation with the single-cell resolution. Observations at the level of network are necessary, because the activity of individual neurons is nonlinearly integrated through a network and thereby gives rise to unexpectedly complex dynamics. Here we used functional multineuron calcium imaging (fMCI), an optical recording technique with high temporal and spatial resolution, to visualize the activity of neuron populations in hippocampus CA1 region under ischemia-like conditions ex vivo. We found that, although neurons responded to oxygen and glucose deprivation with an increase in the event frequency, they maintained an asynchronous network state. This is in contrast with other well known pathological states, in which the network hyperexcitability is usually accompanied by an increase in synchrony. We suggest that under ischemic conditions, at least to some time point, the neuronal network maintains the excitatory and inhibitory balance as a whole, whether actively or as a consequence of the cellular response to energy deprivation.

High-temperature, but not high-pressure, conditions alter neuronal activity.

We describe the effect of high pressure and high temperature on neuronal activity. Increased intracranial pressure is generally a pathological sign observed in intracerebral hemorrhage, brain edema, and brain tumor, yet little is known about how the hyperbaric pressure per se affects neuronal activity. Using a pressure/temperature-changeable perfusion chamber, we carried out functional multineuron calcium imaging to record spontaneous spiking activity simultaneously from about 100 neurons in hippocampal slice cultures. High-pressure conditions (up to 100 mmHg) did not alter the network excitability, whereas high-temperature conditions (up to 40 degrees C) increased synchronized network activity. Thus, neurons are sensitive to feverish conditions, but the acute hyperbaric circumstance itself is unlikely to exert a detrimental effect on neuronal function.