No abstract

The prolonged effects of N-methyl-D-aspartate (NMDA) receptor activation on the proliferation and differentiation of hippocampal neural progenitor cells (NPCs) were studied. Under conditions of mitogen-mediated proliferation, a single NMDA pulse (5 μM) increased the fraction of 5-bromo-2-deoxyuridine (BrdU)-positive (BrdU+) cells after a delay of 72 hours. Similarly, a single systemic injection of NMDA (100 mg/kg) increased the number of BrdU+ cells in the dentate gyrus (DG) after 28 days, but not after 3 days. NMDA receptor activation induced an immediate influx of Ca2+ into the NPCs and the NPCs expressed and released vascular endothelial growth factor (VEGF) in an NMDA receptor-dependent manner within 72 hours. With repetitive stimulation at the same dose, NMDA stimulated the acquisition of a neuronal phenotype accompanied by an increase in the expression of proneural basic helix-loop-helix (bHLH) factors. Together these findings suggest that neurogenesis in the developing brain is likely to be both directly and indirectly regulated by complex interactions between Ca2+ influx and excitation-releasable cytokines, even at mild levels of excitation. In addition, our results are the first to show that stimulation of NPCs may lead to either proliferation or neuronal differentiation, depending on the level of NMDA receptor activation.

In this paper, we propose a modified Smith predictor with a new structure for unstable processes. The proposed new structure makes it possible to use the unstable model itself as a process model, while the previous modified Smith predictors provided no option to use a mismatched stable process model to guarantee stability. Accordingly, the proposed Smith predictor can predict the dynamics of the actual process much better than previous approaches. It also guarantees good robustness to modeling errors by separating servo and regulatory problems. Moreover, it demonstrates good disturbance rejection performances because the adjustable parameters of the PID controller for the regulatory problem are tuned systematically with an internal feedback loop.

SUMMARY Hunger is a powerful drive that stimulates food intake. Yet the mechanism that determines how the energy deficits that result in hunger are represented in the brain and promote feeding is not well understood. We previously described SLC5A11 – a sodium/solute co-transporter-like – (or cupcake) in Drosophila melanogaster, which is required for the fly to select a nutritive sugar over a sweeter nonnutritive sweetener after periods of food deprivation. SLC5A11 acts on approximately 12 pairs of ellipsoid body (EB) R4 neurons to trigger the selection of nutritive sugars, but the underlying mechanism is not understood. Here, we report that the excitability of SLC5A11-expressing EB R4 neurons increases dramatically during starvation and that this increase is abolished in the SLC5A11 mutation. Artificial activation of SLC5A11-expresssing neurons is sufficient to promote feeding and hunger-driven behaviors; silencing these neurons has the opposite effect. Notably, SLC5A11 transcript levels in the brain rose significantly when flies were starved, and dropped shortly after starved flies were refed. Furthermore, expression of SLC5A11 is sufficient for promoting hunger-driven behaviors and enhancing the excitability of SLC5A11-expressing neurons. SLC5A11 inhibits the function of Drosophila KCNQ potassium channel in a heterologous expression system. Accordingly, a knock-down of dKCNQ expression in SLC5A11-expressing neurons produces hunger-driven behaviors even in fed flies, mimicking the overexpression of SLC5A11. We propose that starvation increases SLC5A11 expression, which enhances the excitability of SLC5A11-expressing neurons by suppressing dKCNQ channels, thereby conferring the hunger state.

M atrix-disorganizing proteases, such as cathepsins or matrix metalloproteinases from macrophages, can destabilize atheromata, followed by plaque rupture to cause thromboembolic stroke or myocardial infarction. [1][2][3][4] We previously showed that molecular imaging of cathepsin-B (CatB) or matrix metalloproteinase-2/9 protease activity reflected the inflammatory component of atherosclerotic pathology in mice 5 and human atheromata. 6 We also showed that the protease imaging could quantitatively demonstrate plaque-stabilizing effects of antiatherosclerotic drugs 5 and exercise training 7 in mice. The principle of photodynamic therapy (PDT) is to kill unwanted cells by using a combination of photosensitizers and light illumination to generate highly reactive oxygen species that locally destroys cells over short diffusion distances.8-10 A recent PDT study using macrophage-targeted photosensitizers preliminarily demonstrated the viability of near-infrared lightactivated therapeutic nanoagents in the treatment of atherosclerotic vascular disease by showing preferential destruction of macrophages in vitro and in mouse atheromata. Objective-To investigate whether an intravenously injected cathepsin-B activatable theranostic agent (L-SR15) would be cleaved in and release a fluorescent agent (chlorin-e6) in mouse atheromata, allowing both the diagnostic visualization and therapeutic application of these fluorophores as photosensitizers during photodynamic therapy to attenuate plaquedestabilizing cathepsin-B activity by selectively eliminating macrophages. Approach and Results-Thirty-week-old apolipoprotein E knock-out mice (n=15) received intravenous injection of L-SR15 theranostic agent, control agent D-SR16, or saline 3× (D0, D7, D14). Twenty-four hours after each injection, the bilateral carotid arteries were exposed, and Cy5.5 near-infrared fluorescent imaging was performed. Fluorescent signal progressively accumulated in the atheromata of the L-SR15 group animals only, indicating that photosensitizers had been released from the theranostic agent and were accumulating in the plaque. After each imaging session, photodynamic therapy was applied with a continuous-wave diode-laser. Additional near-infrared fluorescent imaging at a longer wavelength (Cy7) with a cathepsin-B-sensing activatable molecular imaging agent showed attenuation of cathepsin-B-related signal in the L-SR15 group. Histological studies demonstrated that L-SR15-based photodynamic therapy decreased macrophage infiltration by inducing apoptosis without significantly affecting plaque size or smooth muscle cell numbers. Toxicity studies (n=24) showed that marked erythematous skin lesion was generated in C57/BL6 mice at 24 hours after intravenous injection of free chlorin-e6 and ultraviolet light irradiation; however, L-SR15 or saline did not cause cutaneous phototoxicity beyond that expected of ultraviolet irradiation alone, neither did we observe systemic toxicity or neurobehavioral changes. Conclusions-This is the first study showing that macrophage-se...