Calibration of second-order correlation functions for non-stationary sources with a multi-start multi-stop time-to-digital converter

A novel high-throughput second-order-correlation measurement system is developed which records and makes use of all the arrival times of photons detected at both start and stop detectors. This system is suitable particularly for a light source having a high photon flux and a long coherence time since it is more efficient than conventional methods by an amount equal to the product of the count rate and the correlation time of the light source. We have used this system in carefully investigating the dead time effects of detectors and photon counters on the second-order correlation function in the two-detector configuration. For a non-stationary light source, distortion of original signal was observed at high photon flux. A systematic way of calibrating the second-order correlation function has been devised by introducing a concept of an effective dead time of the entire measurement system.Comment: 7 pages, 6 figure

Reduction of Cav1.3 channels in dorsal hippocampus impairs the development of dentate gyrus newborn neurons and hippocampal-dependent memory tasks

Cav1.3 has been suggested to mediate hippocampal neurogenesis of adult mice and contribute to hippocampal-dependent learning and memory processes. However, the mechanism of Cav1.3 contribution in these processes is unclear. Here, roles of Cav1.3 of mouse dorsal hippocampus during newborn cell development were examined. We find that knockout (KO) of Cav1.3 resulted in the reduction of survival of newborn neurons at 28 days old after mitosis. The retroviral eGFP expression showed that both dendritic complexity and the number and length of mossy fiber bouton (MFB) filopodia of newborn neurons at 14 days old were significantly reduced in KO mice. Both contextual fear conditioning (CFC) and object-location recognition tasks were impaired in recent (1 day) memory test while passive avoidance task was impaired only in remote ( 20 days) memory in KO mice. Results using adeno-associated virus (AAV)-mediated Cav1.3 knock-down (KD) or retrovirus-mediated KD in dorsal hippocampal DG area showed that the recent memory of CFC was impaired in both KD mice but the remote memory was impaired only in AAV KD mice, suggesting that Cav1.3 of mature neurons play important roles in both recent and remote CFC memory while Cav1.3 in newborn neurons is selectively involved in the recent CFC memory process. Meanwhile, AAV KD of Cav1.3 in ventral hippocampal area has no effect on the recent CFC memory. In conclusion, the results suggest that Cav1.3 in newborn neurons of dorsal hippocampus is involved in the survival of newborn neurons while mediating developments of dendritic and axonal processes of newborn cells and plays a role in the memory process differentially depending on the stage of maturation and the type of learning task. © 2017 Kim et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

CD38-cADPR-SERCA Signaling Axis Determines Skeletal Muscle Contractile Force in Response to β-Adrenergic Stimulation

Background/Aims: Cyclic ADP-ribose (cADPR) is a Ca2+ -mobilization messenger that acts on ryanodine-sensitive Ca2+ channels in the sarcoplasmic reticulum (SR) Ca2+ stores. Moreover, it has been proposed that cADPR serves an additional role in activating the sarcoendoplasmic reticulum Ca2+ -ATPase (SERCA) pump. The aim of this study was to determine the exact mechanism by which cADPR regulates SR Ca2+ stores in physiologically relevant systems. Methods: We analyzed Ca2+ signals as well as the production of Ca2+ mobilizing messengers in the skeletal muscle cells of mice subjected to intensive exercise or in the SR fractions from skeletal muscle cells after β-adrenergic receptor (β-AR) stimulation. Results: We show that cADPR enhances SERCA activity in skeletal muscle cells in response to β-AR agonists, increasing SR Ca2+ uptake. We demonstrate that cADPR is generated by CD38, a cADPR-synthesizing enzyme, increasing muscle Ca2+ signals and contractile force during exercise. CD38 is upregulated by the cAMP response element–binding protein (CREB) transcription factor upon β-AR stimuli and exercise. CD38 knockout (KO) mice show defects in their exercise and cADPR synthesis capabilities, lacking a β-AR agonist-induced muscle contraction when compared to wild-type mice. The skeletal muscle of CD38 KO mice exhibits delayed cytosolic Ca2+ clearance and reduced SERCA activity upon exercise. Conclusion: These findings provide insight into the physiological adaptive mechanism by which the CD38- cADPR-SERCA signaling axis plays an essential role in muscle contraction under exercise, and define cADPR as an endogenous activator of SERCA in enhancing the SR Ca2+ load

Clinical Accuracy of Non-Contact Forehead Infrared Thermometer Measurement in Children: An Observational Study

We evaluated the clinical reliability and utility of temperature measurements using no-contact forehead infrared thermometers (NCFITs) by comparing their temperature measurements with those obtained using infrared tympanic thermometers (IRTTs) in children. In this observational, prospective, and cross-sectional study, we enrolled 255 children (aged 1 month to 18 years) from the pediatric surgery ward at a tertiary medical center in Korea. The mean age of the children was 9.05 ± 5.39 years, and 54.9% were boys. The incidence rate of fever, defined as an IRTT reading of ≥38.0 °C, was 15.7%. The ICC coefficient for the assessment of agreement between temperatures recorded by the NCFIT and IRTT was 0.87, and the κ-coefficient was 0.83. The bias and 95% limits of agreement were 0.15 °C (−0.43 to 0.73). For an accurate diagnosis of fever (≥38 °C), the false-negative rate was much lower, but the false-positive rate was higher, especially in 6-year-old children. Therefore, NCFITs can be used to screen children for fever. However, a secondary check is required using another thermometer when the child’s temperature is >38 °C. NCFITs are proposed for screening but not for measuring the temperature. For the latter, an accurate and reliable thermometer shall be used

Focusing of light energy inside a scattering medium by controlling the time-gated multiple light scattering

The efficient delivery of light energy is a prerequisite for the non-invasive imaging and stimulating of target objects embedded deep within a scattering medium. However, the injected waves experience random diffusion by multiple light scattering, and only a small fraction reaches the target object. Here, we present a method to counteract wave diffusion and to focus multiple-scattered waves at the deeply embedded target. To realize this, we experimentally inject light into the reflection eigenchannels of a specific flight time to preferably enhance the intensity of those multiple-scattered waves that have interacted with the target object. For targets that are too deep to be visible by optical imaging, we demonstrate a more than tenfold enhancement in light energy delivery in comparison with ordinary wave diffusion cases. This work will lay a foundation to enhance the working depth of imaging, sensing and light stimulation. © 2018 Macmillan Publishers Limited, part of Springer Nature. (c) All rights reserved

Reduction of Ca_v1.3 channels in dorsal hippocampus impairs the development of dentate gyrus newborn neurons and hippocampal-dependent memory tasks

<div><p>Ca_v1.3 has been suggested to mediate hippocampal neurogenesis of adult mice and contribute to hippocampal-dependent learning and memory processes. However, the mechanism of Ca_v1.3 contribution in these processes is unclear. Here, roles of Ca_v1.3 of mouse dorsal hippocampus during newborn cell development were examined. We find that knock-out (KO) of Ca_v1.3 resulted in the reduction of survival of newborn neurons at 28 days old after mitosis. The retroviral eGFP expression showed that both dendritic complexity and the number and length of mossy fiber bouton (MFB) filopodia of newborn neurons at ≥ 14 days old were significantly reduced in KO mice. Both contextual fear conditioning (CFC) and object-location recognition tasks were impaired in recent (1 day) memory test while passive avoidance task was impaired only in remote (≥ 20 days) memory in KO mice. Results using adeno-associated virus (AAV)-mediated Ca_v1.3 knock-down (KD) or retrovirus-mediated KD in dorsal hippocampal DG area showed that the recent memory of CFC was impaired in both KD mice but the remote memory was impaired only in AAV KD mice, suggesting that Ca_v1.3 of mature neurons play important roles in both recent and remote CFC memory while Ca_v1.3 in newborn neurons is selectively involved in the recent CFC memory process. Meanwhile, AAV KD of Ca_v1.3 in ventral hippocampal area has no effect on the recent CFC memory. In conclusion, the results suggest that Ca_v1.3 in newborn neurons of dorsal hippocampus is involved in the survival of newborn neurons while mediating developments of dendritic and axonal processes of newborn cells and plays a role in the memory process differentially depending on the stage of maturation and the type of learning task.</p></div

Effects of Ca_v1.3 KO on developments of dendrites, spines and MFB filopodia of DG newborn neurons.

<p>(A) Confocal images of GFP (+) neurons at 14 and 28 days after GFP-retroviral infection. <i>Scale bar</i>, 50 μm. (B-E) Quantification of dendritic development. *, **, *** indicate <i>p</i> < 0.05, <i>p</i> < 0.01, <i>p</i> < 0.001, respectively. (B) Total number of dendritic branching points at 14 and 28 days after viral infection. (Day 14, WT, 7.64 ± 0.41, n = 62, KO, 6.55 ± 0.25, n = 102, <i>p</i> = 0.017; Day 28, WT, 5.71 ± 0.20, n = 107, KO, 4.20 ± 0.18, n = 120, <i>p</i> < 0.00001, n = 3 animals per group). Two-way ANOVA, F_G = 26.96, <i>p</i> = 0.000; F_T = 73.08, <i>p</i> = 0.000; F_G+T = 0.68, <i>p</i> = 0.001. (C) Total dendritic length measurement at 14 and 28 days after viral injection. (Day 14, WT, 328.35 ± 14.57 μm, n = 69, KO, 362.34 ± 45.06 μm, n = 100, <i>p</i> = 0.12; Day 28, WT, 552.90 ± 19.15 μm, n = 107, KO, 466.34 ± 19.97 μm, n = 119, n = 4 animals per group, <i>p</i> = 0.002). Two-way ANOVA, F_G = 1.96, <i>p</i> = 0.162; F_T = 76.56, <i>p</i> = 0.000; F_G+T = 10.31, <i>p</i> = 0.001. (D-E) Number of dendritic crossings in Sholl analysis at 14 (D) and 28 days (E) after viral infection. (Day 28: 10 μm, WT, 1.29 ± 0.07, KO, 1.13 ± 0.04, <i>p</i> = 0.022; 20 μm, WT, 1.70 ± 0.10, KO, 1.39 ± 0.07, <i>p</i> = 0.011; 30 μm, WT, 2.30 ± 0.13, KO, 1.81 ± 0.09, <i>p</i> = 0.001; 40 μm, WT, 3.13 ± 0.16, KO, 2.44 ± 0.11, <i>p</i> = 0.001; 50 μm, WT, 3.69 ± 0.18, KO, 3.03 ± 0.13, <i>p</i> = 0.004; 60 μm, WT, 3.75 ± 0.18, KO, 3.15 ± 0.14, <i>p</i> = 0.010; 70 μm, WT, 3.73 ± 0.19, KO, 3.21 ± 0.15, <i>p</i> = 0.025; 80 μm, WT, 3.65 ± 0.16, KO, 2.98 ± 0.14, <i>p</i> = 0.005; 90 μm, WT, 3.49 ± 0.15, KO, 2.96 ± 0.15, <i>p</i> = 0.013; WT, n = 107 cells, KO, n = 122 cells, n = 4 animals per group). Two-way ANOVA, F_G = 10.54, <i>p</i> = 0.001; F_T = 27.18, <i>p</i> = 0.000; F_D = 92.87, <i>p</i> = 0.000; F_G+T = 34.97, <i>p</i> = 0.000; F_G+D = 1.23, <i>p</i> = 0.27; F_T+D = 23.76, <i>p</i> = 0.000; F_G+T+D = 0.92, <i>p</i> = 0.504. (F) <i>Left</i>, representative image (60x) of newborn neurons at 28 days after GFP-retroviral infection. Red, DAPI. White rectangle shows a distal dendritic region of a newborn neuron of Ca_v1.3 WT mice for spine analysis. <i>Right</i>, exemplary high magnification (60x/6x-zoom) images (<i>top</i>) and 3D reconstruction images (<i>bottom</i>) of a distal dendritic region of a newborn neuron of WT and Ca_v1.3 KO mice. White arrows indicate stubby spines, yellow arrows indicate mushroom spines and red arrows indicate thin spines. <i>Scale bar</i>, 50 μm (60x), 5 μm (60x/6x-zoom) and 2 μm (3D image). (G) Spine density plot for each type of spines. (Thin spines, WT, 0.82 ± 0.07 spines/μm, KO, 0.83 ± 0.06 spines/μm, <i>p</i> = 0.434; stubby spines, WT, 1.10 ± 0.07 spines/μm, KO, 0.95 ± 0.05 spines/μm, <i>p</i> = 0.064; mushroom spines, WT, 0.14 ± 0.017 spines/μm, KO, 0.20 ± 0.06 spines/μm, <i>p</i> = 0.409, WT, n = 28 cells, KO, n = 29 cells, n = 2 animals per group). (H) <i>Top</i>, confocal images of CA3 region axonal fibers of newborn neurons at 28 days after GFP expressing retrovirus injection. Red, DAPI. <i>Bottom</i>, high magnification images of axonal boutons near CA3 pyramidal cell layer. White and yellow arrows indicate boutons and filopodia, respectively. <i>Insets</i>, 3D image of bouton and filopodia. <i>Scale bars</i>, 50 μm (40x), 10 μm (40x/6x-zoom), 5 μm (<i>insets</i>). (I) Size of mossy fiber boutons (WT, 11.52 ± 0.47, n = 84 boutons; KO, 10.07 ± 0.45, n = 70 boutons, n = 3 animals per group, <i>p</i> = 0.029). (J) Total number of filopodia of axonal boutons (WT, 3.98 ± 0.25, n = 53 boutons, KO, 3.2 ± 0.19, n = 65 boutons, n = 3 animals per group, <i>p</i> = 0.010) and (K) the length of filopodia of axonal boutons (WT, 25.99 ± 2.02 μm, n = 53 boutons, KO, 19.16 ± 1.29 μm, n = 65 boutons, n = 3 animals per group, <i>p</i> = 0.004).</p

Expression of Ca_v1.3 in adult hippocampal area.

<p>(A) Ca_v1.3 expression in dorsal hippocampal area. Ca_v1.3 is shown in red and DAPI, a nuclear maker, is shown in blue. <i>Scale bars</i>, 200 μm (10x) and 50 μm (40x). (B) Images of developmental profiling of Ca_v1.3 expression in adult hippocampal newborn neurons. Confocal images of adult hippocampal newborn neurons, infected with GFP-retrovirus and stained with Ca_v1.3 antibody (red), were taken at 3, 7, 14 and 28 days after infection. White arrows indicate newborn cells infected with retrovirus. <i>Scale bars</i>, 50μm (40x) and 10 μm (40x/6x-zoom). (C) Ca_v1.3 antibody fluorescent intensity of newborn neurons (GFP (+), filled bar) and control mature neurons (GFP (-), open bar) of dorsal hippocampus shown at (B). A.U. indicates arbitrary unit. (Day 3, GFP(+), 658.10 ± 41.58, n = 9, GFP(-), 1302.51 ± 40.98, n = 50; Day 7, GFP(+), 558.19 ± 61.26, n = 9, GFP(-), 1149.03 ± 126.35, n = 50; Day 14, GFP(+), 950.79 ± 83.09, n = 7, GFP(-), 1264.75 ± 97.98, n = 50; Day 28, GFP(+), 1217.75 ± 55.34, n = 13, GFP(-), 1470.64 ± 115.84, n = 50; <i>p</i>(Day 3) < 0.000, <i>p</i>(Day 7) = 0.000, <i>p</i>(Day 14) = 0.035, <i>p</i>(Day 28) = 0.041). Two-way ANOVA, F_G = 66.17, <i>p</i> = 0.000; F_T = 15.22, <i>p</i> = 0.000; F_G+T = 3.20, <i>p</i> = 0.031. (D) Normalized Ca_v1.3 antibody fluorescent intensity of newborn neurons to that of mature neurons. (Day 3, 49.52 ± 3.61%, n = 9; Day 7, 48.26 ± 3.08%, n = 9; Day 14, 73.42 ± 5.94%, n = 7; Day 28, 83.76 ± 3.58%, n = 13; <i>p</i>(Day 3–7) = 0.795, <i>p</i>(Day 7–14) = 0.001, <i>p</i>(Day 14–28) = 0.138). One-way ANOVA, F = 20.913, <i>p</i> = 0.000. (E) Comparison of Ca_v1.3 expression among DG, CA1 and CA3 regions of dorsal hippocampus shown at (A) (each, n = 10). (DG, 1851.50 ± 54.44, n = 10; CA1, 2072.08 ± 38.63, n = 10; CA3, 2298.10 ± 115.40, n = 10; <i>p</i>(DG-CA1) = 0.004, <i>p</i>(CA1-CA3) = 0.080, <i>p</i>(DG-CA3) = 0.003). One-way ANOVA, F = 8.42, <i>p</i> = 0.001. *, **, *** indicate <i>p</i> < 0.05, <i>p</i> < 0.01, <i>p</i> < 0.001, respectively.</p