Electronic Resonant Stimulated Raman Scattering Micro-Spectroscopy

Recently we have reported electronic pre-resonance stimulated Raman scattering (epr-SRS) microscopy as a powerful technique for super-multiplex imaging (Wei, L.; Nature 2017, 544, 465−470). However, under rigorous electronic resonance, background signal, which mainly originates from pump–probe process, overwhelms the desired vibrational signature of the chromophores. Here we demonstrate electronic resonant stimulated Raman scattering (er-SRS) microspectroscopy and imaging through suppression of electronic background and subsequent retrieval of vibrational peaks. We observed a change of the vibrational band shapes from normal Lorentzian, through dispersive shapes, to inverted Lorentzian as the electronic resonance was approached, in agreement with theoretical prediction. In addition, resonant Raman cross sections have been determined after power-dependence study as well as Raman excitation profile calculation. As large as 10^(–23) cm^2 of resonance Raman cross section is estimated in er-SRS, which is about 100 times higher than previously reported in epr-SRS. These results of er-SRS microspectroscopy pave the way for the single-molecule Raman detection and ultrasensitive biological imaging

Electronic Resonant Stimulated Raman Scattering Micro-Spectroscopy

Recently we have reported electronic pre-resonance stimulated Raman scattering (epr-SRS) microscopy as a powerful technique for super-multiplex imaging (Wei, L.; Nature 2017, 544, 465−470). However, under rigorous electronic resonance, background signal, which mainly originates from pump–probe process, overwhelms the desired vibrational signature of the chromophores. Here we demonstrate electronic resonant stimulated Raman scattering (er-SRS) microspectroscopy and imaging through suppression of electronic background and subsequent retrieval of vibrational peaks. We observed a change of the vibrational band shapes from normal Lorentzian, through dispersive shapes, to inverted Lorentzian as the electronic resonance was approached, in agreement with theoretical prediction. In addition, resonant Raman cross sections have been determined after power-dependence study as well as Raman excitation profile calculation. As large as 10^(–23) cm^2 of resonance Raman cross section is estimated in er-SRS, which is about 100 times higher than previously reported in epr-SRS. These results of er-SRS microspectroscopy pave the way for the single-molecule Raman detection and ultrasensitive biological imaging

Two-color vibrational imaging of glucose metabolism using stimulated Raman scattering

A two-color vibrational imaging technique for simultaneously mapping glucose uptake and incorporation activity inside single living cells is reported. Heterogeneous patterns of glucose metabolism are directly visualized from the ratiometric two-color images for various cell types, cells undergoing epithelia-to-mesenchymal transitions and live mouse brain tissues. The two-color imaging of glucose metabolism here demonstrates the development of multi-functional vibrational probes for multicolor imaging of cellular metabolism

PET Imaging of Neuroinflammation in Alzheimer's Disease

Neuroinflammation play an important role in Alzheimer's disease pathogenesis. Advances in molecular imaging using positron emission tomography have provided insights into the time course of neuroinflammation and its relation with Alzheimer's disease central pathologies in patients and in animal disease models. Recent single-cell sequencing and transcriptomics indicate dynamic disease-associated microglia and astrocyte profiles in Alzheimer's disease. Mitochondrial 18-kDa translocator protein is the most widely investigated target for neuroinflammation imaging. New generation of translocator protein tracers with improved performance have been developed and evaluated along with tau and amyloid imaging for assessing the disease progression in Alzheimer's disease continuum. Given that translocator protein is not exclusively expressed in glia, alternative targets are under rapid development, such as monoamine oxidase B, matrix metalloproteinases, colony-stimulating factor 1 receptor, imidazoline-2 binding sites, cyclooxygenase, cannabinoid-2 receptor, purinergic P2X7 receptor, P2Y12 receptor, the fractalkine receptor, triggering receptor expressed on myeloid cells 2, and receptor for advanced glycation end products. Promising targets should demonstrate a higher specificity for cellular locations with exclusive expression in microglia or astrocyte and activation status (pro- or anti-inflammatory) with highly specific ligand to enable in vivo brain imaging. In this review, we summarised recent advances in the development of neuroinflammation imaging tracers and provided an outlook for promising targets in the future

Optimized Main Ditch Water Control for Agriculture in Northern Huaihe River Plain, Anhui Province, China, Using MODFLOW Groundwater Table Simulations

Controlled drainage by regulating the groundwater level in open ditches is necessary to ensure the normal growth of crops in Northern Huaihe River Plain, China. The groundwater model MODFLOW was calibrated and validated in a representative area, and was then conducted to simulate the groundwater under different main drainage ditch water depth control schemes during the growth period of corn and wheat. Then the scenario with highest water depth (Scenario 20) from 1989 to 2019 was simulated, and the annual cumulative drought and waterlogging intensity (ACDWI) were analyzed in each decade and in different hydrological years. The results showed that the study area was dominated by drought stress. The lowest level of drought stress was achieved under Scenario 20. The frequency of drought gradually decreased from north to south in the study area. Moreover, the ACDWI decreased with increase of precipitation during 1989 to 2019. The results indicated that it was important to store water during the dry season, while it is also necessary to control the drainage in the rainy season to drain excess water on time. The results suggested that the water depth of the main drainage ditch should be regulated by zoning and by season to alleviate crop drought and waterlogging

BAM15 attenuates transportation-induced apoptosis in iPS-differentiated retinal tissue

Abstract Background BAM15 is a novel mitochondrial protonophore uncoupler capable of protecting mammals from acute renal ischemic-reperfusion injury and cold-induced microtubule damage. The purpose of our study was to investigate the effect of BAM15 on apoptosis during 5-day transportation of human-induced pluripotent stem (hiPS)-differentiated retinal tissue. Methods Retinal tissues of 30 days and 60 days were transported with or without BAM15 for 5 days in the laboratory or by real express. Immunofluorescence staining of apoptosis marker cleaved caspase3, proliferation marker Ki67, and neural axon marker NEFL was performed. And expression of apoptotic-related factors p53, NFkappaB, and TNF-a was detected by real-time PCR. Also, location of ganglion cells, photoreceptor cells, amacrine cells, and precursors of neuronal cell types in retinal tissue was stained by immunofluorescence after transportation. Furthermore, cell viability was assessed by CCK8 assay. Results Results showed transportation remarkably intensified expression of apoptotic factor cleaved caspase3, p53, NFkappaB, and TNF-a, which could be reduced by supplement of BAM15. In addition, neurons were severely injured after transportation, with axons manifesting disrupted and tortuous by staining NEFL. And the addition of BAM15 in transportation was able to protect neuronal structure and increase cell viability without affecting subtypes cells location of retinal tissue. Conclusions BAM15 might be used as a protective reagent on apoptosis during transporting retinal tissues, holding great potential in research and clinical applications