Soft-in-Rigid Strategy Promoting Rapid and High-Capacity Lithium Storage by Chemical Scissoring.

Large and rapid lithium storage is hugely demanded for high-energy/power lithium-ion batteries; however, it is difficult to achieve these two indicators simultaneously. Sn-based materials with a (de)alloying mechanism show low working potential and high theoretical capacity, but the huge volume expansion and particle agglomeration of Sn restrict cyclic stability and rate capability. Herein, a soft-in-rigid concept was proposed and achieved by chemical scissoring where a soft Sn-S bond was chosen as chemical tailor to break the Ti-S bond to obtain a loose stacking structure of 1D chain-like Sn1.2Ti0.8S3. The in situ and ex situ (micro)structural characterizations demonstrate that the Sn-S bonds are reduced into Sn domains and such Sn disperses in the rigid Ti-S framework, thus relieving the volume expansion and particle agglomeration by chemical and physical shielding. Benefiting from the merits of large-capacity Sn with an alloying mechanism and high-rate TiS2 with an intercalation mechanism, the Sn1.2Ti0.8S3 anode offers a high specific capacity of 963.2 mA h g-1 at 0.1 A g-1 after 100 cycles and a reversible capacity of 250 mA h g-1 at 10 A g-1 after 3900 cycles. Such a strategy realized by chemical tailoring at the structural unit level would broaden the prospects for constructing joint high-capacity and high-rate LIB anodes.

Galactic cosmic radiation exposure causes multifaceted neurocognitive impairments.

Technological advancements have facilitated the implementation of realistic, terrestrial-based complex 33-beam galactic cosmic radiation simulations (GCR Sim) to now probe central nervous system functionality. This work expands considerably on prior, simplified GCR simulations, yielding new insights into responses of male and female mice exposed to 40-50 cGy acute or chronic radiations relevant to deep space travel. Results of the object in updated location task suggested that exposure to acute or chronic GCR Sim induced persistent impairments in hippocampus-dependent memory formation and reconsolidation in female mice that did not manifest robustly in irradiated male mice. Interestingly, irradiated male mice, but not females, were impaired in novel object recognition and chronically irradiated males exhibited increased aggressive behavior on the tube dominance test. Electrophysiology studies used to evaluate synaptic plasticity in the hippocampal CA1 region revealed significant reductions in long-term potentiation after each irradiation paradigm in both sexes. Interestingly, network-level disruptions did not translate to altered intrinsic electrophysiological properties of CA1 pyramidal cells, whereas acute exposures caused modest drops in excitatory synaptic signaling in males. Ultrastructural analyses of CA1 synapses found smaller postsynaptic densities in larger spines of chronically exposed mice compared to controls and acutely exposed mice. Myelination was also affected by GCR Sim with acutely exposed mice exhibiting an increase in the percent of myelinated axons; however, the myelin sheathes on small calibur (< 0.3 mm) and larger (> 0.5 mm) axons were thinner when compared to controls. Present findings might have been predicted based on previous studies using single and mixed beam exposures and provide further evidence that space-relevant radiation exposures disrupt critical cognitive processes and underlying neuronal network-level plasticity, albeit not to the extent that might have been previously predicted.

The OPG/RANKL/RANK system modulates calcification of common carotid artery in simulated microgravity rats by regulating NF-κB pathway.

Functional and structural adaptation of common carotid artery could be one of the important causes of postflight orthostatic intolerance after microgravity exposure, the mechanisms of which remain unclear. Recent evidence indicates that long-term spaceflight increases carotid artery stiffness, which might present a high risk to astronaut health and postflight working ability. Studies have suggested that vascular calcification is a common pathological change in cardiovascular diseases that is mainly manifested as an increase in vascular stiffness. Therefore, this study investigated whether simulated microgravity induces calcification of common carotid artery and to elucidate the underlying mechanisms. Four-week-old hindlimb-unweighted (HU) rats were used to simulate the deconditioning effects of microgravity on cardiovascular system. We found that simulated microgravity induced vascular smooth muscle cell (VSMC) osteogenic differentiation and medial calcification, increased receptor activator of nuclear factor κB (NF-κB) ligand (RANKL) and RANK expression, and enhanced NF-κB activation in rat common carotid artery. In vitro activation of the RANK pathway with exogenous RANKL, a RANK ligand, increased RANK and osteoprotegerin (OPG) expression in HU rats. Moreover, the expression of osteogenic markers and activation of NF-κB in HU rats were further enhanced by exogenous RANKL but suppressed by the RANK inhibitor osteoprotegerin fusion protein (OPG-Fc). These results indicated that the OPG/RANKL/RANK system modulates VSMC osteogenic differentiation and medial calcification of common carotid artery in simulated microgravity rats by regulating the NF-kB pathway.

Rabi resonance in coherent population trapping: microwave mixing scheme.

Coherent population trapping (CPT) resonance signals have promise in a wide range of applications involving precision sensing. Generally, the CPT phenomenon occurs in a three-level Λ system with a bichromatic phase-coherent light fields. We theoretically and experimentally studied an Rb vapor-cell-based atomic system involving bichromatic CPT optical fields and an external microwave (MW) field simultaneously. In such a mixing scheme, the coherence of the ground states could be controlled either by the Rabi frequency of the microwave field or by the relative phase between the optical fields and the MW field. Moreover, we investigated the Rabi resonance in this mixing scheme. The Rabi frequency of the MW field can be measured SI (International System of Units)-traceably based on the Rabi resonance lineshape, and thus holds the potential to realize intensity stabilization of the optical field in this system. Simple theoretical models and numerical calculations are also presented to explain the experimental results. There is scope to use the proposed technique in future development of SI-traceable optical field strength standards.

Acute, Low-Dose Neutron Exposures Adversely Impact Central Nervous System Function.

A recognized risk of long-duration space travel arises from the elevated exposure astronauts face from galactic cosmic radiation (GCR), which is composed of a diverse array of energetic particles. There is now abundant evidence that exposures to many different charged particle GCR components within acute time frames are sufficient to induce central nervous system deficits that span from the molecular to the whole animal behavioral scale. Enhanced spacecraft shielding can lessen exposures to charged particle GCR components, but may conversely elevate neutron radiation levels. We previously observed that space-relevant neutron radiation doses, chronically delivered at dose-rates expected during planned human exploratory missions, can disrupt hippocampal neuronal excitability, perturb network long-term potentiation and negatively impact cognitive behavior. We have now determined that acute exposures to similar low doses (18 cGy) of neutron radiation can also lead to suppressed hippocampal synaptic signaling, as well as decreased learning and memory performance in male mice. Our results demonstrate that similar nervous system hazards arise from neutron irradiation regardless of the exposure time course. While not always in an identical manner, neutron irradiation disrupts many of the same central nervous system elements as acute charged particle GCR exposures. The risks arising from neutron irradiation are therefore important to consider when determining the overall hazards astronauts will face from the space radiation environment.

Elevated ROS depress mitochondrial oxygen utilization efficiency in cardiomyocytes during acute hypoxia.

Mitochondria are important sites for the production of ATP and the generation of ROS in cells. However, whether acute hypoxia increases ROS generation in cells or affects ATP production remains unclear, and therefore, monitoring the changes in ATP and ROS in living cells in real time is important. In this study, cardiomyocytes were transfected with RoGFP for ROS detection and MitGO-Ateam2 for ATP detection, whereby ROS and ATP production in cardiomyocytes were respectively monitored in real time. Furthermore, the oxygen consumption rate (OCR) of cardiomyocytes was measured. Similar results were produced for adult and neonatal rat cardiomyocytes. Hypoxia (1% O2) reduced the basal OCR, ATP-linked OCR, and maximal OCR in cardiomyocytes compared with these OCR levels in the cardiomyocytes in the normoxic group (21% O2). However, ATP-linked OCR, normalized to maximal OCR, was increased during hypoxia, indicating that the electron leakage of complex III exacerbated the increase of ATP-linked oxygen consumption during hypoxia and vice versa. Combined with the result that cardiomyocytes expressing MitGO-Ateam2 showed a significant decrease in ATP production during hypoxia compared with that of normoxic group, acute hypoxia might depress the mitochondrial oxygen utilization efficiency of the cardiomyocytes. Moreover, cardiomyocytes expressing Cyto-RoGFP or IMS-RoGFP showed an increase in ROS generation in the cytosol and the mitochondrial intermembrane space (IMS) during hypoxia. All of these results indicate that acute hypoxia generated more ROS in complex III and increased mitochondrial oxygen consumption, leading to less ATP production. In conclusion, acute hypoxia depresses the mitochondrial oxygen utilization efficiency by decreasing ATP production and increasing oxygen consumption as a result of the enhanced ROS generation at mitochondrial complex III.

Comparison of hypoxic effects induced by chemical and physical hypoxia on cardiomyocytes.

The degree and duration of chemical hypoxia induced by sodium dithionite (Na2S2O4) have not been reported. It is not yet clear how much reduction in the O2 concentration (physical hypoxia) can lead to hypoxia in cultured cardiomyocytes. In this study, oxygen microelectrodes were used to measure changes in the O2 concentration in media containing different concentrations of Na2S2O4. Then, hypoxic effects of 0.8, 1.0, and 2.0 mM Na2S2O4 or 1%, 3%, and 5% O2 in cultured cardiomyocytes from neonatal rats were observed and compared. The results showed that the O2 concentration failed to remain constant by Na2S2O4 treatment during the 180-minute observation period. Only the 2.0 mM Na2S2O4 group significantly increased the expression of hypoxia-inducible factor 1α (HIF-1α) and hypoxic responses. Notably, 3% O2 only significantly increased the expression of HIF-1α in cardiomyocytes, while 1% O2 not only increased the expression of HIF-1α but also increased the apoptotic rate in cardiomyocytes. These results suggest that Na2S2O4 is not suitable for establishing a hypoxic model in cultured neonatal rat cardiomyocytes, and neonatal rat cardiomyocytes cultured at or below 1% O2 induced significant hypoxic effects, which can be used as a starting O2 concentration for establishing a hypoxic cell model.

Cranial grafting of stem cell-derived microvesicles improves cognition and reduces neuropathology in the irradiated brain.

Cancer survivors face a variety of challenges as they cope with disease recurrence and a myriad of normal tissue complications brought on by radio- and chemotherapeutic treatment regimens. For patients subjected to cranial irradiation for the control of CNS malignancy, progressive and debilitating cognitive dysfunction remains a pressing unmet medical need. Although this problem has been recognized for decades, few if any satisfactory long-term solutions exist to resolve this serious unintended side effect of radiotherapy. Past work from our laboratory has demonstrated the neurocognitive benefits of human neural stem cell (hNSC) grafting in the irradiated brain, where intrahippocampal transplantation of hNSC ameliorated radiation-induced cognitive deficits. Using a similar strategy, we now provide, to our knowledge, the first evidence that cranial grafting of microvesicles secreted from hNSC affords similar neuroprotective phenotypes after head-only irradiation. Cortical- and hippocampal-based deficits found 1 mo after irradiation were completely resolved in animals cranially grafted with microvesicles. Microvesicle treatment was found to attenuate neuroinflammation and preserve host neuronal morphology in distinct regions of the brain. These data suggest that the neuroprotective properties of microvesicles act through a trophic support mechanism that reduces inflammation and preserves the structural integrity of the irradiated microenvironment.

Glycosylated CD147 reduces myocardial collagen cross-linking in cardiac hypertrophy.

The mechanism of transition from chronic pressure overload-induced cardiac hypertrophy to heart failure is still unclear. Angiotensin II (Ang II) may be an important factor that mediates the transition in the end-stage of cardiac hypertrophy. In the present study, Goldblatt two-kidney one-clip (2K1C) rat model was used to simulate Ang II-induced hypertension. The elevated Ang II not only induced the concentric hypertrophy of left ventricle and cardiac fibrosis, but also increased the expression and glycosylation of CD147 in 2K1C rats. The left ventricular structure and function detected by echocardiogram showed a sign of the transition from cardiac hypertrophy to heart failure in 16 weeks of 2K1C rats. Ang II can activate N-acetylglucosamine transferase V (GnT-V), a key enzyme for CD147 glycosylation. Retinoic acid, an agonist of GnT-V, further increased glycosylated CD147, and activated matrix metalloproteinase-2/-9 (MMP-2 and MMP-9) in the hypertrophied left ventricle of 2K1C rat. Meanwhile, collagen cross-linking in the hypertrophied left ventricle significantly reduced in 2K1C rats. On the contrary, tunicamycin, an inhibitor of N-glycan biosynthesis, inhibited glycosylation of CD147 and activity of MMP-2 and MMP-9, and then maintained a stable of collagen cross-linking in the 2K1C rat hearts. The above results suggested that Ang II increased glycosylated CD147 which activated MMP-2 and MMP-9. Collagens were degraded by the activated MMPs and then reduced collagen cross-linking. Finally, the hypertrophied left ventricle was progressively dilated in chronic pressure overload due to losing the limitation of collagen cross-linking. Therefore, the compensated hypertrophy of left ventricle gradually transited to congestive heart failure.

HAb18G/CD147 is involved in TGF-ß-induced epithelial-mesenchymal transition and hepatocellular carcinoma invasion.

Epithelial-mesenchymal transition (EMT) induced by the transforming growth factor beta (TGF-ß) is involved in hepatocarcinogenesis and hepatocellular carcinoma (HCC) metastasis. HAb18G/CD147, a member of the immunoglobulin family, plays an important role in tumor invasion and metastasis. HAb18G/CD147 promotes EMT of hepatocytes through TGF-ß signaling and is transcriptionally regulated by Slug. We investigated the role of HAb18G/CD147 in TGF-ß-induced EMT in HCC invasion. Two human HCC cell lines, SMMC-7721 and HepG2, were used to determine the role of HAb18G/CD147 in EMT. Upregulation of HAb18G/CD147 induced by the high doses of TGF-ß1 in SMMC-7721 (5 ng/mL) and HepG2 cells (10 ng/mL) (P < 0.05). CD147 upregulation was coupled with upregulation of Snail1 and Slug. CD147 knockout significantly decreased the expression of N-cadherin and vimentin, and colony formation ability of SMMC-7721 cells. TGF-ß1 enhanced the migration capacity of SMMC-7721 cells, which was markedly attenuated by CD147 knockdown. Thus, HAb18G/CD147 is involved in TGF-ß-induced EMT and HCC invasion.

Structural plasticity of pyramidal cell neurons measured after FLASH and conventional dose-rate irradiation.

Evidence shows that ultra-high dose-rate FLASH-radiotherapy (FLASH-RT) protects against normal tissue complications and functional decrements in the irradiated brain. Past work has shown that radiation-induced cognitive impairment, neuroinflammation and reduced structural complexity of granule cell neurons were not observed to the same extent after FLASH-RT (> MGy/s) compared to conventional dose-rate (CONV, 0.1 Gy/s) delivery. To explore the sensitivity of different neuronal populations to cranial irradiation and dose-rate modulation, hippocampal CA1 and medial prefrontal cortex (PFC) pyramidal neurons were analyzed by electron and confocal microscopy. Neuron ultrastructural analyses by electron microscopy after 10 Gy FLASH- or CONV-RT exposures indicated that irradiation had little impact on dendritic complexity and synapse density in the CA1, but did increase length and head diameter of smaller non-perforated synapses. Similarly, irradiation caused no change in PFC prelimbic/infralimbic axospinous synapse density, but reductions in non-perforated synapse diameters. While irradiation resulted in thinner myelin sheaths compared to controls, none of these metrics were dose-rate sensitive. Analysis of fluorescently labeled CA1 neurons revealed no radiation-induced or dose-rate-dependent changes in overall dendritic complexity or spine density, in contrast to our past analysis of granule cell neurons. Super-resolution confocal microscopy following a clinical dosing paradigm (3×10Gy) showed significant reductions in excitatory vesicular glutamate transporter 1 and inhibitory vesicular GABA transporter puncta density within the CA1 that were largely dose-rate independent. Collectively, these data reveal that, compared to granule cell neurons, CA1 and mPFC neurons are more radioresistant irrespective of radiation dose-rate.

Interaction of Th17 differentiations-related gene polymorphisms and environmental factors contributing to the disease classification, complications, and surgical risks of Crohn's disease in the Chinese Han population.

OBJECTIVES: Few studies have been conducted on gene-environment interactions in the Chinese population with Crohn's disease (CD). We aimed to investigate the association between single nucleotide polymorphisms (SNPs) on the T helper 17 (Th17) cell and CD susceptibility/performance in Chinese individuals. METHODS: We conducted a case-control and case-only study at the Peking Union Medical College Hospital. Four SNPs related to the Th17 cell pathway genes were prioritized, including rs2284553 (interferon gamma receptor 2), rs7517847 (interleukin 23 receptor), rs7773324 (interferon regulatory factor 4), and rs4263839 (tumor necrosis factor superfamily 15). SNP frequency was calculated, and gene-environment interaction was assessed by multifactor dimensionality reduction analysis. RESULTS: Altogether 159 CD patients and 316 healthy controls were included. All analyzed SNPs were found in Hardy-Weinberg equilibrium (P > 0.05). The frequency of rs2284553-A allele and rs4263839-A allele were lower in CD patients compared with controls (P < 0.05). While the rs4263839-A allele was more prevalent in ileocolonic CD patients than in those with isolated small intestinal or colonic disease (P = 0.035). Gene-environment interactions revealed associations between rs2284553 and breastfeeding, sunshine exposure, and fridge-stored food, affecting age at diagnosis, intestinal involvement, and intestinal stricture. Interaction of rs4263839 and breastfeeding influenced small intestinal lesions and intestinal stricture in CD. CONCLUSIONS: This study provided information on the genetic background in Chinese CD patients. Incorporating these SNPs into predictive models may improve risk assessment and outcome prediction. Gene-environment interaction contributes to the understanding of CD pathogenesis.

A multi-institutional study to investigate the sparing effect after whole brain electron FLASH in mice: Reproducibility and temporal evolution of functional, electrophysiological, and neurogenic endpoints.

BACKGROUND AND PURPOSE: Ultra-high dose-rate radiotherapy (FLASH) has been shown to mitigate normal tissue toxicities associated with conventional dose rate radiotherapy (CONV) without compromising tumor killing in preclinical models. A prominent challenge in preclinical radiation research, including FLASH, is validating both the physical dosimetry and the biological effects across multiple institutions. MATERIALS AND METHODS: We previously demonstrated dosimetric reproducibility of two different electron FLASH devices at separate institutions using standardized phantoms and dosimeters. In this study, tumor-free adult female mice were given 10 Gy whole brain FLASH and CONV irradiation at both institutions and evaluated for the reproducibility and temporal evolution of multiple neurobiological endpoints. RESULTS: FLASH sparing of behavioral performance on novel object recognition (4 months post-irradiation) and of electrophysiologic long-term potentiation (LTP, 5 months post-irradiation) was reproduced between institutions. Differences between FLASH and CONV on the endpoints of hippocampal neurogenesis (Sox2, doublecortin), neuroinflammation (microglial activation), and electrophysiology (LTP) were not observed at early times (48 h to 2 weeks), but recovery of immature neurons by 3 weeks was greater with FLASH. CONCLUSION: In summary, we demonstrated reproducible FLASH sparing effects on the brain between two different beams at two different institutions with validated dosimetry. FLASH sparing effects on the endpoints evaluated manifested at later but not the earliest time points.

In-Plane Porous Graphene: A Promising Anode Material with High Ion Mobility and Energy Storage for Rubidium-Ion Batteries.

Rubidium-ion batteries (RIBs) have received a lot of attention in the quantum field because of their fast release and reversible advantages as alkali sources. However, the anode material of RIBs still follows graphite, whose layer spacing can greatly restrict the diffusion and storage capability of Rb-ions, posing a significant barrier to RIB development. Herein, using first-principles calculations, the potential performance of three kinds of in-plane porous graphene with pore sizes of 5.88 Å (HG588), 10.39 Å (HG1039), and 14.20 Å (HG1420) as anode materials for RIBs was explored. The results indicate that HG1039 appears to be an appropriate anode material for RIBs. HG1039 has excellent thermodynamic stability and a volume expansion of <25% during charge and discharge. The theoretical capacity of HG1039 is up to 1810 mA h g-1, which is ∼5 times higher than that of the existing graphite-based lithium-ion batteries. Importantly, not only HG1039 enables the diffusion of Rb-ions at the three-dimensional level but also the electrode-electrolyte interface formed by HG1039 and Rb-ß-Al2O3 facilitates the arrangement and transfer of Rb-ions. In addition, HG1039 is metallic, and its outstanding ionic conductivity (diffusion energy barrier of only 0.04 eV) and electronic conductivity indicates superior rate capability. These characteristics make HG1039 an appealing anode material for RIBs.

Accelerating ion/electron transport by engineering an indium-based heterostructure toward large and reversible lithium storage.

The high activity of the In2O3/In2S3 heterostructure can be activated into homogeneous In2OxS3-x nanodots, thereupon stabilizing the subsequent cycles. The In2O3/In2S3 can offer a high capacity of 1140 mA h g-1 at 0.1 A g-1 after 290 cycles, and even at 1 A g-1, it harvests a reversible capacity of 900 mA h g-1 after 600 cycles.

Uncovering the Protective Neurologic Mechanisms of Hypofractionated FLASH Radiotherapy.

Implementation of ultra-high dose-rate FLASH radiotherapy (FLASH-RT) is rapidly gaining traction as a unique cancer treatment modality able to dramatically minimize normal tissue toxicity while maintaining antitumor efficacy compared with standard-of-care radiotherapy at conventional dose rate (CONV-RT). The resultant improvements in the therapeutic index have sparked intense investigations in pursuit of the underlying mechanisms. As a preamble to clinical translation, we exposed non-tumor-bearing male and female mice to hypofractionated (3 × 10 Gy) whole brain FLASH- and CONV-RT to evaluate differential neurologic responses using a comprehensive panel of functional and molecular outcomes over a 6-month follow-up. In each instance, extensive and rigorous behavioral testing showed FLASH-RT to preserve cognitive indices of learning and memory that corresponded to a similar protection of synaptic plasticity as measured by long-term potentiation (LTP). These beneficial functional outcomes were not found after CONV-RT and were linked to a preservation of synaptic integrity at the molecular (synaptophysin) level and to reductions in neuroinflammation (CD68+ microglia) throughout specific brain regions known to be engaged by our selected cognitive tasks (hippocampus, medial prefrontal cortex). Ultrastructural changes in presynaptic/postsynaptic bouton (Bassoon/Homer-1 puncta) within these same regions of the brain were not found to differ in response to dose rate. With this clinically relevant dosing regimen, we provide a mechanistic blueprint from synapse to cognition detailing how FLASH-RT reduces normal tissue complications in the irradiated brain. Significance: Functional preservation of cognition and LTP after hypofractionated FLASH-RT are linked to a protection of synaptic integrity and a reduction in neuroinflammation over protracted after irradiation times.

Elucidating the neurological mechanism of the FLASH effect in juvenile mice exposed to hypofractionated radiotherapy.

BACKGROUND: Ultrahigh dose-rate radiotherapy (FLASH-RT) affords improvements in the therapeutic index by minimizing normal tissue toxicities without compromising antitumor efficacy compared to conventional dose-rate radiotherapy (CONV-RT). To investigate the translational potential of FLASH-RT to a human pediatric medulloblastoma brain tumor, we used a radiosensitive juvenile mouse model to assess adverse long-term neurological outcomes. METHODS: Cohorts of 3-week-old male and female C57Bl/6 mice exposed to hypofractionated (2 × 10 Gy, FLASH-RT or CONV-RT) whole brain irradiation and unirradiated controls underwent behavioral testing to ascertain cognitive status four months posttreatment. Animals were sacrificed 6 months post-irradiation and tissues were analyzed for neurological and cerebrovascular decrements. RESULTS: The neurological impact of FLASH-RT was analyzed over a 6-month follow-up. FLASH-RT ameliorated neurocognitive decrements induced by CONV-RT and preserved synaptic plasticity and integrity at the electrophysiological (long-term potentiation), molecular (synaptophysin), and structural (Bassoon/Homer-1 bouton) levels in multiple brain regions. The benefits of FLASH-RT were also linked to reduced neuroinflammation (activated microglia) and the preservation of the cerebrovascular structure, by maintaining aquaporin-4 levels and minimizing microglia colocalized to vessels. CONCLUSIONS: Hypofractionated FLASH-RT affords significant and long-term normal tissue protection in the radiosensitive juvenile mouse brain when compared to CONV-RT. The capability of FLASH-RT to preserve critical cognitive outcomes and electrophysiological properties over 6-months is noteworthy and highlights its potential for resolving long-standing complications faced by pediatric brain tumor survivors. While care must be exercised before clinical translation is realized, present findings document the marked benefits of FLASH-RT that extend from synapse to cognition and the microvasculature.

FLASH-RT does not affect chromosome translocations and junction structures beyond that of CONV-RT dose-rates.

BACKGROUND AND PURPOSE: The impact of radiotherapy (RT) at ultra high vs conventional dose rate (FLASH vs CONV) on the generation and repair of DNA double strand breaks (DSBs) is an important question that remains to be investigated. Here, we tested the hypothesis as to whether FLASH-RT generates decreased chromosomal translocations compared to CONV-RT. MATERIALS AND METHODS: We used two FLASH validated electron beams and high-throughput rejoin and genome-wide translocation sequencing (HTGTS-JoinT-seq), employing S. aureus and S. pyogenes Cas9 "bait" DNA double strand breaks (DSBs) in HEK239T cells, to measure differences in bait-proximal repair and their genome-wide translocations to "prey" DSBs generated after various irradiation doses, dose rates and oxygen tensions (normoxic, 21% O2; physiological, 4% O2; hypoxic, 2% and 0.5% O2). Electron irradiation was delivered using a FLASH capable Varian Trilogy and the eRT6/Oriatron at CONV (0.08-0.13 Gy/s) and FLASH (1x102-5x106 Gy/s) dose rates. Related experiments using clonogenic survival and γH2AX foci in the 293T and the U87 glioblastoma lines were also performed to discern FLASH-RT vs CONV-RT DSB effects. RESULTS: Normoxic and physioxic irradiation of HEK293T cells increased translocations at the cost of decreasing bait-proximal repair but were indistinguishable between CONV-RT and FLASH-RT. Although no apparent increase in chromosome translocations was observed with hypoxia-induced apoptosis, the combined decrease in oxygen tension with IR dose-rate modulation did not reveal significant differences in the level of translocations nor in their junction structures. Furthermore, RT dose rate modality on U87 cells did not change γH2AX foci numbers at 1- and 24-hours post-irradiation nor did this affect 293T clonogenic survival. CONCLUSION: Irrespective of oxygen tension, FLASH-RT produces translocations and junction structures at levels and proportions that are indistinguishable from CONV-RT.

Human neural stem cell-derived extracellular vesicles mitigate hallmarks of Alzheimer's disease.

BACKGROUND: Regenerative therapies to mitigate Alzheimer's disease (AD) neuropathology have shown very limited success. In the recent era, extracellular vesicles (EVs) derived from multipotent and pluripotent stem cells have shown considerable promise for the treatment of dementia and many neurodegenerative conditions. METHODS: Using the 5xFAD accelerated transgenic mouse model of AD, we now show the regenerative potential of human neural stem cell (hNSC)-derived EVs on the neurocognitive and neuropathologic hallmarks in the AD brain. Two- or 6-month-old 5xFAD mice received single or two intra-venous (retro-orbital vein, RO) injections of hNSC-derived EVs, respectively. RESULTS: RO treatment using hNSC-derived EVs restored fear extinction memory consolidation and reduced anxiety-related behaviors 4-6 weeks post-injection. EV treatment also significantly reduced dense core amyloid-beta plaque accumulation and microglial activation in both age groups. These results correlated with partial restoration of homeostatic levels of circulating pro-inflammatory cytokines in the AD mice. Importantly, EV treatment protected against synaptic loss in the AD brain that paralleled improved cognition. MiRNA analysis of the EV cargo revealed promising candidates targeting neuroinflammation and synaptic function. CONCLUSIONS: Collectively, these data demonstrate the neuroprotective effects of systemic administration of stem cell-derived EVs for remediation of behavioral and molecular AD neuropathologies.

miR­302c­3p and miR­520a­3p suppress the proliferation of cervical carcinoma cells by targeting CXCL8.

The aim of the present study was to identify the differentially expressed microRNAs (miRs) in cervical carcinoma (CC) tissues and cells and to explore the function of miR­302c­3p and miR­520a­3p in the proliferation of CC cells. Potential dysregulated miRNAs in CC tissues and tumour­adjacent tissues were detected. Reverse transcription­quantitative PCR (RT­qPCR) was performed to determine the expression of miR­302c­3p, miR­520a­3p and CXCL8 in CC tissues and cell lines. The target genes of the miRNAs were predicted using miRTarBase and verified by luciferase reporter assays. RT­qPCR and western blotting were performed to measure the expression of C­X­C motif ligand (CXCL)8 after transfection. The effect on proliferation was verified by Cell Counting Kit assay and ethynyl­2­deoxyuridine staining. Flow cytometry was utilised to assess the effect on apoptosis. In the present study, miR­302c­3p and miR­520a­3p were markedly downregulated in CC cell lines compared to the normal cervical cell line H8. Functionally, overexpression of miR­302c­3p and/or miR­520a­3p inhibited proliferation and promoted the apoptosis of CC cell lines in vitro, while the knockdown of miR­302c­3p and/or miR­520a­3p had the opposite effect. Furthermore, miR­302c­3p and miR­520a­3p could both bind to CXCL8. Inhibition of CXCL8 in combination with miR­302c­3p and/or miR­520a­3p overexpression exerted proliferation­suppressive and apoptosis­stimulating effects on CC cells, whereas restoring CXCL8 attenuated the miR­302c­3p­ and miR­520a­3p­induced anti­proliferative and pro­apoptotic effects. miR­302c­3p and miR­520a­3p suppress the proliferation of CC cells by downregulating the expression of CXCL8, which may provide a novel target for the treatment of CC.