Optimization of the stroke hospital selection strategy and the distribution of endovascular thrombectomy resources.

Nowadays, emergency medical technicians (EMTs) decide to send a suspected stroke patient to a primary stroke center (PSC) or to an endovascular thrombectomy (EVT)-capable hospital, based on the Cincinnati Prehospital Stroke Scale (CPSS) and the number of symptoms a patient presents at the scene. Based on existing studies, the patient is likely to have a better functional outcome after three months if the time between the onset of symptoms and receiving EVT treatment is shorter. However, if an acute ischemic stroke (AIS) patient with large vessel occlusion (LVO) is first sent to a PSC, and then needs to be transferred to an EVT-capable hospital, the time to get definitive treatment is significantly increased. For this purpose, We formulate an integer programming model to minimize the expected time to receive a definitive treatment for stroke patients. We then use real-world data to verify the validity of the model. Also, we expand our model to find the optimal redistribution and centralization of EVT resources. It will enable therapeutic teams to increase their experience and skills more efficiently within a short period of time.

JMJ28 guides sequence-specific targeting of ATX1/2-containing COMPASS-like complex in Arabidopsis.

Despite extensive investigations in mammals and yeasts, the importance and specificity of COMPASS-like complex, which catalyzes histone 3 lysine 4 methylation (H3K4me), are not fully understood in plants. Here, we report that JMJ28, a Jumonji C domain-containing protein in Arabidopsis, recognizes specific DNA motifs through a plant-specific WRC domain and acts as an interacting factor to guide the chromatin targeting of ATX1/2-containing COMPASS-like complex. JMJ28 associates with COMPASS-like complex in vivo via direct interaction with RBL. The DNA-binding activity of JMJ28 is essential for both the targeting specificity of ATX1/2-COMPASS and the deposition of H3K4me at specific loci but exhibit functional redundancy with alternative COMPASS-like complexes at other loci. Finally, we demonstrate that JMJ28 is a negative regulator of plant immunity. In summary, our findings reveal a plant-specific recruitment mechanism of COMPASS-like complex. These findings help to gain deeper insights into the regulatory mechanism of COMPASS-like complex in plants.

Molecular basis of locus-specific H3K9 methylation catalyzed by SUVH6 in plants.

Dimethylated histone H3 Lys9 (H3K9me2) is a conserved heterochromatic mark catalyzed by SUPPRESSOR OF VARIEGATION 3-9 HOMOLOG (SUVH) methyltransferases in plants. However, the mechanism underlying the locus specificity of SUVH enzymes has long been elusive. Here, we show that a conserved N-terminal motif is essential for SUVH6-mediated H3K9me2 deposition in planta. The SUVH6 N-terminal peptide can be recognized by the bromo-adjacent homology (BAH) domain of the RNA- and chromatin-binding protein ANTI-SILENCING 1 (ASI1), which has been shown to function in a complex to confer gene expression regulation. Structural data indicate that a classic aromatic cage of ASI1-BAH domain specifically recognizes an arginine residue of SUVH6 through extensive hydrogen bonding interactions. A classic aromatic cage of ASI1 specifically recognizes an arginine residue of SUVH6 through extensive cation-π interactions, playing a key role in recognition. The SUVH6-ASI1 module confers locus-specific H3K9me2 deposition at most SUVH6 target loci and gives rise to distinct regulation of gene expression depending on the target loci, either conferring transcriptional silencing or posttranscriptional processing of mRNA. More importantly, such mechanism is conserved in multiple plant species, indicating a coordinated evolutionary process between SUVH6 and ASI1. In summary, our findings uncover a conserved mechanism for the locus specificity of H3K9 methylation in planta. These findings provide mechanistic insights into the delicate regulation of H3K9 methylation homeostasis in plants.

NUCLEAR PORE ANCHOR and EARLY IN SHORT DAYS 4 negatively regulate abscisic acid signaling by inhibiting Snf1-related protein kinase2 activity and stability in Arabidopsis.

Abscisic acid (ABA) is a key regulator of plant responses to abiotic stresses, such as drought. Abscisic acid receptors and coreceptors perceive ABA to activate Snf1-related protein kinase2s (SnRK2s) that phosphorylate downstream effectors, thereby activating ABA signaling and the stress response. As stress responses come with fitness penalties for plants, it is crucial to tightly control SnRK2 kinase activity to restrict ABA signaling. However, how SnRK2 kinases are inactivated remains elusive. Here, we show that NUCLEAR PORE ANCHOR (NUA), a nuclear pore complex (NPC) component, negatively regulates ABA-mediated inhibition of seed germination and post-germination growth, and drought tolerance in Arabidopsis thaliana. The role of NUA in response to ABA depends on SnRK2.2 and SnRK2.3 for seed germination and on SnRK2.6 for drought. NUA does not directly inhibit the phosphorylation of these SnRK2s or affects their abundance. However, the NUA-interacting protein EARLY IN SHORT DAYS 4 (ESD4), a SUMO protease, negatively regulates ABA signaling by directly interacting with and inhibiting SnRK2 phosphorylation and protein levels. More importantly, we demonstrated that SnRK2.6 can be SUMOylated in vitro, and ESD4 inhibits its SUMOylation. Taken together, we identified NUA and ESD4 as SnRK2 kinase inhibitors that block SnRK2 activity, and reveal a mechanism whereby NUA and ESD4 negatively regulate plant responses to ABA and drought stress possibly through SUMOylation-dependent regulation of SnRK2s.

A fungal effector suppresses the nuclear export of AGO1-miRNA complex to promote infection in plants.

Communication between interacting organisms via bioactive molecules is widespread in nature and plays key roles in diverse biological processes. Small RNAs (sRNAs) can travel between host plants and filamentous pathogens to trigger transkingdom RNA interference (RNAi) in recipient cells and modulate plant defense and pathogen virulence. However, how fungal pathogens counteract transkingdom antifungal RNAi has rarely been reported. Here we show that a secretory protein VdSSR1 (secretory silencing repressor 1) from Verticillium dahliae, a soil-borne phytopathogenic fungus that causes wilt diseases in a wide range of plant hosts, is required for fungal virulence in plants. VdSSR1 can translocate to plant nucleus and serve as a general suppressor of sRNA nucleocytoplasmic shuttling. We further reveal that VdSSR1 sequesters ALY family proteins, adaptors of the TREX complex, to interfere with nuclear export of the AGO1­microRNA (AGO1­miRNA) complex, leading to a great attenuation in cytoplasmic AGO1 protein and sRNA levels. With this mechanism, V. dahliae can suppress the accumulation of mobile plant miRNAs in fungal cells and succedent transkingdom silencing of virulence genes, thereby increasing its virulence in plants. Our findings reveal a mechanism by which phytopathogenic fungi antagonize antifungal RNAi-dependent plant immunity and expand the understanding on the complex interaction between host and filamentous pathogens.

Prehospital-Stroke-Scale Parameterized Hospital Selection Protocol for Suspected Stroke Patients Considering Door-to-Treatment Durations.

Background To mitigate uncertainty that may arise in the judgment of emergency medical technicians when relying on a prehospital stroke scale at the scene, we propose a hospital selection protocol that considers the uncertainty of a prehospital stroke scale and the actual door-to-treatment durations, and we have developed a web-based system to be used with mobile devices. Methods and Results This hospital selection protocol incorporates real-time, estimated transport time obtained from Google Maps, historical median door-to-treatment duration at hospitals that only provide the standard intravenous thrombolysis treatment, and at hospitals with endovascular thrombectomy for probable large-vessel occlusion cases. We have validated the efficiency of the proposed protocol and compared it with other strategies used by emergency medical technicians when deciding on a receiving hospital. Using the proposed protocol for the triage reduces the time from onset to receiving definitive treatment by nearly 11 minutes. We found that the nearest endovascular thrombectomy-capable hospital from the scene may not be the most ideal if the door-to-treatment durations are discriminative. The results show that, when the tolerable bypass transport threshold and administration time are reduced to 9 minutes and 30.5 minutes, respectively, 228 patients out of 7678 cases, whose receiving hospitals were changed to endovascular thrombectomy-capable hospitals, received definitive treatment in a shorter time. The results of our analysis give recommendations for appropriate allowable bypass transport time for regional planning. Conclusions By applying almost-real value parameters, we have validated a web-based model, which can be universally adapted for optimal, time-saving hospital selection for patients with stroke.

Expanding resources of endovascular thrombectomy: An optimization model.

BACKGROUND/PURPOSE: Recently optimized models for selecting the locations of hospitals capable of providing endovascular thrombectomy (EVT) did not consider the accuracy of the prehospital stroke scale assessment and possibility of secondary transport. Our study aimed to propose a new model for selecting existing hospitals with intravenous thrombolysis capability to become EVT-capable hospitals. METHODS: A sequential order was provided to upgrade hospitals providing intravenous thrombolysis, using a mixed integer programming model based on current medical resource allocation. In addition, we drafted a centralized plan to redistribute existing EVT resources by redetermining locations of EVT-capable hospitals. Using historical data of 7679 on-scene patients with suspected stroke, the model was implemented to determine the hospital that maximizes the number of patients receiving EVT treatment within call-to-definitive-treatment time. RESULTS: All suspected stroke patients were sent to EVT-capable hospitals directly under the current medical resource allocation model. After upgrading one additional hospital to become an EVT-capable hospital, the percentage of patients receiving definitive treatment within the standard call-to-definitive-treatment time was elevated from 68.82% to 72.97%. In the model, assuming that there is no hospital providing EVT, all patients suspected of stroke will be sent to EVT-capable hospitals directly after upgrading three or more hospitals to be able to provide treatment. CONCLUSION: All patients eligible for acute stroke treatment are sent to EVT-capable hospitals in the simulation under the current medical resource allocation model. This model can be utilized to provide insights for capacity redistribution in other regions.

Redistributing medical resources for a bypass strategy for large vessel occlusion: a community-based study.

BACKGROUND: A bypass strategy for large vessel occlusion (LVO) benefits patients receiving endovascular thrombectomy (EVT), but may delay some patients from receiving IV thrombolysis. However, patient centralization has been shown to improve outcomes. OBJECTIVE: To understand the current coverage of medical services for patients with stroke, and to identify the best coverage under different medical resource redistribution to help balance medical equality and patient centralization. METHODS: This 6-year geographic study of 7679 on-scene patients with suspected stroke with a positive Cincinnati Prehospital Stroke Scale (CPSS) score identified 4037 patients with all three CPSS items who were suspected as having an LVO. Geographic, population, and patient coverage rates for hospitals providing IV thrombolysis and those providing EVT were identified according to hospital service areas, defined as geographic districts with access to a hospital within a ≤15 min off-peak driving time estimated using Google Maps. Moreover, we estimated the effects on resource redistribution when implementing a bypass strategy. RESULTS: Geographic coverage rates for hospitals providing IV thrombolysis and those providing EVT were 64.75% and 56.62%, respectively, and population coverage rates were 97.30% and 92.72%, respectively. The service areas of hospitals providing IV thrombolysis covered 93.77% of patients with suspected stroke, and those of hospitals providing EVT covered 87.89% of patients with suspected LVO. The number of hospitals providing IV thrombolysis and those providing EVT could be reduced to six and two hospitals, respectively, without affecting hospital arrival time when implementing a bypass strategy. CONCLUSION: Hospitals providing IV thrombolysis and EVT could be reduced without reducing medical equality.

Pyrenylpyridines: Sky-Blue Emitters for Organic Light-Emitting Diodes.

A novel sky-blue-emitting tripyrenylpyridine derivative, 2,4,6-tri(1-pyrenyl)pyridine (2,4,6-TPP), has been synthesized using a Suzuki coupling reaction and compared with three previously reported isomeric dipyrenylpyridine (DPP) analogues (2,4-di(1-pyrenyl)pyridine (2,4-DPP), 2,6-di(1-pyrenyl)pyridine (2,6-DPP), and 3,5-di(1-pyrenyl)pyridine (3,5-DPP)). As revealed by single-crystal X-ray analysis and computational simulations, all compounds possess highly twisted conformations in the solid state with interpyrene torsional angles of 42.3°-57.2°. These solid-state conformations and packing variations of pyrenylpyridines could be correlated to observed variations in physical characteristics such as photo/thermal stability and spectral properties, but showed only marginal influence on electrochemical properties. The novel derivative, 2,4,6-TPP, exhibited the lowest degree of crystallinity as revealed by powder X-ray diffraction analysis and formed amorphous thin films as verified using grazing-incidence wide-angle X-ray scattering. This compound also showed high thermal/photo stability relative to its disubstituted analogues (DPPs). Thus, a nondoped organic light-emitting diode (OLED) prototype was fabricated using 2,4,6-TPP as the emissive layer, which displayed a sky-blue electroluminescence with Commission Internationale de L'Eclairage (CIE) coordinates of (0.18, 0.34). This OLED prototype achieved a maximum external quantum efficiency of 6.0 ± 1.2% at 5 V. The relatively high efficiency for this simple-architecture device reflects a good balance of electron and hole transporting ability of 2,4,6-TPP along with efficient exciton formation in this material and indicates its promise as an emitting material for design of blue OLED devices.

Amplifying fluorescent conjugated polymer sensor for singlet oxygen detection.

A "higher energy gap" concept was applied towards designing an efficient turn-on amplifying sensor for singlet oxygen - an important biomedical and environmental monitoring analytical target. The concept is based on modulation of intramolecular energy transfer in fluorescent conjugated polymers through the formation of a higher energy gap "roadblock" upon reaction with a target analyte. The polymer sensor incorporates 1,4-disubstituted tetracene units which act as reactive sites for singlet oxygen. The resulting polymer sensor demonstrates significant fluorescent signal amplification and a broader analyte detection range relative to a corresponding small-molecule sensor.

Influence of Anion Variations on Morphological, Spectral, and Physical Properties of the Propidium Luminophore.

Propidium iodide (3,8-diamino-5-[3-(diethylmethylammonio)propyl]-6-phenylphenanthridinium diiodide, [P][I]), is a well-known red fluorescent dye that is widely used for biological applications such as staining. In this study, we have replaced the iodide counteranion of [P][I] with three hydrophobic and bulky organic anions, trifluoromethanesulfonate/[TfO], bis(trifluoromethanesulfonyl)imide/[NTf2], and bis(perfluoroethylsulfonyl)imide/[BETI], and have thus obtained a propidium-derived group of uniform materials based on organic salts (PGUMBOS). The morphological, spectral, and physical properties of these materials were investigated in order to understand the impact of anion variations. While [P][I] is a crystalline solid, propidium salts with [BETI] or [NTf2] counteranions, i.e., [P][BETI] and [P][NTf2], have significantly lower crystallinity as reflected in powder X-ray diffraction data. In addition, [P][BETI] and [P][NTf2] exhibited improved photothermal stability as compared to [P][I] when examined using thermogravimetric analysis and time-dependent kinetic fluorescence experiments under the given experimental conditions. Spectral and electronic properties of the propidium luminophore were not significantly changed upon anion variations, although fluorescence lifetimes and quantum yields showed a systematic increase with decreasing solvent polarity. The experimental HOMO-LUMO energy gaps of these compounds were ∼2 eV with energies of HOMO and LUMO orbitals obtained as -5.15 (±0.08) and -3.19 (±0.08) eV.

Semaphorin-1a prevents Drosophila olfactory projection neuron dendrites from mis-targeting into select antennal lobe regions.

Elucidating how appropriate neurite patterns are generated in neurons of the olfactory system is crucial for comprehending the construction of the olfactory map. In the Drosophila olfactory system, projection neurons (PNs), primarily derived from four neural stem cells (called neuroblasts), populate their cell bodies surrounding to and distribute their dendrites in distinct but overlapping patterns within the primary olfactory center of the brain, the antennal lobe (AL). However, it remains unclear whether the same molecular mechanisms are employed to generate the appropriate dendritic patterns in discrete AL glomeruli among PNs produced from different neuroblasts. Here, by examining a previously explored transmembrane protein Semaphorin-1a (Sema-1a) which was proposed to globally control initial PN dendritic targeting along the dorsolateral-to-ventromedial axis of the AL, we discover a new role for Sema-1a in preventing dendrites of both uni-glomerular and poly-glomerular PNs from aberrant invasion into select AL regions and, intriguingly, this Sema-1a-deficient dendritic mis-targeting phenotype seems to associate with the origins of PNs from which they are derived. Further, ectopic expression of Sema-1a resulted in PN dendritic mis-projection from a select AL region into adjacent glomeruli, strengthening the idea that Sema-1a plays an essential role in preventing abnormal dendritic accumulation in select AL regions. Taken together, these results demonstrate that Sema-1a repulsion keeps dendrites of different types of PNs away from each other, enabling the same types of PN dendrites to be sorted into destined AL glomeruli and permitting for functional assembly of olfactory circuitry.

Tandem isomerization and C-H activation: regioselective hydroheteroarylation of allylarenes.

The first Ni-promoted prototype reaction based on the tandem C-H activation of heteroarenes with alkene isomerization is demonstrated, leading to the branched hydroheteroarylation products. Simultaneously, the reaction selectivity can be chemically switched to linear adducts through Ni-Al tandem catalysis.

Application of RNA silencing to plant disease resistance.

To reduce the losses caused by plant pathogens, plant biologists have adopted numerous methods to engineer resistant plants. Among them, RNA silencing-based resistance has been a powerful tool that has been used to engineer resistant crops during the last two decades. Based on this mechanism, diverse approaches were developed. In this review, we focus on the application of RNA silencing to produce plants that are resistant to plant viruses such as RNA and DNA viruses, viroids, insects, and the recent expansion to fungal pathogens.

Artificial MicroRNAs highly accessible to targets confer efficient virus resistance in plants.

Short-hairpin RNAs based on microRNA (miRNA) precursors to express the artificial miRNAs (amiRNAs) can specifically induce gene silencing and confer virus resistance in plants. The efficacy of RNA silencing depends not only on the nature of amiRNAs but also on the local structures of the target mRNAs. However, the lack of tools to accurately and reliably predict secondary structures within long RNAs makes it very hard to predict the secondary structures of a viral genome RNA in the natural infection conditions in vivo. In this study, we used an experimental approach to dissect how the endogenous silencing machinery acts on the 3' untranslated region (UTR) of the Cucumber mosaic virus (CMV) genome. Transiently expressed 3'UTR RNAs were degraded by site-specific cleavage. By comparing the natural cleavage hotspots within the 3'UTR of the CMV-infected wild-type Arabidopsis to those of the triple dcl2/3/4 mutant, we acquired true small RNA programmed RNA-induced silencing complex (siRISC)-mediated cleavage sites to design valid amiRNAs. We showed that the tRNA-like structure within the 3'UTR impeded target site access and restricted amiRNA-RISC-mediated cleavage of the target viral RNA. Moreover, target recognition in the less-structured area also influenced siRISC catalysis, thereby conferring different degrees of resistance to CMV infection. Transgenic plants expressing the designed amiRNAs that target the putative RISC accessible target sites conferred high resistance to the CMV challenge from both CMV subgroup strains. Our work suggests that the experimental approach is credible for studying the course of RISC target recognition to engineer effective gene silencing and virus resistance in plants by amiRNAs.