Rh-Catalyzed [4 + 1] Reaction of Cyclopropyl-Capped Dienes (but not Common Dienes) and Carbon Monoxide: Reaction Development and Mechanistic Study.

Transition-metal-catalyzed [4 + 1] reaction of dienes and carbon monoxide (CO) is the most straightforward and easily envisioned cyclization for the synthesis of five-membered carbocycles, which are ubiquitously found in natural products and functional molecules. Unfortunately, no test of this reaction was reported, and consequently, chemists do not know whether such kind of reaction works or not. Herein, we report that the [4 + 1] reaction of common dienes and CO cannot work, at least under the catalysis of [Rh(cod)Cl]2. However, using cyclopropyl-capped dienes (also named allylidenecyclopropanes) as substrates, the corresponding [4 + 1] reaction with CO proceeds smoothly in the presence of [Rh(cod)Cl]2. This [4 + 1] reaction, with a broad scope, provides efficient access to five-membered carbocyclic compounds of spiro[2.4]hept-6-en-4-ones. The [4 + 1] cycloadducts can be further transformed into other molecules by using the unique chemistry of cyclopropyl groups present in these molecules. The mechanism of this [4 + 1] reaction has been investigated by quantum chemical calculations, uncovering that cyclopropyl-capped dienes are strained dienes and the oxidative cyclization step in the [4 + 1] catalytic cycle can release this (angular) strain both kinetically and thermodynamically. The strain release in this step then propagates to all followed CO coordination/CO insertion/reductive elimination steps in the [4 + 1] catalytic cycle, helping the realization of this cycloaddition reaction. In contrast, common dienes (including cyclobutyl-capped dienes) do not have such advantages and their [4 + 1] reaction suffers from energy penalty in all steps involved in the [4 + 1] catalytic cycle. The reactivity of ene-allenes for the [4 + 1] reaction with CO is also discussed.

Functional characterization and regulatory mechanism of wheat CPK34 kinase in response to drought stress.

BACKGROUND: Drought is one of the most adverse environmental factors limiting crop productions and it is important to identify key genetic determinants for food safety. Calcium-dependent protein kinases (CPKs) are known to be involved in plant growth, development, and environmental stresses. However, biological functions and regulatory mechanisms of many plant CPKs have not been explored. In our previous study, abundance of the wheat CPK34 (TaCPK34) protein was remarkably upregulated in wheat plants suffering from drought stress, inferring that it could be involved in this stress. Therefore, here we further detected its function and mechanism in response to drought stress. RESULTS: Transcripts of the TaCPK34 gene were significantly induced after PEG-stimulated water deficiency (20% PEG6000) or 100 µM abscisic acid (ABA) treatments. The TaCPK34 gene was transiently silenced in wheat genome by using barley stripe mosaic virus-induced silencing (BSMV-VIGS) method. After 14 days of drought stress, the transiently TaCPK34-silenced wheat seedlings showed more sensitivity compared with control, and the plant biomasses and relative water contents significantly decreased, whereas soluble sugar and MDA contents increased. The iTRAQ-based quantitative proteomics was employed to measure the protein expression profiles in leaves of the transiently TaCPK34-silenced wheat plants after drought stress. There were 6103 proteins identified, of these, 51 proteins exhibited significantly altered abundance, they were involved in diverse function. And sequence analysis on the promoters of genes, which encoded the above identified proteins, indicated that some promoters harbored some ABA-responsive elements. We determined the interactions between TaCPK34 and three identified proteins by using bimolecular fluorescent complementation (BiFC) method and our data indicated that TaCPK34directly interacted with the glutathione S-transferase 1 and prx113, respectively. CONCLUSIONS: Our study suggested that the TaCPK34 gene played positive roles in wheat response to drought stress through directly or indirectly regulating the expression of ABA-dependent manner genes, which were encoding identified proteins from iTRAQ-based quantitative proteomics. And it could be used as one potential gene to develop crop cultivars with improved drought tolerance.

[The influence of reward motivation on emotion regulation].

The influence of reward on behavior is one of the hottest research subjects in psychological research. Reward-induced motivation promotes the performance of the participants. In the field of emotional processing, the reward can influence the individual's processing of emotional information, but previous studies have not directly discussed the effect of reward on emotional regulation. The present study focused on whether emotional regulation ability would be improved under the reward condition. Experiment 1 and 2 investigated the effect of reward on negative emotional down-regulation and positive emotional up-regulation respectively. In experiment 1, monetary reward stimulation was introduced on the basis of the classic emotion regulation paradigm, and the subjects were asked to regulate their negative emotion under the condition of reward or non-reward, and evaluate their current affective state subsequently. Similar to experiment 1, experiment 2 required subjects to up-regulate positive emotions under the condition of reward or non-reward. The results of experiment 1 showed that under the reward condition, the negative emotional regulation effect was significantly higher than that under the non-reward condition (P < 0.05). Experiment 2 also showed that compared to non-reward condition, the positive emotion regulation effect was significantly increased under the reward condition (P < 0.05). These results suggested that compared to non-reward condition, participants can regulate their emotion better under the condition of the reward. It is worth noting that the results of Experiment 1 and 2 may be caused by the incentive motivation induced by monetary stimulus, or the positive emotion caused by positive value of money information. Therefore, we carried out experiment 3 and 4 to explore whether the positive emotions induced by money itself can influence the emotional regulation of individuals. In experiment 3, the money pictures were used to induce the positive emotions of subjects, and the subjects were asked to regulate their negative emotion after the presence of money pictures or non-monetary picture, and evaluate their current affective state subsequently. Similarly, experiment 4 required subjects to regulate their positive emotion after the presence of money pictures. The results of experiment 3 and 4 showed that there was no significant difference in the subjects' scores of emotional pleasantness after the presence of money pictures or non-monetary picture (P < 0.05). The results of experiment 3 and 4 excluded the possibility that the positive emotions induced by simple money stimulus pictures could improve individual's emotional regulation ability. To sum up, the improvement of individual's emotional regulation ability was indeed driven by reward motivation in this study, that is, the motivation induced by reward can effectively promote individual's emotional regulation ability.

Arene Reduction by Rh/Pd or Rh/Pt under 1 atm Hydrogen Gas and Room Temperature.

Current methods for arene hydrogenation generally need either harsh reaction conditions or complex catalyst preparation. Here we describe a mild and convenient protocol that only utilizes commercially available catalysts. Using [Rh(nbd)Cl]2 and Pd/C together as catalysts, arenes bearing various functional groups can be hydrogenated under 1 atm of H2 at room temperature. This arene hydrogenation can also be achieved using catalysts of [Rh(cod)Cl]2 and PtO2, thus avoiding glovebox manipulations and simplifying the reaction procedure.

Retinal vascular morphological characteristics in diabetic retinopathy: an artificial intelligence study using a transfer learning system to analyze ultra-wide field images.

AIM: To investigate the morphological characteristics of retinal vessels in patients with different severity of diabetic retinopathy (DR) and in patients with or without diabetic macular edema (DME). METHODS: The 239 eyes of DR patients and 100 eyes of healthy individuals were recruited for the study. The severity of DR patients was graded as mild, moderate and severe non-proliferative diabetic retinopathy (NPDR) according to the international clinical diabetic retinopathy (ICDR) disease severity scale classification, and retinal vascular morphology was quantitatively analyzed in ultra-wide field images using RU-net and transfer learning methods. The presence of DME was determined by optical coherence tomography (OCT), and differences in vascular morphological characteristics were compared between patients with and without DME. RESULTS: Retinal vessel segmentation using RU-net and transfer learning system had an accuracy of 99% and a Dice metric of 0.76. Compared with the healthy group, the DR group had smaller vessel angles (33.68±3.01 vs 37.78±1.60), smaller fractal dimension (Df) values (1.33±0.05 vs 1.41±0.03), less vessel density (1.12±0.44 vs 2.09±0.36) and fewer vascular branches (206.1±88.8 vs 396.5±91.3), all P<0.001. As the severity of DR increased, Df values decreased, P=0.031. No significant difference between the DME and non-DME groups were observed in vascular morphological characteristics. CONCLUSION: In this study, an artificial intelligence retinal vessel segmentation system is used with 99% accuracy, thus providing with relatively satisfactory performance in the evaluation of quantitative vascular morphology. DR patients have a tendency of vascular occlusion and dropout. The presence of DME does not compromise the integral retinal vascular pattern.

Baicalin protects mice against Salmonella typhimurium infection via the modulation of both bacterial virulence and host response.

BACKGROUND: The worsening problems of antibiotic resistance prompt the need for alternative strategies. Baicalin, which is isolated from Scutellaria baicalensisi, has been demonstrated to exhibit anti-inflammatory, anti-virulence and antimicrobial effects. Salmonella typhimurium is an important foodborne pathogenic bacteriaum that causes gastrointestinal disease in humans and many animals. PURPOSE: The aim of this study was to investigate the effects of baicalin on S. typhimurium infection in mice and its possible mechanism in vitro. STUDY DESIGN: To evaluate the effect of baicalin in vivo, mice were orally administered of baicalin, and then were infected by an intragastric administration of S. typhimurium. The minimal inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of baicalin, baicalein, and oroxylin A against S. typhimurium were detected under the guides of the Clinical and Laboratory Standards Institute. In vitro, Caco-2 cells were infected with S. typhimurium in the presence or absence of baicalin, baicalein, and oroxylin A at sub-MICs. METHODS: In the in vivo experiment, the body weight loss, the serum levels of TNFα,  IL-6, and lactic dehydrogenase (LDH), the pathological changes of the caecum and the caecum bacterial burdens were examined. The MICs and MBCs of baicalin, baicalein, and oroxylin A against S. typhimurium were detected by two-fold serial dilutions. In vitro, Caco-2 cells were infected with S. typhimurium, and the invasion capacity, TNFα, nitrate, and LDH were analysed. The transcription levels of Salmonella pathogenicity island 1 virulence associated genes (sopB, sopE, sopE2) of S. typhimurium in the presence of baicalin, baicalein, and oroxylin A were detected by qRT-PCR. RESULTS: Our results showed that baicalin significantly decreased the body weight loss, the serum levels of TNFα,  IL-6, and LDH, and the caecum bacterial burdens of mice challenged with S. typhimurium. Histological examination showed that baicalin decreased the lesion in the caecum of S. typhimurium-infected mice. MICs and MBCs of baicalin, and oroxylin A. against S. typhimurium were > 128 µg/ml. MICs and MBCs of baicalein against S. typhimurium were 64 µg/ml, and > 128 µg/ml, respectively. Pretreatment of Caco-2 cells or S. typhimurium with baicalin, baicalein, and oroxylin A significantly inhibited the invasion of Caco-2 cells by S. typhimurium in a dose-dependent manner. Sub-MICs of baicalin, baicalein, and oroxylin A also significantly decreased the levels of TNFα, nitrate, and LDH from S. typhimurium-infected Caco-2 cells. Moreover, the transcription levels of sopB, sopE, and sopE2 were significantly suppressed by baicalin, baicalein, and oroxylin A. CONCLUSIONS: These results demonstrated that baicalin is a promising agent for the prevention of S. typhimurium infection via the modulation of both bacterial virulence and host response.