Theoretical Kinetics of Radical-Radical Reaction NH2NH + NH2 and Its Implications for Monomethylhydrazine Pyrolysis Mechanism.

Significant discrepancies were observed between the experiments and the simulations for NH2 time-histories in monomethylhydrazine pyrolysis with the robust mechanism proposed by Pascal and Catoire. The rate of formation analyses for NH2 indicated the significance of the reaction NH2NH + NH2 = H2NN + NH3, which has not been well-defined. In this study, ab initio calculations were performed for the theoretical description of the NH2NH + NH2 chemistry. Most stationary points on the potential energy surface were quantified at the CCSD(T)/CBS//M06-2X/aug-cc-pVTZ level, and the multireference methods were employed for barrier-less reaction and some transition states. The temperature- and pressure-dependent rate coefficients were determined using classical and microcanonical variational transition state theories. Four primary reaction channels were identified as competitive: 1) The H atom abstraction reaction yielding N2H2(T) + NH3, dominating at 1350-3000 K across the 0.001-100 atm pressure range. 2) The H atom abstraction reaction forming N2H2(S) + NH3, dominating at 800-1350 K and competing with the processes of chemical activation and collisional stabilization below 800 K. 3) The chemical-activated reaction resulting in H2NN(S) + NH3, dominating below 800 K at 0.001 atm. 4) The collisional-stabilized recombination reaction leading to N3H5, becoming significant as pressure increases and dominating below 600 and 650 K at 1 and 100 atm, respectively. The implications of newly calculated NH2NH + NH2 kinetics for the monomethylhydrazine pyrolysis mechanism were evaluated, and updates were implemented. Sensitivity analyses indicated the necessity of additional research efforts to comprehend the dynamics of CH3NH2 unimolecular and N2H2 + NH2 reaction systems. The rate coefficients presented in this study can be employed to develop the chemical kinetic model of nitryl-containing systems.

Open versus laparoscopic Hartmann's procedure: a systematic review and meta-analysis.

PURPOSE: Hartmann's procedure is traditionally performed in emergency situations where single-step procedures with immediate anastomosis may be unsafe. However, it can be associated with significant morbidity and low colostomy reversal rate. Whilst randomised controlled trials and a Cochrane review have reported strong evidence of laparoscopic over open colectomies, no such reviews have been performed for Hartmann's procedure. Hence, this paper aims to summarise the existing evidence to determine the efficacy of laparoscopic Hartmann's procedure over its open counterpart. METHODS: Embase, Medline and Cochrane databases were searched from inception to 15 November 2020 for keywords relating to 'laparoscopy' and 'Hartmann' using strict inclusion and exclusion criteria. Odds ratio was estimated for dichotomous outcomes and weighted mean difference was estimated for continuous outcomes. RESULTS: From the 836 articles yielded from the search strategy, 12 articles were selected for meta-analysis. Pooled analysis revealed that laparoscopic Hartmann's procedure (LHP) allows for a shorter length of stay, and a lower risk of overall surgical site infections and superficial surgical site infections. There was no significant difference in other outcomes. Single-arm analysis of LHP also showed an unprecedented high colostomy reversal rate of over 80%. CONCLUSION: In clinically suitable patients, laparoscopic Hartmann's procedure has benefits over open Hartmann's procedure. Despite the selection bias of single-arm studies, LHP has reported a high stoma reversal rate of over 80%. Future well-controlled studies should be done to affirm the findings.

A Theoretical Study of H-Abstractions of Benzaldehyde by H, O3(P), 3O2, OH, HO2, and CH3 Radicals: Ab Initio Rate Coefficients and Their Uncertainty Quantification.

Benzaldehyde is a vital intermediate during the oxidation of toluene and oxygenated aromatics, but benzaldehyde's combustion chemistry currently gains little attention. The H-atom abstraction of benzaldehyde is one critical reaction class, yet its rate coefficients rely on the analogy of molecular similarity. For this reason, we have employed the ab initio calculations at the CCSD(T)/cc-pVTZ//M06-2X/6-311+g(d,p) level of theory, along with the RRKM master equation to predict the rate coefficients of H-abstraction reactions of benzaldehyde by H, O3(P), 3O2, OH, HO2, and CH3 radicals. The calculated rate coefficients of benzaldehyde + OH generally agree with literature measurements. From the branching ratio analysis, all the H-abstractions from ring sites can be neglected in kinetic model construction except by OH radical at temperature above 1700 K, where the ring sites contribute a relatively large branching ratio to consume benzaldehyde. A random sampling method has been used to estimate the global uncertainty in the calculated rate coefficients. The logarithm of uncertainty is proportional to the reciprocal temperature, and the global uncertainty is primarily derived from the energy errors and is almost independent of the attacking species. Comparison between benzaldehyde and acetaldehyde reveals that their rate coefficients are consistent only in H-abstractions by H and HO2 but are conflictive in other reactions, especially in the case of OH. By incorporating the new calculations, existing models show a faster prediction in autoignition delay times of benzaldehyde. This study reports the first high-level ab initio calculations for the H-atom abstraction reaction class of benzaldehyde. It is necessary for the future comprehensive kinetic modeling of aromatic aldehyde.

Subwavelength grating based mode (de)multiplexer for 3D photonic integrated circuits.

A broadband three-dimensional (3D) mode (de) multiplexer [(De)MUX] is proposed based on the subwavelength grating (SWG) for 3D photonic integrated circuits (PICs). The proposed 3D mode (De)MUX consists of three SWG waveguides on two vertical layers. The coupling strength and operating bandwidth can be increased benefitting from both the subwavelength structure and offset between bus and access SWGs. The proposed 3D mode (De)MUX is optimized based on the 3D full-vectorial finite difference time domain method. The 1-dB bandwidths of the optimized device are over >300, 107, and 128 nm for demultiplexing TE0, TE1, and TE2 modes, respectively. The coupling lengths are only 5.0 and 1.75 µm for demultiplexing the TE1 and TE2 modes, respectively. The insertion losses are 0.12, 0.27, and 0.29 dB, respectively. The proposed 3D mode (De)MUX is also fabrication tolerant.

A Systematic Theoretical Kinetics Analysis for the Waddington Mechanism in the Low-Temperature Oxidation of Butene and Butanol Isomers.

The Waddington mechanism, or the Waddington-type reaction pathway, is crucial for low-temperature oxidation of both alkenes and alcohols. In this study, the Waddington mechanism in the oxidation chemistry of butene and butanol isomers was systematically investigated. Fundamental quantum chemical calculations were conducted for the rate constants and thermodynamic properties of the reactions and species in this mechanism. Calculations were performed using two different ab initio solvers: Gaussian 09 and Orca 4.0.0, and two different kinetic solvers: PAPR and MultiWell, comprehensively. Temperature- and pressure-dependent rate constants were performed based on the transition state theory, associated with the Rice Ramsperger Kassel Marcus and master equation theories. Temperature-dependent thermochemistry (enthalpies of formation, entropy, and heat capacity) of all major species was also conducted, based on the statistical thermodynamics. Of the two types of reaction, dissociation reactions were significantly faster than isomerization reactions, while the rate constants of both reactions converged toward higher temperatures. In comparison, between two ab initio solvers, the barrier height difference among all isomerization and dissociation reactions was about 2 and 0.5 kcal/mol, respectively, resulting in less than 50%, and a factor of 2-10 differences for the predicted rate coefficients of the two reaction types, respectively. Comparing the two kinetic solvers, the rate constants of the isomerization reactions showed less than a 32% difference, while the rate of one dissociation reaction (P1 ↔ WDT12) exhibited 1-2 orders of magnitude discrepancy. Compared with results from the literature, both reaction rate coefficients (R4 and R5 reaction systems) and species' thermochemistry (all closed shell molecules and open shell radicals R4 and R5) showed good agreement with the corresponding values obtained from the literature. All calculated results can be directly used for the chemical kinetic model development of butene and butanol isomer oxidation.

Chemical Kinetics of H-Atom Abstraction from Ethanol by HȮ2: Implication for Combustion Modeling.

As a renewable source of energy, ethanol has been widely used in internal combustion engines as either a gasoline alternative fuel or a fuel additive. However, as the chemical source term of the computational fluid dynamics simulation of combustors, there remains a disagreement in understanding the chemical kinetic mechanism of ethanol. The reaction mechanism of ethanol + HÈ®2 is a well-known crucial reaction class in terms of predicting the reactivity of ethanol as well as ethylene formation under engine-relevant conditions. However, the kinetic parameters of the reactions are basically extrapolated by analogy to the n-butanol + HÈ®2 system calculated by Zhou et al. (Zhou et al. Int. J. Chem. Kinet. 2012, 44 (3), 155-164). The reliability of such an analogy remains to be seen because no direct theoretical or experimental evidence is available in the literature to date. In this study, thermal rate coefficients of H-atom abstraction reactions for the ethanol + HÈ®2 system were determined by using both conventional transition-state theory and canonical variational transition-state theory, with the potential energy surface evaluated at the CCSD(T)/cc-pVTZ//M06-2x/def-TZVP level. The quantum-mechanical effects were corrected by the zero-curvature tunneling method at low temperatures (<750 K), and difference schemes of two Eckart functions were fitted to optimize the minimum energy path curves. Torsional modes of the -CH3 and -OH groups were treated by using the hindered-internal-rotation approximation. Furthermore, the rate coefficients of the title reaction were calculated at both the CCSD(T)/cc-pVTZ//M06-2x/def-TZVP and CCSD(T)/CBS//M06-2x/def-TZVP levels of theory with uncertainty of a factor of 3. Similar to the n-butanol + HÈ®2 system, the title system is dominated by α-site H-atom abstraction, but the rate coefficients of the three channels are slightly slower than that of the n-butanol + HÈ®2 system. In general, the new calculations show only a limited effect on the ethanol reactivity at low pressures and high temperatures (>1300 K), but they prevent the kinetic mechanisms from overpredicting ignition delay times under engine-relevant conditions.

Kinetics of Hydrogen Abstraction and Addition Reactions of 3-Hexene by ȮH Radicals.

Rate coefficients of H atom abstraction and H atom addition reactions of 3-hexene by the hydroxyl radicals were determined using both conventional transition-state theory and canonical variational transition-state theory, with the potential energy surface (PES) evaluated at the CCSD(T)/CBS//BHandHLYP/6-311G(d,p) level and quantum mechanical effect corrected by the compounded methods including one-dimensional Wigner method, multidimensional zero-curvature tunneling method, and small-curvature tunneling method. Results reveal that accounting for approximate 70% of the overall H atom abstractions occur in the allylic site via both direct and indirect channels. The indirect channel containing two van der Waals prereactive complexes exhibits two times larger rate coefficient relative to the direct one. The OH addition reaction also contains two van der Waals complexes, and its submerged barrier results in a negative temperature coefficient behavior at low temperatures. In contrast, The OH addition pathway dominates only at temperatures below 450 K whereas the H atom abstraction reactions dominate overwhelmingly at temperature over 1000 K. All of the rate coefficients calculated with an uncertainty of a factor of 5 were fitted in a quasi-Arrhenius formula. Analyses on the PES, minimum reaction path and activation free Gibbs energy were also performed in this study.

Clinical analysis: 13 cases of pregnancy complicated with Takayasu arteritis.

OBJECTIVES: To investigate the clinical features, disposition, and effect of pregnancy complicated with Takayasu arteritis (P-TA) on maternal and fetal outcomes. MATERIAL AND METHODS: The clinical data (diagnosis and treatment, peri-pregnancy monitoring, and pregnancy outcomes) of patients with P-TA treated in our hospital between September 2007 and April 2016 were analyzed retrospectively. RESULTS: Among the 13 P-TA cases, seven were diagnosed before pregnancy, and six were diagnosed during pregnancy; six cases were diagnosed as the generalized type, and seven cases were diagnosed as the cephalic-brachial type; six cases were in the stable stage, and seven cases were in the active stage. All the cases in the active stage underwent glucocorticoid therapy. Four cases developed complications, including cardiac dysfunction combined with preeclampsia in two cases, preeclampsia in one case, and stroke in one case. Eleven patients successfully delivered (nine cases of full-term delivery and two cases of premature delivery); one patient had late miscarriage; one patient had missed abortion. All the parturients survived and delivered 11 neonates (nine full-term neonates and two premature neonates) and one low-birth-weight neonate; no neonatal asphyxia or death occurred. CONCLUSIONS: Patients with P-TA can have better maternal and child outcomes through timely diagnosis and treatment, dynamic monitoring, or timely pregnancy termination.

Identification of resident progenitors labeled with Top2a responsible for proximal tubular regeneration in ischemia reperfusion-induced acute kidney injury.

BACKGROUND: Acute kidney injury is a common fatal disease with complex etiology and limited treatment methods. Proximal tubules (PTs) are the most vulnerable segment. Not only in injured kidneys but also in normal kidneys, shedding of PTs often happens. However, the source cells and mechanism of their regeneration remain unclear. METHODS: ScRNA and snRNA sequencing data of acute injured or normal kidney were downloaded from GEO database to identify the candidate biomarker of progenitor of proximal tubules. SLICE algorithm and CytoTRACE analyses were employed to evaluate the stemness of progenitors. Then the repairing trajectory was constructed through pseudotime analyses. SCENIC algorithm was used to detect cell-type-specific regulon. With spatial transcriptome data, the location of progenitors was simulated. Neonatal/ adult/ aged mice and preconditioning AKI mice model and deconvolution of 2 RNA-seq data were employed for validation. RESULTS: Through cluster identification, PT cluster expressed Top2a specifically was identified to increase significantly during AKI. With relatively strong stemness, the Top2a-labeled PT cluster tended to be the origin of the repairing trajectory. Moreover, the cluster was regulated by Pbx3-based regulon and possessed great segmental heterogeneity. Changes of Top2a between neonatal and aged mice and among AKI models validated the progenitor role of Top2a-labeled cluster. CONCLUSIONS: Our study provided transcriptomic evidence that resident proximal tubular progenitors labeled with Top2a participated in regeneration. Considering the segmental heterogeneity, we find that there is a group of reserve progenitor cells in each tubular segment. When AKI occurs, the reserve progenitors of each tubular segment proliferate and replenish first, and PT-progenitors, a cluster with no obvious PT markers replenish each subpopulation of the reserve cells.

Stability evaluation of gardenia yellow pigment in the presence of different antioxidants or microencapsulating agents.

The chemical instability of gardenia yellow pigment (GYP) limits its utilization in the food industry. In this study, the effects of different antioxidants (0.2% of tea polyphenols, sodium phytate, potassium citrate, and ascorbic acid) and microencapsulating agents (gum Arabic, maltodextrin, inulin, and gum Arabic/maltodextrin) on the degradation of GYP under different conditions (heat, light, and ferric iron) were evaluated. Then, the characteristic properties of microcapsules coated with gum Arabic/maltodextrin, gum Arabic/maltodextrin/tea polyphenols, maltodextrin, and maltodextrin/tea polyphenols were investigated. Furthermore, food models were simulated to evaluate the GYP stability of the microcapsules. The results showed that tea polyphenols, maltodextrin, and gum Arabic/maltodextrin significantly improved the GYP stability. Moreover, the presence of GYP in microcapsules was confirmed by nuclear magnetic resonance and Fourier transform infrared spectroscopy. In addition, GYP-MD/TP possessed high thermal stability under different cooking methods. PRACTICAL APPLICATION: Gardenia yellow pigment (GYP) is easily degraded under light and high-temperature conditions, which limits its applications in the food industry. This study will provide effective clues for expanding the practical applications of GYP in the natural pigment industry.

Metabolic analysis of the regulatory mechanism of sugars on secondary flowering in Magnolia.

BACKGROUND: Magnolia, a traditional and important ornamental plant in urban greening, has been cultivated for about 2000 years in China for its elegant flower shape and gorgeous flower color. Most varieties of Magnolia bloom once a year in spring, whereas a few others, such as Magnolia liliiflora Desr. 'Hongyuanbao', also bloom for the second time in summer or early autumn. Such a twice flowering trait is desirable for its high ornamental value, while its underlying mechanism remains unclear. METHODS: Paraffin section was used to show the flowering time and phenotypic changes of M. liliiflora 'Hongyuanbao' during the twice flowering periods from March 28 to August 25, 2018. Gas chromatography-mass spectrometry (GC-MS) was then performed to explore the chemical metabolites through the twice flower bud differentiation process in 'Hongyuanbao', and the metabolites were screened and identified by orthogonal projection to latent structures discriminant analysis (OPLS-DA). Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis (KEGG) was used to reveal the relationship between the sugar metabolites and twice-flowering characteristic. To further investigate the potential role of sucrose and trehalose on flowering regulation of 'Hongyuanbao', the plants once finished the spring flowering were regularly sprayed with sucrose and trehalose solutions at 30 mM, 60 mM, and 90 mM concentrations from April 22, 2019. The flower bud differentiation processes of sprayed plants were observed and the expression patterns of the genes involved in sucrose and trehalose metabolic pathways were studied by quantitative reverse transcription PCR (qRT-PCR). RESULTS: It showed that 'Hongyuanbao' could complete flower bud differentiation twice in a year and flowered in both spring and summer. The metabolites of flower bud differentiation had a significant variation between the first and second flower buds. Compared to the first flower bud differentiation process, the metabolites in the sucrose and trehalose metabolic pathways were significantly up-regulated during the second flower bud differentiation process. Besides that, the expression levels of a number of trehalose-6-phosphate synthase (TPS) genes including MlTPS1, MlTPS5, MlTPS6, MlTPS7 and MlTPS9 were substantially increased in the second flower differentiation process compared with the first process. Exogenous treatments indicated that compared to the control plants (sprayed with water, CK), all three concentrations of trehalose could accelerate flowering and the effect of 60 mM concentration was the most significant. For the sucrose foliar spray, only the 60 mM concentration accelerated flowering compared with CK. It suggested that different concentration of trehalose and sucrose might have different effects. Expression analysis showed that sucrose treatment increased the transcription levels of MlTPS5 and MlTPS6, whereas trehalose treatment increased MlTPS1, showing that different MlTPS genes took part in sucrose and trehalose metabolic pathways respectively. The expression levels of a number of flowering-related genes, such as MlFT, MlLFY, and MlSPL were also increased in response to the sprays of sucrose and trehalose. CONCLUSIONS: We provide a novel insight into the effect of sucrose and trehalose on the flowering process in Magnolia. Under the different sugar contents treatments, the time of flower bud differentiation of Magnolia was advanced. Induced and accelerated flowering in response to sucrose and trehalose foliar spray, coupled with elevated expression of trehalose regulatory and response genes, suggests that secondary flower bud formation is a promoted by altered endogenous sucrose and trehalose levels. Those results give a new understanding of sucrose and trehalose on twice-flowering in Magnolia and provide a preliminary speculation for inducing and accelerating the flowering process in Magnolia.

Identification of a small molecule SIRT2 inhibitor with selective tumor cytotoxicity.

As a member of the class III histone deacetylases, Sirtuin-2 (SIRT2) is critical in cell cycle regulation which makes it a potential target for cancer therapeutics. In this study, we identified a novel SIRT2 inhibitor, AC-93253, with IC(50) of 6 microM in vitro. The compound is selective, inhibiting SIRT2 7.5- and 4-fold more potently than the closely related SIRT1 and SIRT3, respectively. AC-93253 significantly enhanced acetylation of tubulin, p53, and histone H4, confirming SIRT2 and SIRT1 as its cellular targets. AC-93253 as a single agent exhibited submicromolar selective cytotoxicity towards all four tumor cell lines tested with a therapeutic window up to 200-fold, comparing to any of the three normal cell types tested. Results from high content analysis suggested that AC-93253 significantly triggered apoptosis. Taken together, SIRT2 selective inhibitor AC-93253 may serve as a novel chemical scaffold for structure-activity relationship study and future lead development.

Development of Arg-Based Biodegradable Poly(ester urea) Urethanes and Its Biomedical Application for Bone Repair.

Thermal plastic polyurethanes (TPUs), serving as biomaterials, have become increasingly prevalent over time in many fields including artificial blood vessels, pericardial patches and other tissue engineering scaffolds by virtue of well adjustable performance. However, synthetic polyurethanes are, to some extent, inadequate for their cytocompatibility and biological activity owing to high hydrophobicity and lack of active groups. In this study, an amino-terminated bis(L-arginine) alkylene diester extender (L-Arg-8) was synthesized and Arg-based biodegradable poly(ester urea) urethanes (PEUUs) with different content of arginine groups were designed, synthesized and characterized in regard to the amelioration of the biodegradability, hydrophilicity and cytocompatibility of thermoplastic polyurethanes (TPUs) with PCL as soft segments. Biodegradability, hydrophilicity and positive surface charges increased after Arginine was introduced. As cytocompatibility was improved, PEUU materials A8-1.2 and A8-1.6 were proved to be suitable for human dental pulp stem cells (hDPSCs) to adhere, grow and proliferate on in vitro. These materials would unlock great potential for the use in tissue engineering and regeneration. Additionally, halloysite nanotubes (HNTs) were composited to PEUUs for further exploration to the applications in bone tissue. The addition of halloysite nanotubes further stimulated the osteogenic differentiation of human dental pulp stem cells in vitro. At the same time, a rat cranial defect model was built to assess effects of repair in vivo. Osteointegration and repair were promoted by patch-implanted groups. A8-1.2 6% HNTs showed the best repair. All the results indicated that Arg-based poly(ester urea) urethanes and the composites were conductive to bone repair.

A chemical biology screen identifies a vulnerability of neuroendocrine cancer cells to SQLE inhibition.

Aberrant metabolism of cancer cells is well appreciated, but the identification of cancer subsets with specific metabolic vulnerabilities remains challenging. We conducted a chemical biology screen and identified a subset of neuroendocrine tumors displaying a striking pattern of sensitivity to inhibition of the cholesterol biosynthetic pathway enzyme squalene epoxidase (SQLE). Using a variety of orthogonal approaches, we demonstrate that sensitivity to SQLE inhibition results not from cholesterol biosynthesis pathway inhibition, but rather surprisingly from the specific and toxic accumulation of the SQLE substrate, squalene. These findings highlight SQLE as a potential therapeutic target in a subset of neuroendocrine tumors, particularly small cell lung cancers.

AMP-activated protein kinase is involved in endothelial NO synthase activation in response to shear stress.

OBJECTIVE: The regulation of AMP-activated protein kinase (AMPK) is implicated in vascular biology because AMPK can phosphorylate endothelial NO synthase (eNOS). In this study, we investigate the regulation of the AMPK-eNOS pathway in vascular endothelial cells (ECs) by shear stress and the activation of aortic AMPK in a mouse model with a high level of voluntary running (High-Runner). METHODS AND RESULTS: By using flow channels with cultured ECs, AMPK Thr172 phosphorylation was increased with changes of flow rate or pulsatility. The activity of LKB1, the upstream kinase of AMPK, and the phosphorylation of eNOS at Ser1179 were concomitant with AMPK activation responding to changes in flow rate or pulsatility. The blockage of AMPK by a dominant-negative mutant of AMPK inhibited shear stress-induced eNOS Ser1179 phosphorylation and NO production. Furthermore, aortic AMPK activity and level of eNOS phosphorylation were significantly elevated in the aortas of High-Runner mice. CONCLUSIONS: Our results suggest that shear stress activates AMPK in ECs, which contributes to elevated eNOS activity and subsequent NO production. Hence, AMPK, in addition to serving as an energy sensor, also plays an important role in regulating vascular tone.

Basic Characteristics and Spatial Patterns of Pseudo-Settlements--Taking Dalian as An Example.

A person's living behavior patterns are closely related to three types of settlements: real-life settlements, imagined settlements, and pseudo-settlements. The term "pseudo-settlement" (PS) refers to the places that are selectively recorded and represented after the mass media chose and restructure the residence information. As the mass media rapidly develops and people's way of obtaining information gradually change, PS has already become one of the main ways for people to recognize and understand real-life settlements, as well as describe their impressions of imagined settlements. PS also has a profound impact on tourism, employment, investment, migration, real estate development, etc. Thus, the study of PSs has important theoretical and practical significance. This paper proposes to put forward residential quarters where the mass media is displayed as the object of study and establishes the pseudo-settlement index system of Dalian in and elaborate analysis of the concept of PSs. From three aspects, including pseudo-buildings, pseudo-districts and pseudo-culture, this paper uses the ArcGIS 10.0 kernel density (spacial analyst) to analyze and interpret the basic characteristics and spatial patterns of 14 elements of the PS in Dalian. Through systemic clustering analysis, it identifies eight major types of PSs in Dalian. Then it systematically elaborates current situations and characteristics of the spatial pattern of PSs in Dalian, namely: regionally concentrated, widely scattered and blank spaces without pseudo-settlements. Finally, this paper discusses the mechanism of formation of PSs in Dalian.

Screening Active Compounds from Garcinia Species Native to China Reveals Novel Compounds Targeting the STAT/JAK Signaling Pathway.

Natural compounds from medicinal plants are important resources for drug development. In a panel of human tumor cells, we screened a library of the natural products from Garcinia species which have anticancer potential to identify new potential therapeutic leads and discovered that caged xanthones were highly effective at suppressing multiple cancer cell lines. Their anticancer activities mainly depended on apoptosis pathways. For compounds in sensitive cancer line, their mechanisms of mode of action were evaluated. 33-Hydroxyepigambogic acid and 35-hydroxyepigambogic acid exhibited about 1 µM IC50 values against JAK2/JAK3 kinases and less than 1 µM IC50 values against NCI-H1650 cell which autocrined IL-6. Thus these two compounds provided a new antitumor molecular scaffold. Our report describes 33-hydroxyepigambogic acid and 35-hydroxyepigambogic acid that inhibited NCI-H1650 cell growth by suppressing constitutive STAT3 activation via direct inhibition of JAK kinase activity.

The extrinsic coagulation cascade and tissue factor pathway inhibitor in macrophages: a potential therapeutic opportunity for atherosclerotic thrombosis.

OBJECTIVES: The coagulation protease cascade plays the central requisite role in initiation of arterial atherothrombosis. However, the relative participation of the extrinsic as compared to the intrinsic pathway is incompletely resolved. We have investigated in vivo the relative importance of the extrinsic and intrinsic pathways to define which is more essential to atherothrombosis and therefore the preferable prophylactic therapeutic target. We further addressed which type of plaque associated macrophage population is associated with the thrombotic propensity of atherosclerotic plaques. METHODS: Both photochemical injury and ferric chloride vascular injury models demonstrated arterial thrombosis formation in ApoE deficient mice. We found that direct interference with the extrinsic pathway, but not the intrinsic pathway, markedly diminished the rate of thrombus formation and occlusion of atherosclerotic carotid arteries following experimental challenge. To explore which plaque macrophage subtype may participate in plaque thrombosis in regard to expression tissue factor pathway inhibitor (TFPI), bone marrow derived macrophages of both M and GM phenotypes expressed tissue factor (TF), but the level of TFPI was much greater in M- type macrophages, which exhibited diminished thrombogenic activity, compared to type GM-macrophages. RESULTS AND CONCLUSIONS: Our works support the hypothesis that the TF-initiated and direct extrinsic pathway provides the more significant contribution to arterial plaque thrombogenesis. Activation of the TF driven extrinsic pathway can be influenced by differing colony-stimulating factor influenced macrophage TFPI-1 expression. These results advance our understanding of atherothrombosis and identify potential therapeutic targets associated with the extrinsic pathway and with macrophages populating arterial atherosclerotic plaques.

Identification of inhibitors of HSF1 functional activity by high-content target-based screening.

Cancer cells are known to experience a high level of stress and may require constant repair for survival and proliferation. Recent studies showed that inhibition of heat shock factor 1 (HSF1), the key regulator for the stress-activated transcription of heat shock protein (HSP), can reduce the tumorigenic potential of cancer cells. Such a "nononcogene addiction" phenomenon makes HSF1 an attractive cancer drug target. Here, the authors report an image-based high-content screening (HCS) assay for HSF1 functional inhibitors. A heat shock-based methodology was used to stimulate the stress response followed by quantitative measurement of HSF1/HSP70 granules for compound-induced inhibitory effects. The authors discovered a small molecule from a compound library that inhibits HSF1 granule formation substantially in heat-shocked HeLa cells with IC(50) at 80 nM. Electorphoretic mobility shift of HSF1 by this compound suggested significant inhibition of HSF1 phosphorylation, accompanied by reduced expression levels of HSP70 and HSP90 after heat induction. Importantly, HeLa cells stably transfected with HSF1 shRNA were more resistant to the compound treatment under lethal temperature than cells containing HSF1, further validating an HSF1-dependent mechanism of action. The HCS assay the authors developed was robust with a Z' factor of 0.65 in a 384-well plate format, providing a valuable method for identifying small-molecule functional inhibitors of HSF1 for potential cancer treatment.

Novel chimeric genotype 1b/2a hepatitis C virus suitable for high-throughput screening.

A major obstacle in hepatitis C virus (HCV) research has been the lack of a permissive cell culture system that produces infectious viral particles. Significant breakthroughs have been achieved lately in establishing such culture systems. Yet to date, there are no reports of the applications of any of these systems in HCV drug screening. Here, we report the generation of two monocistronic, chimeric genotype 1 full-length HCV genome molecules. These molecules, C33J-Y835C-UBI and C33J-Y835C-FMDV2A, both contain the structural protein region from genotype 1 (subtype 1b, Con1) and the remaining region from the genotype 2a (JFH1) clone. Both contain the humanized Renilla luciferase reporter gene which is separated from the rest of the HCV open reading frame by two different cleavage sites. The viral RNAs replicated efficiently in transfected cells. Viral particles produced were infectious in naïve Huh7.5 cells, and the infectivity could be blocked by monoclonal antibody against a putative HCV entry cofactor, CD81. A pilot high-throughput screen of 900 unknown compounds was executed by both the genotype 2a subgenomic replicon system and the infectious system. Thirty-one compounds were identified as hits by both systems, whereas 78 compounds were identified as hits only for the infectious system, suggesting that the infectious system is capable of identifying inhibitors targeting the viral structural proteins and steps involving them in the viral life cycle. The infectious HCV system developed here provides a useful and versatile tool which should greatly facilitate the identification of HCV inhibitors currently not identified by the subgenomic replicon system.