Search

A metal-free construction of highly diastereoselective nine-membered heterocycles is described via the cycloaddition and rearrangement of N-vinyl-α,β-unsaturated ketonitrones and isocyanates. Notably, the prepared nine-membered heterocycles afforded 2,3-dihydropyrrolizines under heating conditions. Mechanistic studies showed that the nine-membered rings might undergo decarboxylation, isomerization, aza-Michael addition, and aromatization to afford 2,3-dihydropyrrolizines in a one-pot reaction.

Cardiac arrest-induced global cerebral ischemia is a main cause of neurological dysfunction in emergency medicine. Transplantation with bone marrow mesenchymal stem cells (MSCs) has been used in stroke models to repair the ischemic brain injury, but it is little studied in models with global cerebral ischemia. In the present study, a hypoxia precondition was used to improve the efficacy of MSC transplantation, given the low survival and migration rates and limited differentiation capacities of MSCs. We found that hypoxia can increase the expansion and migration of MSCs by activating the PI3K/AKT and hypoxia-inducible factor-1α/CXC chemokine receptor-4 pathways. By using a cardiac arrest-induced global cerebral ischemic model in rats, we found that transplantation of hypoxia-preconditioned MSCs promoted the migration and integration of MSCs and decreased neuronal death and inflammation in the ischemic cortex. © 2017 Wiley Periodicals, Inc.

Objective To evaluate the peri-operative, functional and oncological outcomes of robot-assisted partial nephrectomy (RAPN) and laparoscopic partial nephrectomy (LPN) for moderately or highly complex tumours (defined as RENAL nephrometry score ≥7). Patients and Methods We retrospectively analysed the medical charts of 216 patients with complex tumours who underwent LPN (n = 135) or RAPN (n = 81) between 2008 and 2014. Peri-operative data, pathological variables, complications, functional and oncological outcomes were reviewed. Results Demographic characteristics were similar in the two groups. LPN was associated with a longer operating time (149.6 vs 135.6 min; P = 0.017) and greater estimated blood loss (220.8 vs 196.5 mL; P = 0.013). RAPN was associated with a higher direct cost. There were no differences in warm ischaemia time, transfusion rate, conversion rate, hospital stay, operative complications and estimated glomerular filtration rate change at 6 months after surgery. The mean follow-ups for LPN and RAPN were 31.4 and 16.5 months, respectively. The 3-year recurrence-free survival rate was 95.2% for LPN and 97.1% for RAPN (P = 0.71). Conclusion In patients with complex tumours, RAPN and LPN provided acceptable and similar results in terms of peri-operative, functional and oncological outcomes. RAPN was superior to LPN in terms of estimated blood loss and operating time, and LPN was the more cost-effective approach. Both surgery techniques remain viable options in the management of complex tumours with RENAL scores ≥7.

Significant correlations between concentrations of PBDEs and heavy metals were observed in the human body. However, there is a lack of evidence on the linkage between the uptake of heavy metals and PBDEs. This study is the first report on the BDE-47 uptake profile in a human cell line. Hg and As exposures to KERTr (human skin derived keratinocyte) did not significantly (p > 0.05) affect the uptake of BDE47, whereas Pb and Cd significantly (p < 0.05) affected the uptake of BDE-47 in KERTr. The change in Km was minor after exposure to all heavy metals. The maximum transport rate (Vmax) after exposure to Pb (Vmax: 5.23 ± 0.49) and As (Vmax: 4.95 ± 0.60) was significantly increased when compared with the background of the KERTr cell line (Vmax: 4.07 ± 0.35). Real-time RT-PCR indicated that OATP-B, OATP-D, and OATP-E were expressed in the KERTr cell line. The upregulation or downregulation of OATP B and D genes were minor after exposure to heavy metals, but the OATP E gene was upregulated by three to fourfold in KERTr cell line after exposure to Pb an Cd, which may explain the significant increase of uptake of BDE-47 in KERTr after exposures to Pb and Cd. This study indicated that the uptake effects should be considered when performing risk assessment of human exposure to PBDEs and heavy metal. © 2013 Wiley Periodicals, Inc. Environ Toxicol 29: 354–361, 2014.

The resonance Raman spectroscopy in conjunction with the density functional theory calculations were used to study the excited state structural dynamics of 2-mercapto-1-methylimidazole (MMI). The experimental UV absorption bands were assigned according to the time-dependent density functional calculations. The vibrational assignments were done for the A-band resonance Raman spectra of MMI in water and acetonitrile on the basis of the Fourier transform infrared (FT-IR) and FT-Raman measurements in solid, in water and in acetonitrile and the corresponding B3LYP/6-311+G(d, p) computations. The dynamic structures of MMI were obtained by analysis of the resonance Raman intensity pattern and normal mode analysis. The differences in the dynamic structures of MMI and thiourea were revealed and explained. The structural dynamic of MMI was found to be similar to that of 2-thiopyrimidone in terms of major reaction coordinates and thus favored the intra-molecular proton transfer reaction. Copyright © 2012 John Wiley & Sons, Ltd.

Two types of chiral analytes, the urea and amide derivatives of cc-phenylethylamine, were prepared. The effect of intermolecular hydrogen-bonding interaction on self-discrimination of the enantiomers of analytes has been investigated using high-resolution (1)H NMR. It was found that the urea derivatives with double-hydrogen-bonding interaction exhibit not only the stronger hydrogen-bonding interaction but also better self-recognition abilities than the amide derivatives (except for one bearing two NO(2) groups). The present results suggest that double-hydrogen-bonding interaction promotes the self-discrimination ability of the chiral compounds. Copyright (C) 2009 John Wiley & Sons, Ltd.

Taking the North China block as the demonstration zone of “Images of the Earth's Crust & Upper Mantle (IGCP Project 474)”, we calculated the average velocity and thickness of the upper, middle, and lower crust in Beijing-Tianjin-Tangshan (BTT) and adjacent areas by integrating crustal velocity structure from eight wideangle reflection seismic profiles in this region. Using Kriging interpolating technique, the authors have constructed many significant images such as average velocity, thickness and spatial variation of the bottom boundary depths of upper crust, mid-crust and lower crust. These images show that uplift and depression spreading along nearly EW and NE directions dominate in the study region. Faulted-swells and faulted- depressions controlled by NE faults are present too. The formation of geological structure is closely related to tectonic movement that occurred since the Mesozoic in the study region. The authors inferred that there were at least three stages of intense tectonic movements in the Mesozoic and Cenozoic in the study region. Combining with regional tectonic researches, the authors conclude that the nearly EW uplifts and depressions formed in the Triassic and the NE-trending uplifts and depressions formed in the Jurassic. The faulted-uplifts and faulted depressions controlled by NE faults emerged in the Cretaceous. Because the middle crust is a low-velocity layer and its deformation is mainly ductile, which is completely different from the upper and lower crust, it is thickened and has low velocity in uplifted areas, whereas its thickness decreased and has high velocity in depressions. The overall strength of the crust is reduced in places of thick middle crust, where faulting and deformation are easy to occur in later tectonic movements, thus affecting the occurrence of present earthquakes in the study region.

The interspecies somatic cell nuclear transfer (iSCNT) technique for therapeutic cloning gives great promise for treatment of many human diseases. However, the incomplete nuclear reprogramming and the low blastocyst rate of iSCNT are still big problems. Herein, we observed the effect of TSA on the development of rabbit-rabbit intraspecies and rabbit-human interspecies cloned embryos. After treatment with TSA for 6 hr during activation, we found that the blastocyst rate of rabbit-rabbit cloned embryos was more than two times higher than that of untreated embryos; however, the blastocyst rate of TSA-treated rabbit-human interspecies cloned embryos decreased. We also found evident time-dependent histone deacetylation-reacetylation changes in rabbit-rabbit cloned embryos, but not in rabbit-human cloned embryos from fusion to 6 hr after activation. Our results suggest that TSA-treatment does not improve blastocyst development of rabbit-human iSCNT embryos and that abnormal histone deacetylation-reacetylation changes in iSCNT embryos may account for their poor blastocyst development.

Both enantiomers of 2-benzyl-5-bromo-4-oxopentanoic acid were prepared utilizing the diazo ketones as the key intermediates. The compounds were assayed for inhibitory activity against carboxypeptidase A (CPA, EC 3.4.17.1). The (R)-form is 260-fold more potent than the corresponding (S)-form. The finding that (R)-form, which belongs to the L-series, is mostly responsible for the inhibitory activity accords with the substrate specificity of CPA. For comparison, both the optical forms of 2-benzyl-4-oxopentanoic acid were also synthesized and evaluated as the inhibitors against CPA. These results reveal that the introduction of a bromo group at the α-position of ketones can significantly enhance the electrophilicity of the carbonyl group. Further molecular docking study suggested that the gem-diol form of the α-bromo ketone, which mimics the transition state in the CPA catalytic process, could chelate the zinc ion in the active site of CPA and thus result in the strong inhibition.

Vermistatin (=(3R)-4,6-dimethoxy-3-{4-oxo-6-[(1E)-prop-1-en-1-yl]-4H-pyran-3-yl}-2-benzofuran-1(3H)-one; 1) and two new vermistatin derivatives, compounds 2 and 3, were isolated from the fungal strain Guignardia sp. No. 4382 obtained from the South-China Sea. Their structures were elucidated by various methods, including circular dichroism (CD), 1D- and 2D-NMR, and HR-EI-MS. The structures of 1 and 2 were unequivocally corroborated by X-ray crystallography, and their absolute configurations were derived by CD spectroscopy based on a literature comparison. The in vitro cytotoxic and antifungal activities of 1 and 2 were tested.

In order to understand the relationship between earthquake occurrence and crustal heterogeneities, we used 107401 P- and 19624 S-wave high-quality arrival times from the 1992 Landers aftershocks and other local earthquakes which were recorded by both permanent and temporary stations in Southern California to determine detailed three-dimensional P- and S-wave velocity and Poisson's ratio structures beneath the Landers earthquake area. Our results show a correlation between the seismic rupture zones and crustal heterogeneities. The distribution of the Landers aftershocks is cluster-like and separated or terminated in the area where lowvelocity anomalies exist. Most of the large earthquakes with magnitudes bigger than 4 occur in or around areas with high P-wave velocity. The possibility is that high-velocity areas are probably brittle and strong parts which can sustain seismogenic stress, and so can generate earthquakes. In contrast, low-velocity areas may have either higher degree of fracture, high fluid pressure, or higher temperatures where deformation is more likely to be aseismic. In addition, we infer that fluids exist in the Landers earthquake area from the distribution of P- and S-wave velocity and Poisson's ratio. The existence of fluids may weaken the surrounding crustal rocks, then trigger strong earthquakes.

A high-density linkage map was constructed for an F2 population derived from an interspecific cross of cultivated allotetraploid species between Gossypium hirsutum L. and G. barbadense L. A total of 186 F2 individuals from the interspecific cross of "CRI 36 × Hai 7124" were genotyped at 1 252 polymorphic loci including a novel marker system, target region amplification polymorphism (TRAP). The map consists of 1 097 markers, including 697 simple se- quence repeats (SSRs), 171 TRAPs, 129 sequence-related amplified polymorphisms, 98 amplified fragment length polymorphisms, and two morphological markers, and spanned 4 536.7 cM with an average genetic distance of 4.1 cM per marker. Using 45 duplicated SSR loci among chromosomes, 11 of the 13 pairs of homologous chromosomes were identified in tetraploid cotton. This map will provide an essential resource for high resolution mapping of quantitative trait loci and molecular breeding in cotton.

In this work conductive composites consisting of carbon black (CB) and poly(ethylene oxide) were prepared by solution mixing. The composites' resistance drastically changes in organic vapors so that the composites can be used as candidates for gas-sensing materials. Owing to the different conduction mechanisms and solvent/composites interactions, the electrical response behaviors of the composites exhibit specific dependences on CB content and environmental temperature, which were only reported previously in a few instances. In addition, the rate of response was also correlated with solvent polarity, solubility, etc. The findings would help to understand the micromechanism of response of the composites and to improve the sensing performance as well. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1517–1523, 2005

The communication reports a way to prepare carbon black (CB)/waterborne polyurethane conducting composites with percolation thresholds as low as 0.2 vol.-% through conventional latex blending. CB particles in the composites appear segregated in their distribution and are located in the two-dimensional interstices among the polymer domains. The intimate filler/matrix interaction also improves the tensile strength of the matrix at the CB content corresponding to the electrical percolation threshold

Liver cancer is a major global health problem being the sixth most common cancer and the third cause of cancer-related death, with hepatocellular carcinoma (HCC) representing more than 90% of primary liver cancers. Mounting evidence suggests that, compared with their normal counterparts, many types of cancer cell have increased levels of ROS. Therefore, cancer cells need to combat high levels of ROS, especially at early stages of tumor development. Recent studies have revealed that ROS-mediated regulation of redox-sensitive proteins (redox sensors) is involved in the pathogenesis and/or progression of many human diseases, including cancer. Unraveling the altered functions of redox sensors and the underlying mechanisms in hepatocarcinogenesis is critical for the development of novel cancer therapeutics. For this reason, redox proteomics has been developed for the high-throughput screening of redox sensors, which will benefit the development of novel therapeutic strategies for the treatment of HCC. In this review, we will briefly introduce several novel redox proteomics techniques that are currently available to study various oxidative modifications in hepatocarcinogenesis and summarize the most important discoveries in the study of redox processes related to the development and progression of HCC.

A composite finite volume method (FVM) is developed on unstructured triangular meshes and tested for the two-dimensional free-surface flow equations. The methodology is based on the theory of the remainder effect of finite difference schemes and the property that the numerical dissipation and dispersion of the schemes are compensated by each other in a composite scheme. The composite FVM is formed by global composition of several Lax–Wendroff-type steps followed by a diffusive Lax–Friedrich-type step, which filters out the oscillations around shocks typical for the Lax–Wendroff scheme. To test the efficiency and reliability of the present method, five typical problems of discontinuous solutions of two-dimensional shallow water are solved. The numerical results show that the proposed method, which needs no use of a limiter function, is easy to implement, is accurate, robust and is highly stable. Copyright © 2001 John Wiley & Sons, Ltd.

If a real signal can be written in the form u(t) = a(t) cos θ(t), we call a(t), θ(t) and graphic the instantaneous amplitude, phase and frequency of u(t), respectively. In many practical fields, the extraction of such instantaneous parameters as instantaneous amplitude, phase and frequency, is quite important. However, the existing methods for calculation of instantaneous parameters have some defects. In this paper, we construct a kind of wavelet, which has compact support in the frequency domain, and the Fourier transform of the wavelet has analytic expression. Using these wavelets, we obtain a fast, local and de-noising algorithm for calculation of instantaneous parameters of signal. Theoretical analysis and numerical simulations show that our method is practical and efficient. It is believed that this method can meet the needs of many practical fields.