Arsenic trioxide-induced apoptosis is independent of stress-responsive signaling pathways but sensitive to inhibition of inducible nitric oxide synthase in HepG2 cells

Arsenic trioxide (As(2)O(3)) has been found to be remarkably effective in the treatment of patients with acute promyelocytic leukemia (APL). Although evidences for the proapoptotic activity of As(2)O(3) have been suggested in leukemic and other solid cancer cells, the nature of intracellular mechanisms is far from clear. In the present study, we investigated As(2)O(3) affect on the stress-responsive signaling pathways and pretreatment with antioxidants using HepG2 cells. When treated with micromolar concentrations of As(2)O(3), HepG2 cells became highly apoptotic paralleled with activation of caspase-3 and members of mitogen-activated protein kinases (MAPKs) including extracellular signal-regulated kinase (ERK) and c-jun NH(2)-terminal kinase (JNK) but not p38 MAP kinase. However, inhibition of each kinase activity failed to inhibit apoptosis by As(2)O(3). Addition of n-acetyl cysteine (NAC) or diphenyleneiodonium (DPI) effectively protected cells from apoptosis and significantly lowered As(2)O(3)-induced activation of caspase-3. However, neither NAC nor DPI was able to effect ERK or JNK activation induced by As(2)O(3). Guanidinoethyldisulfide dihydrochloride (GED) and 2-ethyl-2-thiopseudourea (ETU), known inhibitors of the inducible nitric oxide synthase (iNOS), also suppressed the apoptotic activity of As(2)O(3). These results suggest that As2O3 induces caspase-mediated apoptosis involving a mechanism generating oxidative stress. However, activation of some stress-responsive signaling pathways by As(2)O(3) may not be the major determinant in the course of apoptotic processes.     

有机硅改性丙烯酸酯共聚乳液合成方法及胶膜性能的研究

用一次投料法、单体乳液滴加法和引发剂滴加法有机硅改性丙烯酸酯共聚乳液，聚合过程、胶粒形态及乳液稳定性的观测结果表明：单体乳液滴加法是合成该类乳液的最佳方法，研究了单体乳液滴加法中有机硅含量与聚合反及胶膜性能的关系，结果表明：有机硅含量在１５％以下时，聚合反应可以顺利进行，胶膜性能不仅依赖于聚合时有机硅单体的总量，而且还依赖于有机硅单体中活性硅氧烷所占的比例。     

Encoding method for OBOC small molecule libraries using a biphasic approach for ladder-synthesis of coding tags

In the "one-bead one-compound" (OBOC) combinatorial library method, each compound bead displays only one compound entity. Hundreds of thousands to millions of compound beads can be synthesized rapidly and screened simultaneously. Positive compound beads are then isolated for structural analysis. To fully exploit the power of OBOC combinatorial small molecule libraries, a robust and high throughput encoding method is needed to decode the positive compound beads. In this paper, we report on the development of a novel encoding strategy that combines the concepts of ladder-synthesis and chemical encoding on bilayer beads. In these encoded libraries, small molecule compounds are displayed on the bead surface, and cleavable coding tags consisting of a series of truncated molecules reside in the bead interior. Such a library can be easily constructed using the biphasic approach (J. Am. Chem. Soc.2002, 124, 7678) to topologically segregate the functionalities of the beads during library synthesis. The ladder members and coding tags are then released for MALDI-TOF-MS analysis. To simplify the interpretation of the mass spectra, we purposely add bromine into the cleavable linker so that the cleavage products generate a characteristic isotope fingerprint. The chemical structure of library compounds can be determined by analyzing the mass differences between adjacent peaks on the mass spectra. This encoding strategy also provides valuable information on the quality of the testing compound on the surface of the bead. To validate this methodology, a model OBOC small molecule library with 12,288 members was synthesized on TentaGel beads and screened against streptavidin. The chemical structures of the compound on each positive bead were unambiguously identified.     

Remote substituent effects on bond dissociation energies of para-substituted aromatic silanes

UB3LYP/6-31G(d) and ROMP2/6-311++G(d,2p) methods were used to calculate the Si-X bond dissociation energies (BDEs) of a number of para-substituted aromatic silanes (4-Y-C(6)H(4)-SiH(2)X, where X = H, F, Cl, or Li). It was found that the substituent effect on the Si-H BDE of 4-Y-C(6)H(4)-SiH(3) was small, as the slope (rho(+)()) of the BDE- regression was only 0.09 kJ/mol. In comparison, the substituent effect on the Si-F BDE of 4-Y-C(6)H(4)-SiH(2)F was much stronger, whose rho(+ )()value was -2.34 kJ/mol. The substituent effect on the Si-Cl BDE of 4-Y-C(6)H(4)-SiH(2)Cl was also found to be strong with a rho(+)() value of -1.70 kJ/mol. However, the substituent effect on the Si-Li BDE of 4-Y-C(6)H(4)-SiH(2)Li was found to have a large and positive slope (+9.12 kJ/mol) against. The origin of the above remarkably different substituent effects on the Si-X BDEs was found to be associated with the ability of the substituent to stabilize or destabilize the starting material (4-Y-C(6)H(4)-SiH(2)X) as well as the product (4-Y-C(6)H(4)-SiH(2)* radical) of the homolysis. Therefore, the direction and magnitude of the effects of Y-substituents on the Z-X BDEs in compounds such as 4-YC(6)H(4)Z-X should have some important dependence on the polarity of the Z-X bond undergoing homolysis. This conclusion was in agreement with that from earlier studies (for example, J. Am. Chem. Soc. 1991, 113, 9363). However, it indicated that the proposal from a recent work (J. Am. Chem. Soc. 2001, 123, 5518) was unfortunately not justified.     

EFFECTS OF IONOPHORES AND RUTHENIUM RED ON THE PHOTOTAXIS OF STENTOR COERULEUS AS MEASURED BY SIMPLE DEVICES

Abstract— Two simple methods of phototaxis measurements have been applied to study the effects of ionophores on the negative phototactic response in Stentor coeruleus. The inhibitory effects of Ca²⁺-ionophore (A23187), Ca²⁺-blocking agent (Ruthenium Red), and K⁺ -ionophore (valinomycin) on photo-taxis have been determined. Results suggest that the influx of Ca²⁺ plays a transducing role in the phototaxis of Stentor.     

用硼酸作催化剂一锅法合成双（二氢化嘧啶酮-4-基）苯

A simple effective synthesis of bis(dihydropyrimidinone-4-yl)benzene derivatives, using boric acid as catalyst,from isophthalic aldehyde or terephthalic aldehyde, 1,3-dicarbonyl compounds and urea or thiourea in glacial acetic acid was described. As the expansion of the classical Biginelli reaction, this method has the advantage of excellent yields 83%-94% and short reaction time 0.5-1.5 h.     

Spontaneous fractal aggregation of gold nanoparticles and controlled generation of aggregate-based fractal networks at air/water interface

The spontaneous fractal aggregation of as-prepared cetytrimethylammonium bromide (CTAB)-capped gold nanoparticles was found to happen at the air/water interface after spreading their chloroform solution on water surfaces. Aided by Langmuir-Blodgett techniques, these fractal aggregates can be interconnected with each other to form aggregate-based fractal networks.     

Self-assembly of meso-tetrakis(4-N-ethylpyridiniurmyl) porphyrin and tetracarboxyl-phenyl calix[4]arene

Novel dimeric capsules are generated from the noncovalent assembly of 5, 10, 15, 20-tetrakis(4-N-ethylpyridiniurmyl)prophyrin (TEPyP) and tetracarboxyl-phenyl calix[4]arene. The self-assembly system was investigated based on UV-Vis absorption and fluorescent spectra. The factors affecting the interaction process including pH and concentration were examined in detail. The association constants between TEPyP and calix[4]arene were determined by the nonlinear least squares fit. The results showed that the basic medium is favourable to the interaction and electrostatic interaction was determinate in the processes of self-assembly process. The related mechanism was discussed.     

Synthesis and Characterization of Diphenyltin(IV) Dicarboxylates Containing Germanium

Twelve new germanium substituted diphenyltin dipropionates with the general formula (R¹GeCHR²‐CHR³COO)₂SnPh₂ where R¹ = N(CH₂CH₂O)₃, (C₆H₅)₃ and (CH₃C₆H₄)₃, R² = H, CH₃, C₆H₅, p‐CH₃C₆H₄, p‐CH₃OC₆H₄, p‐ClC₆H₄, and R³ = H, CH₃ have been synthesized by the reaction of diphenyltin oxide with a germanium substituted propionic acid. All the compounds were characterized by elemental analysis, IR, multi‐nuclear (¹H, ¹³C, ¹¹⁹Sn) NMR and Mössbauer spectroscopies as well as mass spectrometry. The in vitro antibacterial activity of selected compounds is also reported.     

Preparation of nickel-mesoporous materials and their application to the hydrodechlorination of chlorinated organic compounds

Mesoporous materials have attracted considerable attention for use as a catalyst or a catalyst support due to their remarkable textural properties such as high surface area and large pore volume with a narrow pore size distribution. Many efforts have been made to design mesoporous materials for use in heterogeneous catalyst systems. Recent progress and results regarding the preparation of nickel-mesoporous materials and their application to the hydrodechlorination of chlorinated organic compounds were discussed in this review. Mesoporous materials were used as a support for nickel catalyst or a nickel-incorporated mesoporous catalytic material in this work. Two research areas were described and discussed in this review. One is the preparation of mesoporous alumina-supported nickel catalysts and their application to the hydrodechlorination of 1,2-dichloropropane and o-dichlorobenzene. The other is the preparation of mesoporous silica-supported nickel catalysts and their application to the hydrodechlorination of 1,1,2-trichloroethane and chlorobenzene.