Neutral polysaccharide from Panax notoginseng enhanced cyclophosphamide antitumor efficacy in hepatoma H22-bearing mice.

BACKGROUND: Our previous studies demonstrated that the administration of crude Polysaccharide from Panax notoginseng (CPPN) can effectively prolong the lifespan of tumor-bearing mice via boosting the host immune system as well as weak cytotoxicity against hepatocellular carcinoma (HCC). In the present study, Neutral Polysaccharide (NPPN) were further purified from crude polysaccharide isolated from panax notoginseng. The effects of NPPN on the immune function and hematopoietic function of mice with low immunity and myelosuppression induced by cyclophosphamide (CTX) were investigated. The effect of NPPN combined with CTX on the tumor inhibition rate of the H22 tumor-bearing mice and the impact of NPPN on the proliferation of H22 liver cancer cells in vitro were investigated. METHODS: CPPN was obtained by water extraction and alcohol precipitation method, and further purified by DEAE Sepharose Fast Flow ion exchange resin column. NPPN was added to the immunosuppressed with myelosuppression mice induced by CTX. Thymus index, spleen index, lymphocyte proliferation stimulation index by adding of concanavalin A, determination of serum hemolysin, NK cell activity assay, mice carbon clearance experiment, blood count tests were detected. The tumor inhibition rate of the H22 tumor-bearing mice treated with NPPN combined with CTX was recorded. RESULTS: NPPN and 4 kinds of acid polysaccharide from Panax notoginseng (APPN) were successfully isolated from the CPPN by DEAE Sepharose Fast Flow ion exchange resin column. NPPN inhibited the growth of H22 cells and significantly increase the tumor inhibition rate of the H22 tumor-bearing mice combined with CTX. The elevation of the cellular and humoral immunity levels as well as a variety of blood count tests indicators of immunosuppressive with myelosuppression mice may contribute to the antitumor activity of NPPN. CONCLUSION: NPPN has a potential antitumor activity for the treatment of liver cancer combined with cyclophosphamide.

Highly active bidentate N-heterocyclic carbene/ruthenium complexes performing dehydrogenative coupling of alcohols and hydroxides in open air.

Eight bidentate NHC/Ru complexes, namely [Ru]-1-[Ru]-8, were designed and prepared. In particular, [Ru]-2 displayed extraordinary performance even in open air for the dehydrogenative coupling of alcohols and hydroxides. Notably, an unprecedentedly low catalyst loading of 250 ppm and the highest TON of 32 800 and TOF of 3200 until now were obtained.

Ruthenium-Based Catalytic Systems Incorporating a Labile Cyclooctadiene Ligand with N-Heterocyclic Carbene Precursors for the Atom-Economic Alcohol Amidation Using Amines.

Transition-metal-catalyzed amide-bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol.%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further high-resolution mass spectrometry (HRMS) analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.

In†situ Generated Ruthenium Catalyst Systems Bearing Diverse N-Heterocyclic Carbene Precursors for Atom-Economic Amide Synthesis from Alcohols and Amines.

The transition-metal-catalyzed direct synthesis of amides from alcohols and amines is herein demonstrated as a highly environmentally benign and atom-economic process. Among various catalyst systems, in situ generated N-heterocyclic carbene (NHC)-based ruthenium (Ru) halide catalyst systems have been proven to be active for this transformation. However, these existing catalyst systems usually require an additional ligand to achieve satisfactory results. In this work, through extensive screening of a diverse variety of NHC precursors, we discovered an active in situ catalyst system for efficient amide synthesis without any additional ligand. Notably, this catalyst system was found to be insensitive to the electronic effects of the substrates, and various electron-deficient substrates, which were not highly reactive with our previous catalyst systems, could be employed to afford the corresponding amides efficiently. Furthermore, mechanistic investigations were performed to provide a rationale for the high activity of the optimized catalyst system. NMR-scale reactions indicated that the rapid formation of a Ru hydride intermediate (signal at δ=-7.8 ppm in the 1 H NMR spectrum) after the addition of the alcohol substrate should be pivotal in establishing the high catalyst activity. Besides, HRMS analysis provided possible structures of the in situ generated catalyst system.

[Expression of B7 Family Co-inhibitory Molecules in the Establishment of Pulmonary Regional Immunity].

OBJECTIVE: To identify the temporal-spatial expression of B7 family co-inhibitory molecules during lung development, and to explore the roles of B7 family co-inhibitory molecules in the developmental process of pulmonary regional immunity. METHODS: The expression of B7 family co-inhibitory molecules (B7-1, B7-2, B7-H1, B7-DC) in different developmental stages of Rhesus monkey lungs were normalized and calculated by the reads per kilo-base of transcript per million mapped reads (RPKM) method. Immunohistochemical staining was performed to identify the localization and the protein of B7 family co-inhibitory molecules in different developmental phase (canalicular stage, cystic stage, alveolar stage) in mouse. RESULTS: The expression of B7 family co-inhibitory molecules in rhesus monkey were increased during the prenatal period (cystic stage, alveolar stage), the expressions of B7-2 and B7-H1 mRNA were significantly increased in alveolar stage (P<0.05). The results of immuno-histochemistry indicated that B7 family co-inhibitory molecules were mainly expressed in airway epithelial cells, and their protein levels were increased during the prenatal period. The expressions of B7-2, B7-H1 and B7-DC were significantly increased from canalicular stage (P<0.05). The protein of B7-2 was higher in airway than that in bronchus (P<0.05). CONCLUSIONS: B7 family co-inhibitory molecules are mainly expressed in airway epithelial cells, and the expressions are increased during the prenatal period, which suggests that B7 family co-inhibitory molecules are involved possibly in the development of pulmonary regional immunity.

Characterization of a Novel Dengue Serotype 4 Virus-Specific Neutralizing Epitope on the Envelope Protein Domain III.

The dengue virus (DENV) envelope protein domain III (ED3) has been suggested to contain receptor recognition sites and the critical neutralizing epitopes. Up to date, relatively little work has been done on fine mapping of neutralizing epitopes on ED3 for DENV4. In this study, a novel mouse type-specific neutralizing antibody 1G6 against DENV4 was obtained with both prophylactic and therapeutic effects. The epitope was mapped to residues 387-390 of DENV4 envelope protein. Furthermore, site-directed mutagenesis assay identified two critical residues (T388 and H390). The epitope is variable among different DENV serotypes but is highly conserved among four DENV4 genotypes. Affinity measurement showed that naturally occurring variations in ED3 outside the epitope region did not alter the binding of mAb 1G6. These findings expand our understanding of the interactions between neutralizing antibodies and the DENV4 and may be valuable for rational design of DENV vaccines and antiviral drugs.

Enlarge the training set based on inter-class relationship for face recognition from one image per person.

In some large-scale face recognition task, such as driver license identification and law enforcement, the training set only contains one image per person. This situation is referred to as one sample problem. Because many face recognition techniques implicitly assume that several (at least two) images per person are available for training, they cannot deal with the one sample problem. This paper investigates principal component analysis (PCA), Fisher linear discriminant analysis (LDA), and locality preserving projections (LPP) and shows why they cannot perform well in one sample problem. After that, this paper presents four reasons that make one sample problem itself difficult: the small sample size problem; the lack of representative samples; the underestimated intra-class variation; and the overestimated inter-class variation. Based on the analysis, this paper proposes to enlarge the training set based on the inter-class relationship. This paper also extends LDA and LPP to extract features from the enlarged training set. The experimental results show the effectiveness of the proposed method.

Immunization with HBsAg-Fc fusion protein induces a predominant production of Th1 cytokines and reduces HBsAg level in transgenic mice.

BACKGROUND: The Fc receptor associated pathway might improve the immune responses against hepatitis B virus (HBV) as previously described by us. In addition, the Flt3 ligand (FL) has been reported to potentiate antigen presenting cells in vivo and may act as a potential adjuvant to boost antigen-specific immune responses. In this study, the immune efficacies of a set of fusion proteins of HBsAg and Fc and/or FL were evaluated in HBsAg transgenic mice. METHODS: The fusion proteins composed of HBsAg and the Fc domain of murine IgG1 (HBsAg-Fc) and/or the Flt3 ligand, and yeast-derived recombinant HBsAg were used as immunogen to immunize HBsAg transgenic mice, respectively. Serum and liver HBsAg levels, serum anti-HBsAg and cytokine profile, and the activities of alanine aminotransferase (ALT)/AST were investigated after immunization. RESULTS: After six injections, the most pronounced decrease in serum and liver HBsAg levels was observed in the HBsAg-Fc immunized group. In addition, serum Th1 cytokines and ALT/AST activities were highest in this group, indicating an effective induction of a favorable cellular immune response. Interestingly, the fusion protein containing HBsAg-Fc and the Flt3 ligand stimulated an alternative Th1-type immune response featured with high level productions of tumor necrosis factor α (TNF-α) and monocyte chemoabstractant protein 1 (MCP-1), causing a more severe cytotoxicity in hepatocytes while showed less effective in reducing serum HBsAg level. CONCLUSION: HBsAg-Fc is effective in eliciting both the humoral and cellular immune responses against HBsAg in HBsAg transgenic mice, which makes it a potential immunogen for the immunotherapy of chronic hepatitis B.

Hydride dissociation energies of six-membered heterocyclic organic hydrides predicted by ONIOM-G4Method.

Hydride dissociation energy is of great importance in understanding the hydride-donating abilities of organic hydrides. Although the hydride dissociation energies of some organic hydrides have been experimentally measured, much less attention has been focused on the investigation of these quantities from the first principles of physics. Herein, we developed an ONIOM-G4 method and carefully benchmarked this new method against 48 experimental hydride dissociation energies of diverse bulky molecules. It was found that with the combined methods of the HF/6-31+G(d,p)//IEFPCM/Bondi1.15 solvation model, the ONIOM-G4 method can predict the hydride dissociation energies with an error bar of only 1.7 kcal/mol. With the newly developed ONIOM-G4 method, we then systematically studied the hydride dissociation energies of six categories of biologically and pharmaceutically important six-membered heterocyclic organic hydrides, namely, the organic hydrides containing 1,4-dihydropyridine, 1,4-dihydropyrazine, 1,4-oxazine, 1,4-thiazine, 4H-pyran, and 4H-thiopyran ring structures. An extensive hydride dissociation energy scale containing over 100 six-memebered heterocyclic organic hydrides has been established, which may find applications in both synthetic organic chemistry and mechanistic studies of various chemical or biological processes involving transferring of the hydride anion.

A broadly flavivirus cross-neutralizing monoclonal antibody that recognizes a novel epitope within the fusion loop of E protein.

Flaviviruses are a group of human pathogenic, enveloped RNA viruses that includes dengue (DENV), yellow fever (YFV), West Nile (WNV), and Japanese encephalitis (JEV) viruses. Cross-reactive antibodies against Flavivirus have been described, but most of them are generally weakly neutralizing. In this study, a novel monoclonal antibody, designated mAb 2A10G6, was determined to have broad cross-reactivity with DENV 1-4, YFV, WNV, JEV, and TBEV. Phage-display biopanning and structure modeling mapped 2A10G6 to a new epitope within the highly conserved flavivirus fusion loop peptide, the (98)DRXW(101) motif. Moreover, in vitro and in vivo experiments demonstrated that 2A10G6 potently neutralizes DENV 1-4, YFV, and WNV and confers protection from lethal challenge with DENV 1-4 and WNV in murine model. Furthermore, functional studies revealed that 2A10G6 blocks infection at a step after viral attachment. These results define a novel broadly flavivirus cross-reactive mAb with highly neutralizing activity that can be further developed as a therapeutic agent against severe flavivirus infections in humans.

[Correlation analysis of collateral circulation and clinical locations in patients with ischemic stroke].

OBJECTIVE: To study the correlation of compensation by collateral circulation and clinical locations in ischemic stroke cases. METHODS: A total of 25 ischemic stroke cases were retrospectively analyzed. MRI (magnetic resonance imaging) and DSA (digital subtraction angiography) were performed in all cases. Each patient was found to have at least one cerebral artery occlusion by DSA. The quantity relationship between collateral circulation and ischemic stroke location was analyzed by SPSS 11.5 statistics software. RESULTS: Among all cases, 46 arterial occlusions were found by chance. DSA demonstrated internal carotid artery occlusion (n = 24) and vertebral & basilar artery occlusion (n = 22). And all cases had at least one collateral circulation. Among 23 cases of single collateral circulation, there were 8 cases of single ischemic stroke locations and 15 cases of multiple ischemic stroke locations; among 23 cases of multiple collateral circulations, there were 18 cases of single ischemic stroke locations and 5 cases of multiple ischemic stroke locations. CONCLUSION: Effective collateral circulation can be established spontaneously through multiple ways when cerebral artery occlusion takes place if an intact Wills circle is present. Multiple collateral circulations may significantly decrease the quantity of ischemic stroke locations.

Theoretical study on acidities of (S)-proline amide derivatives in DMSO and its implications for organocatalysis.

The acidities (pK(a) values) of proline amide derivatives are of great importance for understanding the catalytic activity of proline-based organocatalysts. The development of new catalysts could also benefit from the systematic study of the pK(a) values of these compounds. However, only a few pK(a) values of the proline-based organocatalysts are currently available due to the difficulty in experimentally measurements. In this work, we set out to study the pK(a) values of various proline amide derivatives with theoretical calculations. Different theoretical methods were evaluated and the combined method, B3PW91/6-311++G(3df,2p)//B3LYP/6-31+G(d)//HF//CPCM/UA0, was found to be the best one in reproducing the pK(a) values of structurally unrelated amides and amide derivatives in DMSO. The MAD and RMSE of the newly developed theoretical model equal to 0.98 and 1.3 pK units, respectively. The method also enabled the systematically study on various structural effects on pK(a) values of proline amide derivatives, such as the ZE-isomerization, remote substitution, and alpha-substitution effects, for the first time. The pK(a) values of a series of chiral amides were also studied in this work. Finally, we applied the theoretical method to predict a large number of proline-based organocatalysts and established an extensive acidity scale of the compounds.

An extensive ylide thermodynamic stability scale predicted by first-principle calculations.

Thermodynamic stabilities of ylides are measured by the ease of the carbanion formation through the removal of a proton from their precursors. A full-spectrum scale of ylide thermodynamic stability is important to understand the reactivities and selectivities in ylide chemistry. In the present study is reported the first theoretical protocol for predicting the acidities of structurally unrelated ylide precursors in DMSO whose reliability has been tested against almost all the available experimental data. The ONIOM/G3B3//HF//CPCM/Bondi method is found to be the optimal protocol to handle the N-, P-, and S-containing ylides, whereas the B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d)//HF//CPCM/Bondi method can be used to deal with those systems for which the ONIOM/G3B3 method is not feasible. Extensive calculations on about 80 experimentally characterized ylide precursors show that this theoretical protocol can reliably predict the pK(a) values of diverse structurally unrelated ylide precursors in DMSO with an error bar of ca. 1.6-1.9 pK(a) units. With the authorized theoretical protocol in hand, we have developed an extensive scale of ylide thermodynamic stability that may find applications in synthetic organic chemistry.