Synthesis of Chiral Diarylmethylamides via Catalytic Asymmetric Aza-Michael Addition of Amides to ortho-Quinomethanes.

Chiral diarylmethylamides are a privileged skeleton in many bioactive molecules. However, the enantioselective synthesis of such molecules remains a long-standing challenge in organic synthesis. Herein, we report a chiral bifunctional squaramide catalyzed asymmetric aza-Michael addition of amides to in situ generated ortho-quinomethanes, affording enantioenriched diarylmethylamides in good yields with excellent enantioselectivities. This work not only provides a new strategy for the construction of the diarylmethylamides but also represents the practicability of amides as nitrogen-nucleophiles in asymmetric organocatalysis.

Diastereo- and Enantioselective Synthesis of Eight-Membered N-Heterocycles from Benzofuran-Derived Azadienes and Ynones.

Enantioselective synthesis of eight-membered N-heterocycles represents a long-standing challenge in organic synthesis. Here, by combining the squaramide and DBU catalysis, a sequential asymmetric conjugate addition/cyclization reaction between benzofuran-derived azadienes and ynones has been well-developed, providing straightforward access to chiral eight-membered N-heterocycles in high yields with stereoselectivities. This protocol features the use of a bifunctional squaramide catalyst for controlling the enantioselectivity of products, while the DBU is utilized to achieve intramolecular cyclization and improve the diastereoselectivity of products.

Metal-free and enantioselective synthesis of 1,4-benzoxazepines from para-quinone methide derivatives and α-bromohydroxamates.

A sequential asymmetric conjugate addition/cyclisation of α-bromohydroxamates with para-quinone methide derivatives has been developed, which provides enantioenriched 1,4-benzoxazepines in generally high yields (up to 95%) and good enantioselectivities (up to 97 : 3 er). This protocol not only offers a novel and straightforward strategy for constructing chiral 1,4-benzoxazepines, but also demonstrates the potential of α-bromohydroxamates as three-atom synthons in asymmetric cyclisation reactions.

Copper-catalyzed asymmetric 1,6-conjugate addition of in situ generated para-quinone methides with ß-ketoesters.

A Cu-catalyzed asymmetric 1,6-conjugate addition of in situ generated para-quinone methides (p-QMs) with ß-ketoester has been developed to construct a ketoester skeleton bearing an adjacent tertiary-quaternary carbon stereocenter in good yields and high enantioselectivities. This is the first example of metal-catalyzed asymmetric transformations of the in situ generated p-QMs, avoiding using pre-synthesized p-QMs requiring bulky 2,6-substitutions and highlighting a new dual catalytic activation with the chiral bis(oxazoline)-metal complex acting as a normal Lewis acid to activate the ß-ketoesters and a source of Brønsted acid responsible for generating the p-QMs in situ.

[Cultivation, screening, identification and transplantation of Muse cell from human umbilical cord-derived for spinal cord injury in rats].

OBJECTIVE: To investigate multilineage-differentiating stress-enduring (Muse) by immunomagnetic bead screening from Wharton's jelly mesenchymal stromal cells(WJ-MSCs), and explore transplantation of Muse cell for safety and effectivensess of sub acute cord injury in rats. METHODS: Donated Wharton's Jelly-mesenchymal stromal cells (WJ-MSCs) were successfully derived from a human umbilical cord by a series of procedures namely physical isolation of Wharton's Jelly from cord membrane, collagenase and trypsin treatment and density gradient centrifugation. Magnetic activated cell sorting was performed to specifically select SSEA3+ Muse cells, and flow cytometry and immunocytochemistry were used to identify further. In vivo, spinal cord contusion injury model in rats was induced by NYU-III impactor, and were randomly divided and equally into four groups, namely group A (sham), group B (control), group C (Non-Muse cells transplantation) and group D (Muse cells transplantation). Laminectomy was conducted in group A but no spinal cord contusion injury. Laminectomy and cord injury were performed in group B, C and D, 10 g trip rod was freely falling down from 12.5 mm. Two weeks later, group B, C and D were received PBS injection, Non-Muse cells transplantation and Muse cells transplantation respectively, four-point injection were performed in each cord with totally 4×105 cells. BBB scores were evaluated on 1 day, 1, 2, 3, 4, 5 and 6 week after injury. Four weeks after cell transplantation, the rats were sacrificed, and immunohistochemistry were carried out to observe survival, migration and differentiation of the injected cells. RESULTS: The expression of CD105, CD90 and CD73 were over 99.5% in the derived WJ-MSCs population, but CD45 and CD14 were lower than 0.5%, positive rate of SSEA3+ was 1.46% under flow cytometer, However, after MACS sorting, the percentage of 92.0% Muse cells expressed SSEA3 and CD105, and immunohistochemistry results of SSEA3 showed typically membrane morphology with special processes. In vivo, BBB scores was 21 in group A at different time points. One-way ANOVA and LSD analysis showed that BBB scores in group C and D were significantly higher than that in group B (P=0.004, 0.002), but there was no significantly difference between group C and D. Further intra-group paired t test showed that BBB score was significantly higher at 4 weeks than that 3 weeks in group C (P=0.005). However, in group D, BBB scores were significantly higher at 4 and 6 week than those at 3 and 5 weeks, P values were 0.005 and 0.016 respectively. Immunohistochemistry results showed that both Muse cells and Non-Muse cells could survive for 4 weeks in rats and they migrated from the four-point injection to injury site. But there showed more Muse cells survival than Non-Muse cells in the cord. CONCLUSIONS: Immunomagnetic bead screening is efficient to select large number of purified SSEA3+ Muse cells. Muse cells could survive and target-migrate in injured cord to improve BBB scores continuously. Muse cells are a novel kind of seed cells in the spinal cord injury treatment.

Isolation of antimicrobial resistant bacteria in upper respiratory tract infections of patients.

Haemophilus influenzae, Streptococcus pyogenes, Moraxella catarrhalis, Staphylococcus aureus, and Streptococcus pneumoniae are usual cause of upper respiratory tract infection cases. The present study aims the isolation of bacterial strains which are resistant to the commonly prescribed antibiotics. In total, 900 throat swabs were obtained from the patients suffering from upper respiratory tract infections residing in three different localities. The maximum number of isolates (64 %) were obtained from locality-1 (L-1), whereas lowest isolates were found in second locality (L-2). H. influenzae was found to be the most dominant bacterial pathogen in upper respiratory tract infections in patients with 42 % of the total isolates. H. influenzae and Chlamydia pneumoniae were resistant to ß-lactam antibiotics but susceptible to fluroquinolones and aminoglycosides, whereas S. aureus and S. pneumoniae were found to be highly resistant to ß-lactam, aminoglycosides and fluroquinolones. S. aureus was also moderately resistant to fluroquinolones and aminoglycosides with percent resistance of 26, 33 and 18 %, respectively. 56 % S. pneumoniae isolates were resistant against erythromycin, 27 % against chloramphenicol and 23 % against cefuroxime. The studies revealed that S. aureus and S. pneumoniae strains were high producer of biofilms which could be one of the reasons for their high pathogenicity.

[Mannan-Binding Lectin Inhibits Candida Albicans-Induced DC Maturation and Cytokine Secretion].

OBJECTIVE: To investigate the effects of mannan-binding lectin (MBL) on the maturation and cytokine secretion of human dendritic cells (DC) induced by Candida albicans (C. albicans). METHODS: The plastic-adherent mononuclear cells were prepared from the blood of healthy adult volunteers. The human peripheral blood mononuclear cells-derived dendritic cells (MNC-DC) were induced by 5-day-culture in medium supplemented with rhGM-CSF and rhIL-4, and then cultured for 2 days in presence or absence of C. albicans at varying concentration of human MBL ranging from 1 to 20 mg/L. DC's shape and characters were observed under inverted microscopy, the expression of CD83 and CD86 on DC was analyzed by FACS. The levels of TNF-α and IL-6 were detected by ELISA. FACS also was used to investigate the interaction of MBL with immature DC(imDC) and C. albicans. Western blot was used to detect C. albicans-induced IκBα phosphorylation and p65/NF-κB translocation in DC. RESULTS: MBL at higher concentrations (10-20 mg/L) down-regulated the expression of CD83 and CD86 on the monocyte-derived dentritic cells(MoDC) induced by C. albicans, and inhibited the production of TNF-α and IL-6 induced by C. albicans. FACS showed that MBL could not only bind to C. albicans but also bind to imDCs in a Ca2+-dependent manner. Western blot showed that MBL could decrease the phosphorylation of IκBα and the nuclear translocation of p65/ NF-κB. CONCLUSION: MBL may inhibit TNF-α and IL-6 production induced by C. albicans in DC through NF-κB signaling pathways, suggesting that MBL can play some roles in the regulation of C. albicans-induced immune response.

[Distribution of Bifidobacterium in oral cavities of children and the relations with caries].

OBJECTIVE: To explore a selected-media of Bifidobacterium from oral cavity, to detect the distribution of Bifidobacterium in different sites of children and primarily investigate the relationship between oral Bifidobacterium and early childhood caries. METHODS: 70 children aged from 3 to 5-year-old were selected, 30 children were caries-free and 40 were severe early childhood caries (S-ECC). Saliva was collected and plaque samples from the 30 healthy subjects were pooled. For S-ECC group, plaques were collected separately from four different sites as follows: Saliva, surfaces of intact enamel, surfaces of white spot-lesions, and deep dentin-lesions. Samples would be grown in the selected-media, and the whole DNA of bacteria was extracted. Polymerase chain reaction was performed with specific primers and the results were analyzed by the electrophoresis. RESULTS: Bifidobacterium were detected 0 in the caries-free children, while 47.5% in the S-ECC group. There was significant difference between two groups (P < 0.05) and there was no difference between different sites of teeth in S-ECC group (P > 0.05). 27.5% Bifidobacterium were detected in saliva, 27.5% on surfaces of intact enamel, 20.0% on surfaces of white spot-lesions and 22.5% in deep dentin-lesions. 10% Bifidobacterium dentium were detected in saliva, 7.5% on surfaces of intact enamel, 7.5% on surfaces of white spot-lesions and 10.0% in deep dentin-lesions. CONCLUSION: One type of modified selected media of Bifidobacterium in oral cavity was explored. Bifidobacterium may be related to the occurrence of the S-ECC and has nothing to do with different sites of teeth in children.