Cationic Alternating Polypeptide Fixed on Polyurethane at Multiple Sites for Excellent Antibacterial and Antifouling Properties.

Bacterial infection and blockage are severe problems for polyurethane (PU) catheters and there is an urgent demand for surface-functionalized polyurethane. Herein, a cationic alternating copolymer comprising allyl-substituted ornithine and glycine (allyl-substituted poly(Orn-alter-Gly)) with abundant carbon-carbon double bond functional groups (C═C) is designed. Polyurethane is prepared with a large quantity of C═C groups (PU-D), and different amounts of allyl-substituted poly(Orn-alter-Gly) are grafted onto the PU-D surface (PU-D-2%AMPs and PU-D-20%AMPs) via the C═C functional groups. The chemical structures of the allyl-substituted poly(Orn-alter-Gly) and polyurethane samples (PU, PU-D, PU-D-2%AMPs, and PU-D-20%AMPs) are characterized and the results reveal that allyl-substituted poly(Orn-alter-Gly) is decorated on the polyurethane. PU-D-20%AMPs shows excellent antibacterial activity against Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus because of the high surface potential caused by cationic allyl-substituted poly(Orn-alter-Gly), and it also exhibits excellent long-term antibacterial activity and antibiofilm properties. PU-D-20%AMPs also has excellent antifouling properties because the cationic copolymer is fixed at multiple reactive sites, thus avoiding the formation of movable long chain brush. A strong surface hydration barrier is also formed to prevent adsorption of proteins and ions, and in vivo experiments reveal excellent biocompatibility. This flexible strategy to prepare dual-functional polyurethane surfaces with antibacterial and antifouling properties has large potential in biomedical implants.

Direct Asymmetric Vinylogous Mannich Addition of 3,5-Disubstituted-4-nitroisoxazoles to Isatin-Derived Imines Catalyzed by a Bifunctional Phase-Transfer-Catalyst.

Asymmetric Mannich-type addition of 3,5-disubstituted-4-nitroisoxazoles to isatin-derived Boc-protected imines has been realized by using 0.01 equiv of amide phosphonium salt as a phase transfer catalyst. Our current methodology allows for the formation of 3-isoxazolylmethyl-substituted 3-aminooxindoles in excellent yields with good to excellent enantioselectivities. The practical value of this methodology was exemplified by a gram-scale synthesis of 5an, a key intermediate for the formal synthesis (+)-AG-041R.

Immobilization of poly-L-lysine brush via surface initiated polymerization for the development of long-term antibacterial coating for silicone catheter.

Bacterial colonization of indwelling catheter remains a major threat in healthcare units worldwide. Developing approaches to prevent catheter-associated infections (CAIs) is, therefore, in great demand. Herein, to endow silicone catheter with long-term antibacterial properties, antimicrobial poly-L-lysine (PLL) brush was developed on the surface of catheter via surface initiated ring open polymerization. Surface characterizations confirmed the successful immobilization of PLL. The PLL-tethered catheter showed potent antibacterial activities against catheter-associated urinary tract infections (CAUTIs) related pathogens. Moreover, after immersing in simulated body fluid for 28 days or incubating at 60 °C for 65 days, the bactericidal properties of PLL-tethered catheter were still retained. Furthermore, the PLL-tethered catheter exhibited good anti-infection activity and biocompatibility in vivo. The PLL-tethered surfaces hold great potential in the development of antibacterial silicone catheter to combat CAIs in clinical applications.

Isolation and characterization of microsatellite DNA markers for the Oriental White stork, Ciconia boyciana.

Following FIASCO protocol and across-amplification approach, we present eleven microsatellite primers of the Oriental White stork, Ciconia boyciana in this article. All loci were polymorphic, except for locus Cbo235, which possessed two alleles but was homozygous in all 23 individuals of C. boyciana used in this study. The number of the alleles per locus ranged from two to eight, and the observed heterozygosity (H(o)) and expected heterozygosity (H(E)) ranged from 0 to 0.857 and 0.222 to 0.851, respectively. These markers are proved useful in genetic study of C. boyciana.

[Human stool vimentin, oncostatin M receptor and tissue factor pathway inhibitor 2 gene methylation analysis for the detection of colorectal neoplasms].

OBJECTIVE: To explore the feasibility of detecting vimentin, oncostatin M receptor (OMSR) and tissue factor pathway inhibitor 2 (TFPI2) gene methylation status in stool samples as a noninvasive screening tool for colorectal cancer and precancerous lesions. METHODS: Stool samples were collected from 60 patients with colorectal cancer, 17 patients with adenoma and 30 normal volunteers. And fecal DNA was extracted and vimentin, OMSR and TFPI2 gene methylation status was analyzed by methylation-specific polymerase chain reaction (MSP). RESULTS: The methylated vimentin, OMSR and TFPI2 was detected in 53.3% (32/60), 68.3% (41/60) and 75.0% (45/60) of colorectal cancer, and 5, 7 and 11 cases of colorectal adenoma respectively. The sensitivities of combined study, using three markers for the detection of colorectal cancer and colorectal adenomas, were 86.7% (26/30) and 76.5% (13/17) respectively. And the specificity was 86.7% (52/60). CONCLUSION: As a feasible epigenetic marker, promoter hypermethylation for vimentin, OMSR and TFPI2 in stool samples is a sensitive, specific and noninvasive alternative for colorectal cancer screening.

Intermolecular C-H silylation through cascade carbopalladation and vinylic to aryl 1,4-palladium migration.

A palladium-catalyzed remote C-H silylation reaction has been developed through vinylic to aryl 1,4-palladium migration. By using alkyne-tethered aryl iodides as the starting materials and hexamethyldisilane as the silylating reagent, the reaction involves cascade intramolecular carbopalladation, 1,4-palladium migration, and silylation with hexamethyldisilane, and leads to the formation of exocyclic alkene-containing 5-silylisoquinolines as the final products.

Diastereo- and Enantioselective Synthesis of Quaternary α-Amino Acid Precursors by Copper-Catalyzed Propargylation.

A diastereo- and enantioselective propargylic substitution reaction between propargylic carbonates and α-substituted nitroacetates catalyzed by a Cu-pybox complex is described. This method allows the preparation of a series of non-proteinogenic quaternary α-amino acid precursors featuring two contiguous stereogenic centers and a terminal alkyne moiety in high yields with good to excellent diastereo- and enantioselectivities in most cases. The propargylated adducts were elaborated into a diverse set of quaternary α-amino acid derivatives.

Asymmetric Catalytic [4 + 2] Cycloaddition via Cu-Allenylidene Intermediate: Stereoselective Synthesis of Tetrahydroquinolines Fused with a γ-Lactone Moiety.

A decarboxylative formal [4 + 2] cycloaddition reaction between ethynyl benzoxazinanones and 5-substituted 2-silyloxyfurans catalyzed by chiral Cu-Pybox complex is described. This method allows the formation of intriguing tetrahydroquinolines fused with a butyrolactone moiety featuring three contiguous chiral centers in high yields with excellent diastereo- and enantioselectivities in most cases. The utility of this method was exemplified by the removal of the N-protecting groups and derivatization on the terminal alkyne functionality of the cyclization products.

Effect of frugivorous birds on the establishment of a naturally regenerating population of Chinese yew in ex situ conservation.

The Chinese yew (Taxus chinensis) is catalogued as an endangered species in China because of the small size and senescent status of most populations. Its lack of natural regeneration is the most important reason for its endangered status. We investigated the regeneration of an ex-situ conservation population, which was introduced into the Nanjing Botanical Garden Memorial Sun Yat-Sen in the 1950s, and evaluated the role of frugivorous birds on the establishment of this regenerating population. Two hundred and thirteen individual yew seedlings and saplings were found on the hillside in 2006, and the nearest seedling was found more than 10 m away from mother trees. The spatial pattern of all seedlings and saplings occurred as a clumped distribution, which is typical for vertebrate-dispersed plants. Six bird species were seen ingesting whole "fruits" at yew trees in the present study and 745 visits by avian frugivores were recorded. Red-billed blue magpie (Urocissa erythrorhyncha), Chinese bulbul (Pycnonotus sinensis) and azure-winged magpie (Cyanopica cyana) were the most frequent visitors over the two years of the study. Comparing the flights of departure and perching habitats of the three main bird species, we inferred that U. erythrorhyncha would be the most important disperser. This regeneration population has had good development over the past 20 or more years; frugivorous birds have removed seeds to the hillside every year until now, and seed germination and seedling growth continue to develop well under natural conditions. We suggest that the conservation system of the Chinese yew should be composed of yews, avian dispersers and habitats for seed germination and seedling growth.