Biomedical subjects
Publications and source records attributed to Xiu-Hua Xu.
Both L- and D-beta-3'-deoxy-3',3'-difluoronucleosides were synthesized starting from the key intermediate difluorohomoallyl alcohol 11. Deoxo-Fluor was accidentally found to be efficient in reversing the hydroxyl configuration of 34, and the desired product 41 was provided in good yield.
An investigation into the dependence of the framework formation of coordination architectures on ligand spacers and terminal groups was reported based on the self-assembly of AgClO4 and eight structurally related flexible dithioether ligands, RS(CH2)nSR (Lan, R = ethyl group; Lbn, R = benzyl group, n= 1-4). Eight novel metal-organic architectures, [Ag(La1)3/2ClO4]n (1a), [Ag2(La2)2(ClO4)2]2 (2a), [AgLa3ClO4]n (3a), {[Ag(La4)2]ClO4}n (4a), [AgLb1ClO4]2 (1b), [Ag(Lb2)2]ClO4 (2b), {[Ag(Lb3)3/2(ClO4)1/2](ClO4)1/2}n (3b) and [Ag(Lb4)3/2ClO4]n(4b), were synthesized and structurally characterized by X-ray crystallography. Structure diversities were observed for these complexes: 1a forms a 2-D (6,3) net, while 2a is a discrete tetranuclear complex, in which the AgI ion adopts linear and tetrahedral coordination modes, and the S donors in each ligand show monodentate terminal and mu2-S bridging coordination fashions; 3a has a chiral helical chain structure in which two homo-chiral right-handed single helical chains (Ag-La3-)n are bound together through mu2-S donors, and simultaneously gives rise to left-handed helical entity (Ag-S-)n. In 4a, left- and right-handed helical chains formed by the ligands bridging AgI centers are further linked alternately by single-bridging ligands to form a non-chiral 2-D framework. 1b has a dinuclear structure showing obvious ligand-sustained Ag-Ag interaction, while 2b is a mononuclear complex; 3b is a 3-D framework formed by ClO4- linking the 2-D (6,3) framework, which is similar to that of 1a, and 4b has a single, double-bridging chain structure in which 14-membered dinuclear ring units formed through two ligands bridging two AgI ions are further linked by single-bridging ligands. In addition, a systematic structural comparison of these complexes and other reported AgClO4 complexes of analogous dithioether ligands indicates that the ligand spacers and terminal groups take essential roles on the framework formation of the AgI complexes, and this present feasible ways for adjusting the structures of such complexes by modifying the ligand spacers and terminal groups.
OBJECTIVE: To investigate the incidence and pathogens of nosocomial bacteremia (NB) in China. METHODS: The data of incidence and pathogens of NB reported from Jun 1998 to Dec 2001 by the hospitals of the Chinese nosocomial infections surveillance system (CNISS) were collected and analyzed. RESULTS: A total of 4882364 patients were surveyed and 2 371 cases of NB were reported. The incidence rate of NB was 48.6/100000, accounting for 1.3% of nosocomial infection. The incidence of bacteremia was higher in units of hematology, infectious disease, neonatology, and burns, and among the surgical patients with contaminated wound. 1757 strains of pathogens had been isolated, among which 585 (33.3%) were gram-positive bacteria, 962 (54.8%) gram-negative bacteria, 186 (10.6%) fungi, and 24 (1.4%) other pathogens. The most common pathogens were Escherichia coli (17.2%), Coagulase negative staphylococcus (CoNS 13.4%), fungi (10.6%), Klebsiella (9.1%), Staphylococcus aureus (8.1%), Pseudomonas aeruginosa (6.8%), and Enterobactor (6.3%) spp. CONCLUSION: Patients in unit of hematology, infectious diseases, burns and neonatology and surgical patients with class III incision have higher incidence of nosocomial bacteremia. Gram-negative bacteria were the prominent pathogens, the most common pathogens were E. coli, CoNS, fungi, Klebsiella, S. aureus, P. aeruginosa, and Enterobactor spp.