Risk factors and outcomes of cytomegalovirus viremia in pediatric hematopoietic stem cell transplantation patients.

BACKGROUND: Cytomegalovirus (CMV) is a major pathogen causing significant mortality and morbidity in immunocompromised hosts. It is important to find risk factors associated with CMV viremia and its outcome. METHODS: We investigated the incidence, time of onset, risk factors for CMV viremia, and characteristics of CMV diseases in 57 pediatric patients receiving hematopoietic stem cell transplantation (HSCT). Between August 2011 and March 2014, cases of pediatric HSCT patients at the National Taiwan University Children's Hospital were reviewed. Viremia was identified by plasma CMV real-time polymerase chain reaction (RT-PCR) assay. RESULTS: Eighteen (32%) of the 57 patients developed CMV viremia at a median of 23 days post-HSCT (range -3 to +721 days). Eighty-nine percent (16/18) of CMV viremia occurred within 100 days posttransplantation. Four patients finally had CMV diseases (1 with CMV colitis and 3 with CMV pneumonitis) and one patient died of CMV pneumonitis complicated with pulmonary hemorrhage and sepsis. Significant risk factors associated with CMV viremia via univariate analysis include older age (p = 0.03), leukemic patients [odds ratio (OR): 5.2, 95% confidence interval (CI): 1.52∼17.7, p = 0.008), allogeneic HSCT (OR: 14.57, 95% CI: 1.76∼120.5, p = 0.002), antithymoglobulin (ATG) use before transplantation (OR: 5.09, 95% CI: 1.52∼16.9, p = 0.007), graft-versus-host disease (GvHD) (OR: 10.1, 95% CI: 2.7∼38.7, p < 0.001), and gastrointestinal GvHD (OR: 10.9, 95% CI: 2.72∼43.9, p = 0.001). CONCLUSION: In pediatric posttransplantation patients, CMV viremia mostly occurred within 100 days after transplantation. Risk factors associated with CMV viremia include older diagnostic age, leukemic patients, unrelated donor HSCT, pretransplant ATG use, GvHD, and gastrointestinal GvHD.

Traceless labeling of glycoproteins and its application to the study of glycoprotein-protein interactions.

A new chemical method for the traceless labeling of glycoproteins with synthetic boronic acid (BA)-tosyl probes was successfully developed. The BA moiety acts as an affinity head to direct the formation of a cyclic boronate diester with the diol groups of glycans. Following this step, the electrophilic tosyl group is displaced by an SN2 reaction with a nucleophilic residue of the boronated glycoprotein, and finally, a reporter group is tagged onto the glycoprotein via an ether linkage. In the presence of polyols, a competition reaction recovers the native glycan of the tagged glycoprotein, conserving its biological significance. The BA-tosyl probes were used successfully for the specific labeling of glycosylated fetuins in a mixed protein pool and from crude Escherichia coli (E. coli) lysate. Further, a BA-tosyl-functionalized glass slide was used to fabricate glycoprotein microarrays with highly conserved glycans. By interacting with various lectins (carbohydrate-binding proteins), such as Concanavalin A (Con A) and wheat germ agglutinin (WGA), the types of carbohydrates and specific linkages of glycoproteins (α or ß) could be systematically monitored. It is believed that the newly developed method will greatly accelerate the understanding of glycoproteins.

Direct monitoring of chemical transformations by combining thin layer chromatography with nanoparticle-assisted laser desorption/ionization mass spectrometry.

A nanomaterial-assisted method that combines thin layer chromatography (TLC) with matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) was developed to directly monitor chemical transformations. A substrate-dependent extraction strategy was studied and successfully used to identify target molecules from the depths of a developed TLC plate. By using this strategy, a hydrophobic sample of interest was enriched on the surface of the TLC plate in the presence of acetonitrile, in contrast to using water and methanol to identify hydrophilic samples. The successful enrichment of samples by specific solvents provided stable desorption/ionization efficiencies of compounds of interest and led to very good sensitivity near the attomole scale. The method was then used to monitor 4-dimethylaminopyridine (DMAP)-catalyzed acylation in preparation of bifunctional sulfonamides. The labile DMAP-acyl intermediate and final sulfonamide product were clearly identified on TLC plates without external purification or sample preparation. Furthermore, in combination with collision-induced dissociation (CID) to provide structural information, the technique was successfully used in the natural product discovery of anti-inflammatory flavonoids from Helminthostachys zeylanica, a traditional Chinese herb. The newly proposed method provides a very low background from silica supports or organic matrices in the low molecular weight range (100-1000 Da). The technique may greatly accelerate studies of metabolomics, drug discovery, and organic synthesis.