Two Beta-Phosphorylamide Compounds as Ligands for Sm3+, Eu3+, and Tb3+: X-ray Crystallography and Luminescence Properties.

This paper describes the synthesis of two beta-phosphorylamide ligands and their coordination chemistry with the Ln ions Tb3+, Eu3+, and Sm3+. Both the ligands and Ln complexes were characterized by IR, NMR, MS, and X-ray crystallography. The luminescence properties of the Tb3+ and Eu3+ complexes were also characterized, including the acquisition of lifetime decay curves. In the solid state, the Tb3+ and Sm3+ ligand complexes were found to have a 2:2 stoichiometry when analyzed by X-ray diffraction. In these structures, the Ln ion was bound by both oxygen atoms of each beta-phosphorylamide moiety of the ligands. The Tb3+ and Eu3+ complexes were modestly emissive as solutions in acetonitrile, with lifetime values that fell within typical ranges.

Mucosal barrier injury-associated bloodstream infections in pediatric oncology patients.

BACKGROUND: Single-center reports of central line-associated bloodstream infection (CLABSI) and the subcategory of mucosal barrier injury laboratory-confirmed bloodstream infection (MBI-LCBI) in pediatric hematology oncology transplant (PHO) patients have focused on the inpatient setting. Characterization of MBI-LCBI across PHO centers and management settings (inpatient and ambulatory) is urgently needed to inform surveillance and prevention strategies. METHODS: Prospectively collected data from August 1, 2013, to December 31, 2015, on CLABSI (including MBI-LCBI) from a US PHO multicenter quality improvement network database was analyzed. CDC National Healthcare Safety Network definitions were applied for inpatient events and adapted for ambulatory events. RESULTS: Thirty-five PHO centers reported 401 ambulatory and 416 inpatient MBI-LCBI events. Ambulatory and inpatient MBI-LCBI rates were 0.085 and 1.01 per 1000 line days, respectively. Fifty-three percent of inpatient CLABSIs were MBI-LCBIs versus 32% in the ambulatory setting (P  <  0.01). Neutropenia was the most common criterion defining MBI-LCBI in both settings, being present in ≥90% of events. The most common organisms isolated in MBI-LCBI events were Escherichia coli (in 28% of events), Klebsiella spp. (23%), and viridans streptococci (12%) in the ambulatory setting and viridans streptococci (in 29% of events), E. coli (14%), and Klebsiella spp. (14%) in the inpatient setting. CONCLUSION: In this largest study of PHO MBI-LCBI inpatient events and the first such study in the ambulatory setting, the burden of MBI-LCBI across the continuum of care of PHO patients was substantial. These data should raise awareness of MBI-LCBI among healthcare providers for PHO patients, help benchmarking across centers, and help inform prevention and treatment strategies.

Lanthanide extraction selectivity of a tripodal carbamoylmethylphosphine oxide ligand system.

Four tripodal carbamoylmethylphosphine oxide (CMPO)-based ligands are reported here and assessed with regard to lanthanide (Ln) coordination chemistry and selective extraction of lanthanide ions from aqueous solution. Inspired by previous liquid-liquid extraction studies that suggested a preference for terbium(iii), the current work further probes the extraction behavior of a tris-(2-aminoethyl)amine (TREN) capped, ethoxy substituted CMPO ligand with respect to the entire series of lanthanides. Upon confirmation of Tb3+ extraction selectivity versus the whole series, experiments were conducted to assess the effect of increasing the alkyl chain length within the ligand TREN cap, as well as changing the CMPO substituents by replacing the ethoxy groups with more hydrophobic phenyl groups to promote solubility in the organic extraction solvent. Extraction efficiencies remained low for most lanthanides upon increasing the cap size, with %E values consistently around 5%, and a complete loss of Tb3+ preference was noted with a decrease in %E from 18% to 3.5%. For the agent employing the original, smaller TREN cap but with phenyl substituents on the CMPO units, an increase in extraction toward the middle of the row was again observed, albeit modest, with relatively high %E values for both Gd3+ and Tb3+versus the other lanthanides (13 and 11%, respectively). A more dramatic extraction selectivity for the phenyl substituted ligand was achieved upon modification of the ligand to metal ratio, with a 100 : 1 ratio resulting in a near linear decrease in %E from 41% for La3+ to 3.7% for Lu3+. Finally, modification of the TREN capping scaffold by adding an oxygen atom to the central nitrogen led to consistently low %E values, revealing the effect of TREN cap oxidation on Ln extraction for this tripodal CMPO ligand system.

X-ray crystallographic, luminescence and NMR studies of phenacyldiphenylphosphine oxide with the Ln(iii) ions Sm, Eu, Gd, Tb and Dy.

We report here the characterization in solution (NMR, luminescence, MS) and the solid-state (X-ray crystallography, IR) of complexes between phenacyldiphenylphosphine oxide and five Ln(iii) ions (Sm, Eu, Gd, Tb, Dy). Four single crystal X-ray structures are described here showing a 1 : 2 ratio between the Ln3+ ions Eu, Dy, Sm and Gd and the ligand, where the phosphine oxide ligands are bound in a monodentate manner to the metal center. A fifth structure is reported for the 1 : 2 Eu(NO3)3-ligand complex showing bidentate binding between the two ligands and the metal center. The solution coordination chemistry of these metal complexes was probed by 1H, 13C and 31P NMR, mass spectrometry, and luminescence experiments. The title ligand has the capability to sensitize Tb3+, Dy3+, Eu3+ and Sm3+ leading to metal-centered emission in solutions of acetonitrile and methanol and in the solid state.

A Prospective, Holistic, Multicenter Approach to Tracking and Understanding Bloodstream Infections in Pediatric Hematology-Oncology Patients.

OBJECTIVE To assess the burden of bloodstream infections (BSIs) among pediatric hematology-oncology (PHO) inpatients, to propose a comprehensive, all-BSI tracking approach, and to discuss how such an approach helps better inform within-center and across-center differences in CLABSI rate DESIGN Prospective cohort study SETTING US multicenter, quality-improvement, BSI prevention network PARTICIPANTS PHO centers across the United States who agreed to follow a standardized central-line-maintenance care bundle and track all BSI events and central-line days every month. METHODS Infections were categorized as CLABSI (stratified by mucosal barrier injury-related, laboratory-confirmed BSI [MBI-LCBI] versus non-MBI-LCBI) and secondary BSI, using National Healthcare Safety Network (NHSN) definitions. Single positive blood cultures (SPBCs) with NHSN defined common commensals were also tracked. RESULTS Between 2013 and 2015, 34 PHO centers reported 1,110 BSIs. Among them, 708 (63.8%) were CLABSIs, 170 (15.3%) were secondary BSIs, and 232 (20.9%) were SPBCs. Most SPBCs (75%) occurred in patients with profound neutropenia; 22% of SPBCs were viridans group streptococci. Among the CLABSIs, 51% were MBI-LCBI. Excluding SPBCs, CLABSI rates were higher (88% vs 77%) and secondary BSI rates were lower (12% vs 23%) after the NHSN updated the definition of secondary BSI (P<.001). Preliminary analyses showed across-center differences in CLABSI versus secondary BSI and between SPBC and CLABSI versus non-CLABSI rates. CONCLUSIONS Tracking all BSIs, not just CLABSIs in PHO patients, is a patient-centered, clinically relevant approach that could help better assess across-center and within-center differences in infection rates, including CLABSI. This approach enables informed decision making by healthcare providers, payors, and the public. Infect Control Hosp Epidemiol 2017;38:690-696.

Central Line Associated Blood Stream Infections in Pediatric Hematology/Oncology Patients With Different Types of Central Lines.

BACKGROUND: Central line associated bloodstream infections (CLABSIs) are a significant cause of morbidity and mortality in pediatric hematology/oncology (PHO) patients. Understanding the differences in CLABSI rates by central line (CL) type is important to inform clinical decisions. PROCEDURE: CLABSI, using similar definitions, noted with three commonly used CL types (totally implanted catheter [port], tunneled externalized catheter [TEC], peripherally inserted central catheter [PICC]) and CL-specific line days were prospectively tracked across 15 US PHO centers from May 2012 until April 2015 and CLABSI rates (CLABSI per 1,000 CL-specific line days) were calculated. Host and organism characterstics associated with the CLABSI events were analyzed. RESULTS: Over the course of 2.8 million line days, 1,113 CLABSI events (397 in inpatients and 716 in ambulatory patients) were noted. The inpatient CLABSI rate was higher than the ambulatory CLABSI rate for each of the CL types: 1.48 versus 0.16 for ports, 3.51 versus 1.38 for TECs, and 3.07 versus 1.16 for PICCs, respectively. TECs and PICCs were associated with higher CLABSI rates than ports, inpatient and ambulatory. CONCLUSIONS: We found that CLABSI rates were significantly higher for inpatients compared to ambulatory PHO patients for all CL types. Among ambulatory patients, TECs had the highest CLABSI rate and ports the lowest. Among inpatients, TECs and PICCs had higher CLABSI rates than ports but were not statistically different from one another. Cognizant that host and underlying disease attributes may contribute to these differences, these results can still inform CL choice in clinical practice.

Repellency of α-pinene against the house fly, Musca domestica.

Musca domestica L. is a non-biting nuisance fly that is capable of transmitting a large variety of pathogens to humans and non-human animals. Natural compounds and their derivatives, which are often less toxic than entirely synthetic compounds, may be used as repellents against M. domestica as part of comprehensive pest control and disease mitigation programs. This work investigates the repellent properties of the natural compound α-pinene against M. domestica. Adult house flies of both sexes avoided the volatile plant-derived terpenes (1S)-(-)-α-pinene 1 and (1R)-(+)-α-pinene 2 in constant air flow laboratory conditions, with 1 exhibiting a stronger repellent effect. House flies also avoided tarsal contact with filter paper saturated with 1. Furthermore, both 1 and 2 are electrophysiologically active on in situ female house fly antennal preparations. These findings demonstrate that α-pinene exhibits natural baseline repellency against the house fly, elicits a specific physiological response in this fly, and that functional or structural modification of 1 in particular may yield novel fly repellents with desirable properties.

Turning on lanthanide luminescence via nanoencapsulation.

Encapsulation of macrocyclic europium(III) chelates by discrete, monodisperse SiO2 nanoparticles (NPs) has been carried out, and the resulting significant enhancement of metal-derived luminescence has been studied to rationalize this dramatic effect. The tetraiminodiphenolate motif chosen for this study is easily synthesized and incorporated into the NP matrix under ambient conditions. The free complex exhibits primarily weak ligand-derived emission at room temperature, typical for these compounds, and displays intense metal-centered luminescence from the europium only when cooled to 77 K. Upon encapsulation by the NPs, however, europium-derived luminescence is visibly "turned on" at room temperature, yielding strong emission peaks characteristic of europium(III) with a corresponding enhancement factor of 6 × 10(6). The similar ligand singlet and triplet excited-state energies determined for the free complex (20820 and 17670 cm(-1), respectively) versus the encapsulated complex (20620 and 17730 cm(-1)) indicate that encapsulation does not affect the energy levels of the ligand appreciably. Instead, a detailed analysis of the metal-centered emission and ligand singlet and triplet emission bands for the free and encapsulated complexes reveals that the enhanced metal emission is due to the rigid environment afforded by the silica NP matrix affecting vibrationally mediated energy transfer. Further, the metal-centered emission lifetimes in methanol versus deuterated methanol indicate a decrease in the number of coordinated solvent molecules upon encapsulation, changing from an average of 3.3 to 2.1 bound methanol molecules and reducing the known quenching effect on europium-centered luminescence due to nearby OH vibrations.

Surveillance of hospital-acquired central line-associated bloodstream infections in pediatric hematology-oncology patients: lessons learned, challenges ahead.

Across 36 US pediatric oncology centers, 576 central line-associated bloodstream infections (CLABSIs) were reported over a 21-month period. Most infections occurred in those with leukemia and/or profound neutropenia. The contribution of viridans streptococci infections was striking. Study findings depict the contemporary epidemiology of CLABSIs in hospitalized pediatric cancer patients.

Soluble endoglin specifically binds bone morphogenetic proteins 9 and 10 via its orphan domain, inhibits blood vessel formation, and suppresses tumor growth.

Endoglin (CD105), a transmembrane protein of the transforming growth factor ß superfamily, plays a crucial role in angiogenesis. Mutations in endoglin result in the vascular defect known as hereditary hemorrhagic telangiectasia (HHT1). The soluble form of endoglin was suggested to contribute to the pathogenesis of preeclampsia. To obtain further insight into its function, we cloned, expressed, purified, and characterized the extracellular domain (ECD) of mouse and human endoglin fused to an immunoglobulin Fc domain. We found that mouse and human endoglin ECD-Fc bound directly, specifically, and with high affinity to bone morphogenetic proteins 9 and 10 (BMP9 and BMP10) in surface plasmon resonance (Biacore) and cell-based assays. We performed a function mapping analysis of the different domains of endoglin by examining their contributions to the selectivity and biological activity of the protein. The BMP9/BMP10 binding site was localized to the orphan domain of human endoglin composed of the amino acid sequence 26-359. We established that endoglin and type II receptors bind to overlapping sites on BMP9. In the in vivo chick chorioallantoic membrane assay, the mouse and the truncated human endoglin ECD-Fc both significantly reduced VEGF-induced vessel formation. Finally, murine endoglin ECD-Fc acted as an anti-angiogenic factor that decreased blood vessel sprouting in VEGF/FGF-induced angiogenesis in in vivo angioreactors and reduced the tumor burden in the colon-26 mouse tumor model. Together our findings indicate an important role of soluble endoglin ECD in the regulation of angiogenesis and highlight efficacy of endoglin-Fc as a potential anti-angiogenesis therapeutic agent.

Inhibiting activin-A signaling stimulates bone formation and prevents cancer-induced bone destruction in vivo.

Cancers that grow in bone, such as myeloma and breast cancer metastases, cause devastating osteolytic bone destruction. These cancers hijack bone remodeling by stimulating osteoclastic bone resorption and suppressing bone formation. Currently, treatment is targeted primarily at blocking bone resorption, but this approach has achieved only limited success. Stimulating osteoblastic bone formation to promote repair is a novel alternative approach. We show that a soluble activin receptor type IIA fusion protein (ActRIIA.muFc) stimulates osteoblastogenesis (p < .01), promotes bone formation (p < .01) and increases bone mass in vivo (p < .001). We show that the development of osteolytic bone lesions in mice bearing murine myeloma cells is caused by both increased resorption (p < .05) and suppression of bone formation (p < .01). ActRIIA.muFc treatment stimulates osteoblastogenesis (p < .01), prevents myeloma-induced suppression of bone formation (p < .05), blocks the development of osteolytic bone lesions (p < .05), and increases survival (p < .05). We also show, in a murine model of breast cancer bone metastasis, that ActRIIA.muFc again prevents bone destruction (p < .001) and inhibits bone metastases (p < .05). These findings show that stimulating osteoblastic bone formation with ActRIIA.muFc blocks the formation of osteolytic bone lesions and bone metastases in models of myeloma and breast cancer and paves the way for new approaches to treating this debilitating aspect of cancer.

Effect of a mesitylene-based ligand cap on the relaxometric properties of Gd(III) hydroxypyridonate MRI contrast agents.

A series of new Gd(III) hydroxypyridonate complexes featuring a mesitylene (ME)-derived ligand cap has been prepared. Relaxometric characterization reveals that the complexes tend to form large aggregates in solution with slow tumbling rates, as estimated from NMRD analysis, and unique pH-dependent relaxivities. The solution behavior and relaxometric properties are compared with those observed for analogous TREN-capped compounds, and the potential for use of these new ME-capped complexes as pH-responsive MRI contrast agents is explored.

1,2-hydroxypyridonate/terephthalamide complexes of gadolinium(III): synthesis, stability, relaxivity, and water exchange properties.

Four new Gd(III) complexes based on the 1,2-hydroxypyridinone chelator have been synthesized and evaluated as potential magentic resonance imaging contrast agents. Previously reported work examining Gd-TREN-1,2-HOPO (3; HOPO = hydroxypyridinone) suggests that the 1,2-HOPO unit binds strongly and selectively to Gd(III), encouraging further study of the stability and relaxivity properties of this class of compounds. Among the new complexes presented in this paper are the homopodal Gd-Ser-TREN-1,2-HOPO (Gd-5) and three heteropodal bis-1,2-HOPO-TAM complexes (Gd-6, Gd-7, and Gd-8; TAM = terephthalamide). Conditional stability constants were determined, and all pGd values are in the range of 18.5-19.7, comparable to other analogous HOPO complexes and currently used commercial contrast agents. Relaxivities for all complexes are about twice those of commercial agents, ranging from 7.8 to 10.5 mM(-1) s(-1) (20 MHz; 25 degrees C), and suggest two innersphere water molecules in fast exchange. Luminescent measurements were used to verify the number of coordinated waters for Gd-5, and VT (17)O NMR experiments were employed for the highly soluble Gd-TREN-bis-1,2-HOPO-TAM-N3 (Gd-8) complex to measure a fast water exchange rate, (298)k(ex) = 1/tau(M), of 5.1 (+/-0.4) x 10(8) s(-1) ((298)tau(M) approximately 2 ns).

High-relaxivity MRI contrast agents: where coordination chemistry meets medical imaging.

The desire to improve and expand the scope of clinical magnetic resonance imaging (MRI) has prompted the search for contrast agents of higher efficiency. The development of better agents requires consideration of the fundamental coordination chemistry of the gadolinium(III) ion and the parameters that affect its efficacy as a proton relaxation agent. In optimizing each parameter, other practical issues, such as solubility and in vivo toxicity, must also be addressed, making the attainment of safe, high-relaxivity agents a challenging goal. This Minireview presents recent advances in the field, with an emphasis on gadolinium(III) hydroxypyridinone chelate complexes.