Enhanced metabolism of 1-beta-D-arabinofuranosylcytosine in Down syndrome cells: a contributing factor to the superior event free survival of Down syndrome children with acute myeloid leukemia

Down syndrome (DS) children with acute myeloid leukemia (AML) have significantly higher event-free survival (EFS) rates compared with non- DS children when treated with protocols containing 1-beta-D- arabinofuranosylcytosine (ara-C). Sensitivity and metabolism of ara-C was examined in myeloblasts from DS and non-DS patients with AML, DS infants with the transient myeloproliferative disorder, and Epstein- Barr Virus (EBV) transformed lymphoblastoid cell lines with and without trisomy 21. DS myeloblasts were approximately 10-fold more sensitive to ara-C (measured by the 3-[4,5-dimethyl-thiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) colorimetric sensitivity assay), compared with non-DS myeloblasts, following exposure to ara-C for 72 hours. Mean levels of l-beta-D-arabinofuranosylcytosine 5'-triphosphate (ara-CTP) were significantly higher in DS myeloblasts compared with non-DS myeloblasts after incubation with 5 micromol/L ara-C (621.4 v 228.4 pmol/mg protein). DS cell lines also generated higher levels of ara-CTP compared with cell lines with diploid chromosome numbers (66.5 v 13.6 pmol/mg protein and 137.6 v 41.7 pmol/mg protein at 1 and 5 micromol/L ara-C, respectively). Elevated ara-CTP levels in the DS cells were accompanied by slightly lower levels of endogenous deoxycytidine triphosphate (dCTP) pools, slightly greater extent of ara-C incorporation into DNA, and increased relative numbers of double strand DNA strand breaks. There were no significant differences in the cell cycle distributions of DS and non-DS cells. These in vitro studies support our hypothesis that enhanced metabolism of ara-C in DS cells may be a contributing factor to the superior survival rate of DS children with AML and is possibly based on a gene dosage effect of genes localized to chromosome 21 including cystathionine-beta-synthase. Further study of the mechanisms (ie, alterations in dCTP pools and DNA methylation) involved may lead to improvements in the treatment of all AML patients.     

北野菊黄酮类成分研究

从北野菊(Dendranthema lavandulifolium)全草中分得四个黄酮类化合物。经光谱(UV,IR,氢谱,碳谱,质谱等)方法鉴定其结构,分别为木樨草素(I),洋芹素(I),金合欢素-7-O-α-L-鼠李糖基(1→6)-β-D-葡萄糖甙(II)和金合欢素-7-O-α-L-鼠李糖基(1→6)-[2-O-乙酰基-β-D-葡萄糖基(1→2)]-β-D-葡萄糖甙(IV)。其中,I和I为首次从该植物中得到,IV为一个新化合物。     

Radiology interventions in patients receiving low molecular weight heparin: Timing is critical

Recent advances in diagnosis and treatment of venous thromboembolism have been associated with increasing use of low molecular weight heparins (LMWH) for treatment and prophylaxis of this disease. Despite this trend for more widespread use of LMWH, little is known of their safety in patients undergoing radiology interventions. Differences between LMWH and unfractionated heparin and the implications of these differences on use of LMWH in the setting of radiological interventions are outlined.     

Fulfilling regional needs for specialty nurses through limited-cohort graduate education

The University of Minnesota has developed a limited-cohort distance education graduate program to overcome geographic barriers and address the shortage of master's-prepared specialty nurses in rural areas of the upper Midwest. Such a program offers graduate nursing education in various specialty areas to distance sites for a predetermined, relatively short period.     

In situ imaging and impedance measurements of titanium surfaces using AFM and SPIS

Surfaces of commercially pure titanium and titanium, 6-aluminum, 4-vanadium were subjected to simultaneous polarization/impedance testing and in situ electrochemical atomic force microscopy imaging to evaluate how the structure and properties of the passive oxide film is affected by varying potential and hydration. Current transients were acquired via a step polarization impedance spectroscopy technique: the voltage was stepped between -1 and 1 V in 50 mV increments, while current transients and surface morphology were digitally recorded. Numerical Laplace transformation applied to the current transient data provided frequency-dependent admittance (impedance(-1)). Simultaneous AFM imaging of dry surfaces, initially hydrated surfaces, and surfaces immersed and changing with potential revealed that all sample surfaces were covered with protective titanium oxide domes that grew in area and coalesced due to hydration and as a function of increasing applied voltage and time. Reversal of dome growth did not occur upon voltage reduction, while impedance behavior was quasi-reversible, suggesting independence between structural and electrical properties. Oxide growth appeared to occur in part by lateral spreading and overgrowth of domes at the oxide-solution interface. Interfacial impedance data reflect oxide passivity and n-type semiconductor behavior. Non-linear Mott-Schottky fits specified multi-layer donor concentrations between 10(18) and 10(19)cm(-3), depending on the surface.     

氧瓶燃烧-紫外分光光度法测定硒灵胶囊中硒的含量

目的：控制本品中硒的含量。方法：采用氧瓶燃烧法使本样品中的主要成份硒酯多糖成四阶硒离子,并与２,３－二氨基萘（ＤＮＡ）络合生成４,５－苄苯并硒二唑,然后采用紫外分光光度法测定其含量,结果：硒的浓度在０．２～２．０μｇ／ｍｌ之间线性范围良好。结论：该法具有简便,快速,准确的优点。     

Effect of hydrogen peroxide on titanium surfaces: in situ imaging and step-polarization impedance spectroscopy of commercially pure titanium and titanium, 6-aluminum, 4-vanadium

To analyze titanium's response to representative surgical wound environments, a study was conducted on commercially pure titanium (CPTi) and titanium, 6-aluminum, 4-vanadium (Ti-6Al-4V) exposed to phosphate-buffered saline (PBS) with 30 mM of hydrogen peroxide (H(2)O(2)) added. The study was characterized by simultaneous electrochemical atomic force microscopy (EC AFM) and step-polarization impedance spectroscopy (SPIS). Surfaces were covered with protective oxide domes that indicated topography changes with potential and time of immersion. Less oxide dome coarsening was noted on surfaces treated with PBS containing H(2)O(2) than on surfaces exposed to pure PBS. Electrical data deduced from current transients collected while stepping voltage between 0 V and 1 V indicated that charge transfer in hydrogen peroxide solutions was an order of magnitude larger than it was in pure PBS. Oxide (early) resistances of CPTi samples were higher than were Ti-6Al-4V oxide resistances in both types of solutions, but CPTi oxide resistance was lower in the hydrogen peroxide solution compared to pure PBS. Capacitance data suggest that CPTi oxide films thicken in hydrogen peroxide solution more than they do in pure PBS. Differences in electrical properties between CPTi and Ti-6Al-4V surfaces suggest that CPTi, but not Ti-6Al-4V, has catalytic activity on H(2)O(2) and that the catalytic activity of CPTi oxide affects its ability to grow TiO(2). Differences in electrical properties are related to catalytic and oxidative mechanisms that take place directly on the titanium oxide surface and in wound environments. The study provides a foundation and theoretic basis for the porous oxide model on commercially pure titanium exposed to hydrogen peroxide.     

Technology assessment: relationship to coverage issues--a case for temporary coverage decisions

Making appropriate coverage decisions has the potential of impacting patient outcomes. In both the public and private sectors, great diversity exists in the methodology and process used to make coverage decisions. Because definitional issues are important, they are described in this article. The underpinning of coverage decisions are a commitment to certain methodological principles, including embracing evidence-based medicine. The role of the federal government and local entities in regard to evidence production and process as well as methodology used to formulate policy decisions is complex and requires resolution. A temporary coverage decision can be a helpful tool when no consensus exists.