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.     

Corrosion of lead shielding in a radiology department

Corrosion of lead sheet used for structural radiation protection in the Princess Alexandra Hospital radiology department has been identified. The corrosion is thought to have been caused by organic acid vapours released from oregon timber wall panelling. Non-destructive testing (NDT) and X-ray transmission measurements were used to define the extent and severity of damage, and subsequently to provide the data necessary for estimation of staff and public radiation doses. Although radiation dose limits have not been exceeded, corrective actions including structural modifications and staff information sessions have been undertaken.     

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.     

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。     

NEW ADVANCES IN THE MOLECULAR BIOLOGY OF ISCHEMIA/REPERFUSION: MAPK PATHWAYS

Elevated levels of intact parathyroid hormone (iPTH) are not uncommon after renal transplantation, and this disturbance may affect renal allograft function. This study investigated whether iPTH levels were related to histopathological findings of acute rejection in kidney graft biopsies. Thirty-eight renal transplant recipients (29 males, nine females; mean age 29.5±10.3years) were studied. Renal allograft biopsy was performed in each case to investigate increased creatinine levels. Lymphocyte and macrophage infiltration of the interstitium was evaluated immunohistochemically with monoclonal antibodies to CD3 and CD68. Expression of HLA-DR and fibronectin were also studied. The proportion of interstitial cell staining was graded semiquantitatively. Serum calcium, phosphorus and iPTH levels before and after the renal transplantation were compared. Patients were grouped according to their stabilized iPTH levels at 3 months post-transplantation. Group I ( n =13) exhibited persistently elevated iPTH levels (levels elevated since surgery), and Group II ( n =25) showed persistently low-normal iPTH levels. The mean age of the Group I patients was significantly lower, and their serum calcium levels post-transplantation were significantly higher than those in Group II ( P =0.02 and P =0.03, respectively). Persistent elevation of iPTH was strongly associated with interstitial T-cell density, macrophage density, and glomerular fibronectin expression in the renal allograft biopsies ( P <0.05). Also, the time to fibrosis was significantly shorter in Group I ( P =0.02). The study revealed that PTH has a potent immunomodulatory effect, and that persistent hyperparathyroidism has a significant impact on renal allograft outcome. The data indicate that the serum iPTH level is a valuable indicator of immune response, and that regular monitoring of serum iPTH levels is essential after renal transplantation.     

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.     

五味子醇甲类似物的全合成

五味子醇甲类似物9是五味子醇甲的代谢产物之一。本文以没食子酸为原料,经甲基化,Henry缩合、还原和分子间还原偶合等六步反应得到了具有苏、赤式两种构型的中间体7,再经DDQ作试剂的非酚氧化偶合反应完成了化合物9的全合成。同时得到另一新化合物10,并对两种产物的生成机制作了探讨。药理结果表明:化合物9具有与五味子醇甲相当的抗惊活性.     

Telephone transmission of radiographic images

A new system for telecommunication of radiographic images using readily available telephone transmission circuitry is described. The resulting video images were satisfactory for accurate interpretation in 80% of the cases tested. The system is moderately priced and has facilitated maintenance of radiodiagnostic interpretive services at a satellite office form the central hospital location.