北京市怀柔区儿童维生素D营养状况及其与体成分的关系

目的 分析儿童维生素D的营养状况及其与体成分的关系.方法 选取北京市怀柔区(北纬40.3°)7～11岁学龄儿童381名,于2008年3月采集静脉血并采用酶联免疫吸附试验(ELISA,英国IDS公司)测定血清中25-羟维生素D[25(OH)D]的浓度,双能X线吸收仪(DEXA,美国Norland公司)测定前臂及全身的体成分,分析维生素D与体成分的相关性.结果研究对象血清25(OH)D的平均浓度为(44.4±12.5)nmol/L,维生素D缺乏和不足率[血清25(OH)D≤50 nmol/L]达68.5%.男生血清25(OH)D浓度(46.3±13.3)nmol/L高于女生(42.0±11.1)nmol/L,差异有统计学意义(t=3.38,P<0.01).血清25(OH)D浓度与前臂近端、远端、全身及分部位中四肢的瘦体重呈正相关(r=0.13～O.19,P<0.05),与前臂近端、远端的体脂百分比呈负相关(r=-0.14,P<0.05;r=-0.11,P<0.05),均有统计学意义.调整年龄、性别、身高、体重等混杂因素后,与前臂近端、全身分部位中双下肢的瘦体重相关性仍有统计学意义(r=0.12～0.14,P<0.05).血清25(OH)D浓度与各部位体脂的相关性均无统计学意义.结论 维生素D缺乏在北京市郊区儿童中较为普遍,而维生素D营养状况对体成分,尤其对瘦体重有促进作用.     

Results of randomized controlled trials of low-versus high-osmolality contrast media

The authors reviewed 100 randomized controlled trials (RCTs) conducted in humans to compare safety or efficacy of new low-osmolality contrast media (LOM) with that of high-osmolality contrast media (HOM). Findings of the 43 RCTs judged to be of the highest quality suggest that the efficacy of LOM in imaging is equal or superior to that of HOM for all routes of administration. Heat sensation occurred less often with LOM for all routes and pain occurred less often with LOM for intraarterial routes. No differences were seen in nephrotoxicity or in frequency of nausea, vomiting, urticaria, bronchospasm, laboratory test abnormalities, or neurologic events. Greater cardiovascular changes were seen with HOM, including increased or decreased heart rate, increased left ventricular end-diastolic pressure, decreased systolic pressure, and QT prolongation, depending on route of administration. To demonstrate whether a reduction in clinically significant adverse outcomes truly occurs with LOM, trials will need to enlist larger numbers of patients and employ appropriate outcome measures. Future trials should stratify patients according to their risk of adverse reactions to provide better information about benefits of LOM in low- versus high-risk patients.     

Clonal evolution in B-lineage acute lymphoblastic leukemia by contemporaneous VH-VH gene replacements and VH-DJH gene rearrangements

B-cell acute lymphoblastic leukemia (B-ALL), more frequently than any other B-lineage neoplasm, exhibits oligoclonal Ig heavy chain (IgH) gene rearrangement in 15% to 43% of all cases studied. To study the molecular processes that promote multiple IgH rearrangements, a comprehensive sequence analysis of a B-ALL case was performed in which seven clonal IgH gene rearrangements were identified. The genetic profiles suggested that a single leukemic progenitor clone evolved into several subclones through dual processes of variable (VH) to preexisting diversity-joining (DJH) gene segment rearrangement and VH to VH gene replacement. Predominant IgH-V usage and the uniquely rearranged clonotype-specific VHDJH region gene sequences were identified using a novel DNA-based gene amplification strategy. Polymerase chain reaction (PCR) was directed by an IgH-J generic primer and a complement of family-specific IgH-V primers that defined the major B-cell IgH-V gene usage. Clonality of rearranged VHDJH bands was substantiated by high resolution denaturant gel electrophoretic analysis. Sequence patterns of the amplified VHDJH fragments segregated into two groups defined by common DJH sequences. Partial N region homology at the VHD junction as well as shared DJH sequences firmly established VH to VHDJH gene replacement as a mechanism generating clonal evolution in one group. In the second subset, oligoclonality was propagated by independent VH gene rearrangements to a common DJH precursor. The contributions of all clonal Ig-VHDJH repertoires for each group was approximately 50% and reflected a symmetric distribution of leukemic subclones generated by either process. Thus, oligoclonal rearrangements evolved by two independent, yet seemingly contemporaneous molecular genetic mechanisms. All seven clones displayed nonfunctional Ig-VHDJH recombinations. These observations may have relevance to the recombinatorial opportunities available during normal B-cell maturation.     

Heterogeneous phenotypes of platelet and plasma von Willebrand factor in obligatory heterozygotes for severe von Willebrand disease

To characterize the heterogeneity of severe (type III) von Willebrand disease (vWD), plasma and platelet von Willebrand factor antigen (vWF:Ag) and ristocetin cofactor activity (Ricof) were measured in 28 obligatory heterozygotes (ie, parents or children of probands from 15 different kindreds with severe vWD). On the average, heterozygotes had low levels of vWF in both platelets and plasma. There was, however, considerable heterogeneity, with four distinct patterns. Eleven heterozygotes had concordant reduction of vWF:Ag and Ricof in both plasma and platelets; five had low levels of vWF:Ag and Ricof in plasma contrasting with normal levels in platelets; eight had a peculiar pattern, the reverse of the above (ie, low levels in platelets and normal levels in plasma); and in one, both vWF measurements were normal in plasma and platelets. These patterns were genetically determined: they were consistent in four couples of consanguineous heterozygotes and in two couples carrying the same gene deletion. Only the remaining three heterozygotes had no clearly identifiable pattern. Other findings of this study were that although most of the heterozygotes had normal bleeding times, the 7 of 28 who had prolonged bleeding times had concordantly low levels of vWF measurements in both plasma and platelets. In conclusion, this large series of obligatory heterozygotes provides evidence for phenotypic and genotypic heterogeneity of severe vWD.     

Peripherally Inserted Central Catheter Thrombosis After Placement via Electrocardiography vs Traditional Methods

BackgroundPeripherally inserted central catheter tip placement at the cavoatrial junction is associated with reduced catheter-related deep vein thrombosis. Electrocardiographic tip confirmation purportedly improves accuracy of tip placement, but whether this approach can reduce deep vein thrombosis is unknown.MethodsProspectively collected data from patients that received peripherally inserted central catheters at 52 Michigan hospitals were analyzed. The method used to confirm tip confirmation at insertion and deep vein thrombosis outcomes were extracted from medical records. Multivariate models (accounting for the clustered nature of the data) were fitted to assess the association between peripherally inserted central catheter-related deep vein thrombosis and method of tip confirmation (electrocardiographic vs radiographic imaging).ResultsA total of 42,687 peripherally inserted central catheters (21,098 radiology vs 21,589 electrocardiographic) were included. Patients receiving electrocardiographic-confirmed peripherally inserted central catheters had fewer comorbidities compared with those that underwent placement via radiology. Overall, deep vein thrombosis occurred in 594 (1.3%) of all peripherally inserted central catheters. Larger catheter size (odds radio [OR] 1.32; 95% confidence interval [CI], 0.93-1.90 per unit increase in gauge), history of deep vein thrombosis, and cancer were associated with increased risk of deep vein thrombosis (OR 2.00; 95% CI, 1.65-2.43 and OR 1.62; 95% CI, 1.16-2.26, respectively) using logistic regression. Following adjustment, electrocardiographic guidance was associated with a significant reduction in peripherally inserted central catheter-related deep vein thrombosis compared with radiographic imaging (OR 0.74; 95% CI, 0.58-0.93; P = .0098).ConclusionThe use of electrocardiography to confirm peripherally inserted central catheter tip placement at the cavoatrial junction was associated with significantly fewer deep vein thrombosis events than radiographic imaging. Use of this approach for peripherally inserted central catheter insertion may help improve patient safety, particularly in high-risk patients.     

Clinical audits to improve critical care: Part 2: Analyse,benchmark and feedback

Clinical audits are an essential part of the cycle designed to ensure that patients receive the best quality of care. By measuring the care delivered against established best practice standards, it becomes possible to identify shortcomings and to plan targeted strategies and processes for continuous improvement. The success of a clinical audit depends upon defined goals, motivation of stakeholders, appropriate tools and resources, and clear communication.In part 1 of this series, an overview of the structures and processes needed to prepare and collect data for clinical audits in the critical care setting was provided [A.J. Ullman, G. Ray-Barruel, C.M. Rickard, M. Cooke, Clinical audits to improve critical care: Part 1 Prepare and collect data, Aust Crit Care, 2017, in press]. In part 2, we discuss how to analyse the collected audit data, benchmark findings with internal and external data sets, and feedback audit results to critical care clinicians to promote evidence-based practice and improve patient outcomes.