Promoting active learning through on-line discussion boards

The authors describe faculty experiences in developing and evaluating on-line discussion boards for an undergraduate nursing program. The advantages and limitations of on-line discussions as well as various applications of the methodology are presented. A variety of innovative applications for on-line discussions in undergraduate didactic and clinically based nursing courses are illustrated.     

Validating self-reported strokes in a longitudinal UK cohort study (Whitehall II): Extracting information from hospital medical records versus the Hospital Episode Statistics database

Background

Quantiles are a staple of epidemiologic research: in contemporary epidemiologic practice, continuous variables are typically categorized into tertiles, quartiles and quintiles as a means to illustrate the relationship between a continuous exposure and a binary outcome.

Discussion

In this paper we argue that this approach is highly problematic and present several potential alternatives. We also discuss the perceived drawbacks of these newer statistical methods and the possible reasons for their slow adoption by epidemiologists.

Summary

The use of quantiles is often inadequate for epidemiologic research with continuous variables.     

Replication-timing boundaries facilitate cell-type and species-specific regulation of a rearranged human chromosome in mouse

In multicellular organisms, developmental changes to replication timing occur in 400-800 kb domains across half the genome. While examples of epigenetic control of replication timing have been described, a role for DNA sequence in mammalian replication-timing regulation has not been substantiated. To assess the role of DNA sequences in directing developmental changes to replication timing, we profiled replication timing in mice carrying a genetically rearranged Human Chromosome 21 (Hsa21). In two distinct mouse cell types, Hsa21 sequences maintained human-specific replication timing, except at points of Hsa21 rearrangement. Changes in replication timing at rearrangements extended up to 900 kb and consistently reconciled with the wild-type replication pattern at developmental boundaries of replication-timing domains. Our results are consistent with DNA sequence-driven regulation of Hsa21 replication timing during development and provide evidence that mammalian chromosomes consist of multiple independent units of replication-timing regulation.     

后型尿道下裂二期膀胱黏膜半管状重建尿道术的临床研究

目的探讨采用二期膀胱黏膜半管状重建尿道术治疗后型尿道下裂的临床研究。方法81例后型尿道下裂病例采用二期手术：一期手术将阴茎海绵体完全伸直,阴茎包皮内板和背侧皮肤预置于阴茎腹侧;二期手术采用半管状阴茎阴囊皮肤＋半管状膀胱黏膜成形尿道术。结果81例后型尿道下裂患者矫形后形态几乎接近正常。手术成功率为86．4％（70／81）,尿瘘发生率为13．6％（11／81）,8例（9．9％,8／81）发生尿道狭窄,经尿道扩张治疗后痊愈。结论二期膀胱黏膜半管状重建尿道术治疗后型尿道下裂的手术成功率较高,值得临床推荐。     

恶性肿瘤中Yap和survivin表达关联研究进展

在恶性肿瘤的发生与发展过程中,肿瘤凋亡抑制因子IAP家族和对其有激活作用的Hippo通路因子起着非常重要作用,以及其重要因子YAP和Survivin在恶性肿瘤的相互作用研究被很多研究者所注目。二者关联的研究可能为临床寻找有效治疗恶性肿瘤的方案提供新的思路。     

Chondrocytes and bone marrow-derived mesenchymal stem cells undergoing chondrogenesis in agarose hydrogels of solid and channelled architectures respond differentially to dynamic culture conditions

The objective of this study was to investigate how a combination of different scaffold architectures and rotational culture would influence the functional properties of thick cartilaginous tissues engineered using either chondrocytes or bone marrow-derived mesenchymal stem cells (BM-MSCs). Expanded porcine chondrocytes and BM-MSCs were suspended in 2% agarose and cast in custom-designed moulds to produce either regular solid or channelled construct cylinders. The study consisted of three seperate experimental arms. First, chondrocyte and BM-MSC constructs were cultured in free swelling conditions for 9 weeks. Second, constructs were subjected to rotational culture for a period of 3 weeks. Finally, BM-MSC-seeded constructs were subjected to delayed rotational culture, in which constructs were first cultured for 3 weeks in free swelling conditions, followed by an additional 3 weeks in rotating culture conditions. Constructs were supplemented with TGFβ3 during the first 3 weeks of all experiments. The introduction of channels alone had little effect on the spatial patterns of tissue accumulation in either chondrocyte- or BM-MSC-seeded constructs. The two cell types responded differentially to rotational culture, resulting in the formation of a more homogeneous tissue in chondrocyte-seeded constructs, but significantly inhibiting chondrogenesis of BM-MSCs. This inhibition of chondrogenesis in response to dynamic culture conditions was not observed if BM-MSC-seeded constructs were first maintained in free swelling conditions for 3 weeks prior to rotation. The results of this study demonstrate that bioreactor culture conditions that are beneficial for chondrocyte-based cartilage tissue engineering may be suboptimal for BM-MSCs.     

Codon optimization of human factor VIII cDNAs leads to high-level expression

Gene therapy for hemophilia A would be facilitated by development of smaller expression cassettes encoding factor VIII (FVIII), which demonstrate improved biosynthesis and/or enhanced biologic properties. B domain deleted (BDD) FVIII retains full procoagulant function and is expressed at higher levels than wild-type FVIII. However, a partial BDD FVIII, leaving an N-terminal 226 amino acid stretch (N6), increases in vitro secretion of FVIII tenfold compared with BDD-FVIII. In this study, we tested various BDD constructs in the context of either wild-type or codon-optimized cDNA sequences expressed under control of the strong, ubiquitous Spleen Focus Forming Virus promoter within a self-inactivating HIV-based lentiviral vector. Transduced 293T cells in vitro demonstrated detectable FVIII activity. Hemophilic mice treated with lentiviral vectors showed expression of FVIII activity and phenotypic correction sustained over 250 days. Importantly, codon-optimized constructs achieved an unprecedented 29- to 44-fold increase in expression, yielding more than 200% normal human FVIII levels. Addition of B domain sequences to BDD-FVIII did not significantly increase in vivo expression. These significant findings demonstrate that shorter FVIII constructs that can be more easily accommodated in viral vectors can result in increased therapeutic efficacy and may deliver effective gene therapy for hemophilia A.