Characterization of human marrow stromal cells: role in progenitor cell binding and granulopoiesis

Adherent cell layers and their associated extracellular matrices form when human marrow is incubated in cultures containing hydrocortisone and horse serum. These stromal layers contain cells positive for alkaline phosphatase; secrete collagens types I and III and fibronectin, bind the anti-actin monoclonal antibodies (MoAbs) HHF and CGA-7; stain with oil red O, and express the acetylated LDL receptor. Highly purified CD34 (My10)-positive progenitor cells attach to these stromal layers, and a 16-fold enrichment of CFU-GM in both stromal attachment and semisolid agar assays was observed. Granulopoiesis persisted up to 40 days (mean duration 25 days) after passaged stroma were recharged with stromal cell-depleted target cells in a two-stage liquid marrow culture system. Although equal to marrow fibroblasts in their ability to bind CD34+ myeloid progenitors, stromal layers were better at supporting granulopoiesis. This system provides an in vitro model to characterize the components of stroma and stroma-cytomatrix that enhance marrow progenitor cell localization and maintenance.     

EPP:一个与表情特征加工相关的ERPs晚期正成分

目的 研究与表情特征加工相关的事件相关脑电位（event-related potentials，ERPs）成分。方法 被试者为12名（7男5女）右利手健康大学生。刺激包括3种卡通面孔（中性、微笑、愤怒）和3种非面孔。要求被试者进行面孔识别（face recognition，FR）和面孔表情分类（facial expression classification，FEC）2种作业。记录32导脑电。结果 1）与FR任务相比，FEC任务产生明显的P580成分；2）FEC的ERP与FR的ERP的差异波形，表现出一个非常明显的中央一顶区分布的正差异（450～850ms），命名为表性加工正成分（expression processing positivity，EPP）；3）EPP的峰值潜伏期表现出明显的表情特征主效应，以愤怒面孔EPP的潜伏期最短，微笑面孔EPP的潜伏期最长。结论 EPP可能反映了表情特征的晚期加工。     

Agreement between Emergency Physicians and Psychiatrists Regarding Admission Decisions

Objective: To determine the level of agreement between emergency physicians (EPs) and psychiatrists regarding the need for acute psychiatric hospitalization and treatment for patients presenting with alleged psychiatric complaints.
Methods: A prospective, cross-sectional assessment of concordance between EPs and psychiatrists in psychiatric admission decisions was performed at an urban county, teaching hospital ED. The participants had been brought to the ED for psychiatric evaluation. The patients were interviewed by an attending EP or a senior-level resident, and a tentative impression and disposition were determined pfior to an independent examination and final disposition by a psychiatrist. Strength of physician group agrement was determined using the k statistic.
Results: The patient mean age was 37.5 ± 15 years; 51% were men. The most common reasons for evaluation were disruptive behavior (28%), overdose (24%), and danger to self (23%). Of the 156 patients, 47 (28.7%) were sent home without treatment, 10 (6.3%) were determined to need only medical treatment, and 6 (3.7%) were released with outpatient psychiatric treatment. There were 84 (55.7%) patients admitted for psychiatric treatment. The EPs and psychiatrists had only moderate agreement regarding danger to self (k = 0.44), danger to others (k = 0.40). substance abuse as the primary problem (k = 0.50), and need for psychiatric hospitalization (k = 0.54).
Conclusion: Moderate agreement between EPs and psychiatrists in key impressions and admission decisions suggests that shared training in psychiatric decision making, especially during residency training, is desired in this setting.     

Methodological challenges to control for immortal time bias in addressing drug effects in type 2 diabetes

There are multiple biases in using observational studies to examine treatment effects such as those from prevalent drug users, immortal time and drug indications. We used renin angiotensin system (RAS) inhibitors and statins as reference drugs with proven efficacies in randomized clinical trials (RCTs) and examined their effectiveness in the prospective Hong Kong Diabetes Registry using adjustment methods proposed in the literature. Using time-dependent exposures to drug treatments yielded greatly inflated hazard ratios (HR) regarding the treatment effects of these drugs for cardiovascular disease (CVD) in type 2 diabetes. These errors were probably due to changing indications to use these drugs during follow up periods, especially at the time of drug commencement making time-dependent analysis extremely problematic. Using time-fixed analysis with exclusion of immortal time and adjustment for confounders at baseline and/or during follow-up periods, the HR of RAS inhibitors for CVD was comparable to that in RCT. The result supported the use of the Registry for performing pharmacoepidemiological analysis which revealed an attenuated low low-density lipoprotein cholesterol related cancer risk with RAS inhibitors. On the other hand, time-fixed analysis with including immortal time and adjustment for confounders at baseline and/or during follow-up periods, the HR of statins for CVD was similar to that in the RCT. Our results highlight the complexity and difficulty in removing these biases. We call for validations of the methods to cope with immortal time and drug use indications before applying them to particular research questions, so to avoid making erroneous conclusions.     

Resolvin D1 controls inflammation initiated by glutathione-lipid conjugates formed during oxidative stress

Background and purpose:

Inflammation is associated with oxidative stress and local generation of lipid peroxidation-derived aldehydes, such as 4-hydroxy-trans-2-nonenal (HNE). In most tissues, HNE is readily conjugated with glutathione and presently it is unknown whether glutathionyl-HNE (GS-HNE) plays a functional role in inflammation. Here, we sought to determine whether GS-HNE is a mediator of oxidative stress-initiated inflammation and if its actions can be regulated by the anti-inflammatory and pro-resolving lipid mediator, resolvin D1 (RvD1).

Experimental approach:

GS-HNE was administered intraperitoneally to mice and peritoneal lavages were assessed for leukocyte infiltration and lipid mediators were targeted by mediator-lipidomics. RvD1 was administered to mice treated with GS-HNE and leukocyte infiltration was assessed in the peritoneum. Superoxide production and CD11b modulation were measured in isolated human polymorphonuclear leukocytes incubated with GS-HNE.

Key results:

GS-HNE (1–10 µg) evoked infiltration of Gr-1⁺ leukocytes into the peritoneum to form an inflammatory exudate. With isolated human polymorphonuclear leukocytes, GS-HNE stimulated both superoxide generation and CD11b expression. Among the lipid mediators, both cyclooxygenase- and lipoxygenase-derived pro-inflammatory eicosanoids, including prostaglandin E₂, leukotriene B₄ and cysteinyl leukotrienes, were generated in exudates of mice injected intraperitoneally with GS-HNE. RvD1, given i.v. in doses as low as 0.01–10.0 ng, sharply reduced GS-HNE-stimulated leukocyte infiltration (∼30–70%).

Conclusions and implications:

Glutathione conjugates of HNE, derived during oxidative stress, are pro-inflammatory in vivo. RvD1 protects against this oxidative stress-initiated inflammation.This article is part of a themed issue on Mediators and Receptors in the Resolution of Inflammation. To view this issue visit http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009