Root cause analysis of limitations of virtual crossmatch for kidney allocation to highly-sensitized patients

Efficient allocation of deceased donor organs depends upon effective prediction of immunologic compatibility based on donor HLA genotype and recipient alloantibody profile, referred to as virtual crossmatching (VCXM). VCXM has demonstrated utility in predicting compatibility, though there is reduced efficacy for patients highly sensitized against allogeneic HLA antigens. The recently revised deceased donor kidney allocation system (KAS) has increased transplantation for this group, but with an increased burden for histocompatibility testing and organ sharing. Given the limitations of VCXM, we hypothesized that increased organ offers for highly-sensitized patients could result in a concomitant increase in offers rejected due to unexpectedly positive crossmatch. Review of 645 crossmatches performed for deceased donor kidney transplantation at our center did not reveal a significant increase in positive crossmatches following KAS implementation. Positive crossmatches not predicted by VCXM were concentrated among highly-sensitized patients. Root cause analysis of VCXM failures identified technical limitations of anti-HLA antibody testing as the most significant contributor to VCXM error. Contributions of technical limitations including additive/synergistic antibody effects, prozone phenomenon, and antigens not represented in standard testing panels, were evaluated by retrospective testing. These data provide insight into the limitations of VCXM, particularly those affecting allocation of kidneys to highly-sensitized patients.     

Analysis of ischemic cerebral lesions using 3.0-T diffusion-weighted imaging and magnetic resonance angiography after revascularization surgery for ischemic disease

Background

Cerebral revascularization surgery (CRS) is increasingly recognized as an important component in the treatment of complex cerebral vascular disease and tumors. CRS requires that the incidence of perioperative neurological complications should be minimized, because CRS for ischemic disease is often not the goal of treatment, but rather a prophylactic surgery. CRS carries the risk of focal postoperative neurological deficits. Little has been established concerning mechanisms of post-CRS ischemia. We used 3.0-T diffusion-weighted magnetic resonance imaging (DWI) and magnetic resonance angiography (MRA) to analyze the incidence and mechanism of ischemic lesions.

Methods

We studied the anterior circulation territory after 20 CRS procedures involving 33 vascular anastomosis procedures (13 double anastomoses and 7 single anastomoses) in 12 men and 8 women between June 2007 and October 2011. The operations included single or double superficial temporal artery–middle cerebral artery (STA–MCA) anastomosis to treat internal carotid artery/MCA occlusions or severe MCA stenosis. A combined STA–MCA anastomosis and indirect bypass were performed for moyamoya disease. Postoperative DWI and MRA were obtained in all patients between 24 and 96 h after surgery to detect thromboembolism, hypoperfusion, or procedural ischemic complications and vasospasms of the donor STA.

Results

Follow-up DWI and MRA were carried out 1.8 ± 0.6 days after CRS (range, 1–4 days). Temporary occlusion time for anastomoses averaged 18.9 min (range, 16–32 min). Asymptomatic new hyperintensities occurred in the ipsilateral hemisphere of 2 patients on postoperative DWI (10% patients/6.0% anastomoses), and 1 moyamoya patient (5.0% patients/3.0% anastomoses) developed a symptomatic hyperintensity in the ipsilateral occipital lobe in response to the operation. Two abnormal small (<5 mm) cortical DWI lesions were caused by sacrifices of a small branch of the recipient MCA.

Conclusion

This study is the first postoperative 3.0-T DWI study of CRS and related clinical events. The incidence of symptomatic postoperative DWI abnormalities was restricted to 1 moyamoya patient representing 5.0% of total patients and 3.0% anastomoses. Although some postoperative DWI abnormalities occurred, CRS was found to be safe with a low risk of symptomatic ischemia.     

MCS: the status of population-based research

MCS has been studied predominantly in clinical and occupational settings. Since the mid-1990's, a few investigators have examined dimensions of this controversial syndrome in the general population. In this discussion, the role of epidemiology in learning about MCS is presented. Some of the challenges of population-based research on MCS are discussed. Specific studies are presented with regard to study population, case definition, exposure and case classification methods, interpretation, and conclusions.     

An open-label study of quetiapine in the treatment of fibromyalgia

The aim of this exploratory study was to systematically assess the potential effectiveness and tolerability of quetiapine, an atypical antipsychotic, for the treatment of patients with fibromyalgia. This was a unicentre, open-label study conducted in thirty-five outpatients, 18 years or older, who met the ACR criteria for fibromyalgia and who had not satisfactorily responded to their previous fibromyalgia treatment. Quetiapine, flexibly dosed (25-100 mg/day), was added to their original treatment regimen for 12 weeks. The primary outcome measure was the mean change from baseline to endpoint in the Fibromyalgia Impact Questionnaire (FIQ) total score. Secondary efficacy measures included mean changes from baseline to endpoint in the scores of the Clinical Global Impression (CGI) of Severity scale, Pittsburgh Sleep Quality Index (PSQI), Beck Depression Inventory (BDI), State-Trait Anxiety Inventory (STAI), 12-Item Short Form Health Survey (SF-12), and individual items of the FIQ. Thirty (85.7%) patients (mean age 47+/-7.9, 93.3% females) had a postbaseline evaluation and constituted the intent-to-treat efficacy sample. Mean FIQ total score decreased significantly by 10.2 points from a baseline of 63.2 to 53.0 at study endpoint (p<0.001). A statistically significant reduction was observed in FIQ stiffness and FIQ fatigue subscores but not in FIQ pain subscore. Large effect sizes were observed for the FIQ total (1.04), CGI-severity (1.00) and PSQI (1.07), while moderate effect sizes (i.e.> or =0.50) were encountered in the FIQ fatigue, FIQ stiffness and SF-12 mental component summary. Quetiapine was safely administered and well tolerated. Despite the lack of effect on pain, the significant and relevant improvement in overall efficacy measures and quality of life suggests that quetiapine may be a valuable drug for treatment of patients with fibromyalgia that should be further tested in double-blind, placebo-controlled trials.     

近红外光谱分析中光谱预处理方法的作用及其发展

光谱预处埋方法在近红外(NIR)光谱分析技术中具有非常重要的作用。本文综述了常用的 NIR 光谱预处理方法及最新发展的几种预处理方法的原理及作用,并给出了这些方法的一些应用实例。重点分析平滑处理(smoothing)、多元散射校正(MSC)、标准正态变量校正(SNV)等常用光谱预处理方法的利弊,详细介绍小波变换(WT)、正交信号校正(OSC)等新光谱预处理方法。     

Universal monoclonal antibody-based influenza hemagglutinin quantitative enzyme-linked immunosorbent assay

Seasonal and pandemic influenza infections remain a serious public health concern. Many health authorities recommend annual vaccination as the most effective way to control influenza infection. Accordingly, regulatory guidelines ask vaccine manufacturers to determine vaccine potency at the time of release and throughout shelf-life to ensure vaccine quality. The potency of inactivated influenza vaccine is related to the quantity of hemagglutinin (HA). Since 1970s, single radial immunodiffusion (SRID) assay has been standardly used for the quantitation of HA in influenza vaccine. However, SRID is labor-intensive, inaccurate, and requires standard reference reagents that should be updated annually. Therefore, there have been extensive efforts to develop alternative potency assays. In this study, we developed and tested a new HA quantitative enzyme-linked immunosorbent assay (ELISA) using a universal monoclonal antibody that can bind to HAs from various subtypes in group 1 influenza A virus (IAV). We analyzed the conserved stalk domain of HA via a library approach to design a consensus HA antigen for group 1 IAV. The antigens were expressed as a soluble form in E. coli and were purified by Ni-affinity chromatography. When tested with variety of HAs from IAVs or influenza B viruses (IBVs), the mAbs exhibited specific binding to group 1 HAs, with potential exception to H9 subtype. Among various conditions of pH, urea, and reducing agents, pretreatment of HA at low pH exposing the conserved stalk domain was crucially important for optimal ELISA performance. Calibration curves for various HAs were generated to determine accuracy, specificity, sensitivity, and linear dynamic range. The ELISA method shows high sensitivity and accuracy compared with the SRID assay. The HA group specific universal mAbs against the consensus stalk domain of HA are conducive to establishing an ELISA-based standard procedure for the quantitation of HA antigens for annual vaccination against influenza infection.     

Symptomatology and Etiology of Multiple Chemical Sensitivities in the Southeastern United States

A questionnaire was administered to individuals who had reported a hypersensitivity to common chemical products in an earlier epidemiological study in the Atlanta, Georgia, metropolitan area. The questionnaire investigated the nature of the symptoms and factors that potentially initiated hypersensitivity and subsequently triggered reactions. Also examined were associated lifestyle modifications and the relationships of hypersensitivity with other illnesses. The authors found that a majority of hypersensitive individuals (52.2%) experienced either “severe” or “somewhat severe” symptoms. The most common triggers of symptoms were cleaning products (88.4%), tobacco smoke (82.6%), perfume (81.2%), pesticides (81.2%), and car exhaust (72.5%). Only 1.4% of the subjects had a prior history of emotional problems, whereas 37.7% developed such problems after the emergence of their hypersensitivity. Lifestyle modifications varied; 76.8% changed their household cleaning/personal hygiene products, 47.8% began using water and/or air filtration systems, and 13% found it necessary to change residence. Although hypersensitivity was more common in females than males, the condition affects individuals in all categories of race/ethnicity, age, household income, and educational level.