Storage of Gamma-Glutamyltransferase from Dried Serum Spots: Matrix for Field Based Studies

Background: Gamma-glutamyltransferase is recognised as a biomarker to assess the harms associated with alcohol misuse. The objective ways to measure GGT in areas lacking central lab facilities are desirable. This study aims to measure GGT from dried serum spots and its storage from dried serum spots. Method: The study was approved by the institutional ethical committee. One hundred and eighty (180) patients were included in the study. Their blood samples were collected. The serum samples were spotted onto filter paper (Whatman 903) dried and stored at 4°C. The GGT levels were measured on the day of collection and at various time periods to assess the effect of storage. All the analysis was performed on SPSS version 21. Result: The GGT levels measured from fresh serum GGT levels mean (SD) 286.5 (539.4) correlated well with their respective dried serum levels 287.18 (538.2) (P = 0.80). The mean recovery of GGT from dried serum was observed to be 103.3%. A sub-sample (n = 12) was stored at 4°C. The dried serum spots were found to be stable at the end of four weeks using repeated measure analysis of variance (ANOVA) (P = 0.39). Conclusion: This method has the potential to be used for epidemiological or field based studies to assess harms associated with alcohol use.

干斑法保存血浆中HBV、HCV、HIV病毒核酸及其保存效期研究

目的:建立一种以干斑法为基础制作的血液采集卡保存血浆中病毒核酸的方法,通过建立阿伦尼乌斯方程,预测该种保存方法保存核酸的效期,并论证该种保存方法在血站留存血液样本进行核酸复测的可行性。方法:分别将HBV、HCV、HIV核酸阳性的血浆样本制备成保存卡,以干浆斑的形式进行保存;将制备的保存卡分别放置于37、45、50和55℃条件下进行加速保存实验,不定期取出各个温度条件下的保存卡片,进行核酸提取操作,纯化出待测核酸样本,进行后续PCR测试,并记录CT值;根据阿伦尼乌斯方程建立起失效时间与储存温度之间的模型,进而推测出血液采集卡在规定保存温度条件下保存核酸的有效期。结果:HBV、HCV、HIV 3种核酸阳性的血浆样本,在使用干斑法保存时,其保存效期与温度的回归方程分别为:y=-11546x+31.74、y=-12949x+36.88、y=-12204x+34.48,线性回归的相关系数r均>0.98。预测HBV、HCV和HIV 3种病毒核酸使用干斑法保存时,在4℃的保存温度下,其保存效期分别为20792、19289和14285 d;在20℃的保存温度下,保存效期分别为2135、1502和1289 d。结论:血液样本中常见的3种病毒核酸,使用干斑法保存时,在加速破坏实验中符合一级反应模式,核酸降解速度与保存的绝对温度之间的关系符合阿伦尼乌斯方程。经过该方程的推算,使用干斑法保存血浆核酸样本,在不高于20℃的保存条件下,核酸稳定性效期最低可达3.5年,基本可满足血站血液样本留样保存年限的要求。

高导热环氧复合材料干式电抗器热点温升的仿真研究

干式电抗器的稳定运行影响新型电力系统的输电可靠性。干式空心电抗器包封材料整体由浸有环氧树脂的玻璃纤维丝经高温固化而成。本文采用多物理场耦合有限元方法,考虑干式空心电抗器的包封材料热导率对其热点温升的影响,建立了环氧复合材料的COMSOL微观仿真模型和外电路约束下的干式空心电抗器电-磁、流-热耦合计算模型。将电磁场下的损耗作为热源计算温度场与流场分布,研究在25℃环境温度下常规/高导热环氧复合材料对干式空心电抗器热点温升的影响规律。结果表明:高导热环氧树脂对复合材料热导率的提升效果显著;包封材料本体及周围空气温度场区域中热点温升最大值为103.75℃,出现在内部第4层包封材料的上端处;不同热导率的复合材料对降低干式电抗器的热点温升有明显差异,其中干式电抗器在高导热环氧树脂复合材料下的热点温度降低了7.55℃。

Dried blood spots,valid screening for viral hepatitis and human immunodeficiency virus in real-life

AIM To detect chronic hepatitis B(CHB),chronic hepatitis C(CHC) and human immunodeficiency virus(HIV) infections in dried blood spot(DBS) and compare these samples to venous blood sampling in real-life.METHODS We included prospective patients with known viral infections from drug treatment centers,a prison and outpatient clinics and included blood donors as negative controls. Five drops of finger capillary blood were spotted on filter paper,and a venous blood sample was obtained. The samples were analyzed for HBs Ag,antiHBc,anti-HBs,anti-HCV,and anti-HIV levels as well as subjected to a combined nucleic acid test(NAT) for HBV DNA,HCV RNA and HIV RNA.RESULTS Samples from 404 subjects were screened(85 CHB,116 CHC,114 HIV and 99 blood donors). DBS had a sensitivity of > 96% and a specificity of > 98% for the detection of all three infections. NAT testing did not improve sensitivity,but correctly classified 95% of the anti-HCV-positive patients with chronic and past infections. Anti-HBc and anti-HBS showed low sensitivity in DBS(68% and 42%).CONCLUSION DBS sampling,combined with an automated analysis system,is a feasible screening method to diagnose chronic viral hepatitis and HIV infections outside of the health care system.

LC–HRMS determination of piperine on rat dried blood spots: A pharmacokinetic study

A liquid chromatography-high resolution mass spectrometry （LC-HRMS） method was developed and validated for the determination of piperine （PPR） on dried blood spots （DBS）. DBS samples were prepared by spiking the whole blood with analyte to produce 30 μL of blood spots on specimen collection cards. Chromatographic separation was achieved on an Atlantis dC18 column using acetonitrile and water （0.1% formic acid） （85：15, v/v） as mobile phase in an isocratic mode of elution at a flow rate of 0.75 mL/min. MS detection was carried out in electrospray positive ion mode for the target ions and monitored at m/z 286.1465 for PPR and 272.1303 for the internal standard （IS）. The developed method exhibited a linear dynamic range over 0.01-2000 ng/mL for PPR on DBS. The overall extraction recovery of PPR from DBS was 92.5%. Influence of hematocrit and spot volume on DBS was also evaluated and found to be well within the acceptable limits. The method was successfully applied to pharmacokinetic studies of PPR in rats.

Potential use of a dried saliva spot(DSS)in therapeutic drug monitoring and disease diagnosis

In recent years,scientific researchers have increasingly become interested in noninvasive sampling methods for therapeutic drug monitoring and disease diagnosis.As a result,dried saliva spot(DSS),which is a sampling technique for collecting dried saliva samples,has been widely used as an alternative matrix to serum for the detection of target molecules.Coupling the DSS method with a highly sensitive detection instrument improves the efficiency of the preparation and analysis of biological samples.Furthermore,dried blood spots,dried plasma spots,and dried matrix spots,which are similar to those of the DSS method,are discussed.Compared with alternative biological fluids used in dried spot methods,including serum,tears,urine,and plasma,saliva has the advantage of convenience in terms of sample collection from children or persons with disabilities.This review aims to provide integral strategies and guidelines for dried spot methods to analyze biological samples by illustrating several dried spot methods.Herein,we summarize recent advancements in DSS methods from June 2014 to March 2021 and discuss the advantages and disadvantages of the key aspects of this method,including sample preparation and method validation.Finally,we outline the challenges and prospects of such methods in practical applications.

Exploration of an Efficient Simultaneous Molecular Detection Method of HIV,HCV,and Syphilis from a Single Dried Blood Spot

Objective The aim of the present study was to evaluate the performance of the simultaneous detection of HIV-1 RNA,HIV-1 DNA,and HCV RNA using one dried blood spot(DBS)as an alternative sample to plasma.Method A total of 571 paired DBS/plasma samples were collected from men who have sex with men(MSM)and injection drug users(IDUs),and serological and molecular assays were performed.Using plasma results as the reference standard,the performance of DBS tests for HIV-1 RNA,HIV-1 DNA,and HCV RNA was evaluated.Pearson’s correlation coefficients and Bland-Altman analysis were performed to assess the correlation and concordance between DBS and plasma.Results Among paired plasma/DBS samples with detectable HIV-1 RNA and HCV RNA,five samples(5/32)were not detectable in DBS,while measurable HIV-1 RNA levels were present in plasma(1.44 to3.99 log10 copies/m L).There were two samples(2/94)with undetectable HCV RNA in DBS,while measurable HCV RNA levels were present in plasma(-5 to 5.99 log10 copies/m L).The correlation between HIV-1 RNA light chain variable region(VL)values obtained from plasma and DBS showed that r=0.683(P<0.01),n=27 and r=0.612(P<0.01),n=89 in HCV RNA.Bland-Altman analysis revealed that in HIV-1 RNA,the mean(±SD)difference between HIV-1 RNA in plasma and DBS was 1.00±1.01 log10 copies/m L,and all samples were within±1.96 SD(-0.97 to 2.97 log10 copies/m L)for DBS.The mean difference(±SD)in HCV RNA was 0.15±1.08 log10 copies/m L,and 94.38%(84/89)were within±1.96 SD(-1.96 to 2.67 log10 copies/m L).Overall,HIV-1 RNA and HCV RNA levels obtained from a DBS were lower than those obtained from plasma.HIV-1 DNA in a DBS showed concordant results with HIV-1 RNA in plasma.HIV-1 DNA RT-PCR using a DBS showed acceptable performance.Conclusion The performance of the simultaneous detection of HIV-1 RNA,HIV-1 DNA,and HCV RNA using one DBS was acceptable.DBS,as an alternative sample to plasma,may be a viable option for the simultaneous detection of HIV-1 RNA,HIV-1 DNA,and HCV RNA in resource-limited settings or for individuals living in areas that are difficult to access.

Dried blood spot sampling as an alternative for the improvement of hepatitis B and C diagnosis in key populations

BACKGROUND To achieve the elimination of hepatitis B and C,there is an urgent need to develop alternative strategies to increase the access of diagnosis,particularly among key populations such as people living with human immunodeficiency virus(HIV),individuals with coagulopathies and chronic kidney disease(CKD)patients.AIM To evaluate the use of dried blood spot(DBS)in the detection of hepatitis B virus(HBV)and hepatitis C virus(HCV)markers.METHODS A total of 430 individuals comprised of people living with HIV,coagulopathies and CKD provided paired serum and DBS samples.HBsAg,anti-HBc and anti-HCV were tested in those samples using a commercial electrochemiluminescence.Demographic and selected behavioral variables were evaluated to assess possible association with HBV and HCV positivity.RESULTS Using DBS,HBsAg prevalence varied from 3.9%to 22.1%,anti-HBc rates varied from 25.5%to 45.6%and anti-HCV positivity ranged from 15.9%to 41.2%in key populations.Specificities of HBV and HCV tests using DBS varied from 88.9%to 100%.The HBsAg assay demonstrated the best performance in CKD and coagulopathy individuals and the anti-HCV test had a sensitivity and specificity of 100%in people living with HIV.Accuracy of HBV and HCV detection in DBS varied from 90.2%to 100%.In the CKD group,HBsAg positivity was associated with infrequent use of condoms,and anti-HBc positivity was associated with sharing nail cutters/razors/toothbrushes.Anti-HCV reactivity was positively associated with a history of transplantation and length of time using hemodialysis in both specimens.In people living with HIV,only the male gender was associated with anti-HBc positivity in serum and DBS.CONCLUSION DBS with electrochemiluminescence are useful tools for the diagnosis and prevalence studies of hepatitis B and C among key populations and may increase the opportunity to foster prevention and treatment.

Wet and Dry Tribological Behaviors of Circular Islandic Protrusion Patterns on M2 Steel Discs under Spinning Condition

Under spinning conditions, lubricant on islandic spot patterned M2 steel disc experiences centrifugal and tangential force components. Depending upon the relative position of the spots and the flow of lubricant, accumulation of lubricant in front of patterned islandic spots creates thrusting to mating part and subsequently reduces contact between the mating couple. Whilst wear debris is likely to be spun off the plateau of the spots to their neighbouring valleys so as to reduce wear. Hence, it gives favorable tribological characteristics. Aiming at verifying such mechanisms, studies were performed on M2 steel disc specimens slid with ASSAB 17 tool steel pin. The M2 steel disc specimens were respectively （i） machined with non-patterned （NP）, （ii） etched to produce in-lined （INE） islandic patterns, and （iii） etched to produce staggered （STE） islandic spot patterns. Results indicated that the INE patterned discs gave most favorable wear characteristics, the NP of the worse characteristics whilst the STE ranged in the middle. However, the actual contact mechanism leads to the descending sequence of favorable friction behaviors nominally as： NP, INE and STE.

Accuracy and precision of dried urine spot method for the detection of Schistosoma mansoni circulating cathodic antigens in resource-limited settings

Background The World Health Organization recommends the use of Schisto point-of-care circulating cathodic anti-gens(Schisto POC-CCA)for screening of Schistosoma mansoni as it offers better sensitivity than microscopy.However,there are limitation facing the use of this method including timely availability of the test cassettes.The aim of this study was to determine the reliability of dried urine spot(DUS)method for collection of urine and detection of S.mansoni using Schisto POC-CCA cassettes in a resource-limited settings.Methods A cross-sectional study was conducted between October and November 2022 among 250 primary school children in Sengerema District,northwestern Tanzania.S.mansoni CCA was detected in filter paper-based DUSs,liquid urine using DUS Schisto POC-CCA(index),and direct urine Schisto POC-CCA(comparator)methods respectively.S.mansoni eggs in stool were detected using duplicate Kato-Katz(KK)method.The measures of accuracy were com-puted and compared between the index and comparator methods.The strength of agreement between inter-raters precisions was tested using Cohen's kappa(k).Results This study revealed S.mansoni prevalence rates of 28.8%,54.0%and 50.8%by duplicate KK,direct urine Schisto POC-CCA and DUS Schisto POC-CCA methods respectively.The mean intensity of infection among infected participants Was 86.3 eggs per gram of stool(EPG)ranging from 12.0 EPG to 824.0 EPG.The sensitivity of DUS Schisto POC-CCA and direct urine Schisto POC-CCA Was 94.44%(95%CI:89.15-99.74%)and 97.22%(95%CI:93.43-100.00%)respectively.The DUS Schisto POC-CCA method had slightly higher specificity(66.85%)than direct urine Schisto POC-CCA method(63.48%).The accuracy of the DUS Schisto POC-CCA Was found to be slightly high(74.80%,95%CI:68.94-79.06%)compared to that of direct urine Schisto POC-CCA(73.20%,95%CI:67.25-78.59%).There was good agreement between two laboratory technologists who performed the DUS Schisto POC-CCA method on similar samples(k=0.80,95%CI:0.59-0.95).Conclusions The DUS Schisto POC-CCA method had comparable S.mansoni detection accuracy to direct urine Schisto POC-CCA.This suggests that the method could be a potential alternative to direct urine Schisto POC-CCA for screening S.mansoni in resource-limited situations.

滤纸片干血斑在HIV-1 BED-CEIA新发感染检测方法中的应用

目的探讨在HIV-1 BED-CEIA新发感染检测中应用滤纸片干血斑的价值。方法研究纳入22个艾滋病自愿咨询检测(VCT)中心10226名咨询者血浆及干血斑样本作为目标实施HIV抗体检测,对通过免疫印迹法(WB)明确诊断为350例HIV感染患者的血浆样本及干血斑样本需同时实施BED-CEIA检测,观察滤纸片干血斑在HIV-1 BED-CEIA新发感染检测方法中稳定性、重复性,对两种样本检测结果存在的差异性进行对比。结果在HIV-1 BED-CEIA新发感染检测中应用滤纸片干血斑稳定性、重复性较高,重复性R^(2)值可高达0.9551。350例HIV感染患者样本检测结果中,其中295例患者样本被同时评估为长期感染,53例患者样本被同时评估为新近感染,两种样本对HIV BED-CEIA新发感染评估判定结果呈一致性(R^(2)值=0.95),一致性为99.42%。血浆样本及干血斑样本得到不同结果,样本An值均处于临界值附近(P<0.05)。结论在HIV-1 BED-CEIA新发感染检测中应用滤纸片干血斑的价值较高,检测结果稳定性、重复性较好,虽然部分样本检测结果存在一定的差异,但与血浆样本检测结果两者之间存在较佳的等效性,可广泛应用于临床HIV-1 BED-CEIA新近感染检测中。

RTM主要缺陷的研究进展

针对树脂传递模塑(RTM)成型过程中气泡、干斑两种主要缺陷,综述了RTM成型过程中气泡和干斑的形成过程、产生原因和解决方法。并介绍了国内外针对这两种缺陷的研究现状。

复合材料树脂传递模塑注胶工艺调控方法与技术

针对树脂传递模塑成型(RTM)注胶过程中,预型体内部存在局部空气无法完全排除或树脂不能完全浸润有效区域而产生气泡或干斑问题,系统分析了RTM成型过程中气泡缠裹和干斑的形成机制。介绍了注胶工艺过程中预型体渗透率区域分布差异性、预型体纱束空间交织规律差异性、预型体与模腔尺寸差异性和RTM模具进出料口位置数量与所需差异性等非确定性因素对RTM注胶流动质量的影响,并提出RTM树脂流动形态调控的新技术与方法。同时,对T型复合材料结构制件进行RTM树脂流动工艺仿真模拟,为复杂结构复合材料RTM注胶新技术的发展提供理论与方法参考。

串联质谱法和荧光分析法检测滤纸干血片苯丙氨酸的比较

目的比较荧光分析法和串联质谱法检测滤纸干血片上苯丙氨酸(Phe)水平的分布和差异,为实验室开展新生儿高苯丙氨酸血症(HPA)的筛查提供方法学依据。方法选择进行遗传代谢病筛查的滤纸干血片样本62 510例。采用荧光分析法和串联质谱法同步检测新生儿滤纸干血片的Phe浓度,同时还用串联质谱法检测酪氨酸(Tyr)浓度。采用配对Wilcoxon检验和等级相关分析评价2种方法间的差异和相关性,采用Bland-Altman一致性分析评价2种方法间的一致性。结果荧光分析法和串联质谱法均在62 510例新生儿滤纸干血片样本中检出3例HPA,敏感性均为100%。荧光分析法的阳性预期值为33.3%,串联质谱法的阳性预期值为18.8%,若联合Phe/Tyr比值,串联质谱法的阳性预期值可达100%。正常新生儿Phe浓度呈偏态分布,荧光分析法和串联质谱法检测结果<60μmol/L者分别占96.31%和95.08%,≥120μmol/L者仅占0.01%和0.03%。荧光分析法的测定值先低于串联质谱法,至97%位点(Phe≈63μmol/L)处基本持平,然后逐渐高于串联质谱法,2种方法的测定值呈正相关(r=0.43,P<0.01)。以不同浓度的Phe测定值作Bland-Altman分析,Phe浓度越高,2种方法的偏移越小,Phe>120μmol/L的19个样本点全部落在95%的一致性限内,2种方法有很好的一致性,检测结果有可替代性。结论荧光分析法和串联质谱法检测Phe在低浓度时有差异,高浓度时一致性好。2种方法对于HPA的临床判断无影响,均能用于新生儿筛查。串联质谱法可同时检测Phe和Tyr浓度,若联合Phe/Tyr比值,检出HPA的阳性预期值很高。

串联质谱检测干血滤纸片中氨基酸质控分析

目的通过对近3年的质控结果进行分析,探讨影响检测结果的因素及应对措施。方法美国疾病控制和预防中心(CDC)每年提供4批氨基酸质控干血滤纸片,利用串联质谱技术检测干血滤纸片中氨基酸水平。以美国CDC检测结果为标准,分析本实验室氨基酸质控结果偏差及其他实验室质控结果(213个实验室的均值)偏差之间的差异。结果本实验室每次质控结果所有氨基酸均在美国CDC检测结果95%可信区间内,且每一批结果的临床评价与美国CDC质控临床评价完全一致。本实验室质控结果偏差与其他实验室质控结果偏差比较,苯丙氨酸、亮氨酸、甲硫氨酸、酪氨酸和缬氨酸均无显著性差异,瓜氨酸有显著性差异(Z=-2.945P<0.005)。结论本实验室氨基酸质控结果,达到美国CDC的质控要求,瓜氨酸检测值偏低,其阳性判断切割值设定也相应降低。

RTM成型工艺中纤维体积密度不均匀性对树脂流动的影响

主要研究局部区域纤维体积密度改变对树脂流动前沿的影响。利用RTM-Worx模拟仿真软件,分析局部渗透率对流动前沿的变化及对填充该区域所用时间的影响规律。在模拟仿真的基础上,通过添加不同厚度垫片改变局部区域纤维体积密度,以对模拟仿真结果进行实验验证。仿真与实验结果表明:当局部纤维体积密度增大到一定值之后,该局部区域流动前沿出现包络现象,并且树脂填充该局部区域所用时间也开始急剧增加;当纤维体积密度继续增大时,该区域会出现树脂填充不完整的现象,最终导致制件出现干斑缺陷。

干式变压器绕组热点温度的一种计算方法

运用软件Fluent对一台干式变压器建立了可计算模型,并计算了绕组热点温度。

串联质谱分析干血滤纸片中酰基肉碱质控

目的:串联质谱技术是近几年应用于临床检验的新技术,具有特异性强、灵敏度高,一次试验可检测数十种物质的优点。本文通过对近4年的质控结果进行分析,探讨影响检测结果的因素及应对措施。方法:美国CDC每年提供4批酰基肉碱质控干血滤纸片,酰基肉碱检测方法为取直径为3mm的质控干血滤纸片放入96孔聚丙烯板,经含酰基肉碱内标的甲醇萃取,盐酸正丁醇衍生后,进行串联质谱检测。分析本实验室质控结果与美国CDC检测结果的偏差及其他实验室质控结果(169个实验室的均值)与美国CDC检测结果的偏差之间的差异。结果:本实验室每次质控结果所有酰基肉碱均在美国CDC检测结果95%可信区间内,且每一批结果的临床评价与美国CDC质控临床评价完全一致。本实验室质控结果与美国CDC检测结果的偏差与其他实验室质控结果与美国CDC检测结果的偏差比较,无显著差异,丙酰基肉碱差异显著(Z=-2.638,P<0.005),戊二酰基肉碱差异亦显著(Z=-2.482,P<0.005)。结论:本实验室酰基肉碱质控结果,达到美国CDC的质控要求,丙酰基肉碱检测值偏高,其阳性判断切割值设定也相应增高,而戊二酰基肉碱检测值偏低,其阳性判断切割值设定也相应降低。

基于反传热模型的干式变压器绕组热点温度计算

针对干式变压器绕组热点的问题,提出了一种将直接测量与间接计算相结合的绕组三维反传热模型,得到了变压器在额定负荷及0.8,1.2,1.3,1.5倍的额定负荷下的绕组最热点温度值。基于高精度的红外测温系统获得的高压绕组温度的分布及仿真运算初始化的低压绕组的温度分布,运用共轭梯度法不断修正低压绕组温度分布,使得通过正向数值求解高低压绕组传热方程所得的高压绕温度分布与实际测量所得的高压绕组温度分布之间的误差最小即为最优解,整理数据后得到整体绕组的最热点温度。将算例求解结果与IEEE干式变压器热点温度计算模型计算的结果进行对比,对比结果表明:三维反传热模型计算的结果与IEEE干式变压器热点温度计算模型的计算结果之间的误差不超过1.2%,从而证明了该计算模型可以准确的计算出干式变压器绕组热点温度。

微量明胶颗粒凝集试验检测干血斑HIV-1抗体方法的建立与评价

目的建立微量明胶颗粒凝集试验检测滤纸片干血斑HIV-1抗体的方法,评价其敏感性和特异性。方法采集某吸毒哨点106份全血样本,制成滤纸片干血斑样本和血清样本;摸索微量明胶颗粒凝集试验中抗原明胶颗粒最佳稀释倍比;比较微量明胶颗粒凝集试验检测滤纸片干血斑和ELISA检测血清HIV-1抗体的结果。结果微量明胶颗粒凝集试验检测滤纸片干血斑HIV-1抗体的结果与ELISA检测血清HIV-1抗体的结果一致。结论微量明胶颗粒凝集试验检测滤纸片干血斑HIV-1抗体的方法,可信度较高、操作简便成本低,为大规模开展HIV-1流行病学调查提供了另一种良好的实验室方法。