电化学发光法检测对弱阳性HBsAg的影响因素分析

目的了解不同保存温度下标本放置时间对弱阳性HBs Ag检测结果的影响。方法选取门诊病房送检的用电化学发光法检测HBs Ag结果为弱阳性的患者血清标本10份,观察各标本在不同放置时间及温度下的测定值。结果弱阳性HBs Ag标本分别在室温、4℃、-20℃下放置3 d、5 d、7 d后结果略有降低,但差异无统计学意义(P0.05);弱阳性HBs Ag标本在室温和4℃保存时,部分检测结果转阴性,特别是在室温情况下,第7 d检测转阴率达30%;而标本在-20℃保存,阳性数无变化。结论标本放置时间及温度对弱阳性HBs Ag检测结果差异无统计学意义,可认为ECLIA法检测弱阳性HBs Ag结果基本保持稳定。随储藏时间延长,放置温度越低,标本检测转阴率也越低。     

溶血对电化学发光免疫法测定胰岛素和C-肽的影响

目的:探讨使用电化学发光免疫法(ECLIA)测定血清胰岛素及C-肽时标本溶血程度及溶血标本放置时间对测定结果的干扰.方法:将检测标本人为干预成5种不同溶血程度的溶血标本,置于室温20℃环境下,分为4个时间段(0 min、30 min、60 min、120 min)分别采用电化学发光免疫法测定溶血和非溶血标本的胰岛素及C-肽浓度并作分析.结果:标本溶血可使胰岛素浓度降低,胰岛素浓度测定与标本溶血程度及放置时间呈负相关;标本溶血对电化学发光免疫法测定C-肽无干扰.结论:测定胰岛素时要绝对避免溶血;在标本分析前质量控制不确定情况下C-肽释放水平曲线比胰岛素释放水平曲线在临床上更具可信性.     

血清标本保存温度和时间对ALT测定的影响

目的分析不同保存温度和时间对ALT检测值的影响程度。方法选取44份临床标本,按不同时间、温度存储,不同冻融次数处理后测定ALT,计算均值和方差,采用t检验进行分析,并与首次检测结果进行比较。结果室温环境(25℃)下保存≤2d、4℃保存≤6d、-20℃保存≤10d,ALT检测值与首次差异有统计学意义(P值均0.01)。冻融≤5次,ALT检测值与冻融前差异均无统计学意义(P值均0.05)。结论血清标本于4℃保存≤2d或-20℃保存≤10d,冻融≤5次,对ALT检测值无显著影响(P值均0.05)。建议监测工作中采集血清后及时分装、-20℃保存,并于10d内送检。     

抗凝血保存温度和时间对血液分析仪测定结果的影响

目的:探讨不同条件下保存的血标本对XS-800i血液分析仪测定结果的影响.方法:观察不同温度、不同时间保存的血标本白细胞(WBC)、红细胞(RBC)、血红蛋白(HGB)、红细胞压积(HCT),平均红细胞体积(MCV)、血小板(PLT)和平均血小板体积(MPV)的变化.结果:4℃条件下保存的血标本,WBC、RBC、HGB、HCT、MCV和PLT的测定值在24h内无明显变化; MPV 8h内无明显变化,8h后升高.22℃和32℃条件下保存的血标本,WBC、RBC、HGB、HCT、MCV和PLT的测定值在12h(22℃)和6 h(32℃)内无明显变化; MPV的测定值在6 h(22℃)和4 h(32℃)内无明显变化,6h后(22℃)和4h后(32℃)明显升高,尤以32℃显著.白细胞散点图和白细胞分类在12 h时(4℃)、8 h时(22℃)和4 h时(32℃)开始发生变化.结论:抗凝血标本保存的最佳温度为4℃,22℃(室温)保存的标本应在8 h内完成检测;如果室温大于32℃,血标本采集后应在4h内完成检测.     

标本放置时间对胰岛素测定的影响

目的探讨血清标本在4℃放置不同时间对化学发光检测血清胰岛素浓度的影响。方法用真空分离胶采血管抽取21例血标本,冷冻离心分离血清,采用全自动化学发光仪即时检测胰岛素浓度,将标本于4℃分别放置1小时、3小时和24小时后重复检测,并与即时检测结果相比较。结果标本采集后即时检测与4℃下放置1小时、3小时、24小时后检测胰岛素浓度分别为(6.88±4.38)mIU/L、(6.87±4.44)mIU/L、(7.05±4.68)mIU/L、(7.57±4.60)mIU/L,经配对t检验,血清标本在4℃放置1小时和3小时所测结果与即时测定结果无统计学差异,而放置24小时后所测结果与即时测定结果有统计学差异(P=0.009)。结论标本放置时间对胰岛素测定有影响,血清胰岛素在4℃条件下不能放置24小时以上。     

血液标本存放时间对血凝中PT、APTT检测结果影响浅析

目的?分析抗凝血液标本放置不同的时间对PT、APTT检测结果的影响.方法收集100名健康状况良好的体检者的抗凝血,离心后,采用日本CA-1500全自动血凝分析仪立即检测的结果为对照组.结果标本放置4℃24、36、48、72 h以及4 dAPTT都呈显著性延长趋势(P<0.05),在12 h,APTT无明显延长,而PT值在12、24、36、48 h检测无显著性延长,差异无统计学意义(P>0.05),而在72 h、4 d时间点检测PT都较前呈现显著性延长,差异具有统计学意义(P<0.05).以本试验室参考范围PT:11~14s, APTT:24~36 s判断,则第4天检测PT、APTT的结果有75%标本PT值变为异常,62%标本APTT值变为异常.结论血液标本检测后放置冰箱保存的时间最长不得超过72 h,对于检测结果接近参考范围上限的标本则保存时间最长不得超过48 h.     

血液标本保存时间对各生化检测指标的影响分析

目的:探究血液标本保存时间对生化指标检测结果的影响。方法:随机抽取2018年4月至2019年2月期间在我院进行生化指标检测的66例患者的血液标本,分别在标本放置时间不足3h和超过3h后进行相关生化指标检测,比较不同时间点血液标本检测结果。结果:标本放置时间超过3h后血糖指标低于不足3h标本、肝功能谷丙转氨酶指标高于不足3h标本,差异有统计学意义(P0.05);其余生化指标检测差异无统计学意义(P0.05)。结论:血液标本存放时间过长可导致生化指标检测结果出现误差,进而影响检测结果的准确性,因此血液标本采集后应尽快检测。     

不同保存条件下血清荧光定量检测HCV RNA的研究

[目的 ]了解不同的保存条件对血清标本HCVRNA检测结果的影响。 [方法 ]荧光定量逆转录聚合酶链法(FQ RT PCR)。 [结果 ]血清标本 4℃存放 5dHCVRNA检测结果和室温放置 5d、-2 0℃反复冻融 5次的HCVRNA检测结果差异均无统计学意义。 [结论 ]血清标本 4℃保存 5d ,室温保存 5d ,-2 0℃反复冻融 5次 ,不影响HCVRNA的检测结果。HCVRNA检测结果重复性不好 ,应考虑内外源RNase的降解作用及所用试剂的特异性、敏感性、重复性等因素的影响。     

不同保存条件下血清荧光定量检测HCV RNA的研究

[目的]了解不同的保存条件对血清标本HCVRNA检测结果的影响。[方法]荧光定量逆转录聚合酶链法(FQ-RT-PCR)。[结果]血清标本4℃存放5d HCV RNA检测结果和室温放置5d、-20℃反复冻融5次的HCV RNA检测结果差异均无统计学意义。[结论]血清标本4℃保存5d，室温保存5d，-20℃反复冻融5次，不影响HCV RNA的检测结果。HCV RNA检测结果重复性不好，应考虑内外源RNase的降解作用及所用试剂的特异性、敏感性、重复性等因素的影响。     

标本预处理对HCV-RNA检测结果的影响

目的 研究血标本离体后的预处理及保存方式对HCV-RNA检测结果的影响. 方法 取20份丙肝患者未分离及已分离的血浆标本,于不同时间及不同温度保存后,采用RT-PCR法,检测标本中HCV-RNA含量.结果 抽血后1h内立即分离血浆的标本,分别保存于室温、4℃及-20℃,并于1d及1周后分别检测HCV-RNA含量,结果取对数后进行比较,差异无统计学意义.抽血后不分离血浆的标本,保存于4℃,于24h后进行检测,与已分离血浆,同样保存条件的标本检测结果取对数进行比较,结果差异有统计学意义. 结论 进行HCV-RNA检测时,为保证检测结果准确,血标本离体后应立即分离血清或血浆进行保存.     

Patterns of SARS-CoV-2 Testing Preferences in a National Cohort in the United States: Latent Class Analysis of a Discrete Choice Experiment

BackgroundInadequate screening and diagnostic testing in the United States throughout the first several months of the COVID-19 pandemic led to undetected cases transmitting disease in the community and an underestimation of cases. Though testing supply has increased, maintaining testing uptake remains a public health priority in the efforts to control community transmission considering the availability of vaccinations and threats from variants.ObjectiveThis study aimed to identify patterns of preferences for SARS-CoV-2 screening and diagnostic testing prior to widespread vaccine availability and uptake.MethodsWe conducted a discrete choice experiment (DCE) among participants in the national, prospective CHASING COVID (Communities, Households, and SARS-CoV-2 Epidemiology) Cohort Study from July 30 to September 8, 2020. The DCE elicited preferences for SARS-CoV-2 test type, specimen type, testing venue, and result turnaround time. We used latent class multinomial logit to identify distinct patterns of preferences related to testing as measured by attribute-level part-worth utilities and conducted a simulation based on the utility estimates to predict testing uptake if additional testing scenarios were offered.ResultsOf the 5098 invited cohort participants, 4793 (94.0%) completed the DCE. Five distinct patterns of SARS-CoV-2 testing emerged. Noninvasive home testers (n=920, 19.2% of participants) were most influenced by specimen type and favored less invasive specimen collection methods, with saliva being most preferred; this group was the least likely to opt out of testing. Fast-track testers (n=1235, 25.8%) were most influenced by result turnaround time and favored immediate and same-day turnaround time. Among dual testers (n=889, 18.5%), test type was the most important attribute, and preference was given to both antibody and viral tests. Noninvasive dual testers (n=1578, 32.9%) were most strongly influenced by specimen type and test type, preferring saliva and cheek swab specimens and both antibody and viral tests. Among hesitant home testers (n=171, 3.6%), the venue was the most important attribute; notably, this group was the most likely to opt out of testing. In addition to variability in preferences for testing features, heterogeneity was observed in the distribution of certain demographic characteristics (age, race/ethnicity, education, and employment), history of SARS-CoV-2 testing, COVID-19 diagnosis, and concern about the pandemic. Simulation models predicted that testing uptake would increase from 81.6% (with a status quo scenario of polymerase chain reaction by nasal swab in a provider’s office and a turnaround time of several days) to 98.1% by offering additional scenarios using less invasive specimens, both viral and antibody tests from a single specimen, faster turnaround time, and at-home testing.ConclusionsWe identified substantial differences in preferences for SARS-CoV-2 testing and found that offering additional testing options would likely increase testing uptake in line with public health goals. Additional studies may be warranted to understand if preferences for testing have changed since the availability and widespread uptake of vaccines.     

凝血检验项目的影响因素分析及对策

目的探讨标本放置时间、离心时间以及溶血与否对凝血检测项目的影响,以提高临床检验的准确性。方法以我院2012年1—5月间血液检测样本100例为研究对象,在不同放置时间、离心时间下进行PT、APTT、TT、Fib等凝血项目的检验。结果标本放置时间对APTT、Fib及TT值有一定的影响,对PT值无影响;离心时间对PT、APTT值有一定的影响,对TT及Fib值无影响。结论患者进行凝血项目检验一定要在标本采集后短时间内进行,离心要控制好时问和速度。     

Rapid Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 in Detention Facility,Louisiana, USA,May–June, 2020

To assess transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a detention facility experiencing a coronavirus disease outbreak and evaluate testing strategies, we conducted a prospective cohort investigation in a facility in Louisiana, USA. We conducted SARS-CoV-2 testing for detained persons in 6 quarantined dormitories at various time points. Of 143 persons, 53 were positive at the initial test, and an additional 58 persons were positive at later time points (cumulative incidence 78%). In 1 dormitory, all 45 detained persons initially were negative; 18 days later, 40 (89%) were positive. Among persons who were SARS-CoV-2 positive, 47% (52/111) were asymptomatic at the time of specimen collection; 14 had replication-competent virus isolated. Serial SARS-CoV-2 testing might help interrupt transmission through medical isolation and quarantine. Testing in correctional and detention facilities will be most effective when initiated early in an outbreak, inclusive of all exposed persons, and paired with infection prevention and control.     

即时检验法替代常规检验法检测心脏标志物的临床探讨

目的 探讨即时检验法（point-of-care testing，POCT）在实验室替代常规检验法检测急性冠脉综合征（acute coronary syndrome，ACS）患者心脏标志物的可能性。
方法 将60例拟诊为ACS的患者随机分为POCT组和常规检验组，分别在实验室内使用POCT和常规检验法检测心脏标志物肌红蛋白（Myo）、肌钙蛋白I（cTnI）、肌酸激酶同工酶（CK-MB），记录并比较患者在急诊就诊期间、入院第3天、入院第7天获取心脏标志物检测结果报告的时间、检测值变化趋势，以及住院时间和28 d死亡率。
结果 ACS患者在急诊就诊时POCT组心脏标志物的检测结果报告获取时间为（61.10 ±27.45）min，常规检验组为（76.50 ±31.25）min，两者差异有统计学意义（P < 0.05）。入院期间第3天两组检验结果报告获取时间分别为（140.67 ±81.50）min和（220.90 ±63.14）min；第7天分别为（151.83 ±65.22）min和（198.63 ±60.39）min；以上差异在两组间比较，差异均有统计学意义（P < 0.05）。两组患者心脏标志物的变化趋势基本相符。两组患者住院时间、住院费用及28 d病死率比较，差异均无统计学意义（P>0.05）。
结论 同常规检验方法相比，采用POCT法检测ACS患者的心脏标志物，有助于为ACS的早期诊断以及后续治疗争取时间，且在住院费用方面非常接近。故可以考虑引入POCT技术替代常规检验法。
     

Low rate of false-positive results with use of a rapid HIV test.

BACKGROUND: Occupational exposure to human immunodeficiency virus (HIV) is an important threat to healthcare workers. Centers for Disease Control and Prevention guidelines recommend prompt institution of prophylaxis. This requires (1) immediate prophylaxis after exposure, pending test results that may take more than 24 hours in many hospitals; or (2) performance of a rapid test. The Single Use Diagnostic System (SUDS) HIV-1 Test is used to screen rapidly for antibodies to HIV type 1 in plasma or serum, with a reported sensitivity of more than 99.9%. We used this test from January 1999 until September 2000, when it was withdrawn from the market following reports claiming a high rate of false-positive results. METHODS: We reviewed the results of postexposure HIV testing during 21 months. RESULTS: A total of 884 SUDS tests were performed on source patients after occupational exposures (883 negative results, 1 reactive result). The results of repeat SUDS testing on the reactive specimen were also reactive, but the results of enzyme immunoassay and Western blot testing were negative. A new specimen from the same patient showed a negative result on SUDS testing. This suggested a specificity of 99.9%. In the 4 months after SUDS testing was suspended, there was 1 false-positive result on enzyme immunoassay for 1 of 132 source patients (presumed specificity, 99.2%). CONCLUSION: Use of the SUDS test facilitated rapid and accurate evaluation of source specimens, obviating unnecessary prophylaxis.     

The Effect of Test Timing on the Probability of Positive SARS-CoV-2 Swab Test Results: Mixed Model Approach

BackgroundDuring the COVID-19 pandemic, swab tests proved to be effective in containing the infection and served as a means for early diagnosis and contact tracing. However, little evidence exists regarding the correct timing for the execution of the swab test, especially for asymptomatic individuals and health care workers.ObjectiveThe objective of this study was to analyze changes in the positive findings over time in individual SARS-CoV-2 swab tests during a health surveillance program.MethodsThe study was conducted with 2071 health care workers at the University Hospital of Verona, with a known date of close contact with a patient with COVID-19, between February 29 and April 17, 2020. The health care workers underwent a health surveillance program with repeated swab tests to track their virological status. A generalized additive mixed model was used to investigate how the probability of a positive test result changes over time since the last known date of close contact, in an overall sample of individuals who tested positive for COVID-19 and in a subset of individuals with an initial negative swab test finding before being proven positive, to assess different surveillance time intervals.ResultsAmong the 2071 health care workers in this study, 191 (9.2%) tested positive for COVID-19, and 103 (54%) were asymptomatic with no differences based on sex or age. Among 49 (25.7%) cases, the initial swab test yielded negative findings after close contact with a patient with COVID-19. Sex, age, symptoms, and the time of sampling were not different between individuals with an initial negative swab test finding and those who initially tested positive after close contact. In the overall sample, the estimated probability of testing positive was 0.74 on day 1 after close contact, which increased to 0.77 between days 5 and 8. In the 3 different scenarios for scheduled repeated testing intervals (3, 5, and 7 days) in the subgroup of individuals with an initially negative swab test finding, the probability peaked on the sixth, ninth and tenth, and 13th and 14th days, respectively.ConclusionsSwab tests can initially yield false-negative outcomes. The probability of testing positive increases from day 1, peaking between days 5 and 8 after close contact with a patient with COVID-19. Early testing, especially in this final time window, is recommended together with a health surveillance program scheduled in close intervals.     

A noninvasive test of exposition to toxicants: quantitative analysis of cytochrome P4501A expression in fish scales

Elevated expression of cytochrome P4501A (CYP1A) is an established biomarker for exposition to a wide range of toxicants, particularly for dioxin and structurally similar compounds. Expression of CYP1A usually is analyzed in internal organs, which involves dissection of the specimen. To avoid unnecessary animal killing, we present here an alternative method based on the monitoring of CYP1A expression in fish scales. Using beta-naphthoflavone (BNF; 50 mg/kg body wt, intraperitoneal injection) as inducer in goldfish (Carassius auratus), we monitored levels of CYP1A mRNA both in scales and liver of treated and control specimens. Treatment with BNF resulted in a similar induction of CYP1A gene in both tissues, although scales responded faster (at 8 h after treatment) than liver (between 24 and 48 h). The scale-based test has the unique advantage of allowing sequential testing in the same specimen, which facilitates analysis of the time course of CYP1A induction and allows the study of individual variability. The method implies minimal suffering of the animals, because it only requires removal of a moderate (n = 1-3) number of scales for each time point. This nondestructive, fast, and relatively inexpensive test for toxic exposure therefore is suitable for environmental monitoring and food safety control programs in which specimen preservation is required.     

血站血液检验标本误差的原因及对策探讨

目的：分析我站血液检验标本出现误差的主要原因,同时提出切实可行的预防策略,以确保血液检验标本质量可靠。方法对我站在2010年12月-2013年12月间出现的70例血液检验标本误差予以回顾性分析,探究形成血液检验标本误差的原因,并提出相应解决对策以最大限度保证血液检验标本质量。结果造成我站70例血液检验标本出现误差的主要原因包括以下几方面：①血液样本采集原因,由于血站工作人员对于血液标本的采集过程的责任意识不强,严重忽视检验报告的重要性,主要包括抗凝管使用方法有误、血液检验标本用量标准不明确等;②献血者自身因素,献血者个体间存在差异及献血者未将采血前的相关活动及饮食情况告知采血工作人员、资料填报有误;③标本送检原因,标本储存环境不符合要求,标本在运送过程中遭受大幅度震动,造成血细胞破裂;④标本检验原因,标本处理不当和检测不及时。结论在血液检验过程中除献血者自身因素外,由于血站工作人员样本采集不当、标本送检及标本检验过程的不合理操作是导致误差的主要原因,因此要注重规范血液检验中各项操作,加强送检工作,才能提高血站血液检验的准确率。