不同保存条件对PT和APTT结果的影响

目的 :探讨不同采血方式及保存条件对凝血酶原时间 (PT)和活化部分凝血活酶时间 (APTT)结果的影响。方法 :对我院正常体检人员在不同采血方式、不同温度、不同时间下测定的PT和APTT结果进行比较分析。结果 :血浆PT在 4℃保存 2h、2 4h的结果以及在2 5℃保存 2h、8h的结果与及时测定结果均无显著性差异 (P >0 .0 5 ) ;血浆APTT在 4℃保存 2h、8h的结果以及在 2 5℃保存 2h、4h的结果与及时测定结果均无显著性差异 (P >0 .0 5 )。在 3 7℃保存 2h后PT、APTT结果均出现显著性变化 (P <0 .0 5 )。两种采血方式比较 ,PT结果有显著性差异 (P <0 .0 5 )。结论 :凝血标本在室温( 2 5℃ )条件下 ,PT和APTT必须在 4h内完成检测 ,在 4℃条件下 ,必须 8h内完成检测 ;凝血标本抽血进程必须顺利且在 1min内完成     

Variability in heparin sensitivity of APTT reagents

Activated partial thromboplastin time (APTT) is the most widely used coagulation test for monitoring heparin therapy. This study quantitates the differences in heparin sensitivity of seven commercially available APTT reagents, using plasma samples obtained from 20 subjects. The reagents studied were Actin, Actin FS, Automated APTT, Cephotest, Coagachek KAPTT, Platelin plus activator, and Activated Thrombofax. The relationship between plasma heparin and APTT was established for all reagents in each subject. For each reagent studied there was a marked intersubject variability in heparin sensitivity. There was also a marked difference in heparin sensitivity among the different reagents. The average plasma heparin activities required to double baseline APTT values ranged from 0.19 +/- 0.04 (mean +/- SD) unit/mL for the most sensitive reagents (Platelin and Actin FS) to 0.43 +/- 0.12 unit/mL for the least sensitive reagent (Actin). It is concluded that reagent variability may significantly contribute to overdosage and under dosage of heparin in the individual patient. These results stress that a standard APTT reagent be developed.     

未成年人血浆PT、INR、APTT、FIB参考区间的初步建立

目的 建立适用于SYSMEX CS-5100全自动血凝分析仪及Siemens公司凝血酶原时间(PT)、国际标准化比值(INR)、活化部分凝血酶时间(APTT)、纤维蛋白原(FIB)试剂的未成年人参考区间.方法 收集2018年4月至2018年9月就诊于同仁医院眼科未成年患者2218例,成年患者460例,使用SYSMEX ...     

Wide variability in the sensitivity of APTT reagents for monitoring of heparin dosage.

AIM: To assess the sensitivity of activated partial thromboplastin time (APTT) reagents for monitoring heparin dosage using data from the UK National External Quality Assessment Scheme (NEQAS) for blood coagulation. METHODS: Data were reviewed from four surveys using samples prepared by addition of heparin to normal plasma in vitro and from two surveys in which samples were prepared using plasma from patients receiving heparin therapy (ex vivo samples). RESULTS: For both in vitro and ex vivo samples, notable differences between APTT reagents with respect to heparin sensitivity were noted. This indicates that a uniform therapeutic range of 1.5-2.5 calculated by the APTT ratio may not be appropriate for all reagents. Reagent sensitivity in ex vivo samples was substantially different to that in in vitro samples. CONCLUSIONS: The results of this large series of laboratories clearly indicate that reagent specific therapeutic ranges may be necessary, and that samples prepared by the addition of heparin to normal plasma in vitro can be misleading and should not be used.     

Saliva assays in clinical and research biology.

This paper is an update of the current knowledges about saliva components whose assays are of biological interest and have been validated. It begins by a recall of saliva physiology: role, flow rate, main components and their mode of entry into saliva. Infectious agents and their markers are not reviewed. Peptidic molecules (catecholamines, short hormonal peptides), lipids, minerals (Na, K, Li), proteins (hormones and immunoglobulins) and steroids are examined. Assays of hormonal steroids (cortisol and sexual hormones) are described in more detail because these assays have been largely used since 1980 (many papers appeared using these methods) and are well validated. This method which allows an unstressful sampling versus venipuncture is of great interest, particularly for cortisol. Saliva assays present a lot of advantages when compared to blood assays: the sampling is very easy to do especially in a non medical environment, it does not disturb intimacy when control is needed and the risk of contamination for the laboratory technician is lower than for blood. Moreover, for molecules which are linked to blood protein carriers, the saliva concentration reflects the free blood concentration.     

两种PCR方法检测狂犬病毒的敏感性和特异性比较

目的比较Nested-PCR和SYBR GreenⅠReal-Time PCR两种方法检测狂犬病毒的敏感性、特异性和时效性。方法对10倍连续稀释的狂犬病毒（疫苗株）核酸样品,采用Nested-PCR和SYBR GreenⅠReal-Time PCR方法进行平行检测,比较两种方法的敏感性;同时以登革热2型病毒、诺如病毒、星状病毒、EV71和乙型脑炎病毒核酸对两种方法的特异性进行评价。结果 SYBR GreenⅠReal-Time PCR方法可检测出2.3×106copies/μl核酸分子,与Nested-PCR方法相比,敏感度提高10倍。两种检测方法的特异性均好,与登革热2型病毒、诺如病毒、星状病毒、EV71和乙型脑炎病毒核酸均无交叉反应。SYBR GreenⅠReal-Time PCR方法检测花费3h,检测时间比Nested-PCR方法节省2h。结论与Nested-PCR相比,SYBR GreenⅠReal-Time PCR是相对高效的检测狂犬病毒的方法。     

Evaluation of 17 CE-marked HBsAg assays with respect to clinical sensitivity, analytical sensitivity, and hepatitis B virus mutant detection

Seventeen HBsAg assays, in use in the European market (CE-marked), were assessed for their diagnostic sensitivity using 38 commercially available seroconversion panels, and for their analytical sensitivity with the HBsAg ad and ay standards of the Paul-Ehrlich-Institut (PEI). In addition, the ability to detect HBsAg mutants was investigated by means of 21 recombinant HBsAg mutant samples and 5 natural mutants. Analysis of seroconversion data revealed that there were marked differences in the sensitivity among the CE-marked HBsAg assays. Differences in the window period between the most and the least sensitive assays were up to 2 weeks. Analytical sensitivities of the investigated assays ranged from 0.009 to 0.05 PEI-U/ml for HBsAg ad standard (relating to approximately 0.018 to 0.100 IU/ml of the 2nd WHO HBsAg standard) and 0.012 to 0.11 PEI-U/ml for the ay standard. Clinical and analytical sensitivities were basically correlated. The capacity to detect mutant HBsAg forms was influenced by the assay format and the properties of the monoclonal antibodies used for coating of the solid phase or in the conjugate. While some assays detected all mutants others exhibited weaknesses especially in recognising HBsAg mutations affecting loop 2 of the HBsAg a-determinant. The results obtained with the recombinant mutants were largely confirmed by the investigation of clinical samples. The study gives a broad overview of the current state of the art of about 70% of the HBsAg assays currently available in Europe. The overall sensitivity has not been improved further since 1995 when the most sensitive assay was introduced into the market. In addition, detection of HBsAg mutants seems problematic with several assays. It is concluded that there is potential to improve clinical sensitivity and mutant recognition of HBsAg assays.     

Comparison of two APTT methods of monitoring heparin therapy. APTT ratio and heparin response of pooled normal plasma

The sensitivity of the reagents for activated partial thromboplastin time (APTT) test varies greatly. Consequently the physicians who prescribe heparin based on certain APTT ratios may order different doses of heparin and produce different levels of anticoagulation in their patients, depending on the sensitivity of APTT reagent used by the laboratory. The authors have been recommending that physicians in their hospital use a therapeutic range for heparinization based on the sensitivity of the APTT reagent and keep the APTT of patients within the range of APTT of pooled normal plasma containing 0.2-0.4 units of heparin per milliliter. Because the patient's response to heparin in vivo may be different from that of pooled normal plasma, the authors planned to compare the effect of these two methods of heparin monitoring on heparin usage and complications of heparin therapy. In a retrospective study, the authors reviewed the hospital records of patients treated with continuous intravenous heparin for the management of thromboembolic disorders during two periods: one period in which the laboratory used an APTT reagent with low in vitro sensitivity to heparin (LSH) and another period in which the authors used an APTT reagent with high sensitivity to heparin (HSH). The authors found that there were no significant differences between the incidence of bleeding or thrombotic complication in the two periods. Furthermore, they found that in both periods, the patients had received similar total doses of heparin during the first 72 hours of therapy. However, as was expected from in vitro sensitivity, the APTT of patients during the LSH period was significantly lower than those during the HSH period. More heparin would have been used during the LSH period compared to the HSH period of physicians were to use the APTT ratio method for monitoring the therapy. The authors conclude that using the therapeutic range for monitoring heparin therapy based on the heparin response of pooled normal plasma will result in a more comparable level of heparinization from year to year and from center to center than by using the APTT ratio method.     

Comparison of the sensitivity of commercial APTT reagents in the detection of mild coagulopathies

This study was undertaken to evaluate the precision and sensitivity of three different commercial APTT reagents containing the activators kaolin, micronized silica, or ellagic acid. These reagents varied greatly in their ability to detect mild coagulopathies. The ellagic acid reagent was able to detect the mildest deficiencies for the most common coagulopathies. This reagent was sensitive to 50% levels of Factor VIIIC, whereas the APTT with the kaolin reagent was not prolonged until levels of 35% or less were attained. The micronized silica reagent was the least sensitive to Factor IX deficiency, detecting levels of 12% or less. Precision was similar for all reagents when tested with normal and slightly abnormal plasmas. Since methods and instrumentation vary, each laboratory should evaluate their APTT reagent to determine its precision and sensitivity.     

Sex ratio of the mutation frequencies in haemophilia A: coagulation assays and RFLP analysis.

Coagulation and RFLP data from 41 families with an isolated haemophilia A patient were used to estimate the sex ratio of mutation frequencies (nu/mu). Based on the results of coagulation assays in all the female relatives investigated, nu/mu was estimated to be 12.1 by the maximum likelihood method (95% confidence interval 3.8 to 62.5). In order to avoid the possible influence of germline mosaicism, an additional analysis was performed in which only the results in the mothers and grandmothers of an isolated patient were included. The nu/mu ratio was then estimated to be 5.2 (95% confidence interval 1.8 to 15.1). Because an estimate of nu/mu based on all available RFLP data can easily be biased in favour of males, we set up a model in which only information on the grandparental derivation of the patient's X chromosome was used, irrespective of the generation in which the mutation actually occurred. In this way nu/mu was estimated to be minimally 4. The probability of carriership for mothers of an isolated haemophilia A patient amounts to 86% with a sex ratio of 5.2. Although this would imply that 14% of the mothers are not carriers of the disease in the classical sense, they may be mosaic for the mutation and, therefore, also at risk of transmitting the mutation more than once.     

The analytic sensitivity and mutant detection capability of six hepatitis B surface antigen assays

Hepatitis B virus surface antigen (HBsAg) mutants occur in clinical specimens. We studied the analytic sensitivity and ability to detect recombinant and native mutants of 6 HBsAg assays. The ARCHITECT, AUSZYME MONOCLONAL and AxSYM assays (Abbott Diagnostics, Abbott Park, IL), the ADVIA Centaur assay (Bayer Diagnostics, Tarrytown, NY), and the Test System 3 and VITROS ECi assays (Ortho Clinical Diagnostics, Raritan, NJ) showed comparable sensitivity with wild-type HBsAg. The ARCHITECT, AUSZYME, and AxSYM assays detected all mutants that were tested. The Test System 3 and VITROS ECi assays failed to detect mutants with amino acid substitutions at positions 143, 144, and 145, which are located in the immunodominant "a" determinant. The ADVIA Centaur failed to detect substitutions at position 145 and showed negative or very low positive results for substitutions at position 143. The inability to detect HBsAg mutants may lead to misdiagnosis of hepatitis B virus infection. Further studies on the prevalence of HBsAg mutants and the ability of commercial assays to detect them are needed.     

The sensitivity of different coagulation reagents to the presence of lupus anticoagulants

The sensitivity and responsiveness of seven activated partial thromboplastin time reagents to the presence of lupus anticoagulants (LAs) was evaluated with a panel of 50 well-characterized LA plasmas. The results document that some reagents are clearly less responsive and sensitive to LAs; however, there is considerable variability between individual LA samples in these features. In addition, with 16% of these samples, immediate mixing studies showed correction of the activated partial thromboplastin time to the normal range with a 1:1 mixture of normal and LA plasma and 8% to 10% showed either a normal platelet neutralization procedure or a normal tissue thromboplastin inhibition procedure. Together, these findings provide further evidence of the laboratory heterogeneity of these inhibitors. The effect of this variability on the diagnosis of these inhibitors is discussed.     

Quantitative estimation of preanalytical variables which may influence the determinations of prothrombin time (PT) and activated partial thromboplastin time (APTT)

Prothrombin time (PT) and activated partial thromboplastin time (APTT) tests principally measure the time for a fibrin clot developed in citrated plasma after activation. For the complexity of chemical reactions, a number of preanalytical variables potentially influence the outcome of results. In the present study, we evaluated some preanalytical variables frequently encountered in clinical settings. The volumes of citrated whole-blood specimens collected from inpatients widely varied from 0.99 ml to 2.90 ml indicating 1.6% of unacceptable rate, whereas none of the specimens from outpatients was out of acceptable range. The citrated whole-blood volume significantly affected the determinations of both PT and APTT; the results indicating the more volume the longer clotting time. Also, whole-blood specimens collected in EDTA2K revealed significantly prolonged PT and APTT values in healthy subjects and the patients with anticoagulant therapy of heparin and of warfarin. Storage conditions, time and temperature might influence the PT and APTT values. In particular, citrated whole-blood specimens stood at room temperature revealed the prolonged clotting time in APTT assay by hours. The effects of other variables evaluated such as a half-volume adjustment, needle gauge or syringe type were negligible. With these results, it was concluded that; first, an accurate venipuncture is critical, particularly venipuncture from patients in wards where many different physicians and nurses are in charge and in changing by days. Secondly, the citrated whole-blood specimens should be assayed quickly without any unnecessary storage at room temperature beyond four hours.