Abstract：
:A modified pentamer formation assay (PFA) for quantification of tacrolimus and active metabolites after extraction from whole blood is described. The lower limit of detection was 2 microg/L. Intraassay precision (CV) was 5.7-13.7%, and the interassay CV was 6. 1-14.9%. Tacrolimus trough concentrations in 104 whole blood specimens from liver and kidney transplant recipients were compared with results from HPLC-tandem mass spectrometry (LC/MS/MS) and microparticle enzyme immunoassay (MEIA-II). Data were analyzed by difference plots and are presented as median (95% confidence intervals) of the method differences. MEIA-II results were on average 2.00 microg/L (range, -0.08 to 5.17 microg/L) higher than LC/MS/MS, whereas PFA results were only 1.07 microg/L (range, -2.62 to 5.33 microg/L) higher. Of 104 specimens tested, 25 displayed differences >/=3 microg/L between MEIA-II and PFA: median difference, 4.65 microg/L (range, 3.01-8.79 microg/L). The corresponding median difference between PFA and LC/MS/MS was -0.91 microg/L (range, -4.11 to 0.85 microg/L), and the difference between MEIA-II and LC/MS/MS was 3.67 microg/L (range, 1.88-6.34 microg/L), suggesting the presence of inactive metabolites that caused a positive bias in the immunoassay. In contrast, similar median differences were observed for the remaining 79 specimens: MEIA-II minus LC/MS/MS, 1.78 microg/L (range, -0.45 to 4.11 microg/L); PFA minus LC/MS/MS, 1.90 microg/L (range, -1.70 to 5.50 microg/L). Active tacrolimus metabolites may have contributed to the higher apparent tacrolimus concentrations in these specimens.
journal_name
Clin Chemjournal_title
Clinical chemistryauthors
Armstrong VW,Schuetz E,Zhang Q,Groothuisen S,Scholz C,Shipkova M,Aboleneen H,Oellerich Msubject
Has Abstractpub_date
1998-12-01 00:00:00pages
2516-23issue
12eissn
0009-9147issn
1530-8561journal_volume
44pub_type
杂志文章abstract：:Plasma hydroxyproline fractions--free-plus-peptide and free--were determined by a method involving centrifugal ultrafiltration and the procedure of Kivirikko et al. [Anal. Biochem. 19, 249 (1967)]. Within- and between-day precision (CV) for the combined fractions was 4--5% and 2.8--6%, respectively. Mean analytical re...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1978-02-01 00:00:00
abstract：:We present an improved Na+-selective liquid membrane electrode for measurement of Na+ concentrations in both undiluted serum and urine. The values for urinary Na+ obtained with the ion-selective electrode agree well with those obtained with the flame photometer. The correlation gives a standard residual deviation of +...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1983-08-01 00:00:00
abstract：:The location of the Reference Value for an analyte within the population distribution affects the magnitude of error due to methodological bias. Using the gaussian distribution, we evaluated the effects of systematic and proportional biases of the method (positive and negative), mean value, and standard deviation on t...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1988-11-01 00:00:00
abstract：BACKGROUND:Identifying novel risk markers in cardiovascular patients remains a research priority. Longer follow-up generally is considered favorable in such studies, but associations of interest may become attenuated with increasing follow-up. This issue has not been adequately addressed in the context of patient cohor...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2016.263202
更新日期：2017-03-01 00:00:00
abstract：:Published estimates of the imprecision characteristics of immunoassays are often based on quantities of data that seem to be inadequate. The increasing use of imprecision profiles has not necessarily improved the situation. We describe and illustrate a method of computing 95% confidence intervals for profiles estimate...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1990-07-01 00:00:00
abstract：:We describe a liquid-chromatographic assay for AZT in human plasma and urine. This assay involves the use of two internal standards, allowing reference of AZT peaks to the appropriate internal standard, the choice depending on the range of concentrations encountered. This method is isocratic, specific, sensitive enoug...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1988-08-01 00:00:00
abstract：:This article reviews key advances in ion-selective electrode technology that have made potentiometric measurements of ionized calcium (Ca2+) reliable and precise. Our use of two second-generation Ca2+ analyzers (Radiometer ICA1 and NOVA 8) made possible uninterrupted service as volume increased to 31 640 patient tests...
journal_title：Clinical chemistry
pub_type： 杂志文章,评审
doi：
更新日期：1986-08-01 00:00:00
abstract：BACKGROUND:The Dutch project "Calibration 2000" aims at harmonization of laboratory results via calibration by development of matrix-based secondary reference materials. We considered the selection, preparation, and characterization of 34 potential reference materials (PRMs). METHODS:Sixteen PRMs were prepared either ...
journal_title：Clinical chemistry
pub_type： 杂志文章,多中心研究
doi：
更新日期：2002-09-01 00:00:00
abstract：BACKGROUND:Previous studies have shown a single linear relationship between mean plasma glucose (MPG) and hemoglobin A(1c) (HbA(1c)). We examined the relationship in different treatment groups of patients with type 1 diabetes participating in the Diabetes Control and Complications Trial (DCCT). METHODS:Seven-point glu...
journal_title：Clinical chemistry
pub_type： 杂志文章,随机对照试验
doi：10.1373/clinchem.2006.079756
更新日期：2007-05-01 00:00:00
abstract：BACKGROUND:C-reactive protein (CRP) increases in response to inflammation and is purported to be a risk factor for atherogenesis. We recently demonstrated that a scavenger receptor, lectin-like oxidized LDL receptor (LOX-1), is a receptor for CRP. In light of the overlapping ligand spectrum of scavenger receptors such ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2009.140202
更新日期：2010-03-01 00:00:00
abstract：:I present the general pattern relationship between (a) plasma fibrinogen and cholinesterase activity and (b) plasma fibrinogen and hemoglobin, in 250 and 310 hospitalized adults, respectively. Although responses of cholinesterase were often unrelated to fibrinogen, when its activity in plasma was depressed, above-norm...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1977-01-01 00:00:00
abstract：BACKGROUND:Cardiac troponins are associated with cardiovascular risk in the general population, but whether temporal changes in cardiac troponin I provide independent prognostic information remains uncertain. Using a large community-based cohort with follow-up close to the present day, we aimed to investigate the assoc...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2018.301069
更新日期：2019-07-01 00:00:00
abstract：BACKGROUND:Hyperglycosylated human chorionic gonadotropin (hCG-h) contains larger and more complex carbohydrate chains than regular human chorionic gonadotropin (hCG). hCG-h is thought to be the major form of hCG produced by testicular cancers and it has been suggested to play a key role in tumor invasion, but studies ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2012.183723
更新日期：2012-07-01 00:00:00
abstract：:17 alpha-Hydroxyprogesterone, cortisol, and 11-deoxycortisol were extracted with methylene chloride, separated by liquid chromatography, identified by their retention times, and quantitated by monitoring the absorbance at 254 nm. The method is specific and sensitive to as little as 2.5 ng of 17 alpha-hydroxyprogestero...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1981-07-01 00:00:00
abstract：BACKGROUND:Several compounds in the choline oxidation pathway are associated with insulin resistance and prevalent diabetes; however, prospective data are scarce.We explored the relationships between systemic and urinary choline-related metabolites and incident type 2 diabetes in an observational prospective study amon...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2015.250761
更新日期：2016-05-01 00:00:00
abstract：:Consecutive values for serum osmolality measured in a patient exceeded (548 mOsm) the previously reported pathological range and, indeed, exceeded that generally considered compatible with life. The patient was receiving large amounts of intravenous dimethyl sulfoxide as part of an experimental protocol to control int...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1980-11-01 00:00:00
abstract：:We have developed an HPLC method for measuring carbamylated hemoglobin (CarHb), based on the quantification of valine hydantoin formed from the released NH2-terminal carbamyl valine residue after acid hydrolysis of hemoglobin. In uremia, CarHb is produced by nonenzymatic post-translational modification of the terminal...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1990-04-01 00:00:00
abstract：BACKGROUND:Human chorionic gonadotropin (hCG) is a heterodimeric glycoprotein hormone that exists in multiple forms. Immunoassays commonly used in clinical laboratories measure intact hCG, total beta hCG (intact hCG + hCG free beta-subunit), and/or hCG free beta-subunit. Measurement of serum concentrations of hCG is us...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2007.098822
更新日期：2008-04-01 00:00:00
abstract：:We describe an automated (ABA-100) enzymic method for determination of urinary oxalate by use of oxalate oxidase (EC 1.2.3.4) isolated from beet stems. The H2O2 produced by the oxidation of oxalate by oxalate oxidase is measured by coupling with oxidation and conjugation of 3-methyl-3-benzothiazolinone hydrazone with ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1983-10-01 00:00:00
abstract：:Intra- and interindividual components of biological variation have been determined for total thyroxin (TT4), free thyroxin (FT4), total triiodothyronine (TT3), free triiodothyronine (FT3), and thyrotropin (TSH). Calculated analytical goals (CV, %) for the precision required for optimal patient care are: TT4 less than ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1986-06-01 00:00:00
abstract：:We evaluated and compared five commercial radioimmunoassay kits with a standard counter-immunoelectrophoretic assay for the measurement of prostatic acid phosphatase in serum. Four of the five radioimmunoassays performed as described by the supplier with respect to sensitivity, stability, precision, linearity, analyti...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1981-10-01 00:00:00
abstract：:We determined approximately 15,000 laboratory values in 236 individuals between the ages of 60 and 90 y, 22 individuals between 90 and 99 y, and 69 individuals greater than or equal to 100 y, and compared these with values in young adults. We tested 47 different analytes in the 60-90-y group and 93 analytes in the gre...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1992-06-01 00:00:00
abstract：BACKGROUND:C-reactive protein (CRP) is a widely recognized indicator of inflammation and is known to play an important role in atherogenesis. Recent prospective studies have demonstrated that increased CRP concentrations within the reference interval are a strong predictor of myocardial infarction, stroke, sudden cardi...
journal_title：Clinical chemistry
pub_type： 杂志文章,评审
doi：10.1373/49.8.1258
更新日期：2003-08-01 00:00:00
abstract：:We developed a new colorimetric method, DNA enzyme immunoassay (DEIA), for detecting specific hybrids of complementary nucleic acids and applied it to the detection of hepatitis B virus (HBV) DNA amplified from serum samples by means of the polymerase chain reaction (PCR) technique. The method is based on the ability ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1991-03-01 00:00:00
abstract：BACKGROUND:The ratio of plasma aldosterone concentration to plasma renin activity (PRA) is considered the screening test of choice for primary aldosteronism. Uncertainty exists, however, regarding its diagnostic accuracy and the effects of antihypertensive drugs and dietary sodium balance on test characteristics. METH...
journal_title：Clinical chemistry
pub_type： 临床试验,杂志文章
doi：10.1373/clinchem.2004.041780
更新日期：2005-02-01 00:00:00
abstract：BACKGROUND:Yersinia pestis, the causative agent of the zoonotic infection plague, is a major concern as a potential bioweapon. Current real-time PCR assays used for Y. pestis detection are based on plasmid targets, some of which may generate false-positive results. METHODS:Using the yp48 gene of Y. pestis, we designed...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2005.051839
更新日期：2005-10-01 00:00:00
abstract：:We describe a chromatographic procedure for sensitive (2.0 mumol/L), specific quantification of vanillylmandelic acid (VMA) in urine with iso-VMA as an internal standard. After rapid extraction from urine, the VMA is determined by isocratic reversed-phase ion-pair chromatography on a bonded C8 column and detection of ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1986-04-01 00:00:00
abstract：BACKGROUND:It has been postulated that changes in S-adenosylhomocysteine (AdoHcy), a potent inhibitor of transmethylation, provide a mechanism by which increased homocysteine causes its detrimental effects. We aimed to develop a rapid and sensitive method to measure AdoHcy and its precursor S-adenosylmethionine (AdoMet...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：10.1373/clinchem.2004.046995
更新日期：2005-08-01 00:00:00
abstract：:We describe a new double-antibody enzyme radioimmunoassay for thyroxin-binding globulin (TBG) in serum. A TBG-beta-D-galactosidase complex was prepared with m-maleimidobenzoyl N-hydroxysuccinimide ester. The mean analytical recovery of TBG added to serum was 99%, sample volume and TBG value were linearly related, and ...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1982-12-01 00:00:00
abstract：:We report the presence of complexes between aspartate aminotransferase (AST, EC 2.6.1.1) and immunoglobulin (Ig) in the serum of a patient suffering from lung cancer with metastasis to the liver. After fractionation of the serum by gel filtration, AST-Ig complexes (AST-IgA, AST-IgG) were demonstrated by counterimmunoe...
journal_title：Clinical chemistry
pub_type： 杂志文章
doi：
更新日期：1983-02-01 00:00:00
