bluuebunny/crossref_metadata_2025_split huggingface dataset:
Benign Prostate-specific Antigen (BPSA) in Serum Is Increased in Benign Prostate Disease
Authors: Linton Harry J , Marks Leonard S , Millar Lisa S , Knott Christine L , Rittenhouse Harry G , Mikolajczyk Stephen D 
Published: February 2004

Abstract
Background: BPSA is a “benign” form of free prostate-specific antigen (PSA) that is increased in prostate transition zone tissues of men with pathologic benign prostatic hyperplasia (BPH). We developed an immunoassay to determine the concentration of BPSA in the serum of men with BPH.
Methods: The BPSA antigen was purified by HPLC, and murine monoclonal antibodies were prepared by standard methods. A fluorogenic ELISA was developed with high specificity for BPSA and no cross-reactivity with other forms of PSA.
Results: The BPSA immunoassay had a lower limit of detection of 6 ng/L and a cross-reactivity of &lt;1% with all other clipped and nonclipped forms of PSA. The BPSA antibody was specific for the internal Lys182 cleavage site that characterizes BPSA. Biopsy-negative men with a median total PSA of 4.8 μg/L had a median of 0.22 μg/L BPSA, representing 25% of the free PSA in serum. BPSA ranged from 0% to 60% of the free PSA in serum. BPSA in a cohort of cancer serum also comprised 25% of the free PSA. Control serum from women or men without increased PSA had nondetectable BPSA.
Conclusions: BPSA is a significant percentage of the free PSA in BPH serum but not in control serum. The presence of prostate cancer does not alter the relative proportions of BPSA in sera with &lt;10 μg/L PSA. BPSA has a wide distribution of concentrations in the serum and may provide clinical information for the study of men with BPH.
New Enzymatic Assay for Glycohemoglobin
Authors: Sakurabayashi Ikunosuke , Watano Tatsurou , Yonehara Satoshi , Ishimaru Kaori , Hirai Kaoru , Komori Tsuguki , Yagi Masayuki 
Published: February 2004

Abstract
Background: Previous methods to measure glycohemoglobin (GHb) have been time-consuming or imprecise; we therefore developed a new enzymatic assay for GHb.
Methods: Blood cells were first hemolyzed, and hemoglobin was digested with protease to yield fructosyl amino acid. Fructosyl amino acid oxidase acts on the fructosyl amino acid and generates hydrogen peroxide, which reacts with chromogens in the presence of peroxidase. Total hemoglobin was measured spectrometrically in the same reaction tube. The results were reported as the ratio of the concentrations of GHb and hemoglobin.
Results: The measured values were comparable to those determined with a HPLC method and with an immunoassay in blood samples from 2854 patients with diabetes. Regression analysis for the enzymatic assay (y) vs the HPLC method (x) produced the following: r = 0.979; slope, 0.994 [95% confidence interval (CI), 0.986–1.001]; y-intercept, 0.04% (95% CI, −0.09% to 0.01%); n = 2854. For the enzymatic assay (y) vs the immunoassay (x), the regression statistics were as follows: r = 0.982; slope, 1.002 (95% CI, 0.995–1.009); y-intercept, 0% (95% CI, −0.05% to 0.05%); n = 2854.
Conclusions: The values measured by the new enzymatic assay are sufficiently correlated with those of the conventional HPLC method and immunoassay, but the proposed assay for GHb is rapid and has high precision.
Detection of Anti-Human T-Lymphotropic Virus Type I Antibody in Whole Blood by a Novel Counting Immunoassay
Authors: Yamaguchi Kazunari , Yonemura Yuji , Okabe Hiroaki , Takahama Yoichi , Nagai Shinya , Yamaguchi Haruki , Hirai Kojiro 
Published: February 2004

Abstract
Background: Assays to screen for and confirm the presence of the antibody for human T-lymphotropic virus type I (HTLV-I) are currently performed with serum or plasma. We developed and evaluated a new counting immunoassay (CIA) for the detection of HTLV-I antibody in whole blood, using recombinant and synthetic peptide antigens.
Methods: We assessed the CIA for detection of HTLV-I antibody in whole blood and plasma. The CIA is an immunity-measuring method that combines latex agglutination with particle-counting technology. The numbers of agglutinated latex particles, single latex particles, and blood cells in a sample are measured based on differences in particle size between latex particles and blood cells.
Results: The CIA and ELISA methods were in agreement for all 24 plasma samples tested, including those from 6 patients with HTLV-I-associated diseases, 6 HTLV-I carriers, and 12 HTLV-I antibody-negative individuals. The concordance between the ELISA (plasma) and the CIA (whole blood) for samples from 24 patients was 100%. The concordance between a particle agglutination method (plasma) and the CIA (plasma or whole blood) for 1065 patients was 99.5%. The concordance between results obtained for 1065 pairs of plasma and whole blood samples with the CIA method was 100%. HTLV-I antibody in whole blood was stable for 3 days after blood collection. With this CIA method, results were available within 15 min.
Conclusions: The CIA method can be used in screening for HTLV-I. The use of whole blood rather than serum or plasma reduces the sample volume and number of blood collections required, as well as assay time.
Influence of Urinary Stones on the Composition of a 24-Hour Urine Sample
Authors: Laube Norbert , Pullmann Michael , Hergarten Stefan , Hesse Albrecht 
Published: February 2004

Abstract
Background: It can be assumed that stones in the urinary tract continuously increase in size by incorporating material from urine. Consequently, urine will exhibit depleted concentrations of lithogenic constituents when urinary stones are present in the patient’s urinary tract.
Methods: To calculate the influence of the depletion effect, we considered two different models of stone growth. In the first model, the increase in stone size depends only on the urinary concentration of a lithogenic substance; the second model also considers the surface area of the growing stone. The case of only one kidney being affected by stone formation is considered separately. We discuss example calculations involving the formation of calcium oxalate.
Results: The calculated depletion effects are of a nonnegligible order of magnitude. Assuming both a measured oxalate concentration of, e.g., 0.37 mmol/L and a reasonable in vivo stone growing rate of 10 mm3/day, a relative underestimation of the real “in situ” oxalate concentration between ∼21% (model 1) and ∼42% (model 2) occurs. The depletion effect increases markedly with increasing stone growth rate.
Conclusions: Metabolic status can be evaluated correctly only in patients who have been declared “stone-free”, e.g., after stone removal. Because the expected stone-related depletion effect in most cases is of high clinical relevance, we recommend estimating the effect of the order of magnitude of the depletion on actual urinary composition.
Comparison of Eight Computer Programs for Receiver-Operating Characteristic Analysis
Authors: Stephan Carsten , Wesseling Sebastian , Schink Tania , Jung Klaus 
Published: February 2004

Abstract
Background: ROC analysis is widely accepted to assess and compare diagnostic validity of laboratory tests. Within the last few years, many new ROC programs have become available but have not been systematically evaluated. The aim of this study was to assess different ROC programs regarding their ease of use, mathematical correctness, final output, and their compatibility with other graphics programs.
Methods: Eight available programs running under Windows (AccuROC, Analyse-It, CMDT, GraphROC, MedCalc, mROC, ROCKIT, and SPSS) were evaluated. ROC analyses of prostate-specific antigen and related values were performed from a dataset of 928 men with prostate cancer and benign prostatic hyperplasia and corresponding subsets. Criteria such as data input, data output, and correctness and completeness of results were used to evaluate the practicability of the programs.
Results: Although the programs produced equivalent results (areas under the curves and their characteristics), we observed deficiencies concerning input of data, processing of the output data, and completeness of the results. Analyse-It, AccuROC, and MedCalc exhibited good performance, but each program had different shortcomings. Only GraphROC could compare curves at a certain sensitivity or specificity cutoff.
Conclusions: Adequate ROC analysis and ROC plotting cannot be performed with a single program. Analyse-It, AccuROC, and MedCalc can be recommended with certain limitations. Further improvements of the programs are necessary.
RIA for Serum Holo-Transcobalamin: Method Evaluation in the Clinical Laboratory and Reference Interval
Authors: Loikas Saila , Löppönen Minna , Suominen Pauli , Møller Jan , Irjala Kerttu , Isoaho Raimo , Kivelä Sirkka-Liisa , Koskinen Pertti , Pelliniemi Tarja-Terttu 
Published: February 2004

Abstract
Background: Decreased serum holo-transcobalamin (holoTC) could be the earliest marker of cobalamin (Cbl) deficiency, but there has been no method suitable for routine use. We evaluated a new commercial holoTC RIA, determined reference values, and assessed holoTC concentrations in relation to other biochemical markers of Cbl deficiency.
Methods: The reference population consisted of 303 individuals 22–88 years of age, without disease or medication affecting Cbl or homocysteine metabolism. In elderly individuals (≥65 years), normal Cbl status was further confirmed by total homocysteine (tHcy; &lt;19 μmol/L) and methylmalonic acid (MMA; &lt;0.28 μmol/L) concentrations within established reference intervals. HoloTC in Cbl deficiency was studied in a population of 107 elderly individuals with normal renal function. The Cbl deficiency was graded as potential (total Cbl ≤150 pmol/L or tHcy ≥19 μmol/L), possible (total Cbl ≤150 pmol/L and either tHcy ≥19 μmol/L or MMA ≥0.45 μmol/L), and probable (tHcy ≥19 μmol/L and MMA ≥0.45 μmol/L).
Results: The intra- and between-assay imprecision (CV) for the holoTC RIA were 4–7% and 6–8%, respectively. A 95% central reference interval for serum holoTC was 37–171 pmol/L. All participants (n = 16) with probable Cbl deficiency, 86% of those with possible, and 30% of those with potential Cbl deficiency had holoTC below the reference limit (&lt;37 pmol/L). The holoTC correlated with total Cbl (rs = 0.80; P &lt;0.0001) and inversely with MMA (rs = −0.52; P &lt;0.0001). HoloTC concentrations were significantly (P = 0.01) higher in women than in men.
Conclusions: The new holoTC RIA is precise and simple to perform. Low holoTC is found in individuals with biochemical signs of Cbl deficiency, but the sensitivity and specificity of low holoTC in diagnosis of Cbl deficiency need to be further evaluated.
Standardization of Immunoassays for Measurement of High-Sensitivity C-reactive Protein. Phase I: Evaluation of Secondary Reference Materials
Authors: Kimberly Mary M , Vesper Hubert W , Caudill Samuel P , Cooper Gerald R , Rifai Nader , Dati Francesco , Myers Gary L 
Published: February 2004

Abstract
Background: Inflammation contributes to the development and progression of atherosclerosis, and C-reactive protein (CRP) can be used as a marker to assess risk for cardiovascular diseases. As variability among existing high-sensitivity CRP (hsCRP) assays can lead to misclassification of patients and hamper implementation of population-based medical decision points, standardization of hsCRP assays is needed.
Methods: We evaluated five proposed secondary reference materials, including two diluted preparations of Certified Reference Material 470 (CRM470), two preparations of a serum-based material with recombinant CRP added, and one serum-based material with isolated CRP added. Twenty-one manufacturers participated in the comparison with 28 different assays. We examined imprecision, linearity, and parallelism with these materials and with fresh serum.
Results: All materials had similar imprecision; CVs for the undiluted materials were 2.1–3.7%. None of the materials was linear across all assays. Each had between one and three cases of nonlinearity, with one preparation of CRM470 having the fewest cases of nonlinearity. Although none of the materials was parallel across all assays, the differences in slope from fresh serum were similar across all assays.
Conclusions: All materials performed similarly with regard to imprecision, linearity, and parallelism. As one preparation of CRM470 had slightly better characteristics than the other materials and because CRM470 had been certified previously as a reference material for the acute-phase reactant range, it will be used in the next phase to standardize hsCRP assays.
Evaluation of Electronic Microarrays for Genotyping Factor V, Factor II, and MTHFR
Authors: Erali Maria , Schmidt Ben , Lyon Elaine , Wittwer Carl 
Published: February 2004

Abstract
Background: Genetic risk factors associated with venous thrombosis include mutations in the factor V (Leiden), factor II (prothrombin), and methylenetetrahydrofolate reductase (MTHFR) genes. We evaluated a method using electronically addressable microarrays for the detection of mutations in these genes that have been associated with vascular disease.
Methods: The NanoChip® Molecular Biology Workstation (Nanogen) uses electronic microarrays for mutation detection. Factor V, factor II, and MTHFR genotypes identified in the NanoChip system on 225 samples were compared with genotypes from LightCycler® assays (Roche). We determined within- and between-cartridge signal and ratio variation and analyzed the effect of additional mutations at or near the detection area used for the NanoChip assays.
Results: Genotypes determined for all three mutations on the NanoChip platform were in complete concordance with LightCycler results. Within-cartridge signal variation as measured by the CV of fluorescence signals was &lt;10% for each allele when present. The within-cartridge CV for heterozygous mutant/wild-type ratios was &lt;8.5%, and between-cartridge CV was &lt;18%. A dilution study showed that results could be obtained in this assay with 6 ng of nucleic acid per PCR, the lowest input tested. The presence of additional sequence variations near the expected mutations can produce equivocal or discrepant results.
Conclusions: Mutation detection using the NanoChip Molecular Biology Workstation was accurate and reproducible for the three assays evaluated.
Quantitative Analysis of Pleural Fluid Cell-free DNA as a Tool for the Classification of Pleural Effusions
Authors: Chan Michael H M , Chow Kai Ming , Chan Anthony T C , Leung Chi Bon , Chan Lisa Y S , Chow Katherine C K , Lam Ching Wan , Lo Y M Dennis 
Published: February 2004

Abstract
Background: Recently, much interest has been focused on the quantification of DNA in miscellaneous body fluids. In this study, the application is extended to classifying pleural effusions by measuring cell-free DNA in pleural fluid.
Methods: We recruited 50 consecutive patients with pleural effusions with informed consent. Pleural fluids were centrifuged at 13 000g, with supernatants aliquoted for extraction and analysis of β-globin DNA sequence by quantitative real-time PCR. Serum and pleural fluid biochemistries were performed to classify pleural effusions using the modified criteria of Light et al. (Ann Intern Med 1972;77:507–13). The ROC curve was plotted to determine the cutoff DNA concentration for classifying pleural fluids as transudates or exudates. Indicators of diagnostic accuracy were calculated for both pleural fluid DNA and modified criteria of Light et al., using the discharge, microbiologic, and histologic diagnoses as the reference standard.
Results: The area under the ROC curve was 0.95 [95% confidence interval (CI), 0.84–0.99]. At 509 genome-equivalents/mL, pleural fluid DNA alone correctly classified 46 of 50 pleural effusions with 91% sensitivity (95% CI, 76–98%), 88% specificity (95% CI, 64–98%), and positive and negative likelihood ratios of 7.7 (95% CI, 3.1–19.5) and 0.10 (95% CI, 0.04–0.27), respectively. With the modified criteria of Light et al., 43 of 50 pleural effusions were correctly classified with 97% sensitivity (95% CI, 91–100%) and 67% specificity (95% CI, 45–89%). There were significant correlations between cell-free DNA and both lactate dehydrogenase and total protein in pleural fluid, suggesting their common origin.
Conclusions: Pleural fluid DNA concentrations are markedly increased in exudative effusions, making it a potential new tool to evaluate the etiologic causes of pleural effusions.
Detection of Autoantibodies to Protein Tyrosine Phosphatase-like Protein IA-2 with a Novel Time-resolved Fluorimetric Assay
Authors: Westerlund-Karlsson Annette , Suonpää Katriina , Ankelo Matti , Ilonen Jorma , Knip Mikael , Hinkkanen Ari E 
Published: February 2004

Abstract
Background: Circulating autoantibodies to pancreatic glutamic acid decarboxylase (GAD65; the 65-kDa isoform of glutamic acid decarboxylase), protein tyrosine phosphatase-like protein IA-2, and insulin can be used as predictive markers of type 1 diabetes. We developed a novel assay for the detection of IA-2 autoantibodies (IA-2As) in serum based on time-resolved fluorimetry, hypothesizing that this kind of assay could provide several advantages over methods described to date, including radiobinding assays (RBAs) and ELISAs.
Methods: The intracellular part of IA-2 (IA-2ic) was biotinylated and bound to streptavidin-coated 96-well plates by simultaneous incubation with serum samples and glutathione S-transferase (GST)-IA-2ic fusion protein. GST-IA-2ic captured by autoantibodies in the serum was detected with europium-labeled anti-GST antibody, and the signal was measured in a time-resolved fluorimeter. A serum sample panel from 100 patients with newly diagnosed type 1 diabetes and 100 unaffected controls was analyzed with the new assay and a conventional RBA.
Results: Among the 100 serum samples from patients with type 1 diabetes, the time-resolved fluorimetric assay identified 74 IA-2A-containing sera, whereas the RBA detected 80 IA-2A-positive samples. Five of the six samples positive in the RBA but not detected by the time-resolved fluorimetric assay were only weakly positive in the RBA. The performance time of the time-resolved fluorimetric assay was 2.5 h compared with 10–12 h required by the RBA.
Conclusions: The time-resolved fluorimetric assay provides a simple, nonradioactive analysis method for the detection of IA-2As with a specificity and a sensitivity comparable to the RBA method. This assay allows substantial reduction in performance time compared with the conventional RBA.
Chemiluminescence Assay Improves Specificity of Hepatitis C Antibody Detection
Authors: Dufour D Robert , Talastas Mageli , Fernandez Maria D A , Harris Barbara 
Published: February 2004

Abstract
Background: Antibodies to hepatitis C virus (anti-HCV) have typically been detected by enzyme immunoassay (EIA). A chemiluminescence assay (CA) for anti-HCV is now commercially available.
Methods: We compared the positive rate for a CA in a HCV screening program for veterans with historical rates obtained with EIA. We also compared results in 2824 samples tested by both methods and assessed the significance of low signal-to-cutoff (S/C) ratios.
Results: The frequency of CA-positive results was significantly lower than with EIA (12.6% vs 16.0%; P &lt;0.0001). The frequency of low S/C ratios was also significantly lower with CA (11.5% vs 20.0%; P &lt;0.0001). Among low-positive values, samples positive by CA were significantly less likely to be recombinant immunoblot assay (RIBA)-negative (64% vs 84%; P &lt;0.0005). In parallel testing, results for 111 samples (3.9%) were discrepant between the two assays; all but 6 had low S/C ratios, and confirmatory testing was performed on all but 8 samples. Of 56 EIA-positive, CA-negative samples tested by RIBA, only 1 was positive. Of 24 CA-positive, EIA-negative samples, 62% were RIBA-negative. Using a negative RIBA result as an indication of false-positive anti-HCV results, the positive predictive value of EIA was 93% compared with 98% with CA. HCV RNA was positive in 90% of samples high-positive by both CA and EIA. Only 2 of 30 (7%) low-positive CA samples were RNA-positive.
Conclusions: CA produces fewer false-positive and fewer low-positive results that require confirmatory RIBA testing. The S/C ratio remains useful for characterizing positive results.
Urinary Cannabinoid Detection Times after Controlled Oral Administration of Δ9-Tetrahydrocannabinol to Humans
Authors: Gustafson Richard A , Levine Barry , Stout Peter R , Klette Kevin L , George M P , Moolchan Eric T , Huestis Marilyn A 
Published: February 2004

Abstract
Background: Urinary cannabinoid excretion and immunoassay performance were evaluated by semiquantitative immunoassay and gas chromatography–mass spectrometry (GC/MS) analysis of metabolite concentrations in 4381 urine specimens collected before, during, and after controlled oral administration of tetrahydrocannabinol (THC).
Methods: Seven individuals received 0, 0.39, 0.47, 7.5, and 14.8 mg THC/day in this double-blind, placebo-controlled, randomized, clinical study conducted on a closed research ward. THC doses (hemp oils with various THC concentrations and the therapeutic drug Marinol®) were administered three times daily for 5 days. All urine voids were collected over the 10-week study and later tested by Emit II®, DRI®, and CEDIA® immunoassays and by GC/MS. Detection rates, detection times, and sensitivities, specificities, and efficiencies of the immunoassays were determined.
Results: At the federally mandated immunoassay cutoff (50 μg/L), mean detection rates were &lt;0.2% during ingestion of the two low doses typical of current hemp oil THC concentrations. The two high doses produced mean detection rates of 23–46% with intermittent positive tests up to 118 h. Maximum metabolite concentrations were 5.4–38.2 μg/L for the low doses and 19.0–436 μg/L for the high doses. Emit II, DRI, and CEDIA immunoassays had similar performance efficiencies of 92.8%, 95.2%, and 93.9%, respectively, but differed in sensitivity and specificity.
Conclusions: The use of cannabinoid-containing foodstuffs and cannabinoid-based therapeutics, and continued abuse of oral cannabis require scientific data for accurate interpretation of cannabinoid tests and for making reliable administrative drug-testing policy. At the federally mandated cannabinoid cutoffs, it is possible but unlikely for a urine specimen to test positive after ingestion of manufacturer-recommended doses of low-THC hemp oils. Urine tests have a high likelihood of being positive after Marinol therapy. The Emit II and DRI assays had adequate sensitivity and specificity, but the CEDIA assay failed to detect many true-positive specimens.