bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous Assay of Corticosterone and Cortisol in Plasma by Reversed-Phase Liquid Chromatography
Authors: Hariharan M , Naga S , VanNoord T , Kindt E K 
Published: January 2020

Abstract
We have developed a simple, specific, and sensitive reversed-phase liquid-chromatographic method for accurate and simultaneous analysis of corticosterone and cortisol in human plasma. We achieved a detection limit of 300 ng/L for both steroids by modifying the old solid-phase extraction method to make use of "Tef Elutor" C18 columns, using a minibore (100 x 2 mm) analytical column, and using an ultraviolet detector with a 10-mm-pathlength flow cell. With the new extraction method absolute extraction efficiencies were greater than 90% for all the analytes, including the internal standard, flumethasone. The mobile phase was water (containing 5 mL of triethylamine per liter and citric acid to adjust the pH to 6.5), tetrahydrofuran, and acetonitrile (82/10/8 by vol). The average interassay CV for corticosterone at 0-25 micrograms/L was 6.5%; that for cortisol at 0-300 micrograms/L was 3.8%. The analytical recovery relative to the internal standard was 100.2% for cortisol and 102.6% for corticosterone. Possible interferences from drugs and other steroids were studied.
Free α-Subunit, Free β-Subunit of Human Chorionic Gonadotropin (hCG), and Intact hCG in Sera of Healthy Individuals and Testicular Cancer Patients
Authors: Madersbacher S , Klieber R , Mann K , Marth C , Tabarelli M , Wick G , Berger P 
Published: January 2020

Abstract
To determine the serum concentrations of human chorionic gonadotropin (hCG), its free beta-subunit (hCG beta), and the free alpha-subunit (free alpha) common to all human glycoprotein hormones under physiological and pathological conditions, we developed monoclonal antibody-based immunoenzymometric assays. Free alpha-subunit was detected in the sera of all healthy individuals of both sexes; hCG was measurable in sera of 54% of the men, and 46% were positive for free hCG beta; in nonpregnant women, 69.5% were positive for hCG, 68.4% for the free beta-subunit. Pathological conditions, i.e., hCG-producing tumors, were studied in vitro and in vivo. In vitro, the concentrations of hCG, free hCG beta, and free alpha in tissue-culture supernates of a choriocarcinoma cell-line ("JAR") showed a parallel pattern during time-course analysis. In vivo, in long-term follow-up studies of 13 patients with testicular cancer, serum concentrations of the three analytes paralleled each other, whether the disease was in remission or not. Because of a selective increase of free hCG beta and free alpha in 27% of seminomatous tumor patients and in 13% of the nonseminomatous patients, the percentage of tumor-marker-positive sera was increased from 15% to 42% and 57% to 70%, respectively, by the additional measurement of free hCG beta and free alpha. Thus hCG, free hCG beta, and free alpha are physiologically present in a high percentage of the sera from healthy men, and the determination of free hCG beta and free alpha, although not of prognostic value, improves the diagnostic possibilities in patients with testicular cancer.
Practical Approach for Determining Glomerular Filtration Rate by Single-Injection Inulin Clearance
Authors: Jung K , Henke W , Schulze B D , Sydow K , Precht K , Klotzek S 
Published: January 2020

Abstract
We compared the glomerular filtration rate as measured by a single-injection inulin clearance with that measured by a standard isotope method with 99mTc-labeled diethylenetriaminopentaacetic acid in 21 subjects with glomerular filtration rates greater than 35 mL/min. After a bolus injection of 5 g of inulin, blood samples were taken 20, 45, 90, 120, 145, 180, and 240 min afterwards. Inulin was measured by optimized chemical or enzymatic methods of high analytical sensitivity to determine inulin at low concentrations. We used the one-compartment model and inulin concentrations measured at two sampling times to calculate the glomerular filtration rate from the data of the disappearance curve of inulin. Inulin concentrations at 20 and 240 min after injection of the inulin bolus were suited to estimate glomerular filtration rate by this procedure, resulting in values (y) comparable with those obtained by isotope technique (x). The relationship to the isotope technique was characterized by the equation y = +4.80 mL/min + 0.92x (r = 0.97). The single-injection inulin clearance determination can detect a decrease of glomerular filtration rate at the beginning of kidney damage, given that our study included subjects with glomerular filtration rates greater than 35 mL/min. We conclude that the glomerular filtration rate can be determined by analyzing only two blood samples after a bolus injection of inulin.
Plasma Methadone Measurements and Their Role in Methadone Detoxification Programs
Authors: Wolff K , Hay A W , Raistrick D 
Published: January 2020

Abstract
We monitored eight patients who were receiving a decreasing dose of methadone for treatment for opioid addiction (detoxification). Patients with plasma concentrations of methadone less than 0.05 mg/L experienced withdrawal symptoms, relapsed, and re-abused illicit drugs. Four patients took extra methadone (illicitly obtained) during detoxification. None of the eight patients in our study were successfully weaned off methadone: all left the methadone detoxification program before the completion of treatment. Two patients subsequently returned to a fixed methadone program elsewhere, and four relapsed and returned to illicit drug misuse. Plasma measurements may help clinicians assess patients during methadone detoxification.
High Incidence of Significant Urinary Ascorbic Acid Concentrations in a West Coast Population—Implications for Routine Urinalysis
Authors: Brigden M L , Edgell D , McPherson M , Leadbeater A , Hoag G 
Published: January 2020

Abstract
Examination of 4379 routine urinalysis specimens with dipsticks sensitive to ascorbic acid showed that 22.8% were positive specimens. The mean urinary vitamin C concentration in this population was 2120 mumol/L. There was a high rate of false-negative dipstick results for hemoglobin in patients with vitamin C in the urine. The highest false-negative rates were observed in urine samples containing less than 50 erythrocytes per high-power field. In further experiments when volunteers consumed supplemental oral USP vitamin C at doses of 100, 250, 500, and 1000 mg or vitamin C-containing fruit juices, even the lowest doses of oral vitamin C or juice resulted in sufficient urinary vitamin C to produce false-negative dipstick results in hemoglobin and glucose testing. To prevent potentially dangerous false-negative results, screening urinalysis protocols relying only on dipstick testing should include a check for urinary vitamin C or use a dipstick that is not subject to vitamin C interference.
Are Clinical Laboratory Proficiency Tests as good as They Can Be?
Authors: Tietz N W , Rodgerson D O , Laessig R H 
Published: January 2020

Abstract
Present proficiency test services that use the peer group mean and statistically derived ranges of acceptability are not serving us optimally and are even counterproductive in some respects. We recommend that the target value be determined by a widely accepted reference method and that acceptable ranges be based on criteria related to clinical need. This approach was adopted several years ago in Germany and has already eliminated the use of several unsatisfactory analytical methods. Because the transition would probably take many years, we propose an interim solution to allow instrument manufacturers and laboratorians to adapt to these changes. The current peer group means and acceptable ranges should be supplemented by reference method values and acceptable ranges, based on clinical need, so that manufacturers and laboratorians can judge their performance against these new criteria and make the necessary adjustment in instrumentation and methodology. These processes should be paralleled by efforts to produce proficiency test materials that will not exhibit the matrix problems of present-day preparations.
Evaluation of the Rigor and Appropriateness of CLIA '88 Toxicology Proficiency Testing Standards
Authors: Jenny R W , Jackson K Y 
Published: January 2020

Abstract
The proposed rule for the Clinical Laboratory Improvement Amendments of 1988 (CLIA '88) describes uniform standards for the design of proficiency testing (PT) challenges and for the evaluation of laboratory performance. Successful performance on PT is a condition for laboratory certification by the federal Department of Health and Human Services. We conducted a retrospective evaluation of PT data collected from laboratories participating in the New York State therapeutic substance monitoring/quantitative toxicology PT program to determine how well laboratories performed by proposed PT standards. We found that the unsuccessful performance rate is very low (less than 0.4%) and that laboratories providing limited services are more susceptible to program sanctions than are full-service laboratories. The performance criteria are empirically fixed limits that are not consistent with either the state of practice or the analytical goals based on clinical requirements for good patient care. We suggest that the performance standards, if adopted, would be a weak challenge to the capability of today's therapeutic drug monitoring service and will not provide the impetus to bring analytical performance characteristics into full compliance with analytical goals.
Diagnosis of α-Mannosidosis by Measuring α-Mannosidase in Plasma
Authors: Prence E M , Natowicz M R 
Published: January 2020

Abstract
alpha-Mannosidosis is a lysosomal storage disease resulting from a deficiency of lysosomal alpha-mannosidase activity. Diagnosis of alpha-mannosidosis has traditionally been accomplished by demonstrating reduced alpha-mannosidase activity in leukocytes. We describe a new assay of alpha-mannosidase in serum or plasma that allows specific detection of the enzyme deficiency in alpha-mannosidosis with small, easily obtained sample volumes. The assay utilizes 40 microL of serum or plasma and a fluorescent substrate, 4-methylumbelliferyl-alpha-D-mannopyranoside in sodium acetate buffer, pH 4.0. The mean activity of a control population was 194 (SD 67) mU/L, whereas the activities obtained for four alpha-mannosidosis patients were 0, 17, 17, and 33 mU/L. Comparison with the standard leukocyte alpha-mannosidase assay showed this serum or plasma assay to be equally effective in diagnosing alpha-mannosidosis.
Enzymatic Assay of Inorganic Phosphate with Use of Sucrose Phosphorylase and Phosphoglucomutase
Authors: Tedokon M , Suzuki K , Kayamori Y , Fujita S , Katayama Y 
Published: January 2020

Abstract
We developed a new enzymatic method for the assay of inorganic phosphate (Pi) by using sucrose phosphorylase (SP; EC 2.4.1.7) and phosphoglucomutase (PGM; EC 5.4.2.2). Pi is transferred to sucrose by SP, producing alpha-D-glucose 1-phosphate (G1P) and alpha-D-fructose. G1P is transphosphorylated by PGM in the presence of alpha-D-glucose 1,6-bisphosphate to form alpha-D-glucose 6-phosphate, which is oxidized by NAD+ and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) to form 6-phosphogluconate (6PG) and NADH. Finally, the oxidation of 6PG by NAD+, catalyzed by 6-phosphogluconic dehydrogenase (EC 1.1.1.44), yields D-ribulose 5-phosphate and NADH. Thus two molecules of NADH are formed for each molecule of Pi, and the reaction is monitored at 340 nm. The Km values of SP for Pi and sucrose were 4.44 and 5.31 mmol/L, respectively. The best buffer was 1,4-piperazinediethanesulfonic acid (PIPES) at 50 mmol/L and pH 6-7. Implementing this method with a Cobas-Bio centrifugal analyzer allowed us to measure Pi accurately and precisely.
New Chromogen for Assay of Glucose in Serum
Authors: Reljic R , Ries M , Anić N , Ries B 
Published: January 2020

Abstract
We describe a colorimetric assay for glucose determination in human serum, with use of the chromogen 2-amino-4-hydroxybenzenesulfonic acid (AHBS), glucose oxidase, and peroxidase. With this assay, glucose concentrations less than or equal to 27.8 mmol/L can be measured in serum, with a sample/reagent volume ratio as low as 0.0025. The chromogen itself is easily soluble in water and does not require other components for the color change, making the reagent composition less complex. A single working reagent is used, and the reaction is completed within 10 min at 37 degrees C. The absorbance of the yellow reaction product is measured at 415 nm, and a blank sample measurement is not needed. The average analytical recovery of glucose in different human sera was 97.6%, with no significant interference of reducing compounds in serum. The results of the recommended procedure correlated well with those of the phenol/4-aminoantipyrine method of Trinder.
Pediatric and Perinatal Reference Intervals for Immunoglobulin Light Chains Kappa and Lambda
Authors: Herkner K R , Salzer H , Böck A , Mühl A , Tsaka T , Steger H , Pollak A , Schatten C , Popp W , Huber-Spitzy V 
Published: January 2020

Abstract
In routine analysis for immunoglobulin light chains in pediatric diagnostics, the age-related reference intervals for serum kappa (kappa) and lambda (lambda) light chains were evaluated in 1543 healthy subjects (newborns to age 16 years, including 168 premature infants). Light-chain analysis was performed by rate nephelometry. IgG, IgA, and IgM were measured simultaneously, and heavy- and light-chain differences were calculated for control purposes. Results for IgG, IgA, and IgM generally agreed with reference intervals reported in the literature. kappa showed age-related changes comparable with changes in IgG concentrations, whereas lambda showed moderate fluctuations. The kappa/lambda ratio showed an almost linear increase with age, starting with 0.97 at four months and reaching the highest value of 2.21 at 15 years (mean values). Preterm infants presented with markedly low serum concentrations of IgG and corresponding light chains but with adult-type kappa/lambda ratios because of the maternal-origin IgG.
Complexation of Iron with the Orally Active Decorporation Drug L1 (3-Hydroxy-1,2-Dimethyl-4-Pyridinone)
Authors: Kline M A , Orvig C 
Published: January 2020

Abstract
The stability constants for the Fe(III) complexes of the orally active iron decorporation drug L1 (3-hydroxy-1,2-dimethyl-4-pyridinone) have been determined by potentiometric titration [glass electrode, 25.0 degrees C, mu = 0.15 mol/L (isotonic) NaCl]. A simple computer model of blood plasma (citrate 100 mumol/L, transferrin 37 mumol/L) has been used to compare the Fe(III) binding efficacies in blood of L1 and the clinically used intravenously administered chelating agent deferoxamine.
Normal Variation of Plasma Lipoproteins: Postural Effects on Plasma Concentrations of Lipids, Lipoproteins, and Apolipoproteins
Authors: Miller M , Bachorik P S , Cloey T A 
Published: January 2020

Abstract
We examined the effects of postural change on the concentrations of plasma cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, apolipoproteins (apo) A-I and B, and lipoprotein(a) [Lp(a)] in six volunteers who fasted 12 h before blood sampling. Baseline samples were drawn in the standing position; the subjects then assumed the supine or sitting position, and additional blood samples were drawn at intervals up to 40 min. They then returned to the standing position and were again sampled at intervals up to 40 min. In the supine position, lipid, lipoprotein, and apolipoprotein concentrations decreased rapidly within the first 5 min and stabilized after 20 min. Total and HDL cholesterol, apoA-I, apoB, and Lp(a) decreased by as much as 7-12% in the supine position and returned to baseline values 20-40 min after the standing position was resumed. Smaller changes (5-9%) were observed when the subjects were sitting, and returned to baseline within 20 min after the subjects resumed the standing position. The decrease in triglycerides was 17% in the supine position and 10-11% in the sitting position. Lp(a) concentrations decreased 7-8% in either the supine or sitting position and returned to baseline more slowly than did the other components. For all components the changes were most rapid within the first 10 min after changing posture.
Rapid Immunometric Measurement of C-Reactive Protein in Whole Blood
Authors: Urdal P , Borch S M , Landaas S , Krutnes M B , Gogstad G O , Hjortdahl P 
Published: January 2020

Abstract
We examined an instrument-free test for C-reactive protein (CRP) in whole blood. The NycoCard CRP Whole Blood test uses a cell-solubilizing dilution liquid, a membrane-bound antibody that binds CRP, and a gold-conjugated antibody for making visible the bound CRP. We obtained essentially identical dose-response curves in citrate-, heparin-, and EDTA-treated blood. CVs were 6.7-12.5% within series and 10.1-14.7% between series. The detection limit was 12 mg/L. Intralipid added to blood increased measured CRP by 10-20%, whereas no change was seen with added bilirubin, added serum amyloid P component, or the presence of rheumatoid factor. In 234 patients' blood samples the results of the NycoCard Whole Blood test correlated well (r = 0.96) with those of a turbidimetric serum method. The test allows reliable measurement of CRP from a small volume of whole blood (25 microL) without using expensive equipment; it should be useful for decentralized testing in hospital departments, emergency units, and primary health care centers.
Proficiency Testing from a Total Quality Management Perspective
Authors: Castañeda-Méndez K 
Published: January 2020

Abstract
Public concern over increasing health-care costs plus dramatized testing errors, has resulted in CLIA '88 with its more stringent rules governing laboratory performance. The purpose of the 1990 U.S. Health Care Financing Administration Final Rules for Proficiency Tests is to separate the quality laboratory from the poorly performing one. From the perspective of total quality management, the customer (patient) defines quality as virtually error-free test results. The current proficiency testing format defeats this. Its effective purpose is not to identify quality laboratories but to shut down the most prolific laboratories--regardless of their quality. There are two reasons for this. First, the proficiency testing format is incomplete: it is missing a minimum frequency criterion. Second, the data for determining the quality of a laboratory's performance (the degree of error-free results) are not being used. I propose a solution based on continuous improvement that promotes voluntarism, favors the quality laboratory, and reduces federal regulation.
Reference Intervals for Eight Modified Nucleosides in Serum in a Healthy Population from Italy and the United States
Authors: Pane F , Oriani G , Kuo K C , Gehrke C W , Salvatore F , Sacchetti L 
Published: January 2020

Abstract
We used a recently devised HPLC method to quantify eight modified nucleosides, an emerging group of tumor markers, in human serum and then calculated their reference intervals in a healthy population from Italy and the United States. We used the statistical procedure of element analysis, which reveals the effects of chosen variables (in this case, nationality, sex, and age) on an analyte (here, modified nucleosides). Using element analysis, we calculated the exact weight of each variable on the reference values. We found that nationality has the greatest effect on the serum concentrations of all the modified nucleosides apart from pseudouridine, whereas sex significantly influences only the concentrations of 4-pyridone-3-carboxamide-N1-ribofuranoside, 1-methylinosine and N2,N2-dimethylguanosine; age affects only N2,N2-dimethylguanosine. Thus, the reference intervals of all the nucleosides except pseudouridine were calculated separately for Italians and Americans, and the reference values for 4-pyridone-3-carboxamide-N1-ribofuranoside, 1-methylinosine, and N2,N2-dimethylguanosine were calculated separately for men and women. Our data form the baseline for study of variations in serum concentrations of modified nucleosides in various pathophysiological conditions.
Comparison of Methods for Measuring Free Thyroxin in Nonthyroidal Illness
Authors: Wong T K , Pekary A E , Hoo G S , Bradley M E , Hershman J M 
Published: January 2020

Abstract
Patients with severe nonthyroidal illness (NTI) often have decreased serum thyroxin (T4) concentrations and sometimes have decreased free T4 (FT4) and increased tumor necrosis factor-alpha (TNF-alpha) concentrations. We evaluated four commercial methods for measuring FT4 [Abbott IMx, Amersham Amerlex MAB, Nichols, and Diagnostic Products Corporation (DPC) RIA] and one method for TNF-alpha in 41 NTI patients, 24 euthyroid control subjects, and 10 hypothyroid patients. Free T4 index (FTI) was also measured by the Abbott IMx method. Euthyroid subjects results were in the stated normal ranges. NTI FT4 was subnormal in 2.4%, 61%, and 29% by the Nichols, DPC, and Amerlex methods, respectively. The DPC, Amersham Amerlex, and Abbott IMx methods gave significantly lower FT4 values for the NTI group than for the controls. There were good correlations between the various FT4 methods in the NTI group. FTI concentrations correlated well with FT4 for the euthyroid and hypothyroid groups but poorly for the NTI group. The Abbott IMx and Nichols RIA methods yield values in the hypothyroid range for only a small proportion of NTI patients.
Quantification of Islet Cell Antibodies by Microscope Photometry and Antibody Titration Compared
Authors: Bright G M 
Published: January 2020

Abstract
Islet cell antibodies can predict eventual insulin-dependent diabetes mellitus. In the standard method used by the Immunology of Diabetes Workshop (IDW), predictive power depends on antibody titer as determined by testing multiple serum dilutions. Here I report use of a microscope-based photometry system (MPS) to test whether islet fluorescence intensities from undiluted sera can predict IDW results. MPS testing of 120 undiluted IDW specimens correctly identified 27 of 31 positive and 84 of 89 negative specimens. The relationship between IDW consensus values and MPS readings of undiluted sera is: IDW = 2.45 MPS - 1.44 (r = 0.67, P less than 0.001). Thus, corrected islet intensities from undiluted sera correlated well with IDW values. However, the ability of MPS to predict high IDW consensus values is limited, which may reflect the variable antigenic content of pancreas specimens; moreover, background correction as currently applied is incomplete; nonspecific immunofluorescence appears to emanate from within the islet.
Ultrasensitive Radioimmunoassay of Prostate-Specific Antigen
Authors: Graves H C , Wehner N , Stamey T A 
Published: January 2020

Abstract
We describe a modification of the Yang Pros-check radioimmunoassay for prostate-specific antigen (PSA) that increases the analytical sensitivity of the assay approximately threefold (from a working range of 0.3-50 to 0.1-1.2 micrograms/L). It can detect PSA added to zero-concentration diluent (bovine serum albumin solution) at 0.10 microgram/L or added to zero-concentration control female serum at 0.20 microgram/L (P less than 0.05). In 26 patients tested after cystoprostatectomy for bladder cancer (who had normal prostates without cancer on histologic examination), PSA values by this ultrasensitive assay were all less than 0.10 microgram/L. Therefore, we propose this value as the upper limit of the 95% reference interval. In a retrospective study of two patients who developed recurrent prostate cancer, serum PSA values increased above the 0.1 microgram/L detection limit 175 and 581 days before increasing above the 0.3 microgram/L detection limit of the standard Yang assay. This ultrasensitive radioimmunoassay of PSA should prove more useful than current methods for detecting early recurrence of prostate cancer.