bluuebunny/crossref_metadata_2025_split huggingface dataset:
Commercial assays for serum osteocalcin give clinically discordant results
Authors: Masters P W , Jones R G , Purves D A , Cooper E H , Cooney J M 
Published: January 2020

Abstract
Serum samples from 9 healthy controls and from subjects with primary hyperparathyroidism (n = 5), Paget disease (n = 3), pregnancy (n = 5), glucocorticoid therapy (n = 5), postmenopausal osteoporosis (n = 10), and renal failure (n = 10) were used to assess the clinical agreement among eight commercially available assay kits for osteocalcin (OC). These kits differ in their assay configurations (six radioimmunoassays, two immunoradiometric assays), standards (five bovine, three human), and antibodies (six polyclonal, two monoclonal). Individual results were divided by the mean OC of the control subjects for each assay and expressed as percentage deviations. The expected wide variation in absolute OC concentrations between kits was only partially reduced by this transformation. Agreement was equally poor when absolute OC concentrations were compared with the reference ranges quoted by the manufacturers. The discordance was particularly marked in renal failure, presumably because of immunoreactive fragments, and in osteoporosis. Systematic differences could not be attributed to assay format, species source of standard, or antibody specificity. We conclude that results cannot be compared between assays even when normalized against healthy subjects, and that standardization is needed.
Hematofluorometric determination of erythrocyte zinc protoporphyrin: oxygenation and derivatization of hemoglobin compared
Authors: Louro M O , Tutor J C 
Published: January 2020

Abstract
We compared oxygenation and derivatization of hemoglobin for the hematofluorometric determination of erythrocyte zinc protoporphyrin (ZPP). No statistically significant differences were found when the volume ratio of sample to ProtoFluor reagent (which converts hemoglobin to cyanohemoglobin) was changed from 1:1 to 1:4. With the derivatizing reagent, results were significantly higher than those obtained after thorough aeration of the blood sample (P &lt; 0.001). The differences between the results obtained by the two procedures were greater for ZPP values in the reference range. Although the correlation between methods was high (r = 0.997), interconversion of the results by means of the regression equation was not acceptable because the standard error of the estimate from the regression (Syix = 0.36 micrograms/g hemoglobin) was greater than the error acceptable medically (criterion of Harris: Arch Pathol Lab Med 1988; 112:416-20).
Detecting benzodiazepines: immunoassays compared with negative chemical ionization gas chromatography/mass spectrometry
Authors: Fitzgerald R L , Rexin D A , Herold D A 
Published: January 2020

Abstract
We tested 231 urine samples by six immunoassay methods--EMIT d.a.u., EMIT II, Roche Abuscreen Online, Abbott TDx, Diagnostic Products Corp. (DPC) double-antibody radioimmunoassay (RIA), and Biosite Triage--and by negative chemical ionization gas chromatography/mass spectrometry to determine how the immunoassays performed on samples selected for suspected benzodiazepine use (n = 100) and in random urine drug screening (n = 131). In general, all of the assays were successful in detecting oxazepam and related metabolites, even at concentrations below the stated cutoffs. However, the negative predictive value of benzodiazepine immunoassays for samples selected for suspected benzodiazepine use ranged from 86% to 96%. A primary difference between the test kits was the ability of DPC RIA and Triage to detect lorazepam when other assays did not. Contrary to previous reports, pretreatment of specimens with glucuronidase was not necessary to detect oxazepam-related metabolites with these immunoassays.
Enzymatic diagnosis of aspartylglycosaminuria by fluorometric assay of glycosylasparaginase in serum, plasma, or lymphocytes
Authors: Mononen I , Mononen T , Ylikangas P , Kaartinen V , Savolainen K 
Published: January 2020

Abstract
Serum, plasma, and lymphocytes from aspartylglycosaminuria (AGU) patients and carriers and from normal controls were incubated with a fluorescent glycosylasparaginase substrate, L-aspartic acid beta-(7-amido-4-methylcoumarin), and the release of 7-amino-4-methylcoumarin was measured fluorometrically after incubation for 1-4 h. The mean glycosylasparaginase (EC 3.5.1.26) activity in normal serum, plasma, and lymphocytes was 20.2 (SD 5.0) mU/L (n = 24), 17.5 (SD 5.0) mU/L (n = 24), and 242 (SD 108) mU/g protein (n = 17), respectively. The corresponding values in the Finnish AGU patients were 0.7 (SD 0.4) mU/L (n = 10), 0.3 (SD 0.3) mU/L (n = 10), and 6.0 (SD 4.6) mU/g protein (n = 7). No overlapping values were obtained between the AGU patients and the carriers in any of the samples, but the values between the carriers and controls were overlapping in 28 of 29 serum, 22 of 29 plasma, and 4 of 21 lymphocyte samples. Thus, the fluorometric glycosylasparaginase assay in various blood samples allows specific detection of the enzyme defect in AGU, but cannot be used for reliable detection of carriers of the disease.
Limitations of the Friedewald formula for estimating low-density lipoprotein cholesterol in alcoholics with liver disease
Authors: Matas C , Cabré M , La Ville A , Prats E , Joven J , Turner P R , Masana L , Camps J 
Published: January 2020

Abstract
The accuracy of the Friedewald formula in estimating low-density lipoprotein (LDL) cholesterol was investigated in 47 alcoholic patients with liver disease (21 minimal-change, 26 cirrhotic) by comparing the results with those obtained by sequential preparative ultracentrifugation. In 14% of subjects with minimal-change disease, the error in the estimated LDL cholesterol was 50% +/- 9% (mean +/- SD; range 40-59%) and was related to the degree of attendant hypertriglyceridemia (r = 0.98; P &lt; 0.001). A similar degree of error was observed in patients with cirrhosis, despite the absence of hypertriglyceridemia; an abnormal VLDL cholesterol: triglyceride ratio was the contributory factor in the discrepancy. We conclude that, as is the case in other clinical pathologies in which abnormalities of lipoprotein composition have been described (e.g., diabetes), the Friedewald formula to estimate LDL cholesterol may be inappropriate in chronic alcoholics, particularly those in whom a degree of hepatic dysfunction may be suspected.
Retinol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, trans-beta-carotene, and four retinyl esters in serum determined simultaneously by reversed-phase HPLC with multiwavelength detection
Authors: Sowell A L , Huff D L , Yeager P R , Caudill S P , Gunter E W 
Published: January 2020

Abstract
We describe the use of HPLC with multiwavelength detection to measure retinol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, trans-beta-carotene, beta-carotene, and the linoleate, oleate, palmitate, and stearate esters of retinol in a single 200-microL serum sample. The method is sensitive enough to detect individual retinyl esters in fasting serum from a nonhyperlipidemic population and requires only 12 min for each sample. Serum concentration ranges and means are reported for retinol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, trans-beta-carotene, and the sum of the retinyl esters from serum analyses of 3480 participants from several different studies.
Measurement of gonadotropins in dried blood spots
Authors: Worthman C M , Stallings J F 
Published: January 2020

Abstract
We describe direct immunofluorometric assays for luteinizing hormone (hLH) and follicle-stimulating hormone (hFSH) in fingerstick blood spots dried on filter paper, based on modifications of commercially available kits. Determinations are made from 2.5-mm-diameter discs (3 microL of dried blood) punched out from blood spot standards and samples. Sample dose detection limits of the assays (IU/L) are 0.26 for LH and 0.13 for FSH, with mean interassay CVs of 11.6% (LH) and 7.8% (FSH) at low concentrations. Analytical recoveries of added hormone averaged 100% for LH and 95% for FSH. Clinical studies showed that values for blood spots (x) and directly assayed plasma (y) are highly correlated, so that results from blood spots can be converted directly to plasma equivalents, as follows: yLH = 0.07 + 1.90 xLH, and yFSH = 0.424 + 2.207 xFSH. These gonadotropins are stable in blood spots for at least a year under refrigeration; LH for at least 8 weeks and FSH 6 weeks at 22 degrees C; and both hormones for a week at 37 degrees C. These methods thus allow self-sampling, serial sampling, and mailing of specimens.
Early detection of metabolic abnormalities in preterm infants impaired by disorders of blood glucose concentrations
Authors: Lyall H , Burchell A , Howie P W , Ogston S , Hume R 
Published: January 2020

Abstract
We recently reported (Acta Paediatr Scand 1992;8: 580-4) three preterm infants with severe respiratory distress syndrome and abnormal glucose profiles for the first 5 days of life who subsequently died in infancy; only at autopsy were they shown to have abnormal glucose-6-phosphatase activity. We have therefore studied retrospectively in a matched cohort of 109 infants the blood glucose profiles correlated with the severity of respiratory distress syndrome (expressed as the fraction of inspired oxygen, FiO2): group A, mild, FiO2 &lt; 0.25; group B, moderate, FiO2 0.26-0.50; group C, severe, FiO2 &gt; 0.51. All groups had a similar frequency of low blood glucose values (15% &lt; or = 2.2 mmol/L; 29% &lt; or = 2.6 mmol/L), but high blood glucose values and greater variability in glucose values were more common in groups B and C despite lower caloric intakes (A, 4.3%; B, 9.3%; C, 9.6% &gt; or = 7 mmol/L). We conclude that the early blood glucose patterns in those three previously described preterm infants with abnormal hepatic glucose-6-phosphatase activity at autopsy cannot be viewed as abnormal when considered against a matched cohort of infants. Preterm infants at risk of genetic or developmental delays in blood glucose homeostasis should be reassessed after recovery from their acute illnesses.
Different forms of insulin-like growth factor-binding protein-3 detected in serum and seminal plasma by immunofluorometric assay with monoclonal antibodies
Authors: Koistinen H , Seppälä M , Koistinen R 
Published: January 2020

Abstract
Monoclonal antibodies against recombinant insulin-like growth factor-binding protein-3 (IGFBP-3) were produced to study the various forms of IGFBP-3 and to develop a specific immunofluorometric assay. We tested seven antibodies that showed no cross-reactions with the other five human IGFBPs. By immunoblotting, the main bands in normal serum were seen at &gt; 90, 45, 41, 29, and 25 kDa. In pregnancy serum, the 29-kDa was stronger, and the double band at 41-45 kDa was weaker or totally absent. We characterized two immunofluorometric assays. IGF-I had no effect on either assay. Added IGF-II lowered the amount of recombinant IGFBP-3 measured by the 5C11/7F8 assay, but not by the 1B6/5C11 assay. In normal serum and follicular fluid, IGFBP-3 measurements were lower by the 5C11/7F8 assay, but in most pregnancy sera and amniotic fluids the assays gave similar results. The 5C11/7F8 assay also detected IGFBP-3 in seminal plasma, whereas the 1B6/5C11 assay did not. We conclude that the results of IGFBP-3 measurement depend on the antibodies used, and that different antibodies are suitable for the IGFBP-3 measurement in different body fluids.
When is a serum iron really a serum iron? The status of serum iron measurements
Authors: Tietz N W , Rinker A D , Morrison S R 
Published: January 2020

Abstract
Although serum iron determinations play an important role in the diagnostic process, the accuracy of routine methods is suspect. The poor performance of currently used methods is well documented in the quarterly College of American Pathologists survey reports. Compared with the 1990 method of the International Committee for Standardization in Haematology (ICSH), the 1978 ICSH Reference Method shows a +3.4% bias and the standard method of the National Committee for Clinical Laboratory Standards shows a -17.8% bias for iron results. All routine methods checked--DuPont aca, Abbott TDx, Kodak Ektachem (except one lot), BM/Hitachi 717, and Synermed--show a negative bias over the entire analytical range, a significant negative intercept, and extremely poor correlation with the 1990 ICSH method for iron values &lt; 750 micrograms/L. Individual discrepancies of several hundred percent were observed. Imprecision of the methods is not the reason for these discrepancies. We question whether most routine methods measuring low iron concentrations provide results sufficiently reliable for confirmation of iron deficiency.
Replacing creatinine measurements with specific gravity values to adjust urine cotinine concentrations
Authors: Haddow J E , Knight G J , Palomaki G E , Neveux L M , Chilmonczyk B A 
Published: January 2020

Abstract
Creatinine and specific gravity (relative density) measurements both allow differences in urine concentration to be taken into account in determining urine cotinine concentrations. In this study we demonstrate that the variance of urine cotinine measurements is reduced comparably when either creatinine or specific gravity measurements are used for correction. This reduction in variability improves the correlation between urine cotinine measurements and clinical endpoints. In this study, the clinical endpoints were pulmonary function in a population of nonsmoking children with asthma, 42% of whom were reported to have been exposed to environmental tobacco smoke. When corrected by either creatinine measurements or specific gravity values, the urine cotinine measurements performed as well or better than reported exposure (and comparably with each other) in assessments of lung function. A dose-response relationship was also more consistently apparent. Specific gravity values can be used reliably in place of creatinine values to adjust urine cotinine measurements for both research and clinical purposes.
Citrate as the main small molecule binding Al3+ in serum
Authors: Ohman L O , Martin R B 
Published: January 2020

Abstract
A recent proposal (Clin Chem 1992;38:1809-18) that inorganic phosphate is the predominant small molecule binding Al3+ in blood serum is shown to be incorrect. Experiments in which Al3+ is added to solutions containing phosphate and citrate in the same proportions as in serum clearly show that citrate prevents formation of any aluminum phosphate precipitate, and analysis of these data indicates that the assumed binding constants for soluble phosphate are two orders of magnitude too strong. Consideration of the effect of competitive binding of alkaline earth metal ions to citrate on Al3+ binding and of a set of transferrin-Al3+ stability constants leads to the conclusion that the proportions are in close agreement with previously published results. We conclude on the basis of stability constants that, of the Al3+ in blood serum, approximately 89% (+/- 5%) binds to transferrin and approximately 11% (+/- 5%) to citrate.
Simultaneous determination of mercury speciation in biological materials by GC/CVAFS after ethylation and room-temperature precollection
Authors: Liang L , Bloom N S , Horvat M 
Published: January 2020

Abstract
We developed a method for the simultaneous determination of monomethyl mercury (MMHg), inorganic mercury [Hg(II)], and total mercury (THg) in biological materials. A variety of biological materials can be digested in methanolic KOH solution. The MMHg and Hg(II) present are converted to volatile ethyl derivatives, methylethyl mercury and diethyl mercury, by an aqueous-phase ethylation reaction with sodium tetraethylborate. The ethyl derivatives are precollected onto a trapping column at room temperature, in case of disconnection with the separation/detection system, and then thermally desorbed into a packed isothermal gas chromatography (GC) column. Eluted organo-Hg compounds from the GC column are decomposed into Hg0, and detection is completed by cold vapor atomic fluorescence spectrometry (CVAFS). Pure standard solutions can be used for calibration. The sum of MMHg and Hg(II) obtained by this method equals the THg value obtained by digestion with HNO3 and H2SO4, reduction with SnCl2, and single-stage amalgamation/CVAFS for all biological materials studied. Absolute detection limits are 0.6 pg and 1.3 pg of Hg as MMHg and Hg(II), respectively, corresponding to 0.3 ng and 0.6 ng/g (wet) of sample.
Steady-state concentration of cyclosporin G (OG37-325) and its metabolites in renal transplant recipients
Authors: Langman L J , Leichtman A B , Weitzel W F , Yatscoff R W 
Published: January 2020

Abstract
The steady-state concentrations of cyclosporin G (OG37-325) (CsG) and six of its metabolites (GM1, GM9, GM4N, GM1c, GM1c9, GM19) were measured throughout the 12-h dosing interval in six renal transplant recipients receiving CsG as prophylaxis against acute cellular rejection. The mean 12-h whole-blood trough concentrations (micrograms/L) were CsG, 131 +/- 26; GM1, 79 +/- 55; GM9, 110 +/- 114; GM4N, 28 +/- 18; GM1c, 31 +/- 18; GM1c9, 216 +/- 145; and GM19, 303 +/- 217. The relative concentration of the primary metabolites (GM1, GM9, GM4N) remained stable with respect to CsG throughout the dosing interval, whereas that of the secondary metabolites increased. The secondary metabolites GM19 and GM1c9 exhibited extensive between-patient variation. We investigated the effect of these metabolites on commercially available monoclonal antibody-based fluorescence polarization immunoassays (FPIA) and RIAs adapted for measurement of CsG. The 12-h whole-blood trough concentrations measured by FPIA and RIA exceed those measured by HPLC by 19% and 36%, respectively. These measured biases corresponded closely with the calculated biases (FPIA 19%, RIA 28%) based on the known cross-reactivities of CsG metabolites and their concentrations. These results suggest that cross-reactivity with metabolites account for a large part of the bias observed in immunoassays of CsG.
Human urinary arsenic excretion after one-time ingestion of seaweed, crab, and shrimp
Authors: Le X C , Cullen W R , Reimer K J 
Published: January 2020

Abstract
We studied chemical speciation of arsenic compounds in urine samples by using HPLC with inductively coupled plasma mass spectrometry detection. We examined urinary arsenic excretion patterns and the arsenic species excreted from nine human subjects who ingested seaweed products and crab (or shrimp). Fast urinary excretion of unchanged arsenobetaine was seen after ingestion of crab and shrimp, which contain arsenobetaine as the major arsenic species. In contrast, the arsenosugars, which comprise the major arsenic species in seaweed, are metabolized and have a longer retention time in the human body. When nine volunteers ingested the commercial seaweed product nori, both the urinary arsenic excretion pattern and the excreted arsenic species varied from individual to individual, and as many as six metabolites could be detected. It seems that arsenosugars are not decomposed by stomach acid and that reactions involving enzymatic and (or) microbial activity in the human body may be responsible for the metabolism of arsenosugars.
Two-site immunoassay of recombinant hirudin based on two monoclonal antibodies
Authors: Mille B , Condamines O , Herbert J M , Maftouh M , Picard C , Dussossoy D , Pau B 
Published: January 2020

Abstract
Two monoclonal antibodies (mAbs), 10-2 and 10-5, both directed against recombinant hirudin variant 2-Lys47 (rHV2), were selected for their high affinity and epitopic specificities to develop a two-site immunoassay of rHV2. The mAb concentrations, incubation time, and temperature were optimized. The immunoassay has a detection limit for rHV2 of 45 ng/L in plasma and 30 ng/L in urine. The reactivity of the mAbs was tested against rHV2 and several forms of this protein truncated in the carboxyl terminus. The capture mAb 10-2 was found to be mainly directed against rHV2, whereas tracer mAb 10-5 was independent of the carboxyl-terminal region of the protein. This explains the high specificity of the immunoassay for the 65-amino acid form of hirudin.
Measurement of felbamate by wide-bore capillary gas chromatography and flame ionization detection
Authors: Rifai N , Fuller D , Law T , Mikati M 
Published: January 2020

Abstract
Felbamate, a newly developed antiepileptic agent, has been demonstrated to control partial and generalized seizures effectively. We have developed a gas-chromatographic method for the determination of felbamate, using a wide-bore capillary column, a flame ionization detector, and a simple extraction procedure. The assay day-to-day precision (n = 20) was 5.2% and 3.6% for drug concentrations of 50 and 150 mg/L, respectively; average recovery over a wide range of felbamate concentrations was 95%; the detection limit was 5 mg/L; and assay linearity extended to 300 mg/L. Although 9 of the 27 drugs tested were coextracted with felbamate, they exhibited significantly different retention times and showed no interference. A short-term stability study showed that plasma felbamate is stable at 4, -20, or -78 degrees C for at least 1 month. Plasma felbamate concentrations in 66 pediatric patients ranged from 7 to 154 mg/L (mean +/- SD 44 +/- 24.7). We consider the method ideally suited for therapeutic monitoring of plasma felbamate concentration.
New enzymatic assay of iron in serum
Authors: Fujita T , Hamasaki H , Furukata C , Nonobe M 
Published: January 2020

Abstract
A new enzymatic method for assaying iron in serum samples, suitable for automated analyzers, is reported. Three reagent mixtures are used: dilution buffer (pH 3.0; ascorbate), reagent 1 (pH 6.7; apoaconitase), and reagent 2 (pH 7.7; citrate, magnesium, and isocitrate dehydrogenase). Sera are diluted with dilution buffer. Fe3+ is liberated from transferrin in sera under acidic conditions, and then reduced by ascorbate. Reagent 1 is added to diluted specimens, and apoaconitase is reactivated by Fe2+ at neutral pH. The resulting solutions are mixed with reagent 2, so that holoaconitase hydrolyzes citrate to isocitrate and the isocitrate and NADP+ are converted to 2-oxoglutarate, NADPH, and CO2. Serum iron is determined linearly up to 70 mumol/L, with within-run CVs &lt; or = 2.4% and day-to-day CVs &lt; or = 2.9%. This method (y) gives results correlating with those of a Reference Method (x) proposed by the International Committee for Standardization in Haematology: y = 0.98x + 0.38 mumol/L (n = 72, r = 0.996, Sylx = 0.63 mumol/L). The mean (+/- SD) serum iron concentrations measured by our method were 18.5 +/- 5.4 and 15.2 +/- 6.0 mumol/L for 63 males and 166 females, respectively.