bluuebunny/crossref_metadata_2025_split huggingface dataset:
Significance of low concentrations of creatinine in serum from hospital patients.
Authors: Hagemann P , Kahn S N 
Published: January 2020

Abstract
We present an analysis of the clinical significance of creatinine concentrations less than or equal to 4 mg/L (35 mumol/L) in serum as measured by a specific enzymatic method. In an unselected hospital patient population, 4% of whom had serum creatinine concentrations this low, a value of 5 mg/L (44 mumol/L) or higher was obtained on repeat analysis for a third of these patients, but the remaining two-thirds had persistently low values. Associated clinical conditions included low body mass, pregnancy, insulin-dependent diabetes mellitus, and total immobilization, but 12% of the patients, all female, had no obvious cause for the persistently low creatinine concentration. We conclude that low concentrations of creatinine in serum have no profound clinical significance.
Mobile laboratory unit based on the Kodak Ektachem DT system.
Authors: Pettigrew A R , Orrell J M , Dominiczak M H 
Published: January 2020

Abstract
We evaluated the Kodak Ektachem DT system (DT60, DTE, DTSC modules), using it as a mobile laboratory unit (MLU) in different hospital settings. Imprecision of 19 assays performed with the system and correlation with routine methods in the main laboratory were assessed. The system was then transported to different departments within the hospital, where limited test profiles were offered and the time taken to produce results was recorded. It proved practicable to offer a six-test electrolyte profile to a five-bed intensive-care unit but not to an 18-bed renal unit, where more selective analysis would be required. In a low-throughput outpatient clinic (five patients per hour) it was feasible to provide a six-test on-site profile on every patient, whereas the maximum number of tests was four in a high-throughput clinic (10 patients per hour). The cost of providing a flexible extra-laboratory biochemistry service must be balanced against the benefit of having on-site results, e.g., fewer outpatient-clinic visits.
Dual-precipitation method evaluated for determination of high-density lipoprotein (HDL), HDL2, and HDL3 cholesterol concentrations.
Authors: Dias V C , Parsons H G , Boyd N D , Keane P 
Published: January 2020

Abstract
We evaluated a dual-precipitation method for determining cholesterol in high-density lipoprotein (HDL) and its subfractions HDL2 and HDL3. After total HDL was isolated by precipitation of very-low-density (VLDL) and low-density (LDL) lipoproteins with polyethylene glycol (Mr 8000), HDL2 was isolated from total HDL by precipitation with dextran sulfate (Mr 15,000), leaving HDL3 in the supernate. Concentration of total HDL cholesterol after precipitation of VLDL and LDL with PEG showed significant proportional and constant biases of -3.8% and 0.04 mmol/L, respectively, when compared with a phosphotungstic acid-based comparison method, although results by the two methods were correlated highly (r = 0.99, P less than 0.001). HDL2 and HDL3 cholesterol concentrations measured with the present technique were not different from those obtained by density-gradient ultracentrifugation or by combined precipitation-ultracentrifugation.
Results compared for tricyclic antidepressants as assayed by liquid chromatography and enzyme immunoassay.
Authors: Dorey R C , Preskorn S H , Widener P K 
Published: January 2020

Abstract
The tricyclic antidepressants amitriptyline, nortriptyline, imipramine, and desipramine in serum of patients taking one of the drugs were quantified in two laboratories by high-performance liquid chromatography (HPLC) and enzyme-multiplied immunoassay (EMIT; Syva). Results for split samples were highly correlated, but EMIT gave higher results in most cases, and the slopes of the correlation lines for each analyte were greater than 1. Detection limits for the two procedures were such that 18% of the EMIT results for the drug(s) were considered negative, as compared with 4% of the HPLC results. Additional assay of desmethyl or hydroxy antidepressant metabolites by HPLC did not explain the higher EMIT results. The relatively high detection limit for EMIT greatly limits its use in therapeutic drug monitoring, where low concentrations of tricyclic antidepressants are as important as high ones for dose adjustment or determination of compliance. Other problems with EMIT measurement of tricyclic antidepressants are discussed.
Lipoprotein cholesterol concentrations in the plasma of human subjects as measured in the fed and fasted states.
Authors: Cohn J S , McNamara J R , Schaefer E J 
Published: January 2020

Abstract
Lipoprotein cholesterol concentrations in plasma are routinely estimated by using the Friedewald formula, whereby very-low-density lipoprotein cholesterol (VLDL-C) is estimated to be one-fifth the plasma triglyceride concentration. Ordinarily, this formula is applied only to plasma sampled from patients in the fasted state. To determine whether lipoprotein cholesterol measurements are altered substantially in plasma sampled from nonfasting subjects, we obtained postprandial blood samples from 22 healthy subjects (nine men, 13 women, ages 22-79 years) fed a fat-rich meal (1 g fat per kilogram body wt.). The plasma triglyceride concentration increased postprandially in all subjects (233 +/- 16% of baseline at 3 h). The mean cholesterol concentration in plasma was essentially unchanged. High-density lipoprotein cholesterol (HDL-C) was significantly decreased (94 +/- 2% at 3 h, P less than 0.001). VLDL-C and low-density lipoprotein cholesterol (LDL-C), estimated by the Friedewald formula, were compared with measurements obtained by modified Lipid Research Clinics (LRC) methodology. As measured by either method, VLDL-C increased and LDL-C decreased significantly after the fat-rich meal. These postprandial changes were significantly greater (P less than 0.01) when estimated by the Friedewald formula than by LRC methodology. We conclude that (a) lipoprotein cholesterol concentrations measured in the fed subject differ significantly from those measured in the fasted subject, and (b) plasma must be obtained after at least a 12-h fast if an individual's risk of coronary heart disease is to be accurately assessed.
Critical evaluation of the TDx Turbo Nephelometry System.
Authors: Renoe B W , Combs G L , Coffee E E , DeGrella R F 
Published: January 2020

Abstract
We critically evaluated the Nephelometry System (TDx Turbo) for the TDx Analyzer (Turbo), as currently used for immunoglobulins (IgA, IgG, and IgM) and transferrin assays. We describe hardware, software, reagent, and procedural changes made since the original publication (Clin Chem 1985;31:1474) and the mathematical treatment of data. The unit-dose format of the reagents allows for batch or panel testing of the analytes, with a throughput of 40 tests per hour. Measurements are made at pseudo-equilibrium, with sample-blank correction. The formulation of reagents and the assay scheme are such as to eliminate the need to check these assays for antigen excess. Assay sensitivities are 3% of the standard curve ranges. CVs are 8% for all assays. The system performance, when compared with rate nephelometry and radial immunodiffusion, yielded correlation coefficients of 0.97 or better for the analytes.
Calculation of low-density lipoprotein cholesterol with use of triglyceride/cholesterol ratios in lipoproteins compared with other calculation methods.
Authors: Rao A , Parker A H , el-Sheroni N A , Babelly M M 
Published: January 2020

Abstract
Low-density lipoprotein cholesterol was calculated with a formula that utilizes the triglyceride/cholesterol ratios in the different lipoprotein fractions, and also with different modifications of the Friedewald formula. Results of the former calculation correlated well with the ultracentrifugation-derived values and performed better than the other calculations at different lipid concentrations.
Carboxyhemoglobin as measured by gas chromatography and with the IL 282 and 482 CO-Oximeters.
Authors: Vreman H J , Mahoney J J , Van Kessel A L , Stevenson D K 
Published: January 2020

Abstract
We measured the concentration of carboxyhemoglobin (HbCO) in original and CO-tonometered blood samples from 53 intensive-care patients with IL 282 and IL 482 CO-Oximeters and by gas chromatography (GC), finding very strong correlations among the three methods for HbCO concentrations greater than 2.5%. For concentrations within the normal reference interval (less than or equal to 2.5%), however, the correlation between CO-Oximetry and GC is poor (r2 less than 0.26). The capillary mode of the IL 482 has a consistently lower correlation with any other method or mode. The correlations of measurements between the CO-Oximeters for total hemoglobin and oxyhemoglobin were excellent (r2 greater than or equal to 0.98). Correlations for methemoglobin were lower, owing to its low concentrations in the samples. We conclude that the IL 482 and the IL 282 are analytically equivalent for all analytes measured, but that both instruments differentiate poorly between HbCO values that fall within the reference interval.
Enzyme abnormalities of patients with acquired immunodeficiency syndrome.
Authors: Huang C M , Ruddel M , Elin R J 
Published: January 2020

Abstract
We determined the enzyme activities of glucose-6-phosphate isomerase, alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase in serum from 23 normal controls, 27 anti-HIV seropositive individuals confirmed by Western blot, and 53 patients with acquired immunodeficiency syndrome (AIDS). There is a significant difference for all four enzyme activities among controls, HIV seropositive individuals, and patients with AIDS, the enzyme activities showing a progressive increase as the disease progresses. Evidently these enzyme measurements may be adjunctive biochemical markers for progression of AIDS.
Heavy- and free light-chain myeloma associated with peripheral polyneuropathy.
Authors: Cotariu D , Kaufman S , Golik A , Scharf S , Zaidman J L 
Published: January 2020

Abstract
Peripheral polyneuropathy, a rare complication of multiple myeloma, is generally associated with heavy-chain M-proteins and, in very rare instances, with free light-chain myeloma proteins. Here we describe a case of multiple myeloma and polyneuropathy with both monoclonal IgG and free lambda light chains in the blood. The patient also had free lambda light chains in the cerebrospinal fluid and urine.
Bioassay of thyroid-stimulating immunoglobulin in cryopreserved human thyroid cells: optimization and clinical evaluation.
Authors: Kraiem Z , Glaser B , Pauker J , Sadeh O , Sheinfeld M 
Published: January 2020

Abstract
We have explored the method of Rapoport et al. (J Clin Endocrinol Metab 1984;58:332-8) for the bioassay of thyroid-stimulating immunoglobulin (TSI) in cultured human thyroid cells, to optimize the assay and to evaluate its utility in clinical diagnosis and management of patients with autoimmune thyroid disease. Here we describe the procedure ultimately adopted, its major properties, and the results it has yielded in various clinical states. Clinical sensitivity of the assay was established by demonstrating TSI activity in all of 60 cases of active Graves' disease. We observed in these patients a nonlinear correlation between concentrations of TSI and of triiodothyronine, as well as between TSI concentration and the clinical severity of the thyrotoxicosis. Specificity of the assay was demonstrated by finding no TSI bioactivity in 13 patients with toxic adenoma, five with cold nodule, and 18 of 19 with nontoxic goiter. Remission of Graves' disease in 25 patients was invariably accompanied by undetectable concentrations of TSI; evidently this assay may be useful in identifying patients who are likely to go into remission. TSI activity was present in eight of 11 patients with euthyroid ophthalmopathy (unilateral and bilateral) associated with a normal response to the thyrotropin-releasing hormone test and absence of increased titers of antithyroid antibodies, suggesting that this assay may provide a powerful tool in the clinical diagnosis of this disorder.
Comparing different statistical methods for evaluating diagnostic effectiveness of clinical tests: respiratory distress syndrome as a model.
Authors: Amenta J S , Brocher S C , Serenko-Aber A L 
Published: January 2020

Abstract
Phospholipids in specimens of amniotic fluid from 346 patients were quantified and the results evaluated in light of the clinical outcome. Fifty-eight neonates had respiratory distress syndrome. We used this data base to compare different statistical methods for evaluating test effectiveness and diagnostic discrimination. Dichotomizing quantitative tests into binary tests with arbitrary cutoff values was inadequate for comparing test effectiveness. Subgrouping the data into deciles and calculating the incidence of respiratory distress syndrome for each decile avoided the problems of the preceding approach and was easy to calculate and comprehend; however, this method lacked statistical power. Relative operating characteristic curves yielded more statistical power, but results were more difficult to calculate and were not intuitively obvious to most workers in the laboratory. A modified cumulative frequency plot, combining elements of both decile subgrouping and relative operating characteristic curves, was easily calculated and intuitively obvious. These plots, like relative operating characteristic curves, provided an index for quantifying test effectiveness. When used in combination with standard cumulative frequency curves, they also provided direct diagnostic information on disease probability for any value of the clinical assay.
Acute intestinal infarction or obstruction: search for better laboratory tests in an animal model.
Authors: Kazmierczak S C , Lott J A , Caldwell J H 
Published: January 2020

Abstract
Mesenteric vascular occlusion and intestinal obstruction are difficult-to-diagnose medical emergencies. We evaluated a large panel of biochemical markers as diagnostic and prognostic indicators in a rat model of intestinal infarction and partial, complete, and strangulated intestinal obstruction. After intestinal infarction and obstruction, laboratory data are distinctly abnormal. Serum urea nitrogen dramatically increased in all groups, but most rapidly in the groups with infarction and strangulated obstruction. Inorganic phosphorus proved to be a sensitive indicator of infarction, but less so for any form of obstruction. While all members in the infarct group demonstrated significant increases in the aminotransferases, creatine kinase, and alkaline phosphatase, such increases in the groups with obstruction were less pronounced. Serum maltase assays revealed decreasing activities in all members of the groups with complete and strangulated obstruction, but in only 17% of the rats with partial obstruction. Serum maltase activity increased from abnormally low values after surgery to abnormally high values in the six animals that recovered from partial intestinal obstruction. The proportion of hexosaminidase A (of total beta-N-acetylhexosaminidase, EC 3.2.1.30) was generally abnormal in rats with complete and strangulated obstruction.
Evaluation of a single-color-reading method for determining fructosamine.
Authors: Rosenthal M A , Olenick L J 
Published: January 2020

Abstract
A commercial kit for determining fructosamine was evaluated. The reference interval (determined from data on 183 nondiabetic subjects) was 1.67 to 2.85 (mean 2.17) mmol/L. Serum and plasma (EDTA- or heparin-anticoagulated) gave equivalent results; plasma treated with fluoride/oxalate gave slightly lower values. The between-run CV was less than 4%. Fructosamine values were similar by the present method and the kinetic method. The standard curve was linear in the range of 1.3 to 8.5 mmol/L. None of several constituents of blood that we tested appreciably interfered. Fructosamine values were increased in some lipemic samples from non-diabetics, and were significantly correlated with glycated hemoglobin as measured by affinity chromatography. This kit evidently is a suitable alternative to the kinetic method for determining fructosamine.
Clinical application of serum bilirubin fractionation by simplified liquid chromatography.
Authors: Adachi Y , Inufusa H , Yamashita M , Kambe A , Yamazaki K , Sawada Y , Yamamoto T 
Published: January 2020

Abstract
Serum bilirubin was fractionated by a new reversed-phase "high-performance" liquid-chromatographic (HPLC) procedure, on Micronex RP-30, a polyacryl ester. The five fractions were: delta (delta-bilirubin, B delta), gamma (bilirubin diglucuronide, BDG), beta (bilirubin monoglucuronide, BMG), beta' [(Z,E)- and (or) (E,Z)-bilirubin IX alpha], and alpha [(Z,Z)-bilirubin IX alpha]. We found close correlation with results of the modified HPLC fractionation of Lauff et al. (J Chromatogr 1981;226:391-402), except for the beta' fraction, which was eluted after beta. The Micronex HPLC involves a simple pretreatment of serum samples, in contrast with the complex preparation described by Lauff et al., and is convenient for routine use in the clinical evaluation of hyperbilirubinemia. We could quantify B delta, BDG, BMG, and unconjugated bilirubin even in sera with normal values for total-bilirubin concentrations. Photoderivatives of bilirubin such as the beta' fraction could be separated and quantified by the same procedure, making the method feasible for pediatric research.
Circulating concentrations of immunoreactive peptide 7B2 in certain pathophysiological conditions, and response to oral glucose load.
Authors: Suzuki H , Kobori H , Ohtake R , Hashigami Y , Suzuki Y , Shimoda S I , Bloom S R 
Published: January 2020

Abstract
A peptide, 7B2, originally isolated from pituitary, is present in endocrine tumors, with high concentrations in pancreatic islet tumors. Plasma from most of these patients showed very high immunoreactivity to 7B2 (IR-7B2). To assess whether or not there is any alteration in circulating 7B2 concentrations due to age, sex, etc., we measured concentrations in plasma in 96 fasting healthy subjects, ages three months to 91 years; in patients with various other conditions, including pregnancy; and in cord blood. The response of circulating IR-7B2 to oral glucose was also evaluated. We found particularly high IR-7B2 concentrations in cord blood. Postnatally the concentrations were lower and decreased gradually with age to values for adults [15.6 (SE 2.9) pmol/L], increasing again significantly (P less than 0.01) in persons older than 70 years [37.1 (SE 32) pmol/L]. There was no significant sex-related difference in values for plasma. For the pathological conditions studied, we observed significantly supranormal values in patients with chronic renal failure [175.1 (SE 35.9) pmol/L]. Some of the pregnant patients in their third trimester also showed high values. A small but significant increase in plasma IR-7B2 was observed after a glucose load, both in control subjects and diabetics. Perhaps the kidney plays a major role in 7B2 degradation.
Evaluation of determination of uric acid in serum and whole blood with the Reflotron.
Authors: Cattozzo G , Franzini C , Hubbuch A , Tritschler W 
Published: January 2020

Abstract
The performance of the Reflotron system (Boehringer Mannheim) for the determination of urate in whole blood and serum was evaluated. Within-run and day-to-day imprecision of the system were comparable with those for a solution-chemistry enzymatic method (overall CVs in the range 2.2-2.5%). Results for 100 individual specimens with urate concentrations ranging from 16 to 134 mg/L agreed well with the comparison method, both for serum and whole blood. We saw no significant interference from lipemia or hemoglobin. Bilirubin interfered at concentrations greater than 100 mg/L. Hematocrit variation between 25% and 55% did not affect results for whole blood; variation of the applied sample volume from 28 microL to 35 microL (stated sample volume requirement: 30 microL) did not significantly influence the measured value. We consider results produced by the system to be of the same analytical quality as those obtained by the more conventional solution-chemistry methods that are currently available.
Improved procedure for measuring gamma-glutamyltransferase isoenzymes in serum.
Authors: Sacchetti L , Castaldo G , Fortunato G , Salvatore F 
Published: January 2020

Abstract
In this electrophoretic procedure for measuring isoenzymes of gamma-glutamyltransferase, patterns obtained are highly reproducible and the analytical imprecision (CV) ranges from 1.10% to 6.17%. A cellulose acetate support is used, at 220 V for 40 min. Sharply resolved isoenzyme bands were made visible by fluorescence scattered light, formed by use of a coumarin derivative as donor substrate. Two bands were observed for sera from normal subjects; four bands were variably present in sera from patients with different hepatobiliary diseases. Detection of the latter was satisfactory, down to a total activity in serum of 8-10 U/L. Three of the pathological bands were associated with low- and (or) very-low-density lipoproteins, whereas a major fraction of one of the normal bands in cirrhotic sera precipitated with high-density lipoprotein. The bands in normal sera, and one of the abnormal bands, did not.
Analytical and technical aspects of testing for drug abuse: confirmatory procedures.
Authors: Peat M A 
Published: January 2020

Abstract
Many laboratories are now performing urine drug testing for employers, governmental agencies, and other institutions. It is now recognized that presumptive positive screening results have to be confirmed by an analytical procedure based on a different chemical technique with greater than or equal sensitivity to the screening test. Thin-layer chromatography has been widely used for this; however, it is relatively insensitive for certain drugs, and it cannot satisfy the accuracy and precision requirements needed to determine threshold concentrations reliably. Gas chromatography-mass spectrometry is able to satisfy these threshold requirements and has become the method of choice for confirming initial immunoassay results.
Quinidine-induced inhibition of leukocyte esterases.
Authors: Markovic O T , Young D S , Markovic N S 
Published: January 2020

Abstract
We have demonstrated the feasibility of a system based on image processing to measure enzyme activity inside morphologically classified individual cells. When used in this system, quinidine inhibited naphthol AS-D chloroacetate esterase in polymorphonuclear neutrophils and alpha-naphthyl acetate esterase and alpha-naphthyl butyrate esterase in monocytes. These effects were dependent on the duration of exposure and on drug concentration. Dose-effect relationships were established and the concentration at which 50% inhibition (ID-50) occurred was used as a reference point to compare the toxicity of different compounds. Chloroquine, primaquine, and quinine (which, like quinidine, possess a quinoline ring) also affected the esterases, but had no effect on several other enzymes. Neostigmine inhibited the esterases we studied but only at a very high concentration. Various chemicals inhibited the enzymes within the cells, as has been demonstrated for the enzymes in plasma.