bluuebunny/crossref_metadata_2025 huggingface dataset:
Progesterone receptor: stability studies and correlation between steroid binding assay and enzyme immunoassay.
Authors: Wu J T , Wilson L W
Published: January 2020

We evaluated and compared Abbott Laboratories' newly developed enzyme immunoassay (EIA) for measuring progesterone receptors (PgR) with that of DuPont's steroid-binding assay (SBA). We also used both methods to study the stability of PgR under various conditions. THere were excellent correlations for all 59 cytosols compared (r = 0.94) and for the 44 cytosols containing PgR greater than 10 fmol per milligram of protein (r = 0.93), but the correlation for cytosols containing less than 10 fmol of PgR per milligram was poor. We found PgR to be more stable as assayed by EIA than by SBA. The biological half-lives of PgR at 30, 4, and -60 degrees C were approximately 3 h, 6 days, and 19 days, respectively. The effect of molybdate on PgR is complex. Its presence during tissue homogenization leads to analytical recovery of more PgR and may stabilize PgR during storage. Its presence during enzyme immunoassay is less critical. Unlike estrogen receptor, PgR is not protected by its ligand, R5020.
Albumin excretion rate, albumin concentration, and albumin/creatinine ratio compared for screening diabetics for slight albuminuria.
Authors: Hutchison A S , O'Reilly D S , MacCuish A C
Published: January 2020

Slight albuminuria, an overnight albumin excretion rate (AER) greater than 30 micrograms/min in an "Albustix"-negative sample, predicts development of diabetic nephropathy. This study compares the AERs for 261 timed overnight urine collections with the albumin concentrations and albumin/creatinine ratios for the same specimens (equivalent to first morning specimens). Thirty-one specimens (11.9%) had AERs greater than 30 micrograms/min. Use of an albumin/creatinine ratio greater than 3.0 mg/mmol to predict an AER greater than 30 micrograms/min gave a sensitivity of 96.8%, a specificity of 93.9%, and a predictive value of 68.2%, with a correlation coefficient of 0.921. Use of an albumin concentration greater than 17 mg/L gave a sensitivity of 96.8%, a specificity of 90.9%, a predictive value of 58.8%, and a slightly poorer correlation (r = 0.904). Evidently either method is acceptable as an initial screening procedure, but determination of albumin concentration alone would be preferable because of lesser cost.
23Na nuclear magnetic resonance study of Na+-K+ pump inhibition by a fraction from uremic toxins.
Authors: Gallice P , Monti J P , Baz M , Murisasco A , Crevat A
Published: January 2020

An in vitro inhibitor of Na+/K+-transporting ATPase (EC 3.6.1.37) was isolated from uremic plasma and normal urine by liquid chromatography. A 23Na nuclear magnetic resonance study involving living erythrocytes showed that this inhibitor causes impairment of the Na+-K+ pump of intact erythrocytes. This finding may explain the high intra-erythrocytic sodium concentration in those uremic patients exhibiting a high concentration of this inhibitor. The presence of this same inhibitor in normal urine suggests that it may play a physiological role.
Changes in magnesium, zinc, calcium, potassium, cholesterol, and creatine kinase concentrations in patients from pre-infarction syndrome to fatal myocardial infarction.
Authors: Speich M , Gelot S , Arnaud P , Nicolas G
Published: January 2020

We measured changes in concentrations of magnesium, zinc, calcium, potassium, cholesterol [total and high-density lipoproteins (HDL)], total creatine kinase (CK), and CK isoenzyme-MB in plasma (PI) and/or erythrocytes (Erc) from apparently healthy subjects and from patients with either pre-infarction syndrome (PIS) or myocardial infarction (MI) with a favorable (MI1) or fatal (MI2) outcome, to assess the relationship of these changes to the increasing severity of ischemic disease. Significant sex-related differences led us to study men and women separately. In MI1 and MI2 patients, concentrations of Mg in PI and Erc were increased as a function of time since the infarct, confirming the cardiac Mg leaves the heart and enters the circulatory compartment. Compared with concentrations in MI2 patients, Zn concentrations in PI were lower in MI2 patients in the days before death. Significant negative correlations between Zn in PI in MI1 men or Zn in Erc in MI2 men and CK or CK isoenzyme MB suggest that circulating Zn is taken up by non-necrotic myocardial tissue as part of the repair process. MI2 patients had gradually decreasing Ca concentrations in PI even more marked than those observed in PIS and MI1 patients. We also noted a marked decrease in total and HDL cholesterol concentrations in both MI2 men and MI2 women shortly before death.
Enzyme immunosorbent assay of prolactin with penicillinase as label.
Authors: Shrivastav T G , Pandey P K , Kumari G L
Published: January 2020

This competitive, rapid, and sensitive enzyme immunosorbent assay for measuring human prolactin in plasma involves penicillinase (EC 3.5.2.6) as label. Microtiter plate wells coated with goat anti-rabbit gamma globulin are filled with antibody to prolactin and plasma sample or reference prolactin and incubated with penicillinase-labeled prolactin for 1 h at 37 degrees C. The enzyme activity of the bound complex is then measured. The assay is as sensitive as radioimmunoassay, the detection limit being 2.5 ng of prolactin per milliliter of plasma. The plasma prolactin values obtained by enzyme immunoassay correlated well with those determined by radioimmunoassay: r = 0.98, slope = 1.00, intercept = 1.11 ng/mL (n = 53).
A highly specific radioreceptor assay for the active circulating form of atrial natriuretic factor in human plasma.
Authors: Ong H , De Léan A , Gagnon C
Published: January 2020

This highly sensitive radioreceptor assay (RRA) for the active circulating form of atrial natriuretic factor (ANF), fragment 99-126, in human plasma requires 125I-labeled ANF, bovine zona-glomerulosa membrane receptors, and amiloride HCl. The amiloride elicits an increase in the binding affinity of ANF to its receptors. ANF is extracted from human plasma with "Sep-Pak" cyano cartridges. After a 90-min incubation at 25 degrees C, bound and free fractions are separated by filtration. The ANF concentration that inhibits receptor binding of the radioligand by 50% is 12.4 fmol of unlabeled ANF per tube. The minimum detectable concentration is 0.2 fmol per tube. Using ANF-supplemented plasma samples, there was a good correlation (r = 0.99) between ANF concentrations found and those expected. Only the active circulating form of ANF fully cross-reacts in this assay, which confirms its high selectivity. Results correlated strongly (r = 0.93) for clinical samples tested by RRA and RIA.
A re-examination of the stability of retinol in blood and serum, and effects of a standardized meal.
Authors: Barreto-Lins M H , Campos F A , Azevedo M C , Flores H
Published: January 2020

We examined the stability of retinol in blood and serum samples, kept in the dark, under different handling procedures. Samples not protected from contact with air oxygen were highly unstable, even when kept at ice temperature. Samples collected under anaerobic conditions, with Vacutainer Tubes, or treated with nitrogen after collection to displace the air from the tubes were stable during the usual interval between collection and freezing or analysis in biochemical surveys. Ingestion of a moderate amount of vitamin. A significantly increased serum retinol concentrations in normal volunteers, showing the importance that survey samples be preprandial.
Significance of low concentrations of creatinine in serum from hospital patients.
Authors: Hagemann P , Kahn S N
Published: January 2020

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Excretion of digoxin-like immunoreactivity in urine of normal subjects: correlations with excretion of creatinine and electrolytes.
Authors: Clerico A , Giampietro O , Gregori G , Del Chicca M G , Bertoli S , Miccoli R , Navalesi R
Published: January 2020

To verify whether there is a variation in the 24-h urinary excretion of digoxin-like immunoreactivity (DLIS) in humans, we studied 18 normal adults, who collected their urines for 24-h in several portions. We then measured DLIS (by means of a sensitive RIA method), creatinine, sodium, and potassium concentrations in the urine samples. The mean urinary excretion rate for DLIS in the complete 24-h collection was 84.8 (SD 31.3) pg/min. The mean DLIS urinary excretion rate calculated for overnight collections was significantly lower than those of afternoon collections (P less than 0.01) and the 24-h collection (P less than 0.05). Significant positive correlations were found between urinary DLIS and excretion rates for creatinine (r = 0.347, P = 0.0016), Na+ (r = 0.232, P = 0.038), and K+ (r = 0.323, P = 0.003), respectively. Our data suggest that urinary excretion of DLIS is higher during "active" hours of the day, especially in the afternoon, than at rest, during the night.
Melanogenuria: laboratory evaluation of the qualitative Thormählen and ferric chloride tests and their clinical utility.
Authors: Scott R E , Ward V L , Grinstead G F , Stevens B S , Wilson D M
Published: January 2020

Malignant melanoma, a disease that is increasing in occurrence and medical concern, is characterized by the excretion of melanogens. Two qualitative tests are recommended for melanogen detection, the Thormählen test and the ferric chloride test. We evaluated the laboratory and clinical performance of these tests by subsequently re-evaluating 201 urine samples that had been submitted for routine melanogen analysis. We used (a) Thormählen, (b) ferric chloride, (c) small-scale thin-layer chromatography, and (d) spectrophotometry. Nearly 30% of Thormählen test results were equivocal. The ferric chloride test was of no value in itself or in categorizing equivocal Thormählen results as positive or negative. The small-scale chromatography was irreproducible. Prompt scanning of the Thormählen reaction product was helpful in classifying equivocal results. History review of 121 histopathologically diagnosed melanoma patients indicated that these qualitative assays were of no clinical value in the diagnosis or monitoring of melanoma patients.
Intra-individual variation of thyroxin, triiodothyronine, and thyrotropin in treated hypothyroid patients: implications for monitoring replacement therapy.
Authors: Browning M C , Bennet W M , Kirkaldy A J , Jung R T
Published: January 2020

We measured total thyroxin (TT4), free thyroxin (FT4), total triiodothyronine (TT3), free triiodothyronine (FT3), and thyrotropin (TSH) in serum sampled before and 1, 2, 4, 6, and 8 h after administration of prescribed doses of thyroxin to 12 patients with proven primary hypothyroidism. At 2, 4, and 6 h post-dose, the mean values for TT4 and FT4 and also that at 8 h for FT4 significantly (P less than 0.05) exceeded the corresponding pre-dose values. No significant changes were found for TT3, FT3, or TSH. The mean intra-individual CVs over the study period were TT4 4.9%, FT4 5.7%, TT3 8.7%, FT3 8.7%, and TSH 20.2%. Individual subjects showed small but predictable changes in TT4 and FT4. Changes in TT3 and FT3 were greater but random. Fluctuations in TSH were greatest, but in all subjects with detectable concentrations the variations were of similar magnitude. We conclude that strict adherence to timing of specimen collection in relation to dosage is probably unnecessary.
The changing epidemiology of depression.
Authors: Klerman G L , Weissman M M
Published: January 2020

At the clinical level, we have seen the emergence of a subspecialty of affective disorders within psychiatry. Mood clinics, depression units, and affective disorders centers are appearing in many academic and clinical settings, where clinical skill and knowledge can be concentrated and new research furthered. By using structured interviews and the newer diagnostic systems, systematic evaluation of patients has contributed to improved care. Greater skill in psychopharmacology and in specialized psychotherapeutic techniques has resulted in reduction of hospitalization and rates for depression, shortened duration of illness, and, in some instances, reports of reduction in suicide attempts and suicide deaths.
Reliability of antidepressant assays: a reference laboratory perspective on antidepressant monitoring.
Authors: Labrosse K R , McCoy H G
Published: January 2020

Chromatography (gas and liquid) and immunoassays are used for monitoring the commonly prescribed tricyclic antidepressants. Many commercially available immunoassays are known to cross react with structurally similar compounds. Chromatographic methods make it possible simultaneously to resolve and quantify amitriptyline, nortriptyline, imipramine, desipramine, trimipramine, doxepin, desmethyldoxepin, protriptyline, and maprotiline-and potentially crossreactive compounds can be separated from the tricyclics. Immunoassays may have a valuable role in initial toxicological screening for the presence of a tricyclic-like compound, and they also may be helpful in a laboratory dedicated to a well-controlled patient group. However, 10% of our specimens contain more or different antidepressants than we are requested to analyze for. With our analysis, we are able to report which antidepressants are present, and in what concentrations. Further, in the case of a potential overdose of tricyclic, the primary purpose for early toxicological analysis to anticipate subsequent clinical complications. Therefore, even in the case of toxicological analysis, it is important to know exactly what tricyclic antidepressant is present rather than just the semiquantitative presence of one or more structurally related compounds, because these various compounds differ markedly in their potential for adverse effects. There are too many potential, and possibly yet unknown, interactions for a reference laboratory routinely to rely on immunoassays for therapeutic drug monitoring or toxicological identification of antidepressants.
Pharmacokinetic factors affecting antidepressant drug clearance and clinical effect: evaluation of doxepin and imipramine--new data and review.
Authors: Ereshefsky L , Tran-Johnson T , Davis C M , LeRoy A
Published: January 2020

The selection of a starting dose for an antidepressant, and subsequent clinical titration to an appropriate therapeutic dosage, should be based on pharmacokinetic and pharmacodynamic principles. In the past decade, therapeutic monitoring of antidepressant drugs and use of pharmacokinetic principles have been shown to be an improvement over the dose-response approach. Endogenous (e.g., genetic metabolic phenotype, hepatic blood flow, and protein binding) and exogenous factors (e.g., smoking, dietary habits, concurrent medications) are capable of influencing physiological and pharmacokinetic variables in patients, accounting for the marked interindividual differences in the clearance rates of cyclic antidepressants. Interpatient variability for steady-state concentrations in plasma (Cpss) greater than 20-fold are observed at a fixed dose of imipramine (r2 = 0.525, df = 346, t = 19.541, P less than 0.0001) or doxepin (r2 = 0.506, df = 128, t = 11.403, P less than 0.0001). Analysis of doxepin in plasma vs estimated in oral clearance for 61 patients demonstrates a significant decline in oral clearance as a function of Cpss. At doses approaching the upper range recommended for the treatment of depression, Cpss appear to approach, in at least a few individuals, the maximum metabolic capacity of the patient (Vmax), leading to greater-than-expected increases in concentrations for a given dosage increment. Significant alterations in oral clearance are observed when medications are administered concomitantly. A greater-than-threefold difference in mean oral doxepin clearance rates is observed between two groups of patients receiving additional medications that are either inducers or inhibitors (P less than 0.0001, df = 32, t = 6.687). Pharmacokinetic principles defining and explaining the determinants of oral clearance can provide the clinician with a greater insight into the reasons for therapeutic failure and toxicity.
Quantification of hemoglobins S, C, and F by a magnetic affinity immunoassay.
Authors: Moscoso H , Kiefer C R , Kutlar A , Garver F A
Published: January 2020

This magnetic affinity immunoassay (MAIA) quantifies hemoglobins (Hb) S, C, and F in hemolysates from adults or newborns. Monospecific antisera to the hemoglobins are covalently conjugated to magnetic beads and reacted with the corresponding 125I-labeled hemoglobin. After centrifugation to separate the free and antibody-bound 125I-labeled hemoglobin, the amount of radioactive hemoglobin in the pellet is measured. To determine the concentration of the Hb under study, the percent inhibition of the reaction is quantified. The standard curve is established by adding known quantities of unlabeled hemoglobin before adding 125I-labeled hemoglobin. The amount of Hb S, Hb C, or Hb F present in hemolysates is determined by measuring the percentage of inhibition and extrapolating the concentration from the standard curve. Results agree well with values for Hb S and Hb C obtained by "high-performance" liquid chromatography and RIA and for Hb F as measured by alkali denaturation and RIA. This assay can be completed in 1 h and is more sensitive than enzyme immunoassay or RIA: we can detect proportions of Hb S and Hb C as low as 1% of total Hb, and Hb F as low as 0.05%.
Incidence and source of hyperamylasemia after cardiac surgery.
Authors: Kazmierczak S C , Van Lente F
Published: January 2020

We investigated the incidence and possible mechanisms of postoperative hyperamylasemia in 101 patients after cardiac surgery. Amylase (EC 3.2.1.1) activities in serum were increased in 36% of patients after bypass surgery, 59% of patients after valve replacement, and in 69% of patients after combined bypass and valve replacement. Lipase (EC 3.1.1.3) activity was increased in 30% of all patients. We found enzymatic evidence for pancreatitis in six patients. Thirty-six patients showed increased salivary (S-type) amylase activity, with a positive correlation (r = 0.55, P less than 0.001) between the severity of pleural effusions and the peak S-type amylase activity. Hyperamylasemia after cardiac surgery is apparently often related to absorption of S-type amylase from pleural fluid and (or) from aspirated salivary secretions. Monitoring patients for postsurgical pancreatitis necessitates assay of amylase isoenzymes to distinguish abnormalities resulting in release of pancreatic (P-type) amylase from those involving release of S-type amylase.
Solid-phase radioimmunoassay of human complement fragment C5a.
Authors: Chang S , Leo-Mensah A , Campbell J , Stastny M , Patrick R A
Published: January 2020

In this competitive RIA for determining concentrations of human C5a in biological fluids and in buffers, labeled C5a and sample are allowed to compete for binding to a limited amount of goat antibody to human C5a in solution. Free and bound tracer are then separated by a second antibody (rabbit anti-goat IgG) immobilized on paramagnetic particles. Total incubation time for this assay is 70 min. Sensitivity, precision, and analytical recovery of this assay compare well with those of a reference method.
Heterogeneity of lipoprotein Lp(a) and apolipoprotein(a).
Authors: Grinstead G F , Ellefson R D
Published: January 2020

We have purified Lp(a) lipoproteins from sera of four subjects by ultracentrifugation, selective precipitation, and chromatofocusing. Each subject had two forms of serum Lp(a) that were separable by chromatofocusing. We purified apolipoprotein (a) [apo(a)] from the eight isolated Lp(a)s and obtained only one form of apo(a) from each subject. The four apo(a)s seen on sodium dodecyl sulfate-polyacrylamide gel electrophoresis had different apparent molecular masses, ranging from 275 to 440 kDa. Chemical deglycosylation of the smallest apo(a) yielded a 235 kDa protein, which may be a core protein structure common to all apo(a)s. We conclude that there are many forms of serum Lp(a) and apo(a). The heterogeneity of serum Lp(a) particles can be ascribed in part to differences in size of apo(a), but other factors must account for the existence within a single patient of different Lp(a)s that contain apparently identical apo(a). One must consider the heterogeneity of Lp(a) when designing assays for this lipoprotein.
Ratios for very-long-chain fatty acids in plasma of subjects with peroxisomal disorders, as determined by HPLC and validated by gas chromatography-mass spectrometry.
Authors: Hall N A , Lynes G W , Hjelm N M
Published: January 2020

We describe an HPLC method for measurement of ratios of concentrations of very-long-chain fatty acids (VLCFA) in plasma. The method, which involves ultraviolet detection of p-bromophenacyl derivatives of fatty acids, is validated by comparison with a gas chromatographic-mass spectrometric (GC-MS) method. The correlation between the ratios of 24-carbon fatty acids to 22-carbon fatty acids (C24/C22) estimated by the two methods was close (r = 0.976) as was the correlation for the C26/C22 ratios (r = 0.947). Increased VLCFA ratios could be demonstrated by either technique in patients with adrenoleukodystrophy, Zellweger syndrome, and infantile Refsum's disease. The HPLC method also measures phytanate concentrations in plasma. Control VLCFA ratios (for subjects without peroxisomal disorders) obtained by the two methods agree well with those reported by Moser et al. (Ann Neurol 1984; 16:628-41). For subjects younger than one year, ratios for C24/C22 and C26/C22 fatty acids were significantly greater than in older subjects.
Creatine kinase MM isoforms in serum after cardiac surgery.
Authors: Keshgegian A A , Bhagat P K , Lease J A , Balocchi J
Published: January 2020

We evaluated creatine kinase (CK; EC 2.7.3.2) MM3:MM1 isoform ratios in the serum of cardiac patients immediately after cardiac surgery for the diagnosis of perioperative myocardial injury. The mean ratio was 4.8 (range, 1.4-10.7) in 22 patients who had postoperative myocardial complications and 4.6 (1.3-9.6) in 66 patients who did not. By the first postoperative day the ratio had decreased substantially in both groups of patients. The isoform ratio did not correlate with the concentration of total CK, CK-MB, total lactate dehydrogenase (LD), or the incidence of LD1:LD2 or LD5:LD2 ratio reversal. Of these measurements, CK-MB and LD concentrations differed most between the groups of patients; parallel testing of CK-MB and LD showed an optimized sensitivity and specificity of 77% and 87%, respectively. We conclude that analysis for CK-MM isoforms does not add information in the period immediately after cardiac surgery; concentrations of CK-MB and LD correlate with myocardial injury, but the sensitivity and specificity of these measurements may not be high enough for clinical utility.
Confirmation of a false-positive result in CA 125 immunoradiometric assay caused by human anti-idiotypic immunoglobulin.
Authors: Klug T L , Green P J , Zurawski V R , Davis H M
Published: January 2020

An immunoradiometric assay (IRMA) involving a monoclonal antibody (MAb OC125) to an ovarian carcinoma-associated antigenic determinant (CA 125) has been tested as one component in a strategy for early detection of epithelial ovarian cancer. We characterized one confirmed "false-positive" sample by murine antibody blocking studies, Western blotting, immunoaffinity, size-exclusion chromatography, and reactivity with polyclonal rabbit antisera to CA 125 antigen. The positive response of this serum in the CA 125 IRMA was due to a human IgM. The discrepant IgM was isolated from the serum by successive immunoaffinity steps with nonspecific murine MAb, MAb OC125, and goat antibodies to human IgM Fc. Purified IgM inhibited the binding of MAb OC125 to CA 125. Furthermore, rabbit antisera to CA 125 antigen competitively inhibited the binding of MAb OC125 to both CA 125 and the discrepant IgM. The discrepant activity thus appears to reflect binding of this human IgM to a idiotope of MAb OC125. Radioiodination of MAb OC125 by a different technique eliminated the discrepant activity and decreased the incidence of CA 125 positivity in an at-risk population of apparently healthy women, increasing the specificity of the IRMA to 99.8% in this group.