bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of antidepressants by liquid chromatography: a review of current methodology.
Authors: Wong S H 
Published: January 2020

Abstract
Antidepressant measurement by liquid chromatography (LC) has enhanced the therapy of patients who are being treated with some of the first generation tricyclic antidepressants; the merits of routinely monitoring the other antidepressants await further study. Currently, the role of LC is changing from dominant to complementary as a result of the recent availability of monoclonal antibody immunoassays with increased specificity. For successful application of LC, considerations would include designing the sampling protocol and matching assay that together are uniquely suitable for a particular laboratory. The assay should be simple, the sample preparation manual (liquid-liquid, solid-phase extraction columns), semi-automated, or automated. Normal- or reversed-phase columns with functionalities such as C-18, CN, C-8, and phenyl are used. Other useful LC variables include particle size, capping, ion-pairing, and recycling. This survey of LC methods includes the first and second generations, and new antidepressants such as alprazolam, amoxapine, bupropion, maprotiline, trazodone, and selected metabolites. Potential chromatographic interference by (e.g.) benzodiazepines and neuroleptics is addressed, followed by proposed guidelines for their resolution. Future developments are discussed.
Effect of blood collection and processing on radioimmunoassay results for apolipoprotein A-I in plasma.
Authors: Brown S A , Rhodes C E , Dunn K , Gotto A M , Patsch W 
Published: January 2020

Abstract
We studied the effects of different procedures of blood collection and processing on quantification of apolipoprotein A-I (apoA-I) by radioimmunoassay. ApoA-II and apolipoproteins of low- and very-low-density lipoproteins did not cross react in the assay. Analytical recovery of apoA-I at different doses was complete. ApoA-I concentration in pooled human plasma was stable for as long as a year stored at -70 degrees C. Inter- and intra-assay CVs averaged 7% and 5%, respectively. We collected blood from 20 subjects into tubes containing EDTA alone or EDTA with antiproteolytic agents, then separated the plasma either immediately or after 3 h at 4 degrees C. We tested various formulations of antibacterial, antiproteolytic, and anti-oxidant agents added to plasma, measuring apoA-I concentrations either within 24 h of blood collection or after storage of plasma for 6 weeks at -70 degrees C. No significant difference in the concentrations of apoA-I was found in these specimens, regardless of the conditions studied. We conclude that addition of protective agents other than EDTA is not necessary during blood collection or specimen processing for reliable quantification of apoA-I in fresh or frozen human plasma.
Urinary alanine aminopeptidase assay improved as result of multivariate response-surface analysis.
Authors: Flandrois C , Lahet C , Feldmann D , Gabastou J M , Gonnon A , Maire I 
Published: January 2020

Abstract
Optimization of determination of alanine aminopeptidase in urine by univariate study led to a method involving pretreatment of urine with Sephadex G50. Re-examination of the optimization by multivariate study led us to recommend higher optimal concentrations: 5.8 mmol/L for the substrate and 300 mmol/L for the Tris buffer. Under these new conditions, pretreatment of urine was no longer necessary and the assay could be completely automated.
Excretion of endogenous digoxin-like immunoreactive factors in human urine is a function of urine flow rate.
Authors: Siegfried B A , Valdes R 
Published: January 2020

Abstract
We studied the effect of varying water and salt intake on the renal excretion of endogenous digoxin-like immunoreactive factors (DLIF). DLIF were measured in human urine and serum by competitive displacement of 125I-labeled digoxin from anti-digoxin antibodies. Diuresis was selectively induced in normal healthy humans by acute water ingestion, and natriuresis was preferentially induced by acute saline ingestion. We found the amount of endogenous immunoreactivity excreted in urine to be correlated with urine flow rate but not with urinary sodium excretion. Urinary excretion of DLIF, normalized to creatinine, was 3.6-fold greater at a urine flow rate of 5.5 mL/min than at 0.5 mL/min. On the other hand, saline intake increased urine flow rate 1.9-fold and increased sodium excretion threefold, but did not affect urinary excretion of DLIF. Fractional excretion of DLIF was linearly related to fractional excretion of water. This study demonstrates that normalization of DLIF values to urinary creatinine does not make DLIF excretion independent of urine flow rate and underscores the need for information on urine flow rate when DLIF measurements in urine are being interpreted.
A user evaluation of four Kodak Ektachem slide assays.
Authors: Bissell M G , Hussain S , Sanghavi P , Ward E , Shaw S T 
Published: January 2020

Abstract
Evaluations of magnesium, theophylline, creatinine, and creatine kinase isoenzyme MB assays by the Kodak Ektachem multilayer-film technique are reported.
Liquid-chromatographic determination of free and total 3,4-dihydroxyphenylglycol and 3-methoxy-4-hydroxyphenylglycol in urine.
Authors: Julien C , Rodriguez C , Sacquet J , Cuisinaud G , Sassard J 
Published: January 2020

Abstract
We describe the conjoint measurement in urine of the alcoholic catecholamine metabolites 3,4-dihydroxyphenylglycol (DHPG) and 3-methoxy-4-hydroxyphenylglycol (MHPG). The method involves extraction with ethyl acetate and back-extraction into acetic acid (MHPG), followed by adsorption onto alumina (DHPG). The separation is performed by reversed-phase liquid chromatography with column switching and amperometric detection. Total (free plus conjugated) compounds are determined after a 24-h enzymatic hydrolysis. Twelve-hour excretion values for normal and hypertensive subjects are given, together with results obtained for patients with pheochromocytoma, chemodectoma, and congenital dopamine-beta-hydroxylase deficiency. The assay is sensitive, reproducible, and free of interferences, and may lead to a better understanding of overall catecholamine metabolism in health and disease.
Development and evaluation of an automated dye-binding assay for protein in cerebrospinal fluid.
Authors: Huang C M 
Published: January 2020

Abstract
Addition of sodium dodecyl sulfate (SDS) to Coomassie Brilliant Blue reagent equalizes the binding variability of the dye to various proteins and markedly improves the accuracy of quantification of protein in cerebrospinal fluid. In the presence of SDS, the absorption spectrum and the absorption maximum are affected by reaction time and temperature, age of the dye preparation, and protein constituent. I automated this procedure, to optimize precision, enable use of a smaller sample, decrease hands-on time, maintain consistency in the time of reading, and avoid carryover. The results (y) compared well with those of the aca (x), with a Deming de-biased regression equation of y = 0.991x + 14.1 mg/L, Sy.x = 33.4 mg/L. The within-run and between-run precision (CV) was less than 2.5% and less than 4.5%, respectively. Commonly used antibiotics, flucytosine, or amphotericin B do not interfere. This automated procedure is fast and accurate and requires only 10 microL of sample.
Concentrations of chromium, cesium, and tin in cerebrospinal fluid of patients with brain neoplasms, leukemia or other noncerebral malignancies, and neurological diseases.
Authors: el-Yazigi A , Martin C R , Siqueira E B 
Published: January 2020

Abstract
We measured the concentrations of chromium, cesium, and tin in the cerebrospinal fluid (CSF) of 29 patients with brain tumors [21 benign (BBT) and eight malignant (MBT)], 28 leukemic patients, 14 patients with lymphoma or noncerebral solid tumors (NLCT), and 32 control patients (15 with neurological disorders and 17 with noneurological conditions) by use of flameless atomic absorption spectrophotometry. We detected chromium in 94% of the patients, tin in 79%, and cesium in 50%. The mean (and SEM) concentrations (micrograms/L) of these metals in the control group were 4.7 (1.1) for chromium, 3.8 (1.6) for cesium, and 6.4 (1) for tin. We observed significant differences (P less than 0.05) in the concentration of chromium in CSF between the MBT group and all other tumor groups; the ratios for the mean CSF concentration of chromium in patients with BBT, leukemia, or NLCT to that in patients with MBT were 2.6, 2.1, or 4.4, respectively. We saw no significant differences in the concentrations of cesium or tin among the various groups investigated.
Evaluation of a new strategy for detection of thyroid dysfunction in the routine laboratory.
Authors: John R , Henley R , Lloyd G , Elder G H 
Published: January 2020

Abstract
We assessed the use of a new strategy for detecting thyroid disorders, utilizing a sensitive assay for concentrations of thyrotropin (TSH) and free thyroid hormone in serum as follow-up tests. Of 1279 patients who were not on thyroxin (T4) replacement treatment, 82% could be classified as euthyroid and would require no further tests. In patients who were on T4 replacement, 41% fell into the euthyroid category and would require no further tests. Using this strategy to replace our existing strategy of free thyroxin as a "first-line" test would reduce the proportion of patients who would require one or more follow-up tests from 49% to 24%.
Rapid sample preparation for determination of iron in tissue by closed-vessel digestion and microwave energy.
Authors: Van Wyck D B , Schifman R B , Stivelman J C , Ruiz J , Martin D 
Published: January 2020

Abstract
We developed a rapid acid-digestion method for preparing tissue samples for iron determination. Specimens were digested in nitric acid and hydrogen peroxide under high temperature and pressure in closed Teflon vessels, with microwave energy. Analysis for iron in 25- to 250-mg portions of digested bovine liver powder (National Bureau of Standards Certified Reference Material no. 1577a) showed excellent linearity ([predicted] = 1.007[actual] - 0.166 micrograms per sample) and analytical recovery (98%). Precision (CV) was 5.4% when iron content was 10 micrograms per sample. Assaying split samples of mouse tissues, we found a close correlation between iron concentrations obtained with closed vs open vessels ([closed] = 0.878[open] + 68 micrograms/g, r = 0.994, range 400-4600 micrograms/g dry weight). In contrast to time-consuming conventional procedures for tissue dissolution, closed-vessel digestion with microwave energy dramatically shortens time for tissue preparation, minimizes use of caustic acid, reduces risk of sample loss or contamination, and yields accurate and reproducible results.
IgG2 subclass deficiency: IgG subclass assays and IgG2 concentrations among 8015 blood donors.
Authors: Madassery J V , Kwon O H , Lee S Y , Nahm M H 
Published: January 2020

Abstract
Among the four IgG subclasses in humans, IgG2 is preferentially expressed in antibodies to carbohydrate antigens whereas IgG1 subclass is commonly associated with antibodies to protein antigens. Because of this association with carbohydrate antigens, values for IgG2 in serum are often used as an index of immunocompetence against carbohydrate antigens. To investigate the value of IgG2 measurements in a general population, we have developed a convenient IgG subclass assay, using monoclonal antibodies and particle concentration fluorescence immunoassay. Our assay is specific, precise, convenient, and accurate. When IgG2 concentrations were determined in the serum samples from 8015 adult blood donors, there were more individuals with low IgG2 concentrations than predicted by the log-normal distribution. The observed distribution suggested the presence of a subpopulation with low IgG2 concentration. Because apparently healthy individuals in a general population have low IgG2 concentrations, IgG2 measurements alone may have a limited clinical usefulness as an index of immune function against carbohydrate antigens.
The SimulTRAC FT4/TSH assay evaluated as a first-line thyroid-function test.
Authors: Desai R K , Deppe W M , Norman R J , Govender T , Joubert S M 
Published: January 2020

Abstract
We evaluated the SimulTRAC FT4 57Co/TSH 125I dual-isotope assay for the simultaneous measurement of free thyroxin (FT4) by radioimmunoassay analog techniques and of thyrotropin (TSH) by immunoradiometry. Inter- and intra-assay CVs were less than 10% over the entire range tested except for 15.9% at the lowest FT4 concentration. Results obtained by the SimulTRAC assay allowed complete differentiation of 85 hyperthyroid patients and 35 hypothyroid patients from normal subjects. However, such estimations of FT4 or TSH concentrations occasionally were misleading for assessing thyroid status in various clinical conditions. We conclude that the SimulTRAC assay has the same inherent disadvantages possessed by FT4 analog and TSH immunoradiometric assays; however, where results of one of the simultaneous assays may be misleading, the results provided by the other may indicate the underlying pathology without requiring an additional assay.
Familial occurrence of diminished pancreatic amylase in serum--a "silent" Amy-2 allelic variant?
Authors: Brock A , Mortensen P B , Mortensen B B , Røge H R 
Published: January 2020

Abstract
We describe a family of 32 subjects, including two healthy siblings without detectable pancreatic amylase in serum and five healthy relatives (one of them a sister) exhibiting subnormal pancreatic amylase activities. Comparisons of immunoreactive amylase concentrations with the corresponding amylase activities may justify the assumption of a "silent" Amy-2 allelic variant.
Three methods compared for isoamylase separation in tissue homogenates.
Authors: Whitten R O , Chandler W L , Thomas M G , Clayson K J , Fine J S 
Published: January 2020

Abstract
Using homogenates of autopsy tissue, we compared three widely available techniques for separating amylase isoenzymes: wheat-germ inhibition (WI), and electrophoresis on cellulose acetate (CA) or agarose (AG). WI separated amylase into two isoforms, CA into seven (three pancreatic and four salivary), and AG into nine (five pancreatic and four salivary). CA and WI had similar isoamylase detection limits (8-10 U/L) and similar imprecision in measuring percent S-type vs P-type isoamylase (within-run SD 1-2%), and they demonstrated a linear response to added S or P isoamylase. In contrast, the AG method had higher detection limits (10-15 U/L), greater imprecision (within-run SD 3%), and showed a nonlinear response to added S or P isomylase. We conclude that CA and WI have essentially equivalent assay attributes, superior to AG, but that CA resolves more amylase isoforms than WI.
A sensitive liquid-chromatographic method for determination of 3'-azido-3'-deoxythymidine (AZT) in plasma and urine.
Authors: Hedaya M A , Sawchuk R J 
Published: January 2020

Abstract
We describe a liquid-chromatographic assay for AZT in human plasma and urine. This assay involves the use of two internal standards, allowing reference of AZT peaks to the appropriate internal standard, the choice depending on the range of concentrations encountered. This method is isocratic, specific, sensitive enough to allow quantification of AZT in concentrations observed clinically, and requires only 13 min of chromatographic time. We saw no interference from various over-the-counter and prescription drugs often used in treating the infectious complications of AIDS.
Nontransferability of C-peptide measurements with various commercial radioimmunoassay reagents.
Authors: Koskinen P 
Published: January 2020

Abstract
I evaluated the between-method variation of C-peptide determined with C-peptide radioimmunoassay kit reagents from Mallinckrodt, Behring, Diagnostic Products Corp., and Immuno Nuclear Corp., and antisera from Novo (M1230, M1221, and K6) and Cambridge Medical Diagnostics (299-029P). C-peptide concentrations corresponding to 0.6 nmol/L (as determined with M1230) ranged from 0.54 (by Immuno Nuclear Corp.) to 1.06 nmol/L (by M1221). Furthermore, pretreating plasma specimens with Polyethylene Glycol 6000 variably decreased the results. Several factors may contribute to the between-method variation of C-peptide analyses: differences in the specificity of antisera, the type of C-peptide preparation used as standard and tracer, liability of the immunoassay to nonspecific interference, and possibly the heterogeneity of C-peptide immunoreactivity in the specimens.
Monoclonal-antibody-based noncompetitive avidin-biotin assay for lutropin in urine.
Authors: Vilja P , Wichmann L , Isola J , Tuohimaa P 
Published: January 2020

Abstract
This noncompetitive avidin-biotin assay for lutropin (LH) in urine is based on the use of solid-phase, monoclonal antibodies, avidin-biotin binding, and enzyme label. The detection limit for LH is 0.5 int. unit/L. Performance time is 2 h. Intra- and interassay CVs were 4.2% and 6.2%, respectively. The assay is more specific for intact LH than are RIAs, and the results are unambiguous as compared with those by RIAs. LH is stable for a week in refrigerated urine; thus urine is a convenient sample material in follow-up studies for clinical ovulation timing. This rapid and sensitive nonisotopic LH assay avoids the disadvantages of blood samples. The assay provides clinically relevant predictions of ovulation timing from the amount of hormone measured in a 3-h urine specimen.
Measurement of rimantadine in plasma by capillary gas chromatography/mass spectrometry with a deuterium-labeled internal standard.
Authors: Herold D A , Anonick P K , Kinter M , Hayden F G 
Published: January 2020

Abstract
Rimantadine is a synthetic antiviral agent used in prophylaxis and in treating the early stages of uncomplicated influenza A illness. We describe a stable isotope-dilution assay involving capillary gas chromatography/mass spectrometry. We used 200 ng of d3-rimantadine, added to 1 mL of plasma, as the internal standard. The rimantadine was extracted from the plasma with a Bond-Elut CN column, the column was washed with water, and the rimantadine was eluted with methanol, dried, and treated to form the t-butyldimethylsilyl derivative. The mass spectrometer was operated in the selected ion monitoring mode. Ions at m/z 236 and m/z 239 were monitored, corresponding to the loss of C4H9 from the rimantadine derivative and d3-rimantadine, respectively. Within-run precision (CVs) ranged from 8.9% at 29 micrograms/L to 3.2% at 1666 micrograms/L. Corresponding data for between-run precision were 5.4% and 1.7%. Treated volunteers (n = 86) provided plasma samples with a concentration range of 153 to 1127 micrograms/L. This simplified method allows rapid, precise assay of rimantadine in plasma.
Simple, rapid determination of zinc and acid phosphatase in seminal plasma with an ABA-100 bichromatic analyzer.
Authors: Gavella M 
Published: January 2020

Abstract
I describe an automated assay for zinc and acid phosphatase in seminal plasma. These, which are markers of the function of the prostate, were assayed bichromatically with an Abbott ABA-100 analyzer. As many as 25 samples of human seminal plasma can be analyzed sequentially with CVs of 3.1% for zinc and 1.5% for acid phosphatase. The sensitivity, specificity, and speed of this assay system make it practicable for use in investigation of male infertility.
Age- and sex-specific pediatric reference intervals for biochemistry analytes as measured with the Ektachem-700 analyzer.
Authors: Lockitch G , Halstead A C , Albersheim S , MacCallum C , Quigley G 
Published: January 2020

Abstract
Using the Ektachem-700 multilayer film analyzer, we defined age- and sex-specific reference intervals for 20 analytes in sera from a healthy population of neonates and children ages one to 19 years. Upper and lower normal reference intervals for each analyte were determined by nonparametric methods as the 0.975 and 0.025 fractiles, respectively. Newborns have lower concentrations of total protein and albumin, and higher concentrations of phosphate, bilirubin, and enzymes in serum than older children do. Concentrations of urea, glucose, calcium, phosphate, and bilirubin change rapidly postnatally. Outside the neonatal period, no significant age- or sex-related difference was found for plasma glucose, serum amylase, conjugated or unconjugated bilirubin, or lipase. There was no sex-related difference in reference intervals for albumin, total protein, calcium, phosphate, or urea. However, concentrations of uric acid and creatine kinase are much higher in postpubertal boys than in girls. Alkaline phosphatase values peak later in boys. Except for lactate dehydrogenase and gamma-glutamyltransferase, the reference intervals defined here do not differ strikingly from data derived with use of other analyzers. The age- and sex-related trends are independent of method. However, each laboratory should determine the degree to which these reference ranges can be directly applied to analyses performed with another analyzer.
Detection of protein binding abnormalities in euthyroid hyperthyroxinemia.
Authors: George P M , Sheat J M , Palmer B N 
Published: January 2020

Abstract
This is a procedure for rapidly identifying the three common abnormalities in binding of thyroxin by protein. After incubation with [125I]thyroxin, serum proteins are separated by electrophoresis on agarose gel and binding of thyroxin to the various protein fractions is determined after autoradiography. Quantitatively abnormal binding to albumin or prealbumin and thyroxin autoantibodies is easily demonstrated by this technique. Normally, less than 6% is bound to albumin, and no binding by prealbumin is detected. In dysalbuminemic hyperthyroxinemia, about 30% of the serum thyroxin is bound to albumin; in prealbumin-associated hyperthyroxinemia, 7% is bound to prealbumin. With this procedure these protein-binding abnormalities can be simply identified, and it may be useful when results of a thyroxin assay are not consistent with results of a sensitive thyrotropin assay or the patient's clinical examination.
Choriogonadotropin and its beta subunit separated by hydrophobic-interaction chromatography and quantified in serum during pregnancy by time-resolved immunofluorometric assays.
Authors: Alfthan H , Schröder J , Fraser R , Koskimies A , Halila H , Stenman U H 
Published: January 2020

Abstract
Concentrations of human choriogonadotropin (hCG) and its free beta subunit (beta hCG) were measured in serum by highly sensitive and specific time-resolved immunofluorometric assays (IFMAS). The results were confirmed by completely separating beta hCG and hCG by a novel method based on hydrophobic-interaction chromatography. We used three monoclonal antibodies in two different combinations. In both assays an antibody reacting with both free beta hCG and with intact hCG was immobilized onto the wall of a microtiter strip well. For assay of intact hCG we used as the indicator antibody an antibody against the alpha subunit, labeled with a europium chelate. For assay of beta hCG we used an indicator antibody that reacted only with the free beta subunit. hCG cross-reacted in the assay of beta hCG by 0.6%. Quantifying hCG in serum after in vitro fertilization showed that, seven to eight days after embryo transfer, the hCG concentration started to increase, thereafter increasing with a doubling time of 1.9 days during the following three weeks. hCG concentrations in serum peaked six to 10 weeks later, corresponding to eight to 12 weeks after the last menstrual period. Throughout pregnancy, measurable amounts of beta hCG were present in serum. The highest beta hCG/hCG ratio (maximum 7.3%, median 3.0%) was observed during early gestation. During the fourth to 13th weeks after the last menstrual period the ratio of beta hCG/hCG decreased gradually, being 1.0% during the second and third trimesters.