bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid solid-phase immunoassay for 6-keto prostaglandin F1 alpha on microplates
Authors: Schramm W , Smith R H , Jackson T M , Craig P A , Grates H E , Minton L L
Published: January 2020

We describe, for the measurement of 6-keto prostaglandin F1 alpha in biological media, a solid-phase immunoassay with immobilized antibodies that requires a total processing time of less than 2 h with hands-on time less than 30 min for 40 samples. The method combines the convenience of the microplate format with the sensitivity of radiolabeled prostaglandin derivatives as tracers in a competitive immunoassay. The intra- and interassay variations at 50% displacement of the radiolabeled prostaglandin derivative as tracer were 9.0% and 11.8%, respectively. At 50% displacement of the radiolabeled tracer, the sensitivity is about 20 pg per well. Optimal incubation time is between 60 and 90 min. Nonspecific binding was less than 1% if about 8 pg of tracer (approximately 25,000 counts/min per well) was used. Inhibition curves of samples in different dilutions were parallel to standard curves. The variation of bound radiolabeled prostaglandin derivative within the wells of one microplate (n = 96) was less than 3%. Human plasma samples and medium from tissue culture assayed for 6-keto prostaglandin F1 alpha correlated well with results obtained with a solid-phase assay based on use of magnetic particles (r = 0.99, n = 24 for culture-medium samples; r = 0.99; n = 26 for plasma samples.
Flocculation of serum lipoproteins with cyclodextrins: application to assay of hyperlipidemic serum
Authors: Sharma A , Anderson K , Baker J W
Published: January 2020

We describe the complexation of isolated and native lipoproteins by natural macrocyclic polymers of glucose ("cyclodextrins"). Treatment of serum with cyclodextrin produces an immediate flocculation of the lipoproteins. The formation of cyclodextrin-lipoprotein complexes was evident on agarose electrophoresis gels. The concentration-dependent ability of alpha-cyclodextrin to precipitate chylomicrons and very-low-, low-, and high-density lipoproteins was used for clarifying lipemic serum. Results for normal and lipemic patients' specimens for some routinely measured analytes showed a good correlation between cyclodextrin treatment and ultracentrifugation. Unlike the use of organic solvents or ultracentrifugation, the proposed system provides a simple, mild, non-hazardous, and effective means for removing interfering lipid particles from biological specimens.
Exercise-induced proteinuria in well-trained athletes
Authors: Clerico A , Giammattei C , Cecchini L , Lucchetti A , Cruschelli L , Penno G , Gregori G , Giampietro O
Published: January 2020

We studied the rate of urinary excretion of albumin, alpha 1-microglobulin (as an indicator of the renal tubular involvement), sodium, potassium, and creatinine in the basal state (overnight urine collection) and after physical exercise (training session) in 10 professional cyclists, to verify whether protein excretion is increased even in well-trained athletes after physical effort. In addition, we wanted to understand whether the origin of exercise-induced proteinuria was glomerular, tubular, or both. Compared with the basal state (overnight collection), exercise significantly (P less than 0.01) increased the excretion rate of albumin (4.2 +/- 2.6 micrograms/min vs 18.1 +/- 10.6 micrograms/min, mean +/- SD), Na, and K, and also the urinary volume. Creatinine output was not affected by exercise. The mean (+/- SD) overnight excretion rate of albumin by athletes was quite similar to that found for 91 healthy nonathletes at rest (4.6 +/- 2.7 micrograms/min). The mean exercise-related excretion of alpha 1-microglobulin by the athletes significantly exceeded the overnight value (6.6 vs 0.3 mg/L, P = 0.037). Our study indicates that (a) albuminuria furnishes the greater contribution to the increase in exercise-induced proteinuria; (b) the exercise proteinuria is both glomerular and tubular in origin, and is reversible; (c) the enhanced protein requirement of athletes may in part be due to the recurrent excretion of proteins in the urine after physical effort.
Hyperparathyroidism in a patient with Wilson's disease
Authors: Tallis G A , Kitchener M I , Thomas A C
Published: January 2020

We describe hyperparathyroidism in an 18-year-old man with Wilson's disease--the first report in the English literature of the simultaneous occurrence of these two conditions.
An enzyme immunoassay for galactosyltransferase isoenzyme II, and its clinical application to cancer diagnosis
Authors: Uemura M , Yamasaki M , Yoshida S , Uezima T , Sakaguchi T , Okaniwa K
Published: January 2020

In this "sandwich"-type enzyme immunoassay of galactosyltransferase isoenzyme II (GT-II), we used the monoclonal antibody MAb 3872 previously established and characterized to be specific for GT-II. Plastic beads coated with MAb 3872 were incubated with serum and buffer, washed, then incubated with MAb 3872 conjugated with horseradish peroxidase and again washed. Peroxidase activity remaining on the beads was measured by color development with o-phenylenediamine. The assay standard curve was linear from 0 to 150 kU/L. Inter- and intra-assay CVs were less than 9% and less than 7%, respectively. Mean GT-II values for 370 normal controls were 6.8 (SD 3.4) kU/L with no significant sex-, smoking-, or blood-type-related differences. We also assayed serum from patients with 11 different cancers or with matched benign diseases. The diagnostic sensitivity of GT-II for liver and esophageal cancer was 0.91 and 0.72, respectively, apparently higher than for carcinoembryonic antigen (CEA) or alpha-fetoprotein. GT-II and CEA concentrations in sera were not correlated. Evidently this assay may be useful as a cancer diagnostic test to supplement existing serological methods.
Investigation of interference by nonsteroidal anti-inflammatory drugs in urine tests for abused drugs
Authors: Rollins D E , Jennison T A , Jones G
Published: January 2020

Anecdotal and uncontrolled studies have suggested that nonsteroidal anti-inflammatory drugs produce false-positive results in immunoassay urine tests for some drugs of abuse. This study was performed in 60 volunteers who took ibuprofen as either a single 400-mg dose, or 200 mg three times a day, or 400 mg three times a day, and in 42 patients taking ibuprofen, naproxyn, or fenoprofen in therapeutic regimens for more than 30 days. Of the 510 urines collected from 102 individuals during these dosage regimens, two gave false-positive tests for cannabinoid by enzyme-mediated immunoassay (EMIA), one after 1200 mg of ibuprofen in three divided doses for one day and one in a patient taking naproxyn on a chronic basis; none was falsely positive for benzodiazepines. Two urines were false-positive for barbiturates by fluorescence polarization immunoassay (FPIA), one in a patient taking ibuprofen and one in a patient taking naproxyn. These data, collected prospectively, demonstrate the small likelihood of a false-positive immunoassay test result for cannabinoids, benzodiazepines, or barbiturates after the acute or chronic ingestion of ibuprofen, or after the chronic ingestion of naproxyn or fenoprofen.
Determination of carbamylated hemoglobin by high-performance liquid chromatography
Authors: Kwan J T , Carr E C , Bending M R , Barron J L
Published: January 2020

We have developed an HPLC method for measuring carbamylated hemoglobin (CarHb), based on the quantification of valine hydantoin formed from the released NH2-terminal carbamyl valine residue after acid hydrolysis of hemoglobin. In uremia, CarHb is produced by nonenzymatic post-translational modification of the terminal amino group of hemoglobin monomers by isocyanic acid, derived from the spontaneous dissociation of urea. We measured CarHb in 25 nonuremic control subjects, 24 nonuremic diabetic subjects, and 30 patients with stable chronic renal failure. There was no significant difference between the controls and diabetic patients, their mean (SD) CarHb values being 41 (11.5) and 38 (10.8) micrograms of carbamyl valine per gram of hemoglobin (microgram CV/gHb), respectively. Mean (SD) CarHb values in the uremic patients were much greater, 164 (87.7) microgram CV/gHb. There was significant correlation between the concentrations of CarHb and plasma urea in the uremic subjects. Thus CarHb provides a urea-derived index of chronic uremia.
Measuring free thyroxin by using magnetic antibody-containing microcapsules
Authors: Wallace A M , Aitken S , Duffy F A , Fraser W D , Beastall G H
Published: January 2020

We describe a novel magnetic-separation microencapsulated antibody displacement assay for free thyroxin. The method is rapid (results available in just over an hour), with a detection limit of 3 pmol/L, and an interassay precision of less than 10% over the range 8-75 pmol/L. Results are not influenced by changes in the concentration of thyroxin-binding globulin or albumin, nor by the presence of circulating anti-thyroxin antibodies or physiological concentrations of nonesterified (free) fatty acids. A reference interval of 8.4-18.4 pmol/L was established for a large euthyroid adult population. Patients with various nonthyroidal illnesses exhibited a similar reference interval (6.2-17.4 pmol/L). Results from pregnant women, at all stages of gestation, were within the nonpregnant euthyroid reference interval. Complete discrimination was obtained between the euthyroid reference interval and values from patients with untreated thyrotoxicosis (24-75 pmol/L). Excellent, though incomplete, discrimination was obtained for patients with untreated hypothyroidism (less than 3.0-9.0 pmol/L). Results for a group of patients defined as having compensated euthyroidism (5.0-15 pmol/L) showed considerable overlap with the euthyroid reference interval. Patients taking thyroxin, who were clinically euthyroid and whose serum concentration of thyrotropin was within its euthyroid reference interval, had free thyroxin concentrations in the range 13.4-24.2 pmol/L. We discuss the validity of this assay in clinical practice.
Effects of 3-deoxyglucosone on the Maillard reaction
Authors: Igaki N , Sakai M , Hata H , Oimomi M , Baba S , Kato H
Published: January 2020

We investigated the effect of exogenously applied 3-deoxyglucosone, a major carbonyl intermediate, on the Maillard reaction. The fluorescence intensity of the product of the reaction of bovine serum albumin with 3-deoxyglucosone was higher than that with an equivalent amount of glucose. Similarly the rate of polymerization of lysozyme in the presence of 3-deoxyglucosone was also greater than with glucose, and collagen incubated with 3-deoxyglucosone was less digestible than collagen incubated with glucose. By contrast, aminoguanidine inhibited an increase in fluorescence of the Maillard compounds and the polymerization of protein, both of which were stimulated by 3-deoxyglucosone. These results suggest that 3-deoxyglucosone accelerates the advanced stage of the Maillard reaction and that aminoguanidine acts on 3-deoxyglucosone to inhibit its action in the advanced stage of the Maillard reaction.
Specificities compared for a radioreceptor assay and a radioimmunoassay of atrial natriuretic peptide
Authors: Capper S J , Smith S W , Spensley C A , Whateley J G
Published: January 2020

The main active form of atrial natriuretic peptide (ANP) in the circulation is alpha ANP(1-28) [gamma-ANP(99-126)], although some active and inactive metabolites are also though to be present. Some immunoassays for alpha ANP reportedly detect inactive metabolites, as determined by their comparison with results by receptor assay, which would lead to misleading results for alpha ANP(1-28) measurements. Here we compare a radioreceptor assay (RRA) and a radioimmunoassay (RIA) for alpha ANP and show that their results correlate very well with regard to specificity and that the RIA appears to detect only the active circulating form of alpha ANP(1-28).
Improved method of analysis for aluminum in brain tissue
Authors: van Ginkel M F , van der Voet G B , de Wolff F A
Published: January 2020

To improve the accuracy and precision of the assay of aluminum in brain tissue, we modified for application to brain samples from rats and humans the wet-digestion method of Trapp et al. (Biol Psychiatry 1978; 13:709-18), established the contribution of contamination, and examined the effect of precipitation of nonoxidizable fatty residues on the analysis. Specifications of the modified assay are a detection limit of 5 ng of aluminum per gram wet weight of brain tissue, a within-day CV of 4.8% (24.3 microgram/L; n = 10), and a day-to-day CV of 5.5% (27.8 micrograms/L; n = 5). Contamination, a systematic error in the analysis of aluminum, was established to be 13 ng (SD = 7.9 ng; n = 8) per tube. The presence of indestructible fatty residues did not affect the accuracy of the method. Application of the method to brain hemispheres of nonexposed rats revealed an aluminum content of 0.041 mg/kg wet weight of tissue (SD = 0.032 mg/kg; n = 8). The aluminum content in human cortex samples, consisting of gray and white matter, ranged from 0.14 to 0.22 mg/kg. Modification of the wet-digestion method resulted in a reliable, simple sample pretreatment before analysis for aluminum in brain tissue. The extent of the aluminum contamination must be controlled by including appropriate blanks.
Polyclonal antibody-based enzyme-linked immunosorbent assay of alpha 1-acid glycoprotein
Authors: Tissot B , Seta N , Durand G , Feger J
Published: January 2020

This is a noncompetitive enzyme-linked immunosorbent assay for measuring low concentrations (2 to 100 micrograms/L) of human alpha 1-acid glycoprotein (AGP; orosomucoid). The method is based on a simple "sandwich" technique involving polyclonal rabbit antisera against AGP. Mean within-run and total (between-run) CVs were 6.2% and 9.7%, respectively. Analytical recovery, tested in various biological fluids, averaged 101%. The technique has been successfully applied to diluted biological fluids such as bronchoalveolar lavage, cerebrospinal and amniotic fluids, and hepatocyte-culture supernates. Because of its analytical validity and the commercial availability of the reagents, this assay is suitable for large-scale determinations of AGP concentrations in those biological fluids in which its concentration is relatively low.
Use of free and transthyretin-bound retinol-binding protein in serum as tests of vitamin A status in humans: effect of high creatinine concentrations in serum
Authors: Burri B J , Bankson D D , Neidlinger T R
Published: January 2020

We measured immunologically active (apo + holo) retinol-binding protein (RBP), vitamin A-carrying (holo) free RBP, and transthyretin-bound (TTR) holo-RBP in serum from 34 retrospective cases of fluctuating acute renal failure. All subjects had high serum creatinine concentrations caused by renal failure. Apo + holo, holo-TTR-RBP, and (especially) holo-free RBP all correlated poorly but significantly with serum creatinine concentration. Therefore, the use of any form of RBP to measure vitamin A status may be of limited value in subjects with high creatinine concentrations in serum. However, molecular-exclusion HPLC may be able to distinguish increases in RBP concentration associated with renal failure from those caused by altered vitamin A status, because renal failure causes abnormalities in the number and retention times of chromatographic peaks as well as their areas.
New automated measurement of mitochondrial aspartate aminotransferase with use of protease 401
Authors: Watazu Y , Uji Y , Sugiuchi H , Okabe H , Murao S
Published: January 2020

Total mitochondrial aspartate aminotransferase (EC 2.6.1.1), the sum of apo- and holo-mitochondrial aspartate aminotransferase activity in human serum, was measured by using a proteolytic method: inactivation of cytosolic aspartate aminotransferase with cytosolic aspartate aminotransferase-inactivating protease 401 from Streptomyces violaceochromogenes. Cytosolic aspartate aminotransferase is completely inactivated, and apo-mitochondrial aspartate aminotransferase is completely activated by pyridoxal 5'-phosphate within 5 min. Results by the proposed method correlated well with those by an immunochemical method (r = 0.994, n = 145) and showed excellent inhibitory activity of the protease for holo- and apo-cytosolic aspartate aminotransferase up to 5000 U/L and activation of mitochondrial apo-aspartate aminotransferase up to 2000 U/L in the presence of 100 mumol of pyridoxal 5'-phosphate per liter. Within-run Cvs were good (1.13-7.49%). Mean values for total mitochondrial aspartate aminotransferase and apo-mitochondrial aspartate aminotransferase activities in serum of the healthy subjects were 4.8 (SD 0.9) and 1.8 (SD 0.8) U/L, respectively (n = 154). Various common interferents tested did not affect this assay.
Invalidity of hand heating as a method to arterialize venous blood
Authors: Green J H , Ellis F R , Shallcross T M , Bramley P N
Published: January 2020

We have assessed in normal subjects the validity of using hand heating to obtain "arterialized" venous blood by biochemical comparison of results for "arterialized" venous and true arterial (radial artery) blood samples. The heating regimen involved placing one hand in an air-heated box at 45-50 degrees C for 45 min. This method produced blood that was "arterialized" for lactate, PCO2, HbO2, and Hb but not for ammonia or PO2; it had no effect on determinations of pyruvate or glucose in plasma. Despite using a lower air temperature than previous workers, we observed thermal injury in one volunteer. Further, there was considerable between-subject variation in the effect of hand heating on blood gases. This suggests that blood gases should be measured in the "arterialized" samples at regular intervals from the start of hand heating in each patient to determine whether maximal "arterialization" has been achieved, to avoid making misleading biochemical measurements. Given the wide range in degree of observed "arterialization," we question the validity of this method.
Optimized preservation of isoforms of creatine kinase MM isoenzyme in plasma specimens and their rapid quantification by semi-automated chromatofocusing
Authors: Abendschein D R , Fontanet H L , Nohara R
Published: January 2020

We report a convenient chromatofocusing procedure for rapid and sensitive quantification of isoforms of the MM isoenzyme of creatine kinase (EC 2.7.3.2) in plasma and efficient methods for preserving isoform profiles during handling of specimens. The assay involves use of prepacked, re-usable Mono P chromatofocusing columns and a "Fast Protein Liquid Chromatograph" (FPLC) system with on-line detection of isoform enzymatic activity in column effluent. Profiles of isoforms are analyzed within 25 min with the use of a 1-mL column; the lower limit of sensitivity for CK activity is 5 mU, and recovery of each isoform is within 1% of the amount added to plasma. Collection of blood specimens in Vacutainer Tubes containing 28.5 mumol of EDTA (final concentration in plasma, 7 to 10 mmol/L) inhibited carboxypeptidase activity in plasma by 76%, sufficient to essentially abolish isoform conversion in vitro at room temperature. These methods should facilitate applications of isoform analysis for diagnosis of myocardial infarction and coronary artery recanalization.
Radial "high-performance" thin-layer chromatography used to assess fetal lung maturity
Authors: Mackenzie J R , Truesdale M
Published: January 2020

A radial "high-performance" thin-layer chromatographic (HPTLC) method is described by which the percentages and ratios of phosphatidylinositol, sphingomyelin, lecithin, phosphatidylethanolamine, phosphatidylglycerol, and dimethyl phosphatidylethanolamine may be determined simultaneously. An additional method for radial HPTLC determination of saturated phosphatidylcholine is described. We report results of application of these methods to greater than 2000 specimens of amniotic fluid from both diabetic and nondiabetic cases.
Variations in abundance of the molecular ion of the derivatized cocaine metabolite benzoylecgonine
Authors: Bodor G , Roggeman R , Turk J
Published: January 2020

Benzoylecgonine (BEG) is the principal urinary metabolite of cocaine. For forensic drug testing, the presence of BEG in urine, suggested by a positive result for a screening immunoassay, must be confirmed by quantitative gas chromatographic/mass spectrometric (GC/MS) analysis, i.e., stable isotope dilution with a deuterium-labeled internal standard. GC/MS criteria for positivity also require appropriate relative abundances of qualifier ions, including the molecular ion, but there is little published information on the observed absolute values for qualifier ion ratios or on the variability of these values. This lack of information creates uncertainty for laboratories initiating programs testing urine for drugs of abuse as to performance criteria for run acceptability and sample positivity. We have observed substantial variability (CV = 50%) in the abundance of the molecular ion of derivatized BEG relative to the base ion in reference materials. This variability can result in a high rate of repetition of runs and generate confusion in the defense of forensic drug-testing results. Normalization of the abundance of the molecular ion of derivatized BEG to that of the deuterium-labeled internal standard in the same sample greatly reduces the apparent variability in this measurement; it is also more reliable than the absolute value of the relative abundance of the molecular ion in determining run acceptability and positive or negative results for a sample.
Rapid and simultaneous determination of lactulose and mannitol in urine, by HPLC with pulsed amperometric detection, for use in studies of intestinal permeability
Authors: Fleming S C , Kapembwa M S , Laker M F , Levin G E , Griffin G E
Published: January 2020

The lactulose/mannitol dual sugar absorption test is a non-invasive test of intestinal permeability. Its widespread use has been limited by the difficulties of analysis for carbohydrates in urine at low concentrations. We describe a "high-pressure" liquid-chromatographic method for determining lactulose and mannitol in urine, in which anion-exchange chromatography and pulsed amperometric detection are used. Sample preparation is simple and fast, and lactulose and mannitol and the internal standards arabinose and cellobiose are well resolved within 15 min. Analytical response of the method is linear with concentrations to 3 g/L, and one can detect as little as 0.3 mg of lactulose per liter of urine. Analytical recovery was between 90% and 107% for all sugars analyzed, and there was good agreement with results by a gas-chromatographic method (r = 0.993 lactulose, 0.984 mannitol). The method may potentially be applied to the study of other carbohydrates present in biological fluids at low concentrations.
New ultrafiltration method for free thyroxin compared with equilibrium dialysis in patients with thyroid dysfunction and nonthyroidal illness
Authors: Tikanoja S H , Liewendahl B K
Published: January 2020

This new ultrafiltration method for free thyroxin in serum [FT4(U)] is based on radioimmunoassay of the free hormone fraction in ultrafiltrates obtained by centrifuging serum samples in Unisep Ultracent-10 ultrafiltration devices. We compared the results obtained with those by an equilibrium dialysis method [FT4(D)]. In 36 euthyroid healthy subjects, the mean FT4(U) concentration was 24.2 pmol/L and the mean FT4(D) concentration 14.8 pmol/L. In hyperthyroid and hypothyroid patients, results by the ultrafiltration method were also approximately twice as high as those obtained by the dialysis method. In 23 patients with various nonthyroidal illnesses, mean FT4(U) was 41.2 pmol/L and mean FT4(D) 19.8 pmol/L. The mean FT4(U)/FT4(D) ratio in patients with nonthyroidal illnesses (1.97) was not significantly higher than in control subjects (1.68), making it unlikely that the increase in serum FT4 is caused by weakly protein-bound and therefore dialyzable inhibitors of thyroxin binding to carrier proteins. However, two nonthyroidally ill patients with a clearly increased FT4(U) but a normal FT4(D) concentration might have had such inhibitors, whereas for two other nonthyroidally ill patients a high molar ratio of free fatty acids to albumin is a more likely explanation for increased FT4(U) and FT4(D) concentrations. On theoretical grounds, we consider the FT4(U) concentrations analytically more nearly accurate than FT4(D) values for all patient groups studied.
Therapeutic monitoring of cyclosporine: impact of a change in standards on 125I-monoclonal RIA performance in comparison with liquid chromatography
Authors: Keown P A , Glenn J , Denegri J , Maciejewska U , Seccombe D , Stawecki M , Freeman D , Stiller C , Shackleton C , Cameron E
Published: January 2020

This study examines the measurement of cyclosporine (CsA) by 125I-monoclonal RIA, and describes the impact of the recent change in the standard curve provided. CsA concentrations in serum and whole-blood control samples measured by 125I-RIA were initially 8-18% higher than those by HPLC. During the first two months of 1989, a significant and sustained deviation in the 125I-RIA produced results that exceeded the HPLC results by 21-28% (P less than 0.001). Introduction of the new standard curve in March 1989 returned the concentration of the whole-blood controls to the previous range (11-12% above HPLC, P less than 0.001). Measurement of clinical samples from heart, liver, and bone-marrow graft recipients by 125I-RIA by both old and new kit standards produced a close linear correlation (y = 0.89 x - 19.02; r = 0.99; n = 75, range = 40-850 micrograms/L), with use of the new standards yielding results 82 (SD 8)% of those with the preceding assay. However, even with the new standard curve, CsA concentrations by 125I-RIA in the clinical samples exceeded those by HPLC by a factor of 1.37 (SD 0.18) to 1.52 (SD 0.19). Segregation for transplant type did not affect the RIA/HPLC ratio. The results suggest cross-reactivity of the 125I-RIA with material present in vivo.
Benzalkonium interference with test methods for potassium and sodium
Authors: Koch T R , Cook J D
Published: January 2020

Six automated instruments that measure sodium and potassium were tested for interference from two compounds used in catheters. Tridodecylmethylammonium heparin did not interfere with any of the methods. However, benzalkonium heparin falsely increased sodium measurement with the Kodak Ektachem, and falsely increased potassium measurements with three instruments (Beckman Astra, Baxter Paramax, and the Instrumentation Laboratory Monarch) in which ion-selective electrodes measure potassium in diluted serum. Three instruments in which ion-selective electrodes measure serum directly--Du Pont Dimension, Abbott Spectrum, and Kodak Ektachem--experienced no interference with potassium measurements. Interference of benzalkonium with potassium measurements may result from its interaction with the electrode membranes, which is accentuated in diluted serum.
Transient hyperglycemia during abdominal aortic surgery
Authors: Ellison D A , Forman D T
Published: January 2020

A 64-year-old man undergoing abdominal aortic aneurysm repair with no history of diabetes mellitus had an episode of marked hyperglycemia during surgery. The peak concentration of glucose in plasma was 43.2 mmol/L. This hyperglycemia responded immediately to administration of 30 units of regular insulin. Factors involved in the hyperglycemia included surgical stress, multiple medications, and the anesthetic used (isoflurane), but do not fully account for the magnitude of the increase in glucose. The data suggest that the patient may have had an underlying insulin deficiency, which was unmasked by the stress of surgery.
Determination of creatinine in serum and urine by a rapid liquid-chromatographic method
Authors: Paroni R , Arcelloni C , Fermo I , Bonini P A
Published: January 2020

We describe an HPLC ion-pair procedure for rapid and specific evaluation of creatinine in serum and urine. We used a 15 cm X 4.6 mm ODS column with a 50/50 (by vol) mixture of sodium decanesulfonic acid (10 mmol/L, pH 3.2) and methanol and measured absorbance at 236 nm. Serum (100 microL) or 30-fold-diluted urine (100 microL) was added to 400 microL of acetone. After centrifugation, the supernates (300 microL) were dried, reconstituted with the mobile phase, and injected into the HPLC. Assay precision was tested for concentrations of 10, 29, and 130 mg/L and yielded, respectively, 3.1%, 2.1%, and 1.1% for within-day CV and 2.8%, 2.1%, and 2.2% for total CV. Analytical recovery was 102 (+/- 6.7%). Linearity was demonstrated in the 0-200 mg/L range for serum and 0-3.5 g/L range for urine (r greater than or equal to 0.999). The detection limit for creatinine (signal-to-noise ratio = 3) was 0.5 mg/L. We used cimetidine for internal standardization. Correlation was good between this procedure and the Jaffé kinetic, the enzymatic (creatinine amidohydrolase), and the Fuller's earth alkaline picrate methods.
Ultrafiltrable copper and related analytes in maternal and cord blood
Authors: Noubah A M , al-Awqati M A
Published: January 2020

We utilized the Amicon micropartition system (MPS-1) to prepare ultrafiltrates of serum for evaluating non-protein-bound copper (NPBCu). The method is rapid (a usual turnaround time less than 2 h), practical (only 1 mL of serum is required), and reproducible (average CV = 5.7% within assay and 9.3% between assays). Using this technique, we determined that (a) NPBCu in serum appeared to be fairly stable, showing little variation among subjects in different physiological conditions (normal female, pregnancy, or fetal samples); and (b) of all copper fractions studied, only NPBCu appeared to correlate between maternal concentrations and cord counterparts at delivery. Thus the NPBCu fraction may be appreciably involved in the overall mechanism of copper nutritional supply from mother to fetus.
Evaluation of automated urinary iodine methods: problems of interfering substances identified
Authors: May W , Wu D , Eastman C , Bourdoux P , Maberly G
Published: January 2020

We evaluated automated methods for measurement of urinary iodine (UI) over a range expected in iodine-replete and iodine-deficient populations. Results obtained with Technicon AutoAnalyzer II systems, based on either dialysis or acid digestion, were compared with those obtained by a manual alkaline ashing technique. Results of automated dialysis were consistently higher than those obtained by the other methods. The apparently higher concentrations of UI we measured were due to interfering substances crossing the dialysis membrane and participating in the catalytic reaction. Thiocyanate (SCN) was one endogenous substance contributing to the increased measurement of UI. For urinary SCN concentrations of 5 to 15 mg/L, the amount of overestimation in the UI measurement attributable to SCN ranged from 21.8 to 61 micrograms/L. However, SCN may account for only 40-50% of the apparent increase in UI. In samples with lower UI (less than 50 micrograms/L), interfering substances produced a 100% error in results. We conclude that the automated dialysis system should not be used to assess iodine-deficient populations. This leaves a major dilemma for researchers wanting to assess the iodine status of populations, because the automated digestion method is no longer commercially available.
Interference by human anti-mouse antibody in two-site immunoassays
Authors: Kricka L J , Schmerfeld-Pruss D , Senior M , Goodman D B , Kaladas P
Published: January 2020

Studies with goat and rabbit anti-mouse antibody, as models of human anti-mouse antibody (HAMA), have shown that several of the commonly used two -site immunoassays (e.g., for CA-125, carcinoembryonic antigen, choriogonadotropin, lutropin, hepatitis B surface antigen, thyrotropin) are susceptible to interference by this type of bridging heterophile antibody. In most cases the interference can be blocked by incubation with mouse IgG. We studied HAMA interference in an assay of hepatitis B surface antigen by using HAMA-positive sera from a transplant patient given OKT3 and from a cancer patient given CYT-103 (modified antibody B72.3). The HAMA interference attributable to the OKT3 could be blocked by incubation with mouse IgG at room temperature. In contrast, the interference caused by the B72.3-induced HAMA could be blocked by prolonged incubation with high concentrations of the B72.3 antibody at 4 degrees C. A limited survey of 50 hospital patients selected without conscious bias revealed two HAMA-positive patients, only one of whom was known to have been exposed to mouse immunoglobulin. HAMA interferences are currently a minor problem in routine laboratory medicine, but the increasing use of diagnostic and therapeutic products involving mouse-origin monoclonal antibodies will make the detection and elimination of HAMA interferences an important part of laboratory practice in the future.
Convenient screening for hemoglobin variants by using the Diamat HPLC system
Authors: Delahunty T
Published: January 2020

Hemolysates from 102 different patients previously assessed for the presence of hemoglobin variants by cellulose acetate electrophoresis were reanalyzed with the Diamat, a microprocessor-controlled step-gradient HPLC technique designed to determine glycohemoglobin (Hgb A1c). This pool contained 81 abnormal specimens, each with one of seven different variant abnormalities. In all cases the HPLC technique correctly detected the presence or absence of a variant. The common S trait gave a large peak immediately after Hgb A, and the SS and SC variants gave clearly abnormal patterns, caused in part by the absence of Hgb A. The pattern from EE variants was distinguished by the appearance of the glycated fraction Hgb E1c, which is eluted at 4.7 instead of 4.2 min, whereas the AE pattern had two glycated peaks. Hemoglobins F, "fast", S, and C were discerned by the presence of a major peak at 3, 5.2, 6.5, and 7.5 min, respectively. The findings suggest that the Diamat is a convenient tool to detect and help diagnose variants in a screening pool.
Effects of recombinant leukocyte interferon on ribonuclease activities in serum in chronic hepatitis B
Authors: Tsuji H , Murai K , Akagi K , Fujishima M
Published: January 2020

Alkaline ribonuclease (RNase; EC 3.1.27.5) activities and 2',5'-oligoadenylate synthetase (2-5 AS; no EC no. assigned) activities in serum were measured in nine patients with hepatitis B e antigen-positive chronic hepatitis B before, during, and after treatment with recombinant human interferon alpha-2b for four weeks at daily doses ranging from 3 to 10 mega-units. Alkaline RNase activities in serum significantly increased from 65.8 +/- 9.5 units/L (mean +/- SD) to 84.3 +/- 11.9 units/L after the first week of therapy (P less than 0.001). (One unit of RNase activity is defined as that increasing the absorbance at 260 nm by 1.0 in 1 min). This increase persisted during and until two weeks after the end of the therapy, at which time the mean RNase activity in serum was still significantly increased (70.8 +/- 9.4 units/L, P less than 0.01). Before therapy, phosphocellulose chromatography of RNase showed five active peaks of enzyme activity, which were similar to that observed even when RNase activity increased immediately after therapy. There was a close correlation between RNase activities and the logarithm of 2-5 AS activities, measured simultaneously in each patient. We conclude that recombinant alpha-interferon therapy increases RNase activities in serum, associated with the increased 2-5 AS activities.
Reference values of magnesium and potassium in mononuclear cells and erythrocytes of children
Authors: Geven W B , Vogels-Mentink G M , Willems J L , de Boo T , Lemmens W , Monnens L A
Published: January 2020

Reference values for magnesium and potassium contents of mononuclear cells and erythrocytes were estimated in cord blood and in children from infancy through adolescence. No differences were detected between results for boys and girls. The mononuclear magnesium content was independent of age and was within the adult range of values. No significant correlation was shown between magnesium in serum and in mononuclear cells. Mononuclear potassium also showed no age-related differences. The correlation between magnesium and potassium contents in mononuclear cells was significant: however, the correlation was lower when the magnesium and potassium contents were expressed in terms of protein potent: micromoles or millimoles per gram of protein, respectively. The concentration of magnesium in erythrocytes was significantly lower in cord blood and during the first month of life, compared with that at older ages, and showed no significant correlation with serum magnesium. The concentration of erythrocyte potassium was independent of age and showed a low but significant correlation with erythrocyte magnesium content.
Radioimmunoassay of the carboxyterminal propeptide of human type I procollagen
Authors: Melkko J , Niemi S , Risteli L , Risteli J
Published: January 2020

Type I collagen is the most abundant collagen type in soft tissues and the only type found in mineralized bone. We established a rapid equilibrium radioimmunoassay for the carboxyterminal propeptide of human type I procollagen (PICP), to be used as an indicator of the synthesis of type I collagen. We isolated type I procollagen from the medium of primary cultures of human skin fibroblasts, digested the protein with highly purified bacterial collagenase, and purified PICP by lectin-affinity chromatography, gel filtration, and ion-exchange separation on HPLC. The purity of the protein was verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by N-terminal amino acid sequencing of its component chains. The final radioimmunoassay was established with polyclonal rabbit antibodies. Material antigenically related to PICP is readily detected in human serum. There is only one form of the serum antigen, its molecular size and affinity to the antibodies being similar to those of the isolated propeptide. Intra- and interassay CVs are 3% and 5%, respectively. Preliminary reference intervals for healthy adults (18 to 61 years of age) are 38-202 micrograms/L for men and 50-170 micrograms/L for women: in men the concentration is inversely related to age. The serum antigen is stable during storage and after repeated thawing.
Use and abuse of imprecision profiles: some pitfalls illustrated by computing and plotting confidence intervals
Authors: Sadler W A , Smith M H
Published: January 2020

Published estimates of the imprecision characteristics of immunoassays are often based on quantities of data that seem to be inadequate. The increasing use of imprecision profiles has not necessarily improved the situation. We describe and illustrate a method of computing 95% confidence intervals for profiles estimated directly from replicated assay results. The data used were chosen to mimic the sort of data that are typically available in practice, either within laboratories or from external quality-assessment programs. Use of confidence intervals is an effective pictorial way of incorporating information about the quantity and the distribution of the data used for estimation. This is in keeping with an important property of imprecision profile plots: potentially complex information is summarized in a readily comprehensible way. A computer program is available for estimating and plotting profiles and their 95% confidence intervals.
Factors affecting the concentrations of ferritin in serum in a healthy Australian population
Authors: Leggett B A , Brown N N , Bryant S J , Duplock L , Powell L W , Halliday J W
Published: January 2020

We measured by different techniques the ferritin concentration in serum in two large asymptomatic Australian population samples: 1367 bank employees and 601 insurance corporation employees. Ethanol intake, diet, the frequency of blood donation, smoking and exercise habits, and past medical history were documented. The median concentration of ferritin in serum varied according to age and sex, but was generally higher than in previously reported populations under age 65 years. Results for the two population samples were in close agreement. Apart from the blood donation status, the most important factors influencing the concentration of ferritin in serum were ethanol intake in men and diet in women. Heavy ethanol intake was associated with increased values, even among men without evidence of liver disease. We conclude that the reference range for ferritin concentration in serum in the Australian population should be significantly increased and should be related to age as well as sex. This study emphasizes the need to determine local reference ranges for ferritin concentrations in serum.
Effects of storage time and temperature on measurement of small concentrations of albumin in urine
Authors: Osberg I , Chase H P , Garg S K , DeAndrea A , Harris S , Hamilton R , Marshall G
Published: January 2020

Accurate measurement of albumin excretion rates is important in choosing treatment regimens that may reverse early diabetic renal damage. We report here determinations of slight albuminuria ("microalbuminuria") by radioimmunoassay of fresh specimens, frozen aliquots (stored at -20 degrees C for two, eight, and 24 weeks), and refrigerated specimens (stored at 4 degrees C for one, two, and eight weeks). Seven separate analyses were performed on 101 specimens of urine obtained from 37 subjects with insulin-dependent diabetes mellitus and from 10 nondiabetic healthy controls of a similar age. Storage of urine samples at -20 degrees C resulted in significantly lower measurements of microalbuminuria than in fresh urine (ANOVA, corrected for repeated measures: P = 0.01 to 0.0001). In contrast, storage of urine samples at 4 degrees C for as long as eight weeks did not significantly affect urinary albumin results. The pH values of the specimens were minimally altered and were not a likely cause of the decreased albumin values in the frozen specimens. We conclude that urine specimens for microalbuminuria measurements should either be analyzed as fresh specimens or stored at 4 degrees C and assayed as soon as possible.
Relative increase in creatine kinase MB isoenzyme during reperfusion after myocardial infarction is method dependent
Authors: Christenson R H , Clemmensen P , Ohman E M , Toffaletti J , Silverman L M , Grande P , Vollmer R T , Wagner G S
Published: January 2020

We compared relative increases in creatine kinase (EC 2.7.3.2) MB isoenzyme (CK-MB) after reperfusion in myocardial infarction for four popular methods: electrophoresis, immunoinhibition, the "Magic Lite" (Ciba-Corning) system, and the Stratus (Dade). In a method comparison study, we confirmed that all four methods correlated (r greater than 0.95). Electrophoresis demonstrated the greatest scatter about the regression line, immunoinhibition the least. For CK-MB quantities near each method's "positive cutoff" indicating myocardial infarction, results by all methods agreed in 95% of samples. To characterize relative increases in CK-MB, we computer-fitted data obtained from each method for serial specimens collected from six acute myocardial infarction patients during myocardial reperfusion. Although for each individual patient the four methods appeared to exhibit parallelism, the methods differed significantly in terms describing their appearance rate, peak-time & fall-off, and time-to-peak activity. Consistent with these data, we found that the relative CK-MB increases at various times after reperfusion, compared with baseline concentrations, are method-dependent. Therefore, when using CK-MB for indicating coronary patency, one must develop specific limits for each method utilized.
Silicon measurement in serum and urine by direct current plasma emission spectrometry
Authors: Roberts N B , Williams P
Published: January 2020

Elemental silicon, present as soluble silicic acid in serum and urine, has been measured by direct current plasma emission spectrometry. The method is precise and accurate, yields a standard curve that is linear up to 1000 mumol/L, and requires only a simple dilution in 10 mL/L HNO3. No spectral or background interferences have been observed from serum or urine; the absolute detection limit for silicon was 0.5 mumol/L. Silicon concentrations in serum increase by up to 20-fold in patients with chronic renal failure on hemodialysis, an increase apparently related to dietary silicon intake. No relationship with aluminum was observed in hemodialysis patients, with or without aluminum toxicity. In the undialyzed patient with chronic renal failure, the concentrations of silicon in plasma increased with decreasing glomerular filtration rate. This increase may protect renal-failure patients from possible aluminum toxicity by promoting formation of the relatively inactive aluminosilicate complex. Silicon concentrations in urine of healthy individuals exceed their serum concentrations by 20- to 100-fold. Silicon excretion in patients with renal stones was not different from that in healthy controls and showed no relationship with calcium and (or) oxalate excretion.
Bromide interference: is less really better?
Authors: Emancipator K , Kroll M H
Published: January 2020

Increased serum bromide may result from the ingestion of various drugs and from environmental exposures. Chloride methods that are less susceptible to bromide interference have a clinical disadvantage in that they are less likely to arouse suspicion in cases of bromide toxicity. When there is a clinical suspicion of bromide toxicity, differences among various analyzers in the amount of interference caused by bromide may be exploited to confirm this suspicion and to estimate the concentration of bromide in serum.
Determination of free progesterone in an ultrafiltrate of saliva collected in situ
Authors: Schramm W , Smith R H , Craig P A , Paek S H , Kuo H H
Published: January 2020

We have investigated the utility of an ultrafiltrate of saliva for measuring progesterone as an indicator of luteal function during the menstrual cycle of women. A filtrate of saliva is collected in the mouth by means of an osmotic pump that accumulates medium containing only molecules less than 12,000 Da. We analyzed the nonextracted ultrafiltrate by a solid-phase immunoassay for progesterone and monitored the mid-luteal surge of lutropin in urine with a liquid-phase radioimmunoassay. Progesterone concentrations in the ultrafiltrate are significantly lower during the follicular phase and increase after the release of lutropin. The concentration of progesterone in the ultrafiltrate correlates closely with total progesterone in matched blood samples (r = 0.84, cycle 1; and r = 0.89, cycle 2). Likewise, we found a good correlation between the results in whole saliva and in the ultrafiltrate (r = 0.95). The described method of obtaining a pre-processed specimen noninvasively simplifies the self-collection of samples by patients (including collection at home); excludes potential interference from microorganisms, desquamated cells, and salivary components; and simplifies the processing of the biological fluid in the laboratory.