bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of assay conditions on cross reactivity of digoxin-like immunoreactive substance(s) with radioimmunoassay kits.
Authors: Pudek M R , Seccombe D W , Jacobson B E , Humphries K
Published: January 2020

One or more digoxin-like immunoreactive substances (DLIS), most frequently present in serum of premature and full-term neonates. cross react to various extents with different digoxin immunoassay kit reagents. Mostly, this variation is attributed to the relative cross reactivity of DLIS with the antiserum in each kit. However, modification of standard assay procedures for digoxin can also greatly alter the relative cross reactivity of DLIS. Using sequential RIA kit methods for digoxin by 20 to 60% relative to the standard equilibrium RIA mode. Cross reactivity was decreased still more if the concentrations of antiserum (binding-site concentration) and tracer (125 l-labeled digoxin) were decreased, and conversely. Serum samples containing only digoxin, analyzed by the modified method, consistently yielded results well comparable with those obtained with the manufacturers' recommended procedures. We describe use of the different responses to digoxin and DLIS of standard and sequential radioimmunoassays and use of simultaneous equation to calculate the concentration of DLIS (in digoxin equivalents) in digoxin-containing samples.
Improved radioimmunoassay for vitamin D and its use in assessing vitamin D status.
Authors: Hollis B W , Napoli J L
Published: January 2020

We describe a faster, more-sensitive radioimmunoassay for vitamin D in plasma. Antibodies were generated in rabbits immunized with a new vitamin D analog, the 23,24,25,26,27-pentanor-C(22)-carboxylic acid of vitamin D, coupled directly with bovine serum albumin. After several months, Rivanol-treated sera from the rabbits contained high-titer antibodies, as determined by their abilities to bind 25-hydroxy-[3H]cholecalciferol. The antibody, used at a 1:15 000 final dilution, cross reacted equally with all cholecalciferol and ergocalciferol metabolites tested except 1,25-dihydroxycalciferol metabolites and the parent calciferols. 25-Hydroxycalciferol and similar forms were efficiently extracted from plasma or serum with acetonitrile. We separated bound from free 25-hydroxy-[3H]cholecalciferol by using a second antibody: goat antiserum to rabbit serum. The detection limit of the assay was 3.0 pg of 25-hydroxycholecalciferol and its equivalents per tube; thus only 1 microL of plasma is needed per assay tube. Results compared well with those from a liquid-chromatographic procedure involving specific ultraviolet detection of 25-hydroxycalciferol in plasma.
Value of measuring C-terminal parathyrin in differential diagnosis of hypercalcemia.
Authors: Scott D P , Teasdale P R , Swaminathan R
Published: January 2020

We measured calcium, phosphate, chloride, albumin, C-terminal parathyrin, and beta 2-microglobulin in serum from 102 hypercalcemic patients: 42 with primary hyperparathyroidism and 60 with neoplasia. The calcium concentrations and the discriminant function index of Johnson et al. (Clin Chem 28, 333-338, 1982) were higher in malignant hypercalcemia than in primary hyperparathyroidism. The diagnostic efficiency of the index and of parathyrin concentration was 82% and 78%, respectively. Using the ratio of parathyrin to beta 2-microglobulin increased the diagnostic efficiency to 98%; the ratio of the discriminant index to parathyrin concentration had a diagnostic efficiency of 100%. We conclude that C-terminal assay by itself is no better than the discriminant function index.
Biochemical diagnosis and monitoring therapeutic modulation of disease activity in an unusual case of congenital erythropoietic porphyria.
Authors: Mukerji S K , Pimstone N R , Gandhi S N , Tan K T
Published: January 2020

We describe the methodology used for quantifying and characterizing porphyrins in various tissues and in excreta, in the diagnosis and monitoring of the therapeutic modulation of biochemical disease activity in a 53-year-old white man who has a rare form of familial porphyria cutanea tarda with bone marrow rather than hepatic expression of the disease. Liquid-chromatographic and thin-layer chromatographic analyses of the patients's urine and skin showed predominantly heptacarboxylic porphyrin and uroporphyrin, whereas his stool and bile contained isocoproporphyrin and coproporphyrin as the major products. The data reflect defective uroporphyrinogen decarboxylation. Both analytical methods gave quantitatively similar results for urinary and fecal porphyrins. A triple-lumen perfusion study of samples procured both at the ampulla of Vater and 15 cm downstream provided data for porphyrins excreted in the bile and their reabsorption in the small intestine. We evaluated: suppression by hypertransfusion of bone marrow overproduction of porphyrins and reduction of enteral absorption of porphyrins by orally administered charcoal (Acta Char) and cholestyramine.
Evaluation of dual-label simultaneous assays for lutropin and follitropin in serum.
Authors: Beinlich C J , Piper J A , O'Neal J C , White O D
Published: January 2020

We evaluated the analytical performance and clinical utility of three dual-label simultaneous assays for lutropin and follitropin by comparison with widely used individual assays for these analytes (Diagnostic Products Corp.; DPC). Of the three assays evaluated, "Cotropin" (Clinetics Corp.) and "Combostat" (Micromedics Systems, Inc.) compared favorably with the DPC assay with respect to recovery, linearity, intra- and inter-assay precision, and sensitivity for lutropin. The third assay evaluated, "Simultropin" (Becton Dickinson Immunodiagnostics), exhibited greater interassay variability for lutropin than did the DPC assay but otherwise compared favorably. Analytically the three assays were similar to one another for follitropin determinations and results compared favorably with those by the DPC assay. Intercorrelation of patients' results obtained with these assays is poor. However, using the same standards with each of the three assays improved intercorrelation of patients' data except for follitropin by Combostat. A universally accepted reference material for immunoassay of lutropin and follitropin is needed.
Effect of heat treatment on results for biochemical analysis of plasma and serum.
Authors: Houssein I , Wilcox H , Barron J
Published: January 2020

Incubation of serum and plasma samples at 56 degrees C for 30 min inactivates the HTLV-III virus. We assessed the effect of this procedure on results of routine biochemical tests by dividing samples of serum and plasma into two, heat-treating one while the other remained at room temperature. Samples were then analyzed in an SMA 16/60, an Astra-8, an Analox glucose analyzer, a Cobas Bio centrifugal analyzer, and manually for salicylate and acetaminophen (paracetamol). Most of the differences produced by heat treatment were not clinically significant, although heated samples proved unsuitable for use in assay of some commonly measured enzymes. Serum evidently is preferable to plasma for this procedure, and heat-treated serum samples can validly be used for most routine analyses. Thus this procedure makes safer the analysis of samples from patients with suspected or proven acquired immune deficiency syndrome (AIDS).
Phenylalanine analyses of blood-spot control materials: preparation of samples and evaluation of interlaboratory performance.
Authors: Spierto F W , Hearn T L , Gardner F H , Hannon W H
Published: January 2020

Aliquots (0.1 mL) of whole-blood pools prepared to contain various concentrations of phenylalanine were applied to filter-paper collection cards, dried, and stored in sealed bags. We measured the phenylalanine content of the dried blood spots by bioassay, fluorometry, and "high-performance" liquid chromatography, and found that the concentrations remained constant for two years when samples were kept at -20 degrees C or lower. Intra- and interlaboratory studies showed that results for phenylalanine were greater for laboratories using bioassay procedures than for those using fluorometric procedures. Further, CVs (both among- and within-laboratory) obtained with fluorometric procedures were nearly half as great as the CVs obtained by laboratories using bioassay techniques.
Relationships between magnesium and protein concentrations in serum.
Authors: Kroll M H , Elin R J
Published: January 2020

We determined concentrations of magnesium, total protein, albumin, and globulin in more than 74 000 serum specimens from patients and noted a direct linear relationship between the concentration of magnesium in serum and the concentrations of total protein, albumin, and globulin in serum. Albumin and magnesium concentrations are linearly related at high and low albumin concentrations; within the reference interval, however, the magnesium concentration is independent of the albumin concentration. Linear regression analysis suggests that 25% of the total serum magnesium is bound to albumin and 8% to globulins.
Stability of bombesin in serum, plasma, urine, and culture media.
Authors: Tateishi K , Klee G G , Cunningham J M , Lennon V A
Published: January 2020

Using a radioimmunoassay, we studied the stability of bombesin added to pooled human serum, plasma, urine, and two culture media (RPMI-1640 and M199). Bombesin was stable in serum for 5 h at 4 degrees C and 2 h at 21 degrees C. However, in plasma, about half was no longer detected by 5 h at 4 degrees C, and this decline was unaffected by added aprotinin. Bombesin was stable in urine for 24 h at 4 degrees C and for 2 h at 21 degrees C. When incubated in the culture media at 37 degrees C for 60 min, no loss was detected. Bombesin-like immunoreactivity was detectable in the serum of 22 mice bearing tumors established from biopsied small-cell lung carcinomas, two of 12 mice bearing tumors established from other malignancies and zero of nine control mice. In contrast, immunoreactivity to this analyte was detected in urine specimens from all mice except for one bearing a non-small-cell tumor. The concentrations detected in serum and urine were uncorrelated.
Factors influencing normal reference intervals for creatinine, urea, and electrolytes in plasma, as measured with a Beckman Astra 8 Analyzer.
Authors: Rodger R S , Laker M F , Fletcher K , White T F , Heaton A , Ward M K , Kerr D N
Published: January 2020

In a study of 514 healthy adults, we used a Beckman Astra 8 Analyzer to establish normal reference intervals for plasma creatinine, urea, and electrolytes. For potassium and chloride these were considerably lower and higher, respectively, than previously reported ranges. All of these analytes showed significant sex-related differences; all except chloride showed age-related changes. The relationship of these biochemical indices to fasting, cigarette smoking, alcohol intake, regular exercise, and the contraceptive pill--independent of these age- and sex-related differences--was assessed by multiple linear regression. The effect was significant in each case. Our results underline the importance of regular review of reference values.
An L-lactate sensor with immobilized enzyme for use in in vivo studies with an endocrine artificial pancreas.
Authors: Mascini M , Fortunati S , Moscone D , Palleschi G , Massi-Benedetti M , Fabietti P
Published: January 2020

We report the features of a sensor for determining L-lactate. An oxygen sensor, coupled to a nylon net with chemically bound L-lactate oxidase (EC 1.1.3.2), is inserted into an artificial pancreas (Biostator, Miles) "downstream" from the glucose sensor. We used the sensor to continuously monitor the L-lactate concentration in blood after a "glucose clamp" experiment with a diabetic patient. L-Lactate determinations in blood drawn from the patient every 15 min agreed well with results obtained by use of the L-lactate sensor.
Reliability of the Hitachi sodium and potassium electrodes assessed.
Authors: Winkel P , Wilken M , Christiansen J , Buch B
Published: January 2020

We compared the Hitachi 705 E sodium/potassium electrode system with the Radiometer flame photometer for measuring concentrations of sodium and potassium ions in serum and plasma. Our data show that the Hitachi results are slightly but significantly (less than 0.001) lower than the flame photometer results: Na+ 1.33 mmol/L for serum and 2.24 mmol/L for plasma; K+ 0.062 mmol/L for serum and 0.082 mmol/L for plasma. The magnitude of the bias varied considerably from day to day, ranging from -0.10 to 2.33 mmol/L for Na+ in serum and from 0.00 to 0.11 mmol/L for serum K+; for plasma specimens the corresponding ranges were -0.03 to 5.97 mmol/L and 0.00 to 0.17 mmol/L. These variations probably reflected difficulties in reproducing the calibration from day to day, because the daily means for a serum pool varied in parallel. We occasionally encountered serious problems with reproducibility.
Appearance of a cathodic band in the electrophoretogram of blood creatine kinase isoenzyme-MM fraction during hypoxia in rats.
Authors: Hayashi T , Tanaka T
Published: January 2020

In electrophoretograms of creatine kinase (CK; EC 2.7.3.2) in patients' blood, a band, presumably of mitochondrial origin, is occasionally observed on the cathodic side of the CK-MM fraction. We studied the implications of this phenomenon in rats exposed to hypoxic conditions. In the hypoxic cardiac muscle, the proportions of CK-MB and CK-MM were not significantly different from controls, but that of the mitochondrial CK was lower. In the corresponding blood, the cathodic mitochondrial CK band appeared, but disappeared as the animals recovered from hypoxia. The CK-MB isoenzyme was increased in the blood of the control rats, as obtained by heart puncture, but no mitochondrial fraction was detected. We believe that changes in myocardial mitochondria during hypoxia are related to the appearance of the cathodic band. Cytoplasmic CK-MB, unlike mitochondrial CK, markedly increased in the rats' blood during the recovery stage rather than during the hypoxia.
Use of a diode array detector in investigation of neonatal organic aciduria.
Authors: Allen K R , Khan R , Watson D
Published: January 2020

We investigated the use of a diode array detector in conjunction with isocratic cation-exchange liquid chromatography for detection of organic acids in urine. The spectra and retention times of abnormal peaks found on chromatography of urine from patients with methylmalonic aciduria, maple syrup urine disease, and lactic aciduria were recorded and compared with those obtained for group of pure organic acids. Our results show that diode array detection helps considerably in tentatively identifying peaks appearing on an abnormal chromatogram while awaiting confirmation by mass spectrometry.
Determination of urinary free cortisol by "on-line" liquid chromatography.
Authors: Schöneshöfer M , Kage A , Weber B , Lenz I , Köttgen E
Published: January 2020

This is a fully automated method for the specific assessment of urinary free cortisol. A 1-mL urine sample is concentrated and prepurified on a reversed-phase precolumn with alkaline, acid, and organic washes. After selective elution, the cortisol-containing organic eluate is "polarized" by admixing water in such a way that cortisol is focused on the top of a second reversed-phase precolumn. From this precolumn, cortisol is desorbed by backflush, separated from the still-remaining related compounds on an analytical column, and finally detected by ultraviolet absorbance. Losses of cortisol throughout the total procedure are negligible and thus external calibration is feasible for quantification. CVs were 4.1% for interassay variability, 2.6% for intra-assay variability. Cortisol concentrations down to 15 nmol/L are assayable, we estimated the median amount of free cortisol excreted daily by normal students, outpatients, hospitalized patients, and patients under intensive care. After stimulation with corticotropin1-24, the median concentration of free cortisol in urine increased from 99 nmol/L to 1238 nmol/L (n = 6). Results by radioimmunoassay for normal persons and hospitalized patients were about fourfold those by this technique. The same method can also be used for free cortisone in urine.
Precision of sensitivity estimations in diagnostic test evaluations. Power functions for comparisons of sensitivities of two tests.
Authors: Linnet K
Published: January 2020

The precision of estimates of the sensitivity of diagnostic tests is evaluated. "Sensitivity" is defined as the fraction of diseased subjects with test values exceeding the 0.975-fractile of the distribution of control values. An estimate of the sensitivity is subject to sample variation because of variation of both control observations and patient observations. If gaussian distributions are assumed, the 0.95-confidence interval for a sensitivity estimate is up to +/- 0.15 for a sample of 100 controls and 100 patients. For the same sample size, minimum differences of 0.08 to 0.32 of sensitivities of two tests are established as significant with a power of 0.90. For some published diagnostic test evaluations the median sample sizes for controls and patients were 63 and 33, respectively. I show that, to obtain a reasonable precision of sensitivity estimates and a reasonable power when two tests are being compared, the number of samples should in general be considerably larger.
Evaluation and comparison of a radiative energy attenuation method for determining cholesterol in serum.
Authors: Cary P L , Johnson C A , Whitter P D , Parker J W
Published: January 2020

Determination of cholesterol by a radiative energy attenuation (REA) technique was evaluated and compared with results obtained by the Boehringer Mannheim High Performance Cholesterol Assay and the Du Pont aca. Within-assay and between-assay CVs for the REA method, for two sets of controls, were both less than 5%. We observed no interference with lipemic samples. Analytical recovery averaged 102.8%. We used all three methods for parallel determinations of 217 patients' samples containing a wide range of cholesterol concentrations. Linear regression analysis of the REA results vs those of the comparison methods were as follows: REA = 1.03 Boehringer - 0.072 (r = 0.993) and REA = 1.02 aca - 0.048 (r = 0.995). We also discuss bilirubin interference with the REA method for cholesterol.
Liquid-chromatographic assay of cimetidine in plasma and gastric fluid.
Authors: Abdel-Rahim M , Ezra D , Peck C , Lazar J
Published: January 2020

In this micro-scale method for liquid-chromatographic measurement of cimetidine in 250-microL volumes of plasma or gastric fluid, a combination of organic- and aqueous-phase extractions, and protonation of the internal standard and cimetidine, enabled us to detect 2.0 ng of cimetidine on the column. We also used a radial compression module, which reduced the retention times for cimetidine and the internal standard to only 2.78 and 2.00 min. The speed and sensitivity of this method facilitates analysis of large numbers of samples.
Adenosine deaminase binding protein, a new diagnostic marker for kidney disease.
Authors: Thompson R E , Piper D J , Galberg C , Chan T H , Tolkoff-Rubin N E , Rubin R H
Published: January 2020

This enzyme immunoassay detects adenosine deaminase binding protein (ABP), a glycoprotein that is shed from the brush border of the proximal tubule in kidney damage. Two monoclonal antibodies, URO-4 and URO-4a, each react with different epitopes on ABP and are used as the "sandwich" pair of antibodies. A linear standard curve can be generated by using partly purified ABP isolated from the urine of patients with kidney disease. Release of ABP into the urine appears to reflect the severity of the insult to the nephron. Therefore, measurement of ABP in urine may help distinguish between tubular disease and glomerular disease and indicate renal allograft rejection in renal-transplant patients.
Liquid-chromatographic determination of ciprofloxacin in serum and urine.
Authors: Nix D E , De Vito J M , Schentag J J
Published: January 2020

We describe the liquid-chromatographic determination of ciprofloxacin in patients' serum and urine. Serum samples were prepared by precipitating protein with perchloric acid. Urine samples were diluted 100-fold with mobile phase. The mobile phase, consisting of pH 3 phosphate buffer/acetonitrile/methanol (81/5/14, by vol), was pumped through a mu Bondapak C18 reversed-phase column at 1.5 mL/min. Fluorescence of the effluent was monitored, at wavelengths for excitation and emission of 270 and 440 nm, respectively. Standard curves were linearly related to concentration from 0.08 to 10 mg/L for serum, 1 to 20 mg/L for urine. The procedure was evaluated in a clinical setting to determine its usefulness in studying the pharmacokinetics of ciprofloxacin in patients with concurrent diseases and receiving multiple drug therapies.
Gas-chromatographic determination of cholesterol in serum: candidate reference method.
Authors: Derks H J , van Heiningen A , Koedam H C
Published: January 2020

We present a candidate Reference Method for determination of total cholesterol in serum. The method is based on high-resolution capillary gas chromatography, and we took special precautions with respect to weighing, calibration, and chromatographic peak integration. Analytical recovery of added cholesterol was essentially complete (99.99%, SD 0.48%) and reproducibility was excellent (total CV 0.35-0.50%). When cholesterol was determined in a reference serum certified by means of an established candidate Definitive Method, no significant bias could be detected.
Differences in cerebrospinal fluid proteins between patients with schizophrenia and normal persons.
Authors: Harrington M G , Merril C R , Torrey E F
Published: January 2020

A survey of cerebrospinal fluid (CSF) proteins from normal persons and patients with schizophrenia reveals differences between the two populations. Computer-assisted densitometry of 68 proteins, resolved by two-dimensional electrophoresis and made visible by silver staining, shows six changes. Compared with their occurrence in the normal group, two proteins are increased in the schizophrenic patients by 22% and 27%, while four proteins are decreased by 29%, 46%, 20%, and 37% (p less than 0.005). Furthermore, two additional 40 000-Da proteins are found in CSF from 31.5% of the schizophrenic patients. Although these disease-associated proteins have not yet been found in 12 other neurological and psychiatric conditions, they have been found in patients with herpes simplex encephalitis (90%), Creutzfeldt-Jakob disease (67%), multiple sclerosis (13%), Parkinson's disease (12%), and a single case of Guillain-Barré syndrome. These two 40 000-Da proteins have never been found in CSF from any of 99 normal persons.
Determination of L-carnitine in serum, and implementation on the ABA-100 and CentrifiChem 600.
Authors: Rodriguez-Segade S , de la Peña C A , Paz J M , Del Rio R
Published: January 2020

Deproteinization of serum samples by heating to 100 degrees C, then freezing, allows up to 60% of the volume of the sample to be recovered. Concentrations of L-carnitine in samples so treated are comparable with those obtained by more sophisticated and expensive methods, and precision and accuracy are similar to those of other available techniques. There is no medically significant difference between results obtained in the ABA-100 and CentrifiChem 600, and the method is suitable for screening studies. Concentrations in the serum of presumably healthy adults ranged from 29.3 to 66.1 mumol/L. As little as 3 mumol of L-carnitine per liter can be determined.
Two-dimensional proton nuclear magnetic resonance "maps" of acetaminophen metabolites in human urine.
Authors: Bales J R , Nicholson J K , Sadler P J
Published: January 2020

Two-dimensional proton-proton correlated NMR spectra of concentrated urine from a subject who had ingested a 1-g dose of acetaminophen are reported. These "maps" provide a considerable simplification of the spectrum in comparison with conventional one-dimensional NMR spectra. In the present case, peaks for all the major acetaminophen metabolites, including the L-cysteinyl conjugate, can be unambiguously assigned.
Complete urinary excretion profile of 5-fluorouracil during a six-day chemotherapeutic schedule, as resolved by 19F nuclear magnetic resonance.
Authors: Bernadou J , Armand J P , Lopez A , Malet-Martino M C , Martino R
Published: January 2020

We determined the urinary excretion of 5-fluorouracil (5FU) and its metabolites during six days of chemotherapy, using the non-invasive approach of 19F nuclear magnetic resonance. With this method, which requires no labeled drug, one can study the biological sample directly and simultaneously identify and quantify all the fluorinated metabolites. The daily urinary excretion of 5FU and its metabolites was high (94.8% of 5FU administered) and nearly constant all during the treatment. By far the major excreted catabolite was alpha-fluoro-beta-alanine, which made up 78.9% of the total. Unchanged 5FU (10.8% of dose injected) was found only during the first 2 h after injection. We observed neither accumulation of 5FU nor modifications in its metabolism during the treatment.
Potentiometric measurements of ionized calcium in anaerobic whole blood, plasma, and serum evaluated.
Authors: Wandrup J , Kvetny J
Published: January 2020

The measurements of ionized calcium and pH in paired samples of anaerobic capillary whole blood, venous whole blood, venous plasma, and venous serum have been evaluated with a modified ICA 1 analyzer and compared with those of an unmodified ICA 1 analyzer. The unmodified instrument showed a significant difference between measurements in anaerobic venous whole blood, venous plasma, and venous serum, but the modified instrument did not. Statistically significant differences between the two instruments were found for whole blood (magnitude of mean difference magnitude of = 0.053 mmol/L) and for venous serum (0.016 mmol/L), but not for venous plasma. The error of residual liquid junction potential due to blood cells, previously found in the unmodified ICA 1 (salt bridge: KCl, 2.68 mol/kg) was eliminated and independent of the erythrocyte volume fraction in the modified ICA 1 (salt bridge: sodium formate, 4.56 mol/kg). From studies of procedures for measurements of ionized calcium in anaerobically handled samples, we recommend the use of anaerobic whole blood for measuring ionized calcium.
Use of dodecyl sulfate as an esterase inhibitor before gas-chromatographic determination of labile beta-adrenoceptor blocking drugs.
Authors: Holm G , Kylberg-Hanssen K , Svensson L
Published: January 2020

Sodium dodecyl sulfate (SDS) was introduced as an esterase inhibitor in the determination of two extremely labile, ultrashort-acting beta-blockers-esmolol and flumolol--in whole blood. SDS was much more efficient than previously used agents in preventing hydrolysis. The assay comprises solvent extraction, perfluoroacylation, and capillary gas-chromatography with electron-capture detection. The limit of detection (the concentration at which the coefficient of variation is 10-15%) for the drugs is 5 nmol/L of whole blood.
Effects of some anti-inflammatory drugs on 12 blood constituents: protocol for the study of in vivo effects of drugs.
Authors: Jelić-Ivanović Z , Spasić S , Majkić-Singh N , Todorović P
Published: January 2020

We investigated the in vivo effects of acetylsalicylic acid, diclofenac, indomethacin, ibuprofen, and ketoprofen on the concentrations of various blood constituents. Total protein, glucose, calcium, and inorganic phosphate were not significantly affected by any of these drugs. Ketoprofen had no definite influence on any constituent. Acetylsalicylic acid induced an increase in cholesterol, triglyceride, and iron; albumin, uric acid, and creatinine decreased with ibuprofen therapy. Urea nitrogen increased in patients treated with diclofenac or indomethacin. Our protocol for the study of in vivo drug effects is discussed.
Enzyme immunochromatography--a quantitative immunoassay requiring no instrumentation.
Authors: Zuk R F , Ginsberg V K , Houts T , Rabbie J , Merrick H , Ullman E F , Fischer M M , Sizto C C , Stiso S N , Litman D J
Published: January 2020

We describe a novel test-strip immunoassay for quantifying drugs in biological fluids. This enzyme immunochromatographic ("immunograph") method combines many features of the enzyme-channeling homogeneous immunoassay with immunochromatography and capillary migration to provide a non-separation, non-instrumental assay for theophylline in which quantification is based on the spatial distribution of enzyme label rather than on the modulation of enzyme activity. Sample antigen and hapten-enzyme conjugate are combined and moved by capillary action up a paper strip on which specific antibody has been immobilized. After color development, the assay result is evaluated by measuring the height of the colored zone on the test strip. Quantification is not a function of enzyme activity, so the method is relatively insensitive to sample matrix effects, enzyme instability, temperature, and incubation timing. Either whole blood or plasma can be used as sample. Results correlate well with those by established instrumental methods. The simple, rapid (15 min), two-incubation protocol is well suited for on-site testing in non-laboratory environments.
Determination of aluminum in bone by atomic absorption spectroscopy.
Authors: Smeyers-Verbeke J , Verbeelen D
Published: January 2020

In developing this method for determination of Al in bone we paid special attention to the homogenization of bone samples, which presents great difficulties for trace-element analysis. To minimize the risk of contamination, we preferred low-temperature ashing over classical wet-digestion techniques for destruction of the organic material. Graphite-furnace atomic absorption spectroscopy is used for measurement of Al. For Al concentrations exceeding 15 micrograms/g, direct standardization against a calibration line can be used (between-run CV, 5.9%). For Al concentrations within the normal range (less than 15 micrograms/g) the standard-addition technique should be applied. Comparison of results by the method with those by a procedure based on extraction of Al with a saturated solution of EDTA revealed that, although the latter method gave considerably lower results for three of 13 samples, there was no statistical difference between results by the two methods.
Activity of lactate dehydrogenase isoenzymes LD1 and LD2 in serum as determined by using an inhibitor of the M-subunit.
Authors: Tanishima K , Hayashi T , Matsushima M , Mochikawa Y
Published: January 2020

To measure activities of lactate dehydrogenase (EC 1.1.1.27) isoenzymes LD1 and LD2 in serum, we developed a method involving 1,6-hexanediol as specific inhibitor of the M-subunit. Addition of hexanediol, 0.6 mol/L, to five LD isoenzyme fractions purified from human liver and heart homogenates resulted in complete loss of activities of LD4 and LD5, and partial loss of LD2 and LD3. The activity of LD1, which is composed of the H-subunit only, was not affected. In studying what conditions would allow only the activities of LD1 or LD1 + LD2 to be expressed in serum, we found that the respective activities could be determined by treatment with hexanediol, 0.75 mol/L and 0.55 mol/L, respectively. Results of binding experiments and analytical-recovery tests supported the effectiveness of analyses with this inhibitor in determination of LD1 and LD1 + LD2 activities in serum. Results by this proposed inhibition method correlated well with those by the conventional electrophoretic method for determination of LD1 activity, but LD1 + LD2 activities by the inhibition method were a little less than those by the electrophoretic method, requiring some correction.
Immunochemical qualitative latex agglutination test for pancreatic lipase in serum evaluated for use in diagnosis of acute pancreatitis.
Authors: Møller-Petersen J , Klaerke M , Dati F , Toth T
Published: January 2020

In 417 patients (213 men, 204 women) consecutively hospitalized with acute abdominal pain we evaluated the clinical usefulness of a latex-agglutination test at admission to screen for concentrations of pancreatic lipase (EC 3.1.1.3) in serum greater than 300 micrograms/L. The diagnoses of acute pancreatitis (in 25 patients, 6%) and other diseases were made without knowledge of the results of the latex test or of quantification of pancreatic lipase in the serum by enzyme immunoassay. In the latex assay, when agglutination was taken as a positive test for acute pancreatitis, we found a diagnostic efficiency of 0.986 (95% confidence limits: 0.971-0.997) for acute pancreatitis. The predictive value of a positive latex test result with respect to acute pancreatitis was 0.807 (0.625-0.926); the predictive value of a negative test was 1.000 (0.991-1.000). Six patients had false-positive test results. No false-negative test results were found by enzyme immunoassay. We conclude that the latex agglutination test is useful as an emergency test for diagnosis of acute pancreatitis in patients with acute abdominal pain; negative results virtually exclude acute pancreatitis.
Spectrophotometric investigation of sensitive complexing agents for the determination of zinc in serum.
Authors: Homsher R , Zak B
Published: January 2020

Of two sensitive complexometric reagents for the colorimetry of serum zinc that we investigated, one, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP), was found to be a potentially useful compound for trace-metal determinations. It has a high molar absorptivity (120 000 L mol-1 cm-1) but is not convenient to use because it is not very soluble in water. The other reagent, a related pyridylazo compound, is 2-(5-bromo-2-pyridylazo)-5-(N-n-propyl-N-3-sulfopropylamino)phenol (5-BR-PAPS). It seems better suited for use in routine zinc determinations because, besides being water soluble, it has a higher molar absorptivity, 130 000 L mol-1 cm-1. Results by the proposed method developed with 5-Br-PAPS correlated well with those by atomic absorption spectrophotometry. The between-run CV for control sera was less than 5%; the within-run CV (same controls) was less than 4%.
Three techniques compared for detecting bacteriuria in symptomatic patients.
Authors: Warkentin D L , Rawling R A , Koppel W E , Maher G L , Broder P H , Marchand A
Published: January 2020

We wanted to determine whether the microscopic evaluation of urinary sediment could be replaced by either a biochemical determination (Chemstrip-9) or a colorimetric staining procedure (Bac-T-Screen), and to evaluate the feasibility of omitting from urinalyses attempts to culture urines. Cultures were considered positive when colony counts were greater than or equal to 10(3) for catheterized patients and greater than or equal to 10(4) for noncatheterized patients. The results of three separate studies on symptomatic patients showed a progressive decline in the sensitivity of the Chemstrip-9, which is a test for leukocyte esterase activity, and a difference in the sensitivity of the Bac-T-Screen between two of the studies. Neither test was consistently more sensitive or more predictive of a positive culture than was urine microscopy. By the end of the third study, we were convinced that the three methods are comparably sensitive and specific. Because 13 to 36% of positive cultures would be missed by these techniques, urine from symptomatic patients should routinely be cultured.
Application of a statistical approach to determining reference intervals in clinical chemistry.
Authors: Gallo C , Turco M C , Sanzi G , La Rocca S , Sacchetti L , Salvatore F
Published: January 2020

In clinical chemistry a linear-regression model may be used to determine reference intervals. A crucial point in this approach is the choice of variables to introduce into the model. In the present paper, we have applied a nonautomatic selection procedure, known as "element analysis," to a sample of 126 individuals from a small, ethnically homogeneous community in southern Italy. We investigated the effects of four independent variables--sex, age, weight, and alcohol consumption--on values for serum urea. Only sex and age proved to affect the urea values and were therefore introduced into the final model. This approach may be useful in determining reference intervals from observational studies when it is difficult to control a priori relevant factors. Moreover, variables may be selected not only on the basis of statistical criteria, but also according to biochemical and medical criteria.
Kinetic assay of gamma-glutamyltransferase with use of bilirubin oxidase as a coupled enzyme.
Authors: Satomura S , Miki Y , Hamanaka T , Sakata Y
Published: January 2020

We studied the kinetic measurement of gamma-glutamyltransferase (EC.2.3.2.2), coupling the reaction with that catalyzed by bilirubin oxidase (EC 1.3.3.5), which oxidizes and combines a phenylenediamine derivative with an aniline derivative to produce a green pigment. We measured the formation of the pigment kinetically (at lambda max745 nm, epsilon = 75 000 L mol-1 cm-1), with L-gamma-glutamyl-N-hydroxyethylaminoanilide as substrate and N-ethyl-N-hydroxy-3-sulfopropyl)-m-toluidine as a the coupling derivative. The within-run CV for measuring this reaction in samples of normal sera was 2.4%. A calibration plot of the change in absorbance per minute vs enzyme activity concentration showed good proportionality in the range of 0-1300 U/L. The results of this assay correlated well (r = 0.995) with those of the Boehringer method, in which L-gamma-glutamyl-3-carboxy-4-nitroanilide is the substrate. This new, highly sensitive procedure may be adapted to other assays involving phenylenediamine derivates as synthetic substrates.
Bioelectrochemical enzyme immunoassay of human choriogonadotropin with magnetic electrodes.
Authors: Robinson G A , Hill H A , Philo R D , Gear J M , Rattle S J , Forrest G C
Published: January 2020

We describe an amperometric technique for quantification of an enzyme immunoassay in which we use a magnetic working electrode, both to separate bound and free analyte and to monitor the electrochemical response. We used a "two-site" immunometric assay with monoclonal antibodies for human choriogonadotropin (hCG) as a model system in which magnetic particles were used as the solid phase. Separation of bound and free label is readily achieved by localizing the particles at the electrode. Activity of the bound enzyme in the environment of the electrode is determined electrochemically, permitting rapid quantification of the analyte without the need for a separate incubation step to measure enzyme activity. The sensitivity of the system is 150 int. units of hCG per litre (1st Int. Ref. Preparation). Correlation between the amperometric measurement of urinary hCG and data for an immunoradiometric assay was r = 0.9. The assay is rapid, requiring a total assay time for each sample of 20 min, which includes 15 min for antibody/antigen binding.
A quantitative automated immunoassay for fibrinogen/fibrin degradation products.
Authors: Schifreen R S , Cembrowski G S , Campbell D C , Craig A R , Demyanovich N D , Jurga-Hall P A , Reider M C , Schwartz M W , Tuhy P M , Waller S J
Published: January 2020

We describe a prototype quantitative automated assay for fibrin and fibrinogen degradation products, a particle-enhanced turbidimetric inhibition immunoassay (PETINIA) in the Du Pont aca discrete clinical analyzer. This assay involves a latex particle reagent with covalently bound fibrinogen and a polyclonal antiserum raised in rabbits against human fibrinogen. A special secondary sample-collection tube quantitatively removes fibrinogen from citrated plasma and inhibits further fibrinolysis, independent of heparin concentration. The assay range is 0-100 mg/L, in fibrinogen equivalents. The CV for the assay is less than 10% when performed with the aca. Nonclottable fibrin and fibrinogen fragments are measured by the assay, the greatest sensitivity being directed at the E domain of the fibrinogen molecule. We illustrate with case studies the potential of this assay for providing clinical information not obtainable with currently available qualitative and semi-quantitative assays.
Enzymatic correction of interference in the kinetic Jaffé reaction for determining creatinine in plasma.
Authors: Boyne P , Robinson B A , Murphy P , McKay M
Published: January 2020

We evaluated a simple, specific method for measuring plasma creatinine concentration, involving enzymatic degradation of creatinine before analysis by a kinetic Jaffé reaction. The enzymes--prepared in a dry, stable form--are convenient to use and eliminate the need to correct for sample dilution. As little as 50 microL of plasma is required, making the procedure ideal for use with samples from children. Between-day precision studies for determination of plasma creatinine at concentrations of 70 and 470 mumol/L yielded CVs of 7.8 and 4.3%, respectively. Analytical recovery of creatinine added to plasma samples ranged from 94 to 113%. Linear regression analysis demonstrated excellent agreement between results by this method and those by a "high performance" liquid-chromatographic technique.
Combined Immunochemical and Electrophoretic Determinations of Proteins in Paired Serum and Cerebrospinal Fluid Samples
Authors: Papadopoulos N M , Costello R , Kay A D , Cutler N R , Rapoport S I
Published: January 2020

Vol. 30

p 1815: The SD in the second column of the Table should read "0.09," not "0.9."

Vol 31

p 95, right column, last paragraph: The units for the protein concentrations should be mg/L.
Measurement of transferrin in human seminal plasma by a chemiluminescent method.
Authors: Caldini A L , Orlando C , Barni T , Messeri G , Pazzagli M , Baldi E , Serio M
Published: January 2020

We describe a luminescence immunoassay for measuring transferrin in human seminal plasma. Human transferrin conjugated with 7-[(N-4-aminobutyl)-N-ethylamino]naphthalene-1,2-dicarboxylic acid hydrazide was used to monitor the immunological reaction. The conjugate was stable for at least one year. The sensitivity (2 ng per tube) of the assay allows measurement of this protein in diluted seminal plasma. Results by this method (y) correlated well (r = .9681) with those by a conventional RIA method (x): y = 1.000x + 1.646 micrograms per ejaculate. Seminal transferrin concentrations are reported for normal control subjects, vasectomized subjects, and infertile patients. The method described appears suitable for measurement of seminal transferrin as an index of Sertoli cell function in male infertility.
Triclonal gammopathy in a patient with plasma cell dyscrasia.
Authors: Ray R A , Schotters S B , Jacobs A , Rodgerson D O
Published: January 2020

A triclonal gammopathy is an immunoglobulin abnormality in which three discrete monoclonal subpopulations of immunoglobulin molecules are present in a patient's serum. Monoclonal and biclonal gammopathies have been studied extensively, but relatively little is known about the much rarer triclonal gammopathies. The case described below illustrates some of the difficulties that this condition can present to the clinician and the clinical laboratory.
Urinary excretion rates of 15 free steroids: potential utility in differential diagnosis of Cushing's syndrome.
Authors: Schöneshöfer M , Weber B , Oelkers W , Nahoul K , Mantero F
Published: January 2020

To evaluate their potential usefulness in the differential diagnosis of Cushing's syndrome, we estimated the urinary excretion rates of the following non-metabolized, unbound steroid hormones: pregnenolone, progesterone, 17-OH-pregnenolone, 17-OH-progesterone, dehydroepiandrosterone (DHEA), androstenedione, testosterone, dihydrotestosterone, 11-deoxycorticosterone, 11-deoxycortisol, corticosterone, cortisol, 18-OH-11-deoxycorticosterone, 18-OH-corticosterone, and aldosterone. These were measured in normal subjects and in patients with Cushing's disease, adrenal adenoma, or ectopic corticotropin syndrome. We used "high-performance" liquid chromatography and subsequent radioimmunoassay. Our results indicate that simultaneous estimation of urinary free cortisol and DHEA may be useful in differential diagnosis of hypercorticoid states due to adrenal adenoma and Cushing's disease.
The chemistry of aluminum as related to biology and medicine.
Authors: Martin R B
Published: January 2020

The increasing number of roles discovered for Al3+ in physiological processes demands an understanding of how Al3+ interacts with compounds in biological systems. Al3+ is expected to complex with oxygen donor ligands, especially phosphates, and it does so in soils, in the gastrointestinal tract, and in cells. The stability of Al3+ complexes has generally been misjudged because of lack of recognition that free, aqueous Al3+ is not the dominant form in neutral solutions and that the solubility of Al(OH)3 limits the free Al3+ at the plasma pH 7.4 to less than 10(-11) mol/L. In the presence of inorganic phosphate, the permitted free Al3+ is decreased further, through formation of insoluble aluminum phosphate. This precipitate facilitates the elimination of Al3+ from the body. In contrast, citrate solubilizes Al3+, and an appreciable fraction occurs as a neutral complex that may pass through membranes and provide a vehicle for Al3+ absorption into the body. In the blood plasma the most likely small-molecule complex is that with citrate, while the only competitive protein complex is that with transferrin, a protein built to transport Fe3+ but whose sites are only 30% occupied.
Diagnostic significance of some urinary enzymes for detecting acute rejection crises in renal-transplant recipients: alanine aminopeptidase, alkaline phosphatase, gamma-glutamyltransferase, N-acetyl-beta-D-glucosaminidase, and lysozyme.
Authors: Jung K , Diego J , Strobelt V , Scholz D , Schreiber G
Published: January 2020

We compared the diagnostic validity of five urinary enzymes--alanine aminopeptidase (EC 3.4.11.2), alkaline phosphatase (EC 3.1.3.1), gamma-glutamyltransferase (EC 2.3.2.2), N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30), and lysozyme (EC 3.2.1.17)--as indicators of acute rejection crises in renal-transplant recipients. In 82 patients (group A), the excretion of each of these five enzymes was measured daily from transplantation until discharge from hospital. In another 69 patients (group B), enzyme determinations were made when the patient came for regular checkups (about every four to eight weeks). We used an "activity ratio" (the activity measured at a particular time compared with the activity on the preceding determination) value of 1.5 as the decision point. In group A, use of this discrimination point for alanine aminopeptidase, gamma-glutamyltransferase, and N-acetyl-beta-D-glucosaminidase yielded a specificity and sensitivity of about 90%. In group B, only alanine aminopeptidase had a greater diagnostic sensitivity than creatinine alone. Evidently, measurement of alanine aminopeptidase can be a helpful indicator of acute rejection crises, when interpreted in combination with other available relevant clinical, biochemical, and immunological data.
Relationship between serum lactate and ionized calcium in open-heart surgery.
Authors: Toffaletti J , Christenson R H , Mullins S , Harris R E
Published: January 2020

We studied 16 patients undergoing open-heart surgery and heart-lung bypass, to examine the relationship between ionized calcium and lactate. Blood was sampled at successive stages of the operation for measurement of ionized and total calcium, lactate, blood gases, pH, hematocrit, and other constituents. We found that correlations between ionized calcium and lactate were positive and statistically significant (p less than 0.05), both among and within patients. The linear regression of ionized calcium on lactate remained highly significant (p less than 0.0001) after adjustment for variability among patients and across operative stages as well as after correction for pH and hemodilution. The significant regressions between calcium and lactate, both before and after administration of calcium, indicate a relationship for calcium and lactate in patients undergoing open-heart surgery.