bluuebunny/crossref_metadata_2025 huggingface dataset:
Semi-automated fluorometry of total estrogens in plasma during late pregnancy.
Authors: Goutte-Coussieu C , Sanchez D , Adessi G , Jayle M F
Published: January 2020

We describe a mechanized method for determining total estrogens in plasma during the last trimester of pregnancy. This method involves rapid enzymic hydrolysis, automatic extraction (in a tube) with cyclohexane/ethyl acetate, purification of the extracted material by anion-exchange chromatography on a disposable “mini-column” of Dowex AG1 X 2 (acetate form), and continuous-flow fluorometric quantification. Conditions of hydrolysis and extraction were studied. The mean within-day imprecision (CV) was 7% and between-day imprecision was 8.1%. Sensitivity was 75 nmol/L of plasma. Results are obtained in 4 h. The technique is quite suitable for routine determinations: 90 assays can be done by a team of three technicians in one working day.
Simultaneous liquid-chromatographic determination of three antiarrhythmic drugs: disopyramide, lidocaine, and quinidine.
Authors: Flood J G , Bowers G N , McComb R B
Published: January 2020

We report a common methodology for determining three antiarrhythmic drugs: disopyramide, lidocaine, and quinidine. Alkalinized serum and internal standard (p-chlorodisopyramide) are extracted into dichloromethane, the organic phase is evaporated, and the redissolved residue is injected onto a reversed-phase column (micron Bondapack C18). Quantitation is via peak-height ratios of analyte vs internal standard (as detected at 205 nm) referenced to a serum-based multiple-drug standard. A mobile phase of 30 mmol/L phosphate buffer and acetonitrile (72/28 by vol) is used. These conditions yiel; optimum separation and band symmetry for the analytes and some of their metabolites. Crucial factors in this simultaneous assay include pH of the mobile phase and injected solution, extraction time, and evaporation technique. Day-to-day precision (CV) for all drugs was less than 5%, and correlation with other assay techniques for each drug is reported. The method enables more efficient use of personnel and instrumentation without sacrificing analytical quality.
Simultaneous liquid-chromatographic determination of zinc protoporphyrin IX, protoporphyrin IX, and coproporphyrin in whole blood.
Authors: Gotelli G R , Wall J H , Kabra P M , Marton L J
Published: January 2020

We describe a method for simultaneously measuring concentrations of coproporphyrin, zinc protoporphyrin IX, and protoporphyrin IX in whole blood by liquid chromatography, with use of reversed-phase ion-pair system, fluorometric detection, and internal standardization. Each analysis requires 10 microL of whole blood and 15 min total analysis time. Analytical recovery ranged from 84 to 92%, day-to-day precision (CV) from 5 to 12%. Uroporphyrin, though not studied in detail, can also be detected by this method.
Personal and familial factors in cholesterolemia: criteria for selection of a reference population.
Authors: Steinmetz J , Panek E , Siest G
Published: January 2020

We studied factors affecting cholesterolemia in a presumably healthy population of 23 300 subjects, ages 20 to 59 years. Multiple-contingency tables were established, to quantify the information obtained by means of a factorial correspondence analysis. The relations between values for cholesterol and those for triglycerides, uric acid, and overweight were constant for all ages and both sexes. Cholesterolemia paralleled alcohol and tobacco consumption and arterial blood pressure. Use of oral contraceptives did not influence cholesterol values. We classified variation factors according to the statistical method of segmentation, by sex and age. This classification permitted us to establish criteria for excluding subjects from a population sampled with the aim of producing reference values for plasma cholesterol. The values of cholesterol for the 50th percentile were 5.40 mmol/L for men 20 to 39 years old and 5.79 mmol/L for those older than 40. For women, the 50th percentile values increased from 5.34 mmol/L between ages 20 to 39 to 5.92 mmol/L for ages 40 to 49 and to 6.51 mmol/L after 50.
Rate of decrease of glutamyltransferase and acid phosphatase activities in the human vagina after coitus.
Authors: Gohara W F
Published: January 2020

I studied the rate at which gamma-glutamyltransferase (EC 2.3.2.2) and acid phosphatase (EC 3.1.3.2) activities decrease in the healthy human vagina after coitus. Specimens from the coital and non-coital vagina, and from the rectum and buccal cavity, and pre-ejaculate lubricating fluid were also assayed for both enzymes. Prostatic acid phosphatase was determined with use of two substrates: thymolphthalein monophosphate and alpha-naphthyl phosphate (tartrate-inhibitable fraction). Glutamyltransferase was assayed with gamma-glutamyl-p-nitroanilide as substrate. All non-coital specimens were negative for glutamyltransferase activity; the activity of acid phosphatase varied with type of substrate and type of specimen. The equation y = a + (b/x) describes the decline in activity (y) of either acid phosphatase or glutamyltransferase in the vagina of healthy women post-coitally with time (x).
Amniotic fluid phosphatidylglycerol and phosphatidylinositol separated by stepwise-development thin-layer chromatography.
Authors: Mitnick M , DeMarco B , Gibbons J M
Published: January 2020

We describe a stepwise-development thin-layer-chromatographic technique for separating phosphatidylglycerol and phosphatidylinositol in samples of amniotic fluid. Plates are prepared from silica gel G slurried in a 50 g/L ammonium sulfate solution. Phospholipid phosphorus determination is not needed. Phospholipid phosphorus determination is not needed. Phosphatidylglycerol and phosphatidylinositol, measured densitometrically, are expressed as ratios to the sphingomyelin present. These ratios are correlated with the lecithin/sphingomyelin ratio and age of gestation in normal and abnormal pregnancies.
Simultaneous liquid-chromatographic analysis for 4-hydroxy-3-methoxymandelic acid and 4-hydroxy-3-methoxyphenylacetic acid in urine.
Authors: Soldin S J , Hill J G
Published: January 2020

We describe a rapid, reliable “high-performance" liquid-chromatographic method of simultaneously analyzing for 4-hydroxy-3-methoxymandelic acid (I) and 4-hydroxy-3-methoxyphenylacetic acid (II) in urine. Paired-ion chromatography and amperometric detection are used in the method. A 5-mL aliquot of urine is adjusted to pH 6.1 and subjected to anion-exchange chromatography (Dowex AG 1-X4, 1.8 X 0.7 cm column). The two analytes are eluted from the column with 10 mL of 3 mol/L sodium chloride, and 2 microL of the eluate, injected directly into the liquid chromatograph, is chromatographed at 40 degrees C. This column contains mu Bondapak C18, and the mobile phase is 100 mmol/L potassium phosphate buffer, pH 6.7, containing 0.5 mmol of tetrabutylammonium phosphate per liter. Detector sensitivity is 50 nA full scale. Analytical recoveries of I and II are 80--84% and 48--49%, respectively; the coefficients of variation for various concentrations in urine are about 10%.
A lyophilized hemoglobin control prepared from stroma-free hemolysates.
Authors: Bonderman D P , Proksch G J , Haskins S
Published: January 2020

We prepared a stable lyophilized hemoglobin control from human erythrocytes by removing stroma with calcium and Ficoll. Addition of polyhydroxy compounds enhanced reconstitution and stability. The lyophilized product was stable during one year of use in a service laboratory. Accelerated aging studies demonstrated the potential of up to two years of stability, with methemoglobin increasing at a projected rate of approximately 6% per year. Reconstituted, the control gave reproducible values for at least five days when refrigerated.
Two-hour Sephadex column method for assay of unconjugated estriol in serum.
Authors: Haigh W G , Hofman L F , Barron E J
Published: January 2020

The column method of Christner and Fetter (Steroids 24: 327, 1974) has been modified to give a simple, rapid assay for unconjugated estriol in serum. Estriol is isolated from serum by being retained on a Sephadex column, while estriol conjugates and serum proteins are eluted. The sample and labeled estriol compete for antibody on the column. Antibody is eluted, removing proportional amounts of sample and labeled estriol. Our modifications include using stable serum-based standards, shortening the incubation to 10 min, complete removal of conjugates, and regeneration of the columns so that they can be used repeatedly. The assay, which can be completed in 2 h, has a mid-range interassay CV of 8.2%.
Improved electrophoretic separation of creatine kinase isoenzymes.
Authors: Burlina A
Published: January 2020

Creatine kinase isoenzymes are separated electrophoretically on cellulose acetate, with use of an improved procedure for reactivation and visualization of enzymic activity. N-Acetyl cysteine is used as the reactivator and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide for visualization in a tetrazolium-coupled system. This test, both practical and reliable, is a suitable alternative to chromatographic or immunochemical assay. The method allows: (a) detection of the MB isoenzyme on the basis of its electrophoretic migration, (b) confirmation of results obtained with other methods, particularly by immunoinhibition, and (c) detection of atypical bands of possible diagnostic significance in addition to the recognized fractions.
Automated multiple flow-injection analysis in clinical chemistry: determination of albumin with bromcresol green.
Authors: Renoe B W , Stewart K K , Beecher G R , Wills M R , Savory J
Published: January 2020

We describe an adaptation of automated multiple flow-injection analysis instrumentation to an analysis for albumin in serum. The bromcresol green reaction was used to test the utility of the system. The approach yielded albumin results with excellent sensitivity, no measurable carryover, a relative standard deviation of less than 1%, good correlations with published procedures, and no measurable interferences. The simplicity and flexibility of the instrumentation and its performance integrity, as indicated by the analytical results, make this a viable clinical chemical tool.
False-negative results for urinary phenothiazines and imipramine in Forrest's qualitative assays.
Authors: James G P , DJang M H , Hamilton H H
Published: January 2020

When a series of patients' urine samples supplemented in vitro with chlorpromazine or imipramine was assayed with the Forrest qualitative assays, we observed an occasional false-negative result, which we found was attributable to interference by ascorbic acid. It interferes with the reagent, not with the analytes, in both assays. We easily eliminated this interference with the phenothiazine test by using an anion-exchange resin. Eliminating the interference with the assay for imipramine, however, is more difficult; false-negative results can be obtained even after ion-exchange chromatography if the imipramine concentration is less than 50 mg/L.
Acid phosphatase in Gaucher's disease.
Authors: Robinson D B , Glew R H
Published: January 2020

Increased acid phosphatase activity in the serum and tissues of patients with Gaucher's disease has now been recognized for two decades, but as yet no relation has been established between the enzyme and the etiology and progress of the disease. Here, we review results obtained by various investigators, ranging from a consideration of the methods used for the evaluation of serum acid phosphatase in Gaucher's disease to the most recent findings regarding the purification and characterization of two acid phosphatase isoenzymes from the spleen from patients with Gaucher's disease. We also discuss the intracellular location of tissue acid phosphatase in patients with Gaucher's disease and its contribution to the increased activity in serum.
Hemoglobin determined in 15 microL of whole blood by "front-face" fluorometry.
Authors: Blumberg W E , Doleiden F H , Lamola A A
Published: January 2020

We describe the rapid, inexpensive fluorometry of hemoglobin in undiluted whole blood. The procedure consists only of adding a standard quantity of a fluorescent dye to a measured volume (approximately 15 microL) of blood, together with some solubilizing detergent. The assay is based on the attenuation of the dye's fluorescence (excited within the region 400—440 nm) that results from the competitive absorption of exciting light by the hemoglobin present—the "inner filter effect." The wavelength that one can use is optional and will determine which dyes can be used. Measurements are made with the hematofluorometer, a "front-face" filter fluorometer (Blumberg et al., J. Lab. Clin. Med. 89: 712—723, 1977). We demonstrate the validity of the method for two dyes, rhodamine B and fluorescein dibutyrate, which we used with hematofluorometers that were designed to determine blood zinc protoporphyrin and bilirubin, respectively. Our method exhibited a standard error of about 4 g of hemoglobin per liter vs the comparison method (Coulter Counter method, for which the CV is 1.2%). The CV is about 3%. The method seems appropriate for "field" use (i.e., use outside the laboratory) in anemia-screening programs.
Immunological and biochemical evidence for identity of tartrate-resistant isoenzymes of acid phosphatases from human serum and tissues.
Authors: Lam K W , Lee P , Li C Y , Yam L T
Published: January 2020

We purified acid phosphatase isoenzyme 5b from a human spleen affected by leukemic reticuloendotheliosis and used it to produce a specific antiserum. The antiserum was used to show complete immunological identity among isoenzymes 5a and 5b in human serum, and 5b isolated from a giant-cell bone tumor and from the spleen of a case of Hodgkin's disease. Acid phosphatase 5b in a giant-cell bone tumor was isolated for biochemical characterization. Its pH optimum and substrate specificity were very similar to those of isoenzyme 5b from human spleen.
Prostate-specific acid phosphatase: re-evaluation of radioimmunoassay in diagnosing prostatic disease.
Authors: Griffiths J C
Published: January 2020

The availability of a radioimmunoassay for prostate-specific acid phosphatase has allowed a correlative study between this technique and conventional colorimetric assays in the four clinical stages of prostatic adenocarcinoma. Results of such a study show an increased diagnostic sensitivity of the radioimmunoassay in all stages, but in 14% of Stage IV adenocarcinomas there was no increase in prostatic acid phosphatase above the ranges ordinarily expected for all methods. In cases of benign prostatic hyperplasia, there was an increase associated with in vivo tissue cytolysis, comparable to Stage II and III adenocarcinoma. The sensitivity of the test in Stage I is still low, but testing for combinations of tumor markers might increase the diagnostic yield. Conversely, a different clinical approach might be to establish baseline values in the "at-risk" patient, followed by regular determinations of prostate-specific acid phosphatase activity. Increases in activity within the normal expected range may be interpreted by the clinician as a herald of disease.
Gas-chromatographic analysis for phencyclidine in plasma, with use of a nitrogen detector.
Authors: Bailey D N , Guba J J
Published: January 2020

We describe a reliable gas-chromatographic analysis for unchanged phencyclidine in human plasma, with use of a nitrogen detector. The assay is sufficiently sensitive to permit measurement of as little as 5 microgram of the drug per liter, in 2 mL of plasma. Phencyclidine is extracted from plasma at pH 10.5 into hexane/iso-amyl alcohol containing meperidine as the internal standard, back-extracted into dilute HCl, and re-extracted into hexane/iso-amyl alcohol after alkalinization of the HCl. The coefficients of variation for the analysis at respective concentrations of 100 and 200 microgram/L are: within-run 4.0% and 3.4%; between-run, 2.8% and 5.2%. This procedure, used in our laboratory for more than one year, has been applied to plasma from numerous individuals with nonfatal phencyclidine intoxication. Some representative examples are given.
Further heterogeneity demonstrated for serum creatine kinase isoenzyme MM.
Authors: Chapelle J P , Heusghem C
Published: January 2020

Serum creatine kinase (EC 2.1.3.2) isoenzyme MM was resolved by isoelectric focusing into a five-band pattern, a pattern that gradually changed after the onset of myocardial infarction. Similar changes were also demonstrated in patients undergoing coronary-bypass surgery. The evolution of two CK-MB sub-bands was studied in both cases. We found that three electrophoretic bands (CK-MM, pI 7.10; MM1, pI 6.88; MB1, pI 5.61) were predominant in patterns for sera collected during the early phase of myocardial infarction, but rapidly disappeared during the following hours, whereas bands of increased electrophoretic mobility (MM2, pI 6.70; MM3, pI 6.45; MM4, pI 6.25; MB2, pI 5.34) gradually increased. MM3 was always the major band at the end of the observation period in acute myocardial infarction (mean, 61.4% of total creatine kinase activity 36 h after the peak value for total creatine kinase in serum). The CK-MM bands were also present in the serum of patients without heart disease. Changes in the electrophoretic pattern were induced by a thermolabile factor in normal human serum, which transformed the muscular or myocardial MM and MM1 bands after their release into the blood stream.
An interlaboratory study of the determination of digoxin by immunoassay.
Authors: Fast D M , Hannon W H , Burtis C A , Bayse D D
Published: January 2020

We conducted a voluntary survey of laboratories and manufacturers to assess the current quality of analytical assays for serum digoxin. More than 300 clinical laboratories and 18 manufacturers responded, giving data on methods, instruments, computational procedures, and results for five survey samples. We sorted the analytical data to provide statistical information on the grand mean values separately for manufacturers and clinical laboratories, the frequency distribution of all reported values, and the mean values by method of interpolation and algorithms used for linear transformation. There was no statistical difference (alpha = 0.05) between the means for each specimen as determined by the kit manufacturers as a group and the clinical laboratories as a group.
Nonspecific binding as a source of error in thyrotropin radioimmunoassay with polyethylene glycol as separating agent.
Authors: Chen I W , Heminger L , Maxon H R , Tsay J Y
Published: January 2020

We investigated the effects of nonspecific binding on thyrotropin values obtained by radioimmunoassay in which polyethylene glycol is used as precipitant. Differences in nonspecific binding among individual samples were significant (F-test, p less than 0.001, range 5.5 to 14.1%). Non-specific binding and total serum protein were directly correlated (r = 0.472, n = 59; p less than 0.001). Nonspecific binding increased with increasing concentrations of globulins but showed no relation to albumin concentration. If globulin concentration was less than 15 g/L, precipitation of the antigen—antibody complex by polyethylene glycol was incomplete. The mean value for thyrotropin in sera from 67 healthy subjects was 2.7 (SD 0.3) milli-international units per liter (milli-int. unit/L) without individual serum nonspecific binding correction, significantly (p less than 0.005) higher than that with nonspecific binding correction (1.6, SD 0.1, milli-int. unit/L). Evidently, inter-sample variations in nonspecific binding may cause significant errors under these conditions, which can be minimized by taking into account the individual nonspecific binding of each serum sample.
Continuous-flow (Autoanalyzer I) analysis for plasma thiocyanate as an index to tobacco smoking.
Authors: Dalferes E R , Webber L S , Radhakrishnamurthy B , Berenson G S
Published: January 2020

We describe a procedure for determining thiocyanate in plasma with a Technicon AutoAnalyzer I, modified with a 50-mm tubular flow cell to increase the sensitivity of thiocyanate detection. The procedure is suitable for distinguishing cigarette smokers from non-smokers, the mean for smokers being 151 (SD 43) micromol/L and for non-smokers 62 (SD 19) micromol/L.
Binding of IgG and other proteins to microfilters.
Authors: Walsh R L , Coles M E
Published: January 2020

We evaluated 10 microfilters for their ability to filter diluted sera without removing immunoglobulins (Ig) G, A, and M, albumin, and transferrin. In general, filters containing cellulose nitrate remove IgG from solution, the amount adsorbed being proportional to the IgG concentration in the solution. With some sera we noted IgA and IgM adsorption to cellulose-nitrate-containing filters, but there was no significant adsorption of albumin or transferrin to any of the filters. We also found that cellulose-nitrate filters adsorbed IgG from antiserum, with consequent loss of titre as seen in a nephelometric assay. Adsorption of IgG was not seen if the filters were prewashed with polyethylene glycol or if the antisera contained polyethylene glycol. With a sufficiently large antibody excess in the nephelometric assay, this loss of titre through filtration becomes undetectable.
Semiautomated homogeneous enzyme immunoassay of total serum thyroxine with a kinetic analyzer.
Authors: Bhatia H
Published: January 2020

A new semiautomatic procedure for determination of total serum thyroxine was adapted to a kinetic analyzer, LKB 2086 Mark II. The ABA thyroxine assay kit was used, and although the assay procedure was modified, the advantage of small reagent volumes, short measuring times, and automation were retained. The results were analyzed off-line with a programmable desk-top calculator. The method has a precision of 7% (CV) and a sensitivity of 8 nmol/L. Values in sera from 64 patients analyzed by enzyme immunoassay and by radioimmunoassay correlated well (r = 0.975). One kit contains enough reagents for 500 assays, and an operator could do 25 samples (i.e., 64 assays) in about 4 h.
Potential sources of errors in cation-exchange chromatographic measurement of plasma taurine.
Authors: Connolly B M , Goodman H O
Published: January 2020

We examined the potential sources of error in automated cation-exchange chromatographic quantitation of plasma taurine, both in sample preparation and in the analysis. Principal sources of error include: use of serum instead of plasma, which produces gross overestimates; use of tripotassium ethylenediaminetetraacetate (EDTA) as anticoagulant in systems involving ninhydrin detection (a ninhydrin-positive contaminant of EDTA emerges coincident with taurine); contamination with platelets; and placing volumes exceeding 20 microL on the cartridge used in the Technicon TSM Amino Acid Analyzer. We arrived at a simple technique in which we use EDTA as anticoagulant, micropore filtration to produce platelet-free plasma, and o-phthalaldehyde as the detection reagent for the sensitivity required to measure accurately the low concentration of taurine in plasma.
A radioimmunoassay for 1,25-dihydroxycholecalciferol.
Authors: Bouillon R , De Moor P , Baggiolini E G , Uskokovic M R
Published: January 2020

We describe a radioimmunoassay for 1,25-dihydroxycholecalciferol in human serum. We raised antisera in rabbits to 1,25-dihydroxycholecalciferol-3-hemisuccinate coupled to bovine serum albumin, and obtained sensitive, high-titer antibodies. These antibodies had a high affinity for 1,25-dihydroxycholecalciferol and cross reacted mainly with 25-hydroxycholecalciferol and 24,25-dihydroxycholecalciferol. Addition of 1 mL of normal rabbit serum per liter reduced this interference to 5 and 4%, respectively. However, these interfering steroids are present in large excess, so extensive purification of 1,25-dihydroxycholecalciferol from serum is necessary. The steroid was extracted with ethyl acetate/cyclohexane, purified on Sephadex LH-20, and then chromatographed on a column of silicic acid. The radioimmunoassay is sensitive to 5 pg/tube (3 ng/L of serum). The between-assay CV was 14%. The mean concentration of 1,25-dihydroxycholecalciferol in the serum of 54 healthy adults was 38 (SD 12) ng/L, with no sex-related difference. The assay was further validated by the finding of low or undetectable concentrations in patients with chronic renal failure and of increased concentrations in the serum of patients with primary hyperparathyroidism. In comparison with previously described methods, the major advantage of the present assay is the use of stable gamma-globulins, which are available in large amounts, as binding protein.
Serum high-density lipoprotein cholesterol concentrations in hypo- and hyperthyroidism.
Authors: Scottolini A G , Bhagavan N V , Oshiro T H , Abe S Y
Published: January 2020

We studied alterations in the concentration of high-density lipoprotein cholesterol and of other lipid categories (total cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, and triglycerides) in serum in hypo- and hyperthyroid states, and compared these findings with those of a control group. In the latter group the lipids showed an age-related increase in concentration but with a decrease in the eighth decade in all categories. In untreated hypo- and hyperthyroid subjects, all of the lipid values differed significantly from those of the controls but promptly returned to normal values upon treatment. In hypothyroid patients who are prone to develop coronary heart disease, the concentrations of high-density lipoprotein cholesterol were high, suggesting protection against heart disease, while the ratio to total cholesterol indicated the contrary. The exact opposite of these relationships was seen in hyperthyroid disorders. This apparent paradox suggests that the low-density lipoprotein cholesterol in serum, with its established atherogenic effect, should be given at least equal, if not more, weight than the concentration of high-density lipoprotein cholesterol in serum, with its alleged protective effect.
Commercially-supplied binders for plasma cobalamin (vitamin B12), analysis--"purified" intrinsic factor, “cobinamide"-blocked R-protein binder, and non-purified intrinsic factor-R-protein binder--compared to microbiological assay.
Authors: Kubasik N P , Ricotta M , Sine H E
Published: January 2020

Recent evidence (Kolhouse et al., N. Engl. J. Med. 299: 785–792, 1978) demonstrates that commercial cobalamin (Vitamin B12) radioassay kits contain nonspecific R-protein binding agents that can give falsely normal results in patients who are actually cobalamin deficient. We tested three kits: with “purified” intrinsic factor as the binder, with intrinsic factor and the nonspecific R-protein sites blocked with “cobinamide,” and non-purified intrinsic factor-R-protein binder. Results with use of the first two compared well with those by a microbiological assay (Lactobacillus leichmannii) and are in harmony with clinical impressions.
Reference values for cerebrospinal fluid glutamine concentration in infants.
Authors: Boeckx R L , Iosefsohn M , Hicks J M
Published: January 2020

We measured cerebrospinal fluid glutamine concentration in a reference group of 85 newborn to 30-month-old infants. All of the spinal taps were performed for the diagnosis of illnesses unrelated to hyperammonemia or hepatic encephalopathy. We also analyzed samples from patients with meningitis or cerebral hemorrhage, or who were receiving total parenteral nutrition. The mean glutamine concentration in cerebrospinal fluid in the reference group was somewhat lower than values reported for older children and adults. Values were significantly higher in patients with meningitis or cerebral hemorrhage and in those infants receiving total parenteral nutrition.
Performance of a radiometer transcutaneous oxygen monitor in a neonatal-intensive-care unit.
Authors: Graham G , Kenny M A
Published: January 2020

We evaluated the performance of the Radiometer TCM-1 Transcutaneous Oxygen Monitor in a Class III neonatal-intensive-care unit during an 11-month clinical trial (in excess of 4000 h) in which we monitored 115 infants ranging in gestational age from 25 to 43 weeks and in birthweight from 595 to 4220 g. In vitro transcutaneous partial pressure of oxygen (ptcO2) measurements were accurate within 1% of the theoretical value and precise (1.4% CV at 156 mmHg) at 44 degrees C. Determinations at other temperature were less accurate except in rare instances when specific patient-associated ptcO2/paO2 bias was identified. In vitro comparison of ptcO2 (y) and arterial partial pressure of oxygen (paO2) (x) measurements agreed well (y = 0.90x + 6.9, r = 0.94) except when infants were less than 24 h old. In this latter group the ptcO2/paO2 ratio usually exceeded 1.0 and fluctuated unpredictably. ptcO2 measurements on infants less than 24 h old had to be interpreted cautiously. In general, the ptcO2 and paO2 measurements agreed sufficiently well for the physicians to use them as the basis for directing patient care.
Interference of imferon in colorimetric assays for iron.
Authors: Huisman W
Published: January 2020

Imferon (Merrell-National), an iron-dextran complex, is widely used in patients with iron deficiency. It is present in the circulation in appreciable amounts for two to three weeks after administration and interferes with all tested colorimetric iron assays, both with and without deproteinization. The amount of the plasma Imferon iron interference depends primarily on the choice of reductant. With dithionite it is essentially 100%. In the presence of ascorbic acid and hydroxylamine, the interference depends also on assay conditions, especially temperature, but also incubation time and pH. The minimum interference in a homogeneous assay was about 3%. The relative amount of interference from hemoglobin iron under the various assay conditions is different from that of Imferon iron. In the presence of a reducing agent, the dextran-iron complex decomposes--instantaneously with dithionite, and gradually with sulfite, ascorbic acid, and hydroxylamine. The freed iron becomes dialyzable, can react with bathophenanthroline, and elutes on a Sephadex G-50 or G-15 column in the same fractions as an ammonium ferrous sulfate.
Gas-chromatographic determination of disopyramide and its mono-N-dealkylated metabolite in serum with use of a nitrogen-selective detector.
Authors: Bredesen J E
Published: January 2020

I describe a rapid, simple routine gas-liquid chromatographic method for simultaneous isothermal quantitation of disopyramide and its mono-N-dealkylated metabolite. The method involves one extraction step with dichloromethane, derivatization of the metabolite, and gas chromatography with an OV-17 liquid phase. Standard curves were linear over the concentration range tested (0.1-25 mg/L) and the maximum coefficient of variation was 9.2%. Quantitation of both disopyramide and its mono-N-dealkylated metabolite with the present method is less time-consuming than are gas-chromatographic methods previously described.
Fluorometric quantitation of glutamine in cerebrospinal fluid.
Authors: Liu T Z , Khayam-Bashi H
Published: January 2020

We describe a rapid, relatively simple-procedure for fluorometry of glutamine in cerebrospinal fluid. Glutamine is de-aminated with diluted sulfuric acid at 100 °C. The ammonia liberated is then reacted with a buffered o-phthalaldehyde—mercaptoethanol solution, pH 7.4, to form a fluorochrome. Fluorescence is linearly related to the concentration of glutamine from 0.10 to 0.60 g/L (0.68 to 4.10 mmol/l). To prevent interference by endogenous ammonia, each specimen was corrected for its own background fluorescence. The mean analytical recovery was 99.8%. Within-day variation (CV) for pooled, enriched cerebrospinal fluid controls at 0.33 g/L (2.22 mmol/L) and 0.53 g/L (3.63 mmol/L) were 2.2 and 5.1%. Day-to-day variation (CV) for the same controls was 4.4 and 4.8%, respectively. Data obtained by our method correlate excellently (r = 0.980) with those by an established procedure based on the Berthelot (phenol—hypochlorite) reaction.
Plasma methotrexate as determined by liquid chromatography, enzyme-inhibition assay, and radioimmunoassay after high-dose infusion.
Authors: Howell S K , Wang Y M , Hosoya R , Sutow W W
Published: January 2020

Three techniques for measuring methotrexate show various cross reactivities with methotrexate-related compounds: “high-pressure” liquid chromatography, by principle, is virtually specific for methotrexate; the enzyme-inhibition assay quantitates methotrexate, methotrexate diglutamate, and methotrexate triglutamate equally well, but has a 10% cross reactivity with 4-amino-4-deoxy-N10-methylpteroic acid and 1% with 7-hydroxymethotrexate; radioimmunoassay shows an equal cross reactivity with methotrexate, 4-amino-4-deoxy-N10-methylpteroic acid, methotrexate diglutamate and triglutamate, and a 5 to 10% cross reactivity with 7-hydroxymethotrexate. Radioimmunoassay almost always yielded the highest values for methotrexate, followed by enzyme-inhibition assay then liquid chromatography. The presence of two methotrexate-related compounds, 7-hydroxymethotrexate and 4-amino-4-deoxy-N10-methylpteroic acid, was confirmed in human urine samples and quantitated in patients’ plasma by liquid chromatography, the respective maximum plasma concentrations being 250 and 16 mumol/L. Materials cross reacting with methotrexate in radioimmunoassay of chromatographic fractions from plasma were also noted in fractions corresponding to methotrexate diglutamate and triglutamate peaks, in quantities estimated to be 47 and 30 nmol/L methotrexate equivalents, respectively. 7-Hydroxymethotrexate is eliminated more slowly than methotrexate and its production increases with dosages of methotrexate.
Variability in the adsorption properties of microtitre plates used as solid supports in enzyme immunoassay.
Authors: Kricka L J , Carter T J , Burt S M , Kennedy J H , Holder R L , Halliday M I , Telford M E , Wisdom G B
Published: January 2020

We evaluated the variability in the amount of protein adsorbed onto the surface of individual wells of an assortment of microtitre plates by use of procedures involving enzyme-protein conjugates. Coefficients of variation in adsorbed protein ranged from 5.2 to 29.5%. Microtitre plates show a distinct “edge effect”; wells at the edges of a plate adsorb more protein than those in the interior, which markedly affects results from immunoassays involving such plates. In a sandwich enzyme immunoassay the results for an individual sample varied by +/− 18%; in a competitive assay, values read from different calibration curves in the same plate varied by +/− 11%. Scanning electron microscopy and birefringence studies demonstrated no marked physical differences between individual wells on a plate. The variability in the amount of protein adsorbed onto the surface of individual wells on the same microtitre plate seriously affects the reliability and interpretation of results of immunoassays in which such plates are used as solid supports.
The contribution of assays for lymphocyte capping and creatine kinase to detection of the Becker-type dystrophy trait.
Authors: Goldsmith B M , Gruemer H D , Hawley R J , Pickard N A , Verrill H L , Nance W E , Miller G , Crawford R G
Published: January 2020

Members of three unrelated families with the mild Becker type of muscular dystrophy were subjected to lymphocyte capping tests and measurements of serum creatine kinase activity. Both tests correctly identified all nine affected males, but only the capping test was abnormal in seven of eight obligate carriers. The number of capped cells in carriers and affected persons with the Becker-type dystrophy was generally intermediate between those observed for individuals with the Duchenne trait and normal controls, thus potentially aiding in the differential diagnosis between the two myopathies. The lack of sensitivity of measurements of serum creatine kinase activity in identifying carriers is further complicated by the difficulty of establishing reliable reference intervals for this enzyme in 204 healthy controls. Detailed directions for the performance of the capping test are presented.
Isoenzymes of creatine kinase in extracts of various parts and regions of the human central nervous system.
Authors: Petronia R R , Maas A H , van Veelen C W , Staal G E
Published: January 2020

The distribution of isoenzymes of creatine kinase (EC 2.7.3.2.) was investigated by agarose gel electrophoresis of extracts of selected parts and regions of the human central nervous system. Besides the major brain isoenzyme BB, we demonstrated the presence of three other creatine kinase isoenzyme forms. The distribution of creatine kinase isoenzymes depending strongly on the region from which the biopsy was taken. We found substantial amounts of the MB isoenzyme in extracts of the dura from the cauda equina of the two adults examined.
Simplified approach to confidence limited in radioimmunassay.
Authors: Baxter R C
Published: January 2020

A simple method of calculating confidence limits for radioimmunoassay data is presented. The method involves the use of the within-assay variation in dose estimate of three routine quality-control specimens, measured in repeated assays, to estimate the confidence limits for results on unknown samples. Results for control specimens are combined by calculating the unique quadratic curve fitting a graph of within-assay standard deviation vs mean value for each control. This method requires no special data accumulation or advanced computing equipment. For cortisol, lutropin, and thyroxine radioimmunoassays, confidence limits calculated in this way have been compared with those calculated from the variance of the response variable “B/B0” in repeated standard curves. Both methods agree well with actual limits observed when plasma pools containing a wide range of hormone concentrations are assayed repeatedly.
Lamellar body phospholipid content of amniotic fluid and L/S ratio compared in assessing fetal lung maturity.
Authors: Duck-Chong C G , Gupta J M , Storey G N , Houghton C R
Published: January 2020

A micro-method has been devised for isolating a lung-derived membranous fraction from human amniotic fluid. The phospholipid content of this fraction, known as lamellar body phospholipid, provides an indication of fetal lung maturity (Ann. Clin. Biochem 16: 191, 1979). This method has now been applied to 479 samples of amniotic fluid from 330 pregnancies. The lecithin/sphingomyelin ratio has also been determined for each of the samples by the routine method currently in use in the hospitals providing the samples. Hyaline membrane disease was associated with a low concentration of lamellar body phospholipid (< 35 mg/L) in all eight cases encountered in this study. In contrast, in 182 of the 185 cases where the lamellar body content of the amniotic fluid, collected within two days of delivery, exceeded 35 mg/L, the infants were free from serious respiratory problems. Data are presented which suggests that the lecithin/sphingomyelin ratio falsely indicated lung immaturity in many cases, amounting to 44% or more of all values indicating immaturity that were reported.
Carcinoembryonic antigen assayed by column chromatography on polyacrylamide gel.
Authors: Weissman E B
Published: January 2020

I evaluated a commercially available polyacrylamide column (Clinetics Corp.) for use in assaying for carcinoembryonic antigen. The procedure eliminates the need for dialysis and 50 samples, assayed in duplicate, may be completed in 5 h. In general, results by this technique are 1.0 microgram/L (range 0.5-2.0) lower than by the conventional dialysis method (r = 0.9876). Sensitivity approximates 0.5 microgram/L. Within-day precision for two pools of patients’ plasma (n = 10) was mean = 2.29 (SEM 0.05) microgram/L with CV = 6.55% and mean = 10.61 (SEM 0.10) microgram/L with CV = 2.92%, respectively; between-day precision (n = 6) was mean = 3.90 (SEM 0.16) microgram/L with CV = 10.0% and mean = 10.1 (SEM 0.37) microgram/L, CV = 8.91%, respectively. The precentage analytical recovery of added carcinoembryonic antigen was about 80% at concentrations of approximately 8 and 12 microgram/L, 73% at 18 microgram/L.
The coefficient of analysis, a new figure of merit for laboratory performance.
Authors: Louderback A L , Szatkowski P R
Published: January 2020

A simple statistic has been developed to determine a figure of merit for overall laboratory performance. This simple statistic, the coefficient of analysis, relates for the first time both the imprecision and the inaccuracy of a laboratory analysis to a single value that clinical chemists will easily understand. In the derivation of the coefficient of analysis, we also define two secondary statistics: the coefficient of bias, which is mathematically similar to the CV and represents the inaccuracy of an analysis, and the coefficient of accuracy, which is mathematically represented as 100 minus the coefficient of bias and is a measure of the accuracy of the analysis.
Influence of Posture on Free Calcium and Related Variables
Authors: Renoe Brian W , McDonald Jay M , Ladenson Jack H
Published: January 2020

Vol. 25

p 1766: Second paragraph, line four, the reference numbers cited should be (5-11); numbers of all subsequent citations above 10 in text should be increased by one, to correspond with the list of references.

p 1828: In Figure 2, the label on the ordinate is not clear. It reads “counts/10 s × 10−3.”

p 1930: Under “Determination of Concentrations in Human Plasma,” the injection of dihydroergotamine should be 0.5 mL of a 1 g/L solution.

p 1931: Nine to 12 determinations of binding in the absence of nonradioactive standard were also used to construct the standard curves.

p 1932: In the paragraph preceding Results and in the caption to Figure 3, the amount of compound 2 is 0.5 mg, not 1 mg.

p 2020: In the preparation of phosphate buffer, the second sentence should read: “Dissolve 2.84 g of sodium diphosphate in 100 mL of de-ionized water (solution 2).”

p 2021: In the section on extraction of serum under Procedures, the 10 µL of internal standard and 200 µL of sample should be added to 200 µL of phosphate buffer.

Vol. 26

p99: In the caption for Figure 3A, read “r = 0.99,” not “r = 0.09.”

p. 176: The sample volume referred to in the fourth paragraph of column three should be 0.15 µL, not “150 mL.”

p 193: Add to reference list:

8. Goutte-Coussieu, C., Habrioux, G., Eichenberger, D., and Jayle, M. F., Rapid fluorometry of estrogens in nonpregnancy urine, with use of chloroform extraction and purification by anion-exchange chromatography. Clin. Chem. 25, 230 (1979).

9. Jarrige, P., Purification et propriétés des sulfatases du suc d’Helix pomatia. Bull. Soc. Chim. Biol. (Paris) 7-8,761 (1963).

10. Ittrich, G., Untersuchungen über Extraktion des roten Kober-Farbstoffs durch organische Lösungsmittel zur Ostrogenbestimmung im Harn. Acta Endocrinol. (Copenhagen) 35, 34 (1960).

11. Adessi, G., Lallier, J. C., Goutte-Coussieu, C., and Jayle, M. F., Méthode de dosage automatique par spectrofluorimétrie des estrogénes urinaires au cours et en dehors de la grossesse. Ann. Biol. Clin. 37, 89 (1979).

12. Schöller, R., Contrôle de Qualité en Hormonologie. I.-Stéroides Urinaires. Editions Sepe, Paris-Fresnes, 1976, p 51.

p. 354: In Table 1, last line, columns 2 and 4, substitute “0.12” for “0.16.”
Measurement of tricyclic antidepressants. Part II. Applications of methodology.
Authors: Scoggins B A , Maguire K P , Norman T R , Burrows G D
Published: January 2020

This review, together with Part 1 (Clin. Chem. 26: 5-17, 1980), summarizes progress in measurement of tricyclic antidepressants in biological fluids and the application of the methodology to clinical practice. For many of the older drugs and for all of the new-generation antidepressants, further studies are required to delineate the precise relationship between plasma concentration and clinical response in well-defined diagnostic groups. For new drugs, rigorous evaluation of a method of measurement is required before it is applied to clinical studies. Assessment of drug interactions, inter-patient variability in plasma concentrations, and determination of the plasma concentrations required for therapeutic response all depend almost entirely on the quality of the assay methodology.
Improved serum-initiated aspartate aminotransferase assay by inhibition of lactate dehydrogenase with oxamate.
Authors: Lustig V , Redman L W
Published: January 2020

We describe a serum-inititated aspartate aminotransferase (EC 2.6.1.1) assay that obviates the need for added lactate dehydrogenase (EC 1.1.1.27) in the reagent system. Interference from the oxidation of NADH by endogeneous lactate dehydrogenase is eliminated by adding sodium oxamate, a competitive inhibitor of the enzyme. The advantages of oxamate inhibition over lactate dehydrogenase addition are a shorter preincubation period, an increase in the linear range from less than 600 to more than 1400 U/L, no interference from above-normal concentrations of ketoacids, and elimination of bias between serum-initiated and the standard oxoglutarate-initiated assays for aspartate aminotransferase.
Serum gastrins in Zollinger-Ellison syndrome: identification of localized disease.
Authors: Johnson J A , Fabri P J , Lott J A
Published: January 2020

We determined the relative concentrations of gastrin molecular species in serum samples from 21 patients with Zollinger-Ellison syndrome with localized gastrinoma (n = 11) or gastrinoma with hepatic metastases (n = 10). Gastrin molecular species were separated by gel-filtration chromatography and quantitated by radioimmunoassay with a gastrin antiserum produced in our laboratory. The percentage gastrin-17 of the total gastrin in the two groups differed significantly (nonparametric Wilcoxon rank test; p less than 0.01). Patients with the Zollinger-Ellison syndrome with apparently localized gastrinoma had a lower percentage of G- 17 (7.6%, SEM 1.6%) than did patients with gastrinoma with hepatic metastases (31.1%, SEM 6.1%). This procedure may be useful in the early classification of tumors in patients with Zollinger-Ellison syndrome.
DNA nucleotidylexotransferase of normal persons and leukemic patients.
Authors: Yasmineh W G , Smith B M , Bloomfield C D
Published: January 2020

We describe a relatively simple and rapid assay for DNA nucleotidylexotransferase (EC 2.7.7.31) activity in normal lymphocytes and leukemic cells from blood and (or) bone marrow of patients with various types of leukemia. We followed the method of Beutler and Kuhl (Am. J. Clin. Pathol. 70: 733, 1978) but separated the product of the reaction by precipitation on filter-paper disks instead of by centrifugation. Normal lymphocytes had a mean activity of 13.5 (SD = 9.21; range 3 to 35) pU/10(8) cells. Leukemic cells from the peripheral blood of patients with acute myelogenous leukemia had a mean activity slightly greater than normal (48 pU/10(8) cells); those from patients with acute lymphoblastic leukemia had a mean activity of 863 pU/10(8) cells, or 62-fold the normal mean. Similarly, cells from patients with chronic myelogenous leukemia in acute phase had a normal activity when the cell proliferation was myelogenous, but much higher activities when the cell proliferation was lymphoblastic. Cells from patients with chronic lymphocytic leukemia had normal activity. In leukemic patients, approximately similar results were obtained with cells isolated from bone marrow.