bluuebunny/crossref_metadata_2025_split huggingface dataset:
Salivary immunoreactive insulin: a new entry in clinical chemistry?
Authors: Marchetti P , Grossi C , Giannarelli R , Masoni A , Cristofani R , Giannecchini M , Navales R 
Published: January 2020

Abstract
The distribution of salivary immunoreactive insulin (S-IRI) and its relation to plasma insulin (P-IRI) and other clinical and metabolic variables were investigated in 93 nondiabetic subjects (60 males, 33 females, ages 11-70 y). S-IRI was measured by RIA, with monoiodinated insulin as labeled antigen and with standards consisting of serial dilutions in saliva of known amounts of native insulin. The sensitivity of the method was 12.1 pmol/L. The intra- and between-assay CVs were near 10%, and analytical recovery exceeded 93% for various insulin concentrations added to saliva. S-IRI, measured after overnight fast, showed a nonguassian distribution in males (skewness 1.18, kurtosis 1.41) and females (skewness 1.71, kurtosis 1.18); mean and median values were higher in males (14.3 and 12.1 nmol/min) than in females (12.1 and 7.15 nmol/min), but not significantly so. S-IRI was significantly correlated with P-IRI both in males (r = 0.75, P less than 0.0001) and females (r = 0.72, P less than 0.0001). These results, particularly the correlation between S-IRI and P-IRI, indicate the possibility of using S-IRI measurement in clinical practice.
Rapid determination of the hypoxanthine increase in ischemic exercise tests.
Authors: Bolhuis P A , Zwart R , Bär P R , de Visser M , van der Helm H J 
Published: January 2020

Abstract
After ischemic exercise tests, performed to detect glycogenoses or myoadenylate deaminase (EC 3.5.4.6) deficiency, the increases in serum lactate and ammonia usually are measured. Determination of hypoxanthine instead of ammonia can also be used to show myoadenylate deaminase deficiency, but HPLC of hypoxanthine is time-consuming. As a substitute, we developed an indirect enzymatic equilibrium method for hypoxanthine based on coupling the chromogenic system 3,5-dichloro-2-hydroxy-benzenesulfonic acid/4-aminophenazone with formation of hydrogen peroxide by xanthine oxidase (EC 1.1.3.22). The pH optimum is at 7.8 and the absorbance maximum at 510 nm. The calibration curve is linear from 0 to 100 mumol/L and the detection limit is 0.9 mumol/L. Analytical variability (CV) was 1.5% to 3.6% within-run, 4.5% to 8.5% between-run. The assay can be performed with a standard spectrophotometer or a centrifugal analyzer. The coefficient of correlation was 0.68 between hypoxanthine and ammonia increases in plasma from controls who performed the exercise test.
Amino acid concentrations in serum and aqueous humor from subjects with extreme myopia or senile cataract.
Authors: Wuu J A , Wen L Y , Chuang T Y , Chang G G 
Published: January 2020

Abstract
With an amino acid analyzer, we measured amino acids and related compounds in serum and aqueous humor from normal Chinese and some patients with extreme myopia or senile cataracts. Forty peaks were well resolved, and their areas were used to quantify each compound. In the myopic patients, glutamate, alpha-aminoadipate, and methionine concentrations in serum were 10-fold those in the normal subjects. Values for most of the other amino acids and related compounds were also higher in myopic patients' sera. In the cataract patients, concentrations of most of these compounds were lower in serum but higher in aqueous humor than for the normal subjects. Tryptophan was present in significant amounts in sera from the normal subjects, but was not detectable in the senile-cataract patients. The ratio of amino acid concentration in aqueous humor to that in the serum (Ch/Cs) was higher in the cataract patients than in normal subjects for almost all of the compounds we measured.
Age- and sex-specific pediatric reference intervals: study design and methods illustrated by measurement of serum proteins with the Behring LN Nephelometer.
Authors: Lockitch G , Halstead A C , Quigley G , MacCallum C 
Published: January 2020

Abstract
We analyzed blood from 450 healthy children and adolescents, ages one to 19 y, as well as term and preterm infants, to define age- and sex-specific reference intervals for numerous blood constituents. Reference intervals were derived by using nonparametric methods to determine the 0.025 and 0.975 fractiles. Ten serum proteins were measured with the Behring LN Nephelometer. Girls over 10 years of age had higher concentrations of ceruloplasmin and alpha 1-antitrypsin than other children had. There was no sex-related difference in reference intervals for the other proteins tested. Reference intervals are presented for immunoglobulins G, A, and M, complement fractions C3c and C4, ceruloplasmin, transferrin, alpha 1-antitrypsin, retinol-binding protein, and prealbumin (transthyretin).
The Abbott IMx automated benchtop immunochemistry analyzer system.
Authors: Fiore M , Mitchell J , Doan T , Nelson R , Winter G , Grandone C , Zeng K , Haraden R , Smith J , Harris K 
Published: January 2020

Abstract
We describe a new clinical laboratory instrument, the IMx, used to automate immunoassay testing in the clinical laboratory. The IMx incorporates a novel technology called Microparticle capture Enzyme ImmunoAssay (MEIA) for assays of high-molecular-mass analytes, and fluorescence polarization immunoassay (FPIA) for hapten assays. A front-surface fluorometer is used to quantify the enzymatic generation of fluorescent product at a rate proportional to the concentration of the analyte in an MEIA, and a fluorescence polarization optical system is used to quantify results in an FPIA. The microprocessor-based instrument uses a robotic arm with two degrees of freedom and a rotating carousel to process the samples for assay. One assay can be done on each of 24 patients' specimens in 30 to 40 min with "walk-away" automation. Calibration curves are stable for at least two weeks. Instrument control involves software-labeled "command keys," a numeric keypad, and an interactive display. Results are output to a thermal printer or computer interface.
Rapid immunochemical detection of fecal occult blood by use of a latex-agglutination test.
Authors: Väänänen P , Tenhunen R 
Published: January 2020

Abstract
A novel immunochemical test, "Hemolex," is characterized and compared with three guaiac tests: "Hemoccult" (Smith-Kline, U.S.A.), "Hemofec" (Boehringer Mannheim, F.R.G.), and "Fecatwin Sensitive" (Labsystems, Finland). We tested 191 stool specimens from patients, 144 from healthy persons. The sensitivity of Hemolex was 0.6 mL of blood per 100 g of stool. It reacts with neither animal hemoglobin nor human myoglobin, unlike the guaiac tests, nor does it react with the stool of healthy persons under no dietary restrictions, while the guaiac tests react variably. As a rule, Hemolex is insensitive to bleeding in the upper gastrointestinal tract, unlike the guaiac tests. However, Hemolex seems to be more sensitive to bleeding in the lower gastrointestinal canal than are the other tests, and we show it to be suitable for screening for occult blood originating there. It is unaffected by diet. It is simple to perform, requires no special equipment, and stool specimens, stored in the test diluent, are stable for testing for two weeks.
Decreased stability of triglycerides and increased free glycerol in serum from heparin-treated patients.
Authors: Hortin G L , Cole T G , Gibson D W , Kessler G 
Published: January 2020

Abstract
Triglycerides usually are stable in serum. However, for a few patients, we noted marked decreases in measured triglycerides when the same serum specimen was analyzed on successive days. This was found to be ascribable to intravenous administration of heparin. Measured triglyceride in serum of 11 patients being treated with heparin decreased 34% (SD 17%) in samples stored for one day at room temperature. Triglyceride values for sera from control patients remained unchanged. Increases in free glycerol corresponded to the observed decreased in triglycerides. Measurement of free glycerol thus provides a means of recognizing this problem.
Time-dependence of urinary neopterin, a marker of cellular immune activity.
Authors: Auzéby A , Bogdan A , Krosi Z , Touitou Y 
Published: January 2020

Abstract
Neopterin, a marker of cellular immune system activation, is produced by human macrophages after induction by interferon gamma (secreted by T-lymphocytes) and is eliminated mostly in urine. We have documented the circadian rhythm of urinary neopterin in five healthy young men (about 25 years old), using voidings collected during 48 h at fixed 4-h intervals. We repeated the experiment three times, one week apart. Neopterin was measured by high-performance liquid chromatography (HPLC). We clearly show a peak of the excretion of neopterin in the early morning (around 0630 hours +/- 2 h), with total variability (peak-trough difference) reaching 51%. Neopterin is commonly assayed in urinary fractions, so it is imperative to use urine specimens collected at the same time of day--e.g., the first morning urines--to avoid misinterpretation in follow-up of patients.
Determination of the antidepressant fluoxetine and its metabolite norfluoxetine in serum by reversed-phase HPLC with ultraviolet detection.
Authors: Orsulak P J , Kenney J T , Debus J R , Crowley G , Wittman P D 
Published: January 2020

Abstract
A procedure has been developed for measuring fluoxetine and its desmethyl metabolite, norfluoxetine, in serum by reversed-phase high-performance liquid chromatography (HPLC), with ultraviolet detection at 226 nm. Fluoxetine and norfluoxetine are isolated from serum by liquid-liquid extraction. They are then separated by HPLC and quantified, with reduced haloperidol as the internal standard. Fluoxetine, norfluoxetine, and the reduced haloperidol are separated from all interfering peaks in about 15 min. The standard curve is linear (r = 1.000) for both fluoxetine and norfluoxetine concentrations over the range of 25 to 800 micrograms/L. Between-run CVs for 60 and 200 micrograms/L controls (n = 8) were 6.8 and 4.1% for fluoxetine, and 8.8 and 6.2% for norfluoxetine, respectively. In a study of 24 patients with depression who were being treated with 20-60 mg of fluoxetine per day, fluoxetine and norfluoxetine concentrations in serum, measured during the last three weeks of treatment, were 47-469 micrograms/L and 52-446 micrograms/L, respectively.
Production of murine hybrid-hybridomas secreting bispecific monoclonal antibodies for use in urease-based immunoassays.
Authors: Takahashi M , Fuller S A 
Published: January 2020

Abstract
To produce bispecific antibodies (BiAbs) for enzyme immunoassay (EIA) to replace antibody-enzyme conjugates, we developed a panel of 8-azaguanine/ouabain-resistant anti-urease variant hybridoma cell lines for use in hybridoma-hybridoma fusions. These variants represent mouse immunoglobulin subclasses IgM, IgG1, IgG2a, and IgG2b and have growth rates equal to those of the parental hybridomas. We fused an anti-urease-secreting variant hybridoma with an anti-human choriogonadotropin (hCG)-secreting hybridoma (both of IgG1 subclass) and selected the desired product with growth media containing hypoxanthine-aminopterin-thymidine (HAT) and ouabain. Over 95% of the resulting hybrids secreted anti-urease, and 60% of these secreted anti-hCG. The bispecific nature of secreted antibodies was demonstrated in a simultaneous EIA where BiAbs, hCG, and urease (EC 3.5.1.5) were incubated together in anti-hCG-coated microwells. As little as 25 int. units of hCG per liter could be reliably detected, which is equivalent to that for antibody-enzyme conjugates in EIA.
Effect of storage temperature and shaking rate on pH and blood-gas results for two quality-control products.
Authors: Ryder K W , Jay S J , Glick M R , Woods J R 
Published: January 2020

Abstract
Directions for pre-analytical handling of ampules of two commercially available aqueous quality-control products (contrlL and G.A.S.) contain vague instructions such as "store at room temperature" and "shake vigorously" before analysis. We examined the effect of different storage temperatures (25, 31, and 38 degrees C) and shaking rate (one, two, and four shakes per second) on pH and blood-gas results. For both products, increasing the storage temperature significantly decreased pO2 results, the magnitude of the bias being greatest for those solutions with the highest O2 tensions. However, increasing the shaking rate partly offset this bias. Increasing storage temperature also decreased results for pCO2 and increased results for pH for both manufacturers' ampules with the highest CO2 tensions, and this bias was not offset by increasing the shaking rate. We conclude that both storage temperature and shaking rate must be precisely defined and carefully monitored before these products are used in a quality-control program.
Laboratory assessment of poisoning with a carbamate insecticide.
Authors: Remaley A T , Hicks D G , Kane M D , Shaw L M 
Published: January 2020

Abstract
We discuss a case of a 17-year-old white male who intentionally ingested a tick and flea insecticide and was admitted to the emergency room unconscious, with signs and symptoms of cholinergic toxicity. Capillary gas chromatography and electron-impact mass fragmentographic analysis of the patient's urine and serum demonstrated the presence of poly-ethylene glycol and propoxur (o-isopropoxyphenyl N-methyl-carbamate), a carbamate-based cholinesterase inhibitor commonly used in insecticides. The patient fully recovered, but only after a complicated hospital course. We also discuss the laboratory assessment and clinical treatment of poisoning with carbamate and organophosphate insecticides.
Hypophosphatasia: biochemical screening of a Dutch kindred and evidence that urinary excretion of inorganic pyrophosphate is a marker for the disease.
Authors: Macfarlane J D , Poorthuis B J , van de Kamp J J , Russell R G , Caswell A M 
Published: January 2020

Abstract
Hypophosphatasia is an inherited disease in which a deficiency of the bone/liver/kidney or tissue nonspecific isoenzyme of alkaline phosphatase (AP; EC 3.1.3.1) occurs. All forms of the disease are characterized clinically by defective mineralization. Several biochemical abnormalities are associated with the deficiency of AP activity, e.g., increased urinary excretion of inorganic pyrophosphate (PPi) and phosphoethanolamine (PEA). Measurement of these analytes in kindreds of patients with hypophosphatasia may be useful in identifying carriers, and in understanding the inheritance of the disease. We studied biochemically 22 members of the kindred of a 24-year-old woman with hypophosphatasia. We measured activity of AP in serum and leukocytes, and the urinary excretion of PPi and PEA. Within this kindred, urinary excretion of PPi appeared to indicate carrier status, and among the clinically normal adults, values for this analyte were inversely correlated with the activity of AP in serum. These results suggest that urinary excretion of PPi is sensitive to subtle changes in the activity of AP.
One-step protocol for assays of total and direct bilirubin with stable combined reagents.
Authors: Fossati P , Ponti M , Prencipe L , Tarenghi G 
Published: January 2020

Abstract
We describe an improved colorimetric method for assays of total and direct bilirubin in serum. Bilirubin reacts with diazotized sulfanilic acid in an acidic medium to form a blue azopigment. Total bilirubin is assayed in the presence of reaction accelerators (caffeine, urea, and citric acid), direct bilirubin in their absence. The azo compound so formed is read at the same wavelength (570 nm) in both assays. A sample blank is run in parallel. Standard curves are linear for total and direct bilirubin concentrations up to 513.0 and 256.5 mumol/L, respectively. The method is characterized by (a) use of the same protocol for both assays, i.e., a one-step procedure with short reaction time (5 min at room temperature), and (b) use of a single working solution, which, refrigerated, is stable for one month. The method is reliable, yields results that compare closely with those of the classical Jendrassik--Gróf method, is suitable for routine use, and lends itself to automation.
Effect of citrate on the urinary excretion of calcium and oxalate: relevance to calcium oxalate nephrolithiasis.
Authors: Cowley D M , McWhinney B C , Brown J M , Chalmers A H 
Published: January 2020

Abstract
Studies in 24 recurrent oxalate stone-formers have shown that values for urinary calcium excretion for this group on at-home diets vary significantly (P less than 0.001) more than values for creatinine excretions. By placing stone-formers on controlled in-hospital diets and measuring their calcium excretions, we were able to predict probable outpatient hypercalciuria (greater than 7.5 mmol/day) with a sensitivity of 95% and a specificity of 95%. In this study, the renal loss of calcium during low-calcium diets was proportional to the absorptive hypercalciuria during high-calcium diets. Calcium loading experiments in fasted stone-formers and normal subjects indicated that citrate, at citrate:calcium molar ratios ranging from 0.12 to 1, stimulated urinary calcium excretion more than did calcium carbonate loading alone. In addition, citrate also significantly (P less than 0.05) increased the excretion of urinary oxalate by two normal subjects for a given load of calcium oxalate. Malabsorption of citrate and possibly other hydroxycarboxylic acids may thus predispose to oxalate nephrolithiasis by promoting calcium and oxalate absorption.
Extraction of intracellular nucleosides and nucleotides with acetonitrile.
Authors: Au J L , Su M H , Wientjes M G 
Published: January 2020

Abstract
Extraction of intracellular nucleosides and nucleotides with acetonitrile (ACN) and water was compared with extraction with 60 g/L perchloric acid (PCA), followed by neutralization with KOH, 1 mol/L. Freshly isolated rat bone-marrow and intestinal cells were incubated with radiolabeled 5-fluorouracil (FUra) and 5-fluorodeoxyuridine. The ribose and deoxyribose nucleosides and nucleotides of FUra, and ADP and ATP in the soluble extracts were separated by HPLC and measured by scintillation counting or ultraviolet absorbance. The insoluble precipitates were digested in 1 mol/L NaOH and analyzed for the radioactive macromolecule-bound nucleotides. Both extraction methods yielded the same total (i.e., soluble and insoluble) amount of radioactivity. However, the ACN method yielded significantly more FUra nucleosides and triphosphate nucleotides and ATP in the soluble fraction, and more proteins and macromolecule-bound nucleotides in the insoluble fraction. In the PCA method, the soluble fraction contained more monophosphate nucleotides and ADP than in the ACN method. The PCA extraction procedure promoted decomposition of ATP to ADP and interfered with the ion-pairing reversed-phase HPLC assay. The ACN extraction is faster (less than 5 min) than the PCA extraction (greater than 10 min). Moreover, the ACN in the soluble extract fraction can be removed by evaporation and thus does not interfere with the HPLC analysis. Thus the ACN method evidently is suitable for extraction of nucleosides and nucleotides.
Distribution of cyclosporin A metabolites among plasma and cells in whole blood: effect of temperature, hematocrit, and metabolite concentration.
Authors: Lensmeyer G L , Wiebe D A , Carlson I H 
Published: January 2020

Abstract
Drug-free whole-blood samples supplemented with the cyclosporines and samples from 10 transplant patients receiving cyclosporin A (CsA) were equilibrated at 4, 22, and 37 degrees C for 2.5 h; the plasma and cells were separated; and the fractions were assayed by high-performance liquid chromatography (HPLC). Partitioning of CsA and metabolites among plasma and cells was diverse and not always predictable for patients' samples. Overall, although widely variable, greater than 50% of the total concentration of metabolites M1, M8, M9, M10, M16, M17, U1, U8, and U9 in whole blood was associated with the cells, whereas greater than 50% of M13, M18, M21, M25, M26, M203-218, U2, U3, U4, U5, U6, and U7 was associated with plasma. A decrease in hematocrit from 47.8% to 24%, an increase of the sample's temperature (from 4 to 37 degrees C), or an increase in analyte concentration (usually greater than 500 micrograms/L for selected metabolites) increased the relative portion associated with plasma in a nonlinear fashion. Parent CsA was most influenced by these changes; its relative concentrations in plasma varied from 18% to 50%. These data support the preferential use of whole blood for therapeutic monitoring of "cyclosporines." Through additional studies, we suggest possible mechanisms affecting the distribution phenomenon and ascribe chemical structure-distribution relationships.
Immunoradiometric assay for alpha gamma- and gamma gamma-enolase (neuron-specific enolase), with use of monoclonal antibodies and magnetizable polymer particles.
Authors: Paus E , Nustad K 
Published: January 2020

Abstract
Monoclonal antibodies were raised against neuron-specific enolase, gamma gamma-enolase, and used in an immunoradiometric assay (IRMA), with mono-disperse magnetizable particles as the solid phase. The assay's sensitivity was 0.4 microgram/L and the interassay coefficient of variation was less than 5% in the working range from 0.4 to 170 micrograms/L. Compared with our radioimmunoassay based on polyclonal antibodies, the incubation time is shorter, and precision and sensitivity are improved. The IRMA also improved detection of neuron-specific enolase in sera from patients with lung cancer without a concomitant change in measured enolase in the reference population. The better sensitivity of the IRMA results from its ability to measure alpha gamma- and gamma gamma-enolase with equal response. Ninety percent of the small-cell lung carcinoma patients (36 of 40) had increased values before treatment, compared with 7% of non-small-cell lung carcinoma patients (8 of 114).
Stratus automated creatine kinase-MB assay evaluated: identification and elimination of falsely increased results associated with a high-molecular-mass form of alkaline phosphatase.
Authors: Butch A W , Goodnow T T , Brown W S , McClellan A , Kessler G , Scott M G 
Published: January 2020

Abstract
We compared the performance of an automated assay of creatine kinase MB isoenzyme (CK-MB) mass (Stratus) with that of a CK-MB enzymatic assay routinely used at our institutions. Both of these assays use the same CK-MB-specific monoclonal antibody to immunocapture CK-MB, thus providing a direct means of comparing a mass assay with an activity assay. Routine CK-MB measurements for 206 samples within the analytical range of both assays revealed the following relationship: Stratus (micrograms/L) = 0.67 (activity U/L) + 0.18 (r = 0.95, Sx.y = 4.45). The linearity, sensitivity, and precision of the Stratus assay were acceptable for routine clinical use. Icteric, lipemic, and hemolyzed samples do not interfere with the assay. During our evaluation we identified a single, clinically significant false-positive sample. Because this patient had alkaline phosphatase values greater than 1100 U/L, we investigated additional samples with increased activities of alkaline phosphatase and found that samples from 12 of 23 patients selected for alkaline phosphatase values greater than 460 U/L produced falsely increased CK-MB values. We determined that a membrane-associated, high-molecular-mass form of alkaline phosphatase was a cause of these falsely increased values and instituted an approach to identify falsely increased Stratus CK-MB values. Samples from 23 of 1933 patients were falsely increased, the increase being clinically significant in samples from 14 of these patients. Consultation with the manufacturer resulted in the successful reformulation of the substrate/wash solution to minimize interferences from high-molecular-mass forms of alkaline phosphatase.