bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid-chromatographic assay of urinary porphobilinogen.
Authors: Jamani A , Pudek M , Schreiber W E 
Published: January 2020

Abstract
This is a rapid (10 min per sample), highly sensitive procedure for quantifying urinary porphobilinogen (PBG). Interfering substances are removed by selectively adsorbing PBG onto an ion-exchange resin. After PBG is eluted with 0.5 mol/L formic acid, Ehrlich's reagent is added to produce the chromophore, which is then injected into a liquid chromatograph equipped with a diode-array detector. PBG is separated by a linear gradient (10% to 100%) of methanol in 10 mmol/L phosphate buffer, pH 3.0. Absorbance is monitored at 555 nm. Assay response varies linearly with PBG concentration over the range 0-110 mumol/L (0-25 mg/L). As little as 1.5 mumol/L (0.3 mg/L) can be detected. In prepared urine samples with known PBG concentrations, the within-run coefficient of variation (CV) ranged from 1.7% to 3.2%, the day-to-day CV from 3.5% to 6.1%. PBG concentrations in 24-h urine collected from 25 healthy subjects were all below the detection limit of the assay (less than 1.5 mumol/L). We used the new assay to measure PBG concentrations in the urine of two patients with latent porphyria. This method is more sensitive than spectrophotometric techniques currently used for measuring urinary PBG.
Micro-quantity tissue digestion for metal measurements by use of a microwave acid-digestion bomb.
Authors: Nicholson J R , Savory M G , Savory J , Wills M R 
Published: January 2020

Abstract
We describe a simple and convenient method for processing small amounts of tissue samples for trace-metal measurements by atomic absorption spectrometry, by use of a modified Parr microwave digestion bomb. Digestion proceeds rapidly (less than or equal to 90 s) in a sealed Teflon-lined vessel that eliminates contamination or loss from volatilization. Small quantities of tissue (5-100 mg dry weight) are digested in high-purity nitric acid, yielding concentrations of analyte that can be measured directly without further sample manipulation. We analyzed National Institute of Standards and Technology bovine liver Standard Reference Material to verify the accuracy of the technique. We assessed the applicability of the technique to analysis for aluminum in bone by comparison with a dry ashing procedure.
The new International Temperature Scale of 1990 (ITS-90).
Authors: Mangum B W 
Published: January 2020

Abstract
A new international temperature scale, the ITS-90, will replace the International Practical Temperature Scale of 1968 (amended edition of 1975), IPTS-68(75), on 1 January 1990. Temperatures on the ITS-90 will agree more closely with thermodynamic temperatures; therefore, the ITS-90 represents a substantial improvement over the IPTS-68(75). Fortunately for the clinical laboratory community, the change in the scale will be at most only 0.05 degrees C or less in the range from 0 to 60 degrees C, but corrections in primary calibrations should be made so that the calibrations are based on the ITS-90.
Sensitive, direct colorimetric assay for copper in serum.
Authors: Abe A , Yamashita S , Noma A 
Published: January 2020

Abstract
We have developed a sensitive procedure for determination of serum copper by use of the color reagent 4-(3,5-dibromo-2-pyridylazo)-N-ethyl-N-sulfopropylaniline. After mixing serum sample and reagent, and incubating at 37 degrees C for 5 min, we measure the absorbance of the resulting chelate complex at 580 nm (molar absorptivity, 80,000 L.mol-1.cm-1). Results of the method varied linearly with copper concentration to at least 5 mg/L; the lower limit of detection was 0.1 mg/L. Within-run CVs were 1.6% and 3.3% for copper concentrations of 1.03 and 0.72 mg/L, respectively (n = 10 each). Between-run CV was 2.8% at 1.22 mg/L (n = 14). Results of the proposed method (y) correlated well with those determined by standard atomic absorption spectrophotometric techniques (x): y = 0.99x - 0.02 mg/L; Syx = 0.08; r = 0.977; n = 56. Iron, zinc, cadmium, cobalt, and lead do not interfere.
Quantitative analysis for organic acids in biological samples: batch isolation followed by gas chromatographic-mass spectrometric analysis.
Authors: Hoffmann G , Aramaki S , Blum-Hoffmann E , Nyhan W L , Sweetman L 
Published: January 2020

Abstract
This new method for qualitative and quantitative determination of organic acids, aldehydes, and ketones in biological samples is effective for use with urine, plasma, and amniotic fluid, and it requires no deproteinization. Isolation by batch-wise liquid partition chromatography on silicic acid follows formation of the O-(2,3,4,5,6-pentafluorobenzyl)oximes of oxoacids, aldehydes, and ketones. The total organic acid content of the sample provides a rapid screening test for metabolic abnormality. A wide-bore, bonded-phase capillary column was used for quantitative gas chromatographic-mass spectrometric analysis, followed by automated identification and quantification. Analytical recoveries were quantitative for a wide variety of metabolites. Gas-chromatographic retention indices, discriminating ions, and control ranges in amniotic fluid, plasma, and urine of adult subjects were determined for 61 biologically important compounds.
Hormonal evaluation of female infertility and reproductive disorders.
Authors: Scott M G , Ladenson J H , Green E D , Gast M J 
Published: January 2020

Abstract
Performance of the male and female reproductive systems reflects the orderly operation of the hypothalamic-pituitary-gonadal axis. Aberrant operation of this axis can result in many different reproductive disorders, including various forms of infertility. Proper evaluation of these disorders involves a multifaceted diagnostic approach, which includes a critical contribution from the clinical laboratory. This adjunctive testing, involving the measurements of peptide and sex-steroid hormone concentrations, allows the clinician to biochemically "dissect" the hypothalamic-pituitary-gonadal axis and ascertain the presence as well as location of the specific defect. In practice, the specific tests utilized during the evaluation of a patient depend upon the underlying disorder. Typically, in evaluating the reproductive disorders discussed in this review, a primary battery of tests is obtained that reflects the initial clinical presentation and physical examination. The results of these initial studies then dictate any secondary testing required to complete the evaluation. Such an approach, in use at our institution, is provided in Table 5. Although this discussion has concentrated on the laboratory assessment of the female reproductive system, it is important to remember the special case of infertility, where couples, in general, are evaluated together by the clinician. The cause of infertility can reside with the female, the male, or, in the cases of immunological "incompatibilities," a combination of the male and the female. As such, rigorous schemes for evaluating male reproductive disorders (1, 3, 89-94) and immunological incompatibilities (95-98) have been developed, and the information derived from such testing represents a critical contribution to establishing the etiology of a couple's infertility. Although the laboratory assessment of peptide and sex-steroid hormone concentrations clearly plays a pivotal role in the evaluation of reproductive disorders, these diagnostic tools probably will continue to change and improve in the years to come. Such changes will probably occur as the finer details of the operation of the hypothalamic-pituitary-gonadal axis become known. With this improved knowledge, we should have the capacity to design assays that will allow more clinically refined and biochemically precise means of diagnosing and treating specific reproductive disorders.
Significance of low serum urea nitrogen concentrations.
Authors: Lum G , Leal-Khouri S 
Published: January 2020

Abstract
The prevalence of low serum urea nitrogen concentrations (less than 50 mg/L) in our patient population was 1.2% (151 per 12,380 determinations), representing 95 individual cases. Of these, 81 of the patients' charts were located, reviewed, and classified into two groups, those with and those without hepatobiliary disease. Hepatobiliary disease was found in 36% of the 81 patients; 90% of these showed evidence of alcohol abuse, as did 19% of those without hepatobiliary disease. The remaining patients without hepatobiliary disease had various clinical conditions: psychiatric disorders (14.8%), overhydration (12.3%), endocrine disorders (7.4%), cardiovascular diseases (4.9%), prednisone administration (3.7%), and special diets (2.5%). Thus, in our patient population the most frequent cause of low serum urea nitrogen concentrations was alcohol abuse, found in about half of the cases.
Multicenter evaluation of TDx test for assessing fetal lung maturity
Authors: Russell J C , Cooper C M , Ketchum C H , Torday J S , Richardson D K , Holt J A , Kaplan L A , Swanson J R , Ivie W M 
Published: January 2020

Abstract
"TDx Fetal Lung Maturity," an automated assay that measures the relative concentrations of surfactant and albumin in amniotic fluid, was compared with the lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol determination at five clinical sites. A total of 695 amniotic fluid samples were analyzed, of which 312 were followed by delivery of the infant within three days of sample collection. Of these 312, 24 developed respiratory distress syndrome and seven developed transient tachypnea. With the cutoff for maturity set at a surfactant/albumin value of 50 mg/g, the assay showed a sensitivity of 0.96 and a specificity of 0.88 for all samples, compared with a sensitivity of 0.96 and a specificity of 0.83 for the L/S ratio. The combination of rapid assay (30 min), accurate results, and uniformity among testing centers makes the TDx assay a very promising method.
Dissociation of immunocomplexes by ionic shock for the development of immunosensors: application to measurement of alpha 1-fetoprotein.
Authors: Boitieux J L , Biron M P , Desmet G , Thomas D 
Published: January 2020

Abstract
We report here our experimental results on the reaction rate of immunological complexes and on potential repeated use of membranes as a result of dissociation of the complexes between alpha 1-fetoprotein and catalase-labeled antibodies by different buffers with various ionic strengths. The measurement consists of an immunological process and an enzymatic reaction. The protein membrane activated by glutaraldehyde for the immobilization of antibodies is fixed over an oxygen electrode. After incubation with antibody/alpha 1-fetoprotein and antibody/alpha 1-fetoprotein antibodies coupled to catalase, the reaction medium is introduced into a continuous-flow cell. Oxygen production by the catalase is measured on-line, with the electrode in contact with hydrogen peroxide. This response is correlated to the alpha 1-fetoprotein concentration of the sample. We show a typical calibration curve between 0.5 and 120 micrograms/L. Replicate (n = 20) equilibrium measurement with the same membrane gave a CV of 2.2%. The reversible immunochemical sensor has been tested for 30 measurements without significant loss of activity.
Evaluation of a kinetic method for prostatic acid phosphatase with use of self-indicating substrate, 2,6-dichloro-4-nitrophenyl phosphate.
Authors: Valcour A A , Bowers G N , McComb R B 
Published: January 2020

Abstract
The purity, spectral characteristics, and rate of nonenzymatic hydrolysis of 2,6-dichloro-4-nitrophenyl phosphate (DCNPP) were determined. Rates of DCNPP hydrolysis by prostatic acid phosphatase (PAP) and erythrocytic acid phosphatase (EAP) (both EC 3.1.3.2) were measured in the absence and in the presence of various alcohols. 1.5-Pentanediol was the most effective transphosphorylation agent for specifically enhancing the activity of PAP. 1,4-Butanediol also enhanced PAP activity but markedly inhibited EAP activity. Bovine and human serum albumin preparations also accelerated the hydrolysis of DCNPP. DCNPP can be used for the continuous or multipoint-rate assay of PAP.
Advances in cyclosporine pharmacology, measurement, and therapeutic monitoring.
Authors: Shaw L M 
Published: January 2020

Abstract
This review will focus on our current state of understanding of the cellular and molecular mechanisms by which CsA exerts immunosuppression and will present new information on: pharmacokinetic variability of CsA, selection of specimen and method for measuring CsA concentration, identity of CsA metabolites and their immunosuppressive and toxic activity, and the relationship between steady-state pre-dose concentrations of CsA in blood and response to treatment in transplant patients.
Special considerations for geriatric therapeutic drug monitoring.
Authors: Annesley T M 
Published: January 2020

Abstract
Numerous physiological changes during the normal aging process can potentially affect how drugs are handled by the body. Gastrointestinal changes include increased gastric pH, decreased intestinal motility, and decreased blood perfusion. Age-related changes in body composition and protein concentrations in plasma contribute to alterations in the distribution of drugs. Hepatic metabolism of drugs may be affected, and renal excretion via glomerular filtration or tubular secretion is diminished. The importance of each of these physiological changes in the elderly, as well as the contribution of multi-drug therapy and other external factors, is discussed.
Benzodiazepines identified by capillary gas chromatography-mass spectrometry, with specific ion screening used to detect benzophenone derivatives.
Authors: Jones C E , Wians F H , Martinez L A , Merritt G J 
Published: January 2020

Abstract
We developed algorithms for confirmation and identification of benzodiazepines and their metabolites, initially detected in urine samples by enzyme-multiplied immunoassay (EMIT). These algorithms are based on the pattern of benzophenone derivatives of benzodiazepines obtained by gas chromatography-mass spectrometry (GC-MS) with use of a modified specific ion selection mode. Benzophenone derivatives were produced by acid hydrolysis of urine samples containing benzodiazepines and (or) their metabolites. We present mass spectra of the newer benzodiazepines--alprazolam, midazolam, and triazolam--and we determined the detection limit (0.2 mg/L) for these drugs as measured with the EMIT d.a.u. benzodiazepine assay and the ETS instrument (both from Syva Co.). We conclude that these algorithms are useful mostly in forensic toxicology in which unequivocal identification of benzodiazepines is the desired goal.
Alkaline phosphatase isoenzymes in plasma in hyperthyroidism.
Authors: Tibi L , Patrick A W , Leslie P , Toft A D , Smith A F 
Published: January 2020

Abstract
Alkaline phosphatase (ALP; EC 3.1.3.1) isoenzymes were measured in the plasma of 63 untreated hyperthyroid patients (the hyperthyroid group), 58 treated hyperthyroid patients, and 100 blood donors. Total, liver, and bone ALP activities were significantly higher in the hyperthyroid group than in the treated hyperthyroid group or the blood donors. Bone ALP was more frequently and more markedly abnormal than liver ALP. Intestinal ALP did not differ significantly between the groups. The hyperthyroid patient group had significantly higher plasma calcium concentrations and lower serum parathyrin concentrations than those of the treated hyperthyroid group.
Electrothermal atomic absorption spectrometric determination of aluminum: elimination of serum matrix effects.
Authors: Gitelman H J , Alderman F R 
Published: January 2020

Abstract
An improved electrothermal atomic absorption spectrometric method for determination of aluminum in serum is described. An ammonium hydroxide/sulfuric acid diluent is used to control matrix effects from serum constituents. Because serum produces no apparent matrix effects with this diluent, one can accurately calibrate the procedure with aqueous standards.
Multipoint kinetic method for simultaneously measuring the combined concentrations of acetoacetate-beta-hydroxybutyrate and lactate-pyruvate.
Authors: Nuwayhid N F , Johnson G F , Feld R D 
Published: January 2020

Abstract
This is a multipoint kinetic method for simultaneously determining acetoacetate (AcAc) plus beta-hydroxybutyrate and lactate plus pyruvate in a single cuvette of the Multistat III centrifugal analyzer. In the first step, AcAc and pyruvate are completely reduced, using 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) and lactate dehydrogenase (EC 1.1.1.27) in the presence of excess NADH at pH 7.5, to beta-hydroxybutyrate and lactate, respectively. After dilution, the endogenous beta-hydroxybutyrate and lactate and that resulting from reduction are simultaneously oxidized by their respective dehydrogenases in the presence of excess NAD+ at pH 9.0. Adjustment of the relative enzyme concentrations allows simultaneous estimation of AcAc plus beta-hydroxybutyrate and lactate plus pyruvate by analyzing multipoint absorbance data, collected during the oxidation reaction, with use of a two-component linear-regression model. Total run-to-run CVs were 6.4% and 6.1% at 5 mmol/L beta-hydroxybutyrate and 5 mmol/L lactate, respectively. The method was designed to be useful for identifying the cause of an increased anion gap in serum.
Use of molecular probes to detect human cytomegalovirus and human immunodeficiency virus.
Authors: Spector S A , Hsia K , Denaro F , Spector D H 
Published: January 2020

Abstract
Human cytomegalovirus (HCMV) and human immunodeficiency virus (HIV) cause severe disease. The identification of these viruses in clinical specimens and understanding the progression of infection and diseases relating to HCMV and HIV are essential to develop effective means for treatment and prevention. Here we describe the application of molecular probes to the diagnosis and pathogenesis of HCMV and HIV. In situ hybridization and the amplification procedure of polymerase chain reaction are used to detect both viruses; these techniques have provided important information regarding the pathogenesis of HCMV and HIV. A new technique, target cycling, may also prove useful for the detection of viruses by enriching for target sequences. The continued application of molecular probes to pathogenetic studies of HCMV and HIV promises to further our knowledge of these viruses, and of their interaction.
Simultaneous liquid-chromatographic determination of some bronchodilators, anticonvulsants, chloramphenicol, and hypnotic agents, with Chromosorb P columns used for sample preparation.
Authors: Svinarov D A , Dotchev D C 
Published: January 2020

Abstract
We describe a simple liquid-chromatographic system for simultaneously measuring bronchodilators, anticonvulsants, hypnotics, and chloramphenicol. Use in therapeutic drug monitoring includes determination of theophylline, caffeine, chloramphenicol, ethosuximide, primidone, phenobarbital, phenacemide, phenytoin, mephenytoin, nirvanol, and carbamazepine and its bioactive metabolites within 13 min. In the "toxicology mode" theophylline, caffeine, barbital, butabarbital, pentobarbital, amobarbital, secobarbital, primidone, phenobarbital, methylprylon, glutethimide, methaqualone, phenytoin, mephenytoin, nirvanol, and carbamazepine and its bioactive metabolites are resolved within 17 min. A reversed-phase C8 column (5-microns particles) is used, with acetonitrile/water (20/80 by vol) as mobile phase. The drugs are extracted from 50 microL of serum with use of a Chromosorb P microcolumn and chloroform/isopropanol (6/1 by vol). The drugs are quantified by absorbance at 208 nm, with tolylphenobarbital as internal standard. Lower limits of detection varied from 0.05 to 0.1 mg/L, analytical recovery from 94% to 106%; CVs were less than 5.6% within run, less than 6.9% between runs.
Quantification of urinary porphyrins by liquid chromatography after oxidation of porphyrinogens.
Authors: Abe K , Konaka R 
Published: January 2020

Abstract
A quantitative "high-performance" liquid-chromatographic method is described for determining porphyrins in human urine. Porphyrinogens in urine are first converted to the corresponding porphyrins by oxidation with iodine. Uroporphyrin, hepatacarboxylic acid porphyrin, hexacarboxylic acid porphyrin, pentacarboxylic acid porphyrin, and coproporphyrin I and III isomers are then separated on a reversed-phase column and measured by fluorometry. Analysis for the six porphyrins is complete within 24 min, including reconditioning for the next sample. The detection limit (twice the signal/noise ratio) for each porphyrin was 1 nmol/L for urine (25 fmol per 50-microL injection). Mean analytical recovery of each porphyrin ranged from 85% to 91%, within-day CVs from 1.4% to 7.3%. Normal reference intervals for porphyrins were established by assaying urine samples from 75 healthy subjects. Significant sex-related differences in coproporphyrin I and III isomers were evident when the values were expressed as nanomoles per gram of creatinine. Coproporphyrin isomer ratio was estimated for utility in the diagnosis of porphyrinurias.
Practical automation and interpretation of quantitative assays of antibodies to therapeutic proteins, illustrated with human growth hormone.
Authors: Sportsman J R , Smith W C , Winely C L 
Published: January 2020

Abstract
To quantify concentrations of anti-growth hormone antibody in less than 600 serum samples by radioimmunoassay, we devised a system ("BOLAC") to process data and to execute the curve-fitting program LIGAND-PC automatically with an IBM PC-compatible computer. We fit data from each sample to four binding and one or two-antibody binding sites. Total antibody concentration is then calculated from the model that is statistically "best". This process occasionally selects a two-binding-site model that severely overestimates the antibody concentration. Errors of this kind are discarded by constraining the product of the second-site antibody's affinity and its concentration to exceed a minimum value (0.05). We evaluated the performance of the BOLAC system by assaying controls and by using computer simulations to demonstrate the high confidence levels attainable in estimation of antibody concentrations. Between-assay variability (CV) was less than 25%, and analytical recovery exceeded 90%. These figures are acceptable for an assay based on curve-fitting of competitive radioimmunoassay data, allowing clinically relevant assessments of antibody responses in patient's samples. The advantages of the BOLAC system include high throughput and the reporting of results in absolute units of affinities and concentrations.
Functional activity of protein S determined with use of protein C activated by venom activator.
Authors: Kobayashi I , Amemiya N , Endo T , Okuyama K , Tamura K , Kume S 
Published: January 2020

Abstract
A new screening procedure, an easy and specific assay for determining functional Protein S activity, has been developed, with use of Protein C activated by venom activator (Protac). Purified Protein C (100% amidolytic activity) was activated by venom activator (6 units/mL). To a mixture of 100 microL of Protein S-deficient plasma, 20 microL of sample plasma, 100 microL of cephalin (Actin), and 20 microL of activated Protein C we added 100 microL of 25 mmol/L CaCl2 solution and measured the clotting time with a KC 10 coagulometer. The functional Protein S activity correlated well with the concentrations of Protein S antigen measured by enzyme immunoassay and the Laurell rocket technique (r = 0.810 and 0.850, respectively) in normal subjects, patients with myocardial infarction undergoing warfarin therapy, and patients with liver cirrhosis.