bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clinical utility of liquid-chromatographic analysis of effusions for hyaluronate content
Authors: Nurminen M , Dejmek A , Mårtensson G , Thylen A , Hjerpe A 
Published: January 2020

Abstract
A previously described HPLC method for determining hyaluronate in effusions was used to analyze a consecutive series of effusions from 1039 patients with pleural fluids and from 571 patients with peritoneal fluids. A mesothelioma was verified histologically in 50 of the cases. The results were used to estimate the clinical utility of the analysis. With a cutoff of 75 mg/L for hyaluronate-derived uronic acid, assay specificity for a malignant mesothelioma was 100% and the sensitivity 56%. Only 20% of the effusions from the mesothelioma patients showed no evidence of increased production of hyaluronate. Cytological smears from the associated cell pellets were evaluated as malignant or suspicious for malignancy in only 28% or in a further 46% of the mesothelioma cases, respectively, leaving 30% of the pellets as cytologically false-negative. We also analyzed effusions from selected cases submitted from other hospitals, 154 of which had been diagnosed histologically as mesotheliomas. Concentrations of hyaluronate were increased in these cases too, but a considerable proportion of the samples showed evidence of losses of hyaluronate; consequently, the sensitivity of the assay in these samples was lower.
Enzymatic method for assaying calcium in serum and urine with porcine pancreatic alpha-amylase
Authors: Kayamori Y , Katayama Y 
Published: January 2020

Abstract
We developed a kinetic assay for calcium in serum and urine, based on the activation of porcine pancreatic alpha-amylase (EC 3.2.1.1) with 2-chloro-4-nitrophenyl-alpha-maltotrioside as substrate. The kinetic generation of 2-chloro-4-nitrophenol, monitored at 405 nm, was proportional to the concentration of calcium in serum and urine. The assay was developed and evaluated with the Cobas Bio centrifugal analyzer. The average within-run and between-day imprecision (CV) was 0.96/1.26% and 1.07/1.63%, respectively, for serum calcium and 1.50/2.54% and 1.70/2.64%, respectively, for urine calcium. Results of the proposed method (y) correlated well with those determined by atomic absorption spectrophotometry (x): y(serum) = 1.005x + 0.028 mmol/L (Sy/x = 0.058, r = 0.974, n = 50), and y(urine) = 1.017x-0.115 mmol/L Sy/x = 0.30, r = 0.981, n = 25). We also present data showing that the method is highly sensitive, rapid, relatively free of interference, and amenable to automation.
Changes in plasma amino acid concentrations in response to HIV-1 infection
Authors: Hortin G L , Landt M , Powderly W G 
Published: January 2020

Abstract
Plasma concentrations of 21 amino acids were determined for 20 control subjects and 20 subjects infected with human immunodeficiency virus type 1 (HIV). Compared with the control subjects, the HIV-infected group had lower cystine, tryptophan, and methionine (decreased 67%, 52%, and 32%, respectively, P &lt; 0.001 for each) and increased taurine (230%, P &lt; 0.001) and lysine concentrations (30%, P &lt; 0.001). Other amino acid concentrations changed modestly. Amounts of cystine, tryptophan, methionine, taurine, and lysine did not differ significantly between subgroups of HIV-infected subjects with &gt; 200 (n = 6) or &lt; 200 (n = 14) CD4+ lymphocytes per microliter, suggesting that the concentrations decrease soon after infection and change little thereafter. Activation of metabolism of cystine to taurine may explain reciprocal changes in these amino acids and known depletion of cystine and glutathione. The selective changes in amino acid profiles observed during HIV infection differ from those recognized for malnutrition or other pathological processes.
Purification of human procollagen type I carboxyl-terminal propeptide cleaved as in vivo from procollagen and used to calibrate a radioimmunoassay of the propeptide
Authors: Pedersen B J , Bonde M 
Published: January 2020

Abstract
We purified human procollagen type I carboxyl-terminal propeptide (PICP) that had been cleaved as in vivo from procollagen. PICP in serum-free medium from cultured human fetal fibroblasts was purified by thiophilic adsorption chromatography, low-pressure gel filtration, and HPLC gel filtration. The purity and homogeneity of the protein was verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Amino-terminal amino acid sequencing showed that the sequences of the alpha 1 and alpha 2 chains of this PICP were identical to those of the PICP produced in vivo. The monocomponent PICP thus purified was used as calibrator in a simple equilibrium-type RIA of PICP with polyclonal antibodies raised in rabbits. The measuring range is 0.15-3.75 nmol/L, and the assay detection limit is 0.03 nmol/L. The within-run and total CVs are 2% and 4%, respectively. The reference interval for the plasma concentration of PICP in healthy women of ages &gt; 30 years is 0.36-1.44 nmol/L (geometric mean 0.72 nmol/L, n = 154).
Carnitine determination by an enzymatic cycling method with carnitine dehydrogenase
Authors: Takahashi M , Ueda S , Misaki H , Sugiyama N , Matsumoto K , Matsuo N , Murao S 
Published: January 2020

Abstract
We describe a highly sensitive and specific method for determining L-carnitine in serum by use of carnitine dehydrogenase (EC 1.1.1.108). The method involves a new enzymatic cycling technique with NADH, thio-NAD+, and carnitine dehydrogenase, and measures the increase of absorbance at 415 nm of thio-NADH produced at 37 degrees C during the reaction: [formula: see text] The calibration curve for L-carnitine in serum was linear between 5 and 250 mumol/L. Analytical recovery was 96.5-106%, and within-run and between-run imprecisions (CV) were 0.66-4.33% and 1.02-2.56%, respectively. This method was free from interference by bilirubin, hemoglobin, various acyl-DL-carnitines, and ascorbate. The procedure is simple, rapid, accurate, and automatable. The amount of free L-carnitine in serum (53.6 +/- 11.7 mumol/L, n = 200) was greater in men than in women (45.1 +/- 14.2 mumol/L, n = 200) (mean +/- SD).
Characteristics of a two-site immunoradiometric assay for human skeletal alkaline phosphatase in serum
Authors: Panigrahi K , Delmas P D , Singer F , Ryan W , Reiss O , Fisher R , Miller P D , Mizrahi I , Darte C , Kress B C 
Published: January 2020

Abstract
This two-site IRMA includes specific monoclonal antibodies for measuring skeletal alkaline phosphatase (B-ALP) in human serum. Assay calibration is based on mass units (micrograms per liter) and was established with purified B-ALP from a human osteosarcoma cell line, SAOS-2. Precision studies demonstrated intra- and interassay CVs of 3-5% and 5-7%, respectively. Relative reactivity studies showed that the assay has a sevenfold preference for detecting B-ALP compared with the liver isoenzyme in serum. The normal reference interval for 478 healthy adults was 5-22 micrograms/L. Method comparison studies showed good correlation between this B-ALP assay (y) and commercially available electrophoretic methods (x) (y = 0.3540x + 20.5, R2 = 0.929) in a pagetic population. Temporal profiles for total ALP, this IRMA B-ALP assay, and B-ALP by electrophoresis in three pagetic patients were parallel. We conclude that this assay demonstrates good analytical performance and would be useful for the clinical assessment of metabolic bone disorders.
Changes in manganese content of mononuclear blood cells in patients receiving total parenteral nutrition
Authors: Matsuda A , Kimura M , Takeda T , Kataoka M , Sato M , Itokawa Y 
Published: January 2020

Abstract
We measured the manganese content of mononuclear blood cells and the manganese concentrations in whole blood and plasma from 31 healthy volunteers and 25 patients receiving total parenteral nutrition (TPN) (i.e., no dietary manganese). The manganese content (mean +/- 2 SD) of mononuclear blood cells and the manganese concentration in whole blood and plasma in the healthy volunteers were 8.84 +/- 4.18 ng/10(8) cells, 11.21 +/- 4.68 micrograms/L, and 1.21 +/- 0.72 micrograms/L, respectively. The manganese content of mononuclear blood cells from patients receiving TPN gradually decreased, falling below the lowest limit of the normal range by 21 weeks (95% confidence limits, 13-30 weeks) after starting TPN. Manganese concentrations in whole blood and plasma were within normal limits during our study period. These results suggest that the manganese content of mononuclear blood cells may better indicate manganese nutritional status than whole-blood or plasma concentrations.
Age-related reference values for urinary organic acids in a healthy Turkish pediatric population
Authors: Guneral F , Bachmann C 
Published: January 2020

Abstract
Organic acid concentrations were quantified by gas chromatography and the individual acids identified by mass spectrometry in urine specimens from a healthy Turkish pediatric population of ages 2 days to 16 years, subdivided into five age groups. We quantified 69 organic acids (32 major and 37 minor components) and report here the median values and percentiles for each compound, adjusted for creatinine content, for the five groups. Concentrations of most of the organic acids tend to decrease with age but display substantial differences between age groups. This emphasizes the importance of comparing patients' data with age-matched reference data. Correlations between the excretion of organic acids and protein or caloric intake were significant for several compounds.
Rapid HPLC determination of total homocysteine and other thiols in serum and plasma: sex differences and correlation with cobalamin and folate concentrations in healthy subjects
Authors: Jacobsen D W , Gatautis V J , Green R , Robinson K , Savon S R , Secic M , Ji J , Otto J M , Taylor L M 
Published: January 2020

Abstract
High-performance liquid chromatography with fluorescence detection has been utilized for the rapid determination of total homocysteine, cysteine, and cysteinylglycine in human serum and plasma. Our earlier procedure (Anal Biochem 1989;178:208), which used monobromobimane to specifically derivatize thiols, has been extensively modified to allow for rapid processing of samples. As a result, &gt; 80 samples a day can be assayed for total homocysteine, cysteine, and cysteinylglycine. The method is sensitive (lower limit of detection &lt; or = 4 pmol in the assay) and precise (intra- and interassay CV for homocysteine, 3.31% and 4.85%, respectively). Mean total homocysteine concentrations in plasma and serum were significantly different, both from healthy male donors (9.26 and 12.30 mumol/L, respectively; P &lt; 0.001) and healthy female donors (7.85 and 10.34 mumol/L, respectively; P &lt; 0.001). The differences in total homocysteine between sexes were also significant (P = 0.002 for both plasma and serum). Similar differences were found for cysteine and cysteinylglycine. We found a significant inverse correlation between serum cobalamin and total homocysteine in men (P = 0.0102) and women (P = 0.0174). Serum folate also inversely correlated with total homocysteine in both sexes.
Limit of detection (LQD)/limit of quantitation (LOQ): comparison of the empirical and the statistical methods exemplified with GC-MS assays of abused drugs
Authors: Armbruster D A , Tillman M D , Hubbs L M 
Published: January 2020

Abstract
The limit of detection (LOD) for any analytical procedure, the point at which analysis is just feasible, may be determined by a statistical approach based on measuring replicate blank (negative) samples or by an empirical approach, consisting of measuring progressively more dilute concentrations of analyte. The limit of quantitation (LOQ), or concentration at which quantitative results can be reported with a high degree of confidence, may likewise be determined by either approach. We used both methods to determine LOD and LOQ for forensic gas chromatographic-mass spectrometric (GC-MS) analyses of abused drugs. The statistically determined LOD and LOQ values for these assays underestimated the LOD because of the large imprecision associated with blank measurements and the inability of blank samples to meet typical GC-MS acceptance criteria. The empirical method provided much more realistic LOD values, supported by reasonable experimental data, and are 0.5-0.03 the magnitude of the corresponding statistical LODs. The empirical LODs and LOQs are identical for these GC-MS assays. The observations made here about the LOD/LOQ for specific forensic GC-MS procedures are generally applicable to any type of analysis.
Simultaneous separation and quantification of free and metal-chelated protoporphyrins in blood by three-dimensional HPLC
Authors: Sato H , Ido K , Kimura K 
Published: January 2020

Abstract
In this new method for simultaneous separation and quantification of free and metal-chelated porphyrins in blood, the porphyrins are extracted from blood samples with a mixture of diisopropylamine:water:methanol (25:100:900, by vol) and separated by HPLC elution. The data are collected in three-dimensional form with a microcomputer. This method permits a high recovery of protoporphyrin (PP) and Zn-chelated PP as well as heme from blood. By this method, the amounts of these analytes in erythrocytes from normal or abnormal subjects can be determined more accurately than by conventional methods.
Enzymatic quantification of 1,5-anhydro-D-glucitol: evaluation and clinical application
Authors: Phillipou G , James S K , Frith R G , Farrant R K , Phillips P J 
Published: January 2020

Abstract
We investigated an enzymatic colorimetric procedure for quantification of plasma 1,5-anhydro-D-glucitol (AG) with respect to its reproducibility and application for evaluation of diabetes mellitus. Assay specificity is critically dependent on the two-layer ion-exchange column chromatography procedure to remove glucose from the sample. For female nondiabetic subjects (n = 110, ages 22-36 years) the median plasma AG concentration was 143 mumol/L (range 70-209 mumol/L); there was no relation to body mass index (BMI), fasting plasma glucose, or insulin, but an inverse association was noted for age. For a group of older subjects (n = 69, 70-85 years), no association between AG concentrations and sex, age, BMI, or various medical conditions was found. In diabetic subjects (n = 170) a significant inverse nonlinear relation existed between plasma AG and glycohemoglobin (GHb) such that at GHb &gt; 8.5%, AG concentrations were typically &lt; 50 mumol/L. The findings confirm that plasma AG, in the presence of normal renal function, is a reliable marker for hyperglycemia.
Role of biomarkers in identifying and understanding environmentally induced disease
Authors: Silbergeld E K , Davis D L 
Published: January 2020

Abstract
Establishing associations between environmental agents and disease presents challenges to both epidemiologists and toxicologists, particularly in cases of complex gene-environment interactions and when there is a long latency between exposure and disease. Biologic markers, physiological signals that reflect exposure, early cellular response, or inherent or acquired susceptibilities, provide a new strategy for resolving some of these problems. Biomarker research assumes that toxicant-induced diseases are progressive and that injury proceeds from entry of the toxicant into target cells, which induces subcellular biochemical events, to cell- and organ-level events that eventually induce irreversible or persistent organism dysfunction. The epidemiologic value of a biomarker lies in its ability to predict backward toward exposure and forward toward risk of clinical outcome, which is largely unknown. Research in mechanistic toxicology will advance the range of useful biomarkers in epidemiology and clinical medicine.
Reference limits in occupational toxicology
Authors: Aitio A 
Published: January 2020

Abstract
Two categories of reference limits can be discerned in biological monitoring: The first category identifies individuals who have been exposed to a toxic agent at work, and is based on the distribution of the concentration of the agent or its metabolite in the population that has not been exposed to the agent at work. The second category, for which the term biological action level (BAL) is proposed, provides a guideline on the level of exposure that is acceptable. These levels may be either directly health-based or derived from good working practices. Thus BAL is a biological equivalent for the generic term occupational exposure limit. BAL should be independent of legal overtones, and implies that workers' exposure should be reduced.
Cadmium: exposure markers as predictors of nephrotoxic effects
Authors: Lauwerys R R , Bernard A M , Roels H A , Buchet J P 
Published: January 2020

Abstract
Cadmium (Cd) is a cumulative element with a biological half-life of &gt; 10 years in humans. The total amount of Cd accumulated in the liver and in the kidney can be measured in vivo by neutron activation (or x-ray fluorescence), but this technique does not necessarily measure the fraction that is biologically active. At low exposure (i.e., general environmental exposure or moderate occupational exposure), blood Cd is mainly influenced by the last 2 to 3 months of exposure. Under such conditions, the Cd concentration in urine mainly reflects the amount of Cd stored in the body, particularly in the kidney. In Europe and the US, the Cd reference values are usually &lt; 2 nmol/mmol creatinine. Because most of the Cd in urine is probably bound to metallothionein, the changes in the urinary metallothionein concentration parallel those of Cd. The determination of Cd concentration in hair is of limited value because in humans it is difficult to distinguish between externally deposited and endogenous Cd. Fecal Cd is a good indicator of the oral daily intake. The results of several cross-sectional epidemiologic studies of the relation between the prevalence of renal dysfunction and Cd concentration in urine led us to propose a biological limit value for Cd of 5 and 2 nmol/mmol creatine for adult male workers and the general population, respectively.
Methylmercury: significance of intrauterine and postnatal exposures
Authors: Grandjean P , Weihe P , Nielsen J B 
Published: January 2020

Abstract
Outbreaks of methylmercury poisoning in Japan and Iraq have demonstrated the sensitivity of the fetus to neurotoxic effects. Based on toxicokinetics and considerations of practicability, the optimal biomarker of methylmercury exposure is the hair concentration, but whole-blood measurements of mercury are also useful. Dose-response relations are still incompletely known, especially concentrating developmental neurotoxicity under conditions of chronic exposure. Available evidence indicates that neurobehavioral dysfunction in children may occur if the maternal mercury concentration in hair is &gt; 6 micrograms/g (30 nmol/g). This value corresponds to a blood mercury concentration of approximately 24 micrograms/L (120 nmol/L). The period of maximum sensitivity of the nervous system to methylmercury toxicity is unknown, but the transfer of mercury to the newborn through human milk may represent an additional risk. In view of the wide occurrence of mercury contamination in developing countries, increased use of the exposure biomarkers is encouraged.
Chlorinated dibenzo-p-dioxins and -furans: problems in analysis of biomarkers
Authors: Schlatter C 
Published: January 2020

Abstract
Although dioxin concentrations in adipose tissue or blood lipids can suitably be used for toxicological evaluation, such data usually are not yet asked for in the risk assessment process, which is still based mainly on theoretical calculations of possible environmental exposure instead of measured concentrations in humans. The latter is necessary because the substantial kinetic differences between experimental animals and humans observed for dioxins lead to different organ concentrations and distribution patterns. Hence the classical extrapolation method for assessing toxicity on the basis of the administered oral dose is inappropriate. Also, the applied models and theoretical assumptions that often predicted a considerable human exposure by the oral, dermal, or inhalatory route in the case of contaminated soil and dust have not proved to be pertinent, since the actual burdens determined by biomonitoring in people living at heavily contaminated sites did not show markedly increased concentrations.
Exposure to mixtures and congeners of polychlorinated biphenyls
Authors: Skerfving S , Svensson B G , Asplund L , Hagmar L 
Published: January 2020

Abstract
There are 209 congeners of polychlorinated biphenyls (PCBs), the metabolism and toxicity of which vary by congeners. Use of PCBs is now restricted, but environmental contamination and human exposure persist. Analysis for "total PCBs" in biological samples gives limited information; congener-specific analysis is far more informative, but more complicated. Concentrations of congeners in serum/plasma, adipose tissue, or milk are useful biomarkers of exposure. Lipids may contain similar concentrations and congener patterns, but these vary between exposures and are different from those of the corresponding exposure mixtures; hence, analysis of lipids cannot be used to identify the original exposure. Some non- and mono-ortho congeners may attain a coplanar conformation, which renders them capable of a dioxin-like action. Toxic equivalency factors (TEFs) have been used to sum that risk as toxic equivalents (TEQs), which are considerably different from congener concentrations. No reliable data have been developed on the relationship between concentrations of "total PCBs" or congeners in biological samples and effects of PCBs on human health, mainly because of the various analytical procedures involved and confounding exposures.
Quality assurance, accreditation, and certification: needs and possibilities
Authors: Dybkaer R 
Published: January 2020

Abstract
Demonstrable quality of laboratory services entails two parts. First, one needs a quality policy statement, identification of user needs, choice of measurement procedures, reference measurement system to provide traceability, control materials, and proficiency testing with materials having reference-measurement-assigned values. Second, it may be useful to obtain recognition of competence in addition to the director's certificate, such as Good Laboratory Practice (when studying toxicity of chemicals), ISO 9000 certification of a self-defined quality system, nongovernmental professional accreditation, or, most demanding, governmental accreditation according to European Standard EN 45,001 with some modifications. These require external quality audit; ISO and EN also require a quality manual, which is valuable documentation in any case.
Monitoring the worker and the community for chemical exposure and disease: legal and ethical considerations in the US
Authors: Ashford N A 
Published: January 2020

Abstract
Biomonitoring of workers and communities raises important legal and ethical concerns, but the two contexts are different. Monitoring workers is usually done by, or at the instigation of, the employer who, in law, is responsible for their health and safety. Whenever worker monitoring leads to the removal of workers, difficult issues emerge affecting labor-management relations, labor law, and discrimination law. Resulting legal and ethical questions are usually framed with the context of the employment contract or labor relationship. In contrast, public health or environmental officials may be the driving force behind biomonitoring of the community. No employer-employee relationship exists, and the doctor-patient relationship may be tenuous. The community may often request biomonitoring, but the situation is no less contentious. On the basis of an historical view of monitoring events within the US, mechanisms are suggested to promote positive interactions between employers and workers and among agencies, individuals, and groups in the monitoring of chemically contaminated communities.