bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amylase, lipase, pancreatic isoamylase, and phospholipase A in diagnosis of acute pancreatitis
Authors: Clavé P , Guillaumes S , Blanco I , Nabau N , Mercé J , Farré A , Marruecos L , Lluís F 
Published: January 2020

Abstract
To determine the utility of serum amylase (AMY), lipase (Lp), pancreatic isoamylase (isoA), phospholipase A (PLA), and urine AMY in the diagnosis of acute pancreatitis, samples of serum and urine were obtained on admission and every day thereafter for 5 days from 384 patients with acute abdominal pain. Diagnostic accuracy, determined as the area under the receiver operating characteristic curve, was &gt; 0.975 for serum AMY, Lp, isoA, and urine AMY. For each of these enzymes, a threshold value (twice to sixfold the upper limit of the reference values) offering diagnostic efficiency &gt; 95% could be determined. In contrast, accuracy and efficiency of serum PLA were low. The profiles of these enzymes in acute pancreatitis decreased in a parallel fashion over 5 days except for PLA. We conclude that diagnostic utilities are similar for serum AMY, Lp, isoA, and urine AMY for acute pancreatitis, provided that an appropriate threshold is established.
Sensitive method for analysis of strontium in human and animal plasma by graphite furnace atomic absorption spectrophotometry
Authors: Barto R , Sips A J , van der Vijgh W J , Netelenbos J C 
Published: January 2020

Abstract
For long-term pharmacokinetic studies in humans as well as in experimental animals, an analysis of strontium (Sr) with a low detection limit and high sensitivity is necessary. The data presented here describe the optimization of the furnace program and sample handling for measuring Sr in plasma by using graphite furnace atomic absorption spectrophotometry. The method was validated and applied to studies on the pharmacokinetics of SrCl2 in humans and rats. Calibration curves were linear up to 57.1 nmol/L. The limit of detection and lower limit of quantification were 0.21 and 0.57 nmol/L, respectively. Reciprocal sensitivity was 0.53 nmol/L Sr at A = 0.0044. The intraassay precision was 2.2%, 1.5%, and 1.1% (n = 6) at 4.57, 22.7, and 49.2 nmol/L Sr, respectively. At these concentrations, the interassay precision and recovery were 0.7%, 1.5%, and 1.8% and 100.4%, 99.1%, and 100.6% (n = 12), respectively. The endogenous Sr concentration in human plasma samples was 0.27 +/- 0.07 mumol/L (n = 18). Pharmacokinetic studies in a human volunteer and in rats demonstrated that this procedure was suited for measuring low Sr concentrations and was applicable to small sample volumes.
Spectrophotometric determination of ascorbic acid and dehydroascorbic acid
Authors: Moeslinger T , Brunner M , Volf I , Spieckermann P G 
Published: January 2020

Abstract
We present a method for measuring ascorbic acid in methanol/trichloroacetic acid extracts prepared from human plasma after enzymatic oxidation of ascorbic acid to dehydroascorbic acid by ascorbate oxidase. Samples were assayed by spectrophotometrically monitoring the kinetics of the concentration-dependent absorbance changes of dehydroascorbic acid with phosphate-citrate-methanol buffers. Ascorbic acid was determined as the difference between dehydroascorbic acid and total ascorbic acid content. The detection limit was &lt; 0.5 mumol/L. The calibration curve was linear (r &gt; 0.995) over the range 0-1000 mumol/L. Analytical recovery of ascorbic acid added to plasma was 93-105%. The between-day variance was &lt; 7%. Comparison of the spectrophotometric determination (y) with a chromatographic procedure (x) gave y = 1.02x - 0.653 (Sylx = 3.61) over the range of physiologically relevant concentrations. Total analysis time is &lt; 10 min per sample and allows the simultaneous analysis of multiple samples.
Purification and characterization of prostate-specific antigen (PSA) complexed to alpha 1-antichymotrypsin: potential reference material for international standardization of PSA immunoassays
Authors: Chen Z , Prestigiacomo A , Stamey T A 
Published: January 2020

Abstract
We describe for the first time a protocol to purify to apparent homogeneity an in vitro-prepared complex of prostate-specific antigen (PSA) and alpha 1-antichymotrypsin (ACT) by using a combination of gel filtration and ion-exchange chromatography. The purity of the PSA-ACT complex was confirmed by gel electrophoresis and Western blot. The PSA-ACT complex was stable in the pH range 6.0 to 7.8; it was also stable in various matrices, temperatures, and high concentrations of salt. Purification of the PSA-ACT complex was highly reproducible. An absorptivity of 0.99 L x g-1 x cm-1 at 280 nm was assigned to the PSA-ACT complex, based on amino acid analysis. Because PSA and ACT bind in a 1:1 molar ratio, we determined the molecular mass of the PSA-ACT complex as the mass encoded by the cDNA of ACT (plus 26% carbohydrate) plus the molecular mass of PSA (28,430 Da), which totals 89,280 Da. Using this material, we made two common calibrators, one of 100% PSA-ACT complex and one of 90% PSA-ACT complex plus 10% free PSA by volume (90:10 calibrator). Substitution of these calibrators for the manufacturers' calibrators in nine commercial immunoassays substantially reduced differences between immunoassays, especially for serum PSA values between 4 and 10 micrograms/L. The 90:10 calibrator is recommended as a universal calibrator for international standardization of PSA immunoassays.
Electrophoresis-tutor: an image-based personal computer program that teaches clinical interpretation of protein electrophoresis patterns of serum, urine, and cerebrospinal fluid
Authors: Astion M L , Rank J , Wener M H , Torvik P , Schneider J B , Killingsworth L M 
Published: January 2020

Abstract
High-resolution protein electrophoresis of serum, urine, and cerebrospinal fluid (CSF) can aid in the diagnosis of multiple myeloma, amyloidosis, macroglobulinemia, multiple sclerosis, and other diseases. Electrophoresis-Tutor is a personal computer program based on approximately 150 digital images that teaches the clinical interpretation of agarose gel electrophoretic patterns. The program is divided into the following sections: introduction, CSF, serum, urine, review of disease states, program navigator, and final exam. The CSF section describes normal and abnormal CSF findings with emphasis on oligoclonal banding, as seen in the CSF of patients with multiple sclerosis. The serum section emphasizes monoclonal gammopathy patterns but also has detailed descriptions of inflammation, liver disease, protein-losing disorders, genetic deficiencies, and other patterns. Monoclonal gammopathy is described in the context of specific associated clinical conditions (e.g., myeloma, amyloidosis). For each monoclonal gammopathy example, results of standard electrophoresis, densitometry, and immunofixation are presented. The review of disease states uses animation to illustrate the development and remission of a variety of pathological patterns. The program navigator allows the user to jump quickly to any place in the program. The optional exam contains 20 questions, and detailed feedback is given after each question. Electrophoresis-Tutor can be used as a stand-alone teaching tool, a companion to traditional instruction, or a reference source.
Novel nonseparation sandwich-type electrochemical enzyme immunoassay system for detecting marker proteins in undiluted blood
Authors: Meyerhoff M E , Duan C , Meusel M 
Published: January 2020

Abstract
A novel nonseparation electrochemical enzyme immunoassay (NEEIA) for detecting marker proteins in undiluted blood is described. The approach is based on preferential electrochemical measurement of surface-bound enzyme-labeled reporter antibody (E-Ab), relative to an excess of this reagent in the sample solution. NEEIAs are carried out on microporous membranes coated with a thin, circular area of gold. The gold serves simultaneously as a working electrode and solid phase for immobilized capture anti-protein antibodies. In the assay, analyte protein is incubated concurrently with the Ab-coated gold surface and excess E-Ab conjugate. Detection of bound E-Ab is achieved by introducing the substrate for the enzyme through the back side of the membrane. The product of bound E-Ab is detected immediately by oxidation or reduction at the gold electrode, and the resulting current is proportional to the concentration of protein in the sample. The feasibility of the NEEIA approach is demonstrated via the detection of prostate-specific antigen in undiluted plasma samples (n = 64), with alkaline phosphatase as the label. Use of multiple gold films deposited on the same porous membrane to perform simultaneous NEEIAs is also described.
Probing molecular interactions with homogeneous techniques based on rare earth cryptates and fluorescence energy transfer
Authors: Mathis G 
Published: January 2020

Abstract
A homogeneous assay method based on the long-lived fluorescence of rare earth cryptates and amplification by nonradiative energy transfer has been developed for immunoassays. The principles of the assay allow a double discrimination of the emitted signal through spectral and temporal selectivity. The cage structure of the complex, ion pairing around europium, as well as double-wavelength detection, fully shield the assay from perturbations of media. Events based on short-range interactions involving biomolecules are of tremendous importance in many domains of biology, either for analytical purposes or for molecular mechanism studies. Therefore, the principles and the reagents used to devise this homogeneous assay were adapted to various models representative of molecular and cellular processes and were chosen from the signaling pathways involved in cellular communication and expression: epidermal growth factor (EGF) receptor-ligand interaction, EGF receptor kinase activity, Jun/Fos protein-protein interaction, and DNA hybridization. Evaluation of the homogeneous assays yielded results compatible with those from comparison assays and demonstrates the versatility and wide range of applicability of this methodology.
Evaluation of thyroid status in patients with thyrotoxicosis
Authors: Braverman L E 
Published: January 2020

Abstract
The generic term thyrotoxicosis defines the clinical syndrome of hypermetabolism associated with excess amounts of circulating free thyroxine (T4) and (or) triiodothyronine (T3) concentrations, irrespective of the source of the excess hormones. The term hyperthyroidism is reserved for those patients with thyrotoxicosis caused by increased synthesis and secretion of thyroid hormones from the gland due either to thyroid stimulators in the blood or to autonomously functioning thyroid nodules and is almost always associated with an increased radioactive iodine uptake (RAIU) by the thyroid. Another major cause of thyrotoxicosis is increased release of thyroid hormone from the gland, not associated with increased synthesis, caused by inflammatory changes, and always associated with a low thyroid RAIU. The most common miscellaneous cause of thyrotoxicosis is the exogenous ingestion of excess thyroid hormone, associated with a low thyroid RAIU. The serum concentration of thyrotropin (TSH) is low in all causes of thyrotoxicosis, except for TSH-secreting pituitary tumors and selective pituitary resistance to thyroid hormones. Anti-thyroglobulin and anti-thyroid peroxidase antibodies are present in patients with autoimmune thyroid disease, and serum thyroglobulin is increased in all patients with thyrotoxicosis except those with thyrotoxicosis facticia. A decreased serum TSH and normal concentrations of serum free T4 and T3 define the syndrome of subclinical thyrotoxicosis.
Optimal laboratory testing for diagnosis and monitoring of thyroid nodules, goiter, and thyroid cancer
Authors: Ladenson P W 
Published: January 2020

Abstract
Optimal use of laboratory tests to diagnose and monitor patients with goiter, thyroid nodules, or thyroid cancer requires an appreciation of the pathophysiologic factors implicated in thyroid hyperplasia and neoplasia: growth factors (especially thyrotropin, TSH), growth-stimulating immunoglobulins, activating mutations of the TSH receptor, and other oncogenic transformations. In patients with diffuse goiter and thyroid nodules, serum TSH measurement in a highly sensitive assay excludes both primary hypothyroidism and common causes of thyrotoxicosis. In selected patients, screening for anti-thyroid peroxidase with or without anti-thyroglobulin antibodies can confirm the diagnosis of autoimmune thyroiditis. Serum calcitonin measurement is appropriate only when medullary thyroid carcinoma (MTC) is clinically suspected. Laboratory testing is essential in management of thyroid carcinoma patients after primary surgical therapy. Serum TSH measurement is vital to ensure that thyroxine replacement and TSH suppression are adequate in treatment of epithelial cancers. Serial monitoring of serum thyroglobulin (Tg) can detect tumor recurrence and quantify tumor burden. Interpretation of serum Tg results requires an appreciation of certain technical considerations (e.g., anti-Tg antibody interference) and the patient's concurrent TSH status. Periodic serum Tg measurements and 131I scans are complementary monitoring techniques. Serum calcitonin measurement and screening for ret protooncogene mutations are both valuable for identifying individuals with MTC.
Guidelines for diagnosis and monitoring of thyroid disease: nonthyroidal illness
Authors: Stockigt J R 
Published: January 2020

Abstract
On the basis of low specificity, poor positive predictive value, and cost, there is at present no basis for routine assessment of thyroid function in acutely hospitalized patients, unless clinical features suggest the possibility of thyroid dysfunction, or a patient's background increases the likelihood of thyroid dysfunction. When used in severely ill patients, estimates of both thyroxine (T4) and thyrotropin (TSH) show a high prevalence of abnormal results, but lack specificity and have poor positive predictive value for true thyroid disease. When thyroid function is tested in the critically ill, the positive predictive value for true thyroid disease of both free T4 and TSH measurements could be improved by using wider reference intervals than for unselected populations. The knowledge of nonspecific disease-related abnormalities of triiodothyronine, T4, and TSH is not currently likely to yield useful prognostic information or to alter management for individual patients. Thyroid testing should be readily available for any acutely ill patient with any clinical features that suggest thyroid dysfunction, and for groups at increased risk of thyroid dysfunction. An initial abnormal result for either TSH or free T4 estimate should be followed by combined analysis of free T4 and TSH with the best available methodology. Diagnosis of thyroid dysfunction should be based on the T4-TSH relation rather than either value alone. Persistence of an apparent diagnostic abnormality should be confirmed before therapy is commenced.
Multicenter evaluation of the Abbott IMx CA 15-3 assay
Authors: van Kamp G J , Bon G G , Verstraeten R A , Lynch D , Krikau M , Flückiger J , Ruibal A , Kenemans P 
Published: January 2020

Abstract
We describe a new fully automated procedure for the quantitative measurement of CA 15-3: the microparticle enzyme immunoassay (MEIA) technology developed by Abbott Labs. for the IMx automated immunoassay analyzer. The new IMx CA 15-3 test uses two mouse monoclonal antibodies, 115D8 and DF3. The test has a dynamic range to 250 kilounits/L and a minimal detectable dose of CA 15-3 &lt; 0.2 kilounits/L. On dilution, linearity is excellent, with recoveries ranging from 94% to 101%. Studies were conducted at four sites to evaluate the performance characteristics of this assay. The intra- and interassay CVs were &lt; 4.7% and &lt; 5.6%, respectively, and showed a between-laboratory CV &lt; 5.9%. Test results of the Abbott IMx CA 15-3 (y) were correlated with those obtained with the Centocor CA 15-3 RIA (x), a solid-phase heterologous RIA. Linear regression analysis on results for 1973 samples yielded: y = 0.97x - 2.09 (r = 0.9899, Sy/x = 22.2, range 1-4089 kilounits/L).
Evaluation of clinical assays for measuring high-dose methotrexate in plasma
Authors: Albertioni F , Rask C , Eksborg S , Poulsen J H , Pettersson B , Beck O , Schroeder H , Peterson C 
Published: January 2020

Abstract
Four routine assays commonly used for monitoring plasma methotrexate (MTX) during high-dose therapy were validated by HPLC as the comparison method. MTX and its main metabolite, 7-hydroxymethotrexate (7-OHMTX), were analyzed by HPLC with postcolumn derivatization and fluorometric detection. About 200 clinical plasma samples from 13 children with acute lymphoblastic leukemia who received 5-8 g/m2 MTX as 24-h infusions were analyzed. The fraction of measured concentrations of MTX that were within 75-125% of the values obtained by HPLC were 64.5% for enzyme inhibition assay, 56.4% for fluorescence polarization immunoassay with polyclonal antibodies (FPIA1; Abbott), 58.9% for FPIA2 (with monoclonal antibodies; Abbott), and 46.4% for enzyme-multiplied immunoassay (Emit; Syva). All nonchromatographic procedures were subject to interferences from MTX plasma metabolites or endogenous substances. The interference from 7-OHMTX was, however, somewhat less pronounced for FPIA2 (monoclonal) than for FPIA1 (polyclonal).
Evaluation of a fully automated end-tidal carbon monoxide instrument for breath analysis
Authors: Vreman H J , Baxter L M , Stone R T , Stevenson D K 
Published: January 2020

Abstract
We evaluated a novel, portable breath sampler/CO-quantifying instrument [Baby's Breath Carbon Monoxide Analyzer (BB); Natus Medical], developed for use at the bedside or with gas samples collected into bags. Bench tests demonstrated that the CO measurements were linear, accurate, and precise when compared with gas chromatography (GC) results. In vivo tests (n = 30) performed with adults showed excellent correlation between end-tidal breath CO measurements (ETCO) corrected for inhaled CO (ETCOc) as determined by BB and GC. Breath sampling efficiency was 96%. ETCOc measurements and blood carboxyhemoglobin fractions (% of total hemoglobin) corrected for inhaled CO (COHbc) correlated strongly: COHbc = 0.25 ETCOc--0.01 microL/L CO (r2 = 0.97, Sy/x = 0.47, SE slope = 0.01, n = 30). The imprecision, assessed by the mean of the population's CV for triplicate determinations, was 11%. Measurements with healthy and hemolytic term newborns showed that ETCOc values of &gt; 3 microL/L correlated with known hemolytic conditions. We conclude that this instrument is clinically reliable and can be used to noninvasively measure ETCO in neonates and adults.
Rapid and simultaneous quantification of rhamnose, mannitol, and lactulose in urine by HPLC for estimating intestinal permeability in pediatric practice
Authors: Miki K , Butler R , Moore D , Davidson G 
Published: January 2020

Abstract
Determination of intestinal permeability by measuring nonmetabolized sugars has been used to assess the integrity of intestinal mucosa. We have developed and validated a modified HPLC method for determining the concentration of L-rhamnose, mannitol, and lactulose in urine, using an amine-modified silica column and refractive index detection. Probe sugars are simultaneously resolved within 18 min. The calibration curve for each sugar is linear to 20 mmol/L. The minimum detectable concentration of lactulose is 0.05 mmol/L. Recovery of probe sugars is between 99.3% and 105.1%. Overall precision (CV) of estimation of probe sugars ranges from 4.2% to 6.5%. In 14 urine samples from healthy children who ingested the test solution containing 1 g of L-rhamnose, 1 g of mannitol, and 5 g of lactulose, the 5-h urinary excretion ratios of lactulose/rhamnose and lactulose/mannitol were 0.047 +/- 0.018 and 0.021 +/- 0.010 (mean +/- SD), respectively. This method presents a rapid, convenient, and practical technique for determining intestinal permeability in clinical pediatric practice.
Biological and clinical significance of haptoglobin polymorphism in humans
Authors: Langlois M R , Delanghe J R 
Published: January 2020

Abstract
Haptoglobin is a hemoglobin-binding protein expressed by a genetic polymorphism as three major phenotypes: 1-1, 2-1, and 2-2. Most attention has been paid to determining haptoglobin phenotype as a genetic fingerprint used in forensic medicine. More recently, several functional differences between haptoglobin phenotypes have been demonstrated that appear to have important biological and clinical consequences. Haptoglobin polymorphism is associated with the prevalence and clinical evolution of many inflammatory diseases, including infections, atherosclerosis, and autoimmune disorders. These effects are explained by a phenotype-dependent modulation of oxidative stress and prostaglandin synthesis. Recent evidence is growing that haptoglobin is involved in the immune response as well. The strong genetic pressure favoring the 2-2 phenotype suggests an important role of haptoglobin in human pathology.
Nonisotopic method for accurate detection of (CAG)n repeats causing Huntington disease
Authors: Muglia M , Leone O , Annesi G , Gabriele A L , Imbrogno E , Grandinetti C , Conforti F L , Naso F , Brancati C 
Published: January 2020

Abstract
Huntington disease (HD) is a neurodegenerative disorder caused by an expanded trinucleotide repeat (CAG)n located at the 5' end of the novel IT15 gene. Discovery of this expansion allows the molecular diagnosis of HD by measuring repeat length. We applied a simple nonisotopic method to detect (CAG)n repeats, avoiding both radioactive and Southern transfer analysis. The assay is based on direct visualization of electrophoresed PCR products, after silver nitrate gel staining. Its accurate sizing of HD alleles allows presymptomatic diagnosis of at-risk persons. By avoiding isotopic manipulations, the method is safe and accurate, with no radioactive background bands. Furthermore, because it permits direct allele visualization after gel staining, the method is simple and rapid, allowing allele sizing within hours rather than days.
Free thyroxine concentrations in serum measured by equilibrium dialysis in chronic renal failure
Authors: Okabayashi T , Takeda K , Kawada M , Kubo Y , Nakamura S , Chikamori K , Terao N , Hashimoto K 
Published: January 2020

Abstract
The serum concentration of free thyroxine (FT4) is often low in patients with chronic renal failure (CRF) with low serum concentrations of triiodothyronine (T3). We evaluated the serum FT4 concentration by using both an equilibrium dialysis RIA kit (D-FT4) and a labeled-antibody kit (M-FT4) in two different groups of CRF patients, undergoing chronic hemodialysis (HD, n = 145) or not (non-HD, n = 30), and in a group of normal healthy subjects (n = 58). Thyroid peroxidase antibodies and thyroglobulin antibodies were not detected in any patient. Serum FT4 concentrations (mean +/- SD, pmol/L) by the D- and M-FT4 assays were, respectively, 21.5 +/- 4.6 and 16.6 +/- 2.0 in the healthy subjects, 17.8 +/- 4.3 and 13.9 +/- 3.6 in the non-HD patients, and 16.9 +/- 4.9 and 10.7 +/- 1.9 in the HD patients. By the D-FT4 assay, results for both CRF groups were significantly different from those for the healthy group (P &lt;0.01), as were the results for each pair of groups by the M-FT4 assay (P &lt;0.01). FT4 values were reported as being within the healthy reference range by D-FT4 in 73 of 113 HD subjects who had low T3 and low M-FT4 values. Serum FT4 concentrations measured by both assay kits showed a significant inverse correlation with the serum concentration of creatinine (P &lt;0.01), but the serum concentrations of sex-hormone-binding globulin did not differ significantly among the three groups. Our results indicate that the low FT4 concentration measured by D-FT4 in patients with CRF, particularly those on HD, probably reflects the actual, mild nonthyroidal illness of renal failure.