bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of cholesterol oxidase in a patient with Cushing's syndrome.
Authors: Davey D D , Alber D B , Ryder K W , Jones J M , Hostetler M L , Moorehead W R , Oei T O 
Published: January 2020

Abstract
Serum from a patient with Cushing's syndrome who was being treated with mitotane contained components that interfered with determination of cholesterol in the Du Pont aca. A measured concentration of cholesterol of 4.19 g/L in the undiluted serum increased to a calculated concentration of 9.50 g/L in diluted serum. Adding additional cholesterol oxidase (EC 1.1.3.6) overcame the reaction inhibition in the undiluted sample; adding additional cholesterol esterase (EC 3.1.1.13) had no effect. There is the potential for clinically significant underestimation of cholesterol with the aca in such patients, because the interference may remain undetected. On the other hand, the aca accurately quantified undiluted specimens containing as much as 10 g of cholesterol per liter when mitotane was not present.
Direct spectrophotometry of serum hemoglobin: an Allen correction compared with a three-wavelength polychromatic analysis.
Authors: Noe D A , Weedn V , Bell W R 
Published: January 2020

Abstract
An Allen correction and a polychromatic analysis are about equally effective in minimizing effects of interference by bilirubin and triglyceride turbidity in the direct spectrophotometry of serum hemoglobin: interference from bilirubin is nearly eliminated, that from turbidity substantially decreased. The limit of detectability of hemoglobin is 8 mg/L in the presence of a moderate concentration of bilirubin. A change in hemoglobin concentration as small as 16 mg/L can be detected in serum having a concentration near the upper limit of the reference interval, i.e., at the medical decision level. The polychromatic formula gives concentration estimates approximately 5% greater than those of the Allen correction. The formula for the Allen correction is hemoglobin (mg/L) = 1.68 mA415 - 0.84 mA380 - 0.84 mA450 . That for the polychromatic analysis is hemoglobin (mg/L) = 1.65 mA415 - 0.93 mA380 - 0.73 mA470 .
Apolipoprotein E polymorphism and hyperlipidemia.
Authors: Assmann G , Schmitz G , Menzel H J , Schulte H 
Published: January 2020

Abstract
We tested apolipoprotein E phenotypes in 1557 normolipidemic factory workers and 822 hyperlipidemic hospital patients. We distinguished six different apolipoprotein E phenotypes and determined their frequencies in normolipidemia (factory workers), hypertriglyceridemia, hypercholesterolemia, and mixed hyperlipidemia. For the three homozygous phenotypes E3/3, E4/4, and E2/2, the percentage distribution in the normolipidemic group was 62.2%, 2.2%, and 0.9%, respectively; for the three heterozygous phenotypes E4/3, E3/2, and E4/2, we determined frequencies of 19.9%, 11.7%, and 2.9%, respectively. A higher prevalence of E2/2 homozygosity was observed in hypertriglyceridemic persons (2.5%) and persons affected by mixed hyperlipidemia (5.0%). E4/4 homozygosity occurred more often among hypercholesterolemic patients (5.0%) than normolipidemic persons (2.2%). These data suggest that E2/2 homozygosity and E4/4 homozygosity both predispose to hyperlipidemia. Patients affected by mixed hyperlipidemia should be investigated for their apolipoprotein E polymorphism because of the possible linkage of apolipoprotein E2/2 homozygosity, hyperlipidemia, and atherosclerosis.
Trace elements in serum from Pakistani patients with acute and chronic ischemic heart disease and hypertension.
Authors: Khan S N , Rahman M A , Samad A 
Published: January 2020

Abstract
We examined sera from 159 patients with ischemic heart disease and hypertension and from 50 apparently healthy control subjects for content of trace elements, cholesterol, triglyceride, and enzymes. Concentrations of copper, cobalt, cholesterol, and triglyceride were increased in all patients, but calcium was decreased in patients with hypertension, acute myocardial ischemia, and acute myocardial infarction. Also accompanying acute myocardial infarction were decreased concentrations of zinc and iron but increases in nickel, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. Magnesium concentration was lower in patients with acute myocardial ischemia. In acute myocardial infarction, the concentrations of copper, zinc, and iron were higher after 21-30 h (as compared with the values at 0-10 h), by which time concentrations of calcium, magnesium, cobalt, and alanine aminotransferase had decreased. The variation in concentration of trace elements in serum from cases of ischemic heart disease and hypertension corresponds to the severity of the disorder.
Carboxypeptidase-catalyzed hydrolysis of C-terminal lysine: mechanism for in vivo production of multiple forms of creatine kinase in plasma.
Authors: Perryman M B , Knell J D , Roberts R 
Published: January 2020

Abstract
Human myocardial creatine kinase isoenzyme MM is present as a single form in tissue, but upon its release into plasma two additional forms, with faster anodal migration, are apparent on polyacrylamide electrophoresis. We designate the three forms as MM3, MM2, and MM1 in increasing order of anodal mobility. When tissue creatine kinase isoenzyme MM (MM3) is incubated with either carboxypeptidase N or carboxypeptidase B it is converted into the two additional forms, MM2 and MM1. The carboxy terminal amino acid of human, canine, and rabbit tissue MM3 was determined to be lysine, a specific substrate for carboxypeptidases N and B. Evidently the mechanism for the production of multiple forms of creatine MM in human plasma is the hydrolysis of a positively charged C-terminal lysine residue from one M subunit (MM2), followed by hydrolysis of the C-terminal lysine from the other subunit (MM1).
Quantification of pepsin A activity in canine and rat gastric juice with the chromogenic substrate azocoll.
Authors: Will P C , Allbee W E , Witt C G , Bertko R J , Gaginella T S 
Published: January 2020

Abstract
The activity concentration of pepsin may be quantified by using azocoll as a chromogenic substrate. The measured enzyme activity is constant between pH 1.2 and 3.4 and is proportional (r = 0.61) to the activity measured with hemoglobin as substrate. The activity of purified porcine pepsin is inhibited by pepstatin A with an apparent Ki of 115 nmol/L. The azocoll method is useful for measuring changes in pepsin secretion in response to pharmacological agents. For example, pepsin activity of canine gastric juice is decreased by 80% after in vivo administration of 0.5 mg of the synthetic trimethyl prostanoid Ro 22-6923 per kilogram of body weight. The method is sufficiently sensitive to measure the pepsin activity in 0.2 microL of canine gastric juice with a CV of approximately 10%, is simpler than the hemoglobin-substrate methods, and the substrate is commercially available.
Sensitive non-radioisotopic method for measuring lipoprotein lipase and hepatic triglyceride lipase in post-heparin plasma.
Authors: Nozaki S , Kubo M , Matsuzawa Y , Tarui S 
Published: January 2020

Abstract
In this method for measuring lipoprotein lipase (LPL) and hepatic triglyceride lipase (H-TGL) in post-heparin plasma, we determine the released free fatty acids enzymically. After release, they are extracted by Dole 's method (J. Biol. Chem. 235: 2595-2599, 1960), solubilized with Triton X-100, then measured with an enzymic kit (NEFA Kit-K; Nippon Shoji Kaisha Ltd.) after residual turbidity is removed by centrifugation with chloroform. A 5-microL sample of post-heparin plasma suffices to measure the activity of LPL and H-TGL; thus the method is as sensitive as the radioisotopic method. Selective assay of LPL and H-TGL, by adding sodium dodecyl sulfate to inactivate H-TGL or NaCl to inactivate LPL, is also feasible. The mean activities +/- SD of LPL and H-TGL in plasma of normal healthy men were respectively 9.4 +/- 2.3 mumol/h per milliliter (157 +/- 38 U/L) and 20.1 +/- 10.4 (335 +/- 173 U) mumol/h per milliliter (U/L).
A direct comparison of two slope-estimation techniques used in method-comparison studies.
Authors: Parvin C A 
Published: January 2020

Abstract
Least-squares regression estimation of the slope and intercept in method-comparison studies is the most common method of data evaluation despite well known theoretical difficulties with this approach. An alternative estimation technique has been suggested, which avoids some of these theoretical difficulties. I developed an exact mathematical relationship between these two slope estimates in order to directly compare their characteristics. A simple approximate formula for the relative difference between the two slope estimates is also derived. Using these mathematical relationships, I compare the two estimation techniques, using data from published method-comparison studies. In most of the published method comparisons the differences between slope estimates were trivial, but in some the differences were large enough to have warranted use of the alternative slope estimate.
Optimized liquid-chromatographic determination of metronidazole and its metabolites in plasma.
Authors: Gibson R A , Lattanzio L , McGee H 
Published: January 2020

Abstract
Metronidazole and its known metabolites in plasma can be rapidly separated by a "high-pressure" liquid-chromatographic method that can also be adapted for rapid determination of tinidazole. Samples deproteinized with trichloroacetic acid (50 g/L final concentration) undergo isocratic separation on a reversed-phase C18 column eluted with an 8/92 (by vol) mixture of acetonitrile/KH2PO4 (5 mmol/L, pH 3.0). The method is sensitive, reliably detecting as little as 25 micrograms of metronidazole and (or) its metabolites per milliliter of plasma. The detector response varied linearly with concentration for all compounds tested over a wide range (25-500 micrograms/L). Within-day and between-day variation was generally less than 2.5% for all concentrations of all compounds tested. Various other antibiotics tested did not interfere.
Self testing, an emerging component of clinical chemistry.
Authors: Free A H , Free H M 
Published: January 2020

Abstract
Self testing as a phase of health delivery has been utilized for approximately 70 years, but within the last two decades there has been an increasing interest in and use of self testing. The practice of self testing has a sound basis, which involves medical relevancy, cost containment, and convenience. It is reasonable to anticipate that self testing will increase in the future as medical needs and available procedures are established. The clinical chemist, the physician, and the industrial producer of test systems all have important roles in self testing. The clinical chemist, whether in a hospital laboratory or in an industrial setting, has the responsibility to create new self-testing procedures that represent expansion and improvement over those currently available. The clinical chemist also has a critical role in the evaluation of new self-testing procedures and in validating their capability of providing high-quality information. The provision of quality-assurance programs and proficiency programs for the user can most effectively be carried out by clinical chemists. The clinical chemist can also play an important role as a consultant, teacher/educator, and trouble shooter in recognizing and helping solve problems that may appear in various areas of self testing. The classic role of the physician has been to diagnose disorders of the patients and provide therapy for effective care. The role of the physician in self testing is quite comparable to his usual role, since the ultimate diagnosis of disease will be carried out by the physician and he will continue to be the source for definition of therapy. A major portion of self testing will be carried out with the recommendation of a physician, and he will maintain a role in the interpretation of results. The physician needs to be familiar with self-testing practices and procedures and be prepared to provide interpretation of self-testing results. Industry supplies an increasing proportion of reagent systems and instruments for the clinical laboratory. The supplying of reagent systems and small instruments for self testing is almost completely a role of industry. The creation and funding of new products for self testing will be provided by industry to a large extent. A critical function of industry is to provide high-quality products and efficient customer service to the self-testing component of health delivery. We have each played a role in self testing over a period of approximately 40 years. During this period self testing has become an important phase of clinical laboratory practice.(ABSTRACT TRUNCATED AT 400 WORDS)
A specific kinetic assay for tripeptide aminopeptidase in serum.
Authors: Kanda S , Sudo K , Kanno T 
Published: January 2020

Abstract
This is a method for measuring tripeptide aminopeptidase (EC 3.4.11.4) activity in serum. L- Leucylglycylglycine is used as substrate, and the reaction is followed by monitoring the absorbance increase at 340 nm when NAD+ is reduced to NADH in the presence of an excess of leucine dehydrogenase. This principle allows kinetic determination of the enzyme without interference by carboxypeptidases. Amastatin is added to the reaction mixture to prevent nonspecific hydrolysis of the substrate catalyzed by other aminopeptidases. As final reaction concentrations we recommend (per liter): 100 mmol of Tris buffer (pH 8.2), 4.0 mmol of L- leucylglycylglycine , 10 kU of leucine dehydrogenase, 3.8 mmol of NAD+, and 85 mumol of amastatin . The assay is suited to modern enzyme analyzers and has high precision.
Automated kinetic determination of angiotensin-converting enzyme in serum.
Authors: Harjanne A 
Published: January 2020

Abstract
In this automated kinetic modification of a previous method (Anal Biochem 95: 540-548, 1979) for determining angiotensin-converting enzyme (EC 3.4.15.1), 3-(2- furylacryloyl )-L- phenylalanylglycylglycine is used as the substrate. The change in absorbance at 340 nm is used to monitor hydrolysis of the substrate. The rate of hydrolysis is roughly threefold greater than with previously reported substrates, so assay time and sensitivity are improved.
Differential immunoadsorption coupled with rate nephelometry for estimation of DNA-binding immunoglobulins.
Authors: DeBari V A , Nicotra J , Blaney J F , Schultz E F , Needle M A 
Published: January 2020

Abstract
We describe a technique for estimating the mass of anti-DNA antibodies by immunonephelometry of serum immunoglobulins (IgG, IgA, IgM) before and after adsorption onto DNA bound to agarose-polylysine columns. Sixteen patients with systemic lupus erythematosus and 16 age- and sex-matched controls were studied. Precision was determined for high-value (in 10 patients) and low-value (in nine controls) ranges for each of the immunoglobulins. Within-run CVs ranged from 3.0% (IgG, controls) to 11.8% (IgA, patients); between-run CVs ranged from 15.5% (IgG, patients) to 25.2% (IgM, patients). We found anti-DNA antibody concentrations (mean +/- SD) in systemic lupus erythematosus of 1.981 +/- 1.015 g/L for IgG (controls: 0.243 +/- 0.231, p less than 0.001), 0.257 +/- 0.215 g/L for IgA (controls: 0.038 +/- 0.035, p less than 0.001), and 0.282 +/- 0.234 g/L for IgM (controls: 0.191 +/- 0.165, p greater than 0.05). Sensitivity and linearity are such that fivefold dilutions of patients' serum with either a buffered albumin solution or control serum yielded values close to the expected values for IgG. Similarly diluted sera gave inordinately high values in the radiometric binding assay. Neither parametric (linear regression) nor nonparametric correlation methods (Spearman's rank and Kendall's tau) show a significant correlation between patients' data obtained by the present technique and that by a radiometric binding assay (p greater than 0.05), although combined data from patients and controls demonstrate a significant nonparametric correlation (p less than 0.005 for Spearman's and p less than 0.02 for Kendall's).
Discordant inter-kit results in the radioimmunoassay for choriogonadotropin in serum.
Authors: Rzasa P J , Caride V J , Prokop E K 
Published: January 2020

Abstract
Discordant results for concentrations of choriogonadotropin (HCG) in sera from five of 162 women are reported, as determined with four commercial radioassay kits: Becton-Dickinson, Clinetics, Corning, and Hybritech. Results ranged from 11.2 to 36.7 int. units/L, when assayed with the Becton-Dickinson kit, but HCG was not detectable when assayed with the other kits. None of the patients was pregnant, and none had evidence of persistent trophoblastic or nontrophoblastic disease. Concentrations of lutropin, follitropin, thyrotropin, triglycerides, cholesterol, protein, and albumin were normal. Assay of diluted sera did not parallel the standard curve, and nonspecific binding in the patients' samples was negligible. Some kits for HCG may be influenced by inherent methodological factors or interfering serum constituents, which can lead to spurious results.
Multivariate examination of response surfaces around the reaction conditions for the Scandinavian Society's recommended method for creatine kinase determinations.
Authors: Sampson E J , Whitner V S , Ali M , Fast D M 
Published: January 2020

Abstract
We examined the reaction surfaces around five variables (imidazole, ADP, creatine phosphate, magnesium, and pH) in the Scandinavian method for determining creatine kinase, using factorial experimentation (five level, five factor) at reaction temperatures of 30 and 37 degrees C. Theoretical response surfaces were computed by fitting a quadratic polynomial equation to the experimental data by least-squares regression. Essentially no differences were apparent in the theoretical curves among the five specimens we analyzed, or between reaction temperatures. Our response-surface data showed the following: for pH and imidazole, activity optima in the region of the Scandinavian conditions; for creatine phosphate, a broad plateau over the concentration range investigated (10 to 50 mmol/L); and for magnesium and ADP, gently increasing contours with maximal creatine kinase activity at concentrations greater than those investigated in our study (magnesium 15 mmol/L, ADP 3.5 mmol/L).
Purification of lactate dehydrogenase isoenzymes one, two, and three from human erythrocytes.
Authors: Pridgar E M , Moses G C , Henderson A R 
Published: January 2020

Abstract
Lactate dehydrogenase (LD) isoenzymes 1, 2, and 3 were prepared from human erythrocytes by sequential ion-exchange chromatography followed by general-ligand (AMP analog) affinity chromatography. Respective yields, purification factors, and specific activities (kU per gram of protein) were 25%, 4394-fold, and 209.7; 40% 4385-fold, and 199.1; and 18%, 7565-fold, and 192.9. The respective preparations contained less than 0.5% of contaminating LD isoenzyme activity as judged from electrophoresis on thin-layer agarose, were homogeneous as judged by electrophoresis on polyacrylamide gel (both in the presence and absence of sodium lauryl sulfate), and showed minor contamination by other LD isoenzymes as judged by analytical isoelectric focusing. We think that these preparations would be useful as human-based calibrating or reference materials. Their purity is such that these preparations could also be used as antigens for the development of suitable antisera.
Simple screening test for qualitative detection of increased delta-aminolevulinic acid in urine.
Authors: Tishler P V , Winston S H 
Published: January 2020

Abstract
A simple qualitative procedure for demonstrating increased delta-aminolevulinic acid (ALA) in urine is needed to identify individuals with an inherited deficiency of the enzyme ALA dehydratase, a newly described porphyria-like syndrome. The present procedure includes two steps, the last of which is carried out only on samples that are positive in the first step. Urine is tested for pyrroles, preformed or formed by heating with acetylacetone, by looking for a pink color after p-dimethylaminobenzaldehyde is added. Samples showing the color are next tested for ALA by adsorbing natural pyrroles onto Dowex-1 in sodium acetate, heating the supernate with acetylacetone, adsorbing the resulting aminoketone pyrroles onto Dowex-1 in water, separating the ALA from other aminoketones by differential extraction, and again looking for a pink color with p-dimethylaminobenzaldehyde. Positive urines, those with concentrations of ALA greater than or equal to 10-15 mg/L, yield a pink color in each step. Samples with greater than 30 mg/L ALA show a magenta color. Aminoacetone in excess of 3 mg/L ALA also yields a pink color, but such a concentration in urine is unlikely. Many samples can easily be tested concurrently.
Application of enzyme immunoassays to coagulation testing.
Authors: Amiral J , Adalbert B , Adam M 
Published: January 2020

Abstract
Enzyme immunoassays are very useful for the detection of low concentrations of coagulation proteins and pathological markers in plasma. Analytes in the ng/mL range are measurable with good reproducibility with intra- and interassay CVs of less than 5% to 10%. "Sandwich" methods have been developed for von Willebrand factor (plasma concentration about 8 micrograms/mL, Factor IX (5 micrograms/mL), protein C (4 micrograms/mL), and Factor X (10 micrograms/mL). However, this technique is only suitable for macromolecules; for low-molecular-mass peptides such as fibrinopeptide A a competitive method is used. Normal concentrations of fibrinopeptide A are below 3 ng/mL, with greater values suggesting in vivo generation of thrombin; thus this test is quite useful in detecting thrombosis. Reagents for both the sandwich and competitive methods are commercially available and cost effective, and have a longer shelf-life than those for radioimmunoassays.
Comparison of the Nancy Index With Continuous Geboes Score: Histological Remission and Response in Ulcerative Colitis
Authors: Magro Fernando , Lopes Joanne , Borralho Paula , Dias Cláudia Camila , Afonso Joana , Ministro Paula , Santiago Mafalda , Geboes Karel , Carneiro Fátima ,   Portuguese IBD Study Group [GEDII], Lopes Susana , Coelho Rosa , Cotter José , de Castro Francisca Dias , de Sousa Helena Tavares , Salgado Marta , Andrade Patrícia , Vieira Ana , Figueiredo Pedro , Caldeira Paulo , Sousa A , Duarte Maria , Ávila Filipa , Silva João , Moleiro Joana , Mendes Sofia , Giestas Sílvia , Sousa Paula , Gonçalves Raquel , Gonçalves Bruno Moreira , Oliveira Ana Maria , Chagas Cristina 
Published: January 2020

Abstract

Background and Aims
Evidence has been supporting that histological activity of ulcerative colitis [UC] has relevance for the prediction of clinical outcomes in UC patients, such as clinical relapse. In this study, we aimed to compare two histological indexes—the continuous Geboes score [GS] and the Nancy index [NI] —regarding their definitions of histological remission and response, and to determine the ability of faecal calprotectin [FC] levels to discriminate between these histological statuses according to the NI.

Methods
A large cohort of UC patients [N = 422] who were previously enrolled in other studies was analysed.

Results
GS and NI were shown to be strongly correlated [correlation coefficient: 0.882, p &lt;0.001], indicating high accordance in the classification of patients as having/not having histological remission and response. FC levels moderately correlated with NI regarding these histological statuses [correlation coefficient: 0.481, p &lt;0.001], moderately predicted the absence of remission defined by NI &gt;0 {area under the curve (AUC) 0.667 (95% confidence interval [CI] 0.609–0.724)}, and were good predictors of the absence of histological response defined by NI &gt;1 (AUC 0.825 [95% CI 0.777–0.872]). The optimal FC cut-offs determined to predict the NI-defined histological remission and response were 91 μg/g and 106 μg/g, when maximising the negative predictive value [NPV].

Conclusions
Due to the higher applicability of the NI, this study encourages the systematic use of this histological index to assess histological remission and response in UC patients.