bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved receptor assay for measuring digoxin activity.
Authors: Bednarczyk B , Soldin S J , Gasinska I , D'Costa M , Perrot L 
Published: January 2020

Abstract
We describe a receptor assay of digoxin activity involving Na+/K+-ATPase (EC 3.6.1.37) derived from human heart tissue. The procedure requires 500 microL of serum or plasma and incorporates one purification step, with Sep-Pak C18 cartridges (Waters). The method appears to be considerably more specific for digoxin and its cardio-active metabolites than are conventional immunoassays. Cardio-inactive metabolites and several digoxin-like factors cross react only slightly. The between-day coefficient of variation for the procedure ranged from 8.10% to 1.37% for digoxin concentrations between 0.5 and 5.0 nmol/L.
Colorimetry of p-aminohippurate in the presence of sulfamethoxazole.
Authors: Preuss H G , Razavi M H , Slemmer D , Zein M 
Published: January 2020

Abstract
Colorimetric quantification of p-aminohippurate (PAH), which is helpful in assessment of renal function, is subject to interference from sulfa compounds such as sulfamethoxazole. We were unable to measure serum PAH in two patients receiving a trimethoprim-sulfamethoxazole combination because of interference by the latter with the colorimetric estimation. We found that isoamyl acetate removes sulfamethoxazole from the samples without influencing PAH. The extraction is simple, inexpensive, and reproducible.
Macroamylasemia with a markedly increased amylase clearance ratio in a patient with renal cell carcinoma.
Authors: Kazmierczak S C , Van Lente F , McHugh A M , Katzin W E 
Published: January 2020

Abstract
We report hyperamylasemia, macroamylasemia, and a markedly increased amylase clearance/creatinine clearance ratio in a patient with renal cell carcinoma. Serum amylase activity was characterized as macroamylase by gel exclusion chromatography. Electrophoretic separation revealed an atypical band of amylase, migrating anodal to the S2 control fraction. Electrophoresis of urine revealed the presence of both S1 and S2 fractions, but not the atypical band found in serum. Quantification of the salivary- and pancreatic-type amylase fractions showed amylase in urine to be 100% salivary. Immunofixation disclosed the macroamylase to consist of an immune complex between amylase and IgA-lambda antibody. Binding-capacity studies showed that the serum immunoglobulin was present in excess and could bind 46% and 49% additional S-type amylase activity derived from saliva and the patient's urine, respectively. The amylase clearance/creatinine clearance ratio was markedly supranormal (0.134), unexpected in a patient with macroamylasemia. A biopsy specimen of the renal cell tumor was found to contain significant salivary-type amylase activity. These results suggest production of amylase by tumor tissue in the renal carcinoma and secretion of S-type amylase into the patient's urine. Evidently, macroamylase should be confirmed by gel exclusion chromatography.
Simultaneous determination of catecholamines and serotonin by liquid chromatography, after treatment with boric acid gel.
Authors: Imai Y , Ito S , Maruta K , Fujita K 
Published: January 2020

Abstract
We describe a liquid-chromatographic method for simultaneously determining norepinephrine, epinephrine, dopamine, and serotonin in 0.5 mL of human plasma. These analytes are purified on boric acid gel from Aldrich, separated on a reversed-phase C18 column, and detected electrochemically at +600 mV. Absolute recoveries of internal standards were 84% for 3,4-dihydroxybenzylamine and 57% for N-methylserotonin. Reproducibility was good to excellent, depending on the concentration of the analytes. A chromatographic run is complete in 40 min, but this can be shortened by about half when the determination of only serotonin is required, by increasing the column temperature from 40 degrees C to 60 degrees C.
Measurement of cholesterol in serum by gas chromatography/mass spectrometry at moderate mass resolution, with a nonendogenous cholesterol isomer as internal standard.
Authors: Kinter M , Herold D A , Hundley J , Wills M R , Savory J 
Published: January 2020

Abstract
We describe a gas chromatography/mass spectrometry method for the quantitative analysis of cholesterol in serum. A structural isomer of cholesterol, 7,(5 alpha)-cholesten-3 beta-ol, is used as an internal standard, its primary advantage being its lesser cost relative to that of a stable-isotope-labeled analog. Analysis of the National Bureau of Standards Certified Reference Serum (SRM 909) was used to validate the method. The results show this method to be highly accurate (bias = -0.6%) and precise (CV = 1.6% between-run, 1.2% within-run). The performance of this method is, therefore, sufficiently good to allow its use as a reference method for determinations of cholesterol in serum.
Cis-4-decenoic acid in plasma: a characteristic metabolite in medium-chain acyl-CoA dehydrogenase deficiency.
Authors: Duran M , Bruinvis L , Ketting D , de Klerk J B , Wadman S K 
Published: January 2020

Abstract
The profile of organic acids in plasma of patients with a deficiency of medium-chain acyl-CoA dehydrogenase (EC 1.3.99.3) was determined by gas-liquid chromatography of trimethylsilylated derivatives of the acids isolated by ethyl acetate extraction. All 13 patients had increased concentrations of free octanoate, cis-4-decenoate, and decanoate in their plasma. Cis-4-decenoate, an intermediary metabolite of linoleic acid, is pathognomonic of medium-chain acyl-CoA dehydrogenase deficiency. This metabolite does not accumulate in plasma after oral loading with medium-chain triglycerides, in contrast to octanoate and decanoate. Two postmortem plasma samples from victims of infant sudden-death syndrome had detectable octanoate and decanoate, but cis-4-decenoate could not be detected. The identification of cis-4-decenoate in plasma may be an aid in the diagnosis of an inherited defect in oxidation of medium-chain fatty acids.
Changes in the concentration of testosterone in serum during the menstrual cycle, as determined by liquid chromatography.
Authors: Oka K , Hirano T , Noguchi M 
Published: January 2020

Abstract
We used a newly developed high-performance liquid chromatographic (HPLC) method to determine the concentration of testosterone in serum from women and compared the results with those obtained by conventional radioimmunoassay. We used a conventional silica gel column and organic solvent mixture (ethanol plus n-hexane containing a small amount of water). The detection limit for testosterone was as low as 0.2 micrograms/L, sufficient to correctly determine the concentration of the hormone in serum from women. For the calibration curve, we plotted the peak-height ratio of testosterone to 19-nortestosterone. The menstrual-cycle-related rhythm of the concentration of testosterone in serum was related to follicular and luteal phase-shifting, the concentration being considerably greater in the luteal phase than in the follicular phase. In contrast, RIA showed only minor and irregular fluctuation in the concentrations of the hormone throughout the menstrual cycle. When we used the HPLC to measure the hormonal change in a woman with an irregular menstrual cycle, we found that her testosterone concentration increased abnormally early after menstruation.
Immunoprecipitation method for CK-MB analysis re-evaluated: influence of CK-BB and macro-CK on blank activities.
Authors: Jacobs E , Anzalone T , Sarkozi L 
Published: January 2020

Abstract
We evaluated the analytical performance of the immunoprecipitation technique for quantification of creatine kinase (CK; EC 2.7.3.2) isoenzyme MB, focusing on specimens with increased blank activities. The samples we studied had blank values that were equal to or greater than either 15 U/L or the uncorrected CK-MB value. Of 134 specimens selected, 16 and 21 contained macro CK type 1 and CK-BB, respectively. All samples containing macro CK type 1 gave negative CK-MB values, even though four contained significant quantities of CK-MB. Correcting the blank value for the fluid displacement of the second antibody suspension eliminated all but three of the negative results. However, 45 specimens, negative for CK-MB by electrophoresis, gave CK-MB values ranging from 1 to 21 U/L. Furthermore, 11 of the specimens containing macro-CK type 1 were in this group. Thus, the presence of macro-CK type 1 definitely interferes with the immunoprecipitation technique. Our results indicate the need to re-evaluate the diagnostic accuracy of the immunoprecipitation technique, especially when the un-adjusted blank activities are increased.
Renal clearance of pancreatic and salivary amylase relative to creatinine clearance in patients with renal disease and proteinuria.
Authors: Wetzels J F , Hafkenscheid J C , Hessels M , Hoitsma A J , Koene R A 
Published: January 2020

Abstract
To study the charge-selective properties of the glomerular filter in renal disease, we measured the fractional clearance, relative to creatinine clearance (ECC), of the amylase isoenzymes pancreatic amylase and salivary amylase, which have identical size but different charge. In 63 healthy subjects the mean (and SD) fractional excretion of pancreatic amylase, 4.07% (1.24%), was fourfold that of salivary amylase: 1.02% (0.54%). For 29 patients with renal disease and proteinuria, the mean fractional excretion of pancreatic amylase was significantly lower, 3.31% (1.94%), and that of salivary amylase significantly higher, 2.06% (1.41%), than in controls. In these patients, fractional excretions of both these isoenzymes were negatively correlated with urinary excretion of beta 2-microglobulin and ECC. Evidently, differences in clearances of pancreatic and salivary amylase are a consequence of differences in charge-related glomerular filtration. The relative increase of salivary amylase clearance in patients with renal disease and proteinuria is most probably caused by a loss of the charge-selective properties of the glomerular basement membrane.
Legal issues related to drug testing in the clinical laboratory.
Authors: Chamberlain R T 
Published: January 2020

Abstract
As has been reported many times by the lay press, urine drug testing may pose some unique challenges. The clinical laboratory interested in industrial drug testing (typically known as employee drug testing) should be aware of the many challenges that may be brought on by the fact that the result may be contested in an adversarial proceeding. This is what makes the urine drug test a forensic test. It may be one piece of evidence or the only piece of evidence used in an adversarial proceeding that may decide on punitive or rehabilitative action against an employee. As a result, unique standards for governmental contract laboratories have been proposed from the National Institute on Drug Abuse, and special proficiency testing and accreditation procedures have been promoted by professional societies. These standards illustrate the sensitive nature of the results. Because the results are subject to adversarial proceedings, all parties concerned in the testing process should be aware of the legal issues surrounding urine drug testing. There are constitutional and statutory issues as well as tort issues such as negligence, defamation, invasion of privacy, battery, infliction of emotional distress, and others. Laboratories should be especially aware of these issues, since they may be brought in as a third-party defendant to a suit or brought in as a participant in gathering the evidence. The laboratory should also be aware of other legal ramifications such as chain of custody, expert testimony, and the acceptability of scientific evidence.
Total lactate dehydrogenase and its isoenzymes in serum of patients with non-small-cell lung cancer.
Authors: Rotenberg Z , Weinberger I , Sagie A , Fuchs J , Davidson E , Sperling O , Agmon J 
Published: January 2020

Abstract
Values for total lactate dehydrogenase (LD, EC 1.1.1.27) activity in serum and LD isoenzymes were determined at diagnosis in 273 patients with non-small-cell lung cancer, 85 of whom were in stage 1, 92 in stage 2, and 96 in stage 3. We divided the patients into three groups, based on their total serum LD values: less than 225 U/L (normal reference range), 226-500 U/L, and greater than 500 U/L. Overall values for LD were above normal at diagnosis for 69% of the patients, being moderately increased in 63 patients and highly increased in 125. Eighty percent of the patients in stage 1 had normal values for LD at diagnosis, but 88% of the patients in stage 2 and 94% of the patients in stage 3 had above-normal LD values at diagnosis. In 55% of the patients in stage 2 and 73% of the patients in stage 3, LD activity was highly increased. In the patients with normal values for total LD, the proportions of the LD isoenzymes were normal. In the patients with increased LD, the isoenzyme proportions were increased for LD-4 and LD-5, up to twice the normal values. The sensitivity of LD in detection of lung cancer was 60% for LD at the cutoff point of 250 U/L in comparison with normal controls, and 47% for LD at the cutoff point of 310 U/L in comparison with the benign lung disease group of patients (95% specificity). We conclude that total LD in serum may be a direct indicator of clinical stage and tumor burden in patients with non-small-cell lung cancer.
Midazolam in plasma from hospitalized patients as measured by gas-liquid chromatography with electron-capture detection.
Authors: Ha H R , Funk B , Maitre P O , Zbinden A M , Follath F , Thomson D A 
Published: January 2020

Abstract
The present assay was developed for quantifying midazolam in plasma of patients hospitalized in intensive-care units or undergoing anesthesia and receiving many other drugs as well. Plasma samples are alkalinized with NaOH and midazolam is extracted into n-hexane. The organic phase is evaporated and reconstituted in n-butyl acetate, and the midazolam is quantified by gas-liquid chromatography with electron-capture detection. The calibration graph for midazolam was linear in the ranges 5-200 and 200-800 micrograms/L. The CVs for precision and reproducibility of the assay were less than 8%. The method was very specific for midazolam; most of the drugs commonly used in anesthesia and in the intensive-care unit did not interfere with the assay. The lowest detectable concentration was 1 microgram/L. The method is adaptable for use with an automated chromatographic system.
Simultaneous determination of four monoamine metabolites and serotonin in cerebrospinal fluid by "high-performance" liquid chromatography with electrochemical detection; application for patients with Alzheimer's disease.
Authors: Koyama E , Minegishi A , Ishizaki T 
Published: January 2020

Abstract
We describe an optimized, sensitive assay procedure for simultaneously determining 3-methoxy-4-hydroxyphenylglycol, 3,4-dihydroxyphenylacetic acid, and serotonin in human lumbar cerebrospinal fluid. The assay is based on liquid chromatography with an electrochemical detection system equipped with a newly developed, highly sensitive graphite electrode. Before assay, samples are deproteinized with perchloric acid, 0.2 mol/L. The within- and between-day CVs were less than 2.5% and 6.7%, respectively, for all compounds. The lower limits of detection for 3-methoxy-4-hydroxyphenylglycol and 3,4-dihydroxyphenylacetic acid were 0.5 pg and for the other three analytes 1.5 pg per injection. Preliminary data on monoaminergic metabolites by the current assay showed that concentrations of dopaminergic and serotonergic metabolites were significantly (P less than 0.05) lower in patients with Alzheimer's disease than in the age-matched controls. In addition, the concentration of 3,4-dihydroxyphenylacetic acid correlated significantly (P less than 0.01) with that of homovanillic acid, suggesting that monitoring either of these metabolites in cerebrospinal fluid can be used as an index of central dopaminergic activity.
Total, tartrate-resistant, and tartrate-inhibited acid phosphatases in serum: biological variations and reference limits.
Authors: Schiele F , Artur Y , Floc'h A Y , Siest G 
Published: January 2020

Abstract
We studied several factors affecting biological variation in serum acid phosphatases in a population of 1195 apparently healthy subjects four years old or older. We assayed total acid phosphatase activities in the presence of a transphosphorylating agent and using alpha-naphthyl phosphate as substrate. The main factors modifying total and tartrate-resistant acid phosphatases activities in serum are similar to those observed for total and bone alkaline phosphatases activities: age, sex, and hormonal state (puberty or menopause). The tartrate-inhibited acid phosphatase activity is, however, independent of biological variations. Finally, we propose reference limits for total, tartrate-resistant, and tartrate-inhibited acid phosphatases in serum.
Thyroxin binding by human serum albumin after denaturation of the thyroxin-binding globulin in familial dysalbuminemic hyperthyroxinemia.
Authors: Arevalo G 
Published: January 2020

Abstract
Abnormal binding of thyroxin (T4) to serum albumin of subjects with familial dysalbuminemic hyperthyroxinemia (FDH) is generally demonstrated by the T4-loaded charcoal uptake test, with T4 added in excess (0.1 mmol/L) to accentuate T4 binding to albumin in FDH. I describe a binding study involving T4 tracer in which thyroxin-binding globulin is denatured in samples by treatment with mild acid at pH less than 3.0. The tracer is bound to the serum albumin and, to a greater extent, to the FDH albumin, because the binding by thyroxin-binding prealbumin is blocked by barbital buffer. The result of the [125I]T4 binding to the albumin is expressed as a T4 binding index, based on results for pooled sera from patients with normal thyroid function as a reference. The mean index in FDH was 4.08 (SD 0.92, n = 5); in hypoalbuminemia, 0.66 (SD 0.18, n = 8); in normal subjects, 1.00 (SD 0.11, n = 20). This albumin-binding index enables the rapid and unequivocal diagnosis of subjects with FDH, without the addition of unlabeled T4.
Micro-scale two-dimensional electrophoresis of alkaline phosphatase from serum.
Authors: Sanderink G J , Artur Y , Paille F , Galteau M M , Siest G 
Published: January 2020

Abstract
Isoenzymes of alkaline phosphatase (EC 3.1.3.1) were separated by micro-scale two-dimensional electrophoresis, with isoelectric focusing in capillary gels in the first dimension and polyacrylamide gradient-gel electrophoresis in the second. The isoenzymes detected were identified by several treatments--e.g., incubation with sialidase, papain, Triton X-100, and wheat-germ agglutinin--and by comparison with alkaline phosphatase from liver microsomes. Liver and bone isoforms in normal sera showed overlapping isoelectric points but differed in molecular mass, estimated as 172 and 185 kDa, respectively. Sera of patients with liver disease showed several additional groups of alkaline phosphatase isoforms, two of which were found to consist of multi-molecular complexes. Others probably correspond to incompletely glycated enzyme proteins. A further isoform with a mass of about 250 kDa does not seem to correspond to any known isoform of alkaline phosphatase in serum. With this technique, we demonstrated intra- and interindividual variations of the placental alkaline phosphatase isoenzyme in pregnancy sera.
Reversible loss of lactate dehydrogenase isoenzymes and lactate dehydrogenase activity in patient's serum.
Authors: Kraaijenhagen R J , Backer E T 
Published: January 2020

Abstract
An abnormal lactate dehydrogenase (LD; EC 1.1.1.27) electrophoretogram (only one band, at the application site) and a low LD activity (7 U/L) was seen for a patient's serum during storage at 22 and 4 degrees C. Both reverted to normal when the serum was incubated at 37 degrees C.
Medicolegal alcohol determination: Widmark revisited.
Authors: Simpson G 
Published: January 2020

Abstract
Several concepts and principles advanced by Widmark over 50 years ago are briefly compared with results of recently published experimental work. His conclusions--that breath alcohol analysis can lead to overestimates of actual blood alcohol concentration, and that +/- 2 standard deviations about the average should be used to estimate certain pharmacokinetic parameters for medicolegal alcohol determinations--are supported by these more-recent experimental results.
Valproic acid and the liver.
Authors: Cotariu D , Zaidman J L 
Published: January 2020

Abstract
Valproic acid (VPA) is widely used as an anticonvulsant, but therapy with the drug has been associated with hepatotoxicity, either reversible hepatic dysfunction or irreversible hepatic failure. Both clinical and experimental studies have revealed several VPA-related biochemical abnormalities in the liver: inhibition of the beta-oxidation and synthesis of fatty acids and inhibition of gluconeogenesis, urea synthesis, oxidative phosphorylation, and the glycine cleavage system. Other abnormalities noted include alteration in the protein conformation of the internal mitochondrial membrane, hyperammonemia, and increased bile flow. The mechanisms of such hepatotoxicity, whether mediated by VPA or by its metabolites, are still little understood. Susceptibility to VPA hepatotoxicity may be enhanced by such conditions as starvation, inborn errors of metabolism, additional neurological disease, and concomitant administration of enzyme-inducing drugs.
Creatine kinase MB in cases of skeletal muscle trauma.
Authors: Schwartz J G , Prihoda T J , Stuckey J H , Gage C L , Darnell M L 
Published: January 2020

Abstract
Fifty-eight patients admitted through our emergency room with severe skeletal muscle injury but no obvious cardiac contusions were evaluated for creatine kinase isoenzyme MB (CK-MB). When such patients show an above-normal value for total CK, it is a question of whether or not myocardial injury has been sustained along with skeletal muscle injury when (a) there are no obvious chest contusions or (b) the patient is unconscious and unable to complain of chest pain. Whenever there is doubt concerning the cardiac status of a patient, lactate dehydrogenase (LD) isoenzymes, serial electrocardiograms, and CK isoenzymes are ordered. Our study revealed that serum of 8.6% of the trauma victims had CK-MB values exceeding 5.0 EU/L (reflecting abnormal CK-MB concentrations) as part of their increased total CK. All patients had normal electrocardiographic patterns along with negative results for LD isoenzymes; none had sustained any demonstrable myocardial injury. The CK-MB value must be interpreted together with the total CK value for appropriate diagnosis in patients with skeletal muscle trauma.
Interference of fetal hemoglobin with the spectrophotometric measurement of carboxyhemoglobin.
Authors: Vreman H J , Ronquillo R B , Ariagno R L , Schwartz H C , Stevenson D K 
Published: January 2020

Abstract
We measured the concentration of carboxyhemoglobin (HbCO) in blood samples from 32 neonates by spectrophotometry (IL282 CO-Oximeter) and gas chromatography, finding a strong positive correlation (r = 0.89) between the concentration of fetal hemoglobin (Hb F) and HbCO as measured by spectrophotometry, but not by gas chromatography. Thus, Hb F interferes with the determination of HbCO by spectrophotometric techniques by falsely increasing apparent HbCO in direct proportion to Hb F. We conclude that, when Hb F is known or suspected to be present, blood HbCO cannot be reliably determined by methods based on spectrophotometry.