bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serum and Tissue Carnitine Assay Based on Dialysis
Authors: Shihabi Z K , Oles K S , McCormick C P , Penry J K 
Published: January 2020

Abstract
Carnitine (L-beta-hydroxy-gamma-trimethylaminobutyric acid) aids mitochondrial energy production by transferring fatty acids across the membranes for beta-oxidation. We describe here a modified enzymatic assay for free serum and tissue carnitine based on dialysis to remove interfering substances in the serum, with subsequent conversion of carnitine to the acyl derivative by carnitine acetyltransferase (EC 2.3.1.7) in the presence of 5,5'-dithiobis-(2-nitrobenzoic acid). The method compared well with a radioenzymatic assay. The reference interval for serum is 28-70 mumol/L. Patients with advanced diabetes and those undergoing valproic acid treatment displayed lower mean values; a statistically significant number of them showed serum carnitine values below the reference interval. The method was also applied to carnitine measurement in cerebrospinal fluid and human tissues.
Hemoglobin A1C by Hplc with the Pharmacia Mono S HR 5/N Cation-Exchange Column: Influence of Sample Protein Load on Optimal Chromatographic Conditions
Authors: Philcox J C , Haywood M R , Rofe A M 
Published: January 2020

Abstract
The Pharmacia Mono S HR 5/5 column has been optimized for hemoglobin A1c analysis by HPLC by using a much smaller column load, decreased buffer flow rate, and a steeper gradient than was used in previously described methods. Superior chromatographic separation, shorter analysis time, and a greatly extended column life have resulted.
Simultaneous Measurement of Cortisol in Serum and Saliva After Different Forms of Cortisol Administration
Authors: Tunn S , Möllmann H , Barth J , Derendorf H , Krieg M 
Published: January 2020

Abstract
To prove the clinical usefulness of cortisol measurements in saliva for the exact assessment of a patient's corticoid status under therapeutic hormone substitution, we measured simultaneously total cortisol in serum and non-protein-bound cortisol in saliva after administration of different forms of hydrocortisone (cortisol) in eight cortisol-suppressed, healthy male volunteers. The intravenous and oral administration of 20 mg of cortisol exceeds the binding capacity of the corticosteroid-binding globulin (CBG), leading to an increase of the ratio between salivary and serum cortisol at the higher cortisol concentrations in blood. After rectal administration of 100 mg of cortisol acetate, the serum cortisol concentration does not exceed the binding capacity of CBG, so the ratio between salivary and serum cortisol remains nearly constant. However, this ratio was higher after rectal administration than after intravenous and oral administration, probably because of weaker binding of the acetate form of cortisol to CBG. Thus, the salivary measurement of the non-protein-bound (i.e., biologically active) cortisol offers a convenient way to monitor the effectiveness of various forms of systemic corticoid substitution.
First Practical Colorimetric Assay of Lithium in Serum
Authors: Chapoteau E , Czech B P , Zazulak W , Kumar A 
Published: January 2020

Abstract
We report a colorimetric method for determining lithium in blood serum without sample pretreatment or solvent-extraction steps. The method is based on a novel chromogenic ionophore that exhibits exceptionally high selectivity (much greater than 4000:1) for lithium over sodium. The standard curve for the method is linear up to 3.5 mmol/L and exceeds the therapeutic range for lithium. The results for 57 patients' samples correlated well with results obtained with an Instrumentation Laboratory flame photometer (r = 0.97).
A Simplified Procedure for Eliminating the Negative Interference of Bilirubin in the Jaffé Reaction for Creatinine
Authors: O'Leary N , Pembroke A , Duggan P F 
Published: January 2020

Abstract
The negative interference by bilirubin in the measurement of creatinine by the Jaffé procedure is well documented. We describe a procedure for the elimination of interfering bilirubin by oxidation to biliverdin through the addition of potassium ferricyanide before the alkaline picrate reagent. We detected no negative interference with the addition of as much as 600 mumol/L bilirubin. The procedure shows good agreement with a recently described blank rate method for analyzing icteric samples.
Albuminuria in People At Least 40 Years Old: Effect of Obesity, Hypertension, and Hyperlipidemia
Authors: Metcalf P , Baker J , Scott A , Wild C , Scragg R , Dryson E 
Published: January 2020

Abstract
Concentrations of urinary albumin and the albumin:creatinine ratio were measured in early-morning urine specimens from 5670 people older than 40 years who participated in a health screening survey of a local workforce. Sex-specific reference intervals were determined in a subgroup of 3597 people after excluding 2073 individuals with Albustix-positive proteinuria; diabetes mellitus; bacteriuria; current hypertension; body mass index greater than or equal to 30 kg/m2; or serum triglyceride greater than or equal to 2.5 mmol/L. The 97.5 percentile concentration for urinary albumin was 28 mg/L in men and 29 mg/L in women; for the albumin:creatinine ratio this was 2.3 g/mol in men and 2.8 g/mol in women. In the study population, the degree of albuminuria showed piecewise log-linear relationships with diastolic blood pressure (P = 0.0001) and body mass index (P = 0.0001), log-linear relationships with hypertriglyceridemia (P = 0.0001) and hypercholesterolemia (P = 0.0001), and a negative piecewise linear relationship with high-density lipoprotein (HDL) cholesterol (P = 0.0461).
Equilibrium Model for Speciation of Aluminum in Serum
Authors: Harris W R 
Published: January 2020

Abstract
An equilibrium model for the speciation of Al3+ in normal serum has been developed in which 81% of the aluminum is bound to transferrin. The remaining 19% exists primarily as Al(PO4)(OH)-, with minor amounts of citrate and hydroxide species. The model meets several key criteria. The concentration of free aluminum is below the upper limit set by the solubility product of aluminum phosphate. The fraction of low-molecular-mass aluminum species agrees with experimental studies on the fraction of ultrafiltrable aluminum in both normal and uremic serum. Lastly, the model accounts for the relative effectiveness of EDTA, citrate, and desferrioxamine B for binding aluminum in serum by including competition from zinc, magnesium, and calcium for these ligands. Uncertainties in the available thermodynamic database are discussed.
Low Ratio of Androstenedione to Testosterone in Plasma and Saliva of Hirsute Women
Authors: Swinkels L M , van Hoof H J , Ross H A , Smals A G , Benraad T J 
Published: January 2020

Abstract
To gain insight into the passage of androstenedione (A4) through the salivary gland, we measured concentrations of plasma total (TA4), free (FA4), and salivary (SA4) androstenedione during administration of dexamethasone and synthetic corticotropin to control subjects and hirsute women and compared these data with plasma total (TT), free (FT), and salivary testosterone (ST) concentrations. TA4 and FA4 were significantly lower in control subjects throughout (0, 15, 45, and 75 min) (P less than 0.05). SA4 in control subjects was significantly lower only in the follicular phase at 0 and 15 min. There was no significant difference between the increments in SA4 in response to corticotropin. The concentration of SA4 in the control women at 0 min was not significantly different from the concentration of FA4. At 45 and 75 min after corticotropin administration, however, SA4 was slightly higher than FA4 (P less than 0.01). In hirsute women, however, the concentration of SA4 was significantly lower than FA4 at all times (P less than 0.05). TT, FT, and ST concentrations were about twofold higher in the hirsute women than in control subjects throughout. In both groups, ST concentrations were three times as high as FT concentrations (P less than 0.001). The SA4:ST ratio was significantly lower than the FA4:FT ratio in both groups (P less than 0.001) because of higher ST than FT concentrations and similar or even lower SA4 concentrations in both groups. Both FA4:FT and SA4:ST ratios were lower in hirsute women, except for the FA4:FT ratio in control subjects in the luteal phase. Our data are compatible with 17-hydroxysteroid oxidoreductase activity in the salivary gland. If the difference in the ratios of A4 to T between hirsute women and control subjects is attributed to this hypothetical enzymatic activity, it would suggest a more rapid conversion of A4 to T in the hirsute group.
Immunochemical Detection of Group I and Group II Phospholipases A2 in Human Serum
Authors: Nevalainen T J , Kortesuo P T , Rintala E , Märki F 
Published: January 2020

Abstract
Time-resolved fluoroimmunoassay was developed for the detection of synovial-type phospholipase A2 (s-PLA2) in human serum. This solid-phase, sandwich assay uses a polyclonal rabbit antibody raised against synovial-type group II PLA2 produced in Escherichia coli. No cross-reactions were detected between s-PLA2 and PLA2 from human or porcine pancreas, human ascitic fluid, or bee or cobra venom. In healthy individuals, the average concentration of s-PLA2 is 3.7 micrograms/L, with a 95% reference interval from 1.3 to 10.8 micrograms/L. We investigated pancreatic PLA2, which is a group I PLA2, and synovial-type group II PLA2 in sera of patients with hematological malignancies and septic fever. The concentration of s-PLA2 was increased in patient sera and correlated significantly with the catalytic activity of PLA2 and the concentration of C-reactive protein. No correlation with the concentration of pancreatic PLA2 was found. The results suggest that the increased catalytic activity of PLA2 in sera of patients with septic fever results from synovial-type group II PLA2.
Sex- and Race-Related Differences in Liver-Associated Serum Chemistry Tests in Young Adults in the Cardia Study
Authors: Manolio T A , Burke G L , Savage P J , Jacobs D R , Sidney S , Wagenknecht L E , Allman R M , Tracy R P 
Published: January 2020

Abstract
Simultaneous multiple automated analyses of liver function can be performed quickly and cheaply, but their usefulness in mass screening is questionable. Reference intervals are frequently applied without regard to race and sex, despite the fact that reported values may vary considerably in relation to these factors. Serum analyte results for greater than 5000 black and white men and women in the CARDIA Study showed clinically and statistically significant differences by race and sex for values of aspartate aminotransferase, gamma-glutamyltransferase, alkaline phosphatase, total bilirubin, total protein, and albumin; these differences were not explained by differences in age, body mass, reported ethanol intake, smoking, or oral contraceptive use. Results for at least one of these six tests were out of range in 38% of the men and 19% of the women. Sex- and race-specific reference intervals are recommended to decrease the frequency of values reported as abnormal in otherwise healthy young adults.
Effect of Freezing and Thawing of Serum on the Immunoassay of Lipoprotein(a)
Authors: Sgoutas D S , Tuten T 
Published: January 2020

Abstract
We studied the effect of freezing and thawing of serum on the determination of lipoprotein(a) [Lp(a)] with a commercial enzyme-linked immunosorbent assay (ELISA) and an immunoturbidimetric assay (ITA). Portions of sera from 11 apparently healthy persons and pooled sera, from an additional 10 subjects were frozen at either -20 or -70 degrees C and thawed at room temperature. Cycles of freezing and thawing were repeated during the experiments (1 month). Samples were assayed for Lp(a) after thawing. Pooled sera were subjected to quick freezing at -70 degrees C and thawing at room temperature in cycles. Results show a significant (P less than 0.05) decrease in Lp(a) concentration in sera subjected to freezing and thawing. Samples thawed from -20 degrees C gave concentrations by ELISA that were significantly lower than those of fresh samples after one freeze-thaw cycle. By ITA the decrease was significant only after two cycles. In specimens frozen at -70 degrees C, Lp(a) concentrations determined by ELISA decreased after two cycles, and by ITA after three freeze-thaw cycles. Serum samples subjected to quick freezing at -70 degrees C and thawing did not show significant decreases in Lp(a) immunoreactivity during four cycles. Immunoreactivity of Lp(a) in samples stored at 4 degrees C decreased after 6 days but fell faster in serum samples subjected to freezing and thawing before storage at 4 degrees C.
Effect of pH and Citrate on Binding of Iron and Gallium by Transferrin in Serum
Authors: McGregor S J , Brock J H 
Published: January 2020

Abstract
Although both Al and Fe are bound to transferrin in plasma, they are metabolized differently. Aluminum is less tightly bound to transferrin than is Fe, and might be released in circumstances in which Fe remains bound. The effect of pH ana citrate on the binding of 67Ga (a radiotracer used as an analog of Al) to transferrin in normal human serum was tested in the presence of physiological concentrations of CO2. At pH less than 6.8, Ga started to dissociate from transferrin; at pH 6, greater than 50% of the added 67Ga was present in a low-M(r) form. In contrast, almost all Fe remained bound to transferrin at pH values as low as 4.7. Citrate at concentrations as great as 100 mmol/L had no effect on binding of Fe, but the binding of 67Ga was markedly reduced at citrate greater than 1 mmol/L. Being bound to transferrin less strongly than Ga is, Al could dissociate even more readily, and loss of Al from transferrin in the kidney might explain why Al but not Fe is excreted in urine.
Biochemical markers for detecting bone metastases in patients with breast cancer
Authors: Moro L , Gazzarrini C , Crivellari D , Galligioni E , Talamini R , de Bernard B 
Published: January 2020

Abstract
A study was carried out to assess the best use of biochemical bone markers to exclude metastases in patients with breast cancer. Urinary galactosyl-hydroxylysine and serum alkaline phosphatase were used to monitor bone resorption and deposition, respectively. Hydroxyproline was also measured. In a selected population of patients, possibly affected by metastases on the basis of scintigraphic examination, which is highly sensitive but poorly specific, we assessed the efficiency of the markers by a double statistical analysis. In this group, the only marker able to predict metastases was galactosyl-hydroxylysine.
Plasma and urinary oxalate and glycolate in healthy subjects
Authors: Hagen L , Walker V R , Sutton R A 
Published: January 2020

Abstract
High-performance ion chromatography (HPIC) has been widely used for oxalate analysis and, more recently, for glycolate analysis. We describe a procedure for sample preparation in which the plasma ultrafiltrate is acidified during harvesting with a cation-exchange resin, and the chloride is removed before the ion chromatography, which is performed with a newly developed AS10 column. The same ultrafiltrate sample is analyzed for glycolate. For plasma oxalate, the mean recovery of sample in eluted fractions was 95-96%, and intraassay CV was 6.2-8.1%. The reference interval (mean +/- 2 SD) for men was 0.8-3.2 mumol/L and for women, 1.0-2.6 mumol/L. For urinary oxalate, the reference interval for men was 175-560 mumol/day and for women, 107-432 mumol/day. For plasma glycolate, the mean analytical recovery was 96-98%, and the intra-assay CV was 2.4-6.2%. The reference interval for men was 1.9-7.5 mumol/L and for women, 1.4-7.4 mumol/L. For urinary glycolate, the reference interval for men was 0-1400 mumol/day and for women, 91-1001 mumol/day.
Biliary and urinary neopterin concentrations in monitoring liver-allograft recipients
Authors: Hausen A , Aichberger C , Königsrainer A , Weiss G , Margreiter R , Wachter H 
Published: January 2020

Abstract
Biliary neopterin concentrations were measured daily in nine liver-transplant recipients during the early post-transplant period (on average, 25 days). Concentrations increased strongly during rejection episodes and decreased quickly after successful antirejection therapy. Contrary to the changes of urinary neopterin, cytomegalovirus infection and hepatitis were not associated with an increase in biliary neopterin concentrations. Therefore, measurement of neopterin in bile fluid and in urine may aid in distinguishing rejection from infectious complications in liver-allograft recipients.
Ionic binding, net charge, and Donnan effect of human serum albumin as a function of pH
Authors: Fogh-Andersen N , Bjerrum P J , Siggaard-Andersen O 
Published: January 2020

Abstract
The ionic activities and total molalities of sodium, potassium, calcium, lithium, and chloride in a solution of human serum albumin were measured at different values of pH between 4 and 9. The same quantities were measured simultaneously in a protein-free electrolyte solution in membrane equilibrium with the albumin solution. Taking the residual liquid-junction potential and bias from unselectivity of the electrodes into account, we determined the own, bound, and net charges of albumin. Chloride was amply bound at low pH, and calcium at high pH. The varying charge of ions bound to albumin opposed the effect of acid or base on the net charge. All ions were distributed across the membrane according to the same electric potential difference, which equalled the Donnan potential. The high concordance between observation and theory favors the Donnan theory and furthermore implies that the electrodes are as accurate in a solution with albumin as in a protein-free solution.
Rapid diagnosis of phenylketonuria by quantitative analysis for phenylalanine and tyrosine in neonatal blood spots by tandem mass spectrometry
Authors: Chace D H , Millington D S , Terada N , Kahler S G , Roe C R , Hofman L F 
Published: January 2020

Abstract
A new method for quantifying specific amino acids in small volumes of plasma and whole blood has been developed. Based on isotope-dilution tandem mass spectrometry, the method takes only a few minutes to perform and requires minimal sample preparation. The accurate assay of both phenylalanine and tyrosine in dried blood spots used for neonatal screening for phenylketonuria in North Carolina successfully differentiated infants who had been classified as normal, affected, and falsely positive by current fluorometric methods. Because the mass-spectrometric method also recognizes other aminoacidemias simultaneously and is capable of automation, it represents a useful development toward a broad-spectrum neonatal screening method.
Determination of metanephrines in plasma by liquid chromatography with electrochemical detection
Authors: Lenders J W , Eisenhofer G , Armando I , Keiser H R , Goldstein D S , Kopin I J 
Published: January 2020

Abstract
Metanephrines are O-methylated metabolites of catecholamines. We report the use of liquid chromatography with electrochemical detection to determine plasma concentrations of normetanephrine (NMN) and metanephrine (MN). Plasma NMN and MN in 32 normal volunteers and inpatients were compared with concentrations in 23 patients with pheochromocytoma. Metanephrines were adsorbed from plasma onto a cation-exchange column and eluted with ammoniacal methanol. The dried residue was dissolved in mobile phase and injected onto a reversed-phase column. Recoveries of NMN and MN from 1 mL of plasma averaged 50-70%, and results varied linearly with quantity injected over a range of 0.13-55 pmol. The detection limit was 25 fmol for NMN and 50 fmol for MN. Intra-assay CVs were &lt; 5%. In normal volunteers and inpatients, plasma concentrations of NMN ranged between 0.12 and 0.73 nmol/L (mean 0.38 nmol/L), and MN between 0.06 and 0.63 nmol/L (mean 0.19 nmol/L). Plasma NMN concentrations were increased in all 23 patients with pheochromocytoma (range 1-172 nmol/L), whereas MN concentrations (range 0.10-382 nmol/L) were increased in only 9 patients. The assay method is reliable and sensitive and offers an approach to examine the extraneuronal metabolism of catecholamines. The method may also be useful in the diagnosis of pheochromocytoma.
Urinary selenium concentrations
Authors: Sanz Alaejos M , Díaz Romero C 
Published: January 2020

Abstract
Urinary selenium concentrations are used as an indicator of selenium status. A strong correlation has been established between dietary selenium and daily urinary selenium excretion in a wide range of populations from all over the world with different dietary selenium intake. Data on urinary selenium concentrations in healthy individuals and patients with different pathological conditions are reviewed. Selenium excretion rates of 20-200 micrograms/day are not associated with deficiency or toxicity problems. Urinary Se excretion is decreased in children, elderly people, and pregnant women. Workers exposed to heavy metals, and cancer patients, have higher and lower urinary Se concentrations, respectively, than control groups. The trimethylselenonium ion, a minor metabolite of Se in urine, assumes a significant role only in the detoxification of excess Se intake. Studies of bioavailability and balance show the important role of the kidneys in homeostatic regulation of Se.
Interpretation of results for tumor markers on the basis of analytical imprecision and biological variation
Authors: Sölétormos G , Schiøler V , Nielsen D , Skovsgaard T , Dombernowsky P 
Published: January 2020

Abstract
Interpretation of results for CA 15.3, carcinoembryonic antigen (CEA), and tissue polypeptide antigen (TPA) during breast cancer monitoring requires data on intra- (CVP) and inter- (CVG) individual biological variation, analytical imprecision (CVA), and indices of individuality. The average CVP and CVG obtained from 22 healthy women were, respectively, 6.2% and 62.9% (CA 15.3), 9.3% and 86.8% (CEA), and 28.3% and 133% (TPA). The indices of individuality were all &lt; 0.6: 0.2 (CA 15.3), 0.15 (CEA), and 0.2 (TPA). CVA depended on the concentration of the analytes. CVP and CVA determine what constitutes a significant difference between sequential results. Assuming a CVA of 11.2% (CA 15.3), 9.5% (CEA), or 11.9% (TPA), results must differ by 30%, 31%, or 72%, respectively, for P &lt; or = 0.05. We found that CVP and CVA contribute considerably to the variation during breast cancer monitoring. Consequently, both CVP and CVA should be considered in criteria for marker evaluation. Because of low indices of individuality, conventional cutoff limits are inappropriate both for initial identification and for follow-up of breast cancer.
Fully automated assay of glycohemoglobin with the Abbott IMx analyzer: novel approaches for separation and detection
Authors: Wilson D H , Bogacz J P , Forsythe C M , Turk P J , Lane T L , Gates R C , Brandt D R 
Published: January 2020

Abstract
We describe a novel assay for measuring glycohemoglobin directly from anticoagulated whole blood with the Abbott IMx analyzer. The glycohemoglobin is labeled with a soluble polyanionic affinity reagent and the anionic complex is then captured with a cationic solid-phase matrix. Glycohemoglobin is quantified by measuring the quenching by heme of the static fluorescence from an added fluorophore. The assay is standardized to report both percent total glycohemoglobin (%GHb) and percent hemoglobin A1c (%HbA1c). Glucose, bilirubin, triglycerides, labile fraction, and hemoglobin variants do not interfere in the assay. Within- and between-run CVs are approximately 4-5%, with total CVs of approximately 6.5%. Highly significant linear correlations (r &gt; 0.97) were obtained in comparison studies with two major assay methodologies. The time to obtain one result is approximately 10 min (including assay of a control), 56 min for 22 results. We describe the development, standardization, and validation of this new method.