bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differences between young and elderly subjects in seasonal and circadian variations of total plasma proteins and blood volume as reflected by hemoglobin, hematocrit, and erythrocyte counts.
Authors: Touitou Y , Touitou C , Bogdan A , Reinberg A , Auzeby A , Beck H , Guillet P 
Published: January 2020

Abstract
Circadian and seasonal rhythms in total plasma proteins were documented in healthy young men (around 24 years old), and in elderly subjects (both sexes), including senile-dementia patients in their eighties. The concentration of plasma proteins within a given group changed predictably (7-13%), depending on the hour of sampling and the season. Concentrations decreased noticeably around 04:00 h, then peaked around 08:00 h (shortly after waking). The 24-h mean concentrations of total plasma proteins were lower in the elderly groups than in the young men. But the seasonal variations of the 24-h mean values were strikingly larger in the elderly groups (7-8 g/L) than in the young men (2-5 g/L). Moreover, the circadian profiles of plasma proteins differed from the profiles of hematocrit, hemoglobin, and erythrocyte counts. Evidently, circadian variations of blood volume may not be the only element accounting for the variations of plasma protein concentrations. We suggest that the rhythms in plasma protein concentrations be taken into account when reference values are set. Circadian and seasonal variations in plasma proteins may also significantly affect the transport and binding of drugs, especially in the aged.
Activities of superoxide dismutase and glutathione peroxidase in schizophrenic and manic-depressive patients.
Authors: Abdalla D S , Monteiro H P , Oliveira J A , Bechara E J 
Published: January 2020

Abstract
Activities of superoxide dismutase (EC 1.15.1.1) and glutathione peroxidase (EC 1.11.1.9) in erythrocytes were evaluated in 50 schizophrenic and 20 manic-depressive patients, who were or were not being treated with different neuroleptic drugs, and results were compared with those for 58 normal individuals. Neuroleptic-treated and untreated schizophrenic patients showed similar activities of superoxide dismutase, about 60% higher than those found in normal individuals (p less than 0.001). In manic-depressive patients treated with either lithium (n = 8) or lithium plus neuroleptic drugs (n = 12), superoxide dismutase activities were increased by about 40% over those of normal subjects (p less than 0.001). Significantly abnormal activities of glutathione peroxidase were found only in the sub-group of schizophrenic women. These results are interpreted in terms of active oxygen species involvement in the psychiatric manifestations.
Evaluation of the dual-precipitation method for determination of cholesterol in high-density lipoprotein subfractions HDL2 and HDL3 in serum.
Authors: Demacker P N , Hak-Lemmers H L , Hijmans A G , Baadenhuysen H 
Published: January 2020

Abstract
We compared the dual-precipitation method for measurement of cholesterol in high-density lipoprotein subfractions HDL2 and HDL3 (Gidez et al., J Lipid Res 1982;23:1206-33) with density-gradient ultracentrifugation in a swinging-bucket rotor (Demacker et al., Clin Chem 1983;29:656-63). The concentration of dextran sulfate 15,000 (DS) needed for optimal accuracy of the HDL2-chol and HDL3-chol values was established empirically. At a DS concentration of 0.87 g/L, the values for HDL2-chol as well as for HDL3-chol in 88 sera did not differ significantly from those obtained by ultracentrifugation. The precision of the method was satisfactory and was related to the concentration. Nevertheless, the dual-precipitation method lacks specificity inasmuch as it produces no fractions that contain only one HDL subfraction. HDL2 and HDL3 each contained an equivalent amount of cholesterol from the other. At increasing DS concentrations, some radiolabeled HDL3 appeared to have precipitated prior to complete precipitation of HDL2. This lack of specificity can be tolerated in large-scale epidemiological studies for screening, but not in small-scale intervention studies or in assay of clinical samples, where better accuracy is needed and ultracentrifugation is preferred.
Homogeneous apoenzyme reactivation immunoassay for thyroxin-binding globulin in serum.
Authors: Schroeder H R , Johnson P K , Dean C L , Morris D L , Smith D , Refetoff S 
Published: January 2020

Abstract
In this automated apoenzyme reactivation immunoassay system (Ames Optimate) for thyroxin-binding globulin (TBG), the sample and N6-aminohexylflavin adenine dinucleotide-labeled TBG react sequentially with antiserum. Then apoglucose oxidase is added to combine with the free fraction and generate glucose oxidase activity, which is measured colorimetrically. The assay requires 100 microL of sample and covers the clinically significant range for TBG (less than 2.5 to 55 mg/L). The first result is obtained in 16 min; assay of 29 samples and their blanks is completed in less than 1 h. The lower limit of detection is about 2.5 mg/L. Between-assay CVs (n = 9) were less than 9%, within-assay CVs (n = 5) were less than 6%, and analytical recovery of TBG was 103-112%. Reagents are stable at 4 degrees C for at least five months. Results by this method for serum TBG (y) compared well with those determined by radioimmunoassay (x): y = 1.029x--0.352 (r = 0.990, n = 49, Syx = 1.165 mg/L). In addition, with 39 other sera the ratio of total thyroxin (by RIA) to TBG compared well with free thyroxin measured by equilibrium dialysis (r = 0.930) and the free thyroxin index (r = 0.970).
Urinary serotonin in the diagnosis of carcinoid tumors.
Authors: Feldman J M 
Published: January 2020

Abstract
To determine whether measurement of serotonin in urine would give useful complementary information to the usual measurement of 5-hydroxyindoleacetic acid (5-HIAA) in urine and platelet serotonin in platelets, I measured these analytes in 75 consecutive patients with carcinoid tumors, and found that 75% had above-normal urinary 5-HIAA excretion, 64% had above-normal serotonin excretion, and 64% had above-normal platelet serotonin concentration. Six patients had increased urinary serotonin, but 5-HIAA excretion and platelet serotonin concentration were normal. Only two of a further 50 patients with solid noncarcinoid tumors--and none of 55 patients with flushing or diarrhea, who did not prove to have a carcinoid tumor--had increased urinary serotonin. Ingestion of four bananas (a food rich in serotonin) increased urinary 5-HIAA but not urinary serotonin excretion of seven normal subjects. Evidently, measurement of urinary serotonin excretion is helpful in the evaluation of patients with suspected carcinoid tumors.
Methotrexate interferes with determinations of conjugated bilirubin with the Kodak Ektachem 400.
Authors: Swanson S , Mifflin T E , Boyd J C 
Published: January 2020

Abstract
Immediately after intravenous infusion of a high dose (concentration in serum greater than 1000 mumol/L) of methotrexate, the apparent conjugated bilirubin (Bc) concentrations in serum of two osteosarcoma patients, as measured by the Kodak Ektachem 400 analyzer, were greater than the corresponding total bilirubin concentrations, but decreased as the concentrations of methotrexate in serum decreased. In an interference study we found that methotrexate added to sera containing a wide range of basal Bc concentrations increased the measured Bc concentration in a linear and dose-related fashion. Methotrexate also interfered negatively with measurements of unconjugated bilirubin (Bu). The source of the interference appears to be an overlap in the absorption spectrum of methotrexate with Bc and Bu at 400 nm.
Increased excretion of histidyl-L-proline diketopiperazine by infants receiving Pregestimil and Nutramigen formulas.
Authors: Roesel R A , Blankenship P R , Mobley E B , Coryell M E 
Published: January 2020

Abstract
Histidyl-L-proline diketopiperazine is excreted in increased amounts by infants receiving Nutramigen or Pregestimil. When these formulas are discontinued, its excretion becomes undetectable. The compound was isolated from Nutramigen and Pregestimil, as well as from the urine of the infants receiving these formulas, and was identified by comparison with authentic histidyl-L-proline diketopiperazine standard in various chromatographic and electrophoretic systems. A neuropeptide widely distributed in the brain and gut and having a variety of biological functions, histidyl-L-proline diketopiperazine may have as-yet-undetermined effects on infants who are receiving these formulas.
Use of Proton Nuclear Magnetic Resonance Spectroscopy in Detection and Study of Organic Acidurias
Authors: lles R A , Hind A J , Chalmers R A 
Published: January 2020

Abstract
Vol. 31, p 1797, column 2: The first paragraph under the heading Methylmalonic Aciduria should read: The spectrum (Figure 4) shows two large methylmalonate resonances ascribable to the CH3 group split by the adjacent CH into a doublet and the CH proton split in turn by the same CH3 group to give a quartet. All five patients with methylmalonic aciduria so far investigated show as the major signal the characteristic presence of large amounts of methylmalonate in their urine regardless of their clinical status, with some 3-hydroxypropionate also being present. Signals due to ketoaciduria were also evident in some samples.
p 2014: In line seven of column one, the interval should read 16-53 µmol/L.
Vol. 32, p 35: In the last two lines of last full paragraph, "70 °C" should read "-70 °C" and "20 °C" should read "-20 °C."
p 175: In Table 1, "0.20-0.96" should read "0.2-3.96."
p 179: In Figure 2, transpose A with C and B with D.
p 223: The Figure to the right should have accompanied the Letter by Brugués and Sastre.
p 521: Ref. 15 in the paper by Helenius and Tikanoja was omitted: Matsubara G, Kudo K, Kawashita T, Takamura K. Spectrophotometric determination of hydrogen peroxide with titanium 2-(5-bromopyridyl)azo-5-(N-propyl-N-sulfopropylamino)phenol reagent and its application to the determination of serum glucose using glucose oxidase. Anal Chem 1985;57:1107-9.
p 536: The second author is Lothar Siekmann.
See image in the PDF file.
Minimizing interlaboratory variation in routine assays of serum cholesterol through the use of serum calibrators.
Authors: Boerma G J , Jansen A P , Jansen R T , Leijnse B , van Strik R 
Published: January 2020

Abstract
A cholesterol standardization program was developed in The Netherlands for clinical laboratories that use their analytical results as indicators of cardiovascular risk. Participants with sufficient precision but inaccurate results are encouraged to use serum-based calibrators as a means to decrease bias. A regional pilot survey and thereafter a national one were carried out in 31 and 138 laboratories, respectively, to investigate whether use of the serum-calibration procedure could improve routinely performed cholesterol measurements. To participants in our national quality-control surveys were mailed three calibrators (pooled human serum) and five human-serum controls, for analysis of cholesterol on four different days. Reference method values had been assigned to the calibrators by the Netherlands Reference Laboratory, applying the U.S. Centers for Disease Control modification of the Abell-Kendall procedure. Using the calibration curves based on results for the serum calibrators decreased the between-laboratory variation (SD) by at least 50%, with improved accuracy for non-enzymatic methods. The initial within-laboratory precision was generally good, and improvements in it were small. To our knowledge, standardization results involving so many routine hospital laboratory procedures have not been previously reported.
Results of routine determination of clinically significant hemoglobin derivatives by multicomponent analysis.
Authors: Zwart A , van Kampen E J , Zijlstra W G 
Published: January 2020

Abstract
Our recently developed multiwavelength method for multi-component analysis of hemoglobin (Hb) derivatives (Clin Chem 1984;30:373-379) was adapted for routine use in the clinical chemical laboratory. The method was applied in 4066 determinations on blood specimens from patients awaiting major surgery (n = 3863) or visiting the outpatient department for pulmonary disease (n = 203). Mean total hemoglobin concentration was 141 (SD 14) g/L. The proportion of HbCO was slightly to moderately increased (1.5-10.0%) in 36.5% of all patients; in a few cases it was as high as 15%. Mean methemoglobin was 0.4% (SD 0.2%) in the surgical patients, but 1.5% (SD 0.8%) in the patients with pulmonary disease. In some patients of the latter group the proportion of methemoglobin amounted to 5%. Sulfhemoglobin was found less than 0.4% in all specimens. Interference by paraproteins and by increased concentrations of bilirubin and lipids in plasma was easily detected by means of the performance checks provided by the spectrophotometer (an HP 8451 UV/Vis). The method is equally suitable for measuring blood samples containing fetal hemoglobin.
Assays of serum lipase: analytical and clinical considerations.
Authors: Lott J A , Patel S T , Sawhney A K , Kazmierczak S C , Love J E 
Published: January 2020

Abstract
We evaluated three commercially available methods for determining lipase (EC 3.1.1.3) in serum--the Du Pont aca, Boehringer Mannheim Diagnostics (BMD), and Kodak Ektachem (EK) procedures--for their analytical properties and diagnostic efficiencies. Titrimetry was used as the comparative method. The BMD and EK methods showed better agreement with the titrimetric method, owing to the presence of the necessary cofactor, colipase, in their reagents. Colipase also increased the analytical sensitivity of the BMD and EK procedures as compared with the aca method. Determinations of serum lipase, by all methods, had a clinical sensitivity in excess of 80% for acute pancreatitis; the specificity of the lipase test was about 60%, or twice that of serum amylase. Serum lipase determinations with the current, simpler technology are superior to total amylase in the diagnosis of patients with acute pancreatitis. When a colipase-supplemented method is used, a serum lipase value greater than 10-fold the upper reference limit appears to be pathognomonic for acute pancreatitis or inflammation of organs close to the pancreas.
Calculating unknown concentrations from nonlinear standard curves.
Authors: Cverna F , Hamlin C R 
Published: January 2020

Abstract
We describe an algorithm and program for calculating unknown concentration values from nonlinear standard data. The program was developed as an alternative to current data-handling techniques used for therapeutic drug enzyme immunoassay (EMIT) systems. The shape of the standard curve for a given analyte is required to be stable through the lifetime of a reagent lot. The relationship between the net change in milliabsorbance and the natural log of standard concentration is linearized once for each lot of reagents. For each subsequent time the assay is performed, one corrects the individual standard points by using the linearized relationship. Unknown concentrations are then calculated by using quadratic Lagrangian interpolation. The algorithm is faster and simpler than curve-fitting by nonlinear least squares, gives comparable results for unknowns, and rejects fewer assays for poor curve fit.
Nonenzymatic glycation of human platelet membrane proteins in vitro and in vivo.
Authors: Sampietro T , Lenzi S , Cecchetti P , Giampietro O , Cruschelli L , Navalesi R 
Published: January 2020

Abstract
Human platelet membrane proteins (PMP), incubated in vitro in the presence of various concentrations of glucose, undergo nonenzymatic glycation, as evidenced by incorporation of [3-3H]glucose radioactivity into the acid-precipitable fraction. The time course of the reaction is linear for the first hours, and the rate of glycation depends on the glucose concentration in the medium: at a glucose concentration of 80 mmol/L, up to 60 nmol of glucose is bound per milligram of PMP. The ketoaminic nature of the glucose/protein linkages was demonstrated by the finding of 5-hydroxymethylfurfuraldehyde by liquid-chromatographic analysis of acid hydrolysates of PMP. We analyzed PMP from 13 subjects with type I poorly controlled diabetes and from 10 nondiabetics. Nonenzymatic glycation, evaluated as nanomoles of the aldehyde per milligram of protein, was much greater in diabetic patients than in nondiabetics: 1.58 +/- 0.70 vs 0.37 +/- 0.18 (mean +/- SD).
Assessing diagnostic tests once an optimal cutoff point has been selected.
Authors: Linnet K , Brandt E 
Published: January 2020

Abstract
The specificity and sensitivity of a quantitative diagnostic test depends on the chosen cutoff point. The common practice of selecting a cutoff point that maximizes the specificity plus the sensitivity, as judged from the observed test results, is studied here by simulation. Test performance is on average assessed too optimistically by this procedure--a phenomenon of importance when sample sizes are small. For example, the average positive bias is up to 15% of the test performance for sample sizes of 25. Furthermore, binomial calculated standard errors of specificity and sensitivity estimates are incorrect. A Monte Carlo statistical method--the "bootstrap procedure"--is applied to correct for bias and to estimate standard errors, including the standard error of the optimal cutoff point. Independent and paired comparisons of two diagnostic tests are also considered when optimal cutoff points have been selected. For this purpose, binomial statistical tests behave satisfactorily. Examples of power functions are presented.
Sampling and analysis techniques for monitoring serum for trace elements.
Authors: Ericson S P , McHalsky M L , Rabinow B E , Kronholm K G , Arceo C S , Weltzer J A , Ayd S W 
Published: January 2020

Abstract
We describe techniques for controlling contamination in the sampling and analysis of human serum for trace metals. The relatively simple procedures do not require clean-room conditions. The atomic absorption and atomic emission methods used have been applied in studying zinc, copper, chromium, manganese, molybdenum, selenium, and aluminum concentrations. Values obtained for a group of 16 normal subjects agree with the most reliable values reported in the literature, obtained by much more elaborate techniques. All of these metals can be measured in 3 to 4 mL of serum. The methods may prove especially useful in monitoring concentrations of essential trace elements in blood of patients being maintained on total parenteral nutrition.
Cyanocobalamin absorption in the elderly: results for healthy subjects and for subjects with low serum cobalamin concentration.
Authors: Nilsson-Ehle H , Jagenburg R , Landahl S , Lindstedt G , Swolin B , Westin J 
Published: January 2020

Abstract
We examined the intestinal absorption of cyano[57Co]cobalamin from a non-protein-bound test dose given to 38 subjects from a population of elderly. The subjects were 76 years old and were apparently free from conditions known to affect cyanocobalamin absorption. Their gastric mucosal function was normal, as judged from determinations of serum gastrin and pepsinogen I. The urinary excretion of radioactivity during the first 24 h was 24(SD 7)%, range 8.6 to 45.2%, corresponding to a health-associated reference interval of 10 to 38%. The results indicate that cyanocobalamin absorption does not decline during normal aging. Duplicate studies were performed in another 20 subjects (70-81 years old) from the same population study; these subjects had a serum cobalamin concentration less than 130 pmol/L. The imprecision (CV) was 23%.
A competitive immunoenzymometric assay for albumin in urine.
Authors: Townsend J C 
Published: January 2020

Abstract
I describe a competitive immunoenzymometric assay for urinary albumin, with use of an immobilized albumin-thyroglobulin conjugate and an affinity-purified antibody. The assay is rapid, easy to perform, has a range of 0.5 to 78 mg/L, and is ideally suited for screening purposes. Higher concentrations may be assayed by further dilution of the urine sample. Results compare favorably with those of a commercially available radioimmunoassay kit.
An optimized method for measuring cyclosporin A with 125I-labeled cyclosporin.
Authors: Felder R A , Mifflin T E , Bastani B 
Published: January 2020

Abstract
We evaluated the use of the new iodinated ligand for the in vitro measurement of cyclosporin A by radioimmunoassay (RIA). Substitution of the iodinated cyclosporin (125I-CyA) for the corresponding tritium-labeled analog (3H-CyA) considerably simplifies and accelerates the currently available RIA, and improves its precision. Analysis of the respective dose-response curves showed that the 50% B0 value was lower for the 125I-CyA assay than for the 3H-CyA assay (37 vs 77 micrograms/L). Use of whole-blood specimens minimized interferences from temperature and hematocrit. We conclude that the use of 125I-CyA in a commercially available RIA for whole-blood specimens is accessible to most laboratories and provides rapid, reproducible data for management of transplant patients.
Uniform chromatographic conditions for quantifying urinary catecholamines, metanephrines, vanillylmandelic acid, 5-hydroxyindoleacetic acid, by liquid chromatography, with electrochemical detection.
Authors: Parker N C , Levtzow C B , Wright P W , Woodard L L , Chapman J F 
Published: January 2020

Abstract
Uniform liquid-chromatographic conditions were developed such that we could quantify norepinephrine, epinephrine, normetanephrine, metanephrine, vanillylmandelic acid, and 5-hydroxyindoleacetic acid in urine by using a single mobile phase of monochloroacetic acid and citric acid, 0.1 mol/L each. All compounds were separated on a C18 column and detected electrochemically at a potential of +0.800 V. Optimization of these uniform chromatographic conditions significantly shortens the changeover time required from one assay to another, resulting in a substantial savings of time and cost to the laboratory.
Emergency screening for ethylene glycol in serum.
Authors: Ryder K W , Glick M R , Jackson S A 
Published: January 2020

Abstract
We have exploited the "interference" of ethylene glycol in the Du Pont aca triglyceride method to develop a convenient and rapid screening method for detecting ethylene glycol in serum. Pretreatment of patient's serum with lipase, glycerol kinase, and other cofactors usually added for triglyceride analysis removes triglycerides and glycerol, but not ethylene glycol, from the sample. The aca triglyceride method may then be used to estimate the ethylene glycol concentration in serum.
Catalytic concentrations of amylase isoenzymes: an assay with wheat-germ inhibitor and 4-nitrophenylmaltopentaoside plus 4-nitrophenylmaltohexaoside as substrate.
Authors: Jiménez A , Arenas J , Santos I , Martínez A 
Published: January 2020

Abstract
We coupled a kinetic procedure to a selective inhibiting method for determining amylase isoenzymes in biological samples, using 4-nitrophenylmaltopentaoside plus 4-nitrophenylmaltohexaoside as substrate and a wheat-germ selective inhibitor with the Gilford S-III spectrophotometer. On plotting remaining amylase activities/total amylase activities (R/T) vs pancreatic amylase activities/salivary amylase activities (P/S) ratios, we found the curve to be linear for P/S ratios from 0.2 to 5. The inhibition rate of amylase inhibitor was constant in solutions having total amylase activities between 20 and (at least) 900 U/L. CVs were 3.1 to 7.1% for pancreatic amylase and 2.0 to 12.9% for salivary amylase in serum. Correlation with the Phadebas method was excellent (r = 0.99) for both pancreatic and salivary amylase. We also automated this procedure in an Hitachi 705 analyzer and correlated the results (r = 0.99) with those by our manual method.