bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accuracy and precision of breath alcohol measurements for subjects in the absorptive state.
Authors: Simpson G 
Published: January 2020

Abstract
Published data are analyzed in order to estimate the accuracy of breath-alcohol measurements for subjects during absorption of orally ingested ethanol. Simultaneous measurements of breath alcohol concentration (BrAC) and venous blood alcohol concentration (VBAC) show that actual VBAC can be overestimated by more than 100% for a significant amount of time after drinking stops. The maximum error found for four individual subjects is +230%, +190%, +60%, and +30%. The magnitude of these errors indicates that results from quantitative evidential breath alcohol analyzers are far less accurate for the absorptive state than they are during the postabsorptive state, but the specifications for accuracy and precision given by manufacturers of these instruments do not reflect this. The results also indicate that there is a significant likelihood that subjects will be in the absorptive state when tested under field conditions. I conclude that estimates of BAC based on BrAC measurements are not reliable in the absorptive state and that the uncertainty associated with such estimates should be accounted for, particularly when the results are used in connection with law enforcement.
Fluorometric determination of indocyanine green in plasma.
Authors: Hollins B , Noe B , Henderson J M 
Published: January 2020

Abstract
With this fluorometric method for measuring indocyanine green (ICG) in biological fluids, the limit of detection is an order of magnitude lower than for the traditional spectrophotometric procedure. The excitation and emission maxima are 780 and 810 nm, respectively. Agreement was excellent (r = 0.998) between direct results by this method and those by a liquid-chromatographic procedure with spectrophotometric detection. ICG breaks down in aqueous solution; the degradation products can be detected with liquid-chromatographic/spectrophotometric methods, but because the metabolites are not fluorescent, they do not interfere in the method present here. The increased specificity and sensitivity of this method should permit much more complete analysis of the kinetics of ICG disposition.
Assessment of urinary retinol-binding protein as an index of proximal tubular injury.
Authors: Bernard A M , Vyskocil A A , Mahieu P , Lauwerys R R 
Published: January 2020

Abstract
The urinary excretion of retinol-binding protein (RBP), beta 2-microglobulin (beta 2-m), and beta-N-acetyl-D-glucosaminidase was monitored in patients with renal tubular damage secondary to multiple injuries, rhabdomyolysis, antibiotic treatment, or poisoning by various chemicals such as solvents, heavy metals, or pesticides. In almost all cases, RBP proved to be a more sensitive index of renal tubular damage than was beta-N-acetyl-D-glucosaminidase and, being more stable in acid urine, a more practical analyte to measure than was beta 2-m. We corroborated this finding by studying the relationships between these three analytes in more than 150 patients. On the average, an increase in the urinary excretion of beta-N-acetyl-D-glucosaminidase becomes detectable when urinary RBP already exceeds the normal value by 50- to 100-fold. In urines with pH greater than 6, RBP and beta 2-m concentrations are well correlated (r = 0.93, n = 150), beta 2-m tending to be more frequently positive (i.e., greater than 311 micrograms/L). But in urines with pH less than 6 (about 30-40% of the samples), the RBP/beta 2-m concentration ratio increases as pH decreases, up to 500 in some patients with massive tubular injury. Because the renal uptake of proteins involves a saturable process, the urinary excretion of RBP, like that of beta 2-m, specifically reflects the reabsorption capacity of proximal tubules only when the glomerular filtration rate is normal or slightly impaired (i.e., serum creatinine less than 20 mg/L). Under these conditions the determination of RBP protein in urine appears the most appropriate test when early detection of tubular injury is desirable.
Interlaboratory proficiency-testing programs: a computer model to assess their capability to correctly characterize intralaboratory performance.
Authors: Ehrmeyer S S , Laessig R H 
Published: January 2020

Abstract
We developed a computer model of an interlaboratory survey program to study the ability of proficiency testing (PT) programs to detect intralaboratory errors (total, random, and systematic). It uses a base interlaboratory PT population of 400 laboratories and one test laboratory each with uniquely defined intralaboratory characteristics, i.e., mean, standard deviation (SD), and bias. A gaussian random-number generator uses these parameters to simulate 401 test results analogous to the analysis of one PT sample by each laboratory. The test laboratory's intralaboratory error is expressed as various combinations of bias and coefficient of variation (CV); its simulated survey result is evaluated by a performance criterion derived from the group statistics. To eliminate statistical artifacts, the computer model repeats the complete simulation process 400 times and determines the percentage of the test laboratory's results that fail to meet a specified performance criterion. The computer model can use assigned values or actual intralaboratory data.
Improved method for quantifying vitamin D in proprietary infants' formulas and in breast milk.
Authors: Ballester I , Cortes E , Moya M , Campello M J 
Published: January 2020

Abstract
In this new method for quantifying vitamin D in infants' formulas and breast milk, after repeated lipid extraction, samples are further purified by passage through Sep-Pak cartridges, followed by liquid chromatography, then quantified by competitive protein-binding assay. Analytical recovery is estimated by use of added 3H-labeled vitamin D. For repeated assays of a reconstituted proprietary powdered milk formula in two runs, the intra-assay vitamin D values were 9.0 (SD 1.4) (n = 6) and 8.9 (SD 1.6) micrograms/L (n = 7) (t = 0.07). Assay of a proprietary liquid formula yielded values of 14.9 (SD 0.9) micrograms/L (n = 6). For each, the results agreed with the vitamin D content shown on the label. Vitamin D concentrations in breast milk from two groups of lactating mothers of different social class and nutritional status were 2.3 (SD 1.4) (n = 7) and 2.0 (SD 1.7) micrograms/L (n = 7). Overall recoveries ranged from 65 to 75%. Only 2 mL of milk is required, which facilitates sample collection, and the assay is less time-consuming than other current methods.
Reassessment of creatine kinase BB as a marker for cancer of the prostate, breast, and lung.
Authors: Wong S S , Wu A H , Fritsche H A 
Published: January 2020

Abstract
We used an enzyme-linked immunoabsorbent assay to measure creatine kinase (CK; EC 2.7.3.2) BB in the sera of 58 cancer patients. A pre-incubation step with an anti-CK-M antibody-coated bead removed M chain components, and CK-BB was quantified with use of an anti-CK-B antibody-coated tube. No cross reactivity was observed with mitochondrial CK or CK-MM; CK-MB cross reacted slightly (1.6%). Macro CK type 1 was measured as CK-BB. Average analytical recovery of purified CK-BB added to serum was 97.7%. Although the enzyme activity of CK-BB is labile, our studies show that this protein is antigenically stable for 12 months when stored frozen. The upper limit of normal for CK-BB concentration was 0.3 micrograms/L (95th percentile, n = 25). Of the 20 cases of breast cancer of various stages, none showed any increases of serum CK-BB. Only two of 18 patients with prostatic carcinoma (stage D), and two of 10 patients with oat-cell carcinoma of the lung had increased concentrations of CK-BB in the serum. Ten patients with squamous cell cancer of the lung had normal concentration of the enzyme. Thus the CK-BB isoenzyme is not frequently increased in cancers of the prostate, lung, and breast, and it has little apparent value as a tumor marker for these diseases.
Another physician's office analyzer: the Abbott "Vision" evaluated.
Authors: Hicks J M , Iosefsohn M 
Published: January 2020

Abstract
We evaluated the Abbott Vision system, to assess its suitability for use in the physician's office setting. We compared results from Vision for all the available analytes (alkaline phosphatase, urea nitrogen, cholesterol, creatinine, glucose, uric acid, and triglycerides) with results from the Kodak Ektachem 400 and 700. For all analytes, standard curve linearity, assessed with various dilutions of an analyte-supplemented serum pool, was within the ranges claimed by the manufacturer. Within-run precision (CV) for assays of these analytes ranged from 0.9% to 4.7%, run-to-run precision from 1.1% to 7.3%. Comparisons with other methods were generally very good except for a bias in results for blood urea nitrogen and alkaline phosphatase. Hemolysis (hemoglobin at 2.0 and 3.0 g/L) interferes with results for cholesterol, glucose, triglycerides, and uric acid in serum and whole blood. Bilirubin at 82 mg/L interferes with results for creatinine and triglycerides; at 120 mg/L it interferes with cholesterol, glucose, and uric acid results; and at 170 mg/L it interferes with alkaline phosphatase results. Triglycerides up to 5000 mg/L do not interfere with any of the tests. Calibration of the analyzer was stable for one month. We also compared the performance of a skilled operator with that of an unskilled operator and a physician.
Bromcresol purple dye-binding methods underestimate albumin that is carrying covalently bound bilirubin.
Authors: Bush V , Reed R G 
Published: January 2020

Abstract
We used automated and manual versions of two commonly used dye-binding methods for albumin to quantify albumin that had been modified by covalent addition of bilirubin. Dye-binding methods based on reaction with bromcresol purple underestimated the modified albumin by as much as 29%. Dye-binding methods based on reaction with bromcresol green were unaffected by the presence of covalently attached bilirubin. Neither method was affected by the presence of noncovalently bound bilirubin.
Automated analysis for taurine in biological fluids and tissues.
Authors: Goodman H O , Shihabi Z K 
Published: January 2020

Abstract
We have developed an automated method of analysis for taurine, based on incorporating an ion-exchange chromatography column into the continuous-flow AutoAnalyzer (Technicon). After removal of proteins and peptides by dialysis, taurine is selectively eluted from an ion-exchange column and reacted with o-phthaldialdehyde to yield a fluorescent compound. The advantages of this method are: full automation with no need for sample deproteinization or cleanup; sensitivity, detecting as little as 5 mumol/L; speed (20 samples per hour); and flexibility. It can be used for assaying taurine in urine, plasma, cerebrospinal fluid, and tissue homogenates. This method can be adapted for assays of other metabolites.
Biological variation in analyte concentrations in urine of apparently healthy men and women.
Authors: Gowans E M , Fraser C G 
Published: January 2020

Abstract
Analytical, intra-individual, and interindividual components of variation for sodium, potassium, urea, creatinine, calcium, and phosphate were estimated from results for 24-h urine specimens collected from 15 apparently healthy individuals every four weeks for 40 weeks. Expressed as output, mean values differed for men and women, except for calcium. Our data on intra-individual variation were similar to those obtained for 10 men by Shephard et al. (Clin Chem 1981;27:569-73). Calculated analytical goals are easily attained by current methods. Reference values for urine creatinine are useful only when expressed as output and stratified according to gender. The ratios of intra- to interindividual variation generally increase on such stratification; separate reference values for men and women are therefore required for analytes expressed as output. Measurements of sodium and potassium in urine should be reported as concentration, but output terms are favored for the other analytes. Differences for two serial results from an individual must be rather large to differ statistically.
Storage conditions and stability of thyrotropin and thyroid hormones on filter paper.
Authors: Waite K V , Maberly G F , Eastman C J 
Published: January 2020

Abstract
We evaluated the effects of temperature and humidity on thyroid hormones (T4, T3) and thyrotropin (TSH) measured in blood spots dried on filter paper. RIAs for T4 and T3 blood spots were optimized to measure these analytes over the neonatal and euthyroid adult reference intervals. Sensitivities of the T3 and T4 assays were 0.5 and 10 nmol/L, respectively. A blood-spot immunoradiometric assay for TSH involving magnetizable particles was developed with a sensitivity of 6 milli-int. units/L. Control sera stored at -20 degrees C, 4 degrees C, room temperature, 37 degrees C, and at external ambient temperatures for 36 days showed no significant change in measured concentrations of TSH or T3 during 30 days or for T4 at -20 and 4 degrees C. T4 markedly declined in blood spots stored at room temperature (either high or low humidity), 37 degrees C, or ambient temperature. TSH and T3 in blood spots evidently are stable at temperatures likely to be encountered during storage or transport, but blood spots for T4 assay must be stored between -20 and 4 degrees C.
Two-carbon oxalogenesis compared in recurrent calcium oxalate stone formers and normal subjects.
Authors: McWhinney B C , Nagel S L , Cowley D M , Brown J M , Chalmers A H 
Published: January 2020

Abstract
We used a xylitol load to test the two-carbon pathway to oxalate production in humans. Use of this pentose sugar caused a fourfold increase in glycolate excretion, indicating its suitability as a dynamic function test of two-carbon metabolism. However, despite this increase in glycolate excretion in 10 recurrent stone formers and six normal subjects, there was no concomitant increase in oxalate excretion in either group. By comparison, a sucrose load produced no increase in excretion of either glycolate or oxalate. In addition, when we studied four recurrent calcium stone formers on successive diets with various fat content, we found no correlation between high fat intake and increased glycolate or oxalate excretion. In summary, there was no evidence of abnormal fluxes through the two-carbon pathway to oxalate in recurrent stone formers, nor of hyperoxaluria as related to increased intake of sucrose or fat.
Time-resolved immunofluorometric assay of 34-kDa somatomedin-binding protein.
Authors: Koistinen R , Stenman U H , Alfthan H , Seppälä M 
Published: January 2020

Abstract
In this time-resolved immunofluorometric assay for the 34-kDa somatomedin-binding protein (SmBP), affinity-purified polyclonal antibodies are used, along with solid-phase separation of bound and free analyte. The first antibody is bound to polystyrene microtiter wells; the second is labeled with europium(III) chelate. The detection limit of the method is 0.25 microgram/L, much lower than that (about 8 micrograms/L) for radioimmunoassay. By immunofluorometric assay, SmBP is detectable, and could be accurately quantified, in the serum of all 88 individuals we tested, whereas by radioimmunoassay a third of the samples had concentrations below the detection limit. When SmBP was detectable by both methods, the concentrations measured by the two techniques correlated well (r = 0.98).
Using the coefficient of correlation in method-comparison studies.
Authors: Bookbinder M J , Panosian K J 
Published: January 2020

Abstract
The coefficient of correlation (R) is one of the most commonly computed statistics in method-comparison studies. Usually, it is simply quoted without interpretation. In this paper, we show how R may be used to detect interference, nonlinearity, and misuse of the imprecision components. Specifically, one may precisely predict what R should be by considering the imprecisions of the two methods being compared, even before the comparison is performed. When the actual R disagrees with the predicted R, then one of the mentioned effects is present. We also describe a statistical test to detect these effects at the P = 0.05 level, then evaluate this test by using computer simulation and present two examples of its use. We also present the theory underlying the usage of R, including how R is affected by the distribution and range of the data, by the joint imprecisions of the methods being compared, by the sample size, and by the randomness of the specimen-selection process.
Decrease of free thyroxin in serum of lactating women.
Authors: Iwatani Y , Amino N , Tanizawa O , Mori H , Kawashima M , Yabu Y , Miyai K 
Published: January 2020

Abstract
We measured thyroid hormones and thyroxin-binding proteins in serum from 62 normal lactating and 52 nonlactating women at three months postpartum, and compared these values with those for 42 nonpregnant control women of similar age. Mean thyroxin concentrations in the lactating and nonlactating women were significantly (P less than 0.001) lower than that of the nonpregnant controls, but there was no significant difference (P greater than 0.2) in triiodothyronine concentration among these three groups. Free T4 concentration was significantly (P less than 0.01) lower in lactating women than in controls. The reverse-T3 concentrations in both lactating and nonlactating women were significantly (P less than 0.001) lower than in controls, and were significantly (P less than 0.001) lower in lactating than in nonlactating women. The concentration of thyroxin-binding globulin was significantly higher in lactating women than in controls, and the albumin concentration was significantly lower in women postpartum than in controls. Evidently, regulation of thyroid hormone in women postpartum, especially during lactation, differs from that in nonpregnant women.
Differential assay of salivary and pancreatic alpha-amylase in serum and urine, with use of monoclonal antibody to human salivary amylase immobilized on bacterial cell wall.
Authors: Hiroishi S , Matsuyama S , Kurooka S , Sunahara N , Inoue S , Ida T 
Published: January 2020

Abstract
We previously reported (Clin Chim Acta 1986;159:89) that bacterial cell wall chemically coated with a monoclonal antibody specific to human salivary (S) amylase (EC 3.2.1.1) could be successfully used to separate S and pancreatic (P) amylase in solution. We have now applied this method to serum and urine samples and found that the activities of S and P amylases so measured correlated well with those measured by the isoamylase inhibitor method. The present method is simple and reliable for routine clinical tests.
A linear method for determining specific activity of tracers in radioimmunoassays.
Authors: Chiang C S 
Published: January 2020

Abstract
I describe a rapid and objective method for graphically determining specific activity of radioactive tracers by self-displacement. Two sets of results are plotted on the same graph: total/bound counts vs concentration of unlabeled analyte (for the standard curve results) or quantity of radioactivity (for tracer self-displacement results). Because these plots are linear, not only are the difficulties of curve fitting and the need for numerous data points avoided, but also how well the data fit the lines can be assessed by calculating the standard deviation of the slope of the lines. This method minimizes uncertainty between data points, allows easier interpolation, and often yields more precise results than do previously published procedures.
Measurement of direct bilirubin by use of bilirubin oxidase.
Authors: Doumas B T , Perry B , Jendrzejczak B , Davis L 
Published: January 2020

Abstract
We developed an enzymatic method for measuring direct-reacting bilirubin (DBIL) in serum. At pH 4.5, bilirubin oxidase (BOX) oxidizes mono-conjugated bilirubin, di-conjugated bilirubin, and most of the delta-bilirubin to biliverdin. The resulting decrease in absorbance at 460 nm is linearly related to the concentration of DBIL in serum. Mean DBIL values in the 51 patients' sera examined by the BOX method and a diazo procedure (Clin Chem 1982;28:2305) were 45.4 and 42.8 mg/L, respectively. For the same samples, mean values for DBIL and conjugated bilirubin by the Kodak "Ektachem" methods were 50.2 and 24.8 mg/L, respectively. Hemoglobin, up to 1.5 g/L, does not interfere. Unconjugated bilirubin reacts negligibly. Day-to-day CVs were 2.2% and 2.4% at DBIL concentrations of 37 and 74 mg/L, respectively.
Total testosterone, free-androgen index, calculated free testosterone, and free testosterone by analog RIA compared in hirsute women and in otherwise-normal women with altered binding of sex-hormone-binding globulin.
Authors: Wilke T J , Utley D J 
Published: January 2020

Abstract
We compared the clinical value of information on free testosterone as measured with the Coat-A-Count (Diagnostic Products Corp.) radioimmunoassay kit involving a ligand analog with that of total testosterone, the free-androgen index, and free testosterone calculated from concentrations of testosterone, sex-hormone-binding globulin, and albumin, in hirsute women, pregnant women, oral-contraceptive users, women with thyroid disease, and epileptic women taking phenytoin. Total testosterone, the free-androgen index, calculated free testosterone, and free testosterone by RIA were increased in 41-68% of hirsute women. Values for free testosterone increased in the first and third trimesters of pregnancy but remained within normal limits in all non-hirsute groups. Total testosterone was increased in patients having increased sex-hormone-binding globulin, whereas the free-androgen index and, to a lesser extent, calculated free testosterone were significantly decreased. Free testosterone measured by analog RIA not only has greater diagnostic efficiency than total testosterone, it also is technically simpler to determine than the free-androgen index and calculated free testosterone.
Lactate dehydrogenase isoenzymes in serum during recent acute myocardial infarction.
Authors: Rotenberg Z , Weinberger I , Sagie A , Fuchs J , Sperling O , Agmon J 
Published: January 2020

Abstract
Lactate dehydrogenase (LD, EC 1.1.1.27) isoenzymes 1 and 2 and the LD 1:2 ratio were determined in 62 patients with recent myocardial infarction 24, 48, and 72 h after total serum LD activity had returned to normal values. From the results we could define two groups of patients. The first, 40 patients in whom proportions of LD-1 and LD-2 isoenzymes in serum and the LD 1:2 ratio were all within the normal reference interval, all had an uncomplicated course of recovery from myocardial infarction. In the remaining 22 patients, LD-1 still exceeded LD-2 24 to 72 h after total LD activity returned to normal values; i.e., the ratio was similar to that in patients with myocardial infarction. Seven of these 22 patients (32%) had a complicated course, with re-infarction in all seven. Thus, even in the presence of normal total LD activity, a high LD 1:2 ratio may reflect a consistent focal myocardial necrosis in some patients with recent myocardial infarction and may serve as an early marker for further re-infarction.