bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

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

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

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

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

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

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

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

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 < 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

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

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 < 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 < 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

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 > 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.
Ultrasensitive time-resolved immunofluorometric assay of prostate-specific antigen in serum and preliminary clinical studies
Authors: Yu H , Diamandis E P
Published: January 2020

We developed an ultrasensitive method for measuring prostate-specific antigen (PSA) in serum. The assay includes a capture monoclonal anti-PSA antibody coated to microtiter wells, a biotinylated rabbit polyclonal detection antibody, and alkaline phosphatase (ALP)-labeled streptavidin. The activity of ALP is measured with the substrate diflunisal phosphate; the released diflunisal forms highly fluorescent complexes with Tb(3+)-EDTA that are quantified with microsecond time-resolved fluorometry. The assay is precise and accurate and correlates well with the established Hybritech Tandem-PSA kit. Its distinguishing feature is extreme sensitivity (lowest limit of detection is 0.002 micrograms/L or 2 x 10(6) PSA molecules per assay). This is the most sensitive PSA assay reported thus far; we used it to quantify PSA in patients who had undergone radical prostatectomy. Many patients had < 0.01 micrograms/L PSA in their serum. This method could have important clinical applications in postsurgical early detection of relapse or residual prostate cancer, as recently suggested in the literature (Clin Chem 1992;38:1930-2).
Carbohydrate-deficient transferrin quantified by HPLC to determine heavy consumption of alcohol
Authors: Jeppsson J O , Kristensson H , Fimiani C
Published: January 2020

We developed a new fully automated ion-exchange chromatographic method for quantitating carbohydrate-deficient transferrin (CDT) on a Mono Q column. Quantitation relies on the selective absorbance of the iron-transferrin complex at 460 nm. Transferrin isoforms deficient in sialic acid, with pIs 5.7 and 5.9, can easily be separated and quantitated as a percentage of the total transferrin. This method has been applied to samples from teetotalers, occasional drinkers, patients with recent heavy alcohol consumption, and patients during detoxification. The sensitivity of the method was 55% in patients reporting 40-70 g daily ethanol consumption and nearly 100% in heavily intoxicated patients (70-500 g daily consumption). The half-life of the dominating pI 5.7 isoform in this group was 9.5 (+/- 1) days during detoxification. A CDT value > 0.8% is a highly specific marker for alcohol abuse and is greatly superior to other currently available biological markers.
Apolipoprotein E polymorphism in a healthy Swedish population: variation of allele frequency with age and relation to serum lipid concentrations
Authors: Eggertsen G , Tegelman R , Ericsson S , Angelin B , Berglund L
Published: January 2020

We analyzed blood samples from 407 healthy Swedish individuals, 244 men and 163 women, ages 17 to 86 years, for apolipoprotein (apo) E isoforms and serum triglycerides, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and total cholesterol. Parallel genotyping by means of polymerase chain reaction (PCR)-amplified DNA was performed in 200 subjects. Identical results were obtained by genotyping and phenotyping in 95% of all subjects analyzed. The apo E allelic frequencies were 7.8% for epsilon 2, 71.9% for epsilon 3, and 20.3% for epsilon 4. Compared with other Caucasian populations, the present population had a high relative allelic frequency of epsilon 4. The epsilon 4 frequency decreased with increasing age and was significantly lower in individuals > 60 years of age (14.7%). When controlling for age and sex, there were strong correlations between total serum and LDL cholesterol and the various epsilon alleles. The epsilon 4 and epsilon 3 alleles correlated positively with serum cholesterol and the epsilon 4 allele correlated positively with LDL cholesterol. In contrast, HDL cholesterol and serum triglycerides did not show any correlation to the allele types. Thus, the results demonstrate a considerable age variation of the epsilon allele frequency among healthy Swedes and an influence of apo E alleles on serum and LDL cholesterol concentrations.
Dietary nutrient intakes and slight albuminuria in people at least 40 years old
Authors: Metcalf P A , Baker J R , Scragg R K , Dryson E , Scott A J , Wild C J
Published: January 2020

We studied the relation between diet and slight albuminuria in 5416 people, ages 40 years and over, who participated in a health screening survey of a local workforce. Degree of albuminuria showed log-linear univariate relations with dietary protein, cholesterol, and sodium intakes, and negative log-linear univariate relations with dietary fiber and polyunsaturated to saturated fat (P/S) ratio. After adjusting for age, gender, and ethnicity, the relative risk (95% confidence interval) for slight albuminuria was significantly increased in people reporting dietary cholesterol consumption > 226 mg/day compared with people reporting consumption < or = 226 mg/day [1.32 (1.02, 1.70)], and significantly reduced in people reporting dietary fiber consumption > 26 g/day compared with people reporting consumption < or = 26 g/day [0.74 (0.58, 0.95)]. There was no significant effect of dietary protein, P/S ratio, or salt intake. We conclude that risk of slight albuminuria is increased by consumption of dietary cholesterol and reduced by consumption of dietary fiber.
FK506 (tacrolimus), a novel immunosuppressant in organ transplantation: clinical, biomedical, and analytical aspects
Authors: Wallemacq P E , Reding R
Published: January 2020

The macrolide immunosuppressant FK506 (tacrolimus) is a powerful and selective anti-T-lymphocyte agent that was discovered in 1984. This agent, isolated from the fungus Streptomyces tsukubaensis, has a mechanism of action similar to that of cyclosporine. Experimental data were first published in 1987, and clinical trials were started 2 years later in Pittsburgh. The drug has a potent hepatotrophic effect, which could explain its success in liver transplantation. Particularly encouraging results were obtained in liver allograft recipients, suggesting a lower risk/benefit ratio than with other immunosuppressants. However, recent data show that the drug is not devoid of toxicity (mainly nephrotoxicity), which should the percent the need for careful blood monitoring. Several methods of analysis have been described, some satisfactory, others inadequate for routine monitoring. There is still a lack of specific methods to determine routinely the parent drug concentrations in biological fluids for clinical pharmacokinetics purposes. Despite greater experience in therapeutic drug monitoring, the correlation between FK506 concentrations and efficacy or toxicity is still unclear. More investigations are required to better understand and determine the appropriate use of FK506 in organ transplantation and treating autoimmune diseases.
Artificial neural networks in diagnosis of thyroid function from in vitro laboratory tests
Authors: Sharpe P K , Solberg H E , Rootwelt K , Yearworth M
Published: January 2020

We studied the potential benefit of using artificial neural networks (ANNs) for the diagnosis of thyroid function. We examined two types of ANN architecture and assessed their robustness in the face of diagnostic noise. The thyroid function data we used had previously been studied by multivariate statistical methods and a variety of pattern-recognition techniques. The total data set comprised 392 cases that had been classified according to both thyroid function and 19 clinical categories. All cases had a complete set of results of six laboratory tests (total thyroxine, free thyroxine, triiodothyronine, triiodothyronine uptake test, thyrotropin, and thyroxine-binding globulin). This data set was divided into subsets used for training the networks and for testing their performance; the test subsets contained various proportions of cases with diagnostic noise to mimic real-life diagnostic situations. The networks studied were a multilayer perceptron trained by back-propagation, and a learning vector quantization network. The training data subsets were selected according to two strategies: either training data based on cases with extreme values for the laboratory tests with randomly selected nonextreme cases added, or training cases from very pure functional groups. Both network architectures were efficient irrespective of the type of training data. The correct allocation of cases in test data subsets was 96.4-99.7% when extreme values were used for training and 92.7-98.8% when only pure cases were used.
Synthetic peptide-based immunoassay for amino-terminal propeptide of type I procollagen: application for evaluation of bone formation
Authors: Linkhart S G , Linkhart T A , Taylor A K , Wergedal J E , Bettica P , Baylink D J
Published: January 2020

Serum biochemical markers are powerful tools for the evaluation of bone turnover. In this study, we developed a radioimmunoassay, using a synthetic peptide for the N-terminal fragment of human type I [alpha 1(I)] procollagen (N-PCP). A 14-amino acid peptide was synthesized from the amino terminus and used to generate antibodies in rabbits. The synthetic peptide was used as standard and tracer in the assay. Both native type I amino procollagen (PINP), which was purified from skin fibroblasts, and human serum displaced tracer binding in parallel with the synthetic peptide. The range for measurement of N-PCP in serum was 0.7 to 30 micrograms/L (0.21-9.18 nmol/L). In a sample of 17 normal adults and 13 children (ages 9-16 years) there was a strong correlation between serum N-PCP determined by this assay and both skeletal alkaline phosphatase isoenzyme and osteocalcin, markers of bone formation. Serum concentrations of N-PCP in a group of normal children were eightfold higher than concentrations in normal adults, with no overlap between the two groups. N-PCP also correlated with C-terminal type I procollagen determined with a commercially available kit (r = 0.92).
Beta-N-terminal glycohemoglobins in subjects with common hemoglobinopathies: relation with fructosamine and mean erythrocyte age
Authors: Martina W V , Martijn E G , van der Molen M , Schermer J G , Muskiet F A
Published: January 2020

Amounts of beta-N-terminal glycohemoglobins (HbX1c), serum fructosamine, and erythrocyte polyamines were determined in nondiabetic adults with HbAA, HbAC, HbAS, HbCC, HbSC, HbSS, and HbS/hereditary persistent HbF (HPFH). The groups did not differ in fructosamine concentrations. Mean (95% confidence limits) HbX1c percentages were: 4.4 (4.1-4.8) for HbA1c in HbAA, 4.3 (3.9-4.8) for HbA1c in HbAC, 4.1 (3.6-4.6) for HbC1c in HbAC, 4.4 (4.0-4.7) for HbA1c in HbAS, 2.6 (range: 2.3-3.8) for HbC1c in HbCC, 2.0 (1.5-2.4) for HbS1c in HbSC, 0.9 (0.6-1.3) for HbS1c in HbSS, and 1.3 (range: 0.8-2.4) for HbS1c in HbS/HPFH. There was a nonlinear inverse relation between HbX1c and erythrocyte polyamines, indicating that HbX1c percentage decreases with decreasing mean erythrocyte age. We conclude that amounts of HbX1c in subjects with heterozygous hemoglobinopathies should be expressed as a percentage of HbX0 + HbX1c, not total hemoglobin. Interpretation of HbX1c in subjects with a decreased erythrocyte half-life is difficult; measurement of fructosamine seems a suitable alternative.
Fast lipoprotein chromatography: new method of analysis for plasma lipoproteins
Authors: März W , Siekmeier R , Scharnagl H , Seiffert U B , Gross W
Published: January 2020

Fast lipoprotein chromatography (FLPC) is a novel method for quantifying lipoproteins. Plasma proteins are separated by fast-flow gel filtration. Lipoproteins are detected by post-column derivatization with an enzymatic cholesterol reagent. FLPC resolves very-low-, low-, and high-density lipoproteins (VLDL, LDL, and HDL, respectively) and completely separates apolipoprotein Al- and apolipoprotein B-containing lipoproteins. CVs for VLDL-cholesterol, LDL-cholesterol, and HDL-cholesterol are 5.8%, 2.0%, and 1.9%, respectively. We compared FLPC with a combined ultracentrifugation and precipitation method and obtained correlation of r = 0.979, 0.978, and 0.933 for VLDL-cholesterol, LDL-cholesterol, and HDL-cholesterol, respectively. Triglyceride concentrations up to 9.00 g/L did not interfere with the quantification of lipoproteins by FLPC. We conclude that FLPC is a precise and reliable method for the analysis of plasma lipoproteins that complements conventional techniques.
Electrochemical assay system with single-use electrode strip for measuring lactate in whole blood
Authors: Shimojo N , Naka K , Uenoyama H , Hamamoto K , Yoshioka K , Okuda K
Published: January 2020

We have developed an assay system for measuring lactate in whole blood, consisting of a single-use strip of an enzyme-coated electrode and a small meter. The electrode strip is made of three plastic films: a cover sheet, a spacer, and an insulation layer printed with electrodes that are coated with lactate oxidase (EC 1.1.3.x) and ferricyanide as an electron mediator. The meter measures the magnitude of the anodic current of the reduced mediator by the enzymatic reaction and displays the lactate concentration 60 s after a blood sample (5 microL) is applied. The calibration curve was linear up to 20 mmol/L, and the between-run CVs at three concentrations were 1.7-8.4%. Lactate concentrations determined by this method (y) in blood samples from healthy individuals before and after exercise agreed with the results obtained by the conventional enzymatic method (x): y = 0.97x - 0.3, Sy/x = 0.7. This assay provides a rapid and convenient test for measuring blood lactate concentrations.
Clinical utility and validation of emerging biochemical markers for mammary adenocarcinoma
Authors: Werner M , Faser C , Silverberg M
Published: January 2020

The clinical utilities of the emerging biochemical markers for mammary adenocarcinoma CA 15-3, CA 549, CA M26, CA M29, and MCA (mucin-like carcinoma-associated antigen) were assessed by a formal rating according to six desirable marker characteristics. All five indicators similarly have good specificities but limited sensitivities. As a consequence, these markers mainly meet just two desirable criteria: their frequency and degree of expression reflect tumor burden and prognosis, and they may correlate with therapeutic results. The validation of these assay properties by clinical trials was evaluated by another rating system, designed to assess proband sample selection, restrictions on allowable observations, and choice of statistical descriptors. By these benchmarks, the estimates of the prior probabilities of test outcome (sensitivity and specificity) are reasonably definitive, but conclusive judgments about the posterior probabilities of test outcome ("predictive values") and about values and costs associated with testing are not possible. Three approaches to enhance the limited clinical utility of biochemical breast cancer markers are considered: shifts of the diagnostic decision threshold, marker panels, and sequential testing. However, none of these strategies improves the described performance characteristics.
Serum tumor markers for patient monitoring: a case-oriented approach illustrated with carcinoembryonic antigen
Authors: Fritsche H A
Published: January 2020

The effectiveness of patient monitoring with serum tumor markers is improved when the patient's pretreatment baseline is established, regular serial testing is performed, and a clinically significant change of the marker is determined on the basis of objective criteria. Attention must be directed to (a) ensuring long-term assay precision, (b) timing specimen collection to avoid misinterpretation of paradoxical increases (induced by chemotherapy, surgery, or radiation), (c) noting changes in the production or clearance mechanisms of the marker, and (d) recognizing the variability of site-response in patients who have multiple locations of metastatic disease. Clinical decisions to alter therapy should not be based only on tumor marker measurements. In the absence of other clinical data, a tumor marker abnormality should be confirmed with serial samples collected at a time interval dictated by the half-life of the marker. Serial tumor marker testing can improve cancer patient care, especially when effective salvage therapies are available.
Reimbursement of tumor marker tests
Authors: Logue L J
Published: January 2020

The diffusion of new technology is significantly affected by coverage and reimbursement decisions. A variety of agencies (public and private) make decisions as to which technologies or treatments will be covered and what the levels of reimbursement will be. Recently, these agencies' coverage decisions have tended to be strongly affected by whether a technology is cost raising or cost reducing. Historically, a common effect of medical innovation has been improved quality of health care but with a corresponding increase in cost of delivery. The Medicare program has significant influence on the coverage policies of public and private third-party payers. This influence is especially visible in coverage and reimbursement decisions for cancer-related diagnostic procedures and systems. Coverage for these procedures and systems is not widespread because payers have not been convinced of the clinical usefulness of the assays. The industry must take the responsibility of working through the issues surrounding coverage and reimbursement of cancer-related diagnostic procedures with the payers. The ability to successfully negotiate payment for assays requires knowledge of Medicare coverage policies and a grasp of the reimbursement system.
The FDA's perspective on the evaluation of tumor marker tests
Authors: Aziz K J , Maxim P E
Published: January 2020

Cancer marker tests are often proposed for three intended uses: screening, diagnosis, and monitoring. For each intended use, performance characteristics need to be well defined. The utility of a marker in a given setting depends heavily on two predominant performance characteristics--sensitivity and specificity. These parameters must be established with respect to the intended clinical use of the marker. The value of the marker in a particular situation also depends on the effectiveness of therapy for the malignancy. In reviewing a cancer marker test, the US Food and Drug Administration focuses on both the proposed intended use statement and the clinical utility of the marker. The sponsor is expected to provide specific claims data in support of the safety and effectiveness of the device through well-designed and -executed clinical studies. Several cancer markers are already available. In the future, new markers are anticipated that may greatly expand the range of usefulness in cancer diagnosis screening and monitoring.
Perspectives on the future of cancer markers
Authors: Bast R C
Published: January 2020

More fundamental understanding of cell growth regulation will provide novel approaches for detecting, preventing, and treating different cancers. Activation of protooncogenes or loss of tumor-suppressor genes can have both prognostic and therapeutic importance. In epithelial ovarian cancer, poor prognosis is associated with continued expression or overexpression of tyrosine kinase growth factor receptors p170EGFR, p165fms, and p185erbB-2. Over-expression of erbB-2 (HER-2/neu) by breast and ovarian cancers already permits effective targeting of antibodies and immunotoxins. Ultimately, molecular analysis of individual cancers will guide the application of specific therapies to inhibit activated oncogenes or restore the function of tumor-suppressor genes. Circulating growth factors, oncogene products, and tumor-associated antigens may provide markers for earlier detection of some cancers. In epithelial ovarian cancer, concentrations of CA 125 can be increased 1-5 years before clinical diagnosis, and approximately 50% of patients with stage I disease have had an abnormal CA 125 concentration. Combining CA 125 with two novel markers--OVX1 and M-CSF--has retrospectively detected > 98% of stage I ovarian cancers. Although the specificity of the three markers is insufficient for cost-effective screening, serum tests for them could prompt the performance of transvaginal sonography, substantially decreasing the number of sonograms required. Genetic markers in the germ line of patients at increased risk for certain cancers will almost certainly influence strategies for prevention or detection. In familial breast, and ovarian cancer, a locus on chromosome 17q tracks risk of cancer in a fraction of kindreds. How often germline abnormalities will be detected in patients with apparently sporadic cancer remains to be determined.
Mechanism of fructosamine assay: evidence against role of superoxide as intermediate in nitroblue tetrazolium reduction
Authors: Baker J R , Zyzak D V , Thorpe S R , Baynes J W
Published: January 2020

We studied the chemistry of the fructosamine assay for glycated serum proteins by using the model Amadori compound N alpha-formyl-N epsilon-fructoselysine (fFL), an analog of glycated lysine residues in protein. Free lysine was formed at approximately 70% yield during a standard 20-min incubation of fFL with alkaline nitroblue tetrazolium (NBT) at 37 degrees C. Although superoxide dismutase (SOD; EC 1.15.1.1) and catalase (EC 1.11.1.6) decreased the yield of the product, monoformazan dye (MF+), the yield of MF+ was slightly greater under anaerobic than aerobic conditions, excluding a role for superoxide as an intermediate in the reduction of NBT during the fructosamine assay. SOD added to diabetic patients' sera at physiological concentrations also caused a significant (approximately 50%) inhibition of MF+ formation. This inhibition was reduced by addition of nonionic detergents, which contain organic peroxide inhibitors of SOD, to the fructosamine reagent. Overall, these data indicate that the Amadori compound is the direct reductant of NBT in the fructosamine assay and that superoxide is not an intermediate in the reaction. The inhibitory effects of SOD and catalase are most likely the result of oxygen regeneration in the assay mixture.
Multiple forms of prostate-specific antigen in serum: differences in immunorecognition by monoclonal and polyclonal assays
Authors: Zhou A M , Tewari P C , Bluestein B I , Caldwell G W , Larsen F L
Published: January 2020

Prostate-specific antigen (PSA) in serum is primarily complexed with alpha 1-antichymotrypsin (alpha 1-ACT). However, 12-15% of prostate cancer (PCa) patients present with the predominant form being uncomplexed (free) PSA (Lilja et al., Clin Chem 1991;37:1618-24). We report that commercial immunoassays demonstrate variations in reactivity, especially to the uncomplexed form. We fractionated and analyzed commercial controls, PSA complexes prepared in vitro, and sera from patients with PCa or benign prostatic hyperplasia, using molecular sieve chromatography and Hybritech Tandem-R, Abbott IMx, and Ciba Corning ACS PSA assays. Peak integration of PCa samples demonstrated ACS:Tandem-R ratios of 1-1.3 for PSA/alpha 1-ACT complex. In contrast, ratios of uncomplexed peaks ranged from 2 to 4, suggesting a greater reactivity of the uncomplexed form in the ACS PSA assay. Discrepancies between assays, when PSA was measured in unfractionated sera, correlated directly with the percentage of the uncomplexed form. In controls, fractionation revealed the presence of uncomplexed PSA only, with ratios of ACS:Tandem-R and IMx:Tandem-R of 3:1 and 1.8:1, respectively. Immunoblots of PCa sera detected uncomplexed PSA (approximately 30 kDa) and PSA complexes of approximately 95 kDa (PSA/alpha 1-ACT) and > 200 kDa, indicative of alpha 2-macroglobulin. Maximal recognition of all forms of PSA may be important for early detection of disease progression.
Heterologous double-determinant immunoradiometric assay CA 125 II: reliable second-generation immunoassay for determining CA 125 in serum
Authors: Kenemans P , van Kamp G J , Oehr P , Verstraeten R A
Published: January 2020

The new CA 125 II (Centocor) serum assay utilizing the M11 mouse monoclonal antibody as capture antibody and OC125 as tracer antibody, was investigated for its technical and clinical performance against the original CA 125 assay. The CA 125 II test revealed a quadruple increase in signal-to-noise ratio, good intra- and interassay precision (with CVs < 5% and 7%, respectively), improved dilution linearity, and a minimal detectable dose of 0.38 units/mL. Sera were obtained from healthy females (n = 192), women with benign conditions (n = 208), and patients with various cancers (n = 379). Both assays measured highly similar CA 125 distributions with equal reference ranges and nearly identical positivity (> 35 units/mL) rates, resulting in similar receiver-operating characteristic curves and monitoring graphs. Linear regression analysis of results by the two assays (CA 125 = x, CA 125 II = y) in ovarian cancer patients showed, for CA 125 assay values between 0 and 1000 units/mL, a slope of 1.00 and a y-intercept of 12.6 (n = 254, r = 0.8617, P < 0.0001). The heterologous CA 125 II assay appeared to be more accurate in patients who had human anti-mouse antibodies after immunoscintigraphy. The CA 125 II immunoradiometric assay is sensitive and reliable for measuring serum CA 125, and fully retains the cutoff values of 35 and 65 units/mL that were defined with the original CA 125 immunoradiometric assay.
Prostate-specific antigen: biochemistry, analytical methods, and clinical application
Authors: Armbruster D A
Published: January 2020

Prostate-specific antigen (PSA) is a glycoprotein produced exclusively by prostatic tissue. PSA's absolute tissue specificity makes it valuable as a forensic marker and, more important, as a tumor marker for prostatic cancer. Prostatic cancer is prevalent in the older male population and is a major cause of death in men. Previously, prostatic acid phosphatase (PAP) was used to help diagnose and monitor the efficacy of therapy for prostate cancer. PAP has now been displaced by PSA, which has greater clinical sensitivity even though it has less clinical specificity. PSA is useful for monitoring therapy, particularly surgical prostatectomy, because complete removal of the prostate gland should result in PSA being undetectable. Measurable PSA after radical prostatectomy indicates residual prostatic tissue or metastasis, and increasing PSA concentrations indicate recurrent disease. PSA is also useful for screening selected populations of patients with symptoms indicative of prostate cancer; its use for general screening is debatable because of its less-than-optimal specificity, the cost of unselected screening, and the lack of evidence that early detection of prostate cancer decreases morbidity and mortality. Distinguishing between patients with prostatic cancer and those with benign prostatic hypertrophy is particularly difficult because of the overlap in PSA values in the two groups. Determining the rate of change in PSA per year from serial measurements or calculating the ratio of PSA per volume of the prostate gland may allow these two groups to be more readily differentiated.
Isocratic HPLC assay with electrochemical detection of free gamma-aminobutyric acid in cerebrospinal fluid
Authors: Naini A B , Vontzalidou E , Côté L J
Published: January 2020

A method for measuring gamma-aminobutyric acid (GABA) in human cerebrospinal fluid (CSF) by isocratic HPLC with electrochemical detection is described. The method is based on precolumn derivatization of GABA with o-phthaldialdehyde (OPA) and tert-butylthiol (t-BT), separation of the GABA-OPA complex on a reversed-phase column, and quantitation by means of a Coulochem electrochemical detector. The method is highly sensitive and specific for GABA. In three samples of human CSF containing low, medium, and high amounts of GABA, the coefficients of variation between and within runs were 4.5% and 3.6%, respectively. The concentration of GABA in 10 neurologically intact subjects was 92.5 +/- 9.4 nmol/L of CSF.
Multicenter evaluation of Reflotron direct dry-chemistry assay of high-density lipoprotein cholesterol in venous and fingerstick specimens
Authors: Warnick G R , Boerma G J , Assmann G , Endler A T , Gerique G , Gotto A M , Graziani M S , Lippi U , Patsch W , Riesen W F
Published: January 2020

The Reflotron HDL Cholesterol test (Boehringer Mannheim GmbH) directly separates and analyzes high-density lipoprotein (HDL) cholesterol in plasma collected with EDTA in an integrated dry-reagent system suitable for alternative site testing of lipoproteins. We describe a multicenter evaluation of this test by two US and six European laboratories experienced in lipid analysis. Each laboratory compared the Reflotron with the same conventional wet-chemistry method, Boehringer phosphotungstate-Mg2+ precipitation with enzymatic cholesterol assay. Imprecision was within accepted guidelines, with CVs of < or = 8% for fresh and frozen plasmas (median CV 1.7-3.9%) and for lyophilized sera (median CV 3.8-4.7%), similar to those of the conventional method. Results of linear-regression analysis were as follows: Reflotron HDL Cholesterol = 1.03 conventional - 3.9 mg/L, r = 0.987. The Reflotron results were somewhat low in the two US laboratories, demonstrating the need for general standardization of methods for measuring HDL cholesterol. Results from capillary fingerstick plasma agreed well with those from venous-derived plasma; capillary = 1.04 venous + 4.5 mg/L, r = 0.967. The system is relatively insensitive to interference from hemoglobin (< or = 0.75 g/L), ascorbic acid (< or = 0.3 g/L), bilirubin (< or = 50 mg/L), cholesterol (< or = 3.5 g/L), and triglycerides (< or = 4 g/L). The relative ease of operation and the rapid availability of results (within 90 s for plasma collected in EDTA) make the method appropriate for use by well-trained, but not necessarily technical, operators in the physician's office or other alternative sites.
Discrimination of human T-lymphotropic virus type-I and type-II infections by synthetic peptides representing structural epitopes from the envelope glycoproteins
Authors: Rudolph D L , Lal R B
Published: January 2020

Synthetic peptides representing the immunodominant structural motifs of the envelope region of human T-lymphotropic virus types I (HTLV-I) (Env-1(191-214) and Env-5(242-257)) and II (HTLV-II) (Env-20(85-102 and Env-2(187-209)) were used to develop an enzyme immunoassay that could discriminate between HTLV-I and HTLV-II. Serum specimens from individuals whose infections were confirmed and typed by means of the polymerase chain reaction (PCR) were used to determine the sensitivity and specificity of the new assay. When 73 PCR-confirmed HTLV-I specimens were tested with the HTLV-I peptides, the absorbance values for 71 (97.3%) were at least two times higher than the values obtained with the HTLV-II peptides; these samples thus were classified as HTLV-I. Two specimens reacted with all the peptides and, therefore, could not be typed. Conversely, when 59 PCR-confirmed HTLV-II specimens were tested with the HTLV-II peptides, 55 (93%) produced high absorbance values and were typed as HTLV-II; 4 specimens could not be typed. None of the specimens was incorrectly typed; hence, the specificity of this assay was 100%. When this assay was compared with other HTLV immunoassays, the degrees of sensitivity and specificity were similar. The main advantage of this new assay is that synthetic peptides representing variant sequences can easily be added as new variant HTLV strains are identified.
Programming events in the regulation of cell proliferation and death
Authors: Berges R , Isaacs J T
Published: January 2020

In developing new and more successful therapies for preventing and treating cancer, it is critical to understand what normally regulates cell proliferation and cell death and what are the specific dysfunctions associated with these regulations in individual cancers. Here we review the programmed series of molecular, cellular, and biochemical events required for a cell's entrance and progression through the proliferative vs death processes as a starting point for such approaches to new therapies.
Application of simple chromatographic methods for the diagnosis of defects in pyrimidine degradation
Authors: van Gennip A H , Busch S , Elzinga L , Stroomer A E , van Cruchten A , Scholten E G , Abeling N G
Published: January 2020

Recent findings suggest that inborn errors of pyrimidine catabolism are less rare than generally assumed. We propose a complete set of diagnostic methods for these disorders, suitable for the clinical chemistry laboratory, and present relevant reference data. Applications of thin-layer chromatography, high-performance liquid chromatography, and conventional cation-exchange amino acid analysis lead to detection of various defects in pyrimidine degradation, including the recently described deficiencies of dihydropyrimidine dehydrogenase and dihydropyrimidinase. We also illustrate the potential of the methods to analyze for the catabolites expected to be increased in the urine of patients with ureidopropionase deficiency. Possible pitfalls in the diagnosis and ways to prevent misdiagnosis are demonstrated. The methods offer possibilities for clinical chemistry laboratories to extend their diagnostic capacity to the new area of pyrimidine degradation defects.
Measurement of deoxyribonuclease I activity in human tissues and body fluids by a single radial enzyme-diffusion method
Authors: Nadano D , Yasuda T , Kishi K
Published: January 2020

In the single radial enzyme-diffusion (SRED) method for assay of deoxyribonuclease I, a precisely measured volume of the enzyme solution is dispensed into a circular well in an agarose gel layer in which DNA and ethidium bromide are uniformly distributed. A circular dark zone is formed as the enzyme diffuses from the well radially into the gel and digests substrate DNA. The diameter of the dark circle of hydrolyzed DNA increases in size with time and correlates linearly with the amount of enzyme applied to the well. Thus, the SRED can be used for quantitation of deoxyribonuclease I with a limit of detection of 2 x 10(-6) unit. This corresponds to 1 pg of purified urine deoxyribonuclease I. We measured the deoxyribonuclease I activity of 17 different human tissues and body fluids from healthy donors. Urine samples showed the greatest activity, 6.0 +/- 2.2 kilo-units/g protein (mean +/- SD). Serum deoxyribonuclease I activity was 4.4 +/- 1.8 units/L.