bluuebunny/crossref_metadata_2025 huggingface dataset:
Aromatic L-Amino Acid Decarboxylase Deficiency: Diagnostic Methodology
Authors: Hyland K , Clayton P T
Published: January 2020

Aromatic L-amino acid decarboxylase (EC. 4.1.1.28) deficiency is a newly described inborn error of metabolism that affects serotonin and dopamine biosynthesis. The major biochemical markers for this disease are increases of L-dopa, 3-methoxytyrosine, and 5-hydroxytryptophan in urine, plasma, and cerebrospinal fluid together with decreased cerebrospinal fluid concentrations of homovanillic acid and 5-hydroxyindoleacetic acid. In addition, concentrations of vanillactic acid are increased in the urine. Specific HPLC and gas chromatography-mass spectrometry methods are described that permit the identification and measurement of these metabolites in the above body fluids. Simplified assays for human plasma L-dopa decarboxylase and liver L-dopa and 5-hydroxytryptophan decarboxylase, used to demonstrate the enzyme deficiency, are also reported.
Lactate Measured in Diluted and Undiluted Whole Blood and Plasma: Comparison of Methods and Effect of Hematocrit
Authors: Toffaletti J , Hammes M E , Gray R , Lineberry B , Abrams B
Published: January 2020

We evaluated a new analyzer that measures lactate in undiluted whole blood by direct (or undiluted) amperometry [Nova Stat Profile 7 Analyzer (SP7); Nova Biomedical, Waltham, MA] by comparing it with two other analyzers, one for measuring lactate in whole blood by indirect (or diluted) amperometry [Model 2300; Yellow Springs Instrument Co. (YSI), Yellow Springs, OH] and another for measuring lactate in plasma by enzymatic colorimetry (aca; Du Pont Co., Wilmington, DE). All between-method comparisons of the three methods showed that the results for plasma were comparable (Sy/x = 0.24-0.33 mmol/L). Within-method comparisons by the YSI differed substantially between plasma and whole blood (Sy/x = 0.48 mmol/L), but within-method comparisons by the SP7 produced better agreement between plasma and whole blood (Sy/x = 0.18 mmol/L). The difference between whole blood and plasma by YSI is related to hematocrit, with the greatest differences noted for samples with the highest hematocrit. Serum lactate measured by SP7 had between-day imprecision (CV) ranging from 12% at 0.5 mmol/L to 4.2% at 3.7 mmol/L, showed a linear standard curve to at least 11.5 mmol/L, and was independent of hematocrit. There was a mean bias of approximately 0.4 mmol/L for results in the reference range for both plasma and whole blood by SP7 compared with plasma results by either aca or YSI.
Studies of Lipid Peroxidation Products in Cerebrospinal Fluid and Serum in Multiple Sclerosis and Other Conditions
Authors: Naidoo R , Knapp M L
Published: January 2020

Lipid peroxides were measured in cerebrospinal fluid (CSF) and sera from patients with multiple sclerosis (MS) or other conditions and from control subjects. In serum, visible fluorescence, A240nm, and free and protein-bound thiobarbituric acid (TBA)-reactive substances were significantly greater in MS patients than in control subjects. No such differences were observed in CSF. There was no correlation between lipid peroxides and disease severity or relapse time. We observed a significant positive correlation between CSF protein-bound TBA-reactive substances and CSF protein, suggesting that production of the former depends on protein concentration. A significant negative correlation between free TBA-reactive substances in serum and ultraviolet fluorescence indicated that production of free TBA-reactive substances may be associated with decreased production of fluorescent lipid peroxides. This study provides evidence for increased lipid peroxidation in serum but not CSF from MS patients, suggesting that either there is no increase in CSF lipid peroxidation in MS patients or that CSF lipid peroxides are rapidly removed, possibly by binding to CSF proteins that can be reabsorbed into the blood.
Arsenic Analysis II: Rapid Separation and Quantification of Inorganic Arsenic Plus Metabolites and Arsenobetaine from Urine
Authors: Nixon D E , Moyer T P
Published: January 2020

We describe the rapid separation of inorganic arsenic plus metabolites from arsenobetaine or seafood arsenic in urine. Traditional, high-pressure liquid chromatography is replaced by disposable silica-based cation-exchange cartridges for this separation. Both fractions are quickly separated and collected for analysis by atomic absorption spectrophotometry. Analytical recovery of both fractions is > or = 95%, with an overall precision (CV) ranging from 1.6% to 6.4%. Using this method, we correctly identified the sources of arsenic exposure, whether of inorganic or seafood origin, in 11 urine specimens supplied by the Centre de Toxicologie du Quebec.
Perspectives in Alkaline Phosphatase Research
Authors: Moss D W
Published: January 2020

Gene cloning and site-directed mutagenesis have had a profound effect on alkaline phosphatase research. Four distinct structural genes encoding placental, intestinal, and tissue-nonspecific isoenzymes have been cloned, sequenced, and mapped to human chromosomes. Differences in properties between the respective gene products are due to variations in primary structure involving only one, or a few, key amino acid residues. Recognition that alkaline phosphatase belongs to the category of molecules that are localized to cell membranes through a COOH-terminal glycan-phosphatidylinositol anchor provides a basis for understanding the generation of isoforms observed in plasma in disease. Isoforms produced by differential cleavage or preservation of the glycan-phosphatidylinositol anchor may offer new correlations with disease that are of diagnostic value. However, a more important contribution of alkaline phosphatase research to clinical chemistry may prove to be an increased understanding of disease processes at the molecular level.
Placental Alkaline Phosphatase as the Placental IgG Receptor
Authors: Makiya R , Stigbrand T
Published: January 2020

We review data from our studies of the physiological role of placental alkaline phosphatase (PLAP) and report that, in addition to functioning in catalysis, PLAP has the capacity to bind the Fc portion of human IgG. The dissociation constant for the interaction (3.86 mumol/L) indicates that the PLAP-IgG complex probably occurs in vivo. Furthermore, the electrophoretic and immunochemical properties of PLAP are identical to those of the purified placental Fc receptor. This receptor is believed to participate in the transfer of IgG molecules from the maternal circulation to the fetus during pregnancy. Studies with HEp2 cells show that PLAP is necessary for the internalization of IgG molecules. PLAP behaves, at least in this cell line, as an Fc receptor. The presence of large amounts of PLAP in clathrin-coated vesicles prepared from placenta strongly indicates that PLAP is involved in the endocytic machinery in this organ. We conclude that these results, taken together, suggest a novel biological role for PLAP.
Serum Erythropoietin Concentrations and Iron Status in Patients on Chronic Hemodialysis
Authors: Seguchi Chuichi , Shima Teruo , Misaki Moriharu , Takarada Yoshihiro , Okazaki Toni
Published: January 2020

We studied the relationship between serum erythropoietin (EPO) concentration and iron status in 67 patients undergoing chronic hemodialysis. Serum concentrations of EPO were measured by RIA with recombinant human EPO. The geometric mean of the serum EPO concentration was 10.9 int. units/L (mean +/- SD range = 7.8 - 15.3 int. units/L) in hemodialysis patients, considerably lower than that in normal subjects (12.9 int. units/L). We found no significant correlation between concentrations of serum EPO and hemoglobin in hemodialysis patients, but found a significant negative correlation between serum concentrations of EPO and iron in hemodialysis patients. Moreover, we also found a significant positive correlation between the EPO concentration and the unsaturated iron-binding capacity (UIBC) in serum, and a significant negative correlation between the serum concentrations of EPO and ferritin in hemodialysis patients. Several patients who had relatively high EPO concentrations for hemodialysis patients also had low iron concentrations, high UIBC values, and low ferritin concentrations. These findings suggest that iron was utilized even at these EPO concentrations, which were very low for the degree of anemia observed in the hemodialysis patients.
Discordant Results in Human Chorionic Gonadotropin Assays
Authors: Cole Laurence A , Kardana Andrew
Published: January 2020

Discordance has been reported in human chorionic gonadotropin (hCG) concentrations measured by different immunoassay kits. We examined the results for 40 serum samples assayed with 10 different hCG immunoassay kits. Results varied considerably. Individual sample results varied by as much as 58-fold. Average results for different kits varied by as much as 1.4-fold for pregnancy (20 samples) and 2.2-fold for trophoblast disease (20 samples) serum. We investigated the causes of this discordance. hCG or hCG beta are general names for mixtures of hCG, hCG alpha, or hCG beta immunoreactive molecules in serum. These mixtures include regular hCG, nicked hCG (missing peptide linkages at beta 44-45 or beta 47-48), carbohydrate variants of hCG, hCG missing the beta-subunit C-terminal segment, free beta-subunit, beta-core fragment, and free alpha-subunit. We prepared standards for each of these major variants and measured their reactivities in the 10 hCG immunoassay kits. Free beta-subunit reactivity varied from nonrecognition (anti-beta:anti-alpha type kits; Hybritech Tandem-R and others) to overrecognition (one kit had five-fold greater affinity for free beta than for hCG). Kits with antibodies to beta-subunit C-terminal segment (Organon NML and others) failed to recognize hCG missing this segment, a component of serum hCG in trophoblast disease. Kits with anti-hCG antibodies (Serono MAIA-clone and others) had minimal recognition of nicked hCG (12%), a component of all serum hCG samples, and consistently gave the lowest values with all serum samples. We conclude that differences in recognition of nicked hCG, free beta, and these other hCG variants cause discordance in hCG immunoassay results.
Comparing the Power of Quality-Control Rules to Detect Persistent Systematic Error
Authors: Parvin C A
Published: January 2020

A simulation approach that allows direct estimation of the power of a quality-control rule to detect error that persists until detection is used to compare and evaluate the error detection capabilities of a group of quality-control rules. Two persistent error situations are considered: a constant shift and a linear trend in the quality-control mean. A recently proposed "moving slope" quality-control test for the detection of linear trends is shown to have poor error detection characteristics. A multimean quality-control rule is introduced to illustrate the strategy underlying multirule procedures, which is to increase power without sacrificing response rate. This strategy is shown to provide superior error detection capability when compared with other rules evaluated under both error situations.
Development and In Vitro Characterization of a New Immunoassay of Cardiac Troponin T
Authors: Katus H A , Looser S , Hallermayer K , Remppis A , Scheffold T , Borgya A , Essig U , Geuss U
Published: January 2020

We describe a new one-step enzyme immunoassay of troponin T that uses two specific monoclonal antibodies and streptavidin-coated tubes as the solid phase. The monoclonal antibodies were obtained by conventional hybridoma technology, with human troponin T as antigen. The identity of the cardiac troponin T antigen was confirmed by analysis of the amino acid composition and by partial sequence analysis. The specificity of the monoclonal antibodies for cardiac troponin T was proved by immunoblot analysis and displacement curves. The capture antibody is labeled with biotin. The second antibody is conjugated to horseradish peroxidase (EC 1.11.1.7). The assay [Enzymun-TestR system (Boehringer Mannheim GmbH)] is performed in only 90 min at room temperature; the measuring range for troponin T is 0.1 to 15 micrograms/L. The assay shows excellent between-run precision (CV = 3.3-4.9%).
Laser Immunonephelometry Reference Intervals for Eight Serum Proteins in Healthy Children
Authors: Malvy D J , Povéda J D , Debruyne M , Montagnon B , Burtschy B , Herbert C , Cacès P , Houot O , Amédée-Manesme O
Published: January 2020

Eight serum proteins were analyzed with the Behring nephelometer in samples from 479 healthy French children, ages three to 16 years. Girls had higher concentrations of IgM and albumin than boys had. Age appeared to be a main factor of variation for the proteins tested. Reference intervals are presented for IgG, IgA, IgM, albumin, transthyretin (prealbumin), retinol-binding protein, alpha 1-acid glycoprotein, and C-reactive protein. The significance of increased concentrations of C-reactive protein within a community is discussed.
Circadian Changes in Plasma Phosphate Concentration, Urinary Phosphate Excretion, and Cellular Phosphate Shifts
Authors: Kemp G J , Blumsohn A , Morris B W
Published: January 2020

The concentration of phosphate (Pi) in plasma, Pi excretion, and the tubular threshold of Pi resorption (TmP/GFR) all increase throughout the day from about 1100 to 0300 h. For plasma [Pi], cosinor analysis yielded the following estimates of the parameters of this pattern (with 95% confidence limits): amplitude = 0.17 (0.07-0.26) mmol/L, phase = peak at 0201 (1127-0342) h, and MESOR = 1.14 (1.11-1.18) mmol/L. The increase in TmP/GFR reflects an underlying change in renal Pi handling, which is not attributable to changes in parathyrin concentrations. The changes in Pi excretion work both for and against the changes in plasma [Pi], at different times. The calculated net nonrenal flux of Pi into the extracellular fluid increases in the morning and remains high until 0300 h, and neither it nor Pi excretion nor plasma [Pi] shows any relation to meals. This illustrates the importance of transient net fluxes of Pi between intracellular and extracellular spaces in the control of hour-to-hour changes of plasma [Pi].
D-Mannose as a Preservative of Glucose in Blood Samples
Authors: Chan A Y , Ho C S , Chan T Y , Swaminathan R
Published: January 2020

We studied the changes in blood glucose concentration in blood samples collected in heparinized specimen tubes containing no other preservative, or containing NaF, D-mannose, or a combination of NaF and D-mannose. Blood concentration in samples taken into NaF decreased by 0.40 mmol/L in the first 2 h; thereafter, there was no change. In samples collected into mannose there was a small but significant decrease in blood glucose concentration with time. When samples containing mannose were analyzed immediately after collection, the concentration of glucose was higher than in later analyses, probably because of an exchange of intracellular glucose for extracellular mannose. When a combination of NaF and mannose was used, the blood glucose concentration was relatively stable but slightly higher than nonpreserved samples for the next 24 h. However, samples containing mannose were unsuitable for electrolyte analysis. We conclude that a combination of D-mannose and NaF may be a better preservative for blood glucose than either compound alone.
Free Triiodothyronine in Sera of Acutely Ill General Medical Patients: a Prognostic Indicator
Authors: Mak Y T , Chan E L , Chan A , Woo J , Swaminathan R
Published: January 2020

We measured free triiodothyronine (FT3), thyrotropin (TSH), and C-reactive protein (CRP) in sera of 39 acutely ill medical patients who died within three months of admission and 39 age- and sex-matched control patients selected at random from a total of 294 acute medical admissions. Serum FT3 in nonsurvivors (1.91 +/- 1.51 pmol/L) was significantly lower than that in survivors (3.01 +/- 1.3 pmol/L, P less than 0.01) and the CRP in nonsurvivors (54.6 +/- 59.2 mg/L) was significantly higher than in survivors (43.6 +/- 59.5 mg/L, P less than 0.05). There was no difference in plasma TSH between the two groups. The estimated odds ratio relating death to a plasma FT3 value less than 1.0 pmol/L on admission was 17 (highly significant: P less than 0.001). We conclude that plasma FT3 may be a useful prognostic indicator in acutely ill patients.
Biochemical Diagnosis of Pheochromocytoma by Simultaneous Measurement of Urinary Excretion of Epinephrine and Norepinephrine
Authors: Smythe G A , Edwards G , Graham P , Lazarus L
Published: January 2020

The utility of specific assay of urinary catechols in pheochromocytoma diagnosis was examined by reviewing our data on the investigation of pheochromocytoma in a population of 2476 patients investigated over a six-year period. We used specific gas-chromatographic/mass-spectrometric (GC/MS) analysis for the simultaneous measurement of norepinephrine, dopamine, and the neuronal metabolites 3,4-dihydroxyphenylglycol (DHPG) and 3,4-dihydroxyphenylacetic acid (DOPAC) in all samples; the last two years of data collection (from 1101 patients) also included the specific GC/MS assay of epinephrine. The importance of assaying epinephrine as well as norepinephrine was shown by these latter data. During this latter period, 19 of 1101 patients were found to have pheochromocytoma; of these, nine had tumors that exclusively secreted norepinephrine, six had tumors that exclusively secreted epinephrine, and four exhibited excess production of both norepinephrine and epinephrine. Neither dopamine nor DOPAC was useful in the diagnosis of pheochromocytoma. A substantial proportion of patients may have uniquely epinephrine-secreting pheochromocytomas, previously considered a rarity. Thus we recommend that the biochemical testing for pheochromocytoma include the specific measurement of both norepinephrine and epinephrine.
Improved Diagnosis of Carcinoid Tumors by Measurement of Platelet Serotonin
Authors: Kema I P , de Vries E G , Schellings A M , Postmus P E , Muskiet F A
Published: January 2020

Carcinoid patients are diagnosed biochemically on the basis of increased urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA); urinary and platelet serotonin concentrations are considered to provide complementary information. Using established HPLC methods with fluorometric detection, we evaluated the clinical usefulness of measurements of urinary 5-HIAA and urinary, plasma, and platelet serotonin in 30 consecutive patients with histologically proven carcinoid tumors of fore-, mid-, and hindgut origin before treatment. Ten patients showed no signs of serotonin overproduction; 14 had increased concentrations of urinary 5-HIAA and platelet serotonin; and platelet serotonin, but not urinary 5-HIAA, was increased in 6. None had increased urinary 5-HIAA excretion without an increase in platelet serotonin content. In cases with high rates of tumor serotonin secretion, platelet serotonin reached a maximum and did not correlate with serotonin secretion rate, whereas urinary 5-HIAA was correlated. Increased platelet serotonin was correlated with increased plasma serotonin and with occurrence of carcinoid syndrome. Increased urinary serotonin, allegedly caused by increases in circulating 5-hydroxytryptophan, almost invariably coincided with increased platelet serotonin, but not necessarily with above-normal urinary 5-HIAA excretion. From these results and long-term monitoring of three patients during treatment, we conclude that platelet serotonin is more sensitive than urinary 5-HIAA for detecting carcinoids that secrete only small amounts of serotonin.
Ultrasensitive Thyrotropin Immunoassay Based on Enzymatically Amplified Time-Resolved Fluorescence with a Terbium Chelate
Authors: Papanastasiou-Diamandi A , Christopoulos T K , Diamandis E P
Published: January 2020

We describe an ultrasensitive, enzymatically amplified time-resolved fluorescence immunoassay of thyrotropin (thyroid-stimulating hormone) in serum with use of a terbium chelate as the detectable moiety. In this assay, thyrotropin is first simultaneously reacted with a solid-phase (microtiter well) monoclonal antibody and a soluble biotinylated monoclonal detection antibody. After washing, a streptavidin-alkaline phosphatase conjugate is added, followed by another washing. Alkaline phosphatase acts on the substrate 5-fluorosalicyl phosphate (FSAP) to produce 5-fluorosalicylic acid (FSA). FSA, but not FSAP, can then form with Tb3+ and EDTA a highly fluorescent ternary complex of long fluorescence lifetime. This complex is quantified with time-resolved fluorometry. The thyrotropin assay is highly sensitive (detection limit approximately 0.003 milli-int. unit/L when a total assay time of 85 min is used), precise, and accurate. The thyrotropin assay can also be completed in less than 30 min (detection limit 0.013 milli-int. unit/L), thus making this procedure a candidate technology for high-throughput automated analyzers.
Effect of in Vitro Hemolysis on 25 Common Biochemical Tests
Authors: Yücel D , Dalva K
Published: January 2020

Clinical chemists frequently encounter hemolyzed samples. Our study examines the effects of hemolysis on the results of 25 common biochemical tests. We collected 60 15-mL blood samples from inpatients and outpatients and mechanically hemolyzed 10 mL of the samples in a two-step procedure. We classified serum from these samples as being nonhemolyzed, moderately hemolyzed, or severely hemolyzed and then performed 25 common biochemical tests. Statistical analysis of the results showed that hemolysis had the greatest effect on the lactate dehydrogenase, acid phosphatase, and potassium tests.
Wheat-Germ Lectin Affinity Electrophoresis for Alkaline Phosphatase Isoforms in Children: Age-Dependent Reference Ranges and Changes in Liver and Bone Disease
Authors: Crofton P M
Published: January 2020

This modified lectin affinity electrophoresis method is suitable for simultaneous measurement of liver, bone, and high-molecular-mass (high-Mr) isoforms of alkaline phosphatase (ALP; EC 3.1.3.1) in children. Age-related isoform reference ranges were derived for 247 children, ages 0-13 years. Liver ALP did not appear in plasma until after six months of age, and remained constant after one year of age. Bone ALP was highest in the youngest age group, and declined to relatively constant activities thereafter. High-MrALP was not detected in normal children. In bone disease, the bone isoform was increased in all age groups. In liver disease, only 5 of 30 infants younger than six months had detectable liver ALP, although half had increased bone ALP. Among children older than six months, 5 patients with biliary atresia and 15 patients with hepatitis A all had increased liver isoform activity. Liver ALP was also a sensitive index of early hepatobiliary complications in 27 nonjaundiced children with cystic fibrosis. Measurement of ALP isoforms therefore yields useful clinical information in children older than six months but is of doubtful value in younger infants.
Malondialdehyde Kit Evaluated for Determining Plasma and Lipoprotein Fractions that React with Thiobarbituric Acid
Authors: Richard M J , Portal B , Meo J , Coudray C , Hadjian A , Favier A
Published: January 2020

The determination of thiobarbituric acid reactants (TBARs) is a widely used method for investigating overall lipid peroxidation. An assay kit that could be used with plasma and lipid fractions would facilitate standardization of the method. The results reported here indicate that the malondialdehyde (MDA) kit manufactured by Sobioda (Grenoble, France) complies with criteria of good analytical practices. The detection limit was 0.11 mumol of MDA per liter of plasma. The within-run (CV = 1.8-3.3%) and between-run (CV = 3.3-4.4%) precisions were acceptable. The analytical recovery of MDA after supplementing human plasma samples with tetraethoxypropane standards varied from 88% to 100%. The mean (SD) lipoperoxide concentration determined in 32 healthy adults, ages 20-40 years, was 2.51 (0.25) mumol/L. No significant sex-related difference was noted: 2.57 (0.28) in men vs 2.44 (0.20) mumol/L in women. Applying the method to lipid fractions showed that lipoprotein fractions contain relatively little MDA: 0.07 (0.03) mumol/L of plasma for very-low-density lipoproteins and 0.19 (0.10) mumol/L for low-density lipoproteins.
Direct Time-Resolved Fluorescence Immunoassay of Progesterone in Serum Involving the Biotin-Streptavidin System and the Immobilized-Antibody Approach
Authors: Kakabakos S E , Khosravi M J
Published: January 2020

We developed a direct competitive-type immunoassay for progesterone in serum that combines the advantages of the biotin-streptavidin system with the antibody-immunobilization approach. We synthesized biotinylated progesterone derivatives of five different proteins and, after initial evaluation of the conjugates, selected biotinylated bovine IgG-progesterone as the most suitable tracer. Progesterone released from binding proteins with danazol competes with the biotinylated tracer conjugate for binding to a limited amount of a mouse anti-progesterone monoclonal antibody in microtitration wells coated with a goat anti-mouse IgG antibody. The binding of the biotinylated tracer is then monitored by reaction with a streptavidin-based universal detection reagent developed for time-resolved fluorometry. The assay demonstrated typical performance characteristics with respect to the dynamic range, detection limit, and precision. Recovery averaged 99.3% (SD 8.3%) and dilution experiments showed good linearity. Measurements correlated well with those from three commercially available direct immunoassays for progesterone.
Special Collection and Storage Tubes for Blood Endotoxin and Cytokine Measurements
Authors: Redl H , Bahrami S , Leichtfried G , Schlag G
Published: January 2020

Commercially available blood-collection tubes may be contaminated with endotoxin (315 +/- 95 pg/tube) and could therefore be unsuitable for blood collection for endotoxin measurement. Plasma separation and storage are a potential source of contamination. To avoid contamination and error, we have developed new blood collection tubes that contain heparin free of endotoxin (LPS) and a gel to separate plasma and blood cells. The LPS content is less than 4 pg/tube. Samples can be stored and frozen without plasma withdrawal to preclude contamination. LPS recovery experiments have shown that the new blood-collection tubes do not bind LPS to the separation gel or vial wall. With these tubes, in vitro formation of tumor necrosis factor (404 +/- 163 ng/L in standard tubes vs less than 40 ng/L in special collection tubes) is minimized.
Laboratory Values in Fit Aging Individuals--Sexagenarians through Centenarians
Authors: Tietz N W , Shuey D F , Wekstein D R
Published: January 2020

We determined approximately 15,000 laboratory values in 236 individuals between the ages of 60 and 90 y, 22 individuals between 90 and 99 y, and 69 individuals greater than or equal to 100 y, and compared these with values in young adults. We tested 47 different analytes in the 60-90-y group and 93 analytes in the greater than or equal to 90-y group. Na, K, Cl, and CO2 values were either identical or showed minimal change with age; pH decreased slightly. Differences in Ca values were only minor, but ionized Ca increased slightly. Phosphate decreased in men, but changed only minimally in women; parathyroid hormone increased with age. Increases with age were also observed for glucose, insulin, and C-peptide. Among the enzymes, alkaline phosphatase increased in women, but in men only greater than 90 y; gamma-glutamyltransferase increased in both sexes. Creatine kinase (CK) decreased slightly in individuals greater than 70 y and markedly in those greater than 90 y of age, whereas CK-MB decreased markedly greater than 70 y, reaching the detection limit in individuals greater than 90 y. Lactate dehydrogenase isoenzyme 5 decreased slightly with age. Urea nitrogen increased gradually with age, but creatinine increased only in individuals greater than or equal to 90 y. The increase in urea is not paralleled by a loss of protein in urine, suggesting that the possible cause of azotemia may not always be renal pathology. Urate increased in women but not in men. Liver function, as measured by total bilirubin and liver enzymes, was exceedingly well maintained. Concentrations of most proteins show little change, except for slight decreases in prealbumin, albumin, and transferrin, proteins used as an index of nutritional status. IgA values increased, IgG ranges were wider, IgM and IgD decreased, and the range for IgE was narrower than in young adults. Cholesterol, high-density lipoprotein cholesterol, and triglyceride values increased with age, but decreased in individuals greater than or equal to 90 y. Among the trace elements, magnesium changed little, zinc and lead decreased, and copper values increased with age. Total triiodothyronine and thyroxine decreased, with concomitant increases in thyroid-stimulating hormone. More individuals had increased microsomal antibodies and thyroglobulin titers in the aging population than in the young. In men, the free, percent free, bioactive, and total testosterone values decreased, but luteinizing hormone (LH) and follicle-stimulating hormone (FSH) values increased. In women, estrone and estradiol values decreased, with concomitant increases in LH and FSH. Androstenedione and progesterone decreased in both sexes.(ABSTRACT TRUNCATED AT 400 WORDS)
Age-Related Changes of Neuron-Specific Enolase, S-100 Protein, and Myelin Basic Protein Concentrations in Cerebrospinal Fluid
Authors: van Engelen B G , Lamers K J , Gabreels F J , Wevers R A , van Geel W J , Borm G F
Published: January 2020

Studies on cerebrospinal fluid (CSF) concentrations of neuron-specific enolase (NSE), S-100 protein, and myelin basic protein (MBP) in patients with neurological lesions indicate a quantitative relation between the degree of cell damage in the central nervous system (CNS) and the concentration of these CNS-specific proteins in CSF. Thus NSE, S-100, and MBP could be of use as markers for destructive processes in the CNS. We collected 937 specimens of CSF from children and adults (from newborns to age 91 years) who were undergoing a diagnostic lumbar puncture for several clinical indications. Of these, 79 samples from subjects ranging in age from 0.7 to 66 years could be used retrospectively to construct a reference interval according to our criteria. In these 79 samples no sex dependency existed. The relative increase of NSE, S-100, and MBP with age was similar (1% per year), suggesting a common underlying mechanism. These results emphasize the necessity of using age-matched reference values when the CNS-specific proteins are to be evaluated in neurological diseases. We also present three case histories to discuss the possible clinical relevance of the measurement of NSE, S-100, and MBP in children and adults.
Concentration Dependencies of Immunoturbidimetric Dose-Response Curves: Immunoturbidimetric Titer and Reactivity, and Relevance to Design of Turbidimetric Immunoassays
Authors: Shahangian S , Agee K A , Dickinson R P
Published: January 2020

To characterize polyclonal antisera for two-point immunoturbidimetric applications, we defined, as functions of antiserum concentration, two parameters derived from dose-response curves: the maximum bichromatic optical response, Tmax, and the antigen concentration in the region of excess antibody corresponding to one-half Tmax, or C50. We raised monospecific polyclonal antisera in goats against several human immunoglobulins, C-reactive protein, C3, C4, apolipoproteins A-I and B, and several other proteins. We could linearly relate the logarithm of the antiserum concentration to log C50 and to log Tmax. The concentration of polyethylene glycol affected not only C50 and Tmax but also their functional dependencies on antiserum concentration. We devised two definitions of immunoturbidimetric titer and related them to the titer obtained by the single radial immunodiffusion method of Becker (Immunochemistry 1969; 6:539-46).
Single Stable Reagent (Arsenazo III) for Optically Robust Measurement of Calcium in Serum and Plasma
Authors: Leary N O , Pembroke A , Duggan P F
Published: January 2020

We describe a method based on a single stable reagent for the determination of calcium in serum and plasma with use of Arsenazo III, 200 mumol/L in 50 mmol/L 1,4-piperazinediethanesulfonic acid (PIPES) buffer. The method showed significant positive interference in plasma at pH less than 6.6 because of the precipitation of fibrinogen, which was eliminated by increasing the pH to 6.8. The assay showed no interference from as much as 600 mumol of bilirubin and 12 g of hemoglobin per liter when applied in a simple monochromatic procedure at 660 nm. The standard curve for calcium was linear from 0 to 5.0 mmol/L. Addition of Intralipid at concentrations greater than 3 g/L demonstrated positive interference, which could be eliminated by using a 700-nm blanking wavelength. The procedure showed good agreement with all-method mean values from two external quality-control schemes.
Radioreceptor Assay for Quantifying FK-506 Immunosuppressant in Whole Blood
Authors: Murthy J N , Chen Y , Warty V S , Venkataramanan R , Donnelly J G , Zeevi A , Soldin S J
Published: January 2020

We describe a quantitative radioreceptor assay (RRA) for quantifying FK-506 in whole blood. FK-506 extracted from whole blood with a cyclohexyl-sorbent column competes with [3H]dihydro-FK-506 for binding to a partially purified preparation of FK-506 binding protein (FK-BP). Free and protein-bound FK-506 are separated on LH 20 Sephadex chromatographic columns. We compared the results of this method with those of an enzyme immunoassay that uses a monoclonal antibody: r = 0.97, Sy/x = 0.039. Between-day precisions (CV) at FK-506 concentrations of 8 and 17 micrograms/L were 9.2% and 8.2%, respectively. Within-run precisions were 5.9%, 8.1%, and 9.4%, respectively, at 4, 8, and 15 micrograms/L. Analytical recovery, evaluated at 5, 10, 15, 20, and 25 micrograms/L for FK-506 added to whole blood, ranged from 98% to 103%. The assay can reliably quantify FK-506 blood concentrations between 1.0 and 25 micrograms/L.
Serum Adenosine Deaminase: Isoenzymes and Diagnostic Application
Authors: Ungerer J P , Oosthuizen H M , Bissbort S H , Vermaak W J
Published: January 2020

Human adenosine deaminase (ADA; EC 3.5.4.4) consists of three isoenzymes: ADA1, ADA1+CP, and ADA2. We developed an electrophoretic technique to distinguish between these three isoenzymes. The isoenzyme pattern was studied in tissue and cell homogenates, as well as in serum from normal subjects and from patients with increased serum ADA who had either hepatitis, infectious mononucleosis, tuberculosis, pneumonia, rheumatoid arthritis, or acute lymphoblastic leukemia (ALL). The highest ADA activity was found in lymphocytes and monocytes. ADA2 could be detected only in monocytes (18% of total ADA activity). It was also the predominant isoenzyme in the sera of controls and all disease groups, except for ALL--the only condition evaluated that is not of an inflammatory nature. We conclude that serum ADA reflects monocyte/macrophage activity or turnover in most diseases studied. The exception is ALL, where serum ADA most probably originates from lymphocyte precursors.
Measuring Albumin and Calcium in Serum in a Dual Test with the Hitachi 704
Authors: Leary N O , Pembroke A , Duggan P F
Published: January 2020

We describe a method for simultaneously determining albumin, by using bromcresol purple, and calcium, by using Arsenazo III, in the same analytical cuvette on the Hitachi 704. Both assays agree well with accepted procedures. The standard curves for the albumin and calcium assays are linear from 0 to 60 g/L and 0 to 5.0 mmol/L, respectively. Calibration is stable for 7 days with use of open reagent in the instrument. Both assays are unaffected by hemoglobin less than or equal to 5 g/L and Intralipid less than or equal to 4 g/L; calcium is unaffected by bilirubin less than or equal to 600 mumol/L.
Testing for Creatine Kinase and Creatine Kinase-2 in Ontario: Reference Ranges and Assay Types
Authors: Henderson A R , McQueen M J , Patten R L , Krishnan S , Wood D E , Webb S
Published: January 2020

In 1991, 246 and 136 Ontario laboratories performed total creatine kinase (CK; EC 2.7.3.2) and creatine kinase-2 (CK-2) assays, respectively. A questionnaire mailed to these laboratories requested information about the types of assay used, the origin of their reference ranges, and the source of their instruments and reagents. All laboratories used current test formulations for CK, although seven laboratories did not assay at 37 degrees C. For CK, 69% of all laboratories reported different upper reference limits for men and women (5th-95th percentiles: 160-250 and 115-215 U/L, respectively); 31% reported similar ranges for both sexes. Fifty-six percent derived their own ranges; the remainder used either kit inserts or literature references, and nearly 60% of this latter group claimed to have validated these suggested ranges before use. For 6% of all laboratories, their pediatric ranges were similar to their adult ranges. For CK-2, only 32% used their own reference range; the remainder used kit inserts or literature references, but only 49% of this group validated these ranges before use. Reference limits (5th-95th percentiles) for CK-2 were as follows: activity 6-24 U/L; fraction of CK, 0.022-0.06; and, for mass assays, 5-10 micrograms/L and relative index 0.015-0.04.
Serum and Tissue Carnitine Assay Based on Dialysis
Authors: Shihabi Z K , Oles K S , McCormick C P , Penry J K
Published: January 2020

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

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

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

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

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

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

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

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

Time-resolved fluoroimmunoassay was developed for the detection of synovial-type phospholipase A2 (s-PLA2) in human serum. This solid-phase, sandwich assay uses a polyclonal rabbit antibody raised against synovial-type group II PLA2 produced in Escherichia coli. No cross-reactions were detected between s-PLA2 and PLA2 from human or porcine pancreas, human ascitic fluid, or bee or cobra venom. In healthy individuals, the average concentration of s-PLA2 is 3.7 micrograms/L, with a 95% reference interval from 1.3 to 10.8 micrograms/L. We investigated pancreatic PLA2, which is a group I PLA2, and synovial-type group II PLA2 in sera of patients with hematological malignancies and septic fever. The concentration of s-PLA2 was increased in patient sera and correlated significantly with the catalytic activity of PLA2 and the concentration of C-reactive protein. No correlation with the concentration of pancreatic PLA2 was found. The results suggest that the increased catalytic activity of PLA2 in sera of patients with septic fever results from synovial-type group II PLA2.