bluuebunny/crossref_metadata_2025_split huggingface dataset:
Superiority of Dynamic Over Static Reference Intervals for Intact, Midmolecule, and C-Terminal Parathyrin in Evaluating Calcemic Disorders
Authors: Lepage R , Whittom S , Bertrand S , Bahsali G , D'Amour P 
Published: January 2020

Abstract
We compared the clinical performance of assays of intact, C-terminal, and midmolecule parathyrin (PTH), when used with either a dynamic reference interval (based on the range of serum PTH concentrations observed in 35 healthy individuals during acute modifications of their blood calcium concentrations) or a gaussian (mean +/- 2 SD) interval derived from normocalcemic individuals. Dynamic intervals were substantially different from gaussian intervals, with half of the area delimited by the gaussian limits for calcium and intact PTH concentrations, and one-third for both C-terminal and mid-PTH assays, being outside the range of values observed during the dynamic tests. Use of the dynamic intervals increased the average clinical sensitivity of the three assays for detecting primary hyper- and hypoparathyroidism from 68% to 97% (and up to 100% for the intact and C-PTH assays). Even though only the intact PTH assay allowed complete separation between primary hyperparathyroid and nonparathyroidal hypercalcemic patients, the average proportion of patients correctly classified in this latter category was increased from 40% to 70% by the use of dynamic intervals. We conclude that gaussian reference intervals are largely responsible for the poor clinical sensitivity of many types of PTH immunoassays and that they should be replaced by dynamic reference intervals when evaluating calcemic disorders.
Parathyroid Hormone-Related Protein: Structure, Function, and Measurement
Authors: Burtis W J 
Published: January 2020

Abstract
Parathyroid hormone-related protein (PTHRP) is a 139- to 173-amino-acid protein with N-terminal homology to parathyroid hormone (PTH). Initially isolated from tumors from patients with humoral hypercalcemia of malignancy, PTHRP appears to be of far more widespread physiological importance. Its complex gene is expressed in a surprising diversity of tissues. The primary amino acid sequences of both the PTH-like and non-PTH-like regions of the protein are highly conserved across species. In addition to classical and nonclassical PTH-like activities of the N-terminal region, other biological functions have been ascribed, including augmentation of calcium transport by midregion PTHRP and potent inhibition of bone resorption by a C-terminal peptide. There is emerging evidence that the protein undergoes extensive processing, including glycosylation and defined proteolytic cleavages. Several region-specific immunoassays are now capable of measuring circulating concentrations of PTHRP in patients with humoral hypercalcemia of malignancy. Molar concentrations of different regions may differ by more than an order of magnitude, reflecting diversity in processing and (or) metabolism. By analyzing the results of these assays, taking into account the specificities of known endoproteases, one can hypothesize about some of the endoproteolytic cleavages that occur in PTHRP metabolism. Clinically, selected PTHRP assays can be very helpful in diagnosing PTHRP-mediated hypercalcemia, but are not yet sufficiently sensitive to accurately measure normal concentrations of the protein.
Simple Method for Correcting Total Protein in Plasma for Actual Fibrinogen Content
Authors: Bakker A J , Gorgels J P , Draaisma J , Jongendijk M , Altena L , Hamersma A , Weiland A 
Published: January 2020

Abstract
Using plasma instead of serum for routine chemistry analyses has many advantages. To overcome the disadvantage of inclusively measuring fibrinogen in the plasma total protein assay without changing the clinical significance of the total protein assay, we investigated the possibility of subtracting the actual amount of fibrinogen from the plasma total protein. The correlation between serum and plasma total protein was excellent (plasma total protein = 0.989 x serum total protein + 6.7 g/L; r = 0.969; n = 131; mean difference = 5.55 g/L; P &lt; 0.001). When the plasma total protein was corrected for the actual amount of fibrinogen, the correlation with serum total protein was equally good but the intercept was practically eliminated (corrected plasma total protein = 1.009 x serum total protein + 0.25 g/L; r = 0.985; n = 131; mean difference = 0.78 g/L; P = 0.47). The mean concentration of fibrinogen was 2.5 g/L (range: 1.38-3.62 g/L; n = 404) for blood donors, 3.6 g/L (n = 2707) for patients from the outpatient department, 4.6 g/L (n = 2023) for patients admitted to the hospital, and 6.6 g/L (n = 219) for patients whose concentration of C-reactive protein was &gt; 50 mg/L. We conclude that the plasma total protein result should be corrected for the actual amount of fibrinogen.
Two-Site Assays of Bone Gla Protein (Osteocalcin) Demonstrate Immunochemical Heterogeneity of the Intact Molecule
Authors: Deftos L J , Wolfert R L , Hill C S , Burton D W 
Published: January 2020

Abstract
We developed a panel of monoclonal antibodies to human bone gla protein (BGP; osteocalcin) peptides that span the linear sequence of the molecule, specifically BGP 1-12 (N-terminal), BGP 15-30 (midregion), and BGP 38-49 (C-terminal). These antibodies were evaluated in various combinations of two-site formats in studies of serum BGP concentrations. For clinical studies, we selected from a panel of antibodies the two most sensitive antibody pairs for the intact molecule (N-C); we also used a polyclonal RIA based on BGP-C. For the two-site format, we used two N-terminal antibodies, 029 and 052, adsorbed to polystyrene beads, and radioiodinated a C-terminal antibody, 663. The standard for each of the assays was purified human BGP. The following BGP serum concentrations (microgram/L, mean +/- SE) were measured with the various assays: by the 029-663 assay, results for normal subjects were 7 +/- 3, for patients with renal failure 25 +/- 8, and for patients with Paget disease 12 +/-4; by the 052-663 assay, the respective results were 22 +/- 4, 44 +/- 12, and 31 +/- 7; by the polyclonal assay, the results were 3 +/- 0.2, 13 +/- 2, and 5 +/- 1. The two intact (N-C) assays were significantly (P &lt; 0.01) correlated (r = 0.94), but their serum values differed by more than twofold in terms of the same BGP standard. The polyclonal assay significantly correlated with each of the intact assays (r = 0.83, 0.77), but it, too, gave different serum values for BGP. These studies demonstrate the immunochemical heterogeneity of circulating BGP, heterogeneity that is manifest even in immunoassays specific for the same region of the molecule.
Placental Alkaline Phosphatase: A Model for Studying COOH-Terminal Processing of Phosphatidylinositol-Glycan-Anchored Membrane Proteins
Authors: Amthauer R , Kodukula K , Udenfriend S 
Published: January 2020

Abstract
Placental alkaline phosphatase (PLAP) has been used as a model for studying the biosynthesis of the phosphatidylinositol-glycan (PI-G)-protein linkage in intact cells and in cell-free systems. However, for the study of processing in cell-free systems, a small protein devoid of glycosylation sites is preferable. A PLAP-derived cDNA was engineered that codes for a nascent protein (mini-PLAP) of 28 kDa in which the NH2- and COOH-termini are retained but most of the interior of PLAP is deleted. In vitro translation of mini-PLAP mRNA in the presence of rough microsomal membranes yields mature PI-G-tailed mini-PLAP. Processing of nascent mutant proteins occurs only when a small amino acid is located at the site of cleavage and PI-G attachment (omega site). Mutations adjacent and COOH-terminal to the omega site have revealed that the omega + 1 site is promiscuous in its requirements but that only glycine and alanine are effective at the omega + 2 site. Rough microsomal membranes from T cells deficient in PI-G biosynthesis do not support processing of mini-PLAP; addition of exogenous PI-G restores activity. Translocation of the proprotein, most likely requiring ATP and GTP, precedes COOH-terminal processing.
Decreased Abundance of Alkaline Phosphatase and Calbindin-D9K mRNAs in the Intestine of the Spontaneously Hypertensive Rat
Authors: Leetun D T , Bruns M E , Bruns D E 
Published: January 2020

Abstract
Alkaline phosphatase activity and calbindin-D9K immunoreactivity are decreased in the intestines of spontaneously hypertensive rats (SHRs). To investigate the potential role of altered gene expression in these decreases, we measured, by Northern blot analyses, the abundances of alkaline phosphatase and calbindin-D9K mRNAs in the proximal regions of the small intestines of 14-week-old SHR and control Wistar-Kyoto (WKY) rats. Alternate 4-cm segments of intestine were used for measurements of the proteins (0-4 cm, 8-12 cm, and 16-20 cm from pylorus, segments A1, B1, and C1, respectively) and mRNAs (4-8 cm, 12-16 cm, and 20-24 cm, segments A2, B2, and C2). Calbindin-D9K (immunoassay) was decreased in SHR vs WKY rats by 27%, 64%, and 67% in segments A1, B1, and C1, respectively (P &lt; 0.01); its mRNA was decreased to a similar extent (69%, 82%, and 80%, respectively; P &lt; 0.002 by analysis of variance). Alkaline phosphatase activity was decreased in SHRs by 58%, 54%, and 51% in segments A1, B1, and C1, respectively (P &lt; 0.01); the abundance of its 3.0-kb mRNA was decreased to a similar extent: 57%, 80%, and 69% in segments A2, B2, and C2, respectively (P &lt; 0.02). The mean decreases of the 2.7-kb mRNA of alkaline phosphatase were statistically significant (P &lt; 0.02) but smaller (38%, 40%, and 35%). The mean abundance of vitamin D receptor mRNA in the same animals was decreased slightly in SHR vs WKY rats (3%, 36%, and 20% in segments A2, B2, and C2, respectively), but the difference in the values was not statistically significant. Decreases in alkaline phosphatase activity and calbindin-D9K immunoreactivity may reflect decreased mRNA abundance and not decreased enzyme-specific activity or increased protein degradation.
Dextran Sulfate Complexes with Potassium Phosphate to Interfere in Determinations of High-Density Lipoprotein Cholesterol
Authors: Olmos J M , Lasunción M A , Herrera E 
Published: January 2020

Abstract
The interference of dextran sulfate with the colorimetric determination of free cholesterol causes an increase in the absorbance that is proportional to the dextran sulfate concentration in the sample. This makes estimation of the free cholesterol concentration unreliable in high-density lipoprotein-containing supernates obtained after plasma precipitation with dextran sulfate/MgCl2. Analysis of the absorption spectrum demonstrated that the absorbance increase was due to turbidity. We observed this effect with colorimetric reagents based on potassium phosphate buffer but not with those based on sodium phosphate or Tris buffers. This effect is ascribed to dextran sulfate because neither the omission of Mg2+ ions nor their chelation with EDTA prevented turbidity, whereas precipitation of dextran sulfate with Ba2+ counteracted this effect. Therefore, potassium phosphate-buffered reagents appear unsuitable for colorimetric lipid determinations in samples containing dextran sulfate.
Ratio of Serum Tartrate-Inhibitable Acid Phosphatase to Total Serum Protein in Benign Prostatic Hypertrophy and Prostatic Carcinoma
Authors: Petrovich George , Ursich-Jankovich Jasna , Prijovich Zeijko 
Published: January 2020

Abstract
The activity concentration and the specific activity (the ratio of enzyme activity to total serum protein) of the tartrate-inhibitable fraction of acid phosphatase [orthophosphoric monoester phosphohydrolase (acid optimum), EC 3.1.3.2; TIAP] were related to benign prostatic hypertrophy and to prostatic carcinoma. As expected, the TIAP activity concentrations assayed in the sera of patients with benign prostatic hypertrophy were within the range of those assayed in normal human sera. In contrast, the specific activities of TIAP determined in the sera of patients with benign prostatic hypertrophy were significantly higher than those determined in the control group. In the sera of prostatic carcinoma patients, both the TIAP activity concentrations and the TIAP specific activities differed significantly (F = 730) from the normal values.
Decreases in Apolipoprotein(a) after Renal Transplantation: Implications for Lipoprotein(a) Metabolism
Authors: Black I W , Wilcken D E 
Published: January 2020

Abstract
Serum concentrations of apolipoprotein(a) [apo(a)], the unique glycoprotein of lipoprotein(a), are increased in patients with end-stage renal failure. We prospectively studied serum apo(a) and other lipoproteins in 20 consecutive patients, ages 46 +/- 11 years, before and for six months after successful renal transplantation. All patients received cyclosporine, and no patient was treated for hyperlipidemia. The mean creatinine clearance increased from 7.5 mL/min before transplant surgery to 40.9 mL/min six months afterwards (P less than 0.001). Apo(a) decreased from a median of 403 units/L before transplantation to 184 units/L at one week (P less than 0.001) and was 170 units/L (P less than 0.001) at six months. For the assay used, 1 unit of apo(a) is equivalent to 1 mg of lipoprotein(a). In contrast, from baseline to six months, increases were found for low-density lipoprotein (LDL) cholesterol (P = 0.03), high-density lipoprotein cholesterol (P = 0.06), apo B (P = 0.07), and apo A-I (P = 0.01). The decrease in apo(a) in individual patients was significantly correlated with the increase in creatinine clearance (r = -0.48, P less than 0.001). The single patient who developed nephrotic syndrome after renal transplantation had marked increases in apo(a) (693-1595 units/L), apo B, and LDL cholesterol, which paralleled the degree of proteinuria. These findings suggest that abnormal renal function affects the regulation of lipoprotein(a) metabolism.
Prototype Application of a Robot in the Clinical Laboratory Enabling Fully Automated Quantification of Fecal Porphyrins
Authors: Minder E I , Vuilleumier J P , Vonderschmitt D J 
Published: January 2020

Abstract
Unpleasant specimens, sensitive analytes, and a lengthy chromatographic procedure were the main reasons we implemented fecal porphyrin analysis with a laboratory robot. We describe the system in detail and compare it with the same technique performed manually. The day-to-day variation of assays of standards was lower with the robot than with the manual operation: 8% (CV) for coproporphyrin I and 11% for protoporphyrin IX. We repeatedly analyzed a specimen from a healthy volunteer and determined that the specimen contained (in nmol/g dry wt) 7.1 (SD 0.7) for coproporphyrin I, 3.0 (SD 0.4) for coproporphyrin III, and 44.4 (SD 4.3) for protoporphyrin IX. Upper reference limits as measured in 20 healthy volunteers were 20 nmol/g dry wt for coproporphyrin I, 12 nmol/g for coproporphyrin III, and 80 nmol/g for protoporphyrin IX. We also present characteristic chromatograms for samples from various different porphyrias that exhibit abnormal fecal porphyrin excretion. Calculations of return on investment show that the robot, working at full capacity, is a profitable tool.
Effect of Sample Storage on the Assay of Lipoprotein(a) by Commercially Available Radial Immunodiffusion and Enzyme-Linked Immunosorbent Assay Kits
Authors: Craig W Y , Poulin S E , Forster N R , Neveux L M , Wald N J , Ledue T B 
Published: January 2020

Abstract
Lipoprotein(a) [Lp(a)] was measured by both a radial immunodiffusion (RID) kit from Immuno AG (Zurich, Switzerland) and a Tint Elize enzyme-linked immunosorbent assay (ELISA) kit from CytRx Biopool Ltd. (Umeå, Sweden) in serum samples that had been stored at -20 and -70 degrees C for six months. Storage temperature had no significant effect on the Lp(a) concentrations obtained by either method. After six months, mean Lp(a) degradation was 46% (95% confidence interval, 34-58%) with the RID kit; the ELISA data could not be compared between time points. In fresh sera, Lp(a) concentrations obtained by RID were 41% higher than by ELISA (because of differences in assay calibration materials), but in paired measurements of a set of 215 samples stored at -40 degrees C for an average of 10 years, Lp(a) concentrations were 62% lower by RID. This suggests that RID is more sensitive to the effects of long-term storage than is ELISA.
Performance of Proficiency Survey Samples in Two Immunoradiometric Assays of Human Growth Hormone and Comparison with Patients' Samples
Authors: Pringle P J , Jones J , Hindmarsh P C , Preece M A , Brook C G 
Published: January 2020

Abstract
The immunoradiometric assay (IRMA) used in our laboratory for the measurement of growth hormone (hGH; somatotropin) performed badly in the national proficiency survey program, the U.K. External Quality Assessment Scheme (EQAS). We compared our assay with another IRMA, which gave similar results for patients' samples and performed adequately in EQAS. The samples from EQAS are collected from patients with polycythemia and fall into two categories: those containing endogenous hGH and those supplemented with pituitary-derived hGH. Analysis of the two groups separately showed that the differences between the two IRMAS were in the measurement of the endogenous hormone. The reason for this appears to be a matrix effect related to the fact that the EQAS serum samples are collected from polycythemic patients.
Optimized Spectrophotometric Determination of Aldehyde Dehydrogenase Activity in Erythrocytes
Authors: Johnson R D , Bahnisch J , Stewart B , Shearman D J , Edwards J B 
Published: January 2020

Abstract
We describe a reliable and sensitive semiautomated spectrophotometric assay of aldehyde dehydrogenase (ALDH; EC 1.2.1.3) activity in erythrocytes. The hemolysate can be stabilized with sucrose, and the technique involves only microliters of hemolysate on a centrifugal analyzer. The use of microcolumns to remove interfering hemoglobin is avoided, and reproducibility of the assay has been improved by manipulating the inherent lactate dehydrogenase activity of erythrocytes by adding lactate and oxalate to the reaction mixture. These modifications have decreased the analytical imprecision of the assay, allowing a better appraisal of aldehyde dehydrogenase activity in erythrocytes as a biological marker of excess alcohol consumption. Erythrocytic ALDH activity was significantly less in 40 alcoholics than in 145 teetotallers (median activity 128 vs 219 mU/g of hemoglobin, respectively; P = 0.0001), indicating the potential of this assay as a useful marker of excess alcohol consumption.
Triple-Helical Capture Assay for Quantification of Polymerase Chain Reaction Products
Authors: Vary C P 
Published: January 2020

Abstract
This method for rapid, automated analysis of polymerase chain reaction (PCR) products makes use of PCR primers containing 5'-polypyrimidine sequences. Polypyrimidine-"headed" primers confer to the PCR product the ability to form triple helical complexes with a third polypyrimidine oligonucleotide. Third-strand oligonucleotides are modified to serve as either capture reagents or detection reagents for PCR products. Automated quantitative measurement of the PCR product is achieved by using latex bead-based fluorescence analysis. The use of triple-instead of double-helical interactions avoids the usual requirements of complex blocking reagents, time- and labor-intensive washing steps, and long times for color development. The method also provides rapid, sequence-specific capture and detection of PCR products without the need to denature the double-stranded PCR product. The assay is demonstrated with use of both PCR primer-derived and endogenous triple-helix-forming sequences resulting from PCR of several bacterial and viral target nucleic acids.
Measuring Ethanol in Blood and Breath for Legal Purposes: Variability between Laboratories and between Breath-Test Instruments
Authors: Jones A W , Beylich K M , Bjørneboe A , Ingum J , Mørland J 
Published: January 2020

Abstract
We determined the concentrations of ethanol in nearly simultaneous specimens of venous blood (BAC) and end-expired breath (BrAC) after healthy volunteers drank moderate amounts of alcohol. BAC was measured at two laboratories and BrAC was analyzed with two instruments (Intoxilyzer 5000) from the same manufacturer. The mean difference in BAC between laboratories was 0.0105 mg/g (SD 0.0219); 95% of the differences ranged from -0.0333 to 0.0543 mg/g. The mean difference in BrAC between instruments was 0.0153 mg/L (SD 0.0136), and 95% of the differences ranged from -0.0119 to 0.0425 mg/L. The coefficient of variation (CV) between laboratories was 2.9% compared with 4.5% between breath-test instruments. Venous BAC (y) and BrAC (x) were highly correlated (r = 0.978). However, when the Intoxilyzer instruments indicated that BrAC had reached zero, the actual BAC was 0.135 mg/g, according to the average forensic laboratory reports. The Intoxilyzer 5000 breath analyzers used in this study seem to have a constant analytical bias.
Acquired Hypolipoproteinemia
Authors: De Buyzere M , Delanghe J , Labeur C , Noens L , Benoit Y , Baert J , Rosseneu M 
Published: January 2020

Abstract
We present a six-year follow-up of a boy with a novel type of hypolipoproteinemia, with clinical and biochemical features distinct from classical hypoalphalipoproteinemias. There were abnormally low concentrations of total and high-density lipoprotein (HDL) cholesterol, apolipoprotein (apo) B, apo A-I, and apo A-II, and the phospholipids were decreased. The most striking abnormality was an extra fraction containing mainly phospholipids and apo A-I in the HDL3 subfraction. This fraction is reminiscent of concentric 20- to 50-nm-diameter lamellar phospholipid liposomes. Plasma lecithin:cholesterol acyltransferase activity was strongly decreased. We noted a persisting polyclonal hypergammaglobulinemia, hematological abnormalities (hemolytic anemia and thrombocytopenia), and a progressive splenomegaly. After the five-year follow-up, the patient had recurrent severe infections; moderate hematuria and proteinuria developed gradually. Treatment with corticosteroids and immunoglobulins improved thrombocytopenia and hypolipoproteinemia. These clinical and biochemical findings differ from those in the known primary and secondary hypo-alpha-lipoproteinemia syndromes. Although investigation of the relatives suggests a familial predisposition for hypo-alpha-lipoproteinemia, the subject's condition can be regarded as acquired.
Two-Site Monoclonal Antibody-Based Immunoradiometric Assay for Measuring Prostate Secretory Protein in Serum
Authors: Huang C L , Liang H M , Brassil D , Schellhammer P F , Rozzell M , Newhall K , Beckett M L , Wright G L 
Published: January 2020

Abstract
We developed a double-determinant immunoradiometric assay for measuring serum prostate secretory protein (PSP), using monoclonal antibodies (MAb) against two different epitopes: MAb PSP-19 was the capture antibody and MAb PSP-6 was the tracer antibody. Assay sensitivity was 0.1 microgram/L. Analytical recovery of PSP was 93.5-104.6%, whereas the intra- and interassay mean CVs were 4.2% and 6.9%, respectively. In 92 normal men, ages greater than 50 years, the mean PSP concentration was 5.7 micrograms/L, with 10 (10.9%) men having concentrations greater than 10 micrograms/L. In contrast, 20 of 49 (40.8%) patients with benign prostate hyperplasia (BPH; mean PSP concentration 9.4 micrograms/L) and 46 of 100 (46%) patients with prostate cancer (mean PSP concentration 22.2 micrograms/L) had PSP concentrations greater than 10 micrograms/L. Mean serum PSP concentrations of the BPH (P less than 0.05) and prostate cancer (P less than 0.01) groups were significantly different from those of age-matched normal men. In a small group of patients, serial PSP concentrations correlated with the clinical course during therapy. Thus, PSP may be a useful marker for evaluating patients with prostate cancer.