bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of cyclosporin G (NVa2 cyclosporin) in blood and plasma
Authors: Yatscoff R W , Honcharik N , Lukowski M , Thliveris J , Chackowsky P , Faraci C 
Published: January 2020

Abstract
We report here on the distribution of cyclosporin G (CsG), an analog of cyclosporin A, in whole blood. CsG has a temperature-dependent distribution between erythrocytes (RBCs) and plasma. After 30 min at 37 degrees C, the plasma/whole blood and plasma/RBC ratios were relatively constant (0.7-0.8) up to CsG at 1000 micrograms/L. At 5000 micrograms/L, this ratio increased to 1.0-1.1 for plasma/whole blood and 1.7 for plasma/RBC. The primary CsG metabolites GM1 and GM9 were sequestered within RBCs to a greater extent than was the parent drug. In whole blood, approximately 2% of CsG was bound to granulocytes, 6% to lymphocytes, and 50-55% to RBC, and 35-40% was found in the plasma fraction. The free fraction of the drug as determined by ultracentrifugation was 5-6% and 13-17% of total drug at 37 and 4 degrees C, respectively. In plasma the drug was primarily associated with high-density lipoprotein (50-60%) and to a lesser degree with low-density (20-30%) and very-low-density (10%) lipoproteins.
Laboratory diagnosis of medium-chain acyl-coenzyme A dehydrogenase deficiency by the amplification refractory mutation system
Authors: Tsai M Y , Schwichtenberg K , Tuchman M 
Published: January 2020

Abstract
We used the amplification refractory mutation system (ARMS)--a polymerase-chain-reaction-based method--to detect the 985 A-to-G mutation of the gene coding for the enzyme medium-chain acyl-CoA dehydrogenase (MCAD). The 985 A-to-G allele is thought to account for approximately 89% of the mutant alleles in this disorder and at least one copy was reported to be present in 98% of affected individuals. ARMS provided a simple and robust method that reliably identified the 985 A-to-G mutant allele in patients either homozygous or heterozygous for this allele. Combined with organic acid analysis, ARMS can provide definitive diagnosis for the great majority of the patients with MCAD deficiency. The method, therefore, should be useful in clinical laboratories involved with the diagnosis of inborn errors of metabolism.
Assessment of the role of G proteins and inositol phosphate production in the action of gonadotropin-releasing hormone
Authors: Hawes B E , Conn P M 
Published: January 2020

Abstract
The first step in gonadotropin-releasing hormone (GnRH) action involves the binding of GnRH to a plasma membrane receptor. Calcium has been implicated as a second messenger molecule. More recently, it has been suggested that the products of phosphoinositide metabolism may act as a second messenger for GnRH-stimulated release of luteinizing hormone (LH). To be considered a second messenger, however, a candidate molecule must meet three requirements: in the second messenger's presence, (a) GnRH should stimulate increased production of inositol phosphate; (b) inositol phosphate production, stimulated by any means, should provoke LH release; and (c) inhibition of inositol phosphate production should block GnRH-stimulated release of LH.
Simplified enzymatic assay of angiotensin-converting enzyme in serum
Authors: Groff J L , Harp J B , DiGirolamo M 
Published: January 2020

Abstract
We report a simple, enzymatic method for determining angiotensin-converting enzyme (ACE; EC 3.4.15.1) in serum. The proposed method features coupling an established reaction catalyzed by gamma-glutamyltransferase (GGT; EC 2.3.2.2) to the ACE reaction, which releases glycylglycine from the artificial substrate hippuryl-glycyl-glycine. The glycyl-glycine released by the ACE reaction becomes rate-limiting in the GGT reaction, in which it participates as a receptor substrate for a gamma-glutamyl group transferred from a donor substrate, L-gamma-glutamyl-3-carboxy-4-nitroanilide. The reaction releases 3-carboxy-4-nitroaniline, which is monitored spectrophotometrically at 410 nm. The resulting rate of change in absorbance is linearly related to the glycyl-glycine concentration and therefore to the activity of ACE. The linear range of the method extends from ACE values &lt; 50 to at least 1300 U/L of serum. Good precision is indicated by a low CV for replicate analyses (3.6% and 4.6% for within-run and day-to-day assays, respectively, for normal ACE activity, and 3.1% within-run for high ACE activity). Results also correlate well with those of an established colorimetric method (r = 0.978). The major advantages of the method are its procedural simplicity, limited cost, use of readily available reagents, applicability to isoenzyme studies, and adaptability to automation.
Behavior of tumor markers CA19.9, CA195, CAM43, CA242, and TPS in the diagnosis and follow-up of pancreatic cancer
Authors: Banfi G , Zerbi A , Pastori S , Parolini D , Di Carlo V , Bonini P 
Published: January 2020

Abstract
We compared the recently proposed tumor markers CA195, CA242, and CAM43 with a widely used antigen, CA19.9, and a circulating marker of cellular proliferation, TPS, to define their specificity, sensitivity, and cost-benefit ratio. The tumor markers were measured in 41 pancreatic carcinoma patients and in two control groups, the first comprising 19 patients with benign pancreatic diseases, the second comprising 41 healthy blood donors. Sensitivities were 79% for CA19.9, 57% for CA242, 60% for CAM43, 76% for CA195, and 98% for TPS. Specificities calculated for the group with pancreatic diseases were 60% for CA19.9, 84% for CA242, 95% for CAM43, 53% for CA195, and 22% for TPS. Specificities for the blood donor group were 100% for CA19.9, 93% for CA242, 98% for CAM43, 85% for CA195, and 88% for TPS. Positive values for the tumor markers appeared from second stage (Hermreck classification). Metastases, invasion of lymph nodes, and coupling of cancer-associated antigens did not significantly modify marker sensitivity. In pancreatic carcinoma, CA19.9 showed good sensitivity (79%) and high specificity (60-100%). In view of their own advantages (e.g., high specificity of CAM43, high sensitivity of TPS in recurrences) and limits (e.g., low sensitivity of CAM43, very low sensitivity of TPS), the other markers could be used alone or with CA19.9. Two pairs of tumor markers showed high similarity in our study: CA19.9 and CA195, and CAM43 and CA242.
Aberrant PO2 values in proficiency testing
Authors: Fonzi C E , Clausen J L , Mahoney J 
Published: January 2020

Abstract
We prospectively determined the frequency of aberrant vials of fluorocarbon/buffer used for proficiency testing of measurements of pH, PCO2, and PO2, using 20 duplicate vials from 12 lots of fluorocarbon/buffer and two arterial blood gas analyzers in eight reference laboratories. We defined aberrant vials as vials for which both duplicate measurements differed from the mean value of repeated measurements for the specific instrument (for each lot of testing materials) by &gt; 0.04 for pH, &gt; 10% of the mean or 3.0 mm Hg, whichever was greater, for PCO2; or &gt; 10% of the mean or 6 mm Hg, whichever was greater, for PO2. Four of 1620 vials (0.25%) were aberrant, all based on PO2 measurements (&lt; 70 mm Hg); all would have failed in both American/California Thoracic Societies and College of American Pathologists proficiency programs. The average intra-instrument SDs of repeated measures (range of mean values: pH, 7.181-7.631; PCO2, 12.7-65.9; PO2, 32.5-150.1) were 0.0055 for pH, 0.67 mm Hg for PCO2, and 1.65 mm Hg for PO2. Deliberate contamination of the fluorocarbon emulsion with room air, as might occur during sampling from the vial, indicated that only minor increases in PO2 (e.g., 1.0 mm Hg at PO2 of 56 mm Hg) occur when samples are aspirated. Larger increases in PO2 (mean 7.1 mm Hg at a PO2 of 66 mm Hg) occurred when the syringe samples were contaminated with room air. We conclude that isolated aberrant measurements of PO2 in blood gas proficiency testing attributable to vial contents can occur, but the frequency is very low.
Monoclonal antibody-based immunoenzymometric assays of retinol-binding protein
Authors: Pereira A B , Nishida S K , Vieira J G , Lombardi M T , Silva M S , Ajzen H , Ramos O L 
Published: January 2020

Abstract
Retinol-binding protein (RBP) is a low-molecular-mass protein (21 kDa), easily filtered in renal glomeruli and very efficiently reabsorbed by the proximal convoluted tubules (PCTs). In PCT dysfunction, high concentrations of RBP are found in urine. Several methods have been used to determine RBP in serum or urine. We describe the production, selection, labeling, and utilization of anti-RBP monoclonal antibodies in two- or one-step immunoenzymometric assays for the determination of RBP. The one-step assay has good precision, with within-run and between-run CVs &lt; 6.6% and 5.9%, respectively. Comparison with radial immunodiffusion (x) showed good agreement: y = 0.068 mg/L + 0.899x (n = 24). Comparison between the one-step (y) and two-step (x) versions of the assay also showed a very good correlation: y = 212 micrograms/L + 0.910x. The one-step assay has been adopted for routine work; it detects transthyretin-bound as well as free RBP and may have clinical usefulness in evaluating the functional status of PCTs.
Rate nephelometric assay of serum lipoprotein(a)
Authors: Gillery P , Arthuis P , Cuperlier C , Circaud R 
Published: January 2020

Abstract
This nephelometric assay of serum lipoprotein(a) [Lp(a)] is characterized by the use of a specific antibody to generate a high rate of light-scatter formation and the elimination of nonspecific reactions from serum samples by diluting samples in phosphate-buffered saline containing polymer enhancer polyethylene glycol (PEG), 40 g/L, and detergent before the assay. We reacted 100 microL of sixfold-diluted serum in 500 microL of buffer containing PEG with 42 microL of pure polyclonal rabbit antiserum (Dakopatts) directed against human Lp(a) and monitored the reaction by rate nephelometry with the Array Protein System nephelometer (Beckman). The standard curve for the reaction was linear in the Lp(a) range 10-1280 mg/L; antigen excess occurred between 1300 and 1400 mg/L. Calibration was performed with serial dilutions of a standard serum. Precision studies showed within-run and between-run CVs of &lt; 2.1% and 6.9%, respectively. The nephelometric results (y) for 100 serum samples were highly correlated with those obtained by radial immunodiffusion (x) calibrated with the same materials: y = 1.07 (+/- 0.03) x - 16.2 (+/- 8.1) mg/L (r = 0.974, P &lt; 0.001). Storing serum for 3 weeks at 4 degrees C or 3 months at -80 degrees C did not affect the results.
Low-molecular-mass proteinuria as a marker of proximal renal tubular dysfunction in normo- and microalbuminuric non-insulin-dependent diabetic subjects
Authors: Holm J , Hemmingsen L , Nielsen N V 
Published: January 2020

Abstract
We determined the urinary excretion, expressed as the protein/creatinine ratio (morning urines), of albumin (a marker of glomerular dysfunction) and retinol-binding protein (RBP; a low-molecular-mass protein marker of tubular proteinuria) in 102 non-insulin-dependent diabetic patients. There was a statistically significant (P &lt; 0.0001) correlation (rho = 0.38) between the urinary excretion values of the two proteins. The population could be divided into four subgroups: 32 with normal excretion values, 15 with above-normal urinary excretion of RBP, 24 with above-normal urinary excretion of albumin, and 31 patients with above-normal urinary excretion of both proteins. No patients had above-normal serum creatinine concentrations or above-normal serum RBP concentrations. This seems to exclude "tubular overflow proteinuria" as the cause of the increased urinary excretion of RBP seen in some patients with non-insulin-dependent diabetes. Our data suggest the presence of a state of proximal tubular dysfunction in these patients.
Rapid determination of serum myoglobin with a routine chemistry analyzer
Authors: Bakker A J , Boymans D A , Dijkstra D , Gorgels J P , Lerk R 
Published: January 2020

Abstract
A turbidimetric immunoassay system (Turbitime system, Behringwerke AG) allows rapid determination of myoglobin in serum. We adapted the reagents for this myoglobin assay (Turbiquant myoglobin) for use with a Hitachi 717 analyzer. No high-dose hook effect was observed up to 15,000 micrograms/L. Interassay CVs were 4.6% (mean = 72.0 micrograms/L; n = 9) and 2.5% (mean = 365.6 micrograms/L; n = 11). The calibration curve was stable for at least 1 month. Hemolysis did not interfere, and turbidity from lipemia interfered only when absorbance exceeded 2.0 A. Results of this method (y) correlated well with those by the Turbitime method (y = 1.256x - 44.1 micrograms/L; n = 91; r = 0.991) and by a commercially available radioimmunoassay (Byk-Sangtec; y = 0.739x - 42.2 micrograms/L; n = 94; r = 0.991). The upper limit (95th percentile) of the reference interval for myoglobin was estimated at 57.9 micrograms/L. The positive predictive value for results of myoglobin at admission was 89% with this upper reference limit and 99% with 100 micrograms/L, whereas the negative predictive value was about 60% for both limits.
International Federation of Clinical Chemistry standardization project for measurements of apolipoproteins A-I and B. III. Comparability of apolipoprotein A-I values by use of international reference material
Authors: Marcovina S M , Albers J J , Henderson L O , Hannon W H 
Published: January 2020

Abstract
In the third phase of the International Federation of Clinical Chemistry (IFCC) study for the standardization of apolipoprotein (apo) measurements, the preparation SP1-01, selected as the candidate international reference material for apo A-I, was investigated for its ability to transfer an accuracy-based value to the immunoassay calibrators and to produce comparability of the values for patients' samples. An apo A-I value of 1.50 g/L (SD 0.08 g/L) was assigned to SP1-01 by a highly standardized RIA calibrated with purified apo A-I for which the mass value had been determined by amino acid analysis. According to a common detailed protocol, the participants transferred the mass value from SP1-01 to the calibrator of each method. To confirm that uniformity of calibration ensures comparability of the values over a wide range of apo A-I values, each laboratory analyzed 50 fresh-frozen samples from individual donors, using an approach similar to that adopted by the Cholesterol Reference Laboratory Network. The consensus mean value for each sample was in excellent agreement with the value assigned by the Northwest Lipid Research Laboratories, with the average absolute bias between assigned and consensus value being 0.01 g/L. The among-laboratory CV on each of the 50 samples ranged from 2.1% to 5.6% (mean 3.6%), demonstrating that comparable apo A-I results can be obtained by a variety of immunochemical methods through the use of certified reference material. Based on the results obtained in these studies, SP1-01 has been approved as Apolipoprotein A-I International Reference Material by the World Health Organization.
Assessment of copper status: effect of age and gender on reference ranges in healthy adults
Authors: Milne D B , Johnson P E 
Published: January 2020

Abstract
We measured major indices related to copper nutritional status in 55 men and 86 women between ages 20 and 83 years who were in apparent good health. Plasma copper concentrations and both immunoreactive and enzymatically measured ceruloplasmin were significantly higher in women than in men and were higher in women taking oral contraceptives. Plasma copper, immunoreactive ceruloplasmin, and cytochrome-c oxidase in platelets and mononucleated leukocytes tended to increase with age. The ratio of enzymatic to immunoreactive ceruloplasmin, erythrocyte superoxide dismutase, and 67Cu uptake by erythrocytes were not significantly affected by either age or gender. Thus, factors other than copper nutriture--such as age, gender, and hormone use--need to be considered when using many of these indicators to evaluate copper nutritional status.
Childhood porphyrias: implications and treatments
Authors: Badcock N R , O'Reilly D A , Zoanetti G D , Robertson E F , Parker C J 
Published: January 2020

Abstract
In describing the clinical, biochemical, and family findings in five children with porphyria, we examine initial treatments and, where appropriate, the effectiveness of long-term therapy. We note that porphyria diagnosis, particularly in childhood, relies heavily on specialist laboratory investigations. Because disease expression in some porphyrias requires exposure to precipitating factors, it may be prevented or delayed by their avoidance.
Chemistry with confidence: should Clinical Chemistry require confidence intervals for analytical and other data?
Authors: Henderson A R 
Published: January 2020

Abstract
Confidence intervals are not commonly provided with analytical or other data reported in Clinical Chemistry although P values are. However, confidence intervals provide an explicit demonstration of the direction and magnitude of uncertainty and are intuitively easy to grasp, unlike P values. It is therefore argued that the Journal should adopt a policy requiring the provision of confidence intervals. Such a policy would improve the statistical rigor of Journal reports.
Determination of one thousandth of an attomole (1 zeptomole) of alkaline phosphatase: application in an immunoassay of proinsulin
Authors: Cook D B , Self C H 
Published: January 2020

Abstract
Enzyme amplification has proved to be a highly sensitive quantification technique for immunoassays. We have shown that by using a fluorescent end-point, even more sensitive enzyme amplification assays can be generated than hitherto reported. We describe some general properties of this system and demonstrate its application in an assay for human proinsulin in plasma. The detection system can be used to measure less than one thousandth of an attomole (1 zeptomole) of alkaline phosphatase, equivalent to about 350 molecules of alkaline phosphatase per well of a microtiter plate. We have used this system to construct a proinsulin assay with a sensitivity of 0.017 pmol/L.
Cardiac-specific immunoenzymometric assay of troponin I in the early phase of acute myocardial infarction
Authors: Larue C , Calzolari C , Bertinchant J P , Leclercq F , Grolleau R , Pau B 
Published: January 2020

Abstract
The screening by immunoenzymometric assay (IEMA) of 784 monoclonal antibody (MAb) combinations resulted in the selection of an optimal pair of MAbs for measuring human cardiac troponin I (TnI). Using a one-step IEMA described here, we were able to detect TnI within the range of 0.2-20 micrograms/L in 30 min at room temperature. No cross-reactivity was observed with the skeletal isoforms of troponin up to a concentration of 500 micrograms/L. This assay was used to measure cardiac TnI in the plasma of 43 patients with acute myocardial infarction (AMI). TnI was detected relatively early after the onset of chest pain (4.3 +/- 2.1 h, mean +/- SD); the peak occurred after 12.2 +/- 4.6 h in a population that had undergone fibrinolysis. TnI disappearance was generally observed between 5 and 9 days after the onset of chest pain. No cardiac TnI could be detected in 145 healthy donors or in a control group of 6 patients (with skeletal damage or rhabdomyolysis). This assay allows a specific diagnosis of AMI in its early acute phase, with a high diagnostic specificity and sensitivity.
In vitro effect of elastase and cathepsin G from human neutrophils on creatine kinase and lactate dehydrogenase isoenzymes
Authors: Stark J A , Henderson A R 
Published: January 2020

Abstract
The polymorphonuclear granulocyte, or neutrophil, has been implicated as a mediator of tissue-destructive events because it releases the preformed proteolytic enzymes elastase and cathepsin G, and, as a result of myeloperoxidase action, hypochlorous acid. We show that elastase inactivates and fragments creatine kinase isoenzymes CK-2 and CK-3, and, to a lesser extent, lactate dehydrogenase (LD) isoenzyme LD-1, whereas cathepsin G acts only on CK-2. Both neutrophil enzymes act on LD-3. The course of inactivation was followed by measuring the loss of catalytic activity at 37 degrees C. The evidence for fragmentation was obtained by gel filtration; electrophoresis after sample treatment with sodium dodecyl sulfate and 2-mercaptoethanol was less satisfactory for this purpose. Hypochlorous acid inactivates CK activity by about 75% at concentrations as low as 8 mumol/L and totally at concentrations &gt; 140 mumol/L, whereas LD activity is not affected until concentrations exceed 200 mumol/L. After a myocardial infarction, the number of neutrophils increases; they are triggered and concentrate around damaged myocardial tissue. Our data suggest that neutrophils may inactivate and fragment "cardiac" enzymes released from such damaged tissue.
Can medical decisions be standardized? Should they be?
Authors: Werner M 
Published: January 2020

Abstract
After a variety of regulatory and payment schemes have failed to stem the rising tide of health care cost, the Omnibus Budget Reconciliation Act of 1989 mandates the creation of a system of decision rules called practice parameters for appropriate medical action in many circumstances. A large body of practice guidelines already exists, but lacks the internal coherence required of a policy tool. Professional organizations therefore have developed attributes to achieve uniform style. However, little has been said or published about the constraints that might be imposed on the structure and content of an efficient and coherent system. The arguments presented here lead to the following conclusions: (a) process control is an inefficient tool to manage outcome--standards should reflect product control; (b) guidelines that proscribe are more likely to be supported by scientific data and consensus than those that prescribe; (c) the decision thresholds contained in such directives are policy choices rather than scientific imperatives; (d) neither decision analysis nor artificial intelligence is likely to readily influence medical decisions; and (e) as suggested by operations research, the development of practice parameters should concentrate on issues of therapeutic management in preference to issues of diagnostic activity.
Polymorphism of apolipoprotein E, lipoprotein(a), and other lipoproteins in children with type I diabetes
Authors: Salzer B , Stavljenić A , Jürgens G , Dumić M , Radica A 
Published: January 2020

Abstract
We assessed the effect of particular apolipoprotein (apo) E phenotypes, lipoprotein(a) [Lp(a)], and other lipoproteins on the development of dyslipoproteinemia in 450 patients with type I diabetes, ages 13-14 years. The control group consisted of 450 healthy school children of both sexes, ages 13-14 years. Both groups were found to be normolipidemic, but the concentration of Lp(a) was significantly (P &lt; 0.05) higher in the diabetic children than in the control group. Apo E 3/2 and apo E 4/4 phenotypes were more frequent in the group of diabetics. Diabetics with the apo E 3/3 phenotype had higher concentrations of very-low-density lipoprotein (VLDL) and Lp(a), and lower concentrations of low-density lipoprotein (LDL) than the apo E 3/3 nondiabetics. For apo E 3/2 phenotypes, total cholesterol, LDL cholesterol, LDL, apo A-I, and Lp(a) concentrations were higher in the diabetic children than in the control group; for apo E 4/3 phenotypes, this was true for triglycerides and VLDL cholesterol. The distribution of Lp(a) lipoprotein concentrations between 0.01 and &gt; 0.5 g/L indicated a more frequent occurrence of higher Lp(a) values in diabetic children than in the control group. Results of this study indicate that an increased concentration of Lp(a) lipoprotein and apo E 3/2 and apo E 4/3 phenotypes contribute to the expression of dyslipoproteinemia in type I diabetes in childhood.