bluuebunny/crossref_metadata_2025_split huggingface dataset:
New decision limits and quality-control material for detecting human chorionic gonadotropin misuse in sports
Authors: Laidler P , Cowan D A , Hider R C , Kicman A T 
Published: January 2020

Abstract
Male athletes may administer human chorionic gonadotropin (hCG) to enhance performance. Despite imposing a ban on hCG doping, the International Olympic Committee has no recommended procedure to confirm the presence of hCG. Our aim was to establish a limit for hCG in urine above which a sample may be considered positive. We measured hCG concentrations in urine samples from 1400 men with the Serono MAIAclone IRMA. Statistical evaluation of the results gave a "far outside" value [75th percentile + (3 x interquartile range)] of 5.0 IU/L; greater values are extremely unusual. Immunoreactive material in urine samples from a reference group of 120 noncompeting individuals was concentrated about sevenfold by centrifugal ultrafiltration; all these concentrated samples gave assay values &lt; 5.0 IU/L. To ensure with the greatest possible degree of certainty that no false-positive result is reported, we propose a decision limit of 10 IU/L in nonconcentrated ultrafiltered samples. We also prepared quality-control material to contain hCG at 10 IU/L. This material provides a decision limit above which, after confirmatory procedures, a sample should be considered positive. This should help establish comparability of results among laboratories testing for sports drugs.
Mechanisms of carcinogenesis and individual susceptibility to cancer
Authors: Venitt S 
Published: January 2020

Abstract
The population can be divided into four groups, or "oncodemes," depending on the relative contributions of environment and genetics to their risk of cancer. These oncodemes are: 1) background (random mutations in normal people); 2) environmental (environmental carcinogens acting on normal people); 3) environmental/genetic (environmental carcinogens acting on genetic susceptibility); and 4) genetic, with genetic susceptibility being more important than environmental exposure. Most cancer probably occurs in oncodemes 2 and 3. However, the contribution that genetic susceptibility to cancer makes to the total cancer burden is unknown. Genetic susceptibility may be important in occupational settings, where exposure to carcinogens is presumed to be restricted to concentrations believed to confer "acceptable" risks. This approach takes no account of individual susceptibility. The range over which metabolic polymorphisms exert their effects suggests that differences in pharmacogenetics between individuals may be important in occupational carcinogenesis. If this range were extrapolated to risk of human disease, at a given exposure one person might be 10-200 times more sensitive than another. Several metabolic polymorphisms have been linked to susceptibility to cancer. For some of these polymorphisms, genes have been cloned and genotypic tests based on use of the polymerase chain reaction have been developed. Limited data suggest that the effects of these polymorphisms on human cancer are complex. The genotypic testing of individuals occupationally exposed to carcinogens may provide firmer information on the relative contributions of nature and nurture on chemically induced cancer. The use to which such information is put demands wide debate.
Assessment of copper nutritional status
Authors: Milne D B 
Published: January 2020

Abstract
Despite increased interest in the role of copper deficiency in clinical problems and an increased understanding of the physiological roles of copper, the diagnosis of a marginal deficiency has not been perfected. The use of non-standardized procedures and the effects of factors other than copper nutriture have impeded identification of the "ideal" indicator of copper nutritional status in adult humans. The specific activity of copper enzymes, or of copper-containing enzymes in blood cells, such as erythrocyte superoxide dismutase and platelet or leukocyte cytochrome c oxidase, may be a better indicator of metabolically active copper stores than the serum concentration of copper or ceruloplasmin, because the enzyme activities are sensitive to changes in copper stores and are not as sensitive to factors not related to copper nutriture. A single index, such as serum copper concentration, is inadequate for assessing the total body copper nutriture of an individual and must be supported by corroborating evidence.
Pentane and isoprene in expired air from humans: gas-chromatographic analysis of single breath
Authors: Mendis S , Sobotka P A , Euler D E 
Published: January 2020

Abstract
Both pentane and isoprene are excreted in human breath. Although pentane is considered an index of lipid peroxidation, the significance of isoprene is unknown. Having a similar boiling point, these two hydrocarbons are difficult to separate by gas chromatography. We separated pentane from isoprene on both a Poraplot Q and a Poraplot U column, injecting single-breath samples directly into a gas chromatograph. The breath samples were pressurized to 800 mmHg to increase the amount of sample volume delivered to the column. In a group of 43 healthy volunteers, the concentrations of end-expiratory pentane and isoprene were 0.57 +/- 0.3 and 7.05 +/- 3.53 nmol/L, respectively. There was a significant linear correlation (r = 0.57, P &lt; 0.0001) between age and pentane concentration in expired air; isoprene showed no correlation with age or pentane concentrations. The age-related increase in pentane production suggests that oxidative stress may play a role in the aging process in humans. The method described should allow for rapid, inexpensive, serial measurement of expired pentane and isoprene.
Time-resolved immunofluorometric assay of trypsin-2 complexed with alpha 1-antitrypsin in serum
Authors: Hedström J , Leinonen J , Sainio V , Stenman U H 
Published: January 2020

Abstract
We developed a sensitive time-resolved immunofluorometric assay (IFMA) for trypsin-2 complexed with alpha 1-antitrypsin (AAT). We used a trypsin-2-specific monoclonal antibody on the solid phase and a europium-labeled polyclonal antibody to AAT as tracer. The detection limit is 0.05 microgram/L and the range of linearity extends to 100 micrograms/L. We compared the clinical utility of the trypsin-2-AAT assay with that of free trypsinogen-2 and amylase in serum by studying 120 healthy subjects, 29 patients with acute pancreatitis, 11 with extrahepatic biliary obstruction, and 34 with acute abdominal disorders of extrapancreatic origin. In patients with acute pancreatitis the median concentration of trypsin-2-AAT in serum was 59-fold that in healthy controls, 42-fold that in patients with biliary obstruction, and 33-fold that in patients with acute abdominal disorders of extrapancreatic origin. These differences are greater than those for trypsinogen-2 (19-, 20-, and 28-fold, respectively) and amylase (5.4-, 6.5-, and 5.4-fold, respectively). Compared with the assays of free trypsinogen-2 and amylase, our assay of trypsin-2-AAT improved the clinical specificity for acute pancreatitis by eliminating false-positive results in our control groups. Increased concentrations of trypsin-2-AAT and trypsinogen-2 were also observed in patients with chronic renal failure undergoing dialysis.
Nanotechnology: Basic Concepts and Definitions
Authors: Kaehler Ted 
Published: January 2020

Abstract
Molecular nanotechnology is an engineering discipline in which the goal is to build devices and structures that have every atom in the proper place. By means of this general purpose material-processing technology it will be possible to build almost any rigid, covalently bonded structure. Identical parts will be truly identical, enabling energy conversion and computation systems to have extremely high performance and reliability. Assembly will be done by mechanosynthesis, the process of holding two reactive molecules in contact with each other in a controlled orientation. Synthesis will be done on nanoscale assembly lines called molecular mills, where systems of moving belts will press individual molecules together and catalyze 106 reactions/s per station. High-performance mechanical computers will use moving rods to block the motion of other rods. The most important physical limit will be radiation damage. Without redundancy, a subsystem lasting 100 years will be limited to 106 nm3.
Effect of red wine ingestion on the antioxidant capacity of serum
Authors: Whitehead T P , Robinson D , Allaway S , Syms J , Hale A 
Published: January 2020

Abstract
Aerobic metabolism in biological systems produces reactive oxygen species, and defense against such prooxidants requires antioxidant activity, e.g., predominantly vitamins C and E in serum. Recently, flavonoids (polyphenols occurring widely in plants) have been investigated in vitro for their antioxidant activity; whether they are absorbed after ingestion is not clear. Using a chemiluminescent assay of serum antioxidant capacity (SAOC), we have studied the effects in normal individuals of ingesting red wine, white wine, and high doses of vitamin C. In nine subjects who ingested 300 mL of red wine, the mean SAOC was increased by 18% after 1 h and by 11% at 2 h. The same amount of white wine produced 4% and 7% increases, respectively. The ingestion of 1000 mg (5.7 mmol) of ascorbic acid by four subjects increased their mean SAOC by 22% at 1 h and by 29% at 2 h. An in vitro comparison of red wine, white wine, and various fruit juices showed the high antioxidant capacity of red wine in addition to its ability to increase the antioxidant capacity of serum in vivo. The antioxidant effects of various flavonoids and other polyphenols were also studied.
Rapid diagnosis of maple syrup urine disease in blood spots from newborns by tandem mass spectrometry
Authors: Chace D H , Hillman S L , Millington D S , Kahler S G , Roe C R , Naylor E W 
Published: January 2020

Abstract
We report a new method for the diagnosis of maple syrup urine disease (MSUD) from dried blood spots on newborn screening cards based on tandem mass spectrometry (MS-MS). The mean +/- SD concentration of Leu plus Ile in normal newborns was 151 +/- 47 mumol/L (n = 1096); for Val, 131 +/- 58 mumol/L (n = 791). SDs were lower when the concentrations of these amino acids were expressed relative to that of Phe. The mean ratio for Leu + Ile to Phe was 2.5 +/- 0.49; for Val to Phe, 2.18 +/- 0.51. These results compare well with values previously reported in the literature. With these criteria, samples from a collection categorized by a bacterial inhibition assay as normal or falsely positive for MSUD were normal by MS-MS [(Leu + Ile): Phe &lt; 5.0]. Samples from confirmed MSUD patients were categorized as abnormal [(Leu+Ile): Phe &gt; 9.0] by MS-MS.
Solubility of silver sulfadiazine in physiological media and relevance to treatment of thermal burns with silver sulfadiazine cream
Authors: Tsipouras N , Rix C J , Brady P H 
Published: January 2020

Abstract
Silver sulfadiazine cream has been a standard treatment for burns over the past two decades. Although many studies have described the phenomenon of silver absorption from burn wounds treated with silver sulfadiazine, they failed to examine the chemistry underlying the absorption process: Silver chloride was assumed to form at the burn wound and absorption of silver was believed to be negligible. Here we have developed chemical model systems to investigate the interactions of silver sulfadiazine and silver chloride in direct contact with synthetic serum electrolyte solution (SSES), with SSES plus endogenous ligands or beef blood plasma, and with human serum. The results indicate that silver absorption from an acute burn site can be significant, because human serum is capable of solubilizing silver. This finding is of concern, given the potential for silver toxicity as a direct consequence of applying silver sulfadiazine to extensive burn wounds.
Intestinal strontium absorption: from bioavailability to validation of a simple test representative for intestinal calcium absorption
Authors: Sips A J , van der Vijgh W J , Barto R , Netelenbos J C 
Published: January 2020

Abstract
Calcium absorption tests have rarely been validated for being representative for absolute bioavailability (true absorption) or for intraindividual variation. Therefore, we investigated the reproducibility of the absolute bioavailability of strontium chloride, a marker for intestinal calcium absorption, in healthy male volunteers (n = 8) by measuring the area under the plasma strontium concentration-time curve after oral and intravenous administration of strontium. Subsequently, we selected a simple test variable as being representative of absolute bioavailability. The mean absolute bioavailability (+/- SD) was 25% +/- 7%. The best test variable appeared to be the fractional absorption at 240 min (Fc240) after oral intake, which demonstrated the highest correlation with absolute bioavailability (r = 0.66). The intraindividual variations of the data for this variable and for the absolute bioavailability are similar to those described for various absorption tests based on the use of calcium isotopes. Thus, the Fc240 of strontium offers the potential of a simple clinical test for use as a measure of intestinal calcium absorption and its modulation.
Serum bilirubin and risk of ischemic heart disease in middle-aged British men
Authors: Breimer L H , Wannamethee G , Ebrahim S , Shaper A G 
Published: January 2020

Abstract
The possibility that low concentrations of serum bilirubin may be associated with increased risk of ischemic heart disease has been examined in a prospective study of 7685 middle-aged British men. During 11.5 years there were 737 major ischemic heart disease (IHD) events. A U-shaped relationship was observed between serum bilirubin and risk of IHD. Low bilirubin was associated with several cardiovascular risk factors, in particular smoking, low concentrations of high-density lipoprotein cholesterol, low forced expiratory volume in 1 s, and low serum albumin. The U-shaped relationship persisted even after adjusting for several risk factors. Compared with men in the lowest fifth of the distribution (bilirubin &lt; 7 mumol/L), those in the middle range (8-9 mumol/L) showed a 30% reduction in relative risk [RR = 0.68 (95% confidence intervals 0.51-0.89)] in IHD, whereas men in the top fifth (&gt; 12 mumol/L) showed similar risk to the lowest fifth [RR = 0.99 (95% confidence intervals 0.73-1.34)], which persisted after exclusion of men with bilirubin &gt; 17 mumol/L. The significance of this U-shaped relationship is unclear, but it could be interpreted as support for the role of endogenous antioxidants in the etiology of IHD.
Composition of interstitial fluid
Authors: Fogh-Andersen N , Altura B M , Altura B T , Siggaard-Andersen O 
Published: January 2020

Abstract
In several previous experiments to determine the composition of interstitial fluid, the results varied depending on the collecting technique, and the electrolyte concentrations differed from those of a hypothetical ultrafiltrate of plasma. In our approach, since a change of position from standing to supine is accompanied by hemodilution with interstitial fluid, we used the changes in hematocrit and composition of plasma in 20 subjects before and after lying down to calculate the composition of added interstitial fluid. The estimated protein concentration was 20.6 g/L, and the concentrations of total calcium and magnesium were low, in accord with a lower concentration of protein-bound calcium and magnesium. The activity of free cations was also lower, in agreement with a Donnan equilibrium potential of 1 mV across the endothelium. The concentration of leukocytes and platelets decreased according to the hemodilution, implying no escape or mobilization of these elements.
Monoclonal antibody assay for measuring bone-specific alkaline phosphatase activity in serum
Authors: Gomez B , Ardakani S , Ju J , Jenkins D , Cerelli M J , Daniloff G Y , Kung V T 
Published: January 2020

Abstract
Alkaline phosphatase (ALP) is present in human serum in the form of several isoenzymes. The two major circulating ALP isoenzymes, bone and liver, are difficult to distinguish because they are the products of a single gene and differ only by posttranslational glycosylation. Quantitative measurement of bone ALP (BAP) activity in serum can provide an index for the rate of bone formation. Furthermore, increased BAP activity in serum is indicative of bone disorders. We describe a method in which serum samples are added to a microtiter plate coated with monoclonal anti-BAP antibody and incubated 3 h at room temperature. After the unbound materials are washed off, the bound BAP activity is measured by adding p-nitrophenyl phosphate substrate. The assay demonstrated no cross-reactivity to intestinal or placental ALP and only 3-8% cross-reactivity to liver ALP. The intraassay (n = 21) CVs were 3.9-5.9%, and interassay (n = 8) CVs were 4.4-7.0%. Comparisons of the assay (y) with an IRMA (x) and a wheat germ agglutinin precipitation method (x') gave regression equations of y = 1.32x-6.4, r = 0.99, and y = 1.41x' + 4.8, r = 0.99. The assay detected increased BAP in sera from patients with osteoporosis, Paget disease, osteomalacia, or primary hyperparathyroidism.
Effect of aging on susceptibility of low-density lipoproteins to oxidation
Authors: Schmuck A , Fuller C J , Devaraj S , Jialal I 
Published: January 2020

Abstract
According to the Adult Treatment Panel of the National Cholesterol Education Program, age is a major risk factor for heart disease. To assess the relation between age and LDL oxidizability, we studied copper-mediated LDL oxidation in 13 healthy elderly subjects (&gt; 59 years) and 13 sex-matched healthy young controls (&lt; 30 years). Total and LDL-cholesterol concentrations were increased in elderly subjects. The time course of copper-mediated LDL oxidation showed no significant differences between the two groups as assessed by formation of conjugated dienes, lipid peroxides, and apolipoprotein B fluorescence. Kinetics of LDL oxidation as quantified by lag time, oxidation rate, and maximal oxidation were not significantly different between the elderly and young groups. Although the concentrations of 16:0, 18:0, 18:1, 18:3, and 20:4 and total polyunsaturated fatty acids were significantly higher in the elderly group, LDL fatty acid concentrations were similar in both groups. Lipid-standardized alpha-tocopherol, beta-carotene, and ascorbate concentrations were not significantly different between the two groups. The findings of the present study suggest that in the healthy elderly, LDL oxidation may not be a crucial mediator for atherogenesis.
Serum concentrations of apolipoprotein A-I, apolipoprotein B, and lipoprotein(a) in a population sample
Authors: Leino A , Impivaara O , Kaitsaari M , Järvisalo J 
Published: January 2020

Abstract
Serum concentrations of apolipoprotein (apo) A-I, apo B, and lipoprotein(a) [Lp(a)] were studied with respect to age and sex in a Finnish population sample of 575 subjects (286 men and 289 women), ages 27-67 years. Apo A-I and apo B were measured with an immunoturbidimetric method calibrated against WHO International Reference Materials. Lp(a) was measured by RIA. Apo A-I and apo B concentrations were almost normally distributed (apo A-I: mean 1.38 g/L vs median 1.34 g/L for men, and 1.58 g/L vs 1.55 g/L for women; apo B: mean 1.21 g/L vs median 1.20 g/L for men and 1.09 g/L vs 1.05 g/L for women). The distribution of Lp(a) was remarkably skewed (mean 190 mg/L vs median 86 mg/L for men, and 169 mg/L vs 85 mg/L for women). The 95% intervals for apo A-I were 1.09-1.84 g/L for men and 1.06-2.28 g/L for women; for apo B, they were 0.63-1.88 g/L and 0.56-1.82 g/L, respectively. Apo A-I concentrations appeared to be unrelated to age, whereas apo B and Lp(a) concentrations were age-dependent. Cutoff values based on the 90th percentile for apo B and the 10th percentile for apo A-I are proposed for identifying subjects at increased risk of coronary heart disease.
Detection of prostate-specific antigen mRNA by reverse transcription polymerase chain reaction and time-resolved fluorometry
Authors: Galvan B , Christopoulos T K , Diamandis E P 
Published: January 2020

Abstract
We have developed a time-resolved fluorometric hybridization assay for detecting prostate-specific antigen (PSA) mRNA amplified by reverse transcription polymerase chain reaction. During PCR, digoxigenin-11-dUTP is incorporated into the amplified product. An oligonucleotide internal to the primers is used as a specific probe, being biotinylated and captured on streptavidin-coated microtiter wells. Denatured PCR product hybridizes with the probe, and the hybrids are detected with an alkaline phosphatase-labeled antidigoxigenin antibody. We used the phosphate ester of fluorosalicylic acid as the substrate. The fluorosalicylate produced forms a highly fluorescent ternary complex with Tb(3+)-EDTA, which we can measure by time-resolved fluorometry. A signal-to-background ratio of 10 was obtained when 160 PSA cDNA molecules were present in the preamplification sample. Also, mRNA corresponding to one LNCaP cell in the presence of 10(6) PSA-negative cells can be detected (signal-to-background ratio of 3.1). Samples containing 100, 1000, and 50,000 LNCaP cells gave CVs of 12.4%, 4.9%, and 6.8%, respectively (n = 10).
Quantitative determination of high-, low-, and very-low-density lipoproteins and lipoprotein(a) by agarose gel electrophoresis and enzymatic cholesterol staining
Authors: Nauck M , Winkler K , März W , Wieland H 
Published: January 2020

Abstract
Quantification of lipoprotein cholesterol was performed by enzymatic staining of cholesterol in a new agarose gel electrophoresis method that allows the separation of LDL, VLDL, HDL, and lipoprotein(a) [Lp(a)]. Lp(a) shows an electrophoretic mobility clearly distinct from VLDL and HDL. The total CVs of lipoprotein cholesterol varied between 2.7% and 3.9% for LDL, 7.8% and 23.2% for VLDL, 5.2% and 9.5% for HDL, and 6.8% and 16.4% for Lp(a). Comparison of LDL-, VLDL-, and HDL-cholesterol concentrations with the results of a combined ultracentrifugation and precipitation technique gave correlation coefficients of 0.961, 0.947, and 0.918, respectively; comparison of Lp(a)-cholesterol values with those of a nephelometric Lp(a) assay gave r = 0.906. The new electrophoretic assay has several advantages: It allows the quantification of Lp(a)-cholesterol; VLDL-cholesterol is not affected by Lp(a)-cholesterol; and the LDL-cholesterol fraction does not contain Lp(a)-cholesterol, as happens with LDL-cholesterol determined by ultracentrifugation and precipitation.