bluuebunny/crossref_metadata_2025_split huggingface dataset:
External Quality Assessment of Stat Test Intralaboratory Turnaround Times. Pilot Study from the Members of the Working Group for the Standardization and Promotion of Turnaround Time Control under the Auspices of the Comitato Italiano per la Standardizzazione die Metodi Ematologici e di Laboratorio
Authors: Negri Mauro , Carraro Paolo , Caenaro Gianfranco , Cappelletti Piero , Giavarina Davide , Mezzena Gabriella , Prandini Benigno , Rampoldi Erica , Siviero Fosca 
Published: October 2004

Abstract
We describe procedures, results and prospects of a pilot
program in External Quality Assessment (EQA) of the stat test intralaboratory
turnaround times. Our goals are to promote quality by systematic monitoring and
comparison of performances by laboratories, continuous investigation into the
state of the art of the processes from receipt of sample to transmission of
results and creation of a data base for standardization of measures and
definition of consensus values for turnaround time.
Of 30 laboratories invited to participate, 25 took part,
agreeing to record times of arrival and transmission for all determinations of
three analytes (blood hemoglobin, serum/plasma potassium and plasma prothrombin
time) for seven consecutive days and to continue for one or more further periods
of seven days as necessary if there were less than 300 determinations for each
analyte. Within a preset time limit, data were sent by e-mail on an Excel™ file
and we sent back two reports per analyte, showing: i) the graph for time vs.
percentage of tests completed and several measures of turnaround time; ii)
results of all laboratories in graph form, allowing each laboratory to identify
only its own data.
The high proportion of participating laboratories among
those invited (83 %) encourages us to implement the EQA program systematically,
on a half-yearly basis, extending it to all laboratories wishing to participate
in Italy or elsewhere in Europe.
Biological Effects of Eleven Combined Oral Contraceptives on Serum Triglycerides, γ-Glutamyltransferase, Alkaline Phosphatase, Bilirubin and other Biochemical Variables
Authors: Schiele Françoise , Vincent-Viry Monique , Fournier Blandine , Starck Marjorie , Siest Gérard 
Published: October 2004

Abstract
The objectives of this paper are to update and quantify
the biological effects of the most commonly used oral contraceptives (OC) on 15
biochemical tests currently determined in clinical laboratories and to compare
these effects between the different types of OC. The sample population was
constituted by 1604 women using combined OCs and the control group comprised
3466 women in the same age range not taking medication. Women taking OC were
divided into 11 groups according to the estrogen/progestogen combination. The
effects of OCs were studied after adjustment for age, weight, height, body mass
index and alcohol and tobacco consumption. The changes observed with the new
progestogens were less important than in the past. In comparison with the
controls, the mean serum triglyceride concentration was significantly increased
by ＋8.5 % to ＋36.0 % (p<0.05 to p<0.001) in each group while those of
total cholesterol and γ-glutamyltransferase were increased only in 3 and 4
estrogen/progestogen combinations respectively. Conversely, the mean
concentrations of alkaline phosphatase, total bilirubin, phosphate and albumin
were significantly decreased. Using a discriminant analysis, three main groups
according to the type of progestogen were defined: cyproterone acetate,
DL-norgestrel and levonorgestrel, and all other progestogens. The changes in
serum triglyceride concentration induced by OC intake must be considered by the
clinician and are useful for taking a clinical and risk decision in an
individual woman.
Diagnostic and Prognostic Value of Biochemical Markers in Malignant Bone Disease: A Prospective Study on the Effect of Bisphosphonate on Pain Intensity and Progression of Malignant Bone Disease
Authors: Engler Hanna , Koeberle Dieter , Thuerlimann Beat , Senn Hans-Jörg , Riesen Walter F. 
Published: October 2004

Abstract
Seventy cancer patients with malignant osteolytic bone
disease received pamidronate every three weeks for a maximum of six cycles. Bone
resorption parameters, urinary calcium excretion, and pain parameters were
assessed at baseline and throughout the study. At baseline, 80–95 % of patients
showed elevated urinary pyridinoline, deoxypyridinoline, Osteomark® NTx and
serum ICTP® levels, whereas only 35 % of patients had elevated urinary
CrossLaps® excretion rates. During bisphosphonate therapy, significant decreases
in Osteomark® NTx, CrossLaps® and calcium excretion were observed, which were
not related to the clinical outcome. The baseline levels of bone resorption
markers were used to predict the probability of non-progressive bone disease or
reduction in pain intensity during bisphosphonate therapy. Significant
predictors of non-progressive bone disease were urinary pyridinoline and serum
ICTP levels; significant predictors of reduction in pain intensity were urinary
free deoxypyridinoline and serum ICTP levels.
Our data indicate that serum ICTP levels predict
significantly the response to bisphosphonate therapy in patients with advanced
malignant osteolytic bone disease. CrossLaps did not predict the clinical
outcome, but decreased significantly during bisphosphonate therapy. Our data
demonstrate that the different bone resorption markers are reflecting different
aspects of bone metabolism, and therefore differ in their diagnostic and
prognostic properties.
IFCC Committee on Standardization of Markers of Cardiac Damage: Premises and Project Presentation
Authors: Panteghini Mauro 
Published: October 2004

Abstract
The field of biochemical markers of cardiac damage is in
a dynamic state, with new applications continually appearing and new assays and
markers being developed. These significant and sudden advancements in the
development of new biochemical assays have led however to several analytical and
interpretative problems. In this situation, it is essential that a uniform and
rigorous outlook be maintained to ensure optimal test utilization. For these
reasons, the IFCC Scientific Division recently agreed to establish a Committee
on "Standardization of Markers of Cardiac Damage" (C-SMCD), inviting members
from the established American and European groups to become members of this
Committee. In this presentation, the premises, the issues, and the proposed plan
of action of C-SMCD are presented and discussed.
Six Methods for the Determination of C-Peptide Evaluated
Authors: Nauck Markus S. , Nauck Matthias A. , Nauck Michael A. , März Winfried , Wieland Heinrich 
Published: October 2004

Abstract
Six assays for C-peptide were evaluated. Five assays were radioimmunoassays; one was a chemiluminescence assay. The within-run coefficient of variation ranged between 2.1 and 22.9 %. The methods correlated well with each other (r = 0.925 to 0.978). There were, however, proportional biases between the assays, in particular in the higher concentration range. All assays were linear up to at least 4.5 ng/ml C-peptide concentration. All assays were easy to perform. However, the systematic bias between the assays demonstrates that further effort is needed to standardize the measurement of C-peptide. In the meantime, we recommend that laboratories conducting C-peptide measurements establish local, method-specific reference ranges.
Urinary Porphyrin Excretion in Hepatitis C Infection
Authors: Vogeser Michael , Jacob Karl , Zachoval Reinhart 
Published: October 2004

Abstract
A high prevalence of hepatitis C virus infection in porphyria cutanea tarda in some populations suggests a close link between viral hepatitis and alteration of porphyrin metabolism. Moreover, there is evidence of a role of porphyrinopathies in hepatocarcinogenesis. The aim of our study was to obtain data on the prevalence and patterns of heme metabolism alterations in patients with chronic hepatitis C virus infection. Urinary porphyrin excretion was prospectively studied in 100 consecutive outpatients with chronic hepatitis C infection without signs of photosensitivity, using an ion-pair high-performance liquid chromatography method. Increased total porphyrin excretion was found in 41 patients, with predominant excretion of coproporphyrins (whole study group: mean 146 μg/g creatinine, interquartile range 76–186; normal < 150), in 10 patients excretion exceeded 300 μg/g creatinine. In the majority of all patients studied (75/100) an increased ratio of the relatively hydrophobic coproporphyrin isomer I to isomer III was found. In just one case, urinary porphyrin pattern characteristic for chronic hepatic porphyria was present (uroporphyrin > coproporphyrin, heptacarboxyporphyrin III increased) but the total porphyrin excretion was only slightly elevated in this case. In the whole group, total urinary porphyrin excretion correlated well with serum bilirubin and was inversely correlated with albumin and thrombin time. In conclusion, secondary coproporphyrinuria occurs frequently in heptatitis C infection, whereas in Germany, preclinical porphyria cutanea tarda seems to be rare in these patients.
Quantification of Low Abundance Natriuretic Peptide Receptor mRNA in Rat Tissues
Authors: Höhnel Klaus , Dietz Rainer , Willenbrock Roland 
Published: October 2004

Abstract
Natriuretic peptides are important regulators of vascular resistance and volume and electrolyte homeostasis. The quantification of natriuretic peptide receptor (NPR) mRNA is important for the understanding of the regulation of this humoral system, but is difficult due to low expression of the NPR mRNA. We report here on the evaluation of a polymerase chain reaction (PCR)-aided transcript titration assay for quantification of all three NPR subtypes (NPR-A, NPR-B, and NPR-C) mRNA. A multispecific internal standard RNA with parts of NPRA, NPR-B, NPR-C and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) nucleotide sequences was constructed and reverse transcription of standard and sample RNA (400 ng) was performed in parallel for all three NPRs and GAPDH. The specific PCR yielded differently sized products, which were quantified by high performance liquid chromatography (HPLC). The determination of specific mRNA concentrations was not influenced by cDNA input and did not depend on the PCR cycle number. Linearity between sample RNA input and mRNA concentration was demonstrated. Application of the evaluated method showed that the NPR-A mRNA expression was the most abundant of the three natriuretic peptide receptor mRNAs in rat lungs, glomeruli and left ventricles, followed by the NPR-C mRNA and the NPR-B mRNA expression. Thus, the described method allows the reliable quantification of the specific mRNA expression of all three NPRs with small amounts of RNA. The presented method might foster future research on the regulation of this humoral system in cardiovascular and kidney diseases.
Artificial Neural Networks in Laboratory Medicine and Medical Outcome Prediction
Authors: Tafeit Erwin , Reibnegger Gilbert 
Published: October 2004

Abstract
Since the early nineties the number of scientific papers reporting on artificial neural network (ANN) applications in medicine has been quickly increasing. In the present paper, we describe in some detail the architecture of network types used most frequently in ANN applications in the broad field of laboratory medicine and clinical chemistry, present a technique-structured review about the recent ANN applications in the field, and give information about the improvements of available ANN software packages.
ANN applications are divided into two main classes: supervised and unsupervised methods. Most of the described supervised applications belong to the fields of medical diagnosis (n=7) and outcome prediction (n=9). Laboratory and clinical data are presented to multilayer feed-forward ANNs which are trained by the back propagation algorithm. Results are often better than those of traditional techniques such as linear discriminant analysis, classification and regression trees (CART), Cox regression analysis, logistic regression, clinical judgement or expert systems. Unsupervised ANN applications provide the ability of reducing the dimensionality of a dataset. Low-dimensional plots can be generated and visually understood and compared. Results are very similar to that of cluster analysis and factor analysis. The ability of Kohonen's self-organizing maps to generate 2D maps of molecule surface properties was successfully applied in drug design.
A New Liquid Homogeneous Assay for HDL Cholesterol Determination Evaluated in Seven Laboratories in Europe and the United States
Authors: Nauck M. , Graziani M. S. , Jarausch J. , Bruton D. , Cobbaert C. , Cole T. G. , Colella F. , Lefevre F. , Gillery P. , Haas B. , Law T. , König M. , Macke M. , März W. , Meier C. , Riesen W. , van Vliet M. , Wieland H. , Rifai N. 
Published: October 2004

Abstract
We evaluated a new liquid homogeneous assay for the direct measurement of high density lipoprotein cholesterol (HDL-C Plus) in seven laboratories. The assay includes two reagents which can be readily used in most available clinical chemistry analyzers.
The total CVs of the new method were below 4.6% and the bias in relation to the designated comparison method was below 3.9%. The total error ranged between 4 to 7%. HDL-C values determined by this method were in good agreement with those obtained by the old homogeneous assay using lyophilized reagents, and other homogeneous and precipitation assays (0.944 < r < 0.996). The assay was linear up to at least 3.89 mmol/l HDL-C.
Hemoglobin did not interfere, whereas in icteric samples slight deviations were observed. Lipemia up to 11.3 to 22.6 mmol/l triglycerides did not interfere with this homogeneous HDL-C assay. In samples of patients with paraproteinemia, discrepant results were seen. This liquid homogeneous HDL-C assay was easy to handle and produced similar results in all laboratories participating in this study. This method will enable clinical laboratories to reliably measure HDL-C for risk assessment of coronary heart disease.
Tissue Release of Cardiac Markers: from Physiology to Clinical Applications
Authors: Mair Johannes 
Published: October 2004

AbstractThe early release of cardiac markers is influenced by a variety of factors, the most important influence being their intracellular compartmentation. In contrast to the release of cytosolic proteins, the release of structurally bound proteins requires both a leaky plasma membrane and a dissociation or degradation of the subcellular structure, which is a slower process. Another major impact is the susceptibility to the degradation by cytosolic proteases, such as the calpains. The lysosomes are stable within the first 3–4 hours after onset of ischemia, and, therefore, their enzymes are not involved in the early degradation of structurally bound proteins. Troponin I and troponin T are substrates of μ-calpain. Current experimental as well as clinical results suggest that the molecular mass seems to be of minor importance for the pattern of appearance of myocardial proteins in blood after myocardial infarction. However, within the family of molecules with a certain intracellular compartmentation, the molecular mass is an influence on the appearance in blood, because heavier molecules diffuse at a slower rate, and particularly smaller molecules, such as myoglobin, may enter the vascular system to an even larger extent directlyviathe microvascular endothelium. The higher the concentration gradient of a marker between the cardiomyocytes and the interstitial space, the faster a parameter will translocate from sarcoplasma to the interstitial space as soon as the plasma membrane permeability is increased. Another influence is local blood and lymphatic flow. Recent experimental studies showed that reperfusion causes a true acceleration of cellular protein leakage by an acute manifestation of plasmalemmal disruptions and not just an enhanced wash out. Marker protein time-courses after myocardial damage are also markedly influenced by their disappearance rate from blood. Most proteins appear to be catabolized in organs with a high metabolic rate, such as liver, pancreas, kidneys, and the reticuloendothelial system. Smaller molecules, such as myoglobin, also pass the glomerular membranes of the kidneys and are reabsorbed and subsequently metabolized in tubular epithelial cells.
The Specificity of Biochemical Markers of Cardiac Damage: a Problem Solved
Authors: Apple Fred S. 
Published: October 2004

Abstract
This paper reviews the tissue specificity of cardiac troponin I (cTnI), cardiac troponin T (cTnT) and creatine kinase (CK) MB in human and animal heart and skeletal muscles. Studies reveal that CK-MB can be expressed up to 20% of total CK activity in human skeletal muscle; and therefore is not 100% specific for the heart. One cTnI isoform has been described and shown to be 100% specific for the heart. While one to four cTnT isoforms are expressed in diseased and regenerating human skeletal muscle, these isoforms are not the same as the cTnT isoforms expressed in the human heart and are not detected by the cTnT diagnostic assays used in clinical practice. Representative cases are described demonstrating the role of monitoring cardiac troponins in blood for differentiating false positive CK-MB increases due to skeletal muscle injury. Further, sufficient reactivity and tissue specificity of cTnI and cTnT assays are demonstrated for use as markers of myocardial injury in laboratory animals. Monitoring cTnI and cTnT concentrations in the circulation appears poised as the new standards for detection of myocardial injury.
Biochemical Factors Influencing Measurement of Cardiac Troponin I in Serum
Authors: Katrukha A. , Bereznikova A. , Filatov V. , Esakova T. 
Published: October 2004

AbstractTroponin I (cTnI), a sensitive and reliable marker of damaged cardiac tissue, is now widely used in clinics. But the existence of different cTnI assays with a wide variety of cut-off values and discrepancies between the results of measurements of one and the same sample by different assays is puzzling for clinicians. The most urgent issue at the moment is the development of the international standard, which can be used for the calibration of different assays, thus decreasing between assay biases. But another important item, which should be considered by manufacturers, is the standardisation of the epitopes of the antibodies used for the assay development. The importance of such standardisation originates from the complicated biochemical nature of cTnI. Here we briefly try to analyse the main factors that can influence antigen recognition by different antibodies and formulate principles of antibody selection for assay development.
The Sensitivity of Cardiac Markers: an Evidence-based Approach
Authors: Panteghini Mauro , Pagani Franca , Bonetti Graziella 
Published: October 2004

Abstract
The aim of this study was to determine whether, using an evidence-based approach, the results of the papers found in the literature are valid and sufficiently scientifically rigorous to be used to definitely address the problem of cardiac marker sensitivity in detection of acute myocardial infarction. In particular, the diagnostic sensitivities of myoglobin, creatine kinase (CK)-MB isoenzyme, determined as mass concentration, CK-MB isoforms, and of the two cardiac troponins, troponin I and troponin T, were reviewed using a priori formulated inclusion/exclusion criteria for judging the eligibility of studies to be included in the analysis. A clear final message derived from this systematic analysis is the unacceptably poor diagnostic sensitivity of all evaluated markers at patient admission, with substantial failure rate to rule out myocardial infarction at this time. Myoglobin is at present the most sensitive of the markers studied for excluding early AMI with an optimum timing of sampling at patient presentation and approximately 4 h later. However, this marker cannot be used by itself as a proportion of patients admitted to the hospital with a late infarction could be missed. The early rate of rise of CK-MB mass and troponin T is similar. Maximum sensitivity of these two parameters is achieved by the analysis of a second sample 6 to 12 h after admission. Additional larger studies are needed to address the question which troponin shows earlier release after myocardial damage, and to clarify the role of CK-MB isoforms as a possible early marker of myocardial infarction.
Risk Stratification and Therapeutic Decision Making in Patients with Acute Coronary Syndromes the Role of Cardiac Troponin T
Authors: Hartmann F. , Giannitsis E. , Kurowski V. , Frey N. , Kampmann M. , Katus H. A. 
Published: October 2004

Abstract
Patients with chest pain represent an inhomogeneous group with greatly varying severity of coronary artery disease and cardiac risk. The proper selection of different treatment strategies in these patients requires reliable risk assessment.
Patients with definitive myocardial infarction: in patients with ST-segment elevation on ECG, a positive troponin T (cTnT) on admission identifies a group of patients having a threefold higher mortality rate than patients with a negative cTnT test. The differences in risk based on cTnT are found for patients treated with thrombolytic as well as mechanical recanalization therapy. These differences in mortality based on admission cTnT may be explained by more severe coronary artery disease, worse left ventricular function, and less efficient microvascular reperfusion in the cTnT-positive patients.
Patients with rest angina: in patients with angina at rest, a positive cTnT value on admission identifies a subgroup having a threefold higher cardiac event rate than cTnT-negative patients. The cTnT-positive patients seem to benefit from treatment with low molecular weight heparin and fibrinogen receptor antagonists, while cTnT-negative patients do not. The differences in risk and response to therapy may be due to more severe coronary artery disease, more critical coronary artery stenoses, and a higher rate of intracoronary thrombus formation in the cTnT-positive versus negative patients.
Low risk chest pain patients: in low risk chest pain patients, (i.e. no rest angina, no ECG-changes) cTnT-positive patients on admission have a twofold higher cardiac event rate than cTnT-negative patients. The proper treatment strategy for the low risk cTnT-positive patients remains to be determined.
Troponin T versus troponin I: many of the findings on cTnT also relate to troponin I. However, there is a high interassay variability of troponin I assays, which has to be taken into consideration.
Cardiac Markers: Centralized or Decentralized Testing?
Authors: Plebani M. , Zaninotto M. 
Published: October 2004

Abstract
Testing for the diagnosis of acute myocardial infarction and other diseases included in the spectrum of the “acute coronary syndrome” is rapidly changing from the traditional enzymatic assays to mass measurement of more specific and sensitive markers (cardiac troponins, CK-MB and myoglobin). Several questions have arisen since the introduction of these new markers into the clinical setting: the choice of strategies for optimizing the utilization of biochemical assays combining different (early and specific) markers, a rationale for sampling specimens and the identification of clinically useful turnaround times. In particular, for achieving the last goal, attention has been directed toward near-patient testing for cardiac markers in addition to, or as a replacement for, traditional diagnostic methodologies. While qualitative methods for measuring cardiac markers at the bedside have some limitations which compromise their clinical usefulness, new quantitative devices offer a real alternative to decentralized testing. Regulatory and quality management issues related to near-patient testing, as well as the performance of recently introduced devices for a decentralized measurement of cardiac markers are reviewed.