bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic Study of Apo B100 Containing Lipoprotein Metabolism Using Amino Acids Labeled with Stable Isotopes: Methodological Aspects
Authors: Maugeais Cyrille , Ouguerram Khadija , Krempf Michel , Magot Thierry
Published: October 2004

Kinetic disturbances of lipoprotein metabolism are important to know for a better understanding of lipid diseases or effects of drugs. These kinetic aspects were previously studied with radioactive tracers. The ethical concerns related to these tracers can be now overcome at a reasonable cost with the new development of small bench top mass spectrometers and the increased production of stable isotope tracers. In this review, we will discuss some methodological aspects related to stable isotope tracers and the analysis of the data with non-compartmental or compartmental models.
Activated Immune System in Patients with Huntington's Disease
Authors: Leblhuber Friedrich , Walli Johannes , Jellinger Kurt , Tilz Gernot P , Widner Bernhard , Laccone Franco , Fuchs Dietmar
Published: October 2004

Abnormalities of immune system compartments were determined in 12 patients with Huntington's disease (eight males, four females; age 42.4 ± 11.7 years) and 11 controls (7 males, 4 females; age 47.0 ± 12.0). All patients were free from infectious diseases. Serum concentrations of a panel of serum soluble markers of immune activation were investigated, namely neopterin, 55-kDa-type soluble tumor necrosis factor receptor (sTNF-R), interleukin-2-receptor (sIL-2R), kynurenine, tryptophan, immunoglobulins (Ig) A, M and G as well as routine laboratory tests. Compared to controls, we found significantly higher serum levels of IgA (p < 0.01), sTNF-R, sIL-2R, neopterin, and complement component C3 (all p < 0.05), and serum tryptophan was decreased (p < 0.001). Higher concentrations of circulating immune complexes, cardiolipin antibodies, IgM, neopterin and lower tryptophan were associated with loss of cognitive function as assessed by the minimental-test. Five patients died within 1 year after measurements were performed. In these patients IgM, circulating immune complexes and neopterin concentrations were higher compared to survivors and serum tryptophan was lower. The data indicate an activation of various immune system compartments in Huntington's disease and that systemic immunological alterations might be important in the course of the disease.
Elevated Group 11 Phospholipase A2 Mass Concentration in Serum and Colonic Mucosa in Crohn's Disease
Authors: Haapamäki Markku M. , Grönroos Juha M , Nurmi Heimo , Söderlund Kristiina , Peuravuori Heikki , Alanen Kalle , Nevalainen Timo J.
Published: October 2004

Group II phospholipase A2 has been proposed to play an important role in the pathophysiology of inflammatory bowel diseases. This enzyme has also been linked to host defence mechanisms against bacteria. The current study aimed at measuring the mass concentrations of group II phospholipase A2 in serum and colonic mucosa of patients with Crohn's disease of different severity and of appropriate control patients without any inflammatory disease. The activity of the disease was determined by clinical factors (the simple index score) and endoscopic and histological scoring. The mass concentration of group II phospholipase A2 was measured by a time-resolved fluoroimmunoassay. The mass concentrations of group II phospholipase A2 in serum and colonic mucosa were significantly higher both in patients with active and inactive Crohn's disease when compared with controls. There was statistically significant difference in the mass concentration of group II phospholipase A2 in colonic mucosa but not in serum between inactive and active Crohn's disease. The current results indicate that the mass concentration of group II phospholipase A2 is increased in serum and colonic mucosa of patients with Crohn's disease and that the latter is associated with the degree of the inflammatory activity in the intestinal wall. These results support the idea that group II phospholipase A2 is involved in the local and generalised pathological processes of Crohn's disease.
Determination of pH in Human Erythrocytes. Sources of Systematic Error
Authors: Büttner Dietlinde , Büttner Johannes
Published: October 2004

The results of a simultaneous determination of the pH value in erythrocytes with the potentiometric measuring method and the 14C-labelled 5,5-dimethyl-2,4-oxazolidinedione (DMO) method showed a mean method difference of 0.026 pH units. The cause of this discrepancy was assumed to be matrix-inherent liquid-junction potentials in the potentiometric measurement. Taking these into account in the calculation leads to consistent values for the methods investigated. The DMO method proved to be free of systematic errors. Another indication of this is that its mean ratio of extracellular to intracellular H+ ion concentration (He
+/Hi
+) substantially agreed with the distribution ratios of other freely diffusible ions and their pH dependence.
Rapid Molecular Diagnosis of Erythropoietic Protoporphyria among Swiss Patients
Authors: Rüfenacht Urszula B. , Schneider-Yin Xiaoye , Schäfer Beat W. , Taketani Shigeru , Deybach Jean-Charles P. , Minder Elisabeth I.
Published: October 2004

Erythropoietic protoporphyria (EPP) is an autosomal dominant inherited disorder with incomplete penetrance. It is caused by partial deficiency of ferrochelatase, the last enzyme in the heme biosynthetic pathway. Measurement of protoporphyrin concentrations in red cells and feces, although sufficient for diagnosis of symptomatic EPP patients, fails to detect asymptomatic gene carriers. We have developed a molecular diagnostic procedure for rapid and reliable screening of five known mutations in the ferrochelatase gene among Swiss EPP patients in a single denaturing gradient gel electrophoresis (DGGE) gel.
Biochemical Evaluation of Oxidative Stress in Propylthiouracil Treated Hyperthyroid Patients. Effects of Vitamin C Supplementation
Authors: Seven Arzu , Taşan Ertuǧrul , İnci Figen , Hatemi Hüsrev , Burçak Gülden
Published: October 2004

In this study the impact of vitamin C supplementation on oxidative damage as assessed by thiobarbituric acid reactive substances and markers of antioxidant status: namely Cu/Zn superoxide dismutase, glutathione peroxidase, glutathione reductase and glutathione were investigated in 24 hyperthyroid patients under propylthiouracil therapy (3×100 mg/day) for five days and in 15 healthy controls. Ascorbic acid (1000 mg/day) was given as a supplement for 1 month to both the patients and controls during the study period. Heparinised blood samples were taken at the beginning and the end of one month ascorbic acid supplementation.

Comparison of the hyperthyroid patients with the controls revealed higher lipid peroxidation (p<0.001), higher Cu/Zn superoxide dismutase activity (p<0.001), higher glutathione level (p<0.001) and lower glutathione reductase activity (p<0.001).

Vitamin C supplementation to hyperthyroid patients caused significant increases in glutathione concentration (p<0.001) and glutathione peroxidase activity (p<0.001), whereas there were significant decreases in glutathione reductase (p<0.001) and Cu/Zn superoxide dismutase activities (p<0.01). Thiobarbituric acid reactive substances and thiobarbituric acid reactive substances/glutathione ratio were significantly decreased (p<0.01).

Vitamin C supplementation to euthyroid controls caused significant increases in glutathione concentration (p<0.001) and glutathione peroxidase and Cu/Zn superoxide dismutase activities (p<0.001), whereas there was a significant decrease in glutathione reductase (p<0.001). The thiobarbituric acid reactive substances/glutathione ratio was significantly decreased (p<0.05).

Our findings reveal the potentiation of antioxidant status and a relief in oxidative stress in both propylthiouracil treated hyperthyroid patients and controls in response to vitamin C supplementation.
Effect of Aminoguanidine on Erythrocyte Lipid Peroxiclation and Activities of Antioxidant Enzymes in Experimental Diabetes
Authors: Kȩdziora-Kornatowska Kornelia Z. , Luciak Marek , Błaszczyk Jan , Pawlak Wojciech
Published: October 2004

The effect of aminoguanidine (AG) on the malondialdehyde (MDA) concentration and activities of superoxide dismutase (SOD), catalase and glutathione peroxidase (GSH-Px) in erythrocytes of rats with streptozotocin-induced diabetes was studied. Induction of diabetes resulted in an increase of MDA concentration and decreases of SOD and catalase activities after 6 and 12 weeks. GSH-Px activity increased after 6 weeks and returned to control values after 12 weeks. AG administration did not affect body weight, blood glucose level and HbA1c content in diabetic rats but led to a decrease of MDA concentration and SOD and catalase activities after 12 weeks of treatment, with no significant effect after 6 weeks. AG attenuated the GSH-Px increase after 6 weeks but augmented the activity of this enzyme after 12 weeks. These results confirm the presence of oxidative stress in streptozotocin-induced experimental diabetes and point to the beneficial antioxidant effect of AG.
Normalizing Intermethod Free Triiodothyronine Patient Results: Need for Commutable Materials
Authors: Cattozzo Giampaolo , Scarsi Giorgio , Franzini Carlo
Published: October 2004

The aim of this work was to check the suitability of control materials to normalize intermethod results for the measurement of free triiodothyronine in patient sera. In the main experiment, 108 patient sera and 11 commercially available control materials were assayed by a pair of methods. In a confirmatory experiment, two of the control materials and 142 patient sera were assayed with an alternative pair of methods. In the main experiment, the intermethod variability of 6/11 control materials differed significantly from that of patient sera (i. e. control materials were non-commutable). Recalculation of patient results using control materials as calibrators lowered the intermethod difference only if commutable materials were used. The confirmatory experiment demonstrated that the pattern of commutability changed if a different pair of methods was used. We conclude that in the case of free triiodothyronine the commutability of control materials should be tested if they are to be used to normalize patient results obtained by different methods.
Evaluation of a Predictive Kinetic Procedure for the Enzymatic Measurement of Creatinine in Serum
Authors: Yago Martín , Olmos María José , Gómez Trinidad
Published: October 2004

We have evaluated the analytical performance of a predictive kinetic procedure for the enzymatic measurement of serum creatinine in comparison with equilibrium and kinetic fixed-time procedures. The procedure uses commercially available reagents and is based on calculating the total change in absorbance expected if the reaction were to proceed to equilibrium by fitting the initial part of the absorbance-time curve to a three-parameter function by non-linear regression. Total imprecision for different concentrations of creatinine ranges from 1.47 to 1.86% and is significantly better than that obtained for the fixed-time procedure. The results with the predictive procedure are less dependent on creatinine amidohydrolase activity in the reagent, pH of the reagent and temperature of analysis than are the results with the fixed-time procedure. All the procedures are interfered with by bilirubin and ascorbic acid to about the same extent. Recovery and linearity are quite acceptable, and the estimated accuracy is below 2.1%. However, in comparison with the equilibrium procedure, the predictive procedure tends to underestimate creatinine concentrations at values below 100 μmol/l, and the results obtained by the two procedures are not transferable. In conclusion, the predictive approach substantially improves the imprecision but not the specificity of the enzymatic assay of serum creatinine.
Pre-Evaluation and System Optimization of the Elecsys® Thyroid Electrochemiluminescence Immunoassays
Authors: Luppa Peter B. , Reutemann Stefan , Huber Ursula , Hoermann Rudolf , Poertl Stefan , Kraiss Stefan , von Bülow Sabine , Neumeier Dieter
Published: October 2004

We present the results of a pre-evaluation of the thyroid function test free thyroxine, free triiodothyronine and third generation TSH using the Elecsys® electrochemiluminescence immunoassay system. A collaborative field study between the development center of the manufacturer and a clinical chemistry laboratory addressed the reliability and comparability of the new Elecsys® assays to established methods under clinical laboratory conditions using samples from routine in vitro thyroid testing. Preliminary (reference) formulations of the reagents and several electrochemiluminescent pilot models were used for assay measurements, either in the company's research center or in the clinical setting. The new thyroid assays were compared with the respective Enzymun-Test® assays, performed on the ES 300 automated immunoassay analyzer. A WHO standard was used for standardization of TSH, whereas an equilibrium dialysis method was applied for free triiodothyronine. The free thyroxine assay was standardized against the Enzymun-Test® free thyroxine assay, which had previously been calibrated against equilibrium dialysis.

The aim of this field study was to support the optimization of the technology used for Elecsys® in an early stage of development and thereby prepare the ground for the adaptation of the immunoassays to the final Elecsys® 2010 random access analyzer. A subsequent multicenter evaluation demonstrated that the requirements of routine thyroid testing in terms of reliability were fulfilled by the system.
Validation of an Automated Enzyme Immunoassay for Interleukin-6 for Routine Clinical Use
Authors: Fraunberger Peter , Pfeiffer Matthias , Cremer Peter , Holler Ernst , Nagel Dorothea , Dehart Isabelle , Thein Michael , Walli Autar K. , Seidel Dietrich
Published: October 2004

Serum levels of Interleukin-6 (IL-6), a proinflammatory cytokine, are increased in early stages of inflammatory diseases such as infection and sepsis. Assay systems which permit its measurement within a few hours and as a single measurement have not been reported so far. We therefore evaluated a now commercially available automated method for IL-6 measurement on the Cobas Core®immunological analyzer (Roche Diagnostic Systems) which enables single IL-6 measurement within about 1 hour. The automated assay correlates well with an established, manual microtiter plate assay (Biosource GmbH) which uses the same antibodies and reagents (r=0.98). Accuracy of the automated method was established by adding known amounts of IL-6 international reference preparation. Recovery of the international standard was in the range of 92–104 %. The automated assay had a precision of singletons below 6% and was linear up to 2800 pg/ml. This automated assay provides a suitable, convenient and time saving method for measurement of IL-6 serum levels in the routine clinical laboratory.
First Experience with the REMEDi HS Urine Benzodiazepine Assay
Authors: Musshoff Frank , Madea Burkhard
Published: October 2004

Ninety eight urine samples were analysed with an immunoassay benzodiazepine kit. A total of 68 urine specimens that were presumptively positive for benzodiazepines were evaluated by the REMEDi HS urine benzodiazepine assay (BIO-RAD, Munich, Germany). Of this number, 53 (78 %) specimens were found by REMEDi to contain one or more benzodiazepines or their metabolites, and 15 (22 %) were found to be negative. From the discordant group of 15 samples, eight were found to be negative using conventional chromatographic procedures (HPLC or GC/MS), while seven contained one or more benzodiazepines or metabolites, each of which were below the individual cut-off level specified by the manufacturer. Additionally 30 urine specimens that were negative for benzodiazepines using immunoassay were also tested by REMEDi. Two samples were found to be positive. These results could not be confirmed by other chromatographic techniques.

The REMEDi HS benzodiazepine assay can be a very useful complementary technique in the clinical/forensic toxicology laboratory, especially for the identification of the parent benzodiazepines administered. The assay provides a rapid result in emergency situations and is useful in confirmation of preliminary positive immunoassay results.
Expert Systems for the Interpretation of Serum Proteins
Authors: Ritchie Robert F.
Published: October 2004

The ready availability of inexpensive desk-top computers
with enormous disk storage has made the practicality of computer assisted
medical interpretive software a reality. There seems little question that these
programs could be of enormous help to physicians. However, there are daunting
problems to their creation, including the lack of standards for clinical
diagnostic precision or accuracy and paucity of helpful literature. As a result,
the final products may be quite different. Little effort has been devoted in the
laboratory to produce programs which could have great benefit in bridging the
gap between laboratorians and clinicians. In a few circumscribed areas where the
interpretation of laboratory measurements have been well studied in relation to
patient demographics and to the final outcome, the impact has been enormous. The
prime example is prenatal diagnosis of neural tube defects, and certain
chromosomal and developmental abnormalities. Viewed as an obstacle by most
people able and willing to attempt to create such programs is the omnipresence
of necessary regulation. A brief overview of the general structure of a program
to assist with the interpretation of serum proteins is given as a model in the
perspective of current knowledge and state of the relevant literature.
Proteome in Perspective
Authors: Hochstrasser Denis F.
Published: October 2004

This review describes briefly proteome science. It explains why proteome science or proteomics emerged only recently and why a shift from genomics to proteomics is occurring. This review further illustrates that proteomics can unravel new domains in nature's complexity. Finally, it demonstrates that proteomics is offering new tools for the study of complex biological or medical problems.
Usefulness of Chromogranin A as a Marker for Detection of Relapses of Carcinoid Tumours
Authors: Pirker Robert A. , Pont Jörg , Pöhnl Rainer , Schütz Wolfgang , Griesmacher Andrea , Müller Matthias M.
Published: October 2004

It is well known that peptide-producing endocrine
tumours cosecrete immunoreactive chromogranin A with their characteristic
hormones. Into this study 187 patients with the diagnosis malignant carcinoids
or other malignancies were entered. Using chromogranin A at a cut-off level of
30.3 U/ml it was possible to discriminate between patients in remission and
patients suffering a relapse with a sensitivity of 91.7% and a specificity of
96.4 %, which may be of important diagnostic value. In our study that lasted
over one year we could clearly show that the measurement of chromogranin A is
impressively superior to 5-hydroxyindoleacetic-acid for detecting a relapse of
carcinoids.
Comparison of Tissue Polypeptide Antigen (TPA) with Cancer Antigen 15-3 (CA 15-3) and Carcino-embryonic Antigen (CEA) in Follow-up of Breast Cancer
Authors: Findeisen Rainer , Albrecht Steffen , Richter Barbara , Deutschmann Kersten , Distler Wolfgang
Published: October 2004

Cancer antigen 15–3 (CA 15–3), carcinoembryonic antigen
(CEA) and tissue polypeptide antigen (TPA) were measured in 679 sera of breast
cancer patients and in 94 sera of women without breast cancer. The tumour
markers were determined using immunoluminometric assays (ILMA). The assays are
characterised by an inter-assay-imprecision and intra-assay-imprecision <4 %.
The breast cancer patients were staged according to the TNM classification stage
0–IV (by UICC) in patient groups with a compatible prognosis. Median and range
of each stage were investigated. The cut-off values (95th and 97.5th percentile
of control group) of CA 15–3, CEA and TPA were determined; specificity,
sensitivity, positive and negative predictive value (PV) and efficiency were
investigated for these cut-off's and the receiver operating characteristic (ROC)
curves were calculated. The differences between control group and stage 0–3 were
shown as non-significant for CA 15–3 and CEA but significant for TPA.
Significant differences were found in stage 4 for all three tumour markers. The
three tumour markers did not have differences in specificity, positive and
negative PV and efficiency. TPA and CA 15–3 demonstrated comparable results in
sensitivity and ROC curve analyses. These results were better than those from
CEA.
Continuous Analysis in Extracorporeally Circulating Blood - A Rat Model Applying Flow-Through Ion-Selective Electrodes for the Measurement of Ca2+, K+, Na+ and pH
Authors: Heidrich Jens P. , Niemeier Anja , Seyfarth Michael
Published: October 2004

A rat model is introduced which enables investigations
in anticoagulated blood with continuous measurements by a flow-through electrode
system. In the present study, a potentiometric ion-selective electrode
(ISE)-system was used for measuring Ca2+, K+,
Na+ and pH in rats. The setup was adjusted to an extracorporeal
blood-volume of 0.750 ml. This permits indirect measurements of the analytes via
a dialysis membrane, with electrical separation of the ISE's and the animal. The
flow-rates of blood and dialysis-solution were adjusted in such a way that water
diffusing from the aqueous dialysis solution into the blood, across the dialysis
membrane, does not alter the haematocrit. Polyethyleneglycol-hirudin was used
for anticoagulation, since it was superior to heparin. The assembly enables
continuous measurements in the living anaesthetized rat over a time period of at
least 3 hours.
Improved Specificity of a New Direct Assay for Urinary Cortisol: Application in Corticoid Treated Patients
Authors: Sapin Rémy , Schlienger Jean Louis , Gasser Françoise , Pradignac Alain , Grucker Daniel
Published: October 2004

Twenty four hours urinary free cortisol (UFC) excretion
has been determined in 35 eucortisolic control patients, in seven of them before
and after tetracosactide (Synacthen®) stimulation and in 18 patients treated by
anti-inflammatory steroids. Results of the new direct Immunotech RIA (DIm) were
compared to those of the INCSTAR RIA kit with (ECA) or without methylene
chloride extraction (DCA). In controls DIm UFC (106.2±45.8 nmol/24h) was
significantly lower than DCA UFC (397±119 nmol/24h) and than ECA UFC (127±49
nmol/24h). After tetracosactide stimulation, median of DCA/DIm ratio decreased
from 3.61 to 1.88 whereas ECA/DIm ratio did not change significantly (1.31 to
1.06). In treated patients most DCA and ECA results were over the upper limit of
controls but only 5 DIm results were increased. DIm assay showed good
specificity and practicability and may be used with benefit in the evaluation of
the adrenal gland function.
Quantitative Automated Particle-Enhanced Immunonephelometric Assay for the Routinary Measurement of Human Cystatin C
Authors: Mussap Michele , Ruzzante Nicoletta , Varagnolo Mariacristina , Plebani Mario
Published: October 2004

Human cystatin C is a low molecular mass protein of
13359 Dalton recently proposed as a new very sensitive marker of changes in
glomerular filtration rate. Serum cystatin C concentration correlates negatively
with glomerular filtration rate as well as or better than creatinine. We
evaluated a recently introduced automated nephelometric immunoassay for cystatin
C in serum or EDTA-plasma samples on the Behring Nephelometer System. The assay
consists of incubating the 100-fold diluted sample for 6 minutes with latex
particles covalently coated with anti-human cystatin C antibodies, and then
quantifying the change of light-scatter produced. Method reproducibility is
satisfactory, the intra-and inter-assay coefficients of variation ranging from
1.58 % to 3.77 % and from 5.6 % to 11.47 % respectively. Rheumatoid factor (≤
1116 IU/ml), bilirubin (≤ 418 μmmol/l), triglycerides (10.47 mmol/l), and
haemoglobin (12 g/l) do not significantly interfere in the assay. No significant
difference was found in cystatin C concentration between serum and EDTA-plasma
samples. Cystatin C is stable in serum samples stored under different conditions
up to one month. This method correlates well (mean difference = −0.536 ± 0.307
mg/l) with another commercially available particle-enhanced turbidimetric
immunoassay. Cystatin C offers better clinical sensitivity than creatinine for
discriminating patients with normal renal function and those with
mild-to-moderate reduction in renal function. This method is suitable for
routine cystatin C measurement, including emergencies.
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

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

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

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

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

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

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

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

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

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

The 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

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

Troponin 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

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

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.