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June 1, 2005
Abstract
There are large differences in the use of laboratory tests between hospitals in Sweden. These differences are not only due to differences between the patients treated but also to differences in practice. Use of laboratory test seems to reflect local traditions to a large extent. These large variations in practice are not compatible with the objective of providing care on equal terms and reduce the cost-effectiveness of clinical chemistry. Recently, several intervention studies have been performed in Sweden with the aim to optimise the use of clinical chemistry tests in primary care. The results show that it is possible to reduce the cost in primary care by SEK 100 million per year while increasing the clinical usefulness. This constitutes approximately 10% of the total cost for clinical chemistry tests in primary care. It should also be possible to reduce the cost for clinical chemistry tests in secondary and tertiary care. Hospitals order more tests than primary care and the potential savings are thus greater. We have studied the ordering habits for eleven Swedish hospitals. The comparison was made in the form of ratios between related laboratory tests to reduce the effects of differences in size between the studied laboratories. The large variation between hospitals indicates that a continuous discussion between the clinicians and the laboratories could reduce the cost. We have used the figures from the comparison and calculated the potential savings for seven frequently used tests. The potential yearly saving in Sweden for these tests is approximately SEK 150 million.
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June 1, 2005
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A new analytical method has been developed and is proposed for the rapid determination of eighteen common amino acids, including tryptophan, in plasma and dried blood spots, by liquid chromatography coupled with ionspray tandem mass spectrometry. Potentially the method can include other amino acids and can be used for the diagnosis of metabolic disease. The use of the ionspray tandem mass spectrometry approach permits extremely rapid chromatographic separation of all amino acids requiring less than four minutes for the analysis of each sample, after a simple sample preparation procedure. The chromatographic separation of the analytes was achieved using a CN normal phase column and a water/acetonitrile/trifluoroacetic acid mobile phase at flow rate of 1 ml/min. The mass spectrometer was operated in multiple reaction monitoring mode, where each analyte had its own unique precursor and product ion setting. The quantitative analysis of amino acids was achieved using as internal standards just two representative isotopically labeled amino acids: D4-Ala and D5-Phe. Calibration is made externally by using aqueous solutions with the same labelled amino acids as internal standards. The high specificity of tandem mass spectrometry coupled with a fast chromatographic process is suitable for the rapid and reliable assay of metabolically significant amino acids. The liquid chromatography-tandem mass spectrometry method is more effective than other published tandem mass spectrometry methods at distinguishing isobaric amino acids like Leu, Ile and HO-Pro and certainly far more rapid than HPLC or ion-exchange chromatographic methods.
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June 1, 2005
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In cardiac transplant recipients the release of soluble cellular adhesion molecules intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-Selectin into serum is pronounced during immune activation. It is uncertain whether there is a specific pattern of release during infection or cardiac allograft rejection. In a prospective study, 30 consecutive cardiac allograft recipients were followed for a median period of 11.4 months (range 1–34). Soluble ICAM-1 (sICAM-1), soluble VCAM-1 (sVCAM-1) and soluble E-Selectin (sE-Selectin) were measured in addition to acute phase proteins (C-reactive protein, α 1 -antitrypsin), complement factors (C3, C4) and β 2 -microglobulin. The measured serum levels were correlated with the clinical status of the transplant recipient: 1) uneventful clinical status; 2) asymptomatic infection; 3) symptomatic infection and 4) rejection. Forty age-matched healthy subjects served as controls. Six days before biopsy-proven cardiac allograft rejection sICAM-1-release started to increase (p < 0.05) as compared to uneventful clinical status. The peak concentration of sICAM-1 was measured three days before rejection. On the day of rejection, serum concentrations of sICAM-1 (p < 0.001) and sVCAM-1 (p < 0.05) were increased, whereas sE-Selectin was not markedly elevated. In symptomatic infections, the serum concentrations of sICAM-1 (p < 0.001) and sVCAM-1 (p < 0.05) were elevated at the day of diagnosis and both parameters reached peak levels three days after onset of chemotherapy. In multivariate analysis soluble adhesion molecules only weakly discriminated between rejection and infection (sensitivity: 13%, specificity: 95%). Although, in combination with routine blood parameters the discriminatory power could be improved (sensitivity: 85%, specificity: 85%) the clinical utility of these markers in non-invasive monitoring is limited.
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June 1, 2005
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We have measured the activity of class I and II alcohol dehydrogenase isoenzymes in the sera of patients with liver tumours, using class-specific fluorogenic naphthaldehydes as substrates. The activity of the tested isoenzymes was unchanged in primary tumours and significantly increased (class I) in metastatic liver tumours. The total enzyme activity was also increased (3-fold) in this group of patients. The elevated activity of class I isoenzymes in secondary tumours seems to be caused by the enzyme released from primary cells originating in the other organs, but increased total enzyme activity measured with chromogenic substrates may be proof of the presence of other classes of isoenzymes. These results show that the elevated class I isoenzymes and total enzyme activity in the sera of patients with liver tumours may indicate the metastatic origin of these tumours.
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June 1, 2005
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Serum paraoxonase circulates on a subfraction of high density lipoproteins and appears to use phospholipids on both low and high density lipoprotein particles as a physiological substrate. This functional relationship could explain the reported associations between common variation in the PON1 gene—at codons 55 and 192—and phenotypes related to atherosclerosis and lipoprotein metabolism. We evaluated associations between plasma lipoproteins and PON1 L/M55, PON1 Q/R192 and PON2 A/G148 polymorphisms in samples from two Canadian aboriginal populations, namely the Oji-Cree and the Inuit. In diabetic Oji-Cree, we found that carriers of PON1 M55 had a higher mean plasma triglyceride concentration than non-carriers. In non-diabetic Oji-Cree, we found that carriers of PON1 M55 had higher mean plasma concentrations of total and low density lipoporetein cholesterol and apo B than non-carriers. In Inuit, we found that carriers of PON1 M55 had higher mean plasma concentrations of total and low density lipoprotein cholesterol than non-carriers. The other polymorphic markers were not associated with variation in any plasma lipoprotein trait. Thus, the PON1 M55 allele appeared to be associated with deleterious changes in the plasma lipoprotein profile from two independent Canadian aboriginal samples. These results suggest that common variation in PON1 codon 55 is associated with variation of intermediate traits in plasma lipoprotein metabolism in aboriginal
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June 1, 2005
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Serum levels of lipids, lipoprotein(a) Lp(a) and other apolipoproteins were determined in 47 predialysis patients, 40 hemodialysis (HD) patients, 39 chronic ambulatory peritoneal dialysis (CAPD) patients, 11 patients after kidney transplantation and 47 healthy subjects as reference group. The predialysis, HD, and CAPD patients had disturbances in the concentration of serum triglyceride (TG), high density lipoprotein (HDL)-cholesterol, apolipoprotein AI (apoAI), total apoCIII, apoCIII present in the particles without apoB (apoCIII non B), and Lp(a) and HDL-cholesterol, low density lipoprotein (LDL)-cholesterol/HDL-cholesterol, HDL-cholesterol/apoAI, apoAI/apoB, and apoAI/apoCIII ratios. Predialysis patients had significantly lower concentrations of HDL-cholesterol and total apoE levels than CAPD patients and total apoE level than HD patients. Moreover, both HD and CAPD patients had significantly increased levels of apoB containing apoE (apoB:E) and apoB containing apoCIII (apoB:CIII). The concentrations of serum TG, total cholesterol, LDL-cholesterol, apoB, Lp(a) in CAPD patients were statistically higher than in HD patients. The patients after transplantation demonstrated normalization of lipid and lipoprotein parameters and lipoprotein ratios except serum levels of TG, total apoCIII, apoCIII non B and the apoAI/apoCIII ratio. We concluded that abnormal lipid and lipoprotein concentrations in patients with uremia may be the cause of their high risk of atherosclerosis, but post-transplant patients exhibited improved levels of serum lipids, Lp(a) and other lipoprotein parameters and lipoprotein composition, which could be an index of decreased atherogenic status.
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June 1, 2005
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Several studies have provided evidence that the remnants of lipoproteins may be the atherogenic components of triglyceride-rich lipoproteins. The purpose of this study was to investigate whether the remnant-like particle cholesterol (RLP-C) is an independent risk factor for coronary artery disease (CAD) and non-insulin dependent diabetes mellitus (NIDDM) in the Korean population and to explore the relationship between RLP-C and other biochemical markers as well as the apolipoprotein (apo) E genotypes. Lipid and lipoproteins including RLP-C and apo E genotypes were analyzed in 98 normal adults (control group), 68 patients with CAD (CAD group), 88 patients with NIDDM (DM group), and 19 patients with both CAD and NDDM (CAD + DM group). RLP-C levels were significantly higher in the DM (p< 0.0001), CAD (p = 0.0012) and the CAD + DM groups (p = 0.0184) than in the controls. To determine which variable could discriminate most effectively and independently among the different groups, stepwise linear discriminant analysis was performed for all the variables that showed p< 0.15 by unvariate analysis. RLP-C was selected as an independent discriminator between the control and patient groups. RLP-C levels showed a strong positive correlation with trigylceride levels in the control, CAD and DM groups (r= 0.783, r = 0.610 and r= 0.746, respectively). In overall groups, apo ε4 and ε2 carrier genotypes showed a significant increase in RLP-C levels compared with ∊3/3 wild-type (p = 0.0085). After adjusting for the effect of apo E genotypes, a significant increase of the RLP-C levels in the disease groups remained. In conclusion, RLP-C was determined to be an independent risk factor in Korean patients with CAD and NIDDM and showed a strong correlation with triglyceride levels. We suggest that the increased cardiovascular risk associated with the ε4 and ε2 allele may be mediated by more atherogenic RLP-C.
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June 1, 2005
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The red blood cell osmotic fragility test is based on the measure of the resistance of red blood cells to lysis as a function of decreasing NaCl concentration. Up to now, several methods have been used for recording these data, but for the first time, the human red blood cell osmotic fragility confidence interval using the Orcutt mathematical model was determined. The absorbance of the hemoglobin measured at 540 nm, released by the red blood cells of 40 healthy adult individuals, was fitted to the equation Absorbance= p3 erfc ([NaCl] − p1/p2 ); p3 measures one half the absorbance produced by maximum red blood cell hemolysis, p1 is the [NaCl] producing 50% red blood cell hemolysis, and p2 is the dispersion in [NaCl] producing red blood cell hemolysis. Confidence intervals (mean±SD) for the three parameters were as follows: p1 =4.2718±0.1848; p2 = 0.1947±0.0391, and p3 =0.5568+0.0426. The usefulness of this osmotic fragility data analysis method using two pathological samples (β-thalassemia minor and hereditary spherocytosis) was demonstrated. Parameters of the fitted data were compared with those obtained by the conventional recording method of Beutler.
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June 1, 2005
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Serum transferrin receptor is considered as a reliable marker of iron status particularly when iron deficiency is associated with chronic disorders such as inflammation, infection or malignancy. The present study aims to illustrate the performances of a new fully automated assay using immunonephelometry. The intra—and between-assay precision was found to be very good (CVs < 4%). In healthy subjects there was no statistically significant difference between men and women. With a cut-off of 1.76 mg/l for diagnosing iron deficiency either alone or combined with anemia of chronic diseases, the sensitivity and specificity were respectively 82% and 96.8%. Unlike conventional biochemical and hematological tests, soluble transferrin receptor was unaffected by confounding pathologies. In genetic hemochromatosis the concentration of soluble transferrin receptor was mostly decreased due to the regulatory effect of iron intracellular level. Our study confirms the reliability of soluble transferrin receptor for the assessment of iron status. It is now possible to assay soluble transferrin receptor, ferritin and transferrin on the same apparatus within 15 minutes.
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June 1, 2005
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An increasing number of women is treated with adjuvant cyclophosphamide, methotrexate and 5-fluorouracil therapy for breast cancer. The effects of the chemotherapy on many laboratory tests are, however, inadequately known. This study investigates the effects of the treatment on various laboratory tests. Fifteen premenopausal women receiving adjuvant cyclophosphamide, methotrexate and 5-fluorouracil chemotherapy and optional radiotherapy were included in the study. Common hormonal, biochemical, hematological, protein and lipid laboratory tests were taken serially during a 10-month follow-up. Twelve women became amenorrheic. Their serum follicle stimulating hormone and luteinising hormone concentrations increased accordingly. Other serum hormones (testosterone, androstenedione, sex hormone-binding globulin, prolactin, dehydroepiandrosterone sulfate, cortisol, parathyroid hormone and thyroid hormones) changed only slightly. Hemoglobin concentration and white blood cell count decreased slightly. Serum alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, creatine kinase, angiotensin-converting enzyme, amylase, glucose, potassium, phosphate, urea and triglycerides concentrations increased slightly whereas serum bilirubin, haptoglobin, and immunoglobulin A and M decreased slightly. Serum α 1 -antitrypsin fluctuated around the baseline concentration. Other test results remained at their pretreatment concentrations. With the exception of increases in serum gonadotrophins, the changes observed were slight and the mean concentrations remained within reference limits. Therefore, cyclophosphamide, methotrexate and 5-fluorouracil adjuvant treatment is unlikely to complicate the diagnosis of other diseases.
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June 1, 2005
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The variability of the tumor markers cancer antigen (CA) 15.3, carcinoembryonic antigen (CEA) and tissue polypeptide antigen (TPA) during steady state concentrations and the rate of increase during progression is described. One hundred and ninety-two patients were monitored during first-line chemotherapy for metastatic breast cancer and during follow-up. Blood specimens were sampled approximately every four weeks. Steady state concentrations were registered for 77 (CA 15.3), 96 (CEA), and 127 (TPA) patients with below cutoff level values and for 28 (CA 15.3), 25 (CEA), and 11 (TPA ) patients with above cutoff level values. Clinical and marker progression was registered for 75 (CA 15.3), 62 (CEA), and 57 (TPA) patients. The coefficients of total variation of steady state concentrations (comprising the intra- and interassay analytical imprecision and the within subject biological variation) were higher below (14.9% CA 15.3, 15.4% CEA, 25.9% TPA) than above cutoffs (9.6% CA 15.3, 6.0% CEA, 19.9% TPA). The variability was similar for CA 15.3 and CEA but higher for TPA. During progression the rates of increase in concentrations were similar for CA 15.3 (0.0257) and CEA (0.0214) and lower than for TPA (0.0346). Our data indicate that criteria for assessment of sequential tumor marker concentrations should consider the marker in question, the steady state variability, the cutoff value, and the rate of increase during disease progression.
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June 1, 2005
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The performance of the Olympus AU 600, a newly available open multiparametric analyzer, available for routine biochemical analysis of biological samples, was evaluated. The analytical and technical performance of the apparatus and the quality of the Olympus reagents were both examined in a single site study. Electrolyte concentrations were determined with patented ion-selective electrodes; substrate concentrations and enzyme activities were determined by spectrophotometric measurement after coloured reaction or UV detection-based-reactions. The protocol of the evaluation and the acceptability criteria were those recommended by the French Society for Clinical Biology. For the parameters studied, the upper limits of linearity were equal to or higher than those claimed by the manufacturer. The CV values for within-run and between-run precision were lower than the target values with few exceptions. The comparison study gave satisfactory results for most of the parameters. Only expected interferences occurred. In summary, the results obtained for the 25 parameters studied and the characteristics of the apparatus were satisfactory. The analyzer is rapid (800 to 1200 tests per hour) and easy to use. In addition, the analyzer complies with good analytical practice and its flexibility enables users to plan work according to local laboratory constraints.
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June 1, 2005
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June 1, 2005
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July 27, 2005
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