European journal of clinical chemistry and clinical biochemistry : journal of the Forum of European Clinical Chemistry Societies最新文献

The isothermal Primer Oligo Base Extension (PROBE) reaction combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for diagnostic product detection as recently introduced by our group is modified to incorporate temperature cycling during the primer extension step, resulting in enhanced levels of diagnostic product generation. Utilizing temperature cycled PROBE, the identities of two apolipoprotein E polymorphisms (codons 112 and 158) for differentiation of epsilon 2/epsilon 3, epsilon 3/epsilon 3, epsilon 3/epsilon 4, and epsilon 4/epsilon 4 genotypes were simultaneously determined. Primers specific for each site are extended by a series of bases unique to the identity of that variable site, producing low mass diagnostic products (M(r) < 9000) highly amenable to detection by mass spectrometry. The temperature cycled PROBE method has yielded unambiguous and correct diagnoses for all samples tested thus far. The increased amount of diagnostic product generated per primer by the cycling method makes possible faster spectrum acquisition due to the increased signal intensity, critical for future automated measurement of such samples.

The majority of the published reference range data on catecholamines excretion by healthy children is incomplete and often contradictory (1). We assayed in the urines of 127 healthy children the values of the catecholamines (norepinephrine, epinephrine, dopamine) and their methylated metabolites (normetanephrine, metanephrine, 3-methoxytyramine) for the determination of paediatric reference ranges. Data were expressed as micrograms/24 h, mumol/24 h and mmol/mol creatinine. An isocratic HPLC procedure by ion-pair reversed phase chromatography on a C18 column, using a single mobile phase containing formic acid, acetonitrile, diethylamine and octane sulphonic acid (ion pairing agent), permitted the separate assay of the various fractions of total catecholamines. The relations between each biogenic amine and age were studied and reference values were determined as a function of age.

Resistance to activated protein C is a recently detected phenomenon that has gained a rapid acceptance as a major risk factor for venous thromboembolism. The phenotypic expression of resistance to activated protein C is characterized by a poor response to the anticoagulant activity of activated protein C, a key enzyme in the down-regulation of blood coagulation, which causes a disposition for a hypercoagulable state. At least 90% of the cases with resistance to activated protein C are explained by a point mutation in the gene for coagulation factor V, resulting in replacement of an Arg to Gln at position 506 (factor V:Q506, often denoted factor V Leiden), one of the three activated protein C cleavage sites in activated factor V. The mutation is inherited as an autosomally dominant trait and has a prevalence of 2% to more than 10% in the general Caucasian population. A number of clinical studies, using different inclusion criteria, show a prevalence of activated protein C resistance of 20-60% among patients with venous thromboembolism. The actual thrombotic risk is moderate with an odds ratio of 5-7 but its high prevalence makes it by far the most important inherited risk factor known today, even higher than the sum of contributions from inherited deficiencies of antithrombin, protein C and protein S. Recent data suggest that activated protein C resistance, which is not due to factor V:Q506 and which appears to be acquired, is also a risk factor for venous thrombosis and for cerebral ischaemic disease. A decreased response to activated protein C is common during pregnancy and during use of oral contraceptives, but the clinical relevance of these findings have yet to be determined. The activated protein C resistance phenotype is typically diagnosed with an activated partial thromboplastin time-based assay, which detects factor V:Q506-dependent as well as acquired activated protein C resistance. However, the sensitivity and specificity for the factor V mutation are usually below 90%. Coagulation instruments with a turbidimetric or photometric clot detection principle generally provide a better performance as compared to electromechanical instruments. The activated partial thromboplastin time test requires careful control of preanalytical variables and platelet contamination should be below 1% since otherwise a falsely low activated protein C response will be obtained. A sensitivity and specificity of close to 100% for factor V:Q506 is obtained in a modified activated partial thromboplastin time test using predilution of sample plasma with factor V deficient plasma. The influence of preanalytical variables in this assay is minor. A number of polymerase chain reaction-based methods, some of them allele-specific, have been published, which provide convenient and objective confirmation of the factor V mutation. Thrombotic events are often triggered through the presence of a combination of inherited and circumstantial risk factors. The high prevale

European experts in clinical laboratory sciences have different backgrounds, and development of expertise in this field started more than 100 years ago. Specific national activities have created the heterogeneity that now exists amongst the academic professional membership of more than 40 scientific societies in Europe. The recent political changes have in addition contributed to the rapidly changing profile of Clinical Chemistry and related fields. Based on a questionnaire answered by 31 national representatives, the past, present and future aspects of the European Clinical Laboratory are reviewed. Of the more than 30,000 members of national societies, the majority studied medicine (40.1%), chemistry (27.2%) and pharmacy (21.1%) with large national differences in relative percentages. Post-graduate education is provided by two thirds of the national societies. In most European countries the same experts cover not only clinical chemistry but also haematology, haemostaseology, immunology and transfusiology. National quality assurance programmes are said to be established in 25 countries, but mandatory in only 11 of them. Of the future challenges, the implementation of request strategies were named most often, with interpretative reports and preanalytical aspects estimated as similarly important. It was thought that information technology and new scientific developments would make the greatest impact in the coming years, with economic pressure being the major limiting factor. Despite these limitations an increase in the number of tests is anticipated by most representatives, supporting the assumption of an increasing role of the clinical laboratory in future clinical medicine.

The effects of the angiotensin-converting enzyme inhibitor ramipril on thirteen endocrinological tests were evaluated. These tests comprised serum follitropin, lutropin, prolactin, thyrotropin, free thyroxine, total thyroxine, free triiodothyronine, parathyrin, cortisol, testosterone, sex hormone binding globulin, androstenedione and dehydroepiandrosterone sulphate. Eleven hypertensive outpatients, 9 men and 2 women, treated at the department of internal medicine in Turku University Central Hospital, received 5 mg of ramipril once a day for the study period of four weeks. The above mentioned endocrinological tests were performed before and at the end of the ramipril treatment. Ramipril decreased the value of free thyroxine statistically significantly, p = 0.011, from the mean value of 17.1 pmol/l to the mean value of 16.0 pmol/l when measured with Amerlex-MAB* free thyroxine kit. The mean within-subject difference was -1.10 pmol/l with a 95% confidence interval of -1.87 - -0.33 pmol/l. With the AutoDELFIA free thyroxine kit and with the reference method dialysis+RIA no effect was detected. Other endocrinological tests examined were not affected by ramipril. Since the decreasing effect of ramipril on free thyroxine was detected only with Amerlex-MAB* but neither with AutoDELFIA nor with dialysis+RIA, the effect was concluded to be analytical. The underlying mechanism and the component ultimately interfering with the analysis is unknown.

Hen egg yolks have been recognized as convenient source for specific antibodies, although their utility in diagnostic applications has been hampered by the lack of efficient purification methods. In the present study, anti-human parathyrin antibodies were raised in rabbits, hens and mice using synthetic human parathyrin peptide (1-84) as an antigen. The antibodies were affinity purified with amino- (1-30) and carboxy- (49-89) terminal peptides of parathyrin under highly alkaline elution conditions, and were evaluated for their diagnostic value in different combinations in immunoenzymometric assay (IEMA) format. A pair of hen egg yolk antibodies were subjected to further methodological validation in the IEMA that was constructed with the N-terminal capture and C-terminal detection antibodies. The synthetic intact human parathyrin (1-84) peptide served as a standard. This within-day IEMA procedure turned out to be sensitive and it correlated well with the two independent intact parathyrin immunoradiometric assays. As shown in the present study, the immuno affinity purification with the highly alkaline elution conditions provides an efficient method for utilization of hen egg yolk antibodies. This is the first report on an application making use of a combination of two hen egg yolk antibody preparations in measuring a homogeneous protein in human serum.

Unlabelled: For troponin T a characteristic biphasic change in the plasma time-concentration curve has been described, especially in patients with early reperfusion after thrombolytic therapy. As troponin T is bound to myofibrillar structures, treatment strategy or treatment outcome could influence the cumulative plasma release of this protein in a different way compared to the cumulative release of free cytoplasmic cardiac enzymes. The present study is the first study comparing the total quantity of troponin T released by the heart during the first 168 hours after acute myocardial infarction, both in patients treated with thrombolytic therapy (n = 16) and in patients not treated with thrombolytic therapy (n = 7). On the basis of clinical symptoms and coronary arteriogram within 24 hours, the patients treated with thrombolytic therapy were divided into two groups, reperfused (n = 9) and non-reperfused (n = 7). In the patients not treated with thrombolytic therapy, absence of spontaneous early reperfusion was judged only from clinical symptoms. Cumulative troponin T release into plasma was compared to the cumulative release of the cytoplasmic cardiac enzymes creatine kinase (EC 2.7.3.2) and hydroxybutyrate dehydrogenase (EC 1.1.1.27). Cumulative release, i. e., infarct size, was calculated using a two-compartment model for circulating proteins. Mean tissue contents, per gram wet weight, of 156 U/g for hydroxybutyrate dehydrogenase, 2.163 U/g for creatine kinase and 234 microg/g for troponin T, were used to express infarct size in gram-equivalents of healthy myocardium per litre plasma (g-eq/l). Release rates were represented by the ratio of cumulative quantities released in 10 hours and 72 hours for creatine kinase and hydroxybutyrate dehydrogenase and in 10 hours and 168 hours for troponin T.

Conclusions: - Plasma time-concentration curves and release rates of troponin T in patients treated with thrombolytic therapy showing reperfusion differ significantly from those of patients not treated with thrombolytic therapy, showing no reperfusion. - Creatine kinase and hydroxybutyrate dehydrogenase release is completed within 72-100 hours in all patients, whereas troponin T release still continues after 168 hours. - Cumulative troponin T release at 168 hours is only a fraction (around 8%) of cumulative cytoplasmic enzyme release and the percentage released is not influenced by the treatment strategy or outcome, i. e., vessel patency. - Although troponin T release is only a fraction of the cumulative enzyme release (infarct size) there is a highly significant correlation between both, independent of the treatment strategy or treatment outcome.

Intestinal ischaemia/reperfusion causes formation of reactive oxygen intermediates which lead to mucosal cell injury. Glutathione, a scavenger of reactive oxygen intermediates, protects tissues from reactive oxygen intermediate-mediated cell injury. Nitric oxide is a lipophilic gas and its synthesis is stimulated by ischaemic conditions. In this experimental study, we aimed to investigate the role of i. v. L-glutamine infusion on mucosal tissue glutathione and serum nitric oxide concentrations in intestinal ischaemia/reperfusion. External jugular vein of albino rabbits was cannulated with catheter and infused with normal saline at 4 ml/h. After 3 days, they were randomly divided into two main groups. Group 1 (n = 30) received i. v. normal saline alone, group 2 (n = 30) received normal saline + 205 mmol/l glutamine at 4 ml/h for 24 hours. Next, mucosal glutathione and serum nitric oxide concentrations were measured after 0, 30, 60 min of ischaemia/60 min of reperfusion. Basal glutathione concentrations were similar in normal saline alone and normal saline + 205 mmol/l glutamine infusion groups (p > 0.05). At 30 and 60 min of ischaemia/60 min of reperfusion, glutathione concentrations were significantly lower in normal saline-infused rabbits compared to the normal saline + 205 mmol/l glutamine-infused rabbits (p < 0.05). In addition, serum nitric oxide concentrations were found to be significantly increased in rabbits 30 and 60 min after ischaemia/reperfusion when compared to mean basal nitric oxide concentrations obtained from control animals. However, the normal saline + 205 mmol/l glutamine group had lower serum nitric oxide concentrations than did the normal saline alone group. In conclusion, this study revealed that intestinal mucosal glutathione concentrations were significantly higher in glutamine-receiving rabbits than in non-receiving ones. Additionally, it was shown that nitric oxide concentrations increased in ischaemia both in normal saline alone and normal saline + 205 mmol/l glutamine receiving groups, while this increase in nitric oxide was more prominent in the normal saline alone group (p < 0.01). These findings show that glutamine supplementation may protect the small intestine from ischaemia/reperfusion injury and may play a regulatory role in the biosynthesis of nitric oxide.

Activity of serum/plasma beta-N-acetylhexosaminidase (EC 3.2.1.52) was determined by means of a continuous spectrophotometric method using 3,3'-dichlorophenylsulphonphthaleinyl-N-acetyl-beta-D-glucosaminid e as substrate, with very satisfactory results. Incubation of an undiluted aliquot (1 ml) of samples at 52 degrees C for 8 hours with an adjusted pH 5.5-6.0 provoked only the inactivation of isoenzyme A, thus allowing the evaluation of beta-N-acetylhexosaminidase isoenzyme composition. In 25 serum samples from control subjects and pregnant women, a good correlation between the percentage of isoenzyme B obtained by this procedure and the fluorimetric assay of O'Brien et al. (New Engl J Med 1970; 273:15-20) was found (r = 0.983, S(yx) = 1.51), with no statistically significant difference between the means (43.2 vs 42.8%). In 84 healthy adult subjects, an average value of 30.3% for the proportion of isoenzyme B was obtained, with an interval of 25.4-35.0%, in agreement with results reported by other authors.