Volume 46, Issue 1

No Abstract available

Addition of the measurement of creatinine concentration in whole blood on the ABL837 FLEX blood gas analyzer (Radiometer Medical ApS, Copenhagen, Denmark) allows fast and reliable reporting of creatinine in point-of-care testing (POCT). The new creatinine sensor follows the international recommendations of the National Kidney Disease Education Program Laboratory Working Group as of January 2006 with respect to acceptable performance, reference method and traceability. Validation tests show that the creatinine sensor has excellent performance and thus has the potential to change the poor track record of creatinine testing in plasma and whole blood in both the clinical laboratory and POCT. This article describes the clinical needs and the methods currently available for creatinine measurement and presents performance tests carried out by the manufacturer. Clin Chem Lab Med 2008;46:3–8.

Background: Modern blood gas analyzers are often coupled to electrolyte and metabolite analyzers. We evaluated a Stat Profile Critical Care Xpress analyzer (STP CCX) for the rapid point-of-care measurement of blood gases (pH, pCO 2 , pO 2 , sO 2 ), hematocrit (Hct), total hemoglobin (tHb), sodium (Na + ), potassium (K + ), chloride (Cl – ), glucose (Glu), lactate (Lac), urea (BUN), ionized calcium (iCa) and ionized magnesium (iMg). Methods: The analyzer was evaluated in terms of imprecision and recovery using the STP CCX control. Fresh blood samples were also measured to determine the between-day imprecision. Correlation was assessed by clinical sample comparison with the Nova Stat Profile Ultra C and Dimension RxL systems for Cl – and BUN. We used Deming regression, correlation coefficients, mean differences, and the Wilcoxon signed-rank test for data analysis. Results: The coefficients of variation for all analytes were within desirable limits, ranging from 0.1% to 4.3%, and the recovery was 100%±3%. Between-day imprecision using fresh blood samples showed good results, ranging from 0.2% to 3.4%. The comparison results showed high to very high correlation. However, statistically significant mean differences with large bias were found for pCO 2 , pO 2 and Cl – . Conclusions: This analyzer is suitable as a simple and fast diagnostic tool in the laboratory and the critical care unit. However, users should be aware of biases that may lead to clinically significant errors in the assessment of acid-base status. Clin Chem Lab Med 2008;46:9–14.

Background: Total carbon dioxide content (TCO 2 ) can be calculated from measured values of pH and pCO 2 according to a simplified and standardized form of the Henderson-Hasselbalch equation, or measured directly. Methods: We assessed the agreement between calculated TCO 2 and measured TCO 2 using a total of 74 blood samples. Calculated TCO 2 was obtained using blood gas analysis of pH and pCO 2 in arterial whole blood on a Nova Stat Profile Critical Care Xpress analyzer. Measured TCO 2 was determined using a Dimension RxL analyzer on arterial plasma, and was used as the comparative method. Deming regression analysis, correlation coefficients, bias (Bland-Altman method) and Student's t-test were used for statistical analysis. Results: Deming regression analysis showed a high degree of correlation between calculated and measured TCO 2 (r=0.97). The slope (0.96; 95% CI=0.90– 1.02) of the regression line was close to 1 with a positive intercept (2.86 mmol/L; 95% CI=1.44–4.27), and the standard error of the estimate was 0.20 mmol/L. The mean bias was 1.94 mmol/L with a standard deviation of 1.69 mmol/L. The pCO 2 values showed a significant effect on calculated TCO 2 . Most paired differences were within the 95% limits of agreement (−1.45 to 5.33 mmol/L). Conclusions: Calculated TCO 2 determined using blood gas analysis agreed with measured TCO 2 and may be used to assess acid-base imbalance. However, clinicians should be cautious if using this calculated value in the critically ill patient. Clin Chem Lab Med 2008;46:15–7.

No Abstract available

Analyzers with ion-selective electrodes (ISEs) for ionized magnesium (iMg) should yield comparable and unbiased results for iMg. This IFCC guideline on sampling, measuring and reporting iMg in plasma provides a prerequisite to achieve this goal [in this document, “plasma” refers to circulating plasma and the forms in which it is sampled, namely the plasma phase of anticoagulated whole blood (or “blood”), plasma separated from blood cells, or serum]. The guideline recommends measuring and reporting ionized magnesium as a substance concentration relative to the substance concentration of magnesium in primary aqueous calibrants with magnesium, sodium, and calcium chloride of physiological ionic strength. The recommended name is “the concentration of ionized magnesium in plasma”. Based on this guideline, results will be approximately 3% higher than the true substance concentration and 4% lower than the true molality in plasma. Calcium ions interfere with all current magnesium ion-selective electrodes (Mg-ISEs), and thus it is necessary to determine both ions simultaneously in each sample and correct the result for Ca 2+ interference. Binding of Mg in plasma is pH-dependent. Therefore, pH should be measured simultaneously with iMg to allow adjustment of the result to pH 7.4. The concentration of iMg in plasma may be physiologically and clinically more relevant than the concentration of total magnesium. Furthermore, blood-gas analyzers or instruments for point-of-care testing are able to measure plasma iMg using whole blood (with intact blood cells) as the sample, minimizing turn-around time compared to serum and plasma, which require removal of blood cells. Clin Chem Lab Med 2008;46:21–6.

This review focuses on (i) the current status of 1 H NMR spectroscopy to quantify lipoprotein subclasses directly from serum or plasma, and (ii) the applications of 1 H NMR metabonomics of serum in biomedicine. Related to both themes, experimental and data analysis methodologies are discussed together with the biochemical rationales. Particular emphasis is placed on the concepts of risk assessment and diagnostics in relation to the potential clinical role of 1 H NMR metabonomics; recent applications in the area of coronary heart disease and diabetes are addressed in more detail. Clin Chem Lab Med 2008;46:27–42.

Incretins such as glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) are intestinal hormones that are released in response to ingestion of nutrients, especially carbohydrate. They have a number of important biological effects, which include release of insulin, inhibition of glucagon and somatostatin, maintenance of β-cell mass, delay of gastric emptying, and inhibition of feeding. These properties allow them to be potentially suitable agents for the treatment of type 2 diabetes (T2D). Incretin receptors are also present in other parts of the body including the brain, where their effects are beginning to be understood and their relevance to disorders of nutrition and ageing are being explored. There is currently a pandemic of obesity and diabetes, and existing treatments are largely inadequate in regard to efficacy as well as their ability to tackle important factors in the pathogenesis of T2D. There is increasing evidence that current treatments do not address the issue of progressive β-cell failure in T2D. As obesity is the engine that is driving the epidemic of diabetes, it is disappointing that most treatments that succeed in lowering plasma glucose are also associated with weight gain. It is now well established that intensively treated T2D has a better outcome than standard treatment. Consequently, achieving better control of diabetes with lower HbA1c is the goal of optimal treatment. Despite the use of usual therapeutic agents in T2D, often in high doses and as combinations, such as metformin, sulphonylurea, α-glycosidase inhibitors, thiazolidinediones and a number of animal and human insulin preparations, optimal control of glycaemia is not achieved. The use of incretins as therapeutic agents offers a new approach to the treatment of T2D. Incretin metabolism is abnormal in T2D, evidenced by a decreased incretin effect, reduction in nutrient-mediated secretion of GIP and GLP-1 in T2D, and resistance to GIP. GLP-1, on the other hand, when administered intravenously in T2D is able to increase insulin secretion and improve glucose homeostasis. As GLP-1 has a very short half-life, due to rapid degradation by the enzyme dipeptidyl peptidase IV (DPPIV), analogues of GIP and GLP-1 that are resistant to the action of DPPIV have been developed and clinical trials have shown their effectiveness. Another novel agent, naturally resistant to DPPIV that is given by subcutaneous injection is a synthetic peptide called exenatide, has recently been approved for treatment of T2D in the USA. Efforts are underway to develop agents that can be given orally and include a DPPIV inhibitor that has been licensed for the treatment of T2D in the USA, and several other agents are undergoing clinical trials. Strategies to augment the biological actions of GIP and/or GLP-1 in T2D are expected to minimise weight gain, reduce hypoglycaemic episodes and prevent progressive β-cell failure by increasing β-cell mass. The optimal agent(s) that may mimic and replace the endogenous incretin effect is not fully known and awaits the outcome of clinical trials that are still ongoing. The potential therapeutic role in non-diabetic states, including obesity and neurodegenerative disease, is intriguing and depends upon results from ongoing research. Clin Chem Lab Med 2008;46:43–56.

Background : Matrix metalloproteinase-9 (MMP-9) is involved in the degradation of the extracellular matrix during physiological and pathological processes. Two functional polymorphisms [C –1562 T and microsatellite (CA) 13–25 ] in the promoter region of the MMP-9 gene have been associated with several diseases. The aim of this study was to examine whether these MMP-9 polymorphisms and haplotypes are linked with plasma MMP-9 variations in healthy subjects. Methods : We studied 177 healthy male white volunteers (age range 20–55 years) who were non-smokers and not taking any medication. Genomic DNA was extracted from whole blood and genotypes for the C –1562 T and the microsatellite (CA) n polymorphisms were determined. MMP-9 levels were measured in plasma samples by gelatin zymography. Results : The frequency of the alleles C and T for the C –1562 T polymorphism were 90% and 10%, respectively. The frequency of the alleles with less than 21 CA repeats (L) and with 21 repeats or higher (H) were 47% and 53%, respectively. We found no differences in plasma MMP-9 levels among the genotype groups or among different haplotypes (all p>0.05). Conclusions : These findings suggest that functional polymorphisms in the promoter of the MMP-9 gene are not linked with significant plasma MMP-9 variations in healthy subjects. Clin Chem Lab Med 2008;46:57–63.

Background : The association of genetic profiles with biological or clinical assessments is not clearly established especially among apparently healthy subjects. Methods : A multivariate statistical analysis was performed on 24 polymorphisms related to the main metabolic pathways involved in cardiovascular diseases (CVDs). They were collected among 1551 healthy subjects of the Stanislas cohort to obtain genetic profiles. Association with biological variables was then studied at baseline (t 0 ) and 5 years later (t 5 ). Results : Six genetic clusters were identified with relevant profiles and five polymorphisms from the selectin, apolipoprotein C3 and lipoprotein lipase genes ( SELE- 98G/T, APOC3– 3175C/G, APOC3 –482C/T, APOC3– 1100C/T, LPL –93T/G) were sufficiently characteristic to associate 99.6% of the subjects with their corresponding cluster. A 5-year follow-up showed that clinical and biological measurements in relation to CVD risk factors already differ with triglyceride (p=0.009 for t 0 and p=0.005 for t 5 ) and high-density lipoprotein cholesterol (p=0.014 for t 0 and p=0.003 for t 5 ) for these previous genetic clusters. Conclusions : This study presents the hypothesis that SELE could be protective, whereas APOC3 could be associated with risk. It remains to be seen whether these polymorphisms will be predictive of CVD events among the selected clusters of different metabolic subtypes after a 10-year follow-up. Clin Chem Lab Med 2008;46:64–72.

Background : The rationale behind this study was to examine the relationship between polymorphisms in genes that regulate remethylation of homocysteine to methionine, i.e., methionine synthase ( MTR A2756G ) and methionine synthase reductase ( MTRR A66G ), and risk of deep vein thrombosis (DVT) in a South Indian cohort (163 DVT cases and 163 controls), as elevated homocysteine has been documented as an independent risk factor for DVT in the same cohort. Methods : Plasma homocysteine analysis was carried out by reverse phase HPLC. The MTR A2756G and MTRR A66G genetic polymorphisms were detected using PCR-restriction fragment length polymorphism method. For statistical analyses, Fisher's exact test was used for categorical variables and Student's t-test and analysis of variance were used for continuous variables. Results : The MTRR 66GG genotype was associated with a 2.74-fold [95% confidence interval (CI): 1.73, 4.34] risk of DVT. The MTR A2756G polymorphism was not a risk factor. MTRR GG/MTR AG and MTRR GG/MTR GG genotypes cumulatively were found to increase the risk of DVT by 2.38-fold (95% CI: 1.43, 3.96). A positive association was observed between plasma homocysteine and the MTRR G allele, and the MTR G allele was shown to have an additive effect. The risk associated with the MTRR 66GG genotype was further increased in subjects compound heterozygous for methylene tetrahydrofolate reductase ( MTHFR ) [odds ratio (OR): 3.46, 95% CI: 1.38, 8.63]. Conclusions : The MTRR 66GG genotype is a risk factor for DVT among South Indians. This risk is increased further in the presence of the MTHFR 677CT / 1298AC genotype. Clin Chem Lab Med 2008;46:73–9.

Background : We required a new genotyping method for the diagnosis of adult hypolactasia, which would allow the simultaneous genotyping of three known polymorphic loci linked to lactose tolerance ( LCT –13907C>G, LCT –13910C>T and LCT –13915T>G) in a single PCR/pyrosequencing test run. Method : We utilized Pyrosequencing™ technology, a DNA-sequence-by-synthesis technique. Results : The developed Pyrosequencing™ method allowed genotyping of the three loci LCT –13907C>G, LCT –13910C>T and LCT –13915T>G in a single PCR/pyrosequencing test run. A separate Pyrosequencing™ assay was developed for genotyping of the LCT –14010G>C mutation. The methods were evaluated in 116 clinical samples from patients of non-European descent, sent to the laboratory for diagnosis of adult hypolactasia. The “African” mutations LCT –13907C>G and LCT –13915T>G were found in subjects originating not only from Somalia, Ethiopia and Eritrea but also in Arabs and Iranians. Several compound heterozygotes LCT –13907CG/–13915TG were found among Ethiopian, Eritrean and Somalian subjects. No subject with the LCT –14010G>C mutation was found among the studied subjects. Advantages compared to the other genotyping methods are less staff hands-on time than, e.g., restriction fragment length polymorphism (RFLP) analyses, avoiding radioactivity as in the originally described isotope-minisequencing and in addition, Pyrosequencing™ is a direct DNA sequencing technique which gives unambiguous genotyping results as well as some redundant sequence information beyond the single nucleotide polymorphism (SNP) position, which serves as a valuable internal control obtained for each sample. Conclusions : Pyrosequencing™ is a robust genotyping modality suitable for clinical genotyping of patients not only of European, but also of African or Middle Eastern descent, who may harbor any combination of the three LCT mutations, LCT –13907C>G, LCT –13910C>T, LCT –13915T>G. Clin Chem Lab Med 2008;46:80–4.

Background : The VCS technology of Beckman Coulter differentiates white blood cells based on measures of their volume, conductivity and light scatter. The current study investigated the predictive value of index measures, known as research population data, for the detection of chronic lymphatic leukemia and myelodysplastic syndrome. Methods : Blood cell counts were performed in samples from 44 patients with chronic lymphatic leukemia, 19 patients with myelodysplastic syndrome and 199 healthy blood donors using the Beckman Coulter LH750. Means and standard deviations of volume, conductivity and scatter of lymphocytes and neutrophils were evaluated as predictors for both diseases. Their specificity and selectivity were evaluated by logistic regression and receiver operating characteristic curve analysis. Results : Research population data were significantly different among groups. For chronic lymphatic leukemia, standard deviations of lymphocytes scatter and volume showed most relevant differences in comparison to healthy blood donors (sensitivity 88.6%, specificity 84.4%). For myelodysplastic syndrome, standard deviations of neutrophils conductivity were most predictive (sensitivity 73.7%, specificity 93.0%). Areas under corresponding receiver operating characteristic curves were 0.941 and 0.951, respectively. Conclusions : Based on their high predictive value, research population data could be routinely used to screen for chronic lymphatic leukemia and myelodysplastic syndrome. Clin Chem Lab Med 2008;46:85–8.

Background : Saliva is one of the most promising and easy-to-collect source of potential biomarkers of oral and systemic disease. We standardized a protocol suitable for pre-analytical treatment and for the analysis of whole normal saliva by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF/MS). Methods : We evaluated the impact of storage time, freeze/thaw cycles, denaturing agents, glycoproteins depletion, centrifugation, type of matrix and ProteinChip ® used on the quality of the SELDI protein profile. Moreover, we explored the inter-individual and between-sex differences and the changes in the sample composition over the day. Results : Saliva was qualitatively stable, in the absence of protease inhibitors, for up to 3 h from the collection at room temperature, although the intensity of a number of peaks slightly decreased between 0 and 3 h and the addition of protease inhibitors did not completely revert this trend. The saliva proteome changed during the day and showed relevant between-sex differences. The protein profile remained stable for up to five freeze/thaw cycles. The addition of denaturing solutions and the depletion of glycoproteins improved the quality of the spectra without affecting their reproducibility. Conclusions : We defined a protocol that improved the quality and the reproducibility of SELDI-TOF/MS analysis, thus potentially supporting the search for putative biomarkers of disease. Clin Chem Lab Med 2008;46:89–99.

Background : This study aims at showing the effect of hypokinesia (HK) on sodium (Na + ) loss with different muscle Na + deficiency and different Na + intake. Muscle Na + content, plasma Na + level and Na + loss with and without Na + supplementation were measured. Methods : This study was conducted on 40 healthy male volunteers during a pre-experimental and an experimental period. Subjects were equally divided into four groups: unsupplemented active control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented active control subjects (SACS) and supplemented hypokinetic subjects (SHKS). A daily supplementation of 3.21 mmol of sodium chloride (NaCl) per kg body weight was given to subjects in the SACS and SHKS groups. Results : Muscle Na + content levels decreased and plasma Na + levels, and levels of Na + loss in urine and feces increased (p<0.05) in the SHKS and UHKS groups compared to their pre-experimental values and the values in the respective active control groups (SACS and UACS). However, muscle Na + content levels decreased more (p<0.05), and plasma Na + levels and levels of Na + loss in urine and feces increased more (p<0.05) in the SHKS group than in the UHKS group. Conclusions : The greater muscle Na + deficiency with higher than lower Na + consumption shows that the risk of greater muscle Na + deficiency is directly related to Na + consumption. The higher Na + loss with higher than lower muscle Na + deficiency shows that the risk of greater muscle Na + loss is directly related to muscle Na + deficiency. It is concluded that muscle Na + deficiency is more evident when Na + consumption is higher and that muscle Na + loss was more exacerbated with higher than lower muscle Na + deficiency indicating that during prolonged HK the muscle Na + deficiency is due to the inability of the body to use Na + , but not to Na + shortage in diet. Clin Chem Lab Med 2008;46:100–6.

Background : Reactive oxygen species produced either endogenously or exogenously can attack lipids, proteins and DNA in human cells and cause potentially deleterious consequences. In recent years, their role in the pathogenesis of lung cancer and the preventive effect of antioxidants have been studied extensively. In this study, our aim was to investigate the levels of 8-hydroxy-2′-deoxyguanosine (8OHdG) and malondialdehyde as a marker for the effects of reactive oxygen species on DNA and lipids, the levels of antioxidant vitamins and the correlations between these oxidative stress markers and antioxidants in lung cancer. Methods : Serum malondialdehyde, β-carotene, retinol, and vitamins C and E were measured by high-performance liquid chromatography methods in fasting blood samples and 8OHdG was measured by gas chromatography-mass spectrometry in 24-h urine samples of patients with lung cancer (n=39) and healthy controls (n=31). Results : The levels of 8OHdG and malondialdehyde were significantly higher (p<0.05 and p<0.005, respectively) and β-carotene, retinol, and vitamins C and E (p<0.0001, p<0.0001, p<0.0001, and p<0.05, respectively) were significantly lower in patients than in controls. There was a significantly positive correlation between 8OHdG and malondialdehyde (r=0.463, p=0.01) and a negative correlation between the levels of 8OHdG and retinol (r=–0.419, p=0.021) in the patient group. Conclusions : Our results demonstrate that the oxidant/antioxidant balance was spoiled in favor of lipid peroxidation and DNA damage in lung cancer patients. Significant increases in the levels of malondialdehyde and 8OHdG and decreases in the levels of antioxidants suggest the possible involvement of oxidative stress in lung cancer. Clin Chem Lab Med 2008;46:107–12.

Background : Paraoxonase is high-density lipoprotein (HDL)-associated esterase/lactonase implicated to play a role in the antioxidant and anti-inflammatory properties exerted by HDL. Increasing evidence support a role of free radicals and oxidative stress in neuronal damage induced by ischemia-reperfusion. The aim of this study was to further investigate the relationship between lipoprotein oxidative damage and stroke. Methods : We compared the paraoxonase activity and levels of lipid hydroperoxides in plasma isolated from healthy subjects (n=50) and from stroke patients (n=49). Moreover, the correlations between biochemical markers and the National Institute of Health Stroke Scale (NIHSS), which is widely used to study neurological severity, were evaluated. Results : Our results demonstrated, for the first time, that the activity of paraoxonase in plasma of stroke subjects was significantly lower than controls (p<0.001) and the levels of lipid hydroperoxides were significantly higher in plasma from patients (p<0.001). Moreover, using linear regression analysis, significant correlations between the activity of paraoxonase, lipid peroxidation and the severity of neurological deficit at admission were observed. Conclusions : These results provide further evidence that oxidative stress and impairment of the antioxidant system may play a role in stroke. Antioxidant activity of plasma may be an important factor providing protection from neurological damage caused by stroke-associated oxidative stress. Clin Chem Lab Med 2008;46:113–7.

Background : The main objectives of our study were to determine whether resistin was present in human breast milk and to assess resistin status in breast milk and serum in breastfeeding women for up to 180 days post-partum. Methods : Blood and breast milk samples were collected from 160 breastfeeding women enrolled on 1–3, 4–14, 15–30, 31–90 or 91–180 post-partum days. Blood samples were collected from 48 breast-fed infants at 8–24 days after birth. Milk and serum resistin levels were measured by ELISA. Results : Serum and breast milk resistin concentrations were highest (5800±1100 and 1710±68 pg/mL, respectively) at 1–3 post-partum days and decreased to 1645±210 and 1130±115 pg/mL, 1600±105 and 710±25 pg/mL, 1980±155 and 595±20 pg/mL and to 2060±300 and 670±18 pg/mL at 4–14, 15–30, 31–90 and 91–180 post-partum days, respectively. Serum resistin concentrations were correlated with those of milk (r=0.822, p<0.001). Both milk and serum resistin concentrations were correlated positively with maternal serum estradiol, progesterone, prolactin, thyroxine, triiodothyronine, cortisol, leptin and C-reactive protein concentrations. Serum resistin concentration in breast-fed infants (4915±340 pg/mL) was higher than that observed in their consumed breast milk (1745±70 pg/mL, p<0.001) or in serum of their breastfeeding mothers (3760±360 pg/mL, p<0.05). Conclusions : Resistin is present in human breast milk and its concentration in breast milk decreases with time during lactation. Its concentrations in breast milk and serum are correlated with circulating levels of various reproductive and metabolic hormones and with those of the general inflammatory marker, C-reactive protein. Clin Chem Lab Med 2008;46:118–24.

Background : Obesity and homocysteine are important risk factors for cardiovascular disease. The relation between pattern of obesity and homocysteine is unclear. The objective of this study was to investigate the relation between pattern of obesity and plasma total homocysteine (tHcy) level in male patients with coronary artery disease (CAD). Methods : A total of 63 male patients (mean age 66.2 years) with angiographically documented CAD were enrolled. Overnight fasting blood samples were measured for plasma tHcy, serum folic acid and serum vitamin B 12 levels. Anthropometric measurements included waist-to-hip ratio (WHR) and body mass index (BMI). Results : The mean WHR was 0.90±0.05, mean BMI 24.6±3.3 kg/m 2 and the mean plasma tHcy level 11.6±3.2 μmol/L. In univariate analysis, plasma tHcy level correlated significantly with serum vitamin B 12 level, serum folic acid level, WHR, estimated creatinine clearance, aspirin use and fibrate use. There was no significant association between plasma tHcy level and BMI. In multivariate analysis, only WHR (β-value 22.263, p<0.001), serum level of vitamin B 12 (β-value –0.004, p=0.003), estimated creatinine clearance (β-value –4.154, p=0.003) and use of fibrates (β-value 2.307, p=0.031) were independent predictors of plasma tHcy level. Conclusions : WHR, but not BMI, is a strong independent predictor of plasma tHcy level in male patients with CAD. Clin Chem Lab Med 2008;46:125–30.

Background : Pleomorphic adenoma (PA) is a benign tumour of the salivary gland with a tendency to malignancy which creates many diagnostic problems. N-Acetyl-β-hexosaminidase (HEX) is a lysosomal exoglycosidase involved in degradation of oligosaccharide chains of glycoproteins, glycolipids and glycosaminoglycans, known as a potential tumour marker. In the majority of tissues and body fluids, HEX exists as two major isoenzymes: HEX A and HEX B. The aim of our study was to evaluate HEX A and HEX B activity in healthy and PA human salivary glands using colorimetric and isoelectrofocusing methods. Methods : PA (n=8) and macroscopically unchanged salivary glands (n=8), served as controls, were used for the study. After preliminary preparation, isoenzymes of HEX were determined by colorimetric and isoelectrofocusing methods. Results : Total activity of HEX, as well as HEX A and HEX B, in PA specimens determined by a colorimetric method was significantly higher compared with normal human salivary gland specimens. After isoelectrofocusing, in normal human salivary and PA glands, two sets of HEX isoforms were found corresponding to HEX A and HEX B. There was no significant difference in the amount of HEX A and HEX B isoforms. In PA tissue, activities of HEX isoforms in the pI ranges 1, 3b, 6 and 8 were significantly lower, and in ranges 5 and 8 significantly higher than in normal tissue. The observed significant shifts were localised mostly in HEX B activity area. Conclusions : The present data indicate that HEX activity and activity of its isoenzymes in tumour specimens is significantly and consistently elevated, and thus suggest the need for further studies on the degradation of glycoconjugates, both in healthy salivary glands and PA. It appears that HEX may be considered as a new tumour marker in these salivary gland diseases. Clin Chem Lab Med 2008;46:131–6.

Background : We investigated whether the activities of erythrocyte membrane acetylcholinesterase (AChE), Na + , K + -ATPase and Mg 2+ -ATPase are modulated in basketball players pre- vs. post-forced training with or without L-carnitine (L-C) supplementation. Methods : Blood was obtained from 10 male players pre-game (group A) and post-game (group B) and after 1 month L-C supplementation (2 g/24 h orally) pre-training (group C) and post-training (group D). Lactate, pyruvate and total antioxidant status (TAS) were measured with commercial kits, catecholamines with HPLC and the enzyme activities spectrophotometrically. Results : Lactate, pyruvate, AChE, Na + , K + -ATPase and catecholamines were increased (p<0.001) and TAS was decreased (p<0.001) in group B. In contrast, TAS remained unaltered and the all enzyme activities were reduced (p<0.001) in group D at the same time of study. Mg 2+ -ATPase activity remained unchanged. In vitro incubation of the modulated AChE and Na + , K + -ATPase with L-C (25 μM) from group B and group D resulted in a non-significant reduction of the enzymes in group B and complete restoration of their activities in group D. Conclusions : The increase of AChE and Na + , K + -ATPase activities may be due to the elevation of catecholamines in group B. Carnitine utilization by the muscles during training may result in a reduction of the enzyme activities (group D). The latter is supported by the recovery of the enzyme activities after incubation of the membranes from group D with L-C. Clin Chem Lab Med 2008;46:137–42.

Background : The main prevention of chronic diabetic complications is maintaining near normoglycemia. In this study, evaluation of analytical performance of the Optium Xido blood glucose meter designed for patients' self-monitoring of glycemia was carried out. Methods : Glucose concentrations were measured in 118 EDTA blood samples using the Xido glucose meter and the GOD/PAP method on a Modular P clinical analyzer. The results obtained were used for the assessment of accuracy, precision and linearity. Performance of the Xido glucose meter was also assessed using four different reagent strip lots, and the between-lot variation was calculated. Results : The within-run imprecision coefficient of variation (CV) amounted to 4.2%. Good response linearity was found in glucose concentrations of 31–444 mg/dL (1.7–24.7 mmol/L). In the concentration range studied, the glucose meter error was 5.14% and the linear regression equation was y=0.91x+6.2, (r=0.984). The Passing-Bablok agreement test indicated good concordance of results. However, for glucose concentrations <100 mg/dL (5.6 mmol/L) (n=69) the error was 6.82% with regression equation y=0.86x+5.9 (r=0.757). Between-lot differences amounted to 0.7%–18.2%. Conclusions : The Xido glucose meter has good precision and accuracy when compared to the laboratory method and meets the quality recommendations of the National Committee of Clinical Laboratory Standards (NCCLS, currently the Clinical Laboratory Standards Institute), the National Academy of Clinical Biochemistry (NACB) and the International Organization for Standardization (ISO). However, between-lot variability may result in differences between day-to-day results when the device is continuously used. Therefore, the validation of new lots of reagent strips with a laboratory method is recommended. Clin Chem Lab Med 2008;46:143–7.

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No Abstract available