[Lipemia and bilirubin influences for twenty-four biochemical parameters measurement]. / Interférences de la lipémie et de l'ictère sur le dosage de 24 paramètres biochimiques.

The study of the influence of the lipemia and icterus was performed experimentally for twenty-four biochemistry parameters on the Roche Cobas 6000 CE analyzer. Overloads in Intralipid(®) or ditaurate of bilirubin were performed on several plasma pools. The limit of 10% was chosen to define interference on the measurement. The parameters studied were classified into different categories depending on their measurement is affected or not. Knowledge of these data allows the biologist to adapt its reporting procedures in the case of lactescent and/or icteric samples.

[Comparison of calculated LDL cholesterol (LDL-C) versus measured LDL cholesterol (LDL-M) and potential impact in terms of therapeutic management]. / Évaluation d'une méthode de dosage direct du LDL-cholestérol et de son impact potentiel en termes de prise en charge thérapeutique.

LDL-cholesterol value is one of the criteria used by the Haute autorité de santé (HAS) in the management of patients in primary and secondary prevention with the aim to reduce cardiovascular mortality. In this respect, the recommendations have been established based on target to achieve LDL-cholesterol. Currently in France, the determination of LDL-cholesterol is mainly carried out by the Friedewald formula whose limits are well known. However, reliable methods for the determination of LDL-cholesterol exist. We compared the results of calculated and measured LDL-cholesterol obtained from 444 patients presenting normal triglyceridemia values in terms of ranking relative to the thresholds of the HAS. The correlation between the two methods is quite good, but a significant difference (p <0.0001) was observed between the calculated and measured values of LDL-cholesterol. On the other hand in 17% of cases the classification of subjects will be different, with a majority so overestimation of calculated LDL-cholesterol with respect to measured LDL-cholesterol. This overestimation is not proportional, in fact most values measured LDL-cholesterol, the higher the calculate-measured difference is important. The rating difference is particularly important when subjects have between 1 and 3 factors of cardiovascular risk where the target LDL-cholesterol to achieve is between 1.3 and 1.9 g/L. The management of patients with lipid lowering may potentially be dependent on the method used for the determination of LDL-cholesterol.

[Hemolysis influence on twenty-two biochemical parameters measurement]. / Interférence de l'hémolyse sur le dosage de vingt-deux paramètres biochimiques.

The study of the influence of hemolysis was determined experimentally for twenty two biochemical parameters on the analyzer Cobas 6000 ce (Roche Diagnostics). The addition method of hemolysate was used to create an increasing concentration of hemoglobin ranging from 0 to 2000 µmol/L. The limit of 10% variation was chosen to define the influence of hemolysis on the measurement. The parameters studied were classified into several categories: the parameters for which hemolysis does not influence the measurement: albumin, uric acid, calcium, C-reactive protein, myoglobin, NT -pro BNP, S100 protein, and urea; parameters impacted positively leading to an overestimation of the result: aspartate aminotransferase, total cholesterol, creatine kinase, creatinine, lactate dehydrogenase, magnesium, magnesium, total protein, triglycerides; and negatively impacted settings so causing an underestimation of the result: alanine amino- transferase, gamma glutamyl transferase, lipase, alkaline phosphatase, troponin T hypersensitive. Certain parameters influence of hemolysis varies depending on the magnitude of the measured parameter this interference being observed for normal values but disappearing for pathological values: creatinine, cholesterol, alkaline phosphatase, triglycerides, or the inverse interference is greater than for conventional pathological values: lipase, alanine amino-transferase. Knowledge of this variability interference allows the biologist to adapt its methods of reporting in the case of haemolysed samples.

[Influence of anticoagulant on the plasma level of fifteen biochemical parameters]. / Influence de la nature de l'anticoagulant sur le dosage plasmatique de quinze paramètres biochimiques.

The study of the influence of the anticoagulant used in blood collection tubes to obtain plasma was performed for fifteen biochemical parameters measured with automated Cobas 6000 (Roche Diagnostics). For each parameter tested the entire measurement domain was studied. The comparison of results obtained on plasma blood sample obtained by lithium heparin and EDTA include: correlation, the limits of acceptability in the standards of monitoring and interpretation standards regression defined by the SFBC and analysis of Bland-Altman. The parameters studied were classified into three categories. The parameters for which the assay is not influenced by the nature of the anticoagulant used: apolipoprotéin A1, apolipoprotein B, alanine amino-transferase, creatine kinase, creatinine, total cholesterol, HDL-cholesterol, lipase, NT-Pro BNP, troponine T and urea. The parameters for which the results are underestimated EDTA plasma, including those for which the impact is moderate and for which the interpretive standards are not changed: triglycerides, and those for which performance standards are changed on one or more levels: aspartate aminotransferase and lactate dehydrogenase; and finally the not practicable EDTA plasma parameters: alkaline phosphatase.

Suitability of POC lactate methods for fetal and perinatal lactate testing: considerations for accuracy, specificity and decision making criteria.

BACKGROUND: Point of care (POC) testing for fetal scalp blood lactate is a more user friendly and more successful approach compared to scalp pH for intrapartum fetal monitoring. The aim of this study was to assess the analytical specificity and clinical reliability of three POC lactate methods. METHODS: The analytical performance of three POC lactate methods was compared to Cobas 6000 (Roche Diagnostics) laboratory reference method: Lactate Pro from Arkray, GEM 4000 from Instrumentation Laboratory and StatStrip Lactate from Nova Biomedical. The clinical performance and influences on accuracy and decision making criteria for the three POC methods was assessed with umbilical cord samples and compared to the laboratory reference method. The influence of varying ranges of hemoglobin, pH and partial oxygen pressure (pO(2)) on the accuracy of results was assessed. RESULTS: Although all three POC methods showed good correlation with the reference method for the umbilical cord sample population (r=0.989, 0.973 and 0.980, respectively), Lactate Pro and Gem 4000 showed a significant negative bias compared to the reference method. The degree of bias meant a significant readjustment of decision making criteria was required for fetal lactate use. The accuracy of the Lactate Pro results was affected by hemoglobin and to a lesser extent pH. CONCLUSIONS: The three electrochemical POC devices can measure fetal lactate reliably. StatStrip Lactate showed a closer correlation and concordance to our laboratory reference method. The results of this study indicate the requirement for predetermining the reliability of POC lactate methods before use present in fetal and perinatal settings.

Procalcitonin as a marker of bacterial infection in children undergoing cardiac surgery with cardiopulmonary bypass.

BACKGROUND: Owing to systemic inflammatory response syndrome, the diagnosis of post-operative infection after cardiopulmonary bypass is difficult to assess in children with the usual clinical and biological tools. Procalcitonin could be informative in this context. METHODS: Retrospective study in a paediatric intensive care unit. Blood samples were collected as soon as infection was clinically suspected and a second assay was performed 24 hours later. Using referenced criteria, children were retrospectively classified into two groups: infected and non-infected. RESULTS: Out of the 95 children included, 14 were infected. Before the third post-operative day, procalcitonin median concentration was significantly higher in the infected group than in the non-infected group - 20.24 nanograms per millilitre with a 25th and 75th interquartile of 15.52-35.71 versus 0.72 nanograms per millilitre with a 25th and 75th interquartile of 0.28 to 5.44 (p = 0.008). The area under the receiver operating characteristic curve was 0.89 with 95% confidence intervals from 0.80 to 0.97. The best cut-off value to differentiate infected children from healthy children was 13 nanograms per millilitre with 100% sensitivity - 95% confidence intervals from 51 to 100 - and 85% specificity - 95% confidence intervals from 72 to 91. After the third post-operative day, procalcitonin was not significantly higher in infected children - 2 nanograms per millilitre with a 25th and 75th interquartile of 0.18 to 12.42 versus 0.37 nanograms per millilitre with a 25th and 75th interquartile of 0.24 to 1.32 (p = 0.26). The area under the receiver operating characteristic curve was 0.62 with 95% confidence intervals from 0.47 to 0.77. A procalcitonin value of 0.38 nanograms per millilitre provided a sensitivity of 70% with 95% confidence intervals from 39 to 89 for a specificity of 52% with 95% confidence intervals from 34 to 68. After the third post-operative day, a second assay at a 24-hour interval can improve the sensitivity of the test. CONCLUSIONS: Procalcitonin seems to be a discriminating marker of bacterial infection during the post-operative days following cardiopulmonary bypass in children.

Silent hypersensitivity to Escherichia coli asparaginase in children with acute lymphoblastic leukemia.

This prospective study aimed to assess the incidence of silent hypersensitivity to Escherichia coli asparaginase in the treatment of acute lymphoblastic leukemia (ALL). Thirty-three children with newly diagnosed ALL were included in the study and treated according to the FRALLE 2000 protocol. The 'A group' (n = 18) differed from the 'B-T group' (n = 15) by a less intensive chemotherapy, the absence of concurrent prednisone therapy, and different asparaginase administration modalities during the second intensification. Asparagine, asparaginase activity, and anti-asparaginase antibodies were measured in each phase before the next injection of asparaginase. Eighteen percent of children presented a silent hypersensitivity. Most of them were in the 'B-T group' (p = 0.07), and maintained low antibody titers throughout the treatment. Clinical hypersensitivity was statistically more frequent in group A (p = 0.002), and allergy occurred mainly during the second intensification when antibody concentrations were significantly increased. We did not find any significant difference between asparaginase activity or asparagine depletion between the silent hypersensitivity and clinical allergy groups. In all, the results of this study suggest that chemotherapy and corticosteroid therapy associated with asparaginase treatment can lower antibody production and contribute to maintaining a silent hypersensitivity state.

Fatal effects of a neonatal high-protein diet in low-birth-weight piglets used as a model of intrauterine growth restriction.

BACKGROUND: Although full-term infants suffering intrauterine growth restriction (IUGR) are routinely fed high-protein (HP) formulas to ensure catch-up growth, the effects of HP intake are poorly understood. An IUGR piglet model provides an opportunity to investigate these effects. METHODS AND RESULTS: Twelve IUGR piglets were artificially fed HP formulas (50% more protein in comparison to sow milk) from the 2nd day of life (d2) until d28. Unexpectedly, all HP piglets developed poor growth, severe hypotonia and polypnea between d10 and d16. One third died spontaneously. This syndrome was investigated to understand its pathophysiology and to adopt a strategy to restore health. Blood and urine biochemistry and amino acid concentrations were investigated in 10 HP piglets and 8 piglets that were fed a normal-protein (NP) formula. In comparison to NP piglets, HP piglets showed significant hypokalemia (2.7 +/- 0.6 vs. 3.6 +/- 0.6 mmol/l; p < 0.01), hypophosphatemia (1.5 +/- 0.2 vs. 3.0 +/- 0.3 mmol/l; p > 0.01), hypercalcemia (3.0 +/- 0.3 vs. 2.5 +/- 0.2 mmol/l; p < 0.01), hyperammonemia (365 +/- 4 vs. 242 +/- 15 micromol/l; p < 0.05), elevated blood urea (6.5 +/- 0.4 vs. 1.3 +/- 0.4 mmol/l; p < 0.01) and elevated taurine concentrations (50.2 +/- 8.5 vs. 17.7 +/- 2.7 micromol/l; p < 0.01). CONCLUSIONS: These altered parameters indicated inadequate potassium and phosphorus dietary supplies in HP piglets. When the HP formula was supplemented with monocalcium phosphate and monopotassium phosphate (HP-sup), serum biochemistry was normalized in piglets fed this formula (n = 8). This experimental strategy restored growth in IUGR piglets fed HP-sup, without a toxic effect. The current findings suggest that use of an HP formula without a proportional increase in its phosphorus and potassium content induces pathology similar to the refeeding syndrome in IUGR piglets.

Impact of changes in serum sodium levels on 2-year neurologic outcomes for very preterm neonates.

OBJECTIVE: The goal was to analyze the relationship between changes in serum sodium levels during the first month of life and impaired functional outcomes at 2 years of age for very preterm infants. METHODS: All very preterm infants who were born at <33 weeks of gestation between January 1, 2003, and July 31, 2004, were hospitalized in the NICU, and survived to discharge were included in this study. Changes in serum sodium levels were measured, and infants were evaluated at corrected age of 2 years. RESULTS: The analysis involved 237 patients, for whom 3927 serum sodium determinations were performed during the first month of life. We defined 3 tertiles of changes in serum sodium levels. A total of 84 infants demonstrated small changes in serum sodium levels (<8 mEq/ L), 86 demonstrated large changes (8 -13 mEq/L), and 67 demonstrated very large changes (13 mEq/L). The reference group was represented by the first tertile. At 2 years of age, large and very large changes in serum sodium levels were significantly associated with risk of impaired functional outcomes, after adjustment for gestational age and perinatal and neonatal hospitalization characteristics (large changes: odds ratio: 3.5 [95% confidence interval: 1.1-11.8]; P = .04; very large changes: odds ratio: 5.1 [95% confidence interval: 1.3-13.6]; P = .02). CONCLUSIONS: Although large and very large changes in serum sodium levels may simply reflect the severity of illness and/or the quality of care, a causal relationship with outcomes cannot be excluded. Cautious fluid and electrolyte management is recommended for very premature infants.

In vivo removal of high- and low-molecular-weight compounds in hemodiafiltration with on-line regeneration of ultrafiltrate.

BACKGROUND: Current methods of renal replacement therapy, combining convection and diffusion, are largely unsatisfactory in removing uremic toxins. Adsorption is a third mechanism that has been applied in extracorporeal therapy. This study evaluates the impact of hemodiafiltration with on-line regeneration of ultrafiltrate, a new two-step integrated sorbent system, on in vivo removal of a wide spectrum of solutes with different molecular weights. METHODS: Pre- and post-dialysis concentrations of small, medium-size, and large molecules were determined in ten patients undergoing regular hemodiafiltration treatments with on-line regeneration of the ultrafiltrate. We also analyzed, at different times of the same dialysis session, the inlet and outlet ultrafiltrate; the latter had been regenerated by the sorbent cartridge and was used as reinfusion liquid. The mean dialysis time was 260 +/- 21.2 min with a blood flow of 361 +/- 33.3 ml/min and a reinjection volume of 3.6 +/- 0.2 l/h. RESULTS: Urea, creatinine and phosphate reduction ratio were respectively 69.8 +/- 8.2, 61.9 +/- 5.5, and 40.2 +/- 17.3%. Removal of medium-size markers such as calcitonin, osteocalcin, beta2-microglobulin, cystatin C, myoglobin and prolactin varied between 24 and 60%. The percentage of reduction for retinol binding protein and alpha1-microglobulin was negligible and we were unable to demonstrate any removal of alpha1-acid glycoprotein, pre-albumin, and albumin in the regenerated ultrafiltrate. CONCLUSION: The hemodiafiltration with on-line regeneration of ultrafiltrate is a new hemodialysis system, which allows uremic toxin removal over a wide molecular-weight spectrum.

Autologous myoblast transplantation after myocardial infarction increases the inducibility of ventricular arrhythmias.

BACKGROUND: Small scale clinical trials suggested the feasibility and the efficacy of autologous myoblast transplantation to improve ventricular function after myocardial infarction. However, these trials were hampered by unexpected episodes of life-threatening ventricular tachyarrhythmias (VT). We investigated cardiac electrical stability after myoblast transplantation to the myocardium. METHODS AND RESULTS: Seven days after coronary ligation, Wistar rats were randomized into 3 groups: a control group receiving no further treatment, a vehicle group injected with culture medium into the infarcted myocardium, and a myoblast group injected with autologous myoblasts. Holter monitoring did not discriminate the myoblast from the vehicle groups. Programmed Electrical Stimulation (PES) was performed to evaluate further a cardiac substrate for arrhythmia susceptibility. The occurrence of sustained VT during PES was similar in control and vehicle groups (5/17 and 4/19 rats, respectively; p=0.50). In contrast, 13/20 rats (65%) from the myoblast group showed at least one episode of sustained VT during PES (p<0.05 and p<0.005 versus control and vehicle groups). As a further control group, rats injected with autologous bone marrow mononuclear cells into the infarcted myocardium did not show increased susceptibility to PES. CONCLUSIONS: In an infarcted rat model, myoblast transplantation but not bone marrow mononuclear cells or myocardial injection per se induces electrical ventricular instability. Because ventricular arrhythmias are life-threatening disorders, we suggest that such preclinical evaluation should be conducted for any new source of cells to be injected into the myocardium.

The effects of milrinone on hemodynamics in an experimental septic shock model.

OBJECTIVE: To investigate the specific hemodynamic effects of the phosphodiesterase inhibitor milrinone in a rabbit model of septic shock in the absence of any other treatment. DESIGN: A prospective, controlled, interventional study. Animal Model: Fourteen sedated New Zealand rabbits. SETTING: Research laboratory of a health sciences university. INTERVENTIONS: Rabbits were anesthetized and vascular catheters inserted in femoral artery and jugular vein. After a stabilization period and the recording of baseline measurements (H0), all animals received a 10-mL infusion of Pseudomonas aeruginosa. Two hours later (H2rabbits were randomly assigned to receive 5% dextrose (control group) or milrinone (milrinone group). MEASUREMENTS AND MAIN RESULTS: Mean arterial blood pressure (MAP) was monitored continuously, and a cardiac index (CI) was determined every 30 mins by a transpulmonary thermodilution technique using an integrated monitoring device (PICCO). No differences were detected between the two groups after stabilization (H0) or before the treatment (H2) for either CI (mL/min(-1)/kg(-1)) or MAP (mm Hg). CI decreased progressively in the control group during the following 4 hrs, but not in the treated group (at H6: 122 +/- 4 vs. 207 +/- 16 mL/min(-1)/kg(-1); p < .05). No drop of MAP occurred after milrinone infusion. A comparison of the treated and control group reveals that milrinone improved tissue perfusion as evidenced by measurements of central venous saturation (at H4: 0.59 +/- 0.05 vs. 0.71 +/- 0.03, p = .04), lactacidemia (at H6: 10.3 +/- 2.4 vs. 3.9 +/- 0.9 mmol/L, p = .03), creatinemia (at H6: 95 +/- 11 vs. 60 +/- 5 micromol/L, p = .02) and survival (at H6: 5 vs. 7, not significant). CONCLUSION: Milrinone improves cardiac output and tissue perfusion in a rabbit model involving severe septic shock.

MODULAR ANALYTICS: A New Approach to Automation in the Clinical Laboratory.

MODULAR ANALYTICS (Roche Diagnostics) (MODULAR ANALYTICS, Elecsys and Cobas Integra are trademarks of a member of the Roche Group) represents a new approach to automation for the clinical chemistry laboratory. It consists of a control unit, a core unit with a bidirectional multitrack rack transportation system, and three distinct kinds of analytical modules: an ISE module, a P800 module (44 photometric tests, throughput of up to 800 tests/h), and a D2400 module (16 photometric tests, throughput up to 2400 tests/h). MODULAR ANALYTICS allows customised configurations for various laboratory workloads. The performance and practicability of MODULAR ANALYTICS were evaluated in an international multicentre study at 16 sites. Studies included precision, accuracy, analytical range, carry-over, and workflow assessment. More than 700 000 results were obtained during the course of the study. Median between-day CVs were typically less than 3% for clinical chemistries and less than 6% for homogeneous immunoassays. Median recoveries for nearly all standardised reference materials were within 5% of assigned values. Method comparisons versus current existing routine instrumentation were clinically acceptable in all cases. During the workflow studies, the work from three to four single workstations was transferred to MODULAR ANALYTICS, which offered over 100 possible methods, with reduction in sample splitting, handling errors, and turnaround time. Typical sample processing time on MODULAR ANALYTICS was less than 30 minutes, an improvement from the current laboratory systems. By combining multiple analytic units in flexible ways, MODULAR ANALYTICS met diverse laboratory needs and offered improvement in workflow over current laboratory situations. It increased overall efficiency while maintaining (or improving) quality.

Bacterial and epidemiologic study of the resistance to oxyiminocephalosporins in Escherichia coli in a French hospital.

OBJECTIVE: To understand the mechanisms and epidemiology of resistance to oxyiminocephalosporins in Escherichia coli over a 2-year period in a French hospital. METHODS: Forty-four strains, resistant or intermediately resistant to one of the oxyiminocephalosporins or aztreonam, were collected from 35 patients. MIC determinations were carried out for the 44 isolates using a panel of beta-lactam antibiotics, and characterization of the beta-lactamases they produced by isoelectric focusing and catalytic activity measurement. Extended-spectrum beta-lactamase production was studied by use of the double disk diffusion test. Conjugation experiments were used to search for plasmidic cephalosporinase. An epidemiologic study was then performed, by use of molecular typing of the strains with an ERIC-PCR method and a case-control analysis. RESULTS: Less than 1% of all the E. coli isolates at our hospital showed decreased susceptibility to oxyiminocephalosporins. Only three of the 44 isolates showed synergy between clavulanate and a third-generation cephalosporin and produced an extended-spectrum beta-lactamase. For the other strains, a beta-lactamase with a highly basic isoelectric point was detected. Spectrophotometric measures confirmed that most of these isolates were AmpC hyper-producers. No plasmidic cephalosporinase could be detected by conjugation experiments. Molecular typing showed all isolates to be different, except for two strains isolated in two patients of the same hospital unit, and for the repeated isolates of some patients. When 20 case patients were compared to 40 randomly selected control patients, prior receipt of an antimicrobial and more specifically of a beta-lactam agent was significantly associated with case patients. CONCLUSIONS: Although it appears to be very rare, the resistance to broad-spectrum cephalosporins needs our attention, because of the high frequency of E. coli infections and beta-lactam use in their treatment.