Detection of SARS-CoV-2 antibodies using commercial assays and seroconversion patterns in hospitalized patients.

OBJECTIVES: SARS-CoV-2 antibody assays are needed for serological surveys and as a complement to molecular tests to confirm COVID-19. However, the kinetics of the humoral response against SARS-CoV-2 remains poorly described and relies on the performance of the different serological tests. METHODS: In this study, we evaluated the performance of six CE-marked point-of-care tests (POC) and three ELISA assays for the diagnosis of COVID-19 by exploring seroconversions in hospitalized patients who tested positive for SARS-CoV-2 RNA. RESULTS: Both the ELISA and POC tests were able to detect SARS-CoV-2 antibodies in at least half of the samples collected seven days or more after the onset of symptoms. After 15 days, the rate of detection rose to over 80% but without reaching 100%, irrespective of the test used. More than 90% of the samples collected after 15 days tested positive using the iSIA and Accu-Tell® POC tests and the ID.Vet IgG ELISA assay. Seroconversion was observed 5 to 12 days after the onset of symptoms. Three assays suffer from a specificity below 90% (EUROIMMUN IgG and IgA, UNscience, Zhuhai Livzon). CONCLUSIONS: The second week of COVID-19 seems to be the best period for assessing the sensitivity of commercial serological assays. To achieve an early diagnosis of COVID-19 based on antibody detection, a dual challenge must be met: the immunodiagnostic window period must be shortened and an optimal specificity must be conserved.

Evolution of coronary artery calcifications following kidney transplantation: relationship with osteoprotegerin levels.

We prospectively assessed the evolution of coronary artery calcification (CAC) and osteoprotegerin (OPG) levels after renal transplantation (RT). Eighty-three recipients were followed-up prospectively during 1 year. Blood was collected before (baseline) and after RT for determination of mineral metabolism parameters including OPG. CAC was measured by multidetector computed tomography at transplantation (baseline) and 1 year later. Progression of CAC was defined as a difference between the follow-up square-root transformed volume (SRV) and the baseline SRV >or= 2.5. By multivariate analysis, baseline OPG level, age and low LDL levels were significantly associated with baseline CAC. RT was accompanied by mineral metabolism improvement with a decrease of OPG from 955 [395-5652] to 527 [217-1818] pg/mL and parathyroid hormone from 94 [1-550] to 62 [16-410] pg/mL. Thirty-one percent of patients did not exhibit CAC at baseline. CAC diminished in 14.5%, stabilized in 59.2% and progressed in 26.3% of patients. Baseline CAC was associated with progression (OR 2.92 [1.02-8.36]). No significant association was found between OPG and CAC progression despite a higher baseline OPG level in progressors (1046 [456-3285]) vs. non-progressors (899 [396-5952] pg/mL). CAC at baseline, but not 1 year after RT, is independently associated with baseline OPG; posttransplant CAC progression is predicted by baseline CAC score.

Protein biochip array technology to monitor rituximab in rheumatoid arthritis.

In rheumatoid arthritis (RA) there are currently no good indicators to predict a clinical response to rituximab. The purpose of this study was to monitor and determine the role of peripheral blood cytokine profiling in differentiating between a good versus poor response to rituximab in RA. Blood samples were collected at baseline and at 3 months from 46 RA patients who were treated with rituximab. Responders are defined by the presence of three of four American College of Rheumatology criteria: >or=20% decrease in C-reactive protein, visual analogical score of disease activity, erythrocyte sedimentation rate and improvement of the disease activity score (28) (four values) by >or=1.2 obtained at 3 months. Twelve cytokines were measured from serum collected on days 0 and 90 by proteomic array, including interleukin-6 (IL-6), tumour necrosis factor-alpha, IL-1a, IL-1b, IL-2, IL-8, interferon-gamma, IL-4, IL-10, monocyte chemoattractant protein-1, epidermal growth factor and vascular growth factor. We showed that C-reactive protein and IL-6 levels decrease significantly at 3 months in the responder group compared with baseline. At day 90 we identified a cytokine profile which differentiates responders and non-responders. High serum levels of two proinflammatory cytokines, monocyte chemoattractant protein-1 and epidermal growth factor, were significantly higher in the responder group at day 90 compared with non-responders. However, we were not able to identify a baseline cytokine profile predictive of a good response at 3 months. These findings suggest that cytokine profiling by proteomic analysis may be a promising tool for monitoring rituximab and may help in the future to identify responder RA patients.

Multi-site, multi-country evaluation of analytical and operational performance of a low-mid volume chemiluminescent immunoassay analyzer.

BACKGROUND: A new automated immunoassay low-mid volume (< or = 250 immunoassays/day) chemiluminescent analyzer, Abbott Architect i1000sR, was evaluated by seven laboratories around the world (4 in Europe, one each in Canada, Japan, and the U.S.A.) to demonstrate equivalent performance for key operating characteristics (e.g., precision, turn around time, limit of detection, functional sensitivity, and linearity). METHODS: The laboratories followed standard protocols to assess precision, limit of detection (LoD), functional sensitivity, assay linearity, method comparison, and sample carryover. Turn around time for three stat assays (beta-hCG, BNP, and CK-MB) and the time required to complete workloads of 50 and 100 tests with a mixture of 75% routine tests and 25% stat tests was also evaluated. RESULTS: Total precision was typically < 5% CV for nine immunoassays. Analytical performance met design goals and demonstrated equivalency to package insert data for assays on market and in use for an existing high volume immunoassay system. Stat turn around times were consistent with the fixed analytical time of 15.6 minutes and met the expectations of the laboratories. Measured test throughput ranged from 47 - 54 tests per hour and demonstrated that the analyzer was fit for the intended purpose of supporting a laboratory that performs < or = 250 immunoassays per day. CONCLUSIONS: A multisite, international analyzer familiarization study is a practical means of confirming that a new instrument meets both a manufacturer's design specifications and users' real world expectations and provides a pragmatic test for the system. The experience of investigators at seven sites around the world indicates that a new fully automated chemiluminescent system is suitable for use.

[Carbonyl stress and oxidatively modified proteins in chronic renal failure]. / Stress carbonylé et modifications oxydatives des protéines au cours de l'insuffisance rénale chronique.

Oxidative stress is commonly observed in chronic renal failure patients resulting from an unbalance between overproduction of reactive oxygen species and impairement of defense mechanisms. Proteins appear as potential targets of uremia-induced oxidative stress and may undergo qualitative modifications. Proteins could be directly modified by reactive oxygen species which leads to amino acid oxydation and cross-linking. Proteins could be indirectly modified by reactive carbonyl compounds produced by glycoxidation and lipo-peroxidation. The resulting post-traductional modifications are known as carbonyl stress. In addition, thiols could be oxidized or could react with homocystein leading to homocysteinylation. Finally, tyrosin could be oxidized by myeloperoxidase leading to advanced oxidative protein products (AOPP). Oxidatively modified proteins are increased in chronic renal failure patients and may contribute to exacerbate the oxidative stress/inflammation syndrome. They have been involved in long term complications of uremia such as amyloidosis and accelerated atherosclerosis.

Improved quality of samples and laboratory turnaround time using 3.5 mL low vacuum BD Vacutainer® Barricor tubes in the emergency department.

BACKGROUND: Centrifugation is a consuming time step which participates to increase the turnaround time (TAT) in laboratories, likewise hemolysis sample that needs a re-sampling could delay management of patients. Recently, it has been postulated that BD Barricor™ tube could allow to decrease the centrifugation time and prevent hemolysis, two key feature to ensure high-quality results.Aim of the study was to evaluate the impact of replacing 4 mL BD vacutainer heparin lithium tube by low vacuum 3.5 mL BD vacutainer Barricor™ tube in an emergency department (ED) on hemolysis rate and TAT. METHODS: Data of hemolysis index (HI) and TAT were compared between the first period of 15 days using 4 mL BD vacutainer heparin lithium tubes with 15 min at 2000xg as centrifugation setting and a second period of 15 days using BD vacutainer Barricor™ tube centrifuged 3 min at 4000xg. RESULTS: A significantly reduced time duration between reception of sample and available results in informatics lab system was observed with the reduction time of centrifugation allowed by use of Barricor™ tube compared to regular heparin lithium tubes (p < 0.001). A significative decrease in hemolysis rate also occurred in the second period as samples with HI < 10 reached from 52.5% in the first period to 68.5% (p < 0.001) in the second. CONCLUSION: Low vacuum BarricorTM tubes allowing a higher speed of centrifugation improve lab TAT without impairment of sample quality as a significant reduction of hemolysis was observed, a double advantage which is of particular interest for ED.

Protein biochip array technology for cytokine profiling predicts etanercept responsiveness in rheumatoid arthritis.

In rheumatoid arthritis (RA) there are currently no useful indicators to predict a clinical response to tumour necrosis factor-alpha (TNF-alpha) blockade. The purpose of this study was to determine the role of peripheral blood cytokine profiling in differentiating between a good versus poor response to etanercept in RA. Peripheral blood samples were collected at baseline and at 3 months from 33 patients with active disease who were treated twice weekly by etanercept therapy. Responders are defined by the presence of three of four American College of Rheumatology criteria: > or =20% decrease in C-reactive protein (CRP), visual analogue score of disease activity, erythrocyte sedimentation rate and improvement of the disease activity score (28; four values) by > or =1.2 obtained at 3 months. Twelve cytokines were measured from serum collected on days 0 and 90 by proteomic array (protein biochip array, Investigator Evidence, Randox France), including interleukin (IL)-6, TNF-alpha, IL-1a, IL-1b, IL-2, IL-8, interferon-gamma, IL-4, IL-10, monocyte chemoattractant protein (MCP)-1, epidermal growth factor (EGF) and vascular endothelium growth factor. Our results showed that high serum levels of MCP-1 and EGF were associated with a response to etanercept. In addition, the increase of two combined parameters CRP and EGF was predictive of a response to etanercept treatment at 3 months (sensitivity: 87.5% and specificity: 75%, accuracy: 84.4%). These findings suggest that cytokine profiling by proteomic analysis before treatment initiation may help to identify a responder patient to TNF-alpha blocking agents in RA.

Training-induced improvement in lipid oxidation in type 2 diabetes mellitus is related to alterations in muscle mitochondrial activity. Effect of endurance training in type 2 diabetes.

AIM: We investigated whether or not, in type 2 diabetic (T2D) patients, an individualized training effect on whole-body lipid oxidation would be associated with changes in muscle oxidative capacity. METHODS: Eleven T2D patients participated in the study. Whole-body lipid oxidation during exercise was assessed by indirect calorimetry during graded exercise. Blood samples for measuring blood glucose and free fatty acids during exercise, and muscle oxidative capacity measured from skeletal muscle biopsy (mitochondrial respiration and citrate synthase activity), were investigated in the patients before and after a 10-week individualized training program targeted at LIPOXmax, corresponding to the power at which the highest rate of lipids is oxidized (lipid oxidation at LIPOXmax). RESULTS: Training induced both a shift to a higher-power intensity of LIPOXmax (+9.1+/-4.2W; P<0.05) and an improvement of lipid oxidation at LIPOXmax (+51.27+/-17.93 mg min(-1); P<0.05). The improvement in lipid oxidation was correlated with training-induced improvement in mitochondrial respiration (r=0.78; P<0.01) and citrate synthase activity (r=0.63; P<0.05). CONCLUSION: This study shows that a moderate training protocol targeted at the LIPOXmax in T2D patients improves their ability to oxidize lipids during exercise, and that this improvement is associated with enhanced muscle oxidative capacity.

Waist circumference adds to the variance in plasma C-reactive protein levels in elderly patients with metabolic syndrome.

BACKGROUND: C-reactive protein (CRP), a nonspecific marker of the inflammatory status, is associated with cardiovascular disease risk factors and may be an important feature of the metabolic syndrome (MSX) in middle-aged subjects. OBJECTIVES: We assessed the relationship of CRP levels to specific components of MSX and other potential determinants in apparently healthy elderly subjects living in the South of France. METHODS: In the framework of the population-based POLA (Pathologies Oculaires Liées à l'Age) Study, performed in 2,404 subjects aged 60 years or more, we measured the plasma CRP levels. All subjects with known systemic inflammatory diseases, such as chronic bronchitis, cardiovascular disease, and diabetes, and those who were on systemic steroid therapy as well as subjects with CRP levels >10 mg/l were excluded from the study, leaving 1,709 subjects for the statistical analyses. MSX was defined according to NCEP (National Cholesterol Education Program) criteria. Other potential determinants were assessed through interviewer-based questionnaire. RESULTS: We grouped the subjects into three categories based on the 75th and 25th percentiles, corresponding to 3.05 and 0.82, respectively. We compared subjects in the highest quartile, i.e., with CRP >/=3.05 mg/l, with those in the two intermediate quartiles, i.e., with 0.82 < CRP < 3.05, and those in the lowest quartile, i.e., with CRP <0.82 mg/l according to gender. MSX, which had a prevalence of 31%, was significantly associated with elevated CRP levels. Among MSX components, the strongest positive association with the highest quartile of CRP was with waist circumference in males as well as in females (age-adjusted odds ratio OR 3.06 and 95% confidence interval CI 1.82-5.14; OR 7.04 and 95% CI 4.79-10.34, respectively). Each component of the MSX, such as abnormal fasting plasma glucose (OR 2.90, 95% CI 1.69-4.99), triglycerides (OR 1.96, 95% CI 1.30-2.96), high-density lipoprotein cholesterol (OR 2.31, 95% CI 1.61-3.30), and blood pressure (OR 1.66, 95% CI 1.12-2.45), was significantly associated with high CRP values in elderly women only. In men, only current smoking was significantly associated with high CRP levels (OR 1.52, 95% CI 1.04-2.2). In multivariate analysis, the waist circumference remained significantly associated with high CRP levels, with a graded effect of CRP quartile whatever the gender. In men, current and former smoking remained significantly associated with the CRP levels. In women, the association observed in univariate analysis with fasting glucose or hypertension did not reach statistical significance in the multivariate analysis, while only a weak association could be observed with lipid parameters such as triglycerides and high-density lipoprotein cholesterol. CONCLUSIONS: Abdominal adiposity adds to the variance in plasma CRP levels in elderly patients with MSX. This suggests that weight loss or other interventions targeted at adipocyte-related inflammation may represent an important means to prevent subclinical inflammation in the elderly, bearing a high risk of cardiovascular disease.

Evaluation of a capillary zone electrophoresis system versus a conventional agarose gel system for routine serum protein separation and monoclonal component typing.

Capillary zone electrophoresis of serum proteins is increasingly gaining impact in clinical laboratories. During 2003, we compared the fully automated capillary electrophoresis (CE) system from Beckman (Paragon CZE 2000) with the method agarose gel electrophoresis Sebia (Hydrasis-Hyris, AGE). This new study focused on the evaluation of analytical performance and a comparison including 115 fresh routine samples (group A) and a series of 97 frozen pathologic sera with suspicion of monoclonal protein (group B). Coefficients of variation (CVs %) for the five classical protein fractions have been reported to be consistenly < 9% in within-run and < 10% in between-run imprecision studies with the Paragon 2000 system. The results of the comparison study (group A) demonstrated a good correlation between the CE system and AGE, except for beta-globulin (r = 0.65). Among the 97 pathologic serum samples (group B), there were 90 in which we detected a monoclonal protein by immunofixation (IF) (immunosubtraction (IS) was not used). AGE and Paragon 2000 failed to detect 7 and 12 monoclonal proteins, respectively, leading to a concordance to 92% for AGE and 87% for Paragon 2000 for identifying electrophoretic abnormalities in this group. Beta-globulin abnormalities and M paraprotein were well detected with Paragon 2000. Only 81% (21 vs 26) of the gammopathies were immunotyped with IS by two readers blinded to the IF immunotype. The Paragon 2000 is a reliable alternative to conventional agarose gel electrophoresis combining the advantages of full automation (rapidity, ease of use and cost) with high analytical performance. Qualified interpretation of results requires an adaptation period which could further improve concordance between the methods. Recently, this CE system has been improved by the manufacturer (Beckman) concerning the migration buffer and detection of beta-globulin abnormalities.

Small dense low-density lipoprotein in renal transplant recipients: a potential target for prevention of cardiovascular complications?

BACKGROUND: Immunosuppressive therapy is frequently associated with dyslipidemia, which is involved in cardiovascular morbidity and mortality in transplant patients. Beyond classical factors, such as low-density lipoprotein (LDL) cholesterol (LDL-C), qualitative abnormalities of lipoproteins, such as presence of the atherogenic factor, small dense LDL, may be of interest for a cardiovascular risk assessment. This study was designed to explore LDL size in renal transplant recipients in relation to quantitative lipid parameters and apolipoprotein (apo) CIII polymorphism. METHODS: Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), LDL-C, apoA1, apoB, apoCIII, and LDL size were measured in 62 patients of mean age 45 +/- 13 years including 71% men at 2 +/- 0.5 years after renal transplantation. Thirty-two patients received cyclosporine (CsA), while 30 received tacrolimus (FK). ApoCIII Sstl genotype was determined by restriction fragment length polymorphism. RESULTS: The CsA group exhibited higher TC (P = .001), LDL-C (P = .004), non-HDL-C (P = .009), HDL-C (P = .03), apoB (P = .008), and apoCIII (P = .002) levels than the FK group. However, LDL-C (CsA: 3.7 +/- 1.2, FK: 3.0 +/- 0.6 mmol/L) and triglyceride levels (CsA: 1.55 mmol/L, FK: 1.37 mmol/L) were near the normal range in both groups. Allelic frequency of the sparse A2 allele associated with hypertriglyceridemia was 6%, similar to the general population. LDL size, which was comparable in the CsA and FK groups (25.87 +/- 0.89 vs 25.75 +/- 0.62 nm, respectively), inversely correlated with TG/HDL ratio (P = 10(-4)). Prevalence of small dense LDL (defined as <25.5 nm) was 26% in the CsA group and 33% in the FK group. CONCLUSION: After LDL-C goal has been achieved, LDL size modulation may be taken into account in order to prevent cardiovascular complications.

Renal transplantation decreases osteoprotegerin levels.

Vascular calcifications are an important risk factor for cardiovascular mortality and morbidity in patients with chronic renal failure. Osteoprotegerin, a soluble decoy receptor for receptor activator NFkB ligand, has emerged as an independent predictive factor of atherosclerosis and vascular calcification in hemodialysis patients. Sparse data are available on the evolution of osteoprotegerin after renal transplantation. The aim of this study was to follow the evolution of serum osteoprotegerin levels and biochemical risk factors after renal transplantation. Forty patients were included. Blood samples for analysis were collected before and 3 months after renal transplantation. Besides the expected diminution in calcium-phosphate product, we have shown an early normalization of osteoprotegerin (10.05 +/- 4.77 pmol/L to 4.59 +/- 2.26 pmol/L). This study demonstrates that kidney transplantation improves this risk factor for vascular calcifications. However, these preliminary results should be confirmed and extended by the follow-up of vascular calcifications in the long term.

Evaluation of an immunoassay (Abbott-IMX Analyzer) allowing routine determination of sirolimus: comparison with LC-MS method.

BACKGROUND: The use of the immunosuppressive agent sirolimus is increasing in renal transplantation but its monitoring often requires high-performance liquid chromatography (HPLC) with ultra-violet (UV) or tandem mass spectrometric (MS-MS) detection. The aim of this study was to compare a new microparticle enzyme immunoassay (MEIA, Microparticle Enzyme Immunoassay) on IMx Abbott Analyser with a liquid chromatography-mass spectometry (LC-MS) method. METHOD: The accuracy of immunoassay analytical performance including within run and between run imprecision and linearity was tested. For comparison studies, sirolimus level was then determined with the two methods on 98 samples from 52 transplant patients. RESULTS: Total intra-assay and inter-assay variation coefficients were below 10% at the three levels tested, and the coefficient of linearity was r = 0.99. The values obtained were highly correlated with the LC-MS method (MEIA = 1.02LC-MS + 0.91; r(2) = 0.87). As a result, the immunoassay showed good performance, and clinical sample measurements were not affected by the method. The MEIA may be a useful alternative for routine monitoring of sirolimus.

The role of mineral metabolism and inflammation on dialysis vascular access failure.

Thrombosis of arteriovenous fistula (AVF) is the leading cause of vascular access (VA) loss usually due to silent stenosis. Therefore, assessment of relevant risk factors of VA monitoring may provide insight into potential therapeutic targets for stenosis and thrombosis. The aim of this study was to evaluate the influence of cardiovascular risk factors (including inflammation and mineral metabolism dysfunctions) on the failure of internal AVF in HD patients. 128 HD patients with internal AVF were included in the study and followed up for two years. At baseline, VA morphology and function were followed by Doppler ultrasonography and serum albumin, prealbumine, C-reactive protein, orosomucoid, calcium, phosphorus, parathyroid hormone, bone-type alkaline phosphatase, osteoprotegerin and receptor activator of nuclear factor ê ê B ligand were measured. At baseline, 50 stenoses were detected but none of them required any intervention. Age and biological parameters did not significantly differ between patients with or without VA stenosis. Over the two year- follow up, VA thrombosis occurred in 19 patients. Preexisting stenosis of VA was present in 9/19 patients (47.3% of cases) (chi-square = 3.708, p = 0.0538). Despite the low rate of events, phosphorus [1.75 (0.95-2.77) vs 1.42 (0.47-3.22) mmol/L, p = 0.0416], Calcium x Phosphorus product [4.00 (2.00-5.90) vs 3.40 (1.10-6.80) mmol(2)/L(2), p = 0.0676] and parathyroid hormone [165.00 (1.00-944.00) vs 79.50 (1.00-846.60) ng/L, p = 0.0814) levels were higher in the 19 thrombotic patients whereas all other biological parameters did not significantly differ. These results, which confirm that VA thrombosis occurs more frequently upon preexisting stenosis, also demonstrate that mineral metabolism disorders, compared to inflammation, may contribute to VA dysfunction leading to thrombosis.

Monthly reference change value of cardiac troponin in hemodialysis patients as a useful tool for long-term cardiovascular management.

PURPOSE OF RESEARCH: Circulating cardiac troponin (cTn) has been identified as a risk factor for cardiovascular and overall mortality in patients undergoing hemodialysis. However, its interpretation remains difficult due to the high prevalence of patients with cTn level beyond the 99th percentile. Determining the cTn reference change value (RCV) may help in assessing a clinically significant change of cTn during regular follow-up of patients. We aimed to determine the long-term RCV of cTn in such patients and to calculate the perdialytic reduction rate of cTn. DESIGN AND METHODS: To calculate RCV, high-sensitivity (hs)-cTnT (Roche), hs-cTnI (Abbott), and cTnI-ultra (Siemens) were determined every month before the midweek dialysis session over a 3-month period in 36 stable hemodialysis patients. cTn was also measured after the midweek dialysis session to calculate the cTn removal rate. RESULTS: The mean RCV (95% confidence interval) was 22% (18-26) for hs-cTnT versus 53% (34-73) for hs-cTnI versus 65% (45-84) for cTnI-ultra. Log-normal RCV (%) was -19/+25 for hs-cTnT, -33/+96 for hs-cTnI, and -39/+115 for cTnI-ultra. The index of individuality was <0.6 regardless of the cTn assay used. A significantly greater reduction rate was observed for hs-cTnT (48%) than for hs-cTnI (30%, p<0.001) and cTnI-ultra (29%, p<0.05). CONCLUSIONS: These results underline the need to use the RCV approach rather than cutoff points to identify the critical change in long-term serial cTn levels. In addition, RCV should be determined for each available assay due to significant differences between assays. Removal of cTn during hemodialysis sessions should also be considered if acute coronary syndrome is suspected during a session.

Biological and psychological predictors of posttraumatic stress disorder onset and chronicity. A one-year prospective study.

BACKGROUND: Few studies have prospectively examined risk factors for posttraumatic stress disorder (PTSD) in the aftermath of a traumatic exposure. The aim of this study is to identify the concurrent influence of psychological and biological diatheses on PTSD onset and maintenance, taking into account socio-demographic factors and psychiatric antecedents. METHODS: A total of 123 civilians (61.8% of women) recruited in emergency units, were assessed using validated instruments during the first week and then at 1, 4, and 12 months post-trauma. Baseline assessment included evaluation of the psychological diathesis (i.e. psychiatric history and peritraumatic distress and dissociation), and the biological diathesis [i.e. cortisol, norepinephrine, epinephrine, c-reactive protein, total cholesterol, HDL cholesterol, glycosylated haemoglobin, waist-to-hip ratio (WHR), body mass index, diastolic and systolic blood pressure (SBP), and heart rate]. RESULTS: Multivariate logistic regression analyses demonstrated both psychological and biological diatheses to be independent risk factors for PTSD. Peritraumatic distress and dissociation predicted onset (1-month) and mid-term PTSD (4-months), respectively. PTSD risk was associated positively with SBP and negatively with WHR, throughout the follow-up. In addition, a higher level of 12 h-overnight urinary norepinephrine independently predicted mid-term PTSD (4-months). CONCLUSIONS: This prospective study shows that peritraumatic psychological and biological markers are independent predictors of PTSD onset with specificities according to the stage of PTSD development; the psychological diathesis, i.e. peritraumatic distress and dissociation, being a better predictor of short-term dysfunction whereas biological diathesis was also predictive of development and maintenance of PTSD.

Immunonephelometric determination of fibrinogen on citrated or heparinized plasma: comparison with functional Clauss method.

BACKGROUND: Fibrinogen is routinely determined by functional assay on citrated plasma in the hematology department. However, immunoassay can be performed easily with nephelometric analyzer in the clinical chemistry laboratory allowing automatization. The aim of this study was first to compare the clotting von Clauss method (activity assay) with an immunonephelometric method (antigen assay) on the BN ProSpec (Dade Behring). Moreover, we evaluated the possibility of collecting blood samples on heparin to facilitate blood collection for clinicians and reduce required blood collection volumes for dosages. METHODS: In a first step of experiment, the accuracy of immunonephelometric analytical performance was tested on heparinized and citrated tubes. For comparison studies, fibrinogen activity was then determined on citrated tubes in the hematology department and antigen measurement was performed on both citrated and heparinized plasma from 130 consecutive patients. RESULTS: As a result, the immunonephelometric method shows reliable performance and clinical sample measurements are not affected by the method used, validating the use of heparinized plasma samples for fibrinogen antigen determination with Dade Behring reagents.

Preliminary evaluation of a new chemiluminescence assay (Liaison Cyclosporine; DiaSorin Laboratories) allowing both C0 and C2 cyclosporine levels determination: comparison with RIA method.

Cyclosporine (CsA) monitoring is generally assessed by trough concentration determinations (C0). Recently, the 2-hour postdose CsA level (C2) has been proposed to be a better measurement to predict graft outcome and prevent toxicity. However, using the available methods, C2 determinations require external dilution, which impairs the precision and practicability of the assay. This study assessed the performance characteristics of a new competitive chemiluminescence immunoassay (CLIA, DiaSorin Laboratories, Anthony, France) for the determination of both C0 and C2 CsA concentrations in whole blood on a Liaison analyzer. The results were compared with the RIA method (DiaSorin) used in our laboratory as a reference technique. Analytical performances showed that the total intra-assay variation coefficients (CVs) on the CLIA Liaison ranged from 7.6% to 11.3%, while the between-day imprecision was 11% (15.2%, 11.5%, and 6.5%). The linearity of the method was estimated over the range of 30 to 2400 ng/mL as a correlation coefficient of r = .997. Recoveries, which were checked by adding pure CsA to CsA-free blood, showed a mean value of 86%. A total of 236 whole-blood samples (31% women, 69% men of mean age 45 +/- 17 years) were subjected to a comparative study of CLIA-CsA versus RIA (radioimmunoassay) values, yielding a correlation coefficient >0.90 (CLIA = 0.825RIA+21.611; r(2) > .90). In conclusion, the CLIA Liaison CsA kit represents an alternative to the radioisotopic method, which allows both C0 and C2 determinations without any preanalytical step. The chemiluminescence method demonstrated good analytical performance and practicability in routine use.

The V-twin system (Dade Behring Laboratories): a useful tool for immunosuppressive drug monitoring.

The predose trough cyclosporine (CsA) level (C0) was widely used to assess the possibility of drug nephrotoxicity. Owing to its potential limitation as an indicator of total drug exposure, 2-hour postdose (C2) monitoring has been considered to be a more accurate marker. The V-Twin analyzer (Vital SC, Netherlands) conceived for EMIT technologies (Dade Behring Laboratories) is proposed herein to determine CsA levels using a specific calibrator without any dilution, as well as tacrolimus (FK) and mycophenolate mofetil (MMF) levels. Both CsA (C0: n = 133 and C2: n = 55) and FK (n = 121) EMIT assays were compared to the RIA CsA assay (DiaSorin Laboratory) and to the MEIA tacrolimus assay (Abbott Laboratory), respectively. In addition, the feasibility of MMF EMIT assay was evaluated. Overall, 309 transplant patients were included in this study. For all parameters tested, total imprecision studies were lower than 10%, and the coefficient of linearity was r(2) > .99. For the CsA kit, the range of linearity was between 25 and 500 ng/mL for the C0 and 400 and 2000 ng/mL for the C2 assay. The values obtained were highly correlated with the RIA for the C0 levels (EMIT = 0.9 RIA+3.66; r = .97) and for the C2 levels (EMIT = 0.89 RIA-14.2; r = .956). Similar results were obtained with the EK EMIT kit, with a linearity range between 3 and 30 ng/mL, and a high concordance with the MEIA test (EMIT = 0.98 RIA+1.09; r = .96). Preliminary MMF results in 59 sera, containing from 0.1 to 30 microg/mL, showed that this examination could be included as a routine. The V-twin system is a useful tool for routine monitoring with a single method for C0 and C2 cyclosporine, tacrolimus, and mycophenolate levels.

High prevalence of small dense LDL as an underestimated component of heart transplantation-induced dyslipidemia: potential role in graft coronary vasculopathy?

Heart transplantation-induced dyslipidemia is a recognized risk factor for cardiac allograft vasculopathy that affects survival prognosis. Beyond increased lipids, low-density lipoprotein (LDL) size and systemic factors, including glucose intolerance, oxidative stress, and inflammation, must be taken into account as components of the atherosclerotic risk. The aim of this study was to explore the atherogenic profile of heart transplant recipients (HTR) by assessing lipid parameters, glycemia, oxidative stress status, and inflammation in 59 transplant patients (follow-up of 6 +/- 3 years) compared to 20 healthy volunteers. Classical hypercholesterolemia and hypertriglyceridemia were observed in HTR compared to controls, associated with increased apoCIII levels (0.13 +/- 0.6 vs 0.07 +/- 0.03 g/L, P < .01). Mean LDL size was reduced in HTR compared to controls (25.22 +/- 0.72 vs 26.06 +/- 0.54 nm, P < .001) with an abnormally high prevalence (69% vs 0%, P < .001) of small dense LDL (<25.5 nm). Hyperglycemia (7.3 +/- 3 vs 5.4 +/- 0.8 mmol/L, P < .05) and inflammation (high-sensitive CRP: 3.1 +/- 3 vs 1.6 +/- 0.9 mg/L, P < .001) were evidenced in HTR since no difference in oxidative stress parameters was observed. In conclusion, a high prevalence of small dense LDL is an important component of posttransplantation dyslipidemia.