Analytical performance of the VITROS® Immunodiagnostic Products total PSA II and free PSA assays.

OBJECTIVES: To assess the precision and the performance of the VITROS(®) total PSA II (tPSA) and free PSA (fPSA) assays on the VITROS(®) ECi/ECiQ Immunodiagnostic system. DESIGN AND METHODS: The precision of the tPSA and fPSA assays was evaluated following the Clinical and Laboratory Standards Institute (CLSI)-guideline EP5-A2. During a 20-day period, 2 runs of 5 quality control (QC) samples were performed daily. Results of tPSA (n=292) and fPSA (n=289) were compared between VITROS(®) ECi/ECiQ Immunodiagnostic system and Roche Cobas 8000 e602 system (Cobas tPSA and fPSA assays). A modified CLSI-guideline EP9-A2 was used to correlate the results based on a Deming regression correlation study. RESULTS: A within-run and within-calibration imprecision of ≤2% was obtained for all 5 QC concentration levels for both tPSA and fPSA. Method comparison revealed a constant bias of 17% for tPSA and 6% for fPSA. These values are within the desirable bias of 18.7% suggested by the Westgard Biological Variation Database Specifications. A high agreement was found between the two methods, with correlation coefficients of 0.997 and 0.993 for tPSA and fPSA respectively. CONCLUSION: The VITROS(®) tPSA and fPSA assays showed an excellent precision and bias and a good correlation with the Roche method.

Depressive symptoms in Crohn's disease: relationship with immune activation and tryptophan availability.

Crohn's disease (CD) is associated with immune activation and depressive symptoms. This study determines the impact of anti-tumor necrosis factor (TNF)-α treatment in CD patients on depressive symptoms and the degree to which tryptophan (TRP) availability and immune markers mediate this effect. Fifteen patients with CD, eligible for anti-TNF-α treatment were recruited. Disease activity (Harvey-Bradshaw Index (HBI), Crohn's Disease Activity Index (CDAI)), fatigue (Multidimensional Fatigue Inventory (MFI)), quality of life (Inflammatory Bowel Disease Questionnaire (IBDQ)), symptoms of depression and anxiety (Symptom Checklist (SCL-90), Beck Depression Inventory (BDI), Hamilton Depression Rating Scale (HDRS)), immune activation (acute phase proteins (APP)), zinc and TRP availability were assessed before treatment and after 2, 4 and 8 weeks. Anti-TNF-α increased IBDQ scores and reduced all depression scores; however only SCL-90 depression scores remained decreased after correction for HBI. Positive APPs decreased, while negative APPs increased after treatment. After correction for HBI, both level and percentage of γ fraction were associated with SCL-90 depression scores over time. After correction for HBI, patients with current/past depressive disorder displayed higher levels of positive APPs and lower levels of negative APPs and zinc. TRP availability remained invariant over time and there was no association between SCL-90 depression scores and TRP availability. Inflammatory reactions in CD are more evident in patients with comorbid depression, regardless of disease activity. Anti-TNF-α treatment in CD reduces depressive symptoms, in part independently of disease activity; there was no evidence that this effect was mediated by immune-induced changes in TRP availability.

Laboratory detection of macro-aspartate aminotransferase: case report and evaluation of the PEG-precipitation method.

BACKGROUND: Chronic elevated AST without other signs of liver disease, cardiac or skeletal abnormalities, is suggestive for macro-AST. Laboratory detection can be performed by gel filtration chromatography, ultrafiltration or precipitation with polyethylene glycol (PEG). PATIENT AND METHODS: A healthy 27 year-old female was referred because of chronic elevated AST (116-704U/L) without other abnormalities. Macro-AST positivity was suspected since AST was no longer measurable in the supernatant of a serum sample (<3U/L) after PEG precipitation. Optimization of this method included analysis of proteins and lipids precipitated, testing the effect of different PEG concentrations and centrifugation times. 25% (m/v) PEG solution gave the most reliable results. No significant difference was seen between 10 and 30 min centrifugation time. A reference range was obtained by analysis of 31 normal patient samples (mean % PEG precipitation activity 35.1% with 95% confidence limits of 14.5-62.5%). Retrospective analysis of 1371 patient samples with elevated AST revealed one other positive patient sample. CONCLUSION: Early recognition of macro-AST, proven by simple PEG precipitation, can avoid time-consuming and invasive investigations.

Influence of separator gel in Sarstedt S-Monovette® serum tubes on various therapeutic drugs, hormones, and proteins.

BACKGROUND: A separator or barrier gel is a common component of serum and plasma collection tubes. Despite their advantages, the use of these tubes is not universally accepted, especially for therapeutic drug monitoring (TDM). The aim of this study was to evaluate whether the polyacrylester separator gel in Sarstedt S-Monovette\® tubes influences the concentration of 10 selected parameters (amikacin, vancomycin, valproic acid, acetaminophen, cortisol, free thyroxine, thyroid-stimulating hormone, transferrin, prealbumin and carcinoembryonic antigen) in a clinically significant way. METHODS: Results from patient samples collected in plastic Sarstedt S-Monovette® tubes with separator gel were compared with those from plain serum sample tubes. Analytes were measured in both tubes on 4 consecutive days to study the influence of prolonged contact with the separator gel. Between analyses tubes were stored at 4°C. Stability was also evaluated over 72 h for each collection tube. When statistical differences were detected, the clinical significance was evaluated based on the total allowable error (TEa). RESULTS: On day 1 no statistically significant differences were observed between samples collected in Sarstedt S-Monovette® tubes with and without separator gel. Statistical differences were present from day 2 on, but were not clinically significant. All evaluated parameters were clinically stable over 72 h at 4°C based on TEa, except for transferrin en fT4. CONCLUSION: The separator gel in Sarstedt S-Monovette® tubes did not show statistically significant differences on the day of phlebotomy. Later on statistically significant differences appeared but except for the stability of fT4 and transferrin they all remained clinically insignificant.

Biochemical markers for blood-brain barrier dysfunction in acute ischemic stroke correlate with evolution and outcome.

BACKGROUND/AIMS: We evaluated the cerebrospinal fluid/serum albumin ratio (AR) and kinetics of matrix metalloproteinase-9 (MMP-9) in blood as markers for blood-brain barrier (BBB) disruption after acute ischemic stroke. METHODS: The AR was determined in 88 patients with acute ischemic stroke or transient ischemic attack. MMP-9 was measured on admission, 24, 72 h and 7 days after stroke onset. RESULTS: The AR was related to stroke severity, the occurrence of stroke progression and the modified Rankin Scale score at month 3. MMP-9 levels on admission were significantly elevated compared to controls and dropped in the first 72 h after stroke, except in patients with stroke progression and larger infarcts in the subacute phase. CONCLUSIONS: We demonstrate that the extent of BBB breakdown in hyperacute stroke relates to initial stroke severity, stroke evolution and long-term outcome. The kinetics of MMP-9 confirm its pivotal role in secondary brain damage after ischemic stroke.

Serum testosterone concentration in male autistic youngsters.

OBJECTIVE: Research on the biological pathophysiology of autism has found some evidence that alterations in androgenic hormones may play a role in the pathophysiology of that disorder. We studied morning concentrations of serum testosterone in a very homogenic group of postpubertal youngsters with autism and a group of normal controls. METHODS: This study examines the serum testosterone concentration on 9 consecutive time points between 08.00 AM and 12.00 AM in 18 high- functioning male youngsters with autism (age 12-18) and 22 healthy volunteers participated in this study. All subjects passed the onset of puberty (Tanner-stage III-IV) and were of the Caucasian race. RESULTS: Repeated measures ANOVA revealed a significant time effect, with a decline in the testosterone concentration during the test and time X diagnosis interaction.The total testosterone concentration was significantly lower in the autism group compared to the group of normal controls. CONCLUSIONS: The significant decrease in serum testosterone concentration in male youngsters with autism suggest that the turnover of testosterone may take part in the pathophysiology of autism. Suggestions for further research are discussed.

The role of tryptophan catabolism along the kynurenine pathway in acute ischemic stroke.

Post-stroke inflammation may induce upregulation of the kynurenine (KYN) pathway for tryptophan (TRP) oxidation, resulting in neuroprotective (kynurenic acid, KA) and neurotoxic metabolites (3-hydroxyanthranillic acid, 3-HAA). We investigated whether activity of the kynurenine pathway in acute ischemic stroke is related to initial stroke severity, long-term stroke outcome and the ischemia-induced inflammatory response. Plasma concentrations of TRP and its metabolites were measured in 149 stroke patients at admission, at 24 h, at 72 h and at day 7 after stroke onset. We evaluated the relation between the KYN/TRP ratio, the KA/3-HAA ratio and stroke severity, outcome and inflammatory parameters (C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and neutrophil/lymphocyte ratio (NLR)). KYN/TRP but not KA/3-HAA correlated with the NIHSS score and with the infarct volume. Patients with poor outcome had higher mean KYN/TRP ratios than patients with more favourable outcome. The KYN/TRP ratio at admission correlated with CRP levels, ESR and NLR. The activity of the kynurenine pathway for tryptophan degradation in acute ischemic stroke correlates with stroke severity and long-term stroke outcome. Tryptophan oxidation is related to the stroke-induced inflammatory response.

Decrease in uric acid in acute ischemic stroke correlates with stroke severity, evolution and outcome.

BACKGROUND: Although uric acid (UA) is one of the most important antioxidants in plasma and appears to be neuroprotective in animal models, results from human studies are controversial. In this study, we investigated the kinetics of serum UA concentrations in the acute, subacute and chronic phase of ischemic stroke and its relation with initial stroke severity, stroke evolution in the subacute phase and long-term stroke outcome. METHODS: Serum concentrations of UA were measured in 199 stroke patients at admission (median, 2.8 h after stroke onset), at 24 h, 72 h, day 7, month 1 and month 3 after onset of stroke. We evaluated the relationship between changes in UA concentrations and (a) stroke severity [patients with transient ischemic attack (TIA) vs. stroke patients, National Institutes of Health Stroke Scale (NIHSS) score at admission], (b) stroke evolution (stroke progression, infarct volume at 72 h), and (c) stroke outcome [modified Rankin scale (mRS) score at month 3, mortality]. RESULTS: UA concentrations decreased significantly during the first 7 days after stroke onset before returning to baseline (p < 0.001). Mean plasma UA concentrations decreased from 336.66 +/- 113.01 micromol/L at admission to 300.37 +/- 110.04 micromol/L at day 7 (p < 0.001) in patients with stroke, but did not change significantly in patients with TIA. Changes in UA concentrations from admission to day 7 (DeltaUA(day 7)) correlated with the NIHSS score (rho = 0.32; p < 0.001), stroke progression (rho = 0.29; p = 0.001), infarct volume (rho = 0.37; p < 0.001), mRS score (rho = 0.28; p = 0.001) and mortality (p = 0.010). CONCLUSIONS: Decreases in UA during the first week after onset of stroke correlates with more severe stroke, unfavorable stroke evolution, and poor long-term stroke outcome.

Evaluation of lactate as a marker of metabolic stress and cause of secondary damage in acute ischemic stroke or TIA.

BACKGROUND: Accumulation of lactate in ischemic regions has been documented in acute stroke. We evaluated the relation between lactate levels in blood and cerebrospinal fluid (CSF) and ischemic stroke evolution and outcome. METHODS: Lactate was measured in blood of 187 acute ischemic stroke and TIA patients at admission, 24 h, 72 h and 7 days after stroke onset. In a subpopulation of 85 stroke patients and in 51 controls, lactate was measured in CSF. Stroke evolution was evaluated by change in the NIHSS score within the first 72 h and by occurrence of progressing stroke. At 3 months after stroke, outcome was assessed on the basis of mortality rate and the modified Rankin Scale. RESULTS: We found no relation between lactate levels in blood and stroke evolution or outcome. Lactate in CSF was higher in stroke patients than in controls and correlated with stroke evolution and outcome. Multivariate regression analyses showed that CSF lactate levels, age and stroke severity are independent predictors for stroke evolution and outcome. CONCLUSIONS: Lactate levels in CSF, but not in blood, are a reliable marker for metabolic crisis in acute ischemic stroke and correlate with the stroke evolution in the subacute phase and with long-term outcome.

Faulty serotonin--DHEA interactions in autism: results of the 5-hydroxytryptophan challenge test.

BACKGROUND: Autism is accompanied by peripheral and central disorders in the metabolism of serotonin (5-HT). The present study examines plasma dehydroepiandrosterone-sulphate (DHEA-S) and the cortisol/DHEA-S ratio following administration of L-5-hydroxytryptophan (5-HTP), the direct precursor of 5-HT, to autistic patients. METHODS: Plasma DHEA-S levels were determined both before and after administration of 5-HTP or placebo, on two consecutive days in a single blind order in 18 male autistic patients and 22 matched healthy controls. RESULTS: The 5-HTP-induced DHEA-S responses were significantly higher in autistic patients than in controls. In baseline conditions, the cortisol/DHEA-S ratio was significantly higher in autistic patients than in controls. DISCUSSION: The results suggest that autism is accompanied by a major disequilibrium in the serotonergic system. The increased Cortisol (neurotoxic) versus DHEA-S (neuroprotective) ratio suggests that an increased neurotoxic potential occurs in autism. CONCLUSIONS: It is concluded that a disequilibrium in the peripheral and central turnover of serotonin and an increased neurotoxic capacity by glucocorticoids are important pathways in autism.

Effects of experimental panic on neuroimmunological functioning.

OBJECTIVE: Psychoimmunological research in panic disorder (PD) so far focussed on single time point evaluation in resting conditions. No robust evidence for changes in the immune system was found using this method. However, PD is characterized by the occurrence of unexpected panic attacks (PAs). The current research focuses on cytokine and acute phase protein (APP) levels and mitogen-induced cytokine secretion following 35% CO(2) inhalation-induced panic. METHODS: Eighteen PD patients and 18 matched healthy control subjects underwent both a placebo and a 35% CO(2) inhalation on separate days. Blood samples for cytokine and APP determination were taken before and after the inhalation. In addition to serum determination, whole blood samples were cultured and stimulated with mitogens for assessment of the functional capacity of the immune system. RESULTS: The 35% CO(2) inhalation induced significantly higher levels of anxiety in PD patients as compared to the control subjects, but no differences in immune parameters were found, either in basal conditions or after experimental panic induction. CONCLUSION: In our sample we do not find any changes in serum levels or functional capacity of several immunological parameters in the experimentally provoked PAs. Similar results have been found in social phobia, whereas in other affective disorders such as depression and posttraumatic stress disorder, immune changes are evident. Changes seem to coincide with alterations in hypothalamic-pituitary-adrenal (HPA) axis function. Therefore, the bidirectional communication pathway between the immune system and the HPA axis might play a role in some affective disorders, but it does not specifically seem to be involved in the etiology of PD.

Central serotonergic hypofunction in autism: results of the 5-hydroxy-tryptophan challenge test.

Some studies have suggested that disorders in the central serotonergic function may play a role in the pathophysiology of autistic disorder. In order to assess the central serotonergic turnover in autism, this study examines the cortisol and prolactin responses to administration of L-5-hydroxy-tryptophan (5-HTP), the direct precursor of 5-HT in 18 male, post-pubertal, Caucasian autistic patients (age 13-19 y.; I.Q.>55) and 22 matched healthy volunteers. Serum cortisol and prolactin were determined 45 and 30 minutes before administration of 5-HTP (4 mg/kg in non enteric-coated tablets) or an identical placebo in a single blind order and, thereafter, every 30 minutes over a 3-hour period. The 5-HTP-induced increases in serum cortisol were significantly lower in autistic patients than in controls, whereas there were no significant differences in 5-HTP-induced prolactin responses between both study groups. In baseline conditions, no significant differences were found in serum cortisol and prolactin between autistic and normal children. The results suggest that autism is accompanied by a central serotonergic hypoactivity and that the latter could play a role in the pathophysiology of autism.

Reference intervals for a complete blood count determined on different automated haematology analysers: Abx Pentra 120 Retic, Coulter Gen-S, Sysmex SE 9500, Abbott Cell Dyn 4000 and Bayer Advia 120.

We processed 317 samples from healthy adult volunteers for a complete blood count, including leukocyte differentials and reticulocyte parameters, through five new-generation haematology analysers: Abx Pentra 120 Retic, Coulter Gen-S, Sysmex SE 9500, Abbott Cell Dyn 4000 and Bayer Advia 120. From these data non-parametric 2.5-97.5 percentile reference intervals were calculated for all parameters on all analysers. Some differences were found compared with previously reported reference intervals. Reference intervals for platelet parameters and reticulocytes agreed with these usually accepted. For red blood cell parameters, including haemoglobin and haematocrit, and white blood cell count, including absolute white blood cell differentials, our calculated reference intervals were in agreement with less frequently cited earlier reports, but were lower compared to the usually accepted reference intervals.