IL Test Research Articles

La libertà religiosa alla prova del Covid-19. Asimmetrie giuridiche nello “stato di emergenza” e nuove opportunità pratiche di socialità

SOMMARIO: 1. Breve premessa orientativa - 2. Verso dove convergere - 3. Il nuovo statuto della solidarieta - 4. Rinnovate pratiche di relazioni sociali: il laboratorio della liberta religiosa - 5. Socializzare i diritti/espandere le liberta - 6. Il test della liberta religiosa in tempi di Coronavirus - 7. Fare tesoro dell’esperienza, modulare le risposte, organizzare il futuro. Religious freedom and the challenge of Covid-19. Legal asymmetries in the “state of emergency” and new opportunities for social actors ABSTRACT: The essay develops some concrete, both legal and political, analyses concerning the relationship between the Covid-19 pandemic and the fundamental right of religious freedom. The state of emergency that came about and the consequent decisions taken by the government to contain the spread of the coronavirus, have put pressure on certain fundamental freedoms and rights of both individuals and social formations, including religious freedom - according to some, more compressed from the point of view of its practical expressions. The question arises of how much, in the mid-long term, such measures will affect the structure of relations between the State and religious confessions and, more generally, religiosity as a sentiment widespread at societal level.

One-dimensional consolidation of overconsolidated clay using Constant Rate of Strain testing

The main method for the determination of consolidation parameters in Flanders (Belgium) is still the incremental loading test (IL test). This method can take up to several weeks for some typical Flemish overconsolidated (OC) clays. In theory, the same relationship between settlement and vertical stress can be obtained by performing a constant rate of strain test (CRS test). The main advantages of a CRS test are that the data is continuous and that the test can often be completed considerably faster than an IL test. In this paper, results of both IL and CRS tests on two undisturbed stiff OC clay samples of the same geological formation (Maldegem formation deposited during the Paleogene period) were compared. CRS tests were performed based on ASTM D4186, but constant stress stages were controlled using effective vertical stress instead of total vertical stress as most important adjustment to the standard. In addition, special attention was paid to the development of initial swell pressure and selecting an appropriate rate of strain for this clay with a very high plasticity. Similar values for compressibility and hydraulic conductivity were found using both IL and CRS test results. As the duration of a CRS test on this clay with low hydraulic conductivity can also take up to a few weeks, the time saving aspect of the test was found to be limited for the stiff OC clay tested. The uncertainty in estimating the pre-consolidation pressure and swell pressure was smaller using the continuous CRS test results.

Catalytic wet peroxide oxidation of imidazolium-based ionic liquids: Catalyst stability and biodegradability enhancement

The catalytic wet peroxide oxidation (CWPO) of the imidazolium-based ionic liquids 1-butyl-3-methylimidazolium chloride (BmimCl), 1-butyl-3-methylimidazolium acetate (BmimAc), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BmimNTf2), 1-hexyl-3-methylimidazolium chloride (HmimCl) and 1-decyl-3-methylimidazolium chloride (DmimCl) was examined by using a Fe catalyst supported on alumina (Fe2O3/Al2O3) that was prepared by incipient wetness impregnation. Variable H2O2 doses from 0.5 to 1.5 times the stoichiometric value provided similar results in terms mg TOC removed per mg H2O2 decomposed at 80 °C (0.033 mgTOC mgH2O2−1), all allowing complete Bmim+ removal. Raising the reaction temperature to 90 °C increased the mineralization rate up to 40% TOC conversion. Differences in TOC conversion among counteranions (chloride, acetate and NTf2−) were negligible. A plausible reaction pathway is propose involving hydroxylated compounds and short-chain organic acids as reaction byproducts. CWPO markedly increased the subsequent biodegradability of the IL test solutions and led there to TOC conversions after CWPO-biodegradability assays of 55–60%. The Fe2O3/Al2O3 catalyst exhibited high long-term stability; thus, it retained most of its properties and underwent negligible Fe leaching.

Intragastric fat self-administration is impaired in GPR40/120 double knockout mice

Mice acquire strong preferences for flavors paired with intragastric (IG) fat infusions. This IG fat conditioning is attenuated in double knockout (DoKO) mice missing GPR40 and GPR120 fatty acid receptors. Here we determined if GPR40/120 DoKO mice are also impaired in IG fat self-administration in an operant lick task. In daily 1-h sessions the mice were trained with a sipper spout that contained dry food pellets; licks on the spout triggered infusions of IG fat (Intralipid). The training sessions were followed by test sessions with an empty spout. GPR40/120 DoKO mice self-infused more 20% fat than wild type (WT) C57BL/6 mice in training with a food-baited spout (2.4 vs. 2.0kcal/h) but self-infused less 20% fat than WT mice in empty spout tests (1.2 vs. 1.7kcal/h). The DoKO mice also self-infused less 5% fat than WT mice (0.6 vs. 1.3kcal/h) although both groups emitted more licks for 5% fat than 20% fat. The DoKO and WT mice did not differ, however, in their self-infusion of 12.5% glucose (1.5 vs. 1.6kcal/h), which is isocaloric to 5% fat. A second 5% IL test showed that the DoKO mice reverted to a reduced self-infusion compared to WT mice. When the infusion was shifted to water, WT mice reduced licking in the first extinction session, whereas DoKO mice were less sensitive to the absence of infused fat. Our results indicate that post-oral GPR40/120 signaling is not required to process IG fat infusions in food-baited spout training sessions but contributes to post-oral fat reinforcement in empty spout tests and flavor conditioning tests.

D-dimer levels and 90-day outcome in patients with acute pulmonary embolism with or without cancer

The prognostic value of D-dimer testing in patients with acute pulmonary embolism (PE) has not been thoroughly studied. We used the RIETE Registry data to assess the 90-day prognostic value of increased IL Test D-dimer levels at baseline in patients with PE, according to the presence or absence of cancer. As of May 2013, 3,283 patients with acute PE underwent D-dimer testing using IL Test D-dimer. Among 2,588 patients without cancer, those with D-dimer levels in the highest quartile had a higher rate of fatal PE (2.6% vs. 0.9%; p=0.002), fatal bleeding (1.1% vs. 0.3%; p=0.017) and all-cause death (9.1% vs. 4.4%; p<0.001) at 90 days compared with those with levels in the lowest quartiles. Among 695 patients with cancer, those with levels in the highest quartile had a similar rate of fatal PE or fatal bleeding but higher mortality (35% vs. 24%; p<0.01). On multivariate analysis, non-cancer patients with D-dimer levels in the highest quartile had an increased risk for fatal PE (odds ratio [OR]: 3.3; 95% CI: 1.6-6.6), fatal bleeding (OR: 4.3; 95% CI: 1.4-13.7) and all-cause death (OR: 2.1; 95% CI: 1.4-3.1) compared with patients with levels in the lowest quartiles. Non-cancer patients with acute PE and IL Test D-dimer levels in the highest quartile had an independently higher risk for fatal PE, fatal bleeding and all-cause death at 90 days than those with levels in the lowest quartiles. In patients with cancer, D-dimer levels failed to predict fatal PE or fatal bleeding.

Pulmonary embolism: investigation of the clinically assessed intermediate risk subgroup

The simplified Wells pre-test probability scoring algorithm for pre-investigation evaluation of pulmonary emboli (PE) is a commonly utilised and validated assessment tool. We sought to identify whether use of a dichotomised scoring system altered the overall negative predictive value (NPV) in patients referred for CT pulmonary angiography (CTPA) assessment of suspected PE. Prospective data collection of all patients referred for CTPA evaluation of suspected acute PE during a 3 year period was carried out. Pre-test risk stratification was performed according to simplified Wells criteria in conjunction with plasma d-Dimer (Bio-Pool and IL test) estimation. Retrospective dichotomisation was also performed. 2531 patients were investigated for suspected acute PE; acute thromboemboli were confirmed in 22.7%. The overall NPV for negative d-Dimer and intermediate pre-test probability (PTP) was 98.9% [95% confidence interval (CI) 96.3-99.7%]; with retrospective dichotomisation, the NPV for the PE unlikely group was 99.0% (95% CI 94.8-99.8%). Implementation of dichotomised scoring, excluding PE unlikely with negative d-Dimer cases from further imaging, would have yielded a 4% reduction in CTPA referral pathway imaging at our institution. We demonstrate no significant difference between exclusion in the intermediate subgroup and the retrospectively dichotomised PE unlikely group and demonstrate the high negative predictive power of the Bio-Pool and IL tests in conjunction with the Wells PTP tool. Prior to implementation of new guidelines for exclusion of patients with suspected PE from further imaging, hospitals should audit their own practice and validate the d-Dimer assay utilised at their institution.

D-dimer levels and 15-day outcome in acute pulmonary embolism. Findings from the RIETE Registry.

A number of variables have been evaluated for risk stratification in patients with acute pulmonary embolism (PE). Whereas increased D-dimer levels have been associated with mortality at 3 months, its role in predicting short-term outcome (the period of time during which any therapeutic decision has to be taken) remains unclear. RIETE is an ongoing, prospective registry of consecutive patients with acute venous thromboembolism. We assessed the prognostic value of D-dimer levels at baseline, measured with an automated latex agglutination test (IL Test D-dimer), on the 15-day outcome in patients with acute PE. Overall mortality, fatal PE and major bleeding rates were compared by quartile. As of February 2008, 1707 patients with acute PE underwent D-dimer testing. Of these, 72 patients (4.2%) died during the first 15 days, 11 (0.6%) had recurrent PE, and 29 (1.7%) had major bleeding. Overall mortality increased with increasing D-dimer levels, from 2.7% in the first quartile (< 1050 ng mL(-1)) to 7.0% in the fourth quartile (>or= 4200 ng mL(-1)). The rates of fatal PE and major bleeding also increased. On multivariate analysis, patients with D-dimer levels in the fourth quartile had an increased risk for overall death (odds ratio, 1.8; 95% CI, 1.1-3.2), fatal PE (odds ratio, 2.0; 95% CI, 1.0-3.8) or major bleeding (odds ratio, 3.2; 95% CI, 1.5-7.0). PE patients with D-dimer levels in the fourth quartile had an increased incidence of overall death, fatal PE and major bleeding within 15 days both before and after multivariate adjustment.

D-dimer levels correlate with mortality in patients with acute pulmonary embolism: Findings from the RIETE registry

Few studies have addressed the prognostic implications of D-dimer in patients with pulmonary embolism. The aim of this study was to investigate the correlation between D-dimer levels and mortality in patients with pulmonary embolism. Observational study. Hospitals participating in the Registro Informatizado de la Enfermedad Tromboembólica (RIETE). A total of 588 consecutive patients with symptomatic pulmonary embolism who were included in the RIETE between March 2001 and December 2004. Quantitative D-dimer measurement was performed on admission using an automated latex agglutination test (IL Test D-dimer). All patients underwent clinical follow-up for 3 months. Overall mortality rate was 10.5%. The cause of death was pulmonary embolism in 18 patients (3.0%), fatal bleeding in one patient (0.2%), and other causes in 43 patients (7.3%). There were 28 (4.8%) nonfatal venous thromboembolism recurrences and 35 (6.0%) nonfatal bleeding episodes. The incidence of D-dimer 500-2499 ng/mL, D-dimer 2500-4999 ng/mL, and D-dimer >or=5000 ng/mL was 47.8%, 26.0%, and 20.4%, respectively. Compared with patients with D-dimer 500-2499 ng/mL, the relative risk (odds ratio) of overall mortality was 1.91 (95% confidence interval 0.91-4.09) and 2.94 (95% confidence interval 1.42-6.25) in patients with D-dimer 2500-4999 ng/mL and D-dimer >or= 5000 ng/mL, respectively (p = .032). Patients with D-dimer >or=5000 ng/mL showed higher risk of death from fatal pulmonary embolism (odds ratio 4.4, 95% confidence interval 0.5-33.0) than death from other causes (odds ratio 2.1, 95% confidence interval 0.7-6.0). Elevated D-dimer levels were associated with more severe disease, as assessed by clinical features. In patients who present with pulmonary embolism, D-dimer concentration is an independent predictive factor associated with all-cause and pulmonary embolism-related death. D-dimer >or=5000 ng/mL occurs in about one in five patients and is associated with a 2.9-fold increased risk of overall mortality. These results suggest that D-dimer quantification could be a useful biomarker and help determine initial therapies.

Latex-Enhanced Immunoassay D-dimer and Blood Gases Can Exclude Pulmonary Embolism in Low-Risk Patients Presenting to an Acute Care Setting

Pulmonary embolism (PE) is common, and diagnosis is often difficult. Investigation has traditionally required expensive imaging procedures that are frequently nondiagnostic. Consequently, current practice favors noninvasive diagnosis of PE using algorithms combining risk assessment and d-dimer. Despite the proven safety of this approach, concern persists about such strategies to exclude PE, largely due to variable d-dimer sensitivity. The aim of this study was to prospectively assess the safety of a new algorithm combining a novel, rapid d-dimer test (IL Test; Instrumentation Laboratory; Lexington, MA), Pa(O2) measurement, and risk factor assessment in excluding PE in subjects presenting to an acute care setting. All patients aged 18 to 60 years presenting to the emergency department of Christchurch Hospital with suspected PE underwent measurement of d-dimer (IL Test latex-enhanced immunoassay) and Pa(O2), and were assessed for the presence of major clinical risk factors. Those with no risk factors, normal d-dimer findings, and Pa(O2) > or = 80 mm Hg (study arm A) were discharged and followed up by telephone questionnaires over 12 months. Those with elevated d-dimer levels, Pa(O2) < 80 mm Hg, or one or more risk factors (study arm B) were managed as per hospital guidelines. Outcome data were collected on these patients. Our primary outcome was incidence of PE in group A during the first 3-month follow-up period. Three hundred twenty-eight patients were enrolled, of whom 149 were assigned to group A and 179 were assigned to group B. In none of the group A patients was PE diagnosed over the subsequent 3-month period (0%; 95% confidence interval, 0 to 2.1%). PE was diagnosed in 37 group A patients (21%). The latex-enhanced immunoassay d-dimer and normal arterial oxygen pressure levels can safely exclude PE in a low-risk population presenting to an acute care setting. While these results cannot be extrapolated to all patients with suspected PE, they do confirm the safety of this approach in a population with a low underlying risk of PE.

An evaluation of rapid D‐dimer assays for the exclusion of deep vein thrombosis

We evaluated the performance of eight d-assays for the exclusion of deep vein thrombosis (DVT); Biopool AutoDimer, Biopool MiniQuant, bioMèrieux MDA D-Dimer, VIDAS, Dade Behring D-Dimer Plus, Trinity Biotech AMAX, NycoCard D-dimer and IL Test D-Dimer. The assays were evaluated both as stand-alone tests, and in combination with pretest probability (PTP). D-dimer assays and PTP assessment were performed on 410 patients presenting to the emergency department with suspected acute DVT. DVT was diagnosed in 76 of 410 patients (18.5%) by compression ultrasound or other imaging techniques, as required. Receiver operator characteristics analysis established optimum cut-off values and these were compared with manufacturer's cut-off values where provided. As stand-alone tests, the assays varied immensely regarding cut-off value, negative predictive value (NPV 93-100%) and specificity (0-67%). At least one patient with confirmed DVT had a low d-dimer level by each method: to achieve 100% sensitivity it would be necessary to reduce cut-off values to levels below clinical usefulness. When low d-dimer was used in combination with PTP, six of eight methods achieved > or =98% NPV, with a diagnosis of DVT excluded in 16-44% of patients without the requirement for diagnostic imaging. The highly variable diagnostic performance of these d-dimer assays means that some assays are unsuitable for certain diagnostic strategies. However, our data suggest that the combination of sensitive D-dimer assays with an assessment of PTP may be used to exclude a diagnosis of DVT.

In Vivo and In Vitro Evaluation of the Heparin Management Test versus the Activated Coagulation Time for Monitoring Anticoagulation Level in Aprotinin-Treated Patients during Cardiac Surgery

Monitoring whole blood anticoagulation therapy with the activated coagulation time (kaolin ACT) and the heparin management test (HMT) were correlated in vivo with the plasma anti-activated factor X (anti-Xa) heparin concentration in patients who received variable doses of aprotinin and in vitro in the presence of increasing concentrations of aprotinin. In 38 elective cardiac surgical patients who received an average heparin dose of 400 IU/kg and an average total aprotinin dose of 3.6 10(6) kallikrein-inhibiting units (KIU), ACT and HMT were measured in duplicate 6 times intraoperatively at predetermined intervals. Blood samples at each interval were also assayed for the anti-Xa plasma heparin concentration with the IL Test heparin chromogenic assay. The influence of increasing concentrations of aprotinin on HMT and ACT was also measured in vitro by using blood samples containing 6 IU/mL heparin from 6 additional patients after adding specific aliquots of aprotinin to achieve concentrations of 50, 100, 200, and 300 KIU/mL aprotinin. Linear regression analysis was used to compare HMT and ACT against anti-Xa. A P level <.05 was required for statistical significance. Duplicate measurements were taken at all intervals, and HMT and ACT values were significantly correlated, both with each other (r = 0.86; P < .01) and with anti-Xa activity (HMT, r = 0.81 [P < .01]; ACT, r = 0.71 [P < .01]). Aprotinin prolonged both the kaolin ACT and the HMT time in a dose-dependent manner (P < .05), and its influence was significantly less in vivo on the HMT time than on the kaolin ACT (P < .001). The abilities of the HMT and the kaolin ACT to measure anticoagulation effects were not significantly different. Aprotinin prolonged both the kaolin ACT and the HMT time in a dose-dependent manner, but the HMT was significantly less affected by aprotinin in vivo. The HMT is a reliable alternative to measuring the ACT in cardiac operations and may offer greater accuracy in aprotinin-treated patients.

Screening for proximal deep vein thrombosis after acute ischemic stroke: a prospective study using clinical factors and plasma d‐dimers

Deep vein thrombosis (DVT) remains common in patients with acute ischemic stroke (AIS) receiving aspirin and graded compression stockings (considered standard thromboprophylaxis in the UK), most events occurring in patients with Barthel indices (BI) of <9 ('severe stroke') around the time of admission. In the absence of data indicating improved clinical outcomes with use of low-dose anticoagulant thromboprophylaxis, we evaluated the hypothesis that plasma D-dimers (D-d) might be a valuable initial screening test for proximal DVT (PDVT), facilitating selective use of imaging. One hundred and two unselected AIS-patients receiving aspirin/graded compression stockings thromboprophylaxis were screened for DVT using magnetic resonance direct thrombus imaging, a highly accurate non-invasive technique which directly visualizes thrombus. D-d (VIDAS and IL test D-d assays) were measured on recruitment and at weekly intervals. Median D-d were significantly higher throughout the study in patients with severe stroke who developed PDVT vs. those with severe stroke not developing PDVT, differences being most marked around day 9. Depending on the discriminatory threshold used, a single D-d measurement at this time in patients with severe-AIS allowed identification of a subgroup with ~50% prevalence of PDVT. Sensitivity of these strategies for PDVT was 67-83%, at a cost of imaging 22-30% of the entire cohort of patients. A single measurement of BI around the time of admission and D-d level at day 9 in AIS-patients receiving aspirin/graded compression stockings thromboprophylaxis allows identification of a subgroup containing a substantial proportion of all PDVTs who could be selectively imaged.

Extensive evaluation of the instrumentation laboratory IL test D-Dimer immunoturbidimetric assay on the ACL 9000 determines the D-Dimer cutoff value for reliable exclusion of venous thromboembolism.

The clinical diagnosis of venous thromboembolism (VTE), which includes both deep vein thrombosis (DVT) and pulmonary embolism (PE), is often difficult and requires a number of imaging tests plus clinical assessment. It is now accepted that pretest clinical probability of disease plus a sensitive, quantitative D-Dimer assay can be used to reliably exclude VTE. In design of diagnostic strategies for VTE it is recommended that the D-Dimer assay be evaluated for sensitivity and specificity in well-designed, blinded studies using a cohort of patients for whom the assay will ultimately be used. Therefore we evaluated the IL Test D-Dimer on the ACL 9000 automated coagulation analyzer for its sensitivity and specificity in the diagnosis of VTE. A total of 512 patients admitted to the emergency department of Providence Hospital with suspected VTE were included in the dataset. Our aim was to find the clinically meaningful IL Test D-Dimer cutoff value, which would give us 100% sensitivity and the highest possible specificity for exclusion of VTE. Patients were categorized clinically into low, medium, or high pretest probability and had computed tomographic and/or ventilation-perfusion scans for investigation of PE and ultrasound studies for suspected DVT, with the laboratory blinded to the clinical findings. Of the 511 patients, 28 (5.4%) had confirmed VTE (PE and/or DVT) based on imaging and clinical studies. Applying receiver operating characteristic curve (ROC) analysis, we determined from our study that a cutoff value of 237 ng/mL IL Test D-Dimer gave a 100% sensitivity with a specificity of 38% for detection of VTE. The findings demonstrate that a diagnostic strategy using the IL Test D-Dimer assay as a first-line test in combination with pretest probability is safe and can be used in patients with suspected VTE. In conclusion, patient analysis results indicating low or moderate pretest probability for VTE and a negative IL Test D-Dimer (cutoff value of 237 ng/mL) assay result on the ACL 9000 reliably exclude VTE (both PE and DVT). We expect that inclusion of the rapid IL Test D-Dimer assay for assessment of suspected VTE in the emergency department at Providence will result in improved patient diagnosis and therapy, reduction in unnecessary radiological investigations, and lowering of overall costs associated with investigation of patients suspected of having VTE disease.

Trace elements as a component of oxidative stress in COPD.

The purpose of this study was to assess the serum concentrations of those trace elements that act as a component of oxidative stress in COPD patients. Clinically stable COPD outpatients (n = 26) and healthy controls (n = 24) were studied. Serum concentrations of copper (Cu) and zinc (Zn) were determined using a Varian Spectra AA220 flame atomic absorption spectrophotometer. Serum concentration of iron (Fe) was measured by the ferene assay, using a commercially available kit (IL Test Iron) with the ILAb 900 autoanalyser. The lipid peroxidation product malondialdehyde (MDA) in serum samples was measured spectrophotometrically in terms of TBARS (thiobarbituric acid reactive substances). The serum MDA concentration in COPD patients was found to be similar to the control group (0.68 +/- 0.15 nmol/mL vs 0.62 +/- 0.13 nmol/mL, respectively; P= 0.163). The serum concentrations of the trace elements in both study groups were in the normal reference range. There was no difference in Fe concentration between COPD patients and the control group (0.81 +/- 0.38 micro g/mL vs 0.92 +/- 0.41 micro g/mL; P= 0.360). Copper concentrations were higher (1.06 +/- 0.26 microg/mL vs 0.92 +/- 0.19 microg/mL; P <0.040); while zinc was lower in the COPD group compared to the controls (0.83 +/- 0.25 microg/mL vs 1.03 +/- 0.23 microg/mL; P= 0.006). Serum Zn concentrations were lower in the severe COPD patients compared to mild-moderate COPD patients (P = 0.038). The results of this study indicate that there are alterations in serum concentrations of trace elements in COPD patients, suggesting that they may play a role in the pathophysiology of this disease by virtue of their role in oxidative stress. We recommend further studies on the role of trace elements in the pathophysiology of COPD, their association with markers of oxidant/antioxidant status and on the clinical significance of their deficiency.

The relationship between acute ischaemic stroke and plasma D-dimer levels in patients developing neither venous thromboembolism nor major intercurrent illness.

The true relationship between plasma D-dimers and acute ischaemic stroke (AIS) is uncertain as previous studies investigating this have not screened for subclinical deep vein thrombosis. We addressed this as part of a study in which we screened AIS patients for venous thromboembolism (VTE). We also assessed the performance characteristics of two D-dimer assays as exclusionary tests for VTE in these patients. One hundred and two unselected AIS patients were screened for VTE using magnetic resonance direct thrombus imaging. D-dimers were analysed on days 2, 9, 14 and 21 using the VIDAS immunofluorescent assay (cut-off >or= 500 ng/ml) and the IL test D-dimer immunoturbidimetric assay (cut-off >or= 255 ng/ml). The relationship between D-dimers and AIS was examined in 52 patients neither developing VTE nor intercurrent illness. D-dimers were elevated throughout the study. Median values at the four time points were 652, 692, 737 and 686 ng/ml (VIDAS assay) and 260.5, 268.5, 273 and 283 ng/ml (IL assay). D-dimers were higher in patients aged older than 70 years, with severe stroke or with total anterior circulation infarcts: only age older than 70 years was significantly associated with D-dimer values greater than the median on univariate and multivariable analysis. Both assays were 100% sensitive for VTE. Specificities were 30% (VIDAS assay) and 34% (IL assay). Specificity was adversely affected by age older than 70 and severe versus non-severe stroke. D-dimers are elevated in the first 3 weeks post-AIS after eliminating the confounding effect of subclinical deep vein thrombosis. The VIDAS and IL assays remained sensitive tests for VTE but the specificity was low, limiting their exclusionary efficiency in these patients.

Determination of α-Amylase Activity in Serum and Dialysate from Patients Using Icodextrin-Based Peritoneal Dialysis Fluid

Low serum activity of alpha-amylase has been reported in peritoneal dialysis (PD) patients following treatment with icodextrin-based peritoneal dialysis fluid (IPDF). However, these results have been questioned because icodextrin interferes with the polysaccharide reagent included in the assay as a substrate for alpha-amylase in the sample. We adapted a routine method using p-nitrophenol maltoheptaoside as substrate for the analysis of total alpha-amylase in serum and dialysate from 27 patients using IPDF. Serum from 12 healthy volunteers and serum and dialysate from 19 PD patients using glucose-based peritoneal dialysis fluid (GPDF) were used as controls. For the PD patients, time on dialysis ranged from 1 to 24 months (mean 5.7 months) and time of exposure to IPDF ranged from 1 to 52 weeks. To test for interference and recovery, and thus to validate the alpha-amylase assay, samples were spiked with IPDF and synthetic alpha-amylase. This revealed that addition of up to 75% IPDF did not interfere with the assay. Furthermore, alpha-amylase was fully recovered when spiked in serum from patients treated with IPDF. We show that total alpha-amylase activity is considerably lower in the serum of IPDF patients (20.3 +/- 16.5 U/L, p < 0.001) than GPDF patients (85.5 +/- 51.7 U/L) and healthy persons (55.1 +/- 13.6 U/L). We have shown that the IL method (ILTest; Instrumentation Laboratory, Lexington, MA, USA) measures alpha-amylase activity in samples containing icodextrin metabolites. The clinical significance of reduced plasma alpha-amylase activity, as well as the relative importance of pancreatic versus salivary and tissue-bound alpha-amylase, in PD patients using IPDF is not known.

Multicentre Evaluation of IL Test™ Free PS: A Fully Automated Assay to Quantify Free Protein S

Deficiency of the anticoagulant vitamin K-dependent protein S (PS) is associated with increased risk of venous thrombosis. In human plasma, PS circulates in two forms: as free protein (free PS) and PS bound to C4b-binding protein (C4BP), a regulator of the complement system. Assays for free PS have higher sensitivity and specificity for protein S deficiency than assays for total protein S. We have extensively evaluated the analytical performance of a novel assay for free PS, the IL Test Free Protein S, which takes advantage of the affinity of C4BP for free PS, and compared its performance to existing methods. IL Test Free Protein S is a rapid, fully automated turbidimetric assay consisting of two reagents: a C4BP coated latex and an anti-PS monoclonal antibody coated latex. The test range, precision and linearity were adequate and the assay tolerated high concentrations of interfering substances of clinical significance. The reference range agreed with previously published studies. The analysis of 903 patient samples belonging to 20 different clinical categories with the new assay yielded free PS results that agreed well with those obtained using the assays established in the participating laboratories. The study demonstrated the IL Test Free Protein S to be rapid, reliable and easy to perform.

Effect of Patient Weight on the Anticoagulant Response to Adjusted Therapeutic Dosage of Low-Molecular- Weight Heparin for the Treatment ofVenous Thromboembolism

Data evaluating the safety of using weight-based dosing of low-molecular-weight heparin (LMWH) in obese patients are limited. Some manufacturers have recommended a maximum daily dose of LMWH not to be exceeded. The purpose of this study was to determine if body weight influenced the anticoagulant response to a weight-based dose of LMWH for the treatment of venous thromboembolism. Patients with serum creatinine levels <150 µmol/l receiving the LMWH , dalteparin 200 anti-Xa IU/kg based on actual body weight subcutaneously once daily for the treatment of deep vein thrombosis or pulmonary embolism, were eligible for the study. Patients received a minimum of 5 days LMWH treatment. Patients had peak anti-Xa levels (IL Test Chromogenic assay) measured 3–4 h following their day 3 injection and trough anti-Xa levels measured immediately prior to injections on day 3 and 5. No dose adjustments were made on the basis of the anti-Xa levels. Patients were a priori stratified into three weight classes: (A) within 20% of ideal body weight (IBW) (n = 13); (B) 20–40% of IBW (n = 14), and (C) greater than 40% of IBW (n = 10). The largest patient weighed 190 kg and had a body mass index of 58. Mean daily LMWH doses were 14,030, 17,646 and 23, 565 IU for groups A, B and C, respectively. Mean (SD) trough anti-Xa levels on day 3 were 0.12 (0.05) anti-Xa IU/ml for group A, 0.11 (0.03) anti-Xa IU/ml for group B and 0.11 (0.03) anti-Xa IU/ml for group C (p > 0.2). Similar trough anti-Xa levels were observed on day 5. Mean (SD) peak anti-Xa levels on day 3 were 1.01 (0.20) anti-Xa IU/ml, 0.97 (0.21) anti-Xa IU/ml and 1.12 (0.22) anti-Xa IU/ml for groups A, B and C, respectively (p > 0.2). No thromboembolic or bleeding complications occurred during LMWH therapy in any patients. These findings suggest that body mass does not appear to have an important effect on the response to LMWH up to a weight of 190 kg in patients with normal or near normal renal function.

Use of a fixed activated partial thromboplastin time ratio to establish a therapeutic range for unfractionated heparin.

The commonly recommended therapeutic range for patients receiving unfractionated heparin of 1.5 to 2.5 times the control activated partial thromboplastin time (aPTT) is not universally applicable. It has been suggested that the therapeutic range for each aPTT reagent should be based on plasma heparin levels. We sought to identify an aPTT ratio that corresponds to therapeutic anti--factor Xa heparin levels for combinations of several reagents and coagulometers that are commonly used. Citrated plasma was collected from 126 unselected patients receiving unfractionated heparin. Four automated coagulometers and 6 commercial aPTT reagents were used to measure the aPTT. Plasma anti--factor Xa levels were measured by means of a commercially available assay. The relationship between the aPTT results and anti-factor Xa heparin levels for each reagent-coagulometer combination was determined by linear regression analysis, and the aPTT results corresponding to therapeutic anti--factor Xa heparin levels were calculated. For all reagent-coagulometer combinations studied, an aPTT ratio of 1.5 resulted in anti--factor Xa heparin levels considerably below the lower limit of the therapeutic range. When the aPTT was performed on any of the coagulometers assessed with the use of Actin (Dade Diagnostics, Aguada, Puerto Rico) and IL Test (Instrumentation Laboratories, Fisher Scientific, Unionville, Ontario) reagents, aPTT ratios necessary to achieve therapeutic anti--factor Xa heparin levels approximated 2.0 to 3.5. For laboratories that cannot perform heparin levels, the use of less responsive reagents and any of the coagulometers studied, along with target aPTT ratio between 2.0 and 3.5, appears to be a reasonable alternative.

Interactions of glucagon and free fatty acids with insulin in control of glucose metabolism

To study the interactions of physiological glucagon and free fatty acids (FFA) concentrations with insulin in the control of glucose metabolism, we determined in normal subjects the response of endogenous glucose production (EGP) and glucose utilization (Rd) to a progressive and moderate increase of insulinemia in the presence of glucagon and FFA levels either decreased (somatostatin [SRIF] and insulin infusion, C test) or maintained to normal postabsorptive values isolated (SRIF + insulin + glucagon infusion, G test; SRIF + insulin + Intralipid infusion, IL test) or in association (SRIF + insulin + glucagon + Intralipid infusion, IL + G test). Compared with the C test, maintenance of glucagon level had only small and inconsistent effects on glucose Rd, but induced a shift to the right of the dose-response curve to insulin of EGP (apparent ED 50: C test, 10.9 mU · L −1; G test, 15.2 mU · L −1). Intralipid infusion resulted, whether glucagon was substituted or not, in a near total suppression of the insulin-induced increase of glucose Rd (Rd at the end of the tests: C test, 6.13 ± 0.85 mg · kg −1 · min −1; G test, 7.29 ± 0.87 mg · kg −1 · min −1; IL test, 3.30 ± 0.65 mg · kg −1 · min −1; IL + G test, 3.57 ± 0.42 mg · kg −1 · min −1). In the absence of glucagon, substitution Intralipid infusion also antagonized the action of insulin on EGP. However, this effect was no longer apparent when glucagon was replaced (dose-response curve to insulin of EGP during the G and the IL + G test were comparable). Thus, small variations of glucagon and FFA levels appear to have large impacts on the responses to insulin, respectively, of EGP and glucose Rd. These results suggest that mild increases in glucagon and/or FFA levels or a lack of appropriate decrease in response to raised insulin levels could result in a resistance to insulin of glucose metabolism.