ELIMINATE: a PCR record-based macroelimination project for systematic recall of HCV-RNA-positive persons in Austria

BACKGROUND AND AIMS

Micro-elimination projects targeted to specific hepatitis C virus (HCV) risk populations have been successful. Systematic identification of persons with HCV viremia, regardless of risk group, based on already available laboratory records may represent an effective macroelimination approach to achieve global HCV elimination.

METHODS

Persons with a last positive HCV-RNA PCR result between 2008-2020 in the reference virology laboratories in eastern Austria were identified. First, (i) we described their demographic characteristics, (ii) we systematically recalled persons to the respective centers and (iii) started antiviral treatment if HCV-RNA viremia was confirmed, and (iv) recorded sustained virologic response (SVR). This interim report includes the preliminary results from 8 participating centers.

RESULTS

During the study period 22,682 persons underwent HCV-RNA PCR testing, 11,216 (49.4%) were positive at any point in time, and 6006 (26.5%) showed detectable HCV-RNA at the last PCR test, suggesting ongoing HCV viremia. At the time of this interim report, 2546/6006 HCV-RNA PCR(+) persons were evaluated: 443/2546 (17.4%) had died, 852/2546 (33.5%) had invalid contact data, and 547/2546 (21.5%) had achieved SVR between data retrieval and recall. Contact could be established in 236/704 (33.5%) of the remaining target population with 97/236 (41.1%) presenting at the clinic for treatment evaluation. Ultimately, 71/236 (30.1%) started antiviral treatment and SVR was documented in 47/71 (66.2%).

CONCLUSION

This ELIMINATE project based on systematic assessment of HCV-RNA PCR-records, identified 6006 persons with potential persisting HCV viremia. Invalid contact data and missed visits for treatment evaluation were the main barriers towards HCV elimination within this project. Importantly, many subjects with HCV viremia lost to follow-up were successfully linked to care and started antiviral treatment.

Performance of SARS-CoV-2 nucleic acid amplification testing in Austria as measured by external quality assessment schemes during 3 years of the COVID-19 pandemic: an observational retrospective study

BACKGROUND

The aim of external quality assessment (EQA) schemes is to evaluate the analytical performance of laboratories and test systems in a near-to-real-life setting. This monitoring service provides feedback to participant laboratories and serves as a control measure for the epidemiological assessment of the regional incidence of a pathogen, particularly during epidemics. Using data from EQA schemes implemented as a result of the intensive effort to monitor SARS-CoV-2 infections in Austria, we aimed to identify factors that explained the variation in laboratory performance for SARS-CoV-2 detection over the course of the COVID-19 pandemic.

METHODS

For this observational study, we retrospectively analysed 6308 reverse transcriptase quantitative PCR (RT-qPCR) test results reported by 191 laboratories on 71 samples during 14 rounds of three SARS-CoV-2 pathogen detection EQA schemes in Austria between May 18, 2020, and Feb 20, 2023. We calculated the overall rates of false and true-negative, false and true-positive, and inconclusive results. We then assessed laboratory performance by estimating the sensitivity by testing whether significant variation in the odds of obtaining a true-positive result could be explained by virus concentration, laboratory type, or assay format. We also assessed whether laboratory performance changed over time.

FINDINGS

4371 (93·7%) of 4663 qPCR test results were true-positive, 241 (5·2%) were false-negative, and 51 (1·1%) were inconclusive. The mean per-sample sensitivity was 99·7% in samples with high virus concentrations (1383 [99·4%] true-positive, three [0·2%] false-negative, and five [0·4%] inconclusive results for 1391 tests in which the sample cycle threshold was ≤32), whereas detection rates were lower in samples with low virus concentrations (mean per-sample sensitivity 92·5%; 2988 [91·3%] true-positive, 238 [7·3%] false-negative, and 46 [1·4%] inconclusive results for 3272 tests in which the cycle threshold was >32). Of the 1645 results expected to be negative, 1561 (94·9%) were correctly reported as negative, 10 (0·6%) were incorrectly reported as positive, and 74 (4·5%) were reported as inconclusive. Notably, the overall performance of the tests did not change significantly over time. The odds of reporting a correct result were 2·94 (95% CI 1·75-4·96) times higher for a medical laboratory than for a non-medical laboratory, and 4·60 (2·91-7·41) times greater for automated test systems than for manual test systems. Automated test systems within medical laboratories had the highest sensitivity when compared with systems requiring manual intervention in both medical and non-medical laboratories.

INTERPRETATION

High rates of false-negativity in all PCR analyses evaluated in comprehensive, multiple, and repeated EQA schemes outline a clear path for improvement in the future. The performance of some laboratories (eg, non-medical laboratories or those using non-automated test systems) should receive additional scrutiny-for example, by requiring additional EQA schemes for certification or accreditation-if the aggregated data from EQA rounds suggest lower sensitivity than that recorded by others. This strategy will provide assurances that epidemiological data as a whole are reliable when testing on such a large scale. Although performance did not improve over time, we cannot exclude extenuating circumstances-such as shortages and weakened supply chains-that could have prevented laboratories from seeking alternative methods to improve performance.

FUNDING

None.

Late-stage presentation with decompensated cirrhosis is alarmingly common but successful etiologic therapy allows for favorable clinical outcomes

INTRODUCTION

Liver cirrhosis accounts for considerable morbidity and mortality worldwide and late presentation limits therapeutic options. We aimed to assess characteristics of patients with liver cirrhosis at the time of first presentation and during their clinical course.

METHODS

Patients with cirrhosis as evident by presence of varices at endoscopy, liver stiffness ≥15kPa at elastography, or ascites requiring paracentesis between Q1/2015-Q2/2020 were retrospectively included. Clinical, laboratory, and imaging data were collected from medical records at presentation and last follow-up.

RESULTS

476 patients were included (alcohol-related liver disease, ALD: 211, 44.3%; viral hepatitis: 163, 34.2%). Of these, 106 patients (22.3%) and 160 patients (33.6%) presented already with Child-Pugh C and MELD >15, respectively, and decompensation events were registered in 50% (238 patients) at baseline, and even in 75.4% of ALD patients. During a median follow-up of 11.0 (IQR 4-24) months, 116 patients died. Two-year survival was worse for patients with ALD than for viral hepatitis (71.1% vs. 90.2%, log rank p<0.001). We observed the highest percentage of portal-vein thrombosis (30.0%), hepatocellular carcinoma (15.0%), and death (45.0%) in the MAFLD group (n = 20). Patients cured from hepatitis C showed significant improvements in platelet count (147 to 169 G/L, p<0.001) and liver stiffness (26.2 to 17.7 kPa, p<0.001), while ALD patients improved in Child-Pugh score (8.6 to 7.6, p<0.001) during follow-up. With increasing Child Pugh score and MELD, we found increasing serum concentrations of CRP (p<0.001) and an inverse correlation with serum HDL (Spearman's ρ = -0.573 and -0.529, respectively, p<0.001).

CONCLUSION

Half of the patients with cirrhosis had decompensated cirrhosis at presentation. This calls for increased awareness and strategies for earlier diagnosis of chronic liver disease and cirrhosis.

The anti-mitotic agents PTC-028 and PTC596 display potent activity in pre-clinical models of multiple myeloma but challenge the role of BMI-1 as an essential tumour gene

Future progress in the treatment of multiple myeloma (MM) requires both the characterisation of key drivers of the disease and novel, innovative approaches to tackle these vulnerabilities. The present study focussed on the pre-clinical evaluation of a novel drug class, BMI-1 modulators, in MM. We demonstrate potent activity of PTC-028 and PTC596 in a comprehensive set of in vitro and in vivo models, including models of drug resistance and stromal support. Treatment of MM cells with PTC-028 and PTC596 downregulated BMI-1 protein levels, which was found to correlate with drug activity. Surprisingly, BMI-1 was dispensable for the activity of BMI-1 modulators and MM cell growth. Our data rather point to mitotic arrest accompanied by myeloid cell leukaemia-1 (MCL-1) loss as key anti-MM mechanisms and reveal impaired MYC and AKT signalling activity due to BMI-1 modulator treatment. Moreover, we observed a complete eradication of MM after PTC596 treatment in the 5TGM.1 in vivo model and define epigenetic compounds and B cell leukaemia/lymphoma 2 homology domain 3 (BH3) mimetics as promising combination partners. These results bring into question the postulated role of BMI-1 as an essential MM gene and confirm BMI-1 modulators as potent anti-mitotic agents with encouraging pre-clinical activity that supports their rapid translation into clinical trials.

Impact of platelet turnover on long-term adverse cardiovascular outcomes in patients undergoing percutaneous coronary intervention

BACKGROUND

Increased platelet turnover and high platelet reactivity are associated with short-term major adverse cardiovascular events (MACE) after percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS) or stable coronary artery disease (SCAD). We investigated the impact of platelet turnover on long-term MACE.

METHODS

Consecutive patients presenting with ACS or SCAD undergoing PCI between 2009 and 2010 were included. All patients received clopidogrel and aspirin as dual antithrombotic therapy regimen. Multivariable Cox proportional hazard models were applied to assess the prognostic impact of platelet turnover (reticulated platelet count [RPC], mean platelet volume [MPV]) and function on long-term MACE, a composite of cardiovascular death, nonfatal myocardial infarction and nonfatal stroke.

RESULTS

In total, 477 patients were eligible. Mean age was 64.3 ± 12.7 years, 68.8% were male. Median follow-up was 5.8 (IQR 4.2-6.5) years. Median RPC was 7.6 (IQR 5.6-10.4) g/L and median MPV was 10.7 (IQR 10.1-11.3) fL. In univariable analysis, RPC was associated with MACE, both as continuous (HR 1.064 [95%CI 1.021-1.111]; P = .006) and dichotomized (HR 1.693 [95%CI 1.156-2.481]; P = .006) variable. After adjustment, continuous RPC (HR 1.055 [95%CI 1.012-1.099]; P = .010) and dichotomized RPC (HR 1.716 [95%CI 1.152-2.559]; P = .007) remained significantly associated with MACE. Neither MPV nor platelet function testing was associated with long-term adverse outcome.

CONCLUSION

Increased platelet turnover is associated with long-term adverse outcome in patients with coronary artery disease undergoing PCI. Platelet turnover represents a new marker of atherothrombotic risk and might help to guide composition or duration of antiplatelet therapy.

Twenty-four-hour time dependency of clopidogrel effects in patients with acute coronary syndromes: The CiCAD-Study

Long-term evidence shows an increased risk of cardiovascular events in the morning hours and recent studies in aspirin-treated patients have shown increased platelet reactivity at the end of the dosing interval. Similar pharmacodynamic analyses of adenosine-diphosphate (ADP) receptor inhibitors are scarce. We therefore investigated changes in clopidogrel-dependent platelet function and activation over 24 h and whether enhanced platelet turnover might explain diurnal variability of platelet function and activation. Twenty-one patients after acute coronary syndromes (ACS) on maintenance doses of clopidogrel (75 mg) and aspirin (100 mg) Once per day (OD) were included. Blood was collected at five time points in 24 h. Platelet function and activation was analyzed by vasodilator-stimulated phosphoprotein-phosphorylation (VASP-P), Verify Now, multiple electrode aggregometry (MEA), and platelet PAC-1 and P-selectin (P-sel) expression. Additionally, platelet count, mean platelet volume (MPV), and reticulated platelet fraction (RPF) were analyzed. There was significant diurnal variability of clopidogrel effects as documented with VASP-P, Verify Now, and PAC-1 and P-sel (all p < 0.05), whereas MEA did not differ over 24 h. Neither MPV nor RPF varied significantly over 24 h. In patients with high RPF, platelet function and activation was significantly higher in all assays, compared to patients with low RPF (all p < 0.05). However, the changes over time in low versus high RPF groups were similar. ADP-dependent platelet function and activation recovers significantly at the end of the 24-h dosing interval in patients with ACS on a maintenance dose of clopidogrel and aspirin. Although platelet function and activation is increased in patients with higher RPF, platelet turnover might not explain the observed diurnal variability.

Acute effect of different concentrations of cayenne pepper cataplasm on sensory-motor functions and serum levels of inflammation-related biomarkers in healthy subjects

Physical medicine therapies are often used in treating widespread musculoskeletal disorders, such as neck and low back pain. Herbal cataplasms containing rubefacient substances, such as Cayenne pepper, or galenic preparations like Munari cataplasm are commonly used as natural medications to treat painful areas. In this paper we show the effects of a 20-min application of Cayenne pepper and kaolin powder cataplasm (CPC) on healthy subjects. Treatment effects were evaluated by cold/hot feeling on visual analogue scale, blood pressure, body temperature, skin light touch sensations, two-point discrimination, and pain threshold to a mechanical stimulus, before and immediately after, 15 min after and 30 min after different concentration of Cayenne pepper in CPC preparation on healthy subjects. Maximal voluntary trunk extension force and trunk extension submaximal force matching error were also measured. In addition, the resulting optimal CPC mixture was tested for its safety by measuring changes in circulating levels of inflammatory-related biomarkers after 20-min application. The results indicate that the 5% concentration of Cayenne pepper in the preparation of CPC is the best choice, since no additional effects can be obtained with the 10% concentration, and the effects are higher than those observed at the 2.5% concentration. Importantly, 5% CPC application did not induce a significant increase of inflammatory-related biomarkers, suggesting that 20-min application has no negative side effects at systemic levels. Further studies are needed to investigate the immediate and long-term effects of repeated CPC applications as well as to understand the intersecting underlying mechanisms activated by Capsaicin and other identified factors, in order to be more extensively used in the field of physical medicine therapies.

Multiple electrode aggregometry and vasodilator stimulated phosphoprotein-phosphorylation assay in clinical routine for prediction of postprocedural major adverse cardiovascular events

Reduced antiplatelet effect of clopidogrel assessed with multiple electrode aggregometry (MEA) and vasodilator stimulated phosphoprotein-phosphorylation (VASP-P) assay has been proven to predict major adverse cardiovascular events (MACE) after coronary stenting. So far no consecutive registry has evaluated the usefulness of different adenosine diphosphate-based platelet function tests to predict outcome in unselected patients. Hence, our objective was to determine the feasibility of MEA and VASP-P for clinical routine and whether low-response to clopidogrel as determined by MEA and/or the VASP-P assays predicts MACE in a “real-life” population undergoing coronary stenting. Threehundred consecutive patients were included in this prospective registry. Blood was sampled 6–24 hours after stenting to measure MEA and VASP-P. The use of glycoprotein-IIb/IIIa-blockers limited MEA to 196 measurements. Concerning the VASP-P assay, 300 measurements were achieved. Receiver Operating Characteristics (ROC)-curves of sensitivity and specificity estimates for MACE were plotted for VASP-P assay. The area under the ROC-curve was 0.683 (p=0.014) for the platelet reactivity index (PRI) calculated from median fluorescence intensities (FI) with an optimal cut-off at 60.2% PRI. Patients above 60.2% had a significantly increased risk for MACE at six months follow-up (p=0.007). Estimating the cut-offs for the PRI from mean FI (52%) or from geometric mean FI (56.6%) led to clinically relevant differences. VASP-P assay is feasible for clinical routine to measure clopidogrel effects and to predict post-procedural MACE in unselected patients. With regard to differing cut-offs, exact standardisation of the VASP-P assay is mandatory. The use of GP-IIb/IIIa-blockers prevents MEA testing and limits its usability in unselected patients.

IKAROS expression in distinct bone marrow cell populations as a candidate biomarker for outcome with lenalidomide-dexamethasone therapy in multiple myeloma

Immunomodulatory drugs (IMiDs) are a cornerstone in the treatment of multiple myeloma (MM), but specific markers to predict outcome are still missing. Recent work pointed to a prognostic role for IMiD target genes (e.g. CRBN). Moreover, indirect activity of IMiDs on immune cells correlated with outcome, raising the possibility that cell populations in the bone marrow (BM) microenvironment could serve as biomarkers. We therefore analysed gene expression levels of six IMiD target genes in whole BM samples of 44 myeloma patients treated with lenalidomide-dexamethasone. Expression of CRBN (R = 0.30, P = .05), IKZF1 (R = 0.31, P = .04), IRF4 (R = 0.38, P = .01), MCT-1 (R = 0.30, P = .05), and CD147 (R = 0.38, P = .01), but not IKZF3 (R = -0.15, P = .34), was significantly associated with response. Interestingly, IKZF1 expression was elevated in BM environmental cells and thus selected for further investigation by multicolor flow cytometry. High IKAROS protein levels in total BM mononuclear cells (median OS 83.4 vs. 32.2 months, P = .02), CD19⁺ B cells (median OS 71.1 vs. 32.2 months, P = .05), CD3⁺ CD8⁺ T cells (median OS 83.4 vs 19.0 months, P = .008) as well as monocytes (median OS 53.9 vs 18.0 months, P = .009) were associated with superior overall survival (OS). In contrast, IKAROS protein expression in MM cells was not predictive for OS. Our data therefore corroborate the central role of immune cells for the clinical activity of IMiDs and built the groundwork for prospective analysis of IKAROS protein levels in distinct cell populations as a potential biomarker for IMiD based therapies.

Platelet turnover predicts outcome after coronary intervention

Elevated platelet turnover contributes to high platelet reactivity. High platelet reactivity after percutaneous coronary intervention (PCI) is associated with major adverse cardiovascular events (MACE). The purpose of this study was to determine the prognostic value of platelet turnover and function with regard to MACE after PCI with stent implantation. In this prospective observational study, 486 consecutive patients after PCI on aspirin and clopidogrel were included to determine platelet turnover (mean platelet volume (MPV), reticulated platelet fraction (RPF)) and platelet function (multiple electrode aggregometry (MEA), vasodilator-stimulated phosphoprotein-phosphorylation (VASP-P) assay). At six-months follow-up, MACE occurred in 10.7 % of patients. RPF (odds ratio [OR]=1.173 (95% confidence interval [CI 95 %] 1.040-1.324), p=0.009) and MPV (OR=1.459 (CI 95 % 1.059-2.008), p=0.021) were univariable predictors of MACE, whereas VASP-P (OR=1.016 (CI 95 % 1.000-1.032), p=0.052) and MEA (OR=0.999 (CI 95 % 0.980-1.017), p=0.895) failed to predict MACE. RPF remained the only platelet variable independently associated with MACE. The best model to predict MACE included: troponin I (OR=1.007 (CI 95 % 1.002-1.012), p=0.009), RPF (OR=1.136 (CI 95 % 1.001-1.288), p=0.048), CRP (OR=1.008 (CI 95 % 1.001-1.014), p=0.023) and history of myocardial infarction (OR=2.039 (CI 95 % 1.093-3.806), p=0.025). RPF (OR=1.211 (CI 95 % 1.042-1.406), p=0.012) was also independently associated with in-hospital bleedings. In conclusion, RPF as index of platelet turnover is an independent predictor of MACE and bleeding events in PCI patients on dual antiplatelet therapy. Since RPF can reliably be quantified along with routine haemograms, RPF might easily be applied in the setting of cardiovascular risk prediction.

Suppression of the noninvolved pair of the myeloma isotype correlates with poor survival in newly diagnosed and relapsed/refractory patients with myeloma

Heavy light chain (HLC) assays allow precise measurement of the monoclonal and of the noninvolved polyclonal immunoglobulins of the same isotype as the M‐protein (e.g., monoclonal IgAκ and polyclonal IgAλ in case of an IgAκ myeloma), which was not possible before. The noninvolved polyclonal immunoglobulin is termed ‘HLC‐matched pair’. We investigated the impact of the suppression of the HLC‐matched pair on outcome in 203 patients with multiple myeloma, a phenomenon that likely reflects the host's attempt to control the myeloma clone. Severe (>50%) HLC‐matched pair suppression was identified in 54.5% of the 156 newly diagnosed patients and was associated with significantly shorter survival (45.4 vs. 71.9 months, P = 0.019). This correlation was statistically significant in IgG patients (46.4 vs. 105.1 months, P = 0.017), but not in patients with IgA myelomas (32.9 vs. 54.1 months, P = 0.498). At best response, HLC‐matched pair suppression improved only in patients with ≥VGPR, indicating partial or complete humoral immune reconstitution during remission in those with excellent response. Severe HLC‐matched pair suppression retained its prognostic impact also during follow‐up after first response. In the 47 pretreated patients with relapsed/refractory disease, a similar correlation between severe HLC suppression and survival was noted (22.8 vs. not reached, P = 0.028). Suppression of the polyclonal immunoglobulins of the other isotypes than the myeloma protein correlated neither with HLC‐matched pair suppression, nor with outcome. Multivariate analysis identified severe HLC‐matched pair suppression as independent risk factor for shorter survival, highlighting the impact of isotype specific immune dysregulation on outcome in multiple myeloma. Am. J. Hematol. 91:295–301, 2016. © 2015 The Authors. American Journal of Hematology Published by Wiley Periodicals, Inc.

Prevalence of iron deficiency across different tumors and its association with poor performance status, disease status and anemia

BACKGROUND

Only limited data on the prevalence of iron deficiency (ID) and its correlation with clinical parameters are available in cancer. ID frequently contributes to the pathogenesis of anemia in patients with cancer and may lead to several symptoms such as impaired physical function, weakness and fatigue.

PATIENTS AND METHODS

Parameters of iron status and clinical parameters were evaluated in 1528 patients with cancer who presented consecutively within a four-month period at our center. One thousand fifty-three patients had solid tumors and 475 hematological malignancies.

RESULTS

ID [transferrin saturation (TSAT) < 20%] was noted in 645 (42.6%) of the 1513 patients with TSAT tests available and 500 (33.0%) were anemic. ID rates were highest in pancreatic (63.2%), colorectal (51.9%) and lung cancers (50.7%). Of the 409 iron-deficient patients in whom serum ferritin levels were available additionally to TSAT, 335 (81.9%) presented with functional ID (FID) (TSAT < 20%, serum ferritin ≥30 ng/ml) and 74 (18.1%) with absolute ID. In patients with solid tumors, prevalence of ID correlated with cancer stage at diagnosis (P = 0.001), disease status (P = 0.001) and ECOG performance status (P = 0.005).

CONCLUSIONS

ID was frequently noted in cancer and was associated with advanced disease, close proximity to cancer therapy, and poor performance status in patients with solid tumors.

Homocysteine improves risk stratification in patients undergoing endarterectomy for asymptomatic internal carotid artery stenosis

BACKGROUND AND PURPOSE

A limited life expectancy reduces the benefit from carotid endarterectomy (CEA) for treatment of asymptomatic internal carotid artery stenosis. The aim of this study was to assess homocysteine as stratifying biomarker to improve prediction of postoperative survival.

METHODS

This was a prospective, nonrandomized case series from 2003 to 2012. Two hundred and fourteen consecutive patients (<75 years, n=130; ≥75 years, n=84) undergoing CEA for their asymptomatic internal carotid artery stenosis were observed for 8.5 years for the occurrence of death after CEA as primary end point (EC-nr: 04-067-0604). Homocysteine and major cardiovascular risk factors were used for computation of prognostic indices. Cumulative survival of prognostic indices-based quintiles was estimated by Kaplan-Meier curves.

RESULTS

Total homocysteine had a significant effect on postoperative survival (P<0.0001). Total homocysteine-based quintiles of prognostic indices showed a better prediction of the survival of the patients than age alone. This caused reclassification of 17 patients (20.2%)>75 years as fit for surgery, but also indicated a high risk for 19 patients (14.6%)<75 years. In the majority (79.8%) of patients aged>75 years, statistically, CEA could not be advised because of a significantly reduced 5-year survival rate.

CONCLUSIONS

High plasma homocysteine levels suggest that older patients with asymptomatic carotid stenosis might rather benefit from intensive medical therapy than from CEA.

Vasodilator-stimulated phosphoprotein-phosphorylation assay in patients on clopidogrel: does standardisation matter?

The vasodilator-stimulated phosphoprotein-phosphorylation (VASP-P) flow-cytometric assay is mainly used in clinical trials to measure thienopyridine effects. However, there are remarkable differences in the reported optimal cut-offs, ranging from 48-61% platelet reactivity index (PRI). We therefore investigated whether a lack of standardisation might explain the differences in the cut-offs. We measured VASP-P in 62 individuals. PRI was calculated using the mean, geometric mean and median fluorescence intensities (FI). Stability of the blood-samples (time-to-assay, 0-2 days) and stability of the processed samples (0-120 minutes) within the recommended time-span were tested. Time-to-assay significantly influenced the PRI (p<0.001): the PRI from mean FI after two days was lower compared to values on day 1 (52 ± 22.9 vs. 57.7 ± 24.1, p<0.001). The PRI from the geometric mean FI after two days was lower compared to day 0 as well as day 1 (51.3 ± 23 vs. 58.2 ± 24.2 and vs. 59.1 ± 23.7, both p<0.001). The PRI from median FI was stable over time (day 0: 59.1 ± 25%, day 1: 59.7 ± 24.1% and day 2: 56.4 ± 23.9%, all p=ns). Furthermore, the lag time of the processed samples significantly altered the PRI (all p<0.001) with a maximum difference for PRI based on geometric mean FI after 90 minutes compared to baseline (Δ=3.92%PRI, p<0.001). The differences in the reported cut-offs might be explained by a lack of standardisation. More precise standardisation is inevitable, as the PRI significantly depends on the method of calculation, the time-to-assay as well as on the lag time after processing. Tolerably stable results were obtained for the PRI from the median FI.

Comparison of enoxaparin and unfractionated heparin in endovascular interventions for the treatment of peripheral arterial occlusive disease: a randomized controlled trial

BACKGROUND

Although unfractionated heparin (UFH) is an effective antithrombotic agent in endovascular interventions for the treatment of peripheral occlusive arterial disease (PAOD), it produces a highly variable anticoagulant response. Intravenous (i.v.) enoxaparin might be an effective and safe alternative.

PATIENTS AND METHODS

In a prospective, open-label, randomized, single-center trial, 210 patients with PAOD (Fontaine stage IIb to IV) were randomly assigned in a 1 (UFH): 2 (enoxaparin) fashion to receive an i.v. bolus of 60 units UFH per kg body weight or 0.5 mg enoxaparin per kg body weight, respectively, before endovascular intervention. The primary composite endpoint assessed the clinical performance of enoxaparin by comparing the peri-interventional rate of thromboembolia/occlusion (efficacy) of endovascularly reconstructed areas, of bleeding according to the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO) criteria (safety) and of any necessary re-intervention for any percutaneous transluminal angioplasty (PTA)-related bleeding. The secondary endpoint evaluated anti-factor (F)Xa levels during intervention.

RESULTS

The primary composite endpoint showed a better performance of enoxaparin (10.5% vs. 2.5% absolute difference - 8.0%; P < 0.05). The concomitant use of acetylsalicylic acid (ASA) significantly (P < 0.05) increased the risk of a complication in the UFH group, but not in the enoxaparin group. Within 15 min, anti-Xa levels were reached by 63.7% of patients treated with enoxaparin and only by 39.1% with UFH.

CONCLUSION

Enoxaparin has a better performance than UFH in endovascular interventions for the treatment of PAOD. In patients with concomitant use of ASA, the risk of complications with UFH increases significantly compared with enoxaparin.

N-terminal pro B-type natriuretic peptide (NT pro-BNP) is a predictor of long-term survival in male patients of 75 years and older with high-grade asymptomatic internal carotid artery stenosis

BACKGROUND

Carotid endarterectomy (CEA) is commonly performed for asymptomatic high-grade internal carotid artery (ICA) stenosis to prevent stroke. However, despite advancing age of the society, for patients older than 75 years, there is no recommendation by the European guidelines for CEA, as this age group might not benefit from this intervention due to a limited life expectancy.

OBJECTIVE

We assessed N-terminal pro B-type natriuretic peptide (NT pro-BNP) as a predictive marker for long-term survival in this particular patient population in order to stratify patients for an improved surgical outcome.

METHODS

In a nonrandomized single-center clinical trial, we prospectively studied mortality rates of 205 consecutive patients (80 women, 125 men; mean age, 75 ± 10 years) with asymptomatic high-grade ICA stenosis in relation to preoperative plasma NT pro-BNP levels. We estimated cumulative survival over 5 years by Kaplan-Meier curves and established a proportional hazard-model by Cox regression.

RESULTS

In male patients, higher levels of preoperative NT pro-BNP levels were associated with a significantly increased long-term mortality. Those 75 years or older had the same survival rate as younger patients, if NT pro-BNP levels were low, making them thus eligible for CEA.

CONCLUSIONS

The results of our study suggest that preoperative plasma levels of NT pro-BNP are a valuable tool for the stratification of male patients. Male patients older than 75 years with low levels of NT pro-BNP should be referred for carotid revascularization, as they will most likely enjoy the benefit of surgery.

Effects of enoxaparin and unfractionated heparin on platelet activity and reactivity during carotid endarterectomy

The aim of this study was to determine platelet activity and reactivity and the effects of unfractionated heparin (UFH) and enoxaparin on platelet function during carotid eversion endarterectomy under local anesthesia. Twenty symptomatic patients undergoing carotid endarterectomy were randomly assigned to either 5,000 units of UFH or body weight-adjusted enoxaparin (0.5 mg/kg body weight) as an intraoperative intravenous bolus. The activity of platelets was assessed by measuring the expression of CD62p and CD41 with flow cytometry. Additionally, platelet-leukocyte aggregates (PLAs) were enumerated. The reactivity of platelets was evaluated by measuring the expression of the same antigens after stimulation. In addition, platelet reactivity was also analyzed using a PFA-100 analyzer. A significant increase in platelet activity was observed during surgery for CD41 and CD62p (p = .002 and < .001, respectively). The number of PLAs showed no significant changes during surgery. Yet there was a significant difference between patients treated with UFH and patients treated with enoxaparin. No difference for platelet activity or reactivity for patients receiving either UFH or enoxaparin prior to cross-clamping of the carotid arteries was seen. The formation of PLAs after endarterectomy was significantly higher in the UFH group; thus, PLAs are probably a useful surrogate parameter for measuring platelet activity.

Rituximab treatment provides no clinical benefit in patients with pretreated advanced multiple myeloma

In the present phase II study, we tested the efficacy of a single course of rituximab (375 mg/m2 on days 1, 8, 15 and 22) as treatment for relapsed myeloma. The rationale for this study was the identification of a population of clonotypic CD20+ B cells that are believed to be precursors of malignant plasma cells. In addition, CD20 was expressed on 10% and 50% of bone marrow plasma cells in two of the ten patients enrolled. Following rituximab treatment, none of the patients achieved an objective response. Two patients had stable disease at month 6, the predefined end of the study, while, at that time, two patients were classified as having progressive disease. One patient opted to withdraw from the study at month 3, at which time he had stable disease. The other five patients had to be withdrawn early from the post-treatment observation because of need of salvage therapy for progressive disease. WHO grade <or=2 toxicity was seen in four patients. Peripheral B cells significantly decreased at 3 months, while no significant change of bone marrow myeloma cells was noted at that time. Mean paraprotein levels increased slightly during follow-up but IgM levels dropped in all patients, indicating an effective targeting of normal, short-lived plasma cells. Taken together, rituximab treatment yielded significant reductions in circulating B cells and serum IgM levels but had no beneficial clinical effect.

Aspirin resistance among long-term aspirin users after carotid endarterectomy and controls: Flow cytometric measurement of aspirin-induced platelet inhibition

BACKGROUND

Numerous studies have indicated that some patient subpopulations do not respond to the antithrombotic effects of aspirin. The objective of this study was to evaluate aspirin-induced inhibition of platelet cyclooxygenase (COX) using a flow cytometric technique in long-term aspirin users after carotid endarterectomy (CEA) and controls with newly diagnosed carotid stenosis not taking aspirin and to compare these results with platelet function analyzer measurements.

METHODS

The study included 86 patients with a history of CEA on long-term aspirin therapy (100 mg daily) and 29 age-matched patients with newly diagnosed carotid artery stenosis not taking aspirin. Platelet-rich plasma diluted with phosphate-buffered saline was incubated with arachidonic acid (ARA) at a final concentration of 80 micromol/L. After staining with phycoerythrin-labeled anti-P-selectin (CD62p) antibody, platelet CD62p-antigen expression was measured on a flow cytometer.

RESULTS

Flow cytometric measurement of ARA-induced platelet activation showed an inhibition of ARA-induced platelet stimulation in all patients on aspirin therapy, whereas all but two controls (95%) showed expected platelet reactivity. In contrast, results of the platelet function analyzer measurements were normal in 16% of aspirin-treated patients.

CONCLUSIONS

Flow cytometric measurement of CD62p expression on platelets after incubation with ARA proved to be a practicable tool to monitor aspirin-induced inhibition of platelet COX. Results in patients on long-term low-dose aspirin therapy show that the inability of aspirin to inhibit platelet COX for both symptomatic and asymptomatic patients with high-grade internal carotid artery stenosis is a very rare event. So-called aspirin resistance detected quite frequently by platelet function analyzer measurement is most likely from COX-independent mechanisms.

Assessing aspirin-induced attenuation of platelet reactivity by flow cytometry

INTRODUCTION

Certain patient subpopulations do not respond to antithrombotic effects of aspirin and different approaches have been proposed to detect and define this so-called aspirin resistance. In this study, a methodological and clinical evaluation of a flow cytometric method for the detection of aspirin-induced inhibition of platelet cyclooxygenase (COX) is presented.

MATERIALS AND METHODS

Platelet CD62p-antigen (P-selectin) expression was determined by flow cytometry after incubating diluted platelet rich plasma (PRP) with arachidonic acid (ARA). After establishing the method's technical characteristics, it was used to investigate 114 individuals (70 patients with atherosclerotic vascular disease under long-term medication of 100 mg aspirin daily, 29 age-matched patients with vascular disease without anti-platelet medication and 15 healthy volunteers). Data were compared to those obtained by the PFA-100 platelet function analyzer.

RESULTS

Imprecision was between 3.3% and 13%. Sample storage at room temperature increased baseline activity of platelets already after 2 h. After ARA stimulation, the proportion of CD62p-positive platelets was considerably lower in aspirin-treated patients than in controls (median [lower-upper quartile]: 4% [3-6] vs. 50% [29-68], p<0.001). Only one aspirin-treated patient (1.5%) showed normal reactivity to ARA. In contrast to flow cytometry, PFA-100 analysis yielded normal results in 17% of aspirin-treated patients.

CONCLUSIONS

The presented flow cytometric method can be used to monitor aspirin-induced inhibition of platelet COX. Aspirin resistance defined as failure to inhibit platelet COX is a rare phenomenon suggesting that most cases of aspirin resistance detected using the PFA-100 are caused by COX-independent mechanisms.

Homocysteine and Early Re-stenosis after Carotid Eversion Endarterectomy

BACKGROUND

Homocysteine (Hcy) appears to be involved in the development of intimal hyperplasia and arterial thrombosis. The purpose of this study was to evaluate the association of plasma Hcy with early re-stenosis following carotid eversion endarterectomy.

PATIENTS AND METHODS

Of 398 consecutive patients, 363 were included in this study. 62% of patients had symptomatic internal carotid artery (ICA) stenosis. Patients had preoperative assessment of Hcy and other well established atherosclerosis risk factors. Intraoperatively, completion angiography was performed in 2 planes. Patients had clinical, Hcy and duplex follow up at 1, 3, 18 and 36 months postoperatively.

RESULTS

Complete follow up data were available for 312 patients. Five patients suffered from strokes and 2 patients died during the peri-operative period (combined stroke and death rate of 2%). Mean follow up was 26+/-5 months (range 17 to 36 months). Seventeen and six patients (5.5%) developed a 50-69% and >70% re-stenosis, respectively. Serum creatinine was significantly higher in patients with early re-stenosis, occlusion or stroke after CEA (P=0.043). High grade re-stenosis, occlusion and stroke ipsilateral to the operated side (17 patients) was associated with HbA1C and creatinine (P=0.043 and 0.046, respectively) but not Hcy.

CONCLUSION

While Hcy is a recognized independent risk factor for atherothrombosis, our study suggests that there is no association of Hcy with early re-stenosis after eversion endarterectomy.

Plasma D-lactate as a potential early marker for colon ischaemia after open aortic reconstruction

BACKGROUND AND AIM

The breakdown of mucosal barrier function due to intestinal hypo-perfusion is the earliest dysfunction of ischaemic colitis. Severe colon ischaemia after aortic reconstruction is associated with mortality rates up to 90%. Therefore, early detection and treatment of patients with extensive ischaemic colitis is of crucial importance. In experimental studies, both D-lactate and bacterial endotoxin have been reported as markers of intestinal mucosal barrier impairment. However, evidence of their value in clinical practice is lacking. The aim of this pilot prospective cohort study was to assess the association between ischaemia of the colon (assessed histologically) and plasma levels of D-lactate and endotoxin in patients undergoing open aortic reconstruction.

PATIENTS AND METHODS

Twelve consecutive patients underwent surgery between February and April 2003. Six patients underwent emergency surgery and six patients elective aortic surgery. D-Lactate and endotoxin levels were measured in blood samples collected according to a standardised protocol. For histological examination biopsies were obtained by sigmoidoscopy on days 4-6 after surgery, or earlier if indicated clinically.

RESULTS

As early as 2 h postoperatively, elevated plasma levels of d-lactate were measured in patients with histologically proven ischaemic colitis. The peak of D-lactate elevation was on postoperative days 1 and 2. Concentration of plasma endotoxin was not significantly different in patients with or without ischaemic colitis.

CONCLUSION

Our data suggest that plasma D-lactate levels are a useful marker for early detection of ischaemic colitis secondary to aortic surgery.

Carotid Endarterectomy Under Local Anaesthesia does not Increase Plasma Homocysteine Concentration

INTRODUCTION

The purpose of this cohort study was to evaluate the effect of carotid endarterectomy under local anaesthesia on homocysteine (Hcy) concentrations.

PATIENTS AND METHODS

Of 100 patients with internal carotid artery (ICA) stenosis >70%, the complete data set was available for 91 patients (39 asymptomatic and 52 symptomatic). All patients underwent eversion endarterectomy of the ICA under regional anaesthesia.

RESULTS

Thirty-two percent of the examined patients had a total Hcy above 15 micromol/l. The mean Hcy levels preoperatively were 13.9+/-4.8 micromol/l. The Hcy levels on day 5 were 13.1+/-5.0 micromol/l and after 6 months 14.0+/-5.8 micromol/l. There was no significant change during follow-up. No intraoperative strokes and deaths were observed and during the 6 months follow-up no recurrent strokes, TIAs or deaths occurred.

CONCLUSION

Patients undergoing carotid endarterectomy under regional anaesthesia do not have an increase in total Hcy postoperatively. This finding is in contrast to results from cardiac surgery and carotid endarterectomy in a recently published animal study, both performing surgery under general anaesthesia.

Chromosomal aberrations are shared by malignant plasma cells and a small fraction of circulating CD19+ cells in patients with myeloma and monoclonal gammopathy of undetermined significance

In the present study, we aimed to identify distinct structural and numerical chromosomal aberrations in peripheral blood B cells of patients with myeloma and monoclonal gammopathy of undetermined significance (MGUS), which reflect changes thought to occur at different stages of the disease process. Peripheral blood from 12 patients with multiple myeloma and three patients with MGUS was investigated for the occurrence of retinoblastoma-1 gene deletions, p53 gene deletions and numerical aberrations demonstrated previously to be present in the patients' bone marrow CD138+ cells. By combining immunocytochemical staining for light chains and interphase fluorescence in situ hybridization (FISH), aberrant light-chain +ve cells were detected in the circulating CD19+ cell fraction. Each kind of chromosomal change present in the myeloma tumour cells was found to be shared by a small fraction of CD19+ cells (0.1-1.8%; median 0.36%, n = 6). In one MGUS patient, aberrant cells could be identified with a frequency of 0.34% within the CD19-sorted cell fraction. Clonotypic cells were detected with a frequency of 0.01-0.07% of peripheral blood nucleated cells by m-RNA in situ hybridization with patient-specific probes in three investigated patients. These results provide evidence that the circulating clonotypic B cells are closely related to the malignant plasma cells in myeloma and MGUS.

Immunofluorescence assays (IFA) and enzyme-linked immunosorbent assays (ELISA) in autoimmune disease diagnostics--technique, benefits, limitations and applications

Autoimmune diseases are relatively frequent disease complexes, affecting approximately five to seven percent of the population. After cardio-vascular and malignant diseases they come third in mortality. As the clinical diagnosis of rheumatic autoimmune diseases is difficult, laboratory tests are helpful in differential diagnosis and for verification of the clinical diagnosis. The most commonly used assay is the determination of ANAs (anti nuclear antibodies) by indirect immunofluorescence (IFA). However, this method lacks reliable standardisation and is very dependable on the qualification of the observer. Enzyme Immunoassays (EIA) and Immunoblotting techniques, on the contrary, attain good standardisation and comparability. However, the latter methods are limited to the presentation of defined autoantibodies only. There is a need to select a suitable strategy for the use of laboratory parameters in order to support the clinical diagnosis more efficiently. A possible strategy is to replace IFA as a first line screening-step by second-generation ANA-EIA kits.

A simple method for measurement of CD14weak CD16strong monocytes in peripheral blood

Mounting evidence for the clinical significance of the CD 14weak CD16strong monocyte subpopulation in peripheral blood induced the demand for an efficient method for its determination. We propose a simple, fast, no-wash flow cytometric method using fluorescence-labelled anti-CD14, anti-CD16, and anti-HLA-DR antibodies and ammonium chloride-based erythrocyte lysis. This type of analysis can be performed on a standard three-colour flow cytometer. The method avoids interference by NK-cells and neutrophil granulocytes without defining monocytes by stringent light scatter criteria that might lead to a loss of CD14weak CD16strong monocytes. It, therefore, offers high reliability and accuracy. Its performance recommends the method to be used for routine clinical measurements of CD14weak CD16strong monocytes.

Differential expression of tumor necrosis factor receptor subtypes on leukocytes in systemic inflammatory response syndrome

OBJECTIVE

To determine the expression of tumor necrosis factor (TNF) receptor in patients with systemic inflammatory response syndrome (SIRS).

DESIGN

Prospective study.

SETTING

Intensive care unit and central laboratory.

PATIENTS

Blood specimens from 18 healthy volunteers (controls) and 16 patients with SIRS.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Using monoclonal antibodies, fluorescence labeling, and high sensitivity flow cytometry, we measured the expression of membrane TNF receptor subtypes TNF-R55 and TNF-R75 on peripheral blood leukocytes. Receptor expression is expressed as mean fluorescence intensity +/- SD (units: detection channel number). In controls, TNF-R55 was only weakly expressed (monocytes: 2.5+/-1.8; neutrophils: 0.7+/-0.8), whereas expression of TNF-R75 was higher (monocytes: 28.6+/-9.0; neutrophils: 4.8+/-1.0) and was also found on lymphocytes (on CD8+ lymphocytes: 5.7+/-1.8; CD16+: 5.5+/-1.2; CD4+: 9.7+/-3.7). In SIRS, we observed increased expression of TNF-R55 on monocytes (6.9+/-3.4, p<.001) and neutrophils (2.2+/-1.9, p<.01), as well as decreased expression of TNF-R75 on monocytes (17.3+/-13.2; p<.001). The extent of TNF-R55 up-regulation did not correlate with that of TNF-R75 down-regulation. TNF-R55 on monocytes and neutrophils strongly correlated with body temperature but not with survival, whereas monocyte TNF-R75 was considerably lower in nonsurvivors, albeit not significantly (12.3+/-7.1 vs. 23.9+/-16.7; p = .07).

CONCLUSIONS

These data indicate that leukocyte TNF-R55 and TNF-R75 react differentially and probably serve different functions in SIRS, which prompts the investigation of receptor subtype-specific therapeutic approaches.

Measurement of absolute concentration and viability of CD34+ cells in cord blood and cord blood products using fluorescent beads and cyanine nucleic acid dyes

Conventional flow cytometric methods for CD34+ cell counting may be affected by the high number of nucleated red blood cells or nonviable cells in cord blood and its products. We developed a simple flow cytometric no-wash procedure that avoids these shortcomings because it provides absolute CD34+ cell counts and assesses cell viability. Samples were incubated with phycoerythrin (PE)-labeled anti-CD34 (Becton Dickinson Immunocytometry Systems [BD], San Jose, CA) and peridinin chlorophyll protein (PerCP)-labeled anti-CD45 (BD) in bead-containing TRUCOUNT tubes (BD). After red cell lysis with a fixative-free reagent, the impermeant nucleic acid dye YO-PRO-1 (Molecular Probes, Eugene, OR) was added and samples were analyzed on a single-laser FACSCalibur (BD). A comparison with the ProCOUNT progenitor cell assay (BD) in 57 samples revealed excellent correlation of results (r = 0.98, intercept -0.2 cells/microl, slope 1.01). Precision studies conveyed coefficients of variation of 6.4 and 8.9% at concentrations of 35 and 16 CD34+ cells/microl, respectively. In untreated and leukocyte-enriched cord blood 4.5+/-3.8% of CD34+ cells were stained by YO-PRO-1, representing apoptotic or necrotic cells. In post-thawing cryopreserved samples this number increased to 10.4+/-5.5%. Isotype controls showed very low blank values of viable cells (0.1+/-0.4 cells/microl, maximum 2.4) and seemed unnecessary. We found no washing-related alteration of results in 35 samples, indicating that the method may also be performed with cell washing. Replacing YO-PRO-1 with TO-PRO-3 facilitated four-color analysis of subpopulations of viable CD34+ cells on a FACSCalibur equipped with a second (diode) laser. We found the proposed method to be a rapid, efficient, and flexible procedure that improved validity of CD34+ cell counts.

FMC7 antigen expression on normal and malignant B-cells can be predicted by expression of CD20

Most antibody panels proposed for flow cytometric immunophenotyping of non-Hodgkin's lymphomas and chronic lymphoid leukemias include anti-CD20 and FMC7 antibodies. As in our experience, reactivity of B-cells with these antibodies seemed to be correlated, we evaluated whether the simultaneous use of anti-CD20 and FMC7 antibodies is justified. Using flow cytometry, we measured the binding of these 2 antibodies to the B-cells of 67 bone marrow aspirates, 31 lymph node biopsies, 18 peripheral blood specimens, and 12 tissue samples from other locations. The diagnoses included 50 cases without overt abnormalities, 5 reactive lymphadenopathies, 56 lymphomas and chronic lymphoid neoplasias, and 17 cases with other malignancies. Although CD20 expression was consistently higher, we observed a significant and strong correlation between CD20 and FMC7 antigen expression on B-lymphocytes, irrespective of the nature of the sample or disease (r=0.910; P < 0.001). Moreover, FMC7 antigen expression on B-cells could be predicted by CD20 expression with a sensitivity of 96%, a specificity of 94% and an efficiency of 96%. Our results show that although differing in intensity, expression of CD20 on B-cells closely parallels that of FMC7 antigen. We, therefore, conclude that little additional information is revealed by using FMC7 in immunophenotyping of non-Hodgkin's lymphomas or chronic lymphoid leukemias if intensity of CD20 expression is taken into consideration.

Toward a new reference method for the leukocyte five-part differential

A flow cytometric method performing a five-part leukocyte differential based on three-color staining with anti-CD45-fluorescein isothiocyanate (FITC), anti-CD-14-phycoerythrin (PE)/Cy5, and a cocktail of PE-labeled anti-CD2, anti-CD16, and anti-HLA-DR antibodies was evaluated. Results obtained by using three different sample preparation procedures and two different flow cytometers were compared with those of a 1,000-cell manual differential for evaluation of accuracy. We observed excellent correlations with the manual differential for all leukocyte subclasses and even higher correlations between the different flow cytometric methods. Flow cytometric basophil results were identical to the manual counts, regardless of which sample preparation technique or flow cytometer was used. Therefore, we propose our flow cytometric method as the first acceptable automated reference method for basophil counting. The flow cytometric results for the other leukocyte subclasses were apparently influenced by the sample preparation, which could not be explained by cell loss during washing steps. Moreover, a small influence of the flow cytometer was also observed. Assessing the influence of sample storage, we found only minimal changes within 24 h. In establishing reference values, high precision of flow cytometric results facilitated detection of a significantly higher monocyte count for males (relative count: 7.08 +/- 1.73% vs. 6.44 +/- 1.33%, P < 0.05; absolute count: 0.536 +/- 0.181 x 10(9)/liter vs. 0.456 +/- 139 x 10(9)/liter, P < 0.01). Our data indicate that monoclonal antibody-based flow cytometry is a highly suitable reference method for the five-part differential: It also shows, however, that studies will have to put more emphasis on methodological issues to define a method that shows a high interlaboratory reproducibility.

Value of neutrophil CD16 expression for detection of left shift and acute-phase response

Fc gamma RIII (CD16) expression of neutrophil granulocytes was measured in 156 patients by means of fluorescence-labeled antibodies with a flow cytometer. Results were compared with (1) 400-cell manual differential count; (2) left shift flagging on hematology analyzers; (3) absolute neutrophil count; and (4) acute-phase protein levels. Asynchrony was noted between neutrophil CD16 expression and microscopically defined neutrophil stage, particularly in heavily left-shifted samples, which made it impossible to reliably enumerate immature neutrophils on the basis of CD16 expression. According to receiver operating characteristics, the absolute count of CD16-negative neutrophils was highly discriminatory for detection of left shift, with an area under the curve (AUC) of 0.842 +/- 0.03 (SE) and maximum efficiency of 81% +/- 3%, but absolute neutrophil count was not significantly inferior (0.821 +/- 0.03 and 76% +/- 3%). STKS and SE9000 flagging demonstrated efficiency of 76% +/- 3% and 81% +/- 3%, respectively. For detection of acute-phase response, absolute neutrophil count (AUC, 0.836 +/- 0.04; maximum efficiency, 80% +/- 4%) outperformed both quantitative neutrophil CD16 expression (0.760 +/- 0.05; 75% +/- 4%) and absolute CD16-negative neutrophil count (0.757 +/- 0.05; 71% +/- 4%); absolute band count performed similarly (0.853 +/- 0.04; 79% +/- 4%) and showed high efficiency at high sensitivity and specificity. Efficiency of analyzer flagging for detection of acute-phase response was not superior to absolute neutrophil count (STKS, 77% +/- 4%; SE9000, 78% +/- 4%). In conclusion, the diagnostic value of measuring neutrophil CD16 expression was generally similar to that of less complicated analytes.

Increased serum levels of soluble CD44-isoform v5 in rheumatic diseases are restricted to seropositive rheumatoid arthritis

Serum levels of sCD44v5 were measured in 134 patients with definite inflammatory rheumatic diseases (IRD) using a sandwich type ELISA. 94 patients suffered from erosive IgM-rheumatoid factor positive rheumatoid arthritis (RA+), 20 with undifferentiated seronegative polyarthritis, 12 with osteoarthropathia psoriatica and psoriasis vulgaris, 3 with systemic lupus erythematosus, 3 with scleroderma and 2 with reactive arthritis. Elevated serum levels (> 58 ng/ml to 221 ng/ml; median: 93 ng/ml) were only detected in 54/94 (57%) patients with RA+, but not in other IRD. They correlated with advanced stages of disease (Steinbrocker stages III + IV; p < 0.05), elevated CRP-levels (p < 0.01) and higher measurements of IgM rheumatoid factor.

Use of precision profiles to evaluate precision of the automated leukocyte differential

The commonly used methods of assessing the precision of the automated leukocyte differential have certain drawbacks that affect the validity and comparability of results. In the present report, we introduce a procedure based on building precision profiles from a large number of within-run imprecision experiments. The profiles are fitted to the function for the CV of proportions, which yields the number of theoretically differentiated leukocytes. Differences between fitted curves are evaluated for statistical significance by the F-test. As an example, we compared the precision of two hematology analyzers, a flow-cytometric technique involving fluorescence-labeled monoclonal antibodies, and the manual differential. We were able to establish definite differences in precision between different analyzers and different leukocyte classes. Our data also indicated that conventional within-run imprecision studies may completely misjudge analyzer precision. Furthermore, we could demonstrate that the precision of analyzers that analyze a fixed amount of blood rather than a fixed number of leukocytes is strongly influenced by the leukocyte count of the sample, leading to high imprecision for leukopenic samples. We believe the proposed procedure is a useful addition to currently used protocols; it yields clear results and creates a statistical basis of comparison between various instruments and techniques of differentiation.

Use of precision profiles to evaluate precision of the automated leukocyte differential

The commonly used methods of assessing the precision of the automated leukocyte differential have certain drawbacks that affect the validity and comparability of results. In the present report, we introduce a procedure based on building precision profiles from a large number of within-run imprecision experiments. The profiles are fitted to the function for the CV of proportions, which yields the number of theoretically differentiated leukocytes. Differences between fitted curves are evaluated for statistical significance by the F-test. As an example, we compared the precision of two hematology analyzers, a flow-cytometric technique involving fluorescence-labeled monoclonal antibodies, and the manual differential. We were able to establish definite differences in precision between different analyzers and different leukocyte classes. Our data also indicated that conventional within-run imprecision studies may completely misjudge analyzer precision. Furthermore, we could demonstrate that the precision of analyzers that analyze a fixed amount of blood rather than a fixed number of leukocytes is strongly influenced by the leukocyte count of the sample, leading to high imprecision for leukopenic samples. We believe the proposed procedure is a useful addition to currently used protocols; it yields clear results and creates a statistical basis of comparison between various instruments and techniques of differentiation.

Proposed reference method for peripheral-blood monocyte counting using fluorescence-labelled monoclonal antibodies

Flow cytometry using fluorescence-labelled monoclonal antibodies has been proposed as a possible new reference method to evaluate the monocyte counting performance of automated hematology analyzers. Since in previous studies only one such technique was applied, we investigated how different flow cytometric techniques compared to the manual differential and a hematology analyzer. Relative monocyte counts of 60 samples of the daily routine were determined on a Coulter Profile II flow cytometer after incubation with two different CD45-FITC/CD 14-PE antibody combinations and subsequent preparation with two whole-blood lysis techniques, including one no-wash technique. Results were compared to those of a 600-cell manual differential and to those of the Coulter STKS hematology analyzer. All flow cytometric methods correlated very well with the manual differential (r > or = 0.925) and none showed a significant bias. The Coulter STKS relative monocyte counts were slightly higher than those of the manual differential (8.76% vs. 8.18%). The correlations between the methods employing monoclonal antibodies were excellent (r > or = 0.995) and the mean monocyte counts identical although a small, non-systematic influence of sample preparation techniques was noted. An influence of the antibody clones was not observed. The precision of the Profile II results was far superior to that of the manual differential and the STKS. Our data show that flow cytometry employing fluorescence-labelled monoclonal antibodies is a potentially ideal new reference method for monocyte counting. However, they also show that establishing a new reference method will require extensive investigation and exact definition of the sample preparation procedure to be used.

Evaluation of automated basophil counting by using fluorescence-labelled monoclonal antibodies

The shortcomings of current methods of basophil enumeration detract from the clinical value of the basophil count. Moreover, sophisticated and costly techniques of automated basophil counting hardly can be validated for lack of a suitable reference method. We investigated whether a flow cytometric technique using double staining with fluorescence-labelled monoclonal antibodies (mAb) CD45-FITC and CD14-PE on a Coulter Epics Profile II could be used to evaluate basophil counting performance of hematology analyzers. The technique was compared with the 800-cell manual differential, the Coulter STKS, and the Cobas Argos 5 Diff. Precision: STKS, Argos and Profile II showed a precision analogous to a 2,173, 2,250-, and 14,705-cell differential, respectively, illustrating the superiority of automated methods. Accuracy (150 normal and abnormal samples): Using the Profile II as reference the STKS showed a notably weaker correlation than the Argos (r = 0.581 and 0.718, respectively), although this difference was nearly concealed when the imprecise manual differential served as reference (r = 0.517 and 0.562, respectively). The Profile II correlated relatively well with the manual differential (r = 0.730). Analyzing 137 healthy adult subjects, we obtained a reference range of 0.33 to 1.35% (0.020 to 0.102 x 10(9) basophils/L) for the mAb-based method. These data would recommend mAb-based basophil counting as a valuable tool for instrument evaluation. However, an observed bias of 0.09% against the manual differential suggests that modifications are necessary before this technique can be considered as new reference method.

Peripheral blood monocyte counting: towards a new reference method

Flow cytometric enumeration of monocytes stained with fluorescence-labelled monoclonal antibodies has been proposed as a possible reference method for monocyte counting. We compared precision and accuracy of monocyte counting of the Coulter STKS, the Cobas Argos 5 Diff, the 800-cell manual differential, and the Coulter Epics Profile II flow cytometer using double-staining with fluorescence-labelled monoclonal antibodies (CD45-FITC and CD14-PE). Precision: STKS, Argos and Profile II achieved a precision analogous to a 3423-, 1298-, and 11089-cell differential, respectively, confirming the superiority of automated methods. Accuracy (136 normal and abnormal samples): Correlation of automated methods with the manual differential was good (STKS: r = 0.934, Argos 5 Diff: r = 0.808, Profile II: r = 0.924; Spearman's rank correlation coefficient). The mean relative STKS monocyte result was 0.52 +/- 1.63% (mean +/- SD) higher than the manual differential, whereas the Argos 5 Diff results were 1.22 +/- 2.51% lower (p < 0.001). Profile II results showed a small bias against the manual differential (-0.18 +/- 1.44%, p < 0.05). Analysing 135 healthy adult subjects on the Profile II, males were found to have a higher mean monocyte count (relative count: 6.95 +/- 1.43% vs. 5.86 +/- 0.98%; absolute count: 0.48 +/- 0.15 x 10(9)/l vs. 0.39 +/- 0.11 x 10(9)/l, p < 0.001) and a higher and wider normal range than females (relative count: 4.97 to 9.78% vs. 4.26 to 7.81%, absolute count: 0.30 to 0.84 x 10(9)/l vs. 0.25 to 0.65 x 10(9)/l). Flow cytometry based on fluorescence-labelled monoclonal antibodies for monocyte enumeration seems an efficient tool to evaluate the monocyte counting performance of haematology analysers and an ideal successor to the manual differential as reference method for monocyte counting.

Utilization of tyrosine-containing dipeptides and N-acetyl-tyrosine in hepatic failure

The impact of hepatic dysfunction on the elimination and hydrolysis of three potential tyrosine sources for total parenteral nutrition, the dipeptides L-alanyl-L-tyrosine (Ala-Tyr) and glycyl-L-tyrosine (Gly-Tyr), and N-acetyl-L-tyrosine (Nac-Tyr) were evaluated in six patients with hepatic failure (five chronic, one acute) and seven healthy subjects. In controls, whole-body clearance (Cltot) of Ala-Tyr was higher than of Gly-Tyr (3,169 +/- 214 vs. 1,780 +/- 199 mL/kg/min, P < .01), and both exceeded clearance of Nac-Tyr (309 +/- 29 mL/kg/min, P > .01). Both dipeptides were hydrolyzed and released tyrosine immediately. In hepatic failure, elimination and hydrolysis of Ala-Tyr and Gly-Tyr were comparable to controls, but Cltot of Nac-Tyr was reduced (236 +/- 26 mL/kg/min). Neither in controls nor in patients an increase in plasma tyrosine concentration was seen after Nac-Tyr, and the major part of Nac-Tyr infused was lost in urine. The Cltot of tyrosine as evaluated after Ala-Tyr infusion (with the immediate release of tyrosine) was severely reduced in hepatic failure (152.7 +/- 38.4 vs. 484.4 +/- 41.4 mL/kg/min, P < .001) and half-life (kle) was retarded from 14.4 +/- 1.4 to 90.2 +/- 32.2 minutes (P < .03). The authors conclude that acute and chronic hepatic dysfunction does not affect elimination and hydrolysis of the dipeptides Ala-Tyr and Gly-Tyr and the constituent amino acids are released immediately. Nac-Tyr elimination was not grossly affected by hepatic failure, but neither in healthy subjects nor in hepatic failure patients was an increase of tyrosine seen. Both dipeptides but not Nac-Tyr may serve as a tyrosine source in parenteral nutrition. Moreover, by its rapid hydrolysis, the use of Ala-Tyr, for the first time, enables a simple rapid nonisotope evaluation of tyrosine kinetics for assessment of liver function.

Precision and accuracy of monocyte counting. Comparison of two hematology analyzers, the manual differential and flow cytometry

The Coulter STKS (Coulter, Hialeah, FL), the Abbott CD3500 (Abbott Diagnostics, Abbott Park, IL), a 400-cell manual differential, and flow cytometry using double-staining with fluorescence-labelled monoclonal antibodies (CD45-FITC and CD14-PE) on a Coulter Epics Profile II were evaluated for precision and accuracy in relative monocyte counting. STKS, CD3500, and Profile II achieved a precision analogous to a 3,542-, 1,835-, and 11,998-cell differential, respectively, demonstrating the superiority of automated methods. Analysis of 156 normal and abnormal samples revealed that the mean relative monocyte counts of the manual differential, CD3500 and Profile II were not significantly different. Only the STKS results showed a positive bias (0.79% +/- 1.65), which was increased in lymphocytic samples. Linear regression between the Profile II as independent viable, and the other techniques yielded acceptable correlation coefficients (STKS: 0.861, CD3500: 0.844, manual differential:0.833). Profile II results were also compared to those of a Becton Dickinson FACScan (Becton Dickinson, Mountain View, CA), which yielded an excellent correlation (r = 0.991) but a slightly smaller relative monocyte count (bias-0.39% +/- 0.60) of the latter. On the basis of these data, the authors recommend the use of monoclonal antibodies as a new reference method, but also indicate the need for further methodological investigations.

Importance of liver and kidney for the utilization of glutamine-containing dipeptides in man

The impact of hepatic and renal failure on the metabolism of L-alanyl-L-glutamine (Ala-Gln) and glycyl-L-glutamine (Gly-Gln) was investigated in 11 healthy volunteers, five patients with liver cirrhosis, and six patients with chronic renal failure. The clearance (mL.kg-1.min-1) of Ala-Gln was significantly higher than that of Gly-Gln in all three groups. Renal failure significantly reduced clearances of both Ala-Gln and Gly-Gln (13.27 +/- 0.71 and 3.06 +/- 0.28) when compared with control values (21.68 +/- 1.21 and 7.08 +/- 0.38). Liver failure had no significant influence on the clearances of Ala-Gln and Gly-Gln (22.62 +/- 2.89 and 6.20 +/- 0.88). Liver failure delayed and renal failure almost abolished the increases in plasma concentrations of free amino acid residues after peptide injection. It is concluded that other organs can substitute for the peptide-clearing function of the liver, but not of the kidney. Kidney is the most important organ for the clearance of dipeptides and the release of amino acid residues into circulation. Our data show that clearance rates of both Ala-Gln and Gly-Gln are sufficient to avoid accumulation of either peptide if infused in the presently recommended doses. Both Ala-Gln and Gly-Gln could therefore be used as sources for glutamine in parenteral nutrition even in patients with chronic renal failure.