Olav Klingenberg

Discrepancy between tissue factor activity and tissue factor expression in endotoxin-induced monocytes is associated with apoptosis and necrosis

Tissue factor (TF), the main initiator of blood coagulation, contributes to the manifestation of disseminated intravascular coagulation following septic shock in meningococcal infection. Since a direct relationship between disease severity and lipopolysaccharide (LPS) concentration in the circulation has been shown, we hypothesized that the procoagulant and cytotoxic effects of endotoxin also in vitro were related to its concentration. In vitro studies, however, have frequently used much higher LPS concentrations than those observed in clinical samples. Using elutriation-purified human monocytes, we observed that LPS up to 1000 ng/ml exerted a concentration-dependent increase in TF activity (tenase activity, fibrin formation in plasma). Although there was a dose-dependent increase in TF activity, there was not a concomitant increase in TF expression at LPS concentrations above 1 ng/ml (flow cytometry, Western blotting, TF mRNA). Flow cytometry revealed that this discrepancy between TF activity and TF expression at endotoxin concentrations above 1 ng/ml, coincided with an LPS dose-dependent increase in cell surface phosphatidylserine (PS), considered to promote coagulation. The increased PS expression was associated with an increased number of 7-AAD-positive cells indicating cell death. We conclude that enhancement of monocyte procoagulant activity in vitro by high concentrations of LPS may result from increased PS exposure due to apoptosis and necrosis. Therefore, the LPS concentrations used to examine monocyte procoagulant activity in vitro, should be carefully chosen.

Association Between HLA Haplotypes and Increased Serum Levels of IgG4 in Patients With Primary Sclerosing Cholangitis.

Increased serum levels of IgG4 have been reported in 9%-15% of patients with primary sclerosing cholangitis (PSC); it is not clear whether this increase contributes to pathogenesis. We performed genetic analyses of the HLA complex in patients with PSC from Norway, Sweden, and from the United States. We found an association between levels of IgG4 above the upper reference limit and specific HLA haplotypes. These patients had a significantly lower frequency of the strongest PSC risk factor, HLA-B*08, than patients without increased IgG4, and significantly higher frequencies of HLA-B*07 and HLA-DRB1*15. HLA genotype therefore might affect the serum concentration of IgG4, and increased IgG4 might be a marker of a distinct phenotype of PSC.

A Heparin-Coated Dialysis Filter (AN69 ST) Does Not Reduce Clotting during Hemodialysis when Compared to a Conventional Polysulfone Filter (F×8)

Background: We investigated whether the heparin-coated AN69 ST hemodialysis (HD) filter induced less hypercoagulability during HD than a conventional polysulfone filter (F×8). Methods: In a crossover design, 11 patients were treated alternately with AN69 ST and F×8 filters (45 sessions). All filters were primed with unfractionated heparin (UFH) and unadsorbed UFH was removed by saline flushing. Half the conventional dalteparin dose was given as a bolus dose at the start of HD. Clotting was evaluated hourly in the venous air trap. Prothrombin fragments 1 and 2 (PF1 + 2), antithrombin (AT), β-TG and anti-FXa activity were repeatedly measured. Results: One patient treated with enalapril had two repeated adverse reactions to the AN69 ST filter and was excluded from the study. Use of the AN69 ST filter did not decrease the mean clot score or PF1 + 2, but decreased β-TG compared to the F×8 filter. Conclusion: The heparin-coated AN69 ST filter did not induce less coagulation when compared to the F×8 filter.

Flow cytometry-sorted non-viable endotoxin-treated human monocytes are strongly procoagulant.

Monocytes/macrophages are important in disease states such as gram-negative sepsis and coronary artery disease. Following exposure to lipopolysaccharide (LPS), monocytes express tissue factor (TF), the main initiator of blood coagulation. We previously demonstrated that human monocytes treated with high concentrations of LPS, or with LPS and calcium ionophore, displayed higher TF activity than monocytes treated with only low concentrations of LPS, even though the monocytes under all conditions expressed similar amounts of cell surface TF antigen. Such restrainedTF activity is often referred to as encryption and its release as de-encryption. We also observed that the increase in TF activity, de-encryption, coincided with an increase in cell surface phosphatidylserine (PS) representing apoptosis and necrosis. In the present work, we separated LPS and LPS and calcium ionophore-treated human monocytes into two populations, one of mainly viable, PS negative cells, and one of mainly non-viable, PS positive cells, by sorting flow-cytometry. We observed that non-viable cells expressed considerably less TF antigen than viable cells. Despite this, non-viable cells were clearly more procoagulant than viable cells in two different coagulation assays. Procoagulant activity was dependent on both TF and PS. We consider the higher content of externalized PS in non-viable monocytes as the major reason for the stronger procoagulant activity of these cells. Thus, TF de-encryption appears largely to occur on PS positive, non-viable cells under these conditions. This supports the important role of PS in coagulation, and it suggests that PS expression signifying cell death, may be clinically relevant.

Hb Ullevaal [β78(EF2)Leu→Val; HBB: c.235C>G], a new hemoglobin variant interfering with Hb A1c measurement using a cation exchange high performance liquid chromatography method.

Abstract A new hemoglobin (Hb) variant was detected during Hb A1c measurement. DNA sequencing showed heterozygosity for the single nucleotide substitution (C > G) on the β-globin gene causing an amino acid change [β78(EF2)Leu→Val; HBB: c.235C > G]. The new Hb variant was designated Hb Ullevaal after the hospital at which it was discovered. Heterozygosity for Hb Ullevaal appears to have no clinical significance. However, it interferes with Hb A1c measurement by cation exchange high performance liquid chromatography (HPLC), causing falsely low Hb A1c concentration when using the Tosoh G7 apparatus in variant mode.

Elevated troponin I and NT-proBNP at the time of transplantation may predict a major adverse cardiac event in the early postoperative period after renal transplantation.

Kreiskrankenhaus Mindelheim Mindelheim, Germany 3 Department of Cardiac Surgery Ludwig Maximilians University Klinikum Grosshadern Munich, Germany 4 Munich Transplant Center Ludwig Maximilians University Klinikum Grosshadern Munich, Germany 5 Department of Clinical Radiology Ludwig Maximilians University Klinikum Grosshadern Munich, Germany 6 Institute of Pathology Ludwig Maximilians University Klinikum Grosshadern Munich, Germany 7 Munich Heart Alliance Munich, Germany

Anticoagulant effects of an antidiabetic drug on monocytes in vitro

INTRODUCTION Monocyte- and microparticle (MP)-associated tissue factor (TF) is upregulated in diabetes. Lipopolysaccharide (LPS) induces expression of TF and alternatively spliced TF (asTF) and increases MP release from monocytes. Using LPS-stimulated TF-bearing human monocytes, we examined whether glibenclamide, a sulfonylurea used to treat diabetes type 2, might possess anticoagulant properties. METHODS We studied the effects of glibenclamide on cell- and supernatant-associated procoagulant activity (Factor Xa-generating assay and clot formation assay), on expression of TF and asTF (flow cytometry, RT-qPCR, western blot) and on cell viability and MP release (flow cytometry). RESULTS Glibenclamide dose-dependently decreased procoagulant activity of cells and supernatants. The reduction in cellular procoagulant activity coincided with reduced expression of TF and asTF in cells, whereas cell viability remained almost unchanged. The glibenclamide-induced reduction in procoagulant activity of supernatants appeared to be associated with a decreased number of released MPs. CONCLUSIONS Reduction of monocyte- and supernatant-associated procoagulant activity by glibenclamide is associated with decreased expression of TF and asTF and possibly with a reduced MP number. Our data indicate that glibenclamide reduces the prothrombotic state in LPS-stimulated monocytes in vitro. Glibenclamide might therefore also have an anticoagulant effect in vivo, but this needs to be further evaluated.

HbA1c analysis by capillary electrophoresis – comparison with chromatography and an immunological method

Abstract Background: Haemoglobin A1c (HbA1c) has become an even more important analyte for clinical laboratories during recent years with the introduction of its diagnostic use for diabetes mellitus. Several different analytical principles can be used, each with their advantages and disadvantages. Aim: We wanted to compare Sebia Capillarys 2 Flex Piercing (Capillarys) with our routine HbA1c methods, which were an HPLC method (Tosoh G7) and an immunoassay (Tina-Quant on Roche Modular P) by analysing a large clinical material. Furthermore, we investigated sample stability. Methods: HbA1c analysis was performed in parallel by all three methods for more than 600 patient samples including common and some rare haemoglobin variants, as well as for several controls, some with set target values. Sample stability at room temperature and refrigerated was assessed for up to seven days. Results: Capillarys produced generally somewhat lower HbA1c values than both comparison methods, apparently due to positive bias for the comparison methods. Leaving out samples with haemoglobin variants, we found a mean bias (95% CI) for Capillarys compared to Tosoh G7 (without factorization) and Modular of −0.39 (−0.40 to −0.38) and −0.16 (−0.17 to −0.14) % HbA1c, respectively. HbA1c results were similar between instruments for samples from dialysis patients and for samples with heterozygous common haemoglobin variants, except that Tosoh G7 reported too low results in the presence of Hb E. For heterozygous Hb Raleigh, Capillarys and the immunoassay gave similar results. Conclusion: Capillarys is a convenient instrument for routine HbA1c analysis.

Six-day stability of erythrocyte and reticulocyte parameters in-vitro: A comparison of blood samples from healthy, iron-deficient, and thalassemic individuals

Abstract Introduction. Stability for up to 6 days’ storage of erythrocyte and reticulocyte parameters in samples from iron-deficient and thalassemic individuals has not yet been reported. This lack of knowledge challenges evaluation of the full blood count in referral samples for hemoglobinopathy evaluation. We therefore hereby present such sample stability data. Methods. We included fresh (less than 4 hours old) blood samples from eight healthy, eight iron-deficient, and 11 thalassemic individuals. A full blood count, including reticulocyte parameters, was performed on a Sysmex XE-2100 once daily during a 6-day storage period at room temperature. For healthy individuals, we also studied stability of refrigerated samples and investigated analytical and biological variation. Results. Hemoglobin concentration, erythrocyte count, and mean corpuscular hemoglobin were stable for 6 days in all diagnostic groups. Mean corpuscular volume increased less in samples from iron-deficient individuals while the number of reticulocytes increased more in samples from thalassemic, as compared to healthy individuals. Ret-He stability depended on its baseline value. Within-person biological variation in samples from healthy individuals was low both for erythrocyte parameters and for reticulocyte hemoglobin, while higher for reticulocyte counts. Conclusion. Results for hemoglobin concentration, erythrocyte count, and mean corpuscular hemoglobin are reliable in hemoglobinopathy investigation of referred samples for up to 6 days. Storage time-dependent changes of other erythrocyte and reticulocyte parameters in blood samples from iron-deficient and thalassemic individuals differ from those of healthy individuals.

Hb Oslo [β42(CD1)Phe→Ile; HBB: c.127T>A]: A Novel Unstable Hemoglobin Variant Found in a Norwegian Patient

Abstract Unstable hemoglobin (Hb) variants are the result of sequence variants in the globin genes causing precipitation of Hb molecules in red blood cells (RBCs). Intracellular inclusions derived from the unstable Hb reduce the life-span of the red cells and may cause hemolytic anemia. Here we describe a patient with a history of hemolytic anemia and low oxygen saturation. She was found to be carrier of a novel unstable Hb variant, Hb Oslo [β42(CD1)Phe→Ile (TTT>ATT), HBB: c.127T>A] located in the heme pocket of the β-globin chain. Three-dimensional modeling suggested that isoleucine at position 42 creates weaker interactions with distal histidine and with the heme itself, which may lead to altered stability and decreased oxygen affinity. At steady state, the patient was in good clinical condition with a Hb concentration of 8.0–9.0 g/dL. During virus infections, the Hb concentration fell and on six occasions during 4 years, the patient needed a blood transfusion.