The CentriMag Centrifugal Blood Pump as a Benchmark for In Vitro Testing of Hemocompatibility in Implantable Ventricular Assist Devices

Implantable ventricular assist devices (VADs) have proven efficient in advanced heart failure patients as a bridge‐to‐transplant or destination therapy. However, VAD usage often leads to infection, bleeding, and thrombosis, side effects attributable to the damage to blood cells and plasma proteins. Measuring hemolysis alone does not provide sufficient information to understand total blood damage, and research exploring the impact of currently available pumps on a wider range of blood cell types and plasma proteins such as von Willebrand factor (vWF) is required to further our understanding of safer pump design. The extracorporeal CentriMag (Thoratec Corporation, Pleasanton, CA, USA) has a hemolysis profile within published standards of normalized index of hemolysis levels of less than 0.01 g/100 L at 100 mm Hg but the effect on leukocytes, vWF multimers, and platelets is unknown. Here, the CentriMag was tested using bovine blood (n = 15) under constant hemodynamic conditions in comparison with a static control for total blood cell counts, hemolysis, leukocyte death, vWF multimers, microparticles, platelet activation, and apoptosis. The CentriMag decreased the levels of healthy leukocytes (P < 0.006), induced leukocyte microparticles (P < 10^?5), and the level of high molecular weight of vWF multimers was significantly reduced in the CentriMag (P < 10^?5) all compared with the static treatment after 6 h in vitro testing. Despite the leukocyte damage, microparticle formation, and cleavage of vWF multimers, these results show that the CentriMag is a hemocompatible pump which could be used as a standard in blood damage assays to inform the design of new implantable blood pumps.     

Quantitative improvement in signal-averaged electrocardiography after coronary artery bypass grafting.

Abnormal signal-averaged electrocardiography (SAECG) reflects slow and heterogeneous myocardial conduction, predicting ventricular arrhythmia and sudden cardiac death in patients with ischemic heart disease. The purpose of this study was to investigate the quantitative effect of coronary artery bypass grafting (CABG) on SAECG, which is still controversial, and to identify the factors that are related to it. Pre- and postoperative SAECGs were recorded in 100 patients who underwent CABG. Compared parameters included filtered QRS duration (dQRS), root mean square voltage in the terminal 40 ms of the QRS complex (RMS40), and duration of the terminal low-amplitude signal less than 40 microV (LAS40). All 3 parameters in SAECG improved significantly after CABG (dQRS: 105+/-21 ms-->99+/-18 ms, RMS40: 55+/-45 microV-->65+/-41 microV, LAS40: 29+/-19 ms-->25+/-12 ms). The improvements in SAECG were greater in patients who underwent complete revascularization and in those without prior myocardial infarction. In conclusion, CABG improved SAECG quantitatively, even in patients with normal SAECG. However, this improving effect was variable and closely related to the presence of prior myocardial infarction and the completeness of revascularization.     

Structural Variations of the Cell Wall Precursor Lipid II and Their Influence on Binding and Activity of the Lipoglycopeptide Antibiotic Oritavancin

Oritavancin is a semisynthetic derivative of the glycopeptide antibiotic chloroeremomycin with activity against Gram-positive pathogens, including vancomycin-resistant staphylococci and enterococci. Compared to vancomycin, oritavancin is characterized by the presence of two additional residues, a hydrophobic 4′-chlorobiphenyl methyl moiety and a 4-epi-vancosamine substituent, which is also present in chloroeremomycin. Here, we show that oritavancin and its des-N-methylleucyl variant (des-oritavancin) effectively inhibit lipid I- and lipid II-consuming peptidoglycan biosynthesis reactions in vitro. In contrast to that for vancomycin, the binding affinity of oritavancin to the cell wall precursor lipid II appears to involve, in addition to the d-Ala-d-Ala terminus, other species-specific binding sites of the lipid II molecule, i.e., the crossbridge and d-isoglutamine in position 2 of the lipid II stem peptide, both characteristic for a number of Gram-positive pathogens, including staphylococci and enterococci. Using purified lipid II and modified lipid II variants, we studied the impact of these modifications on the binding of oritavancin and compared it to those of vancomycin, chloroeremomycin, and des-oritavancin. Analysis of the binding parameters revealed that additional intramolecular interactions of oritavancin with the peptidoglycan precursor appear to compensate for the loss of a crucial hydrogen bond in vancomycin-resistant strains, resulting in enhanced binding affinity. Augmenting previous findings, we show that amidation of the lipid II stem peptide predominantly accounts for the increased binding of oritavancin to the modified intermediates ending in d-Ala-d-Lac. Corroborating our conclusions, we further provide biochemical evidence for the phenomenon of the antagonistic effects of mecA and vanA resistance determinants in Staphylococcus aureus, thus partially explaining the low frequency of methicillin-resistant S. aureus (MRSA) acquiring high-level vancomycin resistance.     

Behçet's disease in patients of German and Turkish origin living in Germany: a comparative analysis

OBJECTIVE: To evaluate the relationship between ethnic origin and manifestations of Beh?et's disease (BD) in patients of German and Turkish origin living in Germany. METHODS: Between 1995 and 2000, 32 patients of German and 33 patients of Turkish origin living in Germany were evaluated for the entire spectrum of disease manifestations, disease severity, HLA associations, sex, age at disease manifestation, and time to diagnosis. RESULTS: There were no statistically significant differences between German and Turkish patients. There was no association of sex or HLA-B51 with any manifestation of BD. The only significant difference between the 2 groups was the median time from the first manifestation of the disease to diagnosis, which was 0 years for the Turkish, but 3.5 years for the German patients (p = 0.0005). Additionally, 4 patients of German origin had been misdiagnosed as having spondyloarthropathy (SpA) before the final diagnosis of BD was made (12%). In comparison to Turkish patients living in Turkey (data from the literature), only 2 differences were found: one concerned the frequency of ocular involvement (lower in the patients in Turkey), and the other the male to female ratio, which was reported as 1.03:1 in Turkey, but 3.7:1 in Germany. CONCLUSION: Our results do not favor an ethnic influence on the expression of BD. Environmental influences may be responsible for the higher frequency of ocular manifestations and the higher male to female ratio in patients living in Germany compared to those living in Turkey.     

Protective anti-V antibodies inhibit Pseudomonas and Yersinia translocon assembly within host membranes

Pathogenic Yersinia species and Pseudomonas aeruginosa share a similar type III secretion/translocation system. The translocation system consists of 3 secreted proteins, YopB/PopB, YopD/PopD, and LcrV/PcrV; the latter is known to be a protective antigen. In an in vitro assay, the translocation system causes the lysis of erythrocytes infected with wild-type (wt) P. aeruginosa. wt Y. enterocolitica is not hemolytic, but a multiknockout mutant deprived of all the effectors and of YopN ( Delta HOPEMN) is hemolytic. In the presence of antibodies against PcrV and Y. pestis LcrV, the hemolytic activity of P. aeruginosa was inhibited. Similarly, the hemolytic activity of Delta HOPEMN was inhibited in the presence of anti-LcrV antibodies. The assembly of the translocon, composed of PopB/D and YopB/D proteins, was disturbed in immunoprotected erythrocyte membranes, mimicking the phenotypes of V knockout mutants. Thus, protective antibodies against the V antigens of Yersinia species and P. aeruginosa act at the level of the formation of the translocon pore in membranes of infected host cells by blocking the function of LcrV/PcrV. The hemolysis assay could be adapted for high-throughput screening of anti-infectious compounds that specifically target the type III translocon.