Zum Einfluss der oberflächennahen elektrischen Feldverteilung an nanostrukturierten Biomaterialoberflächen auf das Biosystem

Nanostrukturierte Oberflächen wirken auf die Proteinadsorption. Lokal variierende elektrische Feldstärken nahe Nanotopografien werden als Ursache für die Modulation der Adsorption diskutiert. Bisher wurde dabei von rein metallischen Oberflächen ausgegangen. In dieser Arbeit wurde am Beispiel einer topografischen Nanostruktur aus Titan der Einfluss der TiO2-Passivschicht auf die elektrische Feldverteilung mittels FEM-Berechnungen untersucht. Weiter wurde die isolierte Wirkung des elektrischen Feldes auf das Biosystem an einer elektronischen Nanostruktur aus Silizium experimentell untersucht

Simulation of the Electric Field Distribution Near a Topographically Nanostructured Titanium-Electrolyte Interface: Influence of the Passivation Layer

A major challenge in biomaterials research is the regulation of protein adsorption at metallic implant surfaces. Recently, a number of studies have shown that protein adsorption can be influenced by metallic nanotopographies, which are discussed to increase electric field strengths near sharp edges and spikes. Since many metallic biomaterials form a native passivation layer with semiconducting properties, we have analyzed the influence of this layer on the near-surface electric field distribution of a nanostructure using finite element simulations. The Poisson-Boltzmann equation was solved for a titanium nanostructure covered by a TiO2 passivation layer in contact with a physiological NaCl solution (bulk concentration 0.137 mol/L). In contrast to a purely metallic nanostructure, the electric field strengths near sharp edges and spikes can be lower than in planar regions if a passivation layer is considered. Our results demonstrate that the passivation layer has a significant influence on the near-surface electric field distribution and must be considered for theoretical treatments of protein adsorption on passivated metals like titanium

Extracorporeal hemoperfusion as a potential therapeutic option for critical accumulation of rivaroxaban

Because of its efficacy, ease of dosing, and safety, the direct oral anticoagulant rivaroxaban is increasingly applied in a number of indications, for example, prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation and treatment of deep vein thrombosis and pulmonary embolism. Median therapeutic peak plasma concentrations range from 46 to 270 µg/L, depending on the respective indication. However, there are concerns regarding the accumulation of the drug in patients with impaired renal clearance or in case of overdosing, potentially leading to an increased risk of bleeding. With its high degree of protein binding of 92–95%, rivaroxaban is regarded as non-dialyzable, as also suggested by results from a clinical study conducted by Dias et al.. Since protein binding is regarded as not a limiting factor in hemoperfusion, the removal of rivaroxaban, as for example by commonly available coated charcoal cartridges, has been deemed possible, but experimental evidence is still lacking. While Andexanet alfa may offer a promising approach to reverse the FXa inhibitor-mediated anticoagulation of rivaroxaban, it has not yet been approved. In case of rivaroxaban-related major bleeding events or emergency interventions with a high bleeding risk, therefore, a fast and effective countermeasure is urgently needed. Here, we present experimental work to remove rivaroxaban from the blood by means of hemoperfusion using an approved adsorption device (CytoSorb®; Cyto¬Sorbents Europe, Germany). Currently, CytoSorb is used mainly in patients with severe infections and sepsis (cytokine storm). We applied a model device containing 60 mL of the adsorbent polyvinylpyrrolidone-coated polystyrene-divinylbenzene copolymer in an in vitro recirculation system to remove high plasma concentrations of rivaroxaban (571 ± 20 µg/L) from citrate-anticoagulated human whole blood (1,000 mL, flow rate 40 mL/min) during 120 min of hemoperfusion (Fig. 1a). Molecules are captured on the internal pore surface of polystyrene-divinylbenzene by nonspecific hydrophobic interactions, whereby solutes with molecular weights equal to and larger than that of albumin, particularly clotting factors, are excluded from adsorption by adjustment of the pore size distribution

The Utility of Miniaturized Adsorbers in Exploring the Cellular and Molecular Effects of Blood Purification: A Pilot Study with a Focus on Immunoadsorption in Multiple Sclerosis

Immunoadsorption (IA) has proven to be clinically effective in the treatment of steroid-refractory multiple sclerosis (MS) relapses, but its mechanism of action remains unclear. We used miniaturized adsorber devices with a tryptophan-immobilized polyvinyl alcohol (PVA) gel sorbent to mimic the IA treatment of patients with MS in vitro. The plasma was screened before and after adsorption with regard to disease-specific mediators, and the effect of the IA treatment on the migration of neutrophils and the integrity of the endothelial cell barrier was tested in cell-based models. The in vitro IA treatment with miniaturized adsorbers resulted in reduced plasma levels of cytokines and chemokines. We also found a reduced migration of neutrophils towards patient plasma treated with the adsorbers. Furthermore, the IA-treated plasma had a positive effect on the endothelial cell barrier’s integrity in the cell culture model. Our findings suggest that IA results in a reduced infiltration of cells into the central nervous system by reducing leukocyte transmigration and preventing blood–brain barrier breakdown. This novel approach of performing in vitro blood purification therapies on actual patient samples with miniaturized adsorbers and testing their effects in cell-based assays that investigate specific hypotheses of the pathophysiology provides a promising platform for elucidating the mechanisms of action of those therapies in various diseases

Increasing the Yield in Targeted Next-Generation Sequencing by Implicating CNV Analysis, Non-Coding Exons and the Overall Variant Load: The Example of Retinal Dystrophies

<div><p>Retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA) are major causes of blindness. They result from mutations in many genes which has long hampered comprehensive genetic analysis. Recently, targeted next-generation sequencing (NGS) has proven useful to overcome this limitation. To uncover “hidden mutations” such as copy number variations (CNVs) and mutations in non-coding regions, we extended the use of NGS data by quantitative readout for the exons of 55 RP and LCA genes in 126 patients, and by including non-coding 5′ exons. We detected several causative CNVs which were key to the diagnosis in hitherto unsolved constellations, e.g. hemizygous point mutations in consanguineous families, and CNVs complemented apparently monoallelic recessive alleles. Mutations of non-coding exon 1 of <i>EYS</i> revealed its contribution to disease. In view of the high carrier frequency for retinal disease gene mutations in the general population, we considered the overall variant load in each patient to assess if a mutation was causative or reflected accidental carriership in patients with mutations in several genes or with single recessive alleles. For example, truncating mutations in <i>RP1</i>, a gene implicated in both recessive and dominant RP, were causative in biallelic constellations, unrelated to disease when heterozygous on a biallelic mutation background of another gene, or even non-pathogenic if close to the C-terminus. Patients with mutations in several loci were common, but without evidence for di- or oligogenic inheritance. Although the number of targeted genes was low compared to previous studies, the mutation detection rate was highest (70%) which likely results from completeness and depth of coverage, and quantitative data analysis. CNV analysis should routinely be applied in targeted NGS, and mutations in non-coding exons give reason to systematically include 5′-UTRs in disease gene or exome panels. Consideration of all variants is indispensable because even truncating mutations may be misleading.</p></div

Mutational spectrum in RP and LCA patients.

<p>Percentages refer to patients with mutations in the respective gene that are considered causative. The distribution of causative mutations across many genes, each contributing a relatively small fraction to the mutational spectrum, confirms the extensive genetic heterogeneity of retinal dystrophies. Note that the three patients that were found to carry X-linked mutations are not contained in the schemes A – B. <b>A.</b> arRP. <b>B.</b> adRP. Note that the percentages refer to a relatively small adRP cohort in this study. <b>C.</b> LCA. <b>D.</b> Functional categorization of genes that were found to carry causative mutations in our study. Mutations in genes encoding components of the photoreceptor’s connecting cilium and associated structures were predominant.</p

Comparison of this study with previous NGS studies on retinal dystrophies.

*<p>Positive controls not included.</p>**<p>Additional samples from the same families not included. Gene numbers in brackets include additionally screened candidate genes that are not yet proven retinal disease genes. BBS, Bardet-Biedl syndrome; CRD, cone-rod dystrophy; CD, cone dystrophy; CSNB, congenital stationary night blindness; FA, fundus albipunctatus; STGD, Morbus Stargardt; USH, Usher syndrome.</p

Causative mutations and putatively pathogenic variants identified in this study.

<p>Causative alleles are being listed as “allele 1” and “allele 2” in resolved cases. Additional alleles are shown if the minor allele frequency is below 3% and if <i>in silico</i> prediction suggests putative pathogenicity. The inheritance pattern was largely delineated from pedigree informations. In patients 22, 23, 77, 100, 116 and 119, the true mode of inheritance had not been evident from the pedigree information and was finally deduced from the genotype. a, this study. References for studies cited in this table can be found in the Supplementary Material (References S1 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078496#pone.0078496.s001" target="_blank">File S1</a>). n.d., not defined; f, female; m, male; ar, autosomal recessive; ad, autosomal dominant; s, sporadic. Xl, X-linked. Cau, Caucasian; Ger, Germany; Tur, Turkey; KSA, Kingdom of Saudi Arabia; Pol, Poland; Au, Austria; Syr, Syria; Pak, Pakistan; DRC, Democratic Republic of the Congo; Mor, Morocco; UAE, United Arab Emirates; E-Eur, East Europe; SE-Eur, Southeast Europe.</p