Stabilized biocompatible and bioabsorbable trigyceride-based coatings for coronary stents

Cardiovascular diseases (e.g arthrosclerosis) are the primary cause of death in our Western Society. A possible treatment for arthrosclerosis is the implantation of a drug eluting stent (DES). Its advantage in comparison with bare stents is that the addition of drugs can prevent restenosis. The goal of this research project is to develop a coating that is biocompatible, bioabsorbable, plastically deformable and has a controllable drug release. The developed coatings are based on 3 or more triacylglycerols, which undergo an interesterification reaction to interexchange the acyl residues. The interesterification reaction is executed by weighing the triaglycerols, followed by drying them overnight in a vacuum oven at 100°C. Next, sodiummethoxide is added. The reaction completes within 1 hour under a nitrogen flow. To stop the reaction, 2 ml of a 20 wt% citric acid solution is added and the reaction compartment is cooled down. Afterwards the mixture is washed several times and dried at 100°C. The last step is to filter the mixture through a membrane filter in a vacuum oven at 100°C. To control the distribution of the randomized triacylglycerols, the coatings are analyzed with HPLC RI. The coatings are further characterized by their slip melting point (SMP) After interesterification, the coating material is checked for mechanical and drug release properties. Therefore, the coating is applied on stent samples with a home built spraying device. For each coating composition, the spraying parameters are optimized to obtain an equal coating distribution on the stent material. Mechanical properties are investigated by performing integrity tests and stent crimping and expansion tests. Coating integrity is checked with a simulated stenosis test at 37°C, in which the applied pressure can be changed. For a low pressure, the loss of coating material is about 5 %, while for a high pressure, the loss of coating rises up to 10 - 15%. Also, scratch tests with the Falex MUST tester are performed, which showed a good coating resistance against scratches. Stent crimping is performed manually. Before and after stent crimping and stent expansion, stents are visually checked with a light microscope for defects such as cracks or delaminations. In order to test the performance of the coatings, the in vitro release of paclitaxel and rapamycine from coated stents was tested. The in vitro drug release is performed at 37°C and is analyzed with HPLC UV-VIS. After an initial burst during the first 2 – 4 hours, the drug release is constant and mediated by diffusion. After 24 h, less then 10% is released, followed by a period of constant release for several weeks to months, depending on the coating composition. Triglyceride based coatings are promising to control drug release from stents during several weeks.status: accepte

DNA diagnostics of hereditary hearing loss : a targeted resequencing approach combined with a mutation classification system

Although there are nearly 100 different causative genes identified for nonsyndromic hearing loss (NSHL), Sanger sequencing-based DNA diagnostics usually only analyses three, namely, GJB2, SLC26A4, and OTOF. As this is seen as inadequate, there is a need for high-throughput diagnostic methods to detect disease-causing variations, including single-nucleotide variations (SNVs), insertions/deletions (Indels), and copy-number variations (CNVs). In this study, a targeted resequencing panel for hearing loss was developed including 79 genes for NSHL and selected forms of syndromic hearing loss. One-hundred thirty one presumed autosomal-recessive NSHL (arNSHL) patients of Western-European ethnicity were analyzed for SNVs, Indels, and CNVs. In addition, we established a straightforward variant classification system to deal with the large number of variants encountered. We estimate that combining prescreening of GJB2 with our panel leads to a diagnosis in 25%-30% of patients. Our data show that after GJB2, the most commonly mutated genes in a Western-European population are TMC1, MYO15A, and MYO7A (3.1%). CNV analysis resulted in the identification of causative variants in two patients in OTOA and STRC. One of the major challenges for diagnostic gene panels is assigning pathogenicity for variants. A collaborative database collecting all identified variants from multiple centers could be a valuable resource for hearing loss diagnostics