Urethane polythioether self-crosslinking resins

A straightforward methodology for the synthesis of polythioether resins and resulting coatings was elaborated. The resins were produced via radical stepwise polyaddition of functional bisalkene and bisthiol monomers to yield self-crosslinkable polythioethers, which can be formulated as one-component systems. The thermal curing of these self-crosslinking resins is enabled by the presence of both hydroxyl and blocked isocyanate moieties, thereby resulting in the formation of a urethane polythioether network. Furthermore, the presence of the thioether functions offered the opportunity to alter thermal and mechanical properties by oxidation into sulfoxide or sulfone linkages, resulting in polysulfoxide and -sulfone containing coatings. Thiol-ene chemistry in combination with blocked isocyanate chemistry provides a new platform for functional urethane- and sulfide-containing coatings, which can be tailored to a wide variety of applications

A novel Malonamide Periodic Mesoporous Organosilica (PMO) for controlled Ibuprofen release

Controlled drug release gained a sharply increasing interest over recent years. Multiple materials have been screened as possible drug carriers, ranging from biodegradable polymers to hydroxyapatite[1]. Periodic Mesoporous Organosilicas are valuable alternatives as they possess a high chemical and thermal stability combined with a biocompatible nature[2]. Furthermore, their large internal surface area permits a high drug loading. Careful selection of the organic ‘bridged’ functionality allows a controlled release with respect to external stimuli, such as pH or temperature, of the drugs which are adsorbed via weak and reversible interactions, e.g. H-bonding, ionic and hydrophobic-phobic interaction[3]. In this contribution a novel malonamide (MA-PMO) and a methyl-malonamide PMO (mMA-PMO) bearing a high amount of functionalities, capable of multiple intramolecular interactions, are developed and thoroughly characterized[4]. Subsequently, these hybrid materials are evaluated in the controlled drug release of Ibuprofen

A novel malonamide Periodic Mesoporous Organosilica (PMO) for controlled ibuprofen release

Controlled drug release gained a sharply increasing interest over recent years. Multiple materials have been screened as possible drug carriers, ranging from biodegradable polymers to hydroxyapatite[1]. Periodic Mesoporous Organosilicas are valuable alternatives as they possess a high chemical and thermal stability combined with a biocompatible nature[2]. Furthermore, their large internal surface area permits a high drug loading. Careful selection of the organic ‘bridged’ functionality allows a controlled release with respect to external stimuli, such as pH or temperature, of the drugs which are adsorbed via weak and reversible interactions, e.g. H-bonding and hydrophobic-phobic interaction[3]. In this contribution a novel malonamide (MA-PMO) and a methyl-malonamide PMO (mMA-PMO) bearing a high amount of H-bond donors and acceptors is developed and thoroughly characterised. Subsequently, these hybrid materials are evaluated in the controlled drug release of Ibuprofen

A Novel Malonamide Periodic Mesoporous Organosilica (PMO) for tuneable ibuprofen release

Incorporation of organic functionalities within porous materials is a very elegant manner to control the administration of therapeutic drugs. Delayed drug-release profile originates from weak and reversible interactions (e.g., electrostatic, hydrophobic–hydrophobic and H-bonding interaction) between the modified carrier and the drug molecule. Two new silsesquioxane PMO precursors were synthesized in a quick and facile Schotten-Baumann reaction of (3-aminopropyltriethoxy)silane and (N-methyl-3-aminopropyltrimethoxy)-silane with malonylchloride, respectively. Based on these bis(3-(triethoxysilyl)propyl)malonamide (MA) and N,N-dimethyl-N,N-bis(3-(triethoxysilyl)propyl)malonamide (mMA) precursors, an extensive range of 2D hexagonal PMOs with high functional loading was obtained by the co-condensation with tetraethyl orthosilicate (TEOS) in a typical PMO synthesis (acidic medium, P123, KCl). The materials showed good ordering up to 20 mol% of functional loading, a large surface area (up to 550 m2/g) and wide pores (∼7 nm). The malonamide-type PMOs are capable to adsorb large amounts of ibuprofen (130 mg/g) as a hydrophobic model drug. Release experiments are performed in a phosphate buffer solution at pH 7.4 and show a controlled desorption of Ibuprofen over 24 hours; a largely expanded times pan compared to mesoporous silicas. Moreover, we are able to tune the release profile by varying the content of organic bridges in the PMO pores

Anthracene-based thiol-ene networks with thermo-degradable and photo-reversible properties

Reversible networks based on an alkenefunctionalized dimer of 9-anthracenemethanol were synthesized by photoinitiated radical thiol ene polyaddition, using either a poly(dimethylsiloxane-co-propylmercaptomethylsiloxane) or a novel aliphatic trithiol synthesized from 1,2,4trivinylcyclohexane in a simple two-step procedure. The obtained networks were analyzed using differential scanning calorimetry, dynamic mechanical analysis, polarization microscopy, X-ray diffraction, and (photo)rheology. The two types of networks showed weak endothermic transitions between 50 and 60 degrees C, which proved to originate either from melting of a crystalline anthracene-dimer phase (trithiol network) or from a liquid crystalline phase (PDMS network) based on X-ray diffraction and polarization microscopy. Using rheology, both types of networks were shown to cleanly decompose into multifunctional anthracene monomers at temperatures above 180 degrees C. Irradiation of these anthracene monomers resulted in the formation of networks having similar physical properties as the original materials

Selected liver grafts from donation after circulatory death can be safely used for retransplantation – a multicenter retrospective study

Due to the growing number of liver transplantations (LTs), there is an increasing number of patients requiring retransplantation (reLT). Data on the use of grafts from extended criteria donors (ECD), especially donation after circulatory death (DCD), for reLT are lacking. We aimed to assess the outcome of patients undergoing reLT using a DCD graft in the Netherlands between 2001 and July 2018. Propensity score matching was used to match each DCD-reLT with three DBD-reLT cases. Primary outcomes were patient and graft survival. Secondary outcome was the incidence of biliary complications, especially nonanastomotic strictures (NAS). 21 DCD-reLT were compared with 63 matched DBD-reLTs. Donors in the DCD-reLT group had a significantly lower BMI (22.4 vs. 24.7 kg/m2, P-value = 0.02). Comparison of recipient demographics and ischemia times yielded no significant differences. Patient and graft survival rates were comparable between the two groups. However, the occurrence of nonanastomotic strictures after DCD-reLT was significantly higher (38.1% vs. 12.7%, P-value = 0.02). ReLT with DCD grafts does not result in inferior patient and graft survival compared with DBD grafts in selected patients. Therefore, DCD liver grafts should not routinely be declined for patients awaiting reLT

The Relation Between Histological, Tumor-Biological and Clinical Parameters in Deep and Superficial Leiomyosarcoma and Leiomyoma

Purpose: Leiomyosarcomas (LMS) of deep and superficial tissues were examined to identify prognostic markers explaining their different biological behaviour and to define differences between cutaneous and subcutaneous LMS. LMS and leiomyomas (LM) of the skin were compared to and consistent differences that could aid in the (sometimes difficult) diagnosis

Pretransplant sequential hypo- and normothermic machine perfusion of suboptimal livers donated after circulatory death using a hemoglobin-based oxygen carrier perfusion solution

Ex situ dual hypothermic oxygenated machine perfusion (DHOPE) and normothermic machine perfusion (NMP) of donor livers may have a complementary effect when applied sequentially. While DHOPE resuscitates the mitochondria and increases hepatic adenosine triphosphate (ATP) content, NMP enables hepatobiliary viability assessment prior to transplantation. In contrast to DHOPE, NMP requires a perfusion solution with an oxygen carrier, for which red blood cells (RBC) have been used in most series. RBC, however, have limitations and cannot be used cold. We, therefore, established a protocol of sequential DHOPE, controlled oxygenated rewarming (COR), and NMP using a new hemoglobin-based oxygen carrier (HBOC)-based perfusion fluid (DHOPE-COR-NMP trial, NTR5972). Seven livers from donation after circulatory death (DCD) donors, which were initially declined for transplantation nationwide, underwent DHOPE-COR-NMP. Livers were considered transplantable if perfusate pH and lactate normalized, bile production was >= 10 mL and biliary pH > 7.45 within 150 minutes of NMP. Based on these criteria five livers were transplanted. The primary endpoint, 3-month graft survival, was a 100%. In conclusion, sequential DHOPE-COR-NMP using an HBOC-based perfusion fluid offers a novel method of liver machine perfusion for combined resuscitation and viability testing of suboptimal livers prior to transplantation