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  • 1
    Language: English
    In: Journal of Chromatography A, June 13, 2014, Vol.1346, p.97(10)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.chroma.2014.04.048 Byline: C. John, K. Langer Abstract: acents Nanoparticle formation could be analysed by AF4 separation of dissolved and native albumin. acents AF4 with inline-coupled DLS shows the whole distribution of HSA particle diameter. acents Increase of hydrodynamic particle diameter while PEGylation could be shown. acents PEGylation degree could be determined. Author Affiliation: Institute of Pharmaceutical Technology and Biopharmacy, University of Muenster, Corrensstra[sz]e 48, Munster 48149, Germany Article History: Received 22 December 2013; Revised 14 April 2014; Accepted 15 April 2014
    Keywords: Albumin
    ISSN: 0021-9673
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Cognitive Therapy and Research, 2013, Vol.37(6), pp.1110-1120
    Description: Despite preliminary evidence that individuals with higher social anxiety tend to avoid eye contact during at least some social encounters, the function of this behavior remains unknown. Cognitive theories of social anxiety suggest that gaze avoidance may function as an attempt to avoid signs of social threat. However, it is unclear whether this behavior is effective for reducing anxiety and, if it is effective, whether this benefit is only present in the short-term. The goal of the current study was to test whether gaze avoidance is effective in reducing anxiety for individuals with higher social anxiety during short social conversations among peers. Participants completed a short social interaction with another undergraduate participant in which eye contact was manipulated halfway through the interaction. Recordings of the interactions were later coded for amount of eye contact; this allowed us to obtain an objective measure of adherence to the manipulation instructions. Participants were instructed to make either more or less eye contact, or continue as before. Being asked to make less eye contact was the most anxiety-provoking condition for participants with higher social anxiety. We propose, in line with previous research on safety behaviors, that avoiding eye contact in an effort to regulate state anxiety is an ineffective strategy over time for individuals with higher social anxiety. Therefore gaze avoidance may be a particularly important safety behavior to target in treatment for social anxiety disorder.
    Keywords: Social anxiety ; Gaze avoidance ; Eye contact ; Social interaction ; Safety behaviors
    ISSN: 0147-5916
    E-ISSN: 1573-2819
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  • 3
    Language: English
    In: Journal of Chromatography A, 13 June 2014, Vol.1346, pp.97-106
    Description: Nanoparticles used as drug delivery systems are of growing interest in the pharmaceutical field. Understanding the behaviour and effects of nanosystems in the human body is dependent on comprehensive characterisation of the systems especially with regard to size and size distribution. Asymmetrical flow field-flow fractionation (AF4) is a promising method for this challenge as this technique enables chromatographic separation of particles and solute molecules according to their respective size. Within this study AF4 was used for the characterisation of human serum albumin (HSA) based nanoparticles. In a first part, the most important aspects of method development like the choice of cross flow rate, focusing and the increase of sample concentration via outlet stream splitting on the sample separation were evaluated. Sample fractionation was controlled by inline-coupling of a dynamic light scattering detector (DLS, Zetasizer) and was confirmed by DLS batch mode measurements. In a second part the applicability of field-flow fractionation for characterisation of the HSA particle formation process by a desolvation method was evaluated. A time dependent particle formation was observed which was controlled by the amount of desolvating agent. Furthermore, field-flow fractionation in combination with in-line dynamic light scattering was used to monitor the increase of particle diameter during PEGylation of the resulting HSA nanoparticles. The separation of nanoparticles from dissolved polyethylene glycol (PEG) could successfully be used for determination of the particles’ PEGylation degree.
    Keywords: Asymmetrical Flow Field-Flow Fractionation (Af4) ; Dynamic Light Scattering (Dls) ; Nanoparticles ; Human Serum Albumin (HSA) ; Nanoparticle Pegylation ; Chemistry
    ISSN: 0021-9673
    E-ISSN: 18733778
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  • 4
    Language: English
    In: Applied Surface Science, August 30, 2015, Vol.347, p.378(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.apsusc.2015.04.071 Byline: S. Spek, M. Haeuser, M.M. Schaefer, K. Langer Abstract: Author Affiliation: (a) Institute of Pharmaceutical Technology and Biopharmacy, University of Muenster, Corrensstrasse 48, 48149 Muenster, Germany (b) nanoAnalytics, Heisenbergstrasse 11, 48149 Muenster, Germany Article History: Received 18 February 2015; Revised 7 April 2015; Accepted 9 April 2015
    Keywords: X-Ray Spectroscopy ; Nuclear Magnetic Resonance Spectroscopy
    ISSN: 0169-4332
    Source: Cengage Learning, Inc.
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  • 5
    Language: English
    In: International Journal of Pharmaceutics, 30 January 2014, Vol.461(1-2), pp.137-144
    Description: Nanoparticles composed of poly(DL-lactide-co-glycolide) (PLGA) represent promising colloidal drug carriers for improved drug targeting. Although most research activities are focused on intravenous application of these carriers the peroral administration is described to improve bioavailability of poorly soluble drugs. Based on these insights the manuscript describes a model tablet formulation for PLGA-nanoparticles and especially its analytical characterisation with regard to a nanosized drug carrier. Besides physico-chemical tablet characterisation according to pharmacopoeias the main goal of the study was the development of a suitable analytical method for the quantification of nanoparticle release from tablets. An analytical flow field-flow fractionation (AF4) method was established and validated which enables determination of nanoparticle content in solid dosage forms as well as quantification of particle release during dissolution testing. For particle detection a multi-angle light scattering (MALS) detector was coupled to the AF4-system. After dissolution testing, the presence of unaltered PLGA-nanoparticles was successfully proved by dynamic light scattering and scanning electron microscopy.
    Keywords: Plga-Nanoparticles ; Asymmetric Flow Field-Flow Fractionation (Af4) ; Multi-Angle Light Scattering (Mals) ; Dissolution Testing ; Drug Release ; Tablets ; Pharmacy, Therapeutics, & Pharmacology
    ISSN: 0378-5173
    E-ISSN: 1873-3476
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  • 6
    Language: English
    In: Transplantation Proceedings, 2011, Vol.43(4), pp.1303-1305
    Description: The occurrence of postoperative incisional hernia is more frequent after simultaneous pancreas–kidney transplantation compared with other transplanted parenchymal organs. These complications are especially dangerous in this patient population, because they can compromise the survival of the transplanted organ. We performed a retrospective review of a series of adult patients with incisional herniae after 23 consecutive simultaneous pancreas–kidney transplantations between January 2004 and June 2010 seeking to identify risk factors. All 23 patients had a body mass index (BMI) of 〈25. All surgeons used a similar technique, including a median incision with an intraperitoneal approach, and systemic venous and enteric drainage methods and a layered fascial closure. All combined pancreas–kidney transplant recipients received induction with thymoglobulin and maintenance therapy with sirolimus, reduced-dose cyclosporine and corticosteroids. An incisional hernia repair was performed in 8/23 patients (34.8%). Four reoperations were required in this group (50%), due to hemoperitoneum ( = 2), intra-abdominal abscess ( = 1), and venous thrombosis ( = 1). The mean elapsed time between transplantation and hernioplasty was 24.5 months (range, 8–51). There was no significant difference in age, gender, BMI, dialysis modality, or operative time among affected compared with the other members of the group. Despite lack of obesity we observed a relatively higher rate of postoperative herniase, possibly owing to the side effects of a thymoglobulin–sirolimus combination.
    Keywords: Biology ; Pharmacy, Therapeutics, & Pharmacology ; Anatomy & Physiology
    ISSN: 0041-1345
    E-ISSN: 1873-2623
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  • 7
    Language: English
    In: Transplantation Proceedings, December 2013, Vol.45(10), pp.3703-3704
    Description: The porphyrias are a group of disorders of the heme biosynthesis pathway that may present with acute life-threatening attacks, commonly exacerbated by a wide variety of medications. Many newer immunosuppressive medications, which are in use following kidney transplantation, have not been fully explored in acute porphyrias. A 53-year-old woman received a kidney from a deceased donor, after being on hemodialysis for 4 years. Hereditary coproporphyria was diagnosed at age 19 years. We administered tacrolimus, mycophenolate mofetil and steroid immunosuppression. In the immediate post-transplant periods she displayed abdominal pain and transient uroporphyrin elevation in parallel with slightly elevated (15 ng/mL) tacrolimus concentrations. As the target tacrolimus level was achieved, these findings disappeared. Tacrolimus, mycophenolate- mofetil, and steroid therapy for hereditery coproporphyri was safe, in the long term.
    Keywords: Biology ; Pharmacy, Therapeutics, & Pharmacology ; Anatomy & Physiology
    ISSN: 0041-1345
    E-ISSN: 1873-2623
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  • 8
    Language: English
    In: International Journal of Pharmaceutics, 30 January 2018, Vol.536(1), pp.211-221
    Description: Nanoparticles are promising drug delivery systems to overcome physiological barriers such as the blood-brain barrier. In this respect nanoparticle uptake into endothelial or epithelial cells is the first necessary step to overcome these obstacles. Therefore, a new strategy for the covalent attachment of drug targeting ligands on poly(lactic acid) (PLA) nanoparticles was developed and the influence of the resulting surface properties on the uptake behaviour in cerebral endothelial cells was investigated. PLA nanoparticles were modified on their surface by apolipoprotein E, penetratin, or ovalbumin using a newly developed vinyl sulfone-modified poly(vinyl alcohol)-derivative (VS-PVA) as steric stabilizer. With this approach an easy option for ligand coupling reactions to PVA-stabilized nanoparticles was achieved. All obtained formulations showed a favourable behaviour concerning cytotoxic effects on endothelial cells, not compromising their viability. Furthermore, a clear relation between cellular uptake and surface coupled functional ligand could be determined: Penetratin- and apolipoprotein E-modified nanoparticles showed a distinct higher cellular uptake than ovalbumin-modified or unmodified nanoparticles, which both can be explained by mechanistic reasons. Overall the use of the reactive VS-PVA as stabilizer for nanoparticle preparation is an universal and effective approach to couple several functional ligands to the particles’ surface for targeting applications.
    Keywords: Nanoparticles ; Surface Chemistry ; Poly(Lactic Acid) ; Drug Delivery ; Biocompatibility ; Apoe ; Penetratin ; Blood Brain Barrier ; Cell Culture ; Drug Targeting ; Pharmacy, Therapeutics, & Pharmacology
    ISSN: 0378-5173
    E-ISSN: 1873-3476
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  • 9
    Language: English
    In: Surface & Coatings Technology, 15 August 2018, Vol.347, pp.123-135
    Description: We have investigated the hardening response, residual stress generation and microstructural changes in aluminium alloy 2624 owing to laser shock peening. The alloy was studied in two heat treatment conditions, T351 and T39, that have 20% difference in yield strength: hence the effects of laser power density and multiple peen impacts on materials with nominally identical physical properties but with different hardening responses has been studied. Hardness was characterised by nanoindentation, and residual stresses were measured by incremental hole drilling. The magnitude and the depth of the peak compressive residual stresses increase with increasing power densities as well as the number of laser impacts, before reaching a saturation point above which loss of surface compression occurs. Maximum compressive residual stresses were around −350 MPa, and maximum hardness increase was around 22%. The treatment has a noticeable effect in changing the microstructures of the T351 temper while the T39 remained almost unchanged.
    Keywords: Engineering ; Chemistry
    ISSN: 0257-8972
    E-ISSN: 1879-3347
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  • 10
    Language: English
    In: Nanotechnology, 2015, Vol.26(14), p.145103 (12pp)
    Description: Modification with poly(ethylene glycol) (PEG) is a widely used method for the prolongation of plasma half-life of colloidal carrier systems such as nanoparticles prepared from human serum albumin (HSA). However, the quantification of the PEGylation extent is still challenging. Moreover, the influence of different PEG derivatives, which are commonly used for nanoparticle conjugation, has not been investigated so far. The objective of the present study is to develop a method for the quantification of PEG and to monitor the influence of diverse PEG reagents on the amount of PEG linked to the surface of HSA nanoparticles. A size exclusion chromatography method with refractive index detection was established which enabled the quantification of unreacted PEG in the supernatant. The achieved results were confirmed using a fluorescent PEG derivative, which was detected by photometry and fluorimetry. Additionally, PEGylated HSA nanoparticles were enzymatically digested and the linked amount of fluorescently active PEG was directly determined. All the analytical methods confirmed that under optimized PEGylation conditions a PEGylation efficiency of up to 0.5 mg PEG per mg nanoparticle could be achieved. Model calculations made a ‘brush’ conformation of the PEG chains on the particle surface very likely. By incubating the nanoparticles with fetal bovine serum the reduced adsorption of serum proteins on PEGylated HSA nanoparticles compared to non-PEGylated HSA nanoparticles was demonstrated using sodium dodecylsulfate polyacrylamide gel electrophoresis. Finally, the positive effect of PEGylation on plasma half-life was demonstrated in an in vivo study in mice. Compared to unmodified nanoparticles the PEGylation led to a four times larger plasma half-life.
    Keywords: Nanopartikel ; Serumalbumin ; Halbwertszeit ; Fluorimetrie ; Modellrechnung ; Ethylenglykol ; Brechungsindex ; Größenausschlusschromatographie ; Photometrie ; Protein ; Natriumdodecylsulfat ; Polyacrylamidgel ; Elektrophorese ; Serum ; In-Vivo-Untersuchung ; Engineering ; Physics;
    ISSN: 0957-4484
    E-ISSN: 1361-6528
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