Biomedical subjects

Ulrich Pison

Publications and source records attributed to Ulrich Pison.

6 recordsLinked to original sources

PubMed2006

Maghemite nanoparticles protectively coated with poly(ethylene imine) and poly(ethylene oxide)-block-poly(glutamic acid).

Superparamagnetic iron oxide particles (SPIO) of maghemite were prepared in aqueous solution and subsequently stabilized with polymers in two layer-by-layer deposition steps. The first layer around the maghemite core is formed by poly(ethylene imine) (PEI), and the second one is formed by poly(ethylene oxide)-block-poly(glutamic acid) (PEO-PGA). The hydrodynamic diameter of the particles increases stepwise from D(h) = 25 nm (parent) via 35 nm (PEI) to 46 nm (PEI plus PEO-PGA) due to stabilization. This is accompanied by a switching of their zeta-potentials from moderately positive (+28 mV) to highly positive (+50 mV) and finally slightly negative (-3 mV). By contrast, the polydispersity indexes of the particles remain constant (ca. 0.15). Mössbauer spectroscopy revealed that the iron oxide, which forms the core of the particles, is only present as Fe(III) in the form of superparamagnetic maghemite nanocrystals. The magnetic domains and the maghemite crystallites were found to be identical with a size of 12.0 +/- 0.5 nm. The coated maghemite nanoparticles were tested to be stable in water and in physiological salt solution for longer than 6 months. In contrast to novel methods for magnetic nanoparticle production, where organic solvents are necessary, the procedure proposed here can dispense with organic solvents. Magnetic resonance imaging (MRI) experiments on living rats indicate that the nanoparticles are useful as an MRI contrast agent.

Animals↗

PubMed2006

Nanomedicine for respiratory diseases.

Nanotechnology provides new materials in the nanometer range with many potential applications in clinical medicine and research. Due to their unique size-dependent properties nanomaterial such as nanoparticles offer the possibility to develop both new therapeutic and diagnostic tools. Thus, applied nanotechnology to medical problems--nanomedicine--can offer new concepts that are reviewed. The ability to incorporate drugs into nanosystems displays a new paradigm in pharmacotherapy that could be used for cell-targeted drug delivery. Nontargeted nanosystems such as nanocarriers that are coated with polymers or albumin and solid lipid particles have been used as transporter in vivo. However, nowadays drugs can be coupled to nanocarriers that are specific for cells and/or organs. Thus, drugs that are either trapped within the carriers or deposited in subsurface oil layers could be specifically delivered to organs, tumors and cells. These strategies can be used to concentrate drugs in selected target tissues thus minimizing systemic side effects and toxicity. In addition to these therapeutic options, nanoparticle-based "molecular" imaging displays a field in which this new technology has set the stage for an evolutionary leap in diagnostic imaging. Based on the recent progress in nanobiotechnology there is potential for nanoparticles and -systems to become useful tools as therapeutic and diagnostic tools in the near future.

Animals↗

PubMed2006

One-pot synthesis of pegylated ultrasmall iron-oxide nanoparticles and their in vivo evaluation as magnetic resonance imaging contrast agents.

A well-defined copolymer poly(oligo(ethylene glycol) methacrylate-co-methacrylic acid) P(OEGMA-co-MAA) was studied as a novel water-soluble biocompatible coating for superparamagnetic iron oxide nanoparticles. This copolymer was prepared via a two-step procedure: a well-defined precursor poly(oligo(ethylene glycol) methacrylate-co-tert-butyl methacrylate), P(OEGMA-co-tBMA) (M(n) = 17300 g mol(-1); M(w)/M(n) = 1.22), was first synthesized by atom-transfer radical polymerization in the presence of the catalyst system copper(I) chloride/2,2'-bipyridyl and subsequently selectively hydrolyzed in acidic conditions. The resulting P(OEGMA-co-MAA) was directly utilized as a polymeric stabilizer in the nanoparticle synthesis. Four batches of ultrasmall PEGylated magnetite nanoparticles (i.e., with an average diameter below 30 nm) were prepared via aqueous coprecipitation of iron salts in the presence of variable amounts of P(OEGMA-co-MAA). The diameter of the nanoparticles could be easily tuned in the range 10-25 nm by varying the initial copolymer concentration. Moreover, the formed PEGylated ferrofluids exhibited a long-term colloidal stability in physiological buffer and could therefore be studied in vivo by magnetic resonance (MR) imaging. Intravenous injection into rats showed no detectable signal in the liver within the first 2 h. Maximum liver accumulation was found after 6 h, suggesting a prolongated circulation of the nanoparticles in the bloodstream as compared to conventional MR imaging contrast agents.

Animals↗

PubMed2006

Nanoparticle-based diagnosis and therapy.

Nanoparticles are at the leading edge of the rapidly developing field of material science in nanotechnology with many potential applications in clinical medicine and research. Due to their unique size-dependent properties nanoparticles offer the possibility to develop both new therapeutic and diagnostic tools. The ability to incorporate drugs into nanosystems displays a new paradigm in pharmacotherapy that could be used for cell-targeted drug delivery. Nontargeted nanosystems such as nanocarriers that are coated with polymers or albumin and solid lipid particles have been used to transport a large number of compounds. However, nowadays drugs can be coupled to nanocarriers that are specific for cells and/or organs. Thus, drugs that are either trapped within the carriers or deposited in subsurface oil layers could be specifically delivered to organs, tumors and cells. These strategies can be used to concentrate drugs in selected target tissues thus minimizing systemic side effects and toxicity. In addition to these therapeutic options, nanoparticle-based "molecular" imaging displays a field in which this new technology has set the stage for an evolutionary leap in diagnostic imaging. Based on the recent progress in nanobiotechnology, nanoparticles have the potential to become useful tools as therapeutic and diagnostic tools in the near future.

Animals↗

PubMed2005

Evaluation of the -26G>A CC16 polymorphism in acute respiratory distress syndrome.

OBJECTIVE: Different risk factors are presumably involved in the pathogenesis of acute respiratory distress syndrome (ARDS) including genetic factors. Clara cell protein 16 (CC16) is a potential candidate gene for ARDS susceptibility because reduced levels of the anti-inflammatory CC16 have been observed in bronchoalveolar lavage fluids or serum of patients with different inflammatory lung diseases. Furthermore, CC16 potently inhibits phospholipase A2, which plays a major role in ARDS pathophysiology. A functional polymorphism (-26G>A) was previously identified and related to decreased CC16 levels, asthma, and asthma severity. DESIGN: Observational study. SETTINGS: Adults with ARDS were recruited from intensive care units in two university medical centers. SUBJECTS: We evaluated the role of this genetic variant in 117 German patients with ARDS and 373 German controls. MEASUREMENTS: The CC16 -26G>A polymorphism was analyzed by melting-curve analysis using a pair of fluorescence resonance energy transfer probes. MAIN RESULTS: CC16 genotype frequencies in ARDS patients did not differ from those seen in controls. Also, the allele frequencies were identical in patients compared with controls (0.66 and 0.34). Moreover, only one of the patients who died (n = 27) was homozygous for the -26A allele. CONCLUSIONS: The CC16 -26G>A polymorphism does not affect the susceptibility to and the outcome of ARDS.

Adolescent↗

PubMed2003

DCL-Hb for trauma patients with severe hemorrhagic shock: the European "On-Scene" multicenter study.

OBJECTIVE: A major cause of death in patients with severe hemorrhagic shock following trauma is the subsequent occurrence of multiple organ failure due to tissue hypoxia. Early administration of an oxygen carrier may reduce the occurrence of organ failures and improve survival. It may also reduce the need of blood products. DESIGN AND SETTING: Prospective multicenter study in a university clinic. PATIENTS: 121 patients with severe hemorrhagic shock. INTERVENTIONS: Patients were randomly assigned "on-scene" to receive either up to 1000 ml of a 10% diaspirin cross-linked hemoglobin (DCLHb) solution or the study center's standard therapy. MEASUREMENTS AND RESULTS: Demographic and physiological characteristics of the two treatment groups at baseline were comparable. Organ failures and survival rates until day 5 and day 28 showed no significant differences. The sponsor therefore terminated this trial prematurely after an interim evaluation of the data indicated no evidence of efficacy to offset concerns raised about the safety of DCLHb. Median volumes of cumulative blood products administered on 1 (1595 vs. 3716 ml) and 7 days (3139 vs. 4746 ml) after admission were lower in the DCLHb group. CONCLUSIONS: The early application of an oxygen carrier (DCLHb) to patients with severe hemorrhagic shock following trauma had no significant effect on the occurrence of organ failure or on 5- and 28-day survival in this abbreviated trial. However, early infusion of up to 1000 ml DCLHb reduces the need for blood products without changing morbidity or survival.

Adolescent↗