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Search Results: 1 - 10 of 1419 matches for " Frederik Jozef Vernimmen "
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Technological Progress in Radiation Therapy for Brain Tumors  [PDF]
Frederik Jozef Vernimmen, Kathy Rock
Journal of Cancer Therapy (JCT) , 2014, DOI: 10.4236/jct.2014.51005
Abstract:

To achieve a good therapeutic ratio the radiation dose to the tumor should be as high as possible with the lowest possible dose to the surrounding normal tissue. This is especially the case for brain tumors. Technological advancements in diagnostic imaging, dose calculations, and radiation delivery systems, combined with a better understanding of the pathophysiology of brain tumors have led to improvements in the therapeutic results. The widely used technology of delivering 3-D conformal therapy with photon beams (gamma rays) produced by Linear Accelerators has progressed into the use of Intensity modulated radiation therapy (IMRT). Particle beams have been used for several decades for radiotherapy because of their favorable depth dose characteristics. The introduction of clinically dedicated proton beam therapy facilities has improved the access for cancer patients to this treatment. Proton therapy is of particular interest for pediatric malignancies. These technical improvements are further enhanced by the evolution in tumor physiology imaging which allows for improved delineation of the tumor. This in turn opens the potential to adjust the radiation dose to maximize the radiobiological effects. The advances in both imaging and radiation therapy delivery will be discussed.

Gold Nanoparticles in Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations  [PDF]
Frederik Vernimmen, Mikhail L. Shmatov
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2015, DOI: 10.4236/jbnb.2015.63019
Abstract: Objective of the study: To explore the potential for therapeutic gain with gold nanoparticles in arteriovenous malformation radiosurgery based on their interaction with photons and protons. Study methods: Radiation dose enhancement resulting from the interaction of gold nanoparticles with irradiation ranging from kilovoltage to megavoltage photons and protons was researched in the literature. The role of angiogenesis and its regulation via vascular endothelial growth factors and cell membrane receptors, especially for endothelial cells in arteriovenous malformations, was investigated as a way for selective arteriovenous malformation deposition. Results: Radiation dose enhancement with gold nanoparticles is described in the literature but has so far only been investigated for its potential in treating malignancies. Because of the high atomic number of gold (Z = 79), dose enhancement occurs with photons mainly based on secondary photon and Auger electron production and the dose enhancement factor is the highest for irradiation with kilo voltage photons. Dose enhancement happens with megavoltage photons also but to a lesser extend and is mainly due to the ionization of gold by secondary photons and electrons generated by the megavoltage photons passing through tissue. The range of the secondary photo electrons emitted by gold is sufficient to cover the entire endothelial cell content. Protons interact with the production of Auger electrons which have a very short range, insufficient to cover the entire contents of endothelial cells, but sufficient to cause a high cell membrane dose for membrane located gold nanoparticles (AuNPs). Arteriovenous malformations are dynamic entities with angiogenesis taking place. This is reflected by a different expression of angiogenic receptors on the membrane of arteriovenous malformation endothelial cells compared to normal brain blood vessels, thereby opening the opportunity for selective deposition of such particles. For the use in proton therapy a new definition for the dose enhancement factor describing the local effect of nanoparticles is proposed. Conclusion: The concept of nanoparticle enhanced radiosurgery for arteriovenous malfor-mations by selective deposition of gold nanoparticles is a novel approach. The local dose enhancement opens the way for therapeutic gain which in turn could lead to improved obliteration rates and/or a shorter latent period.
Uncovering Enhancer Functions Using the α-Globin Locus
Douglas Vernimmen
PLOS Genetics , 2014, DOI: doi/10.1371/journal.pgen.1004668
Abstract: Over the last three decades, studies of the α- and β-globin genes clusters have led to elucidation of the general principles of mammalian gene regulation, such as RNA stability, termination of transcription, and, more importantly, the identification of remote regulatory elements. More recently, detailed studies of α-globin regulation, using both mouse and human loci, allowed the dissection of the sequential order in which transcription factors are recruited to the locus during lineage specification. These studies demonstrated the importance of the remote regulatory elements in the recruitment of RNA polymerase II (PolII) together with their role in the generation of intrachromosomal loops within the locus and the removal of polycomb complexes during differentiation. The multiple roles attributed to remote regulatory elements that have emerged from these studies will be discussed.
Synthesis and catalytic applications of combined zeolitic/mesoporous materials
Jarian Vernimmen,Vera Meynen,Pegie Cool
Beilstein Journal of Nanotechnology , 2011, DOI: 10.3762/bjnano.2.87
Abstract: In the last decade, research concerning nanoporous siliceous materials has been focused on mesoporous materials with intrinsic zeolitic features. These materials are thought to be superior, because they are able to combine (i) the enhanced diffusion and accessibility for larger molecules and viscous fluids typical of mesoporous materials with (ii) the remarkable stability, catalytic activity and selectivity of zeolites. This review gives an overview of the state of the art concerning combined zeolitic/mesoporous materials. Focus is put on the synthesis and the applications of the combined zeolitic/mesoporous materials. The different synthesis approaches and formation mechanisms leading to these materials are comprehensively discussed and compared. Moreover, Ti-containing nanoporous materials as redox catalysts are discussed to illustrate a potential implementation of combined zeolitic/mesoporous materials.
Cloning, expression, purification and characterization of replication protein from plasmid pGP2 from Acetobacter estunensis  [PDF]
Peter Grones, Jozef Grones
Advances in Bioscience and Biotechnology (ABB) , 2010, DOI: 10.4236/abb.2010.15055
Abstract: The Acetobacter estunensis Rep34 protein participates in the replication of bacterial plasmid pGP2. The Rep34 protein of the A. estunensis, was cloned to the expression vector, that ensure fusion with a His-tag sequence (Rep34 His-tagged), over-expressed in Escherichia coli and purified by metal-affinity chromatography to yield a highly purified and active protein. On this purified protein number different activities and motifs were detected. DNA band-shift assays showed that the Rep34 His-tagged protein bound to the regulation region for replication on the linear double-stranded DNA. In the protein was determined phosphatase activity, ATPase activity and protein is possible to unwind double strand DNA.
Effect of external electric field upon charge distribution, energy and dipole moment of selected monosaccharide molecules  [PDF]
Jozef Mazurkiewicz, Piotr Tomasik
Natural Science (NS) , 2012, DOI: 10.4236/ns.2012.45040
Abstract: External electric field of 0.001, 0.01 and 0.05 a.u. changes distribution of the electron density in α- and β-D-glucose, α- and β-D-galactose, α- and β-fructopyranoses and α- and β-fructofuranoses, α- and β-D-ribofuranoses and α and β-D-xylo- furanoses. Hyper-Chem 8.0 software was used together with the AM1 method for optimization of the conformation of the molecules of monosaccharides under study. Then polarizability, charge distribution, potential and dipole moment for molecules placed in the external electric field of 0.000, 0.001, 0.01 and 0.05 a.u. were calculated involving DFT 3-21G method. Application of the external field induced polarizability of electrons, atoms and dipoles, the latter resulting in eventual reorientation of the molecules along the applied field of the molecules and the electron density redistribution at particular atoms. Increase in the field strength generated mostly irregular changes of the electron densities at particular atoms of the molecules as well as polarizabilities. Energy of these molecules and their dipole moments also varied with the strength of the field applied. Results of computations imply that saccharides present in the living organisms may participate in the response of the living organisms to the external electric field affecting metabolism of the molecules in the body fluids by fitting molecules to the enzymes. Structural changes of saccharide components of the membranes can influence the membrane permeability.
Unni From og Nete N rgaard Kristensen (red.): Proces og struktur i ph.d.-forl bet - om at leve og overleve
Frederik Hertel
MedieKultur : Journal of Media and Communication Research , 2007,
Abstract:
On Derksen’s law and related issues
Frederik Kortlandt
Baltistica , 2012,
Abstract:
On the orthography of the Old Prussian texts
Frederik Kortlandt
Baltistica , 2011,
Abstract:
Dominance and monophtongization: method versus insight
Frederik Kortlandt
Baltistica , 2012,
Abstract:
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