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Search Results: 1 - 10 of 14766 matches for " Christian Burvenich "
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Chemical-Functional Diversity in Cell-Penetrating Peptides
Sofie Stalmans, Evelien Wynendaele, Nathalie Bracke, Bert Gevaert, Matthias D’Hondt, Kathelijne Peremans, Christian Burvenich, Bart De Spiegeleer
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071752
Abstract: Cell-penetrating peptides (CPPs) are a promising tool to overcome cell membrane barriers. They have already been successfully applied as carriers for several problematic cargoes, like e.g. plasmid DNA and (si)RNA, opening doors for new therapeutics. Although several hundreds of CPPs are already described in the literature, only a few commercial applications of CPPs are currently available. Cellular uptake studies of these peptides suffer from inconsistencies in used techniques and other experimental conditions, leading to uncertainties about their uptake mechanisms and structural properties. To clarify the structural characteristics influencing the cell-penetrating properties of peptides, the chemical-functional space of peptides, already investigated for cellular uptake, was explored. For 186 peptides, a new cell-penetrating (CP)-response was proposed, based upon the scattered quantitative results for cellular influx available in the literature. Principal component analysis (PCA) and a quantitative structure-property relationship study (QSPR), using chemo-molecular descriptors and our newly defined CP-response, learned that besides typical well-known properties of CPPs, i.e. positive charge and amphipathicity, the shape, structure complexity and the 3D-pattern of constituting atoms influence the cellular uptake capacity of peptides.
Stability-indicating HPLC-DAD/UV-ESI/MS impurity profiling of the anti-malarial drug lumefantrine
Mathieu Verbeken, Sultan Suleman, Bram Baert, Elien Vangheluwe, Sylvia Van Dorpe, Christian Burvenich, Luc Duchateau, Frans H Jansen, Bart De Spiegeleer
Malaria Journal , 2011, DOI: 10.1186/1475-2875-10-51
Abstract: Using HPLC-DAD/UV-ESI/ion trap/MS, a comprehensive impurity profile was established based upon analysis of market samples as well as stress, accelerated and long-term stability results. In-silico toxicological predictions for these lumefantrine related impurities were made using Toxtree? and Derek?.Several new impurities are identified, of which the desbenzylketo derivative (DBK) is proposed as a new specified degradant. DBK and the remaining unspecified lumefantrine related impurities are predicted, using Toxtree? and Derek?, to have a toxicity risk comparable to the toxicity risk of the API lumefantrine itself.From unstressed, stressed and accelerated stability samples of lumefantrine API and FPPs, nine compounds were detected and characterized to be lumefantrine related impurities. One new lumefantrine related compound, DBK, was identified and characterized as a specified degradation impurity of lumefantrine in real market samples (FPPs). The in-silico toxicological investigation (Toxtree? and Derek?) indicated overall a toxicity risk for lumefantrine related impurities comparable to that of the API lumefantrine itself.Lumefantrine (benflumetol) is a 2,4,7,9-substituted fluorene (2,3-benzindene) derivative (Figure 1). It was synthesized in the 1970s by the Academy of Military Medical Sciences, in Beijing, and registered in China for anti-malarial use in 1987. It is now commercially available in fixed combination products, mostly with β-artemether (ACT, artemisinin-based combination therapy), which are proven to be highly efficacious for treatment of uncomplicated falciparum malaria. In addition to the compound itself, the compound proved to possess marked blood schizontocidal activity against a wide range of Plasmodium, among them chloroquine-resistant Plasmodium falciparum [1-5].Biochemical studies suggest that its anti-malarial effect involves lysosomal trapping of the drug in the food vacuole of the intra-erythrocytic parasite, followed by binding to haem that
Variation of inflammatory dynamics and mediators in primiparous cows after intramammary challenge with Escherichia coli
Adel Pezeshki, Philippe Stordeur, Hugues Wallemacq, Frédéric Schynts, Mieke Stevens, Philippe Boutet, Luc J Peelman, Bart De Spiegeleer, Luc Duchateau, Fabrice Bureau, Christian Burvenich
Veterinary Research , 2011, DOI: 10.1186/1297-9716-42-15
Abstract: The severity of coliform mastitis is of much more concern than its incidence [1]. Pathogen, cow and environment are three interdependent factors which influence the mastitis susceptibility [1]. From the various bacterial virulence factors studied during Escherichia coli mastitis [2], only a few have been found to play an important role in the outcome of the disease. It has been accepted that the type of E. coli strain is not the main factor in classification of severity. Preventive treatments which are efficient against contagious mastitis have been shown to be inefficient in the control of E. coli mastitis [3]. The severity of bovine E. coli mastitis is mainly determined by cow factors rather than by the pathogenecity of the invading pathogen and management [1]. It is known that the growth of E. coli in the udder cistern is specially related with the period of lactation and parity of cows. E. coli mastitis with severe clinical symptoms is more frequently observed around calving and during early lactation in dairy cows, whereas symptoms are mild to moderate during mid and late lactation. Because of hormonal, metabolic and nutritional alterations associated with pregnancy, immune system is compromised around calving (reviewed by Pezeshki et al. [4]). Cow parity is another important physiological factor that influences the severity of clinical coliform mastitis [5,6]. Clinical severe cases of coliform mastitis are mostly seen among multiparous cows rather than primiparous cows during early lactation. To our best knowledge the inflammatory status of primiparous cows ranking based on severity after intramammary infection of E. coli is poorly understood during early lactation. Physiological factors have been mainly studied in multiparous cows ranging from second lactation to sixth lactation [6-10].Thromboxanes (TX), prostaglandins (PG), leukotriens (LT) and lipoxines (LX) which are the enzymatically generated products of cyclooxygenases (COX) and lipoxygenases are genera
Role of Estradiol, Progestins, Insulines and Adipocytokines in Breast Cancer Promotion in Post-Menopausal Women  [PDF]
Christian Jamin
Journal of Cancer Therapy (JCT) , 2010, DOI: 10.4236/jct.2010.11007
Abstract: Estrogens and artificial progestins used in hormone replacement therapy increase breast cancer risk. This seems to bedue to a promoting and not initiating effect. A synergic effect of estradiol and hyperinsulinism has been shown. Insulinplays a role in the increase of breast cancer risk when associated with android obesity, sedentariness, type II diabetes,and high glycemic index food, alcohol and trans fatty acids intake. Natural menopause induces insulin resistance anddoes not induce a risk decrease. The role of insulin gives a new outlook on the influence of HRT in breast cancer promotion:estradiol alone, which improves insulin-sensitivity, does not increase breast cancer risk. Artificial progestinsassociated with estrogens increase the risk, whereas estrogens associated with progesterone do not. This could be dueto the fact that artificial progestins increase insulin resistance, whereas natural progesterone does not. Adipose tissue,which is an endocrine gland, is insulin dependant. Breast cancer and its seriousness are correlated to adipocytokincirculating levels such as resistin, leptin, interleukin 1, adipocyte fatty acid-binding protein, and are inversely correlatedto the level of adiponectin. Insulin could play a synergic role with sexual steroids by a direct effect and by increasingadipose tissue secretions.
The Timeliness of Direct Democracy in the EU—The Example of Nuclear Energy in the EU and the Institutionalisation of the European Citizens’ Initiative in the Lisbon Treaty  [PDF]
Christian Joerges
Beijing Law Review (BLR) , 2012, DOI: 10.4236/blr.2012.31001
Abstract: The catastrophic nuclear incident in Fukushima in March 2011 has shocked Europe. Its impact was particularly strong in Germany with its decade-old anti-nuclear movements. Political and technological re-orientations were initiated in that country without considering at any depth the potential of European law and politics to control or obstruct such moves. Somewhat paradoxically, the Euratom Treaty of 1957 and also the new Treaty of Lisbon confirm the right of each Member State to decide upon the use of nuclear energy autonomously. This means that European citizens remain exposed to the risks of that technology until the highly unlikely consent of all Member States to abstain from its further use. That constellation poses a dilemma for democracy because it implies that each political decision taken within parts of the Union exerts external pan-European effects. The article considers the chances for an inclusive democratic process which would lead to a legitimated European decision. It examines the possibilities offered by the new European Citizens Initiative which the Lisbon Treaty has institutionalized in its Article 12 and concludes that this instrument could indeed be used to instigate a European-wide debate which may eventually lead to pertinent changes in the Treaties.
The Methodological Implications of the Schutz-Parsons Debate  [PDF]
Christian Etzrodt
Open Journal of Philosophy (OJPP) , 2013, DOI: 10.4236/ojpp.2013.31006
Abstract:

The aim of this paper is an analysis of the different standpoints of Parsons and Schutz concerning Weber’s suggestion that sociological explanations have to include the subjective point of view of the actors, the Cartesian Dilemma that the actor’s consciousness is not accessible to the researcher, and the Kantian Problem that theories are necessary in order to interpret sensory data, but that there is no guarantee that these theories are true. The comparison of Schutz’s and Parsons’s positions shows that Parsons’s methodology is na?ve and unsuitable for a sociological analysis. But although Schutz’s methodological standpoint is much more reasonable, it is also problematic, because it excludes highly abstract social “facts” such as social systems from the research agenda. Parsons can deal with such highly abstract facts, despite the drawback that with his methodology the truth content of theories cannot be judged.

Psychodynamic Positive Psychotherapy Emphasizes the Impact of Culture in the Time of Globalization  [PDF]
Christian Henrichs
Psychology (PSYCH) , 2012, DOI: 10.4236/psych.2012.312A169
Abstract:

The emphasis of Positive Psychotherapy on culture is a specific contribution to psychodynamic psycho- therapy and to contemporary psychological reasoning and intervention in general. In this article, it is argued that a consistent psycho-cultural perspective as introduced by the founder of Positive Psychotherapy, the Persian-German psychiatrist and psychotherapist Nossrat Peseschkian (1933-2010), is beneficial for humanity’s psychological needs in the time of globalization. Also elementary concepts and the style of intervention in Positive Psychotherapy are described.


Conservation of Gravitational Energy-Momentum and Inner Diffeomorphism Group Gauge Invariance  [PDF]
Christian Wiesendanger
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.48A006
Abstract:

Viewing gravitational energy momentum \"\" as equal by observation, but different in essence from inertial energy-momentum \"\" requires two different symmetries to account for their independent conservations—spacetime and inner translation invariance. Gauging the latter a generalization of non-Abelian gauge theories of compact Lie groups is developed resulting in the gauge theory of the non-compact group of volume-preserving diffeomorphisms of an inner Minkowski space M4. As usual the gauging requires the introduction of a covariant derivative, a gauge field and a field strength operator. An invariant and minimal gauge field Lagrangian is derived. The classical field dynamics and the conservation laws for the new gauge theory are developed. Finally, the theorys Hamiltonian in the axial gauge is expressed by two times six unconstrained independent canonical variables obeying the usual Poisson brackets and the positivity of the Hamiltonian is related to a condition on the support of the gauge fields.

Conservation of Gravitational Energy Momentum and Renormalizable Quantum Theory of Gravitation  [PDF]
Christian Wiesendanger
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.48A013
Abstract:

Viewing gravitational energy-momentum as equal by observation, but different in essence from inertial energymomentum \"\" naturally leads to the gauge theory of volume-preserving diffeomorphisms of an inner Minkowski space \"\" which can describe gravitation at the classical level. This theory is quantized in the path integral formalism starting with a non-covariant Hamiltonian formulation with unconstrained canonical field variables and a manifestly positive Hamiltonian. The relevant path integral measure and weight are then brought into a Lorentz- and gauge-covariant form allowing to express correlation functions—applying the De Witt-Faddeev-Popov approach—in any meaningful gauge. Next the Feynman rules are developed and the quantum effective action at one loop in a background field approach is renormalized which results in an asymptotically free theory without presence of other fields and in a theory without asymptotic freedom including the Standard Model (SM) fields. Finally the BRST apparatus is developed as preparation for the renormalizability proof to all orders and a sketch of this proof is given.

General Relativity as the Classical Limit of the Renormalizable Gauge Theory of Volume Preserving Diffeomorphisms  [PDF]
Christian Wiesendanger
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.510098
Abstract:

The different roles and natures of spacetime appearing in a quantum field theory and in classical physics are analyzed implying that a quantum theory of gravitation is not necessarily a quantum theory of curved spacetime. Developing an alternative approach to quantum gravity starts with the postulate that inertial energy-momentum and gravitational energy-momentum need not be the same for virtual quantum states. Separating their roles naturally leads to the quantum gauge field theory of volume-preserving diffeomorphisms of an inner four-dimensional space. The classical limit of this theory coupled to a quantized scalar field is derived for an on-shell particle where inertial energy-momentum and gravitational energy-momentum coincide. In that process the symmetry under volume-preserving diffeomorphisms disappears and a new symmetry group emerges: the group of coordinate transformations of four-dimensional spacetime and with it General Relativity coupled to a classical relativistic point particle.

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