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Search Results: 1 - 10 of 122 matches for " Boguslaw Lipinski "
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Hydroxyl Radical and Its Scavengers in Health and Disease
Boguslaw Lipinski
Oxidative Medicine and Cellular Longevity , 2011, DOI: 10.1155/2011/809696
Abstract: It is generally believed that diseases caused by oxidative stress should be treated with antioxidants. However, clinical trials with such antioxidants as ascorbic acid and vitamin E, failed to produce the expected beneficial results. On the other hand, important biomolecules can be modified by the introduction of oxygen atoms by means of non-oxidative hydroxyl radicals. In addition, hydroxyl radicals can reduce disulfide bonds in proteins, specifically fibrinogen, resulting in their unfolding and scrambled refolding into abnormal spatial configurations. Consequences of this reaction are observed in many diseases such as atherosclerosis, cancer and neurological disorders, and can be prevented by the action of non-reducing substances. Moreover, many therapeutic substances, traditionally classified as antioxidants, accept electrons and thus are effective oxidants. It is described in this paper that hydroxyl radicals can be generated by ferric ions without any oxidizing agent. In view of the well-known damaging effect of poorly chelated iron in the human body, numerous natural products containing iron binding agents can be essential in the maintenance of human health. However, beneficial effects of the great number of phytochemicals that are endowed with hydroxyl radical scavenging and/or iron chelating activities should not be considered as a proof for oxidative stress.
Hydroxyl Radical and Its Scavengers in Health and Disease
Boguslaw Lipinski
Oxidative Medicine and Cellular Longevity , 2011, DOI: 10.1155/2011/809696
Abstract: It is generally believed that diseases caused by oxidative stress should be treated with antioxidants. However, clinical trials with such antioxidants as ascorbic acid and vitamin E, failed to produce the expected beneficial results. On the other hand, important biomolecules can be modified by the introduction of oxygen atoms by means of non-oxidative hydroxyl radicals. In addition, hydroxyl radicals can reduce disulfide bonds in proteins, specifically fibrinogen, resulting in their unfolding and scrambled refolding into abnormal spatial configurations. Consequences of this reaction are observed in many diseases such as atherosclerosis, cancer and neurological disorders, and can be prevented by the action of non-reducing substances. Moreover, many therapeutic substances, traditionally classified as antioxidants, accept electrons and thus are effective oxidants. It is described in this paper that hydroxyl radicals can be generated by ferric ions without any oxidizing agent. In view of the well-known damaging effect of poorly chelated iron in the human body, numerous natural products containing iron binding agents can be essential in the maintenance of human health. However, beneficial effects of the great number of phytochemicals that are endowed with hydroxyl radical scavenging and/or iron chelating activities should not be considered as a proof for oxidative stress. 1. Introduction It is commonly believed that the in vivo damage of biomolecules is initiated by reactive oxygen species (ROS) in a process known as oxidative stress. However, oxidation reaction in biological systems may also occur via a nonradical pathway, for example, by hydrogen peroxide. In such cases, the products of its action are molecules that are enriched in one or more oxygen atoms that are generally considered to be markers of oxidative stress. Yet mere presence of extra oxygen does not tell us whether a given product is generated by a single- (free radical) or two-electron oxidation reaction. It should be emphasized that, according to the concept of oxidative stress, peroxidation and degradation of vulnerable biological molecules is caused by oxygen-centered radicals generated, in turn, by excessive blood oxygenation. However, this conclusion is based on studies of ischemia/reperfusion cases in which periods of prolonged hypoxia are followed by a sudden supply of oxygen. For example, in patients with extracorporeal circulation the appearance of lipid and/or nucleic acids oxidation products is accepted as signs of oxidative stress. However, a very important fact is being
The Role of Iron-Induced Fibrin in the Pathogenesis of Alzheimer’s Disease and the Protective Role of Magnesium
Boguslaw Lipinski,Etheresia Pretorius
Frontiers in Human Neuroscience , 2013, DOI: 10.3389/fnhum.2013.00735
Abstract: Amyloid hypothesis of Alzheimer’s disease (AD) has recently been challenged by the increasing evidence for the role of vascular and hemostatic components that impair oxygen delivery to the brain. One such component is fibrin clots, which, when they become resistant to thrombolysis, can cause chronic inflammation. It is not known, however, why some cerebral thrombi are resistant to the fibrinolytic degradation, whereas fibrin clots formed at the site of vessel wall injuries are completely, although gradually, removed to ensure proper wound healing. This phenomenon can now be explained in terms of the iron-induced free radicals that generate fibrin-like polymers remarkably resistant to the proteolytic degradation. It should be noted that similar insoluble deposits are present in AD brains in the form of aggregates with Abeta peptides that are resistant to fibrinolytic degradation. In addition, iron-induced fibrin fibers can irreversibly trap red blood cells (RBCs) and in this way obstruct oxygen delivery to the brain and induce chronic hypoxia that may contribute to AD. The RBC-fibrin aggregates can be disaggregated by magnesium ions and can also be prevented by certain polyphenols that are known to have beneficial effects in AD. In conclusion, we argue that AD can be prevented by: (1) limiting the dietary supply of trivalent iron contained in red and processed meat; (2) increasing the intake of chlorophyll-derived magnesium; and (3) consumption of foods rich in polyphenolic substances and certain aliphatic and aromatic unsaturated compounds. These dietary components are present in the Mediterranean diet known to be associated with the lower incidence of AD and other degenerative diseases.
Profound Morphological Changes in the Erythrocytes and Fibrin Networks of Patients with Hemochromatosis or with Hyperferritinemia, and Their Normalization by Iron Chelators and Other Agents
Etheresia Pretorius, Janette Bester, Natasha Vermeulen, Boguslaw Lipinski, George S. Gericke, Douglas B. Kell
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0085271
Abstract: It is well-known that individuals with increased iron levels are more prone to thrombotic diseases, mainly due to the presence of unliganded iron, and thereby the increased production of hydroxyl radicals. It is also known that erythrocytes (RBCs) may play an important role during thrombotic events. Therefore the purpose of the current study was to assess whether RBCs had an altered morphology in individuals with hereditary hemochromatosis (HH), as well as some who displayed hyperferritinemia (HF). Using scanning electron microscopy, we also assessed means by which the RBC and fibrin morphology might be normalized. An important objective was to test the hypothesis that the altered RBC morphology was due to the presence of excess unliganded iron by removing it through chelation. Very striking differences were observed, in that the erythrocytes from HH and HF individuals were distorted and had a much greater axial ratio compared to that accompanying the discoid appearance seen in the normal samples. The response to thrombin, and the appearance of a platelet-rich plasma smear, were also markedly different. These differences could largely be reversed by the iron chelator desferal and to some degree by the iron chelator clioquinol, or by the free radical trapping agents salicylate or selenite (that may themselves also be iron chelators). These findings are consistent with the view that the aberrant morphology of the HH and HF erythrocytes is caused, at least in part, by unliganded (‘free’) iron, whether derived directly via raised ferritin levels or otherwise, and that lowering it or affecting the consequences of its action may be of therapeutic benefit. The findings also bear on the question of the extent to which accepting blood donations from HH individuals may be desirable or otherwise.
Changes in red blood cell membrane structure in type 2 diabetes: a scanning electron and atomic force microscopy study
Antoinette V Buys, Mia-Jean Van Rooy, Prashilla Soma, Dirk Van Papendorp, Boguslaw Lipinski, Etheresia Pretorius
Cardiovascular Diabetology , 2013, DOI: 10.1186/1475-2840-12-25
Abstract:
Anregungen zur Darstellung von Routineformeln in einsprachigen Lernerw rterbüchern für DaF
Lipinski; Silke
Linguistik Online , 2011,
Abstract: Routine formulas (RFs) carry many functions in a language system. Thus, not only knowing them but also mastering their use is of major importance for the L2-learner. For this reason, it is important to also describe RFs adequately in learners' dictionaries. However, as previous research shows, there is a major discrepancy between lexicographical requirements and reality. Some demands for the way in which RFs should be presented can be derived from the list of criteria which are used to evaluate dictionary entries of RFs. Some of these requirements may be called phraseographical minima, the realization of some other requirements that have yet to be developed in detail. This article intends to show options on how to improve the lexicography of RFs in print dictionaries for L2-learners. Suggestions for the presentation of RFs in the lexicographical macro-, micro-, and medio-structure are made and discussed.
Stability of routing strategies for the maximum lifetime problem in ad-hoc wireless networks
Z. Lipinski
Computer Science , 2014,
Abstract: We solve the maximum lifetime problem for a one-dimensional, regular ad-hoc wireless network with one data collector $L_N$ for any data transmission cost energy matrix which elements $E_{i,j}$ are superadditive functions, i.e., satisfy the inequality $\forall_{i\leq j\leq k}\;E_{i,j}+E_{j,k}\leq E_{i,k}$. We analyze stability of the solution under modification of two sets of parameters, the amount of data $Q_i$, $i\in [1,N]$ generated by each node and location of the nodes $x_i$ in the network. We assume, that the data transmission cost energy matrix $E_{i,j}$ is a function of a distance between network nodes and thus the change of the node location causes change of $E_{i,j}$. We say, that a solution $q(t_0)$ of the maximum network lifetime problem is stable under modification of a given parameter $t_0$ in the stability region $U(t_0)$, if the data flow matrix $q(t)$ is a solution of the problem for any $t\in U(t_0)$. In the paper we estimate the size of the stability region $U(Q^0,d^0)$ for the solution of the maximum network lifetime problem for the $L_N$ network in the neighborhoods of the points $Q^0_i=1$, $d^0_i=0$, where $d_i\in (-1,1)$ describes the shift of the nodes from their initial location $x_i^0=i$, i.e., $x_i=i-d_i$.
PANORAMIC VIEW ON JAN VANKMAJER'S CREATIVE OUTPUT
Boguslaw Zmudzinski
Studia Humanistyczne (Kraków. 2003) , 2007,
Abstract: Jan vankmajer - is a leading world animation creator and confirmed representative representative of surrealism belonging to a small circle of film arts who, apart from great achievements in short animation, can also boast of remarkable attainments in long features. He owes it to his technique of combining animated and acting scenes together, which he developed already when making his short film forms. The article is a synthetic attempt at presentation of the artist's whole creative output starting from his first short animations from the 1960s up to his latest feature film titled Lunacy. The author of the text underlines the centrality of the object animation in the artistic work of Jan vankmajer, who is the most outstanding representative of this form of animation alongside Jan Lenica, Walerian Borowczyk and Stephen and Timopthy Quay. In his latest film, the artist suggest with the kind of determination typical of the surrealists that all of his object animation production can be regarded as vision of a lunatic. Not many artist have courage to do so in the contemporary - and commercialized in the very nature of it - audiovisual culture.
Chern-Simons approach to three-manifold invariants
Boguslaw Broda
Physics , 1993, DOI: 10.1142/S0217732395000521
Abstract: % A new, formal, non-combinatorial approach to invariants of % three-dimensional manifolds of Reshetikhin, Turaev and % Witten in the framework of non-perturbative topological % quantum Chern-Simons theory, corresponding to an arbitrary % compact simple Lie group, is presented. A direct % implementation of surgery instructions in the context of % quantum field theory is proposed. An explicit form of the % specialization of the invariant to the group SU(2) is % derived, and shown to agree with the result of Lickorish. % % AMS subject classifications (1991): 57M25, 57N10, 57R65, 81T13.
Chern-Simons approach to three-manifold invariants
Boguslaw Broda
Physics , 1993,
Abstract: A new, formal, non-combinatorial approach to invariants of three-dimensional manifolds of Reshetikhin, Turaev and Witten in the framework of non-perturbative topological quantum Chern-Simons theory, corresponding to an arbitrary compact simple Lie group, is presented. A direct implementation of surgery instructions in the context of quantum field theory is proposed. An explicit form of the specialization of the invariant to the group SU(2) is derived.
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