28 resultados para Pro-oxidant agent

em Helda - Digital Repository of University of Helsinki


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The purpose of the present study was to evaluate the effects of Lactobacillus helveticus fermented milk (peptide milk) containing the casein-derived tripeptides Isoleucyl-prolyl-proline (Ile-Pro-Pro) and Valyl-prolyl-proline (Val-Pro-Pro) on blood pressure and vascular function in hypertensive subjects. The peptide milk lowered systolic and diastolic blood pressure in long-term use in hypertensive subjects when blood pressure was measured by using 24-hour ambulatory blood pressure measurement (ABPM). The blood pressure lowering effect was seen with the dose of 50 mg of tripeptides, and a tendency for lowering blood pressure was also observed when the dose was 5 mg. No adverse effects compared to the placebo group were reported or detected in laboratory analysis. The effect of the peptide milk on arterial stiffness was shown using two different methods, the ambulatory arterial stiffness index (AASI) and pulse wave analysis (PWA). According to the AASI, arterial stiffness was significantly reduced in the peptide milk group compared to the baseline level, but the difference was not significant compared to the placebo group. PWA showed that the peptide milk reduced arterial stiffness significantly compared to the placebo group. Endothelium-independent relaxation (nitroglycerin) and endothelium-dependent relaxation (salbutamol) did not differ between the groups. The blood pressure lowering mechanisms of the tripeptides and the kinetics of Ile-Pro-Pro were investigated using spontaneously hypertensive rats (SHR) and Sprague-Dawley rats. Previous studies have suggested that the blood pressure lowering effect of the tripeptides Ile-Pro-Pro and Val-Pro-Pro is based on angiotensin-converting enzyme inhibition, but the present findings did not agree with these previous studies. It was shown in SHR that calcium, potassium and magnesium may also have an important role in attenuating the development of hypertension as part of the peptide milk effect. In addition, the present study suggests indirectly that improved endothelial nitric oxide release capacity is not the mechanism by which peptide milk mediates its favourable circulatory effects. The kinetics of Ile-Pro-Pro were studied using adult Sprague-Dawley rats. The results showed that orally administered Ile-Pro-Pro is absorbed at least partly intact from the gastrointestinal tract. Radiolabelled Ile-Pro-Pro was distributed in different tissues and considerable radioactivity levels were found in tissues related to the renin-angiotensin system (RAS), adrenals, aorta and kidneys. Ile-Pro-Pro does not bind to plasma proteins, and therefore it is possible that its blood pressure lowering effect is mediated by free Ile-Pro-Pro. In conclusion, consumption of the peptide milk lowers blood pressure and reduces arterial stiffness in hypertensive subjects. Ile-Pro-Pro can be absorbed partly intact from the gastrointestinal tract and might accumulate in tissues related to the RAS. The precise blood pressure lowering mechanism of peptide milk remains to be studied.

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The biological function of nitric oxide and its oxidized forms has received a great deal of attention over the past two decades. However much less attention has been focused on the reduced nitric oxide, nitroxyl (HNO). Unlike NO, HNO is highly reactive species and thus it needs to be generated by using donor compounds under experimental conditions. Currently there is only one donor available, Angeli s salt, which releases HNO in a controlled fashion under pysiological conditions. Prior studies have shown the pro-oxidative and cytotoxic potential of Angeli s salt compared to NO donors. The high reactivity of HNO with cysteine thiols is considered to form the biochemical basis for its unique properties compared to other nitrogen oxides. Such thiol modification cold result in disturbances of vital cellular functions and subsequently to death of disturbance sensitive cells, such as neurons. Therefore modification of proteins and lipids was studied in vitro and the potential neurotoxicity was studied in vivo by local infusion of Angeli s salt into the rat central nervous system. The results show that under aerobic in vitro conditions, HNO can, subsequent to autoxidation, cause irreversible oxidative modification of proteins and lipids. These effects are not however seen in cell culture or following infusion of Angeli s salt directly into the rat central nervous tissue likely due to presence of lower oxygen and higher thiol concentration. However, due to high reactivity with thiols, HNO can cause irreversible inactivation of cysteine modification sensitive enzymes such as cysteine proteases papain in vitro and cathepsin B in cell culture. Furthermore it was shown that infusion of HNO releasing Angeli s salt into the rat central nervous system causes necrotic cell death and motor dysfunction following infusion into the lumbal intrathecal space. In conclusion, the acute neurotoxic potential of Angeli s salt was shown to be relatively low, but still higher compared to NO donors. HNO was shown to affect numerous cellular processes which could result in neurotoxicity if HNO was produced in vivo.

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Spring barley is the most important crop in Finland based on cultivated land area. Net blotch, a disease caused by Pyrenophora teres Drech., is the most damaging disease of barley in Finland. The pressure to improve the economics and efficiency of agriculture has increased the need for more efficient plant protection methods. Development of durable host-plant resistance to net blotch is a promising possibility. However, deployment of disease resistant crops could initiate selection pressure on the pathogen (P. teres) population. The aim of this study was to understand the population biology of P. teres and to estimate the evolutionary potential of P. teres under selective pressure following deployment of resistance genes and application of fungicides. The study included mainly Finnish P. teres isolates. Population samples from Russia and Australia were also included. Using AFLP markers substantial genotypic variation in P. teres populations was identified. Differences among isolates were least within Finnish fields and significantly higher in Krasnodar, Russia. Genetic differentiation was identified among populations from northern Europe and from Australia, and between the two forms P. teres f. teres (PTT, net form of net blotch) and P. teres f. maculata (PTM, spot form of net blotch) in Australia. Differentiation among populations was also identified based on virulence between Finnish and Russian populations, and based on prochloraz (fungicide) tolerance in the Häme region in Finland. Surprisingly only PTT was recovered from Finland and Russia although both forms were earlier equally common in Finland. The reason for the shift in occurrence of forms in Finland remained uncertain. Both forms were found within several fields in Australia. Sexual reproduction of P. teres was supported by recover of both mating types in equal ratio in those areas although the prevalence of sexual mating seems to be less in Finland than in Australia. Population from Krasnodar was an exception since only one mating type was found in there. Based on the substantial high genotypic variation in Krasnodar it was suggested go represent an old P. teres population, whereas the Australian samples were suggested to represent newer populations. In conclusion, P. teres populations are differentiated at several levels. Human assistance in dispersal of P. teres on infected barley seed is obvious and decreases the differentiation among populations. This can increase the plant protection problems caused by this pathogen. P. teres is capable of sexual reproduction in several areas but the prevalence varies. Based on these findings it is apparent that P. teres has the potential to pose more serious problems in barley cultivation if plant protection is neglected. Therefore, good agricultural practices, including crop rotation and the use of healthy seed, are recommended.

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The agro-environmental subsidy scheme is the most important agricultural environmental policy instrument used in Finland. The principal aim of the agro-environmental subsidy is to reimburse farmer the costs of using environmentally sounder farming practices and the measures that aim for preserving the environment. It also serves as an economic incentive for ensuring the large enough participation. The agro-environmental subsidy scheme is to be reformed in 2007. The main question answered in thesis was that whether farmers in Uusimaa region are ready to participate in the environmental subsidy scheme on the basis of the economical reasons or not. The focus is on farmers' opinions about how difficult it is to carry out measures of new environmental subsidy and do these measures change their ways of farming. The analysis is based on an empirical study of the farmers attitudes towards the new environmental subsidy scheme. The theoretical framework of this thesis is based on principal-agent theory and on the theory of the firm. In principal-agent theory environmental subsidy is interpreted as a deal in which farmers function as agents and government as a principal. Theory of the firm provides a theoretical framework for the analysis, through which we aim to analyse how rationally behaving farmer makes decisions by economical reasons to participate in the environment subsidy scheme. The thesis points out that presumably the participation percentage will stay high during the period of the new environmental subsidy scheme.

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Climate change is the single biggest environmental problem in the world at the moment. Although the effects are still not fully understood and there is considerable amount of uncertainty, many na-tions have decided to mitigate the change. On the societal level, a planner who tries to find an eco-nomically optimal solution to an environmental pollution problem seeks to reduce pollution from the sources where reductions are most cost-effective. This study aims to find out how effective the instruments of the agricultural policy are in the case of climate change mitigation in Finland. The theoretical base of this study is the neoclassical economic theory that is based on the assumption of a rational economic agent who maximizes his own utility. This theoretical base has been widened towards the direction clearly essential to the matter: the theory of environmental eco-nomics. Deeply relevant to this problem and central in the theory of environmental economics are the concepts of externalities and public goods. What are also relevant are the problems of global pollution and non-point-source pollution. Econometric modelling was the method that was applied to this study. The Finnish part of the AGMEMOD-model, covering the whole EU, was used for the estimation of the development of pollution. This model is a seemingly recursive, partially dynamic partial-equilibrium model that was constructed to predict the development of Finnish agricultural production of the most important products. For the study, I personally updated the model and also widened its scope in some relevant matters. Also, I devised a table that can calculate the emissions of greenhouse gases according to the rules set by the IPCC. With the model I investigated five alternative scenarios in comparison to the base-line scenario of Agenda 2000 agricultural policy. The alternative scenarios were: 1) the CAP reform of 2003, 2) free trade on agricultural commodities, 3) technological change, 4) banning the cultivation of organic soils and 5) the combination of the last three scenarios as the maximal achievement in reduction. The maximal achievement in the alternative scenario 5 was 1/3 of the level achieved on the base-line scenario. CAP reform caused only a minor reduction when com-pared to the base-line scenario. Instead, the free trade scenario and the scenario of technological change alone caused a significant reduction. The biggest single reduction was achieved by banning the cultivation of organic land. However, this was also the most questionable scenario to be real-ized, the reasons for this are further elaborated in the paper. The maximal reduction that can be achieved in the Finnish agricultural sector is about 11 % of the emission reduction that is needed to comply with the Kyoto protocol.

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One of the most tangled fields of research is the field of defining and modeling affective concepts, i. e. concepts regarding emotions and feelings. The subject can be approached from many disciplines. The main problem is lack of generally approved definitions. However, e.g. linguists have recently started to check the consistency of their theories with the help of computer simulations. Definitions of affective concepts are needed for performing similar simulations in behavioral sciences. In this thesis, preliminary computational definitions of affects for a simple utility-maximizing agent are given. The definitions have been produced by synthetizing ideas from theories from several fields of research. The class of affects is defined as a superclass of emotions and feelings. Affect is defined as a process, in which a change in an agent's expected utility causes a bodily change. If the process is currently under the attention of the agent (i.e. the agent is conscious of it), the process is a feeling. If it is not, but can in principle be taken into attention (i.e. it is preconscious), the process is an emotion. Thus, affects do not presuppose consciousness, but emotions and affects do. Affects directed at unexpected materialized (i.e. past) events are delight and fright. Delight is the consequence of an unexpected positive event and fright is the consequence of an unexpected negative event. Affects directed at expected materialized (i.e. past) events are happiness (expected positive event materialized), disappointment (expected positive event did not materialize), sadness (expected negative event materialized) and relief (expected negative event did not materialize). Affects directed at expected unrealized (i.e. future) events are fear and hope. Some other affects can be defined as directed towards originators of the events. The affect classification has also been implemented as a computer program, the purpose of which is to ensure the coherence of the definitions and also to illustrate the capabilities of the model. The exact content of bodily changes associated with specific affects is not considered relevant from the point of view of the logical structure of affective phenomena. The utility function need also not be defined, since the target of examination is only its dynamics.

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National identity signifies and makes state s defence- and foreign policy behaviour meaningful. National consciousness is narrated into existence by narratives upon one s own exceptionalism and Otherness of the other nations. While national identity may be understood merely as a self-image of a nation, defence identity refers to the borders of Otherness and issues that have been considered as worth defending for. As national identities and all the world order models are human constructions, they may be changed by the human efforts as well; states and nations may deliberately promote communitarian or even cosmopolitan equality and tolerance without borders of Otherness. The main research question of the thesis is: How does Poland constitute herself as a nation and a state agent in the current world order and to what extent have contextual foreign and defence policy interactions changed the Polish defence identity during the post-Cold War era? The main empirical argument of the thesis is: Poland is a narrated idea of a Christian Catholic nation-state, which the Polish State, the Catholic Church of Poland, the Armed Forces of Poland as well as a majority of the Polish nation share. Polish defence identity has been almost impenetrable to contextual foreign and defence policy interactions during the post-Cold War era. While Christian religious ontology binds corporate Poland together, allowing her to survive any number of military and political catastrophes, it simultaneously brings her closer to the USA, raises tensions in the infidel EU-context, and restrains corporate Poland s pursuit of communitarian, or even cosmopolitan, global equality and tolerance. It is not the case that corporate Poland s foreign and defence policy orientation is instinctively Atlanticist by nature, as has been argued. Rather, it has been the State s rational project to overcome a habituated and reified fear of becoming geopolitically sandwiched between Russian and German Others by leaning on the USA; among the Polish nation, support for the USA has been declining since 2004. It is not corporate Poland either that has turned into a constructive European , as has been argued, but rather the Polish nation that has, at least partly, managed to emancipate itself from its habituation to a betrayal by Europe narrative, since it favours the EU as much as it favours NATO. It seems that in the Polish case a truly common European CFSP vis-à-vis Russia may offer a solution that will emancipate the Polish State from its habituated EU-sceptic role identity and corporate Poland from its narrated borders of Otherness towards Russia and Germany, but even then one cannot be sure whether any other perspective than the Polish one on a common stand towards Russia would satisfy the Poles themselves.

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Kielet saksa ja ruotsi. Nimiösivulla teksti Helsingforsiae 1924-27.

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Kielet saksa ja ruotsi. Nimiösivulla teksti Helsingforsiae 1924-29.

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Kielet suomi ja saksa. Nimiösivulla teksti Helsingforsiae 1935-36.

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Kielet saksa ja ruotsi.

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Kielet saksa ja ruotsi.