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11222. Variability of Mammary Carcinogenesis Induction in Female Sprague-Dawley and Wistar:Han Rats: the Effect of Season and Age

Creator:
Kubatka, P., Eva Ahlersová, Ivan Ahlers, Bianka Bojková, Kalická, K., Eva Adámeková, Marková, M., Chamilová, M., and Čermáková, M.
Format:
print, bez média, and svazek
Type:
article, studie, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Mammary carcinogenesis, Seasons, Critical periods, Rat strains, Susceptibility, 14, and 612
Language:
English
Description:
It is important to determine and clarify the variability of mammary carcinogenesis induction in animal experimental studies particularly in connection with chemoprevention projects. The circannual seasonal rhythms of hormone levels or various parameters within the immune system may involve factors participating in mammary gland carcinogenesis. In our study, 19 experiments were conducted and all of them lasted for about 25 weeks after chemical carcinogen administration (DMBA or NMU) under standard laboratory conditions. Females of two rat strains - a medium susceptible Sprague-Dawley strain and a very low susceptible Wistar:Han were used. We observed not only the effect of seasonal changes but also the effect of age after single or repeated carcinogen administration. The seasonal dependence of mammary carcinogenesis with higher tumor incidence during long days in comparison with winter short days has been demonstrated in Sprague-Dawley rats. In experiments on the Wistar:Han strain, certain features of seasonal character were recorded, although the very low susceptibility of this strain to mammary carcinogenesis might have influenced the results. A limited period of carcinogen administration in early puberty around postnatal days 43-46 (higher susceptibility), when compared to the period after postnatal day 50, is the factor significantly increasing incidence and frequency of mammary carcinogenesis in the Sprague-Dawley strain. Our results indicate the need to consider the effect of season and age of animals at the time of carcinogen administration on rat mammary carcinogenesis induction. However, the application of the results obtained in one strain of experimental animals may only lead to misleading conclusions., P. Kubatka, E. Ahlersová, I. Ahlers, B. Bojková, K. Kalická, E. Adámeková, M. Marková, M. Chamilová, M. Čermáková., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

11223. Variability of mitochondrial respiration in relation to sepsis-induced multiple organ dysfunction

Creator:
Kohoutová, M., Dejmek, J., Tůma, Z., and Kuncová, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
sepsis, mitochondria, oxygen consumption, multiple organ dysfunction, and animal models
Language:
English
Description:
Ample experimental evidence suggests that sepsis could interfere with any mitochondrial function; however, the true role of mitochondrial dysfunction in the pathogenesis of sepsis-induced multiple organ dysfunction is still a matter of controversy. This review is primarily focused on mitochondrial oxygen consumption in various animal models of sepsis in relation to human disease and potential sources of variability in experimental results documenting decrease, increase or no change in mitochondrial respiration in various organs and species. To date, at least three possible explanations of sepsis-associated dysfunction of the mitochondrial respiratory system and consequently impaired energy production have been suggested: 1. Mitochondrial dysfunction is secondary to tissue hypoxia. 2. Mitochondria are challenged by various toxins or mediators of inflammation that impair oxygen utilization (cytopathic hypoxia). 3. Compromised mitochondrial respiration could be an active measure of survival strategy resembling stunning or hibernation. To reveal the true role of mitochondria in sepsis, sources of variability of experimental results based on animal species, models of sepsis, organs studied, or analytical approaches should be identified and minimized by the use of appropriate experimental models resembling human sepsis, wider use of larger animal species in preclinical studies, more detailed mapping of interspecies differences and organ-specific features of oxygen utilization in addition to use of complex and standardized protocols evaluating mitochondrial respiration.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

11225. Variable expression of hypercholesterolemia in apolipoprotein E2* (Arg136 - Cys) Heterozygotes

Creator:
Jaroslav Hubáček, Jan Piťha, Petr Stávek, Schmitz, G., and Rudolf Poledne
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, sekvenování DNA, metabolismus lipidů, DNA sequencing, lipid metabolism, apolipoprotein E, rare mutation, PCR, 14, and 612
Language:
English
Description:
In the process of population screening for apo E gene polymorphism with the PCR and subsequent restriction analysis, we identified a female who demonstrated heterozygosity for an unusual restriction fragment caused by the loss of a CfoI restriction site. Sequence analysis of the apo E gene was performed and a carrier of the mutant allele with C - T substitution at cDNA position 3817 was identified, which caused an Arg136 - Cys change. The first-line relatives have been screened for this rare mutation with PCR and restriction analysis of PCR products. The complete lipoprotein parameters have been determined in the probands family. In the family, only one child had the same mutant allele as his mother had. The proband (7.49 mmol/l) with her siblings had hypercholesterolemia and a high body mass index (BMI 31.6 kg/m2). By contrast, her son had a normal lipid spectrum with normal BMI. We described the mutation apo E2* (Arg136 - Cys) in a family with elevated lipid levels, but there was no confirmation of the connection between this mutation and type III hyperlipoproteinemia or hyperlipoproteinemia at all. In the case of this mutation, other factors (mainly genetic) are important for the development of lipid metabolism disorders., J. A. Hubáček, J. Piťha, P. Stávek, G. Schmitz, R. Poledne., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

11226. Variable Lebesgue norm estimates for BMO functions

Creator:
Izuki, Mitsuo and Sawano, Yoshihiro
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
variable exponent, Morrey space, and BMO
Language:
English
Description:
In this paper, we are going to characterize the space ${\rm BMO}({\mathbb R}^n)$ through variable Lebesgue spaces and Morrey spaces. There have been many attempts to characterize the space ${\rm BMO}({\mathbb R}^n)$ by using various function spaces. For example, Ho obtained a characterization of ${\rm BMO}({\mathbb R}^n)$ with respect to rearrangement invariant spaces. However, variable Lebesgue spaces and Morrey spaces do not appear in the characterization. One of the reasons is that these spaces are not rearrangement invariant. We also obtain an analogue of the well-known John-Nirenberg inequality which can be seen as an extension to the variable Lebesgue spaces.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

11227. Variační počet, přirozený aparát fyziky

Creator:
Musilová, Jana and Musilová, Pavla
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
variační počet, variační metody, physics, calculus of variations, variational methods, matematická estetika, variační matematika, variační fyzika, 6, and 53
Language:
Czech and English
Description:
Říká se, že jedním ze znaků správné fyzikální teorie je její krása. Máme-li na mysli estetičnost matematickou, patří variační počet k matematickým metodám, které naplňují tento požadavek vrchovatě. Je také pravda, že správné (zkušeností a experimentem prověřené) fyzikální teorie bývají variační, tj. odvoditelné z variačního principu: Klasická mechanika, relativistická mechanika, kvantová mechanika, klasická elektrodynamika... Na zcela elementární úrovni předkládáme základní myšlenku a klasické postupy variačního počtu, s ukázkami použití v geometrii a fyzice. Zaměříme se pouze na variační princip prvního řádu, s důrazem na mechaniku, kde na rozdíl od teorie pole závisí řešené úlohy pouze na jedné nezávisle proměnné, ve fyzice obvykle na čase., It is said that one of the characteristic features of physical theories is their beauty. Having in mind the "mathematical aesthetic appearance" one can say that the calculus of variations highly fulfils this requirement! It is also well known that correct physical theories (those verified experimentally), are often variational, i.e. based on a variational principle: classical mechanics, relativistic mechanics, quantum mechanics, classical electrodynamics, etc. We present, at a very basic level, the fundamental ideas and classical approaches of the calculus of variations, including examples of their use in geometry and physics. We focus on the first order variational principle, emphasizing mechanics, because contrary to field theories, the variational problems in mechanics depend on one independent variable only (usually time in physics)., Jana Musilová, Pavla Musilová., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

11228. Variance-constrained H∞ finite-horizon filtering for multi-rate time-varying networked systems based on stochastic protocols

Creator:
Lyu, Ming , Zhang, Jie , and Bo, YuMing
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
H∞ finite-horizon filtering, muti-rate communication, stochastic protocol (SP), and time-varying systems
Language:
English
Description:
In this paper, the variance-constrained H∞ finite-horizon filtering problem is investigated for a class of time-varying nonlinear system under muti-rate communication network and stochastic protocol (SP). The stochastic protocol is employed to determine which sensor obtains access to the muti-rate communication network in order to relieve communication burden. A novel mapping technology is applied to characterize the randomly switching behavior of the data transmission resulting from the utilization of the SP in muti-rate communication network. By using relaxation method, sufficient conditions are derived for the existence of the finite-horizon filter satisfying both the prescribed H∞ performance and the covariance requirement of filtering errors, and the solutions of filters satisfying the above indexes are obtained by using linear matrix inequalities. Finally, the validity and effectiveness of the proposed filter scheme are verified by numerical simulation.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

11229. Variants of learning algorithm based on Kolmogorov theorem

Creator:
Neruda, Roman, Arnošt, Štědrý, and Drkošová, Jitka
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Kolmogorov networks, approximation theory, and parallel algorithms
Language:
English
Description:
A thorough analysis of theoretical and computational properties of Kolmogorov learning algorithm for feedforward neural networks lead us to proposal of efficient sequential and parallel impleinentation. A novel approach to parallelization is presented which combines our previous rcsnlts in order to achieve higher parallel speed-up.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

11230. Variational equations along integral curves of a projectable system of vector fields

Creator:
Tigăeru, Catalin
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
math, variatinal equations, and vector fields
Language:
English
Description:
There exists a rich literature on systems of connections and systems of vector fields, stimulated by the irimportance in geometry and physis. In the previous papers [T1], [T2] we examined a simple type of systems of vector fields, called parameter dependent vector fields, and established their varionational equation. In this paper we generalize the above equation to the projectable system of vector fields. The material is organized as follows: in the first section the geometry of the product bundle is presented. In the second we introduce the notion of derivative along a direction and prove Theorem 1. The third section is devoted to Theorem 2, which represents the main result of the paper. Some examples are presented in the last section. In a further paper we will apply the results in order to investigate some special systems as strong systems, “nice” systems and systems of connections generated by systems of vector fields.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

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