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10802. 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
10803. 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
10804. Variace na Korán: Islám v diaspoře
- Creator:
- Bielický, Viktor
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Czech
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
10805. 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
10806. Variation in carbonic anhydrase activity and its relationship with photosynthesis and dry mass of mustard
- Creator:
- Khan, N.A.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Carbonic anhydrase (CA) activity and net photosynthetic rate (/’N) in the leaves, and plant dry mass (DM) in twelve cultivars of mustard (Brassica juncea L.) were measured 50, 70 and 90 d after sowing. At different sampling stages CA was strongly associated with PN and DM.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
10807. Variation in parameters affecting risk of human disease due to TBE virus
- Creator:
- Korenberg, E. I. and Kovalevskii, Yu V.
- Format:
- Type:
- model:internalpart and TEXT
- Subject:
- tick-borne encephalitis, Ixodes persulcatus, and risk of infection
- Language:
- English
- Description:
- To rank variables affecting risk of human disease due to tick-borne encephalitis (TBE) virus in the Russian Far East, we compared annual changes in ( 1 ) frequency of human contact with vector ticks, (2) prevalence of infection in the tick population and (3) quantity of virus present infected ticks. Sites were sampled uniformly over a 4-year period in a forested region where Ixodes persulcatus serves as the principle vector. The questing density of ticks on vegetation remained relatively constant during the course of this study. The frequency of contacts of the local human population with ticks carrying different doses of the TBE virus was changeable. The rate of TBE infection of humans in the study site corresponded to that of human contacts with highly infected ticks. The density of highly infected ticks represents the principal parameter for determining potential epidemiological significance of a natural TBE focus.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
10808. Variation of photosynthetic characteristics and yield in wild and cultivated species of yams (Dioscorea spp.) from Koraput, India
- Creator:
- Padhan, B. and Panda, D.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, chlorophyll fluorescence, gas exchange, tuber yield, 2, and 581
- Language:
- Multiple languages
- Description:
- Variations in leaf gas-exchange characteristics, PSII activity, leaf pigments, and tuber yield were investigated in seven wild and one cultivated species of Dioscorea from Koraput, India, in order to find out their overall adaptability to the environment. The leaf photosynthetic rate, transpiration, stomatal conductance, water-use efficiency, carboxylation efficiency, and photosynthetic pigments were significantly higher in some wild species compared to the cultivated species. In addition, some wild species showed better photochemical efficiency of PSII, photochemical quenching, and electron transport rate in comparison to cultivated one. Furthermore, leaf dry matter accumulation and tuber yield was also higher in some wild species compared to the cultivated species. Taken together, the wild species, such as D. oppositifolia, D. hamiltonii, and D. pubera, showed the superior photosynthetic efficiency compared to the cultivated D. alata and they could be used for future crop improvement programs., B. Padhan, D. Panda., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
10809. Variation of thorax flight temperature among twenty Australian butterflies (Lepidoptera: Papilionidae, Nymphalidae, Pieridae, Hesperiidae, Lycaenidae)
- Creator:
- Nève, Gabriel and Hall, Casey
- Format:
- print, počítač, and online zdroj
- Type:
- article, články, journal articles, model:article, and TEXT
- Subject:
- Zoologie, otakárkovití, babočkovití, běláskovití, motýli, Papilionidae, Nymphalidae, Pieridae, butterflies, Lepidoptera, Hesperiidae, Lycaenidae, thorax flight temperature, wing loading, infra red thermometer, warming-up rate, physical constraint, allometry, 2, and 59
- Language:
- English
- Description:
- Thermal requirements for flight in butterflies is determined by a combination of external factors, behaviour and physical constraints. Thorax temperature of 152 butterflies was monitored with an infra-red thermometer in controlled laboratory conditions. The temperature at take-off varied from 13.4°C, for a female Heteronympha merope to 46.3°C, for a female Junonia villida. Heteronympha merope, an understorey species, had the lowest recorded take-off temperatures, with females flying at a much lower thorax temperatures than males. Among the tested butterfly species, warming-up rate was positively correlated with take-off temperature and negatively with body mass. Wing loading is a major variable in determining the thorax flight temperature. Butterflies with the highest wing-loadings experienced the highest thorax temperatures at take-off. A notable exception to this rule is Trapezites symmomus, the only Hesperiidae of our data set, which had thorax flight temperatures of 31.5°C and 34.5°C, well within the range of the observed butterflies, despite a wing load ca. five times higher. The high thorax temperature recorded in J. villida is probably linked to its high flight speed. The results highlight the importance of physical constraints such as body size on the thermal requirements for flight across a range of butterfly species., Gabriel Nève, Casey Hall., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
10810. Variations in light energy dissipation in Woodfordia fruticosa leaves during expansion
- Creator:
- Zhang, S.-B. and Zhang, J.-L.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- anthocyanin, leaf expansion, nonphotochemical quenching, gas exchange, photosynthetic electron flow, photorespiration, 2, and 581
- Language:
- Multiple languages
- Description:
- Young leaves of tropical trees frequently appear red in color, with the redness disappearing as the leaves mature. During leaf expansion, plants may employ photoprotective mechanisms to cope with high light intensities; however, the variations in anthocyanin contents, nonphotochemical quenching (NPQ), and photorespiration during leaf expansion are poorly understood. Here, we investigated pigment contents, gas exchange, and chlorophyll (Chl) fluorescence in Woodfordia fruticosa leaves during their expansion. Young red leaves had significantly lower Chl content than that of expanding or mature leaves, but they accumulated significantly higher anthocyanins and dissipated more excited light energy through NPQ. As the leaves matured, net photosynthetic rate, total electron flow through PSII, and electron flow for ribulose-1,5-bisphosphate oxygenation gradually increased. Our results provided evidence that photorespiration is of fundamental importance in regulating the photosynthetic electron flow and CO2 assimilation during leaf expansion., S.-B. Zhang, J.-L. Zhang., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public