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274742. Effects of static magnetic field and pulsed electromagnetic field on viability of human chondrocytes in vitro
- Creator:
- Štolfa, Š., Škorvánek, M., Štolfa, P., Rosocha, J., Vaško, G., and Ján Sabo
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, chondrocyty, magnetické pole, chondrocytes, magnetic fields, osteoarthritis, 14, and 612
- Language:
- English
- Description:
- Effects of electromagnetic fields (EMFs) on human cell lines were described in numerous studies, but still many questions remain unanswered. Our experiment was designed with the aim of studying the effects of EMFs on the metabolic activity of chondrocytes in vitro. Human chondrocyte in vitro cultures, cultured in medium supplemented with 20 % fetal calf serum, were exposed to static magnetic field (SMF) (intensity of 0.6 T) and pulsed electromagnetic fields (PEMF) (21.2 MHz period of 15 ms, burst duration of 2 ms, amplification 3 dBm (0.1 V) and maximum output of 250 W) continually for 72 h. After the exposure, viability was determined using the MTT test and compared with a nonexposed control culture. As compared to the control sample the exposure to SMF resulted in a statistically significant increase (p<0.001) in viability. However, the increase of viability after PEMF exposure was not significant. This could be due to the frequency dependent effect on human cells. The experiments demonstrated that magnetic fields, using the above parameters, have a positive effect on the viability of human chondrocytes cultured in vitro., Š. Štolfa, M. Škorvánek, P. Štolfa, J. Rosocha, G. Vaško, J. Sabo., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
274743. Effects of strength weakening and interface slipping on rock mass with different dip angle structure planes
- Creator:
- Wang, Pu, Jiang, Lishuai , Li, Xiaoyu , Zheng, Pengqiang , and Qin, Guangpeng
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- structure plane, different dip angle, strength weakening effect, interface slipping effect, and rock burst
- Language:
- English
- Description:
- Micro-mechanical behaviors of rock masses with structure planes can provide information regarding precursory characteristics of macro-fracture of strata and rock bursts. Hence, numerical simulation with uniaxial compression test is conducted using Realistic Failure Process Analysis (RFPA). Then, mechanical properties and progressive failure processes for rock masses with different dip angle structure planes are studied, and the macroscopic fractures, mechanical responses, and acoustic emission (AE) responses of rock masses are analyzed. Moreover, the strength weakening and interface slipping effects with different dip angle structure planes are revealed. The results show that rocks with different dip angle structure planes show significant strength and interface slipping effects. A small dip angle structure plane has little influence on the rock strength and interface slipping, which mainly manifests as failure in rock interiors. For medium dip angle structure plane, the rock strength decreases obviously, and interface slipping is notable along the structure plane. The effects caused by the weak plane are more prominent with rising dip angles. Compared to rocks with small dip angle structure planes, those with medium dip angle structure planes are more easily broken. However, the total energy released and total AE counts are smaller, indicating less serious bursting liability from rock failure.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
274744. Effects of structural heterogeneity of a laboratory arena on the movement patterns of adult Eriopis connexa and Hippodamia variegata (Coleoptera: Coccinellidae)
- Creator:
- Grez, Audrey A. and Villagrán, Paula
- Type:
- article, model:article, and TEXT
- Subject:
- movement behaviour, coccinellids, Eriopis connexa, Hippodamia variegata, structural heterogeneity, and laboratory arena
- Language:
- English
- Description:
- We asked if the structural heterogeneity of a laboratory arena differentially affected the abandonment of the plot, residence time, locomotory rate, pause duration and turning rate of adult Eriopis connexa and Hippodamia variegata (Coleoptera: Coccinellidae). We simulated an increase in heterogeneity by distributing vertically-oriented toothpicks in a circular arena: one control (without toothpicks), one uniform plot (toothpicks every 1 cm) and one random plot (randomly distributed toothpicks). No food was provided inside the arena. Coccinellids were released individually in the centre of each plot and their movement was videotaped. Fewer H. variegata adults left the plots as these become more heterogeneous. E. connexa did not discriminate between plots in their residence time, but H. variegata remained longer in the uniform and longest in the random plots. H. variegata only stayed longer than E. connexa in the random plots. This resulted because adults of H. variegata were stationary for longer periods, moved more slowly and less linearly and explored a higher number of toothpicks than adults of E. connexa in more heterogeneous environments. Thus, the physical structure of the environment differentially affects the movement patterns of insects. Eriopis connexa seems to be less sensitive to structural heterogeneity than H. variegata.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
274745. Effects of substrate composition and water temperature on the emergence success of lacustrine brown trout Salmo trutta m. lacustris L. fry from natural redds
- Creator:
- Radtke, Grzegorz
- Type:
- article, model:article, and TEXT
- Subject:
- spawning, redds, fry traps, survival, Salmo trutta, and the Trzebiocha stream
- Language:
- English
- Description:
- The emergence of lake-migratory brown trout Salmo trutta m. lacustris L. fry from natural redds was observed in a small lake outlet stream. A total of 1104 emerging fry were captured in traps in nine of the 12 investigated redds during three seasons. In 2005, all the fry emerged during the daytime, but in 2007 and 2009 they emerged mostly at night. Furthermore, the timing of emergence was earlier than expected from temperature models. The fry left the redds at a water temperature range of 6.2-15.0 °C, and the emergence pattern was correlated with the moon phase. The number of fry captured was strongly affected by the percentage of fine particles < 1 mm and the 8-16 mm particle content, and was positively correlated with the geometric mean of substrate particle size (Dg) and the index of permeability: the fredle index (fi). The estimated survival rate between egg deposition and fry emergence ranged from 0.0 to 59.8 % in individual redds. Additionally, the greatest number of fry and the highest survival rate were observed in redds that had the high water velocity and shortest duration of intragravel period.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
274746. Effects of supplementary potassium nitrate on growth and gas-exchange characteristics of salt-stressed citrus seedlings
- Creator:
- Khoshbakht, D., Ghorbani, A., Baninasab, B., Naseri, L. A., and Mirzaei, M.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, dusík, citrusy, photosynthesis, nitrogen, citruses, chlorophyll fluorescence, mineral nutrition, net gas exchange, rootstocks, salinity, salt stress, potassium nitrate, 2, and 581
- Language:
- Multiple languages
- Description:
- We investigated the effects of supplementary KNO3 and NaCl on one-year-old, potted Valencia orange (Citrus sinensis) scions grafted on Iranian mandarin Bakraii [Citrus reticulate × Citrus limetta] (Valencia/Bakraii) and Carrizo citrange [C. sinensis × Poncirus trifoliata] (Valencia/Carrizo) rootstocks. After watering plants for 60 days with 50 mM NaCl, the lowest reduction in dry mass, stomatal conductance, and chlorophyll (Chl) content was found in Valencia/Bakraii. Bakraii accumulated more Cl- and Na+ in roots and transferred less to Valencia leaves compared with Carrizo rootstock. Moreover, higher net photosynthetic rate was found in Valencia/Bakraii than those on Carrizo rootstock. NaCl caused a decrease in the maximal efficiency of PSII photochemistry (Fv/Fm) and effective quantum yield (ΦPSII) but elevated coefficient of nonphotochemical quenching. Salinity reduced Ca2+, Mg2+, and total N contents, and increased Na+/K+ ratio in leaves and roots of both grafting combinations. Salinity increased K+ and proline content in leaves and decreased K+ concentrations in roots of both grafting combinations. In salinized plants, nitrate supplementation (10 mM KNO3) reduced leaf abscission, Cl-, Na+, Na+/K+, and Ca2+ concentrations in leaves and roots of both combinations. K+ and N concentrations and proline increased in leaves of the nitrate-supplemented salinized plants. Supplementary nitrate increased leaf number and area, stem elongation, Chl content, Fv/Fm, and ΦPSII and stimulated photosynthetic activity. Thus, nitrate ameliorated the deleterious effects of NaCl stress and stimulated the plant metabolism and growth. It can be used as a vital treatment under such condition., D. Khoshbakht, A. Ghorbani, B. Baninasab, L. A. Naseri, M. Mirzaei., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
274747. Effects of temperature and genetic stress on life history and fluctuating wing asymmetry in Culex pipiens mosquitoes
- Creator:
- Mpho, Mandla, Callaghan, Amanda, and Holloway, J.
- Type:
- article, model:article, and TEXT
- Subject:
- Fluctuating asymmetry, inbreeding, organophosphate resistance, environmental stress, Culex pipiens, and biomonitor
- Language:
- English
- Description:
- Fluctuating asymmetry (FA) of bilaterally symmetrical organisms has been introduced as a promising indicator of environmental stress. Stress factors reported to contribute to developmental stability include inbreeding and the presence of resistance genes. In the current study we examined the effect of stress derived from high developmental temperatures, resistance genes and low genetic variation on life history variables and wing FA in Culex pipiens mosquitoes. Three strains were compared: two inbred laboratory strains sharing a similar genetic background but differing in that one strain contained organophosphate (OP) resistance genes, and a third strain that was an outbred OP resistant field strain recently collected from India. There were no strong and general trends that suggested that the OP resistant lab strain was less fit than the OP susceptible strain, although there were some specific among strain differences for some treatments. Fluctuating asymmetry (FA) of wing traits was higher in the laboratory strains than the field strain, suggesting that inbreeding may cause elevated FA in the study species. There was no evidence that the resistance genes were associated with increased wing FA. Wing FA increased with increasing developmental temperature in females, but the association was less strong in males. There was a significant difference between the sexes in this respect. The results are discussed with reference to the value of FA as a biomonitor of environmental stress.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
274748. Effects of temperature and irradiance on quantum yield of PSII photochemistry and xanthophyll cycle in a tropical and a temperate species
- Creator:
- Dongsansuk, A., Lütz, Cornelius, and Neuner, G.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, Allium ursinum, β-carotene, freezing stress, heat, ice nucleation, lutein, Musa sp., photosynthetic pigments, 2, and 58
- Language:
- Multiple languages
- Description:
- a1_The effect of a wide range of temperatures (-15 and 60°C) in darkness or under strong irradiation [1,600 μmol(photon) m-2 s-1] on quantum yield of photosystem II photochemistry and xanthophyll cycle pigments was investigated in a tropical fruit crop (Musa sp.) and a temperate spring flowering plant (Allium ursinum L.). In darkness within the nonlethal thermal window of A. ursinum (from -6.7 to 47.7°C; 54.5 K) and of Musa sp. (from -2.2°C to 49.5°C; 51.7 K) maximal quantum yield of PSII photochemistry (Fv/Fm) was fairly unaffected by temperature over more than 40 K. At low temperature Fv/Fm started to drop with ice nucleation but significantly only with initial frost injuries (temperature at 10% frost damage; LT10). The critical high temperature threshold for PSII (Tc) was 43.8°C in A. ursinum and 44.7°C in Musa sp. Under strong irradiation, exposure to temperatures exceeding the growth ones but being still nonlethal caused photoinhibition in both species. Severity of photoinhibition increased with increasing distance to the growth temperature range. ΔF/Fm′ revealed distinctly different optimum temperature ranges: 27-36°C for Musa sp. and 18-27°C for A. ursinum exceeding maximum growth temperature by 2-7 K. In both species only at temperatures > 30°C zeaxanthin increased and violaxanthin decreased significantly. At nonlethal low temperature relative amounts of xanthophylls remained unchanged. At temperatures > 40°C β-carotene increased significantly in both species. In Musa sp. lutein and neoxanthin were significantly increased at 45°C, in A. ursinum lutein remained unchanged, neoxanthin levels decreased in the supraoptimal temperature range. In darkness, Fv/Fm was highly temperature-insensitive in both species., a2_Under strong irradiation, whenever growth temperature was exceeded, photoinhibition occurred with xanthophylls being changed only under supraoptimal temperature conditions as an antiradical defence mechanism., A. Dongsansuk, C. Lütz, and G. Neuner., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
274749. Effects of temperature and neuroactive substances on hypothalamic neurones in vitro: possible implications for the induction of fever
- Creator:
- Hori, T., Kiyohara, T., Nakashima, T., Mizuno, K., Muratani, H., and Katafuchi, T.
- Type:
- article, model:article, and TEXT
- Subject:
- thermosensitivity, interleukin-1, interferon, αMSH, and prostaglandin E2
- Language:
- English
- Description:
- This paper reviews some of our findings which have shown the usefulness of in vitro methods in the study of hypothalamic neurones. (1) Membrane current analyses of dispersed neurones of the rat preoptic and anterior hypothalamus (POA) during thermal stimulation have revealed that warm-sensitive neurones are endowed with a non-inactivating Na+ channel having a high Qjo in the hyperthermic range (35-41 °C). (2) A brain slice study has shown that neurones in the organum vasculosum lamina terminalis (OVLT) region have much higher sensitivity to PGE2 than POA neurones. This provides further evidence of a critical role of the OVLT in translation of blood-borne cytokine signals into brain signals for fever induction. (3) Local application of IL -1/9 and IFNa altered the activity of thermosensitive (TS) neurones and glucose responsive (GR) neurones in vitro in an appropriate way to produce fever and anorexia. While the responses to IL -1/9 required the local release of prostaglandins, the responses to IFNa were found to be mediated by opioid receptor mechanisms. (4) The responses of POA TS neurones and VMH GR neurones to IL -1/9 but not those to IFNa, were reversibly blocked by aMSII, an endogenous antipyretic peptide. Thus, immune cytokines and their related neuroactive substances may affect hypothalamic TS and GR neurones thereby producing elaborately regulated changes in homeostatic functions such as thermoregulation (fever) and feeding (anorexia), which are considered as host defence responses.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
274750. Effects of temperature and nitrogen application on photosynthetic characteristics and the absorption and distribution of carbon and nitrogen in apple plants
- Creator:
- Zhang, H.H., Liu, H.F., Li, Z., Ding, H.F., Xue, Z.X., Zhao, F.Y., Yu, S.L., and Yu, K.
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, gas exchange, Malus sieversii, temperature stress, and tracing technology
- Language:
- Multiple languages
- Description:
- Low temperature has negative effects on apple photosynthesis by inhibiting the accumulations of photosynthates and nitrogen. The interactive effects of low temperature and nitrogen application on photosynthetic parameters and the absorption and distribution of carbon and nitrogen in different organs were assessed to investigate if nitrogen application can relieve the low-temperature stress on gas exchange and the accumulations of carbon and nitrogen inside the apple plants. No matter under normal or low-temperature conditions, nitrogen application both improved the photosynthetic parameters including net photosynthetic rate, intercellular CO2 concentration, and quantum yield of regulated energy dissipation of PSII as well as the absorption of carbon and nitrogen in roots, stems, and leaves. Thus, we conclude that nitrogen application can relieve the effects of low-temperature stress on photosynthesis and is of benefit for the accumulations of carbon and nitrogen in multiple organs of apple seedlings.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public