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1532. Cadmium is acutely toxic for murine hepatocytes: effects on intracellular free Ca2+ homeostasis
- Creator:
- Wang, S. S., Chen, L., and Xia, S. K.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Biochemie. Molekulární biologie. Biofyzika, biochemie, toxicita, kadmium, jaterní buňky, homeostáza, biochemistry, toxicity, cadmium, liver cells, homeostasis, kalciový iont, calcium ion, 2, and 577
- Language:
- English
- Description:
- We studied cadmium toxicity in murine hepatocytes in vitro. Cadmium effects on intracellular free Ca2+ concentration ([Ca2+]i) were assayed, using a laser scanning confocal microscope with a fluorescent probe, Fluo-3/AM. The results showed that administration of cadmium chloride (CdCl2, 5, 10, 25 μM) resulted in a dose-dependent decrease of hepatocyte viability and an elevated aspartate aminotransfe rase (AST) activity in the culture medium (p<0.05 for 25 μM CdCl2 vs. control). Significant increases of lactate dehydrogenase (LDH) activities in 10 and 25 μM CdCl2-exposed groups were observed (p<0.05 and p<0.01, respectively). A greatly decreased albumin content and a more malondialdehyde (MDA) formation also occurred after CdCl2 treatment. The Ca2+ concentrations in the culture medium of CdCl2-exposed hepatocytes were significantly decreased, while [Ca2+]i appeared to be significantly elevated (p<0.05 or p<0.01 vs. control). We found that in Ca2+-containing hydroxyethyl piperazine ethanesulfonic acid-buffered salt solution (HBSS) only, CdCl2 elicited [Ca2+]i increases, which comprised an initially slow ascent and a strong elevated phase. However, in Ca2+-containing HBSS with addition of 2-aminoethoxydiphenyl borane (2-APB), CdCl2 caused a mild [Ca 2+] i elevation in the absence of an initial rise phase. Removal of extracellular Ca2+ showed that CdCl2 induced an initially slow [Ca2+]i rise alone without being followed by a markedly elevated phase, but in a Ca2+-free HBSS with addition of 2-APB, CdCl2 failed to elicit the [Ca2+]i elevation. These results suggest that abnormal Ca2+ homeostasis due to cadmium may be an important mechanism of the development of the toxic effect in murine hepatocytes. [Ca2+]i elevation in acutely cadmium-exposed hepatocytes is closely related to the extracellular Ca2+ entry and an excessive release of Ca2+ from intracellular stores., S. S. Wang, L. Chen, S. K. Xia., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1533. Cadmium stress in Dongying wild soybean seedlings: growth, Cd accumulation, and photosynthesis
- Creator:
- Liu, L., Shang, Y. K., Li, L., Chen, Y. H., Qin, Z. Z., Zhou, L. J., Yuan, M., Ding, C. B., Liu, J., Huang, Y., Yang, R. W., Zhou, Y. H., and Liao, J. Q.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- pigmenty, pigments, atomic absorption spectrophotometry, Glycine soja, growth analysis, 2, and 581
- Language:
- Multiple languages
- Description:
- In order to understand better Cd resistance in soybean, Dongying wild soybean treated with different Cd concentrations were evaluated. The biomass, chlorophyll (Chl) content, leaf color, Chl a fluorescence parameters, photosynthesis parameters, and Cd contents were determined. Our results showed that when Cd concentration was ≤ 2 kg m-3, no significant decrease in biomass, photosynthetic parameters, and maximal photochemical efficiency of PSII was observed. This indicated that Dongying wild soybean resisted Cd toxic effects under such conditions. In addition, atomic absorption experiment results demonstrated that when Cd concentration was ≤ 0.5 kg m-3, the accumulation of Cd in wild soybean was lower in roots than that in shoots, while the accumulation of Cd was higher in roots than that in shoots when Cd concentration was ≥ 1 kg m-3. Therefore, Dongying wild soybean showed a certain resistance to Cd and could serve as a valuable germplasm resource for improving the breeding of Cd-resistant soybean., L. Liu, Y. K. Shang, L. Li, Y. H. Chen, Z. Z. Qin, L. J. Zhou, M. Yuan, C. B. Ding, J. Liu, Y. Huang, R. W. Yang, Y. H. Zhou, J. Q. Liao., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1534. Caemmerer, S. von: Biochemical models of leaf photosynthesis
- Creator:
- Čatský, J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- biochemical models
- Language:
- Multiple languages
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1535. Cairaella henrii gen. n., sp. n., a parasite of Norops trachyderma (Polychrotidae), and Ophiotaenia nicoleae sp. n. (Eucestoda: Proteocephalidea), a parasite of Thecadactylus rapicauda (Gekkonidae), in Ecuador
- Creator:
- Coquille, Sandrine C. and de Chambrier, Alain
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Eucestoda, Proteocephalidea, Cairaella henrii, Ophiotaenia nicoleae, new genus, new species, morphology, and Squamata
- Language:
- English
- Description:
- Cairaella henrii gen. n., sp. n. (Proteocephalidea: Proteocephalinae) is described from the intestine of Norops trachyderma (Cope) (Polychrotidae) from San Pablo de Kantesiya in Ecuador. The new genus differs from the 12 other known genera of the Proteocephalinae (and all other proteocephalidean genera) by the presence of a dense network of osmoregulatory canals situated in the cortex and by the morphology of the scolex which is flattened dorsoventrally, with elongated deeply embedded suckers possessing a well-developed circular musculature situated in the anterolateral region, and by eggs with a three-layered embryophore possessing small outgrowths on its external surface. Ophiotaenia nicoleae sp. n. is described from the intestine of Thecadactylus rapicauda (Houttuyn) (Gekkonidae) from San Pablo de Kantesiya in Ecuador. This new species is characterised by the testes arranged in two fields, numbering 142-204, the cirrus-sac length representing 21-33% of proglottis width, the genital pore situated in the middle of the proglottis or slightly anteriorly, and the ovary width representing 68-88% of proglottis width. It differs from 20 of 27 Ophiotaenia species parasitic in New World reptiles by the presence of an apical organ and from the remaining species by one to several other morphological characters, such as the number of testes, diameter and shape of the scolex, position of ventral and dorsal osmoregulatory canals, or the presence of a vaginal sphincter. Both taxa represent the first record of proteocephalidean tapeworms in polychrotid and gekkonid lizards, respectively.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1536. Calcium intake and the outcome of short-term weight management
- Creator:
- Karolína Hlavatá, Vojtěch Hainer, Milena Gojová, Petr Hlavatý, Kopský, V., Jara Nedvídková, Marie Kunešová, Jana Pařízková, Martin Wagenknecht, Miroslav Hill, and Jan Drbohlav
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, endokrinologie, obezita, vápník, hlad, endocrinology, obesity, calcium, hunger, weight change, fat-free mass, resistin, 14, and 612
- Language:
- English
- Description:
- Experimental and epidemiological studies suggest that calcium intake is inversely related to weight gain. Calcium of dairy origin has been shown to be more effective in promoting weight loss. However, clinical studies yielded controversial results concerning the role of calcium intake in weight change. The aim of this study was to ascertain whether the addition of calcium can affect the outcome of 3-week weight management (WM) with a hypocaloric diet characterized by a decreased calcium intake. Overweight/obese women (n=67; BMI 32.2±4.1 kg/m2; age 49.1±12.1 years) underwent a 4-week comprehensive WM program. WM included a 7 MJ/day diet resulting in a stable weight during the first week and a 4.5 MJ/day diet with mean daily calcium intake 350 mg during the second to fourth week. Participants were divided into three age- and BMI-matched groups who received placebo or calcium (500 mg/day). Calcium was administered either as carbonate or calcium of dairy origin (Lactoval). There was no significant difference in weight loss in response to WM between the placebo-treated and calcium-treated groups. However, addition of calcium to the diet resulted in a lower hunger score in the Eating Inventory as well as a decrease in plasma resistin levels. Body composition measured by bioimpedance demonstrated that added calcium leads to preservation of fat-free mass. Nevertheless, a greater loss of fat-free mass in the placebo group might be partly due to a greater loss of water., K. Kabrnová-Hlavatá, V. Hainer, M. Gojová, P. Hlavatý, V. Kopský, J. Nedvídková, M. Kunešová, J. Pařízková, M. Wagenknecht, M. Hill, J. Drbohlav., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1537. Calcium, carbonic anhydrase and gastric acid secretion
- Creator:
- Puscas, I., Coltau, M., Baican, M., Domuta, G., and Hecht, A.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, vápník, calcium, disodium EDTA, carbonic anhydrase, gastric acid secretion, 14, and 612
- Language:
- English
- Description:
- Previous data concerning the action of calcium (Ca) on gastric acid secretion (GAS) indicated that calcium ions increase GAS elicited by gastrin released through a vagal mechanism, and also by a direct effect on parietal cells. Our research showed that the stimulating effect of calcium on gastric acid secretion can be antagonized by verapamil administration, which reduces gastric acid secretion . In the present study we followed the effect induced by administration of calcium and Ca-chelating agents (disodium EDTA) on gastric acid secretion and on carbonic anhydrase (CA) activity. We selected two groups of healthy volunteers: Group I (n=21) received a single i.v. dose of CaCl2 (15 mg/kg b.w.), whereas Group II (n=22) received a single i.v. dose of disodium EDTA (5 mg/kg b.w.). We determined blood calcium before and after treatment, gastric acid secretion at 2 hours, erythrocyte CA II activity, and CA IV activity in membrane parietal cells, which were isolated from gastric mucosa obtained by endoscopic biopsy. Assessment of carbonic anhydrase activity was achieved by the stopped-flow method. In Group I calcium administration increased blood calcium, HCl output, CA II and CA IV activity as compared to initial values. In Group II, disodium EDTA reduced blood calcium, HCl output, CA II and CA IV activity as compared to initial values. The results demonstrated that increased blood calcium and GAS values after calcium administration correlated with the increase of erythrocyte CA II and parietal cell CA IV activity, while disodium EDTA induced a reversed process. Our results also show that cytosolic CA II and membrane CA IV values are sensitive to calcium changes and they directly depend on these levels. Our data suggest that intra- and extracellular pH changes induced by carbonic anhydrase might account for the modulation of the physiological and pathological secretory processes in the organism., I. Puscas, M. Coltau, M. Baican, G. Domuta, A. Hecht., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1538. Calcium-dependent desensitization of vanilloid receptor TRPV1: a mechanism possibly involved in analgesia induced by topical application of capsaicin
- Creator:
- Ladislav Vyklický, Karolina Nováková-Toušová, Jan Benedikt, Abdul Samad, Filip Touška, and Viktorie Vlachová
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, neurofyziologie, analgezie, neurophysiology, analgesia, vanilloid 1 receptors (TRPV1), capsaicin, topical application, desensitization, 14, and 612
- Language:
- English
- Description:
- The rationale for the topical application of capsaicin and other vanilloids in the treatment of pain is that such compounds selectively excite and subsequently desensitize nociceptive neurons. This desensitization is triggered by the activation of vanilloid receptors (TRPV1), which leads to an elevation in intracellular free Ca2+ levels. Depending on the vanilloid concentration and duration of exposure, the Ca2+ influx via TRPV1 desensitizes the channels themselves, which may represent not only a feedback mechanism protecting the cell from toxic Ca2+ overload, but also likely contributes to the analgesic effects of capsaicin. This review summarizes the current state of knowledge concerning the mechanisms that underlie the acute capsaicin-induced Ca2+-dependent desensitization of TRPV1 channels and explores to what extent they may contribute to capsaicin-induced analgesia. In view of the polymodal nature of TRPV1, we illustrate how the channels behave in their desensitized state when activated by other stimuli such as noxious heat or depolarizing voltages. We also show that the desensitized channel can be strongly reactivated by capsaicin at concentrations higher than those previously used to desensitize it. We provide a possible explanation for a high incidence of adverse effects of topical capsaicin and point to a need for more accurate clinical criteria for employing it as a reliable remedy., L. Vyklický, K. Nováková-Toušová, J. Benedikt, A. Samad, F. Touška, V. Vlachová., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1539. Calculation of natural vibration of linear undamped rotationally periodic structures
- Creator:
- Polach, Pavel
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- rotational periodicity, subsystem, natural vibration, bladed disk, and steam turbine
- Language:
- English
- Description:
- The article presents the method of the calculation of natural frequencies and mode shapes of the linear undamped rotationally periodic systems. The method is applied in the calculation of the natural vibration characteristics of the steam turbine bladed disks., Obsahuje seznam literatury, and Součástí článku je Appendix A - Solution of matrix difference equations (str. 93-97)
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1540. Calibrating electromagnetic short soil water sensors
- Creator:
- Loiskandl, Willibald, Buchan, Graeme D., Sokol, Wolfgang, Novak, Viliam, and Himmelbauer, Margarita
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- soil moisture probes, electromagnetic probes, TDR, calibration, snímače vlhkosti pôdy, elektromagnetické snímače, and kalibrácia
- Language:
- Slovak
- Description:
- The use of electromagnetic (EM) soil moisture probes is proliferating rapidly, in two broad domains: in field and laboratory research; and in strongly practical applications such as irrigation scheduling in farms or horticultural enterprises, and hydrological monitoring. Numerous commercial EM probes are available for measurement of volumetric water content (θv), spanning a range of measurement principles, and of probe dimensions and sensing volumes. However probe calibration (i.e. the relationship of actual θv to probe electrical output) can shift, often substantially, with variations in parameters such as soil texture, organic matter content, wetness range, electrical conductivity and temperature. Hence a single-valued, manufacturer-supplied calibration function is often inadequate, forcing the user to seek an application-specific calibration. The purpose of this paper is to describe systematic procedures which probe users can use to check or re-determine the calibration of their selected probe(s). Given the wide diversity of operating principles and designs of commercially-available EM probes, we illustrate these procedures with results from our own calibrations of five different short probes (length of 5 to 20 cm). Users are strongly recommended to undertake such calibration checks, which provide both a) pre-use experience, and b) more reliable in-use data. and Používanie elektromagnetických (EM) snímačov vlhkosti pôdy sa rýchlo rozširuje tak v terénnom výskume, ako aj v laboratóriu. Sú používané v praktických aplikáciách ako je riadenie závlah na farmách a záhradách, ako aj v hydrologickom monitoringu. Pre meranie vlhkosti pôdy (θv) sú dostupné početné typy komerčných EM snímačov, založených na viacerých princípoch merania a snímače majú rozdielnu veľkosť snímaných objemov pôdy. Kalibračné krivky takýchto snímačov (t.j. závislosti medzi reálnou vlhkosťou pôdy θv a elektrickým výstupom snímača) sa môžu posúvať - niekedy podstatne - a to v závislosti od rozdielnych parametrov pôdy, ako je jej textúra, obsah organických látok, rozsah vlhkostí, elektrická vodivosť a teplota. Z toho vyplýva, že jednoznačná kalibračná krivka, dodávaná výrobcom je často neadekvátna, čo núti užívateľa snímač kalibrovať v špecifických podmienkach. Cieľom tohto príspevku je opísať procedúry, ktoré môžu byť použité užívateľmi pri rekalibrácii vybraných typov snímačov. Berúc do úvahy širokú paletu princípov EM snímačov, ilustrujeme tieto procedúry výsledkami vlastných kalibračných testov na piatich typoch krátkych snímačov (dĺžka od 5 do 20 cm). Užívateľom odporúčame rekalibráciu komerčných snímačov, ktorými získajú predbežné skúsenosti a spoľahlivejšie výsledky pri meraní vlhkosti pôdy.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public