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1622. Alpha2-adrenoceptor control of ion and water transport in the newt renal distal tubule
- Creator:
- Goncharevskaya, O. A. and Monin, Yu. G.
- Type:
- article, model:article, and TEXT
- Subject:
- norepinephrine, dibenamine, propranolol, idazoxan, prazosin, distal tubule, and electrolytes
- Language:
- English
- Description:
- To study the nature of adrenergic stimulation of ions and water reabsorption in the newt renal distal tubule, stationary microperfusion of the nephron and electron probe analysis were used. After application of norepinephrine (NE 10'6 M) to the tubule surface, the fractional reabsorption of fluid increased from 15.0±3.1 to 41.30±10.4 % (n = 7, p<0.01), of Na+ from 69.30 ±6.6 to 79.10±7.5 % (p<0.05), CT from 63.30±7.6 to 72.40 ±7.9 % (p<0.05). Instead of secretion (control), there was reabsorption of K+. Fractional reabsorption of Ca2+ decreased from 51.00±6.0 to 43.00±7.0 % (p<0.05). The nonspecific alpha-adrenergic antagonist dibenamine 10"6 M completely inhibited the effect of NE while, under the action of propranolol (2xl(76 M) NE increased ion and water reabsorption significantly. When applied alone, or with NE, the specific alpha2-adrenoblocker idazoxan, 2xl0‘6 M, did not interfere with reabsorption in the distal tubule. At the same time, under the action of alphai-adrenoblocker prazosin 2xl0'6 M NE, increased the fractional reabsorption of fluid from 24.10 ±3.4 to 44.40 ±4.0 % (n = 6, p<0.001). These results serve as evidence that there exist specific alpha^adrenoceptors in the newt distal tubule the stimulation of which increases membrane permeability of the distal tubule to water, Na+, K+, Cl', but not to Ca2+.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1623. Alpínská vegetace v karech Popa Ivana
- Creator:
- Hédl, Radim and Buřivalová, Zuzana
- Type:
- article and TEXT
- Language:
- Czech
- Description:
- Lokality nad horní hranicí lesa představují z hlediska diverzity vegetace jedno z nejzajímavějších prostředí v Evropě. S různou intenzitou se kombinuje zpravidla několik faktorů prostředí, takže na poměrně malých plochách můžeme sledovat velkou pestrost vegetačních typů. To platí především pro kary, ledovcem modelovaná údolí, kde existují příkré gradienty klimatických a substrátových podmínek. Článek přibližuje metody a výsledky studia těchto jevů na hoře Pop Ivan v Ukrajinských Karpatech. and Localities above the timberline are some of the most interesting environments in Europe in terms of vegetation diversity. Several environmental factors combine here to different degrees of intensity, which results in a great diversity of vegetation types on a relatively small area. This phenomenon is typical mainly for glacial cirques – valleys shaped by glaciers – where sharp gradients of climatic and substrate conditions exist. The article deals with the methods and results of the study of such phenomena in the Ukrainian Carpathians.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/
1624. Alteration of components of chlorophyll-protein complexes and distribution of excitation energy between the two photosystems in two new rice chlorophyll b-less mutants
- Creator:
- Lin, Zhi-Fang, Peng, Chang-Lian, Lin, Gui-Zhu, and Zhang, Jing-Liu
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, chlorophyll-protein complexes, Mg2+, photosystems 1 and 2, and Oryza
- Language:
- Multiple languages
- Description:
- Two new yellow rice chlorophyll (Chl) b-less (lack) mutants VG28-1 and VG30-5 differ from the other known Chl b-less mutants with larger amounts of soluble protein and ribulose-1,5-bisphosphate carboxylase/oxygenase small sub-unit and smaller amounts of Chl a. We investigated the altered features of Chl-protein complexes and excitation energy distribution in these two mutants, as compared with wild type (WT) rice cv. Zhonghua 11 by using native mild green gel electrophoresis and SDS-PAGE, and 77 K Chl fluorescence in the presence of Mg2+. WT rice revealed five pigment-protein bands and fourteen polypeptides in thylakoid membranes. Two Chl b-less mutants showed only CPI and CPa pigment bands, and contained no 25 and 26 kDa polypeptides, reduced amounts of the 21 kDa polypeptide, but increased quantities of 32, 33, 56, 66, and 19 kDa polypeptides. The enhanced absorption of CPI and CPa and the higher Chl fluorescence emission ratio of F685/F720 were also observed in these mutants. This suggested that the reduction or loss of the antenna LHC1 and LHC2 was compensated by an increment in core component and the capacity to harvest photon energy of photosystem (PS) 1 and PS2, as well as in the fraction of excitation energy distributed to PS2 in the two mutants. 77 K Chl fluorescence spectra of thylakoid membranes showed that the PS1 fluorescence emission was shifted from 730 nm in WT rice to 720 nm in the mutants. The regulation of Mg2+ to excitation energy distribution between the two photosystems was complicated. 10 mM Mg2+ did not affect noticeably the F685/F730 emission ratio of WT thylakoid membranes, but increased the ratio of F685/F720 in the two mutants due to a reduced emission at 685 nm as compared to that at 720 nm. and Zhu-Fang Lin ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1625. Alterations in Calcium Homeostasis as Biological Marker for Mild Alzheimer´s Disease?
- Creator:
- Řípová, D., Platilová, V., Strunecká, A., Jirák, |R., and Höschl, C.
- Type:
- article, model:article, and TEXT
- Subject:
- Alzheimer's disease, Vascular dementia, Platelets, Calcium homeostasis, and Biological marker
- Language:
- English
- Description:
- The calcium hypothesis of neurodegenerative disorders such as Alzheimer´s disease (AD) suggests that altered cytosolic Ca2+ levels ([Ca2+]i) and/or disturbances in Ca2+ homeostasis concern cellular mechanisms underlying neuronal pathology. To search for a diagnostic marker of Alzheimer´s disease, we measured cytosolic calcium concentrations in platelets of AD patients, age-matched control subjects (AMC), and vascular dementia (VD) patients. The ([Ca2+]i) was determined using long wavelength indicator Fluo-3AM in 21 mild AD patients, 17 AMC, and 23 patients with VD. The basal values of [Ca2+]i were significantly lower in AD compared to AMC. After the addition of 1 mM calcium, the [Ca2+]i markedly increased in platelets of AD compared to AMC and VD. Measurement of calcium homeostasis could provide a very sensitive, but less specific biological marker of AD. These results support the hypothesis that influencing calcium homeostasis may provide a therapeutic strategy in dementia.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1626. Alterations in electron transport characteristics during senescence of Cucumis cotyledonary leaves. Analysis of the effects of inhibitors
- Creator:
- Prakash, J. S. S., Baig, M. A., and Mohanty, Prasanna
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- atrazine, cucumber, DCMU, dibromothymoquinone, KCN, photosystems 1 and 2, plant age, and thylakoid proteins
- Language:
- Multiple languages
- Description:
- Cotyledonary leaves of Cucumis sativus cv. Poinsette exhibited senescence-induced losses in chlorophyll (Chl) and protein contents within three weeks since germination. Chl and protein concentrations in cotyledonary leaves approached maximum on 6th d after germination and they declined to 50 and 41 %, respectively, by the 20th day of growth. Activities of both photosystem (PS) 2 and PS1 decreased by 33 and 31 %, respectively, on the 20th day, compared to the control 6th day. Changes in sensitivity of PS2 to inhibitors like atrazine and dibromothymoquinone and sensitivity of PS1 to KCN accompanied the changes in PS2 and PS1 activities. Hence both the acceptor side of PS2 and the donor side of PS1 are affected by senescence-induced changes in cucumber cotyledonary leaves. and J. S. S. Prakash, M. A. Baig, Prasanna Mohanty.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1627. Alterations in Hippocampal Antioxidant Enzyme Activities and Sympatho-Adrenomedullary System of Rats in Response to Different Stress Models
- Creator:
- Pajović, S.B., Pejić, S., Stojiljković, V., Gavrilović, Lj. , Dronjak, S., and Kanazir , D.T.
- Type:
- article, model:article, and TEXT
- Subject:
- Stress, Hippocampus, Antioxidant enzymes, and Catecholamines
- Language:
- English
- Description:
- The study deals with activity of three antioxidant enzymes, copper, zinc-superoxide dismutase (CuZnSOD), manganese superoxide dismutase (MnSOD), catalase (CAT) in hippocampus of rats, following the exposure to single chronic (individual housing or forced swimming) and acute (immobilization or cold) stress, as well as to combined chronic/acute stress. In addition, plasma noradrenaline (NA) and adrenaline (A) concentrations were measured in the same stress conditions, because their autooxidation can add to the oxidative stress. We observed that i) long-term social isolation and repeated forced swimming had minor effects on plasma catecholamines, but in the long-term pretreated groups, acute stressors caused profound elevation NA and A levels, ii) chronic stressors activate antioxidant enzymes, iii) acute stressors decrease catalase activity, their effects on CuZnSOD appear to be stressor-dependent, whereas MnSOD is not affected by acute stressors, and iv) pre-exposure to chronic stress affects the antioxidant-related effects of acute stressors, but this effect depends to a large extent on the type of the chronic stressor. Based on both metabolic and neuroendocrine data, long-term isolation appears to be a robust psychological stressor and to induce a “priming” effect specifically on the CuZnSOD and CAT activity.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1628. Alterations in photosynthesis and antioxidant enzyme activity in winter wheat subjected to post-anthesis water-logging
- Creator:
- Tan, W., Liu, J., Dai, T., Jing, Q., Cao, W., and Jiang, D.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- catalase, chlorophyll fluorescence; ;, dry matter redistribution, net photosynthetic rate, peroxidase, photosystem 2, superoxide dismutase, Triticum aestivum, and yield
- Language:
- Multiple languages
- Description:
- Winter wheat (Triticum aestivum L.) cultivars Yangmai 9 (water-logging tolerant) and Yumai 34 (water-logging sensitive) were subjected to water-logging (WL) from 7 d after anthesis to determine the responses of photosynthesis and anti-oxidative enzyme activities in flag leaf. At 15 d after treatment (DAT), net photosynthetic rate under WL was only 3.7 and 8.9 µmol(CO2) m-2 s-1 in Yumai 34 and Yangmai 9, respectively, which was much lower than in the control. Ratios of variable to maximum and variable to initial fluorescence, actual photosynthetic efficiency, and photochemical quenching were much lower, while initial fluorescence and non-photochemical quenching were much higher under WL than in control, indicating damage to photosystem 2. WL decreased activities of superoxide dismutase and catalase in both cultivars, and activity of peroxidase (POD) in Yumai 34, while POD activity in Yangmai 9 was mostly increased. The obvious decrease in the amount of post-anthesis accumulated dry matter, which was redistributed to grains, also contributed to the grain yield loss under WL. and W. Tan ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1629. Alterations in the baroreceptor-heart rate reflex in conscious inbred polydipsic (STR/N) mice
- Creator:
- Chu, C. P., Cui, B. R., Kannan, H., and Qiu, D. L.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, phenylephrine, sodium nitroprusside, baroreceptor reflex, inbred polydipsic mice, 14, and 612
- Language:
- English
- Description:
- STR/N is an inbred strain of mice which is known to exhibit extreme polydipsia and polyuria. We previously found central administration of angiotensin II enhanced cardiovascular responses in STR/N mice than normal mice, suggesting that STR/N mice might exhibit different cardiovascular responses. Therefore, in this study, we investigated daily mean arterial blood pressure and heart rate, and changes in the baroreceptor-heart rate reflex in conscious STR/N mice and control (ICR) mice. We found that variability in daily mean arterial blood pressure and heart rate was significantly larger in STR/N mice than in ICR mice (p<0.05). There was a stronger response to phenylephrine (PE) in STR/N mice than in ICR mice. For baroreceptor reflex sensitivity, in the rapid response period, the slopes of PE and sodium nitroprusside (SNP) were more negative in STR/N mice than in ICR mice. In the later period, the slopes of PE and SNP were negatively correlated between heart rate and blood pressure in ICR mice, but their slopes were positively correlated in STR/N mice. These results indicated that STR/N mice exhibited the different cardiovascular responses than ICR mice, suggesting that the dysfunction of baroreceptor reflex happened in conscious STR/N mice., C. P. Chu, B. R. Cui, H. Kannan, D. L. Qiu., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1630. Alterations in the expression of the apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE/ref-1) and DNA damage in the caudal region of acute and chronic spinal cord injured rats treated by embryonic neural stem cells
- Creator:
- Dagci, T., Armagan, G., Konyalioglu, S., and Yalcin, A.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, poranění míchy, spinal cord injuries, stem cell transplantation, DNA damage, APE protein, ref-1 protein, 14, and 612
- Language:
- English
- Description:
- The oxidative mechanisms of injury-induced damage of neurons within the spinal cord are not very well understood. We used a model of T8-T9 spinal cord injury (SCI) in the rat to induce neuronal degeneration. In this spinal cord injury model, unilateral avulsion of the spinal cord causes oxidative stress of neurons. We tested the hypothesis that apurinic/apyrimidinic endonuclease (or redox effector factor-1, APE/Ref-1) regulates this neuronal oxidation mechanism in the spinal cord region caudal to the lesion, and that DNA damage is an early upstream signal. The embryonic neural stem cell therapy significantly decreased DNA- damage levels in both study groups - acutely (followed up to 7 days after SCI), and chronically (followed up to 28 days after SCI) injured animals. Meanwhile, mRNA levels of APE/Ref-1 significantly increased after embryonic neural stem cell therapy in acutely and chronically injured an imals when compared to acute and chronic sham groups. Our da ta has demonstrated that an increase of APE/Ref-1 mRNA levels in the caudal region of spinal cord strongly correlated with DNA damage after traumatic spinal cord injury. We suggest that DNA damage can be observed both in lesional and caudal regions of the acutely and chronically injured groups, but DNA damage is reduced with embryonic neural stem cell therapy., T. Dagci, G. Armagan, S. Konyalioglu, A. Yalcin., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public