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1962. 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
1963. Alpine bullhead (Cottus poecilopus Heckel): a potential refuge for Gyrodactylus salaris Malmberg, 1957 (Monogenea)
- Creator:
- Bakke, Tor A., Paterson, Rachel A. , and Cable, Jo
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- Gyrodactylidae, Siberian bullhead, Atlantic salmon, reservoir host, experimental infection, and Norway
- Language:
- English
- Description:
- The notifiable freshwater pathogen Gyrodactylus salaris Malmberg, 1957 tends to be a generalist in contrast to other monogeneans. Whilst it causes most damage to its primary host, the Atlantic salmon (Salmo salar Linnaeus), transport and reservoir hosts likely play a key role in maintaining the parasite in the environment. Here, we tested the ability of G. salaris (strain River Lierelva, southern Norway) to infect and reproduce on a population of wild caught alpine bullhead (Cottus poecilopus Heckel). Exposure of alpine bullhead yearlings (0+) to G. salaris for 24 h at low (6.5 °C) or high temperature (11.5 °C) resulted in the establishment of 1 to 104 parasites per fish. Eight to nine days post-infection at high temperature, the infection of G. salaris was eliminated, indicative of innate host immunity. In contrast, at low temperature G. salaris infections persisted for 47-48 days. The relative lengthy infection of alpine bullhead with G. salaris compared to other non-salmonids tested may be due to low temperature and high initial infection load in combination with an epibiont infection. The present results suggest that this non-salmonid may function as a temperature-dependent transport or reservoir host for G. salaris.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1964. Alpine wetlands in the West Carpathians: vegetation survey and vegetation-environment relationships
- Creator:
- Sekulová, Lucie, Hájek, Michal, Hájková, Petra, Mikulášková, Eva, and Rozbrojová, Zuzana
- Type:
- article and TEXT
- Subject:
- azonal habitats, bogs, environmental gradients, fens, species richness, springs, and water chemistry
- Language:
- English
- Description:
- Wetland vegetation in the sub(alpine) zone of the West Carpathians (Poland, Slovakia) was studied with particular reference to the following questions: (i) What are the main types of (sub)alpine fen, bog and spring vegetation above the timberline in the West Carpathians? (ii) Which major environmental gradients are associated with the variation in floristic composition? (iii) What determines the α-diversity of bryophytes and vascular plants in the different vegetation types? Vegetation plots were sampled and direct measurements of certain environmental characteristics recorded. Cluster analysis was used to distinguish the vegetation types, DCA and CCA to reveal the main vegetation gradients and environmental factors, and general regression models to identify the factors determining the α-diversity. Classification at the level of 12 clusters was ecologically and syntaxonomically interpretable. Two associations not mentioned in the most recent vegetation survey of Slovakia were distinguished and the syntaxonomical positions of others revised. The synthesis of collected and published vegetation data for the two countries has modified the classification concept of (sub)alpine wetlands in the West Carpathians. Whereas pH predominantly determined floristic differences among classes, different factors governed the species composition within classes. While the diversity of the vegetation of springs (Montio-Cardaminetea) was mostly determined by water chemistry, altitude and geomorphology appeared to be more important within fens and bogs. The species richness of spring vegetation was more influenced by mineral richness than water pH and for bryophyte richness the slope inclination was also important. The species richness of fens and bogs increased with pH. It is concluded that the ecological gradients influencing the floristic composition and species richness of (sub)alpine wetlands are strongly habitat-dependent.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/
1965. Alster, Bendt. Wisdom of Ancient Sumer
- Creator:
- Hruška, Blahoslav
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Language:
- English
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1966. Alteration of sex-related developmental modules: A case of "feminized" male wing morphology in Creobroter gemmatus (Mantodea: Hymenopodidae)
- Creator:
- Béthoux, Olivier
- Type:
- article, model:article, and TEXT
- Subject:
- Homology, modular organization, mixed gynandromorphism, feminization, evolution, and Hymenopodidae
- Language:
- English
- Description:
- A particular case of the alteration of the organization of a developmental module is presented, viz. mixed gynandromorphism in Creobroter gemmatus, in which a male exhibits the usual fore- and hind wing venation and shape of its sex, but patterns of coloration typical of females. Homologies between corresponding areas of the fore- and hind wings are suggested. "Feminization" is defined as the occurrence of traits typical of the female phenotype in a male, and is suggested as a plausible way in which insect wing morphology may be transformed.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1967. 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
1968. Alterations in endothelin receptors following hemorrhage and resuscitation by centhaquin
- Creator:
- Briyal, S., Gandhakwala, R., Gulati, A., Lavhale, M. S., and Khan, M.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fyziologie člověka, human physiology, Hemorrhagic shock, Centhaquin, Resuscitation, Endothelin, Cytokines, 14, and 612
- Language:
- English
- Description:
- Endothelin-1 (ET-1) acts on ETA and ETB receptors and has been implicated in hemorrhagic shock (shock). We determined effect of shock and resuscitation by hypertonic saline (saline) or centhaquin on ETA and ETB receptor expression. Rats were anesthetized, a pressure catheter was placed in the left femoral artery; blood was withdrawn from the right femoral artery to bring mean arterial pressure (MAP) to 35 mm Hg for 30 min, resuscitation was performed and 90 min later sacrificed to collect samples for biochemical estimations. Resuscitation with centhaquin decreased blood lactate and increased MAP. Protein levels of ETA or ETB receptor were unaltered in the brain, heart, lung and liver following shock or resuscitation. In the abdominal aorta, shock produced an increase (140 %) in ETA expression which was attenuated by saline and centhaquin; ETB expression was unaltered following shock but was increased (79 %) by centhaquin. In renal medulla, ETA expression was unaltered following shock, but was decreased (-61 %) by centhaquin; shock produced a decrease (-34 %) in ETB expression which was completely attenuated by centhaquin and not saline. Shock induced changes in ETA and ETB receptors in the aorta and renal medulla are reversed by centhaquin and may be contributing to its efficacy., S. Briyal, R. Gandhakwala, M. Khan, M. S. Lavhale, A. Gulati., and Seznam literatury
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1969. 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
1970. 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