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31672. The role of nitric oxide in the maintenance of vasoactive balance
- Creator:
- Oľga Pecháňová and Fedor Šimko
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, oxid dusnatý, endoteliální dysfunkce, hypertenze, nitric oxide, endothelial dysfunction, hypertension, angiotensin II, endothelins, reactive oxygen species, 14, and 612
- Language:
- English
- Description:
- Endothelial dysfunction may be considered as the interstage between risk factors and cardiovascular pathology. An imbalance between the production of vasorelaxing and vasoconstricting factors plays a decisive role in the development of hypertension, atherosclerosis and target organ damage. Except vasorelaxing and antiproliferative properties per se, nitric oxide participates in antagonizing vasoconstrictive and growth promoting effects of angiotensin II, endothelins and reactive oxygen species. Angiotensin II is a potent activator of NAD(P)H oxidase contributing to the production of reactive oxygen species. Numerous signaling pathways activated in response to angiotensin II and endothelin-1 are mediated through the increased level of oxidative stress, which seems to be in casual relation to a number of cardiovascular disturbances including hypertension. With respect to the oxidative stress, the NO molecule seems to be of ambivalent nature. On the one hand, NO is able to reduce generation of reactive oxygen species by inhibiting association of NAD(P)H oxidase subunits. On the other hand, when excessively produced, NO reacts with superoxides resulting in the formation of peroxynitrite, which is a free radical deteriorating endothelial function. The balance between vasorelaxing and vasoconstricting substances appears to be the principal issue for the physiological functioning of the vascular bed., O. Pecháňová, F. Šimko., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31673. The role of non-aromatizable testosterone metabolite in metabolic pathways
- Creator:
- Michaela Dušková and Pospíšilová, H.
- Format:
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, ateroskleróza, testosteron, atherosclerosis, testosterone, non-aromatizable androgen, adipose tissue, metabolic syndrome, 14, and 612
- Language:
- English
- Description:
- Dihydrotestosterone (DHT) originates via irreversible reduction of testosterone by catalytic activity of 5α-reductase enzyme and it is demonstratively the most effective androgen. Androgens influence adipose tissue in men either directly by stimulation of the androgen receptor or indirectly, after aromatization, by acting at the estrogen receptor. DHT as a non-aromatizable androgen could be responsible for a male type fat distribution. The theory of non-aromatizable androgens as a potential cause of a male type obesity development has been studied intensively. However, physiological levels of DHT inhibit growth of mature adipocytes. In animal models, substitution of DHT in males after gonadectomy has a positive effect on body composition as a testosterone therapy. Thus, DHT within physiological range positively influences body composition. However, there are pathological conditions with an abundance of DHT, e.g. androgenic alopecia and benign prostatic hyperplasia. These diseases are considered as ri sk factors for development of metabolic syndrome or atherosclerosis. In obese people, DHT metabolism in adipose tissue is altered. Local abundance of non- aromatizable androgen has a nega tive effect on adipose tissue and it could be involved in pathogenesis of metabolic and cardiovascular diseases. Increased DHT levels, compared to physiological levels, have negati ve effect on development of cardiovascular diseases. Difference between the effect of physiological and increased level brings about certain paradox., M. Dušková, H. Pospíšilová., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31674. The role of oxygen in photosynthesis
- Creator:
- Vácha, F.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Oxygen can afFect the photosynthetic processes in two antagonistic (protective and destructive) ways. The protection is represented by draining off of the electron transport systém, by utilisation of NADPH and ATP, and production of carbon dioxide in the process of photorespiration, oxygen reduction in the Mehler reaction, and also by regeneration of monodehydroascorbate, one of the fmal products of the Mehler-peroxidase reaction. The subsequent building up of the proton gradient in the Mehler and Mehler-peroxidase reactions also helps protéct the photosynthetic apparatus. The production of harmful oxygen radicals is accompanied by the Mehler reaction. This is in contrast to the fact that the Mehler reaction can also protéct the photosynthetic apparatus. Nevertheless, the scavenging mechanisms in plants are efficient enough for protection against the active oxygen species. In some cases the disproportion between the production and scavenging of active oxygen can result in the destruction of thylakoid membrane. Singlet oxygen, another toxic form of oxygen, can also significantly increase the inhibition of photosynthesis in the presence of oxygen. None of these processes works alone or independently, they are in a dynamic equilibrium and each of them contributes to the regulation of photosynthesis.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31675. The role of photosynthetic activity in the regulation of flg22-induced local and systemic defence reaction in tomato
- Creator:
- Czékus, Z., Koprivanacz, P., Kukri, A., Iqbal, N., Ördög, A., and Poór, P.
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- assimilation, flagellin, mycotoxin, photosystem II, and stomatal conductance
- Language:
- Multiple languages
- Description:
- Flagellin (flg22) induces rapid and long-lasting defence responses. It may also affect the photosynthetic activity depending on several internal and external factors, such as the phytohormone ethylene or the day/night time. Based on the results, flg22 treatment, neither in the light phase nor in the evening, caused any significant change in chlorophyll fluorescence induction parameters in the leaves of wild-type and ethylene-receptor mutant Never ripe tomato plants measured the next morning. However, flg22 in the light phase decreased the effective quantum yield and the photochemical quenching both locally and systemically in guard cells. In parallel, the production of reactive oxygen species and nitric oxide increased, which contributed to the stomatal closure and a decrease in CO2 assimilation the next day. A decrease in sugar content and elevated hexokinase activity measured after flg22 exposure can also contribute to local defence responses in intact tomato plants.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31676. The role of policy rule misspecification in monetary policy inertia debate
- Creator:
- Podpiera, Jiří, Univerzita Karlova. Centrum pro ekonomický výzkum a doktorské studium, and Národohospodářský ústav (Akademie věd ČR)
- Publisher:
- CERGE-EI
- Format:
- electronic and 34 s.
- Type:
- model:monograph and TEXT
- Subject:
- Finance, matematické modelování, měnová politika, 336.74:338.23, 519.673, (048.8), 4, and 336.7
- Language:
- English
- Description:
- Jiří Podpiera. and born digital
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31677. The role of pulmonary artery wedge pressure on the incidence of atrial fibrillation and atrial tachycardias in patients with isolated pre-capillary pulmonary hypertension
- Creator:
- Dusik, Milan, Fingrova, Zdenka, Ambroz, David, Jansa, Pavel, Linhart, Ales, and Havranek, Stepan
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- pulmonary hypertension, atrial fibrillation, atrial tachycardia, atrial flutter, and pulmonary artery wedge pressure
- Language:
- English
- Description:
- Atrial fibrillation and atrial tachycardias (AF/AT) have been reported as a common condition in patients with pulmonary hypertension (PH). As yet, limited data exists about the significance of the borderline post-capillary pressure component on the occurrence of AF / AT in patients with isolated pre-capillary PH. We retrospectively studied the prevalence of AF / AT in 333 patients (mean age 61±15 years, 44 % males) with pre-capillary idiopathic / familiar pulmonary arterial hypertension, and inoperable chronic thromboembolic pulmonary hypertension. The prevalence of AF / AT was analyzed in different categories of pulmonary artery wedge pressure (PAWP). In the study population overall, the mean PAWP was 10.5±3 mmHg, median of 11 mmHg, range 2-15 mmHg. AF / AT was diagnosed in 79 patients (24 %). The proportion of AF / AT among patients with PAWP below the median (≤11 mmHg) was lower than in subjects with PAWP between 12 and 15 mmHg, 30 (16 %) vs. 46 (35 %), p=0.0001. Compared to the patients with PAWP≤11 mmHg, subjects with PAWP between 12 and 15 mmHg were older (65±13 years vs. 58±16), with more prevalent arterial hypertension [100 (70 %) vs. 106 (55 %)] and diabetes mellitus [50 (35 %) vs. 48 (25 %)], showed larger size of the left atrium (42±7 vs. 40±6 mm), and higher values of right atrium pressure (12±5 vs. 8±5 mmHg), p<0.05 in all comparisons. The prevalence of AF / AT in the group studied increased with the growing post-capillary component.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31678. The role of renin-angiotensin system in prothrombotic state in essential hypertension
- Creator:
- Anna Remková and Milan Remko
- Format:
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, endotel, hypertenze, endothelium, hypertension, platelet, coagulation, fibrionolysis, 14, and 612
- Language:
- English
- Description:
- Rheological, haemostatic, endothelial and platelet abnormalities appear to play a role in the thrombotic complications of hypertension. This prothrombotic/hypercoagulable state in hypertension may contribute to the increased risk and severity of target organ damage. It can be induced by the activated reninangiotensin system (RAS), with abnormalities in endothelial and platelet function, coagulation and fibrinolysis. Treatment of uncomplicated essential hypertension by RAS targeting antihypertensive therapy could result in a reversal of prothrombotic abnormalities, contributing to a reduction of thrombosis-related complications. Since angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) have two distinct mechanisms of RAS interruption, it is hypothesized that each therapy might have different impact on the prothrombotic state in hypertensive patients. Some studies demonstrate a beneficial effect of both ACE inhibitors and ARBs on prothrombotic state, in addition to their efficacy to normalize elevated blood pressure. The potentially antithrombotic effect of the RAS inhibiting agents may in turn support the preservation of cardiovascular function. Available data may offer an additional explanation for the efficacy of the RAS targeting agents in the prevention of cardiovascular events in patients with atherosclerotic vascular disease., A. Remková, M. Remko., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31679. The role of serotonergic system in body temperature regulation
- Creator:
- Nagai, M.
- Type:
- article, model:article, and TEXT
- Subject:
- thermoregulation, vascular responses, and serotonin
- Language:
- English
- Description:
- Results indicate that vascular responses to temperature stimulation are predominantly impaired in animals with 5-HT deprivation. A hypothesis is therefore raised that the 5-HT system participates in body temperature regulation in such a way asto link the regulatory output with vasomotor pathways. The 5-HT system in the spinal cord has been shown to inhibit the afferent transmission of temperature signals. Therefore, depletion of 5-HT does not prevent sensory transmission, at least at the spinal cord level.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
31680. The role of sexually dimorphic medial preoptic area of the hypothalamus in the sexual behaviour of male and female rats
- Creator:
- Kartha, K. N. B. and Ramakrishna, T.
- Type:
- article, model:article, and TEXT
- Subject:
- neonatal gonadectom, sexually dimorphic medial preoptic area, multiunit electrical activity, MPOA volume, testosterone propionate, and sexual behaviour
- Language:
- English
- Description:
- The neonatally gonadectomized male rats failed to show typical male clasping of the flanks of the female rat in oestrous stage and also could not achieve intromission and ejaculation when studied at 90 days of age. The replacement of testosterone propionate did not abolish the deficit in sexual behaviour observed. The multiunit electrical activity (MUA) in the medial preoptic area (MPOA) of intact males as well as of oestrous females increased significantly in amplitude and frequency from the low basal levels during mounting, but reverted almost to the basal levels after mounting. The basal MUA in the gonadectomized male rats was of relatively high frequency and amplitude when compared to the intact males and oestrous females, and did not show significant changes during and after mounting. It is suggested that the dimorphic organization of MPOA, developing under the influence of neonatal testosterone, plays a significant role in the male sexual behaviour in adulthood.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public