79 research outputs found

    Proton- and ammonium-sensing by histaminergic neurons controlling wakefulness

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    The histaminergic neurons in the tuberomamillary nucleus (TMN) of the posterior hypothalamus are involved in the control of arousal. These neurons are sensitive to hypercapnia as has been shown in experiments examining c-Fos expression, a marker for increased neuronal activity. We investigated the mechanisms through which TMN neurons respond to changes in extracellular levels of acid/CO2. Recordings in rat brain slices revealed that acidification within the physiological range (pH from 7.4 to 7.0), as well as ammonium chloride (5 mM), excite histaminergic neurons. This excitation is significantly reduced by antagonists of type I metabotropic glutamate receptors and abolished by benzamil, an antagonist of acid-sensing ion channels (ASICs) and Na+/Ca2+ exchanger, or by ouabain which blocks Na+/K+ ATPase. We detected variable combinations of 4 known types of ASICs in single TMN neurons, and observed activation of ASICs in single dissociated TMN neurons only at pH lower than 7.0. Thus, glutamate, which is known to be released by glial cells and orexinergic neurons, amplifies the acid/CO2-induced activation of TMN neurons. This amplification demands the coordinated function of metabotropic glutamate receptors, Na+/Ca2+ exchanger and Na+/K+ ATPase. We also developed a novel HDC-Cre transgenic reporter mouse line in which histaminergic TMN neurons can be visualized. In contrast to the rat, the mouse histaminergic neurons lacked the pH 7.0-induced excitation and displayed only a minimal response to the mGluR I agonist DHPG (0.5 μM). On the other hand, ammonium-induced excitation was similar in mouse and rat. These results are relevant for the understanding of the neuronal mechanisms controlling acid/CO2-induced arousal in hepatic encephalopathy and obstructive sleep apnoea. Moreover, the new HDC-Cre mouse model will be a useful tool for studying the physiological and pathophysiological roles of the histaminergic system

    The impact of secondary mineral formation on Na-K-geothermometer readings: a case study for the Valley of Geysers hydrothermal system (Kronotsky State Nature Biosphere Reserve, Kamchatka)

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    The temperature in the Valley of Geysers (Kamchatka) geothermal reservoir calculated using the feldspar Na-K-geothermometer has been steadily increasing over the past 10 years on average from 165 to 235 °C, which is close to the temperature values of a hydrothermal explosion of the steam and water mixture. For the analysis of chemical geothermometers, TOUGHREACT-simulation was used, with the help of which the previously known Na-K feldspar geothermometer was reproduced on a single-element model and new formulas were obtained for three Na-K geothermometers: zeolite, smectite, and based on volcanic glass. Data of chemical analysis for the period 1968-2018, in which the chloride ion is considered as an inert tracer of geofiltration processes, indicates that after 2007 a significant inflow of infiltration water (its mass fraction is estimated from 5 to 15 %) into the Geyser reservoir. It is assumed that the Na-K increased values of the feldspar geothermometer are not the result of the temperature increase in the Geyser reservoir, but the effect of smectite water dilution

    The Black Sea Region Energy Cooperation: Current Trends and Prospects

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    The Black Sea region is one of the most complex regions in terms of energy development. It hosts several major powers and some developing countries that need to cut energy costs. In general, the region is controversial. It is influenced by external actors, and therefore regional stability is very difficult to achieve. In addition, institutional players such as the EU, the Belt and Road Initiative, the Black Sea Trade and Development Bank, etc., have their own vision of the future of the Black Sea region. The article is aimed at assessing the regional balance of power and estimating the interests of the countries of the region. Based on this assessment, the authors have classified the countries in the region, predicted potential alliances, and provided recommendations on how the countries should behave in the region. The key findings comprise the rejection of the two hypotheses: the countries of the region cooperate mainly through similar institutions; and the countries of the region can efficiently cooperate within the framework of a single strategy. The novelty of the article is in a new look on the regional distribution of power and new strategies for cooperation between countries in the region.Keywords: The Black Sea region, energy sector, strategy, institutions, balance of powerJEL Classifications: F59, Q48DOI: https://doi.org/10.32479/ijeep.11247</p

    A photochemical approach for a fast and self-limited covalent modification of surface supported graphene with photoactive dyes

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    Herein, we report a simple method for a covalent modification of surface supported graphene with photoactive dyes. Graphene was fabricated on cubic-SiC/Si(001) wafers due to their low cost and suitability for mass-production of continuous graphene fit for electronic applications on millimetre scale. Functionalisation of the graphene surface was carried out in solution via white light induced photochemical generation of phenazine radicals from phenazine diazonium salt. The resulting covalently bonded phenazine-graphene hybrid structure was characterised by scanning tunnelling microscopy (STM) and spectroscopy (STS), Raman spectroscopy and density functional theory (DFT) calculations. It was found that phenazine molecules form an overlayer, which exhibit a short range order with a rectangular unit cell on the graphene surface. DFT calculations based on STM results reveal that molecules are standing up in the overlayer with the maximum coverage of 0.25 molecules per graphene unit cell. Raman spectroscopy and STM results show that the growth is limited to one monolayer of standing molecules. STS reveals that the phenazine-graphene hybrid structure has a band gap of 0.8 eV

    Дистальные тубулопатии. Синдром Гительмана

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    The clinical recommendations on management of children with Gitelman syndrome developed by the experts of the Union of pediatricians of Russia are presented in this article. Gitelman syndrome is a dysfunction of distal renal tubules with further development of hypomagnesemia, hypocalciuria and secondary aldosteronism which determine hypokalemia and metabolic alkalosis. Features of epidemiology, etiology and pathogenesis, disease progression, differential diagnostics and evidence-based treatment are presented.Представлены разработанные экспертами Союза педиатров России клинические рекомендации по оказанию медицинской помощи детям с синдромом Гительмана — нарушением функции дистальных почечных канальцев с развитием гипомагнеземии, гипокальциурии и вторичного альдостеронизма, который обусловливает гипокали-емию и метаболический алкалоз. Отмечены особенности эпидемиологии, этиологии и патогенеза, клинического течения, дифференциальной диагностики, а также лечения, основанного на принципах доказательности

    Петлевые тубулопатии: синдром Барттера

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    The authors provide a review of current clinical guidelines regarding medical care provided to children with Bartter’s syndrome — impaired renal tubular function (loop of Henle) with the development of hypokalemia, hypochloremia, metabolic alkalosis and hyperreninemic hyperaldosteronism.  The specifics of disease epidemiology, etiology and pathogenesis  are described. The issues of differential diagnosis and treatment based on the principles of evidence are covered.Авторами  представлены   основные  положения   актуальных  клинических  рекомендаций  по  оказанию  медицинской помощи детям с синдромом Барттера  — нарушением функции  почечных канальцев  (петли  Генле)  с развитием гипокалиемии,  гипохлоремии,  метаболического  алкалоза  и гиперренинемического  гиперальдостеронизма. Рассматриваются  особенности  эпидемиологии,  этиологии  и патогенеза.  Освещены вопросы дифференциальной диагностики, лечения, основанного на принципах доказательности

    The waking brain: an update

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    Wakefulness and consciousness depend on perturbation of the cortical soliloquy. Ascending activation of the cerebral cortex is characteristic for both waking and paradoxical (REM) sleep. These evolutionary conserved activating systems build a network in the brainstem, midbrain, and diencephalon that contains the neurotransmitters and neuromodulators glutamate, histamine, acetylcholine, the catecholamines, serotonin, and some neuropeptides orchestrating the different behavioral states. Inhibition of these waking systems by GABAergic neurons allows sleep. Over the past decades, a prominent role became evident for the histaminergic and the orexinergic neurons as a hypothalamic waking center

    The Bilinear Pairings for the Holomorphic (q,p)-Forms

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    В работах [1, 2] начато изучение нормированных пространств голоморфных мультипликативных автоморфных форм для фуксовой группы. В данной работе исследуются билинейные спаривания в этих пространствах в связи с общей (q,p)-двойственностью форм. Получено "симметричное" билинейное спаривание, которое можно использовать и в теории однозначных автоморфных форм. На основе введенных билинейных спариваний строятся мультипликативные операторы Берса, связанные с отражением относительно квазиокружности и устанавливающие связь между двойственными пространствами голоморфных форм для общей (q,p)-двойственности. Для всех операторов получена универсальная оценка нормы.Study was started in [1,2] of the normed spaces of multiplicative holomorphic automorphic forms for a Fuchsian group. In the present article bilinear pairings for general duality of the (q,p)-forms are considered. The symmetric variant of bilinear pairing which can be used in the theory of single-valued automorphic forms is received. On the basis of the entered bilinear pairings the modified integral Bers operators corresponding to them are investigated. These operators relate to a reflection in some quasicircle and also are connected to the general duality of (q,p)-forms. Under study the universal norm estimates for all operators is received
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