Differential sensitivity of brainstem vs cortical astrocytes to changes in pH reveals functional regional specialization of astroglia

Astrocytes might function as brain interoceptors capable of detecting different (chemo)sensory modalities and transmitting sensory information to the relevant neural networks controlling vital functions. For example, astrocytes which reside near the ventral surface of the brainstem (central respiratory chemosensitive area) respond to physiological decreases in pH with vigorous elevations in intracellular Ca(2+) and release of ATP. ATP transmits astroglial excitation to the brainstem respiratory network and contributes to adaptive changes in lung ventilation. Here we show that in terms of pH-sensitivity ventral brainstem astrocytes are clearly distinct from astrocytes residing in the cerebral cortex. We monitored vesicular fusion in cultured rat brainstem astrocytes using total internal reflection fluorescence microscopy and found that approximately 35% of them respond to acidification with an increased rate of exocytosis of ATP-containing vesicular compartments. These fusion events require intracellular Ca(2+) signaling and are independent of autocrine ATP actions. In contrast, the rate of vesicular fusion in cultured cortical astrocytes is not affected by changes in pH. Compared to cortical astrocytes, ventral brainstem astrocytes display higher levels of expression of genes encoding proteins associated with ATP vesicular transport and fusion, including vesicle-associated membrane protein-3 and vesicular nucleotide transporter. These results suggest that astrocytes residing in different parts of the rat brain are functionally specialized. In contrast to cortical astrocytes, astrocytes of the brainstem chemosensitive area(s) possess signaling properties which are functionally relevant – they are able to sense changes in pH and respond to acidification with enhanced vesicular release of ATP

Determination of the dimensions of the heat-affected zone in welding gas pipeline components

Analytical decisions supported by experimental data were used to determine the dependences for calculating the size of the heat-affected zone (HAZ) in multilayer welding of circumferential joints in transmission gas pipelines. Data on the dimensions of this zone are essential for evaluating the possibility of applying cold cutting in the rejection of elements of gas pipelines because of defects in circumferential welded joints or welded joints in transition rings in the vicinity of circumferential welded joints. © 2013 Copyright Taylor and Francis Group, LLC

Измерение удельной поверхности рыхлого осадка меди электрохимическими методами

In the work the surface area of the electrode with dispersed copper deposit obtained within 30 seconds was evaluated by techniques of chronopotentiometry (CPM) and impedance spectroscopy. In method CPM the electrode surface available for measurement depends on the value of the polarizing current. At high currents during the transition time there is a change of surface relief that can not determine the full surface of loose deposit. The electrochemical impedance method is devoid of this shortcoming since the measurements are carried out in indifferent electrolyte in the absence of current. The area measured by the impedance is tens of times higher than the value obtained by chronopotentiometry. It is found that from a solution containing sulfuric acid the deposits form with a high specific surface area. Based on these data it was concluded that the method of impedance spectroscopy can be used to measure in situ the surface area of the dispersed copper deposits.В работе проведена оценка площади поверхности электрода с дисперсным осадком меди, полученным в течение 30 секунд методами хронопотенциометрии (ХПМ) и импедансной спектроскопии. В методе ХПМ поверхность электрода, доступная для измерения, зависит от величины поляризующего тока. При больших токах в течение переходного времени происходит изменение рельефа поверхности, что не позволяет определить полную поверхность рыхлого осадка. Метод электрохимического импеданса лишен этого недостатка, так как измерения проводятся в индифферентном электролите в отсутствие тока. Площадь, измеренная методом импеданса, в десятки раз превышает значения, полученные методом хронопотенциометрии. Установлено, что из раствора, содержащего серную кислоту, формируются осадки с высокой удельной поверхностью. На основании полученных данных сделан вывод, что метод импедансной спектроскопии может быть использован для измерения in situ площади поверхности дисперсных осадков меди

Выбор условий получения электролитических порошков цинка для металлнаполненных композиций

The paper presents a method of obtaining high-dispersed zinc powders by electrolysis and comparison of the properties of zinc-rich compositions prepared using as a pigment zinc powders obtained by different methods. Measurements have shown that the electrical conductivity of zinc-rich coatings containing electrolytic zinc powder, not inferior to the conductivity of the film with powder PZHD-0 obtained by the method of evaporation-condensation, despite the significant difference in the amount of zinc pigment. On the basis of the received data we can conclude that the use of electrolytic zinc powder as a pigment will significantly save zinc.В работе представлен способ получения высокодисперсных порошков цинка электролизом и сравнение свойств цинкнаполненных композиций, приготовленных с применением в качестве пигмента цинковых порошков, полученных разными методами. Проведенные измерения показали, что удельная электропроводность цинкнаполненных покрытий, содержащих электролитический порошок цинка, не уступает по проводимости пленкам с порошком ПЦВД-0, полученного методом испарения-конденсации, несмотря на существенное различие в количестве цинкового пигмента. На основании полученных данных можно сделать вывод, что использование электролитического порошка цинка в качестве пигмента позволит значительно экономить цинк.This work was supported by RFBR, project number 11-03-00226.Работа выполнена при поддержке РФФИ, проект № 11-03-00226

Disentangling astroglial physiology with a realistic cell model in silico

Electrically non-excitable astroglia take up neurotransmitters, buffer extracellular K+ and generate Ca2+ signals that release molecular regulators of neural circuitry. The underlying machinery remains enigmatic, mainly because the sponge-like astrocyte morphology has been difficult to access experimentally or explore theoretically. Here, we systematically incorporate multi-scale, tri-dimensional astroglial architecture into a realistic multi-compartmental cell model, which we constrain by empirical tests and integrate into the NEURON computational biophysical environment. This approach is implemented as a flexible astrocyte-model builder ASTRO. As a proof-of-concept, we explore an in silico astrocyte to evaluate basic cell physiology features inaccessible experimentally. Our simulations suggest that currents generated by glutamate transporters or K+ channels have negligible distant effects on membrane voltage and that individual astrocytes can successfully handle extracellular K+ hotspots. We show how intracellular Ca2+ buffers affect Ca2+ waves and why the classical Ca2+ sparks-and-puffs mechanism is theoretically compatible with common readouts of astroglial Ca2+ imaging

A database of microRNA expression patterns in Xenopus laevis

MicroRNAs (miRNAs) are short, non-coding RNAs around 22 nucleotides long. They inhibit gene expression either by translational repression or by causing the degradation of the mRNAs they bind to. Many are highly conserved amongst diverse organisms and have restricted spatio-temporal expression patterns during embryonic development where they are thought to be involved in generating accuracy of developmental timing and in supporting cell fate decisions and tissue identity. We determined the expression patterns of 180 miRNAs in Xenopus laevis embryos using LNA oligonucleotides. In addition we carried out small RNA-seq on different stages of early Xenopus development, identified 44 miRNAs belonging to 29 new families and characterized the expression of 5 of these. Our analyses identified miRNA expression in many organs of the developing embryo. In particular a large number were expressed in neural tissue and in the somites. Surprisingly none of the miRNAs we have looked at show expression in the heart. Our results have been made freely available as a resource in both XenMARK and Xenbase

МИТОХОНДРИАЛЬНЫЙ БЕЛКОВЫЙ ПРОФИЛЬ И ЕГО РОЛЬ В ПАТОЛОГИЧЕСКИХ ПРОЦЕССАХ

Mitochondria import hundreds of different precursor proteins from the cytosol, and only 13 proteins are encoded by mtDNA itself. Recent investigations demonstrated real size of mitochondrial proteome and complexity of their functions There are many methods using for mitochondrial proteome profiling, that help to understand a molecular mechanisms of mitochondrial functions and identify the causes of disruptions that lead to different disorders. In this review we discuss a recent data in the field of mitochondrial proteomics.Собственная ДНК митохондрий кодирует лишь 13 полипептидов – субъединиц электронтранспортной цепи. Большинство же белков импортируются в митохондрии посредством различных механизмов. Последние исследования митохондриального протеома продемонстрировали истинные размеры и сложную функциональную организацию митохондриальных белковых профилей. Для протеомного профилирования митохондрий применяются различные технологии, которые в сумме представляют результаты, помогающие понять молекулярные механизмы функционирования органелл и выявить нарушения, приводящие к различным заболеваниям. В данном обзоре рассмотрены и проанализированны последние данные в области протеомики митохондрий и затронуты некоторые аспекты молекулярного патогенеза заболеваний дыхательной цепи

Measurement of the specific surface area of loose copper deposit by electrochemical methods

In the work the surface area of the electrode with dispersed copper deposit obtained within 30 seconds was evaluated by techniques of chronopotentiometry (CPM) and impedance spectroscopy. In method CPM the electrode surface available for measurement depends on the value of the polarizing current. At high currents during the transition time there is a change of surface relief that can not determine the full surface of loose deposit. The electrochemical impedance method is devoid of this shortcoming since the measurements are carried out in indifferent electrolyte in the absence of current. The area measured by the impedance is tens of times higher than the value obtained by chronopotentiometry. It is found that from a solution containing sulfuric acid the deposits form with a high specific surface area. Based on these data it was concluded that the method of impedance spectroscopy can be used to measure in situ the surface area of the dispersed copper deposits

THROMBOPHILIA AND INTENSITY OF THE INTRAVASCULAR MICROCOAGULATION IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE, ATHEROTHROMBOSIS

Aim. To study the intensity of the intravascular microcoagulation in patients with atherothrombosis (AT), chronic obstructive pulmonary disease (COPD) and thrombophilia.Material and methods. 115 patients were enrolled into the study: 37 patients with COPD (22 with thrombophilia and 15 without thrombophilia); 37 patients with AT (23 with thrombophilia and 14 without thrombophilia); 41 patients with COPD+AT (24 with thrombophilia and 17 without thrombophilia). In the control group 53 healthy people (39 with thrombophilia and 14 without thrombophilia) were included. Median age was 62 (56.5, 69) years. The intensity of intravascular microcoagulation was measured: platelet factor 4 (PF4) by ELISA, D-dimer by ELISA, XIIa-dependent fibrinolysis (time). Polymerase chain reaction was used for detection of such trombophilia parameters as Leiden mutation, prothrombin gene mutation 20210A, mutation in the gene of methylenetetrahydrofolate reductase (MTHFR) and plasminogen activator inhibitor-1 (PAI-1).Results. The level of PF4 and D-dimer was significantly higher while fibrinolytic activity was lower in COPD (103.5 ME/ml, 70 ng/ml, 650 s, respectively), AT (127.1 ME/ml, 96,9 ng/ml, 850 s, respectively) and COPD+AT (136.5 ME/ml, 106.5 ng/ml, 1148 s, respectively) groups as compared with the control group (p&lt;0.05). When analyzing the level of intravascular coagulation parameters in patients with thrombophilia and without it, levels of PF4, D-dimer and XIIa-dependent fibrinolysis (time) were significantly higher in thrombophilia subgroups among all patients (p&lt;0.05). In patients with thrombophilia levels of these parameters were significantly higher in those with two or more thrombophilia gene polymorphisms than with one (p&lt;0.01).Conclusion. The intensity of intravascular microcoagulation increases in patients with thrombophilia, atherothrombosis and COPD.</p