Intestinal Microbial-tissue Complex and Chronic Heart Failure (part 1): Pathogenesis

Antigenic and metabolic integration of the intestinal microbiota into the homeostasis of the human body is a factor that claims to play a key role in the pathogenesis of cardiovascular diseases. It acquires special significance against the background of the decrease in blood circulation and congestion in the digestive system during chronic heart failure. Aim of the review is analysis and synthesis of studies results on the role of intestinal microbiocenosis in the pathogenesis of heart remodeling and chronic heart failure. The search for articles was conducted in databases eLIBRARY.RU and Medline for the key terms "gut microbiota (microbiome, microbiocenosis)", "dysbiosis (dysbacteriosis)", "excessive bacterial growth syndrome", "lipopolysaccharide (endotoxin)", "trimethylamine-N-oxide" in combination with the terms "heart failure", "myocardial remodeling", "myocardium" in Russian and English, respectively. We selected articles containing the results of clinical and experimental studies published from 1995 to 2020. Review articles were considered only on the subject of the cited original publications. Most researchers have established the relationship between chronic heart failure and dysfunction and changes in the qualitative and quantitative composition of intestinal microbiocenosis. As negative changes, it is customary to note the proliferation of gram-negative opportunistic bacteria with concomitant endotoxinemia and a decrease in the pool of commensal microbiota. The available data suggest that the participation of the intestinal microbial-tissue complex in the pathogenesis of chronic heart failure and heart remodeling is realized through the activation of a local and then systemic inflammatory response, accompanied by cardiodepressive action of pro-inflammatory cytokines and universal proliferation factors, an imbalance of matrix metalloproteinases and their inhibitors, the initiation of apoptosis, fibrosis, and loss of contractile myocardium. Besides, a decrease in the production of short-chain and polyunsaturated fatty acids and vitamins by the commensal microbiota may be associated with changes in the electrical properties of cardiomyocyte membranes, a decrease in the systolic function of the left ventricle of the heart, and an increase in the risk of sudden cardiac death. It's also shown that the direct cardiotoxic effect of microbial molecules (lipopolysaccharides, peptidoglycans, trimethylamine-N-oxide, etc.), which interact with the receptors of cardiomyocytes and microenvironment cells, can cause the development of myocardial remodeling and its dysfunction. Recent studies have established mechanisms of myocardial remodeling mediated by microbial molecules, which may be associated with new strategies for the treatment and prevention of heart failure

The Megapixel EBCCD: a high-resolution imaging tube sensitive to single photons

A hybrid image-intensifier tube, suitable for extremely low-light imaging, has been tested. This device is based on an Electron-Bombarded CCD chip (EBCCD) with $1024 \times 1024$ sensitive pixe ls. The tube, which has a photocathode diameter of 40 mm, is gateable and zoomable, with an image magnification varying from 0.62 to 1.3. The high gain (about 4000 collected electrons per photo electron at the operational voltage of 15 kV) and the relatively low noise (180 electrons per pixel at 10 MHz pixel-readout frequency), allows single-photoelectron signals to be separated from n oise with a signal-to-noise ratio greater than 10. By applying an appropriate threshold on the signal amplitude, the background can almost be eliminated, with a loss of few percent in single-ph otoelectron counting. High inner gain, low noise, single-photoelectron sensitivity, and high spatial resolution make the EBCCD imaging tube a unique device, attractive for many applications in h igh-energy physics, astrophysics, biomedical diagnostics

A high-resolution tracking hodoscope based on capillary layers filled with liquid scintillator

Results are given on tests of a high-resolution tracking hodoscope based on layers of \hbox{26-$\mu$m-bore} glass capillaries filled with organic liquid scintillator (1-methylnaphthalene doped with R39). The detector prototype consisted of three 2-mm-thick parallel layers, with surface areas of $2.1 \times 21$~cm$^2$. The layers had a centre-to-centre spacing of 6~mm, and were read by an optoelectronic chain comprising two electrostatically focused image intensifiers and an Electron-Bombarded Charge-Coupled Device (EBCCD). Tracks of cosmic-ray particles were recorded and analysed. The observed hit density was 6.6~hits/mm for particles crossing the layers perpendicularly, at a distance of 1~cm from the capillaries' readout end, and 4.2~hits/mm for particles at a distance of 20~cm. A track segment reconstructed in a single layer had an rms residual of $\sim$~20~$\mu$m, and allowed determination of the track position in a neighbouring layer with a precision of $\sim$~170~$\mu$m. This latter value corresponded to an rms angular resolution per layer of about 30~mrad. A comparison is made between capillary layers and silicon microstrip planes