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Russian Science: Digest

Sialic acids play an important role in pathological processes in the body and some of them, for example, N-acetylneuraminic acid, are "responsible" for the carcinogenic processes. Group of researchers from the Institute of Bioorganic Chemistry RAS and Queen's University in Canada together with the Institute of Macromolecular Compounds RAS has shown that if the right to adjust the level of sialic acid, it’s possible to manipulate cancer cells and may stop the spread of metastases. Research results were published in Oncotarget Journal.

Sialic acid is often located on the surface of tumor cells. It gives them a negative charge and due to the repulsive forces contributes to their separation from the primary tumor. As a result, the tumor cells can spread throughout the body, forming secondary foci - metastasis.

Russian-Canadian group of scientists clarified the role of sialic acids in the development of cancer and cancer cells interacting with each other.

"We compared two versions of the attachment of sialic acid to the cell surface - through α-2,3 and α-2,6 links - Roman Akasov, junior research associate of the laboratory of polymers for biology of Institute of Bioorganic Chemistry RAS, one of the authors of the article, explains. - Both options of the bonds present in the cell and, despite the fact that their structure appears similar, even a slight difference may be important for the cell itself. We put the experiment on tumor spheroids - dense clusters of cells that mimic growth and behavior of real cells in tumor.

сиаловая_кислота

To do this, my colleagues and I have developed a method of forming such spheroids. They are formed not by physical strength, but due to changes in cell behavior: if add to them a small amount of a special peptide, they begin to migrate and self-agglomerate into small spherical structures, each of them consists of several hundreds of individual cancer cells. Since this method does not require any mixing of substances or any other severe physical intervention in the life of the cell, it is well suited for the study of thin biochemical factors that influence the ability of cells to form spheroids."

Roman and his colleagues found that the increase in the number of α-2,3 links and reducing the level of α-2,6 links of sialic acid lead to greater adhesion of cells in spheroids.

In the context of the body it is most likely a good sign: the stronger the tendency of cells to communicate with each other, the less likely that one of them will separate and give rise to new tumor.

If suppress the work of enzymes that get rid of the sialic acid, the cells also more likely stick together.

It acts as an antiviral drug oseltamivir. Queen's University staff has shown that it affects the formation of metastases. They have entered drug in a blood of mice and blocked enzymes which remove sialic acid from the cell surface, and suppressed the formation of secondary tumor lesions in the negative three most dangerous breast cancer.

Interestingly, that the antiviral effect of oseltamivir, which can be bought in a pharmacy under the brand name "Tamiflu", is blamed for the fact that it does not cure the flu, but, apparently, the drug copes with cancer.

If you go the other way and manually remove the acid from the surface of a cell or block its links, the tumor spheroids are not formed.

Using tumor spheroids as a test-system will allow to find new drugs that modulate cell aggregation, and bring us closer to understanding the biology of cancer.

New x-ray

The main trend of development of modern analytical instrument making is creation of compact desktop measuring systems of table-top and palm-top types. For their practical implementation in the X-ray analysis and diagnostic systems, which play a crucial role in medicine, industry and research, we need a compact and bright microfocus X-ray sources.

LPI RAS specialists together with partners from the LLC "MELZ", FSUE RPE "Istok" and LLP "Angstrem" solved this problem successfully. Alexander Tur'yanskii, the head of the Laboratory of X-ray diagnostic techniques of nanostructures LPI, doctor of physical and mathematical sciences says:

"We have developed a prototype of compact microfocus X-ray generator with a focus size of about 10 microns. Actually the radiation source is a miniature X-ray tube with 20 mm in diameter and 75 mm in length. Of course, the microfocus X-ray sources are not new.

They are made by a number of leading companies in the USA, Japan and Germany, and widely used for the inspection of industrial products and in biomedical diagnostics area. But they are based on the overall magnetic focusing systems. In the case of our tube two-stage system of electrostatic focusing of electrons is installed. It allowed to eliminate the magnetic focusing systems and dramatically reduce the size, weight and energy consumption. In particular, our tube weighs about 20 g.”

рентген

Another principal feature of the new source is that the thin film metal anode is deposited on an optically transparent diamond substrate, which is simultaneously the outlet of the tube. Firstly, record high thermal conductivity of diamond allows to increase manyfold the brightness of the X-ray focus. Secondly, the optimal choice of the thickness of the thin film anode and accelerating voltage by falling electrons at the anode, intense X-ray radiation in the metallic film and optical radiation in the diamond substrate are generated simultaneously.

Эксперимент

The position and size of the optical and X-ray foci are almost aligned.

Due to transparency of diamond substrate in the X-ray and optical ranges, X-ray radiation becomes visible!

Моноблок

These characteristics of the developed source open up new opportunities for widespread use: industry (control of defects, a local analysis of the composition and structure), in biomedical diagnostics and research analytics. By using X-ray focusing mirrors and polycapillaries radiation fluxes can be increased a hundredfold. The source was patented in Russia, and now together with the LLP "Angstrem" is patented in the USA and Europe.

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