In ophthalmology, excimer lasers are used for treating different refractive disorders. The performance of an excimer laser station can be assessed by a number of criteria, such as cornea surface smoothness after the ablation, differences between the diameter of the postoperative optical zone that received full correction and the diameter of the programmed optical zone, and cornea heating during the surgery. The article presents the results of the assessment of three Russian excimer laser systems: MicroScan-PIC 100 Hz, MicroScan-Visum 300 Hz and MicroScan-Visum 500 Hz (Optosystems, Russia). The smoothness of the ablated surface was measured by New View – 5000 Zygo interferometer (Zygo Corporation, USA). Using PMMA plates, the ablated surface was formed tenfold with each laser as an imitation of the 3.0 D myopia surgical correction, with the optical zone diameter of 6 mm and the transition zone diameters of 2.3 mm for MicroScan-PIC 100 Hz and of 1.9 mm for MicroScan- Visum 300 Hz and MicroScan-Visum 500 Hz. Thermal processes in the cornea were studied in 15 grey chinchillas over 1 year old with a weight of 2–3 kg. With each of the laser systems, phototherapeutic keratectomy was performed on 5 eyes. The smoothest ablated surfaces were formed by MicroScan-Visum 500 Hz. Cornea temperature was the highest here (+3.95 °С by the end of treatment), but still within the range of values acceptable for modern scanning type lasers.
VIEWS 4682
Medicinal plant material is one of the sources of antioxidants for the human body. Chemiluminescence analysis is one of the common methods of determining the content of antioxidants in plant materials. In our work, chemiluminescence analysis was used to determine the total antioxidant capacity (TAC) of fruit decoctions of mountain-ash, rose and hawthorn, as well as raspberry fruit infusion. Experiments established the kinetics of the chemiluminescence of a system consisting of horseradish peroxidase, hydrogen peroxide and luminol. Concentrations and volumes of components of the system were chosen such that strong antioxidants (ascorbic acid) and antioxidants of average force (quercetin) were completely oxidized during measurement (10 minutes). A method for TAC calculation based on changes in chemiluminescence light sum in the presence of plant samples was proposed and substantiated. Analysis of chemiluminescence kinetics showed that antioxidants of average force dominate in the objects studied, including flavonoids and weak antioxidants (tocopherol and others). Comparison of the calculated TAC values for the objects under study and their chemical analysis data showed that products containing the same amount of antioxidants with different ratios of antioxidants by types might vary in their ability to protect the body against the harmful effects of free radicals. The technique described is a promising one for the study of plant objects containing a mixture of different types of antioxidants.
VIEWS 4834
Genetically modified animals are an important tool for biomedical research. The CRISPR/Cas9 editing genome system is increasingly being used for production of such animals. Through microinjection, complex with guide RNA and Cas9 protein is delivered in fertilized eggs from which the animal subsequently develops with a modification in the genome. Generally, analysis of the specificity and efficiency of the system in each case is carried out after obtaining a progeny with the likely mutation. However, analysis at the preimplantation stage would allow reducing the time of the experiment, as well as understanding the reason for the birth of a small number of transgenic animals, or even lack of them in the offsprings. The paper proposes a modification of the method of preparation of total DNA from mouse blastocysts. The modification allows to easier and faster detect the results of microinjection of the CRISPR/Cas9 complex in the zygote. Having applied the method described in this paper, we successfully identified short deletions in intron 34 of dystrophin gene (DMD) in 12 out of 13 treated embryos and insertion in the break site in intron 8 of the DMD gene in 11 out of 21 samples analyzed. Using for analysis the total DNA prepared by the method proposed, you can analyze up to 20 different sites in the mouse embryo genome at the blastocyst stage without the need for full genomic amplification.
VIEWS 5169