Genetically encoded fluorescent sensors are exploited to study a variety of biological processes in living organisms in real time. In recent years, a whole family of biosensors has been developed, serving to visualize changes in the glutathione redox state. The aim of our experiment was to design a biosensor based on the red fluorescent protein mKate2 for measuring the 2GSH/GSSG ratio. A pair of cysteine amino acid residues were introduced into the structure of the fluorescent protein using site-directed mutagenesis. These residues form a disulfide bridge when the surrounding glutathione pool is oxidized, affecting the spectral characteristics of the protein. Our biosensor, which we called roKate, was tested in vitro on an isolated protein. Specifically, we examined the spectral characteristics, pH and the redox potential of the sensor. Additionally, the performance of roKate was evaluated using the culture of living mammalian cells. The fluorescent signal emitted by the sensor was very bright and remarkably stable under pH conditions varying in the physiological range. Irreversibly oxidized in mammalian cells, roKate stands out from other members of this biosensor family. This biosensor should be preferred in the experiments when the time between the manipulations with the biological object and the subsequent analysis of the induced effect is substantial, as is the case with long sample preparation.
VIEWS 5174
Today, increasing attention is being paid to the role of circadian rhythms in pathology. There are time-of-day-dependent immune markers that provide valuable information about disease progression. The aim of this study was to measure evening and morning concentrations of a few cytokines (interleukins, adhesion molecules, tumor necrosis/growth factors, etc.) in the peripheral blood of patients with stage II essential hypertension and to investigate how they correlate with a nocturnal blood pressure decline. Blood samples were collected from 90 patients with stage II EH at 7:00 a.m. and 8:00 p.m. Cytokine concentrations were measured using immunoassays. Based on 24-h blood pressure monitoring, the patients were distributed into 3 groups: dippers, non-dippers and night-peakers. The morning to evening ratios of cytokine concentrations in patients with EH differed from those in healthy controls due to an increase in the evening concentrations of somnogenic cytokines (IL1β, IL1α) and LIF, sLIFr, and M-CSF whose daily fluctuations patterns remain understudied. On the whole, the fluctuation patterns of the measured cytokines in patients with stage II EH who had had the condition for 10 to 14 years and were receiving no antihypertensive treatment at the time of our study differed from those displayed by healthy controls. A twenty percent rise in the evening concentrations of IL1α, LIF, sLIFr, M-CSF, and erythropoietin contributes significantly to pathological blood pressure rhythms (as demonstrated by the groups of non-dippers and night-peakers) in patients with stage II EH receiving no antihypertensive therapy. Understanding the pathophysiological role of cytokine levels and their fluctuations over a 24-h cycle could inspire new methods for EH prevention and reduce end-organ damage.
VIEWS 4850
To a large extent, age-related facial skin changes, wrinkles and flabbiness, are attributed to the structural alterations in dermis, including of collagen fibers fragmentation and disorganization. There are various cosmetological correction methods that aim to activate neocollagenesis and dermal remodeling. From this perspective, intradermal injections of exogenous collagen preparations seem logical. This study aimed to investigate the efficacy and safety of Collost 7% collagen complex applied to correct the age-related facial skin changes, as well as clarify the possible mechanisms of skin rejuvenation resulting from a course of intradermal injections. 35 participants entered the study, 30 of them finished it. A set of indicators describing age-related skin changes was assessed with the help of clinical scales; the assessment revealed a pronounced improvement in the quality of the patients' skin, including smoothed relief in the area of localization of fine wrinkles. The therapy resulted in a statistically significant improvement of the skin's elasticity, which, combined with the changes discovered through US scanning (greater dermis thickness and echodensity), is an indirect indication of skin restructuring associated with accumulation of fibrous protein structures. These results allow parallels with the experimental data that shows activation of neocollagenesis in the skin of laboratory animals after a course of Collost 7% gel. The research revealed no serious adverse events. A course of collagen administered intradermally can be recommended as an aesthetic correction procedure, as well as means of prevention of atrophy that has a significant effect on skin's appearance and health status.
VIEWS 5173
With each year, millions of people remain targeted by brain stroke, it still is by all means a global concern of the mankind. Despite all efforts to understand this disease better, there is still a lack of information on pathophysiology of ischemic stroke. Scrutinized data on biochemical changes at early stages of ischemia may help understand the mechanisms of the disorder and possibly reveal ways to finding the cure. The key role in the pathogenesis of stroke belongs to lipids as well as to the molecules associated with their biosynthesis and functionality. On the one hand, stroke evokes a deep oxidative stress leading to damage to biomolecules including lipids while on the other hand, due to the lack of reducing equivalents, the cellular biosynthesis processes are interrupted. The focus of this work was to study the changes taking place in the tissues of rat brain as a result of ischemia including estimation of levels of total cholesterol, FFA, MDA, GSH, and NADP(H). It was shown that in 24 hours from the onset of ischemia, there was a significant decrease in levels of FFA, total cholesterol and GSH, and an increase in the level of MDA, a marker of lipid peroxidation. NADP(H) pool level decreases twice in 6 hours from MCAO.
VIEWS 4985
To identify genetic mutations a rather time-consuming and expensive method of polymerase chain reaction (PCR) is widely used. The aim of the present work was to evaluate the possibility of using the two schemes of the method of allele-specific isothermal loop amplification (LAMP) to detect the TCG/TTG (S450L) mutation in the rpoB gene of Mycobacterium tuberculosis. 48 clinical isolates of M. tuberculosis and 11 samples of sputum were used, randomized and obtained in the microbiological laboratory of the city of Novosibirsk from incident patients. It is shown that the use of an analysis scheme using the allele-specific primer FIP compared to F3 has the best resolution: the difference between the amplification time of the mutation and the wild type allele was 22 ± 2,4 versus 13 ± 4,1 minutes (p = 0,0011). When using 100 DNA genomic equivalents a true positive signal (amplification of the rpoB gene with a mutation using the corresponding allele-specific primer) was detected after 29,4 ± 3,4 minutes. A positive signal was visualized after adding SYBR Green I to the reaction, both when illuminated with daylight and when using a UV transilluminator. Using the developed method the DNA sample of 20 RIFR isolates from M. tuberculosis was analyzed containing the Ser450Leu mutation in the rpoB gene, 10 RIFR isolates containing other mutations in the rpoB gene and 18 RIFs isolates without any mutations; the presence of mutations in the samples was determined using classical Sanger sequencing. The sensitivity and specificity of LAMP for detecting a Ser450Leu mutation in the rpoB gene was 100%. This approach allows the use of crude lysates of mycobacteria as DNA, which reduces the total analysis time to 1,5 hour.
VIEWS 5218