Chemical analysis of bioactive substances in seven siberian Saussurea species

Main groups of biologically active substances of seven siberian Saussurea species (S. controversa DC., S. latifolia Ledeb., S. parviflora (Poir.) DC., S. frolowii Ledeb, S. amara (L.) DC., S. salicifolia (L.) DC. and S. daurica Adams) have been studied using paper, thin-layer, performance liquid chromatography, IR spectroscopy, spectrophotometry and mass spectrometry with inductively coupled plasma. Siberian Saussurea species have a rich elemental composition and contain a variety of phenolic compounds, amino acids, polysaccharides. The majority of polysaccharides are accumulated by S. controversa, S. salicifolia and S. frolowii. These plants contain a significant amount of calcium that may be a species characteristic. All plants contain quercetin and its glycosides, in some species luteolin, kaempferol, glycosides of apigenin and myricetin were revealed. Phenolic acids with predominant content of caffeic, chlorogenic and cinnamic acids were found in all the species. The maximum amount of phenolic acids and flavonoids was determined in the grass of S. latifolia, S. controversa and S. daurica. Characteristic absorption bands of lactone carbonyl of sesquiterpenoids in IR spectrum found in S. latifolia, S. controversa, S. daurica, S. amara and S. salicifolia. HPLC / UV analysis showed that peaks with absorption maxima of 242-246 nm due to the presence of α,β-unsaturated ketone group in the structure of ecdysteroids were found in S. salicifolia, S. controversa, S. daurica and S. latifolia

Toxic properties and allelopathic activity of Melilotus officinalis (L.) Pall.

Melilotus officinalis (L.) Pall., known as yellow sweetclover (Fabaceae), is widely used in medicine and agriculture. At the same time, yellow sweetclover is a weed and invasive plant in Siberia. In Russia, M. officinalis is cultivated as a valuable medicinal, fodder and honey plant. Its widespread use is due to its high ecological plasticity. In recent years, an interest in cultivation of M. officinalis as a low maintenance multipurpose crop has increased in biological agriculture. The herb M. officinalis contains a rich complex of biologically active compounds. However, along with positive properties, this species, though with a rich chemical composition and high physiological activity, is toxic towards different groups of living organisms. The toxic effect of M. officinalis extracts is primarily due to the presence of coumarin. A high allelopathic activity of M. officinalis was revealed. The phytotoxic effect of herb extracts on germination of crop and weed seeds was studied in detail. Data on the fungicidal and insecticidal activity of M. officinalis were obtained. Laboratory and in situ studies showed that the aboveground part of M. officinalis is a potential source of biopesticides with a broad-spectrum effect (bioherbicidal, insecticidal and fungicidal)

A BK channel–mediated feedback pathway links single-synapse activity with action potential sharpening in repetitive firing

Action potential shape is a major determinant of synaptic transmission, and mechanisms of spike tuning are therefore of key functional significance. We demonstrate that synaptic activity itself modulates future spikes in the same neuron via a rapid feedback pathway. Using Ca2+ imaging and targeted uncaging approaches in layer 5 neocortical pyramidal neurons, we show that the single spike–evoked Ca2+ rise occurring in one proximal bouton or first node of Ranvier drives a significant sharpening of subsequent action potentials recorded at the soma. This form of intrinsic modulation, mediated by the activation of large-conductance Ca2+/voltage-dependent K+ channels (BK channels), acts to maintain high-frequency firing and limit runaway spike broadening during repetitive firing, preventing an otherwise significant escalation of synaptic transmission. Our findings identify a novel short-term presynaptic plasticity mechanism that uses the activity history of a bouton or adjacent axonal site to dynamically tune ongoing signaling properties

Point mutations affecting yeast prion propagation change the structure of its amyloid fibrils

We investigated the effect of the point substitutions in the N-terminal domain of the yeast prion protein Sup35 (Sup35NMp) on the structure of its amyloid fibrils. As the objects of the study, proteins with mutations that have different influence on the [PSI+] prion propagation, but do not prevent the aggregation of Sup35NMp in vitro were chosen. The use of the wide range of physico-chemical methods allowed us to show significant differences in the structure of these aggregates, their physical size, clumping tendency. Also we demonstrated that the fluorescent probe thioflavin T (ThT) can be successfully used for investigation of subtle changes in the structural organization of fibrils formed from various Sup35NMp. The obtained results and our theoretical predictions allowed us to conclude that some of selected amino acid substitutions delimit the region of the protein that forms the core of amyloid fibrils, and change the fibrils structure. The relationship of structural features of in vitro Sup35NMp amyloid aggregates with the stability of the [PSI+] prion in vivo allowed us to suggest that oligopeptide repeats (R) of the amyloidogenic N-terminal domain of Sup35NMp from R0 to R2 play a key role in protein aggregation. Their arrangement rather than just presence is critical for propagation of the strong [PSI+] prion variants. The results confirm the suitability of the proposed combination of theoretical and empirical approaches for identifying changes in the amyloid fibrils structure, which, in turn, can significantly affect both the functional stability of amyloid fibrils and their pathogenicity.Laboratorio de Investigación y Desarrollo de Bioactivo

New PNM Mutation in SUP35

A number of [PSI+]-no-more (PNM) mutations, eliminating [PSI+] prion, were previously described in SUP35. In this study, we designed and analyzed a new PNM mutation based on the parallel in-register β-structure of Sup35 prion fibrils suggested by the known experimental data. In such an arrangement, substitution of non-charged residues by charged ones may destabilize the fibril structure. We introduced Q33K/A34K amino acid substitutions into the Sup35 protein, corresponding allele was called sup35-M0. The mutagenized residues were chosen based on ArchCandy in silico prediction of high inhibitory effect on the amyloidogenic potential of Sup35. The experiments confirmed that Sup35-M0 leads to the elimination of [PSI+] with high efficiency. Our data suggested that the elimination of the [PSI+] prion is associated with the decreased aggregation properties of the protein. The new mutation can induce the prion with very low efficiency and is able to propagate only weak [PSI+] prion variants. We also showed that Sup35-M0 protein co-aggregates with the wild-type Sup35 in vivo. Moreover, our data confirmed the utility of the strategy of substitution of non-charged residues by charged ones to design new mutations to inhibit a prion formationRFBR grant 19-04-00173, RFBR grant 17-54-150002, and PRC CNRS grant PRC1524,18-34-00536, RSF grant 18-14-0005

A novel endonuclease IV post-PCR genotyping system

Here we describe a novel endonuclease IV (Endo IV) based assay utilizing a substrate that mimics the abasic lesions that normally occur in double-stranded DNA. The three component substrate is characterized by single-stranded DNA target, an oligonucleotide probe, separated from a helper oligonucleotide by a one base gap. The oligonucleotide probe contains a non-fluorescent quencher at the 5′ end and fluorophore attached to the 3′ end through a special rigid linker. Fluorescence of the oligonucleotide probe is efficiently quenched by the interaction of terminal dye and quencher when not hybridized. Upon hybridization of the oligonucleotide probe and helper probe to their complementary target, the phosphodiester linkage between the rigid linker and the 3′ end of the probe is efficiently cleaved, generating a fluorescent signal. In this study, the use of the Endo IV assay as a post-PCR amplification detection system is demonstrated. High sensitivity and specificity are illustrated using single nucleotide polymorphism detection

The first experience of a hybrid approach in the surgical treatment of atrial fibrillation

Background: Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and is associated with an increased risk of death, progression of heart failure, and the development of cardiogenic thromboemboli. Despite the significant success in the management of AF in the paroxysmal form, the results of the treatment for patients with persistent forms of AF remain unsatisfactory. Though the surgical approach provides higher rates of efficiency regarding the restoration of a sinus rhythm, transmural lesions are not always attainable, as a result, the rate of AF recurrence in the long-term period remains fairly high. It is also impossible to create ablative patterns to the mitral and tricuspid valves during thoracoscopic epicardial ablation, which can cause the development of recurrent AF, perimitral and typical atrial flutter. Therefore, the development of hybrid approaches combining the advantages of catheter and thoracoscopic techniques is an urgent task of contemporary surgical and interventional arrhythmology. Aims: to estimate the immediate results of a hybrid approach in the management of patients with persistent AF. Methods: We report the first experience of a hybrid treatment of patients with persistent AF. 6 patients aged 53-64 years (1 female, 5 males) were included in the study. At the first stage, thoracoscopic epicardial bipolar ablation was performed (modified GALAXY protocol); the second stage (in 3 to 6 months after the thoracoscopic stage) included an intracardiac electrophysiological study with three-dimensional endocardial mapping followed by endocardial ablation. Results: The thoracoscopic stage of the hybrid treatment included ablation according to the box lesion scheme using a bipolar irrigation equipment. No lethal outcomes and severe, life-threatening complications were registered. The duration of the inpatient period was 510 hospital-days. The 2nd stage of the hybrid treatment was limited to intracardiac electrophysiological examination only in 2 patients. In 4 patients, epicardial radiofrequency ablation was complemented by endocardial radiofrequency exposure. In 3 of the 4 patients who underwent endocardial radiofrequency ablation, catheter ablation of the mitral and cavotricuspid isthmus was required because of the induction of perimitral and typical flutter, respectively. After the 2nd stage of the hybrid treatment, at the time of discharge all the patients maintained a stable sinus rhythm. There were no severe complications or lethal outcomes. Conclusion: a hybrid approach in the AF management is a safe and effective method of treatment, which combines the advantages of minimally invasive surgery and endocardial intervention in patients with persistent AF. The technique is safe and has acceptable short-term results

Фенольные соединения этанольных извлечений Lemna minor L., Lemna trisulca L. и Lemna polyrrhiza L. Schleid. и их иммуномодулирующая активность

The purpose of the study is to determine the composition of the phenolic compounds of ethanol extracts isolated from three species of duckweed: Lemna minor L., Lemna trisulca L. and Lemna polyrrhiza L. (the synonym is Spirodella polyrrhiza Schleid.) and to study its effect on immune system activation.Materials and methods. The objects of the study are: air-dried grass samples of Lemna minor L., Lemna trisuica L. and Lemna polyrrhiza L. collected during their growing season in 2010–2011 in low-flow and stagnant ponds of Kozhevnikovsky and Tomsk districts of Tomsk region. Isolation of polyphenolic complexes (PFC) was carried out by extraction of air-dried raw material with ethyl alcohol. In qualitative and quantitative analysis of the samples studied the method of reversed-phase high-performance liquid chromatography on an Agilent 1100 Series instrument (USA) was used in isocratic mode. In the experiments, 200 male C57BL / 6 and BALB / C mice aged 8–12 weeks were used to determine immunomodulatory activity. Cell proliferation was assessed by a colorimetric method. The absorption of the obtained solutions was measured with a multi-channel spectrophotometer at the wavelength of 540 nm. The determination of antibody-forming cells in the spleen was performed by local hemolysis. The titer of antibodies in serum was evaluated in the hemagglutination reaction. The local hypersensitivity reaction of immediate type was assessed by the author’s modification.Results. For the first time the study of the qualitative composition and quantitative content of PFC of Lemna minor L. (LM) , Lemna trisulca L. (LT) trisulkas, and Lemna polyrrhiza L. (LP) : (4,7 ± 0,4)%, (3,3 ± 0,3)%, (12,8 ± 0,7)% was carried out. The highest content of phenolic acids (10,76%) and the sum of flavonoids, isoflavonoids and coumarins (14,7%) were found in the LP sample. The content of chlorogenic and 3,5-dihydroxybenzoic acids was 2–9 times higher in LP than in other species of duckweed. In LM and LT with concentrations of 5 μg/ml and LP in the range of 0,5–160 μg/ml did not have a toxic effect on antigen presenting cells. When incubated with LT (20 μg/ml), the proliferation of macrophages was reduced by 1,2 times, and when incubated with LM and LT (80 μg/ml), by 1,2 and 1,8 times, respectively. PFC duckweed (LP) did not have a similar effect. LM and LP had a stimulating effect on the production of nitrites in the concentrations of 5 and 20 μg/ml, increasing it by 1,3–1,6 times. Course introduction of LT and LP led to a significant decrease in the number of antibody-forming cells by 1,5 and 2,3 times and a decrease in the local hypersensitivity reaction by 1,9 and 1,5 times, respectively.Цель исследования. Определение состава фенольных соединений этанольных извлечений, выделенных из трех видов ряски: ряски малой (Lemna minor L.), ряски тройчатой (Lemna trisulca L.) и ряски многокорневой (Lemna polyrrhiza L., синоним Spirodella polyrrhiza L.) Schleid.), и изучение его влияния на активацию системы иммунитета.Материал и методы. Объект исследования: воздушно-сухие образцы травы ряски малой (Lemna minor L.), ряски тройчатой (Lemna trisuica L.) и ряски многокорневой (Lemna polyrrhiza L.), собранные в период их вегетации в 2010–2011 гг. в малопроточных и стоячих водоемах Кожевниковского и Томского районов Томской области. Выделение полифенольных комплексов (ПФК) проводили экстракцией воздушно-сухого сырья спиртом этиловым. При качественном и количественном анализе исследуемых образцов применяли метод обращенно-фазовой высокоэффективной жидкостной хроматографии на приборе Agilent 1100 Series (США) в изократическом режиме. В экспериментах для определения иммуномодулирующей активности использовали 200 самцов мышей линий С57ВL/6 и BALB/C в возрасте 8–12 нед. Пролиферацию клеток оценивали колориметрическим методом. Абсорбцию полученных растворов замеряли при помощи многоканального спектрофотометра при длине волны 540 нм. Определение антителообразующих клеток в селезенке проводили методом локального гемолиза. Титр антител в сыворотке крови оценивали в реакции гемагглютинации. Локальную реакцию гиперчувствительности немедленного типа оценивали по методике в авторской модификации.Результаты. Впервые проведено исследование качественного состава и количественного содержания ПФК ряски малой Lemna minor L. (LM), ряски трисульки Lemna trisulca L. (LT) и ряски многокорневой Lemna polyrrhiza L.(LP): (4,7 ± 0,4)%, (3,3 ± 0,3)%, (12,8 ± 0,7)% соответственно. Наибольшее содержание фенолокислот (10,76%) и суммы флавоноидов, изофлавоноидов и кумаринов (14,7%) обнаружено в образце LP. Содержание хлорогеновой и 3,5-дигидроксибензойной кислот в 2–9 раз больше в LP, чем других видах ряски. LM, LT в концентрации 5 мкг/мл и LP в диапазоне 0,5–160 мкг/мл не оказывают токсического действия на антигенпрезентирующие клетки. При инкубации с LT (20 мкг/мл) пролиферация макрофагов снижается в 1,2 раза, а при инкубации с LM и LT (80 мкг/мл) в 1,2 и 1,8 раза соответственно. ПФК ряски многокорневой (LP) не оказывают подобного эффекта. LM и LP оказывают стимулирующее действие на продукцию нитритов в концентрациях 5 и 20 мкг/мл, усиливая ее в 1,3–1,6 раза. Курсовое введение LT и LP приводит к достоверному снижению числа антителобразующих клеток в 1,5 и 2,3 раза и уменьшению величины локальной реакции гиперчувствительности в 1,9 и 1,5 раза соответственно

Improved functionalization of oleic acid-coated iron oxide nanoparticles for biomedical applications

Superparamagnetic iron oxide nanoparticles can providemultiple benefits for biomedical applications in aqueous environments such asmagnetic separation or magnetic resonance imaging. To increase the colloidal stability and allow subsequent reactions, the introduction of hydrophilic functional groups onto the particles’ surface is essential. During this process, the original coating is exchanged by preferably covalently bonded ligands such as trialkoxysilanes. The duration of the silane exchange reaction, which commonly takes more than 24 h, is an important drawback for this approach. In this paper, we present a novel method, which introduces ultrasonication as an energy source to dramatically accelerate this process, resulting in high-quality waterdispersible nanoparticles around 10 nmin size. To prove the generic character, different functional groups were introduced on the surface including polyethylene glycol chains, carboxylic acid, amine, and thiol groups. Their colloidal stability in various aqueous buffer solutions as well as human plasma and serum was investigated to allow implementation in biomedical and sensing applications.status: publishe