Thiacalix[4]arenes with triple bonds at the lower rim: Synthesis and structure

Reaction of thiacalixarenes with propargyl bromide in the presence of potassium or cesium carbonates leads mainly to mixture of the corresponding tetrasubstituted derivatives adopting 1,3-alternate and partial cone conformations. Sodium salts like carbonate and hydride are not effective as the base for the etherification of lower rim of thiacalix[4]- arenes by propargyl bromide. It was established that propargyl derivatives of thiacalix[4]arenes are in conformational exchange between forms due rotation of one aryl ring. © ISUCT Publishing

Langmuir monolayers and thin films of amphifilic thiacalix[4]arenes. properties and matrix for the immobilization of cytochrome c

© 2014 American Chemical Society. Formation and properties of Langmuir films of thiacalix[4]arene (TCA) derivatives containing N-donor groups on the lower rim (Y=O(CH2)3CN; OCH2CN; NH2; OCH2ArCN-p) in 1,3-alternate conformation on aqueous subphase and solid substrates have been studied. Only tetra-cyanopropoxy-p-tert-butylthiacalix[4]arene 1 forms a typical monomolecular layer with perpendicular orientation of the macrocycle relative to the water-air interface that is able to immobilize cytochrome c in the entire range of the surface pressure. Obtained monolayers were transferred by Langmuir-Schaefer technique onto quartz, indium-tin oxide (ITO), and silicon. It was demonstrated that protein activity is retained after immobilization on the substrate

Роль протеолитических систем стромы в опухолевой прогрессии (обзор)

Oncological diseases belong to life-threatening pathologies being the second most frequent cause of morbidity and mortality after cardiovascular diseases. Clarification of carcinogenesis mechanisms makes it possible to expand the stock of tools available for prevention of critical illness accompanying this pathological condition.Nowadays, proteolytic systems of tumor microenvironment (ТМЕ) are regarded as key regulators of a tumor progression including tumor growth, invasion and metastazing. The review discusses ТМЕ structure and role in cancer progression.Recent data decipher the role of proteolytic systems in the interaction stromal cells with tumor cells in different types of cancer in humans. The most known proteolytic systems contributed to cancer progression are matrix metalloproteinase system (MMP), urokinase-type plasminogen activator system (uPA-system), various cathepsins, granzymes, and elastase. Inhibition of extracellular proteolysis in the course of an oncological process is considered an effective approach to cancer therapy.Онкологические заболевания являются жизнеугрожающей патологией, занимающей второе место среди причин заболеваемости и смертности после сердечно-сосудистых заболеваний. Выяснение механизмов процесса канцерогенеза позволяет расширить арсенал средств для предупреждения развития критических состояний при этой патологии.В настоящее время протеолитические системы опухолевого микроокружения (ОМ) рассматриваются в качестве ключевых регуляторов процессов опухолевой прогрессии, обеспечивающих опухолевый рост, инвазию и метастазирование.В обзоре рассмотрены структура и роль ОМ в прогрессии опухоли. Приводятся современные данные о роли протеолитических систем во взаимодействии клеток стромы с клетками опухоли при различных типах рака человека.Наиболее изученными протеолитическими системами, вовлеченными в опухолевую прогрессию, являются система матриксных металлопротеиназ (ММП), системы активатора плазминогена урокиназного типа (uPA-система), а также различные катепсины, гранзимы и эластаза. Ингибирование внеклеточного протеолиза при развитии онкологического процесса рассматривается в качестве действенного подхода в терапии рака

Combined Use of 2-D NMR Correlation Experiments, GIAO DFT 13C Chemical Shifts and 1-D NOESY Methods in Regioisomeric and Conformational Structure Determination of Cyclophanes in Solution

The combined application of two-dimensional nuclear magnetic resonance (2-D NMR) correlation experiments and gauge-including atomic orbital (GIAO) 13C NMR chemical shift calculations allowed reliable and simple determination of regioisomeric structure of heterocyclic substituents on the calix[4]arene lower rim. Moreover, the 1-D double pulsed field gradient nuclear Overhauser effect technique allows quick and efficient measurement of small nuclear Overhauser effects and, in doing so, establishes a 3-D structure of calix[4]arene simply and unequivocally. In general, these methods may find application in the regio- and stereoisomeric structure determination of complicated macrocyclic compounds. © 2011 Springer-Verlag

Problems of Differentiation of Recurrent Glial Tumor from Necrosis by MRI Images

This paper discusses the problems of diagnosing necrosis and recurrence of glial brain tumors and ways to solve these problems

Regioselective synthesis of 1,2,3-triazolyl derivatives of calix[4]arenes based on 1,3-dipolar cycloaddition

Regioselective synthesis of 1,2,3-triazolyl derivatives of calix[4]arenes based on the 1,3-dipolar cycloaddition of substituted benzyl azides to tetra(propargyloxy)calix[4]arenes in the presence of copper iodide was carried out. The presence of the p-methoxybenzyl substituent in the triazole ring leads to a dramatic (more than tenfold) increase in the fluorescence of the corresponding macrocycle in a region of 290-310 nm. © 2013 Springer Science+Business Media New York

Does it make sense to study heart rate variability in episodes of paroxysmal atrial fibrillation during the 24-hour electrocardiographic monitoring?

Aim. To study the characteristics of heart rate variability (HRV) in episodes of paro xysmal atrial fibrillation (AF) and sinus rhythm (SR) during the 24-hour Holter electro cardiographic (ECG) monitoring and to assess the presence and nature of their relationships.Material  and  methods. We analyzed 37 records of 24-hour Holter ECG monitoring obtained from patients with paroxysmal AF. For analysis, records were selected from the Long Term Atrial Fibrillation database (LTAFDB) (n=26), as well as from the long-term storage database “Myocard-holter” of the Sverdlovsk Regional Clinical Hospital № 1 (n=11). Each record contained at least 120 min of SR and at least 120 min of paroxysmal AF episodes. In addition, 48 HRV indices were calculated independently for SR and for AF episodes, after which the 96 HRV parameters obtained for each record were subjected to exploratory data analysis.Results. Analysis of HRV in AF paroxysm showed a significant increase in the RMSSD, SD1, pNN50 indices, which confirmed the great importance of parasympathetic influence in the regulation of AF. Despite the fact that single HRV parameters in AF are not directly related to any single parameters in SR, we have shown that the AF is not completely chaotic and independent of the characteristics of baseline HR variability. We found that for some of the HRV indices determined during AF paroxysm (PAF_CVI, PAF_pNN20, PAF_pNN50, PAF_ApEn, PAF_SDNN, PAF_SD2), up to 74% of the variance of these indices can be explained using multivariate linear models, including 4 HRV indices for SR and taken as predictors. It was shown that among all the indices analyzed, only the PAF_HTI, calculated in paroxysmal AF, had a moderate negative correlation with the duration of AF episodes (r=0,60, p<0,01).Conclusion. It is shown that the study of HRV indices on AF paroxysm has a wide clinical and electrophysiological potential. The paper proposes statistical models that demonstrate the relationship between HRV in SR and in the rhythm of AF episode. The PAF_HTI index, assessed on episodes of AF, showed a relationship with the duration of AF episodes, which suggests the expediency of using HRV characteristics on AF to assess the possibility of SR recovery

Does it make sense to study heart rate variability in episodes of paroxysmal atrial fibrillation during the 24-hour electrocardiographic monitoring?

Aim. To study the characteristics of heart rate variability (HRV) in episodes of paroxysmal atrial fibrillation (AF) and sinus rhythm (SR) during the 24-hour Holter electrocardiographic (ECG) monitoring and to assess the presence and nature of their relationships. Material and methods. We analyzed 37 records of 24-hour Holter ECG monitoring obtained from patients with paroxysmal AF. For analysis, records were selected from the Long Term Atrial Fibrillation database (LTAFDB) (n=26), as well as from the long-term storage database “Myocard-holter” of the Sverdlovsk Regional Clinical Hospital № 1 (n=11). Each record contained at least 120 min of SR and at least 120 min of paroxysmal AF episodes. In addition, 48 HRV indices were calculated independently for SR and for AF episodes, after which the 96 HRV parameters obtained for each record were subjected to exploratory data analysis. Results. Analysis of HRV in AF paroxysm showed a significant increase in the RMSSD, SD1, pNN50 indices, which confirmed the great importance of para-sympathetic influence in the regulation of AF. Despite the fact that single HRV parameters in AF are not directly related to any single parameters in SR, we have shown that the AF is not completely chaotic and independent of the characteristics of baseline HR variability. We found that for some of the HRV indices determined during AF paroxysm (PAF_CVI, PAF_pNN20, PAF_pNN50, PAF_ApEn, PAF_SDNN, PAF_SD2), up to 74% of the variance of these indices can be explained using multivariate linear models, including 4 HRV indices for SR and taken as predictors. It was shown that among all the indices analyzed, only the PAF_HTI, calculated in paroxysmal AF, had a moderate negative correlation with the duration of AF episodes (r=0,60, p<0,01). Conclusion. It is shown that the study of HRV indices on AF paroxysm has a wide clinical and electrophysiological potential. The paper proposes statistical models that demonstrate the relationship between HRV in SR and in the rhythm of AF episode. The PAF_HTI index, assessed on episodes of AF, showed a relationship with the duration of AF episodes, which suggests the expediency of using HRV characteristics on AF to assess the possibility of SR recovery. © 2022, Silicea-Poligraf. All rights reserved

The Holocene environmental history of a small coastal lake on the north-eastern Kamchatka Peninsula

© 2015. A radiocarbon and tephra-dated sediment core from Lifebuoy Lake, located on the north-east coast of Kamchatka Peninsula, was analysed for pollen, spores, diatoms, chironomids and tephra in order to uncover regional environmental history. The 6500-year environmental history of Lifebuoy Lake correlates with the broad regional patterns of vegetation development and climate dynamics with both diatoms and chironomids showing near-synchronous changes. Between ca. 6300 and 3900 cal. yr. BP, the lake ecosystem was naturally enriched, with several Stephanodiscus species dominating the diatom plankton. This natural eutrophication state is likely to be due to a combination of the base-rich catchment geology, the fertilisation effect of several fires in the catchment, silica input from tephra layers and, possibly, nitrogen input from seabirds. The substantial tephra deposit at about 3850 cal. yr. BP might have stopped sedimentary phosphorus from entering the lake water thus decreasing the trophic state of the lake and facilitating the shift in diatom composition to a benthic Fragiliariaceae complex. Both diatoms and chironomids showed simultaneous compositional changes, which are also reflected by statistically significant changes in their rates of change 300-400. years after the arrival of Pinus pumila in the lake catchment. The rapid increase in both total diatom concentration and the percentage abundance of the large heavy species, Aulacoseira subarctica might be a response to the change in timing and intensity of lake spring turn-over due to the changes in the patterns of North Pacific atmospheric circulation, most notably westward shift of the Aleutian Low. The two highest peaks in A. subarctica abundance at Lifebouy Lake occurred during opposite summer temperature inferences: the earlier peak (3500-2900. cal. yr. BP) coincided with warm summers and the latter peak (300. cal. yr. BP-present) occurred during the cold summer period. These imply that A. subarctica shows no direct response to the changes of summer air temperature. Instead, it appears to thrive during the periods of increased winter precipitation, thicker ice and late spring turn-over periods, i.e., shows indirect response to climate. The clearest effect of tephra deposition on the lake ecosystem is above 908 cm (ca. 3800 cal. yr. BP) where the tephra deposit might have caused the shift from Stephanodiscus-dominated planktonic assemblages to the Fragilariaceae complex of benthic species. Tephra deposits might have also contributed towards the development of eutrophic plankton from about 6300 cal. yr. BP. It is not certain if several tephra deposits influenced diatom and chironomid changes during the last 300 years