Asymptotic and Padé Approximants Methods in the Theory of Reinforced Plates and Shells

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The classification of the patients with pulmonary diseases using breath air samples spectral analysis

Technique of exhaled breath sampling is discussed. The procedure of wavelength auto-calibration is proposed and tested. Comparison of the experimental data with the model absorption spectra of 5% CO2 is conducted. The classification results of three study groups obtained by using support vector machine and principal component analysis methods are presented

Breath air measurement using wide-band frequency tuning IR laser photo-acoustic spectroscopy

The results of measuring of biomarkers in breath air of patients with broncho-pulmonary diseases using wide-band frequency tuning IR laser photo-acoustic spectroscopy and the methods of data mining are presented. We will discuss experimental equipment and various methods of intellectual analysis of the experimental spectra in context of above task

Tensiometric estimation of material properties of tissue spheroids

Tissue spheroids have been proposed to use as building blocks in biofabrication and as bioinks in 3D bioprinting technologies. Tissue fusion is an ubiqious phenomenon during embryonic development. Biomimetic tissue spheroid fusion is a fundamental constructional principle of emerging organ printing technology because closely placed tissue spheroids could fuse into tissue and organ-like constructs in fusion permissive bioprintable hydrogel. From physical point of view tissue spheroids could be considered as a visco-elastic-plastic soft matter or complex fluid. We hypothesize that quantitative estimation of material properties of tissue spheroids using tensiometry could predict their tissue spreading and tissue fusion behavior as well as provide a powerful insight about possible speed of post-printed tissue and organ-like constructs compaction and maturation. Tissue spheroids from human fibroblasts, ovine and human chondrocytes and immortalised human keratinocytes have been biofabricated using non-adhesive cell culture plates (Corning, USA). For estimation of material properties of tissue spheroids commercial tensiometer Microsquisher have been emploied (CellScale, Toronto, Canada). Modulus of elasticity of tissue spheroids have been calculated based on peformed tissue compression tests. In order to identify structural determinants of material properties of tissue spheroids standard perturbants of cytoskeleton such as Cytochalasin D (Sigma, USA) for disruption of microfilaments and Nocodazole (Sigma, USA) for disruption of microtubules have been used. Viability of tissue spheroids have been also estimated and their morphology have been analysed using light microscopy, histochemistry, immunohistochemistry, semithin sections stained wih toluidine blue and transmission and scanning electron microscopy. Kinetics of tissue spheroids spreading on electrospun polyurethane matrices have been analysed. Kinetics of two closely placed tissue spheroids fusion have been analysed in hanging drop. Additionally toxic effect of water solution of paramagnetic gadolinium salt (Omniscan®, GE Health Care, USA) on material properties of tissue spheroids have been investigated. It have been demonstrated that material properties of tissue spheroids biofabricated from different cell types have different modulus of elasticity. Even tissue spheroids biofabricated the same cell types but from different species have different material properties. Incubation with Cytochlasin D dramatically reduces estimated material properties of tissue spheroids. Incubation with Nocodazole does not significantly change material properties of tissue spheroids. Material properties of tissue spheroids from chondrocytes (chondrospheres) correlates very well with increasing deposition and accumulation of extracellular matrix (confirmed by expression of collagen type II and glycosoaminoglycans). The incubation with toxic concentration of gadolinium solution dramatically reduces material properties of chondrospheres. There is no any significant correlation between material properties of tissue spheriods and their spreading kinetics. However, there is a certain correction between material properties of tissue spheroids and their tissue fusion kinetics. Our data demonstrate that beside already well established role of cell adhesion receptors such as cadherin and integrins in the realisation of cell cohesion inside tissue spheroids the structural determinants of material properties of tissue spheroids also include components of cytoskeleton such as actin micofilaments and accumulated extracellular matrix. It is possible to predict post-printing tissue fusion behaviour of tissue spheroids based on preliminary estimation of their material properties. Finally, it have been also shown that material properties of tissue spheroids correlate with their viability. Thus, tensiometry is a valuable method for systematic characterization of material properties of tissue spheroids and for prediction of tissue spheroids post-printed tissue fusion behaviour

Рецидивирующая невропатия малоберцовых нервов у подростка: клиническое наблюдение

The clinical case of hereditary neuropathy with liability to pressure palsies (HNPP) confirmed the results of DNA diagnostics is described. Clinical and electrophysiological features of the course of HNPP in adolescent is analyzed. Many various illnesses require exclusion in case of the foot extensor paresis.Представлено описание клинического случая наследственной невропатии со склонностью к параличам от сдавления (ННПС), подтвержденного результатами ДНК‑диагностики. Проанализированы клинические и электрофизиологические особенности течения ННСП у подростка. Обсуждены вопросы дифференциальной диагностики различных заболеваний, проявляющихся парезом разгибателей стопы

НОВЫЙ ПОДХОД К ХРОМАТОГРАФИЧЕСКОМУ ОПРЕДЕЛЕНИЮ РАСТВОРИМОСТИ КВЕРЦЕТИНА В ВОДЕ

Significant discrepancies of literature data on the quercetin (Q) water solubility (the variations exceed 5000 times!)  at the ambient temperature prompted the elaboration of a new approach on its determination. The new approach is based not on the single measurements, but on the revealing and com­paring the two dependencies of solubility. First of them is the dependence of the solubility on pH of water solutions S(Q) = a×рН + b, followed by S(Q) interpolation on рН = 7, which corresponds to the pure water. The second one is the dependence of the solubility on acetonitrile content in acetonit­rile-water mixtures, log S(Q) = a×[CH3CN] + b, followed by log S(Q) extrapolation on the zero concentration of organic solvent, which corresponds to the pure water as well. The analysis of the solutions was fulfilled using the reversed phase high performance liquid chromatography (RP HPLC). The results obtained independently with various methods correspond well with each other: their joint average value for the few samples was 7.1 ± 1.6 mg L-1 (pS = 4.63). Since the results were obtained for quercetin samples that contained different amounts of crystalline and hydrate water, the final sub-routine of analytical procedure was their extrapolation on the zero-water content in the quercetin samples. The necessity of the preliminary control of both the water content and the organic im­pu­rities in the samples using elemental and HPLC analysis was discussed. The samples of quercetin, as well as other plant extractive substances, could contain impurities that distort the results of its water solubility.Keywords: Quercetin, water solubility, pH-dependence, dependence on concentration of organic constituent, extrapolation, HPLCDOI: http://dx.doi.org/10.15826/analitika.2019.23.3.013(Russian)1Igor G. Zenkevich, 1,2Dmitrii A. Olisov1, 2Roman V. Shafigulin, 2Andzhela V. Bulanova 1St. Petersburg State University, Institute for Chemistry, Universitetskii prosp., 26,St. Petersburg 198504, Russian Federation2Samara University; Moscow road, 34, Samara 443086, Russian FederationЗначительный разброс литературных данных по растворимости кверцетина (Q) в воде при комнатной температуре (более чем в 5000 раз!) заставляет пред­ло­жить новый подход к определению этой характеристики. Он основан не на еди­ничных определениях, а на выявлении и со­поставлении двух зависи­мостей рас­т­воримости кверцетина. Первая из них – зависимость растворимости от рН водных раство­ров, S(Q) = a×рН + b, с последующей интер­поляцией S(Q) на вели­чину рН = 7, соответствующую чистой воде. Вторая – зависимость растворимости от содержания ацетонитрила в водно-ацето­нит­ри­льных раство­рах, lg S(Q) = a×[CH3CN] + b, с экстраполяцией lg S(Q) на нулевую кон­цен­трацию органи­че­с­кого растворителя, также соответствующую чистой воде. Для анализа растворов использован метод обращенно-фазовой ВЭЖХ. Результаты, независимо определенные разными методами, согласуются между собой: их общее среднее S(Q) для не­скольких образцов равно 7.1 ± 1.6 мг/л (pS = 4.63). Поскольку полученные результаты относятся к образцам Q, содержащим различные количества кристаллизационной и гидратной воды, то заключительной стадией определений является их экст­ра­поляция на нулевое содержание воды в образцах. Обсуждается необходимость предварительного контроля содержания воды и органических примесей в образцах по данным элементного и ВЭЖХ ана­лиза. Образцы кверцетина, как и других экстрактивных веществ растений, могут содержать примеси, искажающие результаты определения растворимости.Ключевые слова: Кверцетин, растворимость в воде, зависимость от рН, зависимость от концентра­ции органического компонента раствора, экстрапо­ля­ция, высоко­эф­фек­тивная жидкост­ная хроматографияDOI: http://dx.doi.org/10.15826/analitika.2019.23.3.01

Mechanism of filopodia initiation by reorganization of a dendritic network

Afilopodium protrudes by elongation of bundled actin filaments in its core. However, the mechanism of filopodia initiation remains unknown. Using live-cell imaging with GFP-tagged proteins and correlative electron microscopy, we performed a kinetic-structural analysis of filopodial initiation in B16F1 melanoma cells. Filopodial bundles arose not by a specific nucleation event, but by reorganization of the lamellipodial dendritic network analogous to fusion of established filopodia but occurring at the level of individual filaments. Subsets of independently nucleated lamellipodial filaments elongated and gradually associated with each other at their barbed ends, leading to formation of cone-shaped structures that we term Λ-precursors. An early marker of initiation was the gradual coalescence of GFP-vasodilator-stimulated phosphoprotein (GFP-VASP) fluorescence at the leading edge into discrete foci. The GFP-VASP foci were associated with Λ-precursors, whereas Arp2/3 was not. Subsequent recruitment of fascin to the clustered barbed ends of Λ-precursors initiated filament bundling and completed formation of the nascent filopodium. We propose a convergent elongation model of filopodia initiation, stipulating that filaments within the lamellipodial dendritic network acquire privileged status by binding a set of molecules (including VASP) to their barbed ends, which protect them from capping and mediate association of barbed ends with each other