Investigating volatile compounds in the Bacteroides secretome

Microorganisms and their hosts communicate with each other by secreting numerous components. This cross-kingdom cell-to-cell signaling involves proteins and small molecules, such as metabolites. These compounds can be secreted across the membrane via numerous transporters and may also be packaged in outer membrane vesicles (OMVs). Among the secreted components, volatile compounds (VOCs) are of particular interest, including butyrate and propionate, which have proven effects on intestinal, immune, and stem cells. Besides short fatty acids, other groups of volatile compounds can be either freely secreted or contained in OMVs. As vesicles might extend their activity far beyond the gastrointestinal tract, study of their cargo, including VOCs, is even more pertinent. This paper is devoted to the VOCs secretome of the Bacteroides genus. Although these bacteria are highly presented in the intestinal microbiota and are known to influence human physiology, their volatile secretome has been studied relatively poorly. The 16 most well-represented Bacteroides species were cultivated; their OMVs were isolated and characterized by NTA and TEM to determine particle morphology and their concentration. In order to analyze the VOCs secretome, we propose a headspace extraction with GC–MS analysis as a new tool for sample preparation and analysis of volatile compounds in culture media and isolated bacterial OMVs. A wide range of released VOCs, both previously characterized and newly described, have been revealed in media after cultivation. We identified more than 60 components of the volatile metabolome in bacterial media, including fatty acids, amino acids, and phenol derivatives, aldehydes and other components. We found active butyrate and indol producers among the analyzed Bacteroides species. For a number of Bacteroides species, OMVs have been isolated and characterized here for the first time as well as volatile compounds analysis in OMVs. We observed a completely different distribution of VOC in vesicles compared to the bacterial media for all analyzed Bacteroides species, including almost complete absence of fatty acids in vesicles. This article provides a comprehensive analysis of the VOCs secreted by Bacteroides species and explores new perspectives in the study of bacterial secretomes in relation the intercellular communication

Effect of the Mechanical and Thermal Prehistory of Precursors on the Zinc Spinel Synthesis

Исследовано накопление цинковой шпинели (ганита) обработкой реакционных смесей, состоящих из оксидов, гидроксидов, солей Zn и Al. Проанализировано влияние предварительной микроволновой обработки и механоактивации ударным и истирающим способами в планетарной и шаро-кольцевой мельницах. Установлено, что наиболее эффективный комбинированный способ, приводящий к образованию практически монофазного продукта, состоит из механической обработки смеси нитратов в планетарной мельнице и обжига в термической печиThezinc spinel (gahnite) formation by a treatment of reaction mixtures of Zn and Al oxides, hydroxides, and salts was investigated. The influence of a preliminary mechanical activation by impact (planetary mill) and attrition (ball-ring mill) action as well as a microwave treatment was analyzed. The combined method consisting of a mechanical treatment of nitrates mixture in a planetary mill and the subsequent burning in a thermal kiln was considered as the most effective as it resulted in practically single produc

Физико-химический анализ перехода байерита Al(OH)3 в γ-Al2O3

It was obtained aluminum hydroxide in the form of bayerite by precipitation with ammonia. The precipitation pH was found by the potentiometric titration. Based on the data of thermal, X‑ray diffraction and IR‑analysis it was identified the sequence of bayerite transitions up to 800 °C. The study of nitrogen adsorption- desorption allowed to determine a specific surface, a volume, and dimensions of pores for boehmite and γ- Al2O3 as 135±2 and 238±10 m2/g; 0.38 and 0.51 cm3/g; 1.7 and 3.8 nm, relatively. The value of effective activation energy for boehmite →γ- Al2O3 transition ((136±5) kJ/mol) was found by means of non- isothermal method (by Avrami equation)Получен гидроксид алюминия в виде байерита осаждением аммиаком. рН осаждения определен методом потенциометрического титрования. На основании данных термического, рентгенофазового и ИК‑спектрального анализа установлена последовательность превращений байерита в интервале температур до 800 °C. По данным адсорбции-десорбции азота для образующихся бёмита и γ-Al2O3 определена удельная поверхность, объем и средний размер пор: 135±2 и 238±10 м2/г; 0,38 и 0,51 см3/г; 1,7 и 3,8 нм соответственно. Неизотермическим методом (по уравнению Аврами) оценена эффективная энергия активации перехода байерит→бёмит: (136±5) кДж/мол

In Vivo Evaluation of PCL Vascular Grafts Implanted in Rat Abdominal Aorta

Electrospun tissue-engineered grafts made of biodegradable materials have become a perspective search field in terms of vascular replacement, and more research is required to describe their in vivo transformation. This study aimed to give a detailed observation of hemodynamic and structural properties of electrospun, monolayered poly-ε-caprolactone (PCL) grafts in an in vivo experiment using a rat aorta replacement model at 10, 30, 60 and 90 implantation days. It was shown using ultrasound diagnostic and X-ray tomography that PCL grafts maintain patency throughout the entire follow-up period, without stenosis or thrombosis. Vascular compliance, assessed by the resistance index (RI), remains at the stable level from the 10th to the 90th day. A histological study using hematoxylin-eosin (H&E), von Kossa and Russell–Movat pentachrome staining demonstrated the dynamics of tissue response to the implant. By the 10th day, an endothelial monolayer was forming on the graft luminal surface, followed by the gradual growth and compaction of the neointima up to the 90th day. The intense inflammatory cellular reaction observed on the 10th day in the thickness of the scaffold was changed by the fibroblast and myofibroblast penetration by the 30th day. The cellularity maximum was reached on the 60th day, but by the 90th day the cellularity significantly (p = 0.02) decreased. From the 60th day, in some samples, the calcium phosphate depositions were revealed at the scaffold-neointima interface. Scanning electron microscopy showed that the scaffolds retained their fibrillar structure up to the 90th day. Thus, we have shown that the advantages of PCL scaffolds are excellent endothelialization and good surgical outcome. The disadvantages include their slow biodegradation, ineffective cellularization, and risks for mineralization and intimal hyperplasia

Phytochemical Characterization, Antioxidant Activity, and Cytotoxicity of Methanolic Leaf Extract of Chlorophytum Comosum (Green Type) (Thunb.) Jacq

Chlorophytum genus has been extensively studied due to its diverse biological activities. We evaluated the methanolic extract of leaves of Chlorophytum comosum (Green type) (Thunb.) Jacques, the species that is less studied compared to C. borivilianum. The aim was to identify phytoconstituents of the methanolic extract of leaves of C. comosum and biological properties of its different fractions. Water fraction was analyzed with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Nineteen compounds belonging to different chemical classes were identified in the methanolic extract of leaves of C. comosum (Green type) (Thunb.) Jacques. In addition to several fatty acids, isoprenoid and steroid compounds were found among the most abundant constituents. One of the identified compounds, 4′-methylphenyl-1C-sulfonyl-β-d-galactoside, was not detected earlier in Chlorophytum extracts. The water fraction was toxic to HeLa cells but not to Vero cells. Our data demonstrate that methanolic extract of leaves of C. comosum can be a valuable source of bioactive constituents. The water fraction of the extract exhibited promising antitumor potential based on a high ratio of HeLa vs. Vero cytotoxicity