Structure of KOH-soluble polysaccharides from сoniferous greens of Norway spruce (Picea abies): The pectin-xylan-AGPs complex. Part 1.

Using 7 % KOH, the polysaccharide PAK has been isolated from the coniferous greens of Norway spruce. PAK was found to contain predominantly arabinoglucuronoxylan, xyloglucan and arabinan, but also pectic polysaccharides, glucomannan and arabinogalactan proteins (AGPs), as determined by 1D/2D NMR analysis. It was found that fractionation of PAK on DEAE-cellulose resulted in simultaneous elution of pectins, arabinoglucuronoxylans and AGPs. It was evident that the content of 4-OMe-α-D-GlcpA and xylose, 1,4-ß-D-GlcpA, and T-ß-D-GlcpA increased with an increase in NaCl concentration. However, 1,4-α-D-GalpA content was almost independent of NaCl concentration, indicating unchanged pectic polysaccharide concentration. Interestingly, pectins extracted with 0.1-0.3 M NaCl solutions were richer in rhamnogalacturonan-I (RG-I) than those extracted with water and 0.01 M NaCl. Conclusion: The content of RG-I, AGPs and arabinoglucuronoxylan rises with rising NaCl concentration. An intense signal indicating an intermolecular linkage between the xylan and RG-I domains, i.e. that part of the arabinoglucuronoxylan is covalently bound to RG-I, is observed in the HMBC spectra of the polysaccharides obtained. The discovery here of a new relationship between rhamnogalacturonan I and xylan contradicts the prevailing cell wall model.

Structure of KOH-soluble polysaccharides from сoniferous greens of Norway spruce (Picea abies): The pectin-xylan-AGPs complex. Part 2.

Polymers containing arabinoglucuronoxylan, fucogalactoxyglucan, pectin and arabinogalactan proteins were obtained from PAK isolated from Norway spruce with 7 % KOH. The pectin core of PAK-I2-F-1 and PAK-I2-F-2 was dominated by RG-I, as treatment with 1,4-α-D-polygalacturonase resulted in almost complete removal of homogalacturonan. Interestingly, the above has not affected the co-fractionation of arabinoglucuronoxylan (AGX), arabinogalactan proteins and rhamnogalacturonan I (RG-I). Since pectin was mainly represented by RG-I, we concluded that xylan is specifically associated with RG-I. Correlations in the HMBC spectrum demonstrate intermolecular interactions between the α-L-Rhap (RG-I) and the Xyl (xylan), indicating a covalently bound AGX:RG-I complex via the Xyl-(1→4)-Rha bond: …→2)-[(2,4-ß-D-Xylp)-(1→4)]-[(α-D-GalpA-(1→2)]-α-L-Rhap-(1→4)-α-D-GalpA-(1→…. In PAK-H1-1-F-1 and PAK-H1-1-F-2, parts of RG-I and xylan were removed by enzymolysis. Part of the xylan was probably attached to the above-mentioned RG-I blocks. The removal of part of RG-I, xylan and the disappearance of the signal in the HMBC spectrum indicating the bond between RG-I and xylan confirms that part of the arabinoglucuronoxylan is covalently bound to RG-I. The observed glycosidic linkage contradicts the dominant PCW model in which pectin and hemicellulose polysaccharide networks are considered as independent components. It can be concluded that alkali-soluble xylan from Norway spruce was detected both in the free state and covalently bound to pectin.

Photodynamic inactivation of bacteria: Why it is not enough to excite a photosensitizer.

BACKGROUND: The development of multidrug resistance (MDR) in infectious agents is one of the most serious global problems facing humanity. Antimicrobial photodynamic therapy (APDT) shows encouraging results in the fight against MDR pathogens, including those in biofilms. METHODS: Photosensitizers (PS), monocationic methylene blue, polycationic and polyanionic derivatives of phthalocyanines, electroneutral and polycationic derivatives of bacteriochlorin were used to study photodynamic inactivation of Gram-positive and Gram-negative planktonic bacteria and biofilms under LED irradiation. Zeta potential measurements, confocal fluorescence imaging, and coarse-grained modeling were used to evaluate the interactions of PS with bacteria. PS aggregation and photobleaching were studied using absorption and fluorescence spectroscopy. RESULTS: The main approaches to ensure high efficiency of bacteria photosensitization are analyzed. CONCLUSIONS: PS must maintain a delicate balance between binding to exocellular and external structures of bacterial cells and penetration through the cell wall so as not to get stuck on the way to photooxidation-sensitive structures of the bacterial cell.

Photodynamic therapy of lung cancer with photosensitizers based on polycationic derivatives of synthetic bacteriochlorin (experimental study).

BACKGROUND: One of the tasks of anticancer photodynamic therapy is increasing the efficacy of treatment of cancer nodes with large (clinically relevant) sizes using near-infrared photosensitizers (PS). METHODS: The anticancer efficacy and mechanisms of the photodynamic action of PS based on polycationic derivatives of synthetic bacteriochlorin against Lewis lung carcinoma were studied in vitro and in vivo. RESULTS: It was found that studied PS have high phototoxicity against Lewis lung carcinoma cells: the IC50 values were about 0.8 µM for tetracationic PS and 0.5 µM for octacationic PS. In vivo studies have shown that these PS provide effective inhibition of the tumor growth with an increase in the lifespan of mice in the group by more than 130%, and more than 50% survival of mice in the group. CONCLUSIONS: Photosensitizers based on polycationic derivatives of synthetic bacteriochlorin have high photodynamic efficacy caused by the induction of necrosis and apoptosis of cancer cells, including cancer stem cells, and a sharp decrease of mitotic and proliferative activity. Studied polycationic photosensitizers are much more effective at destroying cancer stem cells and newly formed cancer vessels in comparison with anionic photosensitizers, and ensure the cessation of tumor blood flow without hemorrhages and thrombosis.

Genetic Obesity in Pregnant Ay Mice Does Not Affect Susceptibility to Obesity and Food Choice in Offspring.

Maternal diet and obesity (MO) may influence taste preferences and increase the susceptibility to obesity in offspring, but the impact of MO per se to these influences is poorly understood. We evaluated the influence of MO on food choice and susceptibility to obesity in offspring when mothers consumed a standard diet (SD). Mice with the Lethal yellow mutation (Ay/a) develop obesity consuming an SD. Metabolic parameters were assessed in pregnant and lactating Ay/a (obesity) and a/a (control) mothers. Metabolic response to the consumption of a sweet-fat diet (SFD: SD, lard, and sweet biscuits) and the choice of components of this diet were evaluated in their male and female offspring. Compared to control mothers, pregnant obese mothers had higher levels of insulin, leptin, and FGF21. MO increased food intake and liver expression of lipogenesis genes in male offspring consuming the SD. SFD consumption caused obesity development and insulin resistance, increased liver expression of glycolytic and lipogenesis genes, and affected hypothalamic expression of anorexigenic and orexigenic genes. In offspring of both sexes, MO had no effect on food choice and metabolic response to SFD intake. Therefore, when obese mothers consume a balanced diet, MO does not affect food choice and development of diet-induced obesity in offspring.

Deformation Behavior of Single Carbon Fibers Impregnated with Polysulfone by Polymer Solution Method.

Tensile deformation behavior of continuous high-strength and high-modulus single carbon fibers impregnated with a polysulfone solution was investigated. The effect of the carbon fiber type, mass fraction of the polymer, and the loading rate on the tensile strength was studied. It was observed that, whereas for high-modulus carbon fibers the magnitude of tensile strength depends significantly on the loading rate, for high-strength carbon fibers, such dependence was nearly not observed. SEM study shows that at low loading rates, elementary filaments inside the impregnated fiber are able to align themselves along the load application axis because a thermoplastic matrix can flow under the tensile stresses' force. As a result, the fiber's strength properties can be realized more effectively in the thermoplastic-based composites than in the same composite with an epoxy matrix.

Antitumor activity of photodynamic therapy with tetracationic derivative of synthetic bacteriochlorin in spheroid culture of liver and colon cancer cells.

Efficient screening of photosensitizers (PS) as well as studying their photodynamic activity, especially PS excited in the near-infrared region, require informative in vitro models to adequately reflect the architecture, thickness, and intercellular interactions in tumors. In our study, we used spheroids formed from human colon cancer HCT-116 cells and liver cancer Huh7 cells to assess the phototoxicity of a new PS based on tetracationic derivative of synthetic bacteriochlorin (BC4). We optimized conditions for the irradiation regime based on the kinetics of BC4 accumulation in spheroids and kinetics of spheroid growth. Although PS accumulated more efficiently in HCT-116 cells, characterized by more aggressive growth and high proliferative potential, they were less susceptible to the photodynamic therapy (PDT) compared to the slower growing Huh7 cells. We also showed that 3D models of spheroids were less sensitive to BC4 than conventional 2D cultures with relatively identical kinetics of drug accumulation. Our findings suggest that BC4 is a perspective agent for photodynamic therapy against cancer cells.

On the mechanisms of photodynamic action of photosensitizers based on polycationic derivatives of synthetic bacteriochlorin against human lung cancer cells A549 (in vitro study).

BACKGROUND: One of the tasks of anticancer photodynamic therapy is increasing the efficacy of treatment of cancer nodes with large (clinically relevant) sizes using near-infrared photosensitizers (PS). We study the photodynamic action against A549 human lung cancer cells using PS based on polycationic derivatives of synthetic bacteriochlorin. METHODS: The efficacy and mechanisms of the photodynamic action of PS based on polycationic derivatives of synthetic bacteriochlorin against A549 lung cancer cells were studied in vitro using immunocytochemical and morphological methods. RESULTS: It was found that PS based on tetracationic and octacationic derivatives of synthetic bacteriochlorin induce necrosis, apoptosis, decreasing of proliferative and mitotic activity, as well as reducing the number of ALDH1-positive cancer cells with signs of stem cells in A549 human lung cancer cell culture. The IC50 values (concentration of a PS that reduces cells survival by 50%) were about 0.69 µM for tetracationic PS and 0.57 µM for octacationic PS under irradiation at 30 J/cm2 while in the "dark" control they were higher than 100 µM for both PSs. CONCLUSIONS: Photosensitizers based on polycationic derivatives of synthetic bacteriochlorin have high phototoxicity against A549 cancer cells caused by the induction of necrosis and apoptosis of cancer cells, including cells with signs of stemness, and a sharp decrease of mitotic and proliferative activity.

Covalently linked pectin-arabinoglucuronoxylan complex from Siberian fir Abies sibirica Ledeb.

In this study, by NMR spectroscopy, first was proved that the pectic polysaccharides of Abies sibirica are covalently bound to arabinoglucuronoxylan (AGX). Namely, AGX is attached at the 4th position to the 1,2,4-α-L-Rha residues of the RG-I main chain, indicating the following fragment: …→2)-[(2,4-ß-D-Xylp)-(1→4)]-[(α-D-GalpA-(1→2)]-α-L-Rhap-(1→4)-α-D-GalpA-(1→…. We present direct evidence of covalent attachment between C1 of 1,2,4-ß-D-Xylp from arabinoglucuronoxylan and С4 of 1,2,4-α-L-Rhap from RG-I of pectin by detailed 2D NMR analyses. It can be concluded that the 1,2,4-α-L-Rhap residues, were substituted at the 4th position by 1,5-α-L-arabinan or 1,4-ß-D-galactan or AGX. The discovery of this interglycosidic linkage between xylan and pectin contradicts the classical model of the cell wall, which describes networks of binding glycans and pectic polysaccharides as separate and independent of one another. We can conclude that pectin undoubtedly plays a more important supporting and cross-linking role in the cell wall than is commonly thought.

Structure of KOH-extractable polysaccharides of tree greenery of from Siberian fir Abies sibirica Ledeb.

Polysaccharide ASK was extracted with aqueous KOH from the Abies sibirica foliage. Pectin, xylan, AGPs and xyloglucan were isolated from ASK by anion-exchange chromatography and Smith degradation, combined with enzymatic cleavage. Potential interactions between those polymers were examined. Since xylan, AGPs, RG-I and glucan were co-fractionated following complete removal of galacturonan (HG) with polygalacturonase, it can be inferred that the enzymatic cleavage of HG did not affect co-fractionation of cross-linking glycans, RG-I and AGPs. These were hypothesized to be bound via a covalent cross-link, as the removal of HG regions did not affect this complex. Given that pectin was represented solely by RG-I regions, it can be assumed that some of glucan, xylan and AGPs were associated directly with RG-I. Besides, the enzymatic hydrolysis eliminated most of xylose and rhamnose. This suggests implicitly that some of xylan was linked to RG-I.

The role of psychologists in international migration research: Complementing other expertise and an interdisciplinary way forward.

This research note addresses the current and potential future role of psychologists in the study of international migration. We review ways in which psychologists have contributed to the study of migration, as well as ways in which psychological scholarship could be integrated with work from other social science fields. Broadly, we discuss four major contributions that psychology brings to the study of international migration-studying migrants' internal psychological experiences, incorporating a developmental perspective, conducting experimental studies, and integrating across levels of analysis. Given the position of psychology as a 'hub science' connecting more traditional social sciences with health and medical sciences, we argue for a more prominent role for psychologists within the study of international migration. Such a role is intended to complement the roles of other social scientists and to create a more interdisciplinary way forward for the field of migration studies. The research note concludes with an agenda for further scholarship on migration.

Fibroblast Growth Factor 21 (FGF21) Administration Sex-Specifically Affects Blood Insulin Levels and Liver Steatosis in Obese Ay Mice.

FGF21 is a promising candidate for treating obesity, diabetes, and NAFLD; however, some of its pharmacological effects are sex-specific in mice with the Ay mutation that evokes melanocortin receptor 4 blockade, obesity, and hepatosteatosis. This suggests that the ability of FGF21 to correct melanocortin obesity may depend on sex. This study compares FGF21 action on food intake, locomotor activity, gene expression, metabolic characteristics, and liver state in obese Ay males and females. Ay mice were administered FGF21 for seven days, and metabolic parameters and gene expression in different tissues were assessed. Placebo-treated females were more obese than males and had lower levels of blood insulin and liver triglycerides, and higher expression of genes for insulin signaling in the liver, white adipose tissue (WAT) and muscles, and pro-inflammatory cytokines in the liver. FGF21 administration did not affect body weight, and increased food intake, locomotor activity, expression of Fgf21 and Ucp1 in brown fat and genes related to lipolysis and insulin action in WAT regardless of sex; however, it decreased hyperinsulinemia and hepatic lipid accumulation and increased muscle expression of Cpt1 and Irs1 only in males. Thus, FGF21's beneficial effects on metabolic disorders associated with melanocortin obesity are more pronounced in males.

The Same Metabolic Response to FGF21 Administration in Male and Female Obese Mice Is Accompanied by Sex-Specific Changes in Adipose Tissue Gene Expression.

The preference for high-calorie foods depends on sex and contributes to obesity development. Fibroblast growth factor 21 (FGF21) beneficially affects taste preferences and obesity, but its action has mainly been studied in males. The aim of this study was to compare the effects of FGF21 on food preferences and glucose and lipid metabolism in C57Bl/6J male and female mice with diet-induced obesity. Mice were injected with FGF21 or vehicle for 7 days. Body weight, choice between standard (SD) and high-fat (HFD) diets, blood parameters, and gene expression in white (WAT) and brown (BAT) adipose tissues, liver, muscles, and the hypothalamus were assessed. Compared to males, females had a greater preference for HFD; less WAT; lower levels of cholesterol, glucose, and insulin; and higher expression of Fgf21, Insr, Ppara, Pgc1, Acca and Accb in the liver and Dio2 in BAT. FGF21 administration decreased adiposity; blood levels of cholesterol, glucose, and insulin; hypothalamic Agrp expression, increased SD intake, decreased HFD intake independently of sex, and increased WAT expression of Pparg, Lpl and Lipe only in females. Thus, FGF21 administration beneficially affected mice of both sexes despite obesity-associated sex differences in metabolic characteristics, and it induced female-specific activation of gene expression in WAT.

Chemical composition of groundwater used for drinking in conditions of natural deficiency of iodine and selenium and evaluation of its health effect: the case of Bryansk region (Russia).

Chemical composition of drinking water was examined in rural settlements of Bryansk region to reveal its influence on distribution of endemic thyroid diseases among population after the Chernobyl accident (1986) with due regard to different sources of water, the age and composition of water-bearing rocks. Groundwater samples (n = 515 in total) were collected in 156 rural settlements over the region in the period from 2007 to 2017 and analyzed for major cationogenic elements (Ca, Mg, Sr, K, Na, Mn, Zn, Fe, Al, Si) and anions (HCO32-, Cl-, F-, SO42-, NO32-, PO42-) as well as for I- and Se using ICP-AES, potentiometry, photometry and spectrofluorimetry. The results confirmed a low supply of water samples with iodine (Median (Me) = 5.96 µg/L, variation range 0.06-41.2 µg/L) and selenium (Me = 0.18 µg/L, variation 0.001-6.21 µg/L). The concentration levels of iron (64% of examined districts), manganese (36% of examined districts) and strontium (8% of examined districts) appeared to be inconsistent with hygienic standards. The data on chemical composition of drinking water were analyzed for correlation with the medical data on the prevalence of endemic thyroid diseases among the population living in the corresponding rural settlements. Tendencies of relationship between water iodine concentration and the incidence of thyroid diseases caused by iodine deficiency among teenagers aged 8 to 12 have been found. The same trend was found when comparing geochemical data with iodine content in renal excretion in this age group. The influence of some other components of natural waters on the manifestation of thyroid insufficiency has been cartographically assessed.

Experimental investigation of optically controlled topological transition in bismuth-mica structure.

The hyperbolic materials are strongly anisotropic media with a permittivity/permeability tensor having diagonal components of different sign. They combine the properties of dielectric and metal-like media and are described with hyperbolic isofrequency surfaces in wave-vector space. Such media may support unusual effects like negative refraction, near-field radiation enhancement and nanoscale light confinement. They were demonstrated mainly for microwave and infrared frequency ranges on the basis of metamaterials and natural anisotropic materials correspondingly. For the terahertz region, the tunable hyperbolic media were demonstrated only theoretically. This paper is dedicated to the first experimental demonstration of an optically tunable terahertz hyperbolic medium in 0.2-1.0 THz frequency range. The negative phase shift of a THz wave transmitted through the structure consisting of 40 nm (in relation to THz wave transmitted through substrate) to 120 nm bismuth film (in relation to both THz waves transmitted through substrate and air) on 21 µm mica substrate is shown. The optical switching of topological transition between elliptic and hyperbolic isofrequency contours is demonstrated for the effective structure consisting of 40 nm Bi on mica. For the case of 120 nm Bi on mica, the effective permittivity is only hyperbolic in the studied range. It is shown that the in-plane component of the effective permittivity tensor may be positive or negative depending on the frequency of THz radiation and continuous-wave optical pumping power (with a wavelength of 980 nm), while the orthogonal one is always positive. The proposed optically tunable structure may be useful for application in various fields of the modern terahertz photonics.

Characterization of pectin-xylan-glucan-arabinogalactan proteins complex from Siberian fir Abies sibirica Ledeb.

Polysaccharide ASK was isolated from the Abies sibirica foliage by extraction with an aqueous KOH solution. ASK was shown to contain structurally different polymers such as arabinoglucuronoxylans, xyloglucans, glucomannans, arabinogalactan-proteins (AGPs). The pectic polysaccharides were also found in the alkaline extract of ASK and were represented by regions of homogalactorunan and rhamnogalactouronan-I whose side sugar chains were made up chiefly of highly branched 1,5-α-l-arabinan. The potential couplings between those polysaccharides were examined. Our studies showed simultaneous elution of pectin, xyloglucans, arabinoglucuronoxylans and AGPs, indicating that pectins can be covalently bound to the other cell-wall polysaccharides. NMR spectroscopy results revealed that the polysaccharides obtained by ion-exchange chromatography almost had no free reducing ends. These findings corroborate the conclusion that pectin, AGPs, glucan and xylan are bound together. The existence of the covalently bound complex of pectin-xylan-xyloglucan-AGP is suggested herein. Pectin and xylan are hypothesized to be covalently linked through RG-I regions.

Airborne chemical pollution and children's asthma incidence rate in Minsk.

Introduction: Asthma manifestations are closely connected with air pollution. Discovering interconnection between concentrations of air pollutants and asthma incidence rate among children provides information for developing effective measures to reduce air pollution and improve population health. Study purpose was to carry out hygienic analysis of the influence of atmospheric air quality on the incidence rate of bronchial asthma of children in Minsk in 2009-2018. Methods: During 2019 retrospective health cohort study was conducted, data from stationary air quality monitoring posts were collected. Correlation analysis was conducted by determining the Pearson coefficient. Results: Ten-year levels of asthma incidence rate had a moderate downward trend; the highest levels were registered among 5-9-year-old children. 74.7% of all cases of asthma were registered among children under 10 years: 33,61% among 1-4-year-old and 41.09% - among 5-9-year-old. Results of the study showed that concentrations of ammonia, particulate matter (dust/aerosol undifferentiated in composition) and lead in Minsk were characterized by downward trend, carbon oxide and nitrogen dioxide concentrations remained unstable, elevated levels of formaldehyde remained near highways with heavy traffic. Strong evidence was found for concentrations of particulate matter (dust/aerosol undifferentiated in composition) (R = 0.76-0.85, p < 0.05), lead (R = 0.69-0.97, p < 0.05), ammonia (R = 0.64-0.72, p < 0.05) nitrogen dioxide (R = 0.63-0.8, p < 0.05) and children's asthma incidence rate. Conclusions: Obtained results indicate that particulate matter, lead, ammonia and nitrogen dioxide concentrations hesitation causes changes in children's asthma incidence levels. Not being the initial cause of the disease, they influence epidemic process and can be the target for preventive measures.

Morphological Characteristics and Clinical Significance of Different Types of Tumor Vessels in Patients with Stages I-IIA of Squamous Cervical Cancer.

The determination of factors associated with progression of cervical cancer is important, both for a recurrence risk assessment and for determining optimal treatment tactics. Previously, we showed the prognostic value of different types of tumor microvessels (MVs) in gastric and breast cancer. The object of this research was to study the morphology and clinical significance of different tumor microvessels in early cervical cancer. A total of 65 archived paraffin blocks of patients with I-IIA stages of squamous cervical cancer were investigated. Samples were stained with Mayer hematoxylin and immunohistochemically using antibodies to CD34, podoplanin, HIF-1a, and Snail. The eight types of tumor MVs differed in morphology were identified. It was established that only the dilated capillaries (DСs) with weak expression of CD34, the contact type DCs, the capillaries in tumor solid component, and the lymphatic vessels in the lymphoid and polymorphic cell infiltrates of tumor stroma are associated with clinical and pathological characteristics of early cervical cancer. Preliminary results also suggest that a combination of fragmentation in tumor solid component and the contact type DCs may predict a recurrence of early cervical cancer. Given the small number of cervical cancer recurrences, the predictive significance of the described markers requires a more thorough examination.

Structural characteristics of oxalate-soluble polysaccharides from Norway spruce (Picea abies) foliage.

Structurally different polymers were derived from Picea abies foliage by successive extraction with water (PAW), HCl solution (PAA) and (NH4)2C2O4 solution (PAO). The P. abies foliage was found to contain basically low-methoxyl pectin extractable with an (NH4)2C2O4 solution. PAW was shown to comprise primarily arabinogalactan-proteins (AGPs); PAA was composed of mixed AGPs and pectic polysaccharides, with the latter prevailing; and polysaccharide PAO isolated in the highest yield included chiefly pectic polysaccharides. The major constituents of PAO were low-methoxyl and low-acetylated 1,4-α-d-galacturonan and partially acetylated RG-I. The sugar side chains of RG-I contained chiefly highly branched 1,5-α-l-arabinan and arabinogalactan type I as a minor constituent. RG-I whose side chains had 1,5-α-l-arabinan represented short regions alternating with non-acetylated and unmethylesterified galacturonan regions. In addition to pectins, polysaccharide PAO contained AGPs, xylanes and glucomannans, indicating that these polysaccharides are in an intimate interaction.