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1
SARTORI, Juliana Aparecida de Souza, Nathália Torres Corrêa MAGRI, and Claudio Lima de AGUIAR. "Clarificação de caldo de cana-de-açúcar por peróxido de hidrogênio: efeito da presença de dextrana." Brazilian Journal of Food Technology 18, no. 4 (2015): 299–306. http://dx.doi.org/10.1590/1981-6723.4215.
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Resumo A qualidade do açúcar cristal está diretamente associada à qualidade da cana-de-açúcar (Saccharum sp.) entregue nas usinas e à eficiência do processo industrial. A dextrana é considerada um parâmetro de qualidade de matéria-prima, uma vez que sua presença indica que a cana-de-açúcar sofreu deterioração entre as etapas de corte e seu processamento. Durante o processamento do caldo, a dextrana pode interferir na eficiência do processo. Na etapa de clarificação, a sulfitação tem como principal objetivo promover a redução de cor ICUMSA do caldo de cana-de-açúcar. A cor ICUMSA é o parâmetro mais importante para a classificação comercial do açúcar no Brasil e quanto mais baixo o seu valor, mais claro é o açúcar. O peróxido de hidrogênio (H2O2) tem sido estudado na clarificação do caldo de cana-de-açúcar como possível agente clarificante em substituição ao sulfito, que apresenta contra-indicações à saúde respiratória humana. Teve-se como objetivo determinar o impacto da presença de dextrana na eficiência da redução de cor ICUMSA do caldo de cana-de-açúcar por peroxidação. Durante a peroxidação, a temperatura e o pH influenciaram significativamente na redução da cor ICUMSA do caldo, sendo que o aumento da temperatura, aumento da dose de peróxido de hidrogênio e diminuição do pH levaram à diminuição da cor ICUMSA. Os valores de dextrana utilizados (até 1.000 ppm) não mostraram influência significativa na redução da cor do caldo de cana-de-açúcar, mas apresentaram interações significativas com os demais parâmetros.
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Adamski, D., and T. Michael Peters. "REVIEW OF NEARCTIC APOTOMIS HÜBNER (LEPIDOPTERA: TORTRICIDAE: OLETHREUTINI)." Canadian Entomologist 118, no. 7 (1986): 649–89. http://dx.doi.org/10.4039/ent118649-7.
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AbstractA review of Nearctic Apotomis Hübner (Lepidoptera: Tortricidae: Olethreutini) is presented. Seventeen species are recognized, of which the following are new: coloradensis, trifida, and spurinfida. Apotomis strigosa Heinrich, 1926 is considered a new synonym of tertiana McDunnough, 1922, and dextrana McDunnough, 1923 of removana Kearfott, 1907. Descriptions, distribution maps, and a key to species are provided. Illustrations of male and female genitalia and photographs of distinctive wing patterns are included. Scanning electron micrographs reveal that setae on digitus of male genitalia are taxonomically important.
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Honorato, Talita Lopes, Maria Cristiane Rabelo, Gustavo Adolfo Saavedra Pinto, and Sueli Rodrigues. "Produção de ácido lático e dextrana utilizando suco de caju como substrato." Ciência e Tecnologia de Alimentos 27, no. 2 (2007): 254–58. http://dx.doi.org/10.1590/s0101-20612007000200007.
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Huang, Ruijie, Lei Zhong, Fengwei Xie, et al. "Purification, Characterization and Degradation Performance of a Novel Dextranase from Penicillium cyclopium CICC-4022." International Journal of Molecular Sciences 20, no. 6 (2019): 1360. http://dx.doi.org/10.3390/ijms20061360.
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A novel dextranase was purified from Penicillium cyclopium CICC-4022 by ammonium sulfate fractional precipitation and gel filtration chromatography. The effects of temperature, pH and some metal ions and chemicals on dextranase activity were investigated. Subsequently, the dextranase was used to produce dextran with specific molecular mass. Weight-average molecular mass (Mw) and the ratio of weight-average molecular mass/number-average molecular mass, or polydispersity index (Mw/Mn), of dextran were measured by multiple-angle laser light scattering (MALS) combined with gel permeation chromatography (GPC). The dextranase was purified to 16.09-fold concentration; the recovery rate was 29.17%; and the specific activity reached 350.29 U/mg. Mw of the dextranase was 66 kDa, which is similar to dextranase obtained from other Penicillium species reported previously. The highest activity was observed at 55 °C and a pH of 5.0. This dextranase was identified as an endodextranase, which specifically degraded the α-1,6 glucosidic bonds of dextran. According to metal ion dependency tests, Li+, Na+ and Fe2+ were observed to effectively improve the enzymatic activity. In particular, Li+ could improve the activity to 116.28%. Furthermore, the dextranase was efficient at degrading dextran and the degradation rate can be well controlled by the dextranase activity, substrate concentration and reaction time. Thus, our results demonstrate the high potential of this dextranase from Penicillium cyclopium CICC-4022 as an efficient enzyme to produce specific clinical dextrans.
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Oropesa de la Rosa, E. "DEXTRAN TREATMENT AND ITS RHEOLOGY AT BIOETHANOL PRODUCTION PROCESS FROM MOLASSES." Revista Mexicana de Ingeniería Química 18, no. 2 (2019): 543–54. http://dx.doi.org/10.24275/uam/izt/dcbi/revmexingquim/2019v18n2/oropeza.
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Simões, Edson Azevedo, Paulo Francisco Guerreiro Cardoso, Paulo Manuel Pêgo-Fernandes, et al. "Modelo experimental de perfusão pulmonar ex vivo em ratos: avaliação histopatológica e de apoptose celular em pulmões preservados com solução de baixo potássio dextrana vs. solução histidina-triptofano-cetoglutarato." Jornal Brasileiro de Pneumologia 38, no. 4 (2012): 461–69. http://dx.doi.org/10.1590/s1806-37132012000400008.
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OBJETIVO: Comparar os achados histopatológicos e de apoptose em pulmões de ratos preservados em soluções low-potassium dextran (LPD, baixo potássio dextrana), histidine-tryptophan-ketoglutarate (HTK, histidina-triptofano-cetoglutarato) ou salina normal (SN) em 6 h e 12 h de isquemia pela utilização de um modelo experimental de perfusão pulmonar ex vivo. MÉTODOS: Sessenta ratos Wistar foram anestesiados, randomizados e submetidos à perfusão anterógrada pela artéria pulmonar com uma das soluções preservadoras. Após a extração, os blocos cardiopulmonares foram preservados por 6 ou 12 h a 4ºC, sendo então reperfundidos com sangue homólogo em um sistema de perfusão ex vivo durante 60 min. Ao final da reperfusão, fragmentos do lobo médio foram extraídos e processados para histopatologia, sendo avaliados os seguintes parâmetros: congestão, edema alveolar, hemorragia alveolar, hemorragia, infiltrado inflamatório e infiltrado intersticial. O grau de apoptose foi avaliado pelo método TdT-mediated dUTP nick end labeling. RESULTADOS: A histopatologia demonstrou que todos os pulmões preservados com SN apresentaram edema alveolar após 12 h de isquemia. Não houve diferenças em relação ao grau de apoptose nos grupos estudados. CONCLUSÕES: No presente estudo, os achados histopatológicos e de apoptose foram semelhantes com o uso das soluções LPD e HTK, enquanto a presença de edema foi significativamente maior com o uso de SN.
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Oliveira, Antonio Sérgio de, Danilo Antonio Rinaldi, Carolina Tamanini, Cristiano Elemar Voll, and Maria Celia Oliveira Hauly. "Fatores que Interferem na Produção de Dextrana por Microrganismos Contaminantes da Cana-de-Açúcar." Semina: Ciências Exatas e Tecnológicas 23, no. 1 (2002): 93. http://dx.doi.org/10.5433/1679-0375.2002v23n1p93.
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Yamamoto, Kazuya, Kenji Yoshikawa, and Shigetaka Okada. "Structure of Dextran Synthesized by Dextrin Dextranase fromAcetobacter capsulatusATCC 11894." Bioscience, Biotechnology, and Biochemistry 57, no. 9 (1993): 1450–53. http://dx.doi.org/10.1271/bbb.57.1450.
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Yamamoto, Kazuya, Kenji Yoshikawa, and Shigetaka Okada. "Dextran Synthesis from Reduced Maltooligosaccharides by Dextrin Dextranase fromAcetobacter capsulatusATCC 11894." Bioscience, Biotechnology, and Biochemistry 57, no. 1 (1993): 136–37. http://dx.doi.org/10.1271/bbb.57.136.
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Yamamoto, Kazuya, Kenji Yoshikawa, and Shigetaka Okada. "Effective dextran production from starch by dextrin dextranase with debranching enzyme." Journal of Fermentation and Bioengineering 76, no. 5 (1993): 411–13. http://dx.doi.org/10.1016/0922-338x(93)90035-7.
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Pittrof, Silke L., Larissa Kaufhold, Anja Fischer, and Daniel Wefers. "Products Released from Structurally Different Dextrans by Bacterial and Fungal Dextranases." Foods 10, no. 2 (2021): 244. http://dx.doi.org/10.3390/foods10020244.
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Dextran hydrolysis by dextranases is applied in the sugar industry and the medical sector, but it also has a high potential for use in structural analysis of dextrans. However, dextranases are produced by several organisms and thus differ in their properties. The aim of this study was to comparatively investigate the product patterns obtained from the incubation of linear as well as O3- and O4-branched dextrans with different dextranases. For this purpose, genes encoding for dextranases from Bacteroides thetaiotaomicron and Streptococcus salivarius were cloned and heterologously expressed in Escherichia coli. The two recombinant enzymes as well as two commercial dextranases from Chaetomium sp. and Penicillium sp. were subsequently used to hydrolyze structurally different dextrans. The hydrolysis products were investigated in detail by HPAEC-PAD. For dextranases from Chaetomium sp., Penicillium sp., and Bacteroides thetaiotaomicron, isomaltose was the end product of the hydrolysis from linear dextrans, whereas Penicillium sp. dextranase led to isomaltose and isomaltotetraose. In addition, the latter enzyme also catalyzed a disproportionation reaction when incubated with isomaltotriose. For O3- and O4-branched dextrans, the fungal dextranases yielded significantly different oligosaccharide patterns than the bacterial enzymes. Overall, the product patterns can be adjusted by choosing the correct enzyme as well as a defined enzyme activity.
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Montes, Everaldo Joaquin, Ramiro Torres, and Ricardo Andrade. "Aumento del punto de ebullición de soluciones modelos para jugo de caña de azúcar." Temas Agrarios 11, no. 2 (2006): 5–13. http://dx.doi.org/10.21897/rta.v11i2.640.
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Conocer la elevación del punto de ebullición en los jugos de caña de azúcar a diferentes concentraciones, es fundamental para el diseño y operación de diversos equipos para su procesamiento, en particular evaporadores de múltiple efecto. Esta fue determinada para jugo de la caña de azúcar, utilizando soluciones modelos con cuatro componentes (sacarosa, glucosa, fructosa y dextrana), medidas en un rango de concentraciones de sólidos solubles de 30 a 60 °Brix y a presiones entre 6.2 x 103 y 7.6 x 104 Pa (abs.). Los datos experimentales se representaron utilizando la regla de Dühring y la ecuación de Antoine. A 30 °Brix, el aumento en la temperatura de ebullición fue independiente de la presión la cual varió con las relaciones de los componentes de las soluciones modelos. Las desviaciones considerables de este comportamiento ocurrieron a concentraciones mayores de 30 °Brix. Los datos experimentales se ajustaron satisfactoriamente a la regla de Dühring y la ecuación de Antoine.
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Whiteside, C. I., and C. J. Lumsden. "Transglomerular cationic macromolecular flux is mediated by a convection-binding mechanism." American Journal of Physiology-Renal Physiology 256, no. 5 (1989): F882—F893. http://dx.doi.org/10.1152/ajprenal.1989.256.5.f882.
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Glomerular polyanion function was explored using charged and neutral [3H]dextrans in the multiple indicator-dilution experiment. Anesthetized dogs received an intrarenal bolus of 125I-labeled albumin (plasma reference), [14C]inulin (glomerular reference) and [3H]dextran (test solute), followed by rapid serial sampling of the renal venous and urine outflows. Reduced urinary recovery of cationic diethylaminoethyl dextrans (DEAE) [3H]dextrans [19.0– to 31.5–A Stokes-Einstein radius (SER)], compared with neutral [3H]dextran indicated intrarenal binding reversed by excess unlabeled cationic dextran. Tubular microperfusion with cationic [3H]dextran confirmed a pretubular binding site (presumed glomerular). The application of a computer-assisted mathematical model of convective flux plus reversible binding revealed that binding affinity increased with molecular size. In vitro high-affinity binding of the same cationic [3H]dextrans to isolated rat glomeruli was also found to increase with molecular size and was inhibited by protamine sulfate. Intrarenal polycation perfusion with protamine sulfate (1.0–3.8 mg/g kidney) or lysozyme (1.1–2.2 mg/g body wt) resulted in intraglomerular binding of anionic [3H]dextran without increased proteinuria or altered glomerular permselectivity to neutral [3H]dextrans less than or equal to 33.0–A SER. Hence, transglomerular cationic solute flux is mediated by a convection-binding mechanism that creates an effective polyvalent barrier.
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Barrowcliffe, M. P., G. D. Zanelli, D. Ellison, and J. G. Jones. "Clearance of charged and uncharged dextrans from normal and injured lungs." Journal of Applied Physiology 68, no. 1 (1990): 341–47. http://dx.doi.org/10.1152/jappl.1990.68.1.341.
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To examine how molecular charge affects the transfer of molecules across the alveolar-capillary barrier, we prepared the following dextrans of equivalent molecular size (mol wt 10,000) but varying molecular charge: neutral dextran, cationic DEAE dextran, and anionic dextran sulfate. These were labeled with 99mTc. The lungs of three groups of anesthetized rabbits were insufflated with dextran aerosols, with six rabbits receiving each type, and the half-time pulmonary clearance (t1/2) was measured. Control t1/2's (95% confidence limits) were 95 (74-120), 227 (192-268), and 291 (246-345) min for neutral, cationic, and anionic dextrans, respectively. One week later, when the same animals were restudied 4 h after 3 micrograms/kg iv endotoxin, t1/2's were 102 (75-139), 167 (149-187), and 126 (102-154) min, respectively. After 30 min during this repeat study, animals were ventilated with 20 breaths of cigarette smoke, which acutely increased the clearance rate to 34 (26-46), 25 (20-31), and 13 (7-24) min, respectively. Mean carboxyhemoglobin levels were not significantly different in the three groups: 13.6, 12.7, and 11.1%, respectively. These results demonstrated that neutral dextrans showed the same clearance rate before and after endotoxin, whereas the charged dextrans had a significantly faster clearance after endotoxin. After smoke exposure the anionic dextran left the lung more rapidly than the neutral dextran. Thus molecular charge affects solute transfer across the alveolar-capillary barrier in both normal and injured lungs, and an effect of endotoxin on the lung can be detected with charged dextrans but not with neutral dextran.
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Beck-Candanedo, Stephanie, David Viet, and Derek G. Gray. "Partitioning of charged and neutral dextran-dye derivatives in biphasic cellulose nanocrystal suspensions." Canadian Journal of Chemistry 86, no. 6 (2008): 503–11. http://dx.doi.org/10.1139/v08-005.
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The partitioning behaviour of dye-labeled dextrans of high molecular weight in aqueous suspensions of native cellulose nanocrystals was studied. Cellulose concentrations lie in the isotropic–nematic coexistence region. Blue dextrans of various molecular weights and degrees of substitution of dye molecules (anionic Cibacron blue 3G-A) were investigated. Increasing the total concentration of blue dextran and degree of dye substitution led to increasing partition coefficients. Increasing dextran molecular weight resulted in higher partition coefficients, in agreement with theory. Partition coefficients were larger than predicted theoretically using a second virial coefficient approximation. Electrostatic and entropic contributions to the partition coefficient of blue dextran are discussed. Dextrans labeled with neutral fluorescein isothiocyanate did not partition preferentially in this system.Key words: partition coefficient, cellulose nanocrystals, dextrans, degree of substitution, polyelectrolyte.
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Schmid, Jonas, Daniel Wefers, Rudi F. Vogel, and Frank Jakob. "Analysis of Structural and Functional Differences of Glucans Produced by the Natively Released Dextransucrase of Liquorilactobacillus hordei TMW 1.1822." Applied Biochemistry and Biotechnology 193, no. 1 (2020): 96–110. http://dx.doi.org/10.1007/s12010-020-03407-6.
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AbstractThe properties of the glucopolymer dextran are versatile and linked to its molecular size, structure, branching, and secondary structure. However, suited strategies to control and exploit the variable structures of dextrans are scarce. The aim of this study was to delineate structural and functional differences of dextrans, which were produced in buffers at different conditions using the native dextransucrase released by Liquorilactobacillus (L.) hordei TMW 1.1822. Rheological measurements revealed that dextran produced at pH 4.0 (MW = 1.1 * 108 Da) exhibited the properties of a viscoelastic fluid up to concentrations of 10% (w/v). By contrast, dextran produced at pH 5.5 (MW = 1.86 * 108 Da) was gel-forming already at 7.5% (w/v). As both dextrans exhibited comparable molecular structures, the molecular weight primarily influenced their rheological properties. The addition of maltose to the production assays caused the formation of the trisaccharide panose instead of dextran. Moreover, pre-cultures of L. hordei TMW 1.1822 grown without sucrose were substantial for recovery of higher dextran yields, since the cells stored the constitutively expressed dextransucrase intracellularly, until sucrose became available. These findings can be exploited for the controlled recovery of functionally diverse dextrans and oligosaccharides by the use of one dextransucrase type.
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Baktir, Afaf, Zumrotul Koiriyah, and Ali Rohman. "A THERMOPHILIC MICROBE PRODUCING DEXTRANASE FROM HEATED SUGAR CANE." Indonesian Journal of Chemistry 5, no. 3 (2010): 224–27. http://dx.doi.org/10.22146/ijc.21794.
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A thermophilic aerobe microorganism designated NP4, was isolated from the heated sugar cane. It grew on dextran, and produced a thermoactive extracellular dextranase. Screening and isolation was done by assay of dextranase activity semi quantitatively on solid medium containing blue dextran. It provided several colonies with different morphology exhibited decolourized zones around, on culture plates containing blue dextran 2000R. The screening resulted in isolation of one microbe which efficiently assimilate dextran as carbon source. Dextranase production from the choised strain in liquid medium was conducted at room temperature for 8 hours with shaking speed of 125 rpm. The dextranase enzyme showed optimum pH of 8 and optimum temperature of 60 oC. Keywords: thermophilic aerobe, sugar cane, dextranase activity.
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Sanders, Jonathan R., N. Adrienne Pou, and Robert J. Roselli. "Neutral and DEAE dextrans as tracers for assessing lung microvascular barrier permeability and integrity." Journal of Applied Physiology 93, no. 1 (2002): 251–62. http://dx.doi.org/10.1152/japplphysiol.00635.2000.
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Steady-state lymph-to-plasma concentration ratios (L/Ps) of neutral dextrans, cationic DEAE dextrans, and endogenous proteins were determined under normal and increased permeability conditions in six unanesthetized yearling sheep prepared with chronic lung lymph fistulas. Fluorescent dextrans with radii ranging from 1 to 30 nm were intravenously infused, and after 24 h, perilla ketone (PK) was given to alter permeability while the dextran infusion was maintained. Plasma and lymph samples were collected before and after PK administration and analyzed for dextran and protein concentrations after high-performance liquid chromatography size separation. Under both baseline and increased permeability conditions, DEAE dextrans had higher L/Ps than neutral dextrans of similar size but lower L/Ps than proteins of similar size. Comparison of L/Ps before and after PK revealed that the percentage change in permeability for neutral and DEAE dextrans was significantly larger than that for proteins. These results suggest that 1) the pulmonary microvascular barrier behaves as a net negative barrier, 2) some transport mechanisms for proteins and dextrans are different, and 3) neutral and cationic dextrans are more sensitive markers than proteins of the same size for assessing changes in pulmonary capillary permeability.
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Hijah, Vestika Iskawati Wahidul, Titi Candra Sunarti, and Anja Meryandini. "Production and Characteristics of Yeast Dextranase from Soil." HAYATI Journal of Biosciences 26, no. 1 (2019): 26. http://dx.doi.org/10.4308/hjb.26.1.26.
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The existence of dextran in sugar cane juice is a major problem in the sugar industry, causing substantial losses. Treatment of dextran through enzymatic hydrolysis using dextranase is highly recommended as the most suitable method at this time because this is more effective and more economical. This study investigated the production and characterization of dextranase from local isolate yeast to degrade dextran on sugar cane juice. The selected yeast was identified on the basis of molecular identification. Dextranase was produced from the culture with the best carbon and nitrogen sources then was characterized. Application of enzyme was also evaluated. As a selected isolate, F4 had the closest relationship with Pichia kudriavzevii. The highest production of dextranase was induced by the supplementation of glucose and combination of yeast extract and peptone. The enzyme had optimum working condition at pH 7, temperature at 30°C and it is more stable at 4°C of storage temperature. The cation Na+ played key role as co-factor while K+ and Ca2+ were detected as inhibitor of the enzyme. Dextranase from F4 isolate can hydrolyze dextran both in pure and in mixed dextran substrate, but with a lower hydrolysis rate.
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Bashir, Sajid, Peter J. Derrick, Peter Critchley, Paul J. Gates, and James Staunton. "Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry of Dextran and Dextrin Derivatives." European Journal of Mass Spectrometry 9, no. 1 (2003): 61–70. http://dx.doi.org/10.1255/ejms.510.
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Application of matrix-assisted laser desorption/ionization (MALDI) to the analysis of dextran and dextrin derivatives, specifically glucose saccharides, by time-of-flight (TOF) mass spectrometry is reported. MALDI-TOF analysis was carried out on alpha-, beta-and gamma-cyclodextrin, two O-methylated beta-cyclodextrins of differing degrees of substitution (DS) and dextrans (a linear glucose saccharide), as pure and doped solutions and as mixtures of two or more of these analytes. Doping was carried out with trace amounts of inorganic salts. The purpose of the analysis of the cyclodextrins was to determine whether they would form inclusion complexes with the various added cations, or whether less specific cation addition/exchange was occurring either prior to desorption or in the gas phase.
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Nielsen, Thorbjørn Terndrup, Catherine Amiel, Laurent Duroux та ін. "Formation of nanoparticles by cooperative inclusion between (S)-camptothecin-modified dextrans and β-cyclodextrin polymers". Beilstein Journal of Organic Chemistry 11 (21 січня 2015): 147–54. http://dx.doi.org/10.3762/bjoc.11.14.
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Novel (S)-camptothecin–dextran polymers were obtained by “click” grafting of azide-modified (S)-camptothecin and alkyne-modified dextrans. Two series based on 10 kDa and 70 kDa dextrans were prepared with a degree of substitution of (S)-camptothecin between 3.1 and 10.2%. The binding properties with β-cyclodextrin and β-cyclodextrin polymers were measured by isothermal titration calorimetry and fluorescence spectroscopy, showing no binding with β-cyclodextrin but high binding with β-cyclodextrin polymers. In aqueous solution nanoparticles were formed from association between the (S)-camptothecin–dextran polymers and the β-cyclodextrin polymers.
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Baktir, Afaf, and Kuntaman Kuntaman. "KEMAMPUAN TUMBUH Ecoli DH5 KOMPETEN DALAM 'MEDIUM MINIMAL' MENGANDUNG DEKSTRAN UNTUK MENGEMBANGKAN METODE SELEKSI KLON GEN DEKSTRANASE." Berkala Penelitian Hayati 7, no. 1 (2001): 53–59. http://dx.doi.org/10.23869/bphjbr.7.1.20017.
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Dextranase gene cloning so far have used selection method base on halo formation around he recombinant dex colony grown on LB blue dextran agar plate. The difficulty of the cloning process is in the selection of dex positive clone. As an example, for obtaining dex gene it has been screened about 36500 colonies. The reason that it was difficult to determine Dex positive clone because dextran hydrolysis by primary recombinant E. coli cells in LB blue dextran medium was too weak. In the present research, we have designed a minimal medium contained dextran and low concentration of yeast extract to reduce difficulty and to increase accuracy and reproducibility determining of recombinant dex E. coli. In this experiment, dex positive cloned was simulated by competent E.coli grown in medium contained dextranase. The minimal medium designed consist of dextran 1 percent, yeast extract 0.01 percent, KH2PO4 0.1 percent, MgSO4 0.24 percent, NaCl 0.1 percent, CaCl2 0.01 percent. this medium have proved can distinguish between recombinant E. coli dex and other E. coli ie. The competent E. coli can grow well in this medium which was supplied by dextranase, but without dextranase this competent E.coli did not or limited grow
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Juntarachot, Nucharee, Duangporn Kantachote, Sartjin Peerajan, Sasithorn Sirilun, and Chaiyavat Chaiyasut. "Optimization of Fungal Dextranase Production and Its Antibiofilm Activity, Encapsulation and Stability in Toothpaste." Molecules 25, no. 20 (2020): 4784. http://dx.doi.org/10.3390/molecules25204784.
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Dextranase catalyzes the degradation of the substrate dextran, which is a component of plaque biofilm. This enzyme is involved in antiplaque accumulation, which can prevent dental caries. The activity of crude dextranase from Penicillium roquefortii TISTR 3511 was assessed, and the maximum value (7.61 unit/g) was obtained at 37 °C and pH 6. The Plackett–Burman design was used to obtain significant factors for enhancing fungal dextranase production, and three influencing factors were found: Dextran, yeast extract concentration and inoculum age. Subsequently, the significant factors were optimized with the Box–Behnken design, and the most suitable condition for dextranase activity at 30.24 unit/g was achieved with 80 g/L dextran, 30 g/L yeast extract and five day- old inoculum. The use of 0.85% alginate beads for encapsulation exhibited maximum dextranase activity at 25.18 unit/g beads, and this activity was stable in toothpaste for three months of testing. This study explored the potential production of fungal dextranase under optimal conditions and its encapsulation using alginate for the possibility of applying encapsulated dextranase as an additive in toothpaste products for preventing dental caries.
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Hansen-Flaschen, J. H., P. N. Lanken, G. G. Pietra, P. M. Sampson, L. Johns, and A. P. Fishman. "Effect of 100% O2 on passage of uncharged dextrans from blood to lung lymph." Journal of Applied Physiology 60, no. 5 (1986): 1797–809. http://dx.doi.org/10.1152/jappl.1986.60.5.1797.
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Since charge as well as size may influence the passage of plasma proteins from blood to lung lymph, we used uncharged dextrans as tracers to study the effects of hyperoxic lung injury on the molecular sieving properties of the pulmonary microcirculation in unanesthetized sheep. Polydisperse [3H]dextran was infused intravenously into five sheep before and after the animals breathed 100% O2 until lymph flow increased threefold (66–84 h). Lymph-to-plasma concentration ratios (L/P) were determined for [3H]dextran fractions of graded molecular sizes (1.6–8.4 nm effective radius) from samples obtained during the infusions. Before hyperoxia the blood-lymph barrier was highly restrictive to transport of [3H]dextrans above 5.0 nm in radius; steady-state L/P for these molecules averaged 0.03 or less. After the sheep breathed 100% O2, [3H]dextrans as large as 8.4 nm radius appeared in the lymph. Posthyperoxia, the L/P were significantly increased relative to prehyperoxia base-line values for every [3H]dextran fraction larger than 2.0 nm radius (P less than 0.05). In contrast, neither the L/P for albumin or total protein changed significantly. At autopsy, electron microscopy showed widespread damage to the endothelium of the alveolar capillaries with infrequent gaps between endothelial cells. In two control sheep, inhalation of compressed air for 96 h had no effect on lymph flow or L/P for the [3H]dextrans. We conclude that O2 poisoning reduced the selective sieving of uncharged dextrans across the blood-lymph barrier of the lungs and allowed larger dextrans to enter the lymph. These larger molecules may have leaked from the pulmonary microcirculation via disruptions in the continuity of the endothelial lining.
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Liao, Shu Qiong, Xiao Yu Peng, Xue Wang Zhang, et al. "Research on Kinetics of Hydrolysis Preparation of Micro-Molecular Dextran." Advanced Materials Research 748 (August 2013): 295–98. http://dx.doi.org/10.4028/www.scientific.net/amr.748.295.
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Micro-molecular dextran was prepared in sub-critical water and sub-critical Water/CO2by hydrolysis of dextran20. The obtained products were mainly characterized by GPC. The kinetics of hydrolysis of dextran20 has been studied in the temperature range of 423.15K-463.15K. It was found that the level of dextran20 hydrolysis in sub-critical water and sub-critical water/CO2was first level kinetics equation. The activation energy was also calculated. The results demonstrated that the molecular weight of micro-molecular dextran could be controlled.
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Sarbini, Shahrul R., Sofia Kolida, Thierry Naeye та ін. "In VitroFermentation of Linear and α-1,2-Branched Dextrans by the Human Fecal Microbiota". Applied and Environmental Microbiology 77, № 15 (2011): 5307–15. http://dx.doi.org/10.1128/aem.02568-10.
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ABSTRACTThe role of structure and molecular weight in fermentation selectivity in linear α-1,6 dextrans and dextrans with α-1,2 branching was investigated. Fermentation by gut bacteria was determined in anaerobic, pH-controlled fecal batch cultures after 36 h. Inulin (1%, wt/vol), which is a known prebiotic, was used as a control. Samples were obtained at 0, 10, 24, and 36 h of fermentation for bacterial enumeration by fluorescentin situhybridization and short-chain fatty acid analyses. The gas production of the substrate fermentation was investigated in non-pH-controlled, fecal batch culture tubes after 36 h. Linear and branched 1-kDa dextrans produced significant increases inBifidobacteriumpopulations. The degree of α-1,2 branching did not influence theBifidobacteriumpopulations; however, α-1,2 branching increased the dietary fiber content, implying a decrease in digestibility. Other measured bacteria were unaffected by the test substrates except for theBacteroides-Prevotellagroup, the growth levels of which were increased on inulin and 6- and 70-kDa dextrans, and theFaecalibacterium prausnitziigroup, the growth levels of which were decreased on inulin and 1-kDa dextrans. A considerable increase in short-chain fatty acid concentration was measured following the fermentation of all dextrans and inulin. Gas production rates were similar among all dextrans tested but were significantly slower than that for inulin. The linear 1-kDa dextran produced lower total gas and shorter time to attain maximal gas production compared to those of the 70-kDa dextran (branched) and inulin. These findings indicate that dextrans induce a selective effect on the gut flora, short-chain fatty acids, and gas production depending on their length.
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Berthiaume, E. P., C. Medina, and J. A. Swanson. "Molecular size-fractionation during endocytosis in macrophages." Journal of Cell Biology 129, no. 4 (1995): 989–98. http://dx.doi.org/10.1083/jcb.129.4.989.
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The sorting of macromolecules within and between membranous organelles is often directed by information contained in protein primary or secondary structure. We show here that absent such structural information, macromolecules internalized by endocytosis in macrophages can be sorted by size. After endocytosis, small solute probes of fluid-phase pinocytosis were recycled to the extracellular medium more efficiently than large solutes. Using macropinosomes pulse labeled with fluorescent dextrans, we examined the ability of organelles to exchange solute contents. Dextran exchange was optimal between organelles of similar age, and small dextrans exchanged more efficiently than large dextrans. Efferent solute movement, from lysosomes or phagolysosomes toward the plasma membrane, occurred through the same endocytic vesicles as afferent movement, toward lysosomes and this movement was solute size dependent. Remarkably, uniform mixtures of different-sized dextrans delivered into lysosomes separated into distinct organelles containing only one dextran or the other. Thus, the dynamics of endosomes and lysosomes were sufficient to segregate macromolecules by size. This intracellular size fractionation could explain how, during antigen presentation, peptides generated by lysosomal proteases recycle selectively from lysosomes to endosomes for association with class II MHC molecules.
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Sahagun, G., S. A. Moore, and M. N. Hart. "Permeability of neutral vs. anionic dextrans in cultured brain microvascular endothelium." American Journal of Physiology-Heart and Circulatory Physiology 259, no. 1 (1990): H162—H166. http://dx.doi.org/10.1152/ajpheart.1990.259.1.h162.
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The luminal surface of vascular endothelium contains glycocalyx residues that establish an overall negative charge. Recent evidence has suggested that local endothelial surface charge properties may account for the permeability properties of various macromolecules. It has also been suggested that altered membrane charge on the luminal side may play a role in thrombogenesis and atherogenesis. The relationship of macromolecule charge to endothelial cell permeability was examined in vitro using mouse brain microvessel endothelial cells grown to confluence on a nitrocellulose filter separating a double-chamber system. Endothelial permeability to 4K and 10K fluorescein-labeled neutral dextrans was compared with the permeability to 4K and 10K fluorescein-labeled anionic dextrans (sulfated). After 1 h, there was significantly greater permeability of neutral fluorescein-labeled dextran than of anionic fluorescein-labeled dextran in each particle size. In addition, there was significantly greater permeability of 4K than 10K fluorescein-labeled dextrans of either charge. The findings indicate that charge in addition to size plays an important role in the movement of macromolecules across cultured microvascular endothelial cells.
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Zou, Qing Song, Yuan Yuan Pu, Su Xia Li, Qing Wang, Xiao Wang, and Shan Chen. "Ultrasonic Degradation of Dextran in Aqueous Solution." Advanced Materials Research 396-398 (November 2011): 1624–27. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.1624.
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An ultrasonic device with frequency of 20 kHz was used to investigate the effect of different operational parameters such as ultrasonic power, temperature and initial molecular weight on dextran degradation. Results show that the molecular weight of dextran can be controlled by ultrasonic treatment. Higher the ultrasonic power and lower the temperature could increase the degradation rate (R).The initial molecular weight plays an important role in at the initial stage of dextran degradation (within 20 minutes). A smilar limiting molecular weight (Mw≈8.7×104) was obtained after 2 hours ultrasonic treatment for four different initial molecular weight dextrans, suggesting that the limiting molecular weight is independent on the initial molecular weight of dextran. Ultrasonic treatment can be used as a safe, simple and effective method to control the molecular weight of dextran.
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Messetti, M. A., A. M. dos Santos, D. F. de Angelis, G. O. Chierice, and S. Claro Neto. "ESTUDO DO DERIVADO DO ÓLEO DE RICINUS COMMUNIS L. (MAMONA) COMO AGENTE BIOCIDA E REDUTOR DA VISCOSIDADE PRODUZIDA POR LEUCONOSTOC MESENTEROIDES EM INDÚSTRIAS SUCROALCOOLEIRAS." Arquivos do Instituto Biológico 77, no. 2 (2010): 301–8. http://dx.doi.org/10.1590/1808-1657v77p3012010.
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RESUMO Das sementes da mamona extrai-se o óleo de rícino, utilizado in natura ou em sua forma modificada nas áreas médica, farmacêutica e industrial. Um de seus derivados químicos - o Poliquilgerm® - evidencia propriedades antifúngicas sobre Candida albicans e bacteriostática/ bactericida sobre Escherichia coli no nível de 99,9%. Considerando-se essas propriedades, aplicouse o Poliquilgerm® em culturas de Leuconostoc mesenteroides, uma das espécies de bactéria contaminante dos mostos em indústrias sucroalcooleiras. Esta bactéria quando presente em mostos produz além do ácido láctico, a dextrana, que é um polímero da glicose que aumenta a viscosidade dos fluidos dos processos. No presente trabalho avaliou-se o efeito de diferentes concentrações do Poliquilgerm® sobre a viscosidade produzida por L. mesenteroides em diferentes meios de cultivo, condições de pH, e temperatura. Verificou-se 20,56% de diminuição da viscosidade quando se utilizou 1,0% do produto, além da inibição do crescimento da bactéria após 20 horas em contato com 1,0 e 0,2% de Poliquilgerm®. L. mesenteroides apresentou melhor crescimento em valores de pH 6,0, tanto a 28 como a 33º C, evidenciado pela maior produção de biomassa. Além disso, em meio de cultura neste pH verificou-se maior porcentagem de diminuição da viscosidade em ambas as concentrações utilizadas. Estas mesmas concentrações alcançaram até 100% de diminuição das UFC/mL após 24 horas em contato com o produto, evidenciado por quantificação da biomassa e confirmado mediante plaqueamento pela técnica “Pour Plate”.
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Kotb, Ahmed M., Tobias Müller, Jing Xie, Bela Anand-Apte, Karlhans Endlich, and Nicole Endlich. "Simultaneous assessment of glomerular filtration and barrier function in live zebrafish." American Journal of Physiology-Renal Physiology 307, no. 12 (2014): F1427—F1434. http://dx.doi.org/10.1152/ajprenal.00029.2014.
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The zebrafish pronephros is a well-established model to study glomerular development, structure, and function. A few methods have been described to evaluate glomerular barrier function in zebrafish larvae so far. However, there is a need to assess glomerular filtration as well. In the present study, we extended the available methods by simultaneously measuring the intravascular clearances of Alexa fluor 647-conjugated 10-kDa dextran and FITC-conjugated 500-kDa dextran as indicators of glomerular filtration and barrier function, respectively. After intravascular injection of the dextrans, mean fluorescence intensities of both dextrans were measured in the cardinal vein of living zebrafish (4 days postfertilization) by confocal microscopy over time. We demonstrated that injected 10-kDa dextran was rapidly cleared from the circulation, became visible in the lumen of the pronephric tubule, quickly accumulated in tubular cells, and was detectably excreted at the cloaca. In contrast, 500-kDa dextran could not be visualized in the tubule at any time point. To check whether alterations in glomerular function can be quantified by our method, we injected morpholino oligonucleotides (MOs) against zebrafish nonmuscle myosin heavy chain IIA (zMyh9) or apolipoprotein L1 (zApol1). While glomerular filtration was reduced in zebrafish nonmuscle myosin heavy chain IIA MO-injected larvae, glomerular barrier function remained intact. In contrast, in zebrafish apolipoprotein L1 MO-injected larvae, glomerular barrier function was compromised as 500-kDa dextran disappeared from the circulation and became visible in tubular cells. In summary, we present a novel method that allows to simultaneously assess glomerular filtration and barrier function in live zebrafish.
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Brabec, Marianne, Daniela Schober, Ernst Wagner, et al. "Opening of Size-Selective Pores in Endosomes during Human Rhinovirus Serotype 2 In Vivo Uncoating Monitored by Single-Organelle Flow Analysis." Journal of Virology 79, no. 2 (2005): 1008–16. http://dx.doi.org/10.1128/jvi.79.2.1008-1016.2005.
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ABSTRACT The effect of virus uncoating on endosome integrity during the early steps in viral infection was investigated. Using fluid-phase uptake of 10- and 70-kDa dextrans labeled with a pH-dependent fluorophore (fluorescein isothiocyanate [FITC]) and a pH-independent fluorophore (cyanine 5 [Cy5]), we determined the pHs of labeled compartments in intact HeLa cells by fluorescence-activated cell sorting analysis. Subsequently, the number and pH of fluorescent endosomes in cell homogenates were determined by single-organelle flow analysis. Cointernalization of adenovirus and 70-kDa FITC- and Cy5-labeled dextran (FITC/Cy5-dextran) led to virus-induced endosomal rupture, resulting in the release of the marker from the low-pH environment into the neutral cytosol. Consequently, in the presence of adenovirus, the number of fluorescent endosomes was reduced by 40% compared to that in the control. When human rhinovirus serotype 2 (HRV2) was cointernalized with 10-and 70-kDa FITC/Cy5-dextrans, the 10-kDa dextran was released, whereas the 70-kDa dextran remained within the endosomes, which also maintained their low pH. These data demonstrate that pores are generated in the membrane during HRV2 uncoating and RNA penetration into the cytosol without gross damage of the endosomes; 10-kDa dextran can access the cytosol through these pores. Whereas rhinovirus-mediated pore formation was prevented by the vacuolar ATPase inhibitor bafilomycin A1, adenovirus-mediated endosomal rupture also occurred in the presence of the inhibitor. This finding is in keeping with the low-pH requirement of HRV2 infection; for adenovirus, no pH dependence for endosomal escape was found with this drug.
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Velásquez Caro, Juan. "Efecto de la concentración de inóculo y tiempo de fermentación en la producción de dextranos por Leuconostoc mesenteroides subsp. mesenteroides aislados de jugo de caña de azúcar." Revista Científica Pakamuros 1, no. 1 (2013): 11. http://dx.doi.org/10.37787/pakamuros-unj.v1i1.1.
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Las variables ensayadas fueron: concentración de inóculo 5 %, 10 % y 15 % y tiempo de fermentación 24, 36 y 72 horas. El biorreactor fue alimentado con 250 mL de caldo hipersacarosado. La concentración del inóculo se determinó con la ayuda de la cámara de Newbahuer para luego estandarizarla a 1,6 x 10 cel/mL en volúmenes de 5 %, 10 % y 15 % constituyendo cada uno los inóculos definitivos. La eficiencia de la producción de dextranos fue calculada de acuerdo a la Concentración de dextrano (g/L), Productividad de dextrano (g/L.h) y Conversión de sustrato (%). La optimización de variables fue obtenida con la Prueba de Análisis de Varianza (ANAVA) y la Prueba Discriminatoria de Tukey. Las condiciones óptimas para la producción de dextranos por Leuconostoc mesenteroides subsp. mesenteroides fueron a partir de una concentración de inóculo de 5 % y tiempo de fermentación de 36 h, produciendo una concentración de dextrano de 30,730 g/L, productividad de 0,853 g/L.h y conversión de sustrato de 30,730%.
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Esawy, Mona A., Sara H. Mansour, Eman F. Ahmed, Naziha M. Hassanein, and Hesham A. El Enshasy. "Characterization of Extracellular Dextranase from a Novel HalophilicBacillus subtilis NRC-B233ba Mutagenic Honey Isolate under Solid State Fermentation." E-Journal of Chemistry 9, no. 3 (2012): 1494–510. http://dx.doi.org/10.1155/2012/860619.
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Bacillus subtilis NRC-B233bwas isolated from Libyan honey sample proved to be a potent dextranase producer by applying solid state fermentation and utilizing corn flour as the sole carbon source. The optimized culture conditions for dextranase productions were 37°C, pH 10, 32 h, and 20% (v/w) moisture content. A unique character of this isolate is its ability to produce steady dextranase irrespective to the presence of NaCl in the medium. The addition of 0.175 Mm CrCl3 increased the enzyme production by about 4.5 fold. Further improvement in enzyme production was achieved by simple UV mutation which increased the enzyme production up to about 2842 U/g. The crude extract has been partially purified about 112-fold from crude extract by only two purification steps involving ultra-filtration. The partially purified dextranase showed its maximum activity at pH 9.2 and 70°C. It retained full activity (100%) at 75°C for one hour. Dextranase activity increased about 4 fold in the presence of 10% NaCl. This enzyme showed variable degradation effect on different types of dextran and its derivatives. The treatment of viscous sugar cane juice with the enzyme preparation resulted in clear visual dextran hydrolysis. These results suggest that the dextranase produced byBacillus subtilis NRC-B233bis industrially applicable.
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Henry, Charmaine B. S., and Brian R. Duling. "Permeation of the luminal capillary glycocalyx is determined by hyaluronan." American Journal of Physiology-Heart and Circulatory Physiology 277, no. 2 (1999): H508—H514. http://dx.doi.org/10.1152/ajpheart.1999.277.2.h508.
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The endothelial cell glycocalyx influences blood flow and presents a selective barrier to movement of macromolecules from plasma to the endothelial surface. In the hamster cremaster microcirculation, FITC-labeled Dextran 70 and larger molecules are excluded from a region extending almost 0.5 μm from the endothelial surface into the lumen. Red blood cells under normal flow conditions are excluded from a region extending even farther into the lumen. Examination of cultured endothelial cells has shown that the glycocalyx contains hyaluronan, a glycosaminoglycan which is known to create matrices with molecular sieving properties. To test the hypothesis that hyaluronan might be involved in establishing the permeation properties of the apical surface glycocalyx in vivo, hamster microvessels in the cremaster muscle were visualized using video microscopy. After infusion of one of several FITC-dextrans (70, 145, 580, and 2,000 kDa) via a femoral cannula, microvessels were observed with bright-field and fluorescence microscopy to obtain estimates of the anatomic diameters and the widths of fluorescent dextran columns and of red blood cell columns (means ± SE). The widths of the red blood cell and dextran exclusion zones were calculated as one-half the difference between the bright-field anatomic diameter and the width of the red blood cell column or dextran column. After 1 h of treatment with active Streptomyces hyaluronidase, there was a significant increase in access of 70- and 145-kDa FITC-dextrans to the space bounded by the apical glycocalyx, but no increase in access of the red blood cells or in the anatomic diameter in capillaries, arterioles, and venules. Hyaluronidase had no effect on access of FITC-Dextrans 580 and 2,000. Infusion of a mixture of hyaluronan and chondroitin sulfate after enzyme treatment reconstituted the glycocalyx, although treatment with either molecule separately had no effect. These results suggest that cell surface hyaluronan plays a role in regulating or establishing permeation of the apical glycocalyx to macromolecules. This finding and our prior observations suggest that hyaluronan and other glycoconjugates are required for assembly of the matrix on the endothelial surface. We hypothesize that hyaluronidase creates a more open matrix, enabling smaller dextran molecules to penetrate deeper into the glycocalyx.
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Seksek, Olivier, Joachim Biwersi, and A. S. Verkman. "Translational Diffusion of Macromolecule-sized Solutes in Cytoplasm and Nucleus." Journal of Cell Biology 138, no. 1 (1997): 131–42. http://dx.doi.org/10.1083/jcb.138.1.131.
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Fluorescence recovery after photobleaching (FRAP) was used to quantify the translational diffusion of microinjected FITC-dextrans and Ficolls in the cytoplasm and nucleus of MDCK epithelial cells and Swiss 3T3 fibroblasts. Absolute diffusion coefficients (D) were measured using a microsecond-resolution FRAP apparatus and solution standards. In aqueous media (viscosity 1 cP), D for the FITC-dextrans decreased from 75 to 8.4 × 10−7 cm2/s with increasing dextran size (4–2,000 kD). D in cytoplasm relative to that in water (D/Do) was 0.26 ± 0.01 (MDCK) and 0.27 ± 0.01 (fibroblasts), and independent of FITC-dextran and Ficoll size (gyration radii [RG] 40–300 Å). The fraction of mobile FITC-dextran molecules (fmob), determined by the extent of fluorescence recovery after spot photobleaching, was >0.75 for RG < 200 Å, but decreased to <0.5 for RG > 300 Å. The independence of D/Do on FITC-dextran and Ficoll size does not support the concept of solute “sieving” (size-dependent diffusion) in cytoplasm. Photobleaching measurements using different spot diameters (1.5–4 μm) gave similar D/Do, indicating that microcompartments, if present, are of submicron size. Measurements of D/Do and fmob in concentrated dextran solutions, as well as in swollen and shrunken cells, suggested that the low fmob for very large macromolecules might be related to restrictions imposed by immobile obstacles (such as microcompartments) or to anomalous diffusion (such as percolation). In nucleus, D/Do was 0.25 ± 0.02 (MDCK) and 0.27 ± 0.03 (fibroblasts), and independent of solute size (RG 40–300 Å). Our results indicate relatively free and rapid diffusion of macromolecule-sized solutes up to approximately 500 kD in cytoplasm and nucleus.
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Llamas-Arriba, María Goretti, Annel M. Hernández-Alcántara, Mari Luz Mohedano, et al. "Lactic Acid Bacteria Isolated from Fermented Doughs in Spain Produce Dextrans and Riboflavin." Foods 10, no. 9 (2021): 2004. http://dx.doi.org/10.3390/foods10092004.
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Many lactic acid bacteria (LAB) produce metabolites with applications in the food industry, such as dextran-type exopolysaccharides (EPS) and riboflavin (vitamin B2). Here, 72 bacteria were isolated from sourdoughs made by Spanish bread-makers. In the presence of sucrose, colonies of 22 isolates showed a ropy phenotype, and NMR analysis of their EPS supported that 21 of them were dextran producers. These isolates were identified by their random amplified polymorphic DNA (RAPD) patterns and their rrs and pheS gene sequences as LAB belonging to four species (Weissella cibaria, Leuconostoc citreum, Leuconostoc falkenbergense and Leuconostoc mesenteroides). Six selected strains from the Leuconostoc (3) and Weissella (3) genera grew in the absence of riboflavin and synthesized vitamin B2. The EPS produced by these strains were characterized as dextrans by physicochemical analysis, and the L. citreum polymer showed an unusually high degree of branching. Quantification of the riboflavin and the EPS productions showed that the W. cibaria strains produce the highest levels (585–685 μg/and 6.5–7.4 g/L, respectively). Therefore, these new LAB strains would be good candidates for the development of fermented foods bio-fortified with both dextrans and riboflavin. Moreover, this is the first report of riboflavin and dextran production by L. falkenbergense.
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Cardoso, Paulo Francisco Guerreiro, Rogério Pazetti, Henrique Takachi Moriya, et al. "Modelo experimental de perfusão pulmonar ex vivo em ratos: avaliação de desempenho de pulmões submetidos à administração de prostaciclina inalada versus parenteral." Jornal Brasileiro de Pneumologia 37, no. 5 (2011): 589–97. http://dx.doi.org/10.1590/s1806-37132011000500005.
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OBJETIVO: Apresentar um modelo experimental de administração de prostaglandina I2 (PGI2) por via inalatória vs. parenteral e avaliar o desempenho funcional dos pulmões em um sistema de perfusão pulmonar ex vivo. MÉTODOS: Quarenta ratos Wistar foram anestesiados, ventilados, submetidos a laparotomia com ressecção do esterno e anticoagulados. O tronco da artéria pulmonar foi canulado. Todos os animais foram submetidos a ventilação mecânica. Os animais foram randomizados em quatro grupos (10 ratos/grupo): salina nebulizada (SN); salina parenteral (SP); PGI2 nebulizada (PGI2N); e PGI2 parenteral (PGI2P). A dose de PGI2 nos grupos PGI2N e PGI2P foi de 20 e 10 µg/kg, respectivamente. Os blocos cardiopulmonares foram submetidos in situ a perfusão anterógrada com solução de baixo potássio e dextrana a 4ºC via artéria pulmonar, extraídos em bloco e armazenados a 4ºC por 6 h. Os blocos foram ventilados e perfundidos em um sistema ex vivo por 50 min, sendo obtidas medidas de mecânica ventilatória, hemodinâmica e trocas gasosas. RESULTADOS: Houve redução da pressão arterial pulmonar média após a nebulização em todos os grupos (p < 0,001), sem diferença entre os grupos. Na perfusão ex vivo, a mecânica ventilatória não diferiu entre os grupos. Houve redução da capacidade relativa de oxigenação ao longo da perfusão nos grupos SN e SP (p = 0,04), e houve aumento significativo da pressão arterial pulmonar no grupo SN. CONCLUSÕES: O modelo experimental de administração de PGI2 na extração pulmonar é exequível e confiável. Na reperfusão, os resultados de hemodinâmica e de trocas gasosas demonstraram tendência a um melhor desempenho com o uso de PGI2 do que com solução salina.
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Ebaya, Mahasen Mohamed Ahmed, Mohammed El-Mowafy, Mohamed Mohamed Adel El-Sokkary, and Ramadan Hassan. "Purification, Characterization, and Biocatalytic and Antibiofilm Activity of a Novel Dextranase from Talaromyces sp." International Journal of Microbiology 2020 (November 11, 2020): 1–11. http://dx.doi.org/10.1155/2020/9198048.
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Dextranase is a useful enzyme that catalyzes the degradation of dextran to low-molecular-weight fractions, which have many critical commercial and clinical applications. Endophytic fungi represent a source of both high heat-stable and pH-stable enzymes. In this study, from Delonix regia bark by plate assay, out of 12 isolated fungal strains, hyaline zones were detected in only one strain. By using the standard ITS rDNA sequencing analysis, the isolated strain was identified as Talaromyces sp. In the case of carbon source, in a medium containing 1% dextran T2000 as the sole carbon source, the maximum dextranase activity reached approximately 120 U/ml after incubation of 2 days where the optimum pH was 7.4. Peptone addition to the production medium as a sole nitrogen source was accompanied by a significant increase in the dextranase production. Similarly, some metal ions, such as Fe2+ and Zn2+, increased significantly enzyme production. However, there was no significant difference resulting from the addition of Cu2+. The crude dextranase was purified by ammonium sulfate fractionation, followed by Sephadex G100 chromatography with 28-fold purification. The produced dextranase was 45 kDa with an optimum activity at 37°C and a pH of 7. Moreover, the presence of MgSO4, FeSO4, and NH4SO4 increased the purified dextranase activity; however, SDS and EDTA decreased it. Interestingly, the produced dextranase expressed remarkable pH stability, temperature stability, and biofilm inhibition activity, reducing old-established biofilm by 86% and biofilm formation by 6%.
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Cakic, Milorad, Goran Nikolic, Ljubomir Ilic, and Slobodan Stankovic. "Synthesis and FTIR characterization of some dextran sulphates." Chemical Industry and Chemical Engineering Quarterly 11, no. 2 (2005): 74–78. http://dx.doi.org/10.2298/ciceq0502074c.
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The result of the synthesis and investigation of FTIR spectra of some dextran sulphates and their sodium (Na) salts are presented. A synthesis was conducted (under different reaction parameters) of esters with various degrees of esterification (from 1.0 to 2.3). FTIR investigations were performed on sulphates of low and high molecular hydrogenated dextrans of various molecular masses (Mw of 5000, 7000, 8000, 40000 and 500000). Particular care was taken to determine the degree of linearity of the synthesized dextran sulphates, the conformation of glucopyranosyl units and the way the sulpho groups and the water were bonded in their structures.
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Jones, J. L., R. E. Jones, and G. Balasky. "Microlesion formation in myocardial cells by high-intensity electric field stimulation." American Journal of Physiology-Heart and Circulatory Physiology 253, no. 2 (1987): H480—H486. http://dx.doi.org/10.1152/ajpheart.1987.253.2.h480.
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Arrhythmias, S-T segment changes, immediate refibrillation, and other signs of dysfunction are often observed after clinical and experimental transthoracic defibrillation. In vitro studies suggested that shock-induced dysfunction is induced by sarcolemmal dielectric breakdown accompanied by ionic exchanges through transient, shock-induced microlesions in the sarcolemma. To test this hypothesis, cultured chick embryo myocardial cells were shocked in media containing fluorescein isothiocyanate-labeled dextrans (FITC-dextrans) ranging in molecular mass from 4 to 70 kDa, using electric field stimulation 5 ms in duration and ranging in intensity from 0 to 200 V/cm. Results showed that the percentage of cells incorporating 4- to 20-kDa dextrans increased in a dose-dependent manner. The 4- and 10-kDa dextrans were incorporated beginning at intensities of 50–100 V/cm. Dextran incorporation corresponded with shock intensities which produced a shock-induced arrest of spontaneous contraction lasting 1 min. The 20-kDa dextrans were incorporated following 150- and 200-V/cm shocks. Shocks of these intensities also produced a transient postshock contracture. Larger dextrans (40 and 70 kDa) were not incorporated. These results suggest the formation of transient sarcolemmal microlesions having a diameter of 45-60 A during high-intensity electric field stimulation.
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Davidovic, Sladjana, Miona Miljkovic, Dusan Antonovic, Mirjana Rajilic-Stojanovic, and Suzana Dimitrijevic-Brankovic. "Water Kefir grain as a source of potent dextran producing lactic acid bacteria." Chemical Industry 69, no. 6 (2015): 595–604. http://dx.doi.org/10.2298/hemind140925083d.
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Water kefir is abeverage fermented by a microbial consortium captured in kefir grains. The kefir grains matrix is composed of polysaccharide, primarily dextran, whichis produced by members of the microbial consortium. In this study, we have isolated lactic acid bacteria (LAB) from non-commercial water kefir grains (from Belgrade, Serbia) and screened for dextran production. Among twelve Lisolates threeproduced slime colonies on modified MRS (mMRS) agar containing sucrose instead of glucoseand were presumed to produce dextran. Three LABwere identified based on morphological, physiological and biochemical characteristics and 16S rRNA sequencing as Leuconostoc mesenteroides(strains T1 and T3) and Lactobacillus hilgardii (strain T5). The isolated strains were able to synthesize a substantial amount of dextran in mMRS broth containing 5% sucrose. Maximal yields (11.56, 18.00 and 18.46 g/l) were obtained after 16h, 20h and 32h for T1, T3 and T5, respectively. Optimal temperature for dextran production was 23oC for two Leuconostoc mesenteroides strains and 30oC for Lactobacillus hilgardii strain. The produced dextrans were identified based on paper chromatography while the main structure characteristics of purified dextranwere observed by FT-IR spectroscopy. Our study shows that water kefir grains are a natural source of potent dextranproducing LAB.
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Holt, Scott M., and Gregory L. Cote. "Differentiation of Dextran-ProducingLeuconostoc Strains by a Modified Randomly Amplified Polymorphic DNA Protocol." Applied and Environmental Microbiology 64, no. 8 (1998): 3096–98. http://dx.doi.org/10.1128/aem.64.8.3096-3098.1998.
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ABSTRACT Seven dextran-producing Leuconostoc strains were differentiated by using a modified randomly amplified polymorphic DNA (RAPD) protocol that incorporated specific primers designed from conserved regions of dextransucrase genes. RAPD profiles showed intraspecies differences among the Leuconostoc mesenteroides strains tested. This modified RAPD protocol will aid in the differentiation of polymer-producing leuconostocs, which are currently distinguished by time-consuming analyses of the dextrans they synthesize.
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Chu, Chong Woo, Je Ho Ryu, Young-IL Jeong, et al. "Redox-Responsive Nanophotosensitizer Composed of Chlorin e6-Conjugated Dextran for Photodynamic Treatment of Colon Cancer Cells." Journal of Nanomaterials 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/4075803.
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We synthesized dextran-chlorin e6 conjugates having disulfide linkage for specific targeting of colonic region and cancer cells. Reductive end group of dextran was treated with sodium borocyanohydride and conjugated with cystamine. Cystamine end group was conjugated with carboxylic acid of chlorin e6 (DEX6ss). DEX6ss conjugates were formed as spherical nanoparticles with small sizes less than 100 nm. Chlorin e6 (Ce6) was specifically released from DEX6ss nanoparticles in the presence of dextranase or glutathione (GSH), indicating that DEX6ss nanoparticles have responsiveness against dextranase and redox-environment. In dark-toxicity test using normal cells and cancer cells, Ce6 and DEX6ss nanoparticles were practically nontoxic. Intracellular delivery of DEX6ss nanoparticles was significantly improved compared to Ce6 itself. DEX6ss nanoparticles achieved significantly higher ROS production and phototoxicity against HCT116 colon cancer cells than Ce6 itself. Furthermore, DEX6ss nanoparticles showed enhanced tumor targeting efficiency and longer retention in the tumor tissues atin vivoanimal study with HCT116 tumor-bearing mice. Furthermore, DEX6ss nanoparticles have responsiveness against colonic enzyme, dextranase, indicating that they have potential of colon-specific delivery and dextranase-specific drug delivery capacity. We fabricated colon-specific and tumor-targetable nanophotosensitizer using DEX6ss conjugates. They showed improved cellular uptake ratio, phototoxicity, and colon-specificity. We suggest that DEX6ss nanoparticles can be considered as a promising candidate for PDT of colon cancer.
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Whiteside, C., and M. Silverman. "Postglomerular capillary solute flux restricted by shape and charge in the dog." American Journal of Physiology-Renal Physiology 253, no. 3 (1987): F500—F512. http://dx.doi.org/10.1152/ajprenal.1987.253.3.f500.
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The permselectivity characteristics of the postglomerular (PG) microcirculation in dog kidney were investigated employing 3H-labeled cationic (DEAE) and anionic sulfated dextrans (dextran-SO4) ranging from 19 to 29 A Stokes-Einstein Radius. With the use of the multiple-indicator dilution (MID) technique, a bolus injection was made into the left renal artery and timed serial samples were obtained from renal venous and urine outflows. The injection solution contained 125I-labeled albumin (plasma reference), [14C]inulin and/or creatinine (glomerular and interstitial references), and a test [3H]dextran probe. A control run was carried out with tracer, then charge interaction was analyzed by repeating the MID run with excess unlabeled compound or after protamine sulfate infusion. After loading, renal vein recovery and mean transit time (t) were unchanged relative to [14C]inulin for [3H]dextran-SO4. But excess DEAE resulted in reduced recovery and decreased t for [3H]DEAE. After protamine sulfate, the renal vein and urine recoveries of [3H]dextran-SO4 decreased and the renal vein t increased. These findings demonstrate saturable anionic binding sites in the PG microcirculation. Under conditions where charge interaction was eliminated, the ratio of renal vein t for 125I-albumin to cationic or anionic dextran was always less than its ratio to neutral dextran, implying a larger apparent volume of distribution. We concluded that PG capillaries also limit solute flux on the basis of shape.
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Serrat, Maria A., Morgan L. Efaw, and Rebecca M. Williams. "Hindlimb heating increases vascular access of large molecules to murine tibial growth plates measured by in vivo multiphoton imaging." Journal of Applied Physiology 116, no. 4 (2014): 425–38. http://dx.doi.org/10.1152/japplphysiol.01212.2013.
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Advances in understanding the molecular regulation of longitudinal growth have led to development of novel drug therapies for growth plate disorders. Despite progress, a major unmet challenge is delivering therapeutic agents to avascular-cartilage plates. Dense extracellular matrix and lack of penetrating blood vessels create a semipermeable “barrier,” which hinders molecular transport at the vascular-cartilage interface. To overcome this obstacle, we used a hindlimb heating model to manipulate bone circulation in 5-wk-old female mice ( n = 22). Temperatures represented a physiological range of normal human knee joints. We used in vivo multiphoton microscopy to quantify temperature-enhanced delivery of large molecules into tibial growth plates. We tested the hypothesis that increasing hindlimb temperature from 22°C to 34°C increases vascular access of large systemic molecules, modeled using 10, 40, and 70 kDa dextrans that approximate sizes of physiological regulators. Vascular access was quantified by vessel diameter, velocity, and dextran leakage from subperichondrial plexus vessels and accumulation in growth plate cartilage. Growth plate entry of 10 kDa dextrans increased >150% at 34°C. Entry of 40 and 70 kDa dextrans increased <50%, suggesting a size-dependent temperature enhancement. Total dextran levels in the plexus increased at 34°C, but relative leakage out of vessels was not temperature dependent. Blood velocity and vessel diameter increased 118% and 31%, respectively, at 34°C. These results demonstrate that heat enhances vascular carrying capacity and bioavailability of large molecules around growth plates, suggesting that temperature could be a noninvasive strategy for modulating delivery of therapeutics to impaired growth plates of children.
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Sarbini, Shahrul R., Sofia Kolida, Eddie R. Deaville, Glenn R. Gibson, and Robert A. Rastall. "Potential of novel dextran oligosaccharides as prebiotics for obesity management throughin vitroexperimentation." British Journal of Nutrition 112, no. 8 (2014): 1303–14. http://dx.doi.org/10.1017/s0007114514002177.
Full textAbstract:
The energy-salvaging capacity of the gut microbiota from dietary ingredients has been proposed as a contributing factor for the development of obesity. This knowledge generated interest in the use of non-digestible dietary ingredients such as prebiotics to manipulate host energy homeostasis. In the present study, thein vitroresponse of obese human faecal microbiota to novel oligosaccharides was investigated. Dextrans of various molecular weights and degrees of branching were fermented with the faecal microbiota of healthy obese adults in pH-controlled batch cultures. Changes in bacterial populations were monitored using fluorescentin situhybridisation and SCFA concentrations were analysed by HPLC. The rate of gas production and total volume of gas produced were also determined. In general, the novel dextrans and inulin increased the counts of bifidobacteria. Some of the dextrans were able to alter the composition of the obese human microbiota by increasing the counts ofBacteroides–Prevotellaand decreasing those ofFaecalibacterium prausnitziiandRuminococcus bromii/R. flavefaciens. Considerable increases in SCFA concentrations were observed in response to all substrates. Gas production rates were similar during the fermentation of all dextrans, but significantly lower than those during the fermentation of inulin. Lower total gas production and shorter time to attain maximal gas production were observed during the fermentation of the linear 1 kDa dextran than during the fermentation of the other dextrans. The efficacy of bifidobacteria to ferment dextrans relied on the molecular weight and not on the degree of branching. In conclusion, there are no differences in the profiles between the obese and lean human faecal fermentations of dextrans.
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Zhao, Yan, and Yong Gang Tu. "Introduction on a Kind of Environmental Biological Materials - Dextrins." Advanced Materials Research 671-674 (March 2013): 1889–92. http://dx.doi.org/10.4028/www.scientific.net/amr.671-674.1889.
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Dextrins are important starch derivatives, they are a kind of environmental biological materials and widely used in industry. The paper gave a full introduction about the definition, properties, application and the recent research situation of pyrolysis dextrin, cyclodextrin, maltodextrin and β-limit dextrin, their development tendency are also discussed.
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COLE, LOUISE, JULLIAN COLEMAN, DAVID EVANS, and CHRIS HAWES. "Internalisation of fluorescein isothiocyanate and fluorescein isothiocyanatedextran by suspension-cultured plant cells." Journal of Cell Science 96, no. 4 (1990): 721–30. http://dx.doi.org/10.1242/jcs.96.4.721.
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The uptake of pure non-conjugated fluorescein isothiocyanate (FITC) and of the membraneimpermeant probe FITC—dextran into suspensioncultured carrot cells and protoplasts has been investigated. Commercial samples of a 70K (K=103Mr) FITC—dextran were shown to contain contaminant FITC and/or its degradation products, which were rapidly internalised into the vacuolar system of both cells and protoplasts. However, purified samples of the 70K FITC—dextran were taken up into the vacuoles of cells but not protoplasts after a lh incubation period. This apparent difference in the ability of cells and protoplasts to internalise FITC—dextrans was confirmed using samples of both commercial and purified 20K FITC—dextran as putative endocytotic probes. Both confocal and conventional fluorescence microscopy of FITC—treated cells have shown that FITC was internalised into similar intracellular compartments as was observed in cells treated with three-times purified 70K FITC—dextran. Thus, FITC was a useful fluorophore for rapidly labelling both the putative endocytotic compartments and the pleiomorphic vacuolar system of carrot cells. Kinetic studies indicated that FITC entered the cell by diffusion in the form of the neutral molecule. We have shown that treatment of cells or protoplasts with the drug Probenecid reversibly inhibited the uptake of FITC from the cytoplasm into the vacuole. In addition, the uptake of FITC into isolated vacuoles was enhanced in the presence of Mg-ATP
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Lemley, K. V. "Glomerular size selectivity during protein overload in the rat." American Journal of Physiology-Renal Physiology 264, no. 6 (1993): F1046—F1051. http://dx.doi.org/10.1152/ajprenal.1993.264.6.f1046.
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Differential glomerular permeability to macromolecules as a function of their size (size permselectivity) is altered in experimental models of proteinuric renal disease. Size permselectivity during protein overload proteinuria was examined using urinary clearances of neutral dextrans in anesthetized Wistar-Furth rats. The animals were studied 3-4 h after the last of six twice-a-day intraperitoneal injections of either bovine serum albumin (BSA) or ovalbumin (OA) or of vehicle alone (controls). Glomerular filtration rates did not differ significantly among the three groups. OA-treated (n = 4) and control (n = 5) rats had virtually identical fractional dextran clearances over almost the entire molecular size range from 18 to 58 A Stokes-Einstein radius. In contrast, BSA-treated rats (n = 5) had elevated fractional clearances for medium-sized dextrans with the increases reaching statistical significance at radii of 40 A (+22.7% vs. control) and 44 A (+20.4%). Fractional clearances for BSA-treated rats returned to control values for larger dextrans. These findings demonstrate a significant size permselectivity defect in BSA overload, although not in OA overload.