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Intracellular Uptake (intracellular + uptake)
Selected AbstractsMUCILAGINOUS CAPSULE ADSORPTION AND INTRACELLULAR UPTAKE OF COPPER BY KIRCHNERIELLA APERTA (CHLOROCOCCALES)1JOURNAL OF PHYCOLOGY, Issue 2 2002Ana T. Lombardi The purpose of the present investigation was to evaluate possible ecological and physiological functions of mucilaginous capsules produced by the freshwater algae Kirchneriella aperta Teiling (Chlorococcales) as related to copper ions. All experiments were performed using synthetic media under laboratory-controlled conditions. Copper interactions were investigated by distinguishing between adsorption onto the mucilaginous material present at the surface of the cells, intracellular uptake, and differentiation between total dissolved copper and free copper ions in the culture medium. Kirchneriella aperta is sensitive to copper, as revealed by a 96-h EC50 value of 10,9.22 M Cu2+. We demonstrated that the mucilaginous capsules were able to sequester copper ions from the medium through a passive mechanism, thus providing the cell with a mechanism able to postpone the toxic effects of copper. The organic material that diffuses into the test medium as well as the mucilaginous capsules produced by K. aperta both effectively complex copper; thus, toxicity must be related to free copper ions and not the total dissolved copper concentration in the medium. [source] Intracellular Uptake and Photodynamic Activity of Water-Soluble [60]- and [70]Fullerenes Incorporated in LiposomesCHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2008Yuki Doi Abstract Water-soluble fullerenes have attracted attention as promising compounds that have been used to forge new paths in the field of photo-biochemistry. To prepare water-soluble fullerenes, we employed lipid-membrane-incorporated fullerenes (LMICx; x=60 or 70) by using the fullerene exchange method from a ,-cyclodextrin (,-CD) cavity to vesicles. LMIC60 have low toxicity in the dark and engender cell death by photoirradiation (,>350,nm). Furthermore, the photodynamic activity of LMIC70 is 4.7-fold that of LMIC60 for the same photon flux (,>400,nm). One of the reasons for the higher phototoxicity of LMIC70 is the higher generation of singlet oxygen (1O2) in LMIC70 than in LMIC60. The difference between LMIC60 and LMIC70 is considered to be simply derived from the amount of light absorption in the 400,700,nm region that is suitable for photodynamic therapy (PDT). To the best of our knowledge, this is the first case in which biological activity of C70 and its derivatives toward HeLa cells has been assayed. [source] Intracellularly Degradable Polyelectrolyte Microcapsules,ADVANCED MATERIALS, Issue 8 2006G. De, Geest Intracellular uptake and degradation of polyelectrolyte capsules is reported in this work. Two types of intracellular degradable capsules are described: enzyme-sensitive and hydrolysis- sensitive capsules (see figure). The results may be a significant step towards the biomedical application of polyelectrolyte capsules. [source] Intracellular uptake and trafficking of Pluronic micelles in drug-sensitive and MDR cells: Effect on the intracellular drug localizationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2002Natalya Rapoport Abstract The intracellular uptake and localization of a fluorescently labeled Pluronic P-105 in HL-60 leukemia cells and in A2780 drug-sensitive and A2780/ADR MDR ovarian carcinoma cells were characterized by flow cytometry and fluorescence microscopy. Pluronic P-105 molecules were labeled with a pH-sensitive fluorescent label, 5-(and 6-)carboxy-2,7,-dichlorofluorescein. The fluorescence intensity of labeled Pluronic was about twofold higher at pH 7.4 than at pH 5.5. At Pluronic concentrations exceeding the critical micelle concentration (cmc), flow cytometry histograms manifested bimodal distribution of cell fluorescence for all types of cells. Cell population characterized by higher fluorescence intensity presumably resulted from Pluronic transfer from the acidic environment of cytoplasmic vesicles (endosomes or lysosomes) into the neutral environment of the cytoplasm and cell nuclei, which suggested the permeabilization of the membranes of acidic vesicle by Pluronic molecules. For the MDR cells, the bimodal distribution of cell fluorescence was already observed at very low Pluronic concentrations in the incubation medium (i.e., below the cmc). The data suggest that the membranes of acidic vesicles of MDR cells are more susceptible to the action of polymeric surfactants than those of drug-sensitive cells. Permeabilization of acidic vesicles had a dramatic effect on the intracellular trafficking of drugs: when delivered in PBS, the anthracyclin drug ruboxyl (Rb) sequestered in cytoplasmic vesicles and was excluded from cell nuclei; however, when delivered in Pluronic micelles, drug accumulated in cell nuclei. Drug uptake from/with Pluronic micelles was substantially enhanced by ultrasound. These findings suggest that the nuclear accumulation of drugs internalized via fluid-phase endocytosis can be enhanced by the application of Pluronic micelles and can be further augmented by ultrasonic irradiation. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:157,170, 2002 [source] Sulfated polysaccharides inhibit the catabolism and loss of both large and small proteoglycans in explant cultures of tendonFEBS JOURNAL, Issue 15 2006Tom Samiric This study investigated the effects of two highly sulfated polysaccharides, calcium pentosan polysulfate and heparin, on the loss of newly synthesized proteoglycans from the matrix of explant cultures of bovine tendon. The tensional region of deep flexor tendon was incubated with [35S]sulfate for 6 h and then placed in culture for up to 15 days. The amount of radiolabel associated with proteoglycans lost to the medium and retained in the matrix was determined for each day in culture. It was shown that both sulfated polysaccharides at concentrations of 1000 µg·mL,1 inhibited the loss of 35S-labeled large and small proteoglycans from the matrix and concomitant with this was a retention of chemical levels of proteoglycans in the explant cultures. In other explant cultures that were maintained in culture in the presence of both agents for more than 5 days after incubation with [35S]sulfate, inhibition of the intracellular catabolic pathway was evident, indicating that these highly sulfated polysaccharides also interfered with the intracellular uptake of small proteoglycans by tendon cells. [source] Fluorescent risedronate analogues reveal bisphosphonate uptake by bone marrow monocytes and localization around osteocytes in vivoJOURNAL OF BONE AND MINERAL RESEARCH, Issue 3 2010Anke J Roelofs Abstract Bisphosphonates are effective antiresorptive agents owing to their bone-targeting property and ability to inhibit osteoclasts. It remains unclear, however, whether any non-osteoclast cells are directly affected by these drugs in vivo. Two fluorescent risedronate analogues, carboxyfluorescein-labeled risedronate (FAM-RIS) and Alexa Fluor 647,labeled risedronate (AF647-RIS), were used to address this question. Twenty-four hours after injection into 3-month-old mice, fluorescent risedronate analogues were bound to bone surfaces. More detailed analysis revealed labeling of vascular channel walls within cortical bone. Furthermore, fluorescent risedronate analogues were present in osteocytic lacunae in close proximity to vascular channels and localized to the lacunae of newly embedded osteocytes close to the bone surface. Following injection into newborn rabbits, intracellular uptake of fluorescently labeled risedronate was detected in osteoclasts, and the active analogue FAM-RIS caused accumulation of unprenylated Rap1A in these cells. In addition, CD14high bone marrow monocytes showed relatively high levels of uptake of fluorescently labeled risedronate, which correlated with selective accumulation of unprenylated Rap1A in CD14+ cells, as well as osteoclasts, following treatment with risedronate in vivo. Similar results were obtained when either rabbit or human bone marrow cells were treated with fluorescent risedronate analogues in vitro. These findings suggest that the capacity of different cell types to endocytose bisphosphonate is a major determinant for the degree of cellular drug uptake in vitro as well as in vivo. In conclusion, this study shows that in addition to bone-resorbing osteoclasts, bisphosphonates may exert direct effects on bone marrow monocytes in vivo. © 2010 American Society for Bone and Mineral Research [source] Equilibrium loading of cells with macromolecules by ultrasound: Effects of molecular size and acoustic energyJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2002Héctor R Guzmán Abstract Ultrasound has been shown to deliver small compounds, macromolecules, and DNA into cells, which suggests potential applications in drug and gene delivery. However, the effect of molecular size on intracellular uptake has not been quantified. This study measured the effect of molecule size (calcein, 623 Da; bovine serum albumin, 66 kDa; and two dextrans, 42 and 464 kDa) on molecular uptake and cell viability in DU145 prostate cancer cells exposed to 500 kHz ultrasound. Molecular uptake in viable cells was shown to be very similar for small molecules and macromolecules and found to correlate with acoustic energy exposure. Molecular uptake was seen to be heterogeneous among viable cells exposed to the same ultrasound conditions; this heterogeneity also correlated with acoustic energy exposure. In a fraction of these cells, molecular uptake reached thermodynamic equilibrium with the extracellular solution for the small molecule and all three macromolecules. The results demonstrate that ultrasound provides a means to load viable cells with large numbers of macromolecules, which may be of use for laboratory and possible clinical drug delivery applications. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:1693-1701, 2002 [source] MUCILAGINOUS CAPSULE ADSORPTION AND INTRACELLULAR UPTAKE OF COPPER BY KIRCHNERIELLA APERTA (CHLOROCOCCALES)1JOURNAL OF PHYCOLOGY, Issue 2 2002Ana T. Lombardi The purpose of the present investigation was to evaluate possible ecological and physiological functions of mucilaginous capsules produced by the freshwater algae Kirchneriella aperta Teiling (Chlorococcales) as related to copper ions. All experiments were performed using synthetic media under laboratory-controlled conditions. Copper interactions were investigated by distinguishing between adsorption onto the mucilaginous material present at the surface of the cells, intracellular uptake, and differentiation between total dissolved copper and free copper ions in the culture medium. Kirchneriella aperta is sensitive to copper, as revealed by a 96-h EC50 value of 10,9.22 M Cu2+. We demonstrated that the mucilaginous capsules were able to sequester copper ions from the medium through a passive mechanism, thus providing the cell with a mechanism able to postpone the toxic effects of copper. The organic material that diffuses into the test medium as well as the mucilaginous capsules produced by K. aperta both effectively complex copper; thus, toxicity must be related to free copper ions and not the total dissolved copper concentration in the medium. [source] Metabolism of isometamidium in hepatocytes isolated from control and inducer-treated ratsJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2006I. BOIBESSOT Little is known about the metabolism and mechanism of action of the trypanocide, isometamidium (ISM), the major drug used for prophylaxis of trypanosomiasis. We have investigated its metabolism and distribution in isolated rat hepatocytes using liquid chromatography-mass spectrometry and confocal laser scanning microscopy (CLSM). Two putative metabolites were formed, which were proposed to be a mono-acetyl derivative and an oxidized metabolite (SII). This is the first demonstration of the hepatic metabolism of ISM, as previous in vivo studies were hampered by dose-limiting toxicity and insensitive analytical methods. The intrinsic fluorescence of the drug enabled its intracellular uptake to be followed by CLSM. It is taken up rapidly into the nucleolus, nuclear membrane and endoplasmic reticulum within 5 min, and retained in the nucleus for at least 24 h. Persistent binding of ISM to cellular macromolecules may contribute to its prophylactic effect in vivo. Pretreatment of rats with 3-methylcholanthrene, phenobarbitone (PB) or the widely used pyrethroid pesticide, deltamethrin, resulted in an increase in metabolism of ISM to the proposed SII after 1 h incubation with hepatocytes. 3-methylcholanthrene was the most potent inducer, causing a maximal 19.5-fold induction of SII formation after exposure of hepatocytes to ISM for 1 h compared with formation by control hepatocytes. In comparison, at the 1 h timepoint deltamethrin pre-treatment caused a 10.2-fold induction, and PB only 8.2 fold. [source] Optimization of magnetosonoporation for stem cell labelingNMR IN BIOMEDICINE, Issue 5 2010Daohai Xie Abstract Recent advances in magnetic cell labeling have taken place with the development of a magnetosonoporation (MSP) technique. The aim of this study was to optimize the MSP protocol in order to achieve high cell viability and intracellular uptake of MR contrast agents. First, we determined the sub-optimal MSP parameters by evaluating the viabilities of C17.2 neural stem cells without Feridex using various MSP intensities ranging from 0.1 to 1,w/cm2, duty cycles at 20%, 50% or 100%, and exposure times from 1,15,min. The sub-optimized MSP parameters with cell viabilities greater than 90% were further optimized by evaluating both cell viability and intracellular iron uptake when Feridex was used. We then used the optimized MSP parameters to determinate the optimal concentration of Feridex for magnetic cell labeling. Subsequently, we validated the feasibility of using MRI to track the migration of neural stem cells from the transplanted sites to glioma masses in four mouse brains when the cells had been labeled with Feridex using the optimized MSP protocol. The MRI findings were confirmed by histological correlations. Invitro experiments demonstrated that the optimal MSP protocol was achieved at 20% duty cycle, 0.3,w/cm2 ultrasound intensity, 5-min exposure time and 1mg/mL Feridex. This study demonstrated that the optimized MSP cell labeling technique can achieve both high cell viability and intracellular uptake of MR contrast agents, and has the potential to be a useful cell labeling technique to facilitate future clinical translation of MRI-integrated cell therapy. Copyright © 2010 John Wiley & Sons, Ltd. [source] Uptake of LipiodolÔ,cytotoxic conjugates by hepatoblastoma cellsBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 4 2002E. Towu Background: Improvements in the management of children with hepatoblastoma have followed advances made in cytotoxic agents and treatment regimens. The aim of this study was to quantify the effect of LipiodolÔ, an iodinated poppy-seed oil, on the uptake of anthracyclic cytotoxic conjugates by hepatoblastoma cells in culture. Methods: Monolayer cultures of (1) a hepatoblastoma cell line generated from freshly explanted tumour tissue, (2) an immortal hepatoblastoma cell line (C3a) and (3) a human hepatocyte cell line were exposed to doxorubicin 10 µg/ml with or without 2 per cent LipiodolÔ for 1,72 h. The fluorescence intensity in the treated cells, which correlates with intracellular doxorubicin concentration, was measured by confocal laser scanning microscopy. Cytotoxicity was assessed by trypan blue exclusion and electron microscopy. Results: Doxorubicin accumulated in the nucleus and cytoplasm of all the cell lines. With LipiodolÔ, the mean fluorescence intensity of intracellular doxorubicin was increased for up to 48 h in both hepatoblastoma lines, but not in the hepatocyte cell line. LipiodolÔ increased the uptake and intracellular concentration of doxorubicin in the hepatoblastoma cells in culture. LipiodolÔ also enhanced the cytotoxicity of doxorubicin on the cultured hepatoblastoma cells. Conclusion: LipiodolÔ significantly enhanced the uptake of doxorubicin by hepatoblastoma cells in culture. LipiodolÔ,doxorubicin targeted treatment of hepatoblastoma may improve the intracellular uptake and hence cytotoxicity of doxorubicin in vivo, enabling a reduction in the total dose administered and side-effects. © 2002 British Journal of Surgery Society Ltd [source] | |||||||||||||