Dentistry Commons^™

Effect Of Voxel Size On The Accuracy Of 3d Reconstructions With Cone Beam Ct., Delphine Maret, Norbert Telmon, Ove A. Peters, B. Lepage, J. Treil, J. M. Inglèse, A. Peyre, Jean-Luc Kahn, Michel Sixou

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OBJECTIVES: The various types of cone beam CT (CBCT) differ in several technical characteristics, notably their spatial resolution, which is defined by the acquisition voxel size. However, data are still lacking on the effects of voxel size on the metric accuracy of three-dimensional (3D) reconstructions. This study was designed to assess the effect of isotropic voxel size on the 3D reconstruction accuracy and reproducibility of CBCT data.

METHODS: The study sample comprised 70 teeth (from the Institut d'Anatomie Normale, Strasbourg, France). The teeth were scanned with a KODAK 9500 3D® CBCT (Carestream Health, Inc., Marne-la-Vallée, France), which has two voxel …

Periodontal Ligament And Gingival Fibroblasts Participate In The Production Of Tgf-Β, Interleukin (Il)-8 And Il-10, Ana Carolina Morandini, Carla Renata Sipert, Erivan Schnaider Ramos-Junior, Daniel Thomas Brozoski, Carlos Ferreira Santos

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The aim of this study was to quantify and compare the production of transforming growth factor beta (TGF-β), interleukin (IL)-8 and IL-10 by human cultured periodontal ligament and gingival fibroblasts both obtained from the same donors challenged with lipopolysaccharide (LPS) from Porphyromonas gingivalis. Fibroblasts were exposed to 0.1-10 µg/mL of LPS from P. gingivalis and after 24 h the supernatants were collected and analyzed by enzyme-linked immunosorbent assay (ELISA). TGF-β protein production was upregulated in a concentration-dependent manner, mainly in gingival fibroblasts, which was statistically significant when challenged by 10 µg/mL LPS. Additionally, at this concentration, gingival fibroblasts had almost …

D-4f, An Apoa-1 Mimetic, Decreases Airway Hyperresponsiveness, Inflammation, And Oxidative Stress In A Murine Model Of Asthma, S. D. Nandedkar, D. Weihrauch, H. Xu, Y. Shi, T. Feroah, W. Hutchins, D. A. Rickaby, Nejat Düzgüneş, C. A. Hillery, K. S. Konduri, K. A. Pritchard

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Asthma is characterized by oxidative stress and inflammation of the airways. Although proinflammatory lipids are involved in asthma, therapies targeting them remain lacking. Ac-DWFKAFYDKVAEKFKEAFNH2 (4F) is an apolipoprotein (apo)A-I mimetic that has been shown to preferentially bind oxidized lipids and improve HDL function. The objective of the present study was to determine the effects of 4F on oxidative stress, inflammation, and airway resistance in an established murine model of asthma. We show here that ovalbumin (OVA) -sensitization increased airway hyperresponsiveness, eosinophil recruitment, and collagen deposition in lungs of C57BL/6J mice by a mechanism that could be reduced by 4F. OVA …

Pick1 Deficiency Causes Male Infertility In Mice By Disrupting Acrosome Formation, Nan (Tori) Xiao, Chuen Kam, Chong Shen, Wenying Jin, Junqi Wang, Kwong Man Lee, Liwen Jiang, Jun Xia

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Protein interacting with C kinase 1 (PICK1) is a peripheral membrane protein involved in protein trafficking, a function that has been well characterized in neurons. Here, we report that male mice deficient in PICK1 are infertile and have a phenotype resembling the human disease globozoospermia. The primary defect in the testes of Pick1-knockout mice was fragmentation of acrosomes in the early stages of spermiogenesis. This fragmentation was followed by defects in nuclear elongation and mitochondrial sheath formation, leading to round-headed sperm, reduced sperm count, and severely impaired sperm motility. We found that PICK1 interacted with Golgi-associated PDZ- and coiled-coil motif-containing …

Transferrin Lipoplex-Mediated Suicide Gene Therapy Of Oral Squamous Cell Carcinoma In An Immunocompetent Murine Model And Mechanisms Involved In The Antitumoral Response, S. Neves, Henrique Faneca, S. Bertin, Krystyna Konopka, Nejat Düzgüneş, V. Pierrefite-Carle, S. Simões, M. C. Pedroso De Lima

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Suicide gene therapy has been used for the treatment of a variety of cancers. We reported previously the in vitro efficacy of the Herpes Simplex Virus Thymidine kinase (HSV-tk)/ganciclovir (GCV) system to mediate cytotoxicity in oral squamous cancer cells, using transferrin (Tf)-lipoplexes, prepared from cationic liposomes composed of 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP) and cholesterol. In the present study, we evaluated the antitumoral efficacy mediated by this lipoplex formulation in two suicide gene therapy strategies, HSV-tk/GCV and cytosine deaminase (CD)/5-fluorocytosine (5-FC), using a syngeneic, orthotopic murine model for head and neck squamous cell carcinoma. The cellular and molecular events associated with the …

Correlation Between The Levels Of Survivin And Survivin Promoter-Driven Gene Expression In Cancer And Non-Cancer Cells, Krystyna Konopka, Christopher Spain, Allison Yen, Nathan Overlid, Senait Gebremedhin, Nejat Düzgüneş

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Survivin, a member of the inhibitor of apoptosis (IAP) protein family, is associated with malignant transformation and is over-expressed in most human tumors. Using lipoplex-mediated transfection, we evaluated the activity of the reporter enzyme, luciferase, expressed from plasmids encoding the enzyme under the control of either the cytomegalovirus (CMV) or survivin promoters, in tumor- and non-tumor-derived human and murine cells. We also examined whether there is a correlation between the survivin promoter-driven expression of luciferase and the level of endogenous survivin. Human cancer cells (HeLa, KB, HSC-3, H357, H376, H413), oral keratinocytes, GMSM-K, and chemically immortalized human mammary cells, 184A-1, …

Enzastaurin, An Inhibitor Of Pkc Beta, Enhances Antiangiogenic Effects And Cytotoxicity Of Radiation Against Endothelial Cells., Aaron C. Spalding, Benjamin David Zeitlin, Kari Wilder-Romans, Mary Ellen Davis, Jacques E. Nör, Theodore S. Lawrence, Edgar Ben-Josef

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PURPOSE: Angiogenesis plays an important role in pancreas cancer pathobiology. Pancreatic tumor cells secrete vascular endothelial growth factor (VEGF), activating endothelial cell protein kinase C beta (PKC beta) that phosphorylates GSK3 beta to suppress apoptosis and promote endothelial cell proliferation and microvessel formation. We used Enzastaurin (Enz) to test the hypothesis that inhibition of PKC beta results in radiosensitization of endothelial cells in culture and in vivo. MATERIALS/METHODS: We measured PKC beta phosphorylation, VEGF pathway signaling, colony formation, and capillary sprout formation in primary human dermal microvessel endothelial cells (HDMECs) after Enz or radiation (RT) treatment. Microvessel density and tumor …

Expanding Circle Of Inhibition: Small-Molecule Inhibitors Of Bcl-2 Asanticancer Cell And Antiangiogenic Agents, Benjamin David Zeitlin, Isaac J. Zeitlin, Jacques E. Nör

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The specific targeting of diseases, particularly cancer, is a primary aim in drug development, as specificity reduces unwelcome effects on healthy tissue and increases drug efficacy at the target site. Drug specificity can be increased by improving the delivery system or by selecting drugs with affinity for a molecular ligand specific to the disease state. The role of the prosurvival Bcl-2 protein in maintaining the normal balance between apoptosis and cellular survival has been recognized for more than a decade. Bcl-2 is vital during development, much less so in adults. It has also been noted that some cancers evade apoptosis …

Longitudinal Evaluation Of Prostaglandin E2 (Pge2) And Periodontal Status In Hiv+ Patients, Tamer Alpagot, John Remien, Mouchumi Bhattacharyya, Krystyna Konopka, William Lundergan, Nejat Düzgüneş

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The study aim was to determine whether prostaglandin E2 (PGE2) in gingival crevicular fluid (GCF) could serve as a risk factor for periodontitis in human immunodeficiency virus-positive (HIV+) patients. Clinical measurements, including gingival index (GI), plaque index, bleeding index, probing depth (PD), attachment loss (AL) and GCF samples were taken from two healthy sites (including sites with gingival recession, GI = 0; PD ≤ 3 mm; AL ≤ 2 mm), three gingivitis sites (GI > 0; PD ≤ 3 mm; AL = 0) and three periodontitis sites (GI > 0; PD ≥ 5 mm; AL ≥ 3 mm) of each of the …

Serum Decreases The Size Of Metafectene- And Genejammer-Dna Complexes But Does Not Affect Significantly Their Transfection Activity In Sccvii Murine Squamous Cell Carcinoma Cells, Krystyna Konopka, Nathan Overlid, Anitha C. Nagaraj, Nejat Düzgüneş

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Cationic liposome-DNA (lipoplexes) or polymer-DNA (polyplexes) complexes have been used to deliver therapeutic genes, both in vitro and in vivo. However, gene transfer by these non-viral vectors is usually inhibited by biological milieu. A relatively high efficiency of transfection could be achieved in human oral cancer cells transfected with the polycationic liposome, Metafectene, and the polyamine reagent, GeneJammer, in the presence of 60% fetal bovine serum (FBS) (Konopka et al., Cell. Mol. Biol. Lett. 10 (2005) 455-470). Here, we examined the efficacy of these vectors to deliver β-galactosidase (β-gal), luciferase and Herpes Simplex Virus thymidine kinase (HSV-tk) genes to SCCVII …

On The Formulation Of Ph-Sensitive Liposomes With Long Circulation Times, Sérgio Simões, João Nuno Moreira, Cristina Fonseca, Nejat Düzgüneş, Maria C. Pedroso De Lima

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Strategies used to enhance liposome-mediated drug delivery in vivo include the enhancement of stability and circulation time in the bloodstream, targeting to specific tissues or cells, and facilitation of intracytoplasmic delivery. pH-sensitive liposomes have been developed to mediate the introduction of highly hydrophilic molecules or macromolecules into the cytoplasm. These liposomes destabilize under acidic conditions found in the endocytotic pathway, and usually contain phosphatidylethanolamine (PE) and titratable stabilizing amphiphiles. Formulations without PE have also been developed. Encapsulated compounds are thought to be transported into the cytoplasm through destabilization of or fusion with the endosome membrane. Incorporation of a low mole …

The Shape Parameter Of Liposomes And Dna-Lipid Complexes Determined By Viscometry Utilizing Small Sample Volumes, Yan Sun, X. Li, Nejat Düzgüneş, Y. Takaoka, S. Ohi, S. Hirota

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A minicapillary viscometer utilizing <0.5 ml of sample at a volume fraction of <0.1% is described. The calculated a/b of DPPC/DPPG multilamellar liposome was 1.14 as prolate ellipsoids and a/b of dioleoylpropyltrimethyl ammonium methylsulfate-DNA complex at a charge ratio of 4:1 (+/-) was 3.7 as prolate ellipsoids or 4.9 as oblate ellipsoids. The deviation of shape from perfect sphere is thus expressed quantitatively in more than two significant figures. In these measurement, the necessary amount of DNA is <0.5 mg.

Increased Receptor-Mediated Gene Delivery To The Liver By Protamine-Enhanced-Asialofetuin-Lipoplexes, M. A. Arangoa, Nejat Düzgüneş, C. Tros De Ilarduya

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A novel lipidic vector composed of DOTAP/Chol liposomes, asialofetuin (AF), protamine sulfate and DNA has been developed. The resulting protamine-AF-lipoplexes improved significantly the levels of gene expression in cultured cells and in the liver upon i.v. administration. Lipoplexes containing the optimal amount of AF (1 μg/μg DNA) showed a 16-fold higher transfection activity in HepG2 cells than non-targeted (plain) complexes. The uptake by cells having asialoglycoprotein receptors (ASGPr) on their plasma membrane was decreased by the addition of free AF, indicating that AF-lipoplexes were taken up specifically by cells via ASGPr-mediated endocytosis. Results from transfections performed in cells defective in …

Enhanced Gene Delivery In Vitro And In Vivo By Improved Transferrin-Lipoplexes, Conchita Tros De Ilarduya, M. A. Arangoa, M. J. Moreno-Aliaga, Nejat Düzgüneş

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Cationic liposomes and the complexes they form with DNA (lipoplexes) constitute the most promising alternative to the use of viral vectors for gene therapy. One of the limitations to their application in vivo, however, is the inhibition of gene delivery by serum. In a previous study, we demonstrated that transferrin (Tf)-lipoplexes were superior to plain lipoplexes in transfecting HeLa cells in the presence of high concentrations of serum. With the goal of obtaining efficient gene expression in vivo, we evaluated the efficacy of Tf-lipoplexes (containing DOTAP and cholesterol) in transfecting primary hepatocytes and adipocytes in the presence of high serum …

Fluorescent Probes For Monitoring Virus Fusion Kinetics: Comparative Evaluation Of Reliability, Isabel Nunes-Correia, Ana Eulálio, Shlomo Nir, Nejat Düzgüneş, João Ramalho-Santos, Maria C. Pedroso De Lima

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Fluorescence assays for viral membrane fusion employ lipidic probes whose kinetics of fluorescence dequenching should mimic the actual kinetics of membrane merging. We examined the fusion of influenza virus with CEM cells, erythrocyte ghosts or liposomes by monitoring the fluorescence dequenching of each one of the three probes, octadecylrhodamine B chloride (R18), N-(lissamine rhodamine B sulfonyl)phosphatidylethanolamine (Rh-PE), or rac-2,3-dioleoylglycerol ester of rhodamine B (DORh-B), inserted into the virus membrane. Experimental conditions were designed to allow a clear distinction between membrane mixing and non-specific probe transfer. Fluorescence dequenching observed with Rh-PE was much slower than with R18, unless a particular experimental …

On The Mechanisms Of Internalization And Intracellular Delivery Mediated By Ph-Sensitive Liposomes, Sérgio Simões, Vladimir Slepushkin, Nejat Düzgüneş, Maria C. Pedroso De Lima

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We investigated the molecular mechanisms by which pH-sensitive liposomes surpass the cytoplasmic and endosomal membranes to deliver their aqueous contents into the cytoplasm. Various liposome formulations were evaluated for their efficacy to mediate intracellular delivery of encapsulated material, including a novel sterically stabilized pH-sensitive formulation ((DOPE:CHEMS:DSPE-PEG2000 (6:4:0.3)) that was previously developed in our laboratories. In an attempt to fully characterize the nature of liposome-cell interactions different approaches based on a dual-labeling fluorescence assay were used. Our results indicate that the efficacy of interaction of pH-sensitive liposomes, both plain and sterically stabilized, with cells is strongly determined by the inclusion of …

Human Serum Albumin Enhances Dna Transfection By Lipoplexes And Confers Resistance To Inhibition By Serum, Sérgio Simões, Vladimir Slepushkin, Pedro Pires, Rogério Gaspar, Maria C. Pedroso De Lima, Nejat Düzgüneş

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Cationic liposome-DNA complexes ('lipoplexes') are used as gene delivery vehicles and may overcome some of the limitations of viral vectors for gene therapy applications. The interaction of highly positively charged lipoplexes with biological macromolecules in blood and tissues is one of the drawbacks of this system. We examined whether coating cationic liposomes with human serum albumin (HSA) could generate complexes that maintained transfection activity. The association of HSA with liposomes composed of 1,2-dioleoyl-3-(trimethylammonium) propane and dioleoylphosphatidylethanolamine, and subsequent complexation with the plasmid pCMVluc greatly increased luciferase expression in epithelial and lymphocytic cell lines above that obtained with plain lipoplexes. The …

Efficient Gene Transfer By Transferrin Lipoplexes In The Presence Of Serum, Conchita Tros De Ilarduya, Nejat Düzgüneş

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Cationic lipids are being used increasingly as reagents for gene delivery both in vitro and in vivo. One of the limitations to the application of cationic lipid-DNA complexes (lipoplexes) in vivo is the inhibition of gene delivery by serum. In this study, we have shown that transferrin (Tf)-lipoplexes, which had transferrin adsorbed at their surface via electrostatic interactions, are much more effective than plain lipoplexes in transfecting cells in the presence of relatively high concentrations (up to 60%) of fetal bovine serum (FBS). Serum even enhanced transfection by Tf-lipoplexes composed of 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP)/dioleoylphosphatidylethanolamine (DOPE)/pCMVLacZ at high lipid/DNA (+/-) charge …

Mechanisms Of Gene Transfer Mediated By Lipoplexes Associated With Targeting Ligands Or Ph-Sensitive Peptides, Sérgio Simões, Vladimir Slepushkin, Pedro Pires, Rogério Gaspar, Maria C. Pedroso De Lima, Nejat Düzgüneş

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Association of a targeting ligand such as transferrin, or an endosome disrupting peptide such as GALA, with cationic liposome-DNA complexes ('lipoplexes') results in a significant enhancement of transfection of several cell types. Although these strategies can overcome some of the barriers to gene delivery by lipoplexes, the mechanisms by which they actually enhance transfection is not known. In studies designed to establish the targeting specificity of transferrin, we found that apo-transferrin enhances transfection to the same extent as transferrin, indicating that internalization of the lipoplexes is mostly independent of transferrin receptors. These observations were reinforced by results obtained from competitive …

Interaction Of Cationic Liposomes And Their Dna Complexes With Monocytic Leukemia Cells, Pedro Pires, Sérgio Simões, Shlomo Nir, Rogério Gaspar, Nejat Düzgüneş, Maria C. Pedroso De Lima

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Cationic liposomes complexed with DNA have been used extensively as non-viral vectors for the intracellular delivery of reporter or therapeutic genes in culture and in vivo. We examined the relationship between the characteristics of the lipoplexes, their mode of interaction with monocytic THP-1 cells and their ability to transfect these cells. We determined the size and ζ potential of cationic liposomes (composed of 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP) and its mixtures with neutral lipids), and lipoplexes at different (+/-) charge ratios. As the (+/-) charge ratio of the lipoplexes decreased to (1/1), a significant reduction in ζ potential and an increase in …

Transfection Of Human Macrophages By Lipoplexes Via The Combined Use Of Transferrin And Ph-Sensitive Peptides, Sérgio Simões, Vladimir Slepushkin, Elizabeth Pretzer, Paul Dazin, Rogério Gaspar, Maria C. Pedroso De Lima, Nejat Düzgüneş

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The crucial function of macrophages in a variety of biological processes and pathologies render these cells important targets for gene therapeutic interventions. Commonly used synthetic gene delivery vectors have not been successful in transfecting these non-dividing cells. A combination strategy involving cationic liposomes to condense and carry DNA, transferrin to facilitate cellular uptake, and the pH-sensitive peptide GALA to promote endosome destabilization, resulted in significant expression of a luciferase gene. Transfection of macrophages was dependent on the degree of differentiation of the cells. The quaternary complexes of cationic liposomes, DNA, transferrin, and GALA exhibited a net negative charge, which may …

Delivery Of An Anti-Hiv-1 Ribozyme Into Hiv-Infected Cells Via Cationic Liposomes, Krystyna Konopka, John J. Rossi, Piotr Swiderski, Vladimir A. Slepushkin, Nejat Düzgüneş

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Cationic liposome-mediated intracellular delivery of a fluorescein-labeled chimeric DNA-RNA ribozyme targeted to the HIV-1 5' LTR was investigated, using THP-1, THP-1/HIV-1(IIIB) or HeLa/LAV cells. Different fluorescence patterns were observed when the cells were exposed to Lipofectamine, Lipofectin or DMRIE:DOPE (1:1) complexed to the ribozyme. With Lipofectamine intense cell-associated fluorescence was found. Incubation with Lipofectin resulted in less intense diffuse fluorescence, while with DMRIE an intense but sporadic fluorescence was observed. Differentiated THP-1/HIV-1(IIIB) cells were more susceptible to killing by liposome-ribozyme complexes than THP-1 cells. Under non-cytotoxic conditions (a 4-h treatment) complexes of 5, 10 or 15 μM Lipofectin or DOTAP:DOPE …

Gene Delivery By Negatively Charged Ternary Complexes Of Dna, Cationic Liposomes And Transferrin Or Fusigenic Peptides, Sérgio Simões, Vladimir Slepushkin, R. Caspar, Maria C. Pedroso De Lima, Nejat Düzgüneş

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Potential problems with the use of viral vectors for gene therapy necessitate the development of efficient nonviral vectors. The association of transferrin, or the pH-sensitive peptide GALA, with cationic liposomes composed of 1,2-dioleoyl-3-(trimethylammonium) propane and its equimolar mixture with dioleoylphosphatidylethanolamine, under conditions where the liposome/DNA complex is negatively charged, drastically increased luciferase expression from pCMVluc. The percentage of cells transfected, measured by β-galactosidase expression, was also increased by about 10-fold. The zeta potential of the ternary complexes was lower than that of the liposome/DNA complexes. Transfection activity of positively charged complexes was also enhanced by association with transferrin, GALA or …

Cationic Liposome-Mediated Expression Of Hiv-Regulated Luciferase And Diphtheria Toxin A Genes In Hela Cells Infected With Or Expressing Hiv, Krystyna Konopka, Gail S. Harrison, Philip L. Felgner, Nejat Düzgüneş

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HIV-regulated expression of the diphtheria toxin A fragment gene (HIV-DT-A) is a potential gene therapy approach to AIDS. Since cationic liposomes are safe and non-immunogenic for in vivo gene delivery, we examined whether LipofectAMINE or DMRIE reagent could mediate the transfection of HIV-DT-A (pTHA43) or the HIV-regulated luciferase gene (pLUCA43) into HIV-infected or uninfected HeLa cells. pLUCA43 was expressed at a 103-fold higher level in HeLa/LAV cells than in uninfected HeLa cells, while the extent of expression of RSV-regulated luciferase was the same in both cell lines. Co-transfection of HeLa cells with pTHA43 and the proviral HIV clone, HXBΔBgl, resulted …

Sterically Stabilized Ph-Sensitive Liposomes. Intracellular Delivery Of Aqueous Contents And Prolonged Circulation In Vivo, Vladimir A. Slepushkin, Sérgio Simões, Paul Dazin, Mary S. Newman, Luke S. Guo, Maria C. Pedroso De Lima, Nejat Düzgüneş

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Liposomes that destabilize at mildly acidic pH are efficient tools for delivering water-soluble drugs into the cell cytoplasm. However, their use in vivo is limited because of their rapid uptake from circulation by the reticuloendothelial system. Lipid-anchored polyethylene glycol (PEG-PE) prolongs the circulation time of liposomes by steric stabilization. We have found that addition of PEG-PE to the membrane of pH-sensitive liposomes composed of cholesteryl hemisuccinate (CHEMS) and dioleoylphosphatidylethanolamine (DOPE) confers steric stability to these vesicles. This modification significantly decreases the pH-dependent release of a charged water-soluble fluorophore, calcein, from liposomes suspended in buffer or cell culture medium. However, the …

Human Immunodeficiency Virus Type-1 (Hiv-1) Infection Increases The Sensitivity Of Macrophages And Thp-1 Cells To Cytotoxicity By Cationic Liposomes, Krystyna Konopka, Elizabeth Pretzer, Philip L. Felgner, Nejat Düzgüneş

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Cationic liposomes may be valuable for the delivery of anti-sense oligonucleotides, ribozymes, and therapeutic genes into human immunodeficiency virus type 1 (HIV-1)-infected and uninfected cells. We evaluated the toxicity of three cationic liposomal preparations, Lipofectamine, Lipofectin, and 1,2-dimyristyloxypropyl-3-dimethyl-hydroxyethyl ammonium bromide (DMRIE) reagent, to HIV-infected and uninfected cells. Monocyte/macrophages were infected with HTV-1(BaL) and treated with liposomes in medium containing 20% fetal bovine serum (FBS) for 4 h or 24 h at 37°C. Uninfected monocytic THP-1 cells and chronically infected THP-1/HIV-1(IIIB) cells were treated with phorbol 12-myristate 13-acetate (PMA) and exposed to liposomes in the presence of 10% FBS. Toxicity was …

Treatment Of Intracellular Mycobacterium Avium Complex Infection By Free And Liposome-Encapsulated Sparfloxacin, Nejat Düzgüneş, Diana L. Flasher, M. Venkata Reddy, Julieta Luna-Herrera, Pattisapu R.J. Gangadharam

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Mycobacterium avium-M. intracellulare complex (MAC) is the most frequent cause of opportunistic bacterial infection in patients with AIDS. Previous studies have indicated that liposome-encapsulated aminoglycosides are highly effective in treating MAC infections in mice. We investigated whether the fluoroquinolone sparfloxacin is effective in treating MAC infection in the murine macrophage-like cell line J774. Sparfloxacin was encapsulated in the membrane phase of multilamellar liposomes composed of phosphatidylglycerol-phosphatidylcholine-cholesterol (1:1:1 molar ratio). MAC-infected macrophages were treated for either 24 h or 4 days with free or liposome-encapsulated sparfloxacin. Treatment with free or liposome- encapsulated sparfloxacin (6 μg/ml) for 24 h resulted in the …

Target Cell Membrane Sialic Acid Modulates Both Binding And Fusion Activity Of Influenza Virus, Maria C. Pedroso De Lima, João Ramalho-Santos, Diana L. Flasher, Vladimir A. Slepushkin, Shlomo Nir, Nejat Düzgüneş

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Influenza virus binds to cell surface sialic acid receptors, and following endocytosis fuses with the endosome membrane at low pH. Whether sialic acid plays a role in the virus-cell membrane fusion step is not known. We investigated the effect of the removal of cell membrane sialic acid on the fusion activity of influenza virus (A/PR/8/34 strain) toward human T lymphocytic leukemia (CEM) cells at low pH. Fusion was monitored by fluorescence dequenching of octadecylrhodamine incorporated in the virus membrane. Removal of sialic acid by neuraminidase resulted in a drastic reduction in both viral binding and fusion. The association of the …

A Monoclonal Antibody To The Gp120-Cd4 Complex Has Differential Effects On Hiv-Induced Syncytium Formation And Viral Infectivity, Krystyna Konopka, Elizabeth Pretzer, F. Celada, Nejat Düzgüneş

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A murine monoclonal antibody (MAb F-91-55) raised against the complex of soluble CD4 and human immunodeficiency virus type 1 (HIV-1) gp120 had previously been found to inhibit syncytium formation without inhibiting the interaction of CD4 with gp120, and its binding site was localized within the first two domains (D1/D2) of CD4. We investigated whether this antibody inhibited the infectivity of HIV-1 in the CD4+ T cell lines A3.01, Sup-T1 and H9. We also examined the effect of the antibody on syncytium formation between these cells and chronically infected H9 cells. Syncytium formation was found to depend critically on the incubation …

Therapy Of Mycobacterium Avium Complex Infections In Beige Mice With Streptomycin Encapsulated In Sterically Stabilized Liposomes, Pattisapu R.J. Gangadharam, D. R. Ashtekar, Diana L. Flasher, Nejat Düzgüneş

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Mycobacterium avium complex (MAC) causes serious opportunistic infections in AIDS patients. Previous studies with MAC-infected beige mice have indicated that weekly administration of liposome-encapsulated streptomycin can reduce significantly the CFU in the liver and spleen. We examined whether streptomycin encapsulated in recently developed sterically stabilized liposomes with prolonged circulation times would have a therapeutic effect in this animal model. Two liposome types with prolonged circulation (polyethyleneglycol-distearoylphosphatidylethanolamine [PEG-DSPE]- distearoylphosphatidylcholine [DSPC]-cholesterol [chol] or phosphatidylinositol [PI]-DSPC-chol) and conventional liposomes (phosphatidylglycerol [PG]-phosphatidylcholine [PC]-chol) encapsulating streptomycin and administered twice weekly were bactericidal to MAC strain 101 in the spleen when the level of infection after …