Search PubMed⌕ Search

Biomedical subjects

Theodore Friedmann

Publications and source records attributed to Theodore Friedmann.

8 recordsLinked to original sources
PubMed2005

Baculovirus GP64-pseudotyped HIV-based lentivirus vectors are stabilized against complement inactivation by codisplay of decay accelerating factor (DAF) or of a GP64-DAF fusion protein.

The eventual development of efficient gene transfer vectors for in vivo gene delivery will require the development of a number of important new technologies such as stabilization of vectors against protective mechanisms that destroy or otherwise inactivate foreign infectious agents like gene transfer vectors. It is known that the baculovirus envelope protein GP64 of Autographa californica nucleopolyhedrovirus can efficiently pseudotype lentivirus vectors and that modified forms of the baculovirus envelope protein GP64 can also assemble efficiently into baculovirus particles to display functional foreign proteins on the baculovirus surface. In the present study we have combined these techniques to prepare HIV-based lentivirus vectors pseudotyped with GP64 envelope protein and coexpressing a fusion protein of GP64 with the complement-regulatory, decay accelerating factor (DAF, CD55). In addition, we have also prepared GP64-pseudotyped vectors in the presence of a DAF expression plasmid to allow the incorporation of DAF protein into viral particles. Our results demonstrate both the efficient expression and the high-titer production of GP64/GP64-DAF and GP64/DAF-pseudotyped particles and their stability against inactivation by human and nonhuman primate serum.

CD55 Antigens↗
PubMed2004

Discrepant effects of culture conditions on survival and function of dopaminergic neurons.

Primary midbrain cultures are valuable for probing the function of dopaminergic neurons and for elucidating the factors that cause their dysfunction and degeneration. To allow more effective control of the culture environment, we have characterized the survival, differentiation, and trophic factor response of dopaminergic neurons in the absence of serum. Combinations of media and supplements markedly affected all three indices measured. Combinations that produced maximal dopaminergic neuron survival are different from those that result in maximal differentiation and trophic factor response. Furthermore, antioxidant treatment was effective with only one medium/supplement combination, indicating that these neurons were not degenerating as a result of oxidative stress in the majority of culture conditions used in this study. These results demonstrate that dopaminergic neurons can be grown in serum-free conditions but that the choice of culture conditions has a marked influence on cell survival and function.

Animals↗
PubMed2004

Ligand-modified vesicular stomatitis virus glycoprotein displays a temperature-sensitive intracellular trafficking and virus assembly phenotype.

The production of potentially targetable VSV-G-pseudotyped retrovirus vectors has been hampered by inadequate understanding of the structure-function relationships of the VSV-G protein. In these studies we demonstrate assembly and production of MLV-based and HIV-1-based vector particles using VSV-G proteins modified by the insertion of a peptide ligand into a site corresponding to amino acid position 24 of the native VSV-G molecule. The inserted ligand represents the decapeptide encoding the collagen-binding domain of von Willebrand factor. We have used deconvolution microscopy to demonstrate that the modified VSV-G molecules sequester in perinuclear structures and are unavailable for assembly of infectious virus particles at the cell surface under standard tissue culture conditions at 37 degrees C. In contrast, at a lower permissive temperature of 30 degrees C, the modified VSV-G protein traffics appropriately to the cell surface and participates in useful titers. Furthermore, VSV-G-pseudotyped MLV-based and HIV-1-based vectors displaying the collagen-binding domain demonstrate a statistically significant increased attachment to a collagen matrix as indicated by an ELISA-like cell binding assay and by a focus transduction assay.

Amino Acid Sequence↗
PubMed2003

Plus ça change...

Explore the source record for details and available documents.

Advisory Committees↗
PubMed2002

Oxidative stress and dopamine deficiency in a genetic mouse model of Lesch-Nyhan disease.

Lesch-Nyhan disease, a neurogenetic disorder caused by congenital deficiency of the purine salvage enzyme hypoxanthine guanine phosphoribosyl transferase, is associated with a prominent loss of striatal dopamine. The current studies address the hypothesis that oxidant stress causes damage or dysfunction of nigrostriatal dopamine neurons in a knockout mouse model of the disease, by assessing several markers of oxidative damage and free radical scavenging systems. Some of these measures provided evidence for an increase in oxidative stress in the mutant mice (aconitase activity, oxidized glutathione, and lipid peroxides), but others did not (superoxide dismutase, protein thiol content, carbonyl protein content, total glutathione, glutathione peroxidase, catalase, and thiobarbituric reducing substances). Immunolocalization of heme-oxygenase 1 provided no evidence for oxidative stress restricted to specific elements of the striatum or midbrain in the mutants. Striatal dopamine systems of the mutant mice were more vulnerable to a challenge with the neurotoxin 6-hydroxydopamine, but they were not protected by cross-breeding the mutants with transgenic mice over-expressing superoxide dismutase. Overall, these data provide evidence for increased oxidative stress, but the failure to protect the knockout mice by over-expressing SOD1 argues that oxidative stress is not the sole process responsible for the loss of striatal dopamine.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2002

Cell surface heparan sulfate is a receptor for attachment of envelope protein-free retrovirus-like particles and VSV-G pseudotyped MLV-derived retrovirus vectors to target cells.

Non-infectious, envelope protein-free, retrovirus-like particles (VLP) derived from either Moloney murine leukemia virus (MLV) or human HIV are able to bind efficiently to, but not infect, target cells. Upon subsequent addition to the bound particles of the G protein of vesicular stomatitis virus (VSV-G), an efficient surrogate retrovirus envelope protein, the VLP are efficiently taken up by the cells to produce infection. Cell attachment of the VLP is efficiently inhibited by soluble heparin and dextran sulfate and less efficiently abrogated by several other glycosaminoglycans (GAGs) including chondroitin sulfate A and chondroitin sulfate B (dermatan sulfate), as determined by deconvolution microscopic immunodetection of the viral gag protein and by quantitative binding studies of metabolically labeled (35)S-VLP. Enzymatic digestion of heparan sulfate (HS) from the cell surface with heparinase I also reduces VLP binding. Furthermore, VLP adsorption onto several CHO cell lines variably deficient in cell surface GAG is significantly but incompletely abrogated. De-sulfated heparins are less efficient than native heparin in inhibiting the Polybrene-mediated binding of VLP, whereas growth of human cells in the presence of sodium chlorate leads to significant reduction of Polybrene-mediated VLP binding. In addition, specific inhibition of VLP binding and infectivity of mature infectious VSV-G-pseudotyped virus is observed in the presence of heparin and HS under Polybrene-free conditions. We conclude from these studies that the presence of Polybrene, the degree of sulfation of cell surface GAG, and possibly the presence of charged cell surface macromolecules create an electrostatic environment that promotes optimum binding of VLP to cells. Additionally, our results demonstrate that, in the absence of Polybrene, initial attachments of non-infectious, envelope protein-free VLP and probably mature infectious virus particles are mediated by interactions of the virus particles with cell surface heparan sulfate, and possibly with other GAG molecules.

Animals↗