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Biomedical subjects

J M Wilson

Publications and source records attributed to J M Wilson.

At least 199 records · Page 11Linked to original sources
PubMed1997

Recombinant adeno-associated virus for muscle directed gene therapy.

Although gene transfer with adeno-associated virus (AAV) vectors has typically been low, transduction can be enhanced in the presence of adenovirus gene products through the formation of double stranded, non-integrated AAV genomes. We describe the unexpected finding of high level and stable transgene expression in mice following intramuscular injection of purified recombinant AAV (rAAV). The rAAV genome is efficiently incorporated into nuclei of differentiated muscle fibers where it persists as head-to-tail concatamers. Fluorescent in situ hybridization of muscle tissue suggests single integration sites. Neutralizing antibody against AAV capsid proteins does not prevent readministration of vector. Remarkably, no humoral or cellular immune responses are elicited to the neoantigenic transgene product E. coli beta-galactosidase. The favorable biology of rAAV in muscle-directed gene therapy described in this study expands the potential of this vector for the treatment of inherited and acquired diseases.

Animals↗
PubMed1997

Adenovirus-mediated gene transfer by perivitelline microinjection of mouse, rat, and cow embryos.

To determine the fate of an episomally expressed transgene, mouse, rat, and cow zygotes were injected into the perivitelline space with approximately 100 pl of buffer containing the replication-defective human adenovirus, AdCMVLacZ/sub360. Viral concentrations ranged from 2.5 to 2.5 x 10(5) plaque-forming units (pfu)/100 pl. As viral titer increased, fewer embryos were able to develop to blastocysts. In the mouse, the percentage of blastocysts formed ranged from 82% in controls to 16% after injection at the highest titer. In the rat and cow, a similar decrease in blastocyst formation was noted (62% to 6% and 26% to 4%, respectively). Reporter gene (galactosidase, LacZ) activity could be detected in mouse embryos after injection at a concentration of only 25 pfu/100 pl, whereas a tenfold higher titer was required in the other two species to observe the blue LacZ reaction product. When examined after 5 (mouse), 6 (rat), or 9 (cow) days of in vitro culture, the proportion of LacZ-positive embryos ranged from 15% to 96%, 6% to 76%, and 18% to 58% in mouse, rat, and cow embryos, respectively, depending upon viral concentration. However, a large percentage of positive embryos proved to be expression mosaics, the degree of which was likewise dependent on titer. While none of the embryos showed LacZ activity at 30 h after injection, 70% of mouse, 8% of rat, and 20% of cow embryos expressed the reporter gene at 42 h. Delaying the timing of injection revealed that the efficiency with which mouse and rat embryos could be infected decreased with increasing degree of differentiation. Only 35% and 18% of mouse embryos expressed the reporter gene after injection at the morula or blastocyst stage, respectively. A similar drop in efficiency was noted in rat embryos when injections took place at the 8-cell, morula, or blastocyst stage, with 70%, 33%, and 9% of embryos, respectively, subsequently showing LacZ activity. Likewise, advanced development resulted in a decrease in the efficiency of viral-mediated gene transfer in cow embryos, with 100%, 78%, and 68% of embryos being positive after injection at the 8-cell, morula, or blastocyst stage, respectively. These results demonstrate that a human adenovirus can be used to express a reporter gene transiently in nonhuman embryos.

Adenoviridae↗
PubMed1997

Treatment of equine oocytes with A23187 after intracytoplasmic sperm injection.

In vitro matured horse oocytes with a first polar body (n = 68) were each injected with a single spermatozoon and divided into 2 groups: Group 1 oocytes were treated with 10 microM calcium ionophore A23187 for 5 min while Group 2 oocytes received no activation treatment. After culture in vitro for 2 days, significantly more oocytes treated with A23187 (5/24, 21%) cleaved than oocytes without activation treatment (2/44, 5%, P<0.05). All 7 cleaved zygotes from both treatment groups were transferred to recipient mares but no pregnancies resulted.

Animals↗
PubMed1997

Adenovirus-mediated in vivo gene transfer rapidly protects ornithine transcarbamylase-deficient mice from an ammonium challenge.

The purpose of this study was to determine the time of onset, duration, and the efficacy of in vivo gene transfer in protecting the ornithine transcarbamylase deficient spf/Y mouse from an acute ammonium challenge. The animals were challenged with ammonia (10 mmol/kg NH4Cl) 1, 2, 7, 14, or 28 d after the administration of a recombinant adenoviral construct deleted in E1 and with a temperature sensitive mutation in E2. Although there was no protection with the control LacZ virus, the ornithine transcarbamylase (OTC)-containing vector provided partial protection from both behavioral symptoms (ataxia, seizures, and abnormal response to sound) and biochemical abnormalities (ammonium, aspartate, alanine, and glutamine) within 24 h and complete protection by 48 h. Mortality was also decreased. Animals receiving the vector 7 and 14 d before the ammonium load were also protected, whereas those treated 28 d before the challenge were not. OTC enzyme activity in liver of untreated spf/Y mice was 5% of control C3H mice. After gene transfer, activity was increased to near control levels through 14 d but had returned to baseline by 28 d. These studies indicate that adenovirus-mediated gene transfer confers a metabolic benefit within 24 h of administration and provides protection against an acute metabolic insult for at least 2 wk.

Adenoviridae↗
PubMed1997

Vectors--shuttle vehicles for gene therapy.

Gene therapy is being considered for the treatment of various inherited and acquired disorders. The basic premise of this new therapeutic modality is manipulation of gene expression towards a therapeutic end. The early development of the field focused on a technique called ex vivo gene therapy in which autologous cells are genetically manipulated in culture prior to transplantation. Recent advances have stimulated the development of in vivo gene therapy approaches based on direct delivery of the therapeutic gene to cells in vivo. The rate-limiting technologies of gene therapy are the gene delivery vehicles, called vectors, used to accomplish gene transfer. The most efficient vectors are based on recombinant versions of viruses with retroviral vectors serving as prototypes. This viral vector system has been exploited in ex vivo approaches of gene therapy in which cultured, dividing cells are transduced with the recombinant virus resulting in integration of the proviral DNA into the chromosomal DNA of the recipient cell. The use of retroviral vectors in gene therapy has been restricted to ex vivo approaches because of difficulties in purifying the virion and the requirement that the target cell is dividing at the time of transduction. More recently, vectors based on adenoviruses have been developed for in vivo gene therapy. These viruses can be grown in large quantities and highly purified. Importantly, they efficiently transduce the recombinant genome into non-dividing cells. Applications include in vivo gene delivery to a variety of targets such as muscle, lung, liver and the central nervous system. Clinical trials of in vivo delivery with adenoviruses have been undertaken for the treatment of cystic fibrosis.

Cystic Fibrosis↗
PubMed1996

Safety of intrapleurally administered recombinant adenovirus carrying herpes simplex thymidine kinase DNA followed by ganciclovir therapy in nonhuman primates.

Preclinical safety and toxicity studies of intrapleural administration of recombinant adenovirus carrying the herpes simplex thymidine kinase gene (H5.010RSVtk) were performed. Previously reported experimental evidence has demonstrated the efficacy of this approach in animal models of a localized thoracic cancer, malignant mesothelioma. H5.010RSVtk was delivered at high dose (10(12) pfu) into the pleural cavity of three non-human primates followed by systemic administration of ganciclovir. No clinical toxicity was noted. Although an inflammatory reaction observable by microscopy was noted in the serosal spaces of the chest cavity, these changes were reversible and were not associated with radiographic sequelae. Extrathoracic viral dissemination was minimal and detectable only by sensitive polymerase chain reaction techniques. This low level of viral dissemination was not associated with detectable clinical, biochemical, or pathologic abnormalities.

Adenoviridae↗
PubMed1996

A novel adenovirus-adeno-associated virus hybrid vector that displays efficient rescue and delivery of the AAV genome.

Adenovirus and adeno-associated virus (AAV) are eukaryotic DNA viruses being developed as vectors for human gene therapy. The strengths of each system have been exploited in a novel vector that is based on an adenovirus-AAV hybrid virus incorporated into a plasmid-based molecular conjugate. Efficient rescue and replication of the recombinant AAV genome in this hybrid required transient expression of rep. This feature was incorporated into the transducing particle by conjugating a rep expression plasmid to the hybrid virus through a polylysine bridge. The resulting particle is an attractive vehicle for gene therapy because it is easily manufactured and capable of efficiently transducing cells with the end result being rescue and replication of the recombinant AAV genome. This particle is also useful in the production of recombinant AAV resulting in yields 10-fold greater than that achieved with transfection-based protocols.

Adenoviruses, Human↗
PubMed1996

In vivo expression of full-length human dystrophin from adenoviral vectors deleted of all viral genes.

Adenoviral vectors have been shown to effect efficient somatic gene transfer in skeletal muscle and thus offer potential for the development of therapy for Duchenne muscular dystrophy (DMD). Efficient transfer of recombinant genes has been demonstrated in skeletal muscle using recombinant adenoviruses deleted of E1. Application of this vector system to the treatment of DMD is limited by the vector immunogenicity, as well as by size constraints for insertion of recombinant genes, precluding the incorporation of a full-length dystrophin minigene construct. We describe in this study the use of helper adenovirus to generate a recombinant vector deleted of all viral open reading frames and containing a full-length dystrophin minigene. We show that this deleted vector (delta vector) is capable of efficiently transducing dystrophin in mdx mice, in myotubes in vitro and muscle fibers in vivo. Our modification of adenoviral vector technology may be useful for the development of gene therapies for DMD and other diseases.

Adenoviridae↗
PubMed1996

CD40 ligand-dependent T cell activation: requirement of B7-CD28 signaling through CD40.

The role of CD40 ligand (CD40L) in the primary activation of T cells is not clear. The cellular and humoral immune responses to adenoviral vectors in a murine model of liver-directed gene transfer were studied to define the mechanisms responsible for CD40L-dependent T cell priming. CD40L-deficient mice did not develop effective cytotoxic T cells to transduced hepatocytes, and T cell-dependent B cell responses were absent. Full reconstitution of cellular and humoral immunity was achieved in CD40L-deficient mice by administration of an activating antibody to CD40 that increased expression of B7.2 on spleen cells. Wild-type mice could be made nonresponsive to vector by administration of antibodies to B7. Thus, CD40L-dependent activation of T cells occurs through signaling of CD40 in the antigen-presenting cell to enhance requisite costimulatory pathways that include B7.

Adenoviridae↗
PubMed1996

The chemistry of pseudomonic acid. 17. Dual-action C-1 oxazole derivatives of pseudomonic acid having an extended spectrum of antibacterial activity.

A series of C-1 oxazole isosteres of pseudomonic acid A (mupirocin) bearing a nitroheterocycle have been synthesized, and significant differences in both spectrum of activity and potency were found between these derivatives and mupirocin. Additionally, the antibacterial potency of two members of this class of compounds against mupirocin-resistant staphylococci could not be accounted for solely by inhibition of the target enzyme isoleucyl-tRNA synthetase (IRS), indicating an additional mode of action. The most potent compound, the nitrofuran 3f (SB 205952), was the most electron affinic derivative prepared and was transformed by NAD(P)H-dependent bacterial reductases at a rate similar to that for nitrofurantoin. The second mode of action of this compound may therefore arise from its reduction to a species with cellular targets other than IRS. In in vivo studies, 3f was shown to be a very effective agent by both the subcutaneous and oral routes of administration.

Anti-Bacterial Agents↗
PubMed1996

Cyclophosphamide diminishes inflammation and prolongs transgene expression following delivery of adenoviral vectors to mouse liver and lung.

Immune responses to adenovirus-mediated gene transfer contribute to the problems of transient recombinant gene expression, inflammation, and difficulties with vector readministration. Activation of CD4+ T cells is required for full realization of effector function of both CD8+ T cells (i.e., cytotoxic T cells) and B cells (i.e., neutralizing antibody). We evaluate in this study the effectiveness of a short course of high-dose cyclophosphamide to block immune responses in mice administered vector into lung and liver of C57BL/6 mice. Administration of cyclophosphamide with vector directed to liver blocked activation and mobilization of both CD4+ and CD8+ T cells. As a result, transgene expression was prolonged, inflammation was reduced, and, at the higher doses of cyclophosphamide, formation of neutralizing antibody was prevented and the vector was successfully readministered. Similar studies in the lung demonstrated an effective blockade of T and B cell responses. In contrast to the liver, where it was easier to stabilize transgene expression than to prevent neutralizing antibody, cyclophosphamide prevented the formation of neutralizing antibodies at all doses in the lung, whereas stabilization of transgene expression was only achieved at the highest dose. These experiments begin to define the parameters by which cyclophosphamide could be used as an adjunct in gene therapy.

Adenoviridae↗
PubMed1996

Treatment of advanced CNS malignancies with the recombinant adenovirus H5.010RSVTK: a phase I trial.

Primary CNS malignancies are responsible for approximately 12,000 deaths annually in the United States. There has been little change in the outcome for adults with malignant brain tumors over the past few decades, despite improvements in surgical techniques and advances in radiation therapy. These tumors are uniformly fatal one to two years after diagnosis. The morbidity and mortality of this disease arise from the effects of a locally invasive, non-metastasizing lesion. The patients may suffer from seizures, paralysis, incoordination, aphasia, confusion, memory loss, sensory deficits or visual loss, depending on the regions of the brain affected. In addition, they usually require large doses of corticosteroids early and late in their illness, and may experience disabling side effects of this treatment, such as edema, proximal myopathy, diabetes, fungal infections or deep vein thrombosis. Few patients in the older age group are able to work after the diagnosis. Most of the patients are incapable of self-care for several months before death. The localized transfer of new genes into cancer cells potentially permits the expression of proteins with specific biologic functions that may provide a means to alter the biology of tumor growth through a variety of mechanisms including increasing tumor immunogenicity, inducing the local expression of toxic agents, and sensitization of tumors to chemotherapeutic agents. Gene therapy with the transfer of the drug susceptibility gene Herpes virus thymidine kinase (HSV-TK) has shown promise in a number of animal models, including CNS tumors. This study will evaluate the use of adenovirus-mediated transfer of the HSV-TK gene into primary human brain tumors followed by systemic treatment with ganciclovir. The goals of this phase I study are to evaluate the overall safety and efficacy of this treatment and to gain insight into the parameters that may limit the general applicability of this approach. In this phase I study, patients with recurrent gliomas will receive stereotactic-guided injections of the virus into the brain tumor, followed by intravenous ganciclovir for 14 days. Patients eligible to undergo a palliative debulking procedure will receive the same treatment followed by resection on day 7. At the time of resection a second dose of virus will be administered intra-operatively into the residual, unresectable portion of the tumor, and intravenous ganciclovir will be continued for additional 14 days. Tissue removed at the time of resection will be analyzed for evidence of adenovirus infection, thymidine kinase expression and signs of inflammation. The size and metabolic activity of all tumors will be followed by volumetric MRI scans and Position Emission Tomography Scans, respectively. Patients will be enrolled in groups of three, with each group receiving successively larger doses of adenovirus. This study will quantify the toxicity of this therapy, and provide evidence as to the duration of transgene expression and virus induced inflammation.

Adenoviridae Infections↗
PubMed1996

Gene therapy: socioeconomic and ethical issues. A roundtable discussion.

Gene therapy research has the potential to revolutionize the way in which many human diseases are treated. Despite its enormous potential, roundtable panelists concluded that the field needs time to mature scientifically without pressure to develop a marketable therapeutic product. In addition, health care decision makers, physicians, and the lay public need to be educated on the future medical, economic, and ethical ramifications of gene therapy.

Clinical Trials as Topic↗
PubMed1996

Hepatic expression of the catalytic subunit of the apolipoprotein B mRNA editing enzyme (apobec-1) ameliorates hypercholesterolemia in LDL receptor-deficient rabbits.

Apolipoprotein (apo) B48, a protein contained in intestinally derived lipoprotein particles, is synthesized by post-transcriptional editing of apoB100 mRNA. This reaction is mediated by an enzyme complex that includes the catalytic subunit, apobec-1. The liver of most mammals, by contrast, contains only unedited apoB mRNA and secretes apoB100, the major protein component of plasma low-density lipoprotein (LDL). Because rabbits, like humans, fail to edit hepatic apoB100 mRNA, we introduced a recombinant adenovirus encoding apobec-1 into the livers of LDL receptor-defective rabbits to determine the impact on lipoprotein metabolism of hepatic apoB48 secretion. Transgene expression was mainly confined to the liver and was sustained for up to 3 weeks following virus administration, as evidenced by the presence of apobec-1 mRNA and the ability of hepatic S100 extracts to edit a synthetic apoB RNA template in vitro. The transient induction of hepatic apoB mRNA editing accompanied alterations in very-low-density lipoprotein (VLDL) size, the presence of apoB48 in fractions spanning the VLDL and LDL range, and modest reductions in total plasma cholesterol levels.

APOBEC-1 Deaminase↗