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Biomedical subjects

Richard Heller

Publications and source records attributed to Richard Heller.

At least 19 recordsLinked to original sources
PubMed2006

Complete regression of established subcutaneous B16 murine melanoma tumors after delivery of an HIV-1 Vpr-expressing plasmid by in vivo electroporation.

Novel therapies and delivery methods directed against malignancies such as melanoma, and particularly metastatic melanoma, are needed. The HIV-1 accessory protein Vpr (viral protein R) has previously been demonstrated to induce G2 cell cycle arrest as well as in vitro growth inhibition/killing of a number of tumor cells by apoptosis. In vivo electroporation has been utilized as an effective delivery method for pharmacologic agents and DNA plasmids that express "therapeutic" proteins and has been targeted to various tissues, including malignant tumors. For the study reported here, we hypothesized that intratumoral delivery of a Vpr expression plasmid through in vivo electroporation would induce apoptosis and growth attenuation or regression of melanoma tumors. Established subcutaneous B16.F10 melanoma tumors were injected intratumorally with a Vpr-expressing (either 25 or 100 microg) plasmid, followed by electroporation, on day 0 (i.e., when tumors had attained an appropriate size) and day 4. Treatment with 25 or 100 microg of the Vpr-expressing plasmid resulted in complete tumor regression with long-term survival in 14.3 and 7.1% of the mice, respectively. In addition, electroporative delivery of the Vpr-expressing plasmid was shown to induce apoptosis in tumors after intratumoral injection. This is the first report demonstrating the ability of Vpr, when delivered as a DNA expression plasmid with in vivo electroporation, to attenuate melanoma lesion growth and induce complete tumor regression coupled with long-term survival of mice in a highly aggressive and metastatic solid tumor model.

Animals↗
PubMed2006

Electric field mediated DNA motion model.

Understanding the motion and the governing equations of a molecule's path in tissue is an ultimate requirement for the repeatable, site specific delivery of molecules [Joseph D. Hickey. Modelling the Motion of Ions and Molecules in Electroporation and Electrophoresis Field Conditions. University of South Florida, College of Arts and Sciences, Department of Physics, Tampa, Florida, 2003., Joseph D. Hickey and Richard Gilbert. Modeling the electromobility of ions in a target tissue. DNA and Cell Biology, 22 (12) (2003) 823-828.]. This paper describes a computationally efficient mathematical model and simulation technique for the examination of DNA fragments in a 1% agarose gel. The speed of the individual DNA fragments through the agarose gel was described through two parts. The maximum velocity was calculated using the Coulombic force divided by Stoke's law and that value was retarded by an exponential rate equation. The simulation utilizes previously published techniques modified for this specific application [Joseph D. Hickey and Richard Gilbert. Fluid flow electrophoresis model. Bioelectrochemistry, 63 (2) (2004) 365-367., Joseph D. Hickey and Richard Gilbert. Modeling the electromobility of ions in a target tissue. DNA and Cell Biology, 22 (12) (2003) 823-828.]. Five representative DNA fragment sizes that span the resolution of a 1% agarose gel were chosen for this analysis. The speeds corresponding to these five DNA fragment sizes were converted into discrete values and used in a 50 step simulation. The resultant error comparing the simulation with experimental distance was 7.76%. Through a 1-D optimization procedure, this error was reduced to 3.02% for a 52 step simulation.

Algorithms↗
PubMed2006

Evaluation of toxicity following electrically mediated interleukin-12 gene delivery in a B16 mouse melanoma model.

PURPOSE: Interleukin-12 (IL-12) has potential as an immunotherapeutic agent for the treatment of cancer but is unfortunately associated with toxicity. Delivery of a plasmid encoding IL-12 with electroporation induces an antitumor effect in the B16 mouse melanoma model without serious side effects. To translate this observation to the clinic, an evaluation of toxicity was done in the mouse model. EXPERIMENTAL DESIGN: Weight change, tumor response, blood chemistry and hematology values, and serum IL-12 levels were evaluated. Multiple tissues were analyzed histopathologically. RESULTS: A pronounced reduction in tumor volume, including a large percentage of complete regressions, was observed after electrically mediated gene therapy. No significant increases in serum IL-12 levels were detected. Tumor-bearing mice showed an increased number of atypical hematology values when compared with normal naive controls. Statistically significant differences in chemistry and hematology values were observed sporadically in most of the standard chemistry and hematology categories in all groups. The only histopathologic abnormality specific to the animals receiving both plasmid and electroporation was inflammation associated with the kidney at the last time point. CONCLUSIONS: In general, mice that received both plasmid and electroporation showed the least abnormal histopathologic findings and were found to be in the best health, reflecting the reduced burden of disease. No significant toxic effects due to the IL-12 gene therapy were observed.

Animals↗
PubMed2006

Improving the implementation of evidence-based practice: a knowledge management perspective.

Experience of knowledge management initiatives in non-health care organizations can offer useful insights, and strategies, to implement evidence-based practice in health care. Knowledge management offers a structured process for the generation, storage, distribution and application of knowledge in organizations. This includes both tacit knowledge (personal experience) and explicit knowledge (evidence). Communities of practice are a key component of knowledge management and have been recognized to be essential for the implementation of change in organizations. It is within communities of practice that tacit knowledge is actively integrated with explicit knowledge. Organizational factors that limit the development of knowledge management, including communities of practice, in non-health care organizations need to be overcome if the potential is to be achieved within health care.

Diffusion of Innovation↗
PubMed2005

Electroporation for targeted gene transfer.

The utilisation of nonviral gene delivery methods has been increasing steadily, however, a drawback has been the relative low efficiency of gene transfer with naked DNA compared with viral delivery methods. In vivo electroporation, which has previously been used clinically to deliver chemotherapeutic agents, also enhances the delivery of plasmid DNA and has been used to deliver plasmids to several tissue types, particularly muscle and tumour. Recently, a large number of preclinical studies for a variety of therapeutic modalities have demonstrated the potential of electrically mediated gene transfer. Although clinical trials using gene transfer with in vivo electroporation have not as yet been realised, the tremendous growth of this technology suggests that the first trials will soon be initiated.

Animals↗
PubMed2003

Regulation of the innate and adaptive immune responses by Stat-3 signaling in tumor cells.

Although tumor progression involves processes such as tissue invasion that can activate inflammatory responses, the immune system largely ignores or tolerates disseminated cancers. The mechanisms that block initiation of immune responses during cancer development are poorly understood. We report here that constitutive activation of Stat-3, a common oncogenic signaling pathway, suppresses tumor expression of proinflammatory mediators. Blocking Stat-3 in tumor cells increases expression of proinflammatory cytokines and chemokines that activate innate immunity and dendritic cells, leading to tumor-specific T-cell responses. In addition, constitutive Stat-3 activity induces production of pleiotropic factors that inhibit dendritic cell functional maturation. Tumor-derived factors inhibit dendritic cell maturation through Stat-3 activation in progenitor cells. Thus, inhibition of antitumor immunity involves a cascade of Stat-3 activation propagating from tumor to dendritic cells. We propose that tumor Stat-3 activity can mediate immune evasion by blocking both the production and sensing of inflammatory signals by multiple components of the immune system.

Animals↗
PubMed2003

IL-12 gene therapy using an electrically mediated nonviral approach reduces metastatic growth of melanoma.

Interleukin-12 (IL-12) has been evaluated in both preclinical and clinical immunotherapy protocols as a potential therapy for melanoma. However, delivery of IL-12 in the form of recombinant protein can result in severe toxicity, and gene therapy has had limited success against B16.F10 murine melanoma. This study investigated the therapeutic effect of delivering a plasmid encoding IL-12 followed by electroporation on primary and secondary tumors. Three treatments of intratumoral (i.t.) plasmid injection and electroporation resulted in 80% of mice with B16.F10 melanoma tumors being tumor free for >100 days (cure). The "cured animals" were resistant to challenge with B16 cells. In a separate experiment, B16 cells were injected on the opposite flank of the treated tumor on the day of treatment. Eighty-seven percent of control mice developed a distant tumor while only 43.8% of mice receiving two or three i.t. electroporation treatments developed a distant tumor. For examination of tumor development in the lungs, mice were injected intravenously with B16.F10 cells then treated with i.m. injections of plasmid with or without electroporation. Only 37.5% of mice receiving i.m. injections and electroporation developed nodules in the lungs compared to 87.5% of mice in the no-treatment group. The results show that administration of a plasmid encoding IL-12 with electroporation has a therapeutic effect on primary tumors as well as distant tumors and metastases.

Angiogenesis Inhibitors↗
PubMed2002

Constitutive Stat3 activity up-regulates VEGF expression and tumor angiogenesis.

Non-receptor and receptor tyrosine kinases, such as Src and EGF receptor (EGFR), are major inducers of vascular endothelial growth factor (VEGF), one of the most potent mediators of angiogenesis. While tyrosine kinases signal through multiple pathways, signal transducer and activation of transcription 3 (Stat3) is a point of convergence for many of these and is constitutively activated with high frequency in a wide range of cancer cells. Here, we show that VEGF expression correlates with Stat3 activity in diverse human cancer cell lines. An activated Stat3 mutant (Stat3C) up-regulates VEGF expression and stimulates tumor angiogenesis. Stat3C-induced VEGF up-regulation is abrogated when a Stat3-binding site in the VEGF promoter is mutated. Furthermore, interrupting Stat3 signaling with dominant-negative Stat3 protein or Stat3 antisense oligonucleotide in tumor cells down-regulates VEGF expression. Consistent with an important role of Stat3 in VEGF up-regulation induced by various oncogenic tyrosine kinases, v-Src-mediated VEGF expression is inhibited when Stat3 signaling is blocked. Moreover, chromatin immunoprecipitation assays indicate that Stat3 protein binds to the VEGF promoter in vivo and mutation of a Stat3-binding site in the VEGF promoter abrogates v-Src-induced VEGF promoter activity. These studies provide evidence that the VEGF gene is regulated directly by Stat3 protein, and indicate that Stat3 represents a common molecular target for blocking angiogenesis induced by multiple signaling pathways in human cancers.

3T3 Cells↗
PubMed2002

IL-12 plasmid delivery by in vivo electroporation for the successful treatment of established subcutaneous B16.F10 melanoma.

Interleukin-12 (IL-12) has been used in numerous immunotherapy protocols against melanoma. However, delivery of IL-12 in the form of recombinant protein can result in severe toxicity, and gene therapy has had limited success against B16.F10 murine melanoma. The purpose of this study was to examine the effectiveness of in vivo electroporation for the delivery of plasmid DNA encoding IL-12 as an antitumor agent against B16.F10 melanoma. We treated mice bearing established B16.F10 melanoma tumors with intratumoral (i.t.) or intramuscular (i.m.) injections of a plasmid encoding IL-12, followed by in vivo electroporation. For i.t. treatments, we used an applicator containing six penetrating electrodes to deliver 1500-V/cm, 100-micros pulses. We administered i.m. pulses with an applicator containing four penetrating electrodes delivering 100-V/cm, 20-ms pulses. The i.t. treatment resulted in the cure of 47% of tumor-bearing mice, and 70% of cured mice were resistant to challenge with B16.F10 cells. The i.m. treatment did not result in tumor regression. We found that i.t. treatment resulted in increased levels of IL-12 and interferon-gamma (IFN-gamma) within the tumors, the influx of lymphocytes into the tumors, and reduction in vascularity. Neither i.m. nor i.t. treatment was successful against B16.F10 tumors in a nude mouse model, supporting a role for T cells in regression of this tumor model.

Angiogenesis Inhibitors↗
PubMed2002

Estimating the contribution of individual risk factors to disease in a person with more than one risk factor.

Various measures have been proposed to express the excess risk of an outcome attributable to one particular risk factor, such as attributable risk and risk fraction. However, there is sometimes a need, both in epidemiological studies and in awarding compensation in legal cases, to simultaneously consider the contribution of several risk factors to a disease outcome, when a biological model is not available. We propose a method that allocates the proportional contribution of several risk factors to a disease outcome, based on the weighted contribution of the risk fraction for each risk factor. We demonstrate the use of this method using figures for renal cell carcinoma, and discuss the caveats in using this method for epidemiologic studies, and in awarding compensation in legal cases.

Asbestos↗
PubMed2002

Combining quantitative and qualitative research to engage stakeholders in developing quality indicators in general practice.

In 2000, the Newcastle Institute of Public Health (NIPH) undertook a project that aimed to review, identify and where necessary, develop a range of indicators of quality service provision in general practice. We describe the way in which quantitative and qualitative research methods (including a Delphi style survey) were combined to investigate consensus amongst stakeholders in defining quality indicators. Over 500 general practice stakeholders were consulted. They included general practitioners (GPs) and their representative groups, academics, policy makers, and consumers. Several important lessons were learnt from the process, including the importance of involving a broad representative group of stakeholders, informing workshop participants in advance, providing adequate response times for the Delphi surveys and using videoconferencing technologies.

Aged↗
PubMed2002

Effect of electrically mediated intratumor and intramuscular delivery of a plasmid encoding IFN alpha on visible B16 mouse melanomas.

Interferon alpha may be used as a single agent therapy for metastatic malignant melanoma or as an adjuvant to chemotherapy. Delivery of interferon alpha by gene therapy offers an alternative to recombinant protein therapy. Electrically mediated delivery enhances plasmid expression in a number of tissues, for instance skin, liver, muscle and tumors including melanomas. Here we compare the effect of delivery of a plasmid encoding mouse interferon alpha on growth of visible B16 mouse melanomas following electrically mediated delivery to muscle or directly to the tumor. Intratumoral delivery of interferon alpha plasmid not only slows melanoma growth, but induces complete, long term, regression. This effect was not observed after intramuscular delivery.

Animals↗
PubMed2002

Overview of electroporation.

This special issue of Technology in Cancer Research and Treatment focuses on the versatility of electroporation. Contributed papers report on the basic mechanisms as well as the use of this procedure ex vivo and in vivo. In addition, recent studies utilizing in vivo electroporation for plasmid DNA and drug delivery are presented.

Animals↗
PubMed2002

Electric field enhanced plasmid delivery to liver hepatocellular carcinomas.

Electric field enhanced molecular delivery for cancer research and treatment is a new technology that has demonstrated its effectiveness in clinical trials using bleomycin or cisplatin (Heller, R., Gilbert, R., Jaroszeski, M. J. Clinical applications of electrochemotherapy, Advanced Drug Delivery Reviews 35,119-129, 1999), as chemotherapeutic agents. The technology is being investigated in research applications for applicability as a method to enhance gene expression in a target tumor. Success is predicated on an appropriate effective electric field mediated delivery protocol that triggers significant appropriate gene expression duration and levels. An electric field mediated delivery protocol includes a set of conditions associated with the electric field, the electroporation signature, as well as parameters associated with the plasmid and the electric field applicator. Manipulation of the electrical parameters within the electroporation signature generates different gene expression levels in liver hepatocellular carcinomas. Statistically significant gene expression levels were obtained that differed by an order of magnitude when two different electric field strength and duration conditions were employed.

Animals↗