Biomedical subjects

Malavosklish Bikram

Publications and source records attributed to Malavosklish Bikram.

5 recordsLinked to original sources

PubMed2005

Local, non-viral IL-12 gene therapy using a water soluble lipopolymer as carrier system combined with systemic paclitaxel for cancer treatment.

Development of improved gene transfer methods is needed for gene therapy to achieve its clinical potential. The use of biocompatible polymeric gene carriers has shown effectiveness in overcoming the current problems associated with viral vectors in safety, immunogenicity and mutagenesis. Previous work has demonstrated that repeated, local, non-viral interleukin-12 (IL-12) gene delivery successfully slows down tumor progression, while improving immunogenicity. Combining IL-12 gene delivery with systemic paclitaxel (PCT) chemotherapy as a treatment for various subcutaneous mouse mammary carcinomas, we used PCT with either a biodegradable polymeric solubilizer, HySolv or Cremophor EL for systemic treatment and injected water soluble lipopolymer (WSLP)/plasmid-encoding IL-12 gene (p2CMVmIL-12) complexes local once every week. The amount of lung metastases being essential for survival as well as subcutaneous tumor volume were compared against untreated controls. We showed inhibition of tumor growth and decreased lung metastases in the combined WSLP/p2CMVmIL-12/HySolv group compared to the controls and the PCT only treated groups. Compared to Cremophor, HySolv performed better alone or in combination with IL-12. Using polymeric vectors as gene carrier systems in combination with improved systemic therapies provide evidence for the efficacy and feasibility of polymer-based drug delivery systems. Especially local cytokine gene delivery showed augmentation of systemic chemotherapy while reducing the hosts risk for further systemic toxicity.

Animals↗

PubMed2004

Long-circulating DNA-complexed biodegradable multiblock copolymers for gene delivery: degradation profiles and evidence of dysopsonization.

Biodegradable cationic polymers have become promising alternatives to traditional polycationic gene delivery systems in which the high charge densities of high molecular weight polymers contribute significantly to cellular toxicities. Previous research has shown that biodegradable, multiblock copolymers (MBC), PEG-PLL-g-16% His, are efficient gene carriers with negligible cellular toxicities. The present research was designed to characterize the polymer degradation as well as to determine the biodistribution of the MBC after systemic administration. Polymer degradation was performed in buffer as a function of pH, in serum and within polymer/pDNA complexes. The MBC exhibited exponential decay with a half-life (t1/2) of approximately 14 min at pH 9.0, approximately 5 h at pH 7.4 and approximately 2 h in serum. However, there was little or no degradation observed at pH 4.0 and the MBC within the complexes degraded between 4 and 8 h in serum. Biodistribution data performed with fluorescently labeled polymer and pDNA revealed that intact complexes remained in the blood up to 3 days, which was also reflected in the organs as a function of time. Therefore, the cumulative data suggest that PEG may be sterically stabilizing complexes in vivo via dysopsonization in which serum proteins mask the complexes from elements of the reticuloendothelial system (RES).

Animals↗

PubMed2004

Combination of local, nonviral IL12 gene therapy and systemic paclitaxel treatment in a metastatic breast cancer model.

Repeated, local, nonviral IL12 (interleukin-12) gene delivery decreased tumor progression and increased immunogenicity. We combined our IL12 gene delivery with systemic paclitaxel chemotherapy as a treatment for paclitaxel (PCT)-resistant 4T1 subcutaneous mouse mammary carcinomas and PCT-sensitive, immunogenic/nonimmunogenic tumors. We mixed PCT with either a biodegradable polymeric solubilizer, HySolv, or Cremophor EL for bimonthly systemic treatments and injected water-soluble lipopolymer (WSLP)/p2CMVmIL-12 (plasmid encoding IL12 gene) complexes locally every week. We compared treated subcutaneous tumor volume and lung metastasis with controls. HySolv alone performed better compared to Cremophor EL in combination with WSLP/p2CMVmIL-12. We showed inhibition of 4T1 tumor growth and lung metastases in the combined WSLP/p2CMVmIL-12/HySolv group compared to the controls and the paclitaxel-only treated groups. In parallel experiments we also demonstrated additive responses for tumor growth and number of lung metastases within other PCT-sensitive mammary tumor models using this combination strategy. Our combination therapy provides evidence for the efficacy and feasibility of improved drug delivery systems. Local cytokine gene delivery can augment local and systemic chemotherapy without placing the host at risk for further systemic toxicity.

Animals↗

PubMed2004

Sp1-dependent regulation of the RTP801 promoter and its application to hypoxia-inducible VEGF plasmid for ischemic disease.

PURPOSE: Gene therapy using vascular endothelial growth factor (VEGF) is a new potential treatment of ischemic disease. To be safe and effective, VEGF expression should be enhanced locally in ischemic tissue. In this study, we identified the cis-regulatory element for the hypoxia induction of the RTP801 promoter. In addition, pRTP801-VEGF was evaluated as a therapeutic plasmid in vitro. METHODS: The cis-regulatory element for hypoxia induction was identified by deletion and mutation analyses. Antisense oligonucleotide co-transfection assay was performed to evaluate the role of Sp1. pRTP801-VEGF was constructed by the insertion of the RTP801 promoter into the VEGF plasmid. The hypoxia-inducible expression of VEGF was evaluated by in vitro transfection assay. RESULTS: In luciferase assay, the region between -495 and -446 was responsible for the hypoxia-induced transcription. The mutation of the Sp1 site in this region reduced hypoxia-induced transcription. In addition, co-transfection with antisense Sp1 oligonucleotide suggests that hypoxia induction of the RTP801 promoter is mediated by Sp1. In vitro transfection showed that pRTP801-VEGF had higher VEGF expression than pEpo-SV-VEGF. In addition, VEGF expression by pRTP801-VEGF was induced under hypoxia. CONCLUSIONS: With strong basal promoter activity and induction under hypoxia, pRTP801-VEGF may be useful for gene therapy for ischemic disease.

Cell Line↗

PubMed1999

Electron Spin Relaxation in Chromium-Nitrosyl Complexes.

A new method to prepare Cr(NO)(H(2)O)(5)(2+) from dichromate and NH(2)OH is reported. The chromium nitrosyls Cr(NO)(EHBA)(+) and Cr(NO)(EHBA)(2) (EHBA = 2-ethyl-2-hydoxybutyrate) were prepared by a literature reaction and characterized by continuous wave electron paramagnetic resonance and two-pulse electron spin echo spectroscopy at X-band. The g values are characteristic of a single unpaired electron in a predominantly d(xy)() orbital. In fluid and glassy solutions Cr(NO)(EHBA)(2) is a mixture of cis and trans isomers. Rotation of the methyl groups in the EHBA ligands causes an increased rate of spin echo dephasing at temperatures between 40 and 120 K. For the EHBA complexes echo envelope modulation is observed at temperatures below about 40 K that is attributed to inequivalent coupling to protons of the slowly rotating methyl groups. Both the effect of the methyl rotation on spin echo dephasing and the depth of the proton modulation are dependent on the number of ethyl groups in the ligand, and thus the spin echo experiments provide confirmation of the number of EHBA ligands in the complexes. The spin-lattice relaxation rates for the chromium-nitrosyl complexes at temperatures near 100 K are similar to values reported previously for Cr(V) complexes, which also have a single unpaired electron in a predominantly d(xy)() orbital. For Cr(NO)(H(2)O)(5)(2+), Cr(NO)(EHBA)(+), and Cr(NO)(EHBA)(2) the dominant contribution to spin-lattice relaxation between 12 and 150 K is the Raman process with a Debye temperature, theta(D), of 110-120 K. For Cr(NO)(CN)(5)(3)(-) the data are consistent with a Raman process (theta(D) = 135 K) and a contribution from a local mode, which dominates above about 60 K. The formally low-spin d(5) chromium nitrosyl complexes relax about 5 orders of magnitude more slowly than low-spin d(5) Fe(III) porphyrins, which is attributed to the absence of a low-lying excited state.

Journal Article↗