Propofol hemisuccinate suppression of experimental autoimmune encephalomyelitis.

Propofol hemisuccinate is a prodrug water soluble form of the lipophilic, phenolic compound propofol (2,6-di-isopropylphenol), that is the active ingredient in the widely used anesthetic agent Diprovan. Propofol binds to GABA(A) receptors but also has a phenolic structure that confers antioxidant properties to the molecule. The effects of propofol hemisuccinate in rat experimental autoimmune encephalomyelitis (EAE) were studied using different doses and time regimes. Propofol hemisuccinate, 100 mg/kg given three times a day from day 7 or day 12 until day 16 after disease initiation, significantly reduced maximal EAE score. Histology studies supported the clinical findings demonstrating reduction in the inflammatory response in the lumbar spinal cord in animals treated with propofol hemisuccinate. Decreased levels of nitrotyrosine and unchanged levels of induced nitric oxide synthase suggest propofol hemisuccinate crossed the blood brain barrier and exerted its effects by lowering reactive oxygen species levels. The results suggest that propofol hemisuccinate may provide an alternative mode of treatment for acute exacerbations of multiple sclerosis.

Gene therapy strategies for the treatment of chronic viral hepatitis.

Chronic viral hepatitis is a major clinical problem, with over half a billion persons infected worldwide. Current therapies, principally treatment with recombinant IFN-alpha protein, have limited benefit. Recent studies suggest that gene-based expression of IFN-alpha is a possible therapeutic alternative that may improve the effectiveness of treatment. Gene delivery to the liver and consequent IFN-alpha expression therein, has the potential to concentrate the protein at the target organ and provide more continuous exposure to the therapeutic agent. Other potential gene and nucleic acid therapeutics for viral hepatitis are also being investigated. Key to the deployment of these future therapies is a suitable method of gene delivery. Although recombinant viral vector systems, such as adenovirus, are currently the most effective means of gene delivery to the liver, their use presents many concerns. These include immune and inflammatory reactions to the viral vector and possible adverse interactions between the recombinant virus and the pre-existing viral infection. Non-viral gene delivery systems would be a preferred treatment modality. The efficiency of current non-viral systems is not adequate for systemically administered liver gene therapy. However, recent use of membrane permeabilisation techniques has shown that high efficiency non-viral gene transfer agents are possible. The future coupling of these improved delivery systems with gene- or nucleic acid-based therapeutics currently in development holds out great promise for new generations of antihepatitis therapies.

Strength of conjugate binding to plasmid DNA affects degradation rate and expression level in vivo.

In vitro assays have demonstrated the capability of poly-L-lysine to protect plasmid DNA from serum nucleases and cellular lysates. Our purpose was to evaluate the stability and potency of poly-L-lysine-DNA polyplexes after intravenous injection into mice. Polyplexes consisted of 32P-radiolabeled plasmid DNA complexed with poly-L-lysine at specified charge ratios. Variations in conjugate hydrophobicity and levels of modification with polyethylene glycol were investigated. Our results show that, in contrast to in vitro studies, the systemically administered polyplexes exhibited marked DNA degradation in the vascular compartment within 5 min. Substitution of poly-L-lysine epsilon-amino sites with polyethylene glycol or hydrocarbon chains resulted in faster degradation even when complexed at higher charge (+/-) ratios. Use of excess cationic charge in the polyplexes (+/- 2.5) diminished degradation rates only slightly. An analysis was made of the strength of the poly-L-lysine:DNA interaction by competition with poly-aspartic acid. Polyplexes with the strongest binding between conjugate and DNA in the competition assay were also the most stable in blood. However, tighter binding was not enough to fully protect the polyplex in vivo and polyplex DNA was substantially degraded within 10 min. Increased polyplex stability did not correlate with improved in vivo transfection efficiency.

Obstacles and advances in non-viral gene delivery.

This review focuses on recent progress and novel strategies to improve the efficiency of in vivo non-viral gene delivery. Examples of the most promising attempts to overcome specific barriers are presented in fuller detail. Current research into several of the most difficult steps in the gene delivery pathway is discussed including particle stabilization, targeting, cytoplasmic entry and access to the nucleus. The impact of recent reports on our current understanding of the true limitations to in vivo delivery is also discussed. The importance of preclinical animal models for the development of clinical applications of gene therapy is noted.

HIV prevalence at reception into Australian prisons, 1991-1997.

OBJECTIVE: To measure the extent and outcome of HIV antibody testing at reception into Australian prisons. DESIGN: Cross-sectional survey at reception into prison. PARTICIPANTS AND SETTING: People received into Australian prisons from 1991 to 1997. MAIN OUTCOME MEASURES: Number of people tested for HIV infection and prevalence of diagnosed HIV infection. RESULTS: In 1991-1997, HIV antibody testing was carried out for 72% of prison entrants in Australia; the percentage tested declined significantly from 76% in 1991 to 67% in 1997 (P < 0.001). In New South Wales, the percentage of entrants tested at reception into prison dropped from almost 100% in 1991-1994 to 45% in 1997, whereas in the Northern Territory, South Australia and Western Australia the extent of testing increased significantly (P < 0.001). HIV prevalence was 0.2% among people received into Australian prisons in 1991-1997, and did not differ by sex. Most people with HIV infection (242/378; 64%) received into prison in 1991-1997 had been diagnosed at a previous entry; 136 people (36% of the total number of diagnoses) were newly diagnosed at reception into prison. CONCLUSIONS: A national monitoring system in place from 1991 indicates generally high rates of HIV antibody testing and a low prevalence of HIV infection among people entering Australian prisons. In each year, people not previously known to the prison health service to have HIV infection were received into prison, indicating continuing HIV infection in the population entering Australian prisons.

Stabilization of poly-L-lysine/DNA polyplexes for in vivo gene delivery to the liver.

We are developing a self-assembling non-viral in vivo gene delivery vehicle based on poly-l-lysine and plasmid DNA. We have characterized poly-l-lysines of different chain lengths for DNA condensation and strength of DNA binding. Poly-l-lysine chains >20 residues bound DNA efficiently in physiological saline, while shorter chains did not. Attachment of asialoorosomucoid to PLL increased the PLL chain length required for efficient DNA binding in saline and for efficient DNA condensation. By electron microscopy, poly-l-lysine/DNA polyplexes appeared as toroids 25-50 nm in diameter or rods 40-80 nm long; conjugation of asialoorosomucoid to the polylysine component increased the size of resulting polyplexes to 50-90 nm. In water, poly-l-lysine and asialoorosomucoid-PLL polyplexes have effective diameters of 46 and 87.6 nm, respectively. Polyplexes containing only poly-l-lysine and DNA aggregated in physiological saline at all charge ratios and aggregated at neutral charge ratios in water. Attachment of asialoorosomucoid lessened, but did not eliminate, the aggregation of PLL polyplexes, and did not result in efficient delivery of polyplexes to hepatocytes. Conjugation of polyethylene glycol to poly-l-lysine sterically stabilized resulting polyplexes at neutral charge ratios by shielding the surfaces. For efficient in vivo gene delivery, polyplexes will need to be sterically stabilized to prevent aggregation and interaction with serum components.