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Ever since the publication of the first reports in 1990 using skeletal muscle as a direct target for expressing foreign transgenes, an avalanche of papers has identified a variety of proteins that can be synthesized and correctly processed by skeletal muscle. The impetus to the development of such applications is not only amelioration of muscle diseases, but also a range of therapeutic applications, from immunization to delivery of therapeutic proteins, such as clotting factors and hormones. Although the most efficient way of introducing transgenes into muscle fibres has been by a variety of recombinant viral vectors, there are potential benefits in the use of non-viral vectors. In this review we assess the recent advances in construction and delivery of naked plasmid DNA to skeletal muscle and highlight the options available for further improvements to raise efficiency to therapeutic levels.Gene Therapy (2003) 10, 131–142. doi:10.1038/sj.gt.3301874 [ABSTRACT FROM AUTHOR]

Muscle can be used for systemic delivery of non-muscle proteins. In order to investigate the relative effectiveness of direct DNA plasmid injection versus implantation of genetically modified myogenic cell lines, we have used the human alpha 1 anti-trypsin (α1AT) cDNA driven by either cytomegalovirus (CMV) or the muscle creatine kinase 3.3 kb (MCK) promoter in immunodeficient mice. We dem- onstrate that the implantation of transfected myoblasts stably expressing the human α1AT cDNA generates a more persistent production of α1AT than does direct intramuscular injection of the same construct as plasmid DNA. Moreover, immunohistological labelling of muscle sections implanted with myoblasts show that the newly formed muscle fibres are those containing the human protein. [ABSTRACT FROM AUTHOR]

The intracellular distribution of lysosomal enzymes in lymphocytes has previously been only poorly defined, mainly by cytochemical procedures of low resolution. In the present study we have used a post-embedding immunogold technique to identify the precise ultrastructural localization of a lysosomal enzyme, β-glucuronidase, in activated lymphocytes embedded in Lowicryl K4M resin. We show that this enzyme is present in the rough endoplasmic reticulum, in the Golgi complex, and in vesicular organelles which probably include lysosomes. [ABSTRACT FROM AUTHOR]

The original publication of this article contained an incorrect version that did not include some final reviewers' suggestions, was inadvertently received for production and published. The original article has been corrected. [ABSTRACT FROM AUTHOR]

Objective: Nitisinone induced hypertyrosinaemia is a concern in patients with Alkaptonuria (AKU). It has been suggested that this may alter neurotransmitter metabolism, specifically dopamine and serotonin. Herein mass spectrometry imaging (MSI) is used for the direct measurement of 2,4-diphenyl-pyranylium tetrafluoroborate (DPP-TFB) derivatives of monoamine neurotransmitters in brain tissue from a murine model of AKU following treatment with nitisinone. Methods: Metabolite changes were assessed using MSI on DPP-TFB derivatised fresh frozen tissue sections directing analysis towards primary amine neurotransmitters. Matched tail bleed plasma samples were analysed using LC–MS/MS. Eighteen BALB/c mice were included in this study: HGD−/− (n = 6, treated with nitisinone—4 mg/L, in drinking water); HGD−/− (n = 6, no treatment) and HGD+/− (n = 6, no treatment). Results: Ion intensity and distribution of DPP-TFB derivatives in brain tissue for dopamine, 3-methoxytyramine, noradrenaline, tryptophan, serotonin, and glutamate were not significantly different following treatment with nitisinone in HGD −/− mice, and no significant differences were observed between HGD−/− and HGD+/− mice that received no treatment. Tyrosine (10-fold in both comparisons, p = 0.003; [BALB/c HGD−/− (n = 6) and BALB/c HGD+/− (n = 6) (no treatment) vs. BALB/c HGD−/− (n = 6, treated)] and tyramine (25-fold, p = 0.02; 32-fold, p = 0.02) increased significantly following treatment with nitisinone. Plasma tyrosine and homogentisic acid increased (ninefold, p = < 0.0001) and decreased (ninefold, p = 0.004), respectively in HGD−/− mice treated with nitisinone. Conclusions: Monoamine neurotransmitters in brain tissue from a murine model of AKU did not change following treatment with nitisinone. These findings have significant implications for patients with AKU as they suggest monoamine neurotransmitters are not altered following treatment with nitisinone. [ABSTRACT FROM AUTHOR]