Current Drug Targets - Volume 3, Issue 1, 2002

Artificial self-assembling systems are currently widely investigated as an alternative approach to recombinant viruses for gene transfection in vitro and in vivo. Cationic lipids are particularly attractive, as a great variety of well-characterized reagents can be synthesized from there. Over the last few years, numerous cationic lipid systems have been developed and shown to be efficient for in vitro transfection. However, although some promising results have been reported in the in vivo setting (even in clinical gene therapy trials in man), the in vivo use of cationic lipid-based systems is still problematic, especially when considering the systemic route of administration. Herein, we summarize our own research on a particular class of cationic lipids, cholesterol derivatives characterized by polar headgroups with guanidinium functions, in order to illustrate the basic principles of and the positive results already obtained by cationic lipid-mediated gene delivery as well as the remaining problems that need to be urgently resolved, particularly as regards the systemic administration. In this forward-looking review, we also discuss the present efforts to develop modular systems for improved in vivo transfection. Indeed, lipid-based vectors offer the possibility to create sophisticated modular gene delivery systems capable of self-assembly via hydrophobic interaction between their components, the role of the different functional elements being to help in overcoming the distinct extracellular and cellular barriers to in vivo gene transfection into the various somatic target tissues.

The number of individuals infected with human immunodeficiency virus (HIV) and other pathogens causing sexually transmitted diseases (STDs) is growing dramatically worldwide. Globally, heterosexual transmission may account for as much as 85-90% of new cases of HIV infection. Latex condoms represent an effective barrier against sexually transmitted pathogens, but unfortunately, their use is not generalized. Therefore, there is an urgent need to develop safe and potent topical microbicides under the control of women to efficiently reduce the spread of sexually transmitted infections. Sodium lauryl sulfate (SLS), an anionic surfactant with protein denaturing potency, is a potent inhibitor of the infectivity of several enveloped (Herpes simplex viruses, HIV-1, Semliki Forest virus) and nonenveloped (papillomaviruses, reovirus, rotavirus and poliovirus) viruses. The mechanism of action of SLS involves the solubilization of the viral envelope and / or the denaturation of envelope and / or capsid proteins. Studies have shown that SLS is not toxic for cultured cell lines of different origins at concentrations that inactivate HIV-1, herpes and human papillomavirus in vitro. In addition, intravaginal pretreatment of mice with a gel formulation containing SLS, completely protected animals against Herpes simplex virus type-2 infection. The gel formulation containing SLS was also well-tolerated following repeated intravaginal administrations to rabbits. Taken together, these data suggest that SLS represents a potential candidate for the use as a topical microbicide to prevent the sexual transmission of HIV-1, herpes, human papillomavirus and possibly other sexually transmitted pathogens. The impact of such a preventive tool on public health can be enormous.

Generally speaking, we cannot fully understand the mechanisms of general anesthesia until the molecular mechanisms of consciousness are fully elucidated. Loss of consciousness induced by general anesthetics might involve sensation, motor activity, behavior, memory and self-consciousness. The effects of many anesthetics are not limited to humans but also extend to the animals. Similar levels of minimum anesthetic concentrations are required to induce anesthesia in animals and human, i.e., the minimum alveolar concentration (MAC). Such similarity probably reflects identical anesthetic target molecules and functional conservation based on gene conservation. Thus, to study the mechanisms of anesthetic action, various animal models that are accessible to genetic manipulation, such as nematodes (Caenorhabditis elegans), fruit flies (Drosophila) and mice can be used. Genetic techniques allow for the rapid identification and characterization of genes involved in the actions of general anesthetics. In this review, I will describe the genetic mutations and putative target genes of general anesthetics.

Chronic musculo-tendinous pain syndromes are relatively common and associated with very high socio-economic costs. Their aetiology and pathogenesis are still unknown. In the athletic population, chronic tendon pain is most often seen among recreational male and female athletes in the age group between 30-60 years, and is considered to be associated with overuse of the aged tendon. Treatment is known to be difficult. In general, these chronic painful conditions have been considered to include an inflammatory component, and the nomenclature used (tendinitis, tendonitis) most often implies an inflammatory involvement. Despite that tendon biopsies have shown an absence of inflammatory cell infiltration, anti-inflammatory agents (NSAID'S, corticosteroidal injections) are most often included in the treatment. Our research has been focused on chronic painful conditions in the Achilles-, patellar-, and extensor carpi radialis brevis (ECRB)-tendons. We have demonstrated, for the first time, that it is possible to use the microdialysis technique for in vivo investigations of human tendons, and that the excitatory neurotransmitter glutamate exists in human tendons. We have identified and measured the concentrations of prostaglandin E2 (PGE2) in tendons as well. The results showed that chronic painful tendinosis (Achilles-, patellar-, ECRB-) had significantly higher concentrations of glutamate, but not PGE2, as compared to the pain-free normal tendons. With the use of immunohistochemical analyses and enzyme histochemistry of human Achilles- and patellar tendon biopsies, we have also, for the first time demonstrated that glutamate NMDAR1-immunoreaction was present in nerve structures. These findings altogether, indicate that glutamate might be involved in chronic tendon pain, and further emphasizes that there is no chemical inflammation (normal PGE2 levels) in the chronic stage of these relatively common so-called tendinopathies. The findings of glutamate and it's NMDAR1-receptors might have implications for treatment and be a potential target for drugs.

Hypericin, a naturally occurring pigment, is found in certain species of plants from the genus Hypericum, the most common of which is Saint John's Wort (Hypericum perforatum). Recent interest in hypericin is provoked by the discovery that it possesses extremely high toxicity towards certain viruses notably the class of enveloped viruses that includes human immunodeficiency virus (HIV) and toward tumors, and that this toxicity absolutely requires light. Consequently, a detailed understanding of the interaction of hypericin with cellular components (membranes, proteins, nucleic acids) and with light is of fundamental biological importance. The antiviral and antineoplastic activities of hypericin and its derivatives and its mode of action have been widely studied, in the last two decades. This review is focused on the results obtained in the study of hypericin heteroassociations with biological macromolecules, DNA and human serum albumin in particular. An alternative type of the hypericin photosensitizing activity associated with its ability to produce a photogenerated pH drop is discussed that and discussed in connection with its potential application in photodynamic therapy. In the review, it is also presented how an interdisciplinary approach supported by sophisticated techniques of optical spectroscopy and molecular modeling can be effectively applied for the identification of the specific binding sites of the drug in some biomacromolecules as well as for the determination of the physico-chemical mechanism of the biological activity of hypericin.

The secosteroid hormone 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) is a key player in the regulation of bone mineralization and calcium homeostasis. In addition, 1,25-(OH)2D3 has antiproliferative and prodifferentiation effects on various cells in vitro and in vivo. The growth-inhibitory properties of 1,25-(OH)2D3 could be harnessed in the treatment of cancer. However, its use as an anti-cancer drug is limited because of the calcemic effects of pharmacological doses. In an attempt to dissociate the antiproliferative and calcemic effects, numerous vitamin D3 analogs were developed. The mechanisms by which 1,25-(OH)2D3 and 1,25-(OH)2D3 analogs exert their growth-inhibitory effects are not clear but include effects on cell differentiation, apoptosis, cell cycle regulation, metastases, and angiogenesis. In the current review aspects involved in the tumor suppressive activity of 1,25-(OH)2D3 and 1,25-(OH)2D3 analogs will be addressed. The use of vitamin D3 compounds, alone or in combination with other drugs, in cancer treatment and the potential drawbacks will also be discussed.