Functional characterisation of novel analgesic product based on self-regulating drug carriers.

We compared a new formulation of ketoprofen (Diractin) based on ultradeformable vesicle (Transfersome) carriers with conventional topical gels with the drug (Gabrilen; Togal Mobil Gel; Fastum). Depending on water concentration, between a few percent and >95% of ketoprofen in Diractin is associated with the vesicles. The low free drug concentration on open skin (1-3%) minimises ketoprofen diffusion from Diractin through the organ, keeping effective permeability coefficient for the product (even after increase to approximately 3.5 x 10(-3) cm h(-1) at 24h) below that of conventional gels ( approximately 0.3-2.1 x 10(-1) cm h(-1)). The carrier's stress-responsiveness enables constriction crossing without vesicle breakdown. The carrier stiffening upon dilution, e.g. in tissues below the skin's diffusive barrier, helps avoiding the drug uptake in cutaneous blood capillaries. Diractin therefore can deposit ketoprofen in deep subcutaneous tissues, which the drug from conventional gels reaches mainly via systemic circulation. In vitro efficacy of daily drug delivery through skin is < or =1.6% for conventional topical NSAID gels and merely approximately 0.05% for Diractin. In contrast, in vivo ketoprofen transport by ultradeformable carriers through non-occluded skin into living pigs' subcutaneous muscles is 5-14x better than for conventional gels. Locally targeted drug transport by the self-regulating, ultradeformable vesicles is thus clearly non-diffusive and quite efficient.

Abundant defective viral particles budding from microglia in the course of retroviral spongiform encephalopathy.

A pathogenetic hallmark of retroviral neurodegeneration is the affinity of neurovirulent retroviruses for microglia cells, while degenerating neurons are excluded from retroviral infections. Microglia isolated ex vivo from rats peripherally infected with a neurovirulent retrovirus released abundant mature type C virions; however, infectivity associated with microglia was very low. In microglia, viral transcription was unaffected but envelope proteins were insufficiently cleaved into mature viral proteins and were not detected on the microglia cell surface. These microglia-specific defects in envelope protein translocation and processing not only may have prevented formation of infectious virus particles but also may have caused further cellular defects in microglia with the consequence of indirect neuronal damage. It is conceivable that similar events play a role in neuro-AIDS.

Suppression of rat bone marrow cells by Friend murine leukemia virus envelope proteins.

In a retroviral rat model, we have investigated the nontransforming effects of murine leukemia virus FB29 on the bone marrow. Upon intraperitoneal inoculation with murine leukemia virus FB29 of either neonatal or adult rats, bone marrow cells became massively infected within the first 12 days postinoculation. In neonatally inoculated rats, a persistent productive bone marrow infection was established, whereas in rats inoculated as adults, no infected bone marrow cells could be detected beyond 12 days postinoculation. Retroviral infection was most likely cleared by an antiviral immune response (Hein et al., 1995, Virology 211, 408-417). Exposure to virus irreversibly decreased numbers of bone marrow cells staining with monoclonal antibody OX7 by 10-30%. Reduction of OX7+ bone marrow cells by 20% was also observed in vitro, after bone marrow cells from uninfected adult rats had been co-incubated with virus. FB29-envelope proteins were sufficient alone to reduce numbers of OX7+ bone marrow cells, both in vivo and in vitro. According to results on incorporation of propidium iodide, decreased numbers of OX7+ cells were due to cell death. By flow cytometric analyses OX7+ bone marrow cells as well as monocytes/macrophages were identified to be major target cells for infection with FB29 within the bone marrow. Thus, the mechanism(s) responsible for death of OX7+ bone marrow cells might be due to direct toxicity of viral envelope proteins and/or to interactions of viral envelope proteins with cells of the monocytic lineage.

Murine leukemia virus-induced neurodegeneration of rats: enhancement of neuropathogenicity correlates with enhanced viral tropism for macrophages, microglia, and brain vascular cells.

A highly neuropathogenic retrovirus, NT40, was generated by serially passaging an infectious molecular clone of Friend murine leukemia virus, FB29, through F344 Fisher rats. NT40 induced severe neurological signs such as reflex abnormalities and ataxia within 4-6 weeks following neonatal inoculation. FB29 led to only very mild neurological dysfunctions with longer incubation periods. Pathological alterations were characterized by mild (FB29) to extensive (NT40) noninflammatory spongiform degeneration, mainly of brain-stem areas. Infectious center assays revealed that viral titers in brain tissues of NT40-infected rats were 100-fold higher than those of FB29-infected animals. Employing immunohistochemistry, in situ hybridization, and flow cytometry, NT40 was found to infect many endothelial cells of brain blood vessels and microglia, whereas FB29 infected only microglia and those to a lower extent. However, when isolated from adult diseased rats, microglial cells turned out in both cases to be nonproductively infected with either FB29 or NT40. Of peripheral organs, we found enhanced levels of NT40 in peritoneal macrophages but not in spleen, thymus, or serum when compared to FB29. Altogether these data suggest that an expanded cellular tropism within the CNS and elevated viral titers in macrophages and microglia correlated with enhancement of neuropathogenicity.