David N. Weissman

Fulminant Hepatitis During Herpes Simplex Virus Infection in Apparently Immunocompetent Adults: Report of Two Cases and Review of the Literature

Two apparently immunocompetent adult patients developed acute fulminant hepatitis during presumptive primary herpes simplex virus type 1 (HSV-1) infection without any visible mucocutaneous lesions. HSV hepatitis was not suspected in the case of patient 1, who died without treatment. Patient 2 was empirically treated with acyclovir because of the triad of high fever, leukopenia, and markedly elevated levels of aminotransferases, and this patient survived. Most immunocompetent patients with fulminant HSV hepatitis do not have visible mucocutaneous ulcers, and HSV is frequently not considered as a cause of acute hepatitis. In summary, fulminant hepatitis can occur during HSV infections, the diagnosis is frequently missed or delayed because of the absence of mucocutaneous ulcerations, and patients who receive early empirical treatment with acyclovir can survive this illness.

Antisense Inhibition of Silica-induced Tumor Necrosis Factor in Alveolar Macrophages

Tumor necrosis factor-α (TNFα) has been shown to play an important role in the pathogenesis of silicotic fibrosis. In this study, antisense oligonucleotides targeted to TNFα mRNA were used to inhibit silica-induced TNFα gene expression in alveolar macrophages. To achieve macrophage-specific oligonucleotide delivery, a molecular conjugate consisting of mannosylated polylysine that exploits endocytosis via the macrophage mannose receptor was used. Complexes were formed between the mannosylated polylysine and oligonucleotides and added to the cells in the presence of silica. Enzyme-linked immunoadsorbent assay showed that the complex consisting of the conjugate and antisense oligomer effectively inhibited TNFα production, whereas the oligomer alone had much less effect. Reverse transcriptase-polymerase chain reaction analysis revealed that the reduction in TNFα secretion was associated with specific ablation of targeted TNFα mRNA. The conjugate alone or conjugate complexed with inverted or sense sequence oligonucleotide had no effect. The promoting effect of the conjugate on antisense activity was shown to be due to enhanced cellular uptake of the oligomer via mannose receptor-mediated endocytosis. Cells lacking mannose receptors showed no susceptibility to the conjugate treatment. These results indicate that effective and selective inhibition of macrophage TNFα expression can be achieved using the antisense mannosylated polylysine system.

A Cell-Based Drug Delivery System for Lung Targeting: II. Therapeutic Activities on B16-F10 Melanoma in Mouse Lungs

The in vitro and in vivo anticancer activities of doxorubicin-loaded B16-F10 murine melanoma cells (DLTC) were evaluated. DLTC showed similar growth-inhibitory effects against live B16-F10 cells with doxorubicin solution in cell culture system, with the IC50The in vitro and in vivo anticancer activities of doxorubicin-loaded B16-F10 murine melanoma cells (DLTC) were evaluated. DLTC showed similar growth-inhibitory effects against live B16-F10 cells with doxorubicin solution in cell culture system, with the IC50 of 0.11 microM and 0.17 microM, respectively. However, DLTC demonstrated higher effectiveness than the free solution in treating mouse lung cancer caused by live B16-F10 cells. Syngeneic C57BL mice were inoculated intravenously with live B16-F10 cells first, and then received daily treatment of intravenous injections of doxorubicin in either DLTC or free solution form. Compared with the control group treated with phosphate-buffered saline, DLTC eradicated almost all the lung cancer colonies (>99%), while the free solution form reduced the colonies by 61%, when the treatment was given at an early stage. If the treatment started after the establishment of micrometastatic colonies in the mouse lungs, DLTC and free solution treatment resulted in 85% and 30% cancer reduction, respectively. Additional experiments demonstrated that the reduction of lung cancer colonies by DLTC was related to the initial treatment time: the earlier the treatment, the greater the effect. In conclusion, DLTC showed better therapeutic outcomes than free solution form in treating lung cancer of our animal model.

Meeting Report: Mode(s) of Action of Asbestos and Related Mineral Fibers

Background: Although asbestos in general is well known to cause a range of neoplastic and non-neoplastic human health effects, not all asbestos fiber types have the same disease-causing potential, and the mode of action (MOA) of specific types of asbestos and related fibers for various health outcomes are not well understood. Objectives: A workshop was held to discuss the state of the science of the MOA for asbestos-related disease. The objective was to review the range of asbestos-induced health effects (including those at sites remote to the respiratory tract). We sought to identify existing knowledge gaps and define what research is needed to address these gaps and advance asbestos research. Discussion: Discussions centered on areas of uncertainty in the field, including the ways asbestos is defined and characterized, the role of different fiber characteristics (e.g., length and mineralogy) in disease, and the impact of low-dose exposures on human health. Studying the dosimetry and mode of action of multiple fiber types would enhance our understanding of asbestos-related disease. To better elucidate the MOA of specific asbestos fibers, the risk assessor requires data as to specific characteristics of asbestos in determining fiber toxicity (e.g., surface area, mineral type), which may inform efforts to assess and control exposures and prevent adverse human health outcomes for the diverse range of fiber types. Specific research aims were defined for these topics and for overarching issues to be addressed, including the use of standardized terminology, test materials, and better experimental models to aid in data extrapolation to humans. Conclusion: To resolve these and other issues, participants agreed that diverse scientific disciplines must coordinate to better understand the MOA leading to the various asbestos-related disease end points.

A cell-based drug delivery system for lung targeting: I. Preparation and pharmacokinetics.

A drug-loaded tumor cell (DLTC) system has been developed for lung metastasis-targeting drug delivery. Doxorubicin was loaded into B16-F10 murine melanoma cells (96 microg/10(6) cells). The loading process led to the death of all the carrier cells. The diameter of DLTC was 15.03+/-2.36 microm (mean +/- SD). The amount and rate of doxorubicin being released from the DLTC mainly depended on the drug loading and carrier cell concentration. Over a 6-month storage in phosphate buffered saline (PBS) at 4 degrees C, the decrease in intracellular drug concentration and the carrier cell number were less than 25% and 5%, respectively. After a bolus injection of 30 microg doxorubicin in either DLTC form or free solution into the mice tail veins, drug deposit in the lung from DLTC was 3.6-fold of that achieved by free drug solution. The latter resulted in higher drug content in liver and spleen. Extensive trypsinization of DLTC reduced its lung targeting effect by 30%, and the density of surface adhesion molecule GM3 on DLTC surface by 25%. In conclusion, this DLTC system demonstrated a lung-targeting activity that may be partially attributed to its specific surface characteristics.A drug-loaded tumor cell (DLTC) system has been developed for lung metastasis–targeting drug delivery. Doxorubicin was loaded into B16-F10 murine melanoma cells (96 1g/106 cells). The loading process led to the death of all the carrier cells. The diameter of DLTC was 15.03 § 2.36 1m (mean § SD). The amount and rate of doxorubicin being released from the DLTC mainly depended on the drug loading and carrier cell concentration. Over a 6-month storage in phosphate buffered saline (PBS) at 4±C, the decrease in intracellular drug concentration and the carrier cell number were less than 25% and 5%, respectively. After a bolus injection of 30 1g doxorubicin in either DLTC form or free solution into the mice tail veins, drug deposit in the lung from DLTC was 3.6-fold of that achieved by free drug solution. The latter resulted in higher drug content in liver and spleen. Extensive trypsinization of DLTC reduced its lung targeting effect by 30%, and the density of surface adhesion molecule GM3 on DLTC surface by 25%. In conclusion, this DLTC system demonstrated a lung-targeting activity that may be partially attributed to its specix8e c surface characteristics.

Immune Dysfunction in Silicosis: A Hypothesis

Abstract Silicosis is a fibrosing lung disease induced by silica particle inhalation. In addition to its effects on pulmonary physiology, the disease is also associated with clinically important immune dysfunction, detectable both systemically and in the lung. An important local pulmonary manifestation of silicosis-associated immune dysfunction is impaired host defense against mycobacteria. Normal host defense against mycobacteria is accomplished through cell-mediated responses by T cells and macrophages. The mechanism underlying impaired antimycobacterial defense and silicotuberculosis in silicotics is unknown. Despite impaired host defense against mycobacteria, silicosis appears to be associated with increased and dysregulated antibody production, as evidenced by the presence of hypergammaglobulinemia, circulating immune complexes, and autoantibodies in many patients with silicosis. The apparent paradox of excess antibody production, but impaired cell-mediated immunity, is not unique to silicosis. In a ...