Exposure of SV40-transformed Chinese hamster embryo cells (line CO50) to a series of physical and chemical carcinogens (including activation-dependent and activation-independent varieties) resulted in the induction of viral DNA synthesis. The carcinogen mediated amplification of SV40 DNA was demonstrated by a highly sensitive in situ hybridization procedure for the detection of cells synthesizing SV40 DNA. Treatment of CO50 cells with an inhibitor of polycyclic hydrocarbon metabolism (7,8-benzoflavone) prior to the application of benzo[a]pyrene or 7,12-dimethylbenz[a]anthracene prevented the induction of SV40 DNA synthesis, indicating that the induction depends upon the metabolic activation of these compounds. Non-carcinogenic hydrocarbons were inactive under this assay. Two different protocols for determining the inducing potential of a compound are presented. The properties of this test and its possible use as a short-term assay for potential carcinogens is discussed. The possibility that the induction of SV40 DNA synthesis is a reflection of a general gene amplification phenomenon mediated by carcinogens is discussed.

We have investigated different parameters characterizing carcinogen-mediated enhancement of methotrexate resistance in Chinese hamster ovary (CHO) cells and in simian virus 40-transformed Chinese hamster embryo (C060) cells. We show that this enhancement reflects dihydrofolate reductase (dhfr) gene amplification. The carcinogens used in this work are alkylating agents and UV irradiation. Both types of carcinogens induce a transient enhancement of methotrexate resistance which increases gradually from the time of treatment to 72 to 96 h later and decreases thereafter. Increasing doses of carcinogens decrease cell survival and increase the enhancement of methotrexate resistance. Enhancement was observed when cells were treated at different stages in the cell cycle, and it was maximal when cells were treated during the early S phase. These studies of carcinogen-mediated dhfr gene amplification coupled with our earlier studies on viral DNA amplification in simian virus 40-transformed cells demonstrate that the same parameters characterize the amplification of both genes. Possible cellular mechanisms responsible for the carcinogen-mediated gene amplification phenomenon are discussed.Although environmental agents have been shown to play an important role in the initiation of most human cancers, little is known about the molecular mechanisms underlying their action. Tumorigenesis is accompanied by a variety of molecular processes including DNA rearrangements (18, 21), oncogene activation (2) and amplification (5,24,25), and the appearance of double-minute chromosomes and homogeneously staining regions containing amplified DNA sequences (7,10,16).In recent years we studied the effect of chemical and physical carcinogens on one of these cancer-related phenomena, namely, gene amplification, in an attempt to establish its possible role in the initiation events of carcinogenesis. To study gene amplification immediately after exposure to the carcinogens rather than after the long process of establishing cell lines containing amplified genes, we have constructed an experimental model system consisting of simian virus 40 (SV40)-transformed Chinese hamster cells (C060) (12). In this system SV40 amplification can be monitored by molecular hybridization. Exposure of these cells to a variety of chemical and physical carcinogens has been shown to result in the amplification of SV40 DNA sequences. This amplification requires an active origin of replication and a functional T antigen. The amplification phenomenon is transient, reaching a maximal level on the third and fourth day after treatment with carcinogen, and disappears within a few more days (12,14,15). Exposure to carcinogens is followed by a prolonged S phase. Treatment of a synchronized population of cells obtained by isoleucine starvation results in increased SV40 amplification (Y. Berko and S. Lavi, manuscript in preparation).Further studies in our laboratory revealed transient amplification of additional DNA sequences including the dhfr and rasH genes in response to carc...

Background Chronic obstructive pulmonary disease (COPD) is an inflammatory disease characterized by a progressive and irreversible deterioration of lung function. Exacerbations of COPD have prolonged negative effects on pulmonary function and a major impact on health status and outcomes. NLRP3 inflammasome is a cardinal component of the inflammatory response, with marked evidence in stable and exacerbations of COPD. The aim of our study was to evaluate the NLRP3 inflammasome activity during COPD exacerbation by using an in vitro model. Methods A549 cells were stimulated with different concentrations (10%, 4%, 2%) of cigarette smoke extract (CSE) with or without LPS (0.1μg/ml) for 24 hours. Cell viability was assessed by using XTT test. Levels of inflammatory cytokines (IL-8, MCP-1, and IL-1β) were measured by ELISA and the activity level of NLRP-3 was evaluated by flow cytometry. Results Cells exposed to CSE present an increase in inflammatory cytokines (IL-8 and MCP-1) production in a dose-dependent manner. Incubation with LPS to these cells results in higher levels of IL-8 and MCP-1 compared to stimulation of CSE alone. NLRP3 inflammasome activity and IL-1β levels were significantly increased in cells exposed to both CSE and LPS compared to CSE alone. Conclusions NLRP3 inflammasome is upregulated in an in-vitro model of COPD and COPD exacerbation. Our findings provide novel biomarkers for COPD exacerbation and may present new targets for future research.

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We report a new mechanism of carcinogen action by which the expression of several genes was concomitantly enhanced. This mechanism involved the altered activity of cellular factors which modulate the expression of genes under their control. The increased expression was regulated at least in part on the transcriptional level and did not require amplification of the overexpressed genes. This phenomenon was transient; it was apparent as early as 24 h after carcinogen treatment and declined a few days later.

The clinical efficacy of topical 0.03 % tacrolimus was similar to 0.1 % dexamethasone for acute allergic conjunctivitis.

Background: The prevalence of peanut allergy (PA) is constantly on the rise. Atopic dermatitis (AD) is a major risk factor for developing food allergy. Some bath oils and skin creams used for treating AD contain peanut oil, and it has been suggested that exposure to peanut allergens through a disrupted skin barrier is a potential cause of PA. Our aim was to investigate whether application of peanut oil to irritated skin causes a systemic or respiratory allergic response to peanuts in an animal model. Methods: BALB/c mice underwent epicutaneous sensitization with either peanut oil (PM, n = 9) or phosphate buffered solution (controls, n = 9) daily for 5 consecutive days. Ten days after the last exposure the mice were challenged with intranasal peanut protein for 5 consecutive days. Bronchial alveolar lavage fluid was collected for cellular studies and measurement of cytokine levels. Sera were collected for immunoglobulin E (IgE) measurement. Results: Epicutaneous peanut oil sensitization increased leukocyte and eosinophil counts and interleukin-13 levels (p = 0.003, p = 0.0006 and p = 0.03, respectively), in addition to increasing total serum IgE (p = 0.03). Conclusions: The results suggest that topical application of peanut oil may play a role in the etiology of PA.

We have investigated different parameters characterizing carcinogen-mediated enhancement of methotrexate resistance in Chinese hamster ovary (CHO) cells and in simian virus 40-transformed Chinese hamster embryo (C060) cells. We show that this enhancement reflects dihydrofolate reductase (dhfr) gene amplification. The carcinogens used in this work are alkylating agents and UV irradiation. Both types of carcinogens induce a transient enhancement of methotrexate resistance which increases gradually from the time of treatment to 72 to 96 h later and decreases thereafter. Increasing doses of carcinogens decrease cell survival and increase the enhancement of methotrexate resistance. Enhancement was observed when cells were treated at different stages in the cell cycle, and it was maximal when cells were treated during the early S phase. These studies of carcinogen-mediated dhfr gene amplification coupled with our earlier studies on viral DNA amplification in simian virus 40-transformed cells demonstrate that the same parameters characterize the amplification of both genes. Possible cellular mechanisms responsible for the carcinogen-mediated gene amplification phenomenon are discussed.