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Journal Article 2002; 23(4): 325-328 PubMed PMID: 12195235 Citation  Keywords:  Animals, Antineoplastic Agents:pharmacology, Astrocytes:cytology, Cerebral Cortex:cytology, DNA-Binding Proteins:metabolism, Gene Expression:drug effects, Glioma, Growth Inhibitors:pharmacology, Interferon-gamma:pharmacology, Interleukin-6:pharmacology, L.   

OBJECTIVES: The purpose of this study was to compare the effects of neurotrophic cytokines on the JAK/STAT transcription factors and the immediate early gene, c-fos, in C6 glioma cells and in primary astrocyte cultures.

METHODS: In this study we compared the effects of interleukin 6, leukemia inhibitory factor and interferon gamma on C6 glioma cells and on primary astrocyte cultures using electrophoretic mobility shift assay and quantitative solution hybridization/Northern Blot analysis.

RESULTS: We show that interleukin 6, leukemia inhibitory factor and interferon gamma treatment induce the nuclear STAT3 and STAT1 proteins to bind to the sis inducible element of c-fos in both C6 glioma cells and primary cortical astrocytes. Furthermore, quantitative solution hybridization and Northern blot analysis show the differential regulation of c-fos mRNA levels by interleukin-6 (8.1 and 4.0 folds) and leukemia inhibitory factor (5.4 and 3.2 folds) in C6 and astrocyte cultures (respectively). However, interferon gamma increases in c-fos mRNA levels (2.9 fold in both C6 and astrocyte cultures) were not significant in a one way ANOVA.

CONCLUSION: This study suggests that two initial cytokine signaling pathways are present and functional in C6 glioma cells and in primary astrocyte cultures....

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Congresses 2002; 23(Suppl 2): 4-104 PubMed PMID: 12163856 Citation  Keywords:  Animals, Endocrine System:physiology, Humans, Light:adverse effects, Neoplasms:etiology,.   

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Congresses 2002; 23(Suppl 2): 84-87 PubMed PMID: 12163855 Citation  Keywords:  Animals, Humans, Light:adverse effects, Neoplasms:epidemiology, Neurosecretory Systems:physiology, Risk Factors,.   

: The International Symposium "Light, Endocrine Systems and Cancer" was held on May 2-3 at Cologne University, Germany. The symposium was organized by Professor Claus Piekarski and Dr. Thomas C. Erren, Institute and Polyclinic for Occupational and Social Medicine. The main goal of the symposium was to evaluate the epidemiological and experimental data on the effect of the exposure to light-at-night on cancer risk and to indicate the main directions of future research in the field. The symposium covered also the mechanisms and epidemiology of skin cancer which, however, are not included in the present summary....

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Editorial 2002; 23(Suppl 2): 82-83 PubMed PMID: 12163854 Citation  Keywords:  Circadian Rhythm:physiology, Humans, Light:adverse effects, Neoplasms:epidemiology, Neurosecretory Systems:physiology, Risk Factors,.   

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Editorial 2002; 23(Suppl 2): 79-81 PubMed PMID: 12163853 Citation  Keywords:  Animals, Humans, Light:adverse effects, Neoplasms:epidemiology, Neurosecretory Systems:physiology, Risk Factors,.   

: A conference was held at the University of Cologne on May 2-3, 2002, to discuss the strength-of-the-evidence supporting a linkage between light, endocrine systems and cancer. This overview of the conference is intended to summarize some of the key elements of the conference and to indicate both conclusions and research gaps identified by this reviewer....

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Editorial 2002; 23(Suppl 2): 71-78 PubMed PMID: 12163852 Citation  Keywords:  Darkness, Decision Making, Humans, Light:adverse effects, Neoplasms:epidemiology, Neurosecretory Systems:physiology, Risk Factors,.   

: Research on light at night and cancer is evolving at an accelerating pace, fueled largely by exciting results in rodent toxicology and basic human biology. Epidemiologic research is at a relatively early stage of development in which the exposure surrogates such as shift work and blindness predominate. Causal graphs for shift work, light at night and breast cancer illustrate some of the subtleties that can arise in the use of exposure surrogates of different kinds. Baseline data on circadian rhythms and melatonin cycles among human populations living at different latitudes are needed. Epidemiologic study of this topic is expected to mature soon as studies begin to incorporate quantitative and semiquantitative measurements and personal histories of exposure to light at night. The current emphasis on breast cancer should widen to include other cancers and intermediate outcomes. An advance in epidemiologic studies of blind persons would be to compare cancer rates between the "cortically blind" and the "retinally blind" within levels of visual impairment. Without a proposed intervention to reduce exposure to light at night, attributable fraction and attributable caseload estimates are meaningless. In the near future, both epidemiologic and laboratory research in this area are expected to grow appreciably in scope and scale....

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Journal Article 2002; 23(Suppl 2): 61-70 PubMed PMID: 12163851 Citation  Keywords:  Environmental Exposure, Humans, Light:adverse effects, Melatonin:physiology, Neoplasms, Hormone-Dependent:etiology,.   

: Visible light of sufficient intensity and duration inhibits melatonin biosynthesis, and experimental studies suggest that melatonin may protect against cancer. From a public health point of view it is important to verify or falsify the hypothesis that artificial light--or even sunlight itself--suppresses melatonin production sufficiently to increase the risk of developing cancers of internal organs in man. Epidemiology is a discipline that can contribute to in-vivo verification of experimental findings. But when attempting to study the effects of light on man, epidemiologists are faced with a major problem: the ubiquitous nature of natural and anthropogenic light, which renders everyone, everywhere exposed. The challenge is to identify populations with demonstrable varying exposures to light. This paper summarizes how recent epidemiological investigations have sought to tackle the problem by studying shift-workers, blind people and Arctic residents. It is suggested that future studies should test the underlying assumptions regarding endocrine responses to light, i.e., that melatonin levels are reduced among shift-workers, and that they are increased among the blind and those who live in the Arctic. A systematic investigation of exposure-response relationships could be based on "light dosimetry by geography". Such a study is envisaged by European researchers who aim to study melatonin and other hormones in samples from healthy general populations that are differentially exposed to light by virtue of varying ambient photoperiods. Further methodologic options for prospective and retrospective epidemiologic studies are suggested. It is concluded that the biologically plausible link between ubiquitous light, hormones and the development of very frequent malignancies such as breast cancer and prostate cancer should be investigated rigorously by additional well-designed epidemiological research....

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Journal Article 2002; 23(Suppl 2): 57-60 PubMed PMID: 12163850 Citation  Keywords:  Breast Neoplasms:epidemiology, Circadian Rhythm, Female, Humans, Light:adverse effects, Lighting, Risk Factors,.   

: Risk of breast cancer varies by about 5-fold among societies, and incidence and mortality have been increasing worldwide for many decades. Migrants from low-risk Asian societies to the U.S. suffer elevated risk of breast cancer in their own lifetimes, and the second or third generation Asian-Americans attain the high risk of the multi-generational European immigrants [1,2]. Something about a modern Western lifestyle apparently increases risk dramatically. Madigan et al. [3] estimate that 41% of the new U.S. cases of breast cancer are explained by "known risk factors"; these include the reproductive factors of age at first birth, menarche, menopause. They ascribe about 30% to reproductive factors when they are analyzed alone. "High income" is estimated to account for about 19% when analyzed by itself. The 41% is an analysis taking all the factors together, and since they are related, the total is less than the sum of estimates for the individual items. By itself, "High income" has no biological interpretation and must reflect attributes of lifestyle and/or environment that increase risk. So, the proportion of breast cancer cases in the U.S. that can be accounted for by known biological risk factors is about one third. Therefore, at least half of breast cancer risk in the U.S., and other Westernized/industrialized societies, is in excess of that found in non-industrialized societies and is without any agreed-upon explanation. Many candidate factors exist, each with a cadre of proponents. The sum of these may turn out to explain the bulk of the excess risk in modern societies. On the other hand, they may not, and worse, may fall woefully short....

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