Oncogenic viruses: of marmots and men
Article Abstract:
There is a strong epidemiologic relationship between hepatitis B infection and hepatocellular carcinoma, a form of liver cancer; carriers of hepatitis B virus are between 100 and 200 times more likely to develop hepatocellular carcinoma than persons who do not carry the virus. In parts of the world where hepatitis B infection is endemic, hepatocellular carcinoma is one of the most common of all cancers. However, the actual mechanism by which hepatitis B influences the development of cancer is far from clear. Hepatitis B virus does not seem to have an oncogene, a cancer-causing gene found in many cancer-causing viruses. Furthermore, the development of cancer may follow the initial hepatitis B infection by 20 or 30 years, suggesting that more complex abnormalities of cellular regulation may be at the core of the disease. The woodchuck, or marmot, turns out to be a useful animal in the study of hepatitis and liver cancer. Woodchucks are among the few animals subject to infection by viruses similar to human hepatitis B. Woodchucks infected at birth with woodchuck hepatitis virus are virtually guaranteed to develop hepatocellular carcinoma. Research has now indicated that, in the woodchuck, the viral DNA seems to prefer to incorporate itself into the woodchuck genome near a cellular gene called N-myc, a gene related to oncogenes. Researchers are excited about the possibility that the virus may act by altering the regulation of a cellular gene rather than by carrying its own oncogene. However, some researchers theorize that an entirely different mechanism may be at work. They believe that any condition which involves inflammation of the liver, such as hepatitis, also involves the proliferation of liver cells to compensate for the damage. This proliferation could set the stage for other events, which may ultimately result in cancer. In this model, the virus causes cancer only indirectly, by causing inflammation. Of course, there seems to be no reason why genetic and inflammatory mechanisms cannot both be at work simultaneously. One thing is certain, however; the finding that hepatitis virus genes can activate a woodchuck oncogene will no doubt stimulate the exploration of human cells infected with hepatitis B for a similar phenomenon. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1990
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More power to new mothers
Article Abstract:
UK law allows new mothers who are unable to return to work from maternity leave on the agreed date because of illness to postpone the date by up to four weeks as long as an appropriate medical certificate is presented. However, problems can arise if a new mother still cannot return to work because of illness after this time. Two recent cases in the Court of Appeal have made it clear that the right to return to work is granted to women once they have produced a written note of their maternity and return dates. The woman does not forfeit this right if she is not physically present at work.
Publication Name: Health & Safety at Work
Subject: Human resources and labor relations
ISSN: 0141-8246
Year: 1998
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Margot Fonteyn: a personal tribute
Article Abstract:
The career of Margot Fonteyn is chronicled. A dancer who spent six years with Fonteyn in the Sadler's Wells Ballet fondly recalls working with the beloved ballerina.
Publication Name: Dance Chronicle
Subject: Arts, visual and performing
ISSN: 0147-2526
Year: 1991
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