Visiting farms and ranches to experience agriculture and celebrate harvests is an age-old tradition. In the U.S. and many other countries, this tradition is the basis of an emerging industry known as "agritourism." Although agritourism appears to be growing in many parts of the U.S., confusion about agritourism limits the ability of researchers and agricultural interests to fully understand this sector's economic importance and to support its performance over time. A universal understanding of agritourism is needed for clear communication, reliable and consistent measurement, informed policies, and programs that support farms and ranches and their communities. To that end, the authors present a conceptual framework that incorporates core and peripheral tiers, as well as five categories of activities, including direct sales, education, hospitality, outdoor recreation, and entertainment. The goal of this viewpoint is to stimulate
Nitrosodiallylamine has been reported to be non-carcinogenic in rats while nitrosodipropylamine and nitrosodiethanolamine are liver carcinogens. That nitrosodipropylamine is metabolized at the alpha-position by liver microsomes from Fischer-344 rats supports the widely held contention that such metabolism is responsible for the carcinogenicity of nitrosamines. Nitrosodiallylamine is also metabolized at the alpha-position by the same microsomal preparations. Thus, although alpha-oxidation may be responsible for the carcinogenicity of some nitrosamines, this mechanism alone cannot account for tumorigenicity. Nitrosodiethanolamine is not metabolized by rat liver microsomes, but is metabolized by hepatocytes for Fischer-344 rats. In this case, a mechanism other than the oxidation at the alpha-position may be responsible for the carcinogenic action.
This open-label study enrolled five subjects with biopsy-proven cirrhosis and moderate to severe hepatic impairment (Child-Pugh classification grade B or C) and five age- and gender-matched controls. All subjects received a single 40-mg oral dose of stavudine (d4T). Stavudine pharmacokinetics in subjects with hepatic impairment were similar to those in age- and gender-matched control subjects and were not substantially different from those previously observed in human immunodeficiency virus-infected patients. Based on these findings, stavudine use does not require modification of the dose or dosing interval for patients with liver disease.
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