In vivo
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Fentanyl, a surgical analgesic and general anaesthetic, is a lipophilic short-acting synthetic opioid, having a selective potent effect on mu receptors. The transdermal therapeutic fentanyl-system (TTS-F) allows for a continued and sustained titratable amount of fentanyl to be delivered without the inconvenience of the typical 24-h administration of other analgesics. ⋯ More recent data indicates that TTS-F is not only effective for neuropathic but also nociceptive non-cancer and cancer pain alike. This review presents an overview of the synthesis, delivery, pharmacokinetics, toxicity and clinical pharmacology of the transdermal delivery of fentanyl.
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Nitric oxide and other reactive nitrogen species appear to play crucial roles in the brain such as neuromodulation, neurotransmission and synaptic plasticity, but are also involved in pathological processes such as neurodegeneration and neuroinflammation. Acute and chronic inflammation result in increased nitrogen monoxide formation and nitrosative stress. It is now well documented that NO and its toxic metabolite, peroxynitrite, can inhibit components of the mitochondrial respiratory chain leading to cellular energy deficiency and, eventually, to cell death. ⋯ These findings have led to new perspectives in medicine and pharmacology, as molecules inducing this defense mechanism appear to be possible candidates for novel, cytoprotective strategies. Particularly, manipulation of endogenous cellular defense mechanisms such as the heat shock response, through nutritional antioxidants or pharmacological compounds, represents an innovative approach to therapeutic intervention in diseases causing tissue damage, such as neurodegeneration. Consistent with this notion, maintenance or recovery of the activity of vitagenes may possibly delay the aging process and decrease the occurrence of age-related diseases with resulting prolongation of a healthy life span.
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Next to water, tea is the most popular beverage in the world, and the cancer-preventive effects of this beverage have been suggested. Epidemiological studies have shown decreased cancer occurrence in those individuals who drink green tea regularly. A wealth of research suggests numerous mechanisms of action to explain these observations. ⋯ Tea polyphenols have also been found to inhibit some cancer-related proteins that regulate DNA replication and transformation. At present, it is not known which of these activities of tea polyphenols are required for its cancer-preventive effects. However, by understanding the in vivo concentrations of tea polyphenols required to inhibit each of these activities, we may start to sort out in the future the mechanisms responsible for the cancer-preventive effects of tea.
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Cyclooxygenase-2 (COX-2), the inducible cyclooxygenase isozyme involved in the conversion of arachidonic acid (AA) to biologically active prostanoids, has become the subject of intense interest during the last few years. The recent surge of interest stems from seminal studies that correlated elevated expression of COX-2 with tumor induction and progression, and epidemiological studies that correlated reduced risk of developing certain types of cancers with chronic use of non-steroidal anti-inflammatory agents (NSAIDs). Although these observations were first reported with colorectal cancer (CRC), similar findings have subsequently been made with other types of cancers. ⋯ The aim of this article is to present a review of COX genes, the prostaglandin-cyclooxygenase relationship, the role of COX-2 in carcinogenesis and the rationale for targeting COX-2 with NSAIDs for cancer chemoprevention. Special emphasis is given to the role of COX-2 expression in the genesis and progression of colorectal neoplasia, and its correlation with other pathological characteristics of CRC. Preliminary observations on COX-2 expression in inflammatory bowel disease (IBD)-related colorectal neoplasia are also presented.
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Review Case Reports
The nature of tamoxifen action in the control of female breast cancer.
Tamoxifen, now in use in the breast cancer clinic worldwide, was a study subject of controversy showing an estrogenic property on one occasion and an anti-estrogenic property on another occasion. The outcomes of 4 case-control studies of tamoxifen use were disclosed through 4 publications in 1998. The contents of these reports were intriguing, not only to surgeons of breast cancer clinics, but also to researchers of oncological science in general. ⋯ All these observations provide strong support to the concept of the steroid criminal theory of human carcinogenesis in general. On the basis of both tamoxifen data and other information surrounding the hormonal aspect of human carcinogenesis of multiple tumors including breast cancer, we propose that the steroid generating system, as linked to the ever changing environment, plays a cardinal role as the transmitter of steroidal signals that can be taken as a "go" sign by the local oncogene-tumor suppressor gene complex of one target tissue and as a "stop" sign by that of another target tissue. The fitness of the tamoxifen data to the steroid carcinogenesis concept was discussed in the light of experimental pathology of chemical carcinogens, including the mammocarcinogen 7,12-dimethyl-benz(a)anthracene.