Tumours spontaneous

The comparison between groups of young and aged animals must take into account the effect of age-related physical incapacitation or behavioural performance (tumours, spontaneous sensorimotor changes, pain sensitivity, visual impairment). The fact that aged subjects are only one subgroup of the minority of the surviving animals also introduces a selection bias. 

METHODS USED FOR DETECTING ANTITUMOUR ACTIVITY Transplantable tumours Spontaneous tumours Induced tumours Heteroplanted human tumours Tissue culture techniques Antimicrobial tests... 

Association of Pain, neuropathic pain is defined as pain initiated or caused by a primary lesion, dysfunction in the nervous system". Neuropathy can be divided broadly into peripheral and central neuropathic pain, depending on whether the primary lesion or dysfunction is situated in the peripheral or central nervous system. In the periphery, neuropathic pain can result from disease or inflammatory states that affect peripheral nerves (e.g. diabetes mellitus, herpes zoster, HIV) or alternatively due to neuroma formation (amputation, nerve transection), nerve compression (e.g. tumours, entrapment) or other injuries (e.g. nerve crush, trauma). Central pain syndromes, on the other hand, result from alterations in different regions of the brain or the spinal cord. Examples include tumour or trauma affecting particular CNS structures (e.g. brainstem and thalamus) or spinal cord injury. Both the symptoms and origins of neuropathic pain are extremely diverse. Due to this variability, neuropathic pain syndromes are often difficult to treat. Some of the clinical symptoms associated with this condition include spontaneous pain, tactile allodynia (touch-evoked pain), hyperalgesia (enhanced responses to a painful stimulus) and sensory deficits. 

The most important comparison is with concurrent control groups. However, there are occasions when it is necessary to use historical data, that is, information from control animals of the same strain on other studies. This is more relevant if the studies were conducted in the same laboratory under similar conditions and at the same time. The incidence of a particular neoplasm is often different between laboratories and may change with time. Historical data are most useful to get an idea of the variation in the background range of frequency and also to ascertain that rare tumour t)rpes can occur spontaneously. 

In one inhalation study in rats, 1,3-butadiene increased the incidence of tumours at several sites. The tumour increases were mainly in organs in which tumours develop spontaneously. The response was seen mainly at 8000 ppm [17 700 mg/m ]. 

Groups of 60 male and 60 female Swiss mice, nine weeks of age, were exposed by inhalation to 0, 1000 or 5000 ppm [0, 3540 or 17 700 mg/m ] chlorodifluoromethane (FC 22 purity, 99.98%) for 4 h per day on five days per week for 78 weeks. The animals were kept under observation until spontaneous death [survival unspecificdj. Full necropsy was performed on all animals. No effects were found on survival or body weight. No difference related to treatment was found in the incidence of benign or malignant tumours (Maltoni et al., 1988). 

Hamster. Groups of 15 male and 15 female European hamsters (Cricetus cricetus) [age unspecified] were given weekly subcutaneous injections of 1/10 of the LD50 (LD50 373 mg/kg bw for males and 325 mg/kg bw for females) of 1,1-dimethylhydrazine in saline for life. A group of eight males and eight females served as controls. Hamsters were observed until spontaneous death. Six males and six females treated with 1,1-dimethylhydrazine developed peripheral nerve sheath tumours (neurofibrosarcoma. 

Donehower, L. A., M. Harvey, B. L. Slagle, M. J. McArthur, C. A. Montgomery, J. S. Butel, and A. Bradley, Mice deficient for p53 are developmentally normal but susceptible to spontaneous tumours. Nature 356 215-221, 1992. A remarkable new technique for obtaining null mutations demonstrates that embryogenesis is normal in the absence of p53. However, animals develop a variety of neoplasms in the first 6 months when p53 is lacking. 

Natural killer cell (NKC) Any class of white blood cells that can spontaneously recognize and kill tumour or virus infected cells without previous exposure to an antigen. NKC cytotoxicity decreased in depression and in alcoholism. 

However, experience has shown that the choice of other species is difficult due to lack of experience with other rodent species. The hamster could be considered, but there are only a few studies conducted or published in this species with the consequence of little information about spontaneous tumour incidences. 

Cushing s disease is caused by an increase in circulating ACTH, usually from a tumour either in the pituitary gland or at other body sites, or there maybe a spontaneous increase in release of cortisol. 

In 1969, Henry Harris, George Klein, and colleagues, reported that cancerous cells, which could produce tumours in animals, lost their tumorigenicity when they were fused with non-cancerous normal cells. The loss of tumorigenicity was then perpetuated from one generation to the next. This experiment was a landmark in cancer research. Many experiments that followed demonstrated that this condition applied to all kinds of cancers—virally induced, chemically induced, and spontaneous tumours—and to a variety of cell types—epithelial cells, fibroblasts, and lymphoc5rtes. 

By encapsulation of the drug in liposomes a favourable alteration of the pharmacokinetics, as well as a lowered toxicity, may be obtained. Even more important is the fact that liposomes collect spontaneously in areas of inflammation and in tumour tissue. This property, which is believed to be due to the inherently leaky vasculature in these areas, has led to the development of several liposomal anti-inflammatory and anticancer agents. 

Kaufmann, A. M., Lichtner, R. B., Schirrmacher, V. and Khazaie, K. (1996). Induction of apoptosis by EGF receptor in rat mammary adenocarcinoma cells coincides with enhanced spontaneous tumour metastasis. Oncogene 13, 2349-2358. 

Matzku, S. Krempel, H. Weckenmann, H.P. Schirrma-cher, V. Sinn, H. Strieker, H. Tumour targeting with antibody-coupled liposomes failure to achieve accumulation in xenografts and spontaneous liver metastases. Cancer Immunol. Immunother. 1990, 31, 285-291. 

Hilgard P, Schulte H, Wetzig G, Schmitt G, Schmidt CG. Oral anticoagulation in the treatment of a spontaneously metastasising murine tumour (3LL). Br J Cancer 1977 35(l) 78-86. 

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