This study involved the fact that knowledge of natural incidence neoplastic lesions is essential for interpretation experiments designed to reveal effects potential carcinogens. Although F344 rat widely used in chronic (2-yr) testing programs, history neoplasia after 24 months not known; thus this study, with 529 male and female inbred rats, was deal aspect. report also included information on growth longevity. In addition, tumor rates found were compared 2-year historic control rates;...

Focal brain ischemia induces inflammation, extracellular matrix remodeling, gliosis, and neovascularization. Osteopontin (OPN) is a secreted glycoprotein that has been implicated in vascular injury by promoting cell adhesion, migration, chemotaxis. To investigate the possible involvement of OPN remodeling after focal stroke, we examined expression ischemic cortex permanent or temporary occlusion middle cerebral artery (MCAO) rat. mRNA protein levels nonischemic were not detected...

A survey of non-neoplastic and neoplastic renal lesions found in 5 rat strains, namely, ACI (August x Copenhagen Irish), A22807 (August), F344 (Fischer), M520 (Marshall), OM (Osbome-Mendel) is given. The results from this indicate that the OM, M520, strains have major disadvantages for their use long-term toxicology carcinogenesis studies. Male rats had a high incidence renovascular which consisted necrotizing arteritis or arteriolitis intimal thickening small arteries, resembled described...

SummaryRadiation carcinogenesis of the rat mammary gland was investigated with objective investigating combined effect oestrogen administration and irradiation. Three strains, Sprague—Dawley, Wistar WAG/Rij Brown Norway, different susceptibilities to induction cancer, have been irradiated X-rays mono-energetic neutrons. Increased hormone levels were obtained by subcutaneous implantation pellets oestradiol-17β (E2). The tumour incidence results corrected for competing risks analysed a...

Abstract BACKGROUND: Idoxifene is a selective estrogen receptor modulator similar to tamoxifen but no longer in pharmaceutical development due adverse genitourinary effects the clinic. Histologic observations of reproductive system and mammary glands are presented from female dogs treated with idoxifene for up 12 months. METHODS: Studies were conducted as part regulatory requirements support clinical development. was given orally by capsule, once daily, 1, 6, or months Beagle (n = 3 4/group)...

In this study, results are presented which in agreement with predictions made on basis of the ‘three‐Stage hypothesis’ development benign monoclonal gammapathy (BMG). a T‐cell depletion model, C57BL/Ka nude mice were shown to develop single and multiple homogeneous immunoglobulins (H‐Ig) during aging highest frequencies known so far. Ninety percent displayed one or more H‐Ig at 12 months age. supplementation infusion corticosteroid resistant T cells into 9‐month‐old BALB/c resulted decrease...

Structurally and pharmacologically diverse vasodilators are known to lower blood pressure, increase heart rate, produce acute injury right coronary arteries in the dog. Administration of low concentrations endothelin-1 (ET-1) anesthetized dogs causes vasoconstriction reductions flow. Therefore, pharmacologic blockade endothelin receptors (ETA ETB) with mixed ET receptor antagonist SB 209670 could lead vasodilatation. In toxicology studies, continuous administration for 5 days at 50...

Proliferative vascular lesions of the heart were found in mice exposed chronically to 1,3-butadiene by inhalation with an overall incidence 30% males and 43% females. Based on histological criteria, subclassified as endothelial hyperplasia 7% 13% females hemangiosarcoma 23% 30%, respectively. A dose-relationship for both was observed females, but not males. The absence a dose response most likely due lower survival rate high-dose animals (14%) when compared lower-dose (22%). Endothelial...

This histopathological study shows that Mastomys develops a wide variety of neoplastic and nonneoplastic lesions with age. In comparing those generally found in mice rats, is more or less unique respect to the development lymphoepithelial thymomas (40%), parathyroid adenomas (11%), prostatic adenocarcinomas (5%), gastric carcinoids (4%) absence brain, lung, mammary tumors. Of lesions, (38%), thymic (12%) (11%) hyperplasia, moderate severe generalized degenerative joint disease (96%) occur...

Abstract We have developed a novel contrast agent, ytterbium‐diethylenetriamine pentaacetic acid (Yb‐DTPA), for magnetic resonance imaging (MRI) and its mechanism of action is predominantly by the susceptibility mechanism. applied this agent renal MRI studies. also demonstrate that Yb‐DTPA has clearance similar to inulin in rats may therefore be useful estimation glomerular filtration rate. © 1991 Academic Press, Inc.

Consideration is given to the age association of lesions, duration long-term toxicity and carcinogenesis studies, value significance including scheduled termination in such studies. There now enough evidence that cancer are associated. It argued increase incidence lesions with has disadvantages extension carcinogenicity study beyond 2 years not warranted most cases. Incorporation studies gives more insight into biologic behavior toxic may enable one make a distinction between "incidental"...

A macroscopic and histologic description of membranous dysmenorrhea in chimpanzees is given. The similarity these cases to those women make the chimpanzee an interesting model for studies on presently unknown etiology dysmenorrhea.