Spontaneous neoplastic lesions in aged Sprague-Dawley rats.

Neoplastic lesions were observed in untreated aged Sprague Dawley (SD) rats throughout their lifespan starting at 5 weeks. Their mean survival times were 89 to 105 weeks of age. The total tumor incidences were 70 to 76.7% and 87 to 95.8% in males and females, respectively. The common neoplasmas were pituitary adenoma and adrenal pheochromocytoma in both sexes, testicular Leydig cell tumor in males and mammary gland tumors, thyroidal C-cell adenoma and uterine stromal polyp in females.     

Spontaneous glomerular immunoglobulin deposition in young Sprague-Dawley rats

The frequency, age-onset and distribution of spontaneously deposited immunoglobulins (Igs) in glomeruli of Sprague-Dawley rats has been investigated. Groups of rats (n = 10) were examined at 4-7 day intervals from birth (presuckling) until 30 days of age. Findings were compared with circulating immunoglobulin concentrations in each age group. Immunoglobulins were undetectable in immature kidneys of newborn rats. However, as early as 5 days, scanty IgA and IgM deposits were observed predominantly in mesangial areas of mature glomeruli, corresponding to low circulating concentrations of these immunoglobulins. By contrast, glomerular IgG deposits were not observed until 21 days, despite relatively high concentrations of circulating maternal IgG from birth. Mesangial deposition of immunoglobulins increased with age. Absence of complement C3c or electron dense deposits associated with this mesangial localization suggests that immunoglobulins were not deposited as immune complexes. Accumulation of non-phlogogenic immunoglobulins in the mesangium of normal rats supports the concept that the mesangium is constantly perfused by circulating macromolecules and filtration residues. The results indicate problems of interpretation of the significance of endogenous immunoglobulin deposition in models of experimental glomerulonephritis, even in studies involving weanling rats.     

Hypoplasia of the adenohypophysis in a Sprague-Dawley rat

Pathological examination performed on a male 70-day-old Sprague-Dawley rat revealed formation of a large cyst in the hypophysis. The cyst, which completely occupied the adenohypophyseal area, was lined by the epithelial cells. Small masses of the adenohypophyseal cells were occasionally seen to sprout from the cyst wall epithelium.     

Hypoplasia of one kidney in a Sprague-Dawley rat

Pathological examination of a 4-week-old male Sprague-Dawley rat revealed hypoplasia of the left kidney. Grossly, the left kidney exhibited hypoplasia associated with absence of the ureter on the same side. Histologically, components of the cortex and medulla were mingled in the tissue, and the glomeruli and convoluted tubules were scattered in disorder, and connective tissue proliferation was also observed. The papilla and pelvis could not be identified.     

Spontaneous polar anterior subcapsular lenticular opacity in Sprague-Dawley rats

A spontaneous focal polar anterior subcapsular lenticular opacity characterized by focal epithelial proliferation was found in Charles River Sprague-Dawley rats from various breeding facilities around the world (France, Japan, and the United States). The incidence of this change slightly increased with age up to a maximal incidence of 9.8% in 28- to 35-week-old male rats (French source). Over that period, there was little change in the size of the opacity; however some rats that were examined over longer periods (more than 2 years of age) developed secondary anterior cortical changes, and rarely, histologic findings of pigmentation and/or mineralization. The lenticular change was present throughout the life of the animals and had no sex predilection; mode of inheritance was not investigated. Due to its small size, this lens opacity is more easily identified by use of slit lamp biomicroscopy than by use of indirect ophthalmoscopy, and serial sections of the eye aid in locating it for histologic evaluation.     

Predicted SAR in Sprague-Dawley rat as a function of permittivity values

Specific absorption rate (SAR) value is dependent on permittivity value. However, variability in the published permittivity values for human and animal tissue and the development of sophisticated 3-dimensional digital anatomical models to predict SAR values has resulted in the need to understand how model parameters (permittivity value) affect the predicted whole body and localized SAR values. In this paper, we establish the partial derivative of whole body SARs and localized SAR values (defined as SAR for individual organs with respect to a change in the permittivity values of all tissue types, as well as for those tissues with the most variable permittivity values. Variations in the published permittivity values may substantially influence whole body and localized SAR values, but only under special conditions. Orientation of the exposed object to the incident electromagnetic wave is one of the most crucial factors. Published 2001 Wiley-Liss, Inc.     

Pathology of sternal deformity in the Sprague-Dawley rat

Pathological examination of two 12-week-old male Sprague-Dawley rats revealed bending of the sternebrae. Grossly, the sternebrae distal to the third sternebra were bent towards the underside, and the episternal extremity was turned towards the head. Microscopically, the 4th sternebra was observed to have slipped behind the third sternebra, and fractures of the episternal cortex and slanting of the episternal cartilage were also observed.     

Antiobesity effect of recombinant human caseinomacropeptide in Sprague-Dawley rat

Caseinomacropeptide (CMP) is a glycopeptide of 64 amino acid residues derived from theC-terminal of mammalian milkk-casein. Recently, human CMP (hCMP) was produced from the recombinant yeastSaccharomyces cerevisiae. In this study, the antiobesity activity of the recombinant hCMP (rhCMP) was investigatedin vivo using Sprague-Dawley rats. The rhCMP did not affect the rats fed with a normal fat diet (fat content, 5.0%), but decreased the body weight gain of the rats fed with a high fat diet (fat content, 20%) by up to 19%. Autopsies revealed that the weights of the liver, kidney and adipose tissues decreased when the rats were given the rhCMP, which also reduced the lipid concentrations in the plasma and liver, but enhanced the fecal excretion of lipids. These results suggest that rhCMP prevent the accumulation of lipid by stimulating its fecal excretion, so could be used as a food supplement to alleviate the obesity problem caused by a high fat diet.     

Intraocular teratoma in a mouse

A 4.5-month-old male B6.129S2-Trp53tm1Tyj mouse developed an enlarged left eye. After euthanasia, the eye was removed and found to contain a teratoma composed of smooth muscle, white fat, neural tissue, and villous intestinal epithelium with appearance similar to that of the small intestine. Many normal intraocular structures were absent. To our knowledge, this represents the first reported intraocular teratoma in a mouse.     

Protein expression analysis of drug-mediated hepatotoxicity in the Sprague-Dawley rat

This study has investigated the protein changes in rat liver elicited by a group of model hepatotoxicants, methapyrilene, cyproterone acetate and dexamethasone and offers a compelling argument in support of the use of two-dimensional polyacrylamide gel electrophoresis and mass spectrometry for the identification of compound specific biomarkers. The different treatments caused distinct changes to the rat liver proteome. Many of the protein changes could be associated with the known pharmacological and toxicological mechanisms of action of these drugs, whereas for other proteins, the rationale behind the alterations was less obvious. Furthermore, these changes can be used to classify the treatments with a view to utilising them as 'molecular signatures' to further our understanding of less well studied drugs such as SKF-106686 (an adrenoreceptor agonist). This approach has the potential for opening up new avenues for the exploration of molecular mechanisms of toxicity. This paper has explored the feasibility of proteomics to provide valuable information on the biochemical consequences elicited by hepatototoxic drugs.