Testicular Mesotheliomas in Rats Exposed to N-2-Fluorenylacetamide (FAA)

1983 ◽  
Vol 69 (3) ◽  
pp. 195-199 ◽  
Author(s):  
J.R.P. Cabral ◽  
G.E. Neal
Keyword(s):  
Experimental Model ◽  
Control Diet ◽  
Fischer 344 Rats ◽  
Rat Strains ◽  
Chemical Carcinogens ◽  
Rare Type ◽  
Complete Cycle ◽  
Testicular Tumours ◽  
Fischer 344 ◽  
High Incidence

The incidence of testicular mesotheliomas after exposure to the carcinogen N-2-fluorenylacetamide (FAA) was studied in Fischer 344 rats. The animals were fed a carcinogenic diet (containing 0.06 % FAA) for 4 weeks and then a control diet for 1 week. This schedule was carried out for 3 complete cycles (12 weeks). A smaller group of rats was treated with FAA for 1 complete cycle only (4 weeks). One group of untreated controls was also available. The surviving rats were sacrificed at 59 weeks of age. The administration of FAA for 3 complete cycles resulted in a high incidence of liver, testis and Zymbal-gland tumors. The testicular tumours were mesotheliomas and occurred in 9/25 rats. No such tumour was observed in animals treated for 1 cycle only or in untreated controls. The high incidence of testicular mesotheliomas, a rare type of tumour in this and other rat strains, suggests an association with the treatment. The present experimental model may be useful in elucidating the mechanisms of the induction of mesothelial tumours of the testis by chemical carcinogens.

scholarly journals Induction and Reversibility of Thyroid Proliferative Changes in Rats Given an Antithyroid Compound

1986 ◽  
Vol 23 (2) ◽  
pp. 110-117 ◽  
Author(s):  
G. C. Todd
Keyword(s):  
Control Diet ◽  
Fischer 344 Rats ◽  
Test Compound ◽  
Follicular Cells ◽  
Prolonged Administration ◽  
Expected Effect ◽  
Fischer 344 ◽  
Nodular Hyperplasia ◽  
Size And Morphology ◽  
Behavior Supports

Sixty Fischer 344 rats were fed a diet containing 90 ppm methimazole, a known antithyroid compound. Following exposure to the test compound, groups of ten animals were terminated at 1, 3, and 6 months. Similar groups of ten treated animals were given control diet for a reversibility period of 2, 3, and 6 months, respectively. Groups of ten control rats were terminated after 1, 3, 6, and 12 months. Except for the expected effect on body weight, the treated animals had no physical signs of toxicity. The weight of thyroids increased with the duration of exposure, becoming in males after 6 months about ten times the weight of thyroids from control rats. Thyroids of treated rats after 1 and 3 months had a diffuse homogeneous hypertrophy and hyperplasia of follicular cells, decreased colloid, and increased vascularity. After 6 months' exposure to the antithyroid compound, there was diffuse hyperplasia but also a heterogeneity in the size and morphology of follicles, protrusion of follicular tissue through the gland capsule and into vascular spaces, and the development of follicular nodules. Treated rats placed on control diet, allowing for reversibility, had thyroids which were decreased in size with large follicles and flattened epithelium, and a complete remodeling of most nodules with no evidence of progression. Although the nodules produced after prolonged administration of the antithyroid compound had many of the characteristics of neoplasia, the biologic behavior supports the diagnosis of nodular hyperplasia.

scholarly journals The Quantification of Cerebral Infarction following Focal Ischemia in the Rat: Influence of Strain, Arterial Pressure, Blood Glucose Concentration, and Age

1988 ◽  
Vol 8 (4) ◽  
pp. 449-461 ◽  
Author(s):  
Danielle Duverger ◽  
Eric T. MacKenzie
Keyword(s):  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Experimental Diabetes ◽  
Focal Cerebral Ischemia ◽  
Artery Occlusion ◽  
Fischer 344 Rats ◽  
Rat Strains ◽  
Fischer 344 ◽  
Cerebral Artery Occlusion ◽  
Infarcted Tissue

Focal cerebral ischemia was induced by occlusion of the middle cerebral artery in rats. The volumetric assessment of infarcted tissue, 2 days following occlusion, was calculated from the examination of eight preselected coronal sections. Five differing rat strains were examined. A small and variable infarcted volume was seen in Wistar-Kyoto rats; Sprague-Dawley rats had a relatively large, but still variable, infarcted volume. Of the normotensive rat strains, the most reproducible volume of infarcted tissue was seen in Fischer-344 rats; also the absolute value of the infarcted volume did not vary from one series to another in this strain. Chronic arterial hypertension, studied in both normal and stroke-prone spontaneously hypertensive rats, was associated with significantly larger infarction volumes. Age does not change the volume of necrosis: Fischer-344 rats were studied at 3, 9, and 20 months of age, and no significant differences were noted between these ages. Experimental diabetes was induced by the administration of streptozotocin 3 days prior to middle cerebral artery occlusion. Severe hyperglycemia (>400 mg/dl) was associated with a considerably increased volume of infarction. The variability of the resultant lesion is high in the most commonly studied strains, but our results suggest that, for studies in normotensive rats, the use of the Fischer-344 strain produces a standardized and repeatable infarction that may be significantly modified by experimental interventions. Age is not a factor that affects the occlusion-induced infarction; in contrast, both chronic arterial hypertension and experimental diabetes aggravate the histological consequences of middle cerebral artery occlusion in the rat. We conclude that quantitative histological evaluation of infarct size allows a meaningful assessment of the gravity of focal cerebral ischemia.

Absence of sodium chloride preference in Fischer-344 rats

1985 ◽  
Vol 249 (4) ◽  
pp. R438-R442 ◽  
Author(s):  
E. E. Midkiff ◽  
D. A. Fitts ◽  
J. B. Simpson ◽  
I. L. Bernstein
Keyword(s):  
Wistar Rats ◽  
Inbred Strains ◽  
The Other ◽  
Fischer 344 Rats ◽  
Nacl Solution ◽  
Rat Strains ◽  
Taste System ◽  
Fischer 344 ◽  
Sodium Load ◽  
Direct Explanation

Preference for NaCl solutions as a function of concentration was examined in three inbred strains of rats (Munich-Wistar, Buffalo, and Fischer-344) and outbred Wistar rats. Fischer-344 rats were found to differ markedly from the other strains in that they failed to prefer any concentration of NaCl solution to water. This difference did not appear to be due to an insensitivity to the taste of NaCl since they significantly avoided solutions at concentrations (greater than 0.7%) that were strongly preferred by other rat strains. Differences between Fischer-344 and other rat strains also did not appear to be due to a generally anomalous taste system since their intake and preference for prototypes of other basic tastes (sweet, sour, and bitter) were generally similar to those of other strains. Although Fischer-344 rats were somewhat slower than Wistar to excrete a sodium load, it is unlikely that this difference can provide a direct explanation of the aversion of Fischer-344 rats for NaCl.

Morphological and Stereological Characterization of Hepatic Foci of Cellular Alteration in Control Fischer 344 Rats

1989 ◽  
Vol 17 (4_part_1) ◽  
pp. 579-593 ◽  
Author(s):  
Takanori Harada ◽  
Robert R. Maronpot ◽  
Richard W. Morris ◽  
Katherine A. Stitzel ◽  
Gary A. Boorman
Keyword(s):  
Clear Cell ◽  
Volume Fraction ◽  
Fischer 344 Rats ◽  
Mixed Cell ◽  
Fischer 344 ◽  
High Incidence ◽  
Hematoxylin And Eosin ◽  
Males And Females ◽  
F344 Rats

Quantitative evaluation of altered hepatocellular foci (AHF), followed by stereological analysis was performed on standard hematoxylin and eosin-stained liver sections from control Fischer 344 (F344) rats of both sexes from seven 2-yr carcinogenicity studies conducted by the National Toxicology Program (NTP). Liver samples were collected at 6, 9, 12, 15, 18, and/or 24 months on study. Although AHF had a broad spectrum of morphological features, they could be classified into the following 5 types using previously published criteria: basophilic, eosinophilic, clear, vacuolated, and mixed cell foci. Approximately 50% of the animals had foci at 6 months, and the incidence reached nearly 100% at 15 months in both sexes. The number, size and volume fraction of AHF increased with age in both sexes; these changes were most evident for basophilic and clear cell foci. The number of basophilic foci was significantly greater in females than in males while clear cell foci were more numerous in males. This sex difference was observed at each time point. Mean number of all types of AHF in males and females at 24 months was 547 and 460 per cubic centimeter of liver, respectively. Despite the high incidence of AHF in control rats, the incidence of hepatocellular neoplasms is low. The implication is that most foci do not progress to neoplasia in control F344 rats used in 2-yr studies.

In vivo cerebrovascular reactivity in Wistar and Fischer 344 rat strains during aging

1993 ◽  
Vol 264 (3) ◽  
pp. H851-H858 ◽  
Author(s):  
I. Lartaud ◽  
L. Bray-des-Boscs ◽  
J. M. Chillon ◽  
J. Atkinson ◽  
C. Capdeville-Atkinson
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Frontal Cortex ◽  
Blood Gases ◽  
Cerebrovascular Reactivity ◽  
Fischer 344 Rats ◽  
Rat Strains ◽  
Fischer 344 ◽  
Fischer 344 Rat

Basal cerebral blood flow (CBF) and CBF regulation after hypercapnia and hypotensive hemorrhage were investigated using H2 clearance in the frontal cortex of awake 2-, 14-, or 23-mo-old Wistar or Fischer 344 rats. Basal CBF decreased in old Wistar but not in mature Wistar (old 64.4 +/- 2.8, mature 87.6 +/- 2.6, young 79.6 +/- 2.2 ml.min-1 x 100 g-1) or in old Fischer 344 (old 71.9 +/- 2.9, young 73.3 +/- 1.6 ml.min-1 x 100 g-1) rats. Cerebrovascular reactivity to hypercapnia decreased in mature and old Wistar (old 2.1 +/- 0.3, mature 3.1 +/- 0.7, young 7.0 +/- 2.1 ml.min-1 x 100 g-1 x mmHg-1) but not in old Fischer 344 rats (old 4.6 +/- 1.4, young 4.9 +/- 0.9 ml.min-1 x 100 g-1 x mmHg-1). The lower limit of CBF autoregulation increased by 20 mmHg during maturation and/or aging in the two strains. Because blood gases and pH evolved similarly in both strains, we postulate that differences in cerebrovascular structure and/or function explain the differences in CBF regulation in the older representatives of the two strains.

Toxic effects of inhaled DMMP on the kidneys of Fischer-344 rats

1987 ◽  
Vol 45 ◽  
pp. 880-881
Author(s):  
D.R. Mattie ◽  
C.J. Hixson
Keyword(s):  
Left Kidney ◽  
Inhalation Exposure ◽  
Electron Microscopic Examination ◽  
Exposure Period ◽  
Male Rats ◽  
Continuous Exposure ◽  
Fischer 344 Rats ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Fischer 344

Dimethylmethylphosphonate (DMMP) is a simple organophosphate used industrially as a flame retardant and to lower viscosity in polyester and epoxy resins. The military considered the use of DMMP as a nerve gas simulant. Since military use of DMMP involved exposure by inhalation, there was a need for a subchronic inhalation exposure to DMMP to fully investigate its toxic potential.Male Fischer-344 rats were exposed to 25 ppm or 250 ppm DMMP vapor on a continuous basis for 90 days. An equal number of control rats were sham-exposed. Following the 90-day continuous exposure period, 15 male rats were sacrificed from each group. Two rats from each group had the left kidney perfused for electron microscopic examination. The kidneys were perfused from a height of 150 cm water with 1% glutaraldehyde in Sorensen's 0.1M phosphate buffer pH 7.2. An additional kidney was taken from a rat in each group and fixed by immersion in 2.5% glutaraldehyde and 2% paraformaldehyde in 0.1M cacodylate buffer pH 7.4. A portion of the 9 kidneys collected for electron microscopy were processed into Epon 812. Thin sections, stained with uranyl acetate and lead citrate, were examined with a JEOL 100B Transmission Electron Microscope. Microvilli height was measured on photographs of the cells of proximal tubules. This data, along with morphologic features of the cells, allows the proximal convoluted tubules (PCT) to be identified as being S1, S2, or S3 segment PCT.

Ultrastructure of rat alveolar macrophages activated in situ by poly:IC

1987 ◽  
Vol 45 ◽  
pp. 768-769
Author(s):  
A. M. Klinkner ◽  
R. A. Weiss ◽  
A. Kelley ◽  
P. J. Bugelski
Keyword(s):  
Venous Blood ◽  
Intratracheal Instillation ◽  
Buffy Coat ◽  
Fischer 344 Rats ◽  
Blood Monocytes ◽  
Fischer 344 ◽  
Polyinosinic:Polycytidylic Acid ◽  
Macrophage Activator ◽  
Endogenous Peroxidase

Polyinosinic:polycytidylic acid is an inducer of interferon and a macrophage activator. We have found that intratracheal instillation of polyI:C (IT-pI:C) activates rat bronchoalveolar lavage cells (BAL) for a variety of functions. Examination of Giemsa stained, cytocentrifuge preparations showed that IT-pI:C induced a population of BAL not seen in resident BAL. The morphology of these cells suggested that they might be derived from blood monocytes. To test this hypothesis we have examined several populations of macrophages that had been stained for endogenous peroxidase activity as a marker of cells derived from the monocyte-macrophage lineage.Macrophages were obtained from Fischer 344 rats. Peritoneal exudate cells (PEC) were collected by lavage 4 days after i.p. injection of 20 ml 3% thioglycolate. Buffy coat monocytes were separated from venous blood from naive rats.

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