Best Practice Approach for Assessment of Microchip-associated Tumors in Preclinical Safety Studies: Position of the Registry of Industrial Toxicology Animal-data (RITA).

Microchip (passive radio-frequency identification device) implantation is a common and widely employed means of animal identification in laboratory animal facilities. However, these devices have been associated with tumors of the skin and subcutis in rodents. While microchip-associated tumors are rare, they pose a challenge for accurate diagnosis and documentation in preclinical toxicity studies. Documentation of these tumors should differentiate microchip-associated lesions with spontaneously occurring or test article-induced tumors. Standardizing criteria for microchip-associated lesions will aid the diagnostic process and allow for preclinical regulatory standardization. To this end, the Registry of Industrial Toxicology Animal-data have developed clear recommendations for diagnosis and documentation of microchip-associated lesions.

Proliferative and nonproliferative lesions of the rat and mouse urinary system.

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying lesions observed in the urinary tract of rats and mice. The standardized nomenclature of urinary tract lesions presented in this document is also available electronically on the Internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous developmental and aging lesions as well as those induced by exposure to test materials. A widely accepted and utilized international harmonization of nomenclature for urinary tract lesions in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Proliferative and nonproliferative lesions of the rat and mouse male reproductive system.

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature and differential diagnosis for classifying microscopic lesions observed in the male reproductive system of laboratory rats and mice, with color microphotographs illustrating examples of some lesions. The standardized nomenclature presented in this document is also available for society members electronically on the Internet (http://goreni.org). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and aging lesions as well as lesions induced by exposure to test materials. A widely accepted and utilized international harmonization of nomenclature for lesions of the male reproductive system in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Vasopeptidase inhibition prevents nephropathy in Zucker diabetic fatty rats.

BACKGROUND: Blocking the renin-angiotensin system is an established therapeutic principle in diabetic nephropathy. We investigated whether inhibition of both neutral endopeptidase and ACE (vasopeptidase inhibition) can prevent functional and morphological features of nephropathy in the Zucker diabetic fatty (ZDF) rat, an animal model of type II diabetes. METHODS: Homozygous (fa/fa) ZDF rats (each n=15) aged 10 weeks were treated with placebo, ramipril (1 mg/kg/day in drinking water), or the vasopeptidase inhibitor AVE7688 (45 mg/kg/day in chow). Metabolic parameters and renal function (metabolic cages) were assessed at baseline (age 10 weeks), and at age 17, 27, and 37 weeks. Twenty heterozygous animals (fa/-) served as lean, nondiabetic controls. At age 37 weeks, the animals were sacrificed and the kidneys analyzed histopathologically. RESULTS: Overt diabetes mellitus (blood glucose >20 mmol/l) was established at age 17 weeks in all homozygous ZDF rats. In the placebo group, urinary protein excretion increased progressively from 8+/-1 (baseline) to 342+/-56 mg/kg/day (week 37) whereas diabetes and proteinuria were absent in the lean control group. Ramipril tended to reduce albuminuria and morphological damage (p=ns) but AVE7688 virtually prevented albuminuria (33+/-12 mg/kg/day, p<0.05 vs. ZDF placebo) and drastically reduced the incidence and severity of glomerulosclerosis and tubulointerstitial damage. CONCLUSIONS: In ZDF rats, development of diabetes mellitus is accompanied by functional and morphological kidney damage that resembles human diabetic nephropathy. Diabetic nephropathy can be prevented by chronic vasopeptidase inhibition.

Revised guides for organ sampling and trimming in rats and mice--Part 3. A joint publication of the RITA and NACAD groups.

This is the third part of a series of three articles on trimming instructions of rat and mouse protocol organs and tissues in regulatory type toxicity studies, covering the urinary, nervous, musculoskeletal, cardiovascular, and lymphoreticular systems. The article is based on the experience of the European RITA and American NACAD working groups and is an extended revision of trimming guides published in 1995 (BAHNEMANN et al.). The optimum localization for tissue preparation, the sample size, the direction of sectioning and the number of sections to be prepared is described organ by organ. These descriptions are illustrated for each organ by a schematic drawing and/or a macro-photograph showing the plane of section as well as a low magnification of the H&E stained slide demonstrating the optimum "end-product". The objectives of this work, as addressed in detail in the first part (Ruehl-Fehlert et al. 2003), are to standardize tissue sampling and trimming for comparison of historical data obtained from different studies and different laboratories, ensure the presence of all relevant target sites for histopathological evaluation and provide technical advice for preparatory techniques during necropsy, fixation and trimming (Crissman et al. 2004).

Evaluation of the carcinogenic potential of insulin glargine (LANTUS) in rats and mice.

Insulin glargine (LANTUS) is a new, long-acting insulin analogue with a stable profile of action. The purpose of these studies was to evaluate the carcinogenic potential of insulin glargine in rats and mice. General toxicity studies were conducted in NMRI mice (3 months' duration) and rats (Wistar rats in the 3- and 6-month studies and Sprague-Dawley rats in the 12-month study) to determine the optimal dose of insulin glargine for long-term carcinogenicity studies. Based on these results, groups of Sprague-Dawley rats or NMRI mice (50 male, 50 female) received a daily subcutaneous dose of 2, 5, or 12.5 IU/kg of insulin glargine or 12.5 (mice) or 5 IU/kg (rats) of the reference insulin (NPH insulin) in a lifetime study. Similarly treated control and vehicle-control animals received isotonic sodium chloride (NaCl) solution or the vehicle solution, respectively. In mice, the mortality rate was comparable between all groups. In rats, the mortality rate compared with the NaCl control was significantly increased in the following groups: males treated with the vehicle control, all insulin glargine and NPH insulin groups, and in females in the high-dose insulin glargine and NPH insulin groups. There was no difference in the incidence of mammary tumors reported in both mice and rats when comparing the insulin glargine groups with the NaCl, vehicle-control, or the NPH insulin groups. In rats and mice, the distribution of subcutaneous malignant fibrous histiocytomas found at the injection site were not dose-dependent. These lesions are a rodent-specific event and were related to chronic tissue irritation and inflammation. In rats, neuronal necrosis of the cerebrum was attributed to persistent repeated episodes of hypoglycemia induced by high doses of insulin. In these studies, there were no neoplastic findings to indicate that insulin glargine had a systemic carcinogenic potential in mice or rats.