Characteristic features of newly established specific pathogen-free albino large rabbit (JW-AKT): Comparison with Japanese White and New Zealand White rabbits.

The present study was conducted to reveal characteristic features of albino large rabbit (JW-AKT) which we formerly established a specific pathogen-free (SPF) colony. Body weights of JW-AKT rabbit at 52 weeks old was 5.7 ± 0.4 kg in males and 6.4 ± 0.4 kg in females. Weight of body, heart, lung and kidney in JW-AKT rabbit was significantly higher than in Japanese white and New Zealand white rabbits in both sexes. Though the body weight (BW) was rather lower in males, body length and brain weights tended to be higher in males than in females. Since body fat was significantly higher in females, what affects difference in BW is body fat, rather than the physical constitution of female JW-AKT rabbit. No critical sex difference was found in hematological parameters in JW-AKT rabbit. The results indicated that JW-AKT were about 1.5 times larger than the general laboratory rabbits with common properties in hematology. Thus, JW-AKT rabbit could be used as a novel SPF experimental animal model with some advantages in surgical experiments or collection of large amount of biological specimen.

Effects of slightly acidic electrolysed drinking water on mice.

Slightly acidic electrolysed (SAE) water is a sanitizer with strong bactericidal activity due to hypochlorous acid. We assessed the safety of SAE water as drinking water for mice at a 5 ppm total residual chlorine (TRC) concentration to examine the possibility of SAE water as a labour- and energy-saving alternative to sterile water. We provided SAE water or sterile water to mice for 12 weeks, during which time we recorded changes in body weight and weekly water and food intakes. At the end of the experiment, all of the subject animals were sacrificed to assess serum aspartate aminotransferase, alanine aminotransferase and creatinine levels and to examine the main organs histopathologically under a light microscope. In addition, we investigated the bacteria levels of both types of water. We found no difference in functional and morphological health condition indices between the groups. Compared with sterile water, SAE water had a relatively higher ability to suppress bacterial growth. We suggest that SAE water at 5 ppm TRC is a safe and useful alternative to sterile water for use as drinking water in laboratory animal facilities.

Hyperplasia and carcinomas in Pten-deficient mice and reduced PTEN protein in human bladder cancer patients.

PTEN is a tumor suppressor gene mutated in many human cancers. We used the Cre-loxP system to generate an urothelium-specific null mutation of Pten in mice [FabpCrePten(flox/flox) (FPten(flox/flox)) mice]. Histologic examination revealed that all FPten(flox/flox) mice exhibited urothelial hyperplasia in which component cells showed enlarged nuclei and increased cell size. With time, 10% of FPten(flox/flox) mice spontaneously developed pedicellate papillary transitional cell carcinomas (TCC). This type of tumor also arose in FPten(flox/flox) mice treated with the chemical carcinogen N-butyl-N-(4-hydroxybutyl) nitrosamine. FPten(flox/flox) urothelial cells were hyperproliferative and showed increased activation of the survival signaling molecules Akt and extracellular signal-regulated kinase. In humans, 53% of primary bladder cancer patients exhibited decreased or absent expression of PTEN protein in either the cytoplasm or nucleus of tumor cells. In early bladder cancers, PTEN expression was repressed in 42% of superficial papillary TCC but in only 8% of cases of carcinoma in situ (CIS). In advanced bladder cancers, PTEN protein was significantly reduced (particularly in the nucleus) in 94% of cases, and this decrease in PTEN correlated with disease stage and grade. Thus, PTEN deficiency may contribute to bladder cancer both by initiating superficial papillary TCC and by promoting the progression of CIS to advanced invasive and metastatic forms.