Prevalence of viral, bacterial and parasitological diseases in rats and mice used in research environments in Australasia over a 5-y period.

Viral, bacterial and parasitological infections in rats and mice used in biomedical research continue to occur despite improved housing and biosurveillance. The presence of disease in laboratory animals can lead to spurious results for research undertaken in universities, research institutes and the pharmaceutical industry. Here the authors report the results of serological, microbiological, parasitological and molecular tests done on mice and rats from Australasia submitted to a rodent health monitoring laboratory (Cerberus Sciences) from 2004 to 2009. In tested mice, norovirus was the most prevalent virus and ectromelia virus was the least prevalent virus. In tested rats, pneumonia virus of mice was the most prevalent virus and adenoviruses 1 and 2 were the least prevalent viruses. In mice, Helicobacter hepaticus was the most prevalent bacterium, and in rats, Proteus spp. were the most prevalent bacteria. The most common positive helminthological finding in mice and rats was the presence of all pinworms (including Aspicularis spp. and Syphacia spp.). The most common positive protozoan findings in mice and rats were Chilomastix spp. and Trichomonads.

Long-term exposure of E-mu-Pim1 transgenic mice to 898.4 MHz microwaves does not increase lymphoma incidence.

A total of 120 E mu-Pim1 heterozygous mice and 120 wild-type mice were exposed for 1 h/day 5 days/week at each of the four exposure levels in "Ferris-wheel" exposure systems for up to 104 weeks to GSM-modulated 898.4 MHz radiation at SARs of 0.25, 1.0, 2.0 and 4.0 W/kg. In addition, 120 heterozygous and 120 wild-type mice were sham-exposed; there was also an unrestrained negative control group. Four exposure levels were used to investigate whether a dose-response effect could be detected. Independent verification confirmed that the exposures in the current study were nonthermal. There was no significant difference in the incidence of lymphomas between exposed and sham-exposed groups at any of the exposure levels. A dose-response effect was not detected. The findings showed that long-term exposures of lymphoma-prone mice to 898.4 MHz GSM radiofrequency (RF) radiation at SARs of 0.25, 1.0, 2.0 and 4.0 W/kg had no significant effects when compared to sham-irradiated animals. A previous study (Repacholi et al., Radiat. Res. 147, 631-640, 1997) reported that long-term exposure of lymphoma-prone mice to one exposure level of 900 MHz RF radiation significantly increased the incidence of non-lymphoblastic lymphomas when compared to sham-irradiated animals.

Effect of long-term mobile communication microwave exposure on vascular permeability in mouse brain.

AIMS: To study the effect of long-term exposure to global system for mobile communication (GSM) radiofrequency fields on vascular permeability in murine brains. METHODS: Using a purpose-designed exposure system at 900 MHz, mice were given a 60-minute far-field, whole body exposure on each of 5 days per week for 104 weeks at specific absorption rates (SAR) of 0.25, 1.0,2.0 and 4.0 W/kg. Control mice were sham-exposed or permitted free movement in a cage to evaluate any stress-related effects. Albumin immunohistochemistry was used to detect increased vascular permeability and the efficacy of the vascular tracer was confirmed with a positive control group exposed to a clostridial toxin known to increase vascular permeability in the brain. RESULTS: In all exposed and control groups, albumin extravasation was minimal, often leptomeningeal, and was deemed insignificant as a maximum of three capillaries or venules in a given brain showed leakage from the very many blood vessels present in the three coronal brain sections. CONCLUSIONS: These results suggest that prolonged exposure to mobile telephone-type radiation produces negligible disruption to blood-brain barrier integrity at the light microscope level using endogenous albumin as a vascular tracer.