1-5
Resistance to Infection of Guinea Pigs with a Rat Streptobacillus Moniliformis
by R. Boot, L. van de Berg, M.A. Koedam, J.L.Veenema & M. Vlemminx

A rat S. moniliformis strain was dosed, orally and nasally, to two groups of 12 guinea pigs aged 10-15 weeks and 4-5 weeks respectively. In the first experiment 3 animals were sacrificed 1, 2, 4 and 6 weeks after infection and S. moniliformis was detected by culture in one animal at 2 weeks and by PCR in two animals at 4 weeks. In the second experiment 4 animals were sacrificed 2, 4 and 6 weeks after infection and S. moniliformis was not detected by culture and PCR in any animal. Seroconversion to S. moniliformis was found from 2 weeks after infection in 3 of 12 and 7 of 12 guinea pigs respectively. Clinical signs and gross lesions in the ventral cervical area and the lungs were not observed in any animal. We conclude that guinea pigs seem difficult to infect with a rat S. moniliformis strain.

9-16
Behavioural Effects of the Shelter Design on Male Guinea Pigs
by A. Nordlund, L. Lidfors, A-S. Lindh & B. Ewaldsson

To improve the welfare of group-housed male guinea pigs during the acclimatization period, which is when social groups are formed, different designs of shelters were tested, one shelter having one entrance to a single compartment – a Box for group hiding – and the other having individual entrances to a compartment in the cage – a Garage for single hiding. Both were studied to evaluate whether they had any affect on the behavioral levels. Behavioural and weight data were collected during five of the seven days of the acclimatization period. Data were tested against the Mann-Whitney U and Variance Analysis test. Results demonstrated that males in cages with the garage spent more time inside the shelter (P=0.0004), while males in cages with the box spent more time resting (P=0.000), feeding (P=0.0043) and drinking (P=0.0022) on the open floor, and yet there was no difference in individual weight between treatments at the end of the study. Males in cages with garage experienced a more rapid establishment of the social hierarchy (P=0.0024) by being involved with a lower number of social interactions. The conclusion from the present study is considered to show that males in cages with the garage were able to avoid unnecessarily high levels of stress and aggression caused by territorial defence while the hierarchy was established.

22-29
The use of High-Fat/Carbohydrate Diet-Fed and Streptozotocin-Treated Mice as a Suitable Animal Model of Type 2 Diabetes Mellitus
by Ji-hong Lian, You-qing Xiang, Lei Guo,Wei-rong Hu,Wei Ji & Bang-qiang Gong

This study defined a mouse model of type 2 diabetes that closely simulated the development and metabolic abnormalities of the human disease. Male C57BL/6J mice were fed with diet enriched in fat and simple carbohydrate for 6 weeks and then injected with streptozotocin (STZ, 150 mg/kg intraperitoneally) to develop type 2 diabetes. High-fat/carbohydrate-fed mice showed similar blood glucose concentrations to chow-fed mice, but higher insulin concentrations (P<0.01). Hyperglycemia (17.6±3.27 mmol/L) was observed in these mice after STZ injection, and the insulin concentrations decreased to the level comparable to, or still higher than, the normal. The model mice showed impaired glucose tolerance in the oral glucose tolerance test (OGTT), and insulin resistance in the insulin tolerance test (ITT). Moreover, these animals had lower glycogen storage (P<0.001), higher serum free fatty acid (P<0.001), and higher triglycerides (P<0.05) levels compared with control mice. Furthermore, the model mice were sensitive to the glucose lowering effect of metformin. In conclusion, this mouse model could be considered as one of the suitable animal models for type 2 diabetes mellitus, and hence can reasonably be used for type 2 diabetes pathophysiological research and therapeutic-compound evaluation.

35-41
Induction of Changes Over time in the Rat Proximal Femur Following Ovariectomy: A Model with Clinical Implications
by Wang Jianwei, Xu Shaowen,Yang Disheng & LV Rongkun

The menopause-related expansion of the proximal femoral marrow cavity is thought to have implications for the long-term cohesion of hip prostheses. This theory would be further strengthened if there was evidence to show that the expansion of the proximal femur marrow cavity takes place after the occurrence of a femoral neck fracture, which, it is often recommended, should be fixed with a hip prosthesis. But till now, the temporal relationship between those two osteoporotic-related changes has not been checked carefully. The objective of the current study was to examine the temporal relationship between the marrow cavity expansion of the proximal femur and the biomechanical deterioration of the femoral neck in a rat model. To do so, a cross-sectional study with multiple time points was carried out on 6-month old Sprague-Dawley rats, which were ovariectomized or sham-operated (as controls). The biomechanical properties of the femur neck and geometrical parameters of the femur shaft were evaluated at 0, 3, 6, 9, 12, 15, 18, and 21 weeks postoperatively, with special reference to the timescale of the observed changes. We found that the maximum load of the femoral neck in ovariectomized rats could bear decreased significantly compared, to that of controls, at 9 weeks postoperatively (p=0.03), while the marrow cavity of the proximal femur in ovariectomized rats turned out to be significantly enlarged at 15 weeks postoperatively (p=0.04). Conclusion: Our result demonstrated that the osteoporosis-related marrow-enlarged posterior led to the collapse of femoral neck strength. If the change in postmenopausal women is analogous to that in ovariectomized rats, the menopause-related marrow cavity expansion would be a risk factor for the longevity of hip prostheses.

47-58
Microbiological Control of Murine Viruses in Biological Materials: Methodology and Comparative Sensitivity. A review
by E Mahabir, M Brielmeier & J Schmidt

Introduction of microbiologically contaminated materials into mice can cause infections and distort research results. As counter measures, biological materials should be routinely screened prior to use, ideally by specific, sensitive, and reliable diagnostic methods. In this overview, we present a description of the currently used detection methods for murine viruses, including virus isolation in cell culture, the mouse antibody production (MAP) test, infant mouse bioassay and the PCR, that are relevant to routine health monitoring and summarize available data on their comparative sensitivities. Current diagnostic trends toward increased use of in vitro methods, apart from providing sensitive and specific results, contribute to refinement, replacement and reduction of the use of laboratory animals.