The German Mouse Clinic: a platform for systemic phenotype analysis of mouse models.

The German Mouse Clinic (GMC) is a large scale phenotyping center where mouse mutant lines are analyzed in a standardized and comprehensive way. The result is an almost complete picture of the phenotype of a mouse mutant line--a systemic view. At the GMC, expert scientists from various fields of mouse research work in close cooperation with clinicians side by side at one location. The phenotype screens comprise the following areas: allergy, behavior, clinical chemistry, cardiovascular analyses, dysmorphology, bone and cartilage, energy metabolism, eye and vision, host-pathogen interactions, immunology, lung function, molecular phenotyping, neurology, nociception, steroid metabolism, and pathology. The German Mouse Clinic is an open access platform that offers a collaboration-based phenotyping to the scientific community (www.mouseclinic.de). More than 80 mutant lines have been analyzed in a primary screen for 320 parameters, and for 95% of the mutant lines we have found new or additional phenotypes that were not associated with the mouse line before. Our data contributed to the association of mutant mouse lines to the corresponding human disease. In addition, the systemic phenotype analysis accounts for pleiotropic gene functions and refines previous phenotypic characterizations. This is an important basis for the analysis of underlying disease mechanisms. We are currently setting up a platform that will include environmental challenge tests to decipher genome-environmental interactions in the areas nutrition, exercise, air, stress and infection with different standardized experiments. This will help us to identify genetic predispositions as susceptibility factors for environmental influences.

Microbiological monitoring of laboratory mice and biocontainment in individually ventilated cages: a field study.

Over recent years, the use of individually ventilated cage (IVC) rack systems in laboratory rodent facilities has increased. Since every cage in an IVC rack may be assumed to be a separate microbiological unit, comprehensive microbiological monitoring of animals kept in IVCs has become a challenging task, which may be addressed by the appropriate use of sentinel mice. Traditionally, these sentinels have been exposed to soiled bedding but more recently, the concept of exposure to exhaust air has been considered. The work reported here was aimed firstly at testing the efficiency of a sentinel-based microbiological monitoring programme under field conditions in a quarantine unit and in a multi-user unit with frequent imports of mouse colonies from various sources. Secondly, it was aimed at determining biocontainment of naturally infected mice kept in an IVC rack, which included breeding of the mice. Sentinels were exposed both to soiled bedding and to exhaust air. The mice which were used in the study carried prevalent infectious agents encountered in research animal facilities including mouse hepatitis virus (MHV), mouse parvovirus (MPV), intestinal flagellates and pinworms. Our data indicate that the sentinel-based health monitoring programme allowed rapid detection of MHV, intestinal flagellates and pinworms investigated by a combination of soiled bedding and exhaust air exposure. MHV was also detected by exposure to exhaust air only. The IVC rack used in this study provided biocontainment when infected mice were kept together with non-infected mice in separate cages in the same IVC rack.

A high-performance liquid chromatographic method for the determination of 8-oxo-7,8-dihydro-2'-deoxyguanosine in urine from man and rat.

The renally excreted amount of 8-oxo-7,8-dihydro-2'-deoxyguanosine (oxo(8)dG) is a potential marker of oxidative DNA damage by reactive oxygen species. We have developed a high-performance liquid chromatographic (HPLC) method to determine oxo(8)dG in urine from humans and Wistar rats. First, 300 microl of filtered urine is prefractionated by solid phase extraction (BAKERBOND SPE C(18) Polar Plus column). Then, the HPLC separation of the fraction containing oxo(8)dG is performed using four HPLC columns (two cation exchange and two C(18) columns) in series with an automated column switching technique. Quantification of oxo(8)dG is performed by electrochemical detection (Coulochem II, ESA Inc.). Limit of detection was 0.4 nM oxo(8)dG. Recovery of oxo(8)dG added respectively in 11 or 8 concentration steps (range, 4-74 or 2-23 nM) to a pooled human or rat urine was 104.1 +/- 4.3 or 104.5 +/- 7.7%. Precision of sixfold analysis of a pooled human or rat urine carried out respectively on the same day was 2.2 or 2.4% relative standard deviation. Normal excretion rates of oxo(8)dG in healthy adult humans (five females, six males; body weight, 70.7 +/- 11 kg) and male Wistar rats (body weight, 309 +/- 13 g) were 281.7 +/- 179.1 and 333.2 +/- 47.4 pmol oxo(8)dG/day/kg weight, respectively.

Renal excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine in Wistar rats with increased O(2) consumption due to cold stress.

DNA damage by reactive oxygen species is of special interest in the development of cancer and in aging. The renally excreted amount of 8-oxo-7,8-dihydro-2'-deoxyguanosine (oxo(8)dG) is a potential noninvasive marker of oxidative DNA damage. The respiratory chain of mitochondria is one source for the formation of reactive oxygen species. In the present study we investigated in Wistar rats (n = 7; mean body weight at start, 307.4 +/- 11 g) the effect of an increased O(2) consumption, i.e., energy expenditure, due to cold stress on the renally excreted amount of oxo(8)dG. First, the rats were housed for 4 days at 23.5 degrees C (basic period, BP), and then for 6 days at 10 degrees C (cold stress period, CSP), and finally for 3 days at 23.5 degrees C (recovery period, RP). The O(2) consumption (L O(2)/day/kg weight) was significantly (P < 0.0001) on average 50% higher in CSP (69.0 +/- 3.9) than in BP (45.8 +/- 4.8), and similar in BP and RP (44.3 +/- 5.4). The average renal excretion of oxo(8)dG (pmol/day/kg weight) was significantly (P < 0.025) on average 13% higher in CSP (375.5 +/- 27.7) than in BP (333.2 +/- 47. 4) and similar in BP and RP (331.8 +/- 34.3). Maximum increase in oxo(8)dG excretion of on average 17% was on the third to fifth day of the CSP. This study reveals that an increase in O(2) consumption of 50% resulted in a much lower increase in the renal excretion of oxo(8)dG.