Removal Of Mice Research Articles

Evaluation of Nutritional Gel Supplementation in C57BL/6J Mice Infected with Mouse-Adapted Influenza A/PR/8/34 Virus.

Mice are a common animal model for the study of influenza virus A (IAV). IAV infection causes weight loss due to anorexia and dehydration, which can result in early removal of mice from a study when they reach a humane endpoint. To reduce the number of mice prematurely removed from an experiment, we assessed nutritional gel (NG) supplementation as a support strategy for mice infected with mouse-adapted Influenza A/Puerto Rico/8/34 (A/PR/8/34; H1N1) virus. We hypothesized that, compared with the standard of care (SOC), supplementation with NG would reduce weight loss and increase survival in mice infected with IAV without impacting the initial immune response to infection. To assess the effects of NG, male and female C57BL/6J mice were infected with IAV at low, intermediate, or high doses. When compared with SOC, mice given NG showed a significant decrease in the maximal percent weight loss at all viral doses in males and at the intermediate dose for females. Mice supplemented with NG had no deaths for either sex at the intermediate dose and a significant increase in survival in males at the high viral dose. Supplementation with NG did not alter the viral titer or the pulmonary recruitment of immune cells as measured by cell counts and flow cytometry of cells recovered in bronchoalveolar lavage (BAL) fluid in either sex. However, mice given NG had a significant reduction in IL6 and TNFα in BAL fluid and no significant differences in CCL2, IL4, IL10, CXCL1, CXCL2, and VEGF. The results of this study show that as compared with infected SOC mice, infected mice supplemented with NG have reduced weight loss and increased survival, with males showing a greater benefit. These results suggest that NG should be considered as a support strategy and indicate that sex is an important biologic variable in mice infected with IAV.

NAFLD induces neuroinflammation and accelerates Alzheimer’s disease

Abstract Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease afflicting about one third of the world’s population and 30% of the US population. It is induced by consumption of high lipid diets and is characterized by liver inflammation and subsequent liver pathology leading to steatosis and steatohepatitis. We fed mice with high fat/lipid diet (HFD) or a standard diet (SD) and monitored them for signs of systemic or central nervous system inflammation. We found that NAFLD induced acute liver inflammation and accelerates signs of Alzheimer’s disease (AD) in an AD-Transgenic model. Moreover, chronic NAFLD induced advanced signs of AD in WT mice. In the chronic disease stage, we observed neuronal apoptosis and decreased brain expression of low-density lipoprotein receptor-related protein-1 that is involved in beta-amyloid clearance, in both WT and APP-Tg mice. HFD fed mice harbored numerous activated and proliferating microglial cells in their brain. Removal of mice from HFD during acute disease reversed liver pathology and neuroinflammation and decreased beta-amyloid plaque load. Concomitant with microglial cell activation, we observed profound changes in microbiota, resulting in a more pathogenic microglial phenotype. Interestingly, removal of mice from HFD completely abrogated microglial cell activation and proliferation and changes in gut. Based on these findings, we conclude that inflammation induced by HFD induces profound pathogenic changes in the gut concomitant with pathogenic changes in the CNS leading to neurodegeneration.

Non-alcoholic fatty liver disease induces signs of Alzheimer's disease (AD) in wild-type mice and accelerates pathological signs of AD in an AD model.

BackgroundNon-alcoholic fatty liver disease (NAFLD) is a chronic liver disease afflicting about one third of the world’s population and 30 % of the US population. It is induced by consumption of high-lipid diets and is characterized by liver inflammation and subsequent liver pathology. Obesity and consumption of a high-fat diet are known to increase the risk of Alzheimer’s disease (AD). Here, we investigated NAFLD-induced liver inflammation in the pathogenesis of AD.MethodsWT and APP-Tg mice were fed with a standard diet (SD) or a high-fat diet (HFD) for 2, 5 months, or 1 year to induce NAFLD. Another set of APP-Tg mice were removed from HFD after 2 months and put back on SD for 3 months.ResultsDuring acute phase NAFLD, WT and APP-Tg mice developed significant liver inflammation and pathology that coincided with increased numbers of activated microglial cells in the brain, increased inflammatory cytokine profile, and increased expression of toll-like receptors. Chronic NAFLD induced advanced pathological signs of AD in both WT and APP-Tg mice, and also induced neuronal apoptosis. We observed decreased brain expression of low-density lipoprotein receptor-related protein-1 (LRP-1) which is involved in β-amyloid clearance, in both WT and APP-Tg mice after ongoing administration of the HFD. LRP-1 expression correlated with advanced signs of AD over the course of chronic NAFLD. Removal of mice from HFD during acute NAFLD reversed liver pathology, decreased signs of activated microglial cells and neuro-inflammation, and decreased β-amyloid plaque load.ConclusionsOur findings indicate that chronic inflammation induced outside the brain is sufficient to induce neurodegeneration in the absence of genetic predisposition.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-015-0467-5) contains supplementary material, which is available to authorized users.

Abstract 2791: Just how noisy is xenograft data? Using growth rate modeling and bootstrapping to optimize xenograft study design.

Abstract The evaluation of tumor growth inhibition in xenograft models, generated by subcutaneous implantation of human cancer cell lines, is an integral component of the drug discovery and development process. While xenograft data is ubiquitous, and opinions on its utility are just as common, systematic examinations of signal-to-noise ratio, overall precision of xenograft data and the best metric to report tumor growth inhibition are, remarkably, absent from the literature. To this end, we present a thorough retrospective analysis of xenograft studies from a large in-house database of 225 human xenograft efficacy studies performed from 2006 to present, using a wide range of anti-neoplastic drugs. Individual xenograft tumor growth curves were fit to an exponential model, and a novel measure for data analysis was developed (the model-fitted T/C ratio on Day 21). This novel measure possesses several advantages over a traditional (raw) T/C ratio, notably the use of all available data (not just Day 21), the absence of bias due to informative right-censoring (nonrandom removal of mice in the control group whose tumor volume reached a pre-defined humane endpoint), and the absence of bias due to the inherent slowing of growth kinetics in the control group. The model-fitted T/C ratio on Day 21 was then compared to the raw T/C ratio. For each pair of comparisons between treatment group and control, bootstrapping was used to determine the mean (μ) and standard deviation (σ) of the T/C ratio (either model-fitted or raw). A Z-score measure, (1-μ)/σ, was computed as a measure of the signal-to-noise ratio of the xenograft studies, for 1167 comparisons. For xenograft studies conducted with 10 mice per group over 21 days, the model-fitted T/C ratio outperformed the raw T/C ratio in terms of median Z-score (7.1 and 5.4 respectively). When the number of mice in each group was reduced to 6, and the study length was decreased from 21 to 14 days, a high Z-score (5.1) was still achieved for the model-fitted T/C ratio. The power of xenograft study comparisons for T/C in the range of 0.35 to 0.45 was examined and found to be 0.95 for studies with 6 animals per group using the model-fitted T/C measure. Finally, the misclassification frequency (fraction of comparisons where the treatment was misclassified using a binary cutoff of efficacious vs. non-efficacious) was calculated, and found to be 0.04 using the model-fitted T/C. Our calculations demonstrate that switching to a model-fitted T/C makes more efficient use of the data, yielding considerable cost savings while maintaining a high power and low misclassification rate. The exact degree of benefit from this novel measure and alternative design may vary for other animal facilities, since the noise levels could vary. However, the methods developed here to evaluate potential designs should still be widely applicable, and represent a general approach for the optimization of xenograft studies. Citation Format: Jill Donelan, Greg Hather, Ray Liu, Syamala Bandi, Wen Chyi Shyu, Mark Manfredi, Arijit Chakravarty. Just how noisy is xenograft data? Using growth rate modeling and bootstrapping to optimize xenograft study design. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2791. doi:10.1158/1538-7445.AM2013-2791

In utero and postnatal exposure to arsenic alters pulmonary structure and function

In addition to cancer endpoints, arsenic exposures can also lead to non-cancerous chronic lung disease. Exposures during sensitive developmental time points can contribute to the adult disease. Using a mouse model, in utero and early postnatal exposures to arsenic (100 ppb or less in drinking water) were found to alter airway reactivity to methacholine challenge in 28 day old pups. Removal of mice from arsenic exposure 28 days after birth did not reverse the alterations in sensitivity to methacholine. In addition, adult mice exposed to similar levels of arsenic in drinking water did not show alterations. Therefore, alterations in airway reactivity were irreversible and specific to exposures during lung development. These functional changes correlated with protein and gene expression changes as well as morphological structural changes around the airways. Arsenic increased the whole lung levels of smooth muscle actin in a dose dependent manner. The level of smooth muscle mass around airways was increased with arsenic exposure, especially around airways smaller than 100 μm in diameter. This increase in smooth muscle was associated with alterations in extracellular matrix (collagen, elastin) expression. This model system demonstrates that in utero and postnatal exposure to environmentally relevant levels of arsenic can irreversibly alter pulmonary structure and function in the adults.

Experimental Removal of Strong and Weak Predators: Mice and Chipmunks Preying on Songbird Nests

We examined the effects of separate removal experiments of two generalist consumers, the white-footed mouse (Peromyscus leucopus) and the eastern chipmunk (Tamias striatus), on nest predation rates of forest songbirds. Mice are numerically dominant at our study sites and were shown to be strong predators in other predator–prey interactions, such as those involving gypsy moths. Therefore, we hypothesized that removal of mice would result in decreased levels of nest predation relative to control treatments with a complete predator assemblage, but that the removal of chipmunks would not result in decreased nest predation. Both hypotheses were supported. Mice depredated >60% of artificial nests in control plots (mouse populations intact), whereas chipmunks depredated ∼20%. Daily nest mortality rates in mouse removal treatments were less than half the rates in controls but were virtually identical between chipmunk removal and control treatments. Nonetheless, when we examined predation rates across plots in which the density of mice varied naturally, total daily mortality rates declined as the density of mice increased. This pattern occurred because mortality from non-mouse predators decreased as the density of mice increased and overwhelmed increasing mortality from mice to drive the overall dynamics of the system. Analysis of the relationships between the density of mice and predation rates by mice as a function of the abundance of natural food in their environment revealed probable reasons for these conflicting results. We suggest that high local densities of mice deplete resources for larger, non-mouse predators, which preferentially occupy areas of few mice and high local food abundance. In these areas, songbirds may be faced with higher overall nest predation dominated by non-mouse predators. Mice thus influence nest predation rates through both direct and indirect pathways.

EXPERIMENTAL REMOVAL OF STRONG AND WEAK PREDATORS: MICE AND CHIPMUNKS PREYING ON SONGBIRD NESTS

We examined the effects of separate removal experiments of two generalist consumers, the white-footed mouse (Peromyscus leucopus) and the eastern chipmunk (Tamias striatus), on nest predation rates of forest songbirds. Mice are numerically dominant at our study sites and were shown to be strong predators in other predator–prey interactions, such as those involving gypsy moths. Therefore, we hypothesized that removal of mice would result in decreased levels of nest predation relative to control treatments with a complete predator assemblage, but that the removal of chipmunks would not result in decreased nest predation. Both hypotheses were supported. Mice depredated >60% of artificial nests in control plots (mouse populations intact), whereas chipmunks depredated ∼20%. Daily nest mortality rates in mouse removal treatments were less than half the rates in controls but were virtually identical between chipmunk removal and control treatments. Nonetheless, when we examined predation rates across plots in which the density of mice varied naturally, total daily mortality rates declined as the density of mice increased. This pattern occurred because mortality from non-mouse predators decreased as the density of mice increased and overwhelmed increasing mortality from mice to drive the overall dynamics of the system. Analysis of the relationships between the density of mice and predation rates by mice as a function of the abundance of natural food in their environment revealed probable reasons for these conflicting results. We suggest that high local densities of mice deplete resources for larger, non-mouse predators, which preferentially occupy areas of few mice and high local food abundance. In these areas, songbirds may be faced with higher overall nest predation dominated by non-mouse predators. Mice thus influence nest predation rates through both direct and indirect pathways.

Selective breeding for alcohol withdrawal severity.

Mouse lines have been genetically selected to be alcohol Withdrawal Seizure Prone (WSP) or Resistant (WSR). The selection index is the severity of withdrawal handling-induced convulsions seen after removal of mice from chronic exposure to ethanol vapor. Behavioral, pharmacological, and neurochemical results from a replicated bidirectional selection project are reviewed. In reciprocal F1 crosses of the WSP and WSR lines, substantial dominance for resistance to withdrawal was found in both replicated sets of lines. WSP and WSR mice differ principally, and markedly, in traits related to the severity of withdrawal from alcohols and other drugs with depressant properties. This suggests that genes influencing severity of withdrawal from chronic ethanol exposure also pleiotropically influence genetic susceptibility to dependence on other drugs of abuse. However, the results of WSP vs. WSR comparisons for traits related to ethanol sensitivity and tolerance development suggest control in large part by genes different from those influencing withdrawal severity.

BUOYANT DENSITY ANALYSIS OF MYELOID COLONY‐FORMING CELLS IN GERMFREE AND CONVENTIONAL MICE

Granulocyte-macrophage colony-forming cells (CFUc), in the bone marrow of germfree and conventioal CBA mice, were compared quantitatively and qualitatively. Cells were separated on the basis of their buoyant density by equilibrium centrifugation in continuous albumin density gradients. CFUc in the density subpopulations were detected by culture in agar containing three different types of colony stimulating factor (CSF). The sources of the CSF were post-endotoxin mouse serum (CSFES), mouse lung conditioned medium (CSFMLCM) and human urine (CSFHU). Mice were removed from the germfree environment and the buoyant density status of their CFUc was examined 1, 4 and 8 weeks later. No difference was found between germfree and conventional mice in the number of nucleated cells per femur or in their modal density. Neither was the number of CFUc per femur different. The cell cycle status of CFUc, as determined by the thymidine suicide technique was not significantly different. Functional heterogeneity was found among the density subpopulations for both groups of mice. This depended on the type of CSF. The density distribution of CFUc was significantly different in germfree mice. There were proportionately more low density CFUc. The mean modal density of CFUc under CSFES stimulation was less by 0.0045 g/cm3 in germfree mice. The removal of mice from the germfree environment resulted in a shift of the distribution to higher densities. The trend was towards the conventional situation. The significance of the buoyant density status of CFUc is discussed.

Granulocytopoiesis in germfree mice.

SummaryA comparison of the total number of neutrophils and neutrophil precursors within the humerus of germfree and conventional mice revealed no statistically significant difference between the two groups. The distribution of marrow neutrophils with respect to morphologic type and the number of neutrophils in mitosis were similar in the two groups. There was, however, a slight, but significantly, lower concentration of blood neutrophils in germfree mice as compared to controls. Removal of mice from the germfree environment was associated with a rapid decrease in the number of mature and relatively mature neutrophils in the marrow and with a subsequent increase in potentially mitotic, immature neutrophils, following which the marrow returned to normal. Germfree mice responded to endotoxm administration with an increase in rate of release of neutrophils from the marrow, as do normal mice. It was concluded that in this model system the presence or absence of microorganisms in the environment could not be as...