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At least 1,729 records · Page 96Linked to original sources
PubMed2005

Use of a transgenic mouse model to identify markers of human lung tumors.

Lung cancer remains the leading cause of cancer related deaths worldwide. Despite advances in detection technologies, most patients diagnosed with lung cancer already harbor metastatic lesions. Because early detection is one of the primary determinants of patient outcome, a transgenic mouse model of lung cancer was utilized to identify markers of early lung tumors in humans. DNA microarray analysis of lung tumors arising in MMTV-IGF-II transgenic mice showed 9 genes consistently elevated in the murine lung tumors. Western blot analyses confirmed that several of these proteins were elevated in the lung tumors and immunohistochemical analyses identified 3 proteins, microsomal glutathione-S-transferase 1 (Mgst1), cathepsin H and syndecan 1 as being consistently elevated in the murine lung tumors compared to non-tumor bearing transgenic lung tissue and normal lung tissue surrounding the tumor. These 3 proteins were also elevated in human lung adenocarcinoma and squamous cell carcinomas. Importantly, the proteins were elevated in early stage, node negative tumors indicating their ability to detect early lung lesions that would be amenable to surgical resection. Therefore, our findings indicate that Mgst1, cathepsin H and syndecan 1 should be further evaluated as markers capable of identifying patients with early stage lung tumors.

Animals↗
PubMed2000

Limited role of polymorphonuclear neutrophils in a pregnant mouse model of secondary infection by Chlamydophila abortus (Chlamydia psittaci serotype 1).

The aim of this work was to study the role of polymorphonuclear neutrophils (PMNs) in the clearance of infection, and in the development of specific immunity against Chlamydophila abortus (Chlamydia psittaci serotype 1) secondary infection. A pregnant mouse model depleted of neutrophils by the RB6-8C5 monoclonal antibody was used. No clinical signs were observed in depleted or non-depleted mice after secondary infection and no significant differences were observed in the litter size between the infected and control groups. In PMN-depleted mice C. abortus was not detected in the materno-fetal unit but merely produced low, persistent levels of infection in spleen and liver. In the non-depleted mice the level of infection was significantly lower, being resolved during the first few days post-reinfection. In both infected mice groups the immune response in the liver was quickly established and was seen to be composed mainly of CD4(+)T lymphocytes and macrophages. A Th1 response characterized by the presence of IFN-gamma and TNF-alpha in serum was observed during early infection, with significantly higher levels in the non-depleted animals. Our results suggest that PMNs have little influence on the control of C. abortus secondary infection, although they are a first line of defense and may influence the early production of TNF-alpha and IFN-gamma.

Animals↗
PubMed2005

The HMG-CoA reductase inhibitor lovastatin reverses the learning and attention deficits in a mouse model of neurofibromatosis type 1.

Neurofibromatosis Type 1 (NF1) is a common neurological disorder caused by mutations in the gene encoding Neurofibromin, a p21Ras GTPase Activating Protein (GAP). Importantly, NF1 causes learning disabilities and attention deficits. A previous study showed that the learning and memory deficits of a mouse model of NF1 (nf1+/-) appear to be caused by excessive p21Ras activity leading to impairments in long-term potentiation (LTP), a cellular mechanism of learning and memory. Here, we identify lovastatin as a potent inhibitor of p21Ras/Mitogen Activated Protein Kinase (MAPK) activity in the brain. Lovastatin is a specific inhibitor of three-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, used commonly for the treatment of hypercholesterolemia. We report that lovastatin decreased the enhanced brain p21Ras-MAPK activity of the nf1+/- mice, rescued their LTP deficits, and reversed their spatial learning and attention impairments. Therefore, these results demonstrate that lovastatin may prove useful in the treatment of Neurofibromatosis Type 1.

Analysis of Variance↗
PubMed2002

Pathways to motor neuron degeneration in transgenic mouse models.

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurological disorder characterized by the selective loss of motor neurons. A pathological hallmark of both sporadic and familial ALS is the presence of abnormal accumulations of neurofilament and peripherin proteins in motor neurons. In the past decade, transgenic mouse approaches have been used to address the role of such cytoskeletal abnormalities in motor neuron disease and also to unravel the pathogenesis caused by mutations in the gene coding for superoxide dismutase 1 (SOD1) that account for ~20% of familial ALS cases. In mouse models, disparate effects could result from different types of intermediate filament (IF) aggregates. Perikaryal IF accumulations induced by the overexpression of any of the three wild-type neurofilament proteins were quite well tolerated by motor neurons. Indeed, perikaryal swellings provoked by NF-H overexpression can even confer protection against toxicity of mutant SOD1. Other types of IF aggregates seem neurotoxic, such as those found in transgenic mice overexpressing either peripherin or an assembly-disrupting NF-L mutant. Moreover, understanding the toxicity of SOD1 mutations has been surprisingly difficult. The analysis of transgenic mice expressing mutant SOD1 has yielded complex results, suggesting that multiple pathways may contribute to disease that include the involvement of non-neuronal cells.

Adult↗
PubMed2002

Elucidation of estrogen receptor function in bone with the use of mouse models.

Since the discovery that estrogen receptors (ERs) are present in bone cells, there has been intense research into the action of estrogen in bone. During the past decade, humans with disturbed estrogen signaling, either as a result of ER alpha or aromatase deficiency, have been reported. Furthermore, mouse models have been established with a deficiency of ER alpha, ER beta or both, in addition to deficiency of aromatase. This review focuses on data accumulated during the past three years from studies of knockout mice with impaired estrogen signaling resulting from ER or aromatase deficiency.

Animals↗
PubMed2006

Selective effects of citalopram in a mouse model of stress-induced anhedonia with a control for chronic stress.

A stress-induced decrease in sucrose preference in rodents is regarded as an analog of anhedonia, a key symptom of depression. We investigated the effects of citalopram, administrated via drinking water (15 mg/kg/day), in a mouse model of stress-induced anhedonia. In this model, chronic stress induces anhedonia in a subset of C57BL/6N mice, while the remaining animals do not show a hedonic deficit or other depressive-like behaviors, although they are exposed to the same stressors as the anhedonic mice. Pre-stress and post-stress treatment with citalopram counteracted the development and maintenance of anhedonia and rescued normal floating in the forced swim test, demonstrating an antidepressant-like action. During the post-stress treatment, citalopram selectively increased sucrose preference and intake on the fourth week of treatment in anhedonic mice without affecting non-anhedonic animals. Citalopram also decreased elevated water consumption in the anhedonic group. Citalopram, administered 1 week before and during a 4-week stress procedure, decreased the percentage of anhedonic mice and reduced the increase of water intake in stressed mice. This study suggests that our chronic stress paradigm can serve as a model of anhedonia, in which antidepressant treatment is selectively effective in animals with a hedonic deficit.

Animals↗
PubMed2006

Limbic neurogenesis/plasticity in the R6/2 mouse model of Huntington's disease.

Huntington's disease is an inherited neurodegenerative condition characterized by movement disorders, and mood and cognitive disturbance. Mammalian neurogenesis persists into adulthood in the subventricular zone and dentate gyrus of the hippocampus. Neurogenesis is abnormal in the dentate gyrus in the R6/2 transgenic mouse model of Huntington's disease. We have now found that the number of immature neurons (doublecortin-positive cells) is markedly reduced in the piriform and insular cortex but not in the temporal germinal layer or caudal subventricular zone of R6/2 mice. Furthermore, numbers of such cells were unaltered in response to seizures in both wild-type and R6/2 mice. These results support the possibility that impaired neurogenesis and/or plasticity could contribute to cognitive and psychiatric impairments in Huntington's disease.

Aging↗
PubMed2000

Effect of antibiotics, levofloxacin and fosfomycin, on a mouse model with Escherichia coli O157 infection.

There have been some reservations about the treatment of enterohemorrhagic Escherichia coli (EHEC) infection with antibiotics to prevent the occurrence of hemolytic uremic syndrome (HUS). However, the administration of antimicrobial agents for EHEC infection is under discussion. Therefore, we used an experimental mouse model to assess the advantage/disadvantage of two major antibiotics, levofloxacin (LVFX) and fosfomycin (FOM). Germ-free IQI mice were inoculated with EHEC O157 strain EDL931 or #7. Bacteria colonized feces at 10(9)-10(10) CFU/g, and Shiga toxins (STXs) were detected in the feces. From 1 day after infection, mice were assigned to LVFX (20 mg/kg) once daily or FOM (400 mg/kg) once daily. A significant decrease in overall mortality was observed after treatment of LVFX, with EHEC disappearing immediately from the feces of mice. FOM also reduced mortality for one strain, the STX level decreased gradually. LVFX exhibited higher therapeutic efficacy than FOM. Strain differences were observed in the model during the treatment.

Animals↗
PubMed2004

The impact of P-glycoprotein on the disposition of drugs targeted for indications of the central nervous system: evaluation using the MDR1A/1B knockout mouse model.

Thirty-two structurally diverse drugs used for the treatment of various conditions of the central nervous system (CNS), along with two active metabolites, and eight non-CNS drugs were measured in brain, plasma, and cerebrospinal fluid in the P-glycoprotein (P-gp) knockout mouse model after subcutaneous administration, and the data were compared with corresponding data obtained in wild-type mice. Total brain-to-plasma (B/P) ratios for the CNS agents ranged from 0.060 to 24. Of the 34 CNS-active agents, only 7 demonstrated B/P area under the plasma concentration curve ratios between P-gp knockout and wild-type mice that did not differ significantly from unity. Most of the remaining drugs demonstrated 1.1- to 2.6-fold greater B/P ratios in P-gp knockout mice versus wild-type mice. Three, risperidone, its active metabolite 9-hydroxyrisperidone, and metoclopramide, showed marked differences in B/P ratios between knockout and wild-type mice (6.6- to 17-fold). Differences in B/P ratios and cerebrospinal fluid/plasma ratios between wild-type and knockout animals were correlated. Through the use of this model, it appears that most CNS-active agents demonstrate at least some P-gp-mediated transport that can affect brain concentrations. However, the impact for the majority of agents is probably minor. The example of risperidone illustrates that even good P-gp substrates can still be clinically useful CNS-active agents. However, for such agents, unbound plasma concentrations may need to be greater than values projected using receptor affinity data to achieve adequate receptor occupancy for effect.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2005

Systemic administration of the chemokine macrophage inflammatory protein 1alpha exacerbates inflammatory bowel disease in a mouse model.

INTRODUCTION: Exacerbations of inflammatory bowel disease are thought to be related to concurrent infections. As infections are associated with elevated local and serum concentrations of chemokines, we have determined whether systemic administration of the CC chemokine macrophage inflammatory protein 1alpha (MIP-1alpha) exacerbates colitis in a mouse model. METHODS: Colitis was induced in Balb/c mice using trinitrobenzene sulfonic acid (TNBS). Starting four days later, animals received daily intraperitoneal injections of recombinant MIP-1alpha. On day 7, mice were killed and pieces of colon taken for immunohistology and polymerase chain reaction analysis. The direct effects of MIP-1alpha on mucosal T cells and fibroblasts in vitro were also investigated. RESULTS: Systemic administration of MIP-1alpha markedly enhanced colitis with mice developing large transmural ulcers filled with granulation tissue. Treatment resulted in increased numbers of CD4 cells infiltrating the colonic lamina propria, increased interferon gamma (IFN-gamma) levels, and increased transcripts for tumour necrosis factor alpha (TNF-alpha) and matrix metalloproteinase 3 (MMP3). Isolated lamina propria lymphocytes from mice with TNBS colitis contained increased numbers of IFN-gamma and TNF-alpha transcripts when stimulated with MIP-1alpha in vitro. Colonic lamina propria fibroblasts also responded to MIP-1alpha with increased proliferation and decreased collagen 1 synthesis but fibroblast proliferation was not seen in vivo. CONCLUSIONS: These experiments show that increasing serum concentrations of a chemokine, MIP-1alpha, exacerbates immune mediated colitis. The effect seems to be due to the ability of MIP-1alpha to boost Th1 responses in the gut wall. Our findings also suggest a potential pathway by which peripheral infections can exacerbate inflammatory bowel disease.

Animals↗
PubMed2005

Knock-in mouse models of Huntington's disease.

Huntington's disease is an autosomal dominant neurodegenerative disorder that is characterized by motor, cognitive, and psychiatric alterations. The mutation responsible for this fatal disease is an abnormally expanded and unstable CAG repeat within the coding region of the gene encoding huntingtin. Numerous mouse models have been generated that constitute invaluable tools to examine the pathogenesis of the disease and to develop and evaluate novel therapies. Among those models, knock-in mice provide a genetically precise reproduction of the human condition. The slow progression and early development of behavioral, pathological, cellular, and molecular abnormalities in knock-in mice make these animals valuable to understand the early pathological events triggered by the mutation. This review describes the different knock-in models generated, the insight gained from them, and their value in the development and testing of prospective treatments of the disease.

Animals↗
PubMed2003

Inhibition of calpains prevents neuronal and behavioral deficits in an MPTP mouse model of Parkinson's disease.

The molecular mechanisms mediating degeneration of midbrain dopamine neurons in Parkinson's disease (PD) are poorly understood. Here, we provide evidence to support a role for the involvement of the calcium-dependent proteases, calpains, in the loss of dopamine neurons in a mouse model of PD. We show that administration of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) evokes an increase in calpain-mediated proteolysis in nigral dopamine neurons in vivo. Inhibition of calpain proteolysis using either a calpain inhibitor (MDL-28170) or adenovirus-mediated overexpression of the endogenous calpain inhibitor protein, calpastatin, significantly attenuated MPTP-induced loss of nigral dopamine neurons. Commensurate with this neuroprotection, MPTP-induced locomotor deficits were abolished, and markers of striatal postsynaptic activity were normalized in calpain inhibitor-treated mice. However, behavioral improvements in MPTP-treated, calpain inhibited mice did not correlate with restored levels of striatal dopamine. These results suggest that protection against nigral neuron degeneration in PD may be sufficient to facilitate normalized locomotor activity without necessitating striatal reinnervation. Immunohistochemical analyses of postmortem midbrain tissues from human PD cases also displayed evidence of increased calpain-related proteolytic activity that was not evident in age-matched control subjects. Taken together, our findings provide a potentially novel correlation between calpain proteolytic activity in an MPTP model of PD and the etiology of neuronal loss in PD in humans.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2005

Recombinant adeno-associated virus 2-mediated antiangiogenic prevention in a mouse model of intraperitoneal ovarian cancer.

PURPOSE: In the present study, we sought to determine the potential of sustained transgene expression by a single i.m. administration of recombinant adeno-associated virus 2 (rAAV) encoding angiostatin and endostatin in inhibiting i.p. ovarian cancer growth and dissemination in a preclinical mouse model. EXPERIMENTAL DESIGN: Cohorts of female athymic nude mice received either no virus or 1.2 x 10(11) particles of rAAV encoding green fluorescence protein or endostatin plus angiostatin, i.m. Three weeks later, the mice were i.p. injected with 10(6) human epithelial ovarian cancer cell line SKOV3.ip1. As a measure of effectiveness of the therapy, tumor weight, abdominal distension, ascites volume and vascular endothelial growth factor level, and tumor weight were determined. Immunohistochemistry was done to determine tumor cell apoptosis and endothelial cell proliferation following the therapy. Tumor-free survival was recorded as the end point. RESULTS: Results indicated a significant tumor-free survival (P < 0.003) following therapy with rAAV encoding endostatin and angiostatin compared with untreated or rAAV-green fluorescence protein-treated mice. Ascites volume in rAAV endostatin and angiostatin-treated mice was significantly lower than naive mice and contained less hemorrhage and tumor conglomerates. The level of vascular endothelial growth factor in the ascites of antiangiogenic vector treated mice was also significantly less compared with the untreated mice. Immunohistochemical analyses indicated increased tumor cell apoptosis and decreased blood vasculature following rAAV endostatin and angiostatin treatment. CONCLUSION: The results indicate that antiangiogenic genetic prevention from stable systemic levels of angiostatin and endostatin by i.m. administration of rAAV can be used for the treatment of i.p. ovarian cancer growth and dissemination.

Angiogenesis Inhibitors↗
PubMed2002

Transgenic and knockout mouse models for the study of luteinizing hormone and luteinizing hormone receptor function.

The main functions of luteinizing hormone (LH) are concerned with regulation of gonadal function, and these functions are today well delineated through previous physiological studies. However, novel information of less well-known aspects of actions of this hormone is currently emerging from studies on genetically modified mouse models, with either enhanced or suppressed LH/LH receptor (LHR) function. The novel functions of LH include its role, in specific situations, as promoter of formation and growth of gonadal and extragonadal tumors. Chronically elevated LH levels in transgenic (TG) mice can also induce responses to this hormone in extragonadal tissues. The knockout (KO) mouse for the LHR has elucidated various less well-known details in the function of LH during ontogeny and adult life. Finally, studies on LHR promoter function have revealed that the expression of this gene occurs in age, sex and tissues-specific fashion. The purpose of this brief review is to summarize some of our recent findings upon studies of TG and KO mice with altered function of LH or its receptor.

Animals↗
PubMedDate not supplied

Oxymetholone: II. Evaluation in the Tg-AC transgenic mouse model for detection of carcinogens.

Several rodent models are under examination as possible alternatives to the classical 2-yr carcinogenicity bioassay. The Tg.AC transgenic mouse has been proposed as a shorter term model offering the possibility of detecting nongenotoxic and genotoxic carcinogenic agents. Retrospective studies of chemicals with established carcinogenic potential have revealed a close correlation between classical bioassay results and the production of skin tumors in the Tg.AC mouse model. Oxymetholone is a synthetic testosterone derivative that is a suspected carcinogen but has shown no evidence of genotoxic activity in a comprehensive battery of genetic toxicity assays. It currently is being tested by the National Toxicology Program (NTP) in a 2-yr rat carcinogenicity bioassay. Because of its nongenotoxicity and the ongoing chronic bioassay, oxymetholone was considered an ideal candidate for a prospective evaluation of the predictive validity of the Tg.AC dermal carcinogenicity model. Consequently, a 6-mo dermal study with oxymetholone in the Tg.AC mouse model was initiated and completed prior to disclosure of the NTP rat bioassay results. In this study, male and female hemizygous Tg.AC mice, 7-8 wk old, were housed individually in suspended plastic cages. An area of dorsal skin was shaved to accommodate dermal applications of 200-microl doses of vehicle control (acetone), drug (1.2, 6.0, or 12 mg oxymetholone in dimethylsulfoxide:acetone, 20:80), or positive control (1.25 microg 12-o-tetradecanoyl-phorbol-13-acetate [TPA]) solutions. Mice received oxymetholone or acetone daily or TPA twice weekly for 20 wk followed by a 6-wk recovery period. The acetone control groups exhibited low spontaneous incidences of papillomas, whereas dermal application of oxymetholone produced dose-related increases in the numbers of papilloma-bearing mice and the numbers of papillomas per animal. Females showed a somewhat greater response to the androgen than did the males. TPA caused an unequivocal increase in papillomas, with males exhibiting a greater response than females. The results of this study indicate that this nongerotoxic androgenic compound possesses proliferative properties. The results predict that chronic systemic administration of oxymetholone will most likely be associated with increased incidences of neoplasms.

Anabolic Agents↗
PubMed2006

Severe endothelial dysfunction in the aorta of a mouse model of Fabry disease; partial prevention by N-butyldeoxynojirimycin treatment.

OBJECTIVE: Fabry disease results from alpha-gala-ctosidase A deficiency and is characterized by the lysosomal accumulation of globotriaosylceramide. Globotriaosylceramide storage predominantly affects endothelial cells, altering vascular wall morphology and vasomotor function. Our objective was to investigate aortic globotriaosylceramide levels, morphology and function in a mouse model of Fabry disease, and the effect of substrate reduction therapy, using the glycosphingolipid biosynthesis inhibitor N-butyldeoxynojirimycin. METHODS AND RESULTS: Mice used were C57BL/6J and alpha-galactosidase A knockout (Fabry). We show progressive accumulation of aortic globotriaosylceramide throughout the lifespan of untreated Fabry mice (55-fold elevation at 2 months increasing to 187-fold by 19 months), localized to endothelial and vascular smooth-muscle cells; there was no effect on vascular wall morphology in young Fabry mice. In old mice, storage resulted in intimal thickening. Endothelial function declined with age in Fabry mouse aorta. Aortae from N-butyldeoxynojirimycin-treated Fabry mice at 19 months of age had reduced endothelial globotriaosylceramide storage, fewer morphological abnormalities and less severe vasomotor dysfunction compared with untreated littermates. CONCLUSION: We provide evidence of a novel vascular phenotype in the Fabry mouse that has relevance to vascular disease in Fabry patients. N-Butyldeoxynojirimycin treatment partially prevented the phenotype in the Fabry mouse by reducing endothelial globotriaosylceramide storage.

1-Deoxynojirimycin↗
PubMed2006

Evidence for abnormal early development in a mouse model of Rett syndrome.

Rett syndrome (RTT) is a neurodevelopmental disorder that affects mainly females, associated in most cases to mutations in the MECP2 gene. After an apparently normal prenatal and perinatal period, patients display an arrest in growth and in psychomotor development, with autistic behaviour, hand stereotypies and mental retardation. Despite this classical description, researchers always questioned whether RTT patients did have subtle manifestations soon after birth. This issue was recently brought to light by several studies using different approaches that revealed abnormalities in the early development of RTT patients. Our hypothesis was that, in the mouse models of RTT as in patients, early neurodevelopment might be abnormal, but in a subtle manner, given the first descriptions of these models as initially normal. To address this issue, we performed a postnatal neurodevelopmental study in the Mecp2(tm1.1Bird) mouse. These animals are born healthy, and overt symptoms start to establish a few weeks later, including features of neurological disorder (tremors, hind limb clasping, weight loss). Different maturational parameters and neurological reflexes were analysed in the pre-weaning period in the Mecp2-mutant mice and compared to wild-type littermate controls. We found subtle but significant sex-dependent differences between mutant and wild-type animals, namely a delay in the acquisition of the surface and postural reflexes, and impaired growth maturation. The mutant animals also show altered negative geotaxis and wire suspension behaviours, which may be early manifestations of later neurological symptoms. In the post-weaning period the juvenile mice presented hypoactivity that was probably the result of motor impairments. The early anomalies identified in this model of RTT mimic the early motor abnormalities reported in the RTT patients, making this a good model for the study of the early disease process.

Animals↗
PubMed2006

Motor unit number estimation predicts disease onset and survival in a transgenic mouse model of amyotrophic lateral sclerosis.

Motor unit number estimation (MUNE) has proved useful in predicting rate of progression and survival in patients with amyotrophic lateral sclerosis (ALS). In animal models, it has demonstrated physiological effects of experimental medications that were not evident behaviorally. We sought to determine more specifically what aspects of function and survival that MUNE could predict in the G93A transgenic mouse model of ALS. Transgenic mice were examined in two distinct treatment studies, neither of which showed an effect of drug on survival, behavioral measures, or MUNE. MUNE was performed using a modification of the incremental stimulation method by stimulating the sciatic nerve at the sciatic notch, and recording with a circumferential surface electrode around the ipsilateral distal hindlimb. Both limbs were studied and the results averaged. MUNE was performed longitudinally on all animals from near onset to premorbid state. Each study was evaluated separately. For both studies, MUNE at initial study correlated significantly with behavioral determination of disease onset, and MUNE slope from initial to final study correlated significantly with disease duration, as measured from onset to time of death. However, the final MUNE value did not correlate with survival. Thus, in two studies involving animals with quite different disease courses, initial MUNE effectively predicted symptom onset and MUNE slope predicted survival. This suggests that MUNE has potential efficacy as a useful functional outcome measure in both animal and human studies of ALS.

Age of Onset↗