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Campylobacter diarrhea in an adult mouse model.

An adult mouse (18-20 g) model was developed for studying the pathogenesis of Campylobacter isolates. Iron-loaded BALB/c mice given 10(8)-10(9) Campylobacter colony forming units by intraperitoneal injection developed a severe mucoid diarrhea within 4 h. Severe diarrhea, consisting of unformed stools containing blood, mucus, and fecal leukocytes, persisted for 24 h. Diarrheal symptoms in surviving mice resolved gradually; no diarrhea was observed 5 days after inoculation. Mice not pretreated with iron developed no diarrheal symptoms, and no severe diarrhea was produced in mice inoculated orally. A transient (less than 24 h) bacteremia occurred in mice inoculated either orally or intraperitoneally. Liver, spleen, and kidney were positive for Campylobacter for 48 h; intestinal contents were positive for 5-7 days. Mice given greater than or equal to 10(10) colony forming units showed symptoms of endotoxemia (ruffled fur, inactivity, shaking, tearing, and hypothermia) and died without diarrheal symptoms. Mice given nonpathogenic Escherichia coli strain HB101, heat-killed C. jejuni cells (greater than 10(10)), C. jejuni lipopolysaccharide extract, or purified lipopolysaccharide from either Vibrio cholerae 569B or Salmonella typhimurium showed no diarrheal symptoms.

Animals

Use of a mouse model to examine anti-Helicobacter pylori agents.

A mouse model of Helicobacter infection of the gastric mucosa was evaluated for in vivo screening of new anti-Helicobacter pylori therapies. The aim of the study was to test antimicrobial agents with known anti-H. pylori effects in humans to validate that similar results were obtained in the mouse model. Specific pathogen-free mice were colonized with H. felis, a cat stomach isolate that has been shown to induce chronic gastritis in gnotobiotic mice. In H. felis-inoculated mice 4 weeks after treatment, only 25% were cleared with erythromycin, 47% with metronidazole, 0% with tetracycline, 70% with amoxycillin, and 25% with bismuth subcitrate. In contrast, triple therapy with metronidazole, amoxycillin, and bismuth subcitrate resulted in 80% eradication, whereas triple therapy with metronidazole, tetracycline, and bismuth subcitrate eradicated the Helicobacter from all the animals. We believe the similarities of these treatments to those reported in the literature for humans warrant the use of this model for the early screening of possible anti-H. pylori therapies, especially as in vitro testing has been found to be so non-predictive of therapeutic success.

Animals

Establishment of a mouse model for human rhinovirus infection.

We describe here a mouse model for rhinovirus infection using a variant of human rhinovirus type 2 (HRV2/H) which replicated 50- to 300-fold in the lungs of BALB/c mice. The variant virus differed only marginally from HRV2/H according to various biochemical parameters. Use of a photosensitive inoculum and pretreatment of the animals with actinomycin D were necessary for detection of reproducible and significant levels of virus replication. This mouse model of rhinovirus infection is the first example of human rhinovirus replication in a non-primate mammal, and provides an important link for the development of rhinovirus therapy or prophylaxis.

Animals

Investigating the genomic landscape of mouse models of breast cancer metastasis.

Metastasis remains a major cause of cancer mortality. AbstractThis study, expanding upon previous findings in the MMTV-PyMT model, investigated four independent mouse models, representing luminal (MMTV-PyMT, MMTV-Myc), HER2-amplified (MMTV-Her2) and triple negative (C3(1)TAg) breast cancer subtypes. Consistent with previous results, limited evidence for metastasis-associated somatic point mutations was found for all models. We also found that oncogenic drivers significantly influenced the number and size of metastasis-specific copy number variations (MSCNVs), but common driver-independent MSCNVs were rare. Furthermore, analyzing a cohort with varying genetic backgrounds while maintaining a constant oncogenic driver (PyMT) revealed that genetic background profoundly impacts MSCNVs. Transcriptome analysis demonstrated that oncogenic drivers strongly shaped metastasis-specific gene expression (MSGE), with each driver exhibiting distinct expression profiles. In contrast, MSGE in the PyMT-F1 cohort was more variable across strains. Despite the diversity of MSCNV and MSGE, functional analysis revealed that both mechanisms converge on the modulation of key cellular processes, including immune responses, metabolism, and extracellular matrix interactions. These findings emphasize the complex interplay between oncogenic drivers and genetic background in shaping the genomic and transcriptional landscapes of metastatic lesions.

Journal Article

The hypoxic mouse model for screening cerebral protective agents: a re-examination.

The hypoxic mouse model, in which mice are subjected to an atmosphere of 5% O2 in nitrogen, has been used to screen anesthetics for possible cerebral protection by measuring their ability to prolong survival in mice exposed to hypoxia. Although prolonged survival time in this model is primarily due to a decreased cerebral metabolic rate produced by a specific anesthetic, results can also be influenced by body temperature, dose of anesthetic, and ventilatory or circulatory depression produced by the anesthetic. Using the hypoxic mouse model, the effects of thiopental in conjunction with changes in ambient temperature, changes in thiopental dose, and the presence or absence of nitrous oxide (N2O) were examined. Survival times were measured in eight groups of animals, either untreated animals or animals pretreated with 100 mg/kg thiopental intraperitoneally; exposed to hypoxia in the presence or absence of N2O; at ambient temperatures of either 25 degrees C or 35.5 degrees C. Survival times of seven additional groups of mice, either untreated or treated with doses of 50, 60, 70, 80, 90 or 120 mg/kg thiopental intraperitoneally, exposed to hypoxia in an ambient temperature of 35.5 degrees C were measured to determine a dose-response curve. At an ambient temperature of 35.5 degrees C in which the rectal temperature of both untreated and thiopental-treated animals was maintained near 36 degrees C, thiopental-treated animals did not survive any longer than the untreated animals. Exposure to N2O shortened survival times of both groups by approximately 20%.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthetics

Studies on the genetic and cellular control of sensitivity to enterotoxins in the sealed adult mouse model.

A sealed adult mouse (SAM) model was developed for studies on the effects of cholera enterotoxin (CT). With this system, 38 strains of outbred, inbred, congenic, recombinant, and mutant mice were starved for 24 h, anorectally occluded with cyanoacrylamide ester glue, given CT per os, and sacrificed at 6 h. Fluid accumulation (FA) values were calculated as gut weight to body weight ratios. At a saturating dose of CT (24 micrograms per mouse), FA responses were found to be independent of body weight and gut length. It was found, using recombinant and congenic mice, that mice which possess the H-2k haplotype (homozygous or heterozygous) are 2.5 to 3 times less responsive to CT than animals with the H-2b haplotype. The allele(s) responsible for this affect is located near the K end of the H-2 complex. Inbred and congenic mice given CT intravenously exhibited the same (b = responder, k = nonresponder) pattern in terms of weight loss and death, thus indicating that the H-2 effect is not limited just to the small intestinal epithelium. Mice given sublethal doses of CT intravenously and challenged after conversion to SAM 14 days later showed an immune response inversely related to weight loss (i.e., b haplotypes lost 10 to 15% body weight, recovered, but were not protected against challenge; k haplotypes lost little or no weight but were protected). To examine the possibility of a cellular basis for control of innate responses to CT, responder C57BL/10 (B10) mice were irradiated with 950 rads and immediately reconstituted with bone marrow from (B10 X B10.BR)F1 (nonresponder) mice. The chimeras became nonresponsive to CT when challenged 5 weeks after reconstitution. Reconstituted B10 controls responded normally. Outbred and inbred nude athymic mice also were nonresponsive when compared with normal responder controls. These data demonstrate a genetic basis for resistance to CT and that response and nonresponse is mediated, at least in part, by cells derived from bone marrow.

Animals

A mouse model of focal cerebral ischemia for screening neuroprotective drug effects.

The aim of the present study was to investigate if the infarct area on the brain surface after middle cerebral artery (MCA) occlusion in the mouse is representative for the infarct volume and if this determination of brain injury can be used for screening neuroprotective drug effects. Cerebral infarction was induced by coagulating electrically the stem of the left MCA. After 48 hr, the brains were perfused with carbon black and the unstained infarct area was determined by means of an image analyzing system. The infarct volume was determined by calculating the infarct area on coronal slices and the distance between succeeding slices. The correlation between the area and the volume of infarction was significant (r = 0.81; p less than 0.001). N-methyl-D-aspartate (NMDA) antagonists, calcium antagonists, 5-hydroxytryptamine-1A (5-HT-1A) agonists, radical scavengers, and various drugs were investigated in the mouse model of MCA occlusion. Drugs were usually applicated before ischemia. The drugs that were found to be neuroprotective in the mouse model revealed similar effects in rat models of focal or global cerebral ischemia. These findings show that the presented mouse model with its simple technique of measuring the infarct size is suitable for screening purposes.

Animals

Transgenic mouse models and peptide producing endocrine tumours: morpho-functional aspects.

Three transgenic mouse models which proved to develop endocrine tumours are reviewed and discussed. The neoplasms were induced through the production of the transforming oncoprotein simian virus 40 (SV40) large T-antigen. The SV40/metallothionein-growth hormone (MGH), the insulin/SV40 (INS/SV40) and the vasopressin/SV40 (AVP/SV40) transgenic mice models all developed endocrine tumours of pancreas mainly composed of insulin-producing B cells, with a minor PP cell component. In the pancreata of INS/SV40 and AVP/SV40 transgenic mice, non-tumour lesions (hyperplasia and dysplasia) were also described. AVP/SV40 transgenic mice presented tumour genesis in anterior pituitary too. The usefulness of transgenic mouse models in reproducing human pathology is outlined with special reference to genetically dependent tumours.

Animals

Age of onset, pattern of distribution, and histology of aneurysm development in a genetically predisposed mouse model.

The blotchy mouse has an X chromosome mutation affecting crosslinking of collagen and elastin, which results in aneurysmal dilatation of the aorta. The age of onset, patterns of distribution, and histologic features of these lesions have not been characterized in detail in previous studies. Male normal and blotchy mice 1 to 8 months of age were killed and latex was injected into the left ventricles to facilitate exposure, examination, histologic sampling, and photography of the aorta. Aneurysms were not detected in any normal animals but the affected animals had a progressive increase in the incidence of aneurysms with age, reaching 100% by 6 months. Most aneurysms occurred in the ascending aorta, with some also present in the descending thoracic and abdominal segments. Some animals had multiple aneurysms. Histologically the blotchy mice aortas exhibited disrupted elastic lamellae and thickening of the interlamellar spaces. These spaces contained conspicuously pleomorphic smooth muscle cells, confirmed by electron microscopy. These changes occurred as early as 21 days, when there was no gross evidence of aneurysmal development. Aortic aneurysms develop in blotchy mice in a consistent fashion, with characteristic gross and histologic changes. These animals provide a practical model for further studies of aneurysmal disease, including possible therapeutic interventions to prevent aneurysm development.

Age Factors

Inoculated mouse model of Pneumocystis carinii infection.

A transtracheally inoculated mouse model of Pneumocystis carinii has been developed using BALB/c mice. The advantage of this strain of mice include that they are widely available, inexpensive, and were not infected with Pneumocystis before inoculation. Inoculated mice that were not treated had a mean infectivity score of 4.1 compared with inoculated mice treated with the effective anti-Pneumocystis drug combination of trimethoprim plus sulfamethoxazole, which had a mean infectivity score of 0.1, an approximately 4 log difference. The inoculated BALB/c mouse provides a model to serve as a valuable addition to rat models currently used, providing a source of organisms from a different host for cross-species comparisons and for studies of drug efficacy for therapy and prophylaxis. The inoculated mouse is especially cost effective and allows testing of compounds in short supply.

Aminoquinolines

Inhaled xenon modulates microglia and ameliorates disease in mouse models of amyloidosis and tauopathy.

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder. Antiamyloid antibody treatments modestly slow disease progression in mild dementia due to AD. Emerging evidence shows that homeostatic dysregulation of the brain immune system, especially that orchestrated by microglia, plays an important role in disease onset and progression. Thus, a major question is how to modulate the phenotype and function of microglia to treat AD. Xenon (Xe) gas is a noble gas used in human patients as an anesthetic and a neuroprotectant used for treating brain injuries. Xe penetrates the blood-brain barrier, which could make it an effective therapeutic. To assess the effect of Xe on microglia and AD pathology, we designed a custom Xe inhalation chamber and treated several mouse models of AD with Xe gas. Xe treatment induced mouse microglia to adopt an intermediate activation state that we have termed pre-neurodegenerative microglia (pre-MGnD). This microglial phenotypic transition was observed in mouse models of acute neurodegeneration and amyloidosis (APP/PS1 and 5xFAD mice) and tauopathy (P301S mice). This microglial state enhanced amyloid plaque compaction and reduced dystrophic neurites in the APP/PS1 and 5xFAD mouse models. Moreover, Xe inhalation reduced brain atrophy and neuroinflammation and improved nest-building behavior in P301S mice. Mechanistically, Xe inhalation induced homeostatic brain microglia toward a pre-MGnD state through IFN-γ signaling that maintained the microglial phagocytic response in APP/PS1 and 5xFAD mice while suppressing the microglial proinflammatory phenotype in P301S mice. These results support the translation of Xe inhalation as an approach for treating AD.

Animals

A neonatal mouse model of meningococcal disease.

Neisseria meningitidis, the meningococcus, remains a major cause of bacterial meningitis. Previously developed animal models for this infection do not adequately mimic its natural pathogenesis in humans. We have investigated a number of different potential animal models and describe a neonatal mouse model. Meningococci were instilled intranasally into five-day-old mice; invasiveness was measured by blood cultures and cisternal puncture, and colonization was determined by nasal cultures. Fifty two percent of mice became bacteremic after instillation of strains which are virulent for humans. Human carrier strains were avirulent in this model. Iron dextran enhanced the nasal colonization, invasiveness and mortality due to disease-associated isolates but had no effect on carrier strains. Colonization rates were similar for all strains. There was a marked age-related change in susceptibility to infection which was inversely correlated with levels of serums C3. Immunization of Swiss CD1 dams with N. meningitidis serotype 2 vaccine protected their litters from meningococcal infection. Protective levels of serum antibody were acquired by neonatal mice after suckling immunized dams. The neonatal mouse meets most of the criteria for an appropriate animal model for meningococcemia.

Aging

Intrahepatic Exhausted Antiviral Immunity in an Immunocompetent Mouse Model of Chronic Hepatitis B.

BACKGROUND & AIMS: Targeting exhausted immune systems would be a promising therapeutic strategy to achieve a functional cure for HBV infection in patients with chronic hepatitis B (CHB). However, animal models recapitulating the immunokinetics of CHB are very limited. We aimed to develop an immunocompetent mouse model of CHB for intrahepatic immune profiling. METHODS: CHB mice were created by intrahepatic delivery of the Sleeping Beauty transposon vector tandemly expressing the hepatitis B virus (HBV) genome and fumarylacetoacetate hydrolase (FAH) cDNA into C57BL/6J congenic FAH knockout mice via hydrodynamic tail vein injection. We profiled the viral and intrahepatic immune kinetics in CHB mice with or without treatment with recombinant IFNα or the hepatotropic Toll-like receptor 7 agonist SA-5 using single-cell RNA-seq. RESULTS: CHB mice exhibited sustained HBV viremia and persistent hepatitis. They showed intrahepatic expansion of exhausted CD8+ T (Tex) cells, the frequency of which was positively associated with viral load. Recruited macrophages increased in number but impaired inflammatory responses in the liver. The cytotoxicity of mature natural killer (NK) cells also increased in CHB mice. IFNα and SA-5 treatment both resulted in viral suppression with mild hepatic flares in CHB mice. Although both treatments activated NK cells, SA-5 had the capacity to revitalize the impaired function of Tex cells and liver-recruited macrophages. CONCLUSIONS: Our novel CHB mouse model recapitulated the intrahepatic exhausted antiviral immunity in patients with CHB, which might be able to be reinvigorated by a hepatotropic TLR7 agonist.

Animals

A novel mouse model recapitulates the effects of rs2254524 variant in the lanosterol synthase gene on salt sensitivity and organ damage.

OBJECTIVE: The blood pressure (BP) response to salt intake (salt sensitivity) shows great variability among individuals and is more frequent in hypertensive patients. Elevated levels of the steroid hormone Endogenous Ouabain (EO) are associated with hypertension (HT) and salt sensitivity. The lanosterol synthase gene ( LSS ) plays a key role in the biosynthesis of steroids and its rs2254524 variant (Val642Leu) is linked to salt sensitivity in humans. This study aims to investigate the pathophysiological significance of the Lss missense variation in a new knock-in mouse model of salt-sensitive HT onset. METHODS: We generated a mouse model carrying the murine homolog (Val643Leu) of the human LSS variant. C57BL/6N LssV643L/V643L mice were fed different NaCl diets (low-salt, LSD; normal-salt, NSD; high-salt, HSD) and were characterized at functional, histological, and molecular levels. RESULTS: At baseline, mutant mice showed an enlarged kidney compared to the wild-type (WT) counterpart, but the Lss V643L variant did not affect EO biosynthesis nor systolic BP at 3 and 12 months. In HSD, we observed an increased systolic BP only in 12-month-old LssV643L/V643L mice, compared to NSD. Moreover, only the HSD LssV643L/V643L mice showed cardiac hypertrophy and a higher incidence of cardiac fibrosis compared to WT at 12 months. Finally, the Lss mRNA level was differentially regulated by HSD in the adrenal gland, liver, and heart of LssV643L/V643L mice compared to WT. CONCLUSIONS: The novel Lss mouse model resembles the salt-sensitive HT phenotype observed in hypertensive patients and provides a good model of salt-sensitive HT and HT-mediated organ damage.

Animals

Indirect mouse model for the evaluation of potential antiviral compounds: results with Venezuelan equine encephalomyelitis virus.

An indirect mouse model was utilized to evaluate the antiviral activity of several compounds against Venezuelan equine encephalomyelitis (VEE) virus infection in mice. Mice were given various dosages of lysine-stabilized polyriboinosinic acid-polyribocytidylic acid, a tilorone analogue, kethoxal, or mepacrine before and/or shortly after receiving one of several dose levels of attenuated strain TC-83 VEE virus. Twenty-one days later, the same mice were rechallenged intracranially with virulent Trinidad donkey strain VEE virus. Susceptibility to rechallenge was interpreted as evidence of drug effectiveness in completely preventing the initial immunizing virus infection. In contrast, if a drug lacked antiviral effectiveness, the initial attenuated infection stimulated sufficient immunity to protect mice against the virulent rechallenge. Both of the interferon inducers, lysine-stabilized polyriboinosinic acid-polyribocytidylic acid and tilorone analogue 11,567, possessed significant (P < 0.01) antiviral activity based upon this indirect model, whereas mepacrine and kethoxal were inactive. Results using the indirect method were confirmed by using the conventional direct method for evaluating the effectiveness of potentially useful antiviral compounds. The indirect mouse model described should prove useful for studying drug efficacy against certain viruses that are lethal only by intracranial inoculation.

Animals

Echinococcus granulosus: development of an intermediate host mouse model for use in vaccination studies.

A mouse model has been developed to evaluate potential protective antigens which could render intermediate hosts resistant to a challenge infection with Echinococcus granulosus eggs. DBA/2J, CBA/J, Balb/cJ, C57/B16J and CF-1 mice were initially infected orally and parenterally with eggs, hatched eggs or activated oncospheres. Generally less than 1% of the oral dose established as cysts. Mean cysts counts were increased when Balb/cJ mice were injected intraperitoneally or intravenously with activated oncospheres. A challenge regime using 600 activated oncospheres injected intraperitoneally into adult Balb/cJ mice was subsequently adopted yielding means of 15-51 cysts per mouse. When activated oncospheres were injected intraperitoneally into Balb/cJ, DBA/2J and CF-1 mice, cysts were restricted to the peritoneal cavity. Activated oncospheres injected intravenously, however, lodged almost exclusively in the lung and thoracic cavity, except in DBA/2J mice where 55% lodged in the liver. This anatomical localization enabled the outcome of prior infection and challenge to be monitored separately. Prior infection rendered Balb/cJ mice fully resistant to subsequent challenge.

Animals

Retinal Proteome Profiling of Inherited Retinal Degeneration Across Three Different Mouse Models Suggests Common Drug Targets in Retinitis Pigmentosa.

Inherited retinal degenerations (IRDs) are a leading cause of blindness among the population of young people in the developed world. Approximately half of IRDs initially manifest as gradual loss of night vision and visual fields, characteristic of retinitis pigmentosa (RP). Due to challenges in genetic testing, and the large heterogeneity of mutations underlying RP, targeted gene therapies are an impractical largescale solution in the foreseeable future. For this reason, identifying key pathophysiological pathways in IRDs that could be targets for mutation-agnostic and disease-modifying therapies (DMTs) is warranted. In this study, we investigated the retinal proteome of three distinct IRD mouse models, in comparison to sex- and age-matched wild-type mice. Specifically, we used the Pde6&#x3b2;Rd10 (rd10) and RhoP23H/WT (P23H) mouse models of autosomal recessive and autosomal dominant RP, respectively, as well as the Rpe65-/- mouse model of Leber's congenital amaurosis type 2 (LCA2). The mice were housed at two distinct institutions and analyzed using LC-MS in three separate facilities/instruments following data-dependent and data-independent acquisition modes. This cross-institutional and multi-methodological approach signifies the reliability and reproducibility of the results. The large-scale profiling of the retinal proteome, coupled with in&#xa0;vivo electroretinography recordings, provided us with a reliable basis for comparing the disease phenotypes and severity. Despite evident inflammation, cellular stress, and downscaled phototransduction observed consistently across all three models, the underlying pathologies of RP and LCA2 displayed many differences, sharing only four general KEGG pathways. The opposite is true for the two RP models in which we identify remarkable convergence in proteomic phenotype even though the mechanism of primary rod death in rd10 and P23H mice is different. Our data highlights the cAMP and cGMP second-messenger signaling pathways as potential targets for therapeutic intervention. The proteomic data is curated and made publicly available, facilitating the discovery of universal therapeutic targets for RP.

Animals

Production of toxic shock syndrome toxin 1 in a mouse model of Staphylococcus aureus abscess formation.

A mouse model of abscess formation is described in which toxic shock syndrome toxin 1 (TSST-1) is produced by Staphylococcus aureus in vivo. Mice injected intravenously with S. aureus developed renal abscesses within 4-7 days. Kidneys excised from infected mice were cultured quantitatively, and extracts from the kidneys were assayed for TSST-1 with use of a competitive enzyme-linked immunosorbent assay. Animals with less than 10(7) S. aureus/g of kidney had less than 6 ng of TSST-1/mL of extract. Toxin levels ranged from less than 6 ng/mL to 271 ng/mL in kidney extracts from mice with greater than 10(7) S. aureus/g of kidney. Urine from infected mice also contained measurable levels of TSST-1 (range, less than 6-728 ng/mL). Mice developed serum antibodies to TSST-1 by 2 weeks after challenge. Serum samples collected 5-7 days after bacterial challenge did not show biochemical changes typical of a toxic shock-like illness in these animals.

Abscess