| 1. |
- Crivello, M., et al.
(författare)
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Vascular regression precedes motor neuron loss in the FUS (1-359) ALS mouse model
- 2019
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Ingår i: Disease Models and Mechanisms. - : Company of Biologists Ltd. - 1754-8403 .- 1754-8411. ; 12:8
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Tidskriftsartikel (refereegranskat)abstract
- Amyotrophic lateral sclerosis (ALS) presents a poorly understood pathogenesis. Evidence from patients and mutant SOD1 mouse models suggests vascular damage may precede or aggravate motor dysfunction in ALS. We have previously shown angiogenin (ANG) treatment enhances motor neuron survival, delays motor dysfunction and prevents vascular regression in the SOD1G93A ALS model. However, the existence of vascular defects at different stages of disease progression remains to be established in other ALS models. Here, we assessed vascular integrity in vivo throughout different disease stages, and investigated whether ANG treatment reverses vascular regression and prolongs motor neuron survival in the FUS (1-359) mouse model of ALS. Lumbar spinal cord tissue was collected from FUS (1-359) and non-transgenic control mice at postnatal day (P)50, P90 and P120. We found a significant decrease in vascular network density in lumbar spinal cords from FUS (1-359) mice by day 90, at which point motor neuron numbers were unaffected. ANG treatment did not affect survival or counter vascular regression. Endogenous Ang1 and Vegf expression were unchanged at P50 and P90; however, we found a significant decrease in miRNA 126 at P50, indicating vascular integrity in FUS mice may be compromised via an alternative pathway. Our study demonstrates that vascular regression occurs before motor neuron degeneration in FUS (1-359) mice, and highlights that heterogeneity in responses to novel ALS therapeutics can already be detected in preclinical mouse models of ALS.
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| 2. |
- Fernius, Josefin, et al.
(författare)
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Bar-coding neurodegeneration: identifying subcellular effects of human neurodegenerative disease proteins using Drosophila leg neurons
- 2017
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Ingår i: Disease Models and Mechanisms. - : COMPANY OF BIOLOGISTS LTD. - 1754-8403 .- 1754-8411. ; 10:8, s. 1027-1038
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Tidskriftsartikel (refereegranskat)abstract
- Genetic, biochemical and histological studies have identified a number of different proteins as key drivers of human neurodegenerative diseases. Although different proteins are typically involved in different diseases, there is also considerable overlap. Addressing disease protein dysfunction in an in vivo neuronal context is often time consuming and requires labor-intensive analysis of transgenic models. To facilitate the rapid, cellular analysis of disease protein dysfunction, we have developed a fruit fly (Drosophila melanogaster) adult leg neuron assay. We tested the robustness of 41 transgenic fluorescent reporters and identified a number that were readily detected in the legs and could report on different cellular events. To test these reporters, we expressed a number of human proteins involved in neurodegenerative disease, in both their mutated and wild-type versions, to address the effects on reporter expression and localization. We observed strikingly different effects of the different disease proteins upon the various reporters with, for example, A beta(1-42) being highly neurotoxic, tau, parkin and HTT128Q affecting mitochondrial distribution, integrity or both, and A beta(1-42), tau, HTT128Q and ATX1(82Q) affecting the F-actin network. This study provides proof of concept for using the Drosophila adult leg for inexpensive and rapid analysis of cellular effects of neurodegenerative disease proteins in mature neurons.
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| 3. |
- Follwaczny, Philipp, et al.
(författare)
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Pumilio2-deficient mice show a predisposition for epilepsy.
- 2017
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Ingår i: Disease Models and Mechanisms. - : The Company of Biologists. - 1754-8403 .- 1754-8411. ; 10:11, s. 1333-1342
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Tidskriftsartikel (refereegranskat)abstract
- Epilepsy is a neurological disease that is caused by abnormal hypersynchronous activities of neuronal ensembles leading to recurrent and spontaneous seizures in human patients. Enhanced neuronal excitability and a high level of synchrony between neurons seem to trigger these spontaneous seizures. The molecular mechanisms, however, regarding the development of neuronal hyperexcitability and maintenance of epilepsy are still poorly understood. Here, we show that pumilio RNA-binding family member 2 (Pumilio2; Pum2) plays a role in the regulation of excitability in hippocampal neurons of weaned and 5-month-old male mice. Almost complete deficiency of Pum2 in adult Pum2 gene-trap mice (Pum2 GT) causes misregulation of genes involved in neuronal excitability control. Interestingly, this finding is accompanied by the development of spontaneous epileptic seizures in Pum2 GT mice. Furthermore, we detect an age-dependent increase in Scn1a (Nav1.1) and Scn8a (Nav1.6) mRNA levels together with a decrease in Scn2a (Nav1.2) transcript levels in weaned Pum2 GT that is absent in older mice. Moreover, field recordings of CA1 pyramidal neurons show a tendency towards a reduced paired-pulse inhibition after stimulation of the Schaffer-collateral-commissural pathway in Pum2 GT mice, indicating a predisposition to the development of spontaneous seizures at later stages. With the onset of spontaneous seizures at the age of 5 months, we detect increased protein levels of Nav1.1 and Nav1.2 as well as decreased protein levels of Nav1.6 in those mice. In addition, GABA receptor subunit alpha-2 (Gabra2) mRNA levels are increased in weaned and adult mice. Furthermore, we observe an enhanced GABRA2 protein level in the dendritic field of the CA1 subregion in the Pum2 GT hippocampus. We conclude that altered expression levels of known epileptic risk factors such as Nav1.1, Nav1.2, Nav1.6 and GABRA2 result in enhanced seizure susceptibility and manifestation of epilepsy in the hippocampus. Thus, our results argue for a role of Pum2 in epileptogenesis and the maintenance of epilepsy.
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| 4. |
- Gouignard, Nadège, et al.
(författare)
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Musculocontractural Ehlers-Danlos syndrome and neurocristopathies : Dermatan sulfate is required for Xenopus neural crest cells to migrate and adhere to fibronectin
- 2016
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Ingår i: Disease Models and Mechanisms. - : The Company of Biologists. - 1754-8403 .- 1754-8411. ; 9:6, s. 607-620
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Tidskriftsartikel (refereegranskat)abstract
- Of all live births with congenital anomalies, approximately one-third exhibit deformities ofthe head and face. Most craniofacial disorders are associated with defects in a migratory stem and progenitor cell population, which is designated the neural crest (NC). Musculocontractural Ehlers-Danlos syndrome (MCEDS) is a heritable connective tissue disorder with distinct craniofacial features; this syndrome comprises multiple congenital malformations that are caused bydysfunction ofdermatan sulfate (DS) biosynthetic enzymes, including DS epimerase-1 (DS-epi1; also known as DSE). Studies in mice have extended our understanding of DS-epi1 inconnective tissue maintenance; however, its role in fetal development is not understood. We demonstrate that DS-epi1isimportant for the generationofisolated iduronic acid residues in chondroitin sulfate (CS)/DS proteoglycans in early Xenopus embryos. The knockdown of DS-epi1 does not affect the formation of early NC progenitors; however, it impairs the correct activation of transcription factors involved in the epithelial-mesenchymal transition (EMT) and reduces the extent of NC cell migration, which leads to a decrease in NC-derived craniofacial skeleton, melanocytes and dorsal fin structures. Transplantation experiments demonstrate a tissue-autonomous role for DS-epi1 in cranial NC cell migration in vivo. Cranial NC explant and single-cell cultures indicate a requirement of DS-epi1 in cell adhesion, spreading and extension of polarized cell processes on fibronectin. Thus, our work indicates a functional link between DS and NC cell migration. We conclude that NC defects in the EMT and cell migration might account for the craniofacial anomalies and other congenital malformations in MCEDS, which might facilitate the diagnosis and development of therapies for this distressing condition. Moreover, the presented correlations between human DS-epi1 expression and gene sets of mesenchymal character, invasion and metastasis in neuroblastoma and malignant melanoma suggest an association between DS and NC-derived cancers.
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| 5. |
- Guan, Jikui, et al.
(författare)
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The ALK inhibitor PF-06463922 is effective as a single agent in neuroblastoma driven by expression of ALK and MYCN
- 2016
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Ingår i: DMM Disease Models and Mechanisms. - : The Company of Biologists. - 1754-8403 .- 1754-8411. ; 9:9, s. 941-952
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Tidskriftsartikel (refereegranskat)abstract
- The first-in-class inhibitor of ALK, c-MET and ROS1, crizotinib (Xalkori), has shown remarkable clinical efficacy in treatment of ALK-positive non-small cell lung cancer. However, in neuroblastoma, activating mutations in the ALK kinase domain are typically refractory to crizotinib treatment, highlighting the need for more potent inhibitors. The next-generation ALK inhibitor PF-06463922 is predictedto exhibit increased affinity for ALK mutants prevalent in neuroblastoma. We examined PF-06463922 activity in ALK-driven neuroblastoma models in vitro and in vivo. In vitro kinase assays and cell-based experiments examining ALK mutations of increasing potency show that PF-06463922 is an effective inhibitor of ALK with greater activity towards ALK neuroblastoma mutants. In contrast to crizotinib, single agent administration of PF-06463922 caused dramatic tumor inhibition in both subcutaneous and orthotopic xenografts as well as a mouse modelof high-risk neuroblastoma driven by Th-ALKF1174L/MYCN. Taken together, our results suggest PF-06463922 is a potent inhibitor of crizotinib-resistant ALK mutations, and highlights an important new treatment option for neuroblastoma patients. © 2016. Published by The Company of Biologists Ltd.
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| 6. |
- Hagglund, Anna-Carin, et al.
(författare)
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A novel mouse model of anterior segment dysgenesis (ASD) : conditional deletion of Tsc1 disrupts ciliary body and iris development
- 2017
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Ingår i: Disease Models and Mechanisms. - : The Company of Biologists. - 1754-8403 .- 1754-8411. ; 10:3, s. 245-257
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Tidskriftsartikel (refereegranskat)abstract
- Development of the cornea, lens, ciliary body and iris within the anterior segment of the eye involves coordinated interaction between cells originating from the ciliary margin of the optic cup, the overlying periocular mesenchyme and the lens epithelium. Anterior segment dysgenesis (ASD) encompasses a spectrum of developmental syndromes that affect these anterior segment tissues. ASD conditions arise as a result of dominantly inherited genetic mutations and result in both ocular-specific and systemic forms of dysgenesis that are best exemplified by aniridia and Axenfeld-Rieger syndrome, respectively. Extensive clinical overlap in disease presentation amongst ASD syndromes creates challenges for correct diagnosis and classification. The use of animal models has therefore proved to be a robust approach for unravelling this complex genotypic and phenotypic heterogeneity. However, despite these successes, it is clear that additional genes that underlie several ASD syndromes remain unidentified. Here, we report the characterisation of a novel mouse model of ASD. Conditional deletion of Tsc1 during eye development leads to a premature upregulation of mTORC1 activity within the ciliary margin, periocular mesenchyme and lens epithelium. This aberrant mTORC1 signalling within the ciliary margin in particular leads to a reduction in the number of cells that express Pax6, Bmp4 and Msx1. Sustained mTORC1 signalling also induces a decrease in ciliary margin progenitor cell proliferation and a consequent failure of ciliary body and iris development in postnatal animals. Our study therefore identifies Tsc1 as a novel candidate ASD gene. Furthermore, the Tsc1-ablated mouse model also provides a valuable resource for future studies concerning the molecular mechanisms underlying ASD and acts as a platform for evaluating therapeutic approaches for the treatment of visual disorders.
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| 7. |
- Jones, Iwan, et al.
(författare)
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A novel mouse model of tuberous sclerosis complex (TSC) : eye-specific Tsc1-ablation disrupts visual-pathway development
- 2015
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Ingår i: Disease Models and Mechanisms. - : The Company of Biologists. - 1754-8403 .- 1754-8411. ; 8:12, s. 1517-1529
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Tidskriftsartikel (refereegranskat)abstract
- Tuberous sclerosis complex (TSC) is an autosomal dominant syndrome that is best characterised by neurodevelopmental deficits and the presence of benign tumours (called hamartomas) in affected organs. This multi-organ disorder results from inactivating point mutations in either the TSC1 or the TSC2 genes and consequent activation of the canonical mammalian target of rapamycin complex 1 signalling (mTORC1) pathway. Because lesions to the eye are central to TSC diagnosis, we report here the generation and characterisation of the first eye-specific TSC mouse model. We demonstrate that conditional ablation of Tsc1 in eye-committed progenitor cells leads to the accelerated differentiation and subsequent ectopic radial migration of retinal ganglion cells. This results in an increase in retinal ganglion cell apoptosis and consequent regionalised axonal loss within the optic nerve and topographical changes to the contra- and ipsilateral input within the dorsal lateral geniculate nucleus. Eyes from adult mice exhibit aberrant retinal architecture and display all the classic neuropathological hallmarks of TSC, including an increase in organ and cell size, ring heterotopias, hamartomas with retinal detachment, and lamination defects. Our results provide the first major insight into the molecular etiology of TSC within the developing eye and demonstrate a pivotal role for Tsc1 in regulating various aspects of visual-pathway development. Our novel mouse model therefore provides a valuable resource for future studies concerning the molecular mechanisms underlying TSC and also as a platform to evaluate new therapeutic approaches for the treatment of this multi-organ disorder.
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| 8. |
- Kjell, J, et al.
(författare)
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Rat models of spinal cord injury: from pathology to potential therapies
- 2016
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Ingår i: Disease models & mechanisms. - : The Company of Biologists. - 1754-8411 .- 1754-8403. ; 9:10, s. 1125-1137
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Tidskriftsartikel (refereegranskat)abstract
- A long-standing goal of spinal cord injury research is to develop effective spinal cord repair strategies for the clinic. Rat models of spinal cord injury provide an important mammalian model in which to evaluate treatment strategies and to understand the pathological basis of spinal cord injuries. These models have facilitated the development of robust tests for assessing the recovery of locomotor and sensory functions. Rat models have also allowed us to understand how neuronal circuitry changes following spinal cord injury and how recovery could be promoted by enhancing spontaneous regenerative mechanisms and by counteracting intrinsic inhibitory factors. Rat studies have also revealed possible routes to rescuing circuitry and cells in the acute stage of injury. Spatiotemporal and functional studies in these models highlight the therapeutic potential of manipulating inflammation, scarring and myelination. In addition, potential replacement therapies for spinal cord injury, including grafts and bridges, stem primarily from rat studies. Here, we discuss advantages and disadvantages of rat experimental spinal cord injury models and summarize knowledge gained from these models. We also discuss how an emerging understanding of different forms of injury, their pathology and degree of recovery has inspired numerous treatment strategies, some of which have led to clinical trials.
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| 9. |
- Lashley, T., et al.
(författare)
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Molecular biomarkers of Alzheimer's disease: progress and prospects
- 2018
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Ingår i: Disease Models & Mechanisms. - : The Company of Biologists. - 1754-8403 .- 1754-8411. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- The neurodegenerative disorder Alzheimer's disease is characterised by the formation of beta-amyloid plaques and neurofibrillary tangles in the brain parenchyma, which cause synapse and neuronal loss. This leads to clinical symptoms, such as progressive memory deficits. Clinically, these pathological changes can be detected in the cerebrospinal fluid and with brain imaging, although reliable blood tests for plaque and tangle pathologies remain to be developed. Plaques and tangles often co-exist with other brain pathologies, including aggregates of transactive response DNA-binding protein 43 and Lewy bodies, but the extent to which these contribute to the severity of Alzheimer's disease is currently unknown. In this 'At a glance' article and poster, we summarise the molecular biornarkers that are being developed to detect Alzheimer's disease and its related pathologies. We also highlight the biornarkers that are currently in clinical use and include a critical appraisal of the challenges associated with applying these biornarkers for diagnostic and prognostic purposes of Alzheimer's disease and related neurodegenerative disorders, also in their prodromal clinical phases.
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| 10. |
- Olsson, Jan, et al.
(författare)
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HSV presence in brains of individuals without dementia : the TASTY brain series
- 2016
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Ingår i: Disease Models and Mechanisms. - : The Company of Biologists. - 1754-8403 .- 1754-8411. ; 9:11, s. 1349-1355
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Tidskriftsartikel (refereegranskat)abstract
- Herpes simplex virus (HSV) type 1 affects a majority of the population and recent evidence suggests involvement in Alzheimer's disease aetiology. We investigated the prevalence of HSV type 1 and 2 in the Tampere Autopsy Study (TASTY) brain samples using PCR and sero-positivity in plasma, and associations with Alzheimer's disease neuropathology. HSV was shown to be present in human brain tissue in 11/584 (1.9%) of samples in the TASTY cohort, of which six had Alzheimer's disease neuropathological amyloid beta (A beta) aggregations. Additionally, serological data revealed 86% of serum samples tested were IgG-positive for HSV. In conclusion, we report epidemiological evidence of the presence of HSV in brain tissue free from encephalitis symptoms in a cohort most closely representing the general population (a minimum prevalence of 1.9%). Whereas 6/11 samples with HSV DNA in the brain tissue had A beta aggregations, most of those with A beta aggregations did not have HSV present in the brain tissue.
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| 11. |
- Parada-Kusz, M, et al.
(författare)
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Generation of mouse-zebrafish hematopoietic tissue chimeric embryos for hematopoiesis and host-pathogen interaction studies
- 2018
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Ingår i: Disease models & mechanisms. - : The Company of Biologists. - 1754-8411 .- 1754-8403. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- Xenografts of the hematopoietic system are extremely useful as disease models and for translational research. Zebrafish xenografts have been widely used to monitor blood cancer cell dissemination and homing due to the optical clarity of embryos and larvae, which allow unrestricted in vivo visualization of migratory events. Here, we have developed a xenotransplantation technique that transiently generates hundreds of hematopoietic tissue chimeric embryos by transplanting murine bone marrow cells into zebrafish blastulae. In contrast to previous methods, this procedure allows mammalian cell integration into the fish developmental hematopoietic program, which results in chimeric animals containing distinct phenotypes of murine blood cells in both circulation and the hematopoietic niche. Murine cells in chimeric animals express antigens related to i) hematopoietic stem and progenitor cells, ii) active cell proliferation and iii) myeloid cell lineages. We verified the utility of this method by monitoring zebrafish chimeras during development using in vivo non-invasive imaging to show novel murine cell behaviors, such as homing to primitive and definitive hematopoietic tissues, dynamic hematopoietic cell-vascular endothelial and hematopoietic cell-niche interactions, and response to bacterial infection. Overall, transplantation into the zebrafish blastula provides a useful method that simplifies the generation of numerous chimeric animals and expands the range of murine cell behaviors that can be studied in zebrafish chimeras. In addition, integration of murine cells into the host hematopoietic system during development suggests highly conserved molecular mechanisms of hematopoiesis between zebrafish and mammals.
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| 12. |
- Shambat, SM, et al.
(författare)
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Modelling staphylococcal pneumonia in a human 3D lung tissue model system delineates toxin-mediated pathology
- 2015
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Ingår i: Disease models & mechanisms. - : The Company of Biologists. - 1754-8411 .- 1754-8403. ; 8:11, s. 1413-1425
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus necrotizing pneumonia is recognized as a toxin-mediated disease, but yet the tissue destructive events remain elusive partly due to lack of mechanistic studies in human lung tissue. In this study, a 3D tissue model composed of human lung epithelial cells and fibroblasts was used to delineate the role of specific staphylococcal exotoxins in tissue pathology associated with severe pneumonia. To this end, the models were exposed to the mixture of exotoxins produced by S. aureus strains isolated from patients with varying severity of lung infection, namely necrotizing pneumonia or lung empyema, or to purified toxins. The necrotizing pneumonia strains secreted high levels of α-toxin and PVL, and triggered high cytotoxicity, inflammation, necrosis and loss of E-cadherin in the lung epithelium. In contrast, the lung empyema strain produced moderate levels of PVL, but negligible amounts of α-toxin, and triggered limited tissue damage. α-toxin had a direct damaging effect on the epithelium, as verified by toxin-deficient mutants and pure α-toxin. Moreover, PVL contributed to pathology through the lysis of neutrophils, and a combination of α-toxin and PVL resulted in the most severe epithelial injury. In addition, toxin-induced release of pro-inflammatory mediators from lung tissue models resulted in enhanced neutrophil migration. Using a collection of 31 strains from patients with staphylococcal pneumonia revealed that strains producing high levels of α-toxin and PVL were cytotoxic and associated with fatal outcome. Also, the strains that produced the highest toxin levels induced significantly greater epithelial disruption. Of importance, toxin-mediated lung epithelium destruction could be inhibited by polyspecific intravenous immunoglobulin containing antibodies against α-toxin and PVL. This study introduces a novel model system for studies of staphylococcal pneumonia in a human setting, and the results revealed that a combination and levels of α-toxin and PVL correlate with tissue pathology and clinical outcome associated with pneumonia.
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| 13. |
- Strassman, Alexander, et al.
(författare)
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Generation of a multipurpose Prdm16 mouse allele by targeted gene trapping
- 2017
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Ingår i: Disease Models and Mechanisms. - : The Company of Biologists. - 1754-8403 .- 1754-8411. ; 10:7, s. 909-922
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Tidskriftsartikel (refereegranskat)abstract
- Gene trap mutagenesis is a powerful tool to create loss-of-function mutations in mice and other model organisms. Modifications of traditional gene trap cassettes, including addition of conditional features in the form of Flip-excision (FlEx) arrays to enable directional gene trap cassette inversions by Cre and Flpe site-specific recombinases, greatly enhanced their experimental potential. By taking advantage of these conditional gene trap cassettes, we developed a generic strategy for generating conditional mutations and validated this strategy in mice carrying a multipurpose allele of the Prdm16 transcription factor gene. We demonstrate that the gene trap insertion creates a null mutation replicating the Pierre Robin sequence-type cleft palate phenotype of other Prdm16 mutant mice. Consecutive breeding to Flpe and Emx1(IREScre) deleter mice spatially restricted Prdm16 loss to regions of the forebrain expressing the homeobox gene Emx1, demonstrating the utility of the technology for the analysis of tissue-specific gene functions.
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| 14. |
- Vanherp, L, et al.
(författare)
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Sensitive bioluminescence imaging of fungal dissemination to the brain in mouse models of cryptococcosis
- 2019
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Ingår i: Disease models & mechanisms. - : The Company of Biologists. - 1754-8411 .- 1754-8403. ; 12:6
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Tidskriftsartikel (refereegranskat)abstract
- Cryptococcus neoformans is a leading cause of fungal brain infections, but the mechanism of dissemination and dynamics of cerebral infection following pulmonary disease are poorly understood. To address these questions, non-invasive techniques that can study the dynamic processes of disease development and progression in living animal models or patients are required. As such, bioluminescence imaging (BLI) has emerged as a powerful tool to evaluate the spatial and temporal distribution of infection in living animals. We aimed at studying the time profile of the dissemination of cryptococcosis from the lung to the brain in murine models by engineering the first bioluminescent C. neoformans KN99α strain expressing a sequence-optimized red-shifted luciferase. The high pathogen-specificity and sensitivity of BLI was complemented with the three-dimensional anatomical information from micro-computed tomography (CT) of the lung and magnetic resonance imaging (MRI) of the brain. These non-invasive imaging techniques provided longitudinal read-outs on the spatial and temporal distribution of infection following intravenous, intranasal or endotracheal routes of inoculation. Furthermore, the imaging results correlated strongly with the fungal load in the respective organs. By obtaining dynamic and quantitative information about the extent and timing of brain infections for individual animals, we found that dissemination to the brain after primary infection of the lung is likely a late-stage event with a time frame that is variable between animals. This novel tool in Cryptococcus research can aid the identification of host and pathogen factors involved in this process and supports development of novel preventive or therapeutic approaches.
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| 15. |
- Yau, ACY, et al.
(författare)
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Rheumatoid arthritis: identifying and characterising polymorphisms using rat models
- 2016
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Ingår i: Disease models & mechanisms. - : The Company of Biologists. - 1754-8411 .- 1754-8403. ; 9:10, s. 1111-1123
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Tidskriftsartikel (refereegranskat)abstract
- Rheumatoid arthritis is a chronic inflammatory joint disorder characterised by erosive inflammation of the articular cartilage and by destruction of the synovial joints. It is regulated by both genetic and environmental factors, and, currently, there is no preventative treatment or cure for this disease. Genome-wide association studies have identified ∼100 new loci associated with rheumatoid arthritis, in addition to the already known locus within the major histocompatibility complex II region. However, together, these loci account for only a modest fraction of the genetic variance associated with this disease and very little is known about the pathogenic roles of most of the risk loci identified. Here, we discuss how rat models of rheumatoid arthritis are being used to detect quantitative trait loci that regulate different arthritic traits by genetic linkage analysis and to positionally clone the underlying causative genes using congenic strains. By isolating specific loci on a fixed genetic background, congenic strains overcome the challenges of genetic heterogeneity and environmental interactions associated with human studies. Most importantly, congenic strains allow functional experimental studies be performed to investigate the pathological consequences of natural genetic polymorphisms, as illustrated by the discovery of several major disease genes that contribute to arthritis in rats. We discuss how these advances have provided new biological insights into arthritis in humans.
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