Animal Models Of Human Disease Research Articles

Molecular scissors and their application in genetically modified farm animals.

Molecular scissors (MS), incl. Zinc Finger Nucleases (ZFN), Transcription-activator like endoncleases (TALENS) and meganucleases possess long recognition sites and are thus capable of cutting DNA in a very specific manner. These molecular scissors mediate targeted genetic alterations by enhancing the DNA mutation rate via induction of double-strand breaks at a predetermined genomic site. Compared to conventional homologous recombination based gene targeting, MS can increase the targeting rate 10,000-fold, and gene disruption via mutagenic DNA repair is stimulated at a similar frequency. The successful application of different MS has been shown in different organisms, including insects, amphibians, plants, nematodes, and mammals, including humans. Recently, another novel class of molecular scissors was described that uses RNAs to target a specific genomic site. The CRISPR/Cas9 system is capable of targeting even multiple genomic sites in one shot and thus could be superior to ZFNs or TALEN, especially by its easy design. MS can be successfully employed for improving the understanding of complex physiological systems, producing transgenic animals, incl. creating large animal models for human diseases, creating specific cell lines, and plants, and even for treating human genetic diseases. This review provides an update on molecular scissors, their underlying mechanism and focuses on new opportunities for generating genetically modified farm animals.

Advances in genetic modification of farm animals using zinc-finger nucleases (ZFN).

Genome editing tools (GET), including zinc-finger nucleases (ZFN), transcription activator-like endonucleases (TALENS), and meganucleases possess long recognition sites and are thus capable of cutting DNA in a very specific manner. These genome editing tools mediate targeted genetic alterations by enhancing DNA mutation frequency via induction of double-strand breaks at a predetermined genomic site. Compared to conventional homologous recombination based gene targeting, GETs can increase gene targeting and gene disruption via mutagenic DNA repair more than 10,000-fold. Recently, a novel class of genome editing tools was described that uses RNAs to target a specific genomic site. The CRISPR/Cas9 system is capable of targeting even multiple genomic sites in one shot and thus could be superior to ZFNs or TALEN. Current results indicate that these tools can be successfully employed in a broad range of organisms which renders them useful for improving the understanding of complex physiological systems, producing transgenic animals, including creating large animal models for human diseases, creating specific cell lines, and plants, and even for treating human genetic diseases. This review provides an update on the use of ZFNs to modify the genome of farm animals, summarizes current knowledge on the underlying mechanism, and discusses new opportunities for generating genetically modified farm animals.

A Computational Pipeline for Cross-Species Analysis of RNA-seq Data Using R and Bioconductor.

RNA sequencing (RNA-seq) has revolutionized transcriptome analysis through profiling the expression of thousands of genes at the same time. Systematic analysis of orthologous transcripts across species is critical for understanding the evolution of gene expression and uncovering important information in animal models of human diseases. Several computational methods have been published for analyzing gene expression between species, but they often lack crucial details and therefore cannot serve as a practical guide. Here, we present the first step-by-step protocol for cross-species RNA-seq analysis with a concise workflow that is largely based on the free open-source R language and Bioconductor packages. This protocol covers the entire process from short-read mapping, gene expression quantification, differential expression analysis to pathway enrichment. Many useful utilities for data visualization are included. This complete and easy-to-follow protocol provides hands-on guidance for users who are new to cross-species gene expression analysis.

Inhibition of Apoptosis and Efficacy of Pan Caspase Inhibitor, Q-VD-OPh, in Models of Human Disease.

Apoptosis is physiological cell death required for the cellular maintenance of homeostasis, and caspases play a major role in the execution of this process. Numerous disorders occur when levels of apoptosis within an organism are excessive, and several studies have explored the possibility of using caspase inhibitors to prevent these disorders. Q-VD-OPh (quinolyl-valyl-O-methylaspartyl-[2,6-difluorophenoxy]-methyl ketone), a novel pan caspase inhibitor, has been used because of its efficacy to inhibit apoptosis at low concentrations, its ability to cross the blood–brain barrier, as well as being nontoxic in vivo. This review examines Q-VD-OPh’s ability to inhibit apoptosis in several animal models of human disease.

Comparative analysis of growth characteristics of Sprague Dawley rats obtained from different sources.

Genetic background in animal models is an intrinsic research variable in biomedical research. Although inbred strains offer genetic uniformity, the outbred stocks, known for genetic variability are often used to develop animal models of human disease. The genetic variability is considered to be even higher when outbred stocks are obtained from different sources. In order to examine the degree of variability of an outbred stock obtained from various sources, Sprague Dawley (SD) rat lines obtained from two sources were evaluated for their growth characteristics. The SD rats from Charles River laboratories (CRL) and Harlan Laboratories (HAR) were monitored for weight gain from the age of 6 weeks to 24 weeks. Food intake was monitored between 13 and 24 weeks. Body composition, organ weights, tibial lengths and blood parameters were measured. There was no difference observed in food intake per 100 gram body weight at most of the time points. CRL rats showed higher body fat mass (49.6%), higher gross liver weights (22.2%), lower testicular weights (30.8%) and lower cholesterol levels (25.4%) than HAR rats. Phenotypic differences may be attributed to genetic heterogeneity of the SD outbred stock between the two sources and represent a significant research variable impacting studies especially related to metabolic diseases. Therefore, in order the minimize research variables for those studies where genetic diversity is not a basis for experimental design, the use of single source genetically uniform inbred animal models is highly recommended over the use of outbred stocks.

Similarity-based search of model organism, disease and drug effect phenotypes.

BackgroundSemantic similarity measures over phenotype ontologies have been demonstrated to provide a powerful approach for the analysis of model organism phenotypes, the discovery of animal models of human disease, novel pathways, gene functions, druggable therapeutic targets, and determination of pathogenicity.ResultsWe have developed PhenomeNET 2, a system that enables similarity-based searches over a large repository of phenotypes in real-time. It can be used to identify strains of model organisms that are phenotypically similar to human patients, diseases that are phenotypically similar to model organism phenotypes, or drug effect profiles that are similar to the phenotypes observed in a patient or model organism. PhenomeNET 2 is available at http://aber-owl.net/phenomenet.ConclusionsPhenotype-similarity searches can provide a powerful tool for the discovery and investigation of molecular mechanisms underlying an observed phenotypic manifestation. PhenomeNET 2 facilitates user-defined similarity searches and allows researchers to analyze their data within a large repository of human, mouse and rat phenotypes.

Zebrafish Myofilaments and their Assemblies are Good Structural Models for Studying Disease Mutations

Zebrafish have become a prominent animal model of human disease because of their genetic tractability and rapid development (Lieschke & Currie, 2007). Several muscle diseases have been studied using zebrafish, including muscular dystrophy (Johnson et al., 2013), hypertrophic and dilated cardiomyopathy, nemaline myopathy (Sehnert et al., 2002; Asnani & Peterson, 2014; Telfer et al., 2012) and distal arthrogryposis (Ha et al., 2013). Here we show that zebrafish myofilaments and their assemblies have molecular structures similar to those of higher vertebrates, demonstrating their usefulness in elucidating structural changes due to disease mutations. EM and 3D reconstruction have shown that striated muscle contraction is regulated by Ca2+-induced movement of tropomyosin on thin filaments, which uncovers myosin-binding sites on actin. Using negative staining EM and single particle reconstruction we find that tropomyosin is well resolved in zebrafish native thin filaments and undergoes the same Ca2+-induced movement as seen in other species. Zebrafish thin filaments are therefore good models for studying the impact of thin filament mutations (actin, troponin, tropomyosin, nebulin) on thin filament structure and regulation. Thick filaments are also readily isolated from zebrafish muscle and their 3D reconstruction is similar to that of mammalian filaments (González-Solá et al., 2014). We have isolated intact filament assemblies (myofibrils and A-segments) from zebrafish and find that these also closely resemble those of other vertebrates, including mammals, clearly revealing MyBP-C and M-line periodic organization. These are therefore good models for elucidating the structural impact of mutations in myosin, MyBP-C and M-line proteins. We conclude that the structures of zebrafish skeletal muscle thick and thin filaments and their native assemblies closely resemble those of higher vertebrates, making them excellent models for studying the molecular impact of disease-causing mutations on filament structure.

Feline foamy virus adversely affects feline mesenchymal stem cell culture and expansion: implications for animal model development.

Mesenchymal stem cells (MSCs) are a promising therapeutic option for various immune-mediated and inflammatory disorders due to their potent immunomodulatory and trophic properties. Naturally occurring diseases in large animal species may serve as surrogate animal models of human disease, as they may better reflect the complex genetic, environmental, and physiologic variation present in outbred populations. We work with naturally occurring diseases in large animal species to better understand how MSCs work and to facilitate optimal translation of MSC-based therapies. We are investigating the use of MSC therapy for a chronic oral inflammatory disease in cats. During our efforts to expand fat-derived feline MSCs (fMSCs), we observed that∼50% of the cell lines developed giant foamy multinucleated cells in later passages. These morphologic alterations were associated with proliferation arrest. We hypothesized that the cytopathic effects were caused by infection with a retrovirus, feline foamy virus (FFV). Using transmission electron microscopy, polymerase chain reaction, and in vitro assays, we determined that syncytial cell formation and proliferation arrest in fMSCs were caused by FFV strains that were highly homologous to previously reported FFV strains. We determined that the antiretroviral drug, tenofovir, may be used to support ex vivo expansion and salvage of FFV-infected fMSC lines. MSC lines derived from specific pathogen-free cats do not appear to be infected with FFV and may be a source of allogeneic fMSCs for clinical application. FFV infection of fMSC lines may hinder large-scale expansion of autologous MSC for therapeutic use in feline patients.

Hydrolysate from eggshell membrane ameliorates intestinal inflammation in mice.

Inflammatory bowel diseases (IBD) comprises of ulcerative colitis (UC) and Cohn’s disease (CD) as two main idiopathic pathologies resulting in immunologically mediated chronic inflammatory conditions. Several bioactive peptides and hydro lysates from natural sources have now been tested in animal models of human diseases for potential anti-inflammatory effects. Eggshell membrane (ESM) is a well-known natural bioactive material. In this study, we aim to study the anti-inflammatory activity of ESM hydro lysate (AL-PS) in vitro and in vivo. In vitro, AL-PS was shown to inhibit pro-inflammatory cytokine IL-8 secretion. In vivo treatment with AL-PS was shown to reduce dextran sodium sulphate (DSS)-induced weight loss, clinical signs of colitis and secretion of interleukin (IL)-6 (p < 0.05). In addition, treatment with AL-PS also attenuated the severity of intestinal inflammation via down-regulation of IL-10 an anti-inflammatory cytokine. This validates potential benefits of AL-PS as a novel preventative target molecule for treatment of IBD.

Genetic analysis of the cardiac methylome at single nucleotide resolution in a model of human cardiovascular disease.

Epigenetic marks such as cytosine methylation are important determinants of cellular and whole-body phenotypes. However, the extent of, and reasons for inter-individual differences in cytosine methylation, and their association with phenotypic variation are poorly characterised. Here we present the first genome-wide study of cytosine methylation at single-nucleotide resolution in an animal model of human disease. We used whole-genome bisulfite sequencing in the spontaneously hypertensive rat (SHR), a model of cardiovascular disease, and the Brown Norway (BN) control strain, to define the genetic architecture of cytosine methylation in the mammalian heart and to test for association between methylation and pathophysiological phenotypes. Analysis of 10.6 million CpG dinucleotides identified 77,088 CpGs that were differentially methylated between the strains. In F1 hybrids we found 38,152 CpGs showing allele-specific methylation and 145 regions with parent-of-origin effects on methylation. Cis-linkage explained almost 60% of inter-strain variation in methylation at a subset of loci tested for linkage in a panel of recombinant inbred (RI) strains. Methylation analysis in isolated cardiomyocytes showed that in the majority of cases methylation differences in cardiomyocytes and non-cardiomyocytes were strain-dependent, confirming a strong genetic component for cytosine methylation. We observed preferential nucleotide usage associated with increased and decreased methylation that is remarkably conserved across species, suggesting a common mechanism for germline control of inter-individual variation in CpG methylation. In the RI strain panel, we found significant correlation of CpG methylation and levels of serum chromogranin B (CgB), a proposed biomarker of heart failure, which is evidence for a link between germline DNA sequence variation, CpG methylation differences and pathophysiological phenotypes in the SHR strain. Together, these results will stimulate further investigation of the molecular basis of locally regulated variation in CpG methylation and provide a starting point for understanding the relationship between the genetic control of CpG methylation and disease phenotypes.

323 ESTROGEN-INDUCED EPITHELIAL-MESENCHYMAL TRANSITION AND EXPRESSION OF PROAPOPTOTIC MARKERS IN PORCINE STEM CELLS

In transgenic pig production for generating animal models of human diseases, apoptosis of early implantation embryo disturbs the transgenic pig production. In general, epithelial-mesenchymal transition (EMT) is considered important in embryo development and apoptosis. In addition, it was reported that 17β-oestradiol (E2), among hormones that participate in early implantation of embryo, could induce EMT and neural differentiation in mouse embryonic stem cells. Therefore, in this study, we examined the effects of the steroid hormone, E2, in the changes of EMT and apoptotic markers in porcine embryonic stem cells (pESC) and porcine induced pluripotent stem cells (piPSC). During the study, we cultured pESC and piPSC in pESC media containing basic fibroblast growth factor (b-FGF) and leukemia inhibitory factor (LIF) and performed RT-PCR and an alkaline phophatase (AP) test to measure pluripotent and undifferentiation markers of these porcine stem cells. The RT-PCR results showed that OCT4, NANOG, and SOX2 were expressed in these pESC and piPSC, indicating their pluripotency as stem cells. Also, these porcine stem cells showed positive AP activity, demonstrating undifferentiation. Additionally, we treated pESC and piPSC with E2 to examine effects of steroid hormone on the changes of EMT and apoptotic markers (i.e. bcl-2, bax, E-cad, and vimentin). The E2 treatment increased the expression of vimentin and bcl-2, while decreased the expression of E-cadherin and bax. By using immunocytochemistry (ICC), we examined the protein expression of EMT markers, which are vimentin and E-cadherin at the translational level, and found that expression of vimentin protein was increased while E-cadherin protein level was reduced at periphery of the colonies in pESC and piPSC. In conclusion, these results indicate that E2 can promote EMT process and reverse apoptosis in these pESC and iPSC. In a future study, we will further examine the effects of progesterone on the expressions of EMT and apoptotic markers in pESC and piPSC. Consequently, this study will contribute to elucidate the underlying mechanisms of EMT and apoptosis controlled by steroid hormones in porcine stem cells.

Poikilocytosis in rabbits: prevalence, type, and association with disease.

Rabbits (Oryctolagus cuniculus) are a popular companion animal, food animal, and animal model of human disease. Abnormal red cell shapes (poikilocytes) have been observed in rabbits, but their significance is unknown. The objective of this study was to investigate the prevalence and type of poikilocytosis in pet rabbits and its association with physiologic factors, clinical disease, and laboratory abnormalities. We retrospectively analyzed blood smears from 482 rabbits presented to the University of California-Davis Veterinary Medical Teaching Hospital from 1990 to 2010. Number and type of poikilocytes per 2000 red blood cells (RBCs) were counted and expressed as a percentage. Acanthocytes (>3% of RBCs) were found in 150/482 (31%) rabbits and echinocytes (>3% of RBCs) were found in 127/482 (27%) of rabbits, both healthy and diseased. Thirty-three of 482 (7%) rabbits had >30% acanthocytes and echinocytes combined. Mild to moderate (>0.5% of RBCs) fragmented red cells (schistocytes, microcytes, keratocytes, spherocytes) were found in 25/403 (6%) diseased and 0/79 (0%) healthy rabbits (P = 0.0240). Fragmentation and acanthocytosis were more severe in rabbits with inflammatory disease and malignant neoplasia compared with healthy rabbits (P<0.01). The % fragmented cells correlated with % polychromasia, RDW, and heterophil, monocyte, globulins, and fibrinogen concentrations (P<0.05). Echinocytosis was significantly associated with renal failure, azotemia, and acid-base/electrolyte abnormalities (P<0.05). Serum cholesterol concentration correlated significantly with % acanthocytes (P<0.0001), % echinocytes (P = 0.0069), and % fragmented cells (P = 0.0109), but correlations were weak (Spearman ρ <0.02). These findings provide important insights into underlying pathophysiologic mechanisms that appear to affect the prevalence and type of naturally-occurring poikilocytosis in rabbits. Our findings support the need to carefully document poikilocytes in research investigations and in clinical diagnosis and to determine their diagnostic and prognostic value.

Experimental primates and non-human primate (NHP) models of human diseases in China: current status and progress.

Non-human primates (NHPs) are phylogenetically close to humans, with many similarities in terms of physiology, anatomy, immunology, as well as neurology, all of which make them excellent experimental models for biomedical research. Compared with developed countries in America and Europe, China has relatively rich primate resources and has continually aimed to develop NHPs resources. Currently, China is a leading producer and a major supplier of NHPs on the international market. However, there are some deficiencies in feeding and management that have hampered China's growth in NHP research and materials. Nonetheless, China has recently established a number of primate animal models for human diseases and achieved marked scientific progress on infectious diseases, cardiovascular diseases, endocrine diseases, reproductive diseases, neurological diseases, and ophthalmic diseases, etc. Advances in these fields via NHP models will undoubtedly further promote the development of China's life sciences and pharmaceutical industry, and enhance China's position as a leader in NHP research. This review covers the current status of NHPs in China and other areas, highlighting the latest developments in disease models using NHPs, as well as outlining basic problems and proposing effective countermeasures to better utilize NHP resources and further foster NHP research in China.

Leaky gut, microbiota, and cancer: an incoming hypothesis.

Multigenic disease development is dependent on both missing and overactivated pathways, just as the homeostasis of our body systems is the product of many complex, redundant mechanisms. The goal of finding a common factor in the disease pathogenesis is difficult, as genetic and pathophysiological data are still incomplete, and the individual variability is enormous. Nevertheless, the examination of the role of human microbiota in illnesses using animal models of human diseases reared in defined (gnotobiotic) conditions could allow insight into the unusual complexity of the mechanisms involved in the initiation and maintenance of chronic diseases, including cancer. Although the most important findings in this fascinating field are still to come, a hypothesis, which is more than speculative, can be made, as it is clear that our bacterial companions affect our fates more than previously assumed.

PTEN/PIK3CA genes are frequently mutated in spontaneous and medroxyprogesterone acetate-accelerated 7,12-dimethylbenz(a)anthracene-induced mammary tumours of tree shrews

Tree shrew has increasingly become an attractive experimental animal model for human diseases, particularly for breast cancer due to spontaneous breast tumours and their close relationship to primates and by extension to humans. However, neither normal mammary glands nor breast tumours have been well characterised in the Chinese tree shrew (Tupaia belangeri chinensis). In this study, normal mammary glands from four different developmental stages and 18 spontaneous breast tumours were analysed. Haematoxylin and eosin (H&E) staining and immunohistochemistry (IHC) showed that normal mammary gland morphology and structures of tree shrews were quite similar to those found in humans. Spontaneous breast tumours of tree shrews were identified as being intraductal papilloma, papillary carcinoma, and invasive ductal carcinoma with or without lung metastasis. To further analyse breast cancer tumours among tree shrews, 40 3–4month-old female tree shrews were orally administrated 20mg 7,12-dimethylbenz(a)anthracene (DMBA) or peanut oil thrice, and then, 15 of these DMBA administrated tree shrews were implanted with medroxyprogesterone acetate (MPA) pellets. DMBA was shown to induce breast tumours (12%) while the addition of MPA increased the tumour incidence (50%). Of these, three induced breast tumours were intraductal papillary carcinomas and one was invasive ductal carcinoma (IDC). The PTEN/PIK3CA (phosphatase and tensin homologue/phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha), but not TP53 and GATA3, genes are frequently mutated in breast tumours, and the PTEN/PIK3CA gene mutation status correlated with the expression of pAKT in tree shrew breast tumours. These results suggest that tree shrews may be a promising animal model for a subset of human breast cancers with PTEN/PIK3CA gene mutations.

Hemichannels; from the molecule to the function.

Coordinated cell interactions are required to accomplish diverse complex and dynamic tasks of several tissues in vertebrates and invertebrates. Cell functions, such as intercellular propagation of calcium waves and spread of electrotonic potentials, are coordinated by cell-to-cell communication through gap junction channels (GJCs). These channels are formed by the serial docking of two hemichannels (HCs), which in vertebrates are formed by six protein subunits called connexins (Cxs). In humans, a gene family encodes 21 different proteins with a highly variable C-terminal where most posttranslational modifications occur. Among them protein phosphorylation and/or oxidation (e.g., nitrosylation) induces functional changes. Currently, it is believed that undocked HCs may have functional relevance in cell physiology allowing diffusional exchange of ions and small molecules between intra- and extra-cellular compartments. In support to this new concept, it has been shown that controlled HC opening allows the release of small signaling molecules (e.g., ATP, glutamate, NAD+, adenosine, and cyclic nucleotides) and uptake of metabolically relevant molecules (e.g., glucose). Additionally, a growing body of evidences shows that HCs are involved in important and diverse processes, such PGE2 release from osteocytes, glucose detection in tanicytes, T cell infection with AIDS virus, memory consolidation in the basolateral amygdala and release of nitric oxide from endothelial cells, among others. However, HCs can also play an important role in the homeostatic imbalance observed in diverse diseases. In fact, enhanced HCs opening induces or accelerates cell death in several pathological conditions. Hemichannel-mediated cell death is due mainly to Ca+2 influx and cellular overload. The latter activates proteases, nucleases and lipases, causing irreversible cell damage. Accordingly, blockade of HCs reduces the cellular damage observed in several animal models of human diseases. Additionally, another family of proteins called pannexins (Panxs) also forms channels at the plasma membrane and some of their functional and pharmacological sensitivities overlap with those of Cx HCs. Recently, Panx channels have been involved in both pathological and physiological processes. Therefore, Cx HCs and Panx channels appear as promising drug targets for clinical treatment of several inherited and acquired human diseases. This research topic gathers 11 articles that give a broad view about the role of Cx- and Panx–based channels from purified molecules reconstituted in a lipid environment and posttranslational regulation, to physiological and pathological implications. In addition, it proposes a putative molecular explanation of HC malfunctioning in specific diseases. Conflict of interest statement The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Bacterial differentiation, development, and disease: mechanisms for survival.

Bacteria have the exquisite ability to maintain a precise diameter, cell length, and shape. The dimensions of bacteria size and shape are a classical metric in the distinction of bacterial species. Much of what we know about the particular morphology of any given species is the result of investigations of planktonic cultures. As we explore deeper into the natural habitats of bacteria, it is increasingly clear that bacteria can alter their morphology in response to the environment in which they reside. Specific morphologies are also becoming recognized as advantageous for survival in hostile environments. This is of particular importance in the context of both colonization and infection in the host. There are multiple examples of bacterial pathogens that use morphological changes as a mechanism for evasion of host immune responses and continued persistence. This review will focus on two systems where specific morphological changes are essential for persistence in animal models of human disease. We will also offer insight into the mechanism underlying the morphological changes and how these morphotypes aid in persistence. Additional examples of morphological changes associated with survival will be presented.

Western blot analysis of BK channel β1-subunit expression should be interpreted cautiously when using commercially available antibodies.

Large conductance Ca2+‐activated K+ (BK) channels consist of pore‐forming α‐ and accessory β‐subunits. There are four β‐subunit subtypes (β1–β4), BK β1‐subunit is specific for smooth muscle cells (SMC). Reduced BK β1‐subunit expression is associated with SMC dysfunction in animal models of human disease, because downregulation of BK β1‐subunit reduces channel activity and increases SMC contractility. Several anti‐BK β1‐subunit antibodies are commercially available; however, the specificity of most antibodies has not been tested or confirmed in the tissues from BK β1‐subunit knockout (KO) mice. In this study, we tested the specificity and sensitivity of six commercially available antibodies from five manufacturers. We performed western blot analysis on BK β1‐subunit enriched tissues (mesenteric arteries and colons) and non‐SM tissue (cortex of kidney) from wild‐type (WT) and BK β1‐KO mice. We found that antibodies either detected protein bands of the appropriate molecular weight in tissues from both WT and BK β1‐KO mice or failed to detect protein bands at the appropriate molecular weight in tissues from WT mice, suggesting that these antibodies may lack specificity for the BK β1‐subunit. The absence of BK β1‐subunit mRNA expression in arteries, colons, and kidneys from BK β1‐KO mice was confirmed by RT‐PCR analysis. We conclude that these commercially available antibodies might not be reliable tools for studying BK β1‐subunit expression in murine tissues under the denaturing conditions that we have used. Data obtained using commercially available antibodies should be interpreted cautiously. Our studies underscore the importance of proper negative controls in western blot analyses.

Exploiting ovine immunology to improve the relevance of biomedical models

Animal models of human disease are important tools in many areas of biomedicine; for example, in infectious disease research and in the development of novel drugs and medical devices. Most studies involving animals use rodents, in particular congenic mice, due to the availability of a wide number of strains and the ease with which they can be genetically manipulated. The use of mouse models has led to major advances in many fields of research, in particular in immunology but despite these advances, no animal model can exactly reproduce all the features of human disease. It is increasingly becoming recognised that in many circumstances mice do not provide the best model and that alternative species may be more appropriate. Here, we describe the relative merits of sheep as biomedical models for human physiology and disease in comparison to mice, with a particular focus on reproductive and respiratory pathogens.

Adaptive SPECT imaging with crossed-slit apertures.

Preclinical single-photon emission computed tomography (SPECT) is an essential tool for studying the progression, response to treatment, and physiological changes in small animal models of human disease. The wide range of imaging applications is often limited by the static design of many preclinical SPECT systems. We have developed a prototype imaging system that replaces the standard static pinhole aperture with two sets of movable, keel-edged copper-tungsten blades configured as crossed (skewed) slits. These apertures can be positioned independently between the object and detector, producing a continuum of imaging configurations in which the axial and transaxial magnifications are not constrained to be equal. We incorporated a megapixel silicon double-sided strip detector to permit ultrahigh-resolution imaging. We describe the configuration of the adjustable slit aperture imaging system and discuss its application toward adaptive imaging, and reconstruction techniques using an accurate imaging forward model, a novel geometric calibration technique, and a GPU-based ultra-high-resolution reconstruction code.