Abstract
Inflammatory infiltrates are seen in a variety of cardiovascular conditions in man and in animal models of these conditions. Current immunohistochemical methods using tissue sections for characterizing the cells in mice that comprise these infiltrates are time-consuming, do not yield robust quantitative data, and may not give results representative of the entire organ. Investigators at Johns Hopkins have developed an improved technique for quantifying inflammatory infiltrates in the hearts of mice. Briefly, the heart is perfused with a calcium-free bicarbonate buffer and digested with a mixture of proteases. Cells are then manually dispersed, filtered, and stained for flow cytometry (CD45, CD44, CD3, CD4, CD8, CD19, CD11b, MHC II, Gr1). When applied to studies of experimental autoimmune myocarditis, the technique revealed a clear association between the type and extent of inflammatory infiltrate and cardiac function. This technique is sensitive and reproducible; it will be valuable for determining the number and types of inflammatory cells in the hearts of experimental mice with a variety of cardiac conditions.
Afanasyeva M, Georgapoulos D, Belardi DF, Ramsundar AC, Barin JG, Kass DA, Rose NR: Quantitative analysis of myocardial inflammation by flow cytometry in murine autoimmune myocarditis. Correlation with cardiac function. Am J Pathol 164:807–815, 2004
The cellular oncogene c-kit encodes KIT, the stem cell factor receptor. Scientists in Italy examined the expression and distribution of KIT in normal (eight organs) and neoplastic (107 tumors) tissues of the dog and cat. For these immunohistochemical studies, a rabbit polyclonal antibody raised against the highly conserved c-kit intracellular domain was employed. Tumors were considered positive for KIT if more than 5% of the tumor cells were immunoreactive; immunoreactivity was membranous, cytoplasmic, paranuclear, or nuclear. The studies revealed strongly positive staining in the following normal tissues of both species: mast cells, Purkinje cells of the cerebellum, and interstitial cells of Cajal in the gastrointestinal tract. Mast cell tumors and a subset of gastrointestinal stromal tumors of both the dog and cat were the most strongly labeled neoplastic tissues. These studies demonstrate that staining for KIT is a reliable and useful diagnostic technique when applied to canine and feline tissues.
Morini M, Bettini G, Preziosi R, Mandriolo L: C-kit gene product (CD117) immunoreactivity in canine and feline paraffin sections. J Histochem Cytochem 52:705–708, 2004
Many factors influence the magnitude, duration, and efficacy of the immune response to viruses. Recent studies demonstrate that the rate of viral replication can be important in determining the host cytotoxic lymphocyte (CTL) response. Slowly replicating viruses may actually evade immune surveillance. In a murine model of lymphocytic choriomeningitis virus infection and in clinical cases of human hepatitis C virus infection, slower replicating strains of virus induced weaker host CTL responses and persisted longer in the host than more rapidly replicating strains. Moreover, the clinical outcome of hepatitis C infection in patients was strongly associated with the rate of viral replication. These results indicate that the growth rate of viruses may be an important determinant of host immune response and that slower viral replication may be advantageous for the persistence of some pathogens.
Bocharov G, Ludewig B, Bertoletti A, Klenerman P, Junt T, Krebs P, Luzyanina T, Fraser C, Anderson RM: Underwhelming the immune response: effect of slow virus growth on CD7+-T-lymphocyte responses. J Virol 78:2247–2254, 2004
Use of the mouse as a model for lung cancer has been hampered by the fact that mice do not develop squamous cell carcinoma (SCC) of the lung, a major subtype of human lung cancers. However, a new murine model of chemically induced lung SCC has recently been reported. Investigators applied N-nitroso-tris-chloroethylurea to the skin of mice and observed preneoplastic and neoplastic changes, including the development of SCC, in the lung. Not all strains of mice were susceptible to induction of SCC of the lung with this protocol. The investigators took advantage of strain-related differences in susceptibility to identify SCC susceptibility loci. This new murine model will be valuable in testing chemoprevention strategies applicable to human populations.
Wang Y, Zhang Z, Yan Y, Lemon WJ, LaRegina M, Morrison C, Lubet R, You M: A chemically induced model for squamous cell carcinoma of the lung in mice. Cancer Res 64:1647–1654, 2004
Transmissible spongiform encephalopathies (TSE) are progressive neurodegenerative diseases that affect both humans and ruminants. The infectious disease agents are prions. Of particular public health concern is the emerging disease bovine spongiform encephalopathy (BSE) that can apparently be transmitted from cattle to man and is associated with variant Creutzfeldt-Jakob disease in man. Italian investigators recently reported the identification of a second BSE syndrome. Unlike previously described forms of BSE, this disease is characterized by the formation of prion protein-containing amyloid plaques in the thalamus, cerebral cortices, and olfactory bulb of affected cattle. The biochemical characteristics of the prion protein associated with this new syndrome differ considerably from the characteristics of prions associated with previously described BSE cases. Moreover, this newly discovered prion protein is very similar biochemically to prion proteins described in some cases of sporadic Creutzfeldt-Jakob disease in man.
Casalone C, Zanusso G, Acutis P, Ferrari S, Capucci L, Taglivini F, Monaco S, Carameli M: Identification of a second bovine amyloidotic spongiform encephalopathy: molecular similarities with sporadic Creuzfeldt-Jakob disease. Proc Natl Acad Sci USA 101:3065–3070, 2004
A large international consortium recently released the nearly complete genome sequence of the Brown Norway rat. The rat genome is slightly smaller than the human genome and somewhat larger than the mouse genome. The rat genome shares several features with the genomes of the mouse and man, including similar numbers of genes and an ancestral eutherian core of approximately 109 nucleotides containing the majority of coding and regulatory sequences. About 30% of the rat genome consists of rodent-specific elements also found in the mouse but not in man. It is clear from comparing the three genomes that more genetic changes have occurred in rodents than in man since they diverged from their last common ancestor. Genetic elements that have been expanded in the rat include genes encoding molecules important in olfaction, sexual selection, detoxification of exogenous compounds, and proteolysis. Of particular interest is the fact that orthologues of most of the genes known to be associated with disease in humans have been identified in the rat.
Rat Genome Sequencing Project Consortium: Genome sequence of the Brown Norway rat yields insights into mammalian evolution. Nature 428:493–521, 2004