Role of macrophages in experimental group B streptococcal arthritis

Septic arthritis is a clinical manifestation of group B Streptococcus (GBS) infection in both neonates and adults. Because macrophages are known to participate in tissue injury, the role of this cell population in GBS-induced arthritis was investigated. Mice were rendered monocytopenic by administration of etoposide, a drug that selectively depletes the monocyte/macrophage population and then injected with GBS (1 x 10(7) colony-forming units per mouse). Appearance of arthritis, mortality, GBS growth in the organs, and local and systemic cytokine production were examined. Etoposide-treated mice had a significantly less severe arthritis than control animals. Histopathological analysis of the joints confirmed clinical observations. Decreased joint levels of the proinflammatory cytokines interleukin 1 (IL-1) beta and IL-6 accompanied the less severe development of arthritis in monocytopenic mice. In contrast, mortality was increased in the etoposide-treated mice compared with controls. Monocytopenic mice exhibited elevated bacterial load in the blood and kidneys at all time points examined. These results indicate that lack of macrophages leads to less severe joint lesions, but also results in impaired clearance of bacteria, and consequent enhancement of mortality rates.     

Correlated fragile site expression allows the identification of candidate fragile genes involved in immunity and associated with carcinogenesis

Background  

Common fragile sites (cfs) are specific regions in the human genome that are particularly prone to genomic instability under conditions of replicative stress. Several investigations support the view that common fragile sites play a role in carcinogenesis. We discuss a genome-wide approach based on graph theory and Gene Ontology vocabulary for the functional characterization of common fragile sites and for the identification of genes that contribute to tumour cell biology.     

HOX11L1, a gene involved in peripheral nervous system development, maps to human chromosome 2p13.1-->p12 and mouse chromosome 6C3-D1.

HOX11L1 is a homeobox gene involved in peripheral nervous system development as confirmed by knockout mice exhibiting megacolon with enteric ganglia, a phenotype associated in human with Intestinal Neuronal Dysplasia (IND). Using FISH and radiation hybrids we have localized HOX11L1 to human chromosome 2p13.1-->p12, in a 14-cR interval between WI-5987 (D2S2088) and GCT1B4 (D2S2497), and confirmed the synteny between mouse 6C3-D1 and human 2p13.1-->p12 chromosomes by mapping an EST cDNA clone corresponding to mouse HOX11L1 (Tlx2).