A humanized model for multiple sclerosis using HLA-DR2 and a human T-cell receptor

Multiple sclerosis (MS) is a complex chronic neurologic disease with a suspected autoimmune pathogenesis. Although there is evidence that the development of MS is determined by both environmental influences and genes, these factors are largely undefined, except for major histocompatibility (MHC) genes. Linkage analyses and association studies have shown that susceptibility to MS is associated with genes in the human histocompatibility leukocyte antigens (HLA) class II region, but the contribution of these genes to MS disease development less compared with their contribution to disorders such as insulin-dependent diabetes mellitus. Due to the strong linkage disequilibrium in the MHC class II region, it has not been possible to determine which gene(s) is responsible for the genetic predisposition. In transgenic mice, we have expressed three human components involved in T-cell recognition of an MS-relevant autoantigen presented by the HLA-DR2 molecule: DRA*0101/DRB1*1501 (HLA-DR2), an MHC class II candidate MS susceptibility genes found in individuals of European descent; a T-cell receptor (TCR) from an MS-patient-derived T-cell clone specific for the HLA-DR2 bound immunodominant myelin basic protein (MBP) 4102 peptide; and the human CD4 coreceptor. The amino acid sequence of the MBP 84-102 peptide is the same in both human and mouse MBP. Following administration of the MBP peptide, together with adjuvant and pertussis toxin, transgenic mice developed focal CNS inflammation and demyelination that led to clinical manifestations and disease courses resembling those seen in MS. Spontaneous disease was observed in 4% of mice. When DR2 and TCR double-transgenic mice were backcrossed twice to Rag2 (for recombination-activating gene 2)-deficient mice, the incidence of spontaneous disease increased, demonstrating that T cells specific for the HLA-DR2 bound MBP peptide are sufficient and necessary for development of disease. Our study provides evidence that HLA-DR2 can mediate both induced and spontaneous disease resembling MS by presenting an MBP self-peptide to T cells.     

Dissociation of dopamine release in the nucleus accumbens from intracranial self-stimulation

Mesolimbic dopamine-releasing neurons appear to be important in the brain reward system. One behavioural paradigm that supports this hypothesis is intracranial self-stimulation (ICS), during which animals repeatedly press a lever to stimulate their own dopamine-releasing neurons electrically. Here we study dopamine release from dopamine terminals in the nucleus accumbens core and shell in the brain by using rapid-responding voltammetric microsensors during electrical stimulation of dopamine cell bodies in the ventral tegmental area/substantia nigra brain regions. In rats in which stimulating electrode placement failed to elicit dopamine release in the nucleus accumbens, ICS behaviour was not learned. In contrast, ICS was acquired when stimulus trains evoked extracellular dopamine in either the core or the shell of the nucleus accumbens. In animals that could learn ICS, experimenter-delivered stimulation always elicited dopamine release. In contrast, extracellular dopamine was rarely observed during ICS itself. Thus, although activation of mesolimbic dopamine-releasing neurons seems to be a necessary condition for ICS, evoked dopamine release is actually diminished during ICS. Dopamine may therefore be a neural substrate for novelty or reward expectation rather than reward itself.     

Cytotoxic T-cell immunity to virus-infected non-haematopoietic cells requires presentation of exogenous antigen

Cytotoxic T lymphocytes (CTLs) are thought to detect viral infections by monitoring the surface of all cells for the presence of viral peptides bound to major histocompatibility complex (MHC) class I molecules. In most cells, peptides presented by MHC class I molecules are derived exclusively from proteins synthesized by the antigen-bearing cells. Macrophages and dendritic cells also have an alternative MHC class I pathway that can present peptides derived from extracellular antigens; however, the physiological role of this process is unclear. Here we show that virally infected non-haematopoietic cells are unable to stimulate primary CTL-mediated immunity directly. Instead, bone-marrow-derived cells are required as antigen-presenting cells (APCs) to initiate anti-viral CTL responses. In these APCs, the alternative (exogenous) MHC class I pathway is the obligatory mechanism for the initiation of CTL responses to viruses that infect only non-haematopoietic cells.     

Structural basis for self-association and receptor recognition of human TRAF2

Tumour necrosis factor (TNF)-receptor-associated factors (TRAFs) form a family of cytoplasmic adapter proteins that mediate signal transduction from many members of the TNF-receptor superfamily and the interleukin-1 receptor. They are important in the regulation of cell survival and cell death. The carboxy-terminal region of TRAFs (the TRAF domain) is required for self-association and interaction with receptors. The domain contains a predicted coiled-coil region that is followed by a highly conserved TRAF-C domain. Here we report the crystal structure of the TRAF domain of human TRAF2, both alone and in complex with a peptide from TNF receptor-2 (TNF-R2). The structures reveal a trimeric self-association of the TRAF domain, which we confirm by studies in solution. The TRAF-C domain forms a new, eight-stranded antiparallel beta-sandwich structure. The TNF-R2 peptide binds to a conserved shallow surface depression on one TRAF-C domain and does not contact the other protomers of the trimer. The nature of the interaction indicates that an SXXE motif may be a TRAF2-binding consensus sequence. The trimeric structure of the TRAF domain provides an avidity-based explanation for the dependence of TRAF recruitment on the oligomerization of the receptors by their trimeric extracellular ligands.     

Effect of actinomycin D on Trypanosoma cruzi

Viable metacyclic forms of T. cruzi, Y strain, treated with an adequate dose of actinomycin D (50 micrograms Act-D/ml/10(7) parasites/ml for 72 h at 28 degrees C) showed the following properties: 1) they lost their ability to replicate in culture medium, in blood and in tissues of normal mice and were no longer able to incorporate tritiated thymidine; 2) they could not penetrate into Vero cells and could not replicate inside normal macrophages; 3) they retained their immunogenicity and the ability to protect mice against a virulent infection; 4) they did not induce histological lesions as described in chronic experimental Chagas' disease.     

Wireless Location Determination for Mobile Objects Based on GSM in Intelligent Transportation Systems

1 .INTRODUCTIONTheabilityofpositioningmobileobjects (MOs) ,in cludingvehiclesandtravelersholdingmobiletermi nals,isafundamentalfunctionforsomeITSsubsys tems,suchasemergencyrescue,securitysystem ,au tomaticnavigationsystem ,andtrafficinducementsystem[1 ] .Atpresent,therearethreedominatingtypes[2 ]ofwirelesspositioningtechnologies,i.e.positioningbasedonsatellites,positioningbasedondedicatedcommunicationsystemsandpositioningbasedonpub liclandwirelesstelecommunicationsystems (PLMTS) ,respe…     

Alopecia induced in young mice by exposure to excess dietary zinc

Summary Second generation mice were exposed to normal (50 ppm, Group I) or excess (2000 ppm, Group II) zinc in the maternal diet during gestation and lactation, then weaned and continued on the mother's diet until sacrifice at 8 weeks. Tibia zinc reflected dietary intake. Group II had reduced plasma copper, body weight, and hematocrit; the second coat of hair appeared late and was lighter in color than Group I, possibly as an effect of copper and pigmentation development and hair growth.     

Re-routing of a secretory protein by fusion with human growth hormone sequences

Cells with electron-dense secretory vesicles use them to store only specialized secretory products such as peptide hormones; other types of secreted proteins are externalized by an alternative, constitutive route. One possible mechanism for such segregation is that proteins destined for dense secretory vesicles contain unique 'sorting domains' that allow for selective targeting. Here, we set out to determine whether a constitutively secreted protein could be diverted to the dense secretory vesicles by attachment to a peptide hormone sequence. We made use of the ability of the mouse pituitary tumour cell, AtT-20, to correctly sort exogenous secretory proteins introduced into them by DNA transfection. We constructed a plasmid encoding a hybrid protein in which a constitutively secreted viral protein was fused to the carboxy terminus of human growth hormone (hGH). Cells expressing the hybrid protein were found to target it to dense secretory vesicles with an efficiency close to that observed for the parental hGH. These results support the hypothesis that sorting domains on peptide hormones direct their packaging into dense secretory vesicles. The results also suggest that proteins secreted by the constitutive pathway either do not contain any sorting domain, or their sorting signals can be overridden by those which direct peptide hormones.