Anisotropic origin of transform faults

Transform faults appear in the process of stretching during freezing of the surface films on liquid wax. These films are composed of a warp yarn of wax fibers with optical anisotropy. This fabric is absent in materials that fail to produce transform faults. The mechanical anisotropy of these wax films (with high tensile strength and low shear strength in the direction of spreading) is responsible for the initiation of the transform faults. It is suggested that the anisotropy of the ocean upper mantle recorded seismically may likewise be responsible for the creation of the ridge-ridge transform faults in the oceans.     

Canine Haematopoietic Chimerism Analyses by Semiquantitative Fluorescence Detection of Variable Number of Tandem Repeat Polymorphism

Canine models are successfully applied to the study of haematopoietic stem cell transplantation (HSCT). Monitoring of haematopoietic donor/recipient chimerism is of major significance in detecting and quantifying engraftment or graft rejection of the donor-derived haematopoietic cells after transplantation. Radioactive analyses of polymorphic microsatellite markers are commonly used for chimerism analyses. We describe an improved, non-isotopic method that is based on the analysis of microsatellite markers in donor and recipient cells using capillary electrophoresis and fluorescence detection. Artificial mixtures of donor and recipient DNA that were generated from peripheral blood mononuclear cells from dog leukocyte antigen-identical siblings were used to analyse the sensitivity of the assay. DNA from dogs that had received HSCT were also analysed in order to demonstrate the feasibility of the method in vivo. For chimerism analyses, six different microsatellite loci were systematically amplified using fluorescent PCR primer. The fluorescent polymerase chain reaction products were separated by capillary electrophoresis using POP4 on a 310 ABI Prism Genetic Analyzer. After electrophoresis, fluorescence signals were automatically sized and quantified using GeneScan software. The method described provides an accurate assessment of haematopoietic chimerism in the canine model with significantly reduced hands-on time compared to conventional gel electrophoresis.     

Upfront denileukin diftitox as in vivo regulatory T-cell depletion in order to enhance vaccination effects in a canine allogeneic hematopoietic stem cell transplantation model

Denileukin Diftitox (ONTAK^®, DAB₃₈₉ IL-2) is a recombinant DNA-derived fusion protein depleting cells that express high-affinity IL-2 receptor. Important cell targets are CD4⁺CD25⁺Foxp3⁺ regulatory T cells (T_reg). Elimination of immunosuppressive T_reg by Denileukin Diftitox may provide a way to modulate immune tolerance following stem cell transplantation. Here, we combined T_reg depletion with a vaccination approach to induce donor-specific immune reactions. To investigate this approach we chose the mixed chimerism canine stem cell transplantation model which represents a high state of tolerance between two hematopoietic systems. The aim was therefore to induce a graft versus hematopoiesis effect thereby converting mixed to full donor chimerism. Dog leukocyte antigen identical siblings that had developed a stable mixed chimerism after non-myeloablative stem cell transplantation received a single dose of Denileukin Diftitox (18 μg/kg, i.v.) followed by several cell-lysate vaccinations. Host peripheral blood mononuclear cell lysates combined with CpG-ODN, and Montanide^® ISA 51 were locally applied. In vitro studies demonstrated that canine T_reg are a target of Denileukin Diftitox. The suppression of T-cell proliferation by T_reg was abolished by addition of Denileukin Diftitox (10 nM). An increase of proliferation of median 300% (range: 200%–425%) was observed. No change in donor chimerism was observed after administration of Denileukin Diftitox and vaccination. This study highlights that application of Denileukin Diftitox resulted in a depletion of T_reg followed by an increase of immune response in vitro. This effect could not be confirmed in vivo even if the immune system was stimulated by vaccinations.     

Survival of pseudorabies virus in the presence of selected diluents and fomites.

Because of the importance of environmental survival of pseudorabies virus to proposals to eradicate the virus from swine in the United States, survival of the virus was studied in various diluents and on combinations of diluents and solid fomites at 25 C. Suspensions of the virus in phosphate-buffered saline and saline G solutions remained infectious for at least 10 days. Infectivity of other virus/diluent suspensions decreased to less than 10 plaque-forming units/ml in 14 days (swine urine), 7 days (well water), 4 days (swine saliva), 2 days (lagoon water and swine nasal washings), and 1 day (swine pit effluent, chlorinated water, and bile). Suspensions of pseudorabies virus in saline G solution and on the solid fomites, whole corn, and steel remained infectious for at least 7 days. Infectivity of other virus/diluent/fomite combinations decreased to less than 10 plaque-forming units/ml in 7 days. The role of the fomites as vehicles for transmission of infection is discussed.