Background Side effects of lifetime immunosuppression for cell transplants often outweigh the benefits, therefore, induction of transplant tolerance is needed. We have shown that cotransplantation with myeoid-derived suppressor cells (MDSC) effectively protect islet allografts from rejection without requirement of immunosuppression. This study was to investigate the underlying mechanisms. Methods MDSC were generated by addition of hepatic stellate cells (HpSC) from various stain mice into dendritic cell (DC) culture. The quality of MDSC was monitored by phenotype and function analyses. MDSC mixed with islet allografts were transplanted into diabetic recipients. T cell response was analyzed following transplant by flow and histochemical analyses, and compared to islet alone and islet/DC transplant groups. B7-H1 knockout mice were used to determine the role of B7-H1 on MDSC in regulation of T cell response. Results Cotransplantation with MDSC (not DC) effectively protected islet allografts without requirement of immunosuppression. This is associated with attenuation of CD8 T cells in the grafts and marked expansion of T regulatory (Treg) cells, which contributed to MDSC-induced T cell hyporesponsiveness. Antigen-specific Treg cells were prone to accumulate in lymphoid organs close to the grafts. Both in vitro and in vivo data demonstrated that B7-H1 was absolutely required for MDSC to exert immune regulatory activity and induction of Treg cells. Conclusion The described approach holds great clinical application potential, and may overcome the limitation of requiring chronic administration of immunosuppression in cell transplants. Understanding the underlying mechanisms will facilitate the development of this novel therapeutic strategy.

A small, uncooled plasma torch was developed and used in combination with a novel injector design to study ignition and flameholding in hydrogen-fueled supersonic flows. The plasma torch was operated with mixtures of hydrogen and argon at total flows of 4.7 x 10 3 to 3.30 x 10 4 seem. The fuel injector design consisted of five small upstream pilot fuel injectors, a rearward-facing step for recirculation, and three main fuel injectors downstream of the step. The plasma torch was located in the recirculation region and aU injection was perpendicular to the Mach 2 stream. The combustion tests were conducted in a direct-connect mode at simulated scramjet combustor conditions of Mach 2, total temperatures of 780-1560 K, and a static pressure of 101 kPa. Both semifreejet and ducted tests were conducted. The experimental results indicate that a low-power plasma torch operating on a 1:1 volumetric mixture of hydrogen and argon and located in the recirculation zone fueled by the upstream pilot fuel injectors is a good igniter for the flow conditions simulating a flight Mach number of 3.7 (T t , total temperature of the air = 780 K). The total temperature required to autoignite the hydrogen fuel for this injector geometry was 1470 K. The new injector configuration was shown to be a good flameholder over a wide range of total temperatures. Spectroscopic measurements were used to verify the presence of hydrogen atoms in the torch exhaust. Hydrogen atoms appear to be responsible for ignition at air total temperatures below 890 K. This observation is based on the results of the spectroscopic tests and the fact that a 100% argon plasma with the same power input did not ignite the flow at these temperatures.

Lipoblastoma and lipoblastomatosis are rare benign neoplasms of foetal white fat tissue that occur almost exclusively in infants and children. Two cases are reported and a review of the literature is given. An almost one-year-old girl and a full-term male infant were brought to our hospital with a solid mass in the right thigh. Nine months after total excision of the lipoblastoma, the little girl developed tumour recurrence, with unexpected histopathological maturation. In the case of the little boy, lipoblastomatosis with infiltration of the surrounding muscles, together with involvement of the sciatic and posterior femoral cutaneous nerves was found. Histologically, the tumour showed an unusual inflammatory reaction. The diagnosis of this tumour was made by the pathologist, but the histopathological picture bears a striking similarity to myxoid liposarcoma, and may be indistinguishable. Recent studies describe rearrangements of chromosome 8 q11-q13 region as a new discriminative marker that distinguishes lipoblastoma and lipoblastomatosis from myxoid liposarcoma.

Three different CVD SiC fibers were tested for bend stress relaxation (BSR) and tensile creep over a wide range of temperatures, times, and stresses. Primary creep was always observed, even for creep strains on the order of 2%. The BSR and tensile creep results were compared using simple linear viscoelastic principles. It was found that BSR results could predict the same time and temperature dependence as tensile creep; however, BSR‐predicted creep strains usually overestimated the magnitude of tensile creep strain. The time, temperature, and stress dependence were determined for all the fibers for the experimental conditions of this study. Some of the primary creep behavior can be explained by load‐sharing effects between the core and the CVD SiC substrate and some microstructural changes; however, the extent of primary creep cannot fully be accounted for from this work.

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