Core-shell nanoparticle arrays double the strength of steel.

Manipulating structure, defects and composition of a material at the atomic scale for enhancing its physical or mechanical properties is referred to as nanostructuring. Here, by combining advanced microscopy techniques, we unveil how formation of highly regular nano-arrays of nanoparticles doubles the strength of an Fe-based alloy, doped with Ti, Mo, and V, from 500 MPa to 1 GPa, upon prolonged heat treatment. The nanoparticles form at moving heterophase interfaces during cooling from the high-temperature face-centered cubic austenite to the body-centered cubic ferrite phase. We observe MoC and TiC nanoparticles at early precipitation stages as well as core-shell nanoparticles with a Ti-C rich core and a Mo-V rich shell at later precipitation stages. The core-shell structure hampers particle coarsening, enhancing the material's strength. Designing such highly organized metallic core-shell nanoparticle arrays provides a new pathway for developing a wide range of stable nano-architectured engineering metallic alloys with drastically enhanced properties.

Prolongation of the rat composite tissue allograft survival by the combination of tolerogenic immature dendritic cells and short-term treatment with FK506.

OBJECTIVE: Prevention of rejection in composite tissue allotransplantation without continuous immunosuppression is of paramount importance in the field of transplantation. Recently dendritic cells (DCs) have gained considerable attention as antigen-presenting cells that are also capable of tolerance induction. This study assessed the effect of interleukin (IL)-10-supplemented, alloantigen-pulsed immature tolerogenic DC to increase survival of orthotopic hind limb transplantations in rats. MATERIALS AND METHODS: Hind limbs from Sprague-Dawley (SD) hosts were transplanted to Fischer 344 (F344) rats. Peripheral blood mononuclear cells (PBMC) isolated from F344 were cultured to generate immature DCs (imDCs); IL-10 was added for tolerogenic DC induction. Flow cytometric analysis were performed to characterize the DC phenotype. IL-10-imDCs cocultured with donor mononuclear cells for 24 hours were reinjected into recipients subcutaneously 1 day before transplantation. Recipient animals were divided into 4 groups, each comprising 6 rats (n = 6): group I (untreated controls), group II (IL-10-imDCs alone), group III (FK-506 [Tacrolimus, 2 mg/kg] for 2 weeks postoperative), and group IV (recipient origin IL-10-imDCs combined with FK-506 for 2 weeks postoperative). Observation of graft appearance, cytokine production assays, and confocal immunofluorescence were performed at postoperative 1 week. RESULTS: The combination of IL-10-treated imDCs and FK-506 produced a significantly prolonged median allograft survival (46.7 days) compared with groups I (4.7), II (5.3), or III (26.3). Splenocytes isolated from rats treated with IL-10-imDCs plus and FK-506 produced significant amounts of IL-10 and IL-4 cytokines upon alloantigen stimulation, as confirmed using ELISPOT and ELISA. CONCLUSIONS: We demonstrated that IL-10-treated imDCs induced T-cell hyporesponsiveness, skewing the immune response to Th2 elements, resulting in long-term survival of composite tissue allografts.

Porcine islet adaptation to metabolic need of monkeys in pig-to-monkey intraportal islet xenotransplantation.

BACKGROUND: Physiologic regulation of glucose metabolism is different between donor and recipient of xenogeneic pancreatic islet transplantation. We sought to assess whether the capacity of donor islets to adapt to recipient metabolic requirements should be considered in determining the success of pancreatic islet xenotransplantation. METHODS: Rhesus macaque hosts rendered diabetic by streptozotocin were transplanted with porcine islets into the liver. Porcine c-peptide and insulin levels as well as intravenous glucose tolerance test (IVGTT) were measured at intervals. RESULTS: At 2 months after islet transplantation, glucose responses on IVGTT showed a normoglycemic pattern. There was a 2.48 fold increase in C-peptide level during the initial 15 minutes of IVGTT in normal monkeys: from 3.122 ng/mL at baseline to 7.728 ng/mL at 15 minutes. Monkeys transplanted with porcine islets showed 2.38- and 2.45-folds the initial increases in C-peptide on IVGTT at 2 and 4 months after transplantation, respectively. Histopathologic evaluation identified the host endothelial cells having well lined the vessels of the porcine islets in the monkey liver. CONCLUSIONS: The glucose response on IVGTT of porcine islets engrafted in the monkey liver resembled the normal monkey pattern rather than that of pigs. The presence of monkey endothelial cells suggested that porcine islets were well adapted to the local environment of the recipient.

Co-transplantation of bone marrow-derived endothelial progenitor cells improves revascularization and organization in islet grafts.

Bone marrow-derived early endothelial progenitor cells (BM-EPCs) are a clinical tool for enhancing revascularization. However, the therapeutic efficacy of co-transplantation of BM-EPC with islets has not been investigated. In this study, marginal mass islets were co-transplanted with or without BM-EPCs under the kidney capsules of syngeneic streptozotocin-induced diabetic mice. Using green fluorescent protein transgenic (GFP-Tg) mice as BM-EPC and islet donors or recipients, the role of EPCs in revascularization was assessed for graft morphology, vascular density and fate of EPCs by immunohistochemistry. Islet-EPC co-transplantation improved the outcome of islet transplantation as measured by glucose tolerance, serum insulin level and diabetes reversal rate, compared with transplantation of islets alone. Between groups, the morphology of islet grafts showed significant differences in size and composition of grafted endocrine tissues. Significantly more vessel density derived from donors and recipients was detected with islet-EPC co-transplantation. Abundant GFP-Tg mice-derived BM-EPCs (GFP-EPCs) were observed in or around islet grafts and incorporated into CD31-positive capillaries. Remaining GFP-EPCs expressed VEGF. In conclusion, co-transplantation of islets with BM-EPCs could improve the outcome of marginal mass islet transplantation by promoting revascularization and preserving islet morphology.

Combined nano-SIMS/AFM/EBSD analysis and atom probe tomography, of carbon distribution in austenite/ε-martensite high-Mn steels.

We introduce a new experimental approach for the identification of the atomistic position of interstitial carbon in a high-Mn binary alloy consisting of austenite and ε-martensite. Using combined nano-beam secondary ion mass spectroscopy, atomic force microscopy and electron backscatter diffraction analyses, we clearly observe carbon partitioning to austenite. Nano-beam secondary ion mass spectroscopy and atom probe tomography studies also reveal carbon trapping at crystal imperfections as identified by transmission electron microscopy. Three main trapping sites can be distinguished: phase boundaries between austenite and ε-martensite, stacking faults in austenite, and prior austenite grain boundaries. Our findings suggest that segregation and/or partitioning of carbon can contribute to the austenite-to-martensite transformation of the investigated alloy.

Acute necrotic stomatitis (noma) associated with methicillin-resistant Staphylococcus aureus infection in a newly acquired rhesus macaque (Macaca mulatta).

BACKGROUND: A newly acquired rhesus macaque was suffering from rapid destruction of the left cheek caused by necrotizing stomatitis. METHODS: To restore reconstructive surgery and intensive care with antibiotics, wound protection, wound healing agents, and debridement were applied. RESULTS: Staphylococcus aureus and Enterococcus faecalis were isolated from the culture of the lesion, and the antibiotic susceptibility test revealed methicillin-resistant Staphylococcus aureus infection. Vancomycin and ampicillin-sulbactam effectively treated the bacterial infections, and reconstructive surgery was performed once the infection was cleared. Topical application of recombinant human epidermal growth factor (rhEGF) was useful to treat exposed wound of the noma lesion. CONCLUSIONS: Simian noma associated with methicillin-resistant Staphylococcus aureus (MRSA) had not previously been reported in non-human primates. Although noma associated with MRSA is hard to cure because of its rapid and destructive progress, the aggressive therapy used in this study led to the successful resolution of an acute necrotic stomatitis lesion in a rhesus macaque.

Infection of porcine cells with human herpesviruses.

Porcine organs are valuable candidate materials for xenotransplantation to humans. Long-term maintenance of well functioning transplants is a prerequisite for success. Transplanted organs may be damaged by immune reactions or by infectious agents in hosts. Human herpesviruses (HHVs) establish life-long latency in humans after a primary infection. They can be reactivated with various stimuli, including immunosuppression. This study was performed to verify the infectivity of some HHVs toward porcine cells. PK-15 cells infected with HHV-1 and HHV-2 showed cytopathology from 1 day after infection. Immunofluorescent (IF) staining of HHV-1- and HHV-2-infected PK-15 cells with respective antibodies demonstrated the expression of the respective viral antigens. Permissiveness of PK-15 to HHV-1 and -2 was confirmed by an infection test on Vero cells. Islet cells infected with HHV-5 showed no gross morphologic changes during the experimental course. A limited portion of islet cells reacted only to anti-IE1 and anti-IE2, but not to anti-UL44 or anti-gB antibody by IF staining, whereas a small portion of endothelial cells reacted to anti-IEs and anti-UL44, but not to anti-gB antibody. HHV-1 and -2 can permissively infect porcine cells, but HHV-5 infects a small proportion of cells with limited viral protein expression. HHV-4 could not transform peripheral blood mononuclear cells from miniature pigs. Collectively, because some HHVs can infect and damage porcine cells or impair their functions, HHVs should be cautiously monitored and controlled in humans when porcine cells or organs are transplanted to human beings.

Investigation of blood typing method for seoul National University miniature pig.

Pig blood group antigens may be present on grafted tissue as 16 isoforms, including the major one, A substrance. Seoul National University (SNU) miniature pigs and domestic pigs were used in this study. Polymerase chain reaction (PCR) was performed for the erythrocyte antigen A (EAA) gene, and reverse transcriptase-PCR for pig A transferase fucosyl transferase (FUT) 1 and FUT-2. The hemagglutination test was performed with murine monoclonal anti-A and anti-B antibodies (mAb), and immunohistochemistry with anti-human blood antigen mAb. SNU miniature and domestic pigs showed blood groups A and O. Blood group A SNU miniature pigs expressed either EAA(AA) or EAA(AO) and either S(SS) or S(SO); blood group O miniature pigs expressed EAA(OO) and S(SS) or S(SO), and there was no A(weak). Additionally, blood group A could be divided into blood group A(clotting) and blood group A(not clotting) in hemagglutination tests. Pig A substance was expressed in the lung and kidney in blood group A pigs, but we could not detect pig A substance expression in the lung, kidney, and heart of blood group O pigs or the heart of blood group A pigs. In conclusion, we suggest that blood typing of SNU miniature pigs can be easily performed using immunohistochemistry, PCR, and/or RT-PCR. Molecular-based AO typing described in this study may be useful to select SNU miniature pigs bearing a specific blood group.

Molecular cloning and expression analysis of the pig small ubiquitin-like modifier (SUMO) gene family.

Small ubiquitin-like modifiers (SUMOs) are structurally related to ubiquitin and are ligated to lysine residues within sumoylation target proteins. Currently, a growing body of evidence shows that the SUMO family has evolved as an important modifier of many proteins in a variety of cellular pathways. In this study, we have cloned cDNA encoding for three different pig SUMO isoforms. The full-length cDNA encoding for pig Sumo1, Sumo2 and Sumo4 consists of 306, 288 and 288 nucleotide base pairs of the open reading frame, respectively, and the putative amino acid sequences of pig Sumo1, Sumo2 and Sumo4 are composed of 101, 95 and 95 peptides, respectively. The structures of pig SUMOs are evolutionally well conserved, and their expression has been detected in a broad range of tissues. We also determined that all pig SUMOs are localized within the nucleus. However, the different tissue expression observed in individual pig SUMOs may show the divergent or specialized role of each of the pig SUMO isoforms. Future studies will focus on the identification of targets for sumoylation by different pig SUMO isoforms and the analysis of the functional consequences of sumoylation during the course of infectious diseases in pigs.