Single-material semiconductor hyperbolic metamaterials.

Layered semiconductor hyperbolic metamaterials for the mid-infrared are grown by molecular beam epitaxy using a single material system, doped and undoped InAs. The onset wavelength for metamaterial behavior can be tuned from 5.8µm to beyond 10µm, while the fill factor ranges from 0.25 to 0.75, resulting in designer optical behavior. The reflection and transmission behavior were studied by Fourier transform spectroscopy and modeled using effective medium theory. We also conducted a geometric optics experiment to demonstrate negative refraction of our materials.

Changes in the pattern of TCR V beta repertoire expression after bone marrow transplant is linked to the HLA haplotype in humans.

Neutrophil, monocyte, natural killer- and B-cell number and function are rapidly restored after bone marrow transplant (BMT), whereas T-cell reconstitution is often quite delayed. Our hypothesis was that V beta T-cell receptor (TCR) repertoire diversity among recipients of allogeneic BMT is influenced by the expression of major and minor HLA antigens in the host. The study population comprised unmanipulated and CD34(+)-selected allogeneic bone marrow grafts, autologous peripheral blood stem cell transplants and recipients of volunteer unrelated donor (VUD) bone marrow transplants. Using flow cytometry, the relative frequencies of 18 V beta TCR families were determined and ranked for each time point studied. Comparisons and correlations were made between paired blood samples obtained within a single patient over time, and between donors and their recipients. The pattern of the V beta TCR repertoire from allogeneic recipients and their HLA-matched donors was very similar, with a correlation coefficient (CC) of 0.59. This similarity was not as marked in VUD pairs (CC = 0.32). By 3 months after transplant, the pattern of the V beta TCR repertoire in recipients of HLA-matched sibling transplants was more similar to the pattern seen in pretransplant recipients than to the donor pattern (CC = 0.40 vs. 0.31). Our data suggest that both major and minor HLA antigens influence V beta TCR repertoire diversity and reconstitution after BMT.

Lymphoid reconstitution after autologous PBSC transplantation with FACS-sorted CD34+ hematopoietic progenitors.

T-cell and B-cell reconstitution was studied in nine patients who received fluorescence activated cell sorter (FACS)-sorted autologous CD34+ hematopoietic progenitor cells (HPC). The mean numbers of T cells (CD3+), B cells (CD19+) and CD34+ HPC administered to each patient were .004, .002, and 1.8 x 10(6) cells/kg, respectively. After high-dose myeloablative chemotherapy (busulfan, cyclophosphamide, etoposide) CD34+) HPC were infused and lymphoid reconstitution was monitored using flow cytometry and reverse transcriptase-polymerase chain reaction (RT-PCR) amplification of VDJ T-cell receptor (TcR) sequences. Restoration of normal numbers of peripheral blood T cells and B cells among recipients of FACS-sorted CD34+ HPC was delayed compared to recipients of non-T-cell-depleted PBSC autografts. In both patient groups, the circulating T cells were primarily CD4-, CD8+, alphabeta TcR+, and CD45RO+, CD45RA- during the first 2 months after transplant. Subsequent increases in the frequency of CD45RA+ CD45RO- T cells occurred at 2 to 3 months after transplant, suggesting maturation of CD34+ hematopoietic progenitors to "naive" T cells. Analysis of the TcR repertoire after hematopoietic reconstitution demonstrated decreased diversity of Vbeta TcR expression associated with global decreases in the absolute number of total peripheral blood T cells and most Vbeta TcR+ subsets. Three of nine recipients of FACS-sorted CD34+ HPC demonstrated significant increases in the percentage of gammadelta+ peripheral T cells and CD5+ B cells at 3 to 9 weeks after transplantation, and all patients had transient oligoclonal expansions of T cells expressing specific Vbeta TcR. Transplantation with highly purified CD34+ HPC results in reduced diversity of the peripheral T-cell repertoire during the early post-transplant period compared with patients receiving unmanipulated or MoAb-depleted transplants.

Dexamethasone and hydrocortisone enhance the in vitro migration of prethymic stem cells to thymus supernatant.

The migration of prethymic stem cells from the bone marrow to thymus supernatant was examined in a blind well migration assay following treatment with glucocorticoids (GCS). To study the in vivo effects of GCS, time release pellets containing dexamethasone (DEX) were implanted subcutaneously in young adult CBA/J mice for 7, 14 and 21 days. After seven and 21 days of DEX treatment, enhanced migration of bone marrow lymphoid cells to thymus supernatant occurred. To study the in vitro effects of GCS on prethymic stem cell migration, bone marrow cells were incubated for one or six hours in media containing dexamethasone (DEX), hydrocortisone (HCS), or medium alone. After a six-hour incubation with GCS, significantly more bone marrow cells migrated toward thymus supernatant in vitro than bone marrow cells incubated in medium alone. The enhanced migration of cells to thymus supernatant seen in this assay may reflect a feedback mechanism whereby bone marrow cell migration is enhanced to restore the thymic lymphocyte reserves depleted following treatment with GCS.

Restraint and sound stress reduce the in vitro migration of prethymic stem cells to thymus supernatant.

Murine bone marrow cells were examined in an in vitro assay to determine whether stress modulates the migration of prethymic stem cells to thymus supernatant. Adult CBA/J mice were either restraint or sound stressed for two hours daily for five days. Bone marrow cells were removed and migrated toward newborn thymus supernatant in an in vitro migration assay in blind well chambers. Bone marrow cells from animals which had been stressed for five days showed a significant decrease in the percent migration to thymus supernatant when compared to bone marrow cells from age-matched control mice. This suggests that either a smaller proportion of precursor cells are available in the bone marrow for migration to the thymus or the number of cells remains the same but these cells are less responsive to chemoattractive factors in the supernatant, thus causing them to migrate at a decreased rate.