Orbital-Overlap control in the solid-state reactivity of beta-azido-propiophenones: selective formation of cis-azo-dimers.

Solid-state photolysis of 1a,b yields selectively cis-3a,b. X-ray analysis of 1a,b reveals the molecules adopt an extended structure and as such the crystal packing arrangement consists of planar, pi-stacked molecules. The shortest intermolecular distance between adjacent N-atoms is approximately 3.76 A and would lead to formation of trans-3a,b, whereas cis-3a,b is formed by dimerization between N-atoms that are approximately 3.9 A apart. We propose that the molecular orbital alignment of the adjacent nitrenes controls the solid-state reactivity.

FasL is important in costimulation blockade-resistant skin graft rejection.

BACKGROUND: Simultaneous blockade of the CD40 and CD28 costimulatory pathways is effective in prolonging allograft survival in murine and primate models. Recent data suggest that intact apoptotic pathways are crucial for the induction of hyporesponsiveness by costimulation blockade. We have studied the impact of fas/fasL signaling, an important T cell apoptotic pathway, on the effects of costimulation blockade. Methods. Wild type, lpr (fas deficient), and gld (fasL deficient), mice were used as donors and recipients in the murine skin graft model. Allograft survival was compared in untreated and costimulation blockade (500 microg anti-CD40L and 500 microg CTLA4-Ig, days 0, 2, 4, 6) treated recipients. In some recipients, CD4+ T cells were depleted using rat anti-murine CD4 (100 microg day -3, -2, -1, and weekly). RESULTS: gld mice treated with costimulation blockade enjoy a significantly greater increase in skin allograft survival than do wild-type mice. This effect is not replicated using lpr donors or recipients. Experiments in which CD4+ cells were depleted demonstrate that fasL is not necessary for CD8-mediated allograft rejection, and that depletion of CD4+ cells eliminates some of the survival advantage induced by costimulation blockade. CONCLUSIONS: FasL is not required for the establishment of costimulation blockade induced hyporesponsiveness, but rather appears to be required for normal costimulation blockade resistant rejection. Fas expression is not critical for costimulation blockade resistant rejection, suggesting that fasL may be interacting with other receptors. Further, it appears that CD4+ cells are important in the maintenance of allograft protection induced by costimulation blockade in this model.

Negative-pressure dressings in the treatment of hidradenitis suppurativa.

Negative-pressure dressings have been used in the treatment of a variety of open wounds, and as a bolster for skin grafts. The benefits of these dressings include increased oxygen tension in the wound, decreased bacterial counts, increased granulation formation, and the prevention of shear force on wounds. Also, by virtue of the diminished need for daily dressing changes, there are the additional advantages of enhancing patient comfort, decreasing nursing work, and diminished cost of wound care. Hidradenitis suppurativa (HS) is a chronic infection of the apocrine sweat glands. Treatment options range from oral isotretinoin to radical excision. Wound closure may be achieved by secondary intention, skin grafting, or flap closure. Complications may still arise and include disease progression and squamous cell carcinoma. Radical excision yields the best results in terms of disease eradication. The authors describe using the negative-pressure dressing in two cases of bilateral axillary HS to secure skin grafts firmly to the wound bed after radical excision of all involved tissues. Patient comfort and acceptance was high, and skin graft take was excellent. The dressings themselves are simple to apply and are highly effective.

Phlegmasia cerulea dolens of the upper extremity.

Phlegmasia cerulea dolens (PCD) is the term describing the painful venous congestion that results from near-total venous occlusion of a limb. It is unusual in the lower extremity but is decidedly rare in the upper extremity with only a handful of cases reported in the literature. PCD of the upper extremity usually occurs in patients with significant comorbid conditions such as severe cardiac failure or advanced malignancy. PCD of the upper extremity is associated with substantial morbidity and mortality. We present a case of upper extremity PCD in an elderly man with a complex medical history, complicated clinical course, and poor outcome that is typical for this rare disease.

Pregnancy as a tissue expander in the repair of a massive ventral hernia.

The use of tissue expanders has been described in numerous applications, including the closure of massive abdominal wall defects. The advantages of tissue expansion include providing adequate soft tissue for stable coverage of prosthetic material. In a subfascial plane, expanders can also expand muscle and fascia to allow total autologous repair of massive ventral hernias. These techniques for abdominal wall reconstruction are well established to cover viscera, to repair hernias, and to restore acceptable contour. The authors present the novel case of a woman with unstable skin graft coverage of a massive ventral hernia whose pregnancy was used as a surrogate intra-abdominal tissue expander to facilitate abdominal wall reconstruction.

The role of tissue expansion in abdominal wall reconstruction.

Abdominal wall reconstruction of ventral hernia defects with loss of visceral domain and inadequate soft-tissue coverage presents a surgical challenge. Four patients with large, skin grafted ventral hernia defects were treated by staged abdominal wall reconstruction. During the initial stage, tissue expanders were placed under the skin and subcutaneous tissue lateral to the defects. After adequate interval expansion, the second stage was performed. The expanders were removed, the visceral contents reduced easily, and the fascia reapproximated with polypropylene mesh. The expanded skin was closed easily over the fascial repair. All four patients were reconstructed successfully without complications. Tissue expansion can restore abdominal domain and allow soft-tissue closure in complicated ventral hernia defects.

Asialo GM1(+) CD8(+) T cells play a critical role in costimulation blockade-resistant allograft rejection.

Simultaneous blockade of the CD40 and CD28 costimulatory pathways is an effective treatment strategy to promote allograft acceptance but does not lead to indefinite allograft survival. The immune mechanisms responsible for costimulation-independent rejection are not defined. Here we have studied the rejection responses of murine C57BL/6 recipients, which we show to be relatively resistant to inhibition by combined CD40/CD28 blockade. We demonstrate that asialo GM1(+) CD8(+) cells play a critical role in this costimulation blockade-resistant rejection. These results provide new insights into the costimulatory requirements for T-cell subsets and demonstrate for the first time that combined blockade of the CD40 and CD28 pathways does not adequately inhibit CD8-mediated skin allograft rejection. Furthermore, we provide evidence that asialo GM1 is a potentially important therapeutic target for CD8-dependent immune responses.

Prolonged acceptance of concordant and discordant xenografts with combined CD40 and CD28 pathway blockade.

BACKGROUND: The prompt and vigorous immune response to xenogenic tissue remains a significant barrier to clinical xenotransplantation. Simultaneous blockade of the CD28 and CD40 costimulatory pathways has been shown to dramatically inhibit the immune response to alloantigen. METHODS: . In this study, we investigated the ability of simultaneous blockade of the CD28 and CD40 pathways to inhibit the immune response to xenoantigen in the rat-to-mouse and pig-to-mouse models. RESULTS: Simultaneous blockade of the CD28 and CD40 pathways produced marked inhibition of the cellular response to xenoantigen in vivo and produced long-term acceptance of xenogeneic cardiac and skin grafts (rat-to-mouse), and markedly suppressed an evoked antibody response to xenoantigen. In addition, this strategy significantly prolonged the survival of pig skin on recipient mice. CONCLUSIONS: Long-term hyporesponsiveness to xenoantigen across both a concordant and discordant species barrier, measured by the stringent criterion of skin grafting, can be achieved using a noncytoablative treatment regimen.

IFN-gamma is critical for long-term allograft survival induced by blocking the CD28 and CD40 ligand T cell costimulation pathways.

It is postulated that IFN-gamma production hinders long-term acceptance of transplanted organs. To test this hypothesis, we compared survival of skin and heart allografts in wild-type (IFN-gamma+/+) mice to that in IFN-gamma gene knockout (IFN-gamma-/-) mice. We found that perioperative blockade of the CD28 and/or CD40 ligand T cell costimulation pathways induces long-term skin and heart allograft survival in IFN-gamma+/+ recipients but fails to do so in IFN-gamma-/- mice or in wild-type mice treated with IFN-gamma-neutralizing Ab at the time of transplantation. In vitro studies showed that endogenously produced IFN-gamma down-regulates T cell proliferation and CTL generation in MLCs. These actions of IFN-gamma were not mediated by TNF-alpha production or Fas-Fas ligand interactions. In vivo studies revealed exaggerated expansion and, subsequently, impaired deletion of superantigen-reactive T lymphocytes in IFN-gamma-/- mice injected with staphylococcal enterotoxin B. Taken together, our findings indicate that IFN-gamma does not hinder but instead facilitates induction of long-term allograft survival possibly by limiting expansion of activated T cells.

Microchimerism and rejection in clinical transplantation.

BACKGROUND: Haemopoietic microchimerism has been identified in recipients of solid-organ transplants and is thought by some to be critical for the development and maintenance of immunological tolerance. The aim of this study was to correlate prospectively the persistence of donor cells with clinical outcome in recipients of kidney, kidney and pancreas, and liver transplants. METHODS: Persistence of donor cells in recipient peripheral blood was assessed at 3 days, and at 1, 3, 6, and 12 months after transplantation by a two-stage nested PCR technique to detect donor MHC HLA DR gene specifically. A pretransplant blood sample was collected from each patient to serve as an individual negative control. Seven liver, six kidney and pancreas, and 17 kidney patients were enrolled. 12 of the 17 kidney patients and all of the kidney and pancreas, and liver recipients were suitable for analysis. Exact matches for donors and recipients at the HLA DR loci (n = 1) or inability to obain primer pair specificity among similar HLA DR types (n = 4), meant that we were unable to analyse five patients. FINDINGS: Donor DNA was detected in 20 (80%) of 25, ten (40%) of 25, seven (30%) of 23, five (22%) of 23, and six (32%) of 19 recipients at 3 days, and 1, 3, 6 and 12 months post-transplant, respectively. Within individuals, the detection of donor DNA varied over time; only two patients had detectable donor DNA at all times. Analysis of the whole group of transplant patients showed a similar frequency and severity of rejection episodes in patients with and without microchimerism as defined by detectable donor DR genes. INTERPRETATION: These data suggest that a significant percentage of the recipients had persistent donor class II DNA in the peripheral circulation for at least 1 year after transplantation. We showed that a pretransplant blood sample is critical to avoid a false-positive result, and suggest that detectable chimerism may vary over time in individual patients. Therefore, analysis of microchimerism with a single, post-transplant analysis may not help in making clinical decisions for individual patients.

Long-term acceptance of skin and cardiac allografts after blocking CD40 and CD28 pathways.

The receptor-ligand pairs CD28-B7 and CD40-gp39 are essential for the initiation and amplification of T-cell-dependent immune responses. CD28-B7 interactions provide 'second signals' necessary for optimal T-cell activation and IL-2 production, whereas CD40-gp39 signals co-stimulate B-cell, macrophage, endothelial cell and T-cell activation. Nonetheless, blockade of either of these pathways alone is not sufficient to permit engraftment of highly immunogenic allografts. Here we report that simultaneous but not independent blockade of the CD28 and CD40 pathways effectively aborts T-cell clonal expansion in vitro and in vivo, promotes long-term survival of fully allogeneic skin grafts, and inhibits the development of chronic vascular rejection of primarily vascularized cardiac allografts. The requirement for simultaneous blockade of these pathways for effective inhibition of alloimmunity indicates that, although they are interrelated, the CD28 and CD40 pathways are critical independent regulators of T-cell-dependent immune responses.

CTLA4-Ig plus bone marrow induces long-term allograft survival and donor specific unresponsiveness in the murine model. Evidence for hematopoietic chimerism.

Allograft rejection is dependent on T cell activation, which requires both the engagement of the T cell receptor by antigen in the context of the MHC molecules and costimulatory signals delivered by cell surface molecules such as B7-CD28/CTLA4 pathway. CTLA4-Ig is a fusion protein that blocks this pathway and has previously been shown to prolong both allograft and xenograft survival. The current study demonstrates markedly prolonged murine cardiac allograft survival and specific prolongation of secondary skin grafts using a combination of CTLA4-Ig plus donor bone marrow. A role for hematopoietic chimerism in the establishment of CTLA4-Ig-induced transplantation tolerance was investigated using reverse transcriptase polymerase chain reaction analysis of recipient tissues. Expression of donor-specific MHC class II transcripts in both peripheral and lymphoid tissues was demonstrated at greater than 200 days after transplant. To investigate the functional significance of this observation, heart donors, and donor bone marrow were irradiated before transplantation in CTLA4-Ig-treated recipients. A reduction in allograft survival was associated with irradiation of both the donor heart and the bone marrow. These results suggest that there may be a donor-derived radiosensitive element that enhances allograft survival in this model. Reverse transcriptase polymerase chain reaction analysis of allografts of tolerant and control animals at days 5, 8, and 12 after transplantation failed to demonstrate a dramatic difference in the expression of interleukin (IL)-2, IL-4, IL-10, and interferon-gamma message. Cytotoxicity effector transcripts were largely intact in CTLA4-Ig + bone marrow-treated recipients as they showed no decrease in intragraft granzyme, perforin, Fas, or Fas ligand transcripts during thr first 8 days after transplant. These results imply that complex mechanisms may be important for the induction and maintenance of transplantation tolerance in the CTLA4-Ig plus bone marrow murine cardiac allograft model.

CD40-gp39 interactions play a critical role during allograft rejection. Suppression of allograft rejection by blockade of the CD40-gp39 pathway.

Studies in vivo have documented the importance of CD40-gp39 interactions in the development of T-dependent antibody responses to foreign and auto-antigens. In this report, we demonstrate that allograft rejection is also associated with strong induction of CD40 and gp39 transcripts. When treatment was initiated at the time of transplant, MR1, a mAb specific for gp39, induced markedly prolonged survival of fully disparate murine cardiac allografts in both naive and sensitized hosts. However, when therapy was delayed until postoperative day 5, anti-gp39 failed to prolong graft survival. Allografts from recipients treated with MR1 from the time of transplantation showed decreased expression of transcripts for the macrophage effector molecule, inducible nitric oxide synthase, but essentially unaltered expression of B7 molecules and T cell cytokine transcripts (interleukin [IL]-2, interferon-gamma, IL-10, and IL-4) relative to control allografts. In addition, alloantibody responses in the MR1-treated mice were profoundly inhibited. However, our studies using B cell-deficient mice indicated that the ability of MR1 to prolong allograft survival was not dependent on B cells. These data suggest that blockade of CD40-gp39 interactions may inhibit allograft rejection primarily by interfering with T cell help for effector functions, rather than by interference with T cell activation.

Ascariasis pneumonitis: a potentially fatal complication in smoke inhalation injury.

Ascaris pneumonitis in areas of endemic infestation is considered a benign condition. Smoke inhalation with any burn injury can be potentially fatal. A heavy infestation of Ascaris could further exacerbate the smoke-induced lung injury. After ingested eggs hatch in the small intestine, the larvae penetrate the mucosa and invade the blood stream and are then carried to the lungs. The larvae break out into the aveolar spaces as they are too large to cross the capillary bed and are carried up the bronchial tree and eventually swallowed. This study describes three cases of Ascaris infection in thermally injured children. While the burns were < 30 per cent total body surface area, two patients who were injured in the same fire had a further complication of smoke inhalation which necessitated sophisticated therapy in order to promote survival. All patients were treated initially with Vermox. The one patient without smoke inhalation did not develop ascariasis pneumonitis even with positive stool samples and was discharged with no complications, whereas the two with smoke inhalation developed severe pneumonitis. One patient was placed on ECMO and did not receive a full course of the Vermox treatment. This patient died after several weeks of ECMO treatment. The third patient received a full course of Vermox, slowly recovered, and went home. Supportive therapy only is recommended during the lung migration phase of the Ascaris lifecycle. We feel that continuation of chemotherapy (Vermox) would have been beneficial in the fatal case based on the survival of the second patient.(ABSTRACT TRUNCATED AT 250 WORDS)