Respiratory symptoms and bronchoalveolar lavage abnormalities in molybdenum exposed workers.

STUDY OBJECTIVES: To detect an adverse effect of chronic inhalative molybdenum trioxide (MoO3) exposure in a group of symptomatic MoO3 exposed workers. PARTICIPANTS: 43 inhalatively MoO3 exposed workers of a metal plant and 23 non-exposed controls were included in this study. Among the workers, 33 suffered from respiratory symptoms while 10 individuals were asymptomatic. INTERVENTIONS: Chest x-ray, spirometry and bronchoalveolar lavage (BAL) were performed using standard equipment. MEASUREMENTS AND RESULTS: Neither symptomatic nor asymptomatic MoO3 exposed workers showed firm radiological signs of interstitial lung disease. In lung function testing, symptomatic MoO3 exposed workers did not differ from their asymptomatic colleagues. Employees of the metal plant had a higher percentage of predicted forced expiratory volume in 1 second (FEV1 %) and a higher percentage of predicted forced vital capacity (FVC %) than controls (p<0.05). In BAL cytology, symptomatic MoO3 exposed workers showed higher percentage counts of lymphocytes (p < 0.001) and neutrophils (p < 0.01), and higher T4/T8 ratios (p < 0.01) than asymptomatic MoO3 exposed workers. Furthermore symptomatic workers showed higher percentage counts of lymphocytes (p < 0.05) and neutrophils (p < 0.05) than individuals of the control group. CONCLUSION: The results of BAL cytology in symptomatic workers may be interpreted as a MoO3 induced subclinical alveolitis. This may indicate an adverse effect of chronic inhalative MoO3 exposure. It remains unclear whether symptomatic MoO3 exposed workers are at risk for the development of an interstitial lung disease in the future.

Vascular endothelium does not activate CD4+ direct allorecognition in graft rejection.

Expression of MHC class II by donor-derived APCs has been shown to be important for allograft rejection. It remains controversial, however, whether nonhemopoietic cells, such as vascular endothelium, possess Ag-presenting capacity to activate alloreactive CD4(+) T lymphocytes. This issue is important in transplantation, because, unlike hemopoietic APCs, allogeneic vascular endothelium remains present for the life of the organ. In this study we report that cytokine-activated vascular endothelial cells are poor APCs for allogeneic CD4(+) T lymphocytes in vitro and in vivo despite surface expression of MHC class II. Our in vitro observations were extended to an in vivo model of allograft rejection. We have separated the allostimulatory capacity of endothelium from that of hemopoietic APCs by using bone marrow chimeras. Hearts that express MHC class II on hemopoietic APCs are acutely rejected in a mean of 7 days regardless of the expression of MHC class II on graft endothelium. Alternatively, hearts that lack MHC class II on hemopoietic APCs are acutely rejected at a significantly delayed tempo regardless of the expression of MHC class II on graft endothelium. Our data suggest that vascular endothelium does not play an important role in CD4(+) direct allorecognition and thus does not contribute to the vigor of acute rejection.

Fetal liver as a source of autologous progenitor cells for perinatal tissue engineering.

Mesenchymal progenitor cells, isolated from adult bone marrow, have been shown to have utility for autologous tissue engineering. The possibility of isolating from the fetal hematopoietic system a cell population with similar potential, which could be used for autologous reconstruction of prenatally diagnosed congenital anomalies, has not been explored to date. Liver stromal cells isolated from a portion of the right lateral hepatic lobe of midgestation fetal lambs were expanded in vitro. Passage 1 cells displayed a uniform fibroblast-like morphology but could be induced to differentiate into skeletal muscle, adipocytes, chondrocytes, and endothelial cells by selective medium supplementation. By manipulating the extracellular matrix in vitro, spontaneously contracting cardiac myocyte-like cells could be generated as well. Multilineage differentiation was confirmed by morphology, protein expression, and upregulation of lineage-specific mRNA. The potential for engineering myocardial tissue was then investigated by transplanting early-passage progenitor cells, organized on a three-dimensional matrix, into the ventricle of an immunocompromised rat utilizing a previously described model of left ventricular tissue engineering. Survival, incorporation into the host myocardium, and cardiomyocytic differentiation of the transplanted cells were confirmed. We have demonstrated that mesenchymal progenitor cells with multilineage potential can be isolated from the fetal liver and have potential utility for autologous tissue engineering.

Mouse vascular endothelium activates CD8+ T lymphocytes in a B7-dependent fashion.

Despite several studies examining the contribution of allorecognition pathways to acute and chronic rejection of vascularized murine allografts, little data describing activation of alloreactive T cells by mouse vascular endothelium exist. We have used primary cultures of resting or IFN-gamma-activated C57BL/6 (H-2(b)) vascular endothelial cells as stimulators and CD8(+) T lymphocytes isolated from CBA/J (H-2(k)) mice as responders. Resting endothelium expressed low levels of MHC class I, which was markedly up-regulated after activation with IFN-gamma. It also expressed moderate levels of CD80 at a resting state and after activation. Both resting and activated endothelium were able to induce proliferation of unprimed CD8(+) T lymphocytes, with proliferation noted at earlier time points after coculture with activated endothelium. Activated endothelium was also able to induce proliferation of CD44(low) naive CD8(+) T lymphocytes. Activated CD8(+) T lymphocytes had the ability to produce IFN-gamma and IL-2, acquired an effector phenotype, and showed up-regulation of the antiapoptotic protein Bcl-x(L). Treatment with CTLA4-Ig led to marked reduction of T cell proliferation and a decrease in expression of Bcl-x(L). Moreover, we demonstrate that nonhemopoietic cells such as vascular endothelium induce proliferation of CD8(+) T lymphocytes in a B7-dependent fashion in vivo. These results suggest that vascular endothelium can act as an APC for CD8(+) direct allorecognition and may, therefore, play an important role in regulating immune processes of allograft rejection.

Mechanism of T cell-mediated endothelial apoptosis.

BACKGROUND: Cytotoxic T lymphocyte (CTL)-mediated destruction of allogeneic vascular endothelium is important in the pathogenesis of both acute and chronic allograft rejection. Despite the importance of this phenomenon, the effector mechanisms responsible for endothelial cell killing are not well defined, and conflicting conclusions have been reached based on variation in experimental methodology. METHODS: We used a recently described method for isolating mouse vascular endothelium to evaluate endothelial cell lysis by CTLs. Endothelial cell destruction was assessed in vitro both by 51Cr release and DNA fragmentation using wild-type and lpr (Fas deficient) endothelium of C3H/HeJ (H2(k)) mice by MHC alloantigen-specific T cells of wild-type, gld (Fas ligand deficient), and perforin-deficient mice on a C57BL/6 (H2(b)) background. RESULTS: Although maximal lysis of 56.6+/-0.8% was seen when using wild-type targets and effectors, only a moderate decrease in apoptosis to 37.6+/-4.0% was detected when the Fas/Fas ligand death receptor pathway was eliminated. This decrease in cytotoxicity occurred despite the preserved functional capacity of this pathway. Alternatively, a significant decrease in cytotoxicity to 17.4+/-4.7% was seen when the perforin/granzyme exocytosis pathway was eliminated. CONCLUSIONS: These data indicate that CTLs destroy vascular endothelium primarily by the perforin/granzyme exocytosis pathway with only a minor contribution to apoptosis by the Fas/Fas ligand death receptor pathway. These data are critical for the proper interpretation of studies evaluating acute and chronic allograft rejection and for the design of rational strategies to ameliorate vascular injury concomitant to the rejection process.

Factors influencing intensive care unit length of stay after surgery for acute aortic dissection type A.

BACKGROUND: Operative mortality after acute aortic dissection type A is still high, and prolonged stay at the intensive care unit is common. Little has been documented about factors influencing the intensive care unit length of stay. The aim of this study was to determine such variables. METHODS: During a 10-year period, 67 patients (47 male, 20 female) were operated on for acute aortic dissection type A. In 42 patients (63%), an ascending aortic replacement was performed, 23 patients (34%) underwent a Bentall procedure, and 2 patients (3%) received a valve-sparing David type of operation. In 14 of these cases (20%), an additional partial or total arch replacement was performed. RESULTS: Hospital mortality was 9 of 67 (14%). Median postoperative intensive care unit length of stay was 5 days (range, 1 to 72 days). Intensive care unit stay was in univariate analysis significantly influenced by the following factors: age (p = 0.008), body mass index (p = 0.039), cardiopulmonary bypass time (p = 0.018), aortic cross-clamp time (p = 0.031), postoperative low cardiac output syndrome (p < 0.001), and postoperative lactate levels (p = 0.01). By multivariate analysis, age (p = 0.012), cardiopulmonary bypass time (p = 0.037), and the presence of a postoperative low cardiac output syndrome (p < 0.001) significantly influenced intensive care unit stay. CONCLUSIONS: Stay in the intensive care unit after operation for acute aortic dissection type A seems to be determined by age, cardiopulmonary bypass time, and the postoperative presence of a low cardiac output syndrome.