Optimizing biogas methanation over nickel supported on ceria-alumina catalyst: Towards CO2-rich biomass utilization for a negative emissions society.

Biogas methanation emerges as a prominent technology for converting biogas into biomethane in a single step. Furthermore, this technology can be implemented at biogas plant locations, supporting local economies and reducing dependence on large energy producers. However, there is a lack of comprehensive studies on biogas methanation, particularly regarding the technical optimization of operational parameters and the profitability analysis of the overall process. To address this gap, our study represents a seminal work on the technical optimization of biogas methanation obtaining an empirical model to predict the performance of biogas methanation. We investigate the influence of operational parameters, such as reaction temperature, H2/CO2 ratio, space velocity, and CO2 share in the biogas stream through an experimental design. Based on previous research we selected a nickel supported on ceria-alumina catalyst; being nickel a benchmark system for methanation process such selection permits a reliable data extrapolation to commercial units. We showcase the remarkable impact of studied key operation parameters, being the temperature, the most critical factor affecting the reaction performance (ca. 2 to 5 times higher than the second most influencing parameter). The impact of the H2/CO2 ratio is also noticeable. The response surfaces and contour maps suggest that a temperature between 350 and 450 °C and an H2/CO2 ratio between 2.5 and 3.2 optimize the reaction performance. Further experimental tests were performed for model validation and optimization leading to a reliable predictive model. Overall, this study provides validated equations for technology scaling-up and techno-economic analysis, thus representing a step ahead towards real-world applications for bio-methane production.

Biochar production from cellulose under reductant atmosphere: influence of the total pyrolysis time.

Today's rising energy costs, coupled with increasing energy demand, make it necessary to search for more efficient energy processes. In recent years, there have been increasing efforts to develop efficient catalysts based on waste-derived char, by a single step where the carbon precursor and the metallic active phase one undergo a single common thermal process under a reductant atmosphere at high temperature. The use of a reductant atmosphere drives the formation of carbonaceous materials with different characteristics than those obtained under the standard nitrogen-inert one. Our work evaluates the influence of the residence time and the heating rate on the physicochemical properties of the biochar obtained. Relatively long residence times and slow heating rates, improve the yield to the resulting biochar, without increasing production cost, making the subsequent char-based metallic catalyst synthesis more efficient. The heating rate was shown to be key in improving the properties of the char in a smoother and more controlled way, unlocking a new working pathway for the efficient design and production of char-based catalysts in a one-pot synthesis.

K-Promoted Ni-Based Catalysts for Gas-Phase CO2 Conversion: Catalysts Design and Process Modelling Validation.

The exponential growth of greenhouse gas emissions and their associated climate change problems have motivated the development of strategies to reduce CO2 levels via CO2 capture and conversion. Reverse water gas shift (RWGS) reaction has been targeted as a promising pathway to convert CO2 into syngas which is the primary reactive in several reactions to obtain high-value chemicals. Among the different catalysts reported for RWGS, the nickel-based catalyst has been proposed as an alternative to the expensive noble metal catalyst. However, Ni-based catalysts tend to be less active in RWGS reaction conditions due to preference to CO2 methanation reaction and to the sintering and coke formation. Due to this, the aim of this work is to study the effect of the potassium (K) in Ni/CeO2 catalyst seeking the optimal catalyst for low-temperature RWGS reaction. We synthesised Ni-based catalyst with different amounts of K:Ni ratio (0.5:10, 1:10, and 2:10) and fully characterised using different physicochemical techniques where was observed the modification on the surface characteristics as a function of the amount of K. Furthermore, it was observed an improvement in the CO selectivity at a lower temperature as a result of the K-Ni-support interactions but also a decrease on the CO2 conversion. The 1K catalyst presented the best compromise between CO2 conversion, suppression of CO2 methanation and enhancing CO selectivity. Finally, the experimental results were contrasted with the trends obtained from the thermodynamics process modelling observing that the result follows in good agreement with the modelling trends giving evidence of the promising behaviour of the designed catalysts in CO2 high-scale units.

Exaggerated placental site/placental site trophoblastic tumor: an underestimated risk factor for emergency peripartum hysterectomy.

OBJECTIVE: To assess the indications and possible underlying causes of emergency peripartum hysterectomy (EPH) at the present hos- pital during the 2001-2011 period. MATERIALS AND METHODS: A revision of the charts and pathology reports corresponding to 42,728 parturients. RESULTS: During the study period, 25 peripartum hysterectomies were performed (0.61/1.000), of which 23 were EPHs (0.54/1.000) and two were planned cesarean hysterectomies. The indication for EPH was acute postpartum hemorrhage in 22 of 23 instances (95.7%). Roughly two-thirds of the operated uteri (16/25, 64%) showed placental site anomalies, half corresponding to different degrees of placental accretism and half to anomalies derived from the implantation site intermediate trophoblast. In five cases (31%), the anomaly was an exaggerated placental site and three cases corresponded to placental site trophoblastic tumors. Of the 16 cases showing placental site anomalies, ten (62.5%) were associated with one or more previous cesarean sections. CONCLUSIONS: Roughly one-third of EPHs performed at the present center during the last ten years were associated with placental site anomalies originating in the implantation site intermediate trophoblast (exaggerated placental site and placental site trophoblastic tumor). This association has not been described before, and should be taken into consideration when facing acute peripartum hemorrhage predisposing to EPH.

[Histopathological findings and biomarker analysis in cutaneous graft-versus-host disease ]. / Histología y biomarcadores en la enfermedad del injerto contra el huésped cutánea.

Graft-versus-host disease (GVHD) remains the greatest source of morbidity-mortality in allogenic transplant patients. Although in most cases the more easily obtainable clinical and laboratory test parameters suffice to confirm the diagnosis and establish the stage of the disease biopsies of the affected organ are sometimes needed. At present there is great Interest in the study of factors allowing a prognosis of the course and type of response to treatment in patients with CVHD. In this sense, It would be necessary to objectively Identify and validate biomarkers capable of predicting biological or pathological processes in patients with cVHD. To this effect we have performed serial analyses of skin tissue using peripheral blood and tissue biomarkers in a prospective observational study conducted in three transplant centers. The still preliminary results Indicate that certain histopathological findings classically attributed to CVHD ore also seen in patients not clinically affected by the disease--this probably being related to other physiopathological phenomena occurring during transplantation. The study of these findings, combined with biomarker analysis, will allow improved understanding of the underlying etiopathogenesis, as well as the definition of new diagnostic, prognostic and response-evaluating criteria.

Fibrous MnO2 nanoparticles with (2 x 2) tunnel structures. Catalytic activity in the total oxidation of volatile organic compounds.

Manganese oxides having 2 x 2 tunnel structures (cryptomelanes) have been synthesized by a milling method in order to test their efficiency as catalysts for the abatement of volatile organic compounds, using toluene as probe molecule. These materials present excellent textural properties, arising from the nanofiber morphology and were active for toluene total oxidation. DRIFTS of the adsorbed phase allow proposing the role of lattice oxygen in the catalytic reaction.

Pt/TiO2 brain biocompatible nanoparticles: GBM treatment using the C6 model in Wistar rats.

In the present work we synthesized inorganic oxide nanoparticle carriers of platinum compounds and tested their therapeutic effect on animal models in which C6 glioma cells have been inoculated. TiO(2)-containing Pt(NH(3))(4)Cl(2) complexes were synthesized using sol-gel methods. The platinum species are chemically bonded to the TiO(2) carrier, as shown by Fourier transform infrared spectroscopy of probe molecules. Treatment with TiO(2)-Pt nanoparticles reduces tumour growth rate by up to 56%, showing that a synergistic effect exists between the TiO(2) carrier and the platinum drug.

Apatite and Portland/apatite composite cements obtained using a hydrothermal method for retaining heavy metals.

Apatite and Portland/apatite composite cements containing steelwork dusts have been prepared using a low temperature hydrothermal method (200 degrees C, 48h). The produced solids were characterized by means of XRD, IR, and SEM-EDX, and the remaining liquid was analyzed by ICP. The results clearly show the capability of these cements to inertise the heavy metals contained in steelwork dusts, that is Fe, Pb, Mo, Cr, Mn, Ni, and Zn. In the case of apatitic cements, Fe, Mg, Cr, Mn, and Pb coming from steel dust replaced Ca in the divalent cation position of the apatite structure, while Si and Mo replaced P in tetrahedral position. The average crystal size of the apatite-containing dust is smaller than in pure apatite synthesized using the same procedure, which is related to the magnesium content of the dust, since magnesium seems to inhibit the crystal growth. XRD diagrams of composite cements show only peaks corresponding to phases observed in the single cements, and in that no new phases are found. However, EDX analysis reveals the introduction of cations coming from Portland cement into the apatite structure. From the results of water analysis it could be concluded that the capability of retention is higher in composite matrices than in the pure apatite one. In conclusion, the obtained data allow stating that the proposed method, the hydrothermal synthesis of steelwork dust containing cement, is a reliable one for immobilization of toxic residues containing heavy leachable cations.

Photocatalytic degradation of 2,4-dichlorophenoxyacetic acid over ZrO2, Cu/ZrO2 and Fe/ZrO2 photocatalysts synthesized by sol gel method.

Photocatalytic oxidation of 2,4-dichlorophenoxyacetic acid was performed over ZrO2, Cu/ZrO2 and Fe/ZrO2 catalysts prepared by the sol-gel method. The samples were annealed at 400 degrees C. Textural and electronic characterization was carried out using BET and UV-Vis in order to establish the relationship between surface, pore volume and E(g) with the photoactivity of the materials. The degradation of the acid was followed by UV-Vis spectroscopy. The disappearance of the herbicide in solution follows approximately pseudo-first order kinetics. The apparent rate constants were calculated for the three catalysts. The results reveal that Fe/ZrO2 exhibits the best photoactivity for the degradation of 2,4-dichlorophenoxyacetic acid.

Growth of hydroxyapatite in a biocompatible mesoporous ordered silica.

A novel biomaterial (HA-SBA-15) has been developed based on the growth of calcium phosphate hydroxyapatite (HA) nanoparticles within an organized silica structure (SBA-15). Characterization of the material was carried out using a combination of X-ray diffraction, X-ray fluorescence, transmission electron microscopy, N2 adsorption-desorption isotherms and nuclear magnetic resonance. Transmission electron microscopy observations and N2 porosimetry revealed the crystallization of hydroxyapatite nanoparticles inside the mesopore cavities of the silica structure. Specific surface areas of 760 m2 g(-1) and 260 m2 g(-1) were measured for the SBA-15 and the HA-SBA-15 material, respectively. The hydroxyl groups present in the silica nanostructure surface have brought about cationic defects in the silicium sites, mainly with those of tetrahedral symmetry, and promoted the formation of siloxanes. 29Si MAS-NMR analysis shows a significant reduction of the silanol groups concentration with HA growing within the base (SBA-15) material. Studies and brain tissue biocompatibility tests were carried out. Histopathological studies on the SBA-15 implant material showed no changes to the tissue nearby. The results confirmed the synthesis of a silica-based composite containing HA nanoparticles with the potential for biomedical applications.

Identification of genes involved in imatinib resistance in CML: a gene-expression profiling approach.

The use of the tyrosine kinase inhibitor imatinib, which blocks the enzymatic action of the BCR-ABL fusion protein, has represented a critical advance in chronic myeloid leukemia (CML) treatment. However, a subset of patients initially fails to respond to this treatment. Use of complementary DNA (cDNA) microarray expression profiling allows the identification of genes whose expression is associated with imatinib resistance. Thirty-two CML bone marrow samples, collected before imatinib treatment, were hybridized to a cDNA microarray containing 6500 cancer genes, and analyzed using bootstrap statistics. Patients refractory to interferon-alpha treatment were evaluated for cytogenetic and molecular responses for a minimum of 12 months. A set of 46 genes was differentially expressed in imatinib responders and non-responders. This set includes genes involved in cell adhesion (TNC and SCAM-1), drug metabolism (cyclooxygenase 1), protein tyrosine kinases and phosphatases (BTK and PTPN22). A six-gene prediction model was constructed, which was capable of distinguishing cytogenetic response with an accuracy of 80%. This study identifies a set of genes that may be involved in primary resistance to imatinib, suggesting BCR-ABL-independent mechanisms.

A randomized study of intermediate as compared with high doses of interferon-alpha for chronic myeloid leukemia: no differences in cytogenetic responses.

Interferon-alpha (IFN-alpha) is a therapy of unquestionable efficacy in chronic myeloid leukemia (CML) patients. The best dose of IFN-alpha in the treatment of CML still remains controversial. Our primary objective was to compare cytogenetic responses in patients treated with intermediate versus high doses of IFN-alpha. A multicenter randomized controlled trial was conducted involving 109 patients with untreated CML in chronic phase from 26 Spanish hospitals. Patients were assigned to receive either an intermediate (2.5 MU/m(2) per day) or high (5 MU/m(2) per day) target dose of IFN-alpha. Hydroxyurea was allowed in both groups. In total, 108 patients were analyzed, 53 in the intermediate- and 55 in the high-dose group. Median follow-up was 47.5 months. The dose of IFN-alpha actually given was lower in the intermediate-dose group (3.83 MU/day) than in the high-dose group (6.6 MU/day) ( p<0.001). The rate of complete cytogenetic response was 24.5% in the intermediate- and 12.7% in the high-dose group (NS). A partial cytogenetic response was obtained in 7.5% and 10.9%, respectively. Cox analysis did not reveal any influence of the randomization arm on cytogenetic response rate. Ten patients in each group discontinued IFN-alpha because of toxicity. Albeit not our primary objective, no differences were found in terms of survival or transformation rate between both groups. Median survival was 73 months; 64% of patients remained free of transformation at 5 years. In terms of cytogenetic response, intermediate doses of IFN-alpha are as effective as high doses in the treatment of CML.

Therapy-related acute promyelocytic leukemia.

PURPOSE: To analyze patient cases of therapy-related acute promyelocytic leukemia (tAPL), occurring after chemotherapy (CT), radiotherapy (RT) or both for a prior disorder, diagnosed during the last 20 years in three European countries. PATIENTS AND METHODS: The primary disorder and its treatment, interval from primary disorder to tAPL, characteristics of tAPL, and its outcome were analyzed in 106 patients. RESULTS: Eighty of the 106 cases of tAPL were diagnosed during the last 10 years, indicating an increasing incidence of tAPL. Primary disorders were predominantly breast carcinoma (60 patients), non-Hodgkin's lymphoma (15 patients), and other solid tumors (25 patients). Thirty patients had received CT alone, 27 patients had received RT alone, and 49 patients had received both. CT included at least one alkylating agent in 68 patients and at least one topoisomerase II inhibitor in 61 patients, including anthracyclines (30 patients), mitoxantrone (28 patients), and epipodophyllotoxins (19 patients). Median interval from primary disorder to tAPL diagnosis was 25 months (range, 4 to 276 months). Characteristics of tAPL were generally similar to those of de novo APL. With treatment using anthracycline-cytarabine-based CT or all-trans-retinoic acid combined with CT, actuarial survival was 59% at 8 years. CONCLUSION: tAPL is not exceptional, and develops usually less than 3 years after a primary neoplasm (especially breast carcinoma) treated in particular with topoisomerase II-targeted drugs (anthracyclines or mitoxantrone and less often etoposide). Characteristics and outcome of tAPL seem similar to those of de novo APL.

Low transplant-related mortality after second allogeneic peripheral blood stem cell transplant with reduced-intensity conditioning in adult patients who have failed a prior autologous transplant.

Standard allogeneic stem cell transplantation (SCT) has been associated with a high transplant-related mortality (TRM) in patients who have failed a prior autologous SCT (ASCT). Reduced-intensity conditioning (RIC) regimens may reduce the toxicities and TRM of traditional myeloablative transplants. We report 46 adults who received a RIC peripheral blood SCT from an HLA-identical sibling in two multicenter prospective studies. The median interval between ASCT and allograft was 16 months, and the patients were allografted due to disease progression (n = 43) and/or secondary myelodysplasia (n = 4). Conditioning regimens consisted of fludarabine plus melphalan (n = 41) or busulphan (n = 5). The 100-day incidence of grade II-IV acute graft-versus-host disease (GVHD) was 42% (24% grade III-IV), and 10/30 evaluable patients developed chronic extensive GVHD. Early complete donor chimerism in bone marrow and peripheral blood was observed in 35/42 (83%) patients, and 16 evaluable patients had complete chimerism 1 year post transplant. With a median follow-up of 358 days (450 in 29 survivors), the 1-year incidence of TRM was 24%, and the 1-year overall (OS) and progression-free survival were 63% and 57%, respectively. Patients who had chemorefractory/ progressive disease, a low performance status or received GVHD prophylaxis with cyclosporine A alone (n = 32) had a 1-year TRM of 35% and an OS of 46%, while patients who had none of these characteristics (n = 32) had a 1-year TRM of 35% and an OS of 46% while patients who had none of these characteristics (n = 14) had a TRM of 0% and an OS of 100%. Our results suggest that adult patients who fail a prior ASCT can be salvaged with a RIC allogeneic PBSCT with a low risk of TRM, although patient selection has a profound influence on early outcome.

CsA-based post-graft immunosuppression: the main factor for improving outcome of allografted patients with acquired aplastic anemia. A retrospective survey by the Spanish Group of Hematopoietic Transplantation.

A retrospective multicenter study was performed to assess the clinical results in patients with acquired aplastic anemia (AA) allografted over a 19 year period and to identify prognostic factors influencing survival. From April 1978 to December 1997, 176 patients were transplanted. Records from 160 receiving related matched bone marrow transplantation (BMT) were reviewed. Fifty-two percent of the patients were older than 20 years, 5% older than 40; 6.3% were untransfused at BMT and 56.2% had received prior treatments. Conditioning regimens were with chemotherapy in 43.7% of the procedures and with additional irradiation in 56.3%. Graft-versus-host disease (GVHD) prophylaxis was based on cyclosporin A (CsA) in 58.1% of the patients while methotrexate (MTX) was administered to 41.9%. Transplantation earlier on, a longer interval from diagnosis to BMT, GVHD prophylaxis with MTX, graft failure/rejection and acute severe GVHD were adverse factors for survival. The use of CsA emerged as the main factor for the improvement, inducing a significant decrease in graft failure/rejection rate and severe acute GVHD when compared with MTX alone. Radiation-containing regimens decreased the graft failure/rejection rate without improving survival due to the increased risk of acute GVHD. Age and number of transfusions pretransplant did not influence outcome. Survival achieved since 1991 is 79.79%, and graft failure and acute severe GVHD rates are 6.0% and 11.8%, respectively. In conclusion, CsA-based post-graft immunosuppression has been crucial in achieving improved survival in patients with acquired AA up to 40 years of age. Regardless of CsA use, further improvement in survival was apparent with time, probably due to better skills in patient care.

Allogeneic peripheral blood stem cell transplantation with reduced-intensity conditioning: results of a prospective multicentre study.

Reduced-intensity conditioning (RIC) regimens for allogeneic haematopoietic stem cell transplantation (SCT) have been shown to lead to engraftment of donor stem cells without the severe extra-haematological toxicities of traditional myeloablative transplants. Between December 1998 and December 2000, 76 patients underwent a RIC peripheral blood SCT in a prospective multicentre study. The median age was 53 years, and 57 patients were beyond the early phase of their disease. The conditioning regimens consisted of fludarabine (150 mg/m2) plus melphalan (140 mg/m2) or busulphan (10 mg/kg). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporin A plus short-course methotrexate. The preparative regimens were well tolerated. All patients experienced severe pancytopenia, but haematological recovery was prompt in all but two cases (early deaths). The 100-d probability of developing grade II-IV acute GVHD was 32% (10% grade III-IV), and the 1-year probability of developing chronic extensive GVHD was 43%. Early complete donor chimaerism was observed in 52/68 patients, and 16 evaluable patients were in complete chimaerism 1 year post transplant. With a median follow-up of 283 d (355 in 48 survivors), the 1-year probability of transplant-related mortality was 20%, and the 1-year overall and progression-free survivals were 60% and 55% respectively. In conclusion, RIC regimens lead to low early toxicity after allografting, with stable donor haematopoietic engraftment, with an apparent low risk of acute GVHD. Chronic GVHD, however, develops in a significant proportion of patients.

Allogeneic transplantation of CD34+-selected cells from peripheral blood in patients with myeloid malignancies in early phase: a case control comparison with unmodified peripheral blood transplantation.

An allogeneic transplantation of CD34(+)-selected cells from peripheral blood (allo-PBT/CD34(+)) from HLA-identical sibling donors was performed in 50 adult patients with acute myeloid leukemia in first complete remission (AML CR1) (n = 29), myelodysplastic syndrome (MDS) (n = 4), or chronic myeloid leukemia in first chronic phase (CML CP1) (n = 17). Clinical results were compared to a concurrent group of 50 patients transplanted with unmodified peripheral blood progenitor cells (allo-PBT), matched for age, diagnosis, and disease stage. The median follow-up period was 29 months (range 1-69). The actuarial probability of developing acute GVHD clinical grade II to IV was 16% (95%CI: 6-26) for the allo-PBT/CD34(+) group and 41% (95%CI: 29-57) for the allo-PBT group (P = 0.002). The actuarial probability of developing extensive chronic GVHD was 22% (95%CI: 8-36) for the allo-PBT/CD34(+) group and 47% (95%CI: 31-63) for the allo-PBT group (P = 0.02). Recipients of allo-PBT/CD34(+) had less toxicity associated with the transplant and better Karnofsky index at the last follow-up. For AML/MDS patients, the actuarial probability of disease-free survival (DFS) for recipients of allo-PBT/CD34(+) and allo-PBT was 65% (95%CI: 45-85) vs43% (95%CI: 28-58) (P = 0.05), respectively. These data provide a rationale for a randomised trial of allo-PBT/CD34(+) vs allo-PBT in AML/MDS patients in early stage of the disease.

Additional cytogenetic changes do not influence the outcome of patients with newly diagnosed acute promyelocytic leukemia treated with an ATRA plus anthracyclin based protocol. A report of the Spanish group PETHEMA.

BACKGROUND AND OBJECTIVES: To analyze in patients with de novo acute promyelocytic leukemia (APL) treated with an ATRA plus anthracyclin-based protocol if the presence of additional cytogenetic aberrations to the t(15;17) influences: 1. clinical and biological presenting features; 2. disease outcome. DESIGN AND METHODS: One hundred and thirteen patients with newly diagnosed APL enrolled in the APL-96 protocol of the Spanish PETHEMA group were studied by conventional karyotyping, FISH and RT-PCR for the PML-RARa fusion. Treatment was homogeneous in all cases and consisted of anthracyclines and ATRA. RESULTS: Additional chromosome aberrations were observed in 30% of cases. The most frequent secondary changes were +8 (14 cases), and abnormalities of chromosomes 9 or 3 (4 patients each), and of chromosomes 1 and 8 (3 cases each). No clinical, biological, morphological, immunophenotypic or molecular differences were observed between the group of APLs with t(15;17) alone and the group of patients with additional changes. Patients with additional changes had a higher rates of complete remission (CR) and 4-year disease-free survival (DFS) (97%, and 97%, respectively) than patients with t(15;17) alone (CR, 70% and DFS, 84%) but these differences were not statistically significant. INTERPRETATION AND CONCLUSIONS: Patients with APL and additional cytogenetic abnormalities do not show different clinical, biological, morphological or molecular features as compared to patients with t(15;17) alone. The prognosis of patients with APL and t(15;17) alone and those with additional changes is similar in both groups. This study indicates that there is no rationale for administering more intensive treatment in APL patients with additional cytogenetic abnormalities receiving ATRA plus anthracycline-based chemotherapy.

Is veno-occlusive disease a specific syndrome or the exacerbation of physiopathologic hemostatic changes in hematopoietic stem cell transplantation (HSCT)?

The objective of the present study was to analyze whether veno-occlusive disease (VOD) is based on specific findings or whether this syndrome is the exacerbation of changes in hemostatic parameters that develop following hematopoietic stem cell transplantation (HSCT). 40 patients undergoing HSCT were enrolled (6 allogeneic bone marrow transplantation and 34 peripheral stem cell rescue-2 allogeneic, 32 autologous). Measurements of hemostatic parameters (endothelial, hypercoagulability and fibrinolytic markers) were obtained prior to chemotherapy and weekly thereafter for 3 weeks. The incidence of VOD was 15%. HSCT showed a state of moderate hypercoagulability (increase of thrombin-antithrombin complex and fibrinogen, and decrease of Factor VII, Protein C, and antithrombin-III), probably as a consequence of marked endothelial damage (increase of von Willebrand Factor and tissue plasminogen activator). All these alterations create a potentially prothrombotic state, more pronounced in VOD. The decreasing incidence of VOD and the moderate disease in all patients suggest that increasing improvements in transplant strategies have reduced the risk and severity of a syndrome that at the beginning of the transplantation era was a leading cause of morbidity/mortality.