One of the greatest advances in medicine during the past century is the introduction of organ transplantation. This therapeutic strategy designed to treat organ failure and organ dysfunction allows to prolong the survival of many patients that are faced with no other treatment option. Today, organ transplantation between genetically dissimilar individuals (allogeneic grafting) is a procedure widely used as a therapeutic alternative in cases of organ failure, hematological disease treatment, and some malignancies. Despite the potential of organ transplantation, the administration of immunosuppressive drugs required for allograft acceptance induces severe immunosuppression in transplanted patients, which leads to serious side effects such as infection with opportunistic pathogens and the occurrence of neoplasias, in addition to the known intrinsic toxicity of these drugs. To solve this setback in allotransplantation, researchers have focused on manipulating the immune response in order to create a state of tolerance rather than unspecific immunosuppression. Here, we describe the different treatments and some of the novel immunotherapeutic strategies undertaken to induce transplantation tolerance.

cells do not affect the recruitment of immunosuppressive populations but favour the recruitment of effector Th1 cells to the tumour, thereby promoting anti-tumour responses.

Growth kinetics of Desulfovibrio desulfuricans, strain NCIMB 9467, was studied in laboratory scale, under well-controlled batch conditions. This research is oriented toward the practical, industrial removal of sulfate and metal ions from mine water. Growth of the microorganism in such waters was verified.From 290 experimental observations ofsulfate and lactate (obtained from 145 culture tubes of 20 mL) the parameters of a Monod model were estimated. Inoculum mass was not measured but it was incorporated as another model parameter. Hydrogen sulfide was removed by addition of ferrous iron, which rapidly formed iron sulfide and precipitated toward the bottom of the culture tube. Parameters were estimated by a nonlinear least squares parameter minimizer. The growth-limiting substrate was the sulfate concentration. Under these conditions the growth of Desulfovibrio desulfuricans was characterized by a maximum growth rate of 25 .h-*, a sulfate affinity constant of 850 mg/L, and a reduced sulfate yield of 6.2 .(biomass per sulfate mass). Inoculum was 1.97 mg of bacteria& and the consumption of lactate was characterized by a yield of 2.5 . lo-' (biomass per lactate mass). Sulfate was reduced at a rate of 400 mg/L/day while lactate was oxidized at a rate of 1100 mglliday.Mine wastewater was used as sulfate source and complemented with lactate as the carbon source. Under these conditions the strain growth was similar to that obtained with the controlled media. It was concluded that no inhibitory effects exist. The reduction velocity obtained, 200 mg/L/day, was lower than before, probably due to inoculum size or strain adaptation.A novel process is proposed to produce solid sulfur from sulfate and sulfur oxides.

The induction of donor-specific transplant tolerance is one of the main goals of modern immunology. Establishment of a mixed chimerism state in the transplant recipient has proven to be a suitable strategy for the induction of long-term allograft tolerance; however, current experimental recipient preconditioning protocols have many side effects, and are not feasible for use in future therapies. In order to improve the current mixed chimerism induction protocols, we developed a non-myeloablative bone-marrow transplant (NM-BMT) protocol using retinoic acid (RA)-induced alloantigen-specific Tregs, clinically available immunosuppressive drugs, and lower doses of irradiation. We demonstrate that RA-induced alloantigen-specific Tregs in addition to a NM-BMT protocol generates stable mixed chimerism and induces tolerance to allogeneic secondary skin allografts in mice. Therefore, the establishment of mixed chimerism through the use of donor-specific Tregs rather than non-specific immunosuppression could have a potential use in organ transplantation.

The growth of Thiobacillus ferrooxidans in a copper-containing ore suspension incubated in shake flasks was studied by determining the number of colony-forming units both in solution and attached to ore particles. The amounts of iron and copper released from the ore under experimental conditions were also determined. The total ferrous iron either released from the minerals or generated by reduction of the ferric iron in the minerals could account for the observed growth of bacteria in solution. Only a small fraction of the total colony-forming units-about 500 per mg ore-was found to be associated with the ore particles throughout the experiments. However, the rapid development of these colonies when ore particles were plated suggested that they were produced by a number of bacteria associated with each ore particle. Accordingly, when the amount of bacteria attached to ore particles was determined by monitoring the formation of ferric iron in the plates, the percentage of the total activity associated with attached bacteria was found to be between 1 and 10%.