Evaluation of microaeration strategies in the digestion zone of UASB reactors as an alternative for biogas desulfurization

This study aimed at evaluating the microaeration as an alternative for hydrogen sulfide removal from biogas of UASB reactors treating sewage. The set-up consisted of two pilot-scale UASB reactors, including a conventional anaerobic and a modified UASB reactor, operated under microaerated conditions. Air was supplied in the digestion zone, at 1 and 3 m from the bottom of the reactor, and three different air flows were investigated: 10, 20, and 30 mL.min^-1, corresponding to 0.003, 0.005 and 0.005 LO₂/L_influent, respectively. The main results showed that the microaeration provided a substantial decrease in hydrogen sulfide concentrations when compared to the concentrations observed in the biogas of the anaerobic UASB reactor. Hydrogen sulfide concentrations remained below 70 ppm_v throughout the experimental period, corresponding to an average removal efficiency of 98%. Although a decrease in methane concentrations in biogas was observed, the feasibility of energy use would not be affected. The effect of microaeration on the overall performance of the reactor was evaluated, however, no significant differences were observed. The feasibility of limiting aeration conditions in the reactor digestion zone as an efficient alternative for hydrogen sulfide removal from biogas was demonstrated.

Performance and bacterial diversity of bioreactors used for simultaneous removal of sulfide, solids and organic matter from UASB reactor effluents

Two bioreactors were investigated as an alternative to post-treatment of effluent from an upflow anaerobic sludge blanket (UASB) reactor treating domestic sewage, with an aim of oxidizing sulfide into elemental sulfur, and removal of solid and organic material. The bioreactors were operated at different hydraulic retention times (HRTs) (6, 4, and 2 h) and in the presence or absence (control) of packing material (polypropylene rings). Greater sulfide removal efficiencies - 75% (control reactor) and 92% (packed reactor) - were achieved in both reactors for an HRT of 6 h. Higher organic matter (COD) and solid (TSS) removal levels were observed in the packed reactor, which produced effluent with low COD (100 mg CODL^-1) and TSS concentrations (30 mg TSSL^-1). Denaturing gradient gel electrophoresis results revealed that a metabolically diverse bacterial community was present in both bioreactors, with sequences related to heterotrophic bacteria, sulfur bacteria (Thiocapsa, Sulfurimonas sp., Chlorobaculum sp., Chromatiales and Sulfuricellales), phototrophic purple non-sulfur bacteria (Rhodopseudomonas, Rhodocyclus sp.) and cyanobacteria. The packed reactor presented higher extracellular sulfur formation and potential for elemental sulfur recovery was seen. Higher efficiencies related to the packed reactor were attributed to the presence of packing material and higher cell retention time. The studied bioreactors seemed to be a simple and low-cost alternative for the post-treatment of anaerobic effluent.

Drought promotes increases in total mercury and methylmercury concentrations in fish from the lower Paraíba do Sul river, southeastern Brazil

Bioaccumulation of mercury and methylmercury in fish represents a serious risk to human beings. Extreme climate events like droughts may increase the trophic transfer of contaminants and net methylation of mercury. The present study assessed the influence of the 2014 drought on total mercury and methylmercury levels in fish from the lower Paraiba do Sul river basin. Contaminant levels were compared for Pimelodus fur, Pachyurus adspersus, Pimelodella lateristriga, Oligosarcus hepsetus, and Crenicichla lacustris captured in five sites in 2013 (N = 212) and 2014 (N = 231). The results indicate that levels of contaminants were higher during the drought in most species. Rainfall was weakly and negatively correlated with total mercury levels in most of the species. The weak relationship between these two variables was due to the indirect influence of rainfall on mercury bioaccumulation. In summary, drought increased the levels of two contaminants in fish.

Organotropism of methylmercury in fish of the southeastern of Brazil

This is one of the first studies to evaluate the effect of biometric variables (total length and weight), diet, and abiotic matrices (sediment and water column) on the bioaccumulation of methylmercury in tissues (muscle, liver, and gills) of four fish (two carnivore-invertivores, Pimelodus fur and Pachyurus adspersus; one carnivore-piscivore, Oligosarcus hepsetus; and one omnivore, Pimelodella lateristriga) in the lower section of a river in southeastern Brazil. Samples of fish (n = 120), water (n = 5) and sediment (n = 5) were collected at five sites characterized by pollution with mercury due to the use of organomercury fungicides and stream bed gold mining, commonly carried out in that section of the river in the 1980s. The results show that biometric variables are strongly correlated with methylmercury levels in muscle (r = 0.61, p < 0.0005) of P. fur. As a rule, concentrations of total mercury and methylmercury did not vary considerably between the organs of the species of different food habits, because of the environmental conditions in the study area. Despite the low concentrations of mercury in sediments (<0.05 mg kg^-1 wet. wt), this compartment is a representative source of this pollutant for the organisms investigated, due to the close contact these animals keep with it in view of the low water columns in that section of the river.

Yellow fever vaccination in organ transplanted patients: is it safe? A multicenter study

BACKGROUND

Yellow fever (YF) may be very serious, with mortality reaching 50%. Live attenuated virus YF vaccine (YFV) is effective, but may present, although rare, life-threatening side effects and is contraindicated in immunocompromised patients. However, some transplant patients may inadvertently receive the vaccine.

METHODS

A questionnaire was sent to all associated doctors to the Brazilian Organ Transplantation Association through its website, calling for reports of organ transplanted patients who have been vaccinated against YF.

RESULTS

Twelve doctors reported 19 cases. None had important side effects. Only one had slight reaction at the site of YFV injection. Eleven patients were male. Organs received were 14 kidneys, 3 hearts, and 2 livers. Twelve patients received organs from deceased donors. Mean age at YFV was 45.6 ± 13.6 years old (range 11-69); creatinine: 1.46 ± 0.62 mg/dL (range 0.8-3.4); post-transplant time: 65 ± 83.9 months (range 3-340); and time from YFV at the time of survey: 45 ± 51 months (range 3-241). Immunosuppression varied widely with different drug combinations: azathioprine (7 patients), cyclosporine (8), deflazacort (1), mycophenolate (10), prednisone (11), sirolimus (3), and tacrolimus (4).

CONCLUSIONS

YFV showed no important side effects in this cohort of solid organ transplanted patients. However, owing to the small number of studied patients, it is not possible to extend these findings to the rest of the transplanted population, assuring safety. Therefore, these data are not strong enough to safely recommend YFV in organ transplanted recipients, as severe, even life-threatening side effects may occur.

Incidence of delayed graft function in cadaveric kidney transplants in Brazil: a multicenter analysis

To evaluate the frequency of delayed graft function (DGF) in kidney transplant centers in Brazil, we sent a questionnaire requesting information on the number of cadaveric donor kidney transplants performed during the years 2000, 2001, and 2002, the number of early nonfunctioning grafts, and the number of patients on dialysis during the first posttransplant week with subsequent recovery. Among all centers performing more than 50 kidney transplants during the last year of evaluation, 6, performing 612 cadaveric kidney transplants during the study period, replied to the questionnaire. Sixty procedures (9.7%) resulted in nonfunctioning grafts, while 312 (55.6%) patients required dialysis during the first Ptx week: 216 (53.9%) in 2000, 189 (62.3%) in 2001, and 216 (51.6%) in 2002. The frequency of DGF during the study period was higher than that noted by several previous foreign studies. To better evaluate the possible causes of this finding, a more extensive and focused study is warranted.

Renal transplantation in systemic lupus erythematosus. A case control study of 45 patients

BACKGROUND

Outcome and the issue of recurrence of disease in systemic lupus erythematosus (SLE) renal transplant recipients is still a matter of controversy. There is a lack of comparative studies with non-SLE patients. The aim of this paper is to compare renal transplantation in lupus patients with a similar matched non-SLE group.

METHODS

Forty-five patients with systemic lupus erythematosus subjected to 48 kidney transplants were studied. For comparative purposes, a case-control population was selected, matched for gender, race, type of donor, age, and time of transplantation. Patients with non-glomerulonephritis diseases were excluded.

RESULTS

No differences in acute episodes of rejection, causes of kidney loss or patient death were observed. General as well as infectious complications were similar. Pregnancy rates and outcomes were similar with no deleterious effect on patients or grafts. Actuarial 1- and 5-year patient survivals (97.7 and 91.1% for SLE and 95.4 and 87% for controls, respectively) and graft survivals (93.1 and 80.7% for SLE and 88.8 and 70.2% for controls, respectively) were similar. Long-term renal function expressed by serum creatinine was the same. No differences in immunosuppressive drug (azathioprine, prednisone, and cyclosporin) requirements were found. Clinical SLE recurrence was suspected only once (a patient with thrombocytopenia, hypocomplementaemia with low complement levels and positive antiplatelet antibodies). Two SLE patients showed mesangial proliferative glomerulonephritis compatible with recurrence. Both grafts were lost. Two further patients showed membranous glomerulonephritis with an immunofluorescence pattern compatible with recurrence. A fifth patient had necrotizing arteritis which recovered after treatment with cyclophosphamide and another patient showed focal and segmental glomerulosclerosis. Histology of biopsies from five patients in the control group showed signs compatible with recurrence of focal and segmental glomerulosclerosis and membranous glomerulonephritis. There was a wide variation in serum levels of antinuclear antibodies. A wide variation in complement levels was also observed, but with a tendency towards low C4 levels.

CONCLUSIONS

The safety of renal transplantation in SLE patients is equivalent to a matched case-control group with a similar rate of recurrence of disease.

The role of experimental chronic renal failure and aluminium intoxication in cellular immune response

BACKGROUND

A positive correlation between successful kidney transplantation, few rejection episodes, greater susceptibility to infection and morbidity in patients with high tissue levels of aluminium (Al) indicate that the metal may play a role in the immune response. The aim of this study was to determine if experimental aluminium intoxication could result in significant changes in lymphocyte activity in uraemic and nonuraemic rats.

METHODS

Lewis rats were divided into four groups: normals (N), nephrectomized control (U), and Al-treated (N + Al) and nephrectomized Al-treated (U + Al), which received a cumulative dose of 30 mg Al over a 4-week period. Al quantification, histology, histochemical analysis and immunological assays were performed after Al intoxication.

RESULTS

High tissue levels of Al and positive histochemical staining in bones were seen in Al-treated rats. Bone histology revealed osteomalacia in U + Al rats. No statistical differences were observed in mixed lymphocyte cultures from controls and Al-treated rats, whereas U and Al-treated rats showed a decrease in lymphoproliferative response to mitogen and natural killer cell cytotoxic activity. A decreased helper T lymphocyte: cytotoxic T lymphocyte cell ratio and a reduction in interleukin-2 production were observed only in the U + Al group. A reduced number of total T lymphocytes was detected in the spleens of all Al-treated rats.

CONCLUSIONS

These findings suggest that aluminium toxicity may contribute to immunological impairment in chronic renal failure.

The role of experimental aluminum intoxication in allogeneic immunoresponse

To evaluate the immunological properties of aluminum (Al) in experimental Al intoxication in rats, we performed heart transplantation and in vitro experiments. Lewis (Lew) rats were intoxicated with intraperitoneal injections of AlCl3. heart transplants were performed using Brown-Norway (BN) rats as donors. Isotransplants and normal Lew were used as controls. No differences in survival were observed. Unidirectional mixed lymphocyte cultures (MLC) and Concanavalin A (Con A)-stimulated cultures were prepared using spleen cells from normal and Al-intoxicated Lew rats. No differences were found in unidirectional MLC. Intoxicated cells showed a less intense response to con A than did normal cells. In conclusion, we could not detect an immunosuppressive role of Al intoxication in experimental cardiac transplantation or in MLC. However, the depressed Con A blastogenic response of Al-intoxicated cells may reflect an immunological role yet to be defined.

[Comparison of the determination of cyclosporin-A in blood samples collected on filter paper and by the ordinary technique]

Monitoring cyclosporin-A (CsA) blood levels is of utmost importance for the rational use of this drug. Although many centers perform transplants, in Brazil there are few laboratories able to measure CsA blood levels. Therefore making blood samples reach the laboratory emerged as a problem. Collection of blood on filter paper has been a technique used for a long time in special cases. PURPOSE--To confirm the usefulness of measuring CsA blood levels in blood samples collected on filter paper and in the usual way. METHOD--We studied twenty renal cadaver kidney recipients who were receiving CsA, azathioprine and prednisone. Ninety five blood samples were collected and divided into two aliquots. One of them was sent routinely to one laboratory to perform whole blood CsA measurements. From the other aliquot, 20 microliters were pipetted on filter paper. When dried they were mailed to the other laboratory, where, after elution, CsA was measured. In both cases radioimmunoassay with polyclonal antibody was used. RESULTS--Linear correlation between both measurements revealed r = 0.81 with no statistical difference. CONCLUSION--The technique showed to be useful in clinical practice. In countries with continental size, as Brazil, it may be very helpful.

[Cyclosporin A: experience of the Renal Transplant Unit of the Clinical Hospital of the Medical College of the University of Sao Paulo]

The authors report their experience using cyclosporine-A (CsA) in renal transplant patients. When compared with azathioprine/prednisone, CsA contributed significantly to a better graft and patient survival, either if used associated with prednisone of with azathioprine plus prednisone. CsA was also used in substitution to azathioprine in patients with hepatopathy attributed to azathioprine toxicity. The initial results are promising. The association of CsA and azathioprine with corticosteroids withdrawal was used as an attempt to allow normal growth in children. This seems to be the best choice of treatment for children. Careful monitoring of CsA blood levels avoids, or at least, minimizes nephrotoxicity. To achieve therapeutic CsA levels, patients with liver damage need lower, while children need higher oral CsA doses. To summarise: when CsA in carefully used, it is an excellent immunosuppressive drug.

Renal transplantation and schistosomiasis mansoni

Eleven patients with schistosomiasis mansoni received a renal transplant. In 5 patients, the schistosomiasis was asymptomatic and had been diagnosed by routine examinations and had no relationship to nephropathy. In 4 patients, the nephropathy was suggestive of being of schistosomal origin. Three of them had symptomatic hepatosplenic schistosomiasis, and histologic studies of original kidneys disclosed chronic glomerulonephritis in 2 and membranous glomerulonephritis in 1 patient. These histologic pictures do not establish definitively the schistosomal origin of nephropathy. The other patient had membranoproliferative glomerulonephritis that recurred in the allograft, but he had intestinal schistosomiasis. This form of the disease is not considered by all as capable of inducing nephropathy. Two patients had the hallmarks of schistosomal nephropathy: hepatosplenic form and membranoproliferative glomerulonephritis. The 1st patient developed nephrotic syndrome 3 years after the transplantation, and an allograft biopsy disclosed membranoproliferative glomerulonephritis. The other patient had an uneventful outcome with good renal function and no proteinuria. An allograft biopsy performed 14 months after the transplant disclosed slight mesangial proliferation with IgM++ and C3++ in the mesangium.

Tuberculosis in renal transplant patients

Tuberculosis (TB) was diagnosed in 25 of 466 patients who underwent renal transplant over a period of 15 years. TB developed from 1 month to 9 years post-transplant. In 56% of the cases the onset was within the first post-transplant year. TB affected several isolated or combined organs. Pulmonary involvement was present in 76% of cases, either as isolated pleuro-pulmonary (56%) or associated with other sites (20%). The non-pulmonary sites were: skin, joints, tests, urinary tract, central nervous system and lymphonodules. The diagnosis was confirmed by biopsy in 64% of the cases, by identification of tubercle bacilli in 24% and only at necropsy in 12% Biopsy specimens could be classified in three histological forms: exudative, that occurred in early onset and more severe cases granulomatous in late onset and benign cases; and mixed in intermediate cases. Azathioprine dosages were similar along post-transplant time periods in TB patients and in the control groups; and in TB patients who were cured and who died. The number of steroid treated rejection crises was greater in TB than in the control group. Prednisone doses were higher and the number of rejection crises was greater in TB patients who died than in those who were cured. Fifteen patients were cured and ten died, two of them of causes unrelated to TB. Six of the eight TB-related deaths occurred in the first 6 post-transplant months. The outcome was poor in patients in whom TB arose early in post-transplant period and where the exudative or mixed forms were present; whereas the prognosis was good in patients with late onset and granulomatous form of TB. In one patient TB was transmitted by the allograft.