Toxicity of graphene oxide on growth and metabolism of Pseudomonas putida

The increasing consumption of graphene derivatives leads to greater presence of these materials in wastewater treatment plants and ecological systems. The toxicity effect of graphene oxide (GO) on the microbial functions involved in the biological wastewater treatment process is studied, using Pseudomonas putida and salicylic acid (SA) as bacterial and pollutant models. A multiparametric flow cytometry (FC) method has been developed to measure the metabolic activity and viability of P. putida in contact with GO. A continuous reduction in the percentages of viable cells and a slight increase, lower than 5%, in the percentages of damaged and dead cells, suggest that P. putida in contact with GO loses the membrane integrity but preserves metabolic activity. The growth of P. putida was strongly inhibited by GO, since 0.05mgmL(-1) of GO reduced the maximum growth by a third, and the inhibition was considerably greater for GO concentrations higher than 0.1mgmL(-1). The specific SA removal rate decreased with GO concentration up to 0.1mgmL(-1) indicating that while GO always reduces the growth of P. putida, for concentrations higher than 0.1mgmL(-1), it also reduces its activity. Similar behaviour is observed using simulated urban and industrial wastewaters, the observed effects being more acute in the industrial wastewaters.

Toxicity of titanium dioxide nanoparticles on Pseudomonas putida

The increasing use of engineered nanoparticles (NPs) in industrial and household applications will very likely lead to the release of such materials into the environment. As wastewater treatment plants (WWTPs) are usually the last barrier before the water is discharged into the environment, it is important to understand the effects of these materials in the biotreatment processes, since the results in the literature are usually contradictory. We proposed the use of flow cytometry (FC) technology to obtain conclusive results. Aqueous solutions of TiO2 nanoparticles (0-2 mg mL(-1)) were used to check its toxicity effect using Pseudomonas putida as simplified model of real sludge over room light. Physiological changes in P. putida from viable to viable but non-culturable cells were observed by flow cytometry in presence of TiO2. The damaged and dead cell concentrations were below 5% in all cases under study. Both FSC and SSC parameter increased with TiO2 dose dependent manner, indicating nanoparticles uptake by the bacteria. The biological removal of salicylic acid (SA) was also significantly impacted by the presence of TiO2 in the medium reducing the efficiency. The use of FC allows also to develop and fit segregated kinetic models, giving the impact of TiO2 nanoparticles in the physiological subpopulations growth and implications for SA removal.

Age may explain the association of an early dialysis initiation with poor survival

BACKGROUND

Some studies postulate that early dialysis initiation may increase mortality.

AIM

The aim of the present study was to assess to what extent this was due to confounding by age.

DESIGN

Observational retrospective cohort study.

METHODS

We studied all patients starting dialysis therapy between 1 January 1995 and 31 December 2009 in our center. The following variables at dialysis initiation in end-stage renal disease (ESRD) patients were analysed: estimated glomerular filtration rate (eGFR), age, gender, diabetes mellitus, serum albumin, hemoglobin, period of dialysis initiation, history of ischemic heart disease and stroke. Multivariate Cox model was used to calculate adjusted patient survival.

RESULTS

Over the last 15 years, 428 patients initiated dialysis therapy in our reference area. Median eGFR at dialysis initiation was 8.16 ml/min. In the univariate analysis, increased eGFR, age, dialysis initiation 1995-1999/2000-2004, diabetes and history of ischemic heart disease were associated (P < 0.05) with increased mortality in ESRD. Patients that started dialysis program with eGFR > 8.16 were older than those who did it with eGFR < 8.16 (66 vs. 61 years, P < 0.001). The association between mortality and eGFR in the crude multivarite Cox model was lost when the model was adjusted by age. In the multivariate Cox model, dialysis initiation period, serum albumin and history of ischemic heart disease were associated with mortality.

CONCLUSION

History of ischemic heart disease, serum albumin and dialysis start before 2005 were risk factors for mortality in ESRD patients. Older age is usually associated with early dialysis initiation, so age adjustment is needed to perform studies aimed to calculate the effect of eGFR at dialysis initiation on survival.

[Kt as control and follow-up of the dose at a hemodialysis unit]

To ensure our patients are receiving an adequate dose in every dialysis session there must be a target to achieve this in the short or medium term. The incorporation during the last years of the ionic dialysance (ID) in the monitors, has provided monitoring of the dialysis dose in real time and in every dialysis session. Lowrie y cols., recommend monitoring the dose with Kt, recommending at least 40 L in women and 45 L in men or individualizing the dose according to the body surface area. The target of this study was to monitor the dose with Kt in every dialysis session for 3 months, and to compare it with the monthly blood test. 51 patients (58% of our hemodialysis unit), 32 men and 19 women, 60.7+/-14 years old, in the hemodialysis programme for 37.7+/-52 months, were dialysed with a monitor with IC. The etiology of their chronic renal failure was: 3 tubulo-interstitial nephropathy, 9 glomerulonephritis, 12 vascular disease, 7 polycystic kidney disease, 7 diabetic nephropathy and 13 unknown. 1,606 sessions were analysed during a 3 month period. Every patient was treated with the usual parameters of dialysis with 2.1 m2 cellulose diacetate (33.3%), 1.9 m2 polisulfone (33.3%) or 1.8 m2 helixone, dialysis time of 263+/-32 minutes, blood flow of 405+/-66, with dialysate flow of 712+/-138 and body weight of 66.7+/-14 kg. Initial ID, final ID and Kt were measured in each session. URR and Kt/V were obtained by means of a monthly blood test. The initial ID was 232+/-41 ml/min, the final ID was 197+/-44 ml/min, the mean of Kt determinations was 56.6+/-14 L, the mean of Kt/V was 1.98+/-0.5 and the mean of URR was 79.2+/-7%. Although all patients were treated with a minimum recommended dose of Kt/V and URR when we used the Kt according to gender, we observed that 31% of patients do not get the minimum dose prescribed (48.1+/-2.4 L), 34.4% of the men and 26.3% of the women. If we use the Kt individualized for the body surface area, we observe that 43.1% of the patients do not get the minimum dose prescribed with 4.6+/-3.4 L less than the dose prescribed. We conclude that the monitoring of dialysis dose with the Kt provides a better discrimination detecting that between 30 and 40% of the patients perhaps do not get an adequate dose for their gender or body surface area.

A coding polymorphism in the 12-lipoxygenase gene is associated to essential hypertension and urinary 12(S)-HETE

The arachidonic acid-derived metabolite 12-(S)hydroxyeicosatetraenoic acid (12(S)-HETE), catalyzed by 12-lipoxygenase (12-LOX, ALOX12), exhibits a variety of biological activities with implications in cardiovascular disease. Previous studies have shown higher urinary excretion of this metabolite in essential hypertension. The aim of this study was to analyze the association of polymorphisms in ALOX12 with hypertension and urinary levels of 12(S)-HETE. We studied 200 patients with essential hypertension (aged 56+/-1 years, mean+/-s.e.m., 97 males) and 166 matched controls (aged 54+/-1 years, 91 males). Out of six polymorphisms in the coding region of ALOX12, only R261Q determined a nonconservative amino-acid change and was evaluated by polymerase chain reaction and restriction digestion. Urinary 12(S)-HETE was measured in Sep-Pack-extracted samples using specific enzyme-linked immunosorbent assay. The distribution of genotypes of the R261Q polymorphism was significantly different between patients and controls: patients 92 (0.46) GG, 84 (0.42) GA, 24 (0.12) AA vs controls 56 (0.34) GG, 78 (0.47) GA, 32 (0.19) AA (P=0.030). On the contrary, no association was observed for two intronic polymorphisms. The urinary excretion of 12(S)-HETE (ng/mg creatinine) was significantly higher in GG homozygous patients (13.0+/-1.5) than in GA (8.2+/-1.8) or in AA (8+/-1.5) patients (P=0.018). These results indicate that a nonsynonymous polymorphism in ALOX12 is associated to essential hypertension and to urinary levels of 12(S)-HETE, thus suggesting a role for this gene in this disease.

[Cytomegalovirus esophagitis in a patient on peritoneal dyalisis]

Symptomatic cytomegalovirus (CMV) infection usually affects immunocompromised patients, such as transplant recipients. From that point of view, the patient with endstage renal disease under maintenance dialysis is considered as immunocompetent. Thus, opportunistic infections, such as CMV infection, is not systematicaly searched in these patients, despite that an impaired cellular immunity has been reported in dialysis patients. We report a case of CMV esophagitis, clinically symptomatic, in a patient endstage renal disease under peritoneal dialysis, without other known immunosuppressive factors and with a good clinical response to gancyclovir treatment.

[Recurrent vascular access trombosis associated with the prothrombin mutation G20210A in a adult patient in haemodialysis]

Vascular access-related complications are a frequent cause of morbidity in haemodialysis patients and generate high costs. We present the case of an adult patient with end-stage renal disease and recurrent vascular access thrombosis associated with the prothrombin mutation G20210A and renal graft intolerance. The clinical expression of this heterozygous gene mutation may have been favoured by inflammatory state, frequent in dialysis patients. In this patient, the inflammatory response associated with the renal graft intolerance would have favored the development of recurrent vascular access thrombosis in a adult heterozygous for prothrombin mutation G20210A. In the case of early dysfunction of haemodialysis vascular access and after ruling out technical problems, it is convenient to carry out a screening for thrombophilia.

Double-blind, placebo-controlled lithium treatment in chemotherapy induced aplasia for AML: reduced antibiotic requirement

A double-blind placebo-controlled study on lithium (Li) therapy after chemotherapy-induced bone marrow aplasia was undertaken in 53 patients with acute myeloblastic leukemia (AML). No difference was observed between the two groups for the duration of aplasia, the number of units of platelets or RBC transfused, the complete remission rate or the disease free survival. However, a statistically significant reduction in the number of days of antibiotic therapy required was found in the treated group (10.55 +/- 2.72 vs 12.73 +/- 3.60, P less than 0.05).