Green Synthesis of Er-Doped ZnO Nanoparticles: An Investigation on the Methylene Blue, Eosin, and Ibuprofen Removal by Photodegradation.

We present a study on the green synthesis of undoped and Er-doped ZnO compounds using Mangifera indica gum (MI). A set of tests were conducted to assess the structure of the material. The tests included X-ray diffraction, Raman, and Fourier-transform infrared spectroscopy. Optical properties were studied using diffuse reflectance and photoluminescence. Morphological and textural investigations were done using SEM images and N2 adsorption/desorption. Furthermore, photocatalytic tests were performed with methylene blue (MB), yellow eosin (EY), and the pharmaceutical drug ibuprofen (IBU) under UV irradiation. The study demonstrated that replacing the stabilizing agent with Mangifera indica gum is an effective method for obtaining ZnO nanoparticles. Additionally, the energy gap of the nanoparticles exhibits a slight reduction in value. Photoluminescence studies showed the presence of zinc vacancies and other defects in both samples. In the photocatalytic test, the sample containing Er3+ exhibited a degradation of 99.7% for methylene blue, 81.2% for yellow eosin, and 52.3% for ibuprofen over 120 min. In the presence of methyl alcohol, the degradation of MB and EY dyes is 16.7% and 55.7%, respectively. This suggests that hydroxyl radicals are responsible for the direct degradation of both dyes. In addition, after the second reuse, the degradation rate for MB was 94.08%, and for EY, it was 82.35%. For the third reuse, the degradation rate for MB was 97.15%, and for EY, it was 17%. These results indicate the significant potential of the new semiconductor in environmental remediation applications from an ecological synthesis.

Facile Synthesis of Ni-Doped ZnO Nanoparticles Using Cashew Gum: Investigation of the Structural, Optical, and Photocatalytic Properties.

This work adopted a green synthesis route using cashew tree gum as a mediating agent to obtain Ni-doped ZnO nanoparticles through the sol-gel method. Structural analysis confirmed the formation of the hexagonal wurtzite phase and distortions in the crystal lattice due to the inclusion of Ni cations, which increased the average crystallite size from 61.9 nm to 81.6 nm. These distortions resulted in the growth of point defects in the structure, which influenced the samples' optical properties, causing slight reductions in the band gaps and significant increases in the Urbach energy. The fitting of the photoluminescence spectra confirmed an increase in the concentration of zinc vacancy defects (VZn) and monovacancies (Vo) as Zn cations were replaced by Ni cations in the ZnO structure. The percentage of VZn defects for the pure compound was 11%, increasing to 40% and 47% for the samples doped with 1% and 3% of Ni cations, respectively. In contrast, the highest percentage of VO defects is recorded for the material with the lowest Ni ions concentration, comprising about 60%. The influence of dopant concentration was also reflected in the photocatalytic performance. Among the samples tested, the Zn0.99Ni0.01O compound presented the best result in MB degradation, reaching an efficiency of 98.4%. Thus, the recovered material underwent reuse tests, revealing an efficiency of 98.2% in dye degradation, confirming the stability of the photocatalyst. Furthermore, the use of different inhibitors indicated that •OH radicals are the main ones involved in removing the pollutant. This work is valuable because it presents an ecological synthesis using cashew gum, a natural polysaccharide that has been little explored in the literature.

Insights into the Antimicrobial Activity of Hydrated Cobaltmolybdate Doped with Copper.

Molybdates are biocidal materials that can be useful in coating surfaces that are susceptible to contamination and the spread of microorganisms. The aim of this work was to investigate the effects of copper doping of hydrated cobalt molybdate, synthesized by the co-precipitation method, on its antibacterial activity and to elucidate the structural and morphological changes caused by the dopant in the material. The synthesized materials were characterized by PXRD, Fourier Transformed Infrared (FTIR), thermogravimetric analysis/differential scanning calorimetry (TG/DSC), and SEM-Energy Dispersive Spectroscopy (SEM-EDS). The antibacterial response of the materials was verified using the Minimum Inhibitory Concentration (MIC) employing the broth microdilution method. The size of the CoMoO4·1.03H2O microparticles gradually increased as the percentage of copper increased, decreasing the energy that is needed to promote the transition from the hydrated to the beta phase and changing the color of material. CoMoO4·1.03H2O obtained better bactericidal performance against the tested strains of Staphylococcus aureus (gram-positive) than Escherichia coli (gram-negative). However, an interesting point was that the use of copper as a doping agent for hydrated cobalt molybdate caused an increase of MIC value in the presence of E. coli and S. aureus strains. The study demonstrates the need for caution in the use of copper as a doping material in biocidal matrices, such as cobalt molybdate.

A novel green approach based on ZnO nanoparticles and polysaccharides for photocatalytic performance.

Novel green photocatalysts based on ZnO in the presence of arabic gum (AGZ) or karaya gum (KGZ) were synthesized by a sol-gel method for photocatalytic performance. The materials were characterized by XRD, FTIR spectroscopy, SEM, nitrogen adsorption/desorption, and PL and diffuse reflectance spectroscopy. Photocatalytic test was performed using methylene blue (MB) dye as the target pollutant under visible light. The reuse of photocatalysts and Artemia saline bioassays were investigated. The ZnO nanoparticles showed a hexagonal structure and the values of the band gaps were 2.95 (AGZ) and 2.98 eV (KGZ). The PL results demonstrated emission bands at 440, 473 or 478 and 549 nm. The textural properties indicated the presence of typically mesoporous materials. The MB discoloration efficiency was 81.5% and 91.0% for AGZ and KGZ, respectively. The photocatalytic activity of AGZ and KGZ was maintained after the third run. The ˙OH radicals are the main species involved in the MB discoloration. The MB discoloration from the photocatalysts showed no toxicity; therefore, they are considered to be promising materials for the degradation of the dye in the photocatalytic process.

[Effect of oxidative stress in patients with chronic renal failure]. / Efecto del tratamiento con hemodiálisis sobre el estrés oxidativo en pacientes con insuficiencia renal crónica.

BACKGROUND: Cardiovascular disease remains the single most common cause of excess morbidity and mortality in end-stage renal disease (ESRD) patients and the traditional risk factors can't explain the high incidence of these events. New "non-traditional" risk factors are analysed in uremic patients and the increased oxidative stress is postulated to be an important contributor to uremic cardiovascular risk. METHODS: In order to evaluate the effects of the hemodialysis treatment, a complete oxidative stress study was performed in fifteen uremic patients. Representative antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), together with oxidized/reduced glutathione ratio (GSSG/GSH) and other oxidation indicators including malondialdehyde (MDA) and 8-oxo-2'-deoxyguanosine (8-oxo-dG), were analysed to assess oxidative stress status in normal control volunteers and in uremic patients treated with hemodialysis (HD). In the latter group blood samples were taken prior and after HD to evaluate the effect of the session of HD over the oxidative markers. RESULTS: Low levels of antioxidant enzyme activities were observed in the uremic patients as compared with normal control subjects. HD treatment results in a significant recovery of these enzyme activities but remain lower as compared with control values. Levels of GSSG and GSH concentrations were increased and reduced respectively in uremic patients. These differences were even higher before the HD and were reduced upon treatment to levels closer to those observed in controls. MDA levels and 8-oxo-dG levels were also increased in uremic patients with the highest values observed in the pre-treated HD group. Even though HD treatment decreases the levels of oxidation products in mononuclear cells of uremic patients the values of the control group are not reached. CONCLUSIONS: Our results suggest that hemodialysis by itself could correct the oxidative status in these patients. The possible mechanisms involved in the oxidative stress changes with the hemodialysis treatment will be discussed below.

[Fungal peritonitis episodes in a peritoneal dialysis centre during a 10-year period: a report of 11 cases]. / Experiencia en peritonitis fúngica en una unidad de diálisis durante diez años.

Fungal peritonitis is a rare cause of peritonitis, but it is associated to poorer prognosis and higher mortality than bacterial peritonitis. Until now, predisposing factors and treatment have not been well established. We retrospectively reviewed all the cases of fungal peritonitis diagnosed for ten years in 218 patients undergoing continuous ambulatory peritoneal dialysis. In all we detected 11 episodes of fungal peritonitis in 11 patients, that means the 4% of continuous ambulatory peritoneal dialysis peritonitis. All the cases of fungal peritonitis were caused by Candida species. As a result of fungal peritonitis 36% of the patients died, 55% had to change to long-term hemodialysis because of failure in peritoneal dialysis technique. Only one case (9%) managed to continue peritoneal dialysis. The factors associated with the development of fungal peritonitis were: the presence of antibiotic use within 1 month before fungal peritonitis, patient older than 70 years old, low levels in albumine plasmatic and long permanence in continuous ambulatory peritoneal dialysis. The treatment consisted in intraperitoneal fluconazol combined with oral 5-flucytosine for 4 to 6 weeks. In the two last cases we associated intravenous caspofungine too. Given that no improvement was seen within 72 hours of treatment, the catheter must be removed in all the cases.

Sepsis and SOFA score: related outcome for critically ill renal patients.

AIMS: To evaluate the influence of sepsis in critically ill patients with acute renal failure (ARF), and to analyze the value of the sequential organ failure assessment (SOFA) score for assessing the morbidity and related mortality of these patients. MATERIAL AND METHODS: A prospective observational study developed in a medical intensive care unit (ICU) of a tertiary care university hospital. Data were collected from January 1, 2001 - July 31, 2002. The inclusion criterion was either a creatinine plasma level > or = 2 mg/dl on ICU admission or increases > or = 30% from its initial value. Sepsis was evaluated at the time of study inclusion, and patients were distributed into 2 groups (septic and nonseptic patients). RESULTS: Two hundred patients with ARF were prospectively enrolled in the study (91 (45.5%) septic and 109 (54.5%) nonseptic patients). Median age was 68 years in septic patients and 72 in nonseptic ones while the percentage of males in both groups was 66% vs 69%, respectively. Septic patients showed more organ failures and more respiratory, cardiovascular and coagulation failures at the time of study admission as well as a worse mean SOFA score during the first 4 days after inclusion (p < 0.01). Mortality rate at the ICU was significantly higher in the septic group when compared to the nonseptic one (55% vs 19.3%, OR = 2.21 (1.65 - 2.97)). Using stepwise logistic regression, acute tubular necrosis and oliguria in septic patients as well as cardiovascular failure (evaluated by SOFA score) in nonseptic patients were identified as independent risk factors for mortality. CONCLUSIONS: Septic and nonseptic ICU patients with ARF have an increased risk of ICU mortality depending on the type of organ failure. Although SOFA score does not predict outcome, it is a useful tool to categorize these patients and to describe a sequence of complications in critically ill patients.

[Acute renal failure in critically ill patients. A prospective epidemiological study]. / Fracaso renal agudo en la unidad de cuidados intensivos. Estudio observacional prospectivo.

AIMS: To determine factors which may predict mortality in patients admitted to intensive care unit who present acute renal failure. METHODS: Prospective observational study of the patients admitted to a multidisciplinary intensive care unit over a year. The inclusion criteria were a creatinine plasmatic value > or = 2 mg/dl (177 micromol/l) or an increase (30% or higher) of its basal value on admittance. RESULTS: One hundred and twenty-seven patients (age = 65.83 +/- 15.06 years; 38% male) with acute renal failure, were prospectively enrolled in the study (13% of intensive care unit admissions). The univariate analysis showed that hospital origin, acute tubular necrosis, late ARF, oliguria, maintained hypotension, sedation or coma, oncological disease and need of mechanical ventilation were significantly associated with mortality (p < 0.05). This association was also found for sepsis (OR: 41.5), multiorganic failure (OR: 3.58) and respiratory, cardiovascular or haematological failure according to the SOFA score. The multivariate analysis found that four clinical variables had an independent predictive value for mortality risk: acute tubular necrosis [OR: 4.57 (2.32-9.00)], use of vasoactive drugs [OR: 2.32 (1.22-4.40)], oliguria [OR: 2.15 (1.12-4.13)] and the acute renal failure starting during admission [OR: 2.06 (1.09-3.88)]. CONCLUSION: Data related to renal failure have worse prognosis than other demographic or clinical data in critically ill patients with acute renal failure. Multicentric studies with unified criteria are needed to analyse the most important prognostic factors.

[Risk factors associated with survival in patients in a peritoneal dialysis program]. / Factores de riesgo asociados con la supervivencia en pacientes en programa de diálisis peritoneal.

The aim of this study was to quantify the effect of different mortality risk factors in peritoneal dialysis and to establish a prognostic index that could predict mortality risk when patients start dialysis. A prospective study was performed on 103 patients included in our peritoneal dialysis program. The mean follow-up time was 26 +/- 21 months. A multivariate analysis (Cox regression was made to identify different risk factors that could influence patient survival during peritoneal dialysis. Age, gender, parathyroid hormone, albumin, cholesterol, and the presence of diabetes mellitus were evaluated as potential risk factors. Patients were distributed in three groups (high, medium and low risk), according to the risk factors with a significant influence in multivariate analysis, and patient survival was studied depending on the prognostic index using Kaplan-Meier estimator. Overall patient survival was 90% (95%CI: 83 to 96%) after the first year and 40% (95%IC: 32 to 58%) after 5 years of follow-up. The Cox regression analysis identified albumin below 4 g/dL (RR: 2.57; 95% CI: 1.16 to 5.72), age older than 65 years RR: 3.10; 95%IC: 1.20 to 7.98) and diabetes mellitus (relative risk, RR: 4.36; 95%IC: 1.43 to 13.31) as independent risk factors for mortality in patients receiving peritoneal dialysis. Patient survival after two years was 40% (95%IC: 31 to 59%), 73% (95%IC: 60 a 86%) and 100% (p < 0.05), respectively. Malnutrition and related factors in patients receiving peritoneal dialysis are associated with a higher mortality rate.

Plasma Brain Natriuretic Peptide Levels in Cardiac Function Assessment in Chronic Dialysis Patients.

BACKGROUND: Brain natriuretic peptide (BNP) is elevated in patients with end-stage renal disease and could reflect left ventricular dysfunction. AIM: To evaluate the plasma levels of BNP in two groups of asymptomatic patients on different dialysis programs and to correlate their variations with echocardiographic parameters. METHODS: Group A consisted of 36 patients on chronic hemodialysis (HD), and group B included 38 patients on continuous ambulatory peritoneal dialysis (CAPD). ECG and echocardiography were performed, and concomitantly plasma BNP levels were determined before and after a regular 4-hour session in HD patients and before performing a dialysate exchange in patients on CAPD. RESULTS: BNP values in group A were found to be higher than in group B (419 ± 76 vs. 193 ± 56 pg/ml; p < 0.03). The cutoff point which discriminated both groups was 194 pg/ml (sensitivity: 64% and specificity: 76%; p = 0.001). Significant differences were found with respect to the following echocardiographic data (group A vs. group B): left atrial (LA) size (40 ± 13 vs. 34 ± 1 mm), LA volume (59 ± 16 vs. 41 ± 32 ml), transmitral flow E/A (1.17 ± 0.01 vs. 0.9 ± 0.06), the movement of the mitral valve annulus e/a (tissue Doppler imaging; 1.19 ± 0.15 vs. 1.05 ± 0.13) and left ventricular mass index (133 ± 10 vs. 108 ± 11). CONCLUSION: Patients on CAPD had lower levels of BNP, and echocardiographic findings indicated decreased volume overload. In asymptomatic patients, marked increases in BNP levels may reflect early stages of pathological processes that precede the development of apparent cardiac manifestations (left ventricular hypertrophy). Only echocardiographic parameters of cardiac dysfunction should be used as diagnostic criteria.

Importance of residual renal function in continuous ambulatory peritoneal dialysis: its influence on different parameters of renal replacement treatment.

OBJECTIVE: To study the influence of residual renal function (RRF) on different parameters of the renal substitutive treatment offered by peritoneal dialysis. METHODS: We analyzed the impact of RRF on dialysis dose, nutrition parameters, anemia and phosphocalcic metabolism in 37 patients with end-stage renal disease (ESRD) treated by continuous ambulatory peritoneal dialysis (CAPD). Analytical controls were done every 6 months after an initial assessment at the end of the first month of treatment. Multiple lineal regression models were used as the statistical method to analyze the influence of RRF on different theoretically dependent factors. RRF was calculated as a mean of creatinine and urea clearances. Three observations per patient were used: one at the end of the first month of treatment; a final one at the end of follow-up (mean time 24.2 +/- 11.4 months), and at a mean time between them (13.4 +/- 6.7 months), with a final number of 111 observations. RESULTS: Dialysis dose: RRF was the most important factor in terms of creatinine clearance (r(2) = 0.94; beta = 0.999), KT/V (r(2) = 0. 68; beta = 0.819) and beta(2)-microglobulin levels (r(2) = 0.46; beta = -0.489). Nutrition parameters: RRF was a determinant factor for normalized protein catabolic rate (r(2) = 0.53; beta = 0.471), percent lean body mass (r(2) = 0.45; beta = 0.446) and albumin levels (r(2) = 0.25; beta = 0.229). Anemia: RRF was the most important factor when studying hemoglobin levels (r(2) = 0.28; beta = 0.407). Phosphocalcic metabolism: Between the analyzed factors, RRF was the only one which reached significance on serum phosphate levels (r(2) = 0.19; beta = -0.594). RRF did not show any relationship with either calcium or PTH levels. CONCLUSIONS: Independent of other factors, RRF in CAPD is positively and directly related to dialysis dose, beta(2)-microglobulin levels, nutrition parameters (albumin, normalized protein catabolic rate and percent lean body mass, hemoglobin and serum phosphate levels.

Prevalence and risk factors for hepatitis C virus infection in continuous ambulatory peritoneal dialysis patients.

BACKGROUND: Studies on hepatitis C virus antibodies (Anti-HCV) in CAPD patients are scarce and include a small number of patients. Nevertheless, risk factors related to Anti-HCV in these patients are still subject to controversy. Purpose of the study. To analyse the incidence and risk factors associated with the presence of Anti-HCV in CAPD patients. METHODS: We studied 255 patients from five different treatment centres of our region. The analysis was repeated after excluding 161 patients who had previously received haemodialysis treatment at least once. Anti-HCV testing was made by the 2nd-generation ELISA: As a supplementary test we used RIBA-4 in three centers and INNOLIA in the other two. Risk factors were analysed using logistic regression model for multivariate analysis. RESULTS: In the whole group, 29 patients (11.4%) were anti-HCV positive. Logistic regression analysis determined the following variables as independent risk factors: hepatitis previous to CAPD (P<0.001, odds ratio (OR):44.9), Anti HBc positivity (P=0.019, OR:9. 24), blood transfusions previous to CAPD (P=0.015, OR:1.05) and CAPD duration were excluded, the prevalence of HCV antibodies was 8.5% (8/94). In this group multivariate analysis showed that Anti-HCV positivity correlated with hepatitis previous to CAPD (P<0.0003, OR: 126) and Anti HBc positivity (P=0.002, OR:41.9). CONCLUSIONS: Our prevalence of hepatitis C virus (HCV) infection in CAPD patients was lower than other renal replacement therapy modalities, and correlated to events occurring mainly before starting CAPD treatment. This technique could be considered as low risk for HCV infection.

Diálisis peritoneal en pacientes diabéticos: indicaciones, ventajas y posibles complicaciones / Peritoneal dialysis in diabetic patients: indications, advantages and possible complications

La diálisis peritoneal surge como una alternativa a la hemodiálisis. Utiliza el propio peritoneo como membrana dialítica y su práctica es sencilla. Tras realizar un acceso permanente a la cavidad abdominal, se instilan las soluciones prefijadas con un volumen y una permanencia adecuados. Existen diferentes procedimientos, siendo los regímenes continuos los más empleados. La mayoría de pacientes pueden realizar la técnica, ya que las contraindicaciones son escasas. No precisa de acceso vascular y proporciona mayor estabilidad hemodinámica que la hemodiálisis. Por otro lado, la sobrecarga de glucosa puede empeorar el control glucémico, aunque la administración intraperitoneal de insulina parece disminuir este efecto. En el paciente diabético es aconsejable un inicio precoz de la terapia sustitutiva. En estudios a largo plazo, la supervivencia del paciente es como mínimo superponible a la de los pacientes en hemodiálisis. Sin embargo, la supervivencia de la técnica en general es menor, si bien no suelen existir diferencias hasta pasados 5 años. En resumen, en los pacientes diabéticos la diálisis peritoneal ofrece igual o mejor supervivencia que la hemodiálisis, sobre todo en los años iniciales del tratamiento(AU)

Peritoneal dialysis arises as an alternative to hemodialysis. It uses the patient’s own peritoneum as a dialytic membrane and its practice is simple. After creating permanent access to the abdominal cavity, fixed solutions with suitable volume and appropriate length of time are instilled. There are different perfusion regimens, being the continuous the most popular. Most patients can use the technique because contraindications are infrequent. Vascular access is not needed, and greater hemodynamic stability than hemodialysis is provided. On the other hand, glucose overload may deteriorate glycemic control, although intraperitoneal insuline may diminish this effect. In the diabetic patient it is advisable promptly start substitute therapy. Long term studies show patient survival of at least that of haemodialysis patients. However, the survival of the technique is usually shorter, showing no differences until after 5 years of treatment. In summary, in diabetic patients, peritoneal dialysis lead to similar or even better survival than hemodialysis, specially in the first years of treatment(AU)