Improving knowledge about permeability in membrane bioreactors through sensitivity analysis using artificial neural networks.

Membrane bioreactor (MBR) has been widely employed for industrial effluent treatment, as its higher efficiency in removing pollutants makes effluent reuse more feasible. However, membrane fouling remains as a limiting factor for its greater diffusion. This work performed a sensitivity analysis study to investigate the effects of analytical and operating variables on membrane permeability. The case study is a MBR treating oil refinery effluents. After the identification and validation of a predictive neural model for permeability, sensitivity analysis methods based on both connection weights and variable disturbances were used to quantify and rank the variables influence. A comprehensive analysis showed that Suspended solids and Days between cleanings exerted greater effects on permeability, whereas sludge filterability and sludge temperature were less significant. In sequence, a specific analysis revealed distinct dynamics in MBR operation given different solids concentrations. For instance, from higher solids concentrations, among all the evaluated parameters, only COD presented low significance to the permeability. This evidence suggests that permeability is more susceptible to variations when operating with higher concentrations of Suspended solids. The global result of this study contributes to more efficient MBR operations since distinct relations with permeability imply different effects on membrane fouling.

Performance evaluation of startup for a yeast membrane bioreactor (MBRy) treating landfill leachate.

The startup process of a membrane bioreactor inoculated with yeast biomass (Saccharomyces cerevisiae) and used in the treatment of landfill leachate was evaluated. The yeast membrane bioreactor (MBRy) was inoculated with an exogenous inoculum, a granulated active dry commercial bakers' yeast. The MBRy was successfully started up with a progressive increase in the landfill leachate percentage in the MBRy feed and the use of Sabouraud Dextrose Broth. The membrane plays an important role in the startup phase because of its full biomass retention and removal of organic matter. MBRy is a suitable and promising process to treat recalcitrant landfill leachate. After the acclimation period, the COD and NH3 removal efficiency reached values of 72 ± 3% and 39 ± 2% respectively. MBRy shows a low membrane-fouling potential. The membrane fouling was influenced by soluble microbial products, extracellular polymeric substances, sludge particle size, and colloidal dissolved organic carbon.

Concomitant unipolar radiofrequency ablation of nonparoxysmal atrial fibrillation in rheumatic and degenerative valve disease.

OBJECTIVES: The aim of this study was to compare the results of concomitant unipolar radiofrequency ablation of nonparoxysmal atrial fibrillation (AF) between rheumatic and degenerative valve disease (RHD versus DVD). METHODS: Between 2005 and 2012, 96 patients underwent AF ablation with unipolar radiofrequency concurrently with heart valve surgery. They were followed in three months and at a median follow-up of 39 (18 to 61) months. RESULTS: The mean age was 62 years old. Most patients had RHD (54.2%) and dilated left atria (LA, diameter 52.6 ± 5.8 mm). Patients with RHD were more likely to be younger and have larger LA. 88 patients (92%) underwent prophylactic closure of the left atrial appendage (LAA). Pulmonary vein-isolation, box lesion, LAA isolation, and left isthmus line were performed by radiofrequency, along with other right atrial cut-and-sew lines. Overall, surgical complications occurred in 25% of the patients and pacemaker implantation (17.7%) was the most frequently observed. In-hospital mortality rate was zero. The median length of stay was 8 (7, 12) days. Seventy-one percent of the patients were in sinus rhythm at discharge. Sinus rhythm maintenance was 45% and 40% in three months and at a median follow-up of 39 (18 to 61) months (269 patient-years), respectively. There was no statistically significant difference between RHD and DVD. In the multivariate analysis, LA ≥50 mm was the single independent predictor of AF recurrence at three months. CONCLUSIONS: Radiofrequency ablation of AF concurrently with heart valve surgery is poorly effective in patients with multiple adverse risk factors. Patients with RHD and DVD had similar rates of sinus rhythm recovery. LA ≥50 mm was the single predictor of AF recurrence at three months.

Surgical treatment of atrial fibrillation: an updated review.

The first Cox-maze procedure was performed in 1987, demonstrating the feasibility of a non-pharmacological treatment for atrial fibrillation (AF). Since then, surgery for AF has changed over time, in parallel with technological advances. Replacement of surgical incisions with linear ablation lines made a previously cumbersome procedure accessible to most surgeons, without compromising success. On the other hand, new ablation technologies paved the way for the development of minimally invasive surgery, which may potentially extend the scope of surgery to patients who would otherwise be deemed unsuitable. Nonetheless, literature on minimally invasive surgery is still scarce and randomized clinical trials currently under way are expected to shed light on some controversial issues. Moreover, successful AF treatment will probably rely on close collaboration between surgery and electrophysiology. Indeed, the hybrid procedure, though still in its very beginning, seems to combine the best of catheter and surgical ablation. However, further studies are warranted to determine the effectiveness of this promising strategy, especially in patients with persistent and longstanding persistent AF. Better understanding of AF pathophysiology as well as more accurate preoperative localization of AF triggers will bring about the possibility of tailoring specific lesion sets and ablation modalities to individual patients. This, in turn, will increase recovery and maintenance of sinus rhythm, with significant benefits in long-term outcomes.

Radiofrequency ablation of atrial fibrillation during concomitant cardiac surgery.

OBJECTIVES: We present the experience of our centre with radiofrequency ablation of atrial fibrillation concomitantly with cardiac surgery Methods: 170 patients underwent atrial fibrillation ablation with uni/bipolar-radiofrequency. They were followed for 3-months and then as appropriate for the cardiac disease. In 2013, patients still alive underwent rhythm monitoring with ECG and 24-hour tape if in sinus rhythm RESULTS: Mean age was 65 years old and 42% of the patients were male. Paroxysmal AF was rare (7%). Most patients had preserved ejection fraction and dilated left atria (diameter 53.2±7.5 mm). The most common indication for cardiac surgery was valve disease. More than 75% of the patients underwent prophylactic closure of the left atrial appendage. Pulmonary vein isolation was performed in all patients, followed by other left atrial ablation lines. Overall, surgical complications were rare, being the most frequent pacemaker implantation (15%). Median length of stay was 9 days (p25-p75:7-14). At discharge, 69% of the patients were in sinus rhythm, being 90% on anticoagulation and 69% on amiodarone. In-hospital mortality was less than 3% (5 patients), none of them related to the ablation procedure. At 3 months, 50% of the patients were in sinus rhythm, being 92% on anticoagulation and 75% on antiarrhythmic drugs. Direct current cardioversion was successful in 8 of 12 patients. In the multivariate analysis, being in sinus rhythm at discharge was the single independent predictor of maintaining sinus rhythm at 3 months. In 2013 (469 patients-year), 40% of the patients were in sinus rhythm, being 80% on anticoagulation and 45% on antiarrhythmic drugs. CONCLUSIONS: Concurrent atrial fibrillation ablation with radiofrequency achieves satisfactory and stable recovery of sinu rhythm without adding significant operative risk and post-operative complications.

Recovery coefficients determination for partial volume effect correction in oncological PET/CT images considering the effect of activity outside the field of view.

OBJECTIVES: The partial volume effect (PVE) has a great impact in quantitative PET/CT imaging. Correction methods have been recently proposed by many authors to make the image quantification more accurate. This work presents a methodology for determining the recovery coefficients (RCs) for PVE correction in PET/CT images. It was taken into account the radioactivity outside the field of view (FOV), which is expected in a patient image acquisition. METHODS: The NEMA image quality phantom and the NEMA scatter phantom were used. The phantoms were filled with (18)F-FDG for different sphere-to-background ratios. The RCs have been determined from image acquisitions in a Siemens Biograph 16 Hi-Rez PET/CT scanner with and without the scatter phantom. RESULTS: The RC values that ranged from 0.38 to 1.00 without the scatter phantom exhibited a wider variation when this latter was taken into account (from 0.27 to 1.02). This more realistic estimation must be considered if one takes into account that an incorrect SUV measure in tumors leads to errors in the evaluation of the response to therapy based on PET/CT images. CONCLUSIONS: The activity outside the FOV should be considered in RCs determination to improve the RC-based PVE correction method.

Tratamento endoscópico do Enfisema: uma atualização / Bronchoscopic Treatment of Emphysema: an Update

O objetivo desta revisão foi apresentar uma atualização das alternativas endoscópicas utilizadas no tratamento do enfisema pulmonar. Os mecanismos bloqueadores de fluxo (válvulas) permanecem como os únicos dispositivos aprovados para uso clínico no tratamento do enfisema pulmonar na América do Sul. A válvula endobrônquica Zephyr® representa o método broncoscópico para o tratamento do enfisema mais bem estudado até o momento, e seu uso clínico está autorizado em diversos países da Europa, Ásia e América do Sul. A válvula IBV® obteve aprovação para uso no tratamento de fuga aérea prolongada nos EUA. Os critérios mais frequentemente analisados na indicação de tratamento endoscópico, além dos aspectos clínicos, incluem o aprisionamento dinâmico, a heterogeneidade e a ventilação colateral, em especial, a passagem de ar através das cissuras interlobares. Atualmente, há softwares que permitem a medida precisa da heterogeneidade e da integridade da cissura.Os resultados obtidos em diversas séries de casos e alguns ensaios randomizados têm trazido nova luz ao entendimento da fisiopatologia dessa doença. No entanto, ainda há necessidade de mais estudos randomizados utilizando o conhecimento adquirido até o momento

The objective of this review is to present an update on endoscopic alternatives for the treatment of emphysema.One-way endobronchial valves continue to be the only devices approved for clinical use in the treatment of emphysema inSouth America. The use of the Zephyr® endobronchial valve is currently the most widely studied bronchoscopic method fortreatment of emphysema and has been approved for clinical use in several countries in Europe, Asia, and South America. Another valve, the IBV® valve, has been approved for use in the treatment of persistent air leaks in the United States. In additionto clinical features, the criteria most often analyzed for indicating endoscopic treatment are dynamic hyperinflation, heterogeneity, and collateral ventilation, especially the passage of air through the interlobar fissures. Currently, there is softwarecapable of accurately measuring heterogeneity and fissure integrity.The results obtained in various case series and certain randomized trials have shed new light on the pathophysiology of emphysema. However, additional randomized trials using the knowledge gained thus far are warranted in order to furtherevaluate this procedure

Tratamento endoscópico do enfisema / Bronchoscopic treatment of emphysema

O objetivo do presente estudo foi apresentar as alternativas endoscópicas para o tratamento do enfisema pulmonar. Os tratamentos incluem o remodelamento com cola biológica e vapor, mecanismos bloqueadores do fluxo aéreo (válvulas) e mecanismos não bloqueadores (coils). A principal diferença entre o remodelamento e os dispositivos (bloqueadores ou não) é que o remodelamento é definitivo, enquanto válvulas e coils podem ser retirados e substituídos. Até o momento, somente válvulas foram aprovadas para uso clínico na América do Sul. Os fatores mais significativos para selecionar pacientes para os diversos tratamentos não cirúrgicos, além dos aspectos clínicos, são o aprisionamento dinâmico, a heterogeneidade e a ventilação colateral. A broncoscopia virtual tem um papel importante no planejamento do tratamento endoscópico do enfisema, diminuindo o tempo do procedimento. Tendo em vista as dúvidas que permanecem acerca dos mecanismos fisiopatológicos de melhora dos pacientes e dos critérios de seleção dos mesmos, é fundamental estabelecer protocolos para o emprego dessas técnicas. Também são necessárias meta-análises para interpretar os resultados já descritos na literatura, assim como estudos randomizados de grande porte que levem em conta os conhecimentos adquiridos até o momento.

The objective of this review is to present endoscopic alternatives for the treatment of emphysema. Treatments include tissue remodeling with biological glue or thermal vapor; airflow blocking mechanisms (valves); and nonblockingmechanisms (coils). The main difference between the remodeling technique and the use of (blocking or non-blocking)devices is that remodeling is definitive, whereas valves and coils can be removed and replaced. In South America, only valve implants have been approved for clinical use. In addition to clinical features, the major criteria for selecting patients for nonsurgical treatment are dynamic hyperinflation, heterogeneity, and collateral ventilation. Virtual bronchoscopy, which reduces the procedure time, plays an important role in the planning of endoscopic treatment for emphysema. Questions remain regarding patient selection criteria and the pathophysiological mechanisms leading to improvement. It is therefore essential to establish guidelines for the use of this technology. Meta-analyses interpreting the results described inthe literature, as well as large randomized trials of the various techniques, should also be conducted to further evaluate this procedure.

[Oxidative stress and its effects on insulin resistance and pancreatic beta-cells dysfunction: relationship with type 2 diabetes mellitus complications]. / Stress oxidativo e seus efeitos na insulino-resistência e disfunção das células Beta-pancreáticas: relação com as complicações da diabetes mellitus tipo 2.

Type 2 diabetes mellitus, the most prevalent and serious metabolic disease worldwide, is believed to result from the interaction between genetical and lifestyle factors. In genetically predisposed people, the combination of a hypercaloric ingestion and reduced physical activity is responsible for the appearance of insulin resistance. This state can be overcomed, until a certain point, with increments of insulin secretion (hyperinsulinemia). However, an insufficient compensation leads to a state of glucose intolerance, which can evolve to diabetes, according to actual knowledge. The noxious effects of the hyperglycemia, allied with the possible increase of free fatty acids, are mediated by highly reactive molecules, oxygen and nitrogen free radicals species (ROS and RNS). Recent data suggests that these reactive species are signalling molecules and are involved in the regulation of the cellular function, being its increased production or reduced elimination a cause of oxidative stress. Indeed, those free radicals act directly through oxidative damage on macromolecules (proteins, lipids, DNA) or indirectly, activating single transduction pathways sensible to stress mechanisms. In this review, we will consider the pathways recognized as the more significant in stress mechanisms, namely: NF-kB, JNK/SAPK, p38 MAPK, PKC, AGE/RAGE, hexosamines and poliol. These signalling cascades are believed to be responsible for the insulin resistance and reduced insulin secretion, therefore the use of innocuous antioxidant substances such as vitamin C, E and the a-lipoic acid, is seen as a possible step for type 2 diabetic complications management. We will also discuss acetylsalicylic acid potentialities in the above-mentioned pathologies.

Ghrelin reverses molecular, structural and hemodynamic alterations of the right ventricle in pulmonary hypertension.

Ghrelin is an endogenous peptide that has a dual effect by activating specific receptors and by stimulating release of growth hormone. There is increasing evidence that ghrelin has a potent vasodilator effect. Recently, we demonstrated that exogenous administration of ghrelin modulates its endogenous levels and attenuates the majority of alterations induced by monocrotaline (MCT). In the present study, we evaluate the effects of chronic administration of ghrelin on hemodynamic and morphometric parameters of the right ventricle, as well as on myocardial levels of SERCA2a and endothelin-1. Adult Wistar rats were injected with MCT (60 mg/kg, sc) or just the vehicle (day 0). One week later, the animals treated with MCT were randomly divided into two groups and treated with ghrelin (100 microg/kg, bid, sc) or with a similar volume of vehicle. Between days 21-25 the animals were instrumented to record right ventricular (RV) pressures and samples were collected for morphological and molecular analysis. Ghrelin treatment attenuated the effects of MCT, namely: RV myocyte fiber diameter, pulmonary vascular remodeling (evaluated by % medial wall thickness of peripheral arteries), RV peak systolic pressure, RV end-diastolic pressure, time constant tau, and SERCA2a and endothelin-1 mRNA levels. Chronic ghrelin administration attenuates MCT-induced pulmonary hypertension, vascular remodeling and RV hypertrophy. These results suggest a potential therapeutic role for the ghrelin-growth hormone axis in pulmonary hypertension.

Avaliação de 166 ETEs em operação no país, compreendendo diversas tecnologias. Parte 1: análise de desempenho / Evaluation of 166 treatment plants operating in Brazil, comprising several technologies. Part 1: performance analysis

O trabalho apresenta uma análise de desempenho de 166 estações de tratamento de esgotos urbanos em operação nos estados de Minas Gerais e de São Paulo. Foram investigadas seis modalidades de tratamento diferentes, compreendendo os processos: (a) fossa séptica seguida de filtro anaeróbio, (b) lagoas facultativas, (c) lagoas anaeróbias seguidas por lagoas facultativas, (d) lodos ativados, (e) reatores UASB operando isoladamente e (f) reatores UASB seguidos por pós-tratamento. A avaliação considerou as concentrações efluentes e as eficiências de remoção dos constituintes DBO, DQO, SST, NTK, PT e coliformes (organismos termotolerantes), que foram comparadas com valores típicos reportados na literatura técnica. Em geral, o desempenho na remoção de matéria orgânica esteve dentro do esperado. As eficiências de remoção de SST estiveram abaixo, enquanto a remoção de coliformes foi maior que a descrita na literatura. A remoção de nutrientes foi baixa, já que nenhuma das modalidades analisadas foi projetada com este objetivo.

Avaliação de 166 ETES em operação no país, compreendendo diversas tecnologias. Parte 2: influência de fatores de projeto e operação / Evaluation of 166 treatment plants operating in Brazil, comprising several technologies. Part 2: the influence of design and operational parameters

O estudo avalia a influência de fatores de projeto e de operação no desempenho de estações de tratamento de esgotos, considerando a concentração efluente e eficiência de remoção de DBO. Apenas quatro das seis tecnologias de tratamento estudadas na Parte 1 forneceram dados suficientes para análise: lagoas facultativas, lagoas anaeróbias seguidas por lagoas facultativas, lodos ativados e reatores UASB operando isoladamente. O objetivo da pesquisa foi verificar a influência das condições de carga (sobrecarga, carga adequada e subcarga), do porte da estação e do envolvimento operacional (tendo como indicador a freqüência de monitoramento) no desempenho das estações de tratamento. Os resultados mostraram que não existe uma relação consistente entre a eficiência de remoção e as variáveis operacionais. A contribuição e a influência de cada variável difere de ETE para ETE, e pode ser resultado de projeto, operação ou ambos.