High-resolution multivariate analysis of the hydrochemical signature of water corridors in the upper Río de la Plata estuary, Argentina.

Major world river-estuaries integrate the hydrochemical characteristics of the basin with specific signatures which are maintained until complete mixing or discharge to the sea. The chemical signature of distinct water masses and the anthropogenic impact in the Upper Río de la Plata estuary (RLP) were evaluated by high-resolution continuous monitoring (i.e. every 200 m) of conductivity, turbidity, pH, temperature, chlorophyll a and coloured dissolved organic matter (CDOM), discrete analysis of suspended particulate matter (SPM) grain size composition combined with multivariate analysis (K-means clustering, Principal Component Analysis). The characteristic signatures of main RLP tributaries such as the Paraná River, yielding higher conductivity, CDOM, turbidity and coarser SPM, and the Uruguay River, with clearer, more eutrophic waters enriched in very fine SPM, were maintained 60 km seaward from the estuary head. Across the river, three water corridors with distinct signatures and variable widths (3-20 km) were identified reflecting the transition from Paraná to Uruguay River waters. Multivariate techniques also allowed the identification of a polluted coastal corridor (higher conductivity and CDOM and lower turbidity) impacted by wastewater discharges from the metropolitan Buenos Aires and La Plata cities extending 100 km seaward. The combined strategy of high-resolution monitoring, discrete sampling and multivariate techniques was a useful tool to identify water masses, corridors of flow and anthropogenic sources in a heavily urbanized estuary.

Prevalence of Chlamydia trachomatis, Ureaplasma urealyticum, and Neisseria gonorrhoeae in Asymptomatic Women from Urban-Peripheral and Rural Populations of Cuenca, Ecuador.

BACKGROUND: Sexually transmitted diseases (STDs) are a serious public health issue due to their high prevalence and a substantial percentage of women being asymptomatic. The present study aimed to determine the prevalence of three STD-causative pathogens in asymptomatic women from Southern Ecuador, with the ultimate purpose of updating the epidemiological data and obtaining a timely diagnosis, which can prevent further complications. METHODS: This cross-sectional study included 102 asymptomatic women from Cuenca, Ecuador, who underwent a cervical cytology examination. They met all the inclusion criteria and signed the consent form. Nucleic acids were extracted from each sample, and PCR and flow-through hybridization were performed to detect the pathogens responsible for three STDs. Descriptive and inferential statistics were used to define and describe the study population, obtain the frequency data, and measure central tendencies to determine possible associations among the variables. RESULTS: We found that 49.02% of the participants were infected with at least one of the three microorganisms, with 48.04% and 2.94% carrying Ureaplasma urealyticum (UU) and Chlamydia trachomatis (CT), respectively. Neisseria gonorrhoeae (NG) infection was not observed. Among the participants, 1.96% presented co-infections with CT and UU. Approximately half of the participants presented with asymptomatic infections caused by at least one microorganism. CONCLUSIONS: This study demonstrates the importance of conducting regular STD screening programs for high-risk asymptomatic women.

Characterization, in vitro dissolution, and pharmacokinetics of different batches of efavirenz raw materials.

OBJECTIVE: To perform the solid-state characterization and the in vitro-in vivo correlation (IVIVC) of three batches of efavirenz (EFV) active pharmaceutical ingredients. SIGNIFICANCE: EFV is an effective anti-HIV drug. Due to the poor aqueous solubility, the rate and extent of EFV absorption deeply depend on its dissolution characteristics. METHODS: Thermal analyses, x-ray diffraction, and particle size distribution were performed. The saturation solubility and dissolution profiles were assessed in 0.5% (w/v) sodium lauryl sulfate (SLS), fasted-state simulated intestinal fluid (FaSSIF), and fed-state simulated intestinal fluid (FeSSIF) using a flow-through cell. Each batch was orally administered to Wistar rats and the pharmacokinetic parameters were correlated with those obtained from in vitro dissolution. RESULTS: All batches of EFV consisted polymorph I. EFV-A presented the lowest particle size distribution [d(v,0.5) = 197.8 µm; d(v,0.9) = 444.6 µm] followed by EFV-B [d(v,0.5) = 223.9 µm; d(v,0.9) = 481.1 µm], and EFV-C [d(v,0.5) = 240.8 µm; d(v,0.9) = 497.3 µm]. The saturated solubility in FaSSIF was 36% and 40% of that in FeSSIF and SLS, respectively. EFV-A presented the fastest rate and largest extension of dissolution than EFV-B and C (79.15%, 69.93% and 54.22%, respectively, as well as the highest maximum plasma concentration. Levels B, C, and multiple-C of IVIVC models were achieved. CONCLUSION: The FaSSIF medium discriminated the dissolution profiles of EFV APIs. Small differences in particle size distribution had a significant impact on the biopharmaceutical parameters of EFV, suggesting that strict control of such parameter is an important aspect during API development and drug formulation.

Nitrogen dynamic in vitro using sludge of a sewage stabilization pond from Patagonia (Argentina).

A relevant and current aspect of wastewater treatment systems is related to the processes of the nitrogen cycle that results in its elimination in gaseous forms. In the present study, we report the first measurements of nitrate-reducing rate (NRR) at lab-scale, using the flow-through reactor technique with sludge of a sewage stabilization pond system located in Patagonia (Argentina). Sludge was collected from Inlet and Outlet areas, in winter and summer. The sludge was characterized by having high moisture content (>94%) and organic matter concentration greater than 37%. The nitrate reduction experimental dates fitted significantly to the Michaelis-Menten model, allowing the estimation of the parameters that regulate the NR kinetics. The maximum potential nitrate reduction rate (Rmax) showed great variability, registering a maximum of 131.6 µmol-N·gdw-1·h-1 (Outlet-Summer) and a minimum of 4.1 µmol-N·gdw-1·h-1 (Inlet-Winter). The lowest half saturation constant (Km) was recorded in the Inlet sludge during the winter (6.1 mg N-NO3-·L-1), which indicates a greater affinity for nitrate of this bacterial consortium. An unusually high activity of NR was registered, being higher with sludge from the Outlet zone and with summer temperature. In full-scale ponds, the NR activity could explain a relevant part of the nitrogen removal that involves the escape of gaseous forms.

Deposition of graphene nanoparticles associated with tannic acid in microfiltration membrane for removal of food colouring.

A modified microfiltration (MF) membrane was prepared by flow-through coating method. First the sulfuric acid solution was vacuum filtered on the polyethersulfone (PES) MF membrane, providing the introduction of a sulfonic acid group to the backbone of PES. Sequentially, the polyethyleneimine solution was vacuum filtered to provide amine groups on the membrane surface. Finally, the graphene oxide solution, functionalized with different masses of tannic acid, was vacuum filtered on the membrane surface, producing the cross-linked modified membranes. These were efficient in the removal of anionic food colouring, achieving high removal rates and low fouling, compared to unmodified membrane. The best membrane in terms of bright blue dye removal was the MF PEI5GO1TA4, capable of removing all the feed solution, and demonstrating its possibility of reuse in five cycles of operation.

Layered platforms of Ti4O7 as flow-through anodes for intensifying the electro-oxidation of bentazon.

In this study, we prepared Ti4O7 porous electrodes with continuous layered structures characterized by different layer-to-layer distance (from 2 to 10 µm) but the same total void fraction (88-90%), to modulate the electrodes' permeability and the volumetric electrochemical surface area (from 90 to 840 cm2 cm-3). These platforms were evaluated as anodes in the electro-oxidation (EO) of bentazon in a three-electrode cell under galvanostatic conditions, operated both in traditional batch (TB) or batch recycle flow-through (BRFT) modes. The performance was significantly enhanced when the liquid was recirculated through the lamellar structure of the electrodes. In BRFT mode, the electrode interlayer gap was found to be a key factor to control the bentazon and total organic carbon (TOC) conversions. For the best conditions evaluated (BRFT, 10 µm-interlayered Ti4O7 electrodes with a volumetric surface area of 90 cm2 cm-3), the effect of the applied current (1 or 3 mA) and liquid flow rate (10, 12 or 14 mL. min-1) was investigated. Specific energy consumption (SEC) values were estimated to reveal the performance of each of the EO treatments from an energetic point of view. The use of 10 µm-interlayered Ti4O7 electrodes at 1 mA in BRFT mode at a flow rate of 14 mL min-1 showed the best results, yielding 85% bentazon removal, 57% mineralization and SEC values of 0.006 kWh.gTOC-1 after 6 h of treatment. This contribution highlights the use of layered Ti4O7 electrodes as a promising strategy for intensifying EO processes, pointing to a trade-off between the accessibility to the internal electrode structure and the volumetric electrode surface area to enhance the contact between the target molecules and the hydroxyl radicals physisorbed on the electrode surface, while minimizing simultaneously the energy requirements.

In vitro release studies of furosemide reference tablets: influence of agitation rate, USP apparatus, and dissolution media.

Furosemide is a diuretic drug widely used in chronic renal failure. The drug has low solubility and permeability, which cause clinical problems. Studying the in vitro release performance elucidates the rate and extent of drug dissolved from dosage forms under different conditions. Furosemide reference tablets were tested using USP Apparatuses 1 and 2 as well as the flow-through cell method (USP Apparatus 4), a dissolution apparatus that simulates the human gastrointestinal tract better than the other methods. Dissolution profiles were created with USP Apparatuses 1 and 2 at 25, 50, and 75 rpm and 900 mL of 0.1 M hydrochloric acid, acetate buffer (pH 4.5), and phosphate buffer (pH 6.8). USP Apparatus 4 with a laminar flow of 16 mL/min and 22.6 mm cells was used. Drug dissolution was quantified at 274 nm for 60 min. Mean dissolution time, dissolution efficiency, time to 50% dissolution, and time to 80% dissolution data were used to compare dissolution profiles. Additionally, zero-order, first-order, Higuchi, Hixson-Crowell, Makoid-Banakar, and Weibull models were used to adjust furosemide dissolution data. Between USP Apparatus 1 and 2, significant differences were observed in almost all parameters at 50 and 75 rpm (p < 0.05). A similar dissolution profile (f2 > 50) with a pharmacopoeial dissolution method (USP Apparatus 2 at 50 rpm and 900 mL of phosphate buffer pH 5.8) and USP Apparatus 4 (laminar flow of 16 mL/min, 22.6 mm cells, and pH 6.8) was observed. The Weibull function was the best mathematical model to describe the in vitro release performance of furosemide in the three USP dissolution apparatuses. These results could be used to manufacture better furosemide dosage forms and decrease the negative clinical impact of current furosemide formulations.

Effects of season on ecological processes in extensive earthen tilapia ponds in Southeastern Brazil / Efeitos da época sobre os processos ecológicos em viveiros escavados para criação extensiva de tilápias no Sudeste do Brasil

In Southeastern Brazil tilapia culture is conducted in extensive and semi-intensive flow-through earthen ponds, being water availability and flow management different in the rainy and dry seasons. In this region lettuce wastes are a potential cheap input for tilapia culture. This study examined the ecological processes developing during the rainy and dry seasons in three extensive flow-through earthen tilapia ponds fertilized with lettuce wastes. Water quality, plankton and sediment parameters were sampled monthly during a year. Factor analysis was used to identify the ecological processes occurring within the ponds and to construct a conceptual graphic model of the pond ecosystem functioning during the rainy and dry seasons. Processes related to nitrogen cycling presented differences between both seasons while processes related to phosphorus cycling did not. Ecological differences among ponds were due to effects of wind protection by surrounding vegetation, organic loading entering, tilapia density and its grazing pressure on zooplankton. Differences in tilapia growth among ponds were related to stocking density and ecological process affecting tilapia food availability and intraspecific competition. Lettuce wastes addition into the ponds did not produce negative effects, thus this practice may be considered a disposal option and a low-cost input source for tilapia, at least at the amounts applied in this study.(AU)

No sudeste do Brasil, a criação extensiva e semi-intensiva de tilápias é realizada em viveiros escavados com fluxo contínuo, com a disponibilidade e manejo do fluxo de água diferentes nas épocas chuvosa e seca. Na região, os resíduos de alface são um recurso potencialmente de baixo custo para a tilapicultura. Este estudo examinou os processos ecológicos ocorrendo em três viveiros escavados com fluxo contínuo fertilizados com restos de alface para criação extensiva de tilápias durante as épocas chuvosa e seca. Parâmetros de qualidade de água, plâncton e sedimento foram amostrados mensalmente durante um ano. A análise de fator foi utilizada para identificar os processos ecológicos nos viveiros e elaborar um modelo gráfico do funcionamento do ecossistema dos viveiros durante as duas épocas. Os processos relacionados ao ciclo do nitrogênio mostraram diferenças entre as duas épocas, enquanto que os processos relacionados com o ciclo do fósforo não foram influenciados pela época. As diferenças ecológicas entre os viveiros foram principalmente devido aos efeitos do vento, adição de material orgânico e densidade de estocagem. Diferenças no crescimento das tilápias entre os viveiros relacionaram-se com a densidade de estocagem e os processos ecológicos afetando a disponibilidade de alimento e a competição intraespecífica. A adição dos restos de alface nos viveiros não resultou em efeitos negativos, assim esta prática pode ser considerada um destino alternativo e um recurso de baixo custo para a criação extensiva de tilápias, pelo menos nas quantidades investigadas neste estudo.(AU)

Effects of season on ecological processes in extensive earthen tilapia ponds in Southeastern Brazil

Abstract In Southeastern Brazil tilapia culture is conducted in extensive and semi-intensive flow-through earthen ponds, being water availability and flow management different in the rainy and dry seasons. In this region lettuce wastes are a potential cheap input for tilapia culture. This study examined the ecological processes developing during the rainy and dry seasons in three extensive flow-through earthen tilapia ponds fertilized with lettuce wastes. Water quality, plankton and sediment parameters were sampled monthly during a year. Factor analysis was used to identify the ecological processes occurring within the ponds and to construct a conceptual graphic model of the pond ecosystem functioning during the rainy and dry seasons. Processes related to nitrogen cycling presented differences between both seasons while processes related to phosphorus cycling did not. Ecological differences among ponds were due to effects of wind protection by surrounding vegetation, organic loading entering, tilapia density and its grazing pressure on zooplankton. Differences in tilapia growth among ponds were related to stocking density and ecological process affecting tilapia food availability and intraspecific competition. Lettuce wastes addition into the ponds did not produce negative effects, thus this practice may be considered a disposal option and a low-cost input source for tilapia, at least at the amounts applied in this study.

Resumo No sudeste do Brasil, a criação extensiva e semi-intensiva de tilápias é realizada em viveiros escavados com fluxo contínuo, com a disponibilidade e manejo do fluxo de água diferentes nas épocas chuvosa e seca. Na região, os resíduos de alface são um recurso potencialmente de baixo custo para a tilapicultura. Este estudo examinou os processos ecológicos ocorrendo em três viveiros escavados com fluxo contínuo fertilizados com restos de alface para criação extensiva de tilápias durante as épocas chuvosa e seca. Parâmetros de qualidade de água, plâncton e sedimento foram amostrados mensalmente durante um ano. A análise de fator foi utilizada para identificar os processos ecológicos nos viveiros e elaborar um modelo gráfico do funcionamento do ecossistema dos viveiros durante as duas épocas. Os processos relacionados ao ciclo do nitrogênio mostraram diferenças entre as duas épocas, enquanto que os processos relacionados com o ciclo do fósforo não foram influenciados pela época. As diferenças ecológicas entre os viveiros foram principalmente devido aos efeitos do vento, adição de material orgânico e densidade de estocagem. Diferenças no crescimento das tilápias entre os viveiros relacionaram-se com a densidade de estocagem e os processos ecológicos afetando a disponibilidade de alimento e a competição intraespecífica. A adição dos restos de alface nos viveiros não resultou em efeitos negativos, assim esta prática pode ser considerada um destino alternativo e um recurso de baixo custo para a criação extensiva de tilápias, pelo menos nas quantidades investigadas neste estudo.

Effects of season on ecological processes in extensive earthen tilapia ponds in Southeastern Brazil / Efeitos da época sobre os processos ecológicos em viveiros escavados para criação extensiva de tilápias no Sudeste do Brasil

Abstract In Southeastern Brazil tilapia culture is conducted in extensive and semi-intensive flow-through earthen ponds, being water availability and flow management different in the rainy and dry seasons. In this region lettuce wastes are a potential cheap input for tilapia culture. This study examined the ecological processes developing during the rainy and dry seasons in three extensive flow-through earthen tilapia ponds fertilized with lettuce wastes. Water quality, plankton and sediment parameters were sampled monthly during a year. Factor analysis was used to identify the ecological processes occurring within the ponds and to construct a conceptual graphic model of the pond ecosystem functioning during the rainy and dry seasons. Processes related to nitrogen cycling presented differences between both seasons while processes related to phosphorus cycling did not. Ecological differences among ponds were due to effects of wind protection by surrounding vegetation, organic loading entering, tilapia density and its grazing pressure on zooplankton. Differences in tilapia growth among ponds were related to stocking density and ecological process affecting tilapia food availability and intraspecific competition. Lettuce wastes addition into the ponds did not produce negative effects, thus this practice may be considered a disposal option and a low-cost input source for tilapia, at least at the amounts applied in this study.

Resumo No sudeste do Brasil, a criação extensiva e semi-intensiva de tilápias é realizada em viveiros escavados com fluxo contínuo, com a disponibilidade e manejo do fluxo de água diferentes nas épocas chuvosa e seca. Na região, os resíduos de alface são um recurso potencialmente de baixo custo para a tilapicultura. Este estudo examinou os processos ecológicos ocorrendo em três viveiros escavados com fluxo contínuo fertilizados com restos de alface para criação extensiva de tilápias durante as épocas chuvosa e seca. Parâmetros de qualidade de água, plâncton e sedimento foram amostrados mensalmente durante um ano. A análise de fator foi utilizada para identificar os processos ecológicos nos viveiros e elaborar um modelo gráfico do funcionamento do ecossistema dos viveiros durante as duas épocas. Os processos relacionados ao ciclo do nitrogênio mostraram diferenças entre as duas épocas, enquanto que os processos relacionados com o ciclo do fósforo não foram influenciados pela época. As diferenças ecológicas entre os viveiros foram principalmente devido aos efeitos do vento, adição de material orgânico e densidade de estocagem. Diferenças no crescimento das tilápias entre os viveiros relacionaram-se com a densidade de estocagem e os processos ecológicos afetando a disponibilidade de alimento e a competição intraespecífica. A adição dos restos de alface nos viveiros não resultou em efeitos negativos, assim esta prática pode ser considerada um destino alternativo e um recurso de baixo custo para a criação extensiva de tilápias, pelo menos nas quantidades investigadas neste estudo.

Flow-through anastomosis using a T-shaped vascular pedicle for gracilis functioning free muscle transplantation in brachial plexus injury

OBJECTIVE: In gracilis functioning free muscle transplantation, the limited caliber of the dominant vascular pedicle increases the complexity of the anastomosis and the risk of vascular compromise. The purpose of this study was to characterize the results of using a T-shaped vascular pedicle for flow-through anastomosis in gracilis functioning free muscle transplantation for brachial plexus injury. METHODS: The outcomes of patients with brachial plexus injury who received gracilis functioning free muscle transplantation with either conventional end-to-end anastomosis or flow-through anastomosis from 2005 to 2013 were retrospectively compared. In the flow-through group, the pedicle comprised a segment of the profunda femoris and the nutrient artery of the gracilis. The recipient artery was interposed by the T-shaped pedicle. RESULTS: A total of 46 patients received flow-through anastomosis, and 25 patients received conventional end-to-end anastomosis. The surgical time was similar between the groups. The diameter of the arterial anastomosis in the flow-through group was significantly larger than that in the end-to-end group (3.87 mm vs. 2.06 mm, respectively, p<0.001), and there were significantly fewer cases of vascular compromise in the flow-through group (2 [4.35%] vs. 6 [24%], respectively, p=0.019). All flaps in the flow-through group survived, whereas 2 in the end-to-end group failed. Minimal donor-site morbidity was noted in both groups. CONCLUSIONS: Flow-through anastomosis in gracilis functioning free muscle transplantation for brachial plexus injury can decrease the complexity of anastomosis, reduce the risk of flap loss, and allow for more variation in muscle placement. .

Assessing the In Vitro Drug Release from Lipid-Core Nanocapsules: a New Strategy Combining Dialysis Sac and a Continuous-Flow System.

The in vitro assessment of drug release from polymeric nanocapsules suspensions is one of the most studied parameters in the development of drug-loaded nanoparticles. Nevertheless, official methods for the evaluation of drug release from submicrometric carriers are not available. In this work, a new approach to assess the in vitro drug release profile from drug-loaded lipid-core nanocapsules (LNC) was proposed. A continuous-flow system (open system) was designed to evaluate the in vitro drug release profiles from different LNC formulations containing prednisolone or clobetasol propionate (LNC-CP) as drug model (LNC-PD) using a homemade apparatus. The release medium was constantly renewed throughout the experiment. A dialysis bag containing 5 mL of formulation (0.5 mg mL(-1)) was maintained inside the apparatus, under magnetic stirring and controlled temperature (37°C). In parallel, studies based on the conventional dialysis sac technique (closed system) were performed. It was possible to discriminate the in vitro drug release profile of different formulations using the open system. The proposed strategy improved the sink condition, by constantly renewing the release medium, thus maintaining the drug concentration farther from the saturated concentration in the release medium. Moreover, problems due to sampling errors can be easily overcome using this semi-automated system, since the collection is done automatically without interference from the analyst. The system proposed in this paper brings important methodological and analytical advantages, becoming a promising prototype semi-automated apparatus for performing in vitro drug release studies from drug-loaded lipid-core nanocapsules and other related nanoparticle drug delivery systems.

Metabolism and water loss rate of the haematophagous insect Rhodnius prolixus: effect of starvation and temperature.

Haematophagous insects suffer big changes in water needs under different levels of starvation. Rhodnius prolixus is the most important haematophagous vector of Chagas disease in the north of South America and a model organism in insect physiology. Although there have been some studies on patterns of gas exchange and metabolic rates, there is little information regarding water loss in R. prolixus. We investigated whether there is any modulation of water loss and metabolic rate under different requirements for saving water. We measured simultaneously CO2 production, water emission and activity in individual insects in real time by open-flow respirometry at different temperatures (15, 25 and 35°C) and post-feeding days (0, 5, 13 and 29). We found: (1) a clear drop in metabolic rate between 5 and 13 days after feeding that cannot be explained by activity and (2) a decrease in water loss rate with increasing starvation level, by a decrease in cuticular water loss during the first 5 days after feeding and a drop in the respiratory component thereafter. We calculated the surface area of the insects and estimated cuticular permeability. In addition, we analysed the pattern of gas exchange; the change from a cyclic to a continuous pattern was affected by temperature and activity, but it was not affected by the level of starvation. Modulation of metabolic and water loss rates with temperature and starvation could help R. prolixus to be more flexible in tolerating different periods of starvation, which is adaptive in a changing environment with the uncertainty of finding a suitable host.

Comparative in vitro dissolution study of carbamazepine immediate-release products using the USP paddles method and the flow-through cell system.

Dissolution profiles of four carbamazepine immediate-release generic products (200 mg tablets) and the reference product Tegretol® were evaluated using the USP paddles method and an alternative method with the flow-through cell system, USP Apparatus 4. Under official conditions all products met the Q specification, dissolution profiles of generic products were similar to the dissolution profile of the reference product (f 2 > 50) and model-independent parameters showed non significant differences to the reference product except mean dissolution time for product A (p < 0.05). On the other hand, when the flow-through cell system was used, none of the products met the pharmacopeial specification at 15 min and product A did not reach dissolution criteria at 60 min, dissolution profiles of all generic products were not similar to the reference product profile (f 2 < 50) and all model-independent parameters showed significant differences compared to the reference product (p < 0.05). Weibull's model was more useful for adjusting the dissolution data of all products in both USP apparatuses and Td values showed significant differences compared to the reference product (p < 0.05) when USP Apparatus 4 was used. These results indicate that the proposed method, using the flow-through cell system, is more discriminative in evaluating both, rate and extent of carbamazepine dissolution process from immediate-release generic products.