A DOMAIN DECOMPOSITION PRECONDITIONING FOR AN INVERSE VOLUME SCATTERING PROBLEM.

We propose domain decomposition preconditioners for the solution of an integral equation formulation of the acoustic forward and inverse scattering problems. We study both forward and inverse volume problems and propose preconditioning techniques to accelerate the iterative solvers. For the forward scattering problem, we extend the domain decomposition based preconditioning techniques presented for partial differential equations in "A restricted additive Schwarz preconditioner for general sparse linear systems", SIAM Journal on Scientific Computing, 21 (1999), pp. 792-797, to integral equations. We combine this domain decomposition preconditioner with a low-rank correction, which is easy to construct, forming a new preconditioner. For the inverse scattering problem, we use the forward problem preconditioner as a building block for constructing a preconditioner for the Gauss-Newton Hessian. We present numerical results that demonstrate the performance of both preconditioning strategies.

Optimization of River Sampling: Application to Nutrients Distribution in Tagus River Estuary.

The assessment of river water pollution trends is affected by the seasonal variation of river conditions, the variability of pollution sources, the heterogeneity of pollutants distribution, the representativeness/uncertainty of sampling, and the uncertainty of sample analysis. This work presents a methodology to model the uncertainty of river water sampling based on available information about the spatial distribution of the studied parameter in the river. The uncertainty from "single sampling" (SS) or by production of a composite sample by mixing m subsamples collected randomly (RS) or in a line that crosses the sampling circle (LS) was studied. This methodology was applied to the determination of nutrients (NO x, NO2, PO4, and SiO2) in an area of the Tagus River estuary with a range of about 350 m. This methodology can be applied to the determination of the mean value of other parameters in other river areas requiring a previous study of system heterogeneity. The spatial distribution of nutrients in the studied river area was characterized from the analysis of 10 samples collected at known geographical coordinates. The system heterogeneity was described by a three-dimensional ( x, y, z) surface with x and y variables for samples positions and z variable representing the measured nutrient levels. The randomization of this surface for the uncertainty of coordinates and repeatability of nutrient concentration measurement, using Monte Carlo simulations, allowed estimation of the uncertainty of the three sampling strategies: SS, RS, and LS. The uncertainty from RS and LS is equivalent and significantly smaller than that from SS when at least three subsamples are mixed in the composite sample. The sampling relative standard uncertainty ranged from 0.31% to 4.4%, producing nutrient concentration estimates in the river area with a relative expanded uncertainty from 5.9% to 10% with approximately 95% confidence level (coverage factor of 2). The used spreadsheet is available as Supporting Information.

Mass spectrometric studies of the reaction of a blocked arginine with diketonic α-dicarbonyls.

The modification of arginine residues by diketonic α-dicarbonyls, in structural proteins and enzymes studies, is a process known for decades. The chemistry of these reaction processes is, however, not fully understood. Moreover, modification of arginine residues by reaction with α-dicarbonyls in glycation has also not been completely elucidated. Aspects related to the early stages of the condensation of arginine with one dicarbonyl molecule, leading to the formation of dihydroxyimidazolidines and their dehydrated forms, in particular, are here approached in more detail. Taking into consideration the usually rapid kinetics involved in the formation of the early reaction product species, we decided to use fast, sensitive and selective analytical techniques, such as electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS(n)) to monitor the reactions of a blocked arginine (acetyl-arginine) with several selected diketonic α-dicarbonyls, to identify and characterize the mentioned transient species and to probe the reaction mechanism involved. Compounds grouped into two different classes according to their structural similarity were identified, namely acetyl-dihydroxyimidazolidines and acetyl-bis(dihydroxyimidazolidines), together with their dehydrated species. The former compounds are known to exist in solution. The reactivity of acetyl-bis(dihydroxyimidazolidines) seems to be different from that of acetyl-dihydroxyimidazolidines. To note that dehydration appears to be reinforced in acetyl-bis(dihydroxyimidazolidines) chemistry with respect to acetyl-dihydroxyimidazolidine chemistry, while both structurally related compounds involve mostly dihemiaminals reactivity. Two different ion structures are proposed for single dehydrated acetyl-bis(dihydroxyimidazolidines), concerning the two more symmetrical and two more asymmetrical dicarbonyls reacted. In acetyl-bis(dihydroxyimidazolidines) formation, we concluded that the importance of single dehydration relies on the rapid minimization of sterics and energetics of the reaction moieties formed. These reactions occur also in a selective way, regarding the two compound structures proposed for single dehydrated acetyl-bis(dihydroxyimidazolidines). Further considerations are also established for the formation of single dehydrated acetyl-bis(dihydroxyimidazolidines). An explanation for the reversible nature of the reaction of arginine with diketonic dicarbonyls is also provided. This study reinforces the potential of the fast, sensitive and selective electrospray ionization mass spectrometry techniques for the investigation of transient species and their mechanistics, that might otherwise not be feasible by means of the most commonly used spectroscopic techniques.

Revealing microheterogeneities and second order phase transitions in aqueous mixtures of 1-propoxypropan-2-ol at 298 K.

Second order phase transitions corresponding to discontinuities in the plots of Kirkwood-Buff integrals as a function of composition were observed in aqueous mixtures of the amphiphilic molecule, 1-propoxypropan-2-ol, revealing the formation of hydrophobic aggregates and generating microheterogeneities over a limited range of compositions. Electrospray mass spectra, surface tension measurements and solvatochromic parameters confirmed the onsets of different aggregation patterns over the entire composition range, and allowed us to scrutinize the prevailing types of aggregate species. This is seemingly the first time that such discontinuities are clearly assumed as second order phase transitions in a system macroscopically homogeneous and corroborated by other independent tools.

SNPs selection using support vector regression and genetic algorithms in GWAS.

INTRODUCTION: This paper proposes a new methodology to simultaneously select the most relevant SNPs markers for the characterization of any measurable phenotype described by a continuous variable using Support Vector Regression with Pearson Universal kernel as fitness function of a binary genetic algorithm. The proposed methodology is multi-attribute towards considering several markers simultaneously to explain the phenotype and is based jointly on statistical tools, machine learning and computational intelligence. RESULTS: The suggested method has shown potential in the simulated database 1, with additive effects only, and real database. In this simulated database, with a total of 1,000 markers, and 7 with major effect on the phenotype and the other 993 SNPs representing the noise, the method identified 21 markers. Of this total, 5 are relevant SNPs between the 7 but 16 are false positives. In real database, initially with 50,752 SNPs, we have reduced to 3,073 markers, increasing the accuracy of the model. In the simulated database 2, with additive effects and interactions (epistasis), the proposed method matched to the methodology most commonly used in GWAS. CONCLUSIONS: The method suggested in this paper demonstrates the effectiveness in explaining the real phenotype (PTA for milk), because with the application of the wrapper based on genetic algorithm and Support Vector Regression with Pearson Universal, many redundant markers were eliminated, increasing the prediction and accuracy of the model on the real database without quality control filters. The PUK demonstrated that it can replicate the performance of linear and RBF kernels.

Method to link medicines to diseases using multiplex networks.

The reuse of well-established medicines using computational modeling has gained a lot of attention due to its tremendous benefits. Based on this perspective, a new method for linking known medicines to diseases is proposed. The creation of a new treatment or medicine can be financially and temporally costly and the reuse of medicines is one possibility to accelerate this process efficiently. The main purpose of the reuse of medicines is to reduce some stages of the development of new medicines, motivating the proposition of several methods nowadays. In this work, a new method is developed aiming to connect known medicines to diseases based on available networks of protein interactions and available lists of medicines that affect protein action. The concepts of multiplex networks are used to connect subgraphs of vertices that represent medicines and proteins. The core of the procedure is determined by a weighting strategy constructed to define precisely the more relevant connections. The method was compared to other network link methods in the literature and a case study was presented and evaluated by the proposed method.

Exploring the Benefits of Nutritional and Chemical Characteristics of Touriga Nacional and Arinto Varieties (Vitis vinifera L.).

Environmental degradation leads to an unsustainable food system. In addition to this issue, the consumption of foods that improve people's health and well-being is recommended. One of the alternatives is undoubtedly the use of by-products of winemaking, namely in the form of grape pomace flour (GPF). To verify the benefits of using the Touriga Nacional and Arinto (Vitis vinifera L.) flour varieties, analytical determinations were made to identify and quantify different components. In terms of nutritional characterization, the Touriga Nacional GPF showed results that indicate better nutritional quality than the Arinto GPF. The Touriga Nacional and Arinto samples had protein contents of 10.13% and 8.38%, polyunsaturated fatty acids of 6.66% and 5.18%, soluble dietary fiber of 14.3% and 1.7%, and insoluble dietary fiber of 55.1% and 46.4%, respectively. The anthocyanins, proanthocyanidins, and flavonols presented in samples were detected by HPLC-DAD/ESI-MS. Atomic absorption spectrometry revealed elevated concentrations of certain elements in Touriga Nacional compared to Arinto, with the former showing higher levels of aluminum (130 mg/kg) and iron (146 mg/kg) against the latter's Al (120 mg/kg) and Fe (112 mg/kg) content. GPF could become a valuable ingredient due to its nutritional quality and high content of various polyphenols.

Long-term surface hardness and monomer conversion of a nanoflled and a microhybrid composite resin.

OBJECTIVE: This study aims to evaluate the degree of conversion (DC) and hydrolytic degradation through the Vickers hardness test (HV) of a nanoflled (Filtek(TM) Z-250, 3M) and a microhybrid (Filtek(TM)Supreme-XT, 3M) composite resin. MATERIALS AND METHODS: Eight disk-shaped specimens (4 mm diameter × 2 mm thick, ISO 4049) of each material were prepared for each test. Composites were inserted into single increment in a metallic matrix and light-cured for 40 seconds. VH readings were performed for each specimen at predetermined intervals: immediately after polymerization (control), 1, 2, 3, 7, 14, 21, 30 and 180 days. After curing, initial hardness measurements were performed and the specimens were immersed in artifcial saliva at 37°C. For DC (%), specimens were ground, pressed with KBr and analyzed by FT-IR spectrophotometer. RESULTS: Student t-test showed that there was no difference between the resins for DC (p = 0.252). ANOVA analysis revealed that Z-250 VH means were all greater than S-XT, for both top and bottom surfaces, whatever the storage-period in artifcial saliva (p < 0.001). After 180 days of storage, the hardness obtained for S-XT was similar with that at the baseline, for both top and bottom surfaces. While for Z-250 hardness was not signifcantly different from baseline only for top surface, but there was a signifcant decrease observed in hardness for bottom surface. CONCLUSION: The materials tested showed no evidence of hydrolytic degradation in a signifcant way, in a 6-month storage-time in artifcial saliva. Nanoflled resin presents a monomer conversion comparable to the conventional microhybrid.

Evaluation of temporal trends and correlations of physical-chemical parameters in vast oceanic areas robust to information uncertainty.

The physical-chemical monitoring of vast oceanic areas aims at assessing the status and evolution of the environmental resource for its exploration, protection and/or better understanding. However, the interpretation of monitoring data is affected by ocean seasonality and heterogeneity, and by the quality of sampling and characterization tools used to study the environment. All these factors contribute to the uncertainty of collected information that should be expressed in determined parameter values or trends. A trend of a studied parameter quantified by values difference is significant if the observed absolute value of the difference is larger than their expanded uncertainty. The correlation of studied parameters, useful for their interpretation, is equality affected by the mentioned sources of uncertainty. This work describes the metrologically sound evaluation of trends and correlations of physicochemical parameters of vast oceanic areas where all uncertainty sources affecting the information are considered by simulating their complex impact by the Monte Carlo Method. The described methodology was successfully used to study the impact of summer upwelling in an 800 km2 coastal area offshore two large cities in Portugal. Nutrients, conductivity, salinity and temperature trends and correlations are distinguished from system heterogeneity, sampling and sample analysis uncertainty for a 99% confidence level.

Increased oyster aquaculture in the Sado Estuary (Portugal): How to ensure ecosystem sustainability?

Aquaculture is one of the fastest growing sectors in the world. However, this may come with a cost, as increasing aquatic production is likely to impose changes in the environment. To ensure ecosystem sustainability, it is essential to think on this larger scale. This study aims to use the Delft3D model suite to evaluate the ecological carrying capacity for bivalve production in the Sado Estuary (Portugal), under present and future conditions (2050). Scenarios for increased oyster production resulted in reductions of chlorophyll a associated with increased nutrient concentrations. In the most extreme production scenario, which considered an increase of 100 ha in production area, a predicted decrease of 90 % in phytoplankton biomass was observed. Climate change (CC) was incorporated as an increase in sea level and water temperature, as well as a reduction in river flow. Under present oyster production conditions, CC revealed contrasting patterns, i.e. an increase in chlorophyll a concentrations and a reduction in nutrients. These results suggest that CC has a positive effect in counteracting the impacts of increased oyster production, however further research is necessary. All scenarios point to reduced dissolved oxygen concentrations, highlighting the need to monitor this parameter. Given the difficulty in defining what are unacceptable impacts to the ecosystem it would be prudent to include a socio-ecological framework in the future, in order to integrate ecosystem services and the perception of local stakeholders.

Development of a Multispecies Double-Antigen Sandwich ELISA Using N and RBD Proteins to Detect Antibodies against SARS-CoV-2.

SARS-CoV-2 infects humans and a broad spectrum of animal species, such as pets, zoo animals, and nondomestic animals. Monitoring infection in animals is important in terms of the risk of interspecies transmission and the emergence of new viral variants. Economical, fast, efficient, and sensitive diagnostic tests are needed to analyze animal infection. Double-antigen sandwich ELISA has the advantage of being multispecies and can be used for detecting infections caused by pathogens that infect several animal hosts. This study aimed to develop a double-antigen sandwich ELISA using two SARS-CoV-2 proteins, N and RBD. We compared its performance, when using these proteins separately, with an indirect ELISA and with a surrogate virus neutralization test. Positive and negative controls from a cat population (n = 31) were evaluated to compare all of the tests. After confirming that double-antigen sandwich ELISA with both RBD and N proteins had the best performance (AUC= 88%), the cutoff was adjusted using positive and negative samples from cats, humans (n = 32) and guinea pigs (n = 3). The use of samples from tigers (n = 2) and rats (n = 51) showed good agreement with the results previously obtained using the microneutralization test. Additionally, a cohort of samples from dogs with unknown infection status was evaluated. These results show that using two SARS-CoV-2 proteins in the double-antigen sandwich ELISA increases its performance and turns it into a valuable assay with which to monitor previous infection caused by SARS-CoV-2 in different animal species.

Reactions of aminoguanidine with α-dicarbonyl compounds studied by electrospray ionization mass spectrometry.

Aminoguanidine possesses extensive pharmacological properties. This drug is recognized as a powerful α-dicarbonyl scavenger. In order to better elucidate the reactivity of aminoguanidine with α-dicarbonyls, aminoguanidine was reacted with several aldehydic and diketonic α-dicarbonyls. Electrospray ionization mass spectrometry is a suitable technique to study chemical and biochemical processes, and was selected for the purpose. In aminoguanidine reactions, triazines were detected and, other compounds that have never been reported before were identified. Triazine precursor forms were detected, namely tetrahydrotriazines and singly dehydrated tetrahydrotriazines. Moreover, species with bicyclic ring structures, and dehydrated forms, were also identified in aminoguanidine reactions. These species appear to result from tetrahydrotriazines and triazines reactions with one dicarbonyl molecule. Experiments revealed that these bicyclic species, in particular the ones resulting from triazines reactivity, could exist in solution, since they were both identified in the reactions of aminoguanidine and of a selected triazine with the dicarbonyls studied. The results obtained, regarding aminoguanidine/triazines reactivities, appear to support the capability of triazines to condensate and form polycyclic ring structures, and also to support literature mechanistic data for dihydroimidazotriazines formation via dihydroxyimidazolidine-triazines. The data obtained in this study may prove to be valuable to complement solution information, concerning the reactivity of amines with α-dicarbonyls, in particular.

Impacts of postpartum length at the initiation of the fixed-time artificial insemination protocol on pregnancy rates of Bos indicus beef cows.

The shortest interval between calving and initiation of fixed-time artificial insemination (FTAI) protocols recommended in Brazilian cow-calf systems is 30 d, based on research that characterized uterine involution and incidence of uterine disorders in Bos taurus females. Prevalence of uterine disorders such as subclinical endometritis is limited in Nelore (B. indicus) cows as early as 28 d after calving. We hypothesized that Nelore cows can receive an FTAI protocol as early as 20 d postpartum (DPP) and still experience satisfactory reproductive results. This study evaluated pregnancy rates in 5,258 Nelore cows (n = 1,703 primiparous and 3,555 multiparous) according to DPP at the initiation of the FTAI protocol. Cow body condition score (BCS) was recorded at FTAI, and pregnancy diagnosis was performed ~30 d after FTAI. Cows were ranked within parity by DPP at the initiation of the FTAI protocol and classified according to 5-d intervals (e.g., ≤15 DPP, 16 to 20 DPP, 21 to 26 DPP, until cows with ≥76 DPP). Data were analyzed within parity, using cow as experimental unit and orthogonal polynomial contrasts (linear, quadratic, or cubic) generated using the mean DPP of each DPP class. In both parities, cow BCS at FTAI decreased linearly (P ≤ 0.01) with the advance of DPP (e.g., 4.79, 4.00, and 3.73 in primiparous, and 4.95, 3.70, and 3.23 in multiparous cows classified as ≤15 DPP, 36 to 40 DPP, ≥76 DPP, respectively). The pregnancy rate to FTAI was affected quadratically (P < 0.01) by DPP for both parities. In primiparous cows, the pregnancy rate increased until 36 to 40 DPP (60%), remained near this level until 51 to 60 DPP, and then decreased with the advance of DPP, whereas cows classified as 21 to 25 DPP expressed satisfactory results (41.5%). In multiparous cows, the pregnancy rate increased until 46 to 50 DPP (70.8%), remained near this level until 56 to 60 DPP, and then decreased with the advance of DPP, whereas cows classified as 21 to 25 DPP also expressed satisfactory results (63.6%). Collectively, primiparous and multiparous Nelore cows evaluated herein experienced optimal pregnancy rates when the FTAI protocol was initiated within 30 to 60 DPP, although reasonable outcomes were observed when the FTAI protocol was initiated as early as 21 DPP. Hence, the interval between calving and initiation of the FTAI protocol can be shortened by 10 d in Nelore females and still yield acceptable pregnancy rates, which can be of great value to cows that calve immediately prior to or during the annual breeding season.

Evaluation of seawater composition in a vast area from the Monte Carlo simulation of georeferenced information in a Bayesian framework.

The detection of composition or pollution trends of vast environmental water areas, from a river, lake or sea, requires the determination of the mean concentration of the studied component in the studied area at defined depth in, at least, two occasions. Mean concentration estimates of a large area are robust to system heterogeneity and, if expressed with uncertainty, allow assessing if observed trends are meaningful or can be attributed to the measurement process. Mean concentration values and respective uncertainty are more accurately determined if various samples are collected from the studied area and if samples coordinates are considered. The spatial representation of concentration variation and the subsequent randomization of this model, given coordinates and samples analysis uncertainty, allows an improved characterization of studied area and the optimization of the sampling process. Recently, this evaluation methodology was described and implemented in a user-friendly MS-Excel file. This tool was upgraded to allow determinations close to zero concentration and "bottom-up" uncertainty evaluations of collected samples analysis. Since concentrations cannot be negative, this prior knowledge is merged with the original measurements in a Bayesian uncertainty evaluation that improves studied area description and sampling modelling. The Bayesian assessment avoids the underestimation of concentrations distribution by assuming that negative concentrations are impossible. This tool was successfully applied to the determination of reactive phosphate concentration in a vast ocean area of the Portuguese coast. The new version of the developed tool is made available as Supplementary Material.

Tidal variability of water quality parameters in a mesotidal estuary (Sado Estuary, Portugal).

To establish effective water quality monitoring strategies in estuaries, it is imperative to identify and understand the main drivers for the variation of water quality parameters. The tidal effect is an important factor of the daily and fortnightly variability in several estuaries. However, the extent of that influence on the different physicochemical and biological parameters is still overlooked in some estuarine systems, such as the Sado Estuary, a mesotidal estuary located on the west coast of Portugal. The main objective of this study was to determine how the water quality parameters of the Sado Estuary varied with the fortnightly and the semidiurnal tidal variation. To achieve this goal, sampling campaigns were conducted in May/18, Nov/18 and Jun/19, under neap and spring tidal conditions, with data collection over the tidal cycle. Results were observed to be significantly influenced by the tidal variation, in a large area of the estuary. Flood seemed to mitigate possible effects of nutrient enrichment in the water column. Additionally, significant differences were also observed when considering the different sampling stations. Temperature, Suspended Particulate Matter (SPM) and nutrients showed the highest values at low water. Lastly, the implications of the tidal variability in the evaluation of the water quality according to Water Framework Directive were also discussed, highlighting the importance of studying short-time scale variations and the worst-case scenario to ensure water quality is maintained. These findings are relevant for the implementation of regional management plans and to promote sustainable development.

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometric and semi-empirical calculations study of five isoflavone aglycones.

Five isoflavones, daidzein, genistein, formononetin, prunetin and biochanin A, known for their biological properties, are investigated by electrospray ionization mass spectrometry in the positive ion mode. The most probable protonation sites are determined taking into account semi-empirical calculations using the PM6 Hamiltonian. Fragmentation mechanisms are proposed based on accurate mass measurements, MS(3) experiments and supported by the semi-empirical calculations. Some of the fragmentation pathways were found to be dependent on the substitution pattern of the B-ring and the ions afforded by these fragmentations can be considered as diagnostic. It was possible to distinguish between prunetin and biochanin A, two isobaric isoflavone aglycones included in this study. Furthermore, a comparison of the fragmentation patterns of genistein and biochanin A, two isoflavones, with those of their flavone counterparts, apigenin and acacetin, enabled us to identify some key ions mainly due to structural features, allowing distinction to be made between these two classes of compounds.

Behaviour of 4-(-2-hydroxyethyl)-1-piperazineethanesulfonic acid under electrospray ionization mass spectrometry conditions.

Our previous experiments on ESI-MS analysis of reaction mixture solutions containing HEPES (4-(-2- hydroxyethyl)-1-piperazineethanesulfonic acid), a commonly used buffer, indicated that HEPES species did not significantly suppress analyte species, even in reaction mixture solutions with significant amounts of HEPES. With the purpose of investigating the behaviour of HEPES under ESI-MS conditions, HEPES aqueous solutions and HEPES aqueous solutions containing analyte with high and low polarity and with different acid/base chemistry, were therefore investigated. For electrosprayed aqueous solutions of HEPES with concentrations above 10(-5) M, an enhanced formation of HEPES multimer ions, regarding HEPES monomer ions formation, was observed. This enhanced formation of HEPES multimer ions is much higher than the one observed for other polar compounds, such as acetyl-arginine, acetyl-lysine and histidine. Information from solution behaviour such as, HEPES concentration, solution pH, and instrumental factors, namely the capillary temperature, was related with information from mass spectra. The results obtained led us to conclude that the formation of HEPES ions is related with the initial solution composition. The influence of analyte species on HEPES species formation, for electrosprayed HEPES solutions with analyte, was also investigated. The variations observed for HEPES monomer and multimer ions abundances, which were found to be consistent with those observed for analyte monomer ions abundances, were related with type of analyte, i.e. to their acid/base nature. Strikingly, the variations observed between HEPES monomer and multimer ions abundances, enable to discriminate among the different influence of analyte species on HEPES species formation. The results obtained also enabled to provide an explanation for the observation that HEPES species do not suppress significantly analyte species ion signals, when high concentrated HEPES solutions with analyte are electrosprayed. According to our results, the association behaviour between HEPES species seems to be preserved in the gas phase during electrospray ionization. This observation may provide some information that may be useful regarding the behaviours involved in the gas phase ion formation process from charged droplets during electrospray ionization or, at least, to differentiate among behaviours.

Antihyperglycaemic and protective effects of flavonoids on streptozotocin-induced diabetic rats.

The antihyperglycaemic effect of eight standard flavonoids, previously identified in the ethanol extract of the claimed antidiabetic plant Genista tenera, was evaluated on streptozotocin (STZ)-induced diabetic Wistar rats. The aglycones apigenin, chrysoeriol and genistein, the monoglucosides apigenin 7-O-glucoside, luteolin 7-O-glucoside and genistein 7-O-glucoside and the diglycosides rutin and luteolin 7,3'-di-O-glucoside were administered i.p. for 7 days (4 mg/kg b.w./day). The protective effect of these compounds over liver and kidneys of STZ-diabetic models was also evaluated by the determination of seric AST, ALT and urea levels. After 7 days of treatment, apigenin, chrysoeriol and genistein significantly lowered the blood glucose levels of diabetic animals; this effect was more pronounced (P < 0.01) in the oral glucose tolerance test. Glucose tolerance was also significantly improved in the rutin (P < 0.01) and in the genistein 7-O-glucoside (P < 0.05) treated groups. In addition, almost all the tested compounds effectively protected the liver and kidneys against STZ-induced damage in rats.

Determination of river water composition trends with uncertainty: Seasonal variation of nutrients concentration in Tagus river estuary in the dry 2017 year.

The assessment of long-term trends in river water composition is hampered by river composition heterogeneity, and sampling and sample analysis uncertainty. This work describes a novel methodology for the reliable detection of small river composition trends by taking all relevant uncertainty components into account. The methodology was applied to study the variation of nutrients concentration of Tagus river estuary in the extremely dry 2017 year. Mean nutrient concentrations were determined with an uncertainty that combines sampling and sample analysis uncertainty by the Monte Carlo Method. The nutrient concentration variation observed in two occasions is meaningful if the difference of mean concentrations is metrologically different from zero for a 95% confidence level. The observed meaningful NO2 increase, and SiO2 and NOx variations is justified by dissolved oxygen reduction, decreased freshwater input and algal productivity variations. The developed tool can be applied to the assessment of other composition trends in rivers.

The opposing effects of the flavonoids isoquercitrin and sissotrin, isolated from Pterospartum tridentatum, on oral glucose tolerance in rats.

The effect of an aqueous extract of Pterospartum tridentatum on the blood glucose levels of normal Wistar rats was investigated in a situation of oral glucose challenge. The extract at 300 mg/kg showed an antihyperglycaemic effect in the first 30 min after glucose challenge but then the blood glucose levels rose above those of the control group, indicating the presence of compounds with different effects on glucose tolerance. Nine compounds of isoflavone and flavonol skeletons were identified in the extract by HPLC-ESI-MS(n), four of them being identified for the first time in this species. The isoflavone sissotrin and the flavonol derivative, isoquercitrin, were selected for the oral glucose tolerance test. Isoquercitrin (100 mg/kg) showed time-dependent antihyperglycaemic activity by delaying the post-oral glucose load glycaemic peak at 30 min, as did the sodium-dependent glucose transporter inhibitor phloridzin (100 mg/kg). In contrast, sissotrin (100 mg/kg) showed an opposite effect, impairing glucose tolerance. In conclusion, these preliminary results indicate that the effect of the extract on blood glucose may be either antihyperglycaemic or hyperglycaemic. Additionally, as far as is known, these are the first in vivo results on the acute antihyperglycaemic potential of isoquercitrin.