Impact of 10 Dietary Sterols on Growth and Reproduction of Daphnia galeata

In crustaceans, cholesterol is anEssential nutrient, which they must directly obtain from their food or by bioconversion from other dietary sterols. Eukaryotic phytoplankton contain a great variety of sterols that differ from cholesterol in having additional substituents or different positions and/or number of double bonds in the side chain or in the sterol nucleus. In this study, we investigated to what extent these structural features affect the growth and reproduction of Daphnia galeata in standardized growth experiments with the cyanobacterium Synechococcus elongatus supplemented with single sterols as food source. The results indicated that ⁵ (sitosterol, stigmasterol,Desmosterol) and ^5,7 (7-dehydrocholesterol, ergosterol) sterols meet the nutritional requirements of the daphnids, while the ⁷ sterol lathosterol supports somatic growth and reproduction to a significantly lower extent than cholesterol. Dihydrocholesterol (⁰) and lanosterol (⁸) did not improve the growth of D. galeata, and growth was adversely affected by the ⁴ sterol allocholesterol. Sterols seem to differ in their allocation to somatic growth and reproduction. Thus, structural differences of dietary sterols have pronounced effects on life-history traits of D. galeata.     

Retroconversion of Docosapentaenoic Acid (n-6): an Alternative Pathway for Biosynthesis of Arachidonic Acid in Daphnia magna

The aim of this study was to assess metabolic pathways for arachidonic acid (20:4n-6) biosynthesis in Daphnia magna. Neonates of D. magna were maintained on [¹³C] enriched Scenedesmus obliquus and supplemented with liposomes that contained separate treatments of unlabeled docosapentaenoic acid (22:5n-6), 20:4n-6, linoleic acid (18:2n-6) or oleic acid (18:1n-9). Daphnia in the control treatment, without any supplementary fatty acids (FA) containing only trace amounts of 20:4n-6 (~0.3 % of all FA). As expected, the highest proportion of 20:4n-6 (~6.3 %) was detected in Daphnia that received liposomes supplemented with this FA. Higher availability of 18:2n-6 in the diet increased the proportion of 18:2n-6 in Daphnia, but the proportion of 20:4n-6 was not affected. Daphnia supplemented with 22:5n-6 contained ~3.5 % 20:4n-6 in the lipids and FA specific stable isotope analyses validated that the increase in the proportion of 20:4n-6 was due to retroconversion of unlabeled 22:5n-6. These results suggest that chain shortening of 22:5n-6 is a more efficient pathway to synthesize 20:4n-6 in D. magna than elongation and desaturation of 18:2n-6. These results may at least partially explain the discrepancies noticed between phytoplankton FA composition and the expected FA composition in freshwater cladocerans. Finally, retroconversion of dietary 22:5n-6 to 20:4n-6 indicates Daphnia efficiently retain long chain n-6 FA in lake food webs, which might be important for the nutritional ecology of fish.     

The Use of Spectrofluorimetry for Monitoring the Bioaccumulation and the Biotransformation of Polycyclic Aromatic Hydrocarbons in Daphnia magna

A rapid and direct spectrofluorimetric method was tested in order to monitor the bioaccumulation of PAHs in Daphnia magna in a control media. After exposure to water containing benzo[ a ]pyrene or fluoranthene, daphnids were put in solvent, sonicated, and filtered. The fluorescence spectrum observed in the filtrate was recorded. Results were compared to HPLC measurements of the same pools of organisms. In fluoranthene experiments, the fluorescence peak of the daphnid extract spectrum was linearly related to the PAH content as measured with HPLC. In benzo[ a ]pyrene experiments, other fluorescent compounds progressively appeared in the sample. They were assumed to be metabolites. A linear regression involving fluorescence intensities at two different wavelengths was necessary for a satisfactory correlation with HPLC measurements. A water extraction was performed to isolate metabolites. None or very few fluoranthene metabolites were isolated in the aqueous phase, whereas increasing benzo[ a ]pyrene metabolites were observed while the exposure time increased.     

Using Theoretical Correction Factors for Quantitative Analysis of Sterols and Sterol Concentrates

A common detector for the analysis of sterols and sterol concentrates by gas chromatography is the flame ionization detector (FID). The detector measures the response of ions from a molecule as it is pyrolyzed in a hydrogen flame. The response is relative to the number of hydrogen and carbon atoms in a molecule and it gives different responses for the same amounts of different analytes. Theoretical correction factors (TCF) can be used to account for these differences during data analysis and are based upon the number of active carbons in a molecule and can be calculated from known structures. TCF have been used to provide a more reproducible approach to the analysis of sterol concentrates in raw materials. Use of empirical correction factors (ECF) requires determination of relative responses for each analyte and also a high purity standard (and determination of that purity), which can be expensive or difficult to obtain for the more uncommon sterols. Experiments have been conducted to determine ECF for Ergost-5-en-3-ol, (3β,24R), commonly known as campesterol, Stigmasta-5,22-dien-3-ol, (3β,22E), commonly known as stigmasterol, and Stigmast-5-en-3-ol, (3β), commonly known as β-sitosterol and compared to the calculated TCF for these same sterols. The experiments evaluated differences in concentration, standard purity, and injection technique and found that all three factors had an effect on the determination of ECF. It was also found that cool on column injections gave more accurate ECF values and are preferable for quantitative analysis of sterols.     

A Comparative Approach for the Preparation and Physicochemical Characterization of Lecithin Liposomes Using Chloroform and Non‐Halogenated Solvents

Organic solvents used in various pharmaceutical preparations may be associated with chronic health effects, with special emphasis on halogenated solvents. Liposomes, lipid bilayer membrane carriers, have potential applications in targeted drug delivery systems. The non‐halogenated solvents, acetonitrile and ethanol, were used in comparison to commonly used chloroform. The effect of solvents and dispersion medium was demonstrated using physicochemical properties, stability studies and hemolytic activity. Increased sonication time showed decreased particle size in phosphate buffer saline and water medium. Vesicles prepared from all solvents exhibited better stability in phosphate saline buffer than water when evaluated by particle size and zeta potentials. Liposomes showed a positive zeta potential in buffer solution whereas liposomes in water showed negative zeta potential. In vitro hemolytic activity of liposomes was done with fresh human red blood cells. Results in buffer solution were in the range of 1–4 % which further proved this medium superior to pure water. The findings of this study are helpful in suggesting the formulation of thin films by less hazardous solvents in terms of the environmental integrity and human health.     

A Statistical Approach for Biogenic Synthesis of Nano-Silica from Different Agro-Wastes

Silicon - Biogenic silica is an excellent alternative to synthetic silica because of its capricious configuration, density, composition, less toxicity, environmentally friendly synthesis and...     

Cloud Point Extraction of Orange II and Orange G Using Neutral and Mixed Micelles: Comparative Approach Using Experimental Design

The aim of this work was to compare two synthetic dyes, Orange G (7-Hydroxy-8-(phenylazo)-1,3-naphthalenedisulfonic acid, disodium salt) and Orange II (p-(2-Hydroxy-1-naphthylazo) benzenesulfonic acid, sodium salt), towards cloud point extraction from colored water. Three commercial non-ionic surfactants were used in this work: Oxo-C₁₅E₇, Oxo-C₁₀E₃, and Triton X-100. The experimental extraction results were expressed by the following three responses: percentage of the extracted dye (E), residual concentrations of dye in the dilute phase (X_s,w), and the volume fraction of coacervate (?_C) at the equilibrium. The results obtained for each parameter were represented on three dimensional diagrams using an empirical smoothing method. In optimal conditions Orange II concentration in the effluent was reduced to about 227 times, whereas E did not exceed 55% using Oxo-C₁₅E₇ in the case of Orange G extraction. However, when a small amount (0.025 wt.%) of cetyltrimethylammonium bromide (CTAB) was combined with Oxo-C₁₀E₃ as a mixed micelles system, the results showed that the extraction percentage of Orange G increased from 55 to 98%. Indeed, the concentration of this dye in the effluent was reduced to about 400 times. Finally, the extraction extent of both dyes was found to be low at basic pH, which may be useful for surfactant regeneration.     

UMPred-FRL: A New Approach for Accurate Prediction of Umami Peptides Using Feature Representation Learning

Umami ingredients have been identified as important factors in food seasoning and production. Traditional experimental methods for characterizing peptides exhibiting umami sensory properties (umami peptides) are time-consuming, laborious, and costly. As a result, it is preferable to develop computational tools for the large-scale identification of available sequences in order to identify novel peptides with umami sensory properties. Although a computational tool has been developed for this purpose, its predictive performance is still insufficient. In this study, we use a feature representation learning approach to create a novel machine-learning meta-predictor called UMPred-FRL for improved umami peptide identification. We combined six well-known machine learning algorithms (extremely randomized trees, k-nearest neighbor, logistic regression, partial least squares, random forest, and support vector machine) with seven different feature encodings (amino acid composition, amphiphilic pseudo-amino acid composition, dipeptide composition, composition-transition-distribution, and pseudo-amino acid composition) to develop the final meta-predictor. Extensive experimental results demonstrated that UMPred-FRL was effective and achieved more accurate performance on the benchmark dataset compared to its baseline models, and consistently outperformed the existing method on the independent test dataset. Finally, to aid in the high-throughput identification of umami peptides, the UMPred-FRL web server was established and made freely available online. It is expected that UMPred-FRL will be a powerful tool for the cost-effective large-scale screening of candidate peptides with potential umami sensory properties.     

Sterols in chloroplasts: A description of two qualitatively distinct forms

Chloroplasts from eight plant species have been extracted sequentially with petroleum ether (PE) and acetone (A) and the extracts analyzed for sterols. Cholesterol was a component of all fractions analyzed but it was found that the A fraction of each species contained relatively much more cholesterol than the PE fraction. Other components of the PE sterol fractions were plant sterols typical of the species examined and were quantitatively markedly different from those in the corresponding A fractions. The yield of sterol from chloroplasts was found to be 0.02–0.03% and the ratio of the PE/A fractions to be 5∶1–19∶1.     

Commercial Bee Pollen with Different Geographical Origins: A Comprehensive Approach

Since the primordial of humanity, pollen has been considered a good source of nutrients and energy. Its promising healing properties have also been referred to. The present study aimed to characterize, for the first time, eight commercial pollens from Portugal and Spain available on the market studying the legislation on labeling, pollinic origin, physicochemical and microbiological analyses and identification of yeasts. Eleven botanical families were found amongst the samples. The most abundant family and the most dominant pollen was Cistaceae. The moisture content, ash, a_w, pH, reducing sugars, carbohydrates, proteins, lipids and energy were analyzed and the specific parameters were within the specifications required by some countries with legislation regarding these parameters. Microbiologically commercial pollen showed acceptable safety for the commercial quality and hygiene. All samples showed negative results for toxigenic species. The microorganisms studied were aerobic mesophiles, yeasts and moulds, coliforms, Escherichia coli, Staphylococcus aureus, Salmonella and sulfite-reducing Clostridium. During the work, six yeasts species were isolated from pollen, with Rhodotorula mucilaginosa being the most abundant, as it was present in four samples.     

Integration of Design and Control: A Robust Control Approach Using MPC

This paper presents a new method to integrate process control with process design. The process design is based on steady‐state costs, .i.e., capital and operating costs. Control is incorporated into the design in terms of a variability cost. This term is calculated based on the non‐linear process model, represented here as a nominal linear model supplemented with model parameter uncertainty. Robust control tools are then used within the approach to assess closed‐loop robust stability and to calculate closed‐loop variability. The integrated method results in a non‐linear constrained optimization problem with an objective function that consists of the sum of the steady costs and the variability cost. Optimization using the traditional sequential approach and the new integrated method was applied to design a multi‐component distillation column using a Model Predictive Control (MPC) algorithm. The optimization results show that the integrated method can lead to significant cost savings when compared to the traditional sequential approach. In addition, an RGA analysis was performed to study the effects of process interactions on the optimization results.     

Identification of Myocardial Insulin Resistance by Using Liver Tests: A Simple Approach for Clinical Practice

Background: We report that myocardial insulin resistance (mIR) occurs in around 60% of patients with type 2 diabetes (T2D) and was associated with higher cardiovascular risk in comparison with patients with insulin-sensitive myocardium (mIS). These two phenotypes (mIR vs. mIS) can only be assessed using time-consuming and expensive methods. The aim of the present study is to search a simple and reliable surrogate to identify both phenotypes. Methods: Forty-seven patients with T2D underwent myocardial [18F]FDG PET/CT at baseline and after a hyperinsulinemic–euglycemic clamp (HEC) to determine mIR were prospectively recruited. Biochemical assessments were performed before and after the HEC. Baseline hepatic steatosis index and index of hepatic fibrosis (FIB-4) were calculated. Furthermore, liver stiffness measurement was performed using transient elastography. Results: The best model to predict the presence of mIR was the combination of transaminases, protein levels, FIB-4 score and HOMA (AUC = 0.95; sensibility: 0.81; specificity: 0.95). We observed significantly higher levels of fibrosis in patients with mIR than in those with mIS (p = 0.034). In addition, we found that patients with mIR presented a reduced glucose uptake by the liver in comparison with patients with mIS. Conclusions: The combination of HOMA, protein, transaminases and FIB-4 is a simple and reliable tool for identifying mIR in patients with T2D. This information will be useful to improve the stratification of cardiovascular risk in T2D.     

Maternal Responses and Adaptive Changes to Environmental Stress via Chronic Nanomaterial Exposure: Differences in Inter and Transgenerational Interclonal Broods of Daphnia magna

There is increasing recognition that environmental nano-biological interactions in model species, and the resulting effects on progeny, are of paramount importance for nanomaterial (NM) risk assessment. In this work, Daphnia magna F0 mothers were exposed to a range of silver and titanium dioxide NMs. The key biological life history traits (survival, growth and reproduction) of the F1 intergenerations, at the first (F1B1), third (F1B3) and fifth (F1B5) broods, were investigated. Furthermore, the F1 germlines of each of the three broods were investigated over 3 more generations (up to 25 days each) in continuous or removed-from NM exposure, to identify how the length of maternal exposure affects the resulting clonal broods. Our results show how daphnids respond to NM-induced stress, and how the maternal effects show trade-offs between growth, reproduction and survivorship. The F1B1 (and following germline) had the shortest F0 maternal exposure times to the NMs, and thus were the most sensitive showing reduced size and reproductive output. The F1B3 generation had a sub-chronic maternal exposure, whereas the F1B5 generation suffered chronic maternal exposure where (in most cases) the most compensatory adaptive effects were displayed in response to the prolonged NM exposure, including enhanced neonate output and reduced gene expression. Transgenerational responses of multiple germlines showed a direct link with maternal exposure time to ‘sub-lethal’ effect concentrations of NMs (identified from standard OECDs acute toxicity tests which chronically presented as lethal) including increased survival and production of males in the F1B3 and G1B5 germlines. This information may help to fine-tune environmental risk assessments of NMs and prediction of their impacts on environmental ecology.     

Identification of Potential Insect Growth Inhibitor against Aedes aegypti: A Bioinformatics Approach

Aedes aegypti is the main vector that transmits viral diseases such as dengue, hemorrhagic dengue, urban yellow fever, zika, and chikungunya. Worldwide, many cases of dengue have been reported in recent years, showing significant growth. The best way to manage diseases transmitted by Aedes aegypti is to control the vector with insecticides, which have already been shown to be toxic to humans; moreover, insects have developed resistance. Thus, the development of new insecticides is considered an emergency. One way to achieve this goal is to apply computational methods based on ligands and target information. In this study, sixteen compounds with acceptable insecticidal activities, with 100% larvicidal activity at low concentrations (2.0 to 0.001 mg·L⁻¹), were selected from the literature. These compounds were used to build up and validate pharmacophore models. Pharmacophore model 6 (AUC = 0.78; BEDROC = 0.6) was used to filter 4793 compounds from the subset of lead-like compounds from the ZINC database; 4142 compounds (dG < 0 kcal/mol) were then aligned to the active site of the juvenile hormone receptor Aedes aegypti (PDB: 5V13), 2240 compounds (LE < −0.40 kcal/mol) were prioritized for molecular docking from the construction of a chitin deacetylase model of Aedes aegypti by the homology modeling of the Bombyx mori species (PDB: 5ZNT), which aligned 1959 compounds (dG < 0 kcal/mol), and 20 compounds (LE < −0.4 kcal/mol) were predicted for pharmacokinetic and toxicological prediction in silico (Preadmet, SwissADMET, and eMolTox programs). Finally, the theoretical routes of compounds M01, M02, M03, M04, and M05 were proposed. Compounds M01–M05 were selected, showing significant differences in pharmacokinetic and toxicological parameters in relation to positive controls and interaction with catalytic residues among key protein sites reported in the literature. For this reason, the molecules investigated here are dual inhibitors of the enzymes chitin synthase and juvenile hormonal protein from insects and humans, characterizing them as potential insecticides against the Aedes aegypti mosquito.     

Comparative Studies on the Extraction of Protactinium Using Different Kinds of Organic Extractants

Abstract

The extraction behavior of Pa(V) from various aqueous solutions was studied using different extractants, namely Amberlite-LA-2 (Amb-LA2), diethylhexyl phosphoric acid (HDEHP), tributylphosphate (TBP) and Tricaprylylmethyl ammonium chloride (TCMA) in toluene. The extraction was carried out from slightly acidic as well as strong acidic solutions of HCl, HBr, and HI, at various temperatures. The extracted species in every case were postulated. Extraction chromatography behavior of Pa(V), its homologue Nb(V), and the chemically similar elements Zr(IV) and Hf(IV) were also studied in the case of TCMA. Radioactive isotopes were used for tracing the corresponding elements. Some separation alternatives were achieved.     

Column Chromatography Using Nano-Sorbent: A Viable Approach Towards Post-Processing Concentration of 125I for Medical Applications

Successful use of ion-exchange chromatographic technique using nano-zirconia (t-ZrO₂), to concentrate ¹²⁵I solution obtained from wet chemical distillation method to levels required for preparation of ¹²⁵I brachytherapy sources, is reported. A careful scrutiny of the sorption parameters of t-ZrO₂ was carried out and implemented to arrive at conditions resulting in optimum retention of ¹²⁵I from its solution of low radioactive concentration on a tiny column containing t-ZrO₂, followed by its elution in a small volume of eluent. The developed procedure was validated using samples containing varying amounts of ¹²⁵I activity in the feed and the concentration factors (CF) of ¹²⁵I > 5 could be obtained. The overall recovery of ¹²⁵I was >90% with appropriate radiochemical purity. The compatibility of the product in the preparation of ¹²⁵I brachytherapy sources was found to be satisfactory.     

天然生态型腐植酸APEX-10对植物生长影响的比较研究

通过研究风化煤腐植酸钾、底泥腐植酸钾、褐煤黄腐酸钾、生化(物)黄腐酸、APEX-10等5种天然生态型腐植酸对小麦根系、茎生长的影响,并重点研究了APEX-10对不同植物生长的影响。得到如下结果:APEX-10对麦苗的生长促进作用、物质的积累以及持水能力的作用最佳,褐煤黄腐酸钾对小麦根部的生长促进作用最佳,风化煤腐植酸钾则对小麦根部的物质积累作用最佳。APEX-10与营养液复配施用于白菜时,不同的栽培方式其适宜浓度不一致。从经济、资源利用和效果等多个方面综合考虑,APEX-10对农作物和水果的最适宜浓度为75 mg/L。     

Effect of Different Particle Size Distributions on Solid-State Sintering: A Microscopic Simulation Approach

Simulations based on the discrete element method (DEM) are used to investigate the relationship between the distribution of particle sizes and the macroscopic sintering behavior of ceramic powders. This is achieved by generalizing the DEM force laws for solid-state sintering in such a way that sintering of particles with different sizes can be simulated. A generation scheme for initial particle packings with realistic physical properties is presented, which allows for different distributions, ranging from monomodal to normal, log-normal, and bimodal distributions. It is shown that the type and width of the distribution has a significant effect on the strain rates and viscosity during sintering. Broader size distributions lead to reduced sintering rates, although particle rearrangement is enhanced. However, the accelerating effect of rearrangement is overcompensated by an increase of the contact area between particles when the size distribution becomes wider. The simulation results are in good agreement with experimental results on a commercial Al₂O₃ power.     

分光光度法测定羟自由基的捕捉剂比较研究

研究了不同羟自由基捕捉剂的分光光度法,探讨了测定羟自由基的可靠、准确方法。利用具有清除·OH作用的抗坏血酸和谷胱甘肽,考察邻二氮菲、水杨酸、结晶紫、亚甲蓝作为·OH捕捉剂,用分光光度法测定·ON的可行性和可靠性。实验结果认为不确定的原因影响邻二氮菲和水杨酸法的测定结果,亚甲蓝法不可行,结晶紫测定结果合理,方法可行。在4种捕捉剂中,只有结晶紫测定·OH方法可靠,稳定性好,精密度高,可以用于测定羟自由基。     

A Cell-Based Approach to Dental Pulp Regeneration Using Mesenchymal Stem Cells: A Scoping Review

Despite the recent explosion of investigations on dental pulp regeneration using various tissue engineering strategies, the translation of the findings from such studies into therapeutic applications has not been properly achieved. The purpose of this scoping review was to systematically review the efficacy of mesenchymal stem cell transplantation for dental pulp regeneration. A literature search was conducted using five electronic databases from their inception to January 2021 and supplemented by hand searches. A total of 17 studies, including two clinical trials and 15 animal studies using orthotopic pulp regeneration models, were included for the review. The risk of bias for the individual studies was assessed. This scoping review demonstrated that the regeneration of vascularized pulp-like tissue was achieved using the stem cell transplantation strategy in animal models. Autologous cell transplantation in two clinical studies also successfully regenerated vascularized vital tissue. Dental pulp stem cell subpopulations, such as mobilized dental pulp stem cells, injectable scaffolds such as atelocollagen, and a granulocyte-colony forming factor, were the most commonly used for pulp regeneration. The overall risk of bias was unclear for animal studies and was moderate or judged to raise some concerns for clinical studies. More high-quality clinical studies are needed to further determine the safety and efficacy of the stem cell transplantation strategy for dental pulp regeneration.