Pharmaceuticals, Vol. 9, Pages 26: How Efficient Is My (Medicinal) Chemistry?

"Greening" a chemical transformation is not about only changing the nature of a solvent or decreasing the reaction temperature. There are metrics enabling a critical quantification of the efficiency of an experimental protocol. Some of them are applied to different sequences for the preparation of paracetamol in order to understand their performance parameters and elucidate pathways for improvement.

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Climate, Vol. 4, Pages 28: Disposition of Lightning Activity Due to Pollution Load during Dissimilar Seasons as Observed from Satellite and Ground-Based Data

The precise role of air pollution on the climate and local weather has been an issue for quite a long time. Among the diverse issues, the effects of air pollution on lightning are of recent interest. Exploration over several years (2004 to 2011) has been made over Gangetic West Bengal of India using lightning flash data from TRMM-LIS (Tropical Rainfall Measuring Mission-Lightning Imaging Sensor), atmospheric pollutants, and rainfall data during pre-monsoon (April and May) and monsoon (June, July, August and September) seasons. Near-surface pollutants such as PM10 and SO2 have a good positive association with aerosol optical depth (AOD) for both the pre-monsoon and monsoon months. High atmospheric aerosol loading correlates well with pre-monsoon and monsoon lightning flashes. However, rainfall has a dissimilar effect on lightning flashes. Flash count is positively associated with pre-monsoon rainfall (r = 0.64), but the reverse relation (r = −0.4) is observed for monsoon rainfall. Apart from meteorological factors, wet deposition of atmospheric pollutant may be considered a crucial factor for decreased lightning flash count in monsoon. The variation in the monthly average tropospheric column amount of NO2, from the Tropospheric Emission Monitoring Internet Service (TEMIS), is synchronic with average lightning flash rate. It has a good linear association with flash count for both pre-monsoon and monsoon seasons. The effect of lightning on tropospheric NO2 production is evident from the monthly average variation in NO2 on lightning and non-lightning days.

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IJGI, Vol. 5, Pages 68: Automatic and Accurate Conflation of Different Road-Network Vector Data towards Multi-Modal Navigation

With the rapid improvement of geospatial data acquisition and processing techniques, a variety of geospatial databases from public or private organizations have become available. Quite often, one dataset may be superior to other datasets in one, but not all aspects. In Germany, for instance, there were three major road network vector data, viz. Tele Atlas (which is now "TOMTOM"), NAVTEQ (which is now "here"), and ATKIS. However, none of them was qualified for the purpose of multi-modal navigation (e.g., driving + walking): Tele Atlas and NAVTEQ consist of comprehensive routing-relevant information, but many pedestrian ways are missing; ATKIS covers more pedestrian areas but the road objects are not fully attributed. To satisfy the requirements of multi-modal navigation, an automatic approach has been proposed to conflate different road networks together, which involves five routines: (a) road-network matching between datasets; (b) identification of the pedestrian ways; (c) geometric transformation to eliminate geometric inconsistency; (d) topologic remodeling of the conflated road network; and (e) error checking and correction. The proposed approach demonstrates high performance in a number of large test areas and therefore has been successfully utilized for the real-world data production in the whole region of Germany. As a result, the conflated road network allows the multi-modal navigation of "driving + walking".

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Energies, Vol. 9, Pages 364: How Much Detail Should We Use to Compute Societal Aggregated Exergy Efficiencies?

The current method used for calculating societal aggregated exergy efficiencies is reviewed. Cooling is introduced as an end-use category; conversion efficiencies for heating processes are obtained for each energy carrier; and electricity shares per end-use are retrieved for each sector, improving the accuracy of the estimated values of aggregated exergy efficiencies. We show that: (1) cooling uses are a relevant end-use in Portugal and that their introduction decreased overall efficiency by 3.4% in 2009; and (2) disaggregating the heating second law efficiencies for each energy carrier has a significant effect on the aggregated efficiencies of the country, decreasing aggregated efficiency by 1.3% in 2009. We studied two other factors that showed no significant impact on aggregated exergy efficiency: a technological lag of 10 years in the efficiency of stationary mechanical drive devices and the use of a year-specific ambient temperature to compute exergy efficiencies of heating processes.

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Low serum vitamin D is associated with higher cortical porosity in elderly men

Abstract

Background

Bone loss at peripheral sites in the elderly is mainly cortical and involves increased cortical porosity. However, an association between bone loss at these sites and 25-hydroxyvitamin D has not been reported.

Objective

To investigate the association between serum levels of 25-hydroxyvitamin D, bone microstructure and areal bone mineral density (BMD) in elderly men.

Methods

A population-based cohort of 444 elderly men (mean ± SD age 80.2 ± 3.5 years) was investigated. Bone microstructure was measured by high-resolution peripheral quantitative computed tomography, areal BMD by dual-energy X-ray absorptiometry and serum 25-hydroxyvitamin D and parathyroid hormone levels by immunoassay.

Results

Mean cortical porosity at the distal tibia was 14.7% higher (12.5 ± 4.3% vs. 10.9 ± 4.1%, P < 0.05) whilst cortical volumetric BMD, area, trabecular bone volume fraction and femoral neck areal BMD were lower in men in the lowest quartile of vitamin D levels compared to the highest. In men with vitamin D deficiency (<25 nmol L⁻¹) or insufficiency [25–49 nmol L⁻¹, in combination with an elevated serum level of parathyroid hormone (>6.8 pmol L⁻¹)], cortical porosity was 17.2% higher than in vitamin D-sufficient men (P < 0.01). A linear regression model including age, weight, height, daily calcium intake, physical activity, smoking vitamin D supplementation and parathyroid hormone showed that 25-hydroxyvitamin D independently predicted cortical porosity (standardized β = −0.110, R² = 1.1%, P = 0.024), area (β = 0.123, R² = 1.4%, P = 0.007) and cortical volumetric BMD (β = 0.125, R² = 1.4%, P = 0.007) of the tibia as well as areal BMD of the femoral neck (β = 0.102, R² = 0.9%, P = 0.04).

Conclusion

Serum vitamin D is associated with cortical porosity, area and density, indicating that bone fragility as a result of low vitamin D could be due to changes in cortical bone microstructure and geometry.

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Neurofibromatosis ophthalmic update

Abdolrahimzadeh B, Piraino DC, Albanese G, Cruciani F, Rahimi S

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Tear volume estimation using modified Schirmer test in dry eye patients

Miyake H, Kawano Y, Tanaka H, Iwata A, Imanaka T, Nakamura M

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Ocular manifestations of Sturge Weber syndrome

Mantelli F, Bruscolini A, La Cava M, Abdolrahimzadeh S, Lambiase A

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Cyclosporine effects on visual function in dry eye

Stonecipher KG, Torkildsen GL, Ousler III GW, Morris S, Villanueva L, Hollander DA

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Diverse Features of the Multiwavelength Afterglows of Gamma-Ray Bursts: Natural or Special?

The detection of optical rebrightenings and X-ray plateaus in the afterglows of gamma-ray bursts (GRBs) challenges the generic external shock model. Recently, we have developed a numerical method to calculate the dynamics of the system consisting of a forward shock and a reverse shock. Here, we briefly review the applications of this method in the afterglow theory. By relating these diverse features to the central engines of GRBs, we find that the steep optical rebrightenings would be caused by the fall-back accretion of black holes, while the shallow optical rebrightenings are the consequence of the injection of the electron-positron-pair wind from the central magnetar. These studies provide useful ways to probe the characteristics of GRB central engines.

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Increased levels of hyper-stable protein aggregates in plasma of older adults

Abstract

Proteins that misfold into hyper-stable/degradation-resistant species during aging may accumulate and disrupt protein homeostasis (i.e., proteostasis), thereby posing a survival risk to any organism. Using the method diagonal two-dimensional (D2D) SDS-PAGE, which separates hyper-stable SDS-resistant proteins at a proteomics level, we analyzed the plasma of healthy young (<30 years) and older (60–80 years) adults. We discovered the presence of soluble SDS-resistant protein aggregates in the plasma of older adults, but found significantly lower levels in the plasma of young adults. We identified the inflammation-related chaperone protein haptoglobin as the main component of the hyper-stable aggregates. This observation is consistent with the growing link between accumulations of protein aggregates and aging across many organisms. It is plausible higher amounts of SDS-resistant protein aggregates in the plasma of older adults may reflect a compromise in proteostasis that may potentially indicate cellular aging and/or disease risk. The results of this study have implications for further understanding the link between aging and the accumulation of protein aggregates, as well as potential for the development of aging-related biomarkers. More broadly, this novel application of D2D SDS-PAGE may be used to identify, quantify, and characterize the degradation-resistant protein aggregates in human plasma or any biological system.

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Biological characterization of the hygrobafilomycin antibiotic JBIR-100 and bioinformatic insights into the hygrolide family of natural products

Publication date: Available online 14 May 2016
Source:Bioorganic & Medicinal Chemistry
Author(s): Evelyn M. Molloy, Jonathan I. Tietz, Patricia M. Blair, Douglas A. Mitchell
The hygrolides, a family of 16-member-ring-containing plecomacrolides produced by Actinobacteria, exhibit numerous reported bioactivities. Using HR-MS/MS, nucleophilic 1,4-addition-based labeling, NMR, and bioinformatic analysis, we identified Streptomyces varsoviensis as a novel producer of JBIR-100, a fumarate-containing hygrolide, and elucidated the previously unknown stereochemistry of the natural product. We investigated the antimicrobial activity of JBIR-100, with preliminary insight into mode of action indicating that it perturbs the membrane of Bacillus subtilis. S. varsoviensis is known to produce compounds from multiple hygrolide sub-families, namely hygrobafilomycins (JBIR-100 and hygrobafilomycin) and bafilomycins (bafilomycin C1 and D). In light of this, we identified the biosynthetic gene cluster for JBIR-100, which, to our knowledge, represents the first reported for a hygrobafilomycin. Finally, we performed a bioinformatic analysis of the hygrolide family, describing clusters from known and predicted producers. Our results indicate that potential remains for the Actinobacteria to yield novel hygrolide congeners, perhaps with differing biological activities.

Graphical abstract

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An In-depth Cognitive Examination of Individuals with Superior Face Recognition Skills

Publication date: Available online 15 May 2016
Source:Cortex
Author(s): Anna K. Bobak, Rachel J. Bennetts, Benjamin A. Parris, Ashok Jansari, Sarah Bate
Previous work has reported the existence of "super-recognisers" (SRs), or individuals with extraordinary face recognition skills. However, the precise underpinnings of this ability have not yet been investigated. In this paper we examine (a) the face-specificity of super recognition, (b) perception of facial identity in SRs, (c) whether SRs present with enhancements in holistic processing and (d) the consistency of these findings across different SRs. A detailed neuropsychological investigation into six SRs indicated domain-specificity in three participants, with some evidence of enhanced generalised visuo-cognitive or socio-emotional processes in the remaining individuals. While superior face-processing skills were restricted to face memory in three of the SRs, enhancements to facial identity perception were observed in the others. Notably, five of the six participants showed at least some evidence of enhanced holistic processing. These findings indicate cognitive heterogeneity in the presentation of superior face recognition, and have implications for our theoretical understanding of the typical face-processing system and the identification of superior face-processing skills in applied settings.



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Indacaterol–Glycopyrronium versus Salmeterol–Fluticasone for COPD

Exacerbations of chronic obstructive pulmonary disease (COPD) are associated with an accelerated decline in lung function, impaired quality of life, hospitalization, and increased mortality. COPD exacerbations are costly to health care systems. Thus, prevention of exacerbations is a key goal in the…

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Impacts of Nonsynonymous Single Nucleotide Polymorphisms of Adiponectin Receptor 1 Gene on Corresponding Protein Stability: A Computational Approach

Despite the reported association of adiponectin receptor 1 (ADIPOR1) gene mutations with vulnerability to several human metabolic diseases, there is lack of computational analysis on the functional and structural impacts of single nucleotide polymorphisms (SNPs) of the human ADIPOR1 at protein level. Therefore, sequence- and structure-based computational tools were employed in this study to functionally and structurally characterize the coding nsSNPs of ADIPOR1 gene listed in the dbSNP database. Our in silico analysis by SIFT, nsSNPAnalyzer, PolyPhen-2, Fathmm, I-Mutant 2.0, SNPs&GO, PhD-SNP, PANTHER, and SNPeffect tools identified the nsSNPs with distorting functional impacts, namely, rs765425383 (A348G), rs752071352 (H341Y), rs759555652 (R324L), rs200326086 (L224F), and rs766267373 (L143P) from 74 nsSNPs of ADIPOR1 gene. Finally the aforementioned five deleterious nsSNPs were introduced using Swiss-PDB Viewer package within the X-ray crystal structure of ADIPOR1 protein, and changes in free energy for these mutations were computed. Although increased free energy was observed for all the mutants, the nsSNP H341Y caused the highest energy increase amongst all. RMSD and TM scores predicted that mutants were structurally similar to wild type protein. Our analyses suggested that the aforementioned variants especially H341Y could directly or indirectly destabilize the amino acid interactions and hydrogen bonding networks of ADIPOR1.

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Simultaneous Minimally Invasive Treatment of Colorectal Neoplasm with Synchronous Liver Metastasis

Purpose. To analyse perioperative and oncological outcomes of minimally invasive simultaneous resection of primary colorectal neoplasm with synchronous liver metastases. Methods. A Medline revision of the current published literature on laparoscopic and robotic-assisted combined colectomy with hepatectomy for synchronous liver metastatic colorectal neoplasm was performed until February 2015. The specific search terms were "liver metastases", "hepatic metastases", "colorectal", "colon", "rectal", "minimally invasive", "laparoscopy", "robotic-assisted", "robotic colorectal and liver resection", "synchronous", and "simultaneous". Results. 20 clinical reports including 150 patients who underwent minimally invasive one-stage procedure were retrospectively analysed. No randomized trials were found. The approach was laparoscopic in 139 patients (92.7%) and robotic in 11 cases (7.3%). The rectum was the most resected site of primary neoplasm (52.7%) and combined liver procedure was in 89% of cases a minor liver resection. One patient (0.7%) required conversion to open surgery. The overall morbidity and mortality rate were 18% and 1.3%, respectively. The most common complication was colorectal anastomotic leakage. Data concerning oncologic outcomes were too heterogeneous in order to gather definitive results. Conclusion. Although no prospective randomized trials are available, one-stage minimally invasive approach seems to show advantages over conventional surgery in terms of postoperative short-term course. On the contrary, more studies are required to define the oncologic values of the minimally invasive combined treatment.

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DNA polymerase θ (POLQ), double-strand break repair, and cancer

Publication date: Available online 14 May 2016
Source:DNA Repair
Author(s): Richard D. Wood, Sylvie Doublié
DNA polymerase theta (pol θ) is encoded in the genomes of many eukaryotes, though not in fungi. Pol θ is encoded by the POLQ gene in mammalian cells. The C-terminal third of the protein is a family A DNA polymerase with additional insertion elements relative to prokaryotic homologs. The N-terminal third is a helicase-like domain with DNA-dependent ATPase activity. Pol θ is important in the repair of genomic double-strand breaks (DSBs) from many sources. These include breaks formed by ionizing radiation and topoisomerase inhibitors, breaks arising at stalled DNA replication forks, breaks introduced during diversification steps of the mammalian immune system, and DSB induced by CRISPR-Cas9. Pol θ participates in a route of DSB repair termed "alternative end-joining" (altEJ). AltEJ is independent of the DNA binding Ku protein complex and requires DNA end resection. Pol θ is able to mediate joining of two resected 3′ ends harboring DNA sequence microhomology. "Signatures" of Pol θ action during altEJ are the frequent utilization of longer microhomologies, and the insertion of additional sequences at joining sites. The mechanism of end-joining employs the ability of Pol θ to tightly grasp a 3′ terminus through unique contacts in the active site, allowing extension from minimally paired primers. Pol θ is involved in controlling the frequency of chromosome translocations and preserves genome integrity by limiting large deletions. It may also play a backup role in DNA base excision repair. POLQ is a member of a cluster of similarly upregulated genes that are strongly correlated with poor clinical outcome for breast cancer, ovarian cancer and other cancer types. Inhibition of pol θ is a compelling approach for combination therapy of radiosensitization.



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NADPH oxidase 4 deficiency leads to impaired wound repair and reduced dityrosine-crosslinking, but does not affect myofibroblast formation

Publication date: July 2016
Source:Free Radical Biology and Medicine, Volume 96
Author(s): Dominik Lévigne, Ali Modarressi, Karl-Heinz Krause, Brigitte Pittet-Cuénod
NADPH oxidases (NOX) mediate redox signaling by generating superoxide and/or hydrogen peroxide, which are involved in biosynthetic pathways, e.g. thyroid hormone generation, dityrosine crosslinking, as well as bacterial killing. Data investigating the role of NOX enzymes in cutaneous wound repair is limited and specifically their function in skin myofibroblast expression is unknown. The isoform NOX4 was recently shown to be a pre-requisite for the differentiation of cardiac and pulmonary myofibroblasts.In this study we investigate the role of NOX4 in wound repair using a wound model in NOX4 knockout mice (n=16) and wildtype mice (n=16). Wounds were photographed daily until complete wound closure. Mice were sacrificed at day 3, 7, 14; wound tissue was harvested.NOX4-deficient mice healed significantly slower (22 days, SD=1.9) than wild-type mice (17 days, SD=1.4, p<0.005). However, there was no difference in myofibroblast expression. Strong dityrosine formation was observed, but was significantly weaker in NOX4-/- mice (p<0.05). NOX2, HIF1α and CD31 expression was significantly weaker in NOX4-/- mice (p<0.05).In this study we show for the first time that NOX4 plays a role in cutaneous wound repair. Our data suggests that NOX4 mediates HIF1α expression and neoangiogenesis during wound repair. NOX4 deletion led to a decreased expression of NOX2, implying a role of NOX4 in phagocytic cell recruitment. NOX4 was required for effective wound contraction but not myofibroblast expression. We suggest that myofibroblast contraction in NOX4-deficient mice is less effective in contracting the wound because of insufficient dityrosine-crosslinking of the ECM, providing the first indication for a physiological function of dityrosine crosslinking in higher animals.



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Immunological Evasion in Glioblastoma

Glioblastoma is the most aggressive tumor in Central Nervous System in adults. Among its features, modulation of immune system stands out. Although immune system is capable of detecting and eliminating tumor cells mainly by cytotoxic T and NK cells, tumor microenvironment suppresses an effective response through recruitment of modulator cells such as regulatory T cells, monocyte-derived suppressor cells, M2 macrophages, and microglia as well as secretion of immunomodulators including IL-6, IL-10, CSF-1, TGF-β, and CCL2. Other mechanisms that induce immunosuppression include enzymes as indolamine 2,3-dioxygenase. For this reason it is important to develop new therapies that avoid this immune evasion to promote an effective response against glioblastoma.

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Improvement of the Texture of Yogurt by Use of Exopolysaccharide Producing Lactic Acid Bacteria

19 Streptococcus thermophilus with high exopolysaccharide production were isolated from traditional Chinese fermented dairy products. The exopolysaccharide and viscosity of milk fermented by these 19 isolates were assayed. The strains of Streptococcus thermophilus zlw TM11 were selected because its fermented milk had the highest exopolysaccharide content (380 mg/L) and viscosity (7716 mpa/s). Then Streptococcus thermophilus zlw TM11 was combined with Lactobacillus delbrueckii subsp. bulgaricus 3 4.5 and the combination was named SH-1. The quality of the yogurt fermented by SH-1 and two commercial starter cultures (YO-MIX 465, YF-L711) were compared. It was shown that the exopolysaccharide content of yogurt fermented by SH-1 was similar to that of yogurt fermented by YF-L711 and significantly higher than YO-MIX 465 (). In addition, the yogurt fermented by SH-1 had the lowest syneresis (8.5%) and better texture and sensory than the samples fermented by YO-MIX 465 and YF-L711. It manifested that the selected higher exopolysaccharide production starter SH-1 could be used as yogurt starter and reduce the amount of adding stabilizer, which can compare with the imported commercial starter culture.

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Evaluation of Risk Factors for Peste des Petits Ruminants Virus in Sheep and Goats at the Wildlife-Livestock Interface in Punjab Province, Pakistan

Peste des petits ruminants virus (PPRV) is causing infectious disease with high morbidity and mortality rate in domestic and wild small ruminants of Pakistan with valuable economical losses. The present study was carried out to investigate risk factors of PPRV in domestic small ruminants which were present in the vicinity of wildlife parks. A total of 265 sera samples (27 wild ruminants and 238 domesticated small ruminants) from apparently healthy animals from two different wildlife parks were collected and analysed for PPRV antibodies. Also, 20 nasal swabs from domestic small ruminants showing respiratory signs were collected to check for presence of PPRV antigen. Competitive ELISA revealed highest proportions of anti-PPRV antibodies in domestic small ruminants around the Wildlife Park at Lahore (35%) as compared to Faisalabad (13%), with no existence of PPRV antibodies in tested serum of wild ruminants at these parks. Higher seropositivity was observed in females (25.6%) than in males (5.1%) and in goats (34.5%) compared to sheep (11.2%). The results of N-gene based RT-PCR highlight the absence of PPRV due to lack of current PPR outbreak in the region during study period. Even though grazing was not a significant risk factor, there is still a possibility of wildlife-livestock interactions for feed and water reservoirs, resulting in spillover of PPR to wildlife. Keeping in view the high seropositivity and risk of PPR, vaccination should be adopted to avoid circulation of PPRV among wild and domestic small ruminants (sheep and goats).

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A case study of SMART attributes: a qualitative assessment of generalizability, retention rate, and trial quality

Personalizing medical care is becoming increasingly popular, particularly mental health care. There is growing interest in formalizing medical decision making based on evolving patient symptoms in an evidence-...

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Efficacy of transcranial direct-current stimulation (tDCS) in women with provoked vestibulodynia: study protocol for a randomized controlled trial

Provoked vestibulodynia is the most common form of vulvodynia. Despite its high prevalence and deleterious sexual, conjugal, and psychological repercussions, effective evidence-based interventions for provoked...

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Determination of phytate in high molecular weight, charged organic matrices by two-dimensional size exclusion-ion chromatography

Publication date: 15 August 2016
Source:Talanta, Volumes 156–157
Author(s): Kyle R. Elkin, Rosanne Slingsby, Ray B. Bryant
A two-dimensional chromatography method for analyzing phytate or other ionic targets in matrices containing high molecular weight, charged organic species is described. Prior to quantification by anion exchange chromatography, the sample matrix was prepared by size exclusion chromatography, which removed the majority of the matrix. Quantification of phytate on the AS11-HC was sensitive (0.25µM, 0.17mg/l) and reproducible (4.6% RSD) allowing this method to provide baseline separation of phytate from a manure extract within 14min. The method is simple, requiring only sample filtering, reproducible (between-run variation 5% RSD) and linear from 0.38 to 76µM (0.25–50mg/l). The method is suitable for routine determination of phytate in high organic matrices such as manure extracts.

Graphical abstract

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Rapid estimation of readily leachable triazine residues in soils using automatic kinetic bioaccessibility assays followed by on-line sorptive clean-up as a front-end to liquid chromatography

Publication date: 15 August 2016
Source:Talanta, Volumes 156–157
Author(s): Ana C.F. Vida, David J. Cocovi-Solberg, Elias A.G. Zagatto, Manuel Miró
An automatic batchwise bioaccessibility test was proposed for on-line monitoring of readily mobile pools of ametryn and atrazine residues in agricultural soils with different physicochemical properties. A 0.01molL⁻¹ CaCl2 solution mimicking rainwater percolation through the soil profiles was used for the herbicide extractions. The extract aliquots were successively sampled at regular time intervals in order to investigate the extraction kinetics. For extract clean-up and retention of freely dissolved target species, 30mg of restricted-access like copolymer were used as in-line sorptive material followed by elution with methanol and on-line heart-cut injection towards a C18 silica reversed-phase monolithic column (100×4.6mm) in a liquid chromatographic system. A mathematical model emphasized that the readily available pools vs time can be in most instances described by a first-order exponential equation, thus an asymptotical value is approached. Consequently, the leaching assays can be performed without attaining chemical equilibrium. Enhancement factors and detection limits were 10.2 and 18.8, and 0.40 and 0.37mgkg⁻¹ for ametryn and atrazine, respectively. The automatic method features good repeatability for leaching tests (r.s.d.: 11.8−10.2% for sandy and 3.7–6.2% for clayey soil). Reliable data, demonstrated with relative recoveries in the soil leachates ranging from 86 to 104%, were achieved in less than 35min, thus avoiding the need for up to 24h as recommended by standard leaching methods.

Graphical abstract

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New optical paper sensor for in situ measurement of hydrogen sulphide in waters and atmospheres

Publication date: 15 August 2016
Source:Talanta, Volumes 156–157
Author(s): J. Pla-Tolós, Y. Moliner-Martínez, J. Verdú-Andrés, J. Casanova-Chafer, C. Molins-Legua, P. Campíns-Falcó
A novel and low-cost colorimetric sensor for the determination of hydrogen sulphide in environmental samples has been developed. This sensor is based on the immobilization of the reagent N,N-Dimethyl-p-phenylenediamine and FeCl3 in paper support, in which the H2S is adsorbed in order to give rise to the formation of methylene blue as reaction product.The sensor has been applied to determine H2S in water and air samples. Two different sampling systems for H2S caption from the air have been assayed: active and passive sampling. The analytical properties of the different systems have been obtained and compared. The analytical signals, corresponding to the methylene blue, have been obtained measuring the absorbance by conventional reflectance diffuse or using different algorithms for quantifying color intensity. The results obtained with both measurement procedures were comparable, with a detection limit of 1.11 and 1.12mLm⁻³ for air samples (active and passive), and 0.5mgL⁻¹ for water samples. The developed sensor provides good accuracy and precision (RSD<12%) and simplifies significantly the analytical measurements because it avoids the need of preparing derivatization reagents, sample handling and allows in situ measurements. The reaction product obtained is highly stable in this support and no provide any blank signal. Under the optimal conditions, the proposed method exhibit excellent visual sensitivity for the naked eye procedure, making the detection of H2S possible.

Graphical abstract

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Bio-assisted potentiometric multisensor system for purity evaluation of recombinant protein A

Publication date: 15 August 2016
Source:Talanta, Volumes 156–157
Author(s): Edita Voitechovič, Anton Korepanov, Dmitry Kirsanov, Igor Jahatspanian, Andrey Legin
Recombinant proteins became essential components of drug manufacturing. Quality control of such proteins is routine task, which usually requires a lot of time, expensive reagents, specialized equipment and highly educated personnel. In this study we propose a new concept for protein purity evaluation that is based on application of bio-assisted potentiometric multisensor system. The model object for analysis was recombinant protein A from Staphylococcus aureus (SpA), which is commonly used for monoclonal antibody purification. SpA solutions with different amount of host cell related impurities (Escherichia coli, bacterial lysate) were analyzed. Two different bio-transducers were employed: proteinase K from Tritirachium album and baker's yeast Saccharomyces cerevisiae. It was shown that both bio-transducers are able to induce changes in pure and lysate-contaminated SpA samples. Different products of yeast digestion and proteolysis with proteinase of pure SpA and lysate were detected with size exclusion high-performance liquid chromatography (SE-HPLC). The induced changes of chemical composition are detectible with potentiometric multisensor system and can be related to SpA purity through projection on latent structures (PLS) regression technique. The proposed method allows for estimation of the impurity content with 12% accuracy using proteinase K and 16% accuracy using baker's yeast. The suggested approach could be useful for early contamination warning at initial protein purification steps. The analysis requires no expensive materials and equipment, no bio-material immobilization, and its duration time is comparable with other commonly used methods like chromatography or electrophoresis though the main part of this time is related to the sample preparation.

Graphical abstract

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Comparison of the solid-phase extraction efficiency of a bounded and an included cyclodextrin-silica microporous composite for polycyclic aromatic hydrocarbons determination in water samples

Publication date: 15 August 2016
Source:Talanta, Volumes 156–157
Author(s): Adela Mauri-Aucejo, Pedro Amorós, Alaina Moragues, Carmen Guillem, Carolina Belenguer-Sapiña
Solid-phase extraction is one of the most important techniques for sample purification and concentration. A wide variety of solid phases have been used for sample preparation over time. In this work, the efficiency of a new kind of solid-phase extraction adsorbent, which is a microporous material made from modified cyclodextrin bounded to a silica network, is evaluated through an analytical method which combines solid-phase extraction with high-performance liquid chromatography to determine polycyclic aromatic hydrocarbons in water samples. Several parameters that affected the analytes recovery, such as the amount of solid phase, the nature and volume of the eluent or the sample volume and concentration influence have been evaluated. The experimental results indicate that the material possesses adsorption ability to the tested polycyclic aromatic hydrocarbons. Under the optimum conditions, the quantification limits of the method were in the range of 0.09–2.4μgL⁻¹ and fine linear correlations between peak height and concentration were found around 1.3–70μgL⁻¹. The method has good repeatability and reproducibility, with coefficients of variation under 8%. Due to the concentration results, this material may represent an alternative for trace analysis of polycyclic aromatic hydrocarbons in water trough solid-phase extraction.

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Ultra-trace level speciated isotope dilution measurement of Cr(VI) using ion chromatography tandem mass spectrometry in environmental waters

Publication date: 15 August 2016
Source:Talanta, Volumes 156–157
Author(s): Stefanie Mädler, Aaron Todd, H.M. "Skip" Kingston, Matt Pamuku, Fengrong Sun, Cindy Tat, Robert J. Tooley, Teresa A. Switzer, Vasile I. Furdui
The reliable analysis of highly toxic hexavalent chromium, Cr(VI), at ultra-trace levels remains challenging, given its easy conversion to non-toxic trivalent chromium. This work demonstrates a novel analytical method to quantify Cr(VI) at low ngL⁻¹ concentration levels in environmental water samples by using speciated isotope dilution (SID) analysis and double-spiking with Cr(III) and Cr(VI) enriched for different isotopes. Ion chromatography tandem mass spectrometry (IC-MS/MS) was used for the analysis of Cr(VI) as HCrO4⁻ → CrO3⁻. Whereas the classical linear multipoint calibration (MPC) curve approach obtained a method detection limit (MDL) of 7ngL⁻¹ Cr(VI), the modified SID-MS method adapted from U. S. EPA 6800 allowed for the quantification of Cr(VI) with an MDL of 2ngL⁻¹ and provided results corrected for Cr(VI) loss occurred after sample collection. The adapted SID-MS approach proved to yield more accurate and precise results than the MPC method, allowed for compensation of Cr(VI) reduction during sample transportation and storage while eliminating the need for frequent external calibration. The developed method is a complementary tool to routinely used inductively-coupled plasma (ICP) MS and circumvents typically experienced interferences.

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A single use electrochemical sensor based on biomimetic nanoceria for the detection of wine antioxidants

Publication date: 15 August 2016
Source:Talanta, Volumes 156–157
Author(s): Veronica Andrei, Erica Sharpe, Alina Vasilescu, Silvana Andreescu
We report the development and characterization of a disposable single use electrochemical sensor based on the oxidase-like activity of nanoceria particles for the detection of phenolic antioxidants. The use of nanoceria in the sensor design enables oxidation of phenolic compounds, particularly those with ortho-dihydroxybenzene functionality, to their corresponding quinones at the surface of a screen printed carbon electrode. Detection is carried out by electrochemical reduction of the resulting quinone at a low applied potential of −0.1V vs the Ag/AgCl electrode. The sensor was optimized and characterized with respect to particle loading, applied potential, response time, detection limit, linear concentration range and sensitivity. The method enabled rapid detection of common phenolic antioxidants including caffeic acid, gallic acid and quercetin in the µM concentration range, and demonstrated good functionality for the analysis of antioxidant content in several wine samples. The intrinsic oxidase-like activity of nanoceria shows promise as a robust tool for sensitive and cost effective analysis of antioxidants using electrochemical detection.

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Application of a nanostructured platform and imprinted sol-gel film for determination of chlorogenic acid in food samples

Publication date: 15 August 2016
Source:Talanta, Volumes 156–157
Author(s): Carla M. Ribeiro, Eliane M. Miguel, Jonadab dos S. Silva, Cristian B. da Silva, Marília O.F. Goulart, Lauro T. Kubota, Fabiano B. Gonzaga, Wilney J.R. Santos, Phabyanno R. Lima
Chlorogenic acid (CGA) is a polyphenol derivative that widely exists in higher plants like fruits, vegetables, black teas, and some traditional Chinese medicines. In this work, we have proposed a sensitive and selective electrochemical sensor for detection of CGA. The sensor was based on a glassy carbon electrode (GCE) modified with a functional platform by grafting vinyltrimethoxysilane (VTMS) in multi-walled carbon nanotubes (MWCNTs) and covered by a molecularly imprinted siloxane (MIS) film prepared using the sol-gel process. The VTMS was grafted onto the surface of the MWCNTs via in situ free radical polymerization. The MIS was obtained from the acid-catalyzed hydrolysis/condensation of a solution consisting of tetraethoxysilane (TEOS), phenyltriethoxysilane (PTEOS), (3-aminopropyl)trimethoxysilane (APTMS), and CGA as a template molecule. The modification procedure was evaluated by differential pulse voltammetry (DPV) and scanning electron microscopy (SEM). Under optimized operational conditions, a linear response was obtained covering a concentration ranging from 0.08μmolL⁻¹ to 500μmolL⁻¹ with a detection limit (LOD) of 0.032μmolL⁻¹. The proposed sensor was applied to CGA determination in coffee, tomato, and apple samples with recoveries ranging from 99.3% to 108.6%, showing a promising potential application in food samples. Additionally, the imprinted sensor showed a significantly higher affinity for target CGA than the non-imprinted siloxane (NIS) sensor.

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Polydimethylsiloxane/metal-organic frameworks coated stir bar sorptive extraction coupled to gas chromatography-flame photometric detection for the determination of organophosphorus pesticides in environmental water samples

Publication date: 15 August 2016
Source:Talanta, Volumes 156–157
Author(s): Zuowei Xiao, Man He, Beibei Chen, Bin Hu
In this work, the metal-organic frameworks (MOFs), MIL-101-Cr-NH2 was synthesized via a direct hydrothermal method, and a polydimethylsiloxane (PDMS)/MIL-101-Cr-NH2 coated stir bar was prepared by sol-gel technique. Good reproducibility was obtained for the preparation of PDMS/MIL-101-Cr-NH2 coated stir bar with the relative standard deviations (RSDs) ranging from 3.7 to 5.2% (n=7) in one batch, and from 5.4 to 9.2% (n=7) among different batches. With the high surface area and rich benzene ring structure of MIL-101-Cr-NH2, the prepared PDMS/MIL-101-Cr-NH2 coated stir bar presented higher extraction efficiency for target organophosphorus pesticides (OPPs, including phorate, diazinon, malathion, fenthion, quinalphos and ethion) over PDMS coated stir bar. Based on it, a new method of PDMS/MIL-101-Cr-NH2 coated stir bar sorptive extraction (SBSE) coupled to gas chromatography-flame photometric detection (GC-FPD) was proposed for the determination of six OPPs in environmental water samples. The operation parameters affecting the extraction efficiency of SBSE, including extraction time, stirring rate, desorption time and ionic strength, were investigated. Under the optimal conditions, the limits of detection (S/N=3) were found to be in the range of 0.043–0.085μgL⁻¹ for the six target OPPs, and the linear range was 0.5–100μgL⁻¹ for malathion and 0.2–100μgL⁻¹ for other five OPPs. The RSDs of the proposed method evaluated at 1µgL⁻¹ for each OPP were in the range of 5.9–8.7% (intra-day, n=7) and 6.1–10.7% (inter-day, n=5), respectively. The enrichment factors were varied from 110 to 151-fold (theoretical enrichment factor was 200-fold). The proposed method was applied to the analysis of OPPs in East Lake and pond water samples with recoveries in the range of 89.3–115% and 80.0–113% for the spiked East Lake and pond water samples, respectively.

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