bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of long‐term Holocene soil erosion rates in Polish loess areas using sedimentary archives from closed depressions
Authors: Kołodyńska‐Gawrysiak Renata , Poesen Jean , Gawrysiak Leszek
Published: November 2017

Soil erosion is a particularly important problem in the loess areas of Central Europe. Numerous studies of past and present soil erosion based on colluvial sediments have so far been conducted. The main problem is the fact that colluvia usually do not represent the complete sedimentation record. Closed depressions (CDs) collect all colluvial sediments from their catchment, therefore, constitute sediment stores enabling the calculation of soil erosion rates.

Colluvial sediments and fossil soils, infilling four CDs in the Polish loess belt, were OSL and C‐14 dated. Human settlements near the studied CDs were analyzed. Phases of soil erosion and colluviation from the Neolithic (5400–2900 bc), from the Middle Bronze Age to the Early Iron Age (1600–0 bc), and from the Early Middle Ages to Modern Times (500 AD until today) were documented within the CDs studied. Phases of low soil erosion rate and pedogenesis occurred from the Late Vistulian to the Early Neolithic and from the Iron Age to Early Middle Ages. This study reveals that these phases are not synchronous with the soil erosion phases in Central Europe, as the latter mainly occurred in the Bronze Age, Roman Period and Middle Ages. The obtained soil erosion rates were compared with erosion rates in different areas of Central Europe. This study indicates that in loess regions with long‐term agricultural land use, mean erosion rates (i.e. 3.7–5.9 t ha‐1 yr‐1) from the Middle Ages to Modern Times were ten times higher than during the entire prehistoric period (0.39–0.67 t ha‐1 yr‐1). The mean soil erosion rates for forested CDs was 0.24–0.74 t ha‐1 yr‐1.

Soil erosion phases are most probably caused by human activities (i.e. land use change) but the early Holocene erosion phase (7.96 +/‐ 0.67 kyr) could have been induced by a climatic fluctuation (e.g. a 8.2 kyr Bond event). Copyright © 2018 John Wiley & Sons, Ltd.
Metal‐coordinated epoxy polymers with suppressed combustibility. Preparation technology, thermal degradation, and combustibility test of new epoxy‐amine polymers containing the curing agent with chelated copper(II) carbonate
Authors: Lavrenyuk Helen , Kochubei Victoria , Mykhalichko Oleg , Mykhalichko Borys
Published: November 2017

The diethylenetriamine chelate complex of copper(II) carbonate—DETA‐CuCO3 (a fire retardant hardener of epoxy resins)—and the CuCO3‐containing epoxy‐amine polymers—DGEBA/DETA‐CuCO3(6), DGEBA/DETA‐CuCO3(12), DGEBA/DETA‐CuCO3(40), and DGEBA/DETA‐CuCO3(80) with suppressed combustibility—have been obtained in the DETA‐DGEBA‐CuCO3 system (DETA and DGEBA are diethylenetriamine and bisphenol A diglycidyl ether, respectively). The DETA‐CuCO3 chelate complex was characterized by X‐ray powder diffraction, infrared spectra, and thermal analysis. The thermal gravimetric analysis results have revealed that thermal destruction of DETA‐CuCO3 was finished at 400°С, and the maximal temperature of the combustion gases amounted to 520°С. The thermal behavior and combustibility of the CuCO3‐containing epoxy‐amine polymers were studied using thermal analysis and “Ceramic tube” (CT) method. Thermal gravimetric analysis confirms that incorporation of the DETA‐CuCO3 into DGEBA appreciably heightens the thermal stability and antiflammability of the CuCO3‐containing epoxy‐amine polymers. Results of CT measurement reveal that maximal temperature of the combustion gases under burning of the DGEBA/DETA‐CuCO3(12) sample in comparison with unmodified epoxy‐amine polymer (DGEBA/DETA) is lowered on 219°С and the loss of weight is decreased on 20.5 wt%. According to ASTM 635‐14, ASTM D2863‐13, and ASTM D1929‐16, the flame propagation rate, limiting oxygen index, and temperatures of ignition and self‐ignition have been measured for the elaborated polymer samples.
Predictive accuracy of combined genetic and environmental risk scores
Authors: Dudbridge Frank , Pashayan Nora , Yang Jian
Published: November 2017

The substantial heritability of most complex diseases suggests that genetic data could provide useful risk prediction. To date the performance of genetic risk scores has fallen short of the potential implied by heritability, but this can be explained by insufficient sample sizes for estimating highly polygenic models. When risk predictors already exist based on environment or lifestyle, two key questions are to what extent can they be improved by adding genetic information, and what is the ultimate potential of combined genetic and environmental risk scores? Here, we extend previous work on the predictive accuracy of polygenic scores to allow for an environmental score that may be correlated with the polygenic score, for example when the environmental factors mediate the genetic risk. We derive common measures of predictive accuracy and improvement as functions of the training sample size, chip heritabilities of disease and environmental score, and genetic correlation between disease and environmental risk factors. We consider simple addition of the two scores and a weighted sum that accounts for their correlation. Using examples from studies of cardiovascular disease and breast cancer, we show that improvements in discrimination are generally small but reasonable degrees of reclassification could be obtained with current sample sizes. Correlation between genetic and environmental scores has only minor effects on numerical results in realistic scenarios. In the longer term, as the accuracy of polygenic scores improves they will come to dominate the predictive accuracy compared to environmental scores.
Using imputed genotype data in the joint score tests for genetic association and gene–environment interactions in case‐control studies
Authors: Song Minsun , Wheeler William , Caporaso Neil E. , Landi Maria Teresa , Chatterjee Nilanjan
Published: November 2017

Genome‐wide association studies (GWAS) are now routinely imputed for untyped single nucleotide polymorphisms (SNPs) based on various powerful statistical algorithms for imputation trained on reference datasets. The use of predicted allele counts for imputed SNPs as the dosage variable is known to produce valid score test for genetic association. In this paper, we investigate how to best handle imputed SNPs in various modern complex tests for genetic associations incorporating gene–environment interactions. We focus on case‐control association studies where inference for an underlying logistic regression model can be performed using alternative methods that rely on varying degree on an assumption of gene–environment independence in the underlying population. As increasingly large‐scale GWAS are being performed through consortia effort where it is preferable to share only summary‐level information across studies, we also describe simple mechanisms for implementing score tests based on standard meta‐analysis of “one‐step” maximum‐likelihood estimates across studies. Applications of the methods in simulation studies and a dataset from GWAS of lung cancer illustrate ability of the proposed methods to maintain type‐I error rates for the underlying testing procedures. For analysis of imputed SNPs, similar to typed SNPs, the retrospective methods can lead to considerable efficiency gain for modeling of gene–environment interactions under the assumption of gene–environment independence. Methods are made available for public use through CGEN R software package.
A unified partial likelihood approach for X‐chromosome association on time‐to‐event outcomes
Authors: Xu Wei , Hao Meiling
Published: November 2017

The expression of X‐chromosome undergoes three possible biological processes: X‐chromosome inactivation (XCI), escape of the X‐chromosome inactivation (XCI‐E), and skewed X‐chromosome inactivation (XCI‐S). Although these expressions are included in various predesigned genetic variation chip platforms, the X‐chromosome has generally been excluded from the majority of genome‐wide association studies analyses; this is most likely due to the lack of a standardized method in handling X‐chromosomal genotype data. To analyze the X‐linked genetic association for time‐to‐event outcomes with the actual process unknown, we propose a unified approach of maximizing the partial likelihood over all of the potential biological processes. The proposed method can be used to infer the true biological process and derive unbiased estimates of the genetic association parameters. A partial likelihood ratio test statistic that has been proved asymptotically chi‐square distributed can be used to assess the X‐chromosome genetic association. Furthermore, if the X‐chromosome expression pertains to the XCI‐S process, we can infer the correct skewed direction and magnitude of inactivation, which can elucidate significant findings regarding the genetic mechanism. A population‐level model and a more general subject‐level model have been developed to model the XCI‐S process. Finite sample performance of this novel method is examined via extensive simulation studies. An application is illustrated with implementation of the method on a cancer genetic study with survival outcome.
Phagocytic clearance of presynaptic dystrophies by reactive astrocytes in Alzheimer's disease
Authors: Gomez‐Arboledas Angela , Davila Jose C. , Sanchez‐Mejias Elisabeth , Navarro Victoria , Nuñez‐Diaz Cristina , Sanchez‐Varo Raquel , Sanchez‐Mico Maria Virtudes , Trujillo‐Estrada Laura , Fernandez‐Valenzuela Juan Jose , Vizuete Marisa , Comella Joan X. , Galea Elena , Vitorica Javier , Gutierrez Antonia
Published: November 2017

Reactive astrogliosis, a complex process characterized by cell hypertrophy and upregulation of components of intermediate filaments, is a common feature in brains of Alzheimer's patients. Reactive astrocytes are found in close association with neuritic plaques; however, the precise role of these glial cells in disease pathogenesis is unknown. In this study, using immunohistochemical techniques and light and electron microscopy, we report that plaque‐associated reactive astrocytes enwrap, engulf and may digest presynaptic dystrophies in the hippocampus of amyloid precursor protein/presenilin‐1 (APP/PS1) mice. Microglia, the brain phagocytic population, was apparently not engaged in this clearance. Phagocytic reactive astrocytes were present in 35% and 67% of amyloid plaques at 6 and 12 months of age, respectively. The proportion of engulfed dystrophic neurites was low, around 7% of total dystrophies around plaques at both ages. This fact, along with the accumulation of dystrophic neurites during disease course, suggests that the efficiency of the astrocyte phagocytic process might be limited or impaired. Reactive astrocytes surrounding and engulfing dystrophic neurites were also detected in the hippocampus of Alzheimer's patients by confocal and ultrastructural analysis. We posit that the phagocytic activity of reactive astrocytes might contribute to clear dysfunctional synapses or synaptic debris, thereby restoring impaired neural circuits and reducing the inflammatory impact of damaged neuronal parts and/or limiting the amyloid pathology. Therefore, potentiation of the phagocytic properties of reactive astrocytes may represent a potential therapy in Alzheimer's disease.
Advanced service offshore outsourcing: Exploring the determinants of capability development in emerging market firms
Authors: Brandl Kristin , Jensen Peter D. Ørberg , Lind Manya Jaura
Published: November 2017

Research Summary: We analyze the effect of offshored service task types on the development of capabilities in emerging market service provider firms. Using multiple case studies, we find that, dependent on task interdependent service types, implying different client interactions (firm‐external determinants), organizational capabilities are developed. More specifically, reciprocal task interdependent services generate human capital and management capabilities, while sequential task interdependent services generate organizational capital and management capabilities. Moreover, we find a relationship between the capabilities, where the deficient development of one capability can be mitigated by the development of another capability (firm‐internal determinants). Grounded in organization and service production theory, the article contributes to the thematic literature on service offshoring and the literature on organizational capabilities, with a particular focus on emerging market firms.

Managerial Summary: Offshore outsourcing of advanced services is contributing to the development of capabilities for client firms, but is also expected to benefit service provider firms from emerging markets. Thus, we study how offshore outsourcing of services contributes to the development of these capabilities for service provider firms. We find that the characteristics of the services, which are causing different interactions with the client, help the firm develop a variety of capabilities. These capabilities affect the management, employees, and organization of service provider firms. Although the developed competencies are not a solution for all business development challenges of emerging market firms, the implications of this study could lead to competitive advantages for the firms if fully explored and exploited.
Angiotensin‐1‐converting enzyme inhibition, antioxidant activity, and modulation of cerebral Na+/K+ ATPase by free phenolics of African locust bean (Parkia biglobosa)
Authors: Komolafe Kayode , Akinmoladun Afolabi C. , Komolafe Titilope R. , Olaleye Mary T. , Boligon Aline A. , Akindahunsi Akintunde A. , Rocha Joao B.T.
Published: November 2017

Aims

To investigate the antioxidant activities and effects of free phenols (FPPB) and bound phenols (BPPB) of Parkia biglobosa leaves on some enzymes of neuro‐cardiovascular relevance.

Methods and Results

HPLC‐DAD fingerprinting of FPPB and BPPB, and the antihemolytic, radical (1,1‐diphenyl‐2 picrylhydrazyl, DPPH; 2,2‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulphonic acid), ABTS) scavenging and ferric reducing antioxidant properties of extracts, were assessed. In addition, the effects of the phenolics on angiotensin‐1‐converting enzyme (ACE), cerebral acetylcholinesterase/butyrylcholinesterase (AChE/BuChE), and Na+/K+ATPase were determined in vitro. FPPB was more potent than BPPB in terms of ABTS (EC50:4.06 ± 0.3 vs 24.07 ± 2.1 μg/mL) and DPPH (EC50:3.82 ± 0.2 vs 10.22 ± 0.1 μg/mL) radicals scavenged, respectively. The free phenolic extract was a better DPPH. scavenger than ascorbic acid (EC50 = 12.58 ± 0.4 μg/mL; DPPH reference) and compared well with Trolox (EC50:4.44 ± 0.08 μg/mL; ABTS reference). The anti‐hemolytic effect of FPPB (36%) and BPPB (53%) was highest at 15 μg/mL but lower than that recorded for ascorbic acid (67% at 10 μg/mL). Even though FPPB (IC50 = 15.35 ± 4.0 μg/mL) and BPPB (IC50 = 46.85 ± 3.3 μg/mL) showed considerably lower ACE‐inhibitory effect than ramipril (IC50:0.173 ± 0.04 μg/mL), both extracts demonstrated dose‐dependent, significant (p < 0.01/p < 0.05) inhibition of the enzyme. FPPB increased cerebral Na+/K+ATPase activity but neither phenolic extract affects cerebral AChE/BuChE activities. HPLC‐DAD revealed catechin, caffeic acid, and quercetin, respectively, as the major phenolics (mg/g) in FPPB (29.85, 30.29, and 17.10) and BPPB (32.70, 30.51, and 19.25).

Conclusion

The effects of P biglobosa on ACE and cerebral ATPase are related to its constituent phenolics. ACE inhibition could be an important mechanism underlying the documented hypotensive effect of the plant.
DFT Study of the Strong Solvent Effects in the Cu‐Catalyzed Asymmetric Conjugate Addition Reaction
Authors: Ling Zheng , Xie Fang , Gridnev Ilya D. , Zhang Wanbin
Published: November 2017

Significant solvent effects on enantioselection exist in the reaction of Cu‐catalyzed asymmetric conjugate addition of alkylzinc reagents to α,β‐unsaturated carbonyl compounds. Results of our DFT study suggest that solvent effects on enantioselection can be caused by structural changes in the stereodetermining Transition States (TS). We have seen how unconventional hydrogen bonding of the nucleophilic solvent results in a change of the computed optical yield comparable to that caused by well‐known coordination of the solvent to the electrophilic metal center.
Rhodium‐catalyzed Asymmetric Arylation of Nitroalkenes Powered by Simple Chiral Sulfur‐Olefin Ligands
Authors: Wang Zheng , Chen Wen‐Wen , Xu Ming‐Hua
Published: November 2017

An efficient rhodium‐catalyzed enantioselective addition of potassium organotrifluoroborates to nitroalkenes powered by simple chiral sulfur‐olefin ligands is reported. This protocol is applicable to a broad range of 2‐aryl‐, alkyl‐, and heteroaryl‐substituted nitroalkenes, allowing access to diverse chiral β,β‐disubstituted nitroethanes in good to excellent yields with high enantioselectivity under mild conditions.
Microvascular characteristics of the acoustic fats: Novel data suggesting taxonomic differences between deep and shallow‐diving odontocetes
Authors: Gabler Molly K. , Gay D. Mark , Westgate Andrew J. , Koopman Heather N.
Published: November 2017

Odontocetes have specialized mandibular fats, the extramandibular (EMFB) and intramandibular fat bodies (IMFB), which function as acoustic organs, receiving and channeling sound to the ear during hearing and echolocation. Recent strandings of beaked whales suggest that these fat bodies are susceptible to nitrogen (N2) gas embolism and empirical evidence has shown that the N2 solubility of these fat bodies is higher than that of blubber. Since N2 gas will diffuse from blood into tissue at any blood/tissue interface and potentially form gas bubbles upon decompression, it is imperative to understand the extent of microvascularity in these specialized acoustic fats so that risk of embolism formation when diving can be estimated. Microvascular density was determined in the EMFB, IMFB, and blubber from 11 species representing three odontocete families. In all cases, the acoustic tissues had less (typically 1/3 to 1/2) microvasculature than did blubber, suggesting that capillary density in the acoustic tissues may be more constrained than in the blubber. However, even within these constraints there were clear phylogenetic differences. Ziphiid (Mesoplodon and Ziphius, 0.9 ± 0.4% and 0.7 ± 0.3% for EMFB and IMFB, respectively) and Kogiid families (1.2 ± 0.2% and 1.0 ± 0.01% for EMFB and IMFB, respectively) had significantly lower mean microvascular densities in the acoustic fats compared to the Delphinid species (Tursiops, Grampus, Stenella, and Globicephala, 1.3 ± 0.3% and 1.3 ± 0.3% for EMFB and IMFB, respectively). Overall, deep‐diving beaked whales had less microvascularity in both mandibular fats and blubber compared to the shallow‐diving Delphinids, which might suggest that there are differences in the N2 dynamics associated with diving regime, phylogeny, and tissue type. These novel data should be incorporated into diving physiology models to further understand potential functional disruption of the acoustic tissues due to changes in normal diving behavior.
Global transition of human serum albumin to prefibrillar aggregates induced by temsirolimus: Insight into implications of anti‐renal cancer drug
Authors: Shamsi Anas , Ahmed Azaj , Bano Bilqees
Published: November 2017

In our study, we have characterized the prefibrillar aggregates of human serum albumin (HSA) induced by temsirolimus, anti‐renal cancer drug. Molecular docking was retorted to confirm binding of HSA and temsirolimus. Temsirolimus caused the structural transition of native HSA to non‐native species after prolonged incubation of 20 days. These non‐native species were characterized as prefibrillar aggregates as evident by decreased intrinsic fluorescence and enhanced 8‐anilino‐1‐naphthalene‐sulphonic acid (ANS) fluorescence. Further, enhanced thioflavin T fluorescence and shift in congo red (CR) spectra of temsirolimus‐incubated HSA as compared to native HSA are suggestive of global transition of HSA in presence of temsirolimus towards prefibrillar aggregates. Circular dichroism spectroscopy revealed α to β transition upon prolonged incubation with temsirolimus suggesting the formation of prefibrillar aggregates as aggregates are known to possess high β content. Scanning electron microscopy confirmed these non‐native species to be prefibrillar aggregates evident by observed sheath‐like structures. Comet assay was retorted to confirm genotoxic nature of these prefibrillar aggregates; DNA damage was observed for temsirolimus‐incubated HSA confirming the genotoxic nature of prefibrillar aggregates. These prefibrillar aggregates are observed at heart of many pathological conditions, thus making our study clinically significant.
Developing and validating a multivariable prediction model to improve the diagnostic accuracy in determination of cervical versus endometrial origin of uterine adenocarcinomas: A prospective MR study combining diffusion‐weighted imaging and spectroscopy
Authors: Lin Gigin , Lin Yu‐Chun , Wu Ren‐Chin , Yang Lan‐Yan , Lu Hsin‐Ying , Tsai Shang‐Yueh , Huang Yu‐Ting , Huang Yen‐Ling , Lu Kuan‐Ying , Ng Koon‐Kwan , Yen Tzu‐Chen , Chao Angel , Lai Chyong‐Huey , Hong Ji‐Hong
Published: November 2017

Background

A triage test to assist clinical decision‐making on choosing primary chemoradiation for cervical carcinomas or primary surgery for endometrial carcinomas is important.

Purpose or Hypothesis

To develop and validate a multiparametric prediction model based on MR imaging and spectroscopy in distinguishing adenocarcinomas of uterine cervical or endometrial origin.

Study Type

Prospective diagnostic accuracy study.

Population

Eighty‐seven women: 25 cervical and 62 endometrial adenocarcinomas divided into training (n = 43; cervical/endometrial adenocarcinomas = 11/32) and validation (n = 44; 14/30) datasets.

Field Strength/Sequence

The 3T diffusion‐weighted (DW) MR imaging and MR spectroscopy.

Assessment

Morphology, volumetric DW MR imaging and spectroscopy (MDS) scoring system with total points 0–5, based on presence of the following MR features assessed independently by two radiologists: (a) epicenter at the cervix, (b) rim enhancement, (c) disrupted cervical stromal integrity, (d) mean volumetric apparent diffusion coefficient values (ADCmean) higher than 0.98 × 10‐3 mm2/s, (e) fatty acyl δ 1.3 ppm more than 161.92 mM. Histopathology as gold standard.

Statistical Tests

Logistic regression and receiver operator characteristic (ROC) curves analysis.

Results

For both the training and validation datasets, the MDS score achieved an accuracy of 93.0% and 84.1%, significantly higher than that of morphology (88.4% and 79.5%), ADC value (74.4% and 68.2%), and spectroscopy (81.4% and 68.2%; P < 0.05 for all). The performances of the scoring were superior to the morphology in the training dataset (areas under the receiver operating characteristics curve [AUC] = 0.95 vs. 0.89; P = 0.046), but not in the validation dataset (AUC = 0.90 vs. 0.85; P = 0.289).

Data Conclusion

MDS score has potentials to improve distinguishing adenocarcinomas of cervical or endometrial origin, and warrants large‐scale studies for further validation.

Level of Evidence: 1

Technical Efficacy: Stage 3

J. Magn. Reson. Imaging 2018;47:1654–1666.
Need for recovery after emotional labor: Differential effects of daily deep and surface acting
Authors: Xanthopoulou Despoina , Bakker Arnold B. , Oerlemans Wido G.M. , Koszucka Maria
Published: November 2017

This diary study examines the psychological processes that contribute to daily recovery from emotional labor by combining emotion regulation with work‐home resources theories. We hypothesized that overall perceptions of display rules relate positively to daily deep and surface acting. Daily surface acting was expected to relate positively to exhaustion and negatively to flow during work and consequently, to a higher need for recovery at the end of the workday. In contrast, daily deep acting was hypothesized to relate positively to flow and negatively to exhaustion and consequently, to a lower need for recovery at the end of the workday. In turn, need for recovery was expected to associate negatively to vigor at bedtime through reduced relaxation during leisure. Fifty Dutch and Polish employees first filled in a survey, and then a diary for five consecutive workdays, twice per day: at the end of the workday and before sleep. Multilevel path analyses largely supported these hypotheses suggesting that surface acting has unfavorable implications, whereas deep acting has favorable implications for daily well‐being at work and recovery after work.
Step by step: Capturing the dynamics of work team process through relational event sequences
Authors: Schecter Aaron , Pilny Andrew , Leung Alice , Poole Marshall Scott , Contractor Noshir
Published: November 2017

The emergence of group constructs is an unfolding process, whereby actions and interactions coalesce into collective psychological states. Implicitly, there is a connection between these states and the underlying procession of events. The manner in which interactions follow one another over time describe a group's behavior, with different temporal patterns being indicative of different team characteristics. In this study, we explicitly connect event sequences to the process of emergence. We argue that the temporal relationship between events in a sequence will vary depending on the team's psychological outcome. Further, certain patterns of behavior will be repeated at different rates in teams with varying emergent states. To support this approach, we apply a statistical methodology—relational event modeling—for analyzing sequences of interactions that builds on the foundation of social network analysis. Using a dataset comprised of 55 work teams of military personnel engaged in a tactical scenario, we found that individuals who perceived team process (regarding coordination and information sharing) as having different qualities engaged in significantly different patterns of behavior. Our findings indicate that individuals who had a positive perception of process quality were more likely to initiate communication events in a reciprocal, transitive, and decentralized fashion.
Why is your boss making you sick? A longitudinal investigation modeling time‐lagged relations between abusive supervision and employee physical health
Authors: Liang Lindie H. , Hanig Samuel , Evans Rochelle , Brown Douglas J. , Lian Huiwen
Published: November 2017

Although an abundance of cross‐sectional data have linked abusive supervision with employees' experience of health‐related problems, further research accounting for the temporal dynamics of these variables is needed to establish causality. Furthermore, the process by which abusive supervision relates to subordinate health problems requires greater clarification. In a 1‐year longitudinal cross‐lagged investigation, we sought to test the time‐lagged relationship between abusive supervision and employee physical health; additionally, we test rumination as a cognitive process that mediates this time‐lagged relationship while modeling other relevant social and motivational mediators. Our results indicate that subordinate ruminative thinking about their experiences of abusive supervision mediates the time‐lagged association between abusive supervision and physical health problems. These findings suggest that reducing ruminative thinking may limit the long‐term impact of abusive supervision on employees' physical health.
Role of dexamethasone in the long‐term functional maturation of MSC‐laden hyaluronic acid hydrogels for cartilage tissue engineering
Authors: Kim Minwook , Garrity Sean T. , Steinberg David R. , Dodge George R. , Mauck Robert L.
Published: November 2017

The purpose of study was to investigate the maturation of mesenchymal stem cells (MSC) laden in HA constructs with various combinations of chemically defined medium (CM) components and determine the impact of dexamethasone and serum on construct properties. Constructs were cultured in CM with the addition or withdrawal of media components or were transferred to serum containing media that partially represents an in vivo‐like condition where pro‐inflammatory signals are present. Constructs cultured in CM+ (CM with TGF‐β3) and DEX− (CM+ without dexamethasone) conditions produced robust matrix, while those in ITS/BSA/LA− (CM+ without ITS/BSA/LA) and Serum+ (10% FBS with TGF‐β3) produced little matrix. While construct properties in DEX− were greater than those in CM+ at 4 weeks, properties in CM+ and DEX− reversed by 8 weeks. While construct properties in DEX− were greater than those in CM+ at 4 weeks, the continued absence or removal of dexamethasone resulted in marked GAG loss by 8 weeks. Conversely, the continued presence or new addition of dexamethasone at 4 weeks further improved or maintained construct properties through 8 weeks. Finally, when constructs were converted to Serum (in the continued presence of TGF‐β3 with or without dexamethasone) after pre‐culture in CM+ for 4 weeks, GAG loss was attenuated with addition of dexamethasone. Interestingly, however, collagen content and type was not impacted. In conclusion, dexamethasone influences the functional maturation of MSC‐laden HA constructs, and may help to maintain properties during long‐term culture or with in vivo translation by repressing pro‐inflammatory signals. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1717–1727, 2018.
Frontal plane hip joint loading according to pain severity in people with hip osteoarthritis
Authors: Hall Michelle , Allison Kim , Wrigley Tim V. , Metcalf Ben R. , Pua Yong‐Hao , Van Ginckel Ans , Bennell Kim L.
Published: November 2017

The primary objective was to examine the hip adduction moment during walking in people with hip osteoarthritis (OA) according to pain severity. Sixty‐eight participants with unilateral symptomatic hip OA were included. Pain during walking was assessed on a 5‐point Likert item within the Western Ontario and McMaster Universities Index (no pain = 12; mild pain n = 37; moderate pain n = 19). Measures of the external hip adduction moment (peaks, Nm/BW × BH (%) and impulse, Nm.s/BW × BH (%)) were determined. Other measures included frontal plane hip, pelvis and trunk kinematics, walking speed and peak isometric hip abductor strength. Variables were compared according to pain severity using linear models and biomechanical variables were examined. Participants with moderate pain had a significantly higher second peak hip adduction moment and impulse compared to those with less pain. There was no difference in any measure of hip adduction moment between those with mild pain and no pain. There were no differences in kinematics across pain severity categories. Participants with moderate pain had a significantly slower walking speed compared to participants with mild and no pain. Participants with moderate pain had weaker peak isometric hip abductor strength compared to those with mild pain and no pain. The hip adduction moment during walking, hip abduction strength and walking speed differs according to pain severity during walking in people with hip OA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1637–1644, 2018.
Authentication of commercial spices based on the similarities between gas chromatographic fingerprints
Authors: Matsushita Takaya , Zhao Jing Jing , Igura Noriyuki , Shimoda Mitsuya
Published: November 2017

BACKGROUND

A simple and solvent‐free method was developed for the authentication of commercial spices. The similarities between gas chromatographic fingerprints were measured using similarity indices and multivariate data analyses, as morphological differentiation between dried powders and small spice particles was challenging. The volatile compounds present in 11 spices (i.e. allspice, anise, black pepper, caraway, clove, coriander, cumin, dill, fennel, star anise, and white pepper) were extracted by headspace solid‐phase microextraction, and analysed by gas chromatography–mass spectrometry.

RESULTS

The largest 10 peaks were selected from each total ion chromatogram, and a total of 65 volatiles were tentatively identified. The similarity indices (i.e. the congruence coefficients) were calculated using the data matrices of the identified compound relative peak areas to differentiate between two sets of fingerprints. Where pairs of similar fingerprints produced high congruence coefficients (>0.80), distinctive volatile markers were employed to distinguish between these samples. In addition, hierarchical cluster analysis and principal component analysis were performed to visualise the similarity among fingerprints, and the analysed spices were grouped and characterised according to their distinctive major components.

CONCLUSION

This method is suitable for screening unknown spices, and can therefore be employed to evaluate the quality and authenticity of various spices. © 2017 Society of Chemical Industry
l‐Cysteine‐modified silver‐functionalized silica‐based material as an efficient solid‐phase extraction adsorbent for the determination of bisphenol A
Authors: Li Yuanyuan , Zhu Nan , Li Bingxiang , Chen Tong , Ma Yulong , Li Qiang
Published: November 2017

A new silver‐functionalized silica‐based material with a core–shell structure based on silver nanoparticle‐coated silica spheres was synthesized, and silver nanoparticles were modified using strongly bound l‐cysteine. l‐Cysteine‐silver@silica was characterized by scanning electron microscopy and FTIR spectroscopy. Then, a solid‐phase extraction method based on l‐cysteine‐silver@silica was developed and successfully used for bisphenol A determination prior to HPLC analysis. The results showed that the l‐cysteine‐silver@silica as an adsorbent exhibited good enrichment capability for bisphenol A, and the maximum adsorption saturation was 20.93 mg/g. Moreover, a short adsorption equilibrium time was obtained due to the presence of silver nanoparticles on the surface of the silica. The extraction efficiencies were then optimized by varying the eluents and pH. Under the optimized conditions, good linearity for bisphenol A was obtained in the range from 0.4 to 4.0 μM (R2 > 0.99) with a low limit of detection (1.15 ng/mL). The spiked recoveries from tap water and milk samples were satisfactory (85–102%) with relative standard deviations below 5.2% (n = 3), which indicated that the method was suitable for the analysis of bisphenol A in complex samples.
Simultaneous quantitative assessment of nine glycosides in tobacco by liquid chromatography–tandem mass spectrometry
Authors: Yuan Yue , Zhou Rong , Li Dongliang , Luo Cheng , Li Guoyou
Published: November 2017

A simple and efficient method combining ultrasound‐assisted extraction, the conditions of which were optimized by response surface methodology, with liquid chromatography and tandem mass spectrometry was established and validated for the absolute quantification of nine non‐volatile neutral glycosides originating from tobacco (Nicotiana tobaccum L.) leaves, comprising three phenolic glycosides, one benzanoid glycoside, and five sesquiterpene glycosides within three isomers, originating from tobacco leaves. Factors of extraction time, sample quantity, extraction solvent, liquid chromatographic conditions, and electrospray ionization parameters were carefully investigated to ensure the selectivity and sensitivity of the method. All calibration curves showed excellent coefficients of determination ranging from 0.9940 to 0.9996, within the range of tested concentrations. The limits of detection and quantification were 2.33–25.9 and 7.06–78.5 ng/mL, respectively. Satisfactory values of accuracy were between 80.1 to 107.9% among different sample matrixes. The relative standard deviations of intra‐ and inter‐day analysis were less than 13.7 and 13.0% respectively. The developed method was successfully applied in a pilot study to determine the amounts of the nine endogenous glycosides in real flue‐cured tobacco samples obtained from different habitats in China.
Analysis of emerging organic contaminants in poultry manure by gas chromatography–tandem mass spectrometry
Authors: Aznar Ramón , Albero Beatriz , Pérez Rosa Ana , Sánchez‐Brunete Consuelo , Miguel Esther , Tadeo José L.
Published: November 2017

A multiresidue method was developed for the determination of 19 emerging organic contaminants (pharmaceutical drugs, personal care products, and bisphenol A) in poultry manure. Lyophilized samples of manure were extracted by ultrasound‐assisted matrix solid‐phase dispersion and the extracts were analyzed by gas chromatography with tandem mass spectrometry after derivatization. Analysis of spiked poultry manure samples, at levels ranging from 25 to 150 ng/g, gave satisfactory recovery results for all the compounds, with values from 67 to 106%. The developed procedure provided detection limits that ranged from 0.9 to 2.2 ng/g. Finally, the validated method was applied to poultry manure samples collected from 23 poultry farms in Spain. Salicylic acid was found in most of the samples analyzed at levels up to 2501 ng/g, whereas, methyl paraben, orthophenylphenol, ibuprofen, paracetamol, and carbamazepine were detected at levels up to 250 ng/g. Composting of manure showed an important decrease in the levels of the detected contaminants.
Geographic impact evaluation of the quality of Alismatis Rhizoma by untargeted metabolomics and quantitative assay
Authors: Wu Jia , Yang Wenzhi , Pan Huiqin , Yao Shuai , Wu Wanying , Guo Dean
Published: November 2017

The geographic impact on the quality of Alismatis Rhizoma (derived from the tuber of Alisma orientale), a reputable diuretic traditional Chinese medicine, has seldom been evaluated. Here a metabolomics‐driven approach targeting the bioactive protostane triterpenes was developed, by incorporating UHPLC with quadrupole time‐of‐flight mass spectrometry‐based untargeted metabolite profiling and multiple reaction monitoring quantitative assay, to probe the triterpene differences between Alismatis Rhizoma samples collected from Sichuan, Fujian, and Jiangxi Provinces. Following the metabolomics workflows, the samples from Sichuan and Jiangxi displayed distinct differences in their triterpene profiles, whereas those from Fujian showed remarkable intra‐class variation. Twenty‐three triterpenes were identified to contribute most to the differentiated clustering. A sensitive, precise, repeatable, and accurate quantitative assay method was established on a hybrid triple quadrupole‐linear ion trap mass spectrometer to quantify the contents of eight triterpene compounds. Taking into account the metabolomics and quantitation results, alisol B 23‐acetate and alisol A are significantly different in Alismatis Rhizoma from Sichuan and Jiangxi Provinces, and they may have the potential for geographic discrimination. These results illustrate how geographic difference impacts the triterpene chemistry of Alismatis Rhizoma. Metabolomics‐driven chemical comparison is suitable for the quality evaluation of traditional Chinese medicine.
Selective extraction of morphine from biological fluids by magnetic molecularly imprinted polymers and determination using UHPLC with diode array detection
Authors: Ebrahimi Rahmani Mahdiyeh , Ansari Mehdi , Kazemipour Maryam , Nateghi Mohammadreza
Published: November 2017

The determination of morphine concentration in the blood and urine is necessary for patients and recruitment purposes. Herein, a magnetic molecularly imprinted polymer for selective and efficient extraction of morphine from biological samples was synthesized by using a core–shell method. Fe3O4 nanoparticles were coated with SiO2‐NH2. The molecularly imprinted polymer was coated on the Fe3O4/SiO2‐NH2 surface by the copolymerization of methacrylic acid and ethylene glycol dimethacrylate in the presence of morphine as the template molecule. The morphological and magnetic properties of the polymer were investigated. Field‐emission scanning electron microscopy indicated that the prepared magnetic polymer is almost uniform. The saturation magnetization values of Fe3O4 nanoparticles, Fe3O4/SiO2‐NH2, and the magnetic polymer were 48.41, 31.69, and 13.02 emu/g, respectively, indicating that all the particles are superparamagnetic. Kinetics of the adsorption of morphine on magnetic polymer were well described by second‐order kinetic and adsorption processes and well fitted by the Langmuir adsorption isotherm, in which the maximum adsorption capacity was calculated as 28.40 mg/g. The recoveries from plasma and urine samples were in the range of 84.9–105.5 and 94.9–102.8%, respectively. By using the magnetic molecularly imprinted polymer, morphine can selectively, reliably, and in low concentration be determined in biological samples with high‐performance liquid chromatography and UV detection.
Synthesis and chromatographic evaluation of phenyl/tetrazole bonded stationary phase based on thiol‐epoxy ring opening reaction
Authors: Jin Gaowa , Liu Yanming , Yang Fan , Yu Dongping , Yan Jingyu , Zhou Weijia , Guo Zhimou , Zhu Jianhua , Liang Xinmiao
Published: November 2017

A silica‐based reversed‐phase stationary phase bonding with phenyl and tetrazole groups was synthesized by thiol‐epoxy ring opening reaction. The bonded groups could not only provide hydrophobic interaction, but also π–π, hydrogen bonding, electrostatic interactions, and so on. The results of characterization with elemental analysis and solid‐state 13C cross‐polarization magic‐angle‐spinning NMR spectroscopy indicated the successful preparation of phenyl/tetrazole sulfoether bonded stationary phase. Chromatographic evaluation revealed that phenyl/tetrazole sulfoether bonded stationary phase behaved well under the reversed‐phase mode. The column parameters (H, S*, A, B, and C) showed different selectivity compared with some typical commercial columns, and it was validated by the separation of estrogen, ginsenoside, alkaloid samples. Based on the different selectivity between phenyl/tetrazole sulfoether bonded stationary phase and C18 columns, phenyl/tetrazole sulfoether bonded stationary phase also showed potential to construct a 2D reversed‐phase liquid chromatography system with C18. And it was verified by the separation of corydalis tuber and curcuma zedoary extracts.
Generic approach to the method development of intact protein separations using hydrophobic interaction chromatography
Authors: Tyteca Eva , De Vos Jelle , Tassi Marco , Cook Ken , Liu Xiaodong , Kaal Erwin , Eeltink Sebastiaan
Published: November 2017

We describe a liquid chromatography method development approach for the separation of intact proteins using hydrophobic interaction chromatography. First, protein retention was determined as function of the salt concentration by isocratic measurements and modeled using linear regression. The error between measured and predicted retention factors was studied while varying gradient time (between 15 and 120 min) and gradient starting conditions, and ranged between 2 and 15%. To reduce the time needed to develop optimized gradient methods for hydrophobic interaction chromatography separations, retention‐time estimations were also assessed based on two gradient scouting runs, resulting in significantly improved retention‐time predictions (average error < 2.5%) when varying gradient time. When starting the scouting gradient at lower salt concentrations (stronger eluent), retention time prediction became inaccurate in contrast to predictions based on isocratic runs. Application of three scouting runs and a nonlinear model, incorporating the effects of gradient duration and mobile‐phase composition at the start of the gradient, provides accurate results (improved fitting compared to the linear solvent‐strength model) with an average error of 1.0% and maximum deviation of –8.3%. Finally, gradient scouting runs and retention‐time modeling have been applied for the optimization of a critical‐pair protein isoform separation encountered in a biotechnological sample.
High‐Temperature Rate Constants for H + Tetramethylsilane and H + Silane and Implications about Structure–Activity Relationships for Silanes
Authors: Peukert S. , Herzler J. , Fikri M. , Schulz C.
Published: November 2017

The shock‐tube technique has been used to investigate the reactions H + SiH4 → H2 + SiH3 (R1) and H + Si(CH3)4 → Si(CH3)3CH2 + H2 (R2) behind reflected shock waves. C2H5I was used as a thermal in situ source for H atoms. For reaction (R1), the experiments covered a temperature range of 1170–1251 K and for (R2) 1227–1320 K. In both cases, the pressures were near 1.5 bar. In these experiments, H atoms were monitored with atomic resonance absorption spectrometry. Fits to the H‐atom temporal concentration profiles applying postulated chemical kinetic reaction mechanisms were used for determining the rate constants k1 and k2. Experimental rate constants were well represented by the Arrhenius equations k1(T) = 2.75 × 10−9 exp(−37.78 kJ mol−1/RT) cm3 s−1 and k2(T) = 1.17 × 10−7 exp(−86.82 kJ mol−1/RT) cm3 s−1. Transition state theory (TST) calculations based on CBS‐QB3 and G4 levels of theory show good agreement with experimentally obtained rate constants; the experimental values for k1 and k2 are ∼40% lower and ∼50% larger than theoretical predictions, respectively. For the development of a mechanism describing the thermal decomposition of tetramethylsilane (Si(CH3)4; TMS), also TST‐based rate constants for reaction CH3 + Si(CH3)4 → Si(CH3)3CH2 + CH4 (R3) were calculated. A comparison between experimental and theoretical rate constants k2 and k3 with available rate constants from the literature indicates that Si(CH3)4 has very similar reactivity toward H abstractions like neopentane (C(CH3)4), which is the analog hydrocarbon to TMS. Based on these results, the possibility of drawing reactivity analogies between hydrocarbons and structurally similar silicon‐organic compounds for H‐atom abstractions is discussed.
Optimization of a high‐throughput phenotyping method for chain‐forming phytoplankton species
Authors: Gross Susanna , Kourtchenko Olga , Rajala Tuomas , Andersson Björn , Fernandez Luciano , Blomberg Anders , Godhe Anna
Published: November 2017

Modern equipment facilitates phenotyping of hundreds of strains of unicellular organisms by culturing and monitoring growth in microplates. However, in the field of phytoplankton ecology, automated monitoring of growth is not often done and this method has not been tested for many species. To meet the demand for a high‐throughput technique for monitoring growth of chain‐forming phytoplankton species, we have assessed and optimized a method commonly used for other microorganisms. Skeletonema marinoi is a pelagic chain‐forming diatom, and we have acquired growth patterns in four different treatments (i.e., low and high light, low and high nutrient concentrations) when cultured in multi‐well plates. Due to the unexpected heterogeneity in growth rates and maximum cell densities observed between wells (spatial) and runs (temporal), a set of models was fitted to the obtained phenotypic data to correct for these biases. Models were tested for robustness on two replicate multi‐strain experiments including 23 different strains. Using the model accounting for temporal and spatial bias, we could reliably determine changes in growth rate caused by nutrient treatments as well as differences in cell density as a response to nutrient availability and light treatment. This method can facilitate high‐throughput phenotyping of hundreds of strains, which is often a bottleneck in characterizing the ecology and capacity for adaptation of chain‐forming phytoplankton.