bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanistic and Kinetic Factors of ortho‐Benzyne Formation in Hexadehydro‐Diels‐Alder (HDDA) Reactions
Authors: Maier Jan , Marder Todd B.
Published: March 2021

With the rapid development of the hexadehydro‐Diels‐Alder reaction (HDDA) from its first discovery in 1997, the question of whether a concerted or stepwise mechanism better describes the thermally activated formation of ortho‐benzyne from a diyne and a diynophile has been debated. Mechanistic and kinetic investigations were able to show that this is not a black or white situation, as minor changes can tip the balance. For that reason, especially, linked yne‐diynes were studied to examine steric, electronic, and radical‐stabilizing effects of their terminal substituents on the reaction mechanism and kinetics. Furthermore, the influence of the nature of the linker on the HDDA reaction was explored. The more recently discovered photochemical HDDA reaction also gives ortho‐arynes, which display the same reactivity as the thermally generated ones, but their formation might not proceed by the same mechanism. This minireview summarizes the current state of mechanistic understanding of the HDDA reaction.
Unveiling the Hidden σ‐Dimerization of a Kinetically Protected Olympicenyl Radical
Authors: Xiang Qin , Xu Jun , Guo Jing , Dang Yanfeng , Xu Zhanqiang , Zeng Zebing , Sun Zhe
Published: March 2021

The σ‐dimer of a kinetically protected olympicenyl radical, which evaded the experimental detection, was revealed by conversion into biolympicenylidene with E‐configuration in a regioselective manner. The complicated stereochemistry and energetics of the σ‐dimers derived from C2v symmetry and uneven spin distribution of the olympicenyl radical were revealed by the theoretical calculations, and the energetic preference of π‐dimer over σ‐dimer by a minute gap was disclosed. The E‐biolympicenylidene, a polycyclic ene structure previously considered as reactive intermediate in the phenalenyl radical system, exhibited exceptional stability, which allowed for a detailed investigation on its singlet diradical character and physical properties by means of X‐ray crystallography, UV‐vis‐NIR absorption/emission spectroscopy and cyclic voltammetry, and assisted by theoretical calculations. The E‐biolympicenylidene showed high resistance towards both thermal and photochemical ring‐cyclization reactions, which was attributed to high activation energies for the rate‐determining electrocyclization operated on both disrotatory and conrotatory mode, as well as a small spin density at the bonding sites for the radical‐radical coupling process.
Total Syntheses and Chemical Biology Studies of Hymeglusin and Fusarilactone A, Novel Circumventors of β‐Lactam Drug Resistance in Methicillin‐Resistant Staphylococcus aureus
Authors: Kanaida Masahiro , Kimishima Aoi , Eguchi Shuhei , Iwatsuki Masato , Watanabe Yoshihiro , Honsho Masako , Hirose Tomoyasu , Noguchi Yoshihiko , Nonaka Kenichi , Sennari Goh , Matsui Hidehito , Kaito Chikara , Hanaki Hideaki , Asami Yukihiro , Sunazuka Toshiaki
Published: March 2021

Hymeglusin, a previously known eukaryotic hydroxymethylglutaryl‐CoA (HMG−CoA) synthase inhibitor, was identified as circumventing the β‐lactam drug resistance in methicillin‐resistant Staphylococcus aureus (MRSA). We describe the concise total syntheses of a series of natural products, which enabled determination of the absolute configuration of fusarilactone A and provided structure‐activity relationship information. Based on previous reports, we speculated that the target protein of this circumventing effect may be MRSA bacterial HMG−CoA synthase (mvaS). We found that this enzyme was dose‐dependently inhibited by hymeglusin. Furthermore, overexpression of the MRSA mvaS gene and site‐directed mutagenesis studies suggested its binding site and the mechanism of action.
Investigating the effect of mouth guard use on aerobic performance in amateur boxers
Authors: Ahmed Irfan , Kipps Courtney , Fine Peter
Published: March 2021

Objectives

To assess if wearing a mouth guard impacts maximal aerobic capacity in amateur boxers.

Materials and Methods

A prospective crossover cohort (pilot) study was conducted to assess maximal aerobic capacity in amateur boxers using the 20 m multi stage fitness test (MSFT). Two primary outcomes measures were recorded: (1) the maximum oxygen uptake (peak VO2—mL/kg/min) and (2) distance run (meters—m). Thirteen amateur boxers completed the MSFT 7 days apart under control (no mouth guard—C) and intervention conditions (mouth guard—MG). Participants also submitted data on height, weight, type of mouth guard and Rate of Perceived Exertion (RPE) during the test.

Statistics

Paired T‐test.

Results

Mouth guard use was shown to reduce peak VO2 and distance run during the 20 m MSFT from 56.31 to 54.12 mL/kg/min and 2572 to 2380 m respectively (p < 0.05). Twelve out of 13 participants wore a Boil & Bite mouthguard and recorded lower peak VO2 scores (−4.38%) when wearing a mouth guard compared to control conditions, (Mean = −2.46 mL/kg/min, Range of decrease = 4.2–0.9 mL/kg/min; p < 0.05). Ten participants submitted data on RPE—One participant with a custom made mouthguard reported no change in RPE in mouthguard conditions, while nine participants reported an average (+30.5%) increase in mean RPE in Boil & Bite mouthguard conditions compared to control conditions.

Conclusions

Boil & Bite mouth guard use was shown to significantly reduce aerobic performance in amateur boxers and increase the perceived rate of exertion during the 20 m MSFT.
NLRP3 inflammasome of renal tubular epithelial cells induces kidney injury in acute hemolytic transfusion reactions
Authors: Liu Zhixin , Chen Yaozhen , Niu Bing , Yin Dandan , Feng Fan , Gu Shunli , An Qunxing , Xu Jinmei , An Ning , Zhang Jing , Yi Jing , Yin Wen , Qin Xiangyang , Hu Xingbin
Published: March 2021

Background

Blood transfusion, a common basic supporting therapy, can lead to acute hemolytic transfusion reaction (AHTR). AHTR poses a great risk to patients through kidney function damage in a short time. Previous reports found that heme from destroyed red blood cells impaired kidney function, and NLR family pyrin domain containing 3 (NLRP3) inflammasome was augmented in case of kidney injury. However, the detailed mechanism regarding whether NLRP3 inflammasome is involved in kidney function injury in AHTR is not fully understood yet.

Methods

Hemolysis models were established by vein injection with human blood plasma or mouse heme from destroyed red blood cells. The injured renal tubular epithelial cells (RTECs) were evaluated by tubular damage markers staining in hemolysis models and in primary RTECs in vitro. The activation of NLRP3 inflammasome in RTECs by hemes was investigated by Western blot, ELISA, scanning electron microscopy, immunofluorescent staining, flow cytometry, and hemolysis models. NLRP3 gene knockout mice were employed to confirm these observations in vitro and in vivo. The binding between a novel inhibitor (66PR) and NLRP3 was affirmed by molecule docking and co‐immunoprecipitation. The rescue of 66PR on kidney function impairment was explored in murine hemolysis models.

Results

We found that heme could activate NLRP3 inflammasome in RTECs to induce kidney function injury. NLRP3 gene knockout could prevent the damage of RTECs caused by hemes and recover kidney function in AHTR. Moreover, NLRP3 inflammasome chemical inhibitor, 66PR, could bind to NLRP3 protein and inhibit inflammasome activation in RTECs, which consequently relieved the injury of RTECs caused by hemes, and alleviated kidney function damage in the AHTR model.

Conclusions

Hemes could activate NLRP3 inflammasome in RTECs, and a novel NLRP3 inflammasome inhibitor named 66PR relieved kidney function damage in AHTR. Our findings provided a new possible strategy to treat kidney function failure in AHTR.
Positive long‐term impacts of restoration on soils in an experimental urban forest
Authors: Ward Elisabeth B. , Doroski Danica A. , Felson Alexander J. , Hallett Richard A. , Oldfield Emily E. , Kuebbing Sara E. , Bradford Mark A.
Published: March 2021

As urbanization increases worldwide, investments in nature‐based solutions that aim to mitigate urban stressors and counter the impacts of global climate change are also on the rise. Tree planting on degraded urban lands—or afforestation—is one form of nature‐based solution that has been increasingly implemented in cities around the world. The benefits of afforestation are, however, contingent on the capacity of soils to support the growth of planted trees, which poses a challenge in some urban settings where unfavorable soil conditions limit tree performance. Soil‐focused site treatments could help urban areas overcome impediments to afforestation, yet few studies have examined the long‐term (>5 yr) effects of site treatments on soils and other management objectives. We analyzed the impacts of compost amendments, interplanting with shrubs, and tree species composition (six species vs. two species) on soil conditions and associated tree growth in 54 experimental afforestation plots in New York City, USA. We compared baseline soil conditions to conditions after 6 yr and examined changes in the treatment effects from 1 to 6 yr. Site treatments and tree planting increased soil microbial biomass, water holding capacity, and total carbon and nitrogen, and reduced soil pH and bulk density relative to baseline conditions. These changes were most pronounced in compost‐amended plots, and the effects of the shrub and species composition treatments were minimal. In fact, compost was key to sustaining long‐term changes in soil carbon stocks, which increased by 17% in compost‐amended plots but declined in unamended plots. Plots amended with compost also had 59% more nitrogen than unamended plots, which was associated with a 20% increase in the basal area of planted trees. Improvements in soil conditions after 6 yr departed from the initial trends observed after 1 yr, highlighting the importance of longer‐term studies to quantify restoration success. Altogether, our results show that site treatments and tree planting can have long‐lasting impacts on soil conditions and that these changes can support multiple urban land management objectives.
Movement can mediate temporal mismatches between resource availability and biological events in host–pathogen interactions
Authors: Kürschner Tobias , Scherer Cédric , Radchuk Viktoriia , Blaum Niels , Kramer‐Schadt Stephanie
Published: March 2021

Global change is shifting the timing of biological events, leading to temporal mismatches between biological events and resource availability. These temporal mismatches can threaten species’ populations. Importantly, temporal mismatches not only exert strong pressures on the population dynamics of the focal species, but can also lead to substantial changes in pairwise species interactions such as host–pathogen systems. We adapted an established individual‐based model of host–pathogen dynamics. The model describes a viral agent in a social host, while accounting for the host's explicit movement decisions. We aimed to investigate how temporal mismatches between seasonal resource availability and host life‐history events affect host–pathogen coexistence, that is, disease persistence. Seasonal resource fluctuations only increased coexistence probability when in synchrony with the hosts’ biological events. However, a temporal mismatch reduced host–pathogen coexistence, but only marginally. In tandem with an increasing temporal mismatch, our model showed a shift in the spatial distribution of infected hosts. It shifted from an even distribution under synchronous conditions toward the formation of disease hotspots, when host life history and resource availability mismatched completely. The spatial restriction of infected hosts to small hotspots in the landscape initially suggested a lower coexistence probability due to the critical loss of susceptible host individuals within those hotspots. However, the surrounding landscape facilitated demographic rescue through habitat‐dependent movement. Our work demonstrates that the negative effects of temporal mismatches between host resource availability and host life history on host–pathogen coexistence can be reduced through the formation of temporary disease hotspots and host movement decisions, with implications for disease management under disturbances and global change.
Green Synthesis of Nitrogen‐to‐Ammonia Fixation: Past, Present, and Future
Authors: Zheng Jianyun , Jiang Li , Lyu Yanhong , Jiang San Ping , Wang Shuangyin
Published: March 2021

The nitrogen (N2)‐to‐ammonia (NH3) fixation driven by renewable energy has an attractive prospect to relieve the global warming and reduce the consumption of fossil fuels. Ideally, photocatalytic, electrochemical, and photoelectrochemical approaches are developed as the next‐generation NH3 synthesis technologies to substitute the Haber–Bosch method. However, the NH3 yield rate of nitrogen reduction reaction (NRR) by green approaches is extremely low, resulting in the current dilemma of NRR and contamination issues. Thus, in this mini review, the past advances on the sustainable NRR are briefly summarized in the three aspects as follows: the selectivity and adjustment of various catalysts, the type of electrolyte/solvent system, and the investigation of reaction conditions. Subsequently, the recent critical activities in the area of sustainable NH3 synthesis are analyzed and discussed deeply, and a perspective for rational and healthy development of this area is provided positively.
Discrete Benzotriazole‐Copper(II) Complexes in Chelated and Non‐Chelated Coordination Modes: Structural Analysis and Catalytic Application in Click and A3 Coupling Reactions
Authors: Pandey Sharmila , Mandal Tanmoy
Published: March 2021

Two copper(II) complexes with benzotriazole‐based ligands having pyridyl and quinolinyl arms were synthesized in good yields and characterized fully via spectroscopic and crystallographic techniques. The crystal structures of the complexes revealed different coordination environments around copper(II) centers. The difference in structure was due to the steric effect of the ligands, which resulted in an octahedral and a square pyramidal geometry of the resulting complexes in the solid state. Both the air‐stable complexes were utilized as precatalysts in catalytic click reactions and A3 coupling.
Gel‐based fluorescent proteomic tools for investigating cell redox signaling. A mini‐review
Authors: Majewska Anna M. , Mostek Agnieszka
Published: March 2021

The specific chemical reactivity of thiol groups makes protein cysteines susceptible to reactions with reactive oxygen species (ROS) and reactive nitrogen species (RNS) resulting in the formation of various reversible and irreversible oxidative post‐translational modifications (oxPTMs). This review highlights a number of gel‐based redox proteomic approaches to detect protein oxPTMs, with particular emphasis on S‐nitrosylation, which we believe are currently one of the most accurate way to analyze changes in the redox status of proteins. The information collected in this review relates to the recent progress regarding methods for the enrichment and identification of redox‐modified proteins, with an emphasis on fluorescent gel proteomics. Gel‐based fluorescent proteomic strategies are low‐cost and easy‐to‐use tools for investigating the thiol proteome and can provide substantial information on redox signaling.
The Ethical Limits of Children's Participation in Clinical Research
Authors: Ross Lainie Friedman
Published: March 2021

This essay reflects on arguments by Paul Ramsey, inThe Patient as Person: Explorations in Medical Ethics(1970) and elsewhere, that continue to challenge policy‐makers and those doing clinical and translational research involving children. Ramsey argued that parents cannot morally authorize their child's participation in research unless the research is designed to benefit the child. He acknowledged that abiding by this position could have adverse impacts on improving child health, and he concluded, in a 1976Hastings Center Reportpiece, that researchers must “sin bravely.” Many philosophers and theologians, including Richard McCormick, have argued against Ramsey. The Ramsey‐McCormick debate played out in the bioethics literature and, by invitation, at the deliberations of the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research, which was tasked with developing an ethics framework and policies for human subjects protections. Although in its final recommendations, the commission sided with McCormick, the strict limitations on risks and harms to which a child can be exposed were clearly influenced by Ramsey.
What We're Not Talking about When We Talk about Addiction
Authors: Pickard Hanna
Published: March 2021

The landscape of addiction is dominated by two rival models: a moral model and a model that characterizes addiction as a neurobiological disease of compulsion. Against both, I offer a scientifically and clinically informed alternative. Addiction is a highly heterogenous condition that is ill‐characterized as involving compulsive use. On the whole, drug consumption in addiction remains goal directed: people take drugs because drugs have tremendous value. This view has potential implications for the claim that addiction is, in all cases, a brain disease. But more importantly, it has implications for clinical and policy interventions. To help someone overcome addiction, you need to understand and address why they persist in using drugs despite negative consequences. If they are not compelled, then the explanation must advert to the value of drugs for them as an individual. What blocks us from acknowledging this reality is not science but fear: that it will ignite moralism about drugs and condemnation of drug users. The solution is not to cleave to the concept of compulsion but to fight moralism directly.
Restricting Reasons: A New Battleground in Abortion Regulation
Authors: Will Jonathan F.
Published: March 2021

The latest trend in abortion restrictions in the United States targets a woman's reasons for terminating a pregnancy. Fourteen states have attempted to enact laws prohibiting abortion on the basis of fetal sex, race, and/or genetic anomaly. These laws are different from regulations tied to a government interest in protecting women's health. Laws that restrict reasons implicate a different set of government interests to be weighed against a woman's constitutional right first recognized in Roe v. Wade. These laws also seek to reframe the nature of the right asserted by the woman. To date, the Supreme Court has declined to address the constitutionality of laws that restrict reasons, and the Court's most recent abortion decisions provide little guidance.

It is possible that a conservative majority of the Supreme Court would uphold a law that prohibits reasons for having an abortion that appear discriminatory. But such laws would be difficult to enforce and therefore may be relegated to policy statements rejecting discriminatory norms as opposed to being effective means of restricting access to abortion.
Remembering Hospice
Authors: Jennings Bruce
Published: March 2021

This book review essay discusses The Crisis of US Hospice Care: Family and Freedom at the End of Life (2019), by Harold Braswell.
Checking in with Neuroethics
Authors: Farah Martha J.
Published: March 2021

Like people, academic fields grow, acquire an identity, establish goals, and ultimately impact the world in various ways. Here we check in with our young friend Neuroethics—a field I want to see develop and thrive. This won't happen if it keeps returning to issues like cognitive enhancement or neural causation of behavior and responsibility, with minor adjustments of its analyses. Neuroethics is at its best when scanning the horizon for new scientific and technical developments that intersect in new ways with ethics and law. Consider the development of open‐ and closed‐loop deep brain stimulation for behavioral disorders. Under what conditions are patients responsible for their behavior when it is influenced by an implanted system? Neuroethics has also increased understanding of people's beliefs and attitudes toward neuroscience and its applications because effective policy must take empirical facts into account.
Does a Public Health Crisis Justify More Research with Incarcerated People?
Authors: Reiter Keramet
Published: March 2021

Covid‐19 has infected thousands and killed hundreds in prisons, jails, and immigration detention facilities across the United States. Responding to this crisis, leading medical researchers have called for expanding opportunities for people in prison to participate in vaccine trials. These calls, like current regulations, focus on individualized risk assessments around consent, coercion, and harm, while ignoring the unnaturalness of deprivation conditions in U.S. prisons. We need new frameworks of analysis that refocus on structural, rather than individual, risk assessments. Integrating structural perspectives—including skepticism of claims of scarcity, avoidance of representational distortions, and attention to institutional agency—into our existing, overly individualistic frameworks might permit the design of more ethical research projects involving people who are incarcerated. Still, the unnatural deprivations of incarceration might be so great that research subjects might need to be removed from prison entirely in order to ethically participate in research.
Beware of white matter hyperintensities causing systematic errors in FreeSurfer gray matter segmentations!
Authors: Dadar Mahsa , Potvin Olivier , Camicioli Richard , Duchesne Simon ,   for the Alzheimer's Disease Neuroimaging Initiative
Published: March 2021

Volumetric estimates of subcortical and cortical structures, extracted from T1‐weighted MRIs, are widely used in many clinical and research applications. Here, we investigate the impact of the presence of white matter hyperintensities (WMHs) on FreeSurfer gray matter (GM) structure volumes and its possible bias on functional relationships. T1‐weighted images from 1,077 participants (4,321 timepoints) from the Alzheimer's Disease Neuroimaging Initiative were processed with FreeSurfer version 6.0.0. WMHs were segmented using a previously validated algorithm on either T2‐weighted or Fluid‐attenuated inversion recovery images. Mixed‐effects models were used to assess the relationships between overlapping WMHs and GM structure volumes and overall WMH burden, as well as to investigate whether such overlaps impact associations with age, diagnosis, and cognitive performance. Participants with higher WMH volumes had higher overlaps with GM volumes of bilateral caudate, cerebral cortex, putamen, thalamus, pallidum, and accumbens areas (p < .0001). When not corrected for WMHs, caudate volumes increased with age (p < .0001) and were not different between cognitively healthy individuals and age‐matched probable Alzheimer's disease patients. After correcting for WMHs, caudate volumes decreased with age (p < .0001), and Alzheimer's disease patients had lower caudate volumes than cognitively healthy individuals (p < .01). Uncorrected caudate volume was not associated with ADAS13 scores, whereas corrected lower caudate volumes were significantly associated with poorer cognitive performance (p < .0001). Presence of WMHs leads to systematic inaccuracies in GM segmentations, particularly for the caudate, which can also change clinical associations. While specifically measured for the Freesurfer toolkit, this problem likely affects other algorithms.
An improved predictive model for postoperative pulmonary complications after free flap reconstructions in the head and neck
Authors: Smith Derek K. , Freundlich Robert E. , Shinn Justin R. , Wood C. Burton , Rohde Sarah L. , McEvoy Matthew D.
Published: March 2021

Background

Commonly used predictive models for postoperative pulmonary complications (PPCs) do not perform when applied to head and neck cases. A head and neck‐specific risk prediction tool is needed.

Methods

Data on 794 free flap head and neck surgery cases at a single center were abstracted from the electronic medical record. Each case was reviewed for the development of PPCs. A predictive model was developed and was then compared to existing predictive models for PPCs.

Results

The least absolute shrinkage and selection operator procedure identified age, alcohol use, history of congestive heart failure, preoperative packed cell volume, preoperative oxygen saturation, and preoperative metabolic equivalents as predictors of PPCs in the head and neck population. The model demonstrated an area under the receiving operating characteristic curve of 0.75 (0.69–0.80) with moderately good calibration. Comparisons to the performance of existing models demonstrate superior performance.

Conclusions

The model for the development of PPCs developed in this article displays superior performance to existing models.
Personalising lung cancer screening: An overview of risk‐stratification opportunities and challenges
Authors: ten Haaf Kevin , van der Aalst Carlijn M. , de Koning Harry J. , Kaaks Rudolf , Tammemägi Martin C.
Published: March 2021

Randomised clinical trials have shown the efficacy of computed tomography lung cancer screening, initiating discussions on whether and how to implement population‐based screening programs. Due to smoking behaviour being the primary risk‐factor for lung cancer and part of the criteria for determining screening eligibility, lung cancer screening is inherently risk‐based. In fact, the selection of high‐risk individuals has been shown to be essential in implementing lung cancer screening in a cost‐effective manner. Furthermore, studies have shown that further risk‐stratification may improve screening efficiency, allow personalisation of the screening interval and reduce health disparities. However, implementing risk‐based lung cancer screening programs also requires overcoming a number of challenges. There are indications that risk‐based approaches can negatively influence the trade‐off between individual benefits and harms if not applied thoughtfully. Large‐scale implementation of targeted, risk‐based screening programs has been limited thus far. Consequently, questions remain on how to efficiently identify and invite high‐risk individuals from the general population. Finally, while risk‐based approaches may increase screening program efficiency, efficiency should be balanced with the overall impact of the screening program. In this review, we will address the opportunities and challenges in applying risk‐stratification in different aspects of lung cancer screening programs, as well as the balance between screening program efficiency and impact.
The molecular structure and role of CCL2 (MCP‐1) and C‐C chemokine receptor CCR2 in skeletal biology and diseases
Authors: Zhu Sipin , Liu Mei , Bennett Samuel , Wang Ziyi , Pfleger Kevin D. G. , Xu Jiake
Published: March 2021

Monocyte chemoattractant protein‐1, also called chemokine (C‐C motif) ligand 2 (CCL2) or small inducible cytokine A2, is an inflammatory mediator capable of recruiting monocytes, memory T cells, and dendritic cells. CCL2 is a member of the CC chemokine superfamily, which binds to its receptor, C‐C motif chemokine receptor‐2 (CCR2), for the induction of chemotactic activity and an increase of calcium influx. It exerts multiple effects on a variety of cells, including monocytes, macrophages, osteoclasts, basophils, and endothelial cells, and is involved in a diverse range of diseases. This review discusses the molecular structure and role of CCL2 and CCR2 in skeletal biology and disease. Molecular structure analyses reveal that CCL2 shares a conserved C‐C motif; however, it has only limited sequence homology with other CCL family members. Likewise, CCR2, as a member of the G‐protein‐coupled seven‐transmembrane receptor superfamily, shares conserved cysteine residues, but exhibits very limited sequence homology with other CCR family members. In the skeletal system, the expression of CCL2 is regulated by a variety of factors, such as parathyroid hormone/parathyroid hormone‐related peptide, interleukin 1b, tumor necrosis factor‐α and transforming growth factor‐beta, RANKL, and mechanical forces. The interaction of CCL2 and CCR2 activates several signaling cascades, including PI3K/Akt/ERK/NF‐κB, PI3K/MAPKs, and JAK/STAT‐1/STAT‐3. Understanding the role of CCL2 and CCR2 will facilitate the development of novel therapies for skeletal disorders, including rheumatoid arthritis, osteolysis and other inflammatory diseases related to abnormal chemotaxis.
Silicone‐induced lymphadenopathy mimicking recurrence of breast cancer on positron emission tomography‐computed tomography, correctly diagnosed on ultrasound
Authors: Cho Eun , Lee Jin Hwa , Park Eun Hwa , Byun Kyung Do , Roh Mee Sook , Baek Hye Jin , Ryu Kyeong Hwa
Published: March 2021

Silicone‐induced lymphadenopathy is a rare complication associated with silicone breast implants. It is usually asymptomatic and found incidentally during imaging. We report a case of silicone lymphadenopathy in a patient who had undergone a mastectomy and breast reconstruction for breast cancer. During follow‐up, a positron emission tomography‐computed tomography examination revealed lymph nodes that were suspicious for cancer recurrence. However, sonography was able to correctly diagnose silicone‐induced lymphadenopathy and exclude cancer metastasis.
Nonsubsampled contourlet transform based tone‐mapping operator to optimize the dynamic range of diatom shells
Authors: Singh Harbinder , Cristobal Gabriel , Blanco Saul , Bueno Gloria , Sanchez Carlos
Published: March 2021

The diatoms have intricate silica‐based cell walls with multi‐scale patterns. High dynamic range (HDR) imaging is widely used to examine the three‐dimensional structure of diatoms for recovering the wide range of contrast and brightness. In order to construct a HDR image of a diatom, multiple images of the specimen are taken at different exposure settings with bright or dark field microscopy. In the proposed method, multi‐scale decomposition based on nonsubsampled contourlet transform is adopted to separate the structured and detailed information of the HDR image. And then, by processing all layers independently, the tone‐mapped image is reconstructed to retain details present in the dark and light regions. Quantitative and qualitative analysis is performed in order to assess the performance of the proposed and seven existing tone‐mapping operators. In analysis, the study indicates that the proposed method enhances the diatom frustules to extract more details.
Morphology of yolk and pericardial sacs in lecithotrophic and matrotrophic nutrition in poeciliid fishes
Authors: Ponce de León José Luis , Uribe Mari Carmen
Published: March 2021

We used histological techniques to describe the morphology of the yolk and pericardial sacs in developing embryos of the lecithotrophic species Girardinus creolus, Gambusia puncticulata, Limia vittata, and Quintana atrizona, in comparison with the extreme matrotrophic Heterandria formosa. In lecithotrophic species, the yolk sac was enlarged and lasted until the final stages of development, while in H. formosa it was completely absorbed soon after fertilization. Lecithotrophic poeciliids showed a pericardial sac with a single layer of blood vessels covering the dorsal surface of the cephalic region only, while H. formosa showed a more complex largely vascularized pericardial sac covering the entire dorsal surface, except the caudal region. In advanced gestation of G. creolus, a vascular plexus of the yolk sac reaches the pharyngeal region, behind the gills, suggesting that the pharynx may play a role in embryonic nutrition in lecithotrophic species. These morphological evidences suggest that matrotrophy derives from lecithotrophy.
Limits of Fat Quantification in the Presence of Iron Overload
Authors: Colgan Timothy J. , Zhao Ruiyang , Roberts Nathan T. , Hernando Diego , Reeder Scott B.
Published: March 2021

Background

Chemical shift encoded magnetic resonance imaging (CSE‐MRI)‐based tissue fat quantification is confounded by increased R2* signal decay rate caused by the presence of excess iron deposition.

Purpose

To determine the upper limit of R2* above which it is no longer feasible to quantify proton density fat fraction (PDFF) reliably, using CSE‐MRI.

Study Type

Prospective.

Population

Cramér–Rao lower bound (CRLB) calculations, Monte Carlo simulations, phantom experiments, and a prospective study in 26 patients with known or suspected liver iron overload.

Field Strength/Sequence

Multiecho gradient echo at 1.5 T and 3.0 T.

Assessment

CRLB calculations were used to develop an empirical relationship between the maximum R2* value above which PDFF estimation will achieve a desired number of effective signal averages. A single voxel multi‐TR, multi‐TE stimulated echo acquisition mode magnetic resonance spectroscopy acquisition was used as a reference standard to estimate PDFF. Reconstructed PDFF and R2* maps were analyzed by one analyst using multiple regions of interest drawn in all nine Couinaud segments.

Statistical Tests

None.

Results

Simulations, phantom experiments, and in vivo measurements demonstrated unreliable PDFF estimates with increased R2*, with PDFF errors as large as 20% at an R2* of 1000 s−1. For typical optimized Cartesian acquisitions (TE1 = 0.75 msec, ΔTE = 0.67 msec at 1.5 T, TE1 = 0.65 msec, ΔTE = 0.58 msec at 3.0 T), an empirical relationship between PDFF estimation errors and acquisition parameters was developed that suggests PDFF estimates are unreliable above an R2* of ~538 s−1 and ~779 s−1 at 1.5 T and 3 T, respectively. This empirical relationship was further investigated with phantom experiments and in vivo measurements, with PDFF errors at an R2* of 1000 s−1 at 3.0 T as large as 10% with TE1 = 1.24 msec, ΔTE = 1.01 msec compared to 3% with TE1 = 0.65 msec, ΔTE = 0.58 msec.

Data Conclusion

We successfully developed a theoretically‐based empirical formula that may provide an easily calculable guideline to identify R2* values above which PDFF is not reliable in research and clinical applications using CSE‐MRI to quantify PDFF in the presence of iron overload.

Level of Evidence

1

Technical Efficacy Stage

1
Polymorphisms of RIG‐I‐like receptor influence HBV clearance in Chinese Han population
Authors: Yao Yinan , Shen Yan , Shao Haifeng , Liu Yuchang , Ji Yan , Du Guoming , Ye Xiangyu , Huang Peng , Chen Haiming
Published: March 2021

Retinoic acid‐inducible gene I‐like receptors (RLRs) play an essential role in human innate immune, which may influence the spontaneous clearance of hepatitis B virus (HBV) infection. We aimed to investigate whether the SNPs in RLR family were associated with HBV spontaneous clearance. The current study included 82 participants with spontaneous clearance, 601 asymptomatic hepatitis B surface antigen (HBsAg) carriers, and 168 participants with chronic hepatitis B (CHB). Six SNPs (DDX58 rs3824456, rs3205166, DHX58 rs2074160, rs2074158, IFIH1 rs2111485, rs3747517) were genotyped to explore their association with HBV spontaneous clearance. Patients carrying the mutant allele C at rs3824456 or A at rs2074160 were more likely to achieve spontaneous clearance compared with asymptomatic HBsAg carriers (additive model: odds ratio [OR] = 0.69, 95% confidence interval [CI] =  0.49–0.97; dominant model: OR = 0.54, 95% CI = 0.31–0.95, respectively). In addition, patients carrying the mutant allele G at rs2111485 were more likely to achieve spontaneous clearance compared with CHB (dominant model: OR = 0.47, 95% CI = 0.25–0.87). The mutations were protective factors for HBV spontaneous clearance. These results suggest the DDX58 rs3824456, DHX58 s2074160, IFIH1 rs2111485 were associated with spontaneous clearance of HBV, which may be predictive markers in the Chinese Han population of HBV.
Assessment of immunity against Yellow Fever virus infections in northeastern Nigeria using three serological assays
Authors: Baba Marycelin M. , Yahaya Khalid M. , Ezra Emmanuel M. , Adamu Musa , Kulloma Bulama M. , Ikusemoran Mayomi , Momoh John P. , Oderinde Bamidele S.
Published: March 2021

Poor systematic surveillance for Yellow Fever virus (YFV) is primarily due to lack of affordable diagnostic facilities in resource‐constrained countries. This study aimed at providing evidence‐based information on immunity against Yellow Fever with a view to assessing the possibility of the recent epidemics persisting in Nigeria. Six hundred patients with febrile illness seeking malaria test in selected hospitals were tested for YFV antibody using three serological assays: ELISA IgM, microneutralization test (MNT) and plaque reduction neutralization test (PRNT). The three assays commonly detected YFV antibody (Ab) in 1.7% patients, MNT: IgM in 8.3%, IgM: PRNT in 7.1%, and MNT: PRNT in 3.2%. Immunity against YF was significantly higher in Bauchi and Borno than Adamawa and children aged 0–9 years compared to 20–29 years. YFV neutralizing antibody (nAb) strongly correlated with the vaccination status of the patients. More unvaccinated patients had nAb compared with the vaccinated. Immunity against YF among treated patients with antibiotic and/or antimalaria before sample collection inversely correlated with the untreated. YVnAb among unvaccinated indicates natural infections. Acute YFV infections were mistaken for malaria and natural infections are ongoing. Individuals aged more than or equal to  20 years should be targeted during mass vaccination campaigns. With low population immunity, repetitive YF epidemics in Nigeria is not yet over. The current policy on Yellow Fever vaccination in Nigeria still leaves a large unimmunized population at the risk of epidemics. Sufficient mass vaccination in combination with National Programme on Immunization remains key to averting YF epidemics.
Solvent‐free mechanochemical preparation of graphene oxide–Fe3O4 and its application in magnetic dispersive solid‐phase extraction of illegal dyes in food samples
Authors: Sha Ou , Liu Hua , Ye Minqiang , Zhu Yuqing , Yao Jiawei , Li Zimin , Zhao Ying
Published: March 2021

A simple, green, and efficient mechanochemical approach was developed herein to prepare tunable magnetic graphene oxide nanoparticles. The obtained nanoparticles were successfully used as adsorbents in a magnetic dispersive solid‐phase extraction method to extract three cationic dyes (i.e., thioflavine T, auramine‐O, and basic orange 2) found in food samples. Our proposed approach also utilized high‐performance liquid chromatography with ultraviolet detection. Several key variables affecting the extraction recovery were investigated. These included the sample pH, amount of extractant, extraction time, sample volume, elution solvent type and volume, and the stability and reusability of the magnetic graphene oxide nanoparticles. Under optimized conditions, the calibration curve was linear at a concentration range of 0.005‐1.0 μg/mL with a correlation coefficient of 0.9992‐0.9996. Moreover, the limits of detection were determined at 0.97‐1.35 μg/mL. The extraction mechanism was investigated via ultraviolet‐visible spectrophotometry and zeta‐potential analyses. The developed method was used to analyze the above‐mentioned cationic dyes in bean products and yellow fish samples. Notably, satisfactory spiked recoveries ranging from 90.7 to 104.9% were achieved.
Africa: A window on challenges and opportunities for head and neck cancer
Authors: Fagan Johannes J.
Published: March 2021

Background

Head and neck cancer occurs predominantly in the Developing World, with significant challenges relating to a high burden of disease, late presentation, and poor access to curative and palliative care.

Aims

This article describes challenges relating to head and neck cancer care in Sub‐Saharan Africa.

Material & Methods

Educational and training innovations that have been undertaken to improve access to cancer care are presented under the following headings: Open Access Educational Resources African Head and Neck Society (AfHNS); African head and neck surgery fellowship training; AfHNS Virtual Tumor Board; The AfHNS Clinical Practice Guidelines for Head & Neck Cancers in Developing Countries and Limited Resource Settings. Concerns are also raised about universally applicable cancer staging systems.

Results

The challenges facing African patients apply to equally to many other parts of the developing world.

Discussion

The challenges facing African patients apply to equally to many other parts of the developing world.

Conclusions

For outcomes of head and neck cancers to be improved globally, a far greater investment needs to be made in education and training to improve access to care in developing countries. To make a meaningful global impact on morbidity and mortality related to HNC, clinicians, academic institutions and professional societies in developed countries need to be sensitive to these developing world challenges and should directly engage in improving access to care through promoting open access educational resources, offering specialist and fellowship training, collaborating with appropriate research, and establishing and strengthening centers of excellence in developing countries.

Level of Evidence

2c “Outcomes research”.
Characterizing the three‐dimensional distribution of schooling reef fish with a portable multibeam echosounder
Authors: Holland Matthew M. , Becker Alistair , Smith James A. , Everett Jason D. , Suthers Iain M.
Published: March 2021

Multispecies schools of small planktivorous fishes are important constituents of reefs and coastal infrastructure; however, determining the extent and distribution of these schools is challenging. Here, we describe a novel use of a low‐cost portable multibeam echosounder from a small vessel, which can concurrently measure detailed bathymetry and the distribution of mid‐water targets with high spatial accuracy, regardless of light availability or water clarity. Fish abundance and biomass are not easily quantified by multibeam echosounders, so we developed a new metric for delineating the gridded horizontal distribution of school thickness, and assessed the metric's efficacy by examining its correlation with mean volume backscattering strength derived from a calibrated 38 kHz split‐beam echosounder (R = 0.67). We measured the distribution of fish school thickness around clusters of large concrete modules of an artificial reef using a multibeam echosounder, complemented with underwater video to aid species identification. The mean distribution of school thickness was mapped around the reef field with generalized additive mixed models. Model spatial predictions indicated schools aggregated around module clusters, rather than individual modules. Dynamic schools of fish in relatively shallow coastal waters (~ 30 m) can be surveyed over 400,000 m2 at 3 m s−1 in just 60 min. Portable multibeam echosounders are an accessible and valuable addition to quantifying the dynamic distributions of coastal fishes around features with high vertical relief.
Delay‐included Turing‐Hopf bifurcation in the diffusive mussel‐algae model
Authors: Jiang Heping
Published: March 2021

In this paper, the main content is the consideration of the dynamics of a diffusive mussel‐algae model with delay subject to Neumann boundary condition. We will analyze the corresponding characteristic equation and study the existence of delay‐induced Hopf bifurcation and steady state bifurcation. What's more, according to the results of Song et al. we calculated the normal form on the center mainfold and obtained the formulae of the delay‐induced Turing‐Hopf bifurcation, and we also investigate the dynamical behaviors near the Turing‐Hopf bifurcation point. Finally, in order to illustrate and extend our theoretical results, some exact numerical simulations are given out as the authentication.
A new perspective for the numerical solution of the Modified Equal Width wave equation
Authors: Başhan Ali , Murat Yağmurlu Nuri , Uçar Yusuf , Esen Alaattin
Published: March 2021

Finding the approximate solutions to natural systems in the branch of mathematical modelling has become increasingly important and for this end various methods have been proposed. The purpose of the present paper is to obtain and analyze the numerical solutions of Modified Equal Width equation (MEW). This equation is one of those equations used to model nonlinear phenomena which has a significant role in several branches of science such as plasma physics, fluid mechanics, optics and kinetics. Firstly, for the discretization of spatial derivatives, a fifth‐order quintic B‐spline based scheme is directly implemented. Secondly, a forward finite difference formula is applied for the temporal discretization of derivatives with respect to time. Simulation results establish the validity and applicability of the suggested technique for a wide range of nonlinear equations. Then, the newly obtained theoretical consequences are numerically justified by the simulations and test problems. These illustrative test problems are presented verifying the superiority of the newly presented scheme compared to other existing schemes and techniques. The suggested method with symbolic computational software such as, Matlab, is proven as an effective way to obtain the soliton solutions of several nonlinear partial differential equations (PDEs). Finally, the newly obtained results are presented graphically to justify the approximate findings.
Energy estimates to the Cauchy problem of a weakly damped Klein‐Gordon equation with variable‐exponent nonlinearity
Authors: Mustafa Muhammad I.
Published: March 2021

In we consider the following Klein‐Gordon equation

in
 × (0, T) with a nonlinear feedback having a variable exponent m(x) and a time‐dependent coefficient α(t). We use the multiplier method to establish energy decay results depending on both m and α.
The effective equations for the ultrasonic response of wet cortical bone
Authors: Blaszczyk Mischa , Pertsch Gilbert Robert , Hackl Klaus
Published: March 2021

We outline the mathematical model of the ultrasonic response of wet cortical bone and its time‐harmonic formulation. We employ an energetic approach based on the Reuss bound of the free energy of a porous material consisting of a piezo‐electric solid and a conducting fluid part. Magnetic effects are taken into consideration. Corresponding boundary value problems are stated, and associated theorems are established. A conclusion is included concerning future developments of this formulation.
Average sampling and reconstruction for signals in shift‐invariant subspaces of weighted mixed Lebesgue spaces
Authors: Wang Suping , Zhang Jiaxing
Published: March 2021

In this paper, we mainly study the average sampling problem for signals in a shift‐invariant subspace of weighted mixed Lebesgue space. First, the sampling stability for two kinds of average sampling functionals is established. Then, two iterative reconstruction algorithms with exponential convergence are presented for recovering the shift‐invariant signals from the corresponding average samples.
Orbital angular momentum wave generation/detection based on planar multi‐slot‐spiral circularly polarized antenna
Authors: Koohkan Ehsan , Jarchi Saughar , Ghorbani Ayaz , Bod Mohammad
Published: March 2021

Orbital angular momentum (OAM) as vortex wave has potential application for dense communication. A multi‐slot antenna is proposed based on Archimedean spirals to generate/detect the OAM waves. The antenna equips three radiation slots in a disk‐manner to realize three different OAM modes simultaneously. A serial‐fed microstrip array is designed for circularly polarized (CP) radiation. The lengths of the slots and microstrip lines are chosen to radiate at 3.5 GHz with 20% fractional bandwidth. So, it can identify the receiving modes of vortex wave with this mechanism. A prominent spiral phase plane is observed for the generated OAM wave. In addition, the far‐field pattern presents a doughnut‐shape beam. The whole antenna is fabricated on a 13 cm printed circuit disk board. Both the experimental and simulation results show that the proposed antenna has valuable features to produce different vortex modes.