bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of cementless femoral stem level on mediolateral projection radiographs
Authors: Burneko Marie , Hudson Caleb C. , Beale Brian S.
Published: April 2020

Objective

To evaluate the accuracy of measuring cementless femoral stem level on mediolateral projection radiographs.

Study design

Benchtop cadaveric.

Sample population

Twelve canine cadaver femurs.

Methods

Cementless femoral stems were inserted into 12 canine cadaver femurs at three levels of subsidence. Mediolateral radiographs were obtained for each femur at 0°, 10°, and − 10° frontal plane angulation and at 0°, 15°, 30°, −15°, and − 30° axial plane rotation. Stem level was measured physically on specimens and on radiographs, and a proportion was used to calculate corrected stem level. Stem level was assessed relative to the greater trochanter and relative to the intertrochanteric fossa. Analysis of variance tests were used to compare actual, radiographically measured, and corrected stem level.

Results

No differences were detected between radiographically measured and actual stem level relative to the greater trochanter at 0°, 15°, 30°, and − 30° axial rotation with 0° frontal plane angulation; introduction of 10° or − 10° frontal plane angulation resulted in differences between radiographically measured and actual stem level. Errors >0.5 mm were observed in 82% of radiographic measurements on the basis of the intertrochanteric fossa. The use of a corrective proportion did not improve the accuracy of radiographic measurements.

Conclusion

Femoral stem level was accurately quantitated on mediolateral projection radiographs in this cadaver model. Frontal plane angulation distorted this measurement.

Clinical significance

Femoral stem subsidence may be assessed on well‐positioned mediolateral projection radiographs if the landmarks are visible.
Impact of breed on canine humeral condylar fracture configuration, surgical management, and outcome
Authors: Sanchez Villamil Carlos , Phillips Andrew S. J. , Pegram Camilla L. , O'Neill Dan G. , Meeson Richard L.
Published: April 2020

Objective

To report the prevalence, configuration, risk factors, fixation methods and outcomes after repair of humeral condylar fractures (HCF) in dogs.

Study design

Retrospective nested cohort study.

Sample population

One hundred twelve dogs.

Methods

Medical records of dogs referred between January 2010 and August 2018 were searched for HCF. Demographics, fracture configuration, repair, and complications were obtained from medical records. Radiographs were assessed for fracture reduction, implant positioning, and bone healing. Short‐term radiographic and clinical outcomes, and long‐term owner‐assessed outcome was determined. Associations between these variables were statistically analyzed.

Results

Dogs with HCF represented 112 of 43 325 (0.26%, 95% CI 0.22‐0.31) referrals. French bulldogs and spaniel breeds were predisposed to HCF (P < .02). French bulldogs were 6.58 times (95% CI 1.62‐26.7) more likely than other breeds to have a medial HCF (P = .008). Epicondylar plate fixation was associated with reduced complications compared with lag screws and Kirschner wires (P = .009). Lameness was scored as 1 of 5 (median) in the 85 dogs with initial follow‐up (median 6 weeks) after HCF repair. Outcome was considered excellent in 26 of 31 dogs with long‐term follow‐up (median 36 months).

Conclusion

French bulldogs and spaniels were predisposed to HCF, and medial HCF were more common in French bulldogs. Epicondylar plate fixation was associated with reduced complications.

Clinical significance

French bulldogs are predisposed to HCF, including medial HCF. Epicondylar plate fixation is recommended over other epicondylar fixation methods to reduce complications.
Effects of acoustic stimulation on biochemical parameters in the digestive gland of Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819)
Authors: Vazzana Mirella , Ceraulo Maria , Mauro Manuela , Papale Elena , Dioguardi Maria , Mazzola Salvatore , Arizza Vincenzo , Chiaramonte Marco , Buscaino Giuseppa
Published: April 2020

Underwater sounds generated by anthropogenic activity can cause behavior changes, temporary loss of hearing, damage to parts of the body, or death in a number of marine organisms and can also affect healing and survival. In this study, the authors examined the effects of high-frequency acoustic stimulations on a number of biochemical parameters in the Mediterranean mussel, Mytilus galloprovincialis. During the experiment, animals were placed in a test tank and exposed to acoustic signals [a linear sweep ranging from 100 to 200 kHz and lasting 1 s, with a sound pressure level range of between 145 and 160 dBrms (re 1μParms)] for 3 h. Total haemocyte count was assessed and glucose levels, cytotoxic activity and enzyme activity (alkaline phosphatase, esterase and peroxidase) in the digestive gland were measured. For the first time, this study suggests that high-frequency noise pollution has a negative impact on biochemical parameters in the digestive gland.
How Coaches See Conscientiousness-Related Traits and Their Impact on Athletes’ Training and Expertise Development
Authors: Tedesqui Rafael A. B. , Young Bradley W.
Published: April 2020

Conscientiousness, grit, and self-control are personality characteristics that have been shown to differentially predict several criteria of expertise development, including athletes’ deliberate practice and higher skill levels. However, little is known about coaches’ views on (a) how these conscientiousness-related traits translate into behaviors within the daily training environment or (b) the relevance of these traits for athletes’ quantity and quality of practice and development toward expert levels of performance. To fill these gaps, semistructured open-ended interviews were conducted with 11 high-performance coaches (nine males and two females) of individual and team sports, and national and international competitive levels. The interviews were analyzed using thematic analysis guidelines. The coaches’ descriptions evidenced some overlap between the investigated traits and a partial view of these constructs. They generally believed that grit, conscientiousness, and self-control play critical roles on athletes’ quality of practice and skill development. Notably, the coaches highlighted that tendencies to persevere despite adversity and mindfully use self-regulated processes seem to be powerful predispositions for athletes’ development toward expert performance levels. The results suggested potential mechanisms to help explain the observed relationship between conscientiousness-related traits and athletes’ quality of practice and skill development.
Antimicrobial Activity of Ceftolozane-Tazobactam and Comparators against Clinical Isolates of Haemophilus influenzae from the United States and Europe
Authors: Sader Helio S. , Carvalhaes Cecilia G. , Duncan Leonard R. , Shortridge Dee
Published: April 2020

Nine hundred
Haemophilus influenzae
clinical isolates from 83 U.S. and European medical centers were tested for susceptibility by reference broth microdilution methods against ceftolozane-tazobactam and comparators. Results were stratified by β-lactamase production and infection type. Overall, ceftolozane-tazobactam MIC
50/90
values were 0.12/0.25 mg/liter, and 99.0% of isolates were inhibited at the susceptible breakpoint of ≤0.5 mg/liter; the highest MIC value was only 2 mg/liter.
AccR, a TetR Family Transcriptional Repressor, Coordinates Short-Chain Acyl Coenzyme A Homeostasis in
Streptomyces avermitilis
Authors: Lyu Mengya , Cheng Yaqing , Han Xiao , Wen Ying , Song Yuan , Li Jilun , Chen Zhi
Published: April 2020

Acyl-CoA carboxylases play key roles in primary and secondary metabolism. However, the regulation of ACCase genes transcription in
Streptomyces
spp. remains unclear. Here, we demonstrated that AccR responded to intracellular acetyl-, propionyl-, and methylcrotonyl-CoA availability and mediated transcription of the genes related to production and assimilation of these compounds in
S. avermitilis
. When intracellular concentrations of these compounds are low, AccR binds to target genes and represses their transcription, resulting in low production of malonyl- and methylmalonyl-CoAs. When intracellular acetyl-, propionyl-, and methylcrotonyl-CoA concentrations are high, these compounds bind to AccR to dissociate AccR from target DNA, promoting the conversion of these compounds to malonyl- and methylmalonyl-CoAs. This investigation revealed how AccR coordinates short-chain acyl-CoA homeostasis in
Streptomyces
.
Evaluation of Phosphoethanolamine Cellulose Production among Bacterial Communities Using Congo Red Fluorescence
Authors: Thongsomboon Wiriya , Werby Sabrina H. , Cegelski Lynette
Published: April 2020

Bacterial biofilms are surface-associated communities of bacterial cells enmeshed in an extracellular matrix (ECM). The biofilm lifestyle results in physiological heterogeneity across the community, promotes persistence, and protects cells from external insults such as antibiotic treatment. Escherichia coli was recently discovered to produce a chemically modified form of cellulose, phosphoethanolamine (pEtN) cellulose, which contributes to the formation of its extracellular matrix and elaboration of its hallmark wrinkled macrocolony architectures. Both pEtN cellulose and unmodified cellulose bind dyes such as calcofluor white and Congo red (CR). Here, we present the use of CR fluorescence to distinguish between pEtN cellulose and unmodified cellulose producers. We demonstrate the utility of this tool in the evaluation of a uropathogenic E. coli clinical isolate that appeared to produce curli and a cellulosic component but did not exhibit macrocolony wrinkling. We determined that lack of macrocolony wrinkling was attributed to a single-nucleotide mutation and introduction of a stop codon in bcsG, abrogating production of BcsG, the pEtN transferase. Thus, this work underscores the important contribution of the pEtN cellulose modification to the E. coli agar-based macrocolony wrinkling phenotype and introduces a facile approach to distinguish between modified and unmodified cellulose.

IMPORTANCE E. coli bacteria produce amyloid fibers, termed curli, and a cellulosic component to assemble biofilm communities. Cellulose is the most abundant biopolymer on Earth, and we recently discovered that the cellulosic component in E. coli biofilms was not standard cellulose, but a newly identified cellulosic polymer, phosphoethanolamine cellulose. Studies involving the biological and functional impact of this cellulose modification among E. coli and other organisms are just beginning. Convenient methods for distinguishing pEtN cellulose from unmodified cellulose in E. coli and for estimating production are needed to facilitate further research. Dissecting the balance of pEtN cellulose and curli production by E. coli commensal strains and clinical isolates will improve our understanding of the host microbiome and of factors contributing to bacterial pathogenesis.
Multicenter Clinical Evaluation of the Revogene Strep A Molecular Assay for Detection of Streptococcus pyogenes from Throat Swab Specimens
Authors: Banerjee D. , Michael J. , Schmitt B. , Salimnia H. , Mhaissen N. , Goldfarb D. M. , Lachance P. , Faron M. L. , Aufderheide T. , Ledeboer N. , Weissfeld A. , Selvarangan R.
Published: April 2020

Group A streptococcus (GAS) species cause bacterial pharyngitis in both adults and children. Early and accurate diagnosis of GAS is important for appropriate antibiotic therapy to prevent GAS sequalae. The Revogene Strep A molecular assay (Meridian Bioscience Canada Inc, Quebec City, QC, Canada) is an automated real-time PCR assay for GAS detection from throat swab specimens within approximately 70 min. This multicenter prospective study evaluated the performance of the Revogene Strep A molecular assay compared to that of bacterial culture.
Henipavirus W Proteins Interact with 14-3-3 To Modulate Host Gene Expression
Authors: Edwards Megan R. , Hoad Mikayla , Tsimbalyuk Sofiya , Menicucci Andrea R. , Messaoudi Ilhem , Forwood Jade K. , Basler Christopher F.
Published: April 2020

Nipah virus (NiV) and Hendra virus (HeV), members of the
Henipavirus
genus, are recently emerged, highly lethal zoonotic pathogens that cause yearly outbreaks. NiV and HeV each encode a W protein that has roles in regulating host signaling pathways, including antagonism of the innate immune response. However, the mechanisms used by W to regulate these host responses are not clear. Here, characterization of the interaction of NiV and HeV W with 14-3-3 identifies modulation of 14-3-3-regulated host signaling pathways not previously associated with W, suggesting new avenues of research. The cocrystal structure of the NiV W:14-3-3 complex, as only the second structure of a 14-3-3 mode III interactor, provides further insight into this less-well-understood 14-3-3 binding motif.
Simian Immunodeficiency Virus-Infected Memory CD4+T Cells Infiltrate to the Site of Infected Macrophages in the Neuroparenchyma of a Chronic Macaque Model of Neurological Complications of AIDS
Authors: Lee Cheri A. , Beasley Erin , Sundar Karthikeyan , Smelkinson Margery , Vinton Carol , Deleage Claire , Matsuda Kenta , Wu Fan , Estes Jake D. , Lafont Bernard A. P. , Brenchley Jason M. , Hirsch Vanessa M.
Published: April 2020

While the use of combination antiretroviral therapy effectively suppresses systemic viral replication in the body, neurocognitive disorders as a result of HIV infection of the central nervous system (CNS) remain a clinical problem. Therefore, the use of nonhuman primate models is necessary to study mechanisms of neuropathogenesis. The neurotropic, molecular clone SIVsm804E-CL757 (CL757) results in neuroAIDS in 50% of infected rhesus macaques approximately 1 year postinfection. Using CL757-infected macaques, we investigate disease progression by examining subsets of cells within the CNS that were targeted by CL757 and could potentially serve as viral reservoirs. By isolating mononuclear cells from the brains of SIV-infected rhesus macaques with and without encephalitis, we show that immune cells invade the neuroparenchyma and increase in number in the CNS in animals with SIV-induced encephalitis (SIVE). Of these cells, both brain macrophages and brain memory CD4+T cells harbor replication-competent SIV DNA; however, only brain CD4+T cells harbored SIV DNA in animals without SIVE. These findings support use of CL757 as an important model to investigate disease progression in the CNS and as a model to study virus reservoirs in the CNS.
Conductance Mechanisms of Rapidly Desensitizing Cation Channelrhodopsins from Cryptophyte Algae
Authors: Sineshchekov Oleg A. , Govorunova Elena G. , Li Hai , Wang Yumei , Melkonian Michael , Wong Gane K.-S. , Brown Leonid S. , Spudich John L.
Published: April 2020

Cation channelrhodopsins, light-gated channels from flagellate green algae, are extensively used as optogenetic photoactivators of neurons in research and recently have progressed to clinical trials for vision restoration. However, the molecular mechanisms of their photoactivation remain poorly understood. We recently identified cryptophyte cation channelrhodopsins, structurally different from those of green algae, which have separately evolved to converge on light-gated cation conductance. This study reveals diversity within this new protein family and describes a subclade with unusually rapid desensitization that results in short transient photocurrents in continuous light. Such transient currents have not been observed in the green algae channelrhodopsins and are potentially useful in optogenetic protocols. Kinetic UV-visible (UV-vis) spectroscopy and photoelectrophysiology reveal that the desensitization is caused by rapid accumulation of a nonconductive photointermediate in the photochemical reaction cycle. The absorption maximum of the intermediate is 330 nm, the shortest wavelength reported in any rhodopsin, indicating a novel chromophore structure.
Critical Role of Zur and SmtB in Zinc Homeostasis of Mycobacterium smegmatis
Authors: Goethe Elke , Laarmann Kristin , Lührs Janita , Jarek Michael , Meens Jochen , Lewin Astrid , Goethe Ralph
Published: April 2020

Zinc is crucial for many biological processes, as it is an essential cofactor of enzymes and a structural component of regulatory and DNA binding proteins. Hence, all living cells require zinc to maintain constant intracellular levels. However, in excess, zinc is toxic. Therefore, cellular zinc homeostasis needs to be tightly controlled. In bacteria, this is achieved by transcriptional regulators whose activity is mediated via zinc-dependent conformational changes promoting or preventing their binding to DNA. SmtB and Zur are important antagonistically acting bacterial regulators in mycobacteria. They sense changes in zinc concentrations in the femtomolar range and regulate transcription of genes for zinc acquisition, storage, and export. Here, we analyzed the role of SmtB and Zur in zinc homeostasis in
Mycobacterium smegmatis
. Our results revealed novel insights into the transcriptional processes of zinc homeostasis in mycobacteria and their regulation.
Longitudinal trends in the quality, effectiveness and attributes of highly rated smartphone health apps
Authors: Mercurio Mara , Larsen Mark , Wisniewski Hannah , Henson Philip , Lagan Sarah , Torous John
Published: April 2020

Background

While there are numerous mental health apps on the market today, less is known about their safety and quality. This study aims to offer a longitudinal perspective on the nature of high visibility apps for common mental health and physical health conditions.

Methods

In July 2019, we selected the 10 top search-returned apps in the Apple App Store and Android Google Play Store using six keyword terms: depression, anxiety, schizophrenia, addiction, high blood pressure and diabetes. Each app was downloaded by two authors and reviewed by a clinician, and the app was coded for features, functionality, claims, app store properties, and other properties.

Results

Compared with 1 year prior, there were few statistically significant changes in app privacy policies, evidence and features. However, there was a high rate of turnover with only 34 (57%) of the apps from the Apple’s App Store and 28 (47%) from the Google Play Store remaining in the 2019 top 10 search compared with the 2018 search.

Discussion

Although there was a high turnover of top search-returned apps between 2018 and 2019, we found that there were few significant changes in features, privacy, medical claims and other properties. This suggests that, although the highly visible and available apps are changing, there were no significant improvements in app quality or safety.
N6-methyladenosine mRNA methylation of PIK3CB regulates AKT signalling to promote PTEN-deficient pancreatic cancer progression
Authors: Tian Jianbo , Zhu Ying , Rao Meilin , Cai Yimin , Lu Zequn , Zou Danyi , Peng Xiating , Ying Pingting , Zhang Ming , Niu Siyuan , Li Yue , Zhong Rong , Chang Jiang , Miao Xiaoping
Published: April 2020

Objective

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers worldwide. Thus far, most drugs have failed to significantly improve patient survival. N6-methyladenosine (m6A) plays an important role in the progression of PDAC, but its aberrant regulation driven by germline variants in human diseases remains unclear.

Design

We first performed an exome-wide association analysis in 518 PDAC patients with overall survival and replicated in an independent population containing 552 PDAC patients. Then, a series of biochemical experiments in vitro and in vivo were conducted to investigate potential mechanisms of the candidate variant and its target gene PIK3CB underlying the PDAC progression. Moreover, the PIK3CB-selective inhibitor KIN-193 was used to block PDAC tumour growth.

Results

We identified a missense variant rs142933486 in PIK3CB that is significantly associated with the overall survival of PDAC by reducing the PIK3CB m6A level, which facilitated its mRNA and protein expression levels mediated by the m6A ‘writer’ complex (METTL13/METTL14/WTAP) and the m6A ‘reader’ YTHDF2. The upregulation of PIK3CB is widely found in PDAC tumour tissues and significantly correlated with the poor prognosis of PDAC, especially in PTEN-deficient patients. We further demonstrated that PIK3CB overexpression substantially enhanced the proliferation and migration abilities of PTEN-deficient PDAC cells and activated AKT signalling pathway. Remarkably, KIN-193, a PIK3CB-selective inhibitor, is shown to serve as an effective anticancer agent for blocking PTEN-deficient PDAC.

Conclusions

These findings demonstrate aberrant m6A homoeostasis as an oncogenic mechanism in PDAC and highlight the potential of PIK3CB as a therapeutic target for this disease.
SMARCAfamily of genes
Authors: Chetty Runjan , Serra Stefano
Published: April 2020

TheSMARCAsubgroup of genes belong to the SWI1/SNF1 family that are responsible chromatin remodelling and repair. Inactivating mutations in the mainSMARCAgenesA2andA4lead to loss of expression of their respective proteins within the nucleus and, as such have characterised a set of malignancies that are underpinned by SMARCA-deficiency.

The morphology of these tumours ranges from small to large epithelioid cells, giant cells and rhabdoid cells. The rhabdoid cells are frequently present in these tumours but are not a sine qua non for the diagnosis. Most of these tumours are undifferentiated or dedifferentiated, high-grade pleomorphic carcinomas. Focally, areas of better differentiation can be seen. The initial description of a SMARCA4-deficient malignancy was the small cell carcinoma of the ovary, hypercalcaemic type. Subsequently, tumours fitting this characteristic morphology and immunophenotype have been described in the lung, thoracic cavity, endometrium and sinonasal tract, gastrointestinal tract and kidney. Immunohistochemical loss of SMARCA2 and SMARCA4 may occur concomitantly or independently of each other.

SMARCA-deficient malignant tumours represent a unique subset of tumours with typical morphological and immunohistochemical findings.
Central nervous system complications associated with immune checkpoint inhibitors
Authors: Vogrig Alberto , Muñiz-Castrillo Sergio , Joubert Bastien , Picard Geraldine , Rogemond Veronique , Marchal Cécile , Chiappa Anne Marie , Chanson Eve , Skowron François , Leblanc Amelie , Ducray François , Honnorat Jerome
Published: April 2020

Objective

To describe the spectrum and outcome of central nervous system complications associated with immune checkpoint inhibitors (CNS-ICI).

Methods

Patients with CNS-ICI were identified and their characteristics compared with ICI-related peripheral neuropathy (PN-ICI).

Results

We identified 19 patients with CNS-ICI. The patients were receiving nivolumab (n=8), pembrolizumab (n=6), a combination of ipilimumab-nivolumab (n=3), ipilimumab-durvalumab (n=1), or atezolizumab (n=1). Underlying malignancies included non-small-cell lung cancer (n=8), melanoma (n=3), and other less common tumours (n=8). Neurological phenotypes were limbic encephalitis (n=8), meningoencephalitis (n=4) and cerebellitis (n=4). Two patients developed isolated confusion and one parkinsonism. Associated autoantibodies included onconeural (Ma2, n=7; Hu, n=1), astrocytic (glial fibrillar acidic protein, n=2) and neuronal surface (contactin-associated protein-like 2, n=1) specificities. ICIs were withheld and corticosteroid treatment was given in all cases. Five patients received intravenous immunoglobulin, two rituximab, one plasmapheresis and one infliximab. Overall, six patients died. Readministration of ICI was attempted in three patients, without further relapses. Non-small-cell lung cancer was significantly more frequent in patients with CNS-ICI (p<0.01), while melanoma and ipilimumab treatment were more common in PN-ICI (p<0.01 and p=0.01). Conversely, CNS-ICI cases were more frequently antibody-positive than PN-ICI (p<0.01) and showed a strong trend towards poorer outcome (p=0.053).

Conclusion

Three main clinical phenotypes characterise CNS complications of ICIs, each with distinct immunological background, disease course and response to treatment. Other clinical manifestations (including parkinsonism and steroid-responsive confusion) are also possible. Underlying cancers, antibody prevalence and outcome appear different from those of patients with PN-ICI.
Centrifuge modelling of static liquefaction in submarine slopes: scaling law dilemma
Authors: Zhang Weiyuan , Askarinejad Amin
Published: April 2020

The scaling laws for the centrifuge modelling of the initiation and propagation of static liquefaction in submerged slopes are investigated in this paper. A theoretical model is developed to analytically determine the scaling factor of fluid viscosity in simulating the onset of static liquefaction by detailed analysis of the hydromechanical processes at the grain scale. Based on this, a fluid with a viscosity of [Formula: see text]-times that of water ([Formula: see text]-fluid) is suggested, where N is the geometrical scaling factor in centrifuge modelling. A fluid with a viscosity of N-times that of water (N-fluid) was adopted for simulating dynamic events in the centrifuge; N-fluid is used and suggested by previous researchers. Centrifuge tests were designed to examine and verify the scaling factors for pore fluid viscosity in simulating the onset of static liquefaction and the post-liquefaction behaviour of subaqueous landslides. These tests were performed at 10g, 30g, and 50g conditions, with [Formula: see text]-fluid, N-fluid or water, where g is the Earth’s gravitational acceleration. Results confirm that the correct scaling factors (prototype/model) for pore fluid viscosity are [Formula: see text] and 1/N for investigating the onset of static liquefaction and the post-failure behaviour of the submarine slopes, respectively.
Applying unmanned aerial vehicles (UAVs) to map shrubland structural attributes in northern Patagonia, Argentina
Authors: Gonzalez Musso Romina F. , Oddi Facundo J. , Goldenberg Matías G. , Garibaldi Lucas A.
Published: April 2020

Unmanned aerial vehicles (UAVs) have gained attention for forestry applications in recent years. These technologies provide ultrahigh-resolution spatial data for detailed mapping of forest structure, among other forestry applications. UAVs have mainly been tested in high-value timber stands, but little is known about their performance in other woody ecosystems such as shrublands that also provide key ecosystem services. Field measurements in shrublands are time-consuming, so UAVs could be used instead to provide data for shrubland management and conservation. We tested whether UAVs could map common structural attributes in shrublands of northern Patagonia. We specifically evaluated the capability of UAV point clouds for mapping (i) canopy height, (ii) stand density, (iii) basal area, and (iv) volume. The agreement with the field measurements was satisfactory (R2 was up to 0.95 and relative root mean square error (rRMSE) ranged between 12% and 39%) and comparable with those found for coniferous forests in similar studies. This study is a first attempt to characterize the structure of Patagonian shrublands using UAV data. Despite the challenges and methodological aspects that need to be solved, our results encourage the use of UAVs in these types of ecosystems.
Bound on Lyapunov exponent in $$c=1$$ matrix model
Authors: Morita Takeshi
Published: April 2020

Classical particle motions in an inverse harmonic potential show the exponential sensitivity to initial conditions, where the Lyapunov exponent $$\lambda _L$$λL is uniquely fixed by the shape of the potential. Hence, if we naively apply the bound on the Lyapunov exponent $$\lambda _L \le 2\pi T/ \hbar $$λL≤2πT/ħ to this system, it predicts the existence of the bound on temperature (the lowest temperature) $$T \ge \hbar \lambda _L/ 2\pi $$T≥ħλL/2π and the system cannot be taken to be zero temperature when $$\hbar \ne 0$$ħ≠0. This seems a puzzle because particle motions in an inverse harmonic potential should be realized without introducing any temperature but this inequality does not allow it. In this article, we study this problem in N non-relativistic free fermions in an inverse harmonic potential ($$c=1$$c=1 matrix model). We find that thermal radiation is induced when we consider the system in a semi-classical regime even though the system is not thermal at the classical level. This is analogous to the thermal radiation of black holes, which are classically non-thermal but behave as thermal baths quantum mechanically. We also show that the temperature of the radiation in our model saturates the inequality, and thus, the system saturates the bound on the Lyapunov exponent, although the system is free and integrable. Besides, this radiation is related to acoustic Hawking radiation of the fermi fluid.
Volkov–Akulov–Starobinsky supergravity revisited
Authors: Aldabergenov Yermek
Published: April 2020

We find new realizations of Volkov–Akulov–Starobinsky supergravity, i.e. Starobinsky inflationary models in supergravity coupled to a nilpotent superfield describing Volkov–Akulov goldstino. Our constructions are based on the no-scale Kähler potential $$K=-3\log (T+\overline{T})$$K=-3log(T+T¯) for the inflaton field, and can describe de Sitter vacuum after inflation where supersymmetry is broken by the goldstino auxiliary component. In fact, we show that a more general class of models with $$K=-\alpha \log (T+\overline{T})$$K=-αlog(T+T¯) for $$3\le \alpha \lesssim 6.37$$3≤α≲6.37 can accomodate Starobinsky-like inflation with the universal prediction $$n_s\simeq 1-\frac{2}{N_e}$$ns≃1-2Ne and $$r\simeq \frac{4\alpha }{(\alpha -2)^2N_e^2}$$r≃4α(α-2)2Ne2, while for $$6.37\lesssim \alpha \lesssim 7.23$$6.37≲α≲7.23 viable hilltop inflation is possible (with $$n_s$$ns and r close to the above expressions). We derive the full component action and the masses of sinflaton, gravitino, and inflatino that are generally around the inflationary Hubble scale. Finally, we show that one of our models can be dualized into higher-derivative supergravity with constrained chiral curvature superfield.
Particle event generator: a simple-in-use system PEGASUS version 1.0
Authors: Lipatov A. V. , Malyshev M. A. , Baranov S. P.
Published: April 2020

pegasusis a parton-level Monte-Carlo event generator designed to calculate cross sections for a wide range of hard QCD processes at high energyppand$$p\bar{p}$$pp¯collisions, which incorporates the dynamics of transverse momentum dependent (TMD) parton distributions in a proton. Being supplemented with off-shell production amplitudes for a number of partonic subprocesses and provided with necessary TMD gluon density functions, it produces weighted or unweighted event records which can be saved as a plain data file or a file in a commonly used Les Houches Event format. A distinctive feature of thepegasusis an intuitive and extremely user friendly interface, allowing one to easily implement various kinematical cuts into the calculations. Results can be also presented “on the fly” with built-in toolpegasus plotter. A short theoretical basis is presented and detailed program description is given.
Tunable biaxial hyperbolic dispersion and negative refraction in graphite
Authors: Wu Hongya , Jia Jiayu , Xu Liang , Zhou Ruoshan , Qin Guoqiang , Qin Shengjian , Yu Gang , Yang Zhigang , Zhang Guanglei , Zhou Ji
Published: April 2020

In recent years, significant attention has been attracted to hyperbolic (or indefinite) materials resulting from their extraordinary optical properties, such as all-angle negative refraction. Here, tunable biaxial hyperbolic dispersion and negative refraction were found in graphite crystal. First principles were used to calculate the permittivity of graphite in [Formula: see text]-, [Formula: see text]- and [Formula: see text]-directions, the results indicate that graphite crystals exhibit indefinite dielectric constant tensor in certain frequency range. By adjusting strain, the optical properties of materials changed, and even switched from hyperbolic to elliptical materials in some frequency. This work demonstrates the feasibility of achieving high-performance tunable biaxial natural hyperbolic materials which can be used in various ways.
Biological plausibility for interactions between dietary fat, resveratrol, ACE2, and SARS-CoV illness severity
Authors: Horne Justine R. , Vohl Marie-Claude
Published: April 2020

The angiotensin converting enzyme-2 (ACE2) cellular receptor is responsible for the pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), thus impacting the entrance and clearance of the virus. Studies demonstrate that upregulation of ACE2 has a protective effect on SARS-CoV-2 illness severity. Moreover, animal studies demonstrate that dietary intake can modulate ACE2 gene expression and function. A high intake of resveratrol may have a protective role, upregulating ACE2, whereas a high intake of dietary fat may have a detrimental role, downregulating ACE2. As such, we postulate on the biological plausibility of interactions between dietary fat and/or resveratrol and ACE2 gene variations in the modulation of SARS-CoV-2 illness severity. We call to action the research community to test this plausible interaction in a sample of human subjects.
Dopamine D2 receptor activator quinpirole protects against trypsinogen activation during acute pancreatitis via upregulating HSP70
Authors: Ye Xin , Han Xiao , Li Bin , Dai Juanjuan , Wu Zengkai , He Yan , Wen Li , Hu Guoyong
Published: April 2020

The current study demonstrated that activation of DRD2 by quinpirole protects against trypsinogen activation in the in vitro and in vivo setting of acute pancreatitis by upregulating HSP70 and restoring lysosomal degradation via a PP2A-dependent manner, therefore leading to reduced pancreatic injury. These findings provide a new mechanistic insight on the protective effect of DRD2 activation in acute pancreatitis.
Genetic ablation of SLK exacerbates glomerular injury in adriamycin nephrosis in mice
Authors: Woychyshyn Boyan , Papillon Joan , Guillemette Julie , Navarro-Betancourt José R. , Cybulsky Andrey V.
Published: April 2020

Ste20-like kinase SLK is critical for embryonic development and may play an important role in wound healing, muscle homeostasis, cell migration, and tumor growth. Mice with podocyte-specific deletion of SLK show albuminuria and damage to podocytes as they age. The present study addressed the role of SLK in glomerular injury. We induced adriamycin nephrosis in 3- to 4-mo-old control and podocyte SLK knockout (KO) mice. Compared with control, SLK deletion exacerbated albuminuria and loss of podocytes, synaptopodin, and podocalyxin. Glomeruli of adriamycin-treated SLK KO mice showed diffuse increases in the matrix and sclerosis as well as collapse of the actin cytoskeleton. SLK can phosphorylate ezrin. The complex of phospho-ezrin, Na+/H+exchanger regulatory factor 2, and podocalyxin in the apical domain of the podocyte is a key determinant of normal podocyte architecture. Deletion of SLK reduced glomerular ezrin and ezrin phosphorylation in adriamycin nephrosis. Also, deletion of SLK reduced the colocalization of ezrin and podocalyxin in the glomerulus. Cultured glomerular epithelial cells with KO of SLK showed reduced ezrin phosphorylation and podocalyxin expression as well as reduced F-actin. Thus, SLK deletion leads to podocyte injury as mice age and exacerbates injury in adriamycin nephrosis. The mechanism may at least in part involve ezrin phosphorylation as well as disruption of the cytoskeleton and podocyte apical membrane structure.
Intradialytic acid-base changes and organic anion production during high versus low bicarbonate hemodialysis
Authors: Park Sarah , Paredes William , Custodio Matthew , Goel Narender , Sapkota Deepak , Bandla Anusha , Lynn Robert I. , Reddy Suman M. , Hostetter Thomas H. , Abramowitz Matthew K.
Published: April 2020

The use of high dialysate bicarbonate for hemodialysis in end-stage renal disease is associated with increased mortality, but potential physiological mediators are poorly understood. Alkalinization due to high dialysate bicarbonate may stimulate organic acid generation, which could lead to poor outcomes. Using measurements of β-hydroxybutyrate (BHB) and lactate, we quantified organic anion (OA) balance in two single-arm studies comparing high and low bicarbonate prescriptions. In study 1 ( n = 10), patients became alkalemic using 37 meq/L dialysate bicarbonate; in contrast, with the use of 27 meq/L dialysate, net bicarbonate loss occurred and blood bicarbonate decreased. Total OA losses were not higher with 37 meq/L dialysate bicarbonate (50.9 vs. 49.1 meq using 27 meq/L, P = 0.66); serum BHB increased in both treatments similarly ( P = 0.27); and blood lactate was only slightly higher with the use of 37 meq/L dialysate ( P = 0.048), differing by 0.2 meq/L at the end of hemodialysis. In study 2 ( n = 7), patients achieved steady state on two bicarbonate prescriptions: they were significantly more acidemic when dialyzed against a 30 meq/L bicarbonate dialysate compared with 35 meq/L and, as in study 1, became alkalemic when dialyzed against the higher bicarbonate dialysate. OA losses were similar to those in study 1 and again did not differ between treatments (38.9 vs. 43.5 meq, P = 0.42). Finally, free fatty acid levels increased throughout hemodialysis and correlated with the change in serum BHB ( r = 0.81, P < 0.001), implicating upregulation of lipolysis as the mechanism for increased ketone production. In conclusion, lowering dialysate bicarbonate does not meaningfully reduce organic acid generation during hemodialysis or modify organic anion losses into dialysate.
Effect of Silver Nanoparticles on Biofilm Formation and EPS Production of Multidrug‐Resistant Klebsiella pneumoniae
Authors: Siddique Muhammad Hussnain , Aslam Bilal , Imran Muhammad , Ashraf Asma , Nadeem Habibullah , Hayat Sumreen , Khurshid Mohsin , Afzal Muhammad , Malik Imran Riaz , Shahzad Mudassar , Qureshi Umber , Khan Zia Ul Haq , Muzammil Saima
Published: April 2020

Antibiotic resistance against present antibiotics is rising at an alarming rate with need for discovery of advanced methods to treat infections caused by resistant pathogens. Silver nanoparticles are known to exhibit satisfactory antibacterial and antibiofilm activity against different pathogens. In the present study, the AgNPs were synthesized chemically and characterized by UV‐Visible spectroscopy, scanning electron microscopy, and X‐ray diffraction. Antibacterial activity against MDR K. pneumoniae strains was evaluated by agar diffusion and broth microdilution assay. Cellular protein leakage was determined by the Bradford assay. The effect of AgNPs on production on extracellular polymeric substances was evaluated. Biofilm formation was assessed by tube method qualitatively and quantitatively by the microtiter plate assay. The cytotoxic potential of AgNPs on HeLa cell lines was also determined. AgNPs exhibited an MIC of 62.5 and 125 μg/ml, while their MBC is 250 and 500 μg/ml. The production of extracellular polymeric substance decreased after AgNP treatment while cellular protein leakage increased due to higher rates of cellular membrane disruption by AgNPs. The percentage biofilm inhibition was evaluated to be 64% for K. pneumoniae strain MF953600 and 86% for MF953599 at AgNP concentration of 100 μg/ml. AgNPs were evaluated to be minimally cytotoxic and safe at concentrations of 15‐120 μg/ml. The data evaluated by this study provided evidence of AgNPs being safe antibacterial and antibiofilm compounds against MDR K. pneumoniae.
The Effect of Network Structure on Compressive Fatigue Behavior of Unfilled Styrene‐Butadiene Rubber
Authors: Yang Liu , Liu Kaikai , Du Aihua
Published: April 2020

The effect of network structure on dynamic compressive fatigue behavior and static compressive mechanical properties of styrene‐butadiene rubber (SBR) were investigated. A series of SBR compounds with different amounts of sulfur and dicumyl peroxide (DCP) were prepared, and their crosslinking densities were calculated using the Flory–Rehner equation. Compressive fatigue resistance and creep behavior of the vulcanizates were performed on a mechanical testing and simulation (MTS) machine. The fatigue damage surface of SBR vulcanizates before and after a dynamic compressive fatigue test was observed with a scanning electron microscopy (SEM). The results suggested that the surface of the samples was badly damaged as the number of compressive cycles increased. By comparison, compressive fatigue caused less surface damage to sulfur‐cured SBR than to peroxide‐cured SBR. The peroxide‐cured SBR samples showed higher energy dissipation than sulfur‐cured SBR during cyclic compression. The peroxide‐cured SBR showed lower creep strain and compression set than the sulfur‐cured SBR. The ‐Sx‐ linkages provided by the sulfur curing system allow dynamic compressive deformation but suffer from poor static compressive resistance. However, the carbon‐carbon linkages from DCP are irreversible and provide higher resistance to static compressive stress, but they do not show obvious dynamic compressive fatigue resistance.
Galactosamine-Conjugating Zwitterionic Block Copolymer for Reduction-Responsive Release and Active Targeted Delivery of Doxorubicin to Hepatic Carcinoma Cells
Authors: Zhai Jingming , Zhou Biyu , An Yanhui , Lu Binzhong , Fan Yonggang , Li Junbo
Published: April 2020

Nanocarriers with integrated advantage, such as excellent stealth property, active targeting function, and rapid intracellular drug release, are significant for cancer treatment. Herein, a biodegradable zwitterionic triblock copolymer containing disulfide-linked poly-ε-caprolactone and polycarboxybetaine methacrylate (PCB-SS-PCL-SS-PCB) was first synthesized and then partly modified with galactosamine (GAL) for constructing polymeric micelle drug carrier with multifunctionality. Polymeric micelles showed ultralow protein absorption in serum and obvious reduction-responsiveness in the presence of glutathione, provided by the zwitterionic polymer shell and the disulfide bond, respectively. Furthermore, active targeting of the carrier to hepatic carcinoma cells was achieved via GAL ligands on PCB shells due to their specific binding to asialoglycoprotein receptors on the cell surface. As expected, in vivo competition studies demonstrated that doxorubicin- (DOX-) loaded GAL-modified micelles have better anticancer effect in hepatic tumor-bearing mice than free DOX and nontargetable micelles. As a result, this novel multifunctional carrier provides a valuable strategy to design promising anticancer drug delivery systems for liver cancer treatment.
Comparative Analysis of Visual Performance and Optical Quality with a Rotationally Asymmetric Multifocal Intraocular Lens and an Apodized Diffractive Multifocal Intraocular Lens
Authors: Wang Xiao , Tu Haixia , Wang Yong
Published: April 2020

Purpose. To compare the short-term visual outcomes and intraocular optical performance of a rotationally asymmetric multifocal intraocular lens (MIOL) (SBL-3, Lenstec, Inc., Christ Church, Barbados) and an apodized diffractive MIOL (the Acrysof IQ ResTOR SN6AD1, Alcon Laboratories, Inc., Fort Worth, Texas, United States). Methods. A prospective, comparative, nonrandomized, and single-center study. Sixty-eight age-related cataract patients (81 eyes) after phacoemulsification cataract surgery and in-the-bag MIOL implantation were enrolled. Thirty-eight eyes received SBL-3, and 43 eyes received SN6AD1. Ophthalmological evaluation included uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), corrected distance visual acuity (CDVA), modulation transfer function (MTF), Strehl ratio (SR), intraocular aberrations (4 mm optical zone), and defocus curve at 3 months postoperatively. The Chinese version of the visual function index-14 (VF-12-CN) and spectacle independence were assessed in all patients. Results. There was no statistically significant difference between groups in postoperative UDVA (p=0.186). Postoperative UIVA and UNVA were significantly better for the SBL-3 group than for the SN6AD1 group (p<0.01). Statistically significant differences were revealed in defocus levels from –3.50 D to −4.00 D with better visual acuities for the SBL-3 group (p<0.01). For intraocular optical quality outcomes, statistically significant differences between groups were observed in RMS of intraocular total aberrations, coma, and trefoil high-order aberrations, presenting significantly higher values of these parameters in the eyes of the SBL-3 group (p < 0.01). Statistically significant differences were revealed in the MTF values at spatial frequencies of 5 and 10 cycles/degree between groups. There were no significant differences in scores of VF-12-CN, and spectacle independence between the groups (p>0.05). Conclusions. Both MIOLs were able to successfully restore visual function after cataract surgery. SBL-3 provided better UIVA and UNVA with a wider range of intermediate vision.
Plastrum Testudinis Extracts Promote NSC Differentiation into Dopaminergic Neuron by Regulating the Interaction of TET1 and FoxA2
Authors: Zhong Jun , Ye Sen , Zhou Xiaoli , Huang Jiapei , Li Xican , Zhang Saixia , Zhou Jianhong , Chen Dongfeng , Li Caixia
Published: April 2020

In recent years, stem cells have gained much attention for the treatment of neurodegenerative diseases. However, inducing neural stem cell directionally differentiation is a difficult problem in the treatment of Parkinson’s disease (PD) by stem cell therapy. Plastrum Testudinis (PT) can enhance the number of TH‐positive neurons in the PD rat brain substantia nigra, but the underlying mechanism has not been clarified. Here, we aimed at further investigating the mechanism by which PT can promote NSC differentiation into dopaminergic neurons. A rat model of PD was used for detecting the effect of PT on the rat brain substantia nigra in vivo. The results showed the expressions of tyrosine hydroxylase (TH) and TET1 enzyme were increased after treatment with PT. Consequently, Plastrum Testudinis extracts (PTEs) were used for inducing NSC differentiation into dopaminergic neurons ex vivo. During differentiation of NSCs induced by PTE, TH expression was increased, with a concomitant increase in both TET1 and FoxA2. Next, we performed coimmunoprecipitation analysis to examine the interaction between TET1 protein and FoxA2 protein. Our results show that PTE can increase the binding rate of TET1 and FoxA2. Thus, our findings show that PTE can increase the efficiency of NSCs to directionally differentiate into dopaminergic neurons and provide experimental evidence for PT in the treatment of Parkinson’s disease.