bluuebunny/crossref_metadata_2025 huggingface dataset:
Species delimitation in the genus Greenwayodendron based on morphological and genetic markers reveals new species
Authors: Lissambou Brandet‐J. , Couvreur Thomas L.P. , Atteke Christiane , Stévart Tariq , Piñeiro Rosalía , Dauby Gilles , Monthe Franck K. , Ikabanga Davy U. , Sonké Bonaventure , M’batchi Bertrand , Hardy Olivier J.
Published: July 2019

Combining genetic and morphological markers is a powerful approach for species delimitation, much needed in tropical species complexes. Greenwayodendron (Annonaceae) is a widespread genus of trees distributed from West to East African rainforests. Two species and four infra‐specific taxa are currently recognized. However, preliminary genetic studies and morphological observations suggested the occurrence of additional species, undescribed to date. We tested species delimitation within Greenwayodendron by combining morphological and population genetics data. First, a visual inspection of about a thousand specimens suggested the existence of seven morphogroups: four of them occur in Central Africa and overlap in Gabon while three others are allopatric, occurring respectively in West Africa, East Africa, and the islands of São Tomé and Príncipe. Their morphological differentiation was confirmed by analysis of 27 morphological characters coded from 233 herbarium specimens. Second, after genotyping 800 samples at eight nuclear microsatellites, Bayesian clustering analyses (STRUCTURE) identified four genetic clusters corresponding to the well‐sampled morphogroups but failed to separate the three remaining morphogroups represented by few samples. However, we show that this is an inherent limit of the STRUCTURE algorithm, whereas factorial correspondence analysis (FCA) and pairwise FST and RST measures confirmed the genetic differentiation of all morphogroups. We considered that a clear genetic differentiation occurring between sympatric populations advocates for recognizing distinct species following the biological species concept. Our analyses highlight that the current taxonomic treatment of Greenwayodendron underestimates the total number of species. We identified two new species and support separation at the rank of species of two varieties (G. suaveolens subsp. suaveolens var. gabonica, G. suaveolens subsp. suaveolens var. suaveolens) and one subspecies (G. suaveolens subsp. usambaricum). The taxonomic status of specimens collected in São Tomé and Príncipe remains inconclusive, partly due to the limited fertile material available. Our study highlights the strength of combining morphological and population genetics data for discovering new taxa. Guidelines for using genetic clustering approaches in species delimitation are provided.
A CRISPR/Cas9 method to generate heterozygous alleles in Saccharomyces cerevisiae
Authors: EauClaire Steven F. , Webb Christopher J.
Published: July 2019

Saccharomyces cerevisiae is a genetically facile organism, yet multiple CRISPR/Cas9 techniques are widely used to edit its genome more efficiently and cost effectively than conventional methods. The absence of selective markers makes CRISPR/Cas9 editing particularly useful when making mutations within genes or regulatory sequences. Heterozygous mutations within genes frequently arise in the winners of evolution experiments. The genetic dissection of heterozygous alleles can be important to understanding gene structure and function. Unfortunately, the high efficiency of genome cutting and repair makes the introduction of heterozygous alleles by standard CRISPR/Cas9 technique impossible. To be able to quickly and reliably determine the individual phenotypes of the thousands of heterozygous mutations that can occur during directed evolutions is of particular interest to industrial strain improvement research. In this report, we describe a CRISPR/Cas9 method that introduces specific heterozygous mutations into the S. cerevisiae genome. This method relies upon creating silent point mutations in the protospacer adjacent motif site or removing the protospacer adjacent motif site entirely to stop the multiple rounds of genome editing that prevent heterozygous alleles from being generated. This technique should be able to create heterozygous alleles in other diploid yeasts and different allelic copy numbers in polyploid cells.
Removing infrared divergences from two-loop integrals
Authors: Anastasiou Charalampos , Sterman George
Published: July 2019

Abstract

Feynman amplitudes at higher orders in perturbation theory generically have complex singular structures. Notwithstanding the emergence of many powerful new methods, the presence of infrared divergences poses significant challenges for their evaluation. In this article, we develop a systematic method for the removal of the infrared singularities, by adding appropriate counterterms that approximate and cancel divergent limits point-by-point at the level of the integrand. We provide a proof of concept for our method by applying it to master-integrals that are found in scattering amplitudes for representative 2→2 scattering processes of massless particles. We demonstrate that, after the introduction of counterterms, the remainder is finite in four dimensions. In addition, we find in these cases that the complete singular dependence of the integrals can be obtained simply by analytically integrating the counterterms. Finally, we observe that our subtraction method can be also useful in order to extract in a simple way the asymptotic behavior of Feynman amplitudes in the limit of small mass parameters.
Gravitational production of superheavy dark matter and associated cosmological signatures
Authors: Li Lingfeng , Nakama Tomohiro , Sou Chon Man , Wang Yi , Zhou Siyi
Published: July 2019

Abstract

We study the gravitational production of super-Hubble-mass dark matter in the very early universe. We first review the simplest scenario where dark matter is produced mainly during slow roll inflation. Then we move on to consider the cases where dark matter is produced during the transition period between inflation and the subsequent cosmological evolution. The limits of smooth and sudden transitions are studied, respectively. The relic abundances and the cosmological collider signals are calculated.
Differences of methanogenesis between mesophilic and thermophilic in situ biogas-upgrading systems by hydrogen addition
Authors: Zhu Xianpu , Chen Liumeng , Chen Yichao , Cao Qin , Liu Xiaofeng , Li Dong
Published: July 2019

To investigate the differences in microbial community structure between mesophilic and thermophilic in situ biogas-upgrading systems by H2 addition, two reactors (35 °C and 55 °C) were run for four stages according to different H2 addition rates (H2/CO2 of 0:1, 1:1, and 4:1) and mixing mode (intermittent and continuous). 16S rRNA gene-sequencing technology was applied to analyze microbial community structure. The results showed that the temperature is a crucial factor in impacting succession of microbial community structure and the H2 utilization pathway. For mesophilic digestion, most of added H2 was consumed indirectly by the combination of homoacetogens and strict aceticlastic methanogens. In the thermophilic system, most of added H2 may be used for microbial cell growth, and part of H2 was utilized directly by strict hydrogenotrophic methanogens and facultative aceticlastic methanogens. Continuous stirring was harmful to the stabilization of mesophilic system, but not to the thermophilic one.
Nudging the particle filter
Authors: Akyildiz Ömer Deniz , Míguez Joaquín
Published: July 2019

We investigate a new sampling scheme aimed at improving the performance of particle filters whenever (a) there is a significant mismatch between the assumed model dynamics and the actual system, or (b) the posterior probability tends to concentrate in relatively small regions of the state space. The proposed scheme pushes some particles toward specific regions where the likelihood is expected to be high, an operation known asnudgingin the geophysics literature. We reinterpret nudging in a form applicable to any particle filtering scheme, as it does not involve any changes in the rest of the algorithm. Since the particles are modified, but the importance weights do not account for this modification, the use of nudging leads to additional bias in the resulting estimators. However, we prove analytically that nudged particle filters can still attain asymptotic convergence with the same error rates as conventional particle methods. Simple analysis also yields an alternative interpretation of the nudging operation that explains its robustness to model errors. Finally, we show numerical results that illustrate the improvements that can be attained using the proposed scheme. In particular, we present nonlinear tracking examples with synthetic data and a model inference example using real-world financial data.
Energy-efficient genetic algorithm variants of PEGASIS for 3D Wireless Sensor Networks
Authors: Somauroo Aaqil , Bassoo Vandana
Published: July 2019

Due to its boundless potential applications, Wireless Sensor Networks have been subject to much research in the last two decades. WSNs are often deployed in remote environments making replacement of batteries not feasible. Low energy consumption being of prime requisite led to the development of energy-efficient routing protocols. The proposed routing algorithms seek to prolong the lifetime of sensor nodes in the relatively unexplored area of 3D WSNs. The schemes use chain-based routing technique PEGASIS as basis and employ genetic algorithm to build the chain instead of the greedy algorithm. Proposed schemes will incorporate an energy and distance aware CH selection technique to improve load balancing. Clustering of the network is also implemented to reduce number of nodes in a chain and hence reduce delay. Simulation of our proposed protocols is carried out for homogeneous networks considering separately cases for a static base-station inside and outside the network. Results indicate considerable improvement in lifetime over PEGASIS of 817% and 420% for base station inside and outside the network respectively. Residual energy and delay performance are also considered.
AGU Awarded Grant from the Alfred P. Sloan Foundation
Authors:   AGU
Published: July 2019

The 3-year grant will help launch the new AGU Ethics and Equity antiharassment initiative.
Zinc 2-N-methyl N-confused porphyrin: an efficient catalyst for the conversion of CO2 into cyclic carbonates
Authors: Ge Yuansheng , Cheng Guoe , Xu Nanfeng , Wang Weizhou , Ke Hanzhong
Published: July 2019

A zinc 2-N-methyl N-confused porphyrin (Zn(NCP)Cl) catalyst was developed for the solvent-free synthesis of cyclic carbonates from epoxides and CO2.
Poly(lactide-co-glycolide) grafted hyaluronic acid-based electrospun fibrous hemostatic fragments as a sustainable anti-infection and immunoregulation material
Authors: Liu Wen , Xi Guanghui , Yang Xiao , Hao Xiao , Wang Mingshan , Feng Yakai , Chen Hao , Shi Changcan
Published: July 2019

PLGA-HA fibrous fragments are efficient in hemorrhage control and also an optimal amount of azithromycin loading aids the antibacterial and immunoregulation properties of the material.
Two-dimensional ferroelastic topological insulator with tunable topological edge states in single-layer ZrAsX (X = Br and Cl)
Authors: Hu Xiangting , Mao Ning , Wang Hao , Niu Chengwang , Huang Baibiao , Dai Ying
Published: July 2019

Here we predict theoretically that topological edge states can be significantly tuned by switching the ferroelastic ordering in a two-dimensional (2D) topological insulator.
Perspectives and challenges in multilayer ceramic capacitors for next generation electronics
Authors: Hong Kootak , Lee Tae Hyung , Suh Jun Min , Yoon Seok-Hyun , Jang Ho Won
Published: July 2019

This review highlights the critical issues and recent advances in developing highly volumetric-efficient and high capacitance MLCCs from the viewpoint of designing dielectric materials.
Robust H∞ state feedback control for handling stability of intelligent vehicles on a novel all‐wheel independent steering mode
Authors: Zhang Naisi , Ni Jun , Hu Jibin
Published: July 2019

We propose an H∞ dynamics controller for an all‐wheel independent steering. A norm‐bounded method is used to describe the uncertainties in the system. A new reference model aimed at minimising the yaw rate and making the sideslip angle remain the same as the target sideslip angle is proposed; this will help especially when a vehicle changes lanes. Simulation and experimental results indicate that the controller can help improve the handling stability and correct directional problems when the vehicle's direction is changed by the steering angle.
Vision‐based road slope estimation methods using road lines or local features from instant images
Authors: Ustunel Eser , Masazade Engin
Published: July 2019

In this study, the authors study lateral and longitudinal road slope estimation, which are important parameters to control a vehicle laterally in lane‐keeping assistance and longitudinally in adaptive cruise control, respectively. They present three methods estimating road slopes from instant road images obtained from a front monocular camera. In the first geometry‐based (GB) method, they obtain the slope estimates using 2D road lines derived from 3D road line and pin‐hole camera models. In the second local features‐based (LFB) method, they use the SIFT local features between two consecutive image pairs. In the first two methods, they derive computationally simple novel analytic expressions for the road slope estimates. As a third solution in covariance based (CB) method, they consider supervised learning where they use 2D road lines as features to train their algorithm. GB and CB methods rely on road lines and provide in advance estimations that enable proactive driving, whereas LFB uses the entire image and performs estimation when the road slope actually changes. They use multi‐layer perceptron learning method as a benchmark in their tests. They compare the estimation performance, system requirements, and applicable conditions of the proposed methods under controlled and uncontrolled test environments.
Fault‐tolerant control of a smart PV‐grid hybrid system
Authors: Tiar Mourad , Betka Achour , Drid Said , Abdeddaim Sabrina , Sellali Mehdi , Medjmadj Slimane
Published: July 2019

This study deals with a fault‐tolerant control of a smart PV‐grid plant. The small scale system is dedicated to a stationary alternative current load and it consists of a photovoltaic module, supported by a single‐phase grid. To ensure a smart permutation between the two proposed operation modes, a fuzzy logic‐based power management algorithm is designed and implemented. In case of a sub‐system failure, a fault‐tolerant control technique is adopted to maintain the service continuity. In this study, two scenarios are proposed. The first concerns a load current sensor failure, where a material redundancy is adopted through the use of two observers, selected via a voting algorithm. The second deals to sense the system ability to maintain the service continuity in the worst case, where a grid black‐out (grid‐off) is planned. In this scenario, an additional functioning mode is added to reconfigure the control strategy. To prove the effectiveness of the proposed algorithms, the obtained experimental results with a given load profile are presented and commented.
Anesthetic Considerations in Cardiac Patients Undergoing Neurosurgery
Authors: Bhatt Rashmi , Khanna Puneet
Published: July 2019

Elective and emergency neurosurgical procedures pose considerable risk in patients with cardiac disease. As the incidence of cardiac disease has increased in the general population over the past few decades, it is imperative to familiarize oneself with the challenges posed and the recommended management guidelines. The eventual outcome is significantly altered by the nature and severity of the underlying cardiac condition, as is the anesthetic management. A well-optimized cardiac condition can reduce morbidity and mortality considerably, which, however, may not be possible in neurosurgical emergencies. This review aims to look at various pathophysiological implications of cardiac disease, against the background of anesthetic management of neurosurgery. The discussion includes assessment and stratification of risk, appropriate investigations indicated, and the plan of anesthetic management. Even though no specific guidelines have been formulated, the discussion is largely to derive from the guidelines for patients with cardiac disease undergoing noncardiac surgery.
Extracranial Complications of Traumatic Brain Injury: Pathophysiology—A Review
Authors: Gundappa Parameswara
Published: July 2019

Moderate to severe traumatic brain injury is often associated with several extracranial organ complications, which increase the morbidity and mortality. Respiratory complications such as acute lung injury, pneumonia, and acute respiratory distress syndrome (ARDS) occur most commonly, but neurogenic pulmonary edema can be life threatening. Cardiovascular complications occur frequently. However, arrhythmia, cardiogenic shock, and neurogenic stunned myocardium, though occur infrequently, can be life threatening. Coagulation abnormalities and sepsis constitute serious complications that may result in multiorgan failure. These constitute independent risk factors for mortality. Endocrine abnormalities, gastrointestinal disruptions, and other complications occur less commonly. These extracranial complications develop as a result of altered neurogenic immune response, both central and peripheral responses. Brain tissue injury releases both proinflammatory mediators taking part in tissue reparative process and anti-inflammatory cytokines that propagate inflammation. In addition, release of massive amount of catecholamines after head injury results in proliferation of myeloid depressor cells in the circulation, release of reactive oxygen species, and release of immature neutrophils into the circulation. These anti-inflammatory mediators by complex mechanisms inhibit and decrease the number of T cells and cause apoptosis. This results in decreased production and release of cytokines and reduced lymphocyte activated killer cell cytotoxicity, resulting in impaired hypersensitivity reaction. Finally, the complex interplay of various factors leads to suppression of peripheral immune response and susceptibility for infection and sepsis, and causes extracranial organ system failure with increased morbidity and mortality.
Neurogenic Stunned Myocardium in Two Children with Neurological Injury
Authors: Díaz Ruiz Laura , Durán Lorenzo Iria , Ordoñez Sáez Olga
Published: July 2019

Neurogenic stunned myocardium is described as sudden and reversible cardiac dysfunction induced by an acute neurological event. This phenomenon has not been thoroughly investigated in infants, and is probably underdiagnosed. Here, we report the cases of two infants with neurogenic stunned myocardium in whom the clinical suspicion was relevant, with a brief discussion of this condition.
Does Size Matter: Evaluating the Difference between Right and Left Internal Mammary Veins in Free Flap Breast Reconstruction
Authors: Mauch Jaclyn T. , Rhemtulla Irfan A. , Katzel Evan B. , Hernandez J. Andres , Broach Robyn B. , Serletti Joseph M.
Published: July 2019

Background Venous congestion in breast free flap reconstruction continues to be a major reason for flap compromise requiring reoperative exploration and possible flap failure. We aim to investigate whether size of the internal mammary vein (IMV) (1) varies between the left and right sides, (2) changes with certain patient demographics or preoperative factors, and (3) correlates with postoperative complications.

Methods We performed a retrospective cohort study examining all patients undergoing free flap breast reconstruction from September 2005 to March 2016 using internal mammary recipient veins. Venous coupler size was used as a surrogate measure of IMV diameter. Preoperative patient characteristics and factors were collected. Postoperative outcomes assessed included thrombosis, flap loss, fat necrosis, and mastectomy flap necrosis. Multivariate analyses were performed to evaluate if preoperative factors affected IMV diameter and to determine if coupler size and flap side were independent risk factors for postoperative complications.

Results We examined 372 patients with a total of 561 flaps. One hundred eighty-nine patients received bilateral flaps with the IMV as a recipient. The right IMV (n = 286, average = 2.97 mm, standard deviation [SD] = 0.41) was significantly larger than the left (n = 275, average = 2.89, SD = 0.35, p = 0.008). Preoperative factors and postoperative complications were not statistically different between the left and right cohorts. The multivariable linear regression model with coupler size as the dependent variable found older age trended toward a larger coupler size but this was not significant (p = 0.05). In multilinear regression analysis, the postoperative outcomes did not have significant covariates.

Conclusion We found that IMV size significantly differs between the right and the left sides. However, incidence of postoperative complications was not significantly different between the left and right sides, and the multivariate analyses did not identify flap side as an independent risk factor for adverse outcomes. Prospective studies evaluating actual IMV diameter and associated complications may potentially elucidate clinical significance.
Effect of Static Cold Storage on Skeletal Muscle after Vascularized Composite Tissue Allotransplantation
Authors: Gok Emre , Kubiak Carrie A. , Guy Erin , Kemp Stephen W.P. , Ozer Kagan
Published: July 2019

Background Prolonged cold ischemia associated with static cold storage (SCS) results in higher incidence of acute and chronic allograft rejection in solid organ transplantations. Deleterious effects of SCS on vascularized composite tissue allograft were studied with limited data on muscle structure and function. The aim of this study is to evaluate the long-term impact of SCS on muscle metabolism, structure, and force generation using a syngeneic rat hindlimb transplantation model.

Methods Sixty-five male Lewis rats (250 ± 25 g) were distributed into five groups, including naive control, sciatic nerve denervation/repair, immediate transplantation, transplantation following static warm storage for 6 hours at room temperature, and transplantation following SCS for 6 hours at 4°C. Sciatic nerves were repaired in all transplantations. Muscle samples were taken for histology and metabolomics analysis following electromyography and muscle force measurements at 12 weeks after transplantation.

Results All cold-preserved limbs remained viable at 12 weeks, whereas animals receiving limbs preserved in room temperature had no survivors. The SCS transplantation group showed a 73% injury score, significantly higher than groups receiving immediate transplants without cold preservation (50%, p < 0.05). A significant decline in muscle contractile force was also demonstrated in comparison to the immediate transplantation group (p < 0.05). In the SCS group, muscle energy reserves remained relatively well preserved in surviving fibers.

Conclusion SCS extends allograft survival but fails to preserve muscle structure and force.
Congenital Rubella Syndrome: Clinical and Imaging Features
Authors: Ghanaat Mahyar , Soleiman Aron
Published: July 2019

Congenital rubella syndrome is rare in high-income countries. A 19-year-old pregnant female, who recently immigrated to the United States, presented to clinic for prenatal care at 21 weeks of gestational age. Prenatal ultrasound demonstrated twin gestations with a cleft lip present in twin B. Ultrasound at 36 weeks of gestational age demonstrated fetal demise in twin A and growth restriction in twin B. Twin B was delivered via emergency C-section due to fetal distress. The viable neonate demonstrated multiple abnormalities including microcephaly, patent ductus arteriosus, atrial septal defect, cardiomegaly, pulmonary edema, congenital polar cataracts, congenital adrenal hyperplasia, thyroiditis, cleft palate/lip, and abnormal hearing.
Using the video head impulse test in healthy Danish adolescents
Authors: Lissner Victor Mathias Hornshøj , Devantier Louise , Ovesen Therese
Published: July 2019

Purpose:

Adolescents presenting with vertigo can be a diagnostic challenge. Video head impulse testing (vHIT) offers examination of the semicircular canals in adolescents with few drawbacks. It quantifies the vestibular ocular reflex as a gain-value. However, there is no standardized method to calculate the gain-value. The aim of this article is to define which gain measure is the most optimal and whether the test is clinically tolerable and feasible in diagnostics of adolescents.

Methods:

Thrity-three Danish healthy adolescents aged 13–16 years, had their lateral semicircular canals examined with vHIT. Gain calculations were obtained at 40, 60, 80, 0–100 ms and as a regression gain.

Results:

Mean gain values for the right side were: 40 ms: 1.04, 60 ms: 0.98, 80 ms: 0.93, 0–100 ms: 1.08 and regression: 1.04. For the left-side gain values were 40 ms: 0.96, 60 ms: 0.96, 80 ms: 0.98, 0–100 ms: 1.00 and regression: 1.01. T-tests on 60 ms, 0–100 ms and regressions gain showed that 60 ms differed significantly from 0 to100 ms and regression gain. No complaints of discomfort were reported by any of the test subjects.

Conclusions:

vHIT proved to be a highly applicable procedure with many advantages, but also some potential pitfalls. In healthy adolescents, 0–100 ms and regression gain produce the most reliable results.
RETRACTED: Regulating phase change behavior and surface characteristics of Sn15Sb85 thin film by oxygen doping
Authors: Hu Yifeng , You Haipeng , Chou Qingqian , Lai Tianshu
Published: July 2019

In this paper, oxygen doped Sn15Sb85 thin films were proposed to reduce the power consumption for phase change memory (PCM) application. Compared with Sn15Sb85, oxygen doped Sn15Sb85 thin film had higher crystallization temperature (168 °C–255 °C) and broader energy band gap (1.23–1.55 eV). X-ray diffraction patterns and transmission electron microscope showed that the crystallization of thin film was suppressed and grains became smaller when oxygen was added. After oxygen doping, the surface roughness decreased from 13.6 to 2.5 nm. Antimony oxide formed to enhance the thermal stability. In comparison to Ge2Sb2Te5, oxygen doped Sn15Sb85 had an ultra-fast phase transition speed (3.9 ns) confirmed by laser picosecond technology. The result of differential scanning calorimetry revealed that oxygen doped Sn15Sb85 had a lower melting temperature (494 °C). PCM cells based on the oxygen doped Sn15Sb85 thin film were fabricated to evaluate the electrical characteristics as well. The results indicated that the oxygen doped Sn15Sb85 thin film had great potentiality in PCM application.
The Role of Nonfarm Influences in Ricardian Estimates of Climate Change Impacts on US Agriculture
Authors: Ortiz‐Bobea Ariel
Published: July 2019

The Ricardian approach is a popular hedonic method for analyzing climate change impacts on agriculture. The approach typically relies on a cross‐sectional regression of farmland asset prices on fixed climate variables, making it particularly vulnerable to omitted variables. I conduct a long‐spanning Ricardian analysis of farmland prices in the eastern United States (1950–2012) and find a convergence of evidence indicating that large estimates of climate change damages for recent cross‐sections (>1970s), also found in the literature, can be explained by the growing influence of omitted factors extraneous to the agricultural sector. I propose and evaluate a simple strategy to circumvent such nonfarm influences in the form of a Ricardian model based on cash rents (2009–2016), which better reflect agricultural profitability and do not capitalize expected land use changes. The new damage estimates on nonirrigated cropland and pasture rents are more optimistic and cannot be distinguished from zero. However, estimates remain imprecise under extreme climate change scenarios pointing to a cautionary long‐term outlook for United States agriculture. The findings are robust to multiple checks and alternative explanations.
Correlation between non-invasive myocardial work indices and main parameters of systolic and diastolic function: results from the EACVI NORRE study
Authors: Manganaro Roberta , Marchetta Stella , Dulgheru Raluca , Sugimoto Tadafumi , Tsugu Toshimitsu , Ilardi Federica , Cicenia Marianna , Ancion Arnaud , Postolache Adriana , Martinez Christophe , Kacharava George , Athanassopoulos George D , Barone Daniele , Baroni Monica , Cardim Nuno , Hagendorff Andreas , Hristova Krasimira , Lopez Teresa , de la Morena Gonzalo , Popescu Bogdan A , Penicka Martin , Ozyigit Tolga , Rodrigo Carbonero Jose David , van de Veire Nico , Von Bardeleben Ralph Stephan , Vinereanu Dragos , Zamorano Jose Luis , Rosca Monica , Calin Andreea , Moonen Marie , Magne Julien , Cosyns Bernard , Galli Elena , Donal Erwan , Carerj Scipione , Zito Concetta , Santoro Ciro , Galderisi Maurizio , Badano Luigi P , Lang Roberto M , Lancellotti Patrizio
Published: July 2019

Aims

The present study sought to evaluate the correlation between indices of non-invasive myocardial work (MW) and left ventricle (LV) size, traditional and advanced parameters of LV systolic and diastolic function by 2D echocardiography (2DE).

Methods and results

A total of 226 (85 men, mean age: 45 ± 13 years) healthy subjects were enrolled at 22 collaborating institutions of the Normal Reference Ranges for Echocardiography (NORRE) study. Global work index (GWI), global constructive work (GCW), global work waste (GWW), and global work efficiency (GWE) were estimated from LV pressure-strain loops using custom software. Peak LV pressure was estimated non-invasively from brachial artery cuff pressure. LV size, parameters of systolic and diastolic function and ventricular-arterial coupling were measured by echocardiography. As advanced indices of myocardial performance, global longitudinal strain (GLS), global circumferential strain (GCS), and global radial strain (GRS) were obtained. On multivariable analysis, GWI was significantly correlated with GLS (standardized beta-coefficient = −0.23, P < 0.001), ejection fraction (EF) (standardized beta-coefficient = 0.15, P = 0.02), systolic blood pressure (SBP) (standardized beta-coefficient = 0.56, P < 0.001) and GRS (standardized beta-coefficient = 0.19, P = 0.004), while GCW was correlated with GLS (standardized beta-coefficient = −0.55, P < 0.001), SBP (standardized beta-coefficient = 0.71, P < 0.001), GRS (standardized beta-coefficient = 0.11, P = 0.02), and GCS (standardized beta-coefficient = −0.10, P = 0.01). GWE was directly correlated with EF and inversely correlated with Tei index (standardized beta-coefficient = 0.18, P = 0.009 and standardized beta-coefficient = −0.20, P = 0.004, respectively), the opposite occurred for GWW (standardized beta-coefficient =−−0.14, P = 0.03 and standardized beta-coefficient = 0.17, P = 0.01, respectively).

Conclusion

The non-invasive MW indices show a good correlation with traditional 2DE parameters of myocardial systolic function and myocardial strain.
Radiofrequency catheter ablation for inappropriate sinus tachycardia in a patient with systemic lupus erythematosus: a case report
Authors: Yoshizawa Reisuke , Komatsu Takashi , Kojima Kaori , Owada Shingen
Published: July 2019

Background

Systemic lupus erythematosus (SLE) is known to cause inappropriate sinus tachycardia (IST). However, there is limited evidence available with regard to the treatment of IST in this setting. In this article, we report a case of drug refractory IST in a patient with SLE treated with radiofrequency catheter ablation (RFCA) using a non-contact mapping system.

Case summary

A 33-year-old woman had been diagnosed with SLE in 2001. She presented with complaints of persistent palpitations for 1 month and persistent sinus tachycardia. She underwent RFCA using a non-contact mapping system for drug refractory IST. The voltage and activation maps did not show obvious differences in the earliest activation site at heart rates (HRs) 90–150 b.p.m. In contrast, the areas of breakout sites were clearly distinguished between those from the normal P-wave zones at HR <140 b.p.m. and those from higher rate sites at HR >140 b.p.m. Radiofrequency catheter ablation was performed in those areas as the target for ablation. Thereafter, the symptoms steadily disappeared and the maximum HR—using 24-h Holter monitoring—decreased from 156 to 120 b.p.m.

Discussion

Radiofrequency catheter ablation using a non-contact mapping system was applied to the treatment of drug refractory IST in a patient with SLE. Of note, IST in such patients may be left untreated. This approach may be considered as a first-line therapy option for drug refractory IST in patients with SLE.
Bioprosthetic tricuspid valve stenosis: a case series
Authors: Hirata Kazuhito , Tengan Toshiho , Wake Minoru , Takahashi Takanori , Ishimine Toru , Yasumoto Hiroshi , Nakasu Akio , Mototake Hidemitsu
Published: July 2019

Background

Bioprosthetic tricuspid valve stenosis is a late sequela of tricuspid valve replacement (TVR); however, detailed information regarding its clinical picture is lacking.

Case summary

Thirty-one patients with bioprosthetic TVR (mean age: 60.5 ± 16.6 years, male/female: 11/20) were followed-up for 79.5 ± 49.1 months (14–188 months). Eleven patients developed bioprosthetic tricuspid valve stenosis (mean tricuspid gradient >5 mmHg) at a median interval of 96 months (interquartile range: 61–114 months). The mean tricuspid gradient at the time of tricuspid valve stenosis diagnosis was 10.9 ± 3.9 mmHg. Although the mid-term tricuspid valve stenosis-free survival was favourable (92.4% at 60 and 78.7% at 84 months), it had declined steeply to 31.5% by 120 months. Ten out of 11 tricuspid valve stenosis patients showed signs of right heart failure (RHF) as manifested by oedema and elevated jugular venous pressure, requiring moderate-to-high doses of diuretics. Diastolic rumble was audible in 10 patients. Five of the 11 tricuspid valve stenosis patients required redo TVR as a result of refractory RHF. Examination of the five excised bioprostheses showed pannus in four, fusion of the commissure in three, native valve attachment in two, and sclerosis in one. Detailed clinical pictures and pathology of the explanted valves in three cases that underwent surgery are presented in this case series.

Discussion

Bioprosthetic tricuspid valve stenosis is not uncommon after 8 years. Tricuspid valve replacement performed at the second surgery was associated with a higher incidence of bioprosthetic tricuspid valve stenosis.
Percutaneous extraction of a leadless Micra pacemaker after dislocation: a case report
Authors: Fichtner Stephanie , Estner Heidi L , Näbauer Michael , Hausleiter Jörg
Published: July 2019

Background 

Leadless pacemaker implantation rates are increasing worldwide. Until now leadless pacemaker dislocation and extraction has been rarely reported.

Case summary 

An 83-year-old patient with cardiac amyloidosis, chronic atrial fibrillation, and complete heart block was implanted with a leadless pacemaker (Micra, Medtronic). On the day after implantation, the device showed an exit block and on cardiac echocardiography and cardiac computer tomography, a device dislocation could be detected. During the day, the device moved at least three times between the tricuspid valve and the right ventricular apex. Each time causing non-sustained ventricular tachycardia. At the next day device extraction was scheduled. After 189 minutes of procedure time, it was possible to retrieve the device with the help of two steerable introducers (Agilis) and two snare catheters.

Discussion 

Implantable transcatheter leadless pacemakers can be implanted safely most of the time. However, in rare cases device dislocations may occur. Device extraction is possible, but is described as challenging in most published cases
Case report of a sub-occluding thrombus in thoracic aorta: what is the origin?
Authors: Campana Federica , Nardin Matteo , Coppini Anna , Muiesan Maria Lorenza
Published: July 2019

Background

Aortic thrombosis represents a consequence of atherosclerotic disease. In few cases, it can be secondary to large vessel or infective vasculitis. More rarely, aortic thrombosis is the manifestation of a primary malignant neoplasm of the aortic wall. Aortic angiosarcoma is a rare tumour, its clinical presentation is often non-specific and associated signs and symptoms may vary greatly. An early diagnosis is difficult to reach and the presence of metastatic disease is not uncommon at the time of diagnosis. The prognosis is poor overall.

Case summary

We report the case of a female patient who presented to her GP because of fatigue, hyporexia, weight-loss, and anaemia. An ultrasound of the abdomen showed two small pancreatic lesions, confirmed and described as benign cystic pancreatic lesions on computed tomography (CT) imaging; an incidental thrombus in the superior mesenteric artery was also found on CT imaging. The thoracic CT identified a large thrombotic lesion in the descending thoracic aorta with significant narrowing of the aortic lumen and confirmed the presence of an osteolytic bone lesion on the VIII right rib, in the absence of atherosclerotic disease. Signs of increased metabolic activity in the aortic lumen and in the VIII posterior right rib were shown at a subsequent positron emission tomography. A CT-guided biopsy of the bone lesion was performed and at histology the diagnosis of metastatic angiosarcoma of the aortic wall was made.

Discussion

Aortic angiosarcoma is a rare cause of aortic thrombosis, to be taken into consideration in a patient with thrombotic lesions of the aorta in the absence of atherosclerotic disease. The differential diagnosis is difficult because of clinical presentation and radiological features similar to those of inflammatory aortic disease. In our case, the final diagnosis of angiosarcoma was made only by a biopsy of a bone metastatic lesion.
An unusual case of stent thrombosis: a case report
Authors: Rahman Atifur , Wong Sophia
Published: July 2019

Background 

Stent thrombosis is a serious and potentially life-threatening complication of percutaneous coronary intervention. It often presents dramatically, typically resulting in ST-elevation myocardial infarction which is associated with a high mortality rate. Premature discontinuation of antiplatelet therapy in the initial 30 days after stenting is arguably the most important predictor of stent thrombosis. In some cases, discontinuation of therapy is unintentional, such as in patients with short-bowel length or malabsorption syndromes.

Case summary 

A 70-year-old man presented to our hospital with stent thrombosis due to non-absorption of antiplatelet agents, 3 days after an elective percutaneous intervention to the right coronary artery. The patient, who had had a laparoscopic high anterior resection due to previous colorectal cancer, had noticed tablets passing whole into his colostomy bag. Repeat balloon angioplasty and stenting were performed and the patient received further antiplatelet therapy in a crushed form.

Discussion 

Drug absorption in the gastrointestinal tract is altered when a significant length of the gut has been resected. Reduced intestinal luminal transit time and insufficient contact time with intestinal mucosa leads to reduced bioavailability of drugs and increased risk of stent thrombosis. The aetiology of stent thrombosis can be investigated with intravascular imaging techniques and platelet function testing. Management includes using different drug formulations and doses and monitoring the outcomes of therapy. In some cases, it may also be appropriate to involve a gastroenterology team, preferably in the multidisciplinary environment of an intestinal rehabilitation centre.
The left atrial appendage in humans: structure, physiology, and pathogenesis
Authors: Karim Nabeela , Ho Siew Yen , Nicol Edward , Li Wei , Zemrak Filip , Markides Vias , Reddy Vivek , Wong Tom
Published: July 2019

For many years, the left atrial appendage (LAA) was considered a dormant embryological remnant; however, it is a structurally complex and functional organ that contributes to cardiac haemodynamic changes and volume homeostasis through both its contractile properties and neurohormonal peptide secretion. When dysfunctional, the LAA contributes to thrombogenesis and subsequent increased predisposition to cardioembolic events. Consequently, the LAA has gained much attention as a therapeutic target to lower this risk. In addition, attention has focused on the LAA in its role as an electrical trigger for atrial tachycardia and atrial fibrillation with ablation of the LAA to achieve electrical isolation showing promising results in the maintenance of sinus rhythm. This in-depth review explores the structure, physiology and pathophysiology of the LAA, as well as LAA intervention and their sequelae.
Reconstruction of the disturbance history of a temperate coniferous forest through stand-level analysis of airborne LiDAR data
Authors: Sanchez-Lopez Nuria , Boschetti Luigi , Hudak Andrew T
Published: July 2019

Spatially explicit information about stand-level Time Since the last stand-replacing Disturbance (TSD) is fundamental for modelling many forest ecosystem processes, but most of the current satellite remote sensing mapping approaches are based on change detection and time series analysis, and can detect only disturbances that have occurred since the start of the optical satellite data record. The spatial legacy of stand-replacing disturbances can however persist on the landscape for several decades to centuries, in the form of distinct horizontal and vertical stand structure features. We propose a new approach to reconstruct the long-term disturbance history of a forest, estimating TSD through stand-level analysis of LiDAR data, which are highly sensitive to the three-dimensional forest canopy structure. The study area is in the Nez Perce-Clearwater National Forest in north-central Idaho, where airborne LiDAR covering about 52,000 ha and ancillary TSD reference data for a period of more than 140 years were available. The root mean square difference (RSMD) between predicted and reference TSD was 17.5 years with a BIAS of 0.8 years; and on 72.8% of the stands the predicted TSD was less than 10 years apart from the reference TSD (78.2% of the stands when considering only disturbances occurred in the last 100 years). The results demonstrate that airborne LiDAR-derived data have enough explanatory power to reconstruct the long-term, stand-replacing disturbance history of temperate forested areas at regional scales.
Joint effect of pre-operative anemia and perioperative blood transfusion on outcomes of colon-cancer patients undergoing colectomy
Authors: Liu Zheng , Luo Jia-Jun , Pei Kevin Y , Khan Sajid A , Wang Xiao-Xu , Zhao Zhi-Xun , Yang Ming , Johnson Caroline H , Wang Xi-Shan , Zhang Yawei
Published: July 2019

Background

Both pre-operative anemia and perioperative (intra- and/or post-operative) blood transfusion have been reported to increase post-operative complications in patients with colon cancer undergoing colectomy. However, their joint effect has not been investigated. The purpose of this study was to evaluate the joint effect of pre-operative anemia and perioperative blood transfusion on the post-operative outcome of colon-cancer patients after colectomy.

Methods

We identified patients from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database 2006–2016 who underwent colectomy for colon cancer. Multivariate logistic regression analysis was employed to assess the independent and joint effects of anemia and blood transfusion on patient outcomes.

Results

A total of 35,863 patients—18,936 (52.8%) with left-side colon cancer (LCC) and 16,927 (47.2%) with right-side colon cancer (RCC)—were identified. RCC patients were more likely to have mild anemia (62.7%) and severe anemia (2.9%) than LCC patients (40.2% mild anemia and 1.4% severe anemia). A total of 2,661 (7.4%) of all patients (1,079 [5.7%] with LCC and 1,582 [9.3%] with RCC) received a perioperative blood transfusion. Overall, the occurrence rates of complications were comparable between LCC and RCC patients (odds ratio [OR] = 1.01; 95% confidence interval [CI] = 0.95–1.07; P = 0.750). There were significant joint effects of anemia and transfusion on complications and the 30-day death rate (P for interaction: 0.010). Patients without anemia who received a transfusion had a higher risk of any complications (LCC, OR = 3.51; 95% CI = 2.55–4.85; P < 0.001; RCC, OR = 3.74; 95% CI = 2.50–5.59; P < 0.001), minor complications (LCC, OR = 2.54; 95% CI = 1.63–3.97; P < 0.001; RCC, OR = 2.27; 95% CI = 1.24–4.15; P = 0.008), and major complications (LCC, OR = 5.31; 95% CI = 3.68–7.64; P < 0.001; RCC, OR = 5.64; 95% CI = 3.61–8.79; P < 0.001), and had an increased 30-day death rate (LCC, OR = 6.97; 95% CI = 3.07–15.80; P < 0.001; RCC, OR = 4.91; 95% CI = 1.88–12.85; P = 0.001) than patients without anemia who did not receive a transfusion.

Conclusions

Pre-operative anemia and perioperative transfusion are associated with an increased risk of post-operative complications and increased death rate in colon-cancer patients undergoing colectomy.
Outcomes of mitral valve repair in acute native mitral valve infective endocarditis
Authors: El Gabry Mohamed , Haidari Zaki , Mourad Fanar , Nowak Janine , Tsagakis Konstantinos , Thielmann Matthias , Wendt Daniel , Jakob Heinz , Shehada Sharaf-Eldin
Published: July 2019

OBJECTIVES

Mitral valve repair (MVR) is considered the treatment of choice for mitral valve (MV) regurgitation. However, MVR in acute native MV infective endocarditis is technically challenging and not commonly performed. Our goal was to report our outcomes of MVR in acute native MV infective endocarditis.

METHODS

Between January 2016 and December 2017, 35 patients presenting with acute native MV infective endocarditis underwent MVR. Primary end points were successful MVR and freedom from recurrent endocarditis. Secondary end point was the postoperative incidence of major adverse events.

RESULTS

The mean age was 58 ± 13 years (74% men) and the median logistic EuroSCORE was 17.1%. Twenty patients underwent isolated MVR; the other 15 patients underwent concomitant procedures. MVR was performed with removal of the vegetation (vegectomy), limited resection of the infected tissue, direct closure of the defect, besides annuloplasty in all patients. Mean intensive care and hospital stays were 5 and 17 days, respectively. All-cause mortality was 11% (4/35) at 30 days and a total of 23% (8/35) within a follow-up period of 10 ± 7.7 months. Endocarditis recurred in 2 patients 15 and 8 months after surgery, respectively. Both underwent successful MV re-repair. Follow-up echocardiography indicated none-to-trace, mild or moderate regurgitation in 15, 10 and 2 patients, respectively.

CONCLUSIONS

Although MVR in acute native MV infective endocarditis is a complex procedure, it offers a treatment option for such patients with acceptable short-term results. Limited resection in addition to annuloplasty is our preferred method of repair. Nevertheless, long-term results in a larger cohort are still mandatory.
Intimal sarcoma in an ascending aortic Dacron graft mimicking a thrombus
Authors: Natsume Kayoko , Shiiya Norihiko , Tsuchida Takashi , Nagakura Yuka
Published: July 2019

Although aortic sarcomas are extremely rare, they may arise in association with a Dacron graft. Here, we report a case of an intimal sarcoma in an ascending aortic Dacron graft implanted 17 years earlier. The patient presented with multiple cerebral infarctions; clinically, a thrombus was found to cause the embolic stroke. He successfully underwent re-replacement of the ascending aorta. Although the initial postoperative histopathological diagnosis was a thrombus, he died of multiple metastases of the malignant tumour after 5 months of the surgery. A histopathological re-evaluation of the explant using immunohistochemistry revealed that the mass was an intimal sarcoma.