bluuebunny/crossref_metadata_2025 huggingface dataset:
MITF and UV responses in skin: From pigmentation to addiction
Authors: Nguyen Nhu T. , Fisher David E.
Published: July 2018

Ultraviolet radiation (UVR) has numerous effects on skin, including DNA damage, tanning, vitamin D synthesis, carcinogenesis, and immunomodulation. Keratinocytes containing damaged DNA secrete both α‐melanocyte‐stimulating hormone (α‐MSH), which stimulates pigment production by melanocytes, and the opioid β‐endorphin, which can trigger addiction‐like responses to UVR. The pigmentation (tanning) response is an adaptation that provides some delayed protection against further DNA damage and carcinogenesis, while the opioid response may be an evolutionary adaptation for promoting sun‐seeking behavior to prevent vitamin D deficiency. Here, we review the pigmentation response to UVR, driven by melanocytic microphthalmia‐associated transcription factor (MITF), and evidence for UVR‐induced melanomagenesis and addiction. We also discuss potential applications of a novel approach to generate protective pigmentation in the absence of UVR (sunless tanning) using a topical small‐molecule inhibitor of the salt‐inducible kinase (SIK) family.
Orofacial granulomatosis and erythema multiforme in an adolescent with Crohn's disease
Authors: Georgesen Corey , Huang Jing , Avarbock Andrew , Harp Joanna , Magro Cynthia
Published: July 2018

The cutaneous manifestations of Crohn's disease are myriad. A 15‐year‐old girl presented with recurrent lip swelling and eventual development of diarrhea and targetoid macules on the palms, feet, and back. She was finally diagnosed with Crohn's disease in the setting of a clinical presentation and histopathology consistent with orofacial granulomatosis and erythema multiforme. We review the literature and summarize reported occurrences of these cutaneous diseases in children with Crohn's disease.
Congenital fibroblastic connective tissue nevi: Unusual and misleading presentations in three infantile cases
Authors: Bouaoud Jebrane , Fraitag Sylvie , Soupre Veronique , Mitrofanoff Marc , Boccara Olivia , Galliot Christelle , Bodemer Christine , Picard Arnaud , Khonsari Roman H.
Published: July 2018

Background

Fibroblastic connective tissue nevi (FCTN) are benign skin conditions characterized by bland spindle cells infiltrating the reticular dermis and the upper subcutis with preservation of adnexal structures. A subset of FCTN expresses CD34, which may cause difficulties in the differential diagnosis, in particular with dermatofibrosarcoma (DFSP). We aim to study clinical and histological main features of congenital FCTN to better understand their heterogeneity.

Methods

We present 3 cases of congenital FCTN with misleading pseudo‐tumoral presentations and compare them with published cases in literature. We provide a diagnostic algorithm for congenital neonatal connective tissue tumors.

Results

Clinically, FCTN mostly present as well‐limited and nontender plaques or nodules mainly located in the neck and face areas or in the trunk. Histologically, FCTN are composed of irregularly distributed fascicles of bland spindled cells and are defined by a list of fundamental features: (i) no atypia, pleomorphism, or mitotic activity; (ii) skin appendages entrapped but unaffected; (iii) no evidence for malignancy. In most cases CD34 is positive, but in some cases, cells can express SMA or are even CD34− and SMA−.

Conclusion

The initial presentation and natural history of FCTN fit better with a neoplasm than with a hamartoma. Thus, we suggest replacing the term “nevus” with tumor and considering fibroblastic connective tissue tumor (FCTT) as the right denomination of this clinico‐pathological entity. FCTTs are difficult to diagnose due to their clinical heterogeneity. Clinical and histological malignant and benign differential diagnoses are discussed.
Framing Effects under Different Uses of Performance Information: An Experimental Study on Public Managers
Authors: Belardinelli Paolo , Bellé Nicola , Sicilia Mariafrancesca , Steccolini Ileana
Published: July 2018

Combining insights from public administration, accounting, and psychology, this article explores the microprocesses by which public managers use performance information, investigating whether the type of performance information use and the request to justify decisions affect the way in which information is processed. The study draws on data from a series of artifactual survey experiments with Italian municipal executives. Findings show that managers process information differently under ex post rather than ex ante performance information uses. More specifically, managers are more likely to be subject to framing bias under ex post than under ex ante uses of performance information. This interaction seems to be robust when subjects are asked to provide justification for their decisions.
Optimal Treatment Allocations in Space and Time for On-Line Control of an Emerging Infectious Disease
Authors: Laber Eric B. , Meyer Nick J. , Reich Brian J. , Pacifici Krishna , Collazo Jaime A. , Drake John M.
Published: July 2018

A key component in controlling the spread of an epidemic is deciding where, when and to whom to apply an intervention. We develop a framework for using data to inform these decisions in realtime. We formalize a treatment allocation strategy as a sequence of functions, one per treatment period, that map up-to-date information on the spread of an infectious disease to a subset of locations where treatment should be allocated. An optimal allocation strategy optimizes some cumulative outcome, e.g. the number of uninfected locations, the geographic footprint of the disease or the cost of the epidemic. Estimation of an optimal allocation strategy for an emerging infectious disease is challenging because spatial proximity induces interference between locations, the number of possible allocations is exponential in the number of locations, and because disease dynamics and intervention effectiveness are unknown at outbreak. We derive a Bayesian on-line estimator of the optimal allocation strategy that combines simulation–optimization with Thompson sampling. The estimator proposed performs favourably in simulation experiments. This work is motivated by and illustrated using data on the spread of white nose syndrome, which is a highly fatal infectious disease devastating bat populations in North America.
Longitudinal associations between weather, season, and mode of commuting to school among Spanish youths
Authors: Herrador‐Colmenero Manuel , Harrison Flo , Villa‐González Emilio , Rodríguez‐López Carlos , Ortega Francisco B. , Ruiz Jonatan R. , Jones Andy P. , Chillón Palma
Published: July 2018

Aim

To study the associations of weather conditions with the travel mode choice for commuting to and from school.

Methods

A total of 6979 Spanish youths aged 7 to 18 years old (80% adolescents aged 12‐18 years old, 51% male) completed a 5‐day survey of mode of commuting to school in autumn, winter, and spring. Weather data from the nearest weather station to each school were registered. We used Google Maps™ to calculate the distance from home to school. Multilevel logistic regression models were used to estimate odds of active travel based on weather and season.

Results

We analyzed a total of 163 846 discrete journeys. In winter, children (aged 7 to 11 years old) were less likely to choose an active mode of commuting to school (OR: 0.72, 95% CI: 0.59‐0.89, P = 0.003). In spring, adolescents were more likely to choose an active mode of commuting to school (OR: 1.43, 95% CI: 1.19‐1.73, P < 0.001). With higher mean temperatures, adolescents were more likely to choose an active mode of commuting from school (OR: 1.02, 95% CI: 1.00‐1.04, P = 0.029).

Conclusion

Certain weather conditions seem to influence the travel mode choice for commuting to and from school in youth, including season and temperature.
States, elites, and inequality in Latin America
Authors: López Matias
Published: July 2018

In this article, I review the literature on elites and inequality in Latin America with a focus on the emergence of uneven state structures and how they came to foster the needs of elites for protection. States in Latin America are traditionally thought of as facilitating processes of top‐down modernization that transformed traditional agrarian economies into complex urban polities, while maintaining extreme inequality. The state is thus central in the genealogy of inequality and elite privilege in Latin America. The synergy between states and elites continues to mark Latin American societies, and it helps us to understand how major economic and political changes occur without significant changes in inequality. For the most part, Latin America's current uneven states emerged as the result of exclusionary projects of citizenship during the first half of the 20th century and were advanced by the advent of repressive regimes during the 1960s and 1970s. After democratic transitions during the 1980s and 1990s, Latin American states came to be characterized, on the one hand, by procedural democratic institutions and on the other, by high levels of state violence, exclusion, and segmented citizenship. The present situation is one of a problematic equilibrium between states, elites, and inequality.
Producing the natural: Mobilities and the managed aesthetics of nature
Authors: McCumber Andrew
Published: July 2018

Nature can be a nebulous, often contradictory concept that holds immense cultural and emotional weight for many. Philosophers and social scientists have frequently dissected its meaning and shared significance, especially with respect to environmental issues. This paper analyzes nature as experienced and understood in everyday life in Western society, arguing that the most salient, intuitive mode of understanding the concept is a visual–pictorial one. It further argues that nature is expressed through emplaced aesthetics managed and produced through various forms of “mobility,” or socially produced movement, as theorized by the writers of the “new mobilities paradigm.” The paper considers two general contexts for this process: the production of aesthetic nature in urban settings and in extra‐urban landscapes. Furthermore, it argues that these aesthetic expressions have a great influence on the epistemology guiding popular sensibilities around our broader relationships to the nonhuman world and on the moral logic of much Western environmentalism.
Metagenomics analysis of the virome of 300 concentrates from a Swiss platelet bank
Authors: Brito Francisco , Cordey Samuel , Delwart Eric , Deng Xutao , Tirefort Diderik , Lemoine‐Chaduc Coralie , Zdobnov Evgeny , Lecompte Thomas , Kaiser Laurent , Waldvogel‐Abramowski Sophie , Preynat‐Seauve Olivier
Published: July 2018

Background and objectives

Platelet concentrates are frequently transfused to patients with reduced immunity. An exhaustive description of their viral content is needed to prevent unwanted infection.

Material and methods

To track viral sequences, a shotgun metagenomics approach was used on a bank of 300 platelets concentrates. Sequences were analysed through the diagnostics‐oriented pipeline ezVIR.

Results

We only observed viruses commonly described in healthy individuals.

Conclusion

Herein is reported the first viral landscape of a platelet concentrates bank.
The Relationship Between the Sport-Confidence and the Coach-Athlete Relationship in Student-Athletes
Authors: Gencer Eylem , Öztürk Arda
Published: July 2018

The aim of this study was to examine the relationship between the sport-confidence and the coach-athlete relationship in Turkish national male student-wrestlers, and to investigate whether educational status, wrestling style, wrestling category, and career of wrestlers were significant variables on student-wrestlers’ sport confidence and their relationship with their coaches. Participants were 198 Turkish national male wrestlers. Demographic questions, the Sport-Confidence Inventory (Vealey, 1986), and the Coach Athlete Relationship Questionnaire (Jowett & Ntoumanis, 2004) were performed for data collection. Results indicated that sport-confidence was significantly related to coach-athlete relationship and sport-confidence was significant predictor of wrestlers’ relationship with their coaches. Besides, wrestling style and wrestling category were significant variables on coach-athlete relationship. However, educational status and career of wrestlers were not significant variables in terms of sport-confidence and coach-athlete relationship. In conclusion, the findings of the study highlight that the association of sport-confidence and coach-athlete relationship can contribute to the understanding of relational process in sport.
Experience of patients following lower limb joint replacement: a systematic review protocol
Authors: Makimoto Kiyoko , Fujita Kimie , Konno Rie
Published: July 2018

Review question:

The objective of this proposed review is to explore the postoperative experiences of adult patients who have undergone lower limb joint replacement. Specifically, the review question is: What are the postoperative experiences during the six-week post-discharge period of adult patients who have undergone lower limb joint replacement?
GABA beyond the synapse: defining the subtype‐specific pharmacodynamics of non‐synaptic GABAA receptors
Authors: Lagrange Andre H. , Hu NingNing , Macdonald Robert L.
Published: July 2018

Key points

Physiologically relevant combinations of recombinant GABAA receptor (GABAR) subunits were expressed in HEK293 cells. Using whole‐cell voltage clamp and rapid drug application, we measured the GABAR‐subtype‐specific properties to convey either synaptic or extrasynaptic signalling in a range of physiological contexts.

α4βδ GABARs are optimally tuned to submicromolar tonic GABA and transient surges of micromolar GABA concentrations.

α5β2γ2l GABARs are better suited to higher tonic GABA levels, but also convey robust responses to brief synaptic and perisynaptic GABA fluctuations.

α1β2/3δ GABARs function well at prolonged, micromolar (>2 μm) GABA levels, but not to low tonic (<1 μm GABA) or synaptic/transient GABAergic signalling.

These results help illuminate the context‐ and isoform‐specific modes of GABAergic signalling in the brain.

GABAA receptors (GABARs) mediate a remarkable diversity of signalling modalities in vivo. Yet most published work characterizing responses to GABA has focused on the properties needed to convey fast, phasic synaptic inhibition. We therefore aimed to characterize the most prevalent (α4βδ, α5β3γ2L) and least prevalent (α1β2δ) non‐synaptic GABAR currents, using whole‐cell voltage clamp recordings of recombinant GABAR expressed in HEK293 cells and drug application protocols to recapitulate the GABA concentration profiles occurring during both fast synaptic and slow extrasynaptic signalling. We found that α4βδ GABARs were very sensitive to submicromolar GABA, with a rank order potency of α4β2δ ≥ α4β1δ ≈ α4β3δ GABARs. In comparison, the GABA EC50 was up to 20 times higher for α1β2γ2L GABARs, with α1β2δ and α5β3γ2L GABARs having intermediate GABA potency. Both α4βδ and α5β3γ2L GABAR currents exhibited slow, but substantial, desensitization as well as prolonged rates of deactivation. These GABAR current properties defined distinct ‘dynamic ranges’ of responsiveness to changing GABA for α4β2δ (0.1–1 μm), α5β3γ2L (0.5–7 μm) and α1β2γ2L (0.6–9 μm) GABARs. Finally, α1β2δ GABARs were notable for their relative lack of desensitization and extremely quick deactivation. In summary, our results help delineate the roles that specific GABARs may play in mediating non‐synaptic GABA signals. Since ambient GABA levels may be altered during development as well as by drugs and disease states, these findings may help future efforts to understand disrupted inhibition underlying a variety of neurological illnesses, such as epilepsy.
Abnormal folate metabolism causes age‐, sex‐ and parent‐of‐origin‐specific haematological defects in mice
Authors: Padmanabhan Nisha , Menelaou Katerina , Gao Jiali , Anderson Alexander , Blake Georgina E. T. , Li Tanya , Daw B. Nuala , Watson Erica D.
Published: July 2018

Key points

Folate (folic acid) deficiency and mutations in folate‐related genes in humans result in megaloblastic anaemia.

Folate metabolism, which requires the enzyme methionine synthase reductase (MTRR), is necessary for DNA synthesis and the transmission of one‐carbon methyl groups for cellular methylation.

In this study, we show that the hypomorphic Mtrrgt/gt mutation in mice results in late‐onset and sex‐specific blood defects, including macrocytic anaemia, extramedullary haematopoiesis and lymphopenia.

Notably, when either parent carries an Mtrrgt allele, blood phenotypes result in their genetically wildtype adult daughters, the effects of which are parent specific.

Our data establish a new model for studying the mechanism of folate metabolism in macrocytic anaemia aetiology and suggest that assessing parental folate status might be important when diagnosing adult patients with unexplained anaemia.

The importance of the vitamin folate (also known as folic acid) in erythrocyte formation, maturation and/or longevity is apparent since folate deficiency in humans causes megaloblastic anaemia. Megaloblastic anaemia is a type of macrocytic anaemia whereby erythrocytes are enlarged and fewer in number. Folate metabolism is required for thymidine synthesis and one‐carbon metabolism, though its specific role in erythropoiesis is not well understood. Methionine synthase reductase (MTRR) is a key enzyme necessary for the progression of folate metabolism since knocking down the Mtrr gene in mice results in hyperhomocysteinaemia and global DNA hypomethylation. We demonstrate here that abnormal folate metabolism in mice caused by Mtrrgt/gt homozygosity leads to haematopoietic phenotypes that are sex and age dependent. Specifically, Mtrrgt/gt female mice displayed macrocytic anaemia, which might be due to defective erythroid differentiation at the exclusion of haemolysis. This was associated with increased renal Epo mRNA expression, hypercellular bone marrow, and splenic extramedullary haematopoiesis. In contrast, the male response differed since Mtrrgt/gt male mice were not anaemic but did display erythrocytic macrocytosis and lymphopenia. Regardless of sex, these phenotypes were late onset. Remarkably, we also show that when either parent carries an Mtrrgt allele, a haematological defect results in their adult wildtype daughters. However, the specific phenotype was dependent upon the sex of the parent. For instance, wildtype daughters of Mtrr+/gt females displayed normocytic anaemia. In contrast, wildtype daughters of Mtrr+/gt males exhibited erythrocytic microcytosis not associated with anaemia. Therefore, abnormal folate metabolism affects adult haematopoiesis in an age‐, sex‐ and parent‐specific manner.
Neural memory of the genioglossus muscle during sleep is stage‐dependent in healthy subjects and obstructive sleep apnoea patients
Authors: Taranto‐Montemurro Luigi , Sands Scott A. , Grace Kevin P. , Azarbarzin Ali , Messineo Ludovico , Salant Rebecca , White David P. , Wellman D. Andrew
Published: July 2018

Key points

In most patients with obstructive sleep apnoea (OSA), there is a spontaneous resolution of the breathing disorders during slow wave sleep (SWS) for yet unknown reasons related to non‐anatomical factors.

Some recently identified forms of neural memory specific of upper airway muscles may play a role in this phenomenon.

In the present study, we show for the first time that a form of memory of the genioglossus (tongue) muscle is greatly enhanced during SWS compared to non‐rapid eye movement stage 2 sleep.

The present study represents a step forward in understanding the mechanisms responsible for the spontaneous development of stable breathing during SWS in OSA patients and may help the discovery of novel therapeutic strategies for this disease.

Several studies have shown that obstructive sleep apnoea (OSA) improves during slow wave sleep (SWS) for reasons that remain unclear. Recent studies have identified forms of neural memory such as short‐term potentiation or after‐discharge that can occur in response to upper airway obstruction. Neural memory may play a role in the development of stable breathing during SWS by increasing upper airway muscles activity in this sleep stage. We hypothesize that the after‐discharge of the genioglossus muscle following upper airway obstruction is enhanced during SWS compared to non‐rapid eye movement stage 2 (N2). During sleep, we performed five‐breath drops in continuous positive airway pressure (CPAP‐drop) to simulate obstructive events and reflexively activate the genioglossus. Immediately afterwards, CPAP was returned to an optimal level. Once the post‐drop ventilation returned to eupnoea, the genioglossus after‐discharge was measured as the time it took for genioglossus activity to return to baseline levels. In total, 171 CPAP‐drops were analysed from a group of 16 healthy subjects and 19 OSA patients. A mixed‐model analysis showed that after‐discharge duration during SWS was 208% (95% confidence interval = 112% to 387%, P = 0.022) greater than during N2 after adjusting for covariates (ventilatory drive, CPAP levels). There was also a non‐significant trend for a –35% reduction in after‐discharge duration following an arousal vs. no‐arousal from sleep (95% confidence interval = –59.5% to 5%, P = 0.08). Genioglossus after‐discharge is two‐fold greater in SWS vs. N2, which could partly explain the breathing stabilization described in OSA patients during this sleep stage.
Robot Explorers
Authors: Shah Agam
Published: July 2018

Robotic space probes have proven themselves to be capable explorers, roaming the solar system, observing the galaxy, and pushing back the boundaries of the final frontier. Those looking for a return to the glory days of human space exploration will need patience. NASA is aiming for a human landing on Mars in the 2030s, though cynics might contend that a Mars mission has been “just over the horizon” for a generation. Private-sector efforts in the near term are limited to suborbital tourism. Fortunately, NASA, the European Space Agency, and groups from other countries are readying a variety of missions that should answer some of astronomy’s biggest questions, all while keeping human feet firmly on the ground. In this article, we review nine unmanned missions that will explore new frontiers in space over the next decade.
Effect of Variable Sidewall Temperatures on the Combined Surface Radiation—Convection in a Discretely Heated Enclosure
Authors: Saravanan S. , Raja N.
Published: July 2018

This paper reports the changes made in the flow and heat transfer characteristics of a closed enclosure in the presence of sidewalls with symmetrical linear heating. The flow inside the enclosure is primarily driven by a centrally placed discrete heater with thermal radiation included at all surfaces involved. Finite volume method-based computational results corresponding to the resulting steady-state were obtained. The factors causing augmentation and suppression of heat transfer are discussed for two types of sidewall heating. Moreover, it is found that the role of radiation is well stronger than convection in determining the total heat transfer rate when the sidewall heating is decreasing with height.
Emergency Medical Services Backboard With a Pressure Dispersion Liner
Authors: Henschen Matthew R. , Koesters Adam L. , Harvey Jonathan , Nemunaitis Gregory , Pourazady Mehdi , Hefzy Mohamed Samir
Published: July 2018

Spinal immobilization is of utmost importance when caring for major trauma victims. Because of the potential for spinal cord injury, trauma victims must be secured to a rigid backboard. Patients are held in position by placing blocks on either side of their head, straps across their forehead, chest, and legs. The goal of using a hard backboard is to reduce the chances of damaging the victim’s neurological functions because of movement of unstable or injured vertebrae. These backboards serve their function of patient immobilization but present another problem for the patient. They have been associated with a skin breakdown condition called decubitus ulcers (bed sores). Bed sores are areas of damaged skin and tissue that develop when sustained pressure causes a restriction of blood circulation to vulnerable parts of the body. Without adequate blood flow, the affected tissue dies. Some patients may be secured to these boards for up to four hours waiting to undergo x-rays. This is more than enough time for ulcers to reach Stage IV which is the deepest and most destructive ulcer. The incidence of pressure ulcers in newly admitted patients has been reported as high as 59% and 50% have been reported at the sacral region [1, 2]. In experimental studies performed on dogs it has been shown that a constant pressure of only 60mmHg for one hour is enough to cause irreversible tissue damage [3]. When the patients are on the backboards it has been shown that there is often a high pressure spike at the sacral prominence where average maximum interface pressure spike of 260mmHg have been noted. When a thin but very heavy gel pad was added to the backboard, the sacral interface pressure was reduced to an average maximum pressure of 188 mmHg [4]. The objective of this project is to develop a backboard with a light pressure dispersion liner to reduce interface pressures on pressure sensitive areas in the supine position.
Magnetoelastic Materials as Novel Bioactive Coatings for Bone Anchored Prostheses
Authors: Vlaisavljevich Eli , Janka Logan P. , Ong Keat G. , Rajachar Rupak M.
Published: July 2018

Enhanced fibroblast activity at the implant-soft tissue interface is a key concern to the long-term success of many implanted biomaterials. Uncontrolled fibrosis has been shown to dramatically decrease the stability, function, and lifespan of biomedical implants. Fibrosis, defined as the overgrowth of various tissues about the implant, is caused by the excess synthesis of extracellular matrix components, primarily collagen, and often leads to walling off and hardening (calcification) of tissues at the biomaterial interface (1). Fibrosis is currently a major deterrent to stable bone anchored prostheses. These bone anchored mounting systems are designed to surgically attach a prosthesis mounting post directly into a patient’s bone. The attached post protrudes from the bone through the overlying soft tissue of the amputated limb providing an external connection point for the prosthetic. Although the bone anchoring system dramatically improves prosthetic limb mechanical stability, uncontrolled fibrosis at the soft tissue-mounting post interface is a significant problem (2). The fibrosis caused from aberrant cellular growth leads to the formation of irregular skin folds that prevent proper sealing to the bone anchoring post and also serves as a site for opportunistic infection and failure of the prosthetic system.
Bi-Phasic Reverse Movement of Permeable Solute(s) in Cells is Predicted by the Relativistic Permeability Approach
Authors: Katkov Igor I.
Published: July 2018

Ternary systems water — impermeable solute (“salts”) — permeable solute have been widely used in cryopreservation of biological cells where the permeable solute is the cryoprotective agent (CPA). The cell membrane is considered “leaky”’ to CPA so the osmotic process is described by a system of two coupled non-linear equations: the osmotic equation (1.1) that drives water against the gradient of total osmotic pressure of both solutes, and the diffusion equation (1.2), which drives the permeable solute towards its gradient across membrane. In case of the “classical” system one permeable solute + impermeable entities (“salts”), the third equation (Boyle-van’t Hoff law (1.3) that states the constant amount of the impermeable components inside the cell (3) is added: (1.1)dWdt=-LpRTYf-Y+Zf-Z(1.2)dXdt=PsAYf-Y(1.3)WZ=WisoZiso=W0Z0=WfZf=const where W is the cell water volume, t is the time, Lp is the hydraulic conductivity, R is the gas constant, T is the temperature, A is the surface area, Y and Z are the osmolalities of permeable and impermeable solutes respectively, X ≡ WY is the intracellular amount (“number of osmoles”) of the permeable solute, Ps is the solute membrane permeability. Subscript “iso” refers to the isosmotic values, “0” is the values at time zero, and “f” refers to the final (equilibrium, extracellular) values. The water permeability can be considered as LpRT.
Negative Correlation of Wall Thickness With Wall Blood Pressure in a Patient-Specific Atherosclerotic Coronary Artery: A Case Report
Authors: Liu Biyue , Zheng Jie , Bach Richard , Tang Dalin
Published: July 2018

There are two major hemodynamic stresses imposed at the blood-arterial wall interface by flowing blood: the wall shear stress (WSS) acting tangentially to the wall, and the wall pressure (WP) acting vertically to the wall. These forces influence the artery wall metabolism and correspond to the local modifications of artery wall thickness, composition, microarchitecture, and compliance [2]. The role of flow wall shear stress in atherosclerosis progression has been under intensive investigation [4], while the impact of local blood pressure on plaque progression has been under-studied.
A Framework to Assess Human Coronary Plaque Vulnerability Using Intravascular Ultrasound, On-Site Pressure, Angiography, and Anisotropic FSI Models
Authors: Liu Haofei , Cai Mingchao , Yang Chun , Zheng Jie , Bach Richard , Kural Mehmet , Billiar Kristen , Muccigrosso David , Lu Dongsi , Tang Dalin
Published: July 2018

Atherosclerotic plaque rupture is believed to be associated with critical flow and stress/strain conditions. Image-based computational models have been developed to identify critical flow and stress/strain conditions in the plaque [1–3]. In vivo image-based coronary plaque modeling papers are relatively rare because clinical recognition of vulnerable coronary plaques has remained challenging [4]. In this paper, a framework adopting intravascular ultrasound (IVUS) imaging with on-site pressure and flow measurements, biaxial mechanical testing and computational modeling is proposed to construct 3D coronary plaque for more accurate stress/strain predictions.
Quantitative Comparison of 7D MRI Flow Measurements With CFD Results in a Type B Aortic Dissection
Authors: Karmonik Christof , Clough Rachel E. , Lumsden Alan B. , Taylor Peter , Bismuth Jean
Published: July 2018

Aortic dissections, which split the aorta into a true lumen (TL) and a false lumen (FL), represent a serious medical condition, affecting otherwise healthy young people with an incidence between 5,000–10,000 cases per year in the United States and 3000 in Europe [1]. A recent study of the outcome of acute type III/ Stanford B aortic dissections (dissections confined to the descending aorta, B-AD) revealed that the long-term prognosis after hospital discharge of patients with B-AD is heterogeneous, with reported survival rates ranging from 56 to 92% at 1 year and from 48 to 82% at 5 years [2]. A partially thrombosed FL, results in a 2.7-fold increase in risk of death [3]. In a recent ex-vitro study, Tasi et al. investigated a chronic aortic dissection in three models [4]. The largest FL diastolic pressure was observed for the model simulating patients with partial false lumen thrombosis and occlusion of the distal entry tear. This study demonstrated that pressure differences between TL and FL are dependent on the geometry of the particular aortic dissection and the location and size of entry tears. A computational fluid dynamics (CFD) study on the effects of entry and exit tear coverage in B-AD based on a patient-derived geometry reported similar results [5]: In particular, occlusion of the exit tear caused increase FL pressure. Simulating thoracic endovascular repair (TEVAR) by occluding the entrance tear depressurized the FL. The capability of CFD to virtually simulate surgical interventions makes it an appealing method for use in pre-surgical planning. For general acceptance however, validation of the simulated results is needed. Catheter measurements of the pressures in the TL and FL are feasible but not very practicable as insertion of a catheter in the FL through the entry or exit tear bears unjustifiable risk to the patient. More recently, 7D phase contrast magnetic resonance imaging (pcMRI) methods (3 spatial directions, 3 velocity directions and time equal 7 dimensions) have been introduced that allow the acquisition of the 3D velocity field at several time points in the cardiac cycle, thereby providing information that can be directly compared with the velocity field simulated with CFD. Due to the large duration of the image acquisition, compromises in temporal and spatial resolution are made which need to be considered when performing such a comparison. Here we present a method based on interpolating the simulated velocity field onto a structured grid employing direct interpolation and spatial Fourier Fast Transformation (FFT) to replicate artifacts as they are present in the 7D pcMRI data. The interpolated velocity components are the then qualitatively compared using image correlation analysis.
Experimental Investigation of Collagen Waviness and Orientation in Adventitia of Common Carotid Arteries of Rabbits
Authors: Agianniotis Aristotelis , Stergiopulos Nikos
Published: July 2018

The adventitia is the outermost layer of blood vessels and its mechanical properties are determined by the organization of collagen fibers in this layer. The waviness and the angular dispersion characterize the collagen fiber organization. Previous studies were mainly conducted on loaded and chemically fixed vessels, which could modify the structural organization [1]. We have combined fluorescent marker with confocal microscopy and image analysis to quantify the waviness and angular distribution of collagen fibers, and determine the correlation between the waviness distribution of fibers and their main orientation in the adventitia of rabbit common carotid arteries at their zero-stress state.
Active Axial Stress in Mouse Aorta
Authors: Agianniotis Aristotelis , Rachev Alexander , Stergiopulos Nikos
Published: July 2018

Arteries exhibit a complex mechanical behavior due to their complex structure and composition. When smooth muscle cells (SMCs) are stimulated to contract, an artery constricts and develops the so called active stress in the arterial wall. Assuming that the SMCs are oriented in the circumferential direction most of studies consider solely development of the circumferential active stress [1]. However, histological findings show existence of SMCs oriented in both the circumferential and axial direction; these vessels manifest biaxial contractile response [2, 3]. In this study we also observed biaxial contractile response and processed the experimental data to incorporate an active axial stress in the constitutive formulation of the arterial tissue.
Constitutive Models for the Passive Porcine Atria at the Healthy Stage and After Ventricular Tachypacing
Authors: Bellini Chiara , Di Martino Elena S.
Published: July 2018

Experimental measures of the mechanical response to planar biaxial loads and observations of the local arrangement of fibers were combined to generate average constitutive models for the atria at the healthy stage and after ventricular tachypacing. These models improve the understanding of the changes in the mechanical behavior of the atria induced by atrial fibrillation.
A Large Deformation Finite Element Model for Non-Communicating Hydrocephalus
Authors: Lefever Joel A. , García José Jaime , Smith Joshua H.
Published: July 2018

In a healthy brain, a continuous flow of cerebrospinal fluid (CSF) is produced in the choroid plexus, located in the lateral ventricles. Most of the CSF drains via the Sylvius aqueduct into the subarachnoid space around the brain, but a small amount flows directly through the cerebrum into the subarachnoid space inside the skull. Non-communicating hydrocephalus occurs when an obstruction blocks the Sylvius aqueduct. Because the cerebrum has only limited capacity for CSF to flow through it, CSF accumulates in the ventricles, yielding a significant increase in ventricular volume and deformation of the cerebrum, which may lead to tissue damage.
A Novel, Fast and Semi-Automatic Method to Implement Wave Intensity Analysis for Magnetic Resonance Imaging
Authors: Biglino Giovanni , Steeden Jennifer A. , Baker Catriona , Schievano Silvia , Taylor Andrew M. , Parker Kim H. , Muthurangu Vivek
Published: July 2018

Wave intensity analysis (WIA) is a time domain analysis [1] and, as a hemodynamic index, it can assess the performance of the heart and its interaction with the arterial system [2]. This quantity was originally defined as the product of the instantaneous changes in measured pressure (ΔP) and simultaneously measured velocity (ΔU). Clinical applications of WIA have previously been investigated but have been limited by the invasive nature of P and U measurements. Recently, a new formulation of wave intensity has been proposed, using a measure of changes in diameter (ΔD) instead of ΔP [3]. Two recent studies have tested this formulation by analysing retrospectively magnetic resonance (MR) images [4] and ultrasonography data [5].
Study of Hypothermia Induced by an Interstitial Cooling Device in Spinal Cord Injury
Authors: Huang Zhongping , Jin Ying , Tarabichi Saeed , Zhang Yifan , Fischer Itzhak , Zhu Liang
Published: July 2018

Previous studies have suggested that systemic hypothermia shortly following an ischemic or traumatic event to the spinal cord provided significant beneficial effects following spinal cord injury (SCI)1–3. There are two strategies for hypothermia treatment, a systemic and a local cooling. Both strategies have shown neuro-protective effects of SCI in experimental animal models and in patients; however, there is a variety of technical quandaries when applying this principal to the clinical setting, such as the use of special cooling equipment and the special surgery required to functionally implementing them. We are also concerned with the non-uniform cooling rates in the spinal cord and potential risks associated with each procedure. It is important to develop novel cooling methods to reach desired therapeutic effects while ensuring patient safety.
Microcalcification Acts as a Stress and Stretch Amplifier in the Coronary Atherosclerotic Plaque Affecting Its Vulnerability: An IVUS-Based Finite Element Study
Authors: Huang Yuan , Wang Wenkai , Teng Zhongzhao , Obaid Daniel R. , He Jing , Calvert Patrick A. , Bennett Martin R. , Gillard Jonathan H.
Published: July 2018

Atherosclerotic disease remains a leading cause of mortality and morbidity worldwide despite significant advances in its management (1). Atherosclerosis, characterized by plaque consisting a lipid-rich necrotic core encapsulated in a fibrous cap, may result in plaque rupture and subsequently cause acute ischaemic events such as myocardial infarction and stroke. Under physiological conditions, plaque is subjected to mechanical loading due to blood pressure and flow and rupture possibly occurs if these extra loadings exceed the material strength of the fibrous cap (2–4). This hypothesis has been indirectly validated by the combination of histological examination and finite element simulations that the rupture site often bears a high stress concentration either in carotid (3, 5, 6) or coronary (2) plaques. It has been noted that most rupture sites are located at the shoulder region (2), where the curvature is locally large (4) leading to a high stress level (7). However, the rupture site does not always coincide with the site where high stress concentrations appear and about thirty to forty percent of ruptures occur in the middle region where the calculated stress is relatively low (2, 8). This demonstrates the limitations of current approaches.
The Stability of Veins Under Torsion
Authors: Garcia Justin R. , Han Hai-Chao
Published: July 2018

Twisted veins are observed throughout the body and are often associated with health risks such as hypertension and diabetes mellitus [1]. Recently, it has been shown that veins will buckle and become tortuous when lumen pressure exceeds a critical value [2]. However, veins also undergo twist deformations in vivo due to body movement, vein grafting, and microanastomosis procedures which may lead to reduced patency, kinking, and thrombus formation [3, 4]. In spite of this, little data is available regarding the stability of veins when subject to twist deformations. Therefore, it is of clinical interest to investigate the mechanical stability of veins under torsion.
Head Rotation Influences the Geometric Features of the Stenotic Carotid Bifurcation
Authors: Aristokleous Nicolas , Seimenis Ioannis , Papaharilaou Yannis , Eracleous Eleni , Georgiou Georgios C. , Brott Brigitta C. , Anayiotos Andreas S.
Published: July 2018

Previous investigators have reported that posture changes may influence the geometry and hemodynamics of the carotid bifurcation [1,2]. As a result, head rotation may cause geometric changes that alter the hemodynamic variables previously cited to correlate with the development of atherosclerosis. Glor et al. [1] had reported changes in the right carotid bifurcation geometry with leftward rotation of the head. Aristokleous et al. [2] have reported that geometric differences in the right and left carotid bifurcation occur with a rightward rotation of the head in 10 healthy volunteers [2]. Also, a similar study on bilateral head rotation on the left and right carotid bifurcation of two volunteers has shown similar results [3]. In this study a group of four patients with atherosclerotic disease in the carotid arteries was investigated at two head postures, a) the supine neutral and b) the prone sleeping with head rotation leftwards up to 80° to investigate the level of stenosis and the changes in geometric parameters with head rotation.
Analysis of Electrokinetic Fluid Flow in T-Shaped DNA Chips
Authors: Panta Yogendra M. , Aryal Sanket , Adhikari Param C.
Published: July 2018

Lab-on-chip devices promise for many novel applications concerning the transport of the liquid samples and other solutions in the order of micro-scale dimensions. One of the efficient methods for transporting fluid in the samples is through electrokinetic effects, where an electric field will be applied to charged ions such as DNA, a negatively charged ion or proteins. These ions are carried over in the microchannel by the application of electric fields through the entire solution from inlet via probe region for its detection to outlet and the determination of concentration distribution. COMSOL, commercially available multiphysics software, with its specific MEMS and Chemical Engineering modules were employed and simulated for the analysis of fluid velocity and ionic concentration throughout the channel of various shapes. The ionic fluid concentrations and velocities in the channel and at the outlet are plotted against the potential differences across the two inlets in which DNA sample was introduced from one inlet and a buffer solution was supplied from another inlet.
Autonomous Sorting of Micro-Particles Using Bacterial Chemotaxis
Authors: Traore Mahama A. , Behkam Bahareh
Published: July 2018

The autonomous manipulation and assembly at the micro and nanoscale continues to be one of the main challenges in the field of micro/nanorobotics. On the other hand, biomotors are increasingly being considered as robust, versatile and cost-effective choices for a variety of micro/nanorobotic tasks. Here we propose the utilization of the motility and chemotaxis in flagellated bacteria to autonomously sort spherical particles with 6 μm and 10 μm in diameter within a microfluidic platform. Surface chemistry methods are utilized to selectively self-assemble bacteria onto the 6 μm diameter particles and separate them from 10 μm diameter particles via chemotaxis. It has been shown that within 1 hour, an increasingly larger number of 6 μm diameter particles accumulate within a 600 μm radius, near the chemo-attractant source.
Finite Element Analysis of the Patellofemoral Joint Behavior Under Frontal Impact
Authors: Mustafy Tanvir , El-Rich Marwan , Islam Kamrul , Adeeb Samer
Published: July 2018

Lower extremity injuries are a frequent outcome of automobile accidents (Fildes et al., 1997). These injuries can be a cause of permanent disability and impairment (States, 1986). Luchter and Walz (1995) found that the lower extremity was the most frequently injured body region, comprising 27.8% of the injuries in the 1993 National Accident Sampling System (NASS) database. Patella and femur fractures are the most frequent knee injuries.
A second chance
Authors: Enserink Martin
Published: July 2018

On a remote Melanesian island, a Spanish doctor has revived the 60-year-old quest to eradicate a disfiguring disease.
Mixed tailing by TENT4A and TENT4B shields mRNA from rapid deadenylation
Authors: Lim Jaechul , Kim Dongwan , Lee Young-suk , Ha Minju , Lee Mihye , Yeo Jinah , Chang Hyeshik , Song Jaewon , Ahn Kwangseog , Kim V. Narry
Published: July 2018

A tale of not-so-pure tails

The poly(A) tail of mRNA has been thought to be a pure stretch of adenosine nucleotides with little informational content except for length. Lim
et al.
identified enzymes that can decorate poly(A) tails with non-A nucleotides. The noncanonical poly(A) polymerases, TENT4A and TENT4B, incorporate intermittent non-A residues (G, U, or C) with a preference for guanosine, which results in a heterogenous poly(A) tail. Deadenylases trim poly(A) tails to initiate mRNA degradation but stall at the non-A residues. In effect, the not-so-pure tail stabilizes mRNAs by slowing down deadenylation.

Science
, this issue p.
701
Wallpaper fermions and the nonsymmorphic Dirac insulator
Authors: Wieder Benjamin J. , Bradlyn Barry , Wang Zhijun , Cano Jennifer , Kim Youngkuk , Kim Hyeong-Seok D. , Rappe Andrew M. , Kane C. L. , Bernevig B. Andrei
Published: July 2018

Exotic topology on the surface

Analyzing the spatial symmetries of three-dimensional (3D) crystal structures has led to the discovery of exotic types of quasiparticles and topologically nontrivial materials. Wieder
et al.
focus on the symmetry groups of 2D surfaces of 3D materials—the so-called wallpaper groups—and find that some of them allow for an additional topological class. This class hosts a single fourfold-degenerate Dirac fermion on the surface of the material and, on the basis of the authors' calculations, is expected to occur in the compound Sr
2
Pb
3
.

Science
, this issue p.
246
Atmospheric new particle formation from sulfuric acid and amines in a Chinese megacity
Authors: Yao Lei , Garmash Olga , Bianchi Federico , Zheng Jun , Yan Chao , Kontkanen Jenni , Junninen Heikki , Mazon Stephany Buenrostro , Ehn Mikael , Paasonen Pauli , Sipilä Mikko , Wang Mingyi , Wang Xinke , Xiao Shan , Chen Hangfei , Lu Yiqun , Zhang Bowen , Wang Dongfang , Fu Qingyan , Geng Fuhai , Li Li , Wang Hongli , Qiao Liping , Yang Xin , Chen Jianmin , Kerminen Veli-Matti , Petäjä Tuukka , Worsnop Douglas R. , Kulmala Markku , Wang Lin
Published: July 2018

A puzzle of new particles

Atmospheric particulates can be produced by emissions or form de novo. New particle formation usually occurs in relatively clean air. This is because preexisting particles in the atmosphere will scavenge the precursors of new particles and suppress their formation. However, observations in some heavily polluted megacities have revealed substantial rates of new particle formation despite the heavy loads of ambient aerosols. Yao
et al.
investigated new particle formation in Shanghai and describe the conditions that make this process possible. The findings will help inform policy decisions about how to reduce air pollution in these types of environments.

Science
, this issue p.
278