bluuebunny/crossref_metadata_2025 huggingface dataset:
A Preliminary Study on the Effect and Mechanism of Breviscapine for Improving Insulin Resistance in HepG2 Cells
Authors: Yan Fangyan , Feng Jibo , Li Weiping , Wu Li , Li Jinping
Published: May 2020

Insulin resistance (IR) is known to be a critical factor, which can lead to the onset of type 2 diabetes. Traditional Chinese medicine (TCM) has special advantages in treating IR, but the active components and action mechanisms of most TCM remain unclear. Therefore, the elucidation of the potential mechanisms is a major challenge in TCM research. In the study, we tried to elucidate the potential pharmacological efficacy and mechanism of breviacapine for improving IR through network analysis and validate the possible biological target for its quality evaluation. We computationally recognized the active components, potential targets, and the targets closely related to IR by using integrative analysis based on network pharmacology approach. We also established the active components-targets network, protein interactions network and analyzing the biological functions and pathways of targets to evaluate the links between components and pharmacological actions to help explain the action mechanisms of breviscapine. Based on the network analysis, our experimental data preliminarily confirmed that breviscapine could improve IR in HepG2 cells, which may be associated with the dynamic regulation of the PTP1B. This study combined network pharmacology with partial experiment validation to clarify the underlying mechanism of breviscapine in improving IR and thus laid the experimental foundation for the depth exploration of its functional mechanism.
Emerging Dematiaceous and Hyaline Fungi Causing Keratitis in a Tertiary Care Centre From North India
Authors: Ghosh Anup , Kaur Harsimran , Gupta Amit , Singh Shreya , Rudramurthy Shivaprakash Mandya , Gupta Sunita , Chakrabarti Arunaloke
Published: May 2020

Purpose:

To report rare dematiaceous and hyaline fungal pathogens causing fungal keratitis (FK) at our center and review the published literature in this field.

Methods:

In a retrospective review of FK cases from 2005 to 2011, a total of 14 rare pathogens causing isolated cases of FK of a total of 393 isolates were revived from our collection and reconfirmed by using molecular techniques. The in vitro antifungal susceptibility testing (AFST) was performed against a 6-antifungal drug panel by the CLSI microbroth-dilution method. We reviewed the literature on keratitis due to these rare fungi.

Results:

Two novel fungi, Alternaria tenuissima and Epicoccum nigrum, were reported in addition to 6 dematiaceous (black pigmented) fungi (Acrophialophora fusispora, Chaetomium globosum, Cladophialophora carionii, Nigrospora sphaerica, Papulaspora equi, and Scytalidium lignicola), 5 hyaline (colorless) fungi (Aspergillus tamarii, Fusarium chlamydosporum, Fusarium incarnatum, Fusarium lichenicola, and Fusarium sacchari), and one yeast (Trichosporon asahii). Amphotericin B had good in vitro activity (minimum inhibitory concentration [MIC] ≤1 μg/mL) against most dematiaceous fungi, but not hyaline fungi (MIC ≥1 μg/mL). Natamycin showed variable MIC, itraconazole and voriconazole had good in vitro activity, except in Fusarium species. Alternaria tenuissima and A. fusispora had a very high MIC (≥16 μg/mL) against echinocandins. Literature search revealed 27 FK cases due to F. lichenicola (n = 6), P. equi (n = 5), F. sacchari (n = 4), A. fusispora (n = 3), S. lignicola (n = 2), and others (n = 7), and more than 50% of these were reported from India.

Conclusions:

Plant fungal pathogens with variable antifungal susceptibility are an emerging cause of human keratitis with predominance of dematiaceous fungi. Identification and antifungal susceptibility testing are important for epidemiology and to optimize therapy and improve the patient outcome.
Risk factors for postlaser refractive surgery corneal ectasia
Authors: Jin Sierra X. , Dackowski Evan , Chuck Roy S.
Published: May 2020

Purpose of review

To summarize newly reported and update previously known risk factors for post laser vision correction (LVC) corneal ectasia.

Recent findings

Advances in corneal topography and tomography have improved detection of preclinical ectasia-related changes. This has allowed for enhanced screening of surgical candidates. There are also known genetic predispositions for corneal ectasia, and recent genetic analyses have revealed various genes and inflammatory biomolecular markers related to corneal biomechanical integrity. Other models of risk assessment such as finite element biomechanical modeling and artificial intelligence tools have shown promise in detecting more subtle risk factors, such as those related to mechanical strain.

Risk factors for post-LVC corneal ectasia involve both surgery and patient-specific characteristics, such as topographic and tomographic abnormalities, younger age, thinner preoperative corneas, and residual stromal beds, high myopia, and higher percentage tissue altered. Preoperative risk stratification has helped to decrease the incidence of postoperative ectasia, a trend which will likely continue with advancements in analytic tools and better understanding of underlying genetic predispositions.
Characterization of Congenital Toxoplasmosis in Israel
Authors: Kahan Yaara , Avidar Michal , Gottesman Bat-Sheva , Riklis Irena , Dveyrin Zeev , Dalal Ilan , Meir Michal , Glikman Daniel , Bilavsky Efraim , Sherman Gilad , Shehadeh Shereen , Tasher Diana ,   for Israeli Congenital Toxoplasmosis Research Group
Published: May 2020

Background:

Congenital toxoplasmosis (CT) can cause significant neurologic manifestations and other untoward sequelae. Neither the current epidemiology nor the disease severity of CT in Israel is known.

Methods:

Records of CT were collected from the National Toxoplasmosis Reference Laboratory and from 15 medical centers across Israel between 2001 and 2017. Eligible case-patients were fetuses or infants <12 months of age at the time of diagnosis.

Results:

Of the 43 CT cases identified, 24 (55%) were in Jews and the remaining 19 cases were in patients of Arab (non-Bedouin) origin. The overall annual estimated rate of symptomatic CT was calculated as 0.55 per 100,000 live births. One or more severe clinical manifestations were reported in 12 (46%) of the 28 live-born infants and included cerebral calcifications (7 cases), chorioretinitis (4 cases), hydrocephalus (2 cases) and 1 case of death. Sensitivities of blood polymerase chain reaction (PCR), cerebrospinal fluid PCR and IgM antibody tests were 50% each. However, analyzing PCR samples from both sites, together with IgM testing, increased the sensitivity to 93%.

Conclusions:

The relative rate of severe manifestations was higher than in previous European reports. It is possible that the greater disease severity observed in Israel is in part due to the lack of systematic antenatal treatment and screening. Arab (non-Bedouin) infants are at higher risk for contracting CT. Performing serologic and PCR tests simultaneously is essential to improve CT diagnosis. This study demonstrates a need for an educational program to target high-risk populations.
Frequency of Dosing of Cephalexin for Oral Step-Down Therapy of Pediatric Osteoarticular Infections Caused by Methicillin-Sensitive Staphylococcus Aureus
Authors: Ramchandar Nanda , Arnold John , Cannavino Chris , Bradley John S.
Published: May 2020

Osteoarticular infections are one of the more common invasive bacterial infections encountered in children. There exist significant practice variations in both the diagnosis and treatment of such infections. However, the practice of transitioning from parenteral therapy to oral antibiotics has been well validated by several studies. For methicillin-sensitive Staphylococcus aureus (MSSA), cephalexin is often recommended. Prospective, controlled data regarding optimal dosing of cephalexin in pediatric osteomyelitis are not available. We sought to review our retrospective, uncontrolled data on four times daily (QID) versus three times daily (TID) dosing of cephalexin for pediatric osteoarticular infections. Children ≥1 month to <18 years of age admitted to Rady Children’s Hospital-San Diego with a diagnosis of osteomyelitis or septic arthritis between January 1, 2002, and November 30, 2007, were identified and previously reported. Only patients with culture-positive MSSA infections are included in this report. Demographic and clinical data were manually extracted from the electronic medical record. Fifty-nine patients were treated with cephalexin and had records available for review through our electronic medical record. Thirty-eight patients (64.4%) were treated QID, and 21 patients (35.6%) were treated TID. Clinical cure was achieved in all patients with only one adverse event occurring in the QID group. In this retrospective chart review of children with osteoarticular infections caused by MSSA treated with cephalexin, similar clinical outcomes were found with QID versus TID dosing.
Deoxyuracil in DNA in health and disease
Authors: Chakraborty Joydeep , Stover Patrick J.
Published: May 2020

Purpose of review

Genome instability has long been implicated as a primary causal factor in cancer and diseases of aging. The genome is constantly under attack from extrinsic and intrinsic damaging agents. Uracil misincorporation in DNA and its repair is an intrinsic factor resulting in genomic instability and DNA mutations. Additionally, the presence of uracil in DNA can modify gene expression by interfering with promoter binding and transcription inhibition or upregulation of apoptotic proteins. In immune cells, uracil in DNA drives beneficial genomic diversity for antigen-driven immunity. This review addresses diseases that are linked to uracil accumulation in DNA, its causes, consequences, and the associated biomarkers of risk factors.

Recent findings

Elevated genomic uracil is associated with megaloblastic anemia, neural tube defects, and retroviral immunity. Current evidence supporting causal mechanisms and nutritional interventions that rescue impaired pathways associated with uracil accumulation in DNA are summarized in this review.

Nutritional deficiencies in B vitamins can cause uracil misincorporation into DNA leading to genome instability and associated diseases. Nutritional approaches to preventing uracil accumulation in DNA show some promise to address its associated diseases, but additional randomized controlled trials are needed.
Applying the original model for end-stage liver disease score rather than the model for end-stage liver disease-Na score for risk stratification prior to transjugular intrahepatic portosystemic shunt procedures
Authors: Lee Brian T. , Yang Alexander H. , Urban Seth , Kim Ki-Yoon , Ter-Oganesyan Ramon , Yuan Liyun , Han Hyosun H. , Khemichian Saro , Kahn Jeffrey A. , Kim Brian
Published: May 2020

Objective

The model for end-stage liver disease (MELD) score can be used to predict survival of patients undergoing transjugular intrahepatic portosystemic shunt procedures (TIPS). The effect of hyponatremia on survival resulted in the development of the MELD-Na score. The aim of this study is to compare the prognostic value of MELD and MELD-Na scores in predicting post-TIPS outcomes.

Methods

A retrospective chart review was performed on consecutive patients with cirrhosis who underwent TIPS placement from 2012 to 2017. Indications for TIPS were either refractory ascites or variceal bleeding. Primary outcomes analyzed were death or liver transplantation. Follow-up data were censored at 1 year.

Results

Eighty-three patients underwent TIPS. There was no difference in MELD or MELD-Na score between indication groups. However, the delta MELD (MELD-Na subtracted by MELD score) was higher in those with refractory ascites. There was no difference in outcomes of death or liver transplantation between the MELD and MELD-Na at 1 year. (area under the curve 0.79 vs 0.72, respectively, P = 0.119). In patients with a MELD-Na greater than 18, higher delta MELD was protective (hazard ratio 0.74, P < 0.05).

Conclusions

There was no prognostic difference using either score despite a higher delta MELD in those with refractory ascites. The decision to pursue TIPS should utilize the original MELD score, as the MELD-Na score alone may exclude patients with refractory ascites who may benefit from TIPS.
Uric acid stone disease: lessons from recent human physiologic studies
Authors: Tran Triet Vincent M. , Maalouf Naim M.
Published: May 2020

Purpose of review

An overly acidic urine resulting in supersaturation of urine with respect to uric acid is the major mechanism responsible for uric acid nephrolithiasis. The present review summarizes findings from recent human physiologic studies examining the pathophysiology and reversibility of low urine pH in uric acid stone formers.

Recent findings

Epidemiologic and metabolic studies have confirmed an increase in the prevalence of uric acid nephrolithiasis and reported its association with several features of the metabolic syndrome including dyslipidemia, hyperglycemia, hepatic steatosis, and greater visceral adiposity. Physiologic studies in uric acid stone formers have identified diet-independent excessive net acid excretion and concomitant reduction in urinary buffering from impaired renal ammoniagenesis as the two causes underlying the greater aciduria. Administration of the insulin sensitizer pioglitazone to uric acid stone formers reduced the acid load presented to the kidney and enhanced ammoniagenesis and ammonium excretion, resulting in significantly higher urine pH.

Recent human physiologic studies have identified greater acid excretion and reduced urinary buffering by ammonia as two culprits of aciduria in uric acid nephrolithiasis that can be reversed by pioglitazone, raising new questions regarding the origin of the aciduria and opening the door to pathophysiology-based treatment of uric acid stones.
Lessons from rodent gastric bypass model of enteric hyperoxaluria
Authors: Kwenda Elizabeth P. , Rabley Andrew K. , Canales Benjamin K.
Published: May 2020

Purpose of review

The aim of the article is to review studies on bone health and oxalate metabolism/therapeutics in the obese rodent model of Roux-en-Y gastric bypass (RYGB) and examine pathways to decrease procedural morbidity.

Recent findings

Compared with controls, RYGB rodents have up to 40-fold more fat in their stool (steatorrhea) which positively correlates to increased urinary oxalate. These unabsorbed intestinal fatty acids bind calcium and prevent gut calcium oxalate formation, increasing soluble luminal oxalate availability and absorption (enteric hyperoxaluria). When intraluminal fecal fat exceeded about 175 mg/24 h in our model, more paracellular and transcellular oxalate transport across the distal colon occurred. Increasing dietary calcium and colonization with Oxalobacter formigenes reduced hyperoxaluria, whereas vitamin B6 supplementation did not. RYGB animals, when severely calcium deficient, had bone mineral density loss that could not be rescued with vitamin D supplementation.

The findings of hyperoxaluria, steatorrhea, and decreased bone mineral density are seen in both human and rodent RYGB. Our model suggests that a low-fat, low-oxalate diet combined with calcium supplementation can decrease urinary oxalate and improve skeletal bone health. Our model is a useful tool to study renal and bone RYGB effects. Studies of longer duration are required to further evaluate mechanisms of disease and durability of therapeutics.
Sense of Coherence and Mortality: A Systematic Review and Meta-Analysis
Authors: Piiroinen Ilkka , Tuomainen Tomi-Pekka , Tolmunen Tommi , Kauhanen Jussi , Kurl Sudhir , Nilsen Charlotta , Suominen Sakari , Välimäki Tarja , Voutilainen Ari
Published: May 2020

Objective

The aim of the study was to investigate the association between sense of coherence (SOC) and all-cause mortality in the general adult population.

Methods

We conducted a systematic review and meta-analysis of prospective cohort studies. We searched eight electronic bibliographic databases for eligible studies. A random effects model and the restricted maximum likelihood method were used to calculate the pooled effect size.

Results

Eight studies were eligible for the meta-analysis. The studies included 48,138 participants, of whom 5307 died during a median follow-up of 14.1 years (range, 8–29.5 years). Their age ranged from 20 to 80 years, and 53% of them were men. In the meta-analysis model of crude values, the risk of all-cause mortality for individuals with a weak SOC (lowest tertile) was 1.30 (95% confidence interval [CI] = 1.09–1.55, p = .003, I
2 = 78.84%) compared with individuals with a strong SOC (highest tertile). In the model adjusted for age, the risk remained almost the same (risk ratio = 1.26, 95% CI = 1.15–1.38, p < .001, I
2 = 69.59%). In the model adjusted for several other risk factors for mortality, the risk was still 1.17 (95% CI = 1.07–1.27, p < .001, I
2 = 57.85%).

Conclusions

This meta-analysis shows that a weak SOC is associated with an increased risk of all-cause mortality in the general adult population. Future studies are needed to further develop assessment tools for SOC with good psychometric properties and to determine the disease processes that mediate the association of SOC with mortality.
Neurological Emergencies in Patients Hospitalized With Nonneurological Illness
Authors: Jeon Sang-Beom , Lee Han-Bin , Koo Yong Seo , Lee Hyunjo , Lee Jung Hwa , Park Bobin , Choi Soh Hyun , Jeong Suyeon , Chang Jun Young , Hong Sang-Bum , Lim Chae-Man , Lee Sang-Ahm
Published: May 2020

Objective

We aimed to present neurological profiles and clinical outcomes of patients with acute neurological symptoms, which developed during hospitalization with nonneurological illness.

Methods

We organized the neurological alert team (NAT), a neurological rapid response team, to manage in-hospital neurological emergencies. In this registry-based study, we analyzed the clinical profiles and outcomes of patients who were consulted to the NAT. We also compared the 3-month mortality of patients with acute neurological symptoms with that of patients without acute neurological symptoms.

Results

Among the 85,507 adult patients, 591 (0.7%) activated the NAT. The most common reason for NAT activation was stroke symptoms (37.6%), followed by seizures (28.6%), and sudden unresponsiveness (24.0%). The most common diagnosis by the NAT neurologists was metabolic encephalopathy (45.5%), followed by ischemic stroke (21.2%) and seizures or status epilepticus (21.0%). Patients with NAT activation had high rates in mortality before hospital discharge (22.5%) and at 3 months (34.7%), transfer to intensive care units (39.6%), and length of hospital stay (43.1 ± 57.1 days). They also had high prevalence of poor functional status (78.1%) and recurrence of neurological symptoms at 3 months (27.2%). In a Cox proportional hazards model, patients with in-hospital neurological emergencies had a hazard ratio of 13.2 in terms of mortality at 3 months (95% confidence interval, 11.5–15.3; P < 0.001).

Conclusions

Occurrence of acute neurological symptoms during hospital admission was associated with high rate of mortality and poor functional status. These results call for enhanced awareness and hospital-wide strategies for managing in-hospital neurological emergencies.
Sustaining the Gains: A 7-Year Follow-Through of a Hospital-Wide Patient Safety Improvement Project on Hospital-Wide Adverse Event Outcomes and Patient Safety Culture
Authors: Sim Ming Ann , Ti Lian Kah , Mujumdar Sandhya , Chew Sophia Tsong Huey , Penanueva Donna Joy B. , Kumar Bhuvaneshwari Mohan , Ang Sophia Bee Leng
Published: May 2020

Objectives

Adverse events (AEs) remain a challenge in tertiary healthcare with incidence rates of 4% to 14%, where half are potentially preventable. Reported patient safety strategies rarely involve changing the practices of an entire academic institution and maintaining sustainability. We hypothesize that implementing an effective patient safety strategy (PSS) improves hospital-wide AE rates, cost avoidance, and patient safety culture.

Methods

A 3-stage hospital-wide PSS was implemented from 2012 to 2016, involving a top-down, bottom-up approach in a 1171-bed academic institution. The primary outcome was the incidence, preventability, and severity of hospital-wide AEs, calculated through the Institute of Healthcare Improvement, Global Trigger Tool method (incidence), National Coordinating Council for Medication Error Reporting and Prevention tool (severity), and a preventability decision algorithm (preventability). Secondary outcomes include hospital-wide cost savings and patient safety climate survey results.

Results

A total of 15,120 random chart reviews were performed across 430,868 admissions from 2012 to 2018. Overall, AE rates decreased from 11.6% to 5.4% (R
2 = 0.71, P = 0.017). The incidence of preventable AEs declined from 5.7% to 2.0% (R
2 = 0.80, P = 0.006). The severity of AEs reduced, with the proportion of category G, H, and I AEs decreasing from 8.4% (2012) to 2.6% (2018). A total of 15,960 hospital-wide patient safety climate surveys were administered from 2011 to 2016, demonstrating an improvement in hospital-wide percentage positive patient safety grade from 46.5% pre-PSS to 58.3% post-PSS implementation. This was accompanied by an 82% increase in voluntary event reporting, and cost savings of 20,600 bed-days and U.S. $29.2 million upon completion of stage 3 (2012–2016).

Conclusions

The hospital-wide PSS resulted in significant improvements in the incidence and severity of AEs, healthcare cost savings, and patient safety culture, demonstrating sustainability for 7 years.
Modification of Septal Window to Improve Angled Endoscopic View for Beyond Maxillary Sinus
Authors: Kim Boo-Young , Jeon Jeongbee , Lee Seoungmin
Published: May 2020

Many endoscopic surgeons have showed various techniques on septal window using endoscopic tools. However, each technique has its own merits and faults. In this study, the authors introduce simple and time saving endoscopic window technique by avoiding intranasal suture resulting from simple incision line. The procedure to make septal window is to improve an angled endoscopic view for beyond lateral wall of maxillary sinus with septum preservation. To date, this approach has shown no major or concerning complications and has also showed favorable disease control outcomes while maintaining nasal airway patency and functionality through our experience.
Global Survey on Pancreatic Surgery During the COVID-19 Pandemic
Authors: Oba Atsushi , Stoop Thomas F. , Löhr Matthias , Hackert Thilo , Zyromski Nicholas , Nealon William H. , Unno Michiaki , Schulick Richard D. , Al-Musawi Mohammed H. , Wu Wenming , Zhao Yupei , Satoi Sohei , Wolfgang Christopher L. , Abu Hilal Mohammad , Besselink Marc G. , Del Chiaro Marco
Published: May 2020

Objective:

The aim of this study was to clarify the role of pancreatic surgery during the COVID-19 pandemic to optimize patients’ and clinicians’ safety and safeguard health care capacity.

Summary Background Data:

The COVID-19 pandemic heavily impacts health care systems worldwide. Cancer patients appear to have an increased risk for adverse events when infected by COVID-19, but the inability to receive oncological care seems may be an even larger threat, particularly in case of pancreatic cancer.

Methods:

An online survey was submitted to all members of seven international pancreatic associations and study groups, investigating the impact of the COVID-19 pandemic on pancreatic surgery using 21 statements (April, 2020). Consensus was defined as >80% agreement among respondents and moderate agreement as 60% to 80% agreement.

Results:

A total of 337 respondents from 267 centers and 37 countries spanning 5 continents completed the survey. Most respondents were surgeons (n = 302, 89.6%) and working in an academic center (n = 286, 84.9%). The majority of centers (n = 166, 62.2%) performed less pancreatic surgery because of the COVID-19 pandemic, reducing the weekly pancreatic resection rate from 3 [interquartile range (IQR) 2–5] to 1 (IQR 0–2) (P < 0.001). Most centers screened for COVID-19 before pancreatic surgery (n = 233, 87.3%). Consensus was reached on 13 statements and 5 statements achieved moderate agreement.

Conclusions:

This global survey elucidates the role of pancreatic surgery during the COVID-19 pandemic, regarding patient selection for the surgical and oncological treatment of pancreatic diseases to support clinical decision-making and creating a starting point for further discussion.
Practical Considerations for Solid Organ Transplantation During the COVID-19 Global Outbreak: The Experience from Singapore
Authors: Chung Shimin Jasmine , Tan Ek Khoon , Kee Terence , Krishnamoorthy Thinesh Lee , Phua Ghee Chee , Sewa Duu Wen , Ong Boon-Hean , Tan Teing Ee , Sivathasan Cumaraswamy , Gan Huei Li Valerie , Goh Brian Kim Poh , Jeyaraj Prema Raj , Tan Ban Hock
Published: May 2020

The current coronavirus disease 2019 (COVID-19) pandemic has not only caused global social disruptions but has also put tremendous strain on healthcare systems worldwide. With all attention and significant effort diverted to containing and managing the COVID-19 outbreak (and understandably so), essential medical services such as transplant services are likely to be affected. Closure of transplant programs in an outbreak caused by a highly transmissible novel pathogen may be inevitable owing to patient safety. Yet program closure is not without harm; patients on the transplant waitlist may die before the program reopens. By adopting a tiered approach based on outbreak disease alert levels, and having hospital guidelines based on the best available evidence, life-saving transplants can still be safely performed. We performed a lung transplant and a liver transplant successfully during the COVID-19 era. We present our guidelines and experience on managing the transplant service as well as the selection and management of donors and recipients. We also discuss clinical dilemmas in the management COVID-19 in the posttransplant recipient.
Global strategy for New Psychoactive Substances: an update
Authors: Vicknasingam Balasingam , Narayanan Suresh , Singh Darshan , Corazza Ornella
Published: May 2020

Purpose of review

The aim of this review is to provide an update on recent trends of New Psychoactive Substances (NPS) and the current global strategies implemented to manage them.

Recent findings

The number of NPS has increased from 166 in 2009 to 892 in 2018, with about 36% having stimulant effects. Such trend revels some unprecedented patterns. The decline in the emergence of new synthetic cannabinoids has coincided with rising deaths due to overdose of fentanyl and non-fentanyl compounds in North America and Europe. The detection of new stimulant NPS has stabilized since 2015. Although the level of seizures of mephedrone have risen since then, they are still below the levels reported before international control. The legal status of kratom still remains unclear, whereas calls for research on its benefits continue. The nonmedical use of tramadol in Africa and Middle East is a cause of growing concern.

Although the rise of NPS is a cause for concern, evidence suggests that the strategy to face the challenge should include updating international data collection systems, integrating scientific-based interventions for drug use, strengthening national monitoring, and increasing collaborative research and forensic capabilities. The legal, regulatory framework and clinical guidelines should remain dynamic, whereas enforcement agencies should measure success by destroying drug networks as seizures rarely dismantle drug markets.
Prey speed influences the speed and structure of the raptorial strike of a ‘sit-and-wait’ predator
Authors: Rossoni Sergio , Niven Jeremy E.
Published: May 2020

Predators must often employ flexible strategies to capture prey. Particular attention has been given to the strategies of visual predators that actively pursue their prey, but sit-and-wait predators have been largely overlooked, their strategies often characterized as stereotyped. Praying mantids are primarily sit-and-wait predators that often employ crypsis to catch their prey using a raptorial strike produced by their highly modified forelimbs. Here, we show that the raptorial strike of the Madagascan marbled mantis (Polyspilota aeruginosa) varies in duration from 60 to 290 ms due to the tibial extension alone; slower strikes involve slower tibial extensions that may also be interrupted by a pause. The success of a strike is independent of its duration or the presence of these pauses. However, prey speed affects the duration of tibial extension and the probability of a pause occurring, both increasing at slower prey speeds. Adjusting the duration of the tibial extension according to prey speed allows mantids to time the final downward sweep of the tibia to their prey's approach. The use of visual inputs to adjust the motor pattern controlling forelimb movements shows that not all aspects of the strike are stereotyped and that sit-and-wait predators can produce behavioural flexibility.
A novel pattern of germ cell divisions in the production of hymenopteran insect eggs
Authors: Eastin Katherine J. , Huang Austin P. , Ferree Patrick M.
Published: May 2020

Egg development is a defining process of reproduction in higher eukaryotes. In the fruit fly,Drosophila melanogaster, this process begins with four mitotic divisions starting from a single germ cell, producing a cyst of 16 cystocytes; one of these cells will become the oocyte and the others supporting nurse cells. These mitotic divisions are exceptional because cytokinesis is incomplete, resulting in the formation of cytoplasmic bridges known as ring canals that interconnect the cystocytes. This organization allows all cystocytes to divide synchronously during each mitotic round, resulting in a final, power-of-2 number of germ cells. Given that numerous insects obey this power-of-2 rule, we investigated if strict cell doubling is a universal, underlying cause. Using confocal microscopy, we found striking departures from this paradigm in three different power-of-2 insects belonging to the Apocrita suborder (ants, bees and wasps). In these insects, the earliest-formed cystocytes cease to divide during the latter mitotic cycles while their descendants undergo further division, thereby producing a ‘radial’ direction of division activity. Such cystocyte division patterns that depart from strict cell doubling may be ‘fine-tuned’ in order to maintain a final, power-of-2 germ cell number.
Surface morphology enhances deposition efficiency in biomimetic, wind-driven fog collection
Authors: Shahrokhian A. , Feng J. , King H.
Published: May 2020

Passive interception of fog from the wind is an effective solution for accessing water in regions where fog is frequent and other sources scarce. A Namib Desert beetle is often cited as bioinspiration for further advancement, in a narrative which focuses on patterned wettability of its bumpy elytra as a means of transporting accumulated water from its back to its mouth. However, surface transport in fog collection is secondary to the role of the fluid dynamics of droplet deposition, in which inertial droplets migrate across diverging streamlines approaching an obstruction. 3D geometry of biological surface features inevitably affect this process, but its specific role in flow physics of fog collection has not previously been explored. Here, we report experimental measurements of deposition efficiency of targets with identical surface chemistry but varying surface morphology. We find a nearly threefold increase in collection upon addition of millimetric bumps to a spherical target, and provide insight into the micromechanics underlying the performance. Modifying surface morphology can be easier than overall geometry for both manufactured structures and evolved organisms and should therefore be both considered in the design of separation devices and expected in other biological systems for which extraction of particles from flow is important.
Sequential experimental design for predator–prey functional response experiments
Authors: Moffat Hayden , Hainy Markus , Papanikolaou Nikos E. , Drovandi Christopher
Published: May 2020

Understanding functional response within a predator–prey dynamic is a cornerstone for many quantitative ecological studies. Over the past 60 years, the methodology for modelling functional response has gradually transitioned from the classic mechanistic models to more statistically oriented models. To obtain inferences on these statistical models, a substantial number of experiments need to be conducted. The obvious disadvantages of collecting this volume of data include cost, time and the sacrificing of animals. Therefore, optimally designed experiments are useful as they may reduce the total number of experimental runs required to attain the same statistical results. In this paper, we develop the first sequential experimental design method for predator–prey functional response experiments. To make inferences on the parameters in each of the statistical models we consider, we use sequential Monte Carlo, which is computationally efficient and facilitates convenient estimation of important utility functions. It provides coverage of experimental goals including parameter estimation, model discrimination as well as a combination of these. The results of our simulation study illustrate that for predator–prey functional response experiments sequential design outperforms static design for our experimental goals. R code for implementing the methodology is available viahttps://github.com/haydenmoffat/sequential_design_for_predator_prey_experiments.
Force networks, torque balance and Airy stress in the planar vertex model of a confluent epithelium
Authors: Jensen Oliver E. , Johns Emma , Woolner Sarah
Published: May 2020

The vertex model is a popular framework for modelling tightly packed biological cells, such as confluent epithelia. Cells are described by convex polygons tiling the plane and their equilibrium is found by minimizing a global mechanical energy, with vertex locations treated as degrees of freedom. Drawing on analogies with granular materials, we describe the force network for a localized monolayer and derive the corresponding discrete Airy stress function, expressed for each
N
-sided cell as
N
scalars defined over kites covering the cell. We show how a torque balance (commonly overlooked in implementations of the vertex model) requires each internal vertex to lie at the orthocentre of the triangle formed by neighbouring edge centroids. Torque balance also places a geometric constraint on the stress in the neighbourhood of cellular trijunctions, and requires cell edges to be orthogonal to the links of a dual network that connect neighbouring cell centres and thereby triangulate the monolayer. We show how the Airy stress function depends on cell shape when a standard energy functional is adopted, and discuss implications for computational implementations of the model.
Reconstructing ecological networks with noisy dynamics
Authors: Freilich Mara A. , Rebolledo Rolando , Corcoran Derek , Marquet Pablo A.
Published: May 2020

Ecosystems functioning is based on an intricate web of interactions among living entities. Most of these interactions are difficult to observe, especially when the diversity of interacting entities is large and they are of small size and abundance. To sidestep this limitation, it has become common to infer the network structure of ecosystems from time series of species abundance, but it is not clear how well can networks be reconstructed, especially in the presence of stochasticity that propagates through ecological networks. We evaluate the effects of intrinsic noise and network topology on the performance of different methods of inferring network structure from time-series data. Analysis of seven different four-species motifs using a stochastic model demonstrates that star-shaped motifs are differentially detected by these methods while rings are differentially constructed. The ability to reconstruct the network is unaffected by the magnitude of stochasticity in the population dynamics. Instead, interaction between the stochastic and deterministic parts of the system determines the path that the whole system takes to equilibrium and shapes the species covariance. We highlight the effects of long transients on the path to equilibrium and suggest a path forward for developing more ecologically sound statistical techniques.
The transsortative structure of networks
Authors: Ngo Shin-Chieng , Percus Allon G. , Burghardt Keith , Lerman Kristina
Published: May 2020

Network topologies can be highly non-trivial, due to the complex underlying behaviours that form them. While past research has shown that some processes on networks may be characterized by local statistics describing nodes and their neighbours, such as degree assortativity, these quantities fail to capture important sources of variation in network structure. We define a property called transsortativity that describes correlations among a node’s neighbours. Transsortativity can be systematically varied, independently of the network’s degree distribution and assortativity. Moreover, it can significantly impact the spread of contagions as well as the perceptions of neighbours, known as the majority illusion. Our work improves our ability to create and analyse more realistic models of complex networks.
Bistable probabilities: a unified framework for studying rationality and irrationality in classical and quantum games
Authors: Dehdashti Shahram , Fell Lauren , Karim Obeid Abdul , Moreira Catarina , Bruza Peter
Published: May 2020

This article presents a unified probabilistic framework that allows both rational and irrational decision-making to be theoretically investigated and simulated in classical and quantum games. Rational choice theory is a basic component of game-theoretic models, which assumes that a decision-maker chooses the best action according to their preferences. In this article, we define irrationality as a deviation from a rational choice. Bistable probabilities are proposed as a principled and straightforward means for modelling (ir)rational decision-making in games. Bistable variants of classical and quantum Prisoner’s Dilemma, Stag Hunt and Chicken are analysed in order to assess the effect of (ir)rationality on agent utility and Nash equilibria. It was found that up to three Nash equilibria exist for all three classical bistable games and maximal utility was attained when agents were rational. Up to three Nash equilibria exist for all three quantum bistable games; however, utility was shown to increase according to higher levels of agent irrationality.
From a discrete model of chemotaxis with volume-filling to a generalized Patlak–Keller–Segel model
Authors: Bubba Federica , Lorenzi Tommaso , Macfarlane Fiona R.
Published: May 2020

We present a discrete model of chemotaxis whereby cells responding to a chemoattractant are seen as individual agents whose movement is described through a set of rules that result in a biased random walk. In order to take into account possible alterations in cellular motility observed at high cell densities (i.e. volume-filling), we let the probabilities of cell movement be modulated by a decaying function of the cell density. We formally show that a general form of the celebrated Patlak–Keller–Segel (PKS) model of chemotaxis can be formally derived as the appropriate continuum limit of this discrete model. The family of steady-state solutions of such a generalized PKS model are characterized and the conditions for the emergence of spatial patterns are studied via linear stability analysis. Moreover, we carry out a systematic quantitative comparison between numerical simulations of the discrete model and numerical solutions of the corresponding PKS model, both in one and in two spatial dimensions. The results obtained indicate that there is excellent quantitative agreement between the spatial patterns produced by the two models. Finally, we numerically show that the outcomes of the two models faithfully replicate those of the classical PKS model in a suitable asymptotic regime.
The Super-Stückelberg procedure and dS in pure supergravity
Authors: Nagy Silvia , Padilla Antonio , Zavala Ivonne
Published: May 2020

Understanding de Sitter space in supergravity—and string theory—has led to an intense amount of work for more than two decades, largely motivated by the discovery of the accelerated expansion of the Universe in 1998. In this paper, we consider a non-trivial generalization of unimodular gravity to minimal

N

=
1

supergravity, which allows for de Sitter solutions without the need of introducing any matter. We formulate a superspace version of the Stückelberg procedure, which restores diffeomorphism and local supersymmetry invariance. This introduces the goldstino associated with spontaneous breaking of supersymmetry in a natural way. The cosmological constant and gravitino mass are related to the vacuum expectation value of the components of a Lagrange multiplier imposing a super-unimodularity condition.
Flexural tensegrity of segmental beams
Authors: Boni Claudio , Silvestri Marco , Royer-Carfagni Gianni
Published: May 2020

The term ‘flexural tensegrity’ applies to beam-like structures composed of segments in unilateral contact, whose integrity under flexion is provided by tendons (cables), tensioned and later anchored at the end segments. In addition to the cable tension, the constitutive response depends upon the shape of the contact surfaces between consecutive segments, identified by the corresponding pitch lines and constructed with a double couple of conjugate profiles, in order to achieve an internal constraint equivalent to a spring hinge. The response is non-local in type, because the cable elongation, and consequently the stiffness of the spring hinges, depends upon the rotations of all the segments, but this effect becomes negligible under moderate deflections. In this case, the structure can be approximated with an
elastica
in the continuum limit. Testing of prototypes, manufactured with a 3D printer, shows a very good agreement with the theoretical predictions for different designs of the spring hinges. The system, whose stiffness can be functionally graded and actively controlled, can be packaged when the cable is slack and deployed by pulling the cable at one extremity. It appears particularly suitable to build soft arms for robotics or deployable compliant booms for aerospace applications.
Stressed connections: cortisol levels following acute psychosocial stress disrupt affiliative mimicry in humans
Authors: Nitschke Jonas P. , Sunahara Cecile S. , Carr Evan W. , Winkielman Piotr , Pruessner Jens C. , Bartz Jennifer A.
Published: May 2020

Mimicry, and especially spontaneous facial mimicry, is a rudimentary element of social–emotional experience that is well-conserved across numerous species. Although such mimicry is thought to be a relatively automatic process, research indicates that contextual factors can influence mimicry, especially in humans. Here, we extend this work by investigating the effect of acute psychosocial stress on spontaneous facial mimicry. Participants performed a spontaneous facial mimicry task with facial electromyography (fEMG) at baseline and approximately one month later, following an acute psychosocial stressor (Trier Social Stress Test). Results show that the magnitude of the endocrine stress response reduced zygomaticus major reactivity, and specifically spontaneous facial mimicry for positive social stimuli (i.e. smiles). Individuals with higher levels of the stress hormone cortisol showed a more blunted fEMG response to smiles, but not to frowns. Conversely, stress had no effect on corrugator supercilii activation (i.e. frowning to frowns). These findings highlight the importance of the biological stress response system in this basic element of social–emotional experience.
Sponge symbiosis is facilitated by adaptive evolution of larval sensory and attachment structures in barnacles
Authors: Yu Meng-Chen , Dreyer Niklas , Kolbasov Gregory Aleksandrovich , Høeg Jens Thorvald , Chan Benny Kwok Kan
Published: May 2020

Symbiotic relations and range of host usage are prominent in coral reefs and crucial to the stability of such systems. In order to explain how symbiotic relations are established and evolve, we used sponge-associated barnacles to ask three questions. (1) Does larval settlement on sponge hosts require novel adaptations facilitating symbiosis? (2) How do larvae settle and start life on their hosts? (3) How has this remarkable symbiotic lifestyle involving many barnacle species evolved? We found that the larvae (cyprids) of sponge-associated barnacles show a remarkably high level of interspecific variation compared with other barnacles. We document that variation in larval attachment devices are specifically related to properties of the surface on which they attach and metamorphose. Mapping of the larval and sponge surface features onto a molecular-based phylogeny showed that sponge symbiosis evolved separately at least three times within barnacles, with the same adaptive features being found in all larvae irrespective of phylogenetic relatedness. Furthermore, the metamorphosis of two species proceeded very differently, with one species remaining superficially on the host and developing a set of white calcareous structures, the other embedding itself into the live host tissue almost immediately after settlement. We argue that such a high degree of evolutionary flexibility of barnacle larvae played an important role in the successful evolution of complex symbiotic relationships in both coral reefs and other marine systems.
Effect of urban habitat use on parasitism in mammals: a meta-analysis
Authors: Werner Courtney S. , Nunn Charles L.
Published: May 2020

Rates of urbanization are increasing globally, with consequences for the dynamics of parasites and their wildlife hosts. A small subset of mammal species have the dietary and behavioural flexibility to survive in urban settings. The changes that characterize urban ecology—including landscape transformation, modified diets and shifts in community composition—can either increase or decrease susceptibility and exposure to parasites. We used a meta-analytic approach to systematically assess differences in endoparasitism between mammals in urban and non-urban habitats. Parasite prevalence estimates in matched urban and non-urban mammal populations from 33 species were compiled from 46 published studies, and an overall effect of urban habitation on parasitism was derived after controlling for study and parasite genus. Parasite life cycle type and host order were investigated as moderators of the effect sizes. We found that parasites with complex life cycles were less prevalent in urban carnivore and primate populations than in non-urban populations. However, we found no difference in urban and non-urban prevalence for parasites in rodent and marsupial hosts, or differences in prevalence for parasites with simple life cycles in any host taxa. Our findings therefore suggest the disruption of some parasite transmission cycles in the urban ecological community.