bluuebunny/crossref_metadata_2025 huggingface dataset:
Disease Status and Pubertal Stage Predict Improved Growth in Antitumor Necrosis Factor Therapy for Pediatric Inflammatory Bowel Disease
Authors: Cameron Fiona L. , Altowati Mabrouka A. , Rogers Pamela , McGrogan Paraic , Anderson Niall , Bisset William Michael , Ahmed Syed Faisal , Wilson David C. , Russell Richard K.
Published: September 2016

Background:

Growth failure is well‐recognized in pediatric inflammatory bowel disease (PIBD; <18 years). We aimed to examine whether antitumor necrosis factor (TNF) therapy improves growth in a PIBD population‐based cohort.

Methods:

A retrospective review of all Scottish children receiving anti‐TNF (infliximab [IFX] and adalimumab [ADA]) from 2000 to 2012 was performed; height was collected at 12 months before anti‐TNF (T‐12), start (T0), and 12 (T+12) months after anti‐TNF.

Results:

Ninety‐three of 201 treated with IFX and 28 of 49 with ADA had satisfactory growth data; 66 had full pubertal data. Univariate analysis demonstrated early pubertal stages (Tanner 1–3 n = 44 vs T4–5 n = 22), disease remission, disease duration ≥2 years, and duration of IFX ≥12 months were associated with improved linear growth for IFX; for ADA only improvement was seen in Tanner 1–3. For IFX, Tanner 1–3 median Δ standard deviation scores for height (Ht SDS) −0.3 (−0.7, 0.2) at T0 changed to 0.04 (−0.5, 0.7) at T+12 (P < 0.001) versus −0.01 (−0.5, 0.9) at T0 in T4–5 changed to −0.01 (−0.4, 0.2) at T+12 (P > 0.05). For IFX disease duration ≥2 year, median Δ Ht SDS was −0.13 (−0.6, 0.3) at T0 then 0.07 (−0.3, 0.6) at T+12 (P < 0.001). Remission improved Δ Ht SDS (median Δ Ht SDS −0.14 [−0.6, 0.3] at T0 to 0.17 [−0.2, 0.7] at T+12 [P < 0.001]). Multiple regression analysis demonstrated corticosteroid usage at T0 predicted improved Δ Ht SDS at T+12 for IFX and ADA.

Conclusions:

Anti‐TNF therapy is more likely to be associated with growth improvement when used at earlier stages of puberty with remission a key growth‐promoting strategy in pediatric Crohn disease.
Outcomes of Adding Patient and Family Engagement Education to Fall Prevention Bundled Interventions
Authors: Opsahl Angela G. , Ebright Patricia , Cangany Marty , Lowder Melissa , Scott Dawn , Shaner Tamara
Published: September 2016

Nurses strive to reduce risk and ensure patient safety from falls in health care systems. Patients and their families are able to take a more active role in reducing falls. The focus of this article is on the use of bundled fall prevention interventions highlighted by a patient/family engagement educational video. The implementation of this quality improvement intervention across 2 different patient populations was successful in achieving unit benchmarks.
Seizures in Children With Severe Traumatic Brain Injury*
Authors: Bennett Kimberly Statler , DeWitt Peter E. , Harlaar Nicole , Bennett Tellen D.
Published: September 2016

Objective:

Traumatic brain injury causes substantial morbidity and mortality in children. Posttraumatic seizures may worsen outcomes after traumatic brain injury. Posttraumatic seizures risk factors are not completely understood. Our objective was to clarify posttraumatic seizures risk factors in a large cohort of children with severe traumatic brain injury.

Design:

Retrospective cohort study of a probabilistically linked dataset from the National Trauma Data Bank and the Pediatric Health Information Systems database, 2007–2010.

Setting:

Twenty-nine U.S. children’s hospitals.

Patients:

A total of 2,122 children (age, < 18 yr old at admission) with linked National Trauma Data Bank and Pediatric Health Information Systems records, severe (emergency department Glasgow Coma Scale, < 8) traumatic brain injury, hospital length of stay more than 24 hours, and nonmissing disposition.

Interventions:

None.

Measurements and Main Results:

The outcome was posttraumatic seizures, identified using validated International Classification of Diseases, 9th Revision, Clinical Modification diagnosis codes. Prespecified candidate predictors of posttraumatic seizures included age, injury mechanism, emergency department Glasgow Coma Scale, intracranial hemorrhage type, hypoxia, hypotension, and cardiac arrest. Posttraumatic seizures were diagnosed in 25.2% of children with severe traumatic brain injury. In those without abuse/assault or subdural hemorrhage, the posttraumatic seizures rate varied between 36.6% in those less than 2 years old and 16.4% in those 14–17 years old. Age, abusive mechanism, and subdural hemorrhage are each significant predictors of posttraumatic seizures. The risk of posttraumatic seizures has a complex relationship with these predictors. The estimated odds of posttraumatic seizures decrease with advancing age, odds ratio equal to 0.929 (0.905–0.954) per additional year of age with no abuse/assault and no subdural hemorrhage; odds ratio equal to 0.820 (0.730–0.922) per additional year of age when abuse and subdural hemorrhage are present. An infant with accidental traumatic brain injury and subdural hemorrhage has approximately the same estimated probability of posttraumatic seizures as an abused infant without subdural hemorrhage (47% [95% CI, 39–55%] vs 50% [95% CI, 41–58%]; p = 0.69). The triad of young age, injury by abuse/assault, and subdural hemorrhage confers the greatest estimated probability for posttraumatic seizures (60% [95% CI, 53–66%]).

Conclusions:

Posttraumatic seizures risk in children with severe traumatic brain injury is greatest with a triad of younger age, injury by abuse/assault, and subdural hemorrhage. However, posttraumatic seizures are common even in the absence of these factors.
Interleukin 1-Beta (IL-1β) Production by Innate Cells Following TLR Stimulation Correlates With TB Recurrence in ART-Treated HIV-Infected Patients
Authors: Thobakgale Christina , Naidoo Kewreshini , McKinnon Lyle R. , Werner Lise , Samsunder Natasha , Karim Salim Abdool , Ndung'u Thumbi , Altfeld Marcus , Naidoo Kogieleum
Published: September 2016

Background:

Tuberculosis (TB) remains a major cause of global morbidity and mortality, especially in the context of HIV coinfection because immunity is not completely restored following antiretroviral therapy (ART). The identification of immune correlates of risk for TB disease could help in the design of host-directed therapies and clinical management. This study aimed to identify innate immune correlates of TB recurrence in HIV+ ART-treated individuals with a history of previous successful TB treatment.

Methods:

Twelve participants with a recurrent episode of TB (cases) were matched for age, sex, time on ART, pre-ART CD4 count with 12 participants who did not develop recurrent TB in 60 months of follow-up (controls). Cryopreserved peripheral blood mononuclear cells from time-points before TB recurrence were stimulated with ligands for Toll-like receptors (TLR) including TLR-2, TLR-4, and TLR-7/8. Multicolor flow cytometry and intracellular cytokine staining were used to detect IL-1β, TNF-α, IL-12, and IP10 responses from monocytes and myeloid dendritic cells (mDCs).

Results:

Elevated production of IL-1β from monocytes following TLR-2, TLR-4, and TLR-7/8 stimulation was associated with reduced odds of TB recurrence. In contrast, production of IL-1β from both monocytes and mDCs following Bacillus Calmette–Guérin (BCG) stimulation was associated with increased odds of TB recurrence (risk of recurrence increased by 30% in monocytes and 42% in mDCs, respectively).

Conclusion:

Production of IL-1β by innate immune cells following TLR and BCG stimulations correlated with differential TB recurrence outcomes in ART-treated patients and highlights differences in host response to TB.
Brief Report: Flow Rate of Cerebrospinal Fluid Through a Spinal Needle Can Accurately Predict Intracranial Pressure in Cryptococcal Meningitis
Authors: Boyles Tom H. , Gatley Elizabeth , Wasserman Sean , Meintjes Graeme
Published: September 2016

Background:

Patients with HIV-associated cryptococcal meningitis (CM) commonly present with raised intracranial pressure (ICP). Aggressive management of raised ICP reduces mortality but requires manometers, which are unavailable in most resource-limited settings. The law of Poiseuille states that the rate of flow of liquid through a tube is directly proportional to the difference in pressure between each end, and it may be possible to indirectly determine ICP by measuring flow of CSF through a spinal needle rather than using a manometer.

Methods:

A convenience sample of CM patients requiring lumbar puncture (LP) (with 22-G spinal needle) for ICP measurement and control were enrolled. ICP was first measured using a narrow bore manometer. After removing the manometer, the number of drops of CSF flowing from the spinal needle in 15 seconds was counted.

Results:

Thirty-two patients had 89 LPs performed (range, 1–23). Fifty-four had high opening pressure with a CSF flow rate of 16–200 drops/min, and 35 had normal pressure with a CSF flow rate of 8–140 drops/min. Area under the fitted receiver operator character curve was 0.89. A flow rate cutoff to define high pressure of ≥40 drops/min correctly classified 75 of 89 LPs (accuracy 84%).

Conclusions:

It is technically feasible to indirectly estimate CSF pressure to an accuracy that is clinically useful by counting drops of CSF flowing from a spinal needle. The optimal cutoff value for defining high pressure using a standard 22-G spinal needle is ≥40 drops/min. These findings have the potential to improve CM management in resource-limited settings.
Necrotizing Autoimmune Myopathy
Authors: Carroll Matthew B. , Newkirk Michelle R. , Sumner Nathan S.
Published: September 2016

Necrotizing autoimmune myopathy (NAM) is a recently recognized entity within the spectrum of idiopathic inflammatory myopathies. Diagnosis critically rests on histopathologic demonstration of macrophage predominant myocyte destruction, with few to no lymphocytes. We report our experience with identifying and treating this subset of inflammatory myositis, highlighting the importance of muscle biopsy in diagnosis, association with statin use and malignancy, and challenges of therapy.

We present 3 cases that presented to 2 hospitals within our academic system in calendar year 2014 with acute/subacute onset of profound proximal muscle weakness and markedly elevated creatine kinase levels. All patients had been exposed to statins for varying periods. While each electromyogram (EMG) study showed changes with a diffuse inflammatory myopathy, it was not until muscle biopsy was performed when histopathologic features consistent with NAM solidified the diagnosis in all 3 cases. While high-dose glucocorticoids helped provide some degree of improvement in symptoms, none of our cases returned to their preillness baseline independent functioning. Additional immunosuppressive therapy was considered in each case but limited because of comorbidities.

These cases demonstrate the importance of pursuing muscle biopsy in all patients with proximal muscle weakness and markedly elevated creatine kinase levels. While symptoms appear consistent with polymyositis, only through muscle biopsy can the diagnosis of NAM be made. Statins have been implicated in NAM, acting through an antibody-dependent mechanism. Combination immunosuppressive therapy has been advocated, but our patient’s comorbidities precluded safe use of medications beyond glucocorticoids.
PANLAR Consensus Recommendations for the Management in Osteoarthritis of Hand, Hip, and Knee
Authors: Rillo Oscar , Riera Humberto , Acosta Carlota , Liendo Verónica , Bolaños Joyce , Monterola Ligia , Nieto Edgar , Arape Rodolfo , Franco Luisa M. , Vera Mariflor , Papasidero Silvia , Espinosa Rolando , Esquivel Jorge A. , Souto Renee , Rossi Cesar , Molina José F. , Salas José , Ballesteros Francisco , Radrigan Francisco , Guibert Marlene , Reyes Gil , Chico Araceli , Camacho Walter , Urioste Lorena , Garcia Abraham , Iraheta Isa , Gutierrez Carmen E. , Aragón Raúl , Duarte Margarita , Gonzalez Margarita , Castañeda Oswaldo , Angulo Juan , Coimbra Ibsen , Munoz-Louis Roberto , Saenz Ricardo , Vallejo Carlos , Briceño Julio , Acuña Ramón P. , De León Anibal , Reginato Anthony M. , Möller Ingrid , Caballero Carlo V. , Quintero Maritza
Published: September 2016

Objective

The objective of this consensus is to update the recommendations for the treatment of hand, hip, and knee osteoarthritis (OA) by agreeing on key propositions relating to the management of hand, hip, and knee OA, by identifying and critically appraising research evidence for the effectiveness of the treatments and by generating recommendations based on a combination of the available evidence and expert opinion of 18 countries of America.

Methods

Recommendations were developed by a group of 48 specialists of rheumatologists, members of other medical disciplines (orthopedics and physiatrists), and three patients, one for each location of OA. A systematic review of existing articles, meta-analyses, and guidelines for the management of hand, hip, and knee OA published between 2008 and January 2014 was undertaken. The scores for Level of Evidence and Grade of Recommendation were proposed and fully consented within the committee based on The American Heart Association Evidence-Based Scoring System. The level of agreement was established through a variation of Delphi technique.

Results

Both “strong” and “conditional” recommendations are given for management of hand, hip, and knee OA and nonpharmacological, pharmacological, and surgical modalities of treatment are presented according to the different levels of agreement.

Conclusions

These recommendations are based on the consensus of clinical experts from a wide range of disciplines taking available evidence into account while balancing the benefits and risks of nonpharmacological, pharmacological, and surgical treatment modalities, and incorporating their preferences and values. Different backgrounds in terms of patient education or drug availability in different countries were not evaluated but will be important.
Defining Expertise in Gynecologic Surgery: Perspectives of Expert Gynecologic Surgeons
Authors: Hardré Patricia L. , Nihira Mikio , LeClaire Edgar , Moen Michael
Published: September 2016

Objective

The aim of this study was to describe how professional expertise is defined and understood among gynecologic surgeons and what experiential factors contribute to that understanding.

Methods

Semistructured interviews with 16 experts in Female Pelvic Medicine and Reconstructive Surgery were conducted to identify how expertise in their field is defined, recognized, and assessed. Independent thematic analysis of the interview transcripts was performed by each member of the research team and then distilled and synthesized into convergent themes.

Results

Experts described surgical expertise as difficult to define but with several dominant themes including knowledge, technical skills, clinical experience, adaptability, continuous learning, communication, and professional recognition. Expertise requires judgment in applying technical skills to meet each patient's specific needs. Experts described unique ways of seeing and thinking during surgery, characterized by spatial awareness of relevant anatomy, temporal awareness of future changes, and rapidly adaptive application of their skills enabling them to do difficult tasks with fluidity, making the tasks seem easy to observers. These expert surgeons acknowledged that achieving expertise requires hard work and maintaining expertise requires continuous learning, highlighted by challenge seeking to do the most difficult tasks in their field. They also noted the importance of effective communication of their knowledge to others, which contributes to their perception as experts by colleagues in the field.

Conclusions

Surgical expertise is a complex phenomenon with several meaningful themes. Understanding the authentic nature of surgical expertise can be used to support the development of competencies and the effective mentoring of promising surgical trainees to achieve surgical expertise.
Four birds with one stone? Reparative, neuroplastic, cardiorespiratory, and metabolic benefits of aerobic exercise poststroke
Authors: Ploughman Michelle , Kelly Liam P.
Published: September 2016

Purpose of review

Converging evidence from animal models of stroke and clinical trials suggests that aerobic exercise has effects across multiple targets.

Recent findings

The subacute phase is characterized by a period of heightened neuroplasticity when aerobic exercise has the potential to optimize recovery. In animals, low intensity aerobic exercise shrinks lesion size and reduces cell death and inflammation, beginning 24 h poststroke. Also in animals, aerobic exercise upregulates brain-derived neurotrophic factor near the lesion and improves learning. In terms of neuroplastic effects, clinical trial results are less convincing and have only examined effects in chronic stroke. Stroke patients demonstrate cardiorespiratory fitness levels below the threshold required to carry out daily activities. This may contribute to a ‘neurorehabilitation ceiling’ that limits capacity to practice at a high enough frequency and intensity to promote recovery. Aerobic exercise when delivered 2–5 days per week at moderate to high intensity beginning as early as 5 days poststroke improves cardiorespiratory fitness, dyslipidemia, and glucose tolerance.

Based on the evidence discussed and applying principles of periodization commonly used to prepare athletes for competition, we have created a model of aerobic training in subacute stroke in which training is delivered in density blocks (duration × intensity) matched to recovery phases.
The role of sea ice for vascular plant dispersal in the Arctic
Authors: Alsos Inger Greve , Ehrich Dorothee , Seidenkrantz Marit-Solveig , Bennike Ole , Kirchhefer Andreas Joachim , Geirsdottir Aslaug
Published: September 2016

Sea ice has been suggested to be an important factor for dispersal of vascular plants in the Arctic. To assess its role for postglacial colonization in the North Atlantic region, we compiled data on the first Late Glacial to Holocene occurrence of vascular plant species in East Greenland, Iceland, the Faroe Islands and Svalbard. For each record, we reconstructed likely past dispersal events using data on species distributions and genetics. We compared these data to sea-ice reconstructions to evaluate the potential role of sea ice in these past colonization events and finally evaluated these results using a compilation of driftwood records as an independent source of evidence that sea ice can disperse biological material. Our results show that sea ice was, in general, more prevalent along the most likely dispersal routes at times of assumed first colonization than along other possible routes. Also, driftwood is frequently dispersed in regions that have sea ice today. Thus, sea ice may act as an important dispersal agent. Melting sea ice may hamper future dispersal of Arctic plants and thereby cause more genetic differentiation. It may also limit the northwards expansion of competing boreal species, and hence favour the persistence of Arctic species.
Timing of ice retreat alters seabird abundances and distributions in the southeast Bering Sea
Authors: Renner Martin , Salo Sigrid , Eisner Lisa B. , Ressler Patrick H. , Ladd Carol , Kuletz Kathy J. , Santora Jarrod A. , Piatt John F. , Drew Gary S. , Hunt George L.
Published: September 2016

Timing of spring sea-ice retreat shapes the southeast Bering Sea food web. We compared summer seabird densities and average bathymetry depth distributions between years with early (typically warm) and late (typically cold) ice retreat. Averaged over all seabird species, densities in early-ice-retreat-years were 10.1% (95% CI: 1.1–47.9%) of that in late-ice-retreat-years. In early-ice-retreat-years, surface-foraging species had increased numbers over the middle shelf (50–150 m) and reduced numbers over the shelf slope (200–500 m). Pursuit-diving seabirds showed a less clear trend. Euphausiids and the copepod
Calanus marshallae/glacialis
were 2.4 and 18.1 times less abundant in early-ice-retreat-years, respectively, whereas age-0 walleye pollock
Gadus chalcogrammus
near-surface densities were 51× higher in early-ice-retreat-years. Our results suggest a mechanistic understanding of how present and future changes in sea-ice-retreat timing may affect top predators like seabirds in the southeastern Bering Sea.
Sex-specific, inverted rhythms of breeding-site attendance in an Arctic seabird
Authors: Huffeldt Nicholas Per , Merkel Flemming R.
Published: September 2016

In contrast to daily rhythms that are common in the presence of the geophysical light–dark cycle, organisms at polar latitudes exhibit many diel activity patterns during natural periods of continuous solar light or darkness (polar day and night, respectively), from 24 h rhythms to arrhythmicity. In Arctic Greenland (73.7° N, 56.6° W) during polar day, we observed breeding-site attendance rhythms of thick-billed murres (
Uria lomvia
;
n
= 21 pairs), a charadriiform seabird, which provide biparental care at the colony. We found that
U. lomvia
egg-incubation and chick-brooding attendance is rhythmic and synchronized to the geophysical day (mean period length [rhythm duration] ± 95% confidence interval = 24.13 ± 0.52 h). Individual pair members had temporally segregated, sex-specific colony-attendance rhythms that were opposite (inverted) to each other, and these sex-specific rhythms were prominent at the population level. Our results provide a basis for investigating circadian systems at polar latitudes and sex-specific parental-care strategies.
Decreased small mammal and on-host tick abundance in association with invasive red imported fire ants (
Solenopsis invicta
)
Authors: Castellanos Adrian A. , Medeiros Matthew C. I. , Hamer Gabriel L. , Morrow Michael E. , Eubanks Micky D. , Teel Pete D. , Hamer Sarah A. , Light Jessica E.
Published: September 2016

Invasive species may impact pathogen transmission by altering the distributions and interactions among native vertebrate reservoir hosts and arthropod vectors. Here, we examined the direct and indirect effects of the red imported fire ant (
Solenopsis invicta
) on the native tick, small mammal and pathogen community in southeast Texas. Using a replicated large-scale field manipulation study, we show that small mammals were more abundant on treatment plots where
S. invicta
populations were experimentally reduced. Our analysis of ticks on small mammal hosts demonstrated a threefold increase in the ticks caught per unit effort on treatment relative to control plots, and elevated tick loads (a 27-fold increase) on one common rodent species
.
We detected only one known human pathogen (
Rickettsia parkeri
), present in 1.4% of larvae and 6.7% of nymph on-host
Amblyomma maculatum
samples but with no significant difference between treatment and control plots. Given that host and vector population dynamics are key drivers of pathogen transmission, the reduced small mammal and tick abundance associated with
S. invicta
may alter pathogen transmission dynamics over broader spatial scales.
The fragmentation of Pangaea and Mesozoic terrestrial vertebrate biodiversity
Authors: Vavrek Matthew J.
Published: September 2016

During the Mesozoic (242–66 million years ago), terrestrial regions underwent a massive shift in their size, position and connectivity. At the beginning of the era, the land masses were joined into a single supercontinent called Pangaea. However, by the end of the Mesozoic, terrestrial regions had become highly fragmented, both owing to the drifting apart of the continental plates and the extremely high sea levels that flooded and divided many regions. How terrestrial biodiversity was affected by this fragmentation and large-scale flooding of the Earth's landmasses is uncertain. Based on a model using the species–area relationship (SAR), terrestrial vertebrate biodiversity would be expected to nearly double through the Mesozoic owing to continental fragmentation, despite a decrease of 24% in total terrestrial area. Previous studies of Mesozoic vertebrates have generally found increases in terrestrial diversity towards the end of the era, although these increases are often attributed to intrinsic or climatic factors. Instead, continental fragmentation over this time may largely explain any observed increase in terrestrial biodiversity. This study demonstrates the importance that non-intrinsic effects can have on the taxonomic success of a group, and the importance of geography to understanding past biodiversity.
Strength of forelimb lateralization predicts motor errors in an insect
Authors: Bell Adrian T. A. , Niven Jeremy E.
Published: September 2016

Lateralized behaviours are widespread in both vertebrates and invertebrates, suggesting that lateralization is advantageous. Yet evidence demonstrating proximate or ultimate advantages remains scarce, particularly in invertebrates or in species with individual-level lateralization. Desert locusts (Schistocerca gregaria) are biased in the forelimb they use to perform targeted reaching across a gap. The forelimb and strength of this bias differed among individuals, indicative of individual-level lateralization. Here we show that strongly biased locusts perform better during gap-crossing, making fewer errors with their preferred forelimb. The number of targeting errors locusts make negatively correlates with the strength of forelimb lateralization. This provides evidence that stronger lateralization confers an advantage in terms of improved motor control in an invertebrate with individual-level lateralization.
Altered trait variability in response to size-selective mortality
Authors: Uusi-Heikkilä Silva , Lindström Kai , Parre Noora , Arlinghaus Robert , Alós Josep , Kuparinen Anna
Published: September 2016

Changes in trait variability owing to size-selective harvesting have received little attention in comparison with changes in mean trait values, perhaps because of the expectation that phenotypic variability should generally be eroded by directional selection typical for fishing and hunting. We show, however, that directional selection, in particular for large body size, leads to increased body-size variation in experimentally harvested zebrafish (
Danio rerio
) populations exposed to two alternative feeding environments: ad libitum and temporarily restricted food availability. Trait variation may influence population adaptivity, stability and resilience. Therefore, rather than exerting selection pressures that favour small individuals, our results stress the importance of protecting large ones, as they can harbour a great amount of variation within a population, to manage fish stocks sustainably.
Sea turtle symbiosis facilitates social monogamy in oceanic crabs via refuge size
Authors: Pfaller Joseph B. , Gil Michael A.
Published: September 2016

The capacity for resource monopolization by individuals often dictates the size and composition of animal groups, and ultimately, the adoption of mating strategies. For refuge-dwelling animals, the ability (or inability) of individuals to monopolize refuges should depend on the relative size of the refuge. In theory, groups should be larger and more inclusive when refuges are large, and smaller and more exclusive when refuges are small, regardless of refuge type. We test this prediction by comparing the size and composition of groups of oceanic crabs (
Planes minutus
) living on plastic flotsam and loggerhead sea turtles. We found that (i) surface area of refuges (barnacle colonies on flotsam and supracaudal space on turtles) is a better predictor of crab number than total surface area and (ii) flotsam and turtles with similar refuge surface area host a similar number (1–2) and composition (adult male–female pairs) of crabs. These results indicate that group size and composition of refuge-dwelling animals are modulated by refuge size and the capacity for refuge monopolization. Moreover, these results suggest that sea turtle symbiosis facilitates social monogamy in oceanic crabs, providing insights into how symbiosis can promote specific mating strategies.
A model for the effects of germanium on silica biomineralization in choanoflagellates
Authors: Marron Alan O. , Chappell Helen , Ratcliffe Sarah , Goldstein Raymond E.
Published: September 2016

Silica biomineralization is a widespread phenomenon of major biotechnological interest. Modifying biosilica with substances like germanium (Ge) can confer useful new properties, although exposure to high levels of Ge disrupts normal biosilicification. No clear mechanism explains why this disruption occurs. Here, we study the effect of Ge on loricate choanoflagellates, a group of protists that construct a species-specific extracellular lorica from multiple siliceous costal strips. High Ge exposures were toxic, whereas lower Ge exposures produced cells with incomplete or absent loricae. These effects can be ameliorated by restoring the germanium : silicon ratio, as observed in other biosilicifying organisms. We developed simulations of how Ge interacts with polymerizing silica. In our models, Ge is readily incorporated at the ends of silica forming from silicic acid condensation, but this prevents further silica polymerization. Our ‘Ge-capping’ model is supported by observations from loricate choanoflagellates. Ge exposure terminates costal strip synthesis and lorica formation, resulting in disruption to cytokinesis and fatal build-up of silicic acid. Applying the Ge-capping model to other siliceous organisms explains the general toxicity of Ge and identifies potential protective responses in metalloid uptake and sensing. This can improve the design of new silica biomaterials, and further our understanding of silicon metabolism.
Using collision cones to assess biological deconfliction methods
Authors: Brace Natalie L. , Hedrick Tyson L. , Theriault Diane H. , Fuller Nathan W. , Wu Zheng , Betke Margrit , Parrish Julia K. , Grünbaum Daniel , Morgansen Kristi A.
Published: September 2016

Biological systems consistently outperform autonomous systems governed by engineered algorithms in their ability to reactively avoid collisions. To better understand this discrepancy, a collision avoidance algorithm was applied to frames of digitized video trajectory data from bats, swallows and fish (Myotis velifer,Petrochelidon pyrrhonotaandDanio aequipinnatus). Information available from visual cues, specifically relative position and velocity, was provided to the algorithm which used this information to define collision cones that allowed the algorithm to find a safe velocity requiring minimal deviation from the original velocity. The subset of obstacles provided to the algorithm was determined by the animal's sensing range in terms of metric and topological distance. The algorithmic calculated velocities showed good agreement with observed biological velocities, indicating that the algorithm was an informative basis for comparison with the three species and could potentially be improved for engineered applications with further study.
Human and avian running on uneven ground: a model-based comparison
Authors: Müller R. , Birn-Jeffery A. V. , Blum Y.
Published: September 2016

Birds and humans are successful bipedal runners, who have individually evolved bipedalism, but the extent of the similarities and differences of their bipedal locomotion is unknown. In turn, the anatomical differences of their locomotor systems complicate direct comparisons. However, a simplifying mechanical model, such as the conservative spring–mass model, can be used to describe both avian and human running and thus, provides a way to compare the locomotor strategies that birds and humans use when running on level and uneven ground. Although humans run with significantly steeper leg angles at touchdown and stiffer legs when compared with cursorial ground birds, swing-leg adaptations (leg angle and leg length kinematics) used by birds and humans while running appear similar across all types of uneven ground. Nevertheless, owing to morphological restrictions, the crouched avian leg has a greater range of leg angle and leg length adaptations when coping with drops and downward steps than the straight human leg. On the other hand, the straight human leg seems to use leg stiffness adaptation when coping with obstacles and upward steps unlike the crouched avian leg posture.
The natural selection of bad science
Authors: Smaldino Paul E. , McElreath Richard
Published: September 2016

Poor research design and data analysis encourage false-positive findings. Such poor methods persist despite perennial calls for improvement, suggesting that they result from something more than just misunderstanding. The persistence of poor methods results partly from incentives that favour them, leading to the natural selection of bad science. This dynamic requires no conscious strategizing—no deliberate cheating nor loafing—by scientists, only that publication is a principal factor for career advancement. Some normative methods of analysis have almost certainly been selected to further publication instead of discovery. In order to improve the culture of science, a shift must be made away from correcting misunderstandings and towards rewarding understanding. We support this argument with empirical evidence and computational modelling. We first present a 60-year meta-analysis of statistical power in the behavioural sciences and show that power has not improved despite repeated demonstrations of the necessity of increasing power. To demonstrate the logical consequences of structural incentives, we then present a dynamic model of scientific communities in which competing laboratories investigate novel or previously published hypotheses using culturally transmitted research methods. As in the real world, successful labs produce more ‘progeny,’ such that their methods are more often copied and their students are more likely to start labs of their own. Selection for high output leads to poorer methods and increasingly high false discovery rates. We additionally show that replication slows but does not stop the process of methodological deterioration. Improving the quality of research requires change at the institutional level.
The first iguanian lizard from the Mesozoic of Africa
Authors: Apesteguía Sebastián , Daza Juan D. , Simões Tiago R. , Rage Jean Claude
Published: September 2016

The fossil record shows that iguanian lizards were widely distributed during the Late Cretaceous. However, the biogeographic history and early evolution of one of its most diverse and peculiar clades (acrodontans) remain poorly known. Here, we present the first Mesozoic acrodontan from Africa, which also represents the oldest iguanian lizard from that continent. The new taxon comes from the Kem Kem Beds in Morocco (Cenomanian, Late Cretaceous) and is based on a partial lower jaw. The new taxon presents a number of features that are found only among acrodontan lizards and shares greatest similarities with uromastycines, specifically. In a combined evidence phylogenetic dataset comprehensive of all major acrodontan lineages using multiple tree inference methods (traditional and implied weighting maximum-parsimony, and Bayesian inference), we found support for the placement of the new species within uromastycines, along withGueragama sulamericana(Late Cretaceous of Brazil). The new fossil supports the previously hypothesized widespread geographical distribution of acrodontans in Gondwana during the Mesozoic. Additionally, it provides the first fossil evidence of uromastycines in the Cretaceous, and the ancestry of acrodontan iguanians in Africa.
Unifying dynamical and structural stability of equilibria
Authors: Arnoldi Jean-François , Haegeman Bart
Published: September 2016

We exhibit a fundamental relationship between measures of dynamical and structural stability of linear dynamical systems—e.g. linearized models in the vicinity of equilibria. We show that dynamical stability, quantified via the response to external perturbations (i.e. perturbation of dynamical variables), coincides with the minimal internal perturbation (i.e. perturbations of interactions between variables) able to render the system unstable. First, by reformulating a result of control theory, we explain that harmonic external perturbations reflect the spectral sensitivity of the Jacobian matrix at the equilibrium, with respect to constant changes of its coefficients. However, for this equivalence to hold, imaginary changes of the Jacobian’s coefficients have to be allowed. The connection with dynamical stability is thus lost for real dynamical systems. We show that this issue can be avoided, thus recovering the fundamental link between dynamical and structural stability, by considering stochastic noise as external and internal perturbations. More precisely, we demonstrate that a linear system’s response to white-noise perturbations directly reflects the intensity of internal white-noise disturbance that it can accommodate before becoming stochastically unstable.
Unsteady solute dispersion in non-Newtonian fluid flow in a tube with wall absorption
Authors: Rana Jyotirmoy , Murthy P. V. S. N.
Published: September 2016

The theory of miscible dispersion in a straight circular pipe with interphase mass transfer that was investigated by Sankarasubramanian & Gill (1973
Proc. R. Soc. Lond. A
333, 115–132. (
doi:10.1098/rspa.1973.0051
); 1974
Proc. R. Soc. Lond. A
341, 407–408. (
doi:10.1098/rspa.1974.0195
)) in Newtonian fluid flow is extended by considering various non-Newtonian fluid models, such as the Casson (Rana & Murthy 2016
J. Fluid Mech.
793, 877–914. (
doi:10.1017/jfm.2016.155
)), Carreau and Carreau–Yasuda models. These models are useful to investigate the solute dispersion in blood flow. The three effective transport coefficients, i.e. exchange, convection and dispersion coefficients, are evaluated to analyse the dispersion process of solute. The convection and dispersion coefficients are determined asymptotically at large time which is sufficient to understand the nature of the solute dispersion process in a tube. The axial mean concentration is analysed, using the asymptotic expressions for these three coefficients. The effect of the wall absorption parameter, Weissenberg number, power-law index, Yasuda parameter and Peclet number on the dispersion process is discussed clearly in this study. A comparative study of the solute dispersion among the Newtonian and all other non-Newtonian models is presented. At low shear rate, it is observed that Carreau fluid behaves like Newtonian fluid, whereas the other fluids exhibit significant differences during the solute dispersion. This study may be applicable to understand the dispersion process of drugs in the blood stream.
Synergistic impacts of habitat loss and fragmentation on model ecosystems
Authors: Bartlett Lewis J. , Newbold Tim , Purves Drew W. , Tittensor Derek P. , Harfoot Michael B. J.
Published: September 2016

Habitat loss and fragmentation are major threats to biodiversity, yet separating their effects is challenging. We use a multi-trophic, trait-based, and spatially explicit general ecosystem model to examine the independent and synergistic effects of these processes on ecosystem structure. We manipulated habitat by removing plant biomass in varying spatial extents, intensities, and configurations. We found that emergent synergistic interactions of loss and fragmentation are major determinants of ecosystem response, including population declines and trophic pyramid shifts. Furthermore, trait-mediated interactions, such as a disproportionate sensitivity of large-sized organisms to fragmentation, produce significant effects in shaping responses. We also show that top-down regulation mitigates the effects of land use on plant biomass loss, suggesting that models lacking these interactions—including most carbon stock models—may not adequately capture land-use change impacts. Our results have important implications for understanding ecosystem responses to environmental change, and assessing the impacts of habitat fragmentation.
Prenatal stress effects in a wild, long-lived primate: predictive adaptive responses in an unpredictable environment
Authors: Berghänel Andreas , Heistermann Michael , Schülke Oliver , Ostner Julia
Published: September 2016

Prenatal maternal stress affects offspring phenotype in numerous species including humans, but it is debated whether these effects are evolutionarily adaptive. Relating stress to adverse conditions, current explanations invoke either short-term developmental constraints on offspring phenotype resulting in decelerated growth to avoid starvation, or long-term predictive adaptive responses (PARs) resulting in accelerated growth and reproduction in response to reduced life expectancies. Two PAR subtypes were proposed, acting either on predicted internal somatic states or predicted external environmental conditions, but because both affect phenotypes similarly, they are largely indistinguishable. Only external (not internal) PARs rely on high environmental stability particularly in long-lived species. We report on a crucial test case in a wild long-lived mammal, the Assamese macaque (
Macaca assamensis
), which evolved and lives in an unpredictable environment where external PARs are probably not advantageous. We quantified food availability, growth, motor skills, maternal caretaking style and maternal physiological stress from faecal glucocorticoid measures. Prenatal maternal stress was negatively correlated to prenatal food availability and led to accelerated offspring growth accompanied by decelerated motor skill acquisition and reduced immune function. These results support the ‘internal PAR’ theory, which stresses the role of stable adverse internal somatic states rather than stable external environments.
Climate change relaxes the time constraints for late-born offspring in a long-distance migrant
Authors: Tomotani Barbara M. , Gienapp Phillip , Beersma Domien G. M. , Visser Marcel E.
Published: September 2016

Animals in seasonal environments need to fit their annual-cycle stages, such as moult and migration, in a tight schedule. Climate change affects the phenology of organisms and causes advancements in timing of these annual-cycle stages but not necessarily at the same rates. For migratory birds, this can lead to more severe or more relaxed time constraints in the time from fledging to migration, depending on the relative shifts of the different stages. We tested how a shift in hatch date, which has advanced due to climate change, impacts the organization of the birds' whole annual cycle. We experimentally advanced and delayed the hatch date of pied flycatcher chicks in the field and then measured the timing of their annual-cycle stages in a controlled laboratory environment. Hatch date affected the timing of moult and pre-migratory fattening, but not migration. Early-born birds hence had a longer time to fatten up than late-born ones; the latter reduced their interval between onset of fattening and migration to be able to migrate at the same time as the early-born birds. This difference in time constraints for early- and late-born individuals may explain why early-born offspring have a higher probability to recruit as a breeding bird. Climate change-associated advancements of avian egg-lay dates, which in turn advances hatch dates, can thus reduce the negative fitness consequences of reproducing late, thereby reducing the selection for early egg-laying migratory birds.
Demographic mechanisms underpinning genetic assimilation of remnant groups of a large carnivore
Authors: Mikle Nate , Graves Tabitha A. , Kovach Ryan , Kendall Katherine C. , Macleod Amy C.
Published: September 2016

Current range expansions of large terrestrial carnivores are occurring following human-induced range contraction. Contractions are often incomplete, leaving small remnant groups in refugia throughout the former range. Little is known about the underlying ecological and evolutionary processes that influence how remnant groups are affected during range expansion. We used data from a spatially explicit, long-term genetic sampling effort of grizzly bears (Ursus arctos) in the Northern Continental Divide Ecosystem (NCDE), USA, to identify the demographic processes underlying spatial and temporal patterns of genetic diversity. We conducted parentage analysis to evaluate how reproductive success and dispersal contribute to spatio-temporal patterns of genetic diversity in remnant groups of grizzly bears existing in the southwestern (SW), southeastern (SE) and east-central (EC) regions of the NCDE. A few reproductively dominant individuals and local inbreeding caused low genetic diversity in peripheral regions that may have persisted for multiple generations before eroding rapidly (approx. one generation) during population expansion. Our results highlight that individual-level genetic and reproductive dynamics play critical roles during genetic assimilation, and show that spatial patterns of genetic diversity on the leading edge of an expansion may result from historical demographic patterns that are highly ephemeral.
Novel energy-saving strategies to multiple stressors in birds: the ultradian regulation of body temperature
Authors: Tattersall Glenn J. , Roussel Damien , Voituron Yann , Teulier Loïc
Published: September 2016

This study aimed to examine thermoregulatory responses in birds facing two commonly experienced stressors, cold and fasting. Logging devices allowing long-term and precise access to internal body temperature were placed within the gizzards of ducklings acclimated to cold (CA) (5°C) or thermoneutrality (TN) (25°C). The animals were then examined under three equal 4-day periods: ad libitum feeding, fasting and re-feeding. Through the analysis of daily as well as short-term, or ultradian, variations of body temperature, we showed that while ducklings at TN show only a modest decline in daily thermoregulatory parameters when fasted, they exhibit reduced surface temperatures from key sites of vascular heat exchange during fasting. The CA birds, on the other hand, significantly reduced their short-term variations of body temperature while increasing long-term variability when fasting. This phenomenon would allow the CA birds to reduce the energetic cost of body temperature maintenance under fasting. By analysing ultradian regulation of body temperature, we describe a means by which an endotherm appears to lower thermoregulatory costs in response to the combined stressors of cold and fasting.
Probiotic treatment restores protection against lethal fungal infection lost during amphibian captivity
Authors: Kueneman Jordan G. , Woodhams Douglas C. , Harris Reid , Archer Holly M. , Knight Rob , McKenzie Valerie J.
Published: September 2016

Host-associated microbiomes perform many beneficial functions including resisting pathogens and training the immune system. Here, we show that amphibians developing in captivity lose substantial skin bacterial diversity, primarily due to reduced ongoing input from environmental sources. We combined studies of wild and captive amphibians with a database of over 1 000 strains that allows us to examine antifungal function of the skin microbiome. We tracked skin bacterial communities of 62 endangered boreal toads,
Anaxyrus boreas
, across 18 time points, four probiotic treatments, and two exposures to the lethal fungal pathogen
Batrachochytrium dendrobatidis
(
Bd
) in captivity, and compared these to 33 samples collected from wild populations at the same life stage. As the amphibians in captivity lost the
Bd
-inhibitory bacteria through time, the proportion of individuals exposed to
Bd
that became infected rose from 33% to 100% in subsequent exposures. Inoculations of the
Bd
-inhibitory probiotic
Janthinobacterium lividum
resulted in a 40% increase in survival during the second
Bd
challenge, indicating that the effect of microbiome depletion was reversible by restoring
Bd
-inhibitory bacteria. Taken together, this study highlights the functional role of ongoing environmental inputs of skin-associated bacteria in mitigating a devastating amphibian pathogen, and that long-term captivity decreases this defensive function.