bluuebunny/crossref_metadata_2025 huggingface dataset:
Reference Values of Reticulocyte Hemoglobin Content in Healthy Adolescents
Authors: Ibáñez-Alcalde María M. , Vázquez-López María Á. , Ruíz-Sánchez Ana M. , Lendínez-Molinos Francisco J. , Galera-Martínez Rafael , Bonillo-Perales Antonio , Parrón-Carreño Tesifón
Published: March 2018

Assessing iron status in a pediatric population is not easy, as it is based on parameters that undergo physiological variations in childhood and adolescence. Analysis of the reticulocyte hemoglobin content (CHr) to screen for iron deficiency may increase the accuracy of diagnosis, but, to date, reference values in healthy adolescents have not been adequately determined. A cross-sectional study was conducted on a population-based representative sample in the city of Almería (Spain), with 253 healthy non–iron-deficient (ID) subjects, aged 12 to 16 years. The mean CHr value was 31.6±1.3 pg. The CHr 2.5 percentile was 28.7 pg. There were no significant differences as regards age or sex. In the multivariate linear regression analysis, sex did not influence the variability of CHr, but it was related to age. CHr was influenced by hemoglobin and the Mentzer index, as well as by functional iron indicators such as erythrocyte protoporphyrin and serum transferrin receptor. These independent variables predicted two thirds of the variability in healthy adolescents (R
2=0.55). This study provides CHr reference ranges in healthy adolescents for use in clinical practice for the early detection of ID states. In populations with similar sociodemographic characteristics, values above the 2.5 percentile rule out ID, as values under the 2.5 percentile could be suggestive of functional ID.
The effect of sulfur-containing amino acids on the biosynthesis of lincomycin
Authors: Yang Jing , Ye Ruifang , Pang Xuewei , Zhang Hongzhou , Liu Yan
Published: March 2018

Lincomycin, a clinically important antibiotic for the treatment of diseases caused by Gram-positive bacteria, is formed by a bifurcated biosynthetic pathway. The latest research reported that two low-molecular-weight thiols, mycothiol and ergothioneine were discovered in the sulfur of lincomycin. The coupling of two bacterial thiols could be biosynthesized by histidine, cysteine and methionine, which indicates the relationship between the three amino acids and the enhancement of the two thiols in the lincomycin biosynthesis. In 15-l stirred bioreactor, methionine and the combination of the three amino acids were added, and the lincomycin productions were increased by 24.6 and 47.5% compared with control (6051 μ/ml). Along with last S-methylation gene lmbG, the key biosynthesis genes of mycothiol and ergothioneine and the cyclic regeneration genes in lincomycin biosynthesis, mshA, egtD, lmbT, lmbV and lmbE, were analyzed by real-time-quantitative PCR, and the results shown the expression levels of these genes were higher than the control.
Motor Dysfunction as a Risk Factor for Conversion to Psychosis Independent of Medication Use in a Psychosis-Risk Cohort
Authors: Masucci Michael D. , Lister Amanda , Corcoran Cheryl M. , Brucato Gary , Girgis Ragy R.
Published: March 2018

The Structured Interview for Psychosis-Risk Syndromes (SIPS) contains criteria for the Attenuated Positive Symptom Syndrome (APSS), a period of subthreshold positive symptoms that predates full-blown psychosis. Motor abnormalities are often associated with these symptoms but have not been adequately studied. We assessed a diverse sample of 192 APSS participants (27.1% female; 47.9% white; mean age = 20.03 years) for motor dysfunction (SIPS G.3. score) at baseline and conversion to psychosis every 3 months for up to 2 years. Fifty-nine (30.7%) participants converted to psychosis. Baseline G.3. score was significantly higher among converters than nonconverters (mean difference = 0.66; t[95.929] = 2.579, p < 0.05). No significant differences in baseline G.3. were found between demographic groups or those with differential medication use. These results point to the use of G.3. as a potential predictor of psychosis among APSS individuals and potentially implicate the shared biological underpinnings of motor dysfunction in the APSS and full-blown psychotic illnesses.
Human Lacrimal Production Rates from Modified Schirmer-Tear Test
Authors: Li Songhao , Kim Young Hyun , Li Wing , Lin Meng C. , Radke Clayton J.
Published: March 2018

SIGNIFICANCE

A simple methodology is presented to quantify basal tear production with a modified Schirmer-tear test.

PURPOSE

We introduce a simple clinical procedure to measure quantitative basal tear-production flowrates, Q

L
, from a modified Schirmer-tear test (STT).

METHODS

Eight healthy subjects aged at least 18 years underwent modified STTs on both eyes for two visits each. Schirmer strips were sheathed with transparent tape before insertion. Topical anesthetic minimized reflex tearing. Wetting lengths were measured every 30 s for 5 min; Q

L
was calculated from the linear slope of wetting length versus time. Determination of Q

L
requires mass–balance equations on the tear prism and Schirmer strip with strip imbibition kinetics obeying Darcy and Young–Laplace laws.

RESULTS

Basal tear production rates varied from essentially 0 to about 2 μl/min. With some exceptions, right and left eyes showed similar tear production rates.

CONCLUSIONS

By following the modified STT, Q

L
is established with minimal additional effort over a standard Schirmer test. We predict and observe four different subtypes of imbibition kinetics depending on how short or long the time is for first appearance of the wetting front and on how fast or slow is tear production. For slow lacrimal production rates, the standard 5-min wetting length does not correlate with basal tear production.
The ipRGC-Driven Pupil Response with Light Exposure, Refractive Error, and Sleep
Authors: Abbott Kaleb S. , Queener Hope M. , Ostrin Lisa A.
Published: March 2018

SIGNIFICANCE

We investigated links between the intrinsically photosensitive retinal ganglion cells, light exposure, refractive error, and sleep. Results showed that morning melatonin was associated with light exposure, with modest differences in sleep quality between myopes and emmetropes. Findings suggest a complex relationship between light exposure and these physiological processes.

PURPOSE

Intrinsically photosensitive retinal ganglion cells (ipRGCs) signal environmental light, with pathways to the midbrain to control pupil size and circadian rhythm. Evidence suggests that light exposure plays a role in refractive error development. Our goal was to investigate links between light exposure, ipRGCs, refractive error, and sleep.

METHODS

Fifty subjects, aged 17–40, participated (19 emmetropes and 31 myopes). A subset of subjects (n = 24) wore an Actiwatch Spectrum for 1 week. The Pittsburgh Sleep Quality Index (PSQI) was administered, and saliva samples were collected for melatonin analysis. The post-illumination pupil response (PIPR) to 1 s and 5 s long- and short-wavelength stimuli was measured. Pupil metrics included the 6 s and 30 s PIPR and early and late area under the curve.

RESULTS

Subjects spent 104.8 ± 46.6 min outdoors per day over the previous week. Morning melatonin concentration (6.9 ± 3.5 pg/ml) was significantly associated with time outdoors and objectively measured light exposure (P= .01 and .002, respectively). Pupil metrics were not significantly associated with light exposure or refractive error. PSQI scores indicated good sleep quality for emmetropes (score 4.2 ± 2.3) and poor sleep quality for myopes (5.6 ± 2.2,P= .04).

CONCLUSIONS

We found that light exposure and time outdoors influenced morning melatonin concentration. No differences in melatonin or the ipRGC-driven pupil response were observed between refractive error groups, although myopes exhibited poor sleep quality compared to emmetropes. Findings suggest that a complex relationship between light exposure, ipRGCs, refractive error, and sleep exists.
Probabilistic Matching of Deidentified Data From a Trauma Registry and a Traumatic Brain Injury Model System Center
Authors: Kumar Raj G. , Wang Zhensheng , Kesinger Matthew R. , Newman Mark , Huynh Toan T. , Niemeier Janet P. , Sperry Jason L. , Wagner Amy K.
Published: March 2018

In a previous study, individuals from a single Traumatic Brain Injury Model Systems and trauma center were matched using a novel probabilistic matching algorithm. The Traumatic Brain Injury Model Systems is a multicenter prospective cohort study containing more than 14,000 participants with traumatic brain injury, following them from inpatient rehabilitation to the community over the remainder of their lifetime. The National Trauma Databank is the largest aggregation of trauma data in the United States, including more than 6 million records. Linking these two databases offers a broad range of opportunities to explore research questions not otherwise possible. Our objective was to refine and validate the previous protocol at another independent center. An algorithm generation and validation data set were created, and potential matches were blocked by age, sex, and year of injury; total probabilistic weight was calculated based on of 12 common data fields. Validity metrics were calculated using a minimum probabilistic weight of 3. The positive predictive value was 98.2% and 97.4% and sensitivity was 74.1% and 76.3%, in the algorithm generation and validation set, respectively. These metrics were similar to the previous study. Future work will apply the refined probabilistic matching algorithm to the Traumatic Brain Injury Model Systems and the National Trauma Databank to generate a merged data set for clinical traumatic brain injury research use.
A New Comorbidity in Female Patients With Ankylosing Spondylitis
Authors: Çağlayan Mehmet , Oktayoğlu Pelin , Ağaçayak Elif , Dagli Abdullah Zübeyir , Okçu Mehmet , Nas Kemal
Published: March 2018

Aim

The aim of this study was to investigate whether increased intra-abdominal pressure caused by pelvic inflammation and frequent use of the Valsalva maneuver increases the incidence of pelvic organ prolapse (POP) among female patients with ankylosing spondylitis (AS).

Methods

Thirty-nine patients diagnosed as having AS through the use of the modified New York criteria, 47 patients with chronic low-back pain (CLBP), and 38 healthy controls (HCs) were included in this study. All the patients and the HCs underwent thorough physical and gynecological examinations. Pelvic organ prolapse was graded blindly by a gynecologist. Presence or absence of cystocele (CS), rectocele (RC), and uterine prolapse (UP) was noted.

Results

The incidences of CS, RC, and UD were significantly higher among the AS patients compared with the HCs (p= 0.001, 0.026, and 0002, respectively). The incidences of CS (p= 0.042) and UD (p= 0.017) were significantly higher among the AS patients compared with the CLBP patients.

Conclusions

The incidence of POP is higher among patients with AS compared with normal population. These patients should be questioned about the symptoms of POP and recommended, if necessary, regular gynecological examinations, as well as specific exercises including those targeting AS.
Evaluation of Learned Helplessness, Perceived Self-efficacy, and Functional Capacity in Patients With Fibromyalgia and Rheumatoid Arthritis
Authors: Moyano Sebastián , Scolnik Marina , Vergara Facundo , García María Victoria , Sabelli Mirtha Rosa , Rosa Javier Eduardo , Catoggio Luis José , Soriano Enrique Roberto
Published: March 2018

Objectives

The aims of this study were to compare learned helplessness (LH) and perceived self-efficacy (SE) in patients with fibromyalgia (FM) and rheumatoid arthritis (RA) and to assess their correlation with functional disability, level of perceived pain, and fatigue.

Methods

This multicenter, cross-sectional study included consecutive patients (aged ≥18 years) with RA, according to the 2010 American College of Rheumatology/European League Against Rheumatism criteria, and FM, according to 2010 American College of Rheumatology criteria. Learned helplessness was measured by the Rheumatology Attitude Index, Spanish version; SE with the Arthritis Self-efficacy Scale, Spanish version; functional capacity with the Health Assessment Questionnaire (HAQ), Argentine version; depression with Center for Epidemiological Studies–Depression Scale 7-item version and perceived pain and fatigue by the visual analog scale. Disease activity was measured by the Clinical Disease Activity Index (CDAI) and disease impact with the Fibromyalgia Impact Questionnaire (FIQ).

Results

A total of 215 patients, 100 with FM and 115 with RA, were included. Mean age was 59 (SD, 14) years and 58 (SD, 13) years for FM and RA, patients respectively. Whereas LH and depression were significantly higher, SE was significantly lower in FM patients. We found a positive correlation between LH and HAQ, pain, depression, fatigue, FIQ, and CDAI in FM and RA patients. We observed a negative correlation between SE and HAQ, pain, depression, fatigue, FIQ (FM), and CDAI (RA) in both groups.

Conclusions

Both LH and SE correlate significantly with functional capacity, perceived pain, disease activity, and disease impact in RA and FM patients. Learned helplessness was higher in patients with active disease or high disease impact, as opposed to those in remission or with low disease impact, and the reverse was true for SE. Patients with FM had significantly more LH, pain, fatigue, and depression and less SE compared with those with RA.
Resolution of Diplopia in Late Repair of Enophthalmos Following Facial Trauma
Authors: Liu Edward H. , Najarali Zainab , Farrokhyar Forough , Banfield Laura , McRae Mark
Published: March 2018

Posttraumatic enophthalmos due to isolated or complex orbital fractures can contribute to diplopia. Current evidence recommends early repair. However, little is known about the outcome of enophthalmos correction when repair occurs beyond 30 days after trauma. In this systematic review, the authors aim to evaluate the current evidence on functional outcomes after delayed repair of posttraumatic enophthalmos.

Two independent assessors undertook a systematic review of the literature using multiple databases. The authors’ inclusion criteria identified studies involving patients at least 14 years of age who had surgical correction of persistent enophthalmos 30 days after initial trauma. Each eligible paper was included after critical appraisal using validated guidelines. Data on preoperative and postoperative enophthalmos and diplopia in each study was extracted. The pattern of fracture was also noted.

The authors’ search for the medical databases yielded 1053 articles, of which 6 eligible papers were included. Meta-analysis was performed. In patients with complex injuries involving orbital and mid-facial fractures, diplopia resolution was calculated to be 53%, and enophthalmos was corrected in 83% of the patients. In patients with isolated orbital fractures, 53% had resolution of their diplopia, and enophthalmos was corrected in 88% of the patients.

Enophthalmos can be corrected to within 2 mm of the contralateral eye in both the isolated and complex orbital fractures in patients who present 30 days or greater after injury. Based on the studies reviewed, there is less predictability in diplopia resolution.
Lacrimal Apparatus Procurement in Face Transplantation
Authors: Hasan Asif , Maciver Colin , Toure Gaoussou , Meningaud Jean-Paul
Published: March 2018

The aesthetic outcome of a well-planned and executed vascularized composite tissue face allotransplant is unquestionable; however, complete functional restoration is necessary. The authors studied the possibility of restoring tear duct function in face transplant recipients. They also examined the technical specifics and feasibility of incorporating a lacrimal drainage apparatus into facial allografting. The authors performed a standardized face vascularized composite allograft on 4 hemi-faces (2 fresh cadavers). On one side of the face, a soft tissue myocutaneous alloflap was raised. They attempted to incorporate the nasolacrimal apparatus into the allograft to develop and describe an efficient harvest method. On the contralateral side, an osteocutaneous alloflap was raised with the midface and mandible. The authors describe 2 techniques to incorporate the lacrimal drainage system. The authors retrieved the graft in a consistent and replicable fashion within conventional alloflap retrieval times. The authors successfully incorporated the entire nasolacrimal drainage system into the conventional soft tissue-only myocutaneous alloflap by transforming it into a modified mini-osteomyocutaneous alloflap. They demonstrated that the contralateral conventional bi-maxillary osteocutaneous alloflap procedure, as an alternative comparative technique, provided another means to restore lacrimal drainage. In conclusion, surgically harvesting the nasolacrimal apparatus is technically feasible in vascularized composite tissue allotransplantation. Before translating this to a clinical setting, further dissections are necessary to explore the technical specifics of how to insert the harvested nasolacrimal apparatus into the recipient to restore a conduit for tear drainage. This study is the first step towards a fully functioning lacrimal drainage system in face transplant recipients.
Surgical Management of Mandibular Angle Fractures
Authors: An Wei , Ainiwaer Aisaiti , Wusiman Patiguli , Ali Gulibusitan , Moming Adili
Published: March 2018

Purpose:

The study proposed to determine the superiority between different fixation methods in the mandibular angle fractures (MAFs) and to evaluate best option for surgeon and patient.

Methods:

A systematic review was conducted according to PRISMA guidelines, examining Medline-Ovid, Embase, and Pubmed databases. The quality of studies was assessed, and the odds risk (OR) with its corresponding 95% confidence interval (CI) was assessed to measure the effect size. Subgroup analyses by different fracture regions and different miniplate sizes were performed. Publication bias was measured by a funnel plot.

Results:

Twenty-one articles were enrolled in this review: 8 randomized controlled trials , 2 controlled clinical trials, and 11 retrospective studies. There were significant advantages for 3-dimensional (3D) miniplate (OR = 0.48,P = 0.003, 95% CI, 0.35–0.67) and 1 miniplate (OR 0.38, 95% CI 0.25–0.58,P < 0.00001). The cumulative OR for locking miniplate was 0.45, showing that the utilizing of locking mini-plate in management of MAFs decreases postoperative complications risk by 55% over the use of nonlocking mini-plate.

Conclusions:

The results of this review indicated that the use of 3D miniplate, locking plate, and 1 plate were more advanced to 2 miniplates technique in low incidence of postoperative complications in the treatment of MAFs.
A Novel Implementation of Magnetic Levitation to Quantify Leukocyte Size, Morphology, and Magnetic Properties to Identify Patients With Sepsis
Authors: Andersen Mikkel S. , Lu Shulin , Lopez Gregory J. , Lassen Annmarie T. , Shapiro Nathan I. , Ghiran Ionita C.
Published: March 2018

Background:

We have developed a novel, easily implementable methodology using magnetic levitation to quantify circulating leukocyte size, morphology, and magnetic properties, which may help in rapid, bedside screening for sepsis.

Objective:

Our objectives were to describe our methodological approach to leukocyte assessment, and to perform a pilot investigation to test the ability of magnetic levitation to identify and quantify changes in leukocyte size, shape, density, and/or paramagnetic properties in healthy controls and septic patients.

Methods:

This prospective, observational cohort study was performed in a 56,000/y visit emergency department (ED) and affiliated outpatient phlebotomy laboratory. Inclusion criteria were admittance to the hospital with suspected or confirmed infection for the septic group, and we enrolled the controls from ED/outpatient patients without infection or acute illness. The bench-top experiments were performed using magnetic levitation to visualize the leukocytes. We primary sought to compare septic patients with noninfected controls and secondary to assess the association with sepsis severity. Our covariates were area, length, width, roundness, and standard deviation (SD) of levitation height. We used unpairedttest and area under the curve (AUC) for the assessment of accuracy in distinguishing between septic and control patients.

Results:

We enrolled 39 noninfected controls and 22 septic patients. Our analyses of septic patients compared with controls showed: mean cell area in pixels (px) 562 ± 111 vs. 410 ± 45,P < 0.0001, AUC = 0.89 (0.80–0.98); length (px), 29 ± 2.5 vs. 25 ± 1.9,P < 0.0001, AUC = 0.90 (0.83–0.98); and width (px), 27 ± 2.4 vs. 23 ± 1.5,P < 0.0001, AUC = 0.92 (0.84–0.99). Cell roundness: 2.1 ± 1.0 vs. 2.2 ± 1.2,P = 0.8, AUC = 0.51. SD of the levitation height (px) was 72 ± 25 vs. 47 ± 16,P < 0.001, AUC = 0.80 (0.67–0.93).

Conclusions:

Septic patients had circulating leukocytes with especially increased size parameters, which distinguished sepsis from noninfected patients with promising high accuracy. This portal-device compatible technology shows promise as a potential bedside diagnostic.
Identifying Barriers to Preemptive Kidney Transplantation in a Living Donor Transplant Cohort
Authors: Helmick Ryan A. , Jay Colleen L. , Price Brittany A. , Dean Patrick G. , Stegall Mark D.
Published: March 2018

Background

Despite substantial evidence demonstrating clear benefit, rates of preemptive kidney transplantation (PreKTx) remain low in the United States. Our goal was to identify barriers to PreKTx.

Methods

Using a telephone-administered questionnaire including questions about barriers, timing of referral, timing of education, we retrospectively studied first living donor kidney transplant recipients (2006-2010) at Mayo Clinic, Rochester, MN. Of 235 patients, 145 (62%) responded to the questionnaire (74 PreKTx and 71 non-PreKTx). We compared categorical data with Fisher exact test and median times with Wilcoxon rank sum test.

Results

Polycystic kidney disease (PCKD), longer median time between diagnosis and transplant, and time between education about transplant and transplant correlated with PreKTx (P < 0.01). The presence of at least 1 patient-identified barrier (lack of referral, financial barriers, medical barriers, no identified living donor and donor evaluation delays) was associated with non-PreKTx (0.034) though no single barrier predominated. Age, education level, insurance status and source of referral (primary care, nephrology, and nonphysician referral) were not associated with the rate of PreKTx. Univariate logistic regression identified white race, PCKD, and increased time from diagnosis as factors favoring PreKTx; PCKD and increased time remained significant factors after multivariate analysis.

Conclusions

Even among a patient population that is primarily white, educated, and has a spouse or first-degree relative donor, PreKTx rates remain concerningly low. Increased time between diagnosis or education and transplant are predictors of PreKTx. Greater emphasis on transplant education earlier in the stages of chronic kidney disease and community outreach from transplant centers may help to increase the rate of PreKTx.
Baseline Amnestic Severity Predicts Progression From Amnestic Mild Cognitive Impairment to Alzheimer Disease Dementia at 3 Years
Authors: Bradfield Nicholas I. , Ellis Kathryn A. , Savage Greg , Maruff Paul , Burnham Samantha , Darby David , Lautenschlager Nicola T. , Martins Ralph N. , Masters Colin L. , Rainey-Smith Stephanie R. , Robertson Joanne , Rowe Christopher , Woodward Michael , Ames David
Published: March 2018

Background:

Given the long preclinical disease course of Alzheimer disease (AD) pathology, novel treatments may be more efficacious if administered before the emergence of dementia. Thus, accurate prediction of who will develop AD dementia is of key importance in selecting individuals for trials of treatment and may become crucial for future selection of patients for therapy.

Methods:

As part of the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Ageing, 901 individuals who did not have dementia were recruited. We assigned individuals according to Petersen criteria and Winblad criteria for Mild Cognitive Impairment (MCI) at baseline. We then stratified individuals with amnestic MCI into 2 groups according to the severity of their memory impairment on baseline neuropsychological assessment. Incident diagnosis of AD dementia was established by consensus of an expert panel at 36 months.

Results:

At 36 months, 725 (80.5%) participants were followed up, 54 (7.4%) of whom developed AD dementia. Subjects with amnestic MCI according to Petersen criteria were more likely to develop AD dementia [positive predictive value; PPV, 24.1%; 95% confidence interval (CI), 18.4-30.6] than healthy controls (PPV, 1.0%; 95% CI, 0.3-2.3). Winblad criteria were also effective, with multiple domain amnestic MCI being most accurate at predicting AD dementia (PPV, 47.3%; 95% CI, 33.7-61.2). Finally, more severe amnestic impairment below the median was useful for predicting the development of AD dementia in single domain amnestic MCI (PPV, 28.1%; 95% CI, 17.0-41.5) and in multiple domain amnestic MCI (PPV, 65.7%; 95% CI, 47.8-80.9).

Conclusions:

Memory impairment per se, impairment in multiple cognitive domains and severity of memory impairment were all associated with greater risk of developing AD dementia in this sample. Characterizing the severity of memory impairment may provide prognostic stratification within Petersen or Winblad taxonomies of amnestic MCI.
Cationic antimicrobial peptides do not change recombination frequency in
Escherichia coli
Authors: Rodríguez-Rojas Alexandro , Moreno-Morales Javier , Mason A. James , Rolff Jens
Published: March 2018

Cationic antimicrobial peptides are ubiquitous immune effectors of multicellular organisms. We previously reported, that in contrast to most of the classic antibiotics, cationic antimicrobial peptides (AMPs) do not increase mutation rates in
E. coli
. Here, we provide new evidence showing that AMPs do not stimulate or enhance bacterial DNA recombination in the surviving fractions. Recombination accelerates evolution of antibiotic resistance. Our findings have implications for our understanding of host–microbe interactions, the evolution of innate immune defences, and shed new light on the dynamic of antimicrobial-resistance evolution.
Sperm competition as an under-appreciated factor in domestication
Authors: Hulme-Beaman Ardern , Searle Jeremy B. , Stockley Paula
Published: March 2018

Humans created an environment that increased selective pressures on subgroups of those species that became domestic. We propose that the domestication process may in some cases have been facilitated by changes in mating behaviour and resultant sperm competition. By adapting to sperm competition, proto-domestic animals could potentially have outcompeted their wild counterparts in human-constructed niches. This could have contributed to the restriction of gene flow between the proto-domesticates and their wild counterparts, thereby promoting the fixation of other domestication characteristics. Further to this novel perspective for domestication, we emphasize the general potential of postcopulatory sexual selection in the restriction of gene flow between populations, and urge more studies.
Urban blackbirds have shorter telomeres
Authors: Ibáñez-Álamo Juan Diego , Pineda-Pampliega Javier , Thomson Robert L. , Aguirre José I. , Díez-Fernández Alazne , Faivre Bruno , Figuerola Jordi , Verhulst Simon
Published: March 2018

Urbanization, one of the most extreme human-induced environmental changes, represents a major challenge for many organisms. Anthropogenic habitats can have opposing effects on different fitness components, for example, by decreasing starvation risk but also health status. Assessment of the net fitness effect of anthropogenic habitats is therefore difficult. Telomere length is associated with phenotypic quality and mortality rate in many species, and the rate of telomere shortening is considered an integrative measure of the ‘life stress’ experienced by an individual. This makes telomere length a promising candidate for examining the effects of urbanization on the health status of individuals. We investigated whether telomere length differed between urban and forest-dwelling common blackbirds (
Turdus merula
). Using the terminal restriction fragment assay, we analysed telomere length in yearlings and older adults from five population dyads (urban versus forest) across Europe. In both age classes, urban blackbirds had significantly shorter telomeres (547 bp) than blackbirds in natural habitats, indicating lower health status in urban blackbirds. We propose several potential hypotheses to explain our results. Our findings show that even successful city dwellers such as blackbirds pay a price for living in these anthropogenic habitats.
Local interactions and self-organized spatial patterns stabilize microbial cross-feeding against cheaters
Authors: Stump Simon Maccracken , Johnson Evan Curtis , Klausmeier Christopher A.
Published: March 2018

Mutualisms are ubiquitous, but models predict they should be susceptible to cheating. Resolving this paradox has become relevant to synthetic ecology: cooperative cross-feeding, a nutrient-exchange mutualism, has been proposed to stabilize microbial consortia. Previous attempts to understand how cross-feeders remain robust to non-producing cheaters have relied on complex behaviour (e.g. cheater punishment) or group selection. Using a stochastic spatial model, we demonstrate two novel mechanisms that can allow cross-feeders to outcompete cheaters, rather than just escape from them. Both mechanisms work through the spatial segregation of the resources, which prevents individual cheaters from acquiring the resources they need to reproduce. First, if microbe dispersal is low but resources are shared widely, then the cross-feeders self-organize into stable spatial patterns. Here the cross-feeders can build up where the resource they need is abundant, and send their resource to where their partner is, separating resources at regular intervals in space. Second, if dispersal is high but resource sharing is local, then random variation in population density creates small-scale variation in resource density, separating the resources from each other by chance. These results suggest that cross-feeding may be more robust than previously expected and offer strategies to engineer stable consortia.
From flagellar undulations to collective motion: predicting the dynamics of sperm suspensions
Authors: Schoeller Simon F. , Keaveny Eric E.
Published: March 2018

Swimming cells and microorganisms are as diverse in their collective dynamics as they are in their individual shapes and propulsion mechanisms. Even for sperm cells, which have a stereotyped shape consisting of a cell body connected to a flexible flagellum, a wide range of collective dynamics is observed spanning from the formation of tightly packed groups to the display of larger-scale, turbulence-like motion. Using a detailed mathematical model that resolves flagellum dynamics, we perform simulations of sperm suspensions containing up to 1000 cells and explore the connection between individual and collective dynamics. We find that depending on the level of variation in individual dynamics from one swimmer to another, the sperm exhibit either a strong tendency to aggregate, or the suspension exhibits large-scale swirling. Hydrodynamic interactions govern the formation and evolution of both states. In addition, a quantitative analysis of the states reveals that the flows generated at the time scale of flagellum undulations contribute significantly to the overall energy in the surrounding fluid, highlighting the importance of resolving these flows.
Bayesian model evidence as a practical alternative to deviance information criterion
Authors: Pooley C. M. , Marion G.
Published: March 2018

While model evidence is considered by Bayesian statisticians as a gold standard for model selection (the ratio in model evidence between two models giving the Bayes factor), its calculation is often viewed as too computationally demanding for many applications. By contrast, the widely used deviance information criterion (DIC), a different measure that balances model accuracy against complexity, is commonly considered a much faster alternative. However, recent advances in computational tools for efficient multi-temperature Markov chain Monte Carlo algorithms, such as steppingstone sampling (SS) and thermodynamic integration schemes, enable efficient calculation of the Bayesian model evidence. This paper compares both the capability (i.e. ability to select the true model) and speed (i.e. CPU time to achieve a given accuracy) of DIC with model evidence calculated using SS. Three important model classes are considered: linear regression models, mixed models and compartmental models widely used in epidemiology. While DIC was found to correctly identify the true model when applied to linear regression models, it led to incorrect model choice in the other two cases. On the other hand, model evidence led to correct model choice in all cases considered. Importantly, and perhaps surprisingly, DIC and model evidence were found to run at similar computational speeds, a result reinforced by analytically derived expressions.
pH-responsive polymeric micelles self-assembled from amphiphilic copolymer modified with lipid used as doxorubicin delivery carriers
Authors: Zhou Xin Xin , Jin Long , Qi Rui Qun , Ma Teng
Published: March 2018

In the present study, a novel pH-responsive amphiphilic copolymer, 1,2-distearoyl-
sn
-glycero-3-phosphoethanolamine-
N
-[methoxy(polyethylene glycol)] conjugated poly(β-amino esters) (DSPE-
b
-PEG-
b
-PAE-
b
-PEG-
b
-DSPE), was designed and successfully synthesized via Michael-type step polymerization. The chemical structure of the pentablock copolymer was confirmed with proton nuclear magnetic resonance (
1
H-NMR) and Fourier transform infrared (FT-IR) spectroscopy. The copolymer was able to self-assemble into core/shell polymeric micelles in aqueous solution at low concentrations, and its critical micelle concentration (CMC) value was 4.5 mg l
−1
determined by fluorescence spectrophotometry. The p
K
b
value of the copolymer was about 6.5, confirmed by acid–base titration, indicating the pH-sensitivity of the polymeric micelle. The hydrodynamic diameter, distribution and zeta potential of the polymeric micelles at different pH conditions were monitored by dynamic light scattering (DLS). Doxorubicin (DOX) was encapsulated into the core of the micelles with a high drug loading content (15.9%) and entrapment efficacy (60.4%).
In vitro
experiments demonstrated that the release behaviour of DOX from the DOX-loaded polymeric micelles (DOX-PMs) was pH-triggered. When the pH decreased from 7.4 to 5.0, the drug release rate was markedly accelerated. MTT assay showed that the copolymer had negligible cytotoxicity whereas the DOX-PMs displayed high toxicity for tumour cells such as B16F10, HepG2 and HeLa cell lines. The results demonstrated that these pH-sensitive polymeric micelles could be used as potential anti-cancer drug carriers for cancer chemotherapy with controlled release.
Analysis of wild macaque stone tools used to crack oil palm nuts
Authors: Proffitt T. , Luncz V. L. , Malaivijitnond S. , Gumert M. , Svensson M. S. , Haslam M.
Published: March 2018

The discovery of oil palm (Elaeis guineensis) nut-cracking by wild long-tailed macaques (Macaca fascicularis) is significant for the study of non-human primate and hominin percussive behaviour. Up until now, only West African chimpanzees (Pan troglodytes verus) and modern human populations were known to use stone hammers to crack open this particular hard-shelled palm nut. The addition of non-habituated, wild macaques increases our comparative dataset of primate lithic percussive behaviour focused on this one plant species. Here, we present an initial description of hammerstones used by macaques to crack oil palm nuts, recovered from active nut-cracking locations on Yao Noi Island, Ao Phang Nga National Park, Thailand. We combine a techno-typological approach with microscopic and macroscopic use-wear analysis of percussive damage to characterize the percussive signature of macaque palm oil nut-cracking tools. These artefacts are characterized by a high degree of battering and crushing on most surfaces, which is visible at both macro and microscopic levels. The degree and extent of this damage is a consequence of a dynamic interplay between a number of factors, including anvil morphology and macaque percussive techniques. Beyond the behavioural importance of these artefacts, macaque nut-cracking represents a new target for primate archaeological investigations, and opens new opportunities for comparisons between tool using primate species and with early hominin percussive behaviour, for which nut-cracking has been frequently inferred.
Resurrected ‘ancient’
Daphnia
genotypes show reduced thermal stress tolerance compared to modern descendants
Authors: Yousey Aime'e M. , Chowdhury Priyanka Roy , Biddinger Nicole , Shaw Jennifer H. , Jeyasingh Punidan D. , Weider Lawrence J.
Published: March 2018

Understanding how populations adapt to rising temperatures has been a challenge in ecology. Research often evaluates multiple populations to test whether local adaptation to temperature regimes is occurring. Space-for-time substitutions are common, as temporal constraints limit our ability to observe evolutionary responses. We employed a resurrection ecology approach to understand how thermal tolerance has changed in a
Daphnia pulicaria
population over time. Temperatures experienced by the oldest genotypes were considerably lower than the youngest. We hypothesized clones were adapted to the thermal regimes of their respective time periods. We performed two thermal shock experiments that varied in length of heat exposure. Overall trends revealed that younger genotypes exhibited higher thermal tolerance than older genotypes; heat shock protein (hsp70) expression increased with temperature and varied among genotypes, but not across time periods. Our results indicate temperature may have been a selective factor on this population, although the observed responses may be a function of multifarious selection. Prior work found striking changes in population genetic structure, and in other traits that were strongly correlated with anthropogenic changes. Resurrection ecology approaches should help our understanding of interactive effects of anthropogenic alterations to temperature and other stressors on the evolutionary fate of natural populations.
A biogeographic perspective on the evolution of fire syndromes in pine trees (
Pinus
: Pinaceae)
Authors: Badik Kevin J. , Jahner Joshua P. , Wilson Joseph S.
Published: March 2018

Our goals were to explore the relationship between biogeography and the evolution of fire-adaptive syndromes in the genus
Pinus
. We used a previously published time-calibrated phylogeny and conducted ancestral trait reconstruction to estimate the likely timing of diversification in
Pinus
, and to determine when fire-adaptive syndromes evolved in the lineage. To explore trait conservation among fire syndromes and to investigate historical biogeography, we constructed ancestral state reconstructions using the program RASP and estimated the degree of conservatism for fire-adapted traits in the program BaTS. Our reconstructions suggest that the Bering land bridge, which connected North America and Asia, probably played a major role in early pine evolution. Our estimates indicated that fire-adaptive syndromes seem to have evolved more frequently in New World taxa and probably are related to the uplift of major North American mountain ranges. Our data suggest that certain geographically widespread adaptations to fire evolved repeatedly, possibly due to localized changes in climate and environment, rather than resulting from large dispersal events of pre-adapted individuals.
Rayleigh wave at the surface of a general anisotropic poroelastic medium: derivation of real secular equation
Authors: Sharma M. D.
Published: March 2018

A secular equation governs the propagation of Rayleigh wave at the surface of an anisotropic poroelastic medium. In the case of anisotropy with symmetry, this equation is obtained as a real irrational equation. But, in the absence of anisotropic symmetries, this secular equation is obtained as a complex irrational equation. True surface waves in non-dissipative materials decay only with depth. That means, propagation of Rayleigh wave in anisotropic poroelastic solid should be represented by a real phase velocity. In this study, the determinantal system leading to the complex secular equation is manipulated to obtain a transformed equation. Even for arbitrary (triclinic) anisotropy, this transformed equation remains real for the propagation of true surface waves. Such a real secular equation is obtained with the option of boundary pores being opened or sealed. A numerical example is solved to study the existence and propagation of Rayleigh waves in porous media for the top three (i.e. triclinic, monoclinic and orthorhombic) anisotropies.
Genetic diversity, inbreeding and cancer
Authors: Ujvari Beata , Klaassen Marcel , Raven Nynke , Russell Tracey , Vittecoq Marion , Hamede Rodrigo , Thomas Frédéric , Madsen Thomas
Published: March 2018

Genetic diversity is essential for adaptive capacities, providing organisms with the potential of successfully responding to intrinsic and extrinsic challenges. Although a clear reciprocal link between genetic diversity and resistance to parasites and pathogens has been established across taxa, the impact of loss of genetic diversity by inbreeding on the emergence and progression of non-communicable diseases, such as cancer, has been overlooked. Here we provide an overview of such associations and show that low genetic diversity and inbreeding associate with an increased risk of cancer in both humans and animals. Cancer being a multifaceted disease, loss of genetic diversity can directly (via accumulation of oncogenic homozygous mutations) and indirectly (via increased susceptibility to oncogenic pathogens) impact abnormal cell emergence and escape of immune surveillance. The observed link between reduced genetic diversity and cancer in wildlife may further imperil the long-term survival of numerous endangered species, highlighting the need to consider the impact of cancer in conservation biology. Finally, the somewhat incongruent data originating from human studies suggest that the association between genetic diversity and cancer development is multifactorial and may be tumour specific. Further studies are therefore crucial in order to elucidate the underpinnings of the interactions between genetic diversity, inbreeding and cancer.
Male spiders control offspring sex ratio through greater production of female-determining sperm
Authors: Vanthournout Bram , Busck Mette Marie , Bechsgaard Jesper , Hendrickx Frederik , Schramm Andreas , Bilde Trine
Published: March 2018

Sex allocation theory predicts that when sons and daughters have different reproductive values, parents should adjust offspring sex ratio towards the sex with the higher fitness return. Haplo-diploid species directly control offspring sex ratio, but species with chromosomal sex determination (CSD) were presumed to be constrained by Mendelian segregation. There is now increasing evidence that CSD species can adjust sex ratio strategically, but the underlying mechanism is not well understood. One hypothesis states that adaptive control is more likely to evolve in the heterogametic sex through a bias in gamete production. We investigated this hypothesis in males as the heterogametic sex in two social spider species that consistently show adaptive female-biased sex ratio and in one subsocial species that is characterized by equal sex ratio. We quantified the production of male (0) and female (X) determining sperm cells using flow cytometry, and show that males of social species produce significantly more X-carrying sperm than 0-sperm, on average 70%. This is consistent with the production of more daughters. Males of the subsocial species produced a significantly lower bias of 54% X-carrying sperm. We also investigated whether inter-genomic conflict between hosts and their endosymbionts may explain female bias. Next generation sequencing showed that five common genera of bacterial endosymbionts known to affect sex ratio are largely absent, ruling out that endosymbiont bacteria bias sex ratio in social spiders. Our study provides evidence for paternal control over sex allocation through biased gamete production as a mechanism by which the heterogametic sex in CSD species adaptively adjust offspring sex ratio.
Nuisance Effects and the Limitations of Nuisance Regression in Dynamic Functional Connectivity fMRI
Authors: Nalci Alican , Rao Bhaskar D. , Liu Thomas T.
Published: March 2018

In resting-state fMRI, dynamic functional connectivity (DFC) measures are used to characterize temporal changes in the brain’s intrinsic functional connectivity. A widely used approach for DFC estimation is the computation of the sliding window correlation between blood oxygenation level dependent (BOLD) signals from different brain regions. Although the source of temporal fluctuations in DFC estimates remains largely unknown, there is growing evidence that they may reflect dynamic shifts between functional brain networks. At the same time, recent findings suggest that DFC estimates might be prone to the influence of nuisance factors such as the physiological modulation of the BOLD signal. Therefore, nuisance regression is used in many DFC studies to regress out the effects of nuisance terms prior to the computation of DFC estimates. In this work we examined the relationship between DFC estimates and nuisance factors. We found that DFC estimates were significantly correlated with temporal fluctuations in the magnitude (norm) of various nuisance regressors, with significant correlations observed in the majority (76%) of the cases examined. Significant correlations between the DFC estimates and nuisance regressor norms were found even when the underlying correlations between the nuisance and fMRI time courses were relatively small. We then show that nuisance regression does not eliminate the relationship between DFC estimates and nuisance norms, with significant correlations observed in the majority (71%) of the cases examined after nuisance regression. We present theoretical bounds on the difference between DFC estimates obtained before and after nuisance regression and relate these bounds to limitations in the efficacy of nuisance regression with regards to DFC estimates.