bluuebunny/crossref_metadata_2025 huggingface dataset:
Scaling the extinction vortex: Body size as a predictor of population dynamics close to extinction events
Authors: Williams Nathan F. , McRae Louise , Freeman Robin , Capdevila Pol , Clements Christopher F.
Published: May 2021

Mutual reinforcement between abiotic and biotic factors can drive small populations into a catastrophic downward spiral to extinction—a process known as the “extinction vortex.” However, empirical studies investigating extinction dynamics in relation to species' traits have been lacking.

We assembled a database of 35 vertebrate populations monitored to extirpation over a period of at least ten years, represented by 32 different species, including 25 birds, five mammals, and two reptiles. We supplemented these population time series with species‐specific mean adult body size to investigate whether this key intrinsic trait affects the dynamics of populations declining toward extinction.

We performed three analyses to quantify the effects of adult body size on three characteristics of population dynamics: time to extinction, population growth rate, and residual variability in population growth rate.

Our results provide support for the existence of extinction vortex dynamics in extirpated populations. We show that populations typically decline nonlinearly to extinction, while both the rate of population decline and variability in population growth rate increase as extinction is approached. Our results also suggest that smaller‐bodied species are particularly prone to the extinction vortex, with larger increases in rates of population decline and population growth rate variability when compared to larger‐bodied species.

Our results reaffirm and extend our understanding of extinction dynamics in real‐life extirpated populations. In particular, we suggest that smaller‐bodied species may be at greater risk of rapid collapse to extinction than larger‐bodied species, and thus, management of smaller‐bodied species should focus on maintaining higher population abundances as a priority.
Does stress mess with rodents’ heads? Influence of habitat amount and genetic factors in mandible fluctuating asymmetry in South American water rats (Nectomys squamipes, Sigmodontinae) from Brazilian Atlantic rainforest remnants
Authors: Caccavo Aldo , Lemos Hudson , Maroja Luana S. , Gonçalves Pablo Rodrigues
Published: May 2021

Loss of developmental stability can lead to deviations from bilateral symmetry (i.e. Fluctuating Asymmetry ‐ FA), and is thought to be caused by environmental and genetic factors associated with habitat loss and stress. Therefore, levels of FA might be a valuable tool to monitor wild populations if FA serves as an indicator of exposure to stress due to impacts of habitat loss and fragmentation. In studies examining FA and habitat fragmentation, FA levels are often explained by loss of genetic variation, though few studies have addressed FA’s use as indicator of environmental impact. Here, we investigated whether habitat loss, genetic variation, and/or inbreeding affect the developmental instability in Brazilian Atlantic forest populations of a Neotropical water rat (Nectomys squamipes). We sampled individuals from eight sites within Atlantic forest remnants with different amounts of available forest habitat and assessed FA levels with geometric morphometric techniques using adult mandibles. We used observed heterozygosity (Ho) and inbreeding coefficient (Fis), from seven microsatellite markers, as a proxy of genetic variation at individual and population levels. Populations were not significantly different for shape or size FA levels. Furthermore, interindividual variation in both shape and size FA levels and interpopulational differences in size FA levels were best explained by chance. However, habitat amount was negatively associated with both interpopulational variance and average shape FA levels. This association was stronger in populations living in areas with <28% of forest cover, which presented higher variance and higher average FA, suggesting thatNectomys squamipesmight have a tolerance threshold to small availability of habitat. Our work is one of the first to use FA to address environmental stress caused by habitat loss in small mammal populations from a Neotropical biome. We suggest that shape FA might serve as a conservation tool to monitor human impact on natural animal populations.
Spatial–temporal variations in deforestation hotspots in Sumatra and Kalimantan from 2001–2018
Authors: Singh Minerva , Yan Siheng
Published: May 2021

Tropical deforestation varies temporally and spatially which can inhibit the ability of existing protected areas to stem forest loss. Identifying the spatial–temporal distribution of deforestation and its concentration can help decision makers decide conservation priorities and leverage limited resources. This study assessed how topographic and anthropogenic variables affect deforestation patterns within and outside protected areas on the islands of Sumatra and Kalimantan in Indonesia. Emerging hotspot analysis (EHA) was used to evaluate spatial and temporal trends of forest loss on the Hansen annual forest loss data for these islands from 2001–2018. For the two islands, most hotspots were detected outside protected areas; those within protected areas were mainly concentrated at boundaries, where lower elevation/slope and high human pressure could be observed. New hotspots were identified within the three PAs in Sumatra, while three kinds of hotspots (consecutive, oscillating, and sporadic) were found in the two PAs of Kalimantan (Kutai and Teluk Kelumpang). Areas with high human pressure (average human footprint higher than 12) were covered by a high density of hotspots. The results identify specific areas where forest loss has emerged recently, which could indicate a conservation priority. It is suggested that new protected areas be established in locations showing intensifying and persistent hotspots—those where deforestation has occurred for ≥16 of 18 years of the study period.
The interaction of resource use and gene flow on the phenotypic divergence of benthic and pelagic morphs of Icelandic Arctic charr (Salvelinus alpinus)
Authors: Brachmann Matthew K. , Parsons Kevin , Skúlason Skúli , Ferguson Moira M.
Published: May 2021

Conceptual models of adaptive divergence and ecological speciation in sympatry predict differential resource use, phenotype–environment correlations, and reduced gene flow among diverging phenotypes. While these predictions have been assessed in past studies, connections among them have rarely been assessed collectively. We examined relationships among phenotypic, ecological, and genetic variation in Arctic charr (Salvelinus alpinus) from six Icelandic localities that have undergone varying degrees of divergence into sympatric benthic and pelagic morphs. We characterized morphological variation with geometric morphometrics, tested for differential resource use between morphs using stable isotopes, and inferred the amount of gene flow from single nucleotide polymorphisms. Analysis of stable isotopic signatures indicated that sympatric morphs showed similar difference in resource use across populations, likely arising from the common utilization of niche space within each population. Carbon isotopic signature was also a significant predictor of individual variation in body shape and size, suggesting that variation in benthic and pelagic resource use is associated with phenotypic variation. The estimated percentage of hybrids between sympatric morphs varied across populations (from 0% to 15.6%) but the majority of fish had genotypes (ancestry coefficients) characteristic of pure morphs. Despite evidence of reduced gene flow between sympatric morphs, we did not detect the expected negative relationship between divergence in resource use and gene flow. Three lakes showed the expected pattern, but morphs in the fourth showed no detectable hybridization and had relatively low differences in resource use between them. This coupled with the finding that resource use and genetic differentiation had differential effects on body shape variation across populations suggests that reproductive isolation maintains phenotypic divergence between benthic and pelagic morphs when the effects of resource use are relatively low. Our ability to assess relationships between phenotype, ecology, and genetics deepens our understanding of the processes underlying adaptive divergence in sympatry.
Behavioral repertoire of high‐shore littorinid snails reveals novel adaptations to an extreme environment
Authors: Ng Terence P. T. , Lau Sarah L. Y. , Davies Mark S. , Stafford Richard , Seuront Laurent , Hutchinson Neil , Hui Tommy T. Y. , Williams Gray A.
Published: May 2021

Species that inhabit high‐shore environments on rocky shores survive prolonged periods of emersion and thermal stress. Using two Hong Kong high‐shore littorinids (Echinolittorina malaccanaandE.radiata) as models, we examined their behavioral repertoire to survive these variable and extreme conditions. Environmental temperatures ranged from 4°C in the cool season to 55.5°C in the hot season, with strong seasonal and daily fluctuations. In the hot season, both species allocated >35% of their activity budgets to stress‐mitigating thermoregulatory behaviors (e.g. standing, towering) and relatively small proportions to foraging (<20%) and reproduction (<10%). In the assumedly benign cool season, greater proportions (>70%) of activity budgets were allocated to stress mitigation behaviors (crevice occupation, aggregation formation). Both species exhibited multifunctional behaviors that optimized time use during their tidally‐constrained activity window in the hot season. Females mated while foraging when awash by the rising tide, and some males crawled on top of females prior to ceasing movement to form 'towers', which have both thermoregulatory benefits and reduce searching time for mates during subsequent activity. The function of such behaviors varies in a state‐dependent manner, for example, the function of trail following changes over an activity cycle from mate searching on rising tides, to stress mitigation on falling tides (aiding aggregation formation), and to both functions through tower formation just before movement stops. Many of these behavioral responses are, therefore, multifunctional and can vary according to local conditions, allowing snails in this family to successfully colonize the extreme high‐shore environment.
Molecular diet analysis of neotropical bats based on fecal DNA metabarcoding
Authors: Ingala Melissa R. , Simmons Nancy B. , Wultsch Claudia , Krampis Konstantinos , Provost Kaiya L. , Perkins Susan L.
Published: May 2021

Bat communities in the Neotropics are some of the most speciose assemblages of mammals on Earth, with regions supporting more than 100 sympatric species with diverse feeding ecologies. Because bats are small, nocturnal, and volant, it is difficult to directly observe their feeding habits, which has resulted in their classification into broadly defined dietary guilds (e.g., insectivores, carnivores, and frugivores). Apart from these broad guilds, we lack detailed dietary information for many species and therefore have only a limited understanding of interaction networks linking bats and their diet items. In this study, we used DNA metabarcoding of plants, arthropods, and vertebrates to investigate the diets of 25 bat species from the tropical dry forests of Lamanai, Belize. Our results report some of the first detection of diet items for the focal bat taxa, adding rich and novel natural history information to the field of bat ecology. This study represents a comprehensive first effort to apply DNA metabarcoding to bat diets at Lamanai and provides a useful methodological framework for future studies testing hypotheses about coexistence and niche differentiation in the context of modern high‐throughput molecular data.
Historical surveys reveal a long‐term decline in muskrat populations
Authors: Sadowski Carrie , Bowman Jeff
Published: May 2021

The muskrat (Ondatra zibethicus) is an iconic species in Canada, valued for both its fur and its integral role in wetland ecosystems, and widely regarded for its perseverance. However, the resilience of this semiaquatic mammal seems to be in question now as increasing evidence points to widespread population declines. Recent analyses of harvest data across North America suggest a reduction in their numbers, but this has not been widely corroborated by population surveys. In this study we replicated historic muskrat house count surveys at two large Great Lakes coastal wetlands and present confirmation that declines in muskrat harvest correspond to actual declines in muskrat abundance. At the Point Pelee National Park marsh and the Matchedash Bay‐Gray Marsh wetland we found that mean muskrat house counts declined by 93% and 91% respectively between historic surveys 40–50 yrs ago and contemporary surveys over the past 7 yrs. The factors responsible for these dramatic declines remain unclear but there may be a relationship with changes in the habitat quality of these wetlands that have occurred over the same time frame. Not only is the loss of muskrats an issue for the resulting loss of the wetland ecosystem services they provide, but it may be an indication of broader marsh ecosystem degradation. As such, a scarcity of muskrats should be considered a red flag for the state of biodiversity in our wetlands. Continued surveys and ongoing research are needed to shed more light on the current status of muskrat populations and their marsh habitats across their native range.
Historic range dynamics in Kaiser's mountain newt (Neurergus kaiseri): Insights from phylogeographic analyses and species distribution modeling
Authors: Vaissi Somaye
Published: May 2021

Vulnerable Kaiser's mountain newt, Neurergus kaiseri, is endemic to highland streams, springs, and pools of the southwestern Zagros mountain, Iran. The present study aimed to use an integration of phylogeographical and species distribution modeling (SDM) approaches to provide new insights into the evolutionary history of the species throughout Quaternary climate oscillations. The phylogeographical analysis was followed by analyzing two mitochondrial DNA (mt‐DNA) markers including 127 control region (D‐loop) and 72 NADH dehydrogenase 2 (ND2) sequences from 15 populations in the entire species range that were obtained from GenBank. Potential recent and past distribution (the Last Glacial Maximum, LGM, 21 Kya and the Mid‐Holocene, 6 Kya) reconstructed by ensemble SDM using nine algorithms with CCSM4, MIROC‐ESM, and MPI‐ESM‐P models. N. kaiseri displayed two distinct lineages in the northern and southern regions that diverged in the Early‐Pleistocene. The demographics analysis showed signs of a slight increase in effective population size for both northern and southern populations in the Mid‐Pleistocene. Biogeography analysis showed that both vicariance and dispersal events played an important role in the formation of recent species distribution of N. kaiseri. Based on SDM projection onto paleoclimatic data, N. kaiseri displayed a scenario of past range expansion that followed by postglacial contraction. The models showed that the distribution range of the species may have shifted to a lower altitude during LGM while with amelioration of climatic during Mid‐Holocene to recent conditions caused the species to shift to the higher altitude. The findings of the current study support the hypothesis that the Zagros mountains​ may be acting as climatic refugia and play an important role in the protection of isolated populations during climate oscillations.
Rewilding with invertebrates and microbes to restore ecosystems: Present trends and future directions
Authors: Contos Peter , Wood Jennifer L. , Murphy Nicholas P. , Gibb Heloise
Published: May 2021

Restoration ecology has historically focused on reconstructing communities of highly visible taxa while less visible taxa, such as invertebrates and microbes, are ignored. This is problematic as invertebrates and microbes make up the vast bulk of biodiversity and drive many key ecosystem processes, yet they are rarely actively reintroduced following restoration, potentially limiting ecosystem function and biodiversity in these areas.

In this review, we discuss the current (limited) incorporation of invertebrates and microbes in restoration and rewilding projects. We argue that these groups should be actively rewilded during restoration to improve biodiversity, ecosystem function outcomes, and highlight how they can be used to greater effect in the future. For example, invertebrates and microbes are easily manipulated, meaning whole communities can potentially be rewilded through habitat transplants in a practice that we refer to as “whole‐of‐community” rewilding.

We provide a framework for whole‐of‐community rewilding and describe empirical case studies as practical applications of this under‐researched restoration tool that land managers can use to improve restoration outcomes.

We hope this new perspective on whole‐of‐community restoration will promote applied research into restoration that incorporates all biota, irrespective of size, while also enabling a better understanding of fundamental ecological theory, such as colonization and competition trade‐offs. This may be a necessary consideration as invertebrates that are important in providing ecosystem services are declining globally; targeting invertebrate communities during restoration may be crucial in stemming this decline.
Honest signals and sexual conflict: Female lizards carry undesirable indicators of quality
Authors: Assis Braulio A. , Avery Julian D. , Tylan Catherine , Engler Heather I. , Earley Ryan L. , Langkilde Tracy
Published: May 2021

Sex differences in animal coloration often result from sex‐dependent regulatory mechanisms. Still, some species exhibit incomplete sexual dimorphism as females carry a rudimentary version of a costly male trait, leading to intralocus sexual conflict. The underlying physiology and condition dependence of these traits can inform why such conflicts remain unresolved. In eastern fence lizards (Sceloporus undulatus), blue iridophore badges are found in males and females, but melanin pigmentation underneath and surrounding badges is male‐exclusive. We track color saturation and area of badges across sexual maturity, and their relationship to individual quality (body condition and immunocompetence) and relevant hormones (testosterone and corticosterone). Saturation and testosterone were positively correlated in both sexes, but hormone and trait had little overlap between males and females. Saturation was correlated with body condition and immunocompetence in males but not in females. Co‐regulation by androgens may have released females from resource allocation costs of color saturation, even when in high condition. Badge area was independent of testosterone, but associated with low corticosterone in females, indicating that a nonsex hormone underlies incomplete sexual dimorphism. Given the evidence in this species for female reproductive costs associated with ornamentation, this sex‐nonspecific regulation of an honest signal may underlie intralocus sexual conflict.
Clinical phenogroups are more effective than left ventricular ejection fraction categories in stratifying heart failure outcomes
Authors: Gevaert Andreas B. , Tibebu Semra , Mamas Mamas A. , Ravindra Neal G. , Lee Shun Fu , Ahmad Tariq , Ko Dennis T. , Januzzi James L. , Van Spall Harriette G.C.
Published: May 2021

Aims

Heart failure (HF) guidelines place patients into 3 discrete groups according to left ventricular ejection fraction (LVEF): reduced (<40%), mid‐range (40–49%), and preserved LVEF (≥50%). We assessed whether clinical phenogroups offer better prognostication than LVEF.

Methods and results

This was a sub‐study of the Patient‐Centered Care Transitions in HF trial. We analysed baseline characteristics of hospitalized patients in whom LVEF was recorded. We used unsupervised machine learning to identify clinical phenogroups and, thereafter, determined associations between phenogroups and outcomes. Primary outcome was the composite of all‐cause death or rehospitalization at 6 and 12 months. Secondary outcome was the composite cardiovascular death or HF rehospitalization at 6 and 12 months. Cluster analysis of 1693 patients revealed six discrete phenogroups, each characterized by a predominant comorbidity: coronary heart disease, valvular heart disease, atrial fibrillation (AF), sleep apnoea, chronic obstructive pulmonary disease (COPD), or few comorbidities. Phenogroups were LVEF independent, with each phenogroup encompassing a wide range of LVEFs. For the primary composite outcome at 6 months, the hazard ratios (HRs) for phenogroups ranged from 1.25 [95% confidence interval (CI) 1.00–1.58 for AF] to 2.04 (95% CI 1.62–2.57 for COPD) (log‐rank P < 0.001); and at 12 months, the HRs for phenogroups ranged from 1.15 (95% CI 0.94–1.41 for AF) to 1.87 (95% 1.52–3.20 for COPD) (P < 0.002). LVEF‐based classifications did not separate patients into different risk categories for the primary outcomes at 6 months (P = 0.69) and 12 months (P = 0.30). Phenogroups also stratified risk of the secondary composite outcome at 6 and 12 months more effectively than LVEF.

Conclusion

Among patients hospitalized for HF, clinical phenotypes generated by unsupervised machine learning provided greater prognostic information for a composite of clinical endpoints at 6 and 12 months compared with LVEF‐based categories.

Trial Registration: ClinicalTrials.gov Identifier: NCT02112227
High density lipoprotein cholesterol / C reactive protein ratio in heart failure with preserved ejection fraction
Authors: Yano Masamichi , Nishino Masami , Ukita Kohei , Kawamura Akito , Nakamura Hitoshi , Matsuhiro Yutaka , Yasumoto Koji , Tsuda Masaki , Okamoto Naotaka , Tanaka Akihiro , Matsunaga‐Lee Yasuharu , Egami Yasuyuki , Shutta Ryu , Tanouchi Jun , Yamada Takahisa , Yasumura Yoshio , Tamaki Shunsuke , Hayashi Takaharu , Nakagawa Akito , Nakagawa Yusuke , Suna Shinichiro , Nakatani Daisaku , Hikoso Shungo , Sakata Yasushi ,   Osaka CardioVascular Conference (OCVC)‐Heart Failure Investigators
Published: May 2021

Aims

The impacts of high density lipoprotein cholesterol (HDL‐C) as an anti‐inflammatory and C reactive protein (CRP) as inflammatory properties on the pathogenesis of heart failure were reported. At present, the clinical significance of the HDL‐C/CRP ratio in heart failure with preserved ejection fraction (HFpEF) patients remains unknown.

Methods and results

We examined the data on 796 consecutive HFpEF (left ventricular ejection fraction ≥50%) patients hospitalized due to acute decompensated heart failure from the PURSUIT‐HFpEF registry, a prospective, multicentre observational study. We calculated the HDL/CRP ratios and evaluated the relationship between the values and clinical outcomes, including degree of cardiac function. The mean follow‐up duration was 420 ± 346 days. All‐cause death occurred in 118 patients, of which 51 were cardiac deaths. HDL/CRP ≤ 4.05 was independently and significantly associated with all‐cause death (odds ratio = 1.84, 95% CI: 1.06–3.20, P = 0.023), and HDL/CRP ≤ 3.14 was associated with cardiac death by multivariate Cox proportional hazard analysis (odds ratio = 2.86, 95% CI: 1.36–6.01, P = 0.003). HDL‐C/CRP ratio significantly correlated with the product of the left atrial volume and left ventricular mass index as well as the tricuspid annular plane systolic excursion by multiple regression analysis (standardized beta‐coefficient = −0.085, P = 0.034 and standardized beta‐coefficient = 0.081, P = 0.044, respectively).

Conclusions

HDL‐C/CRP ratio was a useful marker for predicting all‐cause death and cardiac death and correlated with left ventricular diastolic function and right ventricular systolic function in HFpEF patients.
Effects of echo‐optimization of left ventricular assist devices on functional capacity, a randomized controlled trial
Authors: Lilliu Marzia , Onorati Francesco , Luciani Giovanni Battista , Faggian Giuseppe
Published: May 2021

Aims

After the implantation of a left ventricular assist device (LVAD), many patients continue to experience exercise intolerance. VAFRACT trial evaluates the additional benefit of LVAD echo‐guided optimization (EO) on functional capacity (FC), measured by cardiopulmonary exercise test (CPET), and quality of life (QoL).

Methods and results

Twenty‐seven patients were randomized in a 1:1 ratio to EO (EO group) vs. standard settings (CONTROL group) at least after 3 months from LVAD implant procedure. The optimal device speed was defined as the one that allows an intermittent aortic valve opening and a neutral position of the interventricular septum without increasing aortic or tricuspid regurgitation and preserving right ventricular function. The primary endpoint was peak oxygen uptake (VO2 peak) change after 3 months.

Echo‐guided optimization significantly improves VO2 peak (from 13.2 ± 2.5 to 14.2 ± 2.5 mL/kg/min; P < 0.001), oxygen pulse (from 9.75 ± 1.46 to 10.75 ± 2.2 mL; P < 0.001), CPET exercise time (from 490 ± 98 to 526 ± 116 s; P = 0.02), 6 min walk distance (from 363 ± 54 to 391 ± 52 m; P = 0.04), and QoL, using EuroQol Five Dimensions 3L (from 0.796 ± 0.1 to 0.85 ± 0.08; P < 0.001) and the Kansas City Cardiomyopathy Questionnaire (from 81.6 ± 6.9 to 84.6 ± 5.6; P = 0.025).

Conclusions

Echo‐guided optimization can significantly influence the FC and the QoL of LVAD patients. This procedure should represent a fundamental step in their clinical management, through the establishment of consolidated follow‐up protocols. Our study may represent a starting point for a future, adequately powered clinical trial with a longer term follow‐up.
Adaptive anti‐myocardial immune response following hospitalization for acute heart failure
Authors: Morbach Caroline , Beyersdorf Niklas , Kerkau Thomas , Ramos Gustavo , Sahiti Floran , Albert Judith , Jahns Roland , Ertl Georg , Angermann Christiane E. , Frantz Stefan , Hofmann Ulrich , Störk Stefan
Published: May 2021

Aims

It has been hypothesized that cardiac decompensation accompanying acute heart failure (AHF) episodes generates a pro‐inflammatory environment boosting an adaptive immune response against myocardial antigens, thus contributing to progression of heart failure (HF) and poor prognosis. We assessed the prevalence of anti‐myocardial autoantibodies (AMyA) as biomarkers reflecting adaptive immune responses in patients admitted to the hospital for AHF, followed the change in AMyA titres for 6 months after discharge, and evaluated their prognostic utility.

Methods and results

AMyA were determined in n = 47 patients, median age 71 (quartiles 60; 80) years, 23 (49%) female, and 24 (51%) with HF with preserved ejection fraction, from blood collected at baseline (time point of hospitalization) and at 6 month follow‐up (visit F6). Patients were followed for 18 months (visit F18). The prevalence of AMyA increased from baseline (n = 21, 45%) to F6 (n = 36, 77%; P < 0.001). At F6, the prevalence of AMyA was higher in patients with HF with preserved ejection fraction (n = 21, 88%) compared with patients with reduced ejection fraction (n = 14, 61%; P = 0.036). During the subsequent 12 months after F6, that is up to F18, patients with newly developed AMyA at F6 had a higher risk for the combined endpoint of death or rehospitalization for HF (hazard ratio 4.79, 95% confidence interval 1.13–20.21; P = 0.033) compared with patients with persistent or without AMyA at F6.

Conclusions

Our results support the hypothesis that AHF may induce patterns of adaptive immune responses. More studies in larger populations and well‐defined patient subgroups are needed to further clarify the role of the adaptive immune system in HF progression.
Low testosterone concentrations and prediction of future heart failure in men and in women: evidence from the large FINRISK97 study
Authors: Schäfer Sarina , Aydin Muhammet Ali , Appelbaum Sebastian , Kuulasmaa Kari , Palosaari Tarja , Ojeda Francisco , Blankenberg Stefan , Jousilahti Pekka , Salomaa Veikko , Karakas Mahir
Published: May 2021

Aims

The increased incidence of heart failure in men suggests that endogenous sex hormones might play a role in the development of heart failure, but epidemiological data remain sparse. Here, we evaluated the predictive value of low testosterone levels on future heart failure in the large population‐based FINRISK97 study.

Methods and results

Baseline serum testosterone concentrations were measured in 7855 subjects (3865 men and 3990 women) of the FINRISK97 study. During a median follow‐up (FU) of 13.8 years, a total of 564 heart failure events were recorded. The age‐adjusted baseline testosterone levels did not differ significantly between subjects developing incident heart failure during FU and those without incident events during FU (men: 16.6 vs. 17.1 nmol/L, P = 0.75; women: 1.15 vs. 1.17 nmol/L, P = 0.32). Relevant statistically significant correlations of testosterone levels were found with high‐density lipoprotein cholesterol levels (R = 0.22; P < 0.001), body mass index (R = −0.23; P < 0.001), and waist‐to‐hip ratio (R = −0.21; P < 0.001) in men, while statistically significant correlations in women were negligible in effect size. In sex‐stratified Cox regression analyses, taking age into account, a quite strong association between low testosterone and incident heart failure was found in men [hazard ratio (HR) 1.51 (95% confidence interval, CI: 1.09–2.10); P = 0.020 for lowest vs. highest quarter], but not in women [HR 0.70 (95% CI: 0.49–0.98); P = 0.086 for lowest vs. highest quarter]. Nevertheless, this association turned non‐significant after full adjustment including body mass index and waist‐to‐hip ratio, and testosterone levels were no longer predictive for incident heart failure—neither in men [HR 0.99 (95% CI: 0.70–1.42); P = 0.77 for lowest vs. highest quarter] nor in women [HR 0.92 (95% CI: 0.64–1.33); P = 0.99 for lowest vs. highest quarter]. Accordingly, Kaplan–Meier analyses did not reveal significant association of testosterone levels with heart failure.

Conclusions

Low levels of testosterone do not independently predict future heart failure.
Clinical impact of heart rate change in patients with acute heart failure in the early phase
Authors: Kazama Shingo , Kondo Toru , Shibata Naoki , Hiraiwa Hiroaki , Nishiyama Itsumure , Kato Toshiaki , Sawamura Akinori , Kimura Yuki , Oishi Hideo , Kuwayama Tasuku , Morimoto Ryota , Okumura Takahiro , Shimizu Kiyokazu , Murohara Toyoaki
Published: May 2021

Aims

Patients with acute heart failure (AHF) often present with an increased heart rate (HR), and the HR changes dramatically after initial treatment for AHF. However, the HR change after admission and the relationship between HR change in the early phase and prognosis have not been fully elucidated.

Methods and results

From a multicentre AHF registry, we retrospectively evaluated 1527 consecutive patients admitted with AHF. HR change (%) was calculated by [HR (at admission) − HR (24 h after admission)] × 100∕HR (at admission). The median HR change was 15.1% (range, 2.0–28.4%). The HR decreased most in the first 24 h and then gradually thereafter [admission: 98 (81–117) b.p.m., 24 h: 80 (70–92) b.p.m., 48 h: 78 (68–90) b.p.m., and 72 h: 77 (67–88) b.p.m.]. In Kaplan–Meier analysis, the cumulative event‐free rates in the composite endpoint of death and rehospitalization due to AHF showed better according to larger HR change (P = 0.012, log rank). Cox proportional hazards analysis showed that HR change was a prognostic factor for composite endpoint adjusted by age and sex [hazard ratio, 0.995; 95% confidence interval (CI), 0.991–0.998; P = 0.006]. HR change was associated with outcome adjusted by age and sex in patients with sinus rhythm (hazard ratio, 0.993; 95% CI, 0.988–0.999; P = 0.015), but not in patients with atrial fibrillation (hazard ratio, 0.996; 95% CI, 0.990–1.002; P = 0.15).

Conclusions

A decrease in HR in the first 24 h after admission indicates better prognosis in patients with AHF, although the prognostic influence may differ between patients with sinus rhythm and those with atrial fibrillation.
Copper Nanoflowers on Carbon Cloth as a Flexible Electrode Toward Both Enzymeless Electrocatalytic Glucose and H2O2
Authors: Yuan Kun , Zhang Yuchan , Huang Shihao , Yang Shengfei , Zhao Shuang , Liu Fangxin , Peng Qianyu , Zhao Yinping , Zhang Guangyuan , Fan Jingchuan , Zang Guangchao
Published: May 2021

Herein, a novel electrochemical sensor for glucose and hydrogen peroxide (H2O2) detection was successfully developed through the use of Cu nanoflowers (CuNFs) combined with flexible carbon cloth (CC) substrate. The 3D flower‐like CuNFs in size uniformly and firmly grow on CC substrate by a facile, scalable, one‐step hydrothermal strategy. Morphology, size and surface property of the prepared CuNFs/CC were examined by SEM, EDS and TEM, respectively. The electrochemical mechanism of CuNFs/CC for glucose and H2O2 detection was investigated by cyclic voltammetry. High electrochemical performances were displayed with amperometric i‐t curves including a wide linear range from 1.0 nM to 6.0 mM for glucose and from 1.0 μM to 36.66 mM for H2O2, respectively. Good sensitivity, repeatability, and stability, as well as anti‐interference ability, the carbon cloth‐supported CuNFs will be the promising materials for fabricating practical non‐enzymatic glucose and H2O2 sensors.
Highly sensitive and efficient hydrazine sensor probe development based on MoO3/CuO/ZnO ternary mixed metal oxide nano‐composites for sustainable environment
Authors: Subhan Md Abdus , Saha Pallab Chandra , Akand Mohammad Arifur Rahman , Asiri Abdullah M. , Al‐Mamun Mohammad , Rahman Mohammed M.
Published: May 2021

In this study, by using a co‐precipitation method MoO3/CuO/ZnO nanocomposite material was synthesized. Then the prepared material was fully characterized by using XRD (X‐ray diffraction), SEM (scanning electron microscopy), EDS (energy dispersive x‐ray spectroscopy), CV (cyclic voltammetry), and EIS (Electrochemical Impedance Spectroscopy). Zeta potential and hydrodynamic size were measured using a Zetasizer in PBS buffer. By using Scherrer's formula from XRD, particle size was determined which was around 26.5 nm. For the promising chemical sensor development, MoO3/CuO/ZnO nanocomposite material was fabricated onto a glassy carbon electrode (GCE) to provide a sensor probe with a fast response towards the selective hydrazine (HZ) toxin in phosphate buffer phase. The fabricated sensor probe is exhibited good sensitivity and long‐term stability as well as enhanced electrochemical performances. A calibration plot was found linear in the range of 0.2 nM to 2.0 mM (linear dynamic range, LDR) in presence of aqueous HZ solutions with highest sensitivity value and lower limit of detection and good limit of quantification (LOQ). This approach is promising as an efficient technique in developing a highly effective sensor probe with ternary metal oxides for detecting environmental pollutants on a broad scale.
Optimization of gamma‐aminobutyric acid production by Lactobacillus brevis PML1 in dairy sludge‐based culture medium through response surface methodology
Authors: Falah Fereshteh , Vasiee Alireza , Alizadeh Behbahani Behrooz , Tabatabaee Yazdi Farideh , Mortazavi Seyed Ali
Published: May 2021

Gamma‐aminobutyric acid (GABA) is a pharmaceutical, bioactive amino acid that can produce by some species of Lactic Acid Bacteria (LAB). For the first time, we evaluated the production of GABA by Lactobacillus brevis PML1 in the medium that contain the contaminant food bio‐product like dairy sludge and soybean meal. GABA production was analyzed by chromatography (TLC, HPLC) and the features of fermented extract which contains this amino acid were evaluated. The results of Response Surface Methodology (RSM) of Central Composite Design (CCD) at p < .05 showed 300 ppm of GABA production in optimal treatment including 14.77% dairy sludge powder, 6.27% soybean meal, and 0.49% ammonium sulfate (32°C for 120 hr fermentation). The results of fermented extract also showed the acceptable antimicrobial, antioxidant, and toxicity (against cancer cell) properties. Also, L. brevis PML1has not shown any hemolytic or DNase activity which confirm its safety aspects. According to the results, this new culture can be used as a cheap substrate to biological production of GABA, by L. brevis PML1 in various food and pharmaceutical formulations.
Efficiency in the Atlantic salmon futures market
Authors: Andersen Bendik P. , de Lange Petter E.
Published: May 2021

In this study, we examine the efficiency and unbiasedness of Atlantic salmon futures prices. Market participants use the Fish Pool futures market to hedge the increasingly volatile salmon spot price. We further examine the futures market's predictive accuracy, comparing it to a variety of proprietary prediction models. Our results show that futures prices are efficient and unbiased in the long‐run, while being biased and inefficient in the short‐run. Moreover, we find that futures prices provide an adequate price discovery function for most contracts, while suffering from magnified risk premiums due to few noncommercial traders.
Determining the origin and changing shape of landscape‐scale rock formations with three‐dimensional modelling: The Borologa rock shelters, Kimberley region, Australia
Authors: Genuite Kim , Delannoy Jean‐Jacques , David Bruno , Unghango Augustine , Corporation Balanggarra Aboriginal , Cazes Gaël , Fulop Reka , Fink David , Codilean Alexandru , Ouzman Sven , Veth Peter , Harper Sam , Green Helen , Finch Damien , Urwin Chris
Published: May 2021

Archaeologists often wonder how and when rock shelters formed, yet their origins and antiquity are almost never systematically investigated. Here we present a new method to determine how and when individual boulders and rock shelters came to lie in their present landscape settings. We do so through 3D laser (LiDAR) mapping, illustrating the method by example of the Borologa Aboriginal site complex in the Kimberley region of northwestern Australia. Through a combination of geomorphological study and high‐resolution 3D modelling, individual blocks of rock are refitted and repositioned t680their originating cliff‐line. Preliminary cosmogenic nuclide ages on exposed vertical cliff faces and associated detached boulders above the Borologa archaeological sites signal very slow detachment rates for the mass movements of large blocks down the Drysdale Valley slopes, suggesting relative landscape stability over hundreds of thousands of years (predating the arrival of people). These findings offer hitherto unknown details of the pace of regional landscape evolution and move us toward a better understanding of patterns of human occupation in a context of relatively stable rock outcrops both within the sites and across the region.
Haploinsufficiency of microglial MyD88 ameliorates Alzheimer's pathology and vascular disorders in APP/PS1‐transgenic mice
Authors: Quan Wenqiang , Luo Qinghua , Hao Wenlin , Tomic Inge , Furihata Tomomi , Schulz‐Schäffer Walter , Menger Michael D. , Fassbender Klaus , Liu Yang
Published: May 2021

Growing evidence indicates that innate immune molecules regulate microglial activation in Alzheimer's disease (AD); however, their effects on amyloid pathology and neurodegeneration remain inconclusive. Here, we conditionally deleted one allele of myd88 gene specifically in microglia in APP/PS1‐transgenic mice by 6 months and analyzed AD‐associated pathologies by 9 months. We observed that heterozygous deletion of myd88 gene in microglia decreased cerebral amyloid β (Aβ) load and improved cognitive function of AD mice, which was correlated with reduced number of microglia in the brain and inhibited transcription of inflammatory genes, for example, tnf‐α and il‐1β, in both brain tissues and individual microglia. To investigate mechanisms underlying the pathological improvement, we observed that haploinsufficiency of MyD88 increased microglial recruitment toward Aβ deposits, which might facilitate Aβ clearance. Microglia with haploinsufficient expression of MyD88 also increased vasculature in the brain of APP/PS1‐transgenic mice, which was associated with up‐regulated transcription of osteopontin and insulin‐like growth factor genes in microglia. Moreover, MyD88‐haploinsufficient microglia elevated protein levels of LRP1 in cerebral capillaries of APP/PS1‐transgenic mice. Cell culture experiments further showed that treatments with interleukin‐1β decreased LRP1 expression in pericytes. In summary, haploinsufficiency of MyD88 in microglia at a late disease stage attenuates pro‐inflammatory activation and amyloid pathology, prevents the impairment of microvasculature and perhaps also protects LRP1‐mediated Aβ clearance in the brain of APP/PS1‐transgenic mice, all of which improves neuronal function of AD mice.
Microglia‐mediated phagocytosis of apoptotic nuclei is impaired in the adult murine hippocampus after stroke
Authors: Rudolph Max , Schmeer Christian W. , Günther Madlen , Woitke Florus , Kathner‐Schaffert Carolin , Karapetow Lina , Lindner Julia , Lehmann Thomas , Jirikowski Gustav , Witte Otto W. , Redecker Christoph , Keiner Silke
Published: May 2021

Following stroke, neuronal death takes place both in the infarct region and in brain areas distal to the lesion site including the hippocampus. The hippocampus is critically involved in learning and memory processes and continuously generates new neurons. Dysregulation of adult neurogenesis may be associated with cognitive decline after a stroke lesion. In particular, proliferation of precursor cells and the formation of new neurons are increased after lesion. Within the first week, many new precursor cells die during development. How dying precursors are removed from the hippocampus and to what extent phagocytosis takes place after stroke is still not clear. Here, we evaluated the effect of a prefrontal stroke lesion on the phagocytic activity of microglia in the dentate gyrus (DG) of the hippocampus. Three‐months‐old C57BL/6J mice were injected once with the proliferation marker BrdU (250 mg/kg) 6 hr after a middle cerebral artery occlusion or sham surgery. The number of apoptotic cells and the phagocytic capacity of the microglia were evaluated by means of immunohistochemistry, confocal microscopy, and 3D‐reconstructions. We found a transient but significant increase in the number of apoptotic cells in the DG early after stroke, associated with impaired removal by microglia. Interestingly, phagocytosis of newly generated precursor cells was not affected. Our study shows that a prefrontal stroke lesion affects phagocytosis of apoptotic cells in the DG, a region distal to the lesion core. Whether disturbed phagocytosis might contribute to inflammatory‐ and maladaptive processes including cognitive impairment following stroke needs to be further investigated.
Bayesian estimation of maximum entropy model for individualized energy landscape analysis of brain state dynamics
Authors: Kang Jiyoung , Jeong Seok‐Oh , Pae Chongwon , Park Hae‐Jeong
Published: May 2021

The pairwise maximum entropy model (MEM) for resting state functional MRI (rsfMRI) has been used to generate energy landscape of brain states and to explore nonlinear brain state dynamics. Researches using MEM, however, has mostly been restricted to fixed‐effect group‐level analyses, using concatenated time series across individuals, due to the need for large samples in the parameter estimation of MEM. To mitigate the small sample problem in analyzing energy landscapes for individuals, we propose a Bayesian estimation of individual MEM using variational Bayes approximation (BMEM). We evaluated the performances of BMEM with respect to sample sizes and prior information using simulation. BMEM showed advantages over conventional maximum likelihood estimation in reliably estimating model parameters for individuals with small sample data, particularly utilizing the empirical priors derived from group data. We then analyzed individual rsfMRI of the Human Connectome Project to show the usefulness of MEM in differentiating individuals and in exploring neural correlates for human behavior. MEM and its energy landscape properties showed high subject specificity comparable to that of functional connectivity. Canonical correlation analysis identified canonical variables for MEM highly associated with cognitive scores. Inter‐individual variations of cognitive scores were also reflected in energy landscape properties such as energies, occupation times, and basin sizes at local minima. We conclude that BMEM provides an efficient method to characterize dynamic properties of individuals using energy landscape analysis of individual brain states.
Neural representations of the amount and the delay time of reward in intertemporal decision making
Authors: Wang Qiang , Wang Yajie , Wang Pinchun , Peng Maomiao , Zhang Manman , Zhu Yuxuan , Wei Shiyu , Chen Chuansheng , Chen Xiongying , Luo Shan , Bai Xuejun
Published: May 2021

Numerous studies have examined the neural substrates of intertemporal decision‐making, but few have systematically investigated separate neural representations of the two attributes of future rewards (i.e., the amount of the reward and the delay time). More importantly, no study has used the novel analytical method of representational connectivity analysis (RCA) to map the two dimensions' functional brain networks at the level of multivariate neural representations. This study independently manipulated the amount and delay time of rewards during an intertemporal decision task. Both univariate and multivariate pattern analyses showed that brain activity in the dorsomedial prefrontal cortex (DMPFC) and lateral frontal pole cortex (LFPC) was modulated by the amount of rewards, whereas brain activity in the DMPFC and dorsolateral prefrontal cortex (DLPFC) was modulated by the length of delay. Moreover, representational similarity analysis (RSA) revealed that even for the regions of the DMPFC that overlapped between the two dimensions, they manifested distinct neural activity patterns. In terms of individual differences, those with large delay discounting rates (k) showed greater DMPFC and LFPC activity as the amount of rewards increased but showed lower DMPFC and DLPFC activity as the delay time increased. Lastly, RCA suggested that the topological metrics (i.e., global and local efficiency) of the functional connectome subserving the delay time dimension inversely predicted individual discounting rate. These findings provide novel insights into neural representations of the two attributes in intertemporal decisions, and offer a new approach to construct task‐based functional brain networks whose topological properties are related to impulsivity.