A general model for the origin of allometric scaling laws in biology

Relationships between leaf morphologies and stomatal traits of Achnatherum splendens under different soil moistures in semiarid Northern China

The interplay between leaf and stomata is fundamental for the exchange of carbon and water between plants and the atmosphere. This relationship is pivotal for comprehending the connections between the physical structure and physiological metabolism of plant leaves under various conditions. A study examining the relationship between leaf morphological traits and stomatal traits of the Achnatherum splendens under varying natural soil moisture conditions was conducted along the southern shore of Hulun Lake in Inner Mongolia. In our study, stomatal density (SD) and stomatal relative area (SRA) significantly decreased, while stomatal width (SW), leaf length (LL), leaf area (LA) and leaf dry weight (LDW) increased correspondingly with rising soil moisture. A significant positive correlation between the stomatal traits and leaf morphological traits was observed through principal component analysis (PCA) and permutation test, indicating that the functional traits of leaf morphologies and stomata of A. splendens exhibit a positive relationship. The results reveal the resource utilization strategies of A. splendens in response to varying soil water conditions, offering a scientific data foundation and theoretical support for the management of A. splendens grassland, ecological restoration, and the strategic planning of animal husbandry in Inner Mongolia.

Establishment of cell size-dependent growth rate via differential scaling of metabolite uptake and release

Metabolism fuels cell growth and functions. While it is well established that cellular growth rate scales with cell size, how cells alter their metabolism as they change size remains largely unexplored. Here, we conducted a systematic analysis of cell size-dependent metabolism across the NCI60 cancer cell line panel comprising a diverse range of cell sizes. We demonstrate that cellular metabolism and growth rate display 2/3 allometric scaling due to differential scaling of overall nutrient uptake and waste metabolite release with respect to cell size, with waste elimination decreasing less rapidly than nutrient uptake rate as cells grow larger. This results in cell size-dependent growth rate and predicts a maximum cell size where net nutrient uptake equals zero and cell enlargement ceases despite active metabolism. We experimentally confirm this prediction and identify that electron acceptor demand constrains cell enlargement as evidenced by depletion of intracellular aspartate and scaling of aspartate uptake, which is more than proportional to cell volume. Overall, these findings may have implications for understanding cell size homeostasis, developmental biology, and the design principles of living organisms.

Metabolic scaling: exploring the relation between metabolic rate and body size

We present an alternative to the traditional classroom lecture on the topics of metabolic scaling, allometric relationships between metabolic rate (MR) and body size, and reasons for rejecting Rubner's surface "law," concepts that students have described as challenging, counterintuitive, and/or mathematical. In groups, students work with published data on MR and body size for species representing all five vertebrate groups. To support the exercise, we developed a worksheet that has students define the concept in their own words, compare different measures of MR, and evaluate plots of MR and mass-specific MR vs. body mass for both homeotherms and poikilotherms. Students also attempt to explain why selected species have exceptionally high or low MR values for their body sizes. Student feedback indicated that active learning is an effective way to learn the concepts of metabolic scaling and allometric relationships and that the opportunity to work in groups with real data stimulates interest and an appreciation for the importance of metabolic scaling to the understanding of animal physiology.NEW & NOTEWORTHY Here we describe a worksheet that we designed for a group exercise in which students study real data to learn about metabolic scaling in different groups of vertebrates, understand that metabolic rates are allometric functions of body size, and consider why physiologists now reject Rubner's surface "law." We used this exercise in a course in animal physiology in place of the traditional lecture approach to teaching the concept of metabolic scaling.

Developing mixed-effects aboveground biomass model using biotic and abiotic variables for moso bamboo in China

Moso bamboo forests, which are distributed across southern China, have played the important roles in the global carbon cycle and contribute significantly to mitigating the impacts of climate change. Previous studies on moso bamboo have focused mainly on the impacts of climate change and competition intensity on aboveground biomass (AGB), ignoring the effects of soil and topographic factors on the allometric relationships between biomass and bamboo structural variables and carbon allocation to different geographical regions. This study applied a mixed-effects modeling approach to analyze AGB data acquired from the destructive sampling and measurements of 306 moso bamboo individuals in southern China. The power function was used to develop a two-level (growth region [province]- and elevation-levels) mixed-effects AGB model with diameter of breast height (DBH), topography, climate, and soil characteristics used as predictor variables. Variations of AGB caused by differences of growth regions and elevations were described by random components in the model. The results showed that environmental heterogeneity across growth regions led to substantial differences in the scaling exponent of the power function. Incorporating DBH, height (H), the de Martonne aridity index, sine of the slope combined with the natural logarithm of elevation, sand, and rock fragment (RF) (soil) into the AGB model significantly improved its prediction performance. Increasing DBH, H, soil RF, and precipitation and reducing soil sand fraction to a certain extent showed beneficial effects on moso bamboo AGB accumulation. The model reveals strong relationships between AGB and bamboo structural variables, topography, climate, and soil factors. The model will be useful for developing bamboo forest management strategies in line with the environmental changes, and can offer a novel approach for carbon accounting in the context of climate change.

JE, Andrade Jr. JS, Furtado V. The US Caselaw as a living system

This study presents an innovative exploration of the American Caselaw database, encompassing more than five million legal cases spanning three centuries of American history. Using complex network analysis, we reveal the organic nature of the US Caselaw, fundamentally anchored in common law. Through analysis of citation and bibliographic coupling networks, we shed light on the system's internal structure, unveiling communities delineated by regional, federal jurisdiction, and clustering based on similar legal citations. Our research uncovers a remarkable allometric relationship between the activity of judges and the legal case citations, reflecting the analogy between metabolic rate and body mass correlation observed in biological organisms. Furthermore, our results show a consistent self-similar characteristics of the communities and their maximum spanning trees, which also provides relevant insight into the origin of the allometric behavior. This analysis not only reveals the US Caselaw as a "living" entity but also sets a precedent in Caselaw-based judicial system studies, reinforcing the notion of its dynamic, organic functionality in the realm of analyzing complex legal systems.

Evaluating Tranexamic Acid Dosing Strategies for Postpartum Hemorrhage: A Population Pharmacokinetic Approach in Pregnant Individuals

Tranexamic acid (TXA) is used for the treatment and occasionally prevention of postpartum hemorrhage (PPH); however, questions still remain regarding dosing regimen optimization. This study evaluated TXA pharmacokinetic (PK) data from four clinical trials (NCT: 04274335, 03287336, 00872469, and 02797119) conducted in pregnant participants receiving intravenous, intramuscular, or oral TXA to prevent or treat PPH. The goal of this analysis was to comprehensively characterize TXA PK in a large, heterogeneous population of pregnant individuals to (1) assess the need for weight-based dosing and (2) compare exposure target attainment for alternative routes of administration. A population PK analysis was performed using nonlinear mixed-effects modeling in Pumas, and a stepwise approach was implemented to select the structural model and identify significant covariates. A total of 211 pregnant participants who received between 0.35 and 4 g of TXA intravenously, orally, or intramuscularly offered 1303 TXA plasma concentrations for model development. A two-compartment model with first-order elimination and first-order absorption for both intramuscular and oral administration best described the disposition of TXA. Actual body weight was the only statistically significant covariate identified, but inclusion into the model did not explain a substantial amount of the observed variability. Simulations of virtual pregnant individuals indicated minimal differences in TXA exposure between fixed and weight-based dosing regimens, supporting the use of fixed dosing. Intramuscular TXA was additionally found to be a viable alternative to intravenous administration, achieving similar target exposure metrics.

High-order interaction modeling of tumor-microenvironment crosstalk for tumor growth

Signaling interactions between cancer cells and nonmalignant cells in the tumor microenvironment (TME) are believed to influence tumor progression and drug resistance. However, the genomic machineries mediating such an influence remain elusive, making it difficult to determine therapeutic targets on the tumor and its microenvironment. Here, we argue that a computational model, derived from the integration of evolutionary game theory and ecosystem theory through allometric scaling law, can chart the genomic atlas of high-order interaction networks involving tumor cells, TME, and tumor mass. We assess the application of this model to identify the causal influence of gene-induced tumor-TME crosstalk on tumor growth. The findings demonstrate that cooperation and competition between tumor cells and their infiltrating microenvironment promote or inhibit tumor growth in diverse ways. We identify specific genes that govern this promotion or inhibition, which can be used as genetic targets to alter tumor growth. This model opens up a new avenue to precisely infer the genomic underpinnings of tumor-TME interactions and their impact on tumor progression from any omics data.

The effect of psychedelic microdosing on animal behavior: A review with recommendations for the field

Microdosing, the repeated use of psychedelic substances at low doses, is growing in popularity among recreational consumers. While this practice is associated with many benefits to mood, well-being and health, research in this area is in its early stages and predominantly centered on human applications. In this narrative review, we synthesize the findings from studies investigating the effects of microdosing on the behaviors of three animal species: rats, mice, and zebrafish. A total of 12 studies were identified that implemented a microdosing regimen of LSD, psilocybin, or DMT in these animal models. Overall, microdosing caused little changes in behaviors associated with anxiety- and depressive-like states. Moreover, while microdosing was well-tolerated across species, further research is needed to capture specific safety concerns. Finally, we critically appraise the studies included in this review based on their methodologies and discuss further avenues of research to advance the preclinical literature on psychedelic microdosing. Specifically, we recommend that future research prioritize the replication of existing findings to inform the development of robust study designs and dosing protocols, as well as establish standardized methodologies to enable effective comparisons across different animal models. Furthermore, future investigations should explore the therapeutic potential of mescaline microdosing, examine sex-dependent effects, and extend research to additional models of psychiatric conditions, including those related to obsessive-compulsive disorder and post-traumatic stress disorder.

A translational physiologically-based pharmacokinetic model for MMAE-based antibody-drug conjugates

The objective of this work was to develop a translational physiologically-based pharmacokinetic (PBPK) model for antibody-drug conjugates (ADCs), using monomethyl auristatin E (MMAE)-based ADCs. A previously established dual-structured whole-body PBPK model for MMAE-based ADCs in mice was scaled to higher species (i.e., rats and monkeys) and humans. Species-specific physiological and drug-related parameters for the payload and antibody backbone of ADCs were obtained from literature. Parameters associated with payload release, including the deconjugation rate, were optimized using an allometric scaling approach, and antibody degradation rate was adjusted to account for the enhanced clearance of ADCs due to conjugation across different species. The translational PBPK model predicted the PK profiles for various ADC analytes in rats, monkeys, and humans reasonably well. The optimized PBPK model suggested decreased rate of deconjugation for ADCs in higher species, whereas the effects of payload conjugation on ADC clearance were more pronounced in higher species and humans. The translational PBPK model presented here may enable prediction of different ADC analyte PK at the site-of-action, offering valuable insights for the development of exposure-response relationships for ADCs. The modeling framework presented here can also serve as a platform for the development of PBPK model for other ADCs.

Episodic body size variations of early Paleozoic trilobites associated with marine redox changes

Body size greatly affects how organisms interact with their environments. However, the macroevolutionary patterns of body size across many major metazoan clades and their constraining mechanisms remain elusive. A new high-resolution body size dataset covering 2435 species from 1091 genera of Cambrian and Ordovician trilobites reveals that body size evolution changes episodically, with three marked reductions in size. Such a pattern rules out a persistent Cope's rule dynamic. Rather, we find a strong temporal link between body size changes and major fluctuations in marine redox, supporting the hypothesis that marine oxygen levels exerted a primary control on the tempo and mode of trilobite body size evolution. These further imply a dominant role for marine oxygen in early animal evolution.

Utilizing dried blood spot micro-sampling and population pharmacokinetic modelling and simulation to inform ampicillin dosing in Chinese neonates

OBJECTIVES

Ampicillin, a β-lactam antibiotic frequently prescribed for bacterial infections, is used off-label in neonates. Blood sampling limitations in neonatal pharmacokinetic (PK) studies make dried blood spots (DBS) a promising matrix for micro-sampling. This study aims to develop a population PK (PopPK) model using a DBS-based approach to optimize ampicillin dosing in Chinese neonatal patients.

METHODS

DBS samples were collected at predefined intervals from neonatal patients after ampicillin dosing. A PopPK model was developed using NONMEM 7.5, followed by model-based simulations to provide dosing recommendations in virtual population. During the simulations, the predicted blood concentrations were converted to unbound plasma concentrations using a blood-to-plasma ratio of 0.56 and an unbound fraction of 0.8. The PK/pharmacodynamic (PD) target was 100% of the time with the unbound drug plasma concentration above the MIC (%fT > MIC), and the risk of toxicity threshold was defined as a steady-state peak plasma concentration exceeding 140 mg/L.

RESULTS

Data from 53 patients with 102 DBS samples were collected, and the ranges of body weight and postmenstrual age (PMA) were 1.91-4.25 kg and 34.3-41.4 weeks, respectively. Ampicillin PK were characterized using a one-compartment model with first-order elimination. An allometric scaling and renal maturation model were integrated into the model to describe the developmental PK in hospitalized neonates. Simulations suggest that the optimal dosing regimen is 25 mg/kg administered intravenously every 6 h across PMA of 32-42 weeks.

CONCLUSIONS

We successfully developed a PopPK model of ampicillin using DBS sampling for Chinese neonates and proposed evidence-based dosing recommendations.

Same with less: a method to reduce destructive sampling to estimate nitrogen use efficiency components using allometric relationships in spring wheat (Triticum aestivum)

Enhancing nitrogen (N) use efficiency is important for a sustainable food production. Measuring shoot biomass and N pool across growth stages is critical to calculate N use efficiency, but relies on slow, costly and destructive sampling. This paper presents a non-destructive allometric approach developed for cereals; in this study, we assessed wheat (Triticum aestivum ) for crop shoot biomass and N pool. Our methodology considered tiller height and number, and the estimates of leaf chlorophyll content (SPAD) as non-destructive measures to predict shoot biomass and N pool by using a multiple linear and a non-linear regression (R 2 =0.71 and R 2 =0.89, respectively) on the data from 72 samples of 16 recombinant inbred spring wheat lines (RILs) field-grown in central Sweden during 2years with contrasting weather. Model parameters are estimated separately for different years to accommodate environmental variations between them. The regressions obtained were applied to estimate critical N use efficiency traits of 80 randomly selected wheat lines from the same RIL population. The method developed here provides a promising novel tool for the cost-effective estimation of critical N use efficiency parameters in cereals, with reduced destructive sampling, and a first step toward automated phenotyping for rapid N use efficiency assessment in cereal breeding populations.

Accelerated signal propagation speed in human neocortical dendrites

Human-specific cognitive abilities depend on information processing in the cerebral cortex, where the neurons are significantly larger and their processes longer and sparser compared to rodents. We found that, in synaptically connected layer 2/3 pyramidal cells (L2/3 PCs), the delay in signal propagation from soma to soma is similar in humans and rodents. To compensate for the longer processes of neurons, membrane potential changes in human axons and/or dendrites must propagate faster. Axonal and dendritic recordings show that the propagation speed of action potentials (APs) is similar in human and rat axons, but the forward propagation of excitatory postsynaptic potentials (EPSPs) and the backward propagation of APs are 26 and 47% faster in human dendrites, respectively. Experimentally-based detailed biophysical models have shown that the key factor responsible for the accelerated EPSP propagation in human cortical dendrites is the large conductance load imposed at the soma by the large basal dendritic tree. Additionally, larger dendritic diameters and differences in cable and ion channel properties in humans contribute to enhanced signal propagation. Our integrative experimental and modeling study provides new insights into the scaling rules that help maintain information processing speed albeit the large and sparse neurons in the human cortex.

Ecology: Why failure is success for an ecological theory

A theory-derived ecological equation of state relating biodiversity, productivity, abundance and biomass in ecosystems has been tested with satellite-derived proxy forestry data. Predicted failure of the relationship in disturbed ecosystems is partially supported but further ground-based analysis is needed.

Does death drive the scaling of life?

The magnitude of many kinds of biological structures and processes scale with organismal size, often in regular ways that can be described by power functions. Traditionally, many of these "biological scaling" relationships have been explained based on internal geometric, physical, and energetic constraints according to universal natural laws, such as the "surface law" and "3/4-power law". However, during the last three decades it has become increasingly apparent that biological scaling relationships vary greatly in response to various external (environmental) factors. In this review, I propose and provide several lines of evidence supporting a new ecological perspective that I call the "mortality theory of ecology" (MorTE). According to this viewpoint, mortality imposes time limits on the growth, development, and reproduction of organisms. Accordingly, small, vulnerable organisms subject to high mortality due to predation and other environmental hazards have evolved faster, shorter lives than larger, more protected organisms. A MorTE also includes various corollary, size-related internal and external causative factors (e.g. intraspecific resource competition, geometric surface area to volume effects on resource supply/transport and the protection of internal tissues from environmental hazards, internal homeostatic regulatory systems, incidence of pathogens and parasites, etc.) that impact the scaling of life. A mortality-centred approach successfully predicts the ranges of body-mass scaling slopes observed for many kinds of biological and ecological traits. Furthermore, I argue that mortality rate should be considered the ultimate (evolutionary) driver of the scaling of life, that is expressed in the context of other proximate (functional) drivers such as information-based biological regulation and spatial (geometric) and energetic (metabolic) constraints.

Exploring the Evolution-Coupling Hypothesis: Do Enzymes' Performance Gains Correlate with Increased Dissipation?

The research literature presents divergent opinions regarding the role of dissipation in living systems, with views ranging from it being useless to it being essential for driving life. The implications of universal thermodynamic evolution are often overlooked or considered controversial. A higher rate of entropy production indicates faster thermodynamic evolution. We calculated enzyme-associated dissipation under steady-state conditions using minimalistic models of enzyme kinetics when all microscopic rate constants are known. We found that dissipation is roughly proportional to the turnover number, and a log-log power-law relationship exists between dissipation and the catalytic efficiency of enzymes. "Perfect" specialized enzymes exhibit the highest dissipation levels and represent the pinnacle of biological evolution. The examples that we analyzed suggested two key points: (a) more evolved enzymes excel in free-energy dissipation, and (b) the proposed evolutionary trajectory from generalist to specialized enzymes should involve increased dissipation for the latter. Introducing stochastic noise in the kinetics of individual enzymes may lead to optimal performance parameters that exceed the observed values. Our findings indicate that biological evolution has opened new channels for dissipation through specialized enzymes. We also discuss the implications of our results concerning scaling laws and the seamless coupling between thermodynamic and biological evolution in living systems immersed in out-of-equilibrium environments.

Wind speed and soil properties drive the height-diameter allometric pattern of island plants

Introduction

Island ecosystems, due to their geographical isolation and unique environmental conditions, often serve as natural laboratories for ecological research and are also sensitive to global climate change and biodiversity loss. The allometric relationship between plant height-diameter reflects the adaptive growth strategy of plants under different environmental conditions, particularly in response to biomechanical constraints (e.g., wind resistance) and resource availability. This study aims to explore the key driving factors of the height-diameter allometry of island plants, focusing on how island area, soil properties, and climatic factors (e.g., wind speed, temperature, and precipitation) affect plant growth strategy.

Methods

We analyzed plant data from 20 tropical islands, using SMA regression to calculate the allometric exponent and intercept for each island's plants, and evaluated the effects of island area, soil properties, and climatic factors (wind speed, temperature, and precipitation) on the height-diameter allometric relationship.

Results

The results show that island area has no significant effect on plant allometry, while climatic factors, particularly wind speed, and soil properties significantly influence the allometric exponent and intercept, respectively. Specifically, wind speed is the primary driver of the height-diameter allometric exponent, regulating plant growth proportions through mechanical stress and canopy limitation. In contrast, soil properties predominantly govern changes in the allometric intercept, reflecting their critical role in determining baseline growth conditions, such as resource allocation and initial morphological adaptation. The effects of temperature and precipitation are relatively weak, likely due to the buffering effects of the tropical climate and marine moisture supplementation.

Discussion

Overall, this study highlights the key roles of wind speed and soil in shaping the allometry of island plants, providing new insights into the adaptive strategies of island plants under resource limitations and climatic pressures, as well as offering important scientific evidence for island ecological conservation and restoration.

Functionality of photobiological traits of the giant kelp (Macrocystis pyrifera) as key determinant to thrive in contrasting habitats in a sub-Antarctic region

Because of its large size and foundational role, the form and function of the giant kelp Macrocystis pyrifera define key responses to the environmental shifts and ecosystem services. The present study compared several morphological, bio-optical and fluorescence-based photobiological traits as well biomass allocation patterns of the kelp in three sites with different environmental settings along the west coast of the sub-Antarctic strait of Magellan. The morpho-functional and bio-optical characteristics of the algae varied between the sites, following differences in underwater light and tidal range between Atlantic (Buque Quemado and San Gregorio) and Pacific (Bahía Buzos) sectors. Traits measured in blades and individual thalli contributed differently to the total variability within the giant kelp populations. The individuals from the intertidal muddy flats from Buque Quemado differed in many traits, especially biomass allocation along the thallus and bio-optics, with respect to the subtidal rocky assemblages from San Gregorio and especially Bahía Buzos. Photosynthetic characteristics revealed shade adaptation with Ek values normally ≤400 μmol m-2 s-1. In San Gregorio, a site with lower water transparency, light requirements coincide with irradiances at depths between 11 and 4 m, while Ek values estimated for Bahía Buzos indicated photosynthesize at depths >20 m.

Ecophysical constraints on avian adaptation and diversification

The evolution of morphological diversity is ultimately governed by physical laws and ecological contexts, which together impose a range of ecophysical constraints. Substantial progress has been made in identifying how these constraints shape the form and function of producers (plants), but similar knowledge is lacking for consumers, in part because the requisite data have not been available at sufficient scale for animals. Using morphometric measurements for all birds, we demonstrate that observed variation is restricted-both for beak shape and body shape-to triangular regions of morphospace with clearly defined boundaries and vertices (corners). By combining morphometric data with information on ecological and behavioral functions, we provide evidence that the extent of avian morphospace reflects a trade-off between three fundamental physical tasks for feeding (crush, engulf, and reach) that characterize resource acquisition and processing by the beak and three physical tasks (fly, swim, and walk) that characterize avian lifestyles or locomotion. Phylogenetic analyses suggest that trajectories of morphological evolution trend toward the vertices, with lineages evolving from a core of functional generalists toward more specialized physical tasks. We further propose that expansion beyond the current boundaries of morphospace is constrained by the shorter evolutionary lifespan of functional specialists, although patterns of speciation rate and current extinction risk provide only weak support for this hypothesis. Overall, we show that the structure of avian morphospace follows relatively simple rules defined by ecophysical constraints and trade-offs, shedding light on the processes shaping modern animal diversity and responses to environmental change.

Macroecological rules predict how biomass scales with species richness in nature

Despite advances in theory and experiments, how biodiversity influences the structure and functioning of natural ecosystems remains debated. By applying new theory to data on 84,695 plant, animal, and protist assemblages, we show that the general positive effect of species richness on stocks of biomass, as well as much of the variation in the strength and sign of this effect, is predicted by a fundamental macroecological quantity: the scaling of species abundance with body mass. Standing biomass increases with richness when large-bodied species are numerically rare but is independent of richness when species size and abundance are uncoupled. These results suggest a new fundamental law in the structure of ecological communities and show that the impacts of changes in species richness on biomass are predictable.

Large-Scale Compartmental Model-Based Study of Preclinical Pharmacokinetic Data and Its Impact on Compound Triaging in Drug Discovery

Reliable and robust human dose prediction plays a pivotal role in drug discovery. The prediction of human dose requires proper modeling of preclinical intravenous (IV) pharmacokinetic (PK) data, which is usually achieved either through noncompartmental analysis (NCA) or compartmental analysis. While NCA is straightforward, it loses valuable information about the shape of the PK curves. In contrast, compartmental analysis offers a more comprehensive interpretation but poses challenges in scaling up for high-throughput applications in discovery. To address this challenge, we developed computational frameworks, termed compartmental PK (CPK) and automated dose prediction (ADP), to enable automated compartmental model-based IV PK data modeling, translation, and simulation for human dose prediction in compound triaging and optimization. With CPK and ADP, we analyzed compounds with data collected at the MRL between 2013 and 2023 to quantitatively characterize the impact of different PK modeling and simulation methods on human dose prediction. Our study revealed that despite minimal impact on estimating animal PK parameters, different methods significantly impacted predicted human dose, exposure, and Cmax, driven more by different simulation assumptions than by the PK modeling itself. CPK-ADP therefore enables us to efficiently perform complex human dose predictions on a large scale while integrating the latest and best information available on absorption, distribution, and clearance to support decision-making in discovery.

Metabolic ecology in aquatic ecosystems: Viewed from trophic compartments and communities in food webs

A different perspective in metabolic ecology is presented using food web data, based on trophic compartments and communities in aquatic ecosystems (coastal areas, shelves and estuaries in marine ecosystems, and lake ecosystems), including primary producers (phytoplankton and aquatic plants). The relationships among the metabolic traits (biomass, respiration and production) in aquatic communities are expressed through power laws, hence, the value of one of the three metabolic traits provides the values of the other two. Noteworthily, these metabolic traits (biomass, respiration, production) are related to those of primary producers according to various power laws. That is: the metabolic traits of communities can be estimated from those of primary producers alone. These power laws appear to be universal in marine ecosystems but vary among different lake ecosystems.

Association of Murray's law with atherosclerosis risk: Numerical validation of a general scaling law of arterial tree

Atherogenesis is prone in medium and large-sized vessels, such as the aorta and coronary arteries, where hemodynamic stress is critical. Low and oscillatory wall shear stress contributes significantly to endothelial dysfunction and inflammation. Murray's law minimizes energy expenditure in vascular networks and applies to small arteries. However, its assumptions fail to account for the pulsatile nature of blood flow in larger, atherosclerosis-prone arteries. This study aims to numerically validate a novel general scaling law that extends Murray's law to incorporate pulsatile flow effects and demonstrate its applications in vascular health and artificial graft design. The proposed scaling law establishes an optimal relationship between arterial bifurcation characteristics and pulsatile flow dynamics, applicable throughout the vascular system. This work examines the relationship between deviations from Murray's law and the development of atherosclerosis in both coronary arteries and abdominal aorta bifurcations, explaining observed deviations from Murray's law in these regions. A finite volume method is applied to evaluate flow patterns in coronary arteries and aortoiliac bifurcations, incorporating in vivo pulsatile inflow and average outlet pressure. The results indicate that the proposed scaling law enhances wall shear stress distribution compared to Murray's law, which is characterized by higher wall shear stress and reduced oscillatory shear index. These findings suggest that vessels adhering to this scaling law are less susceptible to atherosclerosis. Furthermore, the results are consistent with clinical morphometric data, underscoring the potential of the proposed scaling law to optimize vascular graft designs, promoting favorable hemodynamic patterns and minimizing the occlusion risk in clinical applications.

Reproductive success of inbred strain MV31 of the ctenophore Mnemiopsis leidyi in a self-sustaining inland laboratory culture system

Ctenophores are an attractive phylogenetic lineage for studying animal evolution due to their early divergence from other metazoans. Among Ctenophora, Mnemiopsis leidyi is a model system for developmental, cellular, molecular genetic, and evolutionary studies. Until recently, many of these studies were conducted on wild-caught animals, limiting access to researchers on the coast. Here we present significant advancements towards culturing M. leidyi in laboratories without coastal access, enabling its wider use as an experimental and genetic model system. We detail updated feeding regimens that take advantage of co-culturing Brachionus rotifers with Apocyclops copepods, and quantify the reproductive output of our M. leidyi lab strain on this diet. Our updated feeding regimen maintains reproductive fitness comparable to wild-caught individuals. Importantly, we have eliminated the logistical complexities and costs of regularly feeding live larval fish to M. leidyi. Our updated protocols make it feasible to maintain continuous ctenophore cultures independent of access to both coastal populations of wild M. leidyi and larval fish culturing facilities.

Predicting cardiac frequencies in mammals

We develop a fluid mechanical model of the arterial tree in order to address the key question of what determines heart rate in mammals. We propose that the frequency of the pulsatile pressure gradient, which minimizes resistance to flow and facilitates fluid movement, coincides with the physiological heart rate. Using data from the literature on heart rate in 95 mammals as a function of body mass, and the radius of the aorta as a function of body mass, we construct a target curve of cardiac frequency versus aortic radius. This curve serves as a benchmark for comparison with our model's results. Our elastic one-dimensional model for pulsatile arterial flow, combined with experimental rheological data for human blood, enables us to calculate the frequency that minimizes flow resistance, which we express as a function of a characteristic vascular scale, in this case, the aorta radius. We find a reasonable agreement with the target curve, confirming a scaling law with the observed exponent for mammals ranging in size from ferrets to elephants. Our model provides a plausible explanation for the resting heart rate frequency in healthy mammals.

Population pharmacokinetics of brexpiprazole in Japanese healthy subjects and patients with schizophrenia

Brexpiprazole, widely approved for the treatment of schizophrenia, is an atypical antipsychotic that modulates serotonin-dopamine activity. To better understand the pharmacokinetics (PK) of brexpiprazole in Japanese patients, a population PK model was constructed and used to estimate steady state PK profiles and parameters as well as dopamine D2/D3 receptor occupancy profiles after repeated oral administrations of brexpiprazole at 1 and 2 mg/day. Nonlinear mixed effects modelling was used to analyse data from a total of 398 healthy subjects and patients with schizophrenia who received brexpiprazole in three Japanese clinical trials. The PK of brexpiprazole were well described by a two-compartment disposition model with transit absorption compartments. Estimated glomerular filtration rate, age and cytochrome P450 2D6 phenotype were identified as significant covariates on CL/F only. The model predicted that, at a dose of 2 mg/day, trough plasma concentration (90 % prediction interval) of brexpiprazole is 77.1 (22.4-173) ng/mL and that dopamine D2/D3 receptor occupancy is >80 % over one day for most patients at steady state. This suggests the recommended maintenance dose of 2 mg/day of brexpiprazole leads to clinically useful dopamine D2/D3 receptor occupancy at steady state in Japanese patients.

Dive Deep: Bioenergetic Adaptation of Deep-Sea Animals

The deep sea, which encompasses the largest habitat on Earth, presents a set of extreme and unique environmental conditions, including high hydrostatic pressure, near-freezing temperatures, and perpetual darkness. These conditions pose significant challenges to the survival and energy management of its inhabitants. Deep-sea organisms have evolved a range of bioenergetic adaptations to negotiate these harsh conditions, ensuring efficient energy acquisition and utilization. This review examines the multifaceted strategies employed by deep-sea animals, focusing on three key areas: energy input, digestive and absorptive efficiency, and energy consumption. We examine the physical environment of the deep sea, highlighting vertical profiles of temperature, salinity, and dissolved oxygen, which contrast sharply with surface conditions. Physiological adaptations of deep-sea species, such as specialized digestive systems and enzyme modifications that function optimally under high pressure, are explored in detail. Furthermore, we discuss behavioral adaptations, including diurnal vertical migration, which optimize energy intake and reduce metabolic costs. Comparative analyses with shallow-water species provide insights into the evolutionary pressures that have shaped these adaptations. This review also addresses the concept of "power budgeting", in which energy expenditures for specific dynamic actions (SDAs) must be balanced with other metabolic demands. This comprehensive examination of bioenergetic adaptation in deep-sea organisms enhances our understanding of their resilience and adaptability, offering glimpses into the complex interplay between environmental constraints and biological processes in one of the most challenging habitats on the planet.

A new computational framework for simulating airway resistance, fraction of exhaled nitric oxide, and diffusing capacity for nitric oxide

In this paper, we present a new computational framework for the simulation of airway resistance, the fraction of exhaled nitric oxide, and the diffusion capacity for nitric oxide in healthy and unhealthy lungs. Our approach is firstly based on a realistic representation of the geometry of healthy lungs as a function of body mass, which compares well with data from the literature, particularly in terms of lung volume and alveolar surface area. The original way in which this geometry is created, including an individual definition of the airways in the first seven generations of the lungs, makes it possible to consider the heterogeneous nature of the lungs in terms of perfusion and ventilation. In addition, a geometry can be easily modified to simulate various abnormalities, local or global (constriction, inflammation, perfusion defect). The natural variability of the lungs at constant body mass is also considered. The computational framework includes the possibility to simulate, on a given (possibly modified) geometry, a test to measure the flow resistance of the lungs (including its component due to the not fully developed flow in the first generations of lungs), a test to measure the concentration of nitric oxide in the exhaled air, and a test to measure the diffusion capacity for nitric oxide. This is implemented in the framework by solving different transport equations (momentum and convection/diffusion) describing these tests. Through numerous simulations, we demonstrate the ability of our model to reproduce results from the literature, both for healthy lungs and lungs of patients with asthma or chronic obstructive pulmonary disease. Such a computational framework, through the possibilities of numerous and rapid tests that it allows, sheds new light on experimental data by providing information on the phenomena that take place in the distal generations of the lungs, which are difficult to access with imaging.

Life sets off a cascade of machines

Life is invasive, occupying all physically accessible scales, stretching between almost nothing (protons, electrons, and photons) and almost everything (the whole biosphere). Motivated by seventeenth-century insights into this infinity, this paper proposes a language to discuss life as an infinite double cascade of machines making machines. Using this simplified language, we first discuss the micro-cascade proposed by Leibniz, which describes how the self-reproducing machine of the cell is built of smaller submachines down to the atomic scale. In the other direction, we propose that a macro-cascade builds from cells larger, organizational machines, up to the scale of the biosphere. The two cascades meet at the critical point of 103 s in time and 1 micron in length, the scales of a microbial cell. We speculate on how this double cascade evolved once a self-replicating machine emerged in the salty water of prebiotic earth.

The use of population pharmacokinetics to extrapolate food effects from human adults and beagle dogs to the pediatric population illustrated with ibuprofen as a case

Oral drug administration is the most convenient route of administration in the pediatric population. However, children are often not fasted when drugs are orally administered, hence potential food-drug interactions might occur. Most of these interactions are extrapolated from studies performed in human adults where a recommended high-fat, high-calorie meal is administered prior to drug dosing. As the recommended protocols are based on studies in support of adult drug development, these studies do not mimic the meal composition administered to the pediatric population, especially the very young ones, which renders food-drug interactions in this population understudied. Therefore, it was evaluated to what extent population pharmacokinetics could reliably extrapolate food effects from human adults and beagle dogs to mimic the real-life situation in the pediatric population. Eight human adults and six beagle dogs received ibuprofen under different dosing conditions (fasted, reference meal fed condition, infant formula fed condition). Population pharmacokinetic analysis was performed to derive the pharmacokinetic parameters to be scaled to pediatric ages. For both species, a one-compartment model best described the data, where in human adults a dual-input function to capture the double absorption peak significantly improved the model fit. Simulations for a virtual pediatric population demonstrated that the predictive ability of human adults and beagle dogs to inform absorption effects under different dosing conditions using population pharmacokinetic modeling appeared to be reasonable. However, to be able to fully validate the predictability of both species for ibuprofen, additional studies in the pediatric population are required to generate more informative data.

Would Phrynops geoffroanus' plastron formula and morphological diversity be preserved under anthropic conditions?

Phrynops geoffroanus has a wide distribution in South America, living in aquatic environments such as rivers, streams, and lakes, in natural and urban environments. In this work, the plastron formula and the diversity index associated with the allometric condition are established for the species. For the morphometric analyses, the following were calculated: standard error, class intervals, sample standard deviation, principal component analysis, and allometry. When evaluating the morphometric dependence, r = 0.85 was obtained, which allowed us to verify the allometric classification Y, the growth rate K, and the proportion of growth b for each segment that composes the length of the plastron (LP). Thus, the calculated morphometric set demonstrates that the plastron formula can serve as a diagnostic character for Phrynops geoffroanus. We inferred from this study that the plastron formula can be maintained even in conditions of high environmental degradation.

Impact of developmental temperature on neural growth, connectivity, and function

Environmental temperature dictates the developmental pace of poikilothermic animals. In Drosophila, slower development at lower temperatures results in higher brain connectivity, but the generality of such scaling across temperatures and brain regions and its impact on function are unclear. Here, we show that brain connectivity scales continuously across temperatures, in agreement with a first-principle model that postulates different metabolic constraints for the growth of the brain and the organism. The model predicts brain wiring under temperature cycles and the nonuniform temporal scaling of neural development across temperatures. Developmental temperature has notable effects on odor-driven behavior. Dissecting the circuit architecture and function of neurons in the olfactory pathway, we demonstrate that developmental temperature does not alter odor encoding in first- and second-order neurons, but it shifts the specificity of connections onto third-order neurons that mediate innate behaviors. We conclude that while some circuit computations are robust to the effects of developmental temperature on wiring, others exhibit phenotypic plasticity with possible adaptive advantages.

Impact of inter-city interactions on disease scaling

Inter-city interactions are critical for the transmission of infectious diseases, yet their effects on the scaling of disease cases remain largely underexplored. Here, we use the commuting network as a proxy for inter-city interactions, integrating it with a general scaling framework to describe the incidence of seven infectious diseases across Brazilian cities as a function of population size and the number of commuters. Our models significantly outperform traditional urban scaling approaches, revealing that the relationship between disease cases and a combination of population and commuters varies across diseases and is influenced by both factors. Although most cities exhibit a less-than-proportional increase in disease cases with changes in population and commuters, more-than-proportional responses are also observed across all diseases. Notably, in some small and isolated cities, proportional rises in population and commuters correlate with a reduction in disease cases. These findings suggest that such towns may experience improved health outcomes and socioeconomic conditions as they grow and become more connected. However, as growth and connectivity continue, these gains diminish, eventually giving way to challenges typical of larger urban areas - such as socioeconomic inequality and overcrowding - that facilitate the spread of infectious diseases. Our study underscores the interconnected roles of population size and commuter dynamics in disease incidence while highlighting that changes in population size exert a greater influence on disease cases than variations in the number of commuters.

A Pooled Pharmacokinetic Analysis for Piperacillin/Tazobactam Across Different Patient Populations: From Premature Infants to the Elderly

BACKGROUND AND OBJECTIVES

The pharmacokinetics (PK) of piperacillin/tazobactam (PIP/TAZ) is highly variable across different patient populations and there are controversies regarding non-linear elimination as well as the fraction unbound of PIP (fUNB_PIP). This has led to a plethora of subgroup-specific models, increasing the risk of misusing published models when optimising dosing regimens. In this study, we aimed to develop a single model to simultaneously describe the PK of PIP/TAZ in diverse patient populations and evaluate the current dosing recommendations by predicting the PK/pharmacodynamics (PD) target attainment throughout life.

METHODS

Population PK models were separately built for PIP and TAZ based on data from 13 studies in various patient populations. In the development of those single-drug models, postnatal age (PNA), postmenstrual age (PMA), total body weight (TBW), height, and serum creatinine (SCR) were tested as covariates. Subsequently, a combined population PK model was established and the correlations between the PK of PIP and TAZ were tested. Monte Carlo simulations were performed based on the final combined model to evaluate the current dosing recommendations.

RESULTS

The final combined model for PIP/TAZ consisted of four compartments (two for each drug), with covariates including TBW, PMA, and SCR. For a 70-kg, 35-year-old patient with SCR of 0.83 mg L-1, the PIP values for V1, CL, V2 and Q2 were 10.4 L, 10.6 L h-1, 11.6 L and 15.2 L h-1, respectively, and the TAZ values were 10.5 L, 9.58 L h-1, 13.7 L and 16.8 L h-1, respectively. The CL for both drugs show maturation in early life, reaching 50% at 54.2 weeks PMA. With advancing age, CL of TAZ declines to 50% at 61.6 years PMA, whereas CL of PIP declines more slowly, reaching 50% at 89.1 years PMA. The fUNB_PIP was estimated as 64.5% and non-linear elimination was not supported by our data. The simulation results indicated considerable differences in PK/PD target attainment for different patient populations under current recommended dosing regimens.

CONCLUSIONS

We developed a combined population PK model for PIP/TAZ across a broad range of patients covering the extremes of patient characteristics. This model can be used as a robust a priori model for Bayesian forecasting to achieve individualised dosing. The simulations indicate that adjustments based on the allometric theory as well as maturation and decline of CL of PIP may help the current dosing recommendations to provide consistent target attainment across patient populations.

MetaRange.jl: A Dynamic and Metabolic Species Range Model for Plant Species

Process-based models for range dynamics are urgently needed due to increasing intensity of human-induced biodiversity change. Despite a few existing models that focus on demographic processes, their use remains limited compared to the widespread application of correlative approaches. This slow adoption is largely due to the challenges in calibrating biological parameters and the high computational demands for large-scale applications. Moreover, increasing the number of simulated processes (i.e., mechanistic complexity) may further exacerbate those reasons of delay. Therefore, balancing mechanistic complexity and computational effectiveness of process-based models is a key area for improvement. A promising research direction is to expand demographically explicit metapopulation models by integrating metabolic constraints. We translated and expanded a previously developed R metapopulation model to Julia language and published it as a Julia module. The model integrates species-specific parameters such as preferred environmental conditions, biomass and dispersal ability with demographic rates (e.g., reproductive and mortality rates) derived from local temperature and biomass via the metabolic theory of ecology. We provide a simple application example for the model in which we illustrate a typical use case by predicting the future occurrence of Orchis militaris in Bavaria under different climate change scenarios. Our results show that climate change reduces habitat suitability overall, but some regions like the Franconian Forest and the Alps see increased suitability and abundance, confirming their role as refugia. Simulating metapopulation dynamics reveals that local population dynamics and dispersal are crucial for accurate predictions. For instance, increasing dispersal distance reduces overall abundance loss but also lessens population growth in refugia. This highlights the importance of measuring traits like dispersal ability to improve climate change forecasts.

Asymptotic convergence for the dynamics of a Duffing-like oscillator under scaling analyses

The dynamics of the convergence for the stationary state considering a Duffing-like equation are investigated. The driven potential for these dynamics is supplied by a damped forced oscillator that has a piecewise linear function. Fixed points and their basins of attraction were identified and measured. We used entropy basin techniques to characterize the basins of attraction, where a changeover in its boundary basin entropy is observed concerning the boundary length. Additionally, we have a set of polar coordinates to describe the asymptotic convergence of the dynamics based on the range of the control parameter and initial conditions. The entire convergence to the stationary state was characterized by scaling laws.

Dabigatran pharmacokinetic-pharmacodynamic in sheep: Informing dose for anticoagulation during cardiopulmonary bypass

BACKGROUND

The effect of the anticoagulant, dabigatran, and its antagonist, idarucizumab, on coagulation remains poorly quantified. There are few pharmacokinetic-pharmacodynamic data available to determine dabigatran dose in humans or animals undergoing cardiopulmonary bypass.

METHODS

Five sheep were given intravenous dabigatran 4 mg/kg. Blood samples were collected for thromboelastometric reaction time (R-time) and drug assay at 5, 15, 30, 60, 120, 240, 480 min, and 24 h. Plasma dabigatran concentrations and R-times were analyzed using an integrated pharmacokinetic-pharmacodynamic model using non-linear mixed effects. The impact of idarucizumab 15 mg/kg administered 120 min after dabigatran 4 mg/kg and its effect on R-time was observed.

RESULTS

A 2-compartment model described dabigatran pharmacokinetics with a clearance (CL 0.0453 L/min/70 kg), intercompartment clearance (Q 0.268 L/min/70 kg), central volume of distribution (V1 2.94 L/70 kg), peripheral volume of distribution (V2 9.51 L/70 kg). The effect compartment model estimates for a sigmoid EMAX model using Reaction time had an effect site concentration (Ce50 64.2 mg/L) eliciting half of the maximal effect (EMAX 180 min). The plasma-effect compartment equilibration half time (T1/2keo) was 1.04 min. Idarucizumab 15 mg/kg reduced R-time by approximately 5 min.

CONCLUSIONS

Dabigatran reversibly binds to the active site on the thrombin molecule, preventing activation of coagulation factors. The pharmacologic target concentration strategy uses pharmacokinetic-pharmacodynamic information to inform dose. A loading dose of dabigatran 0.25 mg/kg followed by a maintenance infusion of dabigatran 0.0175 mg/kg/min for 30 min and a subsequent infusion dabigatran 0.0075 mg/kg/min achieves a steady state target concentration of 5 mg/L in a sheep model.

Scaling of shoot and root respiration of woody and herbaceous plants

Woody and herbaceous plants are the main components of global terrestrial ecosystems, and their growth, adaptation and survival depend largely on the metabolism of shoots and roots. Therefore, understanding size-scaling of metabolic rates in woody and herbaceous plants, and in shoots and roots, is a fundamental issue in ecology. However, few empirical studies have examined metabolic scaling exponents across a wide range of plant sizes. Using whole-plant chamber systems, we measured respiration rates of entire root systems and shoots of 96 woody species (n = 1243) and 33 herbaceous species (n = 463) from various terrestrial biomes, with plant masses spanning nine orders of magnitude. Scaling exponents for relationships between respiration rates and fresh mass were greater in shoots than in roots, and both were greater in herbaceous plants than in woody plants. Furthermore, scaling of whole-plant respiration, including various species, converged separately for woody and herbaceous plants. These findings suggest some general physico-chemical constraints on energy use by shoots and roots of individual plants in various terrestrial biomes, including forests and grasslands. These data will advance our understanding of terrestrial ecosystem structure and function.

On the causal connection in lifespan correlations and the possible existence of a 'number of life' at molecular level

Multiple physiological traits correlates with lifespan, being unclear both the causal connection among them and with the process of ageing. In this paper, we show that six traits (such as metabolic rate, mass, heart rate, etc) acting at the system level, are all related to lifespan thru the existence of an approximately constant number of respiration cycles in a lifespan ([Formula: see text]), therefore, we find that those relationships are not independently related to ageing. In addition, we study if the approximately constant [Formula: see text] is possibly linked with the end-of-lifespan somatic mutation burden, another number recently found to be approximately constant (Cagan, Nature 604:517-524, 2022). We find that the dataset of mammals studied is consistent with a direct proportionality between the somatic mutation rate and the respiration frequency, being a tentative link between both invariant numbers.

Allometric scaling of somatic mutation and epimutation rates in trees

How long-lived trees escape "mutational meltdown" despite centuries of continuous growth remains puzzling. Here we integrate recent studies to show that the yearly rate of somatic mutations and epimutations (μY) scales inversely with generation time (G), and follows the same allometric power law found in mammals (μY ∝ G-1). Deeper insights into the scaling function may permit predictions of somatic (epi)mutation rates from life-history traits without the need for genomic data.

Emerging cancer therapies: targeting physiological networks and cellular bioelectrical differences with non-thermal systemic electromagnetic fields in the human body - a comprehensive review

A steadily increasing number of publications support the concept of physiological networks, and how cellular bioelectrical properties drive cell proliferation and cell synchronization. All cells, especially cancer cells, are known to possess characteristic electrical properties critical for physiological behavior, with major differences between normal and cancer cell counterparts. This opportunity can be explored as a novel treatment modality in Oncology. Cancer cells exhibit autonomous oscillations, deviating from normal rhythms. In this context, a shift from a static view of cellular processes is required for a better understanding of the dynamic connections between cellular metabolism, gene expression, cell signaling and membrane polarization as states in constant flux in realistic human models. In oncology, radiofrequency electromagnetic fields have produced sustained responses and improved quality of life in cancer patients with minimal side effects. This review aims to show how non-thermal systemic radiofrequency electromagnetic fields leads to promising therapeutic responses at cellular and tissue levels in humans, supporting this newly emerging cancer treatment modality with early favorable clinical experience specifically in advanced cancer.

Beyond the mosaic model of brain evolution: Rearing environment defines local and global plasticity

Comparative animal studies have identified a trend toward a more global structural organization as brains become larger, suggesting that brain regions grow in sync as predicted by the concerted model of brain evolution. At the same time, brain plasticity studies have identified a boost in local brain structure triggered by the environment, suggesting that brain regions grow independently, as predicted by the mosaic model. Nevertheless, it is unclear whether the environment can also trigger shifts toward a more global brain structure, that is, whether phenotypic plasticity proceeds in a concerted fashion. Here, we examined the impact of radically different rearing environments on brain organization in a teleost fish, the three-spined stickleback (Gasterosteus aculeatus). We computed novel indices of local and global brain structure across groups reared in the two environments and entered them as predictors of differences in brain and body sizes. Changes in local brain structure predicted differences in both body and brain sizes, whereas changes in global brain structure only predicted differences in brain size. Our findings highlight the emergence of brain plasticity in a population as local and global changes that are both compatible with the concerted model.

Inferring the metabolic rate of bone

The bone organ is poorly represented in comparative research on mammalian mass-specific metabolic rates. As a first order attempt to remedy this, from the literature we collected mass-specific metabolic rates for all major organs except for the bone organ, and by subtraction infer the rate for the bone organ. The scaling relationships are given of each whole-organ mass-specific metabolic rate and of the relationship between whole-organ metabolic rate and body mass. Scaling of the lung, adipose depot and bone organ with body mass is higher than would be expected by ¾ power scaling. We interpret the similar scalings of bone and the adipose depot in light of their evolved regulation of whole-body metabolism. We also briefly examine the supra-¾ power scaling of the lung as well as the independence of the mass-specific metabolic rate of the heart from body mass. The bone organ exhibits relatively high energy expenditure with increasing body size. The bone marrow and its medullary adipocyte store may be responsible for engendering the greater share of the bone organ's energetic cost.

Scarpa Matuck B, Yang W, Qin L, Yan F, Lima JAC, Arbab-Zadeh A, Wolfe S. Prognostic Value of Coronary CT Angiography-Derived Quantitative Flow Ratio in Suspected Coronary Artery Disease

Background The prognostic value of coronary CT angiography (CTA)-derived quantitative flow ratio (CT-QFR) remains unknown. Purpose To determine the prognostic value of CT-QFR in predicting the long-term outcomes of patients with suspected coronary artery disease (CAD) in comparison with invasive coronary angiography (ICA)/SPECT and to determine the influence of prior percutaneous coronary intervention (PCI) on the prognostic value of CT-QFR. Materials and Methods In this secondary analysis of the prospective international CORE320 study, 379 participants who underwent coronary CTA and SPECT within 60 days before ICA between November 2009 and July 2011 were included for follow-up. The coronary CTA images were analyzed to determine CT-QFR. The primary outcome was major adverse cardiovascular events (MACEs) in the 5-year follow-up. Kaplan-Meier curves, multivariable Cox regression models adjusted for clinical variables, and areas under the receiver operating characteristic curves (AUCs) were used to assess and compare the predictive ability of CT-QFR and ICA/SPECT. Results CT-QFR computation and 5-year follow-up data were available for 310 participants (median age, 62 years), of whom 205 (66%) were male. CT-QFR (hazard ratio, 1.9 [95% CI: 1.0, 3.5]; P = .04) and prior myocardial infarction (hazard ratio, 2.5 [95% CI: 1.5, 4.0]; P < .001) were independent predictors of MACE occurrence in the 5-year follow-up. MACE-free survival rates were similar in participants with normal CT-QFR and ICA/SPECT (82% vs 80%; P = .45) and in participants with abnormal CT-QFR and ICA/SPECT findings (60% vs 57%; P = .40). In participants with prior PCI, CT-QFR had a lower AUC in predicting MACEs than in participants without prior PCI (0.44 vs 0.70; P < .001). Conclusion CT-QFR was an independent predictor of MACEs in the 5-year follow-up in participants with suspected CAD and showed similar 5-year prognostic value to ICA/SPECT; however, prior PCI affected CT-QFR ability to predict MACEs. Clinical trial registration no. NCT00934037 © RSNA, 2024 Supplemental material is available for this article.

Whether hypoxia tolerance improved after short-term fasting is closely related to phylogeny but not to foraging mode in freshwater fish species

The combined stresses of fasting and hypoxia are common events during the life history of freshwater fish species. Hypoxia tolerance is vital for survival in aquatic environments, which requires organisms to down-regulate their maintenance energetic expenditure while simultaneously preserving physiological features such as oxygen supply capacity under conditions of food deprivation. Generally, infrequent-feeding species who commonly experience food shortages might evolve more adaptive strategies to cope with food deprivation than frequent-feeding species. Thus, the present study aimed to test whether the response of hypoxia tolerance in fish to short-term fasting (2 weeks) varied with different foraging modes. Fasting resulted in similar decreases in maintenance energetic expenditure and similar decreases in Pcrit and Ploe between fishes with different foraging modes, whereas it resulted in decreased oxygen supply capacity only in frequent-feeding fishes. Furthermore, independent of foraging mode, fasting decreased Pcrit and Ploe in all Cypriniformes and Siluriformes species but not in Perciformes species. The mechanism for decreased Pcrit and Ploe in Cypriniformes and Siluriformes species is at least partially due to the downregulated metabolic demand and/or the maintenance of a high oxygen supply capacity while fasting. The present study found that the effect of fasting on hypoxia tolerance depends upon phylogeny in freshwater fish species. The information acquired in the present study is highly valuable in aquaculture industries and can be used for species conservation in the field.

A Population Pharmacokinetic Study to Evaluate Doxorubicin Exposure Across All Age Groups

BACKGROUND

The effect of age on doxorubicin pharmacokinetics remains inconclusive, especially in patients at the extremes of the age spectrum. We developed a population pharmacokinetic model to further investigate the impact of age on the pharmacokinetics of doxorubicin.

METHODS

A three-compartment model, incorporating allometric scaling was developed to describe doxorubicin pharmacokinetics across all ages. First, the effect of age in young patients was investigated, by adding a maturation function on clearance (CL), the central compartment (V1) and peripheral compartments (V2 and V3). Second, the impact of ageing was investigated by adding a maximal effect (Emax) function on CL, V1, V2, and V3. To investigate the overall impact of age on doxorubicin exposure, various simulations were conducted.

RESULTS

A total of 168 patients (age: 0.11-90 years) with 555 doxorubicin samples were included. The maturation function was relevant for V1 and V2 (13.1 and 23.7 L, respectively), leading to an increase in V1 and V2 with increasing age. In contrast, adding an Emax function only impacted V3 (1063L), resulting in a decrease of V3 with age. Simulations showed no clinically relevant difference in the exposure of doxorubicin between age groups.

CONCLUSION

A population pharmacokinetic model with data across the age range showed that age predominantly affected volumes of distribution of the central and peripheral compartments. These effects were not considered to be clinically relevant based on performed simulations. This supports the use of currently used doxorubicin dosages of 1 mg/kg for infants and toddlers < 10 kg and body surface area-based dosing for other patients.

The second law of thermodynamics, life and Earth's planetary machinery revisited

Life is a planetary feature that depends on its environment, but it has also strongly shaped the physical conditions on Earth, having created conditions highly suitable for a productive biosphere. Clearly, the second law of thermodynamics must apply to these dynamics as well, but how? What insights can we gain by placing life and its effects on planetary functioning in the context of the second law? In Kleidon (2010), I described a thermodynamic Earth system perspective by placing the functioning of the Earth system in terms of the second law. The Earth system is represented by a planetary hierarchy of energy transformations that are driven predominantly by incoming solar radiation, these transformations are constrained by the second law, but they are also modified by the feedbacks from various dissipative activities. It was then hypothesised that life evolves its dissipative activity to the limits imposed by this hierarchy and evolves feedbacks aimed at pushing these limits to higher levels of dissipative activity. Here I provide an update of this perspective. I first review applications to climate and global climate change to demonstrate its success in predicting magnitudes of physical processes, particularly regarding temperatures, heat redistribution and hydrological cycling. I then focus on the limits to dissipative activity of the biosphere. It would seem that the limitations by thermodynamics act indirectly by imposing limitations associated with transport and material exchange. I substantiate this interpretation and discuss the broader implications for habitability, the emergence and evolution of life, and the contemporary biosphere.

Scale invariance in early embryonic development

The expression of a few key genes determines the body plan of the fruit fly. We show that the spatial expression patterns for several of these genes scale precisely with embryo size. Discrete positional markers such as the peaks in striped patterns or the boundaries of expression domains have positions along the embryo's major axis proportional to embryo length, accurate to within 1%. Further, the information (in bits) that graded patterns of expression provide about a cell's position can be decomposed into information about fractional or scaled position and information about absolute position or embryo length; all information available is about scaled position, with [Formula: see text]2% error. These findings imply that the underlying genetic network's behavior exhibits scale invariance in a more precise mathematical sense. We argue that models that can explain this scale invariance also have a "zero mode" in the dynamics of gene expression, and this connects to observations on the spatial correlation of fluctuations in expression levels.

A scaling law for predicting urban trees canopy cooling efficiency

Urban heat mitigation is a pressing concern for cities. Intense urban heat poses a threat to human health and urban sustainability. Tree planting is one of the most widely employed nature-based heat mitigation methods worldwide. Therefore, city policy makers require knowledge of how much temperature will be reduced by increasing urban tree canopy (UTC). Cooling efficiency (CE), which was been proposed to quantify the magnitude of temperature reduction associated with a 1% increase in UTC, has been primarily investigated at smaller scales previously. However, such small-scale results cannot be used to develop policy at the whole-city scale. This study developed a method that reveals the scaling relations of CE so as to predict its effects at the city scale. CE was found to follow the form of a power law as spatial scale increased from the small analytical units through intermediate size units up to the extent of a whole city. The power law form appeared consistently across cities with different climate backgrounds during summer daylight hours. Furthermore, the power law form was robust within cities under different summer weather conditions. The power-law scaling approach can thus be used to predict CE at the whole-city scale, providing a useful tool for managers to set UTC goals to mitigate extreme urban heat.

Genotype × environment × management analysis to define allometric rules between leaves and stems in wheat

Allometric rules provide insights into structure-function relationships across species and scales and are commonly used in ecology. The fields of agronomy, plant phenotyping, and modeling also need simplifications such as those provided by allometric rules to reconcile data at different temporal and spatial levels (organs/canopy). This study explores the variations in relationships for wheat in terms of the distribution of crop green area between leaves and stems, and the allocation of above-ground biomass between leaves and stems during the vegetative period, using a large dataset covering different years, countries, genotypes, and management practices. The results showed that the relationship between leaf and stem area was linear, genotype-specific, and sensitive to radiation. The relationship between leaf and stem biomass depended on genotype and nitrogen fertilization. The mass per area, associating area and biomass for both leaf and stem, varied strongly by developmental stage and was significantly affected by environment and genotype. These allometric rules were evaluated and shown to have satisfactory performance, and their potential use is discussed with regard to current phenotyping techniques and plant/crop models. Our results enable the definition of models and minimum datasets required for characterizing diversity panels and making predictions in various genotype × environment × management contexts.