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"Allometric scaling"

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https://www.readbyqxmd.com/read/28099761/size-structuring-and-allometric-scaling-relationships-in-coral-reef-fishes
#1
Jillian C Dunic, Julia K Baum
Temperate marine fish communities are often size structured, with predators consuming increasingly larger prey and feeding at higher trophic levels as they grow. Gape limitation and ontogenetic diet shifts are key mechanisms by which size structuring arises in these communities. Little is known, however, about size structuring in coral reef fishes. Here, we aimed to advance understanding of size structuring in coral reef food webs by examining the evidence for these mechanisms in two groups of reef predators...
January 18, 2017: Journal of Animal Ecology
https://www.readbyqxmd.com/read/28018224/prediction-of-deoxypodophyllotoxin-disposition-in-mouse-rat-monkey-and-dog-by-physiologically-based-pharmacokinetic-model-and-the-extrapolation-to-human
#2
Yang Chen, Kaijing Zhao, Fei Liu, Qiushi Xie, Zeyu Zhong, Mingxing Miao, Xiaodong Liu, Li Liu
Deoxypodophyllotoxin (DPT) is a potential anti-tumor candidate prior to its clinical phase. The aim of the study was to develop a physiologically based pharmacokinetic (PBPK) model consisting of 13 tissue compartments to predict DPT disposition in mouse, rat, monkey, and dog based on in vitro and in silico inputs. Since large interspecies difference was found in unbound fraction of DPT in plasma, we assumed that Kt:pl,u (unbound tissue-to-plasma concentration ratio) was identical across species. The predictions of our model were then validated by in vivo data of corresponding preclinical species, along with visual predictive checks...
2016: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/28000286/population-pharmacokinetics-of-temsirolimus-and-sirolimus-in-children-with-recurrent-solid-tumours-a-report-from-the-children-s-oncology-group
#3
Tomoyuki Mizuno, Tsuyoshi Fukuda, Uwe Christians, John P Perentesis, Maryam Fouladi, Alexander A Vinks
AIMS: Temsirolimus is an inhibitor of the mammalian target of rapamycin (mTOR). Pharmacokinetic (PK) characterization of temsirolimus in children is limited and there is no paediatric temsirolimus population PK model available. The objective of this study was to simultaneously characterize the PK of temsirolimus and its metabolite sirolimus in paediatric patients with recurrent solid or central nervous system tumours and to develop a population PK model. METHODS: The PK data for temsirolimus and sirolimus were collected as a part of a Children's Oncology Group phase I clinical trial in paediatric patients with recurrent solid tumours...
November 7, 2016: British Journal of Clinical Pharmacology
https://www.readbyqxmd.com/read/27999040/population-pharmacokinetics-of-cefazolin-before-during-and-after-cardiopulmonary-bypass-to-optimize-dosing-regimens-for-children-undergoing-cardiac-surgery
#4
Pieter A J G De Cock, Hussain Mulla, Sarah Desmet, Filip De Somer, Brett C McWhinney, Jacobus P J Ungerer, Annelies Moerman, Sabrina Commeyne, Johan Vande Walle, Katrien Francois, Johan G C Van Hasselt, Peter De Paepe
OBJECTIVES: The objective of this study was to characterize cefazolin serum pharmacokinetics in children before, during and after cardiopulmonary bypass (CPB), in order to derive an evidence-based dosing regimen. PATIENTS AND METHODS: This study included children who received cefazolin before surgical incision, before cessation of CPB and after surgery. Blood samples of total and unbound cefazolin concentrations were collected before, during and after CPB. The cefazolin concentration-time profiles were analysed using population pharmacokinetic modelling and predictors for interindividual variability in pharmacokinetic parameters were investigated...
December 20, 2016: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/27943381/body-mass-normalization-for-ultrasound-measurements-of-adolescent-lateral-abdominal-muscle-thickness
#5
Pawel Linek, Edward Saulicz, Tomasz Wolny, Andrzej Myśliwiec
OBJECTIVES: The purpose of this study was to determine the value of the allometric parameter for ultrasound measurements of the thickness of the oblique external (OE), internal (OI), and transversus abdominis (TrA) muscles in the adolescent population. The allometric parameter is the slope of the linear regression line between the log transformed body mass and log transformed muscle size measurement. METHODS: The study included 321 adolescents between the ages of 10 and 17, consisting of 160 boys and 161 girls...
December 10, 2016: Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine
https://www.readbyqxmd.com/read/27943220/population-pharmacokinetics-and-exploratory-pharmacodynamics-of-lorazepam-in-pediatric-status-epilepticus
#6
Daniel Gonzalez, James M Chamberlain, Jeffrey T Guptill, Michael Cohen-Wolkowiez, Barrie Harper, Jian Zhao, Edmund V Capparelli
BACKGROUND: Lorazepam is one of the preferred agents used for intravenous treatment of status epilepticus (SE). We combined data from two pediatric clinical trials to characterize the population pharmacokinetics of intravenous lorazepam in infants and children aged 3 months to 17 years with active SE or a history of SE. METHODS: We developed a population pharmacokinetic model for lorazepam using the NONMEM software. We then assessed exploratory exposure-response relationships using the overall efficacy and safety study endpoints, and performed dosing simulations...
December 9, 2016: Clinical Pharmacokinetics
https://www.readbyqxmd.com/read/27935030/temperature-effects-on-mass-scaling-exponents-in-colonial-animals-a-manipulative-test
#7
Diego R Barneche, Craig R White, Dustin J Marshall
Body size and temperature are fundamental drivers of ecological processes because they determine metabolic rates at the individual level. Whether these drivers act independently on individual-level metabolic rates remains uncertain. Most studies of intraspecific scaling of unitary organisms must rely on preexisting differences in size to examine its relationship with metabolic rate, thereby potentially confounding size-correlated traits (e.g., age, nutrition) with size, which can affect metabolic rate. Here, we use a size manipulation approach to test whether metabolic mass scaling and temperature dependence interact in four species (two phyla) of colonial marine invertebrates...
October 15, 2016: Ecology
https://www.readbyqxmd.com/read/27903219/prediction-of-plasma-concentration-time-profiles-of-drugs-in-humans-from-animals-following-oral-administration-an-allometric-approach
#8
Iftekhar Mahmood
BACKGROUND: Allometric scaling is regularly used for the prediction of human pharmacokinetic (PK) parameters from animal PK studies. The predicted human PK parameters can also be used for the prediction of plasma concentration-time profiles in humans. OBJECTIVES: The main objective of this work is to predict human concentration-time profiles of drugs (one-compartment model) following oral administration using animal oral pharmacokinetic parameters. METHODS: Six drugs from the literature were chosen that were described by one-compartment model in both humans and animals following oral administration...
November 21, 2016: Current Drug Metabolism
https://www.readbyqxmd.com/read/27902691/do-vascular-networks-branch-optimally-or-randomly-across-spatial-scales
#9
Elif Tekin, David Hunt, Mitchell G Newberry, Van M Savage
Modern models that derive allometric relationships between metabolic rate and body mass are based on the architectural design of the cardiovascular system and presume sibling vessels are symmetric in terms of radius, length, flow rate, and pressure. Here, we study the cardiovascular structure of the human head and torso and of a mouse lung based on three-dimensional images processed via our software Angicart. In contrast to modern allometric theories, we find systematic patterns of asymmetry in vascular branching, potentially explaining previously documented mismatches between predictions (power-law or concave curvature) and observed empirical data (convex curvature) for the allometric scaling of metabolic rate...
November 2016: PLoS Computational Biology
https://www.readbyqxmd.com/read/27892765/comparison-of-predictability-for-human-pharmacokinetics-parameters-among-monkeys-rats-and-chimeric-mice-with-humanised-liver
#10
Maki Miyamoto, Shinji Iwasaki, Ikumi Chisaki, Sayaka Nakagawa, Nobuyuki Amano, Hideki Hirabayashi
The aim of the present study was to evaluate the usefulness of chimeric mice with humanised liver (PXB mice) for the prediction of clearance (CLt) and volume of distribution at steady state (Vdss), in comparison with monkeys, which have been reported as a reliable model for human pharmacokinetics (PK) prediction, and with rats, as a conventional PK model. CLt and Vdss values in PXB mice, monkeys, and rats were determined following intravenous administration of 30 compounds known to be mainly eliminated in humans via the hepatic metabolism by various drug-metabolising enzymes...
November 28, 2016: Xenobiotica; the Fate of Foreign Compounds in Biological Systems
https://www.readbyqxmd.com/read/27828977/dinosaur-metabolism-and-the-allometry-of-maximum-growth-rate
#11
Nathan P Myhrvold
The allometry of maximum somatic growth rate has been used in prior studies to classify the metabolic state of both extant vertebrates and dinosaurs. The most recent such studies are reviewed, and their data is reanalyzed. The results of allometric regressions on growth rate are shown to depend on the choice of independent variable; the typical choice used in prior studies introduces a geometric shear transformation that exaggerates the statistical power of the regressions. The maximum growth rates of extant groups are found to have a great deal of overlap, including between groups with endothermic and ectothermic metabolism...
2016: PloS One
https://www.readbyqxmd.com/read/27799204/population-pharmacokinetic-modeling-to-estimate-the-contributions-of-genetic-and-nongenetic-factors-to-efavirenz-disposition
#12
Jason D Robarge, Ingrid F Metzger, Jessica Lu, Nancy Thong, Todd C Skaar, Zeruesenay Desta, Robert R Bies
Efavirenz pharmacokinetics is characterized by large between-subject variability, which determines both therapeutic response and adverse effects. Some of the variability in efavirenz pharmacokinetics has been attributed to genetic variability in cytochrome P450 genes that alter efavirenz metabolism, such as CYP2B6 and CYP2A6 While the effects of additional patient factors have been studied, such as sex, weight, and body mass index, the extent to which they contribute to variability in efavirenz exposure is inconsistently reported...
January 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/27771399/noninvasive-ct-derived-ffr-based-on%C3%A2-structural-and%C3%A2-fluid-analysis-a-comparison-with-invasive-ffr-for-detection-of-functionally-significant-stenosis
#13
Brian S Ko, James D Cameron, Ravi K Munnur, Dennis T L Wong, Yasuko Fujisawa, Takuya Sakaguchi, Kenji Hirohata, Jacqui Hislop-Jambrich, Shinichiro Fujimoto, Kazuhisa Takamura, Marcus Crossett, Michael Leung, Ahilan Kuganesan, Yuvaraj Malaiapan, Arthur Nasis, John Troupis, Ian T Meredith, Sujith K Seneviratne
OBJECTIVES: This study describes the feasibility and accuracy of a novel computed tomography (CT) fractional flow reserve (FFR) technique based on alternative boundary conditions. BACKGROUND: Techniques used to compute FFR based on images acquired from coronary computed tomography angiography (CTA) are described. Boundary conditions were typically determined by allometric scaling laws and assumptions regarding microvascular resistance. Alternatively, boundary conditions can be derived from the structural deformation of coronary lumen and aorta, although its accuracy remains unknown...
October 14, 2016: JACC. Cardiovascular Imaging
https://www.readbyqxmd.com/read/27763679/theory-based-pkpd-of-s-and-r-warfarin-and-effects-on-inr-influence-of-body-size-composition-and-genotype-in-cardiac-surgery-patients
#14
Ling Xue, Nick Holford, Xiao-Liang Ding, Zhen-Ya Shen, Chen-Rong Huang, Hua Zhang, Jing-Jing Zhang, Zhe-Ning Guo, Cheng Xie, Ling Zhou, Zhi-Yao Chen, Lin-Sheng Liu, Li-Yan Miao
AIMS: The aims of this study are to apply a theory based mechanistic model to describe the pharmacokinetics (PK) and pharmacodynamics (PD) of S- and R-warfarin. METHODS: Clinical data were obtained from 264 patients. Total concentrations for S- and R-warfarin were measured by ultra-high performance liquid tandem mass spectrometry. Genotypes were measured using pyrosequencing. A sequential population pharmacokinetic parameter with data method was used to describe the international normalized ratio (INR) time course...
October 20, 2016: British Journal of Clinical Pharmacology
https://www.readbyqxmd.com/read/27741055/reference-curves-for-field-tests-of-musculoskeletal-fitness-in-u-s-children-and-adolescents-the-2012-nhanes-national-youth-fitness-survey
#15
Kelly R Laurson, Pedro F Saint-Maurice, Gregory J Welk, Joey C Eisenmann
The purpose of the study was to describe current levels of musculoskeletal fitness (MSF) in U.S. youth by creating nationally representative age- and sex-specific growth curves for handgrip strength (including relative and allometrically scaled handgrip), modified pull-ups, and the plank test. Participants in the National Youth Fitness Survey (n = 1453) were tested on MSF, aerobic capacity (via submaximal treadmill test), and body composition (body mass index [BMI], waist circumference, and skinfolds). Using LMS regression, age- and sex-specific smoothed percentile curves of MSF were created and existing percentiles were used to assign age- and sex-specific z-scores for aerobic capacity and body composition...
October 6, 2016: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27705784/hierarchical-size-scaling-during-multicellular-growth-and-development
#16
Sravanti Uppaluri, Stephanie C Weber, Clifford P Brangwynne
Multicellular organisms must regulate their growth across the diverse length scales of biological organization, but how this growth is controlled from organelle to body, while coordinating interdependent functions at each scale, remains poorly understood. We utilized the C. elegans worm intestine as a model system to identify distinct allometric scaling laws, revealing that the growth of individual structures is differentially regulated during development. We show that the volume of the nucleolus, a subcellular organelle, is directly proportional (isometric) to cell size during larval development...
October 4, 2016: Cell Reports
https://www.readbyqxmd.com/read/27704554/prediction-of-clearance-in-neonates-and-infants-%C3%A2-3-months-of-age-for-drugs-that-are-glucuronidated-a-comparative-study-between-allometric-scaling-and-physiologically-based-pharmacokinetic-modeling
#17
Iftekhar Mahmood, Tasneem Ahmad, Najia Mansoor, S M Sharib
The objective of this study was to evaluate the predictive performances of allometric models and a physiologically based pharmacokinetic model (PBPK) to predict clearance of glucuronidated drugs in neonates (≤ 3 months of age). From the literature, clearance values for 9 drugs (glucuronidated) for neonates and adults were obtained. Three allometric models were used to predict clearances of these glucuronidated drugs. A PBPK model was developed using the physicochemical, biopharmaceutical, and metabolic properties together with known pediatric physiology and enzymatic ontogeny...
October 4, 2016: Journal of Clinical Pharmacology
https://www.readbyqxmd.com/read/27686596/allometric-scaling-of-electrical-excitation-and-propagation-in-the-mammalian-heart
#18
Guillaume Bassil, Manuel Zarzoso, Sami F Noujaim
Variations in body mass impose constraints on the structure and function of mammalian species, including those of the cardiovascular system. Numerous biological processes, including cardiovascular parameters, have been shown to scale with body mass (BM) according to the law of allometric scaling: Y = Y =a∙BM(b) (Y, biological process; a, normalization constant; b, scaling exponent, which in many instances is a multiple of ¼). These parameters include heart and breathing rates, intervals and subintervals of the electrocardiogram (ECG), action potential duration (APD), metabolic rate, and temporal properties of ventricular fibrillation...
September 26, 2016: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/27669442/arterial-stiffness-is-reduced-regardless-of-resistance-training-load-in-young-men
#19
Jason S Au, Sara Y Oikawa, Robert W Morton, Maureen J MacDonald, Stuart M Phillips
PURPOSE: Discrepancies regarding the impact of resistance exercise training (RET) on arterial stiffness have led to uncertainty regarding the impact of RET on cardiovascular health. Confounding our understanding in this area are the roles of: load (heavier vs lighter), participant cardiovascular health, and the method of arterial stiffness assessment. We aimed to investigate the effects of a heavier versus a lighter load resistance training protocol on both central and local arterial stiffness in previously-trained young men...
September 23, 2016: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/27667689/right-ventricular-involvement-in-feline-hypertrophic-cardiomyopathy
#20
K E Schober, S I Savino, V Yildiz
OBJECTIVES: To evaluate right ventricular (RV) wall thickness and chamber dimensions in cats with hypertrophic cardiomyopathy (HCM). ANIMALS: One hundred fifty-one healthy control cats and 200 cats with HCM. METHODS: Retrospective, observational, clinical cohort study. Two-dimensional echocardiograms from all cats were analyzed. Right atrial diameter, RV free wall thickness, and RV chamber diameter were quantified using multiple imaging views...
December 2016: Journal of Veterinary Cardiology: the Official Journal of the European Society of Veterinary Cardiology
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