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"Allometric scaling"

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
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
Iftekhar Mahmod, 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
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
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
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...
September 22, 2016: Journal of Veterinary Cardiology: the Official Journal of the European Society of Veterinary Cardiology
Tao Liu, Parima Ghafoori, Jogarao V S Gobburu
Pharmacokinetics (PK) plays a key role in bridging drug efficacy and safety from adults to pediatrics. The principal purpose of projecting dosing in pediatrics is to guide trial design, not to waive the study per se. This research was designed to evaluate whether the allometric scaling (AS) approach is a satisfactory method to design PK study in pediatric patients 2 years and older. We systematically evaluated drugs that had pediatrics label information updated from 1998 to 2015. Only intravenous (IV) or oral administration drugs with available PK information in both pediatrics and adults from FDA approved labels were included...
September 21, 2016: Journal of Clinical Pharmacology
Wan-Su Park, Seunghoon Han, Jongtae Lee, Taegon Hong, Jonghwa Won, Yangmi Lim, Kyuhyun Lee, Han Yeul Byun, Dong-Seok Yim
GC1118 is an anti-epidermal growth factor receptor (EGFR) monoclonal antibody that is currently under clinical development. In this study, the pharmacokinetics (PK) of GC1118 were modelled in monkeys to predict human PK and receptor occupancy (RO) profiles. The serum concentrations of GC1118 and its comparator (cetuximab) were assessed in monkeys with a non-compartmental analysis and a target-mediated drug disposition (TMDD) model following intravenous infusion (3-25 mg/kg) of these drugs. The scaling exponent of the EGFR synthesis rate was determined using a sensitivity analysis...
September 16, 2016: Basic & Clinical Pharmacology & Toxicology
Hugo Maciejewski, Abderrahmane Rahmani, Frédéric Chorin, Julien Lardy, Caroline Giroux, Sébastien Ratel
PURPOSE: The aim of the present study was to determine whether the anaerobic performance assessed by a modified Wingate test could account for the 1,500-m rowing ergometer performance in young competitive rowers. METHODS: Fourteen national-level adolescent rowers performed on a rowing ergometer i) a 30-s all-out exercise (i.e., modified Wingate test) and ii) a 1,500-m all-out exercise (i.e., rowing performance). For each of these two exercises, the mean power output was considered as the main performance criterion (PWIN and P1500, respectively)...
August 19, 2016: Pediatric Exercise Science
Norbert Kunert
Daily xylem sap flux values (daily Js) and maximum xylem sap flux values (max Js) from 125 tropical trees from different study sites in the Neotropics were compared. A cross species and study site relationship was found between daily and maximum values. The relationship can be expressed as daily Js=6.5x max Js. The geometrical relationship between the maximum xylem sap flux of a given day is thus defining the daily xylem sap flux rates. Assuming a bell-shaped diurnal sap flux course and a relatively constant day length the maximum xylem sap flux is the only possible changing variable to define daily fluxes...
September 2, 2016: Journal of Plant Physiology
Vasudev Kantae, Elke H J Krekels, Anita Ordas, Oskar González, Rob C van Wijk, Amy C Harms, Peter I Racz, Piet H van der Graaf, Herman P Spaink, Thomas Hankemeier
Zebrafish larvae (Danio rerio) are increasingly used to translate findings regarding drug efficacy and safety from in vitro-based assays to vertebrate species, including humans. However, the limited understanding of drug exposure in this species hampers its implementation in translational research. Using paracetamol as a paradigm compound, we present a novel method to characterize pharmacokinetic processes in zebrafish larvae, by combining sensitive bioanalytical methods and nonlinear mixed effects modeling...
September 15, 2016: Zebrafish
Ge Li, Hang Xie, Dingcong He, Yiping Luo
No abstract text is available yet for this article.
September 8, 2016: Fish Physiology and Biochemistry
Kris Beattie, Brian P Carson, Mark Lyons, Ian C Kenny
Maximum- and reactive-strength qualities both have important roles in athletic movements and sporting performance. Very little research has investigated the relationship between maximum-strength and reactive-strength. The aim of this study was to investigate the relationship between maximum-strength (isometric mid-thigh pull peak force; IMTP PF) and reactive-strength (drop-jump reactive-strength index; DJ-RSI) variables at 0.3 m, 0.4 m, 0.5 m and 0.6 m box heights. A secondary aim investigated the between- and within-group differences in reactive-strength characteristics between relatively 'strong' and 'weak' athletes...
September 6, 2016: International Journal of Sports Physiology and Performance
Maria Myzithras, Tammy Bigwarfe, Hua Li, Erica Waltz, Jennifer Ahlberg, Craig Giragossian, Simon Roberts
Prior to clinical studies, the pharmacokinetics (PK) of antibody-based therapeutics are characterized in preclinical species; however, those species can elicit immunogenic responses that can lead to an inaccurate estimation of PK parameters. Immunodeficient (SCID) transgenic hFcRn and C57BL/6 mice were used to characterize the PK of three antibodies that were previously shown to be immunogenic in mice and cynomolgus monkeys. Four mouse strains, Tg32 hFcRn SCID, Tg32 hFcRn, SCID and C57BL/6, were administered adalimumab (Humira®), mAbX and mAbX-YTE at 1 mg/kg, and in SCID strains there was no incidence of immunogenicity...
September 6, 2016: MAbs
Femke J Taverne, Ingeborg M van Geijlswijk, Dick J J Heederik, Jaap A Wagenaar, Johan W Mouton
BACKGROUND: To optimize antimicrobial dosing in different animal species, pharmacokinetic information is necessary. Due to the plethora of cephalosporin antimicrobials and animal species in which they are used, assessment of pharmacokinetics in all species is unfeasible. In this study we aimed to describe pharmacokinetic data of cephalosporins by reviewing the available literature for food producing and companion animal species. We assessed the accuracy of interspecies extrapolation using allometric scaling techniques to determine pharmacokinetic characteristics of cephalosporins in animal species for which literature data is unavailable...
2016: BMC Veterinary Research
Kevin J Downes, Min Dong, Tsuyoshi Fukuda, John P Clancy, Christopher Haffner, Michael R Bennett, Alexander A Vinks, Stuart L Goldstein
BACKGROUND: Tobramycin is frequently used for treatment of bronchopneumonia in patients with cystic fibrosis (CF). Variability in tobramycin clearance (CL) is high in this population with few reliable approaches to guide dosing. OBJECTIVES: We sought to evaluate the pharmacokinetics of once-daily intravenous tobramycin in patients with CF and test the influence of covariates on tobramycin CL, including serum creatinine (SCr) and urinary biomarkers: neutrophil gelatinase-associated lipocalin (NGAL), retinol-binding protein (RBP) and kidney injury molecule-1 (KIM-1)...
September 1, 2016: Journal of Antimicrobial Chemotherapy
Najia Mansoor, Tasneem Ahmad, Rafeeq Alam Khan, Syed Mohammad Sharib, Iftekhar Mahmod
Children are not small adults because besides size there are subtle physiological and biochemical differences between children and adults. Like adults, children also require medicine for the management or cure for the underlying diseases. To select a right dose in children, pharmacokinetic (PK) information is warranted. However, in many instances, a PK study in neonates and infants may not be possible. Therefore, various methods are used to predict PK parameters in this group of population, and these predicted parameters may help to calculate a safe dose for the very young children...
August 29, 2016: American Journal of Therapeutics
J Häggström, Å O Andersson, T Falk, L Nilsfors, U OIsson, J G Kresken, K Höglund, M Rishniw, A Tidholm, I Ljungvall
BACKGROUND: Echocardiography is a cost-efficient method to screen cats for presence of heart disease. Current reference intervals for feline cardiac dimensions do not account for body weight (BW). OBJECTIVE: To study the effect of BW on heart rate (HR), aortic (Ao), left atrial (LA) and ventricular (LV) linear dimensions in cats, and to calculate 95% prediction intervals for these variables in normal adult pure-bred cats. ANIMALS: 19 866 pure-bred cats...
September 2016: Journal of Veterinary Internal Medicine
Laura W de Jong, Jean-Sébastien Vidal, Lars E Forsberg, Alex P Zijdenbos, Thaddeus Haight, Sigurdur Sigurdsson, Vilmundur Gudnason, Mark A van Buchem, Lenore J Launer
There is growing evidence that sub-structures of the brain scale allometrically to total brain size, that is, in a non-proportional and non-linear way. Here, scaling of different volumes of interest (VOI) to intra-cranial volume (ICV) was examined. It was assessed whether scaling was allometric or isometric and whether scaling coefficients significantly differed from each other. We also tested to what extent allometric scaling of VOI was introduced by the automated segmentation technique. Furthermore, reproducibility of allometric scaling was studied different age groups and study populations...
August 25, 2016: Human Brain Mapping
Elisa A M Calvier, Elke H J Krekels, Pyry A J Välitalo, Amin Rostami-Hodjegan, Dick Tibboel, Meindert Danhof, Catherijne A J Knibbe
Allometric scaling on the basis of bodyweight raised to the power of 0.75 (AS0.75) is frequently used to scale size-related changes in plasma clearance (CLp) from adults to children. A systematic assessment of its applicability is undertaken for scenarios considering size-related changes with and without maturation processes. A physiologically-based pharmacokinetic (PBPK) simulation workflow was developed in R for 12,620 hypothetical drugs. In scenario one, only size-related changes in liver weight, hepatic blood flow, and glomerular filtration were included in simulations of 'true' paediatric CLp...
August 10, 2016: Clinical Pharmacokinetics
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