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This article is commented on in the editorial by Holford NHG and Anderson BJ. Why standards are useful for predicting doses. Br J Clin Pharmacol 2017; 83: 685–7. doi: ...10.1111/bcp.13230
Aim
When different models for weight and age are used in paediatric pharmacokinetic studies it is difficult to compare parameters between studies or perform model‐based meta‐analyses. This study aimed to compare published models with the proposed standard model (allometric weight0.75 and sigmoidal maturation function).
Methods
A systematic literature search was undertaken to identify published clearance (CL) reports for gentamicin and midazolam and all published models for scaling clearance in children. Each model was fitted to the CL values for gentamicin and midazolam, and the results compared with the standard model (allometric weight exponent of 0.75, along with a sigmoidal maturation function estimating the time in weeks of postmenstrual age to reach half the mature value and a shape parameter). For comparison, we also looked at allometric size models with no age effect, the influence of estimating the allometric exponent in the standard model and, for gentamicin, using a fixed allometric exponent of 0.632 as per a study on glomerular filtration rate maturation. Akaike information criteria (AIC) and visual predictive checks were used for evaluation.
Results
No model gave an improved AIC in all age groups, but one model for gentamicin and three models for midazolam gave slightly improved global AIC fits albeit using more parameters: AIC drop (number of parameters), –4.1 (5), –9.2 (4), –10.8 (5) and –10.1 (5), respectively. The 95% confidence interval of estimated CL for all top performing models overlapped.
Conclusion
No evidence to reject the standard model was found; given the benefits of standardised parameterisation, its use should therefore be recommended.
Abstract
Sexual dimorphism describes phenotypic differences between the sexes; the most prominent of which is sexual size dimorphism (SSD). Rensch’s rule (RR) is an allometric trend in which SSD ...increases in male-larger taxa and decreases in female-larger ones. Covariation between a trait and overall size within and across species can both be affected by sexual and natural selection. Thus, intraspecific allometric variation could influence the expression of RR. Here we used computer simulations to dissect how RR emerges under specific allometric patterns of intraspecific sexual differentiation in a trait. We found that sexual differentiation in static allometric slopes is the main determinant of RR. Based on our findings, RR and its converse can manifest in both body size and other traits. As a realistic showcase, we also examined RR and static allometry of different body parts in Mediterranean green lizards to establish whether intraspecific and evolutionary allometry are linked. Here, we identified RR and its converse for different traits, where the amount of sexual differentiation in static allometric slopes within species had a significant contribution to RR. Integrating the simulations and the empirical case we corroborate that sexual differentiation in static allometric slopes is a major parameter affecting evolutionary allometry.
Abstract Height–diameter (H-D) allometric relationships provide us with insights into tree growth strategies and resource utilization. Yet, we have a poor understanding about the underlying drivers ...that limit or alter tree H-D allometries at large scales. Based on 569 502 pairs of height versus diameter from 53 808 plots of 20 species in the Rocky Mountains, USA, we used a mixed-effects approach to model the variability in H-D allometry across species (interspecific variation) and within-species (intraspecific variation) along gradients of site condition, climate, and competition. The allometric theories derived from physics or biological laws provide a fundamental framework for tree growth and performance, but our findings also show that physiological and environmental factors further shape the interspecific and intraspecific patterns in tree allometry with the intraspecific variation being smaller than the interspecific variation along all the gradients we considered. In general, trees growing in favorable site conditions and highly competitive environments tend to comparatively invest more in height growth, while trees may preferentially invest in diameter growth when constrained by water stress or other unfavorable climatic condition. Trees will choose the most appropriate growth strategies with corresponding allometric patterns to adapt to environmental changes. Our study is expected to provide applied value for estimating biomass and carbon stocks at broad environmental scales.
Hatching success and failure is influences by the interaction between biotic and abiotic factors during the incubation period. Non optimal nest is susceptible to bacterial contaminated eggs during ...incubation period and hatchling morphology. The purpose of the study is to understand the relationship between environmental conditions of semi natural nest with bacteria contaminant, hatchlings allometry and abnormality. The method used was quantitative descriptive which are nest temperature and humidity measurement, hatchlings allometry measurement, bacteria observation of gram negative with EMB (Eosin Methylene Blue) agar, TPC (Total Plate Count), bacteria characteristic morphology and hatchlings abnormality observation. The result showed that semi natural nest have high temperature (30˚C) and high humidity (70%) caused smaller hatchlings and negative allometry growth, hatchlings abnormality and bacterial contaminant. TPC showed that the number of bacteria unhatched eggs (1,42 x ) more than hatched eggs (1,03 x ). The bacteria colonies were suspected to be from Enterobacteriaceae family according to microscopic and macroscopic morphological characteristic. Macroscopically, the bacteria morphology is dominated by a round shape, concentric surface, flat edges, flat elevation and pink color, meanwhile microscopic form is bacilli. There is significant correlation between environmental conditions of semi natural nest with hatchlings growth, hatchlings abnormality and eggshells bacteria
Blue swimming crab (BSC) (Portunus pelagicus) is the main fisheries commodity in Banten Bay, with the highest catch of catch occurring in the west monsoon. Increased fishing efforts have reduced the ...catch, as indicated by a decrease in the average size of carapace width. Overfishing might influence the life cycle and population structure of the BSC. This research aims to analyze the growth and mortality of the Blue Swimming Crab in Banten Bay, especially in the west monsoon. Blue swimming crab samples were obtained from the catch of fish trap and gillnet fishermen with landing sites around the Karangantu Archipelago Fishing Port. Growth, age, and mortality were predicted based on the measurement of total carapace width and body weight. Data were analyzed using Fisat II and Microsoft Excel. The frequency distribution of carapace showed one mode class which normally was distributed consisting of only one age structure group (cohort). The relationship between carapace width and weight of males or females resulted in a slope value (b>3) and was positive allometric, indicating that both sexes had a faster weight gain than the increase in carapace width. Growth parameters resulted asymptotic length (L∞); male 176.75 mm and female 176.46 mm. The growth was relatively fast, with a growth coefficient value of more than one. The mortality showed that the fishing mortality value (F);in males was 3.47 /year and in females 2.69/year was greater than the natural mortality value (M); males 1.25/year and females 1.22/year. Blue Swimming Crabs in Banten Bay had overfished as shown by the high fishing mortality value and there were still many BSC that were caught below the legal size allowed. Thus, catches should be controlled to keep the population and for sustainable fisheries.
Correct estimation of tree biomass is important when calculating uptake or emission of CO2 in relation to land-use and land-use change. The objectives of this study were (1) to estimate the ...root/shoot ratio for the estimation of root biomass based on the above-ground biomass (AGB) of Acacia mearnsii, and (2) to develop allometric equations for the estimation of the above-and below-ground biomass (BGB) of Acacia mearnsii. To estimate the AGB and BGB, twenty-four trees of varying ages (3, 4, 5, and 6 years) were harvested, with six trees per age group. We measured the dry biomass for different tree parts and developed allometric models using tree height (H) and diameter at breast height (DBH) as independent variables. The results showed that the biomass of the stem accounted for 69% of the total biomass, followed by branches (14%), roots (8.1%), and leaves (7.3%). The recorded mean root/shoot ratio was 0.11. The biomass of the stem and coarse roots increased with increasing tree age, while a contrary trend was observed for the other tree components. Each component has its unique allometric model.
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•PK predictions.•Inter-drug approach.•Comparison of translation methods.•Single animal translation.•in vitro-in vivo.
An inter-drug approach, applying pharmacokinetic information for ...insulin analogs in different animal species, rat, dog and pig, performed better compared to allometric scaling for human translation of intra-venous half-life and only required data from a single animal species for reliable predictions. Average fold error (AFE) between 1.2–1.7 were determined for all species and for multispecies allometric scaling AFE was 1.9. A slightly larger prediction error for human half-life was determined from in vitro human insulin receptor affinity data (AFE on 2.3–2.6). The requirements for the inter-drug approach were shown to be a span of at least 2 orders of magnitude in half-life for the included drugs and a shared clearance mechanism.
The insulin analogs in this study were the five fatty acid protracted analogs: Insulin degludec, insulin icodec, insulin 320, insulin 338 and insulin 362, as well as the non-acylated analog insulin aspart.
In this study, data on length and weight of fish were used to determine the length-weight relationship and condition factors of eight fish species that are targeted by traditional Papuan fishers and ...have high economic value (Lutjanus fulvus, Gerres oyena, Parupeneus barberinus, Siganus spinus, Siganus canaliculatus, Pelates quadrilineatus. Mugil cephalus, and Hemiramphus far) in Youtefa Bay, Papua Province, Indonesia. A total of 245 fish specimens were collected from Papuan fishermen during the period January to March 2020. The total length and body-weight of the fish specimens studied ranged from 15.2 to 32.1 cm (average 20.26±3.73 cm) and 42.72 to 371.86 g (average 124.10±52.45 g), respectively. The b value for all fish species studied ranged from 2.6919 to 3.0791, with the coefficient of determination (R2) ranging from 0.9022 to 0.9947. The growth patterns of the eight fish species were allometric (b ≠ 3; t-test < t-tab), where L. fulvus (2.824), P. barberinus (2.9136), S. canaliculatus (2.989), P. quadrilineatus (2.9577), M. cephalus (2.9096), and H. far (2.6919) were negative allometric (b < 3), while G. oyena (3.0596) and S. spinus (3.0791) are positive allometric (b > 3). Meanwhile, the relative condition factor and Fulton condition factor values ranged from 0.874 to 1.201 (average 0.999±0.321) and 0.204 to 2.726 (average 1.612±0.515). M. cephalus had a higher relative condition factor, while L. fulvus had a higher Fulton condition factor than other fish species
Cell size correlates with most traits among phytoplankton species. Theory predicts that larger cells should show poorer photosynthetic performance, perhaps due to reduced intracellular self-shading ...(i.e. package effect). Yet current theory relies heavily on interspecific correlational approaches and causal relationships between size and photosynthetic machinery have remained untested.
As a more direct test, we applied 250 generations of artificial selection (c. 20 months) to evolve the green microalga Dunaliella teriolecta (Chlorophyta) toward different mean cell sizes, while monitoring all major photosynthetic parameters.
Evolving larger sizes (> 1500% difference in volume) resulted in reduced oxygen production per chlorophyll molecule – as predicted by the package effect. However, large-evolved cells showed substantially higher rates of oxygen production – a finding unanticipated by current theory. In addition, volume-specific photosynthetic pigments increased with size (Chla+b), while photo-protectant pigments decreased (β-carotene). Finally, larger cells displayed higher growth performances and F
v/F
m, steeper slopes of rapid light curves (α) and smaller ligh-tharvesting antennae (σPSII) with higher connectivity (ρ).
Overall, evolving a common ancestor into different sizes showed that the photosynthetic characteristics of a species coevolves with cell volume. Moreover, our experiment revealed a trade-off between chlorophyll-specific (decreasing with size) and volume-specific (increasing with size) oxygen production in a cell.
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