Publications by authors named "A Biewener"

217 Publications

White Paper: An Integrated Perspective on the Causes of Hypometric Metabolic Scaling in Animals.

Integr Comp Biol 2022 Aug 6. Epub 2022 Aug 6.

Division of Physical & Biological Sciences, University of California Santa Cruz Santa Cruz, CA, USA.

Larger animals studied during ontogeny, across populations, or across species, usually have lower mass-specific metabolic rates than smaller animals (hypometric scaling). This pattern is usually observed regardless of physiological state (e.g. basal, resting, field, maximally-active). The scaling of metabolism is usually highly correlated with the scaling of many life history traits, behaviors, physiological variables, and cellular/molecular properties, making determination of the causation of this pattern challenging. For across-species comparisons of resting and locomoting animals (but less so for across populations or during ontogeny), the mechanisms at the physiological and cellular level are becoming clear. Lower mass-specific metabolic rates of larger species at rest are due to a) lower contents of expensive tissues (brains, liver, kidneys), and b) slower ion leak across membranes at least partially due to membrane composition, with lower ion pump ATPase activities. Lower mass-specific costs of larger species during locomotion are due to lower costs for lower-frequency muscle activity, with slower myosin and Ca++ ATPase activities, and likely more elastic energy storage. The evolutionary explanation(s) for hypometric scaling remain(s) highly controversial. One subset of evolutionary hypotheses relies on constraints on larger animals due to changes in geometry with size; for example, lower surface-to-volume ratios of exchange surfaces may constrain nutrient or heat exchange, or lower cross-sectional areas of muscles and tendons relative to body mass ratios would make larger animals more fragile without compensation. Another subset of hypotheses suggests that hypometric scaling arises from biotic interactions and correlated selection, with larger animals experiencing less selection for mass-specific growth or neurolocomotor performance. A additional third type of explanation comes from population genetics. Larger animals with their lower effective population sizes and subsequent less effective selection relative to drift may have more deleterious mutations, reducing maximal performance and metabolic rates. Resolving the evolutionary explanation for the hypometric scaling of metabolism and associated variables is a major challenge for organismal and evolutionary biology. To aid progress, we identify some variation in terminology use that has impeded cross-field conversations on scaling. We also suggest that promising directions for the field to move forward include: 1) studies examining the linkages between ontogenetic, population-level, and cross-species allometries, 2) studies linking scaling to ecological or phylogenetic context, 3) studies that consider multiple, possibly interacting hypotheses, and 4) obtaining better field data for metabolic rates and the life history correlates of metabolic rate such as lifespan, growth rate and reproduction.
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http://dx.doi.org/10.1093/icb/icac136DOI Listing
August 2022

Physiology: Woodpecker skulls are not shock absorbers.

Curr Biol 2022 Jul;32(14):R767-R769

Department of Organismic and Evolutionary Biology, Concord Field Station, Harvard University, Cambridge, MA 02138, USA. Electronic address:

Woodpeckers are well-known for their audible percussive wood drilling. A new study shows that these birds benefit from their small size and key skull features to safely hammer at wood for insect food and nesting excavations.
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http://dx.doi.org/10.1016/j.cub.2022.06.037DOI Listing
July 2022

Monteggia fractures: analysis of patient-reported outcome measurements in correlation with ulnar fracture localization.

J Orthop Surg Res 2022 Jun 7;17(1):303. Epub 2022 Jun 7.

University Centre for Orthopaedic, Trauma- and Plastic Surgery (OUPC), University Hospital Carl Gustav Carus, Technical University Dresden, Fetscherstraße 74, 01307, Dresden, Germany.

Background: Monteggia fractures and Monteggia-like lesions result after severe trauma and have high complication rates. Preliminary biomechanical studies suggested a correlation between ulnar fracture localization and clinical result.

Objectives: Key objective was to evaluate whether the site of the ulnar fracture can be correlated to clinical outcome after open reduction and internal stabilization.

Methods: In a retrospective, monocentric study 35 patients who underwent surgical treatment after suffering a Monteggia injury or Monteggia-like lesion were included. Fractures were classified according to Bado and Jupiter, the site of the fracture location at the proximal ulna and regarding the potential accompanying ligamentary injury. In a follow-up examination validated patient-reported outcome measures and functional parameters were evaluated. Furthermore, treatment strategy and complications were analysed.

Results: Mean patient age was 51.9 years (± 18.0). 69% were females (n = 24). Follow-up took place after 50.5 months (± 22.1). Fractures were classified according to Bado (I:2, II:27, III:4, IV:2). Bado II-fractures were further classified according to Jupiter (A:7, B:16, C:3, D:1). Cases were divided into subgroups depending upon the distance of the ulnar fracture site in respect to its distal endpoint (A: < 7 cm and B: > 7 cm). Average overall MEPS was 84.1 (± 19.0). Oxford elbow score and DASH were 37.2 (± 10.5) and 20.4 (± 20.5). Average extension capability reached - 7° (± 7.5). Mean flexion was 134.8° (± 19.7). Average pain according to visual analogue scale was 1.6 (± 1.9). We found no differences between the subgroups regarding the PROMs. Subgroup A displayed a worse extension capability (p = 0.027) and patients were significantly older (p < 0.01). Comparing patients with and without fracture of the radial head, we observed no differences. Patients with an accompanying injury of the coronoid process displayed higher pain levels (p = 0.011), a worse functionality (p = 0.027) and overall lower scoring in PROM.

Conclusion: The presented results suggest that in Monteggia fractures and Monteggia-like lesions, the localization of the ulna fracture can give a hint for its postoperative outcome. However, we could not confirm the hypothesis of an increasing instability in ulnar fractures located further distally (high severity of the potential ligamentous injury). Intraarticular fractures or injuries with a close relation to the joint have a worse prognosis, especially if the coronoid process is injured. Trial registration Registration was done with ClinicalTrials.gov under NCT05325268.
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http://dx.doi.org/10.1186/s13018-022-03195-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9172148PMC
June 2022

Stability and manoeuvrability in animal movement: lessons from biology, modelling and robotics.

Proc Biol Sci 2022 01 19;289(1967):20212492. Epub 2022 Jan 19.

Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.

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http://dx.doi.org/10.1098/rspb.2021.2492DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8767207PMC
January 2022

Correction: Optic flow stabilizes flight in ruby-throated hummingbirds.

J Exp Biol 2021 Feb 24;224(Pt 4). Epub 2021 Feb 24.

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http://dx.doi.org/10.1242/jeb.242423DOI Listing
February 2021
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