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A low protein diet alters bone material level properties and the response to in vitro repeated mechanical loading.

Dubois-Ferrière V, Rizzoli R, Ammann P - Biomed Res Int (2014)

Bottom Line: However, it remains unknown whether these alterations of bone tissue could influence the response to repeated mechanical loading.Humeri were then monotonically loaded to failure.Material level properties were also evaluated through a nanoindentation test.

View Article: PubMed Central - PubMed

Affiliation: Division of Bone Diseases, Department of Internal Medicine Specialties, University of Geneva Hospitals and Faculty of Medicine, 4 Rue Gabrielle Perret-Gentil, 1211 Geneva 14, Switzerland.

ABSTRACT
Low protein intake is associated with an alteration of bone microstructure and material level properties. However, it remains unknown whether these alterations of bone tissue could influence the response to repeated mechanical loading. The authors investigated the in vitro effect of repeated loading on bone strength in humeri collected from 20 6-month-old female rats pair-fed with a control (15% casein) or an isocaloric low protein (2.5% casein) diet for 10 weeks. Bone specimens were cyclically loaded in three-point bending under load control for 2000 cycles. Humeri were then monotonically loaded to failure. The load-displacement curve of the in vitro cyclically loaded humerus was compared to the contralateral noncyclically loaded humerus and the influence of both protein diets. Material level properties were also evaluated through a nanoindentation test. Cyclic loading decreased postyield load and plastic deflection in rats fed a low protein diet, but not in those on a regular diet. Bone material level properties were altered in rats fed a low protein diet. This suggests that bone biomechanical alterations consequent to cyclic loading are more likely to occur in rats fed a low protein diet than in control animals subjected to the same in vitro cyclic loading regimen.

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Related in: MedlinePlus

Schematic representation of a load-deflection curve corresponding to a bending test of a bone diaphysis.
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fig1: Schematic representation of a load-deflection curve corresponding to a bending test of a bone diaphysis.

Mentions: Deflection (mm) and load (N) were simultaneously recorded every 0.01 s and the load-deflection curve was recorded (Figure 1). Maximal load (LMAX (N)), stiffness (slope of the elastic part of the curve (N/mm)), yield point (LY, point separating the elastic part and the plastic part of the curve (N)), postyield load (maximal load (LMAX) minus yield point load (LY) (N)), and postyield displacement (mm) were directly obtained from the load-deflection curve and automatically calculated. The energy absorbed by the bone tissue (area under the load-deflection curve before the bone breaks (N × mm)), plastic energy (mJ), and elastic energy (mJ) were also calculated.


A low protein diet alters bone material level properties and the response to in vitro repeated mechanical loading.

Dubois-Ferrière V, Rizzoli R, Ammann P - Biomed Res Int (2014)

Schematic representation of a load-deflection curve corresponding to a bending test of a bone diaphysis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150450&req=5

fig1: Schematic representation of a load-deflection curve corresponding to a bending test of a bone diaphysis.
Mentions: Deflection (mm) and load (N) were simultaneously recorded every 0.01 s and the load-deflection curve was recorded (Figure 1). Maximal load (LMAX (N)), stiffness (slope of the elastic part of the curve (N/mm)), yield point (LY, point separating the elastic part and the plastic part of the curve (N)), postyield load (maximal load (LMAX) minus yield point load (LY) (N)), and postyield displacement (mm) were directly obtained from the load-deflection curve and automatically calculated. The energy absorbed by the bone tissue (area under the load-deflection curve before the bone breaks (N × mm)), plastic energy (mJ), and elastic energy (mJ) were also calculated.

Bottom Line: However, it remains unknown whether these alterations of bone tissue could influence the response to repeated mechanical loading.Humeri were then monotonically loaded to failure.Material level properties were also evaluated through a nanoindentation test.

View Article: PubMed Central - PubMed

Affiliation: Division of Bone Diseases, Department of Internal Medicine Specialties, University of Geneva Hospitals and Faculty of Medicine, 4 Rue Gabrielle Perret-Gentil, 1211 Geneva 14, Switzerland.

ABSTRACT
Low protein intake is associated with an alteration of bone microstructure and material level properties. However, it remains unknown whether these alterations of bone tissue could influence the response to repeated mechanical loading. The authors investigated the in vitro effect of repeated loading on bone strength in humeri collected from 20 6-month-old female rats pair-fed with a control (15% casein) or an isocaloric low protein (2.5% casein) diet for 10 weeks. Bone specimens were cyclically loaded in three-point bending under load control for 2000 cycles. Humeri were then monotonically loaded to failure. The load-displacement curve of the in vitro cyclically loaded humerus was compared to the contralateral noncyclically loaded humerus and the influence of both protein diets. Material level properties were also evaluated through a nanoindentation test. Cyclic loading decreased postyield load and plastic deflection in rats fed a low protein diet, but not in those on a regular diet. Bone material level properties were altered in rats fed a low protein diet. This suggests that bone biomechanical alterations consequent to cyclic loading are more likely to occur in rats fed a low protein diet than in control animals subjected to the same in vitro cyclic loading regimen.

Show MeSH
Related in: MedlinePlus