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3D finite compartment modeling of formation and healing of bruises may identify methods for age determination of bruises.

Stam B, van Gemert MJ, van Leeuwen TG, Aalders MC - Med Biol Eng Comput (2010)

Bottom Line: We developed a numerical 3D model to simulate the spatial kinetics of hemoglobin and bilirubin during the formation and healing of bruises.Healing is faster for smaller bruises in thinner and less dense skin.Combining our model predictions with individual natural bruises may allow optimizing our model parameters.

View Article: PubMed Central - PubMed

Affiliation: Biomedical Engineering and Physics, Academic Medical Centre, Amsterdam, The Netherlands. b.stam@amc.nl

ABSTRACT
Simulating the spatial and temporal behavior of bruises may identify methods that allow accurate age determination of bruises to assess child abuse. We developed a numerical 3D model to simulate the spatial kinetics of hemoglobin and bilirubin during the formation and healing of bruises. Using this model, we studied how skin thickness, bruise diameter and diffusivities affect the formation and healing of circular symmetric bruises and compared a simulated bruise with a natural inhomogeneous bruise. Healing is faster for smaller bruises in thinner and less dense skin. The simulated and natural bruises showed similar spatial and temporal dynamics. The different spatio-temporal dynamics of hemoglobin and bilirubin allows age determination of model bruises. Combining our model predictions with individual natural bruises may allow optimizing our model parameters. It may particularly identify methods for more accurate age determination than currently possible to aid the assessment of child abuse.

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a The skin model consists of 3 layers, the top layer of the dermis, the bottom layer of the dermis and the subcutaneous fat layer. Each layer consists of 100¬†√ó¬†100 compartmets (for ease of presentation a smaller number is shown). b and c A pool of hemoglobin is defined in the subcutaneous layer. Via Michealis‚ÄďMenten kinetics the hemoglobin is converted into bilirubin. Both hemoglobin and bilirubin flow inside the layers and between the layers
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Fig1: a The skin model consists of 3 layers, the top layer of the dermis, the bottom layer of the dermis and the subcutaneous fat layer. Each layer consists of 100¬†√ó¬†100 compartmets (for ease of presentation a smaller number is shown). b and c A pool of hemoglobin is defined in the subcutaneous layer. Via Michealis‚ÄďMenten kinetics the hemoglobin is converted into bilirubin. Both hemoglobin and bilirubin flow inside the layers and between the layers

Mentions: The model of the skin consists of three layers; the top layer of the dermis (layer 1), the bottom layer of the dermis (layer 2) and the subcutaneous tissue layer (layer 3). Each layer is subdivided into 100¬†√ó¬†100 corresponding compartments as schematically shown in Fig.¬†1a. For ease of analysis, all compartments have the same lateral dimensions equal to the thickness of the total dermis, and the thickness of the layers can be varied to account for inter-individual variability or body location. The initial condition of the bruise is modeled by a pool of hemoglobin of arbitrary shape and size in the subcutaneous tissue (Fig.¬†1b). The bruise develops over time by conversion of hemoglobin into bilirubin and transport of these molecules via pressure driven flow, i.e. convection and concentration driven diffusion. The concentration of hemoglobin within a compartment may change by three processes: (1) convection in vertical direction from the subcutaneous tissue layer into the dermis (Fig.¬†1b), (2) vertical diffusion between the layers, as well as horizontal diffusion within the layers (Fig.¬†1c), (3) enzymatic conversion of hemoglobin to bilirubin. Darcy‚Äôs law for transport of fluids describes the convection of hemoglobin in vertical direction, assuming no pressure gradient in horizontal direction, hence neglects flow in horizontal direction (first right hand term in Eq.¬†1). Diffusion, in vertical and horizontal direction, follows concentration gradients and is described by the first law of Fick (second right hand term in Eq.¬†1). The enzyme-controlled conversion of hemoglobin to bilirubin is described by Michaelis‚ÄďMenten kinetics [1] (third right hand term in Eq.¬†1). We will first present the formula for compartments in layer 2, from which the formulas for layers 1 and 3 follow.Fig.¬†1


3D finite compartment modeling of formation and healing of bruises may identify methods for age determination of bruises.

Stam B, van Gemert MJ, van Leeuwen TG, Aalders MC - Med Biol Eng Comput (2010)

a The skin model consists of 3 layers, the top layer of the dermis, the bottom layer of the dermis and the subcutaneous fat layer. Each layer consists of 100¬†√ó¬†100 compartmets (for ease of presentation a smaller number is shown). b and c A pool of hemoglobin is defined in the subcutaneous layer. Via Michealis‚ÄďMenten kinetics the hemoglobin is converted into bilirubin. Both hemoglobin and bilirubin flow inside the layers and between the layers
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2926474&req=5

Fig1: a The skin model consists of 3 layers, the top layer of the dermis, the bottom layer of the dermis and the subcutaneous fat layer. Each layer consists of 100¬†√ó¬†100 compartmets (for ease of presentation a smaller number is shown). b and c A pool of hemoglobin is defined in the subcutaneous layer. Via Michealis‚ÄďMenten kinetics the hemoglobin is converted into bilirubin. Both hemoglobin and bilirubin flow inside the layers and between the layers
Mentions: The model of the skin consists of three layers; the top layer of the dermis (layer 1), the bottom layer of the dermis (layer 2) and the subcutaneous tissue layer (layer 3). Each layer is subdivided into 100¬†√ó¬†100 corresponding compartments as schematically shown in Fig.¬†1a. For ease of analysis, all compartments have the same lateral dimensions equal to the thickness of the total dermis, and the thickness of the layers can be varied to account for inter-individual variability or body location. The initial condition of the bruise is modeled by a pool of hemoglobin of arbitrary shape and size in the subcutaneous tissue (Fig.¬†1b). The bruise develops over time by conversion of hemoglobin into bilirubin and transport of these molecules via pressure driven flow, i.e. convection and concentration driven diffusion. The concentration of hemoglobin within a compartment may change by three processes: (1) convection in vertical direction from the subcutaneous tissue layer into the dermis (Fig.¬†1b), (2) vertical diffusion between the layers, as well as horizontal diffusion within the layers (Fig.¬†1c), (3) enzymatic conversion of hemoglobin to bilirubin. Darcy‚Äôs law for transport of fluids describes the convection of hemoglobin in vertical direction, assuming no pressure gradient in horizontal direction, hence neglects flow in horizontal direction (first right hand term in Eq.¬†1). Diffusion, in vertical and horizontal direction, follows concentration gradients and is described by the first law of Fick (second right hand term in Eq.¬†1). The enzyme-controlled conversion of hemoglobin to bilirubin is described by Michaelis‚ÄďMenten kinetics [1] (third right hand term in Eq.¬†1). We will first present the formula for compartments in layer 2, from which the formulas for layers 1 and 3 follow.Fig.¬†1

Bottom Line: We developed a numerical 3D model to simulate the spatial kinetics of hemoglobin and bilirubin during the formation and healing of bruises.Healing is faster for smaller bruises in thinner and less dense skin.Combining our model predictions with individual natural bruises may allow optimizing our model parameters.

View Article: PubMed Central - PubMed

Affiliation: Biomedical Engineering and Physics, Academic Medical Centre, Amsterdam, The Netherlands. b.stam@amc.nl

ABSTRACT
Simulating the spatial and temporal behavior of bruises may identify methods that allow accurate age determination of bruises to assess child abuse. We developed a numerical 3D model to simulate the spatial kinetics of hemoglobin and bilirubin during the formation and healing of bruises. Using this model, we studied how skin thickness, bruise diameter and diffusivities affect the formation and healing of circular symmetric bruises and compared a simulated bruise with a natural inhomogeneous bruise. Healing is faster for smaller bruises in thinner and less dense skin. The simulated and natural bruises showed similar spatial and temporal dynamics. The different spatio-temporal dynamics of hemoglobin and bilirubin allows age determination of model bruises. Combining our model predictions with individual natural bruises may allow optimizing our model parameters. It may particularly identify methods for more accurate age determination than currently possible to aid the assessment of child abuse.

Show MeSH
Related in: MedlinePlus