Skin Grafting Chris Agam OReilly€¦ · Skin y Largest organ y Protects from dehydration,...
Transcript of Skin Grafting Chris Agam OReilly€¦ · Skin y Largest organ y Protects from dehydration,...
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Skin GraftingChris Agam
Jason OReilly
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Skin
Largest organ Protects from dehydration, chemicals, temperature controlThree basic layers
Epidermis, made of keratinocytesDermis, made of fibroblast, vasculature and collagenHypodermis, made adipose and macrophages [1]
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Model of Skin
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8 axis of stress were appliedin vivo
Tested expansion andcontraction
800 data point were usedto find stress and strain on 4 subjects [2]
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Model Of Skin
From Fung’s equation of Langer line
Giving partial derivatives
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Model of Skin
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Wound Healing
Stages1) Inflammation2) Granulation , scar tissue3) Epithelial layer start to form4) Collagen/Fibrin matrix forms [3]
Skin can’t grow on direct bone, nerves or cartilage without appropriate natural covers[4]
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When Are Skin Grafts Used?
In cases where large portions of skin are lost beyond the ability of unassisted repairCommonly used in burn victims and for cosmetic reasons
Skin grafts are important for structural features:Sweat glands to regulate temperatureProtection of innardsNerves for feeling of sensation, pain, heat, and cold[1]
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Historically
1785 – Giuseppe Baronio’s
research resulted in first successful skin grafts in animals[5]
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1823 ‐
Christian Bünger
performed the first clinical skin graft on the nose
1869 ‐
Jacques‐Louis Reverdin
Pinch graft
1870‐
Paul Bert investigated the biocompatibility of skin grafts
1870 –
George Lawson first full‐thickness graft [5]
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1823 ‐
Christian Bünger
performed the first clinical skin graft on the nose
1869 ‐
Jacques‐Louis Reverdin
Pinch graft
1870‐
Paul Bert investigated the biocompatibility of skin grafts
1870 –
George Lawson first full‐thickness graft [5]
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1823 ‐
Christian Bünger
performed the first clinical skin graft on the nose
1869 ‐
Jacques‐Louis Reverdin
Pinch graft
1870‐
Paul Bert investigated the biocompatibility of skin grafts
1870 –
George Lawson first full‐thickness graft [5]
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1823 ‐
Christian Bünger
performed the first clinical skin graft on the nose
1869 ‐
Jacques‐Louis Reverdin
Pinch graft
1870‐
Paul Bert investigated the biocompatibility of skin grafts
1870 –
George Lawson first full‐thickness graft [5]
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1823 ‐
Christian Bünger
performed the first clinical skin graft on the nose
1869 ‐
Jacques‐Louis Reverdin
Pinch graft
1870‐
Paul Bert investigated the biocompatibility of skin grafts
1870 –
George Lawson first full‐thickness graft [5]
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1874 –
Thiersch
began usage of thin skin grafts[5]
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At the same time, Wolfe was making advancements in full thickness grafts, which became known as “Wolfe” grafts[5]
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1929 – Blair split skin graftBlair and Barret‐Brown invented the electric
dermatome making skin removal less error prone[5]
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1960 –
Medawar won the Nobel Prize and was eventually knighted for his work on skin graft
rejection[5]
Medawar studied the immunological response of skin grafts using homozygote twins and chimeras
He studied what made grafts tolerable
Found that mice can become tolerant to a specific donor
If the mouse is injected with lymphoid from another non‐tolerated donor, the graft will be rejected[6,12]
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1960 –
Medawar won the Nobel Prize and was eventually knighted for his work on skin graft
rejection[5]
Medawar studied the immunological response of skin grafts using homozygote twins and chimeras
He studied what made grafts tolerable
Found that mice can become tolerant to a specific donor
If the mouse is injected with lymphoid from another non‐tolerated donor, the graft will be rejected[6,12]
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1960 –
Medawar won the Nobel Prize and was eventually knighted for his work on skin graft
rejection[5]
Medawar studied the immunological response of skin grafts using homozygote twins and chimeras
He studied what made grafts tolerable
Found that mice can become tolerant to a specific donor
If the mouse is injected with lymphoid from another non‐tolerated donor, the graft will be rejected[6,12]
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1960 –
Medawar won the Nobel Prize and was eventually knighted for his work on skin graft
rejection[5]
Medawar studied the immunological response of skin grafts using homozygote twins and chimeras
He studied what made grafts tolerable
Found that mice can become tolerant to a specific donor
If the mouse is injected with lymphoid from another non‐tolerated donor, the graft will be rejected[6,12]
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1960 –
Medawar won the Nobel Prize and was eventually knighted for his work on skin graft
rejection[5]
Medawar studied the immunological response of skin grafts using homozygote twins and chimeras
He studied what made grafts tolerable
Found that mice can become tolerant to a specific donor
If the mouse is injected with lymphoid from another non‐tolerated donor, the graft will be rejected[6,12]
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•Classic skin graft•Artificial skin graft
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Skin Grafts: The Basics
For a skin graft to survive, three conditions must be met:
1.
Potential for survival after removal
2.
Recipient site must have vascular supply
3.
The local environment must be favorable so the attachment will occur[9]
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Where Does One Cuts the Dermis?
Varying thickness of the dermis yield differing results due to the different material aspects of the dermis at different levels[9].
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Split Thickness Graft
Consists of epidermis and portion of the dermisThe portion of the dermis taken depends on the specific case[10]
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Thin Skin Grafts
The upper portion of the dermis gives rise to the following properties of thin grafts:
1. Dermal blood vesicles arborize
as they rise in the
dermis2.
Finer capillary network
3.
Less volume to vascularize[10]
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Thin Skin Grafts
The upper portion of the dermis gives rise to the following properties of thin grafts:
1. Dermal blood vesicles arborize
as they rise in the
dermis2.
Finer capillary network
3.
Less volume to vascularize[10]
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Skin is often glossy
Skin is pale and contrasts markedly with skin
Coarseness of damaged area will be evident through the skin[9,10]
Thin Skin GraftsPros Cons
Can heal quickly
Does not damage donor site as much
Donor site heals faster allowing for more transplants
Can cover larger area and greater chance of survival
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Skin is often glossy
Skin is pale and contrasts markedly with skin
Coarseness of damaged area will be evident through the skin[9,10]
Thin Skin GraftsPros Cons
Can heal quickly
Does not damage donor site as much
Donor site heals faster allowing for more transplants
Can cover larger area and greater chance of survival
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Thick Skin Grafts
The biomaterials of the lower dermis causes the following benefits for thick grafts:
1.
Less susceptible to traumatic injury
2.
Better cosmetic result[10]
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Thick Skin GraftsPros Cons
Less susceptible to traumatic injury, acts as a cushion
Increase in elasticity
Better cosmetic result, more natural complexion
Takes longer to heal
Difficult to find large suitable donor sites
Donor site takes longer to heal[9,10]
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Thick Skin GraftsPros Cons
Less susceptible to traumatic injury, acts as a cushion
Increase in elasticity
Better cosmetic result, more natural complexion
Takes longer to heal
Difficult to find large suitable donor sites
Donor site takes longer to heal[9,10]
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Donor Site Location
The donor site for the skin graft must have very similar biomaterial properties to the grafting location
For instance, for a facial graft the donor site is often the upper shoulders due to similarities to facial skin
The graft will retain the properties of the donor site[10]
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The most important factor for graft survival is the preparation of the recipient site
The site must meet physiologic conditions to be accepted and nourished
Skin grafts cannot be done directly on bone, cartilage, tendon, or nerve without the respective coverings[14]
Graft Survival
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The most important factor for graft survival is the preparation of the recipient site
The site must meet physiologic conditions to be accepted and nourished
Skin grafts cannot be done directly on bone, cartilage, tendon, or nerve without the respective coverings[14]
Graft Survival
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The most important factor for graft survival is the preparation of the recipient site
The site must meet physiologic conditions to be accepted and nourished
Skin grafts cannot be done directly on bone, cartilage, tendon, or nerve without the respective coverings[14]
Graft Survival
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The most important factor for graft survival is the preparation of the recipient site
The site must meet physiologic conditions to be accepted and nourished
Skin grafts cannot be done directly on bone, cartilage, tendon, or nerve without the respective coverings[14]
Graft Survival
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Operation Techniques
Each type of skin graft has their own specific operating techniquesAll grafts general begin with the following treatment of the donor site:
1.
Anesthesia2.
Epinephrine for vasoconstriction(optional)
3.
Anti‐bacteria agents[9]
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Full Thickness Operation
The skin is marked, treated and removed using a scalpel to incise the markings, and a skin hook to remove the skin itself
Adipose tissue is removed from the bottom of the dermis since it has poor vascularization [9]
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Split thickness may be harvested several ways
The most commonly used instrument is the blade dermatome using an rapidly oscillating blade
Some surgeons use manual equipment, knifes or scalpel to remove skin for irregular patterns[11]
Split‐thickness Operation
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Split thickness may be harvested several ways
The most commonly used instrument is the blade dermatome using an rapidly oscillating blade
Some surgeons use manual equipment, knifes or scalpel to remove skin for irregular patterns[11]
Split‐thickness Operation
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Meshing
A split‐thickness skin graft may be meshed by running it through a mechanical meshing unitThis allows for expansion of the surface area as needed for patients where only small donation sites are available[9]
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Inserting the Graft
Recipient site must be inspected for hemostatis
The graft should fit perfectly into place to maximize peripheral contact and surface contact with no folds for more vascularization
Suturing or stapling of the graft reinforce contact[9]
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Post‐graft
Adherence to wound bed via thin fibrin network
Period of time between grafting and revascularization
Full circulation after just 7 days[9]
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Wound Contraction
During healing, contraction may cause serious functional or cosmetic problems as a result of differing properties of donor and recipient areas
Over joints, contraction can cause decease in range of motion[10]
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Regeneration
Hair will rarely grow from thin graftsSweat glands and sebaceous glands may regenerate depending on thickness of graft and depends on the recipient siteNerve fibers will regenerate in thin grafts fasterSkin will be dry and scaly until sweat glands regain function[4]
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Reinnervation
Occurs initially on periphery of graft and proceeds inwardsThis process may take several yearsFull thickness grafts reinnervated more completely
PigmentationFull‐thickness grafts are likely to retain complexion of donor siteThinner grafts may remain pale or possibly hyperpigmentation may occur[15]
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Reinnervation
Occurs initially on periphery of graft and proceeds inwardsThis process may take several yearsFull thickness grafts reinnervated more completely
PigmentationFull‐thickness grafts are likely to retain complexion of donor siteThinner grafts may remain pale or possibly hyperpigmentation may occur[15]
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Graft Failure
Most common source of failure is poor adhesion to recipient siteShearing forces or movement of the graftPoor vascularization of recipient siteContamination and immune responses leading to inflammation and deterioration of fibrin[10]
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Skin Culture: History
1975 – Rheinwald and Green culture the first skin transplant (multiple layers of keratinocytes)
1981 – O’Connor completes the firsthuman transplant with at cultured epithelial autograph (CEA)[1]
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Skin Banks
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By 2016 half of the orthopaedic surgery will need banked tissue
Typically 34,000‐62,000 grafts per year in Canada
Projected increase of 10,000 per year (2006)
Tissue supply is not where the demand is
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Building CEA
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Grown on scaffolds that are natural to the human body or biodegradable
Scaffold material like collagen and fibrin are ideal
keratinocytes are “seeded” on to the scaffold with a culture medium in a bioreactor
Typically take 3 week to enough skin to perform a graft
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Building CEA
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A fibrin matrix , is biocompatible is the glue of the healing process
Fibrin helps reduce the riskof rejection
The matrix allows for thicker CEA with more layers
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Building CEA
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CEAPros Cons
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Great temporal patch to assist in wound healing
Bio dressing
Thin skin graft alternative
Grafts beyond the epidermis
Very fragile, weak against shear stress
Open to infection, due to the protection of multiple layer
Biocompatibility, lack of integrin
Expensive and labour intensive[1]
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Extra Cellular Material
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Full thickness grafts
Multiple cell types
3‐D scaffolding
Improve vasculature
Better integration with the body[1]
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ECM
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Multiple cell layersEpitheal cellDermal cellBasement cells
More complex ECMstructure
Better cell development
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ECM
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Multiple cell layersEpitheal cellDermal cellBasement cells
More complex ECMstructure
Better cell development
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Composite Skin Stress vs. Strain
Artificial skin grafts attempt to have properties as close to human skin as possibleIn experiments using mice, they analyzed these properties with various composite skinsThey used a xenogeneic acellular dermal matrix Dermal papilla cells were placed on this matrixIn the control group, DPCs were not used
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[13]
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Composite Skin Stress vs. Strain
Artificial skin grafts attempt to have properties as close to human skin as possibleIn experiments using mice, they analyzed these properties with various composite skinsThey used a xenogeneic acellular dermal matrix Dermal papilla cells were placed on this matrixIn the control group, DPCs were not used
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[13]
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Composite Skin Stress vs. Strain
Artificial skin grafts attempt to have properties as close to human skin as possibleIn experiments using mice, they analyzed these properties with various composite skinsThey used a xenogeneic acellular dermal matrix Dermal papilla cells were placed on this matrixIn the control group, DPCs were not used
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[13]
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Composite Skin Stress vs. Strain
Artificial skin grafts attempt to have properties as close to human skin as possibleIn experiments using mice, they analyzed these properties with various composite skinsThey used a xenogeneic acellular dermal matrix Dermal papilla cells were placed on this matrixIn the control group, DPCs were not used
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[13]
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Case Study: ICX‐SKN
3‐D Fibrin network
Seeded with fibroblast
Full thickness
Full integration with remolding of patient’s real skin
28 day cycle [8]
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Problems With All Grafts
Lack of Sensitivity
Wrong pigmentation
Hair growth/ sweat glands
Scarring
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Future
The replacement should not be a “replacement”
We need to better understand the skin
More complex tissue engineering
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References
1. Hansjor
Hauser, Martin Fussenegger, Artifical
Skin,
Tissue Engineering, Humana Press, 2007, pg 167‐1822.
Y. A. Kvistedal, P. M. F. Nielsen, Estimating
material parameters of human skin in vivo, Biomechanics and Modeling in Mechanobiology,
Springer, 20073.
Viktor Nedovic, Ronnie Willaert, Bioartificial
Skin ,
Application of Cell Immobilisation
Biotechnology, Springer, 2005, pg 55‐68
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References
4.
Ioannis
Yannas, Regeneration of Skin, Tissue and Organ Regeneration in Adults, Springer, 2001, pg 93‐
1375.
Paolo Santoni‐Rugiu, Philip J.Sykes, A History of
Plastic Surgery, Springer , 2007 pg 121‐1396.
http://nobelprize.org/nobel_prizes/medicine/laurea
tes/1960/medawar‐lecture.html
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References
7.
Masahiro Kino‐oka
, Masahito Taya, Development of Culture Techniques of Keratinocytes
for Skin
Graft Production, Advances in Biochemical Engineering/Biotechnology, Springer, vol
91, 2007,
pg 135‐1698.
Melody Boyd, Marzena
Flasza, Penny A Johnson,
John St Clair Roberts, Paul Kemp, Integration and persistence of an investigational human living skin equivalent (ICX‐SKN) in human surgical wounds,
Regenerative Medicine, vol
2, iss
4, pg 363‐370
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References
9.
John W. Skouge, Skin Grafting, The John Hopkins Medical Institutions, Churchhill
Livingstone, 1991
10.
Rudolph, Fisher, Ninnemann, Skin Grafting, Little, Brown and Company, 1979
11.
Roberto Rudge
Ramos, An easy and safe method of split‐thickness skin graft fixation, BurnsVolume
33,
Issue 8, , December 2007, Pages 1074‐1075.http://www.sciencedirect.com/science/article/B6T2
‐4PMJB5W‐2/2/d2d0809f129e19b2e213b55a1df89c4c)
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References
12.
Betul
Gozel
Ulusal, Ali Engin
Ulusal, Fu Chan Wei, Chun‐Yen Lin, Allograft Mass as a Possible
Contributing Factor to the Skin Transplant Outcome, Journal of Surgical ResearchIn
Press,
Uncorrected Proof, , Available online 13 June 2008.(http://www.sciencedirect.com/science/article/B6W
M6‐4SRM58V‐ 1/2/2c3ff7f28afab5db3edb7115786da2a9)
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References
14.
Shao‐Hai
Qi, Po Liu, Ju‐Lin Xie, Bin Shu, Ying‐Bin Xu, Chang‐Neng
Ke, Xu‐Sheng
Liu, Tian‐Zeng
Li,
Experimental study on repairing of nude mice skin defects with composite skin consisting of
xenogeneic
dermis and epidermal stem cells and hair follicle dermal papilla cells, BurnsVolume
34,
Issue 3, , May 2008, Pages 385‐392.(http://www.sciencedirect.com/science/article/B6T
52‐4PMT5WY‐ 1/2/cca37780421bcaab1bce883f3cc210c7)
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References
15.
British Journal of Dermatology, Volume 156, Issue 1 (p 165‐167)
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