Download Proteoglycans

Connective Tissue
Course : Microanatomy (SCAN 213)
For : Pre-medical students II
Time : 2 h
Date : October 31,2001
Lecturer: Dr. Prapee Sretarugsa
Department of Anatomy
Faculty Of Science
Mahidol University
Tel : 201- 5424
E-mail : [email protected]
Dr. Prapee
1
Objectives
: After you have studied this lecture, you should be
able to
• Explain the components of connective tissue
• Describe the structures and functions of all types
of cells in connective tissue
• Identify all fibers in connective tissue as well as
their localization in the organs
• Explain the composition of ground substance as
well as its function
• Classify the type of connective tissue
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Connective Tissue (CT)
• Derives from mesoderm
• Mesenchyme pleuripotency)
• Mesenchymal cells can differentiate into
- connective tissue
- bone, cartilage
- blood and hemopoietic cells
- lymphoid cells
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Characteristic of Connective Tissue
• Consists of a large amount of
extracellular matrix with a limited
number of cells
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Extracellular Matrix (ECM)
• A complex of nonliving macromolecules
synthesized by the cells
• Some tissue consists of small amount of ECM
• Connective tissue contains a large amount of
ECM with a limited number of cells
• A major component of connective tissue
proper
• Comprises of
- Ground substance – resists forces of
compression
- Fibers – provides tensile force
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Ground Substance
Consists of
• Glycosaminoglycans (GAGs)
• Proteoglycans
• Adhesive glycoproteins
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Properties of GAGs
• Long, inflexible, unbranched polysaccharides
• High negative charge
• Repeating disaccharide units
• One of repeating unit is amino sugar which
is sulfated (SO-3)
• Second sugar is uronic acid with a carboxyl
gr. (COO-)
• Retension of positive ions (eg. Na+) together
with water, maintaining tissue architecture
turgor which tend to prevent deformation by
compressive force
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Structure of GAGs
- Disaccharide units
form covalent linkage
with protein to form
proteoglycans
- Proteoglycans attach
to hyaluronic acid
- Hyaluronic acid,
nonsulfated GAG
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Types of GAGs
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Struture ofProteoglycan
•Macromolecues
formed by sulfated
GAGs form covalent
bonds with a protein
core
• Structures look
like a bottle brush
• linked to
•Each proteoglycan is covalently
hyaluronic acid forming huge macromolecules,
Aggrecan aggregates
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Proteoglycans
•Macromolecues formed by sulfated GAGs form
covalent bonds with a protein core
• Structures look like a bottle brush
• Each proteoglycan is covalently linked to
hyaluronic acid forming huge macromolecules,
Aggrecan aggregates
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Functions of Proteoglycans
• Resist compression and retard the rapid
movement of microorgani and metastatic
cells
• Form molecular filter (in association with
basal lamina) of varying pore sizes and
charge distributions that selectively screen
and retard macromolecules as they pass
through them
• Contain binding sites of certain signaling
molecules eg. TGF-ß
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Functions of Proteoglycans and
Hyaluronan during development
• Epithelial branching and differentiation
• Eye development
• Limb development
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Adhesive Glycoproteins
Large macromolecules have several domains
- at least one domain usually bind to
integrins
- one to collagen fibers
- one to proteoglycans
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The Major Types of Adhesive
Glycoproteins
•
•
•
•
•
•
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Fibronectin
Laminin
Entactin
Tenascin
Chrondronectin
Osteonectin
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The Binding Sites of Adhesive
Glycoproteins
Fibronectin - collagen, heparin, heparan sulfate,
hyaluronic acid, integrin
Laminin
- stricly limited to the basal lamina
- heparan sulfate, type IV collagen,
entactin & cell membrane
Entactin - laminin, type IV collagen
Tenascin - integrin, proteoglycan & fibronectin
- distribution is limited to embryonic
tissue
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The Binding Sites of Adhesive
Glycoproteins
Chrondonectin
- type II collagen, chrondroitin sulfate,
hyaluronic acid, & integrins of chondroblast
and chrondocyte
Osteonectin
- type I collagen, integrins of osteoblast and
osteocyte
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Integrin
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Fibers
• Provide tensile strength and elasticity to ECM
• Can be classified into 3 types based on their
morphology and reactivity with dyes
- Collagen
- Reticular
- Elastic
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Collagen Fibers
• Collagen, constitue about 20% of all the body
proteins
• Form a flexible fiber whose tensile strength
is greater than that of stainless steel of
comparable diameter
• White fiber, colorless
• No specific staining for collagen fiber
• Acidophilic fiber
• EM showing cross-banding at regular interval of
67Dr.nm
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Components of collagen fibers
• Smaller subunits,
tropocollagen
•Formed from parallel
aggregates the thinner
fibril 10 to 300 nm in
diameter
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Tropocollagen
• 280 nm long
• 1.5 nm in diameter
• Three polypeptide chains, a-chains
- formed triple helical configuration
- each chain contains about 1,000 aa
- every third aa is glycine
- the majority of the remaining aa is
proline, hydroxyproline,hydroxylysine
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Six Major types of collagen
Types
I
II
III
Characteristics
Most common type collagen ,thick
fiber
Forms slender fiber in hyalin and elastic
cartilages
Reticular fiber
- Highly glycosylated, thin fiber0.5-2.0 um
- Rich coating of sugar likely stained with
silver salt (Argyrophilic fiber)
- positively stained with periodic acid schiff (PAS) reaction
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Six Major types of collagen
Types
IV
V
VI
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Characteristics
Do not display 67 nm periodicity
Forms a meshwork of procollagen
molecules
Forms very thin fibrils and association
with Type I
Forms small aggregates, anchoring fibrils
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Elastic Fibers
• Slender, long and branching in loose CT
• Form coarse bundles in ligament
(ligamentum flavum) and fenestrated sheet
(concentric sheet in the wall of large a.)
• Elastin,a protein rich in glycine and proline
- unusual aa, Desmosine & Isodesmosine
- a high degree of elasticity
- forms a core of elastic fiber
• Microfibrils (10 nm in diameter, glycoprotein,
fibrillin), located at the periphery of elastin
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Elastic fibers
Dr. Prapee
A. Elastin has a random coil
structure in the relax state,
but reforms as a different
random coil on relaxation
B. Elastin molecule are
covalently linked into arrays
which can reversibly stretch
and recoil, and may be
arranged as fibers or sheets
• Elastic fibers are composed of
microfilaments surrounding and
organizing core region of crosslinked elastin
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Blood vessel, showing the elastic fibers
Elastic f.
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Tunica media of aorta
Show
the
typical
wavy
appearance
of
thick
bundles
of
elastic
fiber
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Reticular fibers
• Collagen type III
• Frame work of lymphoid
organs, liver ect.
• Highly glycosylated, thin
fiber0.5-2.0 um
• Rich coating of sugar
likely stained with silver salt
(Argyrophilic fiber)
• Positively stained with
periodic acid - schiff (PAS)
reaction
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Cellular components of CT
• Fixed cells
- A resident population of cells have developed
and remain within CT
- fibrobasts, mast cells, adipose cells, pericytes
& macrophages
• Wandering (Transeint) cells
- Originate mostly in bone marrow
- plasma cells, lymphoctes, neutrophils,
eosinophils, basophils, monocytes, and some
macrophages
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Fibroblasts
- Produce ECM & Fibers
- Active fibroblasts often reside with collagen
bundles
- Elongated, fusiform cells & pale-staining
cytoplasm
- Large ovoid nuclei with prominent nucleoli
- EM, showing prominent RER, Golgi complex
- Inactive, Fibrocytes ; small, elongate & deeply
stained nuclei
- Some movement
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Fibroblasts and Fibrocytes
Fibroblasts
Fibrocytes
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Fibroblasts, showing euchromatic nucleus,
prominent RER
Collagen fibers
Collagen fibers
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RER
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Myofibroblasts
- Modified fibroblasts contain actin and myosin
filaments
- Surface profile of nucleus resembles smooth m.
- Basal lamina is absent
- Abundant in wound healing area (purse string
effect)
- Contribute to retraction and shrinkage of scar
tissue
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SEM : Pericytes
- Undifferentiated mesenchymal cells
- As named adventitial cells or perivascular cells
- Locate around capillaries and venules
- Possess
Dr. Prapeecharacteristic of smooth muscle cells and endothelial
36cells
TEM : Pericytes
Capillary
Pericyte
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- Their basal lamina are
directly continuous
with basal lamina of
endothelial cell
- EM, cytoplasmic
characteristics almost
identical with
endothelial cells
- In large venules, they
have characteristic of
smooth m.
cells
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Wound healing
- New connective tissue & blood vessels are formed
- Undifferentiated mesenchymes lacated in tunica
adventitia of venules and small veins
- Fibroblast
- Pericytes
- Endothelial cells
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Macrophages
- They function in removing cellular debris (phagocytosis)
and protceting body against foreign invaders
- They also play a role in presenting antigens to
lymphocytes
- They are about 10-30 um in diameter
- Cell surface is uneven
- Basophilic cytoplasm, many small vacuoles, small dense
granules- Indented nucleus
- EM showing prominent Golgi app. & RER, abundant
lysosomes
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Macrophage
Under chronic inflammatory condition
• They congregate, enlarge and become
polygonal-shaped epitheloid cells
• If the particulate matter is excessive large,
several macrophages may fuse to form a Foreignbody giant cell
• Macrophage residing in CT, Fixed Macrophage
(resident Macrophage)
• Free Macrophage - migrate from the blood
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Macrophage
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Macrophage Development and
Distribution
• Histologist once believed that macrophages
were derived from precursor cells in
Reticuloendothelial System, which included
nonphagocytic cells
• Presently, all members of phagocytotic cells
arise from a common stem cell in bone marrow,
possess lysosomes, can phagocytose and display
Fc receptors and receptors for complement, as
classified to as Mononuclear Phagocyte System
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Macrophage Development and
Distribution
Macrophages localized in certain regions of the
body were given specific names before their origin
was understood.
• Kupffer cells of the liver
• Dust cells of the lung
• Langerhans cells of the skin
• Monocytes of the blood
• Macrophages of CT, spleen, lymph node, thymus
and bone marrow
• Osteoclast of the bone
• Microglia of the brain
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Mast cells
• Oval shape with round or oval nucleus
• 20-30 um in diameter
• Abundance of the large basophilic granule
• Granules show Metachromasia
• Granules containing histamine, heparin,
eosinophil
chemotactic factor (ECF), nutrophil
chemotactic factor (NCF), chondroitin sulfate
protease, aryl sulfatase
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Mast cells
• Oval shape with round
or oval nucleus
• 20-30 um in diameter
• Abundance of the
large basophilic granule
• Granules show
Metachromasia
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Mast cells
Dr. Prapee• Granules show
Metachromasia
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Mast Cell
• Granules containing
histamine, heparin,
eosinophil
chemotactic factor
(ECF), nutrophil
chemotactic factor
(NCF), chondroitin
sulfate protease, aryl
sulfatase
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Plasma cells
• Found in large numbers in area of chronic
inflammation
• Derived from B lymphocyte
• Ovoid cells, 10-20 um, eccentric nucleus
• Short life span of 2-3 weeks
• Intensely basophilic cytoplasm, prominent RER
• Spherical nucleus consisted of heterochromatin
radiating out from the center, look like
clockface appearance in LM observation
• Produce circulating antibodies (r-globulin)
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Plasma cells
• Found in large numbers in area of chronic inflammation
• Derived from B lymphocyte
•Dr.Ovoid
Prapee cells, 10-20 um in diameter, Eccentric nucleus
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Plasma Cell
• Intensely
basophilic
cytoplasm,
prominent RER
• Produce
circulating
antibodies (rglobulin)
• Spherical nucleus consisted of heterochromatin
radiating out from the center, look like
clockface
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Lymphocyte
• Smallest free cells, 6-8 um in
diameter
• Spherical with round nucleus
(heterochromatin)
• Thin rim of cytoplasm
lym
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Lymphocyte
• EM, a few organelles
but a large number of free
ribosome
• Thin rim of cytoplasm
• Small, medium & large
lymphocytes
• B-Lymphocytes
plasma cells
• T-Lymphocytes
cellmediated immunity
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Lymphocyte
• Accumulate in Peyer's
path of Ileum
• Distribute in lamina
propria of G.I &
respiratory tract etc.
Lamina propria
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Neutrophils
Dr. Prapee
- Polymorphonuclear
neutrophil (PMN),
polymorph, 4-5 lobes
- 10-12 um in diameter
- There are three type of
granules
- Small, specific
granules (alkaline
phosphatse)
- Large, azurophilic
granules, lysosomes
(peroxidase, acid
phosphatase)
- Tertiary granules
(gelatinase, cathepsins)
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Neutrophils
- The first cells to appear in acute
bacterial infection
- Phagocytose microorgansim
die
resulting in formation of pus
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Neutrophil
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Eosinophils
•10-12 um in diameter
•Bilobes nucleus
• Large elongated granules
- crystalloid body
- peroxidase
- histamine
- hydrolytic enzyme
• Phagocytose Ag-Ab
complex
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Eosinophils
Note : the crystalloid bodies in the granules
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Monocyte
In blood
CT
Macrophage
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Basophil
• Bilobed nucleus
• Smaller size than
monocyte
• Contains receptor
for immunoglobulin
as in mast cell
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Adipose Tissue
• Unilocular adipose tissue, White fat
• Multiloccular adipose tissue, Brown fat
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Adipose cells
White fat
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• Adipocytes, Adipose cells,
Lipoblasts
• Single lipid droplet
• Variation in color from
white to deep yellow,
depend on carotenoid in diet
• Eccentric nucleus, signet
ring appearance
• Lipid is usually extracted
during conventional
preparation
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White Fat : Sudan red
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• A few organelles
• Mature adipocytes do not
divide
• Highly blood supply
• Receptors for Insulin, GH,
NEP, Glucocorticoid
• Distribute in subcutaneous
layers, mesentery
• Accumulation depends on
sex, age, region
• Large cells, 100-120 um,
thin rim cytoplasm
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Brown Fat
Dr. Prapee
• Multiple lipid droplets
• Tan to reddish brown,
cytochrome in mitochondria
• Eccentric round nucleus
Extensive vascularity
• Numerous unmyelinated
nerve fiber, axon ending on
both blood vessels and on fat
cells
• Prominent in newborn
• Rate of fatty acids
oxidation up to 20 times the
rate of white fat
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Brown Fat
• A few cell
organelles
• Abundant roundshaped
mitochondria
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Distribution of Brown Fat
New
born : superficial
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Prapee
Deep
Rabbit
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Clinical correlations : Adult, obesity
• Hypertrophic obesity
- accumulation and storage of fat in
unilocular fat cells
- increase their size
• Hypercellular obesity
- over abundance of adipocytes
- this type of obesity is severe
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Clinical Correlations
• Lipomas, common benign tumor of
adipocytes
• Liposarcomas, malignant tumors of
adipocytes
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Mesenchymal CT
• Numerous mesenchymal
cells, oval euchromatic
nucleus, prominent nucleoli
• Pluripotency
• Pale-staining cytoplasm,
small processes
• Gel-like, amorphous
ground substance
• Consists of reticular
fibers
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Mucous tissue
• Fibroblasts
• Jelly-like, amorphous ground
substance composed of
hyaluronic acid called
Wharton's jelly
• Composed of Type I and type
III collagen fibers
• Found in umbilical cord,
subdermal C T of embryo
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Connective Tissue Proper
Loose (Areolar) C.T.
• Abundant ground substance, proteoglycans
• Contains all types of cells
• Contains all types of fibers
• Fills in the body spaces, adventisia of blood
vessels, lamina propria of G.I. tract ect.
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Loose Connective Tissue displaying
collagen (C) and elastic fibers
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Distribution of
loose CT in lamina
propria of GI
tract
Lamina propria
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Dense C T
• More fibers
• Fewer cells
• Orientation and
arrangements of the fiber
make it resistance to stress
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Dense Irregular C T
• Mostly coarse collagen fibers arranged
randomly that resists stress from all
directions
• Fibroblast, the most abundant cells
• Distribution in dermis, sheath of
nerves, capsule of organs ect.
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Dense irregular CT : Perichondrium (P)
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Dense irregular CT: Dermis
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Dense Regular
Collagenous C T
• Collagen bundles densely packed and
oriented into parallel cylinders or sheet
• Resists tensile strength
• Little ground substance and cells
(Fibroblasts)
•Tendons, ligaments, aponeuroses
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Dense Regular Collagenous C T
( Tendon )
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Dense Collagenous Connective Tissue
(Muscle- tendon junction)
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Dense Regular Elastic C T
• Elastic fibers arranged parallel to
each other and form thin sheets or
fenestrated membrane (large bl.ves.)
• Ligamentum flava of vertebral
column, suspensory ligament of penis
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Reticular Tissue
• Type III collagen
• Form mesh-like
network
• Liver sinusoid, adipose
tissue, lymphoid organs
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