Extracellular Pathology

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Extracellular Pathology

• Amyloidosis
• Pathological calcification
• Ageing

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Amyloid and Amyloidosis

• A Set of Disorders The main feature is the
  extracellular deposition of proteins arranged in
  the form of a Beta-pleated sheet
• Amylum Latin for starch
• Term first used By Virchow in 1854
• Protein.Friedreich and Kekule. 5 years later

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Amyloidosis

• Amyloidosis is a clinical disorder caused by
  extracellular deposition of insoluble abnormal
  fibrils that injure tissue.
• The fibrils are formed by the aggregation of
  misfolded, normally soluble proteins.
• In humans, about 23 different unrelated proteins
  are known to form amyloid fibrils.

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Amyloidosis

• All types of amyloid consist of a major fibrillar
  protein that defines the type of amyloid
  (approximately 90) plus various minor
  components.
• Although each type of fibril may be associated
  with a distinct clinical picture, all share
  certain physical and pathologic properties

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• Organs affected by amyloid
• Larger, Paler, Firmer
• How do we identify Amyloid in tissues?
• Macroscopically (Grossly)
• Waxy, Sharper cut edges, Lugols iodine (black).
• Microscopically
• Light Microscopy-
• Amyloid is eosinophilic and stains with Congo Red
• Polarized light Apple Green Birefringence.
• Electron Microscopy Rigid non branching fibrils
  (7.5 nm to 10 nm in diameter)

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Kidney
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Heart, Lugols iodine
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HE Stain
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Congo Red Stain.
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Apple Green Birefringence
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Electron Microscope
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• The Beta- Pleated sheet is the unifying feature
  of the amyloidoses
• Basis of 1) Congo Red reaction
• 2) Fibrillar ultrastructure
• 3) Resistance to proteolytic
• digestion

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Why?

• Protein Misfolding
• Intrinsic tendency to misfold (Transthyretin)
• Misfolding and aggregation at high concentration
  (Beta Microglobulin)
• Point mutations (Hereditary amyloidosis)
• Review Molecular mechanisms of amyloidosis.
  Merlini G, Bellotti V. NEJM August 2003
  349583-96

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Classification

• Older classifications 1 and 2
• More useful to classify on the basis of
• 1) Nature of protein involved
• 2) Anatomical distribution
• 3) Inherited or acquired

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Acquired Systemic Amyloidosis

• 1) Amyloidosis of immune origin. AL type
• Acquired, Systemic form
• Protein precursor is usually immunoglobulin light
  chain.
• Occurs in association with a monoclonal (i.e.
  neoplastic) proliferation of B lymphocytes or
  plasma cells e.g.
• Myeloma (Lambda chains)
• Waldenstroms macroglobulinaemia (LPL)

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• AL amyloid proteins Intact immunoglobulin light
  chain or the amino terminal fragment of a chain
  or both. (mostly lambda chains)
• 90 of these patients have Bence Jones proteins
• Amyloid accumulation Two step process
• 1) Secretion of excess amounts of monoclonal
  light chain
• 2) Conversion to Beta pleated form.

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Clinical features

• Middle to old age
• MgtF
• 90 have a Bence Jones protein
• Bone marrow excess plasma cells
• Manifestations
• Neuropathy, Restrictive Cardiomyopathy, Skin
  manifestations, Polyarthropathy, Macroglossia,
  Carpal Tunnel Syndrome
• (Heart, CNS, Joints, Skin, Tongue, Soft Tissues)

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Immunofluorescence microscopy with antibody to
the lambda light chain.
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Cardiac
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Acquired Systemic Amyloidosis

• 2) Haemodialysis associated Amyloid
• Acquired, systemic
• Protein is Beta-2-microglobulin.
• Normally broken down by kidneys
• A naturally occurring amyloidogenic protein not
  filtered by dialysis membranes
• After 7 years on dialysis 30 of patients get
  Carpal Tunnel Syndrome (after 10 years 50)
• Joints, synovium, tendon sheaths

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Acquired Systemic Amyloidosis

• 3) Reactive Systemic Amyloidosis
• Also known as secondary amyloid or AA type
  amyloid
• Acquired, systemic form
• Protein precursor is serum amyloid A (SAA)
• Acute phase reactant which markedly increases
  with tissue injury or inflammation under the
  influence of IL1, TNF and IL-6
• AA is a cleavage product of SAA.
• Distribution of amyloid kidney, liver, spleen,
  adrenals, thyroid many other tissues.
• Diagnosis Rectal Biopsy

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Disease Associations

• 1) Chronic infection T.B., Leprosy, Syphilis,
  Chronic osteomyelitis, Bronchiectasis
• 2) Chronic inflammation
• Reiters disease, Whipples disease
• 3) Chronic autoimmune disease
• R.A., I.B.D., Connective Tissue Disease
• 4) Long standing paraplegia. (UTI)
• 5) Neoplasms
• Renal adenocarcinoma and Hodgkins disease

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Liver
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Adrenal
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Hereditary Systemic Amyloidosis

• Rare.
• Most common Familial Mediterranean Fever.
• Less common Three types
• Neuropathic.
• Cardiopathic.
• 3) Nephropathic.
• The Amyloid protein is usually Transthyretin
  (Prealbumin). Transthyretin is also associated
  with a form of Amyloid known as Systemic Senile
  Amyloid, where amyloid is systemically deposited,
  mainly in the heart in elderly individuals.

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• Familial Mediterranean Fever
• Commonest form of hereditary systemic amyloidosis
• Autosomal Recessive, Gene on Chromosome 16
• AA type amyloid
• Two manifestations of the disease
• Short febrile attacks with pain mimicking
  pleurisy, peritonitis or
• synovitis
• Amyloidosis Manifest early in life
• Death before 40 without Renal Transplant
• Treated with Colchicine (Stabilization of
  inflammatory cells)

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Localized amyloidosis

• Endocrine associated
• Pituitary - age related
• Islets of Langerhans - NIDDM related
• Medullary Carcinoma of Thyroid (Calcitonin)
• Intacerebral
• Alzheimers, Spongiform Encephalopathy

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Islets
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Amyloid angiopathy
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Alzheimers disease
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Medullary Thyroid Carcinoma
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Pathological Calcification

• Dystrophic Calcification
• Metastatic Calcification
• Idiopathic Calcification

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Dystrophic Calcification

• Normal serum calcium/phosphate
• Nonviable or dying tissues
• Occurs in atherosclerosis, damaged valves,
  necrosis (coagulative, caseous, liquefactive),
  Leiomyomas
• Monckebergs medial sclerosis
• Intracellular / Extracellular
• Two phases Initiation and Propagation

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Dystrophic Calcification
Tricuspid valve
Stomach
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Metastatic Calcification

• Must be associated with elevated Calcium.
• Occurs in vital tissues
• Aetiology
• Increased PTH
• Hyperparathyroidism
• Bone destruction
• Tumour (MM, Leukaemia), Skeletal Mets (Breast
  Ca.)
• Increased bone turnover (Pagets),
  Immobilisation.
• Vitamin D related disorders
• Excess Vitamin D
• Sarcoidosis
• Renal Failure
• Retention of Phosphate, (secondary HyperPTH)

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Metastatic Calcification

• Kidney Around tubules - Renal Failure.
• Lung Alveolar walls.
• Stomach Fundal glands.
• Identification of Calcium
• Von Kossa

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Hyperparathyroidism

• Primary, Secondary, Tertiary
• 1 Increased bone re-absorbtion and
  mobilization of calcium from bone
• Increased renal tubule re-absorption.
• Increased Vit. D activity
• Bones, stones , (psychic moans) and abdominal
  groans

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• Aetiology
• 1) Parathyroid adenoma. 75
• 2) Hyperplasia. 10-15
• 3) Parathyroid carcinoma lt5
• (MEN 1 or MEN2a)
• Secondary Renal Failure, Osteomalacia.

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Ageing

• Aging is NOT a disease
• The changes that occur with aging make aged
  persons more susceptible to disease
• Aging is probably multifactorial involving both
  internal (Genetically programmed) and external
  (Tissue damage) factors that combine to exert
  their effects

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• Theories of Aging
• Cellular Changes.
• There is cumulative free radical damage to DNA
  and to proteins (perhaps due to lack of
  antioxidants).
• Genetics
• Another theory suggests that aging is determined
  by genetic programming and malfunction.
• 1962 The Hayflick phenomenon. Telomeres and
  Telomerase
• Progeria (Werners syndrome). DNA Helicase
• Loss of Homeostasis
• Environmental Stress
• Neuroendocrine Dysfunction
• Nutrition

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Organ Systems

• Central Nervous System
• Stroke.
• Alzheimers.
• Neuronal loss.
• Eye
• Cataracts.
• Presbyopia.
• Ear
• Presbycusis.

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• Cardiovascular System
• Atheroma
• Calcification (Senile calcific aortic sclerosis)
• Senile Amyloid.
• Urinary Tract
• Decreased GFR.
• Increased UTI in women.
• Musculoskeletal System
• Decreased bone mass.
• Osteoarthritis.

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• Genital Tract
• Menopause leads to atrophy of ovaries, uterus,
  and breasts. The epithelium of the vagina and
  vulva also become thinner.
• Prostatic Hyperplasia.
• Skin
• Decreased elasticity.
• Senile lentigines

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Telomere
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Timing of Aging Telomeres

• Telomerase stabilizes telomere lengths
• Active in germ cells, absent in most somatic
  cells
• May be reactivated in cancer cells
• When cells replicate, small portion of telomere
  not duplicated
• Telomere shortening growth checkpoint signal
  for cell to become senescent
• Mechanism for cells to count their divisions

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Genetic Damage and Aging Werners Syndrome
DNA helicases are known to be involved in the
repair, replication and expression of the genetic
material. Defects in DNA helicase lead to
premature aging Rapid accumulation of genetic
damage, mimicking the aging process Premature
aging also seen in Cockayne syndrome and ataxia
telangiectasia, other inherited defects in DNA
repair.
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Summary

• Ageing
• Effects a combination of
• Intrinsic factors telomere lengths
• Extrinsic factors progressive DNA (and other
  cellular) damage
• The latter may be accelerated by inherited
  defects in DNA repair.

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Summary

• Amyloid.
• Appearance / identification
• Types of acquired and inherited amyloidosis
• Pathological calcification.
• Dystrophic / Metastatic / Idiopathic
• Causes and Consequences
• Ageing
• Theories of Aging