What is an intracellular accumulation?
an accumulation of abnormal amounts of various substances
- manifestation of derangement in cells
what are the 3 categories of intracellular accumulations?
- normal cellular constituent in excess
- abnormal substance
- a pigment
what substances make up normal cellular intracellular accumulations?
too much water, lipid, protein, or carbohydrates
What is an exogenous abnormal substance?
mineral or products of infectious agents
What is an endogenous abnormal substance?
product of abnormal synthesis or metabolism
Where can intracellular accumulations occur?
cytoplasm or nucleus
how are substances in intracellular accumulations produced?
may be produced by the cells or may be storing products of pathologic processes
What are the 3 events that most accumulations are attributable to?
- a normal endogenous substance is produced at a normal or increased rate, but metabolism rate is inadequate to remove it
- a normal or abnormal endogenous substance accumulates bc of genetic or acquired defects in the metabolism, packaging, transport, or secretion of these substances
- an abnormal exogenous substance is deposited and accumulates bc the cell has neither enzyme to degrade it nor the ability to transport it to other sites.
what is are some examples of a normal endogenous substance that is produce at a normal or increased rate, but metabolism rate is inadequate to remove it?
- fatty change in liver bc of intracellular accumulations of triglycerides
- reabsorption protein droplets in the epithelial cells of renal proximal tubules bc of increased leakage of protein from the glomerulus
What are some examples of accumulations of abnormal or normal substances bc of genetic or aquired defects in metabolism, packaging, transport, or secretion of these substances?
- storage disease: A-GM1 gangliosidosis.
- Defient enzyme B-galactosidase in
holsteins, beagles, english springer
spaniels, siamese cats
- storage disease: b-GM2 gangliosidosis
- deficient enzyme hexosaminidase in
german shorthair pointer and
- c-Globoid cell leukodystrophy
- defient enzyme galactosylceramidase
in cairn terrier, min poo, blue tick
hound, beagle, pomeranian, polled
- B-a-1 antitrypsin deficiency
What is B-a-1 antitrypsin deficiency?
single amino acid substitutuion in the enzyme results in defects in protein folding and accumulation of the enzyme in the ER of the liver seen as globular eosinophilic inclusion bodies
What are some examples of an accumulation of an abnormal exogenous substance?
carbon particles and non metabolizable chemical like silica
What is anthracosis (pneumoconiosis)?
coal particle accumulation
If something is black, what are the 2 options it could be?
hemorrhage or melanoma
How do you differentiate between hemorrhage or melanoma?
check on white paper, hemorrhage will be red
If something is white, what are the differentials?
necrosis, abscess, or inflammation
In what types of cells are lipid accumulations most commonly observed?
hepatocytes and caradiomyocytes
- can also occur in skeletal muscle and kidney
What is lipidosis?
the accumulation of triglycerides and other lipid metabolites within the cytosol of the parenchymal cells
How are fat packaged?
What are some names for hepatic lipidosis?
fatty liver, fatty change, hepatic steatosis
how is fatty liver detected?
- alterations in liver function
- icterus or inc. liver enzymes
What does fat atrophy look like?
serous, gel-like substance in place of where fat was
- pale eosinophilic material histoloically
What causes serous atrophy of fat?
starvation or a metabolic negative energy balance
How does mitochondria injury affect fat metabolism?
decreases b-oxidation of fatty acids to ketones and other substances
What are some things that cause deceased apolipoprotein synthesis?
protein malnutrition, CCl4, aflatoxicosis
what causes lipolysis?
What is the order of nutrient breakdown during starvation?
glucose, fat, then protein
In ruminants, when is hepatic lipodosis a physiological process?
in late pregnancy (pregnancy toxemia) and heavy early lactosis (ketosis)
How are ketone bodies produced?
- produced in the liver by mitochondria
- conertin of acetyl CoA from fatty acids
what is a synonym for oxidation?
In what nutritional disorders can hepatic lipidosis be seen?
obesity, imparied apolipoprotein synthesis (protein malnutrition), starvation
What is Niemann Pick disease?
- causes hepatic lipidosis
- caused by lacking enzyme that breaks down sphyngomyelin (fatty substance)
- sphyngomyelin then accumulates in cells
how does diabetes mellitus cause hepatic lipidosis?
increases the mobilization of triglycerides
What is the cause of feline fatty liver syndrome and fat cow syndrome?
What is the prognosis of fatty liver in sheep?
In what types of cells is glycogen normally found/stored?
hepatocytes and myocytes
In what types of animals is glycogen found and stored in excessive amounts?
animals with abnormal glucose or glycogen metabolism:
- animals on corticosteroids
- animals with diabetes mellitus
It is normal to have high levels of glycogen in what animals?
What do you stain glycogen with?
What do you stain fat with?
In what cells is glycogen stored in animals with diabetes mellitus?
- hepatocytes, epithelial cell of renal proximal tubules, and B-cells of Islets of Langerhans
What are glycogenoses?
genetic disorder with enzymatic defects in the synthesis or breakdown of glycogen
What is type II?
- lysosomal metabolism defect
- deficient in the enzyme acid maltase
- seen in shorthorn and brahman beef cattle
- Laphund dog (pompe disease)
What is Type IV?
glycogen branching enzyme defect
- found in Norwegian forest cats
What is equine polysaccharide storage myopathy?
- excessive glycogen storage in skeletal muscle
- occurs in draft, warm blood, or quarter horses
What are the main muscles in which equine polysaccharide storage myopathy occurs?
Type II muscle fibers
-semimembranosus and semitendinosus
In equine polysaccharide storage myopathy, why does glycogen accumulate in type II muscle fibers?
- have high glycolytic capacity
- moderately fast contraction time and long term anaerobic activity
Besides glycogen, what also stains with PAS?
How do intracellular accumulations of proteins present?
- rounded eosinophilic droplets, vacuoles, and aggregates in cells
Which is more common, lipid or protein accumulation?
what are the 2 causes for protein accumulations in cells?
- excesses are presented to the cells
- cells synthesize excessive amounts
How do protein reabsorption droplets in renal proximal tubule cells present?
- hyaline, pink/ eosinophilic cytoplasmic droplets
- they have a granular appearance
When do reabsorption droplets in the proximal tubule cells of the kidney occur?
occurs during heavy protein leakage across the glomerular filter
What are russell bodies?
excessive production of normal protein that form grape-like hyaline bodies
Where are russell bodies normally found?
in the cytoplasm of some plasma cells= mott cells
When do you see large amounts of mott cells?
in sever inflammatory responses or plasma cell tumors
normally, what happens if there is a defect in protein folding?
the protein is eliminated by the proteasome complex
What occurs in Alzheimers disease?
intracellular accumulation of tau protein
What are viral inclusion bodies?
accumulations of viral protein
- can be DNA or RNA viruses
What DNA viruses form intranuclear inclusion bodies?
herpes, adeno, and parvo
What viruses form intracytoplasmic inclusion bodies?
What RNA viruses form intracytoplasmic inclusion bodies?
In rabies, what is the main location of infection in carnivores?
In rabies what is the main location of infection in the horse?
spinal cord and brainstem
What RNA virus forms intracytoplasmic and intranuclear inculsion bodies?
How do viral incusion bodies present?
- round to oval
- eosinophilic (herpes)
- basophilic (adeno)
What are lead inclusion bodies?
- lead and protein
- present in renal tubular epithelial cells
What do you stain lead inclusion bodies with?
What does hyaline mean?
- descriptive term
- glassy, eosinophilic, translucent in H&E
What are some hyaline substances?
- renal tubules in proteinuria
- serum or plasma
- plasma proteins in vessel walls
- scars/ collagen fibers
- thickened basement membranes
- membrane of alveolar walls
- microthrombi in DIC
What is the appearance of renal tubule cells in proteinuria?
cells are flat and undergoing necrosis
What is amyloidosis?
condition associated with a number of inherited and inflammatory disorders in which extracellular deposits of fibrillar proteins are responsible for tissue damage and functional compromise
What are abnormal fibrils?
produced by aggregation of misfolded proteins and have beta-pleated sheet conformation
What is systemic amyloidosis?
involves components of the immune system
- probably related to abnormal protein folding and immunological abnormalities
What are the 2 types of proteins that form amyloid?
normal proteins and mutant proteinse
How is amyloidosis caused by normal proteins?
they are normal proteins that have an inherent tendency to fold improperly, associate and for fibrils, and do so when they are produced in increased amounts
How do mutant proteins cause amyloidosis?
they are prone to misfolding and subsequent aggregation
What is primary amyloidosis?
- Ig-light chain
- plasma cell proliferation
- uncommon in animals, common in humans
what is secondary amyloidosis?
- AA amyloid
- occurs in chronic inflammatory responses, presistant infections, or neoplastic conditions
- most common in animals
In what animals is amyloidosis most common?
- black-footed cat and cheetahs
- older dogs (idiopathic)
In old dogs, where does amyloidosis predominantly occur?
around the blood vessels in the heart and the brain
- no clinical signs
Where is amyloid deposited in the kidney?
- medulla in cats
What are the 3 main organs in which amyloid is deposited in?
kidney, liver, and spleen
where is amyloid deposited in the liver?
space of disse in cattle, horses, dogs, cat and ducks
Where is amyloid deposited in the spleen?
what is special when staining amyloid with congo red?
must use polarized light to prove it is amyloid
How does amyloid appear grossly when it is stained with Lugol's iodine and enhanced with dilute sulfuric acid?
How does amyloidosis of the liver in cattle vs. other animals?
it is firm instead of friable
What is gout?
deposition of sodium urate crystals or urates in tissue
- seen in birds and reptiles
What are some causes of gout?
- vit A deficiency, high protein diets, and renal injury
What is the most common site for gout in birds?
commonly covering the heart
How do you fix tissue to see urates?
fix in alcohol
Are urates deposited extracellularly or intracellularly?
What are cholesterol crystals?
by-products of hemorrhage and necrosis
What is anherosclerosis?
thickened arterial intimal
What do cholesterol crystals form?
Where do cholesterol granulomas form in horses?
- in choroid plexus
- cause obstruction of outflow of CSF
- can lead to hydrocephalus