Pigments and Lipids Flashcards
State the three types of pigment
Artefact
Endogenous (haematogenous/autogenous)
Exogenus
Define Artefact pigment
Deposits produced as a result of chemical reaction in tissue
Define Endogenous tissue
Produced within tissue
Have a physiological function or are a by-product of normal metabolic process
Define exogenous tissue
Gain access to the body accidentally
No physiological function
Usually minerals, enter by inhalation or implantation on skin (during industrial exposure)
Give examples of Artefact pigment
Formalin
Malarial
Mercury
Dichromate deposits
Give examples of endogenous pigments
Bile pigments
Lipofuscin
Melanin
Iron
Calcium
Copper
Uric acid and urates
Give three examples of conditions formed as a result of bile pigment accumulation
Obstructive/surgical Jaundice
Primary biliary cholangitis (PBC)
Cholestasis
Outline obstructive jaundice
- A symptom of an underlying condition (involving the liver, gallbladder, or pancreas)
- Usually requires surgical intervention
- Accumulation of bile pigments
- Injury to bile duct/obstruction of bile flow
- Can cause hepatocellular damage and cirrhosis (eventually)
Outline PBC
- Autoimmune disease of liver
- Results from a slow, progressive destruction of the small liver bile ducts, causing bile/other toxins to build up in liver
Outline cholestasis
- A liver disease
- Bile cannot flow from liver to duodenum
- Obstructive: mechanical blockage in duct system due to gallstone or malignancy
- Metabolic: disturbances in bile formation due to genetic defects or medication
Outline Haemosiderin
- Iron-storage complex in cells/tissues (not in blood circulation)
- Iron derived mainly from breakdown of erythrocytes (RBCs)
- Poorly available to supply iron when needed
Outline Perls Prussian blue staining (ferric iron - Fe3+)
- Protocol chemicals: dilute hydrochloric acid (releasing ferric ions from binding proteins by partial denaturation of protein), potassium ferrocyanide
- Method stains mostly iron in ferric state, including ferritin and haemosiderin
How does Perls Prussian blue staining work?
- Potassium ferrocyanide combines with ferric iron, forming prussian blue pigment (aka ferric ferrocyanide)
- Addition of hydrochloric acid increases iron availability within tissue
What colour does Formalin pigment stain?
Brown/Black (once fixated in acid formalin)
Where is formalin pigment often found?
Haemorrhagic tisdue
What colour does malarial pigment stain?
Brown/black
How to differentiate between formalin and malarial pigment?
Malarial pigment is found in RBCs with parasite
What colour does mercury pigment stain?
Black
What colour do dichromate deposits stain?
Yellow/brown
Outline bile pigments
- Red/brown = bilirubin
- Green = biliverdin
- Result of RBCs breaking down
- Buildup suggests liver/haemolytic disease
Outline Lipofuscin
- Brown
- ‘Wear and tear’
- Due to lipid oxidation near nucleus
- Found in the heart, liver, brain
Outline melanin
- Black/brown
- Product of melanocytes
- Found in eye/skin/hair/brain/melanoma
- Dyed by Masson Fontana (black)
Outline Iron
- Fine brown colour
- Blue after Prussian Blue reaction
- Stored as haemosiderin in ferric state (Fe3+)
- Found in liver, spleen, bone marrow
State 3 iron store disorders
- Haemosiderin
- Haemosiderosis
- Haemochromatosis
Outline Haemochromatosis
- Inherited condition
- Iron levels slowly build up over many years
- Symptoms: skin bronzing, fatigue, diabetes, cirrhosis
- Ages 40-60/post menopause
- Requires phlebotomy treatment
Outline Haemosiderosis
- AKA secondary haemochromatosis
- Acquired and less toxic than primary
- Iron predominantly stored in reticuloendothelial system
- Treated with iron chelating agents
Outline Haemosiderin
- A symptom of a iron disorder
- Too much can cause organ failure
Outline calcium
- Stained black(?)
- Absorbed via GIT (vit D)
- Stained by von Kossa and Alizarin
- Found in teeth/bone
Outline copper
- Normally undetectable
- An accumulation causes Wilson’s disease
- Specific stains required
Outline Uric acid and urstes
- Use a polarising microscope, birefringent
- Breakdown of purine nucleotides
- High amounts can lead to joint crystallisation (gout), kidney diseases, diabetes
Give examples of Exogenous pigments
Carbon
Silica
Asbestos
Outline Carbon
- Most common exogenous pigment
- Easily identified
- Confused with melanin
- Seen in lungs of smokers
- Absorbed by phagocytes
How to differentiate carbon and melanin?
Melanin bleach
Outline Silica
- Intert angular masses
- Same material as glass
- In lungs (causes silicosis /fibrosis of lungs)
- May be birefringent
Outline Asbestos
- Long beaded fibres
- Causes fibrosis
- May lead to asbestosis and mesothelioma
- Fibres become coated in protein sheaths containing haemosiderin (demonstrated by Prussian Blue)
List unconjugated lipids
Neutral fats
Waves
Cholesterol esters
Phosphoglycerides
Sphingomyelins
Ceramides
Glycolipids
List conjugated lipids
Fatty acids
Steroids
Define a lipid
Soluble in fat solvents BUT insoluble in water. They are hydrophobic.
How to view lipids:
- Lysochrome method (staining using a dye very soluble in lipids, insoluble in aqueous solution)
- Frozen, stained by Oil Red O or Sudan Black
- Use of polarised light microscope (view oval fat bodies)
- Osmium Tetroxide fixation (view the lipids as black)
Briefly outline lipid storage disorders:
- AKA Lipidosis
- a group of inherited metabolic disorders in which harmful amounts of fatty materials (lipids) accumulate in various cells and tissues
- Particularly accumulate in CNS
Give an example of a lipid storage disorder
Fabry disease (accumulation in kidney)
