[B] 1.26 Disturbances in carbohydrate metabolism

Question 1

Examples of disturbances of carbohydrate metabolism

Answer 1

• Glycogen detection in tissues
• Depletion of glycogen in tissues
• Accumulation of glycogen in tissues
• Pathology of DM

Question 2

Glycogen detection in tissues

Answer 2

Amount of glycogen detected

• Original concentration
• Time between death and fixation
  *

Question 3

Glycogen detection in tissues: Fixation method

Answer 3

• 10% Neutral Buffered formalin at 4°C retains most of the glycogen
• Absolute alcohol causes tissue shrinkage, the polarisation of glycogen to one side of the cell
• Periodic acid-Schiff (PAS) technique
  
  • +/- diastase digestion

Question 4

Causes of depleted glycogen in tissues

Answer 4

• ↓ Production
• ↑ Utilisation

Question 5

Glycolitic/Glycogenolitic enzyme defects

Answer 5

• Accumulation of glycogen or related substances
• Glycogenoses

Question 6

Glycogenoses

Answer 6

• Glycolitic or glycogenolitic enzyme defects
• α-1,4-glucosidase deficiency
• Glucose-6-phosphatase deficiency
• Equine polysaccharide storage myopathy - EPSSM

Question 7

α-1,4-glucosidase deficiency

Answer 7

Shorthorn, Brahman cattle

• Cardiac, hepatic, neuronal glycogen storage

Question 8

Glucose-6-phosphatase deficiency

Answer 8

Von Gierke disease

• Canine toy breeds, Maltese, beagle crosses
• Cardiac, hepatic, renal glycogen storage

Question 9

Equine polysaccharide storage myopathy - EPSSM

Answer 9

• No enzyme defect detected yet
• Glycogen synthase 1 mutation (GYS1)
• Accumulation of glycogen in type II myofibres

Question 10

Glucocorticoid induced hepatocellular degeneration

Answer 10

“Steroid hepatopathy”

• Endogenous/exogenous glucocorticoid excess
  
  • GC → Glycogen synthetase ↑
• Enlarged, pale liver
  
  • Hepatocellular enlargement, mainly midzonal
• CAVE: Normal histological finding in newborn piglets

Question 11

Diabetes Mellitus Type-I

Answer 11

Insulin dependent DM

• β-cell necrosis (insulin deficiency)
• Predisposition (hereditary factors)
• Viral diseases (parvovirus, BVD, FIP, FMD)
• Autoimmune reaction
• Idiopathic

Question 12

Diabetes mellitus Type-II

Answer 12

Many variations, different forms, complex pathogenesis

• Insulin level is normal, but there is no effect on target tissues
• There is no free receptor
• Intracellular mediators are incomplete

Increased, then decreased insulin production

• Langerhans-islet amyloidosis
• Hereditary predisposition
• Polyphagia, adipositas, inactivity

Question 13

Diabetes mellitus Type-S

Answer 13

• Secondary destruction of β-cells
• Antagonism of insulin action by drugs, hormones

Question 14

Lesions of DM

Answer 14

Hepatic lipidosis

• Glycogen deficiency
• Incomplete oxidation of fats
• Ketones produced

Question 15

List the consequences of DM

Answer 15

• Ketoacidosis
• Diabetic coma
• Glycogen accumulation in renal tubuli cells
• Alopecia
• Microangiopathia
• Neuropathia
• Cataracta diabetica