Biochemistry Clinicals: Scurvy Overview

Biochemistry Clinicals (LOCO)

• Scurvy (Infantile Scurvy/Barlow's Disease):
  • Signs and Symptoms: Collagen synthesis impairment, capillary hemorrhage, muscle weakness, and bone weakness (swollen/soft gums).
  • Wound Healing: Impaired wound healing and development of bones (dentine & cartilage).
  • Causes: Vitamin C deficiency (low intake of fresh vegetables), resulting in poor collagen synthesis.
  • Vitamin C Sources: Citrus fruits (tomato, banana, apple), liver, milk, and other sources.
  • Vitamin C Forms: Ascorbic acid and dehydroascorbic acid.

Breakdown of the Information

• Vitamin C deficiency leads to scurvy.
• Scurvy affects collagen, capillaries, and bone growth.
• Citrus fruits are rich sources of vitamin C.

Other Topics from the Notes

• L-Gluconic Lactone Oxidase:

  • Enzyme absent in humans, leading to lack of vitamin C production.
  • Important for collagen synthesis.

• Collagen Hydroxylation:

  • Vitamin C is essential for the formation of collagen.
  • It helps stabilize the structure of collagen by improving the network formation and resulting in better collagen formation.

• Iron Absorption:

  • Vitamin C helps iron absorption by regulating the conversion of Fe⁺² to Fe⁺³.

• Antioxidant Properties of Vitamin C:

  • Its antioxidant role protects cells against damage and prevents diseases like heart disease and cancer.

• Role of Tryptophan in Metabolism:

  • Tryptophan plays a vital role in the synthesis of immunoglobulins, corticosteroids, and THF.
  • It's involved in wound healing and plays a large role in tyrosine metabolism.

• Toxicity of Vitamin C:

  • Can cause kidney stones if taken in high amounts over a long time.
  • Also causes negative side effects and problems with digestive health.

• Osteoporosis:

  • Cause: Low calcium intake.
  • Symptoms: Postmenopausal osteoporosis can lead to estrogen decline and bone maturation problems.
  • Treatment: Increased calcium absorption via 1,25(OH)2D (vitamin D) supplementation.

• Calcium Recommendations:

  • Daily calcium intake recommendations vary by age and sex group (children, adult males, and females).

• Absorption Factors (Factors affecting vitamin D and Calcium absorption):

  • Vitamin D, parathyroid hormone (PTH), low pH, lactose, amino acids (lysine, arginine).

• Plasma Calcium Level Regulation:

  • Vitamin D, PTH, calcitonin play a key role.
  • These hormones help regulate calcium levels to keep the correct balance.

• Hypercalcemia:

  • Characterized by high plasma calcium levels.

• Hypocalcemia:

  • Characterized by low plasma calcium levels.

• Bone-related Disorders (Rickets and Osteomalacia):

  • Cause: Vitamin D deficiency affects bone mineralization.
  • Symptoms: Muscle weakness, and bone deformities (bowed legs, etc.).

• Vitamin D Metabolism:

  • 7-dehydrocholesterol is converted to cholecalciferol in the skin via UV-light.
  • Cholecalciferol is converted to 25-hydroxycholecalciferol in the liver.
  • 25 hydroxycholecalciferol is converted to 1,25-dihydroxycholecalciferol in the kidneys.

• Regulation of 1-hydroxylase:

  • Plasma calcium (Ca⁺⁺) and phosphorus(P) indirectly regulate 1-hydroxylase.

• Function of Calcitriol:

  • Increases calcium absorption in the intestines.
  • Increases calcium reabsorption in the kidneys.
  • Promotes bone formation.

• Sources of Vitamin D:

  • Fatty fish, liver, egg yolks, exposure to sunlight.

• Vitamin D Toxicity:

  • Can cause nausea and kidney stones.

• Maple Syrup Urine Disease (MSUD):

  • Genetic disorder affecting branched-chain amino acid metabolism.
  • Symptoms: Urine with a sweet odor, feeding problems, lethargy, convulsions.
  • Diagnosis: Analyzing urine and blood for specific amino acid levels and their corresponding keto-acids can help diagnose.

• Ehlers-Danlos Syndrome (EDS):

  • Genetic connective tissue disorder affecting collagen production.
  • Symptoms: Joint hypermobility, skin hyperextensibility.

• Marfan Syndrome:

  • Genetic disorder affecting fibrillin-1 protein contributing to skeletal and connective tissues.
  • Symptoms: Tall stature, long limbs, flexible joints, eye problems (aorta).

• Mucopolysaccharidoses (MPS):

  • Hereditary metabolic disorders affecting glycosaminoglycan degradation and metabolism.
  • Symptoms: Mental retardation, skeletal abnormalities, and other symptoms.

Explore the critical aspects of infantile scurvy, also known as Barlow's Disease, including its signs, symptoms, and the impacts of Vitamin C deficiency on collagen synthesis and wound healing. This quiz will assess your understanding of Vitamin C sources and the biochemical processes involved in scurvy. Test your knowledge about this important topic in biochemistry!