Human Metabolism: Carbs, Fats, Proteins

Question 1

What biochemical changes do you get in gestational diabetes mellitus GDM

Answer 1

Normal or raised insulin levels
HIgh levels of plasma fatty acids
Ketone bodies = High ketones and ketonuria are considered diagnostic for GDM

Question 2

What is phenylketonuria

Answer 2

Disease about 1 in 10,000 babies. Caused by absence or great reduction int he phenylalanin hydroxylase enzyme. This means that the phenylalanine amino acid cannot be metbaolised

This means that the amino acids starts taking place in weird reactions that would normally occur producing various new compounts Phenylpyruvate, phenyllactate, and phenylacetate. These start to occur in the urine.

Question 3

What are the consequences and patholophysiology of phenylketonuria

Answer 3

THe high levels of phenylalanine saturate the amino acid transporters so no other AA can go through. Inhibits synthesis of NTs and myelin in the brain. Also interferes with mitochondria which makes the brain very susceptible as it is a very oxidative organ.

Question 4

What are the clinical features of phenylketonuria

Answer 4

Untreated = Causes gross mental restriction with IQ below 50. BUt there are screening programmes now with the Guthrie test.
Note that phenylalanine is used to make another AA tyrosine, and this is used as a precursor to melanin. So you can get a degree of albinoism in PKU.

Question 5

What is the treatment of phenylketonuria

Answer 5

Need to give a feeding regimen that has all but a very limited about of phenlalanamine. This should be followed by the mother as well during pregnancy

Question 6

How is metabolism different in the maternal-foetal unit? in the different stages of pregnancy?

Answer 6

There is an initial increase in insulin sensitivity in early pregnancy, then a mild insulin resistance develops in the mother.

Resulting in = Anabolic activities in the beginning like lipogenesis and deposition of fat in the frist trimester. But later in pregnancy nutrient uptake by the foetus occurs at the expense of the mother.
Also in later phases = Maternal tissues take up little glucose but instead oxidise abundant fatty acids and ketone bodies.
By contrast foetus uses much glucose,

Remember that maternal blood glucose levels are predictive of birth weight. The ofetus has little ability to oxidise ketone bodies or fat.

Question 7

How does the metabolism work in a newborn baby

Answer 7

Glycogen = Stored in the liver, and liver can also udnergo gluconeogenesis. This is how newborne regulates blood gllucose levels.

Fatty acid oxidation = Initially unable to as foetus, but rapidly increases ability to as newborne.
The dietary fats that babies get from milk are also very important, for example omega 3 and a-linoleic acid which are needed for specialised membranes of the CNS.
Fatty acids are also consumed by the brown adipose tissue = They have no muscle to generate heat, so instead rely on these large deposits of brown fat.