FA/AMBOSS Vit B1 12/27

Question 1

Vit B1 name?

Answer 1

thiamine

Question 2

active form of B1?

Answer 2

Active form: thiamine pyrophosphate (TPP)

Question 3

how is activated B1?

Answer 3

activation via intracellular phosphorylation of thiamine

Question 4

source of B1?

Answer 4

Sources: whole-grain cereals (e.g., whole wheat, brown rice), yeast, pork, legumes

Question 5

vit B1 transport in blood?

Answer 5

Transport in blood: mainly via blood cells; only ∼10% is free or bound to albumin

Question 6

General function of B1 (tiksliau TPP)?

Answer 6

Cofactor for 4 dehydrogenase enzymes involved in carbohydrate and amino acid metabolism

Question 7

what are 4 enzymes?

Answer 7

Pyruvate dehydrogenase
Alpha-ketoglutarate acid dehydrogenase
Branched-chain ketoacid dehydrogenase
Transketolase

Question 8

what are 4 enzymes?
...........
Alpha-ketoglutarate acid dehydrogenase 
Branched-chain ketoacid dehydrogenase
Transketolase

Answer 8

Pyruvate dehydrogenase

Question 9

what are 4 enzymes?
Pyruvate dehydrogenase
.............
Branched-chain ketoacid dehydrogenase
Transketolase

Answer 9

Alpha-ketoglutarate acid dehydrogenase

Question 10

what are 4 enzymes?
Pyruvate dehydrogenase
Alpha-ketoglutarate acid dehydrogenase 
.............
Transketolase

Answer 10

Branched-chain ketoacid dehydrogenase

Question 11

what are 4 enzymes?
Pyruvate dehydrogenase
Alpha-ketoglutarate acid dehydrogenase 
Branched-chain ketoacid dehydrogenase
.............

Answer 11

Transketolase

Question 12

what does pyruvate dehydrogenase?

Answer 12

(connects glycolysis to citric acid cycle): pyruvate → acetyl-CoA

Question 13

what does alpha-ketoglutarate dehydrogenase?

Answer 13

(TCA cycle): α-Ketoglutarate → succinyl-CoA

Question 14

where participates transketolase?

Answer 14

HMP shunt

Question 15

what does Branched-chain ketoacid dehydrogenase?

Answer 15

Valine/isoleucine → Propionyl-CoA

Leucine → Acetyl-CoA

Question 16

B1 deficiency causes?

Answer 16

Heavy drinking
Malnutrition, starvation
Malabsorption

Malignancy
Diarrhea, prolonged vomiting
Diuretics, hemodialysis
Bariatric surgery

Question 17

pathophysiology of B1 def?

Answer 17

Thiamine deficiency → impaired glucose breakdown → ATP depletion → tissue damage that primarily affects highly aerobic tissues (e.g., brain, heart)

Question 18

what happens if give glucose before restoration of thiamine?

Answer 18

High-dose glucose infusions lead to increased ATP depletion, which can trigger Wernicke encephalopathy

Question 19

In malnourished individuals and chronic alcohol users/heavy drinkers, thiamine should be administered before glucose infusions.

Answer 19

.

Question 20

why manifest beriberi in b1 def?

Answer 20

inadequate thiamine uptake due to malnutrition, heavy drinking, or increased demand (e.g., hyperthyroidism, pregnancy)

Question 21

what is dry beriberi? manifestation

Answer 21

NEURO!!
!!Symmetrical peripheral neuropathy (sensory and motor)
Progressive muscle wasting
Paralysis
Confusion

Question 22

what is wet beriberi?

Answer 22

Cardiomegaly
Edema
!!High-output cardiac failure (dilated cardiomyopathy)

Question 23

diagnosis of b1 def?

Answer 23

vitamin B1 administration → ↑ RBC transketolase activity

Question 24

wernicke encephalopathy manifestation?

Answer 24

An acute neurological syndrome caused by thiamine deficiency that is characterized by a triad of confusion, ophthalmoplegia, and ataxia. Requires emergency treatment with thiamine repletion. Typically occurs in alcoholics.

Question 25

what is wernicke-korsakoff syndrome?

Answer 25

triad (confusion+ophtalmoplegia+ataxia) and confabulation, personality change, memory loss (permanent).

Question 26

what is wernicke-korsakoff syndrome? where is damage in bran?

Answer 26

damage to medial dorsal nucleus of thalamus, mammillary bodies.