Is the nonoxidative reaction of the HMP shunt reversible or irreversible?
Describe the nonoxidative reaction in the HMP shunt.
Ribulose-5-P is converted to Ribose-5-Phosphate by phosphopentose isomerase and transketolases (p.103)
What cofactor is required by transketolases?
Vitamin B1 (p.103)
What must be activated for the oxidative burst to occur?
Membrane bound NADPH oxidase in neutrophlis, monocytes, etc. must be activated (p.103)
What is the role of the oxidative burst?
Role in immune response causing a rapid release of reactive oxygen intermediates.
What important cofactor contributes to the creation of ROIs (reactive oxygen intermediates) and their neutralization?
What condition is characterized by a deficiency in NADPH oxidase?
Chronic Granulomatous disease (p.103)
What characteristics are unique to the WBCs in a patient with Chronic Granulomatous disease?
WBCs can utilize H2O2 generated by invading organisms and convert this to ROIs (p.103)
Why are patients with Chronic Granulomatous Disease at risk for infection?
Because they neutralize their own H2O2 which leaves their WBCs without the appropriate ROIs to fight infection by catalase positive species (p.103)
Name two common catalase positive organisms.
S. Aureus, Aspergillus (p.103)
Describe the pathology associated with a deficiency in Glucose-6-phosphate dehydrogenase.
Decreased NADPH in RBCs leads to hemolytic anemia due to poor RBC defense against oxidizing agents. Infection can also precipitate hemolysis as free radicals are generated by the inflammatory response and diffuse into RBCs to cause oxidative damage (p.104)
Describe the role of NADPH in detoxification of free radicals.
NADPH keeps glutathione reduced which detoxifies free radicals and peroxides (p.104)
Name four stereotypical oxidizing agents.
Fava beans, sulfonamides, primaquine, antituberculosis drugs (p.104)
Describe the inheritance of G6PD deficiency.
X-linked recessive disorder. It is the most common human enzyme deficiency and is more prevalant in blacks (mutation increases malaria resistance) (p.104)
What two cell types are seen on a blood smear of a patient with G6PD deficiency?
Heinz bodies, bite cells (p.104)
What are Heinz bodies?
Oxidized hemoglobin precipitated within RBCs (p.104)
What are bite cells?
Result from phagocytic removal of heinz bodies by splenic macrophages (p.104)
What are the two most common disorders of fructose metabolism?
Essential fructosuria and fructose intolerance (p.104)
What enzyme is deficient in essential fructosuria?
Defect in fructokinase (p.104)
What enzyme is deficient in fructose intolerance?
Hereditary deficiency in Adolase B (p.104)
What is the inheritance pattern associated with essential fructosuria and fructose intolerance?
Autosomal recessive (p.104)
What are the symptoms of essential fructosuria?
It is a benign, asymptomatic condition (fructose is not trapped in cells) where fructose appears in the blood and urine (p.104)
What are the symptoms of fructose intolerance?
Hypoglycemia, jaundice, cirrhosis, vomiting (p.104)
What is the pathology of fructose intolerance?
Accumulation of fructose-1-phosphate causing a decrease in available phosphate which results in inhibition of glycogenolysis and gluconeogenesis (p.104)
What is the treatment for fructose intolerance?
Decrease intake of both fructose and sucrose (glucose + fructose) (p.104)