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Questions and Answers
What was the primary finding in the muscle biopsy of the patient?
What was the primary finding in the muscle biopsy of the patient?
- Hyperplasia of muscle tissue
- Increased muscle fibers
- Lipid deposition (correct)
- Infiltration of immune cells
Which of the following is a consequence of low carnitine levels?
Which of the following is a consequence of low carnitine levels?
- Enhanced use of long-chain fatty acids
- Inability to utilize long-chain fatty acids (correct)
- Increased energy metabolism from carbohydrates
- Improved lipid metabolism
What condition indicates a diagnosis of carnitine deficiency?
What condition indicates a diagnosis of carnitine deficiency?
- High plasma levels of carnitine
- Increased carnitine synthesis
- Below normal carnitine levels (correct)
- Elevated free fatty acid levels
Which treatment was initiated for the patient diagnosed with carnitine deficiency?
Which treatment was initiated for the patient diagnosed with carnitine deficiency?
What improvements were noted within 1 month of starting treatment?
What improvements were noted within 1 month of starting treatment?
What type of fatty acids accumulate due to the impaired utilization from low carnitine levels?
What type of fatty acids accumulate due to the impaired utilization from low carnitine levels?
What is a genetic defect related to carnitine deficiency?
What is a genetic defect related to carnitine deficiency?
What is typically observed in plasma levels of carnitine in affected individuals?
What is typically observed in plasma levels of carnitine in affected individuals?
What indicates a failure in carnitine synthesis?
What indicates a failure in carnitine synthesis?
What are the characteristics of Methylmalonic Acidemia in relation to enzyme defects?
What are the characteristics of Methylmalonic Acidemia in relation to enzyme defects?
Which statement correctly describes the oxidation of unsaturated fatty acids?
Which statement correctly describes the oxidation of unsaturated fatty acids?
Which type of pathway is ω-oxidation considered in fatty acid metabolism?
Which type of pathway is ω-oxidation considered in fatty acid metabolism?
What effect does a deficiency in the mutase enzyme have on fatty acid metabolism?
What effect does a deficiency in the mutase enzyme have on fatty acid metabolism?
When referring to naturally occurring fatty acids, what is true about their double bonds?
When referring to naturally occurring fatty acids, what is true about their double bonds?
Which of the following accurately describes the characteristics of propionate and methylmalonate in urine?
Which of the following accurately describes the characteristics of propionate and methylmalonate in urine?
What is the main implication of developmental retardation in Methylmalonic Acidemia?
What is the main implication of developmental retardation in Methylmalonic Acidemia?
Which enzyme is specifically involved in shifting the double bond in monounsaturated fatty acids during oxidation?
Which enzyme is specifically involved in shifting the double bond in monounsaturated fatty acids during oxidation?
Which of the following is a consequence of the incomplete oxidation of fatty acids?
Which of the following is a consequence of the incomplete oxidation of fatty acids?
What is a physiological characteristic of the acetone produced in untreated diabetes mellitus?
What is a physiological characteristic of the acetone produced in untreated diabetes mellitus?
Which of the following best describes the relationship between ketonemia and ketonuria?
Which of the following best describes the relationship between ketonemia and ketonuria?
What odorous characteristic can be observed in untreated diabetic patients?
What odorous characteristic can be observed in untreated diabetic patients?
Why is excessive ketone body production particularly dangerous in untreated diabetic patients?
Why is excessive ketone body production particularly dangerous in untreated diabetic patients?
What role do peripheral tissues play in the utilization of ketone bodies during ketosis?
What role do peripheral tissues play in the utilization of ketone bodies during ketosis?
What happens to acetoacetate in untreated diabetic patients?
What happens to acetoacetate in untreated diabetic patients?
What is one potential cause of carnitine deficiency in newborns?
What is one potential cause of carnitine deficiency in newborns?
Which of the following is a sign of carnitine deficiency?
Which of the following is a sign of carnitine deficiency?
How does hemodialysis contribute to carnitine deficiency?
How does hemodialysis contribute to carnitine deficiency?
What is one physiological effect of eicosanoids?
What is one physiological effect of eicosanoids?
What symptom can result from lipid accumulation due to carnitine deficiency?
What symptom can result from lipid accumulation due to carnitine deficiency?
What type of treatment is recommended for carnitine deficiency?
What type of treatment is recommended for carnitine deficiency?
Which of the following statements about prostaglandins is true?
Which of the following statements about prostaglandins is true?
In carnitine deficiency, what happens to plasma free fatty acids?
In carnitine deficiency, what happens to plasma free fatty acids?
What is the role of eicosanoids in the body?
What is the role of eicosanoids in the body?
Why is carnitine not stored to any appreciable extent in the body?
Why is carnitine not stored to any appreciable extent in the body?
What condition is characterized by the abnormal build-up of phytanic acid leading to vision loss and a loss of smell?
What condition is characterized by the abnormal build-up of phytanic acid leading to vision loss and a loss of smell?
Which of the following fatty acids are typically accumulated in the brain due to peroxisomal dysfunction in Zollweger’s Syndrome?
Which of the following fatty acids are typically accumulated in the brain due to peroxisomal dysfunction in Zollweger’s Syndrome?
Which pharmacological category does NOT affect the synthesis of leukotrienes?
Which pharmacological category does NOT affect the synthesis of leukotrienes?
What kind of inhibitor is Aspirin classified as regarding prostaglandin synthesis?
What kind of inhibitor is Aspirin classified as regarding prostaglandin synthesis?
Which of the following is NOT a consequence of defective peroxisomal function?
Which of the following is NOT a consequence of defective peroxisomal function?
What role does phospholipase A2 play in the context of cell signaling?
What role does phospholipase A2 play in the context of cell signaling?
Which of the following statements about NSAIDs is accurate?
Which of the following statements about NSAIDs is accurate?
Which of the following represents a potential outcome of Zellweger's Syndrome?
Which of the following represents a potential outcome of Zellweger's Syndrome?
What is the main reason for the accumulation of phytanic acid in Zellweger's Syndrome?
What is the main reason for the accumulation of phytanic acid in Zellweger's Syndrome?
Which of the following accurately describes the consequences of a lack of peroxisomes?
Which of the following accurately describes the consequences of a lack of peroxisomes?
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Study Notes
Diagnosis and Treatment of Carnitine Deficiency
- Signs of muscle weakness and lipid deposition observed in skeletal muscles.
- Diagnosis confirmed by below normal levels of carnitine in muscle biopsy and plasma.
- Genetic defects include:
- Congenital absence of carnitine acyltransferase.
- Defective carnitine synthesis leading to low carnitine concentration.
- Consequence of deficiency:
- Inability to utilize long-chain fatty acids as a metabolic fuel.
- Accumulation of toxic free fatty acids and branched-chain acyl groups in cells.
- Treatment initiated with daily administration of 174 mg/kg L-carnitine.
- Improvement seen within a month: increased activity and decreased irritability.
Vitamin B12 Deficiency
- Methylmalonic acidemia and aciduria can arise from:
- Inability to synthesize vitamin B12 coenzyme or mutations in mutase.
- Symptoms may include metabolic acidosis and developmental retardation.
- Propionate and methylmalonate detected in urine as byproducts.
Fatty Acid Oxidation
- Unsaturated fatty acids make up 50% of body fatty acids; they yield less energy due to lower reduction state.
- Oxidation primarily occurs through the β-oxidation pathway, aided by specific enzymes.
- Natural fatty acids predominantly contain cis double bonds; β-oxidation addresses trans configurations via isomerization.
Alternative Pathways for Fatty Acid Oxidation
- ω-oxidation involves oxidation of terminal methyl groups forming ω-hydroxy fatty acids; a minor pathway.
- Carnitine deficiency more prevalent in newborns, notable in preterm cases due to insufficient synthesis or renal leakage.
Prostaglandins and Related Compounds
- Eicosanoids such as thromboxanes and leukotrienes are potent compounds with diverse physiological impacts, produced in trace amounts across tissues.
- Prostaglandins are not stored and have short half-lives; they play critical roles in local signaling.
Synthesis and Regulation of Prostaglandins
- Cortisol inhibits phospholipase A2, reducing availability of arachidonic acid for prostaglandin synthesis.
- NSAIDs, including aspirin and phenylbutazone:
- Aspirin is an irreversible inhibitor of prostaglandin synthesis.
- Other drugs provide reversible inhibition of synthesis.
Zellweger Syndrome
- Rare inherited condition characterized by absence of peroxisomes, leading to accumulation of polyenoic acids in brain tissue.
- Results in severe defects due to impaired oxidation of long-chain fatty acids.
Ketonemia and Ketonuria
- Acetone is a nonmetabolizable byproduct of ketone body metabolism; can be detected in breath of untreated diabetic patients.
- High levels of ketone bodies lead to diabetic ketoacidosis; characterized by fruity breath odor and high production of ketones.
- Ketonuria (presence of ketones in urine) aligns with ketonemia during ketosis.
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