HBF 102 Enzymes in Clinical Diagnosis Quiz

Course Information

• Course: Biochemistry
• Year: 1
• Module: Human Body Function (HBF 102)
• Semester: 1
• Academic Year: 2024-2025
• Faculty: Medicine, Helwan National University
• Instructor: Prof. Dr. Mohamed I. Kotb & Ass. Prof. Dr. Ahmed M. A. Akabawy

Lecture: Enzyme III

• Topic: Enzymes in Clinical Diagnosis
• Lecturer: Prof. Dr. Mohammed Kotb & Assoc. Prof. Dr. Ahmed M. A. Akabawy

Objectives

• Analyze types of plasma enzymes
• Recognize enzymes important in clinical diagnosis
• Identify diagnostic biomarkers important in Myocardial infarction

Introduction

• Topic: Plasma Enzymes
• Subtopics: Definition, Types, Biological Importance, Myocardial Infarction, Biomarkers of MI

Plasma Enzymes

• Functional: Have known function in the plasma (e.g., clotting factors)
• Non-Functional: Have no function in the plasma; released into plasma during cell turnover from some damaged organs (e.g., transaminases)

Objectives

• Analyze plasma enzyme types
• Recognize diagnostically important enzymes
• Identify myocardial infarction biomarkers

Non-functional Plasma Enzymes in Health & Disease

• Normal tissue in cells with normal enzyme activity
• Tissue damage in cells, causing enzyme release into the blood stream
• Cell death in cells, causing enzyme release into the blood stream
• Elevated enzyme activity in the blood stream

Isoenzymes

• Multiple forms of the same enzyme catalyzing the same reaction but differing in their molecular structure, chemical characteristics, and localization depending on the tissue.
• Important diagnostic tool for identifying the location and severity of a disease (examples: LDH, CK, ACP, ALP)

Analyzing Plasma Enzymes

• Performing an assay to determine the concentration of particular plasma enzymes in blood for diagnosing or monitoring a condition

Why Plasma Enzymes are Important in Clinical Diagnosis

• Small amounts of intracellular enzymes are normally present in the blood due to normal cell turnover.
• When tissue damage occurs, increased amounts of enzymes are released into the blood, which results in elevated enzyme concentrations.

LDH (Lactate Dehydrogenase)

• Tetrameric protein with two subunit types (H and M) in heart and skeletal muscle.
• Catalyzes lactate to pyruvate conversion.
• Re-oxidizes NADH back into NAD.
• Five isoenzymes: LDH-1, LDH-2, LDH-3, LDH-4, and LDH-5
• Their location differs: LDH-1: Heart and Red Blood Cells; LDH-2: Heart and Red Blood Cells; LDH-3: Lungs; LDH-4: Kidney, Pancreas; LDH-5: Liver and Skeletal muscles.
• Elevated in myocardial infarction (MI).
• LDH-1/LDH-2 ratio diagnostic indicator for MI
• Elevated LDH-1/LDH-2 ratio in heart attack

CK (Creatine Kinase)

• Dimeric protein with two subunit types (B and M) in Brain and Muscle.
• CK-1(BB): Brain
• CK-2(MB): Heart
• CK-3(MM): Skeletal Muscle
• Elevated in myocardial infarction (MI) and skeletal muscle diseases

Transaminases (ALT & AST)

• ALT primarily in liver cells (cytosolic)
• AST in liver cells (mitochondrial) and heart muscle (cytosolic)
• AST and ALT levels are frequently compared and interpreted for diagnostic purposes
• Elevated ALT > AST in acute hepatitis and liver necrosis

Phosphatases

• Enzymes removing a phosphate group from its substrate
• Alkaline Phosphatase (ALP) pH 9-10.5
• Acid Phosphatase (ACP) pH 5-6
• ALP: Increased in cholestasis and bone diseases (e.g., rickets, osteomalacia).

Gamma-glutamyl transferase (“GGT”)

• Helps diagnose liver bile duct issues
• Increased GGT in bile duct obstructions and alcoholic hepatitis

5'-nucleotidase (5'-NT)

• Protein produced by the liver
• Used to assess liver function and cholestasis

Myocardial Infarction

• Sudden decrease in blood supply to the myocardium.
• Causes ischemia (inadequate oxygen supply)
• Prolonged ischemia leads to infarction (irreversible damage).
• Pathophysiology includes atherosclerosis, arterial spasms, and thrombi
• Leads to hypoxia and necrosis.

Risk Factors for MI

• Non-modifiable: Sex (males more common), Age, Family History.
• Modifiable: Smoking, Dyslipidemia, Diabetes, Hypertension, Obesity, Sedentary Lifestyle, Peripheral Vascular Disease

Symptoms of MI

• Chest discomfort
• Arm or back discomfort
• Neck or jaw discomfort
• Pain described as aching, crushing, squeezing.
• Tightness, Heaviness, Pressure

Cardiac Biomarkers for AMI

• Enzyme: LDH1, CK-MB, AST1, Troponin I
• Myoglobin (non-specific)
• Onset, peak, and return to baseline times vary for each biomarker

Troponins

• Contractile proteins in heart muscle.
• Cardiac troponin I and T are sensitive and specific indicators for cardiac damage.
• Elevated levels above reference ranges indicate heart muscle damage.

Test your knowledge on the role of plasma enzymes in clinical diagnosis, including their types and functions. This quiz covers important biomarkers relevant to conditions like myocardial infarction. Enhance your understanding of how these enzymes aid in medical assessments.