Diagnostic Tests in Biology

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Questions and Answers

What is the primary function of ELISA tests?

Detect genetic material

Separate antigens by size

Amplify specific RNA samples

Identify specific pathogen antibodies (correct)

Which technique is used for detecting specific RNA sequences from a pathogen?

Western blot

ELISA

Southern blot

Northern blot (correct)

How does reverse transcription PCR differ from standard PCR?

It targets specific RNA for amplification (correct)

It amplifies DNA from larger samples

It separates genetic material by size

It detects multiple pathogens simultaneously

What immediate response occurs after exposure to allergens in Type 1 hypersensitivity?

Histamine release from mast cells Signup and view all the answers

Systemic anaphylaxis is characterized by what major symptom?

Severe blood pressure drop Signup and view all the answers

Which of the following is a treatment for moderate allergic reactions?

Use of epinephrine Signup and view all the answers

What initiates the sensitization process in Type 1 hypersensitivity?

Primary exposure to an allergen Signup and view all the answers

Type 2 hypersensitivity is primarily caused by what mechanism?

Destruction of cells by cytotoxic immunity Signup and view all the answers

What type of immune response is associated with the destruction of blood cells in hemolytic disease of the newborn?

Type II hypersensitivity Signup and view all the answers

Which of the following is primarily responsible for localized reactions in Type III hypersensitivity?

Immune complexes Signup and view all the answers

What contributes to the delayed reaction in Type IV hypersensitivity?

Migration of macrophages and T cells Signup and view all the answers

Which condition is an example of a systemic reaction associated with Type III hypersensitivity?

Rheumatoid arthritis Signup and view all the answers

What is a common treatment for late-phase allergic contact dermatitis?

Corticosteroids Signup and view all the answers

Which of the following best describes autoimmune diseases?

Loss of self-tolerance leading to autoantibody production Signup and view all the answers

What deficiency is characterized by a lack of B cells?

Agammaglobulinemia Signup and view all the answers

How is HIV primarily transmitted?

Sexual contact and blood products Signup and view all the answers

What is a critical factor in the development of autoimmune diseases in relation to genetics?

Family history and genetic predisposition Signup and view all the answers

Which condition is a result of cytotoxic T cells attacking the myelin sheaths surrounding neurons?

Multiple sclerosis Signup and view all the answers

What is a major clinical manifestation of a systemic infection from HIV?

Opportunistic infections and cancers Signup and view all the answers

What is the primary characteristic of folliculitis?

Infection of hair follicles Signup and view all the answers

What is a common treatment to prevent Staphylococcus aureus infections?

Methicillin and antiseptics Signup and view all the answers

What type of hypersensitivity reaction is associated with poison ivy exposure?

Delayed-type Signup and view all the answers

Study Notes

ELISA Tests

ELISA (enzyme-linked immunosorbent assay) tests are used to detect hormones.
Pregnancy tests and at-home COVID tests are simplified examples of ELISA tests.

Western Blot Test

A highly accurate technique to detect specific antigens in complex mixtures.
Separates antigens by size, reducing misinterpretation.
An example is the HIV ELISA test.

Nucleic Acid Tests (NAT)

Detect pathogen genetic material using molecular techniques.
Southern blot detects specific DNA sequences.
Northern blot detects specific RNA sequences.
Used to detect infection even without symptoms.
Also used to detect cancer.
Probes bind to target molecules to identify specific sequences.

Polymerase Chain Reaction (PCR)

Reverse transcription PCR (RT-PCR) amplifies specific RNA from small samples.
Copies the target molecule exponentially (doubling every cycle): 4, 8, 16, 32 copies.
Detection of a positive result in PCR indicates active replication.

Immunologic Disorders

Type 1 Hypersensitivity

Allergic reactions triggered by allergens.
Common examples: pollen, cats, bee stings, foods, drugs, ragweed, and dust mites.
Exposure releases inflammatory molecules (histamine, kinins, proteases, leukotrienes).
IgE-mediated two-step process:
- Sensitization: Initial exposure activates B cells, producing IgE antibodies targeting the allergen. IgE binds to mast cells, basophils, or eosinophils.
- Degranulation: Allergen binding causes mast cells, basophils, or eosinophils to release histamine and other cytokines.
Symptoms: Skin redness, swelling, watery eyes, and potentially asthma (inhaled allergens).
Systemic Anaphylaxis (anaphylactic shock): From localized to systemic, causing low blood pressure, airway constriction, and rapid death.
Treatment: Immediate epinephrine, avoidance of the allergen.

Type 2 Hypersensitivity

Antibody-mediated destruction of cells.
Complement and antibodies work together.
Examples: Incompatible blood transfusions, hemolytic disease of the newborn, drug reactions (e.g., penicillin).

Type 3 Hypersensitivity

Immune complexes form, some cleared, others lodge in blood vessels or organs.
Leads to inflammation and tissue damage.
Localized reactions: Inhalation of antigens can lead to immune complex formation and complement activation (e.g., farmer's lung, pigeon breeders' lung).
Systemic reactions: Rheumatoid arthritis and systemic lupus erythematosus.

Type 4 Hypersensitivity

Cellular hypersensitivity: Inflammation 12-24 hours after exposure to antigen triggered by antigen-presenting cells, and T-cells response.
Types:
- Contact dermatitis: Poison ivy, latex, soaps.
- Tissue/organ rejection: Post-transplantation.
- Cell-mediated immune response (T Cells): Intense skin rash, treatable with glucocorticoids.
Tuberculin Response: Diagnoses tuberculosis or vaccination exposure; skin reaction (swelling) 24-72 hours post-exposure aids diagnosis. Larger reaction indicates excessive immune response.

Graft Rejection

Recipient's immune system recognizes transplanted tissue/organ as foreign due to MHC or HLA differences.
Immunosuppressive drugs help prevent graft-versus-host disease.

Development of Autoimmune Diseases

Loss of self-recognition (clonal deletion) leads to autoantibodies or cytotoxic T cells attacking normal body components.
More common in older women due to hormone differences and potentially immune exhaustion.
Genetic and environmental factors contribute to autoimmune diseases.
Examples include type 1 diabetes mellitus, multiple sclerosis, rheumatoid arthritis, and autoimmune hemolytic anemia.

Primary Immunodeficiencies

Agammaglobulinemia: B cell deficiency, treated with immune serum and antibiotics.
DiGeorge syndrome: Thymus gland defect, T cell deficiency, treated with thymic stem cells.

Acquired Immunodeficiencies

Infections (leprosy, tuberculosis, AIDS), immunosuppressants (chemotherapy/radiation therapy) damage T/B cells.

HIV/AIDS

Infection by human immunodeficiency virus (HIV).
Targets T helper cells and macrophages.
Results in opportunistic infections/cancers and death.
Transmission: Sexual contact, blood products, mother-to-child transmission.

Bacterial Skin Diseases

Folliculitis: Hair follicle infection.
Staphylococcal Scalded Skin Syndrome: Caused by S. aureus.
MRSA Infections: Methicillin-resistant Staphylococcus aureus.
Necrotizing Fasciitis: Severe tissue infection.
Cat Scratch Fever: Bacterial infection.
Acne: Inflammation of sebaceous glands.
Pseudomonas Infections.
Gas Gangrene

Staphylococcus aureus (S. aureus) Diseases

Common causes of various skin infections, bacteremia, food poisoning, and pneumonia
Gram-positive, facultatively anaerobic.
Can survive in salty and dry conditions (tolerates various environments)
Treatment: Methicillin; prevention: antisepsis.
Spread: Direct contact with infected individuals or surfaces (fomites).

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Description

This quiz covers various diagnostic tests used in biology, including ELISA, Western Blot, Nucleic Acid Tests, and PCR. Explore the principles and applications of these techniques, which are crucial in detecting hormones, pathogens, and genetic material. Test your knowledge on how these assays function and their significance in medical diagnostics.