Medical Interventions - Unit 1 Study Guide

Medical Interventions - Unit 1 Study Guide

Lesson 1.1

1. Definition of Medical Intervention

• Medical Intervention: A measure that is taken to improve health or change the direction of disease progression.

Examples of Medical Interventions Encountered by Sue Smith During Infection with Neisseria Meningitidis:

• Antibiotics: Medications used to treat bacterial infections.

• Soothing food: Nutritional interventions that alleviate symptoms.

ELISA (Enzyme-Linked Immunosorbent Assay): A technique used for detecting and quantifying antigens.

Types of Medical Interventions + Examples

• Diagnostic Interventions

  • Used to identify a disease, injury, or condition.

    • X-rays

    • MRI scans

    • CT scans

    • Ultrasounds

    • Blood tests

    • Genetic testing (PCR, DNA sequencing)

    • Biopsies

    • EKG/ECG

• Therapeutic Interventions

  • Used to treat or manage a condition.

    • Physical therapy

    • Chemotherapy

    • Radiation therapy

    • Medications (antibiotics, antivirals, insulin, etc.)

    • Immunotherapy

    • Dialysis

    • Psychotherapy or counseling

• Surgical Interventions

  • Involve cutting into or operating on the body.

    • Appendectomy

    • Heart bypass surgery

    • Knee/hip replacement

    • Tumor removal

    • C-section

    • Laparoscopic surgery

• Preventive (Prophylactic) Interventions

  • Used to prevent diseases or injuries before they occur.

    • Vaccinations

    • Fluoride treatments

    • Birth control

    • Screening tests (mammograms, colonoscopies)

    • Lifestyle counseling (nutrition, exercise)

    • Prophylactic antibiotics

    • PPE (masks, gloves)

• Rehabilitative Interventions

  • Help restore function after injury or illness.

    • Physical therapy

    • Occupational therapy

    • Speech therapy

    • Cardiac rehab

    • Respiratory therapy

    • Prosthetics & orthotics

• Pharmacological Interventions

  • Treatment using medications.

    • Pain relievers (Tylenol, ibuprofen)

    • Antidepressants

    • Antibiotics

    • Antihypertensives (blood pressure meds)

    • Vaccines (also preventive but still pharmacological)

• Assistive Interventions

  • Tools/tech that help with daily function.

    • Wheelchairs

    • Hearing aids

    • Eyeglasses/contacts

    • Canes/walkers

    • Adaptive devices for eating, writing, etc.

• Genetic Interventions

  • Modify or work with DNA to treat or prevent disease.

    • Gene therapy

    • CRISPR editing

    • Carrier screening

    • Prenatal genetic testing

    • siRNA therapies

• Lifestyle / Behavioral Interventions

  • Changes to daily habits to improve health.

    • Exercise programs

    • Nutritional counseling

    • Smoking cessation programs

    • Stress management programs

• Public Health Interventions

  • Focus on community-level health.

    • Water fluoridation

    • Sanitation systems

    • Vaccination campaigns

    • Public health education

    • Mosquito control programs

2. PCR and Bioinformatics in Pathogen Identification

• PCR (Polymerase Chain Reaction): A laboratory technique used to amplify DNA sequences.

How PCR + Bioinformatics Identify a Pathogen:

• Sample Collection

  • A patient sample (blood, saliva, urine, CSF, etc.) is collected.

  • This sample may contain human cells, bacteria, viruses, or other pathogens.

• DNA Extraction

  • All DNA is isolated from the sample.

  • This includes both the patient’s DNA and any pathogen DNA.

  • Chemicals break open the cells, and the DNA is purified.

• PCR Amplification (Polymerase Chain Reaction)

  • PCR targets a specific gene region that is common in bacteria/viruses but unique enough to identify a species.

    • Steps within PCR:

      • Denaturation: DNA strands separate.

      • Annealing: Primers bind to the target sequence.

      • Extension: Taq polymerase copies the target region.
        After ~30 cycles, millions of copies of only the target pathogen DNA exist.

  • Why this matters:

    • Amplifying the DNA makes it detectable and readable.

    • Even tiny amounts of pathogen DNA become measurable.

• Gel Electrophoresis

  • The PCR products are run in a gel.

  • DNA fragments separate by size.

  • A band in the expected location confirms the PCR worked and that DNA was successfully amplified.

  • This step does NOT identify the pathogen.
    It just checks that PCR produced DNA of the right length.

• DNA Sequencing

  • The amplified DNA is then sequenced.

  • Sequencing reads the exact order of nucleotides (A, T, C, G).

  • This provides a unique genetic “barcode” of the pathogen.

• Bioinformatics – BLAST (Basic Local Alignment Search Tool)

  • The DNA sequence is uploaded into BLAST, an online database.

  • BLAST compares the sequence to thousands of known organisms.

  • It finds the closest match and gives a percent identity score.

    • Example:

      • “99% match to Neisseria meningitidis” → confirms bacterial meningitis

      • “98% match to Influenza A H1N1 strain” → confirms viral flu

• Identification of the Pathogen

  • The highest BLAST match reveals the organism causing the patient’s symptoms.

  • Doctors use this information to choose the right treatment.

3. ELISA for Antigen Detection in Patients

• Process of Antigen-ELISA:

  1. Sample Collection: A sample is taken from the patient.

  2. Wells Preparation: Antigens from the sample are added to plastic wells where they stick to the well sides.

  3. Washing: Unbound antigens are washed away.

  4. Primary Antibody Addition: A primary antibody, which binds to the antigen, is added and allowed to stick to it.

  5. Further Washing: Unbound primary antibodies are washed away.

  6. Secondary Antibody Addition: A secondary antibody that is conjugated to an enzyme is added, and it binds to the primary antibody.

  7. Substrate Addition: A substrate for the enzyme is added, which reacts and produces a color change.

  8. Analysis: The intensity of the color change correlates with the concentration of the antigen; darker colors indicate higher concentrations.

4. Dilution Factor and Protein Concentration

• Volume in Each Tube: 60 µL (multiple tubes)

• Total Volume Calculation: Total volume from multiple tubes is added together.

• Dilution Factors: 1, 1/3, 1/9, 1/27, 1/81, 1/243.

• Protein Concentration in ng/mL:

  • Tube 1: 4000 ng/mL

  • Tube 2: 1333.3 ng/mL

  • Tube 3: 444.4 ng/mL

  • Tube 4: 148.1 ng/mL

  • Tube 5: 49.4 ng/mL

  • Tube 6: 16.5 ng/mL

5. Qualitative and Quantitative Results from ELISA

• Qualitative Results: Comparisons based (e.g., darker colors indicating more antigen presence).

• Quantitative Results: Utilizes serial dilutions to calculate exact antigen amounts.

• Application in Treatment: Helps determine the severity of infection based on the concentration of antigens.

6. Actions Upon Identifying an Outbreak

• Diagnosis:

  • Conduct interviews, find patient zero, quarantine affected individuals, notify authorities, and utilize diagnostic tools like ELISA and BLAST.

• Treatment:

  • Administer antibiotics and manage symptoms to alleviate patient discomfort.

• Prevention:

  • Implement vaccinations and educate the population on practices that prevent the spread of disease.

7. Pathogen Identification - Neisseria Meningitidis

• Type of Pathogen: Gram-negative bacteria.

• Treatment: Antibiotics are effective for treating bacterial infections, particularly those caused by Neisseria meningitidis.

8. Cellular Structures of Bacterium

• Labeling Bacterial Structures:

  • Capsule: Protects bacteria from the immune system.

  • Cell Wall: Provides structure and support.

  • Flagellum: Assists in movement.

  • Cell Membrane: Regulates what enters and exits the bacterium.

  • Nucleoid: Contains the bacterial DNA.

  • Pili: Helps in adhesion to surfaces.

  • Plasmids: Small DNA molecules that can carry genes for antibiotic resistance.

  • Ribosomes: Sites of protein synthesis.

9. Antibiotics Overview and Effects

• Definitions:

  • Bactericidal: Kills bacteria.

  • Bacteriostatic: Slows down bacterial growth and reproduction.

10. Types of Genetic Transfer in Bacteria

• Genetic Transfer Mechanisms:

  • Transformation: Live bacteria take up plasmids from the environment, typically from dead bacteria.

  • Transduction: Involves using bacteriophages (viruses that infect bacteria) to transfer DNA to another bacterium.

  • Conjugation: Transfer of genetic material between two live bacteria that connect via pili to exchange plasmids.

11. DNA Transferred in Bacterial Conjugation

• Type of DNA: Plasmids are the main components transferred during bacterial conjugation.

12. Antibiotic Prescription for Staphylococcus Aureus Skin Infection

• Recommended Antibiotic: The doctor should prescribe the antibiotic associated with the largest zone of inhibition from sensitivity testing.

13. Misuse and Overuse of Antibiotics

• Examples of Misuse:

  • Not completing prescribed antibiotics leads to survival of resistant bacteria.

  • Overuse of antibacterial products contributes to resistance by killing only the less resistant strains, ultimately allowing more resistant bacteria to thrive.

  • Overuse in Factory Farms

    • Concerns regarding livestock health

    • Risks of human illness from infected meat consumption

14. Sound and Hearing

• Definition of Sound

  • Sound: Vibration caused by a sound source in the form of waves that travels through air, water, or other media to our ears.

• Frequency and Amplitude

  • Frequency: Affects pitch, defined by the stretch or wavelength of the wave, measured in Hertz (Hz).

  • Amplitude: Affects loudness/volume, defined by the height of the wave, measured in decibels (dB).

• Interpretation of Sound

  • A higher frequency sound is interpreted as high-pitched.

  • A higher amplitude sound is interpreted as loud.

15. Anatomy of the ear

• Pinna (Auricle): The outer part of the ear that collects sound waves.

• Auditory Canal: Pathway that directs sound to the eardrum.

• Tympanic Membrane: Also known as the eardrum, vibrates with sound.

• Ossicles: Three tiny bones in the middle ear - Malleus, Incus, Stapes.

  • Malleus (Hammer)

  • Incus (Anvil)

  • Stapes (Stirrup)

• Cochlea: Spiral-shaped organ that converts sound vibrations into nerve impulses.

• Cochlear Nerve: Transmits auditory information from the cochlea to the brain.

• Eustachian Tube: Connects the middle ear to the back of the throat; helps equalize pressure.

• Semicircular Canals and Vestibular system: Part of the inner ear responsible for balance.

16. Hearing Loss Diagnosis Tests

• Rinne Test: Used to diagnose conductive hearing loss with a tuning fork.

• Speech in Noise Test: Assesses how well a person can hear speech against background noise.

17. Types of Hearing Loss

• Conductive Hearing Loss

  • Caused by damage to the outer or middle ear.

  • Can occur due to blockages in the ear canal or issues affecting the bones (ossicles).

  • Often caused by age, genetics, or infections.

• Sensorineural Hearing Loss

  • Resulting from damage to the inner ear or auditory nerve.

  • Possible causes include infections or injuries.

18. Audiogram Interpretation

• A patient has mild hearing loss at frequencies above 1,000 Hz.

• Audiogram of Familiar Sounds: (Values in dB and Hz)

  • Normal hearing at low frequencies.

  • Mild hearing loss at mid frequencies (1,000 Hz - 2,000 Hz).

  • Moderate-severe hearing loss at high frequencies (> 2,000 Hz).

• Example Sounds:

  • Chirping: Can hear

  • Crying, Vacuuming, Jackhammer: Levels vary by hearing loss classification.

Medical Interventions for Hearing Loss

• Examples of interventions include:

  • Hearing aids

  • Speech translators

  • Medications (antibiotics)

  • Surgeries (including cochlear implants)

Cochlear Implant Debate

Arguments For Cochlear Implants

1. Improved hearing for users.

2. Increased opportunities for communication.

3. Enhances integration into society.

Arguments Against Cochlear Implants

1. Sensitivity towards Deaf culture, which might feel threatened.

2. Permanent alteration that destroys nerve cells.

3. Risks associated with surgery (e.g., costs, complications).

16. Edward Jenner and Vaccination

• Known as the "Father" of vaccinations.

• Developed the smallpox vaccine by using the cowpox virus to immunize against smallpox.

• Initiated vaccination programs, significantly impacting public health.

Definition and Function of Vaccines

• Vaccine: A preparation that uses part or all of a pathogen (virus/bacteria), which can be live, dead, weakened, or altered to stimulate an immune response, resulting in the production of antibodies against specific antigens.

• Booster Shots: Sometimes required to maintain immunity levels as the body

• s ability to recognize pathogens may decrease over time.

Vaccine Utilization for Disease Eradication

1. Protects unvaccinated individuals through herd immunity.

Vaccine Manufacturing Methods

• Killed: Pathogenic agents are killed to prevent disease.

• Toxoid: Antibodies are produced against toxins.

• Subunit: Antigens or markers are made using parts of the pathogen.

• Naked DNA: Injecting altered DNA directly into the host.

17. Engineering Plasmids and Vaccines

Restriction Enzyme Usage

1. Plasmids are cut using restriction enzymes to create sticky ends.

2. Desired vaccine genes from a virus are inserted into the plasmid and then glued with ligase.

3. The recombinant plasmid is transformed into bacteria for replication.

Example Restriction Enzymes

• Bam HI: Cuts to create sticky ends.

• Eco RI: Cuts to create sticky ends.

• Hpa I: Cuts blunt ends, which are not suitable for ligation with sticky ends.

DNA Sequence Example

• DNA sequences show restriction sites for Bam HI and Eco RI and their cuts:

  • $(G GATCC)$

  • $(CCTAG G)$

  • $(G AATTC)$

  • $(CTTAA G)$

  • $(GTT AAC)$

  • $(CAA TTG)$

18. Epidemiology Fundamentals

• John Snow

  • Recognized as the "Father" of epidemiology.

  • Conducted case-study research on cholera to trace infection sources and prevent further outbreaks.

Attack Rate Calculation

• Attack Rate: Calculated using the formula:
  $(\text{Attack Rate} = \frac{\text{Number of ill}}{\text{Total population}})$

• A higher attack rate may indicate the source of infection.

Cohort vs Case-Control Studies

Cohort Study

• Prospective study tracking subjects over time, based on exposure to known risk factors.

• Example: Studying high school students using ear buds over a decade.

Case-Control Study

• Retrospective study identifying subjects with disease and looking backward to find exposures.

Differences in Addressing Disease Outbreaks and Chronic Illnesses