Medical Interventions (MI) End of Course Exam Review

1.1 Medical Interventions and Infectious Agents

Medical interventions maintain health and homeostasis.
Methods exist to detect and identify infectious agents.
Medical Intervention Definition: A measure to improve health or alter the course of an illness. Used to prevent, diagnose, and treat disease.
Categories of Medical Interventions:
- Genetics
- Pharmacology
- Diagnostics
- Surgery
- Immunology
- Medical Devices
- Rehabilitation
Gathering Evidence During Outbreaks:
- Link symptoms to suspected disease-causing agents.
- Signs: Measurable and recordable issues (temperature, heart rate, rash, swollen glands).
- Symptoms: Problems reported by the patient (tiredness, sore throat, nausea).
- Determine the root cause of the infection.
- Find "Patient 0" to understand the disease's origin and spread.
Bioinformatics: Collection, classification, storage, and analysis of biochemical and biological information using computers to identify disease pathogens.
DNA Sequencing: Used to identify disease pathogens.
- Isolate the disease-causing agent.
- For meningitis, take a sample of cerebrospinal fluid (CSF) via spinal tap.
- Process CSF to separate human components from disease-causing agents.
- Plate the CSF to allow bacteria to grow outside the body.
- Lyse bacteria and isolate their DNA.
- Amplify the DNA and run it through a DNA sequencing machine.
- Input the DNA sequence into BLAST, which compares it to a database.
Antibodies: Identify and inactivate antigens.
- Antigen: Protein on the outside of cells (and viruses) used for identification.
- Antibodies: Proteins produced by B lymphocytes that attach to foreign antigens, neutralizing them and signaling other leukocytes to destroy them.
ELISA Assay: Used to detect disease.
- Enzyme-Linked Immunosorbent Assay
- Color changes indicate a positive result; stronger colors mean more antigen is present.
- Begin with a pre-treated tray with wells coated with antibodies for the pathogen.
- Add patient serum to the wells. If the antigen is present, it will bind to the antibodies.
- Add a primary antibody to latch onto the antigen.
- Add a secondary antibody with an enzyme attached.
- Add a substrate that the enzyme responds to, causing a color change.
Importance of Knowing Antigen Concentration: Helps determine appropriate treatment.
Serial Dilution: Created and used to compare the results of an ELISA.
- Begin with a known concentration of antigen and dilute it.
- Compare patient samples to the serial dilution to determine the amount of infectious agent in the body.

1.2 Antibiotics and Bacterial Resistance

Antibiotics disrupt pathways that bacteria use to survive.
Bacteria use multiple pathways to gain resistance to antibiotics.
Overuse and misuse of antibiotics promote the selection of resistant bacteria.
How Antibiotics Work: Disrupt pathways bacteria use to survive.
- Inhibit protein synthesis.
- Disrupt the cell wall. Different antibiotics work differently.
Gram-Positive vs. Gram-Negative Bacteria:
- Gram-positive: Thick cell wall made of peptidoglycan.
- Gram-negative: Thin cell wall with an outer membrane containing lipopolysaccharides (endotoxins).
  - Cell wall contains multiple layers, including a thin layer of peptidoglycan.
  - The outside layer is called the outer membrane, which is made of a lipid bilayer whose outside is composed of lipopolysaccharides called endotoxins.
  - The outer membrane serves as a barrier to the passage of most molecules and contains specialized proteins, called porins, which allow certain molecules to pass through the membrane.
  - The region between the plasma membrane and the outer membrane is called the periplasm and is filled with a gel-like fluid and proteins involved in a variety of cellular activities.
  - The Gram-stained cell is pinkish-red.
- Gram Positive Bacteria
  - The cell wall contains a thick layer of peptidoglycan and teichoic acids. There is approximately twenty times more peptidoglycan than the Gram negative bacteria.
  - There is no outer membrane present.
  - There are no porins present.
  - The Gram-stained cell is purple.
Bacterial Cell Components: Nucleoid, Plasmids, Ribosomes, Cell Wall, Plasma Membrane, Capsule, Flagella, Pili, Endotoxins
Mechanisms of Action of Antibiotics:
- β-Lactam Antibiotics: Inhibit enzymes involved in cell wall synthesis.
- Tetracyclines: Block tRNA attachment to ribosomes, preventing protein synthesis.
- Fluoroquinolones: Inhibit topoisomerases, preventing DNA supercoiling.
- Sulfonamides: Inhibit folic acid biosynthesis.
How Bacteria Share Antibiotic-Resistant Genes: Transduction, Transformation, Conjugation (most common).
- Conjugation: Bacteria link pili and exchange plasmids.
- Transformation: Scavenge plasmids from dead bacterial cells.
- Transduction: Resistance delivered via a vector.
Human Actions Contributing to Antibiotic Resistance: Overuse and misuse of antibiotics.
- Adding antibiotics to animal feed.

1.3 Hearing Loss

Problems in the ear cause various types of hearing loss.
Interventions are available to help people with hearing loss.
Frequency and Amplitude: Affect how humans interpret sound.
- Intensity (Loudness): Measured in decibels.
- Frequency: Number of sound waves that cross a point in a certain amount of time (determines pitch).
- Amplitude: Height of sound waves (determines loudness).
Parts of the Ear and Their Function: Pinna, Auditory Canal, Tympanic Membrane, Ossicles (Malleus, Incus, Stapes), Oval Window, Cochlea, Auditory Nerve, Vestibule, Semicircular Canals, Vestibular Nerve, Eustachian Tube
Causes of Hearing Loss: Damage to ear structures.
- Sensorineural Hearing Loss: Damage to the cochlea or auditory nerve.
- Conductive Hearing Loss: Damage to the wave-carrying portions of the ear (pinna, auditory canal, tympanic membrane, ossicles).
- Mixed Hearing Loss: Combination of both.
Diagnosis of Hearing Loss: Rinne Test, Speech in Noise Test, Audiograms (Pure Tone Test).
Interventions for Hearing Loss: Hearing Aids, Cochlear Implants.
Hearing Levels:
- Normal Hearing: 0-20 dB
- Mild Hearing Loss: 21-40 dB
- Moderate Hearing Loss: 41-55 dB
- Moderate to Severe Hearing Loss: 56-70 dB
- Severe Hearing Loss: 71-90 dB
- Profound Hearing Loss: >90 dB
Bioethical Concerns Related to Cochlear Implants: Cost, potential for complete hearing loss, offense to the deaf community.

1.4 Vaccination and Epidemiology

Vaccines activate the immune system to recognize a disease antigen and produce antibodies.
Vaccines can be produced in the laboratory by various methods, including recombinant DNA techniques.
Epidemiologists monitor health populations, track patterns, assist in investigations and design treatment and prevention strategies
Vaccination Definition: Injection of dead, weakened, or modified pathogens to activate the immune system.
- Specialized memory lymphocyte remains to produce Antibodies when exposed to true infection.
Impact of Vaccination: Reduced disease trends.
- Eliminated smallpox and polio.
Methods to Produce Vaccines in the Laboratory: Similar-Pathogen vaccine, Attenuated virus, Killed vaccine, Toxoid vaccine, Subunit vaccine, Naked-DNA vaccine.
* “similar-pathogen” vaccine: Find a virus similar to the one you want to protect against (as cowpox is similar to smallpox), isolate the virus, and inject it “live” into the person being inoculated.
* attenuated virus: Altering the virus enough that it is weakened in the human body. In the case of measles, the virus is adapted to grow in cold environments. The human body is warm enough that cold-loving viruses don’t do well, so the body has time to make antibodies before an infection sets in. After antibodies are present in the body, you are.
* killed vaccine: The virus is killed with heat, radiation, or some other means, then injected dead into your body. The dead virus produces a weak response in the body – not enough for true immunity to set in, which is why boosters are often required.
* Subunit vaccine: Consists of nothing more than a portion of a pathogen - a chunk. A specific “chunk” of virus is chosen for vaccination, and the body recognizes that “chunk” on a pathogen when it encounters it.
* Naked-DNA vaccine: Gene that will produce a protein, is selected for vaccination .This gene is amplified and placed into a vector of double-stranded DNA. This DNA is injected into a bacteria, the bacteria grow and are lysed, and the DNA is extracted for injection into the human.
Recombinant DNA Technology: Modifying DNA using restriction enzymes and bacterial cells to produce vaccines.
- Modifying DNA by adding or removing genes, placing this modified DNA into an organism, and letting that organism replicate.
Epidemiology: The study of disease, and epidemiologists are dedicated medical professionals at the heart of the public health field, monitor the health of populations and search for patterns in disease and treatment.