Nasal Potential Difference (NPD)
A test of salt transport in the cells lining the nose. Transport of ions such as sodium and chloride creates an electrical potential difference across the epithelium (or lining) of the airway. This nasal potential difference (NPD) can be measured in patients by placing an electrode on the lining of the nose. The NPD can be used as a diagnostic test for CF.

Ooctye
An egg from a frog that is used in laboratory studies that investigate ion channels.

Phase I Trial
A study that investigates the safety of a new drug or treatment.

Phase II Trial
A study that investigates both the safety and effectiveness of a new drug or treatment.

Phase III Trial
A large study that determines if a new drug or treatment is effective and should be approved for use by patients.

Phase IV Trial
A study that is usually done after a drug has been approved for use. This type of study is used to determine the safety of a drug in a large group of people. Everyone in the study uses the drug and a placebo is not used.

Placebo
A substance used in a clinical research trial that has no active ingredients. The effect of a study drug is usually compared to a placebo.

Principal Investigator (PI)
Person who is responsible for a research study.

Protocol
The plan for a clinical trial that includes how medications will be given and what testing will be perfomed.

Pseudomonas aeruginosa
Pseudomonas aeruginosa (P. aeruginosa) is a bacteria that is important because it can chronically infect, or colonize, the lungs of CF patients. P. aeruginosa is resistant to many antibiotics and capable of surviving in conditions that few other organisms can tolerate. P. aeruginosa is often encountered in hospital and clinical settings where it is a major cause of hospital acquired, or nosocomial, infections, but it can also be found in many other places that are readily accessible to patients. P. aeruginosa thrives in places with a great deal of moisture. The bacteria rarely causes infection in healthy individuals, but in CF patients it can cause increased cough and sputum production, weight loss, decreased lung function, and fatigue or malaise. Nearly 70 percent of patients with CF are chronically infected with P. aeruginosa bacteria. Antibiotic therapy is usually aimed at reducing the amount of chronic infection.

Pulmonary Function Testing (PFT)
Evaluation of lung function by measuring the amount of air a patient is able to inhale and exhale. The patient is asked to perform several sequences of maximal inspiration and expiration, and a computer measures the amount of air going into and out of the lungs. The computer can then estimate the capacity and function of the lungs as compared to healthy individuals of the same size.

Randomization
The process of assigning people into groups for a study so that each person has an equal chance to be given the study treatment. Randomization assures that the people in each group will have similar characteristics.

Research Coordinator (RC) or Study Coordinator (SC)
Person who conducts a research study. Responsibilities may include obtaining informed consent, keeping accurate records and dispensing medications and making measurements.

Subject
A research study participant.