Epstein M, Duncan DC, Fishman LM Characterization of the natriuresis caused in normal man by immersion in water. Clin Sci. 1972 Aug;43(2):275-87.
Epstein M, Miller M, Schneider N Depth of immersion as a determinant of the natriuresis of water immersion. Proc Soc Exp Biol Med. 1974 Jun;146(2):562-6.
Epstein M Renal, endocrine and hemodynamic effects of water immersion in man. Contrib Nephrol. 1984;41:174-88.
Greenleaf JE Physiological responses to prolonged bed rest and fluid immersion in humans. J Appl Physiol Respir Environ Exerc Physiol. 1984 Sep;57(3):619-33. Review.
Katz VL Exercise in water during pregnancy. Clin Obstet Gynecol. 2003 Jun;46(2):432-41. Review.
Katz VL Water exercise in pregnancy. Semin Perinatol. 1996 Aug;20(4):285-91. Review.
Marsál K Obstetric management of intrauterine growth restriction. Best Pract Res Clin Obstet Gynaecol. 2009 Dec;23(6):857-70. doi: 10.1016/j.bpobgyn.2009.08.011. Epub 2009 Oct 24. Review.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.