A patient has symptoms that are characteristic of multiple sclerosis (MS). Which diagnostic tests are likely to be ordered to aid in the diagnosis of this patient?

Choice A rationale

Magnesium plays a role in various cellular functions, including enzyme activity and muscle contraction, but it does not directly inactivate troponin to enable actin and myosin interaction.

Choice B rationale

Sodium is essential for action potential generation and nerve impulse transmission but does not directly influence troponin activity or muscle contraction through actin and myosin bridge formation.

Choice C rationale

Potassium is critical for maintaining cellular resting membrane potential and repolarization of cells but does not play a direct role in inactivating troponin to facilitate muscle contraction.

Choice D rationale

Calcium is the electrolyte that inactivates troponin, allowing actin and myosin to form cross-bridges and contract muscle fibers. Calcium binds to troponin, causing a conformational change that exposes binding sites for myosin on actin filaments.

Choice A rationale

Working with animals is typically done in preclinical trials before phase I studies in humans and is not part of phase III drug evaluation studies.

Choice B rationale

Conducting research to determine the effectiveness of the drug is part of phase II studies. Phase III studies focus more on confirming effectiveness, monitoring side effects, and comparing it to commonly used treatments.

Choice C rationale

Monitoring and observing patients closely for adverse effects is a key responsibility in phase III drug evaluation studies. These studies involve a larger patient population to gather comprehensive safety and efficacy data.

Choice D rationale

Choosing appropriate patients to be involved in the study is primarily the responsibility of researchers and clinicians during the earlier phases of drug development, such as phase I and phase II studies.