In another episode of TNG to feature a deadly disease and the Enterprise warping in to the rescue (a reliable Trek cliché not avoided in the first two seasons of TNG, to be sure), Dr. Pulaski attempts to find a cure to a disease that is causing rapid aging on a Federation space station that's perhaps too ironically named Darwin Station. (The disease has already killed the crew of an entire starship.)
In terms of character, I did appreciate the way the story establishes Pulaski as a strong-willed personality willing to go to the mat for her point of view and for her patients, even if she must risk herself. She stands up to Picard and argues the merits, even if it means Picard doesn't get to finish a sentence. Picard, always the final authority, but ever the diplomat and patient listener, calls her on her penchant for interrupting without making a big deal about it.
Pulaski's medical safeguards fail, and in attempting to find the cure in the station's genetically engineered children, she ends up infected herself. (The children are actually the cause of the disease because of their genetically manipulated immune systems, which create the disease without being susceptible to it.)
I find it very hard to be moved by an episode like "Unnatural Selection," mainly because the episode is too mired in procedure and arbitrary pseudoscientific details rather than characters or plot. Also, diseases that make people prematurely old are not very interesting. In terms of its sci-fi procedural approach, I suppose it's worth noting that the episode makes sense for most of the way and the pieces fit together to make a workable puzzle — that is, until the end, where the transporter is used to magically restore Pulaski's DNA (and cure the rest of the station's residents). This is a perfect example of the tech solving the plot arbitrarily rather than any sort of legitimate dramatic payoff. But then that's often the problem with tech medical shows like these.