*in case you are curious, my thesis was differing techniques of "invisible" suturing and their response to collagen growth in the wound underlayer. My roomamte at school did it on a specific disorder that makes you hair painful. All the big, neat stuff has been done.....
You have touched on a really fascinating topic -- whether all the big neat stuff has been done, or whether the medical system is structured to tackle the "big stuff". Is there a forum within apneaboard.com for off topic subjects? How can this discussion move there? Are you interested in pursuing?
I'd always taken for granted that big medical questions were beyond the reach of rigorous science (too much variability, too many ethical constraints), but in the last decade I've become convinced that important "big questions" can be done scientifically if only the medical system were structured differently. My thinking: in physics, in the US at least, there is plenty of money to fund promising physicists and big programs. My son got multiple "full ride" PhD program offers from great schools; his wife had to fund her MD in full. Her indebtedness obviously constrained her later choices. For the big questions large numbers of physicists can be brought together to work in concert on relatively narrow questions, with tight academic standards always maintained, until the question or questions are answered beyond any reasonable doubt (9 sigma!). Long term funding is not impossible. (I recently toured a "gravity wave detection facility" that has been funded for more than a decade, even though without success.) As you may have intended to suggest, in medicine, the questions are either very small (and done well) or more grandiose (and generally scientifically very poor). How can it be that something as observable and examinable as the obesity epidemic (excessive adipose tissue growth) cannot already be explained in great detail? It is not an issue of money; the total money within the medical system dwarfs the money available to physics. It seems to me only that the medical structure has not grown to utilize scientific inquiry at such a large scale.
Well, before this gets moved off topic, the answer is: research is so wide and differing in the medical world that all your questions are either being looked at or will be looked at by someone or some groups somewhere. There isn't a day that I don't get tons of new papers sent to me (thank goodness now electronically - I was so swamped with paper versions before I had to rent extra space to archive them), so big ans small questions are being gone at. It only needs someone to ask the question and soon enough, tons of people are looking for answers. Research medicine is a huge branch of the practice, maybe as big as active medicine, so there is a huge scope. Teaching hospitals have the condition of many of their staff that they devote some time to research as well as teaching and medicine. What the limit is is our imperfect understanding of the complex thing the human body and disease is. Look at cancer - first we thought it was strictly environmental, then we learned about the genetic properties, now we are learning about viral properties - there are so many complex questions to answer about something like cancer, or heart disease, or other areas, that it will be a long time before we perfectly understand, or even more than superficially understand the incredible organism that we are. That is one of the reasons we have to keep going to continuing education courses and requalifying. And that is what makes it all so interesting. Always new understandings and better models.