Science has never been constrained by ethics.

The same scientists who cry about ethics, have happily experimented on mice and guinea pigs in their labs, even if it causes the deaths or distress of those little sentient beings.

Mutations/mutatives like Halo's Master Chief and Marvel's Super Soldier serum won't remain sci-fi for much longer, methinks.

former practicing scientist at an institute whose name you would recognize.

The field may not be fully constrained by ethics, which is just a way of saying that the work is done by people and people have varying ethical bounds, but from what I saw many of my colleagues were highly ethics driven.

I remember one Russian colleague who smuggled blood products out of Russia so they could be tested for HIV. Because the Russian government refused to help these patients. The man risked his life to help HIV sufferers.

Ethics is best when matched with courage, if a person is willing to put their life on the line for their beliefs.

Also noting that in the western world, experiments generally need approval of an ethics board before proceeding. That board's sense of ethics might make different judgments than you on, for example, mice experiments, but there is a big difference between "not constrained" and "some of the constraints are different than what I would choose".

where in this case, the ethics boards decided that provided a certain risk/reward barrier is crossed, and that the animals are otherwise treated well, sacrificing mice to improve human health is just fine.

That is an ethics based decision that was debated for a long time. And maybe should continue to be debated, there is real value in your stance that all beings are sentient and this demands a level of care.

And save human life at the same time? Experiments are not just about torturing animals; people spend a lot of time optimizing for experiment design.