21.   Both strains of mice develop insulin resistance, the so-called pre-diabetes state that often afflicts fat people, Leibel said.

22.   -- HIV has proven to be a formidable foe of science, developing resistance to anti-viral drugs.

23.   -- So far, even ardent environmentalists acknowledge that insects have not developed resistance to modified pesticides, as they expected.

24.   A certain number of squirrels will die, some will develop a resistance and some will be naturally immune.

25.   A crucial question is whether HIV could develop resistance to the drugs.

26.   A challenge for researchers is to make it easier for patients to adhere to these drug regimens, or HIV will swiftly develop resistance to them.

27.   A majority of these patients were beginning to develop resistance to the medications.

28.   A major difficulty with existing drugs is that they lose effect when HIV develops resistance to them.

29.   But all work in the same ways as existing drugs, so patients who have developed resistance to standard drugs may also be resistant to these.

30.   But doctors are concerned that the bacteria that cause pneumonia might soon develop resistance to most common antibiotics.