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For about 100 years, scientists thought that peptic ulcers were caused by stress, spicy food, and alcohol. Later, researchers added stomach acid to the list of causes and began treating ulcers with antacids. Now it is known that peptic ulcers are predominantly caused by Helicobacter pylori, a spiral-shaped bacterium that normally exist in the stomach.
Aspirin is the most widely used drug in the world. It has even been recognized as such by the Guinness Book of World Records.
Dogs have been used in studies to detect various cancers in human subjects. They have been trained to sniff breath samples from humans that were collected by having them breathe into special tubes. These people included 55 lung cancer patients, 31 breast cancer patients, and 83 cancer-free patients. The dogs detected 54 of the 55 lung cancer patients as having cancer, detected 28 of the 31 breast cancer patients, and gave only three false-positive results (detecting cancer in people who didn't have it).
Fewer than 10% of babies are born on their exact due dates, 50% are born within 1 week of the due date, and 90% are born within 2 weeks of the date.
As the western states of America were settled, pioneers often had to drink rancid water from ponds and other sources. This often resulted in chronic diarrhea, causing many cases of dehydration and death that could have been avoided if clean water had been available.
![(A) The structure of a neuron, showing the dendrites, nerve cell body, and axon. (B) Photomicrograph](https://biology-forums.com/gallery/47/medium_14755_27_08_12_4_56_11_821215.jpeg)
![The appearance of different types of tissues-muscle, epithelial, nervous, connective-and their locat](https://biology-forums.com/gallery/47/medium_14755_16_09_12_5_52_12_87441522.jpeg)