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More than nineteen million Americans carry the factor V gene that causes blood clots, pulmonary embolism, and heart disease.
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
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.
On average, the stomach produces 2 L of hydrochloric acid per day.
Multiple experimental evidences have confirmed that at the molecular level, cancer is caused by lesions in cellular DNA.