Acetyl group known as paracetamol), and acetylsalicylic acid (better known as aspirin). The introduction of an acetyl group into a molecule is called acetylation. In biological organisms, acetyl groups are commonly transferred from acetyl-CoA to other organic molecules. Acetyl-CoA is an intermediate both in the biological synthesis and in the breakdown of many organic molecules. Acetyl-CoA is also created during the second stage of cellular respiration, the Krebs Cycle, by the action of pyruvate dehydrogenase on pyruvic acid. Histones and other proteins are often modified by acetylation. For example, on the DNA level, histone acetylation by acetyltransferases (HATs) causes an expansion of
Hippocrates 129 to AD 200. Galen perpetuated Hippocratic medicine, moving both forward and backward. In the Middle Ages, the Islamic world adopted Hippocratic methods and developed new medical technologies. After the European Renaissance, Hippocratic methods were revived in western Europe and even further expanded in the 19th century. Notable among those who employed Hippocrates' rigorous clinical techniques were Thomas Sydenham, William Heberden, Jean-Martin Charcot and William Osler. Henri Huchard, a French physician, said that these revivals make up "the whole history of internal medicine." According to Aristotle's testimony, Hippocrates was known as "The Great Hippocrates". Concerning his disposition, Hippocrates was first