Sunday, July 11, 2010

Cluade Bernard

Claude Bernard was born on July 12, 1813, in Saint-Julien, a small village near Villefranche-sur-Saone, in eastern France. His father owned a small estate that produced wine. A bright child, the village cure took him under his wing, teaching him Latin and making him a choir boy. Afterwards he went to the Jesuit college in Villefanche. He briefly went to the university in Lyon, but due to financial reasons he was forced to take a job as a pharmacist's assistant, at first working for only room an board.

Bernard's ambitions were not initially for medicine, but for literature. He wrote several plays and had one successfully performed. In 1834, at 21, using the proceeds of his play, Bernard went to Paris, with a five act history he had written. In Paris, he showed the play to Saint-Marc Girardin, a literary critic, professor at the Sorbonne, and at the time the last word on French letters. Girardin, told Bernard that he should study medicine and not write plays. Bernard threw himself into the study of medicine and in 1839 he was appointed an interne at the Hotel Deiu. This position allowed to come into contact with Francios Magendie, the experimental physiologist. In 1843 Bernard finished his doctorate with a thesis on gastric juice and the role it plays in digestion which won him a prize from the Academie des Sciences for experimental medicine in 1850.

After the initial success of his thesis, in which he showed that complex carbohydrates were broken down by gastric secretions, Bernard wanted to continue his research to determine the fate of three basic nutritional components of food (sugars, fats and proteins) in the body. Using a dog fed only protein, he found that there was sugar in the dog's liver. This led him to the conclusion that the liver synthesizes sugar. Additionally he discovered that after the liver had been washed out and left to sit for a while, an additional amount of sugar was released. This was the discovery of glycogen, Bernard's most famous discovery.

Glycogen is the way the body stores carbohydrates for later use and it is found in the liver and in muscle tissues. After eating, when the body has an excess of glucose, glycogen is stored for later use. Insulin, a hormone produced by the pancreas, stimulates the cells of the body to uptake glucose and store it as glycogen. When the amount of glucose in the blood stream drops, glucagon is produced by the pancreas which causes the glycogen in the liver to be broken down and released into the blood stream. In this way the body is able to maintain a constant amount of glucose in the blood stream.

Bernard's other major discovery was the effect of vaso-motor nerves. Initially investigating the effect of heat on the body he discovered the vaso-dilating and vaso-constricting affect of the nervous system.

In 1847 Bernard was appointed Magendie's deputy and in 1855 he succeeded his mentor as professor. In 1864 he was introduced to Napoleon III, who created for him two well supplied laboratories. In 1869 he was made senator, a position he lost the next year with the fall of the Emperor. Bernard had little interest in politics and continued his research. Though he was honored throughout the world for his discoveries, he was estranged from his family. His wife and daughters, ashamed of the vivisections he used in his research, left him.

Bernard died on February 10, 1878.


Foster, Sir Michael; Claude Bernard; Longmans, Green, and Co.; 1899

Anonymous; Heroes of Medicine: Claude Bernard; The Practitioner; 63(1899)185-190

Claude Bernard, Wikipedia Entry

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