1804, Nicolas Theodore de Saussure (1767-1845), showed via quantitative measurements that the carbon in plants came almost entirely from carbon dioxide and that the rest of a plant (aside from mineral) was made up of water (1).

1816, Francois Magendie (1783-1855), tested the idea of a monotonous diet of water and some food (non-nitrogenous) on animals (dogs).

1817, J. Pelletier (1788-1842) and J. B. Caventou (1795-1877), isolated chlorophyll.

1824, William Prout (1785-1850), showed that the acid of gastric juice was muriatic acid (2).

1827, William Prout (1785-1850), developed the idea of three classes of foodstuffs – the saccharine, the oily, and the albuminous.

1835, Theodore Schwann (1810-1882), determined that gastric juice contained a catalyst he called pepsin to breakdown food.

1842, Justus von Liebig (1803-1873), applied his theories of chemistry to animal and human physiology (3).

1845, J. R. Meyer (unknown), plants fixed the energy of sunlight and served later to supply energy to humans.

1845, Louis Mialhe (1807-1886), obtained the enzyme ptyalin from saliva.

1846, Claude Bernard (1813-1878), observed the breakdown of starch, fats, and protein via pancreatic juice.

1849, A. A. Berthold (1803-1861), first experimental proof of endocrine function by transplanting testicular tissue in fowls and showed that he could thus prevent the effects of caponization.

1852, Friedrich Bidder (1810-1894) and Carl Schmidt (1822-1894), confirmed Prout’s announcement on hydrochloric acid in the stomach. Clearly showed the effect of food on the respiratory quotient of animals.

1857, Claude Bernard (1813-1878), isolated glycogen from the liver.

1865, Carl Voit (1831-1908), showed that combination with oxygen was not the first step in energy production, but that a large number of intermediaries were formed from the original food before the final union with oxygen occurred.

1866 – 1873, Carl Voit (1831-1908) and Max Pettenkofer (1818-1901), published papers on animal metabolism under different conditions.

1876, Willy Kuhne (1837-1900), completed the work of Bernard by studying the action of pancreatic juice on proteins and isolating trypsin. Also introduced the phrase enzyme.

1877, E, F, W, Pfluger (1829-1910), proved Voit’s theory on energy metabolism by showing that a rabbit breathing quietly or by forced respiration consumed the same amount of oxygen.

1881, Nikolai Ivanovich Lunin (1854-1937), showed that a small amount of milk must be added to the purified diets of carbs, fats, and proteins in order to keep experimental animals alive.

1883 – 1884, Max Rubner (1854-1932), announced isodynamic law which stated that the three types of foods – carbohydrate, fats, and proteins – were equal in calorific value. Later motified by Rubner with the specific dyanamic action of foods.

1889, C. E. Brown-Sequard (1817-1894), injected testicular extracts into various subjects (including himself) to introduce the idea of a chemical mechanism for control of important processes.

1889, Joseph von Mering (1849-1908) and Oscar Minkowski (1858-1931), showed that the removal of a dog’s pancreas caused a sharp rise in blood sugar.

1890, Emil Fischer (unknown), studies of the structures of purines and polypeptides opened the way for an understanding of nitrogen metabolism.

1895, George Oliver (1841-1915) and Edward Albert Sharpey Schafer (1850-1935), obtained extract of the adrenal gland that had a powerful effect on raising blood pressure.

1897, Eduard Buchner (1860-1917), obtained an extract of yeast that showed fermenting power – ending the debate between “unorganized ferments” and enzymes by realizing that both are enzymes.

1901, Gerrit Grijns (1865-1915), first correctly explained beriberi as a deficiency disease.

1901, Jokichi Takamine (1854-1922), isolated adrenaline and epinephrine (the first isolation of a hormone).

1902, William Maddock Bayliss (1860-1924) and Ernest Henry Starling (1866-1927), discovered secretin (the hormone that stimulates the flow of pancreatic juice).

1905, William Maddock Bayliss (1860-1924), suggested the name hormone.

1907, Axel Holst (1861-1931) and Theodore Frolich (1871-1953), experimentally extended the concept of deficiency diseases to guinea pigs.

1912, Casimir Funk (1884-1967), suggested that beriberi, scurvy, and pellagra were diseases that required the presence of organic nitrogenous bases in the diet for prevention (4).

1914, Edward Calvin Kendall (1886-1972), isolated the hormone thyroxine (5).

1915, E. V. McCollum (1879-1967), showed that rats required at least two substances in the diet – “fat-soluble A” and “water-soluble B”. These were later called vitamin A and B.

References

(1). (1). H.M. Leicester. The Historical Background of Chemistry, Dover Publications, Inc., New York, USA, (1971) pp. 220-242.

(2). http://en.wikipedia.org/wiki/William_Prout , accessed 6 April, 2015.

(3). http://en.wikipedia.org/wiki/Justus_von_Liebig , accessed 6 April, 2015.

(4). http://en.wikipedia.org/wiki/Casimir_Funk , accessed 6 April, 2015.

(5). http://en.wikipedia.org/wiki/Edward_Calvin_Kendall , accessed 6 April, 2015.

The cyclotron is a particle accelerator that uses an electromagnet and vacuum environment to take an initial voltage and amplify it several times and shoot out particles. It was invented by Ernest Lawrence in 1932 and he was awarded the Nobel Prize in physics for this invention in 1939 (1). Lawrence was said to have initially shot “every available projectile at every available target” in the hope of breaking into and shattering the nuclei of every atom (2). Commonly used projectiles included protons, helium nuclei, as well as deuterons (the nucleus of deuterium atoms). In 1935 Lawrence shot deuterons against the element lithium and obtained helium. Jean and Irene Joliot seemed to have discovered the phenomena of artificial radioactivity by shooting protons, sped up to 600,000 volts, at lithium fluoride crystals. They saw visual flashes of helium atoms striking a special zinc screen. Similarly, Lawrence’s lab discovered 120 artificially produced radioactive substances. One of the more interesting of these was radioactive sodium with a half-life of 15 hours. Radioactive sodium produces gamma rays with energies close to 5.5 million volts, which is almost three times the penetrating power of the gamma rays given off by decaying radium. Radioactive sodium was used in cancer therapy as a substitute for x-rays and radium as well as being used as a radioactive tracer for medical research (2).

References

(1). http://en.wikipedia.org/wiki/Cyclotron , accessed 4 April, 2015.

(2). B. Jaffe. Crucibles: The Story of Chemistry, Dover Publications, Inc., New York, USA, (1976) pp. 265-282.