Esophageal pH monitoring developed a dependable external reference electrode. Using this technique to monitor esophageal acid exposure patients for periods up to 24 hours, DeMeester and Johnson were able to identify the most important parameters of esophageal acid exposure, and they developed a composite pH score to quantify gastroesophageal reflux. The initial 24-hour pH studies required hospitalization until the introduction of microcircuits in the 1980s that allowed portable esophageal pH monitoring in an outpatient setting. Gastroesophageal reflux disease (GERD) is a common disease in western countries. In the United States, 7% of the population experiences heartburn daily and 44% at least once a
Bohemic acid under neutral or slightly basic pH conditions, and the fats and oils are removed by washing with petroleum ether. Chromatographical separation, in addition to the antibiotics pyrromycin and cinerubin A and B, reveals several individual components of bohemic acid, including alcindoromycin, bohemamine, collinemycin, marcellomycin, mimimycin, musettamycin, rudolphomycin and schaunardimycin. Their names originate from the characters Alcindoro, Colline, Marcello, Mimì, Musetta, Rodolfo (Rudolph) and Schaunard of the Puccini opera "La Bohème", and the acid itself and the bohemamine component carry the name of the opera. The suffix "-mycin" is conventionally added to indicate antibiotics derived from actinobacteria or fungi. The individual