The Law of Conservation of Mass dates from Antoine Lavoisier's 1789 discovery that mass is neither created nor destroyed in chemical reactions. In other words, the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction.
Antibiotic Gentamicin, when mixed with DePuy Orthopaedics bone cement products, may weaken the bond between cement and bone in joint replacement patients, and cause the prosthetic to slide off of the bone after the patient has suffered a great deal of pain and immobility.
The antibiotic penicillin works by keeping a bacterium from building a cell wall. Bacteria and human cells also differ in the structure of their cell membranes and the machinery they use to build proteins or copy DNA. Some antibiotics dissolve the membrane of just bacterial cells. Others affect protein-building or DNA-copying machinery that is specific to bacteria.