pharma matter

                                                           1. INTRODUCTION 1.1 Stem cells In the past few years, stem cells have generated great excitement among researchers, physicians, patients, the media and the general public. These rare and powerfully therapeutic cells are immature “master” cells that can renew themselves and develop into a variety of cell types. Most stem cells occur in the bone marrow, although they have been identified in other organs, as well. Marrow stem cells produce all of the body’s oxygen-carrying red blood cells, infection-fighting white cells and the platelets necessary for clotting. (20) 1.2 Stem cell transplant A stem cell transplant is a complex procedure to replace...

 Pepsin terms a small group of gastric proteases that are active in acidic environments with a pH between 1 and 5. Its name comes from the Greek word pepsis, which means to digest. The most studied and commercially available form of pepsin is porcine pepsin A, isolated from the gastric mucosa of a pig. Pepsin is not directly formed after translation of its coding mRNA, but instead begins as a zymogen, or an inactive precursor. This preliminary, inactive form that is initially translated is called pepsinogen. The activation of pepsinogen is accomplished by lowering the pH below 4.5, which leads to a cascade of changes in bond structure, as shown in Figure 2 below, and yields the enzyme pepsin. The first step is reversable, however once the protein has progressed beyond step II, the protein cannot revert back to the inactive pepsinogen. (James and Sielecki, 1986) Figure . Proposed steps in the activation of pepsinogen into pepsin. Note that pepsin ends up with 44 amin...