Clinical Applications 1  : A very sensitive (83%) and highly specific (96%) diagnostic marker in the evaluation of actual or suspected pheochromocytoma. 2  Drugs commonly employed in the diagnosis or treatment of pheochromocytoma has little effect on the plasma chromogranin A level. 3  To ascertain the source of a tumor.ntroduction : Chromogranin A belongs to the acidic, soluble protein present in the secretory vesicles of neuroendocrine. Immunohistochemical studies have demonstrated that chromogranin A is present in virtually all granulecontaining. endocrine cells and in the great majority of tumors of neuroendocrine origin.
Lenses with the 'G' designation don't have an aperture ring. Aperture has to be set through the camera. AFS lenses have the focusing motor built into the lens. Usually much quieter and faster focusing than regular AF lenses that have the focusing motor in the body and mechanically focus the lens.: The lens has no aperture control ring and is designed to be used with cameras that allow setting the aperture from the camera body. G lenses also provide Distance information to the camera.
Canon EF-S lens mount. The Canon EF-S lens mount is a derivative of the EF lens mount created for a subset of Canon digital single-lens reflex cameras with APS-C sized image sensors. It was released in 2003. Cameras with the EF-S mount are backward compatible with the EF lenses and, as such, have a flange focal distance of 44.0 mm. Such cameras, however, have more clearance, allowing lens elements to be closer to the sensor than in the EF mount. Only Canon cameras released after 2003 with APS-C sized sensors support t