ABSTRACT
Superoxide radicals are associated with the development of many severe diseases, such as cancer. Under nonpathogenic conditions, the natural enzyme superoxide dismutase (SOD) regulates the intracellular superoxide concentrations, but nearly all tumor tissues show reduced SOD levels. Selective imaging in early progression stages remains a key requirement for efficient cancer diagnosis and treatment. Magnetic resonance imaging (MRI) as a noninvasive tool with high spatial resolution may offer advantages here, but MRI contrast agents exhibiting a redox-triggered change in the image contrast towards superoxide radicals have not been reported so far. Here we show that manganese oxide (MnO) nanoparticles (NPs) exhibit an intrinsic SOD-like activity, which is higher than that of the native Mn-dependent SOD. In addition, MnO NPs significantly enhance the MRI contrast when exposed to superoxide radicals, making them responsive MRI contrast agents for the treatment and imaging of cancer cells with reduced SOD levels.
ABSTRACT
The Army Weight Control Program is a comprehensive, multidisciplinary, and mandated approach to weight control, designed to assist, educate, and motivate overweight individuals to reach their ideal body weight. The program objective is to ensure that Army personnel are able to meet the physical demands of their duties under combat conditions and is based on the assumption that the individual is ultimately responsible for exhibiting high standards of professional appearance. The history and the program philosophy are described. The Army Weight Control Program utilizes height-weight tables as an initial screen, followed by skinfold measurements, to identify overweight soldiers. Individuals who exceed established age and sex adjusted body fat standards (20% to 26% for men and 28% to 34% for women) and who do not have a pathological cause for their obesity are enrolled in the mandatory Army Weight Control Program. Entry into the program results in the withholding of favorable personnel actions. Noncompliance with established monthly weight-loss goals for a period of 6 months may result in separation from the Army. The rationale for the procedures and the methodologies of the program are reviewed and discussed. It is concluded that studies are required to evaluate the effectiveness of mandatory weight-control programs.
