An example of MS-DOS's command-line interface, this one showing that the current directory is the root of drive C. MS-DOS (/ËÉmÉsËdÉs/ EM-es-DOSS; acronym for Microsoft Disk Operating System) is a discontinued operating system for x86-based personal computers mostly developed by Microsoft.
Written by: Kierstan Boyd. Nov. 08, 2012. The main symptom of vitamin A deficiency is vision loss and blindness. Vision loss often begins as a problem adjusting to seeing in the dark, or night blindness. People with night blindness do not see well in the dark, but are able to see normally if enough light is present.
If you get too much vitamin A, you can become sick. Large doses of vitamin A can also cause birth defects. Acute vitamin A poisoning usually occurs when an adult takes several hundred thousand IUs of vitamin A. Symptoms of chronic vitamin A poisoning may occur in adults who regularly take more than 25,000 IU a day.