Aphthous stomatitis caused by a reduction in numbers of CD4+ T cells may be implicated in RAS-type ulceration in HIV infection. The thickness of the mucosa may be an important factor in aphthous stomatitis. Usually, ulcers form on the thinner, non-keratinizing mucosal surfaces in the mouth. Factors which decrease the thickness of the mucosa increase the frequency of occurrence, and factors which increase the thickness of the mucosa correlate with decreased ulceration. The nutritional deficiencies associated with aphthous stomatitis (Vitamin B12, folate, and iron) can all cause a decrease in the thickness of the oral mucosa (atrophy). Local trauma is also associated
History of medicine in the Philippines Rodrigo de San Miguel's "Manual de Medicina Domestica" (Manual on Domestic Medicine), and Fr. Manuel Vilches' "Manuel del Mediquillo Visaya" (Manuel of the Visayan Traditional Healers). Philippine National Artist and painter Carlos "Botong" V. Francisco recorded and depicted the history of medicine in the Philippines by creating four mural-like four-panel oil paintings collectively titled "The Progress of Medicine in the Philippines", which traced the practice of medicine from the times of the "babaylans" ("medicine men and women") up to a period in the modern-day era. The first painting depicts pre-colonial medicine, the second portrays medicine during the Spanish colonial period,