Fig. 1

Excessive methionine (MET) intake increased the incidence of cerebral aneurysmal rupture. a The plasma homocysteine (Hcy) level in MET-treated rats was significantly higher than in the controls. Plasma Hcy was measured by radioimmunoassay (each group, n = 5). *p < 0.01 vs control rats by Student’s t test (mean ± SD). b The total rupture rate was significantly higher in MET-treated rats (n = 25) than in the controls (n = 19) at 6 and 8 weeks after aneurysm induction. *p < 0.05 vs control rats by Fisher’s exact probability test. c Representative photographs of subarachnoid hemorrhage (SAH) due to the rupture of aneurysms at the anterior communicating artery (AcomA) (left) and the posterior half of the circle of Willis (PW) (right). Aneurysm formations were found after the removal of the blood clot from SAH (lower photographs). The location of aneurysms is indicated by rectangles. White arrows indicate aneurysms. Bars = 2.5 mm. d The incidence of rupture of AcomA and PW aneurysms in MET-treated and control rats