SAMe is the universal methyl donor and is used for DNA methylation and to make phospholipid membranes, choline, sphingomyelin, acetylcholine, and other neurotransmitters. In mitochondria
The enzymes that use B12 as a built-in cofactor are methylmalonyl-CoA mutase (PDB 4REQ) and methionine synthase (PDB 1Q8J).The metabolism of propionyl-CoA occurs in the mitochondria and requires Vitamin B12 (as adenosylcobalamin) to make succinyl-CoA. When the conversion of propionyl-CoA to succinyl-CoA in the mitochondria fails due to Vitamin B12 deficiency, elevated blood levels of methylmalonic acid (MMA) occur. Thus, elevated blood levels of homocysteine and MMA may both be indicators of vitamin B12 deficiency. Adenosylcobalamin is needed as cofactor in methylmalonyl-CoA mutase—MUT enzyme. Processing of cholesterol and protein gives propionyl-CoA that is converted to methylmalonyl-CoA, which is used by MUT enzyme to make succinyl-CoA. Vitamin B12 is needed to prevent anemia, since making porphyrin and heme in mitochondria for producing hemoglobin in red blood cells depends on succinyl-CoA made by vitamin B12. Absorption and transport
Inadequate absorption of vitamin B12 may be related to coeliac disease. Intestinal absorption of vitamin B12 requires successively three different protein molecules: haptocorrin, intrinsic factor and transcobalamin II. See also
Methylcobalamin
Hydroxocobalamin
Adenosylcobalamin
Cobalamin biosynthesis

References
External links
"Cyanocobalamin". Drug Information Portal. U.S. National Library of Medicine.
Mitoxantrone (INN, BAN, USAN; also known as Mitozantrone in Australia; trade name Novantrone) is an anthracenedione antineoplastic agent. Uses
Mitoxantrone is used to treat certain types of cancer, mostly acute myeloid leukemia. It improves the survival rate of children suffering from acute lymphoblastic leukemia relapse.The combination of mitoxantrone and prednisone is approved as a second-line treatment for metastatic hormone-refractory prostate cancer. Until recently this combination was the first line of treatment; however, a combination of docetaxel and prednisone improves survival rates and lengthens the disease-free period.Mitoxantrone is also used to treat multiple sclerosis (MS), most notably the subset of the disease known as secondary-progressive MS. In the absence of a cure, mitoxantrone is effective in slowing the progression of secondary-progressive MS and extending the time between relapses in both relapsing-remitting MS and progressive-relapsing MS.

Side effects
Mitoxantrone, as with other drugs in its class,  may cause adverse reactions of varying severity, including nausea, vomiting, hair loss, heart damage and immunosuppression, possibly with delayed onset. Cardiomyopathy is a particularly concerning effect as it is irreversible; thus regular monitoring with echocardiograms or MUGA scans is recommended for patients. Because of the risk of cardiomyopathy, mitoxantrone carries a limit on the cumulative lifetime dose (based on body surface area) in MS patients. Mechanism of action
Mitoxantrone is a type II topoisomerase inhibitor; it disrupts DNA synthesis and DNA repair in both healthy cells and cancer cells by intercalation between DNA bases. It is also classified as an antibiotic. See also
Pixantrone, a mitoxantrone analogue under development
Losoxantrone

References
External links
"Mitoxantrone". Drug Information Portal.