TCB II: 4247kDa protein Essential protein in the delivery of vitamin B12 to cells and tissues The production site of TCB II is primarily hepatocytic, and secondarily endothelial, monocytic and intestinal Functions of vitamin B12: B12 acts as a cofactor for two key enzymatic reactions: Methionine Synthase (cytoplasm): Converts homocysteine methionine Requires methylcobalamin Supports DNA synthesis via the folate cycle (regenerates tetrahydrofolate) Methylmalonyl-CoA Mutase (mitochondria): Converts methylmalonyl-CoA succinyl-CoA Requires adenosylcobalamin Involved in fatty acid and amino acid metabolism Elevated vitamin B12 (hypervitaminemia B12) While vitamin B12 deficiency is commonly discussed, elevated serum B12 (hypercobalaminemia) is less common and often overlooked or misinterpreted
C max , peak concentration of drug in plasma
A 25 to 27 gauge needle is appropriate, as it minimizes discomfort and is sufficient for penetrating the subcutaneous layer without reaching the muscle
Compliance with ethical standards Clinical Trials Registry: CTRI/2021/01/030204
Todd, at the University of Cambridge, used the LLD assay to extract the anti-pernicious anemia factor from liver extracts, purify it, and name it vitamin B 12