1. Cobalamin deficiency and subacute combined degeneration after nitrous oxide anesthesia: A case report 
Sung C. Ahn, DO, Allen W. Brown, MD 
Archives of Physical Medicine and Rehabilitation 
Volume 86, Issue 1, Pages (January 2005)
DOI: /j.apmr
Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

2. Fig 1
Active cobalamin with cobalt in its reduced form (Co+). N2O inactivates cobalamin by irreversibly oxidizing cobalt to the Co++ and Co+++ forms.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

3. Fig 2
Cobalamin (B12) is converted to methylcobalamin (MB12) in the cytoplasm where it binds to methionine synthetase (MS). N2O inactivates methylcobalamin plus methionine synthetase, preventing the catalytic conversion of N5-methyltetrahydrofolate (MTHF) and homocysteine to 5-methylenetetrahydrofolate (THF) and methionine. The other cobalamin-dependent coenzyme, deoxyadenosylcobalamin (DB12), catalyzes reactions important for carbohydrate and lipid synthesis. Abbreviation: CoA, coenzyme A. (Used by permission, adapted from Flippo TS, Holder WD. Arch Surg 1993;128:1391–95, figure p AMA).
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions