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To the Editor:
—I cannot agree with Dr. Sidney Lerman's statement in his article "Carbohydrate Metabolism in the Rat Lens as Related to the Age of the Animal" (Arch. Ophthal. 65:181, 1961) that the TPNH/TPN ratio "reflects the activity of the shunt." A direct relationship has never been established between the shunt mechanism and the TPN ratio. It is conceivable that a tissue possessing a very low shunt activity as well as a sluggish mechanism to reoxidize TPNH may exhibit a high TPNH/TPN ratio. On the other hand, a tissue with a very active shunt pathway and a very active mechanism for the reoxidation of TPNH would have a low ratio. It is difficult to see, therefore, how the TPNH/TPN ratio can serve as an index of shunt activity.I would like to point out certain aspects of the data not referred to by the author, which further strengthen his
Kinoshita JH. THE AGING RAT LENS. Arch Ophthalmol. 1961;66(3):447-448. doi:10.1001/archopht.1961.00960010449023