Sugars including erythronic and threonic acids in human aqueous humour.
OBJECTIVE
Sugars in the aqueous humour of the eye serve both as a source of nutrients to the lens and other anterior ocular tissues, and potentially as an indicator of waste products from these tissues. In this work we intended to measure the levels of sugars in human blood and aqueous humour from cataract patients with and without diabetes. After initial results we decided to identify an unknown sugar component.


METHODS
Sugars were measured by hplc. The unknown sugar peak was identified by gas chromatography/mass spectrometry


RESULTS
Very little fructose and sorbitol were found. Glucose levels were higher in both blood and aqueous from diabetic patients. During these analyses we found a major component that did not correspond to any sugar reported previously in aqueous humour. This was identified as a mixture of threonic and erythronic acids.


CONCLUSIONS
Glucose levels increase in human aqueous humour in diabetes without markedly raised levels of sorbitol or fructose. Erythronic and threonic acids are normal components of aqueous humour and blood. They may be derived from glycated proteins or from degradation of ascorbic acid.
University of Oxford Nuffield Laboratory of Ophthalmology United Kingdom Oxford, johnharding@ee.ox.ac.uk.
J J
JJ
Harding
P C
PC
Hassett
K C
KC
Rixon
A J
AJ
Bron
D J
DJ
Harvey
D000368:Aged; D000369:Aged, 80 and over; D001082:Aqueous Humor / Q000378:metabolism*; D002087:Butyrates / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002851:Chromatography, High Pressure Liquid; D003920:Diabetes Mellitus / Q000378:metabolism; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D012016:Reference Values
D002087:Butyrates; C121691:erythronic acid; C011369:threonic acid