[Determination of serum semicarbazide-sensitive amine oxidase activity in diabetic retinopathy in type-2 diabetes].
BACKGROUND
Recent data suggest that the copper-containing semicarbazide-sensitive amine oxidase enzyme (SSAO) may play a role in vascular endothelial damage through conversion of certain endogenous monoamines, like methylamine into cytotoxic aldehydes, hydrogen peroxide and ammonia. SSAO is present in various human tissues and in the serum. Elevated SSAO activities have been reported in patients with both types of diabetes mellitus. The purpose of this study was to examine the possible association between serum SSAO activity and the different severity stages of diabetic retinopathy.


METHODS
A prospective study was performed on a defined group of Type 2 diabetic patients (n = 93) compared to non-diabetic control subjects (n = 42). All participants underwent a detailed ocular examination (slit lamp, colour retinal photography, fluorescein angiography) and standard laboratory investigations. Age at diagnosis, duration of diabetes, presence of systemic hypertension, medication and BMI were recorded. Serum SSAO activity was determined by a radiometric procedure using [14C]-benzylamine as substrate.


RESULTS
In the total group of Type 2 diabetic patients SSAO activity (mean +/- SD) was significantly elevated compared to non-diabetic controls (n = 93, 131.72 +/- 53.07 vs. n = 42, 89.56 +/- 26.89 pmol.mg-1 protein.hour-1, p < 0.0001). After dividing patients to four subgroups according to the severity of diabetic retinopathy, serum SSAO activity was significantly higher in patients with high-risk proliferative diabetic retinopathy (n = 16, 166.96 +/- 70.56 pmol.mg-1 protein.hour-1) compared to those without retinopathy (n = 42, 119.54 +/- 50.49 pmol.mg-1 protein.hour-1, p < 0.02).


CONCLUSIONS
The results support the hypothesis that elevated SSAO activity may be involved in the pathogenesis of microvascular diabetic late complications, such as retinopathy. The pharmacological manipulation of SSAO activity might be an interesting new concept for prevention and treatment of diabetic retinopathy.
Dura
Eszter
E
Altalános Orvostudományi Kar, II. sz. Szemészeti Klinika, Semmelweis Egyetem, Budapest. dura@szem2.sote.hu
Mészáros
Zsuzsa
Z
Salacz
György
G
Magyar
Kálmán
K
Romics
László
L
Karádi
István
I
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006631:Amine Oxidase (Copper-Containing) / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000201:enzymology / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000175:diagnosis / Q000201:enzymology* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012663:Semicarbazides / Q000378:metabolism*; D012720:Severity of Illness Index
D012663:Semicarbazides; C010059:carbamylhydrazine; D006631:Amine Oxidase (Copper-Containing)