Abstract
Purpose: :
To analyse the level of diadenosine tetraphosphate Ap4A in tears of subjects with dry eye associated to systemic pathologies, such as Sjögren syndrome and congenital aniridia.
Methods: :
Nine subjects, diagnosed with Sjögren Syndrome, and fifteen subjects diagnosed with congenital aniridia, participating in the present study were invited to fill a Symptom Questionnaire. The tear secretion was measured and collected by Schirmer I test. The strips were placed in Eppendorf tubes containing 500 µL of ultrapure water and submitted to Sep-Pak Accell QMA chromatography. All the tear samples were then processed by High Pressure Liquid Chromatography (HPLC) . The system was equilibrated with a mobile phase consisting of 10 mM KH2PO4, 2mM tetrabutyl ammonium, 15 % acetonitrile, pH, 7.5. with a NovaPak C18 column. The control group were 37 subjects without symptoms and a normal values of Schirmer test and BUT
Results: :
Sjögren Syndrome patients presented a values of Schirmer test of 4.12±3.90 mm. This patients were organised in two groups, those individuals presenting normal tear production and those presenting low tear production. The concentration of Ap4A in normal tear production patients were 0.42±0.01 µM. Those patients presenting Sjögren Syndrome and low tear production presented Ap4A concentration of 4.57 ± 1.20 µM. Patients with congenital aniridia were organised by age. The values of Schirmer I test for patients with congenital aniridia under 10 years old were 20.6 ± 9.4 mm, 12.6±9.3 mm for patients between 10 and 25 years old and 13.6±8.3 mm for the patients between 25 and 50 years of age. Only a patient was older than 50 years old, this patient presenting Schirmer values of 1.25 mm. The concentrations observed for Ap4A were 11.8±2.3 µM and 21.5±1.7µM, 29.5±1.8 µM and 196.1±3.3 µM, for each group. Control patients presented values of diadenosine tetraphosphate of 0.107 ± 0.048 µM.
Conclusions: :
Patients with this systemic pathologies, present abnormally elevated values of Ap4A indicating that this compound could be used as a marker for the dry eye severity.
Keywords: cornea: tears/tear film/dry eye • pathology: human • adenosine