thromboxane-b2 and Retinal-Vein-Occlusion

Retinal vein occlusion is a major cause of ocular morbidity. The precise mechanism leading to thrombosis in retinal vein occlusion has not yet been clearly elucidated. Several risk factors have been identified, including hypertension diabetes, history of cardiovascular disease, hypercholesterolemia, hyperhomocysteinaemia, increased ocular pressure and glaucoma. Although thrombus formation in the vein plays a significant role in the onset of retinal vein occlusion, the relationship between platelet aggregation and retinal vein occlusion remains to be clarified.. In the present study the platelet response to thrombin in a selected group of retinal vein occlusion patients was investigated. Retinal vein occlusion patients were compared to a group of healthy subjects matched for age, sex, clinical and metabolic characteristics. In resting and activated platelets of both groups of subjects total protein tyrosine phosphorylation, p38MAPK and cytosolic phospholipase A(2) phosphorylation, arachidonic acid release, intracellular calcium levels, thromboxane B(2) and superoxide anion formation were measured.. Results show that platelets of patients were more responsive to thrombin than healthy subjects. In resting or in thrombin stimulated platelets of patients total protein tyrosine phosphorylation, p38MAPK and cytosolic phospholipase A(2) phosphorylation were increased. Also arachidonic acid release, thromboxane B(2) and superoxide anion formation were higher in patients than in healthy subjects. In addition intracellular calcium rise induced by thrombin was increased in patients.. Altogether data suggest that platelet hyperaggregability inducing thrombus formation might be an important factor in the onset and/or development of retinal vein occlusion.

Topics: Aged; Arachidonic Acid; Blood Platelets; Case-Control Studies; Cytosol; Female; Humans; Male; Middle Aged; p38 Mitogen-Activated Protein Kinases; Phospholipases A2; Retina; Retinal Vein Occlusion; Retinal Vessels; Superoxides; Thrombin; Thromboxane B2; Treatment Outcome

We determined the levels of the stable urinary metabolites of thromboxane A2 and prostacyclin, 11-dehydro-thromboxane B2 (11-dehydro-TXB2) and 2,3-dinor-6-keto-prostaglandin F1alpha (2,3-dinor-6-keto-PGF1alpha) in patients with retinal vascular occlusion (RVO) to elucidate the change of the thromboxane A2/prostacyclin (TX/PGI) ratio with this disease and the effect of low-dose-aspirin therapy. 11-Dehydro-TXB2 and 2,3-dinor-6-keto-PGF1alpha were converted to 1-methyl ester-propylamide-9,12,15-tris-dimethylisopropylsilyl ether derivative and 1-methyl ester-6-methoxime-9,12,15-tris-dimethylisopropylsilyl ether derivative, respectively, and applied to a gas chromatography/selected ion monitoring. The average level of 11-dehydro-TXB2 in 30 patients with RVO was 1038 +/- 958 pg/mg creatinine. It was significantly higher than that of 27 healthy volunteers, which was 616 +/- 294 pg/mg creatinine (p < 0.05 with unpaired t-test). However, 2,3-dinor-6-keto-PGF1alpha levels were not significantly different between these two groups. The average ratio of TX/PGI in the RVO patients was 32 +/- 26 and it was significantly higher than that of healthy volunteers, 17 +/- 10 (p < 0.01). Patients with central retinal artery occlusion or branch retinal artery occlusion showed greatly high 11-dehydro-TXB2 levels and TX/PGI ratios, although the number of patients was limited in the current study. After the administration of low-dose aspirin (40 mg/day) for about 1 month, the TX/PGI ratio decreased to around the normal level. Following the levels for up to 10 months, they also remained at the normal level. These observations suggested that the 11-dehydro-TXB2 levels and the TX/PGI ratio reflect the pathological conditions of RVO and are useful markers of the treatment.

Topics: 6-Ketoprostaglandin F1 alpha; Aged; Aspirin; Dose-Response Relationship, Drug; Epoprostenol; Female; Gas Chromatography-Mass Spectrometry; Humans; Male; Middle Aged; Pilot Projects; Prostaglandins F; Retinal Artery Occlusion; Retinal Vein Occlusion; Thromboxane A2; Thromboxane B2; Thromboxanes

We describe variations of 11-dehydrothromboxane B2(11-dehydro-TXB2) levels in human urine samples. Retinal vein occlusion (RVO) is a thrombotic disease in which the retinal vein is blocked by blood aggregations. We considered the possibility that 11-dehydro-TXB2 plays an important role in the formation of RVO. Thus, we determined the 11-dehydro-TXB2 levels in patients with RVO using gas chromatography/selected ion monitoring (GC/SIM) and compared them with those of healthy volunteers. The thromboxane levels in patients with RVO, who did not also have diabetes, were significantly higher than those in healthy volunteers. One cause of RVO may be the variation of thromboxane production. Furthermore, this GC/SIM method can be applied to the prevention and treatment of not only RVO, but also of general thrombosis.

Topics: Adult; Aged; Chromatography, Gas; Female; Humans; Male; Middle Aged; Retinal Vein Occlusion; Thrombosis; Thromboxane B2

Plasma TxB2 and 6-keto-PGF1 alpha were measured in 16 patients with central retinal vein occlusion (CRVO) and 18 patients with branch retinal vein occlusion (BRVO) as well as 21 normal controls by radioimmunoassay. The results showed that the ratio of TxB2/6-keto-PGF1 alpha (T/P) was higher in CRVO or BRVO than in control. The prime reason of high T/P value was the increase of plasma TxB2 in CRVO, while the prime reason was the decrease of plasma 6-keto-PGF1 alpha in BRVO. The results indicate that the pathogenesis of CRVO is related to the high platelet aggregation and the changes in blood rheology or hemodynamics, while the pathogenesis of BRVO mainly depends on the pathologic changes of endothelium in systemic and retinal blood vessels.

Topics: 6-Ketoprostaglandin F1 alpha; Adult; Aged; Female; Humans; Male; Middle Aged; Retinal Vein Occlusion; Thromboxane B2