Plasma levels of endothelin-1 in diabetic retinopathy in pregnancy

Diabetic retinopathy in pregnancy - A review

Diabetes and gestational diabetes (GD) are areas of concern worldwide. GD can eventually lead to serious development of diabetic retinopathy (DR) during pregnancy or worsening of an already existing DR. GD confers future risk of diabetes, both in the mother and fetus, further complicating their lives. DR in pregnant women has been intriguing in terms of understanding the prevalence, assessing risk factors causing pathogenesis, and problems associated with treating them. Pregnancy itself is a risk factor for progression of DR. Physiological changes such as metabolic, vascular, immunologic, and hormonal changes that occur during pregnancy can cause development as well as worsening of DR. This can eventually lead to permanent visual loss if not addressed on time. Timing of laser, choice of treatment for diabetic macular edema with laser, intravitreal anti-vascular endothelial growth factor agents (VEGF), and intravitreal steroids pose a serious challenge in managing these patients without causing damage to the mother and fetus. This review article showcases the prevalence, risk factors, and pathogenesis, outlines the management of DR in pregnancy, and recommends guidelines based on the available evidence. PubMed and MEDLINE searches were performed pertaining to the prevalence of GD in India, DR in pregnancy, risk factors for progression of DR, role of vasoactive mediators in DR, role of angiopoietic factors in DR, hormonal influence of DR, role of growth factors in DR, use of fluorescein and indocyanine green angiography, retinal lasers, anti-VEGF agents, intravitreal steroids, anesthesia, and retinal surgery, all pertaining to pregnancy and guidelines and recommendations for managing DR in pregnancy.

Circulating asymmetric dimethylarginine, endothelin-1 and cell adhesion molecules in women with gestational diabetes

We measured plasma concentrations of asymmetric dimethylarginine (ADMA), endothelin-1 (ET-1), soluble vascular cell adhesion molecule-1 (sVCAM-1) and E-selectin in 56 patients with gestational diabetes (GDM), 68 pregnant women with normal glucose tolerance (NGT) and 36 healthy non-pregnant women. ADMA concentrations were markedly lower in NGT [0.48 (0.42-0.55) micromol/l] than in GDM subjects [0.50 (0.43-0.67) micromol/l] and healthy controls [0.57 (0.46-0.72) micromol/l, P = 0.005]. ET-1 levels were comparable between GDM [0.76 (0.58-0.90) pg/ml] and NGT women [0.75 (0.63-0.92) pg/ml] and significantly higher than in the non-pregnant subjects [0.62 (0.52-0.72) pg/ml, P = 0.007 and P = 0.005, respectively]. There were no differences in sVCAM-1 and E-selectin levels between the groups studied. ADMA levels were significantly associated with fasting glucose (beta = 0.23, P = 0.02) and gestational age (beta = 0.24, P = 0.01). Our results suggest that physiological adaptation to pregnancy is associated with a fall in circulating ADMA and an elevation of ET-1 concentrations, irrespective of the disturbances of glucose tolerance.

Endothelium-derived nitric oxide metabolites and soluble intercellular adhesion molecule-1 in diabetic and normal pregnancies

OBJECTIVE

Endothelial dysfunction has been demonstrated in adult subjects with diabetes. We studied if maternal diabetes is associated with altered endothelial function in the fetus, as this might shed light on mechanisms by which adult diseases are programmed in utero.

STUDY DESIGN

Total nitrate/nitrite (NOx) concentration was measured spectrophotometrically with the Griess reagent method. Soluble intercellular adhesion molecule-1 (sICAM-1) concentration was measured by enzyme-linked immunoassay.

RESULTS

Venous cord serum NOx concentration at birth was highest in pregnancies complicated by type 1 diabetes (29.5+/-1.8 micromol/l, n=63) (P<0.0001 versus controls) and lowest in normal pregnancies (19.0+/-1.0 micromol/l, n=56). The concentration was intermediate in pregnancies complicated by gestational diabetes (23.9+/-2.7 micromol/l, n=24), but not significantly higher than in normal pregnancies (P=0.172). Venous cord serum sICAM-1 concentration did not differ between the three groups (P=0.191). Maternal serum NOx concentration in the third trimester was higher in pregnancies complicated by type 1 diabetes (22.9+/-3.4 micromol/l, n=22) than in normal pregnancies (15.4+/-1.4 micromol/l, n=21) (P=0.049).

CONCLUSIONS

: Increased cord serum NOx but unaltered sICAM-1 concentration in diabetic pregnancies indicates that maternal diabetes does not cause a general alteration in fetal endothelial function. The increase in cord serum and maternal serum NOx concentration in diabetic pregnancies may be due to abnormalities in insulin-induced nitric oxide release or to a diminished reactivity of the vasculature to the effects of nitric oxide.

Ocular perfusion abnormalities in diabetes

PURPOSE

To review the role of ocular perfusion in the pathophysiology of diabetic retinopathy, one of the leading causes of irreversible blindness in the industrialized world.

METHODS

We carried out a Medline search of the literature published in English or with English abstracts from 1966 to 2000 using various combinations of relevant key words.

RESULTS

Hyperglycaemia leads to a wide variety of vascular abnormalities at the microvascular and macrovascular levels, including abnormal autoregulation.

CONCLUSION

Three major aspects of ocular perfusion in diabetic retinopathy require additional investigation. Firstly, the precise mechanisms that link elevated glucose to dysfunction of retinal vascular cells need to be identified. Secondly, those factors that lead to both capillary dropout and to angiogenesis, twin processes that are linked to tissue hypoxia and lead to excess perfusion, increased risk of extravascular leakage and frank haemorrhage, must be carefully delineated. Finally, once specific knowledge of disease fundamentals has been amassed, tests of therapies to reverse or prevent these pathological processes can move forward.