Root hairs secrete ATP as they grow, and extracellular ATP and ADP can trigger signaling pathways that regulate plant cell growth. In several plant tissues the level of extracellular nucleotides is limited in part by ectoapyrases (ecto-NTPDases), and the growth of these tissues is strongly influenced by their level of ectoapyrase expression. Both chemical inhibition of ectoapyrase activity and suppression of the expression of two ectoapyrase enzymes by RNAi in Arabidopsis resulted in inhibition of root hair growth. As assayed by a dose-response curve, different concentrations of the poorly hydrolysable nucleotides, ATPγS and ADPβS, could either stimulate (at 7.5-25 μM) or inhibit (at ≥ 150 μM) the growth rate of root hairs in less than an hour. Equal amounts of AMPS, used as a control, had no effect on root hair growth. Root hairs of nia1nia2 mutants, which are suppressed in nitric oxide (NO) production, and of atrbohD/F mutants, which are suppressed in the production of H(2)O(2), did not show growth responses to applied nucleotides, indicating that the growth changes induced by these nucleotides in wild-type plants were likely transduced via NO and H(2)O(2) signals. Consistent with this interpretation, treatment of root hairs with different concentrations of ATPγS induced different accumulations of NO and H(2)O(2) in root hair tips. Two mammalian purinoceptor antagonists also blocked the growth responses induced by extracellular nucleotides, suggesting that they were initiated by a receptor-based mechanism.

Introduction: Diabetes mellitus is a systemic disease with complications that include sight-threatening diabetic retinopathy. It is essential to understand the risk factors of diabetic retinopathy before effective prevention can be implemented. The aim of this review was to examine the association between diabetic retinopathy and systemic risk factors.Methods: A PubMed literature search was performed up to May 2016 to identify articles reporting associations between diabetic retinopathy and systemic risk factors; only publications written in English were included. Relevant articles were selected and analysed. Results:Patients with diabetic retinopathy were more likely to have poor glycaemic control as reflected by a higher glycated haemoglobin, longer duration of diabetes, and use of insulin therapy for treatment. For other systemic risk factors, hypertension was positively associated with prevalence and progression of diabetic retinopathy. No clear association between obesity, hyperlipidaemia, gender, or smoking with diabetic retinopathy has been established as Associations between diabetic retinopathy and systemic risk factors IntroductionDiabetic retinopathy is the leading cause of blindness in adults living in developed countries. 1 Almost all patients with type 1 diabetes mellitus (DM) and more than 60% of patients with type 2 DM will develop some degree of retinopathy after a 20-year history of diabetes.2 It has also been well established that DM increases the risk of cardiovascular disease. 3Cheng et al 4 found that the prevalence of diabetic retinopathy associated with one, two, three, or four cardiometabolic risk factors was 16.0%, 17.6%, 21.3%, or 25.1%, respectively (P=0.001). This implies a relationship between systemic health conditions and diabetic retinopathy. In order to help identify and to prevent progression of this ophthalmic complication of diabetes, a better understanding of its association with systemic risk factors is necessary. MethodsA PubMed literature search was conducted up to May 2016 using the following key words: "diabetic retinopathy", "prevalence", "epidemiology", "systemic associations", "risk factors", "diabetic Hong Kong Med J 2016;22:589-99

Topical olopatadine is a safe and effective treatment modality for allergic conjunctivitis, whereas alcaftadine appears to be superior to olopatadine in reducing ocular itch.