Increased serum levels of leptin in retinal vein occlusion

Possible retinotoxicity of long-term vardenafil treatment

Phosphodiesterase (PDE) inhibitors - such as vardenafil - are used primarily for treating erectile dysfunction via increasing cyclic guanosine monophosphate (cGMP) levels. Recent studies have also demonstrated their significant cardioprotective effects in several diseases, including diabetes, upon long-term, continuous application. However, PDE inhibitors are not specific for PDE5 and also inhibit the retinal isoform. A sustained rise in cGMP in photoreceptors is known to be toxic; therefore, we hypothesized that long-term vardenafil treatment might result in retinotoxicity. The hypothesis was tested in a clinically relevant animal model of type 2 diabetes mellitus. Histological experiments were performed on lean and diabetic Zucker Diabetic Fatty rats. Half of the animals were treated with vardenafil for six months, and the retinal effects were evaluated. Vardenafil treatment alleviated rod outer segment degeneration but decreased rod numbers in some positions and induced changes in the interphotoreceptor matrix, even in control animals. Vardenafil treatment decreased total retinal thickness in the control and diabetic groups and reduced the number of nuclei in the outer nuclear layer. Müller cell activation was detectable even in the vardenafil-treated control animals, and vardenafil did not improve gliosis in the diabetic group. Vardenafil-treated animals showed complex retinal alterations with improvements in some parameters while deterioration in others. Our results point towards the retinotoxicity of vardenafil, even without diabetes, which raises doubts about the retinal safety of long-term continuous vardenafil administration. This effect needs to be considered when approving PDE inhibitors for alternative indications.

High preoperative serum leptin level is an independent risk factor for deep vein thrombosis after total knee arthroplasty in osteoarthritis patients: A prospective and cross-sectional study

It suggests that a high leptin level may increase the risk of venous thromboembolism (VTE) in animal studies. However, clinical studies in this field are still largely unexplored. Our objective was to evaluate the relationship between the preoperative serum leptin levels and postoperative VTE incidence in osteoarthritis (OA) patients who underwent total knee arthroplasty (TKA) at our institute.We conducted a prospective and cross-sectional study in these OA patients from March 2014 to March 2016. Preoperative leptin levels were analyzed by Luminex assays. VTE was assessed preoperatively and on postoperative day 5 and 7. The potential risk factors for VTE were also documented.We enrolled 203 OA patients. No PE was detected and DVT was diagnosed in 34 patients postoperatively. There were significant differences between the median leptin levels in DVT group and non-DVT group [25.13 ng/mL (interquartile range, 14.51-44.31) vs 18.71 ng/mL (8.26-28.99), P = .007]. The relative risk of DVT significantly increased with natural logarithm (ln) leptin (per SD increase) (OR 2.37, 95% confidence interval (95% CI), 1.29-4.33, P = .005). Multivariate analyses adjusted for potential confounders showed ln leptin (per SD increase) was significantly associated with the relative risk of DVT (OR 2.17, 95% CI, 1.01-4.64, P = .046). When patients were subdivided into tertiles according to their leptin values, the OR for DVT increased with increasing tertiles of serum leptin (OR 1.03, 95% CI, 1.01-1.06, P for trend = .023).In the present study, our results indicate that a high preoperative leptin level may be an independent risk factor for postoperative DVT.