Hyaluronan synthase mediates dye translocation across liposomal membranes

<p>Abstract</p> <p>Background</p> <p>Hyaluronan (HA) is made at the plasma membrane and secreted into the extracellular medium or matrix by phospolipid-dependent hyaluronan synthase (HAS), which is active as a monomer. Since the mechanism by which HA is translocated across membranes is still unresolved, we assessed the presence of an intraprotein pore within HAS by adding purified <it>Streptococcus equisimilis </it>HAS (SeHAS) to liposomes preloaded with the fluorophore Cascade Blue (CB).</p> <p>Results</p> <p>CB translocation (efflux) was not observed with mock-purified material from empty vector control <it>E. coli </it>membranes, but was induced by SeHAS, purified from membranes, in a time- and dose-dependent manner. CB efflux was eliminated or greatly reduced when purified SeHAS was first treated under conditions that inhibit enzyme activity: heating, oxidization or cysteine modification with N-ethylmaleimide. Reduced CB efflux also occurred with SeHAS K48E or K48F mutants, in which alteration of K48 within membrane domain 2 causes decreased activity and HA product size. The above results used liposomes containing bovine cardiolipin (BCL). An earlier study testing many synthetic lipids found that the best activating lipid for SeHAS is tetraoleoyl cardiolipin (TO-CL) and that, in contrast, tetramyristoyl cardiolipin (TM-CL) is an inactivating lipid (Weigel et al, J. <it>Biol. Chem</it>. <b>281</b>, 36542, 2006). Consistent with the effects of these CL species on SeHAS activity, CB efflux was more than 2-fold greater in liposomes made with TO-CL compared to TM-CL.</p> <p>Conclusions</p> <p>The results indicate the presence of an intraprotein pore in HAS and support a model in which HA is translocated to the exterior by HAS itself.</p

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Impact of age, comorbidity, and polypharmacy on the efficacy and safety of edoxaban for the treatment of venous thromboembolism: An analysis of the randomized, double-blind Hokusai-VTE trial

Background Many patients with venous thromboembolism (VTE) are elderly, have multiple comorbidities and take several concomitant medications. Physicians may prefer warfarin over direct oral anticoagulants (DOACs) in such patients because comparative data are lacking. This analysis was designed to determine the effects of advanced age, comorbidities, and polypharmacy on the efficacy and safety of edoxaban and warfarin in patients with VTE. Methods Using data from the Hokusai-VTE study, we report rates of recurrent VTE and of clinically relevant bleeding by age category (&lt; 65, 65\ue2\u80\u9375, and \ue2\u89\ua5 75; &lt; 80 versus \ue2\u89\ua5 80 years), and by number of comorbidities (0, 1\ue2\u80\u932, &gt; 2) and concomitant medications (&lt; 3, 3\ue2\u80\u935, &gt; 5). Hazard ratios (HR) and corresponding 95% confidence intervals (CI) for edoxaban versus warfarin were determined and Kaplan-Meier methodology was used to construct time-to-event curves. At 3 months, pre- and postdose levels of edoxaban were measured using mass spectrometry. For warfarin-treated patients, the time in therapeutic range was calculated. The study was approved by institutional review boards; informed consent was obtained. Results Recurrent VTE increased with advanced age, multiple comorbidities, and polypharmacy in warfarin-treated patients but not with edoxaban. Edoxaban was more effective than warfarin in patients \ue2\u89\ua5 75 years of age and in those with multiple comorbidities. In the 517 patients over 80 years of age, recurrent VTE occurred in 2.8% given edoxaban and in 5.7% given warfarin (HR 0.51, 95% CI 0.21\ue2\u80\u931.24). Bleeding increased with age, comorbidity, and polypharmacy regardless of treatment, but the relative safety of edoxaban versus well-managed warfarin was maintained. Age, comorbidity, and polypharmacy did not impact edoxaban concentrations. Conclusions These data suggest that a once-daily fixed dose of edoxaban is more effective and at least as safe as warfarin in high-risk VTE patients identified by older age, more comorbidities, and polypharmacy. Clinical trial registration: NCT0098615

Impact of age, comorbidity, and polypharmacy on the efficacy and safety of edoxaban for the treatment of venous thromboembolism: An analysis of the randomized, double-blind Hokusai-VTE trial

Many patients with venous thromboembolism (VTE) are elderly, have multiple comorbidities and take several concomitant medications. Physicians may prefer warfarin over direct oral anticoagulants (DOACs) in such patients because comparative data are lacking. This analysis was designed to determine the effects of advanced age, comorbidities, and polypharmacy on the efficacy and safety of edoxaban and warfarin in patients with VTE.status: publishe