Therapy of pancreatic cancer via an EphA2 receptor-targeted delivery of gemcitabine.

First line treatment for pancreatic cancer consists of surgical resection, if possible, and a subsequent course of chemotherapy using the nucleoside analogue gemcitabine. In some patients, an active transport mechanism allows gemcitabine to enter efficiently into the tumor cells, resulting in a significant clinical benefit. However, in most patients, low expression of gemcitabine transporters limits the efficacy of the drug to marginal levels, and patients need frequent administration of the drug at high doses, significantly increasing systemic drug toxicity. In this article we focus on a novel targeted delivery approach for gemcitabine consisting of conjugating the drug with an EphA2 targeting agent. We show that the EphA2 receptor is highly expressed in pancreatic cancers, and accordingly, the drug-conjugate is more effective than gemcitabine alone in targeting pancreatic tumors. Our preliminary observations suggest that this approach may provide a general benefit to pancreatic cancer patients and offers a comprehensive strategy for enhancing delivery of diverse therapeutic agents to a wide range of cancers overexpressing EphA2, thereby potentially reducing toxicity while enhancing therapeutic efficacy

Total nuclear disarmament: ethical and moral issues

Moving focus from the geostrategic and political realms to ethical and moral ones can lead to a better understanding of the paradox of “guaranteeing peace” by means of implementing an . infrastructure for the extinction of mankind (i.e. the nuclear weapons industry). A possible way forward is derived from this major paradigm shift. The analysis is contextualized within the broader scope of questioning the implicit legitimization of unrestrained tampering with nature, from matter to life

Structure-guided design and optimization of small molecules targeting the protein-protein interaction between the von hippel-lindau (VHL) E3 ubiquitin ligase and the hypoxia inducible factor (HIF) alpha subunit with in vitro nanomolar affinities

E3 ubiquitin ligases are attractive targets in the ubiquitin-proteasome system, however, the development of small-molecule ligands has been rewarded with limited success. The von Hippel-Lindau protein (pVHL) is the substrate recognition subunit of the VHL E3 ligase that targets HIF-1α for degradation. We recently reported inhibitors of the pVHL:HIF-1α interaction, however they exhibited moderate potency. Herein, we report the design and optimization, guided by X-ray crystal structures, of a ligand series with nanomolar binding affinities

The structure of the PapD-PapGII pilin complex reveals an open and flexible P5 pocket

P pili are hairlike polymeric structures that mediate binding of uropathogenic Escherichia coli to the surface of the kidney via the PapG adhesin at their tips. PapG is composed of two domains: a lectin domain at the tip of the pilus followed by a pilin domain that comprises the initial polymerizing subunit of the 1,000-plus-subunit heteropolymeric pilus fiber. Prior to assembly, periplasmic pilin domains bind to a chaperone, PapD. PapD mediates donor strand complementation, in which a beta strand of PapD temporarily completes the pilin domain's fold, preventing premature, nonproductive interactions with other pilin subunits and facilitating subunit folding. Chaperone-subunit complexes are delivered to the outer membrane usher where donor strand exchange (DSE) replaces PapD's donated beta strand with an amino-terminal extension on the next incoming pilin subunit. This occurs via a zip-in-zip-out mechanism that initiates at a relatively accessible hydrophobic space termed the P5 pocket on the terminally incorporated pilus subunit. Here, we solve the structure of PapD in complex with the pilin domain of isoform II of PapG (PapGIIp). Our data revealed that PapGIIp adopts an immunoglobulin fold with a missing seventh strand, complemented in parallel by the G1 PapD strand, typical of pilin subunits. Comparisons with other chaperone-pilin complexes indicated that the interactive surfaces are highly conserved. Interestingly, the PapGIIp P5 pocket was in an open conformation, which, as molecular dynamics simulations revealed, switches between an open and a closed conformation due to the flexibility of the surrounding loops. Our study reveals the structural details of the DSE mechanism

'We are part of a family' : benefits and limitations of community ART groups (CAGs) in Thyolo, Malawi : a qualitative study

Introduction: In 2012 Community ART Groups (CAGs), a community-based model of antiretroviral therapy (ART) delivery were piloted in Thyolo District, Malawi as a way to overcome patient barriers to accessing treatment, and to decrease healthcare workers' workload. CAGs are self-formed groups of patients on ART taking turns to collect ART refills for all group members from the health facility. We conducted a qualitative study to assess the benefits and challenges of CAGs from patients' and healthcare workers' (HCWs) perspectives. Methods: Data were collected by means of 15 focus group discussions, 15 individual in-depth interviews, and participant observation in 2 health centres. The 94 study participants included CAG members, ART patients eligible for CAGs who remained in conventional care, former CAG members who returned to conventional care and HCWs responsible for providing HIV care. Patient participants were purposively selected from ART registers, taking into account age and gender. Narratives were audio-recorded, transcribed, and translated from Chichewa to English. Data were analyzed through a thematic analysis. Results: Patients and HCWs spoke favourably about the practical benefits of CAGs. Patient benefits included a reduced frequency of clinic visits, resulting in reduced transportation costs and time savings. HCW benefits included a reduced workload. Additionally peer support was perceived as an added value of the groups allowing not only sharing of the logistical constraints of drugs refills, but also enhanced emotional support. Identified barriers to joining a CAG included a lack of information on CAGs, unwillingness to disclose one's HIV status, change of residence and conflicts among CAG members. Participants reported that HIV-related stigma persists and CAGs were seen as an effective strategy to reduce exposure to discriminatory labelling by community members. Conclusions: In this setting, patients and HCWs perceived CAGs to be an acceptable model of ART delivery. Despite addressing important practical barriers to accessing ART, and providing peer support, CAGs were not well known by patients and had a limited impact on reducing HIV-related stigma. The CAG model of ART delivery should be considered in similar settings. Further measures need to be devised and implemented to address HIV-related stigma

Asymmetric protonation of EmrE

The small multidrug resistance transporter EmrE is a homodimer that uses energy provided by the proton motive force to drive the efflux of drug substrates. The pKa values of its “active-site” residues—glutamate 14 (Glu14) from each subunit—must be poised around physiological pH values to efficiently couple proton import to drug export in vivo. To assess the protonation of EmrE, pH titrations were conducted with (1)H-(15)N TROSY-HSQC nuclear magnetic resonance (NMR) spectra. Analysis of these spectra indicates that the Glu14 residues have asymmetric pKa values of 7.0 ± 0.1 and 8.2 ± 0.3 at 45°C and 6.8 ± 0.1 and 8.5 ± 0.2 at 25°C. These pKa values are substantially increased compared with typical pKa values for solvent-exposed glutamates but are within the range of published Glu14 pKa values inferred from the pH dependence of substrate binding and transport assays. The active-site mutant, E14D-EmrE, has pKa values below the physiological pH range, consistent with its impaired transport activity. The NMR spectra demonstrate that the protonation states of the active-site Glu14 residues determine both the global structure and the rate of conformational exchange between inward- and outward-facing EmrE. Thus, the pKa values of the asymmetric active-site Glu14 residues are key for proper coupling of proton import to multidrug efflux. However, the results raise new questions regarding the coupling mechanism because they show that EmrE exists in a mixture of protonation states near neutral pH and can interconvert between inward- and outward-facing forms in multiple different protonation states