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Investigating how information propagates between layers in the olfactory system is an important step toward understanding the olfactory code. Each glomerular output projection neuron (PN) receives two sources of input: the olfactory receptor neurons (ORNs) of the same glomerulus and interneurons that innervate many glomeruli. We therefore asked how these inputs interact to produce PN output. We used receptor gene mutations to silence all of the ORNs innervating a specific glomerulus and recorded PN activity with two-photon calcium imaging and electrophysiology. We found evidence for balanced excitatory and inhibitory synaptic inputs but saw little or no response in the absence of direct ORN input. We next asked whether any transformation of activity occurs at successive layers of the antennal lobe. We found a strong link between PN firing and dendritic calcium elevation, the latter of which is tightly correlated with calcium activity in ORN axons, supporting the idea of glomerular propagation of olfactory information. Finally, we showed that odors are represented by a sparse population of PNs. Together, these results are consistent with the idea that direct receptor input provides the main excitatory drive to PNs, whereas interneurons modulate PN output. Balanced excitatory and inhibitory interneuron input may provide a mechanism to adjust PN sensitivity.antennal lobe ͉ gain modulation ͉ olfaction ͉ smell ͉ sparse code S ensory systems have the difficult task of encoding the identity and intensity of behaviorally relevant stimuli in the environment. The question of how these stimuli are encoded and propagated from the periphery to higher brain centers is central to systems neuroscience. The stereotypic organization of the Drosophila olfactory system and the identification of the odorant receptor genes make the fly an attractive model system in which to study the successive processing of sensory information.Drosophila olfactory receptor neurons (ORNs) in the antennae detect odors and relay neural activity to the antennal lobe in the brain. An adult fly expresses Ϸ50 odorant receptor genes (1-6). In the antennal lobe, axons of ORNs expressing the same receptor gene project with precision to spatially invariant glomeruli (4-7). Most second-order projection neurons (PNs) send dendrites to individual glomeruli in the antennal lobe and send axons to the mushroom body and the lateral horn of the protocerebrum (8-11).Imaging experiments in the insect antennal lobe (12-14) reveal a spatial map of glomerular activity. It has been hypothesized that each glomerulus is a functional unit and that the pattern of glomerular activity encodes the quality of odors (15). However, the Drosophila antennal lobe contains many GABAergic inhibitory interneurons (10,16,17), as well as a group of recently identified cholinergic excitatory interneurons (18). These two classes of interneurons apparently have opposing effects on PNs, and the extent to which they contribute to PN output is unknown. There are two general models for the function...

Summary Background To shorten the course of direct-acting antiviral agents for chronic hepatitis C virus (HCV) infection, we examined the antiviral efficacy and safety of 3 weeks of response-guided therapy with an NS3 protease inhibitor and dual NS5A inhibitor–NS5B nucleotide analogue. Methods In this open-label, phase 2a, single centre study, Chinese patients with chronic HCV genotype 1b infection without cirrhosis were randomly allocated by a computer program to one of three treatment groups (sofosbuvir, ledipasvir, and asunaprevir; sofosbuvir, daclatasvir, and simeprevir; or sofosbuvir, daclatasvir, and asunaprevir) until six patients in each group (1:1:1) achieved an ultrarapid virological response (plasma HCV RNA <500 IU/mL by day 2, measured by COBAS TaqMan HCV test, version 2.0). Patients with an ultrarapid virological response received 3 weeks of therapy. Patients who did not achieve an ultrarapid response were switched to sofosbuvir and ledipasvir for either 8 weeks or 12 weeks. The primary endpoint was the proportion of patients with a sustained virological response at 12 weeks (SVR12) after treatment completion, analysed in the intention-to-treat population. All patients who achieved an ultrarapid virological response were included in the safety analysis. This trial is registered with ClinicalTrials.gov, number NCT02470858. Findings Between April 5, 2015, and April 15, 2015, 26 eligible patients were recruited. 12 patients were assigned to sofosbuvir, ledipasvir, and asunaprevir; six to sofosbuvir, daclatasvir, and simeprevir; and eight to sofosbuvir, daclatasvir, and asunaprevir. Six patients in each group achieved an ultrarapid virological response (18 [69%]). All patients with an ultrarapid virological response who were given 3 weeks of triple therapy achieved SVR12. The most common adverse events were fatigue (one [17%] of six patients receiving sofosbuvir, ledipasvir, and asunaprevir; one [17%] of six patients receiving sofosbuvir, daclatasvir, and simeprevir; and two [33%] of six patients receiving sofosbuvir, daclatasvir, and asunaprevir) and headache (one [17%] patient in each group). No patients experienced any serious adverse events. Interpretation In this proof-of-concept study, all patients with chronic HCV without cirrhosis who achieved an ultrarapid virological response on triple direct-acting antiviral regimens by day 2 and received 3 weeks of treatment were cured, with excellent tolerability. By shortening the duration of therapy from the currently recommended 12 weeks to 3 weeks, we could drastically reduce the cost of therapy and the rate of adverse events. Further large-scale studies should be done to confirm our findings. Funding Center for AIDS Research, National Institutes of Health, US Department of Energy, National Center for Research Resources and the Office of Research Infrastructure Programs, Cheng Si-Yuan (China-International) Hepatitis Research Foundation, and Humanity and Health Medical Group.

Hepatitis C virus (HCV)4 constitutes a global health problem. Current therapies are unable to effectively eliminate viral infection in a significant number of patients. The RNA-dependent RNA polymerase (RdRp) of HCV NS5B is an attractive target for the development of orally bioavailable small molecule inhibitors (1, 2). The structure of the NS5B apoenzyme and the NS5B-RNA complex reveals the characteristic right hand architecture of polymerase enzymes, comprising three distinct domains (palm, thumb, and finger) encircling the enzyme active site located in the palm domain (3-6). The structural and biochemical characterization of HCV NS5B polymerase can provide a basis for drug design efforts, and the elucidation of the mechanism of inhibition can guide the optimization of inhibitor efficiency against wild-type and resistant mutants.Among the extensively investigated non-nucleosides documented to inhibit the RdRp activity of HCV NS5B, derivatives of various benzofuran and benzothiadiazine have been reported to bind to allosteric binding sites in the palm domain of NS5B (7,8). The palm domain, whose geometry is conserved in virtually all DNA and RNA polymerases, contains catalytic aspartic acids responsible for the nucleotidyl transfer reaction. The benzofuran compound HCV-796 has been shown to have significant antiviral effects in patients chronically infected with HCV (9, 10). In addition, two series of compounds based on the thiophene and benzimidazole scaffolds have been reported to inhibit NS5B by binding to two different binding pockets in the thumb domain of NS5B (11,12). The thumb domain is connected to the palm domain by a ␤-hairpin termed the primer grip motif. The C-terminal region of the thumb protrudes toward the active site (3). The thumb binding inhibitors have been proposed to inhibit the RdRp activity of NS5B, perhaps by interfering with template/primer interaction and conformational dynamics of the protein (13,14).Despite the elucidation of a number of NNIs that bind to the thumb and palm binding sites, the mechanism by which NNIs cause inhibition of RNA synthesis is unclear. Also, our understanding of the kinetics of NNI interaction with NS5B, the role of NNI binding and kinetics for inhibition, and the inhibitor efficacy on NS5B-resistant mutations remains incomplete. The four representative palm-and thumb-binding NNIs selected in this study have been reported to effectively inhibit replication of subgenomic replicons with low toxicity. Noncompetitive inhibition of NS5B polymerase activity with respect to NTPs has been reported (2, 15, 16). Based on co-crystallization studies with NS5B, it has been proposed that allosteric inhibitors may lock the NS5B protein in an inactive formation by binding tightly to the protein (16,17). It is important to understand how the binding affinity relates to inhibition potency and resistance to HCV inhibition. Because the intrinsic potency of slowly binding compounds can be underestimated in the short time □ S The on-line version of this article (available at htt...

Key words AbstractBackground: Breast reconstruction (BR) following mastectomy for breast cancer is safe and has high rates of patient satisfaction, yet only around 12% of Australian women undergo BR. This study presents BR rates and outcomes from a specialist practice that discusses reconstruction options with all women medically suitable for BR. Methods: Retrospective clinical study of all women that had undergone therapeutic mastectomy between 2009 and 2011. Patient, tumour and adjuvant therapy factors, and surgical complication rates, were compared between BR and no BR (NBR) patients. Results: Of the 331 women who had mastectomy for cancer, 136 (41%) had BR, with the vast majority (132, 97%) opting for immediate BR (IBR). Factors significantly associated with BR were young age, pure ductal carcinoma in-situ (DCIS), menopausal status and private health insurance. The main reasons for NBR were patient choice (88/195, 45%) and surgeon's perception of high-risk tumours (63/195, 32%). At mean follow-up of 15.6 months, five patients had developed local or distant recurrence (2 BR, 3 NBR). IBR did not cause significant delays in commencement of adjuvant therapy, and the BR group had a lower rate of surgical complications. Discussion: A BR rate of 41%, over three times the national average, was achieved when BR was discussed with all patients. This significant gain in BR rate was not accompanied by a commensurate increase in adverse outcomes, providing evidence that expanding the indications for BR to women who were previously not considered eligible is a valid option.