The solution structure of sarafotoxin-c: implications for ligand recognition by endothelin

The solution structure of sarafotoxin-c has been determined using NMR spectroscopy. A total of 112 interproton distance constraints derived from two-dimensional MMR spectra were used to calculate a family of structures using a combination of distance geometry and dynamical simulated annealing calculations. The structures reveal a well defined cu helix extending from Glu(9) to Cys(15) and an N-terminal region (Cys(1)-Asp(8)) that is tightly constrained by disulfide bands to Cys residues in the central helix. In contrast, the C-terminal region (His(16)-Trp(21)) does not adopt a defined conformation in the final family of structures. This is consistent with the paucity of NMR-derived structural constraints obtained for this region and leads to the suggestion that the C-terminal region oscillates rapidly between a number of substantially different conformers. It is proposed that differences between the central helix of the endothelin and sarafotoxin isopeptides might be important in binding of these ligands by the G protein-coupled endothelin receptors

Centipede venoms as a source of drug leads

peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=iedc20© 2016 Taylor and Francis. The attached document is the authors' final submitted version of the journal article. You are advised to consult the publisher's version if you wish to cite from it

From foe to friend: using animal toxins to investigate ion channel function

Ion channels are vital contributors to cellular communication in a wide range of organisms, a distinct feature that renders this ubiquitous family of membrane-spanning proteins a prime target for toxins found in animal venom. For many years, the unique properties of these naturally-occurring molecules have enabled researchers to probe the structural and functional features of ion channels and to define their physiological roles in normal and diseased tissues. To illustrate their considerable impact on the ion channel field, this review will highlight fundamental insights into toxin-channel interactions as well as recently developed toxin screening methods and practical applications of engineered toxins

Proton-Recoil Spectrometer for Fast Neutron Spectra

This manuscript was published as Transactions of the American Nuclear Society, 8, 73 (June 1965)http://deepblue.lib.umich.edu/bitstream/2027.42/86077/1/MMPP Harris-Knoll-King 1965.PDF15

The mediating role of innovation in the relationship between market orientation and university performance in Pakistan

Universities globally are going through a paradigm shift with a need to become more innovatively market-oriented to handle the issue of growing competition for funding, as well as attracting/retaining the international/local competent students and academicians. However, there appears to be a dearth of research on how such state of affairs could be addressed, particularly in the emerging economies like Pakistan. In the light of resource-based theory (RBT), as well as organizational-learning theory (OLT), literature suggests that market-orientation (MO) and innovation are to be the desirable unique resources, as well as the guiding philosophies, to enable universities for a more competitive performance. Hence, this study investigated how resources like marketorientation (MO), and innovation, can influence university performance (UP). The study also tested empirically the potential mediating effect of innovation on the MOUP relationship. In addition, how the dimensions of MO influenced the innovation and university performance (UP) were also tested empirically in the universities of Pakistan. Results of the PLS path modelling (with 369 respondents from the target public-sector universities) firstly confirmed significant effect of the “universal construct of MO” and two of its dimensions “the advising and mentoring, as well as the intelligencegeneration and response” on UP. However, one dimension of MO, which is the administration-leadership, was not significantly supported to directly influence the UP. Secondly, the study confirmed that there were significant direct effects of the “universal construct of MO”, as well as all of its dimensions, on innovation. Thirdly, the study also found that there was a significant effect of innovation on UP. Furthermore, the bootstrapping results found significant mediation of innovation between the MO-UP relationship. Hence, the results show that UP can be directly enhanced through MO and innovation. Even the use of innovation as a mediator can further strengthen the MO-UP relationship. Based on the findings, the study offers theoretical and practical implications, followed by its limitations and directions, for future research

A comprehensive portrait of the venom of the giant red bull ant, Myrmecia gulosa, reveals a hyperdiverse hymenopteran toxin gene family

Ants (Hymenoptera: Formicidae) are diverse and ubiquitous, and their ability to sting is familiar to many of us. However, their venoms remain largely unstudied. We provide the first comprehensive characterization of a polypeptidic ant venom, that of the giant red bull ant, Myrmecia gulosa. We reveal a suite of novel peptides with a range of posttranslational modifications, including disulfide bond formation, dimerization, and glycosylation. One venom peptide has sequence features consistent with an epidermal growth factor fold, while the remaining peptides have features suggestive of a capacity to form amphipathic helices. We show that these peptides are derived from what appears to be a single, pharmacologically diverse, gene superfamily (aculeatoxins) that includes most venom peptides previously reported from the aculeate Hymenoptera. Two aculeatoxins purified from the venom were found to be capable of activating mammalian sensory neurons, consistent with the capacity to produce pain but via distinct mechanisms of action. Further investigation of the major venom peptide MIITX1-Mg1a revealed that it can also incapacitate arthropods, indicative of dual utility in both defense and predation. MIITX1-Mg1a accomplishes these functions by generating a leak in membrane ion conductance, which alters membrane potential and triggers neuronal depolarization. Our results provide the first insights into the evolution of the major toxin gene superfamily of the aculeate Hymenoptera and provide a new paradigm in the functional evolution of toxins from animal venoms.ARC, NHMR

Periplasmic Expression of 4/7 α-Conotoxin TxIA Analogs in E. coli Favors Ribbon Isomer Formation – Suggestion of a Binding Mode at the α7 nAChR

Peptides derived from animal venoms provide important research tools for biochemical and pharmacological characterization of receptors, ion channels, and transporters. Some venom peptides have been developed into drugs (such as the synthetic omega-conotoxin MVIIA, ziconotide) and several are currently undergoing clinical trials for various clinical indications. Challenges in the development of peptides include their usually limited supply from natural sources, cost-intensive chemical synthesis, and potentially complicated stereoselective disulfide-bond formation in the case of disulfide-rich peptides. In particular, if extended structure-function analysis is performed or incorporation of stable isotopes for NMR studies is required, the comparatively low yields and high costs of synthesized peptides might constitute a limiting factor. Here we investigated the expression of the 4/7 alpha-conotoxin TxIA, a potent blocker at alpha 3 beta 2 and alpha 7 nicotinic acetylcholine receptors (nAChRs), and three analogs in the form of maltose binding protein fusion proteins in Escherichia coli. Upon purification via nickel affinity chromatography and release of the toxins by protease cleavage, HPLC analysis revealed one major peak with the correct mass for all peptides. The final yield was 1-2 mg of recombinant peptide per liter of bacterial culture. Two-electrode voltage clamp analysis on oocyte-expressed nAChR subtypes demonstrated the functionality of these peptides but also revealed a 30 to 100-fold potency decrease of expressed TxIA compared to chemically synthesized TxIA. NMR spectroscopy analysis of TxIA and two of its analogs confirmed that the decreased activity was due to an alternative disulfide linkage rather than the missing C-terminal amidation, a post-translational modification that is common in alpha-conotoxins. All peptides preferentially formed in the ribbon conformation rather than the native globular conformation. Interestingly, in the case of the alpha 7 nAChR, but not the alpha 3 beta 2 subtype, the loss of potency could be rescued by an R5D substitution. In conclusion, we demonstrate efficient expression of functional but alternatively folded ribbon TxIA variants in E. coli and provide the first structure-function analysis for a ribbon 4/7-alpha-conotoxin at alpha 7 and alpha 3 beta 2 nAChRs. Computational analysis based on these data provide evidence for a ribbon alpha-conotoxin binding mode that might be exploited to design ligands with optimized selectivity

PcTx1 affords neuroprotection in a conscious model of stroke in hypertensive rats via selective inhibition of ASIC1a

Acid-sensing ion channel la (ASIC1a) is the primary acid sensor in mammalian brain and plays a major role in neuronal injury following cerebral ischemia. Evidence that inhibition of ASIC1a might be neuroprotective following stroke was previously obtained using "PcTx1 venom" from the tarantula Psalmopeous cambridgei. We show here that the ASIC1a-selective blocker PcTx1 is present at only 0.4% abundance in this venom, leading to uncertainty as to whether the observed neuroprotective effects were due to PcTx1 blockade of ASIC1a or inhibition of other ion channels and receptors by the hundreds of peptides and small molecules present in the venom. We therefore examined whether pure PcTx1 is neuroprotective in a conscious model of stroke via direct inhibition of ASIC1a. A focal reperfusion model of stroke was induced in conscious spontaneously hypertensive rats (SHR) by administering endothelin-1 to the middle cerebral artery via a surgically implanted cannula. Two hours later, SHR were treated with a single intracerebroventricular (i.c.v.) dose of PcTx1 (1 ng/kg), an ASIC1a-inactive mutant of PcTx1 (1 ng/kg), or saline, and ledged beam and neurological tests were used to assess the severity of symptomatic changes. PcTx1 markedly reduced cortical and striatal infarct volumes measured 72 h post-stroke, which correlated with improvements in neurological score, motor function and preservation of neuronal architecture. In contrast, the inactive PcTx1 analogue had no effect on stroke outcome. This is the first demonstration that selective pharmacological inhibition of ASIC1a is neuroprotective in conscious SHRs, thus validating inhibition of ASIC1a as a potential treatment for stroke. (C) 2015 Elsevier Ltd. All rights reserved

Transition to Virtual Asthma Care During the COVID-19 Pandemic: An Observational Study

BACKGROUND: The COVID-19 pandemic increased reliance on virtual care for patients with persistent asthma. OBJECTIVE: This retrospective cohort study assessed changes from in-person to virtual care during the pandemic. In patients with persistent asthma, compared with the same period before the pandemic. METHODS: Kaiser Permanente Colorado members aged 18 to 99 years with persistent asthma were evaluated during two periods (March to October 2019 and March to October 2020). Comparison of asthma exacerbations (hospitalizations, emergency department visits, and courses of oral prednisone) and asthma medication metrics were evaluated between the two periods and by type of care received during the pandemic (no care, virtual care only, in-person care only, or a mix of virtual and in-person care). Population characteristics by type of care received during the pandemic were also evaluated. RESULTS: Among 7,805 adults with persistent asthma, those who used more virtual care or sought no care during the pandemic were younger and had fewer comorbidities, mental health diagnoses, or financial barriers. Exacerbations decreased (0.264 to 0.214; P <.001) as did courses of prednisone (0.213 to 0.169). Asthma medication adherence (0.53 to 0.54; P <.001) and the asthma medication ratio, a quality-of-care metric (0.755 to 0.762; P [ .019), increased slightly. Patients receiving a mix of in-person and virtual care had the highest rate of exacerbations (0.83) and a lower asthma medication ratio (0.74) despite having the highest adherence (.57). CONCLUSIONS: Despite an increase in virtual care, asthma exacerbations decreased except among individuals who received both in-person and virtual care, likely because they had more severe disease.Ye