Development of a Hypersensitive Periodate‐Cleavable Amino Acid that is Methionine‐ and Disulfide‐Compatible and its Application in MHC Exchange Reagents for T Cell Characterisation

Incorporation of cleavable linkers into peptides and proteins is of particular value in the study of biological processes. Here we describe the synthesis of a cleavable linker that is hypersensitive to oxidative cleavage as the result of the periodate reactivity of a vicinal amino alcohol moiety. Two strategies directed towards the synthesis of a building block suitable for solid‐phase peptide synthesis were developed: a chemoenzymatic route, involving L ‐threonine aldolase, and an enantioselective chemical route; these led to α,γ‐diamino‐β‐hydroxybutanoic acids in diastereoisomerically mixed and enantiopure forms, respectively. Incorporation of the 1,2‐amino alcohol linker into the backbone of a peptide generated a conditional peptide that was rapidly cleaved at very low concentrations of sodium periodate. This cleavable peptide ligand was applied in the generation of MHC exchange reagents for the detection of antigen‐specific T cells in peripheral blood cells. The extremely low concentration of periodate required to trigger MHC peptide exchange allowed the co‐oxidation of methionine and disulfide residues to be avoided. Conditional MHC reagents hypersensitive to periodate can now be applied without limitations when UV irradiation is undesired or less practical.     

Activation of the glmS Ribozyme Confers Bacterial Growth Inhibition

The ever‐growing number of pathogenic bacteria resistant to treatment with antibiotics call for the development of novel compounds with as‐yet unexplored modes of action. Here, we demonstrate the in vivo antibacterial activity of carba‐α‐d ‐glucosamine (CGlcN). In this mode of action study, we provide evidence that CGlcN‐mediated growth inhibition is due to glmS ribozyme activation, and we demonstrate that CGlcN hijacks an endogenous activation pathway, hence utilizing a prodrug mechanism. This is the first report describing antibacterial activity mediated by activating the self‐cleaving properties of a ribozyme. Our results open the path towards a compound class with an entirely novel and distinct molecular mechanism.     

An Integrated Approach to Security on Demand in ATM Networks

Abstract

With the increasing use of Web services, many new challenges concerning data security are becoming critical. Especially in mobile services, where clients are generally thin in terms of computation power and storage space, a remote server can be outsourced for the computation or can act as a data store. Unfortunately, such a data store may not always be trustworthy, and clients with sensitive data and queries may want protection from malicious attacks. This article presents a technique to hide tree-structured data from potentially malicious data stores, while allowing clients to traverse the data to locate an object of interest without leaking information to the data store. The two motivating applications for this approach are hiding (1) tree-like XML data as well as XML queries that are in the form of tree-paths, and (2) tree-structured indexes and queries executed on such data structures. We show that this task is achievable through a one-server protocol that introduces only a limited and adjustable communication overhead. This is especially essential in low-bandwidth (such as wireless) distributed environments. The proposed protocol has desirable communication and concurrency performance, as demonstrated by the experiments we have conducted.     

Distributed algorithms for lifetime maximization in sensor networks via Min–Max spanning subgraphs

We consider the problem of static transmission-power assignment for lifetime maximization of a wireless sensor network with stationary nodes operating in a data-gathering scenario. Using a graph-theoretic approach, we propose two distributed algorithms, MLS and BSpan, that construct spanning trees with minimum maximum (minmax) edge cost. MLS is based on computation of minmax-cost paths from a reference node, while BSpan performs a binary search over the range of power levels and exploits the wireless broadcast advantage. We also present a simple distributed method for pruning a graph to its Relative Neighborhood Graph, which reduces the worst-case message complexity of MLS under natural assumptions on the path-loss. In our network simulations both MLS and BSpan significantly outperform the recently proposed Distributed Min–Max Tree algorithm in terms of number of messages required.     

Robust design considering highly nonlinear structural behavior

The optimization of structures subject to highly nonlinear behavior, particularly crash structures, requires observance of all design-significant scatterings. This paper presents a time-saving method to generate structures satisfying robust design demands. A vital aspect of robust design from the aircraft industries’ point of view is the consideration of fail-safe approaches accounting for possible structural failure from previous loading or manufacturing inaccuracies. Additional structural elements are utilized to prevent (after failure occurred) the structure from deforming out of bounds. This paper presents an approach on how to include this in the robust design process.     

Regulation of the expression of peripheral benzodiazepine receptors and their endogenous ligands during rat sciatic nerve degeneration and regeneration: a role for PBR in neurosteroidogenesis

This study addresses (1) the relationship between headache presence/intensity at time of testing and neurocognitive performance, and (2) the probability that testing triggers or intensifies pain. Subjects were 125 patients with chronic posttraumatic headache (mean = 2.67 years post injury) who completed a 4-hour test battery emphasizing memory. Comparisons of 34 individual tests/subtests and the five Wechsler Memory Scale-Revised (WMS-R) indices of relative memory impairment for 73 patients with no headache or mild headache versus 52 patients with moderate to severe pain revealed no significant differences. Testing intensified existing headaches for 55% but triggered headache for only 1 of 20 (5%; P =.00003). Results support the validity of neuropsychological test performance regardless of pain level, although testing can be painful.     

Variations of the frontal exit of the supraorbital nerve: an anatomic study

Meningeal worm (Parelaphostrongylus tenuis) is a neurotropic nematode of ungulates in eastern North America. Lack of an effective diagnostic test increases the concern of translocating potentially infected ungulates into western North America, where P. tenuis does not occur naturally. In an attempt to identify serodiagnostic molecules, we determined (1) whether elk (Cervus elaphus) experimentally infected with P. tenuis produce antibodies against infective larvae or adult worms, and (2) if sera consistently recognize antigens that distinguish P. tenuis from a common nematode parasite of elk, the lungworm Dictyocaulus viviparus. Each of 10 elk were exposed to 15 or 300 infective P. tenuis larvae. Serum was collected (0, 41, and 83 days post-exposure and at necropsy) and monitored for antibodies using the enzyme-linked immunosorbent assay (ELISA) and immunoblot. When reactivity of sera with larval P. tenuis protein was compared (day 0 versus 83), ELISA values were significantly higher on day 83 for elk exposed to 15 or 300 parasites. Likewise, ELISA values using protein of adult P. tenuis were higher for elk exposed to 300 larvae. Immunoblots showed that sera from elk, with adult worms in the central nervous system, consistently recognized the 25-27, 28-30, and 34-36 kDa antigens of infective larvae after 83 days. However, many D. viviparus molecules were found to cross-react with antibodies formed against meningeal worm antigens. Use of adult worm proteins for serodiagnosis appears limited, because no protein was consistently recognized by sera collected from elk exposed to 15 larvae. We believe that development of a reliable diagnostic test for meningeal worm requires more research addressing cross-reactivity and detection of P. tenuis during the incubation stage.