Miniaturisation of a peptide-based electrochemical protease activity sensor using platinum microelectrodes.

Proteases are ideal target biomarkers as they have been implicated in many disease states, including steps associated with cancer progression. Electrochemical peptide-based biosensors have attracted much interest in recent years. However, the significantly large size of the electrodes typically used in most of these platforms has led to performance limitations.

Enhanced avidity from a multivalent fluorescent antimicrobial peptide enables pathogen detection in a human lung model.

Rapid in situ detection of pathogens coupled with high resolution imaging in the distal human lung has the potential to provide new insights and diagnostic utility in patients in whom pneumonia is suspected. We have previously described an antimicrobial peptide (AMP) Ubiquicidin (fragment UBI) labelled with an environmentally sensitive fluorophore that optically detected bacteria in vitro but not ex vivo. Here, we describe further chemical development of this compound and demonstrate that altering the secondary structure of the AMP to generate a tri-branched dendrimeric scaffold provides enhanced signal in vitro and ex vivo and consequently allows the rapid detection of pathogens in situ in an explanted human lung.

In situ identification of Gram-negative bacteria in human lungs using a topical fluorescent peptide targeting lipid A.

Respiratory infections in mechanically ventilated patients caused by Gram-negative bacteria are a major cause of morbidity. Rapid and unequivocal determination of the presence, localization, and abundance of bacteria is critical for positive resolution of the infections and could be used for patient stratification and for monitoring treatment efficacy. Here, we developed an in situ approach to visualize Gram-negative bacterial species and cellular infiltrates in distal human lungs in real time.

Super-silent FRET Sensor Enables Live Cell Imaging and Flow Cytometric Stratification of Intracellular Serine Protease Activity in Neutrophils.

Serine proteases are released by neutrophils to act primarily as antimicrobial proteins but excessive and unbalanced serine protease activity results in serious host tissue damage. Here the synthesis of a novel chemical sensor based on a multi-branched fluorescence quencher is reported. It is super-silent, exhibiting no fluorescence until de-quenched by the exemplar serine protease human neutrophil elastase, rapidly enters human neutrophils, and is inhibited by serine protease inhibitors.

Searching for the Optimal Fluorophore to Label Antimicrobial Peptides.

With the advent of antimicrobial resistance, there is an urgent need for new strategies to treat infectious diseases. Antimicrobial peptides are considered as promising candidates, and therefore there is a need to understand their mechanism of action in order to exploit their therapeutic potential. To this end, fluorescent analogs are powerful tools to analyze their behavior and subcellular localization in cells and in vivo.

Red-Fluorescent Activatable Probes for the Detection of Hydrogen Peroxide in Living Cells.

Many inflammatory processes are associated with an increase in the production of reactive oxygen species (ROS). Chemical probes that specifically detect ROS are potentially useful tools for the early diagnosis of inflammatory diseases as well as cancer. Herein we have developed a library of coumarin hybrids by condensation of various heterocyclic quaternary salts to a 7-hydroxycoumarin scaffold.

Methylene blue not ferrocene: Optimal reporters for electrochemical detection of protease activity.

Electrochemical peptide-based biosensors are attracting significant attention for the detection and analysis of proteins. Here we report the optimisation and evaluation of an electrochemical biosensor for the detection of protease activity using self-assembled monolayers (SAMs) on gold surfaces, using trypsin as a model protease. The principle of detection was the specific proteolytic cleavage of redox-tagged peptides by trypsin, which causes the release of the redox reporter, resulting in a decrease of the peak current as measured by square wave voltammetry.

A labelled-ubiquicidin antimicrobial peptide for immediate optical detection of live bacteria in human alveolar lung tissue.

The immediate detection of the presence of bacteria in the distal human lung is of significant clinical utility. Herein we describe the development and optimization of a bacterial binding fragment (UBI) of the antimicrobial peptide, ubiquicidin (UBI), conjugated to an environmentally sensitive fluorophore to enable rapid live bacterial imaging within human lung tissue. UBI was modified for stability in the presence of human lung bronchoalveolar lavage fluid, for affinity to bacterial membranes and functionality in human lung tissue.

CD133+ cancer stem-like cells in small cell lung cancer are highly tumorigenic and chemoresistant but sensitive to a novel neuropeptide antagonist.

Small cell lung cancer (SCLC) is a highly aggressive malignancy with poor survival rates, with initial responses nearly invariably followed by rapid recurrence of therapy-resistant disease. Drug resistance in SCLC may be attributable to the persistence of a subpopulation of cancer stem-like cells (CSC) that exhibit multiple drug resistance. In this study, we characterized the expression of CD133, one important marker of CSC in other cancers, in SCLC cancer cells.

FeCl3-catalysed ultrasonic-assisted, solvent-free synthesis of 4-substituted coumarins. A useful complement to the Pechmann reaction.

The catalytic activity of FeCl3 for the synthesis of a variety of 4-substituted coumarins using high energy techniques has been investigated. The ultrasonic-assisted conditions provide a useful complement to the Pechmann reaction, affording the coumarin derivatives in excellent yields, under solvent-free conditions, in short reaction times using an inexpensive, mild and benign Lewis acid catalyst.

Highly specific, multi-branched fluorescent reporters for analysis of human neutrophil elastase.

Human neutrophil elastase (HNE) is a serine protease implicated in the pathogenesis of acute and chronic inflammatory disease. Here a series of, internally quenched, single fluorophore fluorescent reporters were synthesised that allowed the rapid, highly specific and sensitive analysis of HNE activity over closely related proteases.

Transcription forms and remodels supercoiling domains unfolding large-scale chromatin structures.

DNA supercoiling is an inherent consequence of twisting DNA and is critical for regulating gene expression and DNA replication. However, DNA supercoiling at a genomic scale in human cells is uncharacterized. To map supercoiling, we used biotinylated trimethylpsoralen as a DNA structure probe to show that the human genome is organized into supercoiling domains.

Neurosteroid dehydroepiandrosterone interacts with nerve growth factor (NGF) receptors, preventing neuronal apoptosis.

The neurosteroid dehydroepiandrosterone (DHEA), produced by neurons and glia, affects multiple processes in the brain, including neuronal survival and neurogenesis during development and in aging. We provide evidence that DHEA interacts with pro-survival TrkA and pro-death p75(NTR) membrane receptors of neurotrophin nerve growth factor (NGF), acting as a neurotrophic factor: (1) the anti-apoptotic effects of DHEA were reversed by siRNA against TrkA or by a specific TrkA inhibitor; (2) [(3)H]-DHEA binding assays showed that it bound to membranes isolated from HEK293 cells transfected with the cDNAs of TrkA and p75(NTR) receptors (K(D): 7.4 ± 1.

Synthesis, photolysis studies and in vitro photorelease of caged TRPV1 agonists and antagonists.

The synthesis of a range of caged TRPV1 agonists and antagonists is reported. The photolysis characteristics of these compounds, when irradiated with a 355 nm laser, have been studied and in all cases the desired compound was produced. Photolysis of a caged TRPV1 agonist in cultured trigeminal neurons produced responses that were consistent with the activation of TRPV1 receptors.

Novel dehydroepiandrosterone derivatives with antiapoptotic, neuroprotective activity.

DHEA analogues with modifications at positions C3 or C17 were synthesized and evaluated for neuroprotective activity against the neural-crest-derived PC12 cell model of serum deprivation-induced apoptosis. The most potent compounds were the spiro-epoxy derivatives 17beta-spiro[5-androstene-17,2'-oxiran]-3beta-ol (20), (20S)-3beta,21-dihydroxy-17beta,20-epoxy-5-pregnene (23), and (20R)-3beta,21-dihydroxy-17alpha,20-epoxy-5-pregnene (27) with IC(50) values of 0.19 +/- 0.

Caged AG10: new tools for spatially predefined mitochondrial uncoupling.

The study of mitochondria and mitochondrial Ca2+ signalling in localised regions is hampered by the lack of tools that can uncouple the mitochondrial membrane potential (DeltaPsi(m)) in a spatially predefined manner. Although there are a number of existing mitochondrial uncouplers, these compounds are necessarily membrane permeant and therefore exert their actions in a spatially unselective manner. Herein, we report the synthesis of the first caged (photolabile protected) mitochondrial uncouplers, based on the tyrphostin AG10.

Neuroprotective effects of steroid analogues on P19-N neurons.

Naturally occurring neurosteroids are potent allosteric modulators of gamma-aminobutyric acid(A) receptor and through augmentation of gamma-aminobutyric acid(A) receptor function, can protect neuronal cells against N-methyl-d-aspartate receptor over-activation, ischemia and traumatic brain injury. In this study, mouse P19 cells were induced to differentiate into post-mitotic neurons and were subjected to excitotoxicity in the presence of N-methyl-d-aspartate. Novel synthetic analogues of the endogenous neurosteroids allopregnanolone and dehydroepiandrostrone, inhibited excitotoxic cell death of P19-N neurons, by directly maintaining the activation of PKB/Akt kinase and interfering with the intrinsic mitochondrial apoptotic pathway, preserving cytochrome c in the mitochondria and Bax in the cytoplasm.

G protein-associated, specific membrane binding sites mediate the neuroprotective effect of dehydroepiandrosterone.

The neurosteroid dehydroepiandrosterone (DHEA) at 1 nM protects NMDA-/GABAA-receptor negative neural crest-derived PC12 cells from apoptosis. We now report that membrane-impermeable DHEA-BSA conjugate replaces unconjugated DHEA in protecting serum-deprived PC12 cells from apoptosis (IC50=1.5 nM).

Novel 17beta-substituted conformationally constrained neurosteroids that modulate GABA A receptors.

The goal of this study was to develop a series of allopregnanolone analogues substituted by conformationally constrained 17beta side chains to obtain additional information about the structure-activity relationship of 5alpha-reduced steroids to modulate GABA(A) receptors. Specifically, we introduced alkynyl-substituted 17beta side chains in which the triple bond is either directly attached to the 17beta-position or to the 21-position of the steroid skeleton. Furthermore, we investigated the effects of C22 and C20 modification.

Structure-activity relationships of antineoplastic ring-substituted ether phospholipid derivatives.

Purpose: Previous studies have shown that alkylphosphocholines (APCs) exhibit strong antineoplastic activity against various tumour cell lines in vitro and in several animal models. The current study was designed to investigate the influence of cycloalkane rings on the antiproliferative activity of APCs against a panel of eight human and animal cell lines (PC3, MCF7, A431, Hela, PC12, U937, K562, CHO). Specifically, we explored the effect of the presence of 4-alkylidenecyclohexyl and cycloalkylidene groups in alkoxyethyl and alkoxyphosphodiester ether lipids, respectively.