Aromatic oligoesters as novel helix mimetic scaffolds.

The design, synthesis, and conformational analysis of a novel aromatic oligoester helix mimetic scaffold is reported. A range of amino acid-type side-chain functionality can be readily incorporated into monomer building blocks over three facile synthetic steps. Analysis of representative dimers revealed a stable conformer capable of effective mimicry of a canonical α-helix and the scaffold was found to be surprisingly stable to degradation in aqueous solutions at acidic and neutral pH.

Thirsty work: Exploring children's experiences of preoperative fasting.

BACKGROUND: Preoperative fasting is performed to reduce aspiration risk during general anesthesia. Recommendations are that patients should fast for 6 hours from solids and nonhuman milk, 4 hours from breast milk, and 2 hours from clear fluids. However, previous studies have shown that children fast far in excess of these times, which can result in perioperative complications and unnecessary discomfort for the child. AIMS: This prospective, mixed-methods study aims to explore the experiences of pediatric patients undergoing preoperative fasting in Leeds General Infirmary. It also aims to investigate fasting durations of these patients and factors which influence these. METHODS: Over 2 weeks, surveys were distributed to all parents of elective pediatric patients and completed prior to their child being called to theater. Children over the age of six were offered a child survey, which had been specifically developed for the study, with visual Likert scales and an area for free text. The gathering of children's comments about their experience of preoperative fasting is unique to this study. RESULTS: Seventy-one parent surveys and 48 child surveys were completed, with a mean patient age of 8.3 years (SD 4.1). The mean preoperative fasting time for food was 11.7 hours (SD 4.4) and 6.9 hours (SD 5.0) for fluids. Fasting times were far in excess of the minimums recommended, negatively impacting patient experience with 34% reporting being hungry/very hungry and 19% thirsty/very thirsty. Most children's comments suggested that they coped well with the fasting; however, several children reported feelings of sadness and anxiety. CONCLUSION: Preoperative fasting times in pediatric patients far exceed the durations set by international guidelines. Given that many children reported extreme feelings of hunger and thirst or emotional effects from the fast, these durations need to be optimized in order to improve patient experience.

Probing Protein Surfaces: QSAR Analysis with Helix Mimetics.

α-Helix-mediated protein-protein interactions (PPIs) are important targets for small-molecule inhibition; however, generic approaches to inhibitor design are in their infancy and would benefit from QSAR analyses to rationalise the noncovalent basis of molecular recognition by designed ligands. Using a helix mimetic based on an oligoamide scaffold, we have exploited the power of a modular synthesis to access compounds that can readily be used to understand the noncovalent determinants of hDM2 recognition by this series of cell-active p53/hDM2 inhibitors.

Multivalent helix mimetics for PPI-inhibition.

The exploitation of multivalent ligands for the inhibition of protein-protein interactions has not yet been explored as a supramolecular design strategy. This is despite the fact that protein-protein interactions typically occur within the context of multi-protein complexes and frequently exploit avidity effects or co-operative binding interactions to achieve high affinity interactions. In this paper we describe preliminary studies on the use of a multivalent N-alkylated aromatic oligoamide helix mimetic for inhibition of p53/hDM2 and establish that protein dimerisation is promoted, rather than enhanced binding resulting from a higher effective concentration of the ligand.

Selective and potent proteomimetic inhibitors of intracellular protein-protein interactions.

Inhibition of protein-protein interactions (PPIs) represents a major challenge in chemical biology and drug discovery. α-Helix mediated PPIs may be amenable to modulation using generic chemotypes, termed "proteomimetics", which can be assembled in a modular manner to reproduce the vectoral presentation of key side chains found on a helical motif from one partner within the PPI. In this work, it is demonstrated that by using a library of N-alkylated aromatic oligoamide helix mimetics, potent helix mimetics which reproduce their biophysical binding selectivity in a cellular context can be identified.

Double-degradable responsive self-assembled multivalent arrays--temporary nanoscale recognition between dendrons and DNA.

This article reports self-assembling dendrons which bind DNA in a multivalent manner. The molecular design directly impacts on self-assembly which subsequently controls the way these multivalent nanostructures bind DNA--this can be simulated by multiscale modelling. Incorporation of an S-S linkage between the multivalent hydrophilic dendron and the hydrophobic units responsible for self-assembly allows these structures to undergo triggered reductive cleavage, with dithiothreitol (DTT) inducing controlled breakdown, enabling the release of bound DNA. As such, the high-affinity self-assembled multivalent binding is temporary. Furthermore, because the multivalent dendrons are constructed from esters, a second slow degradation step causes further breakdown of these structures. This two-step double-degradation mechanism converts a large self-assembling unit with high affinity for DNA into small units with no measurable binding affinity--demonstrating the advantage of self-assembled multivalency (SAMul) in achieving highly responsive nanoscale binding of biological targets.

Orthogonal functionalisation of α-helix mimetics.

α-Helix mediated protein-protein interactions are of major therapeutic importance. As such, the design of inhibitors of this class of interaction is of significant interest. We present methodology to modify N-alkylated aromatic oligoamide α-helix mimetics using 'click' chemistry. The effect is shown to modulate the binding properties of a series of selective p53/hDM2 inhibitors.

Mallard blue: a high-affinity selective heparin sensor that operates in highly competitive media.

We report the simple synthesis and full investigation of a novel heparin binding dye, mallard blue, an arginine-functionalized thionine. This dye binds heparin in highly competitive media, including water with high levels of competitive electrolyte, buffered aqueous solution and human serum. The dye reports on heparin levels by a significant change in its UV-vis spectroscopic profile. Molecular dynamics modeling provides detailed insight into the binding mode. Heparin binding is shown to be selective over other glycosaminoglycans, such as hyaluronic acid and chondroitin sulfate. Importantly, we demonstrate that, in the most competitive conditions, mallard blue outperforms standard dyes used for heparin sensing such as azure A.

In Situ Simulation Training for Frailty.

BACKGROUND: People living with frailty account for a significant proportion of hospital inpatients and are at increased risk of adverse events during admission. The understanding of frailty remains variable among hospital staff, and there is a need for effective frailty training across multidisciplinary teams. Simulation is known to be advantageous for improving human factor skills in multidisciplinary teams. In situ simulation can increase accessibility and promote ward team learning, but its effectiveness with respect to frailty has not been explored. METHOD: A single-centre, multi-fidelity, inter-professional in situ frailty simulation programme was developed. One-hour sessions were delivered weekly using frailty-based clinical scenarios. Mixed-method evaluation was used, with data collected pre- and post-session for comparison. RESULTS: In total, 86 multidisciplinary participants attended 19 sessions. There were significant improvements in self-efficacy rating across 10 of 12 human factor domains and in all frailty domains (p < 0.05). The common learning themes were situational awareness, communication and teamwork. Participants commented on the value of learning within ward teams and having the opportunity to debrief. CONCLUSION: In situ simulation can improve the self-efficacy of clinical and human factor skills related to frailty. The results are limited by the nature of self-reporting methods, and further studies assessing behavioural change and clinical outcomes are warranted.

Stapled Phd Peptides Inhibit Doc Toxin Induced Growth Arrest in Salmonella.

Bacterial toxin inhibition is a promising approach to overcoming antibiotic failure. InSalmonella, knockout of the toxin Doc has been shown to significantly reduce the formation of antibiotic-tolerant persisters. Doc is a kinase that is inhibited in nontolerant cells by its cognate antitoxin, Phd. In this work, we have developed first-in-class stapled peptide antitoxin mimetics based on the Doc inhibitory sequence of Phd. After making a series of substitutions to improve bacterial uptake, we identified a lead stapled Phd peptide that is able to counteract Doc toxicity in Salmonella. This provides an exciting starting point for the further development of therapeutic peptides capable of reducing antibiotic persistence in pathogenic bacteria.

A novel class of sulphonamides potently block malaria transmission by targeting a Plasmodium vacuole membrane protein.

Phenotypic cell-based screens are critical tools for discovering candidate drugs for development, yet identification of the cellular target and mode of action of a candidate drug is often lacking. Using an imaging-based screen, we recently discovered an N-[(4-hydroxychroman-4-yl)methyl]-sulphonamide (N-4HCS) compound, DDD01035881, that blocks male gamete formation in the malaria parasite life cycle and subsequent transmission of the parasite to the mosquito with nanomolar activity. To identify the target(s) of DDD01035881, and of the N-4HCS class of compounds more broadly, we synthesised a photoactivatable derivative, probe 2. Photoaffinity labelling of probe 2 coupled with mass spectrometry identified the 16 kDa Plasmodium falciparum parasitophorous vacuole membrane protein Pfs16 as a potential parasite target. Complementary methods including cellular thermal shift assays confirmed that the parent molecule DDD01035881 stabilised Pfs16 in lysates from activated mature gametocytes. Combined with high-resolution, fluorescence and electron microscopy data, which demonstrated that parasites inhibited with N-4HCS compounds phenocopy the targeted deletion of Pfs16 in gametocytes, these data implicate Pfs16 as a likely target of DDD01035881. This finding establishes N-4HCS compounds as being flexible and effective starting candidates from which transmission-blocking antimalarials can be developed in the future.

Effects of a PEG additive on the biomolecular interactions of self-assembled dendron nanostructures.

The ability of self-assembling multivalent DNA-binding dendrons to interact with biological targets is modified by co-assembly with two novel low-molecular-weight cholesterol-functionalised PEG units, one based on triethylene glycol (Chol-PEG-3) and one on an octaethylene glycol (Chol-PEG-8). The addition of either PEG lipid affected the co-assembled nanostructure surface charge and size in different ways depending on the structure of the self-assembling DNA-binding dendron. Co-assembly with Chol-PEG-8 enhanced DNA binding, while Chol-PEG-3 inhibited it. Insertion of Chol-PEG-8 into the aggregates modified their ability to cross a model mucus layer, the details of which can be understood in terms of a balance between the mucoadhesivity due to the surface charge of the nanoscale aggregates and that due to the PEG groups. This study demonstrates that the interaction of nanoscale assemblies with biological systems depends on a number of different factors in a sometimes unpredictable way. Given how simply multiple building blocks can be combined by self-assembly, we conclude that self-assembled multivalent systems have great potential for optimisation to maximise their biological and clinical activity.

Self-assembled multivalency: dynamic ligand arrays for high-affinity binding.

Multivalency is a powerful strategy for achieving high-affinity molecular recognition in biological systems. Recently, attention has begun to focus on using self-assembly rather than covalent scaffold synthesis to organize multiple ligands. This approach has a number of advantages, including ease of synthesis/assembly, tunability of nanostructure morphology and ligands, potential to incorporate multiple active units, and the responsive nature of self-assembly. We suggest that self-assembled multivalency is a strategy of fundamental importance in the design of synthetic nanosystems to intervene in biological pathways and has potential applications in nanomedicine.

Characterization of the Key Determinants of Phd Antitoxin Mediated Doc Toxin Inactivation in Salmonella.

In the search for novel antimicrobial therapeutics, toxin-antitoxin (TA) modules are promising yet underexplored targets for overcoming antibiotic failure. The bacterial toxin Doc has been associated with the persistence of Salmonella in macrophages, enabling its survival upon antibiotic exposure. After developing a novel method to produce the recombinant toxin, we have used antitoxin-mimicking peptides to thoroughly investigate the mechanism by which its cognate antitoxin Phd neutralizes the activity of Doc. We reveal insights into the molecular detail of the Phd-Doc relationship and discriminate antitoxin residues that stabilize the TA complex from those essential for inhibiting the activity of the toxin. Coexpression of Doc and antitoxin peptides in Salmonella was able to counteract the activity of the toxin, confirming our in vitro results with equivalent sequences. Our findings provide key principles for the development of chemical tools to study and therapeutically interrogate this important class of protein-protein interactions.

Degradable self-assembling dendrons for gene delivery: experimental and theoretical insights into the barriers to cellular uptake.

This paper uses a combined experimental and theoretical approach to gain unique insight into gene delivery. We report the synthesis and investigation of a new family of second-generation dendrons with four triamine surface ligands capable of binding to DNA, degradable aliphatic-ester dendritic scaffolds, and hydrophobic units at their focal points. Dendron self-assembly significantly enhances DNA binding as monitored by a range of experimental methods and confirmed by multiscale modeling. Cellular uptake studies indicate that some of these dendrons are highly effective at transporting DNA into cells (ca. 10 times better than poly(ethyleneimine), PEI). However, levels of transgene expression are relatively low (ca. 10% of PEI). This indicates that these dendrons cannot navigate all of the intracellular barriers to gene delivery. The addition of chloroquine indicates that endosomal escape is not the limiting factor in this case, and it is shown, both experimentally and theoretically, that gene delivery can be correlated with the ability of the dendron assemblies to release DNA. Mass spectrometric assays demonstrate that the dendrons, as intended, do degrade under biologically relevant conditions over a period of hours. Multiscale modeling of degraded dendron structures suggests that complete dendron degradation would be required for DNA release. Importantly, in the presence of the lower pH associated with endosomes, or when bound to DNA, complete degradation of these dendrons becomes ineffective on the transfection time scale-we propose this explains the poor transfection performance of these dendrons. As such, this paper demonstrates that taking this kind of multidisciplinary approach can yield a fundamental insight into the way in which dendrons can navigate barriers to cellular uptake. Lessons learned from this work will inform future dendron design for enhanced gene delivery.

What you need to know about falls.

Falls are a common presenting complaint, particularly in older patients, and are associated with significant morbidity. Inpatient falls also have financial implications for healthcare systems, including litigation costs. This article provides an approach to assessing a patient presenting with a fall, encompassing the cause and consequence of the event. It also highlights the need to consider both the acute and chronic factors that predispose a particular patient to fall. Chronic factors such as frailty, sarcopenia, cognitive impairment, and continence issues are often under-recognised and, as a result, not managed optimally. A comprehensive geriatric assessment is an ideal structure to identify modifiable risks. Practical interventions that can be of benefit to minimise a patient's risk of falling include a medication review, assessment of their mobility and their environment. In addition, continence review and visual assessment may be appropriate.

Modulators of protein-protein interactions as antimicrobial agents.

Protein-Protein interactions (PPIs) are involved in a myriad of cellular processes in all living organisms and the modulation of PPIs is already under investigation for the development of new drugs targeting cancers, autoimmune diseases and viruses. PPIs are also involved in the regulation of vital functions in bacteria and, therefore, targeting bacterial PPIs offers an attractive strategy for the development of antibiotics with novel modes of action. The latter are urgently needed to tackle multidrug-resistant and multidrug-tolerant bacteria. In this review, we describe recent developments in the modulation of PPIs in pathogenic bacteria for antibiotic development, including advanced small molecule and peptide inhibitors acting on bacterial PPIs involved in division, replication and transcription, outer membrane protein biogenesis, with an additional focus on toxin-antitoxin systems as upcoming drug targets.

A randomized controlled trial of real versus sham acupuncture for basal thumb joint arthritis.

We report a single-blinded randomized controlled trial comparing acupuncture to sham (non-penetrating) needling for relief of symptoms of basal thumb joint arthritis. Seventy acupuncture naive patients with basal thumb joint arthritis were randomized to receive true acupuncture or sham needling with 35 patients in each arm. Blinded baseline and post-treatment assessments included visual analogue pain scores for different grips and movement. Function was assessed using the Nelson questionnaire. Both groups showed statistically and clinically significant improvements in pain at week one post-treatment compared with baseline, but there was no difference between the treatment groups. The pain relief was comparable with published data for some standard treatments. Acupuncture did not perform better than sham needling in this study, indicating that pain relief may have been achieved through non-specific mechanisms. Level of evidence: I.

Structure-Activity Relationship Studies of a Novel Class of Transmission Blocking Antimalarials Targeting Male Gametes.

Malaria is still a leading cause of mortality among children in the developing world, and despite the immense progress made in reducing the global burden, further efforts are needed if eradication is to be achieved. In this context, targeting transmission is widely recognized as a necessary intervention toward that goal. After carrying out a screen to discover new transmission-blocking agents, herein we report our medicinal chemistry efforts to study the potential of the most robust hit, DDD01035881, as a male-gamete targeted compound. We reveal key structural features for the activity of this series and identify analogues with greater potency and improved metabolic stability. We believe this study lays the groundwork for further development of this series as a transmission blocking agent.

Enantioselective lactate binding by chiral tripodal anion hosts derived from amino acids.

Chiral, tripodal anion hosts derived from either S-phenylalanine or S-leucine bind D-lactate enantioselectively. The nature of the host-guest interaction has been probed by solution NMR methods and by DFT calculations. The calculations suggest that the D-lactate may form an additional hydrogen bond in the host-guest complex while the L-lactate complex contains an intramolecular hydrogen bond. Anion binding is in competition with host dimerisation, as demonstrated by DOSY and (1)H NMR spectroscopy, and DFT calculations.