Ultrafast Au(III)-Mediated Arylation of Cysteine.

Through mechanistic work and rational design, we have developed the fastest organometallic abiotic Cys bioconjugation. As a result, the developed organometallic Au(III) bioconjugation reagents enable selective labeling of Cys moieties down to picomolar concentrations and allow for the rapid construction of complex heterostructures from peptides, proteins, and oligonucleotides. This work showcases how organometallic chemistry can be interfaced with biomolecules and lead to a range of reactivities that are largely unmatched by classical organic chemistry tools.

Overlaps and trade-offs in the diversity and inducibility of volatile chemical profiles among diverse sympatric neotropical canopy trees.

A central goal in ecology is to understand the mechanisms by which biological diversity is maintained. The diversity of plant chemical defences and the strategies by which they are deployed in nature may influence biological diversity. Trees in neotropical forests are subject to relatively high herbivore pressure. Such consistent pressure is thought to select for constitutive, non-flexible defence-related phytochemistry with limited capacity for inducible phytochemical responses. However, this has not been explored for volatile organic compounds (VOCs) that have a relatively low ratio of production costs to ecological benefits. To test this, I sampled VOCs emitted from canopy leaves of 10 phylogenetically diverse tree species (3 Magnoliids and 7 Rosids) in the Peruvian Amazon before and after induction with the phytohormone methyl jasmonate (MeJA). There was no phylogenetic signal in induction or magnitude of MeJA-induced VOC emissions from intact leaves: all trees induced VOC profiles dominated by ß-ocimene, linalool, and α-farnesene of varying ratios. Moreover, overall inducibility of VOCs from intact leaves was unrelated to phytochemical diversity or richness. In contrast, experimentally wounded leaves showed considerable phylogeny-based and MeJA-independent variation the richness and diversity of constitutive wound-emitted VOCs. Moreover, VOC inducibility from wounded leaves correlated negatively with phytochemical richness and diversity, potentially indicating a tradeoff in constitutive and inducible defence strategies for non-volatile specialised metabolites but not for inducible VOCs. Importantly, there was no correlation between any chemical profile and either natural herbivory or leaf toughness. The coexistence of multiple phytochemical strategies in a hyper-diverse forest has broad implications for competitive and multitrophic interactions, and the evolutionary forces that maintain the exceptional plant biodiversity in neotropical forests.

Pd(II)-Mediated C-H Activation for Cysteine Bioconjugation.

Selective bioconjugation remains a significant challenge for the synthetic chemist due to the stringent reaction conditions required by biomolecules coupled with their high degree of functionality. The current trailblazer of transition-metal mediated bioconjugation chemistry involves the use of Pd(II) complexes prepared via an oxidative addition process. Herein, the preparation of Pd(II) complexes for cysteine bioconjugation via a facile C-H activation process is reported. These complexes show bioconjugation efficiency competitive with what is seen in the current literature, with a user-friendly synthesis, common Pd(II) sources, and a more cost-effective ligand. Furthermore, these complexes need not be isolated, and still achieve high conversion efficiency and selectivity of a model peptide. These complexes also demonstrate the ability to selectively arylate a single surface cysteine residue on a model protein substrate, further demonstrating their utility.

Stimuli responsive asymmetric catalysis by triggered pseudo-enantiomeric proligand release.

Complex stimuli responsive systems are the basis for molecular machines and computing. A dual psuedo-enantiomer system was conceived, where the combination of two 'switch-on' asymmetric catalytic cycles could be selectively triggered to afford an enantioenriched product. Two pseudo-enantiomeric proligands were designed and synthesised for selective activation by fluoride and alkaline phosphatase. The proligands were firstly incorporated into single proligand systems, and then into a dual proligand system, where enantioselectivity of up to 98 : 2 was achieved in the reduction of prochiral ketone following external stimulation.

Priming Seeds with Indole and (Z)-3-Hexenyl Acetate Enhances Resistance Against Herbivores and Stimulates Growth.

A striking feature of plant ecology is the ability of plants to detect and respond to environmental cues such as herbivore-induced plant volatiles (HIPVs) by priming or directly activating defenses against future herbivores. However, whether seeds also respond to compounds that are common constituents of HIPV blends and initiate future plant resistance is unknown. Considering that seeds depend on other environmental cues to determine basic survival traits such as germination timing, we predicted that seeds exposed to synthetic constituents of HIPV blends would generate well-defended plants. We investigated the effect of seed exposure to common volatiles on growth, reproduction, and resistance characteristics in the model plants Arabidopsis thaliana and Medicago truncatula using herbivores from two feeding guilds. After seed scarification and vernalization, we treated seeds with one of seven different plant-derived volatile compounds for 24 h. Seeds were then germinated and the resulting plants were assayed for growth, herbivore resistance, and expression of inducible defense genes. Of all the synthetic volatiles tested, indole specifically reduced both beet armyworm growth on A. thaliana and pea aphid fecundity on M. truncatula. The induction of defense genes was not affected by seed exposure to indole in either plant species, indicating that activation of direct resistance rather than inducible resistance is the mechanism by which seed priming operates. Moreover, neither plant species showed any negative effect of seed exposure to any synthetic volatile on vegetative and reproductive growth. Rather, M. truncatula plants derived from seeds exposed to (Z)-3-hexanol and (Z)-3-hexenyl acetate grew larger compared to controls. Our results indicate that seeds are sensitive to specific volatiles in ways that enhance resistance profiles with no apparent costs in terms of growth. Seed priming by HIPVs may represent a novel ecological mechanism of plant-to-plant interactions, with broad potential applications in agriculture and seed conservation.

Ratiometric Electrochemistry: Improving the Robustness, Reproducibility and Reliability of Biosensors.

Electrochemical biosensors are an increasingly attractive option for the development of a novel analyte detection method, especially when integration within a point-of-use device is the overall objective. In this context, accuracy and sensitivity are not compromised when working with opaque samples as the electrical readout signal can be directly read by a device without the need for any signal transduction. However, electrochemical detection can be susceptible to substantial signal drift and increased signal error. This is most apparent when analysing complex mixtures and when using small, single-use, screen-printed electrodes. Over recent years, analytical scientists have taken inspiration from self-referencing ratiometric fluorescence methods to counteract these problems and have begun to develop ratiometric electrochemical protocols to improve sensor accuracy and reliability. This review will provide coverage of key developments in ratiometric electrochemical (bio)sensors, highlighting innovative assay design, and the experiments performed that challenge assay robustness and reliability.

A non-catalytic function of carbonic anhydrase IX contributes to the glycolytic phenotype and pH regulation in human breast cancer cells.

The most aggressive and invasive tumor cells often reside in hypoxic microenvironments and rely heavily on rapid anaerobic glycolysis for energy production. This switch from oxidative phosphorylation to glycolysis, along with up-regulation of the glucose transport system, significantly increases the release of lactic acid from cells into the tumor microenvironment. Excess lactate and proton excretion exacerbate extracellular acidification to which cancer cells, but not normal cells, adapt. We have hypothesized that carbonic anhydrases (CAs) play a role in stabilizing both intracellular and extracellular pH to favor cancer progression and metastasis. Here, we show that proton efflux (acidification) using the glycolytic rate assay is dependent on both extracellular pH (pHe) and CA IX expression. Yet, isoform-selective sulfonamide-based inhibitors of CA IX did not alter proton flux, which suggests that the catalytic activity of CA IX is not necessary for this regulation. Other investigators have suggested the CA IX co-operates with the MCT transport family to excrete protons. To test this possibility, we examined the expression patterns of selected ion transporters and show that members of this family are differentially expressed within the molecular subtypes of breast cancer. The most aggressive form of breast cancer, triple-negative breast cancer, appears to co-ordinately express the monocarboxylate transporter 4 (MCT4) and carbonic anhydrase IX (CA IX). This supports a possible mechanism that utilizes the intramolecular H+ shuttle system in CA IX to facilitate proton efflux through MCT4.

Atypical Mycobacterial Infections After Plastic Surgery Procedures Abroad: A Multidisciplinary Algorithm for Diagnosis and Treatment.

BACKGROUND: The recent rise in medical tourism, especially for cosmetic procedures, has been mirrored by an increase in the incidence of infections with Mycobacterium abscessus, which is an atypical mycobacterium that is ubiquitous in aquatic environments. M. abscessus soft tissue infections arise from the use of improperly sterilized water and surgical equipment during surgical procedures, and these infections have devastating consequences if not promptly treated. M. abscessus infections are notoriously difficult to diagnose and properly treat, and therefore, we illustrate a typical case presentation and provide a comprehensive diagnostic and treatment algorithm. METHODS: Of the patients who have presented to our hospital for treatment of cutaneous M. abscessus infections, a representative patient's story was included to illustrate the typical presentation and treatment timeline. The current literature on M. abscessus infections was reviewed, and this literature and the clinical experience of our plastic surgery and infectious disease teams were used in the creation of a diagnostic and treatment algorithm for M. abscessus infections. RESULTS: M. abscessus infections can have an incubation period of months, and the classic presenting signs include purulent drainage, violaceous nodules, and subcutaneous abscesses at the site of a recent surgery. A key finding is persistence of the infection despite debridement and empiric antibiotic treatment. Cultures grown on mycobacterial-specific growth media are considered the diagnostic criterion standard, but high clinical suspicion is enough to warrant the initiation of treatment. Treatment itself consists of surgical drainage and debridement in combination with multidrug antibiotic regimens that typically include amikacin, a macrolide, and a carbapenem or cephalosporin antibiotic, with the option for macrolide and fluoroquinolone maintenance therapy. CONCLUSIONS: M. abscessus cutaneous infections present with unique history and physical examination findings and often require complex diagnostic workups and treatment plans. Increased provider awareness of the management and potential complications of M. abscessus is crucial to the improvement patient outcomes, as is a multidisciplinary approach that incorporates primary care providers, pathologists, plastic surgeons, and infectious disease specialists.

Latissimus Denervation: A Review of Evidence.

BACKGROUND: Breast reconstruction is becoming an increasingly important and accessible component of breast cancer care. Among the many reconstructive options available, the latissimus dorsi flap has experienced a renewal in popularity because of its favorable properties and outcomes when used for breast reconstruction. However, a limitation unique to latissimus-based reconstruction is inappropriate breast animation postoperatively, due to persistent thoracodorsal innervation of the latissimus dorsi muscle after transfer to the mastectomy site. METHODS: A comprehensive literature search of PubMed and MEDLINE was conducted for studies investigating the role of thoracodorsal denervation in latissimus-based breast reconstruction. Data on surgical techniques, type of intervention, objective outcome measurements, and patient satisfaction-based outcomes were reported. Additional data included patient sample size, follow-up length, and treatment of thoracodorsal nerve (e.g., resection versus transection and length of transection) when applicable. RESULTS: Sixty-six search results were reviewed for inclusion and nine qualified after exclusion criteria for a total of 361 patients undergoing either unilateral or bilateral latissimus flap reconstruction. Successful thoracodorsal denervation rates were included in most studies and outcomes measurements were heterogeneous. Eight out of nine studies included patient-reported symptoms of breast animation postoperatively. Based on these findings, a systematic approach is presented. CONCLUSION: We present this review to elucidate successful practices, identify current gaps in knowledge, and offer a systematic approach to this clinical challenge.

Management of Bilateral Edentulous Mandible Fractures Through an Intraoral Approach Using CAD/CAM Technology: A Case Report.

The surgical management of edentulous mandible fractures presents unique challenges secondary to poor bone stock and the absence of dentition to assist with fracture reduction. In complex injury patterns, such as bilateral edentulous mandible fractures, an external approach is often necessary to achieve adequate reduction and adaptation of a load-bearing reconstruction plate. We report a case in which computer-assisted design/computer-assisted manufacturing (CAD/CAM) was applied as an adjunct for the acute management of bilateral edentulous mandible fractures in a 58-year-old man. CAD/CAM technology was used to fabricate a patient-specific reconstruction plate and a maxillomandibular splint, which facilitated the successful treatment of this complex injury through an intraoral approach. This case highlights the potential of CAD/CAM technology to improve operative efficiency and clinical outcomes in the acute management of complex edentulous mandible fractures.

Regenerative peripheral nerve interfaces for real-time, proportional control of a Neuroprosthetic hand.

INTRODUCTION: Regenerative peripheral nerve interfaces (RPNIs) are biological constructs which amplify neural signals and have shown long-term stability in rat models. Real-time control of a neuroprosthesis in rat models has not yet been demonstrated. The purpose of this study was to: a) design and validate a system for translating electromyography (EMG) signals from an RPNI in a rat model into real-time control of a neuroprosthetic hand, and; b) use the system to demonstrate RPNI proportional neuroprosthesis control. METHODS: Animals were randomly assigned to three experimental groups: (1) Control; (2) Denervated, and; (3) RPNI. In the RPNI group, the extensor digitorum longus (EDL) muscle was dissected free, denervated, transferred to the lateral thigh and neurotized with the residual end of the transected common peroneal nerve. Rats received tactile stimuli to the hind-limb via monofilaments, and electrodes were used to record EMG. Signals were filtered, rectified and integrated using a moving sample window. Processed EMG signals (iEMG) from RPNIs were validated against Control and Denervated group outputs. RESULTS: Voluntary reflexive rat movements produced signaling that activated the prosthesis in both the Control and RPNI groups, but produced no activation in the Denervated group. Signal-to-Noise ratio between hind-limb movement and resting iEMG was 3.55 for Controls and 3.81 for RPNIs. Both Control and RPNI groups exhibited a logarithmic iEMG increase with increased monofilament pressure, allowing graded prosthetic hand speed control (R2 = 0.758 and R2 = 0.802, respectively). CONCLUSION: EMG signals were successfully acquired from RPNIs and translated into real-time neuroprosthetic control. Signal contamination from muscles adjacent to the RPNI was minimal. RPNI constructs provided reliable proportional prosthetic hand control.

Ruthenium-catalysed σ-activation for remote meta-selective C-H functionalisation.

The search for selective C-H functionalisation has enabled some of the most elegant techniques in modern catalysis. Herein, we review the rapidly expanding field of ruthenium catalysed σ-activation as a tool in the selective meta-C-H functionalisation of arenes.

Ratiometric electrochemical detection of hydrogen peroxide and glucose.

Hydrogen peroxide (H2O2) detection is of high importance as it is a versatile (bio)marker whose detection can indicate the presence of explosives, enzyme activity and cell signalling pathways. Herein, we demonstrate the rapid and accurate ratiometric electrochemical detection of H2O2 using disposable screen-printed electrodes through a reaction-based indicator assay. Ferrocene derivatives equipped with self-immolative linkers and boronic acid ester moieties were synthesised and tested, and, through a thorough assay optimisation, the optimum probe showed good stability, sensitivity and selectivity towards H2O2. The optimised conditions were then applied to the indirect detection of glucose via an enzymatic assay, capable of distinguishing 10 µM from the background within minutes.

Ratiometric electrochemical detection of ß-galactosidase.

A novel ferrocene-based substrate for the ratiometric electrochemical detection of ß-galactosidase was designed and synthesised. It was demonstrated to be an excellent electrochemical substrate for ß-Gal detection with sensitivity as low as 0.1 U mL-1.

α-Halo carbonyls enable meta selective primary, secondary and tertiary C-H alkylations by ruthenium catalysis.

A catalytic meta selective C-H alkylation of arenes is described using a wide range of α-halo carbonyls as coupling partners. Previously unreported primary alkylations with high meta selectivity have been enabled by this methodology whereas using straight chain alkyl halides affords ortho substituted products. Mechanistic analysis reveals an activation pathway whereby cyclometalation with a ruthenium(ii) complex activates the substrate molecule and is responsible for the meta selectivity observed. A distinct second activation of the coupling partner allows site selective reaction between both components.

Ruthenium-Catalyzed para-Selective C-H Alkylation of Aniline Derivatives.

The para-selective C-H alkylation of aniline derivatives furnished with a pyrimidine auxiliary is herein reported. This reaction is proposed to take place via an N-H-activated cyclometalate formed in situ. Experimental and DFT mechanistic studies elucidate a dual role of the ruthenium catalyst. Here the ruthenium catalyst can undergo cyclometalation by N-H metalation (as opposed to C-H metalation in meta-selective processes) and form a redox active ruthenium species, to enable site-selective radical addition at the para position.

Constitutively elevated salicylic acid levels alter photosynthesis and oxidative state but not growth in transgenic populus.

Salicylic acid (SA) has long been implicated in plant responses to oxidative stress. SA overproduction in Arabidopsis thaliana leads to dwarfism, making in planta assessment of SA effects difficult in this model system. We report that transgenic Populus tremula × alba expressing a bacterial SA synthase hyperaccumulated SA and SA conjugates without negative growth consequences. In the absence of stress, endogenously elevated SA elicited widespread metabolic and transcriptional changes that resembled those of wild-type plants exposed to oxidative stress-promoting heat treatments. Potential signaling and oxidative stress markers azelaic and gluconic acids as well as antioxidant chlorogenic acids were strongly coregulated with SA, while soluble sugars and other phenylpropanoids were inversely correlated. Photosynthetic responses to heat were attenuated in SA-overproducing plants. Network analysis identified potential drivers of SA-mediated transcriptome rewiring, including receptor-like kinases and WRKY transcription factors. Orthologs of Arabidopsis SA signaling components NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1 and thioredoxins were not represented. However, all members of the expanded Populus nucleoredoxin-1 family exhibited increased expression and increased network connectivity in SA-overproducing Populus, suggesting a previously undescribed role in SA-mediated redox regulation. The SA response in Populus involved a reprogramming of carbon uptake and partitioning during stress that is compatible with constitutive chemical defense and sustained growth, contrasting with the SA response in Arabidopsis, which is transient and compromises growth if sustained.

Use of the Hydantoin Directing Group in Ruthenium(II)-Catalyzed C-H Functionalization.

Ruthenium(II)-catalyzed C-H functionalization of N-arylhydantoins is herein described. The biologically relevant hydantoin (imidazolidinedione) heterocycle functions as a weakly coordinating directing group in a C-H alkenylation reaction. The reaction gave a wide scope of 23 examples with yields up to 94% in the green solvent 2-MeTHF. Functionalization of API nilutamide (antiandrogen) is also reported. The use of the succinimide heterocycle as a directing group is also demonstrated in modest yields.

Approaches towards molecular amplification for sensing.

Diagnostic assays that rely on molecular interactions have come a long way; from initial reversible detection systems towards irreversible reaction indicator-based methods. More recently, the emergence of innovative molecular amplification methodologies has revolutionised sensing, allowing diagnostic assays to achieve ultra-low limits of detection. There have been a significant number of molecular amplification approaches developed over recent years to accommodate the wide variety of analytes that require sensitive detection. To celebrate this achievement, this comprehensive critical review has been compiled to give a broad overview of the many different approaches used to attain amplification in sensing with an aim to inspire the next generation of diagnostic assays looking to achieve the ultimate detection limit. This review has been created with the focus on how each conceptually unique molecular amplification methodology achieves amplification, not just its sensitivity, while highlighting any key processes. Excluded are any references that were not found to contain an obvious molecular amplifier or amplification component, or that did not use an appropriate signal readout that could be incorporated into a sensing application. Additionally, methodologies where amplification is achieved through advances in instrumentation are also excluded. Depending upon the type of approach employed, amplification strategies are divided into four categories: target, label, signal or receptor amplification. More recent, more complex protocols combine a number of approaches and are therefore categorised by which amplification component described within was considered as the biggest advancement. The advantages and disadvantages of each methodology are discussed along with any limits of detection, if stated in the original article. Any subsequent use of the methodology within sensing or any other application is also mentioned to draw attention to its practicality. The importance of amplification within sensing is wholly emphasised while perspectives on the future direction of the field are also shared.