Structural and mechanistic basis for protein glutamylation by the kinase fold.

The kinase domain transfers phosphate from ATP to substrates. However, the Legionella effector SidJ adopts a kinase fold, yet catalyzes calmodulin (CaM)-dependent glutamylation to inactivate the SidE ubiquitin ligases. The structural and mechanistic basis in which the kinase domain catalyzes protein glutamylation is unknown. Here we present cryo-EM reconstructions of SidJ:CaM:SidE reaction intermediate complexes. We show that the kinase-like active site of SidJ adenylates an active-site Glu in SidE, resulting in the formation of a stable reaction intermediate complex. An insertion in the catalytic loop of the kinase domain positions the donor Glu near the acyl-adenylate for peptide bond formation. Our structural analysis led us to discover that the SidJ paralog SdjA is a glutamylase that differentially regulates the SidE ligases during Legionella infection. Our results uncover the structural and mechanistic basis in which the kinase fold catalyzes non-ribosomal amino acid ligations and reveal an unappreciated level of SidE-family regulation.

Metabolite-Sensing Receptor Ffar2 Regulates Colonic Group 3 Innate Lymphoid Cells and Gut Immunity.

Group 3 innate lymphoid cells (ILC3s) sense environmental signals that are critical for gut homeostasis and host defense. However, the metabolite-sensing G-protein-coupled receptors that regulate colonic ILC3s remain poorly understood. We found that colonic ILC3s expressed Ffar2, a microbial metabolite-sensing receptor, and that Ffar2 agonism promoted ILC3 expansion and function. Deficiency of Ffar2 in ILC3s decreased their in situ proliferation and ILC3-derived interleukin-22 (IL-22) production. This led to impaired gut epithelial function characterized by altered mucus-associated proteins and antimicrobial peptides and increased susceptibility to colonic injury and bacterial infection. Ffar2 increased IL-22+ CCR6+ ILC3s and influenced ILC3 abundance in colonic lymphoid tissues. Ffar2 agonism differentially activated AKT or ERK signaling and increased ILC3-derived IL-22 via an AKT and STAT3 axis. Our findings suggest that Ffar2 regulates colonic ILC3 proliferation and function, and they identify an ILC3-receptor signaling pathway modulating gut homeostasis and pathogen defense.

Monolithic piezoelectric control of soliton microcombs.

High-speed actuation of laser frequency1 is critical in applications using lasers and frequency combs2,3, and is a prerequisite for phase locking, frequency stabilization and stability transfer among optical carriers. For example, high-bandwidth feedback control of frequency combs is used in optical-frequency synthesis4, frequency division5 and optical clocks6. Soliton microcombs7,8 have emerged as chip-scale frequency comb sources, and have been used in system-level demonstrations9,10. Yet integrated microcombs using thermal heaters have limited actuation bandwidths11,12 of up to 10 kilohertz. Consequently, megahertz-bandwidth actuation and locking of microcombs have only been achieved with off-chip bulk component modulators. Here we demonstrate high-speed soliton microcomb actuation using integrated piezoelectric components13. By monolithically integrating AlN actuators14 on ultralow-loss Si3N4 photonic circuits15, we demonstrate voltage-controlled soliton initiation, tuning and stabilization with megahertz bandwidth. The AlN actuators use 300 nanowatts of power and feature bidirectional tuning, high linearity and low hysteresis. They exhibit a flat actuation response up to 1 megahertz-substantially exceeding bulk piezo tuning bandwidth-that is extendable to higher frequencies by overcoming coupling to acoustic contour modes of the chip. Via synchronous tuning of the laser and the microresonator, we exploit this ability to frequency-shift the optical comb spectrum (that is, to change the comb's carrier-envelope offset frequency) and make excursions beyond the soliton existence range. This enables a massively parallel frequency-modulated engine16,17 for lidar (light detection and ranging), with increased frequency excursion, lower power and elimination of channel distortions resulting from the soliton Raman self-frequency shift. Moreover, by modulating at a rate matching the frequency of high-overtone bulk acoustic resonances18, resonant build-up of bulk acoustic energy allows a 14-fold reduction of the required driving voltage, making it compatible with CMOS (complementary metal-oxide-semiconductor) electronics. Our approach endows soliton microcombs with integrated, ultralow-power and fast actuation, expanding the repertoire of technological applications of microcombs.

Microresonator-based solitons for massively parallel coherent optical communications.

Solitons are waveforms that preserve their shape while propagating, as a result of a balance of dispersion and nonlinearity. Soliton-based data transmission schemes were investigated in the 1980s and showed promise as a way of overcoming the limitations imposed by dispersion of optical fibres. However, these approaches were later abandoned in favour of wavelength-division multiplexing schemes, which are easier to implement and offer improved scalability to higher data rates. Here we show that solitons could make a comeback in optical communications, not as a competitor but as a key element of massively parallel wavelength-division multiplexing. Instead of encoding data on the soliton pulse train itself, we use continuous-wave tones of the associated frequency comb as carriers for communication. Dissipative Kerr solitons (DKSs) (solitons that rely on a double balance of parametric gain and cavity loss, as well as dispersion and nonlinearity) are generated as continuously circulating pulses in an integrated silicon nitride microresonator via four-photon interactions mediated by the Kerr nonlinearity, leading to low-noise, spectrally smooth, broadband optical frequency combs. We use two interleaved DKS frequency combs to transmit a data stream of more than 50 terabits per second on 179 individual optical carriers that span the entire telecommunication C and L bands (centred around infrared telecommunication wavelengths of 1.55 micrometres). We also demonstrate coherent detection of a wavelength-division multiplexing data stream by using a pair of DKS frequency combs-one as a multi-wavelength light source at the transmitter and the other as the corresponding local oscillator at the receiver. This approach exploits the scalability of microresonator-based DKS frequency comb sources for massively parallel optical communications at both the transmitter and the receiver. Our results demonstrate the potential of these sources to replace the arrays of continuous-wave lasers that are currently used in high-speed communications. In combination with advanced spatial multiplexing schemes and highly integrated silicon photonic circuits, DKS frequency combs could bring chip-scale petabit-per-second transceivers into reach.

Putting the Cart Before the Horse? Developing a Blended Anatomy Curriculum Supplemented by Cadaveric Anatomy.

Cadaveric anatomy is frequently described as the gold standard for anatomy education. Increasingly and especially following the COVID-19 pandemic, there is acceptance that a blended approach for anatomy curriculum delivery is optimal for learners.Setting up a new UK Medical School in 2019 necessitated building a new cadaveric anatomy facility. To enable anatomy curriculum delivery during the construction period (2019-2021), a technology-enhanced learning (TEL) anatomy curriculum was developed, as well as an anatomy laboratory suitable for TEL. Development of a TEL anatomy curriculum with the later inclusion of cadaveric anatomy is unusual since the typical model is to supplement cadaveric anatomy with TEL approaches.TEL solutions that provide digital visualisation of anatomy may support learners by reducing cognitive load. Examples include using colour and/or translucency features to highlight and signpost pertinent anatomy and constructing virtual anatomical models in real time, rather than dissection. Radiology and portable ultrasound provide clinically contextualised visualisations of anatomy; the latter offers a haptic learning experience too. A TEL anatomy laboratory can provide interactive learning experiences for engagement and outreach activities for young school children, where cadaveric anatomy is not suitable.

Turner Syndrome Mosaicism after Diagnosis of Coeliac Disease-A High Index of Clinical Suspicion Required?

The association of coeliac disease (CD) in girls with Turner syndrome (TS) is well described. There is, however, a paucity of current research describing TS in patients with known CD. We report two cases of mosaic Turner syndrome diagnosed in girls with CD who failed to achieve expected catch-up growth despite strict adherence to a gluten-free diet (GFD) and the normalisation of TGA-IgA levels. We highlight the need to consider additional diagnoses in patients with CD and ongoing faltering growth. In such patients, referral to a paediatric endocrinologist and relevant investigations, including genetic investigations, should be considered if growth remains suboptimal after one year with a GFD. First-line investigations should include thyroid function, IGF-1, cortisol, gonadotrophins, oestrogen/testosterone, prolactin, karyotype and a bone age X-ray. Clinical suspicion in this situation is key, as an early diagnosis of TS will allow timely treatment with growth hormone, inform discussion around ovarian function and allow screening for important TS associations.

A Legionella effector ADP-ribosyltransferase inactivates glutamate dehydrogenase.

ADP-ribosyltransferases (ARTs) are a widespread superfamily of enzymes frequently employed in pathogenic strategies of bacteria. Legionella pneumophila, the causative agent of a severe form of pneumonia known as Legionnaire's disease, has acquired over 330 translocated effectors that showcase remarkable biochemical and structural diversity. However, the ART effectors that influence L. pneumophila have not been well defined. Here, we took a bioinformatic approach to search the Legionella effector repertoire for additional divergent members of the ART superfamily and identified an ART domain in Legionella pneumophila gene0181, which we hereafter refer to as Legionella ADP-Ribosyltransferase 1 (Lart1) (Legionella ART 1). We show that L. pneumophila Lart1 targets a specific class of 120-kDa NAD+-dependent glutamate dehydrogenase (GDH) enzymes found in fungi and protists, including many natural hosts of Legionella. Lart1 targets a conserved arginine residue in the NAD+-binding pocket of GDH, thereby blocking oxidative deamination of glutamate. Therefore, Lart1 could be the first example of a Legionella effector which directly targets a host metabolic enzyme during infection.

Anchoring of a mental nerve stimulator for treatment of facial neuropathic pain: a case illustration.

INTRODUCTION: Mental nerve stimulation is recognised as a treatment option for neuropathic facial pain. Historically however, lead migration across the mobile temporomandibular joint has prevented this procedures utility. METHODS: We describe a new method of insertion and anchoring of a mental nerve stimulator for the management of refractory neuropathic pain in the distribution of the mental nerve. We anchored the stimulator lead to the mandibular body. RESULTS: Significant analgesic effect was achieved and no lead migration had occurred at 1 year post-operatively. CONCLUSIONS: This report describes in detail the procedure of mental nerve stimulator insertion, with a novel technique of mandibular anchoring of the lead.

Catalytic Asymmetric Additions of Enol Silanes to In Situ Generated Cyclic, Aliphatic N-Acyliminium Ions.

Strong and confined imidodiphosphorimidate (IDPi) catalysts enable highly enantioselective substitutions of cyclic, aliphatic hemiaminal ethers with enol silanes. 2-Substituted pyrrolidines, piperidines, and azepanes are obtained with high enantioselectivities, and the method displays a broad tolerance of various enol silane nucleophiles. Several natural products can be accessed using this methodology. Mechanistic studies support the intermediacy of non-stabilized, cyclic N-(exo-acyl)iminium ions, paired with the confined chiral counteranion. Computational studies suggest transition states that explain the observed enantioselectivity.

Direct and Catalytic C-Glycosylation of Arenes: Expeditious Synthesis of the Remdesivir Nucleoside.

Since early 2020, scientists have strived to find an effective solution to fight SARS-CoV-2, in particular by developing reliable vaccines that inhibit the spread of the disease and repurposing drugs for combatting its effects on the human body. The antiviral prodrug Remdesivir is still the most widely used therapeutic during the early stages of the infection. However, the current synthetic routes rely on the use of protecting groups, air-sensitive reagents, and cryogenic conditions, thus impeding a cost-efficient supply to patients. We have, therefore, focused on the development of a straightforward, direct addition of (hetero)arenes to unprotected sugars. Here we report a silylium-catalyzed and completely stereoselective C-glycosylation that initially yields the open-chain polyols, which can be selectively cyclized to provide either the kinetic α-furanose or the thermodynamically favored ß-anomer. The method significantly expedites the synthesis of Remdesivir precursor GS-441524 after a subsequent Mn-catalyzed C-H oxidation and deoxycyanation.

Expression of Free Fatty Acid Receptor 2 by Dendritic Cells Prevents Their Expression of Interleukin 27 and Is Required for Maintenance of Mucosal Barrier and Immune Response Against Colorectal Tumors in Mice.

BACKGROUND & AIMS: Intestinal microbes and their metabolites affect the development of colorectal cancer (CRC). Short-chain fatty acids are metabolites generated by intestinal microbes from dietary fiber. We investigated the mechanisms by which free fatty acid receptor 2 (FFAR2), a receptor for short-chain fatty acids that can affect the composition of the intestinal microbiome, contributes to the pathogenesis of CRC. METHODS: We performed studies with ApcMin/+ mice, ApcMin/+Ffar2-/- mice, mice with conditional disruption of Ffar2 in dendritic cells (DCs) (Ffar2fl/flCD11c-Cre mice), ApcMin/+Ffar2fl/flCD11c-Cre mice, and Ffar2fl/fl mice (controls); some mice were given dextran sodium sulfate to induce colitis, with or without a FFAR2 agonist or an antibody against interleukin 27 (IL27). Colon and tumor tissues were analyzed by histology, quantitative polymerase chain reaction, and 16S ribosomal RNA gene sequencing; lamina propria and mesenteric lymph node tissues were analyzed by RNA sequencing and flow cytometry. Intestinal permeability was measured after gavage with fluorescently labeled dextran. We collected data on colorectal tumors from The Cancer Genome Atlas. RESULTS: ApcMin/+Ffar2-/- mice developed significantly more spontaneous colon tumors than ApcMin/+ mice and had increased gut permeability before tumor development, associated with reduced expression of E-cadherin. Colon tumors from ApcMin/+Ffar2-/- mice had a higher number of bacteria than tumors from ApcMin/+ mice, as well as higher frequencies of CD39+CD8+ T cells and exhausted or dying T cells. DCs from ApcMin/+Ffar2-/- mice had an altered state of activation, increased death, and higher production of IL27. Administration of an antibody against IL27 reduced the numbers of colon tumors in ApcMin/+ mice with colitis. Frequencies of CD39+CD8+ T cells and IL27+ DCs were increased in colon lamina propria from Ffar2fl/flCD11c-Cre mice with colitis compared with control mice or mice without colitis. ApcMin/+Ffar2fl/flCD11c-Cre mice developed even more tumors than ApcMin/+Ffar2fl/fl mice, and their tumors had even higher numbers of IL27+ DCs. ApcMin/+ mice with colitis given the FFAR2 agonist developed fewer colon tumors, with fewer IL27+ DCs, than mice not given the agonist. DCs incubated with the FFAR2 agonist no longer had gene expression patterns associated with activation or IL27 production. CONCLUSIONS: Loss of FFAR2 promotes colon tumorigenesis in mice by reducing gut barrier integrity, increasing tumor bacterial load, promoting exhaustion of CD8+ T cells, and overactivating DCs, leading to their death. Antibodies against IL27 and an FFAR2 agonist reduce tumorigenesis in mice and might be developed for the treatment of CRC.

Metabolites Involved in Immune Evasion by Batrachochytrium dendrobatidis Include the Polyamine Spermidine.

Amphibians have been declining around the world for more than four decades. One recognized driver of these declines is the chytrid fungus Batrachochytrium dendrobatidis, which causes the disease chytridiomycosis. Amphibians have complex and varied immune defenses against B. dendrobatidis, but the fungus also has a number of counterdefenses. Previously, we identified two small molecules produced by the fungus that inhibit frog lymphocyte proliferation, methylthioadenosine (MTA) and kynurenine (KYN). Here, we report on the isolation and identification of the polyamine spermidine (SPD) as another significant immunomodulatory molecule produced by B. dendrobatidis SPD and its precursor, putrescine (PUT), are the major polyamines detected, and SPD is required for growth. The major pathway of biosynthesis is from ornithine through putrescine to spermidine. An alternative pathway from arginine to agmatine to putrescine appears to be absent. SPD is inhibitory at concentrations of ≥10 µM and is found at concentrations between 1 and 10 µM in active fungal supernatants. Although PUT is detected in the fungal supernatants, it is not inhibitory to lymphocytes even at concentrations as high as 100 µM. Two other related polyamines, norspermidine (NSP) and spermine (SPM), also inhibit amphibian lymphocyte proliferation, but a third polyamine, cadaverine (CAD), does not. A suboptimal (noninhibitory) concentration of MTA (10 µM), a by-product of spermidine synthesis, enhances the inhibition of SPD at 1 and 10 µM. We interpret these results to suggest that B. dendrobatidis produces an "armamentarium" of small molecules that, alone or in concert, may help it to evade clearance by the amphibian immune system.

Community-acquired acute meningitis and encephalitis: a narrative review.

Meningitis and encephalitis are medical emergencies. Patients need prompt evaluation and immediate empiric therapy to reduce the likelihood of fatal outcomes and chronic neurological sequelae. Conjugate bacterial vaccines have significantly reduced the incidence of bacterial meningitis, especially in children. As the results of changes in patterns of bacterial drug sensitivity, ceftriaxone is now part of the recommended empiric treatment for bacterial meningitis and should be administered as early as possible. Neuroimaging delays the treatment of meningitis and is not needed in most cases. Adjunctive corticosteroid therapy is of benefit for many patients with meningitis and should be initiated in most adults before antibiotic therapy. Molecular testing can assist the specific diagnosis of encephalitis and should be based on the exposure history and geographic risk factors relevant to the patient, but non-infectious causes of encephalitis are also common. Empiric therapy for encephalitis should be directed at the most frequently identified infectious pathogen, herpes simplex virus type 1 (ie, intravenous aciclovir). Vaccines can protect against the major pathogens of childhood infections (measles, mumps, rubella, polio, varicella viruses), influenza viruses, and exotic pathogens that cause meningitis and encephalitis (rabies, Japanese encephalitis, dengue, yellow fever, tick-borne encephalitis viruses, Mycobacterium tuberculosis).

Physiochemical Characteristics of Calcium Hydroxylapatite (CaHA).

The clinical performance of fillers in soft tissue augmentation depends upon their physiochemical properties, anatomical areas injected, interaction with the recipient, and the skill and experience of the physician. Scientific measures of filler properties facilitate appropriate selection of treatments for optimal treatment outcomes, and inform adjustments to treatments that improve patient safety and aesthetic outcomes. The rheological properties of calcium hydroxylapatite (CaHA), elastic modulus (G') and viscosity, coupled with its capacity to offer both immediate results and continued stimulation of collagen type I deposition, support its distinction as an ideal treatment for the volume loss characteristic of aging. Furthermore, the comparatively higher G' of CaHA offers a physiochemical basis for the clinical performance observed by the authors, especially in regions such as the temple and chin, where the force exerted by CaHA against bone permits expansion of overlaying tissue, permitting it to behave as a liquid implant.

Physiochemical Characteristics of Poly-L-Lactic Acid (PLLA).

Poly-L-lactic acid (PLLA) is a synthetic, biocompatible, biodegradable polymer. For soft-tissue augmentation, the size and chemical attributes of the PLLA microparticles are central to this agent's ability to promote a subclinical inflammatory response that stimulates deposition of collagen in the extracellular matrix. The resultant restoration of facial volume occurs in a controlled, predictable manner and is long lasting. The unique physiochemical and biostimulatory properties of PLLA differentiate it from other available treatments and are the foundation of the unique treatment methodology required for optimal results.

Calcium Hydroxyapatite (CaHA) Indication for Hand Rejuvenation.

The recent approval in 2015 of Radiesse for injection into the hand by the FDA has spurred an increase in interest among patients and clinicians in nonsurgical hand rejuvenation using fillers. Application of the same techniques used to treat the face to the dorsum of the hands does not account for the unique nature of the skin and underlying anatomy, and can lead to suboptimal outcomes and an increased risk of adverse events such as the formation of nodules. Here, the authors discuss dilution strategies and injection techniques for hand rejuvenation using Radiesse for optimal patient safety and aesthetic outcomes.

Expanding Treatment Options for Injectable Agents.

Loss of facial volume and soft-tissue support are common to types of facial aging. Restoration of a youthful appearance relies upon correction of this loss, and can be achieved in various capacities through use of biostimulatory or hyaluronic acids (HA) injectable fillers. Here, the authors discuss the versatility of calcium hydroxylapatite (CaHA) in volume replacement and the applications and facial regions for which CaHA, poly-L-lactic acid (PLLA), and HA fillers are best suited.

Composite Facial Volumization With Calcium Hydroxylapatite (CaHA) for the Treatment of Aging.

Paradigms in the treatment of aging have evolved to address volume loss as a central and primary hallmark of the aging face. The concept of "composite volumization" was recently proposed by Dr. Z. Paul Lorenc to describe the effect of Radiesse (Merz Aesthetics, Inc., Raleigh, NC), when placed on bone in the supraperiosteal plane, on all overlying tissues (skin, superficial and deep fat compartments, and muscle). The physiochemical properties of Radiesse make it especially well suited for efficient and effective volumization of areas especially prone to volume loss; the temple, zygomatic arch, anterior cheek, pyriform aperture, and prejowl sulcus. Placement of Radiesse on bone in these areas creates a scaffold upon which additional restoration of fine lines and wrinkles may be accomplished, restoring a youthful appearance.

Differentiating Nonpermanent Injectable Fillers: Prevention and Treatment of Filler Complications.

Though the incidence of complications and adverse events with dermatological fillers is inherently low, practitioners should be well versed in both prevention of filler complications and the treatment algorithms for addressing "granulomas," nodules, infection, and vascular compromise. Appropriate preventative measures, coupled with timely and effective treatment, are critically important for patient safety and satisfaction. In addition to the preventive measures and treatment algorithms outlined here, the authors emphasize that the broad classification and treatment of nodules as "granulomas" is likely to lead to ineffective treatment, or worse, unnecessary exposure to incorrect treatment. In practice, nodules are classified and treated based on clinical manifestation (eg, late vs early or noninflammatory vs inflammatory) rather than on histology. Indeed, classification of a nodule as a granuloma requires a histological examination, rarely available (or necessary) in clinical practice to guide treatment. Thus, the apparent inflammatory nature of the nodule and the time of onset should drive treatment approach. The treatment algorithms presented here are based on these clinically meaningful parameters.

An Interrupted Pummerer/Nickel-Catalysed Cross-Coupling Sequence.

An interrupted Pummerer/nickel-catalysed cross-coupling strategy has been developed and used in the elaboration of styrenes. The operationally simple method can be carried out as a one-pot process, involves the direct formation of stable alkenyl sulfonium salt intermediates, utilises a commercially available sulfoxide, catalyst, and ligand, operates at ambient temperature, accommodates sp-, sp2 -, and sp3 -hybridised organozinc coupling partners, and delivers functionalised styrene products in high yields over two steps. An interrupted Pummerer/cyclisation approach has also been used to access carbo- and heterocyclic alkenyl sulfonium salts for cross-coupling.