On the mechanism of carboxylate elimination from carbohydrate monoester-derived radicals

A computational study of the mechanism of hydrogen atom transfer-induced carboxylate elimination from monoacylated 1,2-diol groups in pyranosides is presented. A comprehensive analysis of the 1,2-migration, elimination and fragmentation pathways reveals that concerted elimination via a 7-membered, hydrogen-bonded transition state is favored. Relative rates of elimination inferred from an intramolecular competition experiment are consistent with the trends obtained from the calculations.

Axonal excitability as an early biomarker of nerve involvement in hereditary transthyretin amyloidosis

OBJECTIVES

The treatment of hereditary transthyretin amyloidosis polyneuropathy (ATTRv-PN) has been revolutionised by genetic therapies, with dramatic improvements in patient outcomes. Whilst the optimal timing of treatment initiation remains unknown, early treatment is desirable. Consequently, the aim of the study was to develop biomarkers of early nerve dysfunction in ATTRv-PN.

METHODS

Ulnar motor and sensory axonal excitability studies were prospectively undertaken on 22 patients with pathogenic hereditary transthyretin amyloid (ATTRv) gene variants, 12 with large fibre neuropathy (LF+) and 10 without (LF-), with results compared to age- and sex-matched healthy controls.

RESULTS

In motor axons we identified a continuum of change from healthy controls, to LF- and LF+ ATTRv with progressive reduction in hyperpolarising threshold electrotonus (TEh40(10-20 ms): p = 0.04, TEh40(20-40 ms): p = 0.01 and TEh40(90-10 ms): p = 0.01), suggestive of membrane depolarisation. In sensory axons lower levels of subexcitability were observed on single (SubEx) and double pulse (SubEx2) recovery cycle testing in LF+ (SubEx: p = 0.015, SubEx2: p = 0.015, RC(2-1): p = 0.04) suggesting reduced nodal slow potassium conductance, which promotes sensory hyperexcitability, paraesthesia and pain. There were no differences in sensory or motor excitability parameters when comparing different ATTRv variants.

CONCLUSIONS

These progressive changes seen across the disease spectrum in ATTRv-PN suggest that axonal excitability has utility to identify early and progressive nerve dysfunction in ATTRv, regardless of genotype.

SIGNIFICANCE

Axonal excitability is a promising early biomarker of nerve dysfunction in ATTRv-PN.

Boronic Acid-Catalyzed Regio- and Stereoselective N-Glycosylations of Purines and Other Azole Heterocycles: Access to Nucleoside Analogues

In the presence of an arylboronic acid catalyst, azole-type heterocycles, including purines, tetrazoles, triazoles, indazoles, and benzo-fused congeners, undergo regio- and stereoselective N-glycosylations with furanosyl and pyranosyl trichloroacetimidate donors. The protocol, which does not require stoichiometric activators, specialized leaving groups, or drying agents, provides access to nucleoside analogues and enables late-stage N-glycosylation of azole-containing pharmaceutical agents. A mechanism involving simultaneous activation of the glycosyl donor and acceptor by the organoboron catalyst has been proposed, supported by kinetic analysis and computational modeling.

Transformations of carbohydrate derivatives enabled by photocatalysis and visible light photochemistry

This review article highlights the diverse ways in which recent developments in the areas of photocatalysis and visible light photochemistry are impacting synthetic carbohydrate chemistry. The major topics covered are photocatalytic glycosylations, generation of radicals at the anomeric position, transformations involving radical formation at non-anomeric positions, additions to glycals, processes initiated by photocatalytic hydrogen atom transfer from sugars, and functional group interconversions at OH and SH groups. Factors influencing stereo- and site-selectivity in these processes, along with mechanistic aspects, are discussed.

Organoboron/Palladium Cocatalytic Allylation of NH-Sulfoximines Using Allylic Alcohols

Synergistic organoboron/palladium cocatalysis enables dehydrative couplings of NH-sulfoximines with allylic alcohols, furnishing the corresponding N-allylated products. The reactions proceed in the absence of a Brønsted base and are tolerant of diverse sulfoximine partners, including functionalized variants. Experimental and computational studies suggest that the sulfoximine reagent is activated by complexation to the boronic acid cocatalyst.

Patisiran Treatment in Patients with Transthyretin Cardiac Amyloidosis

BACKGROUND

Transthyretin amyloidosis, also called ATTR amyloidosis, is associated with accumulation of ATTR amyloid deposits in the heart and commonly manifests as progressive cardiomyopathy. Patisiran, an RNA interference therapeutic agent, inhibits the production of hepatic transthyretin.

METHODS

In this phase 3, double-blind, randomized trial, we assigned patients with hereditary, also known as variant, or wild-type ATTR cardiac amyloidosis, in a 1:1 ratio, to receive patisiran (0.3 mg per kilogram of body weight) or placebo once every 3 weeks for 12 months. A hierarchical procedure was used to test the primary and three secondary end points. The primary end point was the change from baseline in the distance covered on the 6-minute walk test at 12 months. The first secondary end point was the change from baseline to month 12 in the Kansas City Cardiomyopathy Questionnaire-Overall Summary (KCCQ-OS) score (with higher scores indicating better health status). The second secondary end point was a composite of death from any cause, cardiovascular events, and change from baseline in the 6-minute walk test distance over 12 months. The third secondary end point was a composite of death from any cause, hospitalizations for any cause, and urgent heart failure visits over 12 months.

RESULTS

A total of 360 patients were randomly assigned to receive patisiran (181 patients) or placebo (179 patients). At month 12, the decline in the 6-minute walk distance was lower in the patisiran group than in the placebo group (Hodges-Lehmann estimate of median difference, 14.69 m; 95% confidence interval [CI], 0.69 to 28.69; P = 0.02); the KCCQ-OS score increased in the patisiran group and declined in the placebo group (least-squares mean difference, 3.7 points; 95% CI, 0.2 to 7.2; P = 0.04). Significant benefits were not observed for the second secondary end point. Infusion-related reactions, arthralgia, and muscle spasms occurred more often among patients in the patisiran group than among those in the placebo group.

CONCLUSIONS

In this trial, administration of patisiran over a period of 12 months resulted in preserved functional capacity in patients with ATTR cardiac amyloidosis. (Funded by Alnylam Pharmaceuticals; APOLLO-B ClinicalTrials.gov number, NCT03997383.).

Use of adrenaline to manage suspected anaphylaxis following COVID-19 vaccination: An Australian retrospective cohort study

BACKGROUND

The rate of anaphylaxis following COVID-19 vaccinations is estimated to be 2-11 cases per million doses administered. However, adrenaline is occasionally used in individuals who are later diagnosed with immunisation stress-related responses, as their initial presenting signs and symptoms can appear similar to that of anaphylaxis. This study aims to describe the clinical profile of individuals who had received adrenaline following a COVID-19 vaccine and their subsequent revaccination outcomes.

METHODS

We examined notifications of cases who had received adrenaline following a COVID-19 vaccine in New South Wales, Australia. The cases were classified into Brighton Collaboration Case Definition (BCCD) for anaphylaxis, their clinical presentation, management and subsequent revaccination outcomes were compared.

RESULTS

From 22 February 2021 to 30 September 2021, there were 222 cases where adrenaline was administered. Of these, 32 (14 %) fulfilled Level 1 BCCD, 59 (27%) Level 2, 2 (1%) Level 3, 97 (44%) Level 4 and 32 (14 %) Level 5. The most commonly reported symptoms were sensation of throat closure (n = 116, 52%), difficulty breathing (n = 82, 37%) and nausea (n = 55, 25 %). Of the 176 (79%) individuals who proceeded to further vaccination, 89 (51%) received the same vaccine formulation and only 14 (8%) experienced another allergic adverse event with 9 (5%) receiving adrenaline.

CONCLUSION

Less than one in five individuals who received adrenaline met Level 1 BCCD criteria for anaphylaxis. Many reactions that were treated with adrenaline had little to no diagnostic certainty of anaphylaxis and in such cases repeat vaccination had a high likelihood of being tolerated. Increased awareness and education on objective signs and symptoms of anaphylaxis is required to ensure appropriate use of adrenaline.

Cardiac "hypertrophy" phenotyping: differentiating aetiologies with increased left ventricular wall thickness on echocardiography

Aims

Differentiating phenotypes of cardiac "hypertrophy" characterised by increased wall thickness on echocardiography is essential for management and prognostication. Transthoracic echocardiography is the most commonly used screening test for this purpose. We sought to identify echocardiographic markers that distinguish infiltrative and storage disorders that present with increased left ventricular (LV) wall thickness, namely, cardiac amyloidosis (CA) and Anderson-Fabry disease (AFD), from hypertensive heart disease (HHT).

Methods

Patients were retrospectively recruited from Westmead Hospital, Sydney, and Princess Alexandra Hospital, Brisbane. LV structural, systolic, and diastolic function parameters, as well as global (LVGLS) and segmental longitudinal strains, were assessed. Previously reported echocardiographic parameters including relative apical sparing ratio (RAS), LV ejection fraction-to-strain ratio (EFSR), mass-to-strain ratio (MSR) and amyloidosis index (AMYLI) score (relative wall thickness × E/e') were evaluated.

Results

A total of 209 patients {120 CA [58 transthyretin amyloidosis (ATTR) and 62 light-chain (AL) amyloidosis], 31 AFD and 58 HHT patients; mean age 64.1 ± 13.7 years, 75% male} comprised the study cohort. Echocardiographic measurements differed across the three groups, The LV mass index was higher in both CA {median 126.6 [interquartile range (IQR) 106.4-157.9 g/m²]} and AFD [median 134 (IQR 108.8-152.2 g/m²)] vs. HHT [median 92.7 (IQR 79.6-102.3 g/m²), p < 0.05]. LVGLS was lowest in CA [median 12.29 (IQR 10.33-15.56%)] followed by AFD [median 16.92 (IQR 14.14-18.78%)] then HHT [median 18.56 (IQR 17.51-19.97%), p < 0.05]. Diastolic function measurements including average e' and E/e' were most impaired in CA and least impaired in AFD. Indexed left atrial volume was highest in CA. EFSR and MSR differentiated secondary (CA + AFD) from HHT [receiver operating curve-area under the curve (ROC-AUC) of 0.80 and 0.91, respectively]. RAS and AMYLI score differentiated CA from AFD (ROC-AUC of 0.79 and 0.80, respectively). A linear discriminant analysis with stepwise variable selection using linear combinations of LV mass index, average e', LVGLS and basal strain correctly classified 79% of all cases.

Conclusion

Simple echocardiographic parameters differentiate between different "hypertrophic" cardiac phenotypes. These have potential utility as a screening tool to guide further confirmatory testing.

Understanding the Origins of Site Selectivity in Hydrogen Atom Transfer Reactions from Carbohydrates to the Quinuclidinium Radical Cation: A Computational Study

The use of quinuclidine as a hydrogen atom transfer (HAT) mediator, along with a light-absorbing photoredox catalyst, has proved to be a powerful and general approach for achieving site-selective radical formation from carbohydrate substrates. Despite numerous literature reports documenting the scope and limitations of such processes, a general rationale for the origins of site selectivity in the key HAT step has not been advanced. In this study, density functional theory calculations (M06-2X/def2-TZVP/PCM(acetonitrile)) were used to model transition states for HAT to the quinuclidinium radical cation from pyranosides and furanosides having various configurations and substitution patterns. The data set (>120 transition state geometries and energies) has allowed for a detailed examination of the factors that influence the relative rates, augmented by additional analysis using the atoms in molecules (AIM) and distortion/interaction-activation strain frameworks. The trends that have emerged regarding the effects of configuration, conformation, substitution, and noncovalent interactions are consistent with experimental observations and reveal a key role for C-H···O hydrogen bonds in stabilizing transition states for HAT to the quinuclidinium radical cation.

Mechanistic Study of the Copper(II)-Mediated Site-Selective O-Arylation of Glycosides with Arylboronic Acids

Glycosides having multiple free OH groups have been shown to undergo site-selective O-arylations in the presence of arylboronic acids and copper(II) acetate. Herein, a mechanistic analysis of these Chan-Evans-Lam-type couplings is presented based on reaction kinetics, mass spectrometric analysis of reaction mixtures, and substituent effect studies. The results establish that the formation of a substrate-derived boronic ester accelerates the rate-determining transmetalation step. Intramolecular transfer of the aryl group from the boronic ester is ruled out in favor of a pathway in which the key pre-transmetalation assembly is generated from a boronic ester, a copper complex, and a second equivalent of arylboronic acid.

Efficacy and safety of vutrisiran for patients with hereditary transthyretin-mediated amyloidosis with polyneuropathy: a randomized clinical trial

BACKGROUND

The study objective was to assess the effect of vutrisiran, an RNA interference therapeutic that reduces transthyretin (TTR) production, in patients with hereditary transthyretin (ATTRv) amyloidosis with polyneuropathy.

METHODS

HELIOS-A was a phase 3, global, open-label study comparing the efficacy and safety of vutrisiran with an external placebo group (APOLLO study). Patients were randomized 3:1 to subcutaneous vutrisiran 25 mg every 3 months (Q3M) or intravenous patisiran 0.3 mg/kg every 3 weeks (Q3W) for 18 months.

RESULTS

HELIOS-A enrolled 164 patients (vutrisiran, n = 122; patisiran reference group, n = 42); external placebo, n = 77. Vutrisiran met the primary endpoint of change from baseline in modified Neuropathy Impairment Score +7 (mNIS+7) at 9 months (p = 3.54 × 10^-12), and all secondary efficacy endpoints; significant improvements versus external placebo were observed in Norfolk Quality of Life-Diabetic Neuropathy, 10-meter walk test (both at 9 and 18 months), mNIS+7, modified body-mass index, and Rasch-built Overall Disability Scale (all at 18 months). TTR reduction with vutrisiran Q3M was non-inferior to within-study patisiran Q3W. Most adverse events were mild or moderate in severity, and consistent with ATTRv amyloidosis natural history. There were no drug-related discontinuations or deaths.

CONCLUSIONS

Vutrisiran significantly improved multiple disease-relevant outcomes for ATTRv amyloidosis versus external placebo, with an acceptable safety profile.

CLINICALTRIALS.GOV

NCT03759379.

Synthesis of 1,2,4,5-oxadiazaboroles by three-component condensations of hydroxylamines, nitriles, and diarylborinic acids

A method for the synthesis of substituted 1,2,4,5-oxadiazaboroles is described, in which hydroxylamines, nitriles, and diarylborinic acids engage in a three-component condensation reaction. The protocol provides access to a substitution pattern that is not readily available through other methods—namely, 2,3-disubstitution, with a tetracoordinate boron center. Structures of representative members of this class of heterocycles were determined by single crystal X-ray diffraction analysis.

Algorithm for biological second messenger analysis with dynamic regions of interest

Physiological function is regulated through cellular communication that is facilitated by multiple signaling molecules such as second messengers. Analysis of signal dynamics obtained from cell and tissue imaging is difficult because of intricate spatially and temporally distinct signals. Signal analysis tools based on static region of interest analysis may under- or overestimate signals in relation to region of interest size and location. Therefore, we developed an algorithm for biological signal detection and analysis based on dynamic regions of interest, where time-dependent polygonal regions of interest are automatically assigned to the changing perimeter of detected and segmented signals. This approach allows signal profiles to be rigorously and precisely tracked over time, eliminating the signal distortion observed with static methods. Integration of our approach with state-of-the-art image processing and particle tracking pipelines enabled the isolation of dynamic cellular signaling events and characterization of biological signaling patterns with distinct combinations of parameters including amplitude, duration, and spatial spread. Our algorithm was validated using synthetically generated datasets and compared with other available methods. Application of the algorithm to volumetric time-lapse hyperspectral images of cyclic adenosine monophosphate measurements in rat microvascular endothelial cells revealed distinct signal heterogeneity with respect to cell depth, confirming the utility of our approach for analysis of 5-dimensional data. In human tibial arteries, our approach allowed the identification of distinct calcium signal patterns associated with atherosclerosis. Our algorithm for automated detection and analysis of second messenger signals enables the decoding of signaling patterns in diverse tissues and identification of pathologic cellular responses.

Combined hyperspectral imaging, monolayer stress microscopy, and S8 image analysis approaches for simultaneously interrogating cellular signals and biomechanics

Second messenger signals, e.g., Ca2+ and cyclic nucleotides, orchestrate a wide range of cellular events. The methods by which second messenger signals determine specific physiological responses are complex. Recent studies point to the importance of temporal and spatial encoding in determining signal specificity. Studies also indicate the importance of mechanical stimuli, substrate stiffness, and mechanical responses - the "mechanosome" - in regulating physiology. Hence, approaches that probe both chemical and mechanical signals are needed. Here, we report preliminary efforts to combine hyperspectral imaging for second messenger signal measurements, monolayer stress microscopy for mechanical force measurements, and S8 analysis software for quantifying localized signals - specifically, Ca2+ dynamics and mechanical forces in human airway smooth muscle cells (HASMCs). HASMCs were prepared as confluent monolayers on 11 kPa gels with embedded fluorescent microparticles that serve as fiducial markers as well as smaller microparticles to measure deformation (strain). Imaging was performed using a custom excitation-scanning hyperspectral microscope. Hyperspectral images were unmixed to identify signals from cellular fluorescent labels (e.g., CAL 590-AM) and fluorescent microparticles. Images were analyzed to quantify localized force dynamics through monolayer stress microscopy. S8 software was used to identify, track, and quantify spatially-localized Ca2+ activity. Results indicate that localized and transient cellular signals and forces can be quantified and mapped within cell populations. Importantly, these results establish a method for simultaneous interrogation of cellular signals and mechanical forces that may play synergistic roles in regulating downstream cellular physiology in confluent monolayers. This work was supported by NIH P01HL066299, R01HL137030, R01HL058506, and NSF MRI1725937. Drs. Leavesley and Rich disclose financial interest in a university start-up company, SpectraCyte LLC, to commercialize spectral imaging technologies.

Current approaches to the diagnosis and management of amyloidosis

Amyloidosis is a collection of diseases caused by the misfolding of proteins that aggregate into insoluble amyloid fibrils and deposit in tissues. While these fibrils may aggregate to form insignificant localised deposits, they can also accumulate in multiple organs to the extent that amyloidosis can be an immediately life-threatening disease, requiring urgent treatment. Recent advances in diagnostic techniques and therapies are dramatically changing the disease landscape and patient prognosis. Delays in diagnosis and treatment remain the greatest challenge, necessitating physician awareness of the common clinical presentations that suggest amyloidosis. The most common types are transthyretin (ATTR) amyloidosis followed by immunoglobulin light-chain (AL) amyloidosis. While systemic AL amyloidosis was previously considered a death sentence with no effective therapies, significant improvement in patient survival has occurred over the past 2 decades, driven by greater understanding of the disease process, risk-adapted adoption of myeloma therapies such as proteosome inhibitors (bortezomib) and monoclonal antibodies (daratumumab) and improved supportive care. ATTR amyloidosis is an underdiagnosed cause of heart failure. Technetium scintigraphy has made noninvasive diagnosis much easier, and ATTR is now recognised as the most common type of amyloidosis because of the increased identification of age-related ATTR. There are emerging ATTR treatments that slow disease progression, decrease patient hospitalisations and improve patient quality of life and survival. This review aims to update physicians on recent developments in amyloidosis diagnosis and management and to provide a diagnostic and treatment framework to improve the management of patients with all forms of amyloidosis.

Synergistic Organoboron/Palladium Catalysis for Regioselective N-Allylations of Azoles with Allylic Alcohols

A method for regioselective palladium-catalyzed allylic alkylation of ambident nitrogen heterocycles, employing simple allylic alcohols as electrophile precursors, is described. An organoboron co-catalyst serves both to activate the azole-type nucleophile toward selective N-functionalization and to accelerate the formation of a π-allylpalladium complex from the allylic alcohol. The method can be applied to various heterocycle types, including 1,2,3- and 1,2,4-triazoles, tetrazoles, pyrazoles, and purines, and can be extended to substituted allylic alcohol partners.

Catalyst-Controlled, Site-Selective Sulfamoylation of Carbohydrate Derivatives

Methods for site-selective sulfamoylation of secondary hydroxyl groups in pyranosides are described. Using a boronic acid catalyst, selective installation of a Boc-protected sulfamoyl group at the equatorial position of cis-diols in manno- and galacto-configured substrates has been achieved. Activation of trans-diol groups in gluco- and galacto-configured substrates is also possible by employing an organotin catalyst.

Alterations in multi-layer strain in AL amyloidosis

BACKGROUND

Cardiac involvement in AL amyloidosis portends a poor prognosis. 2D-speckle tracking echocardiography (2D-STE) strain can identify subclinical cardiac involvement. This study performed multilayer and multiplanar 2D-STE myocardial strain analysis.

METHODS

We compared 75 AL amyloidosis patients to 49 hypertensive patients and 49 healthy controls. Longitudinal strain was obtained from epicardial, mid-myocardial and endocardial layers; segmental strain was measured from mid-myocardial basal, mid and apical segments.

RESULTS

Global longitudinal strain was reduced in epicardial (-14.3 ± -4.0% vs. -17.4 ± 2.2% vs. -17.5 ± -2.0%, p < .001), mid-myocardial (-16.3 ± -4.5% vs. -19.7 ± 2.5% vs. -19.7 ± -2.2%, p < .001) and endocardial layers (-18.7 ± -4.9% vs. -22.2 ± 3.0% vs. -22.3 ± -2.6%, p < .001) in amyloid patients compared to hypertensive and healthy controls. Segmental strain confirmed significant reduction in basal (-11.2 ± -3.9% vs. -17.6 ± 2.7% vs. -20.9 ± -3.4%, p < .001) and mid (-14.8 ± -4.3% vs. -19.2 ± 2.5% vs. -19.6 ± -2.2%, p < .001) LV segments in the AL amyloid group. Receiver operating curve analysis demonstrated that an optimal cut-off of -16% for basal segmental strain better differentiated AL amyloid from hypertensive group (sensitivity 96%, specificity 70%, AUC 0.93), compared to relative apical sparing (AUC of 0.85).

CONCLUSION

Strain demonstrated myocardial involvement in all layers in AL amyloidosis, with reduced basal segmental longitudinal strain a likely marker of early disease.

Borinic Acid Catalyzed Regioselective N-Alkylation of Azoles

A method for regioselective N-alkylation of ambident, azole-type heterocycles with alkene or epoxide electrophiles is described. In the presence of diphenylborinic acid (Ph₂BOH) and an amine cocatalyst, heterocyclic nucleophiles such as 1,2,3- and 1,2,4-triazoles, substituted tetrazoles, and purine are activated toward selective N-functionalization. The scope of electrophilic partners includes enones, 2-vinylpyridine, phenyl vinyl sulfone, a dehydroalanine derivative, and epoxides. Mechanistic studies, including in situ ¹¹B NMR spectroscopy and kinetic analysis, are discussed.

Restricted Intimal Ca2+ Signaling Associated With Cardiovascular Disease

Endothelial dysfunction is a key feature of cardiovascular disease (CVD) including atherosclerosis. Impaired endothelial signaling leads to plaque formation, vascular wall remodeling and widespread cardiovascular dysregulation. The specific changes along the vascular intima associated with atherosclerosis, including the vulnerable circulation downstream of the flow obstruction, remain poorly understood. Previous findings from animal models suggest that preservation of a distinct Ca2+ signaling profile along the arterial endothelial network is crucial for maintaining vasculature homeostasis and preventing arterial disease. Ca2+ signaling in the intact human artery intima has not been well characterized. Here, we employed confocal imaging and a custom analysis algorithm to assess the spatially and temporally dynamic Ca2+ signaling profiles of human peripheral arteries isolated from the amputated legs of patients with advanced CVD (peripheral artery disease and/or diabetes) or patients who had lost limbs due to non-cardiovascular trauma. In all tibial artery branches (0.5-5 mm diameter) assessed, the intima consistently elicited a broad range of basal Ca2+ signals ranging from isolated focal transients to broad waves. Arteries from patients with existing CVD displayed a restricted intimal Ca2+ signaling pattern characterized by diminished event amplitude and area. Stimulation of type-4 vanilloid transient receptor potential channels (TRPV4) amplified endothelial Ca2+ signals; however, these signals remained smaller and spatially confined in arteries from patients with CVD verses those without CVD. Our findings reveal a characteristic underlying basal Ca2+ signaling pattern within the intima of human peripheral arteries and suggest a distinct truncation of the inherent Ca2+ profile with CVD.

Effects of Configuration and Substitution on C-H Bond Dissociation Enthalpies in Carbohydrate Derivatives: A Systematic Computational Study

Density functional theory was used to calculate C-H bond dissociation enthalpies (BDEs) at each position of a diverse collection of pyranosides and furanosides differing in relative configuration and substitution patterns. A detailed analysis of the resulting data set (186 BDEs, calculated at the M06-2X/def2-TZVP level of theory) highlights the ways in which stereoelectronic effects, conformational properties, and noncovalent interactions can influence the strengths of C-H bonds in carbohydrates. The results point toward opportunities to alter the radical reactivity of carbohydrate derivatives by variation of their stereochemical configuration or the positions and types of protective groups.

Photocatalytic, site-selective oxidations of carbohydrates

Site-selective oxidations of carbohydrates, employing acridinium photocatalysis and quinuclidine hydrogen atom transfer catalysis, are presented. Protocols have been developed for oxidations of all-equatorial carbohydrates as well as those containing cis-1,2-diols. Site-selectivity reflects the relative rates of hydrogen atom transfer from the carbohydrate C-H bonds, and can be enhanced using a phosphate hydrogen-bonding or boronic acid catalyst.

Correlation Between Quantitative Uptake of 99mTC-DPD and Echocardiographic Parameters in Cardiac ATTR: A Novel Follow-Up Strategy

Aims: There has been a paradigm shift in diagnosis of cardiac transthyretin amyloidosis (ATTR) with non-invasive techniques including technetium-99m 3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) bone scintigraphy. We evaluated structural and functional biventricular alterations by transthoracic echocardiography (TTE) and determined the correlation with 99mTc-DPD tracer uptake in ATTR. Materials and Methods: ATTR patients (wild-type, hereditary or asymptomatic transthyretin [TTR] variant carriers) with 99mTc-DPD and TTE were selected; 99mTc-DPD uptake was analyzed quantitatively. TTE assessment of left ventricle (LV) and right ventricle (RV) parameters was performed. Results: Forty ATTR patients (wild-type n = 17; hereditary ATTR and TTR variant carriers n = 23; median age 68.8 ± 22 years) were included. TTE parameters displaying good correlation with 99mTc-DPD tracer uptake included LV average wall thickness (r = 0.837), LV indexed mass (LVMI; r = 0.802), RV wall thickness (r = 0.610), average e' (r = -0.830), E/e' ratio (r = 0.786), LV global longitudinal strain (GLS; r = 0.714) and RV GLS (r = 0.632; p < 0.001 for all). Hereditary ATTR and TTR variant carriers without cardiac tracer uptake had normal echocardiographic parameters. Receiver operating characteristic curves demonstrated strong diagnostic accuracies for structural (LV wall thickness, LVMI and RV wall thickness; area under the curve (AUC) of 0.96 for all) and functional (LV and RV GLS; AUC of 0.86 and 0.88, respectively) parameters. Conclusion: Good correlations between TTE biventricular structural and functional parameters were demonstrated with quantitative 99mTc-DPD uptake. Echocardiography may potentially assume a significant role in longitudinal follow-up for monitoring disease progression and for evaluating treatment response.

Diarylborinic Acid-Catalyzed Regioselective Ring Openings of Epoxy Alcohols with Pyrazoles, Imidazoles, Triazoles, and Other Nitrogen Heterocycles

A method for regioselective ring openings of 3,4- and 2,3-epoxy alcohols with ambident nitrogen heterocycles is described. Using a diarylborinic acid catalyst, a single regioisomer is favored in couplings of nucleophile and electrophile partners that display low regioselectivity under conventional conditions. The method provides access to aromatic heterocycles bearing stereochemically defined, functionalized alkyl substituents, a product class similar in structure to medicinally relevant compounds such as the acyclic nucleoside analogues.

Site- and Stereoselective C-H Alkylations of Carbohydrates Enabled by Cooperative Photoredox, Hydrogen Atom Transfer, and Organotin Catalysis

Diorganotin dihalides act as cocatalysts for site-selective and stereoselective couplings of diol-containing carbohydrates with electron-deficient alkenes in the presence of an Ir(III) photoredox catalyst and quinuclidine, a hydrogen atom transfer mediator. Quantum-chemical calculations support a proposed mechanism involving the formation of a cyclic stannylene acetal intermediate that shows enhanced reactivity toward hydrogen atom abstraction by the quinuclidinium radical cation. Addition of the carbon-centered radical to the alkene partner results in C-alkylation of the carbohydrate substrate.

Epidemiology of Traumatic Brain Injury in Europe: A Living Systematic Review

This systematic review provides a comprehensive, up-to-date summary of traumatic brain injury (TBI) epidemiology in Europe, describing incidence, mortality, age, and sex distribution, plus severity, mechanism of injury, and time trends. PubMed, CINAHL, EMBASE, and Web of Science were searched in January 2015 for observational, descriptive, English language studies reporting incidence, mortality, or case fatality of TBI in Europe. There were no limitations according to date, age, or TBI severity. Methodological quality was assessed using the Methodological Evaluation of Observational Research checklist. Data were presented narratively. Sixty-six studies were included in the review. Country-level data were provided in 22 studies, regional population or treatment center catchment area data were reported by 44 studies. Crude incidence rates varied widely. For all ages and TBI severities, crude incidence rates ranged from 47.3 per 100,000, to 694 per 100,000 population per year (country-level studies) and 83.3 per 100,000, to 849 per 100,000 population per year (regional-level studies). Crude mortality rates ranged from 9 to 28.10 per 100,000 population per year (country-level studies), and 3.3 to 24.4 per 100,000 population per year (regional-level studies.) The most common mechanisms of injury were traffic accidents and falls. Over time, the contribution of traffic accidents to total TBI events may be reducing. Case ascertainment and definitions of TBI are variable. Improved standardization would enable more accurate comparisons.

Epidemiology of Traumatic Brain Injury in Europe: A Living Systematic Review

This systematic review provides a comprehensive, up-to-date summary of traumatic brain injury (TBI) epidemiology in Europe, describing incidence, mortality, age, and sex distribution, plus severity, mechanism of injury, and time trends. PubMed, CINAHL, EMBASE, and Web of Science were searched in January 2015 for observational, descriptive, English language studies reporting incidence, mortality, or case fatality of TBI in Europe. There were no limitations according to date, age, or TBI severity. Methodological quality was assessed using the Methodological Evaluation of Observational Research checklist. Data were presented narratively. Sixty-six studies were included in the review. Country-level data were provided in 22 studies, regional population or treatment center catchment area data were reported by 44 studies. Crude incidence rates varied widely. For all ages and TBI severities, crude incidence rates ranged from 47.3 per 100,000, to 694 per 100,000 population per year (country-level studies) and 83.3 per 100,000, to 849 per 100,000 population per year (regional-level studies). Crude mortality rates ranged from 9 to 28.10 per 100,000 population per year (country-level studies), and 3.3 to 24.4 per 100,000 population per year (regional-level studies.) The most common mechanisms of injury were traffic accidents and falls. Over time, the contribution of traffic accidents to total TBI events may be reducing. Case ascertainment and definitions of TBI are variable. Improved standardization would enable more accurate comparisons.

Neutral Chiral Tetrakis-Iodo-Triazole Halogen-Bond Donor for Chiral Recognition and Enantioselective Catalysis

Halogen bonding represents a powerful tool in the field of noncovalent interactions. However, applications in enantioselective recognition and catalysis remain almost nonexistent, due in part to the distinct features of halogen bonds, including long covalent and noncovalent bond distances and high directionality. Herein, this work presents a novel chiral tetrakis-iodo-triazole structure as a neutral halogen bond donor for both chiral anion-recognition and enantioinduction in ion-pair organocatalysis. NMR-titration studies revealed significant differences in anion affinity between the halogen bonding receptor and its hydrogen bonding parent. Selective recognition of chiral dicarboxylates and asymmetric induction in a benchmark organocatalytic reaction were demonstrated using the halogen bond donor. Inversions in the absolute sense of chiral recognition, enantioselectivity, and chiroptical properties relative to the related hydrogen donor were observed. Computational modeling suggested that these effects were the result of distinct anion-binding modes for the halogen- versus hydrogen-bond donors.

Recent advances in the direct O-arylation of carbohydrates

Methods for the O-arylation of hydroxyl and hemiacetal groups in carbohydrates via C(sp2)-O bond formation are discussed. Such methods provide an alternative disconnection to the traditional approach of nucleophilic substitution between a sugar-derived electrophile and a phenol or phenoxide nucleophile. They have led to new opportunities for stereoselectivity, site-selectivity and chemoselectivity in the preparation of O-aryl glycosides and carbohydrate-derived aryl ethers, compounds that are useful for a broad range of applications in medicinal chemistry, glycobiology and organic synthesis.

Development of an endothelial cell-restricted transgenic reporter rat: a resource for physiological studies of vascular biology

Here, we report the generation of a Cre-recombinase (iCre) transgenic rat, where iCre is driven using a vascular endothelial-cadherin (CDH5) promoter. The CDH5 promoter was cloned from rat pulmonary microvascular endothelial cells and demonstrated ~60% similarity to the murine counterpart. The cloned rat promoter was 2,508 bp, it extended 79 bp beyond the transcription start site, and it was 22,923 bp upstream of the translation start site. The novel promoter was cloned upstream of codon-optimized iCre and subcloned into a Sleeping Beauty transposon vector for transpositional transgenesis in Sprague-Dawley rats. Transgenic founders were generated and selected for iCre expression. Crossing the CDH5-iCre rat with a tdTomato reporter rat resulted in progeny displaying endothelium-restricted fluorescence. tdTomato fluorescence was prominent in major arteries and veins, and it was similar in males and females. Quantitative analysis of the carotid artery and the jugular vein revealed that, on average, more than 50% of the vascular surface area exhibited strong fluorescence. tdTomato fluorescence was observed in the circulations of every tissue tested. The microcirculation in all tissues tested displayed homogenous fluorescence. Fluorescence was examined across young (6-7.5 mo), middle (14-16.5 mo), and old age (17-19.5 mo) groups. Although tdTomato fluorescence was seen in middle- and old-age animals, the intensity of the fluorescence was significantly reduced compared with that seen in the young rats. Thus, this endothelium-restricted transgenic rat offers a novel platform to test endothelial microheterogeneity within all vascular segments, and it provides exceptional resolution of endothelium within-organ microcirculation for application to translational disease models.NEW & NOTEWORTHY The use of transgenic mice has been instrumental in advancing molecular insight of physiological processes, yet these models oftentimes do not faithfully recapitulate human physiology and pathophysiology. Rat models better replicate some human conditions, like Group 1 pulmonary arterial hypertension. Here, we report the development of an endothelial cell-restricted transgenic reporter rat that has broad application to vascular biology. This first-in-kind model offers exceptional endothelium-restricted tdTomato expression, in both conduit vessels and the microcirculations of organs.

Ablation of Endothelial TRPV4 Channels Alters the Dynamic Ca2+ Signaling Profile in Mouse Carotid Arteries

Transient receptor potential vanilloid 4 channels (TRPV4) are pivotal regulators of vascular homeostasis. Altered TRPV4 signaling has recently been implicated in various cardiovascular diseases, including hypertension and atherosclerosis. These versatile nonselective cation channels increase endothelial Ca²⁺ influx in response to various stimuli including shear stress and G protein-coupled receptor (GPCR) activation. Recent findings suggest TRPV4 channels produce localized Ca²⁺ transients at the endothelial cell plasma membrane that may allow targeted effector recruitment and promote large-scale Ca²⁺ events via release from internal stores (endoplasmic reticulum). However, the specific impact of TRPV4 channels on Ca²⁺ signaling in the intact arterial intima remains unknown. In the current study, we employ an endothelium-specific TRPV4 knockout mouse model (ecTRPV4^-/-) to identify and characterize TRPV4-dependent endothelial Ca²⁺ dynamics. We find that carotid arteries from both ecTRPV4^-/- and WT mice exhibit a range of basal and acetylcholine (ACh)-induced Ca²⁺ dynamics, similar in net frequency. Analysis of discrete Ca²⁺ event parameters (amplitude, duration, and spread) and event composite values reveals that while ecTRPV4^-/- artery endothelium predominantly produces large Ca²⁺ events comparable to and in excess of those produced by WT endothelium, they are deficient in a particular population of small events, under both basal and ACh-stimulated conditions. These findings support the concept that TRPV4 channels are responsible for generating a distinct population of focal Ca²⁺ transients in the intact arterial endothelium, likely underlying their essential role in vascular homeostasis.

Site-selective redox isomerizations of furanosides using a combined arylboronic acid/photoredox catalyst system

In the presence of an arylboronic acid and a hydrogen atom transfer mediator under photoredox conditions, furanoside derivatives undergo site-selective redox isomerizations to 2-keto-3-deoxyfuranosides. Experimental evidence and computational modeling suggest that the transformation takes place by abstraction of the hydrogen atom from the 2-position of the furanoside-derived arylboronic ester, followed by C3-O bond cleavage via spin-center shift. This mechanism is reminiscent of the currently accepted pathway for the formation of 3'-ketodeoxynucleotides by ribonucleotide reductase enzymes.

Seasonal patterns of traumatic brain injury deaths due to traffic-related incidents in the Slovak Republic

Objective: Traumatic Brain Injuries (TBIs) are an important type of injury in terms of both morbidity and mortality. Road Traffic Incidents are one of the most frequent causes of TBI. This analysis seeks to quantify the number of such injuries occurring in the Slovak Republic, and examine patterns of TBI according to mode of transport and seasonality.Methods: Data concerning total numbers of TBIs occurring from the years 1996-2015 were obtained from the Statistical Office of the Slovak Republic. The events caused by road incidents were examined separately according the external cause stated on death certification. Events were classified into seasons according to the month of death. Summary statistics were produced concerning numbers of deaths according to sex, mode of transport and season. Analyses were performed to examine trends in TBI by season and type of road user.Results: During a period of 20 years from 1996, there were 17,047 recorded deaths involving TBI in the Slovak Republic. Of these, 5,370 were caused by road traffic incidents (RTIs). Age standardized rates tended to decrease from 8.3/100,000/year (1996) to 2.5/100,000/year (2015). Males made up approximately 79% of road traffic-caused TBIs. Summer and autumn showed significantly more events than any other season, with motorcyclists and cyclists in particular being more frequently injured at this time of year.Conclusions: The results show that Slovakia, like many countries, suffers a considerable burden of TBI and that RTIs are a major contributor to this, especially among young adults. Rates of TBI vary by season in Slovakia, and users of different modes of transport appear more or less likely to suffer such injury during different seasons. Considerable variability in rates of injury exists between road users and times of year. Improved understanding of the timing and sufferers of injuries may allow better planning of response and care services. Further research into transport modes and policies aimed at safer driving should be explored.

Copper-mediated anomeric O-arylation with organoboron reagents

Copper-mediated couplings of arylboroxines with glycosyl hemiacetals furnish O-aryl glycosides via Csp2-O bond formation. The method enables the anomeric O-arylation of protected pyranose and furanose derivatives, and is tolerant of functionalized arylboroxine partners. Whereas mixtures of anomers are formed from glucopyranose, galactopyranose and arabinofuranose hemiacetals, the α-anomer is generated selectively from mannopyranose and mannofuranose-derived substrates.

Diarylborinic Acid-Catalyzed, Site-Selective Sulfation of Carbohydrate Derivatives

Sulfated carbohydrates have been implicated in diverse biological processes, with the position and extent of sulfation of a glycoside often playing important roles in determining the affinity and specificity of its binding to a biomolecular partner. Methods for the site-selective introduction of sulfate groups to carbohydrates are thus of interest. Here, we describe the development of a diarylborinic acid-catalyzed protocol for selective sulfation of pyranoside derivatives at the equatorial position of a cis-1,2-diol group. This method, which employs the sulfur trioxide-trimethylamine complex as the electrophile, has been employed for installation of a sulfate group at the 3-position of a range of galacto- and mannopyranosides, including substrates having a free primary OH group. By using a full equivalent of the diarylborinic acid, selective syntheses of more complex monosulfated glycosides, namely, a 3'-sulfolactose derivative and 3'-sulfo-β-galactosylceramide, have been accomplished. Preliminary kinetics experiments suggested that the catalyst resting state is a tetracoordinate diarylborinic ester that reacts with the SO₃ complex in the turnover-limiting step. Catalyst inhibition by the pyranoside sulfate product and trialkylamine byproduct of the reaction was demonstrated.