Discovery and Characterization of the Fully Decorated Nocardiosis-Associated Polyketide Natural Product.

The genomes of 40 strains of Nocardia, most of which were associated with life-threatening human infections, encode a highly conserved assembly line polyketide synthase designated as the NOCAP (NOCardiosis-Associated Polyketide) synthase, whose product structure has been previously described. Here we report the structure and inferred biosynthetic pathway of the fully decorated glycolipid natural product. Its structure reveals a fully substituted benzaldehyde headgroup harboring an unusual polyfunctional tail and an O-linked disaccharide comprising a 3-α-epimycarose and 2-O-methyl-α-rhamnose whose installation requires flavin monooxygenase-dependent hydroxylation of the polyketide product. Production of the fully decorated glycolipid was verified in cultures of two patient-derived Nocardia species. In both E. coli and Nocardia spp., the glycolipid was only detected in culture supernatants, consistent with data from genetic knockout experiments implicating roles for two dedicated proteins in installing the second sugar substituent only after the monoglycosyl intermediate is exported across the bacterial cell membrane. With the NOCAP product in hand, the stage is set for investigating the evolutionary benefit of this polyketide biosynthetic pathway for Nocardia strains capable of infecting human hosts.

A Silymarin Antioxidant Serum Improves Facial Acne Alone and as Part of a Treatment Regimen.

BACKGROUND: Silymarin is an antioxidant that can protect against free radicals that cause premature signs of aging and oil oxidation that may contribute to breakouts. AIMS: The objective of these studies was to evaluate a silymarin antioxidant serum alone and in combination with a prescription acne treatment regimen in improving facial appearance in blemish-prone skin.  Methods: Two international studies were conducted. A 12-week study in Brazil enrolled 56 subjects to examine the effect of silymarin antioxidant serum on facial acne. Clinical grading on acne lesions, skin tone, clarity, and postinflammatory hyperpigmentation (PIH) were conducted. In addition, consumer self-assessment, analysis for markers of lipid peroxidation, and sebumeter analysis were completed. Another Unites States (US)/German study enrolled 40 subjects who were on topical prescription acne medications to which silymarin antioxidant serum was added. Acne lesion counts, tolerability, and facial appearance assessments were conducted in this study. RESULTS: The Brazilian study demonstrated a 45% reduction in inflammatory lesions and a 43% reduction in noninflammatory lesions after 12 weeks of silymarin antioxidant serum use. In addition, sebumeter testing showed a 16% reduction in oiliness at week 1. The US/German study showed the benefits of the serum in persons already on prescription acne therapy by reducing facial erythema by 60%, dryness by 49%, and scaling by 67%. CONCLUSION: Silymarin is shown in clinical testing to have significant benefits in reducing lipid peroxidation, oiliness, and PIH, and in improving key markers of skin aging. Additionally, the serum can be used alone or as an adjunctive treatment in acne therapy to further benefit aging, acne-prone skin. J Drugs Dermatol. 2024;23(4):     doi:10.36849/JDD.8120.

Risk factors for percutaneous left ventricular assist device explant complications.

INTRODUCTION: Percutaneous left ventricular assist device (pLVAD) explant remains nonstandardized with potential complications of bleeding and thrombosis. Explant settings include percutaneous techniques in the catheterization laboratory (CL), manually at bedside (MB), and surgically in the operating room (OR). OBJECTIVE: Identify high-risk features for explant-related complications, including indication for support, setting, and technique. METHODS: Postexplant bleeding and thrombosis/limb ischemia were identified following pLVAD removals over 2 years at a multicenter healthcare system. RESULTS: Of 156 patients, bleeding (n = 26 [17%]) and thrombosis (n = 9 [6%]) occurred more often in patients with the peripheral arterial disease (PAD), female gender, anemia, and cardiogenic shock. OR explants had a higher combined endpoint (4/8 [50%]) versus CL (23/133 [17%], p < 0.05) driven by transfusion. There was no difference between OR versus MB (5/15 [33%], p = 0.66) or CL versus MB (p = 0.62). In shock patients, there was no difference between CL (7/30 [23%]) versus MB (5/15 [33%], p = 0.5) and OR (4/7 [57%], p = 0.16); or MB versus OR (p = 0.38). Average length of stay was significantly lower in the CL group versus MB and OR (3.6 ± 33.2 vs. 18.4 ± 10.9 vs. 28.1 ± 15.8 days, p < 0.0001). Preclosure in shock patients (5/25 [20%] vs. 11/27 [41%], p = 0.1383) and crossover balloon occlusion technique (9/44 [16%] vs. 25/112 [22%]; p = 1) were not associated with higher combined endpoints versus control. CONCLUSION: Risk factors for pLVAD explant complications include PAD, female gender, and cardiogenic shock. There was no difference in complication rates between explant settings among cardiogenic shock patients, but shorter length of stay when performed in the CL. There was no difference in complication rates when using the crossover balloon occlusion technique.

Alteration to the Skin Ceramide Profile Following Broad-Spectrum UV Exposure.

The epidermal stratum corneum (SC) lipid matrix, principally consisting of an equimolar ratio of ceramides, free fatty acids, and cholesterol, plays a crucial role in maintaining proper skin barrier function. Conditions which impair barrier integrity, such as in atopic dermatitis, correlate with the alternation of key ceramide subclasses and reduced chain length of acyl moieties. However, there is limited knowledge about the impact of unprotected repeat sun exposure on the skin lipid composition, especially ceramide profiles.This study investigated the effects of ultraviolet (UV) radiation on the ceramide profile using both an ex vivo skin and a clinical model. Lipidomic analysis of UV-exposed skin showed shifts to the composition of ceramide subclasses essential in repairing and strengthening the SC barrier (including CER1[EOS], CER3[NP], and CER6[AP]) and reduced very long-chain acyl moieties. Gene expression analysis and immunohistochemical staining of key enzymes (aSMase, DES1, CerS5, CerS3) suggested that lipid alterations can be attributed to changes within the ceramide biosynthesis process. Topical application of ceramide-containing suncare products help maintain SC-essential ceramide subclasses and proper ceramide chain length, demonstrating the importance of proper photoprotection to maintain healthy skin barrier and ceramide quality during daily sun exposure. J Drugs Dermatol. 2022;21(1):77-85. doi:10.36849/JDD.6331.

Properties of a "Split-and-Stuttering" Module of an Assembly Line Polyketide Synthase.

Notwithstanding the "one-module-one-elongation-cycle" paradigm of assembly line polyketide synthases (PKSs), some PKSs harbor modules that iteratively elongate their substrates through a defined number of cycles. While some insights into module iteration, also referred to as "stuttering", have been derived through in vivo and in vitro analysis of a few PKS modules, a general understanding of the mechanistic principles underlying module iteration remains elusive. This report serves as the first interrogation of a stuttering module from a trans-AT subfamily PKS that is also naturally split across two polypeptides. Previous work has shown that Module 5 of the NOCAP (nocardiosis associated polyketide) synthase iterates precisely three times in the biosynthesis of its polyketide product, resulting in an all-trans-configured triene moiety in the polyketide product. Here, we describe the intrinsic catalytic properties of this NOCAP synthase module. Through complementary experiments in vitro and in E. coli, the "split-and-stuttering" module was shown to catalyze up to five elongation cycles, although its dehydratase domain ceased to function after three cycles. Unexpectedly, the central olefinic group of this truncated product had a cis configuration. Our findings set the stage for further in-depth analysis of a structurally and functionally unusual PKS module with contextual biosynthetic plasticity.

Proteomic profiling of murine biliary-derived hepatic organoids and their capacity for drug disposition, bioactivation and detoxification.

Hepatic organoids are a recent innovation in in vitro modeling. Initial studies suggest that organoids better recapitulate the liver phenotype in vitro compared to pre-existing proliferative cell models. However, their potential for drug metabolism and detoxification remains poorly characterized, and their global proteome has yet to be compared to their tissue of origin. This analysis is urgently needed to determine what gain-of-function this new model may represent for modeling the physiological and toxicological response of the liver to xenobiotics. Global proteomic profiling of undifferentiated and differentiated hepatic murine organoids and donor-matched livers was, therefore, performed to assess both their similarity to liver tissue, and the expression of drug-metabolizing enzymes and transporters. This analysis quantified 4405 proteins across all sample types. Data are available via ProteomeXchange (PXD017986). Differentiation of organoids significantly increased the expression of multiple cytochrome P450, phase II enzymes, liver biomarkers and hepatic transporters. While the final phenotype of differentiated organoids is distinct from liver tissue, the organoids contain multiple drug metabolizing and transporter proteins necessary for liver function and drug metabolism, such as cytochrome P450 3A, glutathione-S-transferase alpha and multidrug resistance protein 1A. Indeed, the differentiated organoids were shown to exhibit increased sensitivity to midazolam (10-1000 µM) and irinotecan (1-100 µM), when compared to the undifferentiated organoids. The predicted reduced activity of HNF4A and a resulting dysregulation of RNA polymerase II may explain the partial differentiation of the organoids. Although further experimentation, optimization and characterization is needed relative to pre-existing models to fully contextualize their use as an in vitro model of drug-induced liver injury, hepatic organoids represent an attractive novel model of the response of the liver to xenobiotics. The current study also highlights the utility of global proteomic analyses for rapid and accurate evaluation of organoid-based test systems.

ARTICLE: Alteration to the Skin Barrier Integrity Following Broad-Spectrum UV Exposure in an Ex Vivo Tissue Model.

Dynamic changes to the skin barrier’s molecular structure and ceramide profile are well-documented in skin conditions such as atopic dermatitis and psoriasis. Pathological and environmental factors have been shown to impair barrier integrity and demonstrate shifts in ceramide composition in the skin. However, the relationship between acute and prolonged sun exposure and its effects on skin barrier homeostasis is insufficiently investigated. This study aims to uncover new scientific evidence to elucidate the relationship of UV irradiation with the skin barrier using an ex vivo tissue model following simulated UVA/UVB exposure. Fresh ex vivo human skin pretreated either with or without a broad-spectrum sunscreen was exposed to either a physiological or elevated UV condition. Following eight days in culture, structural and molecular changes were evaluated. UV irradiated skin displayed epidermal cell death and altered expression of key barrier proteins. TEM analysis demonstrated disruption to adherens junctions and dissociation between tissue layers following both physiological and extensive UV exposures. An effective broad-spectrum sunscreen containing essential skin ceramides completely protected the skin from such changes. This is one of the first works demonstrating a clear correlation of altered skin barrier integrity using a physiologically relevant dose in an ex vivo tissue model. Our findings also further support the additional importance and benefits of sun protection among the consumers. J Drugs Dermatol. 20(4 Suppl):s23-28. doi:10.36849/JDD.S589D.

ARTICLE: Efficacy of Ceramide-Containing Formulations on UV-Induced Skin Surface Barrier Alterations.

The human skin, particularly the stratum corneum, serves as a protective barrier against exogenous factors, including ultraviolet radiation (UVR) and pathogen invasions. The impact of UVR on skin cancer and photoaging has been extensively studied. However, the direct impact of UVR on skin barrier integrity under clinical settings remains poorly explored. Due to their benefits in reducing inflammation and promoting skin barrier repair, ceramide-containing formulations can provide added photoprotection benefits. In this study, the efficacy of a ceramide-containing sunscreen and moisturizer were evaluated in preventing UV-induced skin surface barrier changes. Expert grading, instrumental, and tape-stripping assessments demonstrated that UVR induced erythema and hyperpigmentation and caused changes in skin cells surface morphological organization and maturation. Treatment with a ceramide-containing sunscreen and moisturizing cream routine reduced erythema and hyperpigmentation, improved skin hydration, and maintained normal superficial skin cells morphology and turnover after UVR. Our results indicate that barrier-enforcing lipids formulations can provide additional benefits in patient’s daily routine by strengthening the barrier and improving skin health overall against chronic sun exposure. J Drugs Dermatol. 20(4 Suppl):s29-35. doi:10.36849/JDD.S589E.

Complete Reconstitution and Deorphanization of the 3 MDa Nocardiosis-Associated Polyketide Synthase.

Several Nocardia strains associated with nocardiosis, a potentially life-threatening disease, house a nonamodular assembly line polyketide synthase (PKS) that presumably synthesizes an unknown polyketide. Here, we report the discovery and structure elucidation of the NOCAP (nocardiosis-associated polyketide) aglycone by first fully reconstituting the NOCAP synthase in vitro from purified protein components followed by heterologous expression in E. coli and spectroscopic analysis of the purified products. The NOCAP aglycone has an unprecedented structure comprised of a substituted resorcylaldehyde headgroup linked to a 15-carbon tail that harbors two conjugated all-trans trienes separated by a stereogenic hydroxyl group. This report is the first example of reconstituting a trans-acyltransferase assembly line PKS in vitro and of using these approaches to "deorphanize" a complete assembly line PKS identified via genomic sequencing. With the NOCAP aglycone in hand, the stage is set for understanding how this PKS and associated tailoring enzymes confer an advantage to their native hosts during human Nocardia infections.

Stem cell models as an in vitro model for predictive toxicology.

Adverse drug reactions (ADRs) are the unintended side effects of drugs. They are categorised as either predictable or unpredictable drug-induced injury and may be exhibited after a single or prolonged exposure to one or multiple compounds. Historically, toxicology studies rely heavily on animal models to understand and characterise the toxicity of novel compounds. However, animal models are imperfect proxies for human toxicity and there have been several high-profile cases of failure of animal models to predict human toxicity e.g. fialuridine, TGN1412 which highlight the need for improved predictive models of human toxicity. As a result, stem cell-derived models are under investigation as potential models for toxicity during early stages of drug development. Stem cells retain the genotype of the individual from which they were derived, offering the opportunity to model the reproducibility of rare phenotypes in vitro Differentiated 2D stem cell cultures have been investigated as models of hepato- and cardiotoxicity. However, insufficient maturity, particularly in the case of hepatocyte-like cells, means that their widespread use is not currently a feasible method to tackle the complex issues of off-target and often unpredictable toxicity of novel compounds. This review discusses the current state of the art for modelling clinically relevant toxicities, e.g. cardio- and hepatotoxicity, alongside the emerging need for modelling gastrointestinal toxicity and seeks to address whether stem cell technologies are a potential solution to increase the accuracy of ADR predictivity in humans.

Impact of Iron-Oxide Containing Formulations Against Visible Light-Induced Skin Pigmentation in Skin of Color Individuals.

Visible light (400-700nm), which contributes to 45% of solar radiation, contributes to skin darkening and worsening of dyschromias, particularly in individuals with Fitzpatrick skin phototypes III and higher. Currently, sunscreens provide limited protection against that spectrum. Due to their capabilities in absorbing, scattering, and reflecting visible light, topical products containing pigments and/or metal oxides can provide additional photoprotection. In this study, the efficacy of two formulations containing iron oxide was evaluated in preventing visible light-induced pigmentation compared with a non-tinted mineral SPF 50+ sunscreen. Expert grading and colorimetry demonstrated that the iron-oxide containing formulations significantly protected against visible light-induced pigmentation compared to untreated skin or mineral SPF 50+ sunscreen in Fitzpatrick IV individuals. These results highlight that iron-oxide containing formulas in a foundation format have dual functions and can provide additional benefits in patients' daily routine by masking existing pigmentation and preventing the development of pigmentation triggered by sunlight exposure, extending protection beyond UV spectrum. J Drugs Dermatol. 2020;19(7): doi:10.36849/JDD.2020.5032 THIS ARTICLE HAD BEEN MADE AVAILABLE FREE OF CHARGE. PLEASE SCROLL DOWN TO ACCESS THE FULL TEXT OF THIS ARTICLE WITHOUT LOGGING IN. NO PURCHASE NECESSARY. PLEASE CONTACT THE PUBLISHER WITH ANY QUESTIONS.

Weight-based tacrolimus trough concentrations post liver transplant.

BACKGROUND: Tacrolimus is one of the most widely used liver transplant medications. With the increasing number of obese patients requiring liver transplants, knowledge of the effect of body size affecting post-transplant outcomes, for example drug exposure is increasingly required. AIMS: (i) To investigate whether patient body size (i.e. total bodyweight) affects trough plasma concentrations of tacrolimus when a standard mg/kg dosing regimen is used; and (ii) to investigate whether obese patients have different numbers of plasma concentrations outside the therapeutic range compared to non-obese patients in the first months after liver transplant. METHODS: Using a transplant database, data tacrolimus concentrations were available for 69 patients. Tacrolimus was initially dosed at a standard 0.1 mg/kg/day after liver transplant, and adjusted to maintain a target trough concentration. Trough blood samples, phenotypic and outcome variables were analysed. RESULTS: Trough concentrations were similar between obese and non-obese patients (P > 0.05) at each sampling day. At day 7 post-transplant, 85.7% and 79.5% of the observed plasma concentrations were outside the recommended therapeutic range for obese and non-obese patients respectively, at day 30, 52.9% and 57.4%, and at 6 months, 18.7% and 27.5%. CONCLUSION: In the first week post-transplant, tacrolimus trough concentrations after standard mg/kg dosing post liver transplant appear to be corrected by total bodyweight. Obese patients have a similar number of trough plasma concentrations outside the therapeutic range compared to non-obese patients.

Effect of a Tranexamic Acid, Kojic Acid, and Niacinamide Containing Serum on Facial Dyschromia: A Clinical Evaluation

Background: Stubborn dyschromia such as melasma and post-inflammatory hyperpigmentation (PIH) are leading causes for cosmetic consultation. Topical treatment is challenging, using a range of modalities, to stop, hinder, and/or prevent steps in the pigment production process. Tranexamic acid (TXA), a potent plasmin inhibitor, is proposed to control pigmentation by inhibiting the release of inflammatory mediators involved in triggering melanogenesis. TXA has been recently introduced as a topical therapy aimed at reducing pigmentation in melasma. Methods: In a 12-week clinical study, a novel, topical facial serum containing 3% TXA, 1% kojic acid, and 5% niacinamide was evaluated for its effectiveness in treating melasma, PIH, and hyperpigmentation in Brazilian female subjects with Fitzpatrick skin types I-IV. Efficacy evaluations were performed at pre-treatment baseline, weeks 2, 4, 8, and 12, and included expert clinical grading, bio-instrumental measurements, and self-assessment questionnaires. Cutaneous tolerability was also evaluated by assessing subjective and objective irritation of the treatment area. Results: A significant improvement in the appearance of PIH, hyperpigmentation, melasma, skin texture, and skin tone homogeneity was observed beginning at week 2 and continued through week 12. Melanin index, as measured by Mexameter®, demonstrated a significant decrease by week 12 as compared to both pre-treatment baseline and control. Conclusions: The findings suggest that the test product is an effective and well-tolerated treatment option for addressing hyperpigmentary conditions, including melasma. Additional in vitro data suggests that TXA may act by mediating the inhibition of PGE2-stimulated human epidermal melanocytes. J Drugs Dermatol. 2019;18(5):454-459.

An Alkaloid from Scorpion Venom: Chemical Structure and Synthesis.

While most scorpion venom components identified in the past are peptidic or proteinic in nature, we report here a new alkaloid isolated from the venom of the Mexican scorpion Megacormus gertschi. Nuclear magnetic resonance and mass spectrometric investigations elucidate the structure of the alkaloid as ( Z)- N-(2-(1 H-imidazol-4-yl)ethyl)-3-(4-hydroxy-3-methoxyphenyl)-2-methoxyacrylamide (1). A chemical method of synthesizing this alkaloid is also described. Although abundant in venom, the above alkaloid was not found to have insecticidal activity. Structural analysis suggests that this venom alkaloid might be of potential interest for evaluating its medicinal effect.

Clinical Evaluation of a Multi-Modal Facial Serum That Addresses Hyaluronic Acid Levels in Skin.

BACKGROUND: Hyaluronic acid (HA), the major glycosaminoglycan present in the human skin, is a key contributor to water retention and mechanical support in skin. The level, size, and functionality of cutaneous HA are known to diminish with age. Topical treatments designed to increase the HA content of skin have been met with limited success. The purpose of this study was to evaluate the tolerance and efficacy of a multi-modal facial serum containing HA, Proxylane (C-Xyloside), purple rice extract, and dipotassium glycyrrhizate in addressing HA levels in skin. METHODS: A 12-week, single center, clinical study was conducted on 59 women with mild to moderate photodamage. Clinical grading to assess the efficacy and tolerability was conducted on the face at baseline and at weeks 4, 8, and 12. Bioinstrumentation measurements were taken, including corneometer, tewameter, ultrasound, and standardized digital imaging. A randomized subset of 20 subjects from the study population had 3 mm punch biopsies collected for quantitative RT-PCR analysis from 2 sites on the face at baseline and week 12. Additionally, a 4-week, single center, clinical study was conducted on the photodamaged forearms of 12 subjects. At both baseline and week 4, a 4 mm punch biopsy was obtained from the subjects' randomized forearms. Biopsy samples were subjected to immunohistochemical staining and analysis of HA content. RESULTS: Statistically-significant improvements in all facial skin attributes (weeks 4, 8, and 12), stratum corneum hydration (week 12), and transepidermal water loss (week 12) were observed. Tolerability was excellent, with no increases in irritation parameters noted. A significant increase of HA content in skin after 4 weeks of treatment was observed. By PCR analysis, there was a significant increase in hyaluronan synthase 2, as well as a significant increase in collagen type 1a1 after 12 weeks of application. CONCLUSION: The findings suggest that this novel topical facial serum is capable of stimulating HA and skin extracellular matrix components, as well as improving skin hydration and skin quality in women with mild to moderate photodamage.

J Drugs Dermatol. 2017;16(9):884-890.

External cavity diode laser based upon an FBG in an integrated optical fiber platform.

An external cavity diode laser is demonstrated using a Bragg grating written into a novel integrated optical fiber platform as the external cavity. The cavity is fabricated using flame-hydrolysis deposition to bond a photosensitive fiber to a silica-on-silicon wafer, and a grating written using direct UV-writing. The laser operates on a single mode at the acetylene P13 line (1532.83 nm) with 9 mW output power. The noise properties of the laser are characterized demonstrating low linewidth operation (< 14 kHz) and superior relative intensity noise characteristics when compared to a commercial tunable external cavity diode laser.

Enhanced efficacy of a topical antioxidants regimen in conjunction with a home-use non-ablative fractional diode laser in photodamaged facial skin.

BACKGROUND: Photodamaged facial skin is characterized by fine lines and wrinkles, mottled pigmentation, and other changes. OBJECTIVE: To evaluate and compare the efficacy and tolerance of a home-use laser device when used alone or in combination with an antioxidant facial treatment for moderate photodamage. METHODS: This was a 49-subject, evaluator-blinded, split-face, randomized, single-center, 24-week, phase-2, study. In phase 1, all subjects were treated on one facial side with test products and a home-use laser device and the other side was treated with laser alone for 12 weeks, followed by a 2-week regression period during which they used only support materials. For phase 2, all subjects were divided into 2 independent treatment groups. For the next 10 weeks, subjects of first group treated the assigned facial side with test products and support materials and the other facial side with only support materials. Subjects in the second group treated their entire face with only support materials. Efficacy and tolerance were assessed by clinical grading, VISIA-CR imaging, and self-assessment questionnaires. RESULTS: The combination of laser and test products improved all photodamage parameters evaluated. CONCLUSION: The test products enhanced and prolonged clinical benefits obtained with the laser alone.

The differential palmitoylation states of N-Ras and H-Ras determine their distinct Golgi subcompartment localizations.

Despite a high degree of structural homology and shared exchange factors, effectors and GTPase activating proteins, a large body of evidence suggests functional heterogeneity among Ras isoforms. One aspect of Ras biology that may explain this heterogeneity is the differential subcellular localizations driven by the C-terminal hypervariable regions of Ras proteins. Spatial heterogeneity has been documented at the level of organelles: palmitoylated Ras isoforms (H-Ras and N-Ras) localize on the Golgi apparatus whereas K-Ras4B does not. We tested the hypothesis that spatial heterogeneity also exists at the sub-organelle level by studying the localization of differentially palmitoylated Ras isoforms within the Golgi apparatus. Using confocal, live-cell fluorescent imaging and immunogold electron microscopy we found that, whereas the doubly palmitoylated H-Ras is distributed throughout the Golgi stacks, the singly palmitoylated N-Ras is polarized with a relative paucity of expression on the trans Golgi. Using palmitoylation mutants, we show that the different sub-Golgi distributions of the Ras proteins are a consequence of their differential degree of palmitoylation. Thus, the acylation state of Ras proteins controls not only their distribution between the Golgi apparatus and the plasma membrane, but also their distribution within the Golgi stacks.

Structure and thermodynamics of N6-methyladenosine in RNA: a spring-loaded base modification.

N(6)-Methyladenosine (m(6)A) modification is hypothesized to control processes such as RNA degradation, localization, and splicing. However, the molecular mechanisms by which this occurs are unclear. Here, we measured structures of an RNA duplex containing m(6)A in the GGACU consensus, along with an unmodified RNA control, by 2D NMR. The data show that m(6)A-U pairing in the double-stranded context is accompanied by the methylamino group rotating from its energetically preferred syn geometry on the Watson-Crick face to the higher-energy anti conformation, positioning the methyl group in the major groove. Thermodynamic measurements of m(6)A in duplexes reveal that it is destabilizing by 0.5-1.7 kcal/mol. In contrast, we show that m(6)A in unpaired positions base stacks considerably more strongly than the unmodified base, adding substantial stabilization in single-stranded locations. Transcriptome-wide nuclease mapping of methylated RNA secondary structure from human cells reveals a structural transition at methylated adenosines, with a tendency to single-stranded structure adjacent to the modified base.

Dibenzazepines and dibenzoxazepines as sodium channel blockers.

We have identified two related series of dibenzazepine and dibenzoxazepine sodium channel blockers, which showed good potency on Nav1.7 in FLIPR-based and electrophysiological functional assays.