Publications by authors named "Pepper H"

Brown adipose tissue (BAT) engages futile fatty acid synthesis-oxidation cycling, the purpose of which has remained elusive. Here, we show that ATP-citrate lyase (ACLY), which generates acetyl-CoA for fatty acid synthesis, promotes thermogenesis by mitigating metabolic stress. Without ACLY, BAT overloads the tricarboxylic acid cycle, activates the integrated stress response (ISR) and suppresses thermogenesis.

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ATP citrate lyase (ACLY) is the predominant nucleocytosolic source of acetyl-CoA and is aberrantly regulated in many diseases making it an attractive therapeutic target. Structural studies of ACLY reveal a central homotetrameric core citrate synthase homology (CSH) module flanked by acyl-CoA synthetase homology (ASH) domains, with ATP and citrate binding the ASH domain and CoA binding the ASH-CSH interface to produce acetyl-CoA and oxaloacetate products. The specific catalytic role of the CSH module and an essential D1026A residue contained within it has been a matter of debate.

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Heart failure (HF) is a leading cause of mortality. Failing hearts undergo profound metabolic changes, but a comprehensive evaluation in humans is lacking. We integrate plasma and cardiac tissue metabolomics of 678 metabolites, genome-wide RNA-sequencing, and proteomic studies to examine metabolic status in 87 explanted human hearts from 39 patients with end-stage HF compared with 48 nonfailing donors.

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Developmental cardiac tissue is regenerative while operating under low oxygen. After birth, ambient oxygen is associated with cardiomyocyte cell cycle exit and regeneration. Likewise, cardiac metabolism undergoes a shift with cardiac maturation.

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Although DNA damage is intricately linked to metabolism, the metabolic alterations that occur in response to DNA damage are not well understood. We use a DNA repair-deficient model of ERCC1-XPF in to gain insights on how genotoxic stress drives aging. Using multi-omic approach, we discover that nuclear DNA damage promotes mitochondrial β-oxidation and drives a global loss of fat depots.

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Quantitative subcellular metabolomic measurements can explain the roles of metabolites in cellular processes but are subject to multiple confounding factors. We developed stable isotope labeling of essential nutrients in cell culture-subcellular fractionation (SILEC-SF), which uses isotope-labeled internal standard controls that are present throughout fractionation and processing to quantify acyl-coenzyme A (acyl-CoA) thioesters in subcellular compartments by liquid chromatography-mass spectrometry. We tested SILEC-SF in a range of sample types and examined the compartmentalized responses to oxygen tension, cellular differentiation, and nutrient availability.

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A series of cascade reactions of -quinone methides have been developed based on the proposed biosynthesis of busseihydroquinone and parvinaphthol meroterpenoid natural products. The polycyclic framework of the most complex family members, busseihydroquinone E and parvinaphthol C, was assembled by an intramolecular [4 + 2] cycloaddition of an electron-rich chromene substrate. The resultant cyclic enol ether underwent rearrangements under acidic or oxidative conditions, which led to a new total synthesis of rhodonoid D.

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The biosynthetic route to the napyradiomycin family of bacterial meroterpenoids has been fully described 32 years following their original isolation and 11 years after their gene cluster discovery. The antimicrobial and cytotoxic natural products napyradiomycins A1 and B1 are produced using three organic substrates (1,3,6,8-tetrahydroxynaphthalene, dimethylallyl pyrophosphate, and geranyl pyrophosphate), and catalysis via five enzymes: two aromatic prenyltransferases (NapT8 and T9); and three vanadium dependent haloperoxidase (VHPO) homologues (NapH1, H3, and H4). Building upon the previous characterization of NapH1, H3, and T8, we herein describe the initial (NapT9, H1) and final (NapH4) steps required for napyradiomycin construction.

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The naphterpins and marinones are naphthoquinone meroterpenoids with an unusual aromatic oxidation pattern that is biosynthesized from 1,3,6,8-tetrahydroxynaphthalene (THN). We propose that cryptic halogenation of THN derivatives by vanadium-dependent chloroperoxidase (VCPO) enzymes is key to this biosynthetic pathway, despite the absence of chlorine in these natural products. This speculation inspired a total synthesis to mimic the naphterpin/marinone biosynthetic pathway.

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Bacterial meroterpenoids constitute an important class of natural products with diverse biological properties and therapeutic potential. The biosynthetic logic for their production is unknown and defies explanation via classical biochemical paradigms. A large subgroup of naphthoquinone-based meroterpenoids exhibits a substitution pattern of the polyketide-derived aromatic core that seemingly contradicts the established reactivity pattern of polyketide phenol nucleophiles and terpene diphosphate electrophiles.

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The onset of new multidrug-resistant strains of bacteria demands continuous development of antibacterial agents with new chemical scaffolds and mechanisms of action. We present the first structure-activity relationship (SAR) study of 16 derivatives of a structurally novel antibiotic merochlorin A that were designed using a biosynthetic blueprint. Our lead compounds are active against several Gram-positive bacteria such as Staphylococcus aureus (SA), methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE) and Bacillus subtilis, inhibit intracellular growth of Mycobacterium bovis, and are relatively nontoxic to human cell lines.

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The synthesis of verrubenzospirolactone from its proposed biosynthetic precursor, capillobenzopyranol, has been shown to be chemically feasible via a simple reaction sequence. The key steps are a chemoselective furan oxidation mediated by NaClO, a stereoselective dehydration of a γ-methoxybutenolide, and an intramolecular Diels-Alder reaction.

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A five-step total synthesis of (±)-verrubenzospirolactone has been achieved using a biomimetic, intramolecular Diels-Alder reaction of a 2H-chromene to form two rings and four stereocenters in the final step. This Diels-Alder reaction occurs spontaneously at 30 °C "on-water", and thus suggests that it is likely to be non-enzymatic in nature. The structure of (±)-verrubenzospirolactone was also used to inspire a quadruple cascade reaction to generate seven stereocenters, four rings, three C-C bonds, and two C-O bonds in one step.

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A case of tuberculosis presenting as a neck lump is highlighted. Tuberculosis is on the increase. There are national and international strategies to improve the management of tuberculosis in the United Kingdom, and raising clinical awareness of tuberculosis is an important part of that strategy.

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Gentle Persuasive Approaches in Dementia Care (GPA), a curriculum originally designed for long-term care, was introduced into an acute care setting. This person-centered approach to supporting and responding to persons with behaviors associated with dementia was shown to be applicable for staff on an orthopaedic surgery unit where they had reported significant challenges and care burdens when faced with behaviors such as shouting, explosiveness, and resistance to care. Staff confidence in their ability to care for persons with behaviors increased after attending the 1-day GPA workshop, and they reported being highly satisfied with the curriculum, found it to be applicable to their practice, indicated that it was also useful for patients with delirium, and would recommend it to others.

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A full account of our oxidative radical cyclization approach to the synthesis of garcibracteatone and doitunggarcinone A is presented. This includes the first enantioselective synthesis of garcibracteatone, which allowed the absolute configuration of the natural compound to be determined. The first synthesis of doitunggarcinone A is also described, which confirms our reassignment of the relative configuration of this molecule.

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Objective : To establish for the first time the prevalence of fistula symptoms and the effectiveness of secondary alveolar bone grafting to treat these symptoms in a single surgeon cohort in Bristol, United Kingdom. Design : Direct questioning of 233 consecutive patients with cleft before and after secondary alveolar bone grafting as to the presence of fistula symptoms. Setting : Southwest and South Wales Cleft Centre, Frenchay Hospital, Bristol, United Kingdom.

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The polycyclic polyprenylated acylphloroglucinol natural product garcibracteatone has been synthesized in four steps from phloroglucinol, using a strategy based on biosynthetic speculation. The key biomimetic transformation is a cascade of 7-endo-trig and 5-exo-trig radical cyclizations followed by a terminating aromatic substitution reaction.

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A total synthesis of the marine sponge meroterpenoid (+)-aureol has been achieved in 12 steps (6% overall yield) from (+)-sclareolide. Key steps of the synthesis include a biosynthetically inspired sequence of 1,2-hydride and methyl shifts, and a biomimetic cycloetherification reaction.

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A hypothesis for the biosynthesis of the frondosins A-E is presented. Synthesis of a liphagal-frondosin C hybrid molecule has been achieved, with the frondosin C 6-7-5-6 ring system being constructed by a photochemical process that follows an intramolecular Paternò-Büchi reaction/fragmentation pathway.

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