Gut microbiome and metabolome profiling in Framingham heart study reveals cholesterol-metabolizing bacteria.

Accumulating evidence suggests that cardiovascular disease (CVD) is associated with an altered gut microbiome. Our understanding of the underlying mechanisms has been hindered by lack of matched multi-omic data with diagnostic biomarkers. To comprehensively profile gut microbiome contributions to CVD, we generated stool metagenomics and metabolomics from 1,429 Framingham Heart Study participants. We identified blood lipids and cardiovascular health measurements associated with microbiome and metabolome composition. Integrated analysis revealed microbial pathways implicated in CVD, including flavonoid, γ-butyrobetaine, and cholesterol metabolism. Species from the Oscillibacter genus were associated with decreased fecal and plasma cholesterol levels. Using functional prediction and in vitro characterization of multiple representative human gut Oscillibacter isolates, we uncovered conserved cholesterol-metabolizing capabilities, including glycosylation and dehydrogenation. These findings suggest that cholesterol metabolism is a broad property of phylogenetically diverse Oscillibacter spp., with potential benefits for lipid homeostasis and cardiovascular health.

Biomolecular analyses enable new insights into ancient Egyptian embalming.

The ability of the ancient Egyptians to preserve the human body through embalming has not only fascinated people since antiquity, but also has always raised the question of how this outstanding chemical and ritual process was practically achieved. Here we integrate archaeological, philological and organic residue analyses, shedding new light on the practice and economy of embalming in ancient Egypt. We analysed the organic contents of 31 ceramic vessels recovered from a 26th Dynasty embalming workshop at Saqqara1,2. These vessels were labelled according to their content and/or use, enabling us to correlate organic substances with their Egyptian names and specific embalming practices. We identified specific mixtures of fragrant or antiseptic oils, tars and resins that were used to embalm the head and treat the wrappings using gas chromatography-mass spectrometry analyses. Our study of the Saqqara workshop extends interpretations from a micro-level analysis highlighting the socio-economic status of a tomb owner3-7 to macro-level interpretations of the society. The identification of non-local organic substances enables the reconstruction of trade networks that provided ancient Egyptian embalmers with the substances required for mummification. This extensive demand for foreign products promoted trade both within the Mediterranean8-10 (for example, Pistacia and conifer by-products) and with tropical forest regions (for example, dammar and elemi). Additionally, we show that at Saqqara, antiu and sefet-well known from ancient texts and usually translated as 'myrrh' or 'incense'11-13 and 'a sacred oil'13,14-refer to a coniferous oils-or-tars-based mixture and an unguent with plant additives, respectively.

Glioma-induced inhibition of caspase-3 in microglia promotes a tumor-supportive phenotype.

Glioma cells recruit and exploit microglia (the resident immune cells of the brain) for their proliferation and invasion ability. The underlying molecular mechanism used by glioma cells to transform microglia into a tumor-supporting phenotype has remained elusive. We found that glioma-induced microglia conversion was coupled to a reduction in the basal activity of microglial caspase-3 and increased S-nitrosylation of mitochondria-associated caspase-3 through inhibition of thioredoxin-2 activity, and that inhibition of caspase-3 regulated microglial tumor-supporting function. Furthermore, we identified the activity of nitric oxide synthase 2 (NOS2, also known as iNOS) originating from the glioma cells as a driving stimulus in the control of microglial caspase-3 activity. Repression of glioma NOS2 expression in vivo led to a reduction in both microglia recruitment and tumor expansion, whereas depletion of microglial caspase-3 gene promoted tumor growth. Our results provide evidence that inhibition of the denitrosylation of S-nitrosylated procaspase-3 mediated by the redox protein Trx2 is a part of the microglial pro-tumoral activation pathway initiated by glioma cancer cells.

TDP-43 Nuclear Bodies: A NEAT Response to Stress?

In this issue of Molecular Cell, Wang et al. (2020) investigate stress-induced nuclear condensates of the RNA-binding protein TDP-43, uncovering a protective function for these granules as well as an RNA-dependent mechanism for scaffolding them.

CRISPR-Cas9 In Vivo Gene Editing of KLKB1 for Hereditary Angioedema.

BACKGROUND: Hereditary angioedema is a rare genetic disease that leads to severe and unpredictable swelling attacks. NTLA-2002 is an in vivo gene-editing therapy based on clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9. NTLA-2002 targets the gene encoding kallikrein B1 (KLKB1), with the goal of lifelong control of angioedema attacks after a single dose. METHODS: In this phase 1 dose-escalation portion of a combined phase 1-2 trial of NTLA-2002 in adults with hereditary angioedema, we administered NTLA-2002 at a single dose of 25 mg, 50 mg, or 75 mg. The primary end points were the safety and side-effect profile of NTLA-2002 therapy. Secondary and exploratory end points included pharmacokinetics, pharmacodynamics, and clinical efficacy determined on the basis of investigator-confirmed angioedema attacks. RESULTS: Three patients received 25 mg of NTLA-2002, four received 50 mg, and three received 75 mg. At all dose levels, the most common adverse events were infusion-related reactions and fatigue. No dose-limiting toxic effects, serious adverse events, grade 3 or higher adverse events, or clinically important laboratory findings were observed after the administration of NTLA-2002. Dose-dependent reductions in the total plasma kallikrein protein level were observed between baseline and the latest assessment, with a mean percentage change of -67% in the 25-mg group, -84% in the 50-mg group, and -95% in the 75-mg group. The mean percentage change in the number of angioedema attacks per month between baseline and weeks 1 through 16 (primary observation period) was -91% in the 25-mg group, -97% in the 50-mg group, and -80% in the 75-mg group. Among all the patients, the mean percentage change in the number of angioedema attacks per month from baseline through the latest assessment was -95%. CONCLUSIONS: In this small study, a single dose of NTLA-2002 led to robust, dose-dependent, and durable reductions in total plasma kallikrein levels, and no severe adverse events were observed. In exploratory analyses, reductions in the number of angioedema attacks per month were observed at all dose levels. (Funded by Intellia Therapeutics; ClinicalTrials.gov number, NCT05120830.).

Distinct Roles for Condensin's Two ATPase Sites in Chromosome Condensation.

Condensin is a conserved SMC complex that uses its ATPase machinery to structure genomes, but how it does so is largely unknown. We show that condensin's ATPase has a dual role in chromosome condensation. Mutation of one ATPase site impairs condensation, while mutating the second site results in hyperactive condensin that compacts DNA faster than wild-type, both in vivo and in vitro. Whereas one site drives loop formation, the second site is involved in the formation of more stable higher-order Z loop structures. Using hyperactive condensin I, we reveal that condensin II is not intrinsically needed for the shortening of mitotic chromosomes. Condensin II rather is required for a straight chromosomal axis and enables faithful chromosome segregation by counteracting the formation of ultrafine DNA bridges. SMC complexes with distinct roles for each ATPase site likely reflect a universal principle that enables these molecular machines to intricately control chromosome architecture.

Reduced levels of MRE11 cause disease phenotypes distinct from ataxia telangiectasia-like disorder.

The MRE11/RAD50/NBS1 (MRN) complex plays critical roles in cellular responses to DNA double-strand breaks. MRN is involved in end binding and processing, and it also induces cell cycle checkpoints by activating the ataxia-telangiectasia mutated (ATM) protein kinase. Hypomorphic pathogenic variants in the MRE11, RAD50, or NBS1 genes cause autosomal recessive genome instability syndromes featuring variable degrees of dwarfism, neurological defects, anemia, and cancer predisposition. Disease-associated MRN alleles include missense and nonsense variants, and many cause reduced protein levels of the entire MRN complex. However, the dramatic variability in the disease manifestation of MRN pathogenic variants is not understood. We sought to determine if low protein levels are a significant contributor to disease sequelae and therefore generated a transgenic murine model expressing MRE11 at low levels. These mice display dramatic phenotypes including small body size, severe anemia, and impaired DNA repair. We demonstrate that, distinct from ataxia telangiectasia-like disorder caused by MRE11 pathogenic missense or nonsense variants, mice and cultured cells expressing low MRE11 levels do not display the anticipated defects in ATM activation. Our findings indicate that ATM signaling can be supported by very low levels of the MRN complex and imply that defective ATM activation results from perturbation of MRN function caused by specific hypomorphic disease mutations. These distinct phenotypic outcomes underline the importance of understanding the impact of specific pathogenic MRE11 variants, which may help direct appropriate early surveillance for patients with these complicated disorders in a clinical setting.

Natural Parasite Exposure Induces Protective Human Anti-Malarial Antibodies.

Antibodies against the NANP repeat of circumsporozoite protein (CSP), the major surface antigen of Plasmodium falciparum (Pf) sporozoites, can protect from malaria in animal models but protective humoral immunity is difficult to induce in humans. Here we cloned and characterized rare affinity-matured human NANP-reactive memory B cell antibodies elicited by natural Pf exposure that potently inhibited parasite transmission and development in vivo. We unveiled the molecular details of antibody binding to two distinct protective epitopes within the NANP repeat. NANP repeat recognition was largely mediated by germline encoded and immunoglobulin (Ig) heavy-chain complementarity determining region 3 (HCDR3) residues, whereas affinity maturation contributed predominantly to stabilizing the antigen-binding site conformation. Combined, our findings illustrate the power of exploring human anti-CSP antibody responses to develop tools for malaria control in the mammalian and the mosquito vector and provide a molecular basis for the structure-based design of next-generation CSP malaria vaccines.

Endothelial Dysfunction in Youth-Onset Type 2 Diabetes: A Clinical Translational Study.

BACKGROUND: Youth-onset type 2 diabetes (Y-T2D) is associated with increased risk for coronary atherosclerotic disease, but the timing of the earliest pathological features and evidence of cardiac endothelial dysfunction have not been evaluated in this population. Magnetic resonance imaging functional imaging may detect early and direct endothelial dysfunction in the absence of classical risk factors (severe hyperglycemia, hypertension, and hyperlipidemia). Using cardiac magnetic resonance imaging functional imaging, we evaluated peripheral and coronary endothelial artery structure and function in young adults with Y-T2D diagnosed ≤5 years compared with age-matched healthy peers. We isolated and characterized plasma-derived small extracellular vesicles and evaluated their effects on inflammatory and signaling biomarkers in healthy human coronary artery endothelial cells to validate the imaging findings. METHODS: Right coronary wall thickness, coronary artery flow-mediated dilation, and brachial artery flow-mediated dilation were measured at baseline and during isometric handgrip exercise using a 3.0T magnetic resonance imaging. Human coronary artery endothelial cells were treated with Y-T2D plasma-derived small extracellular vesicles. Protein expression was measured by Western blot analysis, oxidative stress was measured using the redox-sensitive probe dihydroethidium, and nitric oxide levels were measured by 4-amino-5-methylamino-2',7'-difluororescein diacetate. RESULTS: Y-T2D (n=20) had higher hemoglobin A1c and high-sensitivity C-reactive protein, but similar total and LDL (low-density lipoprotein)-cholesterol compared with healthy peers (n=16). Y-T2D had greater coronary wall thickness (1.33±0.13 versus 1.22±0.13 mm; P=0.04) and impaired endothelial function: coronary artery flow-mediated dilation (-3.1±15.5 versus 15.9±17.3%; P<0.01) and brachial artery flow-mediated dilation (6.7±14.7 versus 26.4±15.2%; P=0.001). Y-T2D plasma-derived small extracellular vesicles reduced phosphorylated endothelial nitric oxide synthase expression and nitric oxide levels, increased reactive oxygen species production, and elevated ICAM (intercellular adhesion molecule)-mediated inflammatory pathways in human coronary artery endothelial cells. CONCLUSIONS: Coronary and brachial endothelial dysfunction was evident in Y-T2D who were within 5 years of diagnosis and did not have severe hyperglycemia or dyslipidemia. Plasma-derived small extracellular vesicles induced markers of endothelial dysfunction, which corroborated accelerated subclinical coronary atherosclerosis as an early feature in Y-T2D. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02830308.

BRD2 promotes antibody class switch recombination by facilitating DNA repair in collaboration with NIPBL.

Efficient repair of DNA double-strand breaks in the Ig heavy chain gene locus is crucial for B-cell antibody class switch recombination (CSR). The regulatory dynamics of the repair pathway direct CSR preferentially through nonhomologous end joining (NHEJ) over alternative end joining (AEJ). Here, we demonstrate that the histone acetyl reader BRD2 suppresses AEJ and aberrant recombination as well as random genomic sequence capture at the CSR junctions. BRD2 deficiency impairs switch (S) region synapse, optimal DNA damage response (DDR), and increases DNA break end resection. Unlike BRD4, a similar bromodomain protein involved in NHEJ and CSR, BRD2 loss does not elevate RPA phosphorylation and R-loop formation in the S region. As BRD2 stabilizes the cohesion loader protein NIPBL in the S regions, the loss of BRD2 or NIPBL shows comparable deregulation of S-S synapsis, DDR, and DNA repair pathway choice during CSR. This finding extends beyond CSR, as NIPBL and BRD4 have been linked to Cornelia de Lange syndrome, a developmental disorder exhibiting defective NHEJ and Ig isotype switching. The interplay between these proteins sheds light on the intricate mechanisms governing DNA repair and immune system functionality.

Neuronal activity regulates Matrin 3 abundance and function in a calcium-dependent manner through calpain-mediated cleavage and calmodulin binding.

RNA-binding protein (RBP) dysfunction is a fundamental hallmark of amyotrophic lateral sclerosis (ALS) and related neuromuscular disorders. Abnormal neuronal excitability is also a conserved feature in ALS patients and disease models, yet little is known about how activity-dependent processes regulate RBP levels and functions. Mutations in the gene encoding the RBP Matrin 3 (MATR3) cause familial disease, and MATR3 pathology has also been observed in sporadic ALS, suggesting a key role for MATR3 in disease pathogenesis. Here, we show that glutamatergic activity drives MATR3 degradation through an NMDA receptor-, Ca2+-, and calpain-dependent mechanism. The most common pathogenic MATR3 mutation renders it resistant to calpain degradation, suggesting a link between activity-dependent MATR3 regulation and disease. We also demonstrate that Ca2+ regulates MATR3 through a nondegradative process involving the binding of Ca2+/calmodulin to MATR3 and inhibition of its RNA-binding ability. These findings indicate that neuronal activity impacts both the abundance and function of MATR3, underscoring the effect of activity on RBPs and providing a foundation for further study of Ca2+-coupled regulation of RBPs implicated in ALS and related neurological diseases.

Cardioprotective properties of OMT-28, a synthetic analog of omega-3 epoxyeicosanoids.

OMT-28 is a metabolically robust small molecule developed to mimic the structure and function of omega-3 epoxyeicosanoids. However, it remained unknown to what extent OMT-28 also shares the cardioprotective and anti-inflammatory properties of its natural counterparts. To address this question, we analyzed the ability of OMT-28 to ameliorate hypoxia/reoxygenation (HR)-injury and lipopolysaccharide (LPS)-induced endotoxemia in cultured cardiomyocytes. Moreover, we investigated the potential of OMT-28 to limit functional damage and inflammasome activation in isolated perfused mouse hearts subjected to ischemia/reperfusion (IR) injury. In the HR model, OMT-28 (1 µM) treatment largely preserved cell viability (about 75 versus 40% with the vehicle) and mitochondrial function as indicated by the maintenance of NAD+/NADH-, ADP/ATP-, and respiratory control ratios. Moreover, OMT-28 blocked the HR-induced production of mitochondrial reactive oxygen species. Pharmacological inhibition experiments suggested that Gαi, PI3K, PPARα, and Sirt1 are essential components of the OMT-28-mediated pro-survival pathway. Counteracting inflammatory injury of cardiomyocytes, OMT-28 (1 µM) reduced LPS-induced increases in TNFα protein (by about 85% versus vehicle) and NF-κB DNA binding (by about 70% versus vehicle). In the ex vivo model, OMT-28 improved post-IR myocardial function recovery to reach about 40% of the baseline value compared to less than 20% with the vehicle. Furthermore, OMT-28 (1 µM) limited IR-induced NLRP3 inflammasome activation similarly to a direct NLRP3 inhibitor (MCC950). Overall, this study demonstrates that OMT-28 possesses potent cardio-protective and anti-inflammatory properties supporting the hypothesis that extending the bioavailability of omega-3 epoxyeicosanoids may improve their prospects as therapeutic agents.

Intestinal infection triggers Parkinson's disease-like symptoms in Pink1-/- mice.

Parkinson's disease is a neurodegenerative disorder with motor symptoms linked to the loss of dopaminergic neurons in the substantia nigra compacta. Although the mechanisms that trigger the loss of dopaminergic neurons are unclear, mitochondrial dysfunction and inflammation are thought to have key roles1,2. An early-onset form of Parkinson's disease is associated with mutations in the PINK1 kinase and PRKN ubiquitin ligase genes3. PINK1 and Parkin (encoded by PRKN) are involved in the clearance of damaged mitochondria in cultured cells4, but recent evidence obtained using knockout and knockin mouse models have led to contradictory results regarding the contributions of PINK1 and Parkin to mitophagy in vivo5-8. It has previously been shown that PINK1 and Parkin have a key role in adaptive immunity by repressing presentation of mitochondrial antigens9, which suggests that autoimmune mechanisms participate in the aetiology of Parkinson's disease. Here we show that intestinal infection with Gram-negative bacteria in Pink1-/- mice engages mitochondrial antigen presentation and autoimmune mechanisms that elicit the establishment of cytotoxic mitochondria-specific CD8+ T cells in the periphery and in the brain. Notably, these mice show a sharp decrease in the density of dopaminergic axonal varicosities in the striatum and are affected by motor impairment that is reversed after treatment with L-DOPA. These data support the idea that PINK1 is a repressor of the immune system, and provide a pathophysiological model in which intestinal infection acts as a triggering event in Parkinson's disease, which highlights the relevance of the gut-brain axis in the disease10.

Widespread ripples synchronize human cortical activity during sleep, waking, and memory recall.

Declarative memory encoding, consolidation, and retrieval require the integration of elements encoded in widespread cortical locations. The mechanism whereby such "binding" of different components of mental events into unified representations occurs is unknown. The "binding-by-synchrony" theory proposes that distributed encoding areas are bound by synchronous oscillations enabling enhanced communication. However, evidence for such oscillations is sparse. Brief high-frequency oscillations ("ripples") occur in the hippocampus and cortex and help organize memory recall and consolidation. Here, using intracranial recordings in humans, we report that these ∼70-ms-duration, 90-Hz ripples often couple (within ±500 ms), co-occur (≥ 25-ms overlap), and, crucially, phase-lock (have consistent phase lags) between widely distributed focal cortical locations during both sleep and waking, even between hemispheres. Cortical ripple co-occurrence is facilitated through activation across multiple sites, and phase locking increases with more cortical sites corippling. Ripples in all cortical areas co-occur with hippocampal ripples but do not phase-lock with them, further suggesting that cortico-cortical synchrony is mediated by cortico-cortical connections. Ripple phase lags vary across sleep nights, consistent with participation in different networks. During waking, we show that hippocampo-cortical and cortico-cortical coripples increase preceding successful delayed memory recall, when binding between the cue and response is essential. Ripples increase and phase-modulate unit firing, and coripples increase high-frequency correlations between areas, suggesting synchronized unit spiking facilitating information exchange. co-occurrence, phase synchrony, and high-frequency correlation are maintained with little decrement over very long distances (25 cm). Hippocampo-cortico-cortical coripples appear to possess the essential properties necessary to support binding by synchrony during memory retrieval and perhaps generally in cognition.

The Purine Biosynthesis Repressor, PurR, Contributes to Vancomycin Susceptibility of Methicillin-resistant Staphylococcus aureus in Experimental Endocarditis.

BACKGROUND: Staphylococcus aureus is the most common cause of life-threatening endovascular infections, including infective endocarditis (IE). These infections, especially when caused by methicillin-resistant strains (MRSA), feature limited therapeutic options and high morbidity and mortality rates. METHODS: Herein, we investigated the role of the purine biosynthesis repressor, PurR, in virulence factor expression and vancomycin (VAN) treatment outcomes in experimental IE due to MRSA. RESULTS: The PurR-mediated repression of purine biosynthesis was confirmed by enhanced purF expression and production of an intermediate purine metabolite in purR mutant strain. In addition, enhanced expression of the transcriptional regulators, sigB and sarA, and their key downstream virulence genes (eg, fnbA, and hla) was demonstrated in the purR mutant in vitro and within infected cardiac vegetations. Furthermore, purR deficiency enhanced fnbA/fnbB transcription, translating to increased fibronectin adhesion versus the wild type and purR-complemented strains. Notably, the purR mutant was refractory to significant reduction in target tissues MRSA burden following VAN treatment in the IE model. CONCLUSIONS: These findings suggest that the purine biosynthetic pathway intersects the coordination of virulence factor expression and in vivo persistence during VAN treatment, and may represent an avenue for novel antimicrobial development targeting MRSA.

Inhibition of cellular factor TM6SF2 suppresses secretion pathways of Hepatitis B, Hepatitis C and Hepatitis D viruses.

Chronic viral hepatitis is caused by hepatitis B virus, hepatitis C virus or hepatitis D virus (HBV, HCV, and HDV). Despite different replication strategies, all these viruses rely on secretion through the host endoplasmic reticulum-Golgi pathway, providing potential host targets for antiviral therapy. Knockdown of transmembrane 6 superfamily member 2 (TM6SF2) in virus cell culture models reduced secretion of infectious HCV virions, HDV virions and HBV subviral particles. Moreover, in a cohort of people with hepatitis B a TM6SF2 polymorphism (rs58542926 CT/TT, which causes protein misfolding and reduced TM6SF2 in the liver) correlated with lower concentrations of subviral particles in blood, complementing our previous work showing decreased HCV viral load in people with this polymorphism. In conclusion, the host protein TM6SF2 plays a key role in secretion of HBV, HCV and HDV, providing the potential for novel pan-viral agents to treat people with chronic viral hepatitis.

Utilizing genomic signatures to gain insights into the dynamics of SARS-CoV-2 through Machine and Deep Learning techniques.

The global spread of the SARS-CoV-2 pandemic, originating in Wuhan, China, has had profound consequences on both health and the economy. Traditional alignment-based phylogenetic tree methods for tracking epidemic dynamics demand substantial computational power due to the growing number of sequenced strains. Consequently, there is a pressing need for an alignment-free approach to characterize these strains and monitor the dynamics of various variants. In this work, we introduce a swift and straightforward tool named GenoSig, implemented in C++. The tool exploits the Di and Tri nucleotide frequency signatures to delineate the taxonomic lineages of SARS-CoV-2 by employing diverse machine learning (ML) and deep learning (DL) models. Our approach achieved a tenfold cross-validation accuracy of 87.88% (± 0.013) for DL and 86.37% (± 0.0009) for Random Forest (RF) model, surpassing the performance of other ML models. Validation using an additional unexposed dataset yielded comparable results. Despite variations in architectures between DL and RF, it was observed that later clades, specifically GRA, GRY, and GK, exhibited superior performance compared to earlier clades G and GH. As for the continental origin of the virus, both DL and RF models exhibited lower performance than in predicting clades. However, both models demonstrated relatively higher accuracy for Europe, North America, and South America compared to other continents, with DL outperforming RF. Both models consistently demonstrated a preference for cytosine and guanine over adenine and thymine in both clade and continental analyses, in both Di and Tri nucleotide frequencies signatures. Our findings suggest that GenoSig provides a straightforward approach to address taxonomic, epidemiological, and biological inquiries, utilizing a reductive method applicable not only to SARS-CoV-2 but also to similar research questions in an alignment-free context.

A Conversation with ChatGPT on Contentious Issues in Senescence and Cancer Research.

Artificial intelligence (AI) platforms, such as Generative Pretrained Transformer (ChatGPT), have achieved a high degree of popularity within the scientific community due to their utility in providing evidence-based reviews of the literature. However, the accuracy and reliability of the information output and the ability to provide critical analysis of the literature, especially with respect to highly controversial issues, has generally not been evaluated. In this work, we arranged a question/answer session with ChatGPT regarding several unresolved questions in the field of cancer research relating to therapy-induced senescence (TIS), including the topics of senescence reversibility, its connection to tumor dormancy, and the pharmacology of the newly emerging drug class of senolytics. ChatGPT generally provided responses consistent with the available literature, although occasionally overlooking essential components of the current understanding of the role of TIS in cancer biology and treatment. Although ChatGPT, and similar AI platforms, have utility in providing an accurate evidence-based review of the literature, their outputs should still be considered carefully, especially with respect to unresolved issues in tumor biology. SIGNIFICANCE STATEMENT: Artificial Intelligence platforms have provided great utility for researchers to investigate biomedical literature in a prompt manner. However, several issues arise when it comes to certain unresolved biological questions, especially in the cancer field. This work provided a discussion with ChatGPT regarding some of the yet-to-be-fully-elucidated conundrums of the role of therapy-induced senescence in cancer treatment and highlights the strengths and weaknesses in utilizing such platforms for analyzing the scientific literature on this topic.

Loss of muscle PDH induces lactic acidosis and adaptive anaplerotic compensation via pyruvate-alanine cycling and glutaminolysis.

Pyruvate dehydrogenase (PDH) is the rate-limiting enzyme for glucose oxidation that links glycolysis-derived pyruvate with the tricarboxylic acid (TCA) cycle. Although skeletal muscle is a significant site for glucose oxidation and is closely linked with metabolic flexibility, the importance of muscle PDH during rest and exercise has yet to be fully elucidated. Here, we demonstrate that mice with muscle-specific deletion of PDH exhibit rapid weight loss and suffer from severe lactic acidosis, ultimately leading to early mortality under low-fat diet provision. Furthermore, loss of muscle PDH induces adaptive anaplerotic compensation by increasing pyruvate-alanine cycling and glutaminolysis. Interestingly, high-fat diet supplementation effectively abolishes early mortality and rescues the overt metabolic phenotype induced by muscle PDH deficiency. Despite increased reliance on fatty acid oxidation during high-fat diet provision, loss of muscle PDH worsens exercise performance and induces lactic acidosis. These observations illustrate the importance of muscle PDH in maintaining metabolic flexibility and preventing the development of metabolic disorders.

Projected Change in the Burden of Excess Cardiovascular Deaths Associated With Extreme Heat by Midcentury (2036-2065) in the Contiguous United States.

BACKGROUND: Climate change is causing an increase in extreme heat. Individuals with cardiovascular disease are at high risk of heat-related adverse health effects. How the burden of extreme heat-associated cardiovascular deaths in the United States will change with the projected rise in extreme heat is unknown. METHODS: We obtained data on cardiovascular deaths among adults and the number of extreme heat days (maximum heat index ≥90 °F [32.2 °C]) in each county in the contiguous United States from 2008 to 2019. Based on representative concentration pathway trajectories that model greenhouse gas emissions and shared socioeconomic pathways (SSP) that model future socioeconomic scenarios and demographic projections, we obtained county-level projected numbers of extreme heat days and populations under 2 scenarios for the midcentury period 2036 to 2065: SSP2-4.5 (representing demographic projections from a "middle-of-the-road" socioeconomic scenario and an intermediate increase in emissions) and SSP5-8.5 (demographic projections in an economy based on "fossil-fueled development" and a large increase in emissions). The association of cardiovascular mortality with extreme heat was estimated with a Poisson fixed-effects model. Using estimates from this model, the projected number of excess cardiovascular deaths associated with extreme heat was calculated. RESULTS: Extreme heat was associated with 1651 (95% CI, 921-2381) excess cardiovascular deaths per year from 2008 to 2019. By midcentury, extreme heat is projected to be associated with 4320 (95% CI, 2369-6272) excess deaths annually, which is an increase of 162% (95% CI, 142-182) under SSP2-4.5, and 5491 (95% CI, 3011-7972) annual excess deaths, which is an increase of 233% (95% CI, 206-259) under SSP5-8.5. Elderly adults are projected to have a 3.5 (95% CI, 3.2-3.8) times greater increase in deaths in the SSP2-4.5 scenario compared with nonelderly adults. Non-Hispanic Black adults are projected to have a 4.6 (95% CI, 2.8-6.4) times greater increase compared with non-Hispanic White adults. The projected change in deaths was not statistically significantly different for other race and ethnicity groups or between men and women. CONCLUSIONS: By midcentury, extreme heat is projected to be associated with a significantly greater burden of excess cardiovascular deaths in the contiguous United States.