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The coordination of food intake, energy storage, and expenditure involves complex interactions between hypothalamic neurons and peripheral tissues including pancreatic islets, adipocytes, muscle, and liver. Previous research shows that deficiency of the transcription factor Alx3 alters pancreatic islet-dependent glucose homeostasis. In this study we carried out a comprehensive assessment of metabolic alterations in Alx3 deficiency. We report that Alx3-deficient mice exhibit decreased food intake without changes in body weight, along with reduced energy expenditure and altered respiratory exchange ratio. Magnetic resonance imaging reveals increased adiposity and decreased muscle mass, which was associated with markers of motor and sympathetic denervation. By contrast, Alx3-deficient mice on a high-fat diet show attenuated weight gain and improved insulin sensitivity, compared to control mice. Gene expression analysis demonstrates altered lipogenic and lipolytic gene profiles. In wild type mice Alx3 is expressed in hypothalamic arcuate nucleus neurons, but not in major peripheral metabolic organs. Functional diffusion-weighted magnetic resonance imaging reveals selective hypothalamic responses to fasting in the arcuate nucleus of Alx3-deficient mice. Additionally, altered expression of proopiomelanocortin and melanocortin-3 receptor mRNA in the hypothalamus suggests impaired regulation of feeding behavior. This study highlights the crucial role for Alx3 in governing food intake, energy homeostasis, and metabolic nutrient partitioning, thereby influencing body mass composition.
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Composição Corporal , Ingestão de Alimentos , Metabolismo Energético , Proteínas de Homeodomínio , Homeostase , Hipotálamo , Camundongos Knockout , Animais , Metabolismo Energético/genética , Hipotálamo/metabolismo , Camundongos , Ingestão de Alimentos/genética , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Dieta Hiperlipídica , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Masculino , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Pró-Opiomelanocortina/metabolismo , Pró-Opiomelanocortina/genética , Resistência à Insulina/genética , Núcleo Arqueado do Hipotálamo/metabolismoRESUMO
During pregnancy, apoptosis is a physiological event critical in the remodeling and aging of the placenta. Increasing evidence has pointed towards the relevance of hypoxia as modulator of trophoblast cell death. Previous reports have shown that leptin, a placental cytokine, promotes cell survival in both cell culture and placental explant models. The aim of this work is to establish the role of leptin in apoptosis under hypoxic condition in trophoblast cells. In this study, we evaluated the effect of cobalt chloride, a hypoxia mimicking agent that stabilizes the expression of hypoxia inducible factor-1 alpha (HIF-1α), on Swan-71 and human placental explants. Hypoxia chamber was also used to generate 2% oxygen. Apoptosis was determined by the presence of apoptotic nucleus, fragmentation of DNA and Caspase-3 and PARP-1 cleavage. The pro-apoptotic proteins BAX, BID, BAD and BAK and the anti-apoptotic effectors BCL-2, BCL-xL and MCL-1 were also analyzed. We found that HIF-1α stabilization increased the appearance of apoptotic nucleus, fragmentation of DNA, and Caspase-3 and PARP-1 cleavage. Hypoxia mimicking conditions enhanced the expression of pro-apoptotic effectors BAX, BID, BAD and BAK. HIF-1α stabilization also downregulated the level of BCL-2, BCL-xL and MCL-1. All these apoptotic parameters changes were reversed with leptin treatment. Moreover, we showed that leptin action on apoptosis modulation involves PI3K and MAPK signaling pathways. Obtained data demonstrate that HIF-1α stabilization induces apoptosis in human placenta and leptin counteracts this effect, reinforcing its role as a survival cytokine.
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Brachypodium stacei is the most ancestral lineage in the genus Brachypodium, a model system for grass functional genomics. B. stacei shows striking and sometimes contradictory biological and evolutionary features, including a high selfing rate yet extensive admixture, an ancient Miocene origin yet with recent evolutionary radiation, and adaptation to different dry climate conditions in its narrow distribution range. Therefore, it constitutes an ideal system to study these life history traits. We studied the phylogeography of 17 native circum-Mediterranean B. stacei populations (39 individuals) using genome-wide RADseq SNP data and complete plastome sequences. Nuclear SNP data revealed the existence of six distinct genetic clusters, low levels of intra-population genetic diversity and high selfing rates, albeit with signatures of admixture. Coalescence-based dating analysis detected a recent split between crown lineages in the Late Quaternary. Plastome sequences showed incongruent evolutionary relationships with those recovered by the nuclear data, suggesting interbreeding and chloroplast capture events between genetically distant populations. Demographic and population dispersal coalescent models identified an ancestral origin of B. stacei in the western-central Mediterranean islands, followed by an early colonization of the Canary Islands and two independent colonization events of the eastern Mediterranean region through long-distance dispersal and bottleneck events as the most likely evolutionary history. Climate niche data identified three arid niches of B. stacei in the southern Mediterranean region. Our findings indicate that the phylogeography of B. stacei populations was shaped by recent radiations, frequent extinctions, long-distance dispersal events, occasional interbreeding, and adaptation to local climates.
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BACKGROUND: Type 2 diabetes (T2D) patients have an increased risk of heart failure (HF). There are limited data on the association between HF and T2D in specific healthcare settings. This study sought to analyse the prevalence and incidence of HF in a contemporary cohort of T2D patients attending cardiology and endocrinology outpatient clinics. METHODS: We conducted an observational multicentre prospective study (DIABET-IC) that enrolled patients with a T2D diagnosis attending cardiology and endocrinology outpatient clinics in 30 centres in Spain between 2018 and 2019. The prevalence at the start of the study and the incidence of HF after a 3 year follow-up were calculated. HF was defined as the presence of typical symptoms and either: a) LVEF < 40%; or b) LVEF ≥ 40% with elevated natriuretic peptides and echocardiographic abnormalities. RESULTS: A total of 1249 T2D patients were included in the present analysis (67.6 ± 10.1 years, 31.7% female). HF was present in 490 participants at baseline (prevalence 39.2%), 150 (30.6%) of whom had a preserved ejection fraction. The presence of adverse social determinants and chronic conditions such as chronic kidney disease and atherosclerotic cardiovascular disease were more frequent in HF patients. During the study period, there were 58 new diagnoses of HF (incidence 7.6%) among those without baseline HF. The incidence rate was 3.0 per 100 person-years. Independent predictors of incident HF were smoking, left ventricular ejection fraction, NT-ProBNP, history of tachyarrhythmia and treatment with pioglitazone, oral anticoagulants, or diuretics. Despite an average suboptimal glycaemic control, the use of antidiabetic drugs with cardiovascular benefits was low (30.4% for sodium-glucose cotransporter-2 inhibitors and 12.5% for glucagon-like peptide-1 receptor agonists). CONCLUSIONS: In this contemporary cohort of T2D patients attending cardiology and endocrinology outpatient clinics, the prevalence and incidence of HF were high, comorbidities were frequent, and the use of antidiabetic agents with cardiovascular benefit was low. Outpatient care seems to be a unique opportunity for a comprehensive T2D approach that encompasses HF prevention, diagnosis, and treatment.
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Diabetes Mellitus Tipo 2 , Insuficiência Cardíaca , Humanos , Diabetes Mellitus Tipo 2/epidemiologia , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/sangue , Feminino , Masculino , Estudos Prospectivos , Incidência , Insuficiência Cardíaca/epidemiologia , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/fisiopatologia , Prevalência , Pessoa de Meia-Idade , Espanha/epidemiologia , Idoso , Fatores de Tempo , Medição de Risco , Fatores de Risco , Prognóstico , Função Ventricular Esquerda , Hipoglicemiantes/uso terapêuticoRESUMO
The burden of cardiovascular disease is particularly high among individuals with diabetes, even when LDL cholesterol is normal or within the therapeutic target. Despite this, cholesterol accumulates in their arteries, in part, due to persistent atherogenic dyslipidaemia characterized by elevated triglycerides, remnant cholesterol, smaller LDL particles and reduced HDL cholesterol. The causal link between dyslipidaemia and atherosclerosis in T2DM is complex, and our contention is that a deeper understanding of lipoprotein composition and functionality, the vehicle that delivers cholesterol to the artery, will provide insight for improving our understanding of the hidden cardiovascular risk of diabetes. This narrative review covers three levels of complexity in lipoprotein characterization: 1-the information provided by routine clinical biochemistry, 2-advanced nuclear magnetic resonance (NMR)-based lipoprotein profiling and 3-the identification of minor components or physical properties of lipoproteins that can help explain arterial accumulation in individuals with normal LDLc levels, which is typically the case in individuals with T2DM. This document highlights the importance of incorporating these three layers of lipoprotein-related information into population-based studies on ASCVD in T2DM. Such an attempt should inevitably run in parallel with biotechnological solutions that allow large-scale determination of these sets of methodologically diverse parameters.
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Doenças Cardiovasculares , Diabetes Mellitus Tipo 2 , Fatores de Risco de Doenças Cardíacas , Lipoproteínas , Humanos , Diabetes Mellitus Tipo 2/complicações , Lipoproteínas/metabolismo , Lipoproteínas/sangue , Doenças Cardiovasculares/etiologia , Dislipidemias , Espectroscopia de Ressonância Magnética , Aterosclerose , LDL-Colesterol/metabolismo , LDL-Colesterol/sangue , HDL-Colesterol/metabolismo , Triglicerídeos/metabolismoRESUMO
2,5-Dimethyl-2,4-hexadiene is a readily available and easily managable compound, whose symmetric and polymethylated dienic structure should be prone to engage in cross-metathesis reactions with other alkenes, but this has not been apparently exploited so far. Here we show that this reactant enables the easy synthesis of tri- and tetra-susbtituted alkenes (i. e. isobutylenyl and prenyl groups) from simple alkenes under mild reaction conditions, not only with the conventional 2nd generation Grubbs catalyst but also with other Grela-type catalyts such as StickyCat,TM AquaMetTM and GreenCatTM. The use of liquid and low volatile 2,5-dimethyl-2,4-hexadiene avoids the use of gaseous alkene reactants and, besides, showcases the reactivity of polyisoprene (rubber), thus allowing to optimize the reaction conditions for rubber upcycling, after metathesis reaction of the pristine or used polymer with simple alkenes. These results bring low volatile isoprene-type compounds as privileged poly-substituted reactants for alkene cross-metathesis reactions.
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BACKGROUND: Obesity-related comorbidities may relapse in patients with weight regain after bariatric surgery. However, HDL cholesterol (HDLc) levels increase after surgery and seem to remain stable despite a gradual increase in BMI. The aim of this study is to analyze the effects of weight regain after bariatric surgery on HDL cholesterol. MATERIALS AND METHODS: This is a retrospective, observational, cohort study in patients who underwent bariatric surgery in the Hospital de la Santa Creu i Sant Pau (Barcelona) between 2007 and 2015. Patients without at least 5 years of follow-up after surgery, under fibrate treatment, and those who required revisional surgery were excluded from the analysis. Data were collected at baseline, 3 and 6 months after surgery, and then annually until 5 years post-surgery. RESULTS: One hundred fifty patients were analyzed. 93.3% of patients reached > 20% of total weight loss after surgery. At 5th year, 37% of patients had regained > 15% of nadir weight, 60% had regained > 10%, and 22% had regained < 5% of nadir weight. No differences were found in HDLc levels between the different groups of weight regain, nor in the % of change in HDLc levels between nadir weight and 5 years, or in the proportion of patients with normal HDLc concentrations either. CONCLUSION: HDLc remains stable regardless of weight regain after bariatric surgery.
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Cirurgia Bariátrica , HDL-Colesterol , Aumento de Peso , Redução de Peso , Humanos , Estudos Retrospectivos , Feminino , Masculino , HDL-Colesterol/sangue , Adulto , Pessoa de Meia-Idade , Obesidade Mórbida/cirurgia , Obesidade Mórbida/sangue , Índice de Massa Corporal , RecidivaRESUMO
PURPOSE: To evaluate the outcomes of adding arthroscopy to osteosynthesis of distal radius fractures (DRF) with volar locking plate (VLP), by Patient-Rated Wrist Evaluation (PRWE) 1 year after surgery. METHODS: In total, 186 functionally independent adult patients who met the inclusion criteria (DRF and a clinical decision for surgery with a VLP) were randomized to arthroscopic assistance or not. Primary outcome was PRWE questionnaire results 1 year after surgery. For the main variable, PRWE, we obtained the minimal clinically important difference based on a distribution-based method. Secondary outcomes included Disabilities of the Arm, Shoulder and Hand and 12-Item Short Form Health Survey questionnaires, range of motion, strength, radiographic measures, and presence of joint step-offs by computed tomography. Data were collected preoperatively and at +1 and +4 weeks, +3 and +6 months, and +1 year after surgery. Complications were recorded throughout the study. RESULTS: In total, 180 patients (mean age: 59.0 ± 14.9 years; 76% women) were analyzed by modified intention to treat. A total of 82% of the fractures were intra-articular (AO type C). No significant difference between arthroscopic (AG) and control (CG) groups in median PRWE was found at +1 year (median AG: 5.0, median CG: 7.5, difference in medians 2.5; 95% confidence interval [CI] -2.0, 7.0, P = .328). The proportion of patients who exceeded the minimal clinically important difference of 12.81 points in the AG and CG was 86.4% vs 85.1%, P = .819, respectively. Percentage of associated injuries and step-offs reduction maneuvers was greater with arthroscopy (mean differences: 17.1 95% CI -0.1, 26.1, P < .001) and 17.4 (95% CI 5.0, 29.7, P = .007). The difference in percentage of residual joint step-offs at the postsurgical computed tomography in radioulnar, radioscaphoid, and radiolunate joints was not significant (P = .990, P = .538, and P = .063). Complications were similar between groups (16.9% vs 20.9%, P = .842). CONCLUSIONS: Adjuvant arthroscopy did not significantly improve PRWE score +1 year after surgery for DRF with VLP, although the statistical power of the study is below the initially estimated to detect the expected difference. LEVEL OF EVIDENCE: Level I, randomized controlled trial.
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Fraturas do Rádio , Fraturas do Punho , Adulto , Humanos , Feminino , Pessoa de Meia-Idade , Idoso , Masculino , Resultado do Tratamento , Artroscopia , Fraturas do Rádio/cirurgia , Fraturas do Rádio/diagnóstico , Fixação Interna de Fraturas/métodos , Placas Ósseas , Amplitude de Movimento ArticularRESUMO
Inflammatory diseases are strongly associated with global morbidity and mortality. Several mediators are involved in this process, including proinflammatory interleukins and cytokines produced by damaged tissues that, somehow, act as initiators of the autoreactive immune response. Bioactive compounds present in plant-based foods and byproducts have been largely considered active agents with the potential to treat or prevent inflammatory diseases, being a valuable alternative to traditional therapeutic agents used nowadays, which present several side effects. In this regard, the present research uncovers the anti-inflammatory activity of the bioaccessible fraction of broccoli stalks processed, by applying different conditions that render specific concentrations of bioactive sulforaphane (SFN). The raw materials' extracts exhibited significantly different contents of total glucosinolates (GSLs) that ranged between 3993.29 and 12,296.48 mg/kg dry weight (dw), with glucoraphanin as the most abundant one, followed by GI and GE. The indolic GSLs were represented by hydroxy-glucobrassicin, glucobrassicin, methoxy-glucobrassicin, and neo-glucobrassicin, with the two latter as the most abundant. Additionally, SFN and indole-3-carbinol were found in lower concentrations than the corresponding GSL precursors in the raw materials. When exploring the bioaccessibility of these organosulfur compounds, the GSL of all matrices remained at levels lower than the limit of detection, while SFN was the only breakdown product that remained stable and at quantifiable concentrations. The highest concentration of bioaccessible SFN was provided by the high-ITC materials (~4.00 mg/kg dw). The results retrieved on the cytotoxicity of the referred extracts evidenced that the range of supplementation of growth media tested (0.002-430.400 µg of organosulfur compounds/mL) did not display cytotoxic effects on Caco-2 cells. The obtained extracts were assessed based on their capacity to reduce the production of key proinflammatory cytokines (interleukin 6 (IL-6), IL-8, and TNF-α) by the intestinal epithelium. Most of the tested processing conditions provided plant material with significant anti-inflammatory activity and the absence of cytotoxic effects. These data confirm that SFN from broccoli stalks, processed to optimize the bioaccessible concentration of SFN, may be potential therapeutic leads to treat or prevent human intestinal inflammation.
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Brassica , Glucosinolatos , Indóis , Doenças Inflamatórias Intestinais , Isotiocianatos , Sulfóxidos , Humanos , Células CACO-2 , Doenças Inflamatórias Intestinais/tratamento farmacológico , Citocinas , Mediadores da Inflamação , Anti-Inflamatórios/farmacologiaRESUMO
Diabetes mellitus (DM) is a highly prevalent disease worldwide, estimated to affect 1 in every 11 adults; among them, 90-95% of cases are type 2 diabetes mellitus. This is partly attributed to the surge in the prevalence of obesity, which has reached epidemic proportions since 2008. In these patients, cardiovascular (CV) risk stands as the primary cause of morbidity and mortality, placing a substantial burden on healthcare systems due to the potential for macrovascular and microvascular complications. In this context, leptin, an adipocyte-derived hormone, plays a fundamental role. This hormone is essential for regulating the cellular metabolism and energy balance, controlling inflammatory responses, and maintaining CV system homeostasis. Thus, leptin resistance not only contributes to weight gain but may also lead to increased cardiac inflammation, greater fibrosis, hypertension, and impairment of the cardiac metabolism. Understanding the relationship between leptin resistance and CV risk in obese individuals with type 2 DM (T2DM) could improve the management and prevention of this complication. Therefore, in this narrative review, we will discuss the evidence linking leptin with the presence, severity, and/or prognosis of obesity and T2DM regarding CV disease, aiming to shed light on the potential implications for better management and preventive strategies.
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Doenças Cardiovasculares , Diabetes Mellitus Tipo 2 , Leptina , Obesidade , Adulto , Humanos , Doenças Cardiovasculares/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Leptina/metabolismo , Obesidade/metabolismoRESUMO
The dental implant surface plays a crucial role in osseointegration. The topography and physicochemical properties will affect the cellular functions. In this research, four distinct titanium surfaces have been studied: machined acting (MACH), acid etched (AE), grit blasting (GBLAST), and a combination of grit blasting and subsequent acid etching (GBLAST + AE). Human amniotic mesenchymal (hAMSCs) and epithelial stem cells (hAECs) isolated from the amniotic membrane have attractive stem-cell properties. They were cultured on titanium surfaces to analyze their impact on biological behavior. The surface roughness, microhardness, wettability, and surface energy were analyzed using interferometric microscopy, Vickers indentation, and drop-sessile techniques. The GBLAST and GBLAST + AE surfaces showed higher roughness, reduced hydrophilicity, and lower surface energy with significant differences. Increased microhardness values for GBLAST and GBLAST + AE implants were attributed to surface compression. Cell viability was higher for hAMSCs, particularly on GBLAST and GBLAST + AE surfaces. Alkaline phosphatase activity enhanced in hAMSCs cultured on GBLAST and GBLAST + AE surfaces, while hAECs showed no mineralization signals. Osteogenic gene expression was upregulated in hAMSCs on GBLAST surfaces. Moreover, α2 and ß1 integrin expression enhanced in hAMSCs, suggesting a surface-integrin interaction. Consequently, hAMSCs would tend toward osteoblastic differentiation on grit-blasted surfaces conducive to osseointegration, a phenomenon not observed in hAECs.
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Âmnio , Implantes Dentários , Propriedades de Superfície , Titânio , Humanos , Titânio/química , Âmnio/citologia , Âmnio/metabolismo , Osteogênese , Diferenciação Celular , Células Cultivadas , Osseointegração , Células-Tronco/citologia , Células-Tronco/metabolismo , Células-Tronco Mesenquimais/metabolismo , Células-Tronco Mesenquimais/citologia , Sobrevivência Celular , Fosfatase Alcalina/metabolismoRESUMO
The prevalence of overweight and obesity, and, consequently, associated comorbidities, is increasing significantly worldwide. The guidelines recommend a percentage of weight loss> 5% to achieve beneficial effects on metabolic comorbidities associated with obesity. Furthermore, greater weight losses (> 10%) produce more significant improvements, and may even produce remission of some of these comorbidities. In this chapter, we review the evidence of the effect of weight loss through different strategies (lifestyle intervention, pharmacological treatment, or bariatric surgery) on the main cardiometabolic pathologies associated with excess adipose tissue (type 2 diabetes, high blood pressure, dyslipidemia, metabolic dysfunction-associated steatotic liver disease, inflammation, cardiovascular diseases, and mortality).
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Obesity is a major global public health issue involving dyslipidemia, oxidative stress, inflammation, and increased risk of CVD. Weight loss reduces this risk, but the biochemical underpinnings are unclear. We explored how obesity and weight loss after bariatric surgery influence LDL interactions that trigger proatherogenic versus antiatherogenic processes. LDL was isolated from plasma of six patients with severe obesity before (basal) and 6-12 months after bariatric surgery (basal BMI = 42.7 kg/m2; 6-months and 12-months postoperative BMI = 34.1 and 30 kg/m2). Control LDL were from six healthy subjects (BMI = 22.6 kg/m2). LDL binding was quantified by ELISA; LDL size and charge were assessed by chromatography; LDL biochemical composition was determined. Compared to controls, basal LDL showed decreased nonatherogenic binding to LDL receptor, which improved postoperatively. Conversely, basal LDL showed increased binding to scavenger receptors LOX1 and CD36 and to glycosaminoglycans, fibronectin and collagen, which is proatherogenic. One year postoperatively, this binding decreased but remained elevated, consistent with elevated lipid peroxidation. Serum amyloid A and nonesterified fatty acids were elevated in basal and postoperative LDL, indicating obesity-associated inflammation. Aggregated and electronegative LDL remained elevated, suggesting proatherogenic processes. These results suggest that obesity-induced inflammation contributes to harmful LDL alterations that probably increase the risk of CVD. We conclude that in obesity, LDL interactions with cell receptors and extracellular matrix shift in a proatherogenic manner but are partially reversed upon postoperative weight loss. These results help explain why the risk of CVD increases in obesity but decreases upon weight loss.
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Cirurgia Bariátrica , Doenças Cardiovasculares , Humanos , Receptores de LDL/metabolismo , Obesidade/cirurgia , Inflamação , Matriz Extracelular/metabolismo , Redução de Peso , Lipoproteínas LDL/metabolismoRESUMO
Commercially available zeolite Y modulates the catalytic activity and selectivity of ultrasmall silver species during the Buchner reaction and the carbene addition to methylene and hydroxyl bonds, by simply exchanging the counter cations of the zeolite framework. The zeolite acts as a macroligand to tune the silver catalytic site, enabling the use of this cheap and recyclable solid catalyst for the in situ formation of carbenes from diazoacetate and selective insertion in different C-H (i.e., cyclohexane) and C-O (i.e., water) bonds. The amount of catalyst in the reaction can be as low as ≤0.1 mol % silver. Besides, this reactivity allows deeply drying the HY zeolite framework by making the strongly adsorbed water molecules react with the in situ formed carbenes.
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The combination of well-defined Fe3+ isolated single-metal atoms and Ag2 subnanometer metal clusters within the channels of a metal-organic framework (MOF) is reported and characterized by single-crystal X-ray diffraction for the first time. The resulting hybrid material, with the formula [Ag02(Ag0)1.34FeIII0.66]@NaI2{NiII4[CuII2(Me3mpba)2]3}·63H2O (Fe3+Ag02@MOF), is capable of catalyzing the unprecedented direct conversion of styrene to phenylacetylene in one pot. In particular, Fe3+Ag02@MOFâwhich can easily be obtained in a gram scaleâexhibits superior catalytic activity for the TEMPO-free oxidative cross-coupling of styrenes with phenyl sulfone to give vinyl sulfones in yields up to >99%, which are ultimately transformed, in situ, to the corresponding phenylacetylene product. The results presented here constitute a paradigmatic example of how the synthesis of different metal species in well-defined solid catalysts, combined with speciation of the true metal catalyst of an organic reaction in solution, allows the design of a new challenging reaction.
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High-quality devices based on layered heterostructures are typically built from materials obtained by complex solid-state physical approaches or laborious mechanical exfoliation and transfer. Meanwhile, wet-chemically synthesized materials commonly suffer from surface residuals and intrinsic defects. Here, we synthesize using an unprecedented colloidal photocatalyzed, one-pot redox reaction a few-layers bismuth hybrid of "electronic grade" structural quality. Intriguingly, the material presents a sulfur-alkyl-functionalized reconstructed surface that prevents it from oxidation and leads to a tuned electronic structure that results from the altered arrangement of the surface. The metallic behavior of the hybrid is supported by ab initio predictions and room temperature transport measurements of individual nanoflakes. Our findings indicate how surface reconstructions in two-dimensional (2D) systems can promote unexpected properties that can pave the way to new functionalities and devices. Moreover, this scalable synthetic process opens new avenues for applications in plasmonics or electronic (and spintronic) device fabrication. Beyond electronics, this 2D hybrid material may be of interest in organic catalysis, biomedicine, or energy storage and conversion.
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Invited for the cover of this issue are Jesús Ferrando-Soria, Donatella Armentano, Antonio Leyva-Pérez, Emilio Pardo and co-workers at University of Valencia, Technical University of Valencia and University of Calabria. The image depicts the crystal structure of a novel ZnII biological metal-organic framework that mimics ß-lactamase enzymes. Read the full text of the article at 10.1002/chem.202301325.
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Biomimética , Estruturas Metalorgânicas , Humanos , Catálise , Penicilinas , beta-Lactamases , Antibacterianos , ZincoRESUMO
ß-Lactam antibiotics are one of the most commonly prescribed drugs to treat bacterial infections. However, their use has been somehow limited given the emergence of bacteria with resistance mechanisms, such as ß-lactamases, which inactivate them by degrading their four-membered ß-lactam rings. So, a total knowledge of the mechanisms governing the catalytic activity of ß-lactamases is required. Here, we report a novel Zn-based metal-organic framework (MOF, 1), possessing functional channels capable to accommodate and interact with antibiotics, which catalyze the selective hydrolysis of the penicillinic antibiotics amoxicillin and ceftriaxone. In particular, MOF 1 degrades, very efficiently, the four-membered ß-lactam ring of amoxicillin, acting as a ß-lactamase mimic, and expands the very limited number of MOFs capable to mimic catalytic enzymatic processes. Combined single-crystal X-ray diffraction (SCXRD) studies and density functional (DFT) calculations offer unique snapshots on the host-guest interactions established between amoxicillin and the functional channels of 1. This allows to propose a degradation mechanism based on the activation of a water molecule, promoted by a Zn-bridging hydroxyl group, concertedly to the nucleophilic attack to the carbonyl moiety and the cleaving of C-N bond of the lactam ring.
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Estruturas Metalorgânicas , beta-Lactamases , beta-Lactamases/química , Penicilinas , Biomimética , Antibacterianos/química , beta-Lactamas , Catálise , Amoxicilina , Zinco/químicaRESUMO
The synthesis of cis-alkenes is industrially carried out by selective semi-hydrogenation of alkynes with complex Pd catalysts, which include the Lindlar catalyst (PdPb on CaCO3) and c-Pd/TiS (colloidal ligand-protected Pd nanoparticles), among others. Here, we show that Pd0 atoms are generated from primary Pd salts (PdCl2, PdSO4, Pd(OH)2, PdO) with H2 in alcohol solutions, independently of the alkyne, to catalyze the semi-hydrogenation reaction with extraordinarily high efficiency (up to 735 s-1), yield (up to 99%), and selectivity (up to 99%). The easy-to-prepare Pd0 species hold other potential catalytic applications.
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The fragrance compound indomuscone is used here as a scaffold to prepare two different sterically hindered phosphines, one aromatic and another alkylic, in good yields, after four synthetic steps. The new phosphines show enhanced electronic and steric properties when compared to benchmark commercial phosphine ligands, which is reflected in the catalytic results obtained for representative palladium-catalyzed reactions such as the telomerization reaction, the Buchwald-Hartwig and Suzuki cross-coupling reactions of chloroaromatic rings, and the semi-hydrogenation reaction of an alkyne. In particular, the indomuscone-based aromatic phosphine ligand leads to the highest selectivity for the tail-to-head telomerization product between isoprene and methanol, while the indomuscone-based alkylic phosphine ligand shows extraordinary similarities with the Buchwald-type SPhos phosphine ligand.