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1.
PLoS Biol ; 20(12): e3001938, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36542658

RESUMO

Sustained attention (SA) and working memory (WM) are critical processes, but the brain networks supporting these abilities in development are unknown. We characterized the functional brain architecture of SA and WM in 9- to 11-year-old children and adults. First, we found that adult network predictors of SA generalized to predict individual differences and fluctuations in SA in youth. A WM model predicted WM performance both across and within children-and captured individual differences in later recognition memory-but underperformed in youth relative to adults. We next characterized functional connections differentially related to SA and WM in youth compared to adults. Results revealed 2 network configurations: a dominant architecture predicting performance in both age groups and a secondary architecture, more prominent for WM than SA, predicting performance in each age group differently. Thus, functional connectivity (FC) predicts SA and WM in youth, with networks predicting WM performance differing more between youths and adults than those predicting SA.


Assuntos
Imageamento por Ressonância Magnética , Memória de Curto Prazo , Criança , Adulto , Adolescente , Humanos , Imageamento por Ressonância Magnética/métodos , Encéfalo , Atenção , Mapeamento Encefálico/métodos
2.
J Physiol ; 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38411283

RESUMO

We measured the impact of blood flow restriction on muscle protein synthesis rates, muscle mass and strength during 2 weeks of strict bed rest. Twelve healthy, male adults (age: 24 ± 3 years, body mass index: 23.7 ± 3.1 kg/m2 ) were subjected to 14 days of strict bed rest with unilateral blood flow restriction performed three times daily in three 5 min cycles (200 mmHg). Participants consumed deuterium oxide and we collected blood and saliva samples throughout 2 weeks of bed rest. Before and immediately after bed rest, lean body mass (dual-energy X-ray absorptiometry scan) and thigh muscle volume (magnetic resonance imaging scan) were assessed in both the blood flow restricted (BFR) and control (CON) leg. Muscle biopsies were collected and unilateral muscle strength (one-repetition maximum; 1RM) was assessed for both legs before and after the bed rest period. Bed rest resulted in 1.8 ± 1.0 kg lean body mass loss (P < 0.001). Thigh muscle volume declined from 7.1 ± 1.1 to 6.7 ± 1.0 L in CON and from 7.0 ± 1.1 to 6.7 ± 1.0 L in BFR (P < 0.001), with no differences between treatments (P = 0.497). In addition, 1RM leg extension strength decreased from 60.2 ± 10.6 to 54.8 ± 10.9 kg in CON and from 59.2 ± 12.1 to 52.9 ± 12.0 kg in BFR (P = 0.014), with no differences between treatments (P = 0.594). Muscle protein synthesis rates during bed rest did not differ between the BFR and CON leg (1.11 ± 0.12 vs. 1.08 ± 0.13%/day, respectively; P = 0.302). Two weeks of bed rest substantially reduces skeletal muscle mass and strength. Blood flow restriction during bed rest does not modulate daily muscle protein synthesis rates and does not preserve muscle mass or strength. KEY POINTS: Bed rest, often necessary for recovery from illness or injury, leads to the loss of muscle mass and strength. It has been postulated that blood flow restriction may attenuate the loss of muscle mass and strength during bed rest. We investigated the effect of blood flow restriction on muscle protein synthesis rates, muscle mass and strength during 2 weeks of strict bed rest. Blood flow restriction applied during bed rest does not modulate daily muscle protein synthesis rates and does not preserve muscle mass or strength. Blood flow restriction is not effective in preventing muscle atrophy during a prolonged period of bed rest.

3.
Pflugers Arch ; 476(4): 427-443, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38282081

RESUMO

Maintaining an appropriate acid-base equilibrium is crucial for human health. A primary influencer of this equilibrium is diet, as foods are metabolized into non-volatile acids or bases. Dietary acid load (DAL) is a measure of the acid load derived from diet, taking into account both the potential renal acid load (PRAL) from food components like protein, potassium, phosphorus, calcium, and magnesium, and the organic acids from foods, which are metabolized to bicarbonate and thus have an alkalinizing effect. Current Western diets are characterized by a high DAL, due to large amounts of animal protein and processed foods. A chronic low-grade metabolic acidosis can occur following a Western diet and is associated with increased morbidity and mortality. Nutritional advice focusing on DAL, rather than macronutrients, is gaining rapid attention as it provides a more holistic approach to managing health. However, current evidence for the role of DAL is mainly associative, and underlying mechanisms are poorly understood. This review focusses on the role of DAL in multiple conditions such as obesity, cardiovascular health, impaired kidney function, and cancer.


Assuntos
Acidose , Dieta , Animais , Humanos , Equilíbrio Ácido-Base , Rim/metabolismo , Acidose/metabolismo , Obesidade/metabolismo
4.
Ecol Lett ; 27(1): e14372, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38288868

RESUMO

The onset of global climate change has led to abnormal rainfall patterns, disrupting associations between wildlife and their symbiotic microorganisms. We monitored a population of pumpkin toadlets and their skin bacteria in the Brazilian Atlantic Forest during a drought. Given the recognized ability of some amphibian skin bacteria to inhibit the widespread fungal pathogen Batrachochytrium dendrobatidis (Bd), we investigated links between skin microbiome health, susceptibility to Bd and host mortality during a die-off event. We found that rainfall deficit was an indirect predictor of Bd loads through microbiome disruption, while its direct effect on Bd was weak. The microbiome was characterized by fewer putative Bd-inhibitory bacteria following the drought, which points to a one-month lagged effect of drought on the microbiome that may have increased toadlet susceptibility to Bd. Our study underscores the capacity of rainfall variability to disturb complex host-microbiome interactions and alter wildlife disease dynamics.


Assuntos
Quitridiomicetos , Microbiota , Micoses , Animais , Secas , Micoses/veterinária , Anfíbios/microbiologia , Bactérias , Animais Selvagens , Pele/microbiologia
5.
Ecol Lett ; 27(9): e14499, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39354894

RESUMO

Shelter-building insects are important ecosystem engineers, playing critical roles in structuring arthropod communities. Nonetheless, the influence of leaf shelters and arthropods on plant-associated microbiota remains largely unexplored. Arthropods that visit or inhabit plants can contribute to the leaf microbial community, resulting in significant changes in plant-microbe interactions. By artificially constructing leaf shelters, we provide evidence that shelter-building insects influence not only the arthropod community structure but also impact the phyllosphere microbiota. Leaf shelters exhibited higher abundance and richness of arthropods, changing the associated arthropod community composition. These shelters also altered the composition and community structure of phyllosphere microbiota, promoting greater richness and diversity of bacteria at the phyllosphere. In leaf shelters, microbial diversity positively correlated with the richness and diversity of herbivores. These findings demonstrate the critical role of leaf shelters in structuring both arthropod and microbial communities through altered microhabitats and species interactions.


Assuntos
Artrópodes , Biodiversidade , Microbiota , Folhas de Planta , Animais , Folhas de Planta/microbiologia , Artrópodes/microbiologia , Bactérias/classificação , Bactérias/genética , Ecossistema , Herbivoria
6.
Anal Chem ; 96(23): 9693-9703, 2024 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-38815160

RESUMO

Specific amino acid footprinting mass spectrometry (MS) is an increasingly utilized method for elucidating protein higher order structure (HOS). It does this by adding to certain amino acid residues a mass tag, whose reaction extent depends on solvent accessibility and microenvironment of the protein. Unlike reactive free radicals and carbenes, these specific footprinters react slower than protein unfolding. Thus, their footprinting, under certain conditions, provokes structural changes to the protein, leading to labeling on non-native structures. It is critical to establish conditions (i.e., reagent concentrations, time of reaction) to ensure that the structure of the protein following footprinting remains native. Here, we compare the efficacy of five methods in assessing protein HOS following footprinting at the intact protein level and then further localize the perturbation at the peptide level. Three are MS-based methods that provide dose-response plot analysis, evaluation of Poisson distributions of precursor and products, and determination of the average number of modifications. These MS-based methods reliably and effectively indicate HOS perturbation at the intact protein level, whereas spectroscopic methods (circular dichroism (CD) and dynamic light scattering (DLS)) are less sensitive in monitoring subtle HOS perturbation caused by footprinting. Evaluation of HOS at the peptide level indicates regions that are sensitive to localized perturbations. Peptide-level analysis also provides higher resolution of the HOS perturbation, and we recommend using it for future footprinting studies. Overall, this work shows conclusive evidence for HOS perturbation caused by footprinting. Implementation of quality control workflows can identify conditions to avoid the perturbation, for footprinting, allowing accurate and reliable identification of protein structural changes that accompany, for example, ligand interactions, mutations, and changes in solution environment.


Assuntos
Proteínas , Proteínas/química , Espectrometria de Massas , Pegadas de Proteínas/métodos , Conformação Proteica , Aminoácidos/química , Dicroísmo Circular
7.
Opt Express ; 32(5): 7053-7063, 2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38439396

RESUMO

In the process of multi-pulse laser ablation, inter-pulse delay time, Δt, is known to be an important parameter for maximizing ablation efficiency as well as impulse imparted to the target. In this work, using photon Doppler velocimetry, we show that for single pairs of colinear pulses (1064 nm, 8 ns, ∼ 60 J cm-2 per pulse) in air, the peak free surface velocity of the back surface of an aluminum target (125 µm thick) is increased, by a factor of nearly 3, when Δt = 10 microseconds, compared with both pulses arriving simultaneously (Δt = 0). Fast imaging of the ablation process suggests this enhancement is due to rarefaction of the contiguous air in the passage of the leading shock produced by ablation, which then in turn allows a larger fraction of the energy of the second pulse to reach the target surface. This interpretation is strengthened by additional experiments in which the two pulses do not overlap on the target surface, but the shock strength is nevertheless enhanced. Given a fixed energy budget this work suggests a prescription for maximizing laser-driven shock strength by judicious choice of inter-pulse delay.

8.
J Org Chem ; 89(13): 9405-9419, 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38865165

RESUMO

A new method for the preparation of the underrepresented 1,5-dimethyl-6-thioverdazyl radicals has been developed employing Lawesson's reagent (LR). The synthetic route involves the direct thionation of the carbonyl group of the corresponding dialkylbishydrazone followed by cyclization to give the tetrazinanthione verdazyl precursor on a gram scale. Subsequent oxidation yields the 6-thioverdazyl radical. It was determined that thionation of substrates containing electron-withdrawing groups in the ortho- or para-positions was high yielding. In contrast, for the parent phenyl group or substrates bearing weakly electron-donating substituents, thionation efficiency was significantly reduced. This could be overcome by utilizing partial in situ cyclization, which occurs during work up, to generate the tetrazinanthione directly via a one-pot synthesis. Density functional theory suggests that the LR fragment interacts with the carbonyl prior to cycloaddition and subsequent to cycloreversion, leading to the thiocarbonyl. The electronic nature of the radical is characterized with electron paramagnetic resonance as well as the first report of 6-thioverdazyl redox properties.

9.
Transpl Int ; 37: 13218, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39100754

RESUMO

Delayed graft function (DGF) after kidney transplantation heralds a worse prognosis. In patients with hyperoxaluria, the incidence of DGF is high. Oxalic acid is a waste product that accumulates when kidney function decreases. We hypothesize that residual diuresis and accumulated waste products influence the DGF incidence. Patients transplanted between 2018-2022 participated in the prospective cohort study. Pre-transplant concentrations of oxalic acid and its precursors were determined. Data on residual diuresis and other recipient, donor or transplant related variables were collected. 496 patients were included, 154 were not on dialysis. Oxalic acid, and glyoxylic acid, were above upper normal concentrations in 98.8%, and 100% of patients. Residual diuresis was ≤150 mL/min in 24% of patients. DGF occurred in 157 patients. Multivariable binary logistic regression analysis demonstrated a significant influence of dialysis type, recipient BMI, donor type, age, and serum creatinine on the DGF risk. Residual diuresis and glycolic acid concentration were inversely proportionally related to this risk, glyoxylic acid directly proportionally. Results in the dialysis population showed the same results, but glyoxylic acid lacked significance. In conclusion, low residual diuresis is associated with increased DGF incidence. Possibly accumulated waste products also play a role. Pre-emptive transplantation may decrease the incidence of DGF.


Assuntos
Função Retardada do Enxerto , Diurese , Glioxilatos , Transplante de Rim , Ácido Oxálico , Humanos , Transplante de Rim/efeitos adversos , Feminino , Masculino , Pessoa de Meia-Idade , Função Retardada do Enxerto/etiologia , Função Retardada do Enxerto/epidemiologia , Adulto , Estudos Prospectivos , Idoso , Diálise Renal , Glicolatos , Hiperoxalúria/etiologia , Fatores de Risco , Incidência
10.
Dev Psychopathol ; : 1-13, 2024 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-39324228

RESUMO

BACKGROUND: Reward and threat processes work together to support adaptive learning during development. Adolescence is associated with increasing approach behavior (e.g., novelty-seeking, risk-taking) but often also coincides with emerging internalizing symptoms, which are characterized by heightened avoidance behavior. Peaking engagement of the nucleus accumbens (NAcc) during adolescence, often studied in reward paradigms, may also relate to threat mechanisms of adolescent psychopathology. METHODS: 47 typically developing adolescents (9.9-22.9 years) completed an aversive learning task during functional magnetic resonance imaging, wherein visual cues were paired with an aversive sound or no sound. Task blocks involved an escapable aversively reinforced stimulus (CS+r), the same stimulus without reinforcement (CS+nr), or a stimulus that was never reinforced (CS-). Parent-reported internalizing symptoms were measured using Revised Child Anxiety and Depression Scales. RESULTS: Functional connectivity between the NAcc and amygdala differentiated the stimuli, such that connectivity increased for the CS+r (p = .023) but not for the CS+nr and CS-. Adolescents with greater internalizing symptoms demonstrated greater positive functional connectivity for the CS- (p = .041). CONCLUSIONS: Adolescents show heightened NAcc-amygdala functional connectivity during escape from threat. Higher anxiety and depression symptoms are associated with elevated NAcc-amygdala connectivity during safety, which may reflect poor safety versus threat discrimination.

11.
Nucleic Acids Res ; 50(16): 9521-9533, 2022 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-36018803

RESUMO

Reactive oxygen species attack the structure of DNA, thus altering its base-pairing properties. Consequently, oxidative stress-associated DNA lesions are a major source of the mutation load that gives rise to cancer and other diseases. Base excision repair (BER) is the pathway primarily tasked with repairing DNA base damage, with apurinic/apyrimidinic endonuclease (APE1) having both AP-endonuclease and 3' to 5' exonuclease (exo) DNA cleavage functions. The lesion 8-oxo-7,8-dihydroguanine (8-oxoG) can enter the genome as either a product of direct damage to the DNA, or through polymerase insertion at the 3'-end of a DNA strand during replication or repair. Importantly, 3'-8-oxoG impairs the ligation step of BER and therefore must be removed by the exo activity of a surrogate enzyme to prevent double stranded breaks and cell death. In the present study, we use X-ray crystallography to characterize the exo activity of APE1 on 3'-8-oxoG substrates. These structures support a unified APE1 exo mechanism that differs from its more canonical AP-endonuclease activity. In addition, through complementation of the structural data with enzyme kinetics and binding studies employing both wild-type and rationally designed APE1 mutants, we were able to identify and characterize unique protein: DNA contacts that specifically mediate 8-oxoG removal by APE1.


Assuntos
Dano ao DNA , Endonucleases , Endonucleases/metabolismo , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Reparo do DNA/genética , DNA/química
12.
Proc Natl Acad Sci U S A ; 118(20)2021 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-33972441

RESUMO

Neuromodulation of immune function by stimulating the autonomic connections to the spleen has been demonstrated in rodent models. Consequently, neuroimmune modulation has been proposed as a new therapeutic strategy for the treatment of inflammatory conditions. However, demonstration of the translation of these immunomodulatory mechanisms in anatomically and physiologically relevant models is still lacking. Additionally, translational models are required to identify stimulation parameters that can be transferred to clinical applications of bioelectronic medicines. Here, we performed neuroanatomical and functional comparison of the mouse, rat, pig, and human splenic nerve using in vivo and ex vivo preparations. The pig was identified as a more suitable model of the human splenic innervation. Using functional electrophysiology, we developed a clinically relevant marker of splenic nerve engagement through stimulation-dependent reversible reduction in local blood flow. Translation of immunomodulatory mechanisms were then assessed using pig splenocytes and two models of acute inflammation in anesthetized pigs. The pig splenic nerve was shown to locally release noradrenaline upon stimulation, which was able to modulate cytokine production by pig splenocytes. Splenic nerve stimulation was found to promote cardiovascular protection as well as cytokine modulation in a high- and a low-dose lipopolysaccharide model, respectively. Importantly, splenic nerve-induced cytokine modulation was reproduced by stimulating the efferent trunk of the cervical vagus nerve. This work demonstrates that immune responses can be modulated by stimulation of spleen-targeted autonomic nerves in translational species and identifies splenic nerve stimulation parameters and biomarkers that are directly applicable to humans due to anatomical and electrophysiological similarities.


Assuntos
Sistema Imunitário/inervação , Imunomodulação/efeitos dos fármacos , Baço/imunologia , Sistema Nervoso Simpático/imunologia , Nervo Vago/imunologia , Animais , Feminino , Expressão Gênica , Humanos , Sistema Imunitário/efeitos dos fármacos , Inflamação , Interleucina-6/genética , Interleucina-6/imunologia , Lipopolissacarídeos/farmacologia , Camundongos , Microcirculação/efeitos dos fármacos , Microcirculação/genética , Microcirculação/imunologia , Norepinefrina/farmacologia , Ratos , Especificidade da Espécie , Baço/efeitos dos fármacos , Baço/inervação , Baço/patologia , Suínos , Sistema Nervoso Simpático/efeitos dos fármacos , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/imunologia , Nervo Vago/efeitos dos fármacos , Estimulação do Nervo Vago/métodos
13.
J Ren Nutr ; 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38848806

RESUMO

OBJECTIVE: Malnutrition is highly prevalent in patients with kidney failure. Since body weight does not reflect body composition, other methods are needed to determine muscle mass, often estimated by fat-free mass (FFM). Bioimpedance spectroscopy (BIS) is frequently used for monitoring body composition in patients with kidney failure. Unfortunately, BIS-derived lean tissue mass (LTMBIS) is not suitable for comparison with FFM cutoff values for the diagnosis of malnutrition, or for calculating dietary protein requirements. Hypothetically, FFM could be derived from BIS (FFMBIS). This study aims to compare FFMBIS and LTMBIS with computed tomography (CT) derived FFM (FFMCT). Secondarily, we aimed to explore the impact of different methods on calculated protein requirements. METHODS: CT scans of 60 patients with kidney failure stages 4-5 were analyzed at the L3 level for muscle cross-sectional area, which was converted to FFMCT. Spearman rank correlation coefficient and 95% limits of agreement were calculated to compare FFMBIS and LTMBIS with FFMCT. Protein requirements were determined based on FFMCT, FFMBIS, and adjusted body weight. Deviations over 10% were considered clinically relevant. RESULTS: FFMCT correlated most strongly with FFMBIS (r = 0.78, P < .001), in males (r = 0.72, P < .001) and in females (r = 0.60, P < .001). A mean difference of -0.54 kg was found between FFMBIS and FFMCT (limits of agreement: -14.88 to 13.7 kg, P = .544). Between LTMBIS and FFMCT a mean difference of -12.2 kg was apparent (limits of agreement: -28.7 to 4.2 kg, P < .001). Using FFMCT as a reference, FFMBIS best predicted protein requirements. The mean difference between protein requirements according to FFMBIS and FFMCT was -0.7 ± 9.9 g in males and -0.9 ± 10.9 g in females. CONCLUSION: FFMBIS correlates well with FFMCT at a group level, but shows large variation within individuals. As expected, large clinically relevant differences were observed in calculated protein requirements.

14.
Med Teach ; : 1-5, 2024 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-38808734

RESUMO

Medical trainee well-being is often met with generalized solutions that overlook substantial individual variations in mental health predisposition and stress reactivity. Precision medicine leverages individual environmental, genetic, and lifestyle factors to tailor preventive and therapeutic interventions. In addition, an exclusive focus on clinical mental illness tends to disregard the importance of supporting the positive aspects of medical trainee well-being. We introduce a novel precision well-being framework for medical education that is built on a comprehensive and individualized view of mental health, combining measures from mental health and positive psychology in a unified, data-driven framework. Unsupervised machine learning techniques commonly used in precision medicine were applied to uncover patterns within multidimensional mental health data of medical students. Using data from 3,632 US medical students, clusters were formulated based on recognized metrics for depression, anxiety, and flourishing. The analysis identified three distinct clusters. Membership in the 'Healthy Flourishers' well-being phenotype was associated with no signs of anxiety or depression while simultaneously reporting high levels of flourishing. Students in the 'Getting By' cluster reported mild anxiety and depression and diminished flourishing. Membership in the 'At-Risk' cluster was associated with high anxiety and depression, languishing, and increased suicidality. Nearly half (49%) of the medical students surveyed were classified as 'Healthy Flourishers', whereas 36% were grouped into the 'Getting-By' cluster and 15% were identified as 'At-Risk'. Findings show that a substantial portion of medical students report diminished well-being during their studies, with a significant number struggling with mental health challenges. This novel precision well-being framework represents an integrated empirical model that classifies individual medical students into distinct and meaningful well-being phenotypes based on their holistic mental health. This approach has direct applicability to student support and can be used to evaluate the effectiveness of personalized intervention strategies stratified by cluster membership.

15.
Int J Sport Nutr Exerc Metab ; 34(4): 189-198, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38604602

RESUMO

Whey protein ingestion during recovery from exercise increases myofibrillar but not muscle connective protein synthesis rates. It has been speculated that whey protein does not provide sufficient glycine to maximize postexercise muscle connective protein synthesis rates. In the present study, we assessed the impact of coingesting different amounts of collagen with whey protein as a nutritional strategy to increase plasma glycine availability during recovery from exercise. In a randomized, double-blind, crossover design, 14 recreationally active men (age: 26 ± 5 years; body mass index: 23.8 ± 2.1 kg·m-2) ingested in total 30 g protein, provided as whey protein with 0 g (WHEY), 5 g (WC05); 10 g (WC10), and 15 g (WC15) of collagen protein immediately after a single bout of resistance exercise. Blood samples were collected frequently over 6 hr of postexercise recovery to assess postprandial plasma amino acid kinetics and availability. Protein ingestion strongly increased plasma amino acid concentrations (p < .001) with no differences in plasma total amino acid availability between treatments (p > .05). The postprandial rise in plasma leucine and essential amino acid availability was greater in WHEY compared with the WC10 and WC15 treatments (p < .05). Plasma glycine and nonessential amino acid concentrations declined following whey protein ingestion but increased following collagen coingestion (p < .05). Postprandial plasma glycine availability averaged -8.9 ± 5.8, 9.2 ± 3.7, 23.1 ± 6.5, and 39.8 ± 11.0 mmol·360 min/L in WHEY, WC05, WC10, and WC15, respectively (incremental area under curve values, p < .05). Coingestion of a small amount of collagen (5 g) with whey protein (25 g) is sufficient to prevent the decline in plasma glycine availability during recovery from lower body resistance-type exercise in recreationally active men.


Assuntos
Colágeno , Estudos Cross-Over , Glicina , Proteínas do Soro do Leite , Humanos , Proteínas do Soro do Leite/administração & dosagem , Masculino , Adulto , Glicina/sangue , Glicina/administração & dosagem , Método Duplo-Cego , Adulto Jovem , Período Pós-Prandial , Exercício Físico/fisiologia , Treinamento Resistido , Fenômenos Fisiológicos da Nutrição Esportiva , Aminoácidos/sangue , Aminoácidos/administração & dosagem , Músculo Esquelético/metabolismo
16.
Adapt Phys Activ Q ; : 1-20, 2024 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-39209293

RESUMO

This study examined doctoral students' occupational socialization experiences in U.S. adapted physical activity doctoral programs. Twenty-eight doctoral students were recruited and participated in semistructured, in-depth interviews. Interview transcripts were analyzed through a collaborative qualitative analysis, which resulted in the construction of four themes: (a) early socialization experiences foster a positive, but limited impression of physical education and physical activity; (b) doctoral education is pursued to have a greater impact on the disability community; (c) relationships with socializing agents provide support during doctoral education; and (d) coursework and learning in the community facilitate preparation for faculty roles. The findings indicate that there are several similarities between doctoral students and their peers in other doctoral degree programs. Some of these similarities point to issues that may concern prospective doctoral students and faculty members in adapted physical activity terminal degree programs.

17.
Beilstein J Org Chem ; 20: 2455-2460, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39376490

RESUMO

A change in mechanism was observed in the hypervalent iodine-mediated cyclization of N-alkenylamides when the carbon chain between the alkene and the amide increased from two to three atoms. In the latter case, cyclization at the amide nitrogen to form the pyrrolidine ring was favored over cyclization at the amide oxygen. A DFT study was undertaken to rationalize the change in mechanism of this cyclization process. In addition, reaction conditions were developed, and the scope of this cyclization studied.

18.
J Am Chem Soc ; 145(21): 11735-11744, 2023 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-37195014

RESUMO

Lytic polysaccharide monooxygenases have received significant attention as catalytic convertors of biomass to biofuel. Recent studies suggest that its peroxygenase activity (i.e., using H2O2 as an oxidant) is more important than its monooxygenase functionality. Here, we describe new insights into peroxygenase activity, with a copper(I) complex reacting with H2O2 leading to site-specific ligand-substrate C-H hydroxylation. [CuI(TMG3tren)]+ (1) (TMG3tren = 1,1,1-Tris{2-[N2-(1,1,3,3-tetramethylguanidino)]ethyl}amine) and a dry source of hydrogen peroxide, (o-Tol3P═O·H2O2)2 react in the stoichiometry, [CuI(TMG3tren)]+ + H2O2 → [CuI(TMG3tren-OH)]+ + H2O, wherein a ligand N-methyl group undergoes hydroxylation giving TMG3tren-OH. Furthermore, Fenton-type chemistry (CuI + H2O2 → CuII-OH + ·OH) is displayed, in which (i) a Cu(II)-OH complex could be detected during the reaction and it could be separately isolated and characterized crystallographically and (ii) hydroxyl radical (·OH) scavengers either quenched the ligand hydroxylation reaction and/or (iii) captured the ·OH produced.


Assuntos
Cobre , Peróxido de Hidrogênio , Cobre/química , Peróxido de Hidrogênio/química , Hidroxilação , Ligantes , Oxigenases de Função Mista/química , Radical Hidroxila/química , Oxirredução
19.
J Am Chem Soc ; 145(29): 16015-16025, 2023 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-37441786

RESUMO

Lytic polysaccharide monooxygenases (LPMOs) catalyze the degradation of recalcitrant carbohydrate polysaccharide substrates. These enzymes are characterized by a mononuclear Cu(I) active site with a three-coordinate T-shaped "His-brace" configuration including the N-terminal histidine and its amine group as ligands. This study explicitly investigates the electronic structure of the d10 Cu(I) active site in a LPMO using Kß X-ray emission spectroscopy (XES). The lack of inversion symmetry in the His-brace site enables the 3d/p mixing required for intensity in the Kß valence-to-core (VtC) XES spectrum of Cu(I)-LPMO. These Kß XES data are correlated to density functional theory (DFT) calculations to define the bonding, and in particular, the frontier molecular orbital (FMO) of the Cu(I) site. These experimentally validated DFT calculations are used to evaluate the reaction coordinate for homolytic cleavage of the H2O2 O-O bond and understand the contribution of this FMO to the low barrier of this reaction and how the geometric and electronic structure of the Cu(I)-LPMO site is activated for rapid reactivity with H2O2.


Assuntos
Peróxido de Hidrogênio , Oxigenases de Função Mista , Oxigenases de Função Mista/química , Polissacarídeos/metabolismo , Domínio Catalítico , Espectrometria por Raios X
20.
Br J Cancer ; 128(2): 354-362, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36357702

RESUMO

BACKGROUND: Vascular endothelial growth factor inhibitors (VEGFIs) are effective anticancer agents which often induce hypertension. VEGFI-induced hypertension is sodium-sensitive in animal studies. Therefore, the efficacy of dietary sodium restriction (DSR) to prevent VEGFI-induced hypertension in cancer patients was studied. METHODS: Cancer patients with VEGFI-induced hypertension (day mean >135/85 mmHg or a rise in systolic and/or diastolic BP ≥ 20 mmHg) were treated with DSR (aiming at <4 g salt/day). The primary endpoint was the difference in daytime mean arterial blood pressure (MAP) increase between the treatment cycle with and without DSR. RESULTS: During the first VEGFI treatment cycle without DSR, mean daytime MAP increased from 95 to 110 mmHg. During the subsequent treatment cycle with DSR, mean daytime MAP increased from 94 to 102 mmHg. Therefore, DSR attenuated the increase in mean daytime MAP by 7 mmHg (95% CI 1.3-12.0, P = 0.009). DSR prevented the rise in the endothelin-1/renin ratio that normally accompanies VEGFI-induced hypertension (P = 0.020) and prevented the onset of proteinuria: 0.15 (0.10-0.25) g/24 h with DSR versus 0.19 (0.11-0.32) g/24 h without DSR; P = 0.005. DISCUSSION: DSR significantly attenuated VEGFI induced BP rise and proteinuria and thus is an effective non-pharmacological intervention.


Assuntos
Hipertensão , Neoplasias , Sódio na Dieta , Animais , Sódio na Dieta/efeitos adversos , Sódio/efeitos adversos , Fator A de Crescimento do Endotélio Vascular , Hipertensão/induzido quimicamente , Hipertensão/prevenção & controle , Hipertensão/tratamento farmacológico , Pressão Sanguínea/fisiologia , Inibidores da Angiogênese/farmacologia , Neoplasias/tratamento farmacológico , Proteinúria
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