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1.
Daru ; 32(1): 421-434, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38427161

RESUMO

OBJECTIVES: Underreporting of adverse drug reactions (ADRs) limits and delays the detection of signs. The aim of this systematic review with meta-analyses was to synthesize the evidence of educational interventions (EIs) efficacy in health professionals to increase ADR reporting, attitudes, and knowledge of pharmacovigilance. EVIDENCE ACQUISITION: A systematic literature review was carried out to identify randomized clinical trials evaluating the efficacy of EI in pharmacovigilance in health professionals to improve ADR reports, knowledge, and attitude toward pharmacovigilance. ADR reports were pooled by calculating Odds Ratio (OR) with a 95% confidence interval (95%CI), while pharmacovigilance knowledge and attitude were pooled by calculating a mean difference (MD) with 95%CI. In addition, the subanalysis was performed by EI type. Meta-analysis was performed with RevMan 5.4 software. PROSPERO registry CRD42021254270. RESULTS: Eight hundred seventy-five articles were identified as potentially relevant, and 11 were included in the systematic review. Metanalysis showed that EI increased ADR reporting in comparison with control group (OR = 4.74, [95%CI, 2.46 to 9.12], I2 = 93%, 5 studies). In subgroup analysis, the workshops (OR = 6.26, [95%CI, 4.03 to 9.73], I2 = 57%, 3 studies) increased ADR reporting more than telephone-based interventions (OR = 2.59, [95%CI, 0.77 to 8.73], I2 = 29%, 2 studies) or combined interventions (OR = 5.14, [95%CI, 0.97 to 27.26], I2 = 93%, 3 studies). No difference was observed in pharmacovigilance knowledge. However, the subanalysis revealed that workshops increase pharmacovigilance knowledge (SMD = 1.85 [95%CI, 1.44 to 2.27], 1 study). Only one study evaluated ADR reporting attitude among participants and showed a positive effect after the intervention. CONCLUSION: EI improves ADR reports and increases pharmacovigilance knowledge. Workshops are the most effective EI to increase ADR reporting.


Assuntos
Sistemas de Notificação de Reações Adversas a Medicamentos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Conhecimentos, Atitudes e Prática em Saúde , Pessoal de Saúde , Farmacovigilância , Humanos , Pessoal de Saúde/educação , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/prevenção & controle
2.
Cir Cir ; 90(3): 353-358, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35636937

RESUMO

INTRODUCTION: Midazolam is a benzodiazepine used for sedation, however, can cause respiratory depression and increases morbidity in patients. Melatonin is an effective alternative to manage anxiety in the perioperative period and could help to reduce the use of benzodiazepines during surgery. The aim of this clinical trial was to determine the efficacy of pre-operative sedation with a single-dose melatonin to reduce intraoperative use of midazolam in women under total abdominal hysterectomy (TAH). MATERIALS AND METHODS: This is a double-blind randomized clinical trial conducted in women over 25 years, scheduled for TAH, with American Society of Anesthesiologists Grade I or II. Each patient was randomly assigned to receive 5 mg of melatonin prolonged-release oral capsules or placebo. Midazolam use for anesthetic management was the decision of the treating anesthesiologist and sedation status was determined using the observer's assessment of alertness/sedation scale. RESULTS: In patients receiving melatonin, the use of midazolam during surgery was less than in patients receiving placebo. In addition, melatonin produces sedation 30 min after administration, the sedative effect was maintained at 60- and 90-min. Furthermore, hospital stay was shorter in patients who received melatonin (p = 0.006). CONCLUSION: Melatonin is effective for reduces intraoperative midazolam consumption and hospital stay in women undergoing TAH.


INTRODUCCIÓN: El midazolam es una benzodiazepina utilizada para la sedación, sin embargo, puede causar depresión respiratoria y aumentar la morbilidad en los pacientes. La melatonina es una alternativa eficaz para controlar la ansiedad en el período perioperatorio y podría ayudar a reducir el uso de benzodiazepinas durante la cirugía. El objetivo de este ensayo clínico fue determinar la eficacia de la sedación preoperatoria con una dosis única de melatonina para reducir el uso intraoperatorio de midazolam en mujeres sometidas a histerectomía abdominal total (HTA). MATERIAL Y MÉTODOS: Se trata de un ensayo clínico aleatorizado doble ciego realizado en mujeres mayores de 25 años, programadas para TAH, con American Society of Anesthesiologists Grado I o II. Cada paciente fue asignado al azar para recibir 5 mg de cápsulas orales de liberación prolongada de melatonina o placebo. El uso de midazolam para el manejo anestésico fue decisión del anestesiólogo tratante y el estado de sedación se determinó mediante la escala OAA/S. RESULTADOS: En las pacientes que recibieron melatonina, el uso de midazolam durante la cirugía fue menor que en las pacientes que recibieron placebo. Además, la melatonina produce sedación 30 min después de la administración, el efecto sedante se mantuvo a los 60 y 90 min. Además, la estancia hospitalaria fue más corta en los pacientes que recibieron melatonina (p = 0.006). CONCLUSIÓN: La melatonina es eficaz para reducir el consumo de midazolam intraoperatorio y la estancia hospitalaria en mujeres sometidas a HTA.


Assuntos
Melatonina , Midazolam , Método Duplo-Cego , Feminino , Humanos , Hipnóticos e Sedativos/uso terapêutico , Histerectomia , Melatonina/uso terapêutico , Midazolam/uso terapêutico
3.
J Obstet Gynaecol Can ; 43(6): 766-768, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34099221

RESUMO

The concept of prenatal physical activity has transitioned from a potentially risky behaviour to a prescription to improve maternal-fetal health. Pregnant women who are hospitalized because of a complication should continue to engage in light activities of daily living given the known adverse effects of maternal bedrest. Because the amount physical activity performed by pregnant women while in hospital not been documented; we compared levels of physical activity between women who were and were not hospitalized during pregnancy. We found that hospitalized pregnant women self-impose bedrest even in the absence of a medical recommendation.


Assuntos
Repouso em Cama , Exercício Físico , Hospitalização , Atividades Cotidianas , Feminino , Humanos , Gravidez , Gestantes , Cuidado Pré-Natal
4.
Physiol Rep ; 8(13): e14504, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32633077

RESUMO

INTRODUCTION: Gestational diabetes mellitus (GDM) is associated with vascular dysfunction. Sympathetic nervous system activity (SNA) is an important regulator of vascular function, and is influenced by glucose and insulin. The association between GDM and SNA (re)activity is unknown. We hypothesize that women with GDM would have increased SNA during baseline and during stress. METHODS: Eighteen women with GDM and 18 normoglycemic pregnant women (controls) were recruited. Muscle SNA (MSNA; peroneal microneurography) was assessed at rest, during a cold pressor test (CPT) and during peripheral chemoreflex deactivation (hyperoxia). Spontaneous sympathetic baroreflex gain was quantified versus diastolic pressure at rest and during hyperoxia. RESULTS: Age, gestational age (third trimester) and pre-pregnancy body mass index and baseline MSNA was not different among the groups. Women with GDM had a similar increase in MSNA, but a greater pressor response to CPT compared to controls (% change in MAP 17 ± 7% vs. 9 ± 9%; p = .004). These data are consistent with a greater neurovascular transduction in GDM (% change in total peripheral resistance/% change in burst frequency [BF]: 15.9 ± 30.2 vs. -5.2 ± 16.4, p = .03). Interestingly, women with GDM had a greater reduction in MSNA during hyperoxia (% change in BF -30 ± 19% vs. -6 ± 17%; p = .01). CONCLUSION: Women diagnosed with GDM have similar basal SNA versus normoglycemic pregnant women, but greater neurovascular transduction, meaning a greater influence of the sympathetic nerve activity in these women. We also document evidence of chemoreceptor hyperactivity, which may influence SNA in women with GDM but not in controls.


Assuntos
Diabetes Gestacional/fisiopatologia , Sistema Nervoso Simpático/fisiopatologia , Adulto , Feminino , Humanos , Músculo Liso Vascular/inervação , Músculo Liso Vascular/fisiopatologia , Gravidez , Reflexo
5.
Appl Physiol Nutr Metab ; 45(9): 1041-1044, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32302501

RESUMO

Associations between prepregnancy body mass index, gestational weight gain, maternal age, and basal sympathetic nervous system activity (SNA) in normotensive pregnant women have not been explored. Retrospective analysis of microneurography records from 74 normotensive pregnant women during their third trimester indicated that although pregnancy is associated with rapid weight gain, this does not influence SNA. There were also no associations between maternal age and SNA, but more studies are needed to confirm this interpretation. Novelty Neither age nor excessive weight gain appears to influence sympathetic activity during normotensive pregnancy.


Assuntos
Fatores Etários , Índice de Massa Corporal , Ganho de Peso na Gestação , Sistema Nervoso Simpático/fisiologia , Adulto , Pressão Sanguínea , Feminino , Humanos , Gravidez , Terceiro Trimestre da Gravidez , Estudos Retrospectivos
6.
Med Sci Sports Exerc ; 52(4): 801-809, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31688654

RESUMO

PURPOSE: To determine the role of moderate-to-vigorous physical activity (MVPA) and sedentary behavior in flow-mediated dilation (FMD) and glucose metabolism during late pregnancy. METHODS: Seventy normotensive, euglycemic pregnant women (31.6 ± 2.9 yr) in their third trimester (28-39 wk) were recruited. After a fasted blood sample; FMD was measured (brachial artery Doppler ultrasonography, normalized for the shear stimulus [area under the curve]). Anterograde and retrograde shear rate were estimated. Physical activity (MVPA) and sedentary behavior were assessed via accelerometry for seven consecutive days (Actigraph wGT3X-BT). We categorized the women as active (>150 min·wk) or inactive (<150 min·wk) according to their accelerometry data. Data were corrected for age and gestational age. RESULTS: On average, women were sedentary 67.1% ± 8.2% of their waking hours. Active pregnant women (>150 min·wk MVPA, n = 32) engaged in 266.7 ± 99.3 min·wk MVPA, whereas inactive pregnant women (<150 min·wk MVPA, n = 38) engaged in 76.1 ± 42.5 min·wk MVPA. The FMD response (normalized to the magnitude of shear stress stimulus) was greater in active compared with inactive pregnant women (6.5 ± 4.4 a.u. vs 3.9 ± 3.5 a.u.; F = 4.619; P = 0.005). The MVPA in active pregnant women was inversely correlated with insulin concentrations (r = -0.556; P = 0.03). In inactive pregnant women, higher amounts of sedentary behavior were associated with lower amounts of retrograde shear rate (r = 0.504; P = 0.02), retrograde blood flow (r = 0.499; P = 0.02), and retrograde velocity (r = 0.508; P = 0.02) during baseline, but not correlated with the FMD response. CONCLUSIONS: Engaging in MVPA during pregnancy is associated with improved FMD and a lower insulin concentration. Sedentary behavior was not associated with FMD responses.


Assuntos
Velocidade do Fluxo Sanguíneo , Glicemia/metabolismo , Exercício Físico/fisiologia , Terceiro Trimestre da Gravidez/sangue , Terceiro Trimestre da Gravidez/fisiologia , Comportamento Sedentário , Vasodilatação , Adulto , Artéria Braquial/anatomia & histologia , Artéria Braquial/diagnóstico por imagem , Artéria Braquial/fisiologia , Endotélio Vascular/fisiologia , Feminino , Hemodinâmica , Humanos , Insulina/sangue , Gravidez , Ultrassonografia Doppler
7.
Saudi J Biol Sci ; 26(7): 1613-1620, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31762635

RESUMO

The anti-acetylcholinesterase, larvicidal, antifeedant activities and general toxicity of 15 semisynthetic eugenol derivatives based on clove oil (including the own oil), were evaluated against the maize armyworm, Spodoptera frugiperda (J.E. Smith). Therefore, promising eugenol molecules were classified with larvicidal, anti-acetylcholinesterase and antifeedant activities for controlling this pest. During structure-activity relationship studies and physicochemical profile analysis, it was found that among tested molecules 1-15, eugenol 1, prenyl eugenol 4, isoeugenol 8 and isoeugenol acetate 11 exhibited lethal effects LD50 at concentrations <1 mg/g of insect. On the other hand, eugenol 1, metallyl eugenol 3, isoeugenol 8 and isoeugenol acetate 11 showed a good antifeedant activity (CE50 = 158-209 µg/mL) with a high antifeedant index (70-78%) at concentration 1000 µg/mL, possessing a weak anti-acetylcholinesterase activity (IC50 = 21-31 µg/mL). According to their ecotoxicological profiles (LC50 = 2033.1-6303.8 µg/mL on Artemia salina larvae), isoeugenol 8 and its acetate derivative 11 could be potential used in control of the growth, feeding, or reproduction of S. frugiperda larvae, acting as moderate insecticidal acetylcholinesterase inhibitors and/or antifeedant molecules. Such structure-activity relationship studies could stimulate the identification of lead structures from natural sources for the development of larvicidal and deterrent products against S. frugiperda and related insect pests.

8.
J Physiol ; 597(14): 3687-3696, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31106429

RESUMO

KEY POINTS: Normotensive pregnancy is associated with elevated sympathetic nervous system activity yet normal or reduced blood pressure. It represents a unique period of apparent healthy sympathetic hyperactivity. The present study models the blood pressure and heart rate (ECG R-R interval) responses to fluctuations in sympathetic nervous system activity aiming to understand neurocardiovascular transduction. The reported data clearly demonstrate that transduction of sympathetic nervous system signalling to systemic cardiovascular outcomes is reduced in normotensive pregnancy. These data are important for understanding how blood pressure regulation adapts during normotensive pregnancy and set the foundation for exploring similar mechanisms in hypertensive pregnancies. ABSTRACT: Previously, we described sympathetic nervous system hyperactivity yet decreased blood pressure responses to stress in normotensive pregnancy. To address the hypothesis that pregnant women have blunted neurocardiovascular transduction we assessed the relationship between spontaneous bursts of sympathetic nerve activity (SNA) and fluctuations in mean arterial blood pressure and R-R interval. Resting SNA, blood pressure and ECG were obtained in pregnant (third trimester, n = 18) and non-pregnant (n = 18) women matched for age and pre-/non-pregnant body mass index. Custom software modelled beat-by-beat pressure (photoplethysmography) and R-R interval in relation to sequences of SNA bursts and non-bursts (peroneal microneurography). Sequences were grouped by the number of bursts and non-bursts [singlets, doublets, triplets and quadruplet (four or more)] and mean blood pressure and R-R interval were tracked for 15 subsequent cardiac cycles. Similar sequences were overlaid and averaged. Peak mean pressure in relation to sequences of SNA was reduced in pregnant vs. non-pregnant women (doublets: 1.6 ± 1.1 mmHg vs. 3.6 ± 3.1 mmHg, P < 0.05; triplets: 2.4 ± 1.2 mmHg vs. 3.4 ± 2.1 mmHg, P < 0.05; quadruplets: 3.0 ± 1.0 mmHg vs. 5.5 ± 3.7 mmHg, P < 0.05). The nadir R-R interval following burst sequences was also smaller in pregnant vs. non-pregnant women (singlets: -0.01 ± 0.01 s vs. -0.04 ± 0.04 s, P < 0.05; doublets: -0.02 ± 0.03 s vs. -0.05 ± 0.04 s, P < 0.05; triplets: -0.02 ± 0.01 s vs. -0.07 ± 0.04 s, P < 0.05; quadruplets: -0.01 ± 0.01 s vs. -0.09 ± 0.09 s, P < 0.05). There were no differences between groups in the mean arterial pressure and R-R interval responses to non-burst sequences. Our data clearly indicate blunted systemic neurocardiovascular transduction during normotensive pregnancy. We propose that blunted transduction is a positive adaptation protecting pregnant women from the cardiovascular consequences of sympathetic hyperactivity.


Assuntos
Sistema Nervoso Simpático/fisiologia , Adulto , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Feminino , Frequência Cardíaca/fisiologia , Humanos , Gravidez , Terceiro Trimestre da Gravidez/fisiologia , Descanso/fisiologia
9.
Adv Sci (Weinh) ; 5(6): 1700732, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29938164

RESUMO

Frustrated Lewis pairs (FLPs) created by sterically hindered Lewis acids and Lewis bases have shown their capacity for capturing and reacting with a variety of small molecules, including H2 and CO2, and thereby creating a new strategy for CO2 reduction. Here, the photocatalytic CO2 reduction behavior of defect-laden indium oxide (In2O3-x (OH) y ) is greatly enhanced through isomorphous substitution of In3+ with Bi3+, providing fundamental insights into the catalytically active surface FLPs (i.e., In-OH···In) and the experimentally observed "volcano" relationship between the CO production rate and Bi3+ substitution level. According to density functional theory calculations at the optimal Bi3+ substitution level, the 6s2 electron pair of Bi3+ hybridizes with the oxygen in the neighboring In-OH Lewis base site, leading to mildly increased Lewis basicity without influencing the Lewis acidity of the nearby In Lewis acid site. Meanwhile, Bi3+ can act as an extra acid site, serving to maximize the heterolytic splitting of reactant H2, and results in a more hydridic hydride for more efficient CO2 reduction. This study demonstrates that isomorphous substitution can effectively optimize the reactivity of surface catalytic active sites in addition to influencing optoelectronic properties, affording a better understanding of the photocatalytic CO2 reduction mechanism.

10.
Pharmacol Res ; 132: 160-167, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29684673

RESUMO

The Developmental Origins of Health and Disease suggest the in utero environment programs offspring obesity and cardiovascular disease. Therefore, there is a need to implement safe therapeutic interventions that do not involve the intake of medications or biological products during pregnancy that can improve maternal and fetal health. Prenatal exercise is established to promote maternal and fetal health. It is generally recommended that women accumulate at least 150 min per week of moderate-intensity exercise. It has been demonstrated that prenatal exercise maintains healthy weight gain and improves maternal glucose control, maternal cardiac autonomic control, placental efficiency (increases angiogenesis, downregulates genes involved in fatty acid transport and insulin transport across the placenta, and upregulates genes involved in amino acid transport across the placenta), and oxidative stress. These adaptations following exercise improve maternal metabolism and provide adequate uteroplacental perfusion. In this review, we will focus on exercise as a therapeutic intervention to optimize fetal weight. It has been established that prenatal exercise does not increase the risk of having a small for gestational age baby. To the contrary, prenatal exercise has been associated with the prevention of excessive fat accumulation in the newborn and the maintenance of fetal muscle mass.


Assuntos
Exercício Físico , Desenvolvimento Fetal , Animais , Feminino , Humanos , Saúde Materna , Gravidez
12.
Exp Physiol ; 103(3): 318-323, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29336094

RESUMO

NEW FINDINGS: What is the main observation in this case? The main observation of this case report is that during pregnancy there is a progressive sympatho-excitation in basal conditions and under stress, which is offset by a concurrent reduction in neurovascular transduction. Strong correlations between autonomic nervous system activity and sex hormones (oestrogen and progesterone), vasopressin and aldosterone were found. What insights does it reveal? Our findings suggest that hormonal surges might be associated with central sympathetic activation. ABSTRACT: The adaptations of sympathetic nerve activity (SNA) during pregnancy remain poorly understood. An increase in blood volume, cardiac output and SNA, with a concomitant drop in total peripheral resistance (TPR), suggest that during pregnancy there is a reduced transduction of SNA into TPR. Most of these findings have originated from cross-sectional studies; thus, we conducted a longitudinal assessment of SNA and TPR in two participants. Measurements were made before pregnancy (early follicular phase), on four occasions during pregnancy and at 2 months postpartum. Mean arterial pressure and cardiac output were used to calculate TPR. The SNA was measured using microneurography (peroneal nerve). There was a gestation-dependent increase in SNA burst frequency (r2  = 0.96, P = 0.009). Neurovascular transduction, however, decreased by 53% in both women. Sympathetic hyperactivity was reversed postpartum, whereas neurovascular transduction remained lower. These longitudinal data highlight the progressive sympatho-excitation of pregnancy, which is offset by a concurrent reduction in neurovascular transduction.


Assuntos
Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Débito Cardíaco/fisiologia , Sistema Nervoso Simpático/fisiologia , Adulto , Feminino , Frequência Cardíaca/fisiologia , Humanos , Estudos Longitudinais , Período Pós-Parto/fisiologia , Gravidez , Adulto Jovem
13.
Angew Chem Int Ed Engl ; 56(22): 6329-6334, 2017 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-28393431

RESUMO

Germanium nanocrystals (ncGe) have not received as much attention as silicon nanocrystals (ncSi). However, Ge has demonstrated superiority over Si nanomaterials in some applications. Examples include, high charge-discharge rate lithium-ion batteries, small band-gap opto-electronic devices, and photo-therapeutics. When stabilized in an oxide matrix (ncGe/GeOx ), its high charge-retention has enabled non-volatile memories. It has also found utility as a high-capacity anode material for Li-ion batteries with impressive stability. Herein, we report an organic-free synthesis of size-controlled ncGe in a GeOx matrix as well as freestanding ncGe, via the thermal disproportionation of GeO prepared from thermally induced dehydration of Ge(OH)2 . The photothermal effect of ncGe, quantified by Raman spectroscopy, is found to be size dependent and superior to ncSi. This advance suggests applications of ncGe in photothermal therapy, desalination, and catalysis.

14.
Proc Natl Acad Sci U S A ; 113(50): E8011-E8020, 2016 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-27911785

RESUMO

In2O3-x(OH)y nanoparticles have been shown to function as an effective gas-phase photocatalyst for the reduction of CO2 to CO via the reverse water-gas shift reaction. Their photocatalytic activity is strongly correlated to the number of oxygen vacancy and hydroxide defects present in the system. To better understand how such defects interact with photogenerated electrons and holes in these materials, we have studied the relaxation dynamics of In2O3-x(OH)y nanoparticles with varying concentration of defects using two different excitation energies corresponding to above-band-gap (318-nm) and near-band-gap (405-nm) excitations. Our results demonstrate that defects play a significant role in the excited-state, charge relaxation pathways. Higher defect concentrations result in longer excited-state lifetimes, which are attributed to improved charge separation. This correlates well with the observed trends in the photocatalytic activity. These results are further supported by density-functional theory calculations, which confirm the positions of oxygen vacancy and hydroxide defect states within the optical band gap of indium oxide. This enhanced understanding of the role these defects play in determining the optoelectronic properties and charge carrier dynamics can provide valuable insight toward the rational development of more efficient photocatalytic materials for CO2 reduction.

15.
Adv Sci (Weinh) ; 3(10): 1600189, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27840802

RESUMO

The reverse water gas shift (RWGS) reaction driven by Nb2O5 nanorod-supported Pd nanocrystals without external heating using visible and near infrared (NIR) light is demonstrated. By measuring the dependence of the RWGS reaction rates on the intensity and spectral power distribution of filtered light incident onto the nanostructured Pd@Nb2O5 catalyst, it is determined that the RWGS reaction is activated photothermally. That is the RWGS reaction is initiated by heat generated from thermalization of charge carriers in the Pd nanocrystals that are excited by interband and intraband absorption of visible and NIR light. Taking advantage of this photothermal effect, a visible and NIR responsive Pd@Nb2O5 hybrid catalyst that efficiently hydrogenates CO2 to CO at an impressive rate as high as 1.8 mmol gcat-1 h-1 is developed. The mechanism of this photothermal reaction involves H2 dissociation on Pd nanocrystals and subsequent spillover of H to the Nb2O5 nanorods whereupon adsorbed CO2 is hydrogenated to CO. This work represents a significant enhancement in our understanding of the underlying mechanism of photothermally driven CO2 reduction and will help guide the way toward the development of highly efficient catalysts that exploit the full solar spectrum to convert gas-phase CO2 to valuable chemicals and fuels.

16.
Nat Commun ; 7: 12553, 2016 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-27550234

RESUMO

Silicon constitutes 28% of the earth's mass. Its high abundance, lack of toxicity and low cost coupled with its electrical and optical properties, make silicon unique among the semiconductors for converting sunlight into electricity. In the quest for semiconductors that can make chemicals and fuels from sunlight and carbon dioxide, unfortunately the best performers are invariably made from rare and expensive elements. Here we report the observation that hydride-terminated silicon nanocrystals with average diameter 3.5 nm, denoted ncSi:H, can function as a single component heterogeneous reducing agent for converting gaseous carbon dioxide selectively to carbon monoxide, at a rate of hundreds of µmol h(-1) g(-1). The large surface area, broadband visible to near infrared light harvesting and reducing power of SiH surface sites of ncSi:H, together play key roles in this conversion. Making use of the reducing power of nanostructured hydrides towards gaseous carbon dioxide is a conceptually distinct and commercially interesting strategy for making fuels directly from sunlight.

17.
ACS Nano ; 10(5): 5578-86, 2016 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-27159793

RESUMO

The development of strategies for increasing the lifetime of photoexcited charge carriers in nanostructured metal oxide semiconductors is important for enhancing their photocatalytic activity. Intensive efforts have been made in tailoring the properties of the nanostructured photocatalysts through different ways, mainly including band-structure engineering, doping, catalyst-support interaction, and loading cocatalysts. In liquid-phase photocatalytic dye degradation and water splitting, it was recently found that nanocrystal superstructure based semiconductors exhibited improved spatial separation of photoexcited charge carriers and enhanced photocatalytic performance. Nevertheless, it remains unknown whether this strategy is applicable in gas-phase photocatalysis. Using porous indium oxide nanorods in catalyzing the reverse water-gas shift reaction as a model system, we demonstrate here that assembling semiconductor nanocrystals into superstructures can also promote gas-phase photocatalytic processes. Transient absorption studies prove that the improved activity is a result of prolonged photoexcited charge carrier lifetimes due to the charge transfer within the nanocrystal network comprising the nanorods. Our study reveals that the spatial charge separation within the nanocrystal networks could also benefit gas-phase photocatalysis and sheds light on the design principles of efficient nanocrystal superstructure based photocatalysts.

18.
Clin Sci (Lond) ; 130(7): 539-49, 2016 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-26733722

RESUMO

Circulating factors have been proposed to play a major role in the pathophysiology of endothelial dysfunction in pre-eclampsia (PE), which is defined as new-onset hypertension with proteinuria after 20 weeks of gestation. However, the mechanisms leading to altered vascular reactivity remain unclear. We hypothesized that circulating factors lead to endothelial dysfunction by increasing oxidative stress and reducing nitric oxide (NO) and prostaglandin (PG) bioavailability. Pregnant rat uterine and mesenteric arteries were incubated overnight with 3% normotensive (NP) or PE plasma collected from women upon admission to hospital. Responses to methacholine (MCh) were obtained using wire myography to assess endothelial function pathways. Vascular superoxide level was measured via dihydroethidium staining and nitric oxide synthase (NOS) expression via Western blots. PE plasma significantly increased superoxide levels and impaired endothelial dysfunction in uterine arteries (Emax 79.9±5.6% compared with 44.9±6.3%, P=0.0004), which was restored in the presence of oxidant scavengers or PG synthesis inhibition. Uterine artery vasodilation was abolished in the presence of pan-NOS inhibitor (P<0.0001) in both NP- and PE-treated vessels, but inducible nitric oxide synthase (iNOS)-dependent vasodilation was present only in NP-treated arteries. Uterine arteries exposed to PE plasma exhibit an increased endothelial NOS expression and a decreased iNOS expression. PE plasma did not alter endothelial function in mesenteric arteries, suggesting that the effect of circulating factors was vascular-bed-specific. We have shown that circulating factors lead to endothelial dysfunction via altered oxidative stress and vasodilator pathways. The present study contributes to our understanding of the pathophysiology and finding a potential target for intervention in PE.


Assuntos
Artérias Mesentéricas/metabolismo , Estresse Oxidativo , Pré-Eclâmpsia/sangue , Artéria Uterina/metabolismo , Vasodilatação , Adulto , Animais , Antioxidantes/farmacologia , Biomarcadores/sangue , Inibidores Enzimáticos/farmacologia , Feminino , Humanos , Artérias Mesentéricas/efeitos dos fármacos , Artérias Mesentéricas/fisiopatologia , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo I/antagonistas & inibidores , Óxido Nítrico Sintase Tipo I/metabolismo , Óxido Nítrico Sintase Tipo II/antagonistas & inibidores , Óxido Nítrico Sintase Tipo II/metabolismo , Pré-Eclâmpsia/diagnóstico , Pré-Eclâmpsia/fisiopatologia , Gravidez , Prostaglandinas/metabolismo , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos , Superóxidos/metabolismo , Artéria Uterina/efeitos dos fármacos , Artéria Uterina/fisiopatologia , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologia , Adulto Jovem
19.
J Physiol ; 594(5): 1465-82, 2016 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-26467260

RESUMO

Prenatal hypoxia, a common outcome of pregnancy complications, predisposes offspring to the development of metabolic and cardiovascular disorders in later life. We have previously observed that resveratrol improved cardiovascular and metabolic health in adult male rat offspring exposed to prenatal hypoxia and a postnatal high-fat (HF) diet; however, the effects of resveratrol in female rat offspring are not known. Our aim was to identify the mechanism(s) by which resveratrol may prevent metabolic and cardiac dysfunction in both male and female rat offspring exposed to prenatal hypoxia and a postnatal HF diet. Offspring that experienced normoxia or hypoxia in utero were fed a HF diet or a HF diet supplemented with resveratrol for 9 weeks following weaning. Body composition, metabolic function, in vivo cardiac function and ex vivo cardiac susceptibility to ischaemia-reperfusion (I/R) injury were assessed at 12 weeks of age. Prenatal hypoxia impaired metabolic function in male, but not female, rat offspring fed a HF diet and this was improved by resveratrol supplementation. Prenatal hypoxia also led to reduced recovery from cardiac I/R injury in male, and to a lesser extent in female, rat offspring fed a HF diet. Indices of cardiac oxidative stress after I/R were enhanced in both male and female rat offspring exposed to prenatal hypoxia. Resveratrol improved cardiac recovery from I/R injury and attenuated superoxide levels in both male and female rat offspring. In conclusion, prenatal hypoxia impaired metabolic and cardiac function in a sex-specific manner. Resveratrol supplementation may improve metabolic and cardiovascular health in adult male and female rat offspring exposed to prenatal hypoxia.


Assuntos
Cardiotônicos/farmacologia , Doenças Cardiovasculares/prevenção & controle , Dieta Hiperlipídica/efeitos adversos , Hipóxia Fetal/patologia , Coração/efeitos dos fármacos , Estilbenos/farmacologia , Animais , Cardiotônicos/uso terapêutico , Doenças Cardiovasculares/etiologia , Feminino , Hipóxia Fetal/complicações , Masculino , Contração Miocárdica , Miocárdio/metabolismo , Gravidez , Ratos , Ratos Sprague-Dawley , Resveratrol , Estilbenos/uso terapêutico , Superóxidos/metabolismo , Função Ventricular
20.
Am J Physiol Regul Integr Comp Physiol ; 309(5): R489-98, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26157059

RESUMO

Intrauterine growth restriction (IUGR) has been associated with increased susceptibility to myocardial ischemia-reperfusion (I/R) injury. Exercise is an effective preventive intervention for cardiovascular diseases; however, it may be detrimental in conditions of compromised health. The aim of this study was to determine whether exercise training can improve cardiac performance after I/R injury in IUGR offspring. We used a hypoxia-induced IUGR model by exposing pregnant Sprague-Dawley rats to 21% oxygen (control) or hypoxic (11% oxygen; IUGR) conditions from gestational day 15 to 21. At 10 wk of age, offspring were randomized to a sedentary group or to a 6-wk exercise protocol. Transthoracic echocardiography assessments were performed after 6 wk. Twenty-four hours after the last bout of exercise, ex vivo cardiac function was determined using a working heart preparation. With exercise training, there was improved baseline cardiac performance in male control offspring but a reduced baseline cardiac performance in male IUGR exercised offspring (P < 0.05). In male offspring, exercise decreased superoxide generation in control offspring, while in IUGR offspring, it had the polar opposite effect (interaction P ≤ 0.05). There was no effect of IUGR or exercise on cardiac function in female offspring. In conclusion, in male IUGR offspring, exercise may be a secondary stressor on cardiac function. A reduction in cardiac performance along with an increase in superoxide production in response to exercise was observed in this susceptible group.


Assuntos
Retardo do Crescimento Fetal/etiologia , Hipóxia Fetal/complicações , Traumatismo por Reperfusão Miocárdica/etiologia , Esforço Físico , Efeitos Tardios da Exposição Pré-Natal , Função Ventricular Esquerda , Animais , Modelos Animais de Doenças , Feminino , Retardo do Crescimento Fetal/fisiopatologia , Hipóxia Fetal/fisiopatologia , Masculino , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Miocárdio/metabolismo , Gravidez , Ratos Sprague-Dawley , Fatores de Risco , Fatores Sexuais , Superóxidos/metabolismo , Fatores de Tempo
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