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81.
Fungyi Chow Marianne Pedersén Mariana C. Oliveira 《Journal of applied phycology》2013,25(6):1847-1853
Nitrate reductase (NR), a key enzyme in nitrogen metabolism, has been implicated in the production of nitric oxide (NO) in plants. The effect of photosynthetic electron transport chain inhibitors and NO scavengers or donors on NR activity of Gracilaria chilensis was studied under experimental laboratory conditions. Effective quantum yield (Φ PSII) and NR activity were significantly diminished by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, two photosynthetic electron flux inhibitors of photosystem (PS) II and PSI, respectively, but not by diphenyleneiodonium, a NADPH oxidase inhibitor, indicating a direct dependence of NR activity on the PSII and PSI electron flux. Nitrate reductase activity was sensitive to a decrease or increase of NO levels when NO scavenger (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) and NO donor (sodium nitroprusside) were added. Moreover, the addition of 8Br-cGMP, a secondary signal molecule, stimulated NR activity. These results evidence a modulation of the photosynthetic electron transport chain and NO balance on G. chilensis NR activity. This association could be linked to the crucial tight modulation of nitrogen assimilation and carbon metabolism to guarantee nitrite incorporation into organic compounds and to avoid toxicity by nitrite, reactive oxygen species, or nitric oxide in the cells. Nitric oxide showed to be an important signaling molecule regulating NR activity and cGMP could participate as secondary messenger on this regulation by phosphorylation and desphosphorylation processes. 相似文献
82.
Magdalena Sarah Volz Vanessa Suarez-Contreras Mariana E. Mendonca Fernando Santos Pinheiro Lotfi B. Merabet Felipe Fregni 《PloS one》2013,8(1)
Background/Objective
Transcutaneous electrical stimulation has been proven to modulate nervous system activity, leading to changes in pain perception, via the peripheral sensory system, in a bottom up approach. We tested whether different sensory behavioral tasks induce significant effects in pain processing and whether these changes correlate with cortical plasticity.Methodology/Principal Findings
This randomized parallel designed experiment included forty healthy right-handed males. Three different somatosensory tasks, including learning tasks with and without visual feedback and simple somatosensory input, were tested on pressure pain threshold and motor cortex excitability using transcranial magnetic stimulation (TMS). Sensory tasks induced hand-specific pain modulation effects. They increased pain thresholds of the left hand (which was the target to the sensory tasks) and decreased them in the right hand. TMS showed that somatosensory input decreased cortical excitability, as indexed by reduced MEP amplitudes and increased SICI. Although somatosensory tasks similarly altered pain thresholds and cortical excitability, there was no significant correlation between these variables and only the visual feedback task showed significant somatosensory learning.Conclusions/Significance
Lack of correlation between cortical excitability and pain thresholds and lack of differential effects across tasks, but significant changes in pain thresholds suggest that analgesic effects of somatosensory tasks are not primarily associated with motor cortical neural mechanisms, thus, suggesting that subcortical neural circuits and/or spinal cord are involved with the observed effects. Identifying the neural mechanisms of somatosensory stimulation on pain may open novel possibilities for combining different targeted therapies for pain control. 相似文献83.
Alipio Pinto Mariana Jacobsen Patricia A. Geoghegan Adriana Cangelosi María Laura Cejudo Carla Tironi-Farinati Jorge Goldstein 《PloS one》2013,8(7)
Shiga toxin 2 (Stx2)-producing Escherichia coli (STEC) causes hemorrhagic colitis and hemolytic uremic syndrome (HUS) that can lead to fatal encephalopathies. Neurological abnormalities may occur before or after the onset of systemic pathological symptoms and motor disorders are frequently observed in affected patients and in studies with animal models. As Stx2 succeeds in crossing the blood-brain barrier (BBB) and invading the brain parenchyma, it is highly probable that the observed neurological alterations are based on the possibility that the toxin may trigger the impairment of the neurovascular unit and/or cell damage in the parenchyma. Also, lipopolysaccharide (LPS) produced and secreted by enterohemorrhagic Escherichia coli (EHEC) may aggravate the deleterious effects of Stx2 in the brain. Therefore, this study aimed to determine (i) whether Stx2 affects the neurovascular unit and parenchymal cells, (ii) whether the contribution of LPS aggravates these effects, and (iii) whether an inflammatory event underlies the pathophysiological mechanisms that lead to the observed injury. The administration of a sub-lethal dose of Stx2 was employed to study in detail the motor cortex obtained from a translational murine model of encephalopathy. In the present paper we report that Stx2 damaged microvasculature, caused astrocyte reaction and neuronal degeneration, and that this was aggravated by LPS. Dexamethasone, an anti-inflammatory, reversed the pathologic effects and proved to be an important drug in the treatment of acute encephalopathies. 相似文献
84.
Joshua P. Vogel Maria Regina Torloni Armando Seuc Ana Pilar Betrán Mariana Widmer Jo?o Paulo Souza Mario Merialdi 《PloS one》2013,8(8)
Background
Twin pregnancies in low- and middle-income countries (LMICs) pose a high risk to mothers and newborns due to inherent biological risks and scarcity of health resources. We conducted a secondary analysis of the WHO Global Survey dataset to analyze maternal and perinatal outcomes in twin pregnancies and factors associated with perinatal morbidity and mortality in twins.Methods
We examined maternal and neonatal characteristics in twin deliveries in 23 LMICs and conducted multi-level logistic regression to determine the association between twins and adverse maternal and perinatal outcomes.Results
279,425 mothers gave birth to 276,187 (98.8%) singletons and 6,476 (1.2%) twins. Odds of severe adverse maternal outcomes (death, blood transfusion, ICU admission or hysterectomy) (AOR 1.85, 95% CI 1.60–2.14) and perinatal mortality (AOR 2.46, 95% CI 1.40–4.35) in twin pregnancies were higher, however early neonatal death (AOR 2.50, 95% CI 0.95–6.62) and stillbirth (AOR 1.22, 95% CI 0.58–2.57) did not reach significance. Amongst twins alone, maternal age <18, poor education and antenatal care, nulliparity, vaginal bleeding, non-cephalic presentations, birth weight discordance >15%, born second, preterm birth and low birthweight were associated with perinatal mortality. Marriage and caesarean section were protective.Conclusions
Twin pregnancy is a significant risk factor for maternal and perinatal morbidity and mortality in low-resource settings; maternal risk and access to safe caesarean section may determine safest mode of delivery in LMICs. Improving obstetric care in twin pregnancies, particularly timely access to safe caesarean section, is required to reduce risk to mother and baby. 相似文献85.
Ronan A. Lyons Denise Kendrick Elizabeth M. L. Towner Carol Coupland Mike Hayes Nicola Christie Judith Sleney Sarah Jones Richard Kimberlee Sarah E. Rodgers Samantha Turner Mariana Brussoni Yana Vinogradova Tinnu Sarvotham Steven Macey 《PloS one》2013,8(4)
Objective
To determine whether advocacy targeted at local politicians leads to action to reduce the risk of pedestrian injury in deprived areas.Design
Cluster randomised controlled trial.Setting
239 electoral wards in 57 local authorities in England and Wales.Participants
617 elected local politicians.Interventions
Intervention group politicians were provided with tailored information packs, including maps of casualty sites, numbers injured and a synopsis of effective interventions.Main outcome measures
25–30 months post intervention, primary outcomes included: electoral ward level: percentage of road traffic calmed; proportion with new interventions; school level: percentage with 20 mph zones, Safe Routes to School, pedestrian training or road safety education; politician level: percentage lobbying for safety measures. Secondary outcomes included politicians’ interest and involvement in injury prevention, and facilitators and barriers to implementation.Results
Primary outcomes did not significantly differ: % difference in traffic calming (0.07, 95%CI: −0.07 to 0.20); proportion of schools with 20 mph zones (RR 1.47, 95%CI: 0.93 to 2.32), Safe Routes to School (RR 1.34, 95%CI: 0.83 to 2.17), pedestrian training (RR 1.23, 95%CI: 0.95 to 1.61) or other safety education (RR 1.16, 95%CI: 0.97 to 1.39). Intervention group politicians reported greater interest in child injury prevention (RR 1.09, 95%CI 1.03 to 1.16), belief in potential to help prevent injuries (RR 1.36, 95%CI 1.16 to 1.61), particularly pedestrian safety (RR 1.55, 95%CI 1.19 to 2.03). 63% of intervention politicians reported supporting new pedestrian safety schemes. The majority found the advocacy information surprising, interesting, effectively presented, and could identify suitable local interventions.Conclusions
This study demonstrates the feasibility of an innovative approach to translational public health by targeting local politicians in a randomised controlled trial. The intervention package was positively viewed and raised interest but changes in interventions were not statistically significance. Longer term supported advocacy may be needed.Trial Registration
Current Controlled Trials ISRCTN91381117 相似文献86.
Mariana D. Carrillo-Del Valle Jorge A. De la Garza-García Efrén Díaz-Aparicio Arturo G. Valdivia-Flores Luis F. Cisneros-Guzmán Cecilia Rosario Ángel H. Manjarrez-Hernández Armando Navarro Juan Xicohtencatl-Cortes Pablo Maravilla Rigoberto Hernández-Castro 《European Journal of Wildlife Research》2016,62(4):415-421
87.
Marcelo Magioli Katia Maria Paschoaletto Micchi de Barros Ferraz Eleonore Zulnara Freire Setz Alexandre Reis Percequillo Michelle Viviane de Sá Santos Rondon Vanessa Villanova Kuhnen Mariana Cristina da Silva Canhoto Karen Evelyn Almeida dos Santos Claudia Zukeran Kanda Gabriela de Lima Fregonezi Helena Alves do Prado Mitra Katherina Ferreira Milton Cezar Ribeiro Priscilla Marqui Schmidt Villela Luiz Lehmann Coutinho Márcia Gonçalves Rodrigues 《European Journal of Wildlife Research》2016,62(4):431-446
88.
Virginie Riou Debany Fonseca-Batista Arnout Roukaerts Isabelle C. Biegala Shree Ram Prakya Clara Magalh?es Loureiro Mariana Santos Angel E. Muniz-Piniella Mara Schmiing Marc Elskens Natacha Brion M. Ana Martins Frank Dehairs 《PloS one》2016,11(3)
To understand the impact of the northwestern Azores Current Front (NW-AzC/AzF) system on HCO3−-and N2-fixation activities and unicellular diazotrophic cyanobacteria (UCYN) distribution, we combined geochemical and biological approaches from the oligotrophic surface to upper mesopelagic waters. N2-fixation was observed to sustain 45–85% of the HCO3−-fixation in the picoplanktonic fraction performing 47% of the total C-fixation at the deep chlorophyll maximum north and south of the AzF. N2-fixation rates as high as 10.9 μmol N m-3 d-1 and surface nitrate δ15N as low as 2.7‰ were found in the warm (18–24°C), most saline (36.5–37.0) and least productive waters south of the AzF, where UCYN were the least abundant. However, picoplanktonic UCYN abundances up to 55 cells mL-1 were found at 45–200m depths in the coolest nutrient-rich waters north of the AzF. In this area, N2-fixation rates up to 4.5 μmol N m-3 d-1 were detected, associated with depth-integrated H13CO3−-fixation rates at least 50% higher than observed south of the AzF. The numerous eddies generated at the NW-AzC/AzF seem to enhance exchanges of plankton between water masses, as well as vertical and horizontal diapycnal diffusion of nutrients, whose increase probably enhances the growth of diazotrophs and the productivity of C-fixers. 相似文献
89.