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1.
Stroke ; 55(2): 278-287, 2024 02.
Artigo em Inglês | MEDLINE | ID: mdl-38252759

RESUMO

BACKGROUND: The association between sex and outcome after endovascular thrombectomy of acute ischemic stroke is unclear. The aim of this study was to compare the clinical and safety outcomes between men and women treated with endovascular thrombectomy in the late 6-to-24-hour window period. METHODS: This multicenter, retrospective observational cohort study included consecutive patients who underwent endovascular thrombectomy of anterior circulation stroke in the late window from 66 clinical sites in 10 countries from January 2014 to May 2022. The primary outcome was the 90-day ordinal modified Rankin Scale score. Secondary outcomes included 90-day functional independence (FI), return of Rankin (RoR) to prestroke baseline, FI or RoR, symptomatic intracranial hemorrhage, and mortality. Multivariable and inverse probability of treatment weighting methods were used. We explored the interaction of sex with baseline characteristics on the outcomes ordinal modified Rankin Scale and FI or RoR. RESULTS: Of 1932 patients, 1055 were women and 877 were men. Women were older (77 versus 69 years), had higher rates of atrial fibrillation, hypertension, and greater prestroke disability, but there was no difference in baseline National Institutes of Health Stroke Scale score. Inverse probability of treatment weighting analysis showed no difference between women and men in ordinal modified Rankin Scale (odds ratio, 0.98 [95% CI, 0.79-1.21]), FI or RoR (odds ratio, 0.98 [95% CI, 0.78-1.22]), severe disability or mortality (odds ratio, 0.99 [95% CI, 0.80-1.23]). The multivariable analysis of the above end points was concordant. There were no interactions between baseline characteristics and sex on the outcomes of ordinal modified Rankin Scale and FI or RoR. CONCLUSIONS: In late presenting patients with anterior circulation stroke treated with endovascular thrombectomy in the 6 to 24-hour window, there was no difference in clinical or safety outcomes between men and women.


Assuntos
Fibrilação Atrial , AVC Isquêmico , Acidente Vascular Cerebral , Estados Unidos , Humanos , Feminino , Masculino , Caracteres Sexuais , Estudos Retrospectivos , Acidente Vascular Cerebral/cirurgia
2.
Semin Neurol ; 43(3): 432-438, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37562456

RESUMO

Advances in robotic technology have improved standard techniques in numerous surgical and endovascular specialties, offering more precision, control, and better patient outcomes. Robotic-assisted interventional neuroradiology is an emerging field at the intersection of interventional neuroradiology and biomedical robotics. Endovascular robotics can automate maneuvers to reduce procedure times and increase its safety, reduce occupational hazards associated with ionizing radiations, and expand networks of care to reduce gaps in geographic access to neurointerventions. To date, many robotic neurointerventional procedures have been successfully performed, including cerebral angiography, intracranial aneurysm embolization, carotid stenting, and epistaxis embolization. This review aims to provide a survey of the state of the art in robotic-assisted interventional neuroradiology, consider their technical and adoption limitations, and explore future developments critical for the widespread adoption of robotic-assisted neurointerventions.


Assuntos
Procedimentos Endovasculares , Aneurisma Intracraniano , Robótica , Humanos , Aneurisma Intracraniano/diagnóstico por imagem , Aneurisma Intracraniano/cirurgia , Procedimentos Endovasculares/métodos
3.
Small ; 18(33): e2203821, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35867042

RESUMO

2D layered molybdenum disulfide (MoS2 ) nanomaterials are a promising platform for biomedical applications, particularly due to its high biocompatibility characteristics, mechanical and electrical properties, and flexible functionalization. Additionally, the bandgap of MoS2 can be engineered to absorb light over a wide range of wavelengths, which can then be transformed into local heat for applications in photothermal tissue ablation and regeneration. However, limitations such as poor stability of aqueous dispersions and low accumulation in affected tissues impair the full realization of MoS2 for biomedical applications. To overcome such challenges, herein, multifunctional MoS2 -based magnetic helical microrobots (MoSBOTs) using cyanobacterium Spirulina platensis are proposed as biotemplate for therapeutic and biorecognition applications. The cytocompatible microrobots combine remote magnetic navigation with MoS2 photothermal activity under near-infrared irradiation. The resulting photoabsorbent features of the MoSBOTs are exploited for targeted photothermal ablation of cancer cells and on-the-fly biorecognition in minimally invasive oncotherapy applications. The proposed multi-therapeutic MoSBOTs hold considerable potential for a myriad of cancer treatment and diagnostic-related applications, circumventing current challenges of ablative procedures.


Assuntos
Molibdênio , Nanoestruturas , Dissulfetos , Raios Infravermelhos , Fototerapia/métodos
4.
BMC Med Res Methodol ; 20(1): 228, 2020 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-32917141

RESUMO

BACKGROUND: COVID-19, the disease caused by the highly infectious and transmissible coronavirus SARS-CoV-2, has quickly become a morbid global pandemic. Although the impact of SARS-CoV-2 infection in children is less clinically apparent, collecting high-quality biospecimens from infants, children, and adolescents in a standardized manner during the COVID-19 pandemic is essential to establish a biologic understanding of the disease in the pediatric population. This biorepository enables pediatric centers world-wide to collect samples uniformly to drive forward our understanding of COVID-19 by addressing specific pediatric and neonatal COVID-19-related questions. METHODS: A COVID-19 biospecimen collection study was implemented with strategic enrollment guidelines to include patients seen in urgent care clinics and hospital settings, neonates born to SARS-CoV-2 infected mothers, and asymptomatic children. The methodology described here, details the importance of establishing collaborations between the clinical and research teams to harmonize protocols for patient recruitment and sample collection, processing and storage. It also details modifications required for biobanking during a surge of the COVID-19 pandemic. RESULTS: Considerations and challenges facing enrollment of neonatal and pediatric cohorts are described. A roadmap is laid out for successful collection, processing, storage and database management of multiple pediatric samples such as blood, nasopharyngeal and oropharyngeal swabs, sputum, saliva, tracheal aspirates, stool, and urine. Using this methodology, we enrolled 327 participants, who provided a total of 972 biospecimens. CONCLUSIONS: Pediatric biospecimens will be key in answering questions relating to viral transmission by children, differences between pediatric and adult viral susceptibility and immune responses, the impact of maternal SARS-CoV-2 infection on fetal development, and factors driving the Multisystem Inflammatory Syndrome in Children. The specimens in this biorepository will allow necessary comparative studies between children and adults, help determine the accuracy of current pediatric viral testing techniques, in addition to, understanding neonatal exposure to SARS-CoV-2 infection and disease abnormalities. The successful establishment of a pediatric biorepository is critical to provide insight into disease pathogenesis, and subsequently, develop future treatment and vaccination strategies.


Assuntos
Betacoronavirus , Infecções por Coronavirus/diagnóstico , Pneumonia Viral/diagnóstico , Manejo de Espécimes/métodos , Adolescente , COVID-19 , Criança , Pré-Escolar , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/transmissão , Feminino , Desenvolvimento Fetal , Hospitalização , Humanos , Lactente , Recém-Nascido , Masculino , Pandemias , Pneumonia Viral/imunologia , Pneumonia Viral/transmissão , SARS-CoV-2
5.
J Neurophysiol ; 122(1): 1-4, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-30864847

RESUMO

Cognitive impairment in older adults is associated with sleep and circadian rhythm disturbances. Numerous studies have linked disrupted sleep and circadian rhythms with amyloid-ß (Aß), a key pathological hallmark in Alzheimer's disease (AD). While previous evidence suggests that Aß initiates AD pathogenesis, tau, another major hallmark of AD, seems to drive neurodegeneration. Recent studies imply that sleep-wake cycles affect brain tau more significantly than Aß levels, leading to accelerated AD progression and cognitive decline. The study of sleep disturbances in AD is shedding light on our understanding of the mechanism underlying sleep disturbances in AD and dementia.


Assuntos
Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Transtornos do Sono-Vigília/metabolismo , Doença de Alzheimer/complicações , Animais , Ritmo Circadiano , Humanos , Transtornos do Sono-Vigília/etiologia , Proteínas tau/metabolismo
6.
Nanoscale ; 15(36): 14800-14808, 2023 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-37646185

RESUMO

Piezoelectric nanomaterials have become increasingly popular in the field of biomedical applications due to their high biocompatibility and ultrasound-mediated piezocatalytic properties. In addition, the ability of these nanomaterials to disaggregate amyloid proteins, which are responsible for a range of diseases resulting from the accumulation of these proteins in body tissues and organs, has recently gained considerable attention. However, the use of nanoparticles in biomedicine poses significant challenges, including targeting and uncontrolled aggregation. To address these limitations, our study proposes to load these functional nanomaterials on a multifunctional mobile microrobot (PiezoBOT). This microrobot is designed by coating magnetic and piezoelectric barium titanate nanoparticles on helical biotemplates, allowing for the combination of magnetic navigation and ultrasound-mediated piezoelectric effects to target amyloid disaggregation. Our findings demonstrate that acoustically actuated PiezoBOTs can effectively reduce the size of aggregated amyloid proteins by over 80% in less than 10 minutes by shortening and dissociating constituent amyloid fibrils. Moreover, the PiezoBOTs can be easily magnetically manipulated to actuate the piezocatalytic nanoparticles to specific amyloidosis-affected tissues or organs, minimizing side effects. These biocompatible PiezoBOTs offer a promising non-invasive therapeutic approach for amyloidosis diseases by targeting and breaking down protein aggregates at specific organ or tissue sites.


Assuntos
Amiloidose , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Nanopartículas , Humanos , Proteínas Amiloidogênicas , Fenômenos Magnéticos
7.
Chem Commun (Camb) ; 58(92): 12843-12846, 2022 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-36315253

RESUMO

In this report, we developed a photocatalyst-free visible-light-promoted deoxygenative alkylation of imines with alcohols assisted by carbon disulfide and tricyclohexylphosphine. The key to success of this method is the activation of alcohols upon the formation and direct photoexcitation of xanthate anions. This one-pot protocol enables the selective C-O bond homolysis of diverse primary, secondary and tertiary alcohols to react with a variety of N-sulfonyl and N-aryl imines, providing a general and efficient platform for α-branched amine synthesis from alcohols.

8.
Front Neurosci ; 16: 854992, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35401082

RESUMO

Alzheimer's disease (AD) is the most common cause of dementia in the elderly, clinically defined by progressive cognitive decline and pathologically, by brain atrophy, neuroinflammation, and accumulation of extracellular amyloid plaques and intracellular neurofibrillary tangles. Neurotechnological approaches, including optogenetics and deep brain stimulation, have exploded as new tools for not only the study of the brain but also for application in the treatment of neurological diseases. Here, we review the current state of AD therapeutics and recent advancements in both invasive and non-invasive neurotechnologies that can be used to ameliorate AD pathology, including neurostimulation via optogenetics, photobiomodulation, electrical stimulation, ultrasound stimulation, and magnetic neurostimulation, as well as nanotechnologies employing nanovectors, magnetic nanoparticles, and quantum dots. We also discuss the current challenges in developing these neurotechnological tools and the prospects for implementing them in the treatment of AD and other neurodegenerative diseases.

9.
Nat Commun ; 11(1): 1377, 2020 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-32170138

RESUMO

The relationship between amyloid-ß (Aß) species and tau pathology in Alzheimer's disease (AD) is not fully understood. Here, we provide direct evidence that Aß42/40 ratio, not total Aß level, plays a critical role in inducing neurofibrillary tangles (NTFs) in human neurons. Using 3D-differentiated clonal human neural progenitor cells (hNPCs) expressing varying levels of amyloid ß precursor protein (APP) and presenilin 1 (PS1) with AD mutations, we show that pathogenic tau accumulation and aggregation are tightly correlated with Aß42/40 ratio. Roles of Aß42/40 ratio on tau pathology are also confirmed with APP transmembrane domain (TMD) mutant hNPCs, which display differential Aß42/40 ratios without mutant PS1. Moreover, naïve hNPCs co-cultured with APP TMD I45F (high Aß42/40) cells, not with I47F cells (low Aß42/40), develop robust tau pathology in a 3D non-cell autonomous cell culture system. These results emphasize the importance of reducing the Aß42/40 ratio in AD therapy.


Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Técnicas de Cultura de Células/métodos , Neurônios/metabolismo , Neurônios/patologia , Fragmentos de Peptídeos/metabolismo , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/genética , Peptídeos beta-Amiloides/genética , Células Cultivadas , Técnicas de Cocultura , Humanos , Mutação , Células-Tronco Neurais/metabolismo , Fragmentos de Peptídeos/genética , Presenilina-1/genética , Presenilina-1/metabolismo
10.
Res Sq ; 2020 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-32818214

RESUMO

Background: COVID-19, the disease caused by the highly infectious and transmissible coronavirus SARS-CoV-2, has quickly become a morbid global pandemic. Although the impact of SARS-CoV-2 infection in children is less clinically apparent, collecting high-quality biospecimens from infants, children, and adolescents in a standardized manner during the COVID-19 pandemic is essential to establish a biologic understanding of the disease in the pediatric population. This biorepository enables pediatric centers world-wide to collect samples uniformly to drive forward our understanding of COVID-19 by addressing specific pediatric and neonatal COVID-19-related questions. Methods: A COVID-19 biospecimen collection study was implemented with strategic enrollment guidelines to include patients seen in urgent care clinics and hospital settings, neonates born to SARS-CoV-2 infected mothers, and asymptomatic children. The methodology described here, details the importance of establishing collaborations between the clinical and research teams to harmonize protocols for patient recruitment and sample collection, processing and storage. It also details modifications required for biobanking during a surge of the COVID-19 pandemic. Results: Considerations and challenges facing enrollment of neonatal and pediatric cohorts are described. A roadmap is laid out for successful collection, processing, storage and database management of multiple pediatric samples such as blood, nasopharyngeal and oropharyngeal swabs, sputum, saliva, tracheal aspirates, stool, and urine. Using this methodology, we enrolled 327 participants, who provided a total of 972 biospecimens. Conclusions: Pediatric biospecimens will be key in answering questions relating to viral transmission by children, differences between pediatric and adult viral susceptibility and immune responses, the impact of maternal SARS-CoV-2 infection on fetal development, and factors driving the Multisystem Inflammatory Syndrome in Children. The specimens in this biorepository will allow necessary comparative studies between children and adults, help determine the accuracy of current pediatric viral testing techniques, in addition to, understanding neonatal exposure to SARS-CoV-2 infection and disease abnormalities. The successful establishment of a pediatric biorepository is critical to provide insight into disease pathogenesis, and subsequently, develop future treatment and vaccination strategies.

11.
Complement Ther Med ; 42: 37-41, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30670269

RESUMO

OBJECTIVE: To examine trends in type, frequency, and effectiveness of different modes of exercise in patients with Parkinson's Disease (PD). BACKGROUND: Exercise has been shown to improve symptoms in PD patients. Recent studies suggest that dance may be a particularly helpful exercise option. However, it remains unclear how the benefits of various forms of exercise compare to dance and to each other. Information on these trends can help inform future exercise programs for PD patients. METHOD: 55 PD patients completed a survey on their exercise frequency, the impact of exercise on their symptoms, and whether they exercise alone or in groups. 9 PD patients who attend dance therapy classes completed an extended survey with additional questions comparing the benefit of dance therapy to traditional forms of exercise. RESULTS: Of the 64 patients surveyed, 67% of patients exercised at least twice a week for at least 30 minutes at a time, and 28% of patients exercised alone only. Walking was most commonly reported (77%), followed by stretching (52%), and weights (28%). 97% of patients who exercised noted mitigation of their PD symptoms. Additionally, a significantly greater percentage of patients who exercised in groups reported symptomatic improvements compared to patients who only exercised alone (p = 0.03). CONCLUSION: More patients who participated in group exercise reported symptomatic improvement compared to those who exercised strictly alone. This suggests that the psychosocial and cognitive component of group therapy, such as dance, may confer additional benefits to PD patients.


Assuntos
Exercício Físico/fisiologia , Doença de Parkinson/fisiopatologia , Autorrelato/estatística & dados numéricos , Dançaterapia/estatística & dados numéricos , Dança/fisiologia , Dança/estatística & dados numéricos , Terapia por Exercício/estatística & dados numéricos , Humanos , Inquéritos e Questionários/estatística & dados numéricos
12.
Adv Mater Technol ; 4(3): 1800490, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-32010758

RESUMO

Long-term implantation of biomedical electronics into the human body enables advanced diagnostic and therapeutic functionalities. However, most long-term resident electronics devices require invasive procedures for implantation as well as a specialized receiver for communication. Here, a gastric resident electronic (GRE) system that leverages the anatomical space offered by the gastric environment to enable residence of an orally delivered platform of such devices within the human body is presented. The GRE is capable of directly interfacing with portable consumer personal electronics through Bluetooth, a widely adopted wireless protocol. In contrast to the passive day-long gastric residence achieved with prior ingestible electronics, advancement in multimaterial prototyping enables the GRE to reside in the hostile gastric environment for a maximum of 36 d and maintain ≈15 d of wireless electronics communications as evidenced by the studies in a porcine model. Indeed, the synergistic integration of reconfigurable gastric-residence structure, drug release modules, and wireless electronics could ultimately enable the next-generation remote diagnostic and automated therapeutic strategies.

13.
Adv Healthc Mater ; 7(17): e1800417, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30004185

RESUMO

Recent advances in 3D printing have enabled the creation of novel 3D constructs and devices with an unprecedented level of complexity, properties, and functionalities. In contrast to manufacturing techniques developed for mass production, 3D printing encompasses a broad class of fabrication technologies that can enable 1) the creation of highly customized and optimized 3D physical architectures from digital designs; 2) the synergistic integration of properties and functionalities of distinct classes of materials to create novel hybrid devices; and 3) a biocompatible fabrication approach that facilitates the creation and cointegration of biological constructs and systems. This progress report describes how these capabilities can potentially address a myriad of unmet clinical needs. First, the creation of 3D-printed prosthetics to regain lost functionalities by providing structural support for skeletal and tubular organs is highlighted. Second, novel drug delivery strategies aided by 3D-printed devices are described. Third, the advancement of medical research heralded by 3D-printed tissue/organ-on-chips systems is discussed. Fourth, the developments of 3D-printed tissue and organ regeneration are explored. Finally, the potential for seamless integration of engineered organs with active devices by leveraging the versatility of multimaterial 3D printing is envisioned.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Impressão Tridimensional , Administração Oral , Regeneração Óssea/fisiologia , Humanos , Regeneração Nervosa/fisiologia , Engenharia Tecidual/métodos
14.
Medicine (Baltimore) ; 97(17): e0592, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29703056

RESUMO

RATIONALE: The treatment of granulomatosis with polyangiitis (GPA) with life-threatening complications, such as diffuse alveolar hemorrhage (DAH) and gastrointestinal hemorrhage (GIH), remains challenging. PATIENT CONCERNS: A 70-year-old female presented with a 6-month history of a productive cough and a 10-day history of arthralgia that progressed to respiratory failure and massive hematochezia. DIAGNOSES: Chest high-resolution computed tomography (HRCT) revealed multiple nodules, masses, and cavities. Urinalysis indicated microscopic hematuria. Test of proteinase3-anti-neutrophil cytoplasmic autoantibody (PR3-ANCA) was positive. INTERVENTIONS: The patient was transferred to the intensive care unit (ICU) and successfully treated with glucocorticoid pulse therapy and plasmapheresis. We combined mycophenolate mofetil (MMF) with glucocorticoid for maintenance treatment. OUTCOMES: The patient survived and is in a stable condition. We report this case that presented with a productive cough, followed by arthralgia, DAH, and GIH. LESSONS: Effective remission-induction therapy is a key to survival, while maintaining a balance between immunosuppression and avoiding infection is another challenge.


Assuntos
Hemorragia Gastrointestinal/terapia , Glucocorticoides/administração & dosagem , Granulomatose com Poliangiite/complicações , Hemorragia/terapia , Pneumopatias/terapia , Metilprednisolona/administração & dosagem , Plasmaferese/métodos , Idoso , Terapia Combinada , Feminino , Hemorragia Gastrointestinal/etiologia , Hemorragia/etiologia , Humanos , Pneumopatias/etiologia , Alvéolos Pulmonares
15.
Arch Bronconeumol ; 52(3): 138-44, 2016 Mar.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-26002550

RESUMO

INTRODUCTION: Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) readmission contributes considerably to the worse outcomes for COPD patients. Predictors for readmission include some socio-demographic variables and the severity of the underlying disease, however, few evidence suggested whether persistently heightened airway or systemic inflammation was related to recurrence of AECOPD. The aim of this study was to evaluate role of airway and systemic inflammatory biomarkers during AECOPD on predicting readmission for AECOPD. METHODS: Consecutive hospitalized patients with AECOPD were recruited. Inflammatory and clinical indices were evaluated at the day of admission before starting therapy and the day of planned discharge (day 10-14). Predictors for readmission were assessed by binary logistic regression model. RESULTS: 93 patients were included with 51 patients (54.8%) were readmitted due to AECOPD at least once during 1 year following the index admission. The logistic regression model indicated that age (OR=1.072, 95%CI: 1.012-1.135, P=.017), hs-CRP (high sensitive-C reactive protein) at day 14 (OR=1.392, 95%CI: 1.131-1.712, P=.002), CAT value at day 14 (OR=1.12, 95%CI: 1.031-1.217, P=.007) were the independent variables statistically significant in predicting rehospitalization. CONCLUSION: Systemic inflammatory marker CRP was a better predictor of readmission than sputum inflammatory markers. CAT score and age were also useful to predict readmission.


Assuntos
Mediadores da Inflamação/análise , Readmissão do Paciente/estatística & dados numéricos , Doença Pulmonar Obstrutiva Crônica/metabolismo , Escarro/química , Fatores Etários , Idoso , Biomarcadores/análise , Biomarcadores/sangue , Proteína C-Reativa/análise , Progressão da Doença , Feminino , Humanos , Contagem de Leucócitos , Masculino , Pessoa de Meia-Idade , Neutrófilos , Estudos Prospectivos , Doença Pulmonar Obstrutiva Crônica/terapia , Análise de Regressão , Fatores de Tempo
16.
Front Hum Neurosci ; 8: 853, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25414654

RESUMO

The relationship between working memory (WM) and attention is a highly interdependent one, with evidence that attention determines the state in which items in WM are retained. Through focusing of attention, an item might be held in a more prioritized state, commonly termed as the focus of attention (FOA). The remaining items, although still retrievable, are considered to be in a different representational state. One means to bring an item into the FOA is to use retrospective cues ("retro-cues") which direct attention to one of the objects retained in WM. Alternatively, an item can enter a privileged state once attention is directed towards it through bottom-up influences (e.g., recency effect) or by performing an action on one of the retained items ("incidental" cueing). In all these cases, the item in the FOA is recalled with better accuracy compared to the other items in WM. Far less is known about the nature of the other items in WM and whether they can be flexibly manipulated in and out of the FOA. We present data from three types of experiments as well as transcranial magnetic stimulation (TMS) to early visual cortex to manipulate the item inside FOA. Taken together, our results suggest that the context in which items are retained in WM matters. When an item remains behaviorally relevant, despite not being inside the FOA, re-focusing attention upon it can increase its recall precision. This suggests that a non-FOA item can be held in a state in which it can be later retrieved. However, if an item is rendered behaviorally unimportant because it is very unlikely to be probed, it cannot be brought back into the FOA, nor recalled with high precision. Under such conditions, some information appears to be irretrievably lost from WM. These findings, obtained from several different methods, demonstrate quite considerable flexibility with which items in WM can be represented depending upon context. They have important consequences for emerging state-dependent models of WM.

17.
Bioresour Technol ; 102(19): 9247-54, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21807503

RESUMO

Light olefins are the basic building blocks for the petrochemical industry. In this work, selective production of light olefins from catalytic cracking of bio-oil was performed by using the La/HZSM-5 catalyst. With a nearly complete conversion of bio-oil, the maximum yield reached 0.28±0.02 kg olefins/(kg bio-oil), which was close to that from methanol. Addition of La into zeolite efficiently changed the total acid amount of HZSM-5, especially the acid distribution among the strong, medium and weak acid sites. A moderate increase of the number of the medium acid sites effectively enhanced the olefins selectivity and improved the catalyst stability. The comparison between the catalytic cracking and pyrolysis of bio-oil was studied. The mechanism of the conversion of bio-oil to light olefins was also discussed.


Assuntos
Alcenos/síntese química , Óleos de Plantas/química , Alcenos/química , Catálise , Temperatura Alta , Lantânio/química , Espectroscopia de Ressonância Magnética , Modelos Químicos , Espectroscopia Fotoeletrônica , Difração de Raios X , Zeolitas/química
18.
Bioresour Technol ; 102(10): 6239-45, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21392976

RESUMO

A novel approach for high efficient conversion of the CO(2)-rich bio-syngas into the CO-rich bio-syngas was carried out by using biomass char and Ni/Al(2)O(3) catalyst, which was successfully applied for production of bio-methanol from bio-oil. After the bio-syngas conditioning, the CO(2)/CO ratio prominently dropped from 6.33 to 0.01-0.28. The maximum CO yield in the bio-syngas conditioning process reached about 1.96 mol/(mol CO(2)) with a nearly complete conversion of CO(2) (99.5%). The performance of bio-methanol synthesis was significantly improved via the conditioned bio-syngas, giving a maximum methanol yield of 1.32 kg/(kg(catalyst)h) with a methanol selectivity of 99%. Main reaction paths involved in the bio-syngas conditioning process have been investigated in detail by using different model mixture gases and different carbon sources.


Assuntos
Biomassa , Dióxido de Carbono/metabolismo , Metanol/metabolismo
19.
Anat Rec (Hoboken) ; 293(3): 414-20, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20169563

RESUMO

The hypoxic environment of solid tumor causes the tumor cells survive and which could protect them from death by facilitating resistance to therapy. Here, we provide evidence that hypoxia can increase tumor cell viability and proliferation through an Egr-1-dependant pathway. Hypoxia protected the microtubules from disassembly, and Egr-1 was colocalized with microtubules in different cell cycle stages. Knockdown of Egr-1 with its siRNA overcame the protection effect of hypoxia and increased the sensitivity of tumor cells to vinblastine under hypoxic conditions. Our results suggest a novel approach for increasing the sensitivity of tumor cells to chemotherapeutics that target microtubule assembly.


Assuntos
Antineoplásicos/farmacologia , Carcinoma Hepatocelular/tratamento farmacológico , Proteína 1 de Resposta de Crescimento Precoce/metabolismo , Hipóxia/metabolismo , Microtúbulos/metabolismo , Vimblastina/farmacologia , Western Blotting , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Proliferação de Células/efeitos dos fármacos , Proteína 1 de Resposta de Crescimento Precoce/antagonistas & inibidores , Proteína 1 de Resposta de Crescimento Precoce/genética , Imunofluorescência , Humanos , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , RNA Interferente Pequeno/farmacologia , Células Tumorais Cultivadas
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