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Search Results: 1 - 10 of 177509 matches for " E. Amaro Jr. "
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Particokinetics: computational analysis of the superparamagnetic iron oxide nanoparticles deposition process
Cárdenas WH, Mamani JB, Sibov TT, Caous CA, Amaro Jr E, Gamarra LF
International Journal of Nanomedicine , 2012, DOI: http://dx.doi.org/10.2147/IJN.S30074
Abstract: rticokinetics: computational analysis of the superparamagnetic iron oxide nanoparticles deposition process Original Research (2589) Total Article Views Authors: Cárdenas WH, Mamani JB, Sibov TT, Caous CA, Amaro Jr E, Gamarra LF Published Date June 2012 Volume 2012:7 Pages 2699 - 2712 DOI: http://dx.doi.org/10.2147/IJN.S30074 Received: 20 January 2012 Accepted: 03 March 2012 Published: 12 June 2012 Walter HZ Cárdenas, Javier B Mamani, Tatiana T Sibov, Cristofer A Caous, Edson Amaro Jr, Lionel F Gamarra Instituto do Cérebro, Hospital Israelita Albert Einstein, S o Paulo, Brazil Background: Nanoparticles in suspension are often utilized for intracellular labeling and evaluation of toxicity in experiments conducted in vitro. The purpose of this study was to undertake a computational modeling analysis of the deposition kinetics of a magnetite nanoparticle agglomerate in cell culture medium. Methods: Finite difference methods and the Crank-Nicolson algorithm were used to solve the equation of mass transport in order to analyze concentration profiles and dose deposition. Theoretical data were confirmed by experimental magnetic resonance imaging. Results: Different behavior in the dose fraction deposited was found for magnetic nanoparticles up to 50 nm in diameter when compared with magnetic nanoparticles of a larger diameter. Small changes in the dispersion factor cause variations of up to 22% in the dose deposited. The experimental data confirmed the theoretical results. Conclusion: These findings are important in planning for nanomaterial absorption, because they provide valuable information for efficient intracellular labeling and control toxicity. This model enables determination of the in vitro transport behavior of specific magnetic nanoparticles, which is also relevant to other models that use cellular components and particle absorption processes.
Retraction
Cárdenas WH, Mamani JB, Sibov TT, Caous CA, Amaro E Jr, Gamarra LF
International Journal of Nanomedicine , 2012, DOI: http://dx.doi.org/10.2147/IJN.S37825
Abstract: Retraction Retraction (1967) Total Article Views Authors: Cárdenas WH, Mamani JB, Sibov TT, Caous CA, Amaro E Jr, Gamarra LF Published Date September 2012 Volume 2012:7 Pages 5107 - 5108 DOI: http://dx.doi.org/10.2147/IJN.S37825 Received: 06 September 2012 Accepted: Published: 21 September 2012 Cárdenas WH, Mamani JB, Sibov TT, Caous CA, Amaro E Jr, Gamarra LF. Particokinetics: computational analysis of the superparamagnetic iron oxide nanoparticles deposition process. Int J Nanomedicine. 2012;7:2699–2712. It was brought to our attention that the Cárdenas et al paper did not cite a key source paper for the mathematics and approach to modeling the particokinetics of nanoparticles: Hinderliter PM, Minard KR, Orr O, et al. ISDD: A computational model of particle sedimentation, diffusion and target cell dosimetry for in vitro toxicity studies. Part Fibre Toxicol. 2010;7:36. In addition to unacceptable similarities in equations, computer implementation, and use of parameters from the above reference, three of the figures appearing in the paper are nearly identical to those published in the abovementioned Hinderliter et al, while others are very similar to those published in Teeguarden JG, Hinderliter PM, Orr G, Thrall BD, Pounds JG. Particokinetics in vitro: dosimetry considerations for in vitro nanoparticle toxicity assessments. Toxicol Sci. 2007;95(2) 300–312. A number of other relevant citations were not included: Bird RB, Stewart WE, Lightfoot EN. Transport Phenomena. 2nd edition. New York: John Wiley and Sons Inc; 2002:97. Socolofsky SA, Jirka GH. Environmental Fluid Mechanics Part I: Mass Transfer and Diffusion Engineering – Lectures. 2nd edition. Karlsruhe-Germany; 2002:23. Probstein RF. Physicochemical Hydrodynamics – An Introduction. 2nd Edition. New York: John Wiley and Sons Inc; 2003:45. Bejan A. Convection Heat Transfer. 3rd edition. New York: John Wiley and Sons Inc; 2004:515. We have no choice but to retract the publication by Cárdenas et al. Post to: Cannotea Citeulike Del.icio.us Facebook LinkedIn Twitter Other articles by Dr Tim Hill Erratum Readers of this article also read: Particokinetics: computational analysis of the superparamagnetic iron oxide nanoparticles deposition process Optical imaging to trace near infrared fluorescent zinc oxide nanoparticles following oral exposure Update on the management of ulcerative colitis: treatment and maintenance approaches focused on MMX mesalamine Targeted delivery of tissue plasminogen activator by binding to silica-coated magnetic nanoparticle Anti-CEA loaded maghemite nanoparticles as a theragnostic device for colorectal cancer Nucleocytoplasmic transport blockage by SV40 peptide-modified gold nanoparticles induces cellular autophagy Post intrastromal corneal ring segments insertion complicated by Candida parapsilosis keratitis Cancer stem cell theory: therapeutic implications for nanomedicine What are the roles of carers in decision-making for amyotrophic lateral sclerosis multidiscipl
Dopamine Transporter Density by [99mTc]-TRODAT-1 SPECT and Neurocognitive Performance - a preliminary pilot study.
Shih, Ming C. MD.,Amaro, Edson Jr. MD, PhD.,Souza, Sayuri de E,Pupo, Mariana C.
Alasbimn Journal , 2006,
Abstract: Introduction: Cognitive deficits are associated with functional impairment as well as with poor quality of life in Parkinson’s disease (PD). The main brain alteration in PD is a progressive loss of nigrostriatal dopamine neurons. Both animal and human studies have demonstrated that basal ganglia dopamine system is important for cognitive and motor functioning. Dopamine transporter (DAT) PET and SPECT radiotracers have been successfully used to estimate, in vivo, dopamine neuronal loss in humans.Objectives: The present study is aimed to examine the relationship between cognitive impairment and striatal dopamine neuronal loss, as estimated by [99mTc]-TRODAT-1 SPECT in PD patients.Methods: Fifteen PD patients were scanned with [99mTc]-TRODAT-1 SPECT (Dual-Head-SPECT Hwakeye, GE). SPECT images were reconstructed with FBP and Butterworth filter 0,40c/px order 10. Regions of interest (ROIs) were striatum (STR) and occipital lobe (BKG nonspecific binding) and were delineated in 3-mm transaxials slices analyzed according to this formula BP=([STR-BKG]/BKG), where BP is the striatal DAT binding potential. Neurocognitive tests, including the Rey Auditory Verbal Learning Test, Wisconsin Card Sorting Test, Ravens Progressive Matrices, Digit Span and Tavis 3, were applied to all subjects by trained neuropsychologists.Results: Striatal DAT binding potential (BP) was negatively correlated with the RAVLT tests 4 (R= 0.57, p<0.05) and 5 (R= 0.57, p<0.05), which evaluate verbal learning. Striatal DAT BP was also negatively correlated with the WCST learning item (R=0.54, p<0.05) and the Tavis 3 items, action error (R=0.52, p<0.05) and number of correct responses (R=0.47, p<0.05).Conclusions: Although preliminary, the present findings suggest that striatal DAT loss is associated with a poorer performance on verbal learning and cognitive flexibility tasks. These results are in line with a previous study that examined healthy volunteers and found a relationship between caudate DAT density and performance on verbal learning tasks. Caudate/putamen segmentation in a larger sample is being performed by this group and will potentially provide more information on the relationship between cognitive deficits and DAT loss.
Patterns of cerebral activation during lexical and phonological reading in Portuguese
Senaha, M.L.H.;Martin, M.G.M.;Amaro Jr., E.;Campi, C.;Caramelli, P.;
Brazilian Journal of Medical and Biological Research , 2005, DOI: 10.1590/S0100-879X2005001200013
Abstract: according to the concepts of cognitive neuropsychology, there are two principal routes of reading processing: a lexical route, in which global reading of words occurs and a phonological route, responsible for the conversion of the graphemes into their respective phonemes. in the present study, functional magnetic resonance imaging (fmri) was used to investigate the patterns of cerebral activation in lexical and phonological reading by 13 healthy women with a formal educational level greater than 11 years. participants were submitted to a silent reading task containing three types of stimuli: real words (irregular and foreign words), nonwords and illegitimate graphic stimuli. an increased number of activated voxels were identified by fmri in the word reading (lexical processing) than in the nonword reading (phonological processing) task. in word reading, activation was greater than for nonwords in the following areas: superior, middle and inferior frontal gyri, and bilateral superior temporal gyrus, right cerebellum and the left precentral gyrus, as indicated by fmri. in the reading of nonwords, the activation was predominant in the right cerebellum and in the left superior temporal gyrus. the results of the present study suggest the existence of differences in the patterns of cerebral activation during lexical and phonological reading, with greater involvement of the right hemisphere in reading words than nonwords.
Patterns of cerebral activation during lexical and phonological reading in Portuguese
Senaha M.L.H.,Martin M.G.M.,Amaro Jr. E.,Campi C.
Brazilian Journal of Medical and Biological Research , 2005,
Abstract: According to the concepts of cognitive neuropsychology, there are two principal routes of reading processing: a lexical route, in which global reading of words occurs and a phonological route, responsible for the conversion of the graphemes into their respective phonemes. In the present study, functional magnetic resonance imaging (fMRI) was used to investigate the patterns of cerebral activation in lexical and phonological reading by 13 healthy women with a formal educational level greater than 11 years. Participants were submitted to a silent reading task containing three types of stimuli: real words (irregular and foreign words), nonwords and illegitimate graphic stimuli. An increased number of activated voxels were identified by fMRI in the word reading (lexical processing) than in the nonword reading (phonological processing) task. In word reading, activation was greater than for nonwords in the following areas: superior, middle and inferior frontal gyri, and bilateral superior temporal gyrus, right cerebellum and the left precentral gyrus, as indicated by fMRI. In the reading of nonwords, the activation was predominant in the right cerebellum and in the left superior temporal gyrus. The results of the present study suggest the existence of differences in the patterns of cerebral activation during lexical and phonological reading, with greater involvement of the right hemisphere in reading words than nonwords.
Study of the ferrofluid drying process for morphological and nanostructutal characterization
Gamarra, L. F.;Brito, G. E. S. .;Pontuschka, W. M.;Mamani, J. B.;Moreira-Filho, C. A.;Amaro Jr., E.;
Brazilian Journal of Physics , 2007, DOI: 10.1590/S0103-97332007000800016
Abstract: a drying method suitable for the study of the morphological and structural properties of colloidal magnetic systems, including a contrast agent used in magnetic resonance imaging (mri) is described. we tested three alternative ferrofluid drying methods: drying at 70 70occ in nitrogen atmosphere; drying in air at 70 70occ; and drying by liophylization using an mri marker in the form of a colloidal suspension (endoremtm - guebert). x-ray diffraction (xrd), and transmission electron microscopy (tem) were applied to each characterization method. the xrd allowed the observation of the possible physical-chemical changes of the stabilizers and also fe3o4 present in the system. the morphology and nanoparticles size distribution was analyzed by tem. among the drying methods examined in this study, the liophylization has shown to be the more adequate one for the nanoparticles (fe3o4) morphological study and nanostructural characterization, because the structure of the nanoparticles was maintained the same as in the suspension. the drying procedures performed at 70 70occ in the atmospheres of nitrogen and air let to the coalescence and growth of the nanoparticles, as well as some degradation has been noticed in some of the stabilizers.
Application of hyperthermia induced by superparamagnetic iron oxide nanoparticles in glioma treatment
Silva AC, Oliveira TR, Mamani JB, Malheiros SMF, Malavolta L, Pavon LF, Sibov TT, Amaro E Jr, Tannús A, Vidoto ELG, Matins MJ, Santos RS, Gamarra LF
International Journal of Nanomedicine , 2011, DOI: http://dx.doi.org/10.2147/IJN.S14737
Abstract: pplication of hyperthermia induced by superparamagnetic iron oxide nanoparticles in glioma treatment Review (7971) Total Article Views Authors: Silva AC, Oliveira TR, Mamani JB, Malheiros SMF, Malavolta L, Pavon LF, Sibov TT, Amaro E Jr, Tannús A, Vidoto ELG, Matins MJ, Santos RS, Gamarra LF Published Date March 2011 Volume 2011:6 Pages 591 - 603 DOI: http://dx.doi.org/10.2147/IJN.S14737 André C Silva1, Tiago R Oliveira1,2, Javier B Mamani1, Suzana MF Malheiros3,4, Luciana Malavolta1, Lorena F Pavon1, Tatiana T Sibov1, Edson Amaro Jr1,5, Alberto Tannús6, Edson LG Vidoto6, Mateus J Martins6, Ricardo S Santos6, Lionel F Gamarra1 1Instituto Israelita de Ensino e Pesquisa Albert Einstein, IIEPAE, S o Paulo, Brazil; 2Instituto de Física, Universidade de S o Paulo, S o Paulo, Brazil; 3Departament of Neurology and Neurosurgery, Universidade Federal de S o Paulo, S o Paulo, Brazil; 4Neuro-Oncology Program of Hospital Israelita Albert Einstein, S o Paulo, Brazil; 5Instituto de Radiologia, Faculdade de Medicina; 6CIERMag-Instituto de Física de S o Carlos, Universidade de S o Paulo, S o Paulo, Brazil Abstract: Gliomas are a group of heterogeneous primary central nervous system (CNS) tumors arising from the glial cells. Malignant gliomas account for a majority of malignant primary CNS tumors and are associated with high morbidity and mortality. Glioblastoma is the most frequent and malignant glioma, and despite the recent advances in diagnosis and new treatment options, its prognosis remains dismal. New opportunities for the development of effective therapies for malignant gliomas are urgently needed. Magnetic hyperthermia (MHT), which consists of heat generation in the region of the tumor through the application of magnetic nanoparticles subjected to an alternating magnetic field (AMF), has shown positive results in both preclinical and clinical assays. The aim of this review is to assess the relevance of hyperthermia induced by magnetic nanoparticles in the treatment of gliomas and to note the possible variations of the technique and its implication on the effectiveness of the treatment. We performed an electronic search in the literature from January 1990 to October 2010, in various databases, and after application of the inclusion criteria we obtained a total of 15 articles. In vitro studies and studies using animal models showed that MHT was effective in the promotion of tumor cell death and reduction of tumor mass or increase in survival. Two clinical studies showed that MHT could be applied safely and with few side effects. Some studies suggested that mechanisms of cell death, such as apoptosis, necrosis, and antitumor immune response were triggered by MHT. Based on these data, we could conclude that MHT proved to be efficient in most of the experiments, and that the improvement of the nanocomposites as well as the AMF equipment might contribute toward establishing MHT as a promising tool in the treatment of malignant gliomas.
Faulty Suppression of Irrelevant Material in Patients with Thought Disorder Linked to Attenuated Frontotemporal Activation
S. M. Arcuri,M. R. Broome,V. Giampietro,E. Amaro Jr.,T. T. J. Kircher,S. C. R. Williams,C. M. Andrew,M. Brammer,R. G. Morris,P. K. McGuire
Schizophrenia Research and Treatment , 2012, DOI: 10.1155/2012/176290
Abstract: Formal thought disorder is a feature schizophrenia that manifests as disorganized, incoherent speech, and is associated with a poor clinical outcome. The neurocognitive basis of this symptom is unclear but it is thought to involve an impairment in semantic processing classically described as a loosening of meaningful associations. Using a paradigm derived from the n400 event-related, potential, we examined the extent to which regional activation during semantic processing is altered in schizophrenic patients with formal thought disorder. Ten healthy control and 18 schizophrenic participants (9 with and 9 without formal thought disorder) performed a semantic decision sentence task during an event-related functional magnetic resonance imaging experiment. We employed analysis of variance to estimate the main effects of semantic congruency and groups on activation and specific effects of formal thought disorder were addressed using post-hoc comparisons. We found that the frontotemporal network, normally engaged by a semantic decision task, was underactivated in schizophrenia, particularly in patients with FTD. This network is implicated in the inhibition of automatically primed stimuli and impairment of its function interferes with language processing and contributes to the production of incoherent speech.
Engagement of multifocal neural circuits during recall of autobiographical happy events
Cerqueira, C.T.;Almeida, J.R.C.;Gorenstein, C.;Gentil, V.;Leite, C.C.;Sato, J.R.;Amaro Jr., E.;Busatto, G.F.;
Brazilian Journal of Medical and Biological Research , 2008, DOI: 10.1590/S0100-879X2008001200006
Abstract: happy emotional states have not been extensively explored in functional magnetic resonance imaging studies using autobiographic recall paradigms. we investigated the brain circuitry engaged during induction of happiness by standardized script-driven autobiographical recall in 11 healthy subjects (6 males), aged 32.4 ± 7.2 years, without physical or psychiatric disorders, selected according to their ability to vividly recall personal experiences. blood oxygen level-dependent (bold) changes were recorded during auditory presentation of personal scripts of happiness, neutral content and negative emotional content (irritability). the same uniform structure was used for the cueing narratives of both emotionally salient and neutral conditions, in order to decrease the variability of findings. in the happiness relative to the neutral condition, there was an increased bold signal in the left dorsal prefrontal cortex and anterior insula, thalamus bilaterally, left hypothalamus, left anterior cingulate gyrus, and midportions of the left middle temporal gyrus (p < 0.05, corrected for multiple comparisons). relative to the irritability condition, the happiness condition showed increased activity in the left insula, thalamus and hypothalamus, and in anterior and midportions of the inferior and middle temporal gyri bilaterally (p < 0.05, corrected), varying in size between 13 and 64 voxels. findings of happiness-related increased activity in prefrontal and subcortical regions extend the results of previous functional imaging studies of autobiographical recall. the bold signal changes identified reflect general aspects of emotional processing, emotional control, and the processing of sensory and bodily signals associated with internally generated feelings of happiness. these results reinforce the notion that happiness induction engages a wide network of brain regions.
Faulty Suppression of Irrelevant Material in Patients with Thought Disorder Linked to Attenuated Frontotemporal Activation
S. M. Arcuri,M. R. Broome,V. Giampietro,E. Amaro Jr.,T. T. J. Kircher,S. C. R. Williams,C. M. Andrew,M. Brammer,R. G. Morris,P. K. McGuire
Schizophrenia Research and Treatment , 2012, DOI: 10.1155/2012/176290
Abstract: Formal thought disorder is a feature schizophrenia that manifests as disorganized, incoherent speech, and is associated with a poor clinical outcome. The neurocognitive basis of this symptom is unclear but it is thought to involve an impairment in semantic processing classically described as a loosening of meaningful associations. Using a paradigm derived from the n400 event-related, potential, we examined the extent to which regional activation during semantic processing is altered in schizophrenic patients with formal thought disorder. Ten healthy control and 18 schizophrenic participants (9 with and 9 without formal thought disorder) performed a semantic decision sentence task during an event-related functional magnetic resonance imaging experiment. We employed analysis of variance to estimate the main effects of semantic congruency and groups on activation and specific effects of formal thought disorder were addressed using post-hoc comparisons. We found that the frontotemporal network, normally engaged by a semantic decision task, was underactivated in schizophrenia, particularly in patients with FTD. This network is implicated in the inhibition of automatically primed stimuli and impairment of its function interferes with language processing and contributes to the production of incoherent speech. 1. Introduction Bleuler’s work in psychosis continues to be highly influential in furthering understanding of the signs and symptoms of schizophrenia [1]. Nevertheless, one of his primary conceptual contributions in understanding schizophrenia, “disturbance of associations” [2, 3], remains to be explained in terms of underlying neural basis. In turn, Bleuler’s ideas were influenced by Jung’s word association task [4]. Regardless of the psychological or affective mechanisms that may influence the production of speech, Jungian word association is by nature a semantic association test. Interpretations of the broader meanings of “split mind” and “association”, arising from the psychoanalytical field, are not incompatible with an inbuilt characteristic of this test, which taps into the concept of semantic priming [5], extensively investigated in schizophrenia (see Minzenberg et al. [6] for a review in single-word semantic priming in schizophrenia). However, some studies do not take into account specific symptoms proposed by Bleuler, such as formal thought disorder, as an underlying factor that would interfere with task performance (e.g., [7]), mixing up performance of patients with a range of distinct symptoms. Of note, there is a line of investigation
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