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1.
Adv Mind Body Med ; 28(1): 9-14, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38787681

RESUMO

Context: Healthy lifestyle practices among young adults are vital in preventing the deterioration of quality of life and mental health disorders. Tele-yoga can be a tool to reduce stress and promote healthy lifestyle behaviors but there are barriers to its wide-scale applications. Aim: This study aims to identify barriers to implementing tele-yoga intervention for stress management among post-graduate university students studying management in Bengaluru, India. Settings and Design: 55 university students, aged 20 - 30 years, who dropped out within one month from a free 45-minute tele-yoga program offered by the college were enrolled. Out of these dropouts, 38 consenting participants were interviewed individually to understand the barriers to completing tele-yoga program. Methods: A qualitative study was designed with an individual one-on-one interview to gain an in-depth understanding of barriers to tele-yoga practice. A thematic representation of the discussion was arrived at. The barrier score for each concern was computed by adding the count of responses which was then converted to percentile. Results: Out of 12 barriers, stress due to exams (34%) was the top-most barrier followed by time constraints (26%), network issues (9%), issues waking up in the morning (7%), and space constraints (7%). Conclusion: Barriers to implementing tele-yoga intervention for stress management are predominant among young adults. Future tele-yoga studies in this population should consider addressing these barriers.


Assuntos
Pesquisa Qualitativa , Estresse Psicológico , Estudantes , Telemedicina , Yoga , Humanos , Estresse Psicológico/terapia , Adulto , Estudantes/psicologia , Adulto Jovem , Masculino , Feminino , Universidades
2.
Cell Stem Cell ; 28(8): 1397-1410.e4, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-34010628

RESUMO

NF1-associated malignant peripheral nerve sheath tumors (MPNSTs) are the major cause of mortality in neurofibromatosis. MPNSTs arise from benign peripheral nerve plexiform neurofibromas that originate in the embryonic neural crest cell lineage. Using reporter transgenes that label early neural crest lineage cells in multiple NF1 MPNST mouse models, we discover and characterize a rare MPNST cell population with stem-cell-like properties, including quiescence, that is essential for tumor initiation and relapse. Following isolation of these cells, we derive a cancer-stem-cell-specific gene expression signature that includes consensus embryonic neural crest genes and identify Nestin as a marker for the MPNST cell of origin. Combined targeting of cancer stem cells along with antimitotic chemotherapy yields effective tumor inhibition and prolongs survival. Enrichment of the cancer stem cell signature in cognate human tumors supports the generality and relevance of cancer stem cells to MPNST therapy development.


Assuntos
Neurofibromatose 1 , Neurofibrossarcoma , Animais , Modelos Animais de Doenças , Camundongos , Recidiva Local de Neoplasia , Neurofibromatose 1/genética
3.
Brain Struct Funct ; 224(8): 2603-2617, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31407103

RESUMO

The human eye movement network is a complex system that requires the integration of sensory, motor, attentional, and executive processes. Here, we review the neuroanatomy of the eye movement network with an emphasis on functional neuroimaging applications. We consolidate the literature into a concise resource designed to be immediately accessible and applicable to diverse research interests, and present the novel Functional Oculomotor System (FOcuS) Atlas-a tool in stereotaxic space that will simplify and standardize the inclusion of the eye movement network in future functional neuroimaging studies. We anticipate this review and the FOcuS Atlas will facilitate increased examination of the eye movement network across disciplines leading to a thorough understanding of how eye movement network function contributes to higher-order cognition and how it is integrated with other brain networks. Furthermore, functional examination of the eye movement network in patient populations offers the potential for deeper insight into the role of eye movement circuitry in functional network activity, diagnostic assessments, and the indications for augmentative communication systems that rely on eye movement control.


Assuntos
Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Movimentos Oculares , Atlas como Assunto , Encéfalo/diagnóstico por imagem , Neuroimagem Funcional , Humanos , Vias Neurais/fisiologia
4.
Nature ; 567(7748): 341-346, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30842654

RESUMO

Cancer-specific inhibitors that reflect the unique metabolic needs of cancer cells are rare. Here we describe Gboxin, a small molecule that specifically inhibits the growth of primary mouse and human glioblastoma cells but not that of mouse embryonic fibroblasts or neonatal astrocytes. Gboxin rapidly and irreversibly compromises oxygen consumption in glioblastoma cells. Gboxin relies on its positive charge to associate with mitochondrial oxidative phosphorylation complexes in a manner that is dependent on the proton gradient of the inner mitochondrial membrane, and it inhibits the activity of F0F1 ATP synthase. Gboxin-resistant cells require a functional mitochondrial permeability transition pore that regulates pH and thus impedes the accumulation of Gboxin in the mitochondrial matrix. Administration of a metabolically stable Gboxin analogue inhibits glioblastoma allografts and patient-derived xenografts. Gboxin toxicity extends to established human cancer cell lines of diverse organ origin, and shows that the increased proton gradient and pH in cancer cell mitochondria is a mode of action that can be targeted in the development of antitumour reagents.


Assuntos
Glioblastoma/tratamento farmacológico , Glioblastoma/metabolismo , Fosforilação Oxidativa/efeitos dos fármacos , Aloenxertos , Animais , Astrócitos/citologia , Astrócitos/efeitos dos fármacos , Linhagem Celular Tumoral , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Camundongos , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Membranas Mitocondriais/efeitos dos fármacos , Membranas Mitocondriais/enzimologia , Membranas Mitocondriais/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Transplante de Neoplasias , Especificidade de Órgãos , Força Próton-Motriz/efeitos dos fármacos , ATPases Translocadoras de Prótons/antagonistas & inibidores , ATPases Translocadoras de Prótons/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
5.
J Synchrotron Radiat ; 26(Pt 2): 565-570, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30855269

RESUMO

SyLMAND, the Synchrotron Laboratory for Micro and Nano Devices, is a recently commissioned microfabrication bend magnet beamline with ancillary cleanroom facilities at the Canadian Light Source. The synchrotron radiation is applied to pattern high-aspect-ratio polymer microstructures used in the area of micro-electro-mechanical systems (MEMS). SyLMAND particularly focuses on spectral and beam power adjustability and large exposable area formats in an inert gas atmosphere; a rotating-disk intensity chopper allows for independent beam-power reduction, while continuous spectral tuning between 1-2 keV and >15 keV photon energies is achieved using a double-mirror system and low-atomic-number filters. Homogeneous exposure of samples up to six inches in diameter is performed in the experimental endstation, a vertically scanning precision stage (scanner) with tilt and rotation capabilities under 100 mbar helium. Commissioning was completed in late 2017, and SyLMAND is currently ramping up its user program, mostly in the areas of RF MEMS, micro-fluidics/life sciences and micro-optics.

6.
Rev Sci Instrum ; 89(11): 115001, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30501345

RESUMO

X-ray masks are indispensable tools in deep X-ray lithography (XRL). To date, hardly any fabrication technology can provide affordable and readily available masks with good structure quality. The bottleneck of adequate masks to a large extent limits the widespread use of XRL. In this article, an alternative XRL mask fabrication process is described to significantly improve availability and cost efficiency of XRL masks as key instruments in XRL processing: A 355 nm UV-laser is applied to expose SU-8 resist on an antireflective coating and a copper sacrificial substrate. The voids in this resist template are filled by a two-step electroplating process with sacrificial nickel and 3.6 µm thick gold absorbers. A second SU-8 coat embeds the absorbers, forming the 40 µm mask membrane. This configuration allows for XRL into resists of up to about 200 µm thickness at the SyLMAND beamline, Canada. The absorber structure accuracy is about 1 µm, at smallest tested lateral dimensions of 2 µm isolated features and 500 nm details. Upon release from the substrate, the membrane locally deforms by up to 1.79 µm. PMMA microstructures patterned with such a mask have smooth and vertical sidewalls. The SyLMAND chopper allows one to limit thermal deformations during exposure to the micrometer range: At a beam power of 0.42 W, typical thermal deformations are 0.5 µm-1.4 µm, depending on the layout, and position inaccuracies are about 3.3 µm.

7.
Oncotarget ; 9(30): 21429-21443, 2018 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-29765550

RESUMO

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and the prognosis of HCC patients, especially those with metastasis, remains extremely poor. This is partly due to unclear molecular mechanisms underlying HCC metastasis. Our previous study indicates that MDM2 Binding Protein (MTBP) suppresses migration and metastasis of HCC cells. However, signaling pathways regulated by MTBP remain unknown. To identify metastasis-associated signaling pathways governed by MTBP, we have performed unbiased luciferase reporter-based signal array analyses and found that MTBP suppresses the activity of the ETS-domain transcription factor Elk-1, a downstream target of Erk1/2 MAP kinases. MTBP also inhibits phosphorylation of Elk-1 and decreases mRNA expression of Elk-1 target genes. Reduced Elk-1 activity is caused by inhibited nuclear translocation of phosphorylated Erk1/2 (p-Erk) by MTBP and subsequent inhibition of Elk-1 phosphorylation. We also reveal that MTBP inhibits the interaction of p-Erk with importin-7/RanBP7 (IPO7), an importin family member which shuttles p-Erk into the nucleus, by binding to IPO7. Moreover, high levels of MTBP in human HCC tissues are correlated with cytoplasmic localization of p-Erk1/2. Our study suggests that MTBP suppresses metastasis, at least partially, by down-modulating the Erk1/2-Elk-1 signaling pathway, thus identifying a novel regulatory mechanism of HCC metastasis by regulating the subcellular localization of p-Erk.

9.
PLoS One ; 12(6): e0179168, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28636657

RESUMO

OBJECTIVES: The tumor suppressor p53 plays a crucial role in the development of osteosarcoma. The primary objective of this study is to develop and optimize lipid based nanoparticle formulations that can carry siRNA and effectively silence mutant p53 in 318-1, a murine osteosarcoma cell line. METHODS: The nanoparticles were composed of a mixture of two lipids (cholesterol and DOTAP) and either PLGA or PLGA-PEG and prepared by using an EmulsiFlex-B3 high pressure homogenizer. A series of studies that include using different nanoparticles, different amount of siRNAs, cell numbers, incubation time, transfection media volume, and storage temperature was performed to optimize the gene silencing efficiency. KEY FINDINGS: Replacement of lipids by PLGA or PLGA-PEG decreased the particle size and overall cytotoxicity. Among all lipid-polymer nanoformulations, nanoparticles with 10% PLGA showed highest mutant p53 knockdown efficiency while maintaining higher cell viability when a nanoparticle to siRNA ratio equal to 6.8:0.66 and 75 nM siRNA was used. With long term storage the mutant p53 knockdown efficiency decreased to a greater extent. CONCLUSIONS: This study warrants a future evaluation of this formulation for gene silencing efficiency of mutant p53 in tissue culture and animal models for the treatment of osteosarcoma.


Assuntos
Neoplasias Ósseas/patologia , Inativação Gênica , Osteossarcoma/patologia , RNA Interferente Pequeno/genética , Proteína Supressora de Tumor p53/antagonistas & inibidores , Neoplasias Ósseas/genética , Neoplasias Ósseas/metabolismo , Sobrevivência Celular , Humanos , Mutação , Nanopartículas , Osteossarcoma/genética , Osteossarcoma/metabolismo , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
11.
Nat Commun ; 7: 13561, 2016 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-27886186

RESUMO

The ability of cancer cells to survive and grow in anchorage- and serum-independent conditions is well correlated with their aggressiveness. Here, using a human whole-genome shRNA library, we identify TMIGD3 isoform1 (i1) as a factor that suppresses this ability in osteosarcoma (OS) cells, mainly by inhibiting NF-κB activity. Knockdown of TMIGD3 increases proliferation, tumour formation and metastasis of OS cells. Overexpression of TMIGD3 isoform1 (i1), but not isoform3 (i3) which shares a common C-terminal region, suppresses these malignant properties. Adenosine A3 receptor (A3AR) having an identical N-terminal region shows similar biological profiles to TMIGD3 i1. Protein expression of TMIGD3 and A3AR is lower in human OS tissues than normal tissues. Mechanistically, TMIGD3 i1 and A3AR commonly inhibit the PKA-Akt-NF-κB axis. However, TMIGD3 i1 only partially rescues phenotypes induced by A3AR knockdown, suggesting the presence of distinct pathways. Our findings reveal an unappreciated role for TMIGD3 i1 as a suppressor of NF-κB activity and OS progression.


Assuntos
Neoplasias Ósseas/patologia , Neoplasias Pulmonares/patologia , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana/metabolismo , NF-kappa B/metabolismo , Osteossarcoma/patologia , Receptor A3 de Adenosina/metabolismo , Animais , Neoplasias Ósseas/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Progressão da Doença , Regulação Neoplásica da Expressão Gênica , Técnicas de Silenciamento de Genes , Humanos , Pulmão/patologia , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/secundário , Glicoproteínas de Membrana/genética , Proteínas de Membrana/genética , Camundongos , Camundongos Nus , Osteossarcoma/genética , Osteossarcoma/secundário , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Interferência de RNA , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Receptor A3 de Adenosina/genética , Transdução de Sinais/genética , Ensaios Antitumorais Modelo de Xenoenxerto
12.
Nat Cell Biol ; 18(11): 1233-1243, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27775703

RESUMO

Stabilization of mutant p53 (mutp53) in tumours greatly contributes to malignant progression. However, little is known about the underlying mechanisms and therapeutic approaches to destabilize mutp53. Here, through high-throughput screening we identify statins, cholesterol-lowering drugs, as degradation inducers for conformational or misfolded p53 mutants with minimal effects on wild-type p53 (wtp53) and DNA contact mutants. Statins preferentially suppress mutp53-expressing cancer cell growth. Specific reduction of mevalonate-5-phosphate by statins or mevalonate kinase knockdown induces CHIP ubiquitin ligase-mediated nuclear export, ubiquitylation, and degradation of mutp53 by impairing interaction of mutp53 with DNAJA1, a Hsp40 family member. Knockdown of DNAJA1 also induces CHIP-mediated mutp53 degradation, while its overexpression antagonizes statin-induced mutp53 degradation. Our study reveals that DNAJA1 controls the fate of misfolded mutp53, provides insights into potential strategies to deplete mutp53 through the mevalonate pathway-DNAJA1 axis, and highlights the significance of p53 status in impacting statins' efficacy on cancer therapy.


Assuntos
Movimento Celular/genética , Proteínas de Choque Térmico HSP40/metabolismo , Mutação/genética , Proteína Supressora de Tumor p53/metabolismo , Linhagem Celular Tumoral , Transformação Celular Neoplásica/efeitos dos fármacos , Transformação Celular Neoplásica/genética , DNA/metabolismo , Humanos , Ácido Mevalônico/farmacologia , Ligação Proteica/genética , Proteína Supressora de Tumor p53/genética , Ubiquitinação
13.
Oncotarget ; 7(5): 5401-15, 2016 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-26700961

RESUMO

Many p53 hotspot mutants not only lose the transcriptional activity, but also show dominant-negative (DN) and oncogenic gain-of-function (GOF) activities. Increasing evidence indicates that knockdown of mutant p53 (mutp53) in cancer cells reduces their aggressive properties, suggesting that survival and proliferation of cancer cells are, at least partially, dependent on the presence of mutp53. However, these p53 siRNAs can downregulate both wild-type p53 (wtp53) and mutp53, which limits their therapeutic applications. In order to specifically deplete mutp53, we have developed allele-specific siRNAs against p53 hotspot mutants and validated their biological effects in the absence or presence of wtp53. First, the mutp53-specific siRNAs selectively reduced protein levels of matched p53 mutants with minimal reduction in wtp53 levels. Second, downregulation of mutp53 in cancer cells expressing a mutp53 alone (p53mut) resulted in significantly decreased cell proliferation and migration. Third, transfection of mutp53-specific siRNAs in cancer cells expressing both wtp53 and mutp53 also reduced cell proliferation and migration with increased transcripts of p53 downstream target genes, which became further profound when cells were treated with an MDM2 inhibitor Nutlin-3a or a chemotherapeutic agent doxorubicin. These results indicate that depletion of mutp53 by its specific siRNA restored endogenous wtp53 activity in cells expressing both wtp53 and mutp53. This is the first study demonstrating biological effects and therapeutic potential of allele-specific silencing of mutp53 by mutp53-specific siRNAs in cancer cells expressing both wtp53 and mutp53, thus providing a novel strategy towards targeted cancer therapies.


Assuntos
Carcinogênese/patologia , Proteínas Mutantes/genética , Mutação/genética , Neoplasias/prevenção & controle , Proteína Supressora de Tumor p53/genética , Alelos , Animais , Apoptose , Western Blotting , Carcinogênese/genética , Adesão Celular , Movimento Celular , Proliferação de Células , Regulação para Baixo , Genes Dominantes , Humanos , Imidazóis/metabolismo , Técnicas Imunoenzimáticas , Camundongos , Neoplasias/genética , Neoplasias/patologia , Piperazinas/metabolismo , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células Tumorais Cultivadas
14.
Anal Biochem ; 486: 70-4, 2015 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26142221

RESUMO

Osteosarcoma, the most common type of primary bone cancer, is the second highest cause of cancer-related death in pediatric patients. To understand the mechanisms behind osteosarcoma progression and to discover novel therapeutic strategies for this disease, a reliable and appropriate mouse model is essential. For this purpose, osteosarcoma cells need to be injected into the bone marrow. Previously, the intratibial and intrafemoral injection methods were reported; however, the major drawback of these methods is the potential leakage of tumor cells from the injection site during or after these procedures. To overcome this, we have established an improved method to minimize leakage in an orthotopic mouse model of osteosarcoma. By taking advantage of the anatomical benefits of the femur with less bowing and larger medullary cavity than those of the tibia, osteosarcoma cells are injected directly into the femoral cavity following reaming of its intramedullary space. To prevent potential leakage of tumor cells during and after the surgery, the injection site is sealed with bone wax. This method requires a minor surgery of approximately 15min under anesthesia. Our established orthotopic osteosarcoma model could serve as a valuable and reliable tool for examining progression of various types of bone tumors.


Assuntos
Neoplasias Ósseas/patologia , Transformação Celular Neoplásica , Fêmur , Injeções/métodos , Osteossarcoma/patologia , Animais , Linhagem Celular Tumoral , Modelos Animais de Doenças , Humanos , Camundongos
15.
Dev Cogn Neurosci ; 11: 155-74, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25660033

RESUMO

One potential obstacle limiting our ability to clarify ADHD etiology is the heterogeneity within the disorder, as well as in typical samples. In this study, we utilized a community detection approach on 106 children with and without ADHD (aged 7-12 years), in order to identify potential subgroups of participants based on the connectivity of the reward system. Children with ADHD were compared to typically developing children within each identified community, aiming to find the community-specific ADHD characteristics. Furthermore, to assess how the organization in subgroups relates to behavior, we evaluated delay-discounting gradient and impulsivity-related temperament traits within each community. We found that discrete subgroups were identified that characterized distinct connectivity profiles in the reward system. Importantly, which connections were atypical in ADHD relative to the control children were specific to the community membership. Our findings showed that children with ADHD and typically developing children could be classified into distinct subgroups according to brain functional connectivity. Results also suggested that the differentiation in "functional" subgroups is related to specific behavioral characteristics, in this case impulsivity. Thus, combining neuroimaging data and community detection might be a valuable approach to elucidate heterogeneity in ADHD etiology and examine ADHD neurobiology.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Encéfalo/fisiopatologia , Comportamento Impulsivo , Rede Nervosa/fisiopatologia , Neuroimagem , Recompensa , Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Criança , Feminino , Humanos , Masculino , Temperamento
16.
JAMA Psychiatry ; 71(9): 1015-24, 2014 09.
Artigo em Inglês | MEDLINE | ID: mdl-25006969

RESUMO

IMPORTANCE: Psychiatric nosology is limited by behavioral and biological heterogeneity within existing disorder categories. The imprecise nature of current nosologic distinctions limits both mechanistic understanding and clinical prediction. We demonstrate an approach consistent with the National Institute of Mental Health Research Domain Criteria initiative to identify superior, neurobiologically valid subgroups with better predictive capacity than existing psychiatric categories for childhood attention-deficit/hyperactivity disorder (ADHD). OBJECTIVE: To refine subtyping of childhood ADHD by using biologically based behavioral dimensions (i.e., temperament), novel classification algorithms, and multiple external validators. DESIGN, SETTING, AND PARTICIPANTS: A total of 437 clinically well-characterized, community-recruited children, with and without ADHD, participated in an ongoing longitudinal study. Baseline data were used to classify children into subgroups based on temperament dimensions and examine external validators including physiological and magnetic resonance imaging measures. One-year longitudinal follow-up data are reported for a subgroup of the ADHD sample to address stability and clinical prediction. MAIN OUTCOMES AND MEASURES: Parent/guardian ratings of children on a measure of temperament were used as input features in novel community detection analyses to identify subgroups within the sample. Groups were validated using 3 widely accepted external validators: peripheral physiological characteristics (cardiac measures of respiratory sinus arrhythmia and pre-ejection period), central nervous system functioning (via resting-state functional connectivity magnetic resonance imaging), and clinical outcomes (at 1-year longitudinal follow-up). RESULTS: The community detection algorithm suggested 3 novel types of ADHD, labeled as mild (normative emotion regulation), surgent (extreme levels of positive approach-motivation), and irritable (extreme levels of negative emotionality, anger, and poor soothability). Types were independent of existing clinical demarcations including DSM-5 presentations or symptom severity. These types showed stability over time and were distinguished by unique patterns of cardiac physiological response, resting-state functional brain connectivity, and clinical outcomes 1 year later. CONCLUSIONS AND RELEVANCE: Results suggest that a biologically informed temperament-based typology, developed with a discovery-based community detection algorithm, provides a superior description of heterogeneity in the ADHD population than does any current clinical nosologic criteria. This demonstration sets the stage for more aggressive attempts at a tractable, biologically based nosology.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/classificação , Temperamento , Algoritmos , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Encéfalo/fisiopatologia , Estudos de Casos e Controles , Criança , Eletrocardiografia , Feminino , Neuroimagem Funcional , Frequência Cardíaca/fisiologia , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Arritmia Sinusal Respiratória/fisiologia , Inquéritos e Questionários
17.
PLoS One ; 9(3): e91322, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24642753

RESUMO

Clinical investigations of many neuropsychiatric disorders rely on the assumption that diagnostic categories and typical control samples each have within-group homogeneity. However, research using human neuroimaging has revealed that much heterogeneity exists across individuals in both clinical and control samples. This reality necessitates that researchers identify and organize the potentially varied patterns of brain physiology. We introduce an analytical approach for arriving at subgroups of individuals based entirely on their brain physiology. The method begins with Group Iterative Multiple Model Estimation (GIMME) to assess individual directed functional connectivity maps. GIMME is one of the only methods to date that can recover both the direction and presence of directed functional connectivity maps in heterogeneous data, making it an ideal place to start since it addresses the problem of heterogeneity. Individuals are then grouped based on similarities in their connectivity patterns using a modularity approach for community detection. Monte Carlo simulations demonstrate that using GIMME in combination with the modularity algorithm works exceptionally well--on average over 97% of simulated individuals are placed in the accurate subgroup with no prior information on functional architecture or group identity. Having demonstrated reliability, we examine resting-state data of fronto-parietal regions drawn from a sample (N = 80) of typically developing and attention-deficit/hyperactivity disorder (ADHD) -diagnosed children. Here, we find 5 subgroups. Two subgroups were predominantly comprised of ADHD, suggesting that more than one biological marker exists that can be used to identify children with ADHD based from their brain physiology. Empirical evidence presented here supports notions that heterogeneity exists in brain physiology within ADHD and control samples. This type of information gained from the approach presented here can assist in better characterizing patients in terms of outcomes, optimal treatment strategies, potential gene-environment interactions, and the use of biological phenomenon to assist with mental health.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Lobo Frontal/fisiopatologia , Modelos Estatísticos , Vias Neurais/fisiopatologia , Lobo Parietal/fisiopatologia , Transtorno do Deficit de Atenção com Hiperatividade/genética , Biomarcadores/análise , Mapeamento Encefálico , Estudos de Casos e Controles , Criança , Simulação por Computador , Feminino , Interação Gene-Ambiente , Heterogeneidade Genética , Humanos , Imageamento por Ressonância Magnética , Masculino , Características de Residência
18.
PLoS One ; 9(2): e88297, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24505468

RESUMO

Recent studies using Magnetic Resonance Imaging (MRI) have proposed that the brain's white matter is organized as a rich club, whereby the most highly connected regions of the brain are also highly connected to each other. Here we use both functional and diffusion-weighted MRI in the human brain to investigate whether the rich club phenomena is present with functional connectivity, and how this organization relates to the structural phenomena. We also examine whether rich club regions serve to integrate information between distinct brain systems, and conclude with a brief investigation of the developmental trajectory of rich-club phenomena. In agreement with prior work, both adults and children showed robust structural rich club organization, comprising regions of the superior medial frontal/dACC, medial parietal/PCC, insula, and inferior temporal cortex. We also show that these regions were highly integrated across the brain's major networks. Functional brain networks were found to have rich club phenomena in a similar spatial layout, but a high level of segregation between systems. While no significant differences between adults and children were found structurally, adults showed significantly greater functional rich club organization. This difference appeared to be driven by a specific set of connections between superior parietal, insula, and supramarginal cortex. In sum, this work highlights the existence of both a structural and functional rich club in adult and child populations with some functional changes over development. It also offers a potential target in examining atypical network organization in common developmental brain disorders, such as ADHD and Autism.


Assuntos
Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Rede Nervosa/anatomia & histologia , Rede Nervosa/fisiologia , Adulto , Mapeamento Encefálico , Criança , Imagem de Tensor de Difusão , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Modelos Anatômicos , Modelos Neurológicos , Vias Neurais , Adulto Jovem
19.
Neuroimage ; 75: 165-175, 2013 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-23501054

RESUMO

Resting state functional connectivity MRI (rs-fcMRI) is a popular technique used to gauge the functional relatedness between regions in the brain for typical and special populations. Most of the work to date determines this relationship by using Pearson's correlation on BOLD fMRI timeseries. However, it has been recognized that there are at least two key limitations to this method. First, it is not possible to resolve the direct and indirect connections/influences. Second, the direction of information flow between the regions cannot be differentiated. In the current paper, we follow-up on recent work by Smith et al. (2011), and apply PC algorithm to both simulated data and empirical data to determine whether these two factors can be discerned with group average, as opposed to single subject, functional connectivity data. When applied on simulated individual subjects, the algorithm performs well determining indirect and direct connection but fails in determining directionality. However, when applied at group level, PC algorithm gives strong results for both indirect and direct connections and the direction of information flow. Applying the algorithm on empirical data, using a diffusion-weighted imaging (DWI) structural connectivity matrix as the baseline, the PC algorithm outperformed the direct correlations. We conclude that, under certain conditions, the PC algorithm leads to an improved estimate of brain network structure compared to the traditional connectivity analysis based on correlations.


Assuntos
Algoritmos , Encéfalo/fisiologia , Interpretação de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Vias Neurais/fisiologia , Adulto , Teorema de Bayes , Feminino , Humanos , Masculino
20.
Eur Neuropsychopharmacol ; 23(1): 33-45, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23206930

RESUMO

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent psychiatric disorder that has poor long-term outcomes and remains a major public health concern. Recent theories have proposed that ADHD arises from alterations in multiple neural pathways. Alterations in reward circuits are hypothesized as one core dysfunction, leading to altered processing of anticipated rewards. The nucleus accumbens (NAcc) is particularly important for reward processes; task-based fMRI studies have found atypical activation of this region while the participants performed a reward task. Understanding how reward circuits are involved with ADHD may be further enhanced by considering how the NAcc interacts with other brain regions. Here we used the technique of resting-state functional connectivity MRI (rs-fcMRI) to examine the alterations in the NAcc interactions and how they relate to impulsive decision making in ADHD. Using rs-fcMRI, this study: examined differences in functional connectivity of the NAcc between children with ADHD and control children; correlated the functional connectivity of NAcc with impulsivity, as measured by a delay discounting task; and combined these two initial segments to identify the atypical NAcc connections that were associated with impulsive decision making in ADHD. We found that functional connectivity of NAcc was atypical in children with ADHD and the ADHD-related increased connectivity between NAcc and the prefrontal cortex was associated with greater impulsivity (steeper delayed-reward discounting). These findings are consistent with the hypothesis that atypical signaling of the NAcc to the prefrontal cortex in ADHD may lead to excessive approach and failure in estimating future consequences; thus, leading to impulsive behavior.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/metabolismo , Rede Nervosa/metabolismo , Núcleo Accumbens/metabolismo , Transdução de Sinais , Regulação para Cima , Transtorno do Deficit de Atenção com Hiperatividade/patologia , Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Criança , Comportamento Infantil , Tomada de Decisões , Feminino , Neuroimagem Funcional , Humanos , Comportamento Impulsivo/etiologia , Comportamento Impulsivo/psicologia , Imageamento por Ressonância Magnética , Masculino , Rede Nervosa/patologia , Vias Neurais , Núcleo Accumbens/patologia , Escalas de Graduação Psiquiátrica , Recompensa , Análise e Desempenho de Tarefas , Fatores de Tempo
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