Cape Saint Claire, MD, United States
Cape Saint Claire, MD, United States

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Bassett D.S.,University of Pennsylvania | Yang M.,University of Pennsylvania | Wymbs N.F.,University of California at Santa Barbara | Wymbs N.F.,Johns Hopkins Medical Institution | Grafton S.T.,University of California at Santa Barbara
Nature Neuroscience | Year: 2015

Distributed networks of brain areas interact with one another in a time-varying fashion to enable complex cognitive and sensorimotor functions. Here we used new network-analysis algorithms to test the recruitment and integration of large-scale functional neural circuitry during learning. Using functional magnetic resonance imaging data acquired from healthy human participants, we investigated changes in the architecture of functional connectivity patterns that promote learning from initial training through mastery of a simple motor skill. Our results show that learning induces an autonomy of sensorimotor systems and that the release of cognitive control hubs in frontal and cingulate cortices predicts individual differences in the rate of learning on other days of practice. Our general statistical approach is applicable across other cognitive domains and provides a key to understanding time-resolved interactions between distributed neural circuits that enable task performance. © 2015 Nature America, Inc. All rights reserved.


Mourkioti F.,Stanford University | Kustan J.,Stanford University | Kraft P.,Stanford University | Day J.W.,Stanford University | And 7 more authors.
Nature Cell Biology | Year: 2013

Duchenne muscular dystrophy (DMD), the most common inherited muscular dystrophy of childhood, leads to death due to cardiorespiratory failure. Paradoxically, mdx mice with the same genetic deficiency of dystrophin exhibit minimal cardiac dysfunction, impeding the development of therapies. We postulated that the difference between mdx and DMD might result from differences in telomere lengths in mice and humans. We show here that, like DMD patients, mice that lack dystrophin and have shortened telomeres (mdx/mTR KO) develop severe functional cardiac deficits including ventricular dilation, contractile and conductance dysfunction, and accelerated mortality. These cardiac defects are accompanied by telomere erosion, mitochondrial fragmentation and increased oxidative stress. Treatment with antioxidants significantly retards the onset of cardiac dysfunction and death of mdx/mTR KO mice. In corroboration, all four of the DMD patients analysed had 45% shorter telomeres in their cardiomyocytes relative to age- and sex-matched controls. We propose that the demands of contraction in the absence of dystrophin coupled with increased oxidative stress conspire to accelerate telomere erosion culminating in cardiac failure and death. These findings provide strong support for a link between telomere length and dystrophin deficiency in the etiology of dilated cardiomyopathy in DMD and suggest preventive interventions. © 2013 Macmillan Publishers Limited. All rights reserved.


Qiu T.,Johns Hopkins Medical Institution | Wu X.,Johns Hopkins Medical Institution | Wu X.,Shihezi University | Zhang F.,Shihezi University | And 3 more authors.
Nature Cell Biology | Year: 2010

Parathyroid hormone (PTH) regulates calcium homeostasis and bone metabolism by activating PTH type I receptor (PTH1R). Here we show that transforming growth factor (TGF)-Β type II receptor (TΒRII) forms an endocytic complex with PTH1R in response to PTH and regulates signalling by PTH and TGF-Β. TΒRII directly phosphorylates the PTH1R cytoplasmic domain, which modulates PTH-induced endocytosis of the PTH1R-TΒRII complex. Deletion of TΒRII in osteoblasts increases the cell-surface expression of PTH1R and augments PTH signalling. Conditional knockout of TΒRII in osteoblasts in mice results in a high bone mass with increased trabecular bone and decreased cortical bone, similar to the bone phenotype in mice expressing a constitutively active PTH1R. Disruption of PTH signalling by injection of PTH(7-34) or ablation of PTH1R rescues the bone phenotype of TΒRII knockout mice. These studies reveal a previously unrecognized function for TΒRII and a mechanism for integration of PTH and local growth factor at the membrane receptor level. © 2010 Macmillan Publishers Limited. All rights reserved.


Hoyer E.H.,Johns Hopkins Hospital | Celnik P.A.,Johns Hopkins Hospital | Celnik P.A.,Johns Hopkins Medical Institution
Restorative Neurology and Neuroscience | Year: 2011

Stroke is the leading cause of long-term disability. Understanding how people recover from stroke and other brain lesions remain one of the biggest conundrums in neuroscience. As a result, concerted efforts in recent years have focused on investigating the neurophysiological changes that occur in the brain after stroke, and in developing novel strategies to enhance motor recovery. In particular, transcranial magnetic stimulation (TMS) is a non-invasive tool that has been used to investigate the brain plasticity changes resulting from stroke and as a therapeutic modality to safely improve motor function. In this review, we discuss the contributions of TMS to understand how different motor areas, such as the ipsilesional hemisphere, secondary motor areas, and contralesional hemisphere are involved in motor recovery. We also consider recent studies using repetitive TMS (rTMS) in stroke patients to enhance upper extremity function. Although further studies are needed, these investigations provide an important starting point to understand the stimulation parameters and patient characteristics that may influence the optimal response to non-invasive brain stimulation. Future directions of rTMS are discussed in the context of post-stroke motor recovery. © 2011 - IOS Press and the authors. All rights reserved.


Malayeri A.A.,Johns Hopkins Medical Institution
Journal of computer assisted tomography | Year: 2013

Adrenal masses are among the most common incidentally discovered lesions on cross-sectional imaging with estimated incidence of approximately 5%. In addition, adrenal lesions can also be detected as part of an endocrinology workup with suspicion of a functional adrenal mass. Regardless of the source of detection, it is crucial to differentiate a benign from a malignant process and furthermore utilize characteristic imaging appearance of different adrenal masses to facilitate diagnosis and guide management. There are numerous imaging protocols and postprocessing methods for evaluation of adrenal masses with high sensitivity and specificity with small differences between institutions. Currently, the most widely used imaging modality for evaluation of adrenal mass is computed tomography without and with contrast washout assessment. In this article, we review diagnostic approaches to adrenal masses using computed tomography and magnetic resonance imaging techniques and present imaging strategies utilized at our institution. The advantages and challenges of these imaging modalities for evaluation of adrenal pathologies are discussed.


Yousem D.M.,Johns Hopkins Medical Institution
Neuroimaging Clinics of North America | Year: 2012

Radiology benefits managers (RBMs) and computerized decision support offer different advantages and disadvantages in the efforts to provide appropriate use of radiology resources. RBMs are effective in their hard-stop ability to reject inappropriate studies, incur a significant cost, and interpose an intermediary between patient and physician. Decision support is a more friendly educational product, but has not been implemented for all clinical indications and its efficacy is still being studied. © 2012 Elsevier Inc.


Junkins-Hopkins J.M.,Johns Hopkins Medical Institution
Journal of the American Academy of Dermatology | Year: 2010

Dialogues in Dermatology, a monthly audio program from the American Academy of Dermatology, contains discussions between dermatologists on timely topics. Commentaries from Dialogues Editor-in-Chief Jacqueline M. Junkins-Hopkins, MD, are provided after each discussion as a topic summary and are provided here as a special service to readers of the Journal of the American Academy of Dermatology. © 2009 by the American Academy of Dermatology, Inc.


Tamma P.D.,Johns Hopkins Medical Institution | Aucott S.W.,Johns Hopkins Medical Institution | Milstone A.M.,Johns Hopkins Medical Institution
Infection Control and Hospital Epidemiology | Year: 2010

Infection prevention guidelines do not endorse chlorhexidine gluconate (CHG) use in neonates who are less than 2 months old. A survey of US neonatology program directors revealed that most neonatal intensive care units use CHG, often with some restrictions. Prospective studies are needed to further address concerns regarding the safety of CHG in patients in the neonatal intensive care unit. © 2010 by The Society for Healthcare Epidemiology of America. All rights reserved.


Junkins-Hopkins J.M.,Johns Hopkins Medical Institution
Journal of the American Academy of Dermatology | Year: 2011

Dialogues in Dermatology, a monthly audio program from the American Academy of Dermatology, contains discussions between dermatologists on timely topics. Commentaries from Dialogues Editor-in-Chief Jacqueline M. Junkins-Hopkins, MD, are provided after each discussion as a topic summary and are provided here as a special service to readers of the Journal of the American Academy of Dermatology. © 2009 by the American Academy of Dermatology, Inc.


Zulfiqar M.,Johns Hopkins Medical Institution | Yousem D.M.,Johns Hopkins Medical Institution | Lai H.,Johns Hopkins Medical Institution
American Journal of Roentgenology | Year: 2013

OBJECTIVE. The purpose of this article is to determine via meta-analysis whether apparent diffusion coefficient (ADC) predicts astrocytoma prognosis independent of grade. MATERIALS AND METHODS. Survival data were subjected to Mantel Haenszel analysis in four qualifying studies. Stratification by tumor grade was also performed. RESULTS. The survival rates of malignant astrocytomas, grade 3 and 4 (p, 0.004 and < 0.0001, respectively) were worse below a specific ADC value, independent of grade. CONCLUSION. Low ADC values correlate with poor survival in malignant astrocytomas independent of tumor grade. © American Roentgen Ray Socoety.

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