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Research in the Anderson laboratory focuses on cellular signaling and ionic mechanisms that cause heart failure, arrhythmias and sudden cardiac death, major public health problems worldwide. Primary focus is on the multifunctional Ca2+ and calmodulin-dependent protein kinase II (CaMKII). The laboratory identified CaMKII as an important pro-arrhythmic and pro-cardiomyopathic signal, and its studies have provided proof of concept evidence motivating active efforts in biotech and the pharmaceutical industry to develop therapeutic CaMKII inhibitory drugs to treat heart failure and arrhythmias.
Under physiological conditions, CaMKII is important for excitation-contraction coupling and fight or flight increases in heart rate. However, myocardial CaMKII is excessively activated during disease conditions where it contributes to loss of intracellular Ca2+ homeostasis, membrane hyperexcitability, premature cell death, and hypertrophic and inflammatory transcription. These downstream targets a...ppear to contribute coordinately and decisively to heart failure and arrhythmias. Recently, researchers developed evidence that CaMKII also participates in asthma.
Efforts at the laboratory, funded by grants from the National Institutes of Health, are highly collaborative and involve undergraduate assistants, graduate students, postdoctoral fellows and faculty. Key areas of focus are:
• Ion channel biology and arrhythmias
• Cardiac pacemaker physiology and disease
• Molecular physiology of CaMKII
• Myocardial and mitochondrial metabolism
• CaMKII and reactive oxygen species in asthma
Mark Anderson, MD, is the William Osler Professor of Medicine, the director of the Department of Medicine in the Johns Hopkins University School of Medicine and physician-in-chief of The Johns Hopkins Hospital. view more
The Cardiology Bioengineering Laboratory, located in the Johns Hopkins Hospital, focuses on the applications of advanced imaging techniques for arrhythmia management. The primary limitation of current fluoroscopy-guided techniques for ablation of cardiac arrhythmia is the inability to visualize soft tissues and 3-dimensional anatomic relationships.
Implementation of alternative advanced modalities has the potential to improve complex ablation procedures by guiding catheter placement, visualizing abnormal scar tissue, reducing procedural time devoted to mapping, and eliminating patient and operator exposure to radiation.
Active projects include
• Physiological differences between isolated hearts in ventricular fibrillation and pulseless electrical activity
• Successful ablation sites in ischemic ventricular tachycardia in a porcine model and the correlation to magnetic resonance imaging (MRI)
• MRI-guided radiofrequency ablation of canine atrial fibrillation, and ...diagnosis and intervention for arrhythmias
• Physiological and metabolic effects of interruptions in chest compressions during cardiopulmonary resuscitation
Henry Halperin, MD, is co-director of the Johns Hopkins Imaging Institute of Excellence and a
professor of medicine, radiology and biomedical engineering. Menekhem M. Zviman, PhD is the laboratory manager.
The O’Rourke Lab uses an integrated approach to study the biophysics and physiology of cardiac cells in normal and diseased states.
Research in our lab has incorporated mitochondrial energetics, Ca2+ dynamics, and electrophysiology to provide tools for studying how defective function of one component of the cell can lead to catastrophic effects on whole cell and whole organ function. By understanding the links between Ca2+, electrical excitability and energy production, we hope to understand the cellular basis of cardiac arrhythmias, ischemia-reperfusion injury, and sudden death.
We use state-of-the-art techniques, including single-channel and whole-cell patch clamp, microfluorimetry, conventional and two-photon fluorescence imaging, and molecular biology to study the structure and function of single proteins to the intact muscle. Experimental results are compared with simulations of computational models in order to understand the findings in the context of the system as a whole....
Ongoing studies in our lab are focused on identifying the specific molecular targets modified by oxidative or ischemic stress and how they affect mitochondrial and whole heart function.
The motivation for all of the work is to understand
• how the molecular details of the heart cell work together to maintain function and
• how the synchronization of the parts can go wrong
Rational strategies can then be devised to correct dysfunction during the progression of disease through a comprehensive understanding of basic mechanisms.
Brian O’Rourke, PhD, is a professor in the Division of Cardiology and Vice Chair of Basic and Translational Research, Department of Medicine, at the Johns Hopkins University. view more
The Post Lab is involved in the Multi-Ethnic Study of Atherosclerosis (MESA), a collaborative study of the characteristics of subclinical cardiovascular disease (that is, disease detected non-invasively before it has produced clinical signs and symptoms) and the risk factors that predict progression to clinically overt cardiovascular disease or progression of the subclinical disease.
As MESA researchers, we study a diverse, population-based sample of 6,814 asymptomatic men and women aged 45-84. Approximately 38 percent of the recruited participants are white, 28 percent African-American, 22 percent Hispanic, and 12 percent Asian, predominantly of Chinese descent.
Participants were recruited from six field centers across the United States, including Johns Hopkins University. Each participant received an extensive physical exam to determine a number of conditions, including coronary calcification, ventricular mass and function, flow-mediated endothelial vasodilation, standard coron...ary risk factors, sociodemographic factors, lifestyle factors, and psychosocial factors.
Selected repetition of subclinical disease measures and risk factors at follow-up visits have allowed study of the progression of disease. Participants are being followed for identification and characterization of cardiovascular disease events, including acute myocardial infarction and other forms of coronary heart disease (CHD), stroke, and congestive heart failure; for cardiovascular disease interventions; and for mortality.
Wendy S. Post, MD, MS, is an associate faculty, Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, and a professor of medicine. view more
The Arking Lab
The Arking Lab studies the genomics of complex human disease, with the primary goal of identifying and characterizing genetics variants that modify risk for human disease. The group has pioneered the use of genome-wide association studies (GWAS), which allow for an unbiased screen of virtually all common genetic variants in the genome. The lab is currently developing improved GWAS methodology, as well as exploring the integration of additional genome level data (RNA expression, DNA methylation, protein expression) to improve the power to identify specific genetic influences of disease.
The Arking Lab is actively involved in researching:
• autism, a childhood neuropsychiatric disorder
• cardiovascular genomics, with a focus on electrophysiology and sudden cardiac death (SCD)
• electrophysiology is the study of the flow of ions in biological tissues
Dan E. Arking, PhD, is an associate professor at the McKusick-Nathans Institute of Genetic Medicine and Department of Medicine, D...ivision of Cardiology, Johns Hopkins University. view more
The Tomaselli lab is focused on the fundamental basis of excitability in the heart.
We study this problem at multiple levels of integration from molecules and cells to abnormalities of heart rhythm in patients.
At a molecular level, they seek to understand how ion channel proteins perform their essential tasks, in particular they are interested in a key paradox how these channels permit the flow of millions of ions a second, yet do this with exquisite selectivity (sodium channels allow sodium ions but not similarly sized and charged potassium ions).
More recently they have turned their attention to the regulation of sodium and potassium channels by important cellular signaling systems which are involved in not only in how the heart conducts electricity but also the force with which it contracts.
The diseased heart undergoes a series of changes, initially compensatory but ultimately maladaptive, that increase the risk of potentially lethal arrhythmias. These changes are comm...only referred to as remodeling. Dr. Tomaselli’s group is studying the remodeling process in animal models of heart failure using gene expression, protein and ionic current measurements. They have developed a canine microarray for the broad-based study of gene expression in the failing canine heart.
At the ultimate level of integration they are examining the role of implanted defibrillators (ICDs) in patients with diseased, remodeled hearts. They have initiated a study referred to as PROSe-ICD (PRospective Observational Study of the ICD in the prevention of sudden death).
PROSe-ICD has enrolled nearly 800 patients all have undergone detailed clinical and electrocardiographic studies as well as having blood collected for performing genetic and proteomic analyses. Over 25% of this cohort has undergone detailed cardiac imaging (MR and CT) and spectroscopy to identify imaging based markers of risk of sudden death. The overarching goal is to better understand the mechanisms of sudden arrhythmic death and to develop better predictors of risk of this devastating outcome.
Gordon F. Tomaselli, MD, is the chief of the Johns Hopkins Division of Cardiology and co-director of the Heart and Vascular Institute. view more
The Weiss Lab, which features a multi-disciplinary team at Johns Hopkins as well as at Cedars Sinai Medical Center in Los Angeles, is dedicated to identifying the most important clinical, genetic, structural, contractile and metabolic causes of sudden cardiac death as well as the means to reverse the underlying pathology and lower risk.
Current projects include research into energy metabolism in human heart failure and creatine kinase metabolism in animal models of heart failure.
Robert G. Weiss, MD, is professor of medicine, Radiology and Radiological Science, at the Johns Hopkins University.