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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 less
The Cardiac Bioelectric Systems Laboratory research focuses on both the physiological and pathophysiological function of cardiac cells at a multicellular, syncytial level. We use cell culture models in a manner akin to mathematical models in which elements of the model can be designed, synthesized or controlled. Our traditional approach consists of cultured, confluent monolayers of cardiac cells that number in the tens of thousands to a million. These cell monolayers can be engineered in terms of their tissue architecture, cell type, protein expression and microenvironment, and have been used to study clinically relevant phenomena in the heart that include electrical stimulation, electrical propagation, arrhythmia and cell therapy.
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