Ion channel kinetics and structure; Membrane Transport (Ion Transport); Molecular and Cellular Biology; Neurobiology; Pathophysiology; Gene Expression; Signal Transduction
Neuronal firing patterns are highly diverse because neurons regulate a wide variety of different behaviors and physiological functions including cognition and memory. Whether a neuron exhibits regular spiking, burst firing, adaptation or high frequency firing will largely be determined by which specific ion channel genes a neuron chooses to express. I am interested in a class of potassium channels that are sensitive to intracellular sodium. There are two members in this family, known as Slack and Slick, and both channel subunits are expressed in many different types of neurons. I am particularly interested in how these channels contribute to the firing patterns of pain-sensing neurons and neurons of the cerebral cortex. Understanding when, where and how these channels are working should provide important information on sensory and cortical processing and will provide insights on nociception, psychiatric disorders such as schizophrenia and bipolar disorder and neurological diseases such as epilepsy.
Endocrinology, Diabetes and Metabolism; Neurodegenerative disorders; Pathophysiology; Endocrinology; Molecular Basis of Disease
Dr. Browne’s research is focused primarily on the clinical biochemistry of oxidative stress (OS) in human health and disease. Specifically, his research focuses on mechanisms of oxidative lipid damage and the antioxidant roles of high-density lipoproteins (HDL. This research includes pure biomarker method development and validation employing primarily high pressure liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) along with collaborative clinical studies of the role of oxidative stress in cancer, infertility and women’s health, and neurological disease. Current studies on-going in Dr. Browne’s laboratory include investigations of the role of HDL and PON1 in embryo morphology outcomes during in vitro fertilization (IVF), a study of the role of oxysterols in Multiple Sclerosis disease progression and investigations of the role of bioactive lipid mediators in response to air pollution.
Neurology; Neurodegenerative disorders; Pathophysiology; Apoptosis and cell death; Cytoskeleton and cell motility; Molecular and Cellular Biology; Molecular genetics; Neurobiology; Protein Folding; Gene Expression; Transcription and Translation; Signal Transduction; Toxicology and Xenobiotics
My research is aimed at finding the cause and a cure for Parkinson’s disease. Parkinson’s disease (PD) is defined by a characteristic set of locomotor symptoms (rest tremor, rigidity, bradykinesia and postural instability) that are believed to be caused by the selective loss of dopaminergic (DA) neurons in substantia nigra. The persistent difficulties in using animals to model this human disease suggest that human nigral dopaminergic neurons have certain vulnerabilities that are unique to our species. One of our unique features is the large size of the human brain (1350 grams on average) relative to the body. A single nigral dopaminergic neuron in a rat brain (2 grams) has a massive axon arbor with a total length of 45 centimeters. Assuming that all mammalian species share a similar brain wiring plan, we can estimate (using the cube root of brain weight) that a single human nigral dopaminergic neuron may have an axon with gigantic arborization that totals 4 meters. Another unique feature of our species is our strictly bipedal movement, which is affected by Parkinson’s disease, in contrast to the quadrupedal movement of almost all other mammalian species. The much more unstable bipedal movement may require more dopamine, which supports the neural computation necessary for movement. The landmark discovery of human induced pluripotent stem cells (iPSC) made it possible to generate patient-specific human midbrain dopaminergic neurons to study Parkinson’s disease. A key problem for dopaminergic neurons is the duality of dopamine as a signal required for neural computation and a toxin as its oxidation produces free radicals. Our study using iPSC-derived midbrain dopaminergic neurons from PD patients with parkin mutations and normal subjects shows that parkin sustains this necessary duality by maintaining the precision of the signal while suppressing the toxicity. Mutations of parkin cause increased spontaneous release of dopamine and reduced dopamine uptake, thereby disrupting the precision of dopaminergic transmission. On the other hand, transcription of monoamine oxidase is greatly increased when parkin is mutated. This markedly increases dopamine oxidation and oxidative stress. These phenomena have not been seen in parkin knockout mice, suggesting the usefulness of parkin-deficient iPSC-derived midbrain DA neurons as a cellular model for Parkinson’s disease. Currently, we are using iPS cells and induced DA neurons to expand our studies on parkin to idiopathic Parkinson’s disease. We are also utilizing the molecular targets identified in our studies to find small-molecule compounds that can mimic the beneficial functions of parkin. The availability of human midbrain DA neurons should significantly speed up the discovery of a cure for Parkinson’s disease.
Cardiovascular Disease; Internal Medicine; Nephrology; Pathophysiology; Vascular and Interventional Radiology; Cardiac pharmacology
(1) Role of the sympathoadrenal system in hypertension, postural adaptation, and long-term cardiovascular adaptation (2) Control of regional and systemic blood flow during acute stress responses (3) Mechanisms of stress responses and vasoreactivity, both in vivo and in vitro, including metabolic interactions (4) Cardiovascular drug effects (5) Outcomes of drug therapies
Ophthalmology; Retina; Pediatric Ophthalmology; Pathophysiology; Vision science
Dr. Reynolds has various research interests in pediatric ophthalmology, but his main niche is retinopathy of prematurity. ROP is a disease of the developing immature retinal vasculature, modulated by hyperoxia/hypoxia micro environments in the retina, which can lead to neovascularization, scarring, and potential blindness. Dr. Reynolds is a recognized expert in the field and is the author of many peer reviewed articles and several invited review chapters. His NIH funding has been nearly continuous while at U.B. while participating in several multi-center clinical trials in ROP as center P.I. and project director. Dr. Reynolds was the center P.I. at U.B. for the first large treatment trial for ROP, CRYO-ROP. This trial established the first known effective treatment for this high socioeconomic impact disease. As center P.I. he participated in the group collaborative publications as well as co authoring many individually by-lined papers (Ref. 22, 23, 24, 25, 26, 28, 29, 31, 32, 37, 40, 42). His successful and productive work as a center P.I. on this trial led to the funding for the LIGHT-ROP multi-center trial for which he served as project director and lead P.I. This trial definitively answered a long debated hypothesis in ROP i.e. that ambient light was not a causal factor in ROP (Ref. 38, 41, 45, 47). Dr. Reynolds was again selected as a center P.I. for the next large multi-center ROP trial, ET-ROP, which just reported its primary results demonstrating that earlier laser treatment for this disease was effective. Although all multi-center clinical trials are cooperative agreements at the NIH and thus are funded as UO1s rather than RO1s, Dr. Reynolds was an integral participant in all the ROP trials from the mid-eighties to the present, leading one, and actively co-authoring many of the studies?publications as noted in the bibliography. The future of Dr. Reynolds?ROP research will undoubtedly involve more funded multi-center trials. However, a basic science collaboration into the pathophysiology of ROP in an animal model is planned, investigating the renin-angiotension connection.
Retina; Gene therapy; Neurodegenerative disorders; Pathophysiology; Protein Folding; Gene Expression; Signal Transduction
I am a Clinician Scientist working in the field of hereditary retinal and macular degenerations. I direct a regional referral service for these diseases at the Ross Eye Institute. My NIH- and VA-funded laboratory is focused on the development of gene-based therapeutics for hereditary retinal degenerations and common age-related macular degeneration.
Neurodegenerative disorders; Pathophysiology; Cytoskeleton and cell motility; Molecular Basis of Disease; Molecular and Cellular Biology; Neurobiology; Neuropharmacology; Signal Transduction
Synaptic Mechanisms of Mental Health and Disorders Our research goal is to understand the synaptic action of various neuromodulators that are linked to mental health and illness, including dopamine, stress hormones, and disease susceptibility genes. Specifically, we try to understand how these neuromodulators regulate glutamatergic and GABAergic transmission in prefrontal cortex (PFC), which is important for emotional and cognitive control under normal conditions. We also try to understand how the aberrant action of neuromodulators under pathological conditions leads to dysregulation of synaptic transmission in PFC, which is commonly implicated in brain disorders. The major techniques used in our studies include: • whole-cell patch-clamp recordings of synaptic currents, • viral-based in vivo gene transfer, • biochemical and immunocytochemical detection of synaptic proteins, • molecular analysis of genetic and epigenetic alterations, • chemogenetic manipulation of neuronal circuits, • behavioral assays. By integrating the multidisciplinary approaches, we have been investigating the unique and convergent actions of neuromodulators on postsynaptic glutamate and GABAA receptors, and their contributions to the pathogenesis of a variety of mental disorders, including ADHD, autism, schizophrenia, depression, PTSD and Alzheimer‘s disease.