Basic Science



Timothy Angelotti, MD, PhD

Cultured mouse sympathetic ganglion neuron stained with an antibody to MAP2, a cytoskeleton protein. (Photo courtesy of Dr. Carl Hurt)

My research efforts are focused on investigating the pharmacological and physiological interface of the autonomic nervous system with effector organs.  Utilizing molecular, cellular, and electrophysiological techniques, I am examining the function of a2 adrenergic receptors in sympathetic neurons cultured alone, or in the presence of other neurons, cardiac myocytes, or smooth muscle cells.  Sympathetic neurons are isolated from various transgenic knock-out and knock-in mice, which have been designed to express altered adrenergic receptor subtypes (e.g. a2A/C, b1, b2).  Using recombinant adenovirus constructs encoding additional wild-type, mutant, or chimeric adrenergic receptors, I am able to further modify the pharmacology and physiology of this system.  Receptor binding, immunocytochemistry, single-cell analysis of neurotransmitter release, and standard molecular biology are the techniques that are employed to characterize this dynamic system.  Development of this in vitro model of the sympathetic nervous system will allow us to better understand its role in sympathetically-mediated pain and in the stress response to surgery and critical illness.

E-mail Dr. Angelotti


Martin Angst, MD

The clinical pharmacology of analgesic drugs represents the field of our research. We focus on two major areas: (1) opioid pharmacology and (2) algorithms for the rational development of new analgesic compounds. We address our questions by conducting experimental pain studies in human volunteers as well as clinical studies in patients suffering from acute and chronic pain.

Our tool: The experimental pain laboratory

A major tool for pursuing our research is the human experimental pain laboratory. Unlike clinical pain, experimental pain can be studied under well-controlled and standardized conditions that are minimally affected by confounding factors. Models with implicit neurophysiological meaning allow answering questions from a mechanistic rather than a phenomenological perspective. Over the years we have adapted a series of experimental pain models.

  1. Models of acute nociceptive pain (heat and electrical stimuli) are useful tools to derive accurate pharmacodynamic parameters (time to peak effect, duration of action, spread of analgesic action).
  2. Models of inflammatory pain (freeze lesion and UV-B lesion) are useful to predict analgesic and anti-hyperalgesic drug action for clinical pain associated with inflammation.
  3. Models of centrally (CNS) enhanced pain (intradermal electrical stimulation) are useful for studying drug effects on mechanisms underling chronic pain in humans.

More recently, microdialysis has been added to our laboratory allowing the in-vivo sampling of inflammatory and nociceptive biomarkers from various tissue sites.

Research focus 1: Opioid pharmacology - Neuropharmacological plasticity

While initial studies focused on characterizing common pharmacodynamic parameters after systemic, intrathecal or epidural administration of opioids, our current research has moved into the field of neuropharmacological plasticity. This field characterizes drug-induced changes in neuronal signaling. A current hot topic regarding opioids is the phenomenon of opioid-associated hyperalgesia. Evidence is accumulating that administration of opioids for alleviating pain may induce a state of pain hypersensitivity. In other words, patients receiving opioids for pain control may hurt more because opioids have been administered. Our research needs to clarify the conditions under which opioid-associated hyperalgesia occurs, the clinical importance of opioid-associated hyperalgesia, and ways to prevent it.

Research focus 2: Analgesic drug development - Early phase I/II trials

Human experimental pain studies are a logical intermediate component of an analgesic drug development plan. Data derived from animal studies have limited validity for predicting the clinical utility of a novel analgesic compound. Human experimental pain studies are expediently conducted in a small number of subjects and facilitate the decision whether a novel analgesic compound warrants further development in expensive, large-scale clinical trials.

Experimental pain studies in humans also offer an opportunity to collect additional relevant data, i.e. pharmacokinetic data via high resolution plasma sampling techniques or data relating to biomarkers via microdialysis sampling techniques.

E-mail Dr. Angst   |   http//myprofile.cos.com/angst


David Clark, MD, PhD

Current projects being pursued in the Clark lab can generally be placed in one of to categories. One group of projects involves the investigation of the roles of heme oxygenase in nociceptive mechanisms. To this point we have demonstrated a role for this enzyme in many rodent pain models including models of inflammatory, incisional and neuropathic pain. We are currently addressing issues related to specific spinal neurotransmitter systems which may be modulated by heme oxygenase, examining the role of heme oxygenase in modifying analgesic responses to opioids, and determining the extent and nature of the interactions between heme oxygenase and nitric oxide.

The second group of projects involves the mechanistic exploration of opioid-induced hyperalgesia. Experiments from our lab have to this point demonstrated thermal hyperalgesia and mechanical allodynia in mice and rats after the cessation of opioid administration. This hyperalgesia has been partially characterized pharmacologically. Ongoing studies seek to further elucidate the mechanism of this form of hyperalgesia as well as test methods for preventing or limiting its manifestation. We are currently using behavioral, immunohistochemical and biochemical methods.

E-mail Dr. Clark


David Drover, MD

My research interest is in clinical research on the pharmacokinetics and pharmacodynamics of drugs. Medications studied are those commonly used for anesthesia and analgesia. Additionally, other drugs are studied if they have unique characteristics that require intensive or specialized monitoring. Particular effort is used to obtain quality real-time data from intensive pharmacokinetic - pharmacodynamic studies to enable mathematical modeling of drug effect on the human body. Mathematical modeling of data is mainly performed with NONMEM. Where possible, research projects use the electroencephalogram to quantitate pharmacodynamic effect and develop mathematical models to relate pharmacokinetics to pharmacodynamic response. The main interest of my research projects is to develop novel ways to model and describe clinical pharmacology relationships.

E-mail Dr. Drover


Rona Giffard, MD, PhD

The cellular and molecular basis for brain cell vulnerability to ischemic injury is our focus. Astrocytes and neurons in brain interact, and have unique vulnerabilities to injury based on their patterns of gene expression. Injury of individual cell types, gene therapy of injury, and interaction between cell types during injury is studied.

E-mail Dr. Giffard   |   http://med.stanford.edu/anesthesia/giffardlab/


Richard Jaffe, MD, PhD

My laboratory research interests are focused in two areas (1) the physiological and pharmacological basis of differential nerve block, and (2) the use of electrophysiological techniques to detect and manage intraoperative cerebral ischemia.

Some local anesthetics, opiates and calcium channel blockers are known to block nerve conduction in specific nerve fibers (e.g. sensory axons) while having less effect on other fiber types (e.g. motor axons). Using single-fiber recording and perfusion techniques I am able to study action potential generation and propagation in both central and peripheral axons. The goal of this research is to understand the mechanisms by which differential nerve block can be produced, and to use this information to develop novel clinical techniques for regional analgesia.

The early detection and prompt treatment of focal cerebral ischemia is essential to minimize intraoperative damage to the central nervous system. The goal of this research (in collaboration with Jaime Lopez, M.D., Department of Neurology) is to develop and characterize sensitive electrophysiologic techniques using evoked potentials and electroencephalography to detect cerebral ischemia. Using a standardized rat model of focal cerebral ischemia we are able to evaluate various detection and treatment modalities.

E-mail Dr. Jaffe


Bruce MacIver, MSc, PhD

The long-term goal of our research is to provide physiological background information required for the rational design of safer and more effective anesthetics and analgesics.

Hippocampal Research

We investigate the cellular, synaptic and molecular mechanisms of action of central nervous system drugs; especially barbiturates, opiates, anesthetics and other CNS depressants. Electrophysiological recording techniques and selective pharmacological probes are used to investigate the sites and mechanisms of action for CNS depressants. Most of our studies focus on the CA 1 area in rat hippocampal brain slices. Neurons in this brain area are depressed by anesthetics through a combination of pre- and postsynaptic actions on glutamate and GABA mediated neurotransmission.

Theta Research

The effects of pharmacological agents on EEG waves generated by the neocortex are also being examined. EEG theta activity (4 to 12 Hz) is one of many rhythms, like alpha and delta (slow wave sleep) rhythms that are altered by anesthetics. Patch clamp and electrophysiological recording techniques are used to look at the effects of anesthetics on carbachol and bicuculline induced theta activity in neocortical brain slices. Anesthetic effects on brain slice micro-EEG activity are correlated to EEG effects seen in animals and humans during anesthesia. Effects on micro-EEG theta activity were shown to involve actions at GABA and glutamate synapses.

Theta activity can be recorded from specific regions (green dots) of cortex in rat brain slices. Comparison of micro-EEG signals and intracellular recordings (whole cell) reveal that the low frequency theta waves (~ 8 Hz) were generated by synchronous synaptic potentials and discharge activity of cortical neurons. The discharge of each cortical neuron appears to contribute ~ 1.0 µV to the micro-EEG signal, so theta activity requires synchronous activity in ~ 100 neurons in each cortical location. Theta activity is known to be important for spacial mapping and may provide a 'binding' mechanism that contributes to the formation of memory in general. When selective populations of neurons are synchronously active they can interact in a Hebbian manner to change the strength of synaptic inputs that are timed at the theta frequency. Theta activity is also known to be particularly sensitive to anesthetic agents at concentrations which block memory formation. Preliminary studies in our laboratory indicate that brain slice theta activity is also depressed by anesthetics and that this depression occurs with a profile similar to in vivo responses.

E-mail Dr. MacIver   |   http://www.stanford.edu/group/maciverlab/


Sean Mackey, MD, PhD

Pain is the primary complaint resulting in physician visits and health care resource utilization. The importance of pain as a major worldwide health care problem has been recognized by the World Health Organization, and the need for further research into its mechanisms and control was recognized by the U.S. Congress in its declaration of the years 2001-2010 as the Decade of Pain Control and Research.
The presence of pain and its inadequate treatment in a variety of clinical settings has significant societal impact.  Pain contributes to the overall economic burden of disease through increased direct medical costs caused by additional health care resource utilization.  It has been estimated that in the United States the cost of health care, compensation, and litigation resulting from pain is more than $200 billion annually.
Historically, pain has been considered in relation to its etiologic or disease factors, such as the relationship between surgery and postoperative pain, herpes zoster and postherpetic neuralgia, and arthritis and painful joints.  This has had the effect of addressing pain as a symptom of disease, and although much progress has been made in understanding the molecular and cellular mechanisms of disease, the resulting pain has not necessarily been alleviated.  What is required, and has been missing from the evaluation, is an understanding of the underlying mechanisms responsible for the pain itself.
Dr. Mackey has focused his efforts on elucidating and characterizing these underlying mechanisms of pain.  In particular, he has focused his efforts on characterizing the mechanisms of pain from the level of the network to behavior (see figure).  He uses a systems neuroscience approach which includes the integration of advanced neurobehavioral, psychophysical and neuroimaging techniques.



Learned control of ACC activity and pain. A) Change in fMRI activity B) Control over BOLD activity increased significantly through training. C) Control over pain increased significantly throuhg training. *p<0.05, linear regression. Some current research projects and themes:

1. Real-Time Brain Control for Pain
Attaining control over specific neural processes is the primary goal of neuropharmacology and neurostimulation; it is also a critical objective of biological psychiatry and psychology. Training people to be able to modulate specific neural processes has the potential to enable them to have greater control over the resulting behavior, cognition, or associated disease. Recently we have demonstrated that patients with chronic pain can learn to control a specific region of their brain – the rostral anterior cingulate cortex (rACC) – that is associated with pain processing and perception (PNAS, December 2005, 102:51; 18626-31). Importantly, we found in that study that the increased control in localized brain activity was associated with improvement in pain control. We are expanding this work to: (1) investigate learned control of specific brain networks, (2) determine the optimal brain regions for learned control, (3) characterize the long term effects of this unique methodology and (4) apply it to other neuroscience fields such as depression, addiction and cognitive development. This exciting and unique multidisciplinary collaboration brings together expertise from the fields of Pain, Radiology, Psychology, and Electrical Engineering.  Stanford is currently the only institution in the world where this work is occurring.
2. Neuroimaging of the human spinal cord, brainstem and brain and characterization of reward systems, affective dimensions of pain and neural plasticity of pay
3. Personalized Pain Medicine
The last decade has seen a significant increase in the number and type of pharmacologic therapies for the treatment of chronic pain. Frustratingly, each medication produces pain relief for only a minority (typically 30%) of patients.  Not surprisingly, few physicians have the patience required to persist in a strategy involving months of frustrating side-effect laden medication trials until the correct one is found. What we need is a method to identify which individual patient with a particular chronic pain problem will respond to a specific drug. We have put together a multidisciplinary team of researchers and clinicians  to achieve this goal.  We have been developing and using techniques such as: (1) pharmacologic fMRI to elucidate central neural correlates of drug response and side effects, (2) sophisticated pharmacokinetic/pharmacodynamic drug models to characterize individual drug concentrations and effects, (4) novel neurobehavioral and psychophysical measurements to precisely characterize the perceptual aspects of the pain experience, (5) genomics to characterize candidate gene polymorphisms responsible for individual differences in pain perception and analgesic efficacy and (6) novel epidemiologic and statistical methods to develop multivariate models which ultimately predict individual drug responsiveness.

For further information see: Systems Neuroscience and Pain Lab and Paincenter Web Site

E-mail Dr. Mackey


Andrew Patterson, MD, PhD

My research focuses on cardiovascular physiology. I am interested in the roles of adrenergic receptors in both normal and diseased hearts. I am also interested in developing gene therapy techniques that might be used to treat heart failure. In addition, my laboratory group has collaborated on several projects designed to elucidate the mechanisms of vasoregulation. The techniques employed in my laboratory range from microsurgery to gene therapy to ECG telemetry to exercise treadmill testing using mice.

E-mail Dr. Patterson


Ronald Pearl, MD, PhD

My research examines mechanisms and therapy of experimental pulmonary hypertension. We use the combination of pneumonectomy and monocrotaline administration to produce proliferative pulmonary hypertension in rats. We are currently examining the changes at a transcriptional and cellular level which result in pulmonary hypertension and the ability of vasodilator, immunosuppresive, and antiproliferative therapies to prevent and/or reverse the pulmonary hypertension. Ongoing research will develop a model of pulmonary hypertension in genetically altered mice and the ability of gene therapy to cure pulmonary hypertension.

E-mail Dr. Pearl


James Trudell, PhD

My research interests include usage of computational chemistry to develop molecular theories of anesthesia. I collaborate with three groups that use molecular biology to make site-directed mutations in ligand-gated ion channels. Molecular modeling of these channels is used to visualize the effect of mutations and to predict new mutations that will further refine their structure. I also use quantum mechanics calculations to determine the kinds of interactions that are likely to provide binding energy for anesthetic molecules at their sites of action.

ANESTHETIC INTERACTION WITH MEMBRANE PROTEINS
JIM TRUDELL, PH.D., EDWARD J. BERTACCINI, MD

At the turn of the last century the Meyer-Overton relationship was proposed that relates anesthetic potency to the fat solubility of the anesthetic.  This relationship fueled a large academic effort to find the mechanism of anesthetic action. Not surprisingly much attention was focused on determining whether the site of anesthetic action was the lipid layer of the plasma membrane where anesthetics would in some way perturb the lipid bilayer structure. While the results did explain some of the characteristics of anesthetic  action there were also many deficiencies. The attention then shifted to the lipid-protein interface where it was thought that anesthetics may disturb the lipid microenvironment around the protein and thereby change the function of the protein. Recently most research has centered on anesthetics directly interacting with membrane proteins and thereby causing a change in their function. Unfortunately anesthetics do not have a high enough affinity for proteins to study the interaction using classical biochemical means. So if the anesthetics were going to play tough and be elusive, the researchers have to be equally inventive. Bring in the big guns: computational chemistry to develop molecular theories of anesthesia.

Drs. Jim Trudell and Ed Bertaccini have been using the methods of bioinformatics, structural biology and computational chemistry to build 3 dimensional models of the various multi-subunit ligand-gated ion channels through which anesthetics are thought to mediate their effects. Much of their work has been focused on the glycine and GABAA receptors found in the brain and spinal cord because they have been shown to play a role in anesthetic action.  By doing this extensive modeling study they have developed the first three dimensional visualization of an anesthetic binding site within a clinically relevant protein.  Using computational chemistry techniques, they have mapped out this binding site so as to determine the chemical requirements for anesthetic binding. They collaborate with three groups that use molecular biology to make site-directed mutations in these ion channels. The original models are then tweaked to include the modification of the protein sequence and the binding pocket is reexamined. Molecular modeling of these channels is used to visualize the effects of mutations, to predict new mutations to be made and test their properties. This new information will be used to further refine the 3-D structure of the protein.

The results of this work are best seen by looking at the computer images of the receptor model with and without anesthetics. They found a binding pocket in the midst of the protein where there is room for the anesthetic to sit. It seems the anesthetic is held there by weak forces exerted by lipophilic and hydrophilic amino acid residues. If the amino acids within that pocket were modified to make them bigger they could either mimic or block the action of an anesthetic. Even more intriguing-, if the subunits of the receptor are allowed to move in the model, the effect of the anesthetic on the ion channel pore may become apparent.

So will we be better off knowing how inhalational anesthetics work?  The answer to that may be yes as knowing how anesthetics work may make it possible to design better anesthetics- ones with more selective and specific actions and ones that might also be more readily reversible.

E-mail Dr. Trudell


David Yeomans, PhD

This is a picture of primate dorsal root ganglia neurons demonstrating expression of the opiate analgesic peptide leu-enkephalin after application of a recombinant herpes virus encoding the gene for human preproenkephalin to the skin.

We are leading the way with two potentially revolutionary approaches to the treatment of chronic pain, namely transplantation and gene therapy. In the first approach, cells taken from the adrenal gland are transplanted on top of the spinal cord through a spinal needle. These cells make and secrete numerous natural analgesic substances, acting like a pump to produce a constant inhibition of pain. Unlike a pump however, these cells are alive, meaning that they keep making and secreting the analgesic chemicals for months.

The primary problems in gene therapy have been the targeting of the right cells, and the duration of the desired effect. We have used a highly modified herpes simplex virus (the kind that causes cold sores) to carry analgesic genes into the pain sensing cells. Because herpes viruses stay in these cells for the life of the host naturally, we should obtain very long lasting analgesic effects using these treatments. Thus, we are making use of the natural proclivity of herpes for entering and staying in the very cells we are interested in. In this way, we target pain treatment to painful areas, and only painful areas. These new approaches to therapy could revolutionize the treatment of chronic pain.

E-mail Dr. Yeomans


Ronald Pearl, MD, PhD

My research examines mechanisms and therapy of experimental pulmonary hypertension. We use the combination of pneumonectomy and monocrotaline administration to produce proliferative pulmonary hypertension in rats. We are currently examining the changes at a transcriptional and cellular level which result in pulmonary hypertension and the ability of vasodilator, immunosuppresive, and antiproliferative therapies to prevent and/or reverse the pulmonary hypertension. Ongoing research will develop a model of pulmonary hypertension in genetically altered mice and the ability of gene therapy to cure pulmonary hypertension.

E-mail Dr. Pearl


Obstetric Anesthesia Research Group

The obstetric anesthesia research group addresses a wide variety of questions related to the field. Two areas are currently our major focus:

  • The use of spinal opioids for epidural and spinal anesthesia and analgesia.
  • Spinal anesthesia for cesarean delivery.

In addition, we have done research on the economics of obstetric anesthesia, patient perception of risk, experimental pain, and the use of nitroglycerin for preterm labor and external cephalic version.

We have a large number of faculty involved in research and generally have 1 or 2 post-doctoral fellows conducting clinical studies. We have successfully helped undergraduate students, medical students, and residents complete research projects. Our fellows come from our own residency program as well as other academic institutions, and we have provided research opportunities for several foreign scholars. Our past fellows have gone on to academic careers or been very successful in private practice.

One of the strengths of our group is our ability to collaborate with a variety of people in the institution. We have conducted projects in the past with Drs. Alex Macario (economics), Yasser El Sayed (Fetal-Maternal Medicine), David Drover (pharmacokinetics and statistics), and Martin Angst (experiment pain). In the future we hope to collaborate with Dr. David Yeoman's experimental pain laboratory. Regular interaction among the members of the group is the key to the success of our active group. This is facilitated by monthly research meetings and journal clubs. We have also developed a formalized mentoring program. Dr. Riley, the Section Chief directs the research program and, along with Dr. Sheila Cohen, (previous section chief and an experienced clinical researcher) meets regularly with the junior members of the team to discusses research and other issues.