Justin Zivin - US grants

Stroke is the third most common cause of death in the United States, but there is no generally accepted specific therapy for most types of strokes. The search for pharmacological treatments that will minimize or prevent ischemic cerebral damage has been hindered by the lack of adequate animal models that simulate the clinical problem and are sufficiently sensitive and reproducible to allow adequate assessment of therapeutic efficacy. We have developed a series of coordinated models of embolic stroke that are specifically designed to allow us to determine, with considerable sensitivity, whether various pharmacological agents can improve neurological function. These methods will also allow us to estimate the frequency of complications that are likely to be encountered. In preliminary studies we found that tissue plasminogen activator (tPA), a thrombolytic agent, appears to substantially reduce neurological damage when given shortly after blood clots enter the cerebral circulation. Drug induced hemorrhagic complications were not observed. We propose to extend these studies to determine the most effective way of using tPA for treatment of acute embolic stroke. Since it is anticipated that tPA will be used in conjunction with heparin, we also propose to study the independent effects of heparin in these carefully controlled animal models and to determine whether any interactions can be anticipated in the combined use of these two agents. Finally, in most previous studies of stroke therapy, reversible ischemia models have been used. However, reversible ischemia represents only a portion of the clinical problem. The embolic stroke models we have developed allow us to study irreversible ischemia in a graded fashion. We propose to study drugs that have been shown to be effective for treatment of reversible ischemia in irreversible embolic stroke. If we can identify therapies that are effective in both types of models, there is an increased probability that these agents will produce beneficial results in clinical trials.

Acute damage to the central nervous system due to stroke, seizure disorders, and trauma are very common, and these problems are the most frequent neurologic causes of death and disability. It has been thought that several pathological molecular mechanisms are present in all of these disorders. In the past there have been few attempts to systematically study these precise relationships in a coordinated fashion. Previously, much attention was focussed on abnormalities of energy metabolism and blood flow. There can be little doubt that these factors are of considerable importance, but it is probable that they are not the sole causes of irreversible damage and play a relatively minor part in whatever recovery of function occurs. Our contention is that there are rapid alterations in protein structure and function in response to acute CNS insults that are critical to maintenance and restoration of neurologic integrity. Consequently, we have designed a program to investigate the similarities and differences in degenerative and regenerative responses to a variety of acute neurological insults. We will use 4 types of systems to model CNS injury: 1) surgical lesions in the fimbria-fornix pathway; 2) a seizure model produced by a lesion in this same area; 3) in vivo ischemia models; 4) a tissue culture ischemia model. The studies will consist of detailed examinations of the changes in protein phosphorylation, molecular genetics, and growth factors that occur a times of interest after the injury. We will also correlate physiological, histological, and behavioral alterations during the degenerative and recovery phases. Finally, we will use these initial observations to help us develop a framework for selection of therapies with transplants or pharmacological agents.

Acute damage to the central nervous system caused by stroke or trauma is the most frequent neurologic cause of death and disability. We hypothesize that the responses to these types of injury share common mechanisms that can serve as the basis for new therapeutic approaches. Since August 1990, when this program began, we have been cooperating in an effort to develop new types of therapies. The common theme we have been pursuing concerns the effects of neurotropic factors in models of central nervous system injury. At a cellular level, the impacts of stroke and traumatic injuries are similar. Both cause death and degeneration of some neurons and this is followed by reactive tissue changes. These reactions include sprouting of remaining neurons, and new growth of the supporting structures including glia and blood vessels. A class of substances known to respond to tissue damage in other parts of the body is growth factors (which include neurotrophic factors in the brain). These factors seem an especially important group since they are apparently required for the survival and maintenance of various types of neurons. Our ultimate goals are to develop methods of therapy that are likely to be more effective than prevailing techniques. Using animal models of central nervous system ischemia and trauma, we intend to: 1) determine the sequence of some critical events, at a biochemical level, occurring during the early phases of traumatic or ischemic injury, and 2) evaluate the effects of several types of neurotrophic factors and other related molecules in preventing damage and restoring function. We anticipate these studies will give us insights into the natural responses of the central nervous system to acute damage. These investigations will help us learn to augment the reparative processes, and inhibit dysfunctional responses. This will provide a scientific basis for selecting treatments. Some of these therapies should prevent or minimize neurologic damage at the time of injury. Other treatments have the potential to restore function to areas in which irreversible damage has already occurred.

disease /disorder model; brain injury; biomedical facility; neurosurgery; neuropharmacology; hippocampus; neurotrophic factors; spinal cord injury; laboratory rat; laboratory rabbit;

calmodulin dependent protein kinase; nervous system disorder chemotherapy; spinal cord injury; neurotrophic factors; cerebral ischemia /hypoxia; stroke; enzyme activity; disease /disorder model; reperfusion; brain disorder chemotherapy; brain injury; enzyme mechanism; phosphatase inhibitor; fibroblast growth factor; nonhuman therapy evaluation; neuropharmacology; posttranslational modifications; histopathology; laboratory rabbit;

This application requests support from NINDS for the 23rd Princeton Conference on Cerebrovascular Disease. For almost half a century, this biennial meeting has brought together basic and clinical investigators to discuss the current state of stroke research in depth. These meetings have helped to further understanding of stroke pathogenesis and development of new treatments. The 23rd Conference will be held from MArch21 to 23, 2002 in Coronado, California and will be hosted by the University of California San Diego. The conference will be limited to 150 attendees, including 35 junior investigators with special interest in cerebrovascular disease. Invitees will include clinical and bench scientists from around the world who are currently active in the field as well as key scientists from related disciplines. Special efforts will be made to identify and invite young scientists, women and under-represented minorities. Supplementary funds will be raised from private sources. The topics selected for the meeting represent key areas of basic and clinical cerebrovascular disease research that are currently important and, in many cases, controversial. The proceedings will be published in book form and disseminated as data files. Funds are also requested to help support the 24th and 25th Princeton Conferences to assist organization of future meetings. A structure is proposed to make it possible to maintain the high quality of meetings. The overall goal of the Conferences is to generate a vision of future directions in stroke research. Secure funding will greatly facilitate that objective.

The purpose of this Core is to develop the careers of clinically trained research scientists who will pursue translational research. We will do this using a training Fellowship. The Fellowship is intended for neurologists or other stroke specialists who wish to obtain post-graduate training in statistics, clinical trials design and execution, experimental design, and regulatory requirements. We believe that these elements are needed to develop a new generation of clinicians interested in stroke research and therapy.

The purpose of this Core is to develop the careers of clinically trained research scientists along tracks consonant with the translational research mission and goals of the UCSD SPOTRIAS Center. The training Fellowship is designed for neurologists or other stroke specialists who wish to obtain postgraduate training in statistics, clinical trials research methods, experimental design, and regulatory requirements. We believe that these elements are needed to develop a new generation of clinicians in translational stroke research and therapy who have sufficient skills and experience to become independent investigators. Training is available in two fundamental tracks: (1) clinical investigation of stroke therapies and (2) clinical and laboratory-based investigations of experimental stroke. The proportion of time spent in each area varies according to the trainees' levels of interest, and which track they choose. The UCSD SPOTRIAS Center offers 1- or 2-year training opportunities for PG-5 year or higher individuals. Training in all aspects of translational stroke research is provided, including staffing the Acute Stroke Team. Fellows gain experience with thrombolysis at all of our participating hospitals. Didactic lectures and seminars are offered in stroke epidemiology, prevention, biochemistry and molecular biology, therapy, statistics, and clinical trial design. If appropriate to prior training, laboratory research opportunities are available. The training is intended to provide all the knowledge and skills needed to establish a successful stroke center independently in the Fellow's post-training career. Substantive advancement in stroke care requires a cadre of young, skilled, active physician stroke specialists who will champion translational stroke research, ensuring rapid delivery of proven thrombolytic drugs and rapid development of new, promising adjunctive therapies. The UCSD Stroke Center Vascular Neurology Fellowship, which received ACGME accreditation in 2006, is designed to meet this urgent need. The Stroke Center annually recruits 2 physician-Fellows into a state-of-the-art program tailored to train future California and national leaders in stroke research and clinical care. To date 18 of the 19 graduates of the Stroke Center Fellows Program have become independent investigators or directors of dedicated regional stroke centers and have taken the lead in ensuring the widest possible application of proven and emerging stroke therapies.

There is evidence that low-energy infrared laser irradiation (LELI) can modify a number of disease states, and in preclinical and clinical studies we have developed preliminary data showing that stroke is among them. Since intravenous tissue plasminogen activator (tPA) is currently the only FDA-approved treatment for acute stroke, but increases the absolute rates of resolution of symptoms only from 25% to 38%, there is need for additional therapeutic modalities to further contain or eliminate brain damage. We have developed a series of animal cerebral ischemia and hemorrhage models that, when used in a coordinated fashion, should help identify many of the important variables in LELI that pertain to its viability, safety, and efficacy as an adjunctive therapy to thrombolysis. Toward this end, this project is designed to achieve the following specific aims: (1) Examine the interaction of LELI with tPA therapy using a rabbit small clot brain embolism model (SCEM), which allows monitoring of a behavioral endpoint. This approach should yield information that helps to predict the clinical outcome of LELI combined with tPA in humans. The study also examines whether there is any effect of LELI on tPA-induced intracerebral hemorrhaging in the large clot embolism model (LCEM), which will serve to warn or reassure clinical investigators about the potential of LELI side effects in stroke victims. (2) Conduct a phase II clinical trial to test safety and preliminarily assess efficacy of LELI in combination with tPA with acute stroke patients. One approach to stroke therapy, in addition to thrombolysis, is to provide some form of neuroprotection immediately after stroke onset to reduce the damage caused by lack of blood flow and increase the window of opportunity for thrombolytic therapy. A second strategy is to administer neuroprotection after initiation of thrombolysis to reduce damage while thrombolysis is occurring. A third is to induce neuroprotection after thrombolysis is complete to salvage tissue that would otherwise die even though blood flow has been restored. Finally, it would be useful to develop strategies to produce recovery of function that may restore at least some neurological function. LELI is potentially capable of producing all of these effects. The potential impact of the study results on acute stroke therapeutics is thus far-reaching.

DESCRIPTION (provided by applicant): Although acute ischemic stroke is now a treatable condition, thrombolysis, which is the only approved method, is far from perfect because of a short therapeutic window and significant side effect concerns (i.e. intracerebral hemorrhage [ICH]). Even thrombolytic therapy with tissue plasminogen activator (tPA) produces complete resolution of symptoms less than 40% of the time, so there is need for additional forms of therapy. Numerous neuroprotective strategies have been tested in clinical trials, but these methods have not been approved by the FDA for treating ischemic stroke. Transcranial laser therapy (TLT) with low energy infrared irradiation is a form of electromagnetic energy that is able to penetrate into the brain and react with the tissue to produce a series of biochemical reactions. Preliminary data from our laboratory provides evidence that TLT can reduce neurological damage in a rabbit model of embolic stroke. However, the best ways to deliver the energy have not been identified. There are three main objectives of these proposed experiments. First, even though TLT can improve behavioral function, the safety and efficacy profile of TLT has not been evaluated to any substantial extent. Since a wide variety of laser settings can be used to administer TLT, we will systematically alter power density, treatment duration, duty cycle and repeated therapy. We will also determine the effects of TLT on ICH because many ischemic strokes have a hemorrhagic component. Finally, since tPA therapy is the current standard stroke care, it is certain that TLT will be administered in combination with the thrombolytic. We will conduct combination studies to see if tPA and TLT produce beneficial effects when co-administered. Also, since the most feared complication of tPA therapy is ICH, we will investigate whether the TLT alters this relationship. Overall, in this research program, we will identify many important variables of TLT so that the device may be rapidly developed for the treatment of acute ischemic stroke beyond plans already in progress. RELEVANCE: If successful, this program will produce a new form of therapy that will be available to markedly increase the time that physicians will have to treat stroke victims after stroke onset. Since the treatment is probably quite safe, it will be readily adopted by most practitioners. Finally, transcranial laser therapy is in its infancy, and proof of safety and efficacy will markedly accelerate its development for a wide variety of disorders.