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Robert J Levine

Publications and source records attributed to Robert J Levine.

At least 19 recordsLinked to original sources
PubMed2006

Glucose-6-phosphate dehydrogenase-derived NADPH fuels superoxide production in the failing heart.

In the failing heart, NADPH oxidase and uncoupled NO synthase utilize cytosolic NADPH to form superoxide. NADPH is supplied principally by the pentose phosphate pathway, whose rate-limiting enzyme is glucose 6-phosphate dehydrogenase (G6PD). Therefore, we hypothesized that cardiac G6PD activation drives part of the excessive superoxide production implicated in the pathogenesis of heart failure. Pacing-induced heart failure was performed in eight chronically instrumented dogs. Seven normal dogs served as control. End-stage failure occurred after 28 +/- 1 days of pacing, when left ventricular end-diastolic pressure reached 25 mm Hg. In left ventricular tissue homogenates, spontaneous superoxide generation measured by lucigenin (5 microM) chemiluminescence was markedly increased in heart failure (1338 +/- 419 vs. 419 +/- 102 AU/mg protein, P < 0.05), as were NADPH levels (15.4 +/- 1.5 vs. 7.5 +/- 1.5 micromol/gww, P < 0.05). Superoxide production was further stimulated by the addition of NADPH. The NADPH oxidase inhibitor gp91(ds-tat) (50 microM) and the NO synthase inhibitor L-NAME (1 mM) both significantly lowered superoxide generation in failing heart homogenates by 80% and 76%, respectively. G6PD was upregulated and its activity higher in heart failure compared to control (0.61 +/- 0.10 vs. 0.24 +/- 0.03 nmol/min/mg protein, P < 0.05), while superoxide production decreased to normal levels in the presence of the G6PD inhibitor 6-aminonicotinamide. We conclude that the activation of myocardial G6PD is a novel mechanism that enhances NADPH availability and fuels superoxide-generating enzymes in heart failure.

6-Aminonicotinamide↗
PubMed2005

Investigative bronchoprovocation and bronchoscopy in airway diseases.

RATIONALE: Basic and clinical research strategies used for many lung diseases have depended on volunteer subjects undergoing bronchoscopy to establish access to the airways to collect biological specimens and tissue, perhaps with added bronchoprovocation in asthma syndromes. These procedures have yielded a wealth of important scientific information. Since the last critical review more than a decade ago, some of the techniques and applications have changed, and untoward events have occurred, raising safety concerns and increasing institutional review scrutiny. OBJECTIVES AND METHODS: To reappraise these investigational methods in the context of current knowledge, the National Heart, Lung, and Blood Institute and the National Institute of Allergy and Infectious Diseases of the National Institutes of Health convened a working group to review these procedures used for airway disease research, emphasizing asthma and chronic obstructive pulmonary disease. MAIN RESULTS: The group reaffirmed the scientific importance of investigative bronchoscopy and bronchoprovocation, even as less invasive technologies evolve. The group also considered the safety of bronchoscopy and bronchoprovocation with methacholine and antigen to be acceptable for volunteer subjects and patients, but stressed the need to monitor this closely and to emphasize proper training of participating medical research personnel. Issues were raised about vulnerable volunteers, especially children who need surrogates for informed consent. CONCLUSION: This review of investigative bronchoscopy and bronchoprovocation could serve as the basis for future guidelines for the use of these procedures in the United States.

Asthma↗
PubMed2003

The Declaration of Helsinki and clinical trials: a focus on placebo-controlled trials in schizophrenia.

OBJECTIVE: The authors' goal was to consider ethical approaches to placebo-controlled clinical trials in the light of the evolving Declaration of Helsinki, with special attention to applications to research on schizophrenia. METHOD: They review the Helsinki position on placebos, including the 2002 Clarification, exploring the potential negative effects of banning placebos in studies involving conditions for which at least partially effective treatments exist. The Clarification is examined as an approach to this issue that, in contrast to earlier formulations, better acknowledges the complexity of clinical research and the need for protocol-specific determinations. Placebo controls in schizophrenia studies are used to illustrate issues relevant to all clinical research on therapeutic interventions. RESULTS: The Helsinki Clarification provides a basis for operationalizing criteria for review of placebo use in clinical trials. Six criteria are proposed for judging the ethical acceptability of placebo controls, including the likelihood that the intervention being tested will have clinically significant advantages over existing treatments, the presence of compelling reasons for placebo use, subject selection that minimizes the possibility of serious adverse consequences, and a risk-versus-benefit analysis that favors the advantages from placebo use over the risks to subjects. CONCLUSIONS: The Helsinki Clarification constitutes an important advance in international approaches to placebo use, requiring protocol-by-protocol judgments on complex issues of clinical research ethics. When operationalized, it provides review boards with a useful methodology for reaching determinations on the appropriateness of placebo controls in particular studies.

Controlled Clinical Trials as Topic↗
PubMed2003

Is the use of placebo controls ethically permissible in clinical trials of agents intended to reduce fractures in osteoporosis?

Substantial progress has been made in developing treatments that reduce the risk of fractures in osteoporosis. However, available treatments are only partially effective, they are not widely used, and there is need to search for more effective means of fracture prevention. Currently known effective means of reducing fractures were found using randomized placebo-controlled trials. The use of placebo controls in clinical trials has been a subject of significant controversy in recent years. The Declaration of Helsinki revision of October 2000 caused great concern among clinical investigators about the future use of placebo controls if known effective therapeutic agents are available. A working group of ethicists, clinical trial design experts, and clinical investigators examined the current state of knowledge of osteoporosis treatment and trials. They concluded that if placebo controls put subjects at substantial risk of serious outcomes, they are not ethically permissible. Placebo controls in osteoporosis trials with fracture as the measured outcome are permissible only under narrowly defined conditions. Placebo controls may be used if competent, well-informed patients refuse approved therapies for sound reasons, there is a reasonable basis for substantial disagreement or lack of consensus among professionals about whether approved treatments are better than placebos, or subjects are refractory to known effective agents. Active control trials are permissible and desirable if they can be designed and conducted in ways that overcome the interpretive difficulties often associated with such trials.

Clinical Trials as Topic↗
PubMed2002

Research ethics for mental health science involving ethnic minority children and youths.

In response to U.S. Public Health Service projects promoting attention to disparities in the outcomes of mental health treatments, in July 2001, the American Psychological Association, the National Institute of Mental Health, and the Fordham University Center for Ethics Education convened a group of national leaders in bioethics, multicultural research, and ethnic minority mental health to produce a living document to guide ethical decision making for mental health research involving ethnic minority children and youths. This report summarizes the key recommendations distilled from these discussions.

Adolescent↗
PubMed2002

Pharmaceutical research involving the homeless.

Discussions of research involving vulnerable populations have left the homeless comparatively ignored. Participation by these subjects in drug studies has the potential to be upsetting, inconvenient, or unpleasant. Participation occasionally produces injury, health emergencies, and chronic health problems. Nonetheless, no ethical justification exists for the categorical exclusion of homeless persons from research. The appropriate framework for informed consent for these subjects of pharmaceutical research is not a single event of oral or written consent, but a multi-staged arrangement of disclosure, dialogue, and permission-giving. Payments and other rewards in biomedical research raise issues of whether it is ethical to offer inducements to the homeless in exchange for participation in drug studies. Such inducements can influence desperate persons who are seriously lacking in resources. The key is to strike a balance between a rate of payment high enough that it does not exploit subjects by underpayment and low enough that it does not create an irresistible inducement. This proposal does not underestimate the risks of research, which are often overestimated and need to be appraised in light of the relevant empirical literature.

Biomedical Research↗
PubMed1997

Some reflections on postgraduate medical ethics education.

Three goals of teaching medical ethics to physicians are reviewed. Components of a basic course in medical ethics are described with special attention to the roles of case conferences, ethics rounds, and role modeling. Obstacles to teaching ethics are also addressed.

Education, Medical↗
PubMed1992

Case vignette: premature surrender.

Three commentaries are offered on the following case: George, age 57, is a previously healthy man who recently underwent surgery for removal of a low-grade malignant thymoma. At the time of admission to the hospital, George stressed to the staff that he had long ago signed a "living will," which he renewed immediately after he learned of his cancer diagnosis. At the time of surgery, the tumor was found to extend into his mediastinum; although it was removable, this required revision of part of the sternum and grafting of the vessels feeding the heart chambers. Because of the resultant tissue damage and neuronal hyperactivity, George experienced postoperative episodes of cardiac arrhythmia and bronchospasm. Unanimous medical opinion was that this situation was a temporary problem that would resolve itself as the tissues healed. Until that time, however, it will be difficult to wean him from ventilatory support. When his stay in the intensive care unit became prolonged, George and his family began to insist that his status be changed to "do not resuscitate" and reminded the staff about his longstanding living will. All of this is happening despite the fact that the patient and family seemingly comprehend that although the short-term interventions are invasive, there is a high probability of a successful outcome. George's cancer prognosis is excellent, and, although he may well have an episode of life-threatening arrhythmia, he is likely to respond to resuscitation interventions. Once the immediate postoperative period is over, his potential for a long and productive life with full capacities is excellent. Consider the following questions: (a) Should George's expressed wishes be respected, or should the staff take additional steps to help him survive the postoperative period, even if that means violating his stated wishes? and (b) What steps might the staff follow in sorting through this problem?

Cognition↗