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Biomedical subjects

Michael Weinrich

Publications and source records attributed to Michael Weinrich.

11 recordsLinked to original sources
PubMed2006

Voltage gating of VDAC is regulated by nonlamellar lipids of mitochondrial membranes.

Evidence is accumulating that lipids play important roles in permeabilization of the mitochondria outer membrane (MOM) at the early stage of apoptosis. Lamellar phosphatidylcholine (PC) and nonlamellar phosphatidylethanolamine (PE) lipids are the major membrane components of the MOM. Cardiolipin (CL), the characteristic lipid from the mitochondrial inner membrane, is another nonlamellar lipid recently shown to play a role in MOM permeabilization. We investigate the effect of these three key lipids on the gating properties of the voltage-dependent anion channel (VDAC), the major channel in MOM. We find that PE induces voltage asymmetry in VDAC current-voltage characteristics by promoting channel closure at cis negative applied potentials. Significant asymmetry is also induced by CL. The observed differences in VDAC behavior in PC and PE membranes cannot be explained by differences in the insertion orientation of VDAC in these membranes. Rather, it is clear that the two nonlamellar lipids affect VDAC gating. Using gramicidin A channels as a tool to probe bilayer mechanics, we show that VDAC channels are much more sensitive to the presence of CL than could be expected from the experiments with gramicidin channels. We suggest that this is due to the preferential insertion of VDAC into CL-rich domains. We propose that the specific lipid composition of the mitochondria outer membrane and/or of contact sites might influence MOM permeability by regulating VDAC gating.

Cardiolipins↗
PubMed2005

Rules for rehabilitation: an agenda for research.

Rehabilitation services have grown tremendously in the United States over the past 2 decades. Rules originally designed to guide Medicare reimbursement policies have had substantial effects in shaping the design of clinical services. This article traces the development of the most significant federal rules regarding rehabilitation, outlines the existing empirical evidence to support these rules, and discusses an agenda for research to improve the evidence for future policy development.

Biomedical Research↗
PubMed2005

Stroke rehabilitation in Switzerland versus the United States: a preliminary comparison.

This article compares the structure and process of rehabilitation for stroke patients at 2 internationally recognized rehabilitation hospitals, Klinik Valens ("Valens") in Switzerland and the William Donald Schaeffer Rehabilitation Hospital at Kernan ("Kernan") in the United States. Although the patient mix, structure, and process of rehabilitation were similar in many regards, there were some important differences. Most notably, on average, patients at the U.S. hospital were discharged from rehabilitation at approximately the same day poststroke that rehabilitation began in Switzerland. Patients remained in an inpatient setting an average of 40 days longer in Switzerland (for the combination of acute care and rehabilitation) and had significantly higher levels of functioning at discharge when compared to their U.S. counterparts. The authors' findings suggest that Europe may offer opportunities for rehabilitation research that would be difficult to duplicate in the United States and highlight policy-relevant questions for future studies aimed at developing efficient managed care systems for stroke survivors.

Activities of Daily Living↗
PubMed2004

Integrated health system for chronic disease management: lessons learned from France.

Rated number one in overall health system performance by the World Health Organization, the French spend less than half the amount on annual health care per capita that the United States spends. One contributing factor may be the attention given to chronic care. Since the mid-1900s, the French have developed regional community-based specialty systems for patients with chronic respiratory insufficiency or failure. COPD is the major cause of respiratory failure, the fourth leading cause of death in the United States, and its prevalence is increasing. Despite the clinical success of home mechanical ventilation and the potential for cost savings, providing such services in the United States remains a challenge. Lessons from France can inform the development of cost-effective chronic care models in the United States In this article, we review the French experience in the context of the United States Supreme Court's Olmstead decision, mandating that people in "more restrictive settings" such as nursing homes be offered community-based supports. We suggest that regional demonstration projects for patients with chronic respiratory failure or insufficiency can provide an important step in the development of effective chronic care systems in the United States

Aged↗
PubMed2003

Brain-computer interface technology: a review of the Second International Meeting.

This paper summarizes the Brain-Computer Interfaces for Communication and Control, The Second International Meeting, held in Rensselaerville, NY, in June 2002. Sponsored by the National Institutes of Health and organized by the Wadsworth Center of the New York State Department of Health, the meeting addressed current work and future plans in brain-computer interface (BCI) research. Ninety-two researchers representing 38 different research groups from the United States, Canada, Europe, and China participated. The BCIs discussed at the meeting use electroencephalographic activity recorded from the scalp or single-neuron activity recorded within cortex to control cursor movement, select letters or icons, or operate neuroprostheses. The central element in each BCI is a translation algorithm that converts electrophysiological input from the user into output that controls external devices. BCI operation depends on effective interaction between two adaptive controllers, the user who encodes his or her commands in the electrophysiological input provided to the BCI, and the BCI that recognizes the commands contained in the input and expresses them in device control. Current BCIs have maximum information transfer rates of up to 25 b/min. Achievement of greater speed and accuracy requires improvements in signal acquisition and processing, in translation algorithms, and in user training. These improvements depend on interdisciplinary cooperation among neuroscientists, engineers, computer programmers, psychologists, and rehabilitation specialists, and on adoption and widespread application of objective criteria for evaluating alternative methods. The practical use of BCI technology will be determined by the development of appropriate applications and identification of appropriate user groups, and will require careful attention to the needs and desires of individual users.

Algorithms↗
PubMed2002

Computerized approaches to communication retraining after stroke.

Augmentative and alternative communication (AAC) strategies traditionally have been designed for individuals for whom oral speech is not a viable option. Common clinical practice has expanded AAC use to a tool for cognitive retraining or remediation. Although technologic developments offer the potential for vastly improved communication and inclusion for some individuals with severe communication disorders, technology alone does not result in successful communication. Although AAC interventions have become increasingly common across the age range, the research base underlying the design of AAC technology, intervention strategies, and treatment potential across communication disorders remains quite limited. To move beyond the traditional application of AAC strategies as a communication modality for persons with severe motor disorders to applications for persons with cognitive/linguistic disorders, three interrelated areas of research requiring further investigations are discussed. These include the following: use of AAC as a research tool to provide theoretical insights into the nature of normal and impaired language and cognition; development of AAC strategies as treatment tools to facilitate language recovery and use (production and comprehension); and studies that evaluate the efficacy of applying AAC strategies as communication modalities for individuals with acquired cognitive/linguistic communication disorders.

Clinical Trials as Topic↗
PubMed2002

Clinical trials in head injury.

Traumatic brain injury (TBI) remains a major public health problem globally. In the United States the incidence of closed head injuries admitted to hospitals is conservatively estimated to be 200 per 100,000 population, and the incidence of penetrating head injury is estimated to be 12 per 100,000, the highest of any developed country in the world. This yields an approximate number of 500,000 new cases each year, a sizeable proportion of which demonstrate significant long-term disabilities. Unfortunately, there is a paucity of proven therapies for this disease. For a variety of reasons, clinical trials for this condition have been difficult to design and perform. Despite promising pre-clinical data, most of the trials that have been performed in recent years have failed to demonstrate any significant improvement in outcomes. The reasons for these failures have not always been apparent and any insights gained were not always shared. It was therefore feared that we were running the risk of repeating our mistakes. Recognizing the importance of TBI, the National Institute of Neurological Disorders and Stroke (NINDS) sponsored a workshop that brought together experts from clinical, research, and pharmaceutical backgrounds. This workshop proved to be very informative and yielded many insights into previous and future TBI trials. This paper is an attempt to summarize the key points made at the workshop. It is hoped that these lessons will enhance the planning and design of future efforts in this important field of research.

Brain Injuries↗
PubMed2002

Narrative and procedural discourse production by severely aphasic patients.

Five cbronically aphasic subjects were trained on a computerized iconographic communication system (C-VIC). Their performance in producing single sentences scripts. and narratives was assessed using both spoken English and C-VIC. The requisite vocabulary necessary and the narrative complexity of the target productions were controlled. Subject performance using C-VIC indicates that the ability to construct discourse at the macrostructural level is largely intact. Despite significant improvements in spoken production after C-VIC training, especially at the single sentence level, the subjects' spoken discourse remains severely impaired by their failures at the microlinguistic level. These results point to the limits of currently available approaches to the remediation of aphasia and suggest avenues for future research.

Aged↗