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Biomedical subjects

Beth Stevens

Publications and source records attributed to Beth Stevens.

10 recordsLinked to original sources
PubMed2006

Charge of the right brigade? Communities, coverage, and care for the uninsured.

The Robert Wood Johnson Foundation's Communities in Charge (CIC) program funded projects in fourteen communities that aimed to expand health insurance coverage and improve care for their uninsured residents. Our examination of seven program sites suggests that despite solid community leadership and carefully crafted plans, political, economic, and organizational obstacles precluded much expansion of coverage and constrained reforms. Redistribution of financial and organizational resources among both mainstream and safety-net institutions in these communities was hard to achieve. CIC's record offers little evidence that communities are better equipped than are other sectors of U.S. society to solve the problem of uninsurance.

Community Health Planning↗
PubMed2006

Astrocytes promote myelination in response to electrical impulses.

Myelin, the insulating layers of membrane wrapped around axons by oligodendrocytes, is essential for normal impulse conduction. It forms during late stages of fetal development but continues into early adult life. Myelination correlates with cognitive development and can be regulated by impulse activity through unknown molecular mechanisms. Astrocytes do not form myelin, but these nonneuronal cells can promote myelination in ways that are not understood. Here, we identify a link between myelination, astrocytes, and electrical impulse activity in axons that is mediated by the cytokine leukemia inhibitory factor (LIF). These findings show that LIF is released by astrocytes in response to ATP liberated from axons firing action potentials, and LIF promotes myelination by mature oligodendrocytes. This activity-dependent mechanism promoting myelination could regulate myelination according to functional activity or environmental experience and may offer new approaches to treating demyelinating diseases.

Action Potentials↗
PubMed2006

Cross-talk between growth factor and purinergic signalling regulates Schwann cell proliferation.

Axons provide multiple mitogenic signals to Schwann cells (SCs), yet at an appropriate stage of development, SCs stop dividing despite the mitogenic action of axolemma and growth factors. This implies that the effect of mitogens on cell proliferation may be context-dependent, having different effects on cell proliferation depending upon other signals in the extracellular environment. Recent research has shown that the effects of adenosine on SC proliferation depend upon the growth factor environment, and that the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) signalling pathway is an important point of integration between purinergic and growth factor signalling. In the absence of growth factors, adenosine is mitogenic and associated with stimulation of the ERK/MAPK pathway in SCs. However, in the presence of growth factors (platelet-derived growth factor or neuregulin), adenosine has the opposite effect, inhibiting proliferation and ERK/MAPK activation. Together these findings suggest a mechanism by which increased neural impulse activity could modulate growth factor signalling to both positively and negatively regulate SC proliferation before the onset of myelination.

Animals↗
PubMed2005

The value of experience: differences in knowledge among Medicare beneficiaries.

The Medicare Advantage program gives Medicare beneficiaries the opportunity to choose from an array of insurance options instead of receiving prescribed benefits. In 2006, beneficiaries who want prescription drug benefits will need to enroll in a Medicare managed care plan or a private prescription drug plan. To examine awareness and use of Medicare information programs, and the extent to which these programs are associated with beneficiary knowledge about Medicare and managed care, we conducted a national survey of Medicare beneficiaries six to 12 months after the nationwide mailing of the Medicare & You 2000 handbook. Beneficiary information-gathering behavior and experience with Medicare managed care were more highly associated with knowledge about Medicare managed care than formal education, age, income, or membership in a managed care plan before enrolling in Medicare. Practical life experience appears to outweigh traditional factors in beneficiary knowledge of Medicare and managed care.

Aged↗
PubMed2004

Adenosine: an activity-dependent axonal signal regulating MAP kinase and proliferation in developing Schwann cells.

Nonsynaptic release of ATP from electrically stimulated dorsal root gangion (DRG) axons inhibits Schwann cell (SC) proliferation and arrests SC development at the premyelinating stage, but the specific types of purinergic receptor(s) and intracellular signaling pathways involved in this form of neuron-glia communication are not known. Recent research shows that adenosine is a neuron-glial transmitter between axons and myelinating glia of the CNS. The present study investigates the possibility that adenosine might have a similar function in communicating between axons and premyelinating SCs. Using a combination of pharmacological and molecular approaches, we found that mouse SCs in culture express functional adenosine receptors and ATP receptors, a far more complex array of purinergic receptors than thought previously. Adenosine, but not ATP, activates ERK/MAPK through stimulation of cAMP-linked A2(A) adenosine receptors. Both ATP and adenosine inhibit proliferation of SCs induced by platelet-derived growth factor (PDGF), via mechanisms that are partly independent. In contrast to ATP, adenosine failed to inhibit the differentiation of SCs to the O4+ stage. This indicates that, in addition to ATP, adenosine is an activity-dependent signaling molecule between axons and premyelinating Schwann cells, but that electrical activity, acting through adenosine, has opposite effects on the differentiation of myelinating glia in the PNS and CNS.

Journal Article↗
PubMed2003

How seniors learn.

The learning capacity of older adults has direct, practical implications for professionals trying to educate older people and their families about health-care services and benefits, especially Medicare. In this brief, we discuss the issue of how older people learn, exploring research from the field of cognitive aging. We also offer some tips for how you can adapt your educational programs and materials to build on your clients' cognitive strengths and compensate for some of the losses that can occur with aging.

Aged↗
PubMed2002

Adenosine: a neuron-glial transmitter promoting myelination in the CNS in response to action potentials.

Neuronal activity influences myelination of the brain, but the molecular mechanisms involved are largely unknown. Here, we report that oligodendrocyte progenitor cells (OPCs) express functional adenosine receptors, which are activated in response to action potential firing. Adenosine acts as a potent neuron-glial transmitter to inhibit OPC proliferation, stimulate differentiation, and promote the formation of myelin. This neuron-glial signal provides a molecular mechanism for promoting oligodendrocyte development and myelination in response to impulse activity and may help resolve controversy on the opposite effects of impulse activity on myelination in the central and peripheral nervous systems.

Action Potentials↗
PubMed2002

Regulation of the cell cycle in normal and pathological glia.

Precise regulation of the glial cell cycle is essential during nervous system development and in response to injury, whereas disruption of cell cycle control is associated with malignant glial tumors and other nervous system diseases. The Ras signaling pathway plays a central role in regulating the mammalian cell cycle, and uncontrolled Ras signaling has been implicated in a wide range of human cancers, including malignant gliomas. Recent studies in glia have demonstrated that activation of Ras can either induce or inhibit proliferation through complex interactions among downstream signaling pathways impinging on cell cycle regulatory proteins. Studies in Schwann cells have begun to delineate the pathways by which Ras regulates the cell cycle in normal and pathological glia, and have identified promising targets for therapeutic intervention in the treatment of PNS and CNS malignant glial tumors.

Animals↗
PubMedDate not supplied

Gender differences across racial and ethnic groups in the quality of care for acute myocardial infarction and heart failure associated with comorbidities.

This paper provides important insights on gender differences across racial and ethnic groups in a Medicare population in terms of the quality of care received for acute myocardial infarction (AMI) and congestive heart failure (CHF) in association with diabetes or hypertension/end-stage renal disease (ESRD). Both race/ethnicity and gender are associated with differences in the diagnostic evaluation and treatment of Medicare recipients with these conditions. In the AMI group, non-Hispanic Black and Hispanic patients of both genders were less likely to receive aspirin or beta-blockers than non-Hispanic Whites. These differences persisted for Hispanic women and men even when they presented with ESRD or diabetes. Rates for smoking cessation counseling were among the lowest among non-Hispanic Blacks and Hispanics with AMI-diabetes and non-Hispanic blacks with AMI-hypertension/ESRD. Gender comparisons within racial groups for the AMI and AMI-diabetes groups show that among non-Hispanic Whites, women were less likely to receive aspirin and beta-blockers. No gender differences were noted among non-Hispanic Black and Hispanic Medicare recipients. In the CHF group, Hispanics were the racial/ethnic group least likely to have an assessment of left ventricular function (LVF), even if they had diabetes and had lower rates of angiotensin-converting enzyme inhibitor therapy or even if they had combined CHF-hypertension/ESRD. Gender comparisons in both the CHF and CHF-hypertension/ESRD groups show that non-Hispanic White women were less likely to have an LVF assessment than non-Hispanic White men. Among all subjects, having comorbidities with AMI was not associated with higher markers of quality cardiovascular care. Closing the many gaps in cardiovascular care must target the specific needs of women and men across racial and ethnic groups.

Black or African American↗