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Search Results: 1 - 10 of 401186 matches for " M. M. Briley "
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Noradrenergic symptom cluster in depression
Montgomery S,Briley M
Neuropsychiatric Disease and Treatment , 2011,
Abstract: Stuart Montgomery1, Mike Briley21Imperial College School of Medicine, London, UK; 2NeuroBiz Consulting and Communication, Castres, FranceDepression is characterized by a wide range of diverse symptoms, the severity of which can be quantified by various depression rating scales, such as the Montgomery Asberg Depression Rating Scale. Analyses of the individual items of this scale in patients treated with the selective serotonin reuptake inhibitors (SSRIs) have shown that not all items respond equally or with the same time of onset of improvement (Table 1).1,2 The items which respond less well or more slowly with SSRIs include lassitude, loss of energy, retardation of thoughts or actions, as well as concentration difficulties and loss of alertness. The loss of interest or pleasure that depressed patients experience (anhedonia) also responds poorly to SSRIs, and patients often complain of emotional indifference or blunting. Certain sleep difficulties are sometimes worsened by SSRIs. Appetite loss can be aggravated by certain SSRIs, an effect which can be made worse by nausea at the beginning of treatment.
The noradrenergic symptom cluster: clinical expression and neuropharmacology
Blier P,Briley M
Neuropsychiatric Disease and Treatment , 2011,
Abstract: Pierre Blier1, Mike Briley21Institute of Mental Health Research, University of Ottawa, Ottawa, Ontario, Canada; 2NeuroBiz Consulting and Communication, Castres, FranceAbstract: Signs and symptoms of depression can be linked to one or more monoaminergic systems, specifically the norepinephrine (NE), the dopamine (DA), and the serotonin (5-HT) systems. In particular, the modulation of energy, vigilance, and arousal can be directly linked to the NE system. There is, however, a great deal of overlap in the modulation of the symptoms of depression between these monoaminergic systems. There are considerable reciprocal interactions between the NE, DA, and the 5-HT systems. When using a selective serotonin reuptake inhibitor (SSRI), for example, 5-HT transmission is enhanced, but at the same time there is a dampening of the activity of NE and DA neurons through inhibitory 5-HT2A and 5-HT2C receptors, respectively. This could explain the residual symptoms of fatigue, lack of energy, and anhedonia, often seen after patients present an overall positive response to a SSRI. Using a dual 5-HT and NE reuptake inhibitor (SNRI), such as milnacipran, would result in an additional increase in NE activity. Futhermore, inhibiting NE reuptake increases DA availability in the frontal cortex since DA is mainly cleared by the NE transporters in several brain regions. A risk inherent in increased NE activity is that of provoking anxiety. This is avoided however by the attenuation of the phasic reactivity of the firing of NE neurons through prolonged administration of SSRI and SNRI.Keywords: norepinephrine, dopamine, serotonin, residual symptoms, norepinephrine paradox
The importance of norepinephrine in depression
Moret C,Briley M
Neuropsychiatric Disease and Treatment , 2011,
Abstract: Chantal Moret, Mike BrileyNeuroBiz Consulting and Communication, Castres, FranceAbstract: Depression is one of the most common psychological diseases with significant potential morbidity and mortality. Although the underlying pathophysiology of depression has not been clearly defined, preclinical and clinical evidence suggest disturbances in serotonin (5-HT), norepinephrine (NE), and dopamine (DA) neurotransmission in the central nervous system. Virtually all currently available antidepressants act on one or more of the following mechanisms: inhibition of reuptake of 5-HT or NE (and DA), antagonism of inhibitory presynaptic 5-HT or NE receptors, or inhibition of monoamine oxidase. All of these mechanisms result in an enhanced neurotransmission of 5-HT and/or NE. Evidence for the involvement of NE in depression is abundant, and recent studies on neuronal pathways and symptoms highlight the specific role of NE in this disorder. NE plays a determinant role in executive functioning regulating cognition, motivation, and intellect, which are fundamental in social relationships. Social dysfunction is possibly one of the most important factors affecting the quality of life in depressed patients.Keywords: serotonin, antidepressants, neurotransmission, symptoms
Calibration of the CH and CN Variations Among Main Sequence Stars in M71 and in M13
Michael M. Briley,Judith G. Cohen
Physics , 2001, DOI: 10.1086/321115
Abstract: An analysis of the CN and CH band strengths measured in a large sample of M71 and M13 main sequence stars by Cohen (1999a,b) is undertaken using synthetic spectra to quantify the underlying C and N abundances. In the case of M71 it is found that the observed CN and CH band strengths are best matched by the {\it{identical}} C/N/O abundances which fit the bright giants, implying: 1) little if any mixing is taking place during red giant branch ascent in M71, and 2) a substantial component of the C and N abundance inhomogeneities is in place before the main sequence turn-off. The unlikelihood of mixing while on the main sequence requires an explanation for the abundance variations which lies outside the present stars (primordial inhomogeneities or intra-cluster self enrichment). For M13 it is shown that the 3883\AA CN bands are too weak to be measured in the spectra for any reasonable set of expected compositions. A similar situation exists for CH as well. However, two of the more luminous program stars do appear to have C abundances considerably greater than those found among the bright giants thereby suggesting deep mixing has taken place on the M13 red giant branch.
DDO Photometry of M71: Carbon and Nitrogen Patterns Among Evolving Giants
M. M. Briley,G. H. Smith,C. F. Claver
Physics , 2001, DOI: 10.1086/323446
Abstract: We present V, B-V, and DDO C(41-42) and C(42-45) photometry for a sample of 75 red giants down to M_V = +2 in the relatively metal-rich Galactic globular cluster M71. The C(41-42) colors reveal a bimodal distribution of CN band strengths generally anticorrelated with CH band strength as measured by the C(42-45) color. Both DDO colors agree well with those found in 47 Tucanae -- a nearby globular cluster of similar metallicity -- and suggest nearly identical C and N abundance patterns among the giants of both clusters. A comparison with synthetic DDO colors demonstrates that little change in surface C or N abundance is required to match the colors of the M71 giants over the entire luminosity range observed. Apparently like 47 Tuc (a cluster of much greater mass and central concentration), M71 exhibits an abundance pattern which cannot be solely the result of internal mixing.
The increasing burden of depression
Lépine J-P,Briley M
Neuropsychiatric Disease and Treatment , 2011,
Abstract: Jean-Pierre Lépine1, Mike Briley21H pital Lariboisière Fernand Widal, Assistance Publique H pitaux de Paris Unité INSERM 705 CNRS UMR 8206, Université Paris Diderot, Paris, France; 2NeuroBiz Consulting and Communication, Castres, FranceAbstract: Recent epidemiological surveys conducted in general populations have found that the lifetime prevalence of depression is in the range of 10% to 15%. Mood disorders, as defined by the World Mental Health and the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, have a 12-month prevalence which varies from 3% in Japan to over 9% in the US. A recent American survey found the prevalence of current depression to be 9% and the rate of current major depression to be 3.4%. All studies of depressive disorders have stressed the importance of the mortality and morbidity associated with depression. The mortality risk for suicide in depressed patients is more than 20-fold greater than in the general population. Recent studies have also shown the importance of depression as a risk factor for cardiovascular death. The risk of cardiac mortality after an initial myocardial infarction is greater in patients with depression and related to the severity of the depressive episode. Greater severity of depressive symptoms has been found to be associated with significantly higher risk of all-cause mortality including cardiovascular death and stroke. In addition to mortality, functional impairment and disability associated with depression have been consistently reported. Depression increases the risk of decreased workplace productivity and absenteeism resulting in lowered income or unemployment. Absenteeism and presenteeism (being physically present at work but functioning suboptimally) have been estimated to result in a loss of $36.6 billion per year in the US. Worldwide projections by the World Health Organization for the year 2030 identify unipolar major depression as the leading cause of disease burden. This article is a brief overview of how depression affects the quality of life of the subject and is also a huge burden for both the family of the depressed patient and for society at large.Keywords: epidemiology, DALY, mortality risk, economic burden, family burden, depression
Abundances in Stars from the Red Giant Branch Tip to the Near the Main Sequence in M71: I. Sample Selection, Observing Strategy and Stellar Parameters
Judith G. Cohen,Bradford B. Behr,Michael M. Briley
Physics , 2001, DOI: 10.1086/322100
Abstract: We present the sample for an abundance analysis of 25 members of M71 with luminosities ranging from the red giant branch tip to the upper main sequence. The spectra are of high dispersion and of high precision. We describe the observing strategy and determine the stellar parameters for the sample stars using both broad band colors and fits of H$\alpha$ profiles. The derived stellar parameters agree with those from the Yale$^2$ stellar evolutionary tracks to within 50 -- 100K for a fixed log g, which is within the level of the uncertainties.
C and N Abundances in Stars At the Base of the Red Giant Branch in M5
Judith G. Cohen,Michael M. Briley,Peter B. Stetson
Physics , 2001, DOI: 10.1086/340179
Abstract: We present an analysis of a large sample of moderate resolution Keck LRIS spectra of subgiant (V \sim 17.2) and fainter stars in the Galactic globular cluster M5 (NGC 5904) with the goal of deriving C and N abundances. Star-to-star stochastic variations with significant range in both [C/Fe] and [N/Fe] are found at all luminosities extending to the bottom of the RGB at M_V \sim +3. Similar variations in CH appear to be present in the main sequence turnoff spectra. There is no sign of a change in the behavior of C and N with evolutionary stage over the full range in luminosity of the RGB and SGB. The C and N abundances appear strongly anti-correlated, as would be expected from the CN-cycle processing of stellar material. Yet the present stars are considerably fainter than the RGB bump, the point at which deep mixing is believed to set in. On this basis, while the observed abundance pattern is consistent with proton capture nucleosynthesis, we infer that the site of the reactions is likely not within the present sample, but rather in a population of more massive (2 -- 5 M(Sun)) now defunct stars. The range of variation of the N abundances is very large and the sum of C+N increases as C decreases. To reproduce this requires the incorporation not only of CN but also of ON-processed material. Furthermore, the existence of this correlation is quite difficult to reproduce with an external mechanism such as ``pollution'' with material processed in a more massive AGB star, which mechanism is fundamentally stochastic in nature. We therefore suggest that although the internal mixing hypothesis has serious flaws,new theoretical insights are needed and it should not be ruled out yet. (abridged)
Carbon Abundances of Faint Stars in M13 - Evidence for Two Abundance Altering Mechanisms
Michael M. Briley,Judith G. Cohen,Peter B. Stetson
Physics , 2002, DOI: 10.1086/345095
Abstract: We present an analysis of CH band strengths in Keck LRIS spectra of a sample of 81 stars in M13 within 2 magnitudes of the main-sequence turnoff. The subgiants clearly exhibit a substantial (a factor of ~ 6) spread in [C/Fe]. Moreover, the bulk of the subgiants possess C abundances larger than those found among their more luminous counterparts. The turnoff stars themselves are too warm for appreciable CH formation, but the relatively small range in the observed CH band strength for stars just below the turnoff nevertheless translates into this same spread in [C/Fe]. Still fainter, the sample size is small, but the same range in [C/Fe] appears to be present. On the basis of these observations we suggest that a process external to the present stars has resulted in a substantial star-to-star dispersion in [C/Fe] (and possibly other light elements) among all stars in M13. In addition, the surface C abundances among the more luminous stars have been further modified by the operation of an internal deep-mixing mechanism during red giant branch ascent. The amplitude of the scatter we find in [C/Fe] at all luminosities may prove difficult to explain via accretion from intermediate mass AGB stars as the external "polluting" mechanism.
Anticorrelated CN and CH Variations on the 47 Tucanae Main-Sequence Turnoff
M. M. Briley,J. E. Hesser,R. A. Bell,M. Bolte,G. H. Smith
Physics , 1994, DOI: 10.1086/117229
Abstract: Observations of CN and CH band strengths among a random sample of main-sequence turn-off stars (+3.9 < MV < +4.6) in the globular cluster 47 Tuc (NGC 104, C0021-723) were made with the CTIO Argus fiber spectrograph for the purpose of determining the ratio of CN-strong to CN-weak stars and investigating the behavior of CH relative to CN. Of the 20 turn-off stars, 12 were found to be CN-strong while 8 appear to be CN-weak. This ratio of CN-strong to CN-weak stars is similar to the ratios found among the more luminous 47 Tuc stars and implies little change in the overall distribution of CN with evolutionary state, although the present sample size is small. A general anticorrelation between CN and CH is also observed in that the CN-weak main-sequence stars all (with one possible exception) exhibit strong CH bands - a trend similar to that found among the brighter stars. That these variations occur among such relatively un-evolved stars and that the overall CN distribution appears to be independent of evolutionary state presents serious challenges to internal or mixing theories of their origin. We therefore suggest that at least some component of the C and N abundance inhomogeneities observed among the brighter (more evolved) stars of this cluster appears to have been established prior to the commencement of evolution up the red giant branch.
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