23 research outputs found

    Wind anisotropies and GRB progenitors

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    We study the effect of wind anisotropies on the stellar evolution leading to collapsars. Rotating models of a 60 M⊙_\odot star with Ω/Ωcrit=0.75\Omega/\Omega_{\rm crit}=0.75 on the ZAMS, accounting for shellular rotation and a magnetic field, with and without wind anisotropies, are computed at ZZ=0.002 until the end of the core He-burning phase. Only the models accounting for the effects of the wind anisotropies retain enough angular momentum in their core to produce a Gamma Ray Burst (GRB). The chemical composition is such that a type Ic supernova event occurs. Wind anisotropies appear to be a key physical ingredient in the scenario leading to long GRBs.Comment: 5 pages, 4 figures, accepted for publication in A&A Lette

    Beyond the Evidence of the New Hypertension Guidelines. Blood pressure measurement – is it good enough for accurate diagnosis of hypertension? Time might be in, for a paradigm shift (I)

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    Despite widespread availability of a large body of evidence in the area of hypertension, the translation of that evidence into viable recommendations aimed at improving the quality of health care is very difficult, sometimes to the point of questionable acceptability and overall credibility of the guidelines advocating those recommendations. The scientific community world-wide and especially professionals interested in the topic of hypertension are witnessing currently an unprecedented debate over the issue of appropriateness of using different drugs/drug classes for the treatment of hypertension. An endless supply of recent and less recent "drug-news", some in support of, others against the current guidelines, justifying the use of selected types of drug treatment or criticising other, are coming out in the scientific literature on an almost weekly basis. The latest of such debate (at the time of writing this paper) pertains the safety profile of ARBs vs ACE inhibitors. To great extent, the factual situation has been fuelled by the new hypertension guidelines (different for USA, Europe, New Zeeland and UK) through, apparently small inconsistencies and conflicting messages, that might have generated substantial and perpetuating confusion among both prescribing physicians and their patients, regardless of their country of origin. The overwhelming message conveyed by most guidelines and opinion leaders is the widespread use of diuretics as first-line agents in all patients with blood pressure above a certain cut-off level and the increasingly aggressive approach towards diagnosis and treatment of hypertension. This, apparently well-justified, logical and easily comprehensible message is unfortunately miss-obeyed by most physicians, on both parts of the Atlantic. Amazingly, the message assumes a universal simplicity of both diagnosis and treatment of hypertension, while ignoring several hypertension-specific variables, commonly known to have high level of complexity, such as: - accuracy of recorded blood pressure and the great inter-observer variability, - diversity in the competency and training of diagnosing physician, - individual patient/disease profile with highly subjective preferences, - difficulty in reaching consensus among opinion leaders, - pharmaceutical industry's influence, and, nonetheless, - the large variability in the efficacy and safety of the antihypertensive drugs. The present 2-series article attempts to identify and review possible causes that might have, at least in part, generated the current healthcare anachronism (I); to highlight the current trend to account for the uncertainties related to the fixed blood pressure cut-off point and the possible solutions to improve accuracy of diagnosis and treatment of hypertension (II)

    Randomized controlled trial of a coordinated care intervention to improve risk factor control after stroke or transient ischemic attack in the safety net: Secondary stroke prevention by Uniting Community and Chronic care model teams Early to End Disparities (SUCCEED)

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    BACKGROUND: Recurrent strokes are preventable through awareness and control of risk factors such as hypertension, and through lifestyle changes such as healthier diets, greater physical activity, and smoking cessation. However, vascular risk factor control is frequently poor among stroke survivors, particularly among socio-economically disadvantaged blacks, Latinos and other people of color. The Chronic Care Model (CCM) is an effective framework for multi-component interventions aimed at improving care processes and outcomes for individuals with chronic disease. In addition, community health workers (CHWs) have played an integral role in reducing health disparities; however, their effectiveness in reducing vascular risk among stroke survivors remains unknown. Our objectives are to develop, test, and assess the economic value of a CCM-based intervention using an Advanced Practice Clinician (APC)-CHW team to improve risk factor control after stroke in an under-resourced, racially/ethnically diverse population. METHODS/DESIGN: In this single-blind randomized controlled trial, 516 adults (≥40 years) with an ischemic stroke, transient ischemic attack or intracerebral hemorrhage within the prior 90 days are being enrolled at five sites within the Los Angeles County safety-net setting and randomized 1:1 to intervention vs usual care. Participants are excluded if they do not speak English, Spanish, Cantonese, Mandarin, or Korean or if they are unable to consent. The intervention includes a minimum of three clinic visits in the healthcare setting, three home visits, and Chronic Disease Self-Management Program group workshops in community venues. The primary outcome is blood pressure (BP) control (systolic BP <130 mmHg) at 1 year. Secondary outcomes include: (1) mean change in systolic BP; (2) control of other vascular risk factors including lipids and hemoglobin A1c, (3) inflammation (C reactive protein [CRP]), (4) medication adherence, (5) lifestyle factors (smoking, diet, and physical activity), (6) estimated relative reduction in risk for recurrent stroke or myocardial infarction (MI), and (7) cost-effectiveness of the intervention versus usual care. DISCUSSION: If this multi-component interdisciplinary intervention is shown to be effective in improving risk factor control after stroke, it may serve as a model that can be used internationally to reduce race/ethnic and socioeconomic disparities in stroke in resource-constrained settings. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT01763203

    The Response of the Magnetosphere to a Solar Wind Density Pulse

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    Quantitative differences in TGF-β family members measured in small antral follicle fluids from women with or without PCO

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    CONTEXT: Members of the Transforming-Growth-Factor-β (TGF-β) family have been implicated in aberrant follicle development in women with polycystic ovaries (PCO). OBJECTIVE: Are there quantitative differences in the concentrations of TGF-β family members in fluid from small antral follicles (hSAF) from women with or without PCO? DESIGN SETTING: & Follicle fluids (FF) were collected from 4-11 mm hSAF obtained from women undergoing ovarian tissue cryopreservation for fertility preservation. PATIENTS: FFs from 16 women with PCO (FF=93) and 33 women without PCO (FF=92). MAIN OUTCOME MEASURES: Intrafollicular concentrations of Growth-Differentiation-Factor-9 (GDF9), Anti-Müllerian-Hormone (AMH), inhibin-A and -B, total inhibin, activin-A, -B and -AB, follistatin, follistatin-like-3, estradiol, and testosterone. RESULTS: Activin-B concentrations are reported for the first time in hSAF and concentrations were 10 times higher than activin-A and -AB. Activin-B showed significant associations to other growth factors. Concentrations of inhibin-A and -B were significantly lower in FF from women with PCO, especially in hSAF below 8 mm in diameter. AMH concentrations did not differ between the groups in hSAF below 8 mm, however, AMH remained high in hSAF above 8 mm in PCO but decreased in non-PCO women. Estradiol was significantly lower in FF from women with PCO and showed significant associations with AMH. Concentrations of GDF9 are reported for the first time showing significantly higher concentrations in PCO FF of follicles above 6 mm. CONCLUSIONS: Altered concentrations of TGF-β family members in hSAF from women with PCO highlight altered growth factor signaling as a potential mechanism for follicle growth arrest

    Intrafollicular concentrations of the oocyte-secreted factors GDF9 and BMP15 vary inversely in polycystic ovaries

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    Context The oocyte-secreted factors growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) play essential roles in follicle development and oocyte maturation, and aberrant regulation might contribute to the pathogenesis of polycystic ovary syndrome. Objective Are there measurable differences in concentrations of GDF9, BMP15, and the GDF9/BMP15 heterodimer in small antral follicle fluids from women with and without polycystic ovaries (PCO)? Design and Setting Follicle fluids (n = 356) were collected from 4- to 11-mm follicles in unstimulated ovaries of 87 women undergoing ovarian tissue cryopreservation for fertility preservation. Patients Twenty-seven women with PCO were identified and 60 women without PCO-like characteristics (non-PCO women) were matched according to age and follicle size. Main outcome measures Intrafollicular concentrations of GDF9, BMP15, GDF9/BMP15 heterodimer, anti-Mullerian hormone (AMH), inhibin-A and -B, total inhibin, activin-B and -AB, and follistatin were measured using enzyme-linked immunosorbent assays. Results The detectability of GDF9, BMP15, and the GDF9/BMP15 heterodimer were 100%, 94.4%, and 91.5%, respectively, and concentrations were significantly negatively correlated with increasing follicle size (P < 0.0001). GDF9 was significantly higher in women with PCO (PCO: 4230 ± 189 pg/mL [mean ± SEM], n = 188; non-PCO: 3498 ± 199 pg/mL, n = 168; P < 0.03), whereas BMP15 was lower in women with PCO (PCO: 431 ± 40 pg/mL, n = 125; non-PCO: 573 ± 55 pg/mL, n = 109; P = 0.10), leading to a significantly higher GDF9:BMP15 ratio in women with PCO (P < 0.01). Significant positive associations between BMP15 and AMH, activins, and inhibins in non-PCO women switched to negative associations in women with PCO. Conclusions Intrafollicular concentrations of GDF9 and BMP15 varied inversely in women with PCO reflecting an aberrant endocrine environment. An increased GDF9:BMP15 ratio may be a new biomarker for PCO
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