226 research outputs found
The two-hour orbit of a binary millisecond X-ray pulsar
Typical radio pulsars are magnetized neutron stars that are born rapidly
rotating and slow down as they age on time scales of 10 to 100 million years.
However, millisecond radio pulsars spin very rapidly even though many are
billions of years old. The most compelling explanation is that they have been
"spun up" by the transfer of angular momentum during accretion of material from
a companion star in so-called low-mass X-ray binary systems, LMXBs. (LMXBs
consist of a neutron star or black hole accreting from a companion less than
one solar mass.) The recent detection of coherent X-ray pulsations with a
millisecond period from a suspected LMXB system appears to confirm this link.
Here we report observations showing that the orbital period of this binary
system is two hours, which establishes it as an LMXB. We also find an apparent
modulation of the X-ray flux at the orbital period (at the two per cent level),
with a broad minimum when the pulsar is behind this low-mass companion star.
This system seems closely related to the "black widow" millisecond radio
pulsars, which are evaporating their companions through irradiation. It may
appear as an eclipsing radio pulsar during periods of X-ray quiescence.Comment: 4 pages with 1 figure. Style files included. Fig. 2 deleted and text
revised. To appear in Nature. Press embargo until 18:00 GMT on 1998 July 2
Consensus on circulatory shock and hemodynamic monitoring. Task force of the European Society of Intensive Care Medicine.
OBJECTIVE: Circulatory shock is a life-threatening syndrome resulting in multiorgan failure and a high mortality rate. The aim of this consensus is to provide support to the bedside clinician regarding the diagnosis, management and monitoring of shock.
METHODS: The European Society of Intensive Care Medicine invited 12 experts to form a Task Force to update a previous consensus (Antonelli et al.: Intensive Care Med 33:575-590, 2007). The same five questions addressed in the earlier consensus were used as the outline for the literature search and review, with the aim of the Task Force to produce statements based on the available literature and evidence. These questions were: (1) What are the epidemiologic and pathophysiologic features of shock in the intensive care unit ? (2) Should we monitor preload and fluid responsiveness in shock ? (3) How and when should we monitor stroke volume or cardiac output in shock ? (4) What markers of the regional and microcirculation can be monitored, and how can cellular function be assessed in shock ? (5) What is the evidence for using hemodynamic monitoring to direct therapy in shock ? Four types of statements were used: definition, recommendation, best practice and statement of fact.
RESULTS: Forty-four statements were made. The main new statements include: (1) statements on individualizing blood pressure targets; (2) statements on the assessment and prediction of fluid responsiveness; (3) statements on the use of echocardiography and hemodynamic monitoring.
CONCLUSIONS: This consensus provides 44 statements that can be used at the bedside to diagnose, treat and monitor patients with shock
Disparity between skin perfusion and sublingual microcirculatory alterations in severe sepsis and septic shock: a prospective observational study
Objective: Measurement of central-to-toe temperature difference has been advocated as an index of severity of shock and as a guide for circulatory therapy in critically ill patients. However, septic shock, in contrast to other forms of shock, is associated with a distributive malfunction resulting in a disparity between vascular compartments. Although this disparity has been established between systemic and microcirculatory parameters, it is unclear whether such disparity exists between skin perfusion and microcirculation. To test this hypothesis of disparity, we simultaneously measured parameters of the two vascular compartments, in the early phase of sepsis. Design: Prospective observational study in patients with severe sepsis/septic shock in the first 6 h of ICU admission. Simultaneous measurements of central-to-toe temperature difference and sublingual microcirculatory orthogonal polarization spectral imaging, together with parameters of systemic hemodynamics. Setting: 22 bed mixed-ICU in a tertiary teaching hospital. Patients: 35 consecutive patients in a 12-month period. Measurements and results: In 35 septic patients and a median APACHE II score of 20, no correlation between central-to-toe temperature gradient and microvascular flow index was observed (r(s) =-0.08, p = 0.65). Also no significant correlation between temperature gradient/microvascular flow index and systemic hemodynamic parameters could be demonstrated. Conclusions: During the early phase of resuscitated severe sepsis and septic shock there appears to be no correlation between sublingual microcirculatory alterations and the central-to-toe temperature difference. This finding adds to the concept of a dispersive nature of blood flow under conditions of sepsis between microcirculatory and systemic hemodynamic
Binary and Millisecond Pulsars at the New Millennium
We review the properties and applications of binary and millisecond pulsars.
Our knowledge of these exciting objects has greatly increased in recent years,
mainly due to successful surveys which have brought the known pulsar population
to over 1300. There are now 56 binary and millisecond pulsars in the Galactic
disk and a further 47 in globular clusters. This review is concerned primarily
with the results and spin-offs from these surveys which are of particular
interest to the relativity community.Comment: 59 pages, 26 figures, 5 tables. Accepted for publication in Living
Reviews in Relativity (http://www.livingreviews.org
Distribution, size, shape, growth potential and extent of abdominal aortic calcified deposits predict mortality in postmenopausal women
Background: Aortic calcification is a major risk factor for death from cardiovascular disease. We investigated the relationship between mortality and the composite markers of number, size, morphology and distribution of calcified plaques in the lumbar aorta.Methods: 308 postmenopausal women aged 48-76 were followed for 8.3 ± 0.3 years, with deaths related to cardiovascular disease, cancer, or other causes being recorded. From lumbar X-rays at baseline the number (NCD), size, morphology and distribution of aortic calcification lesions were scored and combined into one Morphological Atherosclerotic Calcification Distribution (MACD) index. The hazard ratio for mortality was calculated for the MACD and for three other commonly used predictors: the EU SCORE card, the Framingham Coronary Heart Disease Risk Score (Framingham score), and the gold standard Aortic Calcification Severity score (AC24) developed from the Framingham Heart Study cohorts.Results: All four scoring systems showed increasing age, smoking, and raised triglyceride levels were the main predictors of mortality after adjustment for all other metabolic and physical parameters. The SCORE card and the Framingham score resulted in a mortality hazard ratio increase per standard deviation (HR/SD) of 1.8 (1.51-2.13) and 2.6 (1.87-3.71), respectively. Of the morphological x-ray based measures, NCD revealed a HR/SD >2 adjusted for SCORE/Framingham. The MACD index scoring the distribution, size, morphology and number of lesions revealed the best predictive power for identification of patients at risk of mortality, with a hazard ratio of 15.6 (p < 0.001) for the 10% at greatest risk of death.Conclusions: This study shows that it is not just the extent of aortic calcification that predicts risk of mortality, but also the distribution, shape and size of calcified lesions. The MACD index may provide a more sensitive predictor of mortality from aortic calcification than the commonly used AC24 and SCORE/Framingham point card systems
Relation between awareness of circulatory disorders and smoking in a general population health examination
BACKGROUND: Little is known about proportions of smokers who maintain smoking after they are aware of a circulatory disorder. The goal was to analyze the extent to which the number of circulatory disorders may be related to being a current smoker. METHODS: Cross-sectional survey study with a probability sample of residents in Germany investigated in health examination centers. Questionnaire data of 3,778 ever smoking participants aged 18 – 79 were used, questions included whether the respondent had ever had hypertension, myocardial infarction, other coronary artery disease, heart failure, stroke, other cerebrovascular disease, peripheral vascular disease, and venous thrombosis. Logistic regression was calculated for circulatory disorders and their number with current smoking as the dependent variable, and odds ratios (OR) are presented adjusted for physician contact, inpatient treatment, smoking cessation counseling, heavy smoking, exercise, overweight and obesity, school education, sex and age. RESULTS: Among ever smokers who had 1 circulatory disorder, 52.1 % were current smokers and among those who reported that they had 3 or more circulatory disorders 28.0 % were current smokers at the time of the interview. The adjusted odds of being a current smoker were lower for individuals who had ever smoked in life and had 2 or more central circulatory disorders, such as myocardial infarction, heart failure or stroke, than for ever smokers without central circulatory disorder (2 or more disorders: adjusted OR 0.6, 95 % confidence interval, CI, 0.4 to 0.8). CONCLUSION: Among those with central circulatory disorders, there is a substantial portion of individuals who smoke despite their disease. The data suggest that only a portion of smokers among the general population seems to be discouraged from smoking by circulatory disorders or its accompanying cognitive or emotional processes
A computer decision aid for medical prevention: a pilot qualitative study of the Personalized Estimate of Risks (EsPeR) system
BACKGROUND: Many preventable diseases such as ischemic heart diseases and breast cancer prevail at a large scale in the general population. Computerized decision support systems are one of the solutions for improving the quality of prevention strategies. METHODS: The system called EsPeR (Personalised Estimate of Risks) combines calculation of several risks with computerisation of guidelines (cardiovascular prevention, screening for breast cancer, colorectal cancer, uterine cervix cancer, and prostate cancer, diagnosis of depression and suicide risk). We present a qualitative evaluation of its ergonomics, as well as it's understanding and acceptance by a group of general practitioners. We organised four focus groups each including 6–11 general practitioners. Physicians worked on several structured clinical scenari os with the help of EsPeR, and three senior investigators leaded structured discussion sessions. RESULTS: The initial sessions identified several ergonomic flaws of the system that were easily corrected. Both clinical scenarios and discussion sessions identified several problems related to the insufficient comprehension (expression of risks, definition of familial history of disease), and difficulty for the physicians to accept some of the recommendations. CONCLUSION: Educational, socio-professional and organisational components (i.e. time constraints for training and use of the EsPeR system during consultation) as well as acceptance of evidence-based decision-making should be taken into account before launching computerised decision support systems, or their application in randomised trials
First nationwide survey on cardiovascular risk factors in Grand-Duchy of Luxembourg (ORISCAV-LUX)
BACKGROUND: The ORISCAV-LUX study is the first baseline survey of an on-going cardiovascular health monitoring programme in Grand-Duchy of Luxembourg. The main objectives of the present manuscript were 1) to describe the study design and conduct, and 2) to present the salient outcomes of the study, in particular the prevalence of the potentially modifiable and treatable cardiovascular disease risk factors in the adult population residing in Luxembourg. METHOD: ORISCAV-LUX is a cross-sectional study based on a random sample of 4496 subjects, stratified by gender, age categories and district, drawn from the national insurance registry of 18-69 years aged Luxembourg residents, assuming a response rate of 30% and a proportion of 5% of institutionalized subjects in each stratum. The cardiovascular health status was assessed by means of a self-administered questionnaire, clinical and anthropometric measures, as well as by blood, urine and hair examinations. The potentially modifiable and treatable risk factors studied included smoking, hypertension, dyslipidemia, diabetes mellitus, and obesity. Both univariate and multivariate statistical analyses used weighted methods to account for the stratified sampling scheme. RESULTS: A total of 1432 subjects took part in the survey, yielding a participation rate of 32.2%. This figure is higher than the minimal sample size of 1285 subjects as estimated by power calculation. The most predominant cardiovascular risk factors were dyslipidemia (69.9%), hypertension (34.5%), smoking (22.3%), and obesity (20.9%), while diabetes amounted 4.4%. All prevalence rates increased with age (except smoking) with marked gender differences (except diabetes). There was a significant difference in the prevalence of hypertension and of lipid disorders by geographic region of birth. The proportion of subjects cumulating two or more cardiovascular risk factors increased remarkably with age and was more predominant in men than in women (P<0.0001). Only 14.7% of men and 23.1% of women were free of any cardiovascular risk factor. High prevalence of non-treated CVRF, notably for hypertension and dyslipidemia, were observed in the study population. CONCLUSION: The population-based ORISCAV-LUX survey revealed a high prevalence of potentially modifiable and treatable cardiovascular risk factors among apparently healthy subjects; significant gender and age-specific differences were seen not only for single but also for combined risk factors. From a public health perspective, these preliminary findings stress the urgent need for early routine health examinations, preventive interventions and lifestyle behavioural changes, even in young asymptomatic adults, to decrease cardiovascular morbidity and mortality in Luxembourg
Bedside Sublingual Video Imaging of Microcirculation in Assessing Bacterial Infection in Cirrhosis
Bacterial infections are common in cirrhosis and can lead to life-threatening complications. Sidestream dark-field (SDF) imaging has recently emerged as a noninvasive tool for capturing real-time video images of sublingual microcirculation in critically ill patients with sepsis. The objective of this study was to assess the utility of SDF in determining underlying infection in patients with cirrhosis. Sublingual microcirculation was compared among patients with compensated cirrhosis (Group A, n = 13), cirrhosis without sepsis (Group B, n = 18), cirrhosis with sepsis (Group C, n = 14), and sepsis only (Group D, n = 10). The blood flow was semi-quantitatively evaluated in four equal quadrants in small (10–25 mm); medium (26–50 mm); and large (51–100 mm) sublingual capillaries. The blood flow was described as no flow (0), intermittent flow (1), sluggish flow (2), and continuous flow (3). The overall flow score or microvascular flow index (MFI) was measured for quantitative assessment of microcirculation and predicting power for concurrent infection in cirrhosis. Marked impairment was observed at all levels of microvasculature in Groups B and C when compared with Group A. This effect was restricted to small vessels only when Group B was compared with Group C. MFI < 1.5 was found to have highest sensitivity (100%) and specificity (100%) for infection in decompensated cirrhosis. SDF imaging of sublingual microcirculation can be a useful bedside diagnostic tool to assess bacterial infection in cirrhosis
CSAP localizes to polyglutamylated microtubules and promotes proper cilia function and zebrafish development
The diverse populations of microtubule polymers in cells are functionally distinguished by different posttranslational modifications, including polyglutamylation. Polyglutamylation is enriched on subsets of microtubules including those found in the centrioles, mitotic spindle, and cilia. However, whether this modification alters intrinsic microtubule dynamics or affects extrinsic associations with specific interacting partners remains to be determined. Here we identify the microtubule-binding protein centriole and spindle–associated protein (CSAP), which colocalizes with polyglutamylated tubulin to centrioles, spindle microtubules, and cilia in human tissue culture cells. Reducing tubulin polyglutamylation prevents CSAP localization to both spindle and cilia microtubules. In zebrafish, CSAP is required for normal brain development and proper left–right asymmetry, defects that are qualitatively similar to those reported previously for depletion of polyglutamylation-conjugating enzymes. We also find that CSAP is required for proper cilia beating. Our work supports a model in which polyglutamylation can target selected microtubule-associated proteins, such as CSAP, to microtubule subpopulations, providing specific functional capabilities to these populations.National Institutes of Health (U.S.) (Grant no. GM074746)American Cancer Society. Research Scholar Grant (121776)National Institute of General Medical Sciences (U.S.) (GM088313
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