Arginine methylation of yeast mRNA-binding protein Npl3 directly affects its function, nuclear export, and intranuclear protein interactions

Arginine methylation can affect both nucleocytoplasmic transport and protein-protein interactions of RNA-binding proteins. These effects are seen in cells that lack the yeast hnRNP methyltransferase (HMT1), raising the question of whether effects on specific proteins are direct or indirect. The presence of multiple arginines in individual methylated proteins also raises the question of whether overall methylation or methylation of a subset of arginines affects protein function. We have used the yeast mRNA-binding protein Npl3 to address these questions in vivo. Matrix-assisted laser desorption/ionization Fourier transform mass spectrometry was used to identify 17 methylated arginines in Npl3 purified from yeast: whereas 10 Arg-Gly-Gly (RGG) tripeptides were exclusively dimethylated, variable levels off methylation were found for 5 RGG and 2 RG motif arginines. We constructed a set of Npl3 proteins in which subsets of the RGG arginines were mutated to lysine. Expression of these mutant proteins as the sole form of Npl3 specifically affected growth of a strain that requires Hmtl. Although decreased growth generally correlated with increased numbers of Arg-to-Lys mutations, lysine substitutions in the N terminus of the RGG domain showed more severe effects. Npl3 with all 15 RGG arginines mutated to lysine exited the nucleus independent of Hmtl, indicating a direct effect of methylation on Npl3 transport. These mutations also resulted in a decreased, methylation-independent interaction of Npl3 with transcription elongation factor Tho2 and inhibited Npl3 self-association. These results support a model in which arginine methylation facilitates Npl3 export directly by weakening contacts with nuclear proteins. © 2005 by The American Society for Biochemistry and Molecular Biology, Inc

The Spin of the Black Hole Microquasar XTE J1550-564 via the Continuum-Fitting and Fe-Line Methods

We measure the spin of XTE J1550-564 in two ways: by modelling the thermal continuum spectrum of the accretion disc, and independently by modeling the broad red wing of the reflection fluorescence Fe-K line. We find that the spin measurements conducted independently using both leading methods are in agreement with one another. For the continuum-fitting analysis, we use a data sample consisting of several dozen RXTE spectra, and for the Fe-K analysis, we use a pair of ASCA spectra from a single epoch. Our spin estimate for the black hole primary using the continuum-fitting method is -0.11 < a* < 0.71 (90 per cent confidence), with a most likely spin of a* = 0.34. In obtaining this result, we have thoroughly explored the dependence of the spin value on a wide range of model-dependent systematic errors and observational errors; our precision is limited by uncertainties in the distance and orbital inclination of the system. For the Fe-line method, our estimate of spin is a* = 0.55(+0.15,-0.22). Combining these results, we conclude that the spin of this black hole is moderate, a* = 0.49(+0.13,-0.20), which suggests that the jet of this microquasar is powered largely by its accretion disc rather than by the spin energy of the black hole.Comment: 19 pages, 15 figures, submitted to MNRAS, updated abstrac

Attitudinal Barriers to Analgesic Use among Patients with Substance Use Disorders

Attitudinal barriers towards analgesic use among primary care patients with chronic pain and substance use disorders (SUDs) are not well understood. We evaluated the prevalence of moderate to significant attitudinal barriers to analgesic use among 597 primary care patients with chronic pain and current analgesic use with 3 subscales from the Barriers Questionaire II: concern about side effects, fear of addiction, and worry about reporting pain to physicians. Concern about side effects was a greater barrier for those with opioid use disorders (OUDs) and non-opioid SUDs than for those with no SUD (OR (95% CI): 2.30 (1.44–3.68), P < 0.001 and 1.64 (1.02–2.65), P = 0.041, resp.). Fear of addiction was a greater barrier for those with OUDs as compared to those with non-opioid SUDs (OR (95% CI): 2.12 (1.04–4.30), P = 0.038) and no SUD (OR (95% CI): 2.69 (1.44–5.03), P = 0.002). Conversely, participants with non-opioid SUDs reported lower levels of worry about reporting pain to physicians than those with no SUD (OR (95% CI): 0.43 (0.24–0.76), P = 0.004). Participants with OUDs reported higher levels of worry about reporting pain than those with non-opioid SUDs (OR (95% CI): 1.91 (1.01–3.60), P = 0.045). Concerns about side effects and fear of addiction can be barriers to analgesic use, moreso for people with SUDs and OUDs

Knowledge, Attitudes, Practices and Beliefs about Medical Male Circumcision (MMC) among a Sample of Health Care Providers in Haiti

Background Haiti has the highest number of people living with HIV infection in the Caribbean/Latin America region. Medical male circumcision (MMC) has been recommended to help prevent the spread of HIV. We sought to assess knowledge, attitudes, practices and beliefs about MMC among a sample of health care providers in Haiti. Methods A convenience sample of 153 health care providers at the GHESKIO Centers in Haiti responded to an exploratory survey that collected information on several topics relevant to health providers about MMC. Descriptive statistics were calculated for the responses and multivariable logistic regression was conducted to determine opinions of health care providers about the best age to perform MMC on males. Bayesian network analysis and sensitivity analysis were done to identify the minimum level of change required to increase the acceptability of performing MMC at age less than 1 year. Results The sample consisted of medical doctors (31.0%), nurses (49.0%), and other health care professionals (20.0%). Approximately 76% showed willingness to offer MMC services if they received training. Seventy-six percent believed that their male patients would accept circumcision, and 59% believed infancy was the best age for MMC. More than 90% of participants said that MMC would reduce STIs. Physicians and nurses who were willing to offer MMC if provided with adequate training were 2.5 (1.15–5.71) times as likely to choose the best age to perform MMC as less than one year. Finally, if the joint probability of choosing “the best age to perform MMC” as one year or older and having the mistaken belief that MMC prevents HIV entirely is reduced by 63% then the probability of finding that performing MMC at less than one year acceptable to health care providers is increased by 35%. Conclusion Participants demonstrated high levels of knowledge and positive attitudes towards MMC. Although this study suggests that circumcision is acceptable among certain health providers in Haiti, studies with larger and more representative samples are needed to confirm this finding

Recently Acquired Toxoplasma gondii Infection, Brazil

Soil exposure, eating undercooked meat, and having children are risk factors for acute infection and high rate of eye disease

Endothelin-1 Predicts Hemodynamically Assessed Pulmonary Arterial Hypertension in HIV Infection.

BackgroundHIV infection is an independent risk factor for PAH, but the underlying pathogenesis remains unclear. ET-1 is a robust vasoconstrictor and key mediator of pulmonary vascular homeostasis. Higher levels of ET-1 predict disease severity and mortality in other forms of PAH, and endothelin receptor antagonists are central to treatment, including in HIV-associated PAH. The direct relationship between ET-1 and PAH in HIV-infected individuals is not well described.MethodsWe measured ET-1 and estimated pulmonary artery systolic pressure (PASP) with transthoracic echocardiography (TTE) in 106 HIV-infected individuals. Participants with a PASP ≥ 30 mmHg (n = 65) underwent right heart catheterization (RHC) to definitively diagnose PAH. We conducted multivariable analysis to identify factors associated with PAH.ResultsAmong 106 HIV-infected participants, 80% were male, the median age was 52 years and 77% were on antiretroviral therapy. ET-1 was significantly associated with higher values of PASP [14% per 0.1 pg/mL increase in ET-1, p = 0.05] and PASP ≥ 30 mmHg [PR (prevalence ratio) = 1.24, p = 0.012] on TTE after multivariable adjustment for PAH risk factors. Similarly, among the 65 individuals who underwent RHC, ET-1 was significantly associated with higher values of mean pulmonary artery pressure and PAH (34%, p = 0.003 and PR = 2.43, p = 0.032, respectively) in the multivariable analyses.ConclusionsHigher levels of ET-1 are independently associated with HIV-associated PAH as hemodynamically assessed by RHC. Our findings suggest that excessive ET-1 production in the setting of HIV infection impairs pulmonary endothelial function and contributes to the development of PAH

The Photopic Negative Response: An Objective Measure of Retinal Ganglion Cell Function in Patients With Leber's Hereditary Optic Neuropathy

Purpose: The photopic negative response (PhNR) is a slow negative component of a flash photopic full-field ERG that has been shown to be specific for retinal ganglion cell (RGC) activity. Direct evaluation of RGC function is desirable in patients with Leber's hereditary optic neuropathy (LHON) in which the loss of central acuity can make it difficult to monitor patients with standard metrics. The purpose of this study was to evaluate the use of PhNR as an objective noninvasive clinical metric in LHON.Methods: Full-field photopic ERG recordings were collected in subjects with the mt.11778G>A/ND4 LHON mutation using a red on blue stimulus. The PhNR was identified using a computer-based automated detection system, and data were manually examined to remove movement artifacts.Results: The PhNR amplitude was compared between controls (n = 13), carriers (n = 17), and affected (n = 6). Mean PhNR amplitude decreased significantly across groups (P < 0.0001). Post hoc Tukey's test revealed a significant decrease in PhNR amplitude between carriers and controls (P < 0.05) and between carriers and affected (P < 0.01).Conclusions: We are able to demonstrate that the PhNR amplitude is significantly decreased in patients affected by LHON compared to carriers in a well-described pedigree. Surprisingly, there was also a decrease in PhNR in carriers, suggesting potential subclinical RGC dysfunction in some carriers. This is important in patients affected with LHON who typically have a dense central scotoma. The PhNR may be a useful objective outcome measure for future clinical trials

A broad iron line in LMC X‐1

We present results from a deep Suzaku observation of the black hole in LMC X‐1, supplemented by coincident monitoring with the Rossi X‐ray Timing Explorer ( RXTE ). We identify broad relativistic reflection features in a soft disc‐dominated spectrum. A strong and variable power‐law component of emission is present which we use to demonstrate that enhanced Comptonization strengthens disc reflection. We constrain the spin parameter of the black hole by modelling LMC X‐1's broad reflection features. For our primary and most comprehensive spectral model, we obtain a high value for the spin: a * = 0 . 97 − 0.13 + 0.01 (68 per cent confidence). However, by additionally considering two alternate models as a measure of our systematic uncertainty, we obtain a broader constraint: a * = 0 . 97 − 0.25 + 0.02 . Both of these spin values are entirely consistent with a previous estimate of spin obtained using the continuum‐fitting method. At 99 per cent confidence, the reflection features require a * > 0.2. In addition to modelling the relativistically broadened reflection, we also model a sharp and prominent reflection component that provides strong evidence for substantial reprocessing in the wind of the massive companion. We infer that this wind sustains the ionization cone surrounding the binary system; this hypothesis naturally produces appropriate and consistent mass, time and length scales for the cone structure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94516/1/mnr22128.pd

Rivaroxaban for secondary stroke prevention in patients with embolic strokes of undetermined source : Design of the NAVIGATE ESUS randomized trial

Peer reviewe

Characterization of patients with embolic strokes of undetermined source in the NAVIGATE ESUS randomized trial

Background: The New Approach Rivaroxaban Inhibition of Factor Xa in a Global Trial vs. ASA to Prevent Embolism in Embolic Stroke of Undetermined Source (NAVIGATE-ESUS) trial is a randomized phase-III trial comparing rivaroxaban versus aspirin in patients with recent ESUS. Aims: We aimed to describe the baseline characteristics of this large ESUS cohort to explore relationships among key subgroups. Methods: We enrolled 7213 patients at 459 sites in 31 countries. Prespecified subgroups for primary safety and efficacy analyses included age, sex, race, global region, stroke or transient ischemic attack prior to qualifying event, time to randomization, hypertension, and diabetes mellitus. Results: Mean age was 66.9 ± 9.8 years; 24% were under 60 years. Older patients had more hypertension, coronary disease, and cancer. Strokes in older subjects were more frequently cortical and accompanied by radiographic evidence of prior infarction. Women comprised 38% of participants and were older than men. Patients from East Asia were oldest whereas those from Latin America were youngest. Patients in the Americas more frequently were on aspirin prior to the qualifying stroke. Acute cortical infarction was more common in the United States, Canada, and Western Europe, whereas prior radiographic infarctions were most common in East Asia. Approximately forty-five percent of subjects were enrolled within 30 days of the qualifying stroke, with earliest enrollments in Asia and Eastern Europe. Conclusions: NAVIGATE-ESUS is the largest randomized trial comparing antithrombotic strategies for secondary stroke prevention in patients with ESUS. The study population encompasses a broad array of patients across multiple continents and these subgroups provide ample opportunities for future research