Structural Synergy and Molecular Crosstalk between Bacterial Helicase Loaders and Replication Initiators

SummaryThe loading of oligomeric helicases onto replication origins marks an essential step in replisome assembly. In cells, dedicated AAA+ ATPases regulate loading, however, the mechanism by which these factors recruit and deposit helicases has remained unclear. To better understand this process, we determined the structure of the ATPase region of the bacterial helicase loader DnaC from Aquifex aeolicus to 2.7 Å resolution. The structure shows that DnaC is a close paralog of the bacterial replication initiator, DnaA, and unexpectedly shares an ability to form a helical assembly similar to that of ATP-bound DnaA. Complementation and ssDNA-binding assays validate the importance of homomeric DnaC interactions, while pull-down experiments show that the DnaC and DnaA AAA+ domains interact in a nucleotide-dependent manner. These findings implicate DnaC as a molecular adaptor that uses ATP-activated DnaA as a docking site for regulating the recruitment and correct spatial deposition of the DnaB helicase onto origins

Spectroscopy and dynamics of the hydrated electron at the water/air interface

The hydrated electron, e–(aq), has attracted much attention as a central species in radiation chemistry. However, much less is known about e–(aq) at the water/air surface, despite its fundamental role in electron transfer processes at interfaces. Using time-resolved electronic sum-frequency generation spectroscopy, the electronic spectrum of e–(aq) at the water/air interface and its dynamics are measured here, following photo-oxidation of the phenoxide anion. The spectral maximum agrees with that for bulk e–(aq) and shows that the orbital density resides predominantly within the aqueous phase, in agreement with supporting calculations. In contrast, the chemistry of the interfacial hydrated electron differs from that in bulk water, with e–(aq) diffusing into the bulk and leaving the phenoxyl radical at the surface. Our work resolves long-standing questions about e–(aq) at the water/air interface and highlights its potential role in chemistry at the ubiquitous aqueous interface

Measuring emotional support in family networks: Adapting the Family Network Method for individuals with a mild intellectual disability.

Informal supportive networks of individuals with intellectual disability have become increasingly important. The aim of this paper is to describe how the Family Network Method - Intellectual Disability (FNM-ID) offers a way to gather the perspective of people with mild intellectual disability on their family support. The FNM is designed to explore how individuals define their family contexts, and more specifically how they perceive existing supportive relationships in these contexts. By carefully piloting ways of questioning people with mild intellectual disability, systematic adaptations were made to the original FNM. Data obtained by the FNM-ID can be analysed using social network analysis. Thereby, the FNM-ID provides rich, theoretically significant information on emotional support in the family networks of individuals with mild intellectual disability. The FNM-ID is a useful and successfully adapted tool for other researchers and professionals to systematically explore the family support experiences of individuals with mild intellectual disability

Health state preferences are equivalent in the United States and Trinidad and Tobago

To derive preference weights in Trinidad and Tobago for Quality of Well-being Scale (QWB) health states in order to calculate QWB scores that can be compared to scores calculated from US-derived preference weights. The comparison was to determine whether the QWB scores from these different preference weights would lead to similar conclusions. We conducted in-person household interviews to elicit preferences for 65 health states using a probability sample of 235 adults from Port of Spain, Chaguanas and San Fernando, Trinidad and Tobago. A regression model with correction for within-person clustering of observations was used to obtain preference weights based on case judgments on a 0 (dead) to 10 (“perfect health”) scale. The independent variables were the components of the QWB entered as indicator (0, 1) variables. One hundred and nineteen (51%) respondents provided ratings. The respondents that provided ratings were demographically no different from those that did not. The QWB response patterns were very similar using Trinidad and US weights. The mean (SD) QWB score was 0.750 (0.130) for female respondents and 0.784 (0.125) for male respondents using Trinidad coefficients (t 2, 233 = −2.05, P = 0.04) and 0.747 (0.131) for female respondents and 0.783 (0.126) for male respondents using US weights (t 2, 233 = −2.17, P = 0.03). Overall, we found the US and Trinidad and Tobago weights were highly similar and that the choice of either set of weights would lead to similar conclusions

Comparing the measurement equivalence of EQ-5D-5L across different modes of administration

Background: Interest in collecting Patient Reported Outcomes using electronic methods such as mobile phones has increased in recent years. However there is debate about the level of measurement equivalence between the traditional paper and newer electronic modes. Information about the acceptability of the electronic versions to respondents is also required. The aim of this study is to compare the equivalence of delivering a widely used generic measure of health status (EQ-5D-5L) across two administration modes (paper and mobile phone). Methods: Respondents from a research cohort of people in South Yorkshire were identified, and randomly allocated to one of two administration modes (paper vs. mobile phone) based on stratifications for age and gender (and across a range of self-reported health conditions). A parallel group design was used where each respondent only completed EQ-5D-5L using one of the modes. In total, 70 respondents completed the measure in the mobile phone arm, and 66 completed the standard paper version. Follow up usability questions were also included to assess the acceptability of the mobile version of EQ-5D-5L. Measurement equivalence was compared at the dimension, utility score and visual analogue scale level using chi square analysis and ANOVA, and by comparing mean differences to an estimated minimally important difference value. Results: Response rates were higher in the mobile arm. The mean EQ-5D-5L utility and VAS scores, and the frequency of respondents endorsing individual EQ-5D-5L dimension response levels did not significantly differ across the administration modes. The majority of the mobile arm agreed that the mobile version of EQ-5D-5L was easy to complete, and that the phone was easy to use, and that they would complete mobile health measures again. Conclusions: Completing health status measures such as EQ-5D using mobile phones produces equivalent results to more traditional methods, but with added benefits (for example lessening the burden of data entry). Respondents are positive towards completing questionnaires using these methods. The results provide evidence that electronic measures are valid for use to collect data in a range of settings including clinical trials, routine care, and in health diary settings

Psychometric Properties of an Arabic Pain Anxiety Symptoms Scale-20 (PASS-20) in Healthy Volunteers and Patients Attending a Physiotherapy Clinic.

PURPOSE: The aim of this study was to cross-culturally adapt the PASS-20 questionnaire for use in Libya. METHODS: Participants were 71 patients (42 women) attending the physiotherapy clinic, Ibn Sina Hospital, Sirt, Libya for management of persistent pain and 137 healthy unpaid undergraduate students (52 women) from the University of Sirt, Libya. The English PASS-20 was translated into Arabic. Patients completed the Arabic PASS-20 and the Arabic Pain Rating Scales on two occasions separated by a 14-day interval. Healthy participants completed the Arabic PASS-20 on one occasion. RESULTS: The internal consistency (ICC) for pain patient and healthy participant samples yielded a good reliability for the total score, cognitive anxiety, fear of pain, and physiological anxiety. The test-retest reliability of the Arabic PASS-20 score showed high reliability for the total score (ICC = 0.93, p < 0.001), escape/avoidance (ICC = 0.93, p < 0.001), fear of pain (ICC = 0.94, p < 0.001), and physiological anxiety subscales (ICC = 0.96, p < 0.001) and good reliability for the cognitive anxiety (ICC = 0.85, p < 0.001). Inspection of the Promax rotation showed that each factor comprised of five items were consistent with the theoretical constructs of the original PASS-20 subscales. CONCLUSION: The Arabic PASS-20 retained internal consistency and reliability with the original English version and can be used to measure pain anxiety symptoms in both pain and healthy individual samples in Libya

Reevaluating the imaging definition of tumor progression: perfusion MRI quantifies recurrent glioblastoma tumor fraction, pseudoprogression, and radiation necrosis to predict survival

INTRODUCTION: Contrast-enhanced MRI (CE-MRI) represents the current mainstay for monitoring treatment response in glioblastoma multiforme (GBM), based on the premise that enlarging lesions reflect increasing tumor burden, treatment failure, and poor prognosis. Unfortunately, irradiating such tumors can induce changes in CE-MRI that mimic tumor recurrence, so called post treatment radiation effect (PTRE), and in fact, both PTRE and tumor re-growth can occur together. Because PTRE represents treatment success, the relative histologic fraction of tumor growth versus PTRE affects survival. Studies suggest that Perfusion MRI (pMRI)–based measures of relative cerebral blood volume (rCBV) can noninvasively estimate histologic tumor fraction to predict clinical outcome. There are several proposed pMRI-based analytic methods, although none have been correlated with overall survival (OS). This study compares how well histologic tumor fraction and OS correlate with several pMRI-based metrics. METHODS: We recruited previously treated patients with GBM undergoing surgical re-resection for suspected tumor recurrence and calculated preoperative pMRI-based metrics within CE-MRI enhancing lesions: rCBV mean, mode, maximum, width, and a new thresholding metric called pMRI–fractional tumor burden (pMRI-FTB). We correlated all pMRI-based metrics with histologic tumor fraction and OS. RESULTS: Among 25 recurrent patients with GBM, histologic tumor fraction correlated most strongly with pMRI-FTB (r = 0.82; P < .0001), which was the only imaging metric that correlated with OS (P<.02). CONCLUSION: The pMRI-FTB metric reliably estimates histologic tumor fraction (i.e., tumor burden) and correlates with OS in the context of recurrent GBM. This technique may offer a promising biomarker of tumor progression and clinical outcome for future clinical trials

Demographic variation in incidence of adult glioma by subtype, United States, 1992-2007

<p>Abstract</p> <p>Background</p> <p>We hypothesized that race/ethnic group, sex, age, and/or calendar period variation in adult glioma incidence differs between the two broad subtypes of glioblastoma (GBM) and non-GBM. Primary GBM, which constitute 90-95% of GBM, differ from non-GBM with respect to a number of molecular characteristics, providing a molecular rationale for these two broad glioma subtypes.</p> <p>Methods</p> <p>We utilized data from the Surveillance, Epidemiology, and End Results Program for 1992-2007, ages 30-69 years. We compared 15,088 GBM cases with 9,252 non-GBM cases. We used Poisson regression to calculate adjusted rate ratios and 95% confidence intervals.</p> <p>Results</p> <p>The GBM incidence rate increased proportionally with the 4^thpower of age, whereas the non-GBM rate increased proportionally with the square root of age. For each subtype, compared to non-Hispanic Whites, the incidence rate among Blacks, Asians/Pacific Islanders, and American Indians/Alaskan Natives was substantially lower (one-fourth to one-half for GBM; about two-fifths for non-GBM). Secondary to this primary effect, race/ethnic group variation in incidence was significantly less for non-GBM than for GBM. For each subtype, the incidence rate was higher for males than for females, with the male/female rate ratio being significantly higher for GBM (1.6) than for non-GBM (1.4). We observed significant calendar period trends of increasing incidence for GBM and decreasing incidence for non-GBM. For the two subtypes combined, we observed a 3% decrease in incidence between 1992-1995 and 2004-2007.</p> <p>Conclusions</p> <p>The substantial difference in age effect between GBM and non-GBM suggests a fundamental difference in the genesis of primary GBM (the driver of GBM incidence) versus non-GBM. However, the commonalities between GBM and non-GBM with respect to race/ethnic group and sex variation, more notable than the somewhat subtle, albeit statistically significant, differences, suggest that within the context of a fundamental difference, some aspects of the complex process of gliomagenesis are shared by these subtypes as well. The increasing calendar period trend of GBM incidence coupled with the decreasing trend of non-GBM incidence may at least partly be due to a secular trend in diagnostic fashion, as opposed to real changes in incidence of these subtypes.</p