1,257 research outputs found
The frequency of epstein-barr virus infection and associated lymphoproliferative syndrome after transplantation and its manifestations in children
Twenty cases of Epstein-Barr virus (EBV)-associated lymphoproliferative syndrome (LPS), defined by the presence of EBV nuclear antigen and/or EBV DNA in tissues, were diagnosed in 1467 transplant recipients in Pittsburgh from 1981â1985. The frequency of occurrence in pediatric transplant recipients was 4% (10/ 253), while in adults it was 0.8% (10/1214) (P < .0005). The frequency of LPS in adults declined after 1983 coincidental with the introduction of cyclosporine monitoring. However there was no apparent decline of LPS in children. We describe these ten pediatric cases and one additional case of LPS in a child who received her transplant before 1981. The frequency of EBV infection in 92 pediatric liver recipients was 63%. Of these subjects, 49% were sero-negative and 77% of those acquired primary infection. Of 11 cases of pediatric EBV-associated LPS, 10 were in children who had primary infection shortly before or after transplantation. These results reinforce the impor-tance of primary EBV infection in producing LPS, which was previously shown in adults. Children are at greater risk because they are more likely to be seronegative for EBV and to acquire primary infection. Three clinical types of LPS were recognized in children. The first (5 cases) was a self-limited mononucleo-sislike syndrome. The second syndrome (4 cases) began similarly, but then progressed over the next two months to widespread lymphoproliferation in internal organs and death. The third type (2 cases) was an extranodal intestinal monoclonal B cell lymphoma, occurring late after primary infection. © 1988 by The Williams and Wilkins Co
Reproducing Hierarchies at the APSA Annual Meeting: Patterns of Panel Attendance by Gender, Race, and Ethnicity
Research on the political science profession has shown that homophilous research networksâthat is, those organized along the lines of gender and race/ethnicityâreproduce hierarchies. Research networks composed of white men experience the most prestige and lead to the most opportunities. This study documents homophilous networks in a setting where they likely are nurtured: academic conferences. Drawing data from the 2019 Annual Meeting of the American Political Science Association, we examine the correspondence between the gender and the racial/ethnic composition of section members, panelists, and audience members for four research sections: Political Methodology; Political Psychology; Race, Ethnicity, and Politics; and Women and Politics. We find that attendeesâ and panelistsâ gender and racial/ethnic identity largely mirror the dominant gender and racial/ethnic group in their section. These findings indicate that homophily manifests at academic conferences and that efforts to diversify research networks should consider who listens to whom in these settings
Influence of gravity on ocular lens position.
yesPurpose: To determine whether human ocular lens position is influenced by gravity.
Methods: Anterior chamber depth and lens thickness were determined with a Haag-Streit Lenstar LS900 for right eyes of participants in two age groups, with a young group of 13 participants aged 18 to 21 years (mean 21 years, SD 1 year) and an older group of 10 participants aged 50 to 63 years (58 years, 4 years). There were two sessions for each participant separated by at least 48 hours, with one session for the usual upright head position and one session for a downwards head position. In a session, testing was done for minimum accommodation followed by testing at maximum accommodation. A drop of 2% pilocarpine nitrate was instilled, and testing was repeated after 30 minutes under minimum and maximum accommodation conditions.
Results: Gravity, manipulated through head posture, affected anterior chamber depth for both young adult and older adult groups but mean effects were only small, ranging from 0.04 to 0.12mm, and for the older group required the instillation of an accommodation-stimulating drug. Gravity had a weakly significant effect on lens thickness for the young group without accommodation or a drug, but the effect was small at 0.04±0.06mm (mean±SD, p = 0.04).
Conclusion: There is a small but real effect of gravity on crystalline lens position, manifested as reduction in anterior chamber depth at high levels of accommodative effort with the head in a downwards position. This provides evidence of the ability of zonules to slacken during strong accommodation
Reversibility of lymphomas and lymphoproliferative lesions developing under cyclosporin-steroid therapy
Post-transplant lymphomas or other lymphoproliferative lesions, which were usually associated with Epstein-Barr virus infections, developed in 8, 4, 3, and 2 recipients, respectively, of cadaveric kidney, liver, heart, and heart-lung homografts. Reduction or discontinuance of immunosuppression caused regression of the lesions, often without subsequent rejection of the grafts. Chemotherapy and irradiation were not valuable. The findings may influence policies about treating other kinds of post-transplantation neoplasms
Epstein-Barr virus infections and DNA hybridization studies in posttransplantation lymphoma and lymphoproliferative lesions: The role of primary infection
Fourteen patients who developed B cell lymphomas or lymphoproliferative lesions after kidney, liver, heart, or heart-lung transplantation in Pittsburgh during 1981-1983 had active infection with Epstein-Barr virus (EBV)of the primary (six patients), reactivated (seven patients), or chronic (one patient) type. In transplant patients without tumors, the incidence of EBV infection was 30% (39 of 128). Only three of these patients had primary infections. Thus the frequency of active infection was significantly higher in patients with tumors, and patients with primary infections were at greater risk of developing tumors. Five of 13 tumors tested contained EBV nuclear antigen (EBNA) and nine of 11 contained EBV genomes detected by DNA-DNA hybridization with BamHI K, BamHI W, or EcoRI B cloned probes. All EBNA-positive tumors, except one, were also positive by hybridization. Only one tumor was negative for both EBNA and EBV DNA. These data suggest that EBV plays an etiologic role in the development of these lesions. © 1985 by The University of Chicago
Reduced tubulin tyrosination as an early marker of mercury toxicity in differentiating N2a cells
The aims of this work were to compare the effects of methyl mercury chloride and Thimerosal on neurite/process outgrowth and microtubule proteins in differentiating mouse N2a neuroblastoma and rat C6 glioma cells. Exposure for 4 h to sublethal concentrations of both compounds inhibited neurite outgrowth to a similar extent in both cells lines compared to controls. In the case of N2a cells, this inhibitory effect by both compounds was associated with a fall in the reactivity of western blots of cell extracts with monoclonal antibody T1A2, which recognises C-terminally tyrosinated α-tubulin. By contrast, reactivity with monoclonal antibody B512 (which recognises total α-tubulin) was unaffected at the same time point. These findings suggest that decreased tubulin tyrosination represents a neuron-specific early marker of mercury toxicity associated with impaired neurite outgrowth
Electrochromic orbit control for smart-dust devices
Recent advances in MEMS (micro electromechanical systems) technology are leading to spacecraft which are the shape and size of computer chips, so-called SpaceChips, or âsmart dust devicesâ. These devices can offer highly distributed sensing when used in future swarm applications. However, they currently lack a feasible strategy for active orbit control. This paper proposes an orbit control methodology for future SpaceChip devices which is based on exploiting the effects of solar radiation pressure using electrochromic coatings. The concept presented makes use of the high area-to-mass ratio of these devices, and consequently the large force exerted upon them by solar radiation pressure, to control their orbit evolution by altering their surface optical properties. The orbital evolution of Space Chips due to solar radiation pressure can be represented by a Hamiltonian system, allowing an analytic development of the control methodology. The motion in the orbital element phase space resembles that of a linear oscillator, which is used to formulate a switching control law. Additional perturbations and the effect of eclipses are accounted for by modifying the linearized equations of the secular change in orbital elements around an equilibrium point in the phase space of the problem. Finally, the effectiveness of the method is demonstrated in a test case scenario
Startup of the High-Intensity Ultracold Neutron Source at the Paul Scherrer Institute
Ultracold neutrons (UCN) can be stored in suitable bottles and observed for
several hundreds of seconds. Therefore UCN can be used to study in detail the
fundamental properties of the neutron. A new user facility providing ultracold
neutrons for fundamental physics research has been constructed at the Paul
Scherrer Institute, the PSI UCN source. Assembly of the facility finished in
December 2010 with the first production of ultracold neutrons. Operation
approval was received in June 2011. We give an overview of the source and the
status at startup.Comment: Proceedings of the International Conference on Exotic Atoms and
Related Topics - EXA2011 September 5-9, 2011 Austrian Academy of Sciences,
Theatersaal, Sonnenfelsgasse 19, 1010 Wien, Austria 6 pages, 3 figure
Report 14: Online community involvement in COVID-19 research & outbreak response: early insights from a UK perspective
The Patient Experience Research Centre (PERC) at Imperial College London is developing research to explore and understand peopleâs views about, experiences of and behavioural responses to the outbreak in the UK and elsewhere. To guide that effort and to help inform COVID-19 research and responses more broadly - for example in mathematical modelling and policy - PERC launched an online community involvement initiative that sought rapid, early insight from members of the public and aimed to establish a network for ongoing community engagement. Priority areas for COVID-19 research Vaccine development was considered the most urgent research priority for many respondents. Social studies exploring the publicâs experiences, risk perceptions and behaviours during this outbreak were necessary and important according to 95% of the respondents. Such research could: Improve the way the current outbreak response is planned and implemented; Improve the way information and guidance is provided to and understood by the public; Optimise the support provided to communities and vulnerable groups; and Improve future outbreak preparedness. Other recommended areas of research included: Understanding the role of the media in influencing how people react and respond; Furthering our basic understanding of the virus â how it spreads, who it affects the most and why, and whether people achieve and maintain immunity after being infected; Critiquing the UKâs response to the pandemic against that of other countries; and Ensuring lessons can be learnt from this outbreak to better equip us for future outbreaks, and public health emergencies in general. Key unmet needs amongst communities The main challenges described by respondents were ineffective communication, including access to information and information overload; and conflicting guidance and misinformation. Respondentsâ described feelings of concern, confusion and, in some cases, panic as a result of these communication and information challenges. Others shared their frustration that there was nowhere to post their concerns or questions. In addition, respondents expressed a need for more detailed and bespoke practical guidance about their risk and how best to prepare and protect themselves and their loved ones. Almost half (47%) wanted to hear about the latest research on the virus, and 45% wanted a dedicated internet portal where they could access the latest information and trusted guidance. Making information more accessible to different communities, including those who are not online and those who have English as a second language was also highlighted as a priority
STS-48 case study, 17-18 September 1991
Weather conditions are documented prior to and during the STS-48 attempted landing at the Shuttle Landing Facility at KSC on 18 Sep. 1991. Trends in meteorological data during 17 and 18 Sep. are examined along with their relationship to the overall weather pattern observed over the KSC region. The primary weather problems during the landing were the formation of showers within 10 nautical miles of the SLF and any ceiling less than 10,000 ft. The controlling factor of the weather was a high pressure ridge that was gradually weakening and moving off the northeast. As this occurred, the low level flow was switching from a easterly to a southeasterly direction. This change in wind direction was reflected by shower movement on the McGill radar and by trends in rawinsondes launched from the Cape. These rawinsondes also indicated that the boundary layers was becoming slightly more unstable several hours prior to the attempted landing which may have aided in the development of clouds and small isolated showers. Also, analyses of Doppler wind profiler and rawinsondes indicated a possible midlevel disturbance in the easterly flow pattern near 700 mb. This weak disturbance may have made the atmosphere a little more unstable early on 18 Sep. Finally, embedded within the southeasterly flow were several bands of low clouds. These clouds were rather difficult to see in unenhanced IR satellite imagery available to forecasters in real time. However, post analyses using several different enhancement curves, adapted from NESDIS, clearly reveals the presence of these clouds
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