850 research outputs found
Repetitive proteins from the flagellar cytoskeleton of African trypanosomes are diagnostically useful antigens
Trypanosome infection of mammalian hosts leads, within days, to a strong early response against a small, distinct number of parasite proteins. One of these proteins is the variable surface glycoprotein (VSG). Most of the others are apparently non-variable, intracellular trypanosome proteins. Two of these antigens I2 and I17 are now characterized at the molecular level. Both exhibit a highly repetitive amino acid sequence organization, but they show no sequence similarity either to each other or to any other proteins known to date. Preliminary serological analyses indicate that both allow the early, sensitive and specific detection of infections with different species of trypanosomatids, making them interesting candidates for the development of diagnostic tools for trypanosomiasis detectio
Repetitive proteins from the flagellar cytoskeleton of African trypanosomes are diagnostically useful antigens
Trypanosome infection of mammalian hosts leads, within days, to a strong early response against a small, distinct number of parasite proteins. One of these proteins is the variable surface glycoprotein (VSG). Most of the others are apparently non-variable, intracellular trypanosome proteins. Two of these antigens I2 and I17 are now characterized at the molecular level. Both exhibit a highly repetitive amino acid sequence organization, but they show no sequence similarity either to each other or to any other proteins known to date. Preliminary serological analyses indicate that both allow the early, sensitive and specific detection of infections with different species of trypanosomatids, making them interesting candidates for the development of diagnostic tools for trypanosomiasis detection
Identification and characterization of two repetitive non-variable antigens from African trypanosomes which are recognized early during infection
The present paper describes two repetitive proteins representing common antigens of African trypanosomes which are non-variant and which are recognized early in infection by the host immune system. These antigens were identified by their ability to immunoreact with bovine serum taken during the early phase of a cyclic trypanosomal infection. Screening of a cDNA library from T. b. gambiense with such early infection serum identified a protein which contains a repetitive motif consisting of 68 amino acid repeat units (GM6). Immunofluorescence and immunogold electron microscopy revealed that GM6 is located on fibres which connect the microtubules of the membrane skeleton with the flagellum. A second repetitive antigen detected by this serum is MARP1 (microtubule-associated repetitive protein 1), a protein previously characterized in this laboratory as a high-molecular weight component of the membrane skeleton, which consists of more than 50 tandemly repeated, near-identical 38 amino acid repeat units. Beta-galactosidase fusion products of both proteins demonstrated a strong immunoreactivity with sera from T. b. brucei and T. congolense-infected cattle. The result from this preliminary immunological evaluation indicates a high immunodiagnostic sensititivy (90%) of the two recombinant antigens which make them interesting candidates for immunodiagnosis of trypanosomiasis in cattl
Identification and characterization of two repetitive non-variable antigens from African trypanosomes which are recognized early during infection
The present paper describes two repetitive proteins representing common antigens of African trypanosomes which are non-variant and which are recognized early in infection by the host immune system. These antigens were identified by their ability to immunoreact with bovine serum taken during the early phase of a cyclic trypanosomal infection. Screening of a cDNA library from T. b. gambiense with such early infection serum identified a protein which contains a repetitive motif consisting of 68 amino acid repeat units (GM6). Immunofluorescence and immunogold electron microscopy revealed that GM6 is located on fibres which connect the microtubules of the membrane skeleton with the flagellum. A second repetitive antigen detected by this serum is MARP1 (microtubule-associated repetitive protein 1), a protein previously characterized in this laboratory as a high-molecular weight component of the membrane skeleton, which consists of more than 50 tandemly repeated, near-identical 38 amino acid repeat units. Beta-galactosidase fusion products of both proteins demonstrated a strong immunoreactivity with sera from T. b. brucei and T. congolense-infected cattle. The result from this preliminary immunological evaluation indicates a high immunodiagnostic sensititivy (90%) of the two recombinant antigens which make them interesting candidates for immunodiagnosis of trypanosomiasis in cattle
Cyclotron resonant scattering feature simulations. I. Thermally averaged cyclotron scattering cross sections, mean free photon-path tables, and electron momentum sampling
Electron cyclotron resonant scattering features (CRSFs) are observed as
absorption-like lines in the spectra of X-ray pulsars. A significant fraction
of the computing time for Monte Carlo simulations of these quantum mechanical
features is spent on the calculation of the mean free path for each individual
photon before scattering, since it involves a complex numerical integration
over the scattering cross section and the (thermal) velocity distribution of
the scattering electrons.
We aim to numerically calculate interpolation tables which can be used in
CRSF simulations to sample the mean free path of the scattering photon and the
momentum of the scattering electron. The tables also contain all the
information required for sampling the scattering electron's final spin.
The tables were calculated using an adaptive Simpson integration scheme. The
energy and angle grids were refined until a prescribed accuracy is reached. The
tables are used by our simulation code to produce artificial CRSF spectra. The
electron momenta sampled during these simulations were analyzed and justified
using theoretically determined boundaries.
We present a complete set of tables suited for mean free path calculations of
Monte Carlo simulations of the cyclotron scattering process for conditions
expected in typical X-ray pulsar accretion columns (0.01<B/B_{crit}<=0.12,
where B_{crit}=4.413x10^{13} G and 3keV<=kT<15keV). The sampling of the tables
is chosen such that the results have an estimated relative error of at most
1/15 for all points in the grid. The tables are available online at
http://www.sternwarte.uni-erlangen.de/research/cyclo.Comment: A&A, in pres
Negotiating sexuality and masculinity in school sport: An autoethnography
This autoethnography explores challenging and ethically sensitive issues around sexual orientation, sexual identity and masculinity in the context of school sport. Through storytelling, I aim to show how sometimes ambiguous encounters with heterosexism, homophobia and hegemonic masculinity through sport problematise identity development for young same-sex attracted males. By foregrounding personal embodied experience, I respond to an absence of stories of gay and bisexual experiences among males in physical education and school sport, in an effort to reduce a continuing sense of Otherness and difference regarding same-sex attracted males. I rely on the story itself to express the embodied forms of knowing that inhabit the experiences I describe, and resist a finalising interpretation of the story. Instead, I offer personal reflections on particular theoretical and methodological issues which relate to both the form and content of the story
Spectral and Timing Analysis of the accretion-powered pulsar 4U 1626-67 observed with Suzaku and NuSTAR
We present an analysis of the spectral shape and pulse profile of the
accretion-powered pulsar 4U 1626-67 observed with Suzaku and NuSTAR during a
spin-up state. The pulsar, which experienced a torque reversal to spin-up in
2008, has a spin period of 7.7 s. Comparing the phase-averaged spectra obtained
with Suzaku in 2010 and with NuSTAR in 2015, we find that the spectral shape
changed between the two observations: the 3-10 keV flux increased by 5% while
the 30-60 keV flux decreased significantly by 35%. Phase-averaged and
phase-resolved spectral analysis shows that the continuum spectrum observed by
NuSTAR is well described by an empirical NPEX continuum with an added broad
Gaussian emission component around the spectral peak at 20 keV. Taken together
with the observed Pdot value obtained from Fermi/GBM, we conclude that the
spectral change between the Suzaku and NuSTAR observations was likely caused by
an increase of the accretion rate. We also report the possible detection of
asymmetry in the profile of the fundamental cyclotron line. Furthermore, we
present a study of the energy-resolved pulse profiles using a new relativistic
ray tracing code, where we perform a simultaneous fit to the pulse profiles
assuming a two-column geometry with a mixed pencil- and fan-beam emission
pattern. The resulting pulse profile decompositions enable us to obtain
geometrical parameters of accretion columns (inclination, azimuthal and polar
angles) and a fiducial set of beam patterns. This information is important to
validate the theoretical predictions from radiation transfer in a strong
magnetic field.Comment: 19 pages, 14 figures, Accepted for publication in ApJ on May 5, 201
Be-Phenomenon in Neutron Star X-ray Binaries
In this work we provide a brief insight into two aspects of Be/X-ray binaries, which are probably involved in production of X-ray outbursts: the evolution of the Be star disk, in particular of its size, and the binary geometry which drives gravitational interaction. Simultaneous X-ray and optical data will aid our investigation of the evolution of Be stars in binaries and the X-ray outburst mechanism
TRIPS implementation and secondary pharmaceutical patenting in Brazil and India
This article compares national approaches toward secondary pharmaceutical patents. Because secondary patents can extend periods of exclusivity and delay generic competition, they can raise prices and reduce access to medicines. Little is known about what measures countries have enacted policies to address applications for secondary pharmaceutical patents, how they function, and whether, in practice, these measures limit secondary patents. We analyze the cases of India and Brazil. We assemble data on pharmaceutical patent applications filed in the two countries, code each application to identify which constitute secondary applications, and examine outcomes for each application in both countries. The data indicate that Brazil is less likely to grant applications than India, but in both countries the measures designed to limit secondary patents are having little direct effect. This suggests, on the one hand, that critics of these policies, such as the transnational pharmaceutical sector and foreign governments, may be more worried than they should be. On the other hand, champions of the policies, such as NGOs and international organizations, may have cause for concern that laws on the books are not having the expected impact on patent outcomes in practice. Our findings also suggest that, at the drug level, the effects of countriesâ approaches toward secondary patents need to be understood in the context of their broader approaches toward TRIPS implementation, including when and how they introduced pharmaceutical patents in the 1990s and 2000s
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