390 research outputs found
Longevity of an immunocontraceptive vaccine effect on fecundity in rats
Increases in human-wildlife conflicts alongside cultural shifts against lethal control methods are driving the need for alternative wildlife management tools such as fertility control. Contraceptive formulations suitable for oral delivery would permit broader remote application in wildlife species.
This study evaluated the contraceptive effect and immune response to two novel injectable immunocontraceptive formulations targeting the Gonadotropin Releasing Hormone (GnRH): MAF-IMX294 and MAF-IMX294P conjugates, both identified as having potential as oral contraceptives. The study also explored whether in multiparous species immunocontraceptives may either totally prevent reproduction or also affect litter size.
Female rats, chosen as a model species, were given three doses of either MAF-IMX294 or MAFIMX294P to compare anti-GnRH immune response and reproductive output up to 310 days posttreatment.
Both formulations induced anti-GnRH antibody titres in 100% of rats and significantly impaired fertility compared to control animals. Following treatment with MAF-IMX294 and MAF-IMX294P 0 of 9 and 1 of 10 females respectively produced litters following the first mating challenge 45 days posttreatment, compared to 9 of 9 control animals.
Across the whole 310 day study period 7 of 9 females from the MAF-IMX294 group and 10 of 10 females in the MAF-IMX294P group became fertile, producing at least one litter throughout six mating challenges.
No significant differences were found between the two formulations in antibody titre response or duration of contraceptive effect, with an average time to first pregnancy of 166 days for MAFIMX294 and 177 days for MAF-IMX294P for all females that became fertile.
Following treatment with MAF-IMX294 and MAF-IMX294P the first litter produced post-infertility in treated females was significantly smaller than in control animals. This indicates treatment with immunocontraceptives may induce an overall suppression of fecundity extending past an initial infertility effect. This increases the potential long-term impact of these immunocontraceptives in multiparous species such as commensal rodents
Photon production in relativistic nuclear collisions at SPS and RHIC energies
Chiral Lagrangians are used to compute the production rate of photons from
the hadronic phase of relativistic nuclear collisions. Special attention is
paid to the role of the pseudovector a_1 meson. Calculations that include
reactions with strange mesons, hadronic form factors and vector spectral
densities consistent with dilepton production, as well as the emission from a
quark-gluon plasma and primordial nucleon-nucleon collisions, reproduce the
photon spectra measured at the Super Proton Synchrotron (SPS). Predictions for
the Relativistic Heavy Ion Collider (RHIC) are made.Comment: Work presented at the 26th annual Montreal-Rochester-Syracuse-Toronto
conference (MRST 2004) on high energy physics, Montreal, QC, Canada, 12-14
May 2004. 8 pages, 3 figure
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The need for a marker predicting benefit following cardiovascular disease risk reduction treatment
Developing a robust method to study characteristics of vascular flow using ultrasound may be useful to assess endothelial function and vasodilatation. There are four stages in this proposal. 1.The first stage is to standardise and validate the methodology to enable computational risk flow data and other flow characteristics to be used clinically. (Current Study). Further development of fluid modelling methods will enable particulate haemodynamics to be investigated, and incorporate detailed endothelial structure together with cellular pathways. 2. This should be followed up by studies in different patient groups investigating the association between the derived values and estimated risk (using other methods such as Framingham risk score). 3. Then, associated with underlying cardiovascular risk, prospective studies would be made to establish whether computational flow dynamic data can predict outcome. If successful it could prove to be a very useful marker of benefit following treatment in a clinical setting
The Quenching of the Axial Coupling in Nuclear and Neutron-Star Matter
Using a chirally invariant effective Lagrangian, we calculate the density and
isospin dependences of the in-medium axial coupling, , in spatially
uniform matter present in core collapse supernovae and neutron stars. The
quenching of with density in matter with different proton fractions is
found to be similar. However, our results suggest that the quenching of the
nucleon's in matter with hyperons is likely to be significantly greater
than in matter with nucleons only.Comment: 4 pages revtex, 2 eps figure
Unveiling faculty conceptions of academic risk taking:a phenomenographic study
Among recent developments in the field of higher education is the emergence of New Public Management and of what has been labelled as ârisk universityâ. The aim of this paper is to redress the lack of discussion over the role that risk taking plays in academic practice by exploring what faculty understand academic risk taking to be and how they enact this understanding in their tasks. Drawing on a phenomenographic perspective and semi-structured interviews with 20 faculty members from a high-profile UK university, we find that academic risk taking is experienced in four qualitatively different ways. Our results suggest that although academics engage in relatively similar endeavours, they exhibit various approaches to these endeavours due to their different conceptions of what constitutes academic risk taking. These findings have implications for the literature on identity construction and the debate over how the greater accountability of academic activity is affectively experienced
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A pilot study to assess peak systolic velocity as a possible marker of atherosclerotic burden using ultrasound
Effect of vaccination with a novel GnRH-based immunocontraceptive on immune responses and fertility in rats
1. As human-wildlife conflicts increase worldwide, novel methods are required for mitigating these conflicts. Fertility control, based on immunocontraceptives, has emerged as an alternative option to lethal methods for managing wildlife.
2. Immunocontraceptives are vaccines that generate an immune response to key components of an animal\u27s reproductive system. Some of these vaccines target the gonadotropin-releasing hormone (GnRH) and have been used successfully as contraceptives for many wildlife species. However, the need to capture animals for treatment limits the field applications of injectable vaccines. The availability of orally delivered immunocontraceptives would increase the breadth of applications of fertility control for wildlife management.
3. This study explored a new approach to developing an oral immunocontraceptive, exploiting the bioadhesive and immunologically active properties of killed Mycobacterium avium cell wall fragments (MAF). The MAF was conjugated to a GnRH recombinant protein called IMX294, used as a GnRH-specific immunogen.
4. An initial trial using the MAF-IMX294 conjugate provided the first evidence that an orally delivered immunocontraceptive vaccine could generate anti-GnRH antibody titres in laboratory rats.
5. Increasing the dose and frequency of vaccine administered to rats, in a second trial, enhanced the immune response, eliciting titres that reduced the proportion of females giving birth. This provided the first evidence of the contraceptive effect of an oral anti-GnRH vaccine.
6. Future work is required to further increase the immunogenic effect of the oral vaccine and to establish a dosing schedule that is effective for practical field applications
Bag Formation in Quantum Hall Ferromagnets
Charged skyrmions or spin-textures in the quantum Hall ferromagnet at filling
factor nu=1 are reinvestigated using the Hartree-Fock method in the lowest
Landau level approximation. It is shown that the single Slater determinant with
the minimum energy in the unit charge sector is always of the hedgehog form. It
is observed that the magnetization vector's length deviates locally from unity,
i.e. a bag is formed which accommodates the excess charge. In terms of a
gradient expansion for extended spin-textures a novel O(3) type of effective
action is presented, which takes bag formation into account.Comment: 13 pages, 3 figure
On different lagrangian formalisms for vector resonances within chiral perturbation theory
We study the relation of vector Proca field formalism and antisymmetric
tensor field formalism for spin-one resonances in the context of the large N_C
inspired chiral resonance Lagrangian systematically up to the order O(p6) and
give a transparent prescription for the transition from vector to antisymmetric
tensor Lagrangian and vice versa. We also discuss the possibility to describe
the spin-one resonances using an alternative "mixed" first order formalism,
which includes both types of fields simultaneously, and compare this one with
the former two. We also briefly comment on the compatibility of the above
lagrangian formalisms with the high-energy constraints for concrete VVP
correlator.Comment: 34 pages, 3 figure
Properties of vector mesons at finite temperature -effective lagrangian approach-
The properties of -mesons at finite temperature () are examined with
an effective chiral lagrangian in which vector and axial-vector mesons are
included as massive Yang-Mills fields of the chiral symmetry. It is shown that,
at order, the effective mass is not changed but only the mixing effect in
vector and axial-vector correlator appears.Comment: 13 pages (REVTeX), two figures
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