3,464 research outputs found
Antigenic variation in the African trypanosome: molecular mechanisms and phenotypic complexity
Antigenic variation is an immune evasion strategy that has evolved in viral, bacterial and protistan pathogens. In the African trypanosome this involves stochastic switches in the composition of a variant surface glycoprotein (VSG) coat, using a massive archive of silent VSG genes to change the identity of the single VSG expressed at a time. VSG switching is driven primarily by recombination reactions that move silent VSGs into specialized expression sites, though transcription-based switching can also occur. Here we discuss what is being revealed about the machinery that underlies these switching mechanisms, including what parallels can be drawn with other pathogens. In addition, we discuss how such switching reactions act in a hierarchy and contribute to pathogen survival in the face of immune attack, including the establishment and maintenance of chronic infections, leading to host-host transmission
Activating Boxmind: an evaluation of a webâbased video lecture with synchronized activities
The aim of this study was to evaluate the use of synchronous computerâmediated communication activities in a video eâlecture. Previous research has reported that learning is facilitated when communication activities are added to a video lecture. Twelve postgraduate students participated in the study and they viewed a video eâlecture on the perspectiveâtaking theory of communication. The lecture consisted of a video image of the lecturer, an audio track, slides, the transcript and a number of communication activities. They were given a preâtest a week before the lecture and a postâtest a week after. They were also asked to rate the helpfulness of various aspects of the lecture. Studentsâ postâtest scores were statistically significantly higher than their preâtest scores. They found the audio track, transcript, slides and activities helpful. The most helpful aspects were the communication activities. The implications of these findings are discussed
Feeding Techniques To Increase Calf Growth In The First Two Months Of Life
End of project reportData from Cornell University and the University of Illinois in the USA suggested that average daily liveweight gains of 900 to 1000 g/calf/day could be achieved from birth to weaning provided the calf milk replacer (CMR) is formulated to meet the calfâs amino acid requirements for such a rate of gain. Their findings suggested a daily milk replacer DM allowance of 1250 to 1500 g/d with a crude protein content of 26 to 30%. A series of studies were undertaken, at ARINI with home born dairy calves and at Grange Beef Research Centre with purchased dairy calves, to determine the effect of increasing the daily milk replacer DM allowance and or increasing the crude protein content of the CMR on calf performance.The
main outcomes of these studies were
There was no growth or intake response in any of the studies to increasing the crude
protein content of the CMP from 23% to 28%.
Calf growth rates responded to increasing the dailymilk replacer allowance from 600
to 1200 g/day for both home bred and purchased calves. However, the effect was not
significant post-weaning in any of the studies.
In all of the studies (for both home reared and purchased calves) feeding a high level
of CMRdecreased concentrate DM intake. However, the calves concentrate intakes
were similar post-weaning.
The home bred calves with free access to the milk replacer feeders failed to consume
their 1200 g/day allowance. Calves offered 600 or 1200 g of CMR/day had average
consumption of 554 and 944 g/d, respectively, in the milk feeding period.
Feeding a high (1200 g/d) compared to a low level (600 g/d) CMRdiet for the first 56
days had no significant effect on carcass weight or carcass characteristics when
purchased male calves were slaughtered off an ad libitum concentrate diet after 388
days. The final carcass weights were 231 and 240 kg for the respective 600 and 1200
g/d CMR.
Reducing the fat content of the CMRfrom 18% to 12% did not have any effect on
concentrate intake or liveweight gain
A cluster randomised controlled trial of a pharmacist-led collaborative intervention to improve statin prescribing and attainment of cholesterol targets in primary care
Background:
Small trials with short term follow up suggest pharmacistsâ interventions targeted at healthcare professionals can improve prescribing. In comparison with clinical guidance, contemporary statin prescribing is sub-optimal and achievement of cholesterol targets falls short of accepted standards, for patients with atherosclerotic vascular disease who are at highest absolute risk and who stand to obtain greatest benefit. We hypothesised that a pharmacist-led complex intervention delivered to doctors and nurses in primary care, would improve statin prescribing and achievement of cholesterol targets for incident and prevalent patients with vascular disease, beyond one year.<p></p>
Methods:
We allocated general practices to a 12-month Statin Outreach Support (SOS) intervention or usual care. SOS was delivered by one of 11 pharmacists who had received additional training. SOS comprised academic detailing and practical support to identify patients with vascular disease who were not prescribed a statin at optimal dose or did not have cholesterol at target, followed by individualised recommendations for changes to management. The primary outcome was the proportion of patients achieving cholesterol targets. Secondary outcomes were: the proportion of patients prescribed simvastatin 40 mg with target cholesterol achieved; cholesterol levels; prescribing of simvastatin 40 mg; prescribing of any statin and the proportion of patients with cholesterol tested. Outcomes were assessed after an average of 1.7 years (range 1.4â2.2 years), and practice level simvastatin 40 mg prescribing was assessed after 10 years.<p></p>
Findings:
We randomised 31 practices (72 General Practitioners (GPs), 40 nurses). Prior to randomisation a subset of eligible patients were identified to characterise practices; 40% had cholesterol levels below the target threshold. Improvements in data collection procedures allowed identification of all eligible patients (n = 7586) at follow up. Patients in practices allocated to SOS were significantly more likely to have cholesterol at target (69.5% vs 63.5%; OR 1.11, CI 1.00â1.23; p = 0.043) as a result of improved simvastatin prescribing. Subgroup analysis showed the primary outcome was achieved by prevalent but not incident patients. Statistically significant improvements occurred in all secondary outcomes for prevalent patients and all but one secondary outcome (the proportion of patients with cholesterol tested) for incident patients. SOS practices prescribed more simvastatin 40 mg than usual care practices, up to 10 years later.<p></p>
Interpretation:
Through a combination of educational and organisational support, a general practice based pharmacist led collaborative intervention can improve statin prescribing and achievement of cholesterol targets in a high-risk primary care based population
Immune Protection Against Chlamydia trachomatis in Females
Despite significant advances in our understanding of the biology and antigenic structure of
Chlamydia trachomatis, and the epidemiology and clinical spectrum of chlamydial disease, the magnitude of
morbidity from human chlamydial infections remains an important public health concern. Control
of chlamydial disease will likely depend on a multidisciplinary approach, including the development
of immunoprophylactic or immunotherapeutic strategies. Reasonable progress has been made in
understanding specific immune mechanisms that contribute to host immunity in experimental models
of chlamydial infection. However, studies of human immunity have not been so successful. This
is particularly evident in that studies to address the development and role of mucosal immune
responses to urogenital chlamydial infections have not been forthcoming. The following review is
a brief summary of our current knowledge of protective immunity to chlamydial urogenital infections
of females. It is not meant to be exhaustive, but instead to touch upon aspects of protective immunity
that have been described in both human and experimental animal models of chlamydial
infection
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