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Executive and mnemonic impairments have been well documented in the high-risk states for development of psychosis and have been pinpointed as a possible core neuropsychological dysfunction. However, their neurofunctional correlates are still not clear.
fMRI was used in 17 patients at risk for developing psychosis (ARMS, “at risk mental state”), 10 patients with a first episode of psychosis (FEP) and 15 age-matched healthy comparison subjects to examine neural responses to increasing difficulty of mnemonic engagement in an object–location paired associate memory task. Groups were matched in terms of age, IQ, gender, and psychopathology ratings. Accuracy and reaction time were recorded during the scan.
As the mnemonic load increased, response latency increased and response accuracy decreased in an approximately linear fashion. No main effect for group was observed. However, a trend towards decreased accuracy in FEP subjects, as compared with controls, was evident. As the task difficulty increased, increased brain activity was observed in the medial frontal cortex and in the medial posterior parietal cortex. Between-groups differences in activation were observed in a cluster spanning the MFG, SFG and SMA and in the right precuneus. However, these neurofunctional abnormalities were more evident in the most demanding level of the task than in the easy level, with the ARMS groups showing less activation than controls and higher activation than FEP.
Abnormal neural activity in medial frontal cortex and posterior parietal cortex during paired associate learning task may represent a neurofunctional substrates of vulnerability to psychosis.
Mood instability is common, and an important feature of several psychiatric
disorders. We discuss the definition and measurement of mood instability,
and review its prevalence, characteristics, neurobiological correlates and
clinical implications. We suggest that mood instability has underappreciated
transdiagnostic potential as an investigational and therapeutic target.
The majority of species are under predatory risk in their natural habitat and targeted by
predators as part of the food web. During the evolution of ecosystems, manifold mechanisms
have emerged to avoid predation. So called secondary defences, which are used after a
predator has initiated prey-catching behaviour, commonly involve the expression of toxins
or deterrent substances which are not observable by the predator. Hence, the possession of
such secondary defence in many prey species comes with a specific signal of that defence
(aposematism). This paper builds on the ideas of existing models of such signalling
behaviour, using a model of co-evolution and generalisation of aversive information and
introduces a new methodology of numerical analysis for finite populations. This new
methodology significantly improves the accessibility of previous models.
In finite populations, investigating the co-evolution of defence and signalling requires
an understanding of natural selection as well as an assessment of the effects of drift as
an additional force acting on stability. The new methodology is able to reproduce the
predicted solutions of preceding models and finds additional solutions involving negative
correlation between signal strength and the extent of secondary defence. In addition,
genetic drift extends the range of stable aposematic solutions through the introduction of
a new pseudo-stability and gives new insights into the diversification of aposematic
Evidence from the literature supports the safe use of very-low-energy diets (VLED) for up to 3 months in supervised conditions for patients who fail to meet a target weight loss using a standard low-fat, reduced-energy approach. There is, however, a need for longer-term outcomes on obesity and associated morbidities following a VLED. The present systematic review aims to investigate longer-term outcomes from studies using VLED, with a minimum duration of 12 months, published between January 2000 and December 2010. Studies conducted in both children and adults, with a mean/median BMI of ≥ 28 kg/m2 were included. PubMed, MEDLINE, Web of Science and Science Direct were searched. Reference lists of studies and reviews were manually searched. Weight loss or prevention of weight gain and morbidities were the main outcomes assessed. A total of thirty-two out of 894 articles met the inclusion criteria. The duration of the studies ranged from 12 months to 5 years. Periods of VLED ranged from 25 d to 9 months. Several studies incorporated aspects of behaviour therapy, exercise, low-fat diets, low-carbohydrate diets or medication. Current evidence demonstrates significant weight loss and improvements in blood pressure, waist circumference and lipid profile in the longer term following a VLED. Interpretation of the results, however, was restricted and conclusions with which to guide best practice are limited due to heterogeneity between the studies. The present review clearly identifies the need for more evidence and standardised studies to assess the longer-term benefits from weight loss achieved using VLED.
Impaired spatial working memory (SWM) is a robust feature of schizophrenia and has been linked to the risk of developing psychosis in people with an at-risk mental state (ARMS). We used functional magnetic resonance imaging (fMRI) to examine the neural substrate of SWM in the ARMS and in patients who had just developed schizophrenia.
fMRI was used to study 17 patients with an ARMS, 10 patients with a first episode of psychosis and 15 age-matched healthy comparison subjects. The blood oxygen level-dependent (BOLD) response was measured while subjects performed an object–location paired-associate memory task, with experimental manipulation of mnemonic load.
In all groups, increasing mnemonic load was associated with activation in the medial frontal and medial posterior parietal cortex. Significant between-group differences in activation were evident in a cluster spanning the medial frontal cortex and right precuneus, with the ARMS groups showing less activation than controls but greater activation than first-episode psychosis (FEP) patients. These group differences were more evident at the most demanding levels of the task than at the easy level. In all groups, task performance improved with repetition of the conditions. However, there was a significant group difference in the response of the right precuneus across repeated trials, with an attenuation of activation in controls but increased activation in FEP and little change in the ARMS.
Abnormal neural activity in the medial frontal cortex and posterior parietal cortex during an SWM task may be a neural correlate of increased vulnerability to psychosis.
A description is given of the topography, type of farming carried out, and the living conditions of the agricultural community of a district in South Wales where a survey was made of the infection rate of rats with Leptospira icterohaemorrhagiae.
Leptospires were seen in stained sections of the kidneys of eighty-two of the 357 rats examined (23%). With a single exception, all the infected rats were adult, but no difference in sex-incidence was found.
Weil's disease occurs in this area, but no cases in man or cattle had been reported from this particular locality. Blood samples taken from six persons living on two heavily infested farms contained no anti-leptospiral agglutinins.
Despite the increasing development of early intervention services for psychosis, little is known about their cost-effectiveness. We assessed the cost-effectiveness of Outreach and Support in South London (OASIS), a service for people with an at-risk mental state (ARMS) for psychosis.
The costs of OASIS compared to care as usual (CAU) were entered in a decision model and examined for 12- and 24-month periods, using the duration of untreated psychosis (DUP) and rate of transition to psychosis as key parameters. The costs were calculated on the basis of services used following referral and the impact on employment. Sensitivity analysis was used to test the robustness of all the assumptions made in the model.
Over the initial 12 months from presentation, the costs of the OASIS intervention were £1872 higher than CAU. However, after 24 months they were £961 less than CAU.
This model suggests that services that permit early detection of people at high risk of psychosis may be cost saving.
Cognitive models propose that faulty appraisal of anomalous experiences
is critical in developing psychosis, particularly delusions. A data
gathering bias may be fundamental to abnormal appraisal
To examine whether there is a data gathering bias in people at high risk
of developing psychosis
Individuals with an at-risk mental state (n=35) were
compared with a matched group of healthy volunteers
(n=23). Participants were tested using a modified
version of the ‘beads’ reasoning task with different levels of task
When task demands were high, the at-risk group made judgements on the
basis of less information than the control group (P <
0.05). Within both groups, jumping to conclusions was directly correlated
with the severity of abnormal beliefs and intolerance of uncertainty
(P<0.05). In the at-risk group it was also
associated with impaired working memory (P<0.05),
whereas in the control group poor working memory was associated with a
more conservative response style (P<0.05)
People with an at-risk mental state display a jumping to conclusions
reasoning style, associated with impaired working memory and intolerance
of uncertainty. This may underlie a tendency to develop abnormal beliefs
and a vulnerability to psychosis
Off-axis electron holography is used to measure electrostatic
potential profiles across a silicon p-n junction,
which has been prepared for examination in the transmission electron
microscope (TEM) in two different specimen geometries using focused ion
beam (FIB) milling. Results are obtained both from a conventional
unbiased FIB-milled sample and using a novel sample geometry that
allows a reverse bias to be applied to an FIB-milled sample in
situ in the TEM. Computer simulations are fitted to the results to
assess the effect of TEM specimen preparation on the charge density and
the electrostatic potential in the thin sample.
We examined three species of diminutive Porphyra,Porphyra suborbiculata Kjellman from the North Pacific, Porphyra lilliputiana W. A. Nelson, G. A. Knight et M. W. Hawkes from the South Pacific, and Porphyra carolinensis Coll et J. Cox from the western North Atlantic. These taxa were compared in terms of morphology, habitat data and sequence haplotypes of nuclear small subunit rDNA (SSU) and internal transcribed spacers of the nuclear rDNA cistron (ITS). These three species have similar morphologies and growth habits, and share very similar type descriptions and habitat records. Haplotype variation was found within the 11 samples of P. lilliputiana we examined and within P. suborbiculata samples from two locations, but the single P. carolinensis haplotype (from collections from two separate locations) was identical to one found in several widespread P. lilliputiana samples. Unrooted phylogenetic trees based on sequence data do not support any of the three species as being a monophyletic group. We conclude that these three taxa represent a single species with the oldest name P. suborbiculata having nomenclatural priority. It is likely that P. suborbiculata has recently been introduced to the western Atlantic from the Pacific region.
A wide range of measures have been employed in an attempt to determine social structure in groups of animals and different analyses of social behaviour may result in the construction of different hierarchies (Tomback et al. 1989). In order to investigate social aspects of welfare in group-housed sows it is important to establish a meaningful measure of group dynamics. We therefore wished to establish whether different measures of social status resulted in the construction of similar hierarchies in dry-sows housed in indoor or outdoor group-housing systems.
Twenty pregnant sows sharing a double-entry back-out Pig Code feeder with a similar group of 20 were observed over six 24-h feed cycles by a combination of direct observation and video recording. The group had access to an area of 47 m2. Sows were fed once a day on a pelleted diet and water was continually available. Feeding order was relatively constant from day to day, and was positively correlated with parity. A social hierarchy based on displacements and attacks within pairs of sows was found to be basically linear, with the exception of six reversals of dominance. Social hierarchy was positively correlated with feeding order overall, but this was not the case for the latter half of the feeding order. This was partly due to disruption of feeder use by non-feeding visits made by early-feeding dominant sows. Overall the results showed that older sows with more experience of the feeder in two or three previous parities were higher in the feeding order and social hierarchy than younger sows, and may exclude them from the feeder by repeated non-feeding visits.
Five species of Muscidae were found to be commonly associated with dairy heifers in three areas in southern England. The biting flies Haematobosca stimulans (Mg.) and Stomoxys calcitrans (L.) were relatively rare and fed from the back, flanks and legs. The horn fly, Haematobia irritans (L.), was present in highest numbers; it rested on the back and fed on the legs, belly and occasionally on the teats. Musca autumnalis Deg. was found mainly on the head and had a restricted season. Hydrotaea irritans (Fall.) had a marked diurnal variation in activity, being most abundant in the morning and evening. It was found on the head but predominantly on the belly and teats. When judged by its site preference on cattle, it is the fly most likely to be involved in the transmission of summer mastitis.
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