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Recent evidence suggests that exercise plays a role in cognition and that the posterior cingulate cortex (PCC) can be divided into dorsal and ventral subregions based on distinct connectivity patterns.
To examine the effect of physical activity and division of the PCC on brain functional connectivity measures in subjective memory complainers (SMC) carrying the epsilon 4 allele of apolipoprotein E (APOE 4) allele.
Participants were 22 SMC carrying the APOE ɛ4 allele (ɛ4+; mean age 72.18 years) and 58 SMC non-carriers (ɛ4–; mean age 72.79 years). Connectivity of four dorsal and ventral seeds was examined. Relationships between PCC connectivity and physical activity measures were explored.
ɛ4+ individuals showed increased connectivity between the dorsal PCC and dorsolateral prefrontal cortex, and the ventral PCC and supplementary motor area (SMA). Greater levels of physical activity correlated with the magnitude of ventral PCC–SMA connectivity.
The results provide the first evidence that ɛ4+ individuals at increased risk of cognitive decline show distinct alterations in dorsal and ventral PCC functional connectivity.
We have found the central star of Abell 70 (PN G038.1–25.4, hereafter A 70) to be a binary consisting of a G8 IV-V secondary and a hot white dwarf. The secondary shows enhanced Ba II and Sr II features, firmly classifying it as a barium star. The nebula is found to have Type-I chemical abundances with helium and nitrogen enrichment, which combined with future abundance studies of the central star, will establish A 70 as a unique laboratory for studying s-process AGB nucleosynthesis.
We have combined 22 deep Chandra ACIS-I pointings to map over one square degree of the Carina complex. Our x-ray survey detects 69 of 70 known O-type stars and 61 of 130 known early B stars. The majority of single O stars display soft X-ray spectra and have a mean log LX/Lbol ≈ −7.5 suggesting shocks embedded in the O-star winds. Over OB stars show unusually high X-ray luminosities, high shock temperatures or time variability, not predicted for embedded wind shocks.
We have used continuous, high-precision, broadband visible photometry from the MOST satellite to trace wind structures in the WR component of CV Ser over more than a full orbit. Most of the small-scale light-curve variations are likely due to extinction by clumps along the line of sight to the O companion as it orbits and shines through varying columns of the WR wind. Parallel optical spectroscopy from the Mont Megantic Observatory is used to refine the orbital and wind-collision parameters, as well as to reveal line emission from clumps.
The Canadian MOST satellite is a unique platform for observations of bright transiting exoplanetary systems. Providing nearly continuous photometric observations for up to 4 weeks, MOST can produce important observational data to help us learn about the properties of exosolar planets. We review our current observations of HD 209458 and HD 189733 with implications for the albedo and our progress towards detecting reflected light from an exoplanet.
There is evidence to suggest that among young people with mild intellectual disability there are those whose cognitive difficulties may predict the subsequent manifestation of a schizophrenic phenotype. It is suggested that they may be detectable by simple means.
To gain adequate cooperation from educational services, parents and students so as to recruit a sufficiently large sample to test the above hypothesis, and to examine the hypothesis in the light of the findings.
The sample was screened with appropriate instruments, and groups hypothesised as being likely or not likely to have the phenotype were compared in terms of psychopathology and neuropsychology.
Simple screening methods detect a sample whose psychopathological and neuropsychological profile is consistent with an extended phenotype of schizophrenia.
Difficulties experienced by some young people with mild and borderline intellectual disability are associated with enhanced liability to schizophrenia. Clinical methods can both identify those with this extended phenotype and predict those in whom psychosis will occur.
The objective of this paper is to describe variations in the different models of out of hours general medical services and identify explanations for variation and the possible influence on patient satisfaction and service costs. A cross-sectional survey of all models of out of hours care was undertaken, including co-operatives, deputizing services, practice rotas and rural general practitioners doing their own cover. Fifteen sites were chosen representing 10 models of care, for more detailed case study; 65 semistructured interviews with key informants were conducted within the case study sites. A postal patient satisfaction questionnaire and an economic analysis were also carried out. Out of hours organizations have developed in response to a complex mix of the population served, geography, resources available and political expediency, leading to considerable structural heterogeneity, even within co-operatives. There was little evidence of formal integration with other services. Only the largest co-operatives showed any evidence of utilizing guidelines/protocols or of providing formal staff training. There were clear differences in the structure of out of hours care in urban and rural areas. Increasing the use of centralized call handling and triage will not address the needs of rural GPs, who would still be required to be available for work. Neither patient satisfaction nor costs varied bymodel of service provision. The English out of hours reviewhas outlined an integrated model of service provision with consistent standards within an accountability framework. It would appear that only the largest organizations will be in a position to address these standards and that they are likely to be inappropriate to the needs of GPs in rural areas.
Chondrosarcomas (CSA) of the temporal bone are rare primary malignant tumours that are slow growing, but locally aggressive. The management of CSAs involving the temporal bone is challenging and necessitates a multidisciplinary approach in a tertiary referral unit well practised in skull base surgery. Their management with particular reference to modes of presentation and treatment strategies has been reviewed here.
Primary cerebellopontine angle (CPA) cholesteatoma grows slowly and silently in the subarachnoidal spaces. The diagnosis is often late, when the lesion has reached large dimensions. Surgical removal is the only available therapy. Fifteen consecutive cases of CPA cholesteatoma managed at a tertiary otoneurosurgical referral unit between September 1985 and April 1999 were reviewed. The study population, consisting of seven males and eight females, had a mean age of 44 years of age (range 21–69) at the time of surgery. The clinical, audiological and radiological presentations were examined. The tumours were classified according to the Moffat classification of CPA cholesteatomas. In 67 per cent of cases the presenting symptom was related to the vestibulo-cochlear nerve. The average duration of symptoms was 23 months (ranging from one month–10 years). The hearing preservation approaches were utilized the most (11 cases), while the translabyrinthine approach alone, or in association with a middle fossa craniotomy, was performed in four cases. Tumour removal was total in 12 cases and subtotal in three cases. In cases undergoing hearing preservation surgery the mean pre-operative pure tone average (PTA) for the frequencies 0.5, 1, 2, and 3 kHz was 19.3 dB HL (SD 13.84) and the mean pre-operative speech discrimination score (SDS) was 89.8 per cent (SD 5.97). In 44.4 per cent of patients the hearing was preserved and the mean post-operative PTA was 20.29 dB HL (SD 15.84). In five patients post-operative complications occurred. No peri- or post-operative death occurred in this series, one patient developed a recurrence 15 years after the initial surgery.
We present the observational signature of a statistically significant number of very massive stars around the core of R136 and discuss the evidence for dynamical processes to be responsible for their apparent location. Alternative scenarios are discussed as well.
Recent studies have reported significant atrophy of the corpus callosum (CC) in Alzheimer's Disease (AD). However, it is currently unknown whether CC atrophy is associated with specific cortical volume changes in AD. Moreover, possible atrophy in extra-callosal commissures has not been examined to date. The purpose of the present study was to quantify atrophy in two cerebral commissures [the CC and the anterior commissure (AC)], to correlate this measure with cognitive status, and to relate commissural size to independent measures of temporal lobe volume in AD patients.
A sample of AD patients and of age- and education-matched normal control subjects (NCs) underwent MRI and a cognitive test battery including the Dementia Rating Scale and Mini Mental State examination. Mid-sagittal regional areas within CC and AC were measured along with superior, middle and inferior temporal lobes volumes.
Alzheimer's Disease patients had significantly smaller callosa than did NCs. The callosal regions most affected in AD included the midbody, isthmus and genu. The isthmus and midbody areas of the CC were positively correlated with cognitive performance and with superior temporal lobe volume in AD patients. The mid-sagittal area of the AC and the superior temporal volumes did not differ between AD patients and NCs.
The study demonstrated that the regional morphology of the CC correlates with current cognitive status and temporal lobe atrophy in AD. As well, the lack of difference for the AC suggests that commissural atrophy in AD is regionally specific.
Internal carotid artery aneurysms are a rare cause of pulsatile tinnitus and conductive hearing loss but should be borne in mind when there is a suspected diagnosis of glomus jugulare or high-riding jugular bulb. Most cases are congenital. We present a case of otorrhagia which was initially thought to be a glomus jugulare, the diagnosis of internal carotid artery aneurysm was made at angiography and treated by balloon embolization.
The aim of this study was the determination of the incidence of symptoms of audio-vestibular dysfunction and of abnormalities on audio-vestibular testing in patients found to have a unilateral meningioma of the cerebello-pontine angle (CPA). The case notes of 25 patients diagnosed with unilateral, sporadic and histologically proven CPA meningioma were retrospectively reviewed. The age range of this series was 31–71 years, with a mean age of 50 years. Two patients were male (eight per cent) and 23 were female (92 per cent). The mean length of history was 44.7 months. The distribution of tumour size was skewed toward larger tumours, with 15 cases (60 per cent) having tumours with a maximum diameter greater than 3.5 cm on imaging. Pure tone audiometry was normal in five cases (20 per cent), and no patients exhibited the high frequency sensorineural hearing loss that is characteristic of vestibular schwannoma. Speech audiometry was normal in 50 per cent of cases. Caloric testing was abnormal in 77 per cent of the 18 cases tested, whilst auditory brainstem responses (ABR) were abnormal in 100 per cent of the 18 cases who had sufficient hearing for this test to be possible. The presence of normal audiometry in patients with a proven CPA lesion indicates that, if in a protocol for investigation, asymmetry of hearing is mandatory then some pathology will be missed. Any suspicion of a CPA lesion warrants investigation even in the absence of hearing loss.
The investigation of choice for the identification of CPA lesions has become magnetic resonance imaging (MRI). If this technique is not available then this study indicates that ABR is a suitable and sensitive investigation. It should be borne in mind however that the data in this study has been derived from a series of predominantly large tumours, and the sensitivity of ABR to smaller CPA meningiomata may fall, as is the case for vestibular schwannoma.
In situ small angle neutron scattering (SANS) was used to characterize the formation of the random 3-dimensional porous structure created during the dealloying of a Ag0.7Au0.3 alloy under potential control. Using a model developed by N.F. Berk (Phys. Rev. Lett., 58 (1987) 2718) for the scattering properties of random porous media, we were able to characterize the average ligament width as a function of time during the dealloying process. We find that the coarsening of the average ligament width is strongly dependent upon the value of the applied potential. Our results represent the first in situ nanoscale characterization of the 3-dimensional formation of porosity in a dealloying system under potential control.
A case report of a thrombosed posterior-inferior cerebellar artery aneurysm is described. The tumour masqueraded as a vestibular schwannoma on imaging but the presenting featureswere unusual, the facial pain and weakness predominating despite well preserved hearing. This is an example of a rare cerebellopontine angle tumour and highlights the need for suspicion when lesions present atypically.
Vestibular schwannoma occurs both as a sporadic tumour and in the dominantly inherited familial cancer syndrome neurofibromatosis type 2 (NF2). The gene for NF2 has recently beenisolated on chromosome 22, and the demonstration of inactivating germline mutations in NF2 patients and NF2 associated tumours suggests that it acts as a tumour suppressor. The results of recent research in Cambridge suggest that somatic mutations of the NF2 tumour suppressor gene are a critical step in the pathogenesis of both familial and indeed non-familial unilateral sporadic vestibular schwannoma and that the mechanism of tumourigenesis complies with the ‘two-hit’ model. This paper represents a brief review of the current status of molecular biology in relation to vestibular schwannoma in particular and is discussed in relation to the molecular pathology of skull base tumours as a whole.
We present the case of a 40-year-old male Caucasian patient who developed surgical emphysema of the neck five weeks after surgery for exostoses of the external auditory canal. Imaging of the temporal bone demonstrated that the surgery had resulted in entry into the temporomandibular joint. A mechanism is proposed for this novel complication.
Twelve per cent of a series of 284 patients with vestibular schwannoma presented with sudden deafness. If sudden sensorineural hearing loss is present then it is very likely to be the main presenting symptom. The mean length of patients' history is eight months shorter in this group than in the non-sudden deafness group. Sixteen per cent of vestibular schwannoma patients without sudden deafness present with a 'dead' ear whereas 29.5 per cent of those presenting with sudden deafness have total hearing loss. There was no significant difference between the sudden deafness group and the 'all others' group with regard to tumour size, udiogram shape, caloric test, imbalance, and facial numbness. Although the numbers of patients with sudden deafness in this series were too small to reach significance, on the basis of the clinical correlation of vestibular schwannoma morphology it is possible to postulate that compression of the vasculature within the bony internal auditory canal by a laterally arising tumour may be the aetiological factor and may be more likely to occur than in more medially arising tumours.
Fifty-nine unusual cerebello-pontine angle tumours have been studied. These lesions represent 19.3 per cent or 1 in 5 of a series of 305 cerebello-pontine angle tumours of which the rest, 246 (80.7 per cent), were acoustic neuromas. An analysis of the relative incidence, histology and presenting clinical features has been carried out. The various radiographical features and imaging techniques used to diagnose these fascinating tumours have been described and also the otoneurosurgical procedures necessary to excise them.