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The ventral tegmental area (VTA) is a heterogeneous midbrain structure, containing neurons and astrocytes, that coordinates behaviors by integrating activity from numerous afferents. Within neuron-astrocyte networks, astrocytes control signals from distinct afferents in a circuit-specific manner, but whether this capacity scales up to drive motivated behavior has been undetermined. Using genetic and optical dissection strategies we report that VTA astrocytes tune glutamatergic signaling selectively on local inhibitory neurons to drive a functional circuit for learned avoidance. In this circuit, astrocytes facilitate excitation of VTA GABA neurons to increase inhibition of dopamine neurons, eliciting real-time and learned avoidance behavior that is sufficient to impede expression of preference for reward. Loss of one glutamate transporter (GLT-1) from VTA astrocytes selectively blocks these avoidance behaviors and spares preference for reward. Thus, VTA astrocytes selectively regulate excitation of local GABA neurons to drive a distinct avoidance circuit that opposes approach behavior.

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We compare the near edge structure (NES) of cubic boron nitride (cBN) measured using both electron energy loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) with that calculated using three commonly used theoretical approaches. The boron and nitrogen K-edges collected using EELS and XAS from cBN powder were found to be nearly identical. These experimental edges were compared to calculations obtained using an all-electron density functional theory code (WIEN2k), a pseudopotential density functional theory code (CASTEP) and a multiple scattering code (FEFF). All three codes were found to reproduce the major features in the NES for both ionisation edges when a core-hole was included in the calculations. A partial core hole (1/2 of a 1s electron) was found to be essential for correctly reproducing features near the edge threshold in the nitrogen K-edge and to correctly obtain the positions of all main peaks. CASTEP and WIEN2k were found to give almost identical results. These codes were also found to produce NES which most closely matched experiment based on χ² calculations used to qualitatively compare theory and experiment. This work demonstrated that a combined experimental and theoretical approach to the study of NES is a powerful way of investigating bonding and electronic structure in boron nitride and related materials.

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OBJECTIVES: To compare percutaneous transluminal angioplsty (PTA) against exercise training in the treatment of stable claudication. DESIGN: Prospective, randomised trial. MATERIALS: Fifty-six patients with unilateral, stable, lower limb claudication assessed prior to randomisation, at 3 monthly intervals for 15 months, and at approximately 6 years follow-up. Thirty-seven patients were available for long term review. OUTCOME MEASURES: Ankle/brachial pressure index (ABPI), treadmill claudication and maximum walking distances, percentage fall in ankle systolic pressure after exercise. RESULTS: Significant increases were seen in ABPI in the patients treated with PTA at all assessment to 15 months. However in terms of improved walking performance, the most significant changes in claudication and maximum walking distance were seen in the exercise training group. At long term follow-up, there was no significant difference between the groups. Subgroup analysis by angiographic site of disease showed greater functional improvement in those patients with disease confined to the superficial femoral artery treated by exercise training. The overall prognosis for the whole group of patients was benign, with only two (4%) undergoing amputation. CONCLUSIONS: Exercise training confers a greater improvement in claudication and maximum walking distance than PTA, especially in patients with disease confined to the superficial femoral artery.

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BACKGROUND: Erroneous perceptions of peer weight norms may be important risk factors for being underweight and overweight. This study assessed misperceptions of peer weight norms and their association with being overweight or underweight among UK youth. METHODS: Anonymous surveys were conducted among students (n=2104) attending schools in a Greater London borough in Fall 2007. Students' perceptions of the weight norm for same sex peers in their year in their school (years 5 through 11) are compared with the aggregate self-reports of weight for these same sex and year cohorts in each school. Variation in perceptions is compared with personal body mass index (BMI) on the basis of self-reported height and weight. RESULTS: A total of 34% of males and 32% of females overestimated peer weight norms by more than 5% (10 kg on average). Similarly, 37% of males and 43% of females underestimated peer weight norms by more than 5% (7 kg on average). For both males and females, overestimating peer weight norms was associated with a greater risk for being overweight and underestimating peer weight norms was associated with a greater risk for being underweight. Perceived peer weight norm was the strongest predictor of BMI among females compared with estimated actual weight norms of peers (based on the mean of self-reported weight) and demographic factors, and one of the two strongest predictors among males in linear regression analyses, including schools as fixed effects. CONCLUSIONS: Pervasive misperceptions of peer weight norms may contribute to unhealthy weight-related behaviors and help perpetuate students' overweight or underweight status. Future research should examine perceptions of other weight-related peer norms and explore what may create misperceptions. Addressing pervasive misperceptions of weight could perhaps be included as a part of interventions aimed at reducing unhealthy weight and related behaviors.

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BACKGROUND: Few weight management clinics have access to indirect calorimetry with which to measure energy expenditure. Instead, they use energy expenditure prediction equations, which were not designed for use in obesity. We aimed to establish the extent to which such equations overestimate and underestimate resting energy expenditure (REE) in overweight and obese individuals. METHODS: We compared the Schofield, Harris & Benedict, James & Lean and World Health Organisation (WHO) REE prediction equations with the clinical gold standard of indirect calorimetry in 28 males and 168 females, with a mean (SD) age of 28.9 (6.4) years and body mass index (BMI) of 19-67 kg m(-2). RESULTS: The mean REE estimated by indirect calorimetry, and the Schofield, Harris & Benedict, James & Lean and WHO equations were 8.09, 8.30, 8.09, 8.37 and 8.23 MJ day(-1) (1934, 1983, 1933, 2001 and 1966 kcal day(-1)), respectively. Although rising BMI exerted only a small effect on the mean differences between indirect calorimetry and the predicted REE [Schofield: +272 kJ (+65 kcal)/10 units BMI, P = 0.02; Harris & Benedict: +42 kJ (+10 kcal)/10 units BMI, P = 0.69; James & Lean: +217 kJ (+52 kcal) 10 units BMI, P = 0.06 and WHO: +42 kJ (+10 kcal) BMI, P = 0.11], the variance among overweight and obese patients of BMI >25 was substantially higher compared to that among normal weight subjects of BMI <25, on whom the equations were based. The estimated REE by Schofield for an individual of BMI 35 kg m(-2), for example, could lie anywhere from 2.78 MJ (661 kcal) above the indirect calorimetry value to 2.59 MJ (618) kcal below it. CONCLUSIONS: Prediction equations offer a quick assessment of energy needs for hypocaloric diets although, in reality, they run the random risk of excessive restriction or further weight gain.

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This article examines the practice of standard varicose vein surgery including sapheno-femoral and sapheno-popliteal ligation, perforator surgery and surgery for recurrent varicose veins. The technique of exposure of the sapheno-femoral junction and the sapheno-popliteal junction is outlined and advice given on avoidance of complications for both. The evidence regarding methods of closure over the ligated sapheno-femoral junction is examined as is the requirement for stripping and the use of different types of stripper. The requirement to strip the small saphenous vein and the extent of dissection necessary in the popliteal fossa is also examined. Complications of standard varicose vein surgery are outlined. The frequency of wound infection, nerve injury, vascular injury and venous thromboembolism are listed and strategies to avoid these complications are examined.

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INTRODUCTION: The objective was to assess the management, and short- and longer-term outcome of patients presenting with an acute blue finger. PATIENTS AND METHODS: This was a retrospective, case-note review and prospective follow-up by telephone and general practitioner enquiry. All patients who presented with sudden onset blue discolouration of a finger within the previous 72 h, with normal radial and ulnar pulses, were included. RESULTS: From 2000 to 2006, 22 patients, 15 female, 7 male, were reviewed. Median age was 56 years (range, 19-88 years). Median time from onset of blue finger was 6 days (range 1 day to 3 months). In most cases (17), no underlying cause was identified. Five patients had an underlying cause; two had symptoms compatible with Raynaud's phenomenon, one patient had signs (later confirmed on MRA) of arterial thoracic outlet syndrome and two had polycythaemia (haemoglobin > 17 g/dl). Otherwise, all laboratory investigations were normal. Upper limb duplex, echocardiogram and 24-h cardiac tapes were normal in all cases. Median follow-up was 19 months. Three patients had recurrent symptoms in the finger. No patient suffered tissue loss or loss of digit(s), and none had stroke or arterial embolisation. CONCLUSIONS: The acute blue finger is a benign condition not suggestive of arterial embolisation. Tissue or digit loss is not a threat and, in the longer term, there is no threat of embolisation to other vascular sites.

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This study retrospectively reviews an 8-year consecutive series of transmetatarsal amputation (TMA) for forefoot ischaemia in diabetic and non-diabetic patients. Forty-one patients had TMA. Peri-operative mortality was 17% (7/41). A healed stump was achieved in 19 patients (46%) and 18 of these patients were independently mobile, or mobile with sticks. Non-diabetic patients (8/12) healed significantly better than diabetics (11/29). Median time to healing was 7 months (range 3-20 months). All non-healed survivors had a higher amputation (14 below-knee, 1 Syme's). A healed TMA gives good mobility, but prediction of who will heal after operation is unreliable. Time to healing is often lengthy, and failed healing results in higher amputation. These issues need to be fully discussed with the patient who is considered for TMA.

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OBJECTIVES: to evaluate the quality of information on the Internet concerning varicose veins. DESIGN: review of retrieved pamphlets and their scoring for educational value. MATERIALS: a sample of 41 documents were retrieved from the Internet using four "search engines". METHODS: characteristics, including country of origin, authorship, length, and presence of references were recorded. Based on factors such as disease summary, treatment options and complications a weighted score was created by two independent observers. RESULTS: eleven documents were published by an academic institution or professional organisation. Twenty-seven documents originated from private practice groups, the source of three was unidentifiable. The median weighted score was 21.5 (interquartile range: 7.5-48.5). Scores originating from non-profit making organisations were significantly higher than those from private practice groups (44.5 vs 13, p=0.04). The length of the document showed a significant positive correlation with its educational quality as measured by the information score (r=0.82, p<0.001). CONCLUSION: there is a plethora of data concerning varicose veins on the Internet. Some documents offer comprehensive information but many are confusing or misleading. Longer pamphlets and information presented by non-profit making organisations are more reliable than short documents and information offered by private medical groups.

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BACKGROUND: Duplex imaging is increasingly used as the only investigation before carotid endarterectomy, but many different criteria exist in the literature for the detection of a severe (70-99 per cent) carotid stenosis. This study aimed to investigate current practice in carotid duplex imaging in Great Britain and Ireland. METHODS: A postal questionnaire was sent to 86 vascular surgical units. RESULTS: The median number of scans performed per year was 450 (range 60-4500). Thirty-six per cent of units who responded used peak systolic : end diastolic velocity ratio to calculate carotid stenosis. Overall, nine different major duplex criteria were used to grade carotid stenosis in 14 different systems of percentage bands. Only 51 per cent of units verified their duplex criteria against angiography. Eighteen per cent of units used two or more different types of duplex scanner and applied the same diagnostic criteria to each machine. CONCLUSION: A wide variation in diagnostic duplex criteria and methods of grading stenosis exists among vascular units. Internal validation is not performed routinely. Standardization of duplex criteria would ensure greater consistency, but would not replace the need for validation of results within each unit.

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OBJECTIVES: to investigate the outcome of patients undergoing axillo-axillary bypass grafting for symptomatic subclavian artery stenoses or occlusions. DESIGN: retrospective case-note review and prospective review of patients available for follow-up. PATIENTS AND METHODS: sixteen patients had axillo-axillary grafts in a 17-year period. Ten patients were available for review and assessed clinically, by measurement of arm blood pressures, and by duplex scanning of their grafts. RESULTS: one patient died and three grafts occluded within 30 days of operation. Nine out of 10 grafts scanned were patent, with three further grafts clinically patent at death. Overall secondary patency was 75% at a combined median follow-up of 56 months (range 12-204 months). Recurrent symptoms occurred in two patients, one with an occluded graft and one with a patent graft. CONCLUSION: axillo-axillary bypass grafts give good long-term symptom-free results.

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OBJECTIVES: To evaluate the changes in quality of life following conventional abdominal aortic aneurysm repair. DESIGN: Prospective study. MATERIALS AND METHODS: Fifty-nine consecutive patients (50 men; nine women) in two surgical centres were investigated preoperatively, and at 6 weeks, 3 months and 6 months postoperatively. Quality of life was measured using the Short Form 36 (SF 36) questionnaire and the York Quality of Life questionnaire, from which the Rosser index was calculated. RESULTS: Rosser index assessment showed restoration of quality of life to preoperative levels by 3 months, and significant improvement at 6 months. Changes in the SF 36 revealed significant improvement in mental health, and physical role limitation at all times postoperatively. Social function worsened at 6 weeks but improved to preoperative levels by 3 and 6 months after surgery. CONCLUSIONS: Quality of life was improved after open aortic aneurysm repair. The time course of recovery shows a predominant improvement between 6 weeks and 3 months postoperatively.

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In a 1-year period, 13 patients underwent duplex-guided compression (DGC) of femoral artery false aneurysms. Of the 13 false aneurysms, 11 arose after cardiac catheterisation, and DGC was successful in 10 (77%) cases. The number of percutaneous cardiological procedures has risen over the past 5 years, and with time a greater proportion of these procedures have become more complex, involving coronary angioplasty or coronary stenting. The rate of vascular complications has risen from 0.2% in 1991-1992 to 0.61% in 1994-1995. Duplex-guided compression has reduced the number of operations performed for the vascular complications of percutaneous cardiological procedures by 50%. No complications have arisen from DGC, and it is recommended as the first line of management for femoral artery false aneurysms after percutaneous cardiological procedures.

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Carotid bifurcation advancement uses the in situ external carotid artery to patch the internal carotid after carotid endarterectomy. This avoids the potential complications of patch rupture and pseudo-aneurysm formation seen with vein and synthetic patches. In 25 cases a Dacron patch was used to close and nine bifurcation advancement closures were compared retrospectively with 30 cases using simple primary closure and 13 using a saphenous vein patch. Follow-up with carotid duplex scanning revealed six restenoses > 50% in the primary closure group, whereas the patch angioplasty and bifurcation advancement groups had no restenoses (P = 0.002). No significant difference in post-endarterectomy flow increase was shown between the patch angioplasty groups and the bifurcation advancement group. Operation times did not differ significantly between the patch closure and the bifurcation advancement groups. Carotid bifurcation advancement is an alternative method of vessel closure with comparable rates of restenosis, post-endarterectomy flow increase, and operation time as compared with conventional patch angioplasty closure techniques.

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OBJECTIVES: To compare percutaneous transluminal angioplasty (PTA) against exercise training in the treatment of stable claudication. DESIGN: Prospective, randomised trial. MATERIALS: Fifty-six patients with unilateral, stable, lower limb claudication assessed prior to randomisation, at 3 monthly intervals for 15 months, and at approximately 6 years follow-up. Thirty-seven patients were available for long term review. OUTCOME MEASURES: Ankle/brachial pressure index (ABPI), treadmill claudication and maximum walking distances, percentage fall in ankle systolic pressure after exercise. RESULTS: Significant increases were seen in ABPI in the patients treated with PTA at all assessment to 15 months. However in terms of improved walking performance, the most significant changes in claudication and maximum walking distance were seen in the exercise training group. At long term follow-up, there was no significant difference between the groups. Subgroup analysis by angiographic site of disease showed greater functional improvement in those patients with disease confined to the superficial femoral artery treated by exercise training. The overall prognosis for the whole group of patients was benign, with only two (4%) undergoing amputation. CONCLUSIONS: Exercise training confers a greater improvement in claudication and maximum walking distance than PTA, especially in patients with disease confined to the superficial femoral artery.

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Phlegmasia caerulea dolens and venous gangrene are rare conditions that tend to occur in association with malignancy. They are characterized by total or near-total occlusion of the venous drainage of the limb, including the microvascular collaterals. Associated mortality and morbidity rates are high, especially when progression to venous gangrene has occurred. Treatment options are limited; elevation and anticoagulation are recommended as first-line management. Experience with thrombolysis has been disappointing although intra-arterial administration of thrombolytic agents may improve results. Thrombectomy cannot be advocated routinely. Little advance in management, or in life and limb salvage, has been made in the past 30 years.

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