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The neutral, homoleptic pyridylphosphininenickel(0) complex [Ni(2-Py-4,6-Ph2-PC5H2)2] (1) has been obtained by reaction of the formal Ni(0) source [(IPr)Ni(H2CâCHSiMe3)2] with 2 equiv of 2-(2'-pyridyl)-4,6-diphenylphosphinine (L). Compound 1 can be oxidized both electrochemically and through the use of ferrocenium salts, to afford the corresponding Ni(I) complexes [1]BF4, [1(THF)]PF6, and [12](BArF4)2. The structures of these salts reveal an interesting dependence on the nature of the anion. While [1]BF4 and [1(THF)]PF6 show trigonal-bipyramidal coordination of Ni in the solid state, [12](BArF4)2 exists as a dinuclear Ni(I) complex and possesses a bridging phosphinine moiety in a rare µ2 mode. Reactions of 1 with halobenzenes highlight the noninnocent behavior of the aromatic phosphinine ligand, leading to the formation of oxidized Ni complexes but not to classical oxidative addition products. The reaction of 1 with bromobenzene affords the λ5 phosphinine 2 and the bipyramidal Ni(I) complex [1]Br, whereas a more unconventional oxidation product 3 is formed from the reaction of 1 and iodobenzene.
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BACKGROUND: Endovascular intervention has emerged as a potential alternative to open surgery in treating common femoral artery (CFA) atherosclerotic disease. The aim of this systematic review was to assess the safety and efficacy of both techniques. METHODS: Thirteen electronic databases from 1980 to 3 January 2018 were searched. Study quality was assessed using the National Institute for Health and Care Excellence Interventional Procedure Programme quality assessment tool. Safety and efficacy outcome measures were analysed. RESULTS: Thirty-one studies reporting 813 endovascular procedures and 3835 endarterectomies were included. Only two small RCTs have been reported. The methodological quality of available studies was generally low and follow-up short. Safety endpoint assessment revealed a similar risk of wound haematoma for endovascular intervention and endarterectomy (5·5 (95 per cent c.i. 0·2 to 17·2) versus 3·9 (1·7 to 6·9) per cent respectively), a lower risk of wound infection with endovascular procedures (0 versus 5·9 (3·4 to 9·0) per cent) and a lower risk of wound lymph leakage (0 versus 5·7 (3·3 to 8·6) per cent). Efficacy endpoint assessment at 1 year identified that endovascular intervention had a lower primary patency rate than endarterectomy (78·8 (73·3 to 83·8) versus 96·0 (92·2 to 98·6) per cent respectively), a higher revascularization rate (16·0 (6·1 to 29·4) versus 5·8 (1·0 to 14·2) per cent) and a similar amputation rate (2·7 (1·2 to 4·8) versus 1·9 (0·7 to 3·8) per cent). CONCLUSION: Endovascular intervention of CFA disease appears to reduce the risk of wound complications but is associated with a lower patency rate and increased rates of subsequent revascularization procedures. Standardization of the endovascular technique and quantification of the proportions of patients suitable for either technique are required.
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Aterosclerose/cirurgia , Procedimentos Endovasculares/métodos , Artéria Femoral/cirurgia , Doença Arterial Periférica/cirurgia , Aterosclerose/mortalidade , Endarterectomia/métodos , Endarterectomia/mortalidade , Procedimentos Endovasculares/mortalidade , Métodos Epidemiológicos , Humanos , Doença Arterial Periférica/mortalidade , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/mortalidade , Resultado do TratamentoRESUMO
BACKGROUND: The effect of sarcopenia based on the total psoas muscle area (TPMA) on CT is inconclusive in patients undergoing abdominal aortic aneurysm (AAA) intervention. The aim of this prospective cohort study was to evaluate morphometric sarcopenia as a method of risk stratification in patients undergoing elective AAA intervention. METHODS: TPMA was measured on preintervention CT images of patients undergoing elective endovascular aneurysm repair (EVAR) or open aneurysm repair. Mortality was assessed in relation to preintervention TPMA using Cox regression analysis, with calculation of hazard ratios at 30 days, 1 year and 4 years. Postintervention morbidity was evaluated in terms of postintervention care, duration of hospital stay and 30-day readmission. Changes in TPMA on surveillance EVAR imaging were also evaluated. RESULTS: In total, 382 patient images acquired between March 2008 and December 2016 were analysed. There were no significant intraobserver and interobserver differences in measurements of TPMA. Preintervention TPMA failed to predict morbidity and mortality at all time points. The mean(s.d.) interval between preintervention and surveillance imaging was 361·3(111·2) days. A significant reduction in TPMA was observed in men on surveillance imaging after EVAR (mean reduction 0·63(1·43) cm2 per m2 ; P < 0·001). However, this was not associated with mortality (adjusted hazard ratio 1·00, 95 per cent c.i. 0·99 to 1·01; P = 0·935). CONCLUSION: TPMA is not a suitable risk stratification tool for patients undergoing effective intervention for AAA.
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Aneurisma da Aorta Abdominal/cirurgia , Angiografia por Tomografia Computadorizada/métodos , Procedimentos Cirúrgicos Eletivos/métodos , Procedimentos Endovasculares/métodos , Músculos Psoas/diagnóstico por imagem , Sarcopenia/diagnóstico por imagem , Idoso , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Aneurisma da Aorta Abdominal/mortalidade , Estudos de Coortes , Procedimentos Cirúrgicos Eletivos/mortalidade , Procedimentos Endovasculares/mortalidade , Feminino , Mortalidade Hospitalar/tendências , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Modelos de Riscos Proporcionais , Estudos Prospectivos , Análise de Regressão , Análise de Sobrevida , Resultado do TratamentoRESUMO
BACKGROUND: Popliteal artery aneurysms (PAAs) comprise up to 85 per cent of all peripheral aneurysms. Few longitudinal studies track their progression. This study aimed to track the growth of asymptomatic PAAs in a hospital-based ultrasound service, and compare models of aneurysm growth. METHODS: This retrospective single-centre cohort study included patients who had a PAA on arterial duplex ultrasound imaging of the lower limbs between 1 January 2011 and 1 January 2016. Progression of PAA size and progression to event or intervention were the primary outcome measures. RESULTS: Some 282 images were analysed: 47 limbs with PAA were included in a cohort of 32 patients (15 had bilateral PAAs). Twenty patients also had an abdominal aortic aneurysm (AAA). Linear multilevel modelling estimated that PAA growth was 2·4 (95 per cent c.i. 1·6 to 3·7) mm a year. Growth was estimated at 0·8 (0·1 to 1·5) mm per year in patients without an AAA and 3·5 (2·9 to 4·2) mm per year in those with a known AAA (previous open repair, previous endovascular aneurysm repair or AAA under surveillance) (P < 0·001). CONCLUSION: Growth rates of PAA were heterogeneous but were optimally predicted by multilevel modelling. Patients with an existing AAA may have faster PAA progression than those without.
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Aneurisma/patologia , Artéria Poplítea/patologia , Idoso , Aneurisma/complicações , Aneurisma/diagnóstico por imagem , Aneurisma da Aorta Abdominal/complicações , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Progressão da Doença , Feminino , Humanos , Masculino , Modelos Cardiovasculares , Artéria Poplítea/diagnóstico por imagem , Estudos Retrospectivos , Fatores de Tempo , Ultrassonografia Doppler DuplaRESUMO
BACKGROUND: Alcohol is a possible risk factor for abdominal aortic aneurysm (AAA), but evidence from individual studies is weak and inconsistent. Existing narrative reviews suggest the possibility of non-linear associations. The aim here was to quantify any association using a systematic literature review, followed by dose-response meta-analysis of prospective studies. METHODS: MEDLINE, Embase and Web of Science were searched systematically to January 2017 for relevant prospective studies of alcohol consumption and AAA risk. Summary estimates of highest versus lowest levels of consumption, and linear and non-linear dose-response curves were quantified using random-effects models. RESULTS: Eleven relevant cohorts were identified describing results from 3580 individuals with among 473 092 participants. Data were extracted from ten cohorts for meta-analyses of high versus low levels of alcohol consumption (risk ratio for AAA 0·93, 95 per cent c.i. 0·78 to 1·11; P = 0·4, I2 = 47 per cent). The linear dose-response risk ratio for AAA, derived from 11 cohorts, was 1·00 (0·97 to 1·04) per 8 g alcohol per day (P = 0·9, I2 = 73 per cent). Non-linear dose-response results showed a tick-shaped curve with lower risk up to 2 units/day, but increasing risk beyond that (P = 0·05). The increase in risk beyond 2 units/day was stronger in men than in women. CONCLUSION: Although the linear dose-response analysis revealed little evidence of an association between alcohol consumption and AAA risk, a tick-shaped trend in the association was observed. This non-linear dose-response analysis revealed reduced risks for alcohol consumption below 2 units/day, masking increased risks for 2 or more units/day.
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Consumo de Bebidas Alcoólicas/efeitos adversos , Aneurisma da Aorta Abdominal/etiologia , Relação Dose-Resposta a Droga , Humanos , Fatores de RiscoRESUMO
Directed evolution is a powerful method for engineering proteins towards user-defined goals and has been used to generate novel proteins for industrial processes, biological research and drug discovery. Typical directed evolution techniques include cellular display, phage display, ribosome display and water-in-oil compartmentalization, all of which physically link individual members of diverse gene libraries to their translated proteins. This allows the screening or selection for a desired protein function and subsequent isolation of the encoding gene from diverse populations. For biotechnological and industrial applications there is a need to engineer proteins that are functional under conditions that are not compatible with these techniques, such as high temperatures and harsh detergents. Cellular High-throughput Encapsulation Solubilization and Screening (CHESS), is a directed evolution method originally developed to engineer detergent-stable G proteins-coupled receptors (GPCRs) for structural biology. With CHESS, library-transformed bacterial cells are encapsulated in detergent-resistant polymers to form capsules, which serve to contain mutant genes and their encoded proteins upon detergent mediated solubilization of cell membranes. Populations of capsules can be screened like single cells to enable rapid isolation of genes encoding detergent-stable protein mutants. To demonstrate the general applicability of CHESS to other proteins, we have characterized the stability and permeability of CHESS microcapsules and employed CHESS to generate thermostable, sodium dodecyl sulfate (SDS) resistant green fluorescent protein (GFP) mutants, the first soluble proteins to be engineered using CHESS.
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Evolução Molecular Direcionada/métodos , Engenharia de Proteínas/métodos , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas de Fluorescência Verde , Concentração de Íons de Hidrogênio , Estabilidade Proteica , Proteínas Recombinantes/metabolismo , Dodecilsulfato de Sódio , Solubilidade , TemperaturaRESUMO
BACKGROUND: Cardiovascular disease (CVD) is the main cause of death in people with abdominal aortic aneurysm (AAA). There is little evidence that screening for AAA reduces all-cause or cardiovascular mortality. The aim of the study was to assess whether subjects with a small or medium AAA (3·0-5·4 cm), without previous history of clinical CVD, had raised levels of CVD biomarkers or increased total mortality. METHODS: This prospective study included subjects with a small or medium AAA and controls, all without a history of clinical CVD. CVD biomarkers (high-sensitivity C-reactive protein, hs-CRP; heart-type fatty acid-binding protein, H-FABP) were measured, and survival was recorded. RESULTS: Of a total of 815 people, 476 with an AAA and 339 controls, a cohort of 86 with small or medium AAA (3-5·4 cm) and 158 controls, all with no clinical history of CVD, were identified. The groups were matched for age and sex. The AAA group had higher median (i.q.r.) levels of hs-CRP (2·8 (1·2-6·0) versus 1·3 (0·5-3·5) mg/l; P < 0·001) and H-FABP (4·6 (3·5-6·0) versus 4·0 (3·3-5·1) µg/l; P = 0·011) than controls. Smoking was more common in the AAA group; however, hs-CRP and H-FABP levels were not related to smoking. Mean survival was lower in the AAA group: 6·3 (95 per cent confidence interval (c·i.) 5·6 to 6·9) years versus 8·0 (7·6 to 8·1) years in controls (P < 0·001). Adjusted mortality was higher in the AAA group (hazard ratio 3·41, 95 per cent c·i. 2·11 to 9·19; P < 0·001). CONCLUSION: People with small or medium AAA and no clinical symptoms of CVD have higher levels of hs-CRP and H-FABP, and higher mortality compared with controls. They should continue to receive secondary prevention against CVD.
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Doenças Cardiovasculares/mortalidade , Idoso , Idoso de 80 Anos ou mais , Aneurisma da Aorta Abdominal/mortalidade , Biomarcadores/metabolismo , Proteína C-Reativa/metabolismo , Inglaterra/epidemiologia , Métodos Epidemiológicos , Proteína 3 Ligante de Ácido Graxo , Proteínas de Ligação a Ácido Graxo/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , PrognósticoRESUMO
Globally, dung beetles (Scarabaeidae: Scarabaeinae) are linked to many critical ecosystem processes involving the consumption and breakdown of mammal dung. Endemic New Zealand dung beetles (Canthonini) are an anomaly, occurring at high abundance and low diversity on an island archipelago historically lacking terrestrial mammals, except bats, and instead dominated by birds. Have New Zealand's dung beetles evolved to specialise on bird dung or carrion, or have they become broad generalist feeders? We test dietary preferences by analysing nitrogen isotope ratios of wild dung beetles and by performing feeding behaviour observations of captive specimens. We also use nitrogen and carbon stable isotopes to determine if the dung beetle Saphobius edwardsi will consume marine-derived carrion. Nitrogen isotope ratios indicated trophic generalism in Saphobius dung beetles and this was supported by behavioural observations where a broad range of food resources were utilised. Alternative food resource use was further illustrated experimentally by nitrogen and carbon stable isotope signatures of S. edwardsi, where individuals provided with decomposed squid had δ(15)N and δ(13)C values that had shifted toward values associated with marine diet. Our findings suggest that, in the absence of native mammal dung resources, New Zealand dung beetles have evolved a generalist diet of dung and carrion. This may include marine-derived resources, as provided by the seabird colonies present in New Zealand forests before the arrival of humans. This has probably enabled New Zealand dung beetles to persist in indigenous ecosystems despite the decline of native birds and the introduction of many mammal species.
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Evolução Biológica , Aves/fisiologia , Besouros/fisiologia , Dieta , Ecossistema , Análise de Variância , Animais , Isótopos de Carbono/análise , Fezes/química , Comportamento Alimentar/fisiologia , Processamento de Imagem Assistida por Computador , Nova Zelândia , Isótopos de Nitrogênio/análise , Gravação em VídeoRESUMO
BACKGROUND: Repair of an abdominal aortic aneurysm (AAA) is undertaken to prevent rupture. Intervention is by either open repair (OR) or a more minimally invasive endovascular repair (EVAR). Quality-of-life (QoL) analysis is an important health outcome and a number of single studies have assessed QoL following OR and EVAR. This was a meta-analysis of published studies to assess the effect of an intervention on QoL in patients with an AAA. METHODS: A systematic literature search was undertaken for studies prospectively reporting QoL analysis in patients with an AAA undergoing elective intervention. A multivariable meta-analysis model was developed in which the outcomes were mean changes in QoL scores over time, both for all AAA repairs (OR and EVAR) and comparing OR with EVAR. RESULTS: Data were collated from 16 studies (14 OR, 12 EVAR). The results suggested that treating an AAA had an effect on patient-reported QoL, evident from the statistically significant changes predominantly in domains assessing physical ability and pain. QoL was affected most within the first 3 months after any form of intervention, and was more pronounced following OR. Furthermore, a deterioration in the Physical Component Summary score following an AAA repair (either OR or EVAR) was evident at 12 months after intervention. CONCLUSION: Treating an AAA deleteriously affects patient-reported QoL over the first year following intervention.
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Aneurisma da Aorta Abdominal/cirurgia , Procedimentos Endovasculares , Qualidade de Vida , Idoso , Ensaios Clínicos como Assunto , Procedimentos Cirúrgicos Eletivos , Feminino , Humanos , Masculino , Saúde Mental , Dor Pós-Operatória/etiologia , Estudos Prospectivos , Resultado do TratamentoRESUMO
BACKGROUND: Ongoing angiogenesis is implicated in the inflammatory environment that characterizes abdominal aortic aneurysm (AAA). Although lymphangiogenesis has been associated with chronic inflammatory conditions, it has yet to be demonstrated in AAA. The aim was to determine the presence of lymphangiogenesis and to delineate the relationship between inflammation and neovascularization in AAA tissue. METHODS: AAA samples and preoperative computed tomography images were obtained from patients undergoing elective AAA repair. Control samples were age-matched abdominal aortic tissue. Specific immunostains for blood vessels (CD31, CD105), lymphatic vessels (D2-40), vascular endothelial growth factor (VEGF) A and VEGF receptor (VEGFR) 3 allowed characterization and quantitation of vasculature. RESULTS: The AAA wall contained high levels of inflammatory infiltrate; microvascular densities of blood (P < 0·001) and lymphatic (P = 0·003) vessels were significantly increased in AAA samples compared with controls. Maximal AAA vascularity was observed in inflammatory areas, with vessels that stained positively for CD31 (ρ = 0·625, P = 0·017), CD105 (ρ = 0·692, P = 0·009) and D2-40 (ρ = 0·675, P = 0·008) correlating positively with the extent of inflammation. Increased VEGFR-3 and VEGF-A expression was also evident within inflammatory AAA areas. CONCLUSION: These findings demonstrated lymphatic vessel involvement in end-stage AAA disease, which was associated with the degree of inflammation, and confirmed the involvement of neovascularization.
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Aneurisma da Aorta Abdominal/patologia , Linfangiogênese/fisiologia , Idoso , Aortite/patologia , Biomarcadores/sangue , Estudos de Casos e Controles , Feminino , Humanos , Vasos Linfáticos/patologia , Masculino , Microvasos/patologia , Neovascularização Patológica/patologia , Trombose/patologia , Tomografia Computadorizada por Raios X , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Vascular Ehlers-Danlos Syndrome (EDS) is a rare autosomal dominant condition resulting from a defect in type III procollagen synthesis. This causes the development of severe vascular pathologies, including arterial rupture and pseudoaneurysm formation. We present a case of a young boy previously diagnosed with vascular EDS due to a Gly975Val substitution in the collagen α1(III) chain presenting with a common femoral artery dissection secondary to minimal trauma. This was managed conservatively with serial duplex scans and gentle mobilization. At follow up the patient had returned to normal activities, with MRA and duplex scans showing complete resolution of the dissection.
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Síndrome de Ehlers-Danlos/reabilitação , Artéria Femoral/lesões , Criança , Síndrome de Ehlers-Danlos/diagnóstico , Artéria Femoral/diagnóstico por imagem , Humanos , Masculino , RadiografiaRESUMO
Plasmid encoded replication initiation (Rep) proteins recruit host helicases to plasmid replication origins. Previously, we showed that RepD recruits directionally the PcrA helicase to the pC221 oriD, remains associated with it, and increases its processivity during plasmid unwinding. Here we show that RepD forms a complex extending upstream and downstream of the core oriD. Binding of RepD causes remodelling of a region upstream from the core oriD forming a 'landing pad' for the PcrA. PcrA is recruited by this extended RepD-DNA complex via an interaction with RepD at this upstream site. PcrA appears to have weak affinity for this region even in the absence of RepD. Upon binding of ADPNP (non-hydrolysable analogue of ATP), by PcrA, a conformational rearrangement of the RepD-PcrA-ATP initiation complex confines it strictly within the boundaries of the core oriD. We conclude that RepD-mediated recruitment of PcrA at oriD is a three step process. First, an extended RepD-oriD complex includes a region upstream from the core oriD; second, the PcrA is recruited to this upstream region and thirdly upon ATP-binding PcrA relocates within the core oriD.
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Proteínas de Bactérias/metabolismo , DNA Helicases/metabolismo , Proteínas de Ligação a DNA/metabolismo , Plasmídeos/genética , Origem de Replicação , Staphylococcus aureus/genética , Trifosfato de Adenosina/metabolismo , Sequência de Bases , Pegada de DNA , DNA Bacteriano/química , DNA Bacteriano/metabolismo , DNA Bacteriano/ultraestrutura , Desoxirribonuclease I , Exodesoxirribonucleases , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Ligação ProteicaRESUMO
OBJECTIVE: Neprilysin (NEP), a zinc metalloendopeptidase, has a role in blood pressure control and lipid metabolism. The present study tested the hypothesis that NEP is associated with insulin resistance and features of the metabolic syndrome (MetS) in a study of 318 healthy human subjects and in murine obesity, and investigated NEP production by adipocytes in-vitro. METHODS AND RESULTS: In 318 white European males, plasma NEP was elevated in the MetS and increased progressively with increasing MetS components. Plasma NEP activity correlated with insulin, homoeostasis model assessment and body mass index (BMI) in all subjects (P<0.01). Quantitative reverse transcriptase PCR (RT-PCR) and western blotting showed that in human pre-adipocytes NEP expression is upregulated 25- to 30-fold during differentiation into adipocytes. Microarray analysis of mRNA from differentiated human adipocytes confirmed high-NEP expression comparable with adiponectin and plasminogen activator inhibitor-1. In a murine model of diet-induced insulin resistance, plasma NEP levels were significantly higher in high-fat diet (HFD)-fed compared with normal chow diet (NCD)-fed animals (1642 ± 529 and 820 ± 487 pg µl(-1), respectively; P<0.01). Tissue NEP was increased in mesenteric fat in HFD compared with NCD-fed mice (P<0.05). NEP knockout mice did not display any changes in insulin resistance, glucose tolerance, or body and epididymal fat pad weight compared with wild-type mice. CONCLUSION: In humans, NEP activity correlated with BMI and measures of insulin resistance with increasing levels in subjects with multiple cardiovascular risk factors. NEP protein production in human adipocytes increased during cell differentiation and plasma and adipose tissue levels of NEP were increased in obese insulin-resistant mice. Our results indicate that NEP associates with cardiometabolic risk in the presence of insulin resistance and increases with obesity.
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Adipócitos/metabolismo , Índice de Massa Corporal , Doenças Cardiovasculares/enzimologia , Resistência à Insulina , Síndrome Metabólica/enzimologia , Neprilisina/metabolismo , Obesidade/enzimologia , Animais , Western Blotting , Doenças Cardiovasculares/etiologia , Doenças Cardiovasculares/fisiopatologia , Criança , Gorduras na Dieta/administração & dosagem , Humanos , Masculino , Síndrome Metabólica/etiologia , Síndrome Metabólica/fisiopatologia , Camundongos , Camundongos Knockout , Neprilisina/sangue , Neprilisina/genética , Obesidade/complicações , Obesidade/fisiopatologia , Análise Serial de Proteínas , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
BACKGROUND: Abdominal aortic aneurysm (AAA) screening and surveillance programmes use ultrasound imaging to measure the anteroposterior (AP) diameter of the infrarenal aorta. The aim of this study was to examine potential observer bias and variability in ultrasound measurements. METHODS: Studies were identified for review via a MEDLINE database search (1966-2009). References supplied in accessed papers were also checked for potential relevance. Consistent search terminology, and inclusion and exclusion criteria were used to ensure quality of data. Nine papers were available to review. RESULTS: Variation in intraobserver repeatability and interobserver reproducibility was identified. Six studies reported intraobserver repeatability coefficients for AP aortic diameter measurements of 1·6-4·4 mm. These were below the 5-mm level regarded as acceptable by the UK and USA AAA screening programmes. Five studies had interobserver reproducibility below the level of 5 mm. Four studies, however, reported poor reproducibility (range from -2 to +5·2 to -10·5 to +10·4); these differences may have had a significant clinical impact on screening and surveillance. CONCLUSION: The studies used different methodologies with no standardized measurement techniques. Measurements were taken by observers from different medical disciplines of varying grade and levels of training. Standard training and formal quality assurance of ultrasound measurements are important components of an effective AAA screening programme.
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Aorta Abdominal/diagnóstico por imagem , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Reprodutibilidade dos Testes , UltrassonografiaRESUMO
The first demonstration of a full-scale working undulator module suitable for future TeV-scale positron-electron linear collider positron sources is presented. Generating sufficient positrons is an important challenge for these colliders, and using polarized e(+) would enhance the machine's capabilities. In an undulator-based source polarized positrons are generated in a metallic target via pair production initiated by circularly polarized photons produced in a helical undulator. We show how the undulator design is developed by considering impedance effects on the electron beam, modeling and constructing short prototypes before the successful fabrication, and testing of a final module.
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OBJECTIVES: The United Kingdom abdominal aortic aneurysm (AAA) screening programme refers aneurysms with ultrasound (US) diameters of ≥5.5 cm to vascular services for consideration of computed tomography (CT) and intervention. We investigated the discrepancy between US and CT, implications on clinical decisions and question at which stage CT be used. DESIGN/METHODS: AAA USs over 5 years were retrospectively analysed. Patients included had aneurysms measuring ≥5 cm on US with subsequent CT within 2 months (n = 123). Based on maximum US diameters, 44 patients had aneurysms between 5 and 5.4 cm (group I) and 79 patients ≥5.5 cm (group II). Results were cross-referenced. Correlation and limits of agreement were calculated. Two radiologists re-measured 44 pairs of CT/US scans and the inter-observer bias in determining discrepancies between imaging modalities calculated. RESULTS: Mean difference between imaging modalities was 0.21 cm (±0.39 cm, p < 0.001). Limits of agreement were -0.55 to 0.96 cm, exceeding clinical acceptability. Mean difference was higher and significant in group I (0.39 cm, p < 0.001) compared to group II (0.10 cm, p > 0.05). Seventy-percent of group I patients had CT scans revealing diameters of ≥5.5 cm. Inter-observer bias was not significant. CONCLUSION: Significant differences between imaging modalities, more in US diameters of below 5.5 cm, exist. We recommend AAAs measuring ≥5 cm on US should undergo earlier referral to a vascular service and CT.
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Aneurisma da Aorta Abdominal/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Idoso , Aneurisma da Aorta Abdominal/terapia , Aortografia , Feminino , Humanos , Masculino , Variações Dependentes do Observador , Seleção de Pacientes , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade , UltrassonografiaRESUMO
OBJECTIVE: The aim of this review is to delineate the association between abdominal aortic aneurysms (AAAs) and diabetes mellitus. Mechanisms for the underlying association are then discussed. METHODS: A systematic review of the English-language literature using PubMed, EMBASE and Cochrane databases was undertaken up to September 2009. Studies reporting appropriate prevalence data were identified and a meta-analysis performed. RESULTS: Eleven studies were identified. The prevalence of diabetes mellitus in studied patients with AAA ranged from 6% to 14%. The prevalence of diabetes in control patients without AAA ranged from 17% to 36%. Pooled analysis suggested a reduced rate of diabetes amongst people with AAA compared to those without (OR 0.65, 0.60-0.70, p<0.001). CONCLUSIONS: Studies so far suggest a protective role for diabetes on the development of AAA. Further research is required to demarcate the underlying mechanisms for this possible association.
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Aneurisma da Aorta Abdominal/epidemiologia , Complicações do Diabetes/epidemiologia , Diabetes Mellitus/epidemiologia , Aneurisma da Aorta Abdominal/complicações , Humanos , PrevalênciaRESUMO
Live donor renal transplantation remains the best treatment option for end stage renal failure in pediatric patients (1-3). Better understanding of the hemodynamics of donor-recipient size discrepancy and advances in interventional techniques with improved surgical techniques have decreased the incidence and severity of surgical complications and enhanced graft survival (1, 2). We describe a rare complication occurring intra-operatively in a pediatric renal transplant resulting in acute limb ischemia and the surgical option taken.
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Isquemia/patologia , Transplante de Rim/métodos , Extremidade Inferior/patologia , Complicações Pós-Operatórias/diagnóstico , Doença Aguda , Pré-Escolar , Humanos , Artéria Ilíaca/patologia , Imunossupressores , Isquemia/etiologia , Transplante de Rim/efeitos adversos , Doadores Vivos , Masculino , Modelos Anatômicos , Trombose/patologiaRESUMO
BACKGROUND: : The presence of an abdominal aortic aneurysm (AAA) independently predicts cardiovascular disease (CVD) and its complications. Levels of plasma markers of fibrin turnover are raised in men with a large AAA (at least 5.5 cm) and predict CVD risk in healthy subjects. This study examined fibrin turnover in men with a small AAA. METHODS: : Seventy-five men with a small AAA (30-55 mm) were compared with 90 controls matched for age, sex and race. Haemostatic and fibrinolytic parameters were assessed. RESULTS: : Men with a small AAA had higher mean levels of fibrinogen (2.92 versus 2.59 g/l; P = 0.019), thrombin-antithrombin (TAT) complex (4.57 versus 1.89 ng/ml; P < 0.001), prothrombin F1 + 2 (1.13 versus 0.82 ng/ml; P = 0.004) and D-dimer (346.7 versus 120.2 ng/ml; P < 0.001). All markers correlated with maximum aortic diameter determined by ultrasonography. On multivariable regression the association between presence of an AAA and fibrinogen, TAT complex, prothrombin F1 + 2 and D-dimer levels remained significant after adjustment for confounding influences. CONCLUSION: : Fibrin turnover was increased in these men with a small AAA, independently of concomitant CVD, conventional risk factors and inflammatory markers. Enhanced fibrin turnover may contribute to the risk of cardiac complications in this group.
Assuntos
Aneurisma da Aorta Abdominal/sangue , Fibrina/metabolismo , Fibrinólise/fisiologia , Hemostasia/fisiologia , Idoso , Antitrombina III/metabolismo , Aneurisma da Aorta Abdominal/patologia , Doenças Cardiovasculares/etiologia , Produtos de Degradação da Fibrina e do Fibrinogênio/metabolismo , Fibrinogênio/metabolismo , Humanos , Masculino , Peptídeo Hidrolases/metabolismo , Análise de Regressão , Fatores de RiscoRESUMO
Background: Juxtarenal abdominal aortic aneurysms pose a significant challenge whether managed endovascularly or by open surgery. Fenestrated endovascular aneurysm repair (FEVAR) is now well established, but few studies have compared it with open surgical repair (OSR). The aim of this systematic review was to compare short- and long-term outcomes of FEVAR and OSR for the management of juxtarenal aortic aneurysms. Methods: A literature search was conducted of the Ovid Medline, EMBASE and PubMed databases. Reasons for exclusion were series with fewer than 20 patients, studies published before 2007 and those concerning ruptured aneurysms. Owing to variance in definitions, the terms 'juxta/para/suprarenal' were used; thoracoabdominal aortic aneurysms were excluded. Primary outcomes were 30-day/in-hospital mortality and renal insufficiency. Secondary outcomes included major complication rates, rate of reintervention and rates of endoleak. Results: Twenty-seven studies were identified, involving 2974 patients. Study designs included 11 case series, 14 series within retrospective cohort studies, one case-control study and a single prospective non-randomized trial. The pooled early postoperative mortality rate following FEVAR was 3·3 (95 per cent c.i. 2·0 to 5·0) per cent, compared with 4·2 (2·9 to 5·7) per cent after OSR. After FEVAR, the rate of postoperative renal insufficiency was 16·2 (10·4 to 23·0) per cent, compared with 23·8 (15·2 to 33·6) per cent after OSR. The major early complication rate following FEVAR was 23·1 (16·8 to 30·1) per cent versus 43·5 (34·4 to 52·8) per cent after OSR. The rate of late reintervention after FEVAR was higher than that after OSR: 11·1 (6·7 to 16·4) versus 2·0 (0·6 to 4·3) per cent respectively. Conclusion: No significant difference was noted in 30-day mortality; however, FEVAR was associated with significantly lower morbidity than OSR. Long-term durability is a concern, with far higher reintervention rates after FEVAR.
Antecedentes: Los aneurismas de la aorta abdominal yuxtarrenal plantean un gran reto sobre si tratarlos de forma endovascular o mediante cirugía abierta. La reparación del aneurisma con endoprótesis fenestrada (fenestrated endovascular aneurysm repair, FEVAR) no esta consolidada, sin embargo, algunos pocos estudios, la comparan con la reparación quirúrgica por vía abierta (open surgical repair, OSR). El objetivo de esta revisión sistemática fue comparar los resultados a corto y largo plazo de FEVAR y OSR para el tratamiento de los aneurismas aórticos yuxtarrenales. Métodos: Se llevó a cabo una búsqueda de la literatura en las bases de datos Ovid Medline, EMBASE y Pubmed. Las razones para exclusión fueron series con menos de 20 pacientes, aquellas publicadas antes de 2007 y los trabajos sobre aneurismas rotos. Debido a las diferencias en las definiciones, se utilizaron los términos "yuxta/para/suprarrenal"; se excluyeron los aneurismas de la aorta tóracoabdominal. Los resultados primarios fueron la mortalidad a 30 días/intrahospitalaria y la insuficiencia renal. Los resultados secundarios incluyeron las tasas de complicaciones mayores, tasa de reintervención y tasas de fugas internas. Resultados: Se identificaron un total de 27 estudios, que incluían 2.974 pacientes. Los diseños de los estudios incluían 11 series de casos, 12 estudios de cohortes retrospectivos, un estudio casocontrol y un único ensayo no aleatorizado prospectivo. La mortalidad postoperatoria precoz agrupada tras FEVAR fue del 3,3% (i.c. del 95% 2,05,0), comparado con el 4,2% (i.c. del 95% 2,95,7) tras OSR. Después de FEVAR, la tasa de insuficiencia renal postoperatoria fue del 16,2% (i.c. del 95% 10,423,0) comparada con el 23,8% (i.c. del 95% 15,233,6) después de OSR. La tasa de complicaciones mayores precoces tras FEVAR fue del 23,1% (i.c. del 95% 16,830,1) comparada con el 43,5% (i.c. del 95% 34,452,8) después de OSR. La tasa de reintervención tardía tras FEVAR fue superior que tras OSR: 11,1% (i.c. del 95% 6,716,4) y 2,0% (i.c. del 95% 0,64,3), respectivamente. Conclusión: No se observaron diferencias significativas en la mortalidad a los 30 días, sin embargo, FEVAR presentó una morbilidad significativamente menor que OSR. La durabilidad a largo plazo es una preocupación con muchas mayores tasas de reintervención después de FEVAR.