Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 83
Filtrar
1.
Anaesthesia ; 78(6): 747-757, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37096456

RESUMO

Vagus nerve stimulation is a well-established treatment option for patients with drug-resistant epilepsy and has an expanding range of other clinical indications. Side effects of vagus nerve stimulation therapy include: cough; voice changes; vocal cord adduction; rarely, obstructive sleep apnoea; and arrhythmia. Patients with implanted vagus nerve stimulation devices may present for unrelated surgery and critical care to clinicians who are unfamiliar with their function and safe management. These guidelines have been formulated by multidisciplinary consensus based on case reports, case series and expert opinion to support clinicians in the management of patients with these devices. The aim is to provide specific guidance on the management of vagus nerve stimulation devices in the following scenarios: the peri-operative period; peripartum period; during critical illness; and in the MRI suite. Patients should be aware of the importance of carrying their personal vagus nerve stimulation device magnet with them at all times to facilitate urgent device deactivation if necessary. We advise that it is generally safer to formally deactivate vagus nerve stimulation devices before general and spinal anaesthesia. During periods of critical illness associated with haemodynamic instability, we also advise cessation of vagus nerve stimulation and early consultation with neurology services.


Assuntos
Epilepsia , Estimulação do Nervo Vago , Humanos , Estimulação do Nervo Vago/efeitos adversos , Epilepsia/etiologia , Estado Terminal , Arritmias Cardíacas , Anestesistas , Resultado do Tratamento
2.
Interv Neuroradiol ; 28(2): 213-218, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34121488

RESUMO

BACKGROUND AND PURPOSE: Aspiration is a successful technique used in thrombectomy for acute stroke. It is contingent upon the appropriate position of the aspiration catheter, so that it is in contact with the thrombus. However, navigating the craniocervical vasculature is challenging is some patients. The wedge microcatheter (MicroVention®) is designed to reduce the gap between the microcatheter and the SofiaPlus 6F catheter for ease of advancement. The purpose of this study is to describe our initial experience with the wedge microcatheter. MATERIALS AND METHODS: A retrospective review of 38 consecutive patients in whom the wedge microcatheter was used during thrombectomy was performed to determine whether the wedge microcatheter was successful in delivering the Sofia catheter to the desired location. RESULTS: We have found this device to be successful in delivering the aspiration catheter to the correct position in 97% (N = 37) of cases. It was used predominantly to pass the origin of branching vessels and also to navigate the tortuous cavernous and petrous segments of the ICA. CONCLUSION: The wedge microcatheter is a successful tool in delivering the aspiration catheter to the desired vessel for revascularisation.


Assuntos
Isquemia Encefálica , Procedimentos Endovasculares , Acidente Vascular Cerebral , Trombose , Isquemia Encefálica/cirurgia , Catéteres , Procedimentos Endovasculares/métodos , Humanos , Estudos Retrospectivos , Acidente Vascular Cerebral/cirurgia , Trombectomia/métodos , Resultado do Tratamento
3.
BMC Geriatr ; 21(1): 415, 2021 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-34229623

RESUMO

BACKGROUND: Older age and comorbid burden are both associated with adverse outcomes in SARS-CoV-2, but it is not known whether the association between comorbid burden and adverse outcomes differs in older and younger adults. OBJECTIVE: To compare the relationship between comorbid burden and adverse outcomes in adults with SARS-CoV-2 of different ages (18-64, 65-79 and ≥ 80 years). DESIGN, SETTING, AND PARTICIPANTS: Observational longitudinal cohort study of 170,528 patients who tested positive for SARS-CoV-2 in the US Department of Veterans Affairs (VA) Health Care System between 2/28/20 and 12/31/2020 who were followed through 01/31/2021. MEASUREMENTS: Charlson Comorbidity Index (CCI); Incidence of hospitalization, intensive care unit (ICU) admission, mechanical ventilation, and death within 30 days of a positive SARS-CoV-2 test. RESULTS: The cumulative 30-day incidence of death was 0.8% in cohort members < 65 years, 7.1% in those aged 65-79 years and 20.6% in those aged ≥80 years. The respective 30-day incidences of hospitalization were 8.2, 21.7 and 29.5%, of ICU admission were 2.7, 8.6, and 11% and of mechanical ventilation were 1, 3.9 and 3.2%. Median CCI (interquartile range) ranged from 0.0 (0.0, 2.0) in the youngest, to 4 (2.0, 7.0) in the oldest age group. The adjusted association of CCI with all outcomes was attenuated at older ages such that the threshold level of CCI above which the risk for each outcome exceeded the reference group (1st quartile) was lower in younger than in older cohort members (p < 0.001 for all age group interactions). LIMITATIONS: The CCI is calculated based on diagnostic codes, which may not provide an accurate assessment of comorbid burden. CONCLUSIONS: Age differences in the distribution and prognostic significance of overall comorbid burden could inform clinical management, vaccination prioritization and population health during the pandemic and argue for more work to understand the role of age and comorbidity in shaping the care of hospitalized patients with SARS-CoV-2.


Assuntos
COVID-19 , SARS-CoV-2 , Idoso , Hospitalização , Humanos , Unidades de Terapia Intensiva , Estudos Longitudinais , Pessoa de Meia-Idade , Pandemias
4.
Clin Radiol ; 74(12): 950-955, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31521325

RESUMO

AIMS: To determine the experience of a regional stroke referral centre of external referrals for endovascular thrombectomy (EVT) in patients with symptoms of acute ischaemic stroke (AIS) and large vessel occlusion (LVO). MATERIALS AND METHODS: Data were collected prospectively over two 4-month periods (2017-2018) on consecutive external referrals for EVT. Baseline demographics, imaging findings, and key time parameters were recorded. Reasons for not transferring patients and for not performing EVT were recorded. Key time intervals were calculated and compared between the transferred and non-transferred group with and without intracranial occlusion and between the transferred patients who underwent thrombectomy and those who did not. RESULTS: Two hundred and sixty-two patients were referred. Sixty-one percent (n=159) were accepted and transferred for treatment. Of those transferred, 86% (n=136) had EVT. Fourteen percent (n=23) were unsuitable for EVT on arrival due to no vessel occlusion (48% n=11), poor Alberta Stroke Program Early CT Score (ASPECTS)/established infarct (30%, n=7) haemorrhage (9%, n=2), and clinical recovery (13% n=3). One hundred and three patients (39%) were ineligible for EVT following phone discussion due to absence of intracranial occlusion (59%, n=61), low ASPECTS (22%, n=23), distal occlusion (4%, n=4), low/improving National Institutes of Health Stroke Scale (NIHSS; 10.7%, n=11), and poor modified Rankin Scale (mRS) at baseline (3%, n=3). Patients with LVO but not transferred had longer onset to hospital arrival time compared with those transferred 151.5 versus 91 minutes (p<0.005), with a trend also toward a longer door to CT/CTA 40 minutes versus 30 minutes (p=0.142). CONCLUSION: These data provide valuable insights into the service provision of a comprehensive stroke network. The present rates of EVT and futile transfers are modest compared to published data. Access to neuroradiology and specialised stroke assessment is crucial to optimise time to treatment.


Assuntos
Encaminhamento e Consulta/estatística & dados numéricos , Acidente Vascular Cerebral/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Transferência de Pacientes/estatística & dados numéricos , Índice de Gravidade de Doença , Acidente Vascular Cerebral/diagnóstico por imagem , Trombectomia/estatística & dados numéricos , Fatores de Tempo
5.
AJNR Am J Neuroradiol ; 40(8): 1335-1341, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31320463

RESUMO

BACKGROUND AND PURPOSE: Direct aspiration is a recognized technique for revascularization in large-vessel ischemic strokes. There is ongoing debate regarding its efficacy compared with stent retrievers. Every delay in achieving revascularization and a decrease in reperfusion rates reduces the likelihood of patients achieving functional independence. We propose a standardized setup technique for aspiration-first for all anterior circulation thrombectomy procedures for increasing speed and recanalization rates. MATERIALS AND METHODS: We analyzed 127 consecutive patients treated by a standardized approach to thrombectomy with an intention to perform aspiration-first compared with 127 consecutive patients treated with a stent retriever-first approach. Key time metrics evaluated included groin to first angiogram, first angiogram to reperfusion, groin to first reperfusion, and length of the procedure. The degree of successful recanalization (TICI 2b-3) and the number of passes were compared between the 2 groups. RESULTS: In 127 patients who underwent the standardized technique, the median time from groin puncture to first reperfusion was 18 minutes compared with 26 minutes (P < .001). The duration of the procedure was shorter compared with the stent retriever group (26 minutes in the aspiration first group versus 47 minutes, P < .001) and required fewer passes (mean, 2.4 versus 3.1; P < .05). A higher proportion of patients had a TICI score of 2b-3 in the aspiration-first group compared with stent retriever group (96.1% versus 85.8%, P < .005). CONCLUSIONS: Our study highlights the increasing speed and recanalization rates achieved with fewer passes in a standardized approach to thrombectomy with an intention to attempt aspiration-first. Any attempt to reduce revascularization time and increase successful recanalization should be used.


Assuntos
Reperfusão/métodos , Acidente Vascular Cerebral/cirurgia , Trombectomia/métodos , Trombectomia/normas , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reperfusão/instrumentação , Reperfusão/normas , Trombectomia/instrumentação , Resultado do Tratamento
6.
Ir Med J ; 111(9): 818, 2018 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-30556666

RESUMO

Aims This study aimed to identify the physiotherapy exercise rehabilitation services available to patients with cancer in Ireland and to identify barriers to the provision of services. Methods Physiotherapy department managers in specialised cancer centres, public and private hospitals and palliative care settings were surveyed to establish the availability of exercise rehabilitation services for patients with cancer. Results Of 40 managers contacted, 24 responded providing information about 26 services. Ten services employed a dedicated oncology physiotherapist. Exercise classes were offered to patients with cancer by five services, primarily within the palliative care setting. In the 17 hospitals which provided surgery, ten provided oncology specific post-operative exercise rehabilitation and one offered a prehabilitation programme. Limited human and physical resources and absence of established physiotherapy pathways were cited barriers to service provision. Conclusion Exercise rehabilitation is not an element of standard care for patients with cancer in Ireland.


Assuntos
Terapia por Exercício/estatística & dados numéricos , Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Neoplasias/reabilitação , Cuidados Paliativos/estatística & dados numéricos , Serviço Hospitalar de Fisioterapia/estatística & dados numéricos , Modalidades de Fisioterapia/estatística & dados numéricos , Terapia por Exercício/métodos , Humanos , Entrevistas como Assunto , Irlanda/epidemiologia , Cuidados Paliativos/métodos
7.
Neuroradiology ; 60(10): 995-1012, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30097693

RESUMO

Central or neurogenic diabetes insipidus (CDI) is due to deficient synthesis or secretion of antidiuretic hormone (ADH), also known as arginine vasopressin peptide (AVP). It is clinically characterised by polydipsia and polyuria (urine output > 30 mL/kg/day) of dilute urine (< 250 mOsm/L). It is the result of a defect in one of more sites involving the hypothalamic osmoreceptors, supraoptic or paraventricular nuclei of the hypothalamus, median eminence of the hypothalamus, infundibulum or the posterior pituitary gland. A focused MRI pituitary gland or sella protocol is essential. There are several neuroimaging correlates and causes of CDI, illustrated in this review. The most common causes are benign or malignant neoplasms of the hypothalamic-pituitary axis (25%), surgery (20%), head trauma (16%) or familial causes (10%). No cause is identified in up to 30% of cases. Knowledge of the anatomy and physiology of the hypothalamo-neurohypophyseal axis is crucial when evaluating a patient with CDI. Establishing the aetiology of CDI with MRI in combination with clinical and biochemical assessment facilitates appropriate targeted treatment. The aim of the pictorial review is to illustrate the wide variety of causes of CDI on neuroimaging, highlight the optimal MRI protocol and to revise the detailed neuroanatomy and neurophysiology required to interpret these studies.


Assuntos
Diabetes Insípido Neurogênico/diagnóstico por imagem , Diabetes Insípido Neurogênico/etiologia , Imageamento por Ressonância Magnética/métodos , Neuroimagem/métodos , Humanos , Sistema Hipotálamo-Hipofisário/anatomia & histologia , Sistema Hipotálamo-Hipofisário/fisiologia
8.
J Intern Med ; 282(6): 537-545, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28875550

RESUMO

BACKGROUND AND OBJECTIVES: Benefit from endovascular thrombectomy (EVT) for large-vessel occlusion (LVO) acute ischaemic stroke (AIS) is well demonstrated. Furthermore, emerging evidence supports efficacy in appropriately selected patients treated beyond current recommendations of 6 h. We evaluated clinical outcomes in patients undergoing late EVT at our institution. METHODS: Retrospective review of prospectively collected clinical database on 355 patients who underwent EVT for LVO AIS. Data collected consisted of patient demographics, radiological findings and outcome details. Outcomes, including 90-day functional status, recanalization, symptomatic intracranial haemorrhage (sICH) and 90-day mortality, for patients undergoing EVT <6 h, >6 h, and >7.3 h, were compared. RESULTS: A total of 355 patients underwent EVT for LVO AIS at our institution during the review period, with 74 (21%) patients treated ≥6 h from symptom onset. Successful recanalization was achieved in 285 (80%) patients, with 228 (81%) achieving a mTICI ≥2b in the <6 h group, and 57 (77%) in the >6 h group (P = 0.429). Ninety-day functional independence (mRS 0-2) was achieved in 162 (46%) patients, with 130 (46%) achieving a mRS of 0-2 in the <6 h group, and 32 (43%) in the >6 h group (P = 0.643). No significant differences were found in rates of sICH or 90-day mortality. No significant differences in functional independence, recanalization rates, sICH or mortality were identified in patients treated with EVT >7.3 h compared to <7.3 h. CONCLUSIONS: In appropriately selected patients, EVT >6 h was associated with comparable outcomes to those treated <6 h. These data support a physiological approach to patient selection.


Assuntos
Isquemia Encefálica/terapia , Procedimentos Endovasculares , Acidente Vascular Cerebral/terapia , Trombectomia , Idoso , Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/mortalidade , Procedimentos Endovasculares/métodos , Procedimentos Endovasculares/mortalidade , Feminino , Humanos , Irlanda , Masculino , Pessoa de Meia-Idade , Seleção de Pacientes , Estudos Retrospectivos , Fatores de Risco , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/mortalidade , Trombectomia/métodos , Fatores de Tempo , Resultado do Tratamento
10.
J Stroke Cerebrovasc Dis ; 25(2): e9-11, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26698640

RESUMO

Ischemic stroke is a major public health problem worldwide, considered as the third most costly health condition in developed countries, with urgent reperfusion remaining the paramount goal for its treatment. In line with the results of recent randomized control trials, the introduction of stent retrievers was a major advancement in the treatment of stroke; however, interventionalists sometimes encounter thrombi not-retrievable by applying conventional techniques. In this article, we present a case treated by an innovative double-stent retrieval in Y-configuration that may potentially help other clinicians in similar situations.


Assuntos
Isquemia Encefálica/terapia , Procedimentos Endovasculares/métodos , Infarto da Artéria Cerebral Média/cirurgia , Stents , Acidente Vascular Cerebral/terapia , Idoso , Humanos , Masculino , Resultado do Tratamento
11.
Clin Radiol ; 70(12): 1408-13, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26385204

RESUMO

AIM: To report the experience of a regional stroke referral service with endovascular treatment for patients with acute ischaemic stroke (AIS) and large vessel occlusion. MATERIALS AND METHODS: A prospective review was undertaken of 93 consecutive cases receiving endovascular treatment for AIS over a 42-month period (January 2010 to June 2013). The National Institutes of Health Stroke Scale (NIHSS), location of large vessel occlusion, details of endovascular procedure, and degree of reperfusion achieved (Thrombolysis In Cerebral Infarction [TICI] score) were recorded. Mortality and functional outcome (modified Rankin Scale [mRS]) were measured at 90 days. RESULTS: The mean patient age was 62 years (range 26-87 years). The mean NIHSS at presentation was 16 (range 6-29). All patients had confirmed proximal large-artery occlusion on computed tomography (CT) angiography: 87 in the anterior circulation, six in the posterior circulation. Of the 93 patients treated, 64 (69%) received intravenous thrombolysis. Successful reperfusion (TICI grade 2a to 3) was achieved in 80 (86%) cases. There were 13 (14%) cases of failed vessel recanalisation (TICI grade 0). Good functional outcome (mRS ≤2) was achieved in 51 (55%) cases. The 90-day mortality was 20 (22%) cases. Fifty-seven (61%) cases were transferred from outside centres. There was no significant increase in morbidity or mortality for transferred patients. CONCLUSION: Successful endovascular recanalisation can result in good functional outcomes for patients with AIS and large vessel occlusion. Our interventional neuroradiology service provides endovascular treatment as part of a regional stroke service without increase in morbidity or mortality for patients transferred from outside institutions.


Assuntos
Arteriopatias Oclusivas/cirurgia , Isquemia Encefálica/cirurgia , Procedimentos Endovasculares , Stents , Acidente Vascular Cerebral/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Arteriopatias Oclusivas/complicações , Arteriopatias Oclusivas/diagnóstico por imagem , Isquemia Encefálica/complicações , Isquemia Encefálica/diagnóstico por imagem , Angiografia Cerebral , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Resultado do Tratamento
12.
Proc Biol Sci ; 281(1783): 20140248, 2014 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-24718762

RESUMO

Fitting models with Bayesian likelihood-based parameter inference is becoming increasingly important in infectious disease epidemiology. Detailed datasets present the opportunity to identify subsets of these data that capture important characteristics of the underlying epidemiology. One such dataset describes the epidemic of bovine tuberculosis (bTB) in British cattle, which is also an important exemplar of a disease with a wildlife reservoir (the Eurasian badger). Here, we evaluate a set of nested dynamic models of bTB transmission, including individual- and herd-level transmission heterogeneity and assuming minimal prior knowledge of the transmission and diagnostic test parameters. We performed a likelihood-based bootstrapping operation on the model to infer parameters based only on the recorded numbers of cattle testing positive for bTB at the start of each herd outbreak considering high- and low-risk areas separately. Models without herd heterogeneity are preferred in both areas though there is some evidence for super-spreading cattle. Similar to previous studies, we found low test sensitivities and high within-herd basic reproduction numbers (R0), suggesting that there may be many unobserved infections in cattle, even though the current testing regime is sufficient to control within-herd epidemics in most cases. Compared with other, more data-heavy approaches, the summary data used in our approach are easily collected, making our approach attractive for other systems.


Assuntos
Surtos de Doenças/veterinária , Modelos Teóricos , Tuberculose Bovina/epidemiologia , Tuberculose Bovina/transmissão , Animais , Número Básico de Reprodução , Teorema de Bayes , Bovinos , Funções Verossimilhança , Reino Unido/epidemiologia
13.
Genes Brain Behav ; 13(4): 418-29, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24571439

RESUMO

Specific language impairment (SLI) is a neurodevelopmental disorder that affects linguistic abilities when development is otherwise normal. We report the results of a genome-wide association study of SLI which included parent-of-origin effects and child genotype effects and used 278 families of language-impaired children. The child genotype effects analysis did not identify significant associations. We found genome-wide significant paternal parent-of-origin effects on chromosome 14q12 (P = 3.74 × 10(-8)) and suggestive maternal parent-of-origin effects on chromosome 5p13 (P = 1.16 × 10(-7)). A subsequent targeted association of six single-nucleotide-polymorphisms (SNPs) on chromosome 5 in 313 language-impaired individuals and their mothers from the ALSPAC cohort replicated the maternal effects, albeit in the opposite direction (P = 0.001); as fathers' genotypes were not available in the ALSPAC study, the replication analysis did not include paternal parent-of-origin effects. The paternally-associated SNP on chromosome 14 yields a non-synonymous coding change within the NOP9 gene. This gene encodes an RNA-binding protein that has been reported to be significantly dysregulated in individuals with schizophrenia. The region of maternal association on chromosome 5 falls between the PTGER4 and DAB2 genes, in a region previously implicated in autism and ADHD. The top SNP in this association locus is a potential expression QTL of ARHGEF19 (also called WGEF) on chromosome 1. Members of this protein family have been implicated in intellectual disability. In summary, this study implicates parent-of-origin effects in language impairment, and adds an interesting new dimension to the emerging picture of shared genetic etiology across various neurodevelopmental disorders.


Assuntos
Apraxias/genética , Impressão Genômica , Genótipo , Proteínas de Ligação a RNA/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Adulto , Proteínas Reguladoras de Apoptose , Criança , Cromossomos Humanos/genética , Feminino , Estudo de Associação Genômica Ampla , Fatores de Troca do Nucleotídeo Guanina/genética , Humanos , Masculino , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Proteínas de Ligação a RNA/genética , Receptores de Prostaglandina E Subtipo EP4/genética , Proteínas Supressoras de Tumor/genética
14.
Case Rep Vasc Med ; 2013: 121696, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23509662

RESUMO

Internal carotid artery dissection (ICAD) is an important cause of acute ischemic stroke in younger patients. Potential acute treatments include anticoagulation, intravenous thrombolysis (IVT), and endovascular thrombectomy (ET). We report a case where the use of IVT followed by ET resulted in a good clinical outcome in a patient with tandem internal carotid and middle cerebral artery occlusion following ICAD.

15.
Epidemiol Infect ; 141(2): 314-23, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22717109

RESUMO

Due to its substantially lower prevalence of bovine tuberculosis (bTB) relative to other areas of Great Britain, Scotland was designated as an officially (bovine) TB-free region in 2009. This paper investigates resultant possibilities for reducing surveillance by developing risk-based alternatives to current 4-year testing of eligible herds. A model of freedom of infection was used to develop strategies that specifically tested herds that are at risk of infection but would probably not be identified by slaughterhouse meat inspection. The performance of current testing is mimicked by testing all herds that slaughter fewer than 25% of their total stock per year and regularly import animals from high-incidence areas of England and Wales or from Ireland. This system offers a cost reduction by requiring 25% fewer herd and animal tests and 25% fewer false positives.


Assuntos
Matadouros/normas , Monitoramento Epidemiológico/veterinária , Testes Imunológicos/veterinária , Mycobacterium bovis/patogenicidade , Tuberculose Bovina/epidemiologia , Animais , Bovinos , Testes Imunológicos/economia , Testes Imunológicos/métodos , Incidência , Prevalência , Risco , Escócia/epidemiologia
16.
Nano Lett ; 12(2): 1045-52, 2012 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-22236130

RESUMO

The discovery of a flat two-dimensional crystal known as graphene has contradicted Landau-Peierls-Mermin-Wagner arguments that there is no stable flat form of such crystals. Here, we show that the "flat" shape of graphene arises due to a microscopic buckling at the smallest possible interatomic scale. We show that the graphene, silicene, and other two-dimensional crystals are stable due to transverse short-range displacements of appropriate atoms. The distortions are small and form various patterns, which we describe in a framework of Ising model with competing interactions. We show that when temperature decreases, two transitions, disorder into order and order into disorder, arise. The ordered state has a form of stripes where carbon atoms are shifted regularly with respect to the plane. The flat graphene, silicene, or germanene planes look like a microscopic "washboard" with the wavelength of about couple of interatomic spacing of appropriate sublattices, which for graphene is about 1.8-3.6 Å. At lower temperatures, the ordered state transforms into a glass. Because of up-down asymmetry in buckled graphene, silicene and other two-dimensional crystals deposited on substrate, a minibandgap may arise. We derive a criterion for the minigap formation and show how it is related to the buckling and to the graphene-substrate interaction. Because of the bandgap, there may arise new phenomena and in particular a rectification of ac current induced by microwave or infrared radiation. We show that the amplitude of direct current arising at wave mixing of two harmonics of microwave electromagnetic radiation is huge. Moreover, we predict the existence of miniexcitons and a new type of fermionic minipolaritons whose behavior can be controlled by the microwave and terahertz radiation.


Assuntos
Germânio/química , Grafite/química , Silício/química , Cristalização , Modelos Moleculares , Semicondutores
17.
Child Care Health Dev ; 38(2): 287-91, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21392056

RESUMO

BACKGROUND: Drooling is common in children with disordered oral-motor control. There is little evidence about the comparative effectiveness of different interventions used to reduce the impact of drooling. Anecdotal reports suggest clinicians' management of drooling varies widely. The aims of this survey were to establish which drooling interventions are currently used, how their effectiveness is monitored and how frequently adverse effects are reported. METHODS: 151 UK paediatricians completed a questionnaire about their management of drooling. RESULTS: Paediatricians saw one new child with problematic drooling and three follow-up children per month. The most common prescribing pattern was hyoscine first line (84.7%) followed by glycopyrronium bromide second line. The reported rate of adverse effects of medications was lower than expected (median 10% for hyoscine). Very few paediatricians used standardized methods of measuring the medication's effectiveness or adverse effects. CONCLUSION: Paediatricians regularly see small numbers of children with problematic drooling. Their clinical management of drooling varies; this is most likely because of a lack of evidence about the most effective approach. Comparative trials of interventions and the development of evidence-based clinical guidelines would improve the management of children's drooling.


Assuntos
Gerenciamento Clínico , Sialorreia/tratamento farmacológico , Adolescente , Criança , Pré-Escolar , Feminino , Seguimentos , Glicopirrolato/uso terapêutico , Humanos , Lactente , Recém-Nascido , Masculino , Doenças do Sistema Nervoso/complicações , Pediatria , Escopolamina/uso terapêutico , Inquéritos e Questionários
20.
AJNR Am J Neuroradiol ; 31(10): 1917-22, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20705703

RESUMO

BACKGROUND AND PURPOSE: The HydroCoil is an expansile hydrogel coil designed to produce a greater degree of volumetric packing within cerebral aneurysms when compared with bare platinum coils. This increased packing is, in turn, believed to decrease the risk of recurrence within aneurysms and hence the risk of their rupture in the long term. The aim of this work was to assess whether the use of HydroCoils and the proportion of HydroCoil used have any influence on the subsequent occlusion and recurrence rates of treated aneurysms. MATERIALS AND METHODS: A retrospective study was performed of 328 patients during 5 years at a single institution. The initial angiographic and follow-up angiographic occlusion rates were recorded as were any procedural complications. The proportion of HydroCoil used was described as the relative amount of HydroCoil length to the total coil length used during an aneurysm treatment, thus forming 4 groups: 0%-19%, 20%-49%, 50%-69%, 70%-100%, and the subgroups with 100%. RESULTS: Two hundred seventy patients had angiographic follow-up during an average of 13 months. The overall risk of permanent neurologic deficit and death was 3%. The rate of complete occlusion was 31% immediately postcoiling and 64.8% on follow-up. At the latest follow-up, 25.6% had residual necks and 9.6% had residual aneurysms. There was a statistically significant trend for HydroCoils to produce greater occlusion rates on follow-up when >70% HydroCoil was used (P = .025). The overall rate of recurrence for all aneurysms as a group was 15.5%. The retreatment rate was 6.6%. There has been 1 rebleed in the 328 patients. CONCLUSIONS: The overall results following the use of HydroCoils to occlude aneurysms compare well with those in other reported series. HydroCoils do produce a statistically significantly greater rate of occlusion when >70% of total aneurysm coil length is HydroCoil compared with coiling with <20% HydroCoil. There was no significant difference, however, in the recurrence or retreatment rate when comparing these groups.


Assuntos
Embolização Terapêutica , Hidrogel de Polietilenoglicol-Dimetacrilato , Aneurisma Intracraniano/terapia , Angiografia Cerebral , Embolização Terapêutica/efeitos adversos , Embolização Terapêutica/instrumentação , Embolização Terapêutica/métodos , Feminino , Seguimentos , Humanos , Hidrocefalia/epidemiologia , Aneurisma Intracraniano/diagnóstico por imagem , Aneurisma Intracraniano/epidemiologia , Masculino , Pessoa de Meia-Idade , Retratamento/estatística & dados numéricos , Estudos Retrospectivos , Fatores de Risco , Prevenção Secundária
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...