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1.
BMC Public Health ; 18(1): 866, 2018 07 12.
Artículo en Inglés | MEDLINE | ID: mdl-30001193

RESUMEN

It has been highlighted that in the original article [1] there is a typesetting mistake in the name of I. Fakoya. This was incorrectly captured as F. Fakoya. This correction article clarifies the correct name of the author.

2.
BMC Public Health ; 18(1): 499, 2018 04 13.
Artículo en Inglés | MEDLINE | ID: mdl-29653536

RESUMEN

BACKGROUND: Increasing routine HIV testing among key populations is a public health imperative, so improving access to acceptable testing options for those in need is a priority. Despite increasing targeted distribution and uptake of HIV self-sampling kits (SSKs) among men who have sex with men in the UK, little is known about why targeted SSK interventions for black African users are not as wide-spread or well-used. This paper addresses this key gap, offering insight into why some groups may be less likely than others to adopt certain types of SSK interventions in particular contexts. These data were collected during the development phase of a larger study to explore the feasibility and acceptability of targeted distribution of SSKs to black African people. METHODS: We undertook 6 focus groups with members of the public who self-identified as black African (n = 48), 6 groups with specialists providing HIV and social services to black African people (n = 53), and interviews with HIV specialist consultants and policy-makers (n = 9). Framework analysis was undertaken, using inductive and deductive analysis to develop and check themes. RESULTS: We found three valuable components of targeted SSK interventions for this population: the use of settings and technologies that increase choice and autonomy; targeted offers of HIV testing that preserve privacy and do not exacerbate HIV stigma; and ensuring that the specific kit being used (in this case, the TINY vial) is perceived as simple and reliable. CONCLUSIONS: This unique and rigorous research offers insights into participants' views on SSK interventions, offering key considerations when targeting this population.. Given the plethora of HIV testing options, our work demonstrates that those commissioning and delivering SSK interventions will need to clarify (for users and providers) how each kit type and intervention design adds value. Most significantly, these findings demonstrate that without a strong locus of control over their own circumstances and personal information, black African people are less likely to feel that they can pursue an HIV test that is safe and secure. Thus, where profound social inequalities persist, so will inequalities in HIV testing uptake - by any means.


Asunto(s)
Población Negra/psicología , Infecciones por VIH/etnología , Tamizaje Masivo/métodos , Aceptación de la Atención de Salud/etnología , Autocuidado , Manejo de Especímenes/métodos , Adolescente , Adulto , Población Negra/estadística & datos numéricos , Estudios de Factibilidad , Femenino , Grupos Focales , Infecciones por VIH/diagnóstico , Humanos , Masculino , Tamizaje Masivo/estadística & datos numéricos , Persona de Mediana Edad , Investigación Cualitativa , Reino Unido , Adulto Joven
3.
Br J Surg ; 103(7): 830-8, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27171027

RESUMEN

BACKGROUND: Completeness of excision is the most important factor influencing local recurrence after breast-conserving surgery (BCS). The aim of this case-control study was to determine factors influencing incomplete excision in patients undergoing BCS. METHODS: Women with invasive breast cancer treated by BCS between 1 June 2008 and 31 December 2009 were identified from a prospectively collected database in the Edinburgh Breast Unit. The maximum size of the tumour, measured microscopically, was compared with the size estimated before operation by mammography and ultrasound imaging. A multivariable analysis was performed to investigate factors associated with incomplete excision. RESULTS: The cohort comprised 311 women, of whom 193 (62·1 per cent) had a complete (CE group) and 118 (40·7 per cent) an incomplete (IE group) excision. Mammography underestimated tumour size in 75·0 per cent of the IE group compared with 40·7 per cent of the CE group (P < 0·001). Ultrasound imaging underestimated tumour size in 82·5 per cent of the IE group compared with 56·5 per cent of the CE group (P < 0·001). The risk of an incomplete excision was greater when mammography or ultrasonography underestimated pathological size: odds ratio (OR) 4·38 (95 per cent c.i. 2·59 to 7·41; P < 0·001) for mammography, and OR 3·64 (2·03 to 6·54; P < 0·001) for ultrasound imaging. For every 1-mm underestimation of size by mammography and ultrasonography, the relative odds of incomplete excision rose by 10 and 14 per cent respectively. CONCLUSION: Underestimation of tumour size by current imaging techniques is a major factor associated with incomplete excision in women undergoing BCS.


Asunto(s)
Neoplasias de la Mama/diagnóstico por imagen , Neoplasias de la Mama/cirugía , Mastectomía Segmentaria , Neoplasias de la Mama/patología , Carcinoma Intraductal no Infiltrante/diagnóstico por imagen , Carcinoma Intraductal no Infiltrante/patología , Carcinoma Intraductal no Infiltrante/cirugía , Estudios de Casos y Controles , Femenino , Humanos , Mamografía , Márgenes de Escisión , Persona de Mediana Edad , Análisis Multivariante , Neoplasia Residual , Ultrasonografía Mamaria
4.
Psychol Med ; 46(4): 829-40, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26541510

RESUMEN

BACKGROUND: There is evidence of executive function impairment in obsessive compulsive disorder (OCD) that potentially contributes to symptom development and maintenance. Nevertheless, the precise nature of these executive impairments and their neural basis remains to be defined. METHOD: We compared stopping and shifting, two key executive functions previously implicated in OCD, in the same task using functional magnetic resonance imaging, in patients with virtually no co-morbidities and age-, verbal IQ- and gender-matched healthy volunteers. The combined task allowed direct comparison of neural activity in stopping and shifting independent of patient sample characteristics and state variables such as arousal, learning, or current symptom expression. RESULTS: Both OCD patients and controls exhibited right inferior frontal cortex activation during stopping, and left inferior parietal cortex activation during shifting. However, widespread under-activation across frontal-parietal areas was found in OCD patients compared to controls for shifting but not stopping. Conservative, whole-brain analyses also indicated marked divergent abnormal activation in OCD in the caudate and thalamus for these two cognitive functions, with stopping-related over-activation contrasting with shift-related under-activation. CONCLUSIONS: OCD is associated with selective components of executive function, which engage similar common elements of cortico-striatal regions in different abnormal ways. The results implicate altered neural activation of subcortical origin in executive function abnormalities in OCD that are dependent on the precise cognitive and contextual requirements, informing current theories of symptom expression.


Asunto(s)
Encéfalo/fisiopatología , Función Ejecutiva/fisiología , Trastorno Obsesivo Compulsivo/fisiopatología , Adulto , Nivel de Alerta/fisiología , Estudios de Casos y Controles , Núcleo Caudado/fisiopatología , Cognición/fisiología , Lóbulo Frontal/fisiopatología , Neuroimagen Funcional , Humanos , Imagen por Resonancia Magnética , Persona de Mediana Edad , Neostriado/fisiopatología , Lóbulo Parietal/fisiopatología , Análisis y Desempeño de Tareas , Tálamo/fisiopatología
5.
Opt Express ; 21(25): 30148-55, 2013 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-24514593

RESUMEN

We demonstrate the use of surface acoustic wave nebulization (SAWN) to load optical traps. We show that the droplets sizes produced can be tuned by altering the RF frequency applied to the devices, which leads to more control over the sizes of trapped particles. Typically the size distribution of the liquid aerosols delivered using SAWN is smaller than via a standard commercial nebulization device. The ability to trap a range of liquids or small solid particles, not readily accessible using other ultrasonic devices, is also demonstrated both in optical tweezers and dual beam fiber traps.


Asunto(s)
Aerosoles/química , Pinzas Ópticas , Soluciones/química , Soluciones/efectos de la radiación , Sonicación/métodos , Ensayo de Materiales , Sonido
6.
Cogn Affect Behav Neurosci ; 10(4): 460-9, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21098807

RESUMEN

Regret and relief are complex emotional states associated with the counterfactual processing of nonobtained outcomes in a decision-making situation. In the "actor effect," a sense of agency and personal responsibility is thought to heighten these emotions. Using fMRI, we scanned volunteers (n = 22) as they played a task involving choices between two wheel-of-fortune gambles. We examined how neural responses to counterfactual outcomes were modulated by giving subjects the opportunity to change their minds, as a manipulation of personal responsibility. Satisfaction ratings to the outcomes were highly sensitive to the difference between the obtained and nonobtained outcome, and ratings following losses were lower on trials with the opportunity to change one's mind. Outcome-related activity in the striatum and orbitofrontal cortex was positively related to the satisfaction ratings. The striatal response was modulated by the agency manipulation: Following losses, the striatal signal was significantly lower when the subject had the opportunity to change his/her mind. These results support the involvement of frontostriatal mechanisms in counterfactual thinking and highlight the sensitivity of the striatum to the effects of personal responsibility.


Asunto(s)
Cuerpo Estriado/fisiología , Toma de Decisiones/fisiología , Emociones/fisiología , Relaciones Interpersonales , Adulto , Anciano , Análisis de Varianza , Mapeo Encefálico , Cuerpo Estriado/irrigación sanguínea , Femenino , Lateralidad Funcional , Juego de Azar , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Oxígeno/sangre , Adulto Joven
7.
Sex Transm Infect ; 84(2): 92-3, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17971372

RESUMEN

OBJECTIVE: To consider the extent to which those presenting for post-exposure prophylaxis (PEP) after sexual risk had been encouraged to do so by their PEP-aware partners with (diagnosed) HIV. METHOD: Thirty men who had completed the 2005 UK Gay Men's Sex Survey who said they had ever tried to get PEP took part in a 30 minute telephone interview. RESULTS: Fifteen men in the sample described a sexual exposure incident where they had knowledge that their partner was diagnosed with having HIV. Of these, only five knew about their partner's HIV diagnosis prior to sexual contact. The remaining 10 sought PEP because their sexual partner revealed his positive status following potential sexual exposure. CONCLUSION: Our analysis revealed that word of mouth from friends, sexual partners and health professionals played a key role in men's knowledge about the existence of PEP. It is important for HIV and sexual health specialists to ensure that PEP information is not only targeted at those who are tested negative for HIV or are untested but also to people with diagnosed HIV.


Asunto(s)
Infecciones por VIH/prevención & control , Conocimientos, Actitudes y Práctica en Salud , Parejas Sexuales , Comunicación , Revelación , Infecciones por VIH/psicología , Homosexualidad Masculina , Humanos , Masculino , Aceptación de la Atención de Salud/estadística & datos numéricos , Educación del Paciente como Asunto , Sexo Inseguro/prevención & control , Sexo Inseguro/psicología
8.
Int J STD AIDS ; 17(5): 315-8, 2006 May.
Artículo en Inglés | MEDLINE | ID: mdl-16643681

RESUMEN

This paper presents an analysis of responses to the first criminal convictions for HIV transmission in England and Wales within a sample of people living with HIV. These findings represent an important contribution to the development of well-informed prosecution policy. The responses were collected during 20 focused group discussions with a community and web-recruited sample of heterosexual African men and women, and gay and bisexual men (n = 125) living with diagnosed HIV in London, Manchester and Brighton. The vast majority (90%) of comments made were critical of the implementation and impact of criminalization. In particular, respondents expressed concern about the way in which criminal convictions conflict with messages about shared responsibility for 'safer sex', and the extent to which such cases will exacerbate existing stigma and discrimination related to HIV. Most felt that the successes achieved by human rights approaches to HIV prevention, treatment, and care were placed under threat by the growing culture of blame encouraged by criminal prosecutions.


Asunto(s)
Derecho Penal , Infecciones por VIH/psicología , Infecciones por VIH/transmisión , Intención , Parejas Sexuales/psicología , Derecho Penal/legislación & jurisprudencia , Inglaterra , Femenino , Grupos Focales , Conocimientos, Actitudes y Práctica en Salud , Humanos , Londres , Masculino , Motivación , Asunción de Riesgos , Conducta Sexual , Gales
9.
Eur J Surg Oncol ; 42(5): 657-64, 2016 May.
Artículo en Inglés | MEDLINE | ID: mdl-26944365

RESUMEN

PURPOSE: Debate continues on what is an adequate margin width to define a clear margin and whether there is a need to excise pectoral fascia or remove skin in breast conserving surgery. This study set out to provide answers to these questions. PATIENTS AND METHODS: 1411 patients with invasive breast cancer were treated by breast conserving surgery and post-operative whole breast radiotherapy from January 2000 to December 2005. Distance from each margin to any in situ or invasive cancer was measured and recorded. If full thickness of breast tissue was removed no re excision of anterior and posterior margins was performed even if disease was <1 mm from a margin. Patients ≤50 years of age and those with anterior or posterior margins <1 mm to invasive cancer had a radiation boost. Median follow-up time was 6.4 years. RESULTS: Local in breast tumour relapse (IBTR) occurred in 50 patients. The overall actuarial IBTR rate at 5 years was 2.2%. There was no difference in IBTR when comparing patients with radial margins of 1-5 mm or 5-10 mm. Anterior and posterior margins <1 mm or with ink on tumour cells were not associated with an increase in IBTR. CONCLUSION: There is no justification for radial margins of greater than 1 mm. If the anterior or posterior margin is <1 mm and full thickness of breast tissue has been removed, then re excision of these margins is unnecessary if boost radiotherapy is delivered.


Asunto(s)
Neoplasias de la Mama/patología , Neoplasias de la Mama/cirugía , Mastectomía Segmentaria/métodos , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias de la Mama/radioterapia , Terapia Combinada , Femenino , Humanos , Metástasis Linfática , Persona de Mediana Edad , Clasificación del Tumor , Invasividad Neoplásica , Recurrencia Local de Neoplasia , Tasa de Supervivencia , Resultado del Tratamiento
10.
Pharmacol Ther ; 66(2): 369-86, 1995 May.
Artículo en Inglés | MEDLINE | ID: mdl-7667402

RESUMEN

The outcome of surgery in the elderly depends on the skill of the surgeon and the expertise of the anaesthetist caring for the patient. This anaesthetic proficiency depends initially on the application of the detailed knowledge of the drugs used during anaesthesia, and on the understanding of the way changes in the elderly patients' physiology with ageing affects both kinetic and dynamic facets of pharmacology. However, the very diversity of the elderly population makes their precise response to drugs unpredictable, and, therefore, clear, unequivocal guidance on practice is limited. The important changes in both physiology and pharmacokinetics with ageing are discussed before covering the specific drugs used in current anaesthetic practice in the United Kingdom. This review covers the drugs used primary for the induction and maintenance of anaesthesia, and only covers related fields where there are changes in recent practice that raise issues of importance during surgery. This review, therefore, deals mainly with the anaesthetic vapours and intravenous drugs, and with neuromuscular blocking agents. The restriction of space and the enormity of the subject demand that the areas covered in this review are solely limited to the major classes of drugs used routinely in general anaesthetic practice in the United Kingdom. The detailed pharmacokinetics and pharmacodynamics of drugs also used in the post-operative period, such as the wide variety of opiates, and of drugs mainly used in general medical practice, but occasionally used as premedicants or supplements during anaesthesia, have been monitored only in passing.


Asunto(s)
Envejecimiento/metabolismo , Anestésicos/farmacología , Factores de Edad , Anciano , Anestésicos/metabolismo , Anestésicos/farmacocinética , Anestésicos Generales/metabolismo , Anestésicos Generales/farmacocinética , Anestésicos Generales/farmacología , Anestésicos por Inhalación/farmacología , Anestésicos Intravenosos/farmacología , Humanos , Persona de Mediana Edad , Bloqueantes Neuromusculares/farmacología
11.
Chem Biol ; 2(7): 483-7, 1995 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-9383450

RESUMEN

BACKGROUND: Medicinal chemistry traditionally requires the identification of biologically active molecules by synthesizing and screening each purified substrate. Further progress in drug discovery then requires definition of the structure-activity relationship of the lead compound. More recently, combinatorial chemistry has emerged as a way to examine structure-activity relationships by screening a large mixture of compounds synthesized in a predictably random manner, without the labor-intensive costs of molecular isolation and purification. We set out to use this approach to examine the structural requirements for peptide binding to serotonin and dopamine transporters. RESULTS: We screened a tripeptide cassette library for serotonin and dopamine reuptake inhibition using cloned transporter assay systems. The method has afforded a number of tripeptide pharmacophores with inhibitory IC50 values ranging from 10 microM to < 1 microM in the dopamine and serotonin reuptake systems. The conformation of one of these tripeptides, N-acetyl-D-Trp-L-Phe-D-Lys-CONH2 (which inhibits serotonin uptake with an IC50 of 10 microM) was compared to that of the serotonin uptake inhibitor s-fluoxetine, and was shown to be more similar in conformation to fluoxetine than was an analogous tripeptide containing L-Lys (IC50 > 50 microM). CONCLUSIONS: We have identified five tripeptides with inhibitory IC50 values of < 10 microM in the serotonin reuptake system. One tripeptide was predicted to have pharmacophore features similar to that of fluoxetine, a selective and potent non-peptide serotonin reuptake inhibitor. Our results suggest that tripeptides derived from combinatorial libraries will help to define the important structural elements of pharmacophores.


Asunto(s)
Diseño de Fármacos , Oligopéptidos/química , Inhibidores Selectivos de la Recaptación de Serotonina/química , Animales , Inhibidores de Captación de Dopamina/química , Inhibidores de Captación de Dopamina/farmacología , Fluoxetina/química , Fluoxetina/farmacología , Modelos Moleculares , Conformación Molecular , Oligopéptidos/síntesis química , Oligopéptidos/farmacología , Ratas , Inhibidores Selectivos de la Recaptación de Serotonina/síntesis química , Inhibidores Selectivos de la Recaptación de Serotonina/farmacología , Relación Estructura-Actividad , Células Tumorales Cultivadas
12.
Drugs ; 58(3): 453-67, 1999 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-10493273

RESUMEN

General anaesthesia has become, thanks to recently developed drugs, monitoring devices and delivery systems, a very well tolerated method of making the great surgical opportunities of the last few years available to all ages of patient. With a balanced and rational use of drug profiles, general anaesthesia allows even frail and very ill patients a margin of tolerability inconceivable just a few years ago. For the vast majority of patients, the risk from the general anaesthetic technique is so small it can be considered negligible. However, the majority of general anaesthetic drugs are both highly potent and very toxic, with many of the volatile agents still having a therapeutic ratio of about 4:1. The anaesthetic staff have to continually upgrade their skills and knowledge to ensure that harm does not result. It is, however, reasonable to offer some practical guidelines from the current literature on when to choose a general anaesthetic technique, either alone or with a regional local anaesthetic method, and when to avoid loss of consciousness. The complications expected from the use of general anaesthesia are reviewed, and the basis for these complications investigated. The currently available drugs and their place in anaesthetic practice are also assessed. Recent developments in the area of total intravenous anaesthesia and monitoring for potential awareness using bispectral analysis suggest that this technique should now be included in the choice of anaesthetic. Recommendations are made on both the selection of the technique, and the appropriate agents for a given group of patients.


Asunto(s)
Anestesia General/efectos adversos , Anestesia General/normas , Anestésicos Generales/uso terapéutico , Factores de Edad , Anestesia General/clasificación , Anestesia General/métodos , Ensayos Clínicos como Asunto , Humanos , Participación del Paciente , Guías de Práctica Clínica como Asunto
13.
Cochrane Database Syst Rev ; (3): CD003320, 2002.
Artículo en Inglés | MEDLINE | ID: mdl-12137688

RESUMEN

BACKGROUND: Fracture of the distal radius is a common clinical problem, particularly in older white women with osteoporosis. Anaesthesia is usually provided during manipulation of displaced fractures or during surgical treatment. OBJECTIVES: To examine the evidence for the relative effectiveness of the main methods of anaesthesia (haematoma block, intravenous regional anaesthesia (IVRA), regional nerve blocks, sedation and general anaesthesia) as well as associated physical techniques and drug adjuncts used during the management of distal radial fractures in adults. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group specialised register (January 2002), the Cochrane Controlled Trials Register (The Cochrane Library Issue 4, 2001), MEDLINE (1966 to October 2001), EMBASE (1988 to 2001 Week 48), Current Controlled Trials (December 2001) and reference lists of articles. SELECTION CRITERIA: Randomised or quasi-randomised clinical trials evaluating relevant interventions for these injuries (see Objectives). We excluded pharmacological trials comparing drug dosages and, with one exception, different drugs in the same class. Also excluded were trials reporting only pharmacokinetic and/or physiological outcomes. DATA COLLECTION AND ANALYSIS: All trials meeting the selection criteria were independently assessed by the three reviewers for methodological quality. Data were extracted independently by two reviewers. Quantitative data are presented using relative risks or mean differences together with 95 per cent confidence limits. Only very limited pooling of results from comparable trials was possible. MAIN RESULTS: The 18 included studies involved at least 1200, mainly female and older, patients with fractures of the distal radius. All studies had serious methodological limitations, notably in the frequent failure to assess clinically important and longer-term outcomes. Five trials provided evidence that, when compared with haematoma block, IVRA provided better analgesia during fracture manipulation and enabled better and easier reduction of the fracture, with some indication of a reduced risk of later redislocation or need for re-reduction. In contrast, haematoma block was quicker and easier to perform and less resource intensive. There was inadequate evidence of relative effectiveness of different methods of anaesthesia only examined within single trials: nerve block versus haematoma block; intravenous sedation versus haematoma block; general anaesthesia versus haematoma block; general anaesthesia versus sedation; and general anaesthesia versus haematoma block and sedation. None of the three trials evaluating three different physical aspects of anaesthesia (injection site of, or extra tourniquet, for IVRA; and technique for brachial plexus block) provided conclusive evidence for the effectiveness and safety of the novel technique. Six trials examined the use of drug adjuncts. The addition of two different muscle relaxants and one analgesic was tested for IVRA; one sedative and hyaluronidase for haematoma block; and clonidine for brachial plexus block. All trials evaluating adjuncts failed to provide evidence on eventual clinical outcome. A seriously flawed study comparing bupivacaine with prilocaine for IVRA gave some insight on the potential confounding effects of treatment by different doctors on patient outcome. REVIEWER'S CONCLUSIONS: There was insufficient robust evidence from randomised trials to establish the relative effectiveness of different methods of anaesthesia, different associated physical techniques or the use of drug adjuncts in the treatment of distal radial fractures. There is, however, some indication that haematoma block provides poorer analgesia than IVRA, and can compromise reduction. Given the many unresolved questions over the management of these fractures, we suggest an integrated programme of research, which includes consideration of anaesthesia options, is the way forward.


Asunto(s)
Anestesia/métodos , Fracturas del Radio/terapia , Anciano , Femenino , Humanos , Masculino , Manipulación Ortopédica/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto
14.
Cranio ; 19(4): 230-6, 2001 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-11725846

RESUMEN

This study was conducted in order to compare the clinical freeway space measurements using three simple methods commonly used by dentists in their practices. The study was performed in 15 young healthy subjects with natural dentition and bilateral molar support. Artificial landmarks (adhesive tape) were placed on the more prominent parts of the nose and chin of each subject. Vertical dimension of occlusion (VDO) was measured in the intercuspal position. Postural vertical dimension (PVD) was measured in the following functional conditions: after swallowing saliva, after pronouncing the word "Mississippi", and in a relaxed postural mandibular position (RPMP). Then, the clinical freeway space value in each functional condition was obtained by subtracting VDO from PVD value. Significant differences among clinical freeway space values using three different methods were observed (ANOVA). A significantly higher clinical freeway space value was found using phonetics method than after swallowing and with the mandible in a relaxed postural position (Bonferroni multiple comparison test). No significant differences between swallowing and relaxed methods were found. These results seem to suggest that the measures of clinical freeway space depend upon the method used.


Asunto(s)
Dimensión Vertical , Adulto , Análisis de Varianza , Deglución/fisiología , Oclusión Dental , Oclusión Dental Céntrica , Femenino , Humanos , Masculino , Mandíbula/anatomía & histología , Mandíbula/fisiología , Fonética , Postura , Habla/fisiología , Estadística como Asunto
15.
J Neural Eng ; 11(5): 056017, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25188649

RESUMEN

OBJECTIVE: Laser surface modification of platinum (Pt) electrodes was investigated for use in neuroprosthetics. Surface modification was applied to increase the surface area of the electrode and improve its ability to transfer charge within safe electrochemical stimulation limits. APPROACH: Electrode arrays were laser micromachined to produce Pt electrodes with smooth surfaces, which were then modified with four laser patterning techniques to produce surface structures which were nanosecond patterned, square profile, triangular profile and roughened on the micron scale through structured laser interference patterning (SLIP). Improvements in charge transfer were shown through electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and biphasic stimulation at clinically relevant levels. A new method was investigated and validated which enabled the assessment of in vivo electrochemically safe charge injection limits. MAIN RESULTS: All of the modified surfaces provided electrical advantage over the smooth Pt. The SLIP surface provided the greatest benefit both in vitro and in vivo, and this surface was the only type which had injection limits above the threshold for neural stimulation, at a level shown to produce a response in the feline visual cortex when using an electrode array implanted in the suprachoroidal space of the eye. This surface was found to be stable when stimulated with more than 150 million clinically relevant pulses in physiological saline. SIGNIFICANCE: Critical to the assessment of implant devices is accurate determination of safe usage limits in an in vivo environment. Laser patterning, in particular SLIP, is a superior technique for improving the performance of implant electrodes without altering the interfacial electrode chemistry through coating. Future work will require chronic in vivo assessment of these electrode patterns.


Asunto(s)
Estimulación Eléctrica/instrumentación , Electrodos Implantados , Rayos Láser , Microelectrodos , Platino (Metal)/química , Platino (Metal)/efectos de la radiación , Corteza Visual/fisiología , Animales , Gatos , Análisis de Falla de Equipo , Diseño de Prótesis , Propiedades de Superficie
16.
J Neural Eng ; 10(1): 016009, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-23283391

RESUMEN

OBJECTIVE: Recent interest in the use of conducting polymers (CPs) for neural stimulation electrodes has been growing; however, concerns remain regarding the stability of coatings under stimulation conditions. These studies examine the factors of the CP and implant environment that affect coating stability. The CP poly(ethylene dioxythiophene) (PEDOT) is examined in comparison to platinum (Pt), to demonstrate the potential performance of these coatings in neuroprosthetic applications. APPROACH: PEDOT is coated on Pt microelectrode arrays and assessed in vitro for charge injection limit and long-term stability under stimulation in biologically relevant electrolytes. Physical and electrical stability of coatings following ethylene oxide (ETO) sterilization is established and efficacy of PEDOT as a visual prosthesis bioelectrode is assessed in the feline model. MAIN RESULTS: It was demonstrated that PEDOT reduced the potential excursion at a Pt electrode interface by 72% in biologically relevant solutions. The charge injection limit of PEDOT for material stability was found to be on average 30× larger than Pt when tested in physiological saline and 20× larger than Pt when tested in protein supplemented media. Additionally stability of the coating was confirmed electrically and morphologically following ETO processing. It was demonstrated that PEDOT-coated electrodes had lower potential excursions in vivo and electrically evoked potentials (EEPs) could be detected within the visual cortex. SIGNIFICANCE: These studies demonstrate that PEDOT can be produced as a stable electrode coating which can be sterilized and perform effectively and safely in neuroprosthetic applications. Furthermore these findings address the necessity for characterizing in vitro properties of electrodes in biologically relevant milieu which mimic the in vivo environment more closely.


Asunto(s)
Conductividad Eléctrica , Microelectrodos , Polímeros/química , Corteza Visual/fisiología , Prótesis Visuales/química , Animales , Gatos , Materiales Biocompatibles Revestidos/química , Microelectrodos/normas , Prótesis Visuales/normas
17.
Eye (Lond) ; 25(6): 694-703, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21455245

RESUMEN

The advent of a new technique that is considered much safer than previously established one leads to its rapid adoption. This usually leads to the identification of previously unreported complications of the new technique, and a re-assessment of its position in clinical care, which is precisely the state of play with the sub-Tenon's block. The sub-Tenon's block was introduced into the clinical practice in early 1990. A systematic recent search of subject headings such as complications of sub-Tenon's block, subtenon, orbital block, orbital block complications, and orbital anaesthesia was performed in Medline, EMBASE, and Cochrane database. Indeed there are complications of sub-Tenon's block published as case reports and the exact incidence of these complications is not known. Management and preventive measures of these complications are described. Although the sub-Tenon's block appears to be relatively safer than needle-based blocks but a proper prospective, randomized, double-blind controlled trial is essential for scientific proof that sub-Tenon's block is better than needle-based blocks.


Asunto(s)
Anestesia Local/métodos , Anestésicos Locales/efectos adversos , Bloqueo Nervioso/métodos , Procedimientos Quirúrgicos Oftalmológicos , Órbita , Anestesia Local/efectos adversos , Anestésicos Locales/administración & dosificación , Humanos , Bloqueo Nervioso/efectos adversos
18.
Int J STD AIDS ; 22(4): 190-3, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21515749

RESUMEN

This paper explores how men who have sex with men (MSM) with diagnosed HIV who engage in unprotected anal intercourse (UAI) perceive the potential risk of superinfection and how they respond to it. Semistructured interviews were carried out with 42 MSM recruited via community-based agencies throughout England and Wales. The interviews examined sexual risk taking and the ways in which men sought to manage the risks they perceived. All participants had heard of superinfection and one-third considered it a personal risk when they had UAI with men with the same sero-status. The risk of being superinfected with HIV was often situated among a number of other concerns that men felt they needed to manage when having sex. There was significant uncertainty about the likelihood of acquiring an additional strain of HIV, which was exacerbated by competing, and often conflicting, advice from a variety of expert sources. Men frequently drew upon lay and expert understandings of viral load and infectiousness to rationalize engagement in UAI with other diagnosed positive men. HIV health-care providers should seek to find consensus on how to discuss superinfection with MSM, taking account of the array of other physical and social risks associated with sex.


Asunto(s)
Infecciones por VIH/complicaciones , Infecciones por VIH/diagnóstico , Homosexualidad Masculina/psicología , Sobreinfección/psicología , Sexo Inseguro , Adolescente , Adulto , Canal Anal , Inglaterra , Humanos , Masculino , Persona de Mediana Edad , Asunción de Riesgos , Conducta Sexual , Parejas Sexuales , Gales , Adulto Joven
19.
Artículo en Inglés | MEDLINE | ID: mdl-22254389

RESUMEN

Retinal micro-electrode arrays (MEAs) for a visual prosthesis were fabricated by laser structuring of platinum (Pt) foil and liquid silicone rubber. A new design was created using a folding technique to create a multi-layered array from a single Pt sheet. This method allowed a reduction in both the electrode pitch, and the overall width of the array, while maintaining coplanar connection points for more stable interconnections to other components of the system. The design also included a section which could be rolled to create a cylindrical segment in order to minimise the size of the exit in the sclera after implantation. A picosecond mode-locked 532 nm laser system was investigated as a replacement for the nanosecond Q-switched 1064 nm laser currently in use. Trials showed that the ps system could produce high quality electrode tracks with a minimum pitch of 30 µm, less than 40% the pitch achievable with the ns laser. A method was investigated for the cutting of Pt foils without damaging the underlying silicone by laser machining to a depth just below the thickness of the foil. Initial samples showed promise with full penetration of the foil only occurring at cross points of the laser paths. The ps laser was also used to create roughened surfaces, in order to increase the electrochemical surface area of the electrodes. Surfaces were imaged using a scanning electron microscope, and compared to surfaces roughened with the ns laser. The ps laser was seen to offer a reduction in feature size, as well as an increase in control over the appearance of the electrode surface.


Asunto(s)
Electrodos Implantados , Materiales Manufacturados , Microelectrodos , Prótesis Visuales , Análisis de Falla de Equipo , Rayos Láser , Diseño de Prótesis , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
20.
Artículo en Inglés | MEDLINE | ID: mdl-21095836

RESUMEN

Conducting polymers (CPs) have the potential to provide superior neural interfaces to conventional metal electrodes by introducing more efficient charge transfer across the same geometric area. In this study the conducting polymer poly(ethylene dioxythiophene) (PEDOT) was coated on platinum (Pt) microelectrode arrays. The in vitro electrical characteristics were assessed during biphasic stimulation regimes applied between electrode pairs. It was demonstrated that PEDOT could reduce the potential excursion at a Pt electrode interface by an order of magnitude. The charge injection limit of PEDOT was found to be 15 x larger than Pt. Additionally, PEDOT coated electrodes were acutely implanted in the suprachoroidal space of a cat retina. It was demonstrated that PEDOT coated electrodes also had lower potential excursions in vivo and electrically evoked potentials (EEPs) could be detected within the vision cortex.


Asunto(s)
Microelectrodos , Polímeros , Prótesis Visuales , Animales , Gatos , Microscopía Electrónica de Rastreo
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