Plasmon resonances on metal tips: Understanding tip-enhanced Raman scattering

Calculations of the electric-field enhancements in the vicinity of an illuminated silver tip, modeled using a Drude dielectric response, have been performed using the finite difference time domain method. Tip-induced field enhancements, of application in "apertureless" Raman scanning near-field optical microscopy (SNOM), result from the resonant excitation of plasmons on the metal tip. The sharpness of the plasmon resonance spectrum and the highly localized nature of these modes impose conditions to better exploit tip plasmons in tip-enhanced apertureless SNOM. The effect of tip-to-substrate separation and polarization on the resolution and enhancement are analyzed, with emphasis on the different field components parallel and perpendicular to the substrate.

Repression of interleukin-5 transcription by the glucocorticoid receptor targets GATA3 signaling and involves histone deacetylase recruitment

Glucocorticoids are the mainstay of asthma therapy and mediate the repression of a number of cytokine genes, such as Interleukin (IL)-4, -5, -13, and granulocyte macrophage colony-stimulating factor (GM-CSF), which are central to the pathogenesis of asthmatic airway inflammation. The glucocorticoid receptor (GR) mediates repression by a number of diverse mechanisms. We have previously suggested that one such repressive activity is by direct binding of GR to elements within the GM-CSF enhancer that are recognized by the nuclear factor of activated T cells.activator protein 1 (NF-AT.AP-1) complex. We reasoned that, because many cytokine genes activated in asthma are transcriptionally regulated by the recruitment of this complex to DNA, their binding sites might provide a target for GR to mediate its repressive effects. Here, we show that transcriptional repression of the Interleukin-5 gene involves recruitment of GR to a DNA region located within the IL-5 proximal promoter, which is bound by NF-AT and AP-1 proteins. GR recruitment had a profound effect upon the activation capacity of GATA3, which has a binding site close to the NF-AT.AP-1 domain in both IL-5 and IL-13 promoters. Repression by GR involves co-repressor recruitment, because treatment of transfected cells with the deacetylase inhibitor trichostatin A caused a partial relief of repression. Additionally, repression could be augmented by co-transfection of cells with a histone deacetylase (HDAC1). These data suggest that the local recruitment of GR causes repression by inhibiting transcriptional activation by GATA3, a key tissue-specific determinant of expression of Th2 cytokines.

Resonant excitation of tip plasmons for tip-enhanced Raman SNOM

The conditions necessary for the optimisation of tip-enhanced scanning near-field optical microscopy have been determined. The Raman scattering efficiency can be enormously increased by enhancements in the local field amplitude, such as that which can occur in the vicinity of a metallic nanostructure. The field enhancement in the vicinity of a silver tip is investigated theoretically here using the finite difference time domain method. Field enhancements from electron oscillations on the tip are shown to display strong maxima at resonant illumination wavelengths and the nature of these enhancements at the substrate surface beneath the tip, both on and off resonance, has been calculated. The enhancement of the Raman signal on the surface decreases exponentially as the tip-substrate separation is increased and a peak Raman enhancement of 10(7) is theoretically achievable at a tip-surface separation of 2 nm. The resolution is also strongly related to the distance between the tip and the substrate surface narrowing to <7 nm, significantly smaller than the radius of curvature of the end of the tip.

First reported case of esophageal paraganglioma. A review of the literature of gastrointestinal tract paraganglioma including gangliocytic paraganglioma

Paraganglioma and the variant gangliocytic paraganglioma are rare gastrointestinal tumors. We present the first reported case of an esophageal paraganglioma and a review of the literature. From this review it seems that these tumors can occur at any age and usually present with acute or chronic bleeding with or without abdominal pain. The majority of reported cases originated in the foregut, most commonly the second part of the duodenum. Macroscopically the tumor may be pedunculated, sessile or ulcerated and have been described up to 10 cm in size. There are no reported cases of gut paragangliomas shown to be producing clinically significant amounts of catecholamines. The majority of reported tumors have been benign, only 7% malignant at presentation and all with lymph node metastases. One case developed bone metastases 3 years after excision and another recurred locally. There has been no benefit seen from radiotherapy or chemotherapy to date and it is recommended that all of these tumors are widely excised together with a lymph node resection if possible.

Near-field microscopy and lithography of light-emitting polymers

We describe the application of scanning near-field optical microscopy (SNOM) to the study of the photophysical and self-organization properties of thin films of blends of conjugated polymers, and also to the lateral nanoscale patterning of conjugated-polymer structures. Such thin-film plastic semiconductor nanostructures offer significant potential for use in opto-electronic devices. The implementation of SNOM we employ is the most established form in which a probe with a sub-wavelength aperture is scanned in close proximity to the sample surface. We consider the nature of the near-field optical distribution, which decays within the first ca. 100 nm of these semiconductor materials, and address the identification of topographic artefacts in near-field optical images. While the topographic information obtained simultaneously with optical data in any SNOM experiment enables an easy comparison with the higher-resolution tapping-mode atomic force microscopy, the spectroscopic contrast provided by fluorescence SNOM gives an unambiguous chemical identification of the different phases in a conjugated-polymer blend. Both fluorescence and photoconductivity SNOM indicate that intermixing of constituent polymers in a blend, or nanoscale phase separation, is responsible for the high efficiency of devices employing these materials as their active layer. We also demonstrate a scheme for nano-optical lithography with SNOM of conjugated-polymer structures, which has been employed successfully for the fabrication of poly(-phenylene vinylene) nanostructures with 160 nm feature sizes.

Ileitis due to Yersinia pseudotuberculosis in Crohn's disease

We present the case of a young woman with fulminating terminal ileitis due to Yersinia pseudotuberculosis, in whom Crohn's disease was subsequently diagnosed. Serological testing was prompted by radiological, macroscopic and histological changes which were atypical of Crohn's disease. We speculate that Y. pseudotuberculosis ileitis may occasionally produce an acute exacerbation of Crohn's disease, but that its occurrence may not be diagnosed if the atypical features are not recognised. In this case, the classical features of Y. pseudotuberculosis may have been modified by pre-existing Crohn's disease. We propose that, because of defects in mucosal barrier function and immunological function, patients with Crohn's may have increased susceptibility to infection by Yersinia sp.

Near-field microscopy: throwing light on the nanoworld

Optical microscopy with nanoscale resolution, beyond that which is possible with conventional diffraction-limited microscopy, may be achieved by scanning a nanoantenna in close proximity to a sample surface. This review will first aim to provide an overview of the basic principles of this technique of scanning near-field optical microscopy (SNOM), before moving on to consider the most widely implemented form of this microscopy, in which the sample is illuminated through a small aperture held less than 10 nm from the sample surface for optical imaging with a resolution of ca. 50 nm. As an example of the application of this microscopy, the results of SNOM measurements of light-emitting polymer nanostructures are presented. In particular, SNOM enables the unambiguous identification of the different phases present in the nanostructures, through the local analysis of the fluorescence from the polymers. The exciting new possibilities for high-resolution optical microscopy and spectroscopy promised by apertureless SNOM techniques are also considered. Apertureless SNOM may involve local scattering of light from a sample surface by a tip, local enhancement of an optical signal by a metal tip, or the use of a fluorescent molecule or nanoparticle attached to a tip as a local optical probe of a surface. These new optical nanoprobes offer the promise of optical microscopy with true nanometre spatial resolution.

Questionnaire survey on the use of computerisation in dental practices across the Thames Valley region

OBJECTIVES

To investigate the extent of and attitudes to computerisation in dental practices across the Thames Valley Strategic Health Authority Region.

DESIGN

Postal questionnaire survey.

RESULTS

A response rate of 88% was achieved. Most (77%) of the practices were using computerised systems or were planning to do so soon. The main reasons for not using computers were that computerisation was not currently necessary (56%), practice staff were reluctant to move to electronic systems (24%), or because computer systems were perceived as too expensive (19%). Computerised systems were used mainly for transmitting dental practice board data, or managing patient and financial records. Only 45% of practices had access to the internet and electronic mail (email). Forty-nine percent of practices thought that it was important to have access to email, 46% to the internet and 40% to NHSnet. Many practices requested training for staff in a variety of areas including managing databases and setting up web-sites.

CONCLUSIONS

Despite the advantages of using computerised systems, many dental practices were only using them to a limited extent. Training and follow-up support may encourage dental practice teams to develop more positive attitudes towards computerisation and encourage them to use computers more extensively in clinical practice.

Effectiveness of nursing interventions in people with personality disorders

BACKGROUND

Nurses usually provide care for people with personality disorders on a day-to-day basis. Consequently, it is important to establish how effective nursing interventions are for those with personality disorders, both in terms of general management and more specific therapeutic approaches. These are also issues of current political and professional debate. The crucial question, however, for planners, providers and commissioners of services is, What research evidence is there about effectiveness? There is also a need to determine what further research is necessary to evaluate programmes for managing or modifying behaviours.

AIM

The aim of this paper is to report on a systematic review of the literature on the effectiveness of nursing interventions in people with personality disorders, whether delivered by nurses alone or in combination with other health care professionals.

METHOD

The review was conducted according to the United Kingdom National Health Service Centre for Reviews and Dissemination guidelines. Literature was identified from electronic database searching, footnote chasing, hand searching of journals and contact with authors of studies. Narrative synthesis was undertaken in relation to study design, participants, and type of intervention.

FINDINGS

Eighteen separate studies were included in the review: four randomized controlled trials, four non-randomized controlled trials, seven before-and-after studies and three case studies.

CONCLUSIONS

There is a weak evidence-base for what constitutes effective nursing intervention with people with personality disorders. There is stronger evidence from mixed disciplines intervention studies than from nursing only intervention studies. Studies of interventions based on psychological approaches show greater improvements in outcomes than nursing management studies.

PHASE: a randomised, controlled trial of supervised self-help cognitive behavioural therapy in primary care

BACKGROUND

Common mental health problems account for up to 40% of all general practitioner (GP) consultations. Patients have limited access to evidence-based psychological therapies. Cognitive behavioural therapy self-help strategies offer one potential solution.

AIM

To determine differences in clinical outcome, patient satisfaction and costs, between a cognitive behavioural-based self-help package facilitated by practice nurses compared to ordinary care by GPs for mild to moderate anxiety and depression.

DESIGN OF STUDY

Randomised controlled trial.

SETTING

Seventeen primary healthcare teams.

METHOD

Patients presenting to their GP with mild to moderate anxiety and/or depression were recruited to the study and randomised to receive either a self-help intervention facilitated by practice nurses or ordinary care. The self-help intervention consisted of up to three appointments: two 1 week apart and a third 3 months later. There were no restrictions on ordinary care.

RESULTS

Intention-to-treat analysis showed that patients treated with practice nurse-supported cognitive behavioural therapy self-help attained similar clinical outcomes for similar costs and were more satisfied than patients treated by GPs with ordinary care. On-treatment analysis showed patients receiving the facilitated cognitive behavioural therapy self-help were more likely to be below clinical threshold at 1 month compared to the ordinary care group (odds ratio [OR] = 3.65, 95% confidence interval [CI] = 1.87 to 4.37). This difference was less well marked at 3 months (OR = 1.36, 95% CI = 0.52 to 3.56).

CONCLUSION

Facilitated cognitive behavioural self-help may provide a short-term cost-effective clinical benefit for patients with mild to moderate anxiety and depression. This has the potential to help primary care provide a choice of effective psychological as well as pharmacological treatments for mental health problems.

Smoking cessation interventions in the Oxford region: changes in dentists' attitudes and reported practices 1996-2001

OBJECTIVES

To investigate dentists' current beliefs and practices (2001) with respect to smoking cessation interventions and any changes that might have occurred since the last survey in 1996.

DESIGN

Postal questionnaire survey.

SETTING

General dental practitioners on the health authority lists of Berkshire, Buckinghamshire, Oxfordshire and Northamptonshire.

RESULTS

A response rate of 71% (696/984) was achieved. The majority of dentists (88.6%) thought that dentists should encourage their patients to stop smoking (increase of 6.3% since 1996; 95%CI 2.6, 10.2; p=0.001), although only 42.2% believed dentists were effective in this area (non-significant increase of 4.8% since 1996). Only 48.4% routinely recorded their patient's smoking status (increase of 30.3% since 1996; 95%CI 25.4, 34.9; p<0.001) and only 26.9% always discussed the habit with smokers (increase of 9.5% since 1996; 95%CI 5.1, 13.9; p<0.001). Less than 10% reported a good knowledge of NRT or Bupropion. About half of respondents requested more training and resources.

CONCLUSIONS

Dentists generally have positive attitudes to being involved in smoking cessation interventions, but although there are significant increases between 1996 and the current survey, few are active in this area. More training and resources may encourage dentists to be more proactive in helping their patients to stop smoking.

Agoraphobia: nurse therapist-facilitated self-help manual

BACKGROUND

Agoraphobia is a common and disabling mental health disorder. Substantial evidence supports the use of cognitive behaviour therapy (CBT), in particular the intervention termed exposure therapy, as the treatment of choice. However, although the evidence base for cognitive-behaviour therapy is extensive, the service delivery evidence base is poor, and alternative ways of delivering therapy are required if mental health services are to achieve standards set out by the National Service Framework in the United Kingdom.

AIM

The study had two aims: (1) to develop a self-help manual, which could be facilitated by a nurse trained in CBT, for clients suffering from agoraphobia and (2) to pilot the self-help manual and evaluate its effectiveness.

METHOD

The self-help manual was piloted with experienced nurses trained in CBT on three clinical sites for 10 weekly sessions of 30 minutes duration. A range of clinical outcome measures was administered by an independent assessor before and after treatment and at 1-month follow-up.

RESULTS

A total of 18 clients completed treatment and results showed improvement on all clinical measures; improvement was maintained at 1-month follow-up. Importantly, 89% of clients were clinically significantly improved at post-treatment assessment. Clients were satisfied with their treatment and the self-help manual, and therapists found facilitated self-help an acceptable way to deliver treatment.

CONCLUSION

Nurses can deliver effective support to patients using a self-help manual for agoraphobia. Although the results are promising, further work is required with larger numbers, longer follow-up and economic evaluation under controlled conditions. The work could also be adapted to different psychological conditions. Variation in the amount of specialist educational training is necessary to determine how many nurses are needed to support patients using self-help.

Critical realism: a way forward for evaluation research in nursing?

BACKGROUND

Critical realism is a relatively new philosophical perspective that combines a realist ontology with a relativist epistemology in subscribing to a form of "robust" relativism. The potential benefits of adopting a critical realist approach are considered in two areas of evaluation research: theory-driven programme evaluation and policy evaluation.

AIM

The aim of the paper is to identify the main features of critical realism and explore its potential as a philosophical framework in the field of evaluation research.

CONCLUSION

We argue that critical realism provides a coherent framework for evaluation research that is based on the understanding of causal mechanisms. This is particularly important for frontline services seeking to use evidence-based interventions, as interventions need to be properly understood if they are to be used effectively in the context of clinical practice. Critical realism can also add depth to policy analysis. However, there is a potential for critical realists to drift beyond the boundary that separates scientific knowledge from speculative theory when making recommendations about the best course of action to follow.

Investigation of extracellular amino acid release in children with severe head injury using microdialysis. A pilot study

Microdialysis has been used to investigate the pathophysiology of severe head injury in adults. No similar data exist, however, for children. As part of routine neuromonitoring, five children with severe, closed head injury (GCS < 8) were fitted with a microdialysis probe (CMA 70) at the time of intracranial pressure bolt insertion. Samples were collected at hourly intervals prior to analysis of amino acids by High Performance Liquid Chromatography. In contrast to adult patients, glutamate and aspartate did not correlate with structural amino acid levels and were inversely related to glutamine levels, suggesting that excitatory aminoacid release in children with severe head injury is likely to be an active process rather than an effect of indiscriminate cell destruction and that glutamate levels extracellularly may also depend on glutamate uptake and metabolism. The nitric oxide metabolite citrulline remained at similar levels in different patients throughout the monitoring period, indicating that nitric oxide metabolism may not follow the pattern of glutamate release. Our study is suggesting that amino acid release in severe head injury in children may not correspond to the recognised patterns from cell culture and animal studies and may also differ from that in adults.