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The poem "Honey Flies" by H. Lynnette Barr is presented. First line: it has me; Last line: when i am dead.

There are distinct challenges implicit to the development of minimally invasive endoscopic surgery for the eradication of early neoplasia in Barrett's oesophagus. Endoscopic resection and ablation of high-grade dysplasia and mucosal cancer offer alternative therapeutic options to those unsuitable or unwilling to contemplate radical surgical excision. It may also become the treatment of choice in the future. Technological developments enable the instantaneous and non-invasive diagnosis of microscopic tissue abnormalities in vivo. This is made possible by improving the level of information that can be obtained from the tissue. As well as the two-dimensional surface morphology image, which the traditional endoscope can view, we have used new techniques to enable structure at depth, using Optical Coherence Tomography, to be imaged in high resolution. Other advances, using Raman spectroscopy, enable the early endoscopic detection of biochemical and molecular changes in tissue that precede any changes in morphology, thus enabling earlier diagnosis of tissue abnormalities. This King James IV lecture details our recent work, to develop advanced imaging for the diagnosis of malignancy and pre-malignancy. After detection endoscopic photodynamic therapy and endoscopic mucosal resection can provide eradication of mucosal neoplasia. Following photodynamic therapy there was complete eradication of all high-grade dysplasia and intramucosal carcinoma in 40 of 42 patients with a maximum endoscopic follow-up period of 72 months. Following endoscopic resection of 95 patients, the mean survival for intramucosal adenocarcinoma and high-grade dysplasia was 40.6 and 60.8 months respectively. [ABSTRACT FROM AUTHOR]

The article presents information on endoscopic therapy for Barrett's Oesophagus. Barrett's oesophagus or columnar lined oesophagus is among the most intriguing of gastroenterological conditions. This is because of its pathogenesis, prevalence, association with reflux disease, male sex and, in particular, the potential for neoplastic degeneration to adenocarcinoma. The current and dramatic rise in the incidence of oesophageal adenocarcinoma is centred on Great Britain, over double that of the U.S.A. This epidemic is fairly localised and is not evident in Asia, where squamous cell cancer remains the predominant oesophageal malignancy. Large rises in incidence, up to 30% per year, have been seen in West European White men.

There is a strong association between symptomatic gastro-oesophageal reflux and oesophageal adenocarcinoma. With this in mind, the American College of Gastroenterology has recently revised its practice guidelines for the screening of patients with chronic gastro-oesophageal reflux disease (GERD) to identify those at risk of oesophageal adenocarcinoma, and recommends surveillance to identify curable oesophageal neoplasms in patients with established Barrett's oesophagus. Patients with chronic GERD symptoms, particularly those aged over 50 years, should undergo upper endoscopy. Patients found to have Barrett's oesophagus should be treated with acid suppression for GERD symptoms and then undergo regular surveillance endoscopy. Surveillance endoscopy every 3 years is recommended for those without dysplasia. For patients with verified low-grade dysplasia, yearly surveillance endoscopy is recommended. For those with focal high-grade dysplasia (defined as high-grade dysplastic changes involving fewer than five crypts), the condition may be followed with endoscopic surveillance performed at 3-month intervals. If there is verified, multifocal high-grade dysplasia, intervention (e.g. oesophagectomy) may be considered. Both observational and computer models suggest a benefit associated with screening and surveillance. Endoscopic screening and surveillance for Barrett's oesophagus compares favourably with mammography for the detection of breast cancer and other accepted medical practices. [ABSTRACT FROM AUTHOR]

A concise general dispersion relation is found to describe electron parametric instabilities driven by relativistically intense circularly polarized laser light in plasma. It is valid for densities from rarefied plasma up to overdense regions accessible by self-induced transparency due to the relativistic electron mass increase. In the form of a fourth order scalar difference equation, it describes stimulated harmonic generation as well as stimulated Raman scattering, the relativistic modulational and filamentation instabilities, and the two-plasmon decay. It is also related to analytic results for stimulated harmonic generation from rarefied plasma and to synchrotron radiation from single electrons. [ABSTRACT FROM AUTHOR]

Photodynamic therapy involves the activation of an exogeneously administered, or an endogenously gen-erated, photosensitizer with light to produce localized tissue destruction. It is an attractive, predominantly endosopic technique for the palliation of advanced upper gastrointestinal cancer and the eradication of early neoplastic and pre-neoplastic lesions. The nature of the biological response allowing safe healing and the exploitation of tissue threshold effects mean that adjacent tissue damage can be minimized. This review used a database of 368 papers. The nature of the photosensitizer is critical to the depth of tissue damage and the risk of adjacent tissue damage and stricture formation. The generation of protoporphyrin IX following administration of 5-aminolaevulinic acid has proved useful for the treatment of high-grade dysplasia in Barrett’s oesophagus. A double-blind randomized placebo controlled trial has confirmed that it is a safe and effective method for the ablation of low-grade dysplasia. The treatment of more advanced lesions requires exogeneously administered photo-sensitizers. However, recent data indicate that the neoplastic potential remains in some patients and continued follow-up is necessary. Photodynamic therapy can be used to eradicate early neoplasia and palliate advanced cancer, but caution is required before a definitive cure can be claimed. [ABSTRACT FROM AUTHOR]

In this report a complex Raman scattering event against a background of nonthermal ion coustic waves in an inhomogenous plasma is considered. The complex Raman process is a five-wave interaction in which three-wave stimulated Raman scattering (SRS) is accompanied by the decay of the Raman Langmuir wave into either a second Langmuir wave (LD) or a second scattered light wave (ED) and an ion acoustic wave. An extension of Stokes’ theory is used to obtain expressions for the gain in the Raman Langmuir and scattered waves. It is shown that only very modest levels of ion waves are needed to produce duce a significant effect on the net Raman convective gain which proves to be sensitive to the source levels of the amplifying waves. For LD the gain from the Raman Langmuir wave source is suppressed while that from the secondary Langmuir wave is enhanced such that the net gain is increased or decreased depending on which of the two sources is greater. When the source levels of both Langmuir waves are at thermal levels, opposing effects mean no net change in the gain factor irrespective of the ion acoustic wave amplitude. For ED the gain is invariably suppressed for any source distributions. Two possible regimes of an enhanced effect have been identified: exact sidescattering for ED and the supersonic point vicinity for LD(ED). The theory thus provides a possible explanation for a variety of the observed effects in the interplay between SRS and stimulated Brillouin scattering, both of concern in laser fusion schemes. [ABSTRACT FROM AUTHOR]

Photodynamic therapy is now a useful and practical option of the local treatment of gastrointestinal cancers. There is increasing screening and surveillance of patients at risk of oesophageal and gastric cancers. The early detection of disease is often unhelpful if an elderly or frail patient needs to be subjected to radical resectional surgery. Photodynamic therapy can eradicate and cure early mucosal disease following a single endoscopic treatment. If the disease is more advanced good local control and palliation is often possible. Overall, palliation can often be achieved using simpler methods which are highly effective and not associated with the problems of prolonged photosensitisation. It is rapidly becoming clear that the ideal indication is for the treatment of dysplastic lesions in the oesophagus associated with columnar-lined oesophagus (Barrett's oesophagus). In these circumstances a heterogeneous field change often with multifocal dysplasia or cancer can be widely eradicated. Similar areas of squamous dysplasia in the upper oesophagus can be treated. At present a major complication of stricture formation is associated with the use of some photosensitisers. The treatment of cancer at the ampulla of Vater and choriocarcinoma is also proving very effective. The treatment can be performed at endoscopy and is well tolerated and safe. [ABSTRACT FROM AUTHOR]

The occurrence of stimulated Raman scattering from within localized density cavities that may be present in many laser-produced plasmas is studied. Then scattering in both the backward and forward directions from a single cavity becomes absolutely unstable, with a common growth rate and zero inhomogeneous plasma thresholds whenever electron plasma waves are totally trapped within the cavity. Both back- and forward scattering mechanisms contribute to this common growth rate. A cavity therefore equalizes the growth of emission in backward and forward directions. Forward scattering in its own right gives rise to absolute growth. The threshold for absolute growth is then set by damping, and by Landau damping of the plasma wave in particular. Only very modest density depressions are needed to trap the long-wavelength weakly damped plasma waves. Absolutely unstable back- and forward scattering from within shallow cavities in the underdense coronal plasmas of laser fusion targets may prove to be commonplace rather than the exception, although growth rates are generally slow and sensitive to the cavity density and scale. [ABSTRACT FROM AUTHOR]

The effect of a plasma filament on the characteristics of stimulated Raman scattering is examined. The model representation of the filament allows an assessment of the way in which Raman growth rates are influenced not only by the density inhomogeneity transverse to the beam direction, but by the nonuniform intensities of the incident laser and scattered light, as well as by Landau damping in the plasma. The model determines global eigenvalues without recourse to local (WKB) approximations, or to phenomenological damping factors. In shallow filaments the concentration of the light gives rise to modest gains in growth, while for deeper filaments the effects of the inhomogeneity and of Landau damping are dominant and suppress the instability. In both cases the strongest growth occurs at the bottom of the filament. Waveguide effects in deep filaments can result in emission being constrained to wavelengths significantly shorter than twice that of the incident laser light. [ABSTRACT FROM AUTHOR]

Presents information on a study which used quantitative urine glucose for the assessment of glucose homeostasis in diabetic children. Methodology; Results; Discussion.

The identification of patients with “bad Barrett's” who are at risk of neoplastic progression is a vital and pressing task. The view that specialized intestinal metaplasia with goblet cells is the predominant preneoplastic phenotype has had wide, but by no means universal, acceptance. An important caveat is presented in the thoughtful paper by Liu et al. in this issue. Of 68 patients with columnar metaplasia, 22 patients had no goblet cells identified and 46 had goblet cells in their biopsies. In both groups there were chromosomal and DNA content abnormalities and genetic instability. However, there were no significant differences between these cellular DNA abnormalities in the two groups. Both were significantly different from gastric controls. Thus, all metaplasia in the columnar-lined esophagus may already be on the path to cancer.Am J Gastroenterol 2009; 104:825–827; doi:10.1038/ajg.2009.90; published online 17 March 2009 [ABSTRACT FROM AUTHOR]

Thresholds and growth rates for stimulated Raman scattering from a plasma density maximum, corresponding to laser–target burnthrough experiments, are obtained by numerical solution of the full-wave Raman scattering equations. This supplements and extends to new regimes the WKB analysis of Rosenbluth [Phys. Rev. Lett. 29, 565 (1972)] and the quasiglobal analysis of Williams and Johnston [Phys. Fluids B 1, 188 (1989)]. The results show unexpected scalings with laser intensity well above threshold, and permit absolutely unstable forward scattering with thresholds comparable to those for backward scattering. [ABSTRACT FROM AUTHOR]

The linear mode conversion of a plasma wave to a light wave in a magnetized plasma has been examined theoretically and by computer simulation. This conversion is the inverse of resonance absorption exhibiting an identical dependence on magnetic field and density scale length with an optimum conversion efficiency of approximately 60%. Radiation from this source may contribute to the harmonic spectra observed from laser-irradiated plasmas. [ABSTRACT FROM AUTHOR]

Three patients with locally recurrent rectal cancer were treated using the Neodymium YAG laser to palliate the symptoms of tenesmus, discharge and bleeding. All were considered unfit for further surgical excision. The local tumour was completely removed following repeated laser therapy over a period of 4, 6 and 11 months, respectively. These patients remain well without evidence of local or systemic disease 26, 33 and 42 months after laser treatment. Laser therapy for palliation of local disease may be rewarded by prolonged local control and possible cure. [ABSTRACT FROM AUTHOR]

Presents an introduction to the papers published in the January 2005 issue of the "Journal of Interprofessional Care."

Proposes that mucosal ablation is the procedure of choice to prevent Barrett's esophagus. Removal of the occult cancer by radical surgical removal; Potential problem in the columnar lined esophagus; Reduction of cancer risk by photodynamic therapy.

Proposes that a patient with a clinical diagnosis of Barrett's oesophagus must have regularly endoscopic surveillance and protocol biopsy. Detectable pre-clinical phase for the disease; Advantages of treating the disease before it becomes symptomatic; Acceptability of surveillance to the patient and the health care provider.

Investigates the use of interstitial laser photocoagulation for the treatment of adenocarcinoma of the stomach. Insertion of sapphire into the center of the tumor; Absence of discomfort among patients during the procedure; Problems on the use of endoscopic laser treatment.

Relates use of endoscopic photodynamic therapy to eradicate high-grade dysplasia. Patients and discussion; Methods used; Findings; Interpretation of the findings.

A correction to the article "Defining a Bad Barrett's Segment: Is It Dependent on Goblet Cells?," that was published in the 2009 issue is presented.

A five-wave Raman scattering process is examined in inhomogeneous plasma in the presence of a finite level of ion acoustic waves. This five-wave interaction is a composite of conventional three-wave stimulated Raman scattering (SRS) followed by the decay of the Raman Langmuir wave into either a second Langmuir wave (LD) or a second scattered light wave (ED) and an ion acoustic wave. The presence of a suprathermal level of ion acoustic waves detunes SRS and inhibits the temporal growth. In inhomogeneous plasma these decays take place locally so that phase matching for both decays is assumed to be coincident. The net Raman convective gain is shown to be sensitive to the source levels of the amplifying waves. For LD the gain may be suppressed or enhanced depending on the relative intensities of the two Langmuir waves. For ED the gain is invariably suppressed. In either case, this occurs for very modest levels of ion acoustic waves. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A unified treatment of electron parametric instabilities driven by ultraintense laser light in plasma is described. The method is valid for laser light of any polarization and intensity, for any plasma density both rarefied and classically overdense, and for any scattering geometry. A fully relativistic self-consistent three-dimensional (3D) analysis, based on the cold electron fluid and Maxwell's equations without further assumption, is carried out in the laser pulse proper frame allowing a concise description in terms of a system of six ordinary differential equations. The approach is applied to linearly polarized laser light in underdense plasma, and overdense plasma accessible by self-induced transparency. Electron charge displacement and relativistic mass fluctuations give rise to hybrids of stimulated Raman scattering, the two plasmon decay, the relativistic modulational and filamentation instabilities, and to stimulated harmonic generation. There is vigorous growth over a wide range of wave numbers and harmonics. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Background The optimal management of patients with Barrett's-associated low-grade dysplasia ( LGD) is unclear. The objective of this study was to identify systematically all reports of endoscopic treatment of LGD, and to assess outcomes in terms of disease progression, eradication of dysplasia and intestinal metaplasia, and complication rates. Methods A systematic review of articles reporting endoscopic treatment of LGD was conducted in accordance with PRISMA guidelines. MEDLINE and Embase databases were searched to identify the relevant literature. Rates of complete eradication of intestinal metaplasia ( CE-IM) and dysplasia ( CE-D) were reported. The pooled incidence of progression to cancer was calculated following endoscopic therapy. Results Thirty-seven studies met the inclusion criteria, reporting outcomes of endoscopic therapy for 521 patients with LGD. The pooled incidence of progression to cancer was 3·90 (95 per cent confidence interval (c.i.) 1·27 to 9·10) per 1000 patient-years. CE-IM and CE-D were achieved in 67·8 (95 per cent c.i. 50·2 to 81·5) and 88·9 (83·9 to 92·5) per cent of patients respectively. The commonest adverse event was stricture formation. Conclusion Reports of endoscopic therapy were heterogeneous and follow-up periods were short. There is a high likelihood of historical overdiagnosis of LGD. Endoscopic therapy, particularly radiofrequency ablation, appears safe and effective at eradicating LGD, but does not eliminate the risk of progression to cancer. [ABSTRACT FROM AUTHOR]

Raman and infrared spectroscopy are optical spectroscopic techniques that use light scattering (Raman) and light absorption (infrared) to probe the vibrational energy levels of molecules in tissue samples. Using these techniques, one can gain an insight into the biochemical composition of cells and tissues by looking at the spectra produced and comparing them with spectra obtained from standards such as proteins, nucleic acids, lipids and carbohydrates. As a result of optical spectroscopy being able to measure these biochemical changes, diagnosis of cancer could take place faster than current diagnostic methods, assisting and offering pathologists and cytologists a novel technology in cancer screening and diagnosis. The purpose of this study is to use both spectroscopic techniques, in combination with multivariate statistical analysis tools, to analyze some of the major biochemical and morphological changes taking place during carcinogenesis and metastasis in lymph nodes and to develop a predictive model to correctly differentiate cancerous from benign lymph nodes taken from oesophageal cancer patients. The results of this study showed that Raman and infrared spectroscopy managed to correctly differentiate between cancerous and benign oesophageal lymph nodes with a training performance greater than 94% using principal component analysis (PCA)-fed linear discriminant analysis (LDA). Cancerous nodes had higher nucleic acid but lower lipid and carbohydrate content compared to benign nodes which is indicative of increased cell proliferation and loss of differentiation. With better understanding of the molecular mechanisms of carcinogenesis and metastasis together with use of multivariate statistical analysis tools, these spectroscopic studies will provide a platform for future development of real-time (in surgery) non-invasive diagnostic tools in medical research. [ABSTRACT FROM AUTHOR]

Barrett's oesophagus (BE) is a premalignant condition that can progress to oesophageal adenocarcinoma. Endoscopic surveillance aims to identify potential progression at an early, treatable stage, but generates large numbers of tissue biopsies. Fourier transform infrared (FTIR) mapping was used to develop an automated histology tool for detection of BE and Barrett's neoplasia in tissue biopsies. 22 oesophageal tissue samples were collected from 19 patients. Contiguous frozen tissue sections were taken for pathology review and FTIR imaging. 45 mid-IR images were measured on an Agilent 620 FTIR microscope with an Agilent 670 spectrometer. Each image covering a 140 μm × 140 μm region was measured in 5 minutes, using a 1.1 μm2 pixel size and 64 scans per pixel. Principal component fed linear discriminant analysis was used to build classification models based on spectral differences, which were then tested using leave-one-sample-out cross validation. Key biochemical differences were identified by their spectral signatures: high glycogen content was seen in normal squamous (NSQ) tissue, high glycoprotein content was observed in glandular BE tissue, and high DNA content in dysplasia/adenocarcinoma samples. Classification of normal squamous samples versus‘abnormal’ samples (any stage of Barrett's) was performed with 100% sensitivity and specificity. Neoplastic Barrett's (dysplasia or adenocarcinoma) was identified with 95.6% sensitivity and 86.4% specificity. Highly accurate pathology classification can be achieved with FTIR measurement of frozen tissue sections in a clinically applicable timeframe. [ABSTRACT FROM AUTHOR]

Background Barrett's oesophagus (BE) is a premalignant condition leading to oesophageal adenocarcinoma (OAC). Treatment of neoplasia at an early stage is desirable. Combined endoscopic mucosal resection (EMR) followed by radiofrequency ablation (RFA) is an alternative to surgery for patients with BErelated neoplasia. Methods We examined prospective data from the UK registry of patients undergoing RFA/EMR for BE-related neoplasia from 2008 to 2013. Before RFA, visible lesions were removed by EMR. Thereafter, patients had RFA 3- monthly until all BE was ablated or cancer developed (endpoints). End of treatment biopsies were recommended at around 12 months from first RFA treatment or when endpoints were reached. Outcomes for clearance of dysplasia (CR-D) and BE (CR-IM) at end of treatment were assessed over two time periods (2008-2010 and 2011-2013). Durability of successful treatment and progression to OAC were also evaluated. Results 508 patients have completed treatment. CR-D and CR-IM improved significantly between the former and later time periods, from 77% and 56% to 92% and 83%, respectively (p<0.0001). EMR for visible lesions prior to RFA increased from 48% to 60% (p=0.013). Rescue EMR after RFA decreased from 13% to 2% (p<0.0001). Progression to OAC at 12 months is not significantly different (3.6% vs 2.1%, p=0.51). Conclusions Clinical outcomes for BE neoplasia have improved significantly over the past 6 years with improved lesion recognition and aggressive resection of visible lesions before RFA. Despite advances in technique, the rate of cancer progression remains 2-4% at 1 year in these high-risk patients. [ABSTRACT FROM AUTHOR]

Objectives Endoscopic ultrasound (EUS) is recommended for staging gastro-oesophageal cancers but has never been rigorously evaluated. This trial assessed whether EUS, when added to usual staging tests: changes treatment; improves survival and quality of life; and uses resources cost-effectively. Methods We conducted a pragmatic randomised trial in eight centres. As 80% of participants came from two centres, we combined the other centres for analysis. Patients diagnosed with gastro-oesophageal cancer received a standard staging protocol, after which the multi-disciplinary team agreed a provisional management plan. In principle the choice lay between endoscopic mucosal resection, immediate surgery, neoadjuvant chemotherapy followed by surgery, or multi-modal treatment (ie chemotherapy and radiotherapy). We then randomised consenting patients without metastases by telephone to receive EUS or not. Thereafter we recorded changes in the management plan, in the use of healthcare resources and in participant-reported outcomes. In particular we focused on three facets of quality of life: generic (measured by the EQ5D), cancer-related (FACT general scale and subscales) and condition-specific (FACT additional concerns scale). We then followed participants at defined intervals till the end of the trial—that is for between one and 3.5 years. Findings We randomised 223 patients, of whom 213 yielded enough data for primary analysis. At the end of the trial 45% of EUS participants and 32% of the non-EUS participants were alive. EUS improved survival adjusted for generic quality of life with an HR of 0.69 (95% CI 0.49 to 0.98); and both its components—survival and EQ5D scores; the benefits of EUS were significantly greater for those with poor initial quality of life, but there was no difference between centres. Similarly, there was a significant interaction between initial quality of life and the effect of EUS on all the FACT scales; again sicker patients benefitted more from EUS. However, there was no significant difference between EUS and non-EUS groups in mean FACT scores adjusted for covariates. Both management plans and final treatment varied between centres. Although EUS changed the management plan for several participants, differences between groups in actual treatment and the proportion of tumours completely resected were not significant. In both groups, two thirds of initial treatment plans were for chemotherapy followed by surgery, but 40% of participants received multi-modal or palliative treatment. Conclusion EUS has a beneficial effect on survival and generic quality of life, especially for participants initially in poorer health. [ABSTRACT FROM PUBLISHER]

Background and review context: Evidence to support the proposition that learning together will help practitioners and agencies work better together remains limited and thinly spread. This review identified, collated, analysed and synthesised the best available contemporary evidence from 21 of the strongest evaluations of IPE to inform the above proposition. In this way we sought to help shape future interprofessional education and maximize the potential for interprofessional learning to contribute to collaborative practice and better care. Objectives of the review: To identify and review the strongest evaluations of IPE. To classify the outcomes of IPE and note the influence of context on particular outcomes. To develop a narrative about the mechanisms that underpin and inform positive and negative outcomes of IPE. Search strategy: Bibliographic database searches as follows: Medline 1966-2003, CINAHL 1982-2001, BEI 1964-2001, ASSIA 1990-2003 which produced 10,495 abstracts. Subsequently, 884 full papers were obtained and scrutinized. In addition, hand searching (2003-5 issues) of 21 journals known to have published two or more higher quality studies from a previous review. Topic definition and inclusion criteria: Peer-reviewed papers and reports included in the review had to be formal educational initiatives attended by at least two of the many professional groups from health and social care, with the objective of improving care; and learning with, from and about each other. Data collection, analysis and synthesis: Standard systematic review procedures were applied for sifting abstracts, scrutinizing full papers and abstracting data. Two members of the team checked each abstract to decide whether the full paper should be read. A third member was consulted over any discrepancies. Similarly, each full paper was read by at least two members of the team and agreement sought before passing it to one member of the team (SR) for data abstraction. Other members of the team checked 10% of the abstraction records. Coding into a Statistical Package for Social Scientists (SPSS) data base led to collection of different outcome measures used in the primary studies via the common metric of an adapted Kirkpatrick's four-level model of educational outcomes. Additionally, a narrative synthesis was built after analysis of primary data with the 3-P model (presage-process-product) of education development and delivery. Headline results: Government calls for enhanced collaboration amongst practitioners frequently leads to IPE that is then developed and delivered by educators, practitioners or service managers. Staff development is a key influence on the effectiveness of IPE for learners who all have unique values about themselves and others. Authenticity and customization of IPE are important mechanisms for positive outcomes of IPE. Interprofessional education is generally well received, enabling knowledge and skills necessary for collaborative working to be learnt; it is less able to positively influence attitudes and perceptions towards others in the service delivery team. In the context of quality improvement initiatives interprofessional education is frequently used as a mechanism to enhance the development of practice and improvement of services. [ABSTRACT FROM AUTHOR]

Several techniques are under development to diagnose oesophageal adenocarcinoma at an earlier stage. We have demonstrated the potential of Raman spectroscopy, an optical diagnostic technique, for the identification and classification of malignant changes. However, there is no clear recognition of the biochemical changes that distinguish between the different stages of disease. Our aim is to understand these changes through Raman mapping studies. Raman spectral mapping was used to analyse 20-microm sections of tissue from 29 snap-frozen oesophageal biopsies. Contiguous haematoxylin and eosin sections were reviewed by a consultant pathologist. Principal component analysis was used to identify the major differences between the spectra across each map. Pseudocolour score maps were generated and the peaks of corresponding loads identified enabling visualisation of the biochemical changes associated with malignancy. Changes were noted in the distribution of DNA, glycogen, lipids and proteins. The mean spectra obtained from selected regions demonstrate increased levels of glycogen in the squamous area compared with increased DNA levels in the abnormal region. Raman spectroscopy is a highly sensitive and specific technique for demonstration of biochemical changes in the carcinogenesis of Barrett's oesophagus. There is potential for in vivo application for real-time endoscopic optical diagnosis. [ABSTRACT FROM AUTHOR]