SERS enhancement of silver nanoparticles prepared by a template-directed triazole ligand strategy.

Two advances in the development of a one-pot method to prepare silver nanoparticles (AgNPs) using the Tollens' reagent are described. First, a template-directed process of AgNP synthesis using resorcinol triazole ligands bearing two pendent galactose sugars is shown. Second, the conversion of these AgNPs into SERS nanotags is demonstrated using malachite green isothiocyanate as the Raman reporter molecule.

Palladium(0) NHC complexes: a new avenue to highly efficient phosphorescence.

We report the first examples of highly luminescent di-coordinated Pd(0) complexes. Five complexes of the form [Pd(L)(L')] were synthesized, where L = IPr, SIPr or IPr* NHC ligands and L' = PCy3, or IPr and SIPr NHC ligands. The photophysical properties of these complexes were determined in degassed toluene solution and in the solid state and contrasted to the poorly luminescent reference complex [Pd(IPr)(PPh3)]. Organic light-emitting diodes were successfully fabricated but attained external quantum efficiencies of between 0.3 and 0.7%.

Mapping glucose-mediated gut-to-brain signalling pathways in humans.

OBJECTIVES: Previous fMRI studies have demonstrated that glucose decreases the hypothalamic BOLD response in humans. However, the mechanisms underlying the CNS response to glucose have not been defined. We recently demonstrated that the slowing of gastric emptying by glucose is dependent on activation of the gut peptide cholecystokinin (CCK1) receptor. Using physiological functional magnetic resonance imaging this study aimed to determine the whole brain response to glucose, and whether CCK plays a central role. EXPERIMENTAL DESIGN: Changes in blood oxygenation level-dependent (BOLD) signal were monitored using fMRI in 12 healthy subjects following intragastric infusion (250ml) of: 1M glucose+predosing with dexloxiglumide (CCK1 receptor antagonist), 1M glucose+placebo, or 0.9% saline (control)+placebo, in a single-blind, randomised fashion. Gallbladder volume, blood glucose, insulin, and GLP-1 and CCK concentrations were determined. Hunger, fullness and nausea scores were also recorded. PRINCIPAL OBSERVATIONS: Intragastric glucose elevated plasma glucose, insulin, and GLP-1, and reduced gall bladder volume (an in vivo assay for CCK secretion). Glucose decreased BOLD signal, relative to saline, in the brainstem and hypothalamus as well as the cerebellum, right occipital cortex, putamen and thalamus. The timing of the BOLD signal decrease was negatively correlated with the rise in blood glucose and insulin levels. The glucose+dex arm highlighted a CCK1-receptor dependent increase in BOLD signal only in the motor cortex. CONCLUSIONS: Glucose induces site-specific differences in BOLD response in the human brain; the brainstem and hypothalamus show a CCK1 receptor-independent reduction which is likely to be mediated by a circulatory effect of glucose and insulin, whereas the motor cortex shows an early dexloxiglumide-reversible increase in signal, suggesting a CCK1 receptor-dependent neural pathway.

Using read codes to identify patients with irritable bowel syndrome in general practice: a database study.

BACKGROUND: Estimates of the prevalence of irritable bowel syndrome (IBS) vary widely, and a large proportion of patients report having consulted their general practitioner (GP). In patients with new onset gastrointestinal symptoms in primary care it might be possible to predict those at risk of persistent symptoms. However, one of the difficulties is identifying patients within primary care. GPs use a variety of Read Codes to describe patients presenting with IBS. Furthermore, in a qualitative study, exploring GPs' attitudes and approaches to defining patients with IBS, GPs appeared reluctant to add the IBS Read Code to the patient record until more serious conditions were ruled out. Consequently, symptom codes such as 'abdominal pain', 'diarrhoea' or 'constipation' are used. The aim of the current study was to investigate the prevalence of recorded consultations for IBS and to explore the symptom profile of patients with IBS using data from the Salford Integrated Record (SIR). METHODS: This was a database study using the SIR, a local patient sharing record system integrating primary, community and secondary care information. Records were obtained for a cohort of patients with gastrointestinal disorders from January 2002 to December 2011. Prevalence rates, symptom recording, medication prescribing and referral patterns were compared for three patient groups (IBS, abdominal pain (AP) and Inflammatory Bowel Disease (IBD)). RESULTS: The prevalence of IBS (age standardised rate: 616 per year per 100,000 population) was much lower than expected compared with that reported in the literature. The majority of patients (69%) had no gastrointestinal symptoms recorded in the year prior to their IBS. However a proportion of these (22%) were likely to have been prescribed NICE guideline recommended medications for IBS in that year. The findings for AP and IBD were similar. CONCLUSIONS: Using Read Codes to identify patients with IBS may lead to a large underestimate of the community prevalence. The IBS diagnostic Read Code was rarely applied in practice. There are similarities with many other medically unexplained symptoms which are typically difficult to diagnose in clinical practice.

Synthesis, characterization and luminescence studies of gold(I)-NHC amide complexes.

A flexible, efficient and straightforward methodology for the synthesis of N-heterocyclic carbene gold(I)-amide complexes is reported. Reaction of the versatile building block [Au(OH)(IPr)] (1) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) with a series of commercially available (hetero)aromatic amines leads to the synthesis of several [Au(NRR')(IPr)] complexes in good yields and with water as the sole byproduct. Interestingly, these complexes present luminescence properties. UV-vis and fluorescence measurements have allowed the identification of their excitation and emission wavelengths (λmax). These studies revealed that by selecting the appropriate amine ligand the emission can be easily tuned to achieve a variety of colors, from violet to green.

GP perspectives of irritable bowel syndrome--an accepted illness, but management deviates from guidelines: a qualitative study.

BACKGROUND: The estimated prevalence of irritable bowel syndrome (IBS) is 10%. Up to one third of patients develop chronic symptoms, which impact on everyday functioning and psychological wellbeing. Guidelines suggest an increased role for primary care in the management of patients with IBS, and referral for psychological interventions. Literature reports dissatisfaction and frustration experienced by both patients with IBS and healthcare professionals. The aim of this study was to explore the perspectives of general practitioners (GPs) in relation to the diagnosis and management of IBS and their views on the potential use of a risk assessment tool to aid management decisions for patients with IBS in primary care. METHODS: This was a qualitative study using face-to-face semi-structured interviews with GPs in North West England. Interviews were fully transcribed and data analyzed using constant comparison across interviews. Tensions between GP accounts and the NICE guideline for the management of IBS were highlighted. RESULTS: GPs described IBS as a diagnosis of exclusion and the process as tentative and iterative, with delay in adding a Read code to the patient record until they were confident of the diagnosis. Whilst GPs accepted there was a link between IBS and psychological symptoms they suggested that the majority of patients could be managed within primary care without referral for psychological interventions, in conflict with the NICE guideline. They did not feel that a risk assessment tool for patients with IBS would be helpful. CONCLUSIONS: This study highlights the tensions between evidence recognizing the need to identify patients whose symptoms may become chronic and offer pro-active care, including referral for psychological therapies, and the perspectives of GPs managing patients in every-day clinical practice. The reluctance of GPs to refer patients for evidence-based psychological treatments may have implications for commissioning services and patient care.

Functional neuroimaging demonstrates that ghrelin inhibits the central nervous system response to ingested lipid.

OBJECTIVE: Gut-derived humoural factors activate central nervous system (CNS) mechanisms controlling energy intake and expenditure, and autonomic outflow. Ghrelin is secreted from the stomach and stimulates food intake and gastric emptying, but the relevant mechanisms are poorly understood. Nutrient-activated CNS systems can be studied in humans by physiological/pharmacological MRI (phMRI). This method has been used to examine the CNS responses to exogenous ghrelin. DESIGN: phMRI was used to study the CNS responses in healthy people to a ghrelin bolus (0.3 nmol/kg, intravenous) in the post-prandial state, and an intravenous infusion of ghrelin (1.25 pmol/kg/min) alone and after intragastric lipid (dodecanoate, C12) in people who have fasted. RESULTS: A ghrelin bolus decreased the blood oxygenation level dependent (BOLD) signal detected by phMRI in feeding-activated areas of the CNS in the post-prandial state. Infusion of ghrelin reversed the effect of C12 in delaying gastric emptying but had no effect on hunger. Intragastric C12 caused strong bilateral activation of a matrix of CNS areas, including the brain stem, hypothalamus and limbic areas which was attenuated by exogenous ghrelin. Ghrelin infusion alone had a small but significant stimulatory effect on CNS BOLD signals. CONCLUSION: Ghrelin inhibits activation of the hypothalamus and brain stem induced by ingested nutrients, suggesting a role in suppression of gut-derived satiety signals in humans.

Microscale mesoarrays created by dip-pen nanolithography for screening of protein-protein interactions.

Using microarrays to probe protein-protein interactions is becoming increasingly attractive due to their compatibility with highly sensitive detection techniques, selectivity of interaction, robustness and capacity for examining multiple proteins simultaneously. The major drawback to using this approach is the relatively large volumes and high concentrations necessary. Reducing the protein array spot size should allow for smaller volumes and lower concentrations to be used as well as opening the way for combination with more sensitive detection technologies. Dip-Pen Nanolithography (DPN) is a recently developed technique for structure creation on the nano to microscale with the capacity to create biological architectures. Here we describe the creation of miniaturised microarrays, 'mesoarrays', using DPN with protein spots 400× smaller by area compared to conventional microarrays. The mesoarrays were then used to probe the ERK2-KSR binding event of the Ras/Raf/MEK/ERK signalling pathway at a physical scale below that previously reported. Whilst the overall assay efficiency was determined to be low, the mesoarrays could detect KSR binding to ERK2 repeatedly and with low non-specific binding. This study serves as a first step towards an approach that can be used for analysis of proteins at a concentration level comparable to that found in the cellular environment.

Combining functionalised nanoparticles and SERS for the detection of DNA relating to disease.

DNA functionalised nanoparticle probes offer new opportunities in analyte detection. Ultrasensitive, molecularly specific targeting of analytes is possible through the use of metallic nanoparticles and their ability to generate a surface enhanced Raman scattering (SERS) response. This is leading to a new range of diagnostic clinical probes based on SERS detection. Our approaches have shown how such probes can detect specific DNA sequences by using a biomolecular recognition event to 'turn on' a SERS response through a controlled assembly process of the DNA functionalised nanoparticles. Further, we have prepared DNA aptamer functionalised SERS probes and demonstrated how introduction of a protein target can change the aggregation state of the nanoparticles in a dose-dependant manner. These approaches are being used as methods to detect biomolecules that indicate a specific disease being present with a view to improving disease management.

Expression of cannabinoid CB1 receptors by vagal afferent neurons: kinetics and role in influencing neurochemical phenotype.

The intestinal hormone cholecystokinin (CCK) inhibits food intake via stimulation of vagal afferent neurons (VAN). Recent studies suggest that CCK also regulates the expression of some G protein-coupled receptors and neuropeptide transmitters in these neurons. The aim of the present study was to characterize the expression of cannabinoid (CB)1 receptors in VAN and to determine whether stimulation of these receptors plays a role in regulating neurochemical phenotype. Expression of CB1 in rat VAN was detectable by in situ hybridization or immunohistochemistry after 6 h of fasting and increased to a maximum after 24 h when approximately 50% of neurons in the mid and caudal regions expressed the receptor. Melanin-concentrating hormone (MCH)1 receptors also increased with fasting, but the changes were delayed compared with CB1; in contrast Y2 receptors (Y2R) exhibited reciprocal changes in expression to CB1. Administration of CCK8s (10 nmol ip) to fasted rats decreased expression of CB1 with a t(1/2) of approximately 1 h compared with 3 h for MCH1. The action of CCK8s was inhibited by ghrelin and orexin-A. The CB1 agonist anandamide (intraperitoneally) reversed the effect of CCK8s on CB1, MCH1, and Y2 receptor expression. In contrast, in rats fasted for 18 h, administration of a CB1 antagonist/inverse agonist (AM281 ip) downregulated CB1 expression and increased Y2 receptor expression. Activation of vagal CB1 receptors therefore influences the neurochemical phenotype of these neurons, indicating a new and hitherto unrecognized role for endocannabinoids in gut-brain signaling.

Sweetness and bitterness taste of meals per se does not mediate gastric emptying in humans.

In cell line and animal models, sweet and bitter tastants induce secretion of signaling peptides (e.g., glucagon-like peptide-1 and cholecystokinin) and slow gastric emptying (GE). Whether human GE and appetite responses are regulated by the sweetness or bitterness per se of ingested food is, however, unknown. We aimed to determine whether intragastric infusion of "equisweet" (Study A) or "equibitter" (Study B) solutions slow GE to the same extent, and whether a glucose solution made sweeter by the addition of saccharin will slow GE more potently than glucose alone. Healthy nonobese subjects were studied in a single-blind, randomized fashion. Subjects received 500-ml intragastric infusions of predetermined equisweet solutions of glucose (560 mosmol/kgH(2)O), fructose (290 mosmol/kgH(2)O), aspartame (200 mg), and saccharin (50 mg); twice as sweet glucose + saccharin, water (volumetric control) (Study A); or equibitter solutions of quinine (0.198 mM), naringin (1 mM), or water (Study B). GE was evaluated using a [(13)C]acetate breath test, and hunger and fullness were scored using visual analog scales. In Study A, equisweet solutions did not empty similarly. Fructose, aspartame, and saccharin did not slow GE compared with water, but glucose did (P < 0.05). There was no additional effect of the sweeter glucose + saccharin solution (P > 0.05, compared with glucose alone). In Study B, neither bitter tastant slowed GE compared with water. None of the solutions modulated perceptions of hunger or fullness. We conclude that, in humans, the presence of sweetness and bitterness taste per se in ingested solutions does not appear to signal to influence GE or appetite perceptions.

Predicting aspiration after hemispheric stroke from timing measures of oropharyngeal bolus flow and laryngeal closure.

Deglutitive aspiration is common after stroke, affecting up to 50% of patients and predisposing them to pneumonia, yet it is virtually impossible to predict those patients at greatest risk. The aim of this study was to develop a robust predictive model for aspiration after stroke. Swallowing was assessed by digital videofluoroscopy (VF) in 90 patients following hemispheric stroke. Lesion characteristics were determined by computerized tomography (CT) brain scan using the Alberta Stroke Programme Early CT Score (ASPECTS). Aspiration severity was measured using a validated penetration-aspiration scale. The probability of aspiration was then determined from measures of swallowing pathophysiology and lesion location by discriminant analysis. Aspiration was observed in 47 (52%) patients, yet despite disrupted swallowing physiology, intrasubject aspiration scores were variable. The best discriminant model combined pharyngeal transit time, swallow response time, and laryngeal closure duration to predict 73.11% of those aspirating (sensitivity = 66.54, specificity = 80.22, p > 0.001). The addition of lesion location did not add anything further to the predictive model. We conclude that the pathophysiology of poststroke aspiration is multifactorial but in most cases can be predicted by three key swallowing measurements. These measurements, if translatable into clinical bedside evaluation, may assist with the development of novel measurement and intervention techniques to detect and treat poststroke aspiration.

Cholecystokinin regulates expression of Y2 receptors in vagal afferent neurons serving the stomach.

The intestinal hormones CCK and PYY3-36 inhibit gastric emptying and food intake via vagal afferent neurons. Here we report that CCK regulates the expression of Y2R, at which PYY3-36 acts. In nodose ganglia from rats fasted up to 48 h, there was a fivefold decrease of Y2R mRNA compared with rats fed ad libitum; Y2R mRNA in fasted rats was increased by administration of CCK, and by refeeding through a mechanism sensitive to the CCK1R antagonist lorglumide. Antibodies to Y2R revealed expression in both neurons and satellite cells; most of the former (89 +/- 4%) also expressed CCK1R. With fasting there was loss of Y2R immunoreactivity in CCK1R-expressing neurons many of which projected to the stomach, but not in satellite cells or neurons projecting to the ileum or proximal colon. Expression of a Y2R promoter-luciferase reporter (Y2R-luc) in cultured vagal afferent neurons was increased in response to CCK by 12.3 +/- 0.1-fold and by phorbol ester (16.2 +/- 0.4-fold); the response to both was abolished by the protein kinase C inhibitor Ro-32,0432. PYY3-36 stimulated CREB phosphorylation in rat nodose neurons after priming with CCK; in wild-type mice PYY3-36 increased Fos labeling in brainstem neurons but in mice null for CCK1R this response was abolished. Thus Y2R is expressed by functionally distinct subsets of nodose ganglion neurons projecting to the stomach and ileum/colon; in the former expression is dependent on stimulation by CCK, and there is evidence that PYY3-36 effects on vagal afferent neurons are CCK dependent.

Control of enhanced Raman scattering using a DNA-based assembly process of dye-coded nanoparticles.

Enhanced Raman scattering from metal surfaces has been investigated for over 30 years. Silver surfaces are known to produce a large effect, and this can be maximized by producing a roughened surface, which can be achieved by the aggregation of silver nanoparticles. However, an approach to control this aggregation, in particular through the interaction of biological molecules such as DNA, has not been reported. Here we show the selective turning on of the surface enhanced resonance Raman scattering effect on dye-coded, DNA-functionalized, silver nanoparticles through a target-dependent, sequence-specific DNA hybridization assembly that exploits the electromagnetic enhancement mechanism for the scattering. Dye-coded nanoparticles that do not undergo hybridization experience no enhancement and hence do not give surface enhanced resonance Raman scattering. This is due to the massive difference in enhancement from nanoparticle assemblies compared with individual nanoparticles. The electromagnetic enhancement is the dominant effect and, coupled with an understanding of the surface chemistry, allows surface enhanced resonance Raman scattering nanosensors to be designed based on a natural biological recognition process.

The relationship between somatisation and outcome in patients with severe irritable bowel syndrome.

OBJECTIVE: This study aimed to assess the relationship between somatisation and outcome in patients with severe irritable bowel syndrome (IBS). METHOD: Two hundred fifty-seven patients with severe IBS included in a randomised controlled trial were assessed at baseline and divided into four quartiles on the basis of their somatisation score. The patients were randomised to receive the following over 3 months: brief interpersonal psychotherapy, 20 mg daily of the SSRI antidepressant paroxetine, or treatment as usual. Outcome 1 year after treatment was assessed using the Short Form-36 physical component summary (PCS) score and total costs for posttreatment year. RESULTS: The patients in the quartile with the highest baseline somatisation score had the most severe IBS, the most concurrent psychiatric disorders, and the highest total costs for the year prior to baseline. At 1 year after the end of treatment, however, the patients with marked somatisation, who received psychotherapy or antidepressant, had improved health status compared to those who received usual care: mean (S.E.) PCS scores at 15 months were 36.6 (2.2), 35.5 (1.9), and 26.4 (2.7) for psychotherapy, antidepressant, and treatment-as-usual groups, respectively (adjusted P=.014). Corresponding data for total costs over the year following the trial, adjusted for baseline costs, were pound 1092 (487), pound 1394 (443), and pound 2949 (593) (adjusted P=.050). CONCLUSIONS: Patients with severe IBS who have marked somatisation improve with treatment like other IBS patients and show a greater reduction of costs. Antidepressants and psychotherapy are cost-effective treatments in severe IBS accompanied by marked somatisation.

Ultrasensitive DNA detection using oligonucleotide-silver nanoparticle conjugates.

Oligonucleotide-gold nanoparticle (OGN) conjugates are powerful tools for the detection of target DNA sequences due to the unique properties conferred upon the oligonucleotide by the nanoparticle. Practically all the research and applications of these conjugates have used gold nanoparticles to the exclusion of other noble metal nanoparticles. Here we report the synthesis of oligonucleotide-silver nanoparticle (OSN) conjugates and demonstrate their use in a sandwich assay format. The OSN conjugates have practically identical properties to their gold analogues and due to their vastly greater extinction coefficient both visual and absorption analyses can occur at much lower concentrations. This is the first report of OSN conjugates being successfully used for target DNA detection and offers improved sensitivity which is of interest to a range of scientists.

Unilateral suppression of pharyngeal motor cortex to repetitive transcranial magnetic stimulation reveals functional asymmetry in the hemispheric projections to human swallowing.

Inhibitory patterns of repetitive transcranial magnetic stimulation (rTMS) were applied to pharyngeal motor cortex in order to establish its role in modulating swallowing activity and provide evidence for functionally relevant hemispheric asymmetry. Healthy volunteers underwent single pulse TMS before and for 60 min after differing intensities of 1 Hz rTMS (n = 9, 6 male, 3 female, mean age 34 +/- 3 years) or theta burst stimulation (TBS) (n = 9, 6 male, 3 female, mean age 37 +/- 4 years). Electromyographic responses recorded from pharynx and hand were used as a measure of cortico-motor pathway excitability. Swallowing behaviour was then examined with a reaction time protocol, before and for up to 60 min after the most effective inhibitory protocol (1 Hz) applied to each hemisphere. Interventions were conducted on separate days and compared to sham using ANOVA. Only high intensity 1 Hz rTMS consistently suppressed pharyngeal motor cortex immediately and for up to 45 min (-34 +/- 7%, P < or = 0.001). Adjacent hand and contralateral pharyngeal motor cortex showed no change in response (-15 +/- 12%, P = 0.14 and 15 +/- 12%, P = 0.45, respectively). When used to unilaterally disrupt each hemisphere, rTMS to pharyngeal motor cortex with the stronger responses altered normal (-12 +/- 3%, P < or = 0.001) and fast (-9 +/- 4%, P < or = 0.009) swallow times, not seen following rTMS to the contralateral cortex or after sham. Thus, suppression of pharyngeal motor cortex to rTMS is intensity and frequency dependent, which when applied to each hemisphere reveals functionally relevant asymmetry in the motor control of human swallowing.