Near-field enhanced ultraviolet resonance Raman spectroscopy using aluminum bow-tie nano-antenna.

An aluminum bow-tie nano-antenna is combined with the resonance Raman effect in the deep ultraviolet to dramatically increase the sensitivity of Raman spectra to a small volume of material, such as benzene used here. We further demonstrate gradient-field Raman peaks for several strong infrared modes. We achieve a gain of [Formula: see text] in signal intensity from the near field enhancement due to the surface plasmon resonance in the aluminum nanostructure. The on-line resonance enhancement contributes another factor of several thousands, limited by the laser line width. Thus, an overall gain of hundreds of million is achieved.

Comparison of diffraction-enhanced computed tomography and monochromatic synchrotron radiation computed tomography of human trabecular bone.

Diffraction-enhanced imaging (DEI) is an x-ray-based medical imaging modality that, when used in tomography mode (DECT), can generate a three-dimensional map of both the apparent absorption coefficient and the out-of-plane gradient of the index of refraction of the sample. DECT is known to have contrast gains over monochromatic synchrotron radiation CT (SRCT) for soft tissue structures. The goal of this experiment was to compare contrast-to-noise ratio (CNR) and resolution in images of human trabecular bone acquired using SRCT with images acquired using DECT. All images were acquired at the National Synchrotron Light Source (Upton, NY, USA) at beamline X15 A at an x-ray energy of 40 keV and the silicon [3 3 3] reflection. SRCT, apparent absorption DECT and refraction DECT slice images of the trabecular bone were created. The apparent absorption DECT images have significantly higher spatial resolution and CNR than the corresponding SRCT images. Thus, DECT will prove to be a useful tool for imaging applications in which high contrast and high spatial resolution are required for both soft tissue features and bone.

The effects of probe boundary conditions and propagation on nano-Raman spectroscopy.

Raman spectra obtained in the near-field, with collection of the Raman-shifted light in reflection, show selective enhancement of vibrational modes. We show that the boundary conditions for an electric field near a metal surface affect propagation of the reflected signal and lead to this selection. The enhancement of certain Raman forbidden vibrations is explained by the presence of an electric field gradient near the metal-apertured fibre probe.

Fundamental differences between micro- and nano-Raman spectroscopy.

Electric field polarization orientations and gradients close to near-field scanning optical microscope (NSOM) probes render nano-Raman fundamentally different from micro-Raman spectroscopy. With x-polarized light incident through an NSOM aperture, transmitted light has x, y and z components allowing nano-Raman investigators to probe a variety of polarization configurations. In addition, the strong field gradients in the near-field of a NSOM probe lead to a breakdown of the assumption of micro-Raman spectroscopy that the field is constant over molecular dimensions. Thus, for nano-Raman spectroscopy with an NSOM, selection rules allow for the detection of active modes with intensity dependent on the field gradient. These modes can have similar activity as infra-red absorption modes. The mechanism can also explain the origin and intensity of some Raman modes observed in surface enhanced Raman spectroscopy.

Evaluation of a new method for assessing symptoms.

BACKGROUND: Many studies in rhinology are based on results from symptom scoring. Numerous methods are used to estimate symptoms. With some of them the patients choose between various alternatives for estimating the severity of their symptoms, but the commonest method is the visual analogue scale (VAS), which is regarded as reliable. METHODS: In this study, we evaluate a new method for assessing symptoms, with which the patient uses the telephone to call a computer. We compare the results using the new method with those using symptoms estimation with VAS. RESULTS: The results are based on 487 observations in patients with birch pollen allergic rhinitis in the pollen season. A high correlation was found between the results using the new method and those using the VAS. In a questionnaire, the patients answered questions concerning the two methods. Most patients preferred the new telephone method. They found it easier to estimate their symptoms properly and easier to perform. CONCLUSION: We conclude that telephone scoring of symptoms is a reliable and adequate method when symptom scoring is used as hard data in a study.

Electric field gradient effects in raman spectroscopy.

Raman spectra of materials subject to strong electric field gradients, such as those present near a metal surface, can show significantly altered selection rules. We describe a new mechanism by which the field gradients can produce Raman-like lines. We develop a theoretical model for this "gradient-field Raman" effect, discuss selection rules, and compare to other mechanisms that produce Raman-like lines in the presence of strong field gradients. The mechanism can explain the origin and intensity of some Raman modes observed in SERS and through a near-field optical microscope (NSOM-Raman).

Nasal mucosal swelling and reactivity during a menstrual cycle.

INTRODUCTION: Nasal stuffiness is a great problem for many women in the later part of pregnancy. OBJECTIVE: This study was performed to evaluate whether oestrogen causes nasal congestion and/or a hyperreactive reaction of the nasal mucosa. MATERIAL AND METHODS: Ten healthy fertile women were examined during menstruation. Nasal mucosal congestion was studied with rhinostereometry and acoustic rhinometry. The nasal mucosa was challenged with 3 doses of histamine solution to study nasal reactivity. Measurements were made 3 times during menstruation. To find the exact time of ovulation, when oestrogen reaches its peak value, intravaginal ultrasound tests were done and blood samples taken, to determine the oestrogen and progesterone levels. RESULTS: The nasal mucosa became hyperreactive to histamine in connection with ovulation, when the blood level of oestrogen reached its peak. This does not occur during the menstrual or the luteal phase. No significant alteration was found in the baseline position during the menstruation. CONCLUSION: There is a connection between high oestrogen level and nasal mucosal reactivity.

Ten days' use of oxymetazoline nasal spray with or without benzalkonium chloride in patients with vasomotor rhinitis.

CONTEXT: In most countries, the use of topical nasal decongestants is limited to a maximum of 10 days because of the risk of developing rebound mucosal swelling and rhinitis medicamentosa. OBJECTIVE: To determine whether topical nasal decongestants can be safely used for 10 days in patients with chronic inflammation of the nasal mucosa. DESIGN: Double-blind, randomized, controlled, parallel study. PATIENTS: Thirty-five patients with vasomotor rhinitis selected from our outpatient department. INTERVENTION: Eighteen patients received oxymetazoline hydrochloride (0.5 mg/mL) nasal spray containing the preservative benzalkonium chloride (0.1 mg/mL), and the other 17 were treated with oxymetazoline nasal spray without benzalkonium chloride. Before and after the treatment, recordings of the nasal mucosa and minimal cross-sectional area were made with rhinostereometry and acoustic rhinometry, followed by histamine hydrochloride challenge tests. Symptoms of nasal stuffiness were estimated on visual analog scales (0-100) in the morning and the evening, just before the nasal spray was used. RESULTS: No rebound swelling was found after the 10-day treatment in the 2 groups with either of the methods or as estimated by symptom scores. In the group receiving oxymetazoline containing benzalkonium chloride, but not in the other group, the histamine sensitivity was significantly reduced after treatment (P<.001). CONCLUSIONS: It is safe to use topical nasal oxymetazoline with or without benzalkonium chloride for 10 days in patients with vasomotor rhinitis. However, this study indicates that benzalkonium chloride in nasal decongestant sprays affects the nasal mucosa also after short-term use.

Effects of sustained-release oral phenylpropanolamine on the nasal mucosa of healthy subjects.

Phenylpropanolamine (PPA) is widely used as a nasal decongestant administered orally in sustained release preparations and, in Sweden, the recommended dose nowadays is 50 mg twice daily for adults. The aim of this placebo-controlled, cross-over study was to determine the onset and duration of the decongestive effect of 50 and 100 mg PPA in 15 healthy subjects. All subjects arrived at the laboratory at 07.30 h. After an acclimatisation, the nasal mucosal baseline was established with rhinostereometry and the minimal cross-sectional area was measured using acoustic rhinometry. The systolic and diastolic blood pressures were also determined. Then all subjects were given their study drugs for the day and the measurements were repeated every hour for 8 h. This procedure was repeated for 3 days at 48 h intervals between the days. For purposes of comparison, the decongestive effect of oxymetazoline nasal spray was studied on a separate day. The decongestive effect of 100 mg PPA was similar to that of topical oxymetazoline. It develops after 1 h and lasts for approximately 6 h. The decongestive effect of oxymetazoline was significantly greater than that of 50 mg PPA and that of 100 mg PPA was significantly greater than that of 50 mg PPA using rhinostereometry, but not when using acoustic rhinometry. However, 50 mg PPA had no significant decongestive effect, compared with placebo, with rhinostereometry or acoustic rhinometry. In the first 3 h after administration of PPA, there was a dose-response increase in the systolic and diastolic blood pressures, which then returned to baseline. In conclusion, this study shows that PPA in double the recommended dose, i.e. 100 mg, has a significant decongestive effect on the nasal mucosa in healthy subjects. However, when the dose of PPA is increased the systolic and diastolic blood pressures also increase.

Evaluation of rhinostereometry compared with acoustic rhinometry.

Measurement of the nasal mucosa is a challenging task. There are many different methods; each with advantages and disadvantages. In the last decade two new methods have been used extensively: acoustic rhinometry and rhinostereometry. Many studies with rhinostereometry have shown interesting results. However, there have been doubts about this method, since only a few investigators have used it, and it has never been compared with other methods. On the other hand, the acoustic rhinometer has been compared with many other methods. In this study, we compare the results of measurements with acoustic rhinometry and rhinostereometry. Thirty patients with vasomotor rhinitis participated in the study. They were challenged with three histamine concentrations on two occasions. resulting in 180 observations with each method. The results were compared with each other using the linear correlation test, and showed a poor but significant correlation (p < 0.01. r = 0.25). We conclude that acoustic rhinometry and rhinostereometry are sensitive methods for studying nasal mucosal swelling, but that there is poor correlation between the two methods.

Changes in nasal reactivity in patients with rhinitis medicamentosa after treatment with fluticasone propionate and placebo nasal spray.

AIM OF THE STUDY: To study the changes in nasal reactivity in patients with rhinitis medicamentosa during treatment with placebo or fluticasone propionate, in order to better understand the mechanisms of nasal congestion in such patients. STUDY DESIGN: A parallel, double-blind study. Twenty patients with rhinitis medicamentosa were randomized to either placebo or fluticasone treatment during 14 days. MATERIAL AND METHODS: Nasal mucosa reactivity was studied with a histamine challenge model using three concentrations of histamine to challenge the nasal mucosa (1, 2 and 4 mg histamine/ml). Recordings of the nasal mucosa response were made 5 min after each challenge, using rhinostereometry and acoustic rhinometry, before and after the period of treatment. RESULTS: The fluticasone group had a significantly increased histamine sensitivity after treatment, unlike the placebo group who had an unchanged or slightly decreased histamine sensitivity after treatment. CONCLUSIONS: The results of this study support the theory that the nasal obstruction in rhinitis medicamentosa is due to interstitial oedema rather than to vasodilatation. On the first day of vasoconstrictor withdrawal, the inferior concha was congested and oedematous with a limited capacity to respond to histamine challenge. However, after 14 days of treatment with a corticosteroid nasal spray, the oedema was reduced and the increase in histamine sensitivity reflected the persistence of nasal hyperrreactivity. In the placebo group, histamine sensitivity remains unchanged with the measuring technique we used. This probably indicates that oedema was still present after treatment.

Fluticasone propionate nasal spray is more effective and has a faster onset of action than placebo in treatment of rhinitis medicamentosa.

BACKGROUND: Controversy still exists about the treatment of rhinitis medicamentosa and treatment has never been objectively evaluated. OBJECTIVE: To study the effect of fluticasone propionate aqueous nasal spray compared to placebo nasal spray in the treatment of rhinitis medicamentosa. METHODS: A parallel randomized, double-blind study was conducted to evaluate the treatment of rhinitis medicamentosa. Two groups containing 10 patients with rhinitis medicamentosa in each group stopped their overuse of nasal vasoconstrictor spray immediately and were treated with either fluticasone propionate nasal spray once daily 200 micrograms, or placebo nasal spray for 14 days. The nasal mucosal swelling was recorded with rhinostereometry, acoustic rhinometry and a peak inspiratory flow meter. Nasal stuffiness was estimated on a visual analogue scale in the morning and in the evening of each day. RESULTS: The mucosal swelling decreased after 7 and 14 days of treatment with fluticasone propionate as well as placebo, but the reduction was significantly greater after treatment with fluticasone propionate. The symptom scores for nasal stuffiness showed a marked reduction during the treatment period in both groups, but there was a faster onset of symptom reduction after treatment with fluticasone propionate. CONCLUSION: Fluticasone propionate is more effective and has a faster onset of action than placebo in the treatment of rhinitis medicamentosa. An adequate treatment of these patients consists of a combination of vasoconstrictor withdrawal and a topical corticosteroid to alleviate the withdrawal process.

One year follow-up of patients with rhinitis medicamentosa after vasoconstrictor withdrawal.

The aim of the study was to systematically follow-up 10 patients with rhinitis medicamentosa for at least 1 year after vasoconstrictor withdrawal. During withdrawal of the decongestants the patients used budesonide nasal spray, 400 micrograms/day, for 6 weeks. The thickness of the nasal mucosa, the decongestive effect of oxymetazoline, and the histamine sensitivity were measured with rhinostereometry during the period. The thickness of the nasal mucosa and the symptom scores of nasal stuffiness were reduced considerably 6 and 12 months after vasoconstrictor withdrawal. The histamine sensitivity reflecting nasal hyperreactivity was still increased after 6 months, but not after 1 year. The decongestive effect of oxymetazoline increased after 6 months, indicating reversible tolerance. We conclude that when given adequate treatment and information about nose-drop overuse, all patients were able to stop using the vasoconstrictors and no one relapsed into a daily long-term overuse of vasoconstrictors during the 1-year follow-up period.

One-week use of oxymetazoline nasal spray in patients with rhinitis medicamentosa 1 year after treatment.

The aim of the present study was to investigate whether patients with rhinitis medicamentosa who stopped using the topical vasoconstrictors may use these drugs again more than 1 year later. Eight patients received oxymetazoline nasal spray containing benzalkonium chloride 3 times daily for 7 days, 13-19 months after they had stopped using nasal decongestant sprays containing benzalkonium chloride. Before starting the course of treatment and after its conclusion, recordings of the mucosal surface positions were made with rhinostereometry, followed by histamine challenge tests. Symptoms of nasal stuffiness were estimated on visual analogue scales (0-100). After 7 days, nasal stuffiness, estimated by symptom scores and measurements of nasal mucosa swelling, was found, as well as an increased histamine sensitivity, which was interpreted as a sign of nasal hyperreactivity. In conclusion, patients with rhinitis medicamentosa who overuse topical decongestants and are able to stop using such drugs should be careful about taking these drugs again, even for a few days. They must be informed about the fast onset of rebound congestion upon repeated use in order to avoid the return of the vicious circle of nose drop abuse.

Variations in congestion of the nasal mucosa in man.

Congestion of one side of the nose is accompanied by decongestion of the other side. This is called the nasal cycle. The nasal cycle does not seem to be present in all subjects and it has not been shown with rhinostereometry. There are very few studies showing whether there are spontaneous day-to-day variations in nasal mucosal congestion and no studies showing differences in nasal mucosal congestion between morning and afternoon. This, however, may be very important in studies covering a longer period. In the present study, data from four healthy volunteers were recorded 18 or 19 times in the mornings and afternoons on different days. Measurements were made with rhinostereometry, a peak flow meter (PNIF) and by symptom scores. A nasal cycle was found in some subjects. There was no difference in total nasal mucosal swelling in the mornings and in the afternoons and no day-to-day variation in the total nasal mucosal swelling.

Effect on the nasal mucosa of long-term treatment with oxymetazoline, benzalkonium chloride, and placebo nasal sprays.

A parallel, randomized, double-blind study was performed in 30 healthy subjects to investigate the effects on the nasal mucosa of a 1-month treatment with nasal sprays. Ten subjects received oxymetazoline nasal spray; 10 subjects used a nasal spray containing the preservative benzalkonium chloride, and the others were treated with a placebo nasal spray. The three variables that were studied --nasal mucosal swelling, symptom scores, and nasal reactivity-- were estimated by histamine challenge before and after 28 days of treatment. Rhinostereometry was used to measure nasal mucosal swelling and nasal reactivity. After 28 days of use, benzalkonium chloride spray alone induced an increase in nasal mucosal swelling. At the end of the month, the score for nasal stuffiness was significantly higher for the group treated with oxymetazoline than for those treated with benzalkonium chloride. Oxymetazoline nasal spray induced a pronounced increase in nasal reactivity, which was significantly greater than that induced in the placebo group. Long-term use of placebo and benzalkonium chloride nasal sprays also caused an increase in nasal reactivity, but not to the same extent as with the nasal sprays containing oxymetazoline. The authors concluded that long-term use of oxymetazoline induces a sensation of nasal stuffiness, which may be due to unconscious exaggeration of the degree of nasal stuffiness, induced nasal hyperreactivity, or a combination of both. These factors are probably the main reasons for the prolonged use of nasal decongestive sprays and the development of rhinitis medicamentosa. Benzalkonium chloride induces mucosal swelling, which explains why the presence of this preservative in a decongestant spray aggravates rhinitis medicamentosa.

Clinical and rhinostereometric assessment of nasal mucosal swelling during histamine challenge.

The correlation between the subjective sensation of nasal stuffiness and nasal mucosal swelling measured with rhinostereometry during histamine challenge was studied in 13 healthy subjects. To permit a study of the entire range from decongestion to maximal congestion, the mucosa was pre-treated with a local vasoconstrictor 1 h before it was challenged with eight doses of increasing concentrations of histamine applied to one side of the nose. Ten minutes after each application, the subject estimated stuffiness on the challenged side, using a 100 mm visual analogue scale. The amount of mucosal swelling was measured with rhinostereometry. In 12 of 13 individuals and in the group as a whole, there was a strong positive correlation between a feeling of nasal stuffiness and the degree of mucosal swelling with this nasal provocation model (R = 0.59; P < 0.001).