Influence of environmental temperature on human nasal mucosa

New insights into the variability of upper airway morphology in modern humans

The biological adaptation of the human lineage to its environment is a recurring question in paleoanthropology. Particularly, how eco-geographic factors (e.g., environmental temperature and humidity) have shaped upper airway morphology in hominins have been subject to continuing debate. Nasal shape is the result of many intertwined factors that include, but are not limited to, genetic drift, sexual selection, or adaptation to climate. A quantification of nasal airway (NA) morphological variation in modern human populations is crucial to better understand these multiple factors. In the present research, we study 195 in vivo CT scans of adult individuals collected in five different geographic areas (Chile, France, Cambodia, Russia, and South Africa). After segmentation of the nasal airway, we reconstruct 3D meshes that are analyzed with a landmark-free geometric morphometrics method based on surface deformation. Our results highlight subtle but statistically significant morphological differences between our five samples. The two morphologically closest groups are France and Russia, whose NAs are longer and narrower, with an important protrusion of the supero-anterior part. The Cambodian sample is the most morphologically distinct and clustered sample, with a mean NA that is wider and shorter. On the contrary, the Chilean sample form the most scattered cluster with the greatest intra-population variation. The South African sample is morphologically close to the Cambodian sample, but also partially overlaps the French and Russian variation. Interestingly, we record no correlation between NA volume and geographic groups, which raises the question of climate-related metabolic demands for oxygen consumption. The other factors of variation (sex and age) have no influence on the NA shape in our samples. However, NA volume varies significantly according both to sex and age: it is higher in males than in females and tends to increase with age. In contrast, we observe no effect of temperature or humidity on NA volume. Finally, we highlight the important influence of asymmetries related to nasal septum deviations in NA shape variation.

Management of inferior dislocation of a StopLoss Jones tube after conjunctivodacryocystorhinostomy

Persistent epiphora significantly worsens one's quality of life. A commonly known method of treatment of complete obstruction of the lacrimal canaliculi is conjunctivodacryocystorhinostomy with placement of a glass Jones tube. Unfortunately, the use of such a prosthesis of the lacrimal tract often results in certain complications, the most frequent of which include extrusion or superior and inferior migration. For the last several years, a modified version of the Jones tube-the StopLoss Jones tube (SLJT)-has been available. It almost eliminates the possibility of extrusion. However, inferior migration still remains an important problem. When that happens, it is necessary to proceed surgically. In this paper, we describe an endoscopically-guided technique of management of an inferiorly dislocated SLJT.

Relationship between Subjective Nasal Stuffiness and Nasal Patency Measured by Acoustic Rhinometry

Nasal geometry measured by acoustic rhinometry was compared with the subjective sensation of nasal stuffiness in healthy subjects before and after provocation with histamine. The correlation was poor at rest, but it was significant after histamine provocation in children and adults. It is easier to find a relationship between subjective and objective nasal obstruction after inducing congestion.

The Effect of Topical Xylometazoline on the Mucosal Temperature of the Nasal Septum

Background

The purpose of this study was to determine the short-term influence of the α2-adrenoreceptor agonist xylometazoline on the nasal mucosal temperature.

Methods

Thirty healthy subjects were enrolled into the study. Fifteen of these subjects got xylometazoline and 15 subjects, matched to age, got saline solution as control. A miniaturized thermocouple was used for continuous detection of the septal mucosal temperature without interruption of nasal breathing before and after application of nose spray.

Results

In the anterior nasal segment, the mucosal temperatures before decongestion were significantly higher than after decongestion (p < 0.05). These changes could not be found in the control group after saline solution. The mean end-expiratory mucosal temperatures were significantly higher than the end-inspiratory ones in both study groups (p < 0.005).

Conclusions

The reduction of the nasal mucosal blood flow because of vasoconstriction and the increase of the nasal cavity volume after decongestion with xylometazoline seem to cause a significant decrease of the septal mucosal temperature in the anterior nasal segment. This might be one possible causative factor of the common symptom of the “dry nose” in patients with nasal decongestant abuse.

Low Temperature Decreased Tension in Isolated Hypertrophic Human Nasal Mucosa

Background

The purpose of this study was to evaluate the effect of low temperature on basal tension in isolated hypertrophic human nasal mucosa with or without α1-agonist stimulation.

Methods

A tissue bath for isolated nasal mucosa was used. Tension in strips of human turbinate mucosa that were untreated and treated with an α1-adrenoreceptor agonist, methoxamine (10 μM), was recorded continuously in a stepwise manner in temperatures that varied from 37 to 10°C.

Results

The changes of tension in the human nasal mucosa were found to be temperature-dependent in both untreated and treated tissues, with tension decreasing to 48.6% at 10°C in comparison with 100% at 37°C in the untreated group, the presence of methoxamine (10 μM) had minimal effect.

Conclusion

Low temperature induced a rapid and reproducible relaxation in isolated hypertrophic human nasal mucosa that was not affected by the presence of the α1-agonist methoxamine (10 μM).

The association between mid-facial morphology and climate in northeast Europe differs from that in north Asia: Implications for understanding the morphology of Late Pleistocene Homo sapiens

The climate of northeastern Europe is likely to resemble in many ways Late Pleistocene periglacial conditions in Europe, but there have been relatively few studies exploring the association between climate and morphology in the mid-face of modern northeastern European populations. To fill this gap, we sampled 540 male skulls from 22 European and Near Eastern groups, including 314 skulls from 11 populations from northeastern Europe, to test for possible climate-morphology association at the continental scale. Our results found a moderate and highly significant association (R = 0.48, p = 0.0013, Mantel test) between sets of 23 mid-facial measurements and eight climatic variables. A partial least squares analysis revealed this association to be mostly driven by differences between groups from northeastern Europe and populations from the Mediterranean and the Caucasus. Matrices of between-group genetic distances based on Y-chromosome and mtDNA markers, as well as cranial non-metric and geographic distance matrices, were used to control for the possible influence of shared population history. Irrespective of which measure of neutral between-population distances is taken into account, the association between cranial variables and climate remains significant. The pattern of association between climate and morphology of the mid-face in western Eurasia was then compared to that in east and north Asia. Although differences between the two were found, there were also similarities that support existing functional interpretations of morphology for the bony parts of the upper airways. Last, in a preliminary analysis using a reduced set of measurements, mid-facial morphology of several Upper Paleolithic European Homo sapiens specimens was found to be more similar to groups from northern and northeastern Europe than to southern European populations. Thus, the population of northeastern Europe rather than east and north Asian groups should be used as a model when studying climate-mediated mid-facial morphology of Upper Paleolithic European H. sapiens.

Identification of the cold receptor TRPM8 in the nasal mucosa

BACKGROUND

The transient receptor potential channel melastatin 8 (TRPM8) has been proposed to be a cold receptor. However, its distribution and physiologic role in the nose is not yet fully explored.

OBJECTIVE

We investigated the expression of TRPM8 in human nasal mucosa and its function when using the TRPM8 agonist.

METHODS

Immunohistochemistry was used to study TRPM8 receptors in the nasal mucosa from patients with and those without allergic rhinitis (AR). By using isometric contraction studies, we also tested the effectiveness of the TRPM8 agonist menthol on nasal mucosa. Changes in nasal mucosal contractility in response to the application of the adrenergic agent methoxamine were also measured. We explored the effect of menthol on electrical field stimulation (EFS) induced nasal mucosal contractions.

RESULTS

TRPM8 immunoreactivity was present principally in the nasal cilia, epithelium, and subepithelium around the glands. Except for nerve fibers, no obvious TRPM8-immunoreactive cells were detected in connective tissues. The immunoreactivity revealed no significant difference between patients with AR and those without AR. Adding menthol had a negligible effect on the basal tension of the nasal mucosa, but higher doses of menthol had a significant spasmolytic effect on nasal mucosa precontracted with methoxamine. Menthol inhibited the spike contraction induced by EFS, even at low doses.

CONCLUSIONS

The finding of the TRPM8 immunoreactivity underlines the important physiologic role of the nose in temperature regulation, both in patients with allergy and those without allergy. Isometric contraction studies demonstrate the role of TRPM8 in regulating nasal patency and airway resistance. The antiadrenergic effect of menthol showed an effect apparently opposite that of clinical observations, that we usually feel decongested after menthol inhalation. The underlying mechanisms deserve further investigation, and the TRPM8 antagonists deserve consideration for treatment of rhinitis in a therapeutic trial.

Comparison of nasalance scores obtained with the nasometers 6200 and 6450

OBJECTIVE

The study had the goal of comparing the new Nasometer 6450 to the older model 6200 using synthetic test sounds and control participants. A particular focus of the investigation was on the test-retest variability of the instruments.

MATERIALS AND METHODS

The Nasometers 6200 and 6450 were compared using square wave test sounds. Six repeated measurements of oral, balanced, and nasal test stimuli were recorded from 25 female participants over an average of 35 days.

RESULTS

The synthetic test sounds demonstrated that the two nasometers obtained similar results for a range of frequencies. The results for the clinically normal participants revealed that nasalance scores from the two instruments were within 1-2 points, depending on the test sentence. Variability in scores increased with the proportion of nasal consonants in the sentence. Test-retest variability was between 6 and 8 points for more than 90% of the participants. Participants with higher nasalance scores for oral stimuli had higher between-session variability.

CONCLUSIONS

The Nasometers 6200 and 6450 should yield comparable results in clinical practice. Depending on the phonetic content of the test materials, clinicians should allow for a 6- to 8-point between-session variability when interpreting nasalance scores.

Numerical simulation and nasal air-conditioning

Heating and humidification of the respiratory air are the main functions of the nasal airways in addition to cleansing and olfaction. Optimal nasal air conditioning is mandatory for an ideal pulmonary gas exchange in order to avoid desiccation and adhesion of the alveolar capillary bed. The complex three-dimensional anatomical structure of the nose makes it impossible to perform detailed in vivo studies on intranasal heating and humidification within the entire nasal airways applying various technical set-ups. The main problem of in vivo temperature and humidity measurements is a poor spatial and time resolution. Therefore, in vivo measurements are feasible only to a restricted extent, solely providing single temperature values as the complete nose is not entirely accessible. Therefore, data on the overall performance of the nose are only based on one single measurement within each nasal segment. In vivo measurements within the entire nose are not feasible. These serious technical issues concerning in vivo measurements led to a large number of numerical simulation projects in the last few years providing novel information about the complex functions of the nasal airways. In general, numerical simulations merely calculate predictions in a computational model, e.g. a realistic nose model, depending on the setting of the boundary conditions. Therefore, numerical simulations achieve only approximations of a possible real situation. The aim of this review is the synopsis of the technical expertise on the field of in vivo nasal air conditioning, the novel information of numerical simulations and the current state of knowledge on the influence of nasal and sinus surgery on nasal air conditioning.

Nasal Physiological Reactivity of Subjects with Nonallergic Rhinitis to Cold Air Provocation: A Pilot Comparison of Subgroups

Background

Noninfectious nonallergic rhinitis (NINAR) is characterized by self-reported hyperreactivity to nonspecific physical or chemical stimuli. The relationship between these two classes of triggers is not well established, however. We compared NINAR subjects with predominantly physical or chemical triggers versus normal controls with respect to subjective (symptomatic) and objective (obstructive) responses to cold, dry air challenge.

Methods

We studied 14 NINAR subjects and 10 normal controls. Exposures consisted of 15 minutes of cold dry air (0°C/5% RH) or warm moist air (25°C/50% RH) on two separate days a week apart. Subjects rated symptoms using visual analog scales and had their nasal airway resistance measured at baseline, immediately after, and at 15-minute intervals for 1 hour postexposure.

Results

The majority of NINAR subjects reported physical triggers as more troublesome than chemical. Immediately postprovocation, the mean net proportional change in nasal airway resistance from baseline was +0.18 in NINAR (physical), +0.05 in NINAR (chemical), and –0.01 in control subjects (NS). However, a pooled linear regression by number of physical triggers (0–5) revealed a 7.5% increase in cold air–induced nasal airway resistance per trigger reported (p < 0.05). Similarly, raising the criterion number of physical triggers from ≥1 to ≥2 also distinguished NINAR subjects from controls in a bivariate analysis.

Conclusion

Either considering self-reported physical triggers as a continuous scale (0–5) or requiring more physical triggers (≥ 2 rather than ≥1) to define NINAR successfully predicts objective nasal reactivity to cold air provocation.

Low temperature results in decreased tension in decellularized human nasal mucosa

BACKGROUND

Cooling may induce nasal obstruction. In our previous study, we showed low temperature induced a rapid relaxation of isolated human nasal mucosa and it was independent of vasoconstriction. The aim of this study was to elucidate the mechanism responsible for such findings.

METHODS

Nasal mucosa strips were prepared from inferior turbinate samples. Decellularization of human nasal mucosa was achieved by treatment with sodium dodecyl sulfate 0.1% for 15 hours at 37 degrees C in a shaking water bath. Then, the effect of cooling (37-10 degrees C) on the isometric tension change of decellularized nasal mucosa was evaluated. In addition, the presence of elastic fibers within the nasal mucosa was identified in both histological section and scanning electron microscope.

RESULTS

Results indicated cooling induced a relaxation response of isolated decellularized human nasal mucosa and it was similar to that of intact nasal mucosa. The elastic fibers formed in wavy lines and were distributed throughout the submucosal layer.

CONCLUSION

Cooling induced a similar relaxation response both in the absence or in the presence of cellular components in isolated human nasal mucosa, suggesting that this response is mediated by the abundant extracellular matrix.

Simultaneous in vivo measurements of intranasal air and mucosal temperature

Nasal cavity volume and blood temperature along the nasal airways, reflecting the mucosal temperature, are considered to be the most important predictors of nasal air conditioning. The purpose of this study was to simultaneously in vivo measure intranasal air as well as mucosal temperature for the first time. Fifteen healthy subjects were enrolled into the study. Two combined miniaturized thermocouples were used for simultaneous recording of intranasal air and mucosal temperature within the anterior turbinate area close to the head of the middle turbinate without interruption of nasal breathing. The highest air and mucosal temperature values were detected at the end of expiration, the lowest values at the end of inspiration. The difference was statistically significant (P < 0.05). The mean mucosal temperature ranged from 30.2 +/- 0.9 to 32.2 +/- 0.8 degrees C. The mean air temperature ranged from 28.5 +/- 1.2 to 34.1 +/- 0.7 degrees C. The mean differences between air and mucosal temperature were 1.7 +/- 0.5 degrees C after inspiration and 1.9 +/- 0.7 degrees C after expiration. Simultaneous measurements of intranasal air and mucosal temperature are practicable. The detected temperature gradient between air and mucosa confirm a relevant heat exchange during inspiration and expiration. This gradient between air and mucosa is obligatory for heat and water exchange to ensure adequate nasal air conditioning.

Effect of cooling on electrical field stimulation and norepinephrine-induced contraction in isolated hypertrophic human nasal mucosa

BACKGROUND

Exposure to cold causes cutaneous vasoconstriction to reduce body heat loss, while the nasal cavity warms up the inspired cold air. This suggests cooling might evoke a different response in nasal mucosa blood vessels than in cutaneous blood vessels. Thus, the aim of this study was to evaluate the effect of cooling (to 24 degrees C) on the vascular response of isolated nasal mucosa.

METHODS

An in vitro isometric contraction of nasal mucosa excised from patients suffered from chronic nasal congestion was continuously recorded. Either electrical field stimulation (EFS) or exogenous norepinephrine (NE) was applied to the turbinate mucosa strip at 37 and 24 degrees C, and the influence of cooling (to 24 degrees C) was evaluated.

RESULTS

EFS (1, 2, 4, and 8 Hz) produced frequency-dependent contractions at 37 and 24 degrees C. Cooling did not alter the magnitude but significantly prolonged the duration of EFS-induced contraction. Exogenous NE (10(-8) to 10(-4) M) produced concentration-dependent contractions at 37 and 24 degrees C. Cooling significantly enhanced the contractile responses evoked by NE between 3 x 10(-6) and 1 x 10(-4) M.

CONCLUSION

Cooling (to 24 degrees C) prolonged the EFS-induced and enhanced NE (3 x 10(-6) to 1 x 10(-4) M)-induced contraction of isolated human nasal mucosa.

Efficacy of ice packs in the management of epistaxis

There are no uniformly accepted criteria for the management of epistaxis. The usefulness of ice application in the treatment of epistaxis as a first aid method is not generally accepted, but is widespread. In order to evaluate the effect of cold application on the blood vessels of the nasal mucosa, their blood flow and blood content were investigated on 56 healthy volunteers before and after exposure to cold in the neck area. Nasal mucosal microcirculatory blood flow was measured directly by non-invasive laser Doppler flowmetry in Kiesselbach's area. Changes in the nasal mucosal blood content were estimated using a conventional computer-aided rhinomanometer by measuring alterations in nasal airflow. After ice application in the neck area, no statistically significant effects on the blood vessels of the nasal mucosa were seen. These results do not support the usefulness of this manoeuvre in the treatment of epistaxis.

Nasal mucosal temperature during respiration

One of the most important functions of the nose is heating the inspiratory air. The aim of the present study was to measure nasal mucosal temperature at defined intranasal sites during respiration, without interruption of nasal breathing. A total of 15 healthy volunteers was included in the study. A miniaturized thermocouple was used for continuous detection of the septal mucosal temperature in the nasal vestibule, the nasal valve area, the anterior turbinate area and the nasopharynx during respiration. The highest temperature values were measured at the end of expiration, the lowest values at the end of inspiration with a statistically significant difference (P < 0.005). Mean mucosal temperature ranged from 30.2 +/- 1.7 degrees C to 34.4 +/- 1.1 degrees C. Statistically there were significant differences between the detection sites during inspiration and expiration (P < 0.05). In our study, the temperature values of the nasal mucosa depend on the intranasal detection site and the respiratory cycle. We therefore conclude that whenever data of nasal mucosal temperature are published, it is absolutely essential to describe the precise site of detection and to give information about the time of detection in the respiratory cycle.

Supine position decreases the ability of the nose to warm and humidify air

We tested the hypothesis that decreasing nasal air volume (i.e., increasing nasal turbinate blood volume) improves nasal air conditioning. We performed a randomized, two-way crossover study on the conditioning capacity of the nose in six healthy subjects in the supine and upright position. Cold, dry air (CDA) was delivered to the nose via a nasal mask, and the temperature and humidity of air were measured before it entered and after it exited the nasal cavity. The total water gradient (TWG) across the nose was calculated and represents the nasal conditioning capacity. Nasal volume decreased significantly from baseline without changing the mucosal temperature when subjects were placed in the supine position (P < 0.01). TWG in supine position was significantly lower than that in upright position (P < 0.001). In the supine position, nasal mucosal temperature after CDA exposure was significantly lower than that in upright position (P < 0.01). Our data show that placing subjects in the supine position decreased the ability of the nose to condition CDA compared with the upright position, in contrast to our hypothesis.

Elevation of nasal mucosal temperature increases the ability of the nose to warm and humidify air

The nose functions to warm and humidify inspired air. The factors that influence these functions have been studied to a limited degree. We have developed a method for measuring the temperature and relative humidity of the air before and after nasal conditioning to study nasal function. In this experiment we studied the effects of raising the mucosal surface temperature by immersion of the feet in warm water. Six subjects (avg. age = 27.0 years) were randomized to immersion of the feet in 30 degrees C and 40 degrees C water. The nasal mucosal temperature increased significantly from the 32.2+/-1.3 degrees C during immersion in the 30 degrees C water to the 33.1+/-1.2 degrees C during immersion in 40 degrees water (p < 0.05). No significant difference in nasal volume was noted between the 30 degrees (17.8+/-4.5 cc) and the 40 degrees (17.7+/-5.3 cc) immersions. There was a significant increase in the conditioning capacity of the nose (as measured by total water content of inspired air) in response to cold-air challenge during the 40 degrees immersion (1669+/-312 mg water) when compared to the 30 degrees immersion (1324+/-152 mg water). From these data we deduce that warming of the nasal mucosa improves the ability of the nose to condition inspired air without a significant change in the volume of the nasal cavity.

Nasobronchial relationship after cold air provocation

Provocation with cold air in the nose causes broncho-obstruction while warm air causes bronchodilation in patients with asthma, but not in healthy subjects. These findings have suggested the existence of a nasobronchial reflex. The present study aimed to block this effect and evaluate the mechanisms underlying the effect on lung function after cold stimulation of the nose. Lung function, as measured with specific conductance and forced expiratory flow, was reduced after cold stimulation of the nose, but this effect could not be blocked by anesthetizing the nose or by inhaling an anti-cholinergic drug before the provocation. These results confirm the presence of a nasobronchial relationship, but not of a nasobronchial reflex.

Reference values for acoustic rhinometry in subjects without nasal symptoms

Reference values for acoustic rhinometry are presented from 334 individuals without nasal symptoms between 4 years and 61 years old. There was a significant correlation between the minimal cross-sectional area (MCA) and nasal volume. Although the reproducibility of the method was good, the MCA varied widely. MCA correlated weakly to weight, height, age, and body mass index. Our data suggest that acoustic rhinometry is valuable for inter-individual comparisons.

Effects of nasal-airway volume and body temperature on intranasal chemosensitivity

Interrelations between intranasal detection sensitivity for odor (H2S) and pain (CO2), nasal-airway volume (acoustic rhinometry), and body temperature were studied in young, healthy men across the diurnal cycle. The results showed a weak but statistically significant negative correlation between nasal volume and odor threshold and a weak but positive correlation between body temperature and odor threshold.

An evaluation of nasal response following different treatment regimes of oxymetazoline with reference to rebound congestion

This was a randomized, double-blind vehicle controlled study aimed at investigating the effects on nasal function of 7 days treatment with the topical decongestant oxymetazoline (0.05% w/v). Fifty healthy volunteers took part in the study and these were randomly allocated to three treatment groups (i) daily oxymetazoline (b.i.d. 150 microliters per nostril) (ii) intermittent oxymetazoline, with oxymetazoline being substituted for vehicle at the morning doses on days 1, 3, and 7; and (iii) daily vehicle (b.i.d. 150 microliters per nostril). The nasal airway was assessed by measurement of nasal airway resistance (NAR) using posterior rhinomanometry, subjective scaling of nasal patency by means of a visual analogue scale (VAS), and clinical visual examination. On days 1, 2, 3, and 7, NAR and VAS measurements were obtained before the morning dose and up to 6 hours after dosing; clinical visual examinations were also performed before dosing on these days. NAR and VAS measurements were also made following withdrawal of treatment on Days 8 and 9. Nonparametric analysis of the results showed that therapeutic tolerance to oxymetazoline did not develop over the 7-day treatment period, and visual examination of the nasal mucosa failed to find significant evidence of rhinitis. Evidence of rebound nasal congestion was found following 3 days of oxymetazoline treatment, with baseline NAR within the daily and intermittent oxymetazoline groups being significantly greater on Day 3 compared to Day 1 (p < 0.05). However, there was a trend toward increasing baseline NAR in the vehicle group over the course of the study, suggesting that the vehicle may have contributed to the rebound congestion. Following the withdrawal of treatments, only the intermittent oxymetazoline group had significantly higher NAR on Days 8 and 9 compared to Day 1 (p < 0.05). Subjective VAS measurements generally followed trends in NAR.

Autonomic reflexes and non-allergic rhinitis

Functions traditionally ascribed to the nose include warming, humidification, and filtration of inspired air prior to its passage to the lower respiratory tract. The nose thus conditions inspired air, making it suitable for pulmonary gas exchange. In order to carry out these functions, the nose is subject to a complex series of reflexes mediated via the autonomic nervous system. The effector tissues are the nasal blood vessels and glands. Perennial non-allergic rhinitis may be divided into two types based on the presence or absence of eosinophilia in nasal secretions. Much circumstantial evidence suggests that non-eosinophilic non-allergic rhinitis (NENAR) may be a disease of autonomic imbalance. In a series of studies carried out at the University of Liverpool, patients with perennial non-allergic rhinitis, and NENAR in particular, were found to have qualitative and quantitative abnormalities in their nasal response to various stimuli as manifested by changes in nasal patency. The nasal response to axillary pressure is much reduced in NENAR patients compared with normal controls, and the normal decrease in nasal resistance in response to standing is abrogated. Isometric exercise has little effect in normal subjects, but those with NENAR demonstrate an increase in nasal resistance. A similar effect is seen in response to the cold pressor test. Of great importance for therapy is the effect of topical fluticasone propionate in patients with NENAR. Treatment normalizes the damaged nasal reflexes seen in this condition, whereas placebo has no effect. However, abnormalities in other non-nasal autonomic reflexes (systemic parameters) are not affected by treatment.

Lack of effect of hot, humid air on response to nasal challenge with histamine

We have previously shown that whole body exposure of human subjects to environmental conditions of 37 degrees C and 90% relative humidity (RH) prior to and during nasal challenge with antigen decreases the early response. In this study, we evaluated 1) whether the decreased responses observed resulted from decreased end organ sensitivity to histamine and 2) whether the effect of hot, humid air persisted after the subject exited the hot, humid environment. Ten asymptomatic seasonal allergic subjects and 11 nonallergic subjects were randomized to environmental chamber conditions of either 20 degrees C, 30% RH or 37 degrees C, 90% RH for 1 hour prior to and during performance of a nasal challenge with histamine. Twenty-two hours after exiting the environmental chamber, the allergic subjects were challenged with antigen. During both chamber conditions, histamine challenge was associated with a significant increase in all measured parameters compared to sham challenge, except for the sensations of pruritus and congestion. The response to histamine challenge was not different under the two experimental conditions or between allergic and nonallergic subjects. Following both exposure conditions, allergen challenge was associated with an increase in all measured parameters compared to sham challenge, with no significant difference between the two conditions. Exposure to 37 degrees C, 90% RH minimally affects the response to nasal challenge with histamine, and thus, the previously reported decreases in the early nasal response to antigen may primarily result from reduction in mast cell activation. The effect on antigen does not persist 22 hours after exposure.

Nasal reaction to changes in whole body temperature

The changes in nasal patency following a 1.5 degrees C decrease or increase in whole body temperature were measured in 8 healthy young males, during and after 30 min of immersion in a 15 degrees C cold or a 40 degrees C warm bath, breathing air at the same temperature, in a cross-over experimental design. The nasal reactions were traced by consecutive measurements of changes in nasal cavity volumes by acoustic rhinometry. Swelling of the mucosa during cooling and an almost maximal shrinkage of the mucosa during heating were indicated by respectively a decrease and an increase in nasal cavity volumes. The reactions were determined predominantly by the whole body thermal balance, but were also influenced by the temperature of the inhaled air, either enhanced, reduced or temporarily reversed. The greatest change occurred in the nasal cavity, left or right, which differed most from the final state at the beginning of exposure due to the actual state of nasal cycle.

Variation in human nasal height and breadth

It has been suggested that the long-standing association of variability in the human nasal index [100 x (nasal breadth)/(nasal height)] with climatic variation is spurious evidence for natural selection in humans (Hoyme, 1965; St. Hoyme and Işcan, 1989). The argument is based principally on the observation that nasal height is globally more variable than nasal breadth, with nasal breadth thus contributing little to variation in the index. This argument does not take into account the confounding effect of absolute size of these variables on their variances. In this study we compare the intrinsic variation in skeletal nasal height and breadth within and among 26 mixed-sex populations (N = 2,408) at globally diverse localities (Howells, 1989), using 2 x 2 variance-covariance matrices of the logarithmically transformed variates. Hypothesis tests for homogeneity of matrices and equal-variance/equal-covariance indicate that the intrinsic variation in nasal breadth is greater than that for nasal height within populations, and that nasal breadth and nasal height exhibit equivalent intrinsic variation among populations. The argument that nasal breadth contributes little to the world-wide variation in the human nasal index is rejected. Given our present understanding of nasal physiological morpho-function, these results support, but do not demonstrate, an adaptive role for human nasal index variation. Promising methods for elucidating natural selection on human nasal form are suggested.

Dermal blood flow after local challenges with allergen, histamine, bradykinin and compound 48/80

Blood flow was determined in weal and flare reactions and in late dermal reactions after skin-prick tests with allergen, histamine, bradykinin and compound 48/80 in pollen-allergic subjects. Local blood flow was measured with laser Doppler flowmetry intermittently for up to 48 hr at three distances from the prick centre (2 mm; weal, 15 mm; flare and 30 mm). Continuous recordings were also made in the weal area after challenge with bradykinn and compound 48/80. The size of the induced weal and flare area of all the substances and the late phase after allergen was determined using digitized planimetry. Furthermore, simultaneous determinations of local dermal temperature and blood flow in the weal and flare site were performed intermittently for 6 hr after allergen and histamine challenges. There was a dose-dependent and distance-related increase in blood flow for all the substances tested. The blood flow in the 2-mm registrations had normalized 20 min after bradykinin, 1.5-2 hr after histamine and 3 hr after compound 48/80, while allergen induced a continuous increase in blood flow for more than 24 hr. The area of the weal and flare reaction was dose related for all substances, and a similar dose-dependent increase was noted for the observed dermal late-phase reactions present after allergen. The local temperature after challenge with allergen and histamine was also increased in a distance-dependent manner. These studies suggest that laser Doppler flowmetry is a sensitive and reproducible method to quantify blood flow changes occurring after skin-prick tests. Different putative mediators or mast cell stimulating substances produce various response profiles, all of which differ from those observed after allergen. Temperature measurements after skin-prick tests seem to follow the observed changes in blood flow as measured with laser Doppler flowmetry, which may be why both techniques might reflect changes in capillary blood flow.

The effect of ice packs upon nasal mucosal blood flow

The effect on nasal mucosal blood flow of ice packs on the forehead and ice packs within the mouth was investigated in 16 healthy subjects. The laser Doppler flowmeter was used to record changes in blood flow to the inferior turbinate, as measured by change in the flux. Ice packs within the mouth produced a significant decrease in nasal mucosal blood flow (p less than 0.05). The average fall was 23% (SEM 5.9) compared with the control measurements. No significant change was recorded following the application of ice packs to the forehead. The results of this study question the scientific rationale behind the use of forehead ice packs in clinical practice.

Decrease in xenon clearance during response to cold, dry air: problems of interpretation

In order to increase our understanding of the nasal response to cold, dry air (CDA), we studied changes in xenon clearance as an indicator of nasal blood flow. Eight individuals previously shown to respond to CDA had measurements of xenon clearance made in the left inferior turbinate before, during, and after a 15-minute exposure to either CDA (-7 degrees C to 0 degrees C, less than 10% relative humidity) or room air. The half-life in seconds for xenon clearance on the day when CDA was inhaled was 56 +/- 6, 41 +/- 5, and 110 +/- 31, before, during, and 10 minutes after challenge, respectively. On the control day, with subjects breathing room air, the equivalent measurements of half-life in seconds were 54 +/- 8, 41 +/- 6, and 42 +/- 4, respectively. Xenon clearance was prolonged significantly (p less than .01) after exposure to CDA during the clinical response. The interpretation of the change in xenon clearance as an indicator of nasal blood flow is discussed.

Priming effect of a birch pollen season studied with laser Doppler flowmetry in patients with allergic rhinitis

Nasal mucosal provocation tests were done on eight patients with seasonal allergic rhinitis before and after a birch pollen season. The effects on nasal microvascular blood flow were detected by means of laser Doppler flowmetry. The patients reacted to the birch pollen provocation with an increase in blood flow. This increase was greater after the pollen season than before, when the same pollen doses were used, indicating a priming phenomenon of the resistance vessels.

Effects of elevated intranasal temperature on subjective and objective findings in perennial rhinitis

The effects of elevated intranasal temperature on symptoms and signs of perennial rhinitis were studied in 78 patients by a double-blind, randomized, placebo-controlled clinical trial. Patients were subjected to two treatments separated by a 1-week interval. Each treatment consisted of three 30-minute sessions, during which the patient's intranasal temperature was raised by inhalation of saturated hot air (42 degrees C to 44 degrees C). Subjective response was recorded on a daily symptom score card during the week following treatment. Nasal patency was determined before and after treatment by measuring maximal nasal expiratory and inspiratory airflow and by measuring the area covered with vapor formed by the exhaled air on a plate. Highly reproducible results were obtained by using these three objective methods. Elevation of intranasal temperature resulted in amelioration of rhinitis symptoms and in objective evidence of increased nasal patency in a significant percentage of patients compared to the placebo-treated group.

Effects of steam inhalation on nasal patency and nasal symptoms in patients with the common cold

The effects of steam inhalation on nasal patency and on nasal symptoms were studied in 62 patients with the common cold by a double-blind, randomized, placebo-controlled clinical trial. Treatment consisted of two 20-minute sessions, during which the patient inhaled saturated, hot (42 degrees to 44 degrees C) air through the nose. The subjective response was recorded by each patient during the week following treatment on a daily symptom score card. Nasal patency was determined before treatment, the following day, and 1 week later by measuring peak nasal expiratory and inspiratory air flow. Highly reproducible results were obtained by using these objective methods. Steam inhalation resulted in alleviation of cold symptoms and increased nasal patency in a significantly higher percentage of patients in the actively treated group than in the placebo-treated group. Possible explanations for the effectiveness of treatment are discussed.

Effects of glypressin on human nasal mucosa

The effect of intravenous and topical glypressin, a triglycyl hormonogen of vasopressin, on the nasal mucosa was evaluated in healthy subjects. A dose-dependent reduction of nasal blood flow resulted from both intravenous and topical glypressin. The effect of the latter in gel form lasted 2 hours. Glypressin was also found to decongest the nasal mucosa. Topical application of glypressin gel might be an alternative to conventional treatment with intranasal packing in nose-bleed.

A comparison between the 133Xe washout and laser Doppler techniques for estimation of nasal mucosal blood flow in humans

Measurements of blood flow in the human nasal mucosa can be performed with 133Xe washout technique and with laser doppler flowmetry. These methods are based on different principles and a comparison of the methods is of interest. For this purpose the 133Xe washout and laser doppler techniques were used to evaluate the effect of topical xylometazoline and noradrenaline on blood flow. Xylometazoline was found to induce a dose-dependent decrease in nasal mucosal blood flow, as registered with both methods. After noradrenaline, no change in blood flow was seen in 133Xe washout measurements, whereas a reduced blood flow was registered with laser doppler flowmetry. It is concluded that the 133Xe washout technique and laser doppler flowmetry reflect blood flow in different parts of the vascular bed in the human nasal mucosa, which means that they complement each other in such investigations.