Stefan Heilmann

A new method for comparing orthonasal and retronasal olfaction

Odors seem to be perceived differently when presented ortho- or retronasally. In this study, stimuli of controlled concentration and duration were applied in either the anterior nasal cavity or epipharynx by means of air-dilution olfactometry. Stimulus concentration was monitored in the olfactory cleft. In Experiment 1, odor thresholds to a food (chocolate) and a nonfood (lavender) odor were lower for orthonasal, compared with retronasal, stimulation. In Experiment 2, intensity ratings to suprathreshold odor concentrations were significantly higher for orthonasal than for retronasal stimulation with hydro- hydrogen sulfide, but not phenyl ethyl alcohol. Accordingly, amplitudes and latencies of olfactory event-related gen potentials to retronasal stimuli were found to be smaller and prolonged, respectively. This indicates differential processing of olfactory stimuli presented through the retronasal or orthonasal routes. )

Local and systemic administration of corticosteroids in the treatment of olfactory loss.

Background The aim of this study was to evaluate the benefit of patients with olfactory dysfunction from local (group A) or systemic (group B) administration of corticosteroids. Methods This unblinded study was conducted at a smell and taste outpatient clinic of an institutional referral center. Patients with olfactory loss after infections of the upper respiratory tract, patients with apparent sinonasal disease, and patients suffering from “idiopathic” smell loss were included. Effects of mometasone nasal spray, administered for 1–3 months, were studied in 37 patients. In addition, effects of oral prednisolone were analyzed in 55 patients who received decreasing doses over 21 days, starting with a dose of 40 mg. Olfactory function before and after treatment was measured. Results Although odor identification scores tended to increase (p = 0.05), mometasone nasal spray did not significantly improve olfactory function, when looking at the entire group of patients or when analyzing the three diagnostic categories separately. In contrast, after systemic administration of corticosteroids, improvement of olfactory function was seen over all diagnostic categories (p < 0.001). Interestingly, olfactory function also improved in patients diagnosed with olfactory loss after upper respiratory tract infection (p = 0.05) and in patients initially diagnosed with “idiopathic” olfactory dysfunction (p = 0.008). Conclusion In many patients, local application of corticosteroids appears to have little or no positive effect on olfactory dysfunction, especially when considering long-term changes. Duration of disease, the patients age/sex, or the presence of parosmia does not appear to predict the response to therapy with corticosteroids.

Dual capacity of a human olfactory receptor

We thank B.W. Ache, J.A. Riffell, and R.K. Zimmer for comments and discussion. This research was supported by the Heinrich and Alma Vogelsang Stiftung.

Lipoic Acid in the Treatment of Smell Dysfunction Following Viral Infection of the Upper Respiratory Tract

Objectives/Hypothesis The study aimed to investigate the potential therapeutic effects of α‐lipoic acid in olfactory loss following infections of the upper respiratory tract. Possible mechanisms of actions include the release of nerve growth factor and antioxidative effects, both of which may be helpful in the regeneration of olfactory receptor neurons.

Responsiveness of human nasal mucosa to trigeminal stimuli depends on the site of stimulation

There is evidence that functionally different areas can be distinguished within the nasal mucosa with regard to stimulation site and stimulus properties. The aim of the present study was the comparison of electrophysiological and psychophysical measures obtained in response to mechanical and chemosomatosensory stimulation of two different regions of the nasal mucosa. A total of 40 volunteers participated in this study (age range 21-36 years). Chemosomatosensory event-related potentials (ERPs) were recorded using gaseous CO2 as stimulant, while somatosensory ERPs were recorded in response to intranasal mechanical stimuli (air puffs). Stimuli were released to the anterior portion and to the posterior portion of the nasal cavity. A significant interaction between stimulus properties and site of stimulation could be detected after analysis of ERP parameters and intensity ratings. Thus, the chemosensory stimulus was perceived as stronger in the anterior portion of the nasal cavity whereas this was not the case for mechanosensory stimuli. In addition, mechanosensory stimuli were found to evoke ERPs with shorter latencies. These results underline the idea that the respiratory mucosa should not be seen as a homogeneous tissue. It exhibits varying sensitivities to trigeminal stimulation depending on stimulus quality and site of stimulation. Hence, perception of chemosensory stimuli seems to be most accurate in the anterior portion of the nasal cavity, while sensitivity to mechanical stimuli appears to be highest in the posterior portion. In addition, these differences within the respiratory mucosa may contribute to differences in the perception of orthonasal and retronasal odorous stimulation.

Clinical presentation of qualitative olfactory dysfunction

Many patients with olfactory dysfunction not only experience quantitative reduction of olfactory function, but also suffer from distorted olfactory sensations. This qualitative dysfunction is referred to as parosmia (also called “troposmia”) or phantosmia, with the major difference that distorted olfactory sensations are experienced in the presence or absence of an odor, respectively. Our clinical observations corroborate the literature in terms of a general underestimation of the incidence of olfactory distortions. Based on selected cases we try to show that olfactory distortions exhibit a large variance in their clinical appearance. Further, emphasis is placed on the fact that only a detailed and directed history of the patient can provide cues to the correct diagnosis.

Immunohistochemical distribution of galectin-1, galectin-3, and olfactory marker protein in human olfactory epithelium.

Abstract The expression pattern of galectin-1 and galectin-3 in the human olfactory epithelium was investigated in relation to olfactory marker protein (OMP) using confocal laser immunofluorescence in human specimens and postmortem biopsies. OMP expression was found in olfactory receptor neurons (ORNs) in the olfactory mucosa and in fibers of the olfactory nerve crossing the submucous connective tissue. Galectin-1 was expressed in both the connective tissue of the nasal cavity and in the basal layer of the olfactory epithelium. In contrast, galectin-3 expression was limited to cells of the upper one-third of the olfactory epithelium. Expression of galectin-3 occurred in a subset of OMP-positive cells. However, between areas of galectin-1 and galectin-3 expression in the lower and upper portion of the epithelium, OMP-positive ORNs did not stain for both galectins. Considering the potential role of galectin-1 and galectin-3 in cell differentiation and maturation, the differential localization of galectins in the olfactory epithelium appears to be consistent with a significant role of these molecules in the physiological turnover of ORNs.

Numerical simulation strategies and test setup for resistance spot welding process with motion overlay

The continuing trend of lightweight construction within the industry requires joining methods for lightweight materials, such as aluminium alloys, that provide a safe and reliable result. One of these processes is resistance spot welding. Its high level of automation and efficiency lead to being one of the most widely used joining methods. The current problem in resistance spot welding of aluminium alloys is the high wear of the electrodes. One reason is the insulating effect of the aluminium oxide layer. The high electrical resistance of the oxide results in local temperature rise and an increased wear on the electrodes. In the extreme, after less than 100 spot welds, the process reliability is no longer guaranteed. A way to reduce the wear is the mechanical destruction of the oxide layer. One possibility is to rotate the welding gun and thus the electrodes around the z-axis, as KUKA’s RoboSpin realizes it.Another approach is currently investigated at Technische Universität Dresden. The focus is on frictionless and frictional movement of the electrode in the form of rotations around the y-axis and movement in the x-direction. For this purpose, a new experimental setup has been developed, which provides all the required degrees of freedom. To gain a better insight into the processes and the contexts of action, simulation models are created based on the finite element method with ANSYS multi-physics and implemented as a network model in MATLAB/Simulink. This paper introduces the new process kinematics, describes the experimental setup and shows first simulation results to perform proof of concept and model verification.