Artificial Neural Network (ANN) Modeling of Odor Threshold Property of Diverse Chemical Constituents of Black Tea and Coffee

The authors have developed an artificial neural network model using odor threshold (OT) property data for diverse odorant components present in black tea (76 components) and coffee (46 components). The models were validated in terms of both internal and external validation criteria signifying acceptable results. The authors found the significant features controlling the OT property using Mean Absolute Error (MAE)-based criteria in a backward elimination of descriptors, one in each turn. The present results well-corroborated the previously published PLS-regression based chemometric model results.

Olfactory function testing before and after anesthesia

This study aimed to determine whether anesthesia would affect olfactory function. Patients who were admitted for surgical intervention that did not include the nasal cavity and paranasal sinuses were included in this prospective cohort study. Structured medical history was taken from the patients, including the following: age, sex, smoking history, alcohol intake, current medications, and sleep deficits prior to surgery. Before surgery, patients were asked for a self-rating of their olfactory function. Olfactory function was also measured using Sniffin’ Sticks comprising measures of odor threshold, discrimination, and identification. The mean interval between olfactory tests was 6 days (range 3–12 days). Seventy-three patients were included in the study, 34 men and 39 women. Olfactory scores were consistent before and after surgery as indicated by correlative analyses (p < 0.05). Odor thresholds, discrimination, identification, and composite TDI scores did not change significantly, whereas odor identification scores increased (p = 0.011) after surgery. In conclusion, post-operative olfactory scores remained stable. However, identification scores exhibited a slight increase which can be attributed to a retest effect. Overall, the present results indicate that surgery outside of the nasal and paranasal sinus region performed in general anesthesia has no major effect on the sense of smell.

Unilateral Choanal Atresia: Indications of Long-Term Olfactory Deficits and Volumetric Brain Changes Postsurgically

<b><i>Background:</i></b> Very few studies have investigated whether unilateral choanal atresia is associated with permanent olfactory deficits. <b><i>Objective:</i></b> This study aimed to evaluate the olfactory performance of patients with unilateral choanal atresia postsurgically. <b><i>Methods:</i></b> Three patients with unilateral atresia were examined in terms of olfactory performance with the Sniffin’ Sticks test (odor identification, threshold, and discrimination), size of the olfactory bulb, and volumetric brain changes. <b><i>Results:</i></b> All patients demonstrated significantly lower olfactory performance in terms of odor threshold on the same side with the choanal atresia. Grey matter reductions were found ipsilaterally in the hippocampus. <b><i>Conclusions:</i></b> This pilot study indicates that persistent olfactory deficits and volumetric brain changes are present in patients with unilateral choanal atresia.

Symptoms of Depression Change With Olfactory Functions

Olfactory loss is associated with symptoms of depression. The present study, conducted on a large cohort of mostly dysosmic patients, aimed to investigate whether improvement in olfactory performance would correspond with a decrease in depression severity and, if so, to what extent. In 171 participants, we assessed olfactory function and severity of depression before and after an average interval of 11 months, with many patients improving in function. Separate analyses were conducted for a) the whole group of patients and b) the group of dysosmic patients in both classic and Bayesian ways. Student t-test demonstrates that the whole sample improved consistently, especially within the group of dysosmic patients in terms of odor identification, and the dysosmic group also improved in terms of odor threshold and olfactory functions in general. Pearson correlation showed that the increase in olfactory functions corresponded with the decrease in depression severity, particularly in dysosmic patients. To conclude, the present study results indicate that symptoms of depression change with olfactory functions in general and odor identification in particular.

Additivity between Key Odorants in Pig House Air

The verification of odor abatement technologies for livestock production based on chemical odorants requires a method for conversion into an odor value that reflects the significance of the individual odorants. The aim of the present study was to compare the SOAV method (Sum of Odor Activity Values) with the odor detection threshold measured by olfactometry and to investigate the assumption of additivity. Synthetic pig house air with odorants at realistic concentration levels was used in the study (hydrogen sulfide, methanethiol, trimethylamine, butanoic acid, and 4-methylphenol). An olfactometer with only PTFE in contact with sample air was used to estimate odor threshold values (OTVs) and the odor detection threshold for samples with two to five odorants. The results show a good correlation (R2 = 0.88) between SOAV estimated based on the OTVs for panelists in the present study and values found in the literature. For the majority of the samples, the ratio between the odor detection threshold and SOAV was not significantly different from one, which indicates that the OAV for individual odorants in a mixture can be considered additive. In conclusion, the assumption of additivity between odorants measured in pig house air seems reasonable, but the strength of the method is determined by the OTV data used.

Smell and taste in idiopathic blepharospasm

The pathophysiology of blepharospasm is incompletely understood. Current concepts suggest that blepharospasm is a network disorder, involving basal ganglia, thalamus, cortex, and, possibly, the cerebellum. Tracing, imaging, and clinical studies revealed that these structures are also concerned with olfaction and taste. Because of this anatomical overlap, dysfunction of the chemical senses in blepharospasm is expected. Injections of botulinum toxin into the eyelid muscles are the first-line treatment of blepharospasm. Yet, the effects of botulinum toxin on the chemical senses have not been systematically assessed. To contribute to a better understanding of blepharospasm, olfactory and gustatory abilities were assessed in 17 subjects with blepharospasm and 17 age-/sex-matched healthy controls. Sniffin Sticks were used to assess odor threshold, odor discrimination, and odor identification. Results of these three Sniffin Sticks subtests were added to the composite olfactory score. The Taste Strips were applied to assess taste. In an adjacent study, we assessed the sense of smell and taste in eight subjects with blepharospasm before and 4 weeks after botulinum toxin treatment. Subjects with blepharospasm had significantly lower (= worse) scores for odor threshold and for the composite olfactory score than healthy controls, while odor discrimination, odor identification, and the composite taste score were not different between groups. The adjacent study revealed that botulinum toxin did not impact the chemical senses. In this study, subjects with blepharospasm had a lower (= worse) odor threshold than healthy controls. As olfaction is important in daily life, findings justify further research of olfaction in blepharospasm.

Olfactory Performance in Youth With Full and Subthreshold Avoidant/Restrictive Food Intake Disorder

Background: Avoidant/restrictive (A/R) food intake disorder (ARFID) is characterized by restrictive eating defined by lack of interest in food, sensory sensitivity, and/or fear of aversive consequences of eating resulting in a failure to meet adequate nutritional and/or energy needs. The complex psychopathology that differentiates ARFID from other eating disorders highlights the need to explore the role of sensory systems in disease etiology. Olfaction has an important role in eating behavior. Specifically, olfactory dysfunction is associated with decreased food intake and appetite. Olfactory performance and associated clinical characteristics have yet to be examined in individuals with ARFID. We hypothesized that higher levels of PYY, which signals satiety, would be associated with poorer olfactory performance; whereas greater food fussiness and A/R eating severity would be associated with stronger olfactory performance. Methods: We evaluated a cross-sectional sample of children and adolescents with full and subthreshold ARFID (n=82, 46.2% female, mean age 15.8±3.8). We measured olfactory performance with the Sniffin’ Sticks test (Burghardt®, Wedel, Germany) which captures odor discrimination, odor identification, and odor threshold. Higher scores on all three indices represent stronger olfactory performance. We also measured fasting serum PYY; severity of A/R eating on the Pica, ARFID and Rumination Disorder Interview (PARDI); and food fussiness as a measure of food-related sensory sensitivity on the Adult Eating Behavior Questionnaire. Statistical analyses included T-test and spearman’s correlations. Results: Greater fasting serum PYY levels were associated with significantly poorer performance on the odor threshold test (r=-0.4, p=0.003). Greater severity of A/R eating (r=-0.3 p=0.008) and food fussiness (r=-0.2, p=0.03) were both associated with significantly poorer performance on the odor discrimination test. Conclusions: As predicted, we found that higher levels of PYY were associated with poorer olfactory performance in youth with full and subthreshold ARFID. However, contrary to hypotheses, we found that greater food fussiness and severity of A/R eating were associated with poorer olfactory performance. Future research should investigate whether high levels of PYY and poor olfactory performance are causes, consequences, or correlates of A/R eating.

Postoperative Olfaction Alteration Following Laparoscopic Bariatric Surgery

Introduction: Bariatric surgery is an effective method of treatment for morbid obesity that is known to change nutritional habits. Proper nutrition has an impact on postoperative recovery and outcomes. Diet preferences depend on flavour and olfaction stimuli. Some studies show long-term changes in the sense of smell after bariatric surgery, but little research has addressed olfactory function shortly after surgery. Observations of olfactory changes that occur immediately after bariatric surgery may lead to improvements in postoperative care. Aim: The aim of this study is to investigate the impact of bariatric surgery on olfactory changes in the short postoperative period. Material and methods: This is a prospective study of patients undergoing laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) between April 2018 and December 2018. The control group consists of patients who underwent various non-oncological elective surgical procedures. Patients’ olfaction was tested qualitatively and quantitatively the day before and 24 h after surgery. Sniffin Sticks test consists of three subtests: odor threshold, discrimination, and identification. Results: The study enrolled 83 patients (LSG = 39; LRYGB = 14; control = 30). Mean scores in the threshold subtest differed significantly in the bariatric group, 9.3 ± 3.9 before the surgery and 8.2 ± 3.0 a day after the surgery (p = 0.032). There were no significant differences between scores from the discrimination subtest, identification subtest and the mean total scores in the bariatric group. There was no observed change in the intensity of the smell in the control group. Analyzing the results of patients undergoing LSG and LRYGB separately, we only showed significant differences in the case of LSG. Mean score from the 1st test (9.12 ± 3.97 vs. 7.75 ± 2.98; p = 0.0339) and mean total score (32.83 ± 5.45 vs. 30.67 ± 4.88; p = 0.0173) differ between repetitive measurements in LSG patients. Conclusions: Our study shows deterioration of odor threshold in the bariatric surgery group compared to the control group 24 h after surgery. However, this change occurred only in patients undergoing LSG.

Chemosensory dysfunction in Cushing’s syndrome

Purpose Cushing’s syndrome (CS) can lead to structural changes in the brain and cognitive impairment, but chemosensory function has not been investigated yet. The aim was to analyze sense of smell and taste in patients with CS and explore the effect of therapy. Methods The study cohort comprised 20 patients with florid CS treated between 2018 and 2020 in the outpatient clinic of the LMU Munich. We compared these 20 patients with CS to 40 healthy subjects matched for age, sex, and smoking status. Patients’ sense of smell and taste was examined at diagnosis and 3 months after successful therapeutic surgery leading to clinical and biochemical remission. Odor threshold, discrimination, and identification were measured with “Sniffin’ Sticks”, taste was measured with “Taste Strips”. Perceived sense of smell and taste was retrieved via a questionnaire. Results Patients with florid CS had significantly reduced smell (total smell score 30.3 vs. 34.4, p < 0.0005) and taste scores (9.5 vs. 12.0, p < 0.0005) compared to controls and significantly more frequently hyposmia (55 vs. 2.5%, p < 0.0005), hypogeusia (40 vs. 0%, p < 0.0005), and self-reported chemosensory impairment (60 vs. 0%, p < 0.0005). Three months after successful surgery, CS patients showed significant improvement of odor threshold (8.1 vs. 7.0, p < 0.0005), odor discrimination (12.0 vs. 11.0, p = 0.003), total smell score (33.4 vs. 30.3, p < 0.0005), and taste (11.5 vs. 9.5, p = 0.003). Conclusions Chemosensory dysfunction is a novel and clinically relevant feature of CS.