Computing the Effects of SARS-CoV-2 on Respiration Regulatory Mechanisms in COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been established as a cause of severe alveolar damage and pneumonia in patients with advanced Coronavirus disease (COVID-19). The consolidation of lung parenchyma precipitates the alterations in blood gases in COVID-19 patients that are known to complicate and cause hypoxemic respiratory failure. With SARS-CoV-2 damaging multiple organs in COVID-19, including the central nervous system that regulates the breathing process, it is a daunting task to compute the extent to which the failure of the central regulation of the breathing process contributes to the mortality of COVID-19 affected patients. Emerging data on COVID-19 cases from hospitals and autopsies in the last few months have helped in the understanding of the pathogenesis of respiratory failures in COVID-19. Recent reports have provided overwhelming evidence of the occurrence of acute respiratory failures in COVID-19 due to neurotropism of the brainstem by SARS-CoV-2. In this review, a cascade of events that may follow the alterations in blood gases and possible neurological damage to the respiratory regulation centers in the central nervous system (CNS) in COVID-19 are related to the basic mechanism of respiratory regulation in order to understand the acute respiratory failure reported in this disease. Though a complex metabolic and respiratory dysregulation also occurs with infections caused by SARS-CoV-1 and MERS that are known to contribute toward deaths of the patients in the past, we highlight here the role of systemic dysregulation and the CNS respiratory regulation mechanisms in the causation of mortalities seen in COVID-19. The invasion of the CNS by SARS-CoV-2, as shown recently in areas like the brainstem that control the normal breathing process with nuclei like the pre-Bötzinger complex (pre-BÖTC), may explain why some of the patients with COVID-19, who have been reported to have recovered from pneumonia, could not be weaned from invasive mechanical ventilation and the occurrences of acute respiratory arrests seen in COVID-19. This debate is important for many reasons, one of which is the fact that permanent damage to the medullary respiratory centers by SARS-CoV-2 would not benefit from mechanical ventilators, as is possibly occurring during the management of COVID-19 patients.

Do olfactory and gustatory psychophysical scores have prognostic value in COVID-19 patients? A prospective study of 106 patients

Background

The lack of objective data makes it difficult to establish the prognostic value of chemosensitive disorders in coronavirus disease 2019 (COVID-19) patients. We aimed to prospectively monitor patients diagnosed with COVID-19 to see if the severity of olfactory and gustatory dysfunction associates with subsequent disease severity.

Methods

Multicentre prospective study that recruited 106 COVID-19 subjects at diagnosis. Chemosensitive functions were assessed with psychophysical tests within 4 days of clinical onset, at 10 and 20 days. Daily body temperature and oxygen saturation were recorded as markers of disease severity alongside need for hospitalisation. The correlation between olfactory and gustatory scores and disease severity was assessed with linear regression analysis.

Results

At T0, 71 patients (67%) presented with olfactory dysfunction while gustatory impairment was detected in 76 cases (65.6%). Chemosensitive disorders gradually improved over the observation period. No significant correlations were found between T0 chemosensitive scores and final disease severity. The correlation between olfactory scores and fever proved significant at T2 (p = 0.05), while the relationship with gustatory scores was significant at T1 (p = 0.01) and T2 (p <  0.001), however neither was clinically relevant. The correlation between chemosensitive scores and oxygen saturation was significant only for taste at T2 (p <  0.001). Logistic regression analysis found significant correlations between olfactory impairment severity and need for hospitalization at T2 (OR 3.750, p = 0.005).

Conclusions

Initial objective olfactory and gustatory scores do not seem to have a significant prognostic value in predicting the severity of the COVID-19 course; however, persistence of olfactory dysfunction at 20 days, associated with a more severe course. Unfortunately, olfactory and gustatory dysfunction do not seem to hold prognostic value at the time of initial diagnosis.

Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study

OBJECTIVE

To investigate the occurrence of olfactory and gustatory dysfunctions in patients with laboratory-confirmed COVID-19 infection.

METHODS

Patients with laboratory-confirmed COVID-19 infection were recruited from 12 European hospitals. The following epidemiological and clinical outcomes have been studied: age, sex, ethnicity, comorbidities, and general and otolaryngological symptoms. Patients completed olfactory and gustatory questionnaires based on the smell and taste component of the National Health and Nutrition Examination Survey, and the short version of the Questionnaire of Olfactory Disorders-Negative Statements (sQOD-NS).

RESULTS

A total of 417 mild-to-moderate COVID-19 patients completed the study (263 females). The most prevalent general symptoms consisted of cough, myalgia, and loss of appetite. Face pain and nasal obstruction were the most disease-related otolaryngological symptoms. 85.6% and 88.0% of patients reported olfactory and gustatory dysfunctions, respectively. There was a significant association between both disorders (p < 0.001). Olfactory dysfunction (OD) appeared before the other symptoms in 11.8% of cases. The sQO-NS scores were significantly lower in patients with anosmia compared with normosmic or hyposmic individuals (p = 0.001). Among the 18.2% of patients without nasal obstruction or rhinorrhea, 79.7% were hyposmic or anosmic. The early olfactory recovery rate was 44.0%. Females were significantly more affected by olfactory and gustatory dysfunctions than males (p = 0.001).

CONCLUSION

Olfactory and gustatory disorders are prevalent symptoms in European COVID-19 patients, who may not have nasal symptoms. The sudden anosmia or ageusia need to be recognized by the international scientific community as important symptoms of the COVID-19 infection.

Magnetic resonance imaging of COVID-19 anosmic patients reveals abnormalities of the olfactory bulb: Preliminary prospective study

•

COVID-19 patients with total loss of smell have more olfactory bulb abnormalities at the magnetic resonance imaging than patients without loss of smell.

•

The olfactory bulb MRI abnormalities may be objectified through a signal intensity ratio measurement that is calculated between the average signals of the olfactory bulb and the frontal white matter.

•

The loss of smell is probably due to olfactory bulb inflammation related to virus spread.

Cell type-specific patterned neural activity instructs neural map formation in the mouse olfactory system

The development of precise neural circuits is initially directed by genetic programming and subsequently refined by neural activity. In the mouse olfactory system, axons from various olfactory sensory neurons expressing the same olfactory receptor converge onto a few spatially invariant glomeruli, generating the olfactory glomerular map in the olfactory bulbs. Using the glomerular map formation as a model, this review summarizes the current understanding of mechanisms underlying topographic map development in the mouse olfactory system and highlights how neural activity instructs the map refinement process.

Coincidence of COVID-19 epidemic and olfactory dysfunction outbreak in Iran

Background: The occurrence of anosmia/hyposmia during novel Coronavirus disease 2019 (COVID-19) may indicate a relationship between coincidence of olfactory dysfunction and coronavirus disease 2019 (COVID-19). This study aimed to assess the frequency of self-reported anosmia/hyposmia during COVID-19 epidemic in Iran. Methods: This population-based cross sectional study was performed through an online questionnaire from March 12 to 17, 2020. Cases from all provinces of Iran voluntarily participated in this study. Patients completed a 33-item patient-reported online questionnaire, including smell and taste dysfunction and their comorbidities, along with their basic characteristics and past medical histories. The inclusion criteria were self-reported anosmia/hyposmia during the past 4 weeks, from the start of COVID-19 epidemic in Iran. Results: A total of 10 069 participants aged 32.5±8.6 (7-78) years took part in this study, of them 71.13% women and 81.68% nonsmokers completed the online questionnaire. The correlation between the number of olfactory disorders and reported COVID-19 patients in all provinces up to March 17, 2020 was highly significant (Spearman correlation coefficient = 0.87, P< 0.001). A sudden onset of olfactory dysfunction was reported in 76.24% of the participations and persistent anosmia in 60.90% from the start of COVID19 epidemic. In addition, 80.38% of participants reported concomitant olfactory and gustatory dysfunctions. Conclusion: An outbreak of olfactory dysfunction occurred in Iran during the COVID-19 epidemic. The exact mechanisms by which anosmia/hyposmia occurred in patients with COVID-19 call for further investigations.

Corona Viruses and the Chemical Senses: Past, Present, and Future

A wealth of rapidly evolving reports suggests that olfaction and taste disturbances may be manifestations of the novel COVID-19 pandemic. While otolaryngological societies worldwide have started to consider chemosensory evaluation as a screening tool for COVID-19 infection, the true nature of the relationship between the changes in chemosensory ability and COVID-19 is unclear. Our goal with this review is to provide a brief overview of published and archived literature, as well as the anecdotal reports and social trends related to this topic up to April 29, 2020. We also aim to draw parallels between the clinical/chemosensory symptomology reported in association to past coronavirus pandemics (such as SARS and MERS) and the novel COVID-19. This review also highlights current evidence on persistent chemosensory disturbances after the infection has resolved. Overall, our analysis pinpoints the need for further studies: 1) to better quantify olfaction and taste disturbances associated with SARS-CoV-2 infection, compared to those of other viral and respiratory infections, 2) to understand the relation between smell, taste, and chemesthesis disturbances in COVID-19, and 3) to understand how persistent are these disturbances after the infection has resolved.

Short term depression, presynaptic inhibition and local neuron diversity play key functional roles in the insect antennal lobe

As the oldest, but least understood sensory system in evolution, the olfactory system represents one of the most challenging research targets in sensory neurobiology. Although a large number of computational models of the olfactory system have been proposed, they do not account for the diversity in physiology, connectivity of local neurons, and several recent discoveries in the insect antennal lobe, a major olfactory organ in insects. Recent studies revealed that the response of some projection neurons were reduced by application of a GABA antagonist, and that insects are sensitive to odor pulse frequency. To account for these observations, we propose a spiking neural circuit model of the insect antennal lobe. Based on recent anatomical and physiological studies, we included three sub-types of local neurons as well as synaptic short-term depression (STD) in the model and showed that the interaction between STD and local neurons resulted in frequency-sensitive responses. We further discovered that the unexpected response of the projection neurons to the GABA antagonist is the result of complex interactions between STD and presynaptic inhibition, which is required for enhancing sensitivity to odor stimuli. Finally, we found that odor discrimination is improved if the innervation of the local neurons in the glomeruli follows a specific pattern. Our findings suggest that STD, presynaptic inhibition and diverse physiology and connectivity of local neurons are not independent properties, but they interact to play key roles in the function of antennal lobes.

Electrical stimulation of cranial nerves in cognition and disease

The cranial nerves are the pathways through which environmental information (sensation) is directly communicated to the brain, leading to perception, and giving rise to higher cognition. Because cranial nerves determine and modulate brain function, invasive and non-invasive cranial nerve electrical stimulation methods have applications in the clinical, behavioral, and cognitive domains. Among other neuromodulation approaches such as peripheral, transcranial and deep brain stimulation, cranial nerve stimulation is unique in allowing axon pathway-specific engagement of brain circuits, including thalamo-cortical networks. In this review we amalgamate relevant knowledge of 1) cranial nerve anatomy and biophysics; 2) evidence of the modulatory effects of cranial nerves on cognition; 3) clinical and behavioral outcomes of cranial nerve stimulation; and 4) biomarkers of nerve target engagement including physiology, electroencephalography, neuroimaging, and behavioral metrics. Existing non-invasive stimulation methods cannot feasibly activate the axons of only individual cranial nerves. Even with invasive stimulation methods, selective targeting of one nerve fiber type requires nuance since each nerve is composed of functionally distinct axon-types that differentially branch and can anastomose onto other nerves. None-the-less, precisely controlling stimulation parameters can aid in affecting distinct sets of axons, thus supporting specific actions on cognition and behavior. To this end, a rubric for reproducible dose-response stimulation parameters is defined here. Given that afferent cranial nerve axons project directly to the brain, targeting structures (e.g. thalamus, cortex) that are critical nodes in higher order brain networks, potent effects on cognition are plausible. We propose an intervention design framework based on driving cranial nerve pathways in targeted brain circuits, which are in turn linked to specific higher cognitive processes. State-of-the-art current flow models that are used to explain and design cranial-nerve-activating stimulation technology require multi-scale detail that includes: gross anatomy; skull foramina and superficial tissue layers; and precise nerve morphology. Detailed simulations also predict that some non-invasive electrical or magnetic stimulation approaches that do not intend to modulate cranial nerves per se, such as transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS), may also modulate activity of specific cranial nerves. Much prior cranial nerve stimulation work was conceptually limited to the production of sensory perception, with individual titration of intensity based on the level of perception and tolerability. However, disregarding sensory emulation allows consideration of temporal stimulation patterns (axon recruitment) that modulate the tone of cortical networks independent of sensory cortices, without necessarily titrating perception. For example, leveraging the role of the thalamus as a gatekeeper for information to the cerebral cortex, preventing or enhancing the passage of specific information depending on the behavioral state. We show that properly parameterized computational models at multiple scales are needed to rationally optimize neuromodulation that target sets of cranial nerves, determining which and how specific brain circuitries are modulated, which can in turn influence cognition in a designed manner.

Smad4-dependent morphogenic signals control the maturation and axonal targeting of basal vomeronasal sensory neurons to the accessory olfactory bulb

The vomeronasal organ (VNO) contains two main types of vomeronasal sensory neurons (VSNs) that express distinct vomeronasal receptor (VR) genes and localize to specific regions of the neuroepithelium. Morphogenic signals are crucial in defining neuronal identity and network formation; however, if and what signals control maturation and homeostasis of VSNs is largely unexplored. Here, we found transforming growth factor β (TGFβ) and bone morphogenetic protein (BMP) signal transduction in postnatal mice, with BMP signaling being restricted to basal VSNs and at the marginal zones of the VNO: the site of neurogenesis. Using different Smad4 conditional knockout mouse models, we disrupted canonical TGFβ/BMP signaling in either maturing basal VSNs (bVSNs) or all mature VSNs. Smad4 loss of function in immature bVSNs compromises dendritic knob formation, pheromone induced activation, correct glomeruli formation in the accessory olfactory bulb (AOB) and survival. However, Smad4 loss of function in all mature VSNs only compromises correct glomeruli formation in the posterior AOB. Our results indicate that Smad4-mediated signaling drives the functional maturation and connectivity of basal VSNs.

Summary: Genetic disruption of TGFβ/BMP signaling in maturing basal vomeronasal sensory neurons (VSNs) or in all mature VSNs indicates that Smad4 signaling drives maturation and connectivity of basal VSNs.

How Dietary Deficiency Studies Have Illuminated the Many Roles of Vitamin A During Development and Postnatal Life

Vitamin A deficiency studies have been carried out since the early 1900s. Initially, these studies led to the identification of fat soluble A as a unique and essential component of the diet of rodents, birds, and humans. Continuing work established that vitamin A deficiency produces biochemical and physiological dysfunction in almost every vertebrate organ system from conception to death. This chapter begins with a review of representative historical and current studies that used the nutritional vitamin A deficiency research model to gain an understanding of the many roles vitamin A plays in prenatal and postnatal development and well-being. This is followed by a discussion of recent studies that show specific effects of vitamin A deficiency on prenatal development and postnatal maintenance of the olfactory epithelium, brain, and heart. Vitamin A deficiency studies have helped define the necessity of vitamin A for the health of all vertebrates, including farm animals, but the breadth of deficient states and their individual effects on health have not been fully determined. Future work is needed to develop tools to assess the complete vitamin A status of an organism and to define the levels of vitamin A that optimally support molecular and systems level processes during all ages and stages of life.

Cyclic regulation of Trpm4 expression in female vomeronasal neurons driven by ovarian sex hormones

The vomeronasal organ (VNO), the sensory organ of the mammalian accessory olfactory system, mediates the activation of sexually dimorphic reproductive behavioral and endocrine responses in males and females. It is unclear how sexually dimorphic and state-dependent responses are generated by vomeronasal sensory neurons (VSNs). Here, we report the expression of the transient receptor potential (TRP) channel Trpm4, a Ca²⁺-activated monovalent cation channel, as a second TRP channel present in mouse VSNs, in addition to the diacylglycerol-sensitive Trpc2 channel. The expression of Trpm4 in the mouse VNO is sexually dimorphic and, in females, is tightly linked to their reproductive cycle. We show that Trpm4 protein expression is upregulated specifically during proestrus and estrus, when female mice are about to ovulate and become sexually active and receptive. The cyclic regulation of Trpm4 expression in female VSNs depends on ovarian sex hormones and is abolished by surgical removal of the ovaries (OVX). Trpm4 upregulation can be restored in OVX mice by systemic treatment with 17ß-estradiol, requires endogenous activity of aromatase enzyme, and is strongly reduced during late pregnancy. This cyclic regulation of Trpm4 offers a neural mechanism by which female mice could regulate the relative strength of sensory signals in their VSNs, depending on hormonal state. Trpm4 is likely to participate in sex-specific, estrous cycle-dependent and sex hormone-regulated functions of the VNO, and may serve as a previously unknown genetic substrate for dissecting mammalian sexually dimorphic cellular and behavioral responses.

fMRI study of olfactory processing in mice under three anesthesia protocols: Insight into the effect of ketamine on olfactory processing

Functional magnetic resonance imaging (fMRI) is a valuable tool for studying neural activations in the central nervous system of animals due to its wide spatial coverage and non-invasive nature. However, the advantages of fMRI have not been fully realized in functional studies in mice, especially in the olfactory system, possibly due to the lack of suitable anesthesia protocols with spontaneous breathing. Since mice are widely used in biomedical research, it is desirable to evaluate different anesthesia protocols for olfactory fMRI studies in mice. Dexmedetomidine (DEX) as a sedative/anesthetic has been introduced to fMRI studies in mice, but it has a limited anesthesia duration. To extend the anesthesia duration, DEX has been combined with a low dose of isoflurane (ISO) or ketamine (KET) in previous functional studies in mice. In this report, olfactory fMRI studies were performed under three anesthesia protocols (DEX alone, DEX/ISO, and DEX/KET) in three different groups of mice. Isoamyl-acetate was used as an odorant, and the odorant-induced neural activations were measured by blood oxygenation-level dependent (BOLD) fMRI. BOLD fMRI responses were observed in the olfactory bulb (OB), anterior olfactory nuclei (AON), and piriform cortex (Pir). Interestingly, BOLD fMRI activations were also observed in the prefrontal cortical region (PFC), which are most likely caused by the draining vein effect. The response in the OB showed no adaptation to either repeated odor stimulations or continuous odor exposure, but the response in the Pir showed adaptation during the continuous odor exposure. The data also shows that ISO suppresses the olfactory response in the OB and AON, while KET enhances the olfactory response in the Pir. Thus, DEX/KET should be an attractive anesthesia for olfactory fMRI in mice.

Factors associated with odour identification in older Indonesian and white Australian adults

BACKGROUND AND AIMS

Among older adults, olfactory dysfunction is associated with cognitive impairment, lower quality of life, and increased mortality. While age is a risk factor for olfactory dysfunction, other risk factors are less well understood, and may vary between ethno-regional groups. This study investigated how associations between odour identification (OI) and various risk factors, as well as cognition and language ability, differed or were similar in two distinct ethno-regional groups of older adults.

METHODS

This cross-sectional study used data from two cohorts: 470 Indonesians (aged 67.4 ± 7.4 years) and 819 white Australians (aged 78.7 ± 4.8 years). Univariate and multivariate analyses explored whether OI test scores were associated with age, sex, education, cholesterol levels, apolipoprotein E ε4 status, smoking, diabetes, hypertension and depression scale scores, or with Mini-Mental State Examination (MMSE) and language test performance.

RESULTS

Univariate analyses identified some factors associated with OI scores in both Indonesians and white Australians, including older age and smoking with lower scores, and MMSE and language test performance with higher scores. Multivariate analyses yielded different and mutually exclusive patterns of associations in the two ethno-regional groups, with language test scores significantly associated with higher OI scores in Indonesians, and age, being male, smoking, having diabetes and higher depression scale scores significantly associated with lower OI scores in white Australians.

CONCLUSION

Ethno-regional differences may need consideration in the attempt to fully understand associations between OI and negative outcomes like dementia and mortality, and interventions for olfactory dysfunction might need to be tailored to specific ethno-regional groups. However, the difference in mean age between cohorts is a limitation of this study, and future studies should aim to compare populations with similar age distributions.

Meta-analysis of olfactory dysfunction in 22q11.2 deletion syndrome

A quantitative review of literature concerning olfactory function in 22q11.2 deletion syndrome (22q11DS) patients was performed detailing the scope/magnitude of deficits and probing possible moderators. We searched MEDLINE, EMBASE and PubMed to identify studies for inclusion. Effect sizes were based on differences in psychophysical olfactory tests between 22q11DS patients (n = 194) and typically developing comparison subjects (n = 466). 22q11DS patients exhibited marked olfactory dysfunction (d=-1.11, 95% CI=-1.29<δ<-0.92) that was homogeneous (p = 0.86). Diffuse olfactory deficits were seen which were not moderated by age or sex. 22q11DS patients exhibit large/diffuse deficits in olfactory function that are of a similar magnitude to observed neuropsychological impairments.

Molecular evidence for adaptive evolution of olfactory-related genes in cervids

BACKGROUND

Cervids have evolved very successful means for survival and thriving to adapt to various climates and environments. One of these successful means might be the effective and efficient way of communication. To support this notion, cervids are well equipped with a variety of skin glands that distribute in different body regions. However, studies relevant to adaptive evolution in cervids, particularly on olfactory reception at the molecular level, have thus far not been reported.

OBJECTIVE

To provide valuable insights into molecular evidence for the adaptive evolution of olfactory-related gene in cervids.

METHODS

Based on recently sequenced genomes of cervids and closely-related-species, we performed comparative genomic analysis at genome level using bioinformatics tools.

RESULTS

Tree topology strongly supported that Bovidae was the sister group of Moschidae and both formed a branch that was then clustered with Cervidae. Expansion of heavy chain genes of the dynein family and 51 rapidly evolving genes could be associated with adaptation of cilia that serve as sensory organelles and act as cellular antennae. Based on the branch-site model test along the deer branch spanning 7-21 mammalian species, 14 deer olfactory receptor genes were found to be undergoing positive selection pressure and 89 positive selection sites (probability > 60%) had amino acid substitutions unique to deer.

CONCLUSION

This study, for the first time, provides significant molecular evidence for adaption of olfactory-related genes of cervids according to their olfactory behavior.

Coincidence of COVID-19 epidemic and olfactory dysfunction outbreak in Iran

Background: The occurrence of anosmia/hyposmia during novel Coronavirus disease 2019 (COVID-19) may indicate a relationship between coincidence of olfactory dysfunction and coronavirus disease 2019 (COVID-19). This study aimed to assess the frequency of self-reported anosmia/hyposmia during COVID-19 epidemic in Iran. Methods: This population-based cross sectional study was performed through an online questionnaire from March 12 to 17, 2020. Cases from all provinces of Iran voluntarily participated in this study. Patients completed a 33-item patient-reported online questionnaire, including smell and taste dysfunction and their comorbidities, along with their basic characteristics and past medical histories. The inclusion criteria were self-reported anosmia/hyposmia during the past 4 weeks, from the start of COVID-19 epidemic in Iran. Results: A total of 10 069 participants aged 32.5±8.6 (7-78) years took part in this study, of them 71.13% women and 81.68% nonsmokers completed the online questionnaire. The correlation between the number of olfactory disorders and reported COVID-19 patients in all provinces up to March 17, 2020 was highly significant (Spearman correlation coefficient = 0.87, P< 0.001). A sudden onset of olfactory dysfunction was reported in 76.24% of the participations and persistent anosmia in 60.90% from the start of COVID19 epidemic. In addition, 80.38% of participants reported concomitant olfactory and gustatory dysfunctions. Conclusion: An outbreak of olfactory dysfunction occurred in Iran during the COVID-19 epidemic. The exact mechanisms by which anosmia/hyposmia occurred in patients with COVID-19 call for further investigations.

Importance of 2,4,6-Trichloroanisole (TCA) as an odorant in the emissions from anaerobically stabilized dewatered biosolids

Odours from stabilized biosolids after anaerobic digestion of wastewater sludge can cause local community impact. Apart from the well-known odorants such as sulfur compounds, contributions from other volatile organic compounds (VOCs) to nuisance odours is limited. The presence of compounds with low odour detection thresholds (ODTs) at low concentrations, can present challenges for analytical identification. Thirty-six biosolids samples were taken after anaerobic stabilisation and dewatering at a wastewater treatment plant, Sydney, Australia. Biosolid cake samples were stored outside in loosely covered trays under aerobic conditions, however without interactions with soil microorganisms as it would be in reality. All biosolids cake samples were analysed over a period of 35 days. Emissions were collected onto Tenax TA sorbent tubes using a U.S. EPA flux hood method at storage days 1, 3, 7, 10, 14, 21 and 35. Gas chromatography (GC) coupled with mass spectrometer detector (MSD) and an olfactory detection port (ODP) was used to identify a musty/moldy/earthy type odorant in the biosolids emissions as 2,4,6-trichloroanisole (TCA). Measured odour intensities, classified on a scale from 1 to 4, and odour characters were specified by three ODP assessors. TCA was identified in all biosolid cake emissions. The measured odour intensities of the TCA did not significantly alter as the biosolids were aged, however varied between biosolids cakes. Due to its odour intensity, 85% frequency of detection and its low ODT, which is orders of magnitudes lower than sulfur compounds, TCA should be considered as a potential odorant of concern in biosolids emissions.

Signaling across the senses: a captive case study in pair-bonded red-bellied lemurs (Eulemur rubriventer) at the Duke Lemur Center, NC, USA

We provide a preliminary case study in red-bellied lemurs (Eulemur rubriventer) to illustrate a multimodal approach to understanding communication strategies within a species with obligate pair-bonds. From June to August 2012, we observed and analyzed signaling behaviors across three established red-bellied lemur pairs at Duke Lemur Center (Durham, NC, USA). Our aim was to assess how individuals combine signal modalities to communicate with pair-mates, and to determine whether these strategies vary by time of day, sex, or pair. We analyzed rates of occurrence of touch (allogrooming, mutual grooming, physical contact, and huddling), scent (scent marking and allomarking), and sound (close-distance contact calls) using Wilcoxon rank sum and exact binomial tests. Time of day impacted rates of occurrence across signal modalities, with higher rates of combined signaling within each modality occurring earlier in the day (p < 0.03). Across time periods, all pairs used auditory signals most frequently, followed by olfactory signals, and finally tactile and tactile-olfactory signals (p < 0.01, all comparisons). In fact, auditory signals frequently overlapped the olfactory signaling modality, and travel rarely occurred without accompanying vocalizations. However, red-bellied lemurs spent the highest percentage of their observed time in tactile signaling bouts (on average, 19.5% of total observed time across pairs). Males and females participated equally in most signaling behaviors (p > 0.1), with the exception of scent marking, which males used more frequently (p < 0.01). The results of this study will aid in developing methods and hypotheses to determine how wild red-bellied lemurs communicate to form, maintain, and advertise their pair-bonds.

Optogenetic Food Odor Avoidance Assay

Appetite is tightly linked to the sensory experience of feeding, including the smell, taste, and sight of food. Sensory perception can affect the palatability of food, modulating appetite beyond homeostatic requirements. Hypothalamic neurons that govern feeding are responsive to sensory cues associated with food, including food odors. However, the circuit mechanisms by which sensory information is processed and relayed to feeding nodes to affect feeding behavior is not well understood. Recent work has identified a population of excitatory basal forebrain neurons that modulate potent appetite suppression, as well as respond to food-associated and innately aversive odorants. To investigate this circuitry, we stereotaxically targeted virus expressing Cre-dependent channelrhodopsin to the basal forebrain and implanted fiber optic cannulas over the injection site. Mice were allowed to recover and underwent training to form a passive association of chow with a unique monomolecular odorant. After training, mice were fasted overnight, and were then presented with both the food-associated odor as well as a similar, novel odor in zones of an arena with and without photostimulation. To evaluate whether stimulation of this circuitry influenced sensory modulation of feeding behavior, video recording and behavioral tracking analysis were used to compare time spent investigating either odor. Thus, this protocol provides a useful paradigm to assay the contribution of different circuits in appetitive and aversive behaviors.

Characterizing potential repelling volatiles for "push-pull" strategy against stem borer: a case study in Chilo auricilius

Background

Massive techniques have been evaluated for developing different pest control methods to minimize fertilizer and pesticide inputs. As “push-pull” strategy utilizes generally non-toxic chemicals to manipulate behaviors of insects, such strategy is considered to be environmentally friendly. “Push-pull” strategy has been extraordinarily effective in controlling stem borers, and the identification of new “pushing” or “pull” components against stem borers could be significantly helpful.

Results

In this study, the results of field trapping assay and behavioral assay showed the larvae of C.auricilius, one kind of stem borers, could be deterred by rice plant under tilling stage, its main host crop. The profiles of volatiles were compared between rice plants under two different developmental stages, and α-pinene was identified as a key differential component. The repelling activity of α-pinene against C.auricilius was confirmed by Y-tube olfactometer. For illuminating the olfactory recognition mechanism, transcriptome analysis was carried out, and 13 chemosensory proteins (CSPs) were identified in larvae and 19 CSPs were identified in adult of C.auriciliu, which was reported for the first time in this insect. Among these identified CSPs, 4 CSPs were significantly regulated by α-pinene treatment, and CSP8 showed good binding affinity with α-pinene in vitro.

Conclusions

Overall, C.auricilius could be repelled by rice plant at tilling stage, and our results highlighted α-pinene as a key component in inducing repelling activity at this specific stage and confirmed the roles of some candidate chemosensory elements in this chemo-sensing process. The results in this study could provide valuable information for chemosensory mechanism of C.auricilius and for identification of “push” agent against rice stem borers.

Chemosensory decrease in different forms of olfactory dysfunction

The aim of this study is to investigate the effect of olfactory dysfunction (OD) on the two other chemical senses, namely gustation and the intranasal trigeminal system. Taste and trigeminal function were analyzed in a retrospective cross-sectional study of 178 participants with OD (n = 78 posttraumatic, n = 42 idiopathic, n = 27 post-infectious and n = 31 chronic rhinosinusitis (CRS) OD). All patients had been investigated for OD at our smell and taste outpatient clinic. Evaluation of olfaction was performed by means of the Sniffin' Sticks test (odor threshold, odor discrimination and odor identification), whereas gustatory function was assessed with the Taste Strips test and the intranasal trigeminal sensitivity by means of the lateralization task. The degree of olfactory impairment was found to depend on the cause of OD, but not on patients' age. Patients with posttraumatic OD showed lower olfactory function than patients with idiopathic, post-infectious and CRS OD (p = 0.01). Gustatory and trigeminal sensitivity in turn depended on age rather than the cause of olfactory dysfunction. Partial correlations between olfactory, gustatory, and trigeminal scores, with age as covariate, were significant, showing a decrease of taste and trigeminal function proportional to the OD (p < 0.05). The present data suggest that the three chemical senses are closely connected for humans underlining that in case of OD the remaining chemical senses (taste, trigeminal function) tend to decrease rather than compensate as this is seen for sensory loss in other modalities. This finding has direct clinical implications and importance when dealing with smell and taste disorders.

Relationship Between Odor Identification and Visual Distractors in Children with Autism Spectrum Disorders

Understanding the nature of olfactory abnormalities is crucial for optimal interventions in children with autism spectrum disorders (ASD). However, previous studies that have investigated odor identification in children with ASD have produced inconsistent results. The ability to correctly identify an odor relies heavily on visual inputs in the general population. We tested odor identification in eight children with ASD and eight age-matched children with typical development (TD). After confirming that all children were able to identify each odor without visual input, we measured odor identification under the visual-distractor condition. Odor identification was hindered by visual distractors for all children with ASD but was not affected in all children with TD. Our results improve understanding of odor identification in ASD.

Congenital olfactory impairment is linked to cortical changes in prefrontal and limbic brain regions

The human sense of smell is closely associated with morphological differences of the fronto-limbic system, specifically the piriform cortex and medial orbitofrontal cortex (mOFC). Still it is unclear whether cortical volume in the core olfactory areas and connected brain regions are shaped differently in individuals who suffer from lifelong olfactory deprivation relative to healthy normosmic individuals. To address this question, we examined if regional variations in gray matter volume were associated with smell ability in seventeen individuals with isolated congenital olfactory impairment (COI) matched with sixteen normosmic controls. All subjects underwent whole-brain magnetic resonance imaging, and voxel-based morphometry was used to estimate regional variations in grey matter volume. The analyses showed that relative to controls, COI subjects had significantly larger grey matter volumes in left middle frontal gyrus and right superior frontal sulcus (SFS). COI subjects with severe olfactory impairment (anosmia) had reduced grey matter volume in the left mOFC and increased volume in right piriform cortex and SFS. Within the COI group olfactory ability, measured with the "Sniffin' Sticks" test, was positively associated with larger grey matter volume in right posterior cingulate and parahippocampal cortices whereas the opposite relationship was observed in controls. Across COI subjects and controls, better olfactory detection threshold was associated with smaller volume in right piriform cortex, while olfactory identification was negatively associated with right SFS volume. Our findings suggest that lifelong olfactory deprivation trigger changes in the cortical volume of prefrontal and limbic brain regions previously linked to olfactory memory.

The distribution of bleeding sites in idiopathic hidden arterial epistaxis

OBJECTIVE

To determine the frequency distribution of bleeding sites in idiopathic hidden arterial epistaxis.

METHODS

In this retrospective cohort study, 107 patients with hidden arterial epistaxis were endoscopically examined for sites of bleeding.

RESULTS

All sites of hidden arterial epistaxis were identified by endoscopic examination. Bleeding sites were identified at initial surgery in 103 patients and during the second surgery in 4. The bleeding sites included: the olfactory cleft region in 47 patients, the inferior meatus region in 29, the middle meatus region in 11, multiple bleeding sites (olfactory cleft and anterior septum) in 3, the anterior roof of the nasal cavity in 4, the nasal floor in 11 and the nasopharynx in 2. The bleeding points showed a white or red volcano-like bump in 75 patients, isolated prominent telangiectasia in 21 and mucosal ulceration in 11.

CONCLUSION

Common sites of hidden arterial epistaxis include the olfactory cleft, inferior meatus and middle meatus. However, there should be awareness of some uncommon bleeding sites (including the anterior roof of the nasal cavity, the nasal floor and the nasopharynx) and of multiple bleeding sites.