T&amp;T Olfactometer for Standardized Olfactory Test and Its Uses

Saiki, Katsunori; Fukazawa, Osamu; Asaka, Hideyo; Takagi, Sadayuki F.

doi:10.1007/978-4-431-68355-1_140

Cited by 4 publications

(4 citation statements)

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“…The relative magnitude of the hypoxic metabolic response is greater in smaller mammals than in larger mammals, and is also greater in the cold than within the thermoneutral zone in all species studied to date (Saiki et al 1994;Barros et al 2001). The relative magnitude of the hypoxic metabolic response also appears to vary with the degree of heterothermic expression, with adult heterotherms exhibiting a greater reduction in body temperature and O 2 consumption rate in hypoxia than adult homeotherms (Frappell et al 1992; Barros et al 2001).…”

Section: Introductionmentioning

confidence: 93%

Hypoxia alters the thermogenic response to cold in adult homeothermic and heterothermic rodents

Dzal

Milsom

2019

The Journal of Physiology

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Key points For small mammals living in a cold, hypoxic environment, supplying enough O2 to sustain thermogenesis can be challenging. While heterothermic mammals are generally more tolerant of cold and hypoxia than homeothermic mammals, how they regulate O2 supply and demand during progressive cooling in hypoxia is largely unknown. We show that as ambient temperature is reduced in hypoxia, body temperature falls in both homeotherms and heterotherms. In the homeothermic rat, a decrease in O2 consumption rate and lung O2 extraction accompany this fall in body temperature, despite a relative hyperventilation. Paradoxically, in heterothermic mice, hamsters and ground squirrels, body temperature decreases more than in the homeothermic rat, even though they maintain ventilation, increase lung O2 extraction and maintain or elevate their O2 consumption rates. Variation in cold and hypoxia tolerance among homeotherms and heterotherms reflects divergent strategies in how O2 supply and demand are regulated under thermal and hypoxic challenges. Abstract Compared to homeothermic mammals, heterothermic mammals are reported to be exceptionally tolerant of cold and hypoxia. We hypothesised that this variation in tolerance stems from divergent strategies in how homeotherms and heterotherms regulate O2 supply versus O2 demand when exposed to hypoxia during progressive cooling. To test this hypothesis, we exposed adult rodents ranging in their degree of heterothermic expression (homeotherm: rats, facultative heterotherms: mice and hamsters, and obligate heterotherm: ground squirrels) to either normoxia (21% O2) or environmental hypoxia (7% O2), while reducing ambient temperature from 38 to 5°C. We found that when ambient temperature was reduced in normoxia, all species increased their O2 consumption rate and ventilation in parallel, maintaining a constant ventilatory equivalent and level of lung O2 extraction. Surprisingly, body temperature fell in all species, significantly so in the heterotherms. When ambient temperature was reduced in hypoxia, however, the homeothermic rat decreased their O2 consumption rate and lung O2 extraction despite an increase in their ventilatory equivalent, indicative of a relative hyperventilation. Heterotherms (mice, hamsters and ground squirrels), on the other hand, decreased their ventilatory equivalent, but increased lung O2 extraction and maintained or elevated their O2 consumption rates, yet their body temperature fell even more than in the rat. These results are consistent with the idea that homeotherms and heterotherms diverge in the strategies they use to match O2 supply and O2 demand, and that enhanced cold and hypoxia tolerance in heterotherms may stem from an improved ability to extract O2 from the inspired air.

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Section: Introductionmentioning

confidence: 93%

Hypoxia alters the thermogenic response to cold in adult homeothermic and heterothermic rodents

Dzal

Milsom

2019

The Journal of Physiology

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“…Odor threshold is considered a purely olfactory activity indicator, depending on the integrity of the olfactory neuroepithelium and OSN transduction. Changes in the odor threshold are usually detected using a T&T olfactometer and olfactory perception threshold test kits like Olfactolab No.11 (Saiki et al, 1994;Fortier et al, 1991). The test requires repetitive trials with defined intervals between exposures to the odors.…”

Section: Olfactory Biomarkers In Admentioning

confidence: 99%

Olfactory dysfunction in the pathophysiological continuum of dementia

Bathini

Brai

Albèri

2019

Ageing Research Reviews

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A B S T R A C TSensory capacities like smell, taste, hearing, vision decline with aging, but increasing evidence show that sensory dysfunctions are one of the early signs diagnosing the conversion from physiological to pathological brain state. Smell loss represents the best characterized sense in clinical practice and is considered as one of the first preclinical signs of Alzheimer's and Parkinson's disease, occurring a decade or more before the onset of cognitive and motor symptoms. Despite the numerous scientific reports and the adoption in clinical practice, the etiology of sensory damage as prodromal of dementia remains largely unexplored and more studies are needed to resolve the mechanisms underlying sensory network dysfunction. Although both cognitive and sensory domains are progressively affected, loss of sensory experience in early stages plays a major role in reducing the autonomy of demented people in their daily tasks or even possibly contributing to their cognitive decline. Interestingly, the chemosensory circuitry is devoid of a blood brain barrier, representing a vulnerable port of entry for neurotoxic species that can spread to the brain. Furthermore, the exposure of the olfactory system to the external environment make it more susceptible to mechanical injury and trauma, which can cause degenerative neuroinflammation. In this review, we will summarize several findings about chemosensory impairment signing the conversion from healthy to pathological brain aging and we will try to connect those observations to the promising research linking environmental influences to sporadic dementia. The scientific body of knowledge will support the use of chemosensory diagnostics in the presymptomatic stages of AD and other biomarkers with the scope of finding treatment strategies before the onset of the disease. ⁎

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“…Total improvement rate ¼ (cured cases þ significantly improved cases þ improved cases)/total cases. 4…”

Section: Tandt Olfactory Testmentioning

confidence: 99%

Effects of Age on Recovery of Olfactory Function After Endoscopic Sinus Surgery and Related Risk Factors

Feng

et al. 2021

Ear Nose Throat J

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Objectives: To study the effects of age on the olfactory function recovery of chronic rhinosinusitis patients after endoscopic sinus surgery and related risk factors. Methods: A total of 176 chronic rhinosinusitis (CRS) patients enrolled from February 2017 to October 2019 were divided into child, youth, middle-aged, and elderly groups. Their baseline data, T&T olfactory test score, visual analogue scale (VAS) olfactory score, sinus computed tomography (CT) Lund-Mackay score, and Lund-Kennedy score were compared. Based on postoperative olfactory function, they were divided into good and poor improvement groups. Results: Complication with nasal polyps, allergic rhinitis history, and sinus surgery history had significant differences among patients of different ages ( P < .05). Three months after surgery, T&T olfactory, VAS olfactory, Lund-Mackay, and Lund-Kennedy scores all rose with increasing age, with significant differences between any 2 groups ( P < .05). The improvement of postoperative olfactory function became poorer with aging ( P < .05). T&T and VAS olfactory scores had significant positive correlations with Lund-Mackay and Lund-Kennedy scores ( P < .001). Age, preoperative Lund-Mackay and Lund-Kennedy scores, complication with nasal polyps, allergic rhinitis history, sinus surgery history, and postoperative complications were risk factors for the poor improvement of postoperative olfactory function. Doctor-directed treatment was a protective factor for good improvement. Conclusions: The improvement of olfactory function of CRS patients after endoscopic sinus surgery declines with aging. Age, preoperative Lund-Mackay and Lund-Kennedy scores, complication with nasal polyps, allergic rhinitis history, sinus surgery history, and postoperative complications are risk factors for the poor improvement of postoperative olfactory function. Doctor-directed treatment is a protective factor for good improvement.

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T&T Olfactometer for Standardized Olfactory Test and Its Uses

Cited by 4 publications

References 0 publications

Hypoxia alters the thermogenic response to cold in adult homeothermic and heterothermic rodents

Hypoxia alters the thermogenic response to cold in adult homeothermic and heterothermic rodents

Olfactory dysfunction in the pathophysiological continuum of dementia

Effects of Age on Recovery of Olfactory Function After Endoscopic Sinus Surgery and Related Risk Factors

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