Clinical evaluation of oropharyngeal dysphagia in Machado-Joseph disease

CONTEXT: In Machado-Joseph disease, poor posture, dystonia and peripheral neuropathy are extremely predisposing to oropharyngeal dysphagia, which is more commonly associated with muscular dystrophy. OBJECTIVE: To evaluate the clinical characteristics of oropharyngeal dysphagia in Machado-Joseph disease patients. METHOD: Forty individuals participated in this study, including 20 with no clinical complaints and 20 dysphagic patients with Machado-Joseph disease of clinical type 1, who were all similar in terms of gender distribution, average age, and cognitive function. The medical history of each patient was reviewed and each subject underwent a clinical evaluation of deglutition. At the end, the profile of dysphagia in patients with Machado-Joseph disease was classified according to the Severity Scale of Dysphagia, as described by O'Neil and collaborators. RESULTS: Comparison between dysphagic patients and controls did not reveal many significant differences with respect to the clinical evaluation of the oral phase of deglutition, since afflicted patients only demonstrated deficits related to the protrusion, retraction and tonus of the tongue. However, several significant differences were observed with respect to the pharyngeal phase. Dysphagic patients presented pharyngeal stasis during deglutition of liquids and solids, accompanied by coughing and/or choking as well as penetration and/or aspiration; these signs were absent in the controls. CONCLUSIONS: Oropharyngeal dysphagia is part of the Machado-Joseph disease since the first neurological manifestations. There is greater involvement of the pharyngeal phase, in relation to oral phase of the deglutition. The dysphagia of these patients is classified between mild and moderate

Oxygen regulation of breathing through an olfactory receptor activated by lactate

Animals have evolved homeostatic responses to changes in oxygen availability that act on different timescales. Although the hypoxia-inducible factor (HIF) transcriptional pathway that controls long-term responses to low oxygen (hypoxia) has been established, the pathway that mediates acute responses to hypoxia in mammals is not well understood. Here we show that the olfactory receptor gene Olfr78 is highly and selectively expressed in oxygen-sensitive glomus cells of the carotid body, a chemosensory organ at the carotid artery bifurcation that monitors blood oxygen and stimulates breathing within seconds when oxygen declines. Olfr78 mutants fail to increase ventilation in hypoxia but respond normally to hypercapnia. Glomus cells are present in normal numbers and appear structurally intact, but hypoxia-induced carotid body activity is diminished. Lactate, a metabolite that rapidly accumulates in hypoxia and induces hyperventilation, activates Olfr78 in heterologous expression experiments, induces calcium transients in glomus cells, and stimulates carotid sinus nerve activity through Olfr78. We propose that, in addition to its role in olfaction, Olfr78 acts as a hypoxia sensor in the breathing circuit by sensing lactate produced when oxygen levels decline