Jae-Kap Choi

Effects of mandibular advancement on upper airway dimension and collapsibility in patients with obstructive sleep apnea using dynamic upper airway imaging during sleep

OBJECTIVES The objective of this study was to evaluate the effects of mandibular advancement on oropharyngeal dimension and collapsibility and reveal the predominate site of change produced by mandibular advancement in patients with obstructive sleep apnea (OSA). STUDY DESIGN Sixteen adults (13 males and 3 females) with symptomatic mild to severe OSA participated. Custom-made silicone mandibular positioners were used to keep the mandible at 67% of maximum advancement. Changes in the oropharyngeal size and collapsibility with mandibular advancement were evaluated using ultrafast computed tomography taken during wakefulness and midazolam-induced sleep. Cross-sectional areas were assessed using electron beam tomography at 4 levels: high retropalatal (HRP), low retropalatal (LRP), high retroglossal (HRG), and low retroglossal (LRG). RESULTS During sleep, the minimum cross-sectional areas decreased 36.5%, 67.8%, 75.5%, and 65.8% at each level of HRP, LRP, HRG, and LRG respectively, as compared with those measured during wakefulness. Mandibular advancement during sleep increased 75.7%, 141.3%, 128.1%, and 119.9% at each level. The oropharynx showed 70.3%, 110.4%, 140.3%, and 156.9% increase in the Collapsibility Indices during sleep at each level of HRP, LRP, HRG, and LRG, respectively, compared with wakefulness. However, collapsibility indices decreased 29.1%, 23.2%, 21.4%, and 34.1% at each level with mandibular advancement. CONCLUSION Mandibular advancement increases oropharyngeal diameter and decreases oropharyngeal collapsibility during midazolam-induced sleep respiration at the retropalatal as well as the retroglossal region in most patients with OSA.

Adenosine A1 receptors inhibit GABAergic transmission in rat tuberomammillary nucleus neurons

The adenosinergic modulation of GABAergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs) was investigated in mechanically dissociated rat tuberomammillary nucleus (TMN) neurons using a conventional whole‐cell patch clamp technique. Adenosine (100 μM) reversibly decreased mIPSC frequency without affecting the current amplitude, indicating that adenosine acts presynaptically to decrease the probability of spontaneous GABA release. The adenosine action on GABAergic mIPSC frequency was completely blocked by 1 μM DPCPX, a selective A1 receptor antagonist, and mimicked by 1 μM CPA, a selective A1 receptor agonist. This suggests that presynaptic A1 receptors were responsible for the adenosine‐mediated inhibition of GABAergic mIPSC frequency. CPA still decreased GABAergic mIPSC frequency even either in the presence of 200 μM Cd2+, a general voltage‐dependent Ca2+ channel blocker, or in the Ca2+‐free external solution. However, the inhibitory effect of CPA on GABAergic mIPSC frequency was completely occluded by 1 mM Ba2+, a G‐protein coupled inwardly rectifying K+ (GIRK) channel blocker. In addition, the CPA‐induced decrease in mIPSC frequency was completely occluded by either 100 μM SQ22536, an adenylyl cyclase (AC) inhibitor, or 1 μM KT5720, a specific protein kinase A (PKA) inhibitor. The results suggest that the activation of presynaptic A1 receptors decreases spontaneous GABAergic transmission onto TMN neurons via the modulation of GIRK channels as well as the AC/cAMP/PKA signal transduction pathway. This adenosine A1 receptor‐mediated modulation of GABAergic transmission onto TMN neurons may play an important role in the fine modulation of the excitability of TMN histaminergic neurons as well as the regulation of sleep‐wakefulness.

5‐HT1B receptors inhibit glutamate release from primary afferent terminals in rat medullary dorsal horn neurons

BACKGROUND AND PURPOSE Although 5‐HT1B receptors are expressed in trigeminal sensory neurons, it is still not known whether these receptors can modulate nociceptive transmission from primary afferents onto medullary dorsal horn neurons.

Effect of Jaw and Head Position on Airway Resistance in Obstructive Sleep Apnea

This study evaluated whether changes in jaw and neck position caused substantial airway resistance (Raw) changes in normal controls and obstructive sleep apnea (OSA) subjects. Subject groups included 12 male nocturnal polysomnographically diagnosed OSA patients and 16 healthy male control subjects. Raw was assessed plethysmographically and measured under the following conditions: neutral head posture with 0/3, 1/3, 2/3, or 3/3 of the subjects maximum forward jaw position; normal jaw (0/3 forward) with fully flexed, extended, right or left rotated head position. Both groups showed a similar significant decrease in Raw upon jaw protrusion. OSA patients showed a significantly higher baseline (normal jaw, neutral head posture). Raw and both subject groups also had a clear increase in their airway resistance with flexion and to a lesser extent with neck rotation and extension. These data document that airway resistance can be significantly influenced by head and jaw positioning with protrusion of the jaw reducing Raw and flexing the neck increasing Raw.

The presence of altered craniocervical posture and mobility in smartphone-addicted teenagers with temporomandibular disorders

[Purpose] Smartphones are widely used by teenagers and adults for various purposes. As teenagers use smartphones more actively than adults, they are more prone to be addicted to smartphones. Furthermore, excessive usage of smartphones can lead to various psychosocial and physical symptoms. [Subjects and Methods] One hundred teenage subjects were recruited and divided into normal and addiction groups, based on the criteria of the smartphone addiction scale-short version questionnaire. Craniocervical posture and mobility were examined by lateral cephalometric analysis and a cervical range of motion instrument. [Results] Cephalometric analysis showed no significant difference in the craniocervical angles of the resting positions of the two groups. However, measurement using an inclinometer revealed a significantly flexed cervical posture while using smartphones and decreased cervical range of motion in the smartphone-addicted teenagers. The clinical profile of temporomandibular disorders revealed that muscular problems were more frequently presented in the smartphone-addicted teenagers. [Conclusion] These findings suggest that smartphone addiction has a negative influence on craniocervical posture and mobility. Further, it can be postulated that smartphone addiction among teenagers may have contributed to the occurrence of myogenous temporomandibular disorders. In conclusion, smartphone-addicted teenagers may be more frequently subjected to muscular disturbance in the craniocervical area, which probably affects the pathologic process of temporomandibular disorders in teenagers.

Loss of toll-like receptor 3 aggravates hepatic inflammation but ameliorates steatosis in mice

The importance of toll-like receptor (TLR) 4 in the pathogenesis of steatohepatitis has been well documented; however, little is known about the role of TLR3. In this study, we determined whether the depletion of TLR3 modulated hepatic injury in mice and further aimed to provide mechanistic insights into the TLR3-mediated modulation of diet-induced hepatic inflammation and fat accumulation. Hepatic steatosis and inflammatory response were induced by feeding wild-type (WT) or TLR3 knockout mice a high-fat diet for 8 weeks. Primary liver resident cells, including hepatocytes, Kupffer cells, and hepatic stellate cells (HSCs), were treated with palmitic acid. TLR3 knockout mice fed a high-fat diet showed severe hepatic inflammation accompanied by nuclear factor-κB and IRF3 activation, which is mainly induced by the activation of Kupffer cells. Decreased TLR4 expression was restored in hepatic mononuclear cells and Kupffer cells in TLR3 knockout mice compared to that in the WT. Moreover, hepatic steatosis was decreased in TLR3 knockout mice. Hepatocytes from TLR3 knockout mice exhibited reduced expression of cannabinoid receptors. HSCs from TLR3 knockout mice showed decreased expression of the enzymes involved in endocannabinoid synthesis. In conclusion, this study suggests that the selective modulation of TLR3 could be a novel therapeutic target for the treatment of hepatic inflammation and steatosis.

Clinical Consideration of Trigger Point Injection/Dry Needling Therapy: A Narrative Review

Received September 8, 2017 Revised September 13, 2017 Accepted September 14, 2017 Myogenous temporomandibular disorder is a collective term for pathologic conditions of the masticatory muscles, mainly characterized by pain and dysfunction associated with various pathophysiological processes. Among the subtypes of myogenous temporomandibular disorder, myofascial pain is one of the most common muscle disorders, characterized by the presence of trigger points (TrPs). Various modalities, such as ultrasound, manipulative therapy, sprayand-stretch technique, transcutaneous electrical nerve stimulation, injection/dry needling, and low-level laser therapy are used to inactivate TrPs. Needling/injection on the TrPs is one of the most common treatments for myofascial pain. Despite the evidence, there is continued controversy over defining the biological and clinical characteristics of TrPs and the efficacy of injection/dry needling. This review discusses the current concept of injection/needling to relieve TrPs.

Oral Submucous Fibrosis in a 26-Year-Old Sri Lankan Man Living in South Korea

Received August 22, 2017 Revised September 14, 2017 Accepted September 14, 2017 Oral submucous fibrosis (OSF) is a premalignant condition characterized by juxtaepithelial fibrosis of the oral cavity. The clinical manifestations include burning sensation to spicy food, blanched oral mucosa with palpable fibrous bands, trismus, depapillation of tongue, and dry mouth. As OSF is predominantly seen in people of the Indian subcontinent, cases of this disease have been rarely reported in South Korea. We present a case of OSF in a Sri Lankan man living in South Korea and emphasize the importance of enhancing knowledge of this disease while the number of immigrants is increasing.

Factors Influencing the Xerostomia Symptoms in the Patients with Temporomandibular Disorders

Purpose: This study investigated factors influencing the xerostomia symptoms in the patients with temporomandibular disorders (TMDs). Methods: Eighty-six participants over the age of twenty were randomly enrolled from patients with TMDs. The patients were diagnosed by Diagnostic Criteria-TMD (DC-TMD). Intensity of the pain and level of stress of the patients were recorded using TMD pain visual analogue scale (VAS) and stress VAS, respectively. The Symptom Checklist-90-Revised (SCL-90R), dry mouth symptom questionnaire, unstimulated salivary flow rate (USFR) and oral moisture were measured. Results: The patients who had above the mean of the TMD pain VAS had significantly higher scores on the stress VAS, subjective dry mouth symptoms and T-score of somatization. The patients who suffered from pain more than three months had significantly higher TMD pain VAS, subjective dry mouth symptoms and T-score of somatization. There were no significant differences in xerostomic symptoms according to the diagnosis of TMDs. Moreover, TMD pain VAS and the stress VAS did not correlated to USFR and oral moisture. Conclusions: The level of individuals’ TMD pain and stress significantly affect their subjective dry mouth symptoms, however, it did not affect USFR and oral moisture.

Factors Influencing the Duration of Occlusal Appliance Treatment for Patients with Temporomandibular Joint Internal Derangement

Purpose: The purpose of this study is to determine factors influencing the duration of occlusal appliance (OA) treatment for patients with temporomandibular joint (TMJ) internal derangement. Methods: Ninety patients were included for this study, who satisfied the following including criteria: (ⅰ) those who were diagnosed as disc displacement of TMJ by taking magnetic resonance imaging (MRI) and (ⅱ) those who were finished OA treatment. The subjects were classified into three groups according to the period of OA treatment: (ⅰ) early response group (＜6 months), (ⅱ) moderate response group (6 months-1 year), and (ⅲ) delayed response group (＞1 year). Demographic data, data from chief complaints and past history of temporomandibular disorder, data from clinical examination and diagnostic imaging including panoramic view and TMJ MRI were compared among groups. One-way ANOVA and chi-square analysis were used to test statistical significance. Results: There were no significant differences in demographic data, data from chief complaints and TMJ imaging. However, only the prevalence of oral parafunctional habits including bruxism, clenching, and unilateral chewing showed significant differences among groups. Conclusions: Oral parafunctional habits could be factors to influence the duration of OA treatment in the patients with TMJ internal derangement.