• Toxicological Research
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• v.33 no.4
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• pp.333-342
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• 2017

Ethyl formate, a volatile solvent, has insecticidal and fungicidal properties and is suggested as a potential fumigant for stored crop and fruit. Its primary contact route is through the respiratory tract; however, reliable repeated toxicological studies focusing on the inhalation route have not been published to date. Therefore, the present study was conducted to investigate the safety of a 90-day repeated inhalation exposure in rats. Forty male and 40 female rats were exposed to ethyl formate vapor via inhalation at concentrations of 0, 66, 330, and 1,320 ppm for 6 hr/day, 5 days a week for 13 weeks. Clinical signs, body weights, food consumption, urinalysis, hematologic parameters, serum chemistry measurements, organ weights, necropsy, and histopathological findings were compared between the control and ethyl formate-exposed groups. Locomotor activity decreased during exposure and recovered afterward in male and female rats exposed to 1,320 ppm ethyl formate. Body weight and food consumption continuously decreased in both sexes exposed to 1,320 ppm ethyl formate from week 1 or 3 compared with the control values. The increases in adrenal weight and decreases in thymus weight were noted in both sexes exposed to ethyl formate at 1,320 ppm. Degeneration, squamous metaplasia of olfactory epithelium in the nasopharyngeal tissue, or both were noted in the male and female rats at 1,320 ppm and female rats at 330 ppm ethyl formate. Taken together, our results indicate that ethyl formate-induced changes were not observed in male and female rats at 330 and 66 ppm, respectively. This indicates that exposure to ethyl formate at concentrations below 66 ppm for 90 days is relatively safe in rats. This is the first report of a full-scale repeated inhalation toxicity assessment in rats and could contribute to controlling occupational environmental hazards related to ethyl formate.

• Journal of Yeungnam Medical Science
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• v.35 no.1
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• pp.70-75
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• 2018

Background: Otitis media with effusion (OME) is defined as middle ear effusion without acute signs of infection. OME usually resolves spontaneously; however, persistent OME may require the insertion of a ventilation tube. This study investigated risk factors for persistent OME in children who undergo ventilation tube insertion. Methods: Children who were admitted to undergo ventilation tube insertion at Jeju National University Hospital between August 2015 and July 2016 were enrolled as the case group. Healthy children without persistent OME from August 2016 to July 2017 were enrolled as the control group. Baseline characteristics and predisposing factor data were collected using an interview questionnaire. Middle ear fluids were collected from the case group. Results: A total of 31 patients underwent ventilation tube insertion. The mean age of the case group was 4.53 years, with a male-to-female ratio of 21:10. Twenty-nine (93.5%) children attended a daycare center, and 21 (67.7%) had experience with bottle feeding. Fifteen (48.4%) children in the case group and 3 (9.7%) in the control group first attended a daycare center at <1 year of age (odds ratio=9.96; 95% confidence interval=2.44-39.70; p=0.001). No bacteria were found in middle ear fluid collected from the 31 operated children. Nasopharyngeal bacterial colonization was found in 13 (41.9%) and 17 (54.8%) children in the case and control groups, respectively. Conclusion: Earlier attendance at a daycare center was the only predisposing factor for ventilation tube insertion in our study. The aseptic nature of middle ear fluids found in children with OME highlights the efficacy of antimicrobial use.

• Korean Journal of Bronchoesophagology
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• v.4 no.1
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• pp.52-58
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• 1998

BACKGROUND： Aspiration is defined as the laryngeal penetration of secretions below the level of the true vocal cords. Aspiration can result in life-threatening complications, such as bronchospasm, airway obstruction, pneumonia, pulmonary abscess, sepsis, and death. The patient with high vagal palsy had significant aspiration and dysphagia OBJECTIVE： To formulate a step-by-step management paradign for the patients with high vagal palsy MATERIALS AND METHODS : The medical records of 23 patients who were diagnosed as high vagal palsy from September, 1995 to April, 1998 in Seoul National University Hospital were reviewed retrospectively. Eleven patients were managed conservatively and 12 patients were operated to treat chronic aspiration. RESULTS : The main etiologies of high vagal palsy were mass lesions of the skull base such as neurogenic tumor, pseudotumor, meningioma or nasopharyngeal carcinoma. Aspiration and dysphagia improved in 7 out of 11 patients who were managed conservatively after 2.2 months on the average. The patients who were refractory to the conservative management underwent surgery and showed improvement in 10 out of 12 patients. The employed surgical modalities were vocal cord medialization combined with cricopharyngeal myotomy in 7 patients, laryngotracheal separation in 3 patients and arytenoid adduction only in 2 patients. Two patients still had gastrostomy tube due to the persistent symptoms. Two patients had improved after surgery, but died of underlying disease. CONCLUSION : The patients with high vagal palsy are recommended to be managed conservatively for the first 2 months. If aspiration and dysphagia are persisting after conservative management, vocal cord medialization combined with or without cricopharyngeal myotomy should be considered. If failed, laryngotracheal separation or gastrostomy will be the next option based on the control of the oropharyngeal secretion.

• Clinical and Experimental Pediatrics
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• v.64 no.5
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• pp.239-246
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• 2021

Background: The consequences of severe acute respiratory syndrome corona virus 2 on mother and fetus remain unknown due to a lack of robust evidence from prospective studies. Purpose: This study evaluated the effect of coronavirus disease 2019 (COVID-19) on neonatal outcomes and the scope of vertical transmission. Methods: This ambispective observational study enrolled pregnant women with COVID-19 in North India from April 1 to August 31, 2020 to evaluate neonatal outcomes and the risk of vertical transmission. Results: A total of 44 neonates born to 41 COVID-19-positive mothers were evaluated. Among them, 28 patients (68.3%) (2 sets of twins) were delivered within 7 days of testing positive for COVID-19, 23 patients (56%) (2 sets of twins) were delivered by cesarean section; 13 newborns (29.5%) had low birth weight; 7 (15.9%) were preterm; and 6 (13.6%) required neonatal intensive care unit admission, reflecting an increased incidence of cesarean delivery and low birth weight but zero neonatal mortality. Samples of cord blood, placental membrane, vaginal fluid, amniotic fluid, peritoneal fluid (in case of cesarean section), and breast milk for COVID-19 reverse transcription-polymerase chain reaction tested negative in 22 prospective delivery cases. Nasopharyngeal swabs of 2 newborns tested positive for COVID-19: one at 24 hours and the other on day 4 of life. In the former case, biological samples were not collected as the mother was asymptomatic and her COVID-19 report was available postdelivery; hence, the source of infection remained inconclusive. In the latter case, all samples tested negative, ruling out the possibility of vertical transmission. All neonates remained asymptomatic on follow-up. Conclusion: COVID-19 does not have direct adverse effects on the fetus per se. The possibility of vertical transmission is almost negligible, although results from larger trials are required to confirm our findings.

• The korean journal of orthodontics
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• v.52 no.5
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• pp.345-353
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• 2022

Objective: To investigate airway volumes using cone-beam computed tomography (CBCT) by skeletal patterns, sex, and cervical vertebral maturation (CVM) stages in Korean adolescents. Methods: The sample consisted of pretreatment CBCT and cephalograms of 95 adolescents (aged 12-19) obtained out of 1,611 patients examined for orthodontic treatment from 2018 to 2020 in Kyungpook National University Dental Hospital. The samples were classified into two sex groups; three skeletal pattern groups, four chronological age groups and four CVM stages. Nasopharyngeal volumes (NPV), oropharyngeal volumes (OPV), total pharyngeal airway volume (TAV) and minimum cross-sectional area (MCA) measurements were taken from the CBCT. Multiple linear regression analyses to find out which one of the independent variables are good predictors for airway variables. Significant factors were analyzed by two-way multivariate analysis of variance (MANOVA) then multiple comparisons were analyzed using a t-test, and Fisher least significant difference. Results: Age, sex, CVM, and Sella-Nasion-B point have significant influence on airway variable. Males and females showed similar patterns of change in chronological age groups 1-3; however, males had larger NPV, OPV, and MCA at CVM in group 4. According to CVM stages, males had larger OPV, TAV, and MCA at CVM stage 6 (p-value: 0.019, 0.021, 0.015, respectively) and no sex differences at CVM stages 3, 4, and 5. Conclusions: Skeletal patterns have an effect on airway volume. Sex differences were found in CVM 6.

• Clinical and Experimental Pediatrics
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• v.64 no.12
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• pp.652-660
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• 2021

Background: Viral load and shedding duration are highly associated with the transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. However, limited studies have reported on viral load or shedding in children and adolescents infected with sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Purpose: This study aimed to investigate the natural course of viral load in asymptomatic or mild pediatric cases. Methods: Thirty-one children (<18 years) with confirmed SARS-CoV-2 infection were hospitalized and enrolled in this study. Viral loads were evaluated in nasopharyngeal swab samples using real-time reverse transcription polymerase chain reaction (E, RdRp, N genes). cycle threshold (Ct) values were measured when patients met the clinical criteria to be released from quarantine. Results: The mean age of the patients was 9.8 years, 18 (58%) had mild disease, and 13 (42%) were asymptomatic. Most children were infected by adult family members, most commonly by their mothers. The most common symptoms were fever and sputum (26%), followed by cough and runny nose. Nine patients (29%) had a high or intermediate viral load (Ct value≤30) when they had no clinical symptoms. Viral load showed no difference between symptomatic and asymptomatic patients. Viral rebounds were found in 15 cases (48%), which contributed to prolonged viral detection. The mean duration of viral detection was 25.6 days. Viral loads were significantly lower in patients with viral rebounds than in those with no rebound (E, P=0.003; RdRp, P=0.01; N, P=0.02). Conclusion: Our study showed that many pediatric patients with coronavirus disease 2019 (COVID-19) experienced viral rebound and showed viral detection for more than 3 weeks. Further studies are needed to investigate the relationship between viral rebound and infectiousness in COVID-19.

• Pediatric Infection and Vaccine
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• v.30 no.2
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• pp.91-96
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• 2023

Infection with enterovirus (EV) 71 is usually associated with hand-foot-and-mouth disease and herpangina. The most frequent neurologic complication is brainstem encephalitis. A 30-month-old boy visited the pediatric emergency department with fever, lethargy, and abnormal eye contact. His mental status was slightly drowsy. On hospitalization day 2, the patient experienced respiratory arrest with apnea. Brain magnetic resonance imaging revealed bilateral symmetric T2-high signal lesions without enhancement in the posterior aspect of the brainstem and left medial temporal lobe. Electroencephalography was indicative of diffuse cerebral dysfunction with diffuse high amplitude and irregular delta activities. He underwent a gene study and was diagnosed with myoclonic epilepsy with ragged red fibers syndrome. We report a case of EV 71 brainstem encephalitis by polymerase chain reaction for nasopharyngeal aspirates and feces with rapid progression within one day of fever without the manifestation of throat and skin lesions because of his underlying mitochondrial disease.

• The korean journal of orthodontics
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• v.53 no.5
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• pp.317-327
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• 2023

Objective: This study aimed to evaluate the association between low tongue position (LTP) and the volume and dimensions of the nasopharyngeal, retropalatal, retroglossal, and hypopharyngeal segments of the upper airway. Methods: A total of 194 subjects, including 91 males and 103 females were divided into a resting tongue position (RTP) group and a LTP group according to their tongue position. Subjects in the LTP group were divided into four subgroups (Q1, Q2, Q3, and Q4) according to the intraoral space volume. The 3D slicer software was used to measure the volume and minimum and average cross-sectional areas of each group. Airway differences between the RTP and LTP groups were analyzed to explore the association between tongue position and the upper airway. Results: No significant differences were found in the airway dimensions between the RTP and LTP groups. For both retropalatal and retroglossal segments, the volume and average cross-sectional area were significantly greater in the patients with extremely low tongue position. Regression analysis showed that the retroglossal airway dimensions were positively correlated with the intraoral space volume and negatively correlated with A point-nasion-B point and palatal plane to mandibular plane. Males generally had larger retroglossal and hypopharyngeal airways than females. Conclusions: Tongue position did not significantly influence upper airway volume or dimensions, except in the extremely LTP subgroup.

• The korean journal of orthodontics
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• v.53 no.6
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• pp.358-364
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• 2023

Objective: This study aimed to three-dimensionally evaluate the pharyngeal airway space (PAS) of patients with anterior open bite (AOB) by using cone-beam computed tomography (CBCT) and compare the findings with those obtained in individuals with normal occlusion. Methods: The open bite group (OBG, n = 25) consisted of patients with an anterior overbite of -3 mm or less, while the control group (n = 25) consisted of age- and sex-matched individuals with an anterior overbite of 1-3 mm, Angle Class I malocclusion (1° ≤ point A-nasion-point B angle ≤ 4°), and a normodivergent profile (22° ≤ Frankfort mandibular plane angle ≤ 28°). After the CBCT data were reconstructed into a three-dimensional image, the PAS was segmented into four parts, and the volume of each part was measured. Pharyngeal airway length (PAL) and the area and transverse width of the part showing minimal constriction were also measured. Pearson's correlation analysis was used to evaluate the correlation between changes in the PAS and the amount of anterior overbite. Results: The OBG showed a significantly narrower airway space in the nasopharyngeal, hypopharyngeal, and total airway volumes. The OBG also showed a significantly smaller area and transverse width of the part with minimal constriction. The OBG showed a significantly longer PAL, but there was no correlation between the amount of anterior overbite and the changes in PAS. Conclusions: The PAS was associated with AOB. Patients with AOB had a narrower PAS and a smaller part showing minimal constriction.

• Tuberculosis and Respiratory Diseases
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• v.73 no.5
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• pp.266-272
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• 2012

Background: Limited data on the incidence and clinical characteristics of adult pertussis infections are available in Korea. Methods: Thirty-one hospitals and the Korean Centers for Disease Control and Prevention collaborated to investigate the incidence and clinical characteristics of pertussis infections among adults with a bothersome cough in non-outbreak, ordinary outpatient settings. Nasopharyngeal aspirates or nasopharyngeal swabs were collected for polymerase chain reaction (PCR) and culture tests. Results: The study enrolled 934 patients between September 2009 and April 2011. Five patients were diagnosed as confirmed cases, satisfying both clinical and laboratory criteria (five positive PCR and one concurrent positive culture). Among 607 patients with cough duration of at least 2 weeks, 504 satisfied the clinical criteria of the US Centers for Disease Control and Prevention (i.e., probable case). The clinical pertussis cases (i.e., both probable and confirmed cases) had a wide age distribution ($45.7{\pm}15.5$ years) and cough duration (median, 30 days; interquartile range, 18.0~50.0 days). In addition, sputum, rhinorrhea, and myalgia were less common and dyspnea was more common in the clinical cases, compared to the others (p=0.037, p=0.006, p=0.005, and p=0.030, respectively). Conclusion: The positive rate of pertussis infection may be low in non-outbreak, ordinary clinical settings if a PCR-based method is used. However, further prospective, well-designed, multicenter studies are needed.