A Case of Pediatric Follicular Lymphoma in the Parotid Gland / 대한이비인후과학회지

Pediatric follicular lymphoma (PFL) is rare, and it has distinctive characteristics compared to adult-type follicular lymphoma. PFL mainly occurs in males and is likely to be localized to cervical lymph nodes and tonsils. Extranodal type PFL also occurs in the testis, epididymis, skin, gastrointestinal tract, and parotid gland, etc. The prognosis of PFL is better than adulttype follicular lymphoma. Surgical excision is a good option, and the majority of PFL cases show complete remission after surgery. We have encountered a case of PFL of the parotid gland in a 12-year-old boy. Here, we report this case with a review of the literature.

Surgical Experience of Primary Hyperparathyroidism: Analysis of Postoperative Outcomes / 대한이비인후과학회지

Background and Objectives@#The standard surgical procedure for primary hyperparathyroidism is the bilateral exploration. However, the unilateral exploration and direct focused parathyroidectomy have been performed to reduce surgical morbidity. The purpose of this study was to report the surgical outcomes and efficacy of the bilateral exploration, unilateral exploration, and direct focused approaches for primary hyperparathyroidism.Subjects and Method We retrospectively analyzed the surgical outcomes of 87 patients with primary hyperparathyroidism from January 2007 to December 2017. We compared the operative time, complication and recurrence rate between the three operative methods. @*Results@#The most common histopathology was parathyroid adenoma, which was found in 73 cases (83.9%), followed by hyperplasia. In terms of complications, there were two cases of transient vocal cord palsy, one case of hematoma, one case of hypocalcemia and one case of hungry bone syndrome. Recurrence occurred in two (2.3%) out of 87 cases. There was no significant difference in the recurrence rate between the three surgical approaches. @*Conclusion@#The success rate of surgery for primary hyperparathyroidism is high. Direct focused parathyroidectomy may be a good option for parathyroid adenoma if the localization tests localize the lesion. The bilateral exploration is effective for parathyroid hyperplasia.

Risk Factors and Clinical Features of Recurrent Benign Paroxysmal Positional Vertigo / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Benign paroxysmal positional vertigo (BPPV) is treated with appropriate canalith repositioning procedures, which are very effective for the treatment of BPPV. Nevertheless, the recurrence of BPPV may occur after the initial successful treatment. The purpose of this study was to investigate the risk factors and clinical features of recurrent BPPV. SUBJECTS AND METHOD: The retrospective study was performed for 227 patients who were diagnosed with BPPV and treated with appropriate canalith repositioning procedures from March 2013 to December 2014. We analyzed various clinical characteristics, locations and types of canalith for the whole BPPV patients, and the interval and frequency of recurrence in the patients of recurrent BPPV. RESULTS: Of the total of 227 BPPV patients, 47 patients were recurrent BPPV (21%). The patients of recurrent BPPV were significantly older than those of non-recurrent BPPV (p=0.034). BPPV patients recurred more with increased age, with the significantly increased frequency of recurrence (p=0.010). Twenty two patients were posterior semicircular canal canalolithiasis (PSCC) (46.8%) and 25 patients were lateral semicircular canal canalolithiasis (LSCC) (53.2%). The number of canalith repositioning procedures was significantly higher in LSCC patients than in PSCC patients (p=0.041). The location change of affected canal were identified for 23 patients and the type change of LSCC to ipsilateral PSCC was the most common. CONCLUSION: Age is an important prognostic factor to be considered in BPPV recurrence. Also, the affected semicircular canals were frequently changed in the recurrent BPPV.

Role of Helix 8 in Dopamine Receptor Signaling

G protein-coupled receptors (GPCRs) are membrane receptors whose agonist-induced dynamic conformational changes trigger heterotrimeric G protein activation, followed by GRK-mediated phosphorylation and arrestin-mediated desensitization. Cytosolic regions of GPCRs have been studied extensively because they are direct contact sites with G proteins, GRKs, and arrestins. Among various cytosolic regions, the role of helix 8 is least understood, although a few studies have suggested that it is involved in G protein activation, receptor localization, and/or internalization. In the present study, we investigated the role of helix 8 in dopamine receptor signaling focusing on dopamine D1 receptor (D1R) and dopamine D2 receptor (D2R). D1R couples exclusively to Gs, whereas D2R couples exclusively to Gi. Bioinformatic analysis implied that the sequences of helix 8 may affect GPCR-G protein coupling selectivity; therefore, we evaluated if swapping helix 8 between D1R and D2R changed G protein selectivity. Our results suggest that helix 8 is not involved in D1R-Gs or D2R-Gi coupling selectivity. Instead, we observed that D1R with D2R helix 8 or D1R with an increased number of hydrophobic residues in helix 8 relative to wild-type showed diminished β-arrestin-mediated desensitization, resulting in increased Gs signaling.

Risk Factors and Clinical Features of Recurrent Benign Paroxysmal Positional Vertigo / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES@#Benign paroxysmal positional vertigo (BPPV) is treated with appropriate canalith repositioning procedures, which are very effective for the treatment of BPPV. Nevertheless, the recurrence of BPPV may occur after the initial successful treatment. The purpose of this study was to investigate the risk factors and clinical features of recurrent BPPV.SUBJECTS AND METHOD: The retrospective study was performed for 227 patients who were diagnosed with BPPV and treated with appropriate canalith repositioning procedures from March 2013 to December 2014. We analyzed various clinical characteristics, locations and types of canalith for the whole BPPV patients, and the interval and frequency of recurrence in the patients of recurrent BPPV.@*RESULTS@#Of the total of 227 BPPV patients, 47 patients were recurrent BPPV (21%). The patients of recurrent BPPV were significantly older than those of non-recurrent BPPV (p=0.034). BPPV patients recurred more with increased age, with the significantly increased frequency of recurrence (p=0.010). Twenty two patients were posterior semicircular canal canalolithiasis (PSCC) (46.8%) and 25 patients were lateral semicircular canal canalolithiasis (LSCC) (53.2%). The number of canalith repositioning procedures was significantly higher in LSCC patients than in PSCC patients (p=0.041). The location change of affected canal were identified for 23 patients and the type change of LSCC to ipsilateral PSCC was the most common.@*CONCLUSION@#Age is an important prognostic factor to be considered in BPPV recurrence. Also, the affected semicircular canals were frequently changed in the recurrent BPPV.

Comprehensive Analysis of Non-Synonymous Natural Variants of G Protein-Coupled Receptors

G protein-coupled receptors (GPCRs) are the largest superfamily of transmembrane receptors and have vital signaling functions in various organs. Because of their critical roles in physiology and pathology, GPCRs are the most commonly used therapeutic target. It has been suggested that GPCRs undergo massive genetic variations such as genetic polymorphisms and DNA insertions or deletions. Among these genetic variations, non-synonymous natural variations change the amino acid sequence and could thus alter GPCR functions such as expression, localization, signaling, and ligand binding, which may be involved in disease development and altered responses to GPCR-targeting drugs. Despite the clinical importance of GPCRs, studies on the genotype-phenotype relationship of GPCR natural variants have been limited to a few GPCRs such as β-adrenergic receptors and opioid receptors. Comprehensive understanding of non-synonymous natural variations within GPCRs would help to predict the unknown genotype-phenotype relationship and yet-to-be-discovered natural variants. Here, we analyzed the non-synonymous natural variants of all non-olfactory GPCRs available from a public database, UniProt. The results suggest that non-synonymous natural variations occur extensively within the GPCR superfamily especially in the N-terminus and transmembrane domains. Within the transmembrane domains, natural variations observed more frequently in the conserved residues, which leads to disruption of the receptor function. Our analysis also suggests that only few non-synonymous natural variations have been studied in efforts to link the variations with functional consequences.

Recent Progress in Understanding the Conformational Mechanism of Heterotrimeric G Protein Activation

Heterotrimeric G proteins are key intracellular coordinators that receive signals from cells through activation of cognate G protein-coupled receptors (GPCRs). The details of their atomic interactions and structural mechanisms have been described by many biochemical and biophysical studies. Specifically, a framework for understanding conformational changes in the receptor upon ligand binding and associated G protein activation was provided by description of the crystal structure of the β2-adrenoceptor-Gs complex in 2011. This review focused on recent findings in the conformational dynamics of G proteins and GPCRs during activation processes.