Tae-Jun Kwon

Cranial nerve injury after Le Fort I osteotomy

A Le Fort I osteotomy is widely used to correct dentofacial deformity because it is a safe and reliable surgical method. Although rare, various complications have been reported in relation to pterygomaxillary separation. Cranial nerve damage is one of the serious complications that can occur after Le Fort I osteotomy. In this report, a 19-year-old man with unilateral cleft lip and palate underwent surgery to correct maxillary hypoplasia, asymmetry and mandibular prognathism. After the Le Fort I maxillary osteotomy, the patient showed multiple cranial nerve damage; an impairment of outward movement of the eye (abducens nerve), decreased vision (optic nerve), and paraesthesia of the frontal and upper cheek area (ophthalmic and maxillary nerve). The damage to the cranial nerve was related to an unexpected sphenoid bone fracture and subsequent trauma in the cavernous sinus during the pterygomaxillary osteotomy.

Methionine Sulfoxide Reductase B3-Targeted In Utero Gene Therapy Rescues Hearing Function in a Mouse Model of Congenital Sensorineural Hearing Loss.

AIMSnMethionine sulfoxide reductase B3 (MsrB3), which stereospecifically repairs methionine-R-sulfoxide, is an important Msr protein that is associated with auditory function in mammals. MsrB3 deficiency leads to profound congenital hearing loss due to the degeneration of stereociliary bundles and the apoptotic death of cochlear hair cells. In this study, we investigated a fundamental treatment strategy in an MsrB3 deficiency mouse model and confirmed the biological significance of MsrB3 in the inner ear using MsrB3 knockout (MsrB3(-/-)) mice.nnnRESULTSnWe delivered a recombinant adeno-associated virus encoding the MsrB3 gene directly into the otocyst at embryonic day 12.5 using a transuterine approach. We observed hearing recovery in the treated ears of MsrB3(-/-) mice at postnatal day 28, and we confirmed MsrB3 mRNA and protein expression in cochlear extracts. Additionally, we demonstrated that the morphology of the stereociliary bundles in the rescued ears of MsrB3(-/-) mice was similar to those in MsrB3(+/+) mice.nnnINNOVATIONnTo our knowledge, this is the first study to demonstrate functional and morphological rescue of the hair cells of the inner ear in the MsrB3 deficiency mouse model of congenital genetic sensorineural hearing loss using an in utero, virus-mediated gene therapy approach.nnnCONCLUSIONnOur results provide insight into the role of MsrB3 in hearing function and bring us one step closer to hearing restoration as a fundamental therapy.

Accuracy of maxillary repositioning in two-jaw surgery with conventional articulator model surgery versus virtual model surgery

The purpose of this study was to compare the accuracy of maxillary repositioning using the recently introduced computerized virtual model surgery (VMS) with conventional articulator model surgery (AMS). Forty-two patients who had undergone bimaxillary surgery were investigated retrospectively in this study. The patients were divided into two groups: conventional AMS (n = 23) and VMS (n = 19) for intermediate splint fabrication in maxillary positioning. Planned surgical movements and actual postsurgical changes of the lateral and frontal cephalometric measurements were compared. Although variations from the planned surgical movements were relatively small, both methods had statistically significant errors in some of the linear measurements. Both groups had a similar range of errors. The overall absolute mean discrepancy between the planned and actual surgical movements for the linear measurements was 1.17 mm (0-3.6 mm) in AMS and 0.95 mm (0-3.2 mm) in VMS. Of the total measurements, measurements reflecting a surgical discrepancy of more than 2 mm or 2° comprised 12.0% of the cases in AMS and 7.9% in VMS. The surgical accuracy of maxillary positioning with VMS was comparable to conventional AMS. Because VMS has the definitive advantage of eliminating the complex laboratory step and shortening the laboratory time, this can be accepted as an alternative to AMS.

Three-dimensional soft tissue change after paranasal augmentation with porous polyethylene

The aim of this study was to investigate the effect of porous polyethylene (PPE) in paranasal augmentation on midfacial soft tissue architecture. This retrospective study recruited patients with midface retrusion and mandibular prognathism. Twenty adult patients who had undergone bilateral PPE augmentation (ready-made type, thickness 4.5mm, Medpor) to the piriform aperture and simultaneous mandibular setback surgery were included in this study. The soft tissue morphology and thickness of the midface were evaluated using three-dimensional reformatted images from cone beam computed tomography done before and 6 months after surgery. The soft tissue outline of the midface was augmented 1-4mm. The average increase in soft tissue outline near the peri-alar region was 3.1-3.4mm, which comprised 68-74% of the PPE thickness (P<0.01). The nasolabial angle and columellar inclination were increased significantly (2.2° and 1.4°, respectively; both P<0.05), whereas the nasal tip angle, nasal tip protrusion, columellar length, and bilateral nostril axis angle did not change. The alar base became wider on average by 2.2mm (P<0.01). The results showed that paranasal augmentation with PPE significantly increased the overlying soft tissue outline without influencing the nasal projection and could enhance paranasal aesthetics with minimal morbidity.

Functional mapping of the auditory tract in rodent tinnitus model using manganese-enhanced magnetic resonance imaging

Animal models of salicylate-induced tinnitus have demonstrated that salicylate modulates neuronal activity in several brain structures leading to neuronal hyperactivity in auditory and non-auditory brain areas. In addition, these animal tinnitus models indicate that tinnitus can be a perceptual consequence of altered spontaneous neural activity along the auditory pathway. Peripheral and/or central effects of salicylate can account for neuronal activity changes in salicylate-induced tinnitus. Because of this ambiguity, an in vivo imaging study would be able to address the peripheral and/or central involvement of salicylate-induced tinnitus. Therefore, in the present study, we developed a novel manganese-enhanced magnetic resonance imaging (MEMRI) method to map the in vivo functional auditory tract in a salicylate-induced tinnitus animal model by administrating manganese through the round window. We found that acute salicylate-induced tinnitus resulted in higher manganese uptake in the cochlea and in the central auditory structures. Furthermore, serial MRI scans demonstrated that the manganese signal increased in an anterograde fashion from the cochlea to the cochlear nucleus. Therefore, our in vivo MEMRI data suggest that acute salicylate-induced tinnitus is associated with higher spontaneous neural activity both in peripheral and central auditory pathways.

Soft tissue changes and skeletal stability after modified quadrangular Le Fort I osteotomy.

The purpose of this study was to evaluate the soft tissue changes and skeletal stability of a modification of the Le Fort I osteotomy design - the modified quadrangular Le Fort I osteotomy (MQLI). Patients who had maxillary advancement and mandibular setback surgery for skeletal class III malocclusion with a midface deficiency were included. MQLI patients (n=20) were compared to conventional Le Fort I osteotomy patients (LFI) (n=20) using cephalometric radiographs taken preoperatively (T0), immediately postoperative (T1), and at >6 months postoperative (T2). Soft tissue radiographic changes of the cheek line and perinasal areas, and skeletal movements were analyzed. The basic skeletal characteristics and amount of maxillary and mandibular surgical change were similar in the two groups (group difference, P>0.05). There was no significant difference between the two groups in terms of maxillary and mandibular skeletal stability. The cheek profile angle increased significantly after MQLI by 3.5° (P<0.05), whereas LFI showed a 2.1° increase (P>0.05). Overall, the soft tissue cheek outline moved significantly more anteriorly in MQLI, but the difference to LFI osteotomy did not reach statistical significance. MQLI could be an efficient and stable surgical method to improve maxillary and infraorbital hypoplasia without malar advancement, especially in Asian patients.

Molecular cloning, characterization, and expression of pannexin genes in chicken

Pannexins (Panx) are a family of proteins that share sequences with the invertebrate gap junction proteins, innexins, and have a similar structure to that of the vertebrate gap junction proteins, connexins. To date, the Panx family consists of 3 members, but their genetic sequences have only been completely determined in a few vertebrate species. Moreover, expression of the Panx family has been reported in several rodent tissues: Panx1 is ubiquitously expressed in mammals, whereas Panx2 and Panx3 expressions are more restricted. Although members of the Panx family have been detected in mammals, their genetic sequences in avian species have not yet been fully elucidated. Here, we obtained the full-length mRNA sequences of chicken PANX genes and evaluated the homology of the amino acids from these sequences with those of other species. Furthermore, PANX gene expression in several chicken tissues was investigated based on mRNA levels. PANX1 was detected in the brain, cochlea, chondrocytes, eye, lung, skin, and intestine, and PANX2 was expressed in the brain, eye, and intestine. PANX3 was observed in the cochlea, chondrocytes, and bone. In addition, expression of PANX3 was higher than PANX1 in the cochlea. Immunofluorescent staining revealed PANX1 in hair cells, as well as the supporting cells, ganglion neurons, and the tegmentum vasculosum in chickens, whereas PANX3 was only detected in the bone surrounding the cochlea. Overall, the results of this study provide the first identification and characterization of the sequence and expression of the PANX family in an avian species, and fundamental data for confirmation of Panx function.

Methionine Sulfoxide Reductase A, B1 and B2 Are Likely to Be Involved in the Protection against Oxidative Stress in the Inner Ear

The methionine sulfoxide reductase (Msr) family of proteins is a class of repair enzymes that reduce methionine-S (MsrA) or methionine-R (MsrB) sulfoxide to methionine. Recent studies have reported that mutations in the MSRB3 gene cause autosomal recessive hearing loss in humans, and in mice MsrB3 deficiency leads to profound hearing loss due to hair cell apoptosis and stereocilia degeneration. However, apart from MsrB3, studies on Msr proteins in the inner ear have not yet been reported. In this study, we identified and characterized Msr expression in the cochlea and vestibule. First, we confirmed RNA expression levels of Msr family members in the cochlea and vestibule using reverse transcription PCR and detected Msr family members in both tissues. We also conducted immunohistochemical staining to localize Msr family members within the cochlea and vestibule. In the cochlea, MsrA was detected in supporting cells, spiral ligament, spiral limbus, Reissners membrane and the spiral ganglion. MsrB1 was specifically expressed in hair cells and the spiral ganglion. MsrB2 was noted in the spiral ganglion, tectorial membrane and stria vascularis. In the vestibule, MsrA and MsrB1 were detected in hair cells and the vestibular ganglion, while MsrB2 was restricted to the vestibular ganglion. In this study, we identified distinct distributions of Msr family members in the organ of Corti and hypothesized that MsrA, MsrB1 and MsrB2 protect proteins in the organ of Corti from oxidative stress.

Histopathological and scanning electron microscopy findings of retrieved porous polyethylene implants

Porous polyethylene (PPE) implants are biocompatible alloplastic materials commonly used for facial augmentation. However, the effect of sub-periosteal PPE application on the surrounding tissues has not been analyzed clearly. This report documents the case of a 22-year-old woman who underwent peri-alar augmentation with PPE to improve midface retrusion. Although no infection or inflammation occurred at the surgical site, the patient requested removal of the PPE implant for aesthetic reasons alone at 1 year after the surgery. The removed implant was subjected to histological and morphological evaluation using conventional histological staining and scanning electron microscopy (SEM). Histopathological staining revealed bone ingrowth into the pores of the implant near the boundary with the host bone. Little evidence of a foreign body reaction was observed. SEM revealed densely arranged collagen fibres and osteoblastic cells in the pores. Moreover, the outer surface of the PPE implant in contact with the periosteum showed fibrous tissue ingrowth, leading to tissue adhesion. These findings confirm bone ingrowth into the PPE pore structure in humans.

Polymorphisms of TAS1R3 and GNAT3 Genes Are Associated with Patients with Taste Disorder

Taste sensation plays a crucial role in selecting and ingesting foods with different qualities which convey information about their nutrient content and/or safety. Sweetness is one of the five modalities in humans and serves as an energy resource for metabolism. There are reports on allelic polymorphisms which influence perception of sweetness in mice and humans. Since the influence of genetic factors on taste disorder has not been studied, we investigated the association of genetic polymorphisms in TAS1R3 and guanine nucleotide binding protein, alpha transducing 3 (GNAT3) genes and taste disorder. A total of 150 individuals composed of 50 patients with taste disorder and 100 healthy controls were recruited for the study and PCR-mediated directing sequencing method was used to genotype for two different single nucleotide polymorphisms (SNPs) - rs307355 (T>C) and rs35744813 (T>C) in the TAS1R3 gene, and rs7792845 (T>C) and rs1524600 (C>T) in the the GNAT3 gene. The allele and genotype frequencies of rs307355 and rs35744813 in the TAS1R3 gene showed a significant association between patients with taste disorder (p