Biomedical subjects

Y M Chun

Publications and source records attributed to Y M Chun.

7 recordsLinked to original sources

PubMed2001

Immunohistochemical study on proliferative activity of experimental cholesteatoma.

In this study, we induced canal ligation cholesteatoma using Mongolian gerbils and investigated the hyperproliferative nature of canal ligation cholesteatoma by using an immunohistochemical technique with proliferation markers (cytokeratin 13/16, PCNA, EGFR, thrombomodulin). Canal ligation cholesteatoma using Mongolian gerbils had a hyperproliferative character in the suprabasal cell layer similar to human cholesteatomas. This result will provide a good morphological basis for future cholesteatoma animal research concerning the pathogenesis of cholesteatoma.

Animals↗

PubMed2001

Expression of phospholipase C-gamma1 in experimental cholesteatoma using Mongolian gerbils.

Phospholipase C (PLC)-gamma1 is known to play a central role in ligand-mediated signal transduction for cell proliferation. The purpose of this study was to elucidate the distribution of PLC-gamma1 in deep meatal skin, retroauricular skin and cholesteatoma matrix of experimental animals. We induced canal ligation cholesteatoma using Mongolian gerbils and investigated the expression of PLC-gamma1 in this model by using Western blot analysis and immunohistochemistry. By Western blot analysis, considerably higher levels of PLC-gamma1 protein were detectable in experimental cholesteatoma. On immunohistochemistry, experimental cholesteatoma showed more intense immunolabeling of PLC-gamma1 protein than deep meatal skin and retroauricular skin. In conclusion, overexpression of PLC-gamma1 may in part contribute to abnormal proliferation and differentiation of experimental cholesteatoma in Mongolian gerbils.

Animals↗

PubMed2000

Cell biology of tubotympanum in relation to pathogenesis of otitis media - a review.

The sterility of the eustachian tube and tympanic cavity of normal individuals is maintained not only by the adaptive immune system, but also by the mucociliary system and the antimicrobial molecules of innate immunity. Mucin production and periciliary fluid homeostasis are essential for normal mucociliary function and dysfunction of this system is an important risk factor for otitis media. The secreted antimicrobial molecules of the tubotympanum include lysozyme, lactoferrin, beta defensins, and the surfactant proteins A and D (SP-A, SP-D). Defects in the expression or regulation of these molecules may also be the major risk factor for otitis media.

Animals↗

PubMed2000

Epithelial differentiation in developing murine eustachian tube and middle ear.

Detailed information on how an epithelial differentiation occurred in the developing eustachian tube and middle ear would be helpful in understanding both normal physiology and pathology of the tubotympanum. This study was undertaken to establish patterns of laminin and E-cadherin in the embryonic mouse eustachian tube and middle ear by use of immunohistochemistry at a stage when epithelial differentiation is taking place. This study was also designed to clarify the role of the middle ear mesenchyme. During the development of the eustachian tube, relatively high immunoreactivity to laminin was observed in the epithelium at gestational days 16 and 17, when the developments of ciliated and secretory cells were first observed. At the time of birth, in contrast to epithelium of the eustachian tube, epithelium of the middle ear cavity showed predominant expression of laminin and E-cadherin. These findings suggest that the expressions of laminin and E-cadherin may be correlated with maturation of the epithelium in the eustachian tube and middle ear and that the epithelial differentiation of the developing murine eustachian tube and middle ear may be controlled by epithelial-mesenchymal interaction and cell-to-cell interaction.

Animals↗

PubMed2000

Connexin26 mutations associated with nonsyndromic hearing loss.

OBJECTIVE: Mutations in the GJB2 gene are a major cause of autosomal recessive and sporadic types of congenital deafness. The 35delG mutation is the most frequent type of mutation in white populations. However, several other forms were reported, such as 167delT among Ashkenazi Jews and R143W in Africans. The present study investigated the mutations of connexin26 (Cx26) found in patients with nonsyndromic hearing loss (NSHL) and newborns in the Korean population. STUDY DESIGN: The sequencing data for 147 unrelated patients with congenital NSHL and 100 audiologically screened newborns were included in this prospective study. METHODS: Genomic DNA samples from all patients and newborns were sequenced in both directions for detection of Cx26 mutations. RESULTS: Thirteen different types of mutations were found in the patients and newborns. V27I and E114G are the popular types of polymorphic mutations in both groups. 235delC-deletion and frameshift--was detected in patients (15 in 294 alleles) and newborns (1 in 200 alleles). 35delG was rarely found in both group. In addition to above mutations, several types of mutations--S85P, K41R, S72C, V84A, 176-191del, and 299-300del-were identified. The family study of the 235delC showed a typical autosomal recessive trait of NSHL in their audiological evaluation of hearing threshold. CONCLUSION: The frequency of 235delC allele showed much higher in the patients (5%) than in newborns (0.5%). We rarely found 35delC mutant in both groups. These results suggest that the different types of Cx26 mutations affect autosomal recessive NSHL according to ethnic background.

Adult↗

PubMed1999

Immunohistochemical study of cell proliferation using BrdU labelling on tympanic membrane, external auditory canal and induced cholesteatoma in Mongolian gerbils.

The Mongolian gerbil is a well-known animal model for induction of aural cholesteatomas. This animal model is useful for studying changes in the keratinizing epithelium. It is not known whether keratin accumulation can increase the proliferative activity of the keratinizing epithelium in tympanic membrane and meatal skin. In this study, we investigated the proliferative activity of the epidermis in induced aural cholesteatoma at various stages and in different areas of the tympanic membrane and meatal skin in normal gerbils. Anti-5-bromo-2- deoxyuridine (BrdU) was injected intraperitoneally to detect the proliferative activity of keratinizing epithelium. Immunohistochemistry with monoclonal BrdU antibody in the normal gerbil showed intense immunolabelled keratinocytes at the handle of malleus, and the superior parts of pars tensa and pars flaccida. Also, mitotic activity in the deep meatal skin was more active than in the lateral meatal skin. The induced aural cholesteatoma showed more active proliferation centre of the epithelial cell than eardrum and external ear canal of the normal gerbil. These observations suggest that the accumulation of the keratin debris might induce changes of the cellular proliferation in the external auditory meatus.

Animals↗

PubMed1987

Laryngeal pacemaker using a temperature sensor in the canine.

With the use of a temperature sensor that would detect temperature changes during the respiratory cycle in the pharynx, electrical stimulation of the posterior cricoarytenoid muscle was achieved in dogs whose recurrent laryngeal nerves were artificially paralyzed. Due to the temperature difference between inspiratory and expiratory air flow, a trigger pulse was generated at the beginning of inspiration. The stimulation pulse following the trigger pulse stimulated the electrodes inserted into the posterior cricoarytenoid muscles. In all five canines, obvious abduction of the vocal folds synchronized with inspiration was observed during electrical pacing.

Animals↗