Chul Hwang

Pitx2, a β-catenin-regulated transcription factor, regulates the differentiation of outer root sheath cells cultured in vitro

BACKGROUND Beta-catenin exerts its crucial role in hair follicle development and hair growth cycle. Although the importance of Wnt/beta-catenin is well recognized, the downstream effectors of beta-catenin have not been clearly elucidated yet. OBJECTIVE The aim of this study is to identify the beta-catenin-regulated genes in cultured human hair outer root sheath (ORS) cells. METHODS We transduced ORS cells with adenovirus harboring the expression cassette for constitutive active form of beta-catenin, then performed cDNA microarray. RESULTS Overexpression of beta-catenin led to the upregulation of hair cell differentiation markers such as keratin 16 and 17. In addition, the expression of Pitx2, a bicoid-type homeodomain transcription factor, was also increased by overexpression of beta-catenin in ORS cells cultured in vitro. To investigate the potential role of Pitx2, we made the recombinant adenovirus expressing Pitx2, then transduced into the cultured ORS cells. Interestingly, Pitx2 induced the expression of keratin 16 and 17, indicating that Pitx2 activates ORS cells towards the follicular differentiation pathway preferentially. CONCLUSION Our results implicate the potential importance of Pitx2 as a beta-catenin downstream modulator in hair growth control.

Midface Reconstruction With Various Flaps Based on the Angular Artery

PURPOSE Although several methods can be used to perform midface reconstruction, difficulties exist in selecting the appropriate method because of anatomic and functional complexities, donor site morbidities, and poor esthetic results. The purpose of this study was to develop an alternative reconstructive method for the midface using various flaps based on the angular artery. MATERIALS AND METHODS We investigated the relation between the angular artery and its surrounding structures through cadaveric studies and then applied the findings clinically. As a result, we were able to perform reconstruction with a retroangular flap for defects of the lower half of the nose and the lower eyelid. In addition, defects of the upper half of the nose and the medial canthal area were reconstructed by use of island composite nasal flaps. RESULTS The angular artery was reliable as a pedicle whether it was used in an antegrade or retrograde manner. All the wounds were successfully closed, with the exception of minor complications such as partial skin necrosis and flap bulkiness. The esthetic outcomes for the donor and recipient sites were acceptable. CONCLUSION The angular artery has diverse relations with its surrounding structures according to its course of travel, and if the surgeon has a precise understanding of its anatomic location, we believe that retroangular flaps and island composite nasal flaps may prove useful for the treatment of midface defects.

The Role of Nkx2.5 in Keratinocyte Differentiation

BACKGROUND Nkx2.5 is a homeodomain-containing nuclear transcription protein that has been associated with acute T-lymphoblastic leukemia. In addition, Nkx2.5 has an essential role in cardiomyogenesis. However, the expression of Nkx2.5 in the skin has not been investigated. OBJECTIVE In an attempt to screen the differentially regulated genes involved in keratinocyte differentiation, using a cDNA microarray, we identified Nkx2.5 as one of the transcription factors controlling the expression of proteins associated with keratinocyte differentiation. METHODS To investigate the expression of Nkx2.5 during keratinocyte differentiation, we used a calcium-induced keratinocyte differentiation model. RESULTS RT-PCR and Western blot analysis revealed that the expression of Nkx2.5, in cultured human epidermal keratinocytes, increased with calcium treatment in a time-dependent manner. In normal skin tissue, the expression of Nkx2.5 was detected in the nuclei of the keratinocytes in all layers of the epidermis except the basal layer by immunohistochemistry. In addition, the expression of Nkx2.5 was significantly increased in psoriasis and squamous cell carcinoma, but was barely detected in atopic dermatitis and basal cell carcinoma. CONCLUSION These results suggest that Nkx2.5 may play a role in the change from proliferation to differentiation of keratinocytes and in the pathogenesis of skin disease with aberrant keratinocyte differentiation.

A case of unilateral scrotal calcinosis

Scrotal calcinosis usually occurs during adolescence, and appears as asymptomatic hard nodules on the scrotum, which can be single or multiple. The nodules usually occur bilaterally, and usually increase in number over time. Unilateral scrotal calcinosis has not been reported previously in the dermatological literature, to our knowledge. We report a peculiar case of scrotal calcinosis, in which 20 nodules were limited to the left scrotum. They ranged in size from 2 to 10 mm. Over 2 months, they decreased slightly in size and number, and no new nodules developed. In April 2006, an 18-year-old man was admitted to our department with multiple subcutaneous nodules on the left scrotum that had occurred 1 month earlier. He reported that the number and size of the nodules had increased and were causing discomfort. On physical examination, 20 nodules ranging in size from 2 to 10 mm were seen (Fig. 1a). Histological examination of a skin biopsy specimen found amorphous basophilic calcium nodules in the dermis with no epidermal change (Fig. 1b). No epithelial lining or inflammatory cells were seen. The patient was in good health and claimed to have no underlying disease. He refused to undergo blood, urine or radiological tests. He was followed up carefully for 2 months, during which time the subcutaneous nodules decreased slightly in size and number (Fig. 1c). Scrotal calcinosis was first reported by Lewinski in 1883. It usually occurs during adolescence, appearing as a single nodule or multiple asymptomatic hard nodules, which can reach 30 mm in size, on the scrotum. Scrotal calcinosis is typically bilateral, and the number of nodules increases over time, with reported cases involving up to 51 nodules. Histopathological observations of scrotal calcinosis include amorphous basophilic calcium nodules on haematoxylin and eosin staining. With von Kossa stain, the nodules stain black. Some nodules have an epithelial lining. In addition, multinucleated megakaryocytes and inflammatory cells may be seen around the calcium deposits. Destruction of the nodules may result in the efflux of a chalk-like substance. The aetiopathogenesis of the disease remains controversial. Although no reports in the English literature have (a)

Multimedia data parsing and reassembling for the zCAS (Collaborative-works Assistant System) under group environments

Multimedia data have a huge volume, that give rise to problems for real-time cooperative-work services, such as media sharing, media browsing, network traffic and delay control, and the user response for media processing. Many research activities have improved the service quality, but these approaches are file-based. Our method is not a file-based but a segment-based processing. In this study, the proposed model solves these problems using media segmentation by considering the logical characteristics of the media. Therefore, we propose the segmentation of the media and methods of reassembling the segments. The zCAS, which is a groupware platform, has been developed for the real-time multimedia cooperative-work services with segments. The proposed system is characterized for group-supported services; the content-based synchronization of presentation and browsing, the media sharing among the users in a domain group, and the effective use of communication networks.

Pearls and Pitfalls in Pediatric Imaging: Branchio-oto-renal syndrome

Branchio-oto-renal (BOR) syndrome is a rare congenital anomaly that is characterized by preauricular pits, branchial fistula and hearing impairment and it is often combined with renal anomalies. BOR syndrome is inherited in an autosomal dominant mode and the mutations of two genes, EYA1 and SIX1, have been identified. We experienced a case of a 14-year-old female who complained of bilateral neck openings and hearing loss that were found at birth the girl’s family had a familial tendency for these features. A skin biopsy from the cervical lesion showed the characteristic features of branchial fistula. We report here on a case of BOR syndrome and we review the relevant literature.