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Biomedical subjects

J H Choi

Publications and source records attributed to J H Choi.

At least 127 records · Page 7Linked to original sources
PubMed2000

Selective involvement of reactive oxygen intermediates in platelet-activating factor-mediated activation of NF-kappaB.

Although it has been suggested that some biological activities of platelet-activating factor (PAF) are mediated by, at least in part, reactive oxygen intermediates (ROI), the precise mechanisms underlying the interaction between the two remains to be elucidated. Antioxidants, such as alpha-tocopherol acid succinate, N-acetyl-L-Cysteine, pyrrolidinedithiocarbamate failed to inhibit PAF-induced immediate systemic reactions such as lethality, symptoms of disseminated intravascular coagulation, and histological changes such as pulmonary edema and hemorrhage in renal medullae 10 min following PAF injection. In contrast. antioxidants significantly inhibited both the in vivo and in vitro PAF-induced NF-kappaB activation and NF-kappaB-dependent TNF-alpha expression. The effects of the antioxidants were due to their inhibition of PAF-induced degradation of IkappaBalpha, a protein responsible for keeping NF-kappaB in an inactive form. A protein tyrosine kinase and N-tosyl-L-phenylalanine chloromethyl ketone sensitive serine protease were involved in both PAF- and H2O2-induced NF-kappaB activation. Collectively, these data indicate that the PAF-induced NF-kappaB activation is selectively mediated through the generation of ROI.

Acetylcysteine↗
PubMed2000

Bioconversion of D-galactose into D-tagatose by expression of L-arabinose isomerase.

D-Tagatose is a potential bulking agent in food as a non-calorific sweetener. To produce D-tagatose from cheaper resources, plasmids harbouring the L-arabinose isomerase gene (araA) from Escherichia coli, Bacillus subtilis and Salmonella typhimurium were constructed because L-arabinose isomerase was suggested previously as an enzyme that mediates the bioconversion of galactose into tagatose as well as that of arabinose to ribulose. The constructed plasmids were named pTC101, pTC105 and pTC106, containing araA from E. coli, B. subtilis and S. typhimurium respectively. In the cultures of recombinant E. coli with pTC101, pTC105 and pTC106, tagatose was produced from galactose in 9.9, 7.1 and 6.9% yields respectively. The enzyme extract of E. coli with the plasmid pTC101 also converted galactose into tagatose with a 96.4% yield.

Aldose-Ketose Isomerases↗
PubMed2000

A case of guttate psoriasis following Kawasaki disease.

We report a case of guttate psoriasis following Kawasaki disease, in a patient with Staphylococcus aureus demonstrated in a throat swab. We suggest that preceding staphylococcal infection can play a key role in the pathogenesis of some cases of guttate psoriasis, possibly by the production of superantigens.

Disease Progression↗
PubMed2000

Viral folliculitis on the face.

The common clinical presentations of herpes simplex virus (HSV) and molluscum contagiosum (MC) are well known to dermatologists. However, folliculitis due to these viruses is an infrequently reported entity and might be considered a sign of immunosuppression [such as infection with human immunodeficiency virus, (HIV)], especially in cases of folliculitis due to MC. The purpose of this study was to describe the clinical and histopathological characteristics of viral folliculitis due to HSV and MC. We retrospectively collected all our cases with histologically proven folliculitis due to HSV and MC between 1994 and 1999. A total of seven patients aged 7-54 years was identified. Prior to establishment of the diagnosis of folliculitis due to HSV and MC, they were treated with topical antibiotics or topical steroids, without improvement. Tentative diagnoses were bacterial folliculitis, syringoma, perifollicular fibrosis, contact dermatitis or pseudolymphoma. Biopsy of the lesions revealed multiple molluscum bodies in the follicular epithelium with sparing of the epidermis in four patients, and ballooning degeneration and intranuclear viral inclusions in the follicular epithelium in the other three. Three patients had evidence of underlying immune suppression, such as pregnancy, chronic viral hepatitis B and nasopharyngeal carcinoma. One patient had suffered from epilepsy for 4 years. Testing for HIV by enzyme-linked immunosorbent assay was negative in the four patients in whom this was performed, and T-cell subsets were normal in the three patients in whom these were quantified. In cases of molluscum folliculitis treated with simple curettage, the lesions cleared without scarring or recurrence. In cases of herpetic folliculitis, the lesions improved with antihistamines or acyclovir. MC or HSV should be considered in cases that present with folliculitis-like dermatoses but which are refractory to anti-infective and anti-inflammatory treatment.

Adolescent↗
PubMed2000

CD56 expression in a case of primary cutaneous CD30+ anaplastic large cell lymphoma.

We describe clinicopathological features of an unusual case of CD30+/CD56+ T-cell lymphoma in a 58-year-old Korean man who presented with disseminated nodules, papules and hyperpigmented patches. Coexpression of CD30 and CD56 in T-cell lymphoma is very rare. Our patient did not respond to an intensive chemotherapy regimen, in contrast to the previously reported cases of primary cutaneous CD30+ anaplastic large cell lymphoma. Coexpression of CD56 might therefore identify a subset of CD30+ lymphomas with more aggressive features.

Antigens, Neoplasm↗
PubMed2000

Clinicopathological features of CD56+ nasal-type T/natural killer cell lymphomas with lobular panniculitis.

Nasal-type T/natural killer cell lymphoma (TNKCL) shows frequent extranodal involvement including the skin, and is associated with a poor prognosis. We have studied six patients with nasal-type TNKCL presenting with inflammatory subcutaneous nodular lesions with a subcutaneous lymphoid infiltrate. Clinical information was obtained from the medical records of the patients and at follow-up. All cases showed features of angiocentric lymphoma on histology, although there was diffuse cellular infiltration rather than an angiocentric pattern in the subcutis. All six patients were similar in immunophenotype: positive for CD56 and either cytoplasmic CD3 or CD45RO, but negative for B-cell markers and CD30. In situ hybridization using an anti-sense Epstein-Barr virus early regions probe showed a positive reaction in all cases. All patients either died with progressive disease or showed no response to combined chemotherapy. The diagnosis of nasal-type TNKCL, which has a fatal outcome, is facilitated by detection of CD56-positive tumour cells. In evaluating lobular panniculitis including apparently benign inflammatory subcutaneous nodules, nasal-type TNKCL should be considered in the differential diagnosis, especially in Asian countries.

Adult↗
PubMed2000

Nasal and nasal type CD56+ natural killer cell/T-cell lymphoma: a case with rapid progression to bone marrow involvement.

We describe herein a case of CD56+ natural killer cell lymphoma (NKCL) that showed unusual clinical manifestations and a fulminant course of disease. A 70-year-old male patient presented with rapidly growing skin lesions and fever; a nasal lymphoma was subsequently detected and bone marrow involvement developed within a few weeks. Although the time relationship is not clear, bone marrow involvement could be dissemination from localized disease of nasal and nasal type NKCL. As seen in our case, the course can be excessively aggressive and fulminant even when it first appeared as a localized disease, and CD56 positivity, which is a specific characteristic of NKCL, may serve as a factor showing a poor prognosis for a malignant lymphoma.

Aged↗
PubMed2000

Linear eruptions of the nose in childhood: a form of lichen striatus?

We report four children with linear eruptions on the nose, with overlapping features of lichen striatus and linear cutaneous lupus erythematosus. However, linear lupus erythematosus has rarely been reported, and lichen striatus, although classically linear, rarely affects the face. The linear distribution of lesions from the glabella to the ala nasi may represent distribution following Blaschko's lines.

Adolescent↗
PubMed2000

T-DNA insertional mutagenesis for functional genomics in rice.

We have produced 22 090 primary transgenic rice plants that carry a T-DNA insertion, which has resulted in 18 358 fertile lines. Genomic DNA gel-blot and PCR analyses have shown that approximately 65% of the population contains more than one copy of the inserted T-DNA. Hygromycin resistance tests revealed that transgenic plants contain an average of 1.4 loci of T-DNA inserts. Therefore, it can be estimated that approximately 25 700 taggings have been generated. The binary vector used in the insertion contained the promoterless beta-glucuronidase (GUS) reporter gene with an intron and multiple splicing donors and acceptors immediately next to the right border. Therefore, this gene trap vector is able to detect a gene fusion between GUS and an endogenous gene, which is tagged by T-DNA. Histochemical GUS assays were carried out in the leaves and roots from 5353 lines, mature flowers from 7026 lines, and developing seeds from 1948 lines. The data revealed that 1.6-2.1% of tested organs were GUS-positive in the tested organs, and that their GUS expression patterns were organ- or tissue-specific or ubiquitous in all parts of the plant. The large population of T-DNA-tagged lines will be useful for identifying insertional mutants in various genes and for discovering new genes in rice.

Base Sequence↗
PubMed2000

Tinea pedis in Korean children.

BACKGROUND: Tinea pedis is an infrequent disease in children before the age of puberty. There are few epidemiologic and clinical data regarding cases of tinea pedis observed in children. Materials and methods We prospectively collected all cases of tinea pedis in children diagnosed during the years 1995-1997. Only those showing a positive result with potassium hydroxide preparation were included in the study. We performed fungal cultures in Sabouraud's agar in all cases to document the etiologic fungi. The clinical characteristics were investigated. RESULTS: A total of 21 children, aged 3 months to 14 years, were included. Fifteen patients were boys and six were girls. The mean age was 7.1 years. All the children were otherwise healthy. Prior to the establishment of the diagnosis of tinea pedis, 17 patients (80.9%) were treated for eczema without improvement. The intertriginous type was most common (53.3%). The first or second toe-webs were the sites of predilection (32.3%). Eighteen children (86%) had a family history of tinea pedis and more than half of cases (52.4%) showed occurrence in the summer. The results of fungal cultures were positive in 13 patients (57%). Trichophyton rubrum was the most commonly isolated pathogen (69.2%). The other associated dermatoses were onychomycosis (33.3%), atopic dermatitis (14%), plantar warts (10%), and chronic urticaria (5%). Tinea pedis and onychomycosis cleared after treatment with topical antifungals with or without systemic antifungals in all cases. CONCLUSIONS: Tinea pedis in children can occur more frequently than suspected. Our study shows the strong association with a family history and the seasonal relationship with occurrence in summer in more than half of cases. We suggest that tinea pedis should be considered in the differential diagnosis of foot dermatitis in children.

Adolescent↗
PubMed2000

Onychomycosis and Trichosporon beigelii in Korea.

BACKGROUND: Onychomycosis is a common superficial fungal infection. Causative organisms in onychomycosis have been extensively studied, but the role of nondermatophytes is controversial. Trichosporon beigelii is a soil and water inhabiting yeast and is occasionally found in the flora normally associated with human skin, mouth, and nails. Several reports in the literature have suggested that T. beigelii is one of the pathogens in onychomycosis. METHODS: We performed a survey of the mycologic laboratory records of patients clinically suspected of having onychomycosis from July 1996 to December 1998. RESULTS: Out of a total of 2591 nail samples examined, 1222 (47.2%) were culture positive, including 262 cases (10.1%) with T. beigelii. The overall positive rate for the KOH mount examination was 58.8%, and in the cases with T. beigelii was 89.1%. Among the age groups, the incidence rate was highest in the fifth decade (26.6%). The most common causative organism of microscopy-positive onychomycosis was Trichophyton rubrum (61.4%); the others in decreasing frequency were T. beigelii (20.4%), Candida spp. (7.3%), Trichophyton mentagrophytes (4.1%), and mixed infection (2.9%). T. beigelii was repeatedly isolated in successive nail cultures from 10 of 20 patients selected from those with T. beigelii nail infection. CONCLUSIONS: T. beigelii was the second most commonly isolated fungus in onychomycosis and had a high positive rate on KOH mount examination of the nails and successive repeated cultures. We suggest that T. beigelii might be a common pathogen of onychomycosis in Korea.

Adolescent↗
PubMed2000

Successful removal of freckles in Asian skin with a Q-switched alexandrite laser.

BACKGROUND: : Although freckles are light-brown macules most frequently observed in individuals with red or blond hair and blue or gray eyes, freckles are common to Asian people, including Koreans. Treatment may be requested on cosmetic grounds. OBJECTIVE: : The objective of this study was to determine the effectiveness of the Q-switched alexandrite laser (wavelength 755 nm; pulse width 100 nsec) in treating the 197 cases of Asian skin with freckles and to observe any side effects such as pigmentary changes or scarring. METHODS: : One hundred ninety-seven patients with freckles were treated with the Q-switched alexandrite laser at 8-week intervals and clinically analyzed. RESULTS: : More than 76% removal of freckles required an average of 1.5 treatment sessions with 7.0 J/cm2. No scarring, long-standing pigmentary changes, or textural changes were seen in laser-irradiated skin. CONCLUSION: : The Q-switched alexandrite laser is a safe and highly effective modality for removing freckles without scarring or permanent pigmentary changes in Asian skin.

Adolescent↗
PubMed2000

Lichenoid keratosis: a clinicopathologic study of 17 patients.

BACKGROUND: Lichenoid keratosis (LK) is a rather frequent skin lesion that has some histologic features similar to lichen planus (LP). The clinical and histopathologic characteristics of LK and differential tools from LP are not yet fully established. OBJECTIVE: The purpose of this study was to investigate the clinical and histopathologic characteristics of LK. METHODS: A clinical survey was done with 17 patients diagnosed as having LK. We reevaluated biopsy materials of 17 patients diagnosed during the past 10 years at Asan Medical Center, Seoul, Korea. We performed an immunohistochemical staining in 17 cases of LK and 7 cases of LP using 5 antibodies for CD3, CD4, CD8, CD20, and cutaneous lymphocyte-associated antigen (CLA). Standard streptavidin-biotin peroxidase method using the monoclonal antibodies with 3-amino-9-ethyl-carbazole was used. RESULTS: The male/female ratio was 1:1.1. The mean age at diagnosis was 54.9 years. The face was the most commonly affected site, followed by the arm and forearm, dorsum of hand, chest, trunk, abdomen, and leg. The lesions were predominantly solitary (76.5%); 1 patient had 4 lesions; 3 patients (17.6%) had numerous lesions. The lesions ranged in size from 0.4 to 2.0 cm. Histopathologically, all the cases showed characteristic lichenoid infiltrates of lymphocytes, occasional parakeratosis, and apoptotic bodies in the epidermis without nuclear atypia of keratinocytes. LK could be reclassified into 3 patterns by means of histopathologic findings: LP-like (11/17), seborrheic keratosis-like (3/17), and lupus erythematosus-like (3/17). Immunohistochemical studies revealed that infiltrated epidermal and dermal lymphocytes in LK consisted mainly of CD8(+) T cells and partly CD20(+) B cells. In LP, epidermal lymphocytes were mainly CD8(+) T cells and dermal lymphocytes were CD4(+) or CD8(+) T cells. Interestingly, CLA was strongly expressed in LP but not expressed in LK. CONCLUSION: We reclassified LK as follows: LP-like LK, seborrheic keratosis-like LK, and lupus erythematosus-like LK. Immunohistochemical stains for CLA as well as CD4 and CD8 may be valuable tools in the differential diagnosis between LK and LP.

Adult↗