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Biomedical subjects

E H Choi

Publications and source records attributed to E H Choi.

68 records · Page 4Linked to original sources
PubMed1995

Studies on the transposition rates of mobile genetic elements in a natural population of Drosophila melanogaster.

In an isolated population of Drosophila melanogaster on Ishigaki Island the chromosomal distribution of several retrotransposons, including copia, 412, 297, 17.6, I, and jockey elements, was examined by in situ hybridization. In this population the cosmopolitan inversion, In(2L)t, is known to exist in high frequency. One major haplotype concerning the occupied sites of the transposable elements was identified in the In(2L)t-carrying chromosomes. This haplotype is suggested to be the ancestral one. The age of the inversion in this local population was estimated to be 1,400 generations. The transposition rates of these elements were estimated based on the age of the inversion and the number of the elements lost and gained. The excision rates were in the range from 9.13 x 10(-5) to 2.25 x 10(-4) per site per generation. They were similar each other in the copia-like elements as well as in the LINE-like elements. The rate was higher in the copia-like elements than in the LINE-like elements. Insertions occurred in the range from 6.79 x 10(-4) to 9.05 x 10(-4) per element per generation. It is herein shown that both insertions and excisions occurred at a significantly higher rate in this population than in the laboratory.

Animals↗
PubMed1995

Viral etiology and epidemiology of acute lower respiratory tract infections in Korean children.

Viral etiologic agents of acute lower respiratory tract infections were studied from November, 1990, through April, 1994, in Korean children. From 712 children who visited or were admitted to Seoul National University Children's Hospital because of acute lower respiratory tract infections, 804 nasal aspirates were collected; viral agents were detected by virus isolation and virus antigen was detected by indirect immunofluorescent staining. One or more viral agents were identified in 369 (45.9%) cases; of which 3.3% were mixed infections. The pathogens identified were respiratory syncytial virus (27.2%), parainfluenza virus type 3 (7.8%), influenza A virus (3.9%), adenovirus (3.9%), parainfluenza virus type 1 (1.7%), influenza B virus (1.4%), parainfluenza virus type 2 (0.5%), measles virus (0.1%) and others (0.9%). The clinical patterns of viral lower respiratory tract included pneumonia (56.6%), bronchiolitis (35.2%), croup (6.5%) and tracheo-bronchitis (1.6%). Infections with respiratory syncytial virus, parainfluenza virus types 1 and 3 and influenza A and B virus occurred in epidemics, whereas adenovirus was isolated sporadically throughout the study period. The data expand our understanding of the epidemiology of acute viral lower respiratory tract infections in Korean children and may be helpful to the clinicians and researchers interested in the control of viral respiratory tract infections.

Acute Disease↗
PubMed1995

Idiopathic solitary neuroma of skin with unusual histologic changes.

We report herein a case of idiopathic solitary neuroma with vascular proliferation and neurofibroma-like features. Clinically, the skin lesion was a 0.7 cm nodule without tenderness on the forearm. Histologically, there was vascular proliferation in the upper dermis, some neural structures among the proliferative vasculature in the mid dermis and large bundles of neural structures extending in various directions in the mid and deep dermis (resembling neurofibroma). Special stains, such as Masson's trichrome and Luxol fast blue, and immunohistochemical studies, including S-100 protein, neuron-specific enolase (NSE), vimentin, desmin, factor-VIII related antigen and epithelial membrane antigen (EMA), were added for this very rare case.

Adult↗
PubMed1995

Acute renal failure associated with Yersinia pseudotuberculosis infection.

Since 1987, we have experienced 11 children with acute renal failure (ARF) associated with Yersinia pseudotuberculosis (YP) infection. The illness began with the sudden onset of high fever, skin rash and gastrointestinal symptoms. Later in the course, periungual desquamation developed, mimicking Kawasaki disease. Elevated erythrocyte sedimentation rate, C-reactive protein and thrombocytosis were noticeable, and mild degrees of proteinuria, glycosuria and sterile pyuria were common. ARF, which typically developed about 1-3 weeks after the onset of fever, underwent a benign course with complete recovery. The renal biopsies mainly revealed findings of acute tubulointerstitial nephritis. YP should be considered as one of the causes of acute tubulointerstitial nephritis causing ARF, especially in children.

Acute Kidney Injury↗
PubMed1994

Immunohistochemical studies from vitiligo--comparison between active and inactive lesions.

Vitiligo is an acquired, progressive depigmenting disorder of unknown etiology. In this study, to clarify pathogenesis of vitiligo, the marginal skin of actively spreading and stable vitiligo was examined using ICAM-1, HLA-DR, CD4 and CD8 monoclonal antibodies. In immunohistochemical study, ICAM-1 was expressed in four of five epidermis in active lesions, but not in stable lesion. Dermal ICAM-1 was also expressed in all active and stable lesions. HLA-DR was also expressed in all active epidermis in active lesions, but two of five epidermis in stable lesion. Dermal HLA-DR was also expressed in all active and stable lesion. CD4 lymphocytes were expressed more strongly in active lesion, but CD8 lymphocytes were not different in both lesions. There was no significant difference of degree of positivity with CD4 and CD8 in normal control specimens. In conclusion, we think that ICAM-1 and HLA-DR expression, cytokines released from keratinocytes, melanocytes or lymphocytes and infiltration of activated T-lymphocytes play an important role in disease activity.

CD4 Antigens↗
PubMed1992

Epidermal changes in active vitiligo.

Light and electron-microscopic studies were performed on the vitiligo and adjacent, normal appearing skin from 97 patients with actively spreading vitiligo and 19 patients with stable vitiligo. The vitiliginous skin revealed complete loss of pigment and melanocytes. In addition to degenerative changes in melanocytes, vacuolar changes of basal cells, epidermal infiltration of lymphocytes, dermal infiltration of lymphocytes, and melanophages in the upper dermis were also seen in the normal appearing skin adjacent to vitiliginous skin. These epidermal and dermal changes are more prominent in the skin of actively spreading vitiligo than in stable vitiligo. These findings suggest that the adjacent, normal appearing skin of actively spreading vitiligo shows some characteristic histopathologic findings, especially in the epidermis, indicating that cellular immunity could be involved in the pathogenesis of vitiligo.

Acute Disease↗
PubMed1992

Acne fulminans and 13-cis-retinoic acid.

We report a case of acne fulminans occurring during treatment with 13-cis-retinoic acid for cystic acne. Continuing the treatment with 13-cis-retinoic acid without systemic steroid eventually cleared the systemic manifestations and skin lesions. We review the literature and discuss its pathogenesis.

Acne Vulgaris↗
PubMed1992

Hair follicle nevus.

Four cases of hair follicle nevi are described. Hair follicle nevus is an extremely rare hamartoma occurring on the face, which has had no clear histopathologic definition until now. A short review of the clinicopathologic features of this disease is presented.

Adult↗
PubMed1991

Confluent and reticulated papillomatosis: a clinical, histopathological, and electron microscopic study.

The clinical, histopathological, and electron microscopic features of ten patients with confluent and reticulated papillomatosis (CRP) of Gougerot and Carteaud were studied. Histopathologically, hyperkeratosis, decreased granular layer, irregular papillomatosis, and hypermelanosis of the basal layer were present. In an electron microscopic study, we found transitional cells between the stratum granulosum and stratum corneum that were increased in CRP. This finding supported the suggestion that this is a defect of keratinization.

Adolescent↗
PubMed1985

Construction of killer wine yeast strain.

A double-stranded RNA plasmid which confers the superkiller phenotype was transferred into a wine yeast (Montrachet strain 522) and its leucine-requiring derivative (strain 694) by cytoduction, using the protoplast fusion technique. The killer wine yeast constructed completely suppressed the growth of killer-sensitive strains of Saccharomyces cerevisiae in yeast extract-peptone-glucose medium at pH 4.5, whereas the killer effect was somewhat decreased at pH 3.5. The wine yeast harboring the killer factor also inhibited the growth of killer-sensitive cells satisfactorily when it was grown in grape juice.

Journal Article↗
PubMedDate not supplied

The efficacy of treatment with triamcinolone acetonide in calcinosis cutis following extravasation of calcium gluconate: a preliminary study.

Neonatal hypocalcemia is not an uncommon condition, especially in the premature neonate. It is effectively treated by intravenous administration of calcium gluconate. Complications of extravasation during intravenous infusion include localized calcification and occasionally necrosis. When this occurs, however, there is no specific mode of treatment except supportive management and skin graft. This experiment was designed to evaluate the efficacy and safety of treatment with triamcinolone acetonide in calcinosis cutis following extravasation of calcium gluconate. Initially, 2 cc of 10% calcium gluconate was injected subcutaneously into two rabbits at seven sites on the shaved skin of the back. Another two rabbits were injected at the same sites with 0.5 cc of triamcinolone acetonide (10 mg/dl) after injection of 2 cc of 10% calcium gluconate. As a control, 2 cc of normal saline was injected into another rabbit in the same manner. These five rabbits were observed over the next 7 weeks and underwent pathologic examination at various intervals (on days 1, 3, 8, 15, 30, 37, 45). In the 10% calcium gluconate injected rabbits, nodules and large ulcerated lesions developed after 15 days. Multiple, linear, ulcerative and indurated masses were noted on day 37. The lesions healed progressively with a decrease in ulceration, and after 2 months, the masses disappeared gradually. Histologically, on day 15 calcium deposits were seen in the walls of the arteries, veins, dermis, and muscle fibers and epidermal necrosis was seen at the injection sites. From day 37 discharge of calcium deposits began to take place by means of transepidermal elimination. After 2 months, the calcium and mucin deposition was observed focally in the dermis. In the rabbits injected with 10% calcium gluconate and triamcinolone acetonide, mild erythema and induration were seen after day 15 at the injection sites; this gradually disappeared. After 30 days the injection sites were normal in appearance. Histologically, at day 15 calcium deposition was seen in the upper dermis, but after 1 month the injection sites were histologically normal. We suggest that intralesional injection of triamcinolone acetonide for the treatment of calcinosis cutis following extravasation of calcium gluconate is effective, probably due to its antiinflammatory effect and its role in facilitating the resorption of calcium in the tissue.

Administration, Topical↗
PubMedDate not supplied

The pretreatment effect of chemical skin penetration enhancers in transdermal drug delivery using iontophoresis.

The transdermal drug delivery (TDD) system has largely been divided into physical, biochemical and chemical methods. Recently, combinations of these methods were introduced for more effective delivery with less side effects. We performed this study to identify the effectiveness and mechanism of TDD using the physical method, 'iontophoresis', plus the chemical method, 'pretreatment with chemical enhancer'. The action sites of chemical enhancers in the stratum corneum (SC) were observed by electron microscope. We also studied whether this combined method synergistically impaired the skin barrier. To confirm the synergistic effect on skin penetration by this combined method, we measured the blood glucose level after insulin iontophoresis following a chemical enhancer pretreatment in rabbits. The results were that (1) dilatation of the intercellular lipid layers of the SC and lacunae was prominent in pretreatment with chemical enhancers inducing high transepidermal water loss (TEWL); (2) the skin barrier impairment, with repeated treatments showing an increased TEWL and also epidermal proliferation, was increased with the chemical enhancers that showed a high TEWL immediately after treatment; (3) the combination of chemical enhancer pretreatment and iontophoresis showed no synergistic impairment of the skin barrier, and (4) the chemical enhancer pretreatment with greater impairment of the skin barrier could increase the delivery of insulin by iontophoresis. The results showed that a combination of chemical enhancer pretreatment and iontophoresis could deliver drugs more effectively than iontophoresis alone. Our proposed theory is that iontophoretic drug delivery may be easier through the dilated intercellular spaces of the SC which have a lower electrical impedance following the chemical enhancer pretreatment. Because the effect and the side effects in the combination are decided by the chemical enhancer rather than iontophoresis, the development of proper chemical enhancers is important in future plans.

Administration, Cutaneous↗