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Biomedical subjects

J G Choi

Publications and source records attributed to J G Choi.

8 recordsLinked to original sources
PubMed2001

Transdermal delivery of ketoprofen using microemulsions.

A transdermal preparation containing ketoprofen was developed using O/W microemulsion system. Of the oils tested, oleic acid was chosen as the oil phase of the microemulsion, as it showed a good solubilizing capacity and excellent skin permeation rate of the drug. Pseudoternary phase diagrams were constructed to obtain the concentration range of oil, surfactant and cosurfactant for microemulsion formation, and the effect of these additives on skin permeation of ketoprofen was evaluated with excised rat skins. The optimum formulation of the microemulsion consisted of 3% ketoprofen, 6% oleic acid, 30% Labrasol/Cremophor RH 40 (1:1) and water. Terpenes were added to the microemulsion at the level of 5% and their effect on the skin permeation of ketoprofen from the microemulsion was evaluated. Of the four terpenes used, only limonene resulted in a powerful enhancing activity (3-fold increase over control).

Administration, Cutaneous↗
PubMed2001

Electrophoretron: a new method for enhancing resolution in electrokinetic separations.

Two capillaries, each of which have different surface preparations on their inside walls, are joined together to form a closed loop, and electrodes are placed inside the two capillaries. When the loop is filled with liquid and a potential difference is applied between the two electrodes, a circulating flow of liquid is established inside the loop because the resistance to flow is unequal in going from one electrode to another in a clockwise versus a counterclockwise direction. Consequently, a sample injected into this device, which we call an electrophoretron, repeatedly circulates between the two electrodes and the capillary separation column becomes effectively one of unlimited length. On each cycle the separation between analytes with different mobilities increases, thus enhancing resolution of analytes having nearly the same mobilities. The operation of a prototype electrophoretron is demonstrated.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2001

Domain and genomic sequence analysis of bdellin-KL, a leech-derived trypsin-plasmin inhibitor.

Bdellin-KL is a trypsin-plasmin inhibitor from Hirudo nipponia, whose N-terminal sequence was identified as a non-classical Kazal-type. A cDNA clone encoding the inhibitor was isolated by reverse transcription-PCR and 5' rapid amplification of cDNA ends. The cDNA showed an open reading frame of 155 amino acids comprising one signal peptide and two separated domains. The C-terminal domain consists of distinct internal repeats, including HHEE and HHDD. The bdellin-KL sequence, from the constructed genomic library of Korean leech, was determined for the 2109 bases comprising the open reading frame and flanking regions (3' and 5'). The promoter region contains potential regulatory sequence motifs, including TATA, CAAT, and GC boxes. To characterize the properties of each domain, an N-terminal fragment was prepared by limited proteolysis of the intact protein. The inhibitory activity of the region was as potent as that of the intact protein. This suggests that the compact domain plays an important part in the inhibitory action of bdellin-KL. The C-terminal domain was revealed to have binding affinity to ions such as Ca(2+), Zn(2+), Fe(3+), and Fe(2+) without an influence on the inhibitory activity. This study demonstrates that bdellin-KL may be a novel bifunctional protein with two distinct domains.

Animals↗
PubMed2001

Apoptosis, bcl2 expression, and cell cycle analyses in nickel(II)-treated normal rat kidney cells.

Nickel compounds are carcinogenic to human and are potent inducers of kidney and lung tumors in experimental animals. In this study, the effects of nickel(II) acetate on apoptosis, cell cycle and bcl2 expression in normal rat kidney (NRK- 52E) cells were investigated. Nickel(II) induced apoptosis in NRK-52E cells as demonstrated by DNA laddering. Apparent DNA laddering was observed in cells treated with 480 microM for 48 hr. In the flow cytometric analysis using propidium iodide fluorescence, an increase of cell proportion in G2/M phase was shown in cells exposed to at least 320 microM of nickel(II) acetate, from 7.7% for 0 microM of nickel(II) to 16.5% for 480 microM of nickel(II) acetate. Induction of apoptotic cell death by nickel(II) was accompanied by reduction of bcl2 protein expression, while the level of p53 protein was not changed. Taken together, our data indicate that nickel(II)-induced apoptosis in NRK-52E cells is accompanied by G2/M cell cycle arrest, regardless of p53 function, and that bcl2-mediated signaling pathway may be involved in positive regulation of nickel(II)-induced apoptotic cell death in NRK-52E cells.

Acetates↗
PubMed1998

Multiple lentigines syndrome: a comparison of normal skin and lentiginous skin by electron microscopy and immunohistochemical staining.

A 26-year-old Korean man exhibited generalized lentigines, a slight prominence of the chin, short stature, and a familial history consistent with the autosomal dominant mode of inheritance. The multiple lentigines appeared at the age of 1 and spread over his entire body including the scalp, palms, and soles by the age of 4. There were several large dark pigmented spots on the trunk, but no other skin abnormalities were found. We performed histologic studies of the normal skin and the lentigo by both electron and light microscopy with immunohistochemical stains. Routine hematoxylin-eosin staining of the pigmented skin revealed heavily pigmented basal and spinous layers and prominent rete ridges. Fontana-Masson stain showed enormous black pigmentations on the basal and spinous layers of the pigmented macule. S-100 protein stain of the pigmented lesion demonstrated an increased number of melanocytes per unit skin area. Ultrastructural studies showed the presence of extensive aggregated melanosomes within the keratinocytes in the epidermis of lentigo, but not the presence of giant melanosomes in either normal skin or lentigines.

Adult↗