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Biomedical subjects

E H Choi

Publications and source records attributed to E H Choi.

At least 19 recordsLinked to original sources
PubMed2004

25 Hydroxyvitamin D 1 alpha-hydroxylase is required for optimal epidermal differentiation and permeability barrier homeostasis.

Keratinocytes express high levels of 25OHD 1alpha-hydroxylase (1OHase). The product of this enzyme, 1,25-dihydroxyvitamin D (1,25(OH)(2)D), promotes the differentiation of keratinocytes in vitro suggesting an important role for this enzyme in epidermal differentiation. To test whether 1OHase activity is essential for keratinocyte differentiation in vivo we examined the differentiation process in mice null for the expression of the 1alphaOHase gene (1alphaOHase(-/-)). Heterozygotes for the null allele were bred, and the progeny genotyped by PCR. The epidermis of the 1alphaOHase(-/-) animals and their wild-type littermates (1alphaOHase(+/+)) were examined by histology at the light and electron microscopic level, by immunocytochemistry for markers of differentiation, and by function examining the permeability barrier using transepidermal water loss (TEWL). No gross epidermal phenotype was observed; however, immunocytochemical assessment of the epidermis revealed a reduction in involucrin, filaggrin, and loricrin-markers of differentiation in the keratinocyte and critical for the formation of the cornified envelope. These observations were confirmed at the electron microscopic level, which showed a reduction in the F (containing filaggrin) and L (containing loricrin) granules and a reduced calcium gradient. The functional significance of these observations was tested using TEWL to evaluate the permeability barrier function of the epidermis. Although TEWL was normal in the basal state, following disruption of the barrier using tape stripping, the 1alphaOHase(-/-) animals displayed a markedly delayed recovery of normal barrier function. This delay was associated with a reduction in lamellar body secretion and a failure to reform the epidermal calcium gradient. Thus, the 25OHD 1OHase is essential for normal epidermal differentiation, most likely by producing the vitamin D metabolite, 1,25(OH)(2)D, responsible for inducing the proteins regulating calcium levels in the epidermis that are critical for the generation and maintenance of the barrier.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed2003

The characterization of molecular organization of multilamellar emulsions containing pseudoceramide and type III synthetic ceramide.

To investigate the molecular organization and phase behavior of physiologic lipid mixtures that contain either newly synthesized pseudoceramide or type III synthetic ceramide, various analytical techniques were used. The phase transition temperatures detected in differential scanning calorimetry analysis were 51.19 and 50.52 for the pseudoceramide-containing physiologic lipid mixture and synthetic type III ceramide-containing lipid mixture, respectively. From the small angle XRD patterns, the multilamellar emulsion-pseudoceramide showed 11.5 nm and 7.61 nm lamellar phases, while the multilamellar emulsion-synthetic ceramide showed only a 7.61 nm lamellar phase. The nonceramide containing lipid mixture did not show any distinct repeat pattern. Lateral packing distances of multilamellar emulsion-pseudoceramide and multilamellar emulsion-synthetic ceramide were measured as 0.4119 and 0.4110 nm at 30, respectively, which indicated the presence of hexagonal lattice. On the contrary, non-multilamellar emulsion did not show any definite repeat pattern. Transmission electron microscopy observation showed nearly comparable lamellar structures in all of the tested emulsions compared to the structure of human stratum corneum intercellular lipid. Decrease of water contents resulted in phase transition into liquid phase for all the tested emulsions, whereas phase transition into orthorhombic phase was observed only in multilamellar emulsion-pseudoceramide. From these results, we concluded that the molecular organization of multilamellar emulsion-pseudoceramide was characterized as the lateral hexagonal phase and both the long and short periodicity lamellar phases, which showed structural similarity with the native human stratum corneum intercellular lipid.

Anisotropy↗
PubMed2002

The skin barrier state of aged hairless mice in a dry environment.

BACKGROUND: Many elderly people have chronic xerosis, and frequently experience an exacerbation during winter. OBJECTIVES: To investigate the barrier state of aged murine skin with or without barrier disruption in a dry environment. METHODS: Aged and young hairless mice were kept separately in dry and normal conditions for 9 days. Acetone treatment was used to perturb the skin barrier. Skin barrier function was measured as transepidermal water loss (TEWL), and morphological changes in the epidermis were studied by electron microscopy. RESULTS: The baseline TEWL was not higher in the dry environment. The number of stratum corneum (SC) layers and the epidermal thickness of aged mice increased in the dry environment. The recovery rate of the aged skin barrier was neither accelerated nor delayed in the dry environment. In the normal environment, aged mice recovered more slowly than young mice. After barrier perturbation in the aged mice, changes in SC layers and in epidermal thickness were similar in the two environments. The secretion and number of lamellar bodies did not differ between the two environments. CONCLUSIONS: We confirmed that a dry environment induces epidermal proliferation and scaling in both aged and young mice. However, no remarkable difference was found in the skin barrier recovery of aged hairless mice in a dry environment.

Acetone↗
PubMed2001

Lower respiratory tract infections due to adenovirus in hospitalized Korean children: epidemiology, clinical features, and prognosis.

On occasion, outbreaks of infection with adenovirus types 3, 7, and 21 cause severe lower respiratory tract infections (LRTIs) in children. From 1990 to 1998, all cases of LRTI due to adenovirus at the Seoul National University Children's Hospital, Seoul, Korea, were reviewed. Adenoviruses were recovered from nasal aspirate specimens of 87 (5.9%) of 1472 children with LRTI. The principal adenovirus serotypes were type 2 (13 [15%] of 87 strains), type 3 (13 [15%]), and type 7 (36 [41%]). Of the 87 infections, 62 (71%) occurred in children <2 years of age, and 81 (94%) occurred in children <5 years of age. Infections due to types 3 and 7 occurred during epidemics, whereas infections due to type 2 occurred sporadically. For patients who were infected with types 3 and 7, extrapulmonary abnormalities were more common and homogeneous consolidation and pleural effusion were frequently identified on radiographs. The mortality rate was 12% overall and 19% among patients who were infected with type 7. Residual sequelae were identified in 6 (50%) of 12 patients who were infected with type 3 and in 9 (25%) of 36 who were infected with type 7. The data confirm that adenovirus types 3 and 7 can cause epidemics of severe LRTI in young children. Epidemics of LRTIs caused by adenovirus types 3 and 7 in Korea have not been described in reports published elsewhere.

Adenovirus Infections, Human↗
PubMed2001

Functional and structural changes of the epidermal barrier induced by various types of insults in hairless mice.

Acute barrier disruption, regardless of the method of induction, depletes the stratum corneum intercellular lipids and this stimulates a series of lipid/ DNA synthesis activities which lead to barrier recovery. After barrier disruption by tape stripping, occlusion with a water vapor-impermeable membrane inhibits barrier repair. In this study, we investigated the changes in the murine epidermis after barrier perturbation by tape stripping and three different types of surfactants (Emalex NP-12, ENP-12; sodium dodecyl sulfate, SDS; benzalkonium chloride, BKC). To examine the effect of an artificial barrier, we covered the animals with a water vapor-impermeable membrane for 3 days following barrier disruption and then exposed them to the air for 2 days. The histological findings after occlusion or air exposure were similar. However, after air exposure for 2 days, the thickness of the epidermis including the stratum corneum and the stratum granulosum layers decreased to about half that of the epidermis after occlusion. Ultrastructural examination revealed obvious distortion of the lamellar bilayers within the stratum corneum interstices immediately after barrier disruption. After 3 days of occlusion, extensive disorganization was evident in the intercellular domain of the stratum corneum, whereas 2 days after removal of the occlusion, the normal basic unit structure of the lamellar bilayers had partially reappeared. Our findings provide evidence that the kinetic pattern of barrier repair and the morphological changes are similar after occlusion following barrier disruption regardless of the mechanism of disruption.

Animals↗
PubMed2001

Using genetic variation to study human disease.

The generation of a draft sequence of the human genome has spawned a unique opportunity to investigate the role of genetic variation in human diseases. The difference between any two human genomes has been estimated to be less than 0.1% overall, but still, this means that there are at least several million nucleotide differences per individual. The study of single nucleotide polymorphisms (SNPs), the most common type of variant, is likely to contribute substantially to deciphering genetic determinants of common and rare diseases. The effort to identify SNPs has been accelerated by three developments: the availability of sequence data from the genome project, improved informatic tools for searching the former and high-throughput genotype platforms. With these new tools in hand, dissecting the genetics of disease will rapidly move forward, although a number of formidable challenges will have to be met to see its promise realized in clinical medicine.

Genetic Predisposition to Disease↗
PubMed2001

Genetic polymorphisms in molecules of innate immunity and susceptibility to infection with Wuchereria bancrofti in South India.

A pilot study was conducted to determine if host genetic factors influence susceptibility and outcomes in human filariasis. Using the candidate gene approach, a well-characterized population in South India was studied using common polymorphisms in six genes (CHIT1, MPO, NRAMP, CYBA, NCF2, and MBL2). A total of 216 individuals from South India were genotyped; 67 normal (N), 63 asymptomatic microfilaria positive (MF+), 50 with chronic lymphatic dysfunction/elephantiasis (CP), and 36 tropical pulmonary eosinophilia (TPE). An association was observed between the HH variant CHIT1 genotype, which correlates with decreased activity and levels of chitotriosidase and susceptibility to filarial infection (MF+ and CP; P = 0.013). The heterozygosity of CHIT1 gene was over-represented in the normal individuals (P = 0.034). The XX genotype of the promoter region in MBL2 was associated with susceptibility to filariasis (P = 0.0093). Since analysis for MBL-sufficient vs insufficient haplotypes was not informative, it is possible the MBL2 promoter association results from linkage disequilibrium with neighboring loci. We have identified two polymorphisms, CHIT1 and MBL2 that are associated with susceptibility to human filarial infection, findings that merit further follow-up in a larger study.

Animals↗
PubMed2001

Effect of head rotation on lateral cephalometric radiographs.

The purpose of this study was to identify the potential projection errors of lateral cephalometric radiographs due to head rotation in the vertical Z-axis. For this investigation, 17 human dry skull samples with permanent dentition were collected from the Department of Anatomy in the College of Medicine, Chosun University. They had no gross asymmetry and were well preserved. Each dry skull was rotated from 0 degrees to +/- 15 degrees at 1 degrees intervals. A vertical axis, the Z-axis, was used as a rotational axis to have 527 lateral cephalometric radiographs exposed. The findings were that: (1) angular measurements have fewer projection errors than linear measurements; (2) the greater the number of landmarks on the midsagittal plane that are included in angular measurements, the fewer the projection errors occurring; (3) horizontal linear measurements decrease gradually in length as the rotational angle toward the film increases, whereas a small increase and then decrease of the length occurs as the rotational angle toward the focal spot increases; (4) horizontal linear measurements have more projection errors than vertical linear measurements according to head rotation; and (5) projection errors of vertical linear measurements increase as the distance from the rotational axis increases. In summary, angular measurements of lateral cephalometric radiographs are more useful than linear measurements in minimizing the projection errors associated with head rotation on a vertical axis.

Cephalometry↗
PubMed2001

The effects of topical alpha-hydroxyacids on the normal skin barrier of hairless mice.

BACKGROUND: alpha-hydroxyacids (AHA), such as glycolic acid and lactic acid, have recently been used in cosmetic and dermatological formulations. However, the mechanisms of action of these substances have not been well documented. OBJECTIVES: This study was done to investigate the effects of AHA on the skin barrier of hairless mice and to clarify the contribution of AHA to the formation and secretion of the lamellar bodies (LB), which are known to be the critical structure for barrier function in the epidermis. METHODS: 5% Lactic acid and 5% glycolic acid were applied to normal skin of the mice daily for 14 days. RESULTS: Changes in transepidermal water loss (TEWL), capacitance and electron microscopic findings of the epidermis of hairless mice were compared with those in which only the vehicle was applied. CONCLUSIONS: There were no significant differences in TEWL, capacitance or epidermal thickness between the epidermis of the mice to which AHA or vehicle only had been applied. On electron micrographs, the normal epidermis to which AHA had been applied showed an increase in the number and secretion of LB and a decrease in the number of stratum corneum (SC) layers in comparison with the epidermis to which the vehicle only had been applied. The lipid layers of the SC intercellular spaces and calcium gradient in both the epidermis with application of AHA and that with vehicle only were normal. These results suggest that AHA, in low concentration (5%), may improve the skin barrier in hairless mice by inducing enhanced desquamation, and by increasing the number and secretion of LB without increasing TEWL.

Animals↗
PubMed2001

Basis of occlusive therapy in psoriasis: correcting defects in permeability barrier and calcium gradient.

BACKGROUND: Although occlusive dressings have great potential in the management of psoriasis vulgaris, the therapeutic mechanism is not completely understood. Occlusion artificially restores and corrects the defective barrier in psoriasis plaques. Additionally, occlusion is know to normalize the epidermal calcium gradients in hyperproliferative murine skin models. METHODS: To investigate the basis of the therapeutic effect of occlusion on psoriatic plaques, we investigated the ultrastructural morphology of intercorneocyte lipid layers, lamellar bodies, and calcium gradient in chronic plaque-type psoriasis after occlusion with a water vapor-impermeable membrane. The specimens were processed for electron microscopy using: (i) ruthenium tetroxide postfixation; and (ii) ion-capture cytochemistry for calcium localization. RESULTS: Occlusion for 7 days resulted in a nearly mature pattern of intercellular multilamellar structures, re-establishment of the near-normal epidermal calcium gradient, and disappearance of calcium precipitates from the stratum corneum interstices. CONCLUSIONS: The normalization of the permeability barrier and epidermal calcium gradient may play important roles in the therapeutic effects of occlusive dressings in chronic plaque-type psoriasis.

Calcium↗
PubMed2001

The effects of famciclovir and epidural block in the treatment of herpes zoster.

In our previous study, we concluded that an epidural blockade combined with intravenous acyclovir is very effective in treating the acute pain in herpes zoster and postherpetic neuralgia. We evaluated the efficacy of oral famciclovir and epidural blockade on the pain of herpes zoster, compared to acyclovir administered intravenously and epidural blockade. For this purpose, we examined a new group treated with famciclovir and epidural blockade to compare with the group treated with acyclovir and epidural blockade in our previously study. The changes in the intensity of pain, the number of days required for relief of pain, and the total duration of pain were checked. We compared the days required for relief of pain (DRP) and the total duration of pain (TDP) of this group with those of the previous studied group treated with acyclovir and epidural blockade. DRP was significantly less, but TDP was similar. DRP and TDP were significantly lower, if the patients were treated within 7 days of symptom onset. The patients had a shorter DRP regardless of pain type than the previously studied group treated with acycolvir and epidural blockade. For the severe and moderate pain grades, there was a shorter DRP from 100 to 10. TDP was not significantly different for the groups regardless of pain type or grade. We believe that famciclovir and epidural blockade are very effective in treating the pain of herpes zoster, with a view to shortening the period of acute pain, providing similar effects on the prevention of postherpetic neuralgia, and being convenient to administer, compared to intravenous acyclovir and epidural blockade in our previous study.

2-Aminopurine↗
PubMed2001

Evolution of TEM-related extended-spectrum beta-lactamases in Korea.

TEM-52, differing from TEM-1 by having the substitutions Glu-104-->Lys, Met-182-->Thr, and Gly-238-->Ser, has previously been described as the most prevalent extended-spectrum beta-lactamase (ESBL) in Korea. In a further survey, we discovered the ESBLs TEM-15, which is like TEM-52 but lacks the substitution at residue 182, and TEM-88, which is like TEM-52 with an additional Gly-196-->Asp substitution. TEM-88 retained the activity of TEM-52 against moxalactam. Otherwise, the kinetic properties of the three ESBLs failed to show an advantage to this evolution.

Anti-Bacterial Agents↗
PubMed2001

Identification of CTX-M-14 extended-spectrum beta-lactamase in clinical isolates of Shigella sonnei, Escherichia coli, and Klebsiella pneumoniae in Korea.

CTX-M-14 beta-lactamase was identified in a stool isolate of Shigella sonnei and in blood isolates of Escherichia coli (one isolate) and Klebsiella pneumoniae (two isolates) from different parts of Korea. The amino acid sequence differed by one amino acid from CTX-M-9 (Ala-231--> Val) and was identical to that of beta-lactamases recently found in China and Japan.

Amino Acid Sequence↗
PubMed2001

Modulation of cytochrome P4501-mediated bioactivation of benzo[a]pyrene by volatile allyl sulfides in human hepatoma cells.

Allyl sulfides such as diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS), typical flavor components of Allium vegetables, have been shown to inhibit benzo[a]pyrene (B[a]P)-induced carcinogenesis in animal models. As a possible mechanism of this inhibition, the effect of these volatile substances on cytochrome P450 (CYP)1 (CYP1A1, 1A2 and 1B1)-mediated bioactivation of B[a]P was investigated using a human hepatoma cell model (HepG2). DADS and DATS inhibited the B[a]P-induced ethoxyresorufin O-deethylase (EROD) activity, a marker enzyme for CYP1, by 30-90% and 70-95% at 100-1,000 microM concentration, respectively. The cell viability, an indicator of the capacity to inhibit B[a]P bioactivation, was increased by treatments of 100-1,000 microM DADS and 10-100 microM DATS. Immunoblot results indicated that the B[a]P inducible CYP1A2 protein was suppressed by 100-1,000 microM of DADS and 10-100 microM of DATS, but CYP1A1 and 1B1 were not detectable in any microsomes. Analysis of B[a]P metabolites revealed that the level of 7,8-diol formed was significantly reduced in the DADS and DATS treated microsomes as compared to the control. The level of 9,10-diol and 4,5-diol formed was also lowered by the allyl sulfide treatments. These results suggest that the protective mechanism of allyl sulfides on B[a]P-induced carcinogenesis is possibly related with the modulation of CYP1-mediated bioactivation of B[a]P.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2001

Complications of eyelash and eyebrow tattooing: reports of 2 cases of pigment fanning.

Eyelash and eyebrow tattooing are commonly performed procedures that have a very low rate of reported complications. We describe one case of infraorbital pigmentation after eyelash tattooing and another of periorbital pigmentation after eyebrow tattooing. Although most complications related to eyelash and eyebrow tattooing, including pigment fanning, have been reported by ophthalmologists, pigment fanning is also of concern to dermatologists.

Adult↗
PubMed2000

Genetic diversity and molecular epidemiology of the G protein of subgroups A and B of respiratory syncytial viruses isolated over 9 consecutive epidemics in Korea.

To study genetic variation and molecular epidemiology of the G protein of respiratory syncytial virus (RSV), 253 strains from a children's hospital in Korea over 9 consecutive epidemics were analyzed. Restriction analysis of the entire G protein gene demonstrated 24 genotypes among 188 subgroup A and 6 among 65 subgroup B isolates. Two to 4 dominant genotypes of subgroup A cocirculated, and different genotypes predominated in each epidemic. Predominant genotypes were replaced with new genotypes during consecutive epidemics. One of 2 dominant genotypes among subgroup B predominated alternately or concurrently. Phylogenetic analysis revealed that there were multiple lineages, with clustering related to their location and time of isolation among strains from Korea and worldwide. Geographic and temporal distinction have been shown more clearly for subgroup B than subgroup A. These results suggest that the G protein of RSV is continuously evolving, with a distinct pattern presumably due to immune selection in a localized region over time.

Amino Acid Sequence↗